JP5032516B2 - Air pollutant removal device - Google Patents

Description

  The present invention relates to an apparatus for removing air pollutants for dissolving and removing contaminants contained in air by bringing gas to liquid contact with the air to be treated and a circulating absorption liquid. is there.

  In recent years, in the manufacturing environment of semiconductor factories and liquid crystal factories, not only particulate pollutants contained in the air but also molecular pollutants (AMCs: Airborne Molecular Contaminants) have deteriorated product yield, performance, and reliability. Has been reported to affect Therefore, a very clean environment in the clean room is required, and it is necessary to manage AMCs in addition to particulate pollutants.

  As one of the technologies for removing AMCs from the air, a gas-liquid contact type air pollutant removal device (air washer) is known. This removal device (air washer) absorbs air to be treated and absorbs it. It is a device that removes water-soluble components such as ammonia and sulfur dioxide contained in the air by dissolving them in the absorbing liquid by bringing them into gas-liquid contact. It is installed in external controllers of semiconductor factories and liquid crystal factories. ing.

  As a conventional device for removing this type of air pollutant, for example, as shown in FIG. 2, always supply makeup water is supplied directly to the most downstream medium 1, and upstream of the water tank 3 by a circulation pump 2. A continuous water supply type removal device 5 that sequentially supplies water to the medium 4 is known (see, for example, Patent Document 1).

  As another conventional type of removal device, as shown in FIG. 3, the conductivity of the absorbing liquid in the water tank 7 is detected by a conductivity meter 9, and the conductivity detected by the conductivity meter 9 is a predetermined value. A conductivity control type removal device 12 that opens the solenoid valve 10 and supplies makeup water to the water tank 7 when it is out of the range of the control value is known.

  Furthermore, as another type of conventional removal device, as shown in FIG. 4, the pH value of the absorbent in the water tank 14 is detected by a pH meter 16, and the pH value detected by the pH meter 16 is a predetermined control value. When the electromagnetic valve 17 is deviated from the above range, the replenishing water is supplied to the water tank 14 or the pH value of the absorbing liquid in the water tank 20 is detected by a pH meter 22 as shown in FIG. There are known pH control type removal devices 18 and 25 that selectively remove cations or anions by an ion removal device 23 so that the pH value detected by the meter 22 does not fall outside the range of a predetermined control value. (For example, see Patent Documents 2, 3, and 4).

JP 2000-317248 A JP 2004-230385 A JP 2002-239331 A JP 2000-79319 A

  However, in the case of the conventional continuous water supply type removal device 5 described above, there is a problem that the amount of makeup water increases and running cost increases because the makeup water must be constantly supplied.

  In the case of the conventional conductivity control type removal device 12 described above, there is no problem as long as the ratio of the acidic component and the alkaline component in the air is equal. For example, sulfur dioxide in winter when the consumption of fossil fuel increases. The concentration of the solution increases, or the gas discharged from the factory exhaust gas treatment device is mixed into the outside air taken into the room depending on the wind direction, so that the pH of the absorbing solution is biased to either acidic or alkaline and is removed. There existed a problem that the removal performance of the acidic component of the apparatus 12 or an alkaline component will fall.

  Among the conventional pH control type removal devices described above, in the case of the removal device 18 shown in FIG. 4, the makeup water is not supplied unless the pH value of the absorption liquid is out of the control value range. There is a problem that the concentration of the water-soluble component contained therein becomes high, the conductivity continues to rise, the water-soluble component such as ammonia is re-scattered, and the removal performance is lowered. Further, there is a problem that the scale of the eliminator 15 is generated due to the scattering of the absorbing liquid, and the maintenance frequency increases. Furthermore, if buffer solution or acid / alkaline solution is used as make-up water, it becomes a pollution source of air itself, and if general water (for example, clean water, industrial water, etc.) is used, scale is likely to be generated. There was also a problem.

  Furthermore, among the above-described conventional pH control type removal devices, in the case of the removal device 25 shown in FIG. 5, in addition to the problems in the case of the removal device 18 shown in FIG. Since an ion removing device using decomposition is used, maintenance such as replacement of parts becomes indispensable, and there is a problem that maintenance cost becomes high.

