Pulp screening machine
By designing an in-flow screening machine, using a screen basket screen and a rotor blade with airfoil geometric shape, the existing disc screening problem is solved, and the efficient and low-energy-consuming fiber suspension screening effect is achieved.
Patent Information
- Application Number
- CN202411984561.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2021-09-01
- Publication Date
- 2025-04-01
AI Technical Summary
The existing disc screens consume high energy during fiber suspension screening, and the rotor and screen plate wear quickly, resulting in a decrease in working capacity, large equipment size and low efficiency.
An intraflow slurry slurry is designed, using a screen basket screen and a rotor blade with a wing-shaped geometric shape. The rotor blades cantilever extend to the screen area and are not connected to each other. The inlet port is on the outside of the screen and the outlet port is on the inside of the screen. The inflow principle is used to reduce centrifugal wear.
It reduces the wear of screens caused by centrifugal force, improves the relocation efficiency, reduces energy consumption, extends the service life of the equipment, effectively removes heavy impurities, and improves the cleanliness of the slurry.
Smart Images
Figure CN119736810A_ABST
Abstract
Description
[0001] This application is a divisional application of the Chinese invention patent application filed by the present applicant, with application date of September 1, 2021, application number 202111021322.0, and invention name “Pulp Screening Machine”. Technical Field
[0002] The invention relates to a pulp screening machine which is used for screening fiber suspension. Background Art
[0003] Screening of fiber suspension is a common process in the papermaking industry and is particularly important for recycled fibers. Depending on the application environment, different types of screens are usually required.
[0004] For high-strength, hard-to-break pulps (e.g., pulps containing unbleached kraft fibers), disc screens are primarily used. Common disc screens generally have a flat screen plate and a disc rotor with multiple blades. Compared to basket screens, disc screens can provide higher deflaking efficiency. Although these disc screens consume more energy to operate, they are still widely used in the industry due to their high fiber production.
[0005] In addition to high power consumption (mainly due to high rotor blade tip speed), these disc screens have many other defects. On the one hand, the rotor and screen plate (even the pulp screen housing) of the disc screen wear quickly, which has the serious consequence of significantly reducing the working capacity of the disc screen and reducing production. The reason is that after severe wear, the condition of the screen plate will change greatly from the inside of the screen plate (near the hub) to the outside. Because the tip speed is a function of the radius, the outer area has a higher tip speed and a higher throughput, which causes the outer area to wear the fastest. Another defect is that a larger machine is required because the screening area of the flat screen plate is relatively small compared to the basket screen.
[0006] Figure 7 and Figure 8 The figure shows an inflow pulp screen in the prior art in which rotor blades are arranged outside the screen basket screen. The rotor blades 101 are usually of a hydraulic airfoil design and are very flexible. Figure 8 shown. Figure 7 and Figure 8 The thick arrows in the figure show the direction of rotation of the screen, while the thin arrows schematically show the flow in and out of the screen caused by the hydraulic airfoil of the rotor blades 101. Figure 7As shown, the rotor blades are connected to each other by an annular member 103. This design avoids the overhang of the rotor blades and ensures the stable position of the rotor blades, but is not suitable for screening the pulp that has just passed the coarse screen because the annular member easily causes the impurities to be entangled and accumulated. Therefore, this design is suitable for occasions where it is not necessary to provide a significant debonding effect, that is, the pulp itself is required to have a low content of coarse impurities. The pulp screening machine of this design is used in the pulp flow screening or fine screening system in the field of papermaking machinery (after the coarse screening has been performed). Summary of the invention
[0007] In order to overcome the above-mentioned shortcomings of the prior art, the present invention provides a pulp screening machine, which includes: a screen protruding upward from the bottom of the pulp screening machine and a rotor rotating around the outside of the screen, wherein the pulp outlet of the pulp screening machine is arranged on the inside of the screen, and the pulp inlet and pulp residue outlet are arranged on the outside of the screen, wherein the rotor blades of the rotor extend from the rotor base located on the top of the screen to the area of the screen in a cantilevered manner, and the rotor blades are not connected to each other in the area of the screen. The rotor blades have a rigidity suitable for achieving a debonding effect together with the outer surface of the screen.
