US 5,669,237 A · Method and apparatus for the low-temperature fractionation of air · patentgrep

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Abstract

For the method, air (103, 104) is fractionated in a medium-pressure column (6) and a low-pressure column (5). The sump heating (3) of the low-pressure column (5) is carried out with a second airflow (204), which is liquefied at the same time. An intermediate fraction (18) is taken from the low-pressure column (5) and evaporated in the head condenser (10) of the medium-pressure column (6). The thereby resulting vapor (19) is returned to the low-pressure column. In the event that impure oxygen is obtained, the second airflow (203, 204) is recompressed (202) upstream from the sump heating (3), external energy being supplied, to a pressure above that of the medium-pressure column, the pressure being relieved downstream from the sump heating (3) in a first pressure relief valve (208) to the pressure of the medium-pressure column (6). If pure oxygen is recovered, the sump heating of the low-pressure column is operated with an airflow, which at the same time is condensed at least partially and is under a pressure, which is less than the pressure of the medium-pressure column. If oxygen of high and low purity is to be recovered, a portion of the evaporated first intermediate fraction and/or a fraction obtained below the second intermediate site are recovered from the low-pressure column as oxygen product of lower purity.

Claims27

Dependent claims

A method for the low temperature fractionation of air, comprising:

forming a first airflow and a second airflow,
passing the first airflow into a medium-pressure column, which is operated at above atmospheric pressure and in which an oxygen-enriched sump liquid and a first nitrogen-rich fraction are obtained,
passing the sump liquid at a first intermediate site into a low-pressure column, which is operated under a pressure lower than that of the medium-pressure column,
condensing the first nitrogen-rich fraction at least partially by indirect heat exchange, a nitrogen-rich liquid being produced,
using a first portion of the nitrogen-rich liquid as backflow in the medium-pressure column,
using a second portion of the nitrogen-rich liquid as backflow in the low-pressure column,
obtaining a second nitrogen-rich fraction at the head of the low-pressure column and obtaining an oxygen-rich liquid in the sump of the low-pressure column,
evaporating the oxygen-rich liquid at least partially by indirect heat exchange against the second airflow in an indirect heat exchanger,
using at least a portion of the evaporated, oxygen-rich liquid as rising vapor in the low-pressure column,
drawing off a different portion of the evaporated, oxygen-rich liquid and/or a portion of the oxygen-rich liquid as oxygen product(s),
evaporating a first liquid intermediate fraction, which is obtained in the low-pressure column at a second intermediate site, at least partially by the indirect heat exchange for condensing the first nitrogen-rich fraction,
and using at least a portion of the evaporated first intermediate fraction as rising vapor in the low-pressure column,
wherein the second airflow is under a pressure during the heat exchange in the indirect heat exchanger which is different than the pressure of the medium pressure column, and
wherein the second airflow is under a pressure during the heat exchange in the indirect heat exchanger which is less than the pressure of the medium pressure column.

11 more elements

A method for the low temperature fractionation of air, comprising:

forming a first airflow and a second airflow,
passing the first airflow into a medium-pressure column, which is operated at above atmospheric pressure and in which an oxygen-enriched sump liquid and a first nitrogen-rich fraction are obtained,
passing the sump liquid at a first intermediate site into a low-pressure column, which is operated under a pressure lower than that of the medium-pressure column,
condensing the first nitrogen-rich fraction at least partially by indirect heat exchange, a nitrogen-rich liquid being produced,
using a first portion of the nitrogen-rich liquid as backflow in the medium-pressure column,
using a second portion of the nitrogen-rich liquid as backflow in the low-pressure column,
obtaining a second nitrogen-rich fraction at the head of the low-pressure column and obtaining an oxygen-rich liquid in the sump of the low-pressure column,
evaporating the oxygen-rich liquid at least partially by indirect heat exchange against the second airflow in an indirect heat exchanger,
using at least a portion of the evaporated, oxygen-rich liquid as rising vapor in the low-pressure column,
drawing off a different portion of the evaporated, oxygen-rich liquid and/or a portion of the oxygen-rich liquid as oxygen product(s),
evaporating a first liquid intermediate fraction, which is obtained in the low-pressure column at a second intermediate site, at least partially by the indirect heat exchange for condensing the first nitrogen-rich fraction,
and using at least a portion of the evaporated first intermediate fraction as rising vapor in the low-pressure column,
wherein the second airflow is under a pressure during the heat exchange in the indirect heat exchanger which is different than the pressure of the medium pressure column, and
wherein
a portion of the evaporated first intermediate fraction and/or
a fraction from the low-pressure column, obtained below the second intermediate site is/are obtained as a further oxygen product, the purity of which is lower than that of the oxygen product obtained in the form of an evaporated, oxygen-rich liquid and/or in the form of an oxygen-rich liquid from the sump of the low-pressure column.

