JPH10311673A - Air liquefaction/separation method and apparatus for producing high purity nitrogen and coarse neon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect and produce coarse neon being a raw material of neon gas having high surplus value with an air liquefaction/separation apparatus simultaneously with ultrahigh purity nitrogen gas. SOLUTION: Compressed raw material air, from which water and carbon dioxide is removed and which is cooled up to a substantially boiling point, is introduced from a pipe line 1 to a lower part of a single rectifying column 2 on an upper part of which there is provided a rectifier part 4 for condensing a low boiling point component such as hydrogen. The air is rectified in the rectifying column 2, and liquefied air is supplied from the bottom of the rectifying column 2 to a liquefied air reservoir 7 located at the top of the rectifying column 2. Gas from an upper part of the rectifier part 4 of the rectifying column 2, which gas is introduced into a condensation evaporator 8 through the pipe line 9, is cooled and liquefied. The liquefied fluid is returned through a pipe line 10 as a reflux fluid to the upper part of the rectifying column 2, and high purity liquefied nitrogen below the rectifier part 4 is fed to the condensation evaporator 8 and is vaporized using cold for collection as high purity nitrogen gas, and a pipe line 15 is divided from the pipe line 10 for the reflux fluid, from which line 15 non-condensed gas is collected as coarse neon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides a method for producing high purity nitrogen and crude neon having a low content of low boiling components such as hydrogen.
The present invention relates to an air liquefaction separation method and apparatus particularly desired in the semiconductor industry where high purity nitrogen is required and neon demand is expected.

[0002]

2. Description of the Related Art As a method and an apparatus for industrially producing nitrogen, there is a so-called air in which air is used as a raw material, which is liquefied through steps of compression, purification and cooling, and its components are rectified and separated by a difference in boiling point. A liquefaction separation method is employed. Therefore, as a conventional method for exclusively collecting nitrogen gas by this rectification, an apparatus using a single rectification column will be described as an example.

FIG. 5 shows an example of a system diagram of a single rectification column used in a conventional air liquefaction / separation apparatus. The compressed raw material air from which dust, carbon dioxide and moisture have been removed is recovered from a single rectification column 52. The gas is cooled by cold such as a gas to reach a substantially boiling point temperature, and is introduced into a lower portion of the single rectification column 52 through a pipe 51. Then, the rectification plate 5
The rectification is performed by contact with the reflux liquid flowing down 3, and nitrogen gas is rectified at the upper part of the single rectification column 52 and liquefied air rich in oxygen is rectified at the lower part. Among them, the nitrogen gas is led out through a pipe 54 as product nitrogen gas, and a part of the nitrogen gas is condensed through a pipe 55 into a liquefied air reservoir 56 partitioned at the top of the single-column rectification column 52. Enter the evaporator 57,
The pressure is reduced from the bottom of the single-column rectification column 52 through a pipe 58 and heat exchanges with the liquefied air introduced into the liquefied air reservoir 56 to be liquefied. It is introduced as a reflux liquid. The liquefied air supplied to the liquefied air reservoir 56 is vaporized using refrigeration in order to liquefy the reflux liquid gas flowing through the condensing evaporator 57, is led out from the pipe 60 and exchanges heat with the raw material air. Is cooled and released.

However, the fact is that the product nitrogen gas led out from the pipe 54 above the single-type rectification column 52 contains a gas having a lower boiling point than nitrogen, such as hydrogen, helium, or neon. . Particularly in the semiconductor industry, ultra-high purity nitrogen gas is required for use as a carrier gas for semiconductor material gas in semiconductor manufacturing, and the presence of such active hydrogen impairs the quality of manufactured products. That was not desirable. Therefore, Japanese Patent Application Laid-Open No. 60-1421 aims to collect high-purity nitrogen gas in which the harmful hydrogen content in the product nitrogen gas is made as small as possible.
No. 83 has proposed an air liquefaction separation method.

[0005] This method has been filed and proposed by the present applicant, and a system diagram of this single type rectification column will be described with reference to FIG. Note that the same components as those in FIG. 5 are denoted by the same reference numerals, and detailed description is omitted. That is, several stages of rectification plates 61 are installed at the upper part of the single-type rectification column 52 shown in FIG. The remaining amount is returned to the upper part of the single rectification column 52 via the pipe 55, the condensing evaporator 57, and the pipe 59 in the same manner as in FIG. The product nitrogen is supplied to a rectification plate 6 provided at a position of a rectification plate several stages below the discharge position of the discharge / recirculation gas discharge line 54 of the single-type rectification column 52.
3, high-purity liquefied nitrogen is led out, a part of which is depressurized by a pressure reducing valve 64, vaporized by a pipe 65 through a condensing evaporator 57, and collected as high-purity nitrogen gas by a pipe 66. The remainder is collected as high-purity liquefied nitrogen from line 67.

