Bidirectional cross-flow washing and air-drying vertical filter press and working method thereof

Abstract

The invention discloses a bidirectional cross-flow washing and air-drying vertical filter press and a working method thereof, and belongs to the technical field of vertical filter presses. Aiming at the defects of poor working condition adaptability, low effective thickness of a filter cake, non-uniform washing and air-drying effects, high energy consumption and maintenance cost and the like of the traditional vertical filter press adopting a single-layer filter cloth and rubber diaphragm structure, the invention cancels a rubber diaphragm, adopts a diaphragm-free structure in which the filter cake is clamped by double-layer filter cloth, and designs a bidirectional cross-flow washing and air-drying process in a matched manner; by switching the opening and closing states of the pneumatic valve group, washing water and compressed air respectively enter from the back surfaces of the two layers of filter cloth, pass through the filter cake in two directions and then are discharged. According to the invention, the effective thickness of the filter cake is increased, the productivity is synchronously improved, the washing effect and the air drying effect are improved under the same condition, the adaptability of the equipment to high-temperature, strong-acid and strong-alkali working conditions is enhanced, the manufacturing cost and the maintenance difficulty are reduced, online regeneration of the filter cloth can be realized, and the device is suitable for solid-liquid separation treatment of various materials.

Description

Technical Field

[0001] This invention belongs to the field of filter press technology, specifically a vertical filter press with bidirectional flow washing and air drying and its working method. Background Technology

[0002] Vertical filter presses, also known as fully automatic filter cloth filter presses, utilize high-pressure extrusion and high-pressure air drying to expel filter material from slurry, achieving solid-liquid separation. They simultaneously perform washing, dewatering, and air-drying functions, and are widely used in solid-liquid separation operations for materials such as nickel concentrate, zinc oxide leaching solution, starch, and sludge. Traditional vertical filter presses use a single-layer filter cloth structure with an elastic rubber diaphragm above it. During operation, high-pressure water deforms the rubber diaphragm, thereby compressing the filter cake to achieve dewatering. This structure has several drawbacks, as follows: 1. When rubber diaphragms are exposed to high temperatures, strong acids or strong alkalis, they are prone to aging, cracking, holes and other failures, which increases maintenance and usage costs. In addition, frequent replacement of diaphragms requires disassembling a large number of fasteners, which is time-consuming and labor-intensive.

[0003] 2. The thickness of the rubber diaphragm itself and the height required for extrusion deformation will occupy the volume of the filter frame, resulting in a 10-20% reduction in the effective thickness of the filter cake layer, while increasing the total height of the filter press and manufacturing cost.

[0004] 3. During the extrusion of the rubber diaphragm, the large deformation in the middle of the diaphragm will push some of the filter cake to the periphery of the diaphragm, resulting in uneven thickness and density of the filter cake layer in different parts, and uneven filtration resistance. This phenomenon is particularly obvious when processing materials with good flowability.

[0005] 4. The rubber diaphragm blocks the flow path of the filtrate, allowing the slurry, high-pressure gas, and washing water to enter only through the inlet and flow out in one direction. Because the filtration resistance varies across different parts of the filter cake layer, the drying gas and washing water will preferentially flow out through the channels with the lowest resistance, resulting in uneven washing and drying of the filter cake. To improve the effect, the drying air volume, drying time, washing water volume, and washing time need to be increased, leading to increased energy and washing water consumption. For users with strict limitations on the total washing water volume and production energy consumption, they can only sacrifice washing and drying effects and downgrade the equipment.

[0006] Currently, there is no mature solution in existing technologies that combines diaphragm-free double-layer filter cloth with bidirectional flow process, which cannot fundamentally solve the above-mentioned technical pain points. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned problems in the prior art and provide a vertical filter press with bidirectional cross-flow washing and drying and its working method. This equipment adopts a diaphragm-free design and a bidirectional cross-flow process, effectively improving filtration efficiency, washing and drying effect, and adaptability to various operating conditions. The specific technical solution is as follows: A vertical filter press for bidirectional flow washing and drying includes a vertical filter press, a gas-liquid separation and discharge unit, and a power supply unit. The left and right sides of the vertical filter press are connected to a first main pipe and a second main pipe via pipelines.

