阅读说明：本技术 筛浆机 (Pulp screening machine ) 是由 亚历山大·葛帅德 于 2021-09-01 设计创作，主要内容包括：本发明涉及一种筛浆机,该筛浆机包括：从所述筛浆机的底部向上突伸的筛网(200)和围绕所述筛网外侧转动的转子(100),其中,所述筛浆机的出浆口布置在筛网(200)内侧,进浆口和浆渣出口布置在筛网(200)外侧,其中,所述转子(100)的转子叶片(101)从位于所述筛网(200)顶部的转子基体(102)悬臂式地延伸至所述筛网(200)的区域,且所述转子叶片(101)在所述筛网(200)的区域内彼此不相互连接,其中,所述转子叶片(101)具有适于与所述筛网(200)的外侧表面共同实现疏解作用的刚度。(The invention relates to a pulp screening machine, comprising: a screen (200) protruding upwards from the bottom of the screen and a rotor (100) rotating around the outside of the screen, wherein the pulp outlet of the screen is arranged inside the screen (200) and the pulp inlet and the reject outlet are arranged outside the screen (200), wherein the rotor blades (101) of the rotor (100) extend cantilevered from a rotor base body (102) on top of the screen (200) to the area of the screen (200) and the rotor blades (101) are not interconnected to each other in the area of the screen (200), wherein the rotor blades (101) have a stiffness adapted to achieve a defibering effect in cooperation with the outside surface of the screen (200).)

1. A screen, characterized in that the screen comprises: a screen (200) protruding upwards from the bottom of the screen and a rotor (100) rotating around the outside of the screen, wherein the pulp outlet of the screen is arranged inside the screen (200) and the pulp inlet and the reject outlet are arranged outside the screen (200), wherein the rotor blades (101) of the rotor (100) extend cantilevered from a rotor base body (102) on top of the screen (200) to the area of the screen (200) and the rotor blades (101) are not interconnected to each other in the area of the screen (200), wherein the rotor blades (101) have a stiffness adapted to achieve a defibering effect in cooperation with the outside surface of the screen (200).

2. A screen as claimed in claim 1, characterized in that the screen cloth (200) of the screen is cylindrical projecting vertically upwards.

3. A screen as claimed in claim 1, characterized in that the screen cloth (200) of the screen is in the shape of a cone, which widens gradually upwards.

4. A pulp screen as claimed in claim 1, characterized in that the screen cloth (200) of the pulp screen is in the shape of a cone tapering upwards.

5. A screen as claimed in claim 1, characterized in that the screen of the screen forms an angle α with the horizontal of more than 90 ° and 135 ° or less.

6. A screen as claimed in claim 1, characterized in that the screen of the screen forms an angle α with the horizontal of more than or equal to 45 ° and less than 90 °.

7. A screen as claimed in claim 5, characterized in that the screen cloth of the screen forms an angle α with the horizontal plane which is greater than 90 ° and equal to or less than 105 °.

8. A screen as claimed in claim 6, characterized in that the screen cloth of the screen forms an angle α with the horizontal plane of more than or equal to 75 ° and less than 90 °.

9. A screen as claimed in any one of claims 1 to 8, characterized in that the screen cloth (200) of the screen has raised ribs (210) on its outer surface.

10. A screen as claimed in claim 9, characterized in that the raised ribs (210) on the outer side surface of the screen cloth (200) of the screen are arranged at an angle to the blade leading edge (110) of the rotor.

11. A screen as claimed in claim 10, characterized in that on the outer surface of the screen's screen cloth (200), the ribs (210) have the same extension in the height of the screen cloth as the rotor's blade leading edges (110).

12. A screen as claimed in claim 11, characterized in that the height of the screen is covered by sets of ribs (210) arranged on the outer side surface of the screen (200) of the screen.

13. A screen as claimed in any one of claims 1 to 8, characterized in that the outer surface of the screen cloth (200) of the screen has concave grooves (220).

14. A screen as claimed in claim 13, characterized in that the recessed grooves (220) on the outer side surface of the screen cloth (200) of the screen are arranged at an angle to the blade leading edge (110) of the rotor.

15. A screen as claimed in claim 13, characterized in that the width of the grooves (220) increases gradually from the top to the bottom of the screen (200).

16. A screen as claimed in claim 13, characterized in that the depth of the grooves (220) increases gradually from the top to the bottom of the screen (200).

17. A screen as claimed in claim 13, characterized in that the width and depth of the grooves (220) gradually increase from the top to the bottom of the screen (200).

