A medium concentration automatic slurry preparation flow concentration control device

Abstract

The application discloses a medium-concentration automatic pulp preparation flow concentration control device, which comprises a broke tower system, a long fiber post-beating tower system, a first short fiber post-beating tower system, a second short fiber post-beating tower system and a mixed pulp pool; the pulp from the above four systems is injected into the mixed pulp pool, and the mixed pulp pool is kept at a constant liquid level. The method comprises the following steps: the broke tower system receives broke from a broke recycling system, the long fiber post-beating tower system, the first short fiber post-beating tower system and the second short fiber post-beating tower system respectively receive post-beating pulp from different fiber raw materials; four flow control units adjust flow through four flow control valves, and four concentration control units adjust concentration through four concentration control valves; the pulp from the four systems is injected into the mixed pulp pool, and the mixed pulp pool is kept at a constant liquid level. In the design of the application, a medium-concentration pulp system is designed, the short fiber is changed into medium-concentration pulp after medium-concentration beating, and the medium-concentration pulp is used more to reduce production cost under the premise of ensuring paper quality.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, and in particular to an automatic medium-consistency pulp mixing flow rate and concentration control device. Background Technology

[0002] The manufacturing process of toilet paper involves the use of long-fiber pulp and short-fiber pulp in a specific ratio. Long-fiber pulp is more expensive than short-fiber pulp. Therefore, in the actual production process, long-fiber pulp should be used as little as possible while ensuring physical properties such as tensile strength, in order to reduce production costs. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a medium-consistency automatic pulping flow and concentration control device, and to design a medium-consistency pulping system in which short fibers are turned into medium-consistency pulp after passing through the medium-consistency mill. Under the premise of ensuring paper quality, more medium-consistency pulp is used, thereby reducing production costs.

[0004] To solve the above-mentioned technical problems, the present invention provides a medium-consistency automatic pulping flow rate and concentration control device, comprising: a paper-breaking tower system, a long fiber knockdown tower system, a first short fiber knockdown tower system, a second short fiber knockdown tower system, and a mixing pulp tank; the pulp is injected into the mixing pulp tank after being refined through the above four systems, and the mixing pulp tank is kept at a constant liquid level.

[0005] Preferably, the paper loss tower system includes a paper loss tower, a first switching valve, a first concentration control valve, a first concentration control unit, a first slurry pump, a first flow control unit, and a first flow control valve; the paper loss tower, the first switching valve, the first slurry pump, and the first flow control valve are connected in sequence, the first concentration control unit is connected to the first slurry pump through the first concentration control valve, and the first flow control unit is connected to the first flow control valve.

[0006] Preferably, the long fiber post-press tower system includes a long fiber post-press tower, a second switching valve, a second concentration control valve, a second concentration control unit, a second slurry pump, a second flow control unit, a second flow control valve, and a first concentration rotary motor; the long fiber post-press tower, the second switching valve, the second slurry pump, the first concentration rotary motor, and the second flow control valve are connected in sequence, the second concentration control unit is connected to the second slurry pump through the second concentration control valve, and the second flow control unit is connected to the second flow control valve.

[0007] Preferably, the first short fiber tapping tower system includes a short fiber tapping tower, a third switching valve, a third concentration control valve, a third concentration control unit, a third slurry pump, a third flow control unit, a third flow control valve, and a second concentration rotary motor; the short fiber tapping tower, the third switching valve, the third slurry pump, the second concentration rotary motor, and the third flow control valve are connected in sequence, the third concentration control unit is connected to the third slurry pump through the third concentration control valve, and the third flow control unit is connected to the third flow control valve.

[0008] Preferably, the second short fiber knockdown tower system has the same structure as the first short fiber knockdown tower system.

[0009] Accordingly, a method for controlling the flow rate and concentration of medium-consistency automatic pulp mixing includes the following steps:

[0010] Step 1: The waste paper tower system receives waste paper from the waste paper recycling system, while the long fiber knockdown tower system, the first short fiber knockdown tower system, and the second short fiber knockdown tower system receive knockdown pulp from different fiber raw materials respectively.

[0011] Step 2: The four flow control units regulate the flow rate through four flow control valves, and the four concentration control units regulate the concentration through four concentration control valves.

[0012] Step 3: Inject the compliant pulp from the four systems into the mixing tank, keeping the mixing tank at a constant liquid level.

