Information processing device, dewatering machine, control device, method for determining sudden decrease in flow rate, and program for determining sudden decrease in flow rate

Abstract

To appropriately detect a sudden decrease in the flow rate of liquid supplied to the dewatering machine. [Solution] The information processing device (1) includes a setting unit (12) that sets a reference value for the flow rate of the liquid supplied to the dewatering machine (9), and a determination unit (13) that determines that the flow rate has decreased sharply if the flow rate remains below a predetermined ratio of less than 1 for a predetermined period of time. The setting unit sets the flow rate as a new reference value each time the flow rate increases during a period in which the flow rate increases in a time series, and maintains the reference value set at the start of the period during a period in which the flow rate decreases in a time series.

Description

Technical Field

[0001] The present invention relates to an information processing device for determining the flow rate of a liquid containing suspended solids, a dehydrator including the information processing device, and a control device that performs control according to a determination result by the information processing device. Further, the present invention also relates to a flow rate sudden decrease determination method executed by the information processing device and a flow rate sudden decrease determination program.

Background Art

[0002] Patent Document 1 discloses an information processing device that appropriately adjusts the mode of adding a chemical to a liquid containing suspended solids. The information processing device includes a moisture content prediction unit that calculates a first predicted value using first measurement data and a second predicted value using second measurement data for the moisture content of the dehydrated cake. Here, the first measurement data is measurement data related to the properties of the liquid before the mode of adding the chemical is changed. Also, the second measurement data is measurement data related to the properties of the liquid after the mode of adding the chemical is changed. Further, the information processing device includes an adjustment unit that adjusts the mode of adding the chemical based on the first predicted value and the second predicted value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The sludge flow rate supplied to the dewatering machine fluctuates constantly, and especially under control that keeps the sludge input pressure constant, it decreases sharply when the coagulation state deteriorates. If the dewatering machine continues to operate under the same operating conditions as before the sharp decrease in sludge flow rate, the operating efficiency will decrease. Therefore, when the sludge flow rate suddenly decreases, it is necessary to take measures such as reviewing the coagulant injection rate to improve it as soon as possible. For this reason, it is desirable to detect the occurrence of a sharp decrease in sludge flow rate as quickly and accurately as possible. However, since both the sludge flow rate and the rate of decrease in sludge flow rate vary considerably depending on the situation, it is difficult to perform rule-based detection of a sharp decrease in sludge flow rate at a level equivalent to visual confirmation by workers.

[0005] One aspect of the present invention aims to appropriately determine a sudden decrease in the flow rate of liquid supplied to a dewatering machine. [Means for solving the problem]

[0006] To solve the above problems, an information processing device according to one aspect of the present invention includes a flow rate acquisition unit that acquires the flow rate of a liquid supplied to a dewatering machine that dewaters a liquid discharged from a flocculation tank to which a chemical agent for flocculating the suspended solids is added; a setting unit that sets a reference value for the flow rate; and a determination unit that determines that the flow rate has decreased sharply if the ratio of the flow rate to the reference value remains below a predetermined ratio of less than 1 for a predetermined period of time. The setting unit sets the flow rate as a new reference value each time the flow rate increases during a period in which the flow rate increases in a time series, and maintains the reference value set at the start of the period during a period in which the flow rate decreases in a time series.

[0007] Furthermore, a method for determining a sudden decrease in flow rate according to one aspect of the present invention is a method for determining a sudden decrease in flow rate that is performed by one or more information processing devices, and includes: a flow rate acquisition step of acquiring the flow rate of a liquid supplied to a dewatering machine that dewaters the liquid while transporting the liquid discharged from a flocculation tank to which a chemical agent for flocculating the suspended solids is added to a liquid containing suspended solids; a setting step of setting a reference value for determining a sudden decrease in the flow rate; and a determination step of determining that the flow rate has suddenly decreased if the ratio of the flow rate to the reference value is less than a predetermined ratio of less than 1 for a predetermined period of time, wherein the setting step sets the flow rate as the reference value each time the flow rate increases during a period in which the flow rate increases in a time series, and maintains the reference value set at the start of the period during a period in which the flow rate decreases in a time series.

[0008] Each aspect of the present invention may be implemented by a computer. In this case, the program for the information processing device that enables the computer to implement the information processing device and control device by operating the computer as each part (software element) of the information processing device and control device, and the computer-readable recording medium on which the program is recorded, also fall within the scope of the present invention. [Effects of the Invention]

[0009] According to one aspect of the present invention, a sudden decrease in the flow rate of the liquid supplied to the dewatering machine can be appropriately determined. [Brief explanation of the drawing]

[0010] [Figure 1] This block diagram shows an example configuration of a control system including an information processing device and a control device according to an embodiment. [Figure 2] This is a block diagram showing an example of the configuration of the main parts of an information processing device according to an embodiment. [Figure 3] This graph shows examples of flow rates and reference values. [Figure 4] This is a block diagram showing an example of the configuration of the main parts of the control device according to the embodiment. [Figure 5] This graph shows an example of the time-series changes in the chemical injection rate and sludge flow rate when the control device does not have a delay timer and the flow rate decreases sharply at a certain point in the chemical injection rate. [Figure 6] This graph shows an example of the time-series changes in the chemical injection rate and sludge flow rate when a delay timer is installed in the control device and the flow rate decreases sharply at a certain point in the chemical injection rate. [Figure 7] This graph shows a different example from Figure 6 of the time-series changes in the chemical injection rate and sludge flow rate when a delay timer is provided in the control device and the flow rate decreases sharply at a certain point in the chemical injection rate. [Figure 8] This graph shows an example of the time-series changes in the chemical injection rate and sludge flow rate when a delay timer is installed in the control device and the flow rate decreases sharply during the chemical injection rate control period. [Figure 9] This graph shows a different example from Figure 8 of the time-series changes in the chemical injection rate and sludge flow rate when a delay timer is provided in the control device and the flow rate decreases sharply during the chemical injection rate control period. [Figure 10] This graph shows a different example from Figures 8 and 9 of the time-series changes in the chemical injection rate and sludge flow rate when a delay timer is provided in the control device and the flow rate decreases sharply during the chemical injection rate control period. [Figure 11] This is a flowchart illustrating an example of processing in an information processing device. [Figure 12] This flowchart shows an example of processing in a control device. [Figure 13] Figure 12 is a flowchart showing an example of the content of the rapid decline response control. [Figure 14] Figure 13 is a flowchart illustrating an example of the contents of the first adjustment process. [Figure 15] Figure 13 is a flowchart illustrating an example of the contents of the second adjustment process. [Modes for carrying out the invention]

