Method and system for controlling the constant cake thickness of a filter press.

Abstract

This invention provides a method for controlling the constant cake thickness in a filter press by using a camera to image and analyze the thickness of the dewatered cake falling from an open filter plate, and then inferring the properties of the raw liquid from the cake thickness to perform optimal dewatering control. [Solution] A standard cake thickness of the dewatered cake and a change amount for increasing or decreasing the press-fitting control amount according to the difference in cake thickness between the standard cake thickness and the dewatered cake are set in advance in multiple stages. When the dewatered cake is discharged, the falling dewatered cake is photographed by the camera 50, the cake thickness of the dewatered cake is measured from the acquired photographic data, the difference in cake thickness between the measured cake thickness and the standard cake thickness is compared, the change amount is calculated from the cake thickness difference, and when dewatering the next batch, the press-fitting control is performed after increasing or decreasing the press-fitting control amount from the previous batch by the change amount, thereby always producing a dewatered cake with the optimal cake thickness.

Description

Technical Field

[0001] The present invention relates to an operation method for a filter press, and in particular, relates to a method and system for controlling cake thickness to be constant in a filter press, which analyzes the thickness of dewatered cake formed in a filter chamber, and performs operation control during dewatering operation to control the thickness of the dewatered cake to be constant.

Background Art

[0002] A filter press suspends a pair of filter cloths on a plurality of filter plates arranged in parallel to be openable and closable, and presses raw liquid into a filter chamber formed between the pair of filter cloths from a liquid supply plate fixed to the filter cloths to perform solid-liquid separation. After the dewatering process is completed, the filter plates are opened to discharge the dewatered cake.

[0003] Patent Document 1 discloses a filter press in which a pair of filter cloths is disposed between filter plates arranged in parallel to be openable and closable, and the filter cloths are moved up and down to discharge the dewatered cake adhered to the filter cloths downward.

[0004] Patent Document 2 discloses a measurement method for detecting the thickness of a cake layer by irradiating the dewatered cake layer with laser light of a constant intensity, and measuring the intensity of the irradiated laser light blocked by the dewatered cake layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The properties of the raw sap supplied to the filter press fluctuate constantly depending on the season, weather, time of day, etc. Without dewatering control tailored to the properties of the raw sap, it becomes difficult to produce a stable dewatered cake with a low moisture content or a dewatered cake that easily detaches from the filter cloth. While methods for analyzing the properties of the raw sap in the raw sap storage tank or coagulation mixing tank upstream of the filter press are well known, the resulting dewatered cake can sometimes be unstable due to the combination with the filter media, which is consumed over time.

[0007] As described in Patent Document 1, a typical filter press dewaters the raw liquid in the filtration chamber, then opens the filter plate to discharge the dewatered cake adhering to the filter cloth downwards. A conveying mechanism such as a belt conveyor is installed below, and the dewatered cake discharged from each filtration chamber is collected in a collection area by the conveying mechanism. The dewatered cake discharged from the filtration chamber to the conveying mechanism is crushed by the impact of the fall, so the thickness of the dewatered cake was measured manually by the supervisor.

[0008] Patent Document 2 describes a technique for measuring the thickness of a dewatered cake formed on a filter medium in a vacuum dewatering machine or the like. This technique can be performed by irradiating a laser beam from the side of the continuously moving filter medium, but it cannot be applied to filter presses that generate a dewatered cake in a sealed filtration chamber and discharge the dewatered cake downwards simultaneously with the opening of the filtration chamber.

[0009] The present invention provides a method for controlling the constant cake thickness in a filter press, which involves imaging and analyzing the thickness of the dewatered cake with a camera as the dewatered cake falls from an open filter plate, and then inferring the properties of the raw liquid from the cake thickness to perform optimal dewatering control. [Means for solving the problem]

[0010] The present invention relates to a filter press in which a pair of filter cloths are stretched between parallel filter plates, a raw liquid is supplied to a filtration chamber formed between the filter cloths for dewatering, and then the filter plates are opened to discharge the dewatered cake from the filtration chamber downwards. In this invention, a standard cake thickness of the dewatered cake and a change amount for increasing or decreasing the pressurization control amount according to the difference in cake thickness between the standard cake thickness and the dewatered cake are set in advance in multiple stages, the dewatered cake falling when it is discharged is photographed with a camera, the cake thickness of the dewatered cake is measured from the acquired photographic data, the difference in cake thickness between the measured cake thickness and the standard cake thickness is compared, the change amount is calculated from the cake thickness difference, and when dewatering the next batch, the pressurization control is performed after increasing or decreasing the pressurization control amount from the previous batch by the change amount, thereby enabling the production of a dewatered cake with the optimal cake thickness at all times.