[0008] The gas-liquid separation and discharge unit includes a gas-liquid separation tank and a filtrate tank; the inlet end of the gas-liquid separation tank is divided into two paths, one path is connected to the first main pipe through a second pneumatic valve, and the other path is connected to the second main pipe through a fourth pneumatic valve; the bottom outlet end of the gas-liquid separation tank is connected to the filtrate tank for collecting filtrate, and the top outlet is connected to the vent valve for discharging dried gas.

[0009] The power supply unit includes an air tank, an air compressor, a wash water pump, and a wash water tank. The outlet of the air compressor is connected to the air tank to provide compressed air to the system, and the outlet of the wash water tank is connected to the wash water pump to provide wash water to the system. The outlet of the air tank is connected to a fifth pneumatic valve, and the outlet of the fifth pneumatic valve is divided into two paths: one path connects to a third pneumatic valve and then to the second main pipe, and the other path connects to a first pneumatic valve and then to the first main pipe. The outlet of the wash water pump is connected to a sixth pneumatic valve, and the outlet of the sixth pneumatic valve is divided into three paths: one path connects to the fifth pneumatic valve and then to the air tank for air tank pressure regulation, one path connects to the third pneumatic valve and then to the second main pipe, and the other path connects to the first pneumatic valve and then to the first main pipe.

[0010] The vertical filter press of this invention eliminates the traditional rubber diaphragm structure. The filter structure includes a filter frame, filter cloth, pressure strip, connecting pipe, and hose. A first filter cloth is laid inside the first filter frame, and a second filter cloth is laid inside the second filter frame. A filter cake cavity is formed between the two layers of filter cloth. The filter cake is wrapped by the two layers of filter cloth and squeezed into the filter cake cavity along with the filter cloth. The feed inlet is opened on the side of the filter frame, connecting the filter cake cavity between the two layers of filter cloth, and is used to transport the material to be filtered into the filter cake cavity. A first pressure strip presses the joint between the first filter cloth and the first filter frame, and a second pressure strip presses the joint between the second filter cloth and the second filter frame. One end of the first connecting pipe is connected to the outer cavity of the second filter cloth, and the other end is connected to the first main pipe through the first hose, forming a flow channel for filtrate, wash water, and drying gas. One end of the second connecting pipe is connected to the outer cavity of the first filter cloth, and the other end is connected to the second main pipe through the second hose, forming another set of flow channels.

[0011] Preferably, the filter cloth is made of acid- and alkali-resistant, high-temperature-resistant polypropylene (PP) or polytetrafluoroethylene (PTFE).

[0012] A method for operating a vertical filter press with bidirectional flow washing and drying includes the following steps: Step 1: Feeding and filtration stage; close all pneumatic valves, start the feeding system, and the material enters the filter cake chamber between the first filter cloth and the second filter cloth from the feed inlet; the material is squeezed and shaped by the feeding pressure, and the filtrate flows out through the filter cloth through the first connecting pipe, the first hose, the first main pipe and the second connecting pipe, the second hose and the second main pipe, and finally forms a filter cake in the filter cake chamber; Step 2: Two-way flow washing stage; By switching the opening and closing state of the pneumatic valve group, the bottom-up or top-down washing mode is selected, and the washing water is controlled to enter from the back of one layer of filter cloth, pass through the filter cake and flow out from the other layer of filter cloth, and finally enter the gas-liquid separation tank through the corresponding main pipe and pneumatic valve, and the filtrate flows into the filtrate tank. Step 3: Two-way flow drying stage; By switching the opening and closing state of the pneumatic valve group, select the bottom-up or top-down drying mode, control the compressed air to enter from the back of one layer of filter cloth, pass through the filter cake and flow out from the other layer of filter cloth, and finally enter the gas-liquid separator through the corresponding main pipe and pneumatic valve, and the gas is discharged by the vent valve. Step 4: Unloading stage; After air drying is completed, turn on the vertical filter press, drag the first filter cloth and unload the filter cake to complete a complete work cycle.

