Negative pressure generation system for ore pulp filtration and control method thereof

Abstract

The invention discloses a negative pressure generation system for ore pulp filtration and a control method thereof, and belongs to the technical field of filtration. The front end of the vacuum filtering equipment is connected with the thickener, and the rear end is connected with a connector through a vacuum pipe. The connector is connected with a water tank through a negative pressure generation auxiliary pipe. The water tank is connected with a water pump driven by a variable-frequency and variable-speed motor. And the outer end of the horizontal section of the negative pressure generation auxiliary pipe is connected with one side of the water tank. The upper end of the vertical section of the negative pressure generation auxiliary pipe is connected with a water supplementing pipe and an exhaust pipe. The upper end of the water tank is provided with an air pressure communicating pipe. The water tank is further provided with a liquid level meter used for sensing and measuring the water level in the water tank. The system further comprises a controller used for collecting water level data in the water tank and controlling the variable-frequency and variable-speed motor. A higher vacuum degree is obtained by utilizing local vacuum generated by liquid height difference, so that the energy consumption of a system is reduced, the working efficiency of vacuum filtering equipment is improved, and the water content of a filter cake is reduced.

Description

Technical Field

[0001] The invention relates to a negative pressure generating system for pulp filtration and a control method of the system, belonging to the technical field of filtration. Background Art

[0002] Common methods for slurry solid-liquid separation include sedimentation, filtration, filter pressing, and centrifugation. Among them, vacuum filtration is a widely used method for slurry solid-liquid separation. Vacuum filtration is an operation that uses vacuum negative pressure as a driving force to achieve solid-liquid separation. Under the action of vacuum negative pressure (0.05-0.10MPa), the mixture of solid and liquid is pumped away through the filter medium (such as filter cloth), while the solid particles are retained by the filter medium, thereby achieving liquid and solid separation.

[0003] In the field of slurry solid-liquid separation, common vacuum filtration equipment includes disc vacuum filters and belt vacuum filters. Most of the above equipment uses jet vacuum pumps to create vacuum negative pressure. The working principle of the jet vacuum pump is to use a high-speed jet through a nozzle to extract the gas in the container to obtain a vacuum. In production applications, this type of equipment has defects such as high energy consumption, high wear and tear, and many failure points. In addition, the maximum vacuum manufacturing capacity of conventional jet vacuum pumps is 0.10Mpa, which to a certain extent limits the working efficiency of vacuum filtration equipment and the moisture content of filter cakes.

[0004] For example, the Chinese invention patent application with publication number CN108481811817A discloses a "disc-type double vacuum filter drain device", which includes a drain tank body, which is arranged above the ground at a preset height and fixed by a base support, and a water seal box is arranged below the base; an inlet flange is arranged in the middle of the drain tank body, and the inlet flange is used to connect with the double vacuum filter; a vacuum flange is arranged at the top of the drain tank body, and the vacuum flange is used to connect with a vacuum pump; a discharge flange is arranged at the bottom of the drain tank body, and the discharge flange is connected to the water seal box through a water pipe. The preset height can be in the range of 10m to 15m. It adopts a relatively simplified structure and is directly connected to the disc double vacuum filter and the vacuum pump at the construction site, which greatly saves the construction area occupied by the equipment required to complete the dehydration work at the construction site; and, by observing the vacuum instrument panel and adjusting the pressure relief valve, it is possible to maintain the vacuum difference in the symmetrical vacuum area of ​​the drainage tank. Finally, when the filtration is completed, the liquid and moisture in the pipeline can flow back to the water seal box, which greatly reduces the number of equipment maintenance times during the dehydration work, improves the dehydration efficiency, and extends the overall service life of the device.

[0005] In the published invention patent application, the slurry flow and the lifting of the liquid in the water seal box both rely on the power of a vacuum pump, which has defects such as high energy consumption and large wear, and the vacuum degree manufacturing capacity of the vacuum pump is limited.

