Multi-Stage Pressure Screen of paper machine - LDS

Multi-Stage Pressure Screen of paper machine

I. Overview

Being a new generation of LSS Series Upwash Pressurized Screen, LDS Series Multilevel Upwash Pressurized Screen contains three patented technologies, which can realize 2 to 4-level screening of stock with the same device. This greatly simplifies pulping flow and reduces chests, pumps and piping. While it reduces investment, it significantly decreases electricity consumption.

II. Working Principle

The stock goes through the bottom of LDS Series Multilevel Upwash Pressurized Screen and enters the first screening section. The heavy impurities which can damage the device enter the deslagging mouth at the bottom. The accepted stock enters next step after going through the first strainer drum (Level 1 screening section). The tailing discharged by the first strainer drum gets into the mixing and dilution area of Level 1 stock, which is between the first and second strainer drums. In this area, the dilution water from the outside of device and the tailing get fully mixed. Then they enter the second strainer drum (i.e. Level 2 screening section). The accepted stock passing the second strainer drum can go to next step directly or the first screening section for screening after mixing with the virgin pulp directly. The second-section tailing failed in passing the second strainer drum can be discharged directly or gets into the mixing and dilution section of Level 2 stock, which is between the second and third strainer drums. In this area, the dilution water from the outside of device gets fully mixed with the second-section tailing. Then they enter the third strainer drum (i.e. Level 3 screening section). The accepted stock which passes the third strainer drum returns to Level 2 screening section under the draining effect of dilution water which enters the mixing and dilution area of Level 1 stock. Depending on its utilization value, the tailing failed in passing the third strainer drum can be discharged directly or gets into the mixing and dilution area of Level 3 stock, which is between the third and fourth strainer drums. In this area, the dilution water from the outside of device and the tailing get fully mixed. Then they enter the fourth strainer drum (i.e. Level 4 screening section). The accepted stock which passes the fourth strainer drum returns to Level 3 screening section under the draining effect of dilution water which enter the mixing and dilution area of Level 2 stock. Because it has become useless, the tailing failed in passing the fourth strainer drum can be discharged out of the device directly through the deslagging piping.

III. Main Technical Parameters

The main technical parameters of LDS Series Multilevel Upwash Pressurized Screen depend on the types of stocks and technological requirements of pulping. The strainer drums are in two basic forms: hole screen and slotted screen whose minimum size reaches 0.08mm. The maximum capacity of single machine can reach 500T/D and the maximum screening area of Level 1 strainer drum of single machine can reach 8M². The power consumption varies with the types of strainer drums, screening levels, sizes of screening holes (slots), types of stocks and concentration of feeding pulp.

Pressure requirement for the pulp feeding LDS Series Multilevel Upwash Pressurized Screen: ≥0.1Mpa.

Pressure requirement for the dilution water: pressure of feeding pulp +≥0.05Mpa.

Concentration of Feeding Pulp: 0.1-3% (slotted screen) and 0.1-6% (hole screen).

IV. Structure and Features

The device is consisted of motor transmission system, rotor, strainer drums in the screening sections of Level 1 to multilevel, dilution and mixing areas of Level 1 to multilevel, one to two pipes for return flow pulp, one to three water inlets for dilution water, feeding pulp, heavy slag deslagging mouth, tailing deslagging mouth, etc. It can realize multilevel screening for paper pulp, particularly for the pulp regenerated from waste paper, resulting in very little fiber content in tailing pulp

LDS Series Multilevel Upwash Pressurized Screen has three national patented technologies on its rotor and housing, which enable very low power consumption and prevent impurities from tangling the rotor.