JP3550266B2 - Water level detection piping - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water level detection pipe such as a feed water heater or a drain tank using a seal diaphragm type differential pressure transmitter in a nuclear power plant.
[0002]
[Prior art]
Water level detection using a seal diaphragm type differential pressure transmitter has become mainstream in recent years as a method for detecting a water level of a feed water heater, a drain tank, and the like in a nuclear power plant.
FIG. 5 shows an example of a system configuration of a water level detection pipe using a conventional seal diaphragm type differential pressure transmitter.
[0003]
In FIG. 5, reference numeral 1 denotes a feed water heater, and a detection seat for detecting a water level is provided at upper and lower portions of the feed water heater 1, and a detection pipe header 2-1 is provided on the detection seat via a detection source valve 3. It is connected. The upper and lower detection headers 2-1 are commonly connected to each other, and are branched at appropriate two locations to be connected to a detection pipe 2-2. The detection pipe 2-2 has a water level detection balance. In addition to the transmitter, a water level switch and the like are installed as pipes.
[0004]
As the water level transmitter pipe, an instrument inlet valve 4 is provided in each detection pipe 2-2, and a flange 14 is attached to the end side thereof. Are connected respectively.
[0005]
Further, since the internal fluid of the upper detection pipe 2-2 is high-temperature steam, a tee 13 is provided at an end of the upper detection pipe 2-2, and an upper flange 14 is connected to a lower end of the tee 13. By storing water, protection of the diaphragm 11 and prevention of hydrogen permeation on the diaphragm surface are performed. Further, a test / vent valve 8 and a closing plug 9 are provided at the upper end of the tee 13 for instrument calibration and venting.
[0006]
[Problems to be solved by the invention]
However, such a conventional water level detection pipe has the following problems.
(1) Since water cannot be injected through the space between the upper and lower detection pipes 2-2, accurate calibration of the instrument was not possible during instrument calibration.
(2) Since the test / vent valve 8 is installed between the instrument inlet valve 4 and the flange 14 by the tee 13, the condensed drain remaining between the instrument inlet valve 4 and the flange 14 during flange maintenance is removed before the flange is removed. I couldn't do that. This condensate drain is a condensate of the steam generated in the reactor, and there is a risk of worker exposure when the flange is removed.
(3) The height of the water reservoir is 150 to 180 mm because the water reservoir in front of the upper flange is secured by using the tee 13. Therefore, when the plant is started, the inside of the feed water heater 1 is connected to the condenser to be in a vacuum, and the water in the water pool evaporates and the head pressure disappears. Therefore, the apparent water level is instructed to be higher by 150 to 180 mm. Would. In the case of the feed water heater, the above error was not negligible because the water level control range was normally about ± 150 mm.
(4) The water level detection pipe has a diameter of 50A, and the water level inside the feed water heater is directly transmitted, so that the water level detected by the transmitter is detected as a noise-like mustache. In the case of ripples, accurate water level detection was not possible.
[0007]
An object of the present invention is to solve the above problems and to provide a highly reliable water level detection pipe capable of detecting the water level of a feed water heater and a drain tank in a nuclear power plant with high accuracy.
[0008]
[Means for Solving the Problems]
According to the present invention, in order to achieve the above object, a water level detection pipe is constituted by the following means.
The invention corresponding to claim 1 connects the detection pipe headers connected to the upper and lower portions of the feed water heater or the drain tank in the nuclear power plant, and branches the appropriate two places to the upper detection pipe and the lower detection pipe. A differential pressure transmitter for connecting a detection pipe, providing an instrument inlet valve for each of these detection pipes, and detecting a change in the water level in the feed water heater or the drain tank as a change in the differential pressure on a flange provided on the end side. In the water level detection pipe formed by connecting the above-mentioned diaphragms, a crank-type water pool portion whose water pool height is adjustable is provided in front of the flange of the upper detection pipe.
[0009]
In the water level detection pipe having the above configuration, the height of the water reservoir can be adjusted by changing the inclination angle of the crank portion. And can be minimized irrespective of the welding leg length .
[0014]
The invention corresponding to claim 2 connects the detection pipe headers connected to the upper and lower portions of the feedwater heater or the drain tank in the nuclear power plant, and branches the appropriate two places to the upper detection pipe and the lower detection pipe. A differential pressure transmitter for connecting a detection pipe, providing an instrument inlet valve for each of these detection pipes, and detecting a change in the water level in the feed water heater or the drain tank as a change in the differential pressure on a flange provided on the end side. In the water level detection pipe connecting the diaphragms, the upper and lower detection pipes are connected to each other on the outlet side of the instrument inlet valve by a communication pipe, and a special flange having a hole for draining and washing is used as a flange. A crank-type water reservoir portion having an adjustable water reservoir height was provided in front of the flange of the upper detection pipe, and connected to the lower detection pipe header. Providing a diaphragm section analysis pipe.
[0015]
In the water level detection pipe with the above configuration, the accuracy of instrument calibration is improved, the workability during flange maintenance is improved, the effect on the water level measurement even when condensed water in the water reservoir evaporates, and the water supply is minimized. Water level measurement can be performed without being affected by ripples inside the heater.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram showing an embodiment of a water level detection pipe according to the present invention, and the same parts as those in FIG.
[0017]
In FIG. 1, reference numeral 1 denotes a feed water heater, and a detection seat for detecting a water level is provided in upper and lower portions of the feed water heater 1, and a detection pipe header 2-1 is connected to the detection seat via a detection source valve 3. Have been. The upper and lower detection headers 2-1 are connected in common with each other, and are appropriately branched at two locations to be connected to detection pipes 2-2. 4 and a special flange 7 is connected to an end thereof.
[0018]
As shown in FIG. 2, a pressure receiving diaphragm 11 of a water level transmitter for detecting a pressure difference between the upper and lower detection pipes 2-2 is connected to the special flange, and drainage and cleaning are performed below the detection pipe connection port. A hole 7a is also provided, which is connected to a vent / test valve 8 and closed by a closing plug 9.
[0019]
A connecting pipe 5 is connected between the outlet side of the instrument inlet valve 4 of the upper and lower detecting pipes, and a water reservoir 6 is provided in an upper detecting pipe between the connecting pipe 5 and the special flange 7.
As shown in FIGS. 3 (a) and 3 (b), the water reservoir 6 is composed of a short pipe 6a and two elbows 6b and 6c connected to both ends of the short pipe 8a. Can be adjusted by changing the angle α of the crank portion.
[0020]
On the other hand, a cross tee 12 is provided in the lower detection pipe 2-2, and a throttle 10 is provided in the detection pipe head 2-1 before the cross tee 12. The aperture 10 has a tapered upper opening as shown in FIG. 4, and has a shape in which dust does not easily accumulate.
[0021]
With the water level detection pipe having such a configuration, since the communication pipe 5 is provided between the upper and lower detection pipes 2-2 on the outlet side of the instrument inlet valve 4, the instrument inlet valve 4 is closed at the time of instrument calibration and the test / test is performed. By opening the drain valve 8 and connecting the tube to the closing plug 9 on the lower detection pipe side, it is possible to calibrate the instrument while watering the tube.
[0022]
In addition, since a hole 7a for draining and cleaning is formed in the special flange 7 and a test / vent valve 8 is connected to the hole 7a, the test / vent valve 8 is opened before the flange is removed at the time of flange maintenance. By removing the condensing drain inside the piping and removing the flange 7 after cleaning, the danger of exposure to workers can be avoided.
[0023]
Further, the structure of the water reservoir 6 provided between the connection portion of the connecting pipe 5 of the upper detection pipe 2-2 and the special flange 7 is a crank type, and the height of the water reservoir 6 is the angle of the crank. Since the height can be adjusted by changing α, the height of the water reservoir 6 can be minimized (50 mm) irrespective of the size of the components of the component and the length of the welding leg.
[0024]
On the other hand, since the lower pipe connection port of the cross tee 12 connecting the lower detection pipe header 2-1 and the lower detection pipe 2-2 is provided with the throttle 10 having an upper opening tapered, the inside of the feed water heater main body is provided. Stable water level measurement that is not affected by the rise of water level can be performed.
[0025]
In the above embodiment, the water level detecting pipe of the feed water heater has been described. However, the water level detecting pipe of the drain tank can be configured in the same manner as the above-described embodiment.
[0026]
【The invention's effect】
As described above, according to the present invention, the accuracy of instrument calibration is improved, the workability at the time of flange maintenance is improved, the influence on the water level measurement even when the condensed water in the water reservoir evaporates, and the feed water heater or It is possible to provide a water level detection pipe capable of measuring a water level without being affected by, for example, waving inside the drain tank.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a water level detection pipe according to the present invention.
FIG. 2 is a sectional view showing a structure of a special flange in the embodiment.
FIGS. 3 (a) and 3 (b) show the structure of a water reservoir in the embodiment, wherein FIG. 3 (a) is a perspective view and FIG. 3 (b) is for explaining height adjustment of the water reservoir. Front view.
FIG. 4 is a cross-sectional view showing the structure of the diaphragm in the embodiment.
FIG. 5 is a system diagram showing a configuration example of a conventional water level detection pipe.
[Explanation of symbols]
1 ... feed water heater 2-1 ... detection header 2-2 ... detection pipe 3 ... detection source valve 4 ... instrument inlet valve 5 ... communication pipe 6 ... water reservoir 7 ... special flange 8 ... … Test / vent valve 9… Closing plug 10… Restrictor 11… Diaphragm 12… Cross tee

