JP2000088455A - Method and apparatus for recovering and refining argon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently recover a high purity argon gas from exhaust gas discharged from a silicon monocrystal producing furnace. SOLUTION: From the exhaust gases discharged from a monocrystal producing furnace 1, solid particles of the exhaust gases are removed by a dust collector 2, and then an oil content thereof is removed by an oil-removing cylinder 4 and an oil-removing filter 5. Then, hydrogen is added thereto and sent to a catalyst cylinder 7, where oxygen is converted into water, and then moisture and carbon dioxide are removed in an adsorbing cylinder 8. Further, the remaining gases are supplied to a fractionating column comprising a high pressure column 9, and a low pressure column 11. In the high pressure column, a component of a higher boiling temperature than that of argon is fractionated, and in the low pressure column, a component of a lower boiling temperature than that of argon is fractionated. Argon gas of high purity is extracted from the low pressure column to be recycled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for recovering and purifying argon, and more particularly to a semiconductor manufacturing method such as a single crystal manufacturing furnace for manufacturing a single crystal such as a silicon single crystal used as a base material of a semiconductor. The present invention relates to a method and an apparatus for recovering and purifying high-purity argon from an exhaust gas containing argon discharged from the apparatus.

[0002]

2. Description of the Related Art Since argon gas has an inert property, it is widely used in various industrial fields as a shielding gas for welding, an atmosphere gas for heat treatment of metals, and the like. In recent years, in a single crystal manufacturing furnace for manufacturing a single crystal such as a silicon single crystal used as a base material of a semiconductor, a high purity (9
9.999% by volume) of argon gas is used as the atmosphere gas in the furnace. Therefore, an exhaust gas containing argon as a main component is discharged from such a single crystal production furnace, and the composition of the exhaust gas is such that 99 to 99.9% by volume of argon is used as an atmosphere gas of the furnace. As a result, not only dust such as silicon oxide, silicon dioxide, and carbon is mixed and entrained, but also oil, moisture, carbon monoxide, carbon dioxide,
Various components such as oxygen, hydrogen, nitrogen, and hydrocarbons are mixed as impurities, though in trace amounts.

Various methods for recovering and reusing argon from exhaust gas of such components have been proposed in the past, for example, Japanese Patent Application Laid-Open Nos. 63-189774, 1-230975 and 1-230975. JP-A-2-272288, JP-A-2-282682, JP-A-3-398
No. 86, Japanese Patent Publication No. 4-123393, Japanese Patent Publication 5-
No. 29834, JP-A-5-256570, JP-A-9-72656 and the like.

[0004]

However, in the conventional method, it is difficult to efficiently remove other types of impurities as described above, and it has not been said that there is still a sufficient purification method. Therefore, the present invention provides a semiconductor manufacturing apparatus such as a single crystal manufacturing furnace containing argon as a main component and various impurity components such as dust, oil, moisture, carbon monoxide, carbon dioxide, oxygen, hydrogen, nitrogen, and hydrocarbons. It is an object of the present invention to provide an argon purification method and apparatus capable of efficiently recovering high-purity argon gas from exhaust gas from wastewater.

[0005]

According to a first aspect of the present invention, there is provided a method according to the first aspect, comprising argon as a main component, solids such as dust, oil, moisture, carbon monoxide, carbon dioxide, oxygen, hydrogen, A method for recovering and purifying argon in an exhaust gas from a semiconductor manufacturing apparatus such as a single crystal manufacturing furnace containing nitrogen, hydrocarbon, or the like as an impurity, wherein the step of removing solids such as the dust and the step of compressing the exhaust gas A step of removing the oil component; a step of adding hydrogen in excess of a stoichiometric amount necessary for the reaction with the oxygen in the exhaust gas to convert oxygen into water by a catalytic reaction; An adsorption removal step of continuously switching the water and the water and carbon dioxide converted in the catalytic reaction step between the adsorption step and the regeneration step by using a plurality of adsorption columns to continuously adsorb and remove the exhaust gas, and liquefying the exhaust gas passing through each of the above steps. Low temperature obtained by distillation A high-boiling component concentrate obtained by condensing a high-boiling component having a higher boiling point than argon from a flue gas by liquefying the cooled exhaust gas, and a crude argon condensing a low-boiling component having a lower boiling point than argon. A high-boiling-point component separation step of separating into a gas and a high-purity argon and a low-boiling point component having a lower boiling point than argon are concentrated from the crude argon gas by liquefying and rectifying the crude argon gas separated in the high-boiling point component separation step. A low-boiling-point component separation step of separating the waste gas into waste gas; and a step of recovering the high-purity argon obtained in the low-boiling-point component separation step by raising the temperature by heat exchange with the exhaust gas.

According to a second aspect of the present invention, in the method of the first aspect, the temperature of the exhaust gas introduced into the catalytic reaction step is adjusted to a temperature at which hydrogen and carbon monoxide in the exhaust gas do not react.

In the method of claim 1, the exhaust gas derived from the adsorption and removal step and the high-boiling-point component separation are used as the regeneration gas in the regeneration step of the adsorption column in the adsorption and removal step. At least one of a gas obtained by vaporizing the high-boiling component concentrated liquid separated in the step and a waste gas separated in the low-boiling component separating step is used.

