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Excess Enthalpy Effects on Reforming Biomass for CO2 Mitigation

This report examines the characteristics of excess enthalpy on dry autothermal reforming from simulated biogas using porous media. It explores the potential for CO2 mitigation and hydrogen generation through chemical recycling of CO2 with biomass-derived gas.

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Excess Enthalpy Effects on Reforming Biomass for CO2 Mitigation

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  1. Reforming & Gasification, Biomass-1, HPB6 Characteristics of excess enthalpy on dry autothermal reforming from simulated biogas with porous media Reporter : Ming-Pin Lai • M.P. Lai, W.H. Lai, C.Y. Chen, S.S. Su, R.F. Horng, • W.C. Chiu, Y.M. Chang • Department of Aeronautics and Astronautics, Research Center for Energy Technology and Strategy (RCETS), National Cheng Kung University, Tainan, Taiwan (R.O.C.) • Department of Mechanical Engineering, Kun Shan University, Tainan, Taiwan (ROC) Date : 2012/06/05

  2. Contents Introduction and motivation Related literature and objective Equipment details and parameters design • Preliminary achievement • Effect of excess enthalpy on reaction gas temperature • Effect of porous assisted DATR on performance index Conclusions

  3. Introduction and Motivation CO2 mitigation and H2 generation • CO2 is a valuable carbon source. The low carbon economy through chemical recycling of • CO2with an alternative renewable energy resource (ex: Biogas, Landfill, digester gas …etc). • Recycling excess CO2 from industrial gases and mobility vehicle will mitigate a major man- • made cause of globe warming. The flue gas and exhaust gas are attractive as waste heat for • endothermic reaction. Composition of biomass derived gas. Biomass Biogas Landfill Reforming (Thermal-chemical) • CO2 decomposition : CO2→CO+0.5O2 • Gasification (Boudouard) : C+CO2→2CO • CO2 reforming of CH4 : CH4+CO2 →2CO+2H2 • Reverse water gas shifting : CO2+H2 →CO+H2O • CO2 -Methanation : CO2+4H2 →CH4+2H2O Reduction (Photo-chemical) Synthesis • Advantage: • Heating value • H2-rich gas for power system (ICE/GT/*FC…etc) • Assisting combustion (Incinerator) • Syngas application • Synthesis fuel (Diesel, Gasoline, JP, DME, MeOH) • GHG reduction • Mitigation, Recycle, Reuse 1

  4. Related Literature and objective(1/2) Comparison of the Tead and TR under varying reforming parameters WH Lai, MP Lai, RF Horng, Study on hydrogen-rich syngas production by dry autothermal reforming from biomass derived gas, International Journal of Hydrogen Energy, doi:10.1016/j.ijhydene.2012.03.076. 2

  5. Related Literature and objective(2/2) Excess enthalpy (Super-adiabatic temperature) The figure shows a schematic diagram of the temperature histories of premixed combustion both without and with heat recirculation The internal heat recirculation mechanism by heat transfer. Modified after [8] 3

  6. Experimental details Schematic of experimental arrangement 4

  7. Experimental parameter design • Reforming parameters: • Fuel feeding rate : 10 L/min-CH4 • CO2/CH4 : 0, 0.33, 1 • O2/CH4 : 0.5, 0.75, 1.0 • Reforming mode : POX, DATR • Porous media specifications : • Material: OBSiC, Al2O3, ZrO2, • Cordierite, Fe-Cr-Al alloy • Structure: Ceramic foam, Honeycomb • Catalyst specifications : • Active catalyst : Pt-Rh/CeO2-Al2O3 • Support : Monolith (100cell/in2) • Loading amount : 50 g/ft3 • D × L : ψ46.2*50.0 mm2 Relationship of O2/CH4 molar ratio and reaction of enthalpy under methane reforming 5

  8. Preliminary achievement (1/3) -Photographic observation on PM assisted DATR • Temperature data show for reaction in which a PM was placed, the reformate gas temperature of each position of the catalyst could be raised to 150 to 200˚C. • The fire observation in the side views show that adding PM can reduce wall heat dissipation, which is accomplished mainly by using various heat transfer paths, which feed the heat stored in the wall back into the PM. • Images from Table (A, D) show that reactions with a PM are able to prevent the low temperature working fluid from directly entering the catalyst reaction zone, which overcomes the problems of temperature gradients in the catalyst. 6

  9. Preliminary achievement (2/3) -Effect of excess enthalpy on reaction gas temperature • PM was installed in the reaction zone, their overall reaction temperatures not only effectively were improved, but could be higher than those of the EATs. • However, the temperature curve also shows that the material of PM has made a little difference in the reformate gas temperature. • It confirmed the view that PM can achieve the excess enthalpy on a reforming reaction. • Excess enthalpy (Super-adiabatic temp.) • RGT>EAT Comparison of the equilibrium adiabatic temperature and reformate gas temperature with or without PM assisting under varying reforming parameters 7

  10. Preliminary achievement (3/3) -Effect of porous assisted DATR on performance index • The total energy loss consisted of sensible heat energy loss carried away by theproducts during the oxidation. The results demonstrated that the energy loss was in the range of 8 to 31 %. • Overall, those reactions with a PM installed in the reaction zone were able to attain a better reforming efficiency and reduced energy loss percentage. This allowed the methane conversion efficiency to improve effectively, increasing the production of hydrogen and carbon monoxide. Relationship between energy loss percentage and reforming efficiency under varying reforming parameters. 8

  11. Conclusions Fire observation From the fire observation and reaction temperature measurement, it could be confirmed that the PM arrangement was helpful to preheat reactant by heat recirculation. It also contributed to the uniformity of gas distribution and thereby to decrease the gradients of temperature and concentration in the reaction chamber. Equilibrium adiabatic temperature With the assistance of PM, the reformate gas temperature of the DATR could be raised, and even higher than the EAT. As a result, it need not provide the external energy to the DATR for self-sustaining reaction; although it is a strongly endothermic reaction. Reforming performance improvement The reforming performance improvement could be achieved on DATR with PM assisting. The improvement in methane conversion efficiency was 18%, reforming efficiency was 33.9%, and energy loss percentage was 20.7% with the best parameter settings (CO2/CH4=1and O2/CH4=0.75) by the OBSiC foam. 9

  12. Thanks for your attention Hydrogen for the future ! Ming-Pin, LaiJet propulsion/Fuel cell Lab. Department of Aeronautics and AstronauticsNational Cheng Kung UniversityNo. 1, University Rd., Tainan City, Taiwan, R.O.C.E-mail: p4896112@mail.ncku.edu.tw

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