Special paper pulp beating method

Abstract

The invention relates to a special paper pulp beating method, which adopts graded and sectional type circulating beating, not only can efficiently improve the beating degree of paper pulp to the pulping index requirement of special paper, but also ensures the uniformity of fed and discharged pulp in the beating process through the design of a circulating beating device, effectively avoids the back-mixing phenomenon, ensures the pulping quality, and improves the pulping efficiency. The energy consumption of the pulping process is remarkably reduced, the aims of saving energy and reducing consumption are achieved, and the contradiction problem of high pulping degree and energy consumption control in special paper production is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking, in particular to a special pulp beating method. Background Art

[0002] In the modern papermaking industry, pulping technology plays a vital role in the paper production process. The quality of pulping directly affects the papermaking performance and the quality of the final product. For ordinary paper, the required pulping degree is relatively low, usually 30-40 0 SR (beating degree) is between 85-98. This level of beating is relatively easy to achieve and consumes less energy. However, in the field of specialty paper, especially in the production of specialty paper with extremely high requirements for paper strength, smoothness and uniformity, it is often necessary to reach 85-98. 0 SR's high beating degree.

[0003] There are multiple technical challenges in achieving such a high beating degree: first, traditional methods usually achieve the goal by extending the beating time or increasing the beating intensity, which inevitably leads to a large amount of electricity consumption, which not only increases production costs, but also goes against the current industrial policy of energy conservation and emission reduction. Second, excessive beating may damage the fiber structure of the pulp, thereby affecting the strength and other physical properties of the final paper. These conventional methods often cause other problems while solving one problem, and it is difficult to take into account multiple key factors such as energy consumption control, fiber quality protection and beating uniformity at the same time. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a special pulp beating method which adopts graded and segmented circulating pulping to significantly reduce the energy consumption of the pulping process while ensuring the quality of the pulp.

[0005] In order to achieve the above-mentioned object, the special pulp beating method designed by the present invention comprises a circulating beating device and at least one first-stage refiner and one second-stage refiner, and comprises the following steps:

[0006] S100. Desanding the pulp stock;

[0007] S200. The desanded pulp is transported to a first-stage pulping machine for a first pulping process, wherein the first pulping process includes:

[0008] The raw pulp is circulated and beaten once by an independent circulating pulping device and then transported to a first-stage pulping machine;

[0009] The outlet of the first refiner is divided into a path and transported to the circulating pulping device for secondary circulating pulping;

[0010] S300. The pulp after the primary refining treatment is transported to the second-stage refiner for secondary refining treatment, wherein the secondary refining treatment includes:

[0011] The pulp is circulated and beaten once by an independent circulating pulping device and then transported to the second-stage refiner;

[0012] The outlet of the second-stage refiner is divided into a path and transported to the first circulation beating device for secondary circulation beating;

[0013] S400. The pulp after the secondary refining treatment is transported to the papermaking pool.

[0014] In order to break up the pulp fibers and avoid the back-mixing of the pulp during the beating process, the circulating beating device includes:

[0015] The barrel body is arranged vertically, with a pulp inlet opening at the top and a pulp outlet opening at the bottom;

[0016] The flow guide part is vertically arranged in the barrel body;

[0017] The slurry inlet and outlet are connected to form a slurry channel, and the guide portion is used to guide the slurry in the slurry channel to fall along the circumferential distribution of the barrel body, so that the distribution density difference of the slurry on the cross-section of the barrel body does not exceed a preset threshold.

[0018] In order to improve the uniformity of beating, multiple guide parts are provided in the barrel body through a support frame. The multiple guide parts are arranged equidistantly in the lower pulp channel along the vertical direction. The radial cross-sectional area of ​​the upper and lower ends of each guide part gradually decreases in opposite directions to form a conical structure.

[0019] In order to return part of the pulp to the circulating pulping device to achieve multi-stage pulping and stabilize the pulp inlet pressure of the pulper, it also includes a high-level box arranged at a height higher than the first-stage pulper and the second-stage pulper; the high-level box includes a box body and a pulp inlet, a pulp outlet and a return pipe all arranged on the box body, the pulp inlet is connected to the pulp outlet of the corresponding circulating pulping device through a pipeline, the pulp outlet is connected to the corresponding first-stage pulper or the second-stage pulper through a pipeline, and the return pipe is connected to the pulp inlet of the corresponding circulating pulping device.

[0020] In order to ensure the beating degree and quality consistency of each batch of pulp, in steps S200 and S300, the first-stage refiner and the second-stage refiner both perform the refining process at a constant power.

[0021] In order to avoid over-beating, the pulp beating degree after one refining treatment should reach 55-65 0 SR.

