A closed loop cleaning system and method for belt press filter screens

Abstract

The application discloses a closed-loop cleaning system and method for a filter screen of a belt filter press, comprising a mounting frame, a filter screen, a controller, a dehydration assembly, an air permeability detection assembly, at least one cleaning assembly, and a circle counting assembly; the dehydration assembly is used for removing free water in the screen holes of the filter screen; the air permeability detection assembly is used for detecting the air permeability characteristic values of the filter screen before and after cleaning and transmitting the values to the controller; the cleaning assembly performs cleaning operations such as water flushing, brush roll washing, and dirt scraping and guiding on the filter screen based on the air permeability characteristic values of the air permeability detection assembly; the circle counting assembly measures the running length of the filter screen and transmits the length to the controller; and the controller is used for controlling the dehydration assembly, the air permeability detection assembly, the cleaning assembly, and the circle counting assembly to work. Through the closed-loop control of quantitative air permeability detection and hierarchical cleaning, the application realizes efficient and automatic cleaning of the filter screen of the belt filter press, has the advantages of water saving, environmental protection, adjustable cleaning intensity, avoidance of excessive washing, prolongation of the service life of the filter screen, and the like.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment technology, specifically a closed-loop cleaning system and method for belt filter press screens. Background Technology

[0002] Belt filter presses are commonly used solid-liquid separation equipment in industries such as municipal wastewater treatment, chemical processing, and food processing. They mainly consist of a feed hopper, a gravity dewatering zone, a wedge-shaped dewatering zone, and a filter belt pressing zone. Wet sludge is poured onto the filter screens and flows sequentially through the aforementioned zones as the screens move. During operation, the upper and lower filter screens gradually converge, clamping the wet sludge in the middle for compression and dewatering, ultimately forming a sludge cake, thus achieving solid-liquid separation. The filter screens, as the key filtration layer for retaining solid materials and as the carrier and encapsulating medium during the pressing process, directly affect the overall dewatering capacity and operational stability of the machine.

[0003] In the existing field of municipal wastewater treatment, in order to achieve better dewatering of sludge, flocculants such as PAM (polyacrylamide) or PAC (polyaluminum chloride) are often added during sludge pretreatment. However, as high molecular chemical agents, they have strong adhesiveness and are prone to gradually adhering to the filter screen surface during long-term use. While clogging the mesh structure of the filter screen itself, they also act as a bridge to further adhere sludge and aggravate mesh clogging.

[0004] Among existing solutions, most manufacturers choose to replace the filter screen after severe clogging. A few well-managed wastewater treatment plants will arrange for workers to perform high-pressure water jet cleaning on the filter screen at the end of the day or periodically. However, manual methods are slow and often affected by the workers' attitudes, resulting in unsatisfactory cleaning effects. Furthermore, workers rely entirely on their subjective experience to judge the degree of cleaning, making it difficult to establish a unified cleaning standard. Secondly, automatic cleaning systems with fixed intensity cannot adjust the cleaning intensity according to the degree of clogging, easily leading to insufficient or excessive cleaning.

[0005] Therefore, a closed-loop cleaning technology is needed that can stably obtain filter permeability, locate the detection areas before and after cleaning, and adjust the cleaning intensity according to the re-inspection results. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by providing a closed-loop cleaning system and method for belt filter press screens. This closed-loop cleaning system and method can solve the drawbacks of manual cleaning before shutdown on the same day, can automatically and quantitatively clean the endpoint, can avoid the influence of residual water on wet screen detection, and can avoid damage to the filter screen by fixed cleaning intensity.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A closed-loop cleaning system for a belt filter press screen includes a mounting frame for the filter screen to pass through and a controller. The mounting frame is equipped with a dewatering component, an air permeability detection component, at least one set of cleaning components, and a cycle counting component.

[0009] The dehydration component, located upstream of the air permeability detection component, is used to remove free water from the mesh openings of the filter screen.

[0010] The air permeability detection component is used to detect the air permeability characterization value before and after filter cleaning and transmit it to the controller;

[0011] The cleaning component is located downstream of the air permeability detection component. Based on the air permeability characterization value of the air permeability detection component, it performs cleaning operations on the filter screen by spraying water, brushing, and scraping and guiding the dirt.

[0012] The filter loop counting component measures the distance traveled by the filter and transmits this information to the controller to determine the number of cleaning loops required for the filter to be cleaned, in order to retest the air permeability of the filter or continue the cleaning operation.

[0013] The controller is used to receive signals from the air permeability detection component and the loop counting component and control the operation of the dehydration component, air permeability detection component, cleaning component and loop counting component.

[0014] The dehydration assembly includes an air knife with its outlet facing the filter screen. The air knife's outlet extends along the width of the filter screen, and the effective purging range of the air knife covers the width of the filter screen. The air knife is located on one side of the filter screen, and the controller can adjust the air knife's outlet pressure and / or outlet angle. The air knife blows away moisture from the filter screen surface and mesh before each test.

[0015] The air permeability detection component includes a detection head disposed on one side of the filter screen, an air source connected to the detection head, and a flow sensor and / or pressure sensor for detecting airflow parameters passing through the filter screen. The air source is connected to a controller to control the air supply flow rate or air supply pressure, so that the air source provides a preset air pressure or preset airflow to the detection head. The flow sensor and / or pressure sensor is connected to the controller to transmit flow signals and / or pressure signals. The other side of the filter screen does not have a support member that is pressed against the detection head, but serves as an open exhaust side.

[0016] The air permeability testing component includes a flexible sealing ring continuously arranged around the periphery of the testing port of the testing head, and a testing actuator that drives the testing head to move closer to or away from the filter screen. The testing actuator moves the testing head between a testing position and a retraction position. During testing, the testing actuator drives the testing head closer to the filter screen, so that the flexible sealing ring contacts one side surface of the filter screen and defines the testing area. The testing airflow provided by the air source passes through the filter screen and is discharged from the open exhaust side of the filter screen. After the test is completed, the testing actuator drives the testing head to retract from the filter screen.

