CN107938414B

CN107938414B - Liquid discharge control method of pulp bleaching system

Info

Publication number: CN107938414B
Application number: CN201710977065.5A
Authority: CN
Inventors: 罗鸣; 汪水财; 叶明扬; 朱芳林; 张九玲; 戴光明
Original assignee: China Xuan Paper Co ltd
Current assignee: China Xuan Paper Co ltd
Priority date: 2017-10-19
Filing date: 2017-10-19
Publication date: 2020-07-14
Anticipated expiration: 2037-10-19
Also published as: CN107938414A

Abstract

The invention belongs to the technical field of papermaking equipment, and particularly relates to a liquid discharge control method of a pulp bleaching system, which comprises the following steps: A. a liquid level sensor is arranged on the tank wall of a slurry tank in the slurry floating system, the liquid level sensor is arranged at a water level height warning value K1, and K1 is close to the notch of the slurry tank; B. a liquid pumping device is arranged on a liquid discharge pipeline for discharging filtrate in the slurry tank, and a liquid level sensor acquires water level height information in the slurry tank so as to monitor the water level height in the slurry tank; when the height of the water level in the slurry tank is greater than K1, the liquid pumping device is started and discharges liquid outwards from the slurry tank, and when the height of the water level in the slurry tank is less than or equal to K1, the liquid pumping device is in a standby state. The invention can build the siphon drainage in time when the water level in the slurry tank is proper, and can start the liquid pumping device to assist drainage in time when the slurry flow is overlarge, thereby avoiding the raw material waste and production interruption caused by the overflow of the slurry out of the slurry tank, effectively ensuring the washing and concentrating effects of the slurry and ensuring the operation quality of the slurry bleaching.

Description

Liquid discharge control method of pulp bleaching system

Technical Field

The invention belongs to the technical field of papermaking equipment, and particularly relates to a liquid discharge control method of a pulp bleaching system.

Background

The bleaching pulp is an important process in the production of papermaking and pulp pulping and is used for realizing the bleaching and washing of pulp. Generally, a bleaching agent is added into the pulp, after the pulp is bleached to meet the process requirements, washing water is added and the pulp is fully washed, then the mixed pulp is driven to flow through a flat-plate-shaped filter screen which is fully covered with a flow passage of the pulp, papermaking fibers can still remain in the pulp after being intercepted by the filter screen, and filtrate containing residual bleaching agent passes through the filter screen and is discharged, so that the washing and the concentration of the pulp are realized.

The filtrate can be discharged by utilizing the siphon principle, but the water level in the pulp tank is influenced by the mixing operation progress of the paper pulp and the bleaching solution, the pulp flow is unstable, the siphon liquid drainage is not timely due to the overhigh water level in the pulp tank, and the pulp overflows out of the pulp tank to waste a large amount of raw materials and even cause production interruption; the water level in the dressing trough drops to siphon pipeline water inlet below, then the siphon flowing back will be interrupted, even the water level in the dressing trough resumes to the working water level, because the unable automatic establishment of siphon flowing back, the system of floating the thick liquid also can't continue the operation for the thick liquid quality can not satisfy the production demand.

Disclosure of Invention

The invention aims to provide a liquid discharge control method of a bleaching system, which can effectively ensure the bleaching quality.

In order to realize the purpose, the invention adopts the technical scheme that: a liquid discharge control method of a bleaching system comprises the following steps: A. a liquid level sensor is arranged on the tank wall of a slurry tank in the slurry floating system, the liquid level sensor is arranged at a water level height warning value K1, and K1 is close to the notch of the slurry tank; B. a liquid pumping device is arranged on a liquid discharge pipeline for discharging filtrate in the slurry tank, and a liquid level sensor acquires water level height information in the slurry tank so as to monitor the water level height in the slurry tank; when the height of the water level in the slurry tank is greater than K1, the liquid pumping device is started and discharges liquid outwards from the slurry tank, and when the height of the water level in the slurry tank is less than or equal to K1, the liquid pumping device is in a standby state.

Compared with the prior art, the invention has the following technical effects: the siphon liquid drainage can be timely established when the water level in the slurry tank is appropriate, the pump liquid device can be timely started to assist liquid drainage when the flow of the slurry is too large, raw material waste and production interruption caused by the slurry overflowing the slurry tank are avoided, and therefore washing and concentration effects of the slurry are effectively guaranteed, and the operation quality of the slurry bleaching is guaranteed.

Drawings

The contents of the description and the references in the drawings are briefly described as follows:

FIG. 1 is a schematic view of the present invention;

fig. 2 is a schematic diagram of another embodiment of the present invention.

In the figure: 1. the device comprises a slurry tank, 11 liquid level sensors, 2 liquid discharge pipelines, 21 hollow pipes, 22 liquid inlet pipes, 23 liquid outlet pipes, 24 liquid pumping pipes, 25 gas guide pipes, 3 liquid pumping devices, 4 filtering units, 5 liquid discharge tanks and 6 gas guide valves.

