Current industrial-scale steam reformers are capable of high efficiencies, however they are not economical for small-scale capacity (<500kW or 0.1MM SCFD hydrogen production) or suitable for isolated operation �i.e. absence of pre-existing utility infrastructure. Process technologies for small-scale, distributed reforming of natural gas must be self-sustaining �if used in isolated or mobile locations, compact and easy to transport, assemble, and relocate, all while retaining competitive system efficiencies. Power & Energy, Inc. has developed a novel annular micro-channel reactor (AMR) consisting of an inner open-ended tube nested within an outer close-ended tube, such that the annular space acts as a radial microchannel. This design effectively combines the advantages of micro-channel reactors (specifically, order-of-magnitude improvements in available heat transfer surface area per unit process volume) with those of traditional large annular reactors (specifically in-situ preheating of feed and greater control over reaction temperature uniformity), while providing additional advantages in operation and manufacturability over existing micro-channel planar designs. This presentation will detail a combination of experimental and theoretical analysis of the AMR prototype design for the endothermic steam reforming of methane to hydrogen. Experiments were performed using a 3.3:1 steam-to-methane supply to a bench-scale AMR operated at 750oC and 11 bar, with continuous measurement of effluent hydrogen partial pressure.  Comparison of experimental data with a two-dimensional computational fluid dynamic (CFD) model provided a validation of model expressions. The validated CFD model was employed to predict performance of a final production AMR design, including individual micro-channel reactor heat duties, effluent compositions, and potential for local catalyst deactivation.

Annular micro-channel reactors: Compact and efficient CH4-steam reformers used to produce H2

248th National Meeting (2014)

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