[0011] Furthermore, the press-fit control amount can be set from at least one of the press-fit time, press-fit pressure, and press-fit flow rate to enable appropriate press-fit control.

[0012] Furthermore, since the imaging device is installed below the filtration chamber and to the side of the filter plate, it can accurately photograph the dewatered cake falling from the filtration chamber.

[0013] A filter press control system is configured to always generate a dewatered cake of optimal thickness by evaluating the appropriateness of the change amount data based on the evaluation results, and then updating the model based on the evaluation results, after which a pair of filter cloths are stretched between parallel filter plates, a raw liquid is supplied to a filtration chamber formed between the filter cloths for dewatering, and the filter plates are opened to discharge the dewatered cake from the filtration chamber downwards. The system includes a model constructed by machine learning using training data that includes cake thickness data of the dewatered cake and pressure control amount data. The control system creates cake thickness data from photographic data of the dewatered cake discharged from the filtration chamber during cake discharge, inputs the cake thickness data into the model, calculates the optimal value of the change amount data to increase or decrease the pressure control amount during dewatering of the next batch according to the model, and further evaluates the appropriateness of the change amount data from the cake thickness data created from photographic data of the dewatered cake discharged from the filtration chamber during cake discharge of the next batch. [Effects of the Invention]

[0014] The present invention enables actual measurement of the thickness of the dewatered cake, thereby allowing accurate estimation of the properties of the raw liquid. In addition, it becomes possible to control the press-fitting time, press-fitting pressure, and press-fitting flow rate according to the thickness of the dewatered cake, so that a stable and high-quality dewatered cake can be produced. By grasping the thickness of the dewatered cake after dewatering, control accuracy can be improved. [Brief Description of the Drawings]

[0015] [Figure 1] It is a schematic side view of the filter press according to the present invention. [Figure 2] Similarly, it is a front view of the filter plate. [Figure 3] Similarly, it is a perspective view of the filter cloth. [Figure 4] Similarly, it is a plan view of the main part of the filter press in which a pair of filter cloths are suspended between the filter plates. [Figure 5] Similarly, it is a schematic view of the filtration chamber. [Figure 6] It is a control flow of the filter press according to the present invention. [Figure 7] It is a diagram for explaining the flow of a control system of a filter press according to another embodiment of the present invention. [Modes for Carrying Out the Invention]

[0016] Figure 1 is a schematic side view of the filter press according to the present invention. In the filter press 1, a large number of filter plates 5··· are arranged in parallel on a pair of guide rails 4, 4 bridged between a front frame 2 and a rear frame 3. The rear frame 3 is supported with an opening / closing device 6 for opening and closing the filter plates 5···, and by tightening the filter plates 5··· with the opening / closing device 6, a filtration chamber 7 is formed between the adjacent filter plates 5, 5.

[0017] The front frame 2 is connected with a raw liquid supply pipe 8 communicating with each filtration chamber 7. By driving the raw liquid press-fitting pump 9, the raw liquid stored in the raw liquid storage tank 10 is press-fitted and supplied into each filtration chamber 7 through the raw liquid supply pipe 8, thereby generating a dewatered cake in the filtration chamber 7.

[0018] On one side surface of the front frame 2 and the rear frame 3, a side frame 12 is bridged below the row of filter plates 5, and an imaging device 50 is mounted on the side frame 12. When discharging the dehydrated cake generated in the filter chamber 7, the imaging device 50 can determine the thickness of the dehydrated cake by photographing the dehydrated cake at the moment it falls as the filter plates 5 are opened, from the side. The imaging device 50 only needs to be installed on the side frame 12 such that the dehydrated cake falling from any filter chamber 7 is positioned at the center of the imaging range, and it may be configured to always image the same filter chamber 7, or the imaging device 50 may be configured to be movable on the side frame 12, so that the filter chamber 7 to be imaged is changed for each batch.

[0019] It should be noted that a plurality of imaging devices 50 may be provided on the side frame 12 to simultaneously photograph the dehydrated cake discharged from several filter chambers 7, or the side frames 12, 12 may be bridged on both sides of the front frame 2 and the rear frame 3, and one imaging device 50 may be provided on each of the side frames 12, 12 to photograph both side surfaces of the dehydrated cake. Further, although the side frame 12 is provided for mounting the imaging device 50 in FIG. 1, by extending a member below the guide rail 4, the imaging device 50 may be suspended from the guide frame 4, and the side frame 12 may be omitted.