[0013] The preferred bottom-up washing method is as follows: Open the second, third, and sixth pneumatic valves, and close the first, fourth, and fifth pneumatic valves; start the washing water pump, and the washing water flows out of the washing water tank, sequentially passing through the washing water pump, the sixth pneumatic valve, the third pneumatic valve, the second main pipe, the second flexible hose, the first filter cloth, the filter cake, the second filter cloth, the first connecting pipe, the first flexible hose, the first main pipe, and the first pneumatic valve, and enters the gas-liquid separation tank; the filtrate flows into the filtrate tank. Preferably, the top-to-bottom washing method is as follows: Open the first pneumatic valve, the fourth pneumatic valve, and the sixth pneumatic valve, and close the fifth pneumatic valve, the second pneumatic valve, and the third pneumatic valve; start the washing water pump, and the washing water flows out from the washing water tank, sequentially flowing through the washing water pump, the sixth pneumatic valve, the first pneumatic valve, the first main pipe, the first flexible hose, the second filter cloth, the filter cake, the first filter cloth, the second connecting pipe, the second flexible hose, the second main pipe, and the fourth pneumatic valve, and enters the gas-liquid separation tank, and the filtrate flows into the filtrate tank.

[0014] The preferred bottom-up air-drying method is as follows: Open the second, third, and fifth pneumatic valves, and close the sixth, fourth, and first pneumatic valves; start the air compressor, and the compressed air passes through the air tank, the fifth and third pneumatic valves, the second main pipe, the second hose, the first filter cloth, the filter cake, the second filter cloth, the first connecting pipe, the first hose, the first main pipe, and the first pneumatic valve, and enters the gas-liquid separator. The gas is discharged through the vent valve.

[0015] The preferred top-down air-drying method is as follows: Open the first pneumatic valve, the fourth pneumatic valve, and the fifth pneumatic valve, and close the sixth pneumatic valve, the second pneumatic valve, and the third pneumatic valve; start the air compressor, and the compressed air passes through the air tank, the fifth pneumatic valve, the first pneumatic valve, the first main pipe, the first hose, the second filter cloth, the filter cake, the first filter cloth, the second connecting pipe, the second hose, the second main pipe, and the fourth pneumatic valve, and enters the gas-liquid separator. The gas is discharged through the vent valve.

[0016] Preferably, the washing and drying sequence from bottom to top and from top to bottom, the duration of each cycle, and the number of cycles can be flexibly adjusted according to the characteristics of the material and the dehydration requirements.

[0017] Compared with the closest existing technology, the technical solution provided by the present invention has the following beneficial effects: 1. To address the shortcomings of traditional equipment where rubber diaphragms are prone to aging and failure, this invention replaces rubber diaphragms with double-layer acid and alkali resistant filter cloth, reducing equipment manufacturing costs. This invention significantly improves adaptability to high-temperature, strong acid, and strong alkali conditions, reduces downtime due to malfunctions, and lowers maintenance costs by more than 30%. The volume occupied by the original rubber diaphragm is filled with filter cake, and under the same plate and frame thickness, the effective thickness of the filter cake layer is increased by 10-20%, resulting in a simultaneous increase in equipment capacity. The double-layer filter cloth doubles the filtrate channel area, improving filtration efficiency by more than 20%.

[0018] 2. In view of the shortcomings of uneven washing and drying effects in traditional equipment, the present invention adopts a two-way flow process, which improves the washing effect by 10-20% and saves 10-15% of washing water consumption under the same conditions; improves the drying effect by 8-10% and saves 10-20% of air volume.

