Bamboo pulp grading screening system

Abstract

The embodiment of the utility model provides a bamboo pulp grading screening system which comprises at least two screening units connected in parallel, each screening unit comprises at least two pressure screens connected in series, each pressure screen comprises a screen plate used for separating pulp into long fiber pulp and white water, each screen plate comprises screen holes, the diameter of each screen hole is 0.6-1.1 mm, and the diameter of each screen hole is 0.6-1.1 mm. In the same screening unit, the ratio of the area of the screen plate of the pressurized screen located on the upstream to the area of the screen plate of the pressurized screen located on the downstream is 1: (0.55-0.8), the average length of obtained long fiber pulp is better than that in the prior art through the bamboo pulp grading screening system formed through the arrangement, meanwhile, the screening rate of medium and short fibers is greatly increased, and the system runs stably.

Description

Technical Field

[0001] The utility model relates to a bamboo pulp grading and screening system. Background Art

[0002] Due to the large number of miscellaneous cells and fine fibers in bamboo pulp, during the utilization of bamboo pulp, it is usually necessary to perform grading and screening treatment on the bamboo pulp to obtain suitable fibers, such as the processes mentioned in documents such as CN117966505A, CN114855496A, CN116411470A, CN114481666A, etc.

[0003] During the screening process, the usual solution is to first use a smaller screen hole to screen out fine fibers and miscellaneous cells, and then use a sieve plate with a larger screen hole to obtain a pulp with longer average fibers. However, it is found in practice that using this screening and grading scheme, the production of the entire system is not stable during the treatment of bamboo pulp. More specifically, during production, the sieve plate is blocked or needs to be cleaned more frequently during the primary screening and secondary screening processes, and at the same time, the time for blocking or cleaning cannot be fixed or form a pattern.

[0004] Therefore, it is necessary to develop a bamboo pulp grading and screening system to solve the above technical problems. Summary of the Utility Model

[0005] To this end, the utility model provides a bamboo pulp grading and screening system to solve the above technical problems.

[0006] A bamboo pulp grading and screening system includes at least two parallel screening units. Each screening unit includes at least two serially connected pressure screens. The pressure screen includes a sieve plate for separating the pulp into long fiber pulp and white water. The sieve plate includes sieve holes, wherein the aperture of the sieve holes is 0.6 - 1.1 mm, and in the same screening unit, the ratio of the sieve plate area of the pressure screen located upstream to the sieve plate area of the pressure screen located downstream is 1: 0.55 - 0.8.

[0007] Wherein, in the same screening unit, an intermediate pulp tank is arranged between adjacent pressure screens.

[0008] Wherein, the screening unit includes two pressure screens, namely a first pressure screen located upstream and a second pressure screen located downstream, and the ratio of the sieve plate area of the first pressure screen to the sieve plate area of the second pressure screen is 1:0.6 - 0.7.

[0009] Wherein, the opening rate of the sieve plate of the first pressure screen is the same as the opening rate of the sieve plate of the second pressure screen.

[0010] Among them, the first pressure screen includes a volume space surrounded by a housing. The screen plate divides the volume space into a main accommodation area and a filtering area. The first pressure screen further includes a pulp inlet, and the pulp inlet is communicated with the main accommodation area. The first pressure screen includes a white water outlet, and the white water outlet is communicated with the filtering area. A long fiber pulp outlet is further arranged on the lower side of the housing.

[0011] Among them, the screen plate is a frustum with a smaller upper part and a larger lower part, and the screen plate has a taper of 1° to 3°.

[0012] Among them, the first pressure screen further includes a dilution water pipe. The dilution water pipe extends from outside the housing towards the main accommodation area, and the dilution water pipe is arranged at the bottom of the housing.

[0013] Among them, a stirring device is further arranged in the main accommodation area. The stirring device includes a main shaft and a plurality of stirring paddles arranged on the main shaft. The stirring device further includes an isolation cover. The isolation cover includes an inner space formed by surrounding side walls, and the dilution water outlet is located in the inner space.