In this method, as described above, the single rectification column 5
A plurality of rectification plates 61 are provided on the upper part of 2, and rectification is performed in the rectification portion to reduce the amount of low boiling components such as hydrogen as much as possible,
It was concentrated in the upper part and retained in a gaseous state, and this was led out from the upper conduit 54 while controlling the amount of release, and used as reflux gas. As a result, in the rectifying plate several stages below the outlet line 54, the content of low-boiling components such as hydrogen is reduced, and from the line 63, high-purity liquefaction in which the amount of low-boiling components such as hydrogen is minimal Nitrogen is derived.

[0007]

However, the outlet line 54 at the top of the single-column rectification column 52 shown in FIG.
A part of the gas derived was released, and a part thereof was liquefied via the condensing evaporator 57 and returned to the upper part of the single rectification column 52 as reflux liquid. When the oxygen content in the product nitrogen derived from the line 63 is less than 0.3 ppm, the line 5
Analyzing the composition of the gas derived in 4
ppm hydrogen, 8-20 ppm helium, 40-10 ppm
It was found that the nitrogen gas contained 0 ppm neon. Further, when the composition of the uncondensed gas in the reflux liquid which is liquefied through the pipe 55 through the condenser evaporator 57 through the condenser evaporator 57 and returned to the upper part of the single rectification column 52 is analyzed, about 95 ppm of hydrogen, About 475 ppm helium,
It was found that about 1710 ppm of neon was nitrogen gas which was concentrated and contained.

However, in the prior art, the gas containing such high-value-added low-boiling-point component gas in a concentrated form has simply been released and wasted as described above. Therefore, the present invention focuses on the effective use of a more concentrated neon component without releasing it. That is, the present invention collects high-purity nitrogen in which a low-boiling component such as hydrogen is reduced to a trace amount in a single-column rectification column, and condenses and releases these harmful and unnecessary low-boiling component gases such as hydrogen as much as possible. By collecting this, crude neon, which is a raw material for neon with high added value, can be efficiently and simultaneously collected. It is another object of the present invention to provide an air liquefaction separation method and an apparatus for economically producing high-purity nitrogen and crude neon, which are particularly adapted to the semiconductor manufacturing industry requiring these high-purity nitrogen and neon.

[0009]

Means for Solving the Problems In order to solve the above problems and to achieve the object, a first aspect of the present invention is to compress raw air, remove water and carbon dioxide gas, and then cool to almost the boiling point. , Introduced into the lower portion of the single-column rectification column, liquefied air is led out from the bottom of the single-column rectification column, and the condensing evaporator is cooled by utilizing this cold. A gas having a high content is led out and condensed in the condensing evaporator, returned as a reflux liquid to the upper part of the single-column rectification column, and at least one theoretical stage below the lead-out position of the gas containing a low boiling point component such as hydrogen. High-purity liquefied nitrogen with a lower content of low-boiling components such as hydrogen is derived, vaporized through the condensation evaporator and collected as high-purity nitrogen gas, and hydrogen and the like derived from the upper part of the single-column rectification column Part of the gas containing a lot of low boiling components is separated And a method for producing high-purity nitrogen and crude neon simultaneously, wherein the crude liquefied gas is collected as crude neon of neon gas raw material. 2. The air for co-producing high purity nitrogen and crude neon according to claim 1, wherein a part of the gas containing a large amount of boiling components is branched after passing through the condensing evaporator, and uncondensed gas is collected as crude neon. The invention according to claim 3 is a liquefaction separation method, wherein a part of a gas containing a large amount of low-boiling components such as hydrogen derived from the upper part of a single rectification column is branched and collected as crude neon before being introduced into a condensation evaporator. The method according to claim 1, wherein the method is an air liquefaction separation method for producing high purity nitrogen and crude neon simultaneously. The invention according to claim 4 is that the condensing evaporator cooled by the cooling of the liquefied air is disposed in a liquefied air reservoir partitioned at the top of the single rectification tower, and the liquefied air from the bottom of the single rectification tower is liquefied air. 4. An air liquefaction separation method according to any one of claims 1 to 3, wherein the method is used to produce high purity nitrogen and crude neon together, wherein the method is used for introducing the mixture into a reservoir and utilizing the cold. The invention according to 5 is characterized in that the condensing evaporator cooled by the liquefied air by cooling is disposed independently of the single-column rectification column, and the liquefied air from the bottom of the single-column rectification column is made to conduct and the cooling is performed by utilizing the cold. An air liquefaction separation method according to any one of claims 1 to 3, characterized in that high purity nitrogen and crude neon are produced together.

