In a process for separating at least one heavy impurity such as hydrogen sulfide from crude carbon dioxide comprising significant quantities of at least one light impurity such as non-condensable gases, involving at least one heat pump cycle using carbon dioxide-containing fluid from the process as the working fluid, the light impurity is removed from the crude carbon dioxide and carbon dioxide is subsequently recovered from the removed light impurity, thereby improving overall carbon dioxide recovery and efficiency in terms of energy consumption.

In a process for separating a mixture containing hydrogen and carbon dioxide, the following steps are present: a) cooling of the mixture in a heat exchanger by sending the mixture to the heat exchanger, resulting in the partial condensation of the mixture into a liquid phase enriched in carbon dioxide and a gas phase depleted in carbon dioxide, a gaseous fluid which is heated in the heat exchanger by indirect heat exchange, b) separating the liquid phase from the gas phase in a separator vessel, c) heating of the gas phase originating from at least one of the separator vessels in the heat exchanger, d) sending of the at least one heated part from step c) to a membrane separation unit, generating a residue depleted in hydrogen and carbon dioxide and e) expansion of the at least one residue in a turbine producing an expanded fluid, f) the expanded fluid constituting the gaseous fluid of step a) which is heated in the heat exchanger by indirect heat exchange.

In a process for separating a mixture containing hydrogen and carbon dioxide, the mixture is compressed to form a compressed mixture, the compressed mixture is separated by partial condensation and/or distillation generating a first CO2-depleted stream, the first CO2-depleted stream is separated by permeation through a membrane system to form a residue of the membrane system which is depleted in hydrogen and carbon dioxide and a portion of the residue is recycled, after expansion, to the compressor to be compressed therein.

A method for liquefying a CO2-rich gas flow containing at least 90 mol % of CO2 involves the following steps: compressing the CO2-rich gas flow, liquefying and separating in order to produce a first liquid flow at a first pressure MP and a first temperature T1. Extracting part of the first liquid flow at the first pressure and the first temperature by way of first product, supercooling part of the first liquid flow down to a temperature below the first temperature by indirect exchange of heat in a heat exchanger, expanding the liquid supercooled down to the second temperature T2 until it reaches a second pressure lower than the first pressure, the second pressure being equal to or greater than the equilibrium pressure of the expanded liquid, and extracting part of the expanded liquid by way of second product and evaporating another part of the liquid in the heat exchanger by exchange of heat with the part of the first flow in order to produce a vaporized liquid.

A system captures carbon dioxide from a flue gas of a power generation facility by using cold heat of liquefied natural gas and utilizes the captured carbon dioxide for mining natural gas, using heat of the flue gas to regasify the LNG. Solidified dry ice is captured from gaseous carbon dioxide contained in the flue gas, and the captured dry ice is used as filler when mining natural gas. The system includes a mining facility, a vehicle to transport LNG liquefied by the mining facility; and a facility for regasifying the transported LNG and capturing dry ice from the carbon dioxide. In the regasification and capture facility, the flue gas exchanges heat with the LNG, thereby regasifying the LNG at an increased temperature and capturing the dry ice from the carbon dioxide. The captured dry ice is transported to the mining facility, which uses it for mining the natural gas.

The present invention relates to a process and device for condensing a first fluid rich in carbon dioxide using a second fluid.

A carbon dioxide-rich mixture is cooled in a first brazed aluminum plate-fin heat exchanger, at least one fluid derived from the cooled mixture is sent to a purification step having a distillation step and/or at least two successive partial condensation steps, the purification step produces a carbon dioxide-depleted gas which heats up again in the first exchanger, the purification step produces a carbon-dioxide rich liquid which is expanded, then sent to a second heat exchanger where it is heated by means of a fluid of the method, the exchanger carrying out an indirect heat exchange only between the carbon dioxide-rich liquid and the fluid of the method, the carbon dioxide-rich liquid at least partially vaporizes in the second exchanger and the vaporized gas formed heats up again in the first exchanger to form a carbon dioxide-rich gas which can be the end product of the method.

A batch process for producing a purified, pressurized liquid carbon dioxide stream, includes withdrawing a liquid carbon dioxide stream (A) from a liquid carbon dioxide supply (10); introducing the liquid carbon dioxide stream (A) into a distillation column (B) having packing (C) therein, and stripping volatile impurities from the liquid carbon dioxide stream with the packing; vaporizing the liquid carbon dioxide stream (A) in a sump (D) of the distillation column (B) for providing a carbon dioxide vapor; withdrawing from a vaporized portion (F) of carbon dioxide vapor in the sump (D) a first vapor stream (G) vented from the distillation column (B); withdrawing from the vaporized portion (F) of the carbon dioxide vapor in the sump (D) a second vapor portion (H) vented from the sump into a conduit (I); and introducing the second vapor portion (H) in the conduit (I) into a carbon dioxide vapor feed stream.

A device for recovering carbon dioxide and nitrogen from flue gas includes a pretreatment system, a CO.sub.2and N.sub.2separation system, a N.sub.2purification and liquefaction system, and a CO.sub.2 purification and liquefaction system. The pretreatment system includes a high-temperature NG cooler, a gas-liquid separator, a booster fan, and a dryer; the CO.sub.2and N.sub.2 separation system includes a low-temperature LNG cooler and a cryogenic adsorption device; the N.sub.2 purification and liquefaction system includes a set of N.sub.2 distillation and liquefaction device consisting of a compressor, a cooler, a heat exchanger, a gas-liquid separator, and a distillation tower; and the CO.sub.2purification and liquefaction system includes a set of CO.sub.2 distillation and liquefaction device consisting of a compressor, a cooler, a condenser, an evaporator, a liquefier, and a purification tower, which are used for further purifying and liquefying desorbed gas obtained from the CO.sub.2and N.sub.2 separation system.

An apparatus for separation of a flow containing at least 95 mol % of carbon dioxide and also at least one impurity lighter than carbon dioxide by distillation comprises a heat exchanger (20), a distillation column (30), expansion means (V3), means for sending the flow to be cooled in the heat exchanger, means for sending the cooled flow to be separated in the distillation column, means for withdrawing at the bottom of the column a liquid flow containing at least 99 mol % of carbon dioxide, means for sending at least a portion (12) of the liquid flow to be cooled in the heat exchanger to form a subcooled liquid (3), means for sending at least a portion of the subcooled liquid to the expansion means to produce a two-phase flow, a phase separator (40) for separating the two-phase flow to form a gas and a liquid, means for sending at least a portion (14) of the liquid from the phase separator to be vaporized in the heat exchanger and means for taking a portion (4) of the liquid from the phase separator.