JPH084797B2 - Flow rate controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a flow velocity control device for mixed water containing sludge and other precipitates.

B. Summary of the Invention The present invention operates a pump to supply sludge mixed water in a mixed water tank containing sediment such as sludge to a water supply pipeline, and a detection signal from a concentration detector provided in the water pipeline. In the flow rate control device for controlling the pump by means of the above, the first and second concentration detectors are provided on the upper surface and the lower surface of the water supply pipe, and the flow velocity of the sludge mixed water is changed according to the difference between these detectors. Control the pump,
In addition, by selecting the feed water arrival position signal when the water arrives at the water pipes with different cross-sectional areas and the pump drive control signal according to the cross-sectional area from the flow velocity change signal, the flow rate in the mud pipe It is possible to control continuously, and to perform optimum control according to the water supply pipeline.

C. Conventional technology For example, sludge management is important in a sewage treatment plant, especially a sewage treatment plant using the activated sludge method. The sewage organic matter reacts with the microorganisms in the activated sludge in the aeration tank, but a part of the organic matter is taken up by the microorganisms, so that the sludge increases. Sludge and supernatant water are separated in the final settling basin in the next stage, but because the amount of settled sludge is increasing, the whole sludge cannot be returned to the aeration tank. Therefore, excess sludge is treated as excess sludge by extracting, concentrating, digesting, dehydrating, incinerating, etc. Corresponding to this excess sludge is return sludge returned to the aeration tank, and the return sludge decreases as the amount of excess sludge withdrawn increases. Therefore, in the process of treating sewage and sludge, it is necessary to measure the flow rate and the concentration of surplus sludge and return sludge in order to control the amount. In addition, there are two types of sludge treatment methods: one that is performed at each sewage treatment plant and one that concentrates sludge generated at multiple sewage treatment plants. In recent years, such as land, environment and efficiency. Due to problems, the centralized processing method is often used.

FIG. 3 is a block diagram showing an example of a conventional flow velocity control device using a centralized processing system. In this figure, reference symbol T indicates a sludge sending side for sending sludge, and B indicates a sludge receiving side for receiving sludge and treating it. A sludge tank that temporarily stores sludge on the mud sending side T
100, a sludge pump 101 for sending the sludge in the sludge tank 100 to the mud feed line 102 by the operation of the pump, a treated water tank 110 for storing the treated water, and a sludge pipe line 102 for the treated water in the treated water tank 110 by the operation of the pump. A water supply pump 111 is provided for sending to.

The mud sending line 102 is a pipe that connects the mud sending side T and the mud receiving side R and sends sludge to the mud receiving side R. Reference numeral 103 is a densitometer attached to the mud-sending conduit 102 for measuring the sludge concentration. Further, the sludge receiving side R temporarily supplies the sludge valve 104 that supplies sludge to the sludge layer 103 by operating the valve, the treated water valve 105 that supplies treated water to the treated water tank by operating the valve, and the treated water used in the water treatment facility. It comprises a treated water tank 106 for storing and a mud tank 107 for temporarily storing mud used in sludge treatment equipment. The densitometer 103 should have a short output response time to changes in the active concentration for switching the valve, and have a wide detection sensitivity range from low concentration to high concentration (concentration of treated water to concentrated active concentration). Has become. As a method for measuring the sludge concentration in the sludge pipe line 102, there are generally an ultrasonic method and a light scattering method.The former is a concentration measuring method using attenuation of ultrasonic waves by sludge, and the latter uses light scattering. This is a method of measuring the concentration.

In this light scattering method, since sludge near the glass surface is measured, even if air bubbles are mixed in, the effect thereof is relatively small. Therefore, the light scattering method enables continuous measurement, and is widely used for measurement for returning sludge in a treatment plant, in-line monitoring of excess sludge, and valve control in a sludge centralized treatment system.