[0013] Preferably, the second concentration rotary motor is used to measure the slurry concentration, and the third concentration control valve is used to adjust the dilution water flow rate to control the slurry concentration; in the concentration control unit, The parameters are derived from the 4-20mA output electrical signal of the second concentration rotary motor, where the instrument's concentration unit is set to %, and the range is 2-6. The DCS system receives the corresponding current signal, converts it into the actual measured concentration, and then uses the concentration control PID formula to calculate the valve output value. The DCS system sends a corresponding 4-20mA current signal to the third concentration control valve, which then adjusts the dilution water flow rate; (PID parameters...) and Used to adjust the stability of PID control.

[0014] Preferably, the third flow control unit is used to measure the slurry flow rate, and the third flow control valve is used to adjust the size of the outlet valve, thereby controlling the flow rate; in the flow control unit, The parameters are derived from the 4-20mA output electrical signal of the third flow control unit, where the instrument's set flow unit is l / min and the range is 0-8000. The DCS system receives the corresponding current signal, converts it into the actual measured flow rate, and then uses the flow control PID formula to calculate the valve output value. The DCS system sends a corresponding 4-20mA current signal to the third flow control valve, which then adjusts the flow rate; in the PID parameters... and Used to adjust the stability of PID control.

[0015] Preferably, the concentration control PID and the flow control PID are:

[0016]

[0017] in, For PID output value, For proportional gain, The difference between the set value and the measured value. For the execution interval, For the time of integration, The differential action time, For measured values, For feedforward shunt gain, For feedforward channel input, This is the deviation parameter.

[0018] Preferably, the level transmitter in the mixing tank measures and outputs an electrical signal of 4-20mA to the DCS system, which converts it into the corresponding 0-100% actual flow rate; the level PID loop outputs con*total flow rate 5000 l / min to obtain a calculated flow rate, and the calculated flow rate * the medium-concentration ratio = the medium-concentration set flow rate.

[0019] The beneficial effects of this invention are as follows: This invention designs a medium-consistency pulping system. Short-fiber hardwood pulp is increased from 4% to 20% using a medium-consistency screw press. The pulp fibers are then rubbed by a disc mill to alter the pulp's physical properties. After passing through a post-refinement pulp tank to adjust the pulp concentration to 4%, it flows to the finishing mill to become medium-consistency pulp. This allows for the use of more medium-consistency pulp while ensuring paper quality, thus reducing production costs. Furthermore, by maintaining the ratio of the four pulps, the mixing tank is kept at a constant liquid level, and the inlet pressure of the mixing tank pump is kept stable, which is beneficial for stable pulping power in the subsequent leveling mill, ensuring pulp quality. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the control device structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0022] like Figure 1 As shown, a medium-consistency automatic pulping flow rate and concentration control device includes: a paper-breaking tower system, a long fiber knockdown tower system, a first short fiber knockdown tower system, a second short fiber knockdown tower system, and a mixing pulp tank; the pulp is injected into the mixing pulp tank after being refined through the above four systems, and the mixing pulp tank is kept at a constant liquid level.

[0023] The paper loss tower system includes a paper loss tower 11, a first switching valve 12, a first concentration control valve 13, a first concentration control unit 14, a first slurry pump 15, a first flow control unit 16, and a first flow control valve 17. The paper loss tower 11, the first switching valve 12, the first slurry pump 15, and the first flow control valve 17 are connected in sequence. The first concentration control unit 14 is connected to the first slurry pump 15 through the first concentration control valve 13, and the first flow control unit 16 is connected to the first flow control valve 17.

[0024] The long fiber post-press tower system includes a long fiber post-press tower 21, a second switching valve 22, a second concentration control valve 23, a second concentration control unit 24, a second slurry pump 25, a second flow control unit 26, a second flow control valve 27, and a first concentration rotary motor 28. The long fiber post-press tower 21, the second switching valve 22, the second slurry pump 25, the first concentration rotary motor 28, and the second flow control valve 27 are connected in sequence. The second concentration control unit 24 is connected to the second slurry pump 25 through the second concentration control valve 23, and the second flow control unit 26 is connected to the second flow control valve 27.

