TW201808423A - Gas recovery and purification method achieving the purpose of gas recovery and purification by producing purified gases from a mixed gas - Google Patents

Abstract

A gas recovery and purification method, which comprises: (a) preparing a purification tank which is a double-jacketed purification tank and provided with a sandwich space; (b) preparing a refrigerant storage tank, a mixed gas storage tank and a first gas storage tank; (c) filling the refrigerant into the sandwich space of the purification tank to maintain the temperature in the purification tank within a predetermined temperature range; (d) filling the mixed gas into the purification tank for freezing and solidification to produce residual solid substances composed of non-gaseous substances and a first purified gas composed of gaseous substances; accumulating the residual solid substance in the purification tank; discharging the first purified gas to the first gas storage tank; thereby achieving the purpose of gas recovery and purification.

Description

Gas recovery purification method

The invention relates to a gas recovery and purification method; in particular, it relates to a method that utilizes the basic characteristics of solids without vapor pressure to freeze part of the gas in the mixed gas into a solid, so that only one rare gas in the gas phase is purified. A method for recovering and purifying a rare gas and obtaining a high-purity rare gas.

In the process of the semiconductor industry, a large amount of high-purity rare gases are used, and a large amount of rare gas exhaust gas is also generated. These rare gas exhaust gases are a mixture of two or more rare gases and must be separated and purified before being reused, such as neon, The mixed gas of argon and krypton must be purified and separated before being reused.

Patent Document 1: US5294422A. Patent Document 1 is a rare gas purification technology disclosed in the United States in 1944. It uses a gas trap made of an alloy of two metals, zirconium and vanadium, to remove impurities in the rare gas and obtain a rare gas with high purity.

Patent Document 2: EP0422559A1. Patent Document 2 is a rare gas purification technology disclosed in Europe in 1991. It uses metals and ceramics to produce porous hydrogen storage materials to remove impurities in the rare gases and obtain rare gases with high purity.

Patent Document 3: US6843973 (B2). Patent Document 3 is a rare gas purification technology disclosed in the United States in 2002. Krypton and xenon are recovered from oxygen.

The aforementioned gas traps or hydrogen storage materials are used to remove impurities in rare gases by adsorption or chemical reaction methods to obtain purified rare gases. As for the distillation method, liquid evaporation is used for gaseous separation. Pressure, so a rectification column is required to separate them, and it is difficult to achieve high purity gases.

In view of this, the inventors have been thinking hard, actively researching, and having years of experience in researching related products, and after continuous research and improvement, finally developed the present invention.

An object of the present invention is to provide a gas recovery and purification method capable of recovering and purifying a gas.

The steps of the present invention to achieve the above objective include: a) preparing a purification tank, which is a double-layered purification tank with a sandwich space; b) preparing a refrigerant storage tank, a mixed gas storage tank, and a first gas Storage tank; c) filling refrigerant into the interlayer space of the purification tank, so as to maintain the temperature in the purification tank within a predetermined temperature range; d) pouring mixed gas into the purification tank for freeze solidification, resulting in non-gaseous substances The remaining solid material and the first purified gas composed of gaseous materials; the remaining solid material is accumulated in the purification tank; the first purified gas is discharged to the first gas storage tank; Purpose of gas recovery and purification.

Preferably, step b) comprises: step b1) before purging the refrigerant into the interlayer space of the purification tank, first performing purification tank drainage means to exhaust the gas in the purification tank; the purification tank drainage means includes: Use the vacuum method and / or fill the purification tank with the same gas as the first purification gas; by this method, the degree of gas purification can be improved.

Preferably, the predetermined temperature range of step c) is higher than the boiling point of "the first lowest freezing point in the mixed gas" and lower than the freezing point of "the second lowest freezing point in the mixed gas"; Obtain a high-purity gas.

Preferably, after step d), the following steps are further included: e) increasing the temperature in the purification tank so that the temperature in the purification tank is higher than the boiling point of "the lowest boiling point of the remaining solid matter" for vaporization to produce gaseous substances The second type of purified gas and the remaining solid matter composed of other substances; in the process of vaporizing "the lowest boiling point among the remaining solid substances", while waiting for the "lowest boiling point among the remaining solid substances" to vaporize, The vaporized gas is discharged to a second gas storage tank, which can achieve the purpose of recovering and purifying the gas.

