An improved waste paper making system and method thereof

Abstract

The invention discloses an improved waste paper making method. According to the detection data such as PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, COD value, etc. collected by each monitoring end of an information collection device in a waste paper making system, after being summarized by a central processing device, a comprehensive analysis is conducted to determine whether each data exceeds the standard, and the start and stop of the addition of an auxiliary agent and the adjustment amount are automatically adjusted. By balancing the charge of the paper making system, anionic garbage is captured, and the temporary wet strength, ash retention rate, and first-pass retention rate of the paper are improved. Continuous production is carried out for one week without paper breakage or holes, thereby improving the paper production efficiency and saving the production cost and wastewater treatment cost at the same time.

Description

Technical Field

[0001] The invention belongs to the field of papermaking, and in particular relates to an improved waste paper making system and a paper making method thereof. Background Art

[0002] Polymers such as polyacrylamide are used in paper and board manufacturing to improve dewatering during the web formation process. The challenge in improving dewatering is good initial flocculation combined with a dense floc structure. Flocculation problems lead to reduced web quality, and floc structure problems reduce drainage in press dewatering, which increases drying requirements in the subsequent drying step and can therefore be a productivity limiting part of the paper machine.

[0003] In recent years, after the ban on the import of waste paper from the United States, the utilization rate of domestic waste paper has been greatly increased in China, especially in the field of packaging paper such as gray-bottom white board paper, corrugated paper, and boxboard paper. The proportion of domestic waste paper used is increasing. The raw materials for papermaking are mainly domestic waste paper, including white waste paper, book and magazine waste paper, old newsprint, carton and cardboard waste paper, paper bag paper waste paper, kraft paper waste paper, and mixed waste paper. The quality of domestic waste paper is relatively low, and the raw materials of straw pulp and wood pulp are mixed, resulting in a low raw material fiber component of waste paper, so the demand for cations and paper strength is high. Due to the adoption of a closed white water circulation system for domestic papermaking, these shortcomings are more obvious. The large-scale use of domestic waste paper has brought various troubles to the papermaking system of paper mills, such as: high anion garbage content in the system, difficulty in dehydration, low paper strength, easy paper breakage, etc. Another problem arises from this. When used waste paper pulp is used for papermaking, the amount of additives used increases. However, in the papermaking industry, the method of adding additives once is usually adopted, and the effect is not as obvious as expected. For example, simply increasing the dosage of polyacrylamide is not the best solution. Increasing the addition of high molecular weight polyacrylamide may eventually lead to excessive flocculation of the fiber raw material, which further reduces the pressing dehydration rate and causes poor paper forming, thereby reducing the productivity of the method and the strength of the produced paper.

[0004] Low molecular weight polymers with high charge density, alone or in combination with systems involving the use of cationic high molecular weight polyacrylamide, have been used to improve dewatering and pressing efficiency in the manufacture of certain paper products. However, these low molecular weight polymers are limited in their ability to provide the necessary degree of flocculation without increasing the polymer dosage, which may lead to excessive cationization in the paper or paperboard manufacturing process and thus increase foaming and other related risks. Two-component systems comprising low molecular weight polymers with high charge density and cationic high molecular weight polyacrylamide are known, but they are difficult to control and increase the complexity of the paper or paperboard manufacturing process. For example, the ash, starch, sizing or dissolved and colloidal substances therein also lead to an increase in the COD of papermaking wastewater, an increase in the burden of wastewater treatment, and the suspended matter not retained in the papermaking process is discarded as industrial waste, so there is also a problem of adverse effects on the environment.

[0005] Therefore, a new auxiliary agent composition and an optimized waste paper making system are needed to improve the production efficiency of waste paper making. Summary of the invention

[0006] The purpose of the present invention is to provide an improved waste paper making system and method based on the prior art, which can minimize or even eliminate the shortcomings of the prior art, improve the production efficiency of waste paper making, save production costs and wastewater treatment costs, and at the same time reduce the discharge of wastewater and waste, which is beneficial to environmental protection.

