A method for preparing base pulp for household paper

Abstract

This invention belongs to the field of tissue paper production technology, and relates to a method for preparing tissue paper base pulp, comprising: S1, constructing an ultra-low brightness wood pulp supply system connected to the original tissue paper production system; S2, mixing ultra-low brightness wood pulp and the original wood pulp from the original tissue paper production system; S3, controlling the proportion of ultra-low brightness wood pulp to 0.2%-1.0% during mixing; S4, controlling the flow rate of ultra-low brightness wood pulp according to its concentration and the flow rate and concentration of the original wood pulp; S5, sending the mixed ultra-low brightness wood pulp and the original wood pulp to subsequent processes in the original tissue paper production system to produce tissue paper whose brightness and dust point meet national standards. The method of this invention enables the production of base paper using ultra-low brightness pulp boards that meets national standards for brightness and dust point.

Description

Technical Field

[0001] This invention belongs to the field of tissue paper production technology and relates to a method for preparing tissue paper base pulp. Background Technology

[0002] Currently, the brightness of mainstream commercial wood pulp is generally around 89%. After entering tissue paper factories, this wood pulp needs further pulping and blending processes, which will slightly increase the brightness of the pulp. However, the current national standard for tissue paper (including toilet paper, facial tissues, kitchen paper, hand towels, etc.) requires a D65 brightness (whiteness) of ≤90.0%. As mentioned earlier, because the original whiteness of ordinary commercial pulp boards is relatively high, generally around 89%, after tissue paper factories perform pulping and other processing, the whiteness of the pulp increases, which may result in the finished product having a whiteness that meets or exceeds the national standard requirements.

[0003] Currently, the common method to solve this problem is to purchase low-brightness commercial pulp boards and use them in combination with ordinary commercial pulp boards. This method can effectively reduce the whiteness of the product. However, the amount of low-brightness commercial pulp boards used is relatively large, and they contain a large number of dust particles, causing the dust particles in the finished tissue paper to exceed the national standard requirements, so it cannot be used in large quantities. The reason is that low-brightness commercial pulp boards contain a large number of small-sized dark brown impurities and a small number of impurities ≥2.0mm in size, which conventional tissue paper making systems cannot remove. Therefore, it is difficult to meet the national standards for both whiteness and dust particles when using low-brightness pulp boards in tissue paper production. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems and provide a method for preparing base pulp for household paper.

[0005] To achieve the above objectives, the present invention provides a method for preparing base pulp for household paper, comprising: S1. Construct a connection to the ultra-low brightness wood pulp supply system on the original tissue paper production system; S2. Mix the ultra-low brightness wood pulp with the original wood pulp from the original tissue paper production system; S3. During mixing, the proportion of ultra-low whiteness wood pulp should be controlled at 0.2%-1.0%; S4. Control the flow rate of ultra-low brightness wood pulp according to the concentration of ultra-low brightness wood pulp and the flow rate and concentration of the original wood pulp. S5. The mixed ultra-low whiteness wood pulp and original wood pulp are sent to the original tissue paper production system for subsequent processes to produce tissue paper that meets national standards in terms of whiteness and dust points.

[0006] Furthermore, the original tissue paper production system includes a connected original wood pulp tank, a pulp mixer, a pulp forming tank, and a papermaking section.

[0007] Furthermore, the ultra-low whiteness wood pulp supply system includes an ultra-low whiteness pulp crusher and a pulp pump connected in sequence, as well as a white water tank and a pulping water pump and a purification flushing pump respectively connected to the white water tank. The pulping water pump is connected to the ultra-low whiteness pulp crusher. The white water tank is connected to the purification flushing pump via a pipeline, and the slurry pump is connected to the pipeline.

[0008] Furthermore, the outlet of the purification slurry pump is connected to a purification pressure screen, which is connected to an ultra-low white slurry tank and a wastewater treatment and recovery device. The concentrated water produced by the purification pressure screen is sent to the wastewater treatment and recovery device, and the good slurry produced by the purification pressure screen is sent to the ultra-low white slurry tank.

[0009] Furthermore, the ultra-low white slurry tank is connected to an ultra-low white slurry mixing pump, which is connected to the mixer via a pipeline; The pipeline is equipped with an ultra-low white slurry flow meter and an ultra-low white slurry concentration meter.

