JP2003028459A - Corrosion-prevention method for cooling heat-exchanger in air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an effective corrosion-prevention method, economical and useful for a long time by solving the problem that parts made of copper such as pipes, fins, etc., used in a heat exchanger of an air conditioner placed in a clean room are subject to corrosion by gaseous substances such as SOX, NOX, nitric acid, acetic acid, etc., contained in the air, which is supplied into the clean room, and the life of the heat exchanger is shortened. SOLUTION: The air conditioner is provided with the heat exchanger for cooling and dehumidifying air passing therethrough. In a pretreatment, gaseous substances contained in the air are brought into contact with a photocatalyst or filters, etc., under UV-irradiation in order to decompose and remove the substances. Thus, corrosion of copper or a copper alloy, components of the heat exchanger can be prevented.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a predetermined temperature condition,
The present invention relates to a method for preventing corrosion of a constituent material made of copper or a copper alloy in a heat exchanger in an air conditioner that produces air adjusted to a humidity condition, and particularly in a clean room or a clean room with a closed circulation system, heat exchange of a local air conditioner. The present invention relates to an anticorrosion method for container constituent materials.

A clean room intended by the present invention is a clean room used in semiconductors, liquid crystals, precision machinery, medical care, food, pharmaceutical industry, etc., and an air conditioner is provided with a decompression or vacuum processing device and an exposure device. For air conditioning of the whole room, also carrier box, clean box,
It is used for local air conditioning in the step of applying resist ink to a wafer such as a stocker or lithograph, which requires uniform film thickness.

[0003]

2. Description of the Related Art In a conventional clean room, the air filter function has been dealt with only by removing fine particles by a dust filter, and gaseous substances are introduced into the clean room without being substantially removed. Also,
In the clean room, conditions such as gas generated by work in the clean room, degassing from clean room components and equipment used, and high circulation of air to save energy are added. Concentration of the gaseous substance of is higher than that of the outside air.

As the gaseous substance in the clean room,
Examples of neutral substances include organic solvents, examples of acidic substances include SO _X , NO _X , hydrochloric acid, nitric acid, formic acid, acetic acid, and examples of alkaline substances include ammonia and amines.

In a clean room, the air in the room is sucked by an air conditioner, and the room air is adjusted to a constant temperature and humidity condition suitable for the purpose of use of the room and the required accuracy, but is discharged from the air conditioner. Since the air to be contained contains the above-mentioned high-concentration gaseous substance virtually untreated, it is highly likely that the wafer base material and the substrate are contaminated. For this reason, conventionally, silica gel, zeolite, alumina,
Install an adsorbent such as activated carbon or ion exchange fiber,
Measures have been taken to protect the wafer base material or substrate to be worked by these adsorbents.

An air conditioner for cooling and adjusting the air in the clean room is generally constructed so that the air and the refrigerant pass through the inside of the device, as shown in FIG. According to this device, first, the introduced air 1 is once cooled by the evaporator 2. The evaporator 2 forms a part of a refrigeration system 3 using, for example, Freon as a refrigerant, and the vaporized refrigerant 4 at the outlet of the evaporator 2 is compressed by a refrigerator 5 and cooled and condensed by cooling water or air by a condenser 6. It
Next, the refrigerant liquefied by the expansion valve 7 becomes a refrigerant in a wet gas state due to adiabatic free expansion, and enters the evaporator 2.

The air is cooled through a heat exchanger provided in the evaporator 2 and having a member made of copper or copper alloy, while the refrigerant is heated and returns to the refrigerator 5. The air discharged from the evaporator 2 is finely adjusted by the warmer 8 and the humidifier 9 to have a desired temperature and humidity, and is blown to the target by the blower 10.

[0008]

Copper having a high thermal conductivity is used for the heat exchanger portion of the air conditioner, but since this copper is corroded by the gaseous substances contained in the air in the clean room, It is protected by plating with nickel. Another known method is to protect the heat exchanger part made of copper by providing an adsorbent at the air intake of the air conditioner, but this method has a long life.
It is not used much in practice because it is 3 months long, half a year long, and expensive.

In addition to this, aluminum is another material having a good thermal conductivity in place of copper, but in this case as well, there are problems of corrosion due to a condensate in which various chemical substances are dissolved and problems of processing. Not used very often. Further, titanium may be used as a material having a high thermal conductivity in place of copper, but this is not economically feasible at this time.

Among the conventional techniques, in local air conditioning in a clean room, it is necessary to keep the film thickness of the resist ink uniform as the miniaturization of the work progresses in the wafer lithographic process and the resist ink performance. From the viewpoint of maintenance, the accuracy of constant temperature and humidity has become extremely high. For this reason, hydrochloric acid and ammonia have been kept low in the gaseous substances in the clean room. However, SO _X , NO
_{X 2} , nitric acid, formic acid, acetic acid, etc. are still untreated.

