Treatment system and treatment method for wood chips for papermaking

Abstract

The invention provides a treatment system and a treatment method for wood chips for papermaking. The treatment system comprises a wood chip storage bin, a wood chip washing machine, a dehydrator, a conveying screw, an extrusion tearing machine, a presoaking device and a reaction bin which are sequentially connected in series. The treatment system further comprises a bypass spiral, the two ends of the bypass spiral are connected with the conveying spiral and the reaction bin respectively, and under the specific working condition, the bypass spiral can directly convey wood chips to the reaction bin from the conveying spiral. According to the treatment system for the wood chips for papermaking, provided by the embodiment of the invention, the whole-line shutdown caused by faults of key equipment such as an extrusion tearing machine and a presoaking device can be prevented, the shutdown yield waste caused by periodic maintenance of the equipment (such as the extrusion tearing machine), screen frame replacement, spiral replacement and presoaking device maintenance in the technological process is reduced, and the production efficiency is improved. The starting efficiency of the whole production line is improved, and the production and operation cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of papermaking, and in particular to a processing system and method for wood chips for papermaking. Background Art

[0002] The conventional technical solution for processing wood chips for papermaking is generally a single-line series layout of equipment. This means that once a device in the production line fails or is shut down for maintenance, the entire production line needs to be shut down, seriously affecting production efficiency. Summary of the invention

[0003] A first aspect of an embodiment of the present application provides a system for processing wood chips for papermaking, the processing system comprising: a wood chip storage bin, a wood chip washing machine, a dehydrator, a conveying screw, an extrusion tearing machine, a prepreg device and a reaction bin arranged in series in sequence; wherein, the processing system also includes a bypass screw, the two ends of which are respectively connected to the conveying screw and the reaction bin, and under specific working conditions, the bypass screw can transfer the wood chips directly from the conveying screw to the reaction bin.

[0004] In some embodiments, the processing system further comprises a drug adding device, which is connected to the conveying screw and adds drugs to the conveying screw position.

[0005] In some embodiments, a control valve is provided between the dosing device and the conveying screw.

[0006] In some embodiments, the processing system further comprises a prepreg feeding screw, wherein the prepreg feeding screw is connected in series between the conveying screw and the extrusion tearing machine.

[0007] In some embodiments, the processing system further comprises a discharge screw assembly, which is serially connected to the reaction bin and is used for discharging the reacted wood chips in the reaction bin.

[0008] In some embodiments, the unloading spiral group includes a reaction chamber unloading spiral and a plurality of horizontal transfer spirals connected in series.

[0009] In a second aspect, an embodiment of the present application provides a method for processing wood chips for papermaking, wherein the processing method uses the processing system described in the above embodiment to process wood chips for papermaking.

[0010] In some embodiments, the method includes: determining whether the bypass screw load is higher than a preset ratio of the unloading screw group load; if so, closing the bypass screw.

[0011] In some embodiments, the preset ratio is 70%.

[0012] In some embodiments, it includes: determining whether the material level in the reaction bin is higher than a preset material level, and if so, closing the bypass screw.

[0013] The wood chip processing system for papermaking provided in the embodiment of the present application adds a bypass spiral above the extrusion tearing machine and the prepreg. Under specific working conditions, the wood chips can be directly transported to the reaction chamber by the bypass spiral without passing through the extrusion tearing machine and the prepreg. This can prevent the entire line from being shut down due to failures of key equipment such as the extrusion tearing machine and the prepreg, reduce the waste of production caused by shutdowns due to periodic maintenance of equipment (such as the extrusion tearing machine) in the process flow, replacement of screen frames, spiral replacement, and maintenance of prepregs, improve the startup efficiency of the entire production line, and reduce production operation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 It is a structural schematic diagram of a wood chip processing system for papermaking in a conventional technical solution;

[0016] Figure 2 It is a schematic flow chart of an embodiment of a system for processing wood chips for papermaking of the present application;

