Abstract: In a process for the low-temperature fractionation of air by two-stage rectification wherein nitrogen is withdrawn in the gaseous phase from the upper portion of the high-pressure column, warmed, compressed, cooled, liquefied, and recycled into the upper portion of the high-pressure column, the improvement which comprises conducting the liquefying of the nitrogen in heat exchange with evaporating oxygen in the lower portion of the low-pressure column. This process is particularly amenable to the use of LNG as refrigerant where LNG must be vaporized.

Abstract: In a process for the liquefaction of air or of primary components thereof comprising passing liquefied closed-cycle refrigeration medium in indirect heat exchange relationship with said air or primary components thereof, and wherein the refrigeration value of the closed-cycle medium is produced by compressing said medium, partially condensing compressed medium in several indirect heat exchange stages, and wherein condensate from each stage is expanded, reheated, and revaporized in said indirect heat exchange stages counter-currently to the cycle medium being partially condensed, and the revaporized medium is recompressed,The improvement which comprises recovering resultant uncondensed vapor medium from the last serially connected heat exchange stage, engine expanding said vapor and passing resultant expanded vapor in indirect heat exchange relationship with liquefied air or primary components thereof to subcool same, and wherein the cycle medium is a mixture of nitrogen and hydrocarbon whereby only a single c

Abstract: An air-rectification system comprises a two-stage low-temperature separation column of the LINDE-FRANKL type connected to a heat exchanger whereby air is cooled on passage through the heat exchanger and is introduced into the high-pressure stage of the column, oxygen and nitrogen are fed from the high-pressure stage to a low-pressure stage of the column and are separated therein to form low-temperature product oxygen and nitrogen which are warmed by passage separately through the heat exchanger, and a gas stream, representing a heat-balancing stream (balance stream) is drawn from the rectification column and passed through the heat exchanger, in which one of the gas streams between the heat exchanger and the rectification column is subject to low-temperature compression. The compressed gas stream may be the balance gas stream, the incoming air after cooling in the heat exchanger or one of the product gas streams.

Abstract: In a process for the production of a fuel gas by the pressure gasification of carbon-containing fuels with oxygen and steam, wherein the oxygen is manufactured in a low temperature air separation plant and the steam is formed in a gas-heated steam boiler, and the waste gases produced in the steam boiler are subsequently expanded in an expansion turbine, the improvement which comprises admixing the nitrogen produced during the air separation with the waste gases before the expansion of the latter.