As described above, the heat exchanger portion of the air conditioner is made of copper or copper alloy having good thermal conductivity. However, since the air in the clean room contains the gaseous substance, this gaseous state Of the substances, SO _x , NO _x , nitric acid,
Acetic acid or the like is taken into the condensed water when the water is condensed in the heat exchanger portion and corrodes the copper or copper alloy. In addition, amines, organic solvents, etc., are contacted with condensed water and hydrolyzed to form organic acids such as ammonia, formic acid and acetic acid.

Table 1 shows a case in which members such as tubes and fins in the heat exchanger in the evaporator 2 are not plated,
When nickel plating is applied, the temperature is 23 ° C,
Air 1 having a relative humidity of 50% and a flow rate of 1 m ³ / min was introduced into the evaporator 2, and cooling operation was performed at a temperature of 7 ° C. and a relative humidity of 100% at the outlet of the evaporator 2, that is, the inlet of the warmer 8. The comparison of the life of the heat exchanger in the case is shown.

[0013]

[Table 1]

As shown in Table 1, when nickel plating is applied to the members of the heat exchanger, the effect of nickel plating is extremely large. Therefore, there is a concern about the stability of the plating film that the nickel content elutes in a relatively short time, which is considered to be the uneven service life. Therefore, this method may have a drawback that the film thickness must be maintained thick for safety. The analysis of trace components in condensed water was carried out by ion chromatography. _- constituents of C00H is 70 to 90% by weight in acetic acid, the remainder was almost formic acid.

[0015]

[Means for Solving the Problems] As described above, the copper heat exchanger member in the air conditioner is conventionally plated with nickel or the like to prevent corrosion, but its life is short, so that it is 2-3 years. It took about 7 to 8 years at the longest and the cost was high, so there was a problem that it could not be said to be a complete measure. The present invention aims to solve the above-mentioned problems in the anticorrosion measures of conventional air conditioner cooling heat exchangers, and is effective, long life, low cost and economical corrosion of copper members in air conditioners. It is intended to provide preventive measures.

The present invention, as a concrete means therefor, is as follows.
In the air conditioner equipped with a heat exchanger for cooling the air passing therethrough and cooling it to a dew point or lower when dehumidification is required, in preventing corrosion of copper or copper alloy that is a constituent material of the heat exchanger, Gaseous substances contained in the air are pre-irradiated with a photocatalyst or a filter,
Alternatively, it is characterized by preventing the corrosion of copper or copper alloy, which is a constituent material of the heat exchanger, by cleaning the air by bringing it into contact with a combination of a photocatalyst under ultraviolet irradiation and a filter to decompose the air.

As means for contacting and decomposing a gaseous substance contained in the air with a photocatalyst under irradiation of ultraviolet rays, titanium oxide having photocatalytic ability is used to decompose and remove the gaseous substance contained in the air. It is preferable.

As a means for removing the gaseous substances contained in the air to prevent the corrosion of the copper heat exchanger member, a filter having an adsorption ability for acid gas, alkaline gas and organic gas may be used. Good.

Further, as a means for decomposing the gaseous substance contained in the air, the gaseous substance is first brought into contact with a filter having an adsorption ability for acidic gas, alkaline gas and sulfur-based gas in the preceding stage, In the subsequent subsequent step, the gaseous substance contained in the air may be removed by contacting with titanium oxide having a photocatalytic ability under irradiation of ultraviolet rays.

Further, the gaseous substance to be removed is preferably one or more of ammonia, nitric acid, nitrogen oxides, acetic acid, formic acid and amine.

[0021]

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment Next, an embodiment of the present invention will be described. FIG. 1 is a view for explaining flows of air and a refrigerant passing through the inside of an air conditioner, and basically the same as the device shown in FIG. However, in this case, instead of directly introducing air into the evaporator 2, a pretreatment device 20 equipped with a chemical filter or a photocatalyst irradiated with ultraviolet rays is provided on the upstream side of the evaporator 2. The air 21 treated by the pretreatment device 20 is supplied to the evaporator 2.

As in the example of FIG. 2, the introduced air 21 is once cooled by the evaporator 2. The evaporator 2 forms a part of a refrigeration system 3 using, for example, Freon as a refrigerant, and the vaporized refrigerant 4 at the outlet of the evaporator 2 is compressed by a refrigerator 5 and cooled and condensed by cooling water or air by a condenser 6. It Next, the refrigerant liquefied by the expansion valve 7 becomes a refrigerant in a wet gas state due to adiabatic free expansion, and enters the evaporator 2.