[0006] The belt vacuum filter has the following main disadvantages: First, the vacuum pump used in the belt vacuum filter has limited ability to create negative pressure, resulting in high residual moisture in the filter cake and poor indicators; Second, the production process of the belt vacuum filter press is relatively complicated, so the equipment cost is high and requires a high capital investment; Third, the belt vacuum filter press requires professional technicians to operate and maintain it. Improper use may cause equipment damage or reduced efficiency; Fourth, the belt vacuum filter press may have some unexpected technical failures when the ambient temperature, humidity, pressure, etc. change greatly. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a negative pressure generating system for slurry filtration and a control method thereof. Firstly, a local vacuum generated by a liquid height difference is utilized to obtain a higher vacuum degree, thereby reducing system energy consumption, improving the working efficiency of vacuum filtration equipment, and reducing the moisture content of filter cakes; secondly, a relatively accurate negative pressure generating auxiliary pipe size is obtained through mathematical calculation according to the filtrate output of the vacuum filtration equipment and the designed vacuum degree.

[0008] The technical solution of the present invention is as follows: A negative pressure generating system for slurry filtration comprises a vacuum filtering device, the front end of which is used to connect to a thickener, and the rear end of which is connected to a vacuum tube. The system also comprises a connector connected to the vacuum tube on one side; the connector is connected to a water tank through a negative pressure generating auxiliary tube; the water tank is connected to a water pump driven by a variable frequency speed regulating motor through a water pump water inlet pipe with a water pump water inlet control valve; the negative pressure generating auxiliary tube is L-shaped as a whole, the top of the vertical section of which is connected to the bottom of the connector, and the outer end of the horizontal section is connected to one side of the water tank; the upper end of the vertical section of the negative pressure generating auxiliary tube is connected to a water supply pipe with a water supply control valve and an exhaust pipe with an exhaust control valve; a vertically arranged air pressure connecting pipe with an air pressure connecting control valve is installed at the upper end of the water tank; a liquid level gauge for sensing and measuring the water level in the water tank is also installed on the water tank; the system also comprises a controller for collecting water level data in the water tank and for controlling the variable frequency speed regulating motor.

[0009] Preferably, a water tank drain pipe with a water tank drain control valve is also connected to the bottom side or lower end of the water tank.

[0010] Preferably, the diameter and height of the negative pressure generating auxiliary tube are calculated and determined according to the following formula: ; In the formula —Diameter of the auxiliary pipe for generating negative pressure, m; K0—redundancy coefficient; μ —The flow rate of the liquid in the auxiliary pipe generating negative pressure is designed to be 0.1~0.2m / s; V—Vacuum filtration equipment filtrate output, m 3 / s; in ; Where Q is the solid processing capacity per unit time of vacuum filtration equipment, t / s; R1—Liquid-to-solid ratio of the suspended slurry fed into the vacuum filtration equipment; R2—liquid-to-solid ratio of the water-containing filter cake produced by the vacuum filtration equipment; ρ —Filtrate density, t / m 3 ; ; Where H is the height difference from the lower edge of the exhaust pipe to the highest liquid level in the water tank, m; K1—redundancy coefficient; h—the height of a water column supported by ten standard atmospheres, 103.4m / Mpa; P—vacuum degree required by vacuum filtration equipment design, MPa; ρ 0—Clean water density, t / m 3 ; ρ —Filtrate density, t / m 3 .

[0011] The control method of the negative pressure generating system for slurry filtration is controlled according to the following steps: Step 1: Close the water tank drainage control valve and the water pump inlet control valve, open the exhaust control valve, the air pressure connection control valve and the water supply control valve, and add clean water to the negative pressure generating auxiliary pipe and the water tank through the water supply pipe; Step 2: When the air pressure connecting pipe begins to overflow, close the air pressure connecting control valve; when the exhaust pipe begins to overflow, close the water supply control valve and the exhaust control valve in sequence; Step three: After the water replenishment is completed, start the water pump, open the water pump water inlet control valve and the air pressure connection control valve in sequence, and the vacuum filtration equipment performs solid-liquid separation operations; during the solid-liquid separation operation, the controller adjusts the operating frequency of the variable frequency speed regulation motor through the data detected in real time by the liquid level meter to control the water pump's discharge volume to ensure that the liquid level in the water tank is within the set range.

[0012] Compared with the prior art, the beneficial effects of the present invention are: First, the present invention utilizes the local vacuum generated by the height difference of the liquid at the upper and lower ends of the negative pressure auxiliary tube and the effect of atmospheric pressure to achieve solid-liquid separation and rapid drainage. Through the negative pressure vacuum generating system of the present invention, a vacuum degree that greatly exceeds conventional technology can be obtained, thereby significantly improving the working efficiency of the vacuum filtration equipment and reducing the moisture content of the filter cake. The entire system only needs one water pump to discharge the filtrate, and the operating energy consumption can be reduced by more than 50% compared with the prior art.

