Economics of thermal dissociation of H 2S to produce hydrogen

Abstract

Two process schemes for the thermal decomposition of H 2S were studied and their economics evaluated. The first scheme involved the recycling of H 2S through a modified steam methane reforming type furnace so that all of the possible hydrogen could be extracted. In the second scheme, H 2S was passed once-through a decomposition/heat exchanger type reactor then on to a conventional Claus sulphur recovery plant. A model incorporating the influence of heat transfer on the thermal decomposition predicted H 2S conversions from 22 to 26%. The cost of producing hydrogen is significantly greater for the second scheme because only 22% of the available hydrogen is recovered. The cost of producing hydrogen using the first scheme is greater than that from conventional steam methane reforming, but with improvements in heat transfer and separations the process should become more competitive.