[0014] Among them, the side walls are fixedly connected to the stirring paddles.

[0015] Among them, the dilution water outlet is arranged adjacent to the main shaft.

[0016] Beneficial effects: The embodiment of the present utility model provides a bamboo pulp grading and screening system, which includes at least two parallel screening units. Each screening unit includes at least two series-connected pressure screens. The pressure screen includes a screen plate for separating the pulp into long fiber pulp and white water. The screen plate includes screen holes, and the aperture of the screen holes is 0.6 to 1.1 mm. Moreover, in the same screening unit, the ratio of the screen plate area of the pressure screen located upstream to the screen plate area of the pressure screen located downstream is 1:0.55 to 0.8. Through the above settings, the formed bamboo pulp grading and screening system has a better average length of the obtained long fiber pulp than the prior art, and at the same time, the removal rate of medium and short fibers is greatly improved, and the system operates stably. Description of the Drawings

[0017] Figure 1 Schematic diagram of the bamboo pulp grading and screening system of the present utility model;

[0018] Figure 2 For Figure 1 Schematic diagram of the structure of the first pressure screen in;

[0019] The first screening unit 10; the first pressure screen 11; the volume space 110; the housing 1100; the filtrate area 1101; the main accommodation area 1102; the sieve plate 111; the main shaft 112; the stirring paddle 113; the stock inlet 114; the white water outlet 115; the dilution water pipe 116; the dilution water outlet 1161; the long fiber pulp outlet 117; the isolation cover 118; the second pressure screen 12; the intermediate pulp tank 13; the second screening unit 20. Detailed implementation mode

[0020] An embodiment of the present utility model provides a bamboo pulp grading and screening system for screening bamboo pulp to obtain long fiber pulp with a suitable fiber length. The present application will be further described below with reference to the accompanying drawings.

[0021] Please refer to Figure 1 , the bamboo pulp grading and screening system includes at least two parallel screening units, and each screening unit includes at least two series-connected pressure screens.

[0022] It can be understood that the bamboo pulp grading and screening system further includes pipes for forming parallel screening units and connecting the pressure screens, and valves provided on the pipes. In this embodiment, the bamboo pulp grading and screening system includes two screening units. For the convenience of description, these two screening units are respectively referred to as the first screening unit 10 and the second screening unit 20. It can be understood that in other embodiments, more screening units can be provided. However, it has been found through practice that when the number of parallel screening units is less than 5, the system operation stability will be better.

[0023] Meanwhile, in this embodiment, each of the first screening unit 10 and the second screening unit 20 includes two series-connected pressure screens. Specifically, the first screening unit 10 includes the first pressure screen 11 and the second pressure screen 12. In other embodiments, three or four pressure screens can also be series-connected in a screening unit. However, it has been found through practice that the number of series-connected pressure screens should be less than 5 to reduce the blockage phenomenon of the pressure screen at the end, thereby ensuring the stability of the system operation.

[0024] Furthermore, an intermediate pulp tank 13 is provided between the first pressure screen and the second pressure screen for adjusting the long fiber pulp concentration of the first pressure screen to reach the required concentration of the screening machine. It can be understood that when more pressure screens are provided in the screening unit, intermediate pulp tanks are provided between adjacent pressure screens.

[0025] Please refer to Figure 2 , in Figure 2 , the structural diagram of the first pressure screen 11 in the first screening unit 10 is shown. It can be understood that the structures of the second pressure screen 12 and the pressure screens in the second screening unit 20 are basically the same as that of the first pressure screen 11, and will not be elaborated here.

[0026] The described first pressure screen 11 includes a volume space 110 enclosed by a housing 1100. In this embodiment, the housing 1100 is in the shape of a cylindrical tube. Inside the volume space 110, a sieve plate 111 is provided. The sieve plate 111 divides the volume space 110 into a main accommodation area 1102 and a filtrate area 1101. Among them, the main accommodation area 1102 is located inside the sieve plate 111, and the filtrate area 1101 is located outside the sieve plate 111. Herein, the "inside" refers to the direction towards the center of the volume space 110, and the "outside" refers to the direction towards the housing 1100.

