A pulp delivery system for improving longitudinal basis weight fluctuations in paper production

Abstract

This utility model discloses a pulp delivery system for improving longitudinal basis weight fluctuations in paper production, comprising a pulp mixing tank, a mixing pump, a paper machine pulp tank, a paper machine pulp pump, an external white water tank, a descaling pump, a first-stage descaling device, a flushing pump, and a core wire for paper production. A set of conical sleeve structures, installed in the external white water tank via pipelines, is provided between the paper machine pulp pump and the descaling pump. Another set of conical sleeve structures, again installed in the external white water tank via pipelines, is provided between the outlet of the descaling pump and the flushing pump. The pipeline between the outlet of the descaling pump and the external white water tank also branches off to a return pipe that returns the descaled, high-quality pulp to the outlet of the paper machine pulp pump before the descaling pump. A regulating valve is installed on the return pipe to ensure the pressure differential of the first-stage descaling device is simultaneously matched to the demand of the flushing pump, preventing pulp overflow from the external white water tank sleeve and ensuring the stability of the longitudinal basis weight of the paper.

Description

Technical Field

[0001] This utility model relates to the field of longitudinal basis weight fluctuation control technology for paperboard, and in particular to a pulp delivery system for improving longitudinal basis weight fluctuation in paper. Background Technology

[0002] White cardboard, due to its excellent physical properties and good printability, is widely used in the field of fine packaging, with a basis weight range of 180g / m². 2 -400g / m 2 White cardboard typically consists of three layers of pulp: a surface layer, a core layer, and a bottom layer. Due to its high printing requirements and diverse post-processing techniques, white cardboard has strict requirements for its longitudinal basis weight stability (i.e., the range of basis weight fluctuation along the paper machine's running direction). Good longitudinal basis weight stability helps improve the printability of the finished paper, reducing problems such as paper shaking and color difference caused by basis weight fluctuations during printing. Simultaneously, it improves the processing adaptability of the finished paper, ensuring uniform stress during die-cutting and creasing, and preventing burst lines or poor forming.

[0003] The main source of longitudinal basis weight fluctuation in paper is the basis weight fluctuation of the core layer. The core layer occupies a dominant position in the main structure, accounting for more than 60% of the paper's basis weight, providing thickness, stiffness, and elasticity, and improving the paperboard's indentation adaptability. In existing white cardboard core layer flow systems, after passing through a desander for screening and desandering, the good pulp enters the flushing pump along the pipeline. The pulp is mixed and diluted with white water from the external white water tank during the flushing pump's suction process. Specifically, the mixing and dilution process is achieved by connecting a desander and the good pulp pipeline to the inlet of the flushing pump, and then connecting a conical pipe from the external white water tank at the inlet of the flushing pump for mixing and dilution. This flushing process dilutes the pulp to ensure uniform fiber dispersion and reduce fiber flocculation. Since the frequency of the flushing pump is determined by the paper machine speed and the pulp concentration at the wire, when the machine speed is slow and the core layer basis weight is low, the frequency of the flushing pump will decrease. At this time, the demand of the flushing pump is less than the good pulp throughput at the outlet of the first-stage descaling unit. The good pulp in the first-stage descaling unit cannot be completely pumped away by the flushing pump, and the pulp will overflow from the sleeve opening of the conical tube into the external white water tank, which will lead to an increase in the pulp concentration in the external white water tank. During flushing, the pulp concentration is unstable, ultimately causing fluctuations in the longitudinal basis weight of the final paper. To reduce the pulp overflow into the external white water tank, the throughput of the first-stage descaling unit needs to be reduced. This will lead to a decrease in the pressure differential of the descaling unit, which will not only reduce the descaling efficiency but also easily cause blockage of the descaling unit cone.

[0004] Therefore, it is urgent to improve the existing pulp delivery system to avoid the mismatch between the pulp supply from the desander and the demand from the flushing pump, which would affect the quality of the finished paper. Utility Model Content

[0005] This invention provides a pulp delivery system to improve longitudinal basis weight fluctuations in paper production. The system returns the pulp from the good pulp pipeline of the first-stage desander to the pulp pump of the first-stage desander. The return flow rate is adjusted by a regulating valve to ensure the pressure differential of the first-stage desander while simultaneously matching the demand of the flushing pump. This prevents the pulp from overflowing from the white water tank sleeve into the white water tank outside the machine, ensuring the stability of the longitudinal basis weight of the paper and effectively improving the production efficiency of paper production.