Detailed Description

The following description of the embodiments of the present invention will be made in detail with reference to the accompanying drawings.

A liquid discharge control method of a bleaching system comprises the following steps:

A. a liquid level sensor 11 is arranged on the tank wall of a slurry tank 1 in a slurry floating system, the liquid level sensor 11 is arranged at a water level height warning value K1, and K1 is close to the notch of the slurry tank 1;

B. a liquid pumping device 3 is arranged on a liquid discharge pipeline 2 for discharging filtrate in the slurry tank 1, and a liquid level sensor 11 collects water level height information in the slurry tank 1 to monitor the water level height in the slurry tank 1; when the water level height in the size tank 1 is greater than K1, the liquid pumping device 3 is started and discharges liquid from the size tank 1, and when the water level height in the size tank 1 is less than or equal to K1, the liquid pumping device 3 is in a standby state.

Therefore, when the floating slurry system works for the first time, after the water level in the slurry tank 1 rises to the position of the liquid level sensor 11, the pump liquid device 3 is started to enable filtrate in the slurry tank 1 to be rapidly discharged through the liquid discharge pipeline 2, the water level in the slurry tank 1 gradually drops along with the discharge of the filtrate, after the water level in the slurry tank 1 drops to the position below the liquid level sensor 11, the pump liquid device 3 stops working, siphon liquid flow is built in the liquid discharge pipeline 2, the filtrate is continuously discharged under the condition of no external force driving, and the liquid discharge cost is effectively saved. When the siphon flowing back of flowing back pipeline 2 was maintained, if the water level in stock chest 1 rose to level sensor 11 department once more, pump liquid device 3 starts and discharges the liquid and can avoid the stock chest 1 in the stock chest to overflow outside the groove and cause the thick liquid extravagant, avoid the emergence of production accident. If the water level in the stock chest 1 drops to the position below the water inlet end of the liquid discharge pipeline 2, so that siphoning is stopped, filtrate cannot be discharged continuously, the water level in the stock chest 1 gradually rises, and after the water level rises to the position of the liquid level sensor 11 again, the liquid pumping device 3 starts the establishment of auxiliary siphoning liquid flow again. The operation is circulated, so that the working stability and reliability of the slurry floating system can be effectively ensured, and the slurry floating quality is ensured.

That is to say, the liquid pumping device 3 and the liquid level sensor 11 work cooperatively, which can help the liquid discharge pipeline 2 to establish siphon liquid flow, so that the liquid discharge pipeline 2 can stably discharge filtrate without external force driving, and the production cost is effectively reduced; also can start when the thick liquid flow is too big, the siphon flowing back can not satisfy the flowing back demand to accelerate flowing back efficiency, guarantee the drift quality.

Preferably, the depth of the K1 is more than or equal to that of the slurry tank 1

The water level altitude warning value K1 may be the depth of the groove

Or other value, but K1 should be greater than the depth of the vat 1

Make level sensor 11 locate in stock chest 1 on being close to the cell wall of notch department, level sensor 11 and pump liquid device 3 combined action like this can guarantee the establishment of siphon liquid flow in drain pipe 2, guarantee the stability and the reliability of siphon flowing back, can also avoid stock chest 1 in the overflow that the water level rises and leads to at the excessive speed.

Specifically, the notch department of dressing trough 1 is equipped with filter unit 4, and the inlet of drain line 2 is located filter unit 4's filter screen and encloses in the closed region, outside the liquid outlet extends to dressing trough 1, and the inlet of drain line 2 is higher than the liquid outlet. As shown in figure 1, when the filter unit 4 is used, part of the column body of the filter unit 4 is immersed in slurry, after the slurry flows through the filter unit 4, filtrate in the area enclosed by the filter screen of the filter unit 4 can be discharged through the liquid discharge pipeline 2 by utilizing the siphon principle under the driving of no external force, and the filter unit is reasonable in structure, stable in liquid discharge and low in cost.

Further, drain pipe 2 include that the level form is fixed the hollow tube 21 at stock chest 1 notch department, hollow tube 21 runs through the shaft of column filter unit 4 and constitutes normal running fit with filter unit 4, the pipe section downwardly extending that hollow tube 21 is located filter unit 4 shaft has feed liquor pipe 22, hollow tube 21 has drain pipe 23 at the side downwardly extending of stock chest 1, drain pipe 23 is located the fluid-discharge tank 5 of stock chest 1 side. As shown in fig. 1, the hollow tube 21 not only conducts the liquid discharge pipe 2, but also realizes the reliable installation of the filtering unit 4, and the hollow tube 21 is also used as the rotation center of the filtering unit 4, so that the filtering unit 4 can rotate around the hollow tube 21 under the pushing of flowing slurry, thereby preventing the fiber in the slurry from adhering to the surface of the filter screen of the filtering unit 4 and ensuring the stability of the filtering effect of the filtering unit 4.