18. A screen as claimed in claim 14, characterized in that on the outer surface of the screen's screen (200), the grooves (220) have the same extension in the height of the screen as the rotor's blade leading edges (110).

19. A screen as claimed in claim 18, characterized in that the height of the screen is covered by sets of grooves (220) arranged on the outer surface of the screen (200) of the screen.

20. A screen pulp machine according to any one of claims 1-8, characterized in that the screen cloth (200) is an aperture screen.

21. A screen pulp machine according to any one of claims 1-8, characterized in that the screen cloth (200) is a slotted screen.

22. A screen as claimed in claim 21, characterized in that the screen slots of the screen cloth (200) are arranged at an angle to the blade leading edge (110) of the rotor.

23. A screen as claimed in claim 21, characterized in that the screen slots of the screen cloth (200) are arranged at an angle to the rotation axis of the rotor.

24. A screen as claimed in any one of claims 1 to 8, characterized in that the casing of the screen has a tangentially arranged reject collector for catching heavy impurities.

Technical Field

The invention relates to a screen for screening fibre suspensions.

Background

Screening of fiber suspensions is a common procedure in the paper industry and is particularly important for recycling fibers. Depending on the application, different types of screens are usually required.

For strong, hard-to-pulp furnish (e.g., furnish containing unbleached kraft fiber), disc screens are used primarily. Conventional disc screens generally have a flat screen plate and a disc rotor with a plurality of blades. Disc screens may provide higher fluffing efficiency than basket screens. Although these disc screens operate at a higher energy consumption, they are still widely used in the industry due to the high fiber production.

These disc screens have, in addition to the high electrical energy consumption (mainly due to the high tip speed of the rotor blades), other drawbacks, on the one hand, the relatively rapid wear of the rotor and screen plates (and even of the screen shell) of the disc screens, with the consequent serious consequences of a significant reduction in the working capacity of the disc screens and a reduction in the production, since the conditions of the screen plates vary greatly from inside the screen plate (close to the hub) to outside after a significant wear, since the tip speed is a function of the radius, the outer zone has a higher tip speed, and at the same time the throughput is higher, so that the wear of the outer zone is also the fastest. Another disadvantage is also that a larger volume of machine equipment is required, since the screening area of the flat screening deck is relatively small compared to basket screens.

Fig. 7 and 8 show a prior art internal flow screen with rotor blades arranged outside the basket screen. The rotor blades 101 are typically of hydrofoil design and are very flexible, as shown in cross-section in FIG. 8. The thick arrows in fig. 7 and 8 show the direction of rotation of the screen, while the thin arrows schematically show the flow into and out of the screen caused by the hydrofoil profile of the rotor blades 101. The rotor blades are interconnected by an annular member 103 as shown in fig. 7. This design avoids the overhang of the rotor blade, ensures the stable position of the rotor blade, but is not suitable for screening the slurry which has just passed through the coarse screen because the annular member easily causes the winding and accumulation of impurities. This design is therefore suitable for applications where it is not necessary to provide significant fluffing, i.e. where a low coarse impurity content of the slurry itself is required. A screen of this design is used in a pulp flow screening or fine screening system in the field of paper machines (after having been coarse screened).

Disclosure of Invention

To overcome the above-mentioned drawbacks of the prior art, the present invention provides a pulp screen comprising: a screen projecting upwards from the bottom of the screen and a rotor rotating around the outside of the screen, wherein the outlet of the screen is arranged inside the screen and the inlet and the reject outlet are arranged outside the screen, wherein the rotor blades of the rotor extend cantilevered from the rotor base at the top of the screen to the area of the screen and are not interconnected to each other in the area of the screen. Wherein the rotor blade has a stiffness adapted to achieve a defibering effect in cooperation with an outer side surface of the screen.

In contrast to the prior art, the screen of the present invention replaces the planar screen deck with a basket-type screen, the disc-shaped rotor being designed with a similar airfoil geometry but with rotor blades arranged outside the screen. Since the inlet is arranged outside the screen and the outlet is arranged inside the screen, the accept flows towards the inside of the screen while the reject is retained outside the screen, preferably tangentially, leaving the screen from the reject outlet, which is also designed outside the screen. Compared with the prior art that the pulp inlet is arranged on the inner side of the screen and the pulp outlet is arranged on the outer side of the screen, the inward flow type design has the beneficial effect that the abrasion on the inner side of the screen caused by centrifugal force is reduced. Heavy impurities, which cause severe wear to the screen, are no longer located in the screen. Furthermore, heavy impurities can be collected by a tangentially arranged waste collector mounted on the screen casing.

