JP7813596B2 - Dehydration Treatment System - Google Patents

Description

The present invention relates to a dehydration treatment system that concentrates and dehydrates sludge.

Sludge generated from sewage treatment facilities or septic tanks is dehydrated for use as a fuel additive in incineration equipment within the facility or in other waste treatment facilities. 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.

Japanese Patent Application Laid-Open No. 2020-146614 Patent No. 4238983

In dehydration systems that dehydrate sludge, a determination is made before the dehydration process as to whether the concentrated sludge is suitable for dehydration. The results of this determination are then used to control the equipment that makes up the dehydration system. However, because the determination of whether the concentrated sludge is suitable for dehydration requires a visual inspection by a dehydration system operator, there has been a problem in that it is difficult to automate the control of the dehydration system.

The inventions disclosed in Patent Documents 1 and 2 measure the size of concentrated sludge and, based on the measurement results, determine whether the concentrated sludge is suitable for dewatering. However, determining whether a sludge is suitable for dewatering based on its size complicates the overall process for making such determinations due to factors such as the shape of the sludge changing during the concentration process and the complexity of the process for calculating the size of the concentrated sludge, and this still means that automating a dewatering treatment system remains difficult.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a dehydration treatment system that concentrates and dehydrates sludge, in which overall control can be automated by automatically determining, through a simple process, whether the sludge before dehydration is suitable for dehydration.

According to one aspect of the present invention, a dewatering treatment system is a dewatering treatment system that concentrates and dewaters sludge, and is primarily characterized by comprising: a coagulation tank that is supplied with the sludge and a coagulant that coagulates the sludge to produce coagulated flocs; a concentrator that causes the coagulated flocs to flow downward and concentrate the coagulated flocs; a speed measuring device that measures the flow rate of the coagulated flocs flowing downward through the concentrator; 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 whether the concentrated coagulated flocs are suitable for dewatering; and a dewatering device that dewaters the concentrated coagulated flocs.

The dehydration treatment system of the present invention can automatically determine whether pre-dehydration sludge is suitable for dehydration through a simple process, thereby automating the control of the dehydration treatment system.

1 is a diagram showing an outline of a dehydration treatment system according to an embodiment. FIG. 2 is a diagram showing details of a concentrating device of the dehydration treatment system according to the embodiment. FIG. 2 is a diagram showing a first image captured by an imaging device in the embodiment. FIG. 10 is a diagram showing a second image captured by the imaging device in the embodiment. 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. 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. 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.

Embodiments will be described below with reference to the drawings. Note that the same or equivalent parts shown in the drawings will be designated by the same reference symbols. Descriptions of parts designated by the same reference symbols will not be repeated.

An overview of the dehydration system 1 of this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing an overview of the dehydration system 1 of this embodiment. Figure 2 is a diagram showing details of the concentrator 3 of the dehydration system 1 of this embodiment.

Sludge is supplied to the dehydration treatment system 1 shown in Figure 1. The dehydration treatment system 1 performs a dehydration treatment on the supplied sludge.

First, the dewatering process involves a flocculation process in which the sludge supplied to the dewatering system 1 is flocculated. The sludge flocculated in the flocculation process is referred to as "flocculated flocs CF." Second, the dewatering process involves a concentration process in which the flocculated flocs CF are concentrated. In the concentration process, the flocculated flocs CF flow down a concentration screen, where they are separated from the filtrate and concentrated. Finally, the dewatering process involves a dewatering process in which the concentrated flocculated flocs CF are dewatered. The flocculated flocs CF dewatered in the dewatering process are referred to as "dewatered sludge."

Dewatered sludge is used, for example, as a combustion improver in incineration facilities or waste disposal facilities. Therefore, the "dewatered sludge moisture content," which is the amount of water contained in the dewatered sludge, must be below a standard established for each application. Specifically, when used as a combustion improver in incineration facilities or waste disposal facilities, the standard for dewatered sludge moisture content is 70%. The dewatered sludge moisture content will be below the standard if the flocs CF concentrated in the concentration process are suitable for dewatering. Therefore, by determining whether the flocs CF concentrated in the concentration process are suitable for dewatering, the determination result can be used to determine whether the dewatered sludge moisture content will be below the standard. Furthermore, by controlling the equipment that makes up the dewatering treatment system 1 based on the state of the flocs CF concentrated in the concentration process, flocs CF in a state suitable for dewatering can be produced by concentrating them.

