JP3105382B2 - Ultra low dew point air generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement of a dehumidifier, and more particularly to an arrangement for generating dry air having an extremely low dew point as employed in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In recent years, as a semiconductor device such as a DRAM of 16 M or more has been highly integrated, it has been required to execute a semiconductor manufacturing process in a sealed environment. Conventionally, a dry gas such as nitrogen or argon is used for such a sealed environment. However, these dry gases have problems in terms of safety and running cost, and methods of using dry air instead are being studied.

[0003] However, in the conventional dehumidification using a regenerative dehumidifier, whether it is a fixed bed type or a rotary type, the relationship between the ultimate drying degree of the used moisture absorbent and the operation of the ultra-low dew point temperature is caused. Since there are restrictions on the apparatus in the regeneration system, problems such as residual moisture occur, and the ultimate dew point temperature is -70 ° C.
~ -75 ° C was the limit.

[0004] That is, when the dehumidifying operation and the regeneration operation are performed alternately or continuously in the ultra-low dew-point temperature operation using the current apparatus, the high-humidity air generated in the regeneration system is adsorbed on the wall surface. It is mechanically inevitable that moisture is mixed into the dehumidifying system and raises the final outlet moisture. As a result, the conventional regenerative dehumidifier can only supply dry air having a dew point temperature of -70 ° C to -75 ° C, far below the standards required in a semiconductor manufacturing process.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional arrangement of a dehumidifier. An object of the present invention is to provide a new and improved ultra-low dew point air generator capable of generating an ultra-low dew point temperature dry air having a dew point temperature of -90 ° C or less, which is excellent in cost.

[0006]

According to the present invention, there is provided a regenerative dehumidifier having one or more stages for dehumidifying intake air to an intermediate attainable dew point temperature. A non-regenerative dehumidifier installed in series downstream of the dehumidifier to dehumidify the air dehumidified to an intermediate attainable dew point to a final attainable dew point. Is provided.

In the above apparatus, the intermediate dew point temperature is preferably set to -70 ° C to -75 ° C, and the final dew point temperature is preferably set to -90 ° C or lower. Furthermore, it is preferable to use a zeolite having a low ultimate drying degree as a desiccant used in the non-regenerative dehumidifier.

[0008]

According to the present invention, the air taken into the device is
With a regenerative dehumidifier having a high dehumidifying capacity, it is possible to dehumidify to an intermediate ultimate dew point temperature of, for example, -70 ° C to -75 ° C. At this time, by making this regenerative dehumidifier into a multi-stage configuration, dehumidification can be performed more efficiently and stepwise in a short time. Then, for example, from -70 ° C to-
Air that has been dehumidified to an intermediate dew point temperature of 75 ° C. can be dehumidified by a non-regenerative dehumidifier to a final dew point temperature of −90 ° C. or less, for example. In this case, since most of the moisture has been previously dehumidified by the regenerative dehumidifier as the pretreatment device, a small amount of dehumidifier may be used in the non-regenerative dehumidifier as the post-treatment device, and furthermore, the regeneration treatment is performed. Becomes unnecessary. As a result, it becomes possible to generate ultra-low dew-point air with a dehumidifier with reduced equipment costs and reduced operating costs.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an ultra-low dew point air generator constructed according to the present invention will be described below in detail with reference to the accompanying drawings.

As shown, the apparatus of the present invention comprises a two-stage dehumidifier 1 as a pretreatment device and a fixed-bed dehumidifier 2 as a post-treatment device. In the illustrated example, the pretreatment device 1 has a two-stage configuration including a first rotary dry dehumidifier 3 (DA1) and a second rotary dry dehumidifier 4 (DA2), but the present invention is not limited to this. . A single-stage configuration or a multi-stage configuration of three or more stages is also possible depending on the required ultimate dew point temperature and processing speed.

The outside air (OA = required air amount + regeneration exhaust air amount) sucked by the first dehumidification blower 5 (MF1) is equal to the first air.
After being filtered by the outside air inlet filter 6 (f1)
External air processing air conditioner 8 (OA) through airtight damper 7 (V1)
C). The outside air is dehumidified by the outside air processing air conditioner 8 and the temperature is controlled by the first precooler 9 (PC1). Dehumidified up to.

Next, the air dehumidified to the first intermediate dew point temperature is sent to the next stage by the second dehumidifying blower 10 (MF2). In the second stage, similarly to the first stage, the temperature is controlled by the second precooler 11 (PC2), and in the second rotary dry dehumidifier 4, the second intermediate dew point temperature, for example, -75. C. and is sent to the fixed-bed dehumidifier 12 (DA3), which is the final dehumidifier.

On the other hand, the moisture adsorbed by the dehumidification in the first rotary dry dehumidifier 3 is supplied to the first regenerative blower 13 (RF
According to 1), it is taken in through the second outside air inlet filter 13 (f2) and removed by the regeneration air heated by the first regeneration heater 15 (HC1). As a result,
The dehumidifying means (not shown) of the first rotary dry dehumidifier 3 is continuously regenerated and has a constant dew point temperature, for example, -5.
It is possible to maintain 4 ° C.

Similarly, the water adsorbed in the dehumidification by the second rotary dry dehumidifier 4 is supplied to the second regenerative blower 16.
It is taken into the regeneration system by (RF2) and removed by the regeneration air heated by the second regeneration heater 17 (HC2). As a result, the dehumidifying means (not shown) of the second rotary dry dehumidifier 4 is also continuously regenerated, and it is possible to maintain a constant blower dew point temperature, for example, -75 ° C.

