Dehydration Treatment System

Abstract

To provide a dehydration treatment system that can automate overall control by automatically determining whether or not sludge before dehydration is suitable for dehydration, by simple processing.SOLUTION: A dehydration treatment system 1 includes a coagulation tank 23, a concentration device 3, a speed measurement device 4, a determination device 61, and a dehydration device 5. The coagulation tank 23 is supplied with sludge and a coagulant, thereby producing coagulated floc CF in which sludge is coagulated. The concentration device 3 causes the coagulated floc CF to flow down and concentrate the coagulated floc CF. The speed measurement device 4 measures a flow speed of the coagulated floc CF flowing down the concentration device 3. The determination device 61 determines that the coagulated floc CF is suitable for dehydration if the flow speed of the floc CF measured by the speed measurement device 4 is equal to or lower than a concentration reference value. The dehydration device 5 dehydrates the coagulated floc CF.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a dehydration treatment system that thickens and dehydrates sludge. [Background technology]

[0002] Sludge generated from sewage treatment facilities or septic tanks is dehydrated to be used as a fuel additive in incineration facilities within the facility or in other waste treatment facilities, etc. Sludge dehydration is carried out by sequentially carrying out a sludge flocculation process, a thickening process of the flocculated sludge, and a dehydration process of the thickened sludge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-146614 [Patent Document 2] Patent No. 4238983 Summary of the Invention [Problem to be solved by the invention]

[0004] In a dehydration system that dehydrates sludge, a determination is made before the dehydration process as to whether the concentrated sludge is suitable for dehydration. The result of this determination is used to control the equipment that constitutes the dehydration system. However, the determination of whether the concentrated sludge is suitable for dehydration requires a visual determination by an operator of the dehydration system, which makes it difficult to automate the control of the dehydration system.

[0005] The inventions disclosed in Patent Documents 1 and 2 measure the size of concentrated sludge and determine whether the concentrated sludge is suitable for dewatering based on the measurement results. However, determining whether the concentrated sludge is suitable for dewatering based on the size of the concentrated sludge is complicated because the shape of the sludge changes during the concentration process, or because the process of calculating the size of the concentrated sludge is complicated, and this still makes it difficult to automate a dewatering treatment system.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a dehydration treatment system that can automate the overall control by automatically determining, through a simple process, whether the sludge before dehydration is suitable for dehydration in a dehydration treatment system that concentrates and dehydrates sludge. [Means for solving the problem]

[0007] According to one aspect of the present invention, a dewatering treatment system is a dewatering treatment system that concentrates and dewaters sludge, and is mainly characterized by comprising: a coagulation tank that produces coagulated flocs by supplying the sludge and a coagulant that coagulates the sludge; a concentrating device that causes the coagulated flocs to flow downward and concentrate the coagulated flocs; a velocity measuring device that measures the flow rate of the coagulated flocs flowing downward through the concentrating device; a determining device that determines that the concentrated coagulated flocs are suitable for dewatering if the flow rate is equal to or less than a concentration reference value that is a reference value for determining whether the concentrated coagulated flocs are suitable for dewatering; and a dewatering device that dewaters the concentrated coagulated flocs. [Effects of the Invention]

[0008] According to the dehydration treatment system of the present invention, it is possible to automatically determine whether or not the sludge before dehydration is suitable for dehydration through a simple process, thereby automating the control of the dehydration treatment system. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a diagram showing an outline of a dehydration treatment system according to an embodiment. [Figure 2] FIG. 2 is a diagram showing details of a concentrating device of the dehydration treatment system according to the embodiment. [Figure 3A] FIG. 2 is a diagram showing a first image captured by an imaging device in the embodiment. [Figure 3B] FIG. 10 is a diagram showing a second image captured by the imaging device in the embodiment. [Figure 4] 1 is a view of the top surface of an inclined screen in an embodiment, viewed from a direction perpendicular to the top surface of the inclined screen. FIG. [Figure 5] 1 is a graph showing the relationship between the moisture content of dewatered sludge dewatered in a dewatering device and the flow rate of flocs flowing down through a concentrating device in an embodiment. [Figure 6] 1 is a graph showing the relationship between the polymer injection rate into the coagulation tank and the flow rate of coagulated flocs flowing down through the concentration device in an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. The same or corresponding parts shown in the drawings will be denoted by the same reference numerals. The description of the parts denoted by the same reference numerals will not be repeated.

[0011] An outline of a dehydration system 1 according to an embodiment will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing an outline of the dehydration system 1 according to an embodiment. Figure 2 is a diagram showing details of a concentrating device 3 of the dehydration system 1 according to an embodiment.

[0012] Sludge is supplied to a dehydration treatment system 1 shown in Fig. 1. The dehydration treatment system 1 performs a dehydration treatment on the supplied sludge.

