Paper, pulp and method of treating the same

Abstract

The application provides a paper product, a paper pulp and a processing method thereof; the processing method comprises the following steps: multiple pulp washing; using a pulp squeezing machine to perform pulp beating, and conveying white water obtained by the pulp beating to other pulp lines; and inputting the pulp after the pulp beating into a pulp feeding tank. The processing method of the paper pulp provided by the application utilizes the surplus capacity of the pulp squeezing machine of the existing pulp beating workshop in the factory, improves the pulp washing efficiency through process flow technical improvement of part of the pipelines and equipment, improves the pulp cleanliness through the process technical method, improves the pulp COD, PCD and odor value, improves the pipeline pulp feeding capacity, meets the quality and pulp demand of the paper machine for the chemical pulp, and further improves the proportion of the chemical pulp, and reduces the comprehensive cost per ton of paper.

Description

Technical Field

[0001] This application relates to the technical field of papermaking pulp, specifically to a paper product, paper pulp, and a method for processing the same. Background Technology

[0002] In recent years, with the continuous release of domestic white cardboard production capacity, market competition has become increasingly fierce. In order to further optimize the cost per ton of paper and enhance market competitiveness, it is necessary to further increase the proportion of relatively low-cost chemimechanical pulp and correspondingly reduce the proportion of high-cost N pulp and L pulp, thereby achieving the goal of reducing the cost per ton of paper.

[0003] However, to ensure that the paper strength and other quality standards are met, while increasing the proportion of chemimechanical pulp, it is necessary to increase the tensile strength of the chemimechanical pulp. Therefore, it is necessary to increase the amount of pulping alkali. With the increase in alkali, the amount of leached substances such as lignin in the pulping process also increases. Under the existing pulping production line washing equipment and process conditions, it is impossible to meet the paper machine's requirements for the cleanliness indicators of chemimechanical pulp (COD, PCD, odor, etc.). This leads to many problems such as high chemical consumption per unit of paper machine wet end, significant decrease in chemical efficiency, increase in paper machine wastewater load, and unstable paper machine operation. Ultimately, the overall cost per ton of paper increases instead of decreasing. Summary of the Invention

[0004] The first aspect of this application provides a method for processing pulp, the method comprising:

[0005] Multiple washing and pulping;

[0006] The pulp is processed using a pulp press, and the white water obtained from pulping is then transported to other pulp lines.

[0007] The slurry after being prepared is fed into the slurry delivery tank.

[0008] In some embodiments, the step of forming the pulp using a pulp press is performed in parallel with the final washing process.

[0009] In some embodiments, the amount of pulp processed in the step of forming the pulp using a pulp press accounts for more than one-third of the total volume of the pulp line.

[0010] In some embodiments, the pulp dryness obtained in the step of pulping with a pulper is 40-45%.

[0011] In some embodiments, in the step of using a pulp press to form pulp, the pulp press is a double-wire pulp press, which also performs the tasks of other pulp lines. The step of using a pulp press to form pulp utilizes the spare capacity of the double-wire pulp press.

[0012] In some embodiments, the step of forming the pulp using a pulp press may further include: conveying the pulp to be formed to a pulping tank before the step of forming the pulp using a pulp press.

[0013] In some embodiments, before the step of feeding the pulp after pulping into the pulping tank, the method further includes: crushing the pulp using a pulper and diluting the crushed pulp with paper machine white water.

[0014] In some embodiments, the processing method further includes conveying the slurry to the pulper using a conveying screw.

[0015] Secondly, embodiments of this application provide a pulp, which is prepared using the processing method described in the above embodiments.

[0016] Thirdly, this application provides a paper product, which is obtained by preparing the pulp as described in the above embodiments.

