JPS6361802A - Feedwater controller - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a water supply control device, and particularly to a water supply control device in a variable voltage thermal power plant.

(Prior Art) Thermal power generation plans 1 to 1 in recent years are mainly thermal power generation plans 1 to 1 for transformer type intermediate loads. In such a plant, when operating in an intermediate load range, one of the multiple water supply cylinders installed in parallel, for example two, is stopped,
One water supply pump is operated to supply water. After that, when a zero load rise occurs that cannot be handled by one water pump, another water pump is turned on.

The conventional water supply control device that performs such water supply control is
As shown in the figure.

A water supply pump 5 driven by a turbine 3 for driving the water supply pump is disposed in the water supply branch pipe 1 . Further, a check valve 7, a water supply control valve 9, and a water supply control double valve 11 are sequentially arranged in the water supply branch pipe 1 on the downstream side of the water supply pump 5. These water supply control valves 9
A water supply control bypass valve 13 is connected to a bypass pipe that bypasses the water supply control multiple valve 11. The opening degrees of the water supply control valve 9, the water supply control multiple valve 11, and the water supply control bypass valve 13 are controlled by the water supply controller 15. Furthermore, this water supply controller 15 also controls the rotation speed of the water supply pump 5.

When operating the water supply pump 5 as the first pump, the water supply controller 15 first receives a water supply command and starts the water supply pump 5. As shown in FIG. 8, the water supply pump 5
When the rotation speed increases to αppm, the water supply controller 15 fully opens the water supply control multiple valve 11 as shown in the middle part of FIG. 7 (FIG. 8). Thereafter, the water supply controller 15 gradually opens the water supply control valve 9 when the water supply pump 5 reaches the minimum rotational speed αorpm. As shown in the upper part of FIG. 7, the water supply controller 15 sets the water supply pump 5 to the minimum rotation speed α. r
In the control of the low pressure/low flow rate region rotating at pm, the water supply amount is controlled by operating the water supply control valve 9.

Eventually, when the water supply pump 5 reaches an opening degree β% near full open, the water supply controller 15 operates the water supply control bypass valve 13 to fully open (FIG. 7, bottom row, FIG. 8). Thereafter, the control moves to high pressure and high flow, and the water supply controller 15 controls the water supply amount by increasing the rotation speed of the water supply pump 5 as shown in the upper part of FIG. 7 (see FIG. 8). ).

Also, when the water supply pump 5 is operated as a second pump, as shown in FIG. At the same time, the water supply controller 15 reaches the minimum rotation speed α as shown by the two-dot chain line in FIG. 8. Gradually increase the rpm above.

Next, when the water supply control valve 9 is opened, the water supply control valve opening curve 19) in the figure shows that when the water supply control valve 9 reaches the opening degree β%,
The water supply control bypass valve 13 is fully opened (water supply control bypass valve opening curve 21 in the same figure), but the water supply pump 5 is fully opened.
When operating as a metal pump, since the first pewter pump is already in operation, the pressure in the water supply main pipe 23 (Figure 16) on the upstream side of the water supply branch pipe 1, that is, the water supply pressure, is equal to the water supply pressure in the water supply branch pipe 1. Higher than the pump 5 outlet side pressure.

Reference numeral 25 in FIG. 9 indicates the water supply pressure curve, and reference numeral 27 indicates the water supply pump outlet side pressure.

Therefore, even if the water supply control valve 11 and the water supply control valve 9 are turned on, the water supply does not flow out into the water supply m pipe 23 from the water supply pump 5, which functions as a second pump, and the water supply control valve 9 and the water supply control valve 11 The opening operation is an unnecessary operation. Since the opening operation of the water supply control bypass valve 13 is avoided after performing this unnecessary operation, even if the water supply control bypass valve 13 is fully opened, as shown in FIG.
The timing for supplying water to the l pipe 23 (service-in timing) is delayed to the time point 29 when the second pewter pump needs to be turned on.

Therefore, in order to make this service-in timing coincide with the time point 29 when the second pewter pump needs to be turned on, the full opening start time of the water supply control multiple valve 11 is set by adjusting the rotation speed α rpm (α1) of the water supply pump 5.
≦α) (Figure 10).
.