[0022] In order to improve paper quality, increase pulping efficiency and save refining time, the first-stage refiner is a cylindrical refiner and the second-stage refiner is a double-disc refiner, the width of the double-disc refiner teeth is 1.8-2 times the target fiber length for pulping.

[0023] In order to avoid adverse effects of excessively high or low temperatures on the fibers, in steps S200 and S300, the slurry temperature is controlled at 40° C. to 50° C. through the jacket heat exchange structure of the circulating pulping device.

[0024] In order to ensure the purity of the pulp and avoid wear or damage to the pulper, an iron remover is provided in front of the pulp inlet pipe of the circulating pulping device, and the magnetic induction intensity of the iron remover is 10000-12000GS.

[0025] In order to ensure the uniformity of slurry transportation, the circulating beating device and the high-level box, the high-level box and the first-stage refiner, the high-level box and the second-stage refiner, the first-stage refiner and the circulating beating device, and the second-stage refiner and the circulating beating device are all connected through a frequency-controlled slurry supply pump.

[0026] The special pulp beating method designed by the present invention adopts graded and segmented circulating pulping, which can not only efficiently improve the pulp beating degree to the pulping index requirements of special paper, but also ensure the uniformity of the pulp in and out during the pulping process through the design of the circulating pulping device, effectively avoiding the backmixing phenomenon, while ensuring the quality of the pulp, significantly reducing the energy consumption of the pulping process, achieving the goal of energy saving and consumption reduction, and effectively solving the contradiction between high beating degree and energy consumption control in special paper production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a special pulp beating method provided in an embodiment of the present application;

[0028] Figure 2 It is a schematic diagram of the structure of a circulating pulping device provided in an embodiment of the present application;

[0029] Figure 3 It is a flowchart of the beating process provided by the embodiment of the present application;

[0030] Figure 4 This is another pulping process flow chart provided in an embodiment of the present application.

[0031] Among them: a circulating pulping device 10, a barrel body 11, a pulp inlet pipe 111, a pulp outlet pipe 112, a guide part 12, a pulp lowering channel 13, a support frame 14, an exhaust port 15, a liquid level meter 16, a temperature sensor 17, a first-stage refiner 20, a second-stage refiner 30, a high-level box 40, a pulp inlet 41, a pulp outlet 42, a reflux pipe 43, a jacket heat exchange structure 50, a cooling water inlet 51, a cooling water outlet 52, a deironer 60, and a pulp supply pump 70. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0033] Example 1.

[0034] like Figure 1-3 As shown, the special pulp beating method provided in this embodiment is applied to the pulping of special paper. The pulping quality during the pulping process is controllable, the pulp quality is stable, and the demand for high-beating degree pulp can be met.

[0035] Figure 1 The flow chart of a special pulp beating method provided in the embodiment of the present application is as follows. It should be noted that the method is not based on Figure 1 The specific sequence described below is not limited, and it should be understood that in other embodiments, the order of some steps in the method can be interchanged according to actual needs, or some steps can be omitted or deleted. The method includes a circulating pulping device 10 and at least one first-stage refiner 20 and a second-stage refiner 30, such as Figure 3 As shown, the specific steps include:

[0036] S100. Desanding the raw pulp.

[0037] For example, the pulp stock is subjected to a sand removal treatment, and the pulp stock after sand removal is generally 15 0 SR, the purpose of desanding is to remove impurities in the pulp, prevent damage to subsequent pulping equipment, and ensure the smooth progress of the pulping process.

[0038] S200. The desanded pulp is transported to a refiner 20 for a first refining process, wherein the first refining process includes:

[0039] The raw pulp is subjected to one-time circulation beating by an independent circulation beating device 10 and then transported to a first-stage refiner 20; a path is separated from the outlet of the first-stage refiner 20 and transported to the circulation beating device 10 for secondary circulation beating.

[0040] Illustratively, the pulp stock after sand removal first enters the circulating beating device 10, where the pulp is fully dispersed and beaten and then enters a first-stage refiner 20. The first-stage refiner 20 cuts and refines the dispersed pulp to improve the beating degree of the pulp. At the same time, part of the pulp at the outlet end of the first-stage refiner 20 returns to the circulating beating device 10 for secondary circulating beating to ensure the uniformity and sufficiency of the beating.

[0041] In some embodiments, the first refiner 20 is a cylindrical refiner, that is, the first refinement process is a gentle and stable fiber processing process, which can retain the length of the fiber as much as possible and refine the pulp fibers to make the pulp beating degree of the pulp increase from 15 to 20%. 0 SR refining increased to 55-65 0 SR, in addition, through the multiple circulation beating treatments of the circulation beating device 10, the pulp fibers can be dispersed more evenly before the pulping treatment to avoid agglomeration.