[0017] The pulp processing method provided in this application utilizes the surplus capacity of the existing pulp mill in the factory's pulping workshop. Through technological modifications to some pipelines and equipment, it improves pulp washing efficiency, thereby enhancing pulp cleanliness. This process improves the COD, PCD, and odor values ​​of the pulp, while also increasing the pulp delivery capacity of the pipelines to meet the paper machine's requirements for the quality and usage of chemimechanical pulp. Ultimately, this increases the proportion of chemimechanical pulp and reduces the overall cost per ton of paper. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of an embodiment of the pulp processing method of this application;

[0020] Figure 2 This is a schematic diagram of a pulp line according to an embodiment of the pulp processing method of this application;

[0021] Figure 3 This is a schematic diagram of the pulp line according to another embodiment of the pulp processing method of this application;

[0022] Figure 4 This is a schematic diagram of a pulp line in another embodiment of the pulp processing method of this application;

[0023] Figure 5 yes Figure 4 A schematic diagram of a specific embodiment of the pulping step. Detailed Implementation

[0024] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the application. Similarly, the following embodiments are only some, not all, embodiments of the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0025] The terms "first," "second," and "third" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movement of components in a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to these processes, methods, products, or devices.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] Please see Figure 1 , Figure 1 This is a schematic flowchart of an embodiment of the pulp processing method of this application. The processing method in this embodiment includes, but is not limited to, the following steps.

[0028] Step S100: Wash the pulp multiple times.

[0029] Please refer to the following: Figure 2 , Figure 2This is a schematic diagram of a pulp line according to an embodiment of the pulp processing method of this application. In this embodiment, the multiple pulp washing steps may include a first pulp washing 201, a second pulp washing 202, and a third pulp washing 203.

[0030] Please continue reading. Figure 1 In this embodiment, the pulp processing method further includes step S200, which involves using a pulp press to form the pulp and then conveying the white water obtained from the pulping process to other pulp lines.

[0031] The white water obtained from the pulping process 204 contains impurities and can be transferred to other pulp lines 205 with relatively lower pulp requirements to save water. Optionally, the extruder used in this embodiment can be a double-wire extruder.

[0032] Please continue reading. Figure 1 In this embodiment, the pulp processing method further includes step S300, which involves inputting the pulp after papermaking into a pulp feeding tank.

[0033] In this step, the pulp after pulping can be conveyed to the pulp tank 206 and then to the paper machine 207.

[0034] Please see Figure 3 , Figure 3 This is a schematic diagram of a pulp line according to another embodiment of the pulp processing method of this application. Unlike the previous embodiments, in this embodiment, pulp forming 204 and the final washing (the third washing 203 in this embodiment) are performed in parallel. The amount of pulp processed during pulp forming 204 accounts for more than one-third of the total pulp line volume. The pulp dryness obtained in pulp forming 204 is 40-45%.

[0035] Optionally, in this embodiment, the pulping machine used in the pulping process is a double-net pulping machine. The double-net pulping machine is a large-scale pulp dewatering device. Its main principle is: using two dewatering nets, the 4-6% concentration pulp is squeezed through four sets of pressure rollers, so that the water in the pulp placed between the upper and lower dewatering nets is removed. Finally, the pulp concentration at the outlet of the double-net pulping machine is increased to 40-45%, effectively removing the filtrate (i.e., white water) from the pulp, and further improving the purity of the pulp.

[0036] This dual-net pulping machine also performs the tasks of other pulp production lines. In this embodiment, the pulping process of the pulp production line utilizes the surplus capacity of the dual-net pulping machine. If a washing machine is added, the pulping process needs to be redesigned, involving a series of steps such as technical modifications to the pulp system process, ordering of new equipment, civil engineering installation and commissioning, etc. This results in a large initial investment, a long technical modification period, and a long investment payback period. However, the solution in this embodiment utilizes the surplus capacity of the dual-net pulping machine in other pulp production lines, which can save the above-mentioned costs.

[0037] Please see Figure 4 , Figure 4 This is a schematic diagram of the pulp flow line of another embodiment of the pulp processing method of this application. The pulp flow line in this embodiment includes the pulp flow line indicated by the dark arrow and the water system flow line indicated by the light arrow. The pulp flow line includes, in sequence: 1# bleaching tower 401, 1# roller washing 402, 2# bleaching tower 403, 2# SCP (spiral mesh belt washer) washing 404, 3# SCP (spiral mesh belt washer) washing 405, 4# SCP (spiral mesh belt washer) washing 406, low concentration screening section 407, multi-disc thickener 408, medium concentration storage tower 409, 5# SCP (spiral mesh belt washer) washing 410, pulping 411 parallel to 5# SCP (spiral mesh belt washer) washing 410, pulp feeding tank 412, and paper machine 413.

