• Suzhou DAAO

Selection of clean room air conditioning purification solutions

Purification scheme
1. Whole room purification
The centralized purification air conditioning system is used to create a purification treatment mode with the same cleanliness environment in the whole room, which is called full room purification. This is the first way to develop clean technology, and it is still used. This method is suitable for places with large and numerous process equipment and the same indoor cleanliness. However, this method has large investment, complex operation and management, and long construction cycle.

2. Local purification
The purification treatment method of purifying air conditioners or local purification equipment (such as clean workbench, shed type vertical laminar flow unit, laminar flow hood, etc.) to create a certain cleanliness level environment in local areas in the general air-conditioning environment is called local purification. This method is suitable for the places where the production batch is small or the original plant is used for technical transformation. At present, the most widely used purification treatment method is the combination of full room purification and local purification, which is a purification method generated in the development of clean technology. It can not only ensure a certain degree of indoor cleanliness, but also achieve a high cleanliness environment in local areas, so as to achieve the dual purpose of meeting the requirements of production for a high cleanliness environment and saving energy. For example, in an operation section that requires 100 grade cleanliness, when the production batch is small, as long as local purification equipment such as a clean bench or laminar flow hood is used in the turbulent clean room with low cleanliness, the purification method of combining full room purification with local purification can be realized.

3. Clean tunnel
The purification treatment method of tunnel shaped clean environment composed of two laminar flow process areas and turbulent flow operation activity areas in the middle is called clean tunnel. This is a typical combination of full room purification and local purification. It is a widely used purification method, also known as the third generation purification method.

According to the different equipment constituting the clean tunnel, the clean tunnel can be divided into the following forms.
Bench clean tunnel
This form of clean tunnel is to connect the clean worktables with each other and cancel the middle side wall to form a tunnel type production line required for production. When the process requires vertical laminar flow, the vertical laminar flow workbench can be selected. When the process requires horizontal laminar flow, the horizontal laminar flow workbench shall be selected. This kind of purification method is easier to ensure the high cleanliness of local space than the whole room purification, and because the worktables are connected with each other, it can reduce or prevent cross pollution. In addition, the requirements for the building are relatively simple, as long as the environment with turbulent clean room is required. The disadvantage is that the size of the clean workbench is fixed, which makes the operating surface lack sufficient flexibility. The process equipment must adapt to the size of the workbench, and it is not convenient to adjust.

Shed type clean tunnel
This type of clean tunnel is composed of a clean shed, that is, a shed type vertical laminar flow unit connected in series in a production line. According to the process requirements, the area of the clean shed can be changed. The air can be all indoor circulating, or connected to the centralized purification air conditioning system to absorb some fresh air. Shed type clean tunnel is suitable for places with large process equipment.

Cover type clean tunnel
This type of clean tunnel is composed of a laminar flow hood, that is, a hood type vertical laminar flow unit connected in series in a production line. Because the depth of laminar flow hood is smaller than that of clean shed, it is only applicable to places with small process equipment. The air circulation mode is the same as that of shed type clean tunnel and bench type clean tunnel. It is a kind of clean tunnel that is widely used at present.

Centralized air supply clean tunnel
The clean tunnel in this form is composed of a static pressure box full of high-efficiency filters in the centralized air supply system. The width of the laminar flow working area can be determined according to the requirements of the process. Unlike the bench type, shed type and cover type clean tunnels, the width of the laminar flow working area is limited due to the size of local purification equipment, and the design can be more flexible. When this form is adopted, the return air can pass through the technical clamp, or the trench can be set in the turbulent flow operation activity area as shown in the figure. In addition, the industrial pipeline can be arranged at the side along the wall panel of the work area, and the exhaust pipe is connected to the trench.

Selection of clean room air conditioning purification solutions1
Selection of clean room air conditioning purification solutions2

The characteristics of clean tunnel are as follows:
1. Different cleanliness degrees are created in the tunnel, thus making full use of the characteristics of different clean air flows to meet the process requirements to the greatest extent. Generally, the two sides of the tunnel are laminar flow working areas with high cleanliness, and the middle is turbulent flow operation activity area. The process area is connected into a line, which is easy to use, and the activities of personnel will not cause cross pollution.

2. As the laminar flow area is reduced in the tunnel, the capital construction cost and operation cost are saved by more than one third compared with the vertical laminar flow clean room with full room purification. The clear height of turbulent flow operation area is much higher than that of laminar flow process area, which can meet the requirements of personnel comfort.

3. The technical duct can be used as the return air duct, and various industrial pipelines can be arranged and process auxiliary equipment can be installed. The maintenance of local purification equipment (clean workbench, clean shed, laminar flow hood, etc.), industrial pipelines and process auxiliary equipment constituting the clean tunnel can be carried out in the technical gallery. Since the technical clamp is negative pressure relative to the clean tunnel, the maintenance work will not cause pollution to the clean tunnel, and the maintenance work can be carried out without stopping the process production.

The local purification equipment, ceiling, wall panel, air return outlet, doors and windows and other components required for cleaning the tunnel can be standardized and modular, processed and produced by professional factories and assembled on site. At the same time, the clean tunnel can be quickly disassembled and reassembled, providing convenience for process change.

4. The clean tunnel can be equipped with a purification air conditioning system according to a certain scale, so the air conditioning system can be generalized and serialized, which can greatly shorten the design cycle.

5. In general, the requirements of clean tunnel for buildings are relatively simple. As long as the environment of turbulent clean room is available, the requirements can be met.

4. Clean piping
The purification treatment method of placing the process production line requiring ultra-high cleanliness level (such as level 1 or 10) in the pipeline isolated from the indoor air environment is called clean pipeline. This method requires that the process production must be automated, and the high efficiency filter must be 0.1 μ M dust particles as the standard to achieve ultra-high cleanliness. In addition, because the air in the pipeline is purified by this method, the air supply and return volume is very small, which can greatly save energy. It is the development direction of clean technology, also known as the fourth generation purification method.

The purification treatment scheme described above shall be determined according to specific conditions.

At present, the three purification treatment methods that have been relatively mature technically are full room purification, local purification (including the combination of full room purification and local purification) and clean tunnel. In the engineering design, one or two purification methods should be selected as the design scheme in combination with the specific conditions.

Under the condition that the process requirements are met, the local purification method shall be selected as far as possible. Local purification adopts local purification equipment, which is realized in general air-conditioning environment. Since the local purification equipment is generally produced by professional factories with high quality and can speed up the site construction, this scheme can be given priority in the reconstruction project.

When only local purification can not meet the process requirements, the combination of local purification and full room purification can be used as the design scheme.

When the above purification methods can not meet the process requirements, the whole room purification method is selected as the design scheme. Because this method will make the whole room have the same cleanliness, especially when the cleanliness level is high, the initial investment and operation cost are very high. Therefore, the area of the clean room should be strictly controlled.

Selection of clean room air conditioning purification solutions3
Selection of clean room air conditioning purification solutions4

Post time: Apr-29-2021