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 Cryogenic liquid is withdrawn from the distillation column system, stored in the tank system, and used as the air product. The cryogenic liquid is supplied to the first tank and withdrawn from the second tank during a first period, and is supplied to the second tank and withdrawn from the first tank during a second period. The tank system has a third tank to which cryogenic liquid withdrawn from the first tank and the second tank is transferred unheated. The air product is withdrawn from the third tank in liquid state, vaporized and discharged. Alternatively, the cryogenic liquid can be withdrawn from the third tank and stored in the liquid state in a fourth tank.

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.

One object of the present invention is to provide a compact multistage liquid storage-type condenser-evaporator capable of producing two kinds of gases having different compositions without increasing power, and a nitrogen production device using the multistage liquid storage-type condenser-evaporator without increasing the power for producing nitrogen, and the present invention provides a multistage liquid storage-type condenser-evaporator including a bottom liquid storage section which is configured to store the liquid supplied into the bottom evaporation passage without circulating, and a fluid collection section which is configured to collect the fluid which flows out from the bottom evaporation passage and discharge to the outside without returning into the bottom liquid storage section.

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 Cryogenic liquid is withdrawn from the distillation column system, stored in the tank system, and used as the air product.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 method for providing a nitrogen product, an oxygen product and a hydrogen product, wherein an air separation installation is used which is designed for the low-temperature separation of feed air and which has a rectification column system, the rectification column system comprising an air-fed rectification column and a main heat exchanger. The provision of the nitrogen product comprises, in particular, subjecting feed air to low-temperature rectification using the air-fed rectification column such that a tops gas is obtained, and using part of the tops gas as the nitrogen product. The provision of the oxygen product and the hydrogen product comprises subjecting water to water electrolysis in an electrolyzer, such that a water-containing oxygen stream and a hydrogen stream are obtained, the water-containing oxygen stream or part thereof being subjected, at least in one operating phase, to drying and, in an unmixed state, to liquefaction in the air separation installation.