Development of highly efficient hot-gas cleanup technology for advanced IGCC system involving coproduction of hydrogen and liquid fuels

Development studies of hot-gas cleanup system, especially highly efficient desulfurization technologies have been carried out in order to realize the highly effective coal gasification power plants such as IGCC and related systems involving coproduction of hydrogen and/or liquid fuels (GTL or CTL). In continuing our studies of zinc ferrite and related compounds as desulfurization agents, we have found several excellent sorbent systems for hot reductive gases such as coal gas produced by an entrained-flow gasifier. The performance tests of the sorbent systems were carried out at a fixed-bed type bench-scale reactor at 250-600°C under atmospheric and pressurized conditions, using simple reductive gas containing hydrogen sulfide and/or related gas. Some sorbent systems composed of zinc ferrite and metal oxides and/or metal sulfides were found to show excellent desulfurization performance for some representative sulfur compounds; concentrations of hydrogen sulfide, dimethyl sulfide, and thiophene involved in the reductive gases were respectively decreased to less than 50 ppbv; the performance of the desulfurization agents for synthesis gas is satisfactory with respect to production of high grade hydrogen and/or liquid fuels such as methanol and DME. The regeneration of the sorbent systems after sulfidation is carried out by oxidation. The feature of breakthrough curves for the sulfuric gases suggests that deactivation of the sorbent systems during absorption-regeneration cycles is negligible. The characteristics of zinc ferrite and related systems will be discussed in relation with sorbent systems for hot-gas cleanup process of IGCC power generation system involving coproduction of hydrogen and/or liquid fuels; the coproduction process is integrated with IGCC system in parallel with the combined cycle of gas turbine and steam turbine.