However, in this case, although the delay in service-in timing is resolved, the differential pressure 30 between the water supply pressure and the water supply pump outlet side pressure becomes large at the same time when the water supply control multiple valve 11 is closed. The large differential pressure 30 will act on the check valve 7, and there is a risk that the check valve 7 will be damaged.

J3, the parts similar to those in Figure 9 in Figure 10 are the same.
without the sign.

(Problems to be solved by the invention) As shown above, the conventional water supply system tll! In the device, when the water supply pump is operated as a second pewter pump, the service-in timing may be delayed, or an excessive pressure difference 30 may act on the check valve 7, causing damage to the check valve 7.

This invention was made in consideration of the above facts,
The purpose of the present invention is to provide a water supply control device capable of optimizing the service-in timing of a water supply pump operated as a second or more pump and ensuring the soundness of a check valve on the outlet side of the water supply pump. .

[Structure of the invention]

(Means for Solving Problems) This invention provides a water supply control device for a water supply system in which a plurality of water supply pumps are installed in parallel, each of which is installed in a plurality of water supply branch pipes branched from a water supply main pipe. A water supply pump, a water supply control valve installed in each of the water supply branch pipes, a water supply control bypass valve installed in a bypass pipe that bypasses the water supply control valve, the water supply pump, the water supply control valve, and the water supply control bypass valve. is connected to the pump rotation speed and valve opening degree to 1J.
The water supply controller has a water supply controller that controls the water supply pump, and this water supply controller operates the water supply pump when the other water supply pumps are operating. In this case, the water supply bypass valve is directly opened based on the water supply pressure in the water supply gI pipe and the differential pressure between this water supply pressure and the water supply pump outlet pressure of the water supply branch pipe.

Therefore, according to the water supply control device according to the present invention, the water supply is controlled at the optimum timing without unnecessary operation of the water supply control valve when the second or more pumps whose water supply pressure is already high are turned on. The bypass valve can be operated 1 jil.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a system diagram showing an embodiment of the water supply control device according to the present invention, and FIG. 2 is an internal configuration diagram of the water supply controller shown in FIG. 1. FIG. In both of these figures and in FIGS. 3 to 5, which will be described later, the same parts as in the conventional example are designated by the same reference numerals.

The water supply system of a variable voltage intermediate load operation thermal power plant is such that a plurality of, for example, two water supply branch pipes 1 are branched from a water supply main pipe 23, and a water supply pump 5 is installed in each water supply branch pipe 1. The water supply system then uses condensate from the condenser as water supply to forcefully feed it to the high-pressure water heater. Each of the above-mentioned water supply pumps has a customer capacity capable of supplying 50% of the total amount of water supplied from the water supply system.

Each water supply branch pipe 1 has a check valve 7 on the downstream side of the water supply pump 5.
, a water supply control valve 9 and a water supply control rear valve 11 are arranged in sequence, and a water supply control bypass valve 13 is provided in a bypass pipe that bypasses the water supply control valve 9 and the water supply control rear valve 11. These water supply control valve 9, water supply control pusher 11, and water supply control bypass valve 13 are connected to a water supply controller 31, and the valve opening degree is controlled. The water supply controller 31 also includes a water supply pump driving turbine 3 that rotationally drives the water supply pump 5.
The rotation speed of the water supply pump 5 is controlled via the water supply pump driving turbine 3.

A water supply pressure gauge 33 is mounted on the water supply main pipe 23 on the downstream side of each water supply branch pipe 1 . This water supply pressure gauge 33 is connected to the water supply control 7A31 and outputs a water supply pressure signal in the water supply main pipe 23 to the water supply controller 31.

Also, the differential pressure between the internal pressure of the water supply branch pipe 1 on the downstream side of the water supply pump 5 and the upstream side of the check valve 7 and the internal pressure of the water supply main pipe 23 (hereinafter referred to as
(simply referred to as "differential pressure") is measured by the differential pressure gauge 35.

This differential pressure gauge 35 is also connected to the water supply controller 31 and outputs a differential pressure signal to the water supply controller 31.

The water supply controller 31 starts the water supply pump 5 when a water supply signal is input, as shown in the upper part of FIG. In this case, the amount of water supplied is controlled by the opening degree of the check valve 7. Also, the water supply pump 5 has the lowest rotational speed (α. r p
When controlling the high pressure/high flow rate range above the m) range, the water supply a is controlled by adjusting the rotational speed of the water supply pump 5.

