JPS5952447B2 - pump control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump control device, and is particularly applicable to controlling the flow rate of a settling basin in a water treatment plant such as a sewage treatment plant or a pump station.

Conventionally, for example, in a sewage treatment plant, as shown in Figure 1,
The sewage flowing from the inflow conduit 1 as treated water is transferred to the settling basin 2.
The sand mixed in the sewage is allowed to flow slowly, and the sewage treated as treated water is led to a pump well 3 installed downstream of the settling basin 2, and is then discharged by a discharge pump 4. It is designed to be pumped up and discharged. Here, the motor 5 that drives the discharge pump 4 is controlled by the control device 6 to maintain the water level reference value L.

and the measured value L of the water level gauge 7 of the pump well 3, and is driven at a rotational speed according to the deviation, thus bringing the water level of the pump well 3 to the water level reference value L. The water level is maintained at a constant level corresponding to . By the way, the first of such configurations
In the conventional pump control device shown in the figure, control is performed to maintain the pump well 3 at a constant water level. Since the flow rate pumped out from the pump well 3 by the pump 4 also increases, the flow rate of the sewage flowing through the settling basin 2 eventually becomes faster.

In such a case, the sand in the sewage water will flow into the pump well 3 and accumulate without being sufficiently settled, which may eventually cause trouble in subsequent treatment or shorten the life of the pump. On the other hand, as shown in Fig. 3,
If the flow rate of sewage flowing in from the well 3 is small, the flow rate pumped out from the pump well 3 by the pump 4 will also be small, and the flow rate of the sewage flowing through the settling basin 2 will become too slow.

In this case, although the sand in the sewage is sufficiently precipitated, there arises the disadvantage that organic pollutants are also precipitated together with the sand. In consideration of the above points, in the present invention, the flow velocity of the settling tank is kept constant so that the sand in the water to be treated is sufficiently settled in the settling tank, and other substances (such as organic pollutants) are not allowed to settle. The objective is to measure the water level at the inlet side of the settling basin 2 and the water level at the outlet side, and by keeping the difference constant, the flow rate of the settling basin can be adjusted. is controlled at a constant level, thus allowing the sand settling basin 2 to work effectively.

An example of the present invention will be described in detail below with reference to FIG. 4, in which parts corresponding to those in FIG. A second water level gauge 22 is provided at a position on the side of the pump well 3, and outputs W1 and W2 of both water level gauges 21 and 22 are input to a subtracter 23.

The output of the subtractor 23 means the water level difference (W1-W2) between the inlet and outlet of the sand settling basin 2, and this output is used as the water level difference reference value W.

is given to the control device 24 given. Thus motor 5
Therefore, the discharge flow rate of the pump 4 is determined by the water level difference (W1-
W2), the water level difference reference value W. The water level difference is controlled to be equivalent to . In the configuration shown in FIG. 4, the flow rate of sewage in the settling basin 2 is proportional to the water level difference between the inlet and outlet of the settling basin 2, so by keeping this water level difference constant, the flow rate can be maintained at a constant value.

Therefore, if this constant water level difference (i.e., water level standard value WO) is selected as the optimal value for settling sand in sewage, the discharge of pump 4 will be adjusted accordingly even if the flow rate of sewage flowing in from inlet culvert 1 increases or decreases. Since the flow rate can be increased or decreased, only sand can be settled at all times.

As described above, according to the present invention, by controlling the discharge pump so that the flow rate in the sand settling basin is constant,
The treatment effect in the sand settling basin can be further enhanced, and in this way, treated water of good quality can be obtained for subsequent treatment, and the life of the pump can be further extended by reducing the accumulation of sand in the pump well of the discharge pump. It can be made longer.

[Brief explanation of drawings]

FIG. 1 is a route diagram showing a conventional pump control device for a water treatment plant, FIGS. 2 and 3 are route diagrams for explaining its operation, and FIG. 4 is an example of a pump control device according to the present invention. It is a route system diagram showing. 1: Inlet drain, 2: Sediment basin, 3: Pump well, 4: Discharge pump, 5: Motor, 6, 24: Control device, 7, 21, 22
: Water level gauge, 23: Subtractor.

Claims (1)

[Claims] 1. In a water treatment plant where the water to be treated flows through a settling basin to a pump well, and the treated water from this pump well is discharged by a discharge pump, the position on the inlet side and the position on the outlet side of the settling basin. A first and a second water level gauge are installed in the first and second water level gauges.
and inputting the measured output of the second water level gauge into a subtracter, and controlling the discharge flow rate of the drainage pump based on the subtraction result output to maintain the flow velocity of the sand settling basin at a constant value optimal for sand settling. A pump control device characterized by: