FIELD: liquefaction or curing of gases.
SUBSTANCE: invention relates to a method and device for low-temperature air separation. Method and apparatus are used in an air separation unit, which comprises a main air compressor, a main heat exchanger and a distillation column system with a high pressure column and a low pressure column. Method is implemented as follows: the supplied air is compressed in the main air compressor to the first pressure, which is higher than the operating pressure of the high-pressure column, first part of the compressed air stream as the first air stream at the first pressure is cooled in the main heat exchanger and liquefied or pseudo-liquefied, then expanded and introduced into the system of distillation columns, the second part of the compressed air flow as the second air flow is further compressed in an additional air compressor to a second pressure that is higher than the first pressure, and at least partially further compressed in the first turbine driven additional compressor to a third pressure that is higher than the second pressure, the first partial flow of the second air flow as the third air flow at the first inlet pressure of the turbine is introduced into the first turbine, where it expands to do the work and then is introduced into the distillation column system, with the first turbine inlet pressure greater than the first pressure, but not greater than the third pressure, and the first turbine drives the first additional turbine driven by the turbine, the second partial flow of the second air flow as the fourth air flow under pressure, which is greater than the first pressure, but not greater than the third pressure, is cooled in the main heat exchanger and liquefied or pseudo-liquefied, then it expands and is introduced into the distillation column system, the third partial stream of the second air stream as the sixth air stream is cooled in the main heat exchanger to the first intermediate temperature, additionally compressed in a cold compressor to a fourth air pressure that is higher than the third pressure, and the additionally compressed sixth air stream is cooled at the fourth air pressure in the main heat exchanger, liquefied or pseudo-liquefied, then it expands and is introduced into the system of distillation columns, while in the system of distillation columns a liquid product is extracted and removed from the air separation unit, first product stream in liquid form is removed from the system of distillation columns; in the liquid state it is brought to the first increased product pressure; in the main heat exchanger it evaporates or pseudo-evaporates and heats up and then extracted as the first compressed gaseous product, and in the first operating mode, the first full amount of liquid products is removed from the air separation unit, in the second operating mode, the second full amount of liquid products is removed from the air separation unit, which is smaller than the first full quantity, and in the first operating mode, the amount of air that is sent as the sixth air flow through the cold compressor is less than in the second operating mode.
EFFECT: invention provides the ability to work with a highly variable fraction of a liquid product, id est flows that leave the air separation unit in liquid form, and effective air separation.
15 cl, 9 dwg, 1 tbl
