Air Products and Chemicals, Inc.

Wayne G Stuber

Charles L Newton

Kenneth William Kovak

David W Studer

Michael A Patterson

Arthur R Winters Jr

The present invention relates to an improved process for the reliquefaction of boil-off gas containing up to 10% nitrogen resulting from the evaporation of liquefied natural gas (LNG) contained in a storage vessel. In the process, a closed-loop nitrogen refrigeration cycle is utilized wherein the nitrogen is isenthalpically expanded under conditions for generating a liquid and vapor with the liquid being pressurized by pumping and warmed against an initially cooled boil-off stream. The boil-off LNG stream is initially cooled by indirect heat exchange with an isentropically expanded refrigerant stream.

Reliquefaction of boil-off from liquefied natural gas

The present invention is directed to a process for the purification and liquefaction of helium from a feed stream consisting essentially of nitrogen and helium with some minor impurities, wherein the helium is purified in a two step process: the first purification step comprising refrigerating the feed stream to condense nitrogen and any impurities from the feed stream, feeding the cooled feed stream to a separator, and removing from the bottom of the separator the condensed nitrogen and impurities in the feed stream and from the top of the separator a gaseous, high-helium-content stream; the second purification step comprising warming the gaseous, high-helium-content stream from the first purification step, feeding said stream to a pressure swing adsorber, and removing from the pressure swing adsorber an essentially pure helium stream, which is liquefied by feeding said essentially pure helium stream to a liquefier; wherein refrigeration is provided for the warm end of the liquefier and the two step purification; the improvement comprising providing said refrigeration by compressing a side stream of the essentially pure helium in a compressor and expanding said compressed stream in an expansion engine thereby producing a cold helium gas stream; splitting said cold helium stream into two substreams and circulating said cold helium gas stream to the warm end of the liquefier and to the two step purification to provide refrigeration duty.

Combined process to produce liquid helium, liquid nitrogen, and gaseous

A system for liquefying and subcooling natural gas wherein compression power is shifted off the closed cycle refrigerant by subcooling the liquid natural gas to a relatively warm exit temperature and subsequently reducing the pressure and flashing the liquefied natural gas to recover a gaseous phase natural gas in excess of plant fuel requirements, the excess being recompressed and recycled to the feed to the process.

Deep flash LNG cycle

A process and system are set forth for precooling, liquefying and subcooling a methane-rich feed stream, such as natural gas, with two closed circuit multicomponent refrigerant cycles in which the first refrigerant comprises a binary mixture of propane and butane in a flash refrigeration cycle and the second refrigerant comprises a mixture of nitrogen, methane, ethane, propane and butane in a subcool refrigeration cycle. The first refrigerant preferably cools the feed stream in a plate and fin heat exchanger.

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Whitehall, PA, United States of America

Wayne G Stuber