The inventors have first noticed that since the rotor blades overhanging the screen area are not connected to each other, and no annular member is provided, entanglement and accumulation of foreign matter can be avoided as much as possible. The rotor blade now has a certain flexibility and the sheets of paper (fibre mass) that have not been pulped can be fluffed between the overhanging rotor blade and the screen. The inventive pulp screen can thus achieve a further defibering of the pulp and removal of coarse impurities at the cost of a minimum fibre loss, immediately after the pulping step of the so-called coarse screening system.

The screen mesh of the pulp screening machine can be in a cylindrical shape protruding vertically upwards, or in a conical cylinder shape gradually widening upwards or narrowing upwards. The rotor blades sweep the screen surface in a mating shape.

According to a preferred embodiment of the screen according to the invention, the screen has raised ribs on its outer surface. The raised ribs are preferably made of wear-resistant material, so that the raised ribs have a good wear-resistant effect, the fluffing capacity of the pulp screening machine is further improved, and waste materials are prevented from accumulating between the rotor and the screen. The ribs preferably have sharp edges to increase fluffing and reduce energy consumption. The ribs may be separate members bolted, welded or otherwise assembled to the outer surface of the screen panel or may be integrally formed on the outer surface of the screen panel.

Preferably, the raised ribs on the outer surface of the screen are arranged at an angle to the leading edge of the blades of the rotor. It is further preferred that the ribs are arranged at an angle of more than 90 degrees to the leading edge of the blade. Of course, it is also conceivable to arrange the ribs perpendicular to the blades or at other angles. Angles greater than 90 degrees reduce wear; while angles less than 90 degrees will improve fluffing efficiency.

Preferably, the ribs have substantially the same extension over the height of the screen as the leading edges of the blades of the rotor on the outer surface of the screen, so that the fluffing effect is increased over the entire height of the screen.

Each rib may be designed as a single rib spanning the height of the screen. It is preferred that the height of the screen is covered by sets of ribs arranged on the outer surface of the screen.

In addition, within the scope of the invention, it is also possible to replace the raised ribs on the screen with recessed grooves on the outer surface of the screen, so that the rotor blades can be closer to the screen, thus giving the screen a better fluffing effect and a higher working efficiency.

Obviously, the grooves have bottoms, which are not through slots. The raised ribs are placed in locations where there are no holes or slots, but the grooves can be placed in areas where there are holes to provide more open area to increase production.

According to a preferred embodiment of the invention, the width of the grooves increases gradually from the top (slurry inlet end) to the bottom (slag discharge end) of the screen. The amount of impurities accumulated on the leading edge of the rotor blade will gradually increase from the top of the screen towards the bottom due to the "sweeping effect". The gradual increase in the width of the grooves from the top of the screen to the bottom of the screen is compatible with the gradual increase in the amount of accumulated impurities.

According to a preferred embodiment of the invention, the depth of the grooves increases from the top (slurry inlet end) to the bottom (slag discharge end) of the screen. The amount of impurities accumulated on the leading edge of the rotor blade will gradually increase from the top of the screen towards the bottom due to the "sweeping effect". The gradual increase in the depth of the grooves from the top of the screen to the bottom of the screen is compatible with the gradual increase in the amount of accumulated impurities.

According to a preferred embodiment of the invention, the width and depth of the grooves increase gradually from the top (slurry inlet end) to the bottom (slag discharge end) of the screen. The amount of impurities accumulated on the leading edge of the rotor blade will gradually increase from the top of the screen towards the bottom due to the "sweeping effect". The gradual increase in both the width and depth of the grooves from the top of the screen to the bottom of the screen is compatible with the gradual increase in the amount of accumulated impurities.

Similarly, the recessed grooves on the outer surface of the screen are arranged at an angle to the leading edge of the blades of the rotor. It is further preferred that the groove is arranged at an angle of more than 90 degrees to the leading edge of the blade. Of course, it is also contemplated that the grooves may be disposed perpendicular to the blades or at other angles.

Preferably, the grooves have substantially the same extension over the height of the screen as the leading edges of the blades of the rotor on the outer surface of the screen, so that the defibering effect is increased over the entire height of the screen.

Each groove may be designed as a single groove spanning the height of the screen. But it is preferred that the height of the screen is covered by sets of the grooves arranged on the outer surface of the screen.

The screen is a hole screen or a slot screen. For screens designed as slotted screens, the screen slots are preferably arranged at an angle to the leading edge of the blades of the rotor. The screen slots and the rotating shaft are arranged at a certain angle, so that the conveying capacity of the slurry and impurities from the feed inlet to the slurry residue outlet is improved, and the screen basket is kept clean.

