JP2002303438A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which can remove impurities from clean air and possesses a temperature regulating function and a humidity regulating function together. SOLUTION: This air conditioner is provided with a heat exchanger 7 which has a coil 7c wherein a heat medium flows and which performs heat exchange between clean air and a heat medium, and a pure water dropper 40 which catches particles or gas-form impurities contained in the clean air by supplying pure water to the surface of the coil 7c thereby forming a water film of flowing- down pure water on the surface of the coil 7c, in a clean air circulation path which is supplied with outside air with its humidity and the temperature regulated from an outside conditioning unit which is equipped with a temperature control means for regulating the outside air to a specified temperature and a humidity control means for regulating the outside air into a specified humidity range, and this supplies the coil 7c with the heat medium which raises the surface temperature of the coil 7c more than the dew point of the clean air before passing the heat exchanger 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner capable of simultaneously controlling temperature, humidity and removing impurities from clean air in a circulation system.

[0002]

2. Description of the Related Art In recent years, in the manufacturing process of a semiconductor memory after entering a mass production system of 64M DRAM, trace particles and gas (NH ₃ , Cl
₂ , SO ₂ , HF, etc.) have been found to have a very large effect on production. These impurities may be contained in the outside air, or may be generated in a semiconductor manufacturing process in a clean room.

At present, as a countermeasure, an impurity removing device for removing the impurities from the outside air before being introduced into a clean room (hereinafter referred to as an outside air impurity removing device) or a clean room installed in a clean room. Research and development of an impurity removing device for removing the impurities from the air circulating (hereinafter referred to as a circulating air-based impurity removing device) and the like have been conducted.

A so-called air washer type device for removing impurities in an outside air system by spraying water into the introduced outside air to bring it into gas-liquid contact and capturing particles and gaseous impurities contained in the outside air by the sprayed water ( For example, JP-A-6-19391
No. 1) is frequently used.

[0005] This air washer type impurity remover is not suitable for a circulating air type impurity remover because the humidity of the process air increases. This is because it is necessary to control the temperature of the air circulating in the clean room to 23 ± 0.5 ° C. and the relative humidity to about 45 ± 5%.

On the other hand, a chemical filter as disclosed in JP-A-6-198123 is provided with an adsorbing member such as ion-exchange fiber or activated carbon, and the adsorbing member chemically removes particles or gaseous impurities in the air. The chemical filter is removed by adsorption or physical adsorption. Since this chemical filter does not involve an increase in the humidity of the processing air, it is suitable for a circulating air system impurity removal device.

[0007]

However, the chemical filter, which is suitable for a circulating air system, has a limited removal capacity, so the adsorbing member must be periodically regenerated or replaced, and the maintenance is troublesome. Met.
In addition, there is a disadvantage that the running cost is increased because the suction member is very expensive.

Further, the chemical filter has a high initial cost, which has contributed to a rise in construction cost of a semiconductor manufacturing clean room.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and can remove impurities from the circulating system clean air, has both a temperature control function and a humidity control function, and has a simple structure. Another object of the present invention is to provide an inexpensive air conditioner that can be easily maintained.

[0010]

SUMMARY OF THE INVENTION An air conditioner according to the present invention comprises an external air conditioner having a temperature control means for adjusting the outside air to a predetermined temperature and a humidity control means for adjusting the outside air to a predetermined humidity range. A heat exchanger that exchanges heat between the clean air and the heat medium through the jacket in the circulation path of the clean air to which the supplied outside air is supplied; In an air conditioner that supplies a heat medium for increasing the surface temperature of the heat exchanger to a temperature higher than the dew point of the clean air before passing through the exchanger to the jacket, pure water is supplied to the surface of the jacket of the heat exchanger to supply jacket water. The apparatus is characterized in that it has a pure water dropping device for forming a downward flowing pure water film on the surface to capture particles and gaseous impurities contained in the clean air. The air conditioner of the present invention is preferably used when circulating clean air in a clean room used for semiconductor production. In this case, the above-described circulation system includes a clean room as a component thereof.

