1、Whole room purification
The purification treatment method that uses the centralized purification air-conditioning system to create an environment with the same cleanliness in the entire room is called whole-room purification. This was one of the earliest methods of clean technology developed and is still used today. This method is suitable for places where the process equipment is tall and the number is large, and the same cleanliness is required indoors. However, this method requires large investment, complex operation and management, and long construction period.
2、Local purification
Using purification air conditioners or local purification equipment (such as clean benches, shed-type vertical laminar flow units, laminar flow hoods, etc.), the purification treatment method that causes a certain cleanliness level environment in a local area in a general air-conditioned environment is called local purification. This method is suitable for places where the production batch is small or where the original factory building is used for technical transformation. At present, the most widely used purification treatment method is the combination of whole room purification and local purification. It’s produced in development of clean technology. It can not only ensure a certain degree of cleanliness in the room, but also achieve high cleanliness in local areas. So as to achieve the dual purpose of not only meeting the requirements of production for a high-clean environment, but also saving energy.
3、Clean tunnel
The purification treatment method that consists of two laminar flow process areas and a turbulent flow operation area in the middle to form a tunnel-shaped clean environment is called a clean tunnel. This is a typical combination of whole room purification and local purification, and it is a purification method that is currently being promoted, and is also called the third-generation purification method.According to the different equipment that makes up the clean tunnel, the clean tunnel can be divided into the following forms.
(1) table type clean tunnel
This form of clean tunnel is to connect the clean benches to 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 can be selected. This purification method is easier to ensure the high cleanliness of the local space than the whole room purification, and because the workbenches are connected to each other, it can reduce or prevent cross-contamination. In addition, the requirements for the building are relatively simple, only the environment of the turbulent flow cleanroom is required. The disadvantage is that the size of the clean workbench is fixed, so that the operating surface lacks sufficient flexibility. The process equipment must adapt to the size of the workbench, and it is not very convenient to adjust.(2) Shed type clean tunnel
This form of clean tunnel is composed of clean sheds, that is, shed-type vertical laminar flow units connected in series on a production line. According to the process requirements, the area of the clean shed can be changed, and the air can be completely circulated indoors, or it can be connected to a centralized HVAC system to absorb part of the fresh air. The shed-type clean tunnel is suitable for places with large process equipment.(3) Hood type clean tunnel
This form of clean tunnel is composed of a laminar flow hood, that is, a hood vertical laminar flow unit connected in series on a production line. Since the depth of the laminar flow hood is smaller than that of the clean booth, it is only suitable for places with small process equipment. The air circulation method is the same as that of the shed-type clean tunnel and the table-type clean tunnel, and it is a kind of clean tunnel that is currently used more.(4) Centralized air supply type clean tunnel
This form of clean tunnel is composed of a static pressure box full of high-efficiency filters in a centralized air supply system. The width of the laminar flow working area can be determined according to the requirements of the process, unlike the table, shed and hood clean tunnels, which limit the width of the laminar flow working area due to the size of the local purification equipment, and the design can be more flexible. When this form is adopted, the return air can pass through the technical channel, or a trench can be set in the active area of the turbulent flow operation. In addition, industrial pipelines can be arranged on the side of the working area along the wall, and the exhaust pipe is connected to the gutter.Features of Clean Tunnel
(1) Different cleanliness is caused in the tunnel, so that the characteristics of different clean airflows are fully utilized to meet the process requirements to the greatest extent. In general, the two sides of the tunnel are laminar flow working areas with high cleanliness, and the operation activity area in the middle is turbulent flow. The process area is connected into a line, which is convenient to use, and the activities of personnel will not cause cross-contamination.
(2) Due to the reduction of the laminar flow area in the tunnel, the infrastructure cost and operating cost are more than one-third less than that of the vertical laminar flow cleanroom with full room purification. The net height of the turbulent flow operation area is much higher than that of the laminar flow process area, which can meet the comfort requirements of personnel.
(3) The technical aisle can be used not only as a return air duct, but also to arrange various industrial pipelines and install process auxiliary equipment. The maintenance of local purification equipment (clean bench, clean shed, laminar flow hood, etc.), industrial pipelines and process auxiliary equipment that make up the clean tunnel can be carried out in the technical lane. Since the technical lane 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.
Local purification equipment, ceilings, wall panels, return air outlets, doors and windows and other components required for clean tunnels can be standardized and modularized, processed and produced by professional factories, and assembled on site. At the same time, the clean tunnel can be quickly disassembled and reassembled, which provides convenience for process changes.
(4) The clean tunnel can be equipped with a HVAC 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, clean tunnels have relatively simple architectural requirements, as long as they have a turbulent flow cleanroom environment, they can meet the requirements.
4、Cleanroom Pipe
The purification treatment method that puts the process line that requires an ultra-high cleanliness level (such as level 1 or level 10) in a pipeline that is isolated from the indoor air environment is called a clean pipeline. This method requires that the process production must be automated, and the high-efficiency filter must be based on 0.1μm dust particles to achieve ultra-high cleanliness. In addition, since the air to be purified is the air in the pipeline, the amount of air supply and return is very small, which can greatly save energy, which is the development direction of clean technology, also known as the fourth-generation purification method.
The purification treatment plan introduced above needs to be determined according to the specific situation. At present, the development of technology has been relatively mature. There are three purification treatment methods: whole room purification, local purification (including the combination of whole 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 situation.
Under the condition of meeting the process requirements, local purification methods should be selected as much as possible. Local purification adopts local purification equipment and is realized in a general air-conditioned environment. Since local purification equipment is generally produced by professional factories, the equipment is of high quality and can speed up on-site construction, so this scheme can be given priority in the reconstruction project.
When the process requirements cannot be met by only Local purification, the purification method combining local purification and whole room purification can be used as the design scheme.
When none of the above purification methods can meet the process requirements, the purification method of whole room purification is selected as the design scheme. Since this method requires the whole room to have the same cleanliness, especially when the cleanliness level is high, the initial investment and operating costs are very high. Therefore, the area of the cleanroom should be strictly controlled.