[0006] The technical solution adopted by this utility model to solve its technical problem is: A pulp delivery system for improving longitudinal basis weight fluctuation in papermaking, used for adjusting and controlling the core layer pulp during flushing, includes a pulp mixing tank, a mixing pump, a paper machine pulp tank, a paper machine pulp pump, an external white water tank, a descaling pump, a first-stage descaling device, a flushing pump, and the core wire of the papermaking process. The pulp mixing tank, the mixing pump, the paper machine pulp tank, and the paper machine pulp pump are connected sequentially through pipelines. A set of conical sleeve structures is provided between the paper machine pulp pump and the deslagging pulp pump, which are installed in the external white water tank through pipelines for mixing and diluting the pulp before deslagging and then pumping it into the first-stage deslagging device for deslagging and filtration by the deslagging pulp pump. Between the outlet of the slag removal pump and the slurry pump, there is another set of conical sleeve structures installed in the external white water tank through a pipeline. This structure is used to mix and dilute the good slurry after slag removal before it is pumped out by the slurry pump. The good slurry pumped out by the slurry pump is supplied to the core wire to form paper. The pipeline between the outlet of the deslagging slurry pump and the external white water tank is also branched to a return pipe that returns the deslagging good slurry to the outlet of the paper machine slurry pump before the deslagging slurry pump, is used to match the demand of the flushing pump and prevent slurry from overflowing from the conical sleeve of the external white water tank into the external white water tank. The return pipe is equipped with a regulating valve to adjust the slurry return flow rate.

[0007] Preferably, the conical sleeve structure inside the external white water tank includes a conical sleeve that communicates with the white water inside the external white water tank and is connected to the pump body at its constricted end, and a slurry pipe that is fitted into the conical funnel opening of the conical sleeve. The conical sleeve communicates with the white water inside the external white water tank and is connected to the pump body at its constricted end. The core layer slurry in the slurry pipe is mixed and diluted with the white water introduced at the conical funnel opening of the conical sleeve and then pumped out by the connected pump body.

[0008] Preferably, the pipeline between the slurry pump and the core mesh is further provided with a pressure screen to pressurize the pumped good slurry and a headbox to buffer the pumped good slurry.

[0009] The beneficial effects of this utility model are: The pulp is mixed and diluted before slag removal by two sets of parallel conical sleeve structures in the external white water tank. The pulp is then diluted by flushing to ensure uniform fiber dispersion and reduce fiber flocculation. The pulp is then pumped into a slag remover by a slag removal pump for slag removal and filtration. Next, the slag-removed good pulp is mixed and diluted again by another set of conical sleeve structures and then pumped out by a flushing pump. The pumped-out good pulp is supplied to the core wire for papermaking.

[0010] Furthermore, the pipeline between the outlet of the deslagging slurry pump and the external white water tank is also branched to a return pipe and a regulating valve that return the deslagging good slurry to the paper machine slurry pump outlet before the deslagging slurry pump. The return pipe and regulating valve ensure the pressure difference of a deslagging device while simultaneously matching the demand of the flushing pump, preventing slurry from overflowing from the conical sleeve of the external white water tank into the external white water tank, thus ensuring the stability of the longitudinal basis weight of the paper.

[0011] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating the working principle of this utility model; Figure 2 yes Figure 1 An enlarged schematic diagram of the tapered sleeve structure in the image. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. Terms such as "center," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0015] Furthermore, in the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be reasonably determined in conjunction with the specific content of the technical solution.

[0016] A pulp delivery system for improving longitudinal basis weight fluctuations in paper production, such as Figure 1 As shown, the system is used for adjusting and controlling the core layer pulp during flushing. It includes a pulp mixing tank 1, a mixing pump 2, a paper machine pulp tank 3, a paper machine pulp pump 4, an external white water tank 5, a descaling pump 6, a first-stage descaling device 7, a flushing pump 8, and the core wire 9 for paper production. The pulp mixing tank 1, mixing pump 2, paper machine pulp tank 3, and paper machine pulp pump 4 are connected sequentially by pipelines. A pipeline is installed between the paper machine pulp pump 4 and the descaling pump 6, passing through the external white water tank 5, to mix and dilute the pulp before descaling before pumping it into the first-stage descaling device 7 by the descaling pump 6. A set of conical sleeve structures for slag removal and filtration; between the outlet of the slag removal slurry pump 6 and the slurry pump 8, there is another set of conical sleeve structures installed in the external white water tank 5 through a pipeline to mix and dilute the good slurry after slag removal and pump it out by the slurry pump 8. The good slurry pumped out by the slurry pump 8 is supplied to the core wire 9 for papermaking; at the same time, a pressure screen 14 for pressurizing the pumped good slurry and a headbox 15 for buffering the pumped good slurry are also installed on the pipeline between the slurry pump 8 and the core wire 9. The pulp is mixed and diluted before slag removal through two sets of parallel conical sleeve structures in the external white water tank 5. The pulp is diluted by flushing to ensure uniform fiber dispersion and reduce fiber flocculation. Then, the pulp is pumped into a first-stage slag remover 7 by the slag removal pump 6 for slag removal and filtration. Next, the slag-removed good pulp is mixed and diluted again through another set of conical sleeve structures and then pumped out by the flushing pump 8. The pumped-out good pulp is supplied to the core wire 9 for paper forming.

