Air Products and Chemicals, Inc.

Thomas E Cormier, Sr

Rakesh Agrawal

Donald W Woodward

Alan L Prentice

Keith B Wilson

Bruce Kyle Dawson

William J McAuley

Thomas C Young

The present invention relates to a process for the liquefaction of a nitrogen stream produced by separating air components, by using the combination of cryogenic distillation with improved refrigeration. Very cold liquefied natural gas (LNG) is employed as refrigerant, with the LNG currently being revaporized for transportation. Multi-stage component compression is used, with the component feed to each compression stage being precooled using sequential refrigeration from the LNG. Expander means for the coldest air component product stream provides supplemental refrigeration at the cold end beyond that which is available from the refrigerant LNG. In a preferred embodiment, the feed nitrogen stream(s) are compressed to at least 300 psi in a multi-stage compressor with interstage cooling provided by heat exchange against vaporizing LNG; the resulting compressed stream is directed into first and second nitrogen substreams, followed by further cooling of the first substream by heat exchange against vaporizing LNG and then expanding the cooled first substream to produce an expanded nitrogen substream. Condensing of the second compressed substream against both vaporizing LNG and the expanded nitrogen substream is carried out. Reducing the pressure of the condensed second nitrogen substream produces a two phase nitrogen stream. Phase separation yields a recyclable nitrogen vapor stream and a liquid nitrogen stream as product.

Use of liquefied natural gas (LNG) coupled with a cold expander to

The present invention relates to an improvement for the production of ultra-high purity oxygen from cryogenic air separation processes which produce nitrogen and/or commercial purity oxygen products. In particular, the improvement comprises removing or producing an oxygen-containing but heavy contaminant-lean (free, stream from one of the distillation columns of a single or multiple column cryogenic air separation facility and further stripping the removed or produced oxygen-containing stream in a fractionator to produce ultra-high purity oxygen (i.e., contaminant concentration &lt;10 vppm).

Production of ultra-high purity oxygen from cryogenic air separation

A process is set forth for the separation of air by cryogenic distillation in a single column to produce a nitrogen product and an oxygen-enriched product. In the process, at least a portion of the nitrogen product is compressed and recycled to provide reboil at the bottom of the distillation column and to provide some additional reflux to the upper portion of the column. In addition, part of the compressed nitrogen recycle stream is expanded to provide work.

Air separation process

A process is set forth for the separation of air by cryogenic distillation in a single column to produce a nitrogen product and an oxygen-enriched product. In the process, at least a portion of the nitrogen product is compressed and recycled to provide reboil at the bottom of the distillation column and to provide some additional reflux to the upper portion of the column. In addition, part of the compressed feed air stream is expanded to provide work, which is used to drive an auxiliary compressor for feed air substream compression.

Process for the separation of air

A process is set forth for the separation of air by cryogenic distillation in a single column to produce a nitrogen product and an oxygen-enriched product. In the process, at least a portion of the nitrogen product is compressed and recycled to provide reboil at the bottom of the distillation column and to provide some additional reflux to the upper portion of the column. In addition, part of the compressed air stream is expanded to provide work, which is used to drive an auxiliary compressor for recycle nitrogen stream compression.

A method of oxygen recycle on the bottom section of the low-pressure column of a dual-pressure column, with an increase in the bottom section reboil vapor rate, allows an appreciable increase in the production rate of ultra high purity oxygen and a substantial decrease in power required as compared to conventional processes.

Process for producing ultra high purity oxygen

A cryogenic air separation system is described in which pressure-swing adsorption driers are used to remove virtually all of the moisture from the feed air prior to the passage of the feed air stream through reversing heat exchangers which remove the carbon dioxide. The reversing heat exchangers are regenerated by at least one outgoing product nitrogen stream, while the adsorption driers are regenerated by all or a portion of a low pressure stream withdrawn from the low pressure column the composition of which may be rich in either nitrogen or oxygen depending upon whether the volume of product nitrogen or oxygen is to be maximized. A portion of this low pressure stream may be recovered as a dry product stream, while an additional stream of high purity product oxygen may also be recovered.

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Allentown, PA, United States of America

Thomas E Cormier, Sr