fantastic power plant audit

Indo German Energy Programme of 168 Report Date 28.09.2008 Output 1.1

D:\Guptha\Steag\GTZ\Deliverables Finals\NEW IGEN Output 1.1 Report 2008 09 29.doc

Power Plant Performance Reporting and Improvement

under the Provision of the Indian Energy Conservation Act

Output 1.1

Best practice performance monitoring, analysis of performance procedures, software and analytical tools, measuring instrumentation, guidelines or best practice

manuals and newest trends



Table of Contents

1. General.................................................................................................. 14

1.1 Survey 'best practise' with basic Definition of Efficiency Indicators ................... 15

1.2 Analysis including Tools for Efficiency Indicators.............................................. 15

1.3 Instrumentation on Efficiency Indicators ........................................................... 16

1.4 Guidelines for basic Definition of Efficiency Indicators...................................... 16

1.5 Energy Audit ..................................................................................................... 16

1.6 Performance/ Benchmarking Analysis ............................................................... 16

1.7 Strategic Outlook (newest Trends & Research) .................................................. 17

2. Power Scenario in Europe....................................................................... 18

2.1 Development of European & Global Electricity Demand..................................... 18

2.2 Availability, coverage and import dependency of Energy Sources ..................... 19

2.3 Primary Energy Saving through efficient use of Electricity ................................. 20

2.4 Power Plant portfolio in EU................................................................................ 21

2.5 Power Plant projects in Europe.......................................................................... 21

2.6 Pros & Cons of relevant Energy Generation Options.......................................... 23

2.7 Requirement of efficient coal and gas Power Plants .......................................... 25

3. Directives Applicable to Large Combustion Plants.................................. 27

3.1 Legal basis in the EU ......................................................................................... 27

3.2 Underlying information ..................................................................................... 27

3.3 Document organisation..................................................................................... 28

3.4 The European Energy Industry........................................................................... 28

3.5 Applied technologies ........................................................................................ 28

3.6 Ecological issues ............................................................................................... 29



3.7 Conditions ........................................................................................................ 29

3.8 Unloading, storage and transport of fuels and additives ................................... 30

3.9 Pre-treatment of fuel ........................................................................................ 32

3.10 Fine dust emissions .......................................................................................... 33

3.11 Heavy metals..................................................................................................... 34

3.12 SO2 emissions................................................................................................... 35

3.13 NOx emissions................................................................................................... 36

4. Best Available Techniques to increase Efficiency and reduce Emissions.. 39

5. State of the Art -Reference Power Plant (Source VGB)............................. 40

5.1 Brief Overview ................................................................................................... 40

5.2 Details of the Study........................................................................................... 41

5.3 Innovations ....................................................................................................... 41

5.4 Layout Planning................................................................................................. 42

5.5 Thermodynamic Design .................................................................................... 42

5.6 Steam Turbine Plant (Turbine, Generator) ......................................................... 44

5.7 High-Pressure Turbine section.......................................................................... 44

5.8 Intermediate-Pressure Turbine section ............................................................. 45

5.9 Low-Pressure Turbine section........................................................................... 46

5.10 Generator Plant ................................................................................................. 47

5.11 Boilers ............................................................................................................... 48

5.12 Water and Steam Cycle...................................................................................... 50

5.13 Cooling Water Systems...................................................................................... 51

5.14 Technological Options ...................................................................................... 52

5.15 Summary........................................................................................................... 55

6. Role of 700°C Technology for the Carbon-free Power Supply ................. 61



6.1 Introduction and Background............................................................................ 61

6.2 Status 700°C Technology .................................................................................. 62

6.3 Current and Coming Activities of the 700°C Technology................................... 66

6.4 Perspectives of the 700°C Technology............................................................... 69

6.5 Regulatory and Political Framework .................................................................. 70

7. Road Map to High Efficiency Power Plant................................................ 72

8. Technology Platform for Zero Emission Power Plants by 2020................ 73

9. Definition of Efficiency Parameters - Basics ........................................... 74

9.1 Efficiency........................................................................................................... 74

9.2 Losses of Efficiency in Combustion Plants......................................................... 75

9.3 Generic Technical Measures to improve Large Combustion Plant's Efficiency.... 76 9.3.1 Combustion ...................................................................................................... 76 9.3.2 Unburned Carbon in Ash................................................................................... 77 9.3.3 Air Excess ......................................................................................................... 77 9.3.4 Steam................................................................................................................ 77 9.3.5 Flue-Gas Temperature ...................................................................................... 78 9.3.6 Vacuum in the Condenser ................................................................................. 78 9.3.7 Variable Pressure and fixed Pressure Operation................................................ 78 9.3.8 Condensate and Feed-Water Preheating ........................................................... 79

10. Energy Balance ...................................................................................... 80

10.1 Efficiency of German Power Plants..................................................................... 81

10.2 Efficiency Degradation ...................................................................................... 82

10.3 Energy Balance of a Coal-Fired Power Plant Unit ............................................... 82

10.4 Operating efficiency in European Power Plants.................................................. 84

10.5 Operating Efficiency of typical Indian Power Plants compared to German Power



Plants ................................................................................................................ 87

10.6 Comparison of published efficiencies ............................................................... 88

11. Key parameters and basis for measurements......................................... 91

11.1 Key operating parameters ................................................................................. 91

11.2 Fuel Parameter .................................................................................................. 92

11.3 Air & Flue Gas Parameters ................................................................................. 93

11.4 Data required .................................................................................................... 93

12. Official Statistics for Efficiency Indicator and Plant Reliability ................. 95

12.1 Reports on Analysis and Tools for Efficiency Indicators .................................... 95

12.2 Excerpts from Eurostat-Document.................................................................... 96

13. Performance Indicators & Monitoring..................................................... 97

13.1 Introduction ...................................................................................................... 97

14. Software and Analytical Tools for Efficiency and Plant Reliability –Online and Offline ................................................................................................. 102

14.1 Introduction .................................................................................................... 102

14.2 Software Analytical Tools / Modules ............................................................... 103

14.3 Data Collection for the Performance Monitoring ............................................. 103

14.4 Analysis for Performance Monitoring .............................................................. 104

14.5 K I S S Y........................................................................................................... 105

14.6 Systems for Optimized Operation ................................................................... 107

14.7 Lifetime Monitoring System............................................................................. 114

14.8 Data Management System............................................................................... 116

14.9 Thermodynamic Cycle Calculation Program – Offline Tool .............................. 117

15. Benchmarking of Power Plant Operation & Management ...................... 121



15.1 General ........................................................................................................... 121

15.2 Basics of Benchmarking .................................................................................. 121

15.3 Benchmarking of Thermal Power Plants .......................................................... 122

15.4 Benchmarking Methodology............................................................................ 123

15.5 Project Organization ....................................................................................... 129

16. Energy Audit – Situation in the EU respectively Germany ...................... 131

16.1 Status.............................................................................................................. 131

17. Overview on Regulations, Guidelines Efficiency/Plant Performance ...... 148

18. Example: Computerized Plant and Energy Management Systems at the Evonik Steag Voerde Power Plant ......................................................... 153

19. Latest (state of the art) technologies and status................................... 155

19.1 Technology Perspectives – Availability vs. State of the Art .............................. 155

19.2 Atmospheric Fluidized Bed Firing System........................................................ 155

19.3 Pressurized Fluidized Bed Firing System ......................................................... 156

19.4 Gasification of Coal (IGCC) .............................................................................. 159

19.5 Turbulent Pulverised-Coal Burner ................................................................... 160

19.6 Supercritical Technology ................................................................................. 163

19.7 Six Sigma Concept .......................................................................................... 164

20. Operating Efficiency of EU Power Plants and Efforts initiated for Improvement ....................................................................................... 165

20.1 Rationale ......................................................................................................... 165

21. Best Practices Applicable to Indian Scenario......................................... 166

21.1 Online monitoring System............................................................................... 166

21.2 Statistical Process Control Process Detection .................................................. 166



21.3 Simulator Training on Power Plant Operation.................................................. 166

21.4 Maintenance Management Systems................................................................. 167

21.5 Benchmarking Practices .................................................................................. 167

22. Miscellaneous ...................................................................................... 168



Abbreviations

an Analysis moisture BAT Best Available Technique BDEW Verband der Deutschen Energie-, Gas-, und Wasserwirtschaft CCS Carbon capture and storage CFBF Circulating fluidised bed firing system dai Dry adsorbent injection (flue gas desulphurisation) DIN Deutsche Industrienorm (German DIN Standard) ESS Electrostatic separator EU European Union FBF Fluidised bed firing FF Fibrous filter FGD Flue gas desulphurisation GCV Gross caloric value hd Half-dry (flue gas desulphurisation) HHV Higher heat value HP High pressure kWh Kilo Watt hour LCP Directive on Large Combustion Plants lftraf Air-dry and ash-free LHV Lower heat value LP Low pressure MP Medium pressure NCV Net caloric value PFBF Pressure fluidised bed firing system Pm Primary measures reducing the NOx raw Raw SCR Selective catalytic NOx reduction SF Dust combustion SFBF Stationary fluidised bed firing system SNCR Selective non-catalytic NOx reduction TWh Tera watt-hours VDI Vereinigung der deutschen Industrie (Association of German Engineers,



www.vdi.de) VGB European Association for Generation of Heat and Power, www.vgb.org) waf Water and ash-free wf Water-free wmf Water and mineral-compound free



Terms and Definitions

Dimension e Proportional auxiliary consumption - f Specific fuel consumption kg/kWh

oH Upper heating value kJ/kg uH Lower heating value kJ/kg tk Time availability h Wk Energy avalability - fm& Mass flow of the fuel kg/s, kg/h sm& Mass flow of the steam kg/s, kg/h

tn Time utilisation - wn Energy utilisation - eP Net generator output kW genP Generator capacity kW iP Gross generator output kW NP Nominal capacity MWel netP High-voltage side net generator output kW ownP Electrical auxiliary consumption kW eq Specific net heat consumption kJ/kWh, kJ/kWs fQ Average fuel heat kg/s, kg/h, kg/month FWQ Feed water heat capacity supplied to the

boiler kg/s

nRHQ Heat quantity without reheating supplied to the boiler

kg/s

RHQ Reheated heat quantity supplied to the machine

kg/s

SGQ Useful thermal quantity input into the process

kg/s

SSQ Superheated steam heat quantity input into the machine

kg/s

es Number of successful start-ups - ns Number of unsuccessful start-ups - Bt Operating time h



Dimension Nt Reference period h vt Available time h

BW Energy generated MWh NW Nominal energy MWh vW Unavailable energy MWH

z Start-up reliability - heatQ& Useful thermal heat kJ/kg

η Efficiency - beη Boiler efficiency - clη Losses of thermodynamic cycle - elη Electrical efficiency - fuη Degree of fuel use - thη Thermal efficiency of the turbine - trη Efficiency of machine transformer - totη Total efficiency -



List of Annexures

Annexure I LCP Directive 2001 /80/ EC

Annexure II 13. BImSchV –Ordinance of implementation of Federal immission control act (English version)

Annexure III Best Available Techniques

Annexure IV State of the Art Reference Power Plant incl. its appendices I to VIII

Annexure V The Evonik Steag Road to the high efficiency power plant

Annexure VIa Roadmap for low carbon power supply ETP ZEP SRA and SDD study

Annexure VIb Roadmap for low carbon power supply ETP ZEP SRA and Strategic Research Agenda

Annexure VII Definition of Efficiency parameters

Annexure VIII The complexity of thermal power plant efficiencies reporting in India and Germany” (By Dr. Kaupp, GTZ) Best available techniques to increase efficiency and reduce emissions

Annexure IX Basis for measurements and parameters to be monitored

Annexure X Analysis and tools for efficiency indicator

Annexure XI Excerpts from Eurostat Document

Annexure XII KISSY instructions & Excerpts from performance report

Annexure XIII IGCC technology

Annexure XIV Supercritical and ultra super critical technology

Annexure XV CFBC technology

Annexure XVI Six sigma process

Annexure XVII PFBC technology Annexure XVIII Advanced Technologies of Preventive Maintenance for Thermal Power

Plants-write up by Hitachi

Annexure XIX Oxyfuel technology for fossil fuel-fired power plants – Dresden University of Technology, Germany

Annexure XX Results of oxy-fuel combustion for power plants- Dresden University of Technology, Germany

Annexure XXI Actual efficiency of thermal power plants in Europe, efficiency improvement over a period of time



Annexure XXII On line Monitoring System

Annexure XXIII Statistical Process Control – Fault Detection

Annexure XXIV Simulator Training

Annexure XXV Maintenance Management Systems

Annexure XXVI Monitoring and Controlling of power plants

Annexure XXVII Maintenance Practices

Annexure XXVIII Design Criteria of Thermal Power Plants

Annexure XXIX Stores Inventory and Procurement System



1. General

A detailed survey on best practice power plant performance monitoring and was undertaken primarily in Germany/Europe by VGB and EESG. After the survey detailed report is prepared which covers the following outputs:

• survey 'best practise power plant performance monitoring in Germany/ Europe' with basic definition of efficiency indicators including samples of reporting

• basic definition of efficiency indicators • software and analytical tools including tools for efficiency indicators used

online and offline • instrumentation on efficiency indicators • guidelines/best practice manuals including VGB • energy auditing practise • analysis of performance procedure • strategic outlook (newest trends & research)

With a view the cover the above activities, the report is structured in to two parts: PART I: The initial part of the report gives an overall report about the electric power market in Europe including a compilation of the power plant projects in Europe. Further a description of the state of the art for electric power technologies as well as the perspective for future developments and the legal prescription for the emission limits according to the EU regulations is given. The intention of this general introduction is to give a better understanding to the specific situation in Europe and Germany in particular.

• power scenario in Europe • directives in the EU applicable to large combustion plants • best available techniques for large combustion plants • best practices to increase efficiency and reduce the emissions • state of the art – Reference power plant



• new trends – Role of 700 °C technology • future perspectives – Carbon Capture & Storage

PART II The later part of the report describes the best practise power plant performance monitoring in Germany/Europe.

• efficiency parameters definitions • energy balance • basics for the measurements and parameters • overview of regulations and guidelines for efficiency and plant performance • performance indicators and monitoring of power plants • software and analytical tools for efficiency indicators and plant optimisation

– Online & Offline • benchmarking in thermal power plants as part of performance indicator • energy Audit • other relevant papers and reports

1.1 Survey 'best practise' with basic Definition of Efficiency Indicators

This document summarizes the technical and physical basis for plant performance indicators - oriented on the indicators needed and the necessary measurement devices. The report covers the definitions of the plant technical indicators as well as the correlated physical measurement units. 1.2 Analysis including Tools for Efficiency Indicators

Based on the selected and described indicators samples for standard reports used in the EU are given. These official reports are published by national authorities as well as industrial organisations like the VGB. The key tool is the control system on the plant process consisting of a measurement device, software transferring the physical unit into a plant indicator and an analysis tool in



order to be able to react 1.3 Instrumentation on Efficiency Indicators

The plant measurement system is part of control & instrumentation system; the plant process control system is also part of the above-mentioned system. 1.4 Guidelines for basic Definition of Efficiency Indicators

A distinction is drawn between legal and industrial regulations in the EU. Concerning the industrial regulations the VDI-guidelines are irrelevant for the report on hand; their main focus is on the design area. The main focus of the VGB-guidelines is on the operation area which has to be considered in this report. 1.5 Energy Audit

In the EU are a wide-spread set of directives (to be transposed into national law) targeting the energy sector. There are no regulations for the efficiency of electric power generation. In the past in the EU we had discussions to implement regulations, but at the end the conclusion was that market-driven mechanism are more effective. This position was supported by the fact that the electric power generation in the EU is the most efficient worldwide. 1.6 Performance/ Benchmarking Analysis

Benchmarking of power plant involves development of essential technical and organizational elements for the long-term commercial sustainability of the power plant operation.



1.7 Strategic Outlook (newest Trends & Research)

The state of the art in the EU is a consistent system covering the whole chain of measurement, algorithm and analysis tools, available by all the suppliers. Prerequisite for the successful use of these instruments is to raise the awareness of the staff in applying these tools. Research work is mainly concentrating on a closer intercommunication of the technical tools with the business tools like SAP.



PART I 2. Power Scenario in Europe

2.1 Development of European & Global Electricity Demand

(Source: VGB Power Tech –Facts and Figures –Electricity generation 2007, http://www.vgb.org/en/data_powergeneration.html) The global population is increasing by 78 million people per year. Consequently, the population has doubled during the last five decades. At present, approximately one quarter of the global population of 6.5 billion do not have access to electricity. As a result, electricity consumption is growing faster than any other form of energy. It is expected that present global electricity consumption of 16,595 TWh is expected to double to roughly 30,673 TWh by the year 2030. One-fifth of the electricity generated globally – roughly 3,300 TWh – is required in the European Union (EU). A 30 % rise in demand is expected by 2030. Experts estimate that fossil fuels will continue to cover most of the extra demand. Fossil fuels will still account for roughly 70 % of electricity generated worldwide in 2030. About 60 % of electricity generated in the EU will come from fossil fuels by that time. Renewable energy sources will play increased role in the global primary energy consumption structure. Likewise, nuclear power will maintain an important position in global electricity generation and will even grow in some countries. Expected growth in electricity generation in EU by the year 2030 is 30 % (ie expected requirement is 4,300x109 kWh). While worldwide growth in electricity generation by the year 2030 is 85 % (i.e, expected requirement is 31,673 x 109 kWh)



2.2 Availability, coverage and import dependency of Energy Sources

Existing primary energy reserves and resources, after including renewable energy sources, are adequate in terms of fossil fuels and uranium around the world. Hard coal and Lignite as well as uranium are the most widespread. However, energy sources have an uneven geographical distribution, which means that some countries and regions, including the European Union, are becoming increasingly dependent on imports. The EU’s fossil fuel reserves amount to approximately by 75,000 million tonnes of coal equivalent, accounting for only 5% of the known reserves worldwide, and consist mainly of lignite and hard coal. The natural gas and oil reserves amount to approximately 5,000 million tonnes of coal equivalent. Europe’s dependency on imported coal will grow from approximately by 30 % today to more than 60% by the year 2030. An import dependency of 81 % is expected for natural gas and of as much as 88 % for oil. Overall, the share of imported energy will increase from approximately from 50% today to roughly 70% by 2030. The causes of this are the nuclear phase-out chosen by some countries, along with the decreasing of cost-effectively exploitable European energy reserves. Only lignite will still be extractable from open cast mines at competitive costs in some countries in the long term. Figure 2-1 gives the development of dependence of imports of EU from 1990 to 2030.

Figure 2-1: Dependence of Imports of EU



18

81

48 45

30

77

50 47

37

81

61

5350

86

75

6266

8881

67

0

10

20

30

40

50

60

70

80

90

100

Solid fuels Oil Natural gas Total

Perc

enta

ge

1990 2000 2010 2020 2030

2.3 Primary Energy Saving through efficient use of Electricity

The link between growth in gross domestic product and primary energy consumption has become weaker in many developed nations in the last few years, due to increased application of electricity facilitating many rationalisation processes. On the one hand, this development reflects the trend towards a service based society; on the other hand, the progress in energy production and its use, for example more efficient power plants, tailored energy application through electronic control or even heat pumps, is playing an important role. The expected use of electric vehicles in the future may reinforce this trend even more. Saving primary energy will therefore require more electricity. There is a risk that forced electricity savings will impair the balance of primary energy and emission cuts unnecessarily.



2.4 Power Plant portfolio in EU

Total installed capacity of power plants in EU is 752,060 MW, which includes 27 countries. Of which Germany accounts for 18 % of the total EU. Figure 2-2 shows a break up of power plants' installed capacity in the EU.

Figure 2-2: Power plant portfolio in EU

Power Plant Portfolio in EU (2005)- Total 752060 MW

1322

65

1155

00

8676

2

8180

0

7595

3

3321

2

2154

4

1901

3

1741

2

1699

7

1659

5

1635

2

1364

5

1332

0

1262

3

9555

3743

5

3207

7

0

20000

40000

60000

80000

100000

120000

140000

Ger

man

y

Fran

ce

Italy UK

Spai

n

Swed

en

Pola

nd

Ned

erla

nds

Aus

tria CR

Rom

ania

Finl

and

Belg

ium

Gre

ece

Port

ugal

Den

mar

k

Bulg

aria

Oth

ersM

W

2.5 Power Plant projects in Europe

The replacement demand for old power plants and the increase in electricity consumption in Europe have led many utilities and other investors to make plans for new projects. In addition, taking into account also the CO2 emission trading and a worldwide increase in energy demand, coal, natural gas and nuclear power will continue to be the most important primary energy sources for electricity generation. Currently, around 67,000 MW of new build projects based on natural gas have been announced. New build projects based on lignite, hard coal and peat have a combined plant capacity of around 37,300 MW today.



Two new nuclear power plants with a total capacity of around 3,200 MW are being constructed in the EU in Finland (Olkiluoto) and France (Flamanville), and nuclear power plants with a total capacity of a further 4,082 MW are being planned in Bulgaria, Romania and the Slovak Republic. In addition, output is being increased at existing plants. New power plant capacity of roughly 52,780 MW is currently being planned based on renewable energy sources such as wind, hydropower and biomass. In total, projects with a joint capacity of roughly 167,395 MW have been announced. Whether all of the announced new build projects will actually be realised will depend greatly on future primary energy price trends and political conditions (country-specific bonus/malus regulations) due to CO2 reduction strategies. Figure 2-3 gives break up of proposed (or planned) power plants with regard to the energy source. Figure 2-3: Planned power projects in EU

Planned Power Projects in EU (total 167395 MW)

67005

2500

33263

4075 7770469 3233 187

48805

880

1000020000300004000050000600007000080000

Gas Oil

Har

dco

al

Lign

ite

&Pe

at

Nuc

lear

Biom

ass

Hyd

ropo

wer

Resi

dues

& w

aste

Win

d

Oth

erRE

S

MW

It is shown that renewable energies (including wind power) have taken a major share of 32 % (i.e, 52,782 MW).



