Heat Exchange Reformers, a recent commercial technology, are a ‘scaling down' of tubular steam reformers used for hydrogen production in refineries. A common design element of Heat Exchange Reformers is the bayonet tube. The tube is closed at one end and has an interior wall that divides it into a central tube and an annulus. Typically, the feed enters the central tube and exits via the annulus. Usually a catalyst, in the form of a conventional pellet, is placed in the tubes of the reformer and a hot gas (i.e. from a combustor) or other process effluent is circulated external to the bayonet tube to provide the heat of reaction.

Heat Exchange Reformers have been able to achieve a high thermal efficiency and are compact unit both in volume and mass.

The objective of this investigation is to examine the suitability of the Heat Exchange Reformer technology for the production of hydrogen by methanol steam reforming. The targeted application is an auxiliary power unit that requires about 3 - 4 kWe maximum sustained power. The steam reforming of methanol is used as a test system since there are well validated kinetics and trusted correlations for heat transfer in cylindrical geometries.

The investigation examines the influence of the reformer geometry (inner & outer diameter and length) upon reformer performance using the standard metrics of productivity, conversion and selectivity. A further consideration in the design is the generation of a reformate composition and temperature that is beneficial for the operation of a PrOX reactor, required to reduce carbon monoxide concentrations to levels acceptable for a PEM fuel cell.