[0011] 〔System Configuration〕 Based on FIG. 1, the configuration of a control system according to an embodiment of the present invention will be described. FIG. 1 is a diagram showing a configuration example of the control system 100. The control system 100 is a system used in a plant that adds a chemical for aggregating suspended solids to the liquid to be treated (liquid) in the flocculation tank to form flocs, and performs solid-liquid separation of the liquid to be treated in which the flocs are formed. Hereinafter, an example in which the liquid to be treated is sludge will be described, but the control system 100 is also applicable to plants that treat liquids to be treated other than sludge. Note that sludge is a liquid containing fine solids generated in wastewater treatment or the like, and can also be called slurry.

[0012] Although details will be described below, the control system 100 performs each treatment from the step of aggregating the suspended solids in the sludge to be treated to form flocs to make the sludge to be treated into aggregated sludge, to the step of dehydrating the aggregated sludge to obtain dehydrated sludge (also called dehydrated cake) and dehydrated filtrate, among the sludge treatment steps. As shown in FIG. 1, the control system 100 includes an information processing device 1, a control device 3, a flocculator 5, and a dehydrator 9.

[0013] The flocculator 5 is a device that forms flocs by adding a chemical for aggregating suspended solids to the liquid to be treated in the flocculation tank and stirring it appropriately. Specifically, the flocculator 5 uses sludge as the liquid to be treated, aggregates the suspended solids in the sludge to form flocs, and generates aggregated sludge. The flocculator 5 in FIG. 1 includes a flocculation tank 51, a stirring blade 52, a motor 53, and an inspection window 54. In addition, the flocculator 5 is provided with a sludge inlet 55, a chemical inlet 56, and an outlet 57.

[0014] Furthermore, a photographing device 72 and a lighting device 71 for photographing are attached to the inspection window 54. The photographing device 72 may be any device that can at least take a still image. During the operation of the control system 100, it is preferable that the flocculation tank 51 is made of a material that is not light-transmissive so that the way light hits the flocs does not change. Also, as shown in the illustrated example, the photographing device 72 and the lighting device 71 are preferably housed in a light-shielding dark box with an opening on the inspection window 54 side.

[0015] The dehydrator 9 is a device that separates the solid and liquid components of the treated liquid in which flocs are formed. Specifically, the dehydrator 9 is disposed downstream of the flocculator 5 and dehydrates while transporting the treated liquid containing the flocculated sludge discharged from the flocculator 5. The dehydrator 9 in FIG. 1 is a screw press type dehydrator including an outer cylinder screen 91 and a screw 92. The dehydrator 9 is also provided with a sludge inlet 93, a filtrate outlet 94, and a dehydrated cake outlet 95. Although not shown in the figure, the dehydrator 9 also includes a motor or the like for rotationally driving the screw 92. Of course, the dehydrator 9 may be any device that can dehydrate the flocculated sludge and is not limited to the screw press type. For example, a centrifugal dehydrator, a filter press type dehydrator, or a belt press dehydrator may also be applied.

[0016] In the control system 100, the sludge to be treated is continuously or intermittently supplied from the sludge inlet 55 into the flocculation tank 51 of the flocculator 5 by a supply device (not shown), and the sludge pushed out and discharged from the flocculation tank 51 is supplied to the dehydrator 9. Therefore, the flow rate of the sludge supplied to the flocculation tank 51 and the flow rate of the sludge supplied to the dehydrator 9 coincide at the same time. The supply speed of the sludge may be automatically controlled by the supply device or its control device 3 according to the treatment speed of the sludge by the flocculator 5 and the dehydrator 9.

[0017] ]Then, a chemical agent (at least containing a coagulant) is introduced into the sludge in the coagulation tank 51 through the chemical inlet 56 to coagulate the sludge. In this state, the motor 53 is driven to rotate the stirring blade 52, stirring the sludge and chemical agent to form flocs. The coagulated sludge, which is a mixture of the formed flocs and the water contained in the sludge, is discharged from the discharge port 57.

[0018] Next, the coagulated sludge is supplied into the outer shell screen 91 from the sludge inlet 93 of the dewatering machine 9. Inside the dewatering machine 9, the coagulated sludge is dewatered under pressure from the screw 92, the filtrate is discharged from the filtrate outlet 94, and the dewatered cake, which is a mass of dewatered coagulated sludge, is discharged from the dewatered cake outlet 95.

[0019] [Configuration of the information processing device] Figure 2 is a block diagram showing an example of the configuration of the main parts of the information processing device 1. As shown in Figure 2, the information processing device 1 comprises a control unit 10 and a storage unit 20. The information processing device 1 may also further include a communication unit (not shown) for communicating with other devices. These other devices may be devices that constitute the control system 100, or devices outside the control system 100.

[0020] The control unit 10 determines whether the flow rate of the liquid containing suspended solids supplied from the coagulation tank 51 to the dewatering machine 9 has decreased sharply. In the following description, the liquid supplied from the coagulation tank 51 to the dewatering machine 9 may be simply referred to as "liquid." Similarly, the flow rate of the liquid may be simply referred to as "flow rate." As shown in Figure 2, the control unit 10 comprises a flow rate acquisition unit 11, a setting unit 12, and a determination unit 13.

[0021] The flow rate acquisition unit 11 acquires the flow rate. Specifically, the flow rate acquisition unit 11 acquires a signal indicating the flow rate from a flow sensor (not shown) provided by the dewatering machine 9, and converts the signal into a flow rate.

[0022] The setting unit 12 sets a reference value for the flow rate. During periods when the flow rate increases in a time series, the setting unit 12 sets the increased flow rate as a new reference value each time the flow rate increases. During periods when the flow rate decreases in a time series, the setting unit 12 maintains the reference value that was set at the start of that period.

