Headbox pulp speed control system for sizing in paper pulp papermaking

Abstract

The utility model discloses a headbox pulp speed control system for pulp papermaking sizing, which comprises a headbox, a forming net, a slushing pump and a control unit, paired lip plates are mounted on one side of the headbox, and lip plate pulp spraying pressure transmitters for detecting pulp are arranged in the lip plates; a net part speed detection sensor for detecting the rotating speed of the forming net is mounted on the forming net; the slushing pump is communicated to the headbox; the control unit is electrically connected with the lip plate guniting pressure transmitter, the net part speed detection sensor and the slushing pump; the control unit can compare pulp pressure data with forming net rotating speed data, and when the pulp net speed ratio is deviated from the preset pulp net speed ratio, the control unit can control the operation rotating speed of the slushing pump so as to control the flow and the flow speed of paper pulp, so that the paper pulp is prevented from being damaged. Therefore, the ratio of the slurry pressure data to the forming net rotating speed data reaches the required slurry net speed ratio, the purpose of controlling the slurry speed of the headbox is achieved, and the current production requirement is met.

Description

Technical Field

[0001] This invention relates to the field of headbox sizing technology, and particularly to a headbox sizing speed control system for papermaking. Background Technology

[0002] The headbox is a crucial component of the paper machine, serving as a vital link between the "powder preparation and flow" and "sheet forming" processes. It determines the basis weight distribution across the paper web, influencing the quality of the formed sheet and is often referred to as the "heart" of the paper machine. During the sizing process, the pulp is ejected from the lip plate of the headbox onto the forming wire. The pressure of the pulp within the headbox affects the ejection speed, while the pulp speed on the wire is the same as the wire speed. If the wire speed is faster than the ejection speed, the fibers in the pulp will be drawn along the wire, resulting in most fibers aligning along the wire's direction of travel (longitudinal). If the wire speed is slower than the ejection speed, the fibers will accumulate on the wire, increasing the fiber alignment along the direction perpendicular to the wire's travel (transverse). Proper transverse fiber alignment increases transverse folding endurance. Therefore, a proper match between the pulp ejection speed and the wire speed is essential.

[0003] Current control methods pre-adjust the flow rate of the feed pump and the dilution water, making it impossible to adjust the pulp pressure according to the actual situation during production to achieve the required pulp flow rate and velocity for various types of paper. This leads to difficulties in controlling the pulp speed in the headbox and makes it impossible to meet production needs. Utility Model Content

[0004] The purpose of this invention is to provide a headbox speed control system for pulp paper making, which aims to solve the problems mentioned above.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] This application provides a headbox flow rate control system for pulp and paper making, including:

[0007] The headbox has a pair of lip plates installed on one side, and the lip plates are equipped with lip plate spray pressure transmitters for detecting slurry.

[0008] A forming screen is disposed on one side of the headbox, and a screen speed detection sensor for detecting the rotational speed of the forming screen is installed on the forming screen;

[0009] The slurry pump has a slurry main pipe at its outlet, and the other end of the slurry main pipe is connected to the slurry box.

[0010] The control unit is electrically connected to the lip plate spraying pressure transmitter, the mesh speed detection sensor, and the grouting pump, and is used to control the rotation speed of the grouting pump in order to control the grout speed.

[0011] In one possible implementation, the control unit includes a proportional-integral-derivative controller, a computing unit, and a main operating computer;

[0012] The main operating computer is electrically connected to the proportional-integral-derivative controller and the calculation unit; the calculation unit is electrically connected to the proportional-integral-derivative controller.

[0013] In one possible implementation, the proportional-integral-derivative controller is electrically connected to the lip plate spray pressure transmitter.

[0014] In one possible implementation, a first analog signal conversion module is provided between the proportional-integral-derivative controller and the lip plate spraying pressure transmitter.

[0015] In one possible implementation, the network speed detection sensor is electrically connected to the computing unit.