[0025] The first short fiber post-press tower system includes a first short fiber post-press tower 31, a third switching valve 32, a third concentration control valve 33, a third concentration control unit 34, a third slurry pump 35, a third flow control unit 36, a third flow control valve 37, and a second concentration rotary motor 38. The short fiber post-press tower 31, the third switching valve 32, the third slurry pump 35, the second concentration rotary motor 38, and the third flow control valve 37 are connected in sequence. The third concentration control unit 34 is connected to the third slurry pump 35 through the third concentration control valve 33, and the third flow control unit 36 ​​is connected to the third flow control valve 37.

[0026] The second short fiber post-press tower system includes a second short fiber post-press tower 41, a fourth switching valve 42, a fourth concentration control valve 43, a fourth concentration control unit 44, a fourth slurry pump 45, a fourth flow control unit 46, a fourth flow control valve 47, and a third concentration rotary motor 48. The second short fiber post-press tower 41, the fourth switching valve 42, the fourth slurry pump 45, the third concentration rotary motor 48, and the fourth flow control valve 47 are connected in sequence. The fourth concentration control unit 44 is connected to the fourth slurry pump 45 through the fourth concentration control valve 43, and the fourth flow control unit 46 is connected to the fourth flow control valve 47.

[0027] like Figure 2 As shown, a method for controlling the flow rate and concentration of medium-consistency automatic pulp mixing includes the following steps:

[0028] Step 1: The waste paper tower system receives waste paper from the waste paper recycling system, and the long fiber knocking tower system 21, the first short fiber knocking tower system 31, and the second short fiber knocking tower system 41 respectively receive knocking pulp from different fiber raw materials.

[0029] Step 2: The four flow control units regulate the flow rate through four flow control valves, and the four concentration control units regulate the concentration through four concentration control valves.

[0030] Step 3: Inject the compliant grinding pulp from the four systems into the mixing tank 5, and keep the mixing tank at a constant liquid level.

[0031] The second concentration rotary motor 38 is used to measure the pulp concentration, and the third concentration control valve 33 is used to adjust the dilution water flow rate to control the pulp concentration; in the concentration control unit... The parameters are derived from the 4-20mA output electrical signal of the second concentration rotary motor 38, where the instrument's concentration unit is set to %, and the range is 2-6. The DCS system receives the corresponding current signal, converts it into the actual measured concentration, and then uses the concentration control PID formula to calculate the valve output value. The DCS system sends a corresponding 4-20mA current signal to the third concentration control valve 33, which adjusts the dilution water flow rate; in the PID parameters... and Used to adjust the stability of PID control.

[0032] The third flow control unit 36 ​​is used to measure the slurry flow rate, and the third flow control valve 37 is used to adjust the size of the outlet valve, thereby controlling the flow rate; in the flow control unit, The parameters are derived from the 4-20mA output electrical signal of the third flow control unit 36, where the instrument's set flow unit is l / min and the range is 0-8000. The DCS system receives the corresponding current signal, converts it into the actual measured flow rate, and then uses the flow control PID formula to calculate the valve output value. The DCS system sends a corresponding 4-20mA current signal to the third flow control valve 37, which adjusts the flow rate; in the PID parameters... and Used to adjust the stability of PID control.

[0033] The concentration control PID and flow control PID are:

[0034]

[0035] in, For PID output value, For proportional gain, The difference between the set value and the measured value. For the execution interval, For the time of integration, The differential action time, For measured values, For feedforward shunt gain, For feedforward channel input, This is the deviation parameter.

[0036] The mixing tank 5 is equipped with a liquid level transmitter that measures and outputs an electrical signal of 4-20mA to the DCS system. The DCS system converts this signal into the corresponding 0-100% actual flow rate. The liquid level PID loop outputs con*total flow rate 5000 l / min to obtain a calculated flow rate. The calculated flow rate * the medium-concentration ratio = the medium-concentration set flow rate.

[0037] After the medium-consistency pulp system was put into operation in March 2023, the price of long fiber was approximately 5,646 yuan per ton and that of short fiber was 4,020 yuan per ton in May 2023. Short fiber is converted into medium-consistency pulp after passing through the medium-consistency mill. Under the premise of ensuring paper quality, using more medium-consistency pulp and less long fiber can reduce long fiber consumption by 6%. After deducting electricity consumption, the annualized benefit of long fiber reduction per paper machine = 78 yuan / ton * 3,800 tons * 12 months = 3,556,800 yuan.