[0007] An improved waste paper making system comprises a paper machine pulp pool, a pulp pump, a multi-stage slag remover, a degasser, a low pulse pressure screen, a headbox, a white water pool under the screen, and a papermaking wastewater pool. The system is characterized in that an additive storage device and an additive precision dosing device are provided at the inlet and outlet of the pulp pump and the inlet and outlet of the low pulse pressure screen. The additive storage device adds additives through the additive precision dosing device. The additives mainly include one or more of cationic flocculants, cationic coagulants, cationic charge neutralizers, cationic polymers with lower molecular weight, copolymers of acrylamide and dimethylaminoethyl acrylate, and inorganic polymer flocculants. Parameters such as PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, COD value, etc. in the system are adjusted by adding additives.

[0008] The additive storage device is provided with a plurality of additive storage tanks, which are respectively connected to the inlet and outlet of the slurry pump and the inlet and outlet of the low pulse pressure screen via the additive precision dosing device. The additive storage tanks include a slurry adjustment additive storage tank, a degassing additive storage tank, a purification additive storage tank, and a retention additive storage tank. The slurry adjustment additive storage tank is connected to the inlet of the slurry pump via the additive precision dosing device, the degassing additive storage tank is connected to the outlet of the slurry pump via the additive precision dosing device, the purification additive storage tank is connected to the inlet of the low pulse pressure screen via the additive precision dosing device, and the retention additive storage tank is connected to the inlet or outlet of the low pulse pressure screen via the additive precision dosing device.

[0009] Preferably, the slurry adjusting aid in the slurry adjusting aid storage tank mainly includes cationic polyacrylamide, dimethyldiallyl polyammonium chloride, and polyaluminum chloride, and these can be used alone or in combination of two or more; the degassing aid in the degassing aid storage tank mainly includes cationic polyacrylamide and defoaming agent, and these can be used alone or in combination of two or more; the purification aid in the purification aid storage tank mainly includes cationic starch, cationic polyacrylamide, and dimethylaminoethyl acrylate, and these can be used alone or in combination of two or more; the retention aid in the retention aid storage tank mainly includes cationic polyacrylamide and micropolymers, and these can be used alone or in combination of two or more.

[0010] In the present invention, the micropolymer includes an organic microparticle retention aid, and the cationic papermaking retention aid produced by Suzhou Saiweko Environmental Protection Technology Service Co., Ltd. is adopted.

[0011] In the present invention, all raw materials used can be obtained by commercial purchase and / or preparation by means of preparation, and unless otherwise specified, all meet the requirements of standardized products.

[0012] The waste paper making system of the present invention further comprises an information collection device and a central processing device, wherein the information collection device comprises one or more of a charge measurement probe, a pulp concentration detection probe, a dynamic water filtration detection probe, a COD detection probe, and a paper ash sensor, and the monitoring ends of the information collection device are respectively arranged at the inlet and outlet of the pulping pump, the inlet and outlet of the low pulse pressure screen, the white water pool under the net, and the papermaking wastewater pool, the information collection device is connected to the central processing device through a line, and the additive precision dosing device is connected to the central processing device through a line;

[0013] According to Chinese invention patent application 202110816795.3, a real-time microbial detection and control device for a paper machine making system and a warning and control method, the present invention may further include a cloud platform real-time comprehensive data analysis and feedback device that is connected to a central processing unit and is capable of performing real-time data analysis and realizing control functions. The cloud platform real-time comprehensive data analysis and feedback device has the functions of cloud computing and big data analysis, and can quickly utilize various functions such as various networks, storage, and services with less investment, and use massive amounts of data to make rapid judgments and analyses, and can promptly feed back accurate results to the central processing unit for operation. The information collection device can be connected to the central processing unit through a data communication network, and the data communication network includes limited communication and wireless communication, wherein the wireless communication methods include but are not limited to 4G, 5G, or Bluetooth.

[0014] The data detected by each information collection device include PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value. Among them, the PCD potential range is -1000~20μeq / l, the first-pass retention rate range is 65%~85%, the ash retention rate range is 45%~55%, the ash content range is 10%~20%, the freeness range is 400~500ml, and the COD value range is 500~3000mg / l. When the comprehensive analysis of PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value data exceeds the standard, the relevant additive addition amount is automatically fine-tuned, and when each detection data returns to the range, the additive addition amount is stopped.

