Superadiabatic Partial Oxidation for Hydrogen Production from Hydrogen Sulfide: Process Options and Economics

摘要

There are significant quantities of acid gases (> 200,000 tons/day of H2S processing capacity worldwide), generated mainly as undesirable by-products of fossil fuel processing, including natural gas sweetening, petroleum refining, and coal gasification. Such gases are typically treated with the Claus Process, which is capable of recovering sulfur to the extent required by stringent environmental regulations. The hydrogen component of H2S, however, is wasted as water in this process. In recent years, many approaches have been investigated to recover hydrogen, in addition to sulfur, from H2S. Despite the advances made, no method of H2S decomposition can be considered commercially feasible today. GTI has been developing a novel thermochemical conversion process, based on the superadiabatic partial oxidation concept, to recover a significant portion of the H2 in H2S, while still efficiently recovering sulfur. GTI’s process consists of several components, including the superadiabatic POX reactor, sulfur recovery equipment, and product/byproduct separation membranes to isolate the “unconverted” H2S for recycle, the product H2 for purification, and the tail gas for cleanup. With funding from the U.S. Department of Energy, GTI, and UIC, work has been focused on the superadiabatic reactor. A detailed numerical model has been developed to evaluate the effects of key process parameters on exit gas product yields. A bench-scale reactor system has been designed, constructed, and operated to demonstrate the technical feasibility of the superadiabatic POX concept and to address the effect of key variables on process performance. Results obtained in the experimental program have been very encouraging. In this paper an assessment is made of various options as well as the economic potential for the superadiabatic POX process to produce H2 (and elemental sulfur) from H2S in H2S-rich acid gases. A preliminary estimate for the supply cost of hydrogen via the superadiabatic POX process is developed, by evaluating the economic potential of four selected process schemes. The selected configurations consider the superadiabatic POX process as a stand-alone process as well as in association with additional commercially available sulfur recovery and tail gas cleanup units (I.e., as a retrofit to the Claus Process). All four schemes are compared to natural gas-fired thermal dissociation of H2S and steam methane reforming, the industry standard for large-scale H2 production.