JPS6123223A - Terminal pressure controller - Google Patents

Abstract

PURPOSE:To secure an equal level of fed pressure between the high and low ground level sides with a simple constitution and a simple operation, by keeping a fixed level for a pressure gauge set at the pump discharge side by means of a control valve and deciding the pump discharge pressure from the fixed value of the pressure gauge. CONSTITUTION:A pump discharge valve 3 is provided at the discharge side of a pump 2, and the pipeline at the pump discharge side is branched to the high and low ground level sides 4a and 4b. The tap water is supplied via the supply valves 9 and 10 at the high and low ground level sides respectively. A pressure gauge 19 is set at a place where the pipelines join at the discharge side of the pump 2; while a pressure control valve 8 of the low ground level side and a pressure gauge 7 are provided to the supply pipeline at the low ground level side. The signals of both gauges 19 and 7 are supplied to a terminal pressure controller 18, and the target pressure value 17a of the low ground level is delivered to a pressure control part 13 from an arithmetic part 17 of the controller 18. Then the value 17a is collated with the pressure signal 7a of the gauge 7, and a pressure deviation signal 13a is delivered to the valve 8. The opening amount of the valve 8. The opening amount of the valve 8 is controlled to obtain the coincidence between the signal 7a and the value 17a. The part 17 delivers the target water pressure value 17b also to a pressure control part 16. The water pressure deviation signal 16a is delivered to a pressure distributing part 15 to obtain the coincidence between the value 17b and the feed pipeline pressure signal 19a of the gauge 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a terminal pressure control device that supplies water at the same pressure to consumers having different head heights.

[Technical background of the invention and its problems]

For example, in a 71 general purpose water facility, water may be supplied to locations with different lift heights using a plurality of water pumps. In any case, if the water supply pressure is not controlled, a large amount of water will be supplied to the low head side and a small amount of water will be supplied to the high and coarse side, resulting in a significant imbalance.

Conventionally, in order to keep the water supply pressure constant on the highland side and the lowland side, water was pumped up from the pump suction tank using a lift pump, and the discharge side was pumped with 1. There is a lift pump discharge valve and its piping is combined and branched to the upland side and the lowland side with supply piping. That is, the highland side.

After branching off to the lowland side, a flow needle, pressure needle, lowland side pressure regulating valve, and highland side pressure regulating valve are installed on each side.

The flow rate signals and pressure signals from the flow meter and the pressure needle are input to the control device, and the control device converts these signals into, for example, digital data to equalize the water supply pressures on the highland side and the lowland side using a predetermined calculation formula. The opening degrees of the lowland side pressure regulating valve and the highland side pressure regulating valve are adjusted. However, such a control method requires two sets each of a low-altitude pressure regulating valve, a high-altitude pressure regulating valve, a flow meter, and a pressure gauge, and the control device performs complex calculations, making the configuration complex and requiring maintenance. It's not easy and it's expensive when something goes wrong.

[Purpose of the invention]

The present invention is intended to eliminate the above-mentioned problems, and has a simple configuration,
It is an object of the present invention to provide a terminal pressure control device which can equalize the feeding pressures on the highland side and the lowland side with simple calculations and is inexpensive to construct.

[Summary of the invention]

The present invention relates to a pressure gauge that obtains the pressure on the discharge side of a plurality of lift pumps in a system that supplies fluid to customers with different lift heights using a plurality of lift pumps, and a highland area with high resistance in a pipe connected to the outlet side of the pressure gauge. With side discharge pipe.

A low-lying discharge pipe with low pipe resistance, and a regulating valve and pressure gauge installed on this low-lying discharge side are installed, and the regulating valve maintains the value of this pressure gauge at a constant value, and the low-lying pipe is lower than the fixed value. Calculate the pipe resistance, add the lift on the highland side to the resistance on the lowland side, use the added value as the target value of the pressure gauge, and control the number and rotation speed of the pumps so that the value on the pressure gauge becomes the target value. This is a terminal pressure control device characterized by:

(Embodiments of the Invention) Next, the present invention will be described in detail. Fig. 1 shows a pump 2 connected in parallel to pump water to areas on the highland side and lowland side, each having a different required head. a pump discharge valve 3 and a pump discharge valve 3 connected in series to each other.
A supply pipe 4 that joins the discharge sides of the water and sends water, a low-pressure side pressure regulating valve 8 that adjusts the water supply pressure on the low-lying side branched from the supply pipe 4, and a low-pressure side pressure regulating valve 8 adjusted by the low-pressure side pressure regulating valve 8. A pressure gauge 7 that measures the water supply pressure, a lowland side supply valve 10 that distributes and supplies water whose pressure has been adjusted by the low pressure side pressure regulating valve 8 to the lowland side, and a water pump side of the low pressure side pressure regulating valve 8. In a terminal pressure control device consisting of a highland side supply valve 9 that distributes and supplies water to the highland side that has been branched and taken out, a pressure gauge 1 measures the water supply pressure in the supply piping section.
9, and a pressure control unit 13 that detects a pressure signal 7a from the pressure gauge 7 and a deviation from a preset pressure target value 17a and outputs a pressure deviation signal 13a to the low pressure side pressure regulating valve 8.