The method of claim 4 is characterized in that, in the method of claim 1, the high-boiling component separation step and the low-boiling component separation step are performed by a double rectification column including a high-pressure column, a main condenser and a low-pressure column. The high-boiling-point component separation step is performed by introducing the exhaust gas into the middle stage of the column, liquefying and rectifying the gas by liquid-gas contact between the rising gas generated in the bottom evaporator and the reflux liquid generated in the main condenser. The high-boiling-point component separation step is performed in the high-pressure column that derives the high-boiling component concentrate from the bottom and the crude argon gas from the top, and the low-boiling-point component separation step converts the crude argon gas separated in the high-pressure column into a middle column. Liquefied and rectified by gas-liquid contact between the rising gas generated in the main condenser and the reflux liquid generated in the top condenser, leading the high-purity argon from the bottom of the column, and leading the waste gas from the top of the column In the low pressure tower It is.

According to a fifth aspect of the present invention, in the method of the fourth aspect, compressed nitrogen gas compressed by a circulating compressor is introduced into the bottom evaporator to vaporize the bottom liquid of the high-pressure column and rise. A step of generating a gas, and a step of reducing the pressure of liquefied nitrogen liquefied in the step of generating a rising gas in the high-pressure column, introducing the reduced pressure into the top condenser, and liquefying the top gas of the low-pressure column to generate a reflux liquid. Returning the compressed nitrogen gas to the circulating compressor to compress the nitrogen gas vaporized in the step of generating the reflux liquid of the low-pressure column; and supplying the compressed nitrogen gas to the step of generating the ascending gas again to circulate the same. A nitrogen circulation step.

[0010] According to a sixth aspect of the present invention, in the method of the fifth aspect, liquefied nitrogen introduced from the outside is added to the liquefied nitrogen in the nitrogen circulating step to perform cold supply.

According to a seventh aspect of the present invention, in the method of the fifth aspect, the cold supply is performed at a low temperature obtained by expanding a part of the compressed nitrogen gas in the nitrogen circulation step.

The method according to claim 8 is the method according to claim 5, wherein nitrogen gas from the nitrogen circulation step is used as a regeneration gas in the regeneration step of the adsorption column in the adsorption removal step.

A ninth aspect of the present invention is directed to the production of a single crystal comprising argon as a main component and solids such as dust, oil, moisture, carbon monoxide, carbon dioxide oxygen, hydrogen, nitrogen, and hydrocarbons as impurities. A device for collecting and purifying argon in exhaust gas from a semiconductor manufacturing device such as a dust collecting device for removing solids such as the dust, a compression device for compressing the exhaust gas to a required pressure, and the oil component. Oil removing means for removing, catalytic reaction means for adding hydrogen to the exhaust gas and reacting with oxygen in the exhaust gas to convert it to water, and using a plurality of adsorption columns to alternately switch an adsorption step and a regeneration step to the catalyst. Adsorption removing means for continuously absorbing and removing the water and carbon dioxide contained in the water and the exhaust gas converted by the reaction means,
A main heat exchanger that exchanges heat with the low-temperature return fluid obtained by the liquefaction rectification to cool the exhaust gas, and a liquefied rectification of the low-temperature exhaust gas that is cooled by the main heat exchanger and contains the remaining impurities and has a boiling point higher than that of argon A high-pressure column that separates a high-boiling component concentrate containing a high-boiling component and a crude argon gas containing a low-boiling component having a boiling point lower than that of argon. A low-pressure column for separating pure argon and low-boiling components having a lower boiling point than argon into a concentrated waste gas; heat exchange between a top gas of the high-pressure column and a bottom solution of the low-pressure column; A double rectification column including a main condenser for generating a rising gas of a low pressure column, and a product recovery path for collecting high purity argon separated by the low pressure column of the double rectification column through the main heat exchanger are provided. .

According to a tenth aspect of the present invention, in the device of the ninth aspect, the catalyst reaction means includes a heater, a catalyst tube, an exhaust gas path, and an added hydrogen path, and connects the heater to the catalyst tube. The catalyst reaction temperature control means includes a temperature detector provided in the exhaust gas path, and a heating capacity controller for controlling a heating capacity of the heater based on a signal from the temperature detector.

An apparatus according to an eleventh aspect is the apparatus according to the ninth aspect, wherein a waste gas separated at the top of the low pressure column of the double rectification column is extracted through the main heat exchanger, and the waste gas is extracted from the path. A path for supplying waste gas as a regeneration gas for the adsorption cylinder in the adsorption and removal means is provided.

The apparatus according to claim 12 is the apparatus according to claim 9, wherein a path for extracting the high-boiling component concentrate separated at the bottom of the high-pressure column of the double rectification column, and a high-boiling component concentrated for extraction from the path. A means for evaporating the liquid and raising the temperature, and a path for supplying the high-boiling component vaporized gas derived from the means as a regeneration gas for the adsorption column in the adsorption and removal means are provided.

In the apparatus according to a thirteenth aspect, in the apparatus according to the twelfth aspect, the means for vaporizing the high-boiling-point component concentrate and raising the temperature is the main heat exchanger.

