Abstract: There is provided a slagging coal combustion system suitable for retrofitting boilers, furnaces and industrial-process heat generators originally designed to burn oil or gas. It comprises a primary combustion chamber into which oxidizer and fuel are injected to provide high-velocity, rotational-flow combustion zones, such that the fuel is burned substoichiometrically, while in flight, with up to 90% of the resultant ash being removed as molten ash. The combustion products pass from the primary chamber to chamber where slag is removed and the gaseous products are passed to end-use equipment. A coal-fired precombustor subsystem feeds partially-heated air as the oxidizer to the primary combustion chamber supply of oxidizer, at any selected temperature within the range from about 1200.degree. F. to about 2000.degree. F. The stoichiometry of this precombustor and the velocity and mass-flow rates of its output stream are independently controllable.

Abstract: In a combustion zone a fuel injector is immersed in a mixture of oxidant and products of combustion having a temperature of about 2000 degrees F. or higher. In order to maintain rapid and stable combustion, it is desirable to avoid excessive absorption of thermal energy from this mixture. To that end, the present invention provides means for impeding transfer of heat to the fuel injector from the adjacent mixture, such that portions of the mixture immediately adjacent the fuel injector may be kept at a temperature of approximately the ash-fusion temperature of the fuel, or higher, while the interior of the fuel injector is kept at a temperature substantially below the ash-fusion temperature. This means for impeding heat transfer preferably comprises at least one material having a thermal conductivity substantially lower than that of the fuel injector and, in a preferred embodiment, consists essentially of slag formed from noncombustible-mineral constituents of the fuel.

Abstract: Alkali metal hydroxide solutions are purified and concentrated by electrolysis of such solutions in a hybrid cell comprising an anode compartment and a central compartment separated from the anode compartment by a cation permeable diffusion barrier, and a cathode compartment in flow communication with the central compartment and separated from the central compartment by a diaphragm. To enable operation, gaseous hydrogen is supplied to the anode, oxygen to the cathode, an aqueous solution of at least one alkali metal hydroxide to the anode compartment, and an aqueous media receptive to alkali metal ions to the central compartment. A plurality of the hybrid cells may be operated in hydrodynamic series.

Abstract: Hydrofluoric acid is recovered from fluosilicic acid by reacting fluosilicic acid with sodium sulfate to form sodium fluosilicate. The sodium fluosilicate is reacted with a sodium-containing compound to form an alkaline aqueous slurry comprising silica and dissolved sodium fluoride. The reaction occurs under such conditions that the slurry contains precipitated amorphous silica. The precipitated amorphous silica is separated from the alkaline aqueous slurry leaving an aqueous solution of sodium fluoride. Sodium fluoride is recovered from the aqueous solution and reacted with sulfuric acid to produce hydrogen fluoride.

Abstract: Finely divided, sulfur bearing carbonaceous materials are carried by hydrogen in counter-current flow at elevated temperatures to the flow of relatively large, metal oxide, hydrogen sulfide accepting pellets. The sulfur contained in the carbonaceous material reacts with the carrier hydrogen to form hydrogen sulfide which, in turn, reacts with the metal oxide to form the corresponding metal sulfide and water. The water and unreacted carrier hydrogen are then separated from the desulfurized carbonaceous material and following separation of water from the residual hydrogen, the hydrogen is recycled with make up hydrogen at elevated pressures to the desulfurization zone. The formed metal sulfide pellets are removed from the base of the desulfurization zone and oxidized back to the oxide state for recycle back to the opposed end of the desulfurization zone.