Pressurized screen arrangement

Details Pressurized screen arrangement Pressurized screen arrangement

1995-08-07

1997-10-21

Lithgow, Thomas M.

Buckles, buttons, clasps, etc.

210450, 21049701, 209273, 209306, 209406, B07B 120, B01D 2935, B01D 2986

Patent

active

056792506

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a pressurized screen arrangement for the screening of lignocellulose-containing fibrous material, preferably in the form of a pulp suspension.


BACKGROUND OF THE INVENTION

A pressurized screen normally comprises three main parts, namely a screen housing, a screen cage, and a rotor. The screen cage is intended to act as a barrier for coarse material, while the fibers are allowed to pass through the screen apertures. The screen cage can be constructed, for example, of a perforated or slotted plate with a smooth or corrugated surface. Alternatively, the screen cage can be formed from spaced rods, through which the fibers, but not the impurities, can pass. It is, of course, essential that in order to obtain appropriate screening results, shortcircuiting be prevented, i.e. that unscreened material is not mixed with screened material
A conventional method of mounting the screen cage in the screen housing is to form rings at the ends of the screen cage. These rings have conical surfaces, which are fitted into corresponding conical seats in flanges in the screen housing. These conical surfaces, in combination with axial prestressing, create significant limitations on the potential radial motion (translation) and tangential angular movement (rotational) of the end portions of the screen cage.
In order to prevent clogging of the screen cage, a rotor which produces suction and pressure pulses is used. These pulses create radially directed forces along the circumference of the screen cage. These forces cause a statically determined radial movement of the shell surface of the screen cage. Owing to the aforementioned prestressing, however, the end portions of the screen cage cannot be moved in this manner. Due to their design, the end portions are thus forced to assume a shape determined by the conical rings fitted into the conical seats. This deformation at the end portions causes stresses in the material itself. These stresses are secondary by nature, but due to the dynamic character of the load, they are totally decisive in determining the service life of the screen cage. The size of these forces depends on various factors, such as the rotor design, the consistency of the fibrous material, etc.


SUMMARY OF THE INVENTION

In accordance with the present invention, these and other objects have now been accomplished by the invention of apparatus for screening lignocellulose-containing fibrous material comprising a housing, a screen cage mounted in the housing, the screen cage having a first end and a second end, a rotor mounted within the screen cage, the housing including first attachment means at a first end of the screen cage and second attachment means at a second end of the screen cage, mounting means for mounting the first end of the screen cage on the first attachment means while providing radial clearance therebetween so as to permit radial motion of the screen cage at the first attachment means and for mounting the second end of the screen cage on the second attachment means while providing radial clearance therebetween so to permit radial motion of the screen cage at the second attachment means, and axial support means for axially supporting at least one of the first and second attachment means.
In accordance with one embodiment of the apparatus of the present invention, the apparatus includes rotation prevention means extending between at least one of the first and second attachment means and the screen cage for preventing rotation of the screen cage within the housing.
In accordance with another embodiment of the apparatus of the present invention, the screen cage comprises a perforated or slotted plate. In another embodiment the screen cage comprises a plurality of rods, and includes a plurality of support strips extending around those rods.
In accordance with another embodiment of the apparatus of the present invention, the apparatus includes separate seal means provided in the radial clearance between the first and second attachment means and the

REFERENCES:
patent: 3034650 (1962-05-01), Szepan
patent: 3700110 (1972-10-01), Engalitcheff
patent: 3786918 (1974-01-01), Holz
patent: 3953325 (1976-04-01), Nelson
patent: 4017387 (1977-04-01), Hatton
patent: 4188286 (1980-02-01), Holz
patent: 4252641 (1981-02-01), Martin
patent: 4410424 (1983-10-01), Chupka
patent: 4507201 (1985-03-01), Wall
patent: 4846971 (1989-07-01), Lamort
patent: 5271837 (1993-12-01), Discepolo
patent: 5326470 (1994-07-01), Shaw

Affiliated with

Also associated with

Rating

Pressurized screen arrangement does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Pressurized screen arrangement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pressurized screen arrangement will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1004005