Calcium Looping activities at IVD

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1 Institut für Verfahrenstechnik und Dampfkesselwesen Institute of Process Engineering and Power Plant Technology Prof. Dr. techn. G. Scheffknecht Calcium Looping activities at IVD Anja Schuster Institute of Process Engineering and Power Plant Technology Stuttgart University 4th International Workshop on In-Situ CO 2 Removal (July, 6-9 th 2007 in London)

2 Content Sorption enhanced reforming Principle/advantages i Related projects Results Future activities Lime-based CO 2-capture from flues gases Principle/advantages Related projects Results Future activities Test facilities

3 Sorption Enhanced Reforming

4 Sorption Enhanced Reforming Advantages: Autothermal th process Utilisation of high moisture fuel H 2 -rich gas in-situ it sulphur capture Low tar content Char is used in the regenerator Production of pure CO 2 for storage Solid purge of CaO and ash for cement industry Biomass gasification (AER) Coal gasification (LEGS) Closed Projects - AER-GAS (EU-FP5, ZSW co-ordinator) - ISCC (EU-FP6, IVD co-ordinator) - Bio-AER (national, co-operation with ZSW) - C2H (EU-RFCS, IVD co-ordinator) Ongoing g Projects - AER-GAS II (EU-FP6, ZSW co-ordinator) - BS-flex (national) - BS-flex (national)

5 Polygen: Electricity, H 2, syngas & cement Polygeneration (gas composition can be controlled by the SER process) Large part of CO 2 from cement industry can be captured fuel SER Gasifier CaCO 3 CaO char H 2 -rich syngas electricity syngas hydrogen limestone Regenerator CO 2 -rich gas storage purge cement industry

6 Sorption Enhanced Reforming - Selected results -

7 AER (biomass gasification) batch mode Pilot test- batch mode H 2 ~ 78 vol.-% CO 2 < 12 vol.-% Low tar content ga as compo osition [V Vol.-%] fuel: wood pellets; T 650 C; s/c = 2,8 ta ars [gc/m³ ³] duration [h] AER conventional

8 AER (biomass gasification) several cycles fluidisation medium 100 steam 650 C; s/c=2,5; fuel: wooden pellets; bed: dolomite, CaO/C ~ 1 air N t in mol-% (dry basis s) gas conten N 2 H 2 tar CO 2 CO 1,5 1 0,5 C/m³ tar co ontent in g 0 CH 4 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 time from start [h:mm] 0

9 AER (biomass gasification) parameter variation Influence of temperature and s/c-ratio on H 2 -content ,5 74,7 75,4 73,1 73,4 74,8 75,1 69,8 62,3 63,5 71,6 62,1 ration (Vo ol%) concent H , ,5

10 (vol%, db, N 2 -fr ree) Concentration LEGS (coal gasification) Semi-batch tests under pressure: 40 min steady-state H 2 ~ 85 vol.-% (88% of equilibrium) i CO 2 < 8 vol.-% Low tar content (0.5-2 g/nm 3 ) NCV ~ MJ/Nm 3 Over 10 limestones tested; most show similar behaviour Equlibrium H 2 concentration Gas Sampling Blocked End of 3.5 bar, 720 C CO2 CH4 End of CO 2 Capture CO 2 Capture Time (min) CO H2 Pressurized fluidized bed reactor reactor air 1 heating devices air preheater 1 cyclone cyclone ash Steam Coal feeding P = 13 bar D = 10 cm 5-10 kg/h

11 LEGS (coal gasification) - results pture, % rbon Cap Car Pressure (bar) ~ 0% CO 2 in product gas possible H2-production and tar concentration measured for differents temperature and pressure levels Recommended conditions for sufficient coal conversion, CO 2 capture, gas quality: C, bar

12 Future research activities at IVD Demonstration of production of H 2 -rich gases in continuous operation (dual fluidised bed system) Construction o and operation o of 200 kw pilot plant Testing of different fuels and limestones in continuous operation Determination of fuel conversion depending on process conditions Determination of optimal circulation rates Production of product gas suitable for gas engines, gas turbines or synthesis Development of O 2 -calcination for production of CO 2 -rich gas for storage (coal gasification) Up-scaling of the process

13 Lime based CO 2 -capture from flue gases

14 Lime based CO 2 -capture from flue gases Closed Projects - Feasibility study (COORETEC, co-operation with EST-TU Darmstadt) Ongoing Projects - C3-CAPTURE (EU-FP6, IVD co-ordinator) - CATS (funded d by industrial i partner) Advantages: Natural sorbent material Efficiency penalty less than 6 % Capture costs less than 20 /t CO2 (comparable to oxyfuel process and half of amine scrubber costs) No changes in boiler design necessary Suitable for retrofitting Additional power production for retrofitting case