In this air conditioner, the pure water film formed on the jacket surface of the heat exchanger and the heat exchanger control the temperature and humidity of the clean air, and the pure water on the jacket surface. The water film captures particles and gaseous impurities contained in the clean air and removes them from the clean air.

[0012] The jacket of the heat exchanger may be constituted by a straight tubular coil having a circular cross section. Furthermore,
The jacket may be provided with a fin, and a water film may be formed on the fin.

However, the configuration of the jacket is not limited to this, and if a water film of pure water can be formed on the surface of the jacket and a downward flow of the water film can be formed,
It may have any shape and may be installed in any posture. Further, it is preferable that the water film is formed on the entire surface of the jacket, but the present invention also holds when a water film is formed only on a part of the jacket.

As the heat medium of the heat exchanger, water can be used, or another fluid can be used. As for the method of supplying pure water from the pure water dropping device to the jacket of the heat exchanger, it is preferable to drop the pure water from above the jacket. By doing so, pure water can be supplied only to the surface of the jacket, and the increase in the humidity of the clean air can be suppressed as much as possible.

In the air conditioner of the present invention, it is preferable that the temperature of the heat medium flowing through the jacket is adjusted based on the dew point of the clean air after passing through the heat exchanger.
Further, the humidification effect of the water film formed on the surface of the jacket by the pure water dropping device is offset by the dehumidification effect generated on the jacket surface by the supply of the heat medium to adjust the humidity of the clean air passing through the heat exchanger. As such, it is preferable to supply a heat medium to the jacket. These methods are preferable in that the temperature control and the humidity control for the clean air are efficiently performed in a well-balanced manner.

In the present invention, as a specific structure capable of controlling the heat medium as described above, the heat exchanger, the pure water dropping device, and the heat exchanger provided downstream of the heat exchanger in the circulation path are provided. Humidity detecting means for detecting the humidity of the clean air, and humidification by a water film formed on the jacket surface of the heat exchanger by controlling the temperature of the heat medium supplied to the heat exchanger based on the detected value of the humidity detecting means. Heat medium temperature control means for canceling the action, temperature detection means provided downstream of the heat exchanger in the circulation system for detecting the temperature of clean air, and a heat exchanger based on the detected value of the temperature detection means And a heat medium supply amount control means for controlling the supply amount of the heat medium to be supplied to the device to keep the temperature of the clean air constant. The humidity detecting means can be constituted by a dew point sensor, for example.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an air conditioner according to the present invention will be described below with reference to FIGS.

[First Embodiment] First, a first embodiment of the air conditioner of the present invention will be described with reference to FIGS.

FIG. 1 is a vertical sectional view of a semiconductor manufacturing building. Clean air is supplied to a clean room 1 from an upper return plenum chamber 5 through a fan filter unit 2. Clean air is supplied from the clean room 1 to a lower return plenum chamber 3. , Through the return shaft 4 and again through the upper return plenum chamber 5 and the fan filter unit 2 to the clean room 1. That is, the clean room 1, the lower return plenum chamber 3, the return shaft 4, and the upper return plenum chamber 5 constitute a clean air circulation path.

Further, outside air is introduced into the lower return plenum chamber 3 through the external conditioner 6. The external conditioner 6 includes a filter that removes particles and gaseous impurities from the outside air, a temperature control unit that adjusts air to a predetermined temperature range, and a humidity control unit that adjusts air to a predetermined humidity range. (Not shown) for replenishing the lower return plenum chamber 3 with clean air whose temperature and humidity have been adjusted and impurities have been removed.

A heat exchanger 7 is provided between the lower return plenum chamber 3 and the return shaft 4.
All the clean air flowing from the lower return plenum chamber 3 to the return shaft 4 is supplied to the heat exchanger 7.
Pass through.