[0017] Among them, such as Figure 2 As shown, the conical sleeve structure inside the external white water tank 5 includes a conical sleeve 12 that is connected to the white water in the external white water tank and has its constricted end connected to the pump body, and a slurry pipe 13 that is inserted and installed at the conical flared end of the conical sleeve 12. The conical sleeve 12 is connected to the white water in the external white water tank 5 and has its constricted end connected to the pump body. The core layer slurry in the slurry pipe 13 is mixed and diluted with the white water introduced at the conical flared end of the conical sleeve 12 and then pumped out by the connected pump body.

[0018] like Figure 1As shown, a branch line is also connected between the outlet of the deslagging slurry pump 6 and the external white water tank 5 to a return pipe 10, which returns the deslagging good slurry to the outlet of the paper machine slurry pump 4 before the deslagging slurry pump 6, matches the demand of the flushing pump 8, and prevents slurry from overflowing from the conical sleeve of the external white water tank 5 into the external white water tank 5. A regulating valve 11 is installed on the return pipe 10 to adjust the slurry return flow rate. The return pipe 10 and the regulating valve 11 ensure the pressure difference of a section of the deslagging device 7 while simultaneously matching the demand of the flushing pump 8, preventing slurry from overflowing from the conical sleeve of the external white water tank 5 into the external white water tank 5, and ensuring the stability of the longitudinal basis weight of the paper.

[0019] The above-described embodiments are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. All equivalent changes made in accordance with the shape, structure and principle of this utility model should be covered within the protection scope of this utility model.

Claims

1. A pulp delivery system for improving longitudinal basis weight fluctuation in papermaking, used for adjustment and control during core layer pulp flushing, characterized in that, It includes a pulp mixing tank (1), a mixing pump (2), a paper machine pulp tank (3), a paper machine pulp pump (4), an external white water tank (5), a descaling pump (6), a first-stage descaling device (7), a flushing pump (8), and a paper core wire (9). The pulp mixing tank (1), the mixing pump (2), the paper machine pulp tank (3), and the paper machine pulp pump (4) are connected in sequence through pipelines. A set of conical sleeve structures is provided between the paper machine pulp pump (4) and the slag removal pulp pump (6) and installed in the external white water tank (5) through a pipeline for mixing and diluting the pulp before slag removal and then pumping it into the first-stage slag remover (7) for slag removal and filtration by the slag removal pulp pump (6). Between the outlet of the slag removal pump (6) and the slurry pump (8), there is another set of conical sleeve structures installed in the external white water tank (5) through a pipeline to mix and dilute the good slurry after slag removal and pump it out by the slurry pump (8). The good slurry pumped out by the slurry pump (8) is supplied to the core wire (9) to form paper. The pipeline between the outlet of the deslag pump (6) and the external white water tank (5) is also branched to a return pipe (10) that returns the deslag-removed good pulp to the outlet of the paper machine pulp pump (4) before the deslag pump (6) pumps the pulp, is used to match the demand of the flushing pump (8) and prevent the pulp from overflowing from the conical sleeve of the external white water tank (5) into the external white water tank (5). The return pipe (10) is equipped with a regulating valve (11) for adjusting the pulp return flow.

2. The pulp delivery system for improving longitudinal basis weight fluctuation in papermaking according to claim 1, characterized in that: The conical sleeve structure inside the external white water tank (5) includes a conical sleeve (12) that is connected to the white water in the external white water tank and has its constricted end connected to the pump body, and a slurry pipe (13) that is inserted and installed at the conical flared end of the conical sleeve (12). The conical sleeve (12) is connected to the white water in the external white water tank (5) and has its constricted end connected to the pump body. The core layer slurry in the slurry pipe (13) is mixed and diluted with the white water introduced at the conical flared end of the conical sleeve (12) and then pumped out by the connected pump body.

3. The pulp delivery system for improving longitudinal basis weight fluctuation in papermaking according to claim 1, characterized in that: The pipeline between the slurry pump (8) and the core mesh (9) is also equipped with a pressure screen (14) for pressurizing the pumped good slurry and a headbox (15) for buffering the pumped good slurry.

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