Preferably, the step d) comprises: step d1) before increasing the temperature in the purification tank, first performing a purification tank drainage means to exhaust the gas in the purification tank; the purification tank drainage means includes: using a vacuum method And / or filling the purification tank with the gaseous "lowest boiling point of the remaining solid matter"; by this method, a high-purity gas can be obtained.

Preferably, after step e), the following steps are further included: f) Step e) is repeatedly performed at least once to achieve the purpose of recovering and purifying the gas.

Another object of the present invention is to provide a gas recovery and purification method capable of recovering and purifying neon gas, argon gas and krypton gas.

The steps of the present invention to achieve the above objective include: a) preparing a purification tank, which is a double-layered purification tank with a sandwich space; b) preparing a refrigerant storage tank, a mixed gas storage tank, and a first gas Storage tank; the refrigerant is liquid nitrogen; the mixed gas includes: neon, argon, and krypton; c) the refrigerant is filled into the interlayer space of the purification tank, so that the purification tank The temperature inside is maintained within a predetermined temperature range; the predetermined temperature range is higher than the boiling point of neon and lower than the freezing point of argon; d) the mixed gas is poured into a purification tank for freeze solidification, resulting in solid argon and krypton Residual solid matter, and the first purified gas composed of neon gas; the residual solid matter is accumulated in the purification tank; the first purified gas is discharged to the first gas storage tank; by this method, it can be achieved The purpose of recovery and purification of neon gas.

Preferably, step b) comprises: step b1) before purging the refrigerant into the interlayer space of the purification tank, first performing purification tank drainage means to exhaust the gas in the purification tank; the purification tank drainage means includes: The vacuum method is used and / or the purification tank is filled with neon gas; by this method, high purity neon gas can be obtained.

Preferably, after step d), the following steps are further included: e) increasing the temperature in the purification tank so that the temperature in the purification tank is higher than the boiling point of argon and lower than the freezing point of tritium for argon vaporization to produce argon. The second purified gas composed of gas and the remaining solid matter composed of solid krypton; in the process of argon vaporization, while waiting for the argon to vaporize, the vaporized argon gas is discharged to a second gas storage tank ; With this method, the purpose of recovering and purifying argon can be achieved.

Preferably, the step d) comprises: step d1) before increasing the temperature in the purification tank, first performing a purification tank drainage means to exhaust the gas in the purification tank; the purification tank drainage means includes: using a vacuum method And / or filling the purification tank with argon; by this method, high-purity argon can be obtained.

Preferably, after step e), the following steps are further included: f) Increasing the temperature in the purification tank so that the temperature in the purification tank is higher than the boiling point of thorium to perform thorium vaporization and generate a third kind of thorium Purified gas; in the process of vaporizing radon, while waiting for radon to vaporize, the vaporized radon The gas is discharged to a third gas storage tank; by this method, the purpose of recovering and purifying radon gas can be achieved.

Preferably, step e) includes: step e1) before increasing the temperature in the purification tank, first performing a purification tank drainage means to exhaust the gas in the purification tank; the purification tank drainage means includes: using a vacuum method And / or purge radon gas into the purification tank; by this method, high purity radon gas can be obtained.

In order to achieve the above and other objectives, the present invention adopts the technical means, components, and effects thereof. A preferred embodiment is illustrated below with reference to the drawings.

a, b‧‧‧ preparation steps

b1‧‧‧Draining steps

c‧‧‧Temperature control step

d‧‧‧Feeding steps

d1‧‧‧Draining steps

e‧‧‧Temperature control step

e1‧‧‧Draining steps

f‧‧‧Temperature control step

FIG. 1 is a flowchart of a first embodiment of the present invention.

FIG. 2 is a flowchart of a second embodiment of the present invention.

FIG. 3 is a flowchart of a third embodiment of the present invention.

FIG. 4 is a flowchart of a fourth embodiment of the present invention.