As shown in FIGS. 3 to 5, this heat exchanger 7 connects a water inlet header 7a and a water outlet header 7b with a plurality of coils (jackets) 7c, and a large number of flat plates are provided between the coils 7c. The fin 7d is constructed. The coil 7c is meandering as viewed in plan as shown in FIG.

In the heat exchanger 7, water as a heat medium (hereinafter referred to as heat exchange water) flows from the water inlet header 7a to the water outlet header 7b through the coil 7c,
The clean air flowing around c and the heat exchange water flowing inside the coil 7c exchange heat via the coil 7c and the fin 7d.

The structure of the heat exchanger 7 is a dew-condensing type heat exchanger which has been conventionally used exclusively for removing sensible heat in a clean room (the surface temperature of the coil is made higher than the dew point in the (A heat exchanger used so as not to generate condensed water on the surface).

In this heat exchanger 7, heat exchange water is supplied to the coil 7
The heat exchange water supply device 10 for supplying the inside of c is connected. The heat exchange water supply device 10 includes a heat exchange water circulation pump 11 for pumping the heat exchange water to the heat exchanger 7, and a part of the heat exchange water pumped from the heat exchange water circulation pump 11 passes through the heat exchanger 7. It is configured to return to the heat exchange water circulation pump 11 through the heat exchange water circulation pump 11 while bypassing the heat exchanger 7.

More specifically, a part of the heat exchange water pumped from the heat exchange water circulation pump 11 to the flow path 21 flows through the coil 7c from the water inlet header 7a of the heat exchanger 7, and flows from the water outlet header 7b. Through the passage 22, the first control valve 12, the passage 2
3. Return to the suction side of the heat exchange water circulation pump 11 through the normally open manual valve 13 and the flow path 24.

The remaining heat exchange water pumped from the heat exchange water circulation pump 11 to the flow path 21 passes through a bypass flow path 25 branched from the flow path 21, and flows through a first control valve 12 through a flow path 23.
Flows through the heat exchanger 7, merges with the heat exchange water flowing through the heat exchanger 7, and returns to the suction side of the heat exchange water circulation pump 11 through the manually opened valve 13 and the flow path 24 which are always open.

The first control valve 12 is constituted by a three-way valve having three ports.
The second inlet port is connected to the bypass flow passage 25, and the outlet port is connected to the flow passage 23. The first inlet port and the second inlet port are adjusted by adjusting the position of a valve (not shown). It is a control valve that adjusts the inflow ratio of the heat exchange water flowing from the inlet port.

A flow path 26 connecting the heat exchange water circulation pump 11 and the manual valve 13 is connected to a flow path 26 through which the temperature is controlled to a constant temperature (about 5 to 8 ° C.). The supplied makeup water can be supplied to the flow path 24.

A flow path 27 connecting the first control valve 12 and the manual valve 13 is connected to a flow path 27 through which excess heat generated by replenishment from the flow path 26 is supplied. The exchange water can be made to flow out of the flow path 23.

A second control valve 14 is provided in the middle of the flow path 27, and the second control valve 14 adjusts the flow rate of the heat exchange water flowing through the flow path 27 by adjusting the opening thereof. Is a control valve for adjusting the flow rate of makeup water supplied to the flow path 24 from the flow path 26.

The first control valve 12 and the second control valve 14 are
It is configured to be automatically controlled based on a detection value of a temperature sensor (temperature detecting means) 30 or a dew point sensor (humidity detecting means) 32 installed in the return shaft 4 downstream of the heat exchanger 10.

More specifically, the temperature sensor 30 is connected to the heat exchanger 7.
The temperature of the clean air processed in the step is detected, the detection signal is transmitted to the temperature indicating controller 31, and the temperature indicating controller 31 determines the position of the valve body of the first control valve 12 based on the detection signal. , The valve position of the first control valve 12 is adjusted.