The apparatus according to claim 14 is the apparatus according to claim 9, wherein a circulating compressor for compressing the circulating nitrogen gas and a bottom liquid of the high-pressure column using the compressed nitrogen gas compressed by the circulating compressor as a heating source. A bottom evaporator for producing ascending gas by evaporating the gas, a pressure reducing valve for reducing the liquefied nitrogen liquefied by the bottom evaporator, and a top of the low pressure column using the liquefied nitrogen depressurized by the pressure reducing valve as a cold source. There is provided a nitrogen circulation path having a top condenser for condensing gas to generate a reflux liquid, and a path for circulating nitrogen gas vaporized by the top condenser to the suction side of the circulating compressor.

According to a fifteenth aspect of the present invention, in the device of the fourteenth aspect, a refrigeration supply path for introducing liquefied refrigeration nitrogen for cooling from the outside is connected to the liquefied nitrogen path in the nitrogen circulation path.

A device according to a sixteenth aspect of the present invention is the device according to the fourteenth aspect, further comprising a path for supplying the nitrogen gas in the nitrogen circulation path as a regeneration gas for the adsorption column in the adsorption and removal means.

Further, the device according to claim 17 is the device according to claim 14.
In the apparatus, an expansion turbine that introduces compressed nitrogen gas on the discharge side of the circulating compressor in the nitrogen circulation path to adiabatically expand to generate cold, and that the cold generated in the expansion turbine is recovered and then circulated in the nitrogen circulation path. It has a cold generation path consisting of a path returning to the suction side of the compressor.

[0022]

1 and 2 show an embodiment of the present invention. FIG. 1 is a system diagram showing a front part, and FIG. 2 is a system diagram showing a rear part. This argon purifier
It is for treating argon-containing exhaust gas discharged from a single-crystal production furnace, for example, a silicon single-crystal production furnace, to recover argon with high purity. In the former part shown in FIG. A dust collector 2 which is a dust collecting means for removing solids such as dust in the exhaust gas, an exhaust gas compressor 3 which is a compression means for compressing the exhaust gas to a required pressure, and an oil which is an oil removing means for removing a fraction. A removal cylinder 4 and an oil removal filter 5,
A preheater 23 and a heater 2 which are catalytic reaction means for adding hydrogen to the exhaust gas to convert oxygen in the exhaust gas into water by a catalytic reaction.
4, an additional hydrogen path 6 and a catalyst cylinder 7, and a plurality of adsorption cylinders 8 filled with an adsorbent such as zeolite, which is an adsorption and removal means for adsorbing and removing moisture and carbon dioxide. In the latter part shown in FIG. 2, effluent is introduced to perform liquefaction rectification to separate into a high-boiling-point component concentrated liquid in which impurities having a higher boiling point than argon are concentrated and a crude argon gas in which low-boiling impurities are concentrated. Double rectification including a high-pressure column 9, a main condenser 10, and a low-pressure column 11 for introducing the crude argon gas to perform liquefaction rectification to separate high-purity argon and waste gas in which low-boiling-point impurities are concentrated. Circulation compression for circulating and supplying nitrogen as a heating source of a column and a bottom evaporator 12 for vaporizing a bottom liquid of the high pressure column 9 and a cooling source of a top condenser 13 for liquefying a top gas of the low pressure column 11. A nitrogen circulation path and the like constituted by the machine 14 and the like are provided.

First, in FIG. 1, the exhaust gas from the single crystal production furnace 1, for example, 150 mg / Nm ^{3 of} solid dust, 100 ppm by volume of hydrogen, 1500 ppm by volume of oxygen, 3000 ppm by volume of carbon monoxide, 200 ppm by volume of carbon dioxide,
Nitrogen 7000 volume ppm, hydrocarbon (methane conversion) 50
Exhaust gas 100 Nm ³ / h containing impurities consisting of ppm by volume, 10 ppm by volume of oil, and a saturated amount of water is compressed to about lkPaG by a blower 15 provided as required from the operating pressure of the single crystal production furnace 1. It is stored in the gas holder 17 via the path 16. Exhaust gas in the gas holder 17 is introduced into the dust collector 2 through the path 18, and solid dust such as silicon oxide, silicon dioxide, and carbon contained in the exhaust gas is removed and led out to the path 19.

Next, the exhaust gas is discharged by the exhaust gas compressor 3.
The product is compressed to the pressure of high-purity argon or the pressure required for processing in the subsequent steps. For example, in order to obtain a product high-purity argon with a pressure of 490 kPaG, the exhaust gas must be 730 kPaG.
Compress to PaG. The compressed exhaust gas is subjected to removal of heat of compression by an aftercooler 20, introduced into an oil removal cylinder 4 through a path 21, and oil is removed by activated carbon or the like charged in the cylinder. And the residual oil is removed therefrom. In addition,
Only one of the oil removing cylinder 4 and the oil removing filter 5 may be provided according to the situation of the oil component in the exhaust gas.

The exhaust gas from which dust and oil have been removed is passed through a passage 22 through a preheater 23 and a heater 2 which constitute a catalytic reaction means.
4, is heated to a predetermined temperature, for example, 100 to 300 ° C., is led out to a path 25, is mixed with hydrogen added from a path 26 of an additional hydrogen path 6, and is introduced into the catalyst cylinder 7. The catalyst tube 7 is filled with a catalyst such as palladium or platinum, and the reaction between the oxygen in the exhaust gas introduced into the catalyst tube 7 and the added hydrogen is promoted to convert the oxygen content into water. To remove oxygen from the exhaust gas.