[0010] Next, as an apparatus for carrying out the above air liquefaction separation method, the invention according to claim 6 is directed to a single type rectification column for introducing and liquefying and liquefying a raw material air, and a bottom portion of the single type rectification column. And a condensing evaporator cooled by utilizing the cooling of the liquefied air, and a gas containing a large amount of low-boiling components such as hydrogen is derived from the upper part of the single-column rectification column, and the single-column rectification column is passed through the condensation evaporator. A reflux liquid line to be returned to the upper part, and liquefied nitrogen having a lower content of low-boiling components such as hydrogen are derived from at least one theoretical stage below the single-column rectification column for deriving a gas containing a large amount of low-boiling components such as hydrogen. A high-purity nitrogen gas line, which is provided with a line for vaporizing the gas through the condensing evaporator and collecting it as high-purity nitrogen gas, and a crude neon sampling line branched from the reflux liquid line. An air liquefaction separator that produces both nitrogen and crude neon According to a seventh aspect of the present invention, the crude neon sampling line branched from the reflux liquid line which returns from the upper portion of the single-stage rectification column to the upper portion of the single-stage rectification column via the condensing evaporator is formed by condensation and evaporation of the reflux liquid line. An air liquefaction separation apparatus for producing both high-purity nitrogen and crude neon according to claim 6, wherein the apparatus is branched in a pipeline after the vessel is led out. The crude neon sampling line that branches off from the reflux liquid line that returns to the upper part of the single-stage rectification column from the upper part of the column via the condensing evaporator should be branched off from the reflux liquid line before the introduction of the condensing evaporator. An air liquefaction / separation apparatus according to claim 6, which produces both high-purity nitrogen and crude neon. According to a ninth aspect of the present invention, the condensing evaporator cooled by utilizing the cooling of the liquefied air from the bottom of the single rectification column is partitioned at the top of the single rectification column, and the liquefaction from the bottom of the single rectification column is performed. The air liquefaction for producing high-purity nitrogen and crude neon according to any one of claims 6 to 8, wherein the air supply pipe is disposed in a liquefied air reservoir provided therein and cooled. The invention according to claim 10 is a separation device.
The condensing evaporator cooled by utilizing the cooling of the liquefied air from the bottom of the single rectification column is connected to the liquefied air supply pipe from the bottom of the single rectification column to the condensing evaporator, and supplied by the pipe. 9. An air liquefaction / separation apparatus according to any one of claims 6 to 8, wherein the liquefied air is cooled by flowing liquefied air. In the invention according to Item 11, the single-column rectification column has at least one liquefied nitrogen between a position at which a gas containing a large amount of low-boiling components such as hydrogen is led out and a position at which liquefied nitrogen having a low content of low-boiling components such as hydrogen is led out. An air liquefaction / separation apparatus according to any one of claims 6 to 10, wherein a rectifying section comprising a theoretical stage is provided. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the air liquefaction separation method of the present invention for simultaneously producing high-purity nitrogen and crude neon will be described with reference to the drawings. FIG. 1 shows a system diagram of a single type rectification column for explaining a first embodiment of an air liquefaction / separation apparatus of the present invention. In this apparatus, the single-column rectification column 2 has the number of stages generally used (normally 60 stages).
In addition to the rectification unit 3, a plurality of rectification units 4 (1 to 10 stages) are provided in the upper part of the tower for concentrating low-boiling component gas such as hydrogen. However, the raw material air contains moisture after being compressed,
After removing carbon dioxide gas and the like, the mixture is cooled to almost the boiling point temperature (liquefaction temperature) and introduced into the lower part of the single type rectification column 2 through the pipe 1. The raw air introduced into the single-column rectification column 2 has a low-boiling point component in a gaseous form, which rises upward in the column, and is liquefied further upward and descends into a liquefied gas of each stage. It is contacted in the rectification unit 3 and rectified and separated by the difference in boiling point, and the higher the rectification unit is located, the more nitrogen components having a lower boiling point increase.
The lower the rectification section, the higher the oxygen component having a higher boiling point.