[0042] S300. The pulp after the primary refining treatment is transported to the second-stage refiner 30 for secondary refining treatment, wherein the secondary refining treatment includes:

[0043] The pulp is subjected to a one-time circulation beating by an independent circulation beating device 10 and then transported to the second-stage refiner 30;

[0044] A path is separated from the outlet of the second-stage refiner 30 and transported to the first circulation beating device 10 for secondary circulation beating.

[0045] In specific implementation, the pulp after the primary refining treatment is transported to the first-stage post-grinding pulp tank 21, and then transported to the circulating pulping device 10 for circulating pulping. The treated pulp enters the second-stage refiner 30 for fine processing to further improve the pulping degree. Similarly, part of the pulp treated by the second-stage refiner 30 returns to the circulating pulping device 10 for re-slurrying to ensure uniformity and efficiency during the pulping process. Among them, the first-stage post-grinding pulp tank 21 has the pulp storage capacity, which can handle the processing load of the subsequent second-stage refiner 30 to improve the capacity and stability of the entire secondary refining process.

[0046] In some embodiments, the two-stage refiner 30 is a double-disc refiner, and the pulping method adopts a light knife with fine teeth. The width of the refiner teeth of the double-disc refiner is 1.8-2 times the target fiber length of pulping. In this way, by optimizing the tooth width of the refiner teeth, the pulp processed by the circulating beating device 10 can be further mechanically acted on to achieve fiber cutting and refinement, thereby improving the beating degree of the pulp, that is, it helps to swell the fibers and make the fibers easier to combine, thereby improving the forming quality of the paper.

[0047] S400. The pulp after the secondary refining treatment is transported to the papermaking pool.

[0048] In specific implementation, the pulp after the secondary refining treatment is transported to the second-stage post-grinding pulp tank 31, in which the pulp can be further treated to remove impurities and be homogenized to prepare for the final papermaking process.

[0049] In other examples, it is understood that the required beating degree for specialty papers is usually 85-98 0SR (beating degree), and for special paper production lines that require higher beating degrees, such as Figure 4 As shown, after the second-stage refiner 30, a third-stage refiner 80 and a corresponding third-stage post-refining pool 81 can be provided to further improve the pulp beating degree to meet the high beating degree of different types of specialty paper (such as 98 0 SR) requirements.

[0050] In summary, the special pulp beating method provided in this embodiment, through the synergistic effect of multi-stage refining and cyclic beating, and the two are carried out simultaneously in the entire pulping process, can effectively solve the key problems such as energy consumption control, fiber structure protection, and beating uniformity in special paper production, and can effectively save refining time, and achieve stable pulp quality and effective control of production costs under high beating degree requirements.

[0051] Specifically, if Figure 2 As shown, the circulating pulping device 10 comprises:

[0052] The barrel body 11 is arranged vertically, and a pulp inlet 111 is arranged at the top, and a pulp outlet 112 is arranged at the bottom;

[0053] The flow guide portion 12 is vertically arranged in the barrel body 11;

[0054] Among them, the slurry inlet 111 and the slurry outlet 112 are connected to form a slurry channel 13, and the guide part 12 is used to guide the slurry in the slurry channel 13 to fall along the circumferential distribution of the barrel body 11, so that the distribution density difference of the slurry on the cross section of the barrel body 11 does not exceed a preset threshold.

[0055] By utilizing this structural design, the barrel body 11 is vertically arranged and a pulp inlet pipe 111 and a pulp outlet pipe 112 are arranged on the barrel body 11 to form a pulp channel 13. In the pulp channel 13, the pulp can be guided by the guide part 12 under the action of its own gravity, and slowly fall down from top to bottom along the circumference of the barrel body 11 in a uniform distribution without backmixing and avoiding agglomeration and unevenness during the pulping process. In this way, the pulp has been pre-dispersed before entering the first or second stage refiner. On the one hand, it means that the intensity of pulping required in the refiner can be reduced, thereby reducing the energy consumption of the refiner. On the other hand, it can avoid fiber damage during the pulping process when the pulp is unevenly agglomerated, and can avoid load fluctuations of the first refiner 20 or the second stage refiner 30 caused by pulp agglomeration, thereby reducing the difference in pulp quality caused by load fluctuations.

[0056] In some embodiments, Figure 2 As shown, a plurality of guide portions 12 are provided in the barrel body 11 through a support frame 14, and the plurality of guide portions 12 are evenly arranged in the slurry channel 13 along the vertical direction, and the radial cross-sectional area at the upper and lower ends of each guide portion 12 gradually decreases in opposite directions to form a conical structure.

