Pumping sieve and pumping screening system

Abstract

The present invention relates to a pumping sieve, which comprises: a pump housing; a rotor impeller received within the pump housing; a drive shaft that rotatably drives the rotor impeller through the pump housing; wherein the pump inlet of the pump housing faces the front of the rotor impeller, and the pump outlet is located on the outer peripheral side of the pump housing. The pumping sieve further comprises a pulp sieve that divides the pump housing into a centrifugal chamber and a screening chamber. The centrifugal chamber houses the rotor impeller, and the screening chamber has a good pulp outlet. The present invention also provides a pumping and screening system.

Description

Technical Field

[0001] The present invention relates to a pumping screen, which is particularly used in the pulp and paper industry. The present invention also provides a screening system with a pumping screen Background Art

[0002] The pressure screen is the main equipment in the pulp making process of the paper industry

[0003] In the current paper production line, the pressure screen selected for pulp screening usually requires an inlet pressure higher than 1 - 3 kg / cm 2 to ensure the normal and effective operation of the pressure screen under pressure. Because the pulp fluid with a certain pressure makes the screening area between the screen plate and the rotor have the required pressure, and at the same time, the inlet pressure also ensures that the liquid in the pressure screen is in a full state

[0004] There is a small gap between the rotor blades of the pressure screen and the screen drum to ensure that the rotor blades do not contact the screen plate. At the same time, the fluid disturbance generated by the movement of the blades relative to the screen plate acts on the screen plate, and usually the gap is adjustable. During the rotation of the pressure screen rotor, pressure pulses are generated on the pulp through the movement of the rotor blades along the surface of the screen drum, increasing the pressure difference inside and outside the screen plate, thus accelerating the pulp to pass through the screen plate; as the gap between the blade tail and the screen drum gradually increases, the pressure of the blade on the pulp decreases, and a local low-pressure area appears in this area. When the absolute values of the pulp pressures inside and outside the screen plate are equal due to the low-pressure area, the pulp stops screening. When the negative pressure continues to increase, the moisture in the good pulp outside the screen plate and part of the pulp pass through the screen plate and return, playing a role in backwashing the pulp mass and long fiber impurities on the screen plate, thereby ensuring the continuous and normal operation of the pressure screen

[0005] Almost all the pressures required for the operation of various pressure screens come from the centrifugal pump configured in front of the screen in the system. It can even be considered that the screening process of the pressure screen is jointly completed by the pulp screening machine and the centrifugal pump

[0006] Since both the pressure screen and the centrifugal pump have rotors, the normal and effective operation of the pressure screen requires the pressure to be not lower than a certain pressure range, usually in a relatively wide range around 2 kg / cm 2 Under normal circumstances, the linear speed of the rotor of the centrifugal pump that provides pressure for the pressure screen is close to the linear speed of the pressure screen rotor

[0007] In a centrifugal pump, the liquid fills the pump casing, and the impeller rotates at a high speed in the pump casing to generate centrifugal force. The liquid is thrown towards the outer periphery of the impeller at a high speed under the action of centrifugal force. During the process of the liquid flowing from the impeller inlet to the outlet, it passes through the gradually expanding pump casing channel, the speed decreases, and the pressure increases, and the dynamic head is converted into static head

[0008] In the prior art, the centrifugal pump and the pressure screen are two independent process equipment connected by pipelines Summary of the Invention

[0009] The present invention provides a pumping screen, which integrates the pressurization function of a centrifugal pump into the pressure screen itself, thereby achieving pressure screening without using a separate pump, simplifying the process, saving investment costs such as equipment / pipelines / valves and plant space, and reducing power consumption.

[0010] The pumping screen of the present invention includes: a pump casing; a rotor impeller, which is accommodated in the pump casing; a drive shaft, which rotatably drives the rotor impeller through the pump casing; wherein, the pump inlet of the pump casing is opposite to the front of the rotor impeller, and the pump outlet is located on the outer peripheral side of the pump casing; the pumping screen further includes a pulp screen, which divides the pump casing into a centrifugal chamber and a screening chamber, the centrifugal chamber accommodates the rotor impeller, and the screening chamber has a good pulp outlet.

[0011] In the pumping screen provided by the present invention, the two rotors of the centrifugal pump and the pressure screen are integrated on one rotor, so that the device has both the ability to pump and increase pressure, and also has a screening function.