[0013] Second, in practical applications, the present invention can satisfy the simultaneous operation of multiple sets of vacuum filtration equipment, realizing a "one-to-many" operation mode, with low investment cost, low operating energy consumption, few system failure points, and easy control and operation.

[0014] Third, the present invention can meet the needs of simultaneous operation of multiple vacuum filtration equipment by increasing the diameter of the auxiliary pipe for generating negative pressure, which can effectively reduce equipment failure points and maintenance workload, and facilitate centralized production management.

[0015] Fourthly, the present invention can make full use of the height difference of mine shaft or mountain terrain for construction, and the whole system has simple configuration and lower construction cost.

[0016] Fifth, if the size of the auxiliary tube for generating negative pressure is determined only by experience, the negative pressure will be too low, affecting the use effect of the vacuum filtration equipment, or the negative pressure will be too small to meet the needs of multiple vacuum filtration equipment running at the same time; or the negative pressure will be too high, damaging the filter components such as the belt or ceramic plate of the vacuum filtration equipment. On the other hand, once it is built, it is extremely difficult to correct the size of the auxiliary tube for generating negative pressure according to the actual operation situation, and it will cause a lot of capital and manpower investment. The present invention obtains a relatively accurate size of the auxiliary tube for generating negative pressure through mathematical calculation according to the filtrate output of the vacuum filtration equipment and the designed vacuum degree. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the system of the present invention; Figure 2 It is a structural schematic diagram of the top of the negative pressure generating auxiliary pipe and its connecting parts in the embodiment of the system of the present invention; Figure 3 Schematic diagram of the structure of the water tank and its connecting parts in the system embodiment of the present invention.

[0018] Description of reference numerals: 1. Connector; 2. Negative pressure generating auxiliary pipe; 3. Water supply pipe; 31. Water supply control valve; 4. Exhaust pipe; 41. Exhaust control valve; 5. Water tank; 51. Air pressure connecting pipe; 52. Air pressure connecting control valve; 53. Water tank drain pipe; 54. Water tank drain control valve; 6. Water pump; 61. Water pump inlet pipe; 62. Water pump inlet control valve; 63. Water pump drain pipe; 7. Liquid level meter; 8. Vacuum filtration equipment; 81. Vacuum tube. DETAILED DESCRIPTION

[0019] In order to make those skilled in the art better understand, the present invention is further described below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work should belong to the scope of protection of the present invention. 1. An embodiment of a negative pressure generating system for slurry filtration according to the present invention.

[0020] like Figure 1 , Figure 2 and Figure 3 The embodiment of the negative pressure generating system for pulp filtration of the present invention comprises a vacuum filtration device 8, the front end of which is used to connect to a thickener, and the rear end is connected to a vacuum tube 81. After the pulp is concentrated by the thickener (for example, the pulp concentration is concentrated to about 50%), it enters the vacuum filtration device 8 for vacuum filtration.

[0021] The system also includes a connector 1 in the form of a sealed container connected to the vacuum tube 81. The connector 1 is made of iron plate welding and is generally in the shape of a cuboid. One side of the connector 1 is connected to the vacuum tube 81, and the connector 1 is also connected to a water tank 5 through a negative pressure generating auxiliary pipe 2. The outlet side of the water tank 5 is connected to a water pump 6 through a water pump inlet pipe 61 with a water pump inlet control valve 62. The water pump 6 is connected to a water pump drain pipe 63. The water pump 6 uses a variable frequency speed regulating motor.

[0022] Among them, the negative pressure generating auxiliary pipe 2 is made of seamless steel pipe, and is "L" shaped as a whole. The top of its vertical section is connected to the bottom of the connector 1, and the outer end of the horizontal section is connected to one side of the water tank 5.

[0023] like Figure 2 The upper end of the vertical section of the negative pressure generating auxiliary pipe 2 is connected to a water supply pipe 3 with a water supply control valve 31 and an exhaust pipe 4 with an exhaust control valve 41. The water supply pipe 3 is used to add clean water to the negative pressure generating auxiliary pipe 2 to form a negative pressure differential at the initial stage of operation. The exhaust pipe 4 is used to exhaust the air in the pipe when adding clean water to the negative pressure generating auxiliary pipe 2 to ensure that the system is full of clean water. The water pump 6 is used to promptly pump out the clean water in the negative pressure generating auxiliary pipe 2 to form a liquid level difference.