[0013] In the dehydration treatment, first, a flocculation step is carried out to flocculate the sludge supplied to the dehydration treatment system 1. The sludge flocculated in the flocculation step is referred to as "flocculated floc CF." In the dehydration treatment, a concentration step is carried out to concentrate the flocculated floc CF. In the concentration step, the flocculated floc CF flows down a concentration screen and is separated from the filtrate, and the flocculated floc CF is concentrated. Finally, in the dehydration treatment, a dehydration step is carried out to dehydrate the concentrated flocculated floc CF. The flocculated floc CF dewatered in the dehydration step is referred to as "dewatered sludge."

[0014] Dewatered sludge is used, for example, as a combustion improver in incineration facilities or waste treatment facilities. Therefore, the "dewatered sludge moisture content," which is the amount of water contained in the dewatered sludge, must be below a standard determined depending on the application. Specifically, when used as a combustion improver in incineration facilities or waste treatment facilities, the standard for the dewatered sludge moisture content is 70%. The moisture content of the dewatered sludge is below the standard when the flocculated flocs CF concentrated in the concentration step are suitable for dewatering. Therefore, by determining whether the flocculated flocs CF concentrated in the concentration step are suitable for dewatering, it is possible to determine from the determination result whether the moisture content of the dewatered sludge is below the standard. Furthermore, by controlling the equipment constituting the dewatering treatment system 1 based on the state of the flocculated flocs CF concentrated in the concentration step, flocculated flocs CF in a state suitable for dewatering can be produced by concentration.

[0015] As shown in Fig. 1, the dewatering treatment system 1 includes a mixing tank 21 to which sludge and a dewatering aid are supplied, a sludge supply pump 22 that discharges the sludge from the mixing tank 21, a coagulation tank 23 to which the sludge discharged to the sludge supply pump 22 is supplied, a coagulant supply pump 24 that supplies a coagulant to the coagulation tank 23, a thickener 3 that thickens coagulated flocs CF produced by supplying the coagulant to the sludge in the coagulation tank 23, and a dewatering device 5 that dewaters the coagulated flocs CF thickened in the thickener 3. The mixing tank 21, the sludge supply pump 22, the coagulation tank 23, and the coagulant supply pump 24 perform a coagulation process. The thickener 3 performs a concentration process. The dewatering device 5 performs a dewatering process.

[0016] The mixing tank 21 has a mixing tank 211 to which sludge and dehydration aid are supplied, and a mixing mixer 212 that mixes the sludge and dehydration aid supplied to the mixing tank 211. The sludge and dehydration aid are mixed by being stirred by the mixing mixer 212. Sludge mixed with a dehydration aid is more likely to flocculate than sludge not mixed with a dehydration aid. Dehydration aids include, for example, fibrous materials, inorganic flocculants, pH adjusters, and wood flour.

[0017] The sludge supply pump 22 is a pump that sends the sludge mixed with the dewatering aid in the mixing tank 21 to the coagulation tank 23. In this way, the sludge is supplied to the coagulation tank 23.

[0018] Sludge is supplied to the coagulation tank 23 from the mixing tank 21 via a sludge supply pump 22. A coagulant is also supplied to the coagulation tank 23 from a coagulant supply pump 24. The coagulant supply pump 24 is a pump that sends the coagulant to the coagulation tank 23. The coagulant is a polymer that coagulates the sludge when added to the sludge. The polymer of the coagulant includes an organic polymer or an inorganic polymer.

[0019] The coagulation tank 23 has a coagulation tank 231 to which sludge and a coagulant are supplied, and a coagulation tank agitator 232 that agitates the sludge and the coagulant supplied to the coagulation tank 231. The sludge and the coagulant supplied to the coagulation tank 231 are mixed by being agitated by the coagulation tank agitator 232. As a result, coagulated flocs CF are produced. The coagulated flocs CF produced in the coagulation tank 231 are dispersed and flow within the coagulation tank 231.

[0020] As shown in FIG. 2, the thickener 3 has a thickener inlet pipe 31 into which the flocculated flocs CF produced in the coagulation tank 23 flow, an inclined screen 32 connected to the thickener inlet pipe 31, and a thickener outlet pipe 33 connected to the inclined screen 32.

[0021] The thickener inlet pipe 31 is a pipe that opens horizontally at both ends. One end of the thickener inlet pipe 31 is connected to the top of the flocculation tank 231. The interior of the flocculation tank 231 and the interior of the thickener inlet pipe 31 are in communication. The other end of the thickener inlet pipe 31 is connected to the inclined screen 32.

[0022] As described above, the flocculated flocs CF generated in the flocculation tank 231 are fluidized and dispersed within the flocculation tank 231. By continuously supplying sludge to the flocculation tank 231, the liquid level of the sludge within the flocculation tank 231 rises. When the liquid level of the sludge within the flocculation tank 231 rises to the position of the thickener inlet piping 31, the liquid components of the sludge and the flocculated flocs CF flow into the thickener inlet piping 31. After flowing into the thickener inlet piping 31, the liquid components of the sludge and the flocculated flocs CF flow toward the inclined screen 32.

[0023] The inclined screen 32 has an inlet section into which the flocs CF flow and an outlet section from which the flocs CF that have flowed into the inlet section flow out. The inclined screen 32 is inclined so that the outlet section is located lower than the inlet section. Here, the most upstream side of the inlet section is referred to as the inlet end 32A. The most downstream side of the outlet section is referred to as the outlet end 32B.