[0038] The water system includes: wastewater tank 1 (414), turbid filtrate recovery tank 415, filtrate tank 2 (416), filtrate tank 3 (417), filtrate tank 418, turbid filtrate tank 419, filtrate tank 5 (420), turbid filtrate buffer tank 421, pulp line white water tower 422, and system makeup water 423. The connections between the tanks and between them and different equipment in the pulp process are shown by arrows in the figure, and will not be described in detail here.

[0039] Please refer to the following: Figure 5 , Figure 5 yes Figure 4A schematic diagram of a specific embodiment of the pulping process is shown, wherein the pulping process specifically includes the following steps. The pulp to be pulped is conveyed to the pulping tank 4111, and then pulped using the double-wire extruder 4112 to obtain pulp with a dryness of 40-45%. Next, the pulp is conveyed to the No. 2 pulper 4114 by the conveying screw 4113. After being squeezed and dewatered by the double-wire extruder 4112, the pulp is in lumps, which is not conducive to subsequent pulping. It must be broken down by the crushing screw. Then, the crushed pulp is conveyed to the pulper (i.e., the No. 2 pulper 4114) by the lifting inclined screw and the horizontal conveying screw. The No. 2 pulper 4114 is used to crush the pulp. At the same time, paper machine white water 4115 is added to dilute the crushed pulp. Specifically, paper machine core layer white water can be pumped from the paper machine white water tower to the pulping workshop. The flow rate of paper machine white water is adjusted according to the amount of pulp conveyed after crushing to maintain the concentration of diluted pulp at 4-5%. After uniform dilution, the pulp is pumped to the paper machine preparation workshop (in the pulping tank 412) for use. The cleanliness of the pulp after dewatering and dilution by the double-wire extruder is significantly improved, effectively enhancing the cleanliness of the pipe pulp, increasing the efficiency of wet-end chemical application in the paper machine, and simultaneously increasing the pipe pulp delivery capacity by 500-600 adt / d, reducing the amount of dry pulp added, and significantly lowering the dry pulp processing cost. In this embodiment, the white water generated during the pulping process of the double-wire extruder 4112 can be transported to the cardboard production line 424 or to the pulp workshop 425 for unified distribution and use. The production line in this embodiment can be used for producing cardboard such as food-grade cardboard, which requires higher cleanliness.

[0040] Tests were conducted according to the improved process method:

[0041] Implementation methods for improving the cleanliness and delivery rate of slurry in pipelines using a dual-net slurry press (see table below): Example 1: Dual-net slurry press capacity 146 adt (air-dried tons) / day, inlet slurry concentration 5%, outlet slurry dryness 42%; Example 2: Dual-net slurry press capacity 259 adt / day, inlet slurry concentration 5%, outlet slurry dryness 42%; Example 3: Dual-net slurry press capacity 421 adt / day, inlet slurry concentration 5%, outlet slurry dryness 42%; Example 4: Dual-net slurry press capacity 518 adt / day, inlet slurry concentration 5%, outlet slurry dryness 42%.

[0042]

[0043] Note: The total amount of pulp delivered through the pipeline in the table represents the sum of the two pulp lines (the food card pulp line (i.e., the pulp line in this embodiment) and the social card pulp line). The processing method in this embodiment is to perform papermaking on the food card pulp line to improve the cleanliness of the food card pulp line.