[0023] Figure 3 is a graph showing an example of flow rate and baseline value. In Figure 3, the horizontal axis represents time, and the vertical axis represents flow rate and baseline value. The gray line represents flow rate, and the black line represents baseline value.

[0024] As shown in Figure 3, during periods when the flow rate increases over time, the baseline value also increases in line with the increase in flow rate. During periods when the flow rate decreases over time, the baseline value remains at the value at the beginning of that period. When the flow rate transitions from a period of decrease to a period of increase, the flow rate is reset to the baseline value.

[0025] Let's return to the explanation of the block diagram shown in Figure 2. The determination unit 13 determines that the flow rate has decreased sharply if the flow rate remains below a predetermined multiplier of less than 1 relative to the standard value for a predetermined period of time. The predetermined multiplier may be, for example, 0.94 times, but is not limited to this. The predetermined period may be, for example, 1 minute, but is not limited to this.

[0026] The inventors of this application have found that by comparing the reference value and the flow rate as described above, a sudden decrease in flow rate can be appropriately determined at a level equivalent to visual confirmation by an operator. If a sudden decrease in flow rate can be appropriately determined, various controls performed to return the flow rate to normal can be appropriately executed. These various controls include, for example, controlling the injection rate of chemicals added to the liquid in the coagulation tank 51, or controlling the rotation speed of the screw 92 of the dewatering machine 9.

[0027] As described above, the dehydrator 9 is a screw press type dehydrator. The flow rate used by the determination unit 13 for determination is the flow rate per rotation of the screw 92 of the dehydrator 9. In other words, the flow rate value used by the determination unit 13 for determination is the flow rate per unit time divided by the number of rotations of the screw 92. This allows for an appropriate determination of the state of the dehydrator 9 regardless of the rotation speed of the screw 92.

[0028] Furthermore, the flow rate used by the determination unit 13 for determination may not be the actual measured value acquired by the flow rate acquisition unit 11, but rather the average value of the actual measured values ​​over a certain period in the past. The certain period may be, for example, 5 minutes, but is not limited to this. This reduces the influence of noise and other factors on the determination made by the determination unit 13.

[0029] The storage unit 20 stores information necessary for the control unit 10 to determine a sudden decrease in flow rate. For example, the storage unit 20 stores the flow rate acquired by the flow rate acquisition unit 11, along with the time it was acquired. The storage unit 20 also stores the reference value set by the setting unit 12. Alternatively, the information processing device 1 may not have a storage unit 20 and may be configured to communicate with an external storage device that stores information necessary for the control unit 10 to determine a sudden decrease in flow rate.

[0030] The information processing device 1 may further include an output device, such as a display device, for outputting information stored in the storage unit 20, such as fluctuations in flow rate and reference values ​​over time. The information processing device 1 may also further include an input device for receiving instructions from a user.

[0031] In Figure 1, the information processing device 1 is shown as a separate device from the dehydrator 9. However, the information processing device 1 may be part of the dehydrator 9. In other words, the dehydrator 9 may include the information processing device 1.

[0032] [Control device configuration] Figure 4 is a block diagram showing an example of the configuration of the main components of the control device 3. The control device 3 controls the injection rate of the chemical added to the liquid in the coagulation tank 51 based on the determination result from the information processing device 1. The control device 3 comprises a control unit 30 and a storage unit 40.

[0033] The control unit 30 controls the operation of the injection mechanism (not shown) that injects the chemical agent into the liquid in the coagulation tank 51. As shown in Figure 4, the control unit 30 includes an injection rate control unit 31, a second flow rate acquisition unit 32, a delay timer 33, and a rotation speed control unit 34.

[0034] The injection rate control unit 31 controls the injection rate (drug injection rate) of the drug added to the liquid in the coagulation tank 51. When the information processing device 1 determines that the flow rate has decreased rapidly, the injection rate control unit 31 executes rapid decrease response control, which is a control to respond to the rapid decrease. Rapid decrease response control is a control to increase the flow rate. Specific examples of the rapid decrease response control will be described later.

[0035] The delay timer 33 delays the start of the rapid decrease response control by the injection rate control unit 31 by a predetermined period. That is, the injection rate control unit 31 executes the rapid decrease response control after a predetermined period has elapsed from the time it is determined that the flow rate has decreased rapidly. The predetermined period is, for example, 3 minutes, but is not limited to this.

[0036] If the flow rate decreases, the flow rate may recover quickly even without the injection rate control unit 31 executing sudden decrease response control. In such cases, sudden decrease response control is unnecessary. By delaying the start of sudden decrease response control with the delay timer 33, the injection rate control unit 31 can wait for the start of sudden decrease response control, reducing the possibility of executing unnecessary sudden decrease response control.

[0037] Furthermore, the injection rate control unit 31 performs control to check the flow rate fluctuation by raising or lowering the drug injection rate at regular intervals. This type of control is called normal drug injection rate control. If the injection rate control unit 31 has started controlling the injection rate within a predetermined period prior to the time when it was determined that the flow rate had decreased sharply, it will wait for the sudden decrease response control to be completed.

[0038] During the normal drug injection rate control process, the flow rate may suddenly decrease due to fluctuations in the drug injection rate. In such cases, the flow rate is likely to recover by the end of the normal drug injection rate control process. Therefore, it is highly likely that sudden decrease response control is unnecessary for sudden decreases in flow rate during the normal drug injection rate control process. For this reason, the injection rate control unit 31 can reduce the possibility of executing unnecessary sudden decrease response control by waiting until the end of the normal drug injection rate control process before starting the sudden decrease response control. On the other hand, if the flow rate does not recover after a sudden decrease in flow rate during the normal drug injection rate control process, the injection rate control unit 31 will execute sudden decrease response control.

[0039] The second flow rate acquisition unit 32 acquires the flow rate. The function of the second flow rate acquisition unit 32 is the same as that of the flow rate acquisition unit 11. The second flow rate acquisition unit 32 differs from the flow rate acquisition unit 11 in that it is provided in the control device 3.

[0040] After waiting for the start of the rapid decrease response control as described above, the injection rate control unit 31 compares the flow rate at the time the rapid decrease response control is started with the flow rate before the rapid decrease. If the difference between the flow rate at the time the rapid decrease response control is started and the flow rate before the rapid decrease is within a predetermined threshold, the injection rate control unit 31 cancels the rapid decrease response control.