[0019] 3. Addressing the issue of poor filter cake uniformity in traditional equipment, this invention utilizes feeding extrusion and gas drying to dehydrate the filter cake. This results in similar extrusion pressure across different parts, uniform filter cake thickness and density, consistent filtration resistance, and greater adaptability to material flowability. Washing water and drying gas enter from the back of the filter cloth, blowing away tiny particles within the filter cloth pores, enabling online regeneration of the filter cloth and extending its service life. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the vertical filter press of the present invention; Figure 2 The filtration structure of the vertical filter press of this invention is as follows: Figure 1 Enlarged schematic diagram at point I; Figure 3 This is a structural diagram of a traditional diaphragm vertical filter press.

[0021] The components include: 1. Vertical filter press; 2. First pneumatic valve; 3. First main pipe; 4. Second pneumatic valve; 5. Third pneumatic valve; 6. Second main pipe; 7. Fourth pneumatic valve; 8. Exhaust valve; 9. Gas-liquid separator; 10. Filtration tank; 11. Fifth pneumatic valve; 12. Sixth pneumatic valve; 13. Air storage tank; 14. Air compressor; 15. Washing water pump; 16. Washing water tank; 17. Filter cake; 1-1 Hose; 1-2 First filter cloth; 1-3 First connecting pipe; 1-4 First filter frame; 1-5 First pressure strip; 1-6 Second filter cloth; 1-7 Second filter frame; 1-8 Second pressure strip; 1-9 Second connecting pipe; 1-10 Second hose; 1-11 Feed inlet. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: Bottom-up washing and drying method A vertical filter press for bidirectional flow washing and drying includes a vertical filter press 1, a gas-liquid separation and discharge unit, and a power supply unit. The left and right sides of the vertical filter press 1 are connected to a first main pipe 3 and a second main pipe 6 via pipelines. The gas-liquid separation and discharge unit includes a gas-liquid separation tank 9 and a filter tank 10; the inlet end of the gas-liquid separation tank 9 is divided into two paths, one path is connected to the first main pipe 3 through the second pneumatic valve 4, and the other path is connected to the second main pipe 6 through the fourth pneumatic valve 7; the bottom outlet end of the gas-liquid separation tank 9 is connected to the filter tank 10 for collecting the filter liquid, and the top outlet is connected to the vent valve 8 for discharging the dried gas; The power supply unit includes an air tank 13, an air compressor 14, a wash water pump 15, and a wash water tank 16. The outlet end of the air compressor 14 is connected to the air tank 13 to provide compressed air to the system, and the outlet end of the wash water tank 16 is connected to the wash water pump 15 to provide wash water to the system. The outlet end of the air tank 13 is connected to a fifth pneumatic valve 11, and the outlet end of the fifth pneumatic valve 11 is divided into two paths: one path is connected to a third pneumatic valve 5 and then connected to a second main pipe 6, and the other path is connected to a first pneumatic valve 2 and then connected to a first main pipe 3. The outlet end of the wash water pump 15 is connected to a sixth pneumatic valve 12, and the outlet end of the sixth pneumatic valve 12 is divided into three paths: one path is connected to the fifth pneumatic valve 11 and then connected to the air tank 13, one path is connected to the third pneumatic valve 5 and then connected to a second main pipe 6, and the other path is connected to the first pneumatic valve 2 and then connected to a first main pipe 3.

[0024] The vertical filter press 1 has a filtration structure including a filter frame, filter cloth, pressure bar, connecting pipe, and hose; a first filter cloth 1-2 is laid inside the first filter frame 1-4, and a second filter cloth 1-6 is laid inside the second filter frame 1-7, forming a filter cake cavity between the two layers of filter cloth. The filter cake 17 is wrapped by the two layers of filter cloth and squeezed into the filter cake cavity along with the filter cloth; the feed inlet 1-11 is located on the side of the filter frame, connecting the filter cake cavity between the two layers of filter cloth, and is used to convey the material to be filtered into the filter cake cavity; the first pressure bar 1-5 presses the first filter cloth 1-4 into place. At the joint between the second filter cloth 1-6 and the first filter frame 1-4, the second pressure strip 1-8 presses the joint between the second filter cloth 1-6 and the second filter frame 1-7; one end of the first connecting pipe 1-3 is connected to the outer cavity of the second filter cloth 1-6, and the other end is connected to the first main pipe 3 through the first flexible hose 1-1, forming a flow channel for filtrate, washing water, and drying gas; one end of the second connecting pipe 1-9 is connected to the outer cavity of the first filter cloth 1-2, and the other end is connected to the second main pipe 6 through the second flexible hose 1-10, forming another set of flow channels.

