Method and control system for cleaning filter cloth of a filter press.

Abstract

This invention provides a filter press filter cloth cleaning method and filter cloth cleaning control system that efficiently photographs the soiling status of each filter cloth with a camera and performs optimal filter cloth cleaning according to the soiling status of each filter cloth. [Solution] In a filter press in which a pair of filter cloths 5, 5 are suspended between parallel filter plates 4, 4, and the raw liquid is supplied to a filtration chamber 6 formed between the filter cloths 5, 5 for dewatering, and then the filter cloths 5 are raised and lowered while being wrapped around a lower return roll 20, multiple color standards are set in advance as indicators for determining the degree of soiling of the filter cloths 5 after cake discharge, and the amount of washing corresponding to each color standard is set, the surface of the filter cloths 5 after cake discharge is photographed with a camera 50, the color standard is determined from the acquired photographic data, and the amount of washing of the filter cloths 5 is controlled according to the color standard, thereby enabling optimal filter cloth washing according to the degree of soiling of the filter cloths.

Description

Technical Field

[0001] The present invention relates to a method for washing a pair of filter cloths suspended between filter plates, and particularly relates to a filter cloth washing method and a filter cloth washing control system for a filter press that control the washing amount according to the degree of soiling of the filter cloths.

Background Art

[0002] In a filter press, a pair of filter cloths is suspended from a plurality of filter plates arranged in parallel so as to be openable and closable, and a stock solution is press-fitted from a liquid supply plate fixed to the filter cloths into a filter chamber formed between the pair of filter cloths, so that solid-liquid separation is performed by the filter cloths. After the dewatering step is completed, the filter plates are opened to discharge the dewatered cake, and the filter cloths are washed.

[0003] Patent Document 1 discloses a filter press in which a pair of filter cloths is disposed between filter plates arranged in parallel so as to be openable and closable, the upper end of each filter cloth is connected to one end of a drive chain wound around a sprocket connected to a drive unit, the lower end of each filter cloth trained around a return roll is connected to the other end of the drive chain, and the filter cloths are configured to be movable up and down. As described above, a simultaneous plate opening type filter press in which all filter plates are opened at the same time, the filter cloths of all filter chambers travel up and down simultaneously to peel off the dewatered cake held between the pair of filter cloths from the filter cloths, and the filter cloths are washed in the vicinity of the return roll is known.

[0004] Patent Document 2 discloses a filter press that controls the driving of a cake peeling device by photographing the filter cloth of the filter press with a camera and detecting the presence or absence of dewatered cake from the shade of the filter cloth with an image processing device.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of Invention

[0006] The filter press described in Patent Document 1 is a mechanism that sprays cleaning solution onto the filter cloth from a fixed cleaning nozzle. Because the spray is performed while the filter cloth is moving, it is possible to clean the entire surface of the filter cloth. However, since the filter cloth only moves a certain number of times during the initial setup, depending on the degree of soiling of the filter cloth, it may result in insufficient cleaning or over-cleaning. Furthermore, because the filter cloths installed in all filtration chambers are cleaned uniformly, flexible cleaning according to the degree of soiling of each filter cloth is not possible.

[0007] The filter press described in Patent Document 2 is a sequential-opening type in which the filtration chambers are opened one chamber at a time, and a fixed filter cloth is used between the filter plates. A support arm equipped with a camera is moved between the sequentially opening filter plates to photograph the filter cloth and dewatered cake inside the filtration chamber from the side, and the video signal is sent to an image processing device. Because the filter cloth is fixed, it is necessary to image from directly beside the opened filtration chamber.

[0008] Applying the imaging means described in Patent Document 2 to a filter press with simultaneous opening plates would increase downtime because the support arm equipped with the camera would need to be moved for each chamber. While installing a camera on the side of each filtration chamber would reduce the increase in downtime, it would incur enormous costs and would not be practical. Furthermore, because the opening distance for each chamber when opening the filtration chamber plates is smaller compared to a sequential opening type, it is difficult to photograph the entire filter cloth from only one side of the filter plate.

[0009] The present invention provides a filter press filter cloth cleaning method and filter cloth cleaning control system that efficiently photographs the soiling state of each filter cloth with a camera when raising and lowering each filter cloth, and performs optimal filter cloth cleaning according to the soiling state of the filter cloth. [Means for solving the problem]

[0010] The present invention relates to a filter press in which a pair of filter cloths are suspended between parallel filter plates, a raw liquid is supplied to a filtration chamber formed between the filter cloths for dewatering, and the filter cloths are raised and lowered while being wrapped around a lower return roll. In this invention, multiple color standards are set in advance as indicators for determining the degree of soiling of the filter cloths after cake discharge, and the amount of washing is set according to each color standard. The surface of the filter cloths after cake discharge is photographed with a camera, the color standard is determined from the acquired photographic data, and the amount of washing of the filter cloths is controlled according to the color standard, thereby enabling accurate determination of the degree of soiling of the filter cloths and enabling optimal washing according to the degree of soiling of the filter cloths.