13 more elements

A method for the low temperature fractionation of air, comprising:

forming a first airflow and a second airflow,
passing the first airflow into a medium-pressure column, which is operated at above atmospheric pressure and in which an oxygen-enriched sump liquid and a first nitrogen-rich fraction are obtained,
passing the sump liquid at a first intermediate site into a low-pressure column, which is operated under a pressure lower than that of the medium-pressure column,
condensing the first nitrogen-rich fraction at least partially by indirect heat exchange, a nitrogen-rich liquid being produced,
using a first portion of the nitrogen-rich liquid as backflow in the medium pressure-column,
using a second portion of the nitrogen-rich liquid as backflow in the low-pressure column,
obtaining a second nitrogen-rich fraction at the head of the low-pressure column and obtaining an oxygen-rich liquid in the sump of the low-pressure column,
evaporating the oxygen-rich liquid at least partially by indirect heat exchange against the second airflow in an indirect heat exchanger,
using at least a portion of the evaporated, oxygen-rich liquid as rising vapor in the low-pressure column,
drawing off a different portion of the evaporated, oxygen-rich liquid and/or a portion of the oxygen-rich liquid as oxygen product(s),
evaporating a first liquid intermediate fraction, which is obtained in the low-pressure column at a second intermediate site, at least partially by the indirect heat exchange for condensing the first nitrogen-rich fraction,
and using at least a portion of the vaporated first intermediate fraction as rising vapor in the low-pressure column,
wherein the second airflow is under a pressure during the heat exchange in the direct heat exchanger which is different than the pressure of the medium pressure column, and
wherein the indirect heat exchange between the first liquid intermediate fraction and the first nitrogen-rich fraction is carried out in a heat exchanger which is disposed outside of the low-pressure column.

11 more elements

A method for the low temperature fractionation of air, comprising:

forming a first airflow and a second airflow,
passing the first airflow into a medium-pressure column, which is operated at above atmospheric pressure and in which an oxygen-enriched sump liquid and a first nitrogen-rich fraction are obtained,
passing the sump liquid at a first intermediate site into a low-pressure column, which is operated under a pressure lower than that of the medium-pressure column,
condensing the first nitrogen-rich fraction at least partially by indirect heat exchange, a nitrogen-rich liquid being produced,
using a first portion of the nitrogen-rich liquid as backflow in the medium-pressure column,
using a second portion of the nitrogen-rich liquid as backflow in the low-pressure column,
obtaining a second nitrogen-rich fraction at the head of the low-pressure column and obtaining an oxygen-rich liquid in the sump of the low-pressure column,
evaporating the oxygen-rich liquid at least partially by indirect heat exchange against the second airflow in an indirect heat exchanger,
using at least a portion of the evaporated, oxygen-rich liquid as rising vapor in the low-pressure column,
drawing off a different portion of the evaporated, oxygen-rich liquid and/or a portion of the oxygen-rich liquid as oxygen product(s),
evaporating a first liquid intermediate fraction, which is obtained in the low-pressure column at a second intermediate site, at least partially by the indirect heat exchange for condensing the first nitrogen-rich fraction,
and using at least a portion of the evaporated first intermediate fraction as rising vapor in the low-pressure column,
wherein the second airflow is under a pressure during the heat exchange in the indirect heat exchanger which is different than the pressure of the medium pressure column, and
wherein a second liquid intermediate fraction is removed from the low pressure column at a third intermediate site and evaporated at least partially in indirect heat exchange, and wherein the evaporated second intermediate fraction is returned at least partially to the low-pressure column.