The reaction temperature of this catalytic reaction is about 3
When the temperature rises to 50 ° C. or higher, carbon monoxide and hydrogen in the exhaust gas react with each other to generate hydrocarbons (methane), and the amount of hydrocarbons increases. However, there has been a problem that the reaction cannot be sufficiently removed. For this reason, in this recovery and purification apparatus, a temperature detector is provided in an exhaust gas path 25 which leads out the heater 24 and is introduced into the catalyst tube 7, and the heating capacity of the heater 24 is reduced by the temperature detector and a signal from the temperature detector. A catalyst reaction temperature control means including a temperature controller (TIC) 24a for controlling a heating capacity controller to be adjusted is provided, and the reaction temperature of the catalyst tube 7 is set to a temperature range (300 ° C. or lower) where carbon monoxide and hydrogen do not react. It is configured to hold.

The amount of hydrogen introduced and added from the addition hydrogen passage 6 is set to be an amount exceeding the stoichiometric amount required to convert oxygen in the exhaust gas flowing through the exhaust gas passage 22 into water. It is determined in consideration of the oxygen content and the hydrogen content contained therein. For example, an oxygen concentration meter (QOI) 27 and a flow meter (FI) 28 are provided in the path 22 to measure the amount of oxygen in the exhaust gas toward the catalyst cylinder 7, and to supply hydrogen to the exhaust gas path 29 from the catalyst cylinder 7. Densitometer (QH
I) Providing 30 to measure the amount of remaining hydrogen, calculating the amount of added hydrogen according to the measured amount of oxygen and the amount of hydrogen, and using the signal of the calculation result as the hydrogen flow rate provided in the added hydrogen path 6 By adjusting the degree of opening of the additional hydrogen control valve 31a by sending it to the meter (FIC) 31, an appropriate amount of hydrogen can be added, and the oxygen content in the exhaust gas can be reliably and effectively removed.

The exhaust gas from which oxygen has been removed by converting oxygen to water in the catalyst tube 7 is recovered in heat by the preheater 23, led out to the path 29, and cooled by the cooling device 32 to about 10 ° C. Is introduced into the adsorption cylinder 8 during the adsorption step which constitutes the adsorption removing means. The cooling device 32 is provided to improve the adsorption efficiency of the adsorption column 8 by cooling the exhaust gas to reduce the size of the adsorption column 8, but may be omitted depending on the situation.

The adsorption and removal means constituted by using a plurality of adsorption columns 8 comprises an adsorption step of adsorbing and removing water and carbon dioxide by an adsorbent filled in the adsorption column 8, and a method of removing water and carbon adsorbed by the adsorbent. The regeneration step for desorbing carbon dioxide is performed by sequentially switching. The switching step provided before and after the adsorption column 8 is opened and closed in a predetermined order, so that the adsorption step and the regeneration step can be switched. Inside the adsorption tube 8,
Zeolite or the like is filled as an adsorbent for adsorbing and removing moisture and carbon dioxide. By passing exhaust gas through the adsorbent, moisture and carbon dioxide in the exhaust gas are adsorbed and removed.

In the regeneration step of the adsorption column 8, the regeneration gas, for example, nitrogen gas introduced from the passage 33 is supplied to the regeneration heater 34.
And heating to introduce into the adsorption column 8 to desorb water and carbon dioxide from the adsorbent, and then stop the regenerator 34 to cool the adsorbent. There may be a charging operation for increasing the pressure of the adsorption cylinder 8 to the pressure of the adsorption step. In addition, as the regeneration gas, a part of the exhaust gas that is led out of the adsorption means after the adsorption step can be used by branching to a path 33a indicated by a broken line in FIG.

As described above, solids such as dust, oil, oxygen, moisture, carbon dioxide, etc. are removed through the dust collector 2, the oil removing cylinder 4, the oil removing filter 5, the catalyst cylinder 7, and the adsorption cylinder 8. The discharged exhaust gas is sent to a rear part shown in FIG. Exhaust gas 98Nm ³ / h passing through this route 35 is
50 vol ppm of methane which is a high boiling component having a higher boiling point than argon, 7000 vol ppm of nitrogen which is a low boiling component having a lower boiling point than argon, and 3000 vol pp of carbon monoxide
m, hydrogen 100 vol. p containing 1 vol.
pm, and the double rectification column for liquefying these high-boiling and low-boiling components, the main heat exchanger 36, the bottom evaporator 12, and the top condensate necessary for performing liquefaction rectification. It is introduced into a cold box 38 in which low-temperature equipment such as the cooler 13 and the subcooler 37 are stored.

The exhaust gas flowing into the cold box 38 from the path 35 exchanges heat with a low-temperature return gas such as high-purity argon gas in the main heat exchanger 36 and is cooled to a predetermined temperature. It is introduced into the middle stage of the high pressure tower 9 constituting the tower. The exhaust gas introduced into the high-pressure column 9 is rectified by gas-liquid contact between the gas rising from the bottom evaporator 12 at the bottom of the column and the reflux liquid flowing down from the main condenser 10 at the top of the column, and has a high boiling point component. A high-boiling component concentrate obtained by condensing a certain methane is separated at the bottom of the column, and a crude argon gas which concentrates a low-boiling component and contains substantially no high-boiling component is separated at the top of the column.