[0012] In the pumping screen provided by the present invention, the pumping pressurization function of the centrifugal pump and the screening function of the pressure screen are integrated together. Only need to arrange the pumping screen of the present invention beside storage equipment such as tanks, and ensure that the lowest liquid level in the tank is higher than the position of the inlet of the pumping screen. After starting, the pumping screen will provide the required screening pressure for its own operation.

[0013] According to a preferred embodiment of the pumping screen of the present invention, the pulp screen is a screen plate fixed on the pump casing or integrally formed on the pump casing on the back side of the rotor impeller. The screen holes of the screen plate are only provided in the radial outer region of the pulp screen, and no screen holes are provided in the central region of the pulp screen.

[0014] The screen plate can be flat, or in the shape of a funnel with the center indented into the screening chamber, or in the shape of a cone with the center protruding towards the centrifugal chamber.

[0015] According to another preferred embodiment of the pumping screen of the present invention, the pulp screen is a hollow structure fixed on or integrally formed on the pump casing on the back side of the rotor impeller. At least a part of the outer peripheral side wall of the hollow structure is a screen plate; the rotor impeller has a bend around the hollow structure in the radial outer periphery, and the bend divides the rotor impeller into a centrifugal impeller part close to the drive shaft and a screening impeller part close to the distal end. The back side of the screening impeller part of the rotor impeller is opposite to the screen plate.

[0016] Wherein, the rotor impeller can bend towards the back side of the rotor impeller in the radial outer periphery, or the rotor impeller can also bend towards the front side of the rotor impeller in the radial outer periphery.

[0017] Preferably, the hollow structure is frustum-shaped, with the top surface of the frustum facing the back side of the rotor impeller, and the outer peripheral side wall of the frustum forming the sieve plate.

[0018] Preferably, the hollow structure is cylindrical, with the top surface of the cylinder facing the back side of the rotor impeller, and the outer peripheral side wall of the cylinder forming the sieve plate.

[0019] The outer peripheral side wall of the hollow structure can be arc-shaped.

[0020] The pumping sieve provided by the present invention has the same installation position as a common centrifugal slurry pump, which is arranged beside a slurry pond or a water pool to ensure that the inlet height is below the liquid level of the slurry pond or the water pool; similar to a common centrifugal pump, the center line of the inlet pipe of the pumping sieve of the present invention and the center line of the rotor are designed to be coaxially connected. The slurry flows into the housing of the pumping sieve by means of the static pressure of the liquid level in the slurry pond or the white water pond before the pump and the suction force generated by the "pumping sieve" rotor (the eddy low pressure effect at the center of the impeller), reaches the pumping area, is accelerated to a certain linear velocity (usually in the range of 10 - 30 m / s according to the pressure requirement) by the pumping blades, and then reaches the screening area. In the screening area, the slurry has a pressure of 1 - 3 kg / cm 2 of pressure.

[0021] When the slurry enters the pumping sieve of the present invention, it first contacts the part of the rotor with a centrifugal acceleration function. The slurry is accelerated to a certain linear velocity by the blades of the rotor, so that the slurry fluid has sufficient dynamic pressure head. Then, the slurry with pressure reaches the screening area composed of sieve holes (or sieve slots) and the rotor blades. In this screening area, there are no longer centrifugal acceleration blades, so similar to the principle of a centrifugal pump, the velocity of the fluid is converted into pressure, and pressure screening is carried out in this area.

[0022] In the screening area, the slurry passing through the sieve holes or sieve slots enters the good pulp chamber. Although there is a certain pressure drop (usually only 0.1 - 0.5 kg / cm 2 ) after the slurry passes through the sieve plate, it still has sufficient pressure. The good pulp is transported to the next process by this pressure, and can even reach the thickener with the highest installation position in the workshop. The tailings slurry that does not pass through the sieve plate is also discharged from the equipment under the action of the pressure in the screening area, and is sent to the next process or discharged from the system.

[0023] In this way, it is realized that the pressure required in the screening area of the pumping sieve is provided by its own rotor, and at the same time, the tailings with pressure after screening can be discharged to other processes.

[0024] Compared with the pressure screen in the prior art, the pumping sieve provided by the present invention has simple installation requirements, small floor area, saves the investment cost of equipment and pipelines, reduces the pressure loss during the pumping process, and also reduces the power consumption.