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 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 coagulant to the coagulation tank 23, a thickener 3 that thickens the 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, sludge supply pump 22, coagulation tank 23, and coagulant supply pump 24 perform the coagulation process. The thickener 3 performs the concentration process. The dewatering device 5 performs the dewatering process.

The mixing tank 21 has a mixing tank 211 to which sludge and dewatering aid are supplied, and a mixing agitator 212 that agitates the sludge and dewatering aid supplied to the mixing tank 211. The sludge and dewatering aid are mixed by being agitated by the mixing agitator 212. Sludge mixed with a dewatering aid is more likely to flocculate than sludge not mixed with a dewatering aid. Examples of dewatering aids include fibrous materials, inorganic flocculants, pH adjusters, and wood flour.

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. This allows the sludge to be supplied to the coagulation tank 23.

Sludge is supplied to the coagulation tank 23 from the mixing tank 21 via the sludge supply pump 22. A coagulant is also supplied to the coagulation tank 23 from the 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 used as the coagulant includes organic polymers and inorganic polymers.

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

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

The thickener inlet pipe 31 is a pipe with both ends opening horizontally. 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 connected. The other end of the thickener inlet pipe 31 is connected to the inclined screen 32.

As described above, the flocculated flocs CF produced 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 in the flocculation tank 231 rises. When the liquid level of the sludge in the flocculation tank 231 rises to the position of the thickener inlet pipe 31, the liquid components of the sludge and the flocculated flocs CF flow into the thickener inlet pipe 31. After flowing into the thickener inlet pipe 31, the liquid components of the sludge and the flocculated flocs CF flow toward the inclined screen 32.

The inclined screen 32 has an inlet section into which the flocs CF flow and an outlet section from which the flocs CF that 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.

The liquid components of the sludge and flocs CF that flow 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 aforementioned 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 flocs CF that flow toward the inclined screen 32 flow into it.

The inclined screen 32 is a screen that filters the liquid components of the sludge and flocs CF as they flow downward. After flowing into the inlet end 32A, the liquid components of the sludge and flocs CF flow onto the upper surface of the inclined screen 32. The liquid components of the sludge and flocs CF that flow 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 side of the inclined screen 32. The liquid components of the sludge that pass through the inclined screen 32 are called "concentrated filtrate."

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

The concentrator outlet pipe 33 is a pipe with vertical openings at both ends. The concentrator outlet pipe 33 is positioned so that flocculated flocs CF flowing out from the outlet end 32B flow into the inside of the concentrator outlet pipe 33 through openings provided at the upper end of the concentrator outlet pipe 33. The upper end of the concentrator outlet pipe 33 is connected to the outlet end 32B of the inclined screen 32. The lower end of the concentrator outlet pipe 33 is connected to the dewatering device 5. The concentrator outlet pipe 33 does not need to be connected to the outlet end 32B as long as the flocculated flocs CF flowing out from the outlet end 32B flow into the inside of the concentrator outlet pipe 33. In addition, although the inlet end 32A has been described as the inlet portion in the embodiment, the inlet portion is not limited to the inlet end 32A as long as it is a portion into which flocculated flocs CF flow. Similarly, the outlet portion is not limited to the outlet end 32B as long as it is a portion into which flocculated flocs CF flow.

The flocs CF heading toward the thickener outlet pipe 33 flow into the inside of the thickener outlet pipe 33. The flocs CF that have flowed into the inside of the thickener outlet pipe 33 flow into the dehydrator 5.

The dewatering device 5 dewaters the flocculated flocs CF concentrated in the concentration device 3, separating the "dewatered filtrate," which is the liquid component of the concentrated flocculated flocs CF, from dewatered sludge, producing dewatered sludge. The dewatering device 5 is, for example, a screw press dewatering machine.