[0017] Figure 3 It is a schematic flow chart of another embodiment of the processing system of wood chips for papermaking of the present application;

[0018] Figure 4 It is a flow chart of another embodiment of the processing system of wood chips for papermaking of the present application;

[0019] Figure 5 It is a schematic flow chart of another embodiment of the processing system of wood chips for papermaking of the present application;

[0020] Figure 6 It is a flow chart of another embodiment of the system for processing wood chips for papermaking of the present application. DETAILED DESCRIPTION

[0021] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0022] The terms "first", "second", and "third" in the embodiments of the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", and "third" can expressly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. The terms "including" and "having" in the embodiments of the present application and any of their variations are intended to cover non-exclusive inclusions. 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 optionally also includes steps or units that are not listed, or optionally also includes other steps or components inherent to these processes, methods, products, or devices.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] See also Figure 1 , Figure 1 It is a structural schematic diagram of a wood chip processing system for papermaking in a conventional technical solution, wherein the processing system includes a wood chip storage bin 100a, a wood chip washer 100b, a dehydrator 100c, a conveying screw 100d, an extrusion tearing machine 100e, a prepreg 100f, a reaction bin 100g, a discharge screw group 100h and a rear section 100i arranged in series, wherein a dosing device 100j adds medicine at the position of the prepreg 100f.

[0025] The above scheme has the following main defects:

[0026] ① Once a key equipment failure occurs in the existing process, such as failure of the extrusion tearing machine (hereinafter referred to as MSD) or the prepreg, the entire line will be shut down.

[0027] ② The load operation of the conveying screw is not interlocked with the wood chip unloading group, which poses a risk of blockage.

[0028] ③The wood chip unloading group is not involved in the dosing control, and the dosage cannot be dynamically adjusted according to the operating conditions.

[0029] ④ The periodic maintenance of MSD equipment, replacement of screen frames, and maintenance of prepregs during the process resulted in the inability to start the production line normally, causing a large amount of production capacity waste, affecting the startup efficiency and production operation costs of the entire production line.

[0030] ⑤ MSD, a key equipment in the process, needs to replace the spiral every 8 months, which requires at least 3 days of downtime; the screen frame needs to be replaced every 4 months, which requires 32 hours of downtime each time, seriously affecting production capacity.

[0031] ⑥ When producing low-whiteness slurry, the demand for chemicals is greatly reduced, and the prepreg can meet production needs without starting up. The existing process cannot be switched according to product type.

[0032] ⑦ The key equipment in the process, such as MSD gearbox, spiral and screen frame, needs to be replaced periodically under heavy-load continuous production. Replacing a gearbox requires at least 3 days of downtime, which seriously affects production capacity.

[0033] ⑧MSD reducer repair, screw replacement, and screen frame replacement take a long time, resulting in high maintenance costs.

[0034] In view of this, the present application embodiment provides a system for processing wood chips for papermaking, please refer to Figure 2 , Figure 2 It is a flow diagram of an embodiment of a processing system for wood chips for papermaking of the present application, and the processing system includes: a wood chip storage bin 101, a wood chip washer 102, a dehydrator 103, a conveying screw 104, an extrusion tearing machine 105, a prepreg 106 and a reaction bin 107 which are arranged in series in sequence; wherein, the processing system also includes a bypass screw 108, and both ends of the bypass screw 108 are respectively connected to the conveying screw 104 and the reaction bin 107. Under specific working conditions, the wood chips do not pass through the extrusion tearing machine 105 and the (vertical) prepreg 106, but the bypass screw 108 can directly transfer the wood chips from the conveying screw 104 to the reaction bin 107.

[0035] The wood chip processing system for papermaking provided in the present embodiment adds a bypass screw above the extrusion tearing machine and the prepreg. Under specific working conditions, the wood chips can be directly transported to the reaction chamber by the bypass screw without passing through the extrusion tearing machine and the prepreg. This can prevent the entire line from being shut down due to failures of key equipment such as the extrusion tearing machine and the prepreg, reduce the waste of production caused by shutdowns due to periodic maintenance of equipment (such as the extrusion tearing machine) in the process flow, replacement of screen frames, screw replacement, and maintenance of prepregs, improve the startup efficiency of the entire production line, and reduce production operation costs.

