A BOG reliquefaction system includes: a compressor; a heat exchanger cooling the BOG compressed by the compressor through heat exchange using BOG not compressed by the compressor; a pressure reducer disposed downstream of the heat exchanger and reducing a pressure of fluid cooled by the heat exchanger; and a combination of a first temperature sensor disposed upstream of a cold fluid channel of the heat exchanger and a fourth temperature sensor disposed downstream of a hot fluid channel of the heat exchanger, combination of a second temperature sensor disposed downstream of the cold fluid channel of the heat exchanger and a third temperature sensor disposed upstream of the hot fluid channel of the heat exchanger, or combination of a first pressure sensor disposed upstream of the hot fluid channel of the heat exchanger and a second pressure sensor disposed downstream of the hot fluid channel of the heat exchanger.

A hydrogen feed stream comprising oxygen and one or more impurities selected from the group consisting of nitrogen, argon, methane, carbon monoxide, carbon dioxide, and water, is purified by first removing oxygen using a copper oxide and/or manganese oxide getter, then using a cryogenic temperature swing adsorption (CTSA) process with high overall recovery of hydrogen. The oxygen getter prevents an explosive mixture of hydrogen and oxygen from occurring in the CTSA during regeneration.

A hydrogen feed stream comprising one or more impurities selected from the group consisting of nitrogen, argon, methane, carbon monoxide, carbon dioxide, oxygen, and water, is contacted with liquid hydrogen in a cryogenic wash column (CWC) process that produces pure hydrogen with high overall recovery. The waste liquid stream leaving the CWC may be used to improve the performance of upstream hydrogen processing steps.

A hydrogen feed stream comprising oxygen and one or more impurities selected from the group consisting of nitrogen, argon, methane, carbon monoxide, carbon dioxide, and water, is purified using a cryogenic temperature swing adsorption (CTSA) process with high overall recovery of hydrogen. The CTSA is regenerated using an inert gas to prevent an explosive mixture of hydrogen and oxygen from occurring.

A natural gas liquefaction method and system having integrated nitrogen removal. Recycled LNG gas is cooled in a separate and parallel circuit from the natural gas stream in the main heat exchanger. Cooled recycled gas and natural gas streams are directed to a nitrogen rectifier column after the warm bundle. The recycle stream is introduced to the rectifier column above the natural gas stream and at least one separation stage is located in the rectifier column between the recycle stream inlet and the natural gas inlet. The bottom stream from the rectifier column is directed to a cold bundle of the main heat exchanger where it is subcooled.

Techniques and systems for separating components of a mixture of compressed gases each having different boiling points are described. One example system includes multiple recovery stages that each recover one of the gases by condensing it into liquid form. The recovery stages are chained together, such that each stage recovers a gas having a boiling point that is higher than those of the gases to be recovered in downstream stages. Each stage typically includes a warming element that is fluidly coupled to a condenser element that provides a surface cooled to a temperature low enough to condense one of the gases, but high enough such that the remaining gases remain in gaseous form. The system may include an initial evaporator stage that heats a liquid solution of phytochemical extracts and multiple solvents, thereby recovering the extracts and producing the mixture of gaseous solvents.

A bio-renewable conversion process for making fuel from bio-renewable feedstocks is combined with a hydrogen production process that includes recovery of CO.sub.2. The integrated process uses a purge gas stream comprising hydrogen from the bio-renewable hydrocarbon production process in the hydrogen production process.

A process and apparatus for producing a hydrogen-enriched product and recovering CO.sub.2 from an effluent stream from a hydrogen production process unit are described. The process utilizes a CO.sub.2 recovery system integrated with a PSA system that produces at least two product streams to recover additional hydrogen and CO.sub.2 from the tail gas stream of a hydrogen PSA unit in the hydrogen production process.

A process and apparatus for producing a hydrogen-enriched product and recovering CO.sub.2 from an effluent stream from a hydrogen production unit are described. The effluent from the hydrogen production unit, which comprises a mixture of gases comprising hydrogen, carbon dioxide, water, and at least one of methane, carbon monoxide, nitrogen, and argon, is sent to a PSA system that produces at least two product streams for separation. The PSA system that produces at least two product streams separates the gas mixture into a high-pressure hydrogen stream enriched in hydrogen, optionally a second gas stream containing the majority of the impurities, and a low-pressure tail gas stream enriched in CO.sub.2 and some impurities. The CO.sub.2-rich tail gas stream is compressed and sent to a CO.sub.2 recovery unit, where a CO.sub.2-enriched stream is recovered. The CO.sub.2-depleted overhead gas stream is recycled to the PSA system that produces at least two product streams.

The present invention comprises systems and methods for natural gas liquefaction. In embodiments, the systems comprise a dual turbo-expander, methane-based refrigeration system that also uses a slip stream of LNG for additional cooling.