[0017] The counting component is located downstream of the cleaning component or upstream of the dewatering component. The counting component includes a counting roller that rotates synchronously with the filter screen and a rotary encoder located at the end of the counting roller shaft. The counting roller is pressed against the filter screen and the rotary encoder is connected to the controller. The controller calculates the cumulative running length and cumulative running number of the filter screen based on the circumference of the counting roller, the cumulative number of revolutions or pulses of the rotary encoder, and the pre-stored total length of the filter screen, and determines the cleaning cycle number and the corresponding detection area before and after cleaning accordingly.

[0018] The controller is connected to the air source, detection actuator, and sensor in the air permeability detection component; the air knife in the dehydration component; the pressure regulating valve of the water spraying mechanism; the spacing adjustment mechanism and drive motor of the active brush roller component; and the rotary encoder in the count-ring component. After the area to be tested is purged with the air knife, the controller obtains the air permeability value before cleaning. After completing the set number of cleaning rings, it calculates the cumulative running length of the filter screen based on the circumference of the count-ring roller, the cumulative rotation of the rotary encoder, and the pre-stored total length of the filter screen. This allows the corresponding area to be tested before cleaning to be purged with the air knife again for re-inspection. If the re-inspection still fails to meet the standard, the controller resets the cleaning intensity based on the re-inspection results (changing at least one of the water spray pressure, brush roller contact amount, or number of cleaning rings). If the preset upper limit of the number of cleaning rings is still not met, an alarm signal is output.

[0019] The controller pre-stores the total length L0 of the filter screen and the circumference C of the counting roller. It calculates the cumulative running length L=nC of the filter screen based on the cumulative number of revolutions n or the equivalent number of pulses of the rotary encoder. When the cumulative running length L reaches an integer multiple of the total length L0 of the filter screen or is within its preset error range, it determines that the filter screen has run to the area to be inspected corresponding to the area before cleaning. After the area to be inspected is purged with an air knife, the area to be inspected is re-inspected.

[0020] The cleaning assembly includes a water spraying mechanism, an active brush roller assembly, and a guide scraper assembly arranged sequentially along the filter screen's running direction; or the cleaning assembly includes a water spraying mechanism, an active brush roller assembly, a water spraying mechanism, and a guide scraper assembly arranged sequentially along the filter screen's running direction, i.e., two sets of water spraying mechanisms within the same cleaning assembly are respectively arranged upstream and downstream of the active brush roller assembly; the water spraying mechanism, the active brush roller assembly, and the guide scraper assembly are respectively arranged in pairs on both sides of the filter screen; the water spraying mechanism washes both sides of the filter screen; the brush roller of the active brush roller assembly rotates actively against the filter screen's running direction, causing the bristles to enter the filter screen surface and mesh area and remove blockages; the guide scraper assembly scrapes the washed and brushed dirt off the filter screen surface and guides it to the dirt collection tanks on both sides.

[0021] The water spraying mechanism includes a water spray pipe extending along the width of the filter screen, adjustable nozzles spaced along the length of the water spray pipe, and a pressure regulating valve for controlling water pressure. The effective spray range of the water spray pipe covers the width of the filter screen, and the pressure regulating valve is connected to the controller via a circuit.

[0022] The active brush roller assembly includes a brush roller covered with bristles in the circumferential direction, a drive motor that drives the brush roller to rotate against the filter screen, and a spacing adjustment mechanism that adjusts the amount of contact between the brush roller and the filter screen. The bristles on the brush rollers located on both sides of the filter screen are staggered, and the tangential movement direction at the contact position between the brush roller and the filter screen is opposite to the running direction of the filter screen.

[0023] The active brush roller assembly further includes self-cleaning nozzles and / or cleaning combs for cleaning the brush roller bristles, the self-cleaning nozzles and / or cleaning combs being disposed on the side of the brush roller away from the filter screen.

[0024] The flow guide scraper assembly includes a scraper extending along the width of the filter screen, a replaceable elastic scraper blade, and a collection trough for collecting sewage and stripped dirt. The replaceable elastic scraper blade is located at the top of the scraper blade that contacts the filter screen. The scrapers located on both sides of the filter screen form an inverted V-shaped flow guide structure, and the bottom of the scraper blade is provided with a collection trough.

[0025] When multiple sets of cleaning components are provided, they are arranged sequentially downstream of the air permeability detection component. Meanwhile, the brush roller in the upstream cleaning component uses short bristles with high bending stiffness and a diameter smaller than the filter screen pore diameter, while the brush roller in the downstream cleaning component uses long bristles with bending stiffness lower than the short bristles.

[0026] The present invention also provides a closed-loop cleaning method using the above-mentioned closed-loop cleaning system, including the steps of pre-detection air knife dehydration, single-sided seal detection, deviation judgment, graded cleaning, cumulative running length and number of cycles calculation, corresponding re-inspection of the area to be detected, and over-limit alarm.

[0027] A closed-loop cleaning method using a belt filter press filter screen cleaning system comprises the following steps:

[0028] S1. Set the target air permeability, the total length of the filter screen to be cleaned, the dehydration air pressure of the dehydration component, the preset air pressure or preset airflow of the air permeability detection component, the upper limit of the number of cleaning cycles, and the cleaning intensity in the controller, and drive the filter screen to run, and proceed to step S2.

[0029] S2. Start the dehydration component, and the controller controls the air knife to blow away the free water in the mesh of the area to be tested of the filter screen. Then, turn off the dehydration component and proceed to step S3.