[0036] See also Figure 3 , Figure 3It is a flow chart of another embodiment of the processing system of wood chips for papermaking of the present application, and the processing system includes: a wood chip storage bin 101, a wood chip washing machine 102, a dehydrator 103, a conveying screw 104, an extrusion tearing machine 105, a prepreg 106 and a reaction bin 107 which are arranged in series in sequence; wherein, the processing system also includes a bypass screw 108, and both ends of the bypass screw 108 are respectively connected to the conveying screw 104 and the reaction bin 107. Under specific working conditions, the wood chips do not pass through the extrusion tearing machine 105 and the (vertical) prepreg 106, but the bypass screw 108 can directly transfer the wood chips from the conveying screw 104 to the reaction bin 107.

[0037] Different from the above-mentioned embodiment, the processing system in this embodiment further includes a dosing device 109, which is connected to the conveying screw 104 and adds drugs to the position of the conveying screw 104. Optionally, a control valve 110 is provided between the dosing device 109 and the conveying screw 104, and the control valve 110 can be a manual valve. The processing system in this embodiment can improve the bleaching efficiency by changing the dosing position, ensuring that the wood chips can be bleached by adding drugs regardless of whether they pass through the bypass screw 108 or the squeeze tearing machine 105.

[0038] See also Figure 4 , Figure 4 It is a flow diagram of another embodiment of the processing system of wood chips for papermaking of the present application, and the processing system comprises: a wood chip storage bin 101, a wood chip washing machine 102, a dehydrator 103, a conveying screw 104, a prepreg feeding screw 111, an extrusion tearing machine 105, a prepreg device 106 and a reaction bin 107 which are arranged in series in sequence; wherein, the processing system further comprises a bypass screw 108 and a dosing device 109. The two ends of the bypass screw 108 are respectively connected to the conveying screw 104 and the reaction bin 107. Under certain working conditions, the wood chips do not pass through the extrusion tearing machine 105 and the (vertical) prepreg device 106, but the bypass screw 108 can directly transfer the wood chips from the conveying screw 104 to the reaction bin 107. The dosing device 109 is connected to the conveying screw 104 and dosing is performed at the position of the conveying screw 104. Optionally, a control valve 110 is provided between the dosing device 109 and the conveying screw 104, and the control valve 110 can be a manual valve. By changing the dosing position, the bleaching efficiency can be improved to ensure that the wood chips passing through the bypass screw 108 or the pre-impregnation feeding screw 111 can be bleached by dosing.

[0039] See also Figure 5 , Figure 5It is a flow diagram of another embodiment of the processing system of wood chips for papermaking of the present application, and the processing system comprises: a wood chip storage bin 101, a wood chip washing machine 102, a dehydrator 103, a conveying screw 104, a prepreg feeding screw 111, an extrusion tearing machine 105, a prepreg device 106, a reaction bin 107, a discharge screw group 112 and a rear section 113 arranged in series in sequence; wherein, the processing system also comprises a bypass screw 108 and a dosing device 109. The two ends of the bypass screw 108 are respectively connected to the conveying screw 104 and the reaction bin 107. Under certain working conditions, the wood chips do not pass through the extrusion tearing machine 105 and the (vertical) prepreg device 106, but the bypass screw 108 can directly transfer the wood chips from the conveying screw 104 to the reaction bin 107. The dosing device 109 is connected to the conveying screw 104 and dosing to the position of the conveying screw 104. Optionally, a control valve 110 is provided between the dosing device 109 and the conveying screw 104. The control valve 110 may be a manual valve. By changing the dosing position, the bleaching efficiency can be improved, ensuring that both the wood chips passing through the bypass screw 108 and the pre-preg feeding screw 111 can be bleached by dosing.

