JPS62299641A - Air circulation method for clean room - Google Patents

Abstract

PURPOSE:To make equipment cost and running cost relatively low and realize a highly reliable clean room in compromising the merits of turburent and laminar flow methods by installing a HEPA filter at one side of a ceiling in a room and a suction hole at one side of a floor facing the filter. CONSTITUTION:In a clean room, one side 25 of a ceiling and one side of a floor facing the side 25 are arranged in a straight line shape and along the side 25 of the ceiling, an 1/4 cylindrical HEPA filter 21 and along one side of the floor, a lattice-shaped suction hole 23 are installed respectively. Air current flows in parallel when viewed from a horizontal cross section and when viewed from a vertical cross section, air discharged from the upper end of the filter 21 flows along the wall located at the opposite side from the ceiling of the clean room 20 and air discharged from the lower part flows along the wall and then along the floor and air discharged from nearly the center of a filter flows across the clean room in a straight line to enter the suction hole 23 and be returned to a duct 24 and therefore, rough and fine stratified air circulation are formed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention <Industrial Applicability> The present invention is particularly applicable to clean rooms such as industrial clean rooms (ICR) and biological clean rooms (BCR), i.e. Related to airflow methods for supplying and discharging clean air to clean rooms.

<Conventional technology> As a clean room airflow system using conventional technology, there are 1
Several methods are known as follows.

(a) Turbulent flow method As shown in Figure 1, clean air is blown out through high-performance filters 10 (HEPA filters) placed at regular intervals on the ceiling surface 11 to dilute the dust generated indoors. ,
Cleanliness is maintained by suction through the suction port at the bottom of the wall.

Since the airflow does not have a certain directionality, dust is spread throughout the room, and high cleanliness cannot be expected, and the cleanliness class (number of particles per cubic foot) is about 10oO to 100,000.

This method has a simple structure and low equipment costs;
Advantages include low airflow, low running costs, and relatively easy expansion of the room. However, the drawback is that the airflow is turbulent, causing dust to circulate within the room, and it takes a long time for it to reach a steady state.

(b) Vertical laminar flow system As shown in Fig. 2, the HEPA filter 11 is arranged on the entire ceiling surface, and clean air is blown out from the grid-like or perforated floor plate 13 arranged on the entire floor surface. It is a suction method. Clean air uniformly flows vertically from the ceiling to the floor and is discharged to wash away dust generated in the room, resulting in high cleanliness (cleanliness class 10 to 100).

This method has no dust accumulation and is highly reliable.
It has advantages such as being less affected by the number of people in the room or the working conditions, and achieving a steady state immediately after the start of operation. However, the problem is that M! The In cost is very high, and since the air volume is large, the running cost is high,
It will also be difficult to expand the room.

(c) Horizontal laminar flow system As shown in Figure 3, this is a system in which a HEPA filter 15 is disposed on the entire wall surface to blow out clean air, and the air is sucked in through the perforated plate wall 14 that forms the entire wall surface on the opposite side. . The clean air flows horizontally through the room, discharging the dust generated inside the room. Cleanliness class is 100-100
It is about 0.

This system has the advantages of no dust accumulation, highly reliable operation, and a steady state immediately after the start of operation. However, the disadvantages are that equipment costs are high, running costs are high due to the large air volume, and the effects of upstream effects are reflected downstream, so care must be taken in the layout and management of personnel and equipment. These include the fact that it is difficult to expand the room.

In addition to the above, there is a local purification method, which is a combination of a turbulent flow method and a laminar flow method.The laminar flow method is used only in areas that require particularly high cleanliness, and the turbulent flow method is used in other parts. That is.

In this way, conventional airflow methods include (a) turbulent flow method,
There are laminar flow methods (B) and (C), and a compromise method (D).High cleanliness can be obtained by controlling the airflow condition to a constant level as in the methods (B) and (C). The structure becomes complicated,
The filter area and air volume become large, and equipment costs and running costs become expensive. vice versa.

According to method (a), which dilutes the room with clean air without controlling the airflow conditions.

The structure is simplified, the filter area and air volume are small, and both the MW cost and running cost are reduced. However, it is difficult to achieve high cleanliness, and high reliability cannot be achieved due to the accumulation of dust.

Therefore, there has been a desire for a new clean room airflow system to replace these conventional systems.

