Patent Application
20230060403
The disclosed embodiments relate to a screen plate for a pulp screening machine, and additionally to a pulp screening machine with said screen plate.
There are usually welded or bolted (or a combination of both) wear strips on the surfaces of screen plates on pulp screening machines. The wear strips form as strip type projections to provide a cleaning function as well as a de-flaking function within the respective machine.
Drawbacks of such wear strips on the screen plate are that they wear out rather quickly, and the rotor must maintain a certain gap to the wear strips during assembly, which therefore results in an even larger gap between the rotor and the surface of the main body of the screen plate. Such a gap reduces screen plate cleaning efficiency, throughput, and de-flaking rate.
Disclosed herein are embodiments of a screen plate on a pulp screening machine that eliminate the shortcomings of the state of the art. The screen plate has concave grooves on the side of the main body facing towards the rotor of the pulp screening machine, wherein except in the grooved region, the rotor vane builds an even gap to the surface of the screen plate, wherein the rotor vane front edge of the pulp screening machine is arranged at an angle to the grooves.
Such grooves are arranged on the screen plate of the disclosed embodiments instead of conventional strip type projections as known in the art. Herein the grooves are not through grooves, but build up concave forms, in which the groove bottoms are slightly lower than the main body of the screen plate surface. Using grooves instead of projections allows a minimalization of the gap between the rotor and the surface of the screen plate, which increases the cleaning efficiency of the screen plate, throughput/yield of the pulp screening machine, as well as increases de-flaking efficiency. The smaller the gap between the rotor vanes and the surface of the screening plate outside the area of the grooves, the fewer impurities can enter into the gap between the rotor vanes and the screen plate, thus reducing wearing and improving life of the rotor and the screen plate.
An “even gap” formed between the grooved region and the surface of the screen plate means that except in the grooved region there is no substantial break, indentation, projection, or irregularity on the surface of the screen plate relative to the rotor. There might be slight difference in the width of gap occasionally, or even inclination, so long as such difference is an allowable tolerance in the conventional art. A purpose of replacing the conventional strip type projections on the screen plate with the grooves therein is to minimize the width of the gap. It is even possible for a technical solution with some protrusions on the screen plate to be regarded as an “even gap” as defined herein, as long as such protrusions do not substantially increase the width of the gap between the rotor vane and the surface of the screen plate.
According to one of the preferred embodiments, the grooves are designed to form angles greater than 90° relative to the front edge of the rotor vane along the entire length of the grooves, so as to avoid wedging—in of the impurities and facilitate the de-flaking of the impurities.
According to one of the preferred embodiments, the width of the grooves increases from a position at the center of the screen plate toward the outside of the screen plate. Due to the “wiping effect”, the amount of collected impurities on the rotor vane front edge increases from inside of the screen plate to the outside. The increased width of the grooves from the center of the screen plate to the outside adapts to such increasing amount of collected impurities.
According to one of the preferred embodiments, the depth of the grooves increases from a position at the center of the screen plate toward the outside of the screen plate. Due to the “wiping effect”, the amount of collected impurities on the rotor vane front edge increases from inside of the screen plate to the outside. The increased depth of the grooves from the center of the screen plate to the outside adapts to such increasing amount of collected impurities.
According to one of the preferred embodiments, the width and the depth of the grooves increases from the center of the screen plate to the outside. Due to the “wiping effect”, the amount of collected impurities on the rotor vane front edge increases from inside of the screen plate to outside. The increased width and depth of the grooves from the center of the screen plate to the outside adapts to such increasing amount of collected impurities.
According to one of the preferred embodiments in the present invention, the grooves have a larger width at their openings than at their bottoms. With such a groove design, fewer impurities are accumulated within the grooves.
According to one of the preferred embodiments, the screening plate is flat.
Preferably, both longitudinal ends of the grooves are open, so that the center of the screen plate is in communication with its peripheral region.
According to one of the preferred embodiments, the screen plate is curved.
Preferably, the screen plate is the cylindrical surface of the cylindrical screen basket.
Preferably, the screen plate is the conical surface of the conical screen basket.
Preferably, the screen plate (100) is perforated or slotted, whether it is flat or curved.
The present invention also provides a pulp screening machine comprising a rotor and an embodiment of the above described screen plate.
As shown, the width of each of the grooves 120 increases from the center of the screen plate toward the outside (the curved edge shown in
The advantages of the inventive embodiments disclosed herein are as follows: the grooves provided instead of projections as known in the art allows a minimization of the gap between the rotor and the screen plate, which increases de-flaking efficiency as well as capacity. This reduces buildup of impurities, especially larger impurities, because it is hard for the impurities to stay between the rotor and the screen plate, and the smaller gap restricts impurities from entering the gap. Accordingly, power consumption of the pulp screening machine decreases. Additionally, the lower amount of impurities entering into the gap between the rotor and the screen plate, wearing is reduced accordingly.
Alternatively, in an embodiment not shown, the surface of the screen plate can be configured to have a curved surface. For example, the screen plate may form a cylindrical surface of a cylindrical screen basket or a conical surface of a conical screen basket. Using grooves instead of projections on any shapes of screen plate yields the same advantages and improvements described above.
Moreover, although
The above discloses the preferable embodiments of this invention, while the spirit and scope of this invention are not limited within the specific contents disclosed here. Those skilled in the art can develop more embodiments and applications according to teaching of this invention, and these embodiments and applications also belong to the spirit and scope of this invention. Therefore, it could be understood that the specific embodiments of this invention do not further limit the spirit and scope of this invention, which is defined by the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111021314.6 | Sep 2021 | CN | national |