[0040] The unloading screw group 112 is used to unload the wood chips after the reaction in the reaction bin, wherein the unloading screw group 112 may specifically include a reaction bin unloading screw and a plurality of horizontal transmission screws connected in series (described in detail in the subsequent embodiments). The rear section 113 may specifically include high-concentration grinding and other process steps.

[0041] Among them, the conveying screw 104 in this embodiment can be controlled in linkage with the unloading screw group 112 to eliminate the hidden danger of material blocking. In addition, the unloading screw group 112 can participate in the dosing control, and the dosing amount is dynamically adjusted according to the operating conditions.

[0042] By setting a bypass screw, it is possible to switch between two process flows, and to complete the replacement of the wood chip extrusion and tearing machine screw, the reducer, and the screen frame without shutting down the entire line; reduce unplanned shutdowns to ensure smooth production; when copying low-whiteness pulp, bypass is performed to reduce power consumption, reduce operating costs, and extend the life of the gearbox, screw, and screen frame; reduce overtime, reduce emergency repairs, reduce labor intensity, and reduce maintenance costs.

[0043] See also Figure 6 , Figure 6It is a flow chart of another embodiment of the processing system of wood chips for papermaking of the present application, and the processing system includes: a wood chip storage bin 201 (for storing wood chips) arranged in series - a wood chip metering screw 202 (for metering the flow of wood chips) - a 1# wood chip washer 203 - a wood chip pump 204 - a 2# wood chip washer 205 - a 3# wood chip washer 206 - a dewatering screw 207 - a 1# conveying screw 208 - a 2# conveying screw 209 - a prepreg feeding screw 211 - an extrusion tearing machine 212 - a prepreg device 213 - a reaction bin conveying screw 214 - a reaction bin 215 - a reaction bin unloading screw 216 - a 1# horizontal screw 217 - a 2# horizontal screw 219 - a 3# horizontal screw 220 - a double screw 221 - a forced feeding screw 222 - a high concentration grinder 223 - a rear section 224.

[0044] The processing system further includes a bypass screw 210 and a dosing device 218. The two ends of the bypass screw 210 are respectively connected to the 2# conveying screw 209 and the reaction chamber 215. Under certain working conditions, the wood chips do not pass through the prepreg feeding screw 211, the extrusion tearing machine 212, the prepreg device 213 and the reaction chamber conveying screw 214, but the bypass screw 210 can directly transfer the wood chips from the 2# conveying screw 209 to the reaction chamber 215. The dosing device 218 is connected to the 2# conveying screw 209 and dosing at the position of the 2# conveying screw 209. By changing the dosing position, the bleaching efficiency can be improved to ensure that the wood chips can be bleached by dosing whether they pass through the bypass screw 210 or the prepreg feeding screw 211.

[0045] The reaction bin unloading screw 216, the 1# horizontal screw 217, the 2# horizontal screw 219, the 3# horizontal screw 220 and the double screw 221 together constitute an unloading screw group, which is used to unload the wood chips after reaction in the reaction bin.

[0046] The control method of the processing system in this embodiment mainly has the following improvements:

[0047] 1. Add bypass spiral selection function (such as setting button);

[0048] 2. Change the bypass screw motor control logic; including: judging whether the load of the bypass screw (and at least one of the 2# conveying screws) is higher than the preset proportion (for example, 70%) of the load of the unloading screw group (the reaction bin unloading screw 216, the 1# horizontal screw 217, the 2# horizontal screw 219, the 3# horizontal screw 220 and the bottleneck equipment in the double screw 221, that is, the reaction bin unloading screw 216, the 1# horizontal screw 217, the 2# horizontal screw 219, the 3# horizontal screw 220 and the double screw 221), if so, close the bypass screw to avoid material blockage. In addition, it can also include judging whether the material level in the reaction bin is higher than the preset material level (for example, 60%), if so, close the bypass screw (when the bypass screw is working) to avoid material accumulation in the reaction bin, so as to ensure the stable operation of the entire production line.