[0008] Different from the prior art, the pulp screen of the present invention uses a screen basket-type screen to replace the flat screen plate, and the disc-shaped rotor adopts a similar airfoil geometry design but the rotor blades are arranged on the outside of the screen. Since the pulp inlet is arranged on the outside of the screen and the pulp outlet is arranged on the inside of the screen, the good pulp flows to the inside of the screen, while the pulp residue is blocked on the outside of the screen and preferably leaves the pulp screen along the tangent direction from the pulp residue outlet also designed on the outside of the screen. Such an "inward flow" design has the beneficial effect of reducing the wear on the inside of the screen caused by centrifugal force compared to the prior art in which the pulp inlet is on the inside of the screen and the pulp outlet is on the outside of the screen. Heavy impurities that would cause severe wear to the screen are no longer located in the screen. Moreover, heavy impurities can be centrally captured by a waste collector arranged along the tangent installed on the pulp screen housing.
[0009] The inventors first noticed that since the rotor blades overhanging into the screen area are not connected to each other and no annular member is provided, the entanglement and accumulation of impurities can be avoided as much as possible. At this time, the rotor blades have a certain flexibility, and the paper pieces (fiber blocks) that have not been beaten into pulp can be de-pulped between the overhanging rotor blades and the screen. Therefore, the pulp screen of the present invention can be immediately connected to the pulping step of the so-called coarse screening system to further de-pulp the pulp and remove the coarse impurities at the cost of minimum fiber loss.
[0010] The screen of the pulp screening machine can be in the shape of a cylinder protruding vertically upward, or in the shape of a cone gradually widening upward, or in the shape of a cone gradually narrowing upward. The rotor blades sweep across the surface of the screen in a matching shape.
[0011] According to a preferred embodiment of the pulp screen of the present invention, the outer surface of the screen of the pulp screen has raised ribs. These raised ribs are preferably made of wear-resistant material, have good anti-wear effect, further improve the fluffering ability of the pulp screen and avoid waste accumulation between the rotor and the screen. The ribs preferably have sharp edges to increase the fluffering effect and reduce energy consumption. The ribs can be additional separate components installed on the outer surface of the screen by bolt connection, welding or combination, or can be formed integrally on the outer surface of the screen.
[0012] Preferably, the raised ribs on the outer surface of the screen of the pulp screen are arranged at an angle to the leading edge of the blade of the rotor. Further preferably, the ribs are arranged at an angle greater than 90 degrees to the leading edge of the blade. Of course, it is also possible to consider arranging the ribs perpendicular to the blade or at other angles. An angle greater than 90 degrees will reduce wear; while an angle less than 90 degrees will improve the debonding efficiency.
[0013] Preferably, on the outer surface of the screen of the pulp screen, the ribs and the leading edges of the blades of the rotor have substantially the same extension range at the height of the screen, thereby improving the deflaking effect over the entire height of the screen.
[0014] Each rib can be designed as a single rib spanning the height of the screen. However, it is preferred that a plurality of groups of ribs arranged on the outer surface of the screen of the pulp screen cover the height of the screen.
[0015] In addition, within the scope of the present invention, the raised ribs on the screen can be replaced by recessed grooves on the outer surface of the screen so that the rotor blades can be closer to the screen, thereby making the screen have better debonding effect and higher working efficiency.
[0016] Obviously, the grooves have a bottom and are not through-grooves. Raised ribs are arranged where there are no screen holes or screen slots, but grooves can be arranged in areas with screen holes to provide more open area and thus increase production.
[0017] According to a preferred embodiment of the present invention, the groove width gradually increases from the top (slurry inlet end) to the bottom (slag discharge end) of the screen. Due to the "sweep effect", the amount of impurities accumulated on the leading edge of the rotor blade will gradually increase from the top to the bottom of the screen. The gradual increase in the groove width from the top to the bottom of the screen is adapted to the gradual increase in the amount of accumulated impurities.
[0018] According to a preferred embodiment of the present invention, the groove depth gradually increases from the top (slurry inlet end) to the bottom (slag discharge end) of the screen. Due to the "sweep effect", the amount of impurities accumulated on the leading edge of the rotor blade gradually increases from the top to the bottom of the screen. The gradual increase in the groove depth from the top to the bottom of the screen is adapted to the gradual increase in the amount of accumulated impurities.
[0019] According to a preferred embodiment of the present invention, the groove width and depth gradually increase from the top (slurry inlet end) to the bottom (slag discharge end) of the screen. Due to the "sweep effect", the amount of impurities accumulated on the leading edge of the rotor blades gradually increases from the top to the bottom of the screen. The gradual increase in the groove width and depth from the top to the bottom of the screen is consistent with the gradual increase in the amount of accumulated impurities.
[0020] Similarly, the recessed grooves on the outer surface of the screen of the pulp screen are arranged at an angle to the front edge of the blade of the rotor. It is further preferred that the grooves are arranged at an angle greater than 90 degrees to the front edge of the blade. Of course, it is also possible to consider arranging the grooves perpendicular to the blades or at other angles.