[0011] The washing volume can be set from at least one of the following: the number of times the filter cloth is raised and lowered, the range of the filter cloth's movement, the speed of the filter cloth's movement, the opening of the washing pipe, and the rotation speed of the washing water pump, thereby enabling appropriate washing control.

[0012] By dividing the filter cloth surface into two or more sections and controlling the amount of cleaning according to the degree of soiling in each section, cleaning can be performed according to the soiling distribution of the filter cloth.

[0013] By installing valves in branch pipes that branch off from the aforementioned cleaning pipe to each filtration chamber and spray cleaning water onto the corresponding filter cloth, the parallel filtration chambers can be divided into two or more, and the amount of cleaning can be adjusted by adjusting the opening of the valve for each divided filter cloth, thereby switching the filter cloth cleaning control for each corresponding filtration chamber.

[0014] A color standard is set as an indicator for determining the cleanliness of the filter cloth after cleaning. The surface of the filter cloth after cleaning is photographed with a camera, and the color standard after cleaning is determined from the acquired photographic data. If the photographic data falls outside the range of the color standard after cleaning, control is performed to change at least one of the color standards after cake discharge, which are set in multiple stages, or the cleaning amount set according to the color standard. This allows the optimal cleaning control to be updated according to the degree of soiling of the filter cloth after cleaning.

[0015] This control system for a filter press involves suspending a pair of filter cloths between parallel filter plates, supplying a raw liquid to a filtration chamber formed between the filter cloths for dewatering, and then raising and lowering the filter cloths while winding them onto a lower return roll. The system includes a model constructed by machine learning using training data that includes photographic data of the filter cloth surface after dewatering cake discharge, washing amount data during filter cloth washing, and photographic data of the filter cloth surface after washing. The control system is configured to input photographic data of the filter cloth surface after dewatering cake discharge into the model, calculate the optimal washing amount data during filter cloth washing according to the model, further input photographic data of the filter cloth surface after washing into the model, evaluate the appropriateness of the washing amount data, and update the model based on the evaluation results, thereby always being able to derive the optimal washing amount. [Effects of the Invention]

[0016] This invention allows for appropriate control of the amount of water used to wash the filter cloth and the number of washes, resulting in water savings. Furthermore, efficient filter cloth washing extends the lifespan of the filter cloth and reduces the frequency of replacement. This contributes to reduced operating costs and a lighter environmental impact. It eliminates the need to install detection devices on each filter cloth, allowing for space-saving and cost-effective monitoring of the filter cloth's condition, while also improving and simplifying maintenance. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic side view of a filter press according to the first embodiment of the present invention. [Figure 2] This is also a front view of the filter plate. [Figure 3] This is also a perspective view of the filter cloth. [Figure 4] This is also a plan view of the main components of the filter cloth drive device. [Figure 5] Similarly, this is a schematic diagram of the filter cloth drive mechanism. [Figure 6] This is a longitudinal cross-section of the filtration chamber. [Figure 7]FIG. 2 is a schematic side view of a filter press according to the second embodiment of the present invention. [Figure 8] Similarly, it is a schematic side view of a filter press according to the third embodiment. [Figure 9] This is a filter cloth image created by the control device according to the present invention. [Figure 10] This is a flowchart of the operation method of the filter press according to the present invention. [Figure 11] This is a diagram for explaining the flow of a filter press control system according to another embodiment of the present invention. MODE FOR CARRYING OUT THE INVENTION

[0018] FIG. 1 is a schematic side view of a filter press according to the first embodiment of the present invention. The filter press is configured such that a plurality of filter plates 4 are slidably mounted on guide rails 3 bridged between a front frame 1 and a rear frame 2 so as to be movable in the front-rear direction, and a filter cloth 5 is suspended between these filter plates 4.

[0019] Above the row of the plurality of filter plates 4, a slide shaft 7 is provided along the row of filter plates 4. On the slide shaft 7, a bevel gear slide 8 for suspending the filter cloth 5 is fitted so as to be slidable in the axial direction. A clamping cylinder 9 is supported on the rear frame 2. By extending the clamping cylinder 9 to press the row of filter plates 4 toward the front frame 1, the filter plates 4 are closed. When the stock solution is supplied into the filter chamber 6 between the closed filter plates 4, 4, the filtrate passes through the filter cloth 5 and is discharged to the outside. The solid matter captured by the filter cloth 5 is dewatered while forming a cake layer.

