TWI618568B - Gas recovery and purification process - Google Patents

Abstract

A process for recovering and purifying a gas, comprising: a) preparing a refrigerant, a mixed gas, a refrigerating liquefaction tank, and a freezing and solidifying tank; b) maintaining the refrigerating liquefaction tank in a predetermined temperature range by using a refrigerant, so that the mixing After the gas passes through the refrigerating liquefaction tank, at least one substance is liquefied; and the temperature in the freezing and solidifying tank is maintained within a predetermined temperature range by using a refrigerant, so that when the mixed gas passes through the freezing and solidifying tank, most of the The substance will be solidified, leaving only one substance in a gaseous state; c) the mixed gas is sequentially passed through the refrigerating liquefaction tank, the freezing and solidifying tank for refrigerating and solidifying; and the gaseous substance discharged from the freezing and solidifying tank is The purified substance; the liquid substance discharged from the refrigerating liquefaction tank is the purified substance; thereby the purpose of recovering and purifying the gas can be achieved by the process.

Description

Gas recovery and purification process

The invention relates to a process for recovering and purifying a gas, in particular to a method for controlling the temperature of a plurality of purification tanks by using, for example, liquid nitrogen as a refrigerant, and separately purifying the substances in the mixed gas, and conveniently recovering the substances. In addition, by discharging the liquid substance in the liquefaction tank, the load of the purification tank can be reduced, thereby further improving the overall processing amount of the gas recovery and purification process.

In the manufacturing process of the semiconductor industry, a large amount of high-purity rare gas is used, and a large amount of rare gas exhaust gas is also generated. These rare gas exhaust gas are a mixed gas of two or more kinds of rare gases, and must be separated and purified before being reused, for example, The mixed gas of argon and helium must be purified by separating helium, argon and helium.

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

Patent Document 2: EP0422559A1. Patent Document 2 is a rare gas purification technique disclosed in Europe in 1991, which uses a metal and ceramic to produce a porous hydrogen storage material to remove impurities in a rare gas to obtain a high-purity rare gas.

Patent Document 3: US6843973 (B2). Patent Document 3 is 2002 A rare gas purification technique disclosed in the United States in the United States, which uses distillation to recover lanthanum and cerium from oxygen.

The gas trap or the hydrogen storage material mentioned above removes impurities in the rare gas by adsorption or chemical reaction to obtain a purified rare gas, and the distillation method is used for liquid evaporation to a gaseous state, and the liquid also has steam. Pressure, so a rectification column is required to separate them, and it is difficult to achieve high purity gas.

In addition, in addition to the problem of wasted waste by arbitrarily discharging rare gases, the random discharge of harmful gases may cause environmental pollution. In addition, when a harmful gas leak or an emergency discharge of a harmful gas occurs, it may cause environmental pollution; therefore, emergency treatment of harmful gas is also an urgent problem to be solved.

In view of this, the inventors have developed the present invention through careful research, active research, and years of experience in related product research, and continuous research and improvement.

The object of the present invention is to provide a process for recovering and purifying a gas which can be purified, reused, and reused, can be used to treat the leakage of harmful gases, and can also treat the emergency discharge of harmful gases.

The steps of the present invention for achieving the above object include: a) preparing a refrigerant, a mixed gas, a refrigerating liquefaction tank and a freezing and solidifying tank; b) using a refrigerant to maintain the refrigerating liquefaction tank within a predetermined temperature range, so that when the mixed gas passes through the freezing After the liquefaction tank, at least one substance is liquefied; and the temperature in the freeze-solidification tank is maintained within a predetermined temperature range by using a refrigerant, so that most of the substances are solidified when the mixed gas passes through the freeze-solidification tank, and only The remaining material is in a gaseous state; c) the mixed gas is sequentially passed through the cold The liquefaction tank and the freeze-cure tank are used for refrigerating and solidifying; the gaseous substance discharged from the freeze-cure tank is the purified substance; and the liquid substance in the refrigerating liquefaction tank is discharged, that is, the purified substance.

Preferably, after step a), the method further comprises the steps of: a1) discharging the refrigerating liquefaction tank and the freezing and solidifying tank, thereby draining the gas therein; and the means for discharging comprises: using a vacuuming method and/or sending The gas is the same as the gas having the lowest freezing point in the mixed gas; this step can increase the degree of purification of the substance.

Preferably, after step c), the method further comprises the steps of: d) stopping the feeding of the mixed gas, and then melting or vaporizing the solid matter in the freezing and solidifying tank to be discharged, which is the purified substance; After the substance.