[0010] Furthermore, the purification pressure screen is used to remove impurities with a length greater than 1 mm.

[0011] Furthermore, the ultra-low whiteness wood pulp has a whiteness of 43%-46%.

[0012] Furthermore, if the mixing ratio of the ultra-low white slurry mixing pump is D, the ultra-low white slurry mixing flow rate is Q1, the ultra-low white slurry mixing concentration is c1, the original mixing flow rate is Q2, and the original mixing concentration is c2, then the following condition is met: Q1 = Q2 × c2 × D ÷ c1.

[0013] The beneficial effects of the present invention are as follows: The method for preparing paper pulp for household use of the present invention can produce paper that meets the national standards for whiteness and dust points using ultra-low whiteness pulp boards. Attached Figure Description

[0014] Figure 1 The schematic diagram illustrates the process flow of the method for preparing paper pulp for household use according to the present invention; Figure 2 The diagram illustrates the ultra-low white pulp preparation system according to the present invention.

[0015] The numbers in the attached diagram represent the following: 1. Original wood pulp tank; 2. Pulp mixer; 3. Pulp forming tank; 4. Papermaking section; 5. Ultra-low white pulp crusher; 6. Pulp pump; 7. White water tank; 8. Pulp feed pump; 9. Purified pulp flushing pump; 10. Purified pressure screen; 11. Ultra-low white pulp tank; 12. Wastewater treatment and recycling equipment; 13. Ultra-low white pulp mixing pump; 14. Ultra-low white pulp flow meter; 15. Ultra-low white pulp concentration meter. Detailed Implementation

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0018] Combination Figure 1 and Figure 2 As shown, this invention provides a method for preparing base pulp for household paper, comprising: S1, constructing an ultra-low brightness wood pulp supply system connected to the original household paper production system; S2, mixing the ultra-low brightness wood pulp and the original wood pulp from the original household paper production system; S3, controlling the mixing ratio of ultra-low brightness wood pulp to 0.2%-1.0% during mixing; S4, controlling the flow rate of ultra-low brightness wood pulp according to the concentration of ultra-low brightness wood pulp and the flow rate and concentration of the original wood pulp; S5, sending the mixed ultra-low brightness wood pulp and the original wood pulp to subsequent processes in the original household paper production system to produce household paper whose brightness and dust point meet national standards. Wherein, the mixing ratio of the ultra-low brightness wood pulp mixing pump is D, the ultra-low brightness wood pulp mixing flow rate is Q1, the ultra-low brightness wood pulp mixing concentration is c1, the original pulp flow rate is Q2, and the original pulp concentration is c2, then satisfying: Q1=Q2×c2×D÷c1.

[0019] In this invention, the primary tissue paper production system includes a primary wood pulp tank 1, a mixing unit 2, a pulping tank 3, and a papermaking section 4 connected in series. The ultra-low brightness wood pulp supply system includes an ultra-low brightness pulp crusher 5 and a pulp pump 6 connected in sequence, and also includes a white water tank 7 and a pulping water supply pump 8 and a purification flushing pump 9, both connected to the white water tank 7. The pulping water supply pump 8 is connected to the ultra-low brightness pulp crusher 5, the white water tank 7 and the purification flushing pump 9 are connected via pipelines, and the pulp pump 6 is connected to a pipeline. The outlet of the purification flushing pump 9 is connected to a purification pressure screen 10, which is connected to an ultra-low brightness pulp tank 11 and a wastewater treatment and recovery device 12. The concentrated water produced by the purification pressure screen 10 is sent to the wastewater treatment and recovery device 12, and the good pulp from the purification pressure screen 10 is sent to the ultra-low brightness pulp tank 11. The ultra-low white slurry tank 11 is connected to an ultra-low white slurry mixing pump 13, which is connected to the mixer 2 via a pipeline. An ultra-low white slurry flow meter 14 and an ultra-low white slurry concentration meter 15 are respectively installed on the pipeline.

[0020] The present invention relates to a method for preparing base pulp for household paper, wherein the ultra-low whiteness wood pulp is a natural-colored pulp board with a white base of 43%-46%, and the pulp board contains a large number of impurities or dark brown fibers with a length ≥2mm and dust particles with a size ≤2mm.