A rotation speed control unit 12 that detects a deviation from a rotation speed 20a output from a rotation speed meter 20 attached to the lift pump 2 and a rotation speed target value 14a set in advance and outputs a rotation speed deviation signal 12a to the lift pump 2. and a calculation unit 17 that outputs a pressure target value 17a and a water supply pressure target value 17b from the flow rate-head characteristics of the water pump 2 and pipe resistance characteristics of the supply pipe 4 that have been input in advance, and a water supply pressure target from the calculation unit 17. a pressure control section 16 that outputs a water supply pressure deviation signal 16a based on the value 17b and a supply piping pressure signal 19a from the pressure gauge 19; and a water supply pressure deviation signal 16a from the pressure control section 16.
and a pressure distribution unit 15 that outputs a pressure distribution value 15a from the flow rate-head characteristic of the lift pump 2 that has been set in advance, and a rotation speed deviation signal 14 that outputs the pressure distribution value 15a from the pressure distribution unit 15.
2 shows a terminal pressure control device comprising a pressure-to-rotation speed converter 14 for converting the pressure to the rotational speed.

1 is a pump suction tank, from which water is sucked up by three water pumps 2. A pump discharge valve 36 is provided on the discharge side of the pump 2, and its discharge side piping is merged and goes near the consumer, and is branched into a highland side 4a and a lowland side 4b, and is connected to a highland side supply valve 9 and a lowland side. Supply valve 1
Water is supplied through 0.

In addition, a pressure gauge 19 is installed at the place where the pipes meet on the discharge side of the pump 2, and a low-land pressure regulating valve 8 is installed in the low-land supply pipe. and a pressure gauge 7. and pressure gauge 1
9 and pressure gauge 7 are input to a terminal pressure controller 18. The terminal pressure control device 18 includes a calculation section 17, and the calculation section 17 outputs the lowland side pressure target value 17a to the pressure control section 13, and the pressure control section 13 outputs the lowland side pressure target value 17a from the calculation section 17 and the pressure. A total of 7 pressure signals 7a are compared, and the pressure deviation signal 13a is outputted to the lowland side pressure regulating valve 8, and the pressure signal 7a of the pressure gauge 7 is adjusted to the lowland side so that the pressure signal 7a is equal to the pressure target value 17a from the calculation unit 17. Adjust the opening degree of the regulating valve 8.

The calculation unit 17 also outputs the water supply pressure target value 17b to the pressure control unit 16, and the pressure control unit 16 receives the supply pipe pressure signal 19a of the pressure gauge 19, and the target value 17b and the supply pipe pressure signal 19a of the pressure gauge 19 are inputted to the pressure control unit 16. The water supply pressure deviation signal 16a is output to the pressure distribution unit 15 so that the pipe pressure signal 19a matches. The pressure distribution unit 15 determines the number of operating pumps 2 based on the deviation signal 16a, calculates the pressure distribution of each pump 2 based on the number of operating pumps, and calculates the pressure distribution value 15a as pressure -
It is output to the rotation speed converter 14. Pressure-rotation speed converter 14
Then, the distributed pressure signal is converted into the rotation speed of each lift pump and outputted to the rotation speed control section 12 in the lift pump 2 as the rotation speed target value 14a.

The rotation speed 20a of the rotation speed meter 20 is input to the rotation speed control section 12, and the rotation speed deviation signal 12a is inputted to the rotation speed control section 12 so that the rotation speed 20a of the rotation speed counter 20 becomes the rotation speed target value 14a. is outputted to each pump to control the rotational speed of the pump 2.

The present invention will be described in detail below with reference to the graph shown in FIG. In Fig. 2, the horizontal axis represents the discharge tl (
Q), pressure (P) and lift α force are shown on the vertical axis. Now, the Q-H characteristic of one of the pumps 2 is expressed as a curve (Q-H
), 1, and Q- when two of the water pumps 2 are in operation.
Assuming that the H characteristic is a curve (Q-H), 2, the current operating point when one pump 2 is operated is the composite curve (R1+R2) of the lowland side pipe resistance R1 and the highland side pipe resistance R2. The curve (Q-H) when there is one water pump, becomes point A with □.