Separated at the bottom of the high pressure tower 9 and removed from the path 40
5Nm of high boiling component concentrate ^Three/ H is methane 9
Liquefied argon containing 80 ppm by volume
Argon uses air or other suitable fluid as a heating source
Evaporator 41 is a means for evaporating and raising the temperature.
After that, it is released from the path 42 to the atmosphere. Also vaporize
Using the main heat exchanger 36 as a means for raising the temperature
In this case, the configuration is simplified. In addition, vaporization temperature rise
The adsorbed gas, if necessary,
8 can be used as a regeneration gas.

On the other hand, the crude argon gas 93 Nm ³ / h, which is separated at the top of the high pressure column 9 and concentrated at a low boiling point component withdrawn from the top of the high pressure tower 9 through the passage 43, is supplied with 7400 vol.
m, argon gas containing 3200 ppm by volume of carbon monoxide and 1200 ppm by volume of hydrogen.
3a is led to the main condenser 10 and exchanges heat with high-purity liquefied argon, which is the bottom liquid of the low-pressure column 11, to generate ascending gas in the low-pressure column 11 and to liquefy itself to form the reflux liquid of the high-pressure column 9. And is returned to the top of the high pressure tower 9 from the path 43b.

The remaining crude argon gas having the above composition extracted into the passage 43 is reduced in pressure to 528 kPaG by the pressure reducing valve 44, then introduced into the middle stage of the low pressure column 11, and passed through the main condenser 10 at the bottom of the column. The liquefied rectification is further performed by gas-liquid contact between the generated ascending gas and the reflux liquid generated in the top condenser 13 at the top of the tower, and high-purity liquefied argon at the bottom of the tower and low-boiling impurities at the top of the tower are concentrated. Separated from gas.

The waste gas separated at the top of the low-pressure column 11 and extracted from the passage 45 is composed of 14% by volume of nitrogen and 6% of carbon monoxide.
% Of hydrogen, 22% by volume of hydrogen, and 58% by volume of argon, of which 5 Nm ³ / h is partly guided to the main heat exchanger 36 from the passage 45 to cool the exhaust gas introduced from the passage 35. As a result, the temperature rises and is discharged from the cold box 38 via the path 46. This exhaust gas can be used as a regeneration gas for the adsorption column 8 of the adsorption and removal means as needed.

The remaining waste gas having the above-mentioned composition extracted through the passage 45 is introduced into the top condenser 13 through the passage 45a and liquefied by exchanging heat with the cooling source fluid. To the top of the low pressure column 11.

On the other hand, the high-purity liquefied argon separated at the bottom of the low-pressure column 11 undergoes heat exchange with the crude argon gas at the top of the high-pressure column 9 in the main condenser 10 as described above, and is evaporated and vaporized to become a rising gas. The impurities are high-purity argon gas of 1 volume ppm or less of nitrogen, 1 volume ppm or less of oxygen, 1 volume ppm or less of carbon monoxide, 1 volume ppm or less of carbon dioxide, 1 volume ppm or less of hydrogen, and 1 volume ppm or less of methane. A portion of 88 Nm ³ / h is led from the lower part of the tower to a path 47 constituting a product recovery path, and is led to the main heat exchanger 36,
The temperature of the exhaust gas introduced from the passage 35 is increased by cooling, and the exhaust gas is recovered as high-purity argon gas through a passage 48 and a valve 49 constituting an end portion of the product collection passage, and supplied to the single crystal production furnace 1 again. Is done.

As the heating source of the bottom evaporator 12 and the cooling source of the top condenser 13, nitrogen circulated by circulating compressor 14 is used. In the circulation compressor 14,
650 Nm ³ / compressed nitrogen gas compressed to 72 MPaG
h is introduced into the cold box 38 via the path 50 and exchanges heat with the low-temperature return gas in the main heat exchanger 36 to be cooled to a predetermined temperature.
2 is introduced as a heating source fluid. The compressed nitrogen gas introduced into the bottom evaporator 12 exchanges heat with the bottom liquid of the high-pressure column 9 and evaporates and vaporizes the bottom liquid to generate ascending gas. It becomes nitrogen. The liquefied nitrogen generated in the bottom evaporator 12 is led out of the passage 51 and further cooled by the supercooler 37, and then 700 kP by the pressure reducing valve 52.
The pressure is reduced to aG and introduced into the top condenser 13 from the passage 54 as a cooling source fluid. Further, in order to supply the cold against the heat entering the cold box 38, a cold supply path 5 is provided.
Liquefied nitrogen 20 Nm ³ / h from outside injected via
Are joined to the path 54.

The liquefied nitrogen introduced as a cooling source fluid into the top condenser 13 condenses and liquefies the gas at the top of the low-pressure column 11 to generate a reflux liquid, and evaporates itself to become nitrogen gas again. The nitrogen gas is led from the top condenser 13 to the path 55, passes through the subcooler 37 and the path 56, and is heated by cooling the exhaust gas in the main heat exchanger 36, and the cold box 38 is passed through the path 57. And returned to the circulating compressor 14 again to circulate through the path (nitrogen circulation path). Insufficient nitrogen gas at the time of startup is supplied from a valve 58 provided on a path branched from the suction side path 57 of the circulating compressor 14. In addition, the injected liquefied nitrogen causes excess nitrogen gas 20 Nm ^{3 in the} nitrogen circulation path.
/ H is discharged from a valve 59 of a path branched from the suction side path 57 of the circulating compressor. This nitrogen gas can be used as a regeneration gas for the adsorption column 8 of the adsorption and removal means as needed.

