Abstract: Processing of wet biomass feedstock by liquid-phase catalytic hydrothermal gasification must address catalyst fouling and poisoning. One solution can involve heating the wet biomass with a heating unit to a pre-treatment temperature sufficient for organic constituents in the feedstock to decompose, for precipitates of inorganic wastes to form, for preheating the wet feedstock in preparation for subsequent removal of soluble sulfate contaminants, or combinations thereof. Processing further includes reacting the soluble sulfate contaminants with cations present in the feedstock material to yield a sulfate-containing precipitate and separating the inorganic precipitates and/or the sulfate-containing precipitates out of the wet feedstock. Having removed much of the inorganic wastes and the sulfate contaminants that can cause poisoning and fouling, the wet biomass feedstock can be exposed to the heterogeneous catalyst for gasification.

Abstract: A tubesheet support arrangement 11 supports a tubesheet 10 within a vessel 12, the tubesheet 10 maintaining a plurality of tubes 22 at fixed radial spacings from one another with the tubes 22 extending from the tubesheet 10 on a tube projecting side of the radial plane RP. The tubesheet support arrangement 11 comprises a fully circumferentially extending intermediary support element 24. The intermediary support element 24 is subjected to compression due its support of the weight of the tubesheet 10 and the tubes 22 on the lower portion of the vessel 12.