JP3227367B2 - Impurity removal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a clean room,
To prevent contamination in clean enclosed spaces such as clean booths and clean benches, that is, to remove impurities in air to obtain gas clean air that removes pollutants including gas such as solid fine particles and volatile organic substances. It concerns the device.

[0002]

2. Description of the Related Art In recent years, in the field of electronics and biochemicals, particularly in the field of semiconductor manufacturing, advanced technologies affected by minute amounts of pollutants have been greatly developed. Since these advanced technologies must be performed in a closed space with extremely clean air, methods for purifying air, maintaining cleanliness in closed spaces, improving the performance of air filters, Formation is a major issue. This type of clean closed space is usually provided with a circulating purification path to introduce a part of the gas inside to remove contaminants and return to the original closed space to maintain cleanliness. When it becomes necessary to increase the cleanliness of the closed space, the number of times of circulating purification of the gas in the closed space is increased, or the collection rate of particles having a particle diameter of 0.3 μm is 99.7% or more. High performance filters, eg HEPA
(High Efficiency Particul
ate Air) filters have been developed and the collection performance against particulates and bacteria has been greatly improved.

[0003]

However, the HEP
Conventional pollutant removal method of using high-performance filter such as A filter is mainly because focus on separation of the solid particles in the gas have been placed, NO _X, SO _X and chemical gases, such as volatile organics It was not very effective in removing contaminants. However, for example, in a clean room or a clean bench used in the electronics industry, a chemical solution of an acid or an alkali is often used, and contaminant gas is easily generated from an acidic substance or an alkaline substance. In this case, even if a high-performance filter is inserted into the circulation purification path in order to maintain the cleanliness of the clean enclosed space, there is almost no effect of removing gaseous pollutants.
Cannot maintain cleanliness. In addition, when there is a cleaning device that handles hydrofluoric acid, etc., hydrofluoric acid and the like leaking from the cleaning tank are contained in the air circulating in the clean room, and attack the glass fiber, which is a filter material constituting a high-performance filter, and remove the glass fiber. Ions and elements which cannot be present, such as boron B and aluminum Al, which are included, have been detected. For such contamination, a large amount of new clean gas is taken in from outside,
The air had to be exchanged for air in a clean enclosed space.

Recently, there has been proposed an activated carbon filter in which a neutralizing reactant is carried on activated carbon in order to separate a chemical contaminant such as a mist containing an acid or an alkali salt, an acidic gas or the like from an atmospheric gas. However, as a result of the reaction, the activated carbon filter
Neutralized salts and the like generated on the activated carbon surface may be desorbed and scattered in the gas, which may contaminate the clean space,
There was a problem that it could not be easily adopted as it was.

As shown in FIG. 5, which is a block diagram of a conventional impurity removing apparatus, Japanese Patent Application Laid-Open No. 6-198123 discloses a method in which cation and anion exchange fibers and an alkali are added to solve this problem. A filter 33 combining activated carbon fibers has been proposed. In this filter 33, gas pollutants such as acidic gas and organic gas are mainly activated carbon layers, and acidic substances, alkaline substances,
Alternatively, the neutral salt or the like generated in the activated carbon layer is mainly removed in the ion exchange fiber layer, so that there is no re-emission into the air. However, the exchange capacity of the ion-exchange fiber is limited. When the exchange capacity is full, the removal capacity is lost, and there is a problem that it is necessary to stop the apparatus and replace the ion-exchange fiber.

In FIG. 5, 30 is a clean room, 31 is a HEPA filter, 32 is a dust filter,
34 is a suction blower, 35 is a prefilter, 36 is a heat exchanger, 37 is a humidifier, 38 is a circulation blower, 39 is a prefilter, and 40 is a circulation purification path.

It is an object of the present invention to provide an impurity removing apparatus capable of removing gaseous contaminants in a gas without stopping the apparatus and replacing the impurity removing means.

