Minimal Load Reduction (MLR) and Storage Systems as Flexibilisation - - PowerPoint PPT Presentation

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Minimal Load Reduction (MLR) and Storage Systems as Flexibilisation - - PowerPoint PPT Presentation

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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-Wrttemberg AG National Seminar on Flexibilization of Thermal Power Plants

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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 Experiences” 01st December 2017, Gulmohar Hall, New Delhi, India

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  • 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

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Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG

Agenda

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1st Chapter

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EnBW Power Generation at a Glance

› EnBW Power Generation Portfolio › EnBW Power Generation Engineering Services › EnBW Conventional Power Plant Fleet

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EnBW Power Generation at a Glance

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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,

  • peration 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

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EnBW Power Generation at a Glance

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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

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2nd Chapter

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› 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

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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

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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

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Minimal Load Reduction Background

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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 5 1 MILL 3 MILLS 4 MILLS 30 60 40 85 2 MILLS 100 105 10 15 20 25 95 65 70 75 80 35 90 45 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

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Fuel Supply and Heat Generation Systems

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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

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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

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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

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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 load preferably 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 less heat input to the evaporation; more heat input to the superheating › Feed steam und RH steam temperatures remain at high levels (approx. 20K lower compared to full load) › Sliding pressure curve not to apply at very low part load

Minimal Load Reduction and Flexibilization Options for coalfired Steam Power-Plants · 12/1/2017 · Dr. Thomas Hofbauer, EnBW Energie Baden-Württemberg AG

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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

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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

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Water-Steam-Cycle and Steam Turbine

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HP Turbine (HPT) Ventilation › HP turbine tends to ventilate when mass flow (identical to low pressure drop accross HPT) › Keeping RH pressure through IPT valves make situation worse. › HPT exhaust temperature may drastically increase within seconds hazzard of turbine trip or damage › steam extraction, e.g. for district heating, increases the tendency towards ventilation

HPT exhaust 15 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

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Water-Steam-Cycle and Steam Turbine

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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

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Boiler Feedwater Pump and Circulation Pump

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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

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Water-Steam-Cycle and Steam Turbine

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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

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Summary MLR Project

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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 2012 2) 1-mill operation 3) 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

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3rd Chapter

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Thermal and Electrical Storage Systems (Outlook) › Flexibilization of Power Plants by Thermal Energy Storages › Electrical Storage for Flexibilization of Power Generating Plants

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“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)

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LP PH LP PH LP PH

Deaerator Boiler

HP PH HP PH

Thermal Energy Storage 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 IPT LPT COND BFP

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Thermal and Electrical Storage Systems (Outlook)

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“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

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Contact

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EnBW Energie Baden-Württemberg AG

  • Dr. Thomas Hofbauer

Schelmenwasen 15 70567 Stuttgart Germany

  • t.hofbauer@enbw.com

℡ +49 (0) 711 289-89155

  • www.enbw.com