[0057] During specific implementation, multiple guide portions 12 are located directly below the slurry inlet 111. The conical structure of the guide portion 12 is utilized to gradually disperse the slurry during the descent process, thereby increasing the surface area of ​​the slurry in contact with the air, which is helpful for the swelling and fibrillation of the fibers. In addition, multiple guide portions 12 are evenly spaced in the vertical direction to reduce the need for pumping, so that the slurry can be dispersed in each descent process, thereby enhancing the fluidity and dispersion effect of the slurry, which not only improves the pulping efficiency, but also helps to achieve more uniform and high-quality pulping.

[0058] In some examples, an exhaust port 15 is provided at the top of the barrel body 11, and a liquid level meter 16 and a temperature sensor 17 are provided at the bottom, wherein the exhaust port 15 can release steam or gas that may be generated inside the barrel body 11, reduce pressure, avoid equipment damage or safety accidents, and improve the safety of the production process; the liquid level meter 16 can accurately display the slurry level in the barrel body 11, ensure the stability of the liquid level during the slurry treatment process, avoid overflow or insufficient slurry, and the temperature sensor 17 allows real-time monitoring of the slurry temperature in the barrel body 11, and accurately control the process to ensure that the pulping conditions are always in the best state.

[0059] In some embodiments, Figure 2 As shown, in order to avoid adverse effects of excessively high or low temperatures on the fibers, in steps S200 and S300, the slurry temperature is controlled at 40°C to 50°C by the jacket heat exchange structure 50 of the circulating pulping device 10.

[0060] In the actual pulping process, the pulp treated by the first-stage pulping machine 20 or the second-stage pulping machine 30 will increase in temperature after several cycles of pulping. If the temperature is too high, the chemical properties of cellulose will be destroyed. If the temperature is too low, it will be difficult to disperse. Therefore, cooling water enters from the cooling water inlet 51 through the jacket heat exchange structure 50, removes the heat of the pulp and is discharged from the cooling water outlet 52 to accurately control the temperature of the pulp to ensure that it is maintained in the range of 40°C to 50°C, providing the best processing conditions for the fiber.

[0061] In some embodiments, Figure 2 As shown, in order to return part of the pulp to the circulating pulping device 10 to achieve multi-stage pulping and stabilize the pulp inlet pressure of the pulper, it also includes a high-level box 40 arranged at a height higher than the first-stage pulper 20 and the second-stage pulper 30; the high-level box 40 includes a box body and a pulp inlet 41, a pulp outlet 42 and a return pipe 43 all arranged on the box body, the pulp inlet 41 is connected to the pulp outlet 112 of the corresponding circulating pulping device 10 through a pipeline, the pulp outlet 42 is connected to the corresponding first-stage pulper 20 or the second-stage pulper 30 through a pipeline, and the return pipe 43 is connected to the pulp inlet 111 of the corresponding circulating pulping device 10.

[0062] Utilizing this structural design, the high-level box 40 is designed to allow the pulp processed by the circulating beating device 10 to flow naturally under the action of gravity, maintaining a constant pulp inlet pressure of the first-stage refiner 20 or the second-stage refiner 30, thereby ensuring the efficiency and quality of the refiner; at the same time, through the reflux pipe 43, part of the pulp can flow back to the circulating beating device 10 for multiple cycles of beating, making the fiber dispersion more uniform, effectively meeting the requirements of special paper for high beating degree.

[0063] In some embodiments, in steps S200 and S300, the first-stage refiner 20 and the second-stage refiner 30 both perform refining at constant power. In this embodiment, the constant power ensures that each batch of pulp is subjected to the same refining force, thereby ensuring the consistency of the beating degree and quality, and ensuring the predictability and repeatability of various parameters in the production process.

[0064] In some embodiments, Figure 3 As shown, in order to ensure the purity of the pulp and avoid wear or damage to the refiner, an iron remover 60 is provided in front of the pulp inlet port 111 of the circulating pulping device 10, and the magnetic induction intensity of the iron remover 60 is 10000-12000GS.

[0065] In this embodiment, the use of the iron remover 60 can effectively remove fine iron impurities in the pulp. One purpose is to ensure the purity of the pulp and provide a guarantee for achieving the electrical performance indicators of special papermaking fibers. Another purpose is to protect the grinding teeth of the pulping machine from wear or damage, reduce the risk of equipment downtime due to maintenance, and reduce maintenance costs.