[0027] The sieve plate 111 includes a number of sieve holes. The aperture of the sieve holes is 0.6 - 1.1 mm. It can be understood that the sieve holes can be circular through-holes, and the sieve holes are arranged in an array on the sieve plate 111.

[0028] Furthermore, the opening ratio of the sieve plate 111 is 20% - 60%. The opening ratio refers to the ratio of the area of the sieve holes on the sieve plate 111 to the area of the sieve plate 111.

[0029] The first pressure screen 11 further includes a pulp inlet 114. The pulp inlet 114 is communicated with the main accommodation area 1102 and is used to convey pulp into the main accommodation area 1102 through the pulp inlet 114. In this embodiment, the pulp is bamboo pulp. Specifically, the bamboo pulp can be a fiber raw material made from bamboo materials such as Phyllostachys heterocycla, Bambusa intermedia, Neosinocalamus affinis, Bambusa pervariabilis × Dendrocalamopsis grandis, Dendrocalamus farinosus, etc. through pulping methods such as the sulfate method or the caustic soda method. At the same time, the bamboo pulp can be natural bamboo pulp or bleached bamboo pulp. The average fiber length of the bamboo pulp can be 0.5 - 5 mm, and the concentration of the pulp is 0.5 - 1.3%.

[0030] The first pressure screen 11 includes a white water outlet 115. The white water outlet 115 is communicated with the filtrate area 1101 and is used to discharge the white water containing a large amount of short fibers after the long fibers are filtered out by the sieve plate 111.

[0031] It can be understood that a long fiber pulp outlet 117 is further provided on the lower side of the housing 1100 for discharging the long fiber pulp containing a large amount of long fibers after the short fibers are filtered out.

[0032] A stirring device is further provided in the main accommodation area 1102 to make the pulp located in the main accommodation area 1102 move along with the stirring device and make the pulp pass through the sieve plate 111 during the movement. It can be understood that when the pulp passes through the sieve plate 111, due to the interception effect of the sieve holes, the long fibers remain in the main accommodation area 1102, while the short fibers can pass through the sieve holes and flow out along with the white water.

[0033] In this embodiment, the stirring device includes a main shaft 112 and a plurality of stirring paddles 113 arranged on the main shaft 112. One end of the stirring paddle 113 is fixed to the main shaft 112, and the other end extends outward from the main shaft 112. When the slurry moves from top to bottom, the stirring paddle 113 drives the slurry to move within the volume space 110.

[0034] Further, the stirring paddle 113 includes a blade, and the blade is inclined.

[0035] Further, the sieve plate 111 is in the shape of a frustum of a cone with a smaller top and a larger bottom, and the sieve plate 111 has a taper of 1° to 3°.

[0036] Further, the first pressure screen 11 further includes a dilution water pipe 116. The dilution water pipe 116 extends from outside the housing 1100 towards the main accommodation area 1102 to input dilution water into the main accommodation area 1102. In this embodiment, the dilution water pipe 116 is arranged at the bottom of the housing 1100.

[0037] Further, the dilution water pipe 116 includes a dilution water outlet 1161, and the dilution water outlet 1161 is arranged adjacent to the main shaft 112.

[0038] Further, the stirring device further includes an isolation cover 118. The isolation cover 118 includes an inner space formed by enclosing side walls. The dilution water outlet 1161 is located within the inner space. The side walls are located between the blade and the main shaft 112, and the side walls are fixedly connected to the stirring paddle 113, such that when the stirring paddle 113 moves, the isolation cover 118 moves along with it. At the same time, a plurality of through holes are provided on the side walls, such that the inner space communicates with the space outside the isolation cover 118.

[0039] In addition, when screening the slurry, the pressure difference between the feed inlet 114 and the long fiber pulp outlet 117 is -15 to -30 kPa.