[0008]

According to a first aspect of the present invention, there is provided an apparatus for removing impurities according to the present invention.
An impurity removal device for removing impurities in air, provided with a high-performance filter having a collection rate of 9.7% or more, comprises a pipe through which the air is introduced, which is made of a material through which gas passes but liquid does not pass. A first unit through which the air passes, the circulation unit circulating pure water so as to contact the surface of the pipe; It is characterized by being introduced into a performance filter.

Further, the impurity removing apparatus according to the present invention comprises one or a plurality of pipes through which air that has passed through the high-performance filter, which is made of a material that allows gas to pass but does not allow liquid to pass, 2. The impurity removing apparatus according to claim 1, further comprising a second unit through which the air passes, the second unit having means for circulating pure water so as to contact the pipe surface.

Further, according to a third aspect of the present invention, in the impurity removing apparatus of the present invention, the circulating means may be configured such that, in a region where the pure water contacts the pipe, the pure water flows in a direction opposite to a direction in which the air flows through the pipe. 3. The impurity removing device according to claim 1, wherein the impurity is circulated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments of the present invention.

FIG. 1 is a diagram showing a configuration of a clean room having an impurity removing apparatus according to one embodiment of the present invention.
2 is a diagram showing a cross section taken along the line AA in FIG. 1, FIG. 3 is a diagram for explaining the principle of the present invention, and FIG. 4 is a diagram showing a configuration of an experimental apparatus for evaluating the present invention. is there. FIG.
4 to 1, 1 is a HEPA filter, 2a, 2b
Is a first and second unit bundled with a porous polytetrafluoroethylene tube 15 around which is filled with pure water 14,
3 is a hygroscopic material made of silica gel or the like, 4 is a pure water circulation pump, 5 is a pipe, 6 is a filter, 7 is a supply line of pure water 14 circulating in the two units 2a and 2b, and 8 is two A waste liquid line for pure water 14 circulating in units 2a and 2b, 9 is a clean room, 10 is a floor having an exhaust hole, 11a, 11b, 11c are air circulation paths, 12 is a suction blower, 13 is an air supply port, 14 Represents pure water, 15 represents a porous polytetrafluoroethylene tube, 16 represents particulate impurities, and 17 represents gaseous impurities.

According to the present invention, a porous polytetrafluoroethylene tube may be used as long as it is made of a material that is porous and does not allow passage of a liquid having a large surface tension, but is made of a material having a property of allowing gas to easily pass therethrough. However, the present invention is not limited to this. Further, the porous polytetrafluoroethylene tube 15 used in the present embodiment has an outer diameter of 5 mm,
The inner diameter was 4 mm, the porosity was 70%, and the length was 50 cm.

Further, as shown in FIG. 3, the present invention relates to a porous polytetrafluoroethylene tube 15.
A gas having particulate impurities 16 and gaseous impurities 17 is passed through a tube made of a material through which gas passes but liquid does not pass through the hole 15a, and pure water 14 is circulated around the tube. 17 is absorbed in pure water 14. The mechanism of collecting impurities is determined by the diffusion coefficient of the impurities. The gaseous impurities 17 having a large diffusion coefficient are absorbed by the pure water 14 against the flow of air in the porous polytetrafluoroethylene tube 15. The particulate impurities 16 having a small particle diameter cannot pass through the porous polytetrafluoroethylene tube 15 and are not collected by the pure water 14.

Further, as shown in FIG. 2, the present invention is applied to a stage subsequent to the first unit 2a in which a porous tube whose periphery is filled with pure water 14 is bundled, or the first unit 2a and pure water 14
A high-performance filter for removing particulate impurities is provided between the second unit 2b and the porous unit bundled with the porous tube. The high performance filter of the present invention is not limited to the HEPA filter 1,
Any filter having a collection rate of 99.7% or more for 0.3 μm particles can be applied.

Further, the structure of the clean room 9 using the impurity removing apparatus of the present invention shown in FIG.
a, high-performance filter 1, second unit 2b, and hygroscopic material 3
Are connected in series, air is introduced into the clean room 9 via these, and the air is discharged from the exhaust holes of the floor provided in the clean room 9 to the air circulation paths 11a, 11b, 11c. Then, this air is sent to the first unit 2a again using the suction blower 12. At this time, the pure water 14 around the porous polytetrafluoroethylene tube 15 in the first unit 2a and the second unit 2b is circulated using the pure water circulation pump 4 in a direction opposite to the direction in which the air is sent. But pure water 14 in the same direction as the air flow.
May be circulated. However, it is more pure water 14
It is desirable because the contact efficiency between the gas and the gaseous impurities 17 is improved.