[0020] After the dewatering is completed, the clamping cylinder 9 is retracted to open the filter plates 4. The respective filter plates 4 can be opened all at once at a predetermined interval determined by a connection link (not shown) that connects adjacent filter plates 4 to each other. Then, the drive device 12 for the filter cloth 5 is operated to lower the filter cloth 5 and discharge the dewatered cake. The filter plates 4 arranged in parallel may be a filter plates and diaphragm filter plates arranged alternately in parallel.

[0021] The cleaning pipe 21 is connected at one end to the cleaning tank 53 and branches at the other end to the bottom of each filtration chamber 6. Multiple cleaning nozzles 24 are opened in each branched pipe 33, and each is configured to spray cleaning water onto the surface of the corresponding filter cloth 5. When the valve V1 located in the middle of the cleaning pipe 21 is opened and the cleaning water pump 52 is driven, the cleaning water stored in the cleaning tank 53 is drawn up and sprayed from the cleaning pipe 21 through each branched pipe 33 onto the filter cloth 5 after the dewatered cake has been discharged via the cleaning nozzles 24. Immediately after the dewatered cake has been discharged, there is a risk that insufficiently detached dewatered cake may adhere to the surface of the filter cloth 5 and cause clogging of the filter cloth 5, so the dewatered cake adhering to the filter cloth 5 is removed by cleaning the filter cloth 5.

[0022] A camera 50 is installed near the bottom of the rear frame 2, and a single camera 50 is configured to photograph the underside of all filter plates 4 from below when they are open. Since the underside of the filter plates 4 is covered with a filter cloth 5, the entire surface of the filter cloth 5 can be photographed by operating the drive unit 12 to move the filter cloth 5 and photographing the underside of the filter cloth 5 at predetermined intervals with the camera 50. By photographing the surface of the filter cloth 5 immediately after the dewatered cake is discharged, it is possible to identify the filter cloth 5 that has dirt attached to it from among the filter cloths 5 suspended in each filtration chamber 6, and to identify the areas on the surface of the filter cloth 5 where dirt has attached.

[0023] The image data acquired by the imaging device 50 is transmitted to the control device 51. The control device 51 analyzes the image data and determines the presence and degree of dirt on the surface of the filter cloth 5 based on image information such as brightness, hue, and saturation. Depending on the determination result, the control device 51 controls the amount of cleaning during the cleaning of the filter cloth 5. In Figure 1, the control device 51 is connected to the drive device 12 of the filter cloth 5 and is configured to control the amount of cleaning by adjusting the number of times the filter cloth 5 is raised and lowered, the range of raising and lowering, and the speed of raising and lowering during cleaning, but the destination to which the control device 51 is connected is not limited. For example, by connecting it to the cleaning water pump 52, the amount of cleaning can be controlled by adjusting the discharge amount of the cleaning water pump 52.

[0024] Although the imaging device 50 shown in Figure 1 is located near the bottom of the rear frame 2, it may also be located on the front frame 1 side. Alternatively, one imaging device 50 may be installed on each side of the front frame 1 and rear frame 2. The imaging device 50 on the front frame 1 side may be used to photograph half of the filter cloth 5 on the front side, and the imaging device 50 on the rear frame 2 side may be used to photograph half of the filter cloth 5 on the rear side. The imaging range may be set so that all of the filter cloth 5 is photographed by the two imaging devices 50. Furthermore, if the imaging ranges of the two imaging devices 50 located on the front frame 1 side and the rear frame 2 side are set so that all of the filter cloth 5 can be photographed, the accuracy of the judgment can be improved by comparing the imaging data from the two imaging devices 50.

[0025] Furthermore, although the imaging device 50 shown in Figure 1 is installed independently near the rear frame 2, the installation method is not limited to fixing it to the filter press body, for example.

[0026] Figure 2 is a front view of the filter plate according to the present invention. The tensioning device 13 for the filter cloth 5 consists of an upper suspension device 13a disposed on the upper part of the filter plate 4 and a lower suspension device 13b disposed on the lower part. The upper suspension device 13a comprises a pair of upper brackets 14, 15 erected on both shoulders of the filter plate 4, a filter cloth drive shaft 16 supported by these, a slide gear housing 17 connected to one end of the filter cloth drive shaft 16 and supported on one of the upper brackets 14, and a pair of sprockets 18 fitted to both ends of the filter cloth drive shaft 16. On the other hand, the lower suspension device 13b comprises a pair of lower brackets 19, 19 hanging down from the lower ends on both sides of the filter plate 4, and a branch pipe 33 having two return rolls 20 and a washing nozzle 24 supported by these.