[0024] The liquid components of the sludge and the flocs CF that have flowed toward the inclined screen 32 flow into the inlet end 32A. The inlet end 32A is connected to the lower part of the other end of the above-mentioned thickener inlet piping 31. Note that the inlet end 32A does not need to be connected to the thickener inlet piping 31 as long as the liquid components of the sludge and the flocs CF that have flowed toward the inclined screen 32 flow into it.

[0025] The inclined screen 32 is a screen that filters the liquid components of the sludge and the flocculated flocs CF as they flow downward. The liquid components of the sludge and the flocculated flocs CF flow into the inlet end 32A and then onto the upper surface of the inclined screen 32. The liquid components of the sludge and the flocculated flocs CF that have flowed onto the upper surface of the inclined screen 32 flow downward along the upper surface of the inclined screen 32. As the liquid components of the sludge flow downward along the upper surface of the inclined screen 32, they pass through the inclined screen 32 from the upper surface to the lower surface of the inclined screen 32 and fall to the bottom of the inclined screen 32. The liquid components of the sludge that pass through the inclined screen 32 are called "concentrated filtrate."

[0026] On the other hand, the flocs CF that have flowed onto the upper surface of the inclined screen 32 flow down the upper surface of the inclined screen 32 without passing through the inclined screen 32. As the flocs CF flow down the upper surface of the inclined screen 32, the liquid components of the sludge are separated from the flocs CF and the flocs CF are concentrated. The concentrated flocs CF flow out from the outlet end 32B. The flocs CF that have flowed out from the outlet end 32B head towards the thickener outlet piping 33.

[0027] The concentrator outlet piping 33 is a piping having openings at both ends in the vertical direction. The concentrator outlet piping 33 is arranged so that the flocs CF flowing out from the outlet end 32B flow into the inside of the concentrator outlet piping 33 through openings provided at the upper end of the concentrator outlet piping 33. The upper end of the concentrator outlet piping 33 is connected to the outlet end 32B of the inclined screen 32. The lower end of the concentrator outlet piping 33 is connected to the dehydrator 5. The concentrator outlet piping 33 does not need to be connected to the outlet end 32B as long as the flocs CF flowing out from the outlet end 32B flow into the inside of the concentrator outlet piping 33. In addition, in the embodiment, the inlet end 32A has been described as the inlet portion, but the inlet portion is not limited to the inlet end 32A as long as it is a portion into which the flocs CF flow. Similarly, the outlet portion is not limited to the outlet end 32B as long as it is a portion into which the flocs CF flow out.

[0028] The flocs CF heading toward the thickener outlet piping 33 flow into the inside of the thickener outlet piping 33. The flocs CF that have flowed into the inside of the thickener outlet piping 33 flow into the dehydrator 5.

[0029] The dehydrator 5 dehydrates the flocs CF concentrated in the concentrator 3, and separates the dehydrated sludge from the "dehydrated filtrate," which is the liquid component of the concentrated flocs CF. The dehydrator 5 is, for example, a screw press dehydrator.

[0030] 2 to 6, a detailed description will be given of a determination as to whether the flocculated flocs CF concentrated by the concentrator 3 in the dewatering system 1 according to the embodiment are suitable for dewatering, and of control of each of the components of the dewatering system 1 based on the state of the flocculated flocs CF concentrated by the concentrator 3. FIG. 3A is a diagram showing a first image M1 captured by the image capture device 41 according to the embodiment. FIG. 3B is a diagram showing a second image M2 captured by the image capture device 41 according to the embodiment. FIG. 4 is a diagram showing the top surface of the inclined screen 32 as viewed from a direction perpendicular to the top surface of the inclined screen 32 according to the embodiment. FIG. 5 is a graph showing the relationship between the moisture content of dewatered sludge dewatered by the dewatering device 5 and the flow rate of the flocculated flocs CF flowing down through the concentrator 3 according to the embodiment. FIG. 6 is a graph showing the relationship between the polymer injection rate into the coagulation tank 23 and the flow rate of the flocculated flocs CF flowing down through the concentrator 3 according to the embodiment.

[0031] As shown in FIG. 2, the dewatering system 1 further includes a velocity measuring device 4 that measures the flow velocity of the flocs CF flowing down the concentrating device 3, a determining device 61 that determines whether the flocs CF concentrated in the concentrating device 3 are suitable for dewatering based on the measurement results of the velocity measuring device 4, an estimating device 62 that estimates the water content of the dewatered sludge based on the measurement results of the velocity measuring device 4, and a system control device 63 that controls each of the devices that make up the dewatering system 1 based on the estimation results of the estimating device 62.

[0032] The velocity measuring device 4 has at least one image capturing device 41 arranged so as to be able to capture an image of the upper surface of the inclined screen 32, and a velocity calculator 42 to which the image captured by the image capturing device 41 is input. The velocity measuring device 4 calculates the flow velocity of the flocs CF flowing down the upper surface of the inclined screen 32 from the image captured by the image capturing device 41. As a result, information on the flow velocity of the flocs CF can be used to determine whether the flocs CF concentrated in the concentration device 3 are suitable for dewatering, and to control the equipment that constitutes the dewatering treatment system 1.

