Method and device for generating gaseous compressed nitrogen

Patent metadata

Field	Value
Publication number	US-2016003531-A1
Application number	US-201414769465-A
Country	US
Kind code	A1
Filing date	Mar 18, 2014
Priority date	Mar 19, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

Method and device for generating gaseous compressed nitrogen by the low-temperature separation of air in a distillation column system, having a pre-column, a high-pressure column and a low-pressure column. The feed air is compressed, purified in a purification apparatus and cooled. A first sub-flow of the cooled feed air is introduced in a predominantly liquid state into the distillation column system. A gaseous fraction from the pre-column in introduced into the liquefaction chamber of a pre-column head condenser with liquid formed therein fed as reflux into the pre-column. A first gaseous nitrogen product fraction is drawn from the high-pressure column, heated, and obtained as first gaseous compressed nitrogen product. At least a part of the second sub-flow is introduced into the evaporation chamber of the pre-column head condenser. A third sub-flow of the cooled feed air is expanded to perform work and subsequently introduced into the liquefaction chamber.

First claim

1 . A method for generating gaseous compressed nitrogen by low-temperature separation of air in a distillation column system, which has a pre-column, a high-pressure column and a low-pressure column, and in which
A the input air that is encompassed within a quantity of input air is compressed in a main air compressor, the compressed input air is cleaned in a cleaning device, the cleaned input air is cooled in a main heat exchanger, a first partial current of the cooled input air is fed in gaseous form into the pre-column, a second partial current of the cooled input air is fed in a predominantly liquid state into the distillation column system, the pre-column has a pre-column head condenser that takes the form of a condenser/evaporator having a liquefaction chamber and an evaporation chamber, a gaseous fraction from the upper region of the pre-column is fed into the liquefaction chamber of the head condenser and in that at least part of the liquid that is formed in the liquefaction chamber is returned to the pre-column, the low-pressure column has a low-pressure column sump evaporator that takes the form of a condenser/evaporator having a liquefaction chamber and an evaporation chamber, a first nitrogen product fraction is drawn off from the high-pressure column in gaseous form, is warmed in the main heat exchanger and is obtained as a first gaseous compressed nitrogen product, at least a first part of the second partial current is fed into the evaporation chamber of the pre-column head condenser, the pressure of a third partial current of the cooled input air is let down such that work is performed, the pressure of the third partial current is higher at the exit from letting down the pressure such that work is performed than the operating pressure of the low-pressure column,
characterized in that
the third partial current that is let down such that work is performed is fed into the liquefaction chamber of the low-pressure column sump evaporator and is at least partly liquefied there,
at least part of the liquefied third partial current is fed into the low-pressure column,
the low-pressure column moreover has an intermediate evaporator that takes the form of a condenser/evaporator having a Liquefaction chamber and an evaporation chamber,
at least part of an intermediate liquid of the low-pressure column is evaporated in the evaporation chamber of the intermediate evaporator,
at least part of a gaseous head fraction from the high-pressure column is liquefied in the liquefaction chamber of the intermediate evaporator, and at least part of the liquid obtained in this way is returned to the high-pressure column, and
more than 35 mol %, in particular more than 45 mol % of the input air quantity, in the form of the first nitrogen product fraction, which is drawn of in gaseous form from the high-pressure column, is warmed in the main heat exchanger and is obtained as a first gaseous compressed nitrogen product.

2 . The method as claimed in claim 1 , characterized in that a second gaseous nitrogen product fraction is drawn off from the pre-column in gaseous form, warmed in the main heat exchanger and obtained as to second gaseous compressed product.

3 . The method as claimed in claim 1 , characterized in that less than 30 mol % of the input air quantity is fed in the liquid state into the distillation column system.

4 . The method as claimed in claim 1 , characterized in that the total quantity of oxygen-enriched currents that are fed in the liquid state from the pre-column and the evaporation chamber of the pre-column head condenser into the high-pressure column and the low-pressure column is less 14% than the input air quantity.

5 . The method as claimed in claim 1 , characterized in that
the second partial current is compressed before being cooled in the main heat exchanger to a high pressure that is higher than the operating pressure of the pre-column, and is liquefied or pseudo-liquefied in the main heat exchanger, and in that a liquid current, in particular a liquid oxygen current, is removed from the distillation column system, brought to an elevated pressure in the liquid state, evaporated or pseudo-evaporated in the main heat exchanger and finally obtained as a gaseous compressed product.

6 . The method as claimed in claim 1 , characterized in that a gaseous fraction from the evaporation chamber of the pre-column head condenser is fed, as a gaseous input current, into the high-pressure column, in particular as a single gaseous input current of the high-pressure column.

7 . The method as claimed in claim 1 , characterized in that at least some of the sump liquid of the pre-column is fed into the evaporation chamber of the pre-column head condenser.

8 . The method as claimed in claim 1 , characterized in that the third partial current is post-compressed before being cooled in the main heat exchanger.

9 . The method as claimed in claim 1 , characterized in that the pressure of the third partial current is lower at the exit from letting down the pressure such that work is performed than the operating pressure of the high-pressure column.

10 . A device for generating gaseous compressed nitrogen by low-temperature separation of air, having a distillation column system, which has a pre-column, a high-pressure column and a low-pressure column, and having
a main air compressor for compressing all the input air that is encompassed within a quantity of input air, a cleaning device for cleaning the compressed input air, a main heat exchanger for cooling the cleaned input air, apparatus for feeding a first partial current of the cooled input air in the gaseous state into the pre-column, and having apparatus for feeding a second partial current of the cooled input air in a predominantly liquid state into the distillation column system, wherein the pre-column has a pre-column head condenser that takes the form of a condenser/evaporator having a liquefaction chamber and an evaporation chamber, having apparatus for feeding a gaseous fraction from the upper region of the pre-column into the liquefaction chamber of the head condenser, apparatus for returning liquid that is formed in the liquefaction chamber to the pre-column, wherein the low-pressure column has a low-pressure column sump evaporator that takes the form of a condenser/evaporator having a liquefaction chamber and an evaporation chamber, apparatus for drawing off a first nitrogen product fraction from the high-pressure column, for warming the first nitrogen product fraction in the main heat exchanger and for obtaining the warmed first nitrogen product fraction as a first gaseous compressed nitrogen product, wherein the apparatus for drawing off a first nitrogen product fraction from the high-pressure column is constructed for the gaseous removal of the first nitrogen product fraction from the high-pressure column, apparatus for feeding at least a first part of the second partial current into the evaporation chamber of the pre-column head condenser, a let-down machine for letting down the pressure of a third partial current of the cooled input air such that work is performed, and having apparatus for feeding the third partial current that has been let down such that work is performed into the liquefaction chamber of the low-pressure column sump evaporator,
characterized by
apparatus for feeding the liquefied third partial current from the liquefaction chamber of the low-pressure column sump evaporator into the low-pressure column,
an intermediate evaporator of the low-pressure column that takes the form of a condenser/evaporator having a liquefaction chamber and an evaporation chamber,
apparatus for feeding a

Assignees

• Linde Ag

Inventors

• Goloubev Dimitri

Classifications

• F25J3/0486

  of vaporisers for oxygen enriched liquids, e.g. purging of liquids · CPC title

• F25J3/04084

  of nitrogen · CPC title

• F25J3/04175

  at a pressure of substantially more than the highest pressure column · CPC title

• F25J3/04303

  Lachmann expansion, i.e. expanded into oxygen producing or low pressure column · CPC title

• F25J3/0257 Primary

  separation of nitrogen (from air F25J3/04, production of nitrogen in general C01B21/00) · CPC title