[0025] A method for operating a vertical filter press with bidirectional cross-flow washing and drying, employing a bottom-up washing and drying process, includes the following steps: Step 1: Feeding and Filtration Stage; Close all pneumatic valves and start the feeding system. The material enters the filter cake chamber between the first filter cloth 1-2 and the second filter cloth 1-6 from the feed inlet 1-11. The material is squeezed and shaped by the feeding pressure. The filtrate passes through the filter cloth and flows out through the first connecting pipe 1-3, the first hose 1-1, the first main pipe 3, the second connecting pipe 1-9, the second hose 1-10, and the second main pipe 6, and finally forms a filter cake 17 in the filter cake chamber. Step 2: Two-way flow washing stage; Open the second pneumatic valve 4, the third pneumatic valve 5, and the sixth pneumatic valve 12, and close the first pneumatic valve 2, the fourth pneumatic valve 7, and the fifth pneumatic valve 11; Start the washing water pump 15, and the washing water flows out from the washing water tank 16, and flows sequentially through the washing water pump 15, the sixth pneumatic valve 12, the third pneumatic valve 5, the second main pipe 6, the second hose 1-10, the first filter cloth 1-2, the filter cake 17, the second filter cloth 1-6, the first connecting pipe 1-3, the first hose 1-1, the first main pipe 3, and the first pneumatic valve 2, and enters the gas-liquid separator 9, and the filtrate flows into the filtrate tank 10; Step 3: Two-way cross-flow drying stage; Open the second pneumatic valve 4, the third pneumatic valve 5, and the fifth pneumatic valve 11, and close the sixth pneumatic valve 12, the fourth pneumatic valve 7, and the first pneumatic valve 2; Start the air compressor 14, and the compressed air enters the gas-liquid separator 9 through the air storage tank 13, the fifth pneumatic valve 11, the third pneumatic valve 5, the second main pipe 6, the second hose 1-10, the first filter cloth 1-2, the filter cake 17, the second filter cloth 1-6, the first connecting pipe 1-3, the first hose 1-1, the first main pipe 3, and the first pneumatic valve 2. The gas is discharged through the vent valve 8.

[0026] Step 4: Unloading stage; After air drying is completed, open the vertical filter press 1, drag the first filter cloth 1-2 and unload the filter cake 17 to complete a complete work cycle.

[0027] Example 2: Washing and drying method from top to bottom A method for operating a vertical filter press with bidirectional cross-flow washing and drying, employing a top-down washing and drying process, includes the following steps: Step 1: Feeding and Filtration Stage; Close all pneumatic valves and start the feeding system. The material enters the filter cake chamber between the first filter cloth 1-2 and the second filter cloth 1-6 from the feed inlet 1-11. The material is squeezed and shaped by the feeding pressure. The filtrate passes through the filter cloth and flows out through the first connecting pipe 1-3, the first hose 1-1, the first main pipe 3, the second connecting pipe 1-9, the second hose 1-10, and the second main pipe 6, and finally forms a filter cake 17 in the filter cake chamber. Step 2: Two-way flow washing stage; Open the first pneumatic valve 2, the fourth pneumatic valve 7, and the sixth pneumatic valve 12, and close the fifth pneumatic valve 11, the second pneumatic valve 4, and the third pneumatic valve 5; Start the washing water pump 15, and the washing water flows out from the washing water tank 16, and flows sequentially through the washing water pump 15, the sixth pneumatic valve 12, the first pneumatic valve 2, the first main pipe 3, the first flexible hose 1-1, the second filter cloth 1-6, the filter cake 17, the first filter cloth 1-2, the second connecting pipe 1-9, the second flexible hose 1-10, the second main pipe 6, and the fourth pneumatic valve 7, and enters the gas-liquid separator 9, and the filtrate flows into the filtrate tank 10; Step 3: Open the first pneumatic valve 2, the fourth pneumatic valve 7, and the fifth pneumatic valve 11, and close the sixth pneumatic valve 12, the second pneumatic valve 4, and the third pneumatic valve 5; start the air compressor 14, and the compressed air enters the gas-liquid separator 9 through the air storage tank 13, the fifth pneumatic valve 11, the first pneumatic valve 2, the first main pipe 3, the first hose 1-1, the second filter cloth 1-6, the filter cake 17, the first filter cloth 1-2, the second connecting pipe 1-9, the second hose 1-10, the second main pipe 6, and the fourth pneumatic valve 7, and the gas is discharged through the vent valve 8; Step 4: Unloading stage; After air drying is completed, open the vertical filter press 1, drag the first filter cloth 1-2 and unload the filter cake 17 to complete a complete work cycle.