[0033] The image capture device 41 captures images of the flocs CF flowing down the top surface of the inclined screen 32. The image capture device 41 is, for example, a camera that records images such as videos or photographs.

[0034] 3A and 3B, an image captured by the imaging device 41 includes information about the time at which the image was captured by the imaging device 41. Hereinafter, an image captured by the imaging device 41 at a first time will be referred to as a first image M1, an image captured by the imaging device 41 at a second time will be referred to as a second image M2, and an image captured by the imaging device 41 at an Nth time (N is an integer equal to or greater than 3) will be referred to as an Nth image.

[0035] The velocity calculator 42 calculates the flow velocity of the flocs CF flowing down the upper surface of the inclined screen 32 based on two images: a first image M1 (FIG. 3A) captured by the image capture device 41 at a first time, a second image M2 (FIG. 3B) captured by the image capture device 41 at a second time, and an Nth image captured by the image capture device 41 at an Nth time. The velocity calculator 42 is, for example, a terminal having a processor such as an MPU (Micro Processing Unit) and a CPU (Central Processing Unit), and memories such as a ROM (Read Only Memory) and a RAM. The velocity calculator 42 calculates the flow velocity of the flocs CF by having the processor execute a velocity calculation program stored in the ROM. This configuration is also the same in the determination device 61, the estimation device 62, the system control device 63, and the cleaning control device 72, which will be described later.

[0036] The velocity calculator 42 has a position definition unit 421 that defines the positions of the flocs CF in the first image M1, the second image M2, and the Nth image; a distance calculation unit 422 that calculates the distance traveled by the flocs CF based on the positions of the flocs CF defined by the position definition unit 421; a time calculation unit 423 that calculates the time that has passed as the flocs CF flow down based on the photographing time recorded in the Nth image input from the image pickup device 41; and a velocity calculation unit 424 that calculates the velocity of the flocs CF flowing down based on the distance traveled by the flocs CF calculated by the distance calculation unit 422 and the time that has passed as the flocs CF flow down calculated by the time calculation unit 423.

[0037] Calculation of the flow velocity of flocs CF by the velocity calculator 42 will be described with reference to the first image M1 shown in FIG. 3A and the second image M2 shown in FIG. 3B. Hereinafter, for convenience of explanation, the downward direction in the drawings shown in FIGS. 3A and 3B will be referred to as the downstream direction. The direction opposite to the downstream direction will be referred to as the upstream direction. The direction perpendicular to the downstream direction will be referred to as the left-right direction. In FIGS. 3A and 3B, flocs CF flow down from the upstream direction to the downstream direction. Furthermore, any position in the first image M1 and the second image M2 will be expressed by a Cartesian coordinate system in the up-downstream direction and the left-right direction. Specifically, when any point P11 is defined in the first image M1, the left-right position of P11 will be expressed by X1, and the up-downstream position of P11 will be expressed by Y11. Coordinates expressed by the same character indicate the same position in each direction.

[0038] As shown in FIG. 3A, the position definition unit 421 defines a first position of the agglomerated flocks CF at a first time based on the first image M1. The first position is defined by setting a first point cloud consisting of a plurality of points on the boundary between the agglomerated flocks CF and areas other than the agglomerated flocks CF. Specifically, points P11, P12, and P13 are defined as the first point cloud. The positions of the respective points are (X1, Y11) for point P11, (X2, Y21) for point P12, and (X3, Y31) for point P13. The positions of such a first point cloud are defined as the first position.

[0039] The position definition unit 421 defines a second position of the flocs CF at the second time based on the second image M2, as shown in FIG. 3B. The second position is defined by setting a second point cloud consisting of a plurality of points along the downstream flow direction of the flocs CF and on the boundaries of the flocs CF and other than the flocs CF located downstream of each of the points constituting the first point cloud. Specifically, the second point cloud is composed of point P21 defined downstream of point P11, point P22 defined downstream of point P12, and point P23 defined downstream of point P13. The positions of the points constituting the second point cloud are (X1, Y12) for point P21, (X2, Y22) for point P22, and (X3, Y32) for point P23. The positions of these points in the second point cloud are defined as the second position.

[0040] Here, the flocs CF flow downward from the upstream direction to the downstream direction, with only slight movement in the left-right direction. Therefore, as described above, by the position definition unit 421 defining the first position and the second position, it is possible to define points in the second image M2 corresponding to any points of the flocs CF set in the first image M1. As a result, even if the shape of the flocs CF changes as they flow downward, the change in their position can be accurately defined by simple processing.

[0041] 2 calculates the distance from the first position to the second position based on the first position and the second position defined by the position definition unit 421. The distance from the first position to the second position is calculated by finding the distance from each of the points constituting the first point group to each of the points in the second point group that correspond to each of the points constituting the first point group.

[0042] The time calculation unit 423 calculates the elapsed time from the first time to the second time based on the first time and the second time.