[0027] Figure 3 is a perspective view of the filter cloth according to the present invention. A pair of rectangular filter cloths 5, 5 have a cylindrical upper edge 22a formed by joining their upper ends together, folding them over, and sewing them, and a pair of cylindrical lower edges 23a formed by folding over and sewing their respective lower ends. Upper filter cloth cores 22 and lower filter cloth cores 23, which are longer than the width of the filter cloth 5, are inserted through and secured to the upper edge 22a and lower edge 23a, respectively. Drive chains 27, each having a tightener bolt at its end, are connected to both ends of the upper filter cloth core 22. A liquid supply plate 25 for the raw liquid is sandwiched in the upper center of the pair of filter cloths 5. The liquid supply plate 25 is provided with a raw liquid passage 26 that penetrates from the front to the rear, and a liquid supply passage 26a that penetrates from the lower inner circumferential surface of the raw liquid passage 26 to the lower end of the liquid supply plate 25.

[0028] Figure 4 is a plan view of the main part of the filter cloth drive device according to the present invention. A drive unit 12 capable of forward and reverse rotation is mounted on the rear frame 2. The drive shafts 39, 39 of the drive unit 12, which extend to the left and right, are supported by bearing units 40, 40 and connected to conversion gears 32, 32 arranged on the frames 41, 41 at both ends of the rear frame 2. Slide shafts 7, 7, arranged along the shoulders of the parallel filter plates 4, are connected to the conversion gears 32 of the rear frame 2, and the other end is pivotally supported by a bearing unit 43 arranged on the frame 42 of the front frame 1. The drive unit 12 is driven to rotate the slide shafts 7 in forward and reverse directions.

[0029] Figure 5 is a schematic diagram of the filter cloth drive mechanism. The bevel gear slide 8, pivotally supported by the slide gear housing 17, meshes with an input bevel gear 31 fitted to the end of the filter cloth drive shaft 16. This meshing state is always maintained during the opening and closing operation of the filter plates 4. A slide shaft 7 with a polygonal cross-section, extending in the front-rear direction of the filter press, is fitted to the bevel gear slide 8 so as to be immobile but axially slidable. The slide gear housing 17 and the upper brackets 14 and 15 supporting it are alternately arranged on the left and right shoulders of the parallel filter plates 4 so as not to interfere with each other between adjacent filter plates 4 when the plates are closed. At this time, the sprockets 18 of the filter cloth drive shaft 16 of each filter plate 4 are aligned on the same straight line.

[0030] As shown in Figure 1, a pair of slide shafts 7, slidably supported on the upper bracket 14 of the filter plate 4 via a slide gear housing 17, extend parallel to each other in the front-to-back direction of the filter press on both the left and right sides above the filter plate 4. The front and rear ends of each slide shaft 7 are rotatably supported on the front frame 1 and rear frame 2, respectively. The front ends of the pair of slide shafts 7 are linked via conversion gears 32 to a reversible drive device 12 installed on the rear frame 2. By driving this drive device 12, the left and right slide shafts 7 can be rotated by a predetermined amount, causing the filter cloth 5 between the parallel filter plates 4 to be raised and lowered simultaneously.

[0031] Figure 6 is a longitudinal cross-sectional view of the filtration chamber according to the present invention. A sprocket 18 connected to a drive source is located above the filter plate 4, and a pair of return rolls 20, 20 are located below the filter plate 4. An upper filter cloth core 22, inserted through the upper ends of a pair of filter cloths 5, 5, is connected to one end of a drive chain 27 that is wrapped around the sprocket 18. The lower ends of the filter cloths 5, 5 are wrapped around the pair of return rolls 20, 20 in a direction away from each other, and the lower filter cloth core 23 of the lower ends of the filter cloths 5, 5, which are suspended from the front and rear filtration beds 4a of the filter plate 4, are locked to a locking device 28. The locking device 28 is connected to the other end of the drive chain 27 via an adjustment device 29. By rotating the sprocket 18 connected to the drive device 12, the filter cloth 5 suspended between the open filter plates 4, 4 can be raised and lowered.

[0032] When the parallel filter plates 4 are closed, the liquid supply plate 25 suspended from the filter cloth 5 is sandwiched between the front and rear filter plates 4, 4, forming a filtration chamber 6 between the pair of filter cloths 5, 5 suspended from the filtration bed 4a of the filter plates 4. The liquid supply passage 26 of the liquid supply plate 25 is connected to the liquid supply passage 30 formed in the upper center of the filter plate 4, and the liquid is injected under pressure into the filtration chamber 6 between the filter cloths 5, 5 to perform solid-liquid separation. After dewatering, the parallel filter plates 4 are opened and the pair of filter cloths 5, 5 are moved downward. As the filter cloths bend and move away from each other by the pair of return rolls 20, 20 below the filter plates 4, 4, the cake adhering to the filter cloths 5 is peeled off.