[0041] If the difference between the flow rate at the time the rapid reduction response control is initiated and the flow rate before the rapid reduction is within a predetermined threshold, it can be said that the flow rate recovered during the period while waiting for the rapid reduction response control to start. In such cases, the injection rate control unit 31 can prevent unnecessary execution of the rapid reduction response control by canceling the control.

[0042] Figures 5 to 10 are graphs showing examples of changes in drug injection rate and flow rate over time. In each graph, the horizontal axis represents time, and the vertical axis represents drug injection rate or flow rate. Solid lines represent drug injection rate, and dashed lines represent flow rate. In each graph, the shaded period is the period during which the determination unit 13 determines that the flow rate has decreased sharply.

[0043] Each graph shows a period that includes both a drug injection rate control period and a period of constant drug injection rate. The drug injection rate control period is the period during which the injection rate control unit 31 performs the normal drug injection rate control described above. The period of constant drug injection rate is the period during which the injection rate control unit 31 does not perform the normal drug injection rate control described above and maintains a constant drug injection rate. However, if the injection rate control unit 31 starts rapid decrease response control, the drug injection rate will fluctuate even during the period of constant drug injection rate. In the control by the injection rate control unit 31, the drug injection rate control period and the period of constant drug injection rate alternate.

[0044] The chemical injection rate control period requires, for example, 10 to 45 minutes, depending on fluctuations in the chemical injection rate. On the other hand, a fixed chemical injection rate period may be set for, for example, 15 minutes. During the fixed chemical injection rate period, the rotation speed control unit 34 may adjust the rotation speed of the screw 92 at regular intervals, for example, every 5 minutes. In this case, the adjustment of the screw rotation speed may be made considering the water content of the dewatered cake or the amount of activated sludge to be processed.

[0045] If a sudden decrease response control is initiated in the middle of a period of maintaining a constant drug injection rate, the drug injection rate will be interrupted for the duration that the sudden decrease response control is in effect. In this case, the drug injection rate may be resumed after the sudden decrease response control ends. Alternatively, if a sudden decrease response control is initiated at the end of the drug injection rate control period, the drug injection rate may be resumed after the sudden decrease response control ends.

[0046] In each graph, time T0 is the time when the drug injection rate transitions from the drug injection rate control period to a fixed drug injection rate period. Time T1 is the time when the determination unit 13 starts determining that the flow rate has decreased sharply. Time T2 is the time when the determination unit 13 ends determining that the flow rate has decreased sharply. Time T3 is the time when the delay in the start of the sharp decrease response control by the delay timer 33 ends.

[0047] Figure 5 is a graph showing an example where the control device 3 is not equipped with a delay timer 33 and the drug injection rate suddenly decreases at a certain time. In the example shown in Figure 5, the injection rate control unit 31 starts the sudden decrease response control at time T1.

[0048] Figure 6 is a graph showing an example where the control device 3 is equipped with a delay timer 33 and the drug injection rate suddenly decreases at a certain point in time. In the example shown in Figure 6, time T2 is later than time T3. That is, the period during which the determination unit 13 determines that the flow rate has suddenly decreased continues even after the delay period set by the delay timer 33 has elapsed. In this example, the injection rate control unit 31 starts the sudden decrease response control at time T3.

[0049] Figure 7 is a graph showing a different example from Figure 6, where the control device 3 is equipped with a delay timer 33 and the drug injection rate suddenly decreases at a certain point in time. In the example shown in Figure 7, time T2 is before time T3. That is, the period during which the determination unit 13 determines that the flow rate has suddenly decreased has ended before the delay period set by the delay timer 33 has elapsed. In this example, at time T3, the determination unit 13 has not determined that the flow rate has suddenly decreased. Therefore, the injection rate control unit 31 does not perform sudden decrease response control.

[0050] Figure 8 is a graph showing an example where the control device 3 is equipped with a delay timer 33 and the flow rate suddenly decreases during the drug injection rate control period. In the example shown in Figure 8, time T2 is after time T3. That is, the period during which the determination unit 13 determines that the flow rate has suddenly decreased continues even after the delay period set by the delay timer 33 has elapsed. However, at the point when the delay period set by the delay timer 33 has elapsed, the drug injection rate control period is still ongoing. In this example, time T2 is before time T0. That is, the period during which the determination unit 13 determines that the flow rate has suddenly decreased has ended before the end of the drug injection rate control period. Therefore, the injection rate control unit 31 does not perform sudden decrease response control.

[0051] Figure 9 is a graph showing a different example from Figure 8, where the control device 3 is equipped with a delay timer 33 and the flow rate decreases sharply during the drug injection rate control period. In the example shown in Figure 9, time T2 is later than time T3 and time T0. That is, the period during which the determination unit 13 determines that the flow rate has decreased sharply continues after the delay period set by the delay timer 33 has elapsed and until the end of the drug injection rate control period. Also, in this example, time T0 is later than time T3. That is, the drug injection rate control period ends after the delay period set by the delay timer 33 has ended. Therefore, the injection rate control unit 31 starts the sharp decrease response control at time T0.

[0052] Furthermore, if the control device 3 is not equipped with a delay timer 33, and the drug injection rate changes sharply during the drug injection rate control period, the change will be the same as in Figure 8 or Figure 9. That is, in this case, the injection rate control unit 31 waits to start the sharp decrease response control until time T0. If time T2 is before time T0, the injection rate control unit 31 does not perform the sharp decrease response control, similar to the example shown in Figure 8. If time T2 is after time T0, the injection rate control unit 31 starts the sharp decrease response control at time T0, similar to the example shown in Figure 9.

[0053] Figure 10 is a graph showing a different example from Figures 8 and 9, where the control device 3 is equipped with a delay timer 33 and the flow rate decreases sharply during the drug injection rate control period. In the example shown in Figure 10, time T2 is later than time T3, similar to the example shown in Figure 9. However, unlike the example shown in Figure 9, time T3 is later than time T0 in the example shown in Figure 10. That is, the delay period due to the delay timer 33 continues even after the end of the drug injection rate control period. Therefore, the injection rate control unit 31 starts the sharp decrease response control at time T3.