On the other hand, liquefied air having a higher oxygen content than the raw air is stored at the bottom of the single rectification column 2, and the liquefied air is expanded and decompressed by a valve 5, and is passed through a pipe 6 to the top of the single rectification column 2. Is supplied to the liquefied air reservoir 7 connected to the liquefied air reservoir 7. The liquefied air reservoir 7 is provided with a condensing evaporator 8 formed of a plurality of flow paths and configured to exchange heat with each other so as to be immersed in the stored liquefied air. The condensing evaporator 8 has a conduit 9 communicating with an upper part of the rectification section 4 having, for example, three to five stages provided for concentrating low boiling components such as hydrogen at the upper part of the single rectification column 2.
And a gas in which low-boiling components such as hydrogen are concentrated from the upper portion of the single-column rectification column 2 is liquefied through a line 9 through a condensing evaporator 8, and is liquefied through a line 10. It is returned to the upper part as reflux liquid.

The lower part of, for example, the three- to five-stage rectification section 4 provided above the single-type rectification column 2 contains the low-boiling component gas such as hydrogen concentrated by the rectification section 4. The gas rises upward to reduce these components, and high-purity liquefied nitrogen having an oxygen concentration of less than 0.3 ppm is rectified and present. Through the line 13 to the condensation evaporator 8.
Then, the cold is used for liquefaction of the reflux gas to vaporize it, and it is led out from the pipe 14 and collected as high-purity nitrogen gas in which low-boiling components such as hydrogen are reduced to an extremely small amount.

However, the gas containing a low-boiling component gas such as hydrogen extracted from the upper part of the single-stage rectification column 2 through a pipe 9 is concentrated, and the liquefied air of the single-stage rectification column 2 is condensed by a condensing evaporator 8. Line 11, valve 12, line 13 from the liquefied air in reservoir 7 and the lower part of rectification unit 4 for concentrating low boiling point such as hydrogen in single type rectification column 2.
And high-purity liquefied nitrogen introduced into the condensing evaporator 8 to liquefy most of the nitrogen having a high boiling point (boiling point: about -196 ° C. at 1 atm). However, gases such as hydrogen having a lower boiling point (boiling point: about -253 ° C at 1 atm), helium (boiling point: about -269 ° C at 1 atm), neon (boiling point: about -246 ° C at 1 atm) are not liquefied. In the state, about 475 ppm of helium, about 95 pp of hydrogen
A nitrogen gas containing a component concentrated to about 1710 ppm in neon is led out to the pipe 10 from the condensing evaporator 8, and is collected as crude neon as a neon raw material through a pipe 15 branched from the pipe 10. I do. Reference numeral 16 denotes an outlet line for oxygen-enriched air which is vaporized as a result of the liquefied air stored in the liquefied air reservoir 7 being used for liquefaction of the circulating liquid by using its cold.

The thus-collected crude neon gas containing a large amount of neon components is sent from the pipe line 15 to a concentrating means C using a decomposer for decomposing, for example, by a difference in boiling point.
It is concentrated to a nitrogen gas containing about 14% of helium, about 3% of hydrogen and about 49% of neon, and this is further reduced to 99% using a conventionally known purification means P such as adsorption separation and rectification.
Purified and collected as high purity neon as described above.

According to the present invention, as described above, a rectifying section 4 having one or more theoretical plates is provided at the upper part of the single rectifying column 2 in order to concentrate low boiling components such as hydrogen. High-purity liquefied nitrogen is led out from the lower part,
Vaporized using refrigeration at low temperatures, and collected as high-purity nitrogen gas with extremely low levels of low-boiling components such as hydrogen,
A gas used for reflux liquid is led out from above the rectification section 4 for concentrating low boiling components such as hydrogen of one or more stages provided at the upper part of the single type rectification column 2, At the time of liquefaction in order to obtain a reflux liquid which is cooled and returned to the upper part of the single-column rectification column 2, the low-boiling-point component gas which is in a gaseous state without being liquefied is concentrated to fractionate the contained gas. The low-boiling point component containing is effectively concentrated, and can be efficiently collected as crude neon as a raw material of neon. In addition, the normal operation of the conventional single rectification type nitrogen production apparatus is maintained, and it is possible to effectively co-produce these without changing or impairing the power consumption unit.