Further, the dew point sensor 32 detects the dew point of the clean air processed by the heat exchanger 7, and this detection signal is transmitted to the dew point indicating controller 33, and the dew point indicating controller 33 detects the dew point based on the detection signal. The opening of the second control valve 14 is determined, and the opening of the second control valve 14 is adjusted.

Pure water is dropped on the coil 7c of the heat exchanger 7 by a pure water dropping device (pure water supply device) 40. The pure water dropping device 40 pumps a dropping tank 41 installed above the heat exchanger 7, a water collecting tank 42 installed below the heat exchanger 7, and pure water in the water collecting tank 42 to the dropping tank 41. The pump includes a pure water pump 43 for raising the water and a filter 44 for removing dust and the like from the pure water.

As shown in FIG. 2, many holes 45 are provided at the bottom of the drip tank 41. Regarding the size, number, and perforation position of the holes 45, pure water in the drip tank 41 can be dripped on the top surface of the uppermost coil 7c through each hole 45,
In addition, it is set so that a downward flowing water film can be formed on almost all outer surfaces of all the coils 7c.

In the pure water dropping device 40, the dropping tank 4
The pure water stored in 1 is dropped from the hole 45 to the uppermost coil 7c of the heat exchanger 7, and descends as an outer surface of the uppermost coil 7c as a water film, and immediately from the uppermost coil 7c. Drops are dropped on the top surface of the lower coil 7c, similarly flow down the outer surface of the lower coil 7c sequentially, finally fall into the water collecting tank 42, are pumped up by the pure water pump 43, and are It returns to the drip tank 41 through the filter 44.

The pure water dropping device 40 supplies pure water of high purity to the water collecting tank 42 from a pure water production plant (not shown) in order to keep the purity of the pure water in the water collecting tank 42 constant. , A flow path 49 for supplying pure water in the water collecting tank 42 to the pure water production plant as raw water, and a return pump 46.

In this embodiment, the temperature indicating controller 31 and the first control valve 12 constitute a heating medium supply amount controlling means, and the dew point indicating controller 33 and the second controlling valve 14 constitute the heating medium temperature controlling means. Is composed.

Next, the operation of the air conditioner will be described. As mentioned above, clean air is in clean room 1
The lower return plenum chamber 3 → the return shaft 4 → the upper return plenum chamber 5 → the clean room 1 are circulated in this order.

Now, it is assumed that particles or gaseous impurities are generated in the semiconductor memory manufacturing process in the clean room 1 and the impurities diffuse into the clean room 1 and flow together with clean air.

The clean air passes through the heat exchanger 7 in the middle of the circulation path. At this time, heat exchange between the clean air and the heat exchange water flowing inside the coil 7c is performed via the coil 7c and the fin 7d, and the temperature of the clean air is adjusted to a set temperature.

Since a water film of pure water is formed on the outer surface of the coil 7c of the heat exchanger 7, the clean air that has come into contact with the water film is slightly humidified. Further, due to the gas-liquid contact between the pure water film and the clean air, particles and gaseous impurities contained in the clean air are captured or dissolved in the water film, flow down the coil 7c together with the water film, and fall into the water collecting tank 42. To fall. As a result, particles and gaseous impurities are removed from the clean air.

The pure water containing the impurities is stored in the water collecting tank 42, and a part of the pure water in the water collecting tank 42 is supplied to the pure water producing plant by the flow path 49 and the pure water return pump 46. And the water is processed at the same time. At the same time, pure water of high purity is supplied to the water collecting tank 42 from the flow path 48,
The purity of the pure water in 2 is kept within a predetermined purity range.

In this air conditioner, the heat exchanger 7
The temperature of the heat exchange water flowing through the coil 7c of the heat exchanger 7
And the flow rate of the heat exchange water flowing through the coil 7c of the heat exchange water 7 based on the temperature of the clean air after passing through the heat exchanger 7. This controls the exchange capacity of the heat exchanger 7, the surface temperature of the coil 7c, and the temperature of the pure water film formed on the surface of the coil 7c.