Claims (2)

In the nuclear power plant, the detection pipe headers connected to the upper and lower parts of the feed water heater or the drain tank are connected to each other, and the upper detection pipe and the lower detection pipe are connected by appropriately branching out the two places. A water level detection system in which a meter inlet valve is provided in the pipe and a diaphragm of a differential pressure transmitter that detects a water level change in the feed water heater or the drain tank as a change in differential pressure is connected to a flange provided on an end side. In piping,
A water level detection pipe, wherein a crank-type water pool portion having an adjustable water pool height is provided in front of the flange of the upper detection pipe. In the nuclear power plant, the detection pipe headers connected to the upper and lower parts of the feed water heater or the drain tank are connected to each other, and the upper detection pipe and the lower detection pipe are connected by appropriately branching out the two places. A water level detection system in which a meter inlet valve is provided in the pipe and a diaphragm of a differential pressure transmitter that detects a water level change in the feed water heater or the drain tank as a change in differential pressure is connected to a flange provided on an end side. In piping,
The upper and lower detection pipes are connected to each other on the outlet side of the instrument inlet valve by a communication pipe, and a special flange having a drain hole and a cleaning hole is used as the flange. A water level detection pipe, wherein a crank-type water pool portion whose water sump height is adjustable is provided, and a throttle is provided in a lower detection pipe connected to the lower detection pipe header.

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