At this time, if the pressure value of pressure gauge 2 is pressure P2, pressure P
2 is the sum of the combined pressure H2 of the actual head and terminal pressure and the high altitude piping resistance azQz, and is expressed by the following equation (1).

P 1 = Hi 10a2 Q2 - (1) Also, if the value of the pressure gauge 7 is pressure P1, the pressure P1 is the outlet pressure of the lowland side pressure regulating valve 8, that is, the combined pressure of the actual head to the lowland side consumer and the terminal pressure. The sum of H1 and low-lying piping resistance atQτ is expressed by the point A' and the following equation (2).

PH=l(1+a, Ql Also, in the $2 figure, the curve (Q-H) is the lowland side pressure regulating valve 8
Q-H characteristic, R3 is the piping resistance after the control valve.

Therefore, the pressure difference (P2Pl) between the pressure P2 of the pressure gauge 19 and the pressure P1 of the pressure gauge 7 is a pressure loss occurring before and after the lowland side pressure regulating valve 8.

Then, when the consumer opens the high-altitude side supply valve 9 with the operating point of one of the pumps 2 at point A, the high-altitude side pipe resistance decreases and changes from resistance R2 to resistance fL2', resulting in a pipe line piping composite curve. moves to the curve (R1+R2X curve (R1+RS)), and the pump 2 operating point also moves to point B.

In this case, the pressure P of the pressure gauge 19 is expressed by equation (3).

= horse+a*Qs'... (3) However, azQ2 is the highland side piping resistance when the highland side supply valve 11 is opened, that is, the pressure value of the pressure gauge 19 is the highland side supply valve 11.
Pressure (afi Qt R2Q:'
) decreases by

In addition, the pressure P of the pressure gauge 7 is the discharge tqt on the highland side and the discharge m
Q-H of the lowland side pressure regulating valve 8 to shift to Q'.
The characteristic curve (Q-H) is also reduced by the curve (Q-H) &l and is expressed by point B' and equation (4).

P'1=HH+ a HQ'+ '...(4) However, p atQ? is the lowland side piping resistance when the highland side is open,
That is, the value on the pressure gauge 7 decreases by the pressure (81Q; 'a1Q';') by opening the highland side supply valve ]1.

Since the pressures H, Ht are fixed values according to equations (1) to (4), if atqW = aiQt from FIG. 2, the pressure on the lowland side and the pressure on the highland side become equal.

If the value on pressure gauge 7 has now fallen to pressure P/, then pressure PI
is P; =H2+ a IQr = Ht + at Q
: At the same time, the value of pressure gauge 7 is also PH=H1+ a, Q
At τ, the lever atQW=atQ, and the pressure on the highland side and the pressure on the lowland side become equal.

Therefore, the pressure gauge 7 is adjusted so that the value of the pressure gauge 7 becomes a certain target value.
control the value of Now, suppose that the target value of pressure gauge 7 is set to pressure P1.
Then, Pl=H, +aIQ7 and a, Q: = P, -H
, find the pressure asqr, and calculate the value of pressure gauge 19 as Hl + a
If the pressure is controlled so that I Q';

In the calculation unit 17, the maintenance personnel sets the pressure P, and outputs the value of the pressure P to the pressure control unit 13.
3, the pressure gauge 7 is controlled so that the value becomes the pressure P.

Further, the calculation unit 17 calculates the pressure *atq: from the pressure P1.

Pressure axQ': Calculate pressure P and control so that the value of pressure gauge 19 becomes pressure P.

In Fig. 3, the value of the pressure gauge 19 has fallen to pj = H1 + alql, so the pressure P is calculated by P '' Hl + 711 Q?, and since the deviation of the pressure (P pt) is large, a second pump is installed in the water pump 2. When the operation command is issued, the operating point of the lift pump 2 at that time is determined by the Q-H characteristic curve of the two lift pumps 2 (combined Q-aLz, high-altitude side piping resistance R2', and low-altitude side piping resistance R1). is the intersection point C of the curve (几1+R2').At this time, the pressure P of the pressure gauge 19 is P r = Hl
+ a I Q'l ' ・” (5) However, t
atQ"x is the highland side pipe resistance when two pumps are operated. Also, the value of the pressure gauge 7 is the Q - of the lowland side regulating valve 8 because the discharge amount on the highland side shifts from the flow rate to the flow rate Ql. H
The characteristic also shifts from the curve (Q-H)TI' to the curve (q-n),', thereby acting on point C. At this time, the pressure P,' indicated by the pressure gauge 7 becomes P,.=H, "10atQW".