[0015] According to Chinese invention patent application 202110816795.3, real-time microbial detection and control device and early warning and control method for paper machine papermaking system, the present invention can also adopt a monitoring method of early warning value, the range of early warning value is 10% to 20% of the difference between the upper limit of the big data range value and the lower limit of the big data range value, preferably 15%, and the direction of data change is the theoretical change trend of the detection parameter when the total amount of suspended matter (ss) in the system increases. The monitoring method using early warning value can proactively regulate the balance of charge in the system and avoid the delay of adding additives after paper breaks, pinholes, etc.

[0016] For example, the PCD potential range is -1000 to 20ueq / l. When the total amount of suspended solids (ss) in the system increases, the cation demand in the system increases and the first-pass retention rate decreases. Therefore, the data change direction of the first-pass retention rate is toward its lower limit value. The warning value is 10% to 20% of the difference between the lower limit of the first-pass retention rate range, that is, -902 to -804ueq / l, and preferably 15%, that is, -853ueq / l.

[0017] For example, the first-pass retention rate ranges from 65% to 85%. When the total amount of suspended solids (ss) in the system increases, the cation demand in the system increases and the PCD potential decreases. Therefore, the data change direction of the PCD potential is toward its lower limit value. The warning value is 10% to 20% of the difference between the lower limit of the PCD potential range, that is, 67% to 69%, and preferably 15%, that is, 68%.

[0018] The dosage of the additive can be adjusted appropriately according to the total amount of suspended solids (ss), etc. The general dosage is 100-2000ppm, of which the dosage of pulping additive is 50-300ppm, the dosage of degassing additive is 50-250ppm, the dosage of purification additive is 50-400ppm, and the dosage of retention additive is 100-800ppm; the daily dosage time of the additive is 0-1440min. If the dosage is less than 50ppm, the flocculation effect will be reduced, and the charge in the system cannot be balanced. If the dosage is greater than 2000ppm, it will cause over-cationization, thereby affecting the addition effect of papermaking retention and filtration aids and affecting paper formation.

[0019] The present invention provides a method for waste paper making using the waste paper making system, comprising the following steps:

[0020] Step a, using a pulp pump to adjust and dilute the pulp slurry;

[0021] Step b, using a multi-stage cleaner to remove impurities with higher density in the pulp slurry;

[0022] Step c, removing free air from the pulp slurry using a deaerator;

[0023] Step d, using a low pulse pressure screen to remove flocs and fiber bundles from the pulp slurry;

[0024] Step e, the pulp slurry enters the wire section for papermaking through a headbox;

[0025] The technical solution of the present invention further includes step a0 before step a, adding a slurry adjusting agent; step b1 between steps b and c, adding a degassing agent; step c1 between steps c and d, adding a purification agent to reduce the cation demand on the fiber surface, reduce the generation of fiber bundles, and further flocculate the degassed fine fibers; and step d1 between steps d and e, adding a retention agent.

[0026] The technical solution of the present invention is mainly used for the papermaking process of high percentage waste paper pulp, and adopts papermaking raw materials of waste paper pulp of not less than 70% by mass for papermaking, and the papermaking raw materials are mainly domestic waste paper, including white waste paper, book and magazine waste paper, old newsprint, carton and cardboard waste paper, paper bag paper waste paper and kraft paper waste paper, and mixed waste paper. Domestic waste paper raw materials are mixed with straw pulp and wood pulp, resulting in low raw material fiber content of waste paper, so the demand for cations and the temporary wet strength of paper are relatively high, and the waste paper raw materials need to be decomposed, dusted, deinked, bleached, washed, dehydrated and other processes to make waste paper pulp.

[0027] The technical solution of the present invention adopts the idea of ​​stratified treatment of the cation demand in the system, firstly adding a pulping agent to preliminarily neutralize the pulp slurry and flocculate the anionic garbage with a larger density; then adding a degassing agent to further neutralize the pulp slurry, so that the anionic garbage with a smaller density is dispersed and fixed on the pulp fibers, and at the same time assisting the degassing of the pulp slurry, through the physical and chemical combination, small bubbles are aggregated to form large bubbles, and then burst, which can not only suppress the defects of paper breaks and pinholes in the paper sheet, but also reduce the combination of fine fibers and bubbles, thereby improving The subsequent pulp retention effect is good and easy to disperse; then add purification additives to reduce the cation demand on the fiber surface and reduce the generation of fiber bundles. At the same time, the free fine fibers after degassing are further flocculated and fixed to avoid the subsequent fine fibers from adsorbing a large amount of retention additives, thereby improving the screening effect and dehydration effect and paper strength; finally, add retention additives, use organic polymer retention agents with weaker cations, fine-tune the balance of cation demand in the system, and at the same time improve the dispersibility of flocculation groups and the retention rate and uniformity of fine fibers and fillers in the pulp when they are put on the screen.

