9 th Trondheim Conference on CO 2 Capture, Transport and Storage, 12-14 June 2017 SECOND GENERATION CALCIUM LOOPING SYSTEM WITH BIOMASS COMBUSTION IN THE CALCINER I. Martínez*, B. Arias, J.C. Abanades Spanish Research Council (ICB and INCAR from CSIC) *imartinez@icb.csic.es
OUTLINE Description of standard and 2nd generation CaL systems Process simulation assumptions Performance results and conclusions
Standard post-combustion CaL process CPU CO 2 for Flue gas transport and with low storage CO 2 CO 2 Energy content Energy CO 2 recycle ASU Oxygen Air Power Flue plant gas Coal CaO CaCO 3 Purge Limestone Carbonator Calciner Coal Air 650ºC >900ºC EXISTING POWER PLANT NEW OXY-FIRED CFB POWER PLANT Low energy penalty /low cost per ton CO 2 captured Benefits of Low cost sorbent precursor Purge of CaO: synergies with cement industry and others (i.e. desulfurization ) Ca-looping Pre-treatment of flue gas no needed (SO 2 co-capture) Benefits and limitations of large scale CFBCs (including oxy-CFB)
Standard post-combustion CaL process STANDARD Ca LOOPING CONFIGURATION: Oxy-fuel combustion in the calciner C PU C O 2 for Natural limestone used a sorbent precursor Flue gas trans port and Circulating fluidized bed combustors with low storag e C O 2 C O 2 content C O 2 recycle AS U Oxyg en Power Air Flue gas plant C oal Purg e L imes tone C arbonator C alciner C oal Air 650ºC >900ºC Disadvantages of oxy-fuel combustion in the calciner: -Energy penalty due to oxygen production (~200 kWhe/tO 2 ) -Large investment cost -Low flexibility to load changes Improvements of Ca-looping: -Advanced process configurations without oxy-combustion (i.e. Indirect heat transfer through metallic walls/heat pipes, high temperature solid heat carriers …) -Second generation CaL processes (Reducing heat demand in the calciner)
Second generation post-combustion CaL process HEAT DEMAND IN THE CALCINER Minimize or reduce CO 2 -recycle: - Calcination of CaCO 3 - 20% REDUCTION by increasing oxygen - Sensible heat of recycled CO 2 contents up to 80%v. - Less oxygen needed (less OPEX) - Sensible heat of circulating solids - Smaller ASU and calciner sizes (less CAPEX) CaO 2 : Calcium looping CO 2 capture technology with Effect of O 2 in the comburent on calciner heat demand in a CaL standard scheme extreme oxy-coal combustion conditions in the calciner 120 European Union RFCS project: 2014-2017 Sensible heat with flue gas Sensible heat to solids Heat demand in the calciner (%) 100 Calcination heat 80 Demonstration in a 60 pilot (2-3 MW th ) of 40 ultra-rich O 2 calcination 20 technology 0 25 30 35 45 55 65 75 85 100 %O 2 in the comburent *T carb =650ºC, T calc =910ºC;X ave =0.15, X carb =0.11;T comburent : 300ºC
Second generation post-combustion CaL process HEAT DEMAND IN THE CALCINER - Increase the temperature of the solids entering into the calciner - Calcination of CaCO 3 - Improve the activity of the solid - Sensible heat of recycled CO 2 - Sensible heat of circulating solids Loop seal-Recarbonator Improve sorbent activity by means of recarbonation : -No energy penalty associated -No influence on sorbent mechanical properties -No need of additional reagents in the process -Less limestone consumption (less OPEX) The sorbent activity increases up to 8-10 net points due to recarbonation Diego et al. 2016 . Experimental testing of a sorbent reactivation in La Pereda 1.7 EU RFCS project: 2012-2015 MW th calcium looping pilot plant Int. J. Greenhouse Gas Control , 50, 14-22
Second generation post-combustion CaL process 2 ND GENERATION Ca LOOPING CONFIGURATION: Pure oxygen used in the calciner Sorbent improvement by means of recarbonation CO 2 for Flue gas transport and with low storage CO 2 CO 2 content CO 2 Carbonator recycle Calciner Calciner 650ºC >900ºC < 900ºC Re-carbonator ≈ 800ºC Purge ASU Flue Limeston Power e gas plant Air Oxygen Biomass Coal Coal Air Contribute to negative CO 2 emission factors Avoid typical operational problems (corrosion and deposition in heat exchange surfaces, reduction of unburnt emissions, minor organic emissions ultimately captured in the CPU…)