[0020] A control device 51 is connected to the imaging device 50, and imaging data captured by the imaging device 50 is transmitted to the control device 51. The control device 51 measures the thickness of the dehydrated cake by analyzing the imaging data. The control device 51 is also connected to the stock solution press-fitting pump 9, and performs press-fitting control in the press-fitting step of the next batch according to the measured thickness of the dehydrated cake.

[0021] FIG. 2 is a front view of the filter plate according to the present invention. A pair of guide rails 4,4 bridged between the front frame 2 and the rear frame 3 support the filter plate arms 13,13 of the filter plate 5. An upper bracket 14,14 erected on the top of the filter plate 5 supports the filter cloth drive shaft 15, and drive wheels 16,16 are fitted to both ends of the filter cloth drive shaft 15. In this embodiment, the drive wheels 16 use sprockets with gears on their outer circumference, and a drive chain 17 is wrapped around them. The filter cloth drive shaft 15 is linked to a slide shaft 18 that is arranged along the top of the parallel filter plates 5... and transmits driving force. A pair of return rolls 20,20 are supported on lower brackets 19,19 that hang down from the lower ends of both ends of the filter plate 5. A filtration bed 5a is formed in the center of the filter plate 5, with a raw liquid supply port 21 in the upper center and filtrate discharge ports 22 at both lower ends.

[0022] Figure 3 is a perspective view of the filter cloth according to the present invention. The filter cloth 23 suspended between the filter plates 5, 5 has a bag portion 24 formed by joining the upper edges of a pair of filter cloths 23, 23, and an upper filter cloth core 25 is inserted through it. Bag portions 26, 26 are also formed on the lower edges of the filter cloths 23, 23, and lower filter cloth cores 27, 27 are inserted through them. A stock solution supply plate 28 is sandwiched between the pair of filter cloths 23, 23, and the stock solution passage 30 of the stock solution supply plate 28 is joined to a through hole 29 that opens in the upper center of the filter cloth 23, and a liquid supply passage 31 is provided that branches off from the stock solution passage 30 of the stock solution supply plate 28 and supplies stock solution to the filtration surface of the filter cloth 23.

[0023] Figure 4 is a plan view of the main part of a filter press that suspends a pair of filter cloths between filter plates according to the present invention. A filter cloth drive shaft 15 is supported by upper brackets 14, 14 erected on the top of the filter plate 5, and a slide shaft 18 that transmits the driving force shown in Figure 2 is connected in conjunction with this filter cloth drive shaft 15. A pair of filter cloths 23, 23 are arranged between the parallel filter plates 5, 5... Drive chains 32 are connected to both ends of the upper filter cloth core 25 that suspends the pair of filter cloths 23, 23, and are wrapped around drive wheels 16, 16 fitted to the filter cloth drive shaft 15 on the top of the filter plate 5. The lower ends of the filter cloths 23, 23 suspended in front of and behind the filter plate 5 are wrapped around a pair of return rolls 20, 20 arranged below the filter plate 5, and the ends of the lower filter cloth cores 27, 27 inserted through the lower ends of the filter cloths 23 are connected to the other ends of the drive chains 32, 32, thereby suspending the filter cloths 23.... The drive force is transmitted from the slide shaft 18 shown in Figure 2 to the filter cloth drive shaft 15, causing the filter cloth 23 to move up and down in a seesaw-like motion.

[0024] When the parallel filter plates 5 are closed, the raw liquid supply plate 28 suspended from the filter cloth 23 is sandwiched between the front and rear filter plates 5, 5, forming a filtration chamber 7 between the pair of filter cloths 23, 23 stretched over the filtration bed 5a of the filter plates 5. The raw liquid supply port 21 formed in the filter plates 5, 5 is connected to the raw liquid passage 30 of the raw liquid supply plate 28, and the raw liquid is injected into the filtration chamber 7 from the liquid supply passage 31 of the raw liquid supply plate 28, performing solid-liquid separation on the filtration surface of the filter cloth 23.

[0025] Figure 5 is a schematic diagram of the filtration chamber according to the present invention. In the filtration chamber 7 formed by the closed filter plates 5,5, the solid-liquid separated cake is filled from the raw liquid supply plate 28 at the upper end of the filtration chamber 7 to the lower end of the filtration chamber 7, as shown in Figure 5(a). When the parallel filter plates 5... are opened, the cake falls straight down, as shown in Figure 5(b). At this time, if a part of the cake does not fall and adheres to the filter cloth 23, the drive force is transmitted from the slide shaft 11 to the filter cloth drive shaft 15, and the pair of filter cloths 17... are raised and lowered in a seesaw-like motion, which detaches the cake from the filter cloth 23 and causes it to fall.