2.6 Pros & Cons of relevant Energy Generation Options

At present 46% of the total electricity is generated in Eurpoe is CO2 free. The following Figure 2-4 gives the break up of the power generation. Figure 2-4: Break up of power generation

Nuclear30%

Coal31%

Gas20%

Hydro10%

Wind2%

Biomass, waste, oil, etc

7%

The following Table 2-1 gives pros and cons of relevant electricity generation projects

Table 2-1: Pros and cons of power generation options

Energy Source Pros Cons Nuclear • Climate-protecting

electricity generation with

no CO2 emissions

• Cost-effective and reliable

supply with no critical

import dependency

• High safety standard at

western nuclear power

plants

• Social acceptance problem

in some European

countries

• Long licensing process

under nuclear law

• Extensive effort and cost

required for safety

• Disposal and final storage

of nuclear fuel not yet

resolved politically

Coal • Hard coal can be procured

cost-effectively by many

providers on the world

• Growing demand for hard

coal (predominantly from

China and India) and



Energy Source Pros Cons market

• Brown coal in Europe is a

readily available domestic

raw material

• Power plant technology

has great potential for

efficiency improvement

limited transport capacities

entail price risks

• CO2 emissions higher than

for natural gas

• Flue gas require cleaning

with corresponding cost

and effort for plants

Gas • Most environmentally

friendly fossil fuel

relatively low CO2

emissions

• Electricity generation in

highly efficient power

plants

• Short erection times and

low investment costs for

new plants

• Volatile natural gas prices

are leading to large

fluctuations in electricity

generation costs

• Dependency on imports

from a possible supply risk

• Increasing concentration of

export sources in

politically unstable regions

Wind • Climate-protecting

electricity generation with

no CO2 emissions

• High plant efficiency

• Cost-effective operation

• Network services are

available extremely quickly

• Flood protection support

• Serious obstacles imposed

by new environmental

protection targets

• Expansion of existing

potential is problematic for

environmental policy

reasons

• High investment costs for

new plants due to

extensive compensatory

measures not relating to

electricity generation

Hydro • Climate-protecting

• Electricity generation with

no CO2 emissions

• Serious obstacles imposed

by new environmental

protection targets



Energy Source Pros Cons • High plant efficiency

• Cost-effective operation

• Network services are

available extremely quickly

• Flood protection support

• Expansion of existing

potential is problematic for

environmental policy

reasons

• High investment costs for

new plants due to

extensive compensatory

measures not relating to

electricity generation

2.7 Requirement of efficient coal and gas Power Plants

CO2 emissions can be reduced gradually through technological development. The volume of CO2 produced from hard coal electricity generation can be reduced by around 35 % worldwide if low-efficiency power plants (the average global efficiency factor currently stands at 30 %) were replaced by power plants with a 46 % efficiency factor (current state of the art power plants). Therefore, the gradual reduction of CO2 emissions by technological development is the first option. It would result in profitable on three counts:

• resource protection, as less fuel is required for generating the same amount of electricity

• substantial reduction in CO2 emissions • increased electricity generation from the same fuel amount

In the long term, electricity generation from fossil fuels could take place virtually CO2-free through capture and underground storage of CO2. The potential for CO2-reduction of coal-fired power plants is shown in the following Figure 2-5 (Source VGB). Figure 2-5: Reduction potential in CO2



EU

1. 38%

2. 881

3. 480

State of the

art

1. 45%

2. 743

3. 320

Steam power plant 700oC technology

1. >50 %

2. 669

3. 288

2010 2020

CCS technology

Year

Average

Worldwide

1. 30%

2. 1.116

3. 480

1. Efficiency

2. CO2 Emissions gram of CO2 per kWh 3. Fuel consumption g/kWh



3. Directives Applicable to Large Combustion Plants

3.1 Legal basis in the EU

The European LCP-Directive 2001/80/EC (see annexure I) applies to combustion plants, the rated thermal input of which is equal to or greater than 50 MW, irrespective of the type of fuel used (solid, liquid or gaseous). In addition to this it shall apply only to combustion plants designed for production of energy with the exception of those, which make direct use of the products of combustion in manufacturing processes. The LCP-Directive defines emission limit values for the discharge of substances from the combustion plant into the air. These emission limit values define the permissible quantity of a substance contained in the waste gases from the combustion plant which may be discharged into the air during a given period; it shall be calculated in terms of mass per volume of the waste gases expressed in mg/Nm3, assuming an oxygen content by volume in the waste gas of 3% in the case of liquid and gaseous fuels, of 6% in the case of solid fuels and 15% for gas turbines. Member States of the EU should bring into force the laws, regulations and administrative provisions necessary to comply with the LCP-Directive. Germany had brought into force the 13. BImSchV, it implements the regulations of the LCP-Directive (English version of 13. BimSchV see annexure II). 3.2 Underlying information

Numerous documents, reports and information from member states, the industry, plant operators and authorities, as well as equipment suppliers and institutions active in environmental protection, have been called on. Further information was gathered during site visits in various European member states and in personal discussions on issues regarding the choice of technology and experiences during the application of reduction techniques.



3.3 Document organisation

In Europe, the Power and/or Heat Generation sector is a heterogeneous industrial sector. The energy generation is based on numerous fuels, generally to be divided according to their state of aggregation into solid, liquid or gaseous fuels. Therefore this document has been vertically organised so that the individual fuels are listed successively, where joint aspects and techniques are described together, however, in the three introductory chapters. 3.4 The European Energy Industry

Within the European Union every available type of energy source is used for the generation of power and heat. In individual EU member states the selection of the fuel used for energy generation is largely based on the national fuel resources, e.g. on the local or national availability of hard coal, brown coal, biomass, peat, crude oil and natural gas. Since 1990, the share in electric power generated from fossil fuel energy sources has increased by approximately 16 %, while the demand increased by approx. 14 %. The share of the electric power generated from renewable energy sources (including hydroelectric power and biomass) increased by almost 20 %, which is higher than average. Combustion plants are operated either as large supply plants or as industrial combustion plants providing driving power (e.g. in the form of electric power, mechanical energy), steam or heat for industrial production processes. 3.5 Applied technologies

A variety of combustion techniques are applied to the energy generation overall. For the combustion of solid fuels, dust combustion, fluidised bed firing systems and grate firing are all considered conceivable (published by the EU in the BAT data sheet: "Reference Document on Best Available Techniques for Large Combustion Plants", on the conditions described in this document. The possible status of liquid and gaseous fuels corresponds to appropriate boilers, engines and gas turbines on the conditions described in this document.



The system to be used is selected on the basis of the economic, technical, ecological and local requirements such as availability of the fuels, operational requirements, market conditions and requirements of the mains. Electric power is mainly generated by generating steam in a boiler fired with the selected fuel. This steam is supplied to a turbine that drives a generator, generating electric power. The degree of efficiency of the steam cycle is limited by the requirement to liquefy the steam after it leaves the turbine. Some liquid and gaseous fuels can be fired directly in order to drive turbines with combustion gas or they can be used in internal combustion engines driving the generator. Every technology offers certain advantages to the plant operator, especially regarding its operational suitability with regard to variable energy requirements. 3.6 Ecological issues

Most combustion plants use fuels and other raw materials mined from the Earth’s natural resources, in order to convert them into useable energy. Fossil fuels are the most widely available energy source currently used. However, their combustion leads to an important and sometimes significant burden for the environment as a whole. The combustion process causes the development of emissions into the air, water and soil, with air pollution considered one of the most severe ecological burdens. The most significant emissions developing during the combustion of fossil fuels are SO2, NOx, CO, fine dust (PM10) and greenhouse gases such as N2O and CO2. Further substances such as heavy metals, halogenated compounds and dioxins are discharged in smaller quantities. 3.7 Conditions

The possible emission values are based on daily average values, standard conditions and an O2 content of 6 % / 3 % / 15 % (solid fuels / liquid and gaseous fuels / gas turbines), and refer to a typical burden situation. Brief peak values during peak loads, start-up and shutdown processes and operational malfunctions of the exhaust gas cleaning systems,



which might be higher, must be reckoned with. 3.8 Unloading, storage and transport of fuels and additives

In Table 3-1 some options are summarised for avoiding emissions during unloading, storage and transport of fuels and additives such as lime, limestone, ammonia etc.

Table 3-1: Some options to avoid emissions during unloading, storage and transport of fuels and additives

Best possible technology Fine dust • Using loading and unloading equipment

with as small a drop to the storage heap as possible to reduce the development of diffuse emissions (solid fuels).

• Using water spray systems in countries with no risk of frost to reduce the development of diffuse emissions during the storage of solid fuels (solid fuels).

• Arranging transfer conveyors in safe surface areas outdoors so that damage by vehicles and other equipment can be avoided (solid fuels).

• Using enclosed conveyors with well designed, robust ventilation and filter equipment at conveyor transfer locations to avoid dust emission (solid fuels).

• Optimising the transport systems to minimise dust development and transport on location (solid fuels).

• Applying the principles of excellent



Best possible technology design and construction practice and appropriate maintenance (all fuels).

• Storing lime or limestone in silos with well designed, robust ventilation and filter equipment (all fuels).

Water contamination • Storage on sealed, drained surfaces, collection of drained water and water treatment in settling tanks (solid fuels).

• Using storage systems for liquid fuels with impermeable protective walls able to hold 75 % of the maximum capacity of all tanks or at least the maximum contents of the largest tank.

• The content of the tank should be indicated and an appropriate alarm system used; in order to avoid overfilling the storage tank, automatic control systems can be used (solid fuels).

• Installing pipelines in safe surface areas outdoors so that leaks can be determined quickly and damage by vehicles and other equipment avoided. For inaccessible pipelines, double-walled pipes can be used with an automatic gap control (liquid and gaseous fuels).

• Collecting the runoff water (rain water) from fuel stores and treating this collected flow (settling tanks or waste water treatment plant) prior to discharging waste water (solid fuels).



Best possible technology Fire protection • Monitoring the storage areas for solid

fuels with automatic systems, in order to detect spontaneous combustion and determine danger zones (solid fuels).

Diffuse emissions • Using leak detection systems for burner gas and alarm systems (liquid and gaseous fuels).

Efficient use of natural resources • Using expansion turbines for the recovery of the energy contents of the pressurised burner gases (natural gas supplied via pressure pipes) (liquid and gaseous fuels).

• Preheating the burner gas by using the waste heat of the boiler or gas turbine (liquid and gaseous fuels).

Health and safety risk due to ammonia • For the transport and storage of pure liquid ammonia: pressure vessels for pure liquid ammonia > 100 m3 should be designed with a double wall and located below ground; vessels with a capacity not exceeding 100 m3 should be manufactured applying the annealing treatment (all fuels).

• Considering the safety aspect, using aqueous ammonia is less dangerous than storing and handling pure liquid ammonia (all fuels).

3.9 Pre-treatment of fuel

For solid fuels, the pre-treatment of the fuel mainly consists in blending and mixing in order to ensure stable combustion conditions and to reduce emission peaks.



3.10 Fine dust emissions

The fine dust discharged during the combustion of solid or liquid fuels is almost exclusively composed of the mineral components. During the combustion of liquid fuels, poor combustion conditions lead to the development of soot. The combustion of natural gas does not constitute a significant dust emission source. In this case, the dust emission values are usually far less than 5 mg/Nm3, without the application of additional technical measures.

Table 3-2: Options regarding the reduction of fine dust emissions in fossil fired combustion plants, excepting gas combustion plants (excerpt from LCP-Directive)

Dust emission values (mg/Nm3)

Hard coal Liquid boiler fuels

Thermal combustion

output

(MWth) New plants Existing plants

New plants Existing plants

Option achieving

these values

50 – 100

5 - 20

5 - 30

5 - 20

5 – 30

ESS or FF

100 – 300

5 - 20

5 - 25

5 - 20

5 – 25

> 300

5 - 10

5 - 20

5 - 10

5 – 20

ESS or FF in combination

with FGD (wet, hd or dai) for SF,

ESS or FF for FBF



Abbreviations: Dai dry adsorbent injection ESS electrostatic separator FBF fluidised bed firing FF fibrous filter FGD flue gas desulphurisation Hd half-dry SF dust combustion

For the dedusting of exhaust gases in new and existing combustion plants, the applicable state of technology is the use of an electrostatic separator (ESS) or a fibrous filter (FF), where emission values below 5 mg/Nm3 are usually achieved by using a fibrous filter. Cyclone separators and mechanical dedusters alone cannot be considered sufficient; however, they can be used as a prepurification stage within the exhaust gas process. The possible state of technology regarding dedusting and the corresponding emission values are compiled in the table below. For combustion plants exceeding 100 MWth, and especially exceeding 300 MWth, the dust values are lower because flue gas desulphurisation processes, which are already state of the art for desulphurisation in Germany and the EU, also achieve a reduction of the fine dust. 3.11 Heavy metals

The emission of heavy metals results from their occurrence as a natural component in fossil fuels. Most of the heavy metals to be considered (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, Zn) are usually released in the form of compounds (e.g. oxides, chlorides) together with dust. Therefore it is usually possible to reduce the heavy metal emissions by installing high-efficiency dedusting plants such as electrostatic separators or fibrous filters. Only Hg and Se occur at least partially in the steam phase. At the typical operating temperatures of separation plants, mercury indicates a high steam pressure and its separation with fine dust reduction facilities fluctuates significantly. With electrostatic separators or fibrous filters operated in combination with exhaust gas desulphurisation processes such as the limestone wash process, the spray absorption process or the dry adsorbent injection, the average Hg separation level is 75 % (50 % for electrostatic separators and 50 % for exhaust gas desulphurisation plants), and with an additionally



available selective catalytic reduction (SCR) in high-dust arrangement (arrangement between boiler and dust separator), it is possible to achieve 90 %. 3.12 SO2 emissions

Emissions of sulphur oxides mainly result from the sulphur occurring in the fuel. In general, natural gas is considered sulphur-free. With certain technical gases this is not the case, and in these cases desulphurisation of the gaseous fuel may be necessary. For combustion plants fired with solid and liquid fuels, the use of low-sulphur fuels and/or desulphurisation is usually an option. Table below (Table 3-3) gives various options regarding the reduction of SO2 emissions in hard and brown coal combustion plants (excerpt from LCP-Directive).

Table 3-3: Options regarding the reduction of SO2 emissions in hard and brown coal combustion plants (excerpt from LCP-Directive)

SO2 emission values (mg/Nm3)

Hard and brown coal

Thermal combustion

output

(MWth) New plants Existing plants

Option achieving these values

50 – 100 200 - 400* 150 - 400*

(FBF)

200 - 400* 150 - 400*

(FBF)

100 – 300 100 - 200

100 - 250*

> 300 20 - 150* 100 - 200

(CFBF/PFBF)

20 - 200* 100 - 200* (CFBF/PFBF)

Low-sulphur fuel or/and FGD (dai) or

FGD (hd) or FGD (wet) (depending on the

plant size). Cleaners using seawater.

Combined process reducing NOx and

SO2. limestone injection (FBF).



Abbreviations: CFBF circulating fluidised bed firing system dai dry adsorbent injection FBF fluidised bed firing system FGD flue gas desulphurisation hd half-dry PFBF pressure fluidised bed firing system

In most cases for plants exceeding 100 MWth, however, the use of low-sulphur fuel can only be taken into account as a supplementary measure in combination with other measures reducing the SO2 emissions. In addition to using low-sulphur fuels, desulphurisation by means of a wet cleaner (reduction rate 92 – 98 %) and the spray absorption process (reduction rate 85 – 92 %) are mainly considered applicable techniques, with a market share of more than 90 % already. Dry exhaust gas desulphurisation processes such as dry adsorbent injection are mainly used for plants with a thermal output of less than 300 MWth. The advantage of the wet cleaner is that it also reduces emissions of HCl, HF, dust and heavy metals. For plants with an output of less than 100 MWth, the wet cleaning process is not considered ideal due to high costs. 3.13 NOx emissions

The most significant nitrogen oxides discharged during combustion are nitrogen monoxide (NO) and nitrogen dioxide (NO2), with common designation NOx. For hard coal dust combustion plants, it is possible to reduce the NOx emissions with primary and secondary measures such as selective catalytic reaction (SCR), where the reduction rate of the SCR system is between 80 % and 95 %. The disadvantage of the application of SCR or SNCR is possible emissions of unconverted ammonia ("ammonia leak"). For small plants without major load fluctuations fired with solid fuels and with a stable fuel quality, the SNCR process is also considered a possible application to reduce NOx emissions.



This means the use of sophisticated low-NOx burners in combination with other primary measures such as exhaust air return, staged combustion (air grading), fuel grading, etc. The application of primary measures tends to encourage incomplete combustion, causing a higher concentration of unburned carbon within the fly ash and a certain amount of carbon monoxide emissions. For boilers with a fluidised bed firing system firing solid fuels, a reduction of the NOx

emission is possible by distributing the air or returning the exhaust gas. The NOx emissions from stationary and circulating fluidised bed firing systems differ slightly. Table 3-4 shown below enables conclusions regarding the minimisation of the NOx emissions and the corresponding emission values for hard coal.

Table 3-4: Options regarding the reduction of NOx emissions in hard coal combustion plants using different combustion techniques (excerpt from LCP-Directive)

NOx emission values (mg/Nm3) Thermal combustion

output

(MWth)

Combustion technique



grate firing 200 - 300 200 - 300 Pm and/or SNCR

SF 90 - 300 90 - 300 Combination of Pm and SNCR or SCR

50 – 100

SFBF & PFBF 200 - 300 200 - 300 Combination of Pm

SF 90 - 200 90 - 200 Combination of Pm together with SCR

or combined process

100 – 300

SFBF, CFBF & PFBF

100 - 200 100 - 200 Combination of Pm together with

SNCR



NOx emission values (mg/Nm3) Thermal combustion

output

(MWth)

Combustion technique



SF 90 - 150 90 - 200 Combination of Pm together with SCR

or combined process

> 300

SFBF, CFBF & PFBF

50 - 150 50 - 200 Combination of Pm

Abbreviations: CFBF circulating fluidised bed firing system PFBF pressure fluidised bed firing system Pm Primary measures reducing the NOx SCR selective catalytic NOx reduction SF dust combustion SFBF stationary fluidised bed firing system SNCR selective non-catalytic NOx reduction



4. Best Available Techniques to increase Efficiency and reduce Emissions

For clean and new boilers, it can be stated that the efficiency levels around 86 % - 94 % (LHV), are currently recorded for solid fuel, The main losses are associated with flue-gas waste heat via the stack, unburned carbon, waste heat in ash and radiation losses. The effect of fuel is important, assuming boilers with identical performance (same ambient and flue-gas temperature, same excess air, etc.) different boiler efficiencies are obtained depending on the nature of fuel as the following examples illustrate (LHV basis):

Fuel Efficiency [%] International coal 94 Lignite 92 Low grade lignite 86

The best practices/best available techniques to increase efficiency and reduce the emissions are given in annexure III.



5. State of the Art -Reference Power Plant (Source VGB)

5.1 Brief Overview

The study on the "Reference Power Plant" has been produced with the aim of developing a 600 MW capacity hard-coal fired power plant operating at efficiency of 45.9%, concept that is sustainable in the future and will meet these challenges. The main aims of the concept study are to examine the feasibility of a modern power plant with sharply reduced emissions, taking account of the economic conditions that prevail in the deregulated energy market, and also to demonstrate the opportunities for North Rhine-Westphalia (Germany) as an industrial location. Operating on a hard coal Efficiency of over 48% could also be achieved with certain technical measures, which would require different site conditions and different economic boundary conditions. With efficiency of 45.9%, this power plant clearly above average of hard coal power plants currently in operation in Germany where average efficiency is around 38%. The study has shown that technically, economically and ecologically optimised power plant technologies based on hard coal provide good opportunities A number of innovative proposals have been included in the plant design. These innovations were selected according to the criteria of their profitability and feasibility using the materials and technologies currently available on the market. This study brings together the planning performance requirements of the plant operators, the planning work undertaken by the plant manufacturers and the results of the academic institutions. The following gives a brief description, details are given in the annexure IV.



5.2 Details of the Study

The first phase of the study involved the collection of innovations and an evaluation. Here innovative ideas in the fields of plant planning, process technology, boilers, mechanical engineering, electrical engineering, instrumentation and control and generators were collected and each individual concept evaluated. The decision on whether to incorporate such an innovation into the reference power plant was taken jointly by plant operators and plant constructors. Parallel to this, the innovation evaluation phase was used to investigate the economic feasibility of the different options of improving efficiency. Evaluation factors such as those for improving efficiency, reducing auxiliary station power requirements and increasing availability have been defined for these studies, based on existing market boundary conditions. Plant operators and plant constructors added their experience to these evaluation factors and together they were used to optimise the plant as a whole. 5.3 Innovations

The study started with a brainstorming phase to gather and evaluate ideas. In total, over eighty innovative concepts relating to plant planning, process engineering, boilers, mechanical engineering, electrical engineering, instrumentation & control, and the generator were raised and their technical and economic feasibility evaluated. The technical concepts were discussed in engineering meetings. The decision as to which of these ideas was to be incorporated in the preferred variant was prepared following a discussion of the findings in the project management group. The following innovative concepts that have been considered in the course of this study should be emphasized in particular:

• With the aim of maximizing power conversion in the turbine and also taking the other economic evaluation factors into account, the exhaust cross-section of the low-pressure turbine section is specified as 16 m2. Because of the high centrifugal forces, the exhaust blades must be made of titanium



alloys. • With the aim of minimizing capital expenditure, various concepts were

studied for installation of the turbine. In the course of this study, a low-level foundation design, i.e. a turbine tabletop at an elevation of around 8 m was compared to conventional design with a tabletop at an elevation of around 16 m. Use of an elevated-level design of foundation for the turbine-generator at 60 m was also considered.

