What is a pressure screen？

What is a pressure screen？

Pressure screen, essential process equipment for pulp and paper semen, field operators must be familiar with how it works, today we will briefly chat with the main design points of the pressure screen. The pressure screen is usually composed of the casing, screen frame, rotor (rotor), transmission system equipment and other important parts. According to its different functional characteristics, it has different designs: it is mainly divided into coarse screens according to the content of impurities in the slurry. It can be divided into general working pressure sieve, grading sieve and compound sieve according to the development of enterprise use and research purposes; according to the difference analysis of screen frame, it can be divided into hole sieve and slotted sieve; according to the different degrees of slurry flow to China, it can be divided into internal flow sieve Type sieve and external flow sieve. The key positions and parameters of the pressure screen are the rotor and rod. Most of the domestic use, due to the pressure from the inside to the outside of the single screen cylinder, so the following single-drum main outflow pressure screen is mainly introduced. For the factory operation managers of enterprises, the pressure screen is more concerned with the processing technical capacity, screen drum wear, slurry hanging and other issues, but they have little understanding of the basic theoretical knowledge of pressure screen design research. Only by understanding the characteristics of stress from the source to the screen can better practice and guide production and solve problems. The screen frame of the pressure screen is usually composed of the upper flange (including the locking bolt holes), the lower flange (including the fixed slot), the middle drum ring (some enterprise products are cross-structured grids), and bars. One of the core components of the screen frame is the rod, and the size of different rods varies greatly. Based on the above theoretical model, the design of the chamfers A and B can effectively reduce the local micro-turbulence, thereby increasing the effective throughput of the slurry. However, such a design is too finely adjusted, which requires the user to adjust the screen drum too much. Harsh, paper mills often do not have the ability to identify. The rotor can produce many teaching designs according to the difference of market demand. For example, the rotor system of the coarse screen is often designed as a barrel structure. The main research purpose is to reduce the entanglement of long impurities in the coarse screen slurry.

How to improve the mud handling ability without changing the rotor to improve the picture frame? The technical capacity of slurry processing increases with the decrease of the distance between the rotor/screen frame. Generally speaking, when the gap is 3mm, a higher slurry processing capacity can be obtained, because of the negative pressure of the rotor tail at this time, The screen gap backwashing effect is good, so the enterprise can effectively ensure its own throughput; when the distance is further reduced, according to the experimental research of different fluids, it is found that the development causes the positive pressure to increase and the negative pressure to drop, which seriously affects the self-cleaning effect of the screen frame. Therefore, the distance information between the rotor and the screen frame should be analyzed, detected and corrected for each shutdown.

Another online method is to screen the processing capacity. By reducing the thickened area at the bottom of the screen, the passing volume of the overall screen frame is increased (the heavy slag at the bottom of the screen has poor fluidity, and the area of the screen seam is seriously blocked). The side effect of this is that the processing load of the pressure screen system increases in the rear part, and it is necessary to optimize the processing capacity according to the slag-forming effect of the pressure screen two, three and the processing capacity. In order to alleviate the problem of heavy slag, many rotors are designed in a spiral or approximate spiral upward space shape, and an upward flow is formed during the rotation process of the rotor’s rotation inclination to partially offset the bottom enrichment effect.