[0024] like Figure 3 The water tank 5 is generally made of iron plates welded and has a rectangular shape. An air pressure connecting pipe 51 with an air pressure connecting control valve 52 is installed at the upper end of the water tank 5. The air pressure connecting pipe 51 is arranged vertically. The water tank 5 is also equipped with a liquid level meter 7 located directly above the air pressure connecting pipe 51 and used for sensing and measuring the water level in the water tank 5. The liquid level meter 7 is generally a radar level meter, a laser level meter or an ultrasonic level meter.

[0025] The bottom side or lower end of the water tank 5 is also connected to a water tank drain pipe 53 with a water tank drain control valve 54 .

[0026] The embodiment of the system of the present invention further comprises a controller for collecting water level data in the water tank 5 through the liquid level meter 7 and for controlling the variable frequency speed regulating motor.

[0027] Among them, the diameter (inner diameter) and height of the negative pressure generating auxiliary pipe 2 are related to the filtrate output of the vacuum filtration equipment and the designed vacuum degree, and the specific values ​​are calculated and determined according to Formula 1 and Formula 2.

[0028] Formula 1: ; In the formula —Diameter of the auxiliary pipe for generating negative pressure, m; K0—redundancy coefficient, generally 1.1; μ —The flow rate of the liquid in the auxiliary pipe generated by negative pressure is generally designed to be 0.1~0.2m / s; V—Vacuum filtration equipment filtrate output, m 3 / s; in ; Q—solid processing capacity per unit time of vacuum filtration equipment, t / s; R1—Liquid-to-solid ratio of the suspended slurry fed into the vacuum filtration equipment; R2—liquid-to-solid ratio of the water-containing filter cake produced by the vacuum filtration equipment; ρ —Filtrate density, t / m 3 .

[0029] Formula 2: ; Where H is the height difference from the lower edge of the exhaust pipe at the top of the negative pressure generating auxiliary pipe to the highest liquid level in the water tank, m; (the highest liquid level in the water tank is the lower edge of the top plate of the water tank 5) K1—Redundancy coefficient, generally 1.1~1.2; h—the height of a water column supported by ten standard atmospheres, 103.4m / Mpa; P—vacuum degree required by vacuum filtration equipment design, MPa; ρ 0—Clean water density, t / m 3 ; ρ —Filtrate density, t / m 3 .

[0030] The vertical and vertical arrangement mentioned in the present invention refer to the direction being perpendicular to the horizontal plane. 2. Embodiment of the negative pressure generating system control method for slurry filtration according to the present invention.

[0031] Step 1: Close the water tank drain control valve 54 and the water pump inlet control valve 62, and open the exhaust control valve 41, the air pressure connection control valve 52 and the water supply control valve 31 in sequence, and add clean water to the negative pressure generating auxiliary pipe 2 and the water tank 5 through the water supply pipe 3; Step 2: When the air pressure connecting pipe 51 starts to overflow, the air pressure connecting control valve 52 is closed; when the exhaust pipe 4 starts to overflow, the water supply control valve 31 and the exhaust control valve 41 are closed in sequence; The water replenishment operation into the negative pressure generating auxiliary pipe 2 is completed through step 1 and step 2; Step 3: After the water replenishment is completed, the water pump 6 is started in sequence, and the water pump water inlet control valve 62 and the air pressure connection control valve 52 are opened. At this time, a vacuum negative pressure is formed inside the connector 1, and the vacuum filtering device 8 connected thereto performs a solid-liquid separation operation.

[0032] During the solid-liquid separation process, the filtrate enters the connector 1 , the negative pressure generating auxiliary pipe 2 , the water tank 5 and the water pump 6 in sequence through the vacuum tube 81 , and is finally discharged through the water pump drain pipe 63 .

[0033] During the solid-liquid separation operation, the liquid level meter 7 detects data and the controller adjusts the operating frequency in a timely manner to reasonably control the discharge volume of the water pump 6 to ensure that the liquid level in the water tank 5 is within a certain set range (for example, the liquid level in the water tank 5 is not lower than the upper edge of the horizontal section of the negative pressure generating auxiliary pipe 2 and is not lower than the upper edge of the water pump inlet pipe 61), thereby obtaining a continuous and stable vacuum negative pressure effect.

