Reformer microchannel oxidative steam

A second generation system, as shown in Figure 5.61. It was composed of a microchannel oxidative steam reformer, which was supplied with water by a humidifier. The humidifier utilised cathode off-gas for humidification. Steam reforming was performed at a S/C ratio of 1.6 and O/C ratio 0.2. The microchannel steam reformer was coupled to an integrated catalytic burner The burner was... 

An alternative to filling or coating with a catalyst layer the microcharmels, with the related problems of avoiding maldistribution, which leads to a broad residence time distribution (RTD), is to create the microchannels between the void space left from a close packing of parallel filaments or wires. This novel MSR concept has been applied for the oxidative steam reforming of methanol [173]. Thin linear metallic wires, with diameters in the millimeter range, were close packed and introduced into a macro tubular reactor. The catalyst layer was grown on the external surface of these wires by thermal treatment. 

Aartun, 1., Venvik, H.J., Holmen, A., Pfeifer, P Gdrke, O. and Schubert, K. (2005) Temperature profiles and residence time effects during catalytic partial oxidation and oxidative steam reforming of propane in metallic microchannel reactors. Catal. Today, 110 (1-2), 98-107. 

Achieve high efficiency through integration of steam reforming, water gas shift, and preferential oxidation reactors with microchannel recuperative heat exchangers, fuel and water vaporizers, condensers, and separators. 

Fichtner et al. [66] used a monolithic microchannel reactor for partial oxidation of methane. The reaction was carried out at 1000°C temperature, 25 bar pressure and residence times in the order of few milliseconds. The adiabatic hot spot formation was calculated to be 2320° C. This excessive hot spot was expected to be reduced in the metallic honeycomb by axial heat transfer from the oxidation to the steam reforming reaction zones. 

The addition point of gaseous fuels requires careful consideration to avoid homogeneous reactions upstream of the reformer vith autothermal reforming and partial oxidation. Commercial flame arresters are normally not capable of operating under the elevated temperatures of the fuel processor. Microchannels are known to act as flame arresters (see Section 6.3.2) and may be inserted into the tubing system to avoid uncontrolled reaction of the fuel/air mixture. For liquid fuels, which are usually injected into the pre-heated steam feed or even into the air/steam feed mixture, either cooled injection nozzles [567] or the application of steam jackets may be used to ensure stable operation of the nozzle. 

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