Coupling of power generation with syngas-based chemical synthesis

Transcription

1 Coupling of power generation with syngas-based chemical synthesis Clemens Forman, Matthias Gootz, Christian Wolfersdorf, Bernd Meyer Institute of Energy Process Engineering and Chemical Engineering, TU Bergakademie Freiberg 4th June 06, Cologne, Germany

2 OUTLINE. Background and motivation. Power generation cases 3. Coupling interfaces 4. Modeling results 5. Summary

3 . BACKGROUND AND MOTIVATION lignite-fired power plant 650,00 MW(el) electric grid renewable energy sources lignite coal combustion flue gas path steam cycle flue gas, ash, gypsum electric energy drying residual gas water electrolysis 50 MW(el) Annex plant auxiliaries steam O 00 MW(th) carbon residue coal gasifier entrained-flow (EFG) fluidized-bed (FBG) water scrubbing CO-shift sour gas CO /H S scrubbing waste water pretreatment CO Fischer Tropsch synthesis MeOH synthesis H MtG synthesis MtO synthesis small-scale chemical synthesis wax, diesel gasoline olefins 3

4 . POWER GENERATION CASES Existing power plant Design data Future power plant built in 970s to be built 00+,75 MW rated thermal input* x,55 MW (30 % dry lignite) 67 t/h coal demand x 450 t/h 650 MW gross electric output,00 MW 607 MW net electric output,046 MW 37.7 % gross efficiency* 47.6 % 35. % net efficiency* 45.3 %,853 t/h live steam generation x,387 t/h 70 bar; 530 C live steam parameter 85 bar; 605 C 34/30 bar; 300/540 C cold/hot reheat steam 56/5 bar; 340/60 C 66 mbar condenser pressure 35 mbar wet cooling tower cooling system hybrid cooling tower (natural draft) (forced draft) * thermal input / efficiencies based on LHV 4

5 . POWER GENERATION CASES Power plant modeling pressure drops Steady-state simulation Part load performance sliding pressure efficiency curves Simulation mode flue gas path plant modeling steam cycle Existing power plant Reference case: design Annex integration: off-design Future power plant Reference case: design Annex integration: design boiler curves heat losses auxiliary power 5

6 net plant efficiency change (%-points) specific auxiliary power (%) net plant efficiency change (%-points) specific auxiliary power (%) Coupling of power generation with syngas-based chemical synthesis. POWER GENERATION CASES Key performance data: net plant efficiency; specific auxiliary power 0, ,0 0, , , ,5-0, , , ,0-0, , , , , ,5 -, , , ,0 -, , , , net efficiency change specific auxiliary power 5.5 5, ,0 -, , , net efficiency change specific auxiliary power 4, , , , , ,5-4.5, boiler capacity (%) boiler capacity (%) existing power plant: % load future power plant: % load (per block) 6

7 3. COUPLING INTERFACES Existing power plant ECO Target: coupling interfaces require little constructional effort only CAPH RHT SHT HP IP LP ~ 50 Hz MP steam: injection into the cold reheat pipeline air ESP EVAP HP FWH LP steam: installation of an additional feedwater heater bypassing the existing LP feedwater heating section Carbon residue & gases: combustion / thermal treatment in the after-burning section of the furnace IDF FGD clean gas DM lignite residue & gases FWT LP FWH BFWP CP C CT ANNEX CWP 7

8 3. COUPLING INTERFACES Future power plant clean gas air ECO Target: investigation of different coupling scenarios FGD FGTS I CAPH II RHT SHT HP IP LP ~ 50 Hz MP steam: injection into feed line of BFWT/FWH and FBD I EVAP x HP FWH LP steam: feedwater heating and injection into feed line of FBD IDF FBD DM lignite residue & gases FWT BFWP BFWT C 3 Carbon residue & gases: after-burning section (one/both blocks) ESP II CAPH HP-ABEco LP-ABEco LP FWH CP 3 C CWP CT ANNEX 8

9 thermal rating (MW) FT MTO MTG Coupling of power generation with syngas-based chemical synthesis 3. COUPLING INTERFACES Residual & sour gases: positive pressure; ~30 C; major components (at STP) 9.4 9,4,7.7 3, , 7. 6, , 0,6 0.6 Sour gas: vol.-% CO..7 vol.-% H S vol.-% CO+H ppmv COS 8 ppmv NH 3 MeOH synthesis: purge gas (~79 vol.-% H ) light ends (~3 vol.-% CH 3 OH) MtG synthesis: off gas (~9 vol.-% C-C4)., 9,7 9.7 Carbon residue (FBG only): atm; ~00 C,.,0.0,0.0 residual & sour gases 34 wt.-% carbon; 66 wt.-% ash 4.8 MW thermal input (.5 MJ/kg LHV) Flue gas: vol.-% [existing plant] and 0..6 vol.-% [future plant] SO : 0-53 mg/m³ (STP) [existing plant] and mg/m³ (STP) [future plant] CO : 6-89 g/kwh(el) [existing plant] and 5-7 g/kwh(el) [future plant] 9

10 thermal rating (MW) FT MTO MTG thermal rating (MW) FT MTO MTG Coupling of power generation with syngas-based chemical synthesis 3. COUPLING INTERFACES MP steam: 40 bar; 53 6 C LP steam: 5 bar; C 5.8 5,8 5, ,0 6.0,4.4 LP steam 38, , , , , 44. 9, 9. 4, , , ,9 6, , 4. 5, 5. 56, 56. 9, , , , ,9 8.9 MP steam 77,

