The invention relates to a method for separating air by cryogenic distillation in a set of columns including a first column operating at a first pressure, a second column operating at a second pressure which is lower than the first pressure, and a third column operating at a third pressure, which is lower than the second pressure, wherein the third column includes first and second evaporator-condensers, and nitrogen from a cold compressor is sent to one of the evaporator-condensers.

An apparatus for the production of air gases with variable liquid production by the cryogenic separation of air can include a cold box having a heat exchanger, and a system of columns; a pressure monitoring device; and a controller. The cold box can be configured to receive a purified and compressed air stream under conditions effective for cryogenically separating the air stream to form an air gas product. The apparatus may also include means for transferring the air gas product from the cold box to an air gas pipeline. The pressure monitoring device is configured to monitor the pipeline pressure, and the controller is configured to adjust the product pressure of the air gas product coming out of the cold box based upon the pipeline pressure and to further adjust liquid production from the cold box based on the adjusted product pressure.

A system for natural gas cooling using nitrogen. The system can include a nitrogen liquefier and a natural gas cooler. The nitrogen liquefier can provide liquid nitrogen to the natural gas cooler. One or more heat exchangers of the natural gas cooler can include a gaseous nitrogen output that is in fluid communication with the nitrogen liquefier. In response to receiving gaseous nitrogen at the nitrogen liquefier, from the one or more heat exchangers, a production rate of the the nitrogen liquefier is adjusted.

A system and method for the production and supply of a densified, liquid oxidant to a space vehicle launch facility is provided. A stream of liquid oxygen taken from a co-located, liquid producing air separation unit is densified in a two refrigeration stage, integrated densification system. The first refrigeration stage is a nitrogen based reverse Brayton cycle refrigeration cycle that provides refrigeration to the second refrigeration stage. The second refrigeration stage is a helium and/or neon comprising refrigerant loop that densifies the liquid oxygen to a temperature between about 70 Kelvin and 57 Kelvin. The integrated densification system may also be configured to densify liquid methane or other propellants used in space vehicle launches.

Helium can be recovered from nitrogen-rich natural gas at high pressure with low helium loss by cryogenic distillation of the natural gas after pre-treatment of the gas to remove incompatible impurities and then recovery of natural gas liquid (NGL) from the pre-treated gas by distillation. Overall power consumption may be reduced, particularly if the feed to the helium recovery column system is at least substantially condensed by indirect heat exchange against a first portion of nitrogen-enriched bottoms liquid at first pressure, and a second portion of nitrogen-enriched bottoms liquid at a second pressure that is different from the first pressure.

Overall power consumption in a cryogenic distillation process for recovering helium from nitrogen-rich gases comprising helium may be reduced if the feed to the distillation column system is at least substantially condensed by indirect heat exchange against a first bottoms liquid at first pressure, and a second bottoms liquid at a second pressure that is different from the first pressure.

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.

A liquefier device which may be a retrofit to an air separation plant or utilized as part of a new design. The flow needed for the liquefier comes from an air separation plant running in a maxim oxygen state, in a stable mode. The three gas flows are low pressure oxygen, low pressure nitrogen, and higher pressure nitrogen. All of the flows are found on the side of the main heat exchanger with a temperature of about 37 degrees Fahrenheit. All of the gasses put into the liquefier come out as a subcooled liquid, for storage or return to the air separation plant. This new liquefier does not include a front end electrical compressor, and will take a self produced liquid nitrogen, pump it up to a runnable 420 psig pressure, and with the use of turbines, condensers, flash pots, and multi pass heat exchangers. The liquefier will make liquid from a planned amount of any pure gas oxygen or nitrogen an air separation plant can produce.

The present invention relates to a method and system for producing liquefied natural gas (LNG) from a stream of pressurized natural gas which involves a combination of mechanical refrigeration.

A device for recovering variable low-temperature gas includes a low temperature stabilizing system, a compression system, an expansion refrigeration system, and a heat exchange system, which are connected to each other by pipelines, where the low temperature stabilizing system is composed of a liquid storage unit, a liquid delivery unit, a liquid jet gasification mixing unit, and a control unit, for regulating the temperature of low-temperature gas; a liquid outlet channel of the liquid storage unit is connected to a liquid inlet channel of the liquid delivery unit, a liquid outlet channel of the liquid delivery unit is connected to a liquid inlet channel of the liquid jet gasification mixing unit, and the compression system is composed of a raw material compressor and a circulating compressor; and a gas outlet channel of the raw material compressor is connected to a gas inlet channel of the circulating compressor.