[0043] The velocity calculation unit 424 calculates the flow-down velocity of the flocs CF by dividing the distance from the first position to the second position calculated by the distance calculation unit 422 by the time from the first time to the second time calculated by the time calculation unit 423. The flow-down velocity of the flocs CF calculated by the velocity calculation unit 424 is output to the determination device 61 and the estimation device 62 as a measurement value measured by the velocity measurement device 4.

[0044] The velocity calculator 42 calculates the flow rate of one floc CF at multiple times, the flow rate of multiple flocs CF, or the flow rate of one floc CF at multiple times and the flow rate of multiple flocs CF, based on multiple images captured at different times by the image capture device 41. Therefore, the velocity calculator 42 calculates multiple flow rates. This provides multiple pieces of information on the flow rate of flocs CF that can be used to determine whether the flocs CF concentrated in the concentration device 3 are suitable for dewatering and to control the equipment that makes up the dewatering treatment system 1, improving the accuracy of the determination and the accuracy of the control.

[0045] The determination device 61 receives as input the measured value of the flow velocity of the flocs CF measured by the velocity measuring device 4. If a determination value, which will be described later and is calculated based on the measured value of the flow velocity, is equal to or less than a concentration reference value, the determination device 61 determines that the flocs CF concentrated in the concentrating device 3 are suitable for dewatering. Here, the concentration reference value is a reference value for determining whether the flocs CF concentrated in the concentrating device 3 are suitable for dewatering. The determination device 61 performs a simple process of comparing the determination value with the concentration reference value, thereby eliminating the need for an operator to make the determination. Therefore, the determination is performed automatically by a simple process.

[0046] The determination device 61 determines whether the concentrated flocs CF are suitable for dewatering based on the measured value of the flow velocity of the flocs CF in at least a portion of the range R, which is 90% or less from the outlet end 32B, within the range from the inlet end 32A to the outlet end 32B. As shown in FIG. 4, the range R is determined based on the total length FL, which is the length from the inlet end 32A to the outlet end 32B in the longitudinal direction of the inclined screen 32, and the outlet end 32B. If the total length FL is 100%, the range R is the portion included from the outlet end 32B to a range reference position RP that is 90% of the total length FL. In the range R, the liquid components of the sludge and the surfaces of the flocs CF are less disturbed and are stable. As a result, the influence of measurement errors of the flow velocity of the flocs CF due to the liquid components of the sludge and the surface disturbance of the flocs CF on the determination can be reduced.

[0047] 2 preferably makes a determination based on the measured value of the flow rate of flocs CF in the following portions of the range R. First, the determination device 61 preferably makes a determination based on the measured value of the flow rate of flocs CF in a first portion R1 of the range R, which is included from the outflow end 32B to a range setting position RP1 that is 80% of the total length FL. Second, the determination device 61 preferably makes a determination based on the measured value of the flow rate of flocs CF in a second portion R2 of the range R that is as wide as possible and excludes a certain portion from the outflow end 32B, based on an intermediate position IP that is 50% of the total length FL from the outflow end 32B. Third, the determination device 61 preferably makes a determination based on the measured value of the flow rate of flocs CF in a third portion R3 of the range R, in which flocs CF have been filtered to a certain extent or more. The first portion R1, the second portion R2, and the third portion R3 described in Sections 1 to 3 have a smaller amount of liquid components in the sludge than the portions of the range R other than the first portion R1, the second portion R2, and the third portion R3. Therefore, the liquid components and the turbulence on the surface of the flocs CF are smaller. As a result, it is possible to further reduce the influence on the determination, etc., of measurement errors in the flow velocity of the flocs CF caused by the liquid components and the turbulence on the surface of the flocs CF.

[0048] As shown in FIG. 2, the determination device 61 has a determination value calculation unit 611 that calculates a determination value based on the measurement value of the flow rate input from the rate measurement device 4, and a determination unit 612 that determines whether or not the flocs CF concentrated in the concentration device 3 are suitable for dewatering based on the determination value calculated by the determination value calculation unit 611.

[0049] The determination value calculation unit 611 calculates a determination value such as the average or maximum value of the multiple measurement values ​​input from the velocity measurement device 4. Therefore, even if there is a range in the measurement values ​​of the multiple flow rates input from the velocity measurement device 4 due to differences between individual flocs CF or the influence of measurement errors of the velocity measurement device 4, a determination value that is less affected by these factors can be used for the determination. Therefore, the determination can be made with high accuracy.

[0050] As shown in Figure 5, if the determination value calculated by the determination value calculation unit 611 is equal to or less than the concentration reference value, the determination unit 612 determines that the flocs CF concentrated in the concentrator 3 are suitable for dewatering. This determination is made because, when flocs CF suitable for dewatering are obtained from the concentrator 3, the flow rate of the flocs CF on the inclined screen 32 tends to be equal to or less than a certain value. The concentration reference value is set by testing the flow rate of the flocs CF flowing down the inclined screen 32 and the moisture content of the dewatered sludge when the flocs CF are dewatered, taking into account the test results. Note that, if the velocity measurement device 4 inputs a single measurement value of the flow rate to the determination device 61, the determination unit 612 determines whether the flocs CF concentrated in the concentrator 3 are suitable for dewatering based on the single input measurement value.