[0016] In one possible implementation, a second analog signal conversion module is provided between the network speed detection sensor and the computing unit.

[0017] In one possible implementation, the proportional-integral-derivative controller is electrically connected to the slurry pump.

[0018] In one possible implementation, the proportional-integral-derivative controller is electrically connected in sequence to the grouting pump via a frequency converter and a grouting pump motor.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0020] In this invention, the control unit can compare the pulp pressure data and the forming wire rotation speed data. The control unit can set the pulp-wire speed ratio. When there is a deviation between the pulp-wire speed ratio and the preset pulp-wire speed ratio, the control unit can control the operating speed of the pulp pump to control the pulp flow rate and velocity, so that the ratio of the pulp pressure data and the forming wire rotation speed data reaches the required pulp-wire speed ratio. This achieves the purpose of controlling the pulp speed of the headbox and meets the current production needs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the principle structure of this utility model.

[0022] The diagram shows: 1. Headbox; 101. Lip plate spray pressure transmitter; 2. Forming mesh; 201. Mesh speed sensor; 3. Slurry pump; 4. Main slurry pipe; 5. Proportional-integral-derivative controller; 6. Calculation unit; 7. Main operating computer; 8. First analog signal conversion module; 9. Second analog signal conversion module; 10. Frequency converter; 11. Slurry pump motor. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0024] First, use Figure 1 The overall structure of the headbox speed control system for pulp and paper making is described. Figure 1 This is a schematic diagram of the principle structure of this utility model.

[0025] This pulp and paper making headbox speed control system includes a headbox 1, a forming wire 2, a slurry pump 3, and a control unit, wherein:

[0026] A pair of lip plates are installed on one side of the headbox 1, with a nozzle between the two lip plates for ejecting pulp. A lip plate ejection pressure transmitter 101 for detecting the pulp pressure is installed inside the lip plate, and the lip plate ejection pressure transmitter 101 is electrically connected to the control unit. The pulp pressure data detected by the lip plate ejection pressure transmitter 101 can be output to the control unit.

[0027] The forming net 2 is located on one side of the headbox 1. During the sizing process, sizing is ejected from the lip plate of the headbox 1 onto the forming net 2. A net speed detection sensor 201 is installed on the forming net 2 to detect its rotational speed. The net speed detection sensor 201 is electrically connected to the control unit. The net speed detection sensor 201 can detect the rotational speed data of the forming net 2, and the detected rotational speed data can be output to the control unit.

[0028] The grout outlet of the grout pump 3 is equipped with a grout supply main pipe 4, and the other end of the grout supply main pipe 4 is connected to the headbox 1. The grout pump 3 can transport grout to the headbox 1 through the grout supply main pipe 4, and the grout can be sprayed out along the middle of the lip plate of the headbox 1.

[0029] The control unit is electrically connected to the lip plate spraying pressure transmitter 101, the mesh speed detection sensor 201, and the grout pump 3 to control the rotation speed of the grout pump 3 in order to control the grout speed.

[0030] In this embodiment, the lip plate spray pressure transmitter 101 can output the slurry pressure data detected at the lip plate to the control unit, and the wire speed detection sensor 201 can detect the rotational speed data of the forming wire 2, and the rotational speed data detected by the wire speed detection sensor 201 can also be output to the control unit. The control unit can compare the slurry pressure data and the rotational speed data of the forming wire 2. The control unit can set the slurry-wire speed ratio (slurry-wire speed ratio setpoint). When there is a deviation between the slurry-wire speed ratio and the preset slurry-wire speed ratio, the control unit can control the operating speed of the slurry pump 3 to control the pulp flow rate and velocity, so that the ratio of the slurry pressure data and the rotational speed data of the forming wire 2 reaches the required slurry-wire speed ratio, thus achieving the purpose of controlling the slurry speed of the headbox 1 and meeting the current production needs.

[0031] In some embodiments, such as Figure 1 As shown. The specific structure and working principle of the control unit are as follows: The control unit includes a proportional-integral-derivative controller 5, a calculation unit 6, and a main operating computer 7.