[0033] After the dewatered cake is discharged, the filter cloth 5 is moved along the surface of the filter cloth 5 by spraying cleaning water introduced into the cleaning pipe 21 onto the surface of the filter cloth 5. One end of the cleaning pipe 21 is connected to the cleaning water pump 52, and the other end is branched at each filtration chamber 6 and connected to branch pipes 33. The branch pipes 33 extend along the lower part of the return roll 20 and are equipped with multiple cleaning nozzles 24 to ensure that the filter cloth 5 is cleaned thoroughly in the width direction. The cleaning nozzles 24 open to allow cleaning water to be sprayed onto the surface of the filter cloth 5 as it moves along the return rolls 20, 20. When the cleaning water pump 52 is started, cleaning water stored in the cleaning tank 53 is introduced into the cleaning pipe 21, and the cleaning water is sprayed from the cleaning nozzles 24 opened in each branch pipe 33 to clean the filter cloth 5. By spraying cleaning water while the filter cloth 5 moves up and down, the entire surface of the filter cloth 5 can be cleaned.

[0034] Figures 7 and 8 are schematic side views of a filter press according to another embodiment of the present invention. As shown in Figure 7, the washing pipe 21 may be configured to allow adjustment of the amount of washing applied to each filter cloth 5 by interposing a valve at each branch pipe 33 where it branches off for each filtration chamber 6. Alternatively, as shown in Figure 8, by consolidating the branch pipes 33 for each predetermined number of filtration chambers 6 and providing a valve, the parallel filter cloths 5 can be divided into multiple blocks for washing.

[0035] In this invention, after the dewatered cake is discharged and before the filter cloth is washed, the surface of the filter cloth 5 is photographed using the imaging device 50 to capture the degree of soiling of the filter cloth 5. By controlling the amount of water used to wash the filter cloth 5 using the control device 51 according to the degree of soiling of the filter cloth 5 captured in the photograph, the filter cloth 5 can be washed without excess or deficiency, and the amount of water used for washing and the washing time can be shortened.

[0036] The imaging range of the imaging device 50 is the surface of the filter cloth 5 located below the filter plate 4 shown in Figure 6, and can be, for example, the range from the return roll 20 to the vicinity of the lower filter cloth core metal 23. At this time, the imaging angle and imaging range will vary depending on the placement of the imaging device 50, but by raising and lowering the filter cloth 5 in the vertical direction and imaging at predetermined intervals, the entire surface of the filter cloth 5 can be imaged without problems regardless of the imaging surface of the filter cloth 5. Note that the imaging interval of the filter cloth 5 by the imaging device 50 may be set not only by predetermined time, but also, for example, by a predetermined amount of rotation of the slide shaft 7. In addition, light may be irradiated onto the imaging surface as needed.

[0037] Figure 9 shows a filter cloth image created by the control device according to the present invention. After the dewatering is complete, the filter plate 4 is opened and the slide shaft 7 is rotated to lower the filter cloth 5 all at once, discharging the dewatered cake from the filter cloth 5. At this time, the camera 50 starts taking pictures simultaneously with the start of the descent of the filter cloth 5, and takes multiple pictures at predetermined intervals until the descent of the cloth 5 is complete. This photographic data is transmitted to the control device 51, which combines the consecutive photographic data to create a filter cloth image 53 as shown in Figure 9.

[0038] The filter cloth image 53 displays the degree of soiling on the surface of the filter cloth 5 as captured by the imaging device 50. The soiling status is displayed in a way that allows for the determination of not only where the soiling is attached to the filter cloth 5, but also the degree of soiling. In the filter cloth image 53 shown in Figure 9, lighter colored areas in the upper part of the filter cloth image 53 indicate areas with less soiling, while darker colored areas in the lower part of the filter cloth image 53 indicate areas with more soiling, thus showing the difference in the degree of soiling through the shade of color.

[0039] The degree of contamination can be determined by analyzing the image information such as brightness, hue, and saturation of the captured data acquired by the imaging device 50. Since the contamination adhering to the filter cloth 5 takes on various colors depending on the type and properties of the raw liquid to be dewatered, the optimal values ​​for easily identifying the contamination can be selected from the image information such as brightness, hue, and saturation contained in the captured data, according to the season, site, operating conditions, etc.

[0040] The filter cloth image 53 created by the control device 51 may be a grayscale image that expresses the degree of soiling using shades of black and white, as shown in Figure 9, or a color image may be created. In addition, one or more filter cloths 5 may be analyzed when creating one filter cloth image 53, and this can be selected according to the number of filter cloths 5 to be controlled at once in the subsequent filter cloth 5 washing control. In this embodiment, a filter cloth image 53 is created by combining multiple consecutive captured data, but the system may also be configured to determine the soiling state of the filter cloth 5 based on the captured data without creating a filter cloth image 53.