[0034] When the vacuum filtration equipment is shut down for a short time, the air pressure connection control valve 52, the water pump water inlet control valve 62, and the water pump 6 can be closed. When it needs to be shut down for a long time, first close the air pressure connection control valve 52, the water pump water inlet control valve 62, and the water pump 6, and open the exhaust control valve 41 and the water tank drainage control valve 54 in sequence, and the negative pressure auxiliary pipe 2 and the clean water in the water tank 5 are discharged through the water tank drainage pipe 53. When the vacuum filtration equipment needs to be started, repeat the above steps. 3. Field application examples of the present invention.

[0035] A copper ore beneficiation plant processes 1,000 tons of raw ore per day, of which the concentrate output is 200 tons per day and the tailings output is 800 tons per day. During the production process, the concentrate and tailings slurries are concentrated by their respective thickeners, and the slurry concentration reaches 50%, and then fed into five 90m 2 Vacuum filtration is performed in the ceramic filter, with one filter for concentrate and four for tailings. The ceramic filter works for 6 hours per shift, the filter plate is cleaned for 2 hours, the total operating time is 18 hours per day, the ore processing capacity is 11.1 tons / hour, and the moisture content of the concentrate and tailings filter cakes after filtration is about 15%. Each ceramic filter is equipped with a vacuum jet system for creating vacuum negative pressure. The system includes a vacuum jet pump, a water tank, a pipeline, etc. The jet pump has a power of 22kw / unit, and each system costs 80,000 yuan. The vacuum degree manufacturing capacity of the vacuum jet system is about 0.1Mpa when it is running.

[0036] In order to further optimize production indicators, the mine used the system and its control method of the present invention in an idle shaft near the concentrator under confidentiality conditions, replacing the original five vacuum jet systems. The specific parameters are as follows: the negative pressure auxiliary pipe model is 377×8mm seamless steel pipe; the height difference between the top of the negative pressure auxiliary pipe 3 and the liquid level of the water tank 5 is 35m; the water pump power is 45kw. (1) The diameter of the negative pressure auxiliary pipe is calculated according to the formula ; In the formula —Diameter of the auxiliary pipe for negative pressure generation, m; K0—redundancy coefficient, take 1.1; μ —The flow rate of liquid in the auxiliary pipe generated by negative pressure is designed to be 0.15m / s; V—The filtrate output of 5 ceramic filters, m 3 / s; , where Q is the solid processing capacity per unit time of 5 ceramic filters, 55.5 / 3600=0.0154t / s; R1 is the liquid-solid ratio of the slurry fed into the ceramic filter, 1:1; R2 is the liquid-solid ratio of the filter cake produced by the ceramic filter, 15:85; ρ —Filtrate density, 1.0t / m 3 ; Calculate V to be 0.0127m 3 / s.

[0037] Calculation results: =0.361m; According to the calculation results, the inner diameter of the negative pressure generating auxiliary pipe is determined to be 361mm, and it is made of 377×8mm standard seamless steel pipe.

[0038] (2) The height of the auxiliary pipe for generating negative pressure is calculated according to the formula ; Where H is the height difference from the lower edge of the exhaust pipe at the top of the negative pressure generating auxiliary pipe to the highest liquid level in the water tank, m; K1—redundancy coefficient, take 1.1; h—the height of a water column that can be supported by ten standard atmospheric pressures, take 103.4m / Mpa; P—the maximum vacuum degree designed for the operation of the ceramic filter, 0.30Mpa; ρ 0—Clean water density, 1.0t / m 3 ; ρ —Filtrate density, 1.0t / m 3 .

[0039] Calculation results: H=1.1×103.4×0.30×(1.0 / 1.0)=34.12m.

[0040] According to the calculation results, the height difference from the lower edge of the exhaust pipe at the top of the negative pressure generating auxiliary pipe to the highest liquid level in the water tank is determined to be 35m.

