seshasayee paper and boards ltd. national workshop...

High Efficient Cogeneration in Seshasayee Paper -Erode

Dr T.G.Sundara Raman

Seshasayee Paper and Boards Ltd.

National Workshop for

Promoting Industrial Energy Efficiency

KEP/BEE New Delhi

8th Nov. 2016

WHAT IS

COGENERATION

Grid Power Generation Station Power Consumption

T&D Losses

Net Power from TPS

Net Power Avail at Plant

Net Power for Process Req.

Power Generation in HP Cogen

APC @ Cogen

HP Steam Generation Co-Gen

Plant

ASC Net Steam to Process

Power Borrowed from Grid to Cogen Process

CHP needs +Surplus Power for Export

Power for

Export

SPECIFICATIONS OF THE 2 HP COGEN UNITS

CPP Chemical Recovery Cogen

Boiler #10 Parameter Boiler #11

AFBC Boiler Type Chemical Recovery Boiler

117 TPH

ECR : 106 TPH

Rated Steam

Evaporation

95TPH(Phase1*)

140TPH(Phase2)

106 kg/cm² SOP 65 kg/cm²

510˚C SOT 465˚C

135˚C Feed inlet temperature 135˚C

Imported coal

Fuel

Black liquor

@ 70% solids concn.

21 MW- DEC STG 16 MW- EBP

10.5/4.0 kg/cm² E1/E2 10.5/4.5 kg/cm²

0.09 ata Condensing --

20.4 MW Capacity 11 MW(Phase1*) /

16 MW(Phase2)

5

E2

E1 E1

E2

BLR#10 VHP BLR#11

HP

P2 P1

21 MW

DEC

16 MW

EBP

LP LP

MP

STEAM & POWER OPTIMISATION WITH

2 HP COGEN BATTERY ON LINE

Atmospheric Fluidised Bed Combustion High Pressure Boiler [#10]

[Babcock UK] -Original Design

• Bubbling Fluidised Bed Combustion Boiler with economizer & air-heater at back-end

• High pressure (106 ksc) unit

• 510ºC Steam Temperature

• No in-bed Superheater

• Rifle bore Studded Bed Coils

• Under-Bed Feeding

• 135ºC Feed water Temperature

• Enviro-Coal (Low S & Ash content)

• High Thermal Efficiency ( > 80 % )

Rifle bore bed

coil tube

INNOVATIVE PROJECT - 1

Conversion of Bubbling to Spouted AFBC HP Boiler with increased bed heating

surface for enhanced High Pressure Steam & Power generation

Date of Commencement : 05.03.15 Date of Completion : 26.04.15

Investment : Rs 10 Crores Monetary savings : Rs 11.94 Crores

Increasing bed coil heating surface accommodated within the existing

furnace area, thereby increasing steam generation in HP Boiler

8

BEFORE RETROFIT – SINGLE

HEADER SINGLE BED COIL

DESIGN

DECK PLATE / BOTTOM

WATER WALL DECK PLATE

AFTER RETROFIT – DOUBLE

HEADER DOUBLE BED COIL

DESIGN

Imported Coal

A.Proximate Analysis

Constituent Unit As Fired

Moisture % 20

Ash % 4.3

Volatile Matter % 35-36

Fixed Carbon % 40-41

GCV kcal/kg 5410

B. Elemental Analysis

Carbon

:

48.7 %

Hydrogen : 5.3 %

Nitrogen : 1.0 %

Sulphur : 0.5 %

Oxygen : 20.2 %

Halogens : Traces

Heavy Metals : BDL

High Combustion efficiency : >99%

Design

• LOI [Design] : ~15%

• UBC Loss : 1.1 %

____________________________________

Actual

• LOI : 9 to 10%

• UBC Loss : 0.6- 0.7%

• CO in flue gas : Traces

• Combustion effy : > 99 %

Action Initiated

• Stoppage of PA Fan

• Fuel Nozzles thoroughly cleaned during the last shut

• Bed material topped up with fresh material when required.

Steam Cost Reduction through Switch from Low to High Grade Coal

in Upgraded Boiler # 10

Parameter Units Earlier Present Remarks

Low GCV High GCV Switch to higher

grade coal

GCV ( arb) Kcal/kg 4730 5400 As received basis

TM % 27 19-20 Total Moisture

Landed Cost Rs/te 5000 4850 Imported Coal

Efficiency % 78 83 Boiler thermal η

Steam Evapn. t/t 5.4 6.6 Fuel based

Net Steam to fuel t/t 5.2 6.35 Incl transf & carpet

losses

Spec Energy Consn

redn.

