JPS588002B2 - Terminal pressure control method for wide area pipe water distribution equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a terminal pressure control system in wide area pipe water distribution equipment.

When distributing water over a wide area using pipes, it is necessary to properly pressurize the water at the water supply source so that sufficient water supply pressure can always be obtained at any end.

The amount of pressurization required will vary depending on the demand for water at each end, but when pumping water, it is undesirable from an energy-saving perspective to constantly pressurize the water at a pressure high enough to meet any demand. Therefore, water is delivered at a pressure appropriate to the demand situation.

Since the demand situation changes from moment to moment, pressure control must be performed dynamically.

One conventional pressure control method is to measure the original flow rate of water, find the required water supply pressure from the Q-H curve, and set it in the pump's discharge pressure control device. Since it is a control, it is not possible to finely control the terminal pressure.

Other conventional methods include empirically determining the appropriate pressure value based on the demand situation and setting it in the pump discharge pressure control device, and measuring pressure at typical branch points in the water distribution network. There are methods to control the pump discharge pressure based on the value, but none of them allow fine control of the terminal pressure.

Therefore, in the conventional system, depending on the demand situation, water may be cut off at the end where the conditions are poor.

In order to finely control the terminal pressure, it is possible to arrange a pressure detector at each terminal and control the pump pressure based on the signal indicating the worst condition among the signals from each pressure detector. This has not been realized because it is not economically viable.

An object of the present invention is to provide a terminal pressure control system for wide-area pipe water distribution equipment that allows fine control of terminal pressure economically.

The present invention calculates the water supply source pressure for each terminal to maintain a predetermined water supply pressure at each terminal based on the water supply flow rate at each terminal, and adjusts the discharge pressure of the water supply source pump according to the largest one of them. It was designed to be controlled.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a conceptual diagram of a wide area pipe water distribution facility to which the present invention is applied.

In FIG. 1, LIN is a water distribution pipe through which water taken from the main line ML is pressurized by a pump P and sent.

The discharge pressure of the pump P is controlled by a discharge pressure controller PC.

A set value of the discharge pressure is given to the discharge pressure regulator PC by the calculator CAL.

1, 2, . . . 6 are water supply points branched from the water distribution pipe LIN, each of which is equipped with a flow meter.

The output signal of each flowmeter is transmitted to the calculator CAL.

Details of the computing unit CAL are shown in FIG. 2 together with the connections to the water supply points 1 to 6 and the discharge pressure regulator PC.

In Fig. 2, the calculator CAL uses the measured flow rate transmitted from each water supply point and constants determined by the structure of the pipe water distribution equipment to determine the water supply point for each water supply point using a calculation formula as exemplified later. Calculate the pump discharge pressure sufficient to supply water at a predetermined end pressure at give.

Such arithmetic unit CAL can be easily constructed using a microcomputer or the like.

Now, there are several known formulas that give the pressure loss △H in a pipe of diameter D and length L when water flows at a flow rate of Q in a pipe. For example, the following Hazen-Williams formula There is a calculation formula.

△H=IC)666C-"・85・ga・87・Q1・8
5.L(1) However, C is a constant.

In this equation, D and L are constants determined by the structure of the pipe, so △H=kQ”・85
It can be expressed as (2).

However, k=1 0.666C'''・85・D4・87・
It is L.

Therefore, at the end of the pipe, water with a flow rate of Q is supplied to a predetermined pressure of Pm.
In order to supply water without dropping below in, the pressure at the water supply source must be
.

must satisfy the following condition.

Po〉△H−△h10Pmin. (3)
However, Δh is the head difference between the water supply source and the end.

Therefore, at the water supply source, it is sufficient to supply water at a pressure that satisfies the condition of equation (3).

Therefore, by applying the conditions of equation (3) to each of the water supply points 1 to 6 in FIG. 1, the pressure conditions at the water supply source corresponding to each of the water supply points 1 to 6 can be determined.

That is, However, h.

-h5 is the altitude of each point. The pressure at the water supply source is (4) ~ (
7) Since all the conditions of the formula must be satisfied, the maximum value among the values calculated by the above formula corresponds to 5.

The calculator CAL calculates the set value of the discharge pressure of the pump P by performing calculations using equations (4) to (7) and selecting the maximum value of the calculation results.

In formulas (4) to (7), when Pmin1 to Pmin5 are constant values that are almost equal to each other regardless of the water supply flow rate at each water supply point, and there is almost no difference in elevation between the water supply points, (
Since the value of equation (7) is always the maximum value, it is sufficient to always set the value of equation (7) as the set value of the discharge pressure.

However, in general, this cannot be said; especially when the pressure loss in the branch pipes from the water distribution pipe LIN to each water supply point cannot be ignored, Pmin1 to Pmin5 change depending on the water supply flow rate, so depending on the demand situation ( 4)～(
7) Any value of the expression can be the maximum value.

In such a case, apply the above (υ formula) to find the pressure loss for each branch pipe, and add it to the effective water supply pressure Pe at each water supply point, that is, the value of the following formula (4) ~ ( 7)
Calculation can be performed by substituting Pmin1 to Pmin5 in the formula.

P=1=KiQi”85+Pei (s
) In this way, the present invention calculates the water supply source pressure for each terminal to maintain a predetermined water supply pressure at each terminal based on the water supply flow rate at each terminal, and adjusts the water supply source pump according to the maximum value. The discharge pressure was controlled.

Therefore, fine end pressure control can be performed with an economical configuration in which no pressure detector is installed at each end.

However, each terminal needs to have a flow meter to measure the water supply flow rate, but since each terminal is usually equipped with a flow meter for the purpose of monitoring and recording the water supply amount, this actually makes it less economical. It won't be a loss.

[Brief explanation of the drawing]

FIG. 1 is a conceptual configuration diagram of a wide area pipe water distribution facility to which the present invention is applied, and FIG. 2 is a control system diagram in FIG. 1. ML...Water main line, LIN...Water distribution pipe, P...
- Pump, PC...discharge pressure regulator, CAL...computer, 1-6...water supply point.

Claims (1)

[Claims] 1 Based on the water supply flow rate at each end, calculate the water supply source pressure for each end to maintain a predetermined water supply pressure at each end, and control the discharge pressure of the water supply pump according to the maximum of these calculated values. An end pressure control method for wide-area pipe water distribution equipment.