Liujia pulping process

Abstract

The invention relates to the technical field of papermaking, and provides a Liuji wood pulping process which comprises the following steps: selecting qualified Liuji wood pieces and bamboo raw materials, and pretreating the Liuji wood pieces and the bamboo raw materials to obtain prepared materials; putting the prepared material into a digester, and digesting the prepared material by adopting a Veimede intermittent digesting C-mode combined with a steaming pre-impregnation mode, so as to obtain primary pulp; screening, oxygen removal, bleaching and multiple pulp washing treatments are carried out on the primary pulp, a novel resin control agent is added into the primary pulp during deoxidation and pulp washing to obtain finished pulp, and the finished pulp is fed into a pulp storage tower to be stored. Wood chips and bamboos are cooked by combining a Weimede intermittent cooking C-mode and a steaming pre-impregnation mode, so that the permeation speed and the reaction efficiency of an active chemical liquid medicine during cooking are improved, and the yield of a single pot is improved; a novel resin control agent is researched and developed, and is added into the primary pulp during deoxidation and pulp washing, so that the resin removal rate of the cryptomeria fortunei pulp is increased, and the influence of resin obstacles on papermaking is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of papermaking, in particular to a fir pulping process. Background Art

[0002] Traditional pulping processes typically use bamboo, eucalyptus, and other wood materials, resulting in high-quality pulp and low production costs. However, as demand for pulp increases year by year, the cost of procuring high-quality raw materials has also risen significantly, necessitating the search for alternative raw materials. Among these, Chinese fir is widely cultivated due to its favorable growing environment and short maturity cycle. Furthermore, its fiber length and quality are highly advantageous for papermaking, enabling the production of high-quality paper.

[0003] However, when using traditional pulping technology, the pulp of Japanese cedar has serious resin obstruction and low cleanliness, which leads to the problem of low product qualification rate. Therefore, it is necessary to improve the pulping technology of Japanese cedar. Summary of the Invention

[0004] In view of the fact that the existing fir pulping process has serious resin obstruction and low cleanliness, which leads to a low product qualification rate, one of the purposes of this application is to provide a fir pulping process, which improves the pulping process to increase the resin removal rate of the fir pulp and reduce the impact of resin obstruction on papermaking.

[0005] To achieve the above objectives, this application adopts the following technical solutions:

[0006] A willow fir pulping process comprises the following steps:

[0007] Step S10, selecting qualified Chinese fir wood chips and bamboo raw materials, and pre-treating the Chinese fir wood chips and bamboo raw materials to obtain prepared materials;

[0008] Step S20, placing the prepared material into a cooking pot, and steaming the prepared material using Valmet's batch cooking C-mode combined with steaming pre-impregnation mode to obtain a raw pulp;

[0009] Step S30, screening, oxygen deoxidation, bleaching and multiple pulp washing processes are performed on the raw pulp, and a novel resin control agent is added to the raw pulp during deoxidation and pulp washing to obtain a finished pulp;

[0010] Step S40: sending the finished pulp into a pulp storage tower for storage.

[0011] Preferably, the qualified Japanese cedar wood chips have a length of 20-30 mm, a width of 15-20 mm, a thickness of 3-5 mm, and a bulk density of 160-180 Bd kg / The qualified bamboo raw material has a length of 20-40 mm, a width of 5-15 mm, and a water content of 30%-50%.

[0012] Preferably, the qualified Japanese cypress wood chips and bamboo raw material are both mechanically peeled.

[0013] Preferably, the pretreatment of the Japanese cypress wood chips and bamboo raw material includes the following steps:

[0014] S101, the qualified Japanese cypress wood chips and bamboo raw material are stacked in a stock bin and left for 5-7 months;

[0015] S102, the Japanese cypress wood chips and bamboo raw material left for a period of time are transported to a swing screen for screening to obtain Japanese cypress wood chips and bamboo raw material of uniform size;

[0016] S103, the Japanese cypress wood chips and bamboo raw material of uniform size are transported to a washing machine for washing and dewatering to obtain raw material.