[0051] The determination of whether the flocs CF concentrated by the concentration device 3 are suitable for dewatering will be specifically explained with reference to FIG. 5. In FIG. 5, the horizontal axis represents the moisture content (%) of the dewatered sludge, and the vertical axis represents the flow rate (m / min) of the flocs CF flowing down the inclined screen 32. The graph in FIG. 5 shows the determination when the dewatered sludge is used as a combustion improver, as described above. When using dewatered sludge as a combustion improver, the moisture content standard for the dewatered sludge to determine whether the dewatered sludge has been sufficiently dewatered is 70%, and dewatered sludge with a moisture content of 70% or less is required. Hereinafter, the moisture content standard for the dewatered sludge to determine whether the dewatered sludge has been sufficiently dewatered will be referred to as the "dewatering standard value."

[0052] As can be seen from Figure 5, when the moisture content of the dewatered sludge is 70% or more, the flow velocity of the floc CF may be 4 m / min or more. Therefore, when the dewatered sludge is used as a combustion improver, the concentration standard value is set to 4 m / min. When the flow velocity of the floc CF is 4 m / min or less, the floc CF concentrated in the concentration device 3 is judged to be suitable for dewatering.

[0053] As shown in Fig. 2, the estimation device 62 receives as input the measured value of the flow velocity of flocs CF measured by the velocity measuring device 4. Similar to the determination device 61, the estimation device 62 estimates the water content of dewatered sludge based on the measured value of the flow velocity of flocs CF in at least a portion of a range R that is 90% or less from the outflow end 32B within the range from the inflow end 32A to the outflow end 32B. Here, similar to the determination device 61, it is preferable that the estimation device 62 performs estimation based on the measured values ​​of the flow velocity of flocs CF in a first portion R1, a second portion R2, and a third portion R3 within the range R. The reason for this is as explained for the determination device 61. By performing this estimation by the estimating device 62, the results of this estimation can be used to control the equipment that constitutes the dewatering treatment system 1.

[0054] The estimation device 62 has an estimation value calculation unit 621 that calculates an estimation value described below based on the measured value of the flow rate, and an estimation unit 622 that estimates the moisture content of the dewatered sludge based on the estimation value calculated by the estimation value calculation unit 621.

[0055] The estimation value calculation unit 621 calculates estimation values ​​such as the average value, minimum value, maximum value, difference between the minimum and maximum values, standard deviation, or a combination thereof, based on the measured values ​​of the plurality of flow rates. Therefore, even if there is a range in the measured values ​​of the plurality of flow rates due to differences between individual flocs CF or measurement errors of the velocity measuring device 4, an estimation value that is less affected by these factors can be used to estimate the moisture content of the dewatered sludge. This makes it possible to perform the estimation with high accuracy.

[0056] The estimation unit 622 estimates the moisture content of the dewatered sludge based on the estimation-use numerical value calculated by the estimation-use numerical value calculation unit 621. An example of estimation of the moisture content of the dewatered sludge will be described with reference to FIG.

[0057] As shown in Fig. 5, for example, when the moisture content of the dewatered sludge is in the range of 72% or more, the higher the moisture content of the dewatered sludge, the larger the maximum measured value of the flow rate. In other words, there is a correlation between the moisture content of the dewatered sludge and the maximum measured value of the flow rate, which is a type of estimation value. Therefore, the estimation unit 622 estimates the moisture content of the dewatered sludge corresponding to the maximum measured value of the flow rate calculated by the estimation value calculation unit 621 based on this correlation.

[0058] In the estimation of the dewatered sludge moisture content described with reference to FIG. 5 , the correlation between the dewatered sludge moisture content and the maximum measured value of the flow rate was focused on, and the maximum measured value of the flow rate was used as the estimation value. However, the estimation of the dewatered sludge moisture content described with reference to FIG. 5 is merely an example, and the estimation value used to estimate the dewatered sludge moisture content is not limited to the maximum measured value of the flow rate and can be changed as appropriate depending on the operating conditions and specifications of the dewatering system 1. For example, if there is a correlation between the dewatered sludge moisture content and the average, minimum, difference between the minimum and maximum calculated values ​​of multiple flow rates, or variations such as standard deviation, these may be used as the estimation value. Furthermore, although the above description has been given with reference to the measured value of the flow rate, when a single measured value of the flow rate is used, the estimation device 62 estimates the dewatered sludge moisture content based on that single measured value.

[0059] As shown in Fig. 2, the estimated value of the moisture content of the dewatered sludge estimated by the estimator 62 is input to the system controller 63. Based on the estimated value of the moisture content of the dewatered sludge estimated by the estimator 62, the system controller 63 controls the sludge supply pump 22, the coagulant supply pump 24, the dewatering device 5, or a combination thereof, so that the moisture content of the dewatered sludge is equal to or less than the dewatering standard. Therefore, the sludge supply pump 22, the coagulant supply pump 24, or the dewatering device 5 is controlled without the intervention of an operator. Therefore, the dewatering treatment system 1 can be controlled automatically.