15 Lime based CO 2 -capture from flue gases - Selected results -

16 Development of CFB carbonator reactor model Motivation Construction ti of 2 carbonate looping facilities at IVD, University it of Stuttgart tt t : Externally heated lab-scale dual fluidized bed carbonator (FP6 C3-Capture project) 200 kw th multi-purpose DFB facility for investigation of Absorption Enhanced Reforming and Carbonate Looping (financial support from: State of Baden- Württemberg, EnBW Kraftwerke AG, ALSTOM Power) Basic reactor model required for preliminary design of the fast fluidized bed carbonator in order to achieve 70-85% CO 2 capture: Bed mass (W CaO ) Fraction of free active CaO (f a ) and carbonated CaO (X carb) ). Others: temperature, velocity, particle size Circulation rate between Carbonator & Regenerator (F CaO ) and make-up limestone (F 0 ) Effect on heat balance and X limestone (F 0 ) Effect on heat balance and X max

17 IVD CO 2 capture CFB carbonator model Model inputs and outputs Hydrodynamic- Kinetic IVD CFB carbonator MODEL CO 2 lean INPUTS Reactor dimensions Inlet velocity Particle properties Bed Inventory Temperature Inlet CO 2 concentration Carbonation kinetic parameters F CaO,R F CaO,C A N N U L U S CORE ACCELERATION DENSE BED EMULSION B U B B L E A N N U L U S OUTPUTS CO 2 capture efficiency Riser entrainment Axial voidage profile Radial voidage profile Flue Gas

18 Effect of fraction of Free Active CaO (fa) Free active CaO has the strongest influence on CO 2 capture. f a = 0.2 achieves equilibrium, f a = 0.1 over 80%. f a = does not surpass 60% CO 2 capture even at ~ 102 mbar bed mass equivalent. 1 Equil. pture, E c CO 2 Cap 0,8 0,6 0,4 0, f a =0.05 D = Dense region A = Acceleration region C-A = Core-annulus region 0 D A C-A CFB Height (m)

19 CO 2 Capture as a Function of Bed Mass (W CaO ) As expected, Carbonator bed mass is an important design parameter and should be greater than ~ 80 mbar for fa > Too much bed mass has negative reprecussions: Unreasonably high particle residence times Power consumption and technical feasiblity of commercial CFB blowers. 10 1,0 Equilibrium t, E c 0,9 f a = 0.2 CO 2 Captur e at Exi 0,8 0,7 0,6 f a = 0.1 f a = f a = Requested Capture Efficiency 05 0,5 3 3,5 4 4, mbar Carbonator Bed Mass (kg) 129 mbar

20 Selection of Circulation Rate: F CaO /F CO2 Regenerator heat demand more than 40% of total at F CaO /F CO2 > 13 for f a =0.05 Percentage of total heat demand rises with increasing free active CaO. Why? Q reg = Circulating Solids ( C) + Make-up CaCO 3 ( C) + Calcination (Make-up + Carbonator CaCO 3 ) 0,5 fa=0 fa= ,0 fa=0.1 fa= ,5 04 0,4 10,0 Q reg /Q tot Q Reg / Q reg + Q comb 03 0,3 Increasing free active CaO Note: G s from Carbonator translates to F CaO /F CO2 ~ 66 7,5 5,0 F 0 /F CO O2*10 0,2 2,5 0, F CaO / F CO2 0,0

21 f a Increases Regenerator Heat Demand Since X carb is fixed for a specific E c and F CaO, And X max = f a + X carb, Make-up limestone input, F 0, increases to meet X max requirements: X max = f(f 0 /F CaO ) 05 0,5 fa=0 fa= fa=0.1 fa= ,4 75 Q reg Q tot Q reg + Q comb Q Reg / 0,3 Recommended Process Range 50 2 (%) F 0 / F CO2 (%) F 0 /F CO 0,2 25 0, F CaO / F CO2 0

22 Implications for Carbonate Looping Design To achieve a capture efficiency, E c, between 70-85%: Temperature between C Free active CaO (f a )should be as low as possible to minimize regenerator heat demand. Realistic range: to mbar < W CaO < 130 mbar recommended (depending on f a ) F CaO /F CO2 recommended between 2.5 and 13 to minimize Q Reg G s from carbonator is too high to be directly circulated to regenerator: requires a solid flow splitting device (e.g. cone valve, L-valve) F 0 /F CO2 output of reactor model and population balance

23 Future research activities Experimental testing of the process in continuous operation (dual fluidised bed system) Construction and operation of 200 kw pilot plant Testing of different limestones in continuous operation Determination of CO 2 -capture costs and efficiency penalty based on pilot plant test conditions/results Up-Scaling of the process Design of a 20 MW demonstration plant

24 Test facilities at IVD

25 Test facilities 20 kw th lab scale test facility for continuous operation for SER and CO 2 -capture (started operation) Coupled BFB-CFB, eletrically heated (equivalent to 20 kw th ) Scaled cold model of lab scale facility (in operation) Construction of 200 kw th dual fluidised bed pilot plant for th SER: Coupled BFB-CFB CO 2 -Capture: CFB-CFB Start of operation: March 2009 Construction of scaled cold model of pilot plant Start of operation: July 2008