[0028] The waste paper making system of the present invention can be used to produce various medium and high-grade printing papers, newsprint, book cover paper, dictionary paper, cardboard, paperboard, etc. The paper weight range is 40-800g / m 2 .

[0029] Adopt the technical scheme of the present invention, the advantages are as follows:

[0030] The present invention detects parameters such as PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, COD value, etc. in the system parts, feeds back to the central processing device, analyzes through the central processing unit, and automatically adjusts the start and stop of the addition of auxiliary agents and the adjustment amount, balances the charge of the papermaking system, captures anionic garbage, enhances the papermaking dehydration performance, improves the temporary wet strength, dry strength, ash retention rate, and first-pass retention rate of the finished paper, and has almost no paper breaks and holes in continuous production for one week, thereby improving paper production efficiency; due to the improvement of the ash retention rate and the first-pass retention rate, the concentration of papermaking raw materials, chemical reagents and other dissolved organic matter in the wastewater discharged from the papermaking process is reduced, the COD of the wastewater is reduced, the generation of slime in the papermaking system is suppressed, the number of shutdowns for cleaning is greatly reduced, the continuous operation time is extended, the production cost and the wastewater treatment cost are saved, and the discharge of wastewater and waste is reduced, which is beneficial to environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of a waste paper making system.

[0032] Figure 2 Schematic diagram of the process of waste paper making system.

[0033] Among them, 1-slurry mixing additive storage tank, 2-degassing additive storage tank, 3-purification additive storage tank, 4-retention additive storage tank, 5-additive precision dosing device. DETAILED DESCRIPTION

[0034] The improved waste paper making method of the present invention is further described by the following examples, but these examples do not constitute any limitation to the present invention.

[0035] An improved waste paper making system, comprising a paper machine pulp pool, a pulp pump, a multi-stage slag remover, a degasser, a low pulse pressure screen, a headbox, a white water pool under the screen, and a papermaking wastewater pool, characterized in that it also comprises an information collection device, a central processing device, an additive storage device and an additive precision dosing device 5, the information collection device comprises one or more of a charge measurement probe, a pulp concentration detection probe, a dynamic water filtration detection probe, a COD detection probe, and a paper ash sensor, and the monitoring ends of the information collection device are respectively arranged at the inlet and outlet of the pulp pump, the inlet of the low pulse pressure screen, and the outlet of the pulp pump. In the inlet and outlet, the white water pool under the screen, and the papermaking wastewater pool, the inlet and outlet of the pulping pump, the inlet and outlet of the low pulse pressure screen, the white water pool under the screen, and the papermaking wastewater pool are provided with an additive storage device and an additive precision dosing device 5, the information collection device is connected to the central processing device through a line, the additive storage device is provided with a plurality of additive storage tanks, which are respectively connected to the inlet and outlet of the pulping pump, the inlet and outlet of the low pulse pressure screen through the additive precision dosing device 5, and the additive precision dosing device 5 is connected to the central processing device through a line;

[0036] The auxiliary agent storage tanks include a slurry mixing auxiliary agent storage tank 1, a degassing auxiliary agent storage tank 2, a purification auxiliary agent storage tank 3, and a retention auxiliary agent storage tank 4. The auxiliary agents mainly include one or more of cationic flocculants, cationic coagulants, cationic charge neutralizers, cationic polymers with lower molecular weight, copolymers of acrylamide and dimethylaminoethyl acrylate, and inorganic polymer flocculants.

[0037] The sizing aid in the sizing aid storage tank 1 is mainly composed of cationic polyacrylamide, dimethyldiallyl polyammonium chloride, and polyaluminum chloride. The degassing aid in the degassing aid storage tank 2 is mainly composed of cationic polyacrylamide and a defoaming agent. The purification aid in the purification aid storage tank 3 is mainly composed of cationic starch, cationic polyacrylamide, and dimethylaminoethyl acrylate. The retention aid in the retention aid storage tank 4 is mainly composed of cationic polyacrylamide and a micropolymer.