As shown in FIG. 1, the first embodiment of the present invention, the gas recovery and purification method of the present invention includes the following steps: a) preparing a purification tank, which is a double-layered purification tank with a sandwich space; b) preparing a freezing Agent storage tank, a mixed gas storage tank, and a first gas storage tank; c) the refrigerant is filled into the interlayer space of the purification tank to maintain the temperature in the purification tank within a predetermined temperature range; d) the mixed gas Filled into the purification tank for freeze solidification to produce the remaining solid matter composed of non-gaseous substances and the first purified gas composed of gaseous substances; the remaining solid matter accumulated in the purification tank; the first purified gas It is discharged to the first gas storage tank; by this method, the purpose of recovering and purifying the gas can be achieved. More details below To explain.

Step a) is a preparation step. A purification tank is prepared. The purification tank is a double-layered purification tank with a sandwich space. The interlayer space is used to place a refrigerant to control the temperature in the purification tank, and it is connected to the purification tank, for example, it is arranged around the periphery of the purification tank.

Step b) is a preparation step; preparing a refrigerant storage tank, a mixed gas storage tank, and a first gas storage tank. The refrigerant may be a low-temperature liquid such as liquid nitrogen. The mixed gas may contain various gases, and of course, it may also contain a rare gas, such as a mixed gas containing neon, argon, and krypton.

Step c) is a temperature control step; the refrigerant is poured into the interlayer space of the purification tank, thereby maintaining the temperature in the purification tank within a predetermined temperature range. A structure capable of conducting heat can be provided between the interlayer space and the internal space of the purification tank, so as to control the temperature of the purification tank by using heat conduction. Therefore, when the refrigerant enters the interlayer space, the temperature of the purification tank can be affected, and the temperature in the purification tank can be controlled by controlling the temperature of the refrigerant.

Step d) is a feeding step; the mixed gas is poured into a purification tank for freeze solidification to produce a residual solid substance composed of a non-gaseous substance and a first purified gas composed of a gaseous substance; the residual solid substance accumulates in Inside the purification tank; the first purification gas is discharged to the first gas storage tank. When this step is performed, when the mixed gas is poured into the purification tank, the gas with a freezing point higher than a predetermined temperature will be solidified, so the gas with a low freezing point can be effectively separated from the mixed gas. In addition, when the mixed gas is poured into the purification tank, it can be performed at a predetermined flow rate to ensure that there is a sufficient freezing retention time before the gas is discharged to the first gas storage tank, thereby obtaining a purified gas.

When performing the control of the predetermined temperature range in step c), the predetermined temperature The temperature range must be at least higher than the boiling point of the "lowest freezing point in mixed gas". For example, the temperature range of the set temperature should be higher than the boiling point of the "lowest freezing point in mixed gas" and lower than the "mixed gas The solidification point of the second lowest solidification point in the middle "; in this way, when step d) is performed, only the" lowest solidification point in the mixed gas "in the purification tank can be left in a gaseous state, and a high purity gas. Of course, if the "lowest freezing point in the mixed gas" is known to be a small amount of negligible gas, then such factors can be ignored when controlling the predetermined temperature range; for example, when the mixed gas is mostly composed of neon, argon , Radon and other gases, and it also contains a small amount of negligible helium with a freezing point lower than neon, the predetermined temperature range can be controlled above the boiling point of neon and below the freezing point of argon To obtain purified neon.

In addition, when controlling the predetermined temperature range in step c), the predetermined temperature range should be kept below the freezing point of "the second lowest freezing point in the mixed gas" as far as possible to ensure the "second freezing point in the mixed gas" The "lower" is frozen.

When step d) is performed, the volume of the solidified gas in the mixed gas is greatly reduced, and the uncondensed gas is discharged into the first gas storage tank, so it can operate for a long time.

The aforementioned first purified gas can be compressed by a compressor and sent to a first gas storage tank for storage.

The aforementioned purification tank may have a mixed gas control valve and at least one discharge valve; the mixed gas control valve may control the flow rate of the mixed gas into the purification tank, thereby ensuring that the mixed gas has a sufficient freezing retention time in the purification tank. In addition, the mixed gas control valve and the discharge valve can be spaced a predetermined distance apart, so that the gas having a freezing point higher than a predetermined temperature range It can be solidified when flowing from the mixed gas control valve to the discharge valve.

