The particle size range of PVC powder is large, from fine powder to large particles, with a bulk density of 0.27-0.8v/m ³. The material's conveying performance also varies greatly. In addition, it is sensitive to heat and also has electrostatic effects. In the 1970s and 1980s, low-pressure dilute phase pneumatic conveying was commonly used for PVC powder, which had many drawbacks. With the development of pneumatic conveying, especially the application of dense phase pneumatic conveying, pulse air knife pneumatic conveying and high concentration phase fluidized bed pump conveying have been commonly used in the past decade.

    As shown in the figure, it is a pulse air knife typePneumatic conveying systemThe system is a dual tank continuous pulse pneumatic conveying system that combines positive and negative pressure. It consists of two parts: the suction part, where PVC powder is manually poured into a circular vibrating screen for screening, and then transported through a suction nozzle and pipeline to the intermediate hopper of the cyclone unloader. The air source is a water ring vacuum pump; In the pressure feeding section, the material is sent into the upper sending tank through a pneumatic butterfly valve, while the lower sending tank is conveyed. When the material is conveyed to the lower feeding level, the balance valve opens, the pressure of the upper and lower sending tanks is balanced, the feed butterfly valve opens, and the material is sent into the lower sending tank. After a delay, the butterfly valve closes, and the upper tank exhausts and feeds, while the lower sending tank continues to operate continuouslytransportation.

    The main parameters of the system are: air knife pressure of 0.18MPa, sending tank pressure of 0.13MPa, pulse frequency of 21-26 times/min, good plug forming ability under the conditions of material gas time ratio (1:1.1)~(1:1.22), and actual conveying capacity of 4t/h.