Strainer assembly for pulp

Claim 1

In an assembly for straining suspensions of solid pulp particles and including a strainer housing, a strainer drum rotatably mounted in the housing and having a substantially circular cylindrical mantle provided with strainer openings, said housing having an inlet for directing an incoming first stream of said suspension into a region in the housing outside said drum, an outlet for discharging a second stream which does not pass through the strainer openings, and an outlet for discharging a third stream which passes through said openings, said inlet being tangentially directed into the housing, and at least one impact plate member located in the strainer housing in position to subject solid particles in at least one of said first and second streams to an impact effect, thereby facilitating the separation between particles following said second and third streams, respectively, said impact plate member being attached to the housing and at an angle to the flow direction of said one stream, the improvement which comprises a device mounted in said inlet and attached to said housing for pivotal movement about an axis, said device having a plane forming an acute angle with the flow direction of said incoming first stream, and control means connected to said device and responsive to an increase in the flow pressure of said first stream against the plane of the device to reduce said angle, thereby providing a larger through-flow area for said first stream, said control means being responsive to a decrease in said flow pressure to increase said angle and thereby reduce said through-flow area.