D. Problems to be Solved by the Invention In such a conventional flow velocity control device, as shown in FIG. 3, in order to prevent the sludge from spoiling in the sludge pipe line 102, the treated water (the sewage is kept in It is filled with treated relatively clean water. Then, when sludge is accumulated in the sludge tank 102 and it is time to send mud, the mud sending pump 101 is started and the sludge in the sludge tank 100 is pressure-fed to the mud sending line 102. The treated water in the pipeline 102 is pushed and moves. At this time, the sludge valve 104 is closed and the treated water valve 105
Is opened, and the treated water in the mud transport line 102 is the mud receiving side R
It is stored in the treated water tank 106. When the sludge tank 100 runs out of sludge on the mud sending side T, the mud sending pump 101 is stopped, the water sending pump 111 is started, and the treated water in the treated water tank 110 is sent out. On the receiving side R, when the arrival of sludge is detected by the densitometer 103 provided in the mud sending line 102, the sludge valve 104 is opened, the treated water valve 105 is closed, and the sludge is deposited on the sludge tank. Sent to 107. After that, the concentration meter 103 measures the completion of the sludge passage from the sludge concentration. In this way, when the inside of the mud-sending conduit 102 becomes only treated water again, the water-sending pump 111 is stopped and the sludge valve 104 is closed.

In the above flow rate control device, when a mixed liquid such as sludge passes through the long-distance sludge pipeline 102, it is necessary to optimize the flow velocity of the fluid to improve the efficiency of the entire system. However, for example, if the flow velocity in the pipe is too high, the sludge pipeline
Since the loss due to the frictional resistance in 102 becomes large, the load of the pump becomes excessive, the electricity cost is increased, and the inner surface of the sludge pipeline 102, the valve, etc. are consumed quickly. Therefore, in such a control device, the pressure on the mud sending side T is increased, and therefore the equipment must be able to withstand it. If the flow velocity is too low, it takes a long time to send the mud, and if it contains a substance that easily precipitates, it precipitates during the mud sending to narrow the pipeline or change the composition. There is an inconvenience.

Therefore, the present invention obtains the concentration detection difference between both detectors by providing concentration detectors on the upper surface and the lower surface of the mud transport line,
An object of the present invention is to provide a flow velocity control device capable of grasping the sludge condition in the mud transport line and controlling the flow velocity in the mud transport line.

E. Means for Solving the Problems As a means for solving the above problems, the present invention provides a sludge mixed water in a mixed water tank by operating a pump to supply it to a water supply pipeline, and to provide the water supply pipeline. In the flow velocity control device, which detects the concentration of the sludge mixed water sent by the concentration detector, controls the pump by detecting the concentration of the mixed water, and controls the flow rate of the sludge mixed water flowing in the water pipe. A first concentration detector provided on the upper surface of the passage, a second concentration detector provided on the lower surface of the water supply conduit, a flow meter provided on the water supply conduit, the first and second concentrations An arithmetic unit for obtaining the difference between the concentration detection signals detected by the detector, a control circuit for outputting a pump drive control signal by the arithmetic output signal from the arithmetic unit and the flow rate signal sent from the flow meter, and this control circuit The pump drive control signal sent from Pump drive device for driving a pump, and when sludge mixed water reaches the water supply pipes having different cross-sectional areas obtained from the first or second concentration detector via the first or second signal converter, It comprises a selection circuit for selecting a pump drive control signal corresponding to the cross-sectional area of the water supply line based on a sludge mixed water arrival position signal indicating a position and a flow rate change signal indicating a change in flow rate sent from the flow meter. It is characterized by

F. Action In this device, the concentration detection difference between the concentration detectors on the upper and lower surfaces of the water supply pipeline is calculated, and the flow of sludge mixed water in the water supply pipeline is grasped by grasping the flow of sludge mixed water in the water supply pipeline from this concentration detection difference. To achieve an optimum flow velocity, and the sludge mixed water arrival position signal indicating the position when the sludge mixed water arrives at the sludge conduits with different cross-sectional areas, and the flow rate sent from the flowmeter. The pump drive control signal corresponding to the cross-sectional area of the mud feeding line is selected on the basis of the flow rate changing signal indicating the change of No. 1, and the optimum flow rate control according to the mud feeding line is performed.