[0021] The specific process of the method for preparing base pulp for household paper of the present invention is as follows: I. Preparation of ultra-low brightness wet pulp: The ultra-low brightness pulp board purchased from the factory is put into the ultra-low brightness pulp crusher 5. At the same time, a certain amount of white water in the white water tank 7 is pumped to the ultra-low brightness pulp crusher 5 through the pulp water supply pump 8 for pulp crushing. Ultra-low brightness wet pulp is obtained through crushing and stored in the ultra-low brightness pulp crusher 5 for later use. Purification of ultra-low brightness wet pulp: The purification flushing pump 9 is turned on to pump the white water in the white water tank 7 to the purification pressure screen 10. At the same time, the pulp pump 6 is turned on to pump the wet pulp stored in the ultra-low brightness pulp crusher 5 to the inlet of the purification flushing pump 9 to merge with the white water. The good pulp obtained by the purification pressure screen 10 is then introduced into the ultra-low brightness pulp tank 11. The concentrated water obtained is discharged to the wastewater treatment and recycling equipment 12. According to one embodiment of the present invention, the purification pressure screen 10 is used to remove impurities with a length greater than 1 mm.

[0022] III. Mixing of Ultra-Low Brightness Wet Pulp: Based on the brightness requirements of the produced base paper, the mixing ratio D of the ultra-low brightness pulp mixing pump is set. The program automatically calculates the required ultra-low brightness wet pulp mixing flow rate Q1 according to the formula Q1=Q2×c2×D÷c1, based on the original mixing flow rate Q2, the original mixing concentration c2, and the ultra-low brightness wet pulp mixing concentration c1 read by the ultra-low brightness pulp concentration meter 15. The ultra-low brightness pulp mixing pump 13 is then interlocked to stabilize the mixing flow rate at Q1, which can be monitored in real-time by the ultra-low brightness pulp flow meter 14. The ultra-low brightness pulp mixing pump 13 then pumps the ultra-low brightness pulp to the existing mixer 2 in the workshop, where it is mixed with the original wood pulp. The original wood pulp comes from the existing original wood pulp tank 1 in the workshop. According to one embodiment of the present invention, the original wood pulp tank can be a softwood pulp after-beating tank and / or a hardwood pulp after-beating tank, etc.

[0023] IV. Papermaking and Inspection: Papermaking and inspection refer to the production of household paper base paper using existing equipment and technology in each household paper production plant. The whiteness and dust point index of the base paper are obtained through inspection.

[0024] The following specific embodiments illustrate the method for preparing the base pulp for household paper of the present invention: Example 1: Production of household paper base paper with a whiteness of 89.0%.

[0025] (I) Preparation of ultra-low brightness wet pulp: The ultra-low brightness pulp board of a certain brand purchased by the factory, with a brightness of 45%, is put into the ultra-low brightness pulp crusher 5. At the same time, a certain amount of white water in the white water tank 7 is pumped to the ultra-low brightness pulp crusher 5 through the pulp water supply pump 8 for pulp crushing. Ultra-low brightness wet pulp is obtained through crushing and stored in the ultra-low brightness pulp crusher 5 for later use. (II) Purification of ultra-low whiteness wet pulp: The purification flushing pump 9 is turned on to pump the white water in the white water tank 7 to the purification pressure screen 10. At the same time, the pulp pump 6 is turned on to pump the wet pulp stored in the ultra-low whiteness pulp crusher 5 to the inlet of the purification flushing pump 9 to merge with the white water. The good pulp obtained by the purification pressure screen 10 is introduced into the ultra-low whiteness pulp tank 11 for storage. The concentrated water obtained is discharged to the original wastewater recycling point in the workshop. (III) Preparation of ultra-low whiteness wet pulp: According to the whiteness requirements of the produced base paper, the preparation ratio D of the ultra-low whiteness pulp preparation pump is set to 0.2%. The program automatically calculates the required ultra-low whiteness wet pulp preparation flow rate Q1 as 0.63 m³ / h based on the original preparation flow rate Q2 of 90 m³ / h, the original preparation concentration c2 of 3.5%, and the ultra-low whiteness wet pulp preparation concentration c1 of 1% read by the ultra-low whiteness pulp concentration meter, according to the formula Q1=Q2×c2×D÷c1. The ultra-low whiteness wet pulp preparation pump 13 is then controlled by interlock to stabilize the preparation flow rate to Q1 and pump the ultra-low whiteness pulp to the original mixer 2 in the workshop for mixing with the original pulp. (iv) Papermaking and Inspection: Papermaking and inspection refer to the papermaking of the raw paper for household paper production plants using their existing equipment and technology. The inspection results show that the whiteness of the raw paper is 88.94%, and the total number of dust particles is 1 / ㎡. Among them, the number of dust particles with a size of 0.2-1.0mm is 1 / ㎡, the number of dust particles with a size of 1.0-2.0mm is 0 / ㎡, and there are no dust particles >2.0mm. Both of the above indicators meet the requirements of all national standards for household paper.