• Standard designs (tower-type and two-pass boilers) were also examined and evaluated, as was the concept of the horizontally fired boiler, the aim being to minimize investment costs.

5.4 Layout Planning

Layout planning was conducted with the aim of designing a compact and efficient plant, using as a basis existing project experience gained from standard reference power plants and hard-coal-fired power plants that have already been built. The in-line arrangement selected for the steam turbine-generator and boiler results in short steam lines and at the same time gives a short length of bus ducting and power transmission line to the outdoor switchyard. This feature minimizes cost. The side-by-side arrangement of the cooling tower and electrostatic precipitator allows efficient design of the flue-gas discharge system via the cooling tower, while achieving optimum routing of the circulating water system at the same time. 5.5 Thermodynamic Design

As part of the optimization process a thermodynamic study was made of the different variants. Below is an overview summarizing the findings:

• Utilization of hot mill air or flue gas waste heat by transferring the heat to the HP feed water-heating line.

• Use of an external de-superheater to increase final feed water temperature up to 320°C.



• Reduction of pressure drop in the extraction lines for the HP feed water heaters.

• Reduction in terminal temperature differences for HP feed water heaters. • Consideration of use of an additional LP feed water heater (9th feed water

heater). • Thermo compression in the area of the LP feed water heaters. • Concepts for reheat temperature control (control within boiler or by spray

attemperation or by allowing reheat temperature to slide). • Consideration of use of an HP feed water heater bypass for mobilization of

short-term peak output. • Study of a feed water pump drive concept (turbine drive vs. electric drives

with various designs). • Optimization of the cold end (LP turbine exhaust cross-section and size of

cooling tower). The power plant concept, which has been optimized for technical and economic factors, produces the following technical data:

• Gross capacity: 600 MW • Type of boiler: Tower-type boiler with vertical tubes and steam coil air

heater • Heat recovery: Utilization of mill air heat recuperation • Flue gas discharge: Discharge via cooling tower • Turbine model: H30-40 / M30-63 / N30-2 x 16 m² • Main steam parameters: 285 bar / 600°C / 620°C • Condenser pressure: 45 mbar • Generator: Water/hydrogen cooling • Feed water heating stages: 8 feed water heaters + external de-superheater • Feed water final temperature: 303.4°C • Feed water pump concept: 3 x 50 % electric motor-driven feed water pumps,

variable-speed drive with planetary gearing In addition to the preferred variant, the following additional requirements for enhancing flexibility have been grouped together in the "flexibility package" option:



• Fast activation of primary frequency control system, as required in the DVG Grid Code "Network and System Rules of the German Transmission System Operators"), 1998 edition.

• Option of providing additional power by partly bypassing the HP feed water heaters and

• Use of header-type HP feed water heater instead of tube-sheet design type. The flexibility package thus takes into account the plant operators' desire to be able to match the power plant’s mode of operation to the requirements of a volatile electricity market, over and beyond straight base load operation. 5.6 Steam Turbine Plant (Turbine, Generator)

The turbine modules used belong to the Siemens steam turbine product line named HMN with best reliability and availability values over the last decades. It is a turboset with separate HP, IP and LP turbine sections. A rigid connection (via so-called push rods) is implemented between the intermediate-pressure outer casing and the low-pressure inner casing. This push rod concept for the HMN series turbine allows thermal axial expansion of the rotor system (moving blades) and that of the casing (stationary blades) to be matched. The result of this is a reduction in the axial clearances for the sealing elements between rotor and casing, and thus an improvement in the efficiency of the turbine-generator. 5.7 High-Pressure Turbine section

As high-pressure turbine the module H30-40 will be used. It’s a barrel-type design best suited for sophisticated steam conditions and assigned power output demand. The inlet parameters for the main steam entering the high-pressure turbine section are 600°C at 285 bar.



The high-pressure turbine section has a barrel-type design. The radial joint is located in the middle of the barrel casing. An HP turbine is equipped with an inner casing due to the high steam parameters of 600°C/285 bar. The HP turbine blading consists of a diagonal stage, which is designed with a low degree of reaction and 17 stages of type 3DSTM (3D design with reduced secondary losses). The entire blading system is designed using the 3DVTM design principle (3DVTM: 3D design with variable stage reaction) so as to optimize blade efficiency. The materials used for the moving and stationary blades are exclusively high-alloy chromium steels with a chromium content of 10 % - 12 %. 5.8 Intermediate-Pressure Turbine section

As intermediate-pressure turbine the module M30-63 will be used. It’s a double flow turbine with inner casing design to cope best with highest reheat temperatures. The inlet parameters for the single-reheat steam entering the IP turbine are 620°C at 60 bar. The model M30-63 IP turbine is a double-flow, dual-shell turbine section. The materials for the shaft and inner casing are high-alloy chromium steels. The outer casing is made of nodular cast iron. This IP turbine module is designed for maximum reheat temperatures. As a outstanding reference the power plant "Isogo", Japan with a reheat temperature of 610°C can be stated. A further increase in reheat temperature to 620°C, affects the creep-rupture strength of the shaft material. The use of a slightly modified alloy content for the 10 % chromium shaft material can increase the material strength. The use of 10 % chromium steel with boron shows promising results. Tests of creep-rupture strength for a shaft-like body are available from a German research project (VGB 158). The results are in alignment with the expected increase of creep rupture strength (time frame > 30,000 hours).



Active, external steam cooling in the steam inlet area is not required. Vortex cooling is used in the inlet flow area. The first blade stage of the IP turbine consists of a diagonal stage, which is designed with a low degree of reaction. At both the generator and turbine ends the blading of the turbine features 18 stages, these including 13 3DSTM blade profiles and four "tapered twisted" profiles. The first three moving blade stages of both flows are fabricated of Nimonic alloys (nickel-based alloys) on account of the high temperatures to which they are exposed. The other moving and stationary blades are fabricated of high-alloy chromium steels with a chromium content of 10 to 12%. In addition, a double T-head design is used for the blade roots of the first and second moving blade stages. This allows the high loading of centrifugal force on the blade roots and root fixing region. The acting centrifugal force is distributed between all blade contact surfaces and thus reduced. 5.9 Low-Pressure Turbine section

The newly developed turbine section N30-2 x 16m2 is planned as the low-pressure turbine section, a double-flow, dual-shell turbine section. The inlet parameters for the crossover steam are 269°C at 5.5 bar. The condenser pressure is 45 mbar. The inner casing features a welded design housing the stationary blade carrier. The low-pressure inner casing rests on the bearing pedestal base plates by means of support arms. The inner casing rests on a sliding plate and can allow axial movements transferred from the intermediate-pressure outer casing by the rigidly connected push rods. The points where the support arms penetrate the low-pressure outer casing are sealed by expansion joints. The LP outer casing and LP inner casing are thus completely decoupled. The N30-2 x 16 m2 features three drum stages and three standard stages per flow. The exhaust cross section of the final stage is 16 m2 per flow. Steel cannot be used to fabricate



this size of blades due to the high centrifugal force loading produced by peak blade speeds of Mach 2. A titanium alloy therefore has to be used. The titanium final stage blades feature a three-dimensional profile with integral shrouding, with a snubber in the middle of the profile. Gap losses at the blade tip are reduced by the integral shrouding. At rated speed the integral shroud and the snubber in the middle of the blade constitute in effect a rigid structure together with the adjacent blades, thereby forming a low-vibration blade assembly. 5.10 Generator Plant

The generator plant consists of a two-pole hydrogen-cooled turbo generator, which is rigidly coupled to the turbine. It has a direct water-cooled stator winding, a static exciter, a two-channel digital automatic voltage regulator and the necessary supply systems i.e. seal oil, hydrogen and primary water units. The stator winding is cooled directly by water, and the rotor is cooled directly by hydrogen. Losses occurring in the other components such as core losses, frictional losses and additional losses are dissipated directly by hydrogen. A large number of radial cooling slots ensure uniform dissipation of heat in the laminated core. The hydrogen is circulated in the closed cooling circuit inside the gas-tight and pressure-proof generator frame by a radial blower fitted at the exciter end. The hydrogen coolers are installed in the generator frame. The water (primary water) treated for cooling the stator winding is circulated in the closed circuit by a pump and transfers the heat absorbed in the primary water cooler to the secondary water. The excitation energy is supplied to the rotor winding by a static exciter via slip rings. The excitation unit consists of an exciter transformer and a thyristor assembly in a three-phase bridge circuit.



5.11 Boilers

Comparison of various boiler designs In order to find the most favorable boiler design for the reference power plant, three different boiler designs were examined. A tower boiler, a two-pass boiler and the innovative horizontally fired boiler were designed and compared with each other in respect of their costs and operational reliability. The aim of establishing specific advantages for each of the types of boiler resulted in different concepts of solution in respect of furnace and the pressure section. MPS mills and low-emission DS burners were used in all variants. The variant comparison is based on a data record for a power plant unit with a gross installed capacity of 550 MW. The fact that in the course of optimising the plant the decision was made that the gross installed capacity of the "preferred variant" would be 600 MW does not affect the conclusions arrived at when comparing the concepts. In order to achieve boiler efficiency of 95%, areas such as the cold end of the flue gas and the furnace were optimised. Innovations in boiler The greatest improvement in efficiency is achieved by raising the steam parameters to the high steam conditions at the boiler outlet (600°C/620°C/292.5 bar). A further improvement in plant efficiency has been achieved by optimizing the economizer section and raising the feed water temperature. These temperature and pressure increases make it necessary to use new material for the walls (7 CrMoVTiB 10 10) and new super heater materials (high-temperature austenitic materials such as TP347HFG). The efficiency of the boiler is improved to 95% by keeping to the very low excess air coefficients of 1.15 and exhaust gas temperatures of 115°C. The distance to the dew point temperature for flue gas ducts and the electrostatic precipitator is achieved by the specified guaranteed coal with a sulphur content of only 0.6%. As a result of the low air ratio and the flue gas temperature window specified by the DENOX plant upstream of the air heater, the air alone is no longer adequate as the only heat sink because a partial flow of cold air must be routed past the air heater on account of the pulveriser mill air



temperature control system. A mill air heat exchanger, one of the innovations, removes the excess heat from the mills’ hot air so that application to the air heater is almost 100%. As a result of transferring this excess heat to the feed water economiser (parallel to the HP preheater section) an exhaust gas temperature of 115°C downstream of the air heater can be achieved. The vertical evaporator tubing in a Benson boiler is a further innovation. The spiral-wound plain tubing is state of the art here, as is a correspondingly high mass flow density to provide adequate cooling of the furnace encompassing walls that are exposed to a high thermal load. The advantages of vertical evaporator tubes pertain more to the design. There is a small advantage as regards auxiliary station power technique since slightly less power is required from the feed pump. From the point of view of production engineering, vertical tubing is easier to manufacture and to assemble. The tie-bars used for the spiral-wound tubing are dispensed with. A flatter angle can be used on the hopper, thus allowing the height of the furnace to be reduced and also generating a cost benefit. The Benson range can be extended to a part load of 20%. This results in advantages when later on the RPP will be operated at intermediate load. The vertical evaporator tubing operates with mass flow densities approximately equivalent to a naturally recirculation boiler. For this reason, optimised inner ribs are required in order to provide adequate cooling. A swirl is created in the flow because of the inner ribs, extending the time the inner walls remain wet. The area of the boiling crisis is thus shifted into zones exposed to less heat flux, thus ensuring that the sudden jump in the temperatures of materials is considerably reduced. Heat flux profiles are largely balanced out as a result of the effect of natural circulation that applies with lower mass flow densities. Where it is known that excess heating occurs, this can be corrected by geometrical adjustments - for instance, larger tubes can be used around the burner. Efficiency can be enhanced further by operating the plant with a variable reheater outlet temperature. In the design point at 100% load, there is no injection during steady-state operation. Although the reheater outlet temperature drops with any movement away from the 100% load point, this proved to be the most economically efficient method for, initially, base-load operation and for when subsequently the plant will be operated at intermediate load.



The partition pitch of 480 mm must also be seen as an innovation. There is no record to date of this kind of spacing becoming blocked. Apart from being able to reduce the height of the boiler by about 1 m, it is also easier to clean by overhead soot blowers. The materials selected for the boiler are:

• Evaporator/superheater - vertical tubing 7CrMoVTiB 10 10 • Superheater 1 support tube partition HCM 12 • Superheater 2 Super 304 H or TP 347 HFG • Superheater 3 HR3C or AC 66 • HP outlet header P92 • Reheater 1 Outlet 7CrMoVTiB 10 10, HCM 12 • Reheater 2 HR3C or AC66 • Reheater outlet header P92

5.12 Water and Steam Cycle

The water/steam cycle essentially consists of the supercritical steam generator, the steam turbine-generator with the condenser, the main condensate pumps, the low-pressure (LP) feed water heaters, the feed water tank, the feed water pumps, the high-pressure (HP) feed water heaters and the connecting pipes. The superheated steam produced in the steam generator is supplied to the turbine which drives the generator. After the steam has driven the HP turbine section and thus released part of its energy, it is passed to the reheater where it is heated up again and then routed to the IP turbine section. The steam flows directly from the IP turbine section to the LP turbine section, where it is expanded to condenser pressure. Finally the steam is condensed in the condenser. The heat of condensation is dissipated via the circulating water system. The condensate produced is collected in the condenser hotwell. The main condensate pumps pump the condensate from there through the LP feed water heaters into the feed



water tank. The feed water pumps are then used to pump the water from the feed water tank through the HP feed water heaters and back to the steam generator. The LP feed water heating line, the feed water tank and the HP feed water heaters are heated with steam extracted from the turbine.

• The condenser is a two-casing surface condenser with water boxes positioned at both sides. The steam dome, steam shell and the hotwell are welded structures, as are the water boxes. The following materials are used: Tubes of stainless steel (14401), tube sheets made of stainless steel (14571). The water boxes are made of Carbon steel.

• Primary frequency control by means of condensate throttling: As the hotwell serves as a condensate storage vessel, there is no need here for an additional cold condensate storage tank.

• 2 x 100 % main condensate pumps: Only one pump operates during normal operation. Following condensate throttling, the second pump is cut in to pump to the feed water tank the condensate that has accumulated in the condenser hotwell in this process. This serves to return the system to its initial status.

• Bypass cleaning of condensate using a separate 1 x 100% capacity condensate cleaning pump: A 2 x 50% capacity bypass cleaning system for condensate is implemented to satisfy the stringent water quality requirements of the Benson boiler for feed water that is low in salt and low in corrosion products. As a result of this configuration, condensate cleaning can be designed for comparatively low pressure levels and the unit can be operated completely independently of the condensate polishing system.

5.13 Cooling Water Systems

The cooling water systems essentially consist of the natural-draft wet cooling tower, the circulating water system with a make-up water supply system, the auxiliary cooling water system and the closed cooling water system.



The circulating water pumps supply the condenser with circulating water from the cooling tower basin. Once the heat of condensation rejected to the condenser has been transferred to the circulating water, this water is routed to the natural-draft wet cooling tower. The heat is ultimately dissipated to the atmosphere via the cooling tower. To ensure the requisite cooling water quality, part of the cooling water is blown down. The system is topped up with make-up water to compensate for losses caused by evaporation and blowdown. The auxiliary cooling water is taken from the circulating water system upstream of the condenser. After it has absorbed the heat from the closed cooling water system, it is returned to the circulating water system downstream of the condenser. The closed cooling water system dissipates the heat from the individual cooling loads via the closed cooling water heat exchanger to the auxiliary cooling water system. 5.14 Technological Options

If the market boundary conditions result in higher economic evaluation factors, this signifies that technical solutions requiring higher specific investments to increase efficiency are then cost-effective. In a marginal case the specific additional investment may exactly match the "economic evaluation factor". If the additional investment is higher, the economics of the entire project are reduced. If additional investment is lower, the projects economics would increase accordingly. Assuming that the economic evaluation factors are higher than in the preferred option, as a result of changing boundary conditions (e.g. CO2 emission costs), the enhancement options summarized might then be of interest. In this context, the preferred option with all its boundary conditions would be the basis for option A. Option A, in turn, would be the basis for option B, etc. Details are shown in Table 5-1 and Figure 5-1 below. Turbine driven boiler feed-water pumps were not investigated, due to the fact that the increase of efficiency in comparison to feed-water pumps with frequency-converter is marginal and the capital cost are much higher than the advantage.



Table 5-1: Preferred option vs. additional options for boosting efficiency

Description Preferred variant Variant A Variant B Variant C Variant D

Specification Basic

Plus frequency Converter BFP

+9 stage preheating +optimized Preheaters

Plus 320oC feed Water end-

Temperature

Plus cond pressure 40 mbar with

LP-Turbine 4×10m2

Plus using of fluegas heat

transfer system with low

temperature- heat transfer

+cond . pressure 35mbar

Live steam parameter

3285bar/600oC/620oC

3285bar/600oC/620oC

3285bar/600oC/620oC

3285bar/600oC/620oC

3285bar/600oC/620oC

Feed water end-

temperature 303.4oC 303.4oC 320oC 320.4oC 320.4oC

Number of preheaters

3HP/FWT/4LP 3HP/FWT/5LP 3HP/FWT/5LP 3HP/FWT/5LP 3HP/FWT/5LP

External desuperheat

er Yes Yes Yes Yes Yes

Steam air heater

Yes Yes Yes Yes Yes

Use of mill air heat

recuperation Yes,HP Preheating Yes, HP Preheating Yes, HP Preheating Yes, HP Preheating Yes, HP Preheating

Sliding reheat

temperature Yes Yes Yes Yes Yes

Condenser pressure

45mbar 45mbar 45mbar 40mbar 35mbar

Low pressure turbine

N30-2×16m2 N30-2×16m2 N30-2×16m2 N30-4×10m2 N30-4×10m2

9..stage preheating

No yes Yes yes yes

Frequency – converter for boiler

feed – water pump (BFB)

drive

No yes Yes yes yes

Feed water end –

temperature 320oC

No no yes yes yes

Condenser pressure 40

mbar No no no yes no


mbar No no no no yes


No no no no no



Description Preferred variant Variant A Variant B Variant C Variant D

mbar Flue gas

heat transfer system with

low temperature

– heat transfer

No no no no yes

Frequency converter

for condensate

- pump

No no no no no

Figure 5-1: Efficiency chart

45.946.1 46.2

46.5

47.3

45

45.5

46

46.5

47

47.5

Preferredvariant***

Variant A Variant B Variant C Variant D

798 Eur/kWApp. 25 EUR/kW

gross per% Point

App. 20 EUR/kW gross

per% Point**

App. 30 EUR/kW gross

per% Point

Above 35 EUR/kW gross

per% Point

Effic iency (%) Vs Evaluation Factor*

Power output for all 600 MW at generator terminals* Increase in efficiency in Eur/kWwgross per % point** The increase of efficiency in varient A considers also reduced aux. power which require additional investment of amount 8 EUR/kW gross *** In the concept study the Preferred Variant was investigated in detail; the Variants A-D have been derived.