11 thermal rating (MW) FT MTO MTG ሶ ሶ ሶ ሶ Coupling of power generation with syngas-based chemical synthesis 3. COUPLING INTERFACES Total heat input: steam; gases; carbon residue 83, , , 09, Power plant efficiency stand-alone (LHV) η Power = P el [ P aux ] ሶ Q C 05, 05. el: electric aux: auxiliaries 98, ,3 77, , , , , Power plant efficiency with Annex integration η Power+Annex = P el [ P aux ][ Q S,export ] Q C + Q S,import Q W + Qሶ G + Qሶ R C: coal S: steam W: feedwater G: gases R: carbon residue

12 net plant efficiency change (%-points) net plant efficiency change (%-points) Coupling of power generation with syngas-based chemical synthesis 4. MODELING RESULTS Net plant efficiency: reference case vs. Annex integration 0, , , , , , , , , , , , , , , , ,0-4.0 EFG-MTG FBG-MTG -4,0-4.0 EFG-MTG FBG-MTG -4,5-4.5 EFG-MTO FBG-MTO -4,5-4.5 EFG-MTO FBG-MTO -5,0-5.0 EFG-FT FBG-FT -5,0-5.0 EFG-FT FBG-FT -5,5-5.5 reference (existing plant) -5,5-5.5 reference (future plant) -6, , boiler capacity (%) boiler capacity (%) existing power plant: (00 %) (50 %) future power plant: (00 %) (40 %)

13 coal savings compared to reference (%) coal savings compared to reference (%) Coupling of power generation with syngas-based chemical synthesis 4. MODELING RESULTS Coal savings: heat input by Annex integration results in less coal demand (and CO emissions) EFG-MTG EFG-MTO EFG-FT 8 EFG-MTG EFG-MTO EFG-FT 7 FBG-MTG FBG-MTO FBG-FT 7 FBG-MTG FBG-MTO FBG-FT existing power plant future power plant boiler capacity (%) boiler capacity (%) existing power plant: FBG-MTG - -5 g CO / kwh(el) future power plant: FBG-MTG - -6 g CO / kwh(el) 3

14 clean gas 4. MODELING RESULTS air ECO air ESP IDF FGD clean gas I HP IP LP Steam injection: impacts and possible limitations over plant load example: FBG-MTG ~ MP steam injection into cold reheat pipeline CAPH DM RHT SHT EVAP ECO HP FWH BFWP LP-ABEco lignite - Injection relative II % % FWT FGD ESP LP 8 th International Freiberg Conference, 6 FWH June 06 existing power plant HP IDF FGTS IP I CAPH LP CAPH ~ 50 Hz Cold reheat pipeline heat stream (MW) mass flow (kg/s) FBD HP-ABEco Reference case 790, Annex integration 80, Injection absolute 53 9 II lignite CT DM RHT SHT EVAP x MP steam injection into feed line of BFWT/FWH HP FWH FWT LP FWH BFWP CP BFWT C 3 C 50 Hz BFWT/FWH feed line heat stream (MW) mass ANNEX flow (kg/s) 3 future power plant Reference case DUO MONO Annex integration compared to reference conditions - Injection absolute 53 CWP 9 - Injection relative DUO 00 3 % 9 37 % MONO % 73 % ANNEX CT 4

15 relative net electricity generation (%) Coupling of power generation with syngas-based chemical synthesis 5. SUMMARY reference Annex integration Annex integration including electrolysis 00 Strengths: Annex integration results in coal 80 savings (and less CO emissions) 60 Weaknesses: Slight efficiency loss compared to reference plant cases 40 Opportunities: Improvement of load elasticity via 0 Annex integration 0 existing power plant SINGLE future power plant DUO future power plant MONO existing power plant SINGLE future power plant DUO future power plant MONO Threats: Possible limitation of steam injections towards minimal boiler capacity Note: Annex integration averaged amongst all scenarios 5

16 ACKNOWLEDGEMENT Project Concept studies of coal-based Polygeneration-Annex-plants (03ET704A) Supported by: Participating companies: RWE Power AG Forschung und Entwicklung 6

17 THANK YOU FOR YOUR ATTENTION! For enquiries or further questions, please contact: Clemens Forman Phone: +49 (0) Fax: +49 (0) Website: 7

18 APPENDIX References Nomenclature (power plant) C. Wolfersdorf, K. Boblenz, R. Pardemann, B. Meyer; Syngasbased annex concepts for chemical energy storage and improving flexibility of pulverized coal combustion power plants; Applied Energy 56 (05) 68-67; doi:0.06/j.apenergy ABEco BFWP BFWT air bypass economizer boiler feed water pump boiler feed water turbine EVAP FBD FGD evaporator fluidized-bed drying flue gas desulfurization M. Gootz, C. Forman, B. Meyer; Coal-to-Liquids: An attractive opportunity for improved power plant capacity utilization?; 8th International Freiberg Conference on IGCC & XtL Technologies Innovative Coal Value Chains, Cologne, Germany, C CAPH CP condenser combustion air preheater condensate pump FGTS FWH FWT flue gas transfer system feed water heating feed water tank C. Forman, R. Pardemann, B. Meyer; Differentiated evaluation of the part load performance of an industrial CHP; COAL-GEN Conference 05, Las Vegas, Nevada/USA, CT CWP DM cooling tower cooling water pump drying mills HP IDF IP high pressure induced draft fan intermediate pressure ECO economizer LP low pressure ESP electrostatic precipitator MP medium pressure Nomenclature (Annex plant) EFG Entrained-flow gasifier RHT SHT reheater superheater FBG Fluidized-bed gasifier FT Fischer-Tropsch synthesis MTG Methanol-to-Gasoline synthesis MTO Methanol-to-Olefins synthesis 8