[0030] S3. When the area to be tested reaches the detection position of the air permeability detection component, reduce the running speed of the filter or make the filter stop briefly. The air permeability detection component presses the area to be tested and applies a preset air pressure or preset airflow. Based on the flow rate and / or pressure signal, the air permeability characterization value is obtained, and then proceed to step S4.

[0031] S4. Compare the air permeability characterization value obtained in step S3 with the target air permeability. If the air permeability characterization value is greater than or equal to the target air permeability, stop cleaning. If the air permeability characterization value is less than the target air permeability, proceed to step S5.

[0032] S5. The controller determines the cleaning intensity based on the air permeability characterization value obtained in step S3 and the air permeability deviation of the target air permeability. Based on the selected cleaning intensity, the controller sets the water spray pressure of the water spray mechanism in the cleaning component, the distance between the brush roller of the active brush roller component and the filter screen, and the running speed of the filter screen, and then proceeds to step S6.

[0033] S6. Start the water spray mechanism and active brush roller assembly in the cleaning component, and make the filter screen run at the set operating speed, then proceed to step S7.

[0034] S7. The water spraying mechanism on both sides of the filter screen sprays water to rinse simultaneously, and the brush rollers of the active brush roller assembly on both sides cooperate to wash. The guide scraper assembly in the cleaning component automatically scrapes and guides the dirt.

[0035] S8. The counting component records the cumulative number of revolutions of the counting roller or the cumulative number of pulses of the rotary encoder in real time and transmits it to the controller, then proceeds to step S9.

[0036] S9. The controller determines whether the filter has been cleaned completely. If not, it returns to step S7. If yes, the number of cleaning cycles is incremented by 1 and the process proceeds to step S10.

[0037] S10. Dehydration is performed using step S2, and air permeability is re-inspected using step S3. The air permeability characterization value obtained from the air permeability re-inspection is compared with the target air permeability using step S4. If the air permeability characterization value is ≥ the target air permeability, cleaning is stopped; if the air permeability characterization value is < the target air permeability, proceed to step S11.

[0038] S11. Determine the cleaning intensity using step S5, and proceed to step S12;

[0039] S12. Determine whether the number of cleaning cycles for the filter has reached the upper limit. Otherwise, return to step S7. If yes, trigger an alarm and require manual intervention.

[0040] The specific operation process of step S3 is as follows: When the area to be tested reaches the detection position of the air permeability detection component, the running speed of the filter screen is reduced or the filter screen is stopped briefly. The detection actuator drives the detection head to approach the filter screen, so that the flexible sealing ring contacts one side surface of the filter screen and defines the detection area. The controller controls the air source to supply air to the detection head in constant pressure mode and the flow sensor measures the air flow rate through the filter screen, or the controller controls the air source to supply air in constant flow mode and the pressure sensor measures the air pressure of the airflow through the filter screen. The detection airflow passes through the filter screen and is discharged from the open exhaust side of the filter screen. The measurement value obtained by the flow sensor or pressure sensor is transmitted to the controller. The controller uses the flow value under fixed pressure, or the pressure value under fixed flow rate, or the equivalent air permeability obtained by converting the measurement value as the measured air permeability characterization value. After the detection is completed, the detection actuator drives the detection head to retract from the filter screen.

[0041] The present invention has the following advantages over the prior art:

[0042] (1) The air permeability testing component has a testing head on only one side of the filter screen, and the other side of the filter screen is an open exhaust side. There is no need to set up a porous support plate or a relative pressing component, which simplifies the structure of the testing position and avoids the accumulation of dirt on the opposite support component or obstruction of the filter screen.

[0043] (2) The air knife is set upstream of the air permeability detection component so that the free water in the mesh surface and mesh holes is removed before each cleaning test and after cleaning retest. This can reduce the influence of water film on air permeability and improve the comparability of test results.

[0044] (3) The cumulative running length and cumulative running number of the filter screen can be directly calculated by using the circumference of the counting roller, the cumulative number of revolutions of the rotary encoder and the total length of the pre-stored filter screen. There is no need to set positioning marks and corresponding sensors on the filter screen. The cleaning number can be determined and the corresponding areas before and after cleaning can be re-inspected.

[0045] (4) The combination of double-sided water spraying, active brushing, inverted V-shaped scraping and graded brush bristles allows the blockages in the mesh, loose dirt on the mesh surface and cleaning wastewater to be peeled off, flushed and discharged in sequence, reducing secondary adhesion.

[0046] (5) When the adjustment limit is reached but the standard is still not met, an alarm will be automatically triggered, which makes it easier to identify stubborn blockages, filter damage or abnormal cleaning mechanism, and improve the standardization of maintenance. Attached Figure Description

[0047] Appendix Figure 1 This is a schematic diagram of the overall structure of the closed-loop cleaning system provided by the present invention;

[0048] Appendix Figure 2 A front view of the cleaning component provided by the present invention;

[0049] Appendix Figure 3 This is a cross-sectional schematic diagram of the air permeability testing component provided by the present invention;

[0050] Appendix Figure 4 This is a schematic diagram of the structure of the loop counting component provided by the present invention;

[0051] Appendix Figure 5 The control principle diagram of the closed-loop cleaning system provided by the present invention;

[0052] Appendix Figure 6 A flowchart of the closed-loop cleaning control method provided by the present invention.

[0053] Wherein: 1—mounting bracket; 2—filter screen; 3—air permeability detection component; 31—detection head; 32—flexible sealing ring; 33—detection actuator; 34—air source; 4—water spraying mechanism; 41—water spraying pipe; 42—spray head; 5—active brush roller assembly; 51—brush roller; 52—gap adjustment mechanism; 53—drive motor; 6—guide scraper assembly; 61—scraper; 62—elastic scraper; 63—sludge collection tank; 7—dehydration component; 71—air knife; 8—repeat counting component; 81—repeat counting roller; 82—rotary encoder; 9—controller. Detailed Implementation

[0054] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0055] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended meaning of inclusion and that other elements / components / etc. may exist in addition to the listed elements / components / etc.