[0049] 3. The amount of chemical added will be controlled according to the output calculated by the metering screw downstream of the wood chip bin storage bin; in addition, it also includes: linkage with the wood chip unloading group during concentrated grinding unloading to prevent material piling; the liquid level of the pre-impregnation section mixing soda tank controls the speed of the pump outlet; the operation of the wood chip unloading group participates in the control of chemical valves, chemical pumps, etc.

[0050] The papermaking wood chip processing system and processing method in the embodiment of the present application realizes switching between two process flows through spiral bypass, and completes the replacement of the spiral, reducer and screen frame of the wood chip extrusion and tearing machine without shutting down the entire line; reduces unplanned shutdowns and ensures smooth production; when copying low-whiteness pulp, bypass is performed to reduce power consumption, reduce operating costs, and extend the life of the gear box, spiral and screen frame; reduces overtime, reduces emergency repairs, reduces labor intensity, and reduces maintenance costs.

[0051] The wood chips are sent directly to the reaction chamber by the bypass screw across the extrusion tearing machine. When copying low-whiteness pulp, the bypass screw is used for production. The prepreg section is not opened, and the wood chips do not pass through the wood chip extrusion tearing machine and the prepreg, but directly enter the reaction chamber; when the prepreg or the wood chip extrusion tearing machine fails, the bypass method can be used for production. Whether copying low-whiteness or high-whiteness pulp, production can be carried out continuously. Although the cost of chemical consumption per ton of pulp will increase when copying high-whiteness pulp, it is more advantageous than shutting down the entire production line. The bypass screw is used as a permanent screw. After the technical transformation is completed, when the prepreg or the wood chip extrusion tearing machine fails, the bypass can be quickly switched to ensure normal production, and the maintenance personnel have sufficient time to carry out maintenance work.

[0052] By setting up the bypass spiral, during the production process, although the amount of white liquor and total alkali consumption increases, the bleaching efficiency does not decrease. It is higher than the bleaching efficiency of conventional technical solutions. In addition, considering the comprehensive shutdown and production stoppage factors, the benefits are improved.

[0053] The above descriptions are only some embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent device or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A system for processing wood chips for papermaking, characterized in that: The processing system includes: a wood chip storage bin, a wood chip washer, a dehydrator, a conveying screw, an extrusion tearing machine, a prepreg device and a reaction bin which are arranged in series in sequence; wherein, the processing system also includes a bypass screw, the two ends of which are respectively connected to the conveying screw and the reaction bin, and under specific working conditions, the bypass screw can directly transfer the wood chips from the conveying screw to the reaction bin.

2. The processing system according to claim 1, characterized in that The processing system further comprises a drug adding device, which is connected to the conveying screw and adds drugs to the conveying screw position.

3. The processing system according to claim 2, characterized in that A control valve is provided between the dosing device and the conveying screw.

4. The processing system according to claim 1, characterized in that The processing system also includes a prepreg feeding screw, which is connected in series between the conveying screw and the extrusion tearing machine.

5. The processing system according to claim 1, characterized in that The processing system further comprises a discharge screw group, which is connected in series to the reaction bin and is used for discharging the reacted wood chips in the reaction bin.

6. The processing system according to claim 5, characterized in that The unloading spiral group includes a reaction bin unloading spiral and a plurality of horizontal transmission spirals which are connected in series.

7. A method for processing wood chips for papermaking, characterized in that: The processing method uses the processing system described in any one of claims 1 to 6 to process wood chips for papermaking.

8. The processing method according to claim 7, characterized in that: include: Determine whether the bypass screw load is higher than the preset ratio of the unloading screw group load, and if so, close the bypass screw.

9. The processing method according to claim 8, characterized in that: The preset ratio is 70%.

10. The processing method according to claim 7, characterized in that: include: Determine whether the material level in the reaction bin is higher than the preset material level. If so, close the bypass screw.

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