<Problems to be Solved by the Invention> An object of the present invention is to solve the problem by combining the conventional laminar flow method and turbulent flow method, which is different from the method (d) above. The purpose is to try to eliminate the shortcomings of

<Means for Solving the Problems> According to the present invention, from an air conditioning unit disposed in a duct outside a room in which at least one side of the ceiling and one side of the floor facing the ceiling are linear, Clean air is blown out radially at a constant velocity through a filter placed along one side of the ceiling of the room, and is sucked in through a suction port placed along one side of the floor on the opposite side of the room. , a clean room airflow system is provided, characterized in that the airflow is circulated through the duct.

According to this counterflow method, the filter area and air volume are similar to the turbulent flow method, which controls the air flow by reducing the filter area and air volume, and the highly reliable constant air flow is similar to the N flow method. Equipment costs because properties can be obtained.

Both running costs are low and a highly reliable clean room is realized. In addition, the cleanliness class is 100~
It can accommodate a wide range of up to 100,000, and the room can be expanded relatively easily.

<Example> Next, a preferred example of the present invention will be described in more detail based on the drawings.

FIG. 4 illustrates a clean room 2o according to a preferred embodiment of the present invention. A duct 24 is provided outside the clean room 2o, and an air conditioning unit 22 is connected to the duct 24. In the clean room 20, at least one side 25 of the ceiling and one side 26 of the floor facing it are straight, and one side 25 of the ceiling side is straight.
A 1/4 cylindrical HEPA filter 21 is disposed along one side 26 of the floor surface, and a grid-shaped suction port 23, for example, is disposed along one side 26 of the floor surface. The HEPA filter 21 is generally planar, but according to the present invention, it is bent into a 1/4 cylindrical shape and is attached along one side 25 on the ceiling side. By using the HEPA filter 21, dust-free operation can be achieved with a smaller filter area and smaller air volume. FIG. 5 is a perspective view schematically showing only the clean room 2o, in which the filter 21 and the suction port 23 are shown, and the resulting air flow is shown by arrows. As described above, according to the counterflow airflow method of the present invention, the air flow is parallel flow when viewed in a horizontal section, and when viewed in a vertical section, the air blown from the upper end of the filter 21 is The air flows almost along the ceiling of the clean room 20, then flows along the opposite wall, and the air blown out from the lower end of the filter 21 flows along the wall where the filter 21 of the clean room 20 is installed, and then onto the floor. The air flowing along the filter 21 and blown out from approximately the center of the filter 21 straightly crosses the clean room 2o and returns from the suction port 23 to the duct 24, creating a dense and coarse laminar air flow. Therefore, when viewed in a vertical cross section, the airflow flows diagonally as a whole, but as described above, it flows in a state close to laminar flow. Therefore, the above turbulent flow method (a)
This is a compromise between the laminar flow method (b) and the laminar flow method (c).

The present invention is applicable to both industrial and biological cleanrooms, but as with the horizontal laminar flow system, care must be taken to manage personnel and equipment since upstream effects are reflected downstream. There is a need.

Note that since the clean room 20, air conditioning unit 22, and duct 24 form one closed system, clean air is naturally circulated by an unillustrated processor of the air conditioning unit 22, and this circulation is aided. Therefore, a suction fan may be provided at the suction port 23.

<Effects of the Invention> As explained above, according to the present invention, the HEPA filter 21 is disposed on one side of the ceiling side of the room, and the suction port 23 is disposed on one side of the floor surface facing it, The air flow
The advantages of turbulent flow and laminar flow are balanced by parallel flow when viewed in a horizontal section, and diagonal or nearly laminar flow when viewed in a vertical section, thereby reducing equipment costs and A highly reliable clean room can be realized with relatively low running costs.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view showing a conventional turbulent flow clean room, Fig. 2 is a schematic side view showing a conventional vertical turbulent flow clean room, and Fig. 3 is a conventional horizontal turbulent flow clean room. FIG. 4 is a schematic side view showing an air flow type clean room according to the present invention, and FIG. 5 is a perspective view showing only the clean room with the air conditioning unit and duct removed. Explanation of symbols 20...Clean room, 21...HEPA filter,
22...Air conditioning unit, 23...Suction port, 24...
·duct. Figure 4 Figure 5 20... Clean room 21 = HEPA filter 22... Air! 1! Sum unit 23... Suction port 24... Duct Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An air conditioning unit installed in a duct outside a room where at least one side of the ceiling and one side of the floor facing the room are straight lines, and installed along the one side of the ceiling of the room. A clean room characterized in that clean air is blown out radially at a constant velocity through a filter, sucked in through a suction port arranged along the one side of the floor on the opposite side of the room, and circulated through the duct. Airflow method.