Next, a modification of the embodiment shown in FIG. 1 will be described as a second embodiment with reference to FIG. 2 which shows a system diagram of the single rectification column. The same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. The difference from the first embodiment shown in FIG. 1 is that in the first embodiment shown in FIG. 1, the crude neon sampling line is branched from the line 10 after the condensing evaporator 8 is led out from the line 15. In contrast, in the second embodiment shown in FIG. 2, a low-boiling-point component gas such as hydrogen at the upper part of the single-column rectification column 2, which is introduced into the condensing evaporator 8 for liquefaction for a reflux liquid, is concentrated and contained. Before the nitrogen gas to be introduced into the condensing evaporator 8, crude neon is collected in a pipe 25 branched from the pipe 9.

According to this method, a rectifying section 4 provided at the upper part of the single-type rectifying column 2 for concentrating low-boiling components such as hydrogen.
If one or more stages (for example, 6 to 9 stages) are provided in the first embodiment of FIG. 1, nitrogen gas in which low-boiling components such as hydrogen are more concentrated can be obtained as crude neon. Then, the high-purity neon is obtained from the crude neon collected through the pipe 25 through the concentrating means C and the refining means P as in the first embodiment. In addition, high-purity nitrogen gas whose low-boiling components are reduced to a trace amount and whose oxygen concentration is less than 0.3 ppm can be obtained by, for example, hydrogen or the like provided in the upper part of the single-stage rectifier 2 as in the first embodiment of FIG. High-purity liquefied nitrogen is led out from the line 11 below the rectifying unit 4 for concentrating low-boiling components, vaporized through the condensing evaporator 8 and collected from the line 14.

Next, a third embodiment will be described with reference to FIG. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. The major differences between the third embodiment and the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 2 are as follows. In other words, the single rectification column 2 used in each of the first and second embodiments is provided with a liquefied air reservoir 7 for storing liquefied air supplied at reduced pressure from the bottom of the single rectification column 2 at the top. And the condensing evaporator 8 is disposed so as to be immersed in the liquefied air stored in the liquefied air reservoir 7. On the other hand, in the third embodiment, the single rectification is performed. Tower 22
Is not provided with a liquefied air reservoir at the top thereof. Therefore, the condensing evaporator 28 is not immersed in the liquefied air, and is a so-called dry type which is disposed independently of the single-type rectification tower 22 in an adiabatic space. It is called. The refrigeration required to generate the reflux liquid is covered by introducing liquid air from the bottom of the single-column rectification column 22 to the condensation evaporator 28 having an additional flow path through the valve 5 and the pipe 6, As a result, the oxygen-enriched air vaporized is led out from the line 26.

Hereinafter, a third embodiment of FIG. 3 will be described. The raw material air which has been compressed to remove water and carbon dioxide and has been cooled to a temperature close to the boiling point is supplied to the lower part of the single rectification column 22 through the pipe 1, and the low boiling component gas rises in the single rectification column 22. The liquefied gas, which is liquefied upward and descends, comes into contact with the rectifying section 3 of each stage and is rectified and separated by a difference in boiling point. The rectifying section located above has more nitrogen components having a lower boiling point. The lower the rectification portion, the more oxygen components having a higher boiling point.

On the other hand, liquefied air having a higher oxygen content than the raw material air is stored at the bottom of the single-column rectification column 22, and the liquefied air is supplied to a valve 5
Is introduced into a condensing evaporator 28 which is constituted by a plurality of flow paths via a pipe 6 so that each of them can exchange heat. Then, the oxygen-enriched air vaporized using the cold is led out from the pipe 26. The condensing evaporator 28 is connected to a pipe 9 communicating with an upper part of the rectification unit 4 provided for concentrating low boiling components such as hydrogen at the upper part of the single rectification column 22. A gas containing hydrogen and other low-boiling components condensed from the upper part of the pipe 22 is cooled through a pipe 9 through a condensing evaporator 28, liquefied, and returned as a reflux liquid to the upper part of the single-type rectification column 22 through a pipe 10. It is.

In the lower part of one or more stages of rectification sections 4 provided at the upper part of the single-type rectification column 22, low-boiling component gases such as hydrogen rise upward by the rectification section 4. These components are reduced, and high-purity liquefied nitrogen having an oxygen concentration of less than 0.3 ppm is rectified.
It is decompressed and expanded by the valve 12 and introduced into the condensing evaporator 28 through the pipe 13. The condensing evaporator 28 uses the cold for liquefaction of the reflux gas and vaporizes it. Pipe line 14 as extremely pure nitrogen gas reduced to an extremely small amount
Derived and collected.

