JPH07295654A - Water level control system for plural branch type reservoirs - Google Patents

Abstract

PURPOSE:To provide the water level control system which holds the water levels of downstream reservoirs, which branch from the same upstream reservoir and are connected in water processing facilities, etc., within a proper range only by measuring the water levels without directly measuring the passing water flow rates of the respective reservoirs. CONSTITUTION:This system is provided with a control system 10 which starts the control operation of the water level control system at a certain-time period, and each downstream reservoir is provided with a level meter 4, a control valve 7, and a control valve controller 6 which inputs the measured value of the level meter each time a control system clock sends a reference period signal and calculates the manipulated variable of the control valve to control the valve, and further each upstream reservoir is provided with a water distribution pump 2 which sends out processed water, a water distribution flowmeter 8 which measures the amount of sent water, and a water distribution pump controller 9 which inputs the measured values of the level meters of the downstream reservoirs and the measured values of the water distribution flowmeters each time the control system clock sends the reference period signal, finds the flow rate of the water send by the water distribution pump by calculation, and controls the water discharge rate of the said water distribution pump so that the flow rate is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment facility such as a water purification plant, which has a pond tank located upstream, such as a sand basin, and a plurality of ponds into which the treated water from the upstream pond tank branches. TECHNICAL FIELD The present invention relates to a water level control system in a plurality of downstream pond tanks connected to the same upstream pond tank such as a filtration pond.

[0002]

2. Description of the Related Art A conventional control system for controlling water levels in an upstream pond and a plurality of ponds connected downstream thereof will be described with reference to FIG. In FIG. 2, reference numeral 1 denotes an upstream pond tank, and the treated water in the pond tank 1 is sent by a water distribution pump 2 to a plurality of downstream pond tanks 31 to 3n for performing the next treatment.

From the pond tanks 31 to 3n on the downstream side, the treated water having a flow rate according to the load on the further downstream side is sent out.
It is necessary to keep the water level in the pond tanks 31 to 3n within a certain range to maintain proper treatment. To keep the water level of the pond tanks 31 to 3n constant, each pond tank is provided with a level meter 41 to 4n for measuring the water level, a flow control valve 71 to 7n and a valve controller 61 to 6n. The valve controllers 61 to 6n adjust the flow rate of the inflow water into each pond tank so that the output of
It is possible in principle by controlling through ~ 7n, but when there is load fluctuation in a large tank with large inertia such as a water purification plant, it is difficult to maintain an appropriate water level by controlling only the output signal of the level meter. May become. Therefore, in the conventional water level control system, the downstream pond tank 31
Flowmeters 51 to 5n are installed on the treated water delivery side of ~ 3n, and valve controllers 61 to 6n for each pond tank are level meters 41 to 4n and flowmeters.
Based on the measured values of both 51 to 5n, the operation amount of the flow control valves 71 to 72 is calculated, and the water level of each pond tank is controlled to be maintained at a constant value.

[0004]

The water level in a plurality of downstream pond tanks into which the treated water sent from the upstream pond tank is branched and flows into a predetermined range in order to maintain the stability of the treatment. It needs to be kept but need not be at a strictly constant water level. In addition, it is usually sufficient to grasp the approximate value of the flow rate sent out from the downstream pond tank which serves as a control input signal for keeping the water level within a predetermined range.

In the present invention, the water level of a downstream pond tank branched from the same upstream pond tank in a water treatment facility,
The objective is to realize proper control of the water level with a simple system that keeps it within an appropriate range only by measuring the water level without directly measuring the flow rate of water passing through each pond tank.

[0006]

[Means for Solving the Problems] A water level control system for controlling the water level of each of a plurality of downstream pond tanks branched and connected from an upstream pond tank is provided with a control system clock for activating the control operation of the control system at a constant time period. A level meter for water level measurement, a control valve for adjusting the amount of inflow water, and a control valve for taking in the measured value of the level meter each time the control system clock sends the reference period signal to each of the downstream pond tanks. And a control valve controller for calculating and controlling the manipulated variable.

In the pond tank on the upstream side, a water distribution pump for sending the treated water to the pond tank on the downstream side, a water flow meter for measuring the amount of water to be sent, and the control system clock as a reference period signal. Each time you send out, the measured value of the level meter installed in each downstream pond tank and the measured value of the distribution flow meter are taken in and the value of the flow rate delivered by the water distribution pump is calculated to obtain this value. A water level control system is constructed by providing a water distribution pump controller for controlling the discharge water amount of the water distribution pump.

[0008]

[Operation] For each activation signal transmitted by the control system clock, measurement data is taken in to the control valve controller and the water distribution pump controller, and a calculation for a control operation amount based on the taken measurement data is executed to execute the control valve and water distribution. The pump is controlled.

[0009]

[Example] The water level of a plurality of pond tanks connected to one pond tank,
FIG. 1 shows a control system of one embodiment for controlling using the control method of the present invention, and the present invention will be described with reference to this drawing. In addition, in FIG. 1, FIG.
Since the elements having the same functions as those in 1 are denoted by the same reference numerals, the description thereof will be omitted.