"Increase in efficiency" as an economic evaluation factor of the variant under review (e.g. Variant A: 20 €/kWgross per % point) then represents the additional investment that can be justified in economic terms relative to both the gross installed capacity of the power plant and an efficiency increase of 1 % point net. The respective predecessor variant is the basis for each case. For Variant A that would be the preferred variant, for Variant B it would be Variant A and so on. The increase in efficiency of Variant A compared to the preferred variant also includes the efficiency effect that results from a reduction in the auxiliary power requirement (by changing the feed water pump drive). This reduction in the auxiliary power requirement increases the specific investment for Variant A by an additional 8 €/kW (gross) and corresponds to a parallel rise in the "auxiliary power requirement economic evaluation factor". Independently of the measures presented above, a further increase in efficiency to over 47.3 % is possible by further reducing condenser pressure or by increasing the main steam parameters. If the overall concept is changed, by in example considering dual reheat, additional enhancement options are then available. However, all measures require considerable additional investments. 5.15 Summary

The principle challenges of the power supply industry today are security of supply, low-cost generation of electricity, environmental protection and conservation of available resources. This study on the "Reference Power Plant" has been produced with the aim of developing a hard-coal fired power plant concept that is sustainable in the future and will meet these challenges. The main aims of the concept study are to examine the feasibility of a modern power plant with sharply reduced emissions, taking account of the economic conditions that prevail in the deregulated energy market. The first phase of the study involved the collection of innovations and an evaluation. Here innovative ideas in the fields of plant planning, process technology, boilers, mechanical engineering, electrical engineering, instrumentation and control and generators were collected and each individual concept evaluated. The decision on whether to incorporate such an innovation into the reference power plant was taken jointly by plant operators and



plant constructors. Parallel to this, the innovation evaluation phase was used to investigate the economic feasibility of the different options of improving efficiency. Evaluation factors such as those for improving efficiency, reducing auxiliary station power requirements and increasing availability have been defined for these studies, based on existing market boundary conditions. Plant operators and plant constructors added their experience to these evaluation factors and together they were used to optimise the plant as a whole. In this study the power plant concept which is optimized for technical and economic aspects is called the "Preferred variant" and is characterized by the following data:

• Gross installed capacity 600 MW • Net Installed capacity 555 MW • Net efficiency 45.9 % • Main steam parameters 285 bar / 600°C / 620°C • Feed water end temperature 303.4°C • Condenser pressure 45 mbar, wet closed-circuit cooling

via draft cooling tower • Price of the plant 478 mill € • Specific plant price 797 € / kW gross • Boiler type Benson tower boiler with vertical

tubes • Utilization of waste heat Use of mill air heat • Flue gas cleaning SCR-DENOX, electrostatic precipitator,

flue gas desulphurization unit using limestone

• Flue gas discharge Discharge via cooling tower • Steam turbine three-casing steam turbine with

simple intermediate heating and low pressure stages made of titanium alloy

• Generator cooled by water/hydrogen



• Economiser stages Eight economizers + external desuperheater

• Feed water pump concept 3 x 50% electric motor-driven feed water Pumps, variable -speed drive with planetary gearing

The efficiency of the optimum power plant concept "Preferred variant" for the prevailing market conditions is 45.9 %. At less than 800 € gross of installed capacity, the price of the plant is in a range where the RPP is an extremely competitive method of generating energy as compared to the alternatives. The process parameters are crucial for the high efficiency. These include parameters such as high steam pressure and high steam temperatures (285 bar/600°C/620°C), which in certain areas require the use of materials that have only recently been shown to be operationally reliable. As it is practically impossible nowadays to use river water for cooling, closed-circuit cooling via a cooling tower is planned for the reference power plant. The cooling tower is also used to discharge the flue gases produced during combustion. Sulphur and nitrogen are removed from these gases before handling in a separate part of the plant. The standard of flue gas cleaning complies with the strict reference values recently adopted for the European Union. If river water could be used for cooling, it would increase the net efficiency of the plant by a further percentage point to approximately 47 %. Certain technical measures could also be applied to achieve efficiency of over 48 % but these would require different economic boundary conditions than could be assumed at the present time. The effects of double reheating have not been included in this study because the additional investment required would be considerably higher than could be justified by the resulting increased efficiency of about half a percentage point. The efficiency of 45.9 % achieved by the RPP far exceeds the average efficiency currently achieved by hard-coal-fired power plants in Germany. Taking the average efficiency of 38 % (Germany) as a reference point, the increased efficiency of around 8 percentage points reduces the amount of fuel used and consequently also CO2 emissions by around 20 %.



If the power generated in coal-fired power plants in 2020 were only to be generated in plants with efficiency of at least 46%, the CO2 emissions from coal-fired power plants of 9.1 billion t (average efficiency of 34%, worldwide) forecast for 2020 could be reduced by a further 2.3 billion t to 6.8 billion t (average efficiency 46%). The forecast increase of world-wide CO2 emissions attributable to coal-fired power generation in the period between 2000 and 2020 would thus be reduced from 63 % to 21 %. The studies of economic feasibility for this concept show that the RPP is more efficient than all options for hard-coal-fired power plants that are currently being examined in detail, providing that CO2 emissions entitlements do not have a considerable cost impact. The only solutions that are comparable in economic terms in the fossil-fuelled large power plant sector are modern lignite fired power plants (MLP) and combined cycle power plants using natural gas. In terms of economic feasibility, when these two alternative power plants are compared only the modern lignite fired power plant is slightly more cost-effective than the RPP , primarily on account of its extremely low fuel costs, which can also safely be considered to remain at a constant level in real terms over the entire operating period. However, this type of plant can only be operated by companies that have appropriate access to lignite. Nevertheless, this type of plant is extremely relevant to those utilities in terms of covering base-load requirement reliably and cost-effectively in the long term. The time when a plant of the same type as the reference power plant can be used to supply to the grid purely on the basis of commercial decisions depends crucially on the trends that can be expected in the intervening period in respect of the revenues that can be generated on the wholesale market. Currently these are not adequate to justify an investment on business grounds. Overall, the figure for power generation costs based on assumptions made on an individual basis for the new base-load plants that need to be built and which after 17 years will be changed over to intermediate load operation indicate a figure of around 3.3 and 3.5 €ct/kWh. With the planned mode of operation, the RPP is more cost effective than the gas-fired combined-cycle plant, in spite of the considerably higher efficiency of this latter type of



plant and its substantially lower investment costs. The main reason for this is that a hard coal price of 41 €/t (heating value for coal to the design specification = 25 GJ/t, purchase price per tce = 48 €) can be assumed. In view of the very considerable reserves available across the world, the low market access barriers and the market structure characterized by intense competition, hard coal prices will at most increase marginally after being adjusted for inflation over the entire period of operation. This result is comparatively robust because the price of natural gas must not increase by more than 0.5 %/year in real terms in order to make up for the cost advantage of hard coal under these conditions. This is unlikely in view of the increase in demand world-wide for gas as a source of energy and its undeniable environmental advantages, which have been documented in the corresponding asking price. Only if - against all expectations - the price of hard coal were to increase in real terms by more than 1 %/year (and the price of gas did not increase at more than this rate over the same period) would the combined cycle plant produce better economic results than the hard-coal-fired reference power plant. However, these economic advantages only apply if possible cost impacts resulting from measures to reduce CO2 are not taken into account. If the impact of CO2 is only 5 € in real terms per ton of CO2 emitted overall, the hard-coal-fired reference power plant would be considerably less viable economically than the gas-fired combined cycle power plant. The same applies even if the gas price rises by up to 1.2 %/year in real terms and the price increase for hard coal is limited to 0% /year. Thus, apart from the usual market risks, plant operators have to deal with the additional unforeseeable business situations that arise from the political aim of CO2 entitlement trading and the actual national arrangements for this as it affects fossil-fuelled power plants. Coal-fired power plants using the latest designs, which are extremely efficient in terms climate protection and conserving resources, can only be built if the suitable political framework conditions are developed for them. The objectives cannot be met under any circumstances if additional costs for CO2 entitlements were to be loaded onto an efficient hard-coal-fired power plant for reasons of climate protection.



This would only make investment in this technology more difficult and at the same time promote one-sided building of additional gas-fired power plants, with the result that security of supply would be impaired in the long term and dependency on this fuel would lead to increased (price) dependency. In view of the fact that it is expected that hard coal will be extremely significant as an alternative fuel for power generation - on a global scale as well - in the longer term, the successful implementation of the reference power plant in Germany would have considerable export potential, which would contribute to maintaining the expertise of power plant vendors.



6. Role of 700°C Technology for the Carbon-free Power Supply

Dr. Franz Bauer1), Dr. Dariush Hourfar2), Helmut Tschaffon3) 1) VGB PowerTech e.V., Essen

2) E.ON Engineering GmbH, Gelsenkirchen 3) E.ON Energie AG, München

6.1 Introduction and Background

In face of the climate change and the necessary carbon abatement strategy the requirements for the future power supply are carbon-free technologies. Any scenario analysis provided by the IEA Energy Outlook or the publications of the European Commission on this field show the absolute need for carbon-based primary resources for the coming decades. The consequences are the development of carbon-free technologies. The outcome of the Technology Platform ZEP "Zero Emission fossil-fuelled Power Plants" is three major paths for carbon-free technologies:

• post-combustion – capture of CO2 out of the flue gas • pre-combustion – integrated gasification of coal in combination with a CO

shift • oxy-fuel – combustion of fossil fuel under oxygen atmosphere

Clear position of any institution analysing in depth the constraints and opportunities for a carbon free power supply like the TP ZEP or the Eurelectric study ´Role of Electricity´ is that all technological options are needed. Having in mind that climate protection is a global issue the relevance of global competition is evident. As well as the availability of competitive technologies will be decisive for the capability to cope with the challenges and finally to succeed in providing a clean and secure and affordable power supply in the future. The intention of this paper is to point out the strategic role of the 700°C technology, starting with the intention in considering the thermodynamic of the Carnot process and the



materials needed to achieve high process parameters leading to high efficient power plants. It is clearly to emphasize: The 700°C technology is the pre-requisite for the successful implementation of two of the described technology paths - post-combustion and oxy-fuel - based on a high-efficient basic process. Consequently we will deal with the status, the current and coming activities and the perspectives of the 700°C technology. Concerning the overall strategic and political context a position referring the necessity for the coherent regulatory framework and a consistent deployment strategy will be given. 6.2 Status 700°C Technology

The beginning of activities concentrating on the development of materials able to bear 700°C steam parameters lies in the early 90´s, leading to the AD700 project, phase I and II, which were finished end of 2006. AD 700 was co-funded by the European Commission within FP5 launched in 1998 by the Commissioner and supported by about 40 stakeholders from equipment suppliers, power generators and the scientific community. The key objective of AD 700 was the development of innovative turbine and boiler designs, identifying and developing material for the components in the high temperature regions and assessment of the economic viability. A broad range of materials - Ni-based alloys have - been investigated, analysed and tested in small samples. Parallel comprehensive studies have been performed in order to work out a basic power plant concept. The goal was to achieve efficiency figures of more than 50 % net and to give first indications about the economic feasibility of this concept. The necessity of carbon-free technology was not yet on the agenda. The main issue was identification and selection of appropriate materials and testing. The targets set out for the boiler materials with respect to mechanical strength were:



• Martensitic materials 100 N/mm2 at 650 °C/100,000 hours • Austenitic materials 100 N/mm2 at 700 °C/100,000 hours • Nickel-based alloys 100 N/mm2 at 750 °C/100,000 hours

These targets were met for the austenitic materials and the superalloys but not for the martensitic materials. It was not possible to find a better steel type than P92. Sandvik developed the austenitic superheater tube material with the trade name Sanicro 25, and Special Metals developed a superalloy for superheater tubes with the trade name Inconel 740. The nickel-based alloys identified for the boiler and steam lines are materials such as Inconel 617 and Nimonic 263. For the turbine components Inconel 617, 625 and Waspalloy, respectively are foreseen for rotors, castings and blade and bolts. A large number of long term creep tests have been carried out both on bar, tube and forged material, and they are still in progress.

Table 6-1: Composition of AD 700 materials (alloys)

Element

Material

Ni Cr Co Mo Other

A 625 63.5 21.5 0 9 Al, Ti, Nb

A 617 52 22 12 9.5 Al, Ti

A C263 51 20 20 6 Al, Ti

A 740 50 24 20 0.5 Al, Ti, Nm

Sanicro 25 (A 174) 25 22 1.5 0 W, Cu, Fe

The result of both phases of AD 700 was a preference set of materials covering all requirements for boiler materials consisting of membrane wall, headers, pipe-work and valves and for turbine materials with shaft, blades, pipe-work and valves. As important as the material development was the outcome of the plant concept studies demonstrating the principal possibility of both – high efficiency and promising cost figures.



In the following the key issues are presented. The thermodynamic of the Carnot process with relevance for the plant concept is shown in Figure 6-1. Figure 6-1: Carnot efficiency and efficiencies of some seawater-cooled plants



Consequently the thermodynamic scheme for 700°C concept is described in Figure 6-2. Figure 6-2: AD 700 thermodynamic cycle

As the nickel-based alloys are extremely expensive, the concept of compact design was studied. The aim is to minimize the amount of these materials – e.g. by making the steam lines as short as possible. These studies identified considerable room for savings, which also will be valuable for more conventional plants. For the turbine, a turbine inlet valve, forged rotor, welded rotor, moving blades, stationary blades, bolting and welding of pressure containment parts were considered. Also innovative designs with the aim of reduced need for the nickel-based alloys have been studied. Considerable effort has been made to establish business plans for a full-scale demonstration plant. The studies included a detailed risk assessment and again a check on the feasibility taking the latest material strength values and prices into consideration. The technology is still feasible even when a moderate price for CO2 quotas is used.



Parallel national projects have been initiated, particularly MARCKO I and II covering both material design and tests in small samples. Emax Initiative Based on these encouraging results of AD 700 an industry funded strategy study was started with the goal to make a comprehensive evaluation in general and to define the steps necessary to bring this technology to real application under market conditions. The work was done under the umbrella of the Emax Initiative - an industry group driven by the generators coordinated by VGB. The clear result was the confirmation that this concept offers the potential to cover both high efficiency and the fundamental basis for a carbon-free power supply on fossil fuels and before entering into the erection of a demo plant two steps are stringently needed:

• a component test under realistic operation conditions with the experience of design and fabrication of the near full scale components and

• out of this learning process a pre-engineering study for the specifications for a demo plant covering material concept, design and fabrication, balance of plant consisting of process figures necessary for 50% efficiency, component design and operation requirements.

At the end one will get reliable figures in terms of actions to be done, the realistic time schedule and the financial means needed for realisation – ready for a sound assessment of the contribution for a carbon abatement strategy, of the market opportunities, of the funding requirements - public and industry - and the time and cost risks aligned with. 6.3 Current and Coming Activities of the 700°C Technology

COMTES700 First step of the study was the design, construction, erection and operation of the component test facility (CTF) COMTES 700; i.e. a facility implemented into an operating boiler consisting the key components of a boiler like evaporator membrane wall, superheater, pipe-work, headers and valves, additionally with a turbine control valve and



referring ducts. Due to the fact that under FP a continuation in terms of funding was not possible the resources of the Research Fund for Coal and Steel were taken, an occasion to thank for the co-operative support of the DG RTD. The project has been co-ordinated by VGB integrating partners from the equipment suppliers and the generators, i.e. 9 European generators are working together in terms of financing and exchanging experience and pursuing this technology with the goal of implementation in due time. The work started in spring 2004, the component test facility went into operation in July 2005 and until now more than 10.000 operating hours could be achieved. The CTF represented a considerable challenge. The principle diagram may look relatively simple, but the integration in the power plant with all necessary steam-, drain-, vent lines, instrumentation and control equipment represent a really big task, which in this case was made even bigger because the time from the official start to actual operation was only one year and delivery times for the tube and pipe material were long. E.ON has been responsible for the integration and operation of COMTES700 in Scholven F (see Figure 6-3). Figure 6-3: Principle diagram COMTES700



Generally one can state that the learning process was very interesting, but very useful and has given clear indications what has to be analysed and investigated within the pre-engineering study as the next step. Parallel to COMTES700 a test rig in the Esbjerg power plant was installed with a certain precursor function, meaning testing in advance design and material as a kind of accelerating process and to take preventive measures. PP 700 – pre-engineering study The project has been conceived as a cross-border transnational project. To date, 10 European energy utilities (E.ON Energie AG, Electricité de France, France, Electrabel European Generation, Belgium, EnBW Kraftwerke AG, Germany, EVN AG, Austria, DONG Energy Generation, Denmark, RWE Power AG, Germany, STEAG AG, Germany, Vattenfall Europe Mining & Generation AG & Co. KG, Germany, Vattenfall A/S Nordic Generation, Denmark) have joined together with the aim of developing this sustainable European concept for generating power on the basis of fossil fuels. In the context of the envisaged pre-engineering study the European energy utilities involved will determine viable technical and economic decision-making principles for power plants with a live steam condition of 700°C. The European Generators are working together supported by a European regional fund (local government of the State of North Rhine-Westphalia) in pursuing the issue of pre-engineering. The equipment suppliers are integrated by orders placed by VGB the co-ordinator. Goal is to perform an innovative pre-engineering study in order to be ready for a more detailed evaluation of the opportunities of the technology at the end. The necessity and political will of a convincing carbon abatement strategy is on the agenda now. In the mean time the TP ZEP was launched strongly developed and pushed by the stakeholders from the electric power industry lead by VGB. The work of the pre-engineering study has started and is terminated for autumn of 2008 - an exciting time is lying ahead.



6.4 Perspectives of the 700°C Technology

As stated before the necessity for a CO2 free power supply technology is on the political agenda; having in mind the results of the scenario analysis from IEA and EC DG TREN postulating a major share of power supply will be on fossil resources - there is no other way if security of supply and competitiveness are taken into account. The technological development of fossil-fired power plants, with a marked increase in efficiency levels to around 50 %, is at the forefront. In the phase of power plant renewal in the medium term, i.e. in the years from around 2015 to 2020, it could thus be ensured if the project is concluded successfully that the European CO2 reduction targets can be achieved by means of efficient, economically viable power plant solutions. A reduction in specific CO2 emissions per MWh generated of around 25 % compared with power plants currently in operation (mean efficiency 38 %) is associated with 700°C technology. The proportional reduction in the fuel mass flow used can also partly offset rising fuel prices. The competitiveness of the European energy industry and also of the capital goods industry that is to be supplied with electricity and process heat can thus be stabilized. In the long term, i.e. in the new construction period after 2020, the realization and safe operation of a power plant using 700°C technology represents together with other technologies like Oxyfuel and IGCC an essential prerequisite for flushing CO2 economically out of the flue gases and transferring it to suitable deposits. E.ON has announced to build and to operate a demonstration plant based on the 700°C technology. This is an important step towards carbon free technologies. The power output was fixed in the before mentioned pre-engineering study with 550 MW gross. The process will be a single reheat cycle. E.ON plans to erect the demo plant in the northern part of Germany. The operation is scheduled for 2014. To realise this ambitious plan a lot of additional R&D work has to be done. Only to mention one example: It´s necessary to produce reheat pipes out of Alloy 617 with an outer diameter of about 500 mm and a wall thickness of 30 mm. A COORETEC associated project with participation of VGB, several German electric utilities and manufacturers was launched in this year to produce a longitudinal welded pipe. In the beginning of 2008 the pipe will be produced. Afterwards the pipe will be examined and a creep test follows.



6.5 Regulatory and Political Framework

The 700°C technology is of even higher relevance than before. Two paths out of three major routes are requesting a high-efficient basic plant concept respectively highly efficient components in order to master the technical challenge of resource saving, carbon capturing and affordable generation technologies. This can be provided by the 700°C technology. The key characteristics of the post-combustion process as well the oxy-fuel process are components demanding process heat in form of steam or water or flue gas. In spite of the fact that for determining exact figures intensive research work has to be done. But the first results are showing very clearly that only by a high temperature thermodynamic cycle combined with an optimal integration of the additional steps of carbon capture out of the flue gas - post-combustion - or air separation for delivering oxygen for the combustion - oxy-fuel - the goal of a resource saving carbon-free power supply at affordable costs can be achieved. Efficiency of any process step is the key for success. Another important opportunity of the 700°C technology is the one for synergies; synergies in a sense that the key characteristics of components of different power plant concepts are based on the same principles of laws of nature. The design, the construction, the test and the operation of components - even for a specific concept - delivers worthwhile results for other concept using the physical or chemical processes. By respecting and supporting this effect a more efficient and successful development of new power plant concept will be ensured - the key argument for pursuing different promising power plant concept in parallel. This helps essentially to reduce the unavoidable risks of technical development. The strategic context is determined by the following facts:

• Evidence of climate change • Access to primary resources • Worldwide competition and • Necessity to develop Carbon-free technologies for fossil based plants.



The consequences for the European Union, but the other global players also are to find the right political measures respectively regulatory framework in order to enable to develop the appropriate technologies in due time with the available resources - human and financial one. The supply with energy or power is at the end a question with a huge social background even potential for explosive stresses. The past and the evident future challenge has shown that it is necessary to reflect on the

• goal and approach for public funded research programme • balance between basic and industrial research and application • relation between public and industry funded research and development and • role of political and regulatory framework.

It is time now to intensify a broad and open discussion between all involved parties now with the aim to draw coherent conclusions and to initiate a stringent action plan. The initiative of the European Commission to establish a Strategic Energy Technology Plan, SET plan, has been appreciated. At the end huge investments have to done, but investments are only possible if a level playing field is in place covering the above-mentioned topics.



7. Road Map to High Efficiency Power Plant

Efficiency refers in this context not only to the choice of the power plant process and its parameters, but also to operation and maintenance and the efficiencies attained in daily operation. The planning, construction and project handling for such power plants also must be efficient if the projects are to be successful. Finally, the term "efficiency" as applied to net efficiency must be regarded in relation to the power plant efficiencies possible and attainable in each country. The high-efficiency power plant by itself or as an element of Carbon capture and storage (CCS) schemes represents an important contribution to the conservation of fuel resources, but also to climate protection. The European Road to build high efficiency power plants is given in the annexure V, exemplarily Evonik Steag.



8. Technology Platform for Zero Emission Power Plants by 2020

Following developments in clean power generation and the priority given to "zero emission power generation" in the Sixth Framework Programme (FP6) industrial stakeholders and the research community had several meetings which resulted in the creation of a technology platform for zero emission fossil fuel power plants. The strategic deployment document and the strategic research agenda as well as more details are given in annexures VI(a) and VI(b). The Experts agree that CO2 capture and storage technology (CCS), together with improved energy conversion efficiency, is a near-term solution to reducing CO2 emissions from fossil fuel power generation on a massive scale. Its immediate deployment is therefore vital if we are to avoid the catastrophic consequences of climate change we are facing today. Yet despite most of the technology elements being available, CCS is still not deployed for two key reasons:

1. The costs and risks still outweigh the commercial benefits 2. The regulatory framework for CO2 storage is not sufficiently defined.

The Strategic Research Agenda therefore describes a collaborative programme of technology development for reducing the costs and risks of deployment; while the Strategic Deployment Document outlines how we can accelerate the market to achieve zero emission power production by 2020.