[0038] The slurry mixing agent storage tank 1 in the present invention is connected to the inlet of the slurry pump via the precise additive dosing device 5, the degassing agent storage tank 2 is connected to the outlet of the slurry pump via the precise additive dosing device 5, the purification agent storage tank 3 is connected to the inlet of the low pulse pressure screen via the precise additive dosing device 5, and the retention agent storage tank 4 is connected to the inlet or outlet of the low pulse pressure screen via the precise additive dosing device 5.

[0039] The data detected by each information collection device include PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value. Among them, the PCD potential range is -1000~20ueq / l, the first-pass retention rate range is 65%~85%, the ash retention rate range is 45%~55%, the ash content range is 10%~20%, the freeness range is 400~500ml, and the COD value range is 500~3000mg / l. When the comprehensive analysis of PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value data exceeds the standard, additives are automatically added, and when each test data returns to the range, the addition of additives is stopped.

[0040] The general dosage of additives is 100-2000ppm, of which the dosage of slurry adjustment additives is 50-300ppm, the dosage of degassing additives is 50-250ppm, the dosage of purification additives is 50-400ppm, and the dosage of retention additives is 100-800ppm; the daily dosage time of additives is 0-1440min.

[0041] Example 1

[0042] according to Figure 1 As shown in the flowchart, the present invention provides a method for waste paper making using a waste paper making system, comprising the following steps:

[0043] Step a, using a pulp pump to adjust and dilute the pulp slurry;

[0044] Step b, using a multi-stage cleaner to remove impurities with higher density in the pulp slurry;

[0045] Step c, removing free air from the pulp slurry using a deaerator;

[0046] Step d, using a low pulse pressure screen to remove flocs and fiber bundles from the pulp slurry;

[0047] Step e, the pulp slurry enters the wire section for papermaking through a headbox;

[0048] Before step a, the method further includes step a0, adding a slurry adjusting agent; between steps b and c, the method further includes step b1, adding a degassing agent; between steps c and d, the method further includes step c1, adding a purification agent to reduce the cation demand on the fiber surface, reduce the generation of fiber bundles, and further flocculate the degassed fine fibers; between steps d and e, the method further includes step d1, adding a retention agent.

[0049] The dosage of cationic polyacrylamide, dimethyldiallyl polyammonium chloride and polyaluminium chloride in the slurry mixing additives is 50ppm;

[0050] The dosage of cationic polyacrylamide and defoamer in the degassing agent is 50ppm;

[0051] The dosage of cationic polyacrylamide, dimethylaminoethyl acrylate and cationic starch in the purification aid is 50ppm;

[0052] The dosage of cationic polyacrylamide and micropolymer in the retention aid is 100ppm;

[0053] Embodiments 2 to 7

[0054] Table 1 shows the specifications of each example. Except for the data shown in Table 1, the rest is the same as Example 1. Among them, Example 4 does not add a slurry adjustment agent, Example 5 does not add a degassing agent, Example 6 does not add a purification agent, and Example 7 does not add a retention agent.

[0055] Comparative Examples 1 to 4

[0056] The specifications of Comparative Example 1 are shown in Table 1, except for the different dosage, the rest are the same as Example 2;

[0057] In Comparative Example 2, only cationic polyacrylamide is used as the auxiliary agent, and the rest is the same as in Example 2;

[0058] In Comparative Example 3, all additives were added at the inlet of the slurry pump, and the rest was the same as in Example 2;

[0059] In Comparative Example 4, no auxiliary agent was added.

[0060] Example 8

[0061] Taking white waste paper as the waste paper raw material for the production of printing paper as an example, according to the PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, COD value and other detection data collected by each monitoring end of the information collection device in the waste paper making system, after being summarized by the central processing device, when the comprehensive analysis of each data exceeds the standard, additives are added according to the specifications in Examples 1 to 7 and Comparative Examples 1 to 4. When each detection data returns to the range, the addition of additives is stopped, and the papermaking situation of the system after the addition of additives is analyzed.