[0056] like Figure 1-5As shown: A closed-loop cleaning system for a belt filter press screen includes a mounting frame 1 for the filter screen 2 to pass through and a controller 9. A dewatering component 7, an air permeability detection component 3, at least one set of cleaning components, and a ring counting component 8 are arranged on the mounting frame 1. The dewatering component 7 is located upstream of the air permeability detection component 3 and is used to remove free water from the mesh openings of the filter screen 2. The air permeability detection component 3 is used to detect the air permeability characteristics of the filter screen 2 before and after cleaning and transmit them to the controller 9. The cleaning component... The filter screen 2 is cleaned by spraying water, washing with brush rollers, and scraping and guiding dirt based on the air permeability characterization value of the air permeability detection component 3. The counting component 8 is used to measure the travel length of the filter screen 2 and transmit it to the controller 9 to determine the number of cleaning cycles of the filter screen 2, so as to retest the air permeability of the filter screen 2 or continue the cleaning operation. The controller 9 is used to receive the signals from the air permeability detection component 3 and the counting component 8 and control the operation of the dehydration component 7, the air permeability detection component 3, the cleaning component, and the counting component 8.

[0057] like Figure 1-2 As shown, the dehydration component 7 is located upstream of the air permeability detection component 3, and includes an air knife 71 disposed on one side of the filter screen 2. The air outlet of the air knife 71 extends along the width of the filter screen and sprays a high-speed airflow toward the filter screen surface and mesh area to blow away moisture from the screen surface and mesh before each air permeability test. The effective purging range of the air knife 71 covers the width of the filter screen 2, and its outlet pressure and / or outlet angle are adjustable. The controller 9 can start the air knife 71 before the area to be tested reaches the detection head 31, and can set the advance start time or corresponding purging length according to the filter screen running speed.

[0058] like Figure 1-3 As shown, the air permeability detection component 3 includes a detection head 31, a flexible sealing ring 32, a detection actuator 33, an air source 34, a flow sensor (not shown in the figure), and a pressure sensor (not shown in the figure). The detection head 31 is located on one side of the filter screen 2 and can form a circular, rectangular, or other closed detection port. The flexible sealing ring 32 is continuously arranged along the periphery of the detection port. The other side of the filter screen 2 opposite to the detection head 31 does not have a porous support plate or other relative pressing components, but serves as an open exhaust side for detecting airflow. In other embodiments, for filters with a large width, multiple air permeability detection heads 31 can be arranged along the width direction to obtain air permeability characterization values ​​for the edge, middle, and other sides respectively.

[0059] The detection actuator 33 can be a cylinder, an electric push rod, or a linear module. In the non-detection state, the detection head 31 maintains a gap with the filter screen 2 to prevent continuous friction between the filter screen 2 and the flexible sealing ring 32 during normal operation. During detection, the filter screen 2 operates at a preset low speed or stops briefly, and the detection actuator 33 pushes the detection head 31 closer to the filter screen 2, causing the flexible sealing ring 32 to contact one side of the filter screen 2 and define the detection area. The air source 34 can supply air to the detection head 31 in constant pressure mode, with the airflow through the filter screen 2 measured by a flow sensor, or it can supply air in constant flow mode, with the detection pressure measured by a pressure sensor. The detection airflow passes through the filter screen 2 and is discharged directly from the open exhaust side. The controller 9 can use the flow rate value under a fixed pressure, the pressure value under a fixed flow rate, or the equivalent permeability obtained through conversion as the permeability characterization value.

[0060] like Figure 1-2 As shown in Figure 4, the counting assembly 8 includes a counting roller 81 that presses against and rotates synchronously with the filter screen 2, and a rotary encoder 82 disposed at the shaft end of the counting roller 81. The rotary encoder 82 is connected to the controller 9. The controller 9 calculates the cumulative running length and cumulative running number of the filter screen 2 based on the circumference of the counting roller 81, the cumulative number of revolutions or pulses of the rotary encoder 82, and the pre-stored total length of the filter screen. The controller 9 pre-stores the total length L0 of the filter screen and the circumference C of the counting roller 81, and calculates the cumulative running length L=nC of the filter screen based on the cumulative number of revolutions n or equivalent pulses of the rotary encoder 82. When the cumulative running length of the filter screen reaches an integer multiple of the total length L0 of the filter screen 2 or is within its preset error range, the controller 9 determines that the area to be tested before cleaning will run to the air permeability detection assembly 3 again, thus eliminating the need to set positioning marks or identification sensors on the filter screen.

[0061] like Figure 5 As shown, the controller 9 can be a PLC, an industrial controller, or a control module with corresponding input / output interfaces. The controller 9 is connected to the air source 34, the detection actuator 33, and the sensor in the air permeability detection component 3; the air knife 71 in the dehydration component 7; the pressure regulating valve of the water spraying mechanism 4; the spacing adjustment mechanism 52 and the drive motor 53 of the active brush roller component 5; and the rotary encoder 82 in the count-ring component 8. After the area to be tested is blew by the air knife 71, the controller 9 obtains the air permeability characterization value before cleaning. After completing the set number of cleaning rings, it calculates the cumulative running length of the filter screen based on the circumference of the count-ring roller 82, the cumulative number of revolutions of the rotary encoder 82, and the total length of the pre-stored filter screen. This causes the corresponding area to be tested before cleaning to be blew by the air knife again for re-inspection. If the re-inspection still fails to meet the standard, the controller 9 resets the cleaning intensity based on the re-inspection results (changing at least one of the water spraying pressure, brush roller contact amount, and number of cleaning rings). If the preset upper limit of the number of cleaning rings is still not met, an alarm signal is output.