PART II 9. Definition of Efficiency Parameters - Basics

9.1 Efficiency

There are different ways of describing the efficiency of a combustion installation. There are also a number of national guidelines describing acceptance tests and the measurements of certain efficiencies. The efficiencies defined in this report as well as in the annexures to this report are to be understood as efficiencies at a certain electrical output and normal operating mode, i.e. as the power station is operated in daily generation mode. They are calculated from averaged measured values attained from the values recorded over a certain period of time. This section gives the brief details of various types of efficiencies dealing with the power plants and other related parameters such as:

• Carnot efficiency: The ideal efficiency of a thermal process or ‘Carnot’ efficiency is a measure of the quality of the conversion of heat into work

• thermal efficiency: thermal efficiency considers only the actual cycle process used in the power station. The efficiency is then the ratio of the useful mechanical output to the heat flow transferred to the cycle process media (as a rule, air or water)

• the degree of fuel efficiency: The degree of fuel efficiency is defined for cogeneration plants, which generate and emit electrical and thermal energy (heat). For these plants, the useful output consists of the sum of the generated electrical energy and the generated thermal energy

• proportional auxiliary station service • high voltage net capacity • heat consumption of generating unit • overall efficiency of power plant • fuel consumption



• specific fuel consumption • unit efficiency: Unit efficiency is then the ratio of the net electrical output to

the energy supplied with the fuel. The electrical output according to this definition is the output on the high voltage side of the main transformer.

• unit efficiency for steam withdrawal: If, in a power station unit, steam is extracted for heating or process purposes, then this steam is no longer available for power generation. In order to be able to compare the unit efficiency in this case with the efficiency of pure power generation, the electrical output which could be obtained from the extracted heating steam if it were to expand to the condenser pressure, has to be added to the electrical output.

• exergy concept and exergy efficiency • influence of climate conditions on efficiency • relationship between efficiency and environmental issues

Details on this are given in annexure VII. 9.2 Losses of Efficiency in Combustion Plants

The heat energy resulting from the combustion of fossil fuels is transferred to the working medium (steam). During this process, part of the energy is lost in the flue-gas. The total losses from the generation of steam depend on the fuel (ash and water content, calorific value); the capacity and operation of the steam generator; the air-fuel mix; the final temperature of the flue gas; and the mode of operation. The operation of the steam generator requires continuous surveillance. The heat losses from the steam generator can be categorised as:

• losses via the off-gas. These depend on the flue-gas temperature, air mix, fuel composition and the level of fouling of the boiler

• losses through unburned fuel, the chemical energy of which is not converted. Incomplete combustion causes CO and hydrocarbons to occur in the flue-gas



• losses through unburned material in the residues, such as carbon in bottom and fly ash

• losses via the bottom and fly ash from a DBB and the slag and fly ash from a WBB

• losses through conduction and radiation. These mainly depend on the quality of insulation of the steam generator.

In addition to the heat losses, the energy consumption needed for the operation of auxiliary machinery (fuel transport equipment, coal mills, pumps and fans, ash removal systems, cleaning of the heating surfaces, etc.) also has to be taken into consideration. Poor combustion lowers the economic viability, increases the environmental impacts and is detrimental to the safety of the plant. The following parameters affect the viability of the plant and may, therefore, be monitored to keep the plant’s efficiency as high as possible:

• fuel composition • fineness of grind • flue-gas composition (O2, CO2, CO) • air mix and flue-gas volume flow • air leaking into the combustor • boiler fouling • temperatures of the combustion air and flue-gases • temperature behaviour within the heating surfaces • reduction of draught • flame profile • combustible proportion of residue (annealing loss)

9.3 Generic Technical Measures to improve Large Combustion Plant's Efficiency

9.3.1 Combustion

The fuel is mixed with air and burned in the boiler. It is not possible to obtain an ideal mix between the fuel and air, and therefore, more air than is necessary for stoichiometric



combustion is supplied to the boiler. Furthermore, a small percentage of the fuel does not fully combust. The flue-gas temperature must be kept high enough to prevent condensation of acid substances on the heating surfaces. 9.3.2 Unburned Carbon in Ash

Optimisation of the combustion leads to less unburned carbon-in-ash. It should be noted that NOX abatement technologies using combustion modification (primary measures) show a tendency of increased unburned carbon. Increased unburned carbon could also worsen and harm the quality of the coal fly ash and make it difficult, or even prevent, their utilisation for certain applications, with the risk that they may not comply with the specifications and requirements laid down in relevant national and European standards. 9.3.3 Air Excess

The amount of excess air used depends on the type of boiler and on the nature of the fuel. Typically, 12 – 20 % excess air is used for a pulverised coal-fired boiler with a dry bottom. For reasons of combustion quality (related to CO and unburned carbon formation), and for corrosion and safety reasons (e.g. risk of explosion in the boiler) it is often not possible to reduce the excess air levels further. 9.3.4 Steam

The most important factors in increasing efficiency are the highest possible temperature and pressure of the working medium. In modern plants the partially expended steam is reheated by one or more reheating stages.



9.3.5 Flue-Gas Temperature

The flue-gas temperature leaving the clean boiler (depends on the fuel type) is traditionally between 120°C and 170°C, due to risks of acid corrosion by the condensation of sulphuric acid. However, some designs sometimes incorporate a second stage of air heaters to lower this temperature below 100°C, but with special claddings on the air heater and the stack, which makes this reduction economically unprofitable. By power plants designed without stacks, the flue-gas temperature is between 65 and 70°C. 9.3.6 Vacuum in the Condenser

After leaving the low-pressure section of the steam turbine, the steam is condensed in condensers and the heat released into the cooling water. In order to ensure the maximum pressure drop over the steam turbines, it is desirable to reduce the vacuum to a minimum. In general, the temperature of the cooling water dictates the vacuum, which is lower with once-through cooling systems than with a cooling tower. The best electrical efficiency is possible by seawater or fresh water-cooling and a condenser-pressure with approximately 3.0 kPa. The preferred option is to use seawater or river water if this available. 9.3.7 Variable Pressure and fixed Pressure Operation

In fixed pressure operations, the pressure before the turbines at all load levels is kept more or less constant by changes in the flow cross-section at the turbine inlet. In variable pressure operations with the turbine inlet cross-section at its maximum, the power output is regulated by changes in the pressure before the turbines.



9.3.8 Condensate and Feed-Water Preheating

The condensate coming out of the condenser and the boiler feed-water are heated by steam to just under the saturation temperature of the extracted steam. The thermal energy from the condensing process thus feeds back into the system, reducing the amount of heat otherwise released from the condenser, therefore improving the efficiency. The optimisation measures taken to improve the efficiency of power plants between 1993 and 2000 which resulted in a CO2 reduction of 11.0 million tonnes per year as shown below:

Steam generator 39 % Process optimization 14 % Turbine 25 % Auxiliary power 14 %

The reduction of emissions from large combustion plants can be carried out in different ways.



10. Energy Balance

Following figure shows an energy flow chart (Sankey diagram) of the individual losses within the heat flow of a condensation power plant. Figure 10-1: Sankey diagram of individual losses

Energy flow in a 200 MW power unit, layout des ign:

Mass flow live steam ( sm& ) 167.8 kg/s; 245 bar/520 °C

First intermediate superheating 78.5 bar/530 °C Second intermediate superheating 22 bar/540 °C Condenser pressure approx. 0.0235 bar Feed water end preheating 303.6 °C (nine preheater stages) a) Flue gas – air preheating H) Circulation losses (water and steam) b) Feed water preheating I) Turbine losses c) Fresh air K) Thermodynamic cycle (water & steam) d) Make-up water L) Losses of generator e) Feed pump turbo set M) Auxiliary consumption, overall A) Fuel energy input N) Auxiliary consumption of the turbine installation B) Losses due to radiation and unburnt material O) Auxiliary consumption of the steam generators C) Exhaust gas loss P) Steam generator output D) Ash losses Q) Turbine output E) Pipe losses R) Generator output F) Loss of the feed pump turbo set S) Effective useful output G) Heat loss of the preheating installation



When analysing the efficiency of conventional power plants, it must be taken into account that the fuel costs amount to approximately 75 % of the total average production costs, which clearly shows the necessity of operating the plant at optimum efficiencies. Not only cost-effectiveness is required, but also the reduction of the emission of air-polluting substances by saving fuel. 10.1 Efficiency of German Power Plants

Efficiencies in German power plants vary widely and keep increasing due to enhancements of the power plant technology. At present, the data summarised in the following Table 10-1 can be assumed.

Table 10-1: Efficiency of German Power Plants

Net electrical efficiencies in % Power plant type

Current optimum values

Target values

Natural gas and steam power plant with condensation 55 – 58 60

Fossil fuel steam power plant with condensation 40 – 48 50

Natural gas turbine power plant 30 – 36 40

Closely connected to the efficiency of a condensation power plant are the process losses, also called cooling water losses or condensation losses. For physical reasons it is impossible to avoid them in a condensation power plant. They are the biggest losses and therefore strongly reduce the power plant efficiency. They are determined by the type of steam power cycle:

1. the design of the water-steam circuit (e.g. with or without intermediate superheating)

2. the pressures and temperatures of the live steam and superheated steam



3. the cooling water temperature and, connected to it, the condensation pressure

4. main condensate and feed water pre-heating One practical solution for the exact determination of the losses or efficiencies is to monitor the heat output and the generated effective output (kW). The heat capacity (kJ/s, MJ/s) is the heat input into the process for a certain time unit. 10.2 Efficiency Degradation

The degradation of the plant efficiency is a normal process, but a permanent challenge to minimise the degree of degradation. State of the art of plant operation and maintenance is to keep the degradation level between the ranges of +/- 0.1 % net efficiency. This impressive figure is the outcome of a well equipped plant in terms of monitoring and cleaning system. The major components of the monitoring system are stress gauges, temperatures measuring and vibration control devices and software tools to calculate heat balance, frequency analysis etc.: The major cleaning systems are water conditioning, condenser cleaning and soot blowing systems. The backbone of these systems is a state of the art process control & instrumentation system allowing the record of any relevant data. The targeted systems respectively indicators are heat transfer decrease in the boiler caused by ash deposits, heat transfer decrease in the condenser caused by fouling effects, air control of the boiler island, avoidance of corrosion in the boiler and pipe system by the well suited operation of the Electrostatic Precipitator and last but not least the turbine island – vibration and frequency control. 10.3 Energy Balance of a Coal-Fired Power Plant Unit

As an example, two energy balances are drawn up for a German coal-fired power plant with a useful output of 830 MW. In one case the steam generator forms the balance limit,



in the other one it is the boiler house. The energy balances were drawn up by means of measured values, which were found in a field test for the determination of the unit heat consumption. During the measurements, 100% of the combustion air was taken from the boiler house (internal suction) at a temperature of 55°C. Preheating of the combustion air in relation to the ambient air amounted to 45°C, which corresponds to a heat quantity of 18.5 MW. Yet the radiation and pipe losses at the steam generator according to DIN EN 12952-15 amount to only 2.43 MW. The examination of the supplied heat flows for both energy balances shows a difference of 15.5 MW. This difference is based on the difference between the actual radiation and pipe losses and the radiation and pipe losses as determined according to DIN EN 12952-15. This means that the choice of different balance limits leads to differing at the time of calculating the heat flow input of the fuel heat input. These differences directly influence the calculation of the boiler efficiency and the unit efficiency, where the error amounts to approximately 0.5 % points for the unit efficiency. The radiation and pipe losses of the respective steam generators are included as lump-sum figures in the "indirect method" according to DIN EN 12952-15, depending on the maximum useful heat output. As the measurement results of the different coal-fired power plant units show, the amounts of losses determined that way do not correspond to the actual radiation and pipe losses of the steam generators. If this method is applied in practice, the following consequences result from it:

• Especially for steam generators operated with internal suction, it is not possible to draw up conclusive balance limits. For heating up the combustion air within the steam generation building, the amount of "recovered" energy is much bigger than that which is radiated by the boiler according to the current regulations.

• The choice of different balance limits around the steam generator leads to differences in the calculation of the fuel heat input. The deviations resulting from this directly affect the unit efficiency.



Figure 10-2: Energy balance for the steam generator

Boiler house

(QSt+QV)back = 15,5 MW

tL,env = 10,0 °C tsupply = 25,0 °C tL,sb = 55,0 °CmLhL = -6,0 MW mLhL = 12,5 MW QSt,tot = 13,5 MW

QV = 3,0 MW

Pfan = 3,0 MW QN,sb = 831,0 MW

Pcomill = 2,0 MW Pcomill = 2,0 MW QA = 53,0 MW

mB(Hu+hB) = 891,0 MW mB(Hu+hB) = 891,0 MW QS,F = 8,0 MW

-6,0 MW 12,5 MW 13,5 MW

+ 3,0 MW + 831,0 MW+ 2,0 MW + 2,0 MW + 53,0 MW+ 891,0 MW + 891,0 MW + 8,0 MW

total 890,0 MW total 905,5 MW total 905,5 MW

91,77%93,03%

supplied heat flows supplied heat flows dissipated heat flows

Efficiency, limit of balance steam generatorEfficiency, limit of balance boiler house

Steam generator

10.4 Operating efficiency in European Power Plants

The following Figure 10-3, Figure 10-4 and Figure 10-5 show the attainable efficiency of power plants and comparison of various technologies such as IGCC, super critical, nuclear, gas turbine etc in addition to technology perspectives and incremental efficiency improvement in power plants.



Figure 10-3: Comparison of efficiency of various types of power plants (Source VGB)

Figure 10-4: Technology perspective in terms of efficiency (Source VGB)



Figure 10-5: Efficiency improvement of coal fired boilers (Source VGB)

The efficiencies are evaluated based on the following formula:

NCVasInputEnergykWhNetEfficiency =

The complexity of thermal power plant efficiencies reporting in India and Germany are given in annexure VIII. The various formulas used for estimation of thermal power plants are given below:



10.5 Operating Efficiency of typical Indian Power Plants compared to German Power Plants

The following gives the variation in efficiency figures due to evaluation criteria for a typical Indian power plant of 500 MW. Basis for calculation (typical design values)

• Gross rating of the plant 500.15 MW • Turbine gross heat rate 1944.6 kcal/kWh • Auxiliary power 8.00 % • Auxiliary power 40.012 MW • Net power output 460.138 MW • Coal consumption 278.5 t/h • Coal GCV 4,000 kcal/kg • Coal NCV 3,758 kcal/kg

Coal analysis

• Fixed carbon 28 % • Volatile matter 22 % • Moisture 20 % • Ash 30 %

The efficiencies, as described in chapter 10.4 could be determined as follows:

• Efficiency # 1 (based on net kWh & GCV) 35.52% • Efficiency # 2 (based net kWh & NCV) 37.81 % • Efficiency # 3 (based on gross kWh & GCV) 38.61% • Efficiency # 4 (based on gross kWh/NCV) 41.10%

For comparison the typical efficiency of German power plant is given to

• Gross rating of the plant 500 MW



• Turbine gross heat rate 1,944.6 kcal/kWh • Auxiliary power 10.80 % • Auxiliary power 54 MW • Net power output 446 MW • Coal consumption 189.7 t/h • Coal GCV 5,615 kcal/kg • Coal NCV 5,386 kcal/kg

The efficiencies, as described in chapter 10.4 could be determined as follows:

• Efficiency # 1 (based on Net kWh & GCV) 36.01 % • Efficiency # 2 (based Net kWh & NCV) 37.54 % • Efficiency # 3 (based on Gross kWh & GCV) 40.37 % • Efficiency # 4 (based on Gross kWh/NCV) 42.09 %

10.6 Comparison of published efficiencies

Comparison of published efficiency values for different types of power plant is difficult for several reasons:

• Differences in the calculation of the heating value of the fuel • Differences in site conditions and especially condenser pressure • Differences in plant design, such as single or double stage reheat at

otherwise a similar plant design • Consideration of gross or net efficiencies (and plant output), use of add-on

equipment such as for example a flue gas desulphurisation The condenser pressure is commonly the most important factor, and going from a condenser pressure of 0.05 bar, which requires a cooling water temperature of 27-28°C, to 0.02 bar, with a cooling water temperature of 14-15ºC, produces an extra three percentage points. Thus, for proper comparisons, all actual plant efficiencies ought to be recalculated to 'standard conditions' in order to be meaningful.



In Europe, efficiencies are expressed on the basis of lower heating value (LHV), which is the difference between the higher heating value (HHV which is the total amount of energy contained in the fuel) and the latent heat of evaporation of the water contained in the products of combustion. In Europe, evaluating efficiency by considering the LHV is considered accurate assessment of the 'useful' energy of the fuel for plant where this water goes to the atmosphere in the flue gas stream. The ratio of HHV to LHV depends on coal composition and its heat content. For fuels such as natural gas and biomass with higher hydrogen content, this ratio will be much higher. This complicates comparisons between different technologies and fuels. When generating efficiencies are quoted as based on HHV, the electricity output is divided by the HHV of the fuel used. When they are quoted on an LHV basis, the output is instead divided by the LHV value of the fuel. Consequently, HHV generating efficiencies are lower than LHV generating efficiencies. For example, a coal-fired steam plant with an HHV efficiency of 40% has an LHV efficiency of approximately 42 %, provided plant design and site conditions are the same. A broad understanding of the current status of coal-based power plant can be gained from a comparison of several state-of-the-art steam plants around the world, as illustrated below (Table 10-2): Table 10-2: Differences in efficiency based on HHV and LHV

(Source: www.berr.gov.uk/files/file30703.pdf)



The Japanese and US plants have relatively high condenser pressures compared to the Danish plant. The Niederaussem plant burns a lower grade lignite, whereas the others are fuelled with bituminous 'trading' coals.



11. Key parameters and basis for measurements

11.1 Key operating parameters

Coal fired power plants built are based on the proven and fully developed engineering. The major key operating parameters of power plants are main steam pressure, main steam pressure and condenser vacuum. The hard coal fired power plants, designed for net efficiency in the region of 45%. The following table (Table 11-1) shows the development of boiler efficiency based on the improvement in main steam pressures and temperatures along with related operating parameters. Table 11-1: Development of boiler efficiency based on improvement in steam pressures,

temperatures and other parameters

Parameter Unit # 1 # 2 # 3 # 4 # 5 # 6 # 7 # 8 # 9 Efficiency % 41.0 41.2 41.5 41.6 42.5 42.6 42.8 43.7 44.3

Improvement % 0 0.5 0.8 0.25 2.0 0.3 0.5 2.0 1.3 Main steam pressure

bar 250 250 250 250 250 300 300 300 300

Feed water temperature

°C 260 280 280 280 280 280 300 300 300

Main steam temperature

°C 530 530 540 540 540 540 540 580 580

Reheater steam temperature

°C 540 540 560 560 560 560 560 600 600

Condenser pressure

bar 0.047 0.047 0.047 0.047 0.047 0.047 0.047 0.047 0.04

Exhaust gas temperature

°C 130 130 125 125 125 125 125 125 125

It can be seen that the efficiency is raised as steam pressures and temperatures are raised while the flue gas exhaust temperature and condenser vacuum lowered. Similarly, the following table (Table 11-2) gives the parameters for lignite based power plants. Table 11-2: Typical boilers operating parameters

Parameter Dim. Neurath Schwarze Boxberg Lippen Niederaussem



Unit E Pumpe dorf Unit K Efficiency % 35.5 40.6 41.7 42.3 45.2 Improvement in efficiency % 14.4 2.7 1.4 6.9 Main steam pressure bar 165 262 266 267 269 Feed water temperature ° C 235 274 270 295 Main steam temperature ° C 525 547 545 554 580 Reheater temperature ° C 525 565 581 583 600 Condenser pressure bar 0.66 0.035/0.046 0.041 0.038 0.028/0.034

In addition to the above the following Table 11-3 summarizes key operating parameters of different power plants in Europe. Table 11-3: Key operating parameters of the power plants in Europe

11.2 Fuel Parameter

Coal is a natural product. For this reasons its chemical, physical and technological properties depend on the herbal starting substances and the geometrical conditions during carbonisation. The knowledge of chemical, physical and technological properties of coal is of utmost importance for its use as fuel in combustion plants. A German Standard, DIN 51700, defines the most important analysis procedures for the uniform description of properties of solid fuels. To assess the coal, a distinction is made between the pit coal as delivered and the water



and ash-free substance (waf). The moisture and ash-free substance contains only the burnable parts of the solid and volatile elements. Prerequisite for smooth operation are the knowledge of and information about these characteristics and properties. The following overview shows the most important characteristics:

• Calorific value • Ash content • Water content • Volatile elements • Sulphur content • Elementary analysis of the ash • Melting behaviour of the ash • Mineral size fraction of the pit coal • Composition of the mixture • Elementary analysis of the coal • Apparent weight • Grinding fineness of the pulverised fuel • Grindability of the coal

The details of the above listed characteristics are given in annexure IX. 11.3 Air & Flue Gas Parameters

The detailed parameters under this category need to be measured/monitored are given as well in the annexure IX. To determine the individual efficiency, the following parameters have to be measured in individual systems: electrical power, pressure, temperature, mass flow, differential pressure and oxygen content. When the measuring data are determined, wear, pollution and leakages have to be taken into account; at least they should be documented. 11.4 Data required

The data required for assessing the effeminacy, output, performance etc given in the



annexure IX.