[0026] The imaging device 50, mounted on the side frame 12, is positioned directly below the filtration chamber 7, which is the object to be photographed when the filter plate 5 is opened. It then captures the side of the falling cake from the front as the filter plate 5 is opened and photographs it. The timing of the photograph can be selected according to the situation, such as setting a predetermined time from the start of the opening operation of the filter plate 5, or installing a sensor that detects when the cake has passed above the imaging device 50. In addition, the falling cake may be photographed multiple times.

[0027] The image data acquired by the imaging device 50 is sent to the control device 51. The control device 51 analyzes the cake thickness from the image data and performs press-fit control to achieve the optimal cake thickness for the next batch of dewatering. The press-fit control is performed by a press-fit control amount set by at least one of the press-fit time, press-fit pressure, and press-fit flow rate. The reference cake thickness, which is the optimal cake thickness for dewatered cake, and the press-fit control amount at the reference cake thickness are set in advance through experiments and tests as the initial press-fit control amount. Furthermore, multiple levels of change are set to increase or decrease the press-fit control amount according to the difference in cake thickness from the reference cake thickness.

[0028] The cake thickness is measured from the image data of the dewatered cake discharged from the filtration chamber 7 during the dewatering operation, and the difference between the measured cake thickness and the standard cake thickness is compared. A predetermined change amount is calculated from the cake thickness difference, and the pressure control amount performed during the dewatering of the previous batch is increased or decreased by this change amount before performing the pressure control during the dewatering of the next batch.

[0029] Specifically, when the measured cake thickness is thinner than the reference cake thickness, during the dehydration of the next batch, the press-filling time is extended, or the press-filling pressure and the press-filling flow rate are increased, or these press-filling control variables are adjusted in combination so as to increase the cake thickness. When the measured cake thickness is thicker than the reference cake thickness, during the dehydration operation of the next batch, the press-filling time is shortened, or the press-filling pressure and the press-filling flow rate are decreased, or these press-filling control variables are adjusted in combination so as to reduce the cake thickness. When the cake thickness is within the range of the reference cake thickness, dehydration may be performed with the same press-filling time, press-filling pressure, and press-filling flow rate as in the previous batch. As a result, even if a problem occurs in the thickness of the dehydrated cake due to factors such as the properties of the stock solution, press-filling control can be performed to achieve the optimum cake thickness during the dehydration operation of the next batch, so that a high-quality dehydrated cake can always be produced.

[0030] Note that in the present embodiment, the imaging device 50 performs imaging only in an arbitrary filter chamber 7, but a plurality of imaging devices 50 may be provided in the row direction of the filter plates 5···, and each piece of imaging data may be analyzed by the control device 51 to average the cake thickness. In addition, by providing a rack on the side frame 12 and a pinion at the lower end of the imaging device 50, the imaging device 50 can travel on the side frame in the row direction of the filter plates 5···, so that the imaging device 50 can be moved directly below all the filter chambers 7. Thereby, the filter chamber 7 for determining the cake thickness for each batch can be arbitrarily selected.

[0031] Further, although the filter press 1 described in the present embodiment adopts a system in which the filter cloth 23 moves up and down, the thickness of the dehydrated cake can be similarly measured in a system in which the filter cloth 23 is fixed at the suspended position, or a system in which an endless filter cloth 23 is looped around. [Examples]

[0032] Figure 6 is a flowchart of the operation method of the filter press according to the present invention. <A. Initial Setting> In advance, the reference cake thickness of the dewatered cake and the press-in control amount at that time are set as the initial press-in control amount through tests, experiments or the like. Further, the variation amount for increasing or decreasing the press-in control amount according to the cake thickness difference from the reference cake thickness is set in a plurality of stages. The press-in control amount and the variation amount are set from at least one of press-in time, press-in pressure, and press-in flow rate.

[0033] <B. Dewatering> The row of filter plates 5 is closed by the opening / closing device 6, and the stock solution is press-fed from the stock solution press-in pump 9 into the filter chamber 7 formed between the closed filter plates 5, 5. The filtrate passes through the filter cloth 23 and is discharged to the outside, and the solid matter captured by the filter cloth 23 is dewatered while forming a cake layer.