2 to 6, a detailed description will be given of the determination of whether the flocs CF concentrated in the concentrator 3 in the dewatering system 1 according to the embodiment are suitable for dewatering, and the control of each component of the dewatering system 1 based on the state of the flocs CF concentrated in the concentrator 3. FIG. 3A shows a first image M1 captured by the image capture device 41 according to the embodiment. FIG. 3B shows a second image M2 captured by the image capture device 41 according to the embodiment. FIG. 4 shows 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 in the dewatering device 5 and the flow velocity of the flocs CF flowing down 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 velocity of the flocs CF flowing down the concentrator 3 according to the embodiment.

As shown in FIG. 2, the dewatering treatment system 1 further includes a velocity measuring device 4 that measures the flow velocity of the flocs CF flowing down the concentrator 3, a determining device 61 that determines whether the flocs CF concentrated in the concentrator 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 treatment system 1 based on the estimation results of the estimating device 62.

The velocity measuring device 4 has at least one camera 41 positioned so as to capture an image of the top surface of the inclined screen 32, and a velocity calculator 42 to which the image captured by the camera 41 is input. The velocity measuring device 4 calculates the flow velocity of the flocs CF flowing down the top surface of the inclined screen 32 from the image captured by the camera 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 makes up the dewatering treatment system 1.

The imaging device 41 captures images of the flocs CF flowing down the top surface of the inclined screen 32. The imaging device 41 is, for example, a camera that records images such as video or photographs.

As shown in Figures 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, the image captured by the imaging device 41 at the first time will be referred to as the first image M1, the image captured by the imaging device 41 at the second time will be referred to as the second image M2, and the image captured by the imaging device 41 at the Nth time (N is an integer greater than or equal to 3) will be referred to as the Nth image.

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: the first image M1 ( FIG. 3A ) captured by the image capture device 41 at the first time, the second image M2 ( FIG. 3B ) captured by the image capture device 41 at the second time, and the Nth image captured by the image capture device 41 at the Nth time. The velocity calculator 42 is a terminal having a processor such as an MPU (Micro Processing Unit) and a CPU (Central Processing Unit), and memory 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, estimation device 62, system control device 63, and cleaning control device 72, which will be described later.

The velocity calculator 42 has a position definition unit 421 that defines the position 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 position of the flocs CF defined by the position definition unit 421; a time calculation unit 423 that calculates the time elapsed as the flocs CF flow downward based on the image capture time recorded in the Nth image input from the camera 41; and a velocity calculation unit 424 that calculates the velocity of the flocs CF flowing downward based on the distance traveled by the flocs CF calculated by the distance calculation unit 422 and the time elapsed as the flocs CF flow downward calculated by the time calculation unit 423.

The 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 Figure 3A and the second image M2 shown in Figure 3B. Hereinafter, for ease of explanation, the downward direction in Figures 3A and 3B will be referred to as the downstream direction. The direction opposite 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 Figures 3A and 3B, flocs CF flow downward from the upstream direction to the downstream direction. Furthermore, any position in the first image M1 and the second image M2 is expressed using a Cartesian coordinate system in the upstream-downstream direction and the left-right direction. Specifically, if an arbitrary point P11 is defined in the first image M1, the left-right position of P11 will be expressed as X1, and the upstream-downstream position of P11 will be expressed as Y11. Coordinates expressed with the same character indicate the same position in each direction.

As shown in FIG. 3A, the position definition unit 421 defines a first position of the agglomerated flocs CF at a first time based on the first image M1. The first position is defined by setting a first point cloud consisting of multiple points on the boundary between the agglomerated flocs CF and areas other than the agglomerated flocs 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 position of this first point cloud is defined as the first position.

The position definition unit 421 defines the 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 multiple 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.

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

The distance calculation unit 422 shown in FIG. 2 calculates the distance from the first position to the second position based on the first position and second position defined by the position definition unit 421. The distance from the first position to the second position is calculated by determining the distance from each of the points constituting the first point cloud to each of the points in the second point cloud that correspond to each of the points constituting the first point cloud.

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.

The velocity calculation unit 424 calculates the flow 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 velocity of the flocs CF calculated by the velocity calculation unit 424 is output to the determination unit 61 and the estimation unit 62 as a measurement value measured by the velocity measurement device 4.

