The conversion of hydrocarbon fuels, including natural gas, to H2 can be carried out by several reaction processes, including steam reforming (SR), partial oxidation (POX), and autothermal reforming (ATR). Steam reforming is generally the preferred approach to achieve high purity hydrogen, having higher system efficiency in comparison to POX and ATR. Since steam reforming is endothermic, some amount of the fuel must be burned and the heat must be transferred to the reformer via heat exchangers. Thus, effective energy utilization from waste heat and poor quality fuels is of importance to an integrated H2 generation unit for improving the overall system efficiency. Precision Combustion, Inc. (PCI) has been developing a novel heat-integrated steam reforming reactor for efficient syngas (i.e., H2 and CO) generation based on its patented Microlith® technology, providing higher heat flux compared to other state-of-the-art reactors. The Microlith based reactor design results in a remarkably compact, lightweight, and efficient steam reforming reactor, which is otherwise widely known to be limited by the heat transfer resistance from the exothermic (heat source) to the endothermic reforming side. The burner component comprises of catalytic oxidizer instead of flame-stabilized combustion, resulting in improved temperature control and uniformity. In addition to the steam reformer, PCI has also developed an oxygen-blown, natural gas ATR that was designed for producing a syngas stream with a specific hydrogen-to-carbon monoxide ratio. This ATR system was developed and demonstrated to supply syngas with a specific H2-to-CO ratio to meet customer requirements. This system was integrated by an industrial fluid and gas handling firm under PCI’s supervision after performance shakedown and validation performed at PCI’s facility. The system was delivered to the customer, accepted and intermittently used over a period of two years to support its technology development and testing needs. The system was used for a total of 4,000 hours and produced 50,000 Nm3 of syngas.
In this paper, results from testing the steam reformer with a distillate fuel (containing 2-5 ppmw sulfur) and natural gas will be presented, where near equilibrium product distribution was observed. The effect of steam-to-carbon ratio, operating pressure (i.e., up to 10 atm), and thermal inputs on the catalyst performance, fuel conversion and H2 production for the steam reformer will be discussed. The sulfur tolerance studies of the burner catalyst will also be presented. Catalytic sulfur tolerance allows effective utilization of poor quality or waste fuels in the burner, thus significantly improving the overall process efficiency. Results from hundreds of hours of testing of the steam reformer unit showed minimal catalyst degradation, thus providing a measure of the reactor performance under realistic conditions and demonstrating the durability of the reformer. Separately, results from testing the oxygen-blown ATR for converting natural gas to syngas will be presented. The operational specifications and product stream quality will also be highlighted.