JPH0435693B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a purge type liquid level meter/density meter suitable for measuring the liquid level/density in a liquid storage container such as a waste liquid treatment facility of a nuclear power plant or a nuclear fuel reprocessing plant. In particular, the present invention relates to a purge type liquid level gauge which has little measurement error and whose detector can be calibrated by remote control. (Prior Art) Purge type liquid level gauges and density meters used in waste liquid treatment facilities of nuclear power plants, nuclear fuel reprocessing plants, etc. use gas as a purge fluid. This purge type liquid level gauge is shown in FIG. FIG. 8 is a configuration diagram showing a conventional purge type liquid level gauge. In the figure, reference numeral 71 is a differential pressure detector, and this differential pressure detector 71 has two purge pipes 7.
2. A purge pipe 73 is connected. A differential pressure detector 7 is installed in the purge piping 72 and the purge piping 73.
A manual valve 74 and a manual valve 75 used for the operation and calibration of 1 are provided, and furthermore, an air supply pipe 76 and an air supply pipe 77 for air purge are connected, respectively. One of the purge pipes 72 is inserted into the solution to be measured 79 in the tank 78, and the tip of the other purge pipe 73 is located in the gas phase part of the tank 78. The purge pipe 72 and the purge pipe 73 are connected by a pressure equalizing pipe, and a manual valve 80 is provided in the pressure equalizing pipe. On the upstream sides of the air supply piping 76 and the air supply piping 77, there are a flow meter 81 and a flow meter 82 for measuring the flow rate of purge air, a flow rate regulator 83 for keeping the flow constant, a flow rate regulator 84, and a pressure source 85, respectively. It is provided. Further, when calibrating the differential pressure detector 71, a pressure guide pipe 88 provided with a pressure generator 87 is connected to the pressure guide port 86 of the differential pressure detector 71. The principle of normal surface measurement using the purge type liquid level gauge having such a configuration will be explained. First, an operator closes the manual valve 80 and opens the manual valves 74 and 75. The air supplied from the pressure source 85 is passed through the flow regulator 83, while the flow value is monitored by the flowmeter 81 and the flowmeter 82.
The flow rate is adjusted to a constant flow rate by a flow rate regulator 84 and supplied to purge piping 72 and purge piping 73. solution 79
A constant flow of air is discharged from the tip of the purge pipe 72 inside, overcoming the back pressure of the solution 79. As a result, the air pressure in the purge pipe 72 becomes equal to the sum of the gas phase portion of the tank 78 and the back pressure corresponding to the height of the solution 79, and the air pressure in the purge pipe 73 becomes equal to the gas phase portion of the tank 78. The differential pressure detector 71 detects a back pressure equivalent to the height of the solution 79, which is the difference between these two pressures. Since this back pressure is proportional to the height of the liquid level A of the solution 79, the liquid level A can be measured by the differential pressure detector 71. Next, a procedure for calibrating the differential pressure detector 71 of the purge type liquid level gauge, which is carried out periodically to confirm its performance, will be explained. First, a worker goes to the installation site of the differential pressure detector 71. Close manual valve 74 and manual valve 75, and open manual valve 80. The purge piping 72 and the purge piping 73 are pressure-equalized, the differential pressure detector 71 is set to zero differential pressure, and the differential pressure detector 71 is
Calibrate the zero differential pressure signal. Next, manual valve 80
is set to "closed", a reference pressure is generated by the pressure generator 87, and this is applied from the pressure guiding port 86 of the differential pressure detector 71. Span calibration is performed by comparing the indicated value of the differential pressure detector 71 with the reference pressure value while applying this reference pressure. (Problems to be Solved by the Invention) According to the conventional differential pressure detector calibration method as described above, a maintenance person goes to the site where the differential pressure detector 71 is installed, and after applying the calibration pressure, It is necessary to compare the reading with the indicator installed in the control room. Further, the pressurizer 87 must be brought to the site, and the differential pressure detectors 71 must be calibrated one by one. This increases the time required for