The air is cooled through a heat exchanger provided in the evaporator 2 and provided with a member made of copper or a copper alloy, while the refrigerant is heated and returns to the refrigerator 5. The air discharged from the evaporator 2 is finely adjusted by the warmer 8 and the humidifier 9 to have a desired temperature and humidity, and is blown to the target by the blower 10. The position of the blower 10 is not limited to this.

The above-mentioned copper or copper alloy is used for the heat exchange portion of the evaporator 2 for cooling the introduced air 21, but aluminum or aluminum-based metal is used as a material having good thermal conductivity in addition to copper or copper alloy. You may. However, it is necessary to pay attention when using aluminum because aluminum is a problem of corrosion due to a condensate in which various chemical substances are dissolved and there are processing restrictions. The air condition in this case is the same as in Table 1 such that the temperature is 23 ° C,
Air 1 having a relative humidity of 50% and a flow rate of 1 m ³ / min was cooled at the outlet of the evaporator 2, that is, the inlet of the warmer 8 to a temperature of 7 ° C. and a relative humidity of 100%. Further, there is no change in temperature and humidity conditions by the pretreatment device 20.

Table 2 shows the pretreatment on the upstream side of the evaporator 2.
When pre-treated with a chemical filter in device 20
And when pretreated with a photocatalyst under UV irradiation.
The value of the gas concentration in the
It shows the time until the noh stops. This place
The heat exchanger tubes and plates are the same as in Table 1.
I did not apply plating. Trace components in air 1
Monia 100-250ppb, NO_X20-50pp
b, HNO_Three30-50ppb, HCL10-50p
pb, HF10-50 ppb, non-methane hydrocarbon 1-2
ppm (of which ₋COOH is 0.7 to 1.5 ppm,
The amine compound is 0.001 to 0.02 ppm).

[0026]

[Table 2]

The chemical filters used in Table 2 are N-type (corresponding to alkali gas), H-type (corresponding to acidic gas), C-type (corresponding to organic gas) of honeycomb type clean solve 2CH series manufactured by Japan Puretech Co., Ltd. 3 types, each size is 305 mm × 610 mm
× A thickness of 55 mm was used by overlapping. Moreover, the photocatalyst irradiated with ultraviolet rays is MKU manufactured by KEZIPAK CORPORATION.
40, size 305 mm x 610 mm x thickness 88 m
m, the irradiation light has a wavelength of 300 to 400 nm and a peak wavelength of 368 nm. Ventilation volume is about 6 m ³ / mi
n. The analysis of the trace components in the air 21 was based on the ion chromatography method, the gas chromatograph mass spectrometry method and the chemiluminescence method.

[0028]

Example 2 In this case, as in the case of Example 1, not only a chemical filter system and a photocatalyst system under UV irradiation as pretreatment but also a combination thereof, that is,
As shown in Table 3, when only the chemical filter is used,
The pretreatment device 2 is prepared by preparing three examples of a combination of a chemical filter and a photocatalyst under UV irradiation and a case of only a photocatalyst under UV irradiation.
It shows the numerical value of the gas concentration in the air when the air 21 pretreated with 0 is supplied to the evaporator 2 and the time until these pretreatment devices 20 stop functioning. In this case as well, the air condition is the same as that of the first embodiment.

[0029]

[Table 3]

In the case of only the chemical filter system used in Table 3, as a chemical filter, a honeycomb type clean solve 2CH manufactured by Nippon Pure Tech Co., Ltd.
Four types of series, N type (for alkali gas), H type (for acid gas), S type (for sulfur gas), C type (for organic gas), each 305m in size
m × 610 mm × thickness 55 mm were used by overlapping.

When the chemical filter system and the photocatalyst system under the irradiation of ultraviolet rays are used in combination, the chemical filter system is used in the former stage and the photocatalyst system is used in the latter stage. Are three types of N-type (corresponding to alkali gas), H-type (corresponding to acidic gas), and S-type (corresponding to sulfur-based gas) of Honeycomb-type clean solve 2CH series manufactured by Nippon Pure Tech Co., Ltd., each size is 305 mm x 610 mm.
× A 55 mm thick layer is used by overlapping, and as a photocatalyst under the irradiation of ultraviolet rays in the latter stage, MK manufactured by KZY PACK CO., LTD.
U40, size 305mm x 610mm x thickness 88
mm, and the irradiation light used had a wavelength of 300 to 400 nm and a peak wavelength of 368 nm.

