METHOD AND APPARATUS FOR THE CRYOGENIC SEPARATION OF AIR

摘要

A method and the apparatus for the cryogenic separation of air in an air separation plant which has a main air compressor, a main heat exchanger and a distillation column system with a high-pressure column and a low-pressure column. All of the feed air is compressed in the main air compressor to a first air pressure which is at least 3 bar higher than the operating pressure of the high-pressure column. A first part of the compressed total air flow, as first air flow at the first air pressure, is cooled and liquefied or pseudo-liquefied in the main heat exchanger, then expanded and introduced into the distillation column system. A second part of the compressed total air flow, as second air flow, is post-compressed in an air post-compressor to a second air pressure and at least part is further compressed in a first turbine-driven post-compressor to a third air pressure.

主权项

1. A method for the cryogenic separation of air in an air separation plant which has a main air compressor, a main heat exchanger and a distillation column system with a high-pressure column and a low-pressure column, wherein
all of the feed air is compressed in the main air compressor to a first air pressure which is at least 3 bar higher than the operating pressure of the high-pressure column, in order to form a compressed total air flow, a first part of the compressed total air flow, as first air flow at the first air pressure, is cooled and liquefied or pseudo-liquefied in the main heat exchanger, then expanded and introduced into the distillation column system, —a second part of the compressed total air flow, as second air flow, is post-compressed in an air post-compressor to a second air pressure which is higher than the first air pressure, and at least a first part of the second air flow is further compressed in a post-compression system to a third air pressure which is higher than the second air pressure, wherein the post-compression system has at least one first turbine-driven post-compressor, a first partial flow of the second air flow as third air flow at a first turbine inlet pressure is introduced into a first turbine, where it is expanded, performing work, and is then introduced into the distillation column system, wherein the first turbine inlet pressure is greater than the first air pressure but is not greater than the third air pressure, and the first turbine drives the first turbine-driven post-compressor, a second partial flow of the second air flow as fourth air flow, at a pressure which is greater than the first air pressure but not greater than the third air pressure, is cooled and liquefied or pseudo-liquefied in the main heat exchanger, then expanded and introduced into the distillation column system, —at least occasionally at least one liquid product is obtained in the distillation column system and is drawn off from the air separation plant, a first product flow is drawn off in liquid form from the distillation column system, is raised in the liquid state to a first elevated product pressure, is evaporated or pseudo-evaporated and heated in the main heat exchanger and the heated first product flow is drawn off from the air separation plant as first compressed gas product,characterized in that
at least occasionally
a third partial flow of the second air flow as sixth air flow in the main heat exchanger is cooled to a first intermediate temperature, is further compressed in a cold compressor to a fourth air pressure which is higher than the third air pressure andthe further compressed sixth air flow at the fourth air pressure is cooled and liquefied or pseudo-liquefied in the main heat exchanger, then expanded and introduced into the distillation column system, in a first mode of operation a first total quantity of liquid products is drawn off from the air separation plant, in a second mode of operation a second total quantity of liquid products, which is less than the first total quantity, is drawn off from the air separation plant, and in that in the first mode of operation the quantity of air which is guided as sixth air flow through the cold compressor is less than in the second mode of operation.