[0062] like Figure 1 and Figure 2 As shown, the cleaning assembly includes at least one set, which includes a water spraying mechanism 4, an active brush roller assembly 5, and a flow guide scraper assembly 6 arranged sequentially along the running direction of the filter screen 2. Alternatively, the cleaning assembly includes a water spraying mechanism 4, an active brush roller assembly 5, a water spraying mechanism 4, and a flow guide scraper assembly 6 arranged sequentially along the running direction of the filter screen 2. That is, two sets of water spraying mechanisms 4 in the same cleaning assembly are respectively arranged upstream and downstream of the active brush roller assembly 5. The water spraying mechanism 4, the active brush roller assembly 5, and the flow guide scraper assembly 6 are respectively arranged in pairs on both sides of the filter screen 2.

[0063] Furthermore, the water spraying mechanism 4 includes a water spray pipe 41 extending along the width of the filter screen 2, adjustable nozzles 42 spaced along the length of the water spray pipe 41, and a pressure regulating valve (not shown in the figure) for controlling water pressure. The effective spraying range of the water spray pipe 41 covers the width of the filter screen 2, and the pressure regulating valve is connected to the controller 9 via a circuit.

[0064] Furthermore, the active brush roller assembly 5 includes a brush roller 51 with bristles distributed circumferentially, a drive motor 53 that drives the brush roller 51 to rotate against the filter screen 2, and a spacing adjustment mechanism 52 that adjusts the contact amount between the brush roller 51 and the filter screen 2. The spacing adjustment mechanism 52 can be a cylinder, an electric push rod, or a linear module, making the contact amount between the brush roller 51 and the filter screen 2 adjustable. The two brush rollers 51 can be staggered along the running direction of the filter screen 2 to avoid excessive clamping pressure on the filter screen 2 on the same cross section. The drive motor 53 causes the brush roller 51 to rotate actively, and the tangential movement direction of the brush roller 51 at the contact position with the filter screen 2 is opposite to the running direction of the filter screen, so as to increase the relative movement speed between the bristles and the blockage. In addition, the active brush roller assembly 5 also includes a self-cleaning nozzle and / or cleaning comb for cleaning the bristles of the brush roller 51. The self-cleaning nozzle and / or cleaning comb are located on the side of the brush roller 51 away from the filter screen 2 and are used to remove the adhering sludge on the bristles.

[0065] In this embodiment, two sets of cleaning components are preferably arranged sequentially along the running direction of the filter screen 2. The brush roller 51 of the upstream cleaning component uses short bristles with high bending stiffness and the diameter of the short bristles is smaller than the pore diameter of the filter screen 2, so that the short bristles can enter the pore area and loosen and remove the compacted blockage inside the mesh. The brush roller 51 of the downstream cleaning component uses long bristles with lower bending stiffness than the short bristles, which is used to expand the contact range with the mesh surface and remove loose residue.

[0066] Furthermore, the guide scraper assembly 6 includes a scraper 61 extending along the width of the filter screen 2, a replaceable elastic scraper 62, and a collection trough 63 for collecting sewage and stripped dirt. The replaceable elastic scraper 62 is located at the top of the scraper 61 that contacts the filter screen 2. The scrapers 61 located on both sides of the filter screen 2 form an inverted V-shaped guide structure, and the bottom of the scraper 61 is provided with a collection trough 63. The elastic scraper 62 is in light contact with the filter screen 2, guiding the sewage and stripped dirt to the collection troughs 63 on both sides.

[0067] Free water: Free water or accumulated water that exists on the surface and inside the mesh of filter screen 2 and is not firmly bonded to the material of filter screen 2 or to clogging dirt; it can form a water film that interferes with air permeability detection and may also damage the instrument. It can be blown away by the high-speed airflow provided by air knife 71.

[0068] like Figure 6 As shown, a closed-loop cleaning method is implemented using a belt filter press filter screen closed-loop cleaning system. The steps of this closed-loop cleaning method are as follows:

[0069] S1. Set the target air permeability, the total length of the filter screen 2 to be cleaned, the dehydration air pressure of the dehydration component 7, the preset air pressure or preset airflow of the air permeability detection component 3, the upper limit of the number of cleaning cycles, and the cleaning intensity in the controller, and drive the filter screen 2 to run, and proceed to step S2.

[0070] S2. Start the dehydration component 7, and the controller 9 controls the air knife 71 to blow away the free water in the mesh of the area to be tested of the filter screen 2. Then, turn off the dehydration component 7 and proceed to step S3.

[0071] S3. When the area to be tested reaches the detection position of the air permeability detection component 3, the running speed of the filter 2 is reduced or the filter 2 is briefly stopped. The detection actuator 33 drives the detection head 31 to approach the filter 2, so that the flexible sealing ring 32 contacts one side surface of the filter 2 and defines the detection area. The controller 9 controls the air source 34 to supply air to the detection head 31 in constant pressure mode and the flow rate through the filter 2 is measured by the flow sensor, or the controller 9 controls the air source 34 to supply air in constant flow mode and the pressure sensor measures the air pressure through the filter 2. The detection airflow passes through the filter 2 through the detection head 31 and is discharged from the open exhaust side of the filter 2. The measurement value obtained by the flow sensor or pressure sensor is transmitted to the controller 9. The controller 9 uses the flow rate value under fixed pressure, or the pressure value under fixed flow, or the equivalent air permeability obtained by converting the measurement value as the measured air permeability characterization value. After the detection is completed, the detection actuator 33 drives the detection head 31 to retract from the filter 2. Proceed to step S4.