G. Example Next, an example of the present invention will be described with reference to FIG.
FIG. 1 is a circuit diagram showing a first embodiment of the present invention. In this figure, reference numeral 1 is a sludge tank, and sludge is stored in this sludge tank 1. Reference numeral 2 denotes a pump, which drives the pump 2 by a pump drive device 12 which will be described later to feed the sludge in the sludge tank 1 to the sludge feeding line 3. As shown in FIG. 3, this mud-sending conduit 3 is piped to a treated water tank via a sludge tank and a treated-water valve via a sludge valve. Detectors 5 and 6 are provided. The flow meter 4 measures the flow rate of sludge passing through the mud-sending conduit 3 in which the pump 2 is driven from the pipe cross-sectional area S and the average flow velocity V, and obtains a flow signal S4.
The concentration detector 5 is a detector mounted on the upper surface of the sludge pipeline 3, the concentration detector 6 is a detector mounted on the lower surface of the sludge pipeline 3, and these detectors 5, 6 are, for example, cross-scatterers. The sludge concentration is detected by the method. Reference numeral 7 is a flow rate converter, which converts the flow rate of sludge measured by the flow meter 4 into an electric signal proportional to the flow rate and outputs a flow rate signal Q. Reference numerals 8 and 9 denote concentration converters. The converters 8 and 9 convert the detection signals detected by the concentration detectors 5 and 6 into concentration detection signals C8 and S9. Reference numeral 10 is a calculator, and in this calculator 10, the density detection signal S
The operation output signal α corresponding to 8, S9 is obtained. 11 is a control circuit,
In this circuit 11, a pump drive control signal r is obtained based on the operation output signal α and the flow rate signal Q. The pump controller 12 controls the output of the pump 2.

Next, the operation of the first embodiment will be described. now,
When the flow velocity in the mud transport line 3 becomes slow, the suspension in the fluid precipitates, the lower part of the line loses transparency and the upper part becomes transparent, and a difference appears between the concentration detection signals S8 and S9. In this case, control is performed to drive the pump drive device 12 to stop the sludge flow velocity in the mud feed line 3, and this is performed by the pump drive control signal r of the control circuit 11. Now, it is assumed that the sludge is flowing at a flow rate Q (pipe cross-sectional area S, average flow velocity V) that the pump is driving. At this time, the concentration detection signals S8, S9 are calculated by the calculator 10 as α = f (S _A , S _B ). Control circuit 11
The concentration detection signal α and the output signal Q of the flow meter 4 are input to the pump, and the output: r corresponding to this input is output to the pump drive device 12
Sent to

The difference between S8 and S9 indicates that the suspension in the fluid is settled because the flow rate is too slow. Therefore, the following is an example of control to prevent this.

(Pump drive is pump output flow rate for input signal r Suppose that it has the property of. ) Α = f (S _A , S _B ) = K ₁ (S _B −S _A ) If α> α ₀ then r = K ₂ (Q + β) If α ≦ α ₀ then r = K ₂ (Q−β) K ₁ , K ₂ , α, β, r, α ₀ are positive numbers Qmin is the longest time allowed for mud transport, or pump characteristics. Qmax is a constant determined from the protection of each device or pump characteristics. Is.

Therefore, the average flow velocity V (= Q /
S) can be controlled.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram showing a second embodiment of the present invention. This circuit diagram shows a circuit for controlling the flow rate when the tube cross-sectional areas S are different (S1, S2 ...). The same components as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted. Reference symbols S1 to S3 are mud-sending conduits having different cross-sectional areas, and A to C are units composed of a concentration detection, calculation and control circuit having the same structure as the flow velocity control circuit of FIG. Reference numeral 20 denotes a selection circuit to which the flow rate change signal ri sent from the control circuit 11 of the unit A and the sludge arrival position signal (obtained from the signal S8 or the signal S9) x ₁ are input. The selection circuit 20 inputs the flow rate change signal r ₂ and the sludge arrival position signal x ₂ from the unit B, and the flow rate change signal r ₃ and the sludge arrival position signal x ₃ from the unit C. There is.

Next, the operation of the second embodiment will be described. For example, assume that sludge is being washed away with treated water. Here, S8 or S9 indicates that the sludge has reached this position.
And when α> α ₀ as described above, When α ≦ α However, S ₀ is the cross-sectional area of the pump outlet S ₁ is the cross-sectional area of the measurement position (sludge arrival position), that is, the signal x ₁ of the sludge arrival position (obtained from S8 or S9) and the signal r ₁ for changing the flow rate are input to the selection circuit. And outputs r. Next, the optimum flow rate obtained at x ₁ is maintained until the position signal x ₂ from the detection unit provided at the position where the sludge has a different cross-sectional area S ₂ is input to the selection circuit. flow rate of r = r ₂ r ₂ is obtained that against the cross-sectional area S ₂ in the same manner in x ₂ is controlled.