That is, the humidifying effect on the clean air due to the formation of the pure water film on the surface of the coil 7c is controlled so as to be offset by changing the temperature of the heat exchange water flowing in the coil 7c. This is microscopically, a dehumidifying action occurs on the surface of the coil 7c, and this dehumidified component is transferred to the coil 7c.
This is compensated for by vaporization from pure water flowing on the surface of c.

The specific control method in this embodiment is as follows. When the rise of the dew point of the clean air is detected by the dew point sensor 32, the second control valve 14 is operated to increase the opening degree, and the heat exchange water supply device 1 is operated.
The temperature of the heat exchange water is lowered by increasing the amount of the heat exchange water supplied to zero, and the surface temperature of the coil 7c is lowered below the dew point to enhance the dehumidifying effect.

Conversely, when the dew point sensor 32 detects a decrease in the dew point of the clean air, the dew point sensor 32 operates to reduce the opening of the second control valve 14 to supply the heat exchange water supply device 10. When the amount of heat exchange water is reduced,
As a result, the temperature of the heat exchange water rises due to various heat sources installed in the clean room, the surface temperature of the coil 7c rises above the dew point, and the humidifying action becomes stronger.

Further, based on the temperature of the clean air detected by the temperature sensor 30, the valve position of the first control valve 12 is automatically controlled, and the flow rate of the heat exchange water flowing through the coil 7c is changed. Keep the temperature constant.

In this way, the temperature adjustment and the humidity adjustment of the clean air are balanced, so that the temperature and humidity in the clean room can be kept constant. In addition, excessive humidification in summer can be prevented.

[Second Embodiment] In the first embodiment described above, a pure water film is formed only on the surface of the coil 7c of the heat exchanger 7, but the second embodiment is not limited to this. Then, a water film of pure water is also formed on the fins 7d of the heat exchanger 7.

For this purpose, a hole 45 is provided in the dropping tank 41 of the pure water dropping device 40 so that pure water can be dropped also on the upper end of each fin 7d. In this case, the surface area of the pure water film can be increased, and the efficiency of removing impurities from clean air can be increased.

[Third Embodiment] Next, an air conditioner according to a third embodiment of the present invention will be described with reference to FIG. The difference between the air conditioner of the third embodiment and the air conditioner of the first embodiment is that (1) there are three heat exchangers, and (2) three heat exchangers 7A and 7B. , 7C only for the configuration of the heat exchange water supply device 10 for supplying the heat exchange water,
Other configurations are the same as those of the first embodiment.

As shown in FIG. 6, in the heat exchange water supply device 10 in the air conditioner of the third embodiment, the heat exchange water pumped from the heat exchange water circulation pump 18 to the flow path 21 is supplied to each heat exchanger. The heat exchange water circulation pump 18 is supplied to the water inlet headers (not shown) of the heat exchangers 7A, 7B and 7C and passes from the water outlet headers (not shown) of the heat exchangers 7A, 7B and 7C through the flow paths 22 and 24. The flow path 24 can be supplied with heat exchange water through the flow path 26, and the heat exchange water can be supplied from the flow path 22 through the flow path 27 to the flow path 22.
Can be drained from. In FIG. 6, reference numeral 19 denotes an on-off valve.

The flow path 27 is provided with a second control valve 14 for controlling the amount of pure water supplied in the same manner as in the first embodiment. The drive motor (not shown) of the heat exchange water circulating pump 18 is equipped with an inverter that varies the number of rotations of the motor.
Control is performed via the temperature indicating controller 31 based on the detected value of 0, and the flow rate of heat exchange water is automatically controlled. That is, the third
In this embodiment, the temperature indicating controller 31 and the heat exchange water circulating pump 18 constitute a heat medium supply amount control unit.