[0066] In some embodiments, Figure 3 As shown, in order to ensure the uniformity of slurry transportation, the circulating beating device 10 and the high-level box 40, the high-level box 40 and the first-stage refiner 20, the high-level box 40 and the second-stage refiner 30, the first-stage refiner 20 and the circulating beating device 10, and the second-stage refiner 30 and the circulating beating device 10 are all connected through a variable frequency controlled slurry supply pump 70. In this embodiment, the variable frequency controlled slurry supply pump 70 can adjust the flow rate and pressure as needed to meet the specific requirements of slurry transportation in different process stages.

[0067] The special pulp beating method provided in this embodiment adopts graded and segmented circulating pulping, which can not only efficiently increase the pulp beating degree to the pulping index requirements of special paper, but also ensure the uniformity of the pulp in and out during the pulping process through the design of the circulating pulping device, effectively avoiding the backmixing phenomenon, and while ensuring the quality of the pulp, significantly reducing the energy consumption of the pulping process, achieving the goal of energy saving and consumption reduction, and effectively solving the contradiction between high beating degree and energy consumption control in special paper production.

[0068] In the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0069] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A special pulp beating method, comprising a circulating beating device and at least one first-stage refiner and one second-stage refiner, characterized in that: The following steps are involved: S100. Desanding the pulp stock; S200. The desanded pulp is transported to a first-stage pulping machine for a first pulping process, wherein the first pulping process includes: The raw pulp is circulated and beaten once by an independent circulating pulping device and then transported to a first-stage pulping machine; The outlet of the first refiner is divided into a path and transported to the circulating pulping device for secondary circulating pulping; S300. The pulp after the primary refining treatment is transported to the second-stage refiner for secondary refining treatment, wherein the secondary refining treatment includes: The pulp is circulated and beaten once by an independent circulating pulping device and then transported to the second-stage refiner; The outlet of the second-stage refiner is divided into a path and transported to the first circulation beating device for secondary circulation beating; S400. The pulp after the secondary refining treatment is transported to the papermaking pool.

2. The special pulp beating method according to claim 1, characterized in that: The circulating pulping device comprises: The barrel body is arranged vertically, with a pulp inlet opening at the top and a pulp outlet opening at the bottom; The flow guide part is vertically arranged in the barrel body; The slurry inlet and outlet are connected to form a slurry channel, and the guide portion is used to guide the slurry in the slurry channel to fall along the circumferential distribution of the barrel body, so that the distribution density difference of the slurry on the cross-section of the barrel body does not exceed a preset threshold.

3. The special pulp beating method according to claim 2, characterized in that: The guide parts are provided in plurality in the barrel body through a support frame, and the guide parts are arranged equidistantly in the pulp lowering channel along the vertical direction, and the radial cross-sectional area of ​​the upper and lower ends of each guide part gradually decreases in opposite directions to form a conical structure.

4. The special pulp beating method according to claim 2 or 3, characterized in that: It also includes a high-position box arranged at a height higher than the first-stage refiner and the second-stage refiner; the high-position box includes a box body and a pulp inlet, a pulp outlet and a return pipe all arranged on the box body, the pulp inlet is connected to the pulp outlet of the corresponding circulating pulping device through a pipeline, the pulp outlet is connected to the corresponding first-stage refiner or the second-stage refiner through a pipeline, and the return pipe is connected to the pulp inlet of the corresponding circulating pulping device.

5. The special pulp beating method according to claim 1, characterized in that: In steps S200 and S300, the first-stage refiner and the second-stage refiner both perform refining at a constant power.

6. The special pulp beating method according to claim 1 or 5, characterized in that: The pulping degree after one refining treatment reaches 55-65 0 SR.

7. The special pulp beating method according to claim 6, characterized in that: The first stage refiner is a cylindrical refiner, and the second stage refiner is a double-disc refiner. The width of the refiner teeth of the double-disc refiner is 1.8-2 times the length of the target fiber for pulping.

8. The special pulp beating method according to claim 1, characterized in that: In steps S200 and S300, the slurry temperature is controlled at 40°C to 50°C by the jacket heat exchange structure of the circulating pulping device.

9. The special pulp beating method according to claim 2, characterized in that: An iron remover is provided in front of the pulp inlet pipe of the circulating pulping device, and the magnetic induction intensity of the iron remover is 10000-12000GS.

10. The special pulp beating method according to claim 4, characterized in that: The circulating beating device and the high-position box, the high-position box and the first-stage refiner, the high-position box and the second-stage refiner, the first-stage refiner and the circulating beating device, and the second-stage refiner and the circulating beating device are all connected through a frequency-converter-controlled pulp supply pump.

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