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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 Experiences01 st December 2017, Gulmohar Hall, New Delhi, India

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Page 1: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 2: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 3: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

1st Chapter

3

EnBW Power Generation at a Glance› EnBW Power Generation Portfolio

› EnBW Power Generation Engineering Services

› EnBW Conventional Power Plant Fleet

Page 4: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 5: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 6: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 7: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 8: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 9: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 10: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 11: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 12: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 13: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 14: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 15: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 16: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 17: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 18: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 19: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

“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

Page 20: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

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

Page 21: Minimal Load Reduction(MLR) and Storage Systems … · 2017-12-05 · Minimal Load Reduction(MLR) and Storage Systems asFlexibilisation Options forcoalfiredSteamPower-Plants » Dr

Contact

21

EnBW Energie Baden-Württemberg AG

Dr. Thomas Hofbauer

Schelmenwasen 15

70567 Stuttgart

Germany

[email protected]

℡ +49 (0) 711 289-89155

� www.enbw.com