[0062]

[0063] As can be seen from Table 1, the present invention optimizes the waste paper making system by comprehensively using slurry mixing aids, degassing aids, purification aids and retention aids. According to the detection data such as PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, COD value, etc. collected by each monitoring end of the information collection device in the waste paper making system, after being summarized by the central processing device, a comprehensive analysis is made on whether each data exceeds the standard, and the additives are added to balance the charge in the paper making system, capture the anionic garbage in the system, improve the dehydration of paper, thereby improving the ash retention rate, first-pass retention rate, and temporary wet strength of the finished paper. There is almost no paper breakage and holes in continuous production for a week, which greatly reduces the number of shutdowns for cleaning. The paper production efficiency is improved; compared with Example 2, Comparative Example 1 uses excessive additives, resulting in over-cationization of the system, thereby affecting the effect of adding subsequent papermaking retention and filtration aids, and affecting paper forming; compared with Example 2, Comparative Example 2 only uses a single cationic polyacrylamide, and the flocculation and charge neutralization effects are slightly weaker than the formulas of Examples 1 to 3; compared with Example 2, all additives in Comparative Example 3 are added at the inlet of the pulping pump. Due to the large demand for anionic garbage cations in the system here, a large amount of degassing additives, purification additives, and retention additives are adsorbed, which affects the subsequent degassing, screening, and retention effects, thereby affecting paper forming.

[0064] Example 9

[0065] White waste paper is used as the waste paper raw material to produce printing paper and paperboard. According to the PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, COD value and other detection data collected by each monitoring end of the information collection device in the waste paper making system, after being summarized by the central processing device, each data is comprehensively analyzed. When the data exceeds the standard, the additive is added according to the specifications in Example 2. After 60 minutes of adding the additive, the paper machine and the paperboard machine are made, pressed and dehydrated, and dried to obtain paper or paperboard, and the obtained paper or paperboard is tested. Among them, the additive is added according to the specifications in Comparative Example 1 in Comparative Example 5; the additive is added according to the specifications in Comparative Example 2 in Comparative Example 6; the additive is added according to the specifications in Comparative Example 3 in Comparative Example 7; and the additive is added according to the specifications in Comparative Example 4 in Comparative Example 8. The tensile index and bursting index of paper and paperboard are measured according to the national standards GB / T 12914-2008 and GB / T 454-2002, respectively.

[0066] Table 2

[0067]

[0068]

[0069] Wet tensile strength: tested using PN-HT300F wet tensile strength tester in accordance with GB / T 24328.4-2020.

[0070] In order to ensure the quality of paper prepared by the waste paper making system of the present invention, the range of each test data is: PCD potential range is -1000~20μeq / l, first pass retention rate range is 65%~85%, ash retention rate range is 45%~55%, ash content range is 10%~20%, freeness range is 400~500ml, COD value range is 500~3000mg / l. When the comprehensive analysis of the test data such as PCD potential, first pass retention rate, ash retention rate, ash content, freeness, COD value, etc. of a part of the system exceeds the standard, the corresponding additive is automatically added, and when each test data is restored to the range, the adjustment of the additive addition amount is stopped. The reaction time after the addition of the additive is 5-60min.