[0026] Example 2: Production of household paper base paper with a whiteness of 88.5%.

[0027] (I) Preparation of ultra-low brightness wet pulp: The ultra-low brightness pulp board purchased from the factory, with a tested brightness of 45%, is put into the ultra-low brightness pulp crusher 5. At the same time, a certain amount of white water from the white water tank 7 is pumped to the ultra-low brightness pulp crusher 5 through the pulping water supply pump 8 for pulping. Ultra-low brightness wet pulp is obtained through crushing and stored in the ultra-low brightness pulp crusher 5 for later use. (II) Purification of ultra-low whiteness wet pulp: The purification flushing pump 9 is turned on to pump the white water in the white water tank 7 to the purification pressure screen 10. At the same time, the pulp pump 6 is turned on to pump the wet pulp stored in the ultra-low whiteness pulp crusher to the inlet of the purification flushing pump 9 to merge with the white water. The good pulp obtained by the purification pressure screen 10 is introduced into the ultra-low whiteness pulp tank 11 for storage. The concentrated water obtained is discharged to the original wastewater recycling point in the workshop. (III) Preparation of ultra-low whiteness wet pulp: According to the whiteness requirements of the produced base paper, the preparation ratio D of the ultra-low whiteness pulp preparation pump is set to 0.6%. The program automatically calculates the required ultra-low whiteness wet pulp preparation flow rate Q1 as 1.89 m³ / h based on the original preparation flow rate Q2 of 90 m³ / h, the original preparation concentration c2 of 3.5%, and the ultra-low whiteness wet pulp preparation concentration c1 read by the ultra-low whiteness pulp concentration meter as 1%, according to the formula Q1=Q2×c2×D÷c1. The ultra-low whiteness wet pulp preparation pump 13 is then controlled by interlock to stabilize the preparation flow rate to Q1, and the ultra-low whiteness pulp is pumped to the original mixer 2 in the workshop to be mixed with the original pulp. (iv) Papermaking and Inspection: Papermaking and inspection refers to the papermaking of the raw paper for household paper produced by each household paper production plant using its existing equipment and technology. The inspection results show that the whiteness of the raw paper is 88.43%, and the total number of dust particles is 2 / ㎡. Among them, the number of dust particles with a size of 0.2-1.0mm is 2 / ㎡, the number of dust particles with a size of 1.0-2.0mm is 0 / ㎡, and there are no dust particles >2.0mm. Both of the above indicators meet the requirements of all national standards for household paper.

[0028] Example 3: Production of household paper base paper with a whiteness of 88.0%.