Preferably, after step d), the method further comprises the steps of: d1) performing a draining means on the freezing and solidifying tank to drain the gas therein; and the means for removing the vacuum comprises: using a vacuuming method and/or feeding into the same The same gas as the solid material; this step increases the degree of material purification.

Preferably, the refrigerant is liquid nitrogen; the solidification point of all the substances in the mixed gas is above -196 ° C, or only one substance has a freezing point below -196 ° C; this step can be utilized easily and at low cost. Liquid nitrogen is a refrigerant to reduce costs.

Preferably, step a) is provided with one or more auxiliary purification tanks between the freezing liquefaction tank and the freezing solidification tank; the auxiliary purification tank is connected in series between the freezing liquefaction tank and the freezing solidification tank; step b) Maintaining the temperature of the auxiliary purification tank within a predetermined temperature range by using a refrigerant, so that the substance liquefied in the previous purification tank is solidified in the auxiliary purification tank, and one of the remaining gases is liquefied; Step, can be purified and returned Receive more types of substances.

Preferably, the refrigerating liquefaction tank, the freezing and solidifying tank and the auxiliary purification tank respectively have a sandwich space; the refrigerant is sent into the interlayer space of the purification tank; the inner wall of the purification tank is welded with a freezing piece to increase the freezing area. With this structure, the freezing efficiency can be improved, and the gas can be easily liquefied and/or solidified in each purification tank.

Preferably, in step c), the mixed gas is sent to the refrigerating liquefaction tank and the freezing and solidifying tank at a predetermined flow rate, so that the mixed gas has sufficient freezing residence time in the purification tanks.

The present invention has been made in view of the above-described and other objects, the technical means, the components and the effects thereof.

a‧‧‧Preparation steps

A1‧‧‧cleaning steps

B‧‧‧temperature control steps

C‧‧‧feeding, purification and recovery steps

d‧‧‧Stopping steps

D1‧‧‧Draining steps

e‧‧‧Solid recovery steps

Figure 1 is a flow chart of a first embodiment of the present invention.

Figure 2 is a schematic illustration of step c) of the first embodiment of the present invention.

Figure 3 is a schematic illustration of step e) of the first embodiment of the present invention.

Figure 4 is a flow chart of a second embodiment of the present invention.

Figure 5 is a schematic illustration of step c) of a second embodiment of the present invention.

Figure 6 is a schematic illustration of step e) of a second embodiment of the invention.

As shown in the first embodiment of FIG. 1, the gas recovery and purification process of the present invention comprises the steps of: a) preparing a refrigerant, a mixed gas, a refrigerating liquefaction tank and a freezing and solidifying tank; b) using a refrigerant to make the refrigerating tank Maintained within a predetermined temperature range such that at least one substance is liquefied when the mixed gas passes through the refrigerating liquefaction tank; and the refrigerant is solidified by the refrigerant The temperature in the tank is maintained within a predetermined temperature range, so that when the mixed gas passes through the freeze-solidification tank, most of the substance is solidified, and only one substance remains in a gaseous state; c) the mixed gas is sequentially passed through the freezing liquefaction tank, The freeze-solidification tank is used for freezing liquefaction and solidification; the gaseous substance discharged from the freeze-solidification tank is the purified substance; the liquid substance in the refrigeration liquefaction tank is discharged, which is the purified substance; thereby the recovery and purification can be achieved by the process The purpose of the substance. The details will be explained below.

Step a) is a preparation step; preparing a refrigerant, a mixed gas, a refrigerating liquefaction tank, and a freezing and solidifying tank.

The cryogen may be a cryogenic liquid which is used to cure all of the substances in the mixed gas, or to cure most of the substances in the mixed gas, leaving only one substance not cured. For example, if liquid nitrogen is used as the refrigerant, the freezing point of all the substances in the mixed gas is above -196 ° C, or only one substance has a freezing point below -196 ° C.

The mixed gas may contain various gases, and may of course contain a rare gas such as a mixed gas containing helium, argon or helium.

The refrigerating liquefaction tank is connected in series with the freezing and solidifying tank.

Step b) is a temperature control step; the freezing liquefaction tank is maintained in a predetermined temperature range by using a refrigerant, so that at least one substance is liquefied after the mixed gas passes through the refrigerating liquefaction tank; and the freezing agent is used to make the freezing solidification tank The temperature is maintained within a predetermined temperature range such that as the mixed gas passes through the freeze-solidification tank, most of the material is solidified, leaving only one material in a gaseous state.