The velocity calculator 42 calculates the flow velocity of one floc CF at multiple times, the flow velocity of multiple flocs CF, or the flow velocity of one floc CF at multiple times and the flow velocity of multiple flocs CF, based on multiple images captured by the image capture device 41 at different times. Therefore, the velocity calculator 42 calculates multiple flow velocities. This provides multiple pieces of information on the flow velocity 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.

The determination device 61 receives as input the measured value of the flow velocity of the flocs CF measured by the velocity measurement device 4. If the determination value, described below, calculated based on the measured value of the flow velocity, is equal to or less than the concentration reference value, the determination device 61 determines that the flocs CF concentrated in the concentrator 3 are suitable for dewatering. Here, the concentration reference value is a reference value for determining whether the flocs CF concentrated in the concentrator 3 are suitable for dewatering. The determination device 61 performs the simple process of comparing the determination value with the concentration reference value, eliminating the need for an operator to make this determination. Therefore, this determination is performed automatically through simple processing.

The determination device 61 determines whether the concentrated flocs CF are suitable for dewatering based on the measured 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 , 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%, range R is the portion from the outlet end 32B to the range reference position RP, which is 90% of the total length FL. In range R, the liquid components of the sludge and the surfaces of the flocs CF are less disturbed and more stable. As a result, the impact of measurement errors in the flow velocity of the flocs CF due to the liquid components of the sludge and surface disturbances of the flocs CF on the determination can be reduced.

Furthermore, the determination device 61 shown in FIG. 2 preferably makes a determination based on the measured value of the flow velocity 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 velocity 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 velocity of flocs CF in a second portion R2 of the range R that is as wide as possible, excluding 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 velocity 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, second portion R2, and third portion R3 described in sections 1 to 3 have a smaller amount of liquid component in the sludge than the remaining portions of range R other than the first portion R1, second portion R2, and third portion R3. Therefore, the liquid component and surface turbulence of the flocs CF are reduced. As a result, the impact on determinations, etc., of measurement errors in the flow velocity of the flocs CF caused by the liquid component and surface turbulence of the flocs CF can be further reduced.

As shown in FIG. 2, the determination device 61 has a determination value calculation unit 611 that calculates a determination value based on the measured flow rate input from the velocity measurement device 4, and a determination unit 612 that determines whether 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.

The determination value calculation unit 611 calculates a determination value, such as the average or maximum value, for 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 velocities input from the velocity measurement device 4 due to differences between individual flocs CF or measurement errors in the velocity measurement device 4, a determination value that is less affected by these factors can be used for the determination. This allows the determination to be made with high accuracy.

As shown in FIG. 5, the determination unit 612 determines that the flocs CF concentrated in the concentrator 3 are suitable for dewatering if the determination value calculated by the determination value calculation unit 611 is equal to or less than the concentration reference value. 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 below a certain level. 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, when 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.

The determination of whether the flocs CF concentrated in the concentration device 3 are suitable for dewatering will be explained in detail with reference to Figure 5. In Figure 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 Figure 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."

Figure 5 shows that when the moisture content of dewatered sludge is 70% or higher, the flow velocity of the flocs CF may be 4 m/min or higher. Therefore, when using dewatered sludge as a combustion improver, the concentration standard value is set to 4 m/min. When the flow velocity of the flocs CF is 4 m/min or lower, the flocs CF concentrated in the concentration device 3 are judged to be suitable for dewatering.

As shown in FIG. 2, the estimation device 62 receives the measured value of the flow velocity of the flocs CF measured by the velocity measurement device 4. Like the determination device 61, the estimation device 62 estimates the water content of the dewatered sludge 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. Here, as with the determination device 61, it is preferable that the estimation device 62 performs its estimation based on the measured value of the flow velocity of the flocs CF in the first portion R1, the second portion R2, and the third portion R3 of the range R. The reason for this is as explained for the determination device 61. By performing this estimation by the estimation device 62, the results of this estimation can be used to control the equipment that makes up the dewatering treatment system 1.

The estimation device 62 has an estimation value calculation unit 621 that calculates an estimation value (described below) based on the measured 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.

