Abstract: An apparatus for simultaneously producing both high and low purity oxygen, which contains a double rectification column having therein a lower pressure fractionating column with two reboilers therein, and a higher pressure fractionating column, wherein an intermediate outlet is provided between the two reboilers of the lower pressure fractionating column for extracting a lower purity oxygen stream therefrom, and a high purity liquid oxygen stream from a bottom portion of the column simultaneously.

Abstract: A method of and apparatus for separating C.sub.4 hydrocarbons from a feed comprising a gaseous mixture. The feed is cooled and partially condensed in a plurality of successive stages of condensation and phase separation. A gaseous overhead from each separation stage is further cooled and supplied to the next separation stage and the liquid separated from each stage is used to cool the gas. Further refrigeration is supplied to the gas to effect the condensations by indirect heat exchange with a closed cycle refrigerant subjected to a compression/expansion cycle. The feed undergoes no compression and no abrupt expansion during the separation, so that the feed undergoes a pressure decrease due only to friction of the passage of the feed through the apparatus. The pressure loss is no more than about 20 psi. The temperature of the feed is maintained below 150.degree. F. at all times, to prevent polymerization of 1,3-butadiene.

Abstract: A process for producing gaseous nitrogen from a mixture to be treated in a distillation column, said mixture comprising nitrogen and oxygen, said process comprising the steps of:a) compressing the mixture to be treated to a pressure at least equal to the column pressure;b) cooling the compressed gas mixture and subjecting at least a first portion of said cooled mixture to expansion through a turbine to produce the required refrigeration and thereafter fractionated distillation in the column to obtain at the bottom of the column, an oxygen-enriched fraction and, at the top of the column, a nitrogen-enriched fraction,c) drawing off at least a portion of the nitrogen-enriched fraction as nitrogen product;d) compressing the remaining portion of the nitrogen-enriched fraction;e) recycling at least a portion of the compressed remaining portion of the nitrogen-enriched fraction to the bottom reboiler of the column where it condenses to provide reboil for the column;f) introducing at least a portion of the condensed

Abstract: A process for simultaneously providing both high and low purity oxygen from a double column, double reboiler apparatus, the double columns being high and low pressure columns, the low pressure column having a lower and upper reboiler with an intermediate outlet in between, which process entails extracting a low purity oxygen stream at the intermediate outlet and a high purity liquid oxygen stream from a bottom portion of the low pressure column.

Abstract: A method of liquefying a low-boiling gas, in which gas is compressed to a high pressure, is cooled in heat exchange structure and is isenthalpically expanded to condense a portion of the same to liquid. The liquid being separated from residual gas and the residual gas is used to cool the heat exchange structure and is then recycled. A portion of the gas is compressed to an intermediate pressure between the high and low pressures, is isentropically expanded at a first temperature and is used to cool a relatively warm portion of heat exchange structure and is then recycled. A portion of the high pressure gas is isentropically expanded at a second temperature and used to cool a relatively cool portion of the heat exchange structure and then again isentropically expanded at a third temperature to that low pressure and returned through the heat exchange structure to cool the same and is then recycled.

Abstract: A cryogenic distillation process for the production of oxygen and nitrogen is provided, which entails:a) providing a feed stream of clean, dry and compressed air,b) cooling at least a fraction of the compressed air and introducing the same into a high pressure column, and separating the same into nitrogen-rich stream at the top of the column and an oxygen-rich stream at the bottom of the column, wherein the overhead of the high pressure column exchanges heat with both the bottom of the low pressure column and the bottom of an intermediate column,c) introducing at least a fraction of the oxygen-rich stream into the intermediate column to afford a top liquid fraction A and a bottom liquid fraction B, the overhead of the intermediate column exchanging heat with the low pressure column at a location above the bottom reboiler of the low pressure column, wherein the pressure of the intermediate column is lower than the high pressure column but higher than the low pressure column,d) introducing at least a fraction o

Abstract: A process of producing nitrogen by cryogenic separation of air in a single distillation column process, in which cooled feed air is passed to a reboiler heat exchanger in a distillation column, whereby in the column a portion of a formed nitrogen-rich stream is used for reflux, and the remaining portion is recovered as vapor and liquid product, and a portion of a formed oxygen-rich stream is used for reflux, and a remaining portion is recovered as product, and wherein the nitrogen-rich stream is used to provide process refrigeration.