[0025] One of the most advantageous applications of the pumping screen of the present invention is to install the pumping screen between the pulper and the hydraulic cleaner in the low-consistency pulping system of the waste paper pulping and papermaking industry, which can improve the pulping ability of the pulper and the slag discharging ability of the hydraulic cleaner at the same time.

[0026] Another advantage of using the pumping screen of the present invention is that the pressured tail slag of the pumping screen can ensure that the good pulp of the hydraulic cleaner has sufficient pressure, thus avoiding the low concentration of the hydraulic cleaner or the return of the intermittently discharged good pulp to the discharge pump of the pulper, and also avoiding the periodic low-concentration valley value discharge of the discharge pump. Finally, the continuous stability of the good pulp concentration and flow is achieved, and the discharge pump can work continuously and stably.

[0027] After using the pumping screen of the present invention, the good pulp and slag of the "pumping screen" can be continuously discharged. The pulp mixture from the pulper tank is first processed by the pumping screen of the present invention and then sent to the cleaner. The already disintegrated fibers in the pulp are continuously separated by the pumping screen of the present invention, so that the part that should not originally enter the hydraulic cleaner (the already disintegrated fibers) is continuously discharged by the discharge pump as part of the output of the pulper, thus having an additional output of good pulp. The fiber ratio of the mixed material entering the hydraulic cleaner is reduced, and the total amount is correspondingly reduced, and the capacity of the hydraulic cleaner is correspondingly improved. In this way, the functions of both the hydraulic pulper and the hydraulic cleaner are improved by increasing the separation of fibers from paper sheets and fragments once.

[0028] The pumping screen provided by the present invention only requires a pressure increase of 2 to 5 meters at the slag discharge relative to the inlet pressure. In addition, since the good pulp is continuously discharged to the discharge pump installed at a lower position, the good pulp does not need to carry pressure, and the specific implementation is relatively simple.

[0029] The present invention also provides a screening system, which includes a pulp tank, a pulp and slag tank and a good pulp tank, and also includes the above-mentioned pumping screen. The pump inlet of the pumping screen is directly connected to the pulp tank to draw pulp, the pump outlet is connected to the pulp and slag tank, and the good pulp outlet is connected to the good pulp tank. Description of the Drawings

[0030] Figure 1 Shows the layout of the pump and the separate pressure screen in the prior art;

[0031] Figure 2 Illustrates the layout of the pumping screen of the present invention during the pulp screening process;

[0032] Figures 3A to 3C Illustrates the preferred embodiment of the pumping screen of the present invention, which shows various different forms of sieve plates;

[0033] Figures 4A to 4DSchematically shows a preferred embodiment of the pumping sieve of the present invention, in which pulp sieves of various different hollow structural forms and a bent rotor impeller are shown.

[0034] In the figures, the same or similar technical features have the same reference numerals. Detailed implementation manners

[0035] Figure 1 Shows the arrangement of a single pressure sieve in the prior art, as Figure 1 shown, the pulp pump 102 is arranged at the rear end of the pulp inlet tank 101. The pulp pump 102 sends the pressurized pulp into the pressure sieve 103, and after screening, it is respectively sent into the slag pulp tank 104 and the good pulp tank 105.

[0036] The pulp pump and the pressure sieve are respectively arranged as two independent devices in the pulp screening system. Not only is the installation complex and the floor area large, but also the potential energy generated by the height difference between the two devices causes an increase in energy consumption during actual production.

[0037] Figure 2 Schematically shows the arrangement of the pumping sieve of the present invention during the pulp screening process, as Figure 2 shown. It can be clearly seen that in the pumping sieve 200 provided by the present invention, the centrifugal pump and the pressure sieve are integrated together, so that the device has both the pumping ability and the screening function.

[0038] In the pumping sieve 200 provided by the present invention, the pumping and pressurizing function of the centrifugal pump and the screening function of the pressure sieve are integrated together. Only need to arrange the pumping sieve of the present invention beside the pulp inlet tank 101 or storage devices such as tanks, and ensure that the lowest liquid level in the pulp inlet tank 101 or tank is higher than the position of the inlet of the pumping sieve 200. After starting, the pumping sieve 200 will provide the required screening pressure for its own operation.

[0039] After being screened by the pumping sieve 100, the pulp is respectively sent into the slag pulp tank 104 and the good pulp tank 105.

