The present disclosure relates to the technical field of natural gas power generation, and particularly discloses a natural gas combined power generation process with zero carbon emission, the process comprising: introducing the pressurized air into an air separation facility to obtain liquid oxygen and liquid nitrogen, wherein the liquid oxygen is used for gasification and power generation, the liquid nitrogen is applied as the coolant of flue gas, and then used for the gasification and power generation; the liquid nitrogen and a part of liquid oxygen stored during the valley period with low electricity load are provided for use during the peak period with high electricity load; the natural gas, oxygen and the recyclable CO.sub.2 jointly enter a combustion gas turbine for burning to drive an air compressor and a generator to rotate at a high speed, the air compressor compresses the air to a pressure of 0.40.8 MPa, the generator generates electricity; the high-temperature combustion flue gas performs the supercritical CO.sub.2 power generation, its coolant is liquid oxygen; the moderate temperature flue gas then exchanges heat with liquid nitrogen, the liquid nitrogen vaporizes for power generation, the cooled flue gas is dehydrated and subjects to distillation and separation to obtain the recovered CO.sub.2, a part of the CO.sub.2 can be returned for circulation and temperature control, another part of the CO.sub.2 may be used for replenishment of work medium for supercritical CO.sub.2 power generation, and the remaining part of CO.sub.2 may be sold outward as liquid CO.sub.2 product. During the peak period with high electricity load, the liquid nitrogen stored during the valley period with low electricity load and separated during the peak period is pumped and pressurized and then subjects to heat exchange and vaporization for power generation. The power generation process provided by the present disclosure not only solves the difficult problems in the existing natural gas combined power generation technology such as high water consumption, low power generation efficiency and small range of peak load adjustment capacity; but also can compress air with high unit volume for energy storage with a high conversion efficiency, and greatly reduce load of the air compressor, thereby perform CO.sub.2 capture and utilization with low cost, zero NO.sub.x emission and discharging fuel gas at a normal temperature, and significantly improve the power generation efficiency.

In a method for reheating an atmospheric vaporizer, a cryogenic liquid is vaporized by heat exchange with ambient air in the atmospheric vaporizer and to reheat the vaporizer, a gas is sent thereto at a temperature of at least 0 C., this gas originating from a cryogenic distillation air separation unit.

The method for reducing or removing non-volatile impurities in a high-purity oxygen liquid comprises: an oxygen vaporization step for vaporizing a high-purity oxygen liquid obtained from a high-purity oxygen rectification column in an air separation unit for producing the high-purity oxygen liquid; and an oxygen recondensing step for recondensing oxygen gas vaporized in the oxygen vaporization step. This method may also comprise a high-purity oxygen liquid extraction step for extracting a condensate obtained in the oxygen recondensing step.

Process and apparatus for the separation of a compressed feed air stream to produce an oxygen product using a distillation column having a lower-pressure column and a higher-pressure column, a higher-pressure heat exchanger and a lower-pressure heat exchanger where the gaseous nitrogen expander receives a nitrogen-enriched fraction from a position intermediate the warmer end and the colder end of the higher-pressure heat exchanger.

The method and the device arc used for the cryogenic decomposition of air in a distillation column system for separating nitrogen and oxygen, said system having a first high-pressure column (23), a low-pressure column (25, 26), and three condenser-evaporators, namely a high-pressure column head condenser (27), a low-pressure column bottom evaporator (28), and an auxiliary condenser (29; 228).

The invention relates to a method and device for generating two purified partial air streams under different pressures. A total air stream (1) is compressed to a first total air pressure. The compressed total air stream (5) is cooled with cooling water under the first total air pressure by way of heat exchange (4, 6). The heat exchange with cooling water for cooling the total air stream (5) is carried out as a direct heat exchange in a first direct contact cooler (6), at least in part. The cooled total air stream (9) is divided into a first partial air stream (10) and a second partial air stream (11). The first partial air stream (10) is purified in a first purification device (18) under the first total air pressure, generating the first purified partial air stream (19). The second partial air stream (11) is re-compressed to a higher pressure (12), which is higher than the first total air pressure. The re-compressed second partial air stream (14) is cooled with cooling water in a second direct contact cooler (15) by way of direct heat exchange (13, 15). The cooled second partial air stream (17) is purified under the higher pressure in a second purification device (30), thus generating the second purified partial air stream (31).

A method and backup system for backing up a supply oxygen in an air separation plant in which during normal operation, a stream of oxygen-rich liquid is pumped through a main flow path, extending from a surge tank to a heat exchanger, to deliver an oxygen product. The surge tank receives the oxygen-rich liquid from a bottom region of the lower pressure column of the plant. Additionally, during normal operations, a stream of the oxygen-rich liquid is also introduced to a reserve storage tank through a backup flow path. During a transient operation, where the air separation plant has ceased operation, the surge tank is isolated and liquid is pumped from the surge tank through an auxiliary flow path to an auxiliary vaporizer to continue the supply of the oxygen product and the surge tank is replenished with oxygen-rich liquid previously stored in the reserve storage tank.

A method of liquid air energy storage is provided. This method includes liquefying and storing air to form a stored liquid air during a first period of time; during a second period of time, introducing a compressed air stream into a cryogenic system, wherein the cryogenic system comprises at least one cold compressor, and at least one heat exchanger. The method includes producing a first exhaust stream and a second exhaust stream. The method also includes vaporizing at least part of the stored liquid air stream in the heat exchanger, thereby producing a first high pressure compressed air stream, then combining the first high pressure compressed air stream, the first exhaust stream and the second exhaust stream to form a combined exhaust stream, heating the combined exhaust stream, then expanding the heated combined exhaust stream in an expansion turbine to produce power.

In a method for reheating an atmospheric vaporizer, a cryogenic liquid is vaporized by heat exchange with ambient air in the atmospheric vaporizer and to reheat the vaporizer, a gas is sent thereto at a temperature of at least 0 C., this gas originating from a cryogenic distillation air separation unit.

Recovering xenon and/or krypton from a feed gas can include utilization of a purge stream from a separation column positioned and configured to output at least one stream of fluid that is substantially nitrogen and at least one stream of fluid that is substantially oxygen. The purge stream can be split so that a first portion of the purge stream is fed as a liquid adjacent to a top of a purge treatment column and a second portion of the purge stream can be fed to a heat exchanger for superheating the second portion to feed a superheated vapor at or adjacent to a bottom of the purge treatment column. The purge treatment column can output a liquid stream that has a relatively high concentration of Xe and/or Kr therein as a feed stream for an Xe and/or Kr recovery system.