26 Process advantages of facility due to solid split Dual FB system with split of the flow between carbonator and calciner leads to: Control of recirculation rate Control of enthalpy flows (Energy needs of calciner) Control of residence time in beds (Provision of time for carbonation) Operation at high solid loading and velocity of CFB carbonator with adjusted (optimum) circulation rates between the beds Ability to investigate operation at: High recirculation rates with minimum make-up flows of fresh CaCO 3 (no coupling with cement plan) Low recirculation rates with large make-up flows of fresh CaCO 3 (coupling with cement plant)

27 20 kw th lab scale test facility - characteristics Unit Value CFB diameter/ height (m) m 0.07 / 12.4 BFB diameter/ height (m) m / 3.2 Volume of flue gas entering carbonator Nm 3 /h Concentration of CO 2 in the flue gas % 15 Solid residence time in carbonator min Adjustable Od Order of minutes Solid residence time in calciner min Adjustable Order of minutes

28 20 kw th lab scale test facility- SER CO 2 rich gas Calciner 900 C H 2 rich gas height: 12.4 m, diameter: 7 cm Gasifier C Height: 3 m diameter: 11.4 cm Mechanical valve Coal/biomass steam Air or O 2 / CO 2

29 20 kw th lab scale test facility - CO 2 -capture CO 2 lean flue gas 2 g CO2 rich gas Carbonator 650 C Calciner 900 C Mechanical valve Flue gas

30 Cold model of lab scale test facility Height CFB: 4.8 m Diameter CFB: 30 mm Diameter CFB: 145 mm

31 Reactor concept validated through cold model performance prediction of test plant through cold model performance Scaled inputs Cold model Outputs cold model: Riser pressure drop Ail Axial pressure profile Riser entrainment Cone valve discharge Scaling laws Scaling laws Inputs test plant Total solid inventory Regenerator pressure Riser velocity Loop seal aeration Cone valve opening Particle size Test plant Scaled outputs + CO 2 capture Efficiencyi

32 Cold model results Effect of total solid inventory on riser pressure drop ) Riser pressur re drop (mbar) chocking Min. u o Increasing Total Solid Inventory Max. u o 20 Riser operating window Unstable riser operation 0 2,2 2,4 2,6 2,8 3 3,2 3,4 Riser superficial velocity (m/sec) TSI 2.24kg TSI 2.64 TSI 2.94kg TSI 3.24kg TSI 3.64kg Larger total solid inventory makes more mass available in the riser and pressure drop increases For every total solid inventory there is a velocity operating window

33 Cold model results Predicted CO 2 capture efficiency of test plant "Ho ot" riser pres ssure drop (mbar) Cold model results are extrapolated to the pilot facility: ,4 3,6 3,8 4 4,2 4,4 4,6 4,8 5 5,2 "Hot" riser superficial velocity (m/s) 50-70% 70-80% 80-85% 85-90% Assuming: Free active CaO (%) is 012 0,12 Inlet vol. fraction of CO 2 is 15% Efficiency increases with increasing riser pressure drop and is influenced by riser velocity. Efficiencies are similar to those predicted from the model and can reach equilibrium values

34 200 kw pilot plant - characteristics Sorption enhanced reforming CO 2 -capture Gasifier Regenerator Combustor Carbonator Regenerator Height 6 m 11 m Diameter 0.33 m 0.17 m Power 200 kw 15.6 kw Fuel 44 kg/h 7.5 kg/h 6 m 11 m 11 m 0.33 m 0.23 m 0.17 m 200 kw kw 30 kg/h - 20 kg/h Limestone - 7kg/h 15kg/h 1.5-7kg/h

35 Pilot plant: biomass gasification filter H 2 -rich product gas flare Cyclone biomass 44kg/h Gasifier T=660 C Regenerat tor T=850 0 C filter flue gas steam air limestone biomass purge

36 Pilot plant: lignite gasification H 2 -rich product gas flare Cyclone lignite Gasifier T=660 C Regenerat tor T=920 0 C CO 2 -rich gas steam limestone lignite CO 2 -recirculation O 2 purge

37 Pilot plant: CO 2 capture filter CO 2 -lean flue gas flare Cyclone CO 2 -rich gas coal 30 kg/h Combust tor T=850 C Ca rbonator T=650 C limestone purge Regene erator T=9 920 C coal filter air 20 kg/h O 2 CO 2 recirculation

38 Pilot plant Cyclone Fuel dosage system Gas cooler BFB Sorption enhanced gasification Lime based CO 2 -capture Convent. Combustion/gasification Oxyfuel-combustion CFB Recirculation fan Gas pre-heater CFB

39 IVD s Calcium Looping Competencies Process modeling and steam cycle integration Aspen Plus process model Ebsilon Professional steam cycle model Economic & Technical feasibility analysis Carbonator hydrodynamic-reactor model for design Scaled cold modeling to identify stable operating regions Batch Lab-scale experience in: CO 2 capture from flue gas Sorption Enhanced Reforming (SER): Biomass / Coal at atmospheric pressure Coal up to 6 bar Lab-scale and Pilot-scale facilities for the investigation of CO 2 capture and SER under steady-state operation

40 Thank you for your attention Questions?