[0032] The main operating computer 7 is electrically connected to the proportional-integral-differential controller 5 and the calculation unit 6; the calculation unit 6 is electrically connected to the proportional-integral-differential controller 5.

[0033] The proportional-integral-derivative (PID) controller 5 is electrically connected to the lip plate shotcrete pressure transmitter 101, and a first analog signal conversion module 8 is provided between the PID controller 5 and the lip plate shotcrete pressure transmitter 101. After the lip plate shotcrete pressure transmitter 101 detects the pressure of the slurry at the lip plate, the pressure signal detected by the lip plate shotcrete pressure transmitter 101 is an analog signal. The first analog signal conversion module 8 can convert the analog signal into a digital signal, and the digital signal can be output to the PID controller 5. After that, the digital signal of the shotcrete pressure value detected by the lip plate shotcrete pressure transmitter 101 is divided into two paths for transmission: one path is transmitted to the PID controller 5, and the other path is transmitted to the calculation unit 6.

[0034] The mesh velocity detection sensor 201 is electrically connected to the computing unit 6, and a second analog signal conversion module 9 is provided between the mesh velocity detection sensor 201 and the computing unit 6. When the lip plate shotcrete pressure transmitter 101 detects the shotcrete pressure, the mesh velocity detection sensor 201 simultaneously detects the mesh velocity. The detected mesh velocity is converted into a shotcrete speed digital signal by the second analog signal conversion module 9, and the shotcrete speed digital signal is also transmitted to the computing unit 6.

[0035] The proportional-integral-derivative (PID) controller 5 is electrically connected to the grout pump 3. The PID controller 5 and the grout pump 3 are connected in sequence by a frequency converter 10 and a grout pump motor 11. The PID controller 5 can control the frequency converter 10 and the grout pump motor 11, thereby achieving the purpose of controlling the grouting speed of the grout pump 3.

[0036] In this implementation scheme, during the sizing process, the operator inputs the required pulp-to-wire speed ratio (pulp-to-wire speed ratio setting value) on the main operating computer 7, and this number will be displayed on the main operating computer 7.

[0037] The following calculations are performed in calculation unit 6:

[0038] 1. Convert the grouting pressure inside the lip plate into grouting velocity; this grouting velocity is the actual grouting velocity.

[0039] 2. Calculate the ratio of pulp speed to screen speed (pulp-screen speed ratio to actual value) based on the actual pulp speed and the screen speed of forming screen 2. This number will be transmitted to the main operating computer 7 and displayed on the main operating computer 7.

[0040] 3. Calculate the set value of the pulp speed based on the ratio of the pulp speed to the forming screen 2.

[0041] 4. Calculate the set value of grout pressure based on the set value of grouting rate;

[0042] 5. Then the set value of the grout pressure is transmitted from the calculation unit 6 to the proportional-integral-derivative controller 5;

[0043] 6. In the proportional-integral-derivative controller 5, the set value of the grout pressure is converted into the set value of the speed of the grout pump motor 11.

[0044] Following the steps above, you can then select "Automatic" or "Manual" mode via the main operating computer 7.

[0045] In "automatic" mode, the proportional-integral-derivative controller 5 transmits the set value of the speed of the grout pump motor 11 to the frequency converter 10. The frequency converter 10 controls the grout pump motor 11 to gradually reach the set value speed, thereby changing the actual grout pressure ejected from the lip plate.

[0046] As before, the actual grout pressure signal detected by the lip plate grouting pressure transmitter 101 is transmitted in two ways. One way is transmitted to the proportional-integral-derivative controller 5. The proportional-integral-derivative controller 5 compares the set value of the grout pressure transmitted from the calculation unit 6 with the actual grout pressure. If there is a deviation, it issues a command to control the frequency converter 10, the grout pump motor 11 and the grout pump 3 to continue adjusting. If the deviation is 0, it issues a command to terminate the adjustment.