In the terminal pressure control device of the present invention, the value of the pressure gauge 19 PH=
)(, + a, Q”+ == P.

The value of the pressure gauge 19 is controlled so that P2=H2+a, Ql=P, so in the case of Fig. 2, a+Qt=a
Since +Q':''+ asQ'5=at Q:'' is not true, move the lowland side pressure regulating valve 8 in the closing direction, move the lowland side piping resistance curve R1 to curve R(, and set the value of the pressure gauge 19 as a point. It can be seen that the value on the pressure gauge 7 also becomes point A' as the pressure is moved to the point A'.

Therefore, it can be seen that according to the control method of the present invention, the pressure on the lowland side and the pressure on the highland side are easily equalized.

Further, the value of pressure P is used to determine the number and rotation speed of each water pump 2.

Note that even if the rotation speed is changed, the Q-H characteristic of the water pump 2 behaves in the same way as when the number of water pumps 2 is changed.

Therefore, according to the above embodiment, by optimizing the low area side pressure setting value Pa and the pressures H1 and H2, the low area side pressure can be adjusted based on the calculation results with a simple calculation to keep the low area side pressure constant. By controlling the opening degree of the valve 8, as well as determining the number of water pumps 2 and controlling the rotation speed, it is possible to accurately control the terminal pressure.

Therefore, the configuration is simple and the cost is low without using a complicated control device, computer, or expensive flow rate detector.

Although the present invention has been described in the above embodiments for controlling fluid, it is not limited to this and can also be applied to, for example, controlling gas.

〔Effect of the invention〕

As described above, the present invention supplies fluid from each discharge pipe to consumers with different pump heights via pressure gauges on the discharge side of a plurality of water pumps, and provides a regulating valve in the discharge pipe with low pipe resistance. At the same time, a pressure gauge is installed on the outlet side, and the value of this pressure gauge is kept at a constant value by a regulating valve.The discharge pressure of the pump is determined by the head of each customer based on this constant value, and the number of pumps and the rotation speed are controlled. By doing so, it is possible to provide a terminal pressure control device that can accurately control the supply pressure at each customer to equalize it with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a terminal pressure control device showing one embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the operation of FIG. 1. 1... Pump suction tank, 2... Lifting pump 3.
... Lifting pump discharge valve, 4 ... Supply piping 5 ... Control device, 6 ... Flow meter 7 ... Pressure gauge,
8...Lowland side pressure supply valve 9...Highland side supply valve 10...Lowland side supply valve 11...Highland side pressure regulating valve 12...Rotation speed control section 13...Pressure control Part 1
4...Pressure-speed converter" 5...Pressure distribution part, 1
6... Pressure control section 17... Calculation section,
18... Terminal pressure control device 19... Pressure gauges 2, 20
...Revolution counter agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1

Claims (1)

[Claims] Lifting pumps connected in parallel to pump water to highland and lowland areas with different required lifting heads, lifting pump discharge valves connected in series to each of these pumps, and these pump discharge valves. A supply pipe that joins the discharge side and sends water, a low-pressure side pressure regulation valve that branches off from this supply pipe and adjusts the water supply pressure on the lowland side, and a water supply pressure on the lowland side that is adjusted by this low-pressure side pressure regulation valve. First thing to measure
a pressure gauge, and a lowland side supply valve that distributes and supplies water whose pressure is regulated by the low pressure side pressure regulating valve to the lowland side;
In a terminal pressure control device comprising a highland side supply valve that branches off from the water pump side of the low pressure side pressure regulating valve and supplies water to the highland side taken out in a distributed manner, the water supply pressure of the supply piping section is controlled. a second pressure gauge to measure; a pressure control unit that detects a deviation from the pressure signal from the first pressure gauge and a preset pressure target value and outputs a pressure deviation signal to the low pressure side pressure regulating valve; , a rotation speed control unit that detects a deviation from the rotation speed output from a rotation speed meter attached to the lift pump and a rotation speed target value set in advance and outputs a rotation speed deviation signal to the lift pump; a calculation unit that outputs the pressure target value and the water supply pressure target value from the flow rate-head characteristic of the water pump and the piping resistance characteristic of the supply piping;
a pressure control unit that outputs a water supply pressure deviation signal based on the supply piping pressure signal from the pressure gauge; and a pressure distribution value based on the water supply pressure deviation signal from the pressure control unit and the preset flow rate-head characteristic of the water pump. A terminal pressure control device comprising: a pressure distribution section that outputs a pressure distribution value; and a pressure-speed conversion section that converts a pressure distribution value from the pressure distribution section into the rotation speed deviation signal.