[0071] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An improved waste paper making system, It is characterized in that The invention comprises a paper machine pulp pool, a pulp pump, a multi-stage slag remover, a degasser, a low pulse pressure screen, a headbox, a white water pool under the screen, and a papermaking wastewater pool. The invention is characterized in that an additive storage device and an additive precision dosing device are arranged at the inlet and outlet of the pulp pump and the inlet and outlet of the low pulse pressure screen, and the additive storage device adds additives through the additive precision dosing device. The additive storage device is provided with a plurality of additive storage tanks, and the additive storage tanks include a slurry mixing additive storage tank, a degassing additive storage tank, a purification additive storage tank and a retention additive storage tank. The slurry mixing additive storage tank is connected to the inlet of the slurry pump via the additive precision dosing device, the degassing additive storage tank is connected to the outlet of the slurry pump via the additive precision dosing device, the purification additive storage tank is connected to the inlet of the low pulse pressure screen via the additive precision dosing device, and the retention additive storage tank is connected to the inlet or outlet of the low pulse pressure screen via the additive precision dosing device; The slurry-adjusting agent in the slurry-adjusting agent storage tank mainly includes cationic polyacrylamide, dimethyldiallyl polyammonium chloride and polyaluminium chloride, the degassing agent in the degassing agent storage tank mainly includes cationic polyacrylamide and defoaming agent, the purification agent in the purification agent storage tank mainly includes cationic starch, cationic polyacrylamide and dimethylaminoethyl acrylate, and the retention agent in the retention agent storage tank mainly includes cationic polyacrylamide and micropolymer; The system also includes an information collection device and a central processing device. The information collection device includes a charge measurement probe, a pulp concentration detection probe, a dynamic water filtration detection probe, a COD detection probe and a paper ash sensor. The monitoring ends of the information collection device are respectively arranged at the inlet and outlet of the pulping pump, the inlet and outlet of the low pulse pressure screen, the white water pool under the net, and the papermaking wastewater pool. The information collection device is connected to the central processing device through a line, and the additive precision dosing device is connected to the central processing device through a line; The data detected by the information collection device include PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value; wherein the PCD potential ranges from -1000 to 20μeq / l, the first-pass retention rate ranges from 65% to 85%, the ash retention rate ranges from 45% to 55%, the ash content ranges from 10% to 20%, the freeness ranges from 400 to 500ml, and the COD value ranges from 500 to 3000mg / l; when the comprehensive analysis of the PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value data exceeds the standard, the amount of additive added is automatically fine-tuned, and when each detection data returns to within the range, the adjustment of the additive is stopped.

2. A method for making waste paper using the waste paper making system according to claim 1, The following steps are involved: Step a, using a pulp pump to adjust and dilute the pulp slurry; Step b, using a multi-stage cleaner to remove impurities with higher density in the pulp slurry; Step c, removing free air from the pulp slurry using a deaerator; Step d, using a low pulse pressure screen to remove flocs and fiber bundles from the pulp slurry; Step e, the pulp slurry enters the wire section for papermaking through a headbox; The method is characterized in that, before step a, step a0 is included, adding a slurry adjusting agent; between steps b and c, step b1 is included, adding a degassing agent; between steps c and d, step c1 is included, adding a purification agent to reduce the cation demand on the fiber surface, reduce the generation of fiber bundles, and flocculate the degassed fine fibers; and between steps d and e, step d1 is included, adding a retention agent.

3. The method for making waste paper according to claim 2, It is characterized in that According to the PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value detection data collected by each monitoring end of the information collection device in the waste paper making system, after being summarized by the central processing device, a comprehensive analysis is made to see whether each data exceeds the standard, and the addition and stop of the additives and the adjustment dosage are automatically adjusted.

4. The method for making waste paper according to claim 2, It is characterized in that The data detected by the information collection device include PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value; wherein the PCD potential ranges from -1000 to 20μeq / l, the first-pass retention rate ranges from 65% to 85%, the ash retention rate ranges from 45% to 55%, the ash content ranges from 10% to 20%, the freeness ranges from 400 to 500ml, and the COD value ranges from 500 to 3000mg / l; when the comprehensive analysis of the PCD potential, first-pass retention rate, ash retention rate, ash content, freeness, and COD value data exceeds the standard, the amount of additive added is automatically fine-tuned, and when each detection data returns to within the range, the adjustment of the additive is stopped.

5. The method for making waste paper according to claim 4, It is characterized in that The dosage of additives is 100~2000ppm, of which the dosage of slurry adjustment additives is 50~300ppm, the dosage of degassing additives is 50~250ppm, the dosage of purification additives is 50~400ppm, and the dosage of retention additives is 100~800ppm; the daily dosage time of additives is 0-1440min.

6. The method for making waste paper according to claim 2, It is characterized in that Papermaking adopts waste paper pulp of not less than 70% by mass, and the papermaking raw materials are mainly domestic waste paper, including white waste paper, book and magazine waste paper, old newsprint, carton and cardboard waste paper, paper bag paper waste paper and kraft paper waste paper and mixed waste paper; the paper breaking frequency of the paper is 0 to 12 times / week, and the wet tensile index of the finished paper is not less than 4Nm / g.

7. The method for making waste paper according to claim 2, It is characterized in that The finished paper produced by the waste paper making system is used to produce various medium and high-grade printing papers, newsprint, book cover paper, dictionary paper, cardboard or paperboard.

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