% Basis 4-5% Impact on PAT

Increase in Steam generation : 80 to 105 TPH

Increase in Power generation through 21MW STG :

13.5 to 19 MW

Station Power consumption reduction : 7000 units/day

Power Export : 3 to 4 MW (Commencement from Nov 2015)

Grid Power Import drastically reduced

Additional LP Steam for Process : Ensured

12

Boiler 10 upgradation

Impact on overall Operational Results & Analysis

INNOVATIVE PROJECT - 2

Coal fired Boiler 10 - Station Power consumption reduction by

integrating Energy Efficient Boiler feed Pump with Low

Differential Pressure Control Valve.

Date of Commencement : Aug 2015 Date of Completion : Oct 2015

Investment : Rs 2 Lakhs Monetary savings : Rs 32 Lakhs

Prelude : High pressure drop across the control valve of Boiler Feed pump had

triggered the design of a control valve with lower differential Pressure so as to

retain the existing energy efficient Boiler feed pump.

Benefits achieved :

• Station power consumption reduction : 5000 KWh /day

• Net power available for export : 0.2 MW

• Annual GHGE reduction : 2000 tCO2e (2015-16)

Why it is innovative: Energy efficient Boiler Feed Pump integrated with specially

designed control valve with lower differential pressure to effect station power

consumption reduction - first of its kind in Manufacturing Industry .

Replication potential: Can be replicated by all industries for their

boiler feed pumps.

13

Advanced Energy Conservation Scheme

BFP for H.P. Steam Generator [Boiler 10]

Efficiency [%] of BFP in Operation

40

50

60

70

80

70 84 98 112 126 140

LargeBFP EFBFP

Feed Water Flow to Boiler 10 [ TPH]

BF

P E

ffic

iency [

%]

DP across EFBFP Control valves –Boiler 10

0

10

20

30

40

70 82 94 106 117

CV original CV LowDP

Feed Water Flow to Boiler 10 [ TPH]

DP

across B

FP

CV

[b

ar]

Energy Saving : 1000 units/day Energy Saving : 4500 units/day

Boiler

Steam

Rate

TPH

Efficiency

%

Power

Consumption

Power

Savings

%

Daily

Power

Savings

in Units

Standby

BFP 105 55-60 20600 Basis Basis

EE BFP + Low DP CV 105 70 15200 25 5400

Energy Efficient BFP with Low DP Control Valve to suit

Innovative Project

Power Management – Boiler Feed Pump

.

Process condensate polishing

Waste heat recovery through PHE

Condensate polishing resin bed

ACF MB

ST

FWT

Process Hot /

Condensate Tank

Filter

Polished

Condensate

To Deaerators

PHEs Hot

Fluid

Process Condensate : 90°C to 40°C

DM Water Preheating : from 32°C

Heat Recovery : 4 MWt

CPU+ HRU - INTEGRATED WATER &

ENERGY MANAGEMENT -BOILERS

Higher Cycle efficiency of STG relating to increased Power

generation

Increased Condensing loading resulting in lowered Specific

Steam Consumption

Marginal increase in Generator efficiency due to increase in

Power Generation

Maintaining rated Main steam temperature of ~ 505 °C

18

Impact on Enhanced performance of DEC STG

– Boiler #10 upgradation

CPP- Power Generation Enhancement

Increase in Gross Cycle efficiency

Successful Implementation of

Innovative schemes , had resulted in :

Net Power generation enhancement -through:

1. Minimize Exhaust steam Dryness Fraction

2. Maximize Condenser Vacuum

3. Generator efficiency enhancement

4. Minimizing/Non-operation of inefficient MP Boiler(s)

5. Reduction in Station Power Consumption through High

Energy Efficiency BFP with low DP Control Valve in place

21 MW 16 MW

Type Double Extraction cum

Condensing

Extraction cum Back

Pressure

Design 97.6 % 97.7 %

Actual 97.9 % 98.1 %

[Industry Record]

Gain 0.07 MW 0.06 MW 23

High Generator Efficiency

21 MW, 16 MW Steam Turbo-Generators

13.6

11.7

10.5

11

11.5

12

12.5

13

13.5

14

2014-15 2015-16

Cogen Station Power Consumption[%] S

PC

[%

]

INNOVATIVE PROJECT - 3

DM water switch related to heat recovery from Turbo-generator winding heat dissipation for increased Cycle efficiency

Date of Commencement : Jan 2016 Demonstration done : Aug 2016

Investment : Re 1 Lakh Monetary savings :Rs 20 Lakhs

Proposal : DM water instead of cooling tower water is supplied to generator air cooler

and is returned to the De-aerator at a higher temperature thereby reducing LP steam.

25

STEAM

TURBINE

G

COOLING TOWER

WATER IN

COOLING TOWER

WATER OUT

GENERATOR AIR COOLER

STEAM

TURBINE

DM

WATER IN

DM

WATER OUT

G

GENERATOR AIR COOLER

EXISTING MODIFIED

INNOVATIVE PROJECT - 3

BACKGROUND : Energy wasted through the cooling tower and the fouling of generator tubes triggered the scheme development.

