JPS62132127A - Purge type level gage - Google Patents

Abstract

PURPOSE:To reduce the number of pipes penetrating a shielding wall by providing the inside of the shielding wall with an air tank for supplying purge pipes with a purge gas and a plurality of humidifying tanks for humidifying the purge gas and providing the outside of the shielding wall with a water tank for supplying the humidifying tanks with water. CONSTITUTION:A plurality of purge pipes 1A and 1B for discharging a purge gas into a liquid 3 to be measured in a plurality of storing tanks 7 provided inside a shielding wall 6 and a plurality of differential pressure transmitters 17 for measuring a back pressure acting on the pipes 1A and 1B are provided. Further, the inside of the wall 6 is provided with an air tank 28 for supplying the pipes 1A and 1B with a purge gas and a plurality of humidifying tanks 32A and 32B for humidifying the purge gas supplied to the pipes 1A and 1B from the air tank 28. On the other hand, the outside of the wall 6 is provided with a water tank 40 for supplying the humidifying tanks 32A and 32B with water. Thus, since only conduits 29 and 43 penetrate the wall 6 regardless of the number of the storing tanks 7, a shielding effect against radiation further improves.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention is used for measuring the liquid level and density of a liquid in a liquid storage container such as a waste liquid treatment facility of a nuclear power plant or a nuclear fuel reprocessing plant. Regarding purge type liquid level gauge.

(Technical background of the invention and its problems) For example, purge type liquid level gauges used in liquid storage containers such as waste liquid treatment facilities of nuclear power plants and nuclear fuel reprocessing plants use gas as the purge fluid. This purge gas forms bubbles at the tip of the purge tube and is released into the liquid being measured.This phenomenon is generally referred to as bubbling. While the bubbles are growing, the inner circumferential surface of the tip of the purge tube is not in contact with the liquid to be measured and is in a dry state due to the purge gas.On the other hand, after the bubbles are released from the purge tube, the inner circumferential surface of the tip of the purge tube is supposed to come into contact with the liquid to be measured, and the inner circumferential surface of the tip end of the purge tube repeats this drying and contact with the liquid to be measured.

Due to this bubbling phenomenon, as shown in FIG. 2, compounds in the liquid to be measured 3 are salted out on the inner circumferential surface 2 of the tip end of the purge tube 1, and this salt 4 is solidified. The salt 4 that has adhered to and solidified on the inner circumferential surface 2 of the purge tube 1 gradually grows due to repetition of the bubbling phenomenon described above, and gradually closes the tip opening 5 of the purge tube 1. As the purge pipe 1 becomes increasingly clogged with salt 4, the inner diameter of the purge pipe 1 gradually becomes smaller, and as the inner diameter of the purge pipe 1 becomes smaller, the pressure loss of the purge gas increases due to the orifice effect, which may cause measurement errors. .

For example, in a purge pipe 1 with an inner diameter of 10a+m, if the flow rate of purge gas is 3041/h, when the inner diameter of the purge pipe 1 becomes 4 to 5Nn due to blockage of the purge pipe 1 with salt 4, the influence of pressure loss of the purge gas began to appear,
When the inner diameter decreases to around one cocoon, the measurement error increases rapidly.

Therefore, in the conventional purge type liquid level gauge, even though the liquid to be measured is not being operated in such a way that the liquid to be measured increases, the indicated value of the liquid level gauge may increase due to blockage at the tip of the purge pipe 1. This phenomenon occurred and caused a major problem in operation monitoring and control.

Therefore, in order to prevent the tip of the purge pipe 1 from clogging due to the bubbling phenomenon, purge type liquid level gauges have been used which are equipped with a mechanism for humidifying the purge gas.

First, a purge type liquid surface 31 equipped with such a humidifying mechanism
The conventional one will be explained with reference to FIG. Furthermore, this third
The purge type liquid level J1 shown in the figure is configured so that the density of the liquid 3 to be measured can be measured.