However, the gas containing hydrogen and other low-boiling components concentrated from the upper part of the single-type rectification column 22 via the pipe 9 is concentrated in the evaporative condenser 28 from the bottom of the single-type rectification column 22. The liquefied air introduced through the line 6 and the lower part of the rectification unit 4 for concentrating low-boiling points such as hydrogen of the single-type rectification column 22 to the condensing evaporator 28 through the line 11, the valve 12 and the line 13 to the condensing evaporator 28. Most of the nitrogen having a high boiling point (boiling point: about −196 ° C. at 1 atm) is liquefied by being cooled in the cold with the introduced high-purity liquefied nitrogen. However, hydrogen with a lower boiling point (boiling point:
Helium (boiling point: 1 atm)
At about -269 ° C), neon (boiling point: about -24 at 1 atm)
6 ° C) and other gases are not liquefied and are in a gaseous state.
75 ppm, hydrogen about 95 ppm, neon about 1710 pp
The nitrogen gas containing the component concentrated to m is led out of the condensing evaporator 28 to the recirculating liquid line 10,
It is collected as crude neon as a neon raw material through a more branched pipe 15.

The thus-collected crude neon gas containing a large amount of neon components is sent from the pipe line 15 to the enrichment means C using a decomposer for decomposing, for example, due to a difference in boiling point.
It is concentrated to a nitrogen gas containing about 14% of helium, about 3% of hydrogen and about 49% of neon, and this is further reduced to 99% using a conventionally known purification means P such as adsorption separation and rectification.
The first and second things that can be collected as high purity neon as described above
This is the same as the respective embodiments.

As described above, also in the third embodiment, as described above, a rectifying section 4 comprising at least one stage or more for concentrating low boiling components such as hydrogen on the upper part of the single rectifying column 22.
Is provided, and high-purity liquefied nitrogen is led out from below the rectifying section 4, and is vaporized using cold in a condensing evaporator 28, and is collected as a trace amount of high-purity nitrogen gas having a low boiling point component. In addition, the gas used for the reflux liquid is derived from above the rectifying section 4 for concentrating low boiling components such as hydrogen having one or more stages provided at the upper part of the single type rectifying column 22,
At the time of liquefaction in order to obtain a reflux liquid which is cooled by the condensing evaporator 28 and returned to the upper portion of the single-column rectification column 22, the low-boiling-point component gas in a non-liquefied gaseous state is concentrated to separate the contained gas. Therefore, the low-boiling components including neon are effectively concentrated, and can be efficiently collected as crude neon as a neon raw material. In addition, it is possible to maintain the normal operation of the conventional single-column rectification type nitrogen production apparatus, and to co-produce these without changing or impairing the power consumption unit.

In the method of the third embodiment, the single rectification column 22 has a simple structure because no liquefied air reservoir is provided at the top, and the condensing evaporator 28 is disposed outside the single rectification column. This is very advantageous in that maintenance and management such as repair and security are easy. Further, in this embodiment, the condensing evaporator 28 for liquefying the gas to be the reflux liquid is not disposed at the top of the single-column rectification column, and the single-column rectification column 22 is not used.
Since it is more independent, there is no need for a head pressure for sending liquefied air from the bottom of the single-column rectification column 22 to cool it to the top as in the first and second embodiments, Therefore, it is not necessary to establish a head pressure. As a result, it is more advantageous than the first embodiment in that the effect of increasing the heat transfer effect and thereby reducing the power consumption can be obtained. In this embodiment, the condensing evaporator 2
As 8, it is preferable to use a plate-fin type heat exchanger capable of exchanging heat with multiple fluids and having high heat exchange efficiency.

FIG. 4 is a system diagram of a single-column rectification column for explaining a fourth embodiment of the present invention. The same components as those in the first to third embodiments shown in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. The feature of the fourth embodiment is that the single rectification column used is a single rectification column in which a liquefied air reservoir is not continuously provided at the top of the rectification column as in the third embodiment shown in FIG. The tower 22 is used. The condensing evaporator 28 is independently disposed outside the rectification column, and liquefied air is supplied from the bottom of the single-column rectification column 22 and the refrigeration is used to liquefy the gas for the reflux liquid. Is a so-called dry type. The mode of operation is the same as that of the third embodiment.

However, the pipeline to be collected as crude neon is:
In the third embodiment, the low-boiling components are concentrated from above a rectifying section 4 having one or more stages provided for concentrating low-boiling components such as hydrogen provided above the single-type rectifying column 22. The separated gas is led out through a line 9, cooled by a condensing evaporator 28, condensed and liquefied, and branched off from a line 10 returned to the upper part of the single rectification column 22 as a reflux liquid. While the low-boiling components including the condensed neon and the like are concentrated and the contained gas is collected as crude neon, in the fourth embodiment, the condensed gas is drawn out from the upper part of the single rectification column 22 through the pipe 9 and condensed. Before introducing a gas containing low-boiling components such as hydrogen and neon, which is circulated through the evaporator 28, the pipe 25 is branched from the pipe 9 before being introduced into the condensing evaporator 28, and is collected as coarse neon from the pipe 25. It was done. That is, coarse neon is sampled from the same position as in the second embodiment.

