Overview of development of Oxyfuel Boiler Technologies in the ENCAP project

Transcription

1 Overview of development of Oxyfuel Boiler Technologies in the ENCAP project ENCAP/CASTOR Workshop, Billund, March 16, 2006 Marie Anheden Vattenfall, Stockholm, Sweden 1

2 Oxyfuel Combustion Combustion of fuel with O 2 instead of air results in a flue gas consisting of mainly CO 2 (about 90%(v) on dry basis) and minor amounts of non-condensable gases Flue gas is recycled to control the combustion temperature Can be applied to both natural gas and coal but have different implications depending on the preferred technology for energy conversion (boiler with steam turbine vs. GTCC) The work in ENCAP SP3 is only related to Oxyfuel combustion of solid fuel such as bituminous and lignite coal and pet coke Previous experience: oxygen enriched combustion Experience from glass- and metal industry Tests in small-scale rigs (few kw up to few MW th ) 2

3 Oxyfuel combustion for coal Based on existing boiler and steam turbine technology Can take advantage of ongoing development to increase efficiency of conventional steam power plants Opportunity to reach high CO 2 capture rate and near zero emission Co-capture of other pollutants? Reduced investment in flue gas cleaning equipment? Reduced boiler heat losses and compact boiler design No bulk N 2 in flue gas gives reduced heat loss Reduced recycle rate gives reduced boiler size and cost Availability of almost pure oxygen enables enhanced combustion control 3

4 Challenges: oxyfuel technologies Increased knowledge on fundamentals of combustion behaviour and emission formation/reduction Experimental and modelling Development and adjustment of component design and layout (boiler, burner, fuel feeding system, flue gas cleaning and recirculation devises...) Optimisation of flue gas treatment and CO 2 processing to balance Environmental issues Investment cost Operational issues CO 2 product requirements (including effect on transport and storage system and risk and environmental aspects) CO 2 recovery Energy efficient integration and optimisation of the process Recovery of low temperature heat in flue gas and CO 2 compression train Reduced energy consumption for air separation 4

5 ENCAP SP 3 Oxyfuel Boiler Technologies 600 MWe (gross) Bituminous coal oxyfuel PF plant 1000 MWe German lignite oxyfuel PF plant 380 MWe Greek lignite oxyfuel PF plant Fuel 450 MWe Bituminous coal oxyfuel CFB plant 5

6 ENCAP Oxyfuel Boiler- Participating Organizations Vattenfall AB, Sweden University of Stuttgart, Germany Energi E2 AS, Denmark Chalmers University of Technology, Sweden Mitsui Babcock Energy Limited, UK Siemens Aktiengesellschaft, Germany L Air Liquide, France ALSTOM Power Centrales Steam Power Plant, France ALSTOM Power Boilers SA, France ALSTOM Power Boiler GmbH, Germany RWE Power AG, Germany Public Power Corporation S.A., Greece University of Ulster, United Kingdom 6

7 SP3 Goal and objectives Goal To show that oxyfuel combustion of bituminous coal, lignite can reach a CO 2 avoidance cost of 20 per ton of CO 2 by applying innovative design and utilise process integration opportunities Objectives to develop and validate oxyfuel combustion based power plants concepts for bituminous coal and lignite for a greenfield plant To provide a conceptual boiler design and suggest its integration with a power generating plant to provide an economically competitive technology To examine special issues related to oxyfuel combustion in laboratory and pilot scale to be able to accommodate for those in the plant design and mitigate risk 7

8 Work packages WP 3.1 Fundamentals in Oxyfuel Combustion Combustion tests and in laboratory scale test rigs ( kw). (Test facilities) Deposits, material and flue gas treatment aspects WP 3.3 Oxyfuel greenfield coal PF definition Conceptual design of greenfield oxyfuel PF plant based on advanced supercritical power plant technology Integration and optimisation in combination with economic evaluation Operational characteristics, risk analysis Both bituminous coal and lignite (PF concept) WP 3.4 Oxyfuel greenfield coal CFB definition Conceptual design of greenfield oxyfuel CFB plant for coal (and pet coke) (CFB concept) Integration and optimisation in combination with economic evaluation Operational characteristics, risk analysis Special features for CFB boiler design are being addressed Test in small-scale CFB combustion test rig 8

9 Work packages WP 3.5 Oxyfuel combustion pilot testing Combustion tests in semi-technical scale (500 kw) (test facility) operational testing, alternative designs etc. as preparation for demonstration WP 3.6 Oxyfuel validation Preparation for large-scale pilot plant demonstration of oxyfuel PF and/or CFB boiler Tollgate decision after 24 month IF OK then long-term testing in 30 MW PF boiler and/or 1 MW CFB boiler pilot testing in phase 2 9