Further, a filter 6 is mounted in the middle of the pipe 5 for supplying the pure water 14 flowing through the first unit 2a and the second unit 2b, and unnecessary foreign substances contained in the pure water 14 flowing through the pipe 5 are removed. Further, since the pure water 14 is replaced at regular intervals, clean pure water 14 is supplied from the supply line 7, and the pure water 14 containing gaseous impurities 17 in the air is discharged from the waste liquid line 8.

Hereinafter, the step of removing impurities in the air using the impurity removing apparatus of the present invention will be described with reference to FIGS.

First, the air from the air supply port 13 is supplied to the first unit 2a by the suction blower 12. This air is
It passes through the porous polytetrafluoroethylene tube 15 in the second unit 2a and reaches the second unit 2b via the HEPA filter 1. When air passes through this porous polytetrafluoroethylene tube 15, only gaseous impurities 17 contained in the air are absorbed by pure water 14,
Removed from air. Then, when passing through the HEPA filter 1, the particulate impurities 16 contained in the air are removed from the air.

Next, the air that has reached the second unit 2b is
Further, the gaseous impurities 17 contained in the air are removed and sent to the clean room 9 via the hygroscopic material 3 made of silica gel or the like connected to the second stage of the second unit 2b. The moisture absorbent 3 prevents the moisture content of the clean air from increasing.

Next, the air in the clean room 9 is supplied to the floor 1.
0 through an exhaust hole provided in the air circulation path 11a,
It is sent to the first unit 2a by the suction blower 12 again.

In this embodiment, the apparatus for removing impurities according to the present invention comprises a first unit 2a, a high-performance filter (HEPA).
Although the first and second units 2b are sequentially connected, the first unit 2a and the high-performance filter 1 may be connected. However, the configuration in which the first unit 2a, the high-performance filter 1 and the second unit 2b are sequentially connected in that the gaseous contaminants generated from the salt of the particulate impurities attached to the high-performance filter 1 can be removed. Is desirable.

Referring to FIG. 4, the result of evaluating the gas contaminant removing ability of the impurity removing apparatus using the present invention using a standard gas generator will be described. In FIG. 4, reference numeral 20 denotes a diaphlom pump, 21 denotes a silica gel filling tank, 22 denotes a molecular sieve tank, 23 denotes an activated carbon filling tank, 24 denotes a NaCO ₃ impregnated filter and H ₃ PO ₄ impregnated filter, 25 denotes a standard gas generator, 26 Denotes a mixing chamber, 27a denotes a first diffusion scrubber, 27b denotes a second diffusion scrubber, and 28 denotes a flow meter.

A permeation tube or a diffusion tube is attached to the standard gas generator 25,
At a constant temperature of 35 ° C., a standard gas was generated. The reagent stock solution of the standard gas for the diffusion tube is H
NO ₃ is 61% and HCl is 35%.

The standard gas generated from the standard gas generator 25 is diluted by passing through a silica gel filling tank 21, a molecular sieve tank 22, an activated carbon filling tank 23, an NaCO ₃ impregnated filter and an H ₃ PO ₄ impregnated filter 24. The clean air obtained from was used. The air suction flow rate was 11 cm ³ / min.

Also, the first and second serially connected two
After a standard gas was sucked into the diffusion scrubbers 27a and 27b for a certain period of time, the absorption solution 29a of the first scrubber 27a and the absorption solution 29 of the second diffusion scrubber 27b were each diluted to a certain volume, and analyzed by an ion chromatograph analyzer. Two types with different concentrations of the standard gas (No. 1 and No. 1 in Table 1)
Table 1 shows the analysis results of the removal examined in 2).

