Application of Screen Basket in Pressure Screen and Optimization
Pressure Screen Components
The screen basket, like the rotor, is the core of the pressure screen in pulping equipment. Pulp enters the pressure screen through the stock inlet. Under the pulsating action of the pressure screen rotor, fine fibers are screened through the screen slits on the screen basket surface, resulting in good-quality pulp. The pressure screen consists of a body, cover, screen basket, rotary drum, base, and transmission part, and the parts in contact with the slurry are all made of stainless steel. The pressure screen has a vertical cylindrical housing with a removable top cover. The housing is bolted to the base with the necessary connecting pipe flanges. The screen body and motor frame are bolted to the base. The housing houses the screen basket, the rotor and bearings are mounted within the screen basket, and the screen shaft is sealed with a mechanical seal.
Screen Basket Can be Divided Into Plate Type Corrugated Screen Baskets and Rod Type Corrugated Screen Baskets
The screen plates of plate type corrugated screen baskets are made of stainless steel and are available in two types: drilled screen baskets and slotted screen baskets. The surface of the screen plates in contact with the slurry is characterized by corrugated grooves, which facilitate the passage of fibers through the screen holes or slits, effectively separating qualified fibers from impurities and fiber clusters, thereby improving screening efficiency and producing high quality pulp. The screen plate is drilled, milled and polished, and the screen basket has a high surface finish. A reinforcement ring is welded on the outer surface of the screen basket, which gives the screen basket sufficient strength and rigidity. The upper end face is fixed to the cylinder by a flange with bolts, and the lower end is located in the cylinder for a firm connection and stable operation. The structure of the rod type corrugated screen basket is composed of hundreds of special wedge shaped rods, which are evenly embedded in the grooves on the circumference of the multi-layer annular plate along the circumferential direction. The upper side is connected to the cylinder with a flange surface, and the lower side is a cone. The surface of the screen basket is corrugated. The strength of the rods is greatly improved compared with the milled screen plate, especially after hardening treatment, it has a longer service life. It is an advanced structural form in the current papermaking industry.
Problem Optimization of the Screen Basket
The screening efficiency of the screen basket is low, the quality of the good pulp is not good, and the tail rotor loss is too large. It may be that the size of the screen basket is wrong and the effective screening area is insufficient. It is recommended to re-select a suitable screen basket according to the fiber length and the required purification accuracy. The opening rate and screening area of the screen basket will also affect the screening efficiency and production, which can be considered when selecting the screen basket.
When the pressure screen is running, the screen basket vibrates and makes abnormal noises. In severe cases, the screen basket may deform or crack. This may be caused by rotor imbalance or blade wear. The screen basket is not installed firmly, the fasteners fail, and hard foreign objects such as metal enter the screen area, causing impact damage. The above three may cause this phenomenon. It is recommended to stop the machine immediately to check for foreign objects, rotor wear and dynamic balance, and check whether the fasteners are in place.
If rust appears on the surface of the screen basket and the material becomes brittle, it may be that the pH value of the slurry is too high or too low, it is corrosive, or the cleaning chemicals are corrosive. It is recommended to monitor and neutralize the pH value of the slurry, avoid using strong corrosive chemicals when cleaning the screen basket, or rinse thoroughly after cleaning.