[0054] Let's return to the explanation of the block diagram shown in Figure 4. The rotational speed control unit 34 controls the rotational speed of the screw 92 of the dewatering machine 9. The rotational speed control unit 34 may, for example, adjust the rotational speed of the screw 92 at regular intervals, as described above.

[0055] The memory unit 40 stores information necessary for the control unit 30 to determine a sudden decrease in flow rate. For example, the memory unit 40 stores the flow rate acquired by the second flow rate acquisition unit 32 in association with the time it was acquired. The control device 3 may not have a memory unit 40 and may be configured to communicate with an external storage device that stores information necessary for the control unit 30 to determine a sudden decrease in flow rate.

[0056] The control device 3 may further include an output device, such as a display device, for outputting information such as fluctuations in flow rate over time, which is stored in the memory unit 40. The control device 3 may also further include an input device for receiving instructions from the user.

[0057] [Processing in information processing equipment] Figure 11 is a flowchart showing an example of processing (method for determining a sudden decrease in flow rate) in the information processing device 1. In the information processing device 1, first, the flow rate acquisition unit 11 acquires the flow rate of the liquid supplied to the dewatering machine 9 (S11, flow rate acquisition step). Next, the setting unit 12 sets a reference value for determining a sudden decrease in flow rate (S12, setting step).

[0058] The determination unit 13 determines whether the flow rate multiplier to the reference value set by the setting unit 12 has remained below a predetermined multiplier of less than 1 for a predetermined period of time (S13). If the flow rate multiplier to the reference value has not remained below the predetermined multiplier for a predetermined period of time (NO in S13), the information processing device 1 repeats the process from step S11. If the flow rate multiplier to the reference value has remained below the predetermined multiplier for a predetermined period of time (YES in S13), the determination unit 13 determines that the flow rate has decreased sharply (S14, determination step). After that, the information processing device 1 repeats the process from step S11.

[0059] [Processing in the control device] Figure 12 is a flowchart showing an example of processing in the control device 3. Processing in the control device 3 begins when the information processing device 1 determines that the flow rate has decreased sharply. Once processing begins, the injection rate control unit 31 waits until the delay period set by the delay timer 33 ends (S21). Subsequently, if the injection rate control unit 31 has started controlling the injection rate within a predetermined period in the past, it waits until the control of the injection rate is completed (S22).

[0060] Subsequently, the second flow rate acquisition unit 32 acquires the flow rate (S23). The injection rate control unit 31 determines whether the difference between the flow rate acquired by the second flow rate acquisition unit 32 in step S23 and the flow rate before it was determined that the flow rate had decreased sharply is within a predetermined threshold (S24). The predetermined threshold is, for example, 6% of the flow rate before it was determined that the flow rate had decreased sharply, but is not limited to this.

[0061] The flow rate data used by the injection rate control unit 31 for determination in step S24, before it is determined that the flow rate has decreased sharply, may be the data acquired by the flow rate acquisition unit 11 in step S11. In this case, the injection rate control unit 31 may acquire this data from the information processing device 1. Alternatively, the second flow rate acquisition unit 32 may continuously acquire flow rate data and store it in the storage unit 40, regardless of the determination in the information processing device 1. In this case, the injection rate control unit 31 may acquire the flow rate data from the storage unit 40 before it is determined that the flow rate has decreased sharply.

[0062] If the difference between the flow rate acquired by the second flow rate acquisition unit 32 and the flow rate before the sudden decrease in flow rate was determined is not within a predetermined threshold (NO in S24), it can be said that the sudden decrease in flow rate is continuing. In this case, the injection rate control unit 31 executes sudden decrease response control (S25). The details of the sudden decrease response control will be described later.

[0063] If the difference between the flow rate acquired by the second flow rate acquisition unit 32 and the flow rate before the sudden decrease in flow rate was determined to be within a predetermined threshold (YES in S24), it can be said that the sudden decrease in flow rate has been resolved. In this case, the injection rate control unit 31 stops the sudden decrease response control (S26). After the sudden decrease response control (S25) or the sudden decrease response control is stopped (S26), the control device 3 repeats the process from step S21.

[0064] [Control to respond to sudden decrease in power] Figure 13 is a flowchart showing an example of the content of the rapid decrease response control in Figure 12. Figure 14 is a flowchart showing an example of the content of the first adjustment process in Figure 13. Figure 15 is a flowchart showing an example of the content of the second adjustment process in Figure 13. In the rapid decrease response control, in addition to the processes shown in Figures 13 to 15, the second flow rate acquisition unit 32 performs a process to acquire the flow rate at predetermined time intervals. The predetermined time interval is, for example, 1 minute, but is not limited to this.

[0065] As shown in Figure 13, in the rapid decrease response control, the injection rate control unit 31 first increases the drug injection rate to a predetermined value (S31). The predetermined value is, for example, 0.05% of the original value, but is not limited to this. In this state, the injection rate control unit 31 waits for a predetermined period of time (S32). The length of the predetermined period in step S32 can be any length of time for the effect of the increase in the drug injection rate in step S31 to become apparent, for example, 10 minutes, but is not limited to this.

[0066] After step S32, the injection rate control unit 31 determines whether the current flow rate is greater than the flow rate before the drug injection rate was increased in step S31 (S33). The current flow rate is the most recent flow rate at the time of processing, among the flow rates acquired by the second flow rate acquisition unit 32 at predetermined time intervals. If the current flow rate is greater than the flow rate before the drug injection rate was increased (YES in S33), the injection rate control unit 31 determines whether the current flow rate is greater than the most recent flow rate (S34). The most recent flow rate is the flow rate acquired by the second flow rate acquisition unit 32 one time before the current flow rate, among the flow rates acquired at predetermined time intervals.

[0067] If the current flow rate is greater than the most recent flow rate (YES in S34), it is considered that the flow rate is continuing to increase. In this case, the injection rate control unit 31 waits for a predetermined period (S35), and then executes step S34 again. The length of the predetermined period in step S35 may be greater than or equal to the predetermined time interval at which the second flow rate acquisition unit 32 acquires the liquid flow rate, for example, the same length.

