Development of a stand alone steam methane reformer for on site hydrogen production
Abstract A small, stationary reformer designed as a stand alone and self sustaining type was developed for on site hydrogen (H2) production. We created a compact reformer to produce H2 at a rate of 1 Nm3/h using the previously reported reaction kinetics of steam methane reforming (SMR) Both catalysts for the compact reformer i.e. 15 wt% and 20 wt% Ni/g Al2O3 showed good activity, with CH4 conversion exceeding 90% at 655 degC and a contact time of 3.0 gcath/mol, which were considered critical thresholds in the development of a small, compact stationary reformer. At an H2 production rate of 1 Nm3/h, the catalyst amount was calculated to be 167.8 g and the reformer length required to charge the catalyst was 613 mm, with a diameter of 1 inch. The CH4 conversion and H2 production rates achieved with the compact reformer using the 20 wt% Ni/g Al2O3 catalyst at 738 degC were 97.9% and 1.22 Nm3/h, respectively. Furthermore, a heat exchanger type reformer was developed to efficiently carry out the highly endothermic SMR reaction for on site H2 production. This reformer comprised a tube side (in which the catalysts were charged and the SMR reaction took place by feeding the reactants) and a shell side (in which the heat for the endothermic reaction was supplied by CH4 combustion) Reforming activities were evaluated using the active 20 wt% Ni/g Al2O3 catalyst, depending on the reactants' gas hourly space velocity (GHSV) The H2 production rate increased as the GHSV increased. Finally, the reformer produced a CH4 conversion of 98.0% and an H2 production rate of 1.97 Nm3/h at 745 degC, as well as a high reactants' GHSV of 10,000 h 1. Therefore, the heat exchanger type reformer proved to be an effective system for conducting the highly endothermic SMR reaction with a high reactants' GHSV to yield a high rate of H2 production.