Furthermore, the liquid discharge pipe 2 further includes a liquid pumping pipe 24, the upper end of the liquid pumping pipe 24 is communicated with the liquid outlet pipe 23, the communication position of the liquid pumping pipe 24 and the liquid outlet pipe 23 is lower than the liquid inlet end of the liquid inlet pipe 22, and the liquid pumping device 3 is disposed on the liquid pumping pipe 24. As shown in fig. 1, the arrangement of the liquid pumping pipe 24 enables the liquid pumped and discharged by the liquid pumping device 3 and the siphon liquid flow to be discharged from different pipelines, and under the condition that the siphon liquid flow can be effectively established, the maximum liquid discharge efficiency of the liquid discharge pipeline 2 can be increased, and the productivity is improved.

Preferably, the liquid level sensor 11 is a liquid level switch, the liquid level sensor 11 is connected to a control circuit of the liquid pumping device 3, and the liquid level sensor 11 is connected in series with the liquid pumping device 3, and the step B includes the following steps: b1 when the liquid level sensor 11 collects the signal, the control circuit is conducted, and the liquid pumping device 3 is started to work; b2 when the liquid level sensor 11 does not collect a signal, the control circuit is disconnected, and the liquid pumping device 3 is closed. The circuit is simple and convenient to control, a good using effect can be achieved under the condition that the input cost is low, and the installation and maintenance cost is low.

Preferably, as shown in fig. 2, the liquid drainage pipeline 2 includes a bleed air pipe 25, one end of the bleed air pipe 25 is communicated with the liquid outlet pipe 23 or the pipe section of the hollow pipe 21 located outside the filter unit 4, and the other end is open, and the bleed air valve 6 is disposed on the bleed air pipe 25. Thus, when the siphon flow in the drain 2 is maintained, the bleed valve 6 is opened to allow air to enter the drain 2 from the bleed pipe 25, and the siphon flow can be terminated when the pressure in the drain 2 does not meet the siphon condition.

Claims

1. A liquid discharge control method of a bleaching system comprises the following steps:

(A) a liquid level sensor (11) is arranged on the wall of a slurry tank (1) in a slurry floating system, the liquid level sensor (11) is arranged at a water level height warning value K1, and K1 is close to the notch of the slurry tank (1);

(B) a liquid pumping device (3) is arranged on a liquid discharge pipeline (2) for discharging filtrate in the slurry tank (1), and a liquid level sensor (11) collects water level height information in the slurry tank (1) to monitor the water level height in the slurry tank (1); a filtering unit (4) is arranged at the notch of the slurry tank (1), a liquid inlet of the liquid drainage pipeline (2) is positioned in the area enclosed by the filter screen of the filtering unit (4), a liquid outlet of the liquid drainage pipeline extends out of the slurry tank (1), and a liquid inlet of the liquid drainage pipeline (2) is higher than the liquid outlet;

when the water level height in the slurry tank (1) is greater than K1, the liquid pumping device (3) is started and discharges liquid from the slurry tank (1) to the outside, and when the water level height in the slurry tank (1) is less than or equal to K1, the liquid pumping device (3) is in a standby state;

drainage tube (2) including hollow tube (21) that the level form was fixed in dressing trough (1) notch department, hollow tube (21) run through the shaft of column filter unit (4) and constitute normal running fit with filter unit (4), the pipeline section that hollow tube (21) are located filter unit (4) shaft extends downwards has feed liquor pipe (22), hollow tube (21) have drain pipe (23) in the side downwardly extending of dressing trough (1), drain pipe (23) are located in drainage trough (5) of dressing trough (1) side.

2. The method of claim 1 for controlling the drainage of a pulp bleaching system, comprising: the K1 is more than or equal to the depth of the stock tank (1)

。

3. The method of claim 1 for controlling the drainage of a pulp bleaching system, comprising: liquid discharge pipe (2) still include pump liquid pipe (24), the upper end and drain pipe (23) intercommunication and pump liquid pipe (24) of pump liquid pipe (24) are less than the inlet end of feed liquor pipe (22) with the intercommunication department of drain pipe (23), pump liquid device (3) are located on pump liquid pipe (24).

4. The method for controlling drainage of a bleaching system according to any one of claims 1-3, characterized in that: liquid level sensor (11) be the liquid level switch, liquid level sensor (11) link to each other and liquid level sensor (11) and pump liquid device (3) the control circuit of liquid device (3) establish ties, step B include following step:

(B1) when the liquid level sensor (11) collects a signal, the control circuit is conducted, and the liquid pumping device (3) is started to work;

(B2) when the liquid level sensor (11) does not acquire a signal, the control circuit is disconnected, and the liquid pumping device (3) is closed.