[0029] (I) Preparation of ultra-low brightness wet pulp: The ultra-low brightness pulp board purchased from the factory, with a tested brightness of 45%, is put into the ultra-low brightness pulp crusher 5. At the same time, a certain amount of white water from the white water tank 7 is pumped to the ultra-low brightness pulp crusher 5 through the pulping water supply pump 8 for pulping. Ultra-low brightness wet pulp is obtained through crushing and stored in the ultra-low brightness pulp crusher 5 for later use. (II) Purification of ultra-low whiteness wet pulp: The purification flushing pump 9 is turned on to pump the white water in the white water tank 7 to the purification pressure screen 10. At the same time, the pulp pump 6 is turned on, and the wet pulp stored in the ultra-low whiteness pulp crusher is pumped to the inlet of the purification flushing pump 9 to merge with the white water. The good pulp obtained by the purification pressure screen 10 is introduced into the ultra-low whiteness pulp tank 11 for storage. The concentrated water obtained is discharged to the original wastewater recycling point in the workshop. (III) Preparation of ultra-low whiteness wet pulp: According to the whiteness requirements of the produced base paper, the preparation ratio D of the ultra-low whiteness pulp preparation pump is set to 1.0%. The program automatically calculates the required ultra-low whiteness wet pulp preparation flow rate Q1 as 3.15 m³ / h based on the original preparation flow rate Q2 of 90 m³ / h, the original preparation concentration c2 of 3.5%, and the ultra-low whiteness wet pulp preparation concentration c1 of 1% read by the ultra-low whiteness pulp concentration meter, according to the formula Q1=Q2×c2×D÷c1. The ultra-low whiteness wet pulp preparation pump 13 is then controlled by interlock to stabilize the preparation flow rate to Q1, and the ultra-low whiteness pulp is pumped to the original mixer 2 in the workshop to be mixed with the original pulp. (iv) Papermaking and Inspection: Papermaking and inspection refers to the papermaking of the raw paper for household paper produced by each household paper production plant using its existing equipment and technology. The inspection results show that the whiteness of the raw paper is 87.91%, and the total number of dust particles is 3 / ㎡. Among them, the number of dust particles with a size of 0.2-1.0mm is 3 / ㎡, the number of dust particles with a size of 1.0-2.0mm is 0 / ㎡, and there are no dust particles >2.0mm. Both of the above indicators meet the requirements of all national standards for household paper.

[0030] The method for preparing base paper pulp for household paper of the present invention can produce base paper that meets national standards for whiteness and dust point using ultra-low whiteness pulp boards. Furthermore, the process and operation are simple, and whiteness can be controlled in real time by fine-tuning the flow rate of the ultra-low whiteness pulp. The above description is merely one embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing base pulp for household paper, comprising: S1. Construct a connection to the ultra-low brightness wood pulp supply system on the original tissue paper production system; S2. Mix the ultra-low brightness wood pulp with the original wood pulp from the original tissue paper production system; S3. During mixing, the proportion of ultra-low whiteness wood pulp should be controlled at 0.2%-1.0%; S4. Control the flow rate of ultra-low brightness wood pulp based on the concentration of ultra-low brightness wood pulp and the flow rate and concentration of the original wood pulp. S5. The mixed ultra-low whiteness wood pulp and the original wood pulp are sent to the original tissue paper production system for subsequent processes to produce tissue paper that meets the national standards for whiteness and dust points. The ultra-low whiteness wood pulp supply system includes an ultra-low whiteness pulp crusher and a pulp pump connected in sequence, as well as a white water tank and a pulping water pump and a purification flushing pump respectively connected to the white water tank. The pulping water pump is connected to the ultra-low whiteness pulp crusher. The white water tank is connected to the purification flushing pump via a pipeline, the slurry pump is connected to the pipeline, and the outlet of the purification flushing pump is connected to a purification pressure screen. The ultra-low whiteness wood pulp has a whiteness of 43%-46%.

2. The method for preparing base pulp for household paper according to claim 1, characterized in that, The original household paper production system includes a connected original wood pulp tank, a mixing unit, a pulp forming tank, and a papermaking section.

3. The method for preparing base pulp for household paper according to claim 2, characterized in that, The purification pressure screen is connected to an ultra-low white slurry tank and a wastewater treatment and recovery device. The concentrated water produced by the purification pressure screen is sent to the wastewater treatment and recovery device, and the good slurry produced by the purification pressure screen is sent to the ultra-low white slurry tank.

4. The method for preparing base pulp for household paper according to claim 3, characterized in that, The ultra-low white slurry tank is connected to an ultra-low white slurry mixing pump, which is connected to the mixer via a pipeline. The pipeline is equipped with an ultra-low white slurry flow meter and an ultra-low white slurry concentration meter.

5. The method for preparing base pulp for household paper according to claim 4, characterized in that, The purification pressure screen is used to remove impurities with a length greater than 1 mm.

6. The method for preparing base pulp for household paper according to claim 5, characterized in that, The mixing ratio of the ultra-low white slurry mixing pump is D, the ultra-low white slurry mixing flow rate is Q1, the ultra-low white slurry mixing concentration is c1, the original mixing flow rate is Q2, and the original mixing concentration is c2. Then, the following condition is met: Q1 = Q2 × c2 × D ÷ c1.

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