The Boc Group, Inc.

Timothy D Atkinson

John T Lavin

David T Linnett

An incoming stream of gas mixture typically comprising methane and up to 12% by volume of carbon dioxide is subjected to rectification in a first column to form a carbon dioxide depleted fraction that is withdrawn as product from the top of the column and a carbon dioxide-enriched fraction which is withdrawn from the bottom of the column is warmed in a heat exchanger and is introduced into a second rectification column operating at a higher pressure than the first column. A stream in which carbon dioxide predominates is withdrawn from the bottom of the higher pressure column while a stream 34 containing a lower proportion of carbon dioxide than said enriched fraction is withdrawn from the top of the higher pressure column is throttled through a valve and is united with the incoming stream of gas mixture upstream of or in the lower pressure column.

Separation of gaseous mixtures

In a process for the separation of argon from air by distillation in a plurality of distillation columns, liquid oxygen and gaseous nitrogen, withdrawn from a distillation column, are introduced into opposing ends of a mixing zone and there are created opposing flows of liquid and vapor that become progressively richer in nitrogen and oxygen, in the direction of flow. A mixed stream containing both oxygen and nitrogen is withdrawn as waste or product from an intermediate point in the mixing zone. The mixing zone also provides for condensation and reintroduction of oxygen-rich vapor and return of liquid nitrogen to the distillation column. The distillation column further provides an intermediate condenser which provides intermediate reboil for the distillation column.

Air separation

In a method and apparatus for separating air a distillation zone is employed to separate air into an oxygen-enriched liquid fraction and a nitrogen-enriched vapor-fraction. A first stream is taken from the nitrogen-enriched vapor fraction and is mixed with a stream taken from the oxygen-enriched liquid fraction. At least part of the resultant mixture is employed to perform a refrigeration duty, for example the condensation of nitrogen-enriched vapor to provide reflux for the distillation column.

Air separation method and apparatus

In a process for the separation of argon from a gaseous mixture comprising argon, nitrogen and oxygen by fractional distillation in a plurality of distillation zones, first and second fluid streams comprising nitrogen and oxygen, respectively, drawn from the same or different distillation zones, are introduced into different regions of a liquid-vapor contact and mixing zone. There is established in the contact and mixing zone a liquid flow that becomes progressively richer in nitrogen and a vapor flow that becomes progressively richer in oxygen. A mixed waste stream containing both oxygen and nitrogen is withdrawn from an intermediate point in the contact and mixing zone thereby enhancing its efficiency. Vaporous oxygen from the warmer end of the contact and mixing zone is condensed and returned to the mixing zone to enhance its reflux and/or may be passed into a distillation zone. The fluid in the contact and mixing zone may be utilized therein or in the distillation zone for heating or refrigeration through heat transfer.

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London, United Kingdom

Timothy D Atkinson