Dust-free workshop air supply scheme：
Supply plan

Ordinary air conditioning air supply can be divided into centralized and local two types. In addition, the purification system needs coarse effect, medium effect and high efficiency filter, combined with the dual requirements of air conditioning and purification, purification air conditioning system can be divided into centralized purification air conditioning system and decentralized purification air conditioning system.

1, centralized purification air conditioning system

The primary effect and medium effect of air filter and heat and humidity treatment equipment (fan, heating, humidification and cooling equipment) are centrally arranged in an air conditioning room, and the system composed of pipes and high efficiency filters arranged in the indoor air inlet is called the centralized purification air conditioning system.

The air supply mode of centralized purification air conditioning system can be in the following forms.

(1) Single fan system

A. In order to prevent polluted air from infiltrating into the purification air conditioning system and polluting the air after the medium effect filter, the medium effect filter shao should generally be set in the positive pressure section of the system.

B. In order to prevent the air after the HEPA filter from being polluted again, the HEPA filter should be arranged at the end of the system as close as possible to the air supply port of the clean room. In general, it is not suitable to centrally arrange hePA filters in the air conditioning room or on the air supply pipe far from the air supply port of the clean room.

C. When the dust concentration in the return air is high or there is dust and fiber with large particle size, a medium-effect filter can be set on the return air outlet or return air pipeline.

D. Under the condition of tight enclosure structure, in order to prevent outdoor polluted air from entering the clean room from the fresh air outlet after the system stops running, in addition to setting a medium effect filter on the return air outlet or the return air pipeline, an electric closed valve can be set on the fresh air population pipeline and linked with the fan. When the fan starts, the closed valve is opened and closed when it stops running; Or set up a general regulating valve on the fresh air population pipeline, and add a medium effect filter.

(2) Set up the system of the on-duty fan

When the purification air conditioning system is in intermittent operation, in order to prevent the outdoor polluted air from entering the clean room through the gap of the envelope or the new tuyere after the system shutdown, the on-duty fan can be set up.

The air volume of the on-duty fan is determined by the number of air changes required to maintain the predetermined positive pressure value indoors; If the exhaust system in the clean room runs all day or reduces the air volume during non-production, the air volume of the fan on duty should also consider the exhaust volume of the exhaust system.

(3) Parallel centralized system

When multiple centralized purification air conditioning systems are arranged in an air conditioning room, several systems can be connected in parallel, and only one fresh air heat and humidity treatment system is set up. In this way, the cooling load and heat load of the air conditioning system in each centralized purification room can be reduced, and the operation is more flexible.

When the system runs normally, valve 1 and valve 3 are closed, valve 2 and valve 4 are opened, and fresh air fan 3 and air supply fan 5 are put into operation. When the system is on duty, valve 1 and valve 3 are opened, valve 2 and valve 4 are closed, fresh air fan 3 is put into operation, supply air fan 5 stops running. In addition, when a system does not need to run, valve 1 and valve 2 or valve 3 and valve 4 can be closed, the corresponding air supply fan also stops running, and the rest of the system can be used as usual.

(4) Double fan system

When the system resistance is large, in order to reduce noise, reduce air leakage and facilitate the operation and adjustment of the system, the technical and economic comparison of reasonable, can adopt the dual fan centralized purification air conditioning system

Because two fans are used in series, the efficiency of the double fan system is lower than that of each fan alone, and the area of the machine room is large.

(5) Two-stage hePA filter system. For laminar flow clean room, in order to prolong the service life of the top advanced filter, reduce its replacement times and improve the cleanliness of indoor air, a hePA filter can be added at the mouth of the air supply plenum or in the air conditioning room. The downside of this approach is that systemic resistance increases and investment increases accordingly.

(6) Part of the centralized system of direct air circulation using large centrifugal fan to achieve part of the centralized system of direct air circulation. A centralized system of direct air circulation is realized by using a small centrifugal fan in parallel. Laminar flow clean room air changes a lot, if the machine room and the distance of the clean room, can use large centrifugal fan or air volume, high wind pressure, several small high efficiency, low noise centrifugal fan in parallel, implementation to the nearest air direct cycle, shorten the length of the big duct, and saved the space of duct.

The small centrifugal fan and high efficiency filter composed of purification air supply unit, and then with the purification air supply unit composed of laminar flow clean room, the machine room covers an area smaller than the civil construction, the construction cycle will be greatly shortened.

(7) Centralized system for setting muffler. The system uses assembled clean chamber, local purification equipment (clean table, clean shed, laminar flow cover and self-purifier, etc.) and the general air conditioning environment constituted by the system, are called decentralized purification air conditioning system.

At present, the widely used form is the combination of centralized purification air conditioning system and decentralized purification air conditioning system. It has the advantages of centralized and decentralized system, and can better adapt to the requirements of process production and the objective conditions of construction engineering.

2, decentralized purification air conditioning system

The basic form of decentralized purification air conditioning system is as follows.

(1) In the centralized air conditioning system environment, set up local purification equipment.

(2) In the environment of decentralized air conditioning system, set up local purification equipment

Selection of air supply scheme

According to the requirements of clean room area, net height, location, noise reduction and vibration reduction, etc., after comprehensive technical and economic comparison, it is determined to adopt centralized purification air conditioning system or decentralized purification air conditioning system as the air supply scheme. In general, centralized system should be adopted for clean rooms with large area, high net height, centralized location and strict requirements for noise reduction and vibration reduction; Instead, a distributed system can be used.

In addition to the above principles, reconstruction projects can be treated differently according to the specific situation of the project. When the original building is equipped with a centralized air conditioning system, a centralized purification air conditioning system can be formed by adding a medium-effect filter and a high-efficiency filter in the air conditioning system or adding a high-efficiency filter at the air inlet, and improving the air volume and pressure of the fan by increasing the fan speed or replacing the fan. Local purification equipment can also be added indoors to form a decentralized purification air conditioning system.

If there is no air conditioning system in the original building, a centralized purification air conditioning system can be added; Purification air conditioners or small air conditioners and local purification equipment can also be added to form a decentralized purification air conditioning system.