[0041] The mine adopts the vacuum negative pressure manufacturing system and its control method of the present invention, making full use of the idle shafts of the mine and greatly reducing the construction cost. The comparison between the present invention and conventional technology after construction and commissioning is as follows: (1) The total investment of the system of the present invention is 100,000 yuan, which reduces the investment cost by 75% compared with conventional technology; (2) After the system of the present invention is put into use, the vacuum degree reaches 0.30Mpa, which is 200% higher than that of conventional technology; (3) After the vacuum degree is improved, the processing capacity of a single ceramic filter reaches 14.81 tons / hour, the processing capacity is increased by 30%, and the number of tailings ceramic filters in operation is reduced from four to three; (4) After the vacuum degree is improved, the moisture content of the filter cake of the ceramic filter is about 12%, which is about 3% lower than the original index, significantly reducing the subsequent automobile transportation cost of concentrate and tailings; (5) The operating power of the vacuum manufacturing system is reduced from 110kw to 45kw, reducing energy consumption by 60%. By adopting the present invention, the mine increases its annual economic benefits by more than 1 million yuan.

[0042] Although the present invention has been described in detail by reference to the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A negative pressure generating system for pulp filtration, comprising a vacuum filtration device (8), wherein the front end of the vacuum filtration device (8) is used to connect to a thickener, and the rear end is connected to a vacuum tube (81), characterized in that: The system further comprises a connector (1) connected to the vacuum tube (81) on one side; the connector (1) is connected to a water tank (5) via a negative pressure generating auxiliary tube (2); the water tank (5) is connected to a water pump (6) driven by a variable frequency speed regulating motor via a water pump water inlet tube (61) having a water pump water inlet control valve (62); the negative pressure generating auxiliary tube (2) is L-shaped as a whole, with the top end of the vertical section connected to the bottom end of the connector (1) and the outer end of the horizontal section connected to one side of the water tank (5); The upper end of the vertical section of the pipe (2) is connected to a water supply pipe (3) with a water supply control valve (31) and an exhaust pipe (4) with an exhaust control valve (41); the upper end of the water tank (5) is provided with a vertically arranged air pressure communication pipe (51) with an air pressure communication control valve (52); the water tank (5) is also provided with a liquid level meter (7) for sensing and measuring the water level in the water tank (5); the system further comprises a controller for collecting water level data in the water tank (5) and for controlling the variable frequency speed regulating motor.

2. The negative pressure generating system for slurry filtration according to claim 1, characterized in that: The bottom side or lower end of the water tank (5) is also connected to a water tank drain pipe (53) having a water tank drain control valve (54).

3. The negative pressure generating system for pulp filtration according to claim 1, characterized in that The diameter and height of the negative pressure generating auxiliary tube (2) are calculated and determined according to the following formula: ； In the formula —Diameter of the auxiliary pipe for generating negative pressure, m; K0—redundancy coefficient; μ —The flow rate of the liquid in the auxiliary pipe generating negative pressure is designed to be 0.1~0.2m / s; V—Vacuum filtration equipment filtrate output, m 3 / s; in ; Where Q is the solid processing capacity per unit time of vacuum filtration equipment, t / s; R1—Liquid-to-solid ratio of the suspended slurry fed into the vacuum filtration equipment; R2—liquid-to-solid ratio of the water-containing filter cake produced by the vacuum filtration equipment; ρ —Filtrate density, t / m 3 ; ； Where H is the height difference between the lower edge of the exhaust pipe (4) and the highest liquid level in the water tank (5), m; K1—redundancy coefficient; h—the height of a water column supported by ten standard atmospheres, 103.4m / Mpa; P—vacuum degree required by vacuum filtration equipment design, MPa; ρ 0—Clean water density, t / m 3 ; ρ —Filtrate density, t / m 3 .

4. The control method of the negative pressure generating system for pulp filtration according to claim 1, 2 or 3, characterized in that Follow these steps to control: Step 1: close the water tank drainage control valve (54) and the water pump water inlet control valve (62), open the exhaust control valve (41), the air pressure connection control valve (52) and the water supply control valve (31), and add clean water to the negative pressure generating auxiliary pipe (2) and the water tank (5) through the water supply pipe (3); Step 2: When the air pressure connecting pipe (51) starts to overflow, the air pressure connecting control valve (52) is closed; when the exhaust pipe (4) starts to overflow, the water supply control valve (31) and the exhaust control valve (41) are closed in sequence; Step 3: After the water replenishment is completed, the water pump (6) is started in sequence, the water pump water inlet control valve (62) and the air pressure connection control valve (52) are opened, and the vacuum filtration equipment (8) performs a solid-liquid separation operation; during the solid-liquid separation operation, the controller adjusts the operating frequency of the variable frequency speed regulating motor through the data detected in real time by the liquid level meter (7) to control the water discharge volume of the water pump (6) to ensure that the liquid level in the water tank (5) is within a set range.

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