A method for obtaining an air product from an air separation plant having a distillation column system and a tank system. The tank system includes a first tank and a second tank. Cryogenic liquid is withdrawn from the distillation column system, stored in the tank system, and used as the air product. The cryogenic liquid is supplied to the first tank and withdrawn from the second tank during a first period, and is supplied to the second tank and withdrawn from the first tank during a second period. The tank system has a third tank to which cryogenic liquid withdrawn from the first tank and the second tank is transferred unheated. The air product is withdrawn from the third tank in liquid state, vaporized and discharged. Alternatively, the cryogenic liquid can be withdrawn from the third tank and stored in the liquid state in a fourth tank.

A nitrogen production system that can produce high purity nitrogen containing a desired concentration of oxygen and ultrahigh purity nitrogen containing a desired concentration of argon in a single rectifying column while restraining increase in electric power consumption, and a production process thereof are provided. The nitrogen production system includes a heat exchanger that cools material air, a nitrogen rectifying column including a rectifying unit into which the material air cooled by the heat exchanger is introduced and a condenser that is located in a column top, a first introduction pipe that introduces the material air from the heat exchanger into a buffer unit located at a lower part from a position of the rectifying unit, a second introduction pipe for introducing an oxygen-enriched liquefied gas into the condenser from the buffer unit of the nitrogen rectifying column, a first derivation pipe for deriving ultrahigh purity nitrogen from the rectifying unit and recovering the ultrahigh purity nitrogen, and a second derivation pipe for deriving high purity nitrogen from an intermediate plate of the rectifying unit and recovering the high purity nitrogen.

Provided is a packed column capable of achieving sufficiently high distillation performance even with the height of its gas-liquid contactors reduced. The packed column is a packed column which includes a gas-liquid contactor 17, 18 inside a tubular body 16 and a liquid distributor 19 in the upper most portion and causes descending liquid and ascending gas to contact each other in the gas-liquid contactor. The operation pressure is in the range of 200 to 1500 kPaG. The relative volatility is in the range of 1.9 to 3.1. The gas-liquid contactor is vertically divided into at least two parts. A gas disperser 20 is provided at at least one position between a lower one of the gas-liquid contactors and an upper one of the gas-liquid contactors, the gas disperser uniformly dispersing the composition of the ascending gas rising from the lower gas-liquid contactor toward the upper gas-liquid contactor.

An ultra-high-purity oxygen production method and apparatus are provide, in which the method can include a step in which feed oxygen comprising low-boiling-point components as impurities is introduced from a warm end of a main heat exchanger and cooled, then introduced into an oxygen rectification column, and product ultra-high-purity oxygen from which the low-boiling-point components have been removed is drawn as a gas or a liquid from a lower portion of the oxygen rectification column.

An air separation device for distilling air at a low temperature, includes a high-pressure column to separate high-pressure raw material air into high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air; a low-pressure column to separate the high-pressure oxygen-enriched liquefied air into low-pressure nitrogen gas, low-pressure liquefied oxygen, and argon-enriched liquefied oxygen; an argon column to separate the argon-enriched liquefied oxygen having a pressure higher than the pressure into argon gas and medium-pressure liquefied oxygen; first and second indirect heat-exchangers; first and second gas-liquid separation chambers; a first/second passage which communicates the gas/liquid phase of the low-pressure column and the gas phase of the second gas-liquid separation chamber; and a first/second opening/closing mechanism located on the first/second passage.

A method and apparatus to obtain a compressed nitrogen product by low-temperature fractionation of air in a distillation column system. The system has a high-pressure column, a low-pressure column, a main condenser, and a low-pressure column top condenser. Bottoms liquid from the low-pressure column is evaporated in the top condenser and the gas formed is decompressed to perform work that drives a cold compressor. A gaseous first compressed nitrogen product stream from the high-pressure column is warmed in the main heat exchanger. A further gaseous nitrogen stream from the low-pressure column is compressed in the cold compressor and warmed as a second compressed nitrogen product stream in the main heat exchanger. The cold compressor overcomes a pressure differential which is at least equal to two thirds of the pressure differential between the top of the high-pressure column and the top of the low-pressure column.

A method and apparatus for producing compressed nitrogen and liquid nitrogen. A separation system has a high-pressure column, a low-pressure column with a top condenser and a main condenser. Air is compressed in an air compressor, purified, cooled in a heat exchanger and introduced into the high-pressure column. A first part of the gaseous top nitrogen from the low-pressure column becomes compressed nitrogen product. A second part of the gaseous top nitrogen is condensed in the condensing space of the top condenser and vapour is drawn off as a residual gas stream. The vapor is expanded in a first expansion machine. A second compressed nitrogen stream from the top of the high-pressure column is expanded in a second expansion machine and then drawn off as compressed nitrogen product. A part of the nitrogen condensed in the top condenser is drawn off as liquid nitrogen product.

A method for obtaining one or more air products by means of an air separation unit comprising a first booster, a second booster, a first decompression machine, and a rectification column system which has a high-pressure column operated at a first pressure level and a low-pressure column operated at a second pressure level below the first pressure level. All of the air supplied to the rectification column system is first compressed to a third pressure level, which lies at least 3 bar above the first pressure level, as a feed air quantity. A first fraction of the feed air quantity is supplied to a first booster at the third pressure level and at a temperature level of 140 to 70 C. and is compressed to a fourth pressure level using the first booster.

A method for obtaining an air product from an air separation plant having a distillation column system and a tank system. The tank system includes a first tank and a second tank. Cryogenic liquid is withdrawn from the distillation column system, stored in the tank system, and used as the air product. The cryogenic liquid is supplied to the first tank and withdrawn from the second tank during a first period, and is supplied to the second tank and withdrawn from the first tank during a second period. The tank system has a third tank to which cryogenic liquid withdrawn from the first tank and the second tank is transferred unheated. The air product is withdrawn from the third tank in liquid state, vaporized and discharged. Alternatively, the cryogenic liquid can be withdrawn from the third tank and stored in the liquid state in a fourth tank.

A nitrogen generating method for producing product nitrogen using a nitrogen generating device comprising a main heat exchanger for cooling feed air, a nitrogen rectification column into which the feed air cooled in the main heat exchanger is introduced, and a nitrogen condenser which condenses a vapour stream fed from the nitrogen rectification column and circulates the same to the nitrogen rectification column, the method including a control step for discharging liquid nitrogen condensed by the nitrogen condenser and stored in a liquid nitrogen buffer, which is provided in an upper gas phase portion of the nitrogen rectification column or separately from the nitrogen rectification column, to a rectification portion of the nitrogen rectification column in response to an increase in an amount of product nitrogen or an increase in a flow rate of the feed air.