  Further, in the above-described conventional conductivity control type removal device 12, when the pH value is 4.9 or less or 6.3 or more, the removal performance of the water-soluble component is remarkably lowered, and depending on the pH value, the removal performance is 30. On the other hand, in the above-described conventional pH control type removal devices 18 and 25, when the conductivity is 30 μS / cm or more, the removal performance of the water-soluble component is remarkably lowered, and depending on the value of conductivity. May have a removal performance of 30% or less. Therefore, in the most advanced semiconductor factories and liquid crystal factories, in order to make AMCs in the clean room extremely low, the load on the chemical filter that may be installed downstream of the air washer in the external air conditioner increases. There was also a problem that the replacement frequency of the chemical filter increased and the running cost increased.

  The present invention has been made to solve the above-described problems, and by simultaneously managing the pH value and conductivity of the absorbing liquid, the removal performance of water-soluble components in the air is constantly maintained at a high level, and depending on the scale. It is an object of the present invention to provide an air pollutant removal device that can reduce the frequency of maintenance of an eliminator and the like and the frequency of replacement of a chemical filter and can greatly reduce the cost.

  In order to achieve the above-described object, the present invention is to dissolve and remove contaminants contained in the air by bringing the air to be treated and the circulating absorbing liquid into gas-liquid contact with each other. A device for removing contaminants in the air, the pH value detecting means for detecting the pH value of the absorbing liquid, the conductivity detecting means for detecting the conductivity of the absorbing liquid, and the pH detected by the pH value detecting means. An absorption liquid replenishing means for replenishing the absorbent with a clean absorption liquid when at least one of the value and the conductivity detected by the conductivity detection means is out of a predetermined control value range. It is characterized by that.

  In the air pollutant removal apparatus according to the present invention, the control value range of the pH value is preferably pH 4.9 to 6.3, and the control value range of the conductivity is preferably 30 μS / cm or less. .

  In the apparatus for removing pollutants in the air, it is preferable that the clean absorption liquid supplied by the absorption liquid supply means is pure water.

  According to the present invention, by simultaneously managing the pH value and conductivity of the absorption liquid, it is possible to always maintain the removal performance of water-soluble components in the air, regardless of the conditions such as seasons and regions, The manufacturing environment required for clean rooms such as semiconductor factories and liquid crystal factories can be created easily and reliably. Moreover, when a chemical filter is installed on the downstream side of the air washer in the external air conditioner, the frequency of replacing the chemical filter can be reduced, and the cost can be greatly reduced.

  Further, since the replenishment amount of the absorbing liquid is replenished only when the pH value or conductivity of the absorbing liquid is out of the predetermined control value range, the replenishing amount of the absorbing liquid can be minimized.

  Furthermore, since the occurrence of scale due to the scattering of the absorbing liquid can be prevented, the maintenance frequency can be reduced.

  Furthermore, when pure water is used as the absorbing liquid to be replenished, since the absorbing liquid does not become a contamination source, the frequency of maintenance can be further reduced.

It is a systematic diagram which shows the removal apparatus of the air pollutant which concerns on embodiment of this invention. It is a systematic diagram which shows the removal apparatus of the conventional regular water supply system. It is a systematic diagram which shows the removal apparatus of the conventional conductivity control system. It is a systematic diagram which shows the removal apparatus of the conventional pH control system. It is a systematic diagram which shows another removal apparatus of the conventional pH control system.

  Hereinafter, an air pollutant removing apparatus according to an embodiment of the present invention will be described with reference to the drawings. Here, FIG. 1 is a system diagram showing an air pollutant removing apparatus according to an embodiment of the present invention.

  The air pollutant removal device 30 according to the present embodiment includes a gas-liquid contact means 40 for bringing the air to be processed and the circulating absorbing liquid into gas-liquid contact with each other, and an absorbing liquid storage for storing the absorbing liquid. Means 50, absorption liquid circulation means 60 for circulating the absorption liquid between the gas-liquid contact means 40 and the absorption liquid storage means 50, pH value detection means 70 for detecting the pH value of the absorption liquid, Conductivity detection means 80 for detecting the conductivity of the absorption liquid, and at least one of the pH value detected by the pH value detection means 70 and the conductivity detected by the conductivity detection means 80 is a predetermined management value. And an absorption liquid replenishing means 90 for replenishing the absorption liquid with a clean absorption liquid when it is out of the range.