[0068] If the current flow rate is not greater than the most recent flow rate (NO in S34), it is considered that the increase in flow rate has ended. In this case, the injection rate control unit 31 determines whether the ratio of the current flow rate to the flow rate before the liquid drug injection rate was increased in step S31 is greater than or equal to a predetermined value (S36). The predetermined value in step S36 is any value that can be judged as indicating a significant increase in flow rate, and may be, for example, 1.06 times, but is not limited to this.

[0069] If the ratio of the current flow rate to the flow rate before increasing the drug injection rate of the liquid is greater than or equal to a predetermined value (YES in S36), then it can be said that the flow rate has significantly increased due to the increase in the drug injection rate in step S31. In this case, the injection rate control unit 31 performs the first adjustment process (S37).

[0070] On the other hand, if the ratio of the current flow rate to the flow rate before increasing the drug injection rate of the liquid is not greater than or equal to a predetermined value (NO in S36), it can be said that the flow rate did not increase significantly due to the increase in the drug injection rate in step S31. In this case, the injection rate control unit 31 performs a second adjustment process (S38). The injection rate control unit 31 also performs a second adjustment process if it determines in step S33 that the current flow rate is not greater than the flow rate before increasing the drug injection rate (NO in S33).

[0071] [First adjustment process] The first adjustment process is a process that attempts to further improve the flow rate by further increasing the drug injection rate if the flow rate has significantly increased due to the increase in the drug injection rate in step S31. As shown in Figure 14, in the first adjustment process, the injection rate control unit 31 increases the drug injection rate by a predetermined value (S41). The predetermined value in step S41 is, for example, 0.05% of the original value, as in step S31 described above, but is not limited to this. In this state, the injection rate control unit 31 waits for a predetermined period (S42). The length of the predetermined period in step S42 can be any length for which the effect of the increase in the drug injection rate in step S41 is expected to become apparent, for example, 10 minutes, as in step S32 described above, but is not limited to this.

[0072] After step S42, the infusion rate control unit 31 determines whether the current flow rate is greater than the flow rate before the drug injection rate was increased in step S41 (S43). If the current flow rate is greater than the flow rate before the drug injection rate was increased (YES in S43), the infusion rate control unit 31 determines whether the current flow rate is greater than the most recent flow rate (S44).

[0073] If the current flow rate is greater than the most recent flow rate (YES in S44), the injection rate control unit 31 waits for a predetermined period (S45), and then executes step S44 again. The predetermined period in step S45 may be longer than or equal to the predetermined time interval at which the second flow rate acquisition unit 32 acquires the liquid flow rate, for example, the same length.

[0074] If the current flow rate is not greater than the most recent flow rate (NO in S44), the injection rate control unit 31 determines whether the ratio of the current flow rate to the flow rate before increasing the liquid injection rate in step S41 is greater than or equal to a predetermined value (S46). The predetermined value in step S46 is, for example, 1.06 times, but is not limited to this.

[0075] If the ratio of the current flow rate to the flow rate before increasing the drug injection rate of the liquid is greater than or equal to a predetermined value (YES in S46), then it can be said that the flow rate has increased significantly further due to the increase in the drug injection rate in the last executed step S41. In this case, the injection rate control unit 31 repeats the process again from step S41.

[0076] On the other hand, if the ratio of the current flow rate to the flow rate before increasing the drug injection rate of the liquid is not greater than or equal to a predetermined value (NO in S46), it can be said that the flow rate did not increase significantly due to the increase in the drug injection rate in the last executed step S41. In this case, the injection rate control unit 31 decreases the drug injection rate by a predetermined value (S47) and terminates the first adjustment process. The predetermined value in step S47 is the same as the increase in the drug injection rate in the last executed step S41. In other words, step S47 is the process of returning the drug injection rate to the value before the last executed step S41.

[0077] Furthermore, if the current flow rate in step S43 is not greater than the flow rate before increasing the drug injection rate (YES in S43), it can be said that the flow rate did not significantly increase due to the increase in the drug injection rate in step S41. In this case as well, the injection rate control unit 31 decreases the drug injection rate to a predetermined value (S47) and terminates the first adjustment process.

[0078] [Second adjustment process] The second adjustment process attempts to improve the flow rate by decreasing the drug injection rate if the flow rate did not significantly increase due to the increase in the drug injection rate in step S31. As shown in Figure 15, in the second adjustment process, the injection rate control unit 31 decreases the drug injection rate by a predetermined value (S51). The predetermined value in step S51 is the same as the increase in the drug injection rate in step S31. In other words, step S51 is the process of returning the drug injection rate to the value before step S31.

[0079] After step S51, the injection rate control unit 31 further reduces the drug injection rate to a predetermined value (S52). The predetermined value in step S52 may be the same as or different from the reduction in the drug injection rate in step S51. In this state, the injection rate control unit 31 waits for a predetermined period of time (S53). The length of the predetermined period in step S53 may be any length of time for the effect of the reduction in the drug injection rate in step S52 to become apparent, for example, 10 minutes as in step S32 described above, but is not limited to this.

[0080] After step S53, the infusion rate control unit 31 determines whether the current flow rate is greater than the flow rate before the drug injection rate was reduced in step S52 (S54). If the current flow rate is greater than the flow rate before the drug injection rate was reduced (YES in S54), the infusion rate control unit 31 determines whether the current flow rate is greater than the most recent flow rate (S55).

[0081] If the current flow rate is greater than the most recent flow rate (YES in S55), the injection rate control unit 31 waits for a predetermined period (S56), and then executes step S55 again. The predetermined period in step S56 may be longer than or equal to the predetermined time interval at which the second flow rate acquisition unit 32 acquires the liquid flow rate, for example, the same length.

[0082] If the current flow rate is not greater than the most recent flow rate (NO in S55), the injection rate control unit 31 determines whether the ratio of the current flow rate to the flow rate before the liquid drug injection rate was reduced in step S52 is greater than or equal to a predetermined value (S57). The predetermined value in step S57 is, for example, 1.06 times, but is not limited to this.

[0083] If the ratio of the current flow rate to the flow rate before the reduction in the liquid drug injection rate is greater than or equal to a predetermined value (YES in S57), then it can be said that the flow rate has significantly increased due to the reduction in the drug injection rate in the last executed step S52. In this case, the injection rate control unit 31 repeats the process again from step S52.