calibration, making it difficult to maintain the accuracy of measuring instruments, increasing radiation exposure for maintenance personnel, and causing problems that shorten operating time and reduce equipment utilization. be. The present invention was made to solve these problems.By remotely calibrating the differential pressure detector, it is possible to shorten the calibration time and save labor for the calibration work, as well as to calibrate the differential pressure detector with high accuracy. The purpose of the present invention is to provide an air purge type liquid level gauge capable of surface measurement. [Structure of the invention] (Means for solving the problem) A first purge pipe is connected to the high pressure side of the differential pressure detector, a second purge pipe is connected to the low pressure side, and further the first purge pipe and the second purge pipe are connected to the high pressure side of the differential pressure detector. A pressure equalization pipe is provided that connects the purge pipes.The first inlet valve is on both upper sides of the first purge pipe, the first outlet valve is on the downstream side, the second inlet valve is on the upstream side of the second purge pipe, and the second inlet valve is on the downstream side of the second purge pipe. has a second outlet valve,
A pressure equalization valve will be installed in the pressure equalization piping. Furthermore, each of these valves is provided with a valve opening/closing device that can be remotely operated. (Function) According to the present invention, the opening/closing operations of each valve required during measurement and calibration of the differential pressure detector are performed by a valve opening/closing device remotely controlled from a central control room. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the first embodiment. In the drawings, reference numeral 1 denotes a differential pressure detector, to which a purge pipe 2 is connected to the high pressure side and a purge pipe 3 to the low pressure side. The purge piping 2 and the purge piping 3 penetrate the thin wall 4 and are vertically installed in parallel, and the tip of the purge piping 2 is inserted into the solution to be measured 23 in the tank 5. is located in the gas phase part of tank 5. A solenoid valve 6 is attached to the upper part of the purge pipe 2, and a solenoid valve 7 is attached to the lower part thereof, and a solenoid valve 8 and a solenoid valve 9 are similarly attached to the purge pipe 3. Further, a pressure equalizing pipe 10 is provided that connects the purge pipe 2 and the purge pipe 3, and a solenoid valve 11 is attached to this pressure equalizing pipe 10. Furthermore, an air tank 13 for supplying a constant flow of air is connected to the upstream side of the purge piping 2 and the purge piping 3 via a capillary 12. A solenoid valve 14 for adjusting the pressure of the air tank is attached to one end of the air tank 13, and a pipe 15 is connected to the other end. A total of 16 solenoid valves 17 are installed, and a pressure source 18 is connected to the upstream side thereof. Further, signal lines 20 of the solenoid valves 6, 7, 8, 9, and 11 are connected to a central control room 22 via a connector 21. In general, solenoid valves come in two types: ``non-energized open'' type and ``non-energized closed'' type. The former opens when the electromagnetic coil of the solenoid valve is de-energized, and the latter closes when the solenoid coil becomes de-energized. Solenoid valve 6, 7, 8
The solenoid valves 11 and 9 are of the "non-energized closed" type. The electromagnetic valves 6, 7, 8, 9, 11 and the differential pressure detector 1 are integrated into a detector module 24, so that they can be easily replaced in the event of a failure. A perspective view of the exterior of the detector module 24 is shown in FIG. 2, and a piping circuit is shown in FIG. As shown in FIG. 2, five solenoid valves 6, 7, 8, 9, and 11 are installed on a solenoid valve base 25. Parts of the purge pipes 2 and 3 and the pressure equalization pipe 10 are housed inside the solenoid valve base 25. The operation of the first embodiment having such a configuration will be explained. In a steady measurement state, the solenoid valves 6, 7,
9, 8, 17 are "open", solenoid valves 14, 11 are "closed"
The state is set to . The air supplied from the pressure source 18 is maintained at approximately 1.4 kg/cm ² in the air tank 13. On the other hand, the back pressure generated in the purge pipe 2 is approximately 2000 mmH ₂ O at maximum, so the air tank 13
The differential pressure between and purge pipe 2 is 1.4Kg/cm ² ~1.2Kg/cm ²
Varies between. Therefore, by restricting the air flow rate with the capillary reach tube 12, the amount of air released from the tips of the purge pipes 2 and 3 can be reduced to