The operation of the air conditioner of the third embodiment is the same as that of the first embodiment, and the description is omitted.

[0057]

As described above, according to the air conditioner of the present invention, the heat exchanger is installed in the clean air circulation path, and the pure water is dropped on the jacket surface of the heat exchanger by the pure water dropping device. A water film is formed to capture particles and gaseous impurities contained in the clean air, and the outside air adjusted to a predetermined temperature and humidity is introduced into the circulation system by an external air conditioner to be replenished. The remarkable effect that temperature control, humidity control, and impurity removal can be performed simultaneously with respect to clean air is produced.

Further, the air conditioner of the present invention has such a function, has a simple structure, is easy to maintain, and is low in cost.

In the air conditioner of the present invention, the temperature of the heat medium flowing through the jacket is adjusted based on the dew point of the clean air after passing through the heat exchanger.
There is an excellent effect that the temperature and humidity of the clean air can be adjusted efficiently and in a well-balanced manner with a very simple structure.

In the air conditioner of the present invention, the humidification effect of the water film formed on the jacket surface by the pure water dropping device is offset by the dehumidification effect generated on the jacket surface by the supply of the heat medium, and the heat exchange is performed. By supplying a heat medium to the jacket to adjust the humidity of the clean air passing through the vessel, the temperature and humidity of the clean air can be adjusted in a balanced and efficient manner with an extremely simple structure. It works.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the pure water dropping device in the first embodiment of the air conditioner of the present invention.

FIG. 3 is a front view of the heat exchanger in the first embodiment of the air conditioner of the present invention.

FIG. 4 is a right side view of the heat exchanger in the first embodiment of the air conditioner of the present invention.

FIG. 5 is a plan view of a heat exchanger in the first embodiment of the air conditioner of the present invention.

FIG. 6 is a schematic configuration diagram of a heat exchange water supply device according to a third embodiment of the air conditioner of the present invention.

[Explanation of symbols]

Reference Signs List 1 clean room (clean air circulation path) 3 lower return plenum chamber (clean air circulation path) 4 return shaft (clean air circulation path) 5 upper return plenum chamber (clean air circulation path) 7 heat exchanger 7c coil ( Jacket) 12 first control valve (heat medium supply amount control means) 14 second control valve (heat medium temperature control means) 18 heat exchange water circulation pump (heat medium supply amount control means) 30 temperature sensor (temperature detection means) 31 temperature Indicating controller (heat medium supply amount control means) 32 Dew point sensor (humidity detecting means) 33 Dew point indicating controller (heat medium temperature control means) 40 Pure water dropping device (pure water supply device)

Claims (3)

[Claims] 1. A clean air circulation path to which temperature- and humidity-controlled outside air is supplied from an outside air conditioner having temperature control means for adjusting outside air to a predetermined temperature and humidity control means for adjusting outside air to a predetermined humidity range. A heat exchanger that exchanges heat between the clean air and the heat medium through the jacket, and a dew point of the clean air before passing through the heat exchanger. In an air conditioner that supplies a heat medium that raises the surface temperature of the jacket to the jacket, a pure water is supplied to the surface of the jacket of the heat exchanger, and a water film of downward flowing pure water is formed on the surface of the jacket. An air conditioner comprising a pure water dropping device formed to capture particles and gaseous impurities contained in clean air. 2. The air conditioner according to claim 1, wherein the temperature of the heat medium flowing through the jacket is adjusted based on the dew point of the clean air after passing through the heat exchanger. 3. A clean air passing through a heat exchanger, wherein a humidifying effect of a water film formed on a surface of the jacket by the pure water dropping device is offset by a dehumidifying effect generated on a jacket surface by a supply of a heat medium. The air conditioner according to claim 1 or 2, wherein the heat medium is supplied to the jacket so as to adjust the humidity of the air conditioner.