[0028] Furthermore, the washing and drying sequence, duration, and number of cycles for both bottom-up and top-down washing and drying methods are not specifically specified, nor are the relevant pipeline configurations and routes specified. These can be adjusted according to actual working conditions, and similar technical changes should be within the scope of protection of this patent.

[0029] Please see Figure 1The vertical filter press system of the present invention takes the vertical filter press 1 as the core and is equipped with a gas-liquid separation and discharge unit and a power supply unit. The compressed air generated by the air compressor 14 is stored in the air storage tank 13, and the washing water in the washing water tank 16 is transported to the system through the washing water pump 15. By switching the opening and closing states of each pneumatic valve, bidirectional transportation of washing water and compressed air is realized.

[0030] Please see Figure 2 The core filtration structure of the vertical filter press 1 adopts a double-layer filter cloth design, with the filter cake 17 wrapped between the two layers of filter cloth. Filtrate, wash water, and compressed air can flow bidirectionally through the connecting pipes, hoses, and main pipe on both sides to complete the filtration, washing, and drying operations.

[0031] Please see Figure 3 Traditional vertical filter presses use a combination of a single-layer filter cloth and a rubber diaphragm. The filter cloth is laid inside the filter frame, and an elastic rubber diaphragm is placed on top of the filter cloth, secured to the top of the filter frame with fasteners. During operation, high-pressure water is injected into the cavity above the diaphragm, squeezing the diaphragm downwards and deforming it, which in turn squeezes the filter cake on the filter cloth to achieve dewatering. The thickness of the diaphragm itself and the deformation space occupy the volume of the filter frame, resulting in a 10-20% reduction in the effective thickness of the filter cake, thus limiting the equipment's capacity. During the diaphragm compression process, the deformation in the middle is large, and the filter cake is pushed to the sides, causing uneven filter cake thickness and density, resulting in large differences in filtration resistance. The diaphragm also blocks the bidirectional flow path of the filtrate, allowing only unidirectional flow of filtrate, washing water, and drying gas, leading to uneven washing and drying of the filter cake and higher energy and washing water consumption.