In FIG. 3, a closed storage tank 7 in which the liquid to be measured 3 is stored is provided below the horizontal shielding wall 6, and the storage tank 7 is connected to the liquid to be measured by a supply pipe 8. A liquid 3 is supplied, and the liquid 3 to be measured is discharged from this storage tank 7 through a discharge pipe 9. A pair of purge pipes IA and IB that penetrate the shielding wall 6 face the storage tank 7, and are designed to purge purge gas into the liquid 3 to be measured and measure the back pressure. In addition, the tips of both purge pipes IA and 1B are connected to the storage tank 7.
are vertically spaced apart by a predetermined distance within the liquid to be measured 3. This is because the density of the liquid 3 to be measured is measured by the differential pressure between the back pressures acting on both purge pipes 1Δ and 1B.

Each purge pipe 1Δ, IB is a conduit 10A.

Pressure source 11 for supplying purge gas via 10B
The flow rate of purge gas from the pressure source 11 is connected to each conduit 10A and IOB.
l i flow regulators 12A, 12B, each conduit 10A,
Flow meter 13A, 13B, which measures the flow rate of purge gas flowing inside 10B! 1: Humidifiers 14A and 14B are interposed to humidify the purge gas flowing in each of the conduits 10A and 10B. Each humidifier 14A, 14B is configured by storing water 16 in a closed container 15A, 15B.

At the upper ends of purge T21A, 1B, both purge pipes IA, I
A differential pressure transmitter 17 is installed that transmits a signal proportional to the back pressure difference acting on B, and this differential pressure transmitter 7
A pressurizer 1B is provided to periodically check the performance of the 517. This pressurizer 18 has a cylinder 19, and this cylinder 19 is partitioned into a first chamber 21J3 and a second chamber 22 by a bismine 20 that has an interior space of ffl fJl.

Further, these first chamber 21 and second chamber 22 are connected to the conduit 2
3.24 to the differential pressure transmitter 17. Note that the conduits 23 and 24 can be attached to and detached from the differential pressure transmitter 17. Furthermore, the piston 20 has a cylinder 1
A piston rod 20a is protruded from the piston 9 and extends outward from the piston 2.
0 within the cylinder 19 to open the conduit 23.24.
C starts to apply pressure to the differential pressure transmitter 17 via
There is. Furthermore, each purge pipe 1A, IB on the side of the differential pressure transmitter 17 is provided with a cutoff valve 25A, which is a manual valve, depending on the connection portion with the conduit pipes 10Δ, 10B.

25B is installed, how to use these shutoff valves 25A
, 25Bf3 and the differential pressure transmitter 17, a communication pipe 26 is provided that communicates the purge pipes 1A and IB between the
6 is provided with a zero adjustment valve 27 which is a manual valve.

According to the above-mentioned configuration, the flow rate is adjusted from the pressure saw source 11 by the flow rate adjusting rods 12A and 12B, and the flow rate is monitored by the flow rate meters 13A and 13B, respectively.

The purge gas flowing through 10B is humidified 2S14A.

When passing through 14B, the water absorbs the opening force of the water 16 in the locks 15A, 15B and is supplied to the purge pipes IA, 1B. Therefore, even when the inner circumferential surfaces 2 of the ends of the purge pipes IA, 1B are not in contact with the liquid to be measured 3 due to the bubbles of the purge gas, moisture is present in the purge gas.
Even if the bubbling phenomenon is repeated, there is little risk of salting out of compounds in the liquid to be measured 3 on the inner peripheral surfaces 2 of the tips of the purge pipes IA and 1B. Therefore, there is little possibility that the front end opening 5 of the purge pipe IA, 1 [3 will be blocked, which would cause a measurement error.

On the other hand, periodic calibration for checking the performance of the differential pressure transmitter 17 is performed as follows.

First, the cutoff valves 25Δ for both purge pipes IA and IB.

25Bf opens. Thereafter, the zero adjustment valve 27 is opened to supply zero differential pressure to the differential pressure transmitter 17, and in this state, the zero signal of the differential pressure transmitter 17 is adjusted. Next, the zero adjustment valve 27 is closed and the pressurizer 18 applies a reference pressure to the differential pressure transmitter 17 via the conduits 23 and 24, and in this state, the span of the differential pressure transmitter 17 is adjusted.

However, in the conventional purge type liquid level gauge described above, each purge pipe 1 has a flow ω regulator 12 and a flow ff1.
i113 and humidifier 14 are required, the structure becomes complicated, and two shielding walls 6 are required for one storage tank 7.
The real purge pipes 1A and 1B will pass through. Furthermore, a humidifier 14A.