As shown in FIG. 2, step c) is a feeding, purifying and recovering step; the mixed gas is sequentially passed through a refrigerating liquefaction tank and a freezing solidification tank for refrigerating and solidifying; and the gaseous substance discharged from the freezing and solidifying tank is purified. Substance; the liquid substance discharged from the refrigerating liquefaction tank is the purified substance.

After the mixed gas is sent to the refrigerating liquefaction tank, the substance whose condensation point is higher than the freezing point lower than the temperature in the refrigerating liquefaction tank will be liquefied; then the remaining gas will enter the freezing solidification tank, and most of the substances will solidify. Only one substance remains in a gaseous state, that is, only the substance having a freezing point lower than the temperature in the freezing and solidifying tank is in a gaseous state.

By the above steps a) to c), the present invention can effectively purify the substance, and can conveniently recover the substances, for example, by being stored in a storage tank; and further, by purging the liquid substance in the refrigerating liquefaction tank, the purification can be reduced. The load of the tank can effectively increase the overall total processing capacity and achieve the effect of long-term continuous operation. Further, when the mixed gas is, for example, a mixed gas discharged from the industry, the recyclable gas can be recovered and reused in the present invention, which not only reduces waste but also protects the environment. Further, of course, the mixed gas may contain a harmful gas such as chlorine gas; in this case, in addition to recovering and purifying the chlorine gas, the harmful gas may be first solidified to discharge other gases into the atmosphere, thereby leaking as a harmful gas. Emergency treatment to meet environmental protection needs.

The step a) may further include the step a1); the step a1) is a draining step; the freezing liquefaction tank and the freezing and solidifying tank are drained to remove the gas therein; and the discharging means includes: using vacuuming The method and/or feeding the same gas as the gas having the lowest freezing point in the mixed gas.

When the foregoing step c) is performed, the solid content is gradually accumulated in the freeze-solidification tank as time passes; when the solid matter in the freeze-solidification tank is accumulated to a predetermined amount or full load, the following steps may be followed: d) stop The mixed gas is fed; e) the solid matter in the freeze-solidification tank is melted or vaporized and discharged, that is, the purified substance.

Step d) is the stopping step; the feeding of the mixed gas is stopped to proceed to the next step.

As shown in FIG. 3, the step e) is a solid recovery step, and the solid matter in the freeze-solidification tank is melted or vaporized and discharged, that is, the purified substance.

After the foregoing step d), the step d1) may further be included; the step d1) is a draining step; the freezing and solidifying tank is subjected to a draining means for draining the gas therein; and the discharging means comprises: using a vacuuming method and/or Or feed the same gas as the solid matter in it.

As shown in the second embodiment shown in FIG. 4, the present invention is applicable to the recovery and purification of various mixed gases. Further, a plurality of substances may be present in the mixed gas. In this case, the aforementioned step a) may be performed in the freezing liquefaction tank. One or more auxiliary purification tanks are provided between the freezing and solidifying tanks; the auxiliary purification tank is connected in series between the freezing liquefaction tank and the freezing and solidifying tank; the above step b) is to use the refrigerant to make the temperature of the auxiliary purification tanks Maintained within a predetermined temperature range such that the substance liquefied in the previous purification tank is solidified in the auxiliary purification tank, and one of the remaining gases (argon) is liquefied; thus, when in the mixed gas When a plurality of substances are contained, a purified substance can be obtained by adding an auxiliary purification tank between the freezing liquefaction tank and the freezing and solidifying tank. For convenience of explanation, the liquid nitrogen is used as a refrigerant, and a mixed gas composed of helium, argon, and helium is used as an example.

Step a) preparing liquid nitrogen; a mixed gas composed of helium, argon and helium; a refrigerating liquefaction tank; an auxiliary purification tank; and a freezing and solidifying tank. The freezing liquefaction tank, the freezing and solidifying tank and the auxiliary purification tank may respectively have a sandwich space; the refrigerant is sent into the interlayer space of the purification tanks; The inner wall of the purification tank is welded with a freezing piece to increase the freezing area; thereby, the structure can improve the freezing efficiency and facilitate the liquefaction and/or solidification of the gas in each purification tank.

Step a1) uses a vacuuming method and/or feeding helium.

Step b) using the refrigerant to maintain the refrigerating liquefaction tank, the auxiliary purification tank, and the freeze-solidification tank within a predetermined range.

The refrigerating liquefaction tank is maintained at a temperature below the condensation point of -152.9 ° C and above a predetermined temperature range of -157.3 ° C, such as -155 ° C.

The auxiliary purification tank is maintained at a freezing point below the freezing point of -157.3 ° C, below the argon condensation point -185 ° C and above the freezing point of argon -189.35 ° C, such as -186 ° C.