h is adjusted to a certain amount. In this way, during steady measurement, the differential pressure detector 1 measures the differential pressure between the purge piping 2 and the purge piping 3, and since this differential pressure is equal to the back pressure of the solution to be measured 23, the
3 liquid level A is measured. Next, the operation during calibration according to the first embodiment will be explained. (The zero differential pressure is calibrated as follows.) First, the solenoid valves 7 and 9 are closed by remote control from the central control room 22, and the radioactive gas generated in the tank 5 flows to the differential pressure detector 1. After the electromagnetic valve 17 is similarly set to "closed", the electromagnetic valve 14 is set to "open". After this reduces the pressure inside the air tank 13 to about 300mmH ₂ O, the solenoid valve 14
is "closed" and the solenoid valve 11 is "open". Purge piping 2 (high pressure side) and purge piping 3 (low pressure side) are at the same pressure via pressure equalizing piping 11, and the H (high pressure) side inlet and L (low pressure) side inlet of differential pressure detector 1 are electrically connected and zero. This is a differential pressure input. Here, the zero adjustment of the differential pressure detector 1 is performed, but at this time, without going to the installation location of the differential pressure detector 1, the adjustment is done in the central control room 22 (hard adjustment done on the circuit or software done on the computer). adjustment). The reference pressure at this time is determined by measuring the pressure inside the air tank 13 with a precision pressure gauge 16. Next, the procedure for performing span calibration will be described. First, the solenoid valves 8 and 11 are "closed" by remote control from the central control room 22 to seal the L side of the differential pressure detector 1. Next, the electromagnetic valve 17 is opened and compressed air is sent to apply a calibration pressure inside the air tank 13.
After applying the voltage, the solenoid valve 17 is closed. As a guideline for the calibration pressure value, it should be about 1/2 of the measurement range of the differential pressure detector 1. For example, when calibrating a differential pressure detector with a full range of _3000mmH2O , set the H side pressure to 1800mmH2O.
If H ₂ O is used, the differential pressure will be 1800−300=1500mm
_H2O is applied. When the indications from the differential pressure detector 1 and the precision pressure gauge 16 become stable, read both output instructions. From the above, the indicated value of differential pressure detector 1 is 1500 mm.
Compare the difference between H ₂ O and the measured value of the precision pressure gauge 16 (difference between 1/2 of the measurement range and the approximately 300 mm H ₂ O applied to the differential pressure detector when zero differential pressure is input). Perform span calibration of the differential pressure detector 1. This is a method of adjusting equipment using calibration values, and can be performed in the same way as zero differential pressure input. After the calibration is completed according to the above procedure, the solenoid valves 7, 8, 9, and 17 are opened, and the pressure inside the air tank 13 is increased to the pressure during normal measurement, and the state returns to the state of measuring liquid level A. . Next, the effect on measurement due to the heat generated when the solenoid valve is energized will be explained. When the solenoid valves change from a non-energized state to an energized state, heat is generated in each solenoid valve, and the generated heat is transmitted to the air in the purge pipe via the solenoid valve base 25. At that time, if the air inside is sealed, pressure changes will occur, causing errors in measurement or calibration. According to this embodiment, the solenoid valves 6, 7, and 8 are of the non-energized open type, and the solenoid valves 9, 11 are of the non-energized closed type, so that the open/close states of the valves during normal measurement and calibration are as shown in the table below. It becomes like this. *
Those with a mark indicate a energized state, and those without a mark indicate a non-energized state.

[Table] In this case, one solenoid valve is always energized during normal measurement, so the solenoid valve base 25 is preheated. When performing zero point calibration and span calibration,
Two solenoid valves each turn on. in this case,
Although the temperature rises, the rate of increase becomes smaller, improving accuracy during span calibration. On the other hand, when all solenoid valves are set to non-energized type during normal measurement, the relationship between opening/closing patterns and energization is as shown in the table below.