Claims

1. A medium-consistency automatic pulp mixing flow rate and concentration control device, characterized in that, include: The pulp consists of a pulping tower system, a long fiber knockdown tower system, a first short fiber knockdown tower system, a second short fiber knockdown tower system, and a mixing tank. The pulp is then injected into the mixing tank after passing through these four systems, maintaining a constant liquid level in the mixing tank. The process includes the following steps: Step 1: The waste paper tower system receives waste paper from the waste paper recycling system, while the long fiber knockdown tower system, the first short fiber knockdown tower system, and the second short fiber knockdown tower system receive knockdown pulp from different fiber raw materials respectively. Step 2: The four flow control units regulate the flow rate through four flow control valves. The third flow control unit measures the slurry flow rate, and the third flow control valve adjusts the outlet valve size, thereby controlling the flow rate. Within the flow control units... The parameters are derived from the 4-20mA output electrical signal of the third flow control unit, where the instrument's set flow unit is l / min and the range is 0-8000. The DCS system receives the corresponding current signal, converts it into the actual measured flow rate, and then uses the flow control PID formula to calculate the valve output value. The DCS system sends a corresponding 4-20mA current signal to the third flow control valve, which then adjusts the flow rate; in the PID parameters... and Used to adjust the stability of PID control; Four concentration control units regulate the concentration via four concentration control valves; a second concentration rotary motor measures the slurry concentration, and a third concentration control valve adjusts the dilution water flow rate to control the slurry concentration; within the concentration control units... The parameters are derived from the 4-20mA output electrical signal of the second concentration rotary motor, where the instrument's concentration unit is set to %, and the range is 2-6. The DCS system receives the corresponding current signal, converts it into the actual measured concentration, and then uses the concentration control PID formula to calculate the valve output value. The DCS system sends a corresponding 4-20mA current signal to the third concentration control valve, which then adjusts the dilution water flow rate; (PID parameters...) and Used to adjust the stability of PID control; Step 3: Inject the compliant pulp from the four systems into the mixing tank, keeping the mixing tank at a constant level. The mixing tank is measured by a level transmitter, which outputs a 4-20mA electrical signal to the DCS system. The DCS converts this signal into the corresponding 0-100% actual flow rate. The level PID loop outputs con * total flow rate 5000 l / min to obtain a calculated flow rate. Calculated flow rate * medium-concentration ratio = medium-concentration set flow rate.

2. The medium-consistency automatic pulp mixing flow rate and concentration control device as described in claim 1, characterized in that, The paper loss tower system includes a paper loss tower, a first switching valve, a first concentration control valve, a first concentration control unit, a first slurry pump, a first flow control unit, and a first flow control valve. The paper loss tower, the first switching valve, the first slurry pump, and the first flow control valve are connected in sequence. The first concentration control unit is connected to the first slurry pump through the first concentration control valve, and the first flow control unit is connected to the first flow control valve.

3. The medium-consistency automatic pulp mixing flow rate and concentration control device as described in claim 1, characterized in that, The long fiber post-press tower system includes a long fiber post-press tower, a second switching valve, a second concentration control valve, a second concentration control unit, a second slurry pump, a second flow control unit, a second flow control valve, and a first concentration rotary motor. The long fiber post-press tower, the second switching valve, the second slurry pump, the first concentration rotary motor, and the second flow control valve are connected in sequence. The second concentration control unit is connected to the second slurry pump through the second concentration control valve, and the second flow control unit is connected to the second flow control valve.

4. The medium-consistency automatic pulp mixing flow rate and concentration control device as described in claim 1, characterized in that, The first short fiber tapping tower system includes a short fiber tapping tower, a third switching valve, a third concentration control valve, a third concentration control unit, a third slurry pump, a third flow control unit, a third flow control valve, and a second concentration rotary motor. The short fiber tapping tower, the third switching valve, the third slurry pump, the second concentration rotary motor, and the third flow control valve are connected in sequence. The third concentration control unit is connected to the third slurry pump through the third concentration control valve, and the third flow control unit is connected to the third flow control valve.

5. The medium-consistency automatic pulp mixing flow rate and concentration control device as described in claim 1, characterized in that, The second short fiber knockdown tower system has the same structure as the first short fiber knockdown tower system.

6. The medium-consistency automatic pulp mixing flow rate and concentration control device as described in claim 1, characterized in that, The concentration control PID and flow control PID are: in, For PID output value, For proportional gain, The difference between the set value and the measured value. For the execution interval, For the time of integration, The differential action time, For measured values, For feedforward shunt gain, For feedforward channel input, This is the deviation parameter.

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