[0040] In addition, in the same screening unit, the ratio of the area of the sieve plate 111 of the pressure screen located upstream to the area of the sieve plate 111 of the pressure screen located downstream is 1: 0.55 to 0.8. Specifically, in this embodiment, the ratio of the area of the sieve plate 111 of the first pressure screen 11 to the area of the sieve plate 111 of the second pressure screen 12 is 1:0.55 to 0.8. More preferably, it is 1:0.6 to 0.7. In addition, it can be understood that the opening ratio of the sieve plate 111 of the first pressure screen 11 is basically the same as the opening ratio of the sieve plate 111 of the second pressure screen 12.

[0041] Further, the long fiber discharge volume ratio of the upstream pressure screen among adjacent pressure screens is 30% to 60%, preferably 35% to 50%, more preferably 40% to 45%. The long fiber discharge volume ratio of the downstream pressure screen is 40% to 60%, preferably 40% to 50%, more preferably 45% to 50%. The long fiber discharge volume ratio = long fiber discharge volume / pulp inlet volume. The bamboo pulp grading and screening system of the present invention will be described below with reference to specific embodiments.

[0042]

[0043] From the results of the above embodiments and comparative examples, through the bamboo pulp grading and screening system of the present invention, the average length of the long fiber pulp obtained is better than that of the prior art. At the same time, the screening rate of medium and short fibers is greatly improved, and the system operates stably. The above is only the implementation mode of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A bamboo pulp grading and screening system, characterized in that, It includes at least two parallel screening units, and each screening unit includes at least two pressure screens connected in series. The pressure screen includes a sieve plate for separating the pulp into long fiber pulp and white water. The sieve plate includes sieve holes, wherein the aperture of the sieve holes is 0.6 - 1.1 mm, and in the same screening unit, the ratio of the sieve plate area of the pressure screen located upstream to the sieve plate area of the pressure screen located downstream is 1: 0.55 - 0.

8.

2. The bamboo pulp grading and screening system according to claim 1, characterized in that, In the same screening unit, an intermediate pulp tank is arranged between adjacent pressure screens.

3. The bamboo pulp classification and screening system according to claim 2, characterized in that, The screening unit includes two pressure screens, namely the first pressure screen located upstream and the second pressure screen located downstream, and the ratio of the sieve plate area of the first pressure screen to the sieve plate area of the second pressure screen is 1:0.6 - 0.

7.

4. The bamboo pulp grading and screening system according to claim 3, characterized in that The opening ratio of the sieve plate of the first pressure screen is the same as that of the sieve plate of the second pressure screen.

5. The bamboo pulp grading and screening system according to claim 3, characterized in that, The first pressure screen includes a volume space surrounded by a housing. The sieve plate divides the volume space into a main accommodation area and a filtered area. The first pressure screen further includes a pulp inlet, and the pulp inlet is communicated with the main accommodation area. The first pressure screen includes a white water outlet, and the white water outlet is communicated with the filtered area. A long fiber pulp outlet is also arranged on the lower side of the housing.

6. The bamboo pulp grading and screening system according to claim 5, wherein, The sieve plate is in the shape of a frustum of a cone with a smaller top and a larger bottom, and the sieve plate has a taper of 1° - 3°.

7. The bamboo pulp grading and screening system according to claim 5, wherein, The first pressure screen further includes a dilution water pipe, and the dilution water pipe extends from outside the housing towards the main accommodation area, and the dilution water pipe is arranged at the bottom of the housing.

8. The bamboo pulp grading and screening system according to claim 7, wherein, A stirring device is also arranged in the main accommodation area. The stirring device includes a main shaft and a plurality of stirring blades arranged on the main shaft. The stirring device further includes a shielding cover. The shielding cover includes an inner space formed by surrounding side walls, and the dilution water outlet is located in the inner space.

9. The bamboo pulp grading and screening system according to claim 8, wherein, The side walls are fixedly connected with the stirring blades.

10. The bamboo pulp grading and screening system according to claim 8, wherein, The dilution water outlet is arranged adjacent to the main shaft.

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