[0060] The system control device 63 adjusts the flow rate of sludge delivered by the sludge supply pump 22 based on the estimated value of the moisture content of the dewatered sludge estimated by the estimator 62. For example, when the moisture content of the dewatered sludge estimated by the estimator 62 is greater than the dewatering reference value, the system control device 63 controls the sludge supply pump 22 to reduce the flow rate of sludge delivered by the sludge supply pump 22.

[0061] The system control device 63 adjusts the flow rate of the flocculant fed by the flocculant supply pump 24 based on the estimated value of the moisture content of the dewatered sludge estimated by the estimating device 62 .

[0062] The control performed by the system control device 63 on the coagulant supply pump 24 will be described with reference to Figure 6. In Figure 6, the horizontal axis shows the polymer injection rate (%), and the vertical axis shows the flow rate (m / min) of the coagulated flocs CF flowing down the inclined screen 32. The polymer injection rate indicates the proportion of the amount of coagulant supplied to a certain amount of sludge. The higher the polymer injection rate, the greater the amount of coagulant supplied to the sludge. In other words, the flow rate of coagulant delivered by the coagulant supply pump 24 is greater.

[0063] As can be seen from the graph in Figure 6, when the flow rate of the flocs CF is high, the polymer injection rate is low. On the other hand, when the flow rate of the flocs CF is low, the polymer injection rate is high. Therefore, when the flow rate of the flocs CF is high, the system control device 63 shown in Figure 2 controls the flocculant supply pump 24 to increase the flow rate of the flocculant sent out by the flocculant supply pump 24.

[0064] The system control device 63 controls the dewatering amount of the dewatering device 5 based on the estimated value of the moisture content of the dewatered sludge estimated by the estimating device 62. The dewatering amount is the amount of moisture that the dewatering device 5 dewaters from the flocculated flocs CF concentrated in the concentrating device 3. For example, in the case of a screw press dewatering machine having a screw, the dewatering amount is controlled by changing the rotation speed of the screw, etc. For example, when the moisture content of the dewatered sludge estimated by the estimating device 62 is higher than the dewatering reference value, the system control device 63 controls the dewatering device 5 to increase the dewatering amount of the dewatering device 5.

[0065] Preferably, the dewatering system 1 includes a cleaning device 71 that cleans the upper surface of the inclined screen 32 and a cleaning control device 72 that controls the cleaning device 71.

[0066] As the flocs CF are concentrated, the flocs CF gradually accumulate on the upper surface of the inclined screen 32. The cleaning device 71 is a device that washes away the flocs CF accumulated on the upper surface of the inclined screen 32 with water or the like. As the flocs CF accumulated on the upper surface of the inclined screen 32 are washed away by the cleaning device 71, the velocity measuring device 4 can measure the flow velocity of only the flocs CF flowing down the upper surface of the inclined screen 32. This improves the accuracy of the determination made by the determining device 61. Furthermore, it also improves the accuracy of the estimation made by the estimating device 62. This allows the system control device 63 to control each of the devices that make up the dewatering treatment system 1 appropriately to produce dewatered sludge whose sludge moisture content is equal to or lower than the dewatering standard.

[0067] The washing control device 72 receives an input of a measured value of the flow rate of the flocs CF from the velocity measuring device 4. If the input measured value of the flow rate is equal to or less than a cleaning reference value, the washing control device 72 controls the washing device 71 so that the washing device 71 washes the flocs CF deposited on the inclined screen 32. The cleaning reference value is a velocity that the velocity measuring device 4 is expected to output as a measured value of the velocity of the flocs CF deposited on the inclined screen 32 when the velocity measuring device 4 measures the velocity of the flocs CF deposited on the upper surface of the inclined screen 32.

[0068] The cleaning control device 72 controls the cleaning of the cleaning device 71, thereby cleaning the inclined screen 32 without the intervention of an operator. Therefore, the accuracy of the determination made by the determination device 61 and the accuracy of the estimation made by the estimation device 62 can be maintained at a level suitable for automatically controlling the dehydration treatment system 1 without the intervention of an operator.

[0069] Although the embodiments of the present invention have been described above, the forms to which the present invention can be applied are not limited to the above-mentioned embodiments, and appropriate modifications can be made without departing from the gist of the present invention, which is to determine whether or not the flocs CF concentrated in the concentration device 3 are suitable for dewatering based on the flow rate of the flocs CF in the concentration step.