[0041] In the filter cloth image 53 shown in Figure 9, for example, when the surface of the filter cloth 5 is divided into three sections vertically—upper, middle, and lower—the upper section is less soiled, the middle section is clean, and the lower section is heavily soiled. Based on these determination results, the control device 51 controls the amount of cleaning in the vertical direction of the filter cloth 5. As for how to set the amount of cleaning, for example, the amount of cleaning can be varied from the top to the bottom of the filter cloth 5 according to the degree of soiling, such as reducing the amount of cleaning in the upper section where the degree of soiling is less, not cleaning in the clean middle section, and increasing the amount of cleaning in the lower section where the degree of soiling is greater. Alternatively, the amount of cleaning water can be set to a level corresponding to the heavily soiled lower section and supplied from the top to the bottom of the filter cloth 5. Each cleaning amount can be set in multiple stages according to the degree of soiling. In addition, the surface of the filter cloth 5 may be divided horizontally, and the amount of cleaning may be controlled for each divided section.

[0042] The amount of washing can be adjusted by changing at least one of the following methods: changing the number of times the filter cloth is raised and lowered, the range of raising and lowering, or the speed of raising and lowering; adjusting the opening degree of the washing pipe 21; or adjusting the rotation speed of the washing water pump 52.

[0043] Further, in a filter press having a washing pipe 21 that branches to a branch pipe 33 via a valve for each filter chamber 6 or for every plurality of filter chambers 6 as shown in Figures 7 and 8, the filter cloths 5 arranged in parallel along the row of filter plates 4 can be washed by being divided one by one or every plurality of pieces through operation of each valve. Therefore, by creating a filter cloth image 53 showing the dirt state of the filter cloth 5 for each single filter cloth or for every plurality of filter cloths with the control device 51, it is also possible to control the washing amount according to the dirt state of each filter cloth 5.

[0044] As a method for setting the washing amount according to the dirt state, a plurality of levels of color references serving as discrimination indexes for the dirt state of the filter cloth 5 after cake discharge are set in advance through experiments, tests and the like, and a washing amount corresponding to each color reference is set respectively, so that the color displayed in the imaging data or the filter cloth image 53 acquired after cake discharge is compared with the color references, and the washing amount can be controlled according to the corresponding color reference.

[0045] In addition, a color reference serving as a discrimination index for the dirt state of the filter cloth 5 after washing the filter cloth 5 may be additionally set. By photographing the filter cloth 5 again after washing the filter cloth 5 and feeding the photographed data back to the control device 51, the color of the photographed data is compared with the color reference after washing the filter cloth 5, and when the photographed data falls outside the range of the reference value, it is determined that the washing amount control for the filter cloth 5 is not optimal, and control can be performed to change at least one of the multi-level set color references after cake discharge or the washing amount set according to the color references. In addition, by setting the color references after washing the filter cloth 5 to a plurality of levels, the increase / decrease range of the color references after cake discharge and the washing amount changed by feedback control can be set to a plurality of levels according to the dirt state.

Examples

[0046] Figure 10 is a flowchart of the operation method of the filter press according to the present invention. <A. Initial Setting> In advance, the optimal cleaning amount corresponding to various contamination states of the filter cloth 5 is set through experiments, tests, or the like. Specifically, this is performed by setting color references serving as judgment indicators for the contamination state of the filter cloth 5 after cake discharge in a plurality of stages, and setting the cleaning amount corresponding to each color reference respectively. The color references are set based on image information such as lightness, hue, and saturation. The cleaning amount is set from at least one of the number of elevating / lowering times of the filter cloth, the elevating / lowering range of the filter cloth, the elevating / lowering speed of the filter cloth, the opening degree of the cleaning pipe 21, and the rotation speed of the cleaning water pump 52.

[0047] <B. Dewatering> The tightening cylinder 9 is extended to close the row of filter plates 4, and the raw liquid is press-fitted into the filter chambers 6 formed between the closed filter plates 4, 4. The filtrate passes through the filter cloth 5 and is discharged to the outside, and the solid matter captured by the filter cloth 5 is dewatered while forming a cake layer.

[0048] <C. Cake Discharge> After dewatering is completed, the tightening cylinder 9 is retracted to open the row of filter plates 4, so that the cake in the filter chambers 6 falls downward. The cake remaining in the filter chambers 6 without being peeled off from the filter cloth 5 is discharged by operating the drive device 12 to cause the filter cloth 5 to travel downward.