Here, the minimum rotation speed α of the water supply pump 5 is. r p m 1
．． J is the rotation speed determined from the critical speed of the water supply pump driving turbine 3 and the overflow characteristics of the water supply pump 5.

In addition, as shown in the middle part of FIG.
ci or less, and the water supply pump 5 has the lowest rotational speed α. rp
When the rotation speed reaches αrpm or higher, which is slightly lower than m,
Control is performed to open the water supply control multiple valve 11. The above γ
is the maximum water supply pressure obtained at the lowest rotation speed (α.rpm) of each water supply pump 5. The fact that the water supply pressure measured by the water supply pressure gauge 33 is 9/CIi in this γ means that the other water supply pumps 5 are already in operation. Therefore, when the water supply pump 5 is operated as a second pewter pump, the water supply pump consequent 11 is not operated to close.

Furthermore, as shown in the lower part of FIG. 9, the water supply controller 31
The water supply pressure measured by the water supply pressure gauge 33 is the above-mentioned γ
To! j/cM or more, and the differential pressure gauge 35 shows 1
When the measured differential pressure is less than 9/Ci in δ,
The water supply control bypass valve 13 is controlled to be closed.

Here, δ is determined in consideration of the time required from when the water supply control bypass valve 13 starts opening until it stops, the speed increase rate of the water supply pump 5, and the upper limit rate of the water supply pressure. In other words, in FIG. 5, δ is calculated from the time point 29 when the second white water supply pump needs to be turned on when the differential pressure becomes O, to the water supply control bypass valve 1.
This is the differential pressure value at a point that went back by the time required for full opening in step 3. Therefore, if the water supply control bypass valve 13 is controlled as described above (lower part of FIG. 9), this water supply control bypass valve 1
3 is fully opened and water is supplied from the water supply pump functioning as the second pewter pump to the water supply main pipe 23 side (service-in timing), which coincides with the time point 29 when the second pewter water supply pump needs to be turned on.

Next, the effect will be explained.

First, the operation when the water supply pump 5 is operated as the first pump will be described with reference to FIG.

When a water supply command is input, the water supply control t2Il device 31 starts the water supply pump 5 via the water supply pump driving turbine 3. When the rotational speed of the water supply pump 5 gradually increases (water supply pump rotational speed curve 37 in Figure 3) and reaches αrρm, the water supply control double valve 11 is fully opened (valve opening degree curve after water supply control in the same figure). 17). The rotation speed of the water supply pump 5 further increases to the minimum rotation speed α.

When the rpm reaches that point, the water supply control valve 9 starts to be opened (water supply control valve opening degree curve 19 in the figure). After that, the water supply pump 5 is α. rpm, the water supply amount is controlled by gradually opening the water supply control valve 9.

As the water supply control valve 9 is opened, the water supply pressure in the water supply main pipe 23 gradually increases as shown by a water supply pressure increase curve 25 in the figure. When the water supply pressure reaches γKg/ci,
Fully open the water supply control bypass valve 13 (water supply control bypass valve opening curve 21 in the figure). Note that this water supply pressure is γ
The point in time when 89/ci is reached is the point in time when the opening degree of the water supply control valve 9 corresponds to the opening degree β% as in the conventional case. Thereafter, the rotation speed of the water supply pump 5 is adjusted to control the high pressure/high flow rate region.

Next, the operation when the water supply pump 5 is operated as the second pump from the intermediate load region where one water supply pump is operated will be explained with reference to FIG.

The water supply controller 31 starts the water supply pump 5 based on the second minute pump command signal. At this time, the water supply pressure in the water supply main pipe 23 measured by the water supply pressure gauge 33 is greater than γKU/ci as shown in the water supply pressure curve 27 in FIG. 4, so the water supply control multiple valve 11 is opened. It is never operated (valve opening degree curve 40 after water supply control in FIG. 4, middle row in FIG. 2). The water supply pump 5 is started, and the rotation speed of this water supply pump is α. r''pm (water supply pump rotation speed curve 37 in Figure 4), the water supply controller 31 gradually turns the water supply control valve 9 on (water supply control valve opening curve 39 in the same figure), and at the same time, the water supply The pump 5 is gradually increased to a minimum rotational speed α.rpm.