[0017] Preferably, in the step S20, active chemical liquor is added to the digester, and the main components of the active chemical liquor are sodium hydroxide, sodium sulfide and sodium sulfate.

[0018] Preferably, in the step S20, the cooking temperature of the raw material is controlled at 160-162℃, and the cooking time is controlled at 310-330 min.

[0019] Preferably, in the step S30, the multiple washing of the raw pulp is completed by using multiple double-roller extrusion machines.

[0020] Preferably, in the step S30, the preparation of the new resin control agent includes the following steps:

[0021] S301, deionized water is added to a reaction kettle, and the temperature is raised to 50℃; then a chelating agent is added, and stirring is performed until the chelating agent is completely dissolved;

[0022] S302, fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate are sequentially added to the reaction kettle, the temperature is maintained at 50-55℃, and continuous stirring is performed to form a transparent solution;

[0023] S303, sodium polyacrylate is slowly poured into the transparent solution, and nano-silicon dioxide is added, the stirring speed is increased, and continuous stirring is performed for 20 min to obtain a mixture;

[0024] S304, the mixture is transferred to a high-pressure homogenizer, and is processed for 2-3 cycles;

[0025] Step S305, the mixture after homogenization is sampled and the pH is detected, and after the pH is adjusted to 8.8~9.2 by using sodium hydroxide solution, it is filtered after being cooled to below 30℃, to obtain a new resin control agent.

[0026] Preferably, the steps S301~S303 are all stirred by using a high-speed dispersion stirrer, which is an anchor stirrer.

[0027] Preferably, in the step S301, the chelating agent is EDTA disodium salt.

[0028] Compared with the prior art, the beneficial effects of the present application are:

[0029] 1. By combining the Vimeco intermittent cooking C-mode and steaming pre-impregnation mode for cooking wood chips and bamboo, a large amount of gas and organic acid existing in the wood chips can be removed, the penetration speed and reaction efficiency of active chemical liquor during cooking are improved, and thus the single-pot yield is improved.

[0030] 2. A new resin control agent is developed, and it is added into the original pulp during deoxidization and pulp washing, the resin removal rate of cypress pulp is improved, and the influence of resin barrier on papermaking is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0032] Figure 1 The step schematic diagram of the cypress wood pulping process provided by the present application is shown in the figure;

[0033] Figure 2 The flow schematic diagram of the cypress wood pulping process provided by the present application is shown in the figure;

[0034] Figure 3 The manufacturing step schematic diagram of the new resin control agent provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0035] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are considered to be exemplary in nature rather than limiting.

[0036] The terms "comprising" and "having" and any variations thereof in the present application are intended to cover a non-exclusive inclusion. For example, a process, method, system, product or apparatus that comprises a list of steps or units is not necessarily limited to the listed steps or units, but can optionally further include additional steps or units that are not listed, or can optionally further include other steps or units inherent to such processes, methods, products or apparatus.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for describing particular embodiments only and is not intended to be limiting of the application. The use herein of the terms "and / or" includes a set of one or more associated listed items.

[0038] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase that in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that the embodiments described herein are merely examples from a multitude of embodiments that are of a potential use to one of ordinary skill in the art. It is further expressly understood that the use of relative terms are intended only to illustrate a particular feature or characteristic of an embodiment of the application, and not to denote an absolute requirement.

[0039] Embodiments of the application will now be described, by way of example only, with reference to the accompanying drawings.

