A facility for recovering carbon dioxide from a feed gas flow, including a unit for treating the feed gas flow in order to produce, from feed gas flow, a carbon dioxide-rich gas flow and a nitrogen-rich gas flow, a compression stage for compressing the feed gas flow, an expansion stage capable of outputting mechanical energy generated by the expansion of the nitrogen-rich gas flow, a thermal device arranged to enable heat transfers to take place between the gas flow leaving the compression stage and the nitrogen-rich gas flow prior to expansion, and a device for utilising the mechanical energy output by the expansion stage.

A system for capturing carbon dioxide from an industrial gas as a solidified carbon dioxide. The system directs an exhaust gas stream at an initial mean temperature to a compressor and a cooling assembly to bring the compressor stream down to an initial cooling temperature between the mean temperature and a de-sublimation temperature for the carbon dioxide gas in the stream. A work extraction mechanism is then used to condense the carbon dioxide from the stream into a solid form by work extraction and in substantial absence of surface accretion within the system.

A desublimating heat exchanger receives a cooled process gas stream from a pre-cool heat exchanger and includes a clean gas outlet, a contact liquid inlet and a slurry outlet. A contact liquid heat exchanger communicates with the contact liquid inlet of the desublimation heat exchanger and warms a liquid natural gas stream to provide cooling within the contact liquid heat exchanger. The desublimating heat exchanger contacts the cooled process gas stream with the cooled contact liquid so that carbon dioxide is absorbed within the contact liquid whereby a carbon dioxide laden slurry stream and a carbon dioxide depleted clean process gas stream are formed. The clean process gas stream passes through the clean gas outlet to the pre-cool heat exchanger and the slurry stream passes through the slurry outlet. The pre-cool heat exchanger warms the clean process gas stream to provide cooling for the process gas stream. A solid separation device communicates with the contact inlet of the desublimating heat exchanger and separates the carbon dioxide laden slurry stream from the desublimating heat exchanger into a condensed carbon dioxide stream and a contact liquid stream.

Processes for recovery of carbon dioxide from a flue gas stream and removal of NOx compounds from the recovered carbon dioxide are described. The processes can recover gaseous, liquid, or supercritical carbon dioxide. The processes incorporate a NOx stripping column after the CO.sub.2 fractionation column to remove NOx compounds formed in the CO.sub.2 fractionation column.

The invention relates to a method for the low-temperature separation of a gas containing CO.sub.2 in order to produce a CO.sub.2-rich fluid, in which method a gas containing CO.sub.2 and at least one component lighter than CO.sub.2 is compressed in a compressor comprising at least two stages, the gas being cooled downstream of at least one of the stages in a cooler and by exchanging heat with air and then being cooled in a first heat exchanger, the gas cooled in the first heat exchanger is separated at low temperature by partial condensation and/or distillation in order to produce a fluid rich in CO.sub.2 and depleted in the component lighter than CO.sub.2 and a gas depleted in CO.sub.2 and enriched in the component lighter than CO.sub.2. The gas depleted in CO.sub.2 is first heated in the first heat exchanger and then in the cooler before being expanded in a turbine.

The invention relates to a method for the low-temperature separation of a feed gas containing CO.sub.2, at least one component lighter than CO.sub.2 and at least one component heavier than CO.sub.2, wherein, in order to produce a CO.sub.2-rich fluid, the feed gas is compressed, the compressed gas being cooled in a first heat exchanger, the gas cooled in the first heat exchanger is separated at low temperature in a first distillation column to produce a liquid that is enriched in CO.sub.2 and depleted in the at least one component lighter than CO.sub.2 and a gas that is depleted in CO.sub.2 and enriched in the at least one component lighter than CO.sub.2, the gas depleted in CO.sub.2 is heated in the first heat exchanger, a first part of the liquid enriched in CO.sub.2 is expanded and sent to a second distillation column in liquid form, a second part of the liquid enriched in CO.sub.2 is vaporized in the first heat exchanger then sent in gas form into the tank of the second distillation column, a liquid depleted in CO.sub.2 and enriched in the at least one heavier component is withdrawn from the second column, and a gas enriched in CO.sub.2 and depleted in the at least one heavier component is withdrawn at the top of the second column as product.

A process for separating a gas mixture, a first item of equipment of the process is heated by a first flow of a first heat producer and supplies heat to a first fluid, the first flow of heat producer being heated upstream of the first item of equipment by a heat source, a second item of equipment of the process heats a second fluid while consuming heat, the heat originating from a second flow of the first heat producer heated by the heat source, which heats the second flow of the first heat producer up to an intermediate temperature lower than the second temperature, and by a heater downstream of the source, which heats the second flow of the first heat producer, which has been heated by the heat source, from the intermediate temperature up to a second temperature higher than the first temperature.

The carbon capture process includes, under normal operation: a first stream is compressed, dried, cooled and separated by partial condensation step a phase separator forming a liquid enriched in CO2 and a gas enriched in the at least one component lighter than CO2. And the gas enriched in the component lighter than CO2 is warmed in the heat exchanger and then expanded in a turbine, and then is sent to the atmosphere or to a cooling tower. Under start-up conditions, a phase separator is at a first temperature and a second stream of a gaseous mixture containing CO2 and at least one component lighter than CO2 is expanded in the turbine to produce an expanded gas at a second temperature different from the first temperature, the expanded gas being then warmed in the heat exchanger or sent to be separated in a distillation column of the carbon capture process.