The crude neon collected in the pipe 25 is supplied to the conventionally known concentrating means C and purifying means P in the same manner as in the above embodiments.
, The neon is purified and collected as high-purity neon of 99% or more. Further, the high-purity nitrogen gas is simultaneously collected from the pipe 14 as in the above embodiments. In the fourth embodiment, as in the third embodiment, the condensing evaporator 28 is of a dry type in which the condensing evaporator 28 is disposed outside the single rectification column 22 and is not immersed in liquefied air. The multi-channels are formed and introduced into a condensing evaporator 28 composed of a plate-fin type heat exchanger each formed to be capable of exchanging heat.

As a result, in the fourth embodiment, the single type rectification column 22 and the condensing evaporator 28 are separated, so that the equipment cost is reduced and the maintenance and management are facilitated.
The same effect as that of the embodiment can be obtained. In the above embodiment, the pipe for collecting crude neon is a pipe branched from the pipe of the reflux liquid after the gas containing the low-boiling component derived from the upper part of the single-column rectification tower is derived via the condensation evaporator. The method of sampling from the pipe and the method of sampling from the pipe branched from the pipe before the introduction of the condensation evaporator have been described separately, but the present invention is not limited to this. Of course, crude neon may be sampled at the same time as adjusting the pressure, and the sampling can be performed without any trouble in operation.

[0031]

The present invention is embodied in the form described above, and has the following effects. In other words, a rectifying section for concentrating low boiling components such as hydrogen is arranged at the upper part of the single rectification column, and it is branched from the gas led out for the reflux liquid from the upper part and collected as crude neon, so that a large amount of neon components is concentrated. Thus, concentration and purification in the subsequent steps can be efficiently operated, and the neon recovery effect can be improved. In addition, by extracting liquefied nitrogen from below the rectification section for concentrating low boiling components such as hydrogen, high purity nitrogen gas in which undesirable low boiling components such as hydrogen are reduced to a trace amount can be simultaneously collected. It is possible to provide a very efficient and high value-added air liquefaction separation method and separation apparatus without waste.

In addition, even during operation, not only can the operation be performed without changing the operation of a conventional high-purity nitrogen production apparatus using a single-column rectification column, but also the power consumption unit for obtaining the product can be extremely reduced. The effect is that the crude neon and the high-purity nitrogen gas having a high recovery effect can be efficiently produced together. In particular, supply of high-purity nitrogen gas in which the content of low-boiling components such as hydrogen is reduced to an extremely small amount is desired, and the utility value in the semiconductor manufacturing industry where neon gas is expected to be used is extremely high.

[Brief description of the drawings]

FIG. 1 is a system diagram of a single rectification column for explaining a first embodiment of an air liquefaction / separation apparatus of the present invention.

FIG. 2 is a system diagram of a single rectification column for explaining a second embodiment of the air liquefaction / separation apparatus of the present invention.

FIG. 3 is a system diagram of a single-column rectification column for explaining a third embodiment of the air liquefaction / separation apparatus of the present invention.

FIG. 4 is a system diagram of a single rectification column for explaining a fourth embodiment of the air liquefaction / separation apparatus of the present invention.

FIG. 5 is a system diagram of a single type rectification column in a conventional air liquefaction / separation apparatus.

FIG. 6 is a system diagram of another single rectification column in a conventional air liquefaction / separation apparatus.

[Explanation of symbols]

1, 6, 9, 10, 11, 13, 14, 15, 16, 2
5, 26 pipeline, 2, 22 single-type rectification column, 3 rectification section, 4 rectification section for concentrating low boiling components such as hydrogen, 5, 12
Valve, 7 liquefied air reservoir, 8, 28 condensation evaporator, C
Concentration means, P purification means

Claims (11)

