In a helium purification process, a stream containing at least 10% of helium, at least 10% of nitrogen in addition to hydrogen and methane is separated to form a helium-enriched stream containing hydrogen, a first stream enriched in nitrogen and in methane and a second stream enriched in nitrogen and in methane, the helium-enriched stream is treated to produce a helium-rich product and a residual gas containing water, the residual gas is treated by adsorption (TSA) to remove the water and the regeneration gas from the adsorption is sent to a combustion unit (O).

A method to pre-treat an inlet natural gas stream at gas pressure reduction stations to produce LNG removes water and carbon dioxide from a natural gas stream. The energy required for the process is provided by recovering pressure energy in the inlet gas stream. The process eliminates the conventional gas pre-heating process at pressure reductions stations employing gas combustion heaters. The process provides a method to produce LNG at natural gas pressure reduction that meets product specifications.

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.

An energy efficient process for NGL recovery and production of compressed natural gas (CNG) in which natural gas is fed to a first gas separation membrane-based separation stage where it is separated into a permeate and a retentate. The high C.sub.3+ concentration first stage permeate is chilled and separated to provide liquid phase NGL and a gaseous phase. The first stage retentate is separated at a second gas membrane-based separation stage to produce a retentate meeting pipeline specifications for CNG (including hydrocarbon dewpoint) and a permeate that is recycled to the first stage. The gaseous phase, constituting a low BTU fuel, may be used in on-site power generation equipment and/or in internal combustion engines. The second stage permeate (and optionally the third stage retentate) is (are) recycled back to the first stage to enhance the production of NGL and CNG. The gaseous phase may instead be fed to a third stage to produce a third permeate and a third residue, in which case the third permeate is recycled to the first stage and the third retentate is a low BTU fuel which may be used in on-site power generation equipment and/or in internal combustion engines.

The present disclosure provides systems and methods useful in capture of one more moieties (e.g., carbon dioxide) from a gas stream (i.e., direct air capture). In various embodiments, the systems and methods can utilize at least a scrubbing unit, a regeneration unit, and an electrolysis unit whereby an alkali solution can be used to strip the moiety (e.g., carbon dioxide) from the gas stream, the removed moiety can be regenerated and optionally purified for capture or other use, and a formed salt can be subjected to electrolysis to recycle the alkali solution back to the scrubber for re-use with simultaneous production of one or more further chemicals.

Disclosed are a facility and a method using the facility for treating a feed gas stream comprising at least methane and carbon dioxide by membrane permeation, the facility comprising: —a first membrane separation unit capable of receiving the feed gas stream and providing a first permeate and a first retentate, —a second membrane separation unit capable of receiving the first retentate and providing a second permeate and a second retentate, —a compressor for compressing the first permeate to a pressure of between 17 bar and 25 bar, —a means for cooling the first compressed permeate to a temperature lower than −40° C., —a distillation column for separating the first cooled permeate into a gas stream and a liquid stream, —at least one means for recycling the gas stream exiting the distillation column to the inlet of the first membrane separation unit, —a means for measuring the concentration of methane and/or carbon dioxide in the gas stream exiting the distillation column, —a means for comparing the concentration of methane and/or carbon dioxide measured by the measurement means with a target value, and —a means for adjusting the pressure and/or the temperature of the first permeate depending on the comparison carried out by the comparison means.

The present invention relates to a method and system for producing liquefied natural gas (LNG) from a stream of pressurized natural gas which involves a combination of mechanical refrigeration.

Processes and systems for recovering hydrogen may include feeding a gas stream, comprising hydrogen and additional gases, to a pressure swing adsorption (PSA) system and feeding a membrane permeate stream comprising hydrogen to the PSA system. In the PSA system, a portion of the hydrogen may be separated from the additional gases to recover a hydrogen product stream and a PSA tail gas stream comprising unseparated hydrogen and the additional gases. The PSA tail gas stream may be fed to a membrane separation unit for separating hydrogen from the additional gases and to recover (i) the membrane permeate stream comprising hydrogen fed to the PSA system and (ii) a membrane tail gas stream comprising the additional gases. Embodiments herein may additionally include a refrigeration system for partially condensing one or both of the feed gas stream and the PSA tail gas stream, enhancing the efficiency of the membrane separation unit.

A system and method for producing acetic acid, including dry reforming methane with carbon dioxide to give syngas, cryogenically separating carbon monoxide from the syngas giving a first stream including primarily carbon monoxide and a second stream including carbon monoxide and hydrogen. The method includes synthesizing methanol from the second stream via hydrogenation of carbon monoxide in the second stream, synthesizing dimethyl ether from the methanol, and generating acetic acid from the dimethyl ether and first-stream carbon monoxide.

The present invention relates to an improved method for removing contaminants from a gaseous stream substantially comprising carbon dioxide. More specifically, the method comprises the step of subjecting the gaseous stream to an absorption step in which the absorbent is liquid carbon dioxide wherein the waste of carbon dioxide is minimized by utilizing a compressing means for generating a pressure difference between two streams in a reboiler.