As described above, according to the method and apparatus for recovering and purifying argon of the present embodiment, oxygen as an impurity having a boiling point close to that of argon and difficult to separate and remove by liquefied rectification is obtained by adding hydrogen prior to liquefied rectification. By removing by a catalytic reaction, high boiling components or low boiling components as other impurities can be efficiently separated by liquefied rectification.

Further, in the catalytic reaction step, the amount of hydrogen reacting with oxygen is stabilized while the amount of hydrogen reacting with oxygen is stabilized by adjusting the temperature of the catalytic reaction to a temperature at which hydrogen in the waste gas does not react with carbon monoxide. , And oxygen as impurities can be reliably and efficiently removed, and efficiently removed by liquefaction rectification without increasing hydrocarbons as impurities.

In separating and removing high-boiling components and low-boiling components as impurities by liquefaction rectification, the high-boiling components are separated and removed first, and then the low-boiling components are separated and removed. Compared to the opposite case,
Since the low-boiling-point component content in the gas separated at the top of the high-pressure column can be small, the pressure difference between the high-pressure column and the low-pressure column in the heat exchange of the main condenser can be reduced, and the low-pressure column without lowering the product yield. , The high-purity argon of the product can be extracted directly by the pressure supplied to the single crystal production furnace. Therefore, there is no need to provide a product argon compressor, or the compression power of the exhaust gas compressor can be reduced.

Further, a gas obtained by vaporizing a high-boiling-point impurity concentrated liquid separated or removed by liquefaction rectification, a waste gas containing concentrated low-boiling-point components, or a nitrogen gas vaporized from liquefied nitrogen introduced for cold supply is adsorbed and removed. By utilizing the gas for regeneration of the adsorption column, the equipment configuration can be simplified, and equipment costs and operating costs can be reduced.

FIG. 3 is a system diagram showing another embodiment of the latter part of the present invention. Since the former part can be formed in the same manner as the embodiment shown in FIG. 1, illustration and description are omitted. The same components as those in the embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, instead of supplying liquefied nitrogen from the outside as a cold supply, a cold generation path is provided which adiabatically expands the compressed nitrogen gas in the nitrogen circulation path by the expansion turbine 62 to generate cold. In the cold that occurred in the outbreak route,
It is configured to supply cold.

That is, similarly to the embodiment shown in FIG. 2, the compressed nitrogen gas compressed to a required pressure by the circulation compressor 14 is:
After the heat of compression is removed, the heat is introduced into the main heat exchanger 36 from the path 50, exchanges heat with the low-temperature return gas, and is cooled.
Is introduced into the bottom evaporator 12 as a heating source, and is liquefied by heat exchange with the column bottom liquid to become liquefied nitrogen, which is led out to the path 51. The liquefied nitrogen passes through the subcooler 37 and is decompressed by the pressure reducing valve 52 and introduced into the top condenser 13 as a cooling source.
The heat exchange with the top gas of No. 1 evaporates and evaporates into nitrogen gas, and the path 55, the subcooler 37, the path 56, the main heat exchanger 36
Through the passage 57 and returned to the suction side of the circulating compressor 14 to circulate.

Then, a part of the compressed nitrogen gas is branched and led out to a path 61 constituting a cold generation path and is introduced into an expansion turbine 62 while being cooled by the main heat exchanger 36.
The compressed nitrogen gas introduced into the expansion turbine 62 is adiabatically expanded to lower the pressure and lower the temperature to generate cold, and from a path 63 constituting a cold generation path, is vaporized by the top condenser 13 and vaporized by the circulation compressor 14. It is joined to the path 56 returning to the suction side and guided to the main heat exchanger 36.

The generated nitrogen gas for maintaining the cold is led to the main heat exchanger 36, where the cold is recovered by exchanging heat with the exhaust gas and the compressed nitrogen gas, and the temperature is raised. And circulate through the nitrogen circulation path.

As described above, in this embodiment, it is necessary to inject liquefied nitrogen for cold supply from the outside by arranging such that the cold gas generated by expanding the nitrogen gas inside the device is supplied. Because there is no operation management, it becomes easy.

[0051]

As described above, claims 1 and 9
According to the described method and apparatus, the main component is argon discharged from a semiconductor manufacturing apparatus such as a single crystal manufacturing furnace,
High-purity argon gas can be efficiently recovered from waste gas containing impurities such as dust, oil, moisture, carbon monoxide, and oxygen. Further, since oxygen as an impurity is removed by a hydrogenation catalytic reaction prior to liquefaction rectification, liquefaction rectification of a component having a higher boiling point or a component having a lower boiling point than argon in the subsequent stage can be performed more efficiently.

According to the method and the apparatus according to the second and tenth aspects, the reaction temperature in the catalytic reaction step can be adjusted to a temperature at which the hydrogen and carbon monoxide in the waste gas do not react, and the reaction temperature with the oxygen can be controlled. In addition to stabilizing the amount of hydrogen to be removed, oxygen can be reliably removed, and generation of hydrocarbons can be suppressed.

