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.

A single compressor is used to separately compress permeate from cascaded first and second gas separation membrane-based separation units and residue from a fourth gas separation membrane-based separation unit in order to avoid too high a CO2 partial pressure in the compressed permeate. After the permeates from the first and second stages are compressed, the compressed stream is fed to a third gas separation membrane-based separation unit.

Process for producing biomethane from a biogas stream including methane, carbon dioxide and at least one impurity chosen from ammonia, volatile organic compounds, water, sulfur-based impurities (H.sub.2S) and siloxanes. A biogas stream is dried, the at least one impurity is at least partially removed by solidification and removal of the impurity. The methane and the carbon dioxide contained in the biogas obtained from the second step are separated so as to produce a biomethane stream and a CO.sub.2 stream.

A process for recovering at least one fluid (e.g. xenon gas and/or krypton gas, etc.) from a feed gas can include utilization of a compression system, primary heat exchanger unit, a pre-purification unit (PPU), and other units to separate and recover at least one desired fluid. In some embodiments, fluid flows output from a first heat exchanger or separation system of the plant can be split so that a portion of a stream is output for downstream processing to purify xenon (Xe) and/or krypton (Kr) product flow(s) while another portion of the stream is recycled to a compression system or the PPU to undergo further purification and heat exchange so that the product output for downstream processing has a higher concentration of Xe or Kr. Some embodiments can be configured to provide an improved recovery of Xe and/or Kr as well as an improvement in operational efficiency.

An apparatus for producing a purified, pressurized liquid carbon dioxide stream includes a distillation column (B) having packing (C) therein and a sump (D) below the packing, the distillation column in fluid communication with the liquid carbon dioxide supply tank for receiving the liquid carbon dioxide stream and the packing stripping volatile impurities from the liquid carbon dioxide stream; a heater (E) in contact with the liquid carbon dioxide stream in the sump (D) for vaporizing the liquid carbon dioxide stream in the sump; a vent in the distillation column (B) from which a first vaporized portion (G) of carbon dioxide vapor in the sump (D) is withdrawn from the distillation column: and a conduit (I) in fluid communication with the sump (D) and from which a second vaporized portion (H) of the carbon dioxide vapor in the sump is withdrawn into the conduit (I) to be introduced into the carbon dioxide vapor feed stream.

A system for removing acid gases from a raw gas stream is provided. The system includes a cryogenic distillation column. The cryogenic distillation column receives a dehydrated and chilled sour gas stream, and separates the sour gas stream into an overhead gas stream comprised primarily of methane, and a bottom acid gas stream comprised primarily of carbon dioxide. The system also includes a series of co-current contactors. The co-current contactors may be placed in series to receive the bottom acid gas stream and recapture any entrained methane gas. Alternatively or in addition, the co-current contactors may be placed in series to receive the overhead gas stream, and sweeten it using a reflux liquid such as methane. In this instance, the sweetened gas is optionally liquefied and delivered for commercial sale, or is used as fuel gas on-site.

The present disclosure provides a method for separating a feed stream in a distillation tower. The method includes operating a controlled freeze zone section in a distillation tower that separates a feed stream at a temperature and pressure at which the feed stream forms a solid in the controlled freeze zone section, wherein the feed stream includes a first contaminant; maintaining a melt tray assembly in the controlled freeze zone section; introducing the feed stream to the controlled freeze zone section; and accumulating a liquid in the melt tray assembly until the liquid is at a predetermined liquid level in the controlled freeze zone section, by: feeding a second contaminant to the controlled freeze zone section; and adding the second contaminant to the melt tray assembly, wherein the liquid comprises the second contaminant.

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.

Light gases such as helium are extracted from a carbon dioxide-containing feed stream by distillation. Costly dehydration steps are avoided by pumping the liquid bottoms stream leaving the distillation column without vaporization so as to ensure that any water present in the feed remains in solution with the bulk stream leaving the process. This prevents any liquid phase water causing corrosion or solid ice or hydrates forming to plug the flow.

A method of simultaneously liquefying CO2 and cooling natural gas, including providing a compressed CO2 loop, comprising a pressurized cooling stream, wherein a first compressed cooling stream and a second compressed cooling stream are produced by a CO2 compressor. Providing at least a portion of the first compressed cooling stream to a CO2 liquefaction system, wherein the first compressed cooling stream provides at least a portion of the refrigeration required by the CO2 liquefaction system. Providing at least a portion of the second compressed cooling stream to the pre-cooling system of a natural gas liquefaction system, wherein the second compressed cooling stream provides at least a portion of the refrigeration required by the natural gas pre-cooling.