Hydrogen Production in a Reverse-Flow Autothermal Catalytic Microreactor:  From Evidence of Performance Enhancement to Innovative Reactor Design

Kikas, Timo; Bardenshteyn, Ilya; Williamson, Christopher; Ejimofor, Cornelius; Puri, Pushpinder S.; Fedorov, Andrei G.

doi:10.1021/ie030021c

Cited by 20 publications

(34 citation statements)

References 10 publications

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“…4 in less than 1.0 s. Due to the hydrogen conversion profile does not change for most of the simulation time after about 1.0 s, the aforementioned behavior is often referred to as pseudo-steady-state. Compared with the reaction and diffusion processes, the large thermal inertia of the micro-combustor solid structure leads to slow temperature dynamics, and transient response is dominated by the thermal inertia (Kaisare et al, 2005;Kikas et al, 2003).…”

Section: Transient Behaviormentioning

confidence: 99%

Effect of Wall Thermal Conductivity on Hydrogen-Assisted Catalytic Ignition Characteristics of Propane-Air at Micro-Scales in Different Feeding Modes

Chen¹,

Gao²,

Xu³

2015

Frontiers in Heat and Mass Transfer

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Effect of wall thermal conductivity on hydrogen self-ignition and hydrogen-assisted ignition of propane-air mixtures in different feeding modes from ambient cold-start conditions were investigated numerically with chemical kinetic model in Pt/γ-Al2O3 catalytic micro-combustors. For the steady and transient state, effect of wall thermal conductivity on self-ignition characteristics of lean hydrogen-air mixtures was presented, and hydrogenassisted combustion of propane-air mixtures was investigated numerically in the co-feed mode and the sequential feed mode. The computational results indicate the large thermal inertia of the micro-combustor solid structure leads to slow temperature dynamics, and transient response is dominated by the thermal inertia. The heat localization in poorly conducting walls leads to fast ignition and shorter steady state time. In general, the concentration of hydrogen required for propane ignition increased with increasing wall thermal conductivity, decreasing inlet velocity, and decreasing inlet equivalence ratio of propane-air mixtures. In the co-feed mode, the combustion characteristics of hydrogen-assisted propane qualitatively resemble the selectively preheating initial portion of the combustion chamber wall. In the sequential feed mode, the time taken to reach steady state, the hydrogen cut-off time, the propane ignition time and the cumulative propane emissions increased with increasing wall thermal conductivity; the ignition characteristics are similar to partially preheating the initial segment for low and moderate wall thermal conductivity values (0.5 and 20 W/m· K); however, the ignition characteristics are close to completely heating the micro-combustor wall for high wall thermal conductivity values (200 W/m· K).

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Section: Transient Behaviormentioning

confidence: 99%

Effect of Wall Thermal Conductivity on Hydrogen-Assisted Catalytic Ignition Characteristics of Propane-Air at Micro-Scales in Different Feeding Modes

Chen¹,

Gao²,

Xu³

2015

Frontiers in Heat and Mass Transfer

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“…In order to avoid this problem, a reverse-flow reactor system has been suggested. This concept was first reported for the combustion of low calorific gases, and has been extensively studied over the years [4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Several industrial applications of the technique exist, mainly as regenerative thermal oxidation, for the removal of volatile organic compounds and regenerative catalytic oxidation.…”

Section: Introductionmentioning

confidence: 99%

Modelling of a reverse-flow partial oxidation reactor for synthesis gas production from gasifier product gas

Tunå

Svensson

Brandin

2015

JCM

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This is the published version of a paper published in Journal of Computational Methods in Sciences and Engineering.Citation for the original published paper (version of record):Tunå, P., Svensson, H., Brandin, J. (2015) Modelling of a reverse-flow partial oxidation reactor for synthesis gas production from gasifier product gas.. Abstract. Biomass gasification followed by fuel synthesis is one of the alternatives for producing liquid fuels and chemicals from biomass feedstocks. The gas produced by gasification contains CO, H2, H2O, CO2, light hydrocarbons and tars. The light hydrocarbons can account for as much as 50% of the total energy content of the gas, depending on the type of gasifier, operating conditions and feedstock. The gas also contains catalyst poisons such as sulphur, in the form of H2S and COS. This paper presents simulations of a reverse-flow partial-oxidation reformer that converts the light hydrocarbons into more synthesis gas, while achieving efficiencies approaching that of conventional catalytic processes. Variations in parameters such as pressure, amount of oxidant and steam-to-carbon ratio were also investigated. Simulations of the reforming of natural gas were included for comparison. The results show the benefits of using reverse-flow operation with lean gases such as gasifier product gas. Journal of Computational Methods in Sciences and

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“…Kikas et al [4] operated a microstructured autothermal reformer for methane in conventional and reverse flow mode. In the unidirectional flow mode, 70-80% selectivity towards hydrogen could be achieved along with 55-60% conversion at a methane/oxygen ratio between 0.7 and 0.9.…”

Section: Introductionmentioning

confidence: 99%

Micro‐Structured Methane Steam Reformer with Integrated Catalytic Combustor

et al. 2007

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Experimental results of tests using a micro‐structured steam reformer for hydrogen generation from methane in fuel cell systems are reported. A distinctive feature of this work is the integration of a catalytic combustor into the reactor to deliver the necessary heat to the endothermic steam reforming reaction. The tests are performed under static and dynamic load conditions. The reactor is operated autonomously without external heat supply. The best results are obtained by firing the integrated combustor with a mixture of hydrogen and methane in co‐flow with the reforming reaction. Providing carbon dioxide to the combustor feed in order to simulate the situation of anode off‐gas firing has only minor effects on system performance. Under static load conditions up to 2 / min–1 of hydrogen are produced at high methane conversion rates of about 70%. Start‐up tests show that a stable product composition is obtained in less than 20 s after admission of methane to the reformer. Furthermore, the product composition shows only minor variations with throughput and load changes if heating adjustments are done simultaneously. Overall, the reactor proves to be very suitable for operation in fuel cell systems.

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Hydrogen Production in a Reverse-Flow Autothermal Catalytic Microreactor: From Evidence of Performance Enhancement to Innovative Reactor Design

Cited by 20 publications

References 10 publications

Effect of Wall Thermal Conductivity on Hydrogen-Assisted Catalytic Ignition Characteristics of Propane-Air at Micro-Scales in Different Feeding Modes

Effect of Wall Thermal Conductivity on Hydrogen-Assisted Catalytic Ignition Characteristics of Propane-Air at Micro-Scales in Different Feeding Modes

Modelling of a reverse-flow partial oxidation reactor for synthesis gas production from gasifier product gas

Micro‐Structured Methane Steam Reformer with Integrated Catalytic Combustor

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