[0034] During the first dewatering operation, the stock solution is press-fed with the initial press-in control amount. In the second and subsequent dewatering operations, the press-in control is performed after the variation amount calculated in the variation amount calculation step described later is reflected in the press-in control amount performed during the dewatering of the previous batch.

[0035] <C. Cake Discharge> After the completion of dewatering, the row of filter plates 5 is opened by the opening / closing device 6, so that the cake in the filter chamber 7 falls downward. The cake remaining in the filter chamber 7 without peeling off from the filter cloth 23 is discharged by operating the driving device 12 to cause the filter cloth 23 to travel downward.

[0036] <D. Cake Photography> The dewatered cake at the moment of falling from between the filter plates 5 by the opening / closing device 6 is photographed by the photographing device 50 disposed on the lower side surface of the row of filter plates 5. The photographing device 50 can accurately photograph the thickness of the dewatered cake by capturing and photographing the side surface of the dewatered cake from the front. The timing to start photographing can be selected according to the situation, such as presetting a predetermined time from the start of the plate opening operation of the filter plates 5, or providing a sensor above the photographing device 50 to detect that the cake has passed therethrough. In addition, the falling cake may be photographed a plurality of times.

[0037] <E. Cake Thickness Measurement> 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 measure the cake thickness of the dehydrated cake. As a method for measuring the cake thickness, the thickness may be measured only at a predetermined position on the dehydrated cake, or the thickness may be measured at a plurality of positions and averaged. Further, the cake thickness may be measured using a plurality of sets of imaging data by performing imaging a plurality of times on the falling dehydrated cake.

[0038] <F. Variation Calculation> The measured cake thickness is compared with a reference cake thickness, and a preset variation of the press-in control amount is calculated according to the cake thickness difference. The variation is a value that increases or decreases the press-in control amount performed during dehydration of the previous batch to be reflected in the press-in control of the dehydration operation of the next batch. When the measured cake thickness is thinner than the reference cake thickness, the variation increases the press-in control amount so as to increase the cake thickness, and when the measured cake thickness is thicker than the reference cake thickness, the variation decreases the press-in control amount so as to reduce the cake thickness. When the measured cake thickness is within the range of the reference cake thickness, it is determined that the press-in control amount is appropriate, and the dehydration operation may be performed in the next batch with the same press-in control amount as in the previous batch, and the variation is 0.

[0039] <G. Filter Cloth Cleaning> By spraying cleaning water onto the filter cloth 23 while moving the filter cloth up and down, deposits remaining on the surface of the filter cloth 23 are peeled off.

[0040] <B. Dehydration> When the cleaning of the filter cloth 23 is completed, the filter plate 5 row is closed again by the opening / closing device 6, and the stock solution is supplied to the filter chamber 7 to perform dehydration. The press-in control amount at this time is a value obtained by increasing or decreasing the variation with respect to the press-in control amount performed in the previous batch. When the cake thickness is thin, at least one of the press-in time, the press-in pressure, and the press-in flow rate is increased, and when the cake thickness is thick, it is decreased. When the cake thickness is optimal, the press-in control amount is not increased or decreased.

[0041] In this way, since it is possible to measure the thickness of the dehydrated cake every batch and constantly adjust the press-in control amount, it is possible to stably produce a dehydrated cake with a uniform thickness.

[0042] Furthermore, when using a compression-type filter press 1 in which a diaphragm is attached to the filtration bed 5a surface of the filter plate 5, the compression control amount may be configured to be adjustable in addition to the injection control amount.

[0043] As another embodiment of the present invention, by using machine learning techniques on the cake thickness data and press-fit control amount data of the dewatered cake, a control system can be created that determines whether the cake thickness of the dewatered cake generated during the dewatering operation is the optimal cake thickness, calculates the change in the press-fit control amount for the next batch, and also determines the appropriateness of the press-fit control amount from the cake thickness of the dewatered cake generated in the next batch, and updates the optimal value of the change. This control system will be described in detail below with reference to Figure 7.

[0044] Figure 7 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 using machine learning with training data consisting of cake thickness data and press-fit control amount data for dewatered cakes. The training data is obtained in advance as continuous data from multiple batches of dewatering operations through experiments or tests. Model 54 is constructed according to a known machine learning algorithm and is capable of outputting change amount data that increases or decreases the press-fit control amount in the dewatering operation of the next batch, based on the input cake thickness data.