BENEFITS ESTIMATED:

• De-aerator LP steam consumption reduction by 12 TPD

• Annual GHG emission reduction – 1100 tCO2e

• Fouling of generator air cooler tubes is avoided

• Enhanced winding temperature reduction.

REPLICATION POTENTIAL :

• Steam turbines with condensing units related to Cogeneration can take advantage of the scheme through implementation .

• Concept can be suitably modified for Thermal Power plants by utilizing turbine condensate instead of DM water.

26

RECOVERY COGEN ENERGY

DISTRIBUTION

.

Boiler

MSL

APH

EBP

Turbine P

LP Steam

for Process

PRDS

Fuel-

Input Energy

Deaerator

BFP

Evaporator

MP Steam

for Process

APH

Recausticizing

Fuel Heating

Innovation related to Low Carbon Economy

Maximizing Green Power generation in

Recovery Cogen through:

• Minimal/No extraction & maximizing Exhaust

LP flow in 16 MW STG

• Maximizing steam inlet temperature through

operating the Recovery Boiler at high SOT &

effecting reduction in steam temperature loss

through highly effective advanced state of

the art insulation of Main steam pipe-line

16 MW STG : Energy Management

Maximizing E2 steam with E1 minimal

------------------------------------------------------------

•Power gen. increase …. : 0.4 MW

•Addl. power gen. through

increase in flow of E2 ... : 0.05 MW

•Addl Green power gen. : 0.45 MW

•REC ………… : 300 units/month

•GHGE reduction : 1800 tCO2/yr

Waste to Power

Advanced Boiler Main steam

pipeline reinsulation- online

------------------------------------------------------------------------------

Replacement of existing insulation

with fresh insulation mattress of

higher thickness [210mm]& density

[140kg/m3] ; Advanced cladding pin

design

Steam temperature drop redn. from

10/12°C to 5/6 °C.

Radn & convecn heat loss redn.

Enthalpy gain in 16MW STG: 3kcal/kg

Addl. Power genern : 0.3 MW

GHGE Reduction : 2400 tCO2/ yr

Increased Feed Water inlet temperature

from 136 to 141° C to Economiser

Power gen. increase …. : 0.06 MW

Green Power enhancement:0.5 MU/yr

REC ………… : 40 units/month

•GHGE reduction : 250 t CO2e / yr

31

Recovery HP Cogen : Energy Management

Increased Feed water inlet temperature to Boiler :Case Study

Conclusions

Energy Efficiency Gains through Modified Boiler Design

• Quantum increase in HP Boiler Steam generation at rated steam temperature

• Overall Heat rate of Boiler House [CPP] efficiency enhancement with high steam economy-Steam loading reduced on inefficient MP Boilers

• Consequent increase in turbine steam loading had resulted in high cycle efficiency

• Surplus Power available for Grid Export [ ~3MW ]

• Availability of Boiler 10 with 21 MW STG : high at >98%

• GHG Emission reduction of over 35000 tCO2 /annum

Leveraging Aux. Steam Consumption Process condensate

polishing with HRU

Reduced DM water

consumption and lowered

Deaerator steam consumption

Higher feed water temperature Increase in Steam economy

High Feed water quality Low Blow-down ;

Pressure part healthiness

Combustion intake air reducting

planned

LP steam consumption lowered

LEVEREGING ELECTRICAL POWER IN HP COGEN

• Set Steam Inlet Temperature to Turbine at

Design Maximum

5 to 10 kwh/t

• Low Enthalpy Drop through economic sizing

and heavy insulation of main steam line

5 to 10 kwh/t

• High Energy Efficient Boiler Feed Pumps

integrated with Low DP Control Valves

7000 units/day

• Increase in Steam Generation with Boiler

Water Temp. at 141°C (instead of 105°C)

+30 kwh/t

• High Efficiency Turbine (With lower exhaust

steam dryness) for DEC Steam Turbine

30 to 50 kwh/t

• Identifying & Changing from MP to LP Steam

(Steam Switch) for Process needs

To Suit

Cleaner Environment Facets

Low S ( < 0.4 %)in coal SOx emission low

Low Ash ( 3 to 4 %) in coal Bottom/Fly-ash handling

minimal

High efficiency 3 field ESP Low SPM & RPM in stack gas

< 30 mg/Nm³

Imported coal with high

GCV

Particulates, SO2 & NOX

quantity discharged : Low

GHG Annual Emission

Reduction

42000 tCO2e

For further enquiry please contact:

Dr T.G.Sundara Raman

Mob. No,: 9443340731

email : drram@spbltd.com

36

Thank You