[0040] Figures 3A to 3C Schematically shows a preferred embodiment of the pumping sieve of the present invention, as Figure 3A shown in FIGS. 3A to 3C. The pumping sieve 200 of the present invention includes: a pump casing 210; a rotor impeller 220, the rotor impeller 220 is accommodated in the pump casing 210; a drive shaft 230, the drive shaft 230 passes through the pump casing 210 and rotationally drives the rotor impeller 220; wherein, the pump inlet 240 of the pump casing 210 is opposite to the front of the rotor impeller 220, and the pump outlet 250 is located on the outer peripheral side of the pump casing 210; the pumping sieve 200 further includes a pulp sieve 260, the pulp sieve 260 divides the pump casing 210 into a centrifugal chamber 270 and a screening chamber 280, the centrifugal chamber 270 accommodates the rotor impeller 220, and the screening chamber 280 has a good pulp outlet 290.

[0041] Among them, the pulp sieve 260 is a sieve plate fixed or integrally formed on the pump housing 210 on the back side of the rotor impeller 220.

[0042] Among them, Figure 3A It is shown that the sieve plate 260 of the pumping sieve 200 is flat; Figure 3B It is shown that the sieve plate 260 of the pumping sieve 200 is in a conical shape protruding from the center to the centrifugal chamber 270, Figure 3C It is shown that the sieve plate 260 of the pumping sieve 200 is in a funnel shape with the center indented into the screening chamber.

[0043] From each view, it can also be seen that in Figure 3A , Figure 3B , Figure 3C , the sieve holes of the sieve plate 260 of the pumping sieve 200 are only provided in the radially outer region of the sieve plate 260, and no sieve holes are provided in the central region of the sieve plate 260.

[0044] Figures 4A to 4D Schematically shows several deformation structures of the pulp sieve and the rotor impeller in the pumping sieve of the present invention. As Figures 4A to 4D shown, the pulp sieve 260 of the pumping sieve 200 is a hollow structure fixed or integrally formed on the pump housing 210 on the back side of the rotor impeller 220. At least a part of the outer peripheral side wall of this hollow structure is the sieve plate; the rotor impeller 220 has a bend around the hollow structure at its radial outer periphery, and the bend divides the rotor impeller into a centrifugal impeller part close to the drive shaft and a screening impeller part close to the distal end. The back side of the screening impeller part of the rotor impeller 220 faces the sieve plate.

[0045] Whether it is Figures 3A to 3C the flat sieve plate in Figures 4A to 4D or the sieve plate arranged as at least a part of the outer peripheral side wall of the hollow structure shown in

[0046] In Figure 4A , Figure 4B , the sieve holes are arranged in the radially outer region. For the flat sieve plate, the sieve holes are arranged in the radially outer region of the sieve plate; for the sieve holes on the outer peripheral side wall of the hollow structure, the sieve holes are arranged on the outer peripheral side wall, so they are also arranged in the radially outer region.

[0047] In Figure 4C and Figure 4D , the hollow structure fixed or integrally formed on the pump housing 210 on the back side of the rotor impeller 220 is cylindrical, the top surface of the cylinder faces the back side of the rotor impeller, and the outer peripheral side wall of the cylinder forms the sieve plate.

[0048] In Figure 4A and Figure 4D the rotor impeller 220 is bent on the back side of the rotor impeller 220 in the radial circumferential direction.

[0049] In Figure 4B and Figure 4C the rotor impeller 220 is bent on the front side of the rotor impeller 220 in the radial circumferential direction.

[0050] In addition, it should be understood that the sieve plate constituting the outer peripheral side wall of the hollow structure of the pulp sieve 260 can also be arc-shaped.

[0051] In addition, it is easy to understand that in the pulp sieve in the form of a hollow structure shown in Figures 4A to 4D while keeping most of the radial inner side area of the cylindrical top surface or frustum top surface of the pulp sieve without sieve holes to realize the pumping function of the pumping sieve described in the present invention, it is also allowed that the outermost radial area of the cylindrical top surface or frustum top surface has sieve holes, although this is not the preferred implementation form. Because, analogous to the planar sieve plate in Figures 3A to 3C it is also completely feasible to arrange sieve holes in the outermost radial area of the cylindrical top surface or frustum top surface.

[0052] In each of the above views, different implementation forms of the pumping sieve 200 are schematically shown. It can be seen that the pumping sieve 200 integrates the pumping and boosting function of a centrifugal pump in the prior art and the screening function of a pressure sieve. It not only has simple installation requirements, small floor area, saves equipment and pipeline investment costs, but also reduces the pressure loss during pumping and the power consumption will also be reduced.