As mentioned earlier, the interlayer space uses heat conduction to control the temperature in the purification tank. Therefore, after the mixed gas enters the purification tank, most of the gases with a high freezing point will solidify on the inner wall surface of the purification tank. In this case, structures such as a grid plate, a meandering channel, and a blocking net body may be provided inside the purification tank between the mixed gas control valve and the discharge valve, thereby increasing the efficiency of solidification.

As shown in FIG. 2, in the second embodiment of the present invention, step b) may further include: step b1) before the refrigerant is filled into the interlayer space of the purification tank, a purification tank drainage method is first performed to drain the purification tank. The purification means of the purification tank includes: using a vacuum method and / or filling the purification tank with the same gas as the first purification gas.

Before the refrigerant is filled into the interlayer space of the purification tank, the purification tank contains general gas; the composition of the general gas is complex, and there may be gases whose freezing point is lower than the freezing point of the "lowest freezing point in the mixed gas", so Before filling the mixed gas, the gas in the purification tank can be purged to improve the degree of purification. There are many ways to evacuate the gas in the purification tank, such as evacuating the purification tank. In addition, the degree of vacuum in the purification tank depends on the use requirements. After the purification tank is evacuated, the same gas as the first purified gas can be filled in to purify the remaining gas; The gas will be discharged to a first gas reserve storage tank together with the gas released from the mixed gas, and can be used, for example, for preparing secondary products.

As mentioned above, when step d) is carried out, solidified residual solid matter is accumulated in the purification tank. The remaining solid matter may of course also contain substances such as noble gases. Therefore, other steps can be continued after step d). It is explained below.

The third embodiment of the present invention as shown in FIG. 3, after step d), the following steps may be further performed: e) increasing the temperature in the purification tank, so that the temperature in the purification tank is higher than "the lowest boiling point of the remaining solid matter" ”Boiling point for vaporization, generating a second purified gas composed of gaseous substances, and residual solid substances composed of other substances; in the process of vaporizing“ the lowest boiling point among the remaining solid substances ”, while waiting for the“ remaining "The lowest boiling point of solid matter" is vaporized, and the vaporized gas is discharged to a second gas storage tank; by this method, the rare gas in the remaining solid matter can be further recovered and purified.

Of course, the same as step b), step d) may further include: step d1) before increasing the temperature in the purification tank, performing purification tank exhaustion means to exhaust the gas in the purification tank; the purification tank exhausting means Including: using the vacuum method and / or filling the purification tank with gaseous "the lowest boiling point of the remaining solid matter".

Regarding the method for increasing the temperature of the purification tank, as mentioned above, the cryogen may be a low-temperature liquid such as liquid nitrogen; therefore, a pressure regulating valve may be provided in the interlayer space to increase the temperature of the refrigerant, thereby increasing the temperature in the purification tank.

After completing step e), if there are remaining solids in the purification tank, the following steps can be further performed: e1) Repeat step d1) at least once; f) Repeat step e) at least once to obtain more types of purification The gas is stored in different storage tanks.

The operation of purifying the gas in the purification tank performed in steps b1), d1), and e1) depends on demand. For example, not purifying the gas in the purification tank will reduce the purity of the gas obtained, but if it is within an acceptable range, it may not be purging the gas in the purification tank.

The fourth embodiment of the present invention shown in FIG. 4 is applicable to recovering and purifying various mixed gases. In this embodiment, liquid nitrogen is specifically used as a refrigerant, and a mixture of neon, argon, and nitrogen is used. The resulting mixed gas can achieve the purpose of recovering and purifying rare gases such as neon, argon and krypton; it is described below.