[0040] Figure 1 A schematic diagram of the steps of the poplar wood pulping process provided by the present application is shown in Figure 1, Figure 2 A schematic diagram of the flow of the poplar wood pulping process provided by the present application is shown in Figure 2. The poplar wood pulping process comprises the following steps:

[0041] Step S10, selecting qualified Japanese cedar wood chips and bamboo raw materials, and pretreating the Japanese cedar wood chips and bamboo raw materials to obtain prepared materials;

[0042] Step S20, placing the prepared materials into a cooking pot, and using a Vimeco intermittent cooking C-mode combined with a steaming pre-impregnation mode to cook the prepared materials to obtain raw pulp;

[0043] Step S30, screening, oxygen removal, bleaching and multiple washing of the raw pulp, and adding a new type of resin control agent to the raw pulp during oxygen removal and washing to obtain finished pulp;

[0044] Step S40, sending the finished pulp to a pulp storage tower for storage.

[0045] The above process utilizes Valmet's batch cooking C-mode in the cooking system, adding a steam pre-impregnation mode for cooking wood chips and bamboo. This removes a significant amount of gas and organic acids from the wood chips, improving the penetration rate and reaction efficiency of the active chemical solution during cooking, shortening the cooking cycle and thus increasing single-pot output. Furthermore, a new resin control agent was developed and added to the raw pulp during deoxidation and washing, increasing the resin removal rate of the cedar pulp and reducing the impact of resin blockage on papermaking.

[0046] Among them, Valmet's intermittent cooking C-mode is an advanced pulping technology that can realize alternating pre-hydrolysis and alkaline cooking in the same cooking pot. Any scale formed during the pre-hydrolysis process will be dissolved during the alkaline cooking process, thereby reducing production losses and quality fluctuations; and steam pre-impregnation can make the Japanese cedar wood chips absorb water more evenly, which helps to improve the utilization rate of active chemical liquid, thereby reducing the amount of liquid and achieving better pulping effect. It should be noted that Valmet's intermittent cooking C-mode requires attention to the precise control of temperature, pressure and liquid addition to avoid uneven cooking, and the steam pre-impregnation mode requires ensuring uniform steam distribution and sufficient penetration of the raw materials to improve the softening effect.

[0047] Specifically, the cooking temperature of the prepared materials is controlled at 160-162°C, and the cooking time is controlled at 310-330 minutes, wherein the cooking time is from the start of loading the pot to the end of putting the pot out.

[0048] Furthermore, qualified Metasequoia wood chips and bamboo raw materials are all mechanically peeled, which can evenly remove the outer bark, reduce cortical residue, and ensure the effect and quality of subsequent processing.

[0049] Furthermore, in step S10, the moisture content and quality of the cedar and bamboo are tested to ensure that they are suitable for pulping. Qualified cedar wood chips have a length of 20-30 mm, a width of 15-20 mm, a thickness of 3-5 mm, and a bulk density of 160-180 Bdkg / , with a moisture content of 30%-60%; qualified bamboo raw materials are 20-40mm long, 5-15mm wide, and have a moisture content of 30%-50%. In addition, the Japanese cedar wood chips and bamboo raw materials must be uniform in size and clean, free of sand, mold, debris, long strips, large pieces, and large knots, so pre-treatment is required.

[0050] Specifically, the pretreatment of Japanese cedar wood chips and bamboo raw materials includes the following steps:

[0051] Step S101: stack qualified Japanese cedar wood chips and bamboo raw materials into a silo and let them stand for 5 to 7 months;

[0052] Step S102, transporting the cedar wood chips and bamboo raw materials after standing to a swing screen for screening to obtain cedar wood chips and bamboo raw materials of uniform size;

[0053] Step S103, the uniform-sized cedar wood chips and bamboo raw materials are transported to a washing machine for washing and dewatering to obtain the prepared material.

[0054] In the above technical solution, the purpose of storing the prepared material for 5-7 months is to improve the cooking efficiency, reduce impurities and stabilize the production supply through natural air drying, resin degradation and moisture balance.

