Reporter : Ming-Pin Lai 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

Contents Conclusions 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

Introduction and Motivation CO2 mitigation and H2 generation CO2 is a valuable carbon source. The low carbon economy through chemical recycling of CO2 with 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 Reference Gas source Compositions (Vol. %) CH4 CO2 N2 CO H2 H2S O2 NH3 Ryckebosch Biogas gas 40-75 15-60 0-2 <0.6 - 0-1 <1 Speight 50-75 25-50 0-10 0-3 Persson 53-70 30-47 Deublein 45-75 25-55 0-5 0-0.2 0.5 Lai Simulated gas 0-50 Biogas Landfill 1. Amorphous flakes and filamentous carbon : CO decomposition. 2. Encapsulating carbon : decomposition of HC. 3. Pyrolytic carbon : Thermal cracking of hydrocarbons. 4. Soot formation : Substoichiometric methane oxidation. 二氧化碳減量方式 1. 提高能源使用效率 2. 使用低碳燃料與新興及再生能源 二氧化碳回收之規劃 1.低溫冷凝(Cryogenic Separation) 2.物理吸附(Physical Adsorption) 3.薄膜分離(Membrane Separation) 4.化學吸收(Chemical Absorption) 二氧化碳回收之封存技術 1.海洋封存 2.地底封存 3.生物封存 4.礦物碳酸化封存 二氧化碳再利用技術 1.超臨界流體 2.光化學法轉換 3.合成高分子聚合物 國際上CO2重組相關研究： CO2/CH4 重組 RWGS (H2+CO2 →H2O+CO) Flue gas recycle(NH3/CO2) C+CO2 →2CO MeOH synthesis Pressure swing absorption, PSA Plasma assisted Exhaust gas recirculation, EGR 天然氣水合物是由水分子組成的冰晶結構空隙中包含天然氣分子，為一種籠形包合物。當天然氣由固態水合物中分解或熔解出來時，一立方公尺的天然氣水合物，在標準狀態的溫度及壓力下，可產生大約 0.8 立方公尺的水，及大約 170 立方公尺的天然氣，所解離出來的水及天然氣，會隨著天然氣水合物組成的不同，而有些微的差異。 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

Comparison of the Tead and TR under varying reforming parameters 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

Excess enthalpy (Super-adiabatic temperature) 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

Schematic of experimental arrangement Experimental details Schematic of experimental arrangement 4

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 (100 cell/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 BET Surface Area (m2/g) BJH desorption Pore Size (nm) t-Plot Micropore Volume (cm3/g) Langmuir 139.5315 18.58724 0.002999 192.4729 5

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

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

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 the products 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

Conclusions Fire observation Equilibrium adiabatic temperature 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

Thanks for your attention Hydrogen for the future ! Ming-Pin, Lai Jet propulsion/Fuel cell Lab. Department of Aeronautics and Astronautics National Cheng Kung University No. 1, University Rd., Tainan City, Taiwan, R.O.C. E-mail: p4896112@mail.ncku.edu.tw