[0084] On the other hand, if the ratio of the current flow rate to the flow rate before the drug injection rate of the liquid is reduced is not greater than or equal to a predetermined value (NO in S57), it can be said that the flow rate did not increase significantly due to the reduction in the drug injection rate in the last executed step S52. In this case, the injection rate control unit 31 increases the drug injection rate to a predetermined value (S58) and terminates the second adjustment process. The predetermined value in step S58 is the same as the reduction in the drug injection rate in the last executed step S52. In other words, step S58 is the process of returning the drug injection rate to the value before the last executed step S52.

[0085] Furthermore, if the current flow rate in step S54 is not greater than the flow rate before the drug injection rate was reduced (NO in S54), it can be said that the flow rate did not significantly increase due to the reduction in the drug injection rate in step S52. In this case as well, the injection rate control unit 31 increases the drug injection rate to a predetermined value (S58) and terminates the second adjustment process.

[0086] Furthermore, depending on the cause of the sudden decrease in flow rate, it is possible that the flow rate may not recover even with the sudden decrease response control described above. In this case, in the example of the process described above, the injection rate control unit 31 will determine NO in step S33 and proceed to the second adjustment process, then determine NO again in the first step S54, and forcibly terminate the sudden decrease response control while the flow rate has not recovered. In this case, the injection rate control unit 31 may store in the memory unit 40 that the flow rate did not recover due to the sudden decrease response control. This allows the user to confirm the situation in which the flow rate did not recover due to the sudden decrease response control and consider countermeasures.

[0087] (modified version) As described above, in the flocculator 5, images of the flocs in the coagulation tank 51 can be captured by the imaging device 72. The control device 3 may be capable of detecting an excess or deficiency of the drug injection rate based on the images of the flocs.

[0088] In this case, the control device 3 may perform rapid decrease response control by combining the determination result from the information processing device 1 and the detection result based on the flock image. For example, if the information processing device 1 determines that the flow rate has decreased rapidly and the control device 3 detects insufficient drug injection based on the image, the control device 3 may perform only the first adjustment process described above as rapid decrease response control. Also, for example, if the information processing device 1 determines that the flow rate has decreased rapidly and the control device 3 detects over-injection based on the image, the control device 3 may skip step S51 of the second adjustment process described above and perform the processes from step S52 onwards as rapid decrease response control.

[0089] Furthermore, if, for example, the information processing device 1 determines that the flow rate has decreased sharply, and the control device 3 does not detect either insufficient or excessive drug injection through image analysis, then it is unlikely that adjusting the drug injection rate will improve the flow rate. In this case, the control device 3 does not need to perform sharp decrease response control.

[0090] Furthermore, if the information processing device 1 does not determine that the flow rate has decreased sharply, and the control device 3 detects an overdose of medication via image, then an overdose of medication has occurred, but the flow rate has not decreased. In this state, there is no problem with the dehydration performance itself, but it becomes a cost problem because the medication is consumed unnecessarily. In this case, the overdose of medication can be quickly resolved by applying the normal medication rate control described above.

[0091] Furthermore, as mentioned above, during a certain period of chemical injection, the rotation speed control unit 34 can be used to adjust the rotation speed of the screw 92 at regular intervals, for example, every 5 minutes. This control involves setting a desired range for moisture content and sludge treatment volume in advance, and adjusting the rotation speed to bring it closer to the desired range if the predicted moisture content and / or sludge treatment volume are not within that range. Here, the predicted moisture content is, for example, a value of moisture content predicted by machine learning from parameters including sludge flow rate.

[0092] If the information processing device 1 determines that the sludge flow rate has decreased sharply, and the control device 3 executes a control to respond to the sharp decrease, but the sludge flow rate does not recover as a result of the control, then in most cases the predicted moisture content and / or sludge flow rate will have deviated from the desired range. In this case, the rotation speed control unit 34 can mitigate the effects of the sharp decrease in sludge flow rate by controlling the rotation speed of the screw 92 as described above.

[0093] For example, if it is desired to reduce the water content of the flocculated sludge, the rotation speed control unit 34 slows down the rotation speed of the screw 92. Conversely, if it is desired to ensure a sufficient amount of flocculated sludge can be processed, the rotation speed control unit 34 increases the rotation speed of the screw 92. In this way, by accelerating and decelerating the rotation speed of the screw 92 as needed, the rotation speed control unit 34 can mitigate the effects of a sudden decrease in flow rate. Whether to prioritize the water content of the flocculated sludge or ensuring sufficient processing volume is determined, for example, by user input.

[0094] [Examples of implementation using software] The function of the information processing device 1 (hereinafter referred to as "the device") is a program for determining a sudden decrease in flow rate to make the device function as a computer, and this can be realized by a program for making each control block of the device (especially each part included in the control unit 10) function as a computer.

[0095] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, the functions described in each of the embodiments are realized.

[0096] The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium.

[0097] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0098] Furthermore, each process described in the above embodiments may be performed by AI (Artificial Intelligence). In this case, the AI ​​may operate on the control device described above, or it may operate on other devices (for example, an edge computer or a cloud server).

[0099] 〔summary〕 This invention can also be expressed as follows:

[0100] An information processing apparatus according to aspect 1 of the present invention includes a flow rate acquisition unit that acquires the flow rate of a liquid supplied to a dewatering machine that dewaters a liquid discharged from a flocculation tank to which a chemical agent for flocculating the suspended solids is added; a setting unit that sets a reference value for the flow rate; and a determination unit that determines that the flow rate has decreased sharply if the ratio of the flow rate to the reference value remains below a predetermined ratio of less than 1 for a predetermined period of time. The setting unit sets the flow rate as a new reference value each time the flow rate increases during a period in which the flow rate increases in a time series, and maintains the reference value set at the start of the period during a period in which the flow rate decreases in a time series.

[0101] In the information processing device according to aspect 2 of the present invention, in aspect 1, the dewatering machine is a screw press type dewatering machine, and the flow rate is the flow rate of the liquid supplied to the dewatering machine per rotation of the screw of the dewatering machine.

