Energy integration and hydrodynamic characterization of dual CFB for sorption looping cycles

Energy integration and hydrodynamic characterization of dual CFB for sorption looping cycles Luis M Romeo, Pilar Lisbona, Yolanda Lara, Ana Martínez 1st Meeting of the High Temperature Solid Looping Cycles Network Oviedo, Spain, September 2009

INDEX Energy integration of sorption looping systems Objectives Sama s rules applied to CO2 capture Results Conclusions Hydrodynamic characterization of dual CFB Objectives Test facility characterization Conclusions

Energy integration of sorption looping systems Objectives: Design a proper integration between CO 2 capture sorption looping systems with a commercial installation in order to: Reduce the cost of CO 2 capture Increase overall (CO 2 capture system + power plant) efficiency Detect key points and variables to improve by detailed research Fit the system integration depending on sorbent performance Help to select the operational variables optimum values Theoretical analysis and process simulation

Energy integration of sorption looping systems Sama rules applied to CO 2 capture: 1. Don't use excessive large or excessively small thermodynamic driving forces in the CO 2 capture integration 2. Minimize the mixing of streams, into the existing system or between capture system and existing or new designed power plant, with differences temperature, pressure or chemical composition 3. Don't discard heat from the capture process and CO 2 conditioning at high temperatures to the ambient, or to cooling water 4. Don't heat refrigerated streams, from the capture process, oxygen production or from the power plant, with hot streams or with cooling water,

Energy integration of sorption looping systems Sama rules applied to CO 2 capture: 5. When choosing streams for heat exchange in the CO 2 capture process or between CO 2 capture and power plant, try to match where the final temp of one is close to the initial temp of the other 6. When exchanging heat between two streams, the exchange is more efficient if the flow heat capacities of the streams are similar. If there is a big difference between the two, consider the splitting the stream with the larger flow heat capacity 7. Minimize the use of intermediate heat transfer fluids when exchanging heat between two streams 8. The more valuable heat in the capture system (or refrigeration, in oxygen production and/or CO 2 conditioning) is, the further its temperature from the ambient is

Energy integration of sorption looping systems Sama rules applied to CO 2 capture: 9. The economic optimum ΔT at a heat exchanger decreases as the temperature decreases, and vice versa 10. Minimize the throttling of steam, CO 2, or other gases 11. The larger the mass flow, the larger the opportunity to save (or to waste) energy 12. Use simplified exergy (or availability) consumption calculations as a guide to CO 2 process modifications 13. Some Second Law inefficiencies cannot be avoided unlike others. Concentrate on those which can.

Energy integration of sorption looping systems New installations. Objectives: Optimum CO 2 capture cost evaluation 86.5% of CO 2 avoided and CO 2 capture cost around 15.7 /ton CO 2 Energy Conversion and Management 49 (2008) 2809 2814

Energy integration of sorption looping systems New installations. Objectives: Help to select the operational variables optimum values Chemical Engineering Journal 147 (2009) 252 258 Minimization of tco 2 avoided cost is achieved with high CaO/CO 2 molar ratio and low purge percentages. Molar ratios about 5 require a minimum purge of 1%

Energy integration of sorption looping systems New installations. Objectives: Fit the system integration depending on sorbent performance Reference CaCO 3 : 6 /t With high Ca/C ratio small scope for expensive sorbents Fuel Processing Technology 90 (2009) 803 811

Energy integration of sorption looping systems Conclusions Very competitive capture cost of Calcium looping systems, lower than 15 /tco 2 Minimization of avoided cost requires high CaO/CO2 molar ratios and low purge percentages. Molar ratios about 5 require a minimum purge of 1% High solid circulation is needed It is necessary to fit sorbent type and application Cheaper sorbents for low quality fuels (high ash and sulphur content) Expensive sorbents for high quality fuels (low ash and natural gas)

Hydrodynamic characterization of dual CFB Objectives: Increase the knowledge about (very high) solid circulation in interconnected circulating fluidized beds Improve the system performance with design modifications 2 CFB and 2 BFB as seals Test Facility for the Hydrodynamic Characterization of two CFB for Ca Looping Systems

Carbonation Reactor Calcination Reactor Height = 4 m Height = 4 m Diameter = 170 mm Diameter = 160 mm SOLIDS Iv = 1-10 kg Iv = 1-10 kg T = 20º C T = 80º C P = atm pressure P = atm pressure FORWARD LOOP-SEAL BACKWARD LOOP-SEAL Operating Parameters Gs = 0.2 4.2 kg/m 2 s Solid particles Density = 2700 kg/m 3 Ug CR = 1.5-3 m/s Average size = 280 μm Ug CL = 1.5-3 m/s Beds average size = 300 μm Ug LS = 0.04 0.1 m/s LS average size = 185 μm h SP = 0.6 1.1 m AIR Fluidizing gas Minimum fluidization CARBONATOR CALCINER Gas = Air CR density = 1.20 kg/m 3 CL density = 1.03 kg/m 3 Umf LS = 0.005 m/s ɛmf LS = 0.4753

Riser Characterization Regime Transition Characteristic velocities dp mean U mf U t U c U ff 280 μm 0.07-0.17 m/s 0.47-0.56 m/s 1.03-1.30 m/s 1.30-3.00 m/s

Iv [kg] v_riser [m/s] P_riser [mbar] h_sp [m] 5 10 1 2,5 30 90 0,65 1,15

3,00 2,50 2,00 1,50 1,00 0,50 0,00 10 mbar 120 cm V loop seal 0 20 40 60 80 100 120 A B C h [m] 0,81 0,84 1,12 v_ls [m/s] 0,0605 0,0836 0,0879 Iv_riser [kg] 8,94 9,02 7,19 v_riser [m/s] 1,29 1,92 2,36 P_riser [mbar] 46,60 57,37 70,19 Gs [kg/m 2 s] 0,29 1,46 1,39 A B C h [m] 0,81 0,84 1,12 v_ls [m/s] 0,0605 0,0836 0,0879 Iv_riser [kg] 8,94 9,02 7,19 v_riser [m/s] 1,29 1,92 2,36 P_riser [mbar] 46,60 57,37 70,19 Gs [kg/m 2 s] 0,29 1,46 1,39 C

h [m] 4 3,5 3 CR F-LS CL B-LS h [m] 4 3,5 3 CR F-LS CL B-LS 2,5 2,5 2 2 1,5 1,5 1 0,5 Solid inventory 1 G s = 0.44 kg/m 2 s 1 0,5 Solid inventory 2 G s = 3.84 kg/m 2 s 0 0 1010 1020 1030 1040 1050 1060 1070 1080 Δp [mbar] 1010 1020 1030 1040 1050 1060 1070 1080 Δp [mbar] Measured superficial velocities Uo CR = 2.42 m/s Uo CL = 1.83 m/s Uo F-LS = 0.066 m/s Uo B-LS = 0.059 m/s Calculated voidages ɛ F-LS = 0.49 ɛ B-LS = 0.48 Measured superficial velocities Uo CR = 2.33 m/s Uo CL = 2.34 m/s Uo F-LS = 0.053 m/s Uo B-LS = 0.052 m/s Calculated voidages ɛ F-LS = 0.57 ɛ B-LS = 0.49

Hydrodynamic characterization of dual CFB Conclusions: High solid circulation is important in looping systems Ongoing activities to characterize interconnected CFB s Seal and recirculation have a great influence Pressure maps and solid circulation depending on superficial gas velocities (risers and loop-seals)