[Claims] 1. A raw material air is compressed, and after removing water and carbon dioxide gas, it is cooled to almost a boiling point temperature, introduced into a lower part of a single rectification column, and liquefied air is led out from a bottom of the single rectification column. The condensing evaporator is cooled by utilizing this cold, and a gas having a high content of low boiling components such as hydrogen is derived from the upper part of the single type rectifying column and condensed in the condensing evaporator to obtain a reflux liquid. Return to the top of the column, and derive high-purity liquefied nitrogen with a low content of low-boiling components such as hydrogen from at least one theoretical stage below the derivation position of the gas containing a large amount of low-boiling components such as hydrogen,
The condensed evaporator vaporizes and collects as high-purity nitrogen gas, and a part of a gas containing a large amount of low-boiling components such as hydrogen derived from the upper part of the single-column rectification column is branched to obtain a crude neon gas of neon gas. An air liquefaction separation method for producing high-purity nitrogen and crude neon simultaneously, characterized in that it is collected as air. 2. The method according to claim 1, wherein a part of the gas containing a large amount of low-boiling components such as hydrogen derived from the upper part of the single-column rectification column is branched after passing through the condensing evaporator, and uncondensed gas is collected as crude neon. Item 4. An air liquefaction separation method according to Item 1, wherein both high-purity nitrogen and crude neon are produced. 3. The method according to claim 1, wherein a part of the gas containing a large amount of low-boiling components such as hydrogen derived from the upper part of the single-column rectification column is branched and collected as crude neon before being introduced into the condensing evaporator. An air liquefaction separation method for producing both high-purity nitrogen and crude neon according to claim 1. 4. A condensing evaporator cooled by the cooling of the liquefied air is disposed in a liquefied air reservoir partitioned at the top of the single rectification column, and liquefied air from the bottom of the single rectification column is introduced into the liquefied air reservoir. 2. The method of claim 1, wherein the cold is utilized.
An air liquefaction separation method for producing both high purity nitrogen and crude neon according to any one of claims 1 to 3. 5. A condensing evaporator cooled by cooling of liquefied air is disposed independently of a single rectification column, and the liquefied air from the bottom of the single rectification column is conducted to be cooled by utilizing the cold. The air liquefaction separation method for producing high purity nitrogen and crude neon according to any one of claims 1 to 3, characterized in that: 6. A single rectification column for introducing liquefied rectification by introducing raw material air, a condensing evaporator cooled by utilizing refrigeration of liquefied air from the bottom of the single rectification column, A reflux liquid pipeline which derives a gas containing a large amount of low boiling components such as hydrogen from the upper portion of the distillation column and returns the gas to the upper portion of the single-column rectification column via the condensation evaporator, and a gas containing a large amount of low boiling components such as the hydrogen A conduit for extracting liquefied nitrogen having a low content of low boiling components such as hydrogen from at least one theoretical stage below the upper part of the single rectification column to be derived, vaporizing the same through the condensing evaporator, and collecting it as high-purity nitrogen gas An air liquefaction / separation apparatus for producing both high-purity nitrogen and crude neon, which is provided with a crude neon sampling conduit branched from the reflux liquid conduit. 7. A crude neon sampling line branched from a reflux liquid line which returns from the upper part of the single-stage rectification column to the upper part of the single-stage rectification column through the condensing evaporator, is connected to the condensing evaporator of the reflux liquid line. 7. The air liquefaction / separation apparatus according to claim 6, wherein the apparatus is branched by a pipeline. 8. A crude neon sampling line branched from a reflux liquid line which returns from the upper part of the single-stage rectification column to the upper part of the single-stage rectification column via the condensing evaporator, is provided before the introduction of the condensation evaporator into the reflux liquid line. 7. The air liquefaction / separation apparatus according to claim 6, wherein the apparatus is branched by a pipeline. 9. A condensing evaporator cooled by utilizing the refrigeration of liquefied air from the bottom of the single-column rectification column is partitioned at the top of the single-column rectification column, and a liquefied air supply pipe from the bottom of the single-column rectification column is provided. The air liquefaction / separation apparatus according to any one of claims 6 to 8, wherein the apparatus is provided in a liquefied air reservoir and is cooled. 10. A condensing evaporator cooled by utilizing refrigeration of liquefied air from the bottom of a single rectification column, wherein a liquefied air supply pipe from the bottom of the single rectification column is connected to the condensing evaporator. The liquefied air supplied through the pipe is circulated and cooled, and the liquefied air separation apparatus for producing high purity nitrogen and crude neon according to any one of claims 6 to 8 characterized by the above-mentioned. . 11. The single-column rectification column has at least one theoretical point between a position at which a gas containing a large amount of low boiling components such as hydrogen is derived and a position at which liquefied nitrogen having a low content of low boiling components such as hydrogen is derived. The air liquefaction / separation apparatus according to any one of claims 6 to 10, further comprising a rectifying section comprising a stage.