[0027]

[Table 1]

The removal efficiency (measured value) and the theoretical value in Table 1 were calculated by the following equations. Removal efficiency (measured value) (%) = [C _D1 / (C _D1 + C _D2 )] × 100 (1) Theoretical value (C / Co) (%) = 0.819 exp (−3.657Z) +0. 09 7exp (-22.3Z) + 0.033exp ( -57Z) ·· (2) in addition, in the formula (1), C _D1 is a gas component concentration that is removed by the first diffusion scrubber, C _D2 and the second This is the concentration of gas components removed by the diffusion scrubber. The theoretical value is obtained from the Gormley-Kennedy equation (Z ≧ 0.0312). In the equation (2), Z is Z = πDL / Q, and D is the diffusion coefficient (cm ^2).
/ Sec), Co is the concentration of the component of interest at the inlet of the tube, C is the concentration of the component of interest at the outlet of the tube, L is the effective length of the tube (cm), and Q is the air suction flow rate (cm ³ / sec). ).

As shown in Table 1, the removal efficiency of the acidic and basic gases was measured using the diffusion scrubbers 27a and 27b. As a result, all the measured gases had a removal rate of 97% or more, which was almost the same as the theoretical value. It can be seen from the agreement that by passing the air through the porous polytetrafluoroethylene tube 15 filled with pure water, the gaseous impurities in the air can be sufficiently removed. Others
98% or more formic acid and 97% acetic acid for organic gases
The above removal efficiency was obtained, and it was found that almost all organic gases could be removed as well as inorganic gases.

[0030]

As described above in detail, by using the present invention, gaseous impurities are removed by circulating pure water, so that the removal can be performed without stopping the apparatus and replacing the impurity removing means. Process time can be reduced. Further, since air is introduced into the high-performance filter after the acidic gaseous impurities are removed, the life of the high-performance filter is extended.

According to the second aspect of the present invention, the high-performance filter removes particulate impurities in the air, and the gaseous contaminants generated from the salt of the particulate impurities attached to the high-performance filter. Can also be removed from the air by collecting it in pure water.

Further, by using the present invention, the trapping efficiency of gaseous impurities can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a clean room having an impurity removing device according to an embodiment of the present invention.

FIG. 2 is a view showing an AA cross section in FIG.

FIG. 3 is a diagram for explaining the principle of the present invention.

FIG. 4 is a diagram showing a configuration of an experimental apparatus for performing the evaluation of the present invention.

FIG. 5 is a configuration diagram of a conventional impurity removing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 HEPA filter 2a, 2b unit 3 Hygroscopic material 4 Pump for pure water circulation 5 Piping 6 Filter 7 Pure water supply line 8 Pure water waste liquid line 9 Clean room 10 Floor part with an exhaust hole 11a, 11b, 11c Air circulation path 12 Suction blower 13 air supply port 14 pure water 15 porous polytetrafluoroethylene tube 15a hole 16 particulate impurities 17 gaseous impurities

Continuation of the front page (56) References JP-A-2-26605 (JP, A) JP-A-6-23218 (JP, A) JP-A-6-198123 (JP, A) JP-B-49-45142 (JP) , B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 46/00 B01D 53 / 18,53 / 22 F24F 7/06

Claims (3)

(57) [Claims] 1. The method according to claim 1, wherein the particle having a particle diameter of 0.3 μm is 99.
An apparatus for removing impurities in air, provided with a high-performance filter having a trapping rate of 7% or more, comprising: A first unit through which the air passes, and a circulating means for circulating pure water so as to contact the surface of the pipe; and the air passing through the first unit is a high-performance filter. An impurity removing device characterized by being introduced into a device. 2. One or more tubes into which air passing through the high-performance filter made of a material that allows gas to pass but does not pass liquid is introduced, and circulates pure water so as to contact the surface of the tubes. The impurity removing apparatus according to claim 1, further comprising a second unit having means, through which the air passes. 3. The method according to claim 1, wherein the circulating means circulates the pure water in a direction opposite to a direction in which the air flows through the pipe in a region where the pure water and the pipe are in contact with each other. The impurity removing device according to claim 2.