In FIG. 1, the treated water in the pond tank 1 on the upstream side is supplied by the pump 2 to the pond tanks 31 to 3n on the downstream side. It is measured as a collective flow rate by the flow meter 8 provided in the delivery side water distribution channel. The amount of water flowing into each of the downstream pond tanks 31 to 3n is adjusted by control valves 71 to 72 provided for each pond tank, and each control valve 71 to 7n is a level meter 41 to 4n provided in each pond tank. Are controlled by the valve controllers 61 to 6n that receive the output signal of

The level measurement output signals of the level meters 41 to 4n are supplied to the upstream pond tank 1 at the same time as the above valve controllers 61 to 6n.
It is also input to the water distribution controller 9 that controls the discharge flow rate of the pump 2 that sends the treated water. The flow path of the water distribution pump 2 is provided with a water flow meter 8 for measuring the amount of water sent by the water pump 2. The measured output signal of the water flow meter 8 is measured by the level meters 61 to 6n. It is also input to the flow rate controller 9 along with the output signal.

The valve controllers 61 to 6n and the water distribution pump controller 9 are provided with a reference time signal of the control system clock 10 which gives a reference time signal at a constant time interval ΔT.
Read the measured value of each level meter 41 to 4n and distribution water flow meter 8,
The water distribution pump and the control valves 71 to 7n are operated based on the result of the arithmetic processing using the read data. The time interval ΔT that determines the above-mentioned control cycle is selected and set such that the control result can be detected as a change in the measurement output of the level meters 41 to 4n.

As described above, since the measurement and arithmetic processing are executed with a constant time interval ΔT as a cycle, the operation set values of the control valves 71 to 7n and the water distribution pump 2 are also constantly operated at the same time interval ΔT. It is modified step by step in units of quantity. Next, system variables at a certain time t given by the control system clock 10 in FIG. 1 are defined as follows, and the valve controllers 61 to 6n and the water distribution pump controller 9 are defined.
The control amount of is explained.

Qt; Water flow rate of water distribution pump 2 = Measured value of flow meter 8 Lit: Water level of No. i pond tank = Measured value of No. i level meter Lio; Target water level of No. i pond tank ΔL; Allowable range of water level control Zit: No. i pond tank control valve opening ΔZ; Control valve opening operation unit Si; Horizontal pond area of No. i pond tank ΔT; Time period of control system clock Each valve controller 61-6n has level meter 41-4n Measured value L
Compared with it for each target water level Lio, the opening of the control valves 71 to 7n in the next cycle t + 1 at time t is
Operate so that the value is equivalent to the following expression (1) or expression (2).

If Lio-Lit> + ΔL

[0016]

## EQU1 ## Zit + 1 = Zit + ΔZ (1) If Lio−Lit <−ΔL

[0017]

## EQU00002 ## Zit + 1 = Zit-.DELTA.Z (2) Further, in the water distribution pump controller 9, by the measured value Lit of each level meter 41 to 4n and the measured value Qt of the water distribution flow meter 8, the next time t is calculated. The following formula (3) for calculating the water supply amount of the water distribution pump 2 in the cycle t + 1 is calculated, and the discharge amount of the water distribution pump 2 is manipulated so that the calculated water supply amount Qt + 1 is obtained.

[0018]

## EQU00003 ## Qt + 1 = Qn + .SIGMA.Si (Lio-Lit) /. DELTA.T (3) As described above, in the method of the present invention, the inflow water amount to each pond tank on the downstream side is measured by the level meter provided in each pond tank. Is controlled so that the measured value becomes a predetermined value, and the delivery flow rate of the water distribution pump is controlled so that the delivery flow rate of the treated water from the upstream pond tank matches the water level of each downstream pond tank.

[0019]

According to the water level collective control method of the present invention, the delivery flow rate of the treated water delivered from the upstream pond tank is controlled based on the water level measurement result of the level meter provided in the downstream pond tank. The water level in each downstream pond tank is controlled stepwise by a constant operation amount as a unit only by the measurement output of the level meter with a time interval at which the control result can be detected. There is no need to provide a flow meter for controlling the water level by measuring the treated water flow rate passing through the pond tank, and the effect that the water level can be properly maintained by the control system with a simple configuration can be obtained. It is convenient to apply to the water level control of existing facilities that do not have a flow meter for each tank.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a water level collective control system according to the present invention.

FIG. 2 is a block diagram of a water level control system according to a conventional technique.

[Explanation of symbols]

 1 upstream pond tank 2 water distribution pump 31,3n downstream pond tank 41,4n level meter 51,5n delivery flow meter 61,6n valve controller 71,7n control valve 8 water distribution flow meter 9 water distribution pump controller 10 control system clock

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G05B 19/05 G05D 7/06 AB

Claims (1)

[Claims] 1. A water level control system for adjusting the water level of each of a plurality of pond tanks on the downstream side connected to the same pond tank on the upstream side, wherein a control system clock for activating a control operation of the control system at a constant time cycle is provided. In each of the pond tanks on the downstream side, a level meter for measuring the water level, a control valve for adjusting the amount of inflow water, and each time the control system clock sends a reference period signal, the measured value of the level meter is taken in and adjusted. A control valve controller that calculates and controls the operation amount of the valve is provided, and a distribution pump that delivers the treated water to the upstream pond tank and the distribution pump that measures the amount of water that is sent to the downstream pond tank. A distribution flow meter to perform, and each time the control system clock transmits a reference period signal, the measurement values of the level meter and the distribution flow meter provided in each of the downstream pond tanks are taken in and the A water level of a branch type multiple pond tank characterized in that a water pump sends a value of a flow rate by calculation, and a distribution pump controller for controlling the discharge water amount of the water distribution pump is provided so as to obtain the value of the flow rate. Bulk control system.