A method comprising the cooling of the feed natural-gas (15) in a first heat exchanger (16) and the introduction of the cooled feed natural-gas (40) in separator flask (18). The method further comprising dynamic expansion of a turbine input flow (46) in a first expansion turbine (22) and the introduction of the expanded flow (102) into a splitter column (26). This method includes sampling at the head of the splitter column (26) a methane-rich head stream (82) and sampling in the compressed methane-rich head stream (86) a first recirculation stream (88). The method comprises the formation of at least one second recirculation stream (96) obtained from the methane-rich head stream (82) downstream from the splitter column (26) and the formation of a dynamic expansion stream (100) from the second recirculation stream (96).

In a method for compressing a gas that is to be separated in a low-temperature CO.sub.2 separation unit using at least one partial condensation step and/or at least one distillation step, the gas that is to be separated has a variable composition and/or variable flow rate, the gas that is to be separated is compressed in a compressor to produce a compressed gas and the inlet pressure of the gas that is to be separated, entering the compressor, is modified according to the CO.sub.2 content and/or the flow rate of the gas that is to be separated so as to reduce the variations in volumetric flow rate of the gas that is to be separated entering the compressor.

Systems and methods that utilize feed gases that are supplied in a wide range of compositions and pressure to provide highly efficient recovery of NGL products, such as propane, utilizing isenthalpic expansion, propane refrigeration, and shell and tube exchangers are described. Plants utilizing such systems and methods can be readily reconfigured between propane recovery and ethane recovery.

A system for removing freezing components from a feed gas includes a heavy hydrocarbon removal heat exchanger and a scrub device. The scrub device includes a scrub column that receives a cooled feed gas stream from the heat exchanger and a reflux separation device. Vapor from the scrub column is directed to the heat exchanger and cooled to create a reflux stream that includes a liquid component. This reflux stream is directed to the reflux separation device and a resulting liquid component stream is used to reflux the column. Vapor from the reflux separation device is expanded and directed to the heat exchanger, where it provides refrigeration, and a processed feed gas line.

Processes and systems for recovery of a dilute ethylene stream are illustrated and described. More specifically, embodiments disclosed herein relate to processes and systems for separation of a dilute ethylene stream from an offgas or other vapor streams, where the ultra-low temperature refrigeration for the desired separations is provided by the offgas itself, and only moderately-low temperature externally supplied propylene refrigerants (for example, at 40 C. to 15 C.) are necessary.

A thermoacoustic refrigerator includes at least one pair of pulse combustion tubes (10), preferably Rijke tubes, each tube (10) having a pair of spaced-apart Stirling engines (12), coupled together but with no separating membrane therebetween.

A thermoacoustic refrigerator includes at least one pair of pulse combustion tubes (10), preferably Rijke tubes, each tube (10) having a pair of spaced-apart Stirling engines (12), coupled together but with no separating membrane therebetween.

The invention relates to an apparatus for cryogenic separation of a mixture of carbon monoxide, hydrogen and nitrogen, including a stripping column and a denitrogenation column, a pipe for sending the mixture in liquid form to the head of the stripping column, a pipe for removing a liquid depleted of hydrogen connected to the stripping column, a pipe for removing a gas enriched with hydrogen from the stripping column, means for sending the liquid depleted of hydrogen or a fluid derived from said liquid to the denitrogenation column, a pipe for drawing a liquid enriched with carbon monoxide from the denitrogenation column, a pipe for drawing a gas enriched with nitrogen from the head of the denitrogenation column and means for sending at least one portion of the gas enriched with hydrogen to the denitrogenation column.

Systems and methods are provided for increasing the efficiency of liquefied natural gas production and heavy hydrocarbon distillation. In one embodiment, air within an LNG production facility can be utilized as a heat source to provide heat to HHC liquid for distillation in a HHC distillation system. The mechanism of heat transfer from the air can be natural convection. In another embodiment, heat provided by natural gas, or compressed natural gas, can be used for HHC distillation. In other embodiments, various other liquids can be used to transfer heat to HHC liquid for distillation.

An acid gas purification system is described herein that includes a primary membrane system with a CO.sub.2- and H.sub.2S-enriched permeate stream effluent and a hydrocarbon stream effluent; a first compression stage arranged to receive the CO.sub.2- and H.sub.2S-enriched permeate stream and produce a compressed stream; and a cryogenic separation system to receive the compressed stream, the cryogenic separation system including a cooler followed by a fractionator, wherein the fractionator produces a CO.sub.2- and H.sub.2S liquid stream and a hydrocarbon gas stream.