When the rotation speed of the water supply pump 5 gradually increases and the water supply pump outlet pressure in the water supply branch pipe 1 reaches its upper limit, the differential pressure measured by the differential pressure gauge 35 decreases. Eventually, this differential pressure becomes δKg/
cti (differential pressure curve 41) in the same figure), the water supply controller 31 fully opens the water supply control bypass valve 13 (the fourth
Water supply control bypass valve opening curve 43) in the figure. therefore,
The service-in timing for fully opening the water supply control bypass valve 13 to supply water from the water supply pump 5 to the water supply main pipe 23 can be made to coincide with the time point 29 when the second water supply pump needs to be turned on, and the water supply control tIl consequent condition can be set at the optimal timing. 11 can be opened.

Further, since the differential pressure becomes 0 when the water supply control bypass valve 13 is fully opened, excessive pressure does not act on the check valve 7, and the integrity of the check valve 7 can be ensured.

In the above embodiment, two water supply pumps are installed in parallel in the water supply system, but three or more pumps may be installed in parallel.

〔Effect of the invention〕

As described above, the water supply IT, II control device according to the present invention is provided with the main device, the water supply branch pipe is provided with the water supply pump, the water supply request valve, and the water supply control bypass valve, and the water supply controller that controls these is arranged to control the water supply in the pond. When the water supply pump is operated during operation of the water supply pump, the water supply control pipe valve is directly opened based on the water supply pressure in the water supply main pipe and the differential pressure between this water supply pressure and the water supply pump outlet pressure of the water supply branch pipe. Because of this configuration, when the second or more water supply pumps whose water supply pressure is already high are turned on, unnecessary operation of the water supply control valve is not performed, and the water supply control bypass valve is opened at the optimal timing. Can be done. As a result, the service-in timing of the water supply pump operated as a second or more pump can be optimized, and the integrity of the check valve on the outlet side of the water supply pump can be ensured. Play.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the water supply control device according to the present invention, FIG. 2 is an internal configuration diagram of the water supply side IIL device in FIG. 1, and FIGS. 3 and 4 are diagrams of this embodiment. FIG. 5 is a graph showing the relationship between various valve opening degrees and the number of revolutions of the water supply pump when the water supply pump is operated as the first and second pump in the water supply control system, respectively. An operation diagram showing the operation when the water supply pump is turned on for the second minute,
Fig. 6 is a system diagram showing a conventional water supply control device, Fig. 7 is an internal configuration diagram of the water supply controller shown in Fig. 6, and Fig. 8 is a diagram showing various valves when the water supply pump is operated in the conventional water supply control device. Graphs showing the relationship between the opening degree and the feed water pump rotation speed, and FIGS. 9 and 10 are operation diagrams showing the operation when the water feed pump is turned on for the second minute in a conventional water feed control device. DESCRIPTION OF SYMBOLS 1... Water supply branch pipe, 5... Water supply pump, 7... Check valve, 9... Water supply control valve, 13... Water supply control bypass valve, 23... Water supply main pipe, 31.・・Water supply controller, 3
3... Water supply pressure cam 1.35... Differential pressure gauge. Applicant's agent Hisashi Hatano Figure 2 Figure 15 117 Figure Time Figure 8 Each Figure 9 II Io Figure

Claims (1)

[Scope of Claims] 1. In a water supply control device for a water supply system in which a plurality of water supply pumps are installed in parallel, a water supply pump installed in each of a plurality of water supply branch pipes branched from a water supply main pipe, and each of the above-mentioned water supply pumps is provided. A water supply control valve installed in a water supply branch pipe, a water supply control bypass valve installed in a bypass pipe that bypasses this water supply control valve,
and a water supply controller connected to the water supply pump, water supply control valve, and water supply control bypass valve to control the pump rotation speed and valve opening, and the water supply controller controls the water supply pump when other water supply pumps are operated. When operating, the water supply bypass valve is configured to be directly opened based on the water supply pressure in the water supply main pipe and the differential pressure between this water supply pressure and the water supply pump outlet pressure of the water supply branch pipe. water supply control device. 2. The opening operation of the water supply control bypass valve by the water supply controller is as follows:
The differential pressure value when the water supply pressure is greater than or equal to the maximum water supply pressure value that can be obtained when other water supply pumps are operated at the lowest rotation speed, and the differential pressure is the time required to fully open the water supply control bypass valve from the time when the water supply pump needs to be turned on. The water supply control device according to claim 1, which is executed when the water supply control device reaches the point in time.