Abstract: An apparatus and process for providing purified natural gas wherein a natural gas feed mixture of hydrocarbons, nitrogen, and other permeable gases is provided to a semi-permeable membrane separator having a relatively higher selectivity for methane and other hydrocarbons and a relatively lower selectivity for nitrogen, to thereby provide a gaseous permeate product enriched in hydrocarbons and diminished in nitrogen.

Abstract: An apparatus and method are described for refrigeration employing a condenser, an evaporator, and a compressor, wherein a condenser vent is provided for exhausting accumulated mixtures of non-condensable gas, such as air, and refrigerant gas, wherein accumulated non-condensable gas mixed with refrigerant gas from the condenser vent is provided to a membrane separator comprising at least two chambers separated by a selective membrane, said chambers being a high pressure chamber to which the non-condensable gas mixed with refrigerant gas is supplied, and a low pressure chamber into which the refrigerant gas is selectively permeated through said selective membrane for reintroduction and reuse in the refrigeration cycle, and on said high pressure chamber of said membrane separator, a vent is provided to exhaust non-condensable gas-rich raffinate gas.

Abstract: A membrane process and apparatus are described for the production of a desired very high purity permeate gas by use of a multiple stage membrane process wherein in a primary stage a process feed gas mixture is provided to a primary membrane separator unit comprising a membrane having a relatively high intrinsic permeability to provide an intermediate permeate gas and a retentate gas, and providing the intermediate permeate gas in a secondary stage to a secondary membrane separator unit comprising a membrane having a relatively low intrinsic permeability, to produce therefrom a very high purity permeate gas product.

Abstract: A semi-permeable gas membrane process is described for the separation of very high purity nitrogen from a process feed gas mixture that is predominantly nitrogen, and one or more other permeable gases, which process comprises providing a feed gas mixture under pressure to a membrane separator unit comprising a semi-permeable separation membrane with respect to which the largest fraction of the other permeable gases is at least 20 times more permeable than nitrogen, to provide a very high purity raffinate nitrogen gas product.

Abstract: A membrane process and apparatus are described for the production of a desired very high purity permeate gas by use of a multiple stage membrane process wherein in a primary stage a process feed gas mixture is provided to a primary membrane separator unit comprising a membrane having a relatively high intrinsic permeability to provide an intermediate permeate gas and a retentate gas, and providing the intermediate permeate gas in a secondary stage to a secondary membrane separator unit comprising a membrane having a relatively low intrinsic permeability, to produce therefrom a very high purity permeate gas product.

Abstract: A process for producing liquid carbon dioxide. A process stream which comprises carbon dioxide, balance substantially nitrogen and water, is cooled so that a minor amount of the water is condensed out. The process stream is compressed so that substantially all of the water but trace amounts is condensed out. Next, the process stream is cleaned to remove the trace amounts of water, any long-chain hydrocarbons present and any particulates present. The process stream is then separated into a nitrogen-rich gaseous stream and a carbon dioxide-rich gaseous stream. The carbon dioxide-rich gaseous stream is then compressed and the nitrogen-rich gaseous stream is expanded to produce an expanded nitrogen-rich gaseous stream. The energy of the expanding is used to compress the carbon dioxide-rich gaseous stream. The compressed carbon dioxide-rich gaseous stream is cooled to liquefy the carbon dioxide in the stream and reduce the temperature of the gaseous nitrogen in the stream.