[0021] Preferably, on the outer surface of the screen of the pulp screen, the grooves and the leading edges of the blades of the rotor have substantially the same extension range at the height of the screen, thereby improving the deflaking effect over the entire height of the screen.
[0022] Each groove can be designed as a single groove spanning the height of the screen. However, it is preferred that a plurality of groups of grooves arranged on the outer surface of the screen of the screen cover the height of the screen.
[0023] The screen is a hole screen or a slot screen. For the screen designed as a slot screen, the screen slot is preferably arranged at an angle to the front edge of the rotor blade. The screen slot is arranged at a certain angle to the rotation axis, which improves the transportation capacity of the slurry and impurities from the feed inlet to the slurry outlet and keeps the screen basket clean.
[0024] The beneficial effects of the pulp screen of the present invention are: firstly, the ratio of the provided screen area to the size of the pulp screen is greatly improved compared with a flat screen plate, and the size of the pulp screen is smaller under the condition of the same capacity; secondly, since the screen area is more fully utilized and the blade tip speed is reduced, the power consumption is reduced; and, due to the reduced blade tip speed and the application of the in-flow principle, the screen wear caused by centrifugal force is greatly reduced, and heavy impurities can be removed from the outside of the screen instead of being left inside the screen; in addition, since the rotor is arranged on the outside of the screen basket, the rotor or the rotor blades can be easily replaced. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1A schematic cross-sectional view of a pulp screening machine according to an embodiment of the present invention is shown, wherein only the screen and the rotor are shown;
[0026] Figure 2 A schematic cross-sectional view of a pulp screening machine according to another embodiment of the present invention is shown, wherein only the screen and the rotor are shown;
[0027] Figure 3 A schematic cross-sectional view of a pulp screening machine according to another embodiment of the present invention is shown, wherein only the screen and the rotor are shown;
[0028] Figure 4 A schematic perspective view shows a rotor and a screen of a pulp screening machine according to the present invention;
[0029] Figure 5 A perspective view schematically shows the raised ribs on the outer side of the screen of the pulp screening machine according to the present invention;
[0030] Figure 6 Schematically showing a screen and a rotor of a pulp screen according to the present invention;
[0031] Figure 7 The rotor corresponding to the basket screen in the prior art is schematically shown;
[0032] Figure 8 Schematically shows Figure 7 A partial cross-sectional view of the rotor blades and basket screen of the rotor shown. DETAILED DESCRIPTION
[0033] Figure 1 The cross-sectional view of a pulp screening machine according to an embodiment of the present invention is schematically shown, wherein only the screen mesh and the rotor of the screen basket type are shown. As shown in the figure, the screen mesh 200 of the pulp screening machine is in the shape of a cone that gradually narrows upward, and the rotor 100 rotates around the outside of the screen mesh 200, wherein the pulp outlet (not shown) of the pulp screening machine is arranged inside the screen mesh 200, and the pulp inlet (not shown) and the pulp residue outlet (not shown) are arranged outside the screen mesh 200.
[0034] Figure 2 A cross-sectional view of a pulp screening machine according to another embodiment of the present invention is schematically shown, wherein only the screen and the rotor are shown. As shown in the figure, the screen 200 of the pulp screening machine is in the shape of a cylinder protruding vertically upward, and the rotor 100 rotates around the outer side of the screen 200.
[0035] Figure 3 A cross-sectional view of a pulp screening machine according to another embodiment of the present invention is schematically shown, wherein only the screen and the rotor are shown. As shown in the figure, the screen 200 of the pulp screening machine is in the shape of a cone that gradually widens upwards, and the rotor 100 rotates around the outer side of the screen 200.
[0036] The screen angle α is Figures 1 to 3 The angle between the screen shown and the horizontal plane is between 45° and 135°, preferably between 75° and 105°, depending on the pulp preparation used and the application scenario. The inventors have noticed that when the angle α is less than 90°, the debonding ability is enhanced, while when it is greater than 90°, the quality of the good pulp can be improved.
[0037] Under similar deflaking effects, the rotor blade tip speed of the pulp screen of the present invention is reduced by up to 30% compared with the disc pulp screen in the prior art, which will significantly reduce energy consumption and extend the service life of the screen basket and the rotor.