According to the method described in the third and eighth aspects and the apparatus described in the eleventh, twelfth, thirteenth, and sixteenth aspects, various types of unnecessary gas in the refining process can be used for the regeneration gas in the adsorption cylinder of the adsorption removing means. Gas can be used, equipment can be simplified, and operating costs can be reduced.

According to the method of claim 4, since the high-boiling components of impurities are removed by the high-pressure column and the low-boiling components are removed by the low-pressure column, the product high-purity argon can be prepared at a relatively high level. Pressure can be obtained, and it is not necessary to provide a product argon compressor, and the compression power of the exhaust gas compressor can be reduced.

According to the method described in claim 5 and the apparatus described in claim 14, a nitrogen circulation path is provided, and the circulating nitrogen is used as a heating source for the high-pressure column and a cooling source for the low-pressure column. Can reduce the supply of cold energy from
Operation costs can be reduced.

Further, according to the method described in claim 6 and the apparatus described in claim 15, refrigeration that is insufficient in the nitrogen circulation path can be replenished from the outside as necessary, and stable operation can be continued.

Furthermore, according to the method described in claim 7 and the device described in claim 17, it is possible to cover the cold required for the operation in the device, and it is not necessary to supply the cold from the outside. Becomes easier.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a front part of an embodiment of the apparatus of the present invention.

FIG. 2 is a configuration diagram showing a rear part of an embodiment of the apparatus of the present invention.

FIG. 3 is a configuration diagram showing a rear part of another embodiment of the apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single crystal manufacturing furnace, 2 ... Dust collector, 3 ... Exhaust gas compressor, 4
... oil removal cylinder, 5 ... oil removal filter, 6 ... added hydrogen path, 7 ... catalyst cylinder, 8 ... adsorption cylinder, 9 ... high pressure tower, 10 ... main condenser, 11 ... low pressure tower, 12 ... bottom evaporator, 13: Top condenser, 14: Circulating compressor, 36: Main heat exchanger, 62: Expansion turbine

Claims (17)