• Table 1: Parameters required for efficiency determination by energy balance method (Source ASME PTC 4)

• Table 2: Parameters required for efficiency determination by input- output method

• Table 3: Parameter required for capacity determination • Table 4: Parameters required for steam temperature /control range

determination • Table 5: Parameters required for excess air determination • Table 6: Parameters required for water / steam pressure drop

determination • Table 7: Parameters required for air / flue gas pressure drop

determination • Table 8: Parameters required for air infiltration determination • Table 9: Parameters required for fuel, air and flue gas flow determination



12. Official Statistics for Efficiency Indicator and Plant Reliability

Each member state of the European Union is obliged to deliver statistical data. The energy sector takes an essential part in the statistics. Special focus is laid on plant efficiency and plant reliability. Special investigations are often made in order to allow an in depth analysis of specific topics. An example is the report of the EU Joint Research Centre, JRC. In addition to the basics the analysis and tools are essential elements to judge a power plant process and appraise it in the whole complexity. With this knowledge and the fact that the single component or single systems have to be measured prepared can a basic measurement be accomplished. But at first specific data are essential. To furnish single countries in Europe, and the very different regions over there, with energy, it is important to be aware of a few facts about the development, afforded power amount and coal consumption. The details about the common technical processes, general fuel heat conversion in boilers, typical elements of a steam cycle are given in annexure X. 12.1 Reports on Analysis and Tools for Efficiency Indicators

Based on the selected and described indicators samples for standard reports used in the EU are given. These official reports are published by national authorities as well as

1. Eurostat (the Statistical Office of the EU), "Energy, Transport and Environment Indicators" http://epp.eurostat.ec.europa.eu/portal/page?_pageid=0,1136052&_dad=portal&_schema=PORTAL

2. EU Joint Research Centre, "Reference Document on Best Available Techniques for Energy Efficiency", and download possible under http://eippcb.jrc.es/pages/FActivities.htm (scroll down to "Energy Efficiency" and download the draft document)



12.2 Excerpts from Eurostat-Document

As official statistics Eurostat has published newest energy indicators for example on energy intensity, gross inland consumption per capita et al. The extracts are given in the annexure XI.



13. Performance Indicators & Monitoring

13.1 Introduction

In the liberalized energy market the evaluation of the performance of an own power plant compared to other power pants (benchmarking) is of great importance. To optimise the performance of a power plant in competition:

• the compilation of availability data and evaluation of performance indicators and

• the comparison of indicators of a single plant with the indicators of peer groups

are strategic tools for many VGB-member-companies. In performance indicators and monitoring of the power plants VGB is very active and is collecting data and information from members' power plants since 1970. The data provide the information about the availability and utilisation of the thermal power plants in order to compare the quality of the power plants and to assess plants behaviour in daily operation. The basic tasks involved in the performance monitoring are

• Collecting of power plant performance indicators with the help of the VGB online power plant information system KISSY (KISSY is power plant information system which include collection and evaluation of performance indicators) As these as these strategic tools were of great importance for power plant operators during the last thirty years the hitherto used old dBase related tool was replaced by a new modern online-power-plant-information-system KISSY, which is discussed more in detail. With the aid of KISSY, benchmarking can be carried out efficiently.

• Determination of conventions for the publication of performance data of power plants

• Preparation of availability- and unavailability reports



• Definition of new performance indicators for comparative assessment of the performance of power plants in the liberalized power market

• Management of road shows for performance indicators and power plant benchmarks

• Appropriate guideline updating The major parameters monitored for performance of power plants in Europe are:

• Time availability • Energy availability • Time utilisation • Energy utilisation • Start-up reliability

Time availability The time availability is the quotient of the available time and the reference period (calendar time). The available time is the difference between the reference period and the unavailable time.

N

vt t

tk =

Dimension

tk Time availability h

vt Available time h

Nt Reference Period h

Energy Availability The energy availability is the quotient of the available energy and the nominal energy. The available energy is the difference between the nominal energy and the unavailable energy. The nominal energy is the product of the nominal capacity and the reference period (calendar time).



N

vW W

Wk =

NN

vNw tP

WWk⋅

=−

Dimension

Wk Energy availability -

vW Unavailable energy MWh

NW Nominal energy MWh

NP Nominal capacity MWel

Nt Reference Period h

Time utilisation The time utilization is the quotient of the operating time and the reference period (calendar time). The time utilization is a measure for the real temporal use of a plant. It is independent of the level of the corresponding operating capacity.

N

Bt t

tn =

Dimension

tn Time utilisation -

Bt Operating time h

Nt Reference period h

Energy utilisation The energy utilization is the quotient of the energy generated and the nominal energy. The nominal energy is the product of the nominal capacity and the reference period (calendar time). The energy generated is the product of operating capacity and operating time (numerator).



The energy utilization is a measure for the energy, which a plant has really generated. Frequently used are also the equivalent definitions "utilization duration" or "full load utilization hours" The correlation between energy utilization and utilization duration

N

Bw W

Wn = = NN

B

tPW⋅

N

BN P

Wt = = Nw tn ⋅

Dimension

wn Energy utilisation -

BW Energy generated MWh

NW Nominal energy MWh

NP Nominal capacity MWel

Nt Reference period h

Start-up reliability The start-up reliability is the quotient of the number of successful start-ups (se) and the sum of successful (se) and unsuccessful start-ups (sn). The start-up reliability is used for the evaluation of units whose service life depends essentially on the number of start-ups, e.g. gas turbines, emergency aggregates.

ne

e

sssz+

=

Dimension

z Start-up reliability -

es Number of successful start-ups -

ns Number of unsuccessful start-ups -



Classification of unavailability (NV) Planned unavailability: The beginning and duration of the unavailability have to be determined more than 4 weeks before commencement. Unplanned unavailability: The beginning of unavailability cannot be postponed or only up to 4 weeks. Post-ponable unavailability: The beginning of unavailability can be postponed more than 12 hours up to 4 weeks. Not post-ponable unavailability: The beginning of unavailability cannot be postponed or only up to 12 hours. These performance indicators are also basics of any benchmarking approaches (see chapter 15).



14. Software and Analytical Tools for Efficiency and Plant Reliability –Online and Offline

14.1 Introduction

The cost pressures in the power generation business force the power plant operators to take specific measures to improve the operating efficiency and reduce cost. Intelligent evaluation of existing in-service measured data using online and off line analytical tools is one efficient way to recognize the current potential for optimisation by assessing the processes and components. The benefits of online & offline software analytical tools are

• enhance the efficiency of your power plant operation, • arrive at maximum electric output that can be generated at the moment

taking into account operational and technical constraints • computation of ratios and key figures (efficiencies, electric energy from

cogeneration, start up cost, etc.) • comparison of performance indicators • component evaluation (steam generator, heat recovery steam generator,

steam/gas turbine, steam- water cycle, condenser, pumps, flue gas circuit, etc.) for optimum and efficient operation

• optimisation (example: soot-blowing, gas turbine compressor washing, cold end, etc.)

• forecast (unit efficiency, maximum unit output, etc.) • measured-data reconciliation featuring neuronal plausibility checking • central alarm-signalling service system • individual "what if" process simulation • closed-loop operation • Individual daily, monthly reports, statistics • diagnosis and analysis • several others



14.2 Software Analytical Tools / Modules

Several software analytical modules are available in EU, which are specifically designed for power plant for plant monitoring and optimisation. The typical systems, which are predominant in EU, are:

• General statistics for official use • Specific industry driven data collection and compilation tools • Systems for optimum operation (Which cover energy management systems /

plant optimisation system /system services/systems integration – all in a single module package or individual modules)

• Lifetime monitoring system • Data management system -including subprograms • Thermodynamic cycle calculation program – offline monitoring system

The above systems can be installed separately or as a combination with others. The details of these systems are given below: 14.3 Data Collection for the Performance Monitoring

For detailed analysis required data pertain to the above parameters from the power plants are collected very meticulously by VGB: More than 471 power plants across Europe is covered. The data were considered will be fed to the KISSY for the detailed analysis and review. The performance monitoring is carried out by data collection for various types of power plants such as:

• Fossil-fired units • Nuclear power plants • Combined cycle units • Gas turbine units • Capacity type



Until 99 MW 100-199 MW 200-399 MW 400-500 MW 600 and above All units

• Fuel type by capacity Bituminous coal fired units Lignite fired units Oil /Gas fired units

• Furnace type by capacity Bituminous coal fired units with dry bottom firing Bituminous coal fired units with slap top firing

• Units by single or dual boilers • Units by subcritical or supercritical pressure

The above units will be considered as total Europe, in addition the entire exercise will also be carried out for Germany Units. 14.4 Analysis for Performance Monitoring

The analysis covers about 217 power plants for the operating period po1997 to 2006. The information analysed for various parameters such as:

• Failure with out damage • Damage • Check/condition check • Lubrication • Maintenance • Inspection\ • Preventive maintenance • Cleaning • Revision



• Refuelling • Reconstruction/refurbishment • Test/functional tests • Official test/measure • Other incidents

The above analysis is carried out for unavailability incidents per block and year and also for energy unavailability. The analysis will also include on equipment basis such as:

• Power transmission • Distribution of solid fuels • Pressure system, feed water and steam sections • Support structure, enclosure, steam generator interior • Ash and slag removal, particulate removal • Bunker, feeder and pulverising systems • Main firing system • Combustion air system (primary and secondary) • Flue gas exhaust • Chemical flue gas treatment system including residual removal • Feed water system • Steam system • Steam turbine plant • Generator plant • Circulating water system

14.5 K I S S Y

KISSY is Power-Plant-Information-System is a relational data base system on an oracle platform. It currently covers availability data and performance indicators of over 9760 unit years of German and other European power plants. Every full member of VGB can feed data to KISSY data base and at any time read the complete data of his own power plants online



via internet. The relevant availability data and performance indicators, which have to be collected and analysed for benchmarking are defined and explained in VGB-guidelines. The new kind of operating power plants initiated by the liberalised market requires the consideration of further performance indicators as for instance

• indicators for commercial availability • damage- and condition-oriented indicators

which will be incorporated with the next planned enhancement of KISSY. Every full member of VGB which wants to feed availability data can get access to the KISSY database. Members will get username and password by VGB. Then they can feed, change and read data for their own power plants online via a secure access (SSL-encryption). Data of other power plants are not visible to them via internet. The System will guide on, which availability data and which data for reporting unavailability incidents have to be collected. Additionally the basic data of the power plant units (see attachment E) have to be fed once into the database by VGB in order to assign the units to their peer groups for analysis and reporting. The analysis of the anonymous data is done for peer groups by VGB. The data fed by members via internet into the KISSY data base will be transformed anonymous by VGB and related to peer groups for benchmarking. Peer groups cover data of power plants with similar characteristic attributes which therefore can be compared (anonymously) with respect to their performance. Main peer groups for standard reports are:

• fossil-fired units • nuclear units



• combined cycle units • gas turbine units

Arranged by:

• capacity • fuel • type of firing • single/dual boiler • sub- / supercritical

Analysis is done for:

• time availability • time utilization • energy availability • energy unavailability • energy utilization

All members, which feed data into the KISSY data base get for free the standard reports for the above mentioned peer groups with analysis of key figures of availability and unavailability of components (for the previous 10-years period) annually. Current reports are available for downloading on VGB`s website within a closed user group area for VGB-members only. These reports will be updated every 3 months. For other parties the standard reports are available at VGB Power Tech Services. The detailed procedure in using KISSY is given in annexure XII. 14.6 Systems for Optimized Operation

These are online tools to cover energy management systems / plant optimisation system / system services/systems integration.



These online analytical tools continuously assess plant operation, comparing it with a current calculated optimum so that the unit can be run at maximum efficiency. These tools are normally based on a three-tiered concept – evaluation, optimisation and forecast for cost-relevant power plant sections. Potential for optimisation is indicated, and even minimal reductions in efficiency are pinpointed. All results are evaluated at cost so that the effects of different operating parameters can be directly compared. The most important task of the plant optimisation system is to monitor the current plant operation and to compare it with the currently possible optimum on a continuous basis. The calculations needed for this are executed automatically on the basis of the current mean values of this time class. The results are saved in the related time archive in the Data Management System and can thus be visualized in the same way as all other data. Two different concepts are followed for the plant diagnosis is

• The optimisation of the plant operation and • The monitoring of the components or parameters.

For further details please refer to annexure XXII. A. Plant Optimisation Systems The plant optimisation system combines and presents thermodynamic models of the Plant components with economic parameters, specifically variable operation costs, to determine the current deviation between actual and the corresponding optimum plant operation. The thermodynamic modelling takes into account limiting constraints of operation. The plant optimisation also includes an off line manual (what if) analysis tool that enables the user to conduct model-based analysis of plant operation. Plant optimisation system includes the following:

• Thermal cycle optimisation. This computes the entire turbine and regenerative cycle heat balance and simulates the plant so that operator can examine the improvements in heat rate and can change individual cycle parameter.



• Computes the boiler efficiency and simulates boiler parameters such that operator can examine the improvements in boiler efficiency.

• Boiler tube life fractions and stress calculations. The features of standard graphical representation of the complete package based on Process Flow Diagram and the P&ID are included. The graphic screen is developed in order to enable that the user to conduct model-based analysis of Plant operation and get the results in an understandable manner. The tool includes all required drawings and graphical representation of the total plant system covers all equipment and drives related to the Optimisation package. Process graphic displays will be developed by the power plant operator to have a complete overview of the package indicating the display of equipment of boiler and turbine auxiliaries. The dynamic data is clearly being indicated such that the operator need not refer to multiple diagrams to assess system operation. Arbitrary continuation break points between displays are not used in such systems. B. Functional Requirements The plant optimisation functions are based on model-based software. The system computes controllable losses related to plant parameters not being maintained at their design points based on actual loads. The model is also including option to identify equipment cleanliness for various heat transfer sections within the plant. The optimisation software also identifies the actual sequence of soot blowing so that costs of heat loss due to unclean heat transfer sections and the costs of soot blowing can be minimized. Typical Plant Optimisation System will perform the following functional requirements. C. Boiler Stage Optimisation The system incorporates complete thermal design. This provides a continuous on-line, cost-benefit assessment of where and when i.e., the actual sequence, to blow soot from individual boiler stage surface areas. The boiler optimisation calculations take into account the following factors:



• Main steam conditions • Hot reheat conditions • Fuel inlet conditions • Ambient air conditions • Soot blowing usage • Gas exit temperature • Leakage of air pre-heater • Boiler efficiency • Heat rate

With boiler optimisation model, operators can obtain a ranking of cost/benefit of soot blowing on monitored boiler stages. The boiler optimisation model will be developed for the following sections: -

• Economizer • Water walls • Super heaters • Reheaters • Air heaters

The radiative heat transfers, convective heat transfers and heat & mass balance equations are used to generate the above models. High degree of boiler cleanliness shall thus be ensured. D. Soot Blowing Optimisation Soot blowing optimisation advises operators to clean boiler stages at appropriate time and location to optimise soot-blowing operation. The high quality boiler calculation advises the operator judicious soot blowing of boiler stages. The boiler cycle monitoring calculations provide the following results: -

• Cleanliness factors on boiler stages • Furnace exit gas temperature • Flue gas temperatures between boiler stages



• Actual heat transfer coefficients for each boiler stages • Theoretical heat transfer coefficients for each boiler stages • Flue gas cross-flow velocities • Stage heat absorption • Stage average metal temperatures • Specific heat of both air and gas • Excess air • Stage cross flow velocities

Normally a suitable combustion model will be included in the software. E. Thermal Cycle Optimisation This module computes the entire turbine and regenerative cycle heat balance and simulates the section of the plant so that operator can examine the improvements in heat rate attainable by changing a cycle parameter. The turbine and regeneration cycle is modelled such that any change of boiler parameters can be examined in relation to the overall heat rate of the plant for what if-scenarios. The turbine optimisation model is normally developed for the following sections: -

1. Turbine HP/IP/LP 2. Condenser 3. Deaerator 4. Feed water heaters 5. Pumps (Condensate, Boiler feed)

For turbine performance optimisation standards such as ASME PTC6 "Enthalpy Drop" efficiency calculations for determining turbine efficiency will be applied. In monitoring turbine cycle performance the following parameters are calculated:

• Main steam flow • Reheat flow • Condenser steam flow



• Turbine stage flow • Individual turbine stage efficiencies • Overall HP, IP, LP turbine efficiencies • Turbine calculated wheel power • Turbine calculated exhaust enthalpies • Turbine calculated exhaust velocities • Cold reheat steam approach to saturation temperature • Superheat spray outlet approach to saturation temperature • Expansion line end point at condenser pressure • Used energy end point

The power plant personnel provides component degradation tool package, which evaluates heat rate and cost effect of the components detailed below. The calculable losses identify the losses associated with equipment degradation and those associated with non-maintenance of design parameters independently.

• HP Turbine, IP Turbine, LP Turbine • Feed Water Heaters, • Condenser • Boiler Feed Pumps • Deaerator • Boiler • Turbine Extraction line • Condensate pumps • Heat Exchanger

In these packages, the turbine stages are considered as long as the steam is still dry at the respective outlet. Since the tools contain a thermodynamic model of the process, losses of the generator cannot be determined. For the same reason steam seal regulators cannot be modelled. However, if necessary, the leakage through the steam seal may be considered as boundary condition. In addition, overall system degradation can be evaluated. Graphical presentation of results will be furnished as a part of the optimisation guides provided to the operator. These will



be in the form of bar charts, X-Y plots, and plant mimics. Predictive and diagnostic tools package is adopted in the form of ‘What if’ for diagnosing plant degradation. Those included in the ‘What if’ analysis are the following items, which can be modified by the user to see the effects on plant generation, heat rate and boiler efficiency: -

• Throttle pressure • Throttle temperature • Reheat temperature • Condenser backpressure • Superheat spray flow • Reheat spray flow • Final feed water temperature • Boiler excess air • Flue gas exit temperature • Heater bypass • Feed water flow • Boiler feed pump efficiency • Boiler feed pump discharge pressure • Feed water heater terminal temperature differences • Feed water heater drain cooler approach • Turbine stage efficiencies • Condenser cleanliness factors • Condenser circulating water inlet temperature • Circulating water flow • Fuel ultimate analysis and heat content • Fuel firing rate • Boiler stage cleanliness factors • Gas re-circulation and tempering • Unburned carbon • Bottom ash and top ash removal • Air heater leakage • Ambient air condition



This package can also be used to evaluate the effects of the following:

• Changing operating conditions and load • Comparing test data to best attainable and evaluating the results after ASME

correction • Changing boiler stage geometry to evaluate the effects on steam and exit

temperatures 14.7 Lifetime Monitoring System

The basic objectives of this type of tool are:

• Improved maintenance planning • Faster connection to grid • Better exploitation of material

Components of power plants exposed to high temperatures and pressures suffer serious material degradation during their lifetime. The appearance of the first cracks in the material indicates the need for component exchange or at least its repair. The degradation originates either from creep of the material caused by pressure induced stress or from fatigue caused by fluctuations of temperature and pressure in the component wall. Under certain stress conditions material creep increases strongly with temperature and decreases with wall thickness. On the other hand fatigue due to temperature induced stress increases with wall thickness. During the design of the component both types of stress are taken into account, leading to an optimum compromise in accordance with the respective design rules. Because the actual plant operation deviates more or less from design conditions, the accumulated material degradation is not proportional to operating time; that is why a regular monitoring of plant operation is recommended. The best way to carry out such monitoring is by continuously operating a data logger together with a data evaluation system. The Lifetime monitoring software system continuously records operating temperatures and pressures around all critical components of a power plant and from that calculate the



resulting contributions due to creep and fatigue. Thus the operator is kept well informed about the current status of the plant, especially about the remaining lifetime of the vital components. The mathematical algorithms follow the European standards. The systematic and continuous application of tool reduces the cost for routine maintenance inspections as well as additional tests. Because degradation of component parts is a long-time effect, it is permissible and, in case of malfunction, not avoidable that from time to time component degradation increases disproportionately. However, the operator should keep in mind that disproportionate degradation increases must be compensated by way of plant operation generating less than proportionate degradation increases, if the planned components lifetimes shall be maintained. Therefore, using SR1 the operator has an instrument suitable for well-aimed influencing the remaining lifetime at his disposal. For example, if the live steam temperature is willingly increased within the admissible range to improve the unit’s heat rate, the corresponding higher creep damage at least partly consumes the free margin possibly accumulated during previous operation, or the planned remaining operation time must be reduced. Analogously, by willingly shortening the start-up time of a boiler – thus saving start-up costs and connecting to the grid faster –increased lifetime consumption due to cyclic fatigue will be recorded. Accordingly the accumulated free margin will be reduced. The respective allowable curves are specific for each component. These curves will be adjusted automatically to the operation pattern recorded in the past. This dynamic adaptation provides the operator with a clear indication on the permissible operations for each monitored component. This type of tools can be employed successfully in many different power plant units either as stand-alone application or in combination with other modules like data reconciliation or optimisation of power plant operation. Normally such systems are designed to run on Windows NT as a client/server system. It includes a specific data management systems as well as a powerful visualisation module. The required data are exchanged with the process control system or with external data management systems via standard interfaces. For system handling and visualisation of



calculation results on the customer owned LAN/WAN licence free clients in any number are available. 14.8 Data Management System

The central component of all online systems is the data management system. In annexure XXII a detailed description of the important features of such system is provided. The essential task of this tool is the cyclic import and archiving of measurement values from the control system or from other data sources. Other data sources can be bus systems or online databases. A corresponding interface is provided for each type of data exchange. All other tools installed access this data through an internal interface, evaluate this data and save the results. This tool enables the automatic integration of data to higher time classes. The data is read by default in minute-cycles and integrated internally to 5’-mean values. All the optimisation calculations are done in this time class. Other integration levels are, for example, 15’-values, hourly values, daily values, weekly values, monthly values and yearly values. According to the respective system configuration, these or even other time classes are available. The entire data is saved in the related time-oriented archives. The system has subprograms for visualizing the archived data or for configuring the data management system. The data visualization enables the representation of any time series in diagrams as well as the representation of a point of time in a flow diagram. Diagrams can represent a maximum of 24 data points in up to 6 ordinates. The displayed time period as well as the time class (minute values or daily values, etc) can be selected freely. Along with the chronological display, ordered output curves or x-y-diagrams can also be selected. Along with line charts, bar charts are also possible. Special events or violations of limiting values can be signalled in the flow diagrams through automatic display of texts or through a corresponding colouring.