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 of these, based on the measured values of multiple flow rates. Therefore, even if there is a range in the measured values of multiple flow rates due to differences between individual flocs (CF) or measurement errors in the velocity measurement 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 allows for accurate estimation.

The estimation unit 622 estimates the moisture content of the dewatered sludge based on the estimation values calculated by the estimation value calculation unit 621. An example of estimating the moisture content of the dewatered sludge is described with reference to Figure 5.

As shown in Figure 5, for example, when the moisture content of the dewatered sludge is in the range of 72% or higher, 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.

Note that in the estimation of the dewatered sludge moisture content described with reference to Figure 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 Figure 5 is only one 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 usage conditions and specifications of the dewatering treatment system 1. For example, if there is a correlation between the dewatered sludge moisture content and the average value, minimum value, difference between the minimum and maximum values of multiple calculated flow rates, or variations such as standard deviation, these may be used as estimation values. Also, while the above describes the case where the flow rate is measured, if there is a single measured value of the flow rate, the estimation device 62 estimates the dewatered sludge moisture content based on that single measured value.

As shown in FIG. 2, the system control device 63 receives an estimated value of the dewatered sludge moisture content estimated by the estimator 62. Based on the estimated value of the dewatered sludge moisture content estimated by the estimator 62, the system control device 63 controls the sludge supply pump 22, the flocculant supply pump 24, the dewatering device 5, or a combination thereof, so that the dewatered sludge moisture content is below the dewatering standard. Therefore, the sludge supply pump 22, the flocculant supply pump 24, or the dewatering device 5 is controlled without operator intervention. Therefore, the dewatering treatment system 1 can be controlled automatically.

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, if 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.

The system control device 63 adjusts the flow rate of the flocculant sent by the flocculant supply pump 24 based on the estimated value of the dewatered sludge moisture content estimated by the estimator 62.

Referring to Figure 6, the control performed by the system control device 63 on the coagulant supply pump 24 will be explained. 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.

From the graph in Figure 6, it can be seen that 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 delivered by the flocculant supply pump 24.

The system control device 63 controls the dewatering amount of the dewatering device 5 based on the estimated value of the dewatered sludge moisture content 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 with a screw, the dewatering amount is controlled by changing the screw rotation speed, etc. For example, if the dewatered sludge moisture content estimated by the estimating device 62 is greater than the dewatering reference value, the system control device 63 controls the dewatering device 5 to increase the dewatering amount.

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.

By concentrating the flocs CF, 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. As a result, the system control device 63 can appropriately control each of the devices that make up the dewatering treatment system 1 to produce dewatered sludge whose sludge moisture content is below the dewatering standard.

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

The cleaning control device 72 controls the cleaning of the cleaning device 71, so that the inclined screen 32 is cleaned 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.

The above describes an embodiment of the present invention, but the forms to which the present invention can be applied are not limited to the above embodiment, and appropriate modifications can be made without departing from the spirit of the present invention, which is to determine whether 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 process.

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 without departing from the spirit of the present invention, which is to estimate the moisture content of dewatered sludge based on the flow rate of the flocculated flocs CF in the concentration process and use the estimated results to control the equipment that makes up the dewatering treatment system 1.

REFERENCE SIGNS LIST 1 Dewatering treatment system 3 Thickener 4 Speed measurement device 5 Dewatering device 22 Sludge supply pump 23 Coagulation tank 24 Coagulant supply pump 32 Inclined screen 32A Inlet end 32B Outlet end 41 Camera 42 Speed calculator 61 Determination device 62 Estimation device 63 System control device 71 Cleaning device 72 Cleaning control device CF Coagulated floc

Claims (8)

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 concentrated flocs are suitable for dewatering in the flocs concentrated by the concentrator;
a dewatering device for dewatering the concentrated flocs ,
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 . 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. 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 determining unit that determines that the concentrated flocs are suitable for dewatering if an average value or a maximum value of the plurality of flow rates calculated by the determination value calculating unit is equal to or less than the concentration reference value. 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;
and a system control device that controls the devices that constitute the dehydration treatment system.
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 . 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. 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. 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. a washing device for washing the flocs deposited in the thickening device;
a cleaning control device that controls the cleaning device,
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.