[0044] The data above shows that when the dual-wire extruder's processing capacity is <400 adt / d (wherein, the feed flow rate of the food cardboard pulp line in this embodiment is approximately half of the total feed volume of the pipe pulp, i.e., about 1200 adt / d), the improvement in the cleanliness (PCD, COD) of the pipe pulp in the paper feeder is not significant, and the increase in the total feed volume of the pipe pulp is relatively limited, which cannot meet the pulp requirements for making high basis weight paper types (≥2200 adt (air-dried tons) / d (day), which is generally about 90% dryness under workshop environmental conditions). When the dual-wire extruder's processing capacity is >400 adt / d (greater than...), the pulp quality is significantly improved. The cleanliness of the pulp in the feeder pipe (PCD, COD) is significantly improved, accounting for one-third of the total pulp volume. The total pulp volume in the feeder pipe is increased to over 2200 adt / d, which can meet the pulp requirements for making high basis weight paper. The main reason for this is that when the processing capacity of the double-wire extruder accounts for a low proportion of the total pulp volume in the feeder pipe, the improvement in the overall cleanliness of the pulp in the feeder pipe is not significant. It can be seen that when the processing capacity of the double-wire extruder is >400 adt / d, the cleanliness of the pulp in the feeder pipe can be effectively improved, while meeting the pulp requirements for making high basis weight paper. There is no need to add high-cost dry pulp, thereby effectively reducing production costs.

[0045] The pulp treatment method in this embodiment is simple and easy to operate. Since the double-wire extruder's processing capacity must be >400 adt / d to effectively improve the cleanliness of the pulp in the pipeline and simultaneously meet the pulp requirements for producing high-grammage paper, the current surplus capacity of the double-wire extruder in the pulping workshop can reach 600-800 adt / d. This allows for full utilization of existing plant conditions, effectively improving the cleanliness of the pulp in the pipeline while meeting the pulp requirements for producing high-grammage paper. This method maximizes the use of existing conditions, resulting in low cost, short technical upgrade period, and good results. By using the double-wire extruder to improve the dryness of the output pulp, the cleanliness of the pulp in the pipeline can be improved, effectively solving the problems of low pulp washing efficiency and insufficient pulp delivery capacity. This avoids low wet-end chemical efficiency and the need to add high-cost dry pulp, resulting in considerable overall benefits.

[0046] In addition, this application also provides a paper product, which can be formed from pulp obtained by the above embodiments. Other parameters and characteristics of the paper product are within the understanding of those skilled in the art and will not be described here.

[0047] The pulp processing method provided in this application utilizes the surplus capacity of the existing pulp mill in the factory's pulping workshop. Through technological modifications to some pipelines and equipment, it improves pulp washing efficiency, thereby enhancing pulp cleanliness. This process improves the COD, PCD, and odor values ​​of the pulp, while also increasing the pulp delivery capacity of the pipelines to meet the paper machine's requirements for the quality and usage of chemimechanical pulp. Ultimately, this increases the proportion of chemimechanical pulp and reduces the overall cost per ton of paper.

[0048] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. Any equivalent device or equivalent process transformation made based on the content of this application specification and drawings, or direct or indirect application in other related technical fields, are similarly included in the patent protection scope of this application.

Claims

1. A method for processing pulp, characterized in that, The processing method includes: Multiple washing and pulping; The pulp is processed using a pulp press, and the white water obtained from pulping is then transported to other pulp lines. The slurry after slurry preparation is fed into the slurry delivery tank; The step of using a pulp press to form pulp is carried out in parallel with the final pulp washing process, and the amount of pulp processed in the step of using a pulp press to form pulp accounts for more than one-third of the total volume of the pulp line. The pulp dryness obtained by the step of pulping the pulp using a pulper is 40-45%; In the step of using a pulp press to form pulp, the pulp press is a double-wire pulp press, which also performs the tasks of other pulp lines. The step of using a pulp press to form pulp utilizes the spare capacity of the double-wire pulp press.

2. The processing method according to claim 1, characterized in that, Before the step of using a pulp press to form pulp, the method further includes: conveying the pulp to be formed to a pulping tank.

3. The processing method according to claim 1, characterized in that, Before the step of feeding the pulp after pulping into the pulping tank, the method further includes: crushing the pulp using a pulper and diluting the crushed pulp with paper machine white water.

4. The processing method according to claim 3, characterized in that, The processing method also includes using a conveying screw to transport the slurry to the pulper.

5. A type of pulp, characterized in that, The pulp is prepared by the processing method described in any one of claims 1-4.

6. A paper product, characterized in that, The paper product is obtained by preparing the pulp according to claim 5.

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