A water supply pipe (not shown) also penetrates the shielding wall 6 in order to maintain the water level of the water tank 14B at a constant level at all times. However, since a plurality of storage tanks 7 are usually provided in an atomic couplant, there is a problem in that the structure for preventing leakage of radiation becomes complicated.

[Purpose of the invention]

The present invention has been made with these points in mind, and it is an object of the present invention to provide a purge type liquid level gauge in which the number of pipes penetrating the shielding wall is reduced compared to conventional ones.

[Summary of the invention]

The present invention includes a plurality of purge pipes for discharging purge gas into a liquid to be measured in a plurality of storage tanks disposed inside a shielding wall, and a plurality of purge pipes for measuring back pressure acting on these purge pipes. A purge type liquid level gauge having a differential pressure transmitter,
An air tank for supplying purge gas to each purge pipe and a plurality of humidifying tanks for humidifying the purge gas supplied from the air tank to the purge pipes are disposed inside the shielding wall, and the shielding wall The humidifying tank is characterized by a water tank provided outside the humidifying tank for supplying water to each humidifying tank.

[Embodiments of the invention]

The present invention will be explained below with reference to embodiments shown in the drawings. Note that the same components as those of the conventional device described above are denoted by the same reference numerals in the drawings, and the explanation thereof will be omitted.

FIG. 1 shows an embodiment of the present invention, in which a storage tank 7 for a liquid to be measured 3 to which a supply pipe 8 and a discharge pipe 9 are connected is disposed within a vertical shielding wall 6. . An air tank 28 is arranged above the storage tank 7.

Compressed air is supplied from an air supply source (not shown) through a conduit 29 that penetrates the shielding wall 6.

This conduit 29 is provided with an electromagnetic valve 30 for controlling the opening of compressed air supplied to the air tank 28, and a precision pressure gauge 31 for measuring the pressure of the compressed air within this conduit 29.

A pair of humidifying tanks 32A, 3 are provided on the sides of the storage tank 7.
2B, and water 33 for humidifying the purge gas is stored in each humidifying tank 32A, 32B. On the other hand, the air tank 28 has a plurality of capillary tubes 3.
/1.34 is connected, both humidifying tanks 32A, 3
The lower end of each capillary tube 34 faces into the water 33 of 2B, so that the purge gas that has passed through the capillary tube 311 is humidified in the water 33. The other capillary tube 34 connected to the air tank 28 is for another not-shown humidifying tank, and the air tank 28 is connected to a pressure regulating pipe 35 in which a solenoid valve 36 is interposed.

A differential pressure transmitter 17 is connected to the upper end, and a storage tank 7 is connected to the lower end.
A pair of purge pipes IA and I facing into the liquid to be measured 3
B has a solenoid valve 37A, respectively.

37B is interposed and J3 is this solenoid valve 37A.

Purge pipe IA on the differential pressure transmitter 17 side from 37B.

1B includes a conduit 38A for supplying purge gas from the humidifying tanks 32A and 32B to the purge pipes 1Δ and 1B.
, 38B are connected. Further, a solenoid valve 39 is interposed in the low-pressure side conduit 38A whose lower end is located upward.

A water tank 40 is disposed outside the shielding wall 6, and water is supplied to the water tank 40 from a water supply source (not shown) through a water supply pipe 41 in which a manual valve 42 is installed. It has become. Water in the water tank 40 is supplied to each humidifying tank 32A through a conduit 43 which is provided with a solenoid valve 44 and passes through the shielding wall 6 L'J.

In addition to being supplied to 32B, it is also supplied to other systems 45. Moreover, the water in the water tank 40 is
Water is drained through a drain pipe 46 in which a solenoid valve 47 is interposed, and on the other hand, an atmospheric release pipe 48 is connected to the upper end of the water tank 40 .

And each solenoid valve 30, 36, 37△, 37B.

The opening and closing of valves 39, 44, and 47 are controlled by a solenoid valve controller 49.

Next, the operation of the embodiment described above will be explained.