[0055] Further, in this step S20, active chemical liquor, i.e., white liquor, is added to the digester, which is mainly used for cooking the fiber raw material to dissolve lignin and other non-fiber substances therein, so as to separate the fibers. The main components of the active chemical liquor are sodium hydroxide, sodium sulfide and sodium sulfate, wherein sodium hydroxide is used to provide a strong alkaline environment to destroy the structure of lignin, sodium sulfide is used to enhance the solubility of lignin and reduce cellulose degradation, and sodium sulfate is used to supplement the loss of sulfur, which will be converted into sodium sulfide in the recovery system, in addition, there is a small amount of sodium carbonate, which is generated by the side reaction in the recovery process. Since waste liquor, i.e., black liquor containing dissolved organic and inorganic substances, is generated after cooking, it is necessary to wash the pulp.

[0056] Specifically, in this step S30, multiple washing of the pulp is completed by using multiple double-roller pulp washers. Compared with a vacuum pulp washer, the double-roller pulp washer has better washing cleanliness and lower consumption of active chemical liquor. In addition, the pulp is bleached by using a D0 tower, an EOP tower and a D1 tower, which can improve the bleaching efficiency and quality of the finished pulp, and the bleaching and washing are alternately performed to ensure the cleanliness of the finished pulp.

[0057] Figure 3 The preparation steps of the novel resin control agent provided in the present application are shown in the schematic diagram. The preparation of the novel resin control agent includes the following steps:

[0058] Step S301, deionized water is added to the reaction kettle, and the temperature is raised to 50℃; then a chelating agent is added and stirred until it is completely dissolved;

[0059] Step S302, fatty alcohol polyoxyethylene ether and sodium dodecyl benzene sulfonate are sequentially added to the reaction kettle, and the temperature is maintained at 50-55℃, and continuous stirring is performed to form a transparent solution;

[0060] Step S303, sodium polyacrylate is slowly poured into the transparent solution, and nano-silicon dioxide is added, the stirring speed is increased and continuous stirring is performed for 20 minutes to obtain a mixture;

[0061] Step S304, the mixture is transferred to a high-pressure homogenizer and processed for 2-3 cycles;

[0062] Step S305, the mixture after homogenization is sampled and detected pH, and the pH is adjusted to 8.8~9.2 with sodium hydroxide solution, and then it is filtered after being cooled to below 30℃, to obtain a new resin control agent.

[0063] In the above technical solution, the non-ionic surfactant is a fatty alcohol polyoxyethylene ether, the hydrophobic chain of the non-ionic surfactant can entangle the resin molecules, which can destroy the hydrogen bond network of the resin aggregate, and the hydrophobic modified surface of the hydrophobic silica adsorbent can preferentially adsorb the hydrophobic groups of the resin; the concentration of metal ions is first reduced and controlled by using a chelating agent, and then the resin dispersion efficiency is improved by using a surfactant to strip and anchor nanoparticles. The manufacturing steps have the characteristics of no phosphating, and the non-phosphating resin control surfactant has good stability and heat resistance in a high temperature environment, and can maintain its cleaning effect under high temperature conditions and is not easy to decompose.

[0064] Specifically, in steps S301~S303, a high-speed dispersion stirrer is used for stirring, which is an anchor type stirrer with a rotation speed of 0~1000rpm. The high-speed dispersion stirrer can control the stirring speed and stirring time, and achieve the purpose of fine mixing. In step S301, the preferred rotation speed of the high-speed dispersion stirrer is 200rpm, and the stirring time is preferably 10min; in step S302, the preferred rotation speed of the high-speed dispersion stirrer is 300rpm, and the stirring time is preferably 30min; in step S303, the rotation speed of the high-speed dispersion stirrer is increased to 500rpm, which is the best.