[0053] The above records the preferred embodiments of the present invention, but the spirit and scope of the present invention are not limited to the specific content disclosed here. Those skilled in the art can arbitrarily combine and expand the above embodiments according to the teachings of the present invention and make more implementation forms and applications within the spirit and scope of the present invention. The spirit and scope of the present invention are not limited by specific embodiments, but are defined by the claims.

[0054] Reference numerals

[0055] 101 Feed pulp tank

[0056] 102 Pulp pump

[0057] 103 Pressure sieve

[0058] 104 Slurry tank

[0059] 105 Good pulp tank

[0060] 200 Pumping sieve

[0061] 210 Pump housing

[0062] 220 Rotor impeller

[0063] 230 Drive shaft

[0064] 240 Pump inlet

[0065] 250 Pump outlet

[0066] 260 Pulp sieve, sieve plate

[0067] 270 Centrifugal chamber

[0068] 280 Screening chamber

[0069] 290 Good pulp outlet

Claims

1. A pumping sieve, the pumping sieve comprising: Pump casing; A rotor impeller, which is accommodated in the pump casing; A drive shaft, which rotatably drives the rotor impeller through the pump casing; Wherein, the pump inlet of the pump casing faces the front of the rotor impeller, and the pump outlet is located on the outer peripheral side surface of the pump casing. Characterized in that This pumping sieve further includes a pulp sieve, which divides the pump casing into a centrifugal chamber and a screening chamber. The centrifugal chamber accommodates the rotor impeller, and the screening chamber has a good pulp outlet. Wherein, in the pulp flow direction, the rotor impeller is designed to have a part with a centrifugal acceleration function upstream, and the rotor impeller downstream together with the sieve holes or sieve slits forms a rotor rotor of the screening area without centrifugal acceleration blades. The rotor impeller can accelerate the pulp fluid to a dynamic pressure head sufficient to enable the good pulp and tailing pulp formed after the screening area to reach the next process in the part with the centrifugal acceleration function.

2. The pumping sieve according to claim 1, wherein The pulp sieve is a sieve plate fixed on or integrally formed with the pump casing on the back side of the rotor impeller. The sieve holes of the sieve plate are only arranged in the radial outer area of the pulp sieve, and no sieve holes are arranged in the central area of the pulp sieve.

3. The pumping sieve according to claim 2, wherein The sieve plate is in a planar shape.

4. The pumping sieve according to claim 2, wherein The sieve plate is in a funnel shape with the center indented into the screening chamber.

5. The pumping sieve according to claim 2, wherein The sieve plate is in a conical shape with the center bulging towards the centrifugal chamber.

6. The pumping sieve according to claim 1, wherein The pulp sieve is a hollow structure fixed on or integrally formed with the pump casing on the back side of the rotor impeller. At least a part of the outer peripheral side wall of the hollow structure is a sieve plate. The rotor impeller has a bend around the hollow structure in the radial outer periphery. The bend divides the rotor impeller into a centrifugal impeller part close to the drive shaft and a screening impeller part close to the distal end. The back side of the screening impeller part of the rotor impeller faces the sieve plate.

7. The pumping sieve according to claim 6, wherein The rotor impeller bends towards the back side of the rotor impeller in the radial outer periphery.

8. The pumping sieve according to claim 6, wherein The rotor impeller bends towards the front of the rotor impeller in the radial outer periphery.

9. The pumping sieve according to claim 7 or 8, wherein The hollow structure is in a frustum shape, the top surface of the frustum is opposite to the back side of the rotor impeller, and the outer peripheral side wall of the frustum forms the sieve plate.

10. The pumping sieve according to claim 7 or 8, wherein The hollow structure is in a cylindrical shape, the top surface of the cylinder is opposite to the back side of the rotor impeller, and the outer peripheral side wall of the cylinder forms the sieve plate.

11. The pumping sieve according to claim 7 or 8, wherein The outer peripheral side wall of the hollow structure is arc-shaped.

12. A screening system, comprising a pulp tank, a pulp residue tank and a good pulp tank, wherein This screening system further includes a pumping sieve according to any one of claims 1 to 11. The pump inlet of the pumping sieve is directly connected to the pulp pool to extract pulp, the pump outlet is connected to the pulp residue pool, and the good pulp outlet is connected to the good pulp pool.

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