Further, as the photocatalyst in the case of only the photocatalyst system under the irradiation of ultraviolet rays, MKU40 manufactured by K.K.
m × 610 mm × thickness 88 mm, and the irradiation light had a wavelength of 300 to 400 nm and a peak wavelength of 368 nm.

In each of the above three examples, the air flow rate is about 6 m ³ / min. The analysis of trace components in the air 21 was based on ion chromatography, gas chromatography mass spectrometry and chemiluminescence.

[0034]

According to the method of the present invention, as shown in Examples 1 and 2, the photocatalyst under UV irradiation, the chemical filter, or the UV light is supplied before the air is supplied to the evaporator 2. Since it is brought into contact with the combination of the photocatalyst and the chemical filter under irradiation, the gaseous substances present in the air can be removed by this, and this purified air passes through the heat exchanger in the next step. It has the effect of significantly improving the corrosion resistance of the copper parts that make up the heat exchanger.

As shown in Table 1 of the conventional example, in the case where copper parts such as tubes and fins in the heat exchanger are nickel-plated, durability of about 8 years is recognized in the long case, but In the case of not applying the above, there is a problem that the refrigerant leaks in a very short period of about 1.5 years, whereas according to the method of the present invention, as shown in Tables 2 and 3, air is removed. As a pretreatment before supplying to the heat exchanger, when the photocatalyst under UV irradiation, or a chemical filter, or a combination of a photocatalyst under UV irradiation and a chemical filter, is contacted, the pretreatment device is continuously operated. Even if the test was continued by operating for 1.5 years, no pitting corrosion was observed in the copper parts in the heat exchanger, which was a good result. Further, it was confirmed that the deterioration of the catalyst was not observed when the photocatalyst was used.

According to Table 1 of the conventional example, when nickel plating is applied to the copper parts of the heat exchanger, durability for a relatively long period of time is recognized. Therefore, as a conventional countermeasure, this nickel plating method is used. Although it has been considered to be optimal, the method of contacting a gaseous substance in the air with a photocatalyst under ultraviolet irradiation or a chemical filter as in the present invention eliminates the need for protection by nickel plating, The effect of can be realized by an inexpensive method, and also has the effect of reducing the pollution caused by the plating work.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the flow of an air conditioner equipped with an air pretreatment device of the present invention.

FIG. 2 is an explanatory diagram showing the flow of a conventional air conditioner.

[Explanation of symbols]

1: Introduced air 2: Evaporator 3: Frozen system 4: Evaporator outlet refrigerant 5: Refrigerator 6: Condenser 7: Expansion valve 8: Heater 9: Humidifier 10: Blower 20: Pretreatment device 21: Air from pretreatment device outlet

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F28F 19/00 511 F24F 1/00 371Z F term (reference) 3L051 BC10 3L053 BD01 BD03 BD05 3L058 BE02 BF09 4G069 AA03 BA04A BA04B BA48A CA01 CA11 CA12 CA13 CA17 CA19 EA18 EB14Y

Claims (5)

[Claims] 1. An air conditioner equipped with a heat exchanger for cooling the air passing therethrough and cooling it to a temperature below the dew point when dehumidification is required. Corrosion of copper or copper alloy, which is a constituent material of the heat exchanger. In order to prevent this, the gaseous substances contained in the air are decomposed by contacting them with a photocatalyst under UV irradiation, or a filter, or a combination of a photocatalyst under UV irradiation and a filter in advance, and using the constituent materials of the heat exchanger. A method for preventing corrosion of an air conditioner cooling heat exchanger, characterized by preventing corrosion of certain copper or copper alloy. 2. The air conditioner cooling heat exchanger according to claim 1, wherein a gas purification method is used which decomposes and removes a gaseous substance contained in air by using titanium oxide having a photocatalytic ability under irradiation of ultraviolet rays. Anticorrosion method. 3. The air conditioner cooling according to claim 1, wherein a gas purification method is used in which a gaseous substance contained in the air is removed by using a filter having an adsorption ability for an acidic gas, an alkaline gas and an organic gas. Anti-corrosion method for heat exchanger. 4. Removal of gaseous substances contained in the air by using a filter having an adsorption ability for an acidic gas, an alkaline gas and a sulfur-based gas in the first stage, and using titanium oxide having a photocatalytic ability in the second stage under UV irradiation. The anticorrosion method for an air conditioner cooling heat exchanger according to claim 1, wherein the gas purification method for performing the above is used. 5. The gaseous substance to be removed is ammonia,
The anticorrosion method for an air conditioner cooling heat exchanger according to claim 1, comprising one or more of nitric acid, nitrogen oxide, acetic acid, formic acid, and amine.