[0065] It should be noted that in step S301, the chelating agent is preferably EDTA disodium salt, which forms a stable complex with various metal ions, thereby hindering the catalytic effect of metal ions; in step S303, the sodium polyacrylate can be pre-wetted with a small amount of water, and then slowly added into the transparent solution to avoid caking; the particle size of the nano-silica is preferably 50nm; in step S304, the pressure of the high-pressure homogenizer is 50~100MPa, and the pressure is preferably 80MPa when processing the mixture, to ensure that the particle size is not greater than 200nm; in addition, the high-pressure homogenizer can be replaced by a high-shear emulsifier; in step S305, a 200-mesh stainless steel filter screen or a bag filter is selected for filtering the cooled mixture.

[0066] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A willow fir pulping process, characterized in that: It includes the following steps: Step S10, selecting qualified Chinese fir wood chips and bamboo raw materials, and pre-treating the Chinese fir wood chips and bamboo raw materials to obtain prepared materials; Step S20, placing the prepared material into a cooking pot, and steaming the prepared material using Valmet's batch cooking C-mode combined with steaming pre-impregnation mode to obtain a raw pulp; Step S30, screening, oxygen deoxidation, bleaching and multiple pulp washing processes are performed on the raw pulp, and a novel resin control agent is added to the raw pulp during deoxidation and pulp washing to obtain a finished pulp; Step S40: sending the finished pulp into a pulp storage tower for storage.

2. The willow fir pulping process according to claim 1, characterized in that: The qualified fir wood chips have a length of 20-30 mm, a width of 15-20 mm, a thickness of 3-5 mm, and a bulk density of 160-180 Bd kg / , the moisture content is 30%~60%; the qualified bamboo raw material has a length of 20~40mm, a width of 5~15mm, and a moisture content of 30%~50%.

3. The willow fir pulping process according to claim 1, characterized in that: The qualified Japanese cedar wood chips and bamboo raw materials are all mechanically peeled.

4. The willow fir pulping process according to claim 1, characterized in that: The pretreatment of the cryptomeria wood chips and bamboo raw materials comprises the following steps: Step S101: stack qualified Japanese cedar wood chips and bamboo raw materials into a silo and let them stand for 5 to 7 months; Step S102, transporting the cedar wood chips and bamboo raw materials after standing to a swing screen for screening to obtain cedar wood chips and bamboo raw materials of uniform size; Step S103: transporting the cedar wood chips and bamboo raw materials of uniform size to a washing machine for washing and dehydration to obtain prepared materials.

5. The willow fir pulping process according to claim 1, characterized in that: In step S20, an active chemical solution is added into the cooking pot, wherein the main components of the active chemical solution are sodium hydroxide, sodium sulfide and sodium sulfate.

6. The willow fir pulping process according to claim 1, characterized in that: In step S20, the cooking temperature of the prepared materials is controlled at 160-162° C., and the cooking time is controlled at 310-330 min.

7. The willow fir pulping process according to claim 1, characterized in that: In step S30, multiple washings of the raw pulp are completed using multiple twin-roll squeezers.

8. The willow fir pulping process according to claim 1, characterized in that: In step S30, the preparation of the novel resin control agent includes the following steps: Step S301, add deionized water to the reactor and heat it to 50°C; then add the chelating agent and stir until it is completely dissolved; Step S302, adding fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate to the reaction kettle in sequence, maintaining the temperature at 50-55° C., and continuously stirring to form a transparent solution; Step S303: slowly sprinkle sodium polyacrylate into the transparent solution, then add nano-silicon dioxide, increase the stirring speed and continue stirring for 20 minutes to obtain a mixture; Step S304: transfer the mixture to a high-pressure homogenizer and cycle the process 2 to 3 times; Step S305 , sampling the homogenized mixture and detecting the pH value, adjusting the pH value to 8.8-9.2 with sodium hydroxide solution, cooling the mixture to below 30° C., and filtering the mixture to obtain a novel resin control agent.

9. The willow fir pulping process according to claim 8, characterized in that: The steps S301 to S303 are all stirred using a high-speed disperser, and the high-speed disperser is an anchor type stirrer.

10. The willow fir pulping process according to claim 8, characterized in that: In the step S301, the chelating agent is EDTA disodium salt.

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