14.9 Thermodynamic Cycle Calculation Program – Offline Tool

All the optimisation and evaluation calculations described above require a detailed thermodynamic model of the boiler and of the corresponding power plant process. This model is configured graphically with the help of the Cycle Calculation Program. This can be as offline tool. This tool provides a lot of components of power plants, which not only permit the modelling of the entire water-steam cycle, but also the detailed modelling of the steam generator. Similarly, essential components of the air and flue gas path can also be included in the modelling. Depending on the respective monitoring or optimisation task the required details of the model can be adjusted accordingly. This means that the boiler can be represented by an individual component within the water-steam cycle or it can be constructed from the main components heating surfaces, injections, combustion chamber as well as the connecting pipes. The water-steam cycle itself is constructed from the main components turbine, condenser, pre-heater and pumps as well as the connecting pipes. Especially the turbines are typically modelled as a combination of the individual turbine stages. This tool is a powerful tool to help the Power Plants/define areas of inefficiency component wise and total plant as a whole. The entire plant is first "mapped" by the Software to establish consistency of online data and compare with design parameters of the plant. The outcome of this exercise give a complete mapping of Power Plant configuration including equipment specification into a software that can simulate certain conditions and identify partial mismatches as well as wrong instrumentation display data. The power plant provides the data, which is used to do the mapping of the Power Plant. The Power Plant is mapped based on data input and validate data input by trial runs. This approach is interactive since initial power plant data provided will usually not match due to hidden or known instrumentation errors as well as inaccurate equipment and fuel specification. The objective is to demonstrate more innovative methods to conduct a baseline



performance assessment and map the results into software for further analysis and simulation for the benefit of the plant operators. This professional software is a mass and energy balance cycle calculation program – highly integrated into Windows. It is suitable for nearly all-stationary thermodynamic model requests coming out of energy cycles or plant schemes. The mathematical kernel of EBSILON is well known for its extreme convergence stability and for the high calculation velocity (see also annexure XXII). Not at least the last reason for several customers to use software is the user-friendliness which is ensured by 100 % Microsoft-conform, intuitive handling. Therefore it is – for this purpose – the most used software at several small and large companies as nearly a lot of manufacturers and utility companies in the German speaking Europe. Such software program is fully available also in English and French and there are customers in Netherlands, Poland, and Denmark and in China. The modelling is done by using a component library, which in the moment exists of all components as e.g. turbines, heat exchangers, boiler, pumps, generators, gas turbines, combustion chambers, tanks, gasifier, FBC, fuel cell, cooling towers dryer, filters, separators, fans, control elements, calculation modules, text fields, buttons, alarm fields etc. A customer programmable component allows by the use of C-knowledge the fully integration of self generated components. First the cycle is modelled topologically by using the component toolbox and the positioned components are then parameterized. All components are equipped with sets of default values. he sets are taken from a library, which can be modified and enlarged by the user. From this library also total and parts of cycles are eligible. Also a gas turbine library is available. For media properties different tables are available. Fuels (bituminous coal, lignite, gas, oil, hydrogen, biomass etc.) can also be used from a library. Flue gases etc. are nearly unlimited elementary definable or selectable from default compositions. This professional tool is so powerful that in one model also several power plants may be connected by power lines or steam and a district heating system still in a high detail can be calculated in one



model in some seconds. The Import and Export of data and results is possible via variety of Excel or ASCII interfaces as via DLL. All adjustments as visualization topics, physical dimensions (or British Units), are components dependent or general (also or fly) eligible. A very comfortable error analysis tool leads the user through this model to the error source. Beside exists a calculable example for every component as an online documentation for general questions. Figure 14-1: Typical mapping of a power plant



In principle, this software does not restrict the detailing depth of the modelling. The characteristic lines or the characteristic fields for describing the thermodynamic behaviour of the individual components are determined on the basis of the design calculations or by evaluating the measurement values. In this way, the characteristics of the components for the entire load range can be determined. Typical mapping carried out by such typical software is given below (Figure 14-1).



15. Benchmarking of Power Plant Operation & Management

15.1 General

Re-organisation of the power industry has progressed and has put pressure on heat and power production cost with the import of electricity from neighboring regions possible. In this context, many power plants have taken up several mid-term programs of efficiency and competitiveness improvement (strategic cost management program). A competitive power generation might only be reached by cost cutting what means technically and cost efficient power and heat generation. In thermal power plants the following subjects are preconditions for this:

• low operation cost • low maintenance cost • high technical efficiency in plant operation • effective management organization • compliance with surrounding regulations.

Benchmarking of power plant involves development of essential technical and organizational elements for the long-term commercial sustainability of the power plant operation. 15.2 Basics of Benchmarking

The competitive energy market in EU demands that power generation companies must have a critical look on their business policy. "Benchmarking" provides a chance to compare a company, a plant or a production unit with another or a "Best Practice"-company, plant or unit, to find out its own ranking in a competitive market. The own position in the competitive market will be given by means of indicators, which will be defined at the beginning of the process.



Measures for a better economical efficiency of the company / power plant / unit focused on, are to be derived from the results. For example "cost/kWinstalled" is such an indicator in the power sector (Figure 15-1). Figure 15-1: Finding out a position in a competitive market by Benchmarking

What is benchmarking?Why do we need benchmarking?

Comparison of ........ .......... a process or a company with other competing processesor companies with specific indicators(cost, €/kWi in thermal and hydro power plants or WMO in hydro power plants)

Ranking....................... of your own company in the market

What?

Why?

Conclusions and development of measures

15.3 Benchmarking of Thermal Power Plants

The total cost will be divided into different groups of cost (Figure 15-2) and then analyzed and compared with other, similar power plants. The greatest attention will turn on the total operating cost. Numerous measures to improve efficiency and production cost have to be elaborated, evaluated, compared and finally best options need to be introduced. This gives the



advantage to judge benchmark key indicators versus the background of practical operations. Figure 15-2: In thermal power plants the focus of the analysis is on cost of operation

Fuel cost€/kWh

Capital cost€/kWinstalled

Administrativecost

€/kWinstalled

Total operating cost

€/kWinstalled

Maintenance€/kWinstalled

Operation€/kWinstalled

Other€/kWinstalled

Total cost€/kWh

Focus of

analysis

15.4 Benchmarking Methodology

It is useful to conduct at first an internal and secondly an international Benchmarking to compare these units and to show their ranking compared to the international market. After this analysis the experts can point out cost intensive areas of operation. Measures to realise a cost effective operation of the analyzed power plants will be elaborated in an initial stage and can be suggested to the plants. The benchmarking exercise consists of a pre-phase and additional three project phases (Figure 15-3).



Figure 15-3: Phases in a successful Benchmarking process

Data collection

Determination of potential for

efficiency increase

Drawing up of measures and

creation of scheme of

implementation

Implementation

Development of concept to increase efficiency Implementation

Phase I Phase II Phase III Phase IV

Introduction to methodology

and selection ofsubjects tobenchmark

Pre-Phase

In Phase I an extensive and detailed data collection on the subjects to be considered will be performed. This data collection will build the essential basis for all following phases. In the following Phase II the technical and organizational performance will be compared in a way that the determination of potential for efficiency increase will be possible. Following this in a Phase III there will be the focus on drawing up a strategic concept to improve technical efficiency and establish a cost efficient operation. Phase IV encompasses the realization and the implementation of measures and is not part of this proposal. Pre-Phase Introduction to the methodology of benchmarking processes It is very important to get acceptance and support for the Benchmarking process on all levels of power plant, because data acquisition, identification of potential improvements and first of all realization of measures to improve need to be accepted by all stakeholders



within the company. Therefore, a team representing top level and working level of Power plant should be created to work on this process. A steering committee is required to take decisions according to the timetable of the project. All parties need to get a general understanding of the process and will be introduced to the methodology of Benchmarking. Phase I: Comprehensive technical economical, administrative and organizational data collection By means of an extensive and detailed data collection in this Phase I the basis for the comparison of technical and organizational performance as well as for the definition of goals and the development of measures in the following phases will be provided (Figure 15-4). Figure 15-4: Overview data collection

Data sheetsData sheetsOther (insurance, etc.)Other (insurance, etc.)

Purchasing / Materials managementPurchasing / Materials management

Organisation / ProcessesOrganisation / Processes

EmployeesEmployees

CostCost

Technical dataTechnical data

Basic data site

• installed capacity

• number of units

• generation

• specific technical features

• ...

Basic data site

• installed capacity

• number of units

• generation

• specific technical features

• ...

Reference year: Last year

A comprehensive datacollection …….

1a. Fuel (TPP)1b. Scheduling (HPP)2. Operation3. Maintenance4. Administration

… is the basis for a comparison of cost for a sucessful benchmarking

A comprehensive datacollection …….

1a. Fuel (TPP)1b. Scheduling (HPP)2. Operation3. Maintenance4. Administration

… is the basis for a comparison of cost for a sucessful benchmarking

Data collected and evaluated will include (e.g.):

• fuel supply in TPP • process organization (structure, cost, etc.) • management organization (hierarchical structure, cost, etc.)



• technical and economical data on power generation (operation and maintenance, overhauls, degree of automation, etc.)

• administrative data (overhead, personnel, etc.). For a basic year of investigation as well as from following years available data will be taken into account. Total operating cost will be divided into various cost components such as operation cost, maintenance cost and other cost (see chapter 15.3 and Figure 15-2). Maintenance cost themselves will be divided into cost for routine maintenance (cover cost for regular maintenance and other repair expenses) and cost for maintenance projects (cover cost for inspections and scheduled overhauls, cost for individual measures and cost for other measures). Depending on the maintenance cycle annual maintenance cost may vary more or less. It is important to determine a representative mean value for the basic year, preferably the running year. Concentrate on technical issues and consider their economic influence including the following topics:

• Heat and power production efficiency (production equipment efficiency) • Heat supply systems efficiency (efficiency of the heat supply infrastructure) • Fuel supply efficiency (fuel purchase and storage efficiency) • Material and technical supply efficiency (material and technical resources

purchase and storage efficiency). At the end of Phase I the data collected will be presented to the Client and, if required, additional information input from the Client will be discussed. Phase II: Determination of potential for efficiency increase The methodology of Phase II for thermal power and heat generating plants is described below. The results where an efficiency increase seems to be successful and feasible in short term as well as in long-term measures will be presented to the Client at the end of Phase II.



The data collected in Phase I will be evaluated and key performance indicators and site-specific correction factors will be elaborated and defined. The site-specific correction factors will be discussed with the responsible power plant personnel. Correction factors are essential to compare power plants. They will be introduced to adjust location and type of a power plant. Site correction factors e.g. consider different levels of wages, different annual working hours or different cost of materials. Correction factors for technical differences will be determined in a multi-step elaboration. Important parameters of the power plant will be determined; by analysis and discussions with the local experts the correction factors will be set up. In addition to general technical differences, other peculiarities having influence on the power plant cost will be considered. Based on the data a comparable gap will be defined, including the international comparable gaps for both units. Results of the comparison will show the power plant’s / unit’s ranking with respect to the category it is operating in. This comparison will be made with international power stations. By comparison with the "Best-Practice" power plants / units savings potential for the power generation units under consideration will be determined and the data assessment of the current situation will allow the definition and suggestion of cost saving measures in Phase III. The collected but non-corrected data do not show differences in cost or efficiency against other power plants. Only the introduction of correction factors allows the demonstration of advantages or disadvantages of the power plant considered versus international power plants. In Figure 15-5 the potential for improvements worth striving for is outlined.



Figure 15-5: Evaluation of correction factors in thermal power plants

Power Plant 1 Power Plant 2

Power generatingcosts

Power generatingcosts

Operation Operation

Capital

AdministrationAdministration

Capital

Fuel Fuel

To compare power plants, corrective factors need to be applied to make adjustments for sites / power plants types.

Data collection

Data comparison

Data correction

Benchmark

Definition ofgoals

Developmentof measures

Realisation of measures

Figure 15-6: The value of a benchmarking project is not the contest but performance

improvement opportunities

PP 1non corrected

data

corrections PP 1corrected data

Best Practice

potentialfor

improvements

disadvantageversus

best practise PP

advantagesversus

best practise PPimprovements

worth striving for

PP 1non corrected

data

corrections PP 1corrected data

Best Practice

potentialfor

improvements

disadvantageversus

best practise PP

advantagesversus

best practise PPimprovements

worth striving for



Phase III: Drawing up of measures and creation of scheme of implementation During Phase III first draft measures are drawn up and suggested in the process. The implementation of these measures will be schematically described. Technical, organizational and economic measures to increase the efficiency and saving costs will be developed, suggested and discussed with the management of the power plant branch management and the company management. Points of start, where first measures could be introduced will be found out. The measures elaborated and the implementation scheme will be presented to the Client. After the specific cost reduction measures for the thermal power plants are identified and the required level of investigation for each measure is known, the Consultant will prepare a separate tender for the related services. 15.5 Project Organization

A successful co-operation between Consultant’s and plant's experts is a precondition to elaborate immediate measures, which will lead to comparatively quick results. It is required to establish one project team guided by a steering committee. Plant engineers will be the local engineering partners to the team. The responsible plant and administrative personnel will join the teams, each for the different topics (typical organization (Figure 15-7), and support the benchmarking team. By this the detailed knowledge on the thermal heat and power generating plants is going to be combined with external experience in efficient power plant operation in the liberalized energy market according to the state of the art. To ensure an overall evaluation concerning administrative, management and economic assets, experts will closely work together, exchange their information and discuss the analyses with their power plant's counterparts.



Figure 15-7: Typical project organization for a benchmarking process

Steering CommitteeSteering Committee

Member of the BoardPower Plant DirectorEvonik Energy Services

Member of the BoardPower Plant DirectorEvonik Energy Services

Project DirectorProject Director

N. N. (Power Plant)N. N. (Evonik Energy Services)N. N. (Power Plant)N. N. (Evonik Energy Services)

Core Team MaintenanceCore Team Maintenance

N. N. (Power Plant)…

N. N. (Evonik Energy Services)



Core Team OthersCore Team Others





Core Team ProductionCore Team Production







16. Energy Audit – Situation in the EU respectively Germany

16.1 Status

In the EU are a wide-spread set of directives (to be transposed into national law) targeting the energy sector. There are directives for:

• emission limits (large combustion directive) • emission trading • utilisation of water (water framework) • emission ceiling • co-generation of heat and power • use of renewables • efficiency of transport (vehicles) • efficiency of households

But there are no regulations for the efficiency of electric power generation. In the past in the EU we had discussions to implement regulations, but at the end the conclusion was that market-driven mechanism are more effective. This position was supported by the fact that the electric power generation in the EU is the most efficient worldwide. In the following one will explain why and how this impressive result has been achieved. As well as it will be shown how the efficiency is monitored. This offers the possibility to build a bridge for this experience referring the energy auditing procedure to the Indian situation. A simple key reason is: the more efficient a power plant works the most economic it is! Electric Power Market This statement is outcome of a development lasting for several decades; i.e. non- liberalised and competitive markets. For the pre-competitive area the driving force was – at the end – high cost of the domestic primary resources and/or the lack of domestic primary resources, which have to be bought from elsewhere. Consequence of this experience was a well established culture in improving the technologies needed to achieve high efficiency figures.



With the opening of the electricity market for competition this culture and state of the art of technology was an excellent basis for the challenges out of competition. The increasing concern about climate change and the necessity to improve efficiency and reduce emissions on one side and the explosion of fuel prices for fossil primary resources had enforced the pressure for further improvements. Practice Based on the given constraints - presented above - the practical use and application respectively installed technologies will be described. Philosophy The existing philosophy is determined by the competition driven constraint to be market feasible. Market feasibility means to do anything improving the competitiveness. The competitiveness is a function of

• well established customer relations in terms of prices and services, • well positioned power fleet consisting of

base, intermediate and peak load plants and of balanced fuel portfolio

• state of the art technology • skilled staff in mastering technology & market requirements as pre-requisite

In the following the major focus will be given to the technology sector respectively their solutions. Technical Solutions The efficient operation is determined by an appropriate design of the plant and its components, realised quality and the corresponding monitoring tools. The key element for pursuing the efficiency of power plant operation is the instrumentation and control system (I&C). By means of the I&C system the staff is able to follow the timely behaviour of key figures defining the efficiency as the case may be the performance.



The accuracy of the measurement devices does not reach the accuracy of the specific installations for the final approval tests, but it allows a trend analysis of selected operation plant parameters. State of the art plant process control systems are delivering the overall plant efficiency as well as the efficiency of systems and even components. Examples are the effectiveness of

• feed water pre-heating system indicators are the heat transfer factor, the terminal temperature difference and the temperature increase of each high-pressure pre-heater

• heat transfer of the boiler tubes indicators are the heat transfer factors of each bundle significantly influenced by ash deposits to be removed by the soot blowers

• air pre-heater indicators are the pressure loss and the leakage of the air pre-heater

• condenser indicator is the heat transfer factor of the condenser

Specific systems are available supporting the process control system. The goal is to facilitate the complex optimisation process with often contrary influence factors. Based on the process control system the optimisation process will be guided ensuring both optimal and safe operation (see Figure 16-1). In addition to this the minimization of outages, shortening scheduled overhauls and increasing efficiency by detailed planed outages are very important from environmental point of view.



Figure 16-1: Performance monitoring of power stations



Experience and Application IT-systems which provide the above mentioned monitoring functions are used in many German power plant units. The results of the technical and economical evaluation of the power plant are updated every 5 minutes and saved in a data historian. Thus, the trend of the performance of each unit can be monitored on any time scale. Hence plant components are evaluated online and planning data for condition based maintenance are provided. Furthermore optimum modes of operation from economic and ecological aspects are suggested, the impact of different, changing environmental conditions is evaluated and last but not least the unit's operation is optimized coming along with an efficiency enhancement. In addition to the efficient operation the role of the process control system is also the provide information concerning the life time of components and hints necessary for maintenance to be done. Figure 16-2 and Figure 16-3 give an overview the plant monitoring system is shown:

• terminal output (Figure 16-2: 151.5 MW) • unit efficiency (Figure 16-2: 42.28 %) • boiler efficiency (Figure 16-2: 94.52 %) • specific heat consumption (Figure 16-2: 2,184 kJ/kWh) • auxiliary consumption (Figure 16-2: 6.58 MW)

Losses are calculated in monetary value (here in DM)

• heating surface, economizer/reheater (Figure 16-2: 62 DM/h) • reheat spray flow (Figure 16-2: 19 DM/h) • leakage in economizer (Figure 16-2: 25 DM/h) • live steam parameter (Figure 16-2: 4 DM/h) • condenser pressure (Figure 16-2: 8 DM/h) • pre-heater (Figure 16-2: 10 DM/h) • current consumption (Figure 16-2: 0 DM/h)



Figure 16-2: Screenshot 1 of the plant monitoring system (Evonik power plant)



Figure 16-3: Screenshot 2 of the plant monitoring system (Evonik power plant)



In the following Figure 16-4 to Figure 16-12 in more detail a lignite power station is described as an example. Figure 16-4: Unit overview Figure 16-5: Combustion freeboard including burners Figure 16-6: Soot blowing system Figure 16-7: Soot blowing system and boiler reforming data Figure 16-8: Boiler scheme Figure 16-9: Operation regime of soot blowing Figure 16-10: Thermodynamic scheme Figure 16-11: Boiler air supply system, burner and overhead air Figure 16-12: Combustion Air Control Conclusions The general conclusion is that in spite of the fact that there are no legal obligations the efficiency culture is part of any power plant operation. Basis is the plant design and process control system. An indirect indicator for energy auditing are the performance indicators for availability respectively unavailability. Finally one can quote that energy auditing is essential part of an efficient electric power generation in respecting the limitations of laws of nature and coping with the challenge of a competitive market.