11 more elements

A method for the low temperature fractionation of air, comprising:

forming a first airflow and a second airflow,
passing the first airflow into a medium-pressure column, which is operated at above atmospheric pressure and in which an oxygen-enriched sump liquid and a first nitrogen-rich fraction are obtained,
passing the sump liquid at a first intemediate site into a low-pressure column, which is operated under a pressure lower than that of the medium-pressure column,
condensing the first nitrogen-rich fraction at least partially by indirect heat exchange, a nitrogen-rich liquid being produced,
using a first portion of the nitrogen-rich liquid as backflow in the medium-pressure column,
using a second portion of the nitrogen-rich liquid as backflow in the low-pressure column,
obtaining a second nitrogen-rich fraction at the head of the low-pressure column and obtaining an oxygen-rich liquid in the sump of the low-pressure column,
evaporating the oxygen-rich liquid at least partially by indirect heat exchange against the second airflow in an indirect heat exchanger,
using at least a portion of the evaporated, oxygen-rich liquid as rising vapor in the low-pressure column,
drawing off a different portion of the evaporated, oxygen-rich liquid and/or a portion of the oxygen-rich liquid as oxygen product(s),
evaporating a first liquid intermediate fraction, which is obtained in the low-pressure column at a second intermediate site, at least partially by the indirect heat exchange for condensing the first nitrogen-rich fraction,
and using at least a portion of the evaporated first intermediate fraction as rising vapor in the low-pressure column,
wherein
a portion of the evaporated first intermediate fraction and/or
a fraction from the low-pressure column, obtained below the second intermediate site is/are obtained as a further oxygen product, the purity of which is lower than that of the oxygen product obtained in the form of an evaporated, oxygen-rich liquid and/or in the form of an oxygen-rich liquid from the sump of the low-pressure column, and
wherein the indirect heat exchange between the first liquid intermediate fraction and the first nitrogen-rich fraction is carried out in a heat exchanger which is disposed outside of the low-pressure column.

13 more elements

A method for the low temperature fractionation of air, comprising:

forming a first airflow and a second airflow,
passing the first airflow into a medium-pressure column, which is operated at above atmospheric pressure and in which an oxygen-enriched sump liquid and a first nitrogen-rich fraction are obtained,
passing the sump liquid at a first intermediate site into a low-pressure column, which is operated under a pressure lower than that of the medium-pressure column,
condensing the first nitrogen-rich fraction at least partially by indirect heat exchange, a nitrogen-rich liquid being produced,
using a first portion of the nitrogen-rich liquid as backflow in the medium-pressure column,
using a second portion of the nitrogen-rich liquid as backflow in the low-pressure column,
obtaining a second nitrogen-rich fraction at the head of the low-pressure column and obtaining an oxygen-rich liquid in the sump of the low-pressure column,
evaporating the oxygen-rich liquid at least partially by indirect heat exchange against the second airflow in an indirect heat exchanger,
using at least a portion of the evaporated, oxygen-rich liquid as rising vapor in the low-pressure column,
drawing off a different portion of the evaporated, oxygen-rich liquid and/or a portion of the oxygen-rich liquid as oxygen product(s),
evaporating a first liquid intermediate fraction, which is obtained in the low-pressure column at a second intermediate site, at least partially by the indirect heat exchange for condensing the first nitrogen-rich fraction,
and using at least a portion of the evaporated first intermediate fraction as rising vapor in the low-pressure column,
wherein
a portion of the evaporat and first intermediate fraction and/or
a fraction from the low-pressure column, obtained below the second intermediate site is/are obtained as a further oxygen product, the purity of which is lower than that of the oxygen product obtained in the form of an evaporated, oxygen-rich liquid and/or in the form of an oxygen-rich liquid from the sump of the low-pressure column, and
wherein a second liquid intermediate fraction is removed from the low pressure column at a third intermediate site and evaporated at least partially in indirect heat exchange, and wherein the evaporated second intermediate fraction is returned at least partially to the low-pressure column.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/614,974Filed 11 Mar 1996
Priority: DE 195 08 759.310 Mar 1995
Granted: 23 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification24 codes

F25J 3/04709
Producing crude argon in a crude argon column: as an auxiliary column system in at least a dual pressure main column system
F25J 3/04018
By compression of warm gaseous streams; details of intake or interstage cooling: of main feed air
F25J 3/04139
Arrangements of compressors and /or their drivers: combination of different types of drivers mechanically coupled to the same compressor, possibly…
F25J 3/04157
Purification and cooling of the feed air; recuperative heat-exchange with product streams: afterstage cooling and so-called "pre-cooling" of the…

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