Equipment Description:Screening
To print this FactSheet click here To return to the FactSheet home page click here
Screening is used to remove contaminants from the pulp or stock suspension. The main types of screening are Coarse Screening, Fine Screening and Fractionation. Coarse Screening is used to remove larger contaminants such as grit and plastics. Fine Screening is generally used to remove smaller dirt specks and stickies. Fractionantion is used to split the stock into different streams with differing average fibre lengths in order that they can be treated or used differently later in the process. The screens used generallt contain a rotor and a screen basket. The rotor provides a mechanical force to keep the basket from blinding with stock as it passes through the basket and the basket provides the physical barrier to the contaminants whilst allowing the good fibre to pass through it. Normally the rotor rotates to provide the mechanical forces required but in special cases the rotor is stationary and the basket rotates. |
|
 Image courtesy of Metso |
Screens can be vertical or horizontal in design. Some older screen designs have a vibrating screen plate and no rotor. In most cases, Coarse screens contained perforated baskets, Fine Screens and Fractionators contain slotted baskets and vibrating screens can have either slotted or perforated plates. In a rotor and basket design, the rotor has foils that exert a pushing and pulling force on the basket surface to prevent stock blocking the basket surface. This force is determined by the foil design and the speed that the foil travels along the basket surface. This speed can be changed by altering the rotational speed of the rotor (or basket in the case of a centripetal screen). Most screens with a rotating rotor are of centrifugal design, i.e. the stock passes from inside to outside the basket. Most screens with a rotating basket are of centripetal design, i.e. the stock passes from outside the basket to inside the basket. There are also design where the rotor is outside the basket or double basket designs where the rotor sits between two baskets. |
Screening was also mentioned in the following Fact Sheets (13):
|
(This information is from suppliers listed in the Industry Directory. Contact PITA to have your company listed here) There are 0 other potential suppliers of relevant equipment/services. (This information is from suppliers listed in the Industry Directory Contact PITA to have your company listed here) |