Abstract: A method for producing mechanical energy from geothermal fluids in which a heat transfer fluid (HTF) is heated by direct contact with the hot geothermal fluids, thereby partially cooling the geothermal fluids. A working fluid is heated by direct contact with the partially cooled geothermal fluid and is heated further by indirect heat exchange with the hot HTF. The heated working fluid is utilized in a heat engine for the production of mechanical energy.

Abstract: A method for producing mechanical energy from geothermal brine in which a heat transfer fluid (HTF) is heated by direct contact with the hot geothermal brine in cocurrent flow through a series of flash stages which are maintained at successively lower pressures so that the HTF is vaporized in each stage. A working fluid is countercurrently flowed through the series of flash stages in indirect heat exchange with the vapor produced in each stage so that the vapor is condensed in each stage and the working fluid is progressively heated as it passes through the series of flash stages. The heated working fluid is utilized in a heat engine for the production of mechanical energy.

Abstract: A process for the conversion of H.sub.2 S to SO.sub.2 in a feed gas containing H.sub.2 S is effected by oxidation with air or oxygen at temperatures between 300.degree. and 900.degree. F. The oxidation is conducted in the presence of an extremely stable oxidation catalyst comprising an oxide and/or sulfide of vanadium supported on a non-alkaline porous refractory oxide. The preferred catalyst comprises between 5 and 15 wt.% V.sub.2 O.sub.5 on hydrogen mordenite or alumina. Hydrogen, carbon monoxide and light hydrocarbons present in the feed gas are not oxidized. The invention is especially contemplated for use in treating waste gases from geothermal steam power plants.