[0049] <D. Filter Cloth Imaging> At the same time as the drive device 12 is started to cause the filter cloth 5 to travel downward during cake discharge, imaging of the filter cloth 5 is started by the imaging device 50 provided below the rear frame 2. The lower surfaces of the filter cloths 5 suspended in all the filter chambers 6 are imaged all at once by one imaging device 50. Imaging is performed at predetermined time intervals while the downward travel of the filter cloth 5 is continued, and the imaging ends at the same time as the travel of the filter cloth 5 stops. The imaging of the filter cloth 5 does not have to be performed simultaneously with cake discharge, and may be performed while raising the filter cloth 5 after the downward movement of the filter cloth 5 and cake discharge are completed.

[0050] <E. Contamination State Determination> The imaging data acquired by the imaging device 50 is transmitted to the control device 51. The control device 51 analyzes the imaging data to create a filter cloth image 53 that reflects the contamination state of the filter cloth 5. From the filter cloth image 53, the contaminated locations on the filter cloth 5 and the degree of contamination can be distinguished by differences in color and shading displayed on the image. The filter cloth image 53 is compared with the color reference set during initial setup, and the color reference corresponding to the contamination state of the filter cloth 5 is determined.

[0051] <F. Filter Cloth Cleaning> After the color reference corresponding to the contamination state of the filter cloth 5 is determined from the filter cloth image 53, the control device 51 transmits a command to perform cleaning control of the filter cloth 5 based on the cleaning amount set corresponding to each color reference. Since the filter cloth 5 can be cleaned with an appropriate cleaning amount according to various contaminants adhering to the filter cloth 5, the amount of cleaning water and cleaning time can be reduced.

[0052] <B. Dewatering> When the cleaning of the filter cloth 5 is completed, the tightening cylinder 9 is extended again to close the row of filter plates 4, and the stock solution is supplied to the filter chamber 6 to perform dewatering.

[0053] Note that if a location where the contamination state does not improve at all despite repeated multiple cleaning cycles is found, it may be configured to determine that the contamination is fixed on the filter cloth 5 and cannot be cleaned, or that there is a filter cloth abnormality such as breakage, issue an alarm to the operator, or skip subsequent filter cloth cleaning operations.

[0054] Additionally, additional images of filter cloth 5 may be taken immediately after the filter cloth has been washed. By setting a color standard as an indicator for determining the cleanliness of filter cloth 5 after washing, it is possible to compare the post-wash image data with the color standard to determine whether the dirt on filter cloth 5 has been sufficiently washed. This makes it possible to change the washing amount by increasing it by one level in subsequent filter cloth washes if the washing amount was not optimal, or to use feedback control to appropriately change the initial setting value according to the dirt status after filter cloth washing. Alternatively, instead of setting a color standard for filter cloth 5 after washing, the system may be configured to determine the appropriateness of the washing amount by comparing the image data of filter cloth 5 after washing with the image data of filter cloth 5 immediately after cake discharge.

[0055] As another embodiment of the present invention, by using machine learning techniques on the image data of the filter cloth 5 surface after dewatering cake discharge, the optimal amount of cleaning can be calculated each time according to the degree of soiling of the filter cloth 5. In addition, by using the image data of the filter cloth 5 surface after cleaning in machine learning, a control system can be created that evaluates the degree of soiling of the filter cloth 5 after cleaning and updates the optimal amount of cleaning. This control system will be described in detail below with reference to Figure 11.

[0056] Figure 11 is a diagram illustrating the flow of a control system for a filter press according to another embodiment of the present invention. Model 54 is created by machine learning using training data consisting of photographic data of the filter cloth 5 surface after dewatering cake discharge, washing amount data during filter cloth 5 washing, and photographic data of the filter cloth 5 surface after washing. The training data is selected according to the situation from data obtained in advance through experiments, data used in past dewatering operations, data obtained at other machinery plants, etc. The control system 55 constructs Model 54 using the above training data according to a known machine learning algorithm.

[0057] After the dewatered cake is discharged during the dewatering operation of the filter press, the surface of the filter cloth 5 is photographed using the imaging device 50. The photographic data of the filter cloth 5 surface after the discharge of the dewatered cake, acquired by the imaging device 50, is input to the trained model 54. The control system 55 calculates the optimal value of the washing amount data during filter cloth washing according to the model 54 and outputs it from the model 54. The washing control of the filter cloth 5 is performed based on the output washing amount data.

[0058] After the cleaning of the filter cloth 5 is complete, the camera 50 takes another photograph of the filter cloth 5, and the photographic data of the filter cloth 5 surface after cleaning is input to the model 54. The control system 55 compares the difference between the photographic data of the filter cloth 5 surface after dewatering cake discharge and the photographic data of the filter cloth 5 surface after cleaning, input to the model 54, and determines whether there are any areas on the filter cloth 5 surface that are not sufficiently cleaned, thereby evaluating the appropriateness of the cleaning amount data output from the model 54 during filter cloth cleaning. If the cleaning amount data needs to be corrected based on the evaluation results, the model 54 is updated.