However, as described above, in the rotary dry dehumidifier, which is the pretreatment device 1 as described above, high-humidity air in the regeneration system adheres to the dehumidification means by wall surface adsorption, and the air enters the dehumidification system. The final dew point temperature is limited to −70 ° C. to −75 ° C. because it is unavoidable to increase the final outlet moisture due to the structure. Therefore, in the apparatus of the present invention, a non-regenerative dehumidifier is disposed in series as the post-processing apparatus 2 downstream of the pre-processing apparatus 1 so that the limit of the ultimate dew point temperature of the dry air can be reduced.
It is possible to lower the temperature to 90 ° C.

That is, the air having a blast dew point of -75 ° C., which has exited the two-stage dehumidifier as the pretreatment device 1, is supplied to the aftercooler 1
8 (AC), and sent to a fixed bed dehumidifier 12 as a final dehumidifier via a damper 19 (V3), where it is dehumidified to a final dew point temperature of -90 ° C or less. (V5) and final filter 21
It is supplied to a desired temperature control space via (ff).

Here, in order to obtain a final attained dew point temperature of -90 ° C. or less, a moisture absorbent having a low attainable drying degree, for example, zeolite or the like can be used in the fixed-bed dehumidifier 12. However, the moisture absorbent used in the apparatus of the present invention is not limited to zeolite, and various moisture absorbents can be used according to a desired final dew point temperature.

A fixed-bed dehumidifier 1 as a post-processing device 2
As the shape of No. 2, since the used moisture absorbent such as zeolite is in the form of pellets, it is preferable to adopt a structure that improves the moisture absorption efficiency by adjusting the air flow rate and the contact time.

In the apparatus of the present invention, the two-stage dehumidifier, which is the pretreatment apparatus 1, is dehumidified to an intermediate dew point temperature of, for example, about -75 ° C. ° C or lower, the fixed-bed dehumidifier 12 as the post-processing device 2
And the amount of dehumidifying moisture due to a desiccant such as zeolite can be significantly reduced as compared with the dehumidifying moisture amount in a general region.

Therefore, the amount of the used moisture absorbent corresponding to the amount of water to be dehumidified in the post-processing device 2 can be reduced, and the breakthrough time of the moisture absorbent can be prolonged. According to the apparatus of the present invention, even when the amount of the hygroscopic agent in the post-processing device 2 is the same as the amount of the hygroscopic agent in the pre-processing device 1, for example, the hygroscopic agent in the post-processing device 2 can be used for about one year, for example. It is. Further, for the above reason, the desiccant in the post-processing device 2 does not need to be regenerated, and it is possible to greatly reduce equipment costs and operation costs.

For reference, comparing the running cost of the clean dry air using the conventional nitrogen gas and the running cost of the clean dry air according to the apparatus of the present invention, the clean dry air is 1.5 (yen / m 3). Thus, the clean dry nitrogen gas was 16 (yen / m 3), which indicates that the clean dry air according to the apparatus of the present invention is significantly superior in running cost. Moreover, clean dry air is superior in safety and handling compared to clean dry gas, and can be applied in various fields such as a semiconductor manufacturing process.

When operating the apparatus of the present invention, it is necessary to pay attention to several points since the entire apparatus is operated at a low dew point. For example, when the operation is stopped, it is preferable to block the outside air to prevent dew condensation. Furthermore, at the time of startup, it is necessary to adjust the timing of sending air having an intermediate dew point to the fixed-bed dehumidifier 12 as the post-processing device 2 to reduce the load on the dehumidifier of the post-processing device 2.

In the above description, the apparatus of the present invention has been described with reference to a two-stage rotary dry dehumidifier and a fixed bed dehumidifier using zeolite as a desiccant. Not limited. The device of the present invention can be applied to the arrangement of various dehumidifiers within the scope of the technical idea described in the claims.

[0024]

As described above, according to the apparatus of the present invention, for example, -9, which was impossible with the conventional regenerative dehumidifier, was used.
Ultra low dew point air of 0 ° C. or less can be efficiently formed. At this time, according to the apparatus of the present invention, the intake air is once cooled to -70 ° C.
Since dehumidification is performed up to an intermediate dew point temperature of 75 ° C., dehumidification is performed to a desired ultra-low dew point temperature, for example, −90 ° C. or less, using a non-regenerative dehumidifier equipped with a small amount of a dehumidifier as a post-treatment device. Can be. As a result, it is possible to form a dry gas having a super dew point temperature which is superior in safety and running cost as compared with a conventional dry gas.

[Brief description of the drawings]

FIG. 1 is a system diagram of an ultra-low-dew-point air generator configured according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pre-processing apparatus 2 Post-processing apparatus 3 1st rotary dry dehumidifier 4 2nd rotary dry dehumidifier 5 1st dehumidification blower 6 Outside air inlet filter 8 External conditioner 9 1st preheater 10 2nd dehumidification Blower 11 Second preheater 12 Fixed-bed dehumidifier 13 First regenerative fan 14 Outside air inlet filter 15 First regenerative heater 16 Second regenerative fan 17 Second regenerative heater 18 Afterheater 21 Final filter

Claims (3)

(57) [Claims] 1. A regenerative dehumidifier having one or more stages for dehumidifying intake air to an intermediate attainable dew point temperature, and installed in series downstream of the regenerative dehumidifier and dehumidified to an intermediate attainable dew point temperature. A non-regenerative dehumidifier for dehumidifying compressed air to a final attained dew point temperature. 2. The method according to claim 1, wherein said intermediate dew point temperature is from -70.degree.
The ultra low dew point air generator according to claim 1, wherein the temperature is 75C and the final attained dew point temperature is -90C or less. 3. The ultra-low dew point air generator according to claim 1, wherein said non-regenerative dehumidifier contains zeolite as a desiccant.