The invention relates to a process for low-temperature separation of air, in which an air separation plant having a first rectification column and a second rectification column is used, the first rectification column being supplied with cooled compressed air and the second rectification column being supplied with liquid from the first rectification column or liquid formed herefrom. By means of a first condenser-evaporator, head gas of the first rectification column is condensed and liquid from the second rectification column or liquid formed herefrom is evaporated, thereby producing a first evaporation product. The invention also relates to a corresponding air separation plant.

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 nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

A nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

A nitrogen producing cryogenic air separation unit with an excess air circuit is provided. The nitrogen producing cryogenic air separation unit is capable of producing high pressure gaseous nitrogen without the use of a nitrogen product compressors and is also capable of producing high rates of liquid nitrogen without adding additional compression stages in the main air compressor and/or without a nitrogen recycle compressor.

A dual-mode LNG liquefier arrangement that is configurable to operate in a first mode broadly characterized as a low pressure, liquid nitrogen add LNG liquefier without turbo-expansion or a second mode broadly characterized as a low pressure, liquid nitrogen add LNG liquefier with turbo-expansion.

The present disclosure provides a carbon-based oxygen-enriched combustion method for recirculation of flue gas from a cement kiln. The combustion method includes recirculating the flue gas generated by the cement kiln to a certain degree to concentrate and enrich carbon dioxide in the flue gas of the cement kiln, mixing the carbon dioxide-rich recirculating flue gas of the cement kiln with the pressurized oxygen to obtain the carbon-based oxygen-enriched products, and mixing the carbon-based oxygen-enriched products with the atmospheric-pressure oxygen to obtain carbon-based air which serves as combustion-supporting gas of the cement kiln.

A nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

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.