The difference between positive pressure conveying and negative pressure conveying can be distinguished from the principle and scope of application of conveying:
1. Transport principle:
Positive pressure conveying is to use the fan at the starting point of the system to feed compressed air into the conveying pipeline, and make use of the pressure difference between the starting point and the end point of the pipeline to make the air flow in the pipeline and move with animal materials. In the positive pressure conveying system, the material is fed into the conveying system by the feeding device. At the end of conveying, the material is separated from the air.
Negative pressure conveying system is driven by the difference between negative pressure and external pressure formed by the ventilation device at the end of the conveying system. Because of the pressure difference, the outside air is sucked into the pipeline, and the material is brought into the pipeline along with the movement of the air. After reaching the end point, the material is separated from the air and collected, and the air is purified and discharged into the atmosphere or recycled.
Compared with the negative pressure pneumatic conveying system, the positive pressure conveying system has a longer conveying distance.
2. Scope of application:
Positive pressure conveying system is suitable for decentralized conveying, that is, one point to multi-point conveying. In the conveying pipeline, material can be separated by the gravity of material and conveying medium at any unloading point.
Negative pressure conveying system is mostly used for centralized conveying, that is, multi-point conveying to one point, such as dust removal in workshop, grain warehousing, etc. The advantage of negative pressure transportation is that it can effectively collect materials, which will not enter the atmosphere. This is especially important for the pneumatic transportation of toxic materials. However, due to the influence of vacuum, the distance of negative pressure transmission is limited to a certain extent. The limit of pressure drop in general system is O.044 MPaf71.