[Claims] 1. A semiconductor manufacturing apparatus such as a single crystal manufacturing furnace containing argon as a main component and containing solids such as dust, oil, water, carbon monoxide, carbon dioxide, oxygen, hydrogen, nitrogen, and hydrocarbons as impurities. A method for recovering and purifying argon in exhaust gas from a process, comprising the steps of removing solids such as dust, compressing the exhaust gas, removing the oil component, and reacting oxygen in the exhaust gas. A catalytic reaction step of adding oxygen in excess of the stoichiometric amount necessary to convert oxygen to water by a catalytic reaction, and the water converted in the catalytic reaction step, the water and the carbon dioxide in a plurality of adsorption columns. An adsorption removal step for continuously performing adsorption removal by alternately switching the adsorption step and the regeneration step, a step of cooling the exhaust gas having passed through each of the above steps with a low-temperature return gas obtained by liquefaction rectification, and Liquefaction rectification A high-boiling-point component separation step of separating a high-boiling-point component concentrated liquid having a higher boiling point than argon from the exhaust gas and a crude argon gas having a low-boiling-point component having a lower boiling point than argon concentrated. A low-boiling-point component separation step of liquefying the crude argon gas separated in the separation step to separate high-purity argon and low-boiling components having a lower boiling point than argon from the crude argon gas into a concentrated waste gas; And recovering the high-purity argon obtained in the component separation step by raising the temperature by heat exchange with the exhaust gas. 2. The method according to claim 1, wherein in the catalytic reaction step, the temperature of the exhaust gas introduced into the catalytic reaction step is adjusted to a temperature at which hydrogen and carbon monoxide in the exhaust gas do not react. Purification method. 3. A gas obtained by vaporizing an exhaust gas derived from the adsorption removal process and a high-boiling component concentrate separated in the high-boiling component separation process as a regeneration gas in the regeneration process of the adsorption column in the adsorption and removal process. At least one of the separated gas and the waste gas separated in the low boiling point component separation step.
2. The method for recovering and purifying argon according to claim 1, wherein two gases are used. 4. The high-boiling component separation step and the low-boiling component separation step are performed by a double rectification column including a high-pressure column, a main condenser, and a low-pressure column. Liquefied and rectified by gas-liquid contact between the ascending gas generated in the bottom evaporator introduced in the bottom evaporator and the reflux liquid generated in the main condenser, and the high boiling component concentrated liquid is derived from the bottom of the column and the top of the column. The low-boiling-point component separation step is performed in the high-pressure column that derives the crude argon gas from the high-pressure column. The liquefaction and rectification by airtight contact with a reflux liquid generated in a vessel, the high-purity argon is led out from the lower part of the column, and the waste gas is led out from the top part of the column in the low-pressure column.
The method for recovering and purifying argon described above. 5. A step of introducing a compressed nitrogen gas compressed by a circulating compressor into the bottom evaporator to vaporize a bottom liquid of the high-pressure column to generate a rising gas; Liquefied nitrogen liquefied in the generating step is decompressed and introduced into the top condenser to liquefy the top gas of the low-pressure column to generate a reflux liquid, and vaporize in the step of generating a reflux liquid in the low-pressure column Returning the compressed nitrogen gas to the circulating compressor and compressing it;
5. The method for recovering and purifying argon according to claim 4, further comprising a nitrogen circulating step of supplying and circulating the compressed nitrogen gas again to the step of generating the ascending gas. 6. The liquefied nitrogen in the nitrogen circulation step,
6. The method for recovering and purifying argon according to claim 5, wherein the liquefied nitrogen introduced from outside is added to perform the cold supply. 7. The method for recovering and purifying argon according to claim 5, wherein a cold supply is performed at a low temperature obtained by expanding a part of the compressed nitrogen gas in the nitrogen circulation step. 8. The method for recovering and purifying argon according to claim 5, wherein a nitrogen gas in said nitrogen circulation step is used as a regeneration gas in a regeneration step of said adsorption column in said adsorption removal step. 9. A semiconductor manufacturing apparatus such as a single crystal manufacturing furnace containing argon as a main component and containing solids such as dust, oil, water, carbon monoxide, carbon dioxide, oxygen, hydrogen, nitrogen, hydrocarbons and the like as impurities. An apparatus for recovering and purifying argon in exhaust gas from a plant, comprising: dust collecting means for removing solids such as dust, compression means for compressing the exhaust gas to a required pressure, and oil removing means for removing the oil component And a catalytic reaction means for adding hydrogen to the exhaust gas and reacting with oxygen in the exhaust gas to convert it to water, and a plurality of adsorption columns were used to alternately switch an adsorption step and a regeneration step to convert the water by the catalytic reaction means. Adsorption removal means for continuously adsorbing and removing the water and carbon dioxide contained in the water and the exhaust gas, and a main heat exchanger for cooling the exhaust gas by exchanging heat with a low-temperature return liquid obtained by liquefaction rectification, Cooled in the main heat exchanger Liquefaction of low-temperature exhaust gas containing impurities and remaining impurities is liquefied and rectified to separate a high-boiling component concentrate containing high-boiling components having a higher boiling point than argon and a crude argon gas containing low-boiling components having a lower boiling point than argon. A high-pressure column, a low-pressure column for liquefying the crude argon gas separated in the high-pressure column and separating it into high-purity argon and a waste gas in which low-boiling components having a lower boiling point than argon are concentrated, a top gas of the high-pressure column and A double rectification column including a main condenser that exchanges heat with the bottom liquid of the low pressure column and generates a reflux liquid of the high pressure column and an ascending gas of the low pressure column is separated from the double rectification column by the low pressure column. A product recovery path for recovering high-purity argon through the main heat exchanger. 10. The catalyst reaction means includes a heater, a catalyst cylinder, an exhaust gas path, and an added hydrogen path, and a temperature detector provided in the exhaust gas path connecting the heater and the catalyst cylinder. 10. A catalytic reaction temperature control means comprising a heating capacity controller for controlling a heating capacity of the heater by a signal from the temperature detector.
The apparatus for purifying and recovering argon described above. 11. A path for extracting waste gas separated at the top of the low pressure column of the double rectification column through the main heat exchanger,
The argon recovery and purification apparatus according to claim 9, further comprising a path for supplying waste gas extracted from the path as a regeneration gas for the adsorption column in the adsorption and removal means. 12. A path for extracting the high-boiling component concentrate separated at the bottom of the high-pressure column of the double rectification column, means for evaporating the high-boiling component concentrate extracted from the path and raising the temperature; 10. The argon recovery and purification apparatus according to claim 9, further comprising a path for supplying the high-boiling component vaporized gas derived from the means as a regeneration gas for the adsorption column in the adsorption and removal means. 13. The argon recovery and purification apparatus according to claim 12, wherein the means for vaporizing the high-boiling-point component concentrate and raising the temperature is the main heat exchanger. 14. A circulating compressor for compressing a circulating nitrogen gas, and a bottom evaporator for producing a rising gas by vaporizing a bottom liquid of the high-pressure column using the compressed nitrogen gas compressed by the circulating compressor as a heating source. Vessel, a pressure reducing valve for reducing the liquefied nitrogen liquefied in the bottom evaporator, and a top condenser for condensing the top gas of the low pressure column with the liquefied nitrogen decompressed by the pressure reducing valve as a cold source to produce a reflux liquid. 10. The argon recovery and purification apparatus according to claim 9, further comprising a nitrogen circulation path having a condenser and a path for circulating the nitrogen gas vaporized in the top condenser to the suction side of the circulation compressor. 15. The argon recovery / purification apparatus according to claim 14, wherein a cold supply path for introducing liquefied nitrogen for cooling from the outside is connected to the liquefied nitrogen path in the nitrogen circulation path. 16. The argon recovery / purification apparatus according to claim 14, wherein a path is provided for supplying the nitrogen gas in the nitrogen circulation path as a regeneration gas for the adsorption column in the adsorption and removal means. 17. An expansion turbine for introducing a compressed nitrogen gas on the discharge side of a circulating compressor in the nitrogen circulation path and adiabatically expanding to generate cold, and recovering the cold generated by the expansion turbine, and then recovering the nitrogen circulation path. 15. The argon recovery / purification apparatus according to claim 14, wherein the apparatus has a cold generation path comprising a path returning to the suction side of the circulating compressor.