[0047] The actual grout pressure signal detected by the lip plate shotcrete pressure transmitter 101 is transmitted to the calculation unit 6 to calculate the actual grout mesh speed ratio. When the deviation between the set value of the grout pressure and the actual grout pressure is 0, the actual grout mesh speed ratio will be equal to the required grout mesh speed ratio.

[0048] In "manual" mode, the proportional-integral-derivative controller 5 no longer converts the set value of the slurry pressure transmitted from the calculation unit 6 into the set value of the speed of the slurry pump motor 11. Instead, the operator compares the actual slurry-mesh speed ratio displayed on the main operating computer 7 with the required slurry-mesh speed ratio and manually inputs the set value of the speed of the slurry pump 3 into the main operating computer 7. The proportional-integral-derivative controller 5 transmits this speed set value to the frequency converter 10, and then the frequency converter 10 controls the speed of the slurry pump motor 11 to change the slurry speed until the required slurry-mesh speed ratio is reached.

[0049] This invention detects and calculates the pulp pressure at the lip plate and the wire speed of the forming wire 2, and uses a main operating computer 7, a proportional-integral-derivative controller 5, and a frequency converter 10 for control. This ensures that the pulp-wire speed ratio meets the requirements during process adjustment, achieving the required pulp flow rate and velocity for various types of paper. The pulp speed control of the headbox 1 is convenient, ensuring that the fibers always maintain a suitable transverse alignment, thereby improving the folding endurance of the finished paper and meeting production needs.

[0050] In the description of this utility model, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0051] Furthermore, in the description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0052] On the other hand, it should be noted that, unless otherwise explicitly specified and limited, the terms "located at," "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

Claims

1. A headbox speed control system for pulp and paper making, characterized in that, include: The headbox (1) has a pair of lip plates installed on one side, and the lip plates are equipped with a lip plate spray pressure transmitter (101) for detecting the slurry. A forming mesh (2) is provided on one side of the headbox (1), and a mesh speed detection sensor (201) for detecting the rotational speed of the forming mesh (2) is installed on the forming mesh (2); The slurry pump (3) has a slurry outlet equipped with a slurry main pipe (4), and the other end of the slurry main pipe (4) is connected to the headbox (1); The control unit is electrically connected to the lip plate spraying pressure transmitter (101), the mesh speed detection sensor (201), and the grout pump (3) to control the rotation speed of the grout pump (3) in order to control the grout speed.

2. The headbox speed control system for pulp and paper making according to claim 1, characterized in that, The control unit includes a proportional-integral-derivative controller (5), a computing unit (6), and a main operating computer (7); The main operating computer (7) is electrically connected to the proportional-integral-derivative controller (5) and the calculation unit (6); the calculation unit (6) is electrically connected to the proportional-integral-derivative controller (5).

3. The headbox speed control system for pulp and paper making according to claim 2, characterized in that, The proportional-integral-derivative controller (5) is electrically connected to the lip plate spraying pressure transmitter (101).

4. The headbox speed control system for pulp and paper making according to claim 3, characterized in that, A first analog signal conversion module (8) is provided between the proportional-integral-derivative controller (5) and the lip plate spraying pressure transmitter (101).

5. The headbox speed control system for pulp and paper making according to claim 2, characterized in that, The mesh speed detection sensor (201) is electrically connected to the computing unit (6).

6. The headbox speed control system for pulp and paper making according to claim 5, characterized in that, A second analog signal conversion module (9) is provided between the network speed detection sensor (201) and the computing unit (6).

7. The headbox speed control system for pulp and paper making according to claim 2, characterized in that, The proportional-integral-derivative controller (5) is electrically connected to the slurry pump (3).

8. The headbox speed control system for pulp and paper making according to claim 7, characterized in that, The proportional-integral-derivative controller (5) is electrically connected to the grouting pump (3) via a frequency converter (10) and a grouting pump motor (11).

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