[0032] Compared to the traditional diaphragm vertical filter press shown in Figure 3, this invention achieves a 10-20% increase in effective filter cake thickness, a 10-20% increase in washing effect, and an 8-10% increase in air drying effect through a diaphragm-free double-layer filter cloth design and a bidirectional flow process. At the same time, it saves 10-15% of washing water and 10-20% of air volume, and significantly improves the equipment's ability to withstand harsh working conditions and ease of maintenance.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vertical filter press with bidirectional flow washing and air drying, characterized in that, It includes a vertical filter press (1), a gas-liquid separation and discharge unit, and a power supply unit. The left and right sides of the vertical filter press (1) are connected to the first main pipe (3) and the second main pipe (6) through pipelines. The gas-liquid separation and discharge unit includes a gas-liquid separation tank (9) and a filter tank (10); the inlet end of the gas-liquid separation tank (9) is divided into two paths, one path is connected to the first main pipe (3) through the second pneumatic valve (4), and the other path is connected to the second main pipe (6) through the fourth pneumatic valve (7); the bottom outlet end of the gas-liquid separation tank (9) is connected to the filter tank (10) for collecting the filter liquid, and the top outlet is connected to the vent valve (8) for discharging the dried gas; The power supply unit includes an air tank (13), an air compressor (14), a water pump (15), and a water tank (16). The outlet end of the air compressor (14) is connected to the air tank (13) to provide compressed air to the system. The outlet end of the water tank (16) is connected to the water pump (15) to provide washing water to the system. The outlet end of the air tank (13) is connected to the fifth pneumatic valve (11). The outlet end of the fifth pneumatic valve (11) is divided into two paths. One path is connected to the third pneumatic valve (5) and then connected to the second main pipe (6). The other path is connected to the first pneumatic valve (2) and then connected to the first main pipe (3). The outlet end of the water pump (15) is connected to the sixth pneumatic valve (12). The outlet end of the sixth pneumatic valve (12) is divided into three paths. One path is connected to the fifth pneumatic valve (11) and then connected to the air tank (13). One path is connected to the third pneumatic valve (5) and then connected to the second main pipe (6). The other path is connected to the first pneumatic valve (2) and then connected to the first main pipe (3).

2. A vertical filter press with bidirectional flow washing and air drying according to claim 1, characterized in that, The vertical filter press (1) has a filtration structure including a filter frame, filter cloth, pressure bar, connecting pipe, and hose; the first filter cloth (1-2) is laid inside the first filter frame (1-4), and the second filter cloth (1-6) is laid inside the second filter frame (1-7), forming a filter cake cavity between the two filter cloths. The filter cake (17) is wrapped by the two filter cloths and squeezed into the filter cake cavity along with the filter cloths; the feed inlet (1-11) is opened on the side of the filter frame, connecting the filter cake cavity between the two filter cloths, and is used to convey the material to be filtered into the filter cake cavity; the first pressure bar (1-5) presses the first filter cloth (1-2) and the second filter cloth (1-4) together. At the joint of the first filter frame (1-4), the second pressure strip (1-8) presses the joint of the second filter cloth (1-6) and the second filter frame (1-7) tightly; one end of the first connecting pipe (1-3) is connected to the outer cavity of the second filter cloth (1-6), and the other end is connected to the first main pipe (3) through the first flexible hose (1-1), forming a flow channel for filtrate, washing water and air-dried gas; one end of the second connecting pipe (1-9) is connected to the outer cavity of the first filter cloth (1-2), and the other end is connected to the second main pipe (6) through the second flexible hose (1-10), forming another set of flow channels.

3. A vertical filter press with bidirectional flow washing and air drying according to claim 1, characterized in that, The filter cloth is made of acid- and alkali-resistant, high-temperature-resistant polypropylene (PP) or polytetrafluoroethylene (PTFE).

4. The working method of a vertical filter press with bidirectional flow washing and air drying according to claim 2, characterized in that, Includes the following steps: Step 1: Feeding and filtration stage; close all pneumatic valves, start the feeding system, and the material enters the filter cake chamber between the first filter cloth (1-2) and the second filter cloth (1-6) from the feed port (1-11); the material is squeezed and shaped by the feeding pressure, and the filtrate flows out through the filter cloth through the first connecting pipe (1-3), the first hose (1-1), the first main pipe (3), the second connecting pipe (1-9), the second hose (1-10), and the second main pipe (6), and finally forms a filter cake (17) in the filter cake chamber; Step 2: Two-way flow washing stage; by switching the opening and closing state of the pneumatic valve group, the bottom-up or top-down washing mode is selected, and the washing water is controlled to enter from the back of one layer of filter cloth, pass through the filter cake (17) and flow out from the other layer of filter cloth, and finally enter the gas-liquid separator (9) through the corresponding main pipe and pneumatic valve, and the filtrate flows into the filtrate tank (10). Step 3: Two-way flow drying stage; By switching the opening and closing state of the pneumatic valve group, the bottom-up or top-down drying mode is selected. The compressed air is controlled to enter from the back of one layer of filter cloth, pass through the filter cake (17) and flow out from the other layer of filter cloth, and finally enter the gas-liquid separator (9) through the corresponding main pipe and pneumatic valve. The gas is discharged by the vent valve (8). Step 4: Unloading stage; After air drying is completed, open the vertical filter press (1), drag the first filter cloth (1-2) and unload the filter cake (17) to complete a complete work cycle.

