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US 11,988,446 B2Granted
Method and apparatus for producing high-purity nitrogen and low-purity oxygen
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorsAlain Briglia, Huali Xie, Yongshun Zhang
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Abstract
A method and apparatus for producing high-purity nitrogen and low-purity oxygen using three-column rectification are provided, in which: nitrogen and oxygen undergo rectification in different columns, with high-purity nitrogen and low-purity oxygen being separated out of air simultaneously, thereby overcoming the shortcomings of conventional low-purity oxygen production equipment, and also reducing equipment investment, lowering energy consumption, increasing product added value, and realizing a circular economy effect.
Claims10
A method for producing high-purity nitrogen and low-purity oxygen, the method comprising the steps of:
- cooling feedstock air in a main heat exchanger and then introducing the feedstock air into a rectification system for nitrogen/oxygen separation, the rectification system having at least a high-pressure column and a low-pressure column;
- collecting an oxygen stream from a lower region of the low-pressure column, heating the oxygen stream in the main heat exchanger, and then obtaining the oxygen stream as a pressurized oxygen product;
- collecting a first nitrogen stream from a top region of the high-pressure column, heating the first nitrogen stream in the main heat exchanger, and obtaining the first nitrogen stream as a pressurized nitrogen product;
- collecting waste nitrogen in a gaseous state from a top region of the low-pressure column and heating the waste nitrogen in the main heat exchanger, before using as regenerated gas or venting;
- and
- providing a medium-pressure column between the high-pressure column and low-pressure column, with an operating pressure of the medium-pressure column being between that of the high-pressure column and that of the low-pressure column,
- wherein the lower region of the low-pressure column has a low-pressure condensing evaporator,
- wherein a lower region of the medium-pressure column has a medium-pressure condensing evaporator,
- wherein the rectification system comprises a high-pressure subcooler and a low-pressure subcooler,
- wherein the feedstock air passing through a first pressurizer is pressurized to a first pressure air, and then a first portion of the first pressure air is cooled in the main heat exchanger and led into a lower region of the high-pressure column, and a second portion of the first pressure air is pressurized in a second pressurizer to a second pressure air;
- wherein a first portion of the second pressure air is cooled in the main heat exchanger and collected from a middle position of the main heat exchanger, and then passes through an expander to obtain a third pressure air which is led into the lower region of the medium-pressure column, and a second portion of the second pressure air is liquefied or undergoes pseudo-liquefaction in the main heat exchanger,
- wherein one portion of the second portion of the second pressure air which has been liquefied or has undergone pseudo-liquefaction is led into the lower region of the high-pressure column,
- wherein another portion of the second portion of the second pressure air which has been liquefied or has undergone pseudo-liquefaction passes through the high-pressure subcooler and is led into a middle region of the low-pressure column,
- wherein high-pressure oxygen-rich liquid air is collected from the bottom of the high-pressure column, passes through the low-pressure subcooler and is then throttled and led into a middle region of the medium-pressure column;
- medium-pressure oxygen-rich liquid air is collected from the medium-pressure condensing evaporator, passes through the low-pressure subcooler and is then throttled and led into the lower region of the low-pressure column;
- lean liquid nitrogen is collected from the middle region of the medium-pressure column, passes through the low-pressure subcooler and is then throttled and led into an upper region of the low-pressure column, and
- wherein a second nitrogen stream is collected from an upper region of the medium-pressure column, undergoes a pressure increase in the liquid state, passes through the high-pressure subcooler and is led into the top region of the high-pressure column.
14 more elements
An apparatus for producing high-purity nitrogen and low-purity oxygen, the apparatus having a rectification system for nitrogen/oxygen separation, and the rectification system having at least a high-pressure column and a low-pressure column, the apparatus further comprising:
- a. a main heat exchanger configured to cool compressed and purified feedstock air;
- b. a first component configured to collect an oxygen stream from a lower region of the low-pressure column, the oxygen stream being heated in the main heat exchanger and obtained as a pressurized oxygen product;
- c. a second component configured to collect a first nitrogen stream from a top region of the high-pressure column, the first nitrogen stream being heated in the main heat exchanger and obtained as a pressurized nitrogen product;
- d. a third component configured to collect a waste nitrogen in the gaseous state from a top region of the low-pressure column, the waste nitrogen being heated in the main heat exchanger, and serving as regenerated gas or being vented;
- e. a medium-pressure column, arranged between the high-pressure column and the low-pressure column;
- f. a low-pressure condensing evaporator, arranged at the lower region of the low-pressure column;
- g. a medium-pressure condensing evaporator, arranged at a lower region of the medium-pressure column;
- h. a first pressurizer configured to pressurize the feedstock air to a first pressure;
- i. a fourth component configured to introduce a first portion of the first pressure air into a lower region of the high-pressure column after being cooled in the main heat exchanger;
- j. a second pressurizer configured to pressurize a second portion of the first pressure air to a second pressure to form a second pressure air;
- k. an expander configured to expand a first portion of the second pressure air to a third pressure to form a third pressure air;
- l. a fifth component configured to introduce the third pressure air into the lower region of the medium-pressure column;
- m. a sixth component configured to subject a second portion of the second pressure air to liquefaction or pseudo-liquefaction;
- n. a seventh component configured to introduce one portion of the second portion of the second pressure air which has been liquefied or has undergone pseudo-liquefaction into the lower region of the high-pressure column;
- o. an eighth component configured to introduce another portion of the second portion of the second pressure air which has been liquefied or has undergone pseudo-liquefaction through a high-pressure subcooler and into a middle region of the low-pressure column;
- p. a low-pressure subcooler configured to subcool a high-pressure oxygen-rich liquid air, medium-pressure oxygen-rich liquid air and lean liquid nitrogen;
- q. a high-pressure subcooler configured to subcool the another portion of the second portion of the second pressure air which has been liquefied or has undergone pseudo-liquefaction;
- r. a ninth component configured to collect the high-pressure oxygen-rich liquid air from the bottom of the high-pressure column, passing the high-pressure oxygen-rich liquid air through the low-pressure subcooler, throttling the high-pressure oxygen-rich liquid air and then leading the high-pressure oxygen-rich liquid air into a middle region of the medium-pressure column;
- s. a tenth component configured to collect the medium-pressure oxygen-rich liquid air from the medium-pressure condensing evaporator, passing the medium-pressure oxygen-rich liquid air through the low-pressure subcooler, throttling the medium-pressure oxygen-rich liquid air and the leading the medium-pressure oxygen-rich liquid air into the lower region of the low-pressure column;
- t. an eleventh component configured to collect the lean liquid nitrogen from the middle region of the medium-pressure column, passing the lean liquid nitrogen through the low-pressure subcooler, throttling the lean liquid nitrogen and the leading the lean liquid nitrogen into an upper region of the low-pressure column;
- and
- u. a twelfth component configured to collect a second nitrogen stream from an upper region of the medium-pressure column, subjecting the second nitrogen stream to a pressure increase in the liquid state, passing the second nitrogen stream through the high-pressure subcooler and then leading the second nitrogen stream into the top region of the high-pressure column.
19 more elements
Dependencies are inferred from the claim text.