minimal load reduction(mlr) and storage systems ......minimal load reduction and...
TRANSCRIPT
Minimal Load Reduction (MLR) and
Storage Systems as Flexibilisation
Options for coalfired Steam Power-
Plants »
Dr. Thomas Hofbauer
EnBW Energie Baden-Württemberg AG
National Seminar on
“Flexibilization of Thermal Power Plants — Learning
from German Experiences”
01st December 2017, Gulmohar Hall, New Delhi, India
1. EnBW Power Generation at a Glance
› EnBW Power Generation Portfolio
› EnBW Power Generation Engineering Services
› EnBW Conventional Power Plant Fleet
2. Minimal Load Reduction
› Background
› Fuel Supply and Heat Generation Systems
› Flue Gas Cleaning and Filtering Systems
› Water-Steam-Cycle and Steam Turbine
› Summary Minimal Load
3. Outlook : Thermal and Electrical Storage Systems
› Flexibilization of Power Plants by Thermal Energy Storages
› Electrical Storage for Flexibilization of Power Generating Plants
2Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Agenda
1st Chapter
3
EnBW Power Generation at a Glance› EnBW Power Generation Portfolio
› EnBW Power Generation Engineering Services
› EnBW Conventional Power Plant Fleet
EnBW Power Generation at a Glance
4
EnBW Power Generation Portfolio
› Thermal Power Stations / CHP (Coal, Gas, Oil, Biomass, Waste)
› Nuclear Power Plants
› Renewable Energies, i.e. Wind onshore & offshore, Water power, Geothermal Energy
› District Heating, Industrial Power Supply
EnBW Power Generation Engineering Services
› Vast experience in engineering, construction, operation and maintenance of power stations
› High professionality and customer orientation
› Tailor-made and individual concepts and solutions
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
EnBW Power Generation at a Glance
5
Heilbronn Unit 7
Power Rating 812 MW
Commissioning 1985
Boiler OEM EVT / Sulzer
Feed Steam Params 197 bar, 540°C
Minimal Load 28%
Altbach HKW2
Power Rating (solo/GTE) 335 / 428 MW
Commissioning 1997
Boiler OEM Steinmüller
Feed Steam Params 249 bar, 540°C
Minimal Load 31%
Altbach HKW1
Power Rating 476 MW
Commissioning 1985
Boiler OEM Steinmüller
Feed Steam Params 195 bar, 540°C
Minimal Load 30%
Karlsruhe RDK 7
Power Rating 536 MW
Commissioning 1985
Boiler OEM Steinmüller
Feed Steam Params 181 bar, 535°C
Minimal Load 33%
Karlsruhe RDK 8
Power Rating 536 MW
Commissioning 2016
Boiler OEM Steinmüller
Feed Steam Params 285 bar, 603°C
Minimal Load 35%
Conventional PP Fleet
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
2nd Chapter
6
› Background
› Fuel Supply and Heat Generation Systems
› Flue Gas Cleaning and Filtering Systems
› Water-Steam-Cycle and Steam Turbine
› Combined Heat and Power
› Summary
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
The Economic Case for Mimimal Load Reduction
› Market price often oscillates around marginal cost level
› Revenue/Loss = ( market price [€/MWh] - marginal costs [€/MWh] ) * P [MW] * Time [h]
› Low ML is economic benefit!
Minimal Load Reduction Background
7
Picture of tangential
combustion in single-
mill operation from the
bottom of the boiler
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Minimal Load Reduction Background
8
Historical Development of Minimal Load
› Before 2000: 2-Mills-Operation− ML 30-40% with coal fire only; ML 25% with coal fire with supporting oil fire
− availability had been a high priority: Minimum load : 2-mill-operation, no plant trip
› 2000-2010: 2-Mills-Operation− ML 25%: with coal fire only (no supporting oil fire), forced circulation
› 2010 – now:− EnBW´s MLR project goal : Minimal Load of 15-20% with coal fire only
− Further reduction of ML only possible with 1-mill operation because of flame stability
› Higher ML for lignite-fired steam power plants
% LOAD 0 5
1 MILL
3 MILLS
4 MILLS
30 6040 85
2 MILLS
100 10510 15 20 25 9565 70 75 8035 9045 50 55
future ML
past ML
critical flame stability
regular operating range
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Fuel Supply and Heat Generation Systems
9
BURNER LEVEL 10
BURNER LEVEL 20
BURNER LEVEL 30
BURNER LEVEL 40
Coal Feeders, Mills and Firing
› Stable range for coal feeders: 60%…85%
› One mills for each of the 4 burner levels, tangential firing system
upper air and oil burner
pulverized coal jet-burner
middle air
pulverized coal jet-burner
lower air and oil burner
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Flame Stability
› Low load in 2-mill operation, the mill and coal feeder load would be decreased to approx. 40..50 percent or below which result in poor flame stability
› For a comparable PP load in 1-mill operation, the coal feeder and mill load could be ≥80 percent with a stable flame
› Coal feeder/mill load preferable at 60…85 percent
10
Fuel Supply and Heat Generation Systems
Picture of tangential
combustion in single-
mill operation from the
bottom of the boiler
Flame quality for burner
levels 30 and 40 in top and
middle diagram; coal feeder
load in bottom diagram for
test 5 and test 6 (1-mill ops)
and test 7 (2 mills ops)
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Fuel Supply and Heat Generation Systems
11
LEVEL 10
LEVEL 20
LEVEL 30
LEVEL 40
Burner Levels and Excess Air
› minimum load (1-mill operation) preferably with firing of level 30 or 40(� also positive effect on flame stability)
› Combustion while minimum loadpreferably with high excess air (λ total ~ 2)
Heat Transfer and Feed Steam / RH Steam
› Heat transfer from flue gas to water-steam-cycle is at higher levels, thus lessheat input to the evaporation; more heatinput to the superheating
› Feed steam und RH steam temperaturesremain at high levels (approx. 20K lowercompared to full load)
› Sliding pressure curve not to apply at verylow part load
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Temperature in Flue Gas Duct Channel
› No essential temperature drops compared to previous minimal load (30-40% load case)
SCR-DeNOx
› Temperature before DeNOX were sufficiently high in all but one case. This has been corrected with a ratio change of secondary air
› Precise control of NH3-injection is challenging
12
Flue Gas Cleaning and Filtering Systems
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Water-Steam-Cycle and Steam Turbine
13
HP Turbine (HPT) Ventilation
› HP turbine tends to ventilatewhen mass flow (identical tolow pressure drop accross HPT)
› Keeping RH pressure throughIPT valves make situationworse.