[0070] Similarly, the forms to which the present invention can be applied are not limited to the above-described embodiments, and appropriate modifications can be made within the scope of the invention, which is to estimate the water content of dewatered sludge based on the flow rate of the flocculated flocs CF in the concentration step and use the estimated result to control the equipment that constitutes the dewatering treatment system 1. [Explanation of symbols]

[0071] 1. Dehydration treatment system 3 Concentrator 4 Speed ​​measuring device 5 Dehydration equipment 22 Sludge supply pump 23 Coagulation tank 24 Coagulant supply pump 32 tilt screen 32A Inlet end 32B Outflow end 41 Camera 42 Speed ​​calculator 61 Judgment device 62 Estimation device 63 System Control Device 71 Cleaning equipment 72 Cleaning control device CF Coagulated floc

Claims

1. A dehydration treatment system that thickens and dehydrates sludge, a coagulation tank into which the sludge and a coagulant for coagulating the sludge are supplied to produce coagulated flocs of the sludge; a concentrating device that allows the flocs to flow down and concentrates the flocs; a velocity measuring device that measures the flow velocity of the flocs flowing down the thickening device; a determining device that determines that the concentrated flocs are suitable for dewatering if the flow rate is equal to or less than a concentration reference value, which is a reference value for determining whether the flocs concentrated in the concentrator are suitable for dewatering; a dewatering device for dewatering the concentrated flocs; Equipped with The speed measuring device is at least one image capture device for capturing images of the flocs flowing down the thickening device; a velocity calculator that calculates a flow velocity of the flocs flowing down the concentration device based on a first image captured by the image capture device at a first time and a second image captured by the image capture device at a second time; and The speed calculator a position definition unit that defines a first position of the flocs at the first time based on the first image and defines a second position of the flocs at the second time based on the second image; a distance calculation unit that calculates a distance from the first position to the second position; a time calculation unit that calculates an elapsed time from the first time to the second time; a velocity calculation unit that calculates a flow velocity of the flocs flowing down the concentration device based on the distance from the first position to the second position and the elapsed time from the first time to the second time; and and The concentrating device comprises: an inclined screen for concentrating the flocs by filtration while allowing them to flow downward; The tilt screen is an inlet portion into which the flocs flow; an outflow portion through which the flocs flow out, The inclined screen is inclined so that the outlet portion is located lower than the inlet portion, The determination device determines whether the concentrated flocs are suitable for dewatering based on the flow rate of the flocs in at least a portion of a region from the inlet to the outlet that is 90% or less from the outlet.

2. The position definition unit defining a first point cloud consisting of a plurality of points on a boundary between the floc and a boundary other than the floc in the first image, and defining the position of the first point cloud as the first position; 2. The dewatering treatment system according to claim 1, wherein a second point cloud consisting of a plurality of points is set in the second image along a downstream flow direction of the flocs and on a boundary between the flocs and a portion other than the flocs, the second point cloud being located downstream of each of the points constituting the first point cloud, thereby defining the position of the second point cloud as the second position.

3. the velocity calculator calculates the flow velocity of one floc at a plurality of times, the flow velocity of a plurality of flocs, or the flow velocity of the one floc at a plurality of times and the flow velocity of a plurality of flocs, based on a plurality of images taken at different times by the imaging device; The determination device a determination value calculation unit that calculates an average or maximum value of the plurality of flow velocities calculated by the velocity calculator; a determination unit that determines that the concentrated flocs are suitable for dewatering if the average or maximum value of the plurality of flow rates calculated by the determination value calculation unit is equal to or less than the concentration reference value; The dehydration treatment system according to claim 1 or 2, comprising:

4. an estimation device that estimates a dewatered sludge moisture content, which is the amount of moisture contained in dewatered sludge obtained by dewatering the concentrated flocs, based on the flow rate of the flocs in at least a part of a portion that is 90% or less from the outflow portion within the range from the inflow portion to the outflow portion; a system control device that controls devices constituting the dehydration treatment system; Furthermore, A dewatering treatment system as described in any one of claims 1 to 3, wherein the system control device controls the equipment so that the dewatered sludge moisture content is below a dewatering standard value, which is a standard value for determining whether the dewatered sludge has been sufficiently dewatered, based on the dewatered sludge moisture content estimated by the estimation device.

5. a sludge supply pump for supplying the sludge to the coagulation tank; The dewatering treatment system described in claim 4, wherein the system control device controls the flow rate of the sludge supplied by the sludge supply pump to the coagulation tank based on the dewatered sludge moisture content estimated by the estimating device so that the dewatered sludge moisture content is below the dewatering standard value.

6. a flocculant supply pump that supplies the flocculant to the flocculation tank; The dewatering treatment system described in claim 4 or claim 5, wherein the system control device controls the flow rate of the coagulant supplied to the coagulation tank by the coagulant supply pump based on the dewatered sludge moisture content estimated by the estimating device so that the dewatered sludge moisture content is below the dewatering standard value.

7. A dehydration treatment system as described in any one of claims 4 to 6, wherein the system control device controls the dehydration amount of the dehydration device based on the dehydrated sludge moisture content estimated by the estimation device so that the dehydrated sludge moisture content is below the dehydration standard value.

8. a washing device for washing the flocs deposited in the thickening device; a cleaning control device that controls the cleaning device; Furthermore, 8. The dewatering treatment system according to claim 1, wherein the cleaning control device controls the cleaning device so that the cleaning device cleans the flocs deposited in the concentration device when the flow rate of the flocs measured by the velocity measuring device is equal to or lower than a cleaning reference value that is a reference value for cleaning the flocs in the cleaning device.

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