[0072] S4. Compare the air permeability characterization value obtained in step S3 with the target air permeability. If the air permeability characterization value is greater than or equal to the target air permeability, stop cleaning. If the air permeability characterization value is less than the target air permeability, proceed to step S5.

[0073] S5. The controller 9 determines the cleaning intensity based on the air permeability characterization value obtained in step S3 and the air permeability deviation of the target air permeability. Based on the selected cleaning intensity, it sets the water spraying pressure of the water spraying mechanism 4 in the cleaning component, the distance between the brush roller of the active brush roller assembly 5 and the filter screen 2, and the running speed of the filter screen 2, and then proceeds to step S6.

[0074] S6. Start the water spray mechanism 4 and the active brush roller assembly 5 in the cleaning assembly, and make the filter screen 2 run at the set operating speed, then proceed to step S7.

[0075] S7, the water spraying mechanism 4 on both sides of the filter screen 2 sprays water to rinse simultaneously, the brush rollers of the active brush roller assembly 5 on both sides cooperate to wash, and the guide scraper assembly in the cleaning component automatically scrapes and guides the dirt.

[0076] S8. The counting component 8 records the cumulative number of revolutions of the counting roller 81 or the cumulative number of pulses of the rotary encoder 82 in real time and transmits it to the controller 9, then proceeds to step S9.

[0077] S9. Controller 9 determines whether filter 2 has been cleaned completely. If not, return to step S7. If yes, increment the cleaning cycle count by 1 and proceed to step S10.

[0078] S10. Dehydration is performed using step S2, and air permeability is re-inspected using step S3. The air permeability characterization value obtained from the air permeability re-inspection is compared with the target air permeability using step S4. If the air permeability characterization value is ≥ the target air permeability, cleaning is stopped; if the air permeability characterization value is < the target air permeability, proceed to step S11.

[0079] S11. Determine the cleaning intensity using step S5, and proceed to step S12;

[0080] S12. Determine whether the number of cleaning cycles for filter 2 has reached the upper limit of the number of cleaning cycles. Otherwise, return to step S7. If yes, an alarm will be triggered and manual processing will be required.

[0081] Example

[0082] like Figure 1-6 As shown, the closed-loop cleaning system is installed in the return section of the filter screen 2 used in the belt filter press, preferably in the area where the filter screen 2 runs approximately vertically, to facilitate the discharge of cleaning wastewater under gravity. The mounting frame 1 is connected to the crossbeam or independent support of the belt filter press. Along the running direction of the filter screen 2, the dewatering component 7 is positioned upstream of the air permeability detection component 3, two sets of cleaning components are positioned downstream of the air permeability detection component 3, and the ring counting component 8 is positioned downstream of the cleaning components. Before entering the testing position, the filter screen 2 is first purged by the air knife 71; after testing and determining that cleaning is necessary, the filter screen 2 continues to enter the cleaning components. After the filter screen 2 completes cleaning and one cycle, it is re-tested by passing through the dewatering component 7 and the air permeability detection component 3.

[0083] The closed-loop cleaning method can be performed according to the following process. First, the controller 9 causes the area to be tested of the filter screen 2 to pass through the air knife 71, which blows away the free water on the screen surface and inside the mesh. When the area to be tested reaches the detection position of the air permeability detection component 3, the filter screen 2 is made to run at low speed or stop briefly. The detection head 31 approaches the filter screen 2, and the flexible sealing ring 32 contacts one side of the filter screen surface to obtain the air permeability characterization value before cleaning. The preset target value can be determined according to the detection value of a new filter screen or a filter screen that has been confirmed to be cleaned and qualified. Alternatively, multiple sets of target values ​​can be stored in advance for different filter screen specifications and filtration conditions. When the air permeability characterization value before cleaning reaches the preset target value, the cleaning component is not started. When it does not reach the preset target value, the detection head 31 retracts. The controller 9 selects the initial cleaning intensity level according to the air permeability deviation, starts double-sided water spraying, active brushing and scraping, and records the cumulative number of revolutions of the counting roller 81 or the cumulative number of pulses of the rotary encoder 82 through the counting component 8. The initial cleaning intensity level can be achieved using relatively low water spray pressure and relatively small brush roller contact to reduce unnecessary filter wear.

[0084] After completing the set number of cleaning cycles, controller 9 stops spraying water and brushing, and allows filter screen 2 to continue running. Controller 9 calculates the cumulative running length based on the circumference of the counting roller 81, the cumulative number of revolutions of the rotary encoder 82, and the pre-stored total length of the filter screen. When the area to be tested before cleaning approaches the air permeability detection component 3 again, the air knife 71 is first activated to blow away the moisture from the mesh surface and mesh openings of the area to be tested. Then, the detection head 31 is brought close to filter screen 2 again to obtain the re-inspection air permeability characterization value. When the re-inspection reaches the preset standard value, controller 9 stops cleaning and allows the belt filter press to return to normal operation. If the re-inspection fails to meet the standard, controller 9 increases at least one of the following: water spray pressure, brush roller contact amount, or number of cleaning cycles, and then performs cleaning and re-inspection again.

[0085] Table 1 shows examples of four levels of cleaning intensity, where the air permeability deviation is less than 200 L / M. 2 / S represents the normal deviation of the air permeability of filter 2.

[0086] Cleaning Intensity Level Classification Table

[0087]

[0088] The specific number and parameters of cleaning levels are determined by the material, mesh structure, type of blockage, and operating speed of filter 2. When any cleaning parameter reaches the preset upper limit or the number of repeated cleaning cycles reaches the preset value and the re-inspection still fails to meet the standard, controller 9 stops further enhanced cleaning and issues an alarm, prompting a check for irreversible blockage, structural damage, or malfunction of the cleaning mechanism in filter 2.

