Structurer Features of Pressure Screen

The pressure screen for pulp and paper machine is composed of a cylinder body, a transmission device, a sieve drum, a pressure screen rotor and related electrical parts. This screening equipment has four pipes: inlet pulp pipe; accepted pulp outlet; dilution water pipe and slag discharge pipe.

Working Principle Of Paper Pulp Pressure Screen

The slurry enters the pressure screen along a tangential direction at a certain pressure. Due to a certain pressure difference between the inside and outside of the drum，and when the rotor rotates, the gap between the inside of the rotor and the inner surface of the screen drum changes continuously. That is gradually from shrinking to larger, so that in each moment between the rotor and the sieve drum, in the front of the rotor form a positive pressure zone, the middle is the balance area, and the tail is the negative pressure area. In the negative pressure area, the good pulp outside the drum is washed back to play the role of self-cleaning, so as to keep the sieve open. When the slurry leaves the wing, the negative pressure disappears, and the good slurry flows again by another rotor, and begins the next cycle. The slurry falls into the lower part and is discharged through the slurry valve.

Working Principle of Medium Consistency Pressure Screen

During the operation of the screening equipment, the slurry enters the separation chamber on the upper part of the pressure screen along the tangential direction of the slurry pipe. The heavier impurities are separated under the action of centrifugal force, settling in the heavy slag tank and discharged by the heavy slag outlet. The slurry enters the screening area between the sieve drum and the rotary cylinder, the qualified fiber passes through the sieve drum and is discharged from the accepted output; the unqualified fiber continues to move downward and is discharged from the slag discharge pipe at the bottom of the cylinder body.

There is a dilution pipe opposite the slag outlet to adjust the concentration of the slurry. There are many convex blades on the surface of the revolving drum which rotates at the inside of the sieve drum in the pressure screen. When rotating, each blade produces negative pressure, so as to play the role of purifying the sieve drum, not to block the sieve drum.

Pressure of The Screening Equipment

The inlet pressure is generally between 0.1MPa and 0.4MPa, and the pressure difference between inlet and outlet is generally between 0.01MPa and 0.03MPa. The above data are related to the variety, quality, concentration, slurry flow rate and opening ratio of the sieve drum.