In this embodiment, the gas recovery and purification method includes the following steps: a) preparing a purification tank, which is a double-layered purification tank with an interlayer space; b) preparing a refrigerant storage tank and a mixed gas storage tank And a first gas storage tank; the refrigerant is liquid nitrogen; the mixed gas includes: neon, argon, and krypton; c) the refrigerant is filled into the interlayer space of the purification tank to maintain the temperature in the purification tank Within a predetermined temperature range; the predetermined temperature range is higher than the boiling point of neon and lower than the freezing point of argon; d) the mixed gas is poured into a purification tank for freeze solidification to produce a residual solid substance composed of solid argon and nitrogen And the first purification gas composed of neon gas; the remaining solid matter is accumulated in the purification tank; the first purification gas is discharged to the first gas storage tank; e) the temperature in the purification tank is increased so that The temperature in the purification tank is higher than the boiling point of argon and lower than the freezing point of tritium for argon vaporization to produce a second purified gas composed of argon and the remaining solid matter composed of solid tritium; in In the process of vaporizing argon, while waiting for the argon to vaporize, exhaust the vaporized argon to a second gas storage tank; f) increase the temperature in the purification tank so that the temperature in the purification tank is higher than the boiling point of tritium, and The radon vaporization is performed to generate a third purified gas composed of nitrogen; in the process of radon vaporization, while waiting for radon vaporization, the vaporized radon gas is discharged to a third gas storage tank; by this method, To achieve the purpose of recovering and purifying gas, especially recovering and purifying neon, argon and krypton.

The refrigerant stored in the refrigerant storage tank prepared in step b) is liquid nitrogen, which can reach a low temperature of -196 ° C, and the temperature can be increased by means such as pressure adjustment. In addition, the mixed gas stored in the mixed gas storage tank includes neon gas, argon gas, and radon gas. In addition, step b) includes: step b1) before purging the refrigerant into the mezzanine space of the purification tank, first purifying the tank to purify the gas in the purification tank; the purification tank purging means includes: using a vacuum Way and / or inject neon gas into the purification tank.

During step c), the temperature in the purification tank can be controlled at -196 ° C.

After step d), argon having a freezing point of -189 ° C and radon having a freezing point of -157 ° C can be freeze-solidified into solids, and the remaining component is neon gas having a freezing point of -248 ° C as a gas. In addition, step d) includes: step d1) before increasing the temperature in the purification tank, first performing a purification tank drainage means to exhaust the gas in the purification tank; the purification tank drainage means includes: using a vacuum method and / or The purification tank was purged with argon.

When performing step e), the temperature of the liquid nitrogen can be increased by means of, for example, pressure adjustment, thereby increasing the temperature in the purification tank, so that the temperature in the purification tank is between -163 ° C and -180 ° C, and then the solid state Argon vaporizes into a gas because argon has a boiling point of -185.8 ° C; and because rhenium has a boiling point of -157 ° C, rhenium is still a solid. In addition, step e) includes: step e1) before increasing the temperature in the purification tank, first performing a purification tank drainage means to exhaust the gas in the purification tank; the purification tank drainage means includes: using a vacuum method and / or The purification tank was purged with argon.

When performing step f), the temperature of the liquid nitrogen can be increased by means of pressure adjustment, for example, and the temperature in the purification tank can be increased, so that the temperature in the purification tank is higher than the boiling point of tritium, that is, higher than -152.9 ° C.

In each of the foregoing steps of controlling the predetermined temperature range, the predetermined temperature range can be as close as possible to the condensation point of the gaseous substance in the purification tank. For example, when performing step f), the predetermined temperature range should be as close as possible to -152.9 ° C (for example, -150 ° C), so as to maintain the generated radon gas at a temperature close to the freezing point, thereby facilitating the compressed radon gas to be stored in the Three rare gas storage tanks.

The above-mentioned embodiments in this case are provided for convenience of explanation only. When the meaning of this case cannot be limited in this way, that is, all kinds of transformation designs based on the scope of patent applications listed should be included in the scope of patents in this case.

a, b‧‧‧ preparation steps

c‧‧‧Temperature control step

d‧‧‧Feeding steps

Claims (12)