[0038] Figure 4 The rotor and screen of the pulp screening machine according to the present invention are schematically shown in a stereoscopic diagram. The rotor 100 is surrounded by the outer side of the screen 200 as shown in the figure. The outer side of the screen 200 is provided with raised ribs 210. The ribs 210 are used to improve the debonding capacity and prevent waste (impurities) from accumulating between the rotor and the screen. In different embodiments, it is also possible to consider replacing the ribs with grooves to achieve similar technical effects. Figure 5 Another screen of a pulp screening machine according to the present invention is schematically shown in a three-dimensional diagram, wherein a recessed groove 220 is provided on the outer side of the screen 200 .
[0039] Depending on the pulp preparation and application scenario, a sieve-type screen basket can also be used, which can improve the quality of the good pulp while maintaining high decomposition efficiency. The sieve slits 230 are arranged at a certain angle to the rotating shaft, which improves the transportation capacity of the pulp and impurities from the feed inlet to the pulp residue outlet and keeps the screen basket clean. Figure 6 The screen and rotor of the pulp screen according to the present invention are schematically shown. The screen is a slotted screen, and the figure shows a screen slot 230 on the outer surface of the screen. The screen slot 230 is arranged at an angle to the blade front 110 of the rotor.
[0040] The preferred embodiments of the present invention are disclosed above, but the purpose and scope of the present invention are not limited to the specific contents disclosed. Those skilled in the art can develop more embodiments and specific applications through the teachings of the present invention, and these embodiments and specific applications also belong to the purpose and scope of the present invention. Therefore, it is understood that the specific embodiments of the present invention do not further limit the purpose and scope of the invention defined in the claims.
[0041] Reference numerals list
[0042] 100 Rotors
[0043] 101 Rotor Blades
[0044] 102 rotor base
[0045] 103 Ring member
[0046] 110 Leading edge of rotor blades
[0047] 200 Screen
[0048] 210 Raised Ribs
[0049] 220 Concave Groove
[0050] 230 Sieve slots.
Claims
1. A pulp screening machine, characterized in that: The pulp screening machine comprises: a screen (200) protruding upward from the bottom of the pulp screening machine and a rotor (100) rotating around the outside of the screen, wherein the pulp outlet of the pulp screening machine is arranged on the inside of the screen (200), and the pulp inlet and pulp residue outlet are arranged on the outside of the screen (200), wherein the rotor blades (101) of the rotor (100) extend from a rotor base (102) located on the top of the screen (200) to the area of the screen (200) in a cantilevered manner, and the rotor blades (101) are arranged on the inside of the screen (200). The screen (200) is not connected to each other in the area, wherein the rotor blades (101) have a rigidity suitable for achieving a debonding effect together with the outer surface of the screen (200), wherein the outer surface of the screen (200) has raised ribs (210) or recessed grooves (220), wherein the raised ribs (210) or recessed grooves (220) on the outer surface of the screen (200) are arranged at an angle to the blade front edge (110) of the rotor.
2. The pulp screen according to claim 1, characterized in that: The screen (200) of the pulp screening machine is in the shape of a cylinder protruding vertically upward.
3. The pulp screen according to claim 1, characterized in that: The screen (200) of the pulp screening machine is in the shape of a cone that gradually widens upwards.
4. The pulp screen according to claim 1, characterized in that: The screen (200) of the pulp screening machine is in the shape of a cone that gradually narrows upwards.
5. The pulp screen according to any one of claims 1 to 4, characterized in that: On the outer surface of the screen (200) of the screen, the ribs (210) or the grooves (220) have the same extension as the blade leading edge (110) of the rotor at the height of the screen.
6. The pulp screen according to any one of claims 1 to 4, characterized in that: The height of the screen (200) is covered by a plurality of groups of ribs (210) or grooves (220) arranged on the outer surface of the screen (200) of the pulp screening machine.
7. The pulp screen according to any one of claims 1 to 4, characterized in that: The width of the ribs (210) or the grooves (220) gradually increases from the top to the bottom of the screen (200).
8. The pulp screen according to any one of claims 1 to 4, characterized in that: The depth of the ribs (210) or the grooves (220) gradually increases from the top to the bottom of the screen (200).
9. The pulp screen according to any one of claims 1 to 4, characterized in that: The sieve (200) is a porous sieve.
10. The pulp screen according to any one of claims 1 to 4, characterized in that: The screen (200) is a slotted screen.
11. The pulp screen according to claim 10, characterized in that: The screen slots of the screen (200) are arranged at an angle to the leading edge (110) of the blades of the rotor.
12. The pulp screen according to claim 10, characterized in that: The screen slots of the screen (200) are arranged at an angle to the rotation axis of the rotor.
13. The pulp screen according to any one of claims 1 to 4, characterized in that: The housing of the pulp screen is provided with a waste collector arranged along a tangent line for capturing heavy impurities.