Abstract: An apparatus for screening a suspension of fibrous cellulose pulp comprising a housing and a rotor shaft, the housing having an inlet for the suspension and containing first and second screening sections, each comprising a rotor member mounted on the rotor shaft and a cylindrical screen cooperating therewith and defining an outer accept chamber and an inner screening chamber, the first screening section including an inlet chamber communicating with the screening chamber of the first screening section, and an outlet chamber communicating with the screening chamber of the first screening section, for discharging a first reject, and the second screening section including an outlet chamber communicating with the screening chamber of the second screening section, for discharging a second reject from the apparatus, and the accept chamber of the second screening section having an outlet for discharging screened fiber suspension.

Abstract: A method of delignification of cellulosic fiber material is described. The pulp containing said cellulosic fiber material is fed in a main line containing a main reactor in which the pulp is treated with oxygen. The pulp is screened at at lest one point in the main line, and the screen reject obtained is fed in a branch line containing at least one secondary reactor for separate treatment with oxygen. According to the invention the separate treatment with oxygen is carried out without previous refining, and the screen reject thus separately treated in said branch line is returned to the main line at a point upstream of said main reactor.

Abstract: A device for screening fluidizable suspensions, such as medium consistency (e.g. 6-15 percent solids) paper pulp includes a housing with a main suspension inlet and a main (rejects) outlet. A rotor having a plurality of ribs is mounted in the housing for rotation about an axis. A stationary screen is disposed in the housing between the main inlet and outlet. The stationary screen defines, with the housing, a chamber, and the rotor is positioned so that the ribs sweep past the screen, with only a small clearance between the screen and ribs. Between the screen and the outlet grinding elements are provided, comprising a stationary grinding ring connected to the housing, and a movable grinding ring connected to the rotor for rotation with the rotor. The grinding elements define a grinding slot between them. The grinding slot is adjustable either by replacing one or both of the grinding rings, or by forming the grinding elements so that they are conical and adjusting the axial position of the rotor in the housing.

Abstract: A device for screening fluidizible suspensions, such as medium consistency (e.g. 6-15 percent solids) paper pulp includes a housing with a main suspension inlet and a main (rejects) outlet. A rotor having a plurality of ribs is mounted in the housing for rotation about an axis. A stationary screen, which may be a planar screen or a cylinder, is disposed in the housing between the main inlet and outlet. The stationary screen defines, with the housing, a chamber, and the rotor is positioned so that the ribs sweep past the screen, with only a small clearance between the screen and ribs. One or more dividing walls divide the chamber into a plurality of accept chambers, the dividing wall(s) extending radially when the screen is cylindrical, and parallel to the axis of rotation when the screen is planar. Dilution liquid may be added at the wall area between accept chambers. A rotor in the shape of a drum is used with the cylindrical screen, and a disc shaped rotor with the planar screen.

Abstract: A simple mixing apparatus provides especially for the mixing of treatment fluids with suspensions having a consistency of about 2-15%. First and second cylindrical coaxial housing parts are provided, the second part having a larger diameter than the first part. A fluid inlet introduces fluid axially into the first housing part, and a fluid outlet expels treated fluid tangentially from the second housing part. Stirring and mixing is provided by first and second stirring members rotatable about a common axis, the first stirring member having a number of axially extending, radially upstanding ribs cooperating with similar ribs on the interior of the first housing part, and the second stirring member having a number of radially extending, axially upstanding ribs cooperating with like ribs formed in the second housing part. The suspension is fluidized by the stirring members, and the residence time of suspension with the apparatus is between about 0.01 and 2.0 seconds.