[0089] In this embodiment of the invention, the term "multiple" refers to two or more, unless otherwise explicitly defined. The terms "install," "connect," and "fix" should be interpreted broadly. For example, "connect" can mean a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention based on the specific circumstances.

[0090] In the description of the embodiments of the present invention, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0091] In the description of this specification, the terms "an embodiment," "a preferred embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0092] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention. Technologies not covered in this invention can be implemented using existing technologies.

Claims

1. A closed-loop cleaning system for belt filter press screens, characterized in that: The closed-loop cleaning system includes a mounting bracket (1) through which the filter (2) passes and a controller (9). The mounting bracket (1) is equipped with a dehydration assembly (7), an air permeability detection assembly (3), at least one set of cleaning components, and a loop counting assembly (8). The dehydration component (7) is arranged upstream of the air permeability detection component (3) and is used to remove free water from the mesh openings of the filter screen (2); The air permeability detection component (3) is used to detect the air permeability characterization value of the filter (2) before and after cleaning and transmit it to the controller (9). The cleaning component is arranged downstream of the air permeability detection component (3) and performs cleaning operations on the filter screen (2) by spraying water, brushing, and scraping and guiding the filter screen based on the air permeability characterization value of the air permeability detection component (3). The loop counting component (8) is used to measure the travel length of the filter (2) and transmit it to the controller (9) to determine the number of cleaning loops of the filter (2) so as to retest the air permeability of the filter (2) or continue the cleaning operation. The controller (9) is used to receive signals from the air permeability detection component (3) and the loop counting component (8) and control the operation of the dehydration component (7), the air permeability detection component (3), the cleaning component, and the loop counting component (8).

2. The closed-loop cleaning system for belt filter press screens according to claim 1, characterized in that: The dehydration assembly (7) includes an air knife (71) with its air outlet facing the filter screen (2). The air outlet of the air knife (71) extends along the width direction of the filter screen (2), and the effective purging range of the air knife (71) covers the width of the filter screen (2). The air knife (71) is located on one side of the filter screen (2), and the controller (9) can adjust the air outlet pressure and / or air outlet angle of the air knife (71).

3. The closed-loop cleaning system for belt filter press screens according to claim 1, characterized in that: The air permeability detection component (3) includes a detection head (31) disposed on one side of the filter (2), an air source (34) connected to the detection head (31), and a flow sensor and / or pressure sensor for detecting the airflow parameters passing through the filter (2). The air source (34) is connected to the controller (9) to control the air supply flow rate or air supply pressure of the air source (34). The flow sensor and / or pressure sensor is connected to the controller (9) to transmit flow signals and / or pressure signals.

4. The closed-loop cleaning system for belt filter press screens according to claim 3, characterized in that: The air permeability testing component (3) includes a flexible sealing ring (32) continuously arranged around the periphery of the testing port of the testing head (31) and a testing execution mechanism (33) that drives the testing head (31) to approach or move away from the filter screen (2). During testing, the testing execution mechanism (33) drives the testing head (31) to approach the filter screen (2), so that the flexible sealing ring (32) contacts one side surface of the filter screen (2) and defines the testing area, so that the air source (34) provides the testing airflow to the testing head (31), which passes through the filter screen (2) and is discharged from the open exhaust side of the filter screen (2). After the testing is completed, the testing execution mechanism (33) drives the testing head (31) to move away from the filter screen (2).

5. The closed-loop cleaning system for belt filter press screens according to claim 1, characterized in that: The counting component (8) is arranged downstream of the cleaning component or upstream of the dewatering component (7). The counting component (8) includes a counting roller (81) that rotates synchronously with the filter screen (2) and a rotary encoder (82) set at the shaft end of the counting roller (81). The counting roller (81) is pressed against the filter screen (2) and the rotary encoder (82) is connected to the controller (9). The controller (9) calculates the cumulative running length and cumulative running number of the filter screen (2) based on the circumference of the counting roller (81), the cumulative number of revolutions or pulses of the rotary encoder (82) and the pre-stored total length of the filter screen.

6. The closed-loop cleaning system for belt filter press screens according to claim 1, characterized in that: The cleaning assembly includes a water spraying mechanism (4), an active brush roller assembly (5), and a flow guide scraper assembly (6) arranged sequentially along the running direction of the filter screen (2), or the cleaning assembly includes a water spraying mechanism (4), an active brush roller assembly (5), a water spraying mechanism (4), and a flow guide scraper assembly (6) arranged sequentially along the running direction of the filter screen (2), that is, two sets of water spraying mechanisms (4) in the same cleaning assembly are respectively arranged upstream and downstream of the active brush roller assembly (5); the water spraying mechanism (4), the active brush roller assembly (5), and the flow guide scraper assembly (6) are respectively arranged in pairs on both sides of the filter screen (2).

7. The closed-loop cleaning system for belt filter press screens according to claim 6, characterized in that: The water spraying mechanism (4) includes a water spray pipe (41) extending along the width of the filter screen (2), adjustable nozzles (42) spaced along the length of the water spray pipe (41), and a pressure regulating valve for controlling water pressure. The effective spraying range of the water spray pipe (41) covers the width of the filter screen (2), and the pressure regulating valve is connected to the controller (9) via a line.

8. The closed-loop cleaning system for belt filter press screens according to claim 6, characterized in that: The active brush roller assembly (5) includes a brush roller (51) covered with bristles in the circumferential direction, a drive motor (53) that drives the brush roller (51) to rotate against the filter screen (2), and a spacing adjustment mechanism (52) that adjusts the amount of contact between the brush roller (51) and the filter screen (2). The bristles on the brush roller (51) located on both sides of the filter screen (2) are staggered, and the tangential movement direction at the contact position between the brush roller (51) and the filter screen (2) is opposite to the running direction of the filter screen (2).

