Abstract: A fluid material is cooled through a temperature range exceeding 200.degree. F. by heat exchange with a single mixed refrigerant composition in a heat exchange zone forming a part of a closed loop refrigeration cycle thus assuring high reliability and low investment by virtue of simplification of the equipment required and ease of control thereof. The process is especially useful for liquefaction of natural gas. Refrigerant in the refrigeration loop containing constituents having increasingly lower boiling points is successively directed from a compression zone to a condensation zone, thence to a heat exchange zone, next expanded in an expansion zone, returned to the heat exchange zone for countercurrent flow against the refrigerant flowing therethrough from the condensation zone to the expansion zone, and finally returned to the compression zone.

Abstract: A commercially feasible method is provided for controlling depositions of solid sulfur within plant equipment utilized in absorptive-regenerative processes for the removal of H.sub.2 S from sour gas streams which eliminates costly shutdowns and manual cleaning of the plant equipment and permits removal of solid sulfur therefrom in conjunction with that produced during the regular process itself. The method comprises adding ammonia to such H.sub.2 S removal systems during running thereof in order to solubilize any solid sulfur and remove the same with the sulfur produced by circulating alkali absorption solution employed. Ammonia may be added to either the sour gas stream or directly to the absorption solution, and moreover can be added intermittently to remove preexisting sulfur deposits or on a semi-continuous basis as needed to substantially prevent undesirable sulfur buildup. The present method finds application in connection with known desulfurization processes such as the Stretford, Ferrox and Takahax.