Air, which is the purge gas, is supplied from the conduit 29 into the air tank 28, and the flow rate is restricted by the capillary tube 34 to a nearly constant flow m, and then the air is supplied to the humidifying tank 32A,
32B. And these humidification tank 3
2A, 32B, water 33 is passed through and humidified, and the purge pipe 1A.

The liquid to be measured 3 is supplied from 1B. Therefore, even if the bubbling phenomenon is repeated, the inner circumferential surfaces of the lower ends of both purge pipes 1A and IB are always moist.
Salting out does not occur on the inner circumferential surface of the lower end of B. In addition, both humidification tanks 32A.

Water 33 is supplied to 32B from a water tank 40 via a conduit 43.

By the way, if the height from the lower end of the purge pipe 1B in the storage tank 7 to the liquid level of the liquid to be measured 3 is A, the pressure in the storage tank 7 is Pl, and the specific weight of the liquid to be measured 3 is γ, then the purge pipe The back pressure generated within 1B is P1+Aγ. At this time,
Inside the water tank 4o. Note that the pressures Pi, P2.
P3 is shown as a difference from the human pressure, and therefore, the pressure P3 in the water tank 40, which is communicated with the atmosphere through the atmosphere release pipe 48, becomes zero.

If the liquid level of the liquid to be measured 3 in the storage tank 7 rises or falls, both humidifying tanks 32A, 32BJ3
and the liquid level in the water tank 40 changes ωJ, but their relative positions maintain a difference γ of -'-+A and reach equilibrium. Therefore, if the capacity of the water tank 40 is made larger than the capacity of the humidifying tanks 32A and 32B, the liquid level of the water tank 40 will hardly change.

Next, to explain the calibration of the differential pressure transmitter 17, first, open the solenoid valve 47 installed in the drain pipe 46 to measure and drain the water in the humidifying tanks 32A, 32B and the water tank 40. Then, this discharged water is treated as waste liquid. Thereafter, each electromagnetic valve 37A, 37B, and 44 are opened, and the electromagnetic valve 36 is opened, and the pressure in the air tank 28 is lowered to about 100 meters of water column.

At this time, the high pressure side of the differential pressure transmitter 17 is connected to the humidifying tank 32.
Air tank 2 via B and capillary tube 34
8, and the low pressure side of the differential pressure transmitter 17 is connected to a solenoid valve 39, a humidifying tank 32A, and a capillary tube 3.
It will be connected to the air tank 28 via 4. Therefore, no differential pressure is applied to the differential pressure transmitter 17 in this state. Here, in order to adjust the zero point of the differential pressure transmitter 17 without going to the 3Q location of the differential pressure transmitter 17, it is necessary to perform hardware adjustment on the circuit from the control room for process operation (not shown) or by using a computer. If adjustment is performed using software, the zero point adjustment of the differential pressure transmitter 17 can be performed without going to the installation site, and the calibration time can be shortened. The reference pressure at this time is determined by measuring the pressure within the air tank 28, that is, the pressure within the two conduit pipes, using a precision pressure gauge 31.

Next, the procedure for span calibration of the differential pressure transmitter 17 will be explained. First, the solenoid valve 39 of the conduit 38A is closed to seal the low pressure side of the differential pressure transmitter 17.

Thereafter, a conduit 29 that supplies compressed air to the air tank 28
The solenoid valve 30 applies a calibration pressure in the air tank 28 with compressed air. A rough guide for this calibration pressure is approximately 1/2 of the measurement range of the differential pressure transmitter 17. For example, when calibrating a differential pressure transmitter 17 with a full range of 3000 m of water, the high pressure side pressure is set to 1800 m of water, and the initial pressure for zero point calibration is 300 m of water.
As differential pressure, 1800-300=150ONR (water column)
is applied. Then, when the indication from the differential pressure transmitter 17 becomes stable, the output instruction from the differential pressure transmitter 17 is read, and at the same time, the pressure is measured by the precision pressure gauge 31.

In this way, the indicated value of the differential pressure transmitter 17 is 1500 water columns.
The difference between the measured value of HR and the precision pressure gauge 31, that is, at 1/2 of the measurement range, and the differential pressure transmission 'a when zero differential force is input.
The span calibration of the differential pressure transmitter 17 is performed by comparing the difference in the water column 300# applied to the differential pressure transmitter 17. Note that the calibration value can be adjusted in the same manner as in the case of seven differential pressure inputs.