[0045] During the dewatering operation using a filter press and the discharge of the dewatered cake, the falling dewatered cake is photographed by the imaging device 50. From the photographic data of the dewatered cake captured by the imaging device 50, the control system 55 creates cake thickness data, which is then input into the trained model 54. The control system 55 calculates the optimal value of the change amount to adjust the press-fit control amount in the dewatering operation of the next batch according to the model 54, and outputs it from the model 54. Based on the output change amount data, the press-fit control amount is increased or decreased by the change amount in the dewatering operation of the next batch, and press-fit control is performed.

[0046] After performing a dewatering operation based on the press-fit control amount adjusted by the output change amount data, the dewatered cake is photographed again as it falls during discharge. The photographic data acquired here is used to calculate the change amount of the press-fit control amount during the dewatering operation of the next batch, as with the previous batch. In addition, it is used to determine whether the cake thickness was within the optimal range based on the press-fit control amount used during the dewatering of the previous batch. If the determination indicates that the cake thickness of the dewatered cake in the previous batch was not within the optimal range, the change amount is evaluated as not being appropriate, and Model 54 is updated to correct the change amount data.

[0047] In this embodiment, cake thickness data is used to train Model 54, but the image data of the dehydrated cake captured by the imaging device 50 may also be used to train Model 54 directly. In that case, Model 54 will analyze the image data to obtain cake thickness data.

[0048] Furthermore, although the thickness of the dewatered cake produced in the filtration chamber 7 varies depending on the properties of the raw liquid and other factors such as temperature, it is possible to estimate the properties of the raw liquid by actually measuring the cake thickness of the dewatered cake in each batch. In addition, the relationship between the cake thickness and the injection control amount can be constantly updated and retrained in the model 54, making the control system 55 capable of responding to changes in cake thickness due to various factors. [Industrial applicability]

[0049] The method and system for controlling the constant cake thickness of a filter press according to this invention are applicable not only to filter presses with a lifting filter cloth, but to various other filter presses. Furthermore, they are applicable to other dewatering devices as well, as long as they have a configuration that allows for imaging in the thickness direction of the dewatered cake, and are not limited to filter presses. Filter presses 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]

[0050] 1. Filter Press 5 filter plate 7 Filtration Chamber 23 filter cloth 50 Imaging device 54 Models

Claims

1. In a filter press (1) in which a pair of filter cloths (23) are stretched between two parallel filter plates (5), and the raw liquid is supplied to a filtration chamber (7) formed between the filter cloths (23) to dewater it, and then the filter plates (5) are opened to discharge the dewatered cake from the filtration chamber (7) downwards, The standard cake thickness of the dewatered cake and the amount of change that increases or decreases the press-fitting control amount according to the difference in cake thickness between the standard cake thickness and the standard cake thickness are set in multiple stages in advance. The dehydrated cake falling during the discharge of the dehydrated cake is photographed by the camera (50). The cake thickness of the dehydrated cake was measured from the acquired photographic data. The difference in cake thickness between the measured cake thickness and the standard cake thickness was compared. The amount of change is calculated from the difference in cake thickness, During the dehydration of the next batch, the injection control is performed after increasing or decreasing the injection control amount from that of the previous batch by the same amount. A method for controlling the cake thickness of a filter press, characterized by the following features.

2. The press-fit control amount is set from at least one of the press-fit time, press-fit pressure, and press-fit flow rate. The method for controlling the cake thickness of a filter press according to feature 1.

3. The aforementioned imaging device is located below the filtration chamber (7) and to the side of the row of filter plates (5). The method for controlling the cake thickness of a filter press according to feature 2.

4. A filter press control system comprising a pair of filter cloths (23) stretched between two parallel filter plates (5), a filtration chamber (7) formed between the filter cloths (23) into which the raw liquid is supplied for dewatering, and then the filter plates (5) are opened to discharge the dewatered cake in the filtration chamber (7) downwards, The system includes a model (54) constructed by machine learning using training data that includes dewatered cake thickness data and press-fit control amount data. The control system is Cake thickness data is created from the image data of the dewatered cake discharged from the filtration chamber (7) during cake discharge. The cake thickness data is input into model (54), and the optimal value of the change amount data for increasing or decreasing the pressurization control amount during dehydration of the next batch is calculated according to model (54). Furthermore, the appropriateness of the change amount data is evaluated from the cake thickness data created from the image data of the dewatered cake discharged from the filtration chamber (7) during the next batch of cake discharge, and the model (54) is updated based on the evaluation results. A filter press cake thickness constant control system characterized by being configured as follows.

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