Ductless fresh air system
The position of the exhaust vent in the clean room is determined by the production process, and the exhaust has the following functions:
① Eliminate harmful gases and dust emitted during the production process.
②Exhaust heat. For example, the exhaust in the clean operating room is to remove anesthetic gas, disinfection gas and bad smell; the exhaust in the tablet workshop is mainly to remove the dust generated during the production process; the exhaust in the small injection packaging process is to remove the combustion products and Generate heat. When designing an exhaust system, the calculation of exhaust air volume is similar to that in ventilation and air conditioning engineering.
How to scientifically design the exhaust system can not only meet the process requirements, but also save energy. Because the exhaust air volume increases, the fresh air volume also increases, and the energy consumption will inevitably increase.
Take the crushing and sieving clean room of the solid preparation workshop as an example to discuss the design method of the exhaust system. After the raw and auxiliary materials enter the production workshop, the process is crushing and sieving, and the dust generation point of the crushing process is mainly at the feeding port, the discharge port and the receiving device. If you are not familiar with this process, set the exhaust air according to the location of the dust generating point. Cover is also a method.
However, this method has a large exhaust volume (high energy consumption) and poor dust exhaust effect. The chemical dust will even diffuse throughout the room, which is very harmful to the health of workers. Therefore, if the method of exhausting air and dust is changed, the effect will be very different. The feeding port of the grinder does not produce much dust, and a small exhaust hood (300mmx300mm) is set to remove the dust emitted during feeding.
There is a lot of dust at the discharge port and the receiving bag. The rotation of the shredder blade is pressurized like a fan blade, so that the positive pressure generated there is very large, and it is difficult to effectively control the dust with a large exhaust hood. Therefore, according to this feature of the process, a closed receiving box can be installed at the discharge port, and a closed door and an exhaust port can be installed on the receiving box. As long as a small amount of exhaust air can generate negative pressure in the box.The key to the design of the exhaust system is the design of the exhaust (dust) program. Through a thorough understanding of the production process and familiarity with the characteristics of dust and heat generation, an effective heat capture and exhaust program (using a closed box, a closed chamber, and air Screen isolation plus exhaust hood, exhaust hood). However, all measures should not affect the production process operation, and should not increase the hidden danger of dust collection and dust generation in the clean room. That is to say, facilities such as dust exhaust, heat exhaust, and dust capture should not collect or produce dust.