10 Test facilities in WP 3.1 Direct O2 injection Pilot burner Primary/secondary register air/o2/co2 fan FI TI mixing point O2/flue gas pre-heater Air inlet feeding system carrier air primary air secondary air FI FI Cylindrical furnace SC Measurement ports R1, R2...R7 Wet flue gas recycle FI Dry flue gas recycle FI T1 T2 burner 0 m insulation Cooling tube 1/ mm TI PIC SC FI stack T3 T4 electrically heating port for pyrometer measurements 1,55 m O2 C3 H mm Flue gas cooler TC TC Flue gas condenser TI Stack gas T5 ceramic tube O 200 mm 2,5 m candle filter gas analysis (O 2, CO 2, CO, NO x, SO 2 ) char sampling Cooling water 100 kw oxyfuel test rig at Chalmers Gas and coal fired 20 kw test rig at U. Stuttgart Coal fired 10

11 Highlights WP 3.1 Experimental work in 20 kw coal-fired test rig Measurements of combustion characteristics and emissions behaviour for dried lignite and a bituminous coal during air firing and oxyfuel conditions (27%O2) are finished. 11

12 Highlights WP 3.1 Experimental work in 100 kw gas-fired test rig Measurements of combustion characteristics and emissions behaviour for propane during air firing and oxyfuel conditions (27%O2) are finished. Work packages 1 12

13 One of the investigated concepts for the 1000 MW oxyfuel lignite plant Stream s Steam Water Lignite Ash N2, NOx, O2, Ar Unit 500 ESP + FG Clean-up (VAB) ESP Flue gas fan Flue gas condenser Wet ESP Dehydration H20 Condensed water O2 + Ar N2 N2+H20 T EG recirculation Flyash Inerts vent CO2 XX% Primary recycle Unit Unit 1300 Inerts removal(vab)+ CO2 compression(air Liquide) Secondary recycle IP steam to coal dryer Flue gas condensate Unit 100 Coal Ash Handling (VAB/RW E) Preheated N2 to molecular sieves TRIFLUX heat exchanger Unit 200 Boiler Island (Alstom) IP steam To R/H HP steam Unit 700 Steam Turbine Island (Alstom) Lignite G Mill Vapour condensate Condensate to steam cycle Dried lignite Ash Handling Bottom Ash Feed water Make-up water Pneumatic fuel transport O2 + Ar N2 + H20 N2 + H20 Unit 1100 Cryogenic ASU (Air Liquide) Dest. Air Molec ular sieves O2 + Ar DCAC DCWC Water to DCWC Feed water preheating High Level Conceptual PFD, 1000 MWe Lignite Fired Oxy-Combustion Power Plant Work packages 1 13

14 14

15 Efficiency of air-fired and oxyfuel plants Net efficiency (%LHV) Oxyfuel efficiency penalty of 7-9 %-points MW PF bit., ref. 600 MW PF bit., oxy 1000 MW PF lig., ref PF MW lig., oxy. 380 MW PF lig. ref 380 MW PF lig, oxy 445 MW CFB bit., ref. 445 MW CFB bit. oxy MW PF bit., ref. 600 MW PF bit., oxy 1000 MW PF lig., ref PF MW lig., oxy. 380 MW PF lig. ref 380 MW PF lig, oxy 445 MW CFB bit., ref. 445 MW CFB bit. oxy 15

16 CO 2 avoidance cost CO2 avoidance 25 CO2 avoidance ( /t) All studied cases approximately meet the targeted CO 2 avoidance cost of 20 /t CO 2 under evaluated main conditions CO2 avoidance cost ( /t, base case, 25 y CO2 avoidance cost ( /t, base case, 40 y MW PF bit., ref. 600 MW PF bit., oxy 1000 MW PF lig., ref PF MW lig., oxy. 380 MW PF lig. ref 380 MW PF lig, oxy 445 MW CFB bit., ref. 445 MW CFB bit. oxy Work packages 2 16

17 500 kw test facility at U. Stuttgart vertical furnace reduction zone burner coal + primary air additional fuel + conveyor air secondary air, flue gas recirculation in-flame measurement : O 2, CO 2, CO, NO X, C m H n, temperature reburning fuel burnout air coal mill, primary gas/ O 2 secondary, main combustion gas staging gas re-circulated part-stream of flue-gas oxygen supply ` O 2 burnout zone flue gas emissions : O 2, CO 2, CO, NO X, C m H n, temperature SCR Catalyst ESP to stack bag filter video control slag and ash > 100 µm fly ash samples : - particle size - burnout - ash analysis - trace element analysis - melting behaviour = 400 C = 200 C = 150 C Work packages 2 17

18 Oxyfuel pilot testing in phase 2 of ENCAP The Oxyfuel boiler technology subproject has nominated two candidates for pilot testing in phase 2 Phase 2: August 2006-February MW th Oxyfuel PF plant New-built plant located next to the Schwarze Pumpe power station Investment decision taken by Vattenfall in May MW th Oxyfuel CFB plant Based on modifications to an existing test-facility Decision on which of the pilot options that will be financed within the ENCAP project will be taken the next few months 18

19 30 MW oxyfuel pilot preliminary layout 19

20 Construction area 20

21 ENCAP WP 3.4 Oxygen-Fired CFB 21