[Table] As shown in the table above, during normal measurement, all
When the OFF solenoid valve performs zero point calibration or span calibration, the 3 solenoid valves turn ON. The influence of this generated heat is large, mainly because the temperature on the L side rises, causing a change in the pressure of the air in the purge pipes 2 and 3, which causes an error in span calibration. Due to this background, in order to minimize the influence of heat generated by solenoid valves during span calibration,
In this embodiment, the solenoid valves 6, 7, and 8 are of a non-energized open type, and the solenoid valves 9, 11 are of a non-energized closed type. Figure 4 shows the effect of heat generated by the solenoid valve during this energization. According to this embodiment, the influence of this heat can be reduced, and the temperature change on the sealed L side can be reduced. Thus, according to the embodiment, the solenoid valves 6, 7,
8, 9, 11, 14, and 17 can be opened and closed and the differential pressure detector 1 can be calibrated by remote control from the central control room 22, thereby saving labor. Furthermore, since the calibration time can be shortened, calibration can be performed more frequently, and the reliability of the differential pressure detector 1 is improved. Furthermore, by combining the energized open type and the energized closed type so as to minimize the influence of the heat generated by the electromagnetic valve in the energized state, the accuracy of span calibration is increased and the measurement accuracy is improved. Next, a second embodiment will be explained. FIG. 5 is an overall configuration diagram of the second embodiment. In the drawings, numeral 31 is a differential pressure detector;
A purge pipe 32 is connected to the high pressure side, and a purge pipe 33 is connected to the low pressure side. The purge piping 32 and the purge piping 33 penetrate the thin wall 34 and extend vertically in parallel, and the tip of the purge piping 32 is inserted into the solution to be measured 53 (particle size is A) in the tank 35. The tip of the purge pipe 33 is located in the gas phase portion of the tank 35. An operating valve 36 is attached to the upper part of the purge pipe 32, and an operating valve 37 is attached to the lower part thereof, and an operating valve 38 and an operating valve 39 are similarly attached to the purge pipe 33. Further, a pressure equalization pipe 40 is provided that connects the purge pipe 32 and the purge pipe 33, and this pressure equalization pipe 40 has an operation valve 4.
1 is attached. This operation valve 36,3
A motor 49 is provided as a driving source for opening and closing operations of the openings 7, 38, 39, and 41. The motor 49 and the signal line 50 of the differential pressure detector 31 are connected to a central control room 52 via a connector 51. Further, an air tank 43 for supplying a constant flow of air is connected to the upstream side of the purge piping 32 and the purge piping 33 via a capillary 42. A solenoid valve 44 for adjusting the pressure inside the air tank is attached to one end of the air tank 43, and a pipe 45 is connected to the other end. A total of 46 and solenoid valves 47 are attached, and a pressure source 48 is connected to the upstream side thereof. Further, signal lines 50 of the electromagnetic valves 44 and 47 and the precision pressure gauge 46 are connected to a central control room 52. The above-mentioned differential pressure detector 31, operation valves 36, 37,
38, 39, 41, purge piping 32, 33, pressure equalization piping 40, motor 49, and connector 51 are integrated to form a detector module 54 that can be attached and detached as a complete set. The perspective view is shown in the 6th
The piping circuit is shown in FIG. 7. As shown in Fig. 6, five operation valves 36, 37, 38, 39, 41
are installed in series on the base 55, and this base 5
Parts of the purge pipes 32 and 33 and a pressure equalization pipe 40 are housed inside the purge pipe 5 . A motor 49 is installed adjacent to this base 55, and a rotating shaft 56 is connected to this motor 49. Furthermore, the motor 49
It is preferable that the motor 49 and the base 55 are separated from each other or are heat-insulated so that the heat generated when the motor is driven is not transmitted to the purge pipes 32, 33 and the pressure equalization pipe 40 via the base 55.
This rotating shaft 56 has disk-shaped cams 58a and 58.
b, 58c, 58d, 58e are fixedly installed, which are the stems 5 of the operation valves 36, 37, 41, 38, 39.