After completing the calibration through the above steps, purge pipes 1A and I
The solenoid valves 37A and 37B of B and the solenoid valve 39 of the conduit 38Δ that communicates the humidifying tank 32A and the purge pipe 1Δ are opened, and then the pressure inside the air tank 28 is adjusted to the normal measurement pressure (9/1 to 1.4). ci). Next, the solenoid valve 47 of the drain pipe 46 is closed, and the solenoid valve 44 of the conduit 43 that supplies the water 33 in the water tank 40 to the humidifying tanks 32A, 32B is opened. Then, when water is supplied into the water tank 40 via the manual valve 42, the water is supplied to both humidifying tanks 32△ via the conduit 43.

Water is supplied to 32B and the normal measurement state is restored.

According to the embodiment described above, the number of pipes that penetrate the shielding wall 6 is only two conduits and 43, and even if the number of storage tanks 7 and the number of purge pipes 1 increase, Since it does not change, radioactivity countermeasures can be easily taken. In addition, when calibrating the differential pressure transmitter 17, there is no need to approach the differential pressure transmitter 17 installed at the site, which was required in the past, so the calibration time can be shortened and the risk of worker exposure to radiation is reduced. It can be further reduced. Furthermore, the number of personnel required for calibration work conventionally required one person each on site and in the control room where the indicator n1 device is located, but in this embodiment, calibration can be performed by only one person in the control room, reducing the number of personnel. I can do it. Furthermore, since the calibration time can be shortened, the operating time of the plant is increased, and the operating rate is improved.

In addition, each electromagnetic valve 30, 36.37A, 37B.

If the opening/closing operations of 39, 44, and 47, the reading of the measured value of the precision pressure gauge 31, and the reading of the differential pressure transmitter output are performed automatically under program control, complete automatic calibration becomes possible. In this case, reading errors when reading measured values by humans are eliminated, so the reliability of calibration is further improved. Further, although this embodiment is configured to measure the density of the liquid to be measured 3, the liquid level of the liquid to be measured 3 can also be easily measured.

〔Effect of the invention〕

As explained above, according to the present invention, regardless of the number of storage tanks, what passes through the shielding wall is a conduit that supplies compressed air to the air tank, and a conduit that supplies water from the water tank to each humidifying tank. Since there are two conduits, the shielding effect against radiation can be further improved.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing an embodiment of the purge type liquid level gauge according to the present invention, Figure 2 is a longitudinal sectional view showing the state of salting out at the tip of the purge pipe, and Figure 3 is a conventional purge type liquid level gauge. FIG. 1 is a configuration diagram. DESCRIPTION OF SYMBOLS 1... Purge pipe, 3... Liquid to be measured, 6... Shielding wall, 7... Storage tank, 11... Pressure source, 17...
・Differential pressure transmitter, 18... Pressurizer, 28... Air tank, 29... Conduit, 31... Precision pressure gauge, 32A,
32B... Humidification tank, 35... Pressure regulating pipe, 38A,
38B... Conduit, 40... Water tank, 43... Conduit, 46... Drain pipe, 48... Atmospheric waste pipe, 4
9...Solenoid valve controller. Applicant's agent Mr. Sato $ l Figure 3 Figure 3

Claims (1)

[Claims] 1. A plurality of purge pipes for discharging purge gas into a liquid to be measured in a plurality of storage tanks disposed inside a shielding wall, and a back pressure acting on these purge pipes. In a purge type liquid level gauge having a plurality of differential pressure transmitters to be measured, an air tank for supplying purge gas to each purge pipe is provided inside the shielding wall, and purge gas is supplied from the air tank to the purge pipe. A purge type liquid level gauge, comprising a plurality of humidifying tanks for humidifying water, and a water tank for supplying water to each humidifying tank outside the shielding wall. 2. A solenoid valve is installed in each of the pressure regulating pipe for adjusting the internal pressure of the air tank, the purge pipe, the conduit leading water from the water tank to each humidifying tank, and the drain pipe discharging water from the water tank. , each solenoid valve is controlled by a solenoid valve controller.
Purge type liquid level gauge as described in section.