  The gas-liquid contact means 40 is provided in a chamber 41 through which air to be processed flows, and a plurality of media 42 are arranged so as to be orthogonal to the air flow direction (arrow direction from left to right in FIG. 1). It is configured by being arranged in parallel (two stages in FIG. 1). Each medium 42 is made of a hydrophilic or water-absorbing material such as polyester or ceramic, and a liquid film is formed on the surface when the absorbing liquid is dropped from above. The gas-liquid contact means 40 is not limited to this configuration as long as it has a configuration in which the air and the absorbing liquid are in efficient gas-liquid contact. For example, the gas-liquid contact means 40 is generally used in a conventional air washer. As described above, various modifications are possible, such as spraying the absorbing liquid from the spray nozzle and collecting the scattered mist of the absorbing liquid with an eliminator.

  The absorption liquid storage means 50 includes a water tank 51 disposed below each medium 42, and the water tank 51 includes a humidification water supply pipe 53 including a ball tap 52, an overflow pipe 54, and a valve 55. The drainage pipe 56 is connected. In this case, it is preferable that pure water is used for the humidifying water supply supplied through the humidifying water supply pipe 53.

  The absorption liquid circulation means 60 is divided from the water tank 51 to the upper part of the medium 42 for the absorption liquid circulation, the circulation pump 62 provided in the middle of the main pipe 61, and the main pipe 61 to be branched from each medium. A branch pipe 63 directed to 42 and a flow meter 64 provided in the middle of each branch pipe 63 are provided.

  The pH value detection means 70 includes a pH meter 71 that is branched and connected in the middle of the main pipe 61 for circulating the absorbing liquid, and the pH meter 71 is electrically connected to an electromagnetic valve 92 described later via a pH indicator 72. Has been. In this case, the control value of the pH value is preferably set in the range of pH 4.9 to 6.3.

  The conductivity detecting means 80 is provided with a conductivity meter 81 that is branched and connected in the middle of the main pipe 61 for circulating the absorbing liquid. The conductivity meter 81 is electrically connected to the electromagnetic valve 92 via the conductivity indicator 82. It is connected. In this case, the conductivity management value is preferably set in a range of 30 μS / cm or less.

  The absorbing liquid replenishing means 90 includes a replenishing water pipe 91 disposed from a water supply source (not shown) to the water tank 51, and an electromagnetic valve 92 and a flow meter 93 are connected to the replenishing water pipe 91. In this case, it is preferable to use pure water as the absorbing liquid to be replenished via the replenishing water pipe 91.

  Next, the operation of the air pollutant removing device 30 having the above-described configuration will be described with reference to the drawings.

  The absorption liquid in the water tank 51 is pumped up by the driving of the circulation pump 62, and the absorption liquid is dropped onto each medium 42 from above through the main pipe 61 and each branch pipe 63, and a liquid film is formed on the surface of each medium 42. The When the air to be processed introduced into the chamber 41 passes through the medium 42 having the liquid film formed on the surface in this way, the air and the absorbing liquid come into gas-liquid contact, and the air is humidified. Water-soluble components such as ammonia and sulfur dioxide contained in the air are dissolved and removed in the absorbing solution. Thereafter, the air purified by removing the water-soluble component is supplied into the clean room, while the absorbing solution in which the water-soluble component is dissolved is dropped into the water tank 51 and returned.

  Thus, while the absorption liquid is circulating, the pH value of the absorption liquid in the main pipe 61 is always detected by the pH meter 71 and the conductivity of the absorption liquid in the main pipe 61 is detected by the conductivity meter 81. Has been detected. When the pH indicator 72 determines that the pH value of the absorbing liquid is out of a predetermined control value range (pH 4.9 to 6.3), or the conductivity of the absorbing liquid is a predetermined value. In any case where the conductivity indicator 82 determines that the control value is out of the range (30 μS / cm or less), the electromagnetic valve 92 is opened, and clean absorption liquid is replenished from the water supply source. The water is supplied into the water tank 51 through the pipe 91. At this time, the amount of absorbed liquid supplied is adjusted by the flow meter 93.