7a, 57b, 57c, 57d, and 57e, and is configured to be opened and closed by moving these stems up and down. Furthermore, cams 58a, 58b, 58c, 58
d and 58e, for example, by cutting out a part of the disk-shaped circumference, the stem moves up and down, and the operating valves 36, 37, 38 are operated as shown below during normal measurement, zero point adjustment, and span adjustment. , 39, and 41 are shaped to allow for combinations of opening and closing.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to shorten the calibration time and increase the frequency of calibration, thereby ensuring maintenance of instrument accuracy. Therefore, the quantitative control of the amounts of uranium and plutonium is improved, and process control in the reprocessing process becomes easier. Furthermore, since remote control is possible, the radiation exposure of maintenance personnel can be reduced, and safety can be improved.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a purge type liquid level gauge showing the first embodiment of the present invention, Fig. 2 is an external perspective view of its detector module, and Fig. 3 shows a piping circuit inside its solenoid valve base. Figure 4 is a diagram showing the thermal effect on measurement of the solenoid valve, Figure 5 is a configuration diagram of a purge type liquid level gauge showing the second embodiment, and Figure 6 is a perspective view of the external appearance of the detector module. 7 are diagrams showing the piping circuit within the valve base, and FIG. 8 is a configuration diagram of a conventional purge type liquid level gauge. 1, 31... Differential pressure detector, 2, 3, 32, 33...
Purge piping, 4, 34...Shiyahei wall, 6,...1st
Inlet valve, 7...first outlet valve, 8...second inlet valve, 9...
Second outlet valve, 11... Equalizing valve, 12, 42... Capillary, 20, 50... Signal line, 22, 52... Central control room, 49... Motor, 56... Rotating shaft, 57a,
57b, 57c, 57d, 57e...Stem, 58
a, 58b, 58c, 58d, 58e...cam, 3
6, 37, 38, 39, 41...operation valve.

Claims (1)

[Claims] 1. A differential pressure detector that detects a fluid pressure difference, a first purge pipe connected to the high pressure side of the differential pressure detector, and a first purge pipe connected to the low pressure side of the differential pressure detector. A pressure equalizing pipe that connects the second purge pipe, a first inlet valve provided on the upstream side of the first purge pipe, a first outlet valve provided on the downstream side, and In a purge type liquid level gauge comprising a second inlet valve provided, a second outlet valve provided downstream, and a pressure equalization valve provided in the pressure equalization pipe, the first inlet valve, the first outlet valve , the second inlet valve, the second outlet valve, and the pressure equalization valve are provided with remotely controllable solenoid valves, and these solenoid valves are a combination of non-energized open type and non-energized closed type solenoid valves. Purge type liquid level gauge. 2 First inlet valve, first outlet valve, second inlet valve, second
2. The purge type liquid level gauge according to claim 1, wherein the outlet valve and the pressure equalization valve are integrated as a detector module. 3. A patent claim characterized in that the first inlet valve, first outlet valve, and second inlet valve are non-energized open type solenoid valves, and the second outlet valve and pressure equalization valve are non-energized closed type solenoid valves. The purge type liquid level gauge according to item 2. 4 a differential pressure detector that detects a fluid pressure difference, a first purge pipe connected to the high pressure side of this differential pressure detector, and a second purge pipe connected to the low pressure side of this differential pressure detector, A pressure equalizing pipe connecting the first purge pipe and the second purge pipe, a first inlet valve provided on the upstream side of the first purge pipe, a first outlet valve provided on the downstream side of the first purge pipe, and the second purge pipe. In a purge type liquid level gauge comprising a second inlet valve provided on the upstream side of the purge pipe, a second outlet valve provided on the downstream side, and a pressure equalization valve provided on the pressure equalization pipe, the first
The inlet valve, first outlet valve, second outlet valve, and pressure equalization valve include
A remotely controllable valve opening/closing device is provided, and the valve opening/closing device includes a remotely controllable rotary drive device and a plurality of cams fixed to a rotating shaft connected to the rotary drive device. A purge type system characterized in that a system of a valve, a first outlet valve, a second inlet valve, a second outlet valve, and a pressure equalization valve is in contact with the cam, and the valves are opened and closed by following the rotation of the cam. Liquid level indicator.