Figure 16-4: Unit overview



Figure 16-5: Combustion freeboard including burners



Figure 16-6: Soot blowing system



Figure 16-7: Soot blowing system and boiler reforming data



Figure 16-8: Boiler scheme



Figure 16-9: Operation regime of soot blowing



Figure 16-10: Thermodynamic scheme



Figure 16-11: Boiler air supply system, burner and overhead air



Figure 16-12: Combustion Air Control



17. Overview on Regulations, Guidelines Efficiency/Plant Performance

Best practice items for the

analysis

System part Indications Source Page Remarks

DIN 51700 Analysis of solid fuels Fuel analysis DIN 51701-2 Carrying out the analysis

Volatile elements

Hardgrove Index

Thermal efficiency

LCP-Directive, 13. BImSchV

8


13

DIN 51724-1 2 to 6 Determination of sulphur amount

Sulphur Water pollution

DIN 51724-2 2 to 5 Determination of sulphur in the fuel

Silicon Co-combustion & refuse derived fuels


13

Calcium Ash Technology for

avoiding sulphur emissions

Primary measurements for avoidance


109

Determination of the ash content

Carbon proportion

VGB M 211e Power plant coal feeding

Fuel

Coal supply Use of low-

sulphur fuels LCP-Directive, 13. BImSchV

109

Boiler Flow -through boiler / drum boiler (water processing)

VGB R 450 L 10

Steam boiler

Water / vapour circulation

Interactions VGB R 450 L 13 - 16

Guideline for feed water, boiler water and steam quality

Evaporator Combustion

chamber VGB M 224 SiC - Melting chamber

lining Superheater Intermediate

heating - heating surfaces

Accumulator




analysis


Hot components

VGB R 123 C/2.9e

Mills

VGB M 213 Coal dust measurements with the pendular zero-probe coal milling plants

Separators Temperature measurement behind separator

VGB R 200 77 GW vapour deposition and disconnection is to be allowed

VGB R 108 Fire protection in the power plant

Coal dust bunker

TRBS 2152 Assessment of the danger of explosion

Burner Deashing VGB R 201e Directive on and operation

of deashing plants VGB R 313e

Purification VGB M 221

Internal cleaning of waterpipe steam generators. Process-engineering influences on the cleaning of heating surfaces and optimisation of use

Combustion modification


97

VGB R 200 Dimensioning and operation of power plant firings

VGB TW 216 Primary measurements for the NOx reduction of dust firings for mineral coal

Reduction of excess air


140

Sorbens - injection


125 to 127

"

Sorbens - Injection for dry flue gas conduct


127 to 129

Combustion conduct

Firing

Reduced air preheating


141




analysis


Fresh air ventilator

Maximum pressure increase

KWS Training book no. 8

104

KWS Training book no. 8

104

Induced draft

Ventilator design VGB R 102 Order of ventilators for

thermal power plants Pumps Air Preheater

(air flow rate)

Heavy metals LCP-Directive, 13. BImSchV

10

Dust-avoiding techniques


98

Electrostatic filter


99

Electrostatic wet separators


101

Fabric filters (bag filters)


101

Centrifuge separator


104

Wet separator LCP-Directive, 13. BImSchV

105 to108

VGB R 103e Directive on monitoring and protection of steam turbines

Types of construction

Condensing turbine/ back-pressure turbine

Vapour purity/ conditioning

VGB R 105e The thermal behaviour of steam turbines refer to IEC Technical Specification TS 61370 (page 12)

Turbine VGB R 504e Test of big forgings and pressure pieces

VGB R 127 VGB Directive on turbine drives

VGB M 101 Rec. on how to avoid damages at steam turbo units

Turbine operation

VGB M 114 Efficiency changes at steam turbines

High-pressure part

Turbine

Low-pressure part




analysis


Fitting tappings

VGB R 107 Order and design of fittings in thermal power plants

Preheater Piping VGB R 503e Directive on internal

pipings of the turbo unit

Connecting elements

VGB R 505e Directive on screws in high-temperature areas

VGB R 450 Le Directive on the quality of feed water, boiler water and steam for copper materials

VGB R 106e Directive on condensators and other heat exchangers, part A copper alloys

VGB R 113Le Directive on condensators and other heat exchangers, stainless steel

Types of construction

VGB R 114Le Directive on condensators and other heat exchangers, Ti material

Condenser

Cleanability Condensation system

DeNOx VGB R 305 Directive on planning and ordering of installations for the reduction of NOx emissions


9

Emission of particulate matter VGB R 301 Planning and ordering of

installations for the reduction of dust emissions

Heavy metals LCP-Directive, 13. BImSchV

10

NOx emission LCP-Directive, 13. BImSchV

11

Wet scrubber LCP-Directive, 13. BImSchV

111

Types of absorbers


117

Sea water scrubber


119

Flue gas cleaning

E - filter

Magnesium wet scrubber

121




analysis


Ammonia wet scrubber

121

Spray dry scrubber

121 to 124

Volumetric flow measurements

VGB R 123 Collection of recommendations on the control technology

Pressure measurements

Temperature measurements

VGB R 170 BO-B6e

Design standards for instrumentation and control equipment

Control technology

VGB R170 A1e Measures for the avoidance and control of control technology failures

Technical unit protection

VGB R 117 Technical unit protection for thermal power plants

Electrical and control technology

Auxiliary power

VGB R161 Auxiliary power and protection of auxiliary power in power plants

Material for pressure-carrying devices

VGB R 109 d+e

Availability VGB Rv 808 Availability of thermal power plants

DIN - EN 12952 - 15

Determination of radiation losses

DIN - EN 12952 - 11

General losses

Losses

VGB R 123C Losses in start-up and shut-down processes

TRBS 2152, TRBS 2152-1, TRBS 2152-2

Assessment of the danger of explosion

General

Dangers

TRBS 2141, TRBS 2141-1

Assessment of the danger of steam and pressure



18. Example: Computerized Plant and Energy Management Systems at the Evonik Steag Voerde Power Plant

Evonik Steag Voerde Power Plant has total installed capacity of 2,120 MW. Hard coal is used as fuel. The total power generation is about 10 billion kWh/a The plant has adopted the latest computerized management systems for effective operation & maintenance of the power plants and improving the performance of the unit. The following computerized systems have been adopted

• Energy Management system • Plant management system.

Energy Management System The energy management system evaluates the existing on line measured data and recognizes the potential for optimization by assessing the processes and components. The system continuously assesses the plant operation, comparing it with the current calculated optimum, so that the unit can be run at maximum efficiency. The energy management system estimates the potential for optimization and even minimal reduction in operating efficiency is identified and pinpointed.



The energy management system is based on a three-tiered concept – evaluation, Optimization and forecast for cost relevant power plant sections. All results are evaluated at cost so that the effects of different operating parameters on cost can be directly compared.

• Computation of ratios and key figures such as efficiencies, electric energy from cogeneration, start up cost etc.

• Component evaluation (steam generator, steam water cycle, condenser, pumps, flue gas circuit etc)

• Optimizing (soot blowing, gas turbine compressor washing etc) • Fore cast (unit efficiency, maximum unit output etc)

Plant Management System Integrated plant management system, makes all operating processes rational and transparent right from shift planning to component use. The plant management system helps the plant team to detect weak spots early and optimize operating procedures. In addition it gives up to date information with all organizational, technical & commercial details. Based on master data and timely operating data acquisition, the plant management system supports the plant team in the following areas of operation:

• Minimizing of the administrative effort invested in plant management • Efficient job scheduling and control along with performance recording and

documentation • Cost optimized shift planning with integral payroll data acquisition • Optimizing and reporting of the use of operating supplies and the stocks of

supplies • Daily cost status, availability data and official requirements compliance

information • Assurance of compliance with processing and quality standards • Subject related control of information flow and authorizations • Dependable safety disconnection process with conflict check and switch in

warning



19. Latest (state of the art) technologies and status

19.1 Technology Perspectives – Availability vs. State of the Art

The technical development is a permanent process and the key attitude is the requirement for patience and perseverance in order to accept the un-evitable errors, to sustain the motivation for searching in new solutions and convince the financing instances to spend money. With these general remarks in mind one can quote that there is always a gap between state of the art and the commercial available technology. One characteristic feature of a commercial available technology is the market viability, i.e. several suppliers offer a technology at competitive conditions. The aspects of local affects for the technologies are of minor relevance in a global world. As a conclusion it is to state clear that the 600°C technology is fully commercial available. There are several suppliers of the raw materials – forging, casting, etc., as well as there are several manufactures able to master the specific requirements of the austenitic materials. At the end there is enough experience driven by some front-runners in order to know what kind of difficulties can occur or preventive measures are reasonable. Parallel to the placing orders, erecting of plants and commissioning of new plants an intensive consolidation programme is launched. It's key purpose is to broaden the range of materials, to gain better understanding of the design specifics and to open the horizon for new ideas. 19.2 Atmospheric Fluidized Bed Firing System

The fluidized bed firing is a firing that takes place in a fluidized bed made up of sand, fuel reduced to small particles (fuel portion of about 2 %) and hot combustion air (primary air through the nozzle bottom). The fuel is kept hovering above the nozzle bed and fluidizes. The small fuel particles have a large surface enabling a thorough burnout. The strong eddying flow results in a most favorable impulse and heat exchange so that a constant temperature is kept up in the fluidized bed. The combustion temperature is determined by the fuel mass flow supplied.



The temperature is adjusted such that the generation of detrimental gases (CO, NOx) is as low as possible. With fluidized bed firing it is possible to keep the nitrogen oxide emissions low as it allows to operate at a relatively low combustion temperature without temperature peaks. We distinguish between the stationary and the circulating fluidized bed:

• In case of a stationary fluidized bed the ash discharged from the combustion chamber is removed.

• The circulating fluidized bed is designed with a cyclone downstream of the combustion chamber which serves to return the discharged sand with a certain portion of ash and unburned fuel back into the combustion chamber.

For fluidized bed firing in coal-fired power plants the coal is charged with lime to bind the sulphur contained in the coal. With today's state of technology a power enhancement to 1,000 MWth is feasible with circulating fluidized bed plants and this is currently being implemented in Poland. The principal field of application for atmospheric fluidized bed plants is considered to be the combined production of electric current and heat – i.e. combined heating and power plants. The limitation of the power capacity is of rather low importance here. In addition, this design permits to utilize a broad scope of fuels ranging from coal via biomass through to residual materials. 19.3 Pressurized Fluidized Bed Firing System

Similar to the development of the gas and steam turbine plants (combined cycle turbine facilities) fuelled with natural gas, in the 1950's there was a desire to implement also for power plants fuelled with hard coal such cogeneration power plants consisting of a gas turbine process and a steam turbine process to reach maximum plant efficiency levels. The first large-scale plants with a pressurized fluidized bed firing system were then commissioned in the 1980's. For these systems, the conventional combustion chamber of



a gas turbine plant was replaced by a combustion chamber fuelled with coal. As the combustion chamber needs to be operated under increased pressure (approximately 12 bar – 16 bar) to obtain a large efficiency, it became necessary to accommodate it in a cylindrical or spherical pressure vessel (diameter approx. 22 m for a projected 300 MW plant). Based on the pressurized fluidized bed firing system, various testing facilities and pilot plants were erected:

• Testing power plant Grimethorpe, Great Britain • Pilot power plant TIDD Ohio, USA • Pilot power plant Värtan, Stockholm, Sweden • Pilot power plant Escatron, Spain • Combined heating and power plant Stadtwerke (public utility company of)

Cottbus, Germany Efficiency The operating experience gained up to date has shown that the pressurized fluidized bed firing has a limited efficiency potential. Owing to the combustion chamber temperature being limited in the fluidized bed to 850 – 900°C, the upper process temperature deter-mining the efficiency is restricted such that maximum plant efficiency values of a mere 45 % can be expected. In practical operation, it was possible to reach an efficiency of about 42 %. Apart from the limited efficiency potential, the experience gained in practical operation has particularly lead to the fact that pressurized fluidized bed firing became less important in modern power plant technology world-wide. Coal supply In a pressurized steam generator the fuel needs to be fed in either via a lockage system or in the form of a coal/water suspension. Drawbacks:

• Considerable wear at the lock fittings has continually entailed system malfunctions.

• To feed the coal without difficulty it had to be dried to a water content of



< 2 % involving a high energetic expenditure. • To prevent explosions in the lock chambers, the locking process had to be

laboriously carried out under an inert gas atmosphere. • When supplied as a coal/water suspension the slurry pumps used for the

process had an inadequate service life. De-ashing system The ash produced in the coal firing process needs to be discharged from a pressurised pressure vessel via a lockage system. Drawbacks:

• Considerable wear in the pneumatically operated conveying lines • Frequent failures of the lock fittings at an ash temperature of 850 °C

Steam generator To provide a combined process, the steam generator is accommodated in a pressure vessel. Drawbacks:

• Poor accessibility for maintenance work • Restricted possibility to timely detect malfunctions in the steam generator

area. Purification of the flue gas and gas turbine The flue gases are first cleaned by passing through a cyclone cascade and subsequently further cleaned by means of a ceramic hot gas filter, before they are fed into the gas turbine. Drawbacks:

• Fractures of the ceramic filter cartridges resulted in frequent plant standstills.

• High residual dust content led to a destruction of the gas turbine blading. • Exhaust gases from the gas turbine require another purification downstream

of the gas turbine in order to observe the currently applicable dust emission



levels. 19.4 Gasification of Coal (IGCC)

Another power plant process for the use of coal in combined gas and steam turbine processes is provided by the gasification of coal and the subsequent combustion of the produced synthetic coal gas in a downstream gas and steam turbine plant (IGCC proc-ess or Integrated Gasification Combined Cycle). In the gasifier proper, which is operated at a high gasside pressure of 40 bar, the coal is mostly converted with pure oxygen to become a synthesis gas predominantly consisting of hydrogen and carbon monoxide. The carbon monoxide portion is converted into carbon dioxide and additional hydrogen by adding water steam in a so-called shift reaction. The hydrogen can then be used for power generation in the gas turbine plant of the combined power plant downstream of the coal gasification. In this process the hot flue gases of the gas turbine are fed into the integrated water/steam circulation via a heat-recovery steam generator. Compared to other power plant designs the IGCC technology has the advantage that the carbon dioxide present in the synthesis gas can favorably be precipitated from the process at relatively high pressure, for instance by a Rectisol flue-gas purification process. In the long run, after developing underground storage deposits, this could lead to an implementation of a CO2-poor power plant technology on a coal basis. Furthermore, it is possible to produce synthetic fuels and chemicals from the synthesis gas, which provides new attractive application options for this process in the long term. Since the 1980s, several pilot plants with entrained-phase gasification and fluidized bed gasification have been operated for testing purposes. Today, various processes are offered by Shell, UHDE, General Electric and Siemens. The following pilot plants have since been erected for power generation:



• Pilot plant Cool Water, USA, operation 1984 – 1998 • Pilot plant Buggenum, NL, currently operating • Pilot plant Puertollanno, SP, currently operating

Although the IGCC technology has a high development potential, an economically reasonable application in large-scale plants could not be realised to date. The service experiences available today show that there is a continued need for development in the fields of the gas turbine, the hot-gas purification as well as the coal supply and the slag discharge. If ultimately a reliable plant operation with a high availability and a high efficiency is to be implemented, it will be necessary to further optimise the plant components currently being developed and to have them tested in pilot plants. In Germany a first pilot plant is envisaged to be commissioned in 2014. After several years of testing operation a reliable commercial plant engineering will then possibly be available around the year 2020. 19.5 Turbulent Pulverised-Coal Burner

In above comparison of the pulverised coal firing with other firing types and coal conversion methods, it has been demonstrated that none of the techniques that are comparable to pulverised coal firing is able to exceed a thermal power of 1,000 MW. Accordingly, the thermal power required ranging far above 2,000 MW can be generated only when using a pulverised coal firing process. Pulverised coal preparation In the power generation industry, fan mills have become widely accepted for the preparation of brown coal and bowl mills have established themselves for the preparation of hard coal. Essentially, the required preparation comprises the crushing (surface-area amplification), drying and screening. The screen sorting of pulverised coal formerly performed with static separators is increasingly since the 1990's being effected using speed-controlled dynamic separators as shown in Figure 19-1.



Figure 19-1: Bowl mill with dynamic separator

Burner description In an almost 100-year development of the pulverized coal burners the so-called jet and swirl stage burners (DS burners) have established themselves; they differ only marginally in terms of burnout and emissions. The swirl stage burners intended of the power plant are arranged at two opposing combustion chamber walls (in a height-offset arrangement, 3 or 2 levels). Each burner consists of a core air tube surrounded by several concentric tubes (refer to Figure 19-2). accommodated in the core air tube there is the ignition and supporting burner (designed as an oil firing), which – only for start-up and supporting load operation is driven forward to the operating position near the combustion chamber wall; usually the ignition and sup-porting burner is kept in a retracted position in order to have it as little as possible exposed to the heat radiated in the combustion chamber so that the core air tube will re-quire relatively few cooling air.

Figure 19-2: Pulverised coal burner (with out ignition and supporting burner)



The first concentric annular space surrounding the core air tube serves for conveying the pulverized coal / air mixture and is also designated as primary air. For a stable, complete and environmentally friendly combustion, the pulverized coal is to flow into the combustion chamber most uniformly distributed across the burner ring cross section. This is supported by a symmetrical line arrangement, a sufficient primary air velocity and a ring gear at the outer pulverized-coal ring main. The ring gear serves not only to stabilize the flame but also to disintegrate the chunks of pulverized coal. To have all chunks get reached and contacted by the ring gear, the annular flow of pulverized coal around the ring gear is given a slight angular momentum by swirling blades.



The burner ring cross sections serve for a staged allocation of the combustion air and they can provide their through-flowing air not only with a variable impulse (velocity and volume) but also with different swirl stages. The different swirl stages can be generated by adjustable and fixed swirl blades and supplement the required flame stability, if the stability produced by the ring gear is not sufficient. The flame stability is essentially determined by the portion of volatiles in the coal and the comminution, the fine grain portion of the pulverised coal. The portion of unburned carbon in the electrostatic precipitator ash is required to range below 5%, so that the ash can be further utilised in the cement industry. This is primarily reached by a low coarse grain portion in the pulverised coal, which in turn results from the high grinding performance and a strict grain-size screening in the separator. Turbulent burner aspects: With the NOx primary measures (see BAT measures) harmonised accordingly, it is possible for today's use of "steamcoal" from South Africa or Colombia to reach nitrogen oxide concentrations ranging between 400 mg/Nm³ and 500 mg/Nm³ in the flue gas at the discharge end of the radiation chamber (in front of the bulkhead). Here, the excess air may fluctuate around the Lambda value 1.15 and the unburned matter in the electrostatic precipitator ash can be kept well below 5 % when run at the "optimum operation point". We have explained and commented on the NOx primary measures relating to the BAT measures demonstrating that these requirements are fulfilled for the swirl stage burners. Consequently, today's best available technology is the pulverized coal technology. 19.6 Supercritical Technology

Supercritical (SC) and ultra-supercritical (USC) power plants operate at higher temperatures and greater steam pressures than conventional systems. They require less coal per megawatt-hour, leading to lower emissions per megawatt (including carbon dioxide and mercury), and lower fuel costs per megawatt, leading to higher efficiency and lower fuel costs.



19.7 Six Sigma Concept

Six Sigma is a powerful data driven, customer focused management methodology that delivers validated improvements in profitability and productivity. Six Sigma implementation will guide organization to:

• improve Customer Satisfaction • Increase Profitability • Increase Productivity

In most companies today, the cost of poor quality represents 20 % to 30 % of total revenues. The Six Sigma approach implements the proven methodologies for minimizing these costs while reaching world-class quality levels by focusing on breakthrough performance (improvements of 50% or more). For more details on technological perspectives, please refer the following Annexures XIII to XX.

Annexure XIII IGCC technology

Annexure XIV Supercritical and ultra super critical technology

Annexure XV CFBC technology

Annexure XVI Six sigma process

Annexure XVII PFBC technology Annexure XVIII Advanced Technologies of Preventive Maintenance for Thermal Power

Plants-write up by Hitachi

Annexure XIX Oxyfuel technology for fossil fuel-fired power plants – Dresden University of Technology, Germany

Annexure XX Results of oxy-fuel combustion for power plants- Dresden University of Technology, Germany



20. Operating Efficiency of EU Power Plants and Efforts initiated for Improvement

The efficiency of both electricity, and combined electricity and heat production from conventional thermal power plants improved steadily between 1990 and 2004. This was due to the closure of old inefficient plants, improvements in existing technologies and the installation of new, more efficient technologies, often combined with a switch from coal power plants to more efficient combined cycle gas-turbines. This trend is expected to continue in the future. However, the rapid growth in fossil-fuel based electricity production outweighs some of the environmental benefits of the efficiency improvements. 20.1 Rationale

The majority of thermal generation is produced using fossil fuels with associated environmental impacts such as greenhouse gas emissions, but can also include biomass, wastes and geothermal. Whilst the level of environmental impact depends upon factors such as the particular type of fuel and the extent to which abatement technologies are used, all else being equal, the greater the efficiency the lower the environmental impact for each unit of electricity produced. Annexure XXI shows the actual efficiency of thermal power plants in Europe, efficiency improvement over a period of time (paper published by European Environmental Agency) and corrective actions taken for improvement.



21. Best Practices Applicable to Indian Scenario

The following best practices which can be applicable are discussed in this section:

• Online monitoring system • Statistical process control for fault detection • Maintenance management system • Pooling of inventories • Benchmarking of component efficiencies • Training including simulator training

21.1 Online monitoring System

This system is now gaining wide popularity and being used for all new power plants and also being introduced during retrofit of existing systems. The details of this system is given in annexure XXII. 21.2 Statistical Process Control Process Detection

Statistical Process Control (SPC) is an effective method of monitoring a process through the use of control charts. Control charts enable the use of objective criteria for distinguishing background variation from events of significance based on statistical techniques. Much of its power lies in the ability to monitor both process centre and its variation about that centre. The details are described in annexure XXIII. 21.3 Simulator Training on Power Plant Operation

Simulator training is the best option now available to power plants, which gives the feeling of operating a real Power Plant without incurring any generation loss or damaging any plant equipments. Simulator includes advanced training tools and features, which are as important as the



simulator itself in successfully achieving training goals. By integrating these tools into the simulators, which delivers not only training simulators but comprehensive training "systems". As a result, operator training becomes significantly more productive, and the need for intensive instructor involvement is minimized. The detailed write up on the simulator is given in annexure XXIV. 21.4 Maintenance Management Systems

The Maintenance Management Systems is a part of Integral Plant Management aided by sophisticated software. These systems are very popular in Europe and have significant potential of applications in developing countries. The details of such system are given in annexure XXV. 21.5 Benchmarking Practices

The benchmarking practices are described in chapter 15.



22. Miscellaneous

The report provides the brief write up on the following

• Monitoring and controlling of power plants (refer to annexure XXVI) • Maintenance practices (refer to annexure XXVII) • Sizing criteria of thermal power plants (refer to annexure XXVIII) • Stores inventory and procurement systems (refer to annexure XXIX) • Key operating parameters of power station (refer to chapter 11)

fantastic power plant audit

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