A gas recovery and purification method includes the following steps: a) preparing a purification tank, which is a double-layered purification tank with a sandwich space; b) preparing a refrigerant storage tank, a mixed gas storage tank, and a first A gas storage tank; c) the refrigerant is filled into the interlayer space of the purification tank, so that the temperature in the purification tank is maintained within a predetermined temperature range; d) the mixed gas is filled into the purification tank for freeze solidification, resulting in a non-gaseous state The remaining solid substance composed of the substance and the first purified gas composed of the gaseous substance; the remaining solid substance accumulated in the purification tank; the first purified gas was discharged to the first gas storage tank. The gas recovery and purification method according to claim 1, wherein step b) includes: step b1) before purging the refrigerant into the interlayer space of the purification tank, first purifying the tank to purify the gas in the purification tank ; The purification tank drainage means include: using a vacuum method and / or filling the purification tank with the same gas as the first purification gas. The gas recovery and purification method according to claim 1, wherein the predetermined temperature range of step c) is higher than the boiling point of "the first lowest freezing point in the mixed gas" and lower than the "the second lowest freezing point in the mixed gas" ”Freezing point. The gas recovery and purification method according to claim 1, wherein after step d), the following steps are further included: e) increasing the temperature in the purification tank so that the temperature in the purification tank is higher than "the lowest boiling point of the remaining solid substances" Boiling point and below the freezing point of other substances in the remaining solid matter for vaporization to produce a second purified gas composed of a gaseous substance, and Residual solid matter composed of other substances; in the process of vaporizing the "lowest boiling point in the remaining solid matter", while waiting for the "lowest boiling point in the remaining solid matter" to vaporize, exhaust the vaporized gas to a second gas storage groove. The gas recovery and purification method according to claim 4, wherein the step d) comprises: step d1) before increasing the temperature in the purification tank, performing a purification tank drainage means to purify the gas in the purification tank; the purification tank The means of purging include: using a vacuum method and / or filling the purification tank with the same gas as the second purification gas to be subsequently vaporized. The gas recovery and purification method according to claim 5, wherein the step e) further includes the following steps: f) The step e) is repeatedly performed at least once. A gas recovery and purification method includes the following steps: a) preparing a purification tank, which is a double-layered purification tank with a sandwich space; b) preparing a refrigerant storage tank, a mixed gas storage tank, and a first A gas storage tank; the refrigerant is liquid nitrogen; the mixed gas includes: neon, argon, and krypton; c) the refrigerant is filled into the interlayer space of the purification tank, thereby maintaining the temperature in the purification tank at a predetermined level Within the temperature range; the predetermined temperature range is higher than the boiling point of neon and lower than the freezing point of argon; d) the mixed gas is poured into a purification tank for freeze solidification to produce a residual solid substance composed of solid argon and krypton, and The first purified gas composed of neon gas; the remaining solid matter is accumulated in the purification tank; the first purified gas is discharged to the first gas storage tank. The gas recovery and purification method according to claim 7, wherein step b) includes: step b1) before purging the refrigerant into the interlayer space of the purification tank, first purifying the tank to purify the gas in the purification tank ; The purification tank drainage means include: using a vacuum method and / or filling the purification tank with neon gas. The gas recovery and purification method according to claim 7, wherein step d) further includes the following steps: e) increasing the temperature in the purification tank so that the temperature in the purification tank is higher than the boiling point of argon and lower than the freezing point of tritium To carry out argon vaporization, to produce a second purified gas composed of argon, and the remaining solid material composed of solid krypton; in the process of argon vaporization, while waiting for argon to vaporize, the vaporized argon The gas is discharged to a second gas storage tank. The gas recovery and purification method according to claim 9, wherein the step d) comprises: step d1) before increasing the temperature in the purification tank, performing a purification tank drainage means to purify the gas in the purification tank; the purification tank Means of purging include: using a vacuum method and / or pouring argon into the purification tank. The gas recovery and purification method according to claim 9, wherein after step e), the following steps are further included: f) increasing the temperature in the purification tank so that the temperature in the purification tank is higher than the boiling point of thorium for thorium vaporization to produce A third type of purified gas composed of radon; in the process of radon vaporization, while waiting for radon vaporization, the vaporized radon gas is discharged to a third gas storage tank. The gas recovery and purification method according to claim 11, wherein the step e) comprises: step e1) before increasing the temperature in the purification tank, performing a purification tank exhausting method to purify the gas in the purification tank; the purification tank Means of drainage include: using a vacuum method and / or pouring radon into the purification tank.