The freeze-cure tank is maintained at a temperature below the freezing point of argon of -189.35 ° C and above a predetermined temperature range of -246 ° C of the enthalpy of condensation, such as -196 ° C.

As shown in FIG. 5, step c) sequentially passes the mixed gas through the freezing liquefaction tank, the auxiliary purification tank, and the freeze-solidification tank.

After the mixed gas is sent to the refrigerating liquefaction tank, the crucible will be liquefied, and the remaining gas will enter the auxiliary purification tank; at this time, due to the vapor pressure, a small amount of helium gas will still enter the auxiliary purification tank in the remaining gas; The liquid in the liquefaction tank is the purified hydrazine.

After the gas enters the auxiliary purification tank, the helium will be solidified, and the argon will be liquefied, and the remaining gas will enter the freezing and solidifying tank; of course, the remaining gas at this time also contains a small amount of argon; The liquid is the purified argon.

After the gas enters the freeze-cure tank, the argon is solidified and the helium is still in a gaseous state; the gas discharged from the freeze-cure tank is the purified helium.

Step d) Stop feeding the mixed gas.

Step d1) using a vacuuming method and/or feeding helium gas to the auxiliary purification tank; and using a vacuuming method and/or feeding argon gas to the freezing and solidifying tank.

As shown in FIG. 6, step e) respectively melts or vaporizes the solid matter in the auxiliary purification tank and the freeze-solidification tank, and then discharges the purified substance argon and argon, respectively.

The above embodiments of the present invention are provided for convenience of explanation only. When the meaning of the case cannot be limited, the various transformation designs according to the scope of the listed patent application should be included in the patent scope of the present application.

Claims (8)

A gas recovery and purification process comprising the steps of: a) preparing a refrigerant, a mixed gas, a refrigerating liquefaction tank and a freezing and solidifying tank; b) using a refrigerant to maintain the refrigerating liquefaction tank within a predetermined temperature range, so that After the mixed gas passes through the refrigerating liquefaction tank, at least one substance is liquefied; and the temperature in the freezing and solidifying tank is maintained within a predetermined temperature range by using a refrigerant, so that when the mixed gas passes through the freezing and solidifying tank, the large Part of the material will be solidified, leaving only one substance in a gaseous state; c) sequentially passing the mixed gas through the refrigerating liquefaction tank, the freezing and solidifying tank for refrigerating and solidifying; discharging the gaseous substance in the freezing and solidifying tank That is, the purified substance; the liquid substance discharged from the refrigerating liquefaction tank is the purified substance. The process for recovering and purifying the gas according to claim 1, wherein the step a) further comprises the following steps: a1) discharging the refrigerating liquefaction tank and the freezing and solidifying tank, thereby draining the gas therein; Including: using a vacuuming method and/or feeding the same gas as the gas having the lowest freezing point in the mixed gas. The process for recovering and purifying the gas according to claim 1, wherein the step c) further comprises the steps of: d) stopping the feeding of the mixed gas; e) melting or vaporizing the solid matter in the freezing and solidifying tank, and discharging; This is the purified substance. The process for recovering and purifying the gas according to claim 3, wherein the step d) further comprises the following steps: d1) draining the freeze-cure tank The segment is used to drain the gas therein; the means of evacuation includes: using a vacuum method and/or feeding the same gas as the solid matter therein. The process for recovering and purifying the gas according to claim 1, wherein the refrigerant is liquid nitrogen; the solidification point of all the substances in the mixed gas is above -196 ° C, or only one substance has a freezing point below -196 ° C. The process for recovering and purifying the gas according to claim 1, wherein the step a) is provided with one or two auxiliary purification tanks between the freezing liquefaction tank and the freezing and solidifying tank; and the auxiliary purification tank is connected in series to the freezing liquefaction tank. Between the freezing and solidifying tank; the step b) is to maintain the temperature of the auxiliary purification tank within a predetermined temperature range by using a refrigerant, so that the substance liquefied in the previous purification tank is solidified in the auxiliary purification tank, and One of the remaining gases is liquefied. The process for recovering and purifying the gas according to claim 6, wherein the refrigerating liquefaction tank, the freezing and solidifying tank and the auxiliary purification tank respectively have a sandwich space; the refrigerant is sent into the interlayer space of the purification tank; the purification tank A frozen piece is welded to the inner wall to increase the frozen area. The process for recovering and purifying the gas according to claim 1, wherein the step c) is to send the mixed gas to the refrigerating liquefaction tank and the freezing and solidifying tank at a predetermined flow rate, so that the mixed gas has sufficient freezing in the purification tanks. Residence time.