[0059] Over time, the surface of the filter cloth 5 changes in properties such as peelability and color due to prolonged operation. In addition, the properties and color of the raw liquid supplied to the filter press also change due to external factors such as season and time of day. Therefore, according to this embodiment, which uses machine learning to update the optimal washing amount data by acquiring image data of the filter cloth 5 surface, the washing efficiency of the filter cloth 5 can be maximized over a long period of time. This reduces the amount of washing water and the time required for washing, as well as extending the lifespan of the filter cloth 5. [Industrial applicability]

[0060] The filter cloth cleaning method and filter cloth cleaning control system for a filter press according to this invention can be applied to a filter press in which a pair of filter cloths are suspended between parallel filter plates, a raw liquid is supplied to a filtration chamber formed between the filter cloths for dewatering, and then the filter cloths are raised and lowered while being wound onto a lower return roll. Because the amount of water used for cleaning the filter cloths and the number of cleaning cycles can be appropriately controlled, cleaning water can be saved and the frequency of filter cloth replacement can be reduced. The filter press can be used not only for dewatering tap water and industrial water sludge, but also in production processes such as those in chemical plants. [Explanation of symbols]

[0061] 4 filter plates 5. Filter cloth 6. Filtration Chamber 20 Return Roll 21 Washing pipe 33 Branch pipe 50 Imaging device 52 Washing water pump 54 Models 55 Control Systems

Claims

1. In a filter press in which a pair of filter cloths (5, 5) are suspended between parallel filter plates (4, 4), and the raw liquid is supplied to a filtration chamber (6) formed between the filter cloths (5, 5) for dewatering, and then the filter cloths (5) are raised and lowered while being wrapped around a lower return roll (20), In advance, multiple color standards are set up to serve as indicators for determining the degree of soiling of the filter cloth (5) after the cake has been discharged, The amount of washing is set according to the standard for each color. The surface of the filter cloth (5) after the cake has been discharged is photographed with the camera (50). The color standard is determined from the acquired shooting data. The amount of water washed by the filter cloth (5) is controlled according to the color standard. A method for cleaning the filter cloth of a filter press, characterized by the features described above.

2. The amount of washing is, The number of times the filter cloth (5) is raised and lowered, the range of the filter cloth (5) being raised and lowered, the speed of the filter cloth (5) being raised and lowered, the opening degree of the washing pipe (21), and the rotation speed of the washing water pump (52) are set from at least one of these. The method for cleaning the filter cloth of a filter press according to feature 1.

3. The surface of the filter cloth (5) is divided into two or more sections, and the amount of washing is controlled according to the degree of soiling in each section. The method for cleaning the filter cloth of a filter press according to feature 2.

4. A valve is installed in a branch pipe (33) that branches off from the aforementioned washing pipe (21) to each filtration chamber (6) and sprays washing water onto the corresponding filter cloth (5). This branch pipe divides the parallel filtration chambers (6) into two or more, and the amount of washing is adjusted by adjusting the opening of the valve for each divided filter cloth (5). A method for cleaning the filter cloth of a filter press according to claim 2 or 3, characterized by the features described above.

5. A color standard is set as an indicator for determining the state of completion of the cleaning of the filter cloth (5). The surface of the filter cloth (5) after washing is photographed with the camera (50). From the acquired photographic data, the color standard after washing the filter cloth (5) is determined. If the captured data falls outside the range of the color standard after cleaning the filter cloth (5), control is performed to change at least one of the color standard after cake discharge, which is set in multiple stages, or the amount of cleaning set according to the color standard. The method for cleaning the filter cloth of a filter press according to feature 4.

6. A filter press control system (55) is provided which a pair of filter cloths (5, 5) are suspended between two parallel filter plates (4, 4), the raw liquid is supplied to a filtration chamber (6) formed between the filter cloths (5, 5) to dewater it, and then the filter cloths (5) are raised and lowered while being wrapped around a lower return roll (20), The system includes a model (54) constructed by machine learning using training data that includes photographic data of the surface of the filter cloth (5) after the dewatered cake has been discharged, data on the amount of washing during the washing of the filter cloth (5), and photographic data of the surface of the filter cloth (5) after washing the filter cloth (5). The control system (55) is The image data of the filter cloth (5) surface after dewatering the cake is input into the model (54), and the optimal value of the washing amount data during filter cloth (5) washing is calculated according to the model (54). Furthermore, the image data of the filter cloth (5) surface after washing is input into the model (54), the appropriateness of the washing amount data is evaluated, and the model (54) is updated based on the evaluation results. It is configured in such a way A filter press filter cloth cleaning control system characterized by the following:

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