OUTLINE Description of standard and 2nd generation CaL systems Process simulation assumptions Performance results and conclusions
Process modeling – General assumptions STANDARD & 2 nd GENERATION Ca LOOPING CONFIGURATIONS CPU CALCINER Flue gas with low 95% calcination efficiency CO 2 to stack Existing CFB air-fired SC 3.5% O 2 at outlet plant h net =43.3% 1000 MW th fuel input CO 2 FG with 14% CO 2 CO 2 Condensate recycle Calciner Carbonator ASU Oxygen Power Air plant Coal Flue Limestone gas AIR SEPARATION UNIT Coal Air 95% O 2 purity (Ar,N 2 ) Purge Consumption: 200 kWh/t O2 CARBONATOR & CALCINER Reactor models implemented RPM kinetic model for the carbonation reaction CO 2 carrying capacity decay law ( X ave ) 99 % SO 2 capture efficiency
Process modeling – General assumptions STANDARD & 2 nd GENERATION Ca LOOPING CONFIGURATIONS CO 2 COMPRESSION AND PURIFICATION UNIT CPU CALCINER Flue gas with low Single flash auto-refrigerated process 95% calcination efficiency CO 2 to stack Existing CFB air-fired SC Vent gas containing 3-4% inlet CO 2 3.5% O 2 at outlet plant ≈ 115 kWh/ton CO2 h net =43.3% Vent 1000 MW th fuel input 20 bar gas Rich CO 2 30ºC FG with 14% CO 2 CO 2 CO 2 -54ºC Condensate recycle Calciner Carbonator IC compressor Drier -45ºC Knock-out 23ºC ASU 89 bar 150 bar CO 2 for drum transport pump Oxygen Power Air Multi- plant flow HX IC compressor Coal Flue Romano, M.C. Int. J. Greenhouse Gas Control, 2013, 18: 57-97 Limestone gas AIR SEPARATION UNIT Coal Air 95% O 2 purity (Ar,N 2 ) Purge Consumption: 200 kWh/t O2 CARBONATOR & CALCINER Reactor models implemented RPM kinetic model for the carbonation reaction CO 2 carrying capacity decay law ( X ave ) 99 % SO 2 capture efficiency
Process modeling – General assumptions 2 ND GENERATION Ca LOOPING CONFIGURATION CPU Flue gas with low CO 2 to stack CO 2 Condensate CO 2 Carbonator recycle Calciner Re-carbonator Purge ASU Flue gas Limestone Power plant Air Oxygen Biomass Coal Air RE-CARBONATOR CaCO 3 content: X carb,R =0.02 + X ave,R Excess CO 2 [i.e. +50% over that needed for (X carb,R - X ave,R )] Diego et al. 2014. I&EC Research 53, pp. 10059 - 10071
Process modeling – General assumptions HEAT RECOVERY IN THE Ca LOOPING SCHEMES CPU Flue gas with low 350-60ºC T calc – 350ºC CO 2 to stack T carb – 100ºC CO 2 CO 2 Condensate recycle Energy Calciner Carbonator ASU 25-200ºC T carb Power Oxygen Air plant Coal Flue Limestone gas T calc – 150ºC Coal Air Purge Air-fired SC plant 433 MW
Process modeling – General assumptions HEAT RECOVERY IN THE Ca LOOPING SCHEMES USC STEAM CYCLE Heat recovered in the EVA, ECO, SH, RH Some of the HP & LP FWH replaced RH SH EVA ECO Romano, M.C. Int. J. Greenhouse Gas Control, 2013, 18: 57-97
Process modeling – Operating conditions STANDARD CaL SCHEME SECOND GENERATION CaL SCHEME C O 2 for Flue gas C PU C O 2 for trans port and with low Flue gas trans port and CO 2 storag e C O 2 content with low storag e C O 2 C O 2 C O 2 content C O 2 Carbonator Calciner recycle recycle 650ºC < 900ºC Re-carbonator AS U 750-800ºC Purg e Oxyg en Power Air AS U Flue gas Flue gas Power L imes tone plant C oal Air plant Purg e Oxyg en L imes tone C arbonator C alciner C oal Air 650ºC >900ºC Biomass C oal Air Carbonator CO 2 capture efficiency: 90% Carbonator CO 2 capture efficiency: 80% Carbonator temperature: 650ºC Carbonator temperature: 690ºC Calciner temperature: 910ºC Calciner temperature: 890ºC Fuel in the calciner: high-rank coal Fuel in the calciner: woody biomass (0.7% S, 3% H 2 O and 6% ash; LHV=33 MJ/kg) (0.02% S, 15% H 2 O and 1% ash; LHV=16 MJ/kg) Oxygen content in the oxidant: 40%v. Oxygen content in the oxidant: 95%v. Ratio F 0 /F CO2 : 0.12 (0.6 kg /kg coal existing PP) Ratio F 0 /F CO2 : 0.05 (0.3 kg /kg coal existing PP) CO 2 carrying capacity decay law typical for Improved CO 2 carrying capacity decay law limestone (X r ≈ 7-8%) due to recarbonation (X r ≈ 16 -17%) Grasa et al. 2014. Energy & Fuels 28, pp. 4033 - 4042
OUTLINE Description of standard and 2nd generation CaL systems Process simulation assumptions Performance results and conclusions
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