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Uc Sulfur Recovery Process – An Integrated Multi-Contaminant Removal Process

Diana Matonis1, Howard Meyer1, Dennis Leppin1, and Scott Lynn2. (1) Gas Technology Institute, 1700 S. Mt Prospect Rd, Des Plaines, IL 60018-1804, (2) University of California Berkeley, Berkeley, CA 94720

The University of California Sulfur Recovery Process (here after referred to as UCSRP-HP) testing addresses the development of an integrated multi-contaminant removal process in which H2S, NH3, HCl and heavy metals including Hg, As, Se and Cd present in a coal-derived syngas are to be removed to parts-per-million (ppm) or in some cases parts-per-billion (ppb) levels in a single process step. H2S is converted directly into elemental sulfur at 275oF to 300oF and at the given sour gas pressure by reaction with sulfur dioxide in the liquid phase. Prior to this, the other contaminates such as NH3, HCl and trace contaminants are removed in a separate section of the same reactor column.  This is accomplished by the solvent absorbing H2S, NH3, HCl  and trace metals from the feed gas.  NH3 and HCl form a highly soluble NH4Cl salt and the absorbed heavy metals As, Cd and Hg precipitate out as their very insoluble sulfides. The Se trace metal, present in the syngas as H2Se, forms a highly soluble (NH4)2Se under these conditions and remains in the solvent.  The proposed process is tightly integrated and is expected to be significantly more economical both in terms of capital and operating costs because it replaces the sulfur removal processes, acid-gas removal, Claus and SCOT, as well as the trace components used or proposed in conventional schemes by one single unit.

This paper will include an  (i) investigation of long-term (i.e., 1000 hrs) solvent stability by exposure of the solvent to a simulated Illinois coal #6 gas containing all the contaminants that may be present in the feed to UCSRP reactor, (ii) investigation of metal corrosion related issues for selecting suitable material of construction for UCSRP reactor, (iii)  investigation of the removal of the trace metal components from the syngas by the selected solvent, (iv) development of an Aspen-Plus based computer simulation model, and (v) techno-economic evaluation of the process applied to syngas cleanup.