  Further, when the liquid level in the water tank 51 falls below a predetermined level due to humidification, the ball tap 52 is activated and water is supplied into the water tank 51 through the humidifying water supply pipe 53. On the other hand, if the liquid level in the water tank 51 exceeds a predetermined level at this time, the absorbing liquid in the water tank 51 is discharged to the outside through the overflow pipe 54.

  According to the air pollutant removal device 30 according to the above-described embodiment, the removal performance of water-soluble components in the air can always be maintained high regardless of the season or region, and compared with the conventional removal device. Thus, the removal performance can be improved up to twice or more. Thereby, highly clean air can be supplied into the clean room, and a manufacturing environment required for a clean room such as a semiconductor factory or a liquid crystal factory can be created easily and reliably. As a result, product yield, reliability, and performance can be improved. Further, the scale of the eliminator or the like does not occur due to the scattering of the absorbing liquid, and the maintenance frequency can be reduced. Furthermore, chemical filters may be installed on the downstream side of the air washer in the external air conditioner in order to make AMCs extremely low in the clean rooms of the most advanced semiconductor factories and liquid crystal factories. As a result, the load on the chemical filter can be greatly reduced, and the lifetime of the chemical filter can be extended. Further, the concentration on the downstream side of the chemical filter can also be reduced.

  In the air pollutant removal device 30 according to the above-described embodiment, the pH meter 71 and the conductivity meter 81 are branched and connected in the middle of the main pipe 61 for circulating the absorbing liquid. For example, the pH meter 71 and the conductivity meter 81 may be attached anywhere as long as the pH value and the conductivity of the absorbent can be appropriately measured, such as being attached to the outer surface of the water tank 51.

  In addition, the installation position of the end of the makeup water pipe 91 is not limited to the water tank 51 described above, and may be installed, for example, above the most downstream medium 42. Since it is possible to immediately supply a clean absorbent to the medium 42 when it is determined that the pH value or the electrical conductivity is out of the range of the predetermined control value, the control responsiveness can be improved.

  Further, in the above-described embodiment, when the valve 55 of the drain pipe 56 is changed to a solenoid valve, the makeup water is determined when it is determined that the pH value or conductivity of the absorbing liquid is out of the predetermined control value range. It is also possible to automatically open the electromagnetic valve of the drain pipe 56 in correspondence with the electromagnetic valve 92 for use, and forcibly discharge the absorbing liquid in the water tank 51 to the outside.

  Furthermore, in this case, the opening time of the electromagnetic valve of the drain pipe 56 and the electromagnetic valve 92 for make-up water according to the magnitude of the degree to which the pH value or conductivity of the absorbing liquid deviates from the predetermined control value range. It is also possible to configure so that the length of each can be changed.

DESCRIPTION OF SYMBOLS 30 Air pollutant removal apparatus 70 pH value detection means 80 Conductivity detection means 90 Absorption liquid replenishment means

Claims (2)

Removal of air pollutants for dissolving and removing pollutants including ammonia and sulfur dioxide contained in the air by bringing gas to liquid contact with the air to be treated and the circulating absorption liquid. A device,
PH value detection means for detecting the pH value of the absorbing solution;
Conductivity detecting means for detecting the conductivity of the absorbing liquid;
When the pH value detected by the pH value detection means is out of the range of pH 4.9 to 6.3, which is a management value, or the conductivity detected by the conductivity detection means is a management value of 30 μS / cm or less Absorbing liquid replenishing means for replenishing the absorbing liquid with a clean absorbing liquid in any of the cases,
A device for removing pollutants in the air, comprising: Absorbing liquid to be replenished from the absorbing liquid replenishing means according to the pH value of the absorbing liquid detected by the pH value detecting means or the degree of the degree that the conductivity detected by the conductivity detecting means is out of the management value range The apparatus for removing air pollutants according to claim 1, wherein the amount of the air pollutant is changed.

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