The pulp screening machine has the beneficial effects that: firstly, the ratio of the size of the provided screen area to the size of the pulp screen is greatly improved compared with that of a plane sieve plate, and the size of the pulp screen is smaller under the condition of the same capacity; secondly, the power consumption is reduced due to the fact that the screen area is fully utilized and the tip speed of the blades is reduced; moreover, due to the application of the reduced tip velocity and inflow principle (in-flow principle), the wear of the screen due to centrifugal force is greatly reduced, and heavy impurities can be removed outside the screen without remaining inside the screen; furthermore, since the rotor is arranged outside the screen basket, the rotor or the rotor blades can be easily replaced.

Drawings

Fig. 1 schematically shows a cross-sectional view of a screen according to an embodiment of the invention, in which only the screen and the rotor are shown;

figure 2 schematically shows a cross-sectional view of a screen according to another embodiment of the invention, in which only the screen and the rotor are shown;

figure 3 schematically shows a cross-sectional view of a screen according to a further embodiment of the invention, in which only the screen and the rotor are shown;

figure 4 shows schematically in a perspective view a rotor and a screen of a screen according to the invention;

figure 5 shows schematically in a perspective view a raised rib on the outside of a screen of a pulp screen according to the invention;

figure 6 schematically shows a screen and a rotor of a screen according to the invention;

figure 7 shows schematically a rotor corresponding to a basket screen according to the prior art;

fig. 8 schematically shows a partial cross-sectional view of a rotor blade and a basket screen of the rotor shown in fig. 7.

Detailed Description

Fig. 1 schematically shows a cross-sectional view of a screen according to an embodiment of the invention, in which only a screen basket of the screen basket type and a rotor are shown. As shown, the screen 200 of the screen is in the shape of a cone tapering upwards, and the rotor 100 rotates around the outside of the screen 200, wherein the pulp outlet (not shown) of the screen is arranged inside the screen 200, and the pulp inlet (not shown) and the reject outlet (not shown) are arranged outside the screen 200.

Fig. 2 schematically shows a cross-sectional view of a screen according to another embodiment of the invention, in which only the screen and the rotor are shown. As shown, the screen 200 of the screen has a cylindrical shape protruding vertically upward, and the rotor 100 rotates around the outside of the screen 200.

Fig. 3 schematically shows a cross-sectional view of a screen according to another embodiment of the invention, in which only the screen and the rotor are shown. As shown, the screen 200 of the screen has a conical cylinder shape gradually widening upward, and the rotor 100 rotates around the outside of the screen 200.

The screen angle alpha, i.e. the angle which the screen as shown in fig. 1 to 3 makes with the horizontal plane, is between 45 deg. and 135 deg., preferably between 75 deg. and 105 deg., depending on the furnish used and the application scenario. The inventors have noted that the fluffing power is increased when the angle α is less than 90 °, and the accepts quality is improved when the angle α is greater than 90 °.

Under similar fluffing effect, the end speed of the rotor blade of the pulp screen of the invention is reduced by up to 30% compared with the disc type pulp screen in the prior art, which can obviously reduce the energy consumption and prolong the service life of the screen basket and the rotor.

Figure 4 shows schematically in a perspective view a rotor and a screen of a screen according to the invention. The rotor 100 is shown as being wrapped around the outside of the screen 200. The outside of the screen 200 is provided with raised ribs 210. The ribs 210 serve to enhance fluffing and avoid the accumulation of waste (impurities) between the rotor and the screen. In various embodiments, grooves may be used instead of ribs to achieve similar technical effects. Fig. 5 shows schematically in a perspective view another screen of a screen according to the invention, the outside of the screen 200 being provided with recessed grooves 220.

Depending on the pulp preparation and application scenario, a screen-slot type screen basket may also be used, which may improve accepts quality while maintaining high fluffing efficiency. The screen slots 230 are arranged at an angle to the axis of rotation, increasing the transport capacity of the slurry and impurities from the feed inlet to the reject outlet and keeping the screen basket clean. Figure 6 schematically shows a screen and a rotor of a screen according to the invention. Where the screen is a slotted screen, one of the screen slots 230 is shown in the figure as an example on the outside surface of the screen. The screen slots 230 are arranged at an angle to the blade leading edge 110 of the rotor.

Although the invention has been described with reference to specific embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Those skilled in the art can develop further embodiments and specific applications from the teachings of this invention that fall within the spirit and scope of this invention. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

List of reference numerals

100 rotor

101 rotor blade

102 rotor base

103 annular member

110 leading edge of rotor blade

200 mesh screen

210 raised ribs

220 recessed groove

230 screen slots.