5. The working method of a vertical filter press with bidirectional flow washing and air drying according to claim 4, characterized in that, The specific method of bottom-up washing in step 2 is as follows: Bottom-up washing: Open the second pneumatic valve (4), the third pneumatic valve (5), and the sixth pneumatic valve (12), and close the first pneumatic valve (2), the fourth pneumatic valve (7), and the fifth pneumatic valve (11); start the washing water pump (15), and the washing water flows out from the washing water tank (16), and flows through the washing water pump (15), the sixth pneumatic valve (12), the third pneumatic valve (5), the second main pipe (6), the second hose (1-10), the first filter cloth (1-2), the filter cake (17), the second filter cloth (1-6), the first connecting pipe (1-3), the first hose (1-1), the first main pipe (3), and the first pneumatic valve (2) in sequence, and enters the gas-liquid separator (9), and the filtrate flows into the filtrate tank (10).

6. The working method of a vertical filter press with bidirectional flow washing and air drying according to claim 4, characterized in that, The specific method of the top-down washing method in step 2 is as follows: Open the first pneumatic valve (2), the fourth pneumatic valve (7), and the sixth pneumatic valve (12), and close the fifth pneumatic valve (11), the second pneumatic valve (4), and the third pneumatic valve (5); start the washing water pump (15), and the washing water flows out from the washing water tank (16), and flows through the washing water pump (15), the sixth pneumatic valve (12), the first pneumatic valve (2), the first main pipe (3), the first hose (1-1), the second filter cloth (1-6), the filter cake (17), the first filter cloth (1-2), the second connecting pipe (1-9), the second hose (1-10), the second main pipe (6), and the fourth pneumatic valve (7) in sequence, and enters the gas-liquid separation tank (9), and the filtrate flows into the filtrate tank (10).

7. The working method of a vertical filter press with bidirectional flow washing and air drying according to claim 4, characterized in that, The specific method of bottom-up air drying in step 3 is as follows: Open the second pneumatic valve (4), the third pneumatic valve (5), and the fifth pneumatic valve (11), and close the sixth pneumatic valve (12), the fourth pneumatic valve (7), and the first pneumatic valve (2); start the air compressor (14), and the compressed air passes through the air storage tank (13), the fifth pneumatic valve (11), the third pneumatic valve (5), the second main pipe (6), the second hose (1-10), the first filter cloth (1-2), the filter cake (17), the second filter cloth (1-6), the first connecting pipe (1-3), the first hose (1-1), the first main pipe (3), and the first pneumatic valve (2) and enters the gas-liquid separator (9), and the gas is discharged through the vent valve (8).

8. The working method of a vertical filter press with bidirectional flow washing and air drying according to claim 4, characterized in that, The specific method of the top-down air drying method in step 3 is as follows: Open the first pneumatic valve (2), the fourth pneumatic valve (7), and the fifth pneumatic valve (11), and close the sixth pneumatic valve (12), the second pneumatic valve (4), and the third pneumatic valve (5); start the air compressor (14), and the compressed air passes through the air storage tank (13), the fifth pneumatic valve (11), the first pneumatic valve (2), the first main pipe (3), the first hose (1-1), the second filter cloth (1-6), the filter cake (17), the first filter cloth (1-2), the second connecting pipe (1-9), the second hose (1-10), the second main pipe (6), and the fourth pneumatic valve (7) and enters the gas-liquid separator (9), and the gas is discharged through the vent valve (8).

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