[0102] The dehydrator according to embodiment 3 of the present invention is equipped with an information processing device according to embodiment 1 or 2.

[0103] A control device according to aspect 4 of the present invention includes an injection rate control unit for controlling the injection rate of the drug, wherein when the information processing device according to claim 1 determines that the flow rate has decreased rapidly, the injection rate control unit executes a rapid decrease response control, which is the control for responding to the rapid decrease.

[0104] In the control device according to aspect 5 of the present invention, in aspect 4, the injection rate control unit executes the rapid decrease response control after a predetermined period has elapsed from the time it is determined that the flow rate has rapidly decreased.

[0105] In the control device according to embodiment 6 of the present invention, in embodiment 4 or 5, if the injection rate control unit has started controlling the injection rate within a predetermined period in the past from the time it was determined that the flow rate had decreased sharply, the control unit waits for the sudden decrease response control to be completed.

[0106] A control device according to embodiment 7 of the present invention further comprises a second flow rate acquisition unit for acquiring the flow rate, in embodiment 5 or 6, wherein the injection rate control unit cancels the sudden reduction response control if the difference between the flow rate at the time the sudden reduction response control is started and the flow rate before the sudden reduction is within a predetermined threshold.

[0107] In any of embodiments 4 to 7, the control device according to embodiment 8 of the present invention is a screw press type dewatering machine, and includes a rotation speed control unit that controls the rotation speed of the screw of the dewatering machine, wherein, after the rapid reduction response control, if the sludge flow rate is not within a predetermined range, the rotation speed control unit controls the rotation speed of the screw of the dewatering machine.

[0108] A method for determining a sudden decrease in flow rate according to aspect 9 of the present invention is a method for determining a sudden decrease in flow rate that is performed by one or more information processing devices, and includes: a flow rate acquisition step of acquiring the flow rate of a liquid supplied to a dewatering machine that dewaters the liquid while transporting the liquid discharged from a flocculation tank to which a chemical agent for flocculating the suspended solids is added to a liquid containing suspended solids; a setting step of setting a reference value for determining a sudden decrease in the flow rate; and a determination step of determining that the flow rate has suddenly decreased if the ratio of the flow rate to the reference value is less than a predetermined ratio of less than 1 for a predetermined period of time, wherein the setting step sets the flow rate as the reference value each time the flow rate increases during a period in which the flow rate increases in a time series, and maintains the reference value set at the start of the period during a period in which the flow rate decreases in a time series.

[0109] The flow rate sudden decrease determination program according to aspect 10 of the present invention is a flow rate sudden decrease determination program for causing a computer to function as an information processing device as in aspect 1, wherein the computer functions as the flow rate acquisition unit, the setting unit, and the determination unit.

[0110] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0111] 1. Information Processing Device 3. Control device 9 Dehydrator 11 Flow rate acquisition section 12. Settings section 13 Judgment section 31 Injection Rate Control Unit 32 2nd flow rate acquisition section 34. Rotational Speed ​​Control Unit

Claims

1. A flow rate acquisition unit acquires the flow rate of the liquid supplied to a dewatering machine that dewaters the liquid while transporting the liquid discharged from a coagulation tank to which a chemical agent that coagulates the suspended solids is added, A setting unit for setting the reference value of the flow rate, The system includes a determination unit that determines that the flow rate has decreased sharply if the ratio of the flow rate to the reference value remains below a predetermined ratio of less than 1 for a predetermined period of time. The setting unit is, During the period in which the flow rate increases in a time series, each time the flow rate increases, the flow rate is set as a new reference value. During the period in which the flow rate decreases in a time series, the reference value set at the start of that period is maintained. Information processing device.

2. The aforementioned dehydrator is a screw press type dehydrator, The flow rate is the flow rate of the liquid supplied to the dewatering machine per rotation of the screw of the dewatering machine. The information processing apparatus according to claim 1.

3. A dehydrator comprising the information processing device described in claim 1 or 2.

4. The system includes an injection rate control unit that controls the injection rate of the aforementioned drug, If the information processing device according to claim 1 determines that the flow rate has decreased sharply, the injection rate control unit executes the sharp decrease response control, which is the control to respond to the sharp decrease. Control device.

5. The injection rate control unit executes the rapid decrease response control after a predetermined period has elapsed from the time it is determined that the flow rate has decreased rapidly. The control device according to claim 4.

6. If the injection rate control unit has started controlling the injection rate within a predetermined period prior to the time when it was determined that the flow rate had decreased sharply, it will wait for the sharp decrease response control to be completed. The control device according to claim 4.

7. The system further includes a second flow rate acquisition unit that acquires the aforementioned flow rate, The injection rate control unit shall discontinue the rapid reduction control if the difference between the flow rate at the time the rapid reduction control is initiated and the flow rate before the rapid reduction is within a predetermined threshold. The control device according to claim 5 or 6.

8. The aforementioned dehydrator is a screw press type dehydrator, The dewatering machine is equipped with a rotation speed control unit that controls the rotation speed of the screw, After the rapid decrease response control, if the sludge flow rate is not within a predetermined range, the rotation speed control unit controls the rotation speed of the screw of the dewatering machine. The control device according to claim 4.

9. A method for determining a sudden decrease in flow rate, which is performed by one or more information processing devices, A flow rate acquisition step to acquire the flow rate of the liquid supplied to a dewatering machine that dewaters the liquid while transporting the liquid discharged from a coagulation tank to which a chemical agent for coagulating the suspended solids is added, A setting step to set a reference value for determining a sudden decrease in the flow rate, The process includes a determination step of determining that the flow rate has decreased sharply if the ratio of the flow rate to the reference value remains below a predetermined ratio of less than 1 for a predetermined period of time. The aforementioned setup step is, During the period in which the flow rate increases in a time series, the flow rate is set as the reference value each time the flow rate increases. During the period in which the flow rate decreases in a time series, the reference value set at the start of that period is maintained. Method for determining a sudden decrease in flow rate.

10. A program for determining a sudden decrease in flow rate to cause a computer to function as an information processing device according to claim 1, wherein the program for determining a sudden decrease in flow rate causes the computer to function as the flow rate acquisition unit, the setting unit, and the determination unit.

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