Similarly, the pump output is controlled so that the optimum flow velocity is obtained according to the cross-sectional area at each position.

As described above, according to the present embodiment, there is a difference in concentration between the upper and lower sides in the mud transport line, and if the difference is within the set value, it is considered that no precipitation has occurred, the flow velocity is reduced, and the concentration is increased. When it occurs, the flow rate in the mud-sending pipeline can be kept optimum because the flow rate is increased as if precipitation had occurred.

Incidentally, in the above embodiment, the case of sending the sewage sludge was described, but the present invention is not limited to this.
In addition to this, it is similarly applied to flow rate control of mixed water containing sediment such as tap water sludge, chemicals and food materials. In this case, what corresponds to sludge is mixed water, and the mud-sending conduit becomes a water-sending conduit for sending the mixed water.

H. Effect of the Invention As described above, according to the present invention, the sludge settling condition in the sludge feeding line can be grasped from the concentration detection difference between the concentration detectors on the upper surface and the lower surface of the sludge feeding line. It is possible to continuously control the flow rate inside. Further, even when the cross-sectional area of the mud transport line is not uniform, it is possible to perform optimum flow velocity control according to the mud transport line.

Therefore, the flow velocity in the mud transmission line will not be too high, which will increase the loss in the line and overload the pump, and the flow velocity will not be too high, so that the equipment will be consumed faster and the pressure resistance will be increased. No need. Furthermore, because the flow velocity in the pipeline does not become too small and the suspension does not settle in the pipeline, optimal flow velocity control that does not block the pipeline or alter the fluid components in the pipeline Is done.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a second embodiment of the present invention, and FIG. 3 is a configuration diagram showing an example of a conventional flow velocity control device. is there. 1 …… Sludge tank, 2 …… Pump, 3 …… Mudging pipeline, 4 ……
Flowmeter, 5,6 ... Concentration detector, 10 ... Calculator, 11 ... Control circuit, 12 ... Pump drive device, S1 to S3 ... Sludging lines with different cross sections, 20 ... Selection circuit .

Claims (2)

[Claims] 1. A sludge mixed water in a mixed water tank is supplied to a water supply pipe by operating a pump, and the concentration of the sludge mixed water sent by a concentration detector provided in the water supply pipe is detected to detect the sludge. In the flow velocity control device for controlling the pump by detecting the concentration of the mixed water, and controlling the flow rate of the sludge mixed water flowing in the water supply pipe,
A first concentration detector provided on the upper surface of the water supply conduit, a second concentration detector provided on the lower surface of the water supply conduit, a flow meter provided on the water supply conduit, and the first and second An arithmetic unit for obtaining the difference between the concentration detection signals detected by the second concentration detector;
A control circuit that outputs a pump drive control signal according to a calculation output signal from this arithmetic unit and a flow rate signal sent from the flow meter, and a pump drive device that controls the pump with the pump drive control signal sent from this control circuit. A flow velocity control device comprising: 2. A sludge mixed water in a mixed water tank is supplied to a water supply pipe by operating a pump, the concentration of sludge mixed water sent by a concentration detector provided in the water supply pipe is detected, and the mixture is mixed. In the flow velocity control device for controlling the pump by controlling the concentration to control the flow rate of the sludge mixed water flowing in the water supply conduit, a first concentration detector provided on the upper surface of the water supply conduit and a lower surface of the sludge conduit. A second concentration detector provided, a flow meter provided in the water supply conduit, a calculator for obtaining the difference between the concentration detection signals detected by the first and second concentration detectors, and from this calculator And a control circuit for outputting a pump drive control signal in accordance with the flow rate signal sent from the flowmeter and the sludge mixture in the water supply conduits having different cross-sectional areas obtained from the first or second concentration detector. Sludge mixed water arrival indicating the position when water arrives Flow rate control, which comprises a position signal and a selection circuit for selecting a pump drive control signal according to the cross-sectional area of the water supply line based on a flow rate change signal indicating a change in flow rate sent from the flow meter. apparatus.