› HPT exhaust temperature maydrastically increase withinseconds �hazzard of turbinetrip or damage
› steam extraction, e.g. fordistrict heating, increases thetendency towards ventilation
HPT exhaust15 bar, 380°C
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Water-Steam-Cycle and Steam Turbine
14
RH Massflow
› Ensure minimal RH massflow (steam extraction from cold RH may be critical)
› Low RH massflow can result in damage of RH heat exchanger piping.
IP / LP Turbine Ventilation and Condenser
› LP turbine tends to ventilate when mass flow / pressure gradient is low
› Water injection off to prevent erosion
› Ensure low condensor back-pressure (last stage vibration excitation)
› Droplet erosion not an issue (wet steam regio unchanged, lower flow velocities)
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Boiler Feedwater Pump and Circulation Pump
15
Boiler Feedwater Pump and Steam Use
› Superheated Steam for BFP
› Also applies for CHP-PP
› Lower Pressure / higher volumetric expansion: steam from extractions: check the smallest Diameters (“vena contracta”)
Boiler Circulation Pump
› The 1-mill-operation requires to operate the boiler circulation pump (forced circulation). The pump control is automated
› the load regime for which the circulation pump is operated at low part load should be avoided
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Water-Steam-Cycle and Steam Turbine
16
Combined Heat and Power (CHP)
› Heilbronn Unit 7 : steam extraction for district heating / process steam from cold reheat
› Karlsruhe RDK 7 : steam extraction for district heating from hot reheat �higher cogeneration ratio
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Summary MLR Project
17
MLR Project Management
› Thorough planning prior to field experiments essential
› Close cooperation with plant operators and turbine OEM has been beneficial
› Power plant has to examined as a whole
› Individual technical/physical limitations for each power plant
› Minimal Load Reductions as specified in the project objectives have been achieved
Achievements
Altbach HKW 1 Heilbronn Unit 7 Karlsruhe RDK 7
Power Rating, elec. 476 MW 812 MW 536 MW
Minimum load, previously1) 28% 30% 33%
Minimum load, achieved 14-18% approx. 15% 15-18%
Co-Generation / CHP max. 80...100 MW th 15 MW th2)
55 MW th3)
70…80 MW th
1) ETG 20122) 1-mill operation3) 2-mills operation
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
3rd Chapter
18
Thermal and Electrical Storage Systems (Outlook)
› Flexibilization of Power Plants by Thermal Energy Storages
› Electrical Storage for Flexibilization of Power Generating Plants
“KRAFTWERKSFLEXIBILISIERUNG DURCH THERMISCHE ENERGIESPEICHER” (“FLEXITES”)
› Flexibilization of Power Plants by Thermal Energy Storages
› Integration into thermal coal-fired power plants
› 2017-2020
Thermal and Electrical Storage Systems (Outlook)
19
LP PH
LP PH LP PH
Deaerator
Boiler
HP PH HP PH
Thermal EnergyStorage System
Minimal Load Reduction and Flexibilization Options for coal-fired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Sample concept of thermal storage to increase operational flexibility as
PP integrated system (courtesy of Siemens AG)
HPT IPTLPT
COND
BFP
Thermal and Electrical Storage Systems (Outlook)
20
“KRAFTWERKSBATTERIE HEILBRONN”
› Joint venture between Bosch AG and EnBW AG (*2017)
› Electrical energy storage for flexibilization of power
generating plants / primary/secondary control energy
› First storage system (20 MWh, 20 MW) at the
Heilbronn Unit 7 power plant
- erection started in November 2017
- commissioning spring 2018
Electrical Storage System during erection phase of the Electrical Storage
Plant (Nov. 2017)
A Joint Venture of
Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG
Contact
21
EnBW Energie Baden-Württemberg AG
Dr. Thomas Hofbauer
Schelmenwasen 15
70567 Stuttgart
Germany
℡ +49 (0) 711 289-89155
� www.enbw.com