9. The closed-loop cleaning system for belt filter press screens according to claim 8, characterized in that: The active brush roller assembly (5) further includes a self-cleaning nozzle and / or cleaning comb for cleaning the bristles of the brush roller (51), the self-cleaning nozzle and / or cleaning comb being disposed on the side of the brush roller (51) away from the filter screen (2).

10. The closed-loop cleaning system for belt filter press screens according to claim 6, characterized in that: The flow guide scraper assembly (6) includes a scraper (61) extending along the width of the filter screen (2), a replaceable elastic scraper (62), and a collection tank (63) for collecting sewage and stripped dirt. The replaceable elastic scraper (62) is located at the top of the scraper (61) that contacts the filter screen (2). The scrapers (61) on both sides of the filter screen (2) form an inverted V-shaped flow guide structure, and the bottom of the scraper (61) is provided with Sewage collection tank (63). When multiple sets of cleaning components are provided, they are arranged sequentially downstream of the air permeability detection component. Meanwhile, the brush roller in the upstream cleaning component uses short bristles with high bending stiffness and a diameter smaller than the filter screen pore diameter, while the brush roller in the downstream cleaning component uses long bristles with bending stiffness lower than the short bristles.

11. A closed-loop cleaning method implemented using a closed-loop cleaning system for belt filter press screens as described in any one of claims 1-10, characterized in that: The steps of this closed-loop cleaning method are as follows: S1. Set the target air permeability, the total length of the filter screen (2) to be cleaned, the dehydration air pressure of the dehydration component (7), the preset air pressure or preset airflow of the air permeability detection component (3), the upper limit of the number of cleaning cycles, and the cleaning intensity in the controller, and drive the filter screen (2) to run, and proceed to step S2. S2. Start the dehydration assembly (7), and the controller (9) controls the air knife (71) to blow away the free water in the mesh of the area to be tested in the filter screen (2). Then, turn off the dehydration assembly (7) and proceed to step S3. S3. When the area to be tested reaches the detection position of the air permeability detection component (3), reduce the running speed of the filter (2) or make the filter (2) stop briefly. The air permeability detection component (3) presses the area to be tested and applies a preset air pressure or preset airflow. Based on the flow rate and / or pressure signal, the air permeability characterization value is obtained, and the process proceeds to step S4. S4. Compare the air permeability characterization value obtained in step S3 with the target air permeability. If the air permeability characterization value is greater than or equal to the target air permeability, stop cleaning. If the air permeability characterization value is less than the target air permeability, proceed to step S5. S5. The controller (9) determines the cleaning intensity based on the permeability characterization value obtained in step S3 and the permeability deviation of the target permeability. Based on the selected cleaning intensity, it sets the water spraying pressure of the water spraying mechanism (4) in the cleaning component, the distance between the brush roller of the active brush roller assembly (5) and the filter screen (2), and the running speed of the filter screen (2), and then proceeds to step S6. S6. Start the water spray mechanism (4) and active brush roller assembly (5) in the cleaning assembly, and make the filter screen (2) run at the set operating speed, and proceed to step S7; S7, the water spraying mechanism (4) on both sides of the filter screen (2) sprays water to rinse simultaneously, and the brush rollers of the active brush roller assembly (5) on both sides cooperate to wash. The guide scraper assembly in the cleaning component automatically scrapes and guides the dirt. S8. The counting component (8) records the cumulative number of revolutions of the counting roller (81) or the cumulative number of pulses of the rotary encoder (82) in real time and transmits it to the controller (9), and proceeds to step S9. S9. The controller (9) determines whether the filter (2) has been cleaned completely. Otherwise, it returns to step S7. If yes, the number of cleaning cycles is increased by 1 and the process proceeds to step S10. S10. Dehydration is performed using step S2, and air permeability is re-inspected using step S3. The air permeability characterization value obtained from the air permeability re-inspection is compared with the target air permeability using step S4. If the air permeability characterization value is ≥ the target air permeability, cleaning is stopped; if the air permeability characterization value is < the target air permeability, proceed to step S11. S11. Determine the cleaning intensity using step S5, and proceed to step S12; S12. Determine whether the number of cleaning cycles of the filter (2) has reached the upper limit of the number of cleaning cycles. Otherwise, return to step S7. If yes, an alarm will be triggered and manual processing will be performed.

12. The closed-loop cleaning method according to claim 11, characterized in that: The specific operation process of step S3 is as follows: when the area to be tested reaches the detection position of the air permeability detection component (3), the running speed of the filter (2) is reduced or the filter (2) is stopped briefly, and the detection actuator (33) drives the detection head (31) to approach the filter (2), so that the flexible sealing ring (32) contacts one side surface of the filter (2) and defines the detection area; the controller (9) controls the air source (34) to supply air to the detection head (31) in constant pressure mode and the flow sensor measures the air flow through the filter (2), or the controller (9) controls the air source (34) to supply air to the detection head (31) in constant pressure mode and the flow sensor measures the air flow through the filter (2), or the controller (9) controls the air source (34) to supply air to the detection head (31) in constant pressure mode and the flow sensor measures the air flow through the filter (2), or the controller (9) controls the air source (34) to supply air to the detection head (31) in constant pressure mode and the flow sensor measures the air flow through the filter (2). In constant flow mode, air is supplied and the air pressure passing through the filter (2) is measured and detected by the pressure sensor; the detected airflow passes through the filter (2) through the detection head (31) and is discharged from the open exhaust side of the filter (2). The measured value obtained by the flow sensor or pressure sensor is transmitted to the controller (9). The controller (9) uses the flow value under fixed pressure, or the pressure value under fixed flow, or the equivalent permeability obtained by converting the measured value as the measured permeability characterization value; after the detection is completed, the detection actuator (33) drives the detection head (31) to retract from the filter (2).

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