Characteristics of excess enthalpy on dry Characteristics of excess enthalpy on dry autothermal reforming from simulated biogas autothermal reforming from simulated biogas

with porous mediawith porous media

M.P. Lai, W.H. Lai, C.Y. Chen, S.S. Su, R.F. Horng,

W.C. Chiu, Y.M. ChangDepartment 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)

M.P. Lai, W.H. Lai, C.Y. Chen, S.S. Su, R.F. Horng,

W.C. Chiu, Y.M. ChangDepartment 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)

Reporter : Ming-Pin LaiReporter : Ming-Pin Lai

Date : 2012/06/05Date : 2012/06/05

Reforming & Gasification, Biomass-1, HPB6

ConclusionsConclusions

EquipmentEquipment details and parameters design details and parameters design

Related literature and objectiveRelated literature and objective

Contents

Introduction and motivationIntroduction and motivation

Preliminary achievementPreliminary achievement Effect of excess enthalpy on reaction gas temperature Effect of porous assisted DATR on performance index

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 flue gas and exhaust gasexhaust gas are attractive as waste heat for endothermic reaction.

Advantage:Advantage:Heating value

H2-rich gas for power system (ICE/GT/*FC…etc)Assisting combustion (Incinerator)

Syngas applicationSynthesis fuel (Diesel, Gasoline, JP, DME, MeOH)

GHG reductionMitigation, Recycle, Reuse

Biogas

Landfill

Biomass

Introduction and Motivation

CO2 mitigation and H2 generation

1

Reforming (Thermal-chemical)Reforming (Thermal-chemical) COCO22 decomposition : decomposition : COCO22→CO+0.5O→CO+0.5O22

Gasification (Boudouard) : C+Gasification (Boudouard) : C+COCO22→2CO→2CO

COCO22 reforming of CH reforming of CH4 4 : CH: CH44++COCO22 →2CO+2H →2CO+2H22

Reverse water gas shifting : Reverse water gas shifting : COCO22+H+H22 →CO+H →CO+H22OO

COCO2 2 -Methanation : -Methanation : COCO22+4H+4H22 →CH →CH44+2H+2H22OO

Reduction (Photo-chemical)Reduction (Photo-chemical)

SynthesisSynthesis

Reference Gas sourceCompositions (Vol. %)

CH4 CO2 N2 CO H2 H2S O2 NH3

Ryckebosch Biogas gas 40-75 15-60 0-2 <0.6 - 0-2 0-1 <1Speight Biogas gas 50-75 25-50 0-10 - 0-1 0-3 0-2 -Persson Biogas gas 53-70 30-47 0-1 - 0 0-1 0 -Deublein Biogas gas 45-75 25-55 0-5 0-0.2 0.5 0-1 0-2 -

Lai Simulated gas 50-75 0-50 - - - - - -

Composition of biomass derived gas.

Related Literature and objective(1/2)

Comparison of the Tead and TR under varying reforming parametersComparison of the Tead and TR under varying reforming parameters

2WH 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.

( ) 100%

fuel

abs HEnergy loss rate

LHV

The figure shows a schematic diagram of the temperature histories of premixed combustion both without and with heat recirculation

Excess enthalpy (Super-adiabatic temperature)Excess enthalpy (Super-adiabatic temperature)

Related Literature and objective(2/2)

3

The internal heat recirculation mechanism by heat transfer. Modified after [8]

Schematic of experimental arrangement

Experimental details

4

Reforming parameters:Fuel feeding rate : 10 L/min-CH4

CO2/CH4 : 0, 0.33, 1O2/CH4 : 0.5, 0.75, 1.0Reforming mode : POX, DATR

Porous media specifications :Material: OBSiC, Al2O3, ZrO2, Cordierite, Fe-Cr-Al alloyStructure: 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

Experimental parameter design

BET

Surface

Area

(m2/g)

BJH

desorption

Pore Size

(nm)

t-Plot

Micropore

Volume

(cm3/g)

Langmuir

Surface

Area

(m2/g)

139.5315 18.58724 0.002999 192.4729

Relationship of O2/CH4 molar ratio and reaction of

enthalpy under methane reforming

Relationship of O2/CH4 molar ratio and reaction of

enthalpy under methane reforming

5

Preliminary achievement (1/3)-Photographic observation on PM assisted DATR

6

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.

Comparison of the equilibrium adiabatic temperature and reformate gas temperature with or without PM assisting under varying reforming parameters

Preliminary achievement (2/3)-Effect of excess enthalpy on reaction gas temperature

7

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

Relationship between energy loss percentage and reforming efficiency under varying reforming parameters.

Relationship between energy loss percentage and reforming efficiency under varying reforming parameters. 8

100%2 2H H CO CO

reformingSimulated fuel Simulated fuel

m LHV + m LHV

m LHV

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.

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.

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.

Conclusions

Fire observation

Equilibrium adiabatic temperature

9

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.

Reforming performance improvement

Ming-Pin, LaiJet propulsion/Fuel cell Lab.

Department of Aeronautics and AstronauticsNational Cheng Kung University

No. 1, University Rd., Tainan City, Taiwan, R.O.C.E-mail: p4896112@mail.ncku.edu.tw

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