JPS60196641A - Gas leakage detector of accumulator - Google Patents

Abstract

PURPOSE:To check the gas leakage with an accumulator being connected to a hydraulic system, by measuring the interval between the end wall of a tightly closed chamber and a piston by an ultrasonic wave sensor, performing temperature correction, computing the gas pressure, and comparing the result with the signal of a pressure sensor. CONSTITUTION:In a main body 2 of an accumulator 1, an upper tightly closed chamber 7 and a lower comminucating chamber 13 are formed by a piston 5. Ultrasonic waves are transmitted to the piston 5 by an ultrasonic wave sensor 5. The reflected waves are received and amplified by an amplifier 28. The time signal from a time command circuit 34 is converted into a pressure signal by a time to voltage converter 31. Meanwhile, temperature correction of the signal from a temperature sensor 23 is performed by a temperature correction converter 32, and the result is inputted to a comparator 36. On the other hand, the signal from a pressure sensor 18 is also inputted to the comparator 36. When the gas leakage is detected, the output signal is outputted to an alarm 37.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an accumulator used in a hydraulic power generation device in a thermal power plant or a nuclear power plant, and particularly relates to a gas accumulator for detecting gas leakage from an accumulator. The present invention relates to a leakage detection device.

[Technical background of the invention]

The turbine of the power plant described above is provided with a hydraulic pressure generator for lubricating bearings of the turbine and driving control valves and the like. This oil pressure generator, especially the oil pressure generator for driving control valves, is concerned with the amount of hydraulic oil required during normal operation.
``!A large amount of hydraulic oil is required when a steam control valve or the like makes a transient movement.For this reason, an accumulator is generally attached to the hydraulic pressure generator, and during the above-mentioned transient movement, the accumulator is used as an accumulator. The system discharges the hydraulic oil that has been generated and supplies the necessary hydraulic oil.First, a general accumulator used in a hydraulic pressure generator is shown in Fig. 1.
L7. I will clarify.

The steel cylindrical body 2 of the accumulator 1 has both end walls 3, 4
The main body 2 is sealed, and a piston 5 having a piston ring 6 mounted thereon is slidably disposed within the main body 2. An upper chamber 7, which is a sealed chamber within the main body 2 and partitioned by the piston 5, is filled with nitrogen gas via a gas-charged pulp 8 provided on the end wall 3.

On the other hand, a branch pipe 11 branched from a pipe 10 equipped with a pump 9 for generating hydraulic pressure that supplies hydraulic oil in the direction of the arrow serves as a communication chamber of the main body 2 via a boat 12 formed on the end wall 4. It communicates with the lower chamber 13. An on-off valve 14 is interposed in this branch pipe line 11, and a drain pipe line 15 in which a drain valve 16 is interposed is connected to the branch pipe line 11 between this on-off valve 14 and the boat 12. ing. Note that a check valve 17 is interposed in the pipe line 10 upstream from the connection position of the branch pipe line 11.

According to the above-mentioned configuration, during normal operation, the pressure of the hydraulic oil in the pipe line 10 is maintained at a certain constant value by the pump 9, and the nitrogen gas in the upper chamber 7 of the accumulator body 2 is compressed and pushed into the piston. 5 rises to the upper side, and the silicon gas pressure
It is equal to the hydraulic oil pressure within 0. Now, if the steam control valve of a steam turbine performs a transient operation and requires a large amount of hydraulic oil, or if the pump 9 stops, the pressure of the hydraulic oil in the pipe 10 will decrease, but the pressure Nitrogen gas in the upper chamber 7 of the accumulator 1 expands to the extent that the amount decreases, pushing down the piston 5 and releasing the hydraulic oil accumulated in the lower chamber 13 into the branch pipe 11 and into the pipe 10. works to prevent pressure drop. On the other hand, the accumulator 1 also functions to absorb the pulsation of the hydraulic oil generated from the pump 9. Therefore, in order for the accumulator 1 to perform its functions, the upper chamber 7 of the accumulator 1 must always be filled with a specified amount of nitrogen gas.

[Problems with background technology]

The nitrogen gas pressure inside the accumulator 1 can be measured by attaching a pressure gauge (not shown) to the charge nozzle 8 for filling nitrogen gas provided on the upper wall 3 of the main body 2.
The pressure in the upper chamber 7 is always equal to the pressure of the hydraulic oil in the pipe line 10 during normal operation, so even if nitrogen gas in the upper chamber 7 leaks for some reason, the piston 5 will not be connected to the accumulator. 1, the nitrogen gas pressure is always the same as in the pipe 10, and therefore, even if the nitrogen gas pressure is detected, it is not possible to check for gas leakage. Therefore, if the accumulator 1 is used with the nitrogen gas leaking, even if a transient amount of oil is required, the accumulator 1 will not be able to release enough required hydraulic oil.

During normal operation, if nitrogen gas leaks from the accumulator 1, the piston 5 will rise, so if 50 strokes of the piston can be detected, it is possible to determine whether nitrogen gas has leaked.
When high-pressure hydraulic oil of about Kp, 6+t g- is supplied, the accumulator main body 2 becomes a high-pressure pressure vessel υ, and the wall thickness of the main body 2 is also thick, making it impossible to easily detect the piston position. Therefore, the charge of accumulator 1, 11
11 In order to check the filling amount of nitrogen gas, either stop the ponzo 9 to lower the pressure in the line 10 and detect the nitrogen gas pressure inside the accumulator 1, or check the accumulator body 2 and the line 10. Filling of nitrogen gas is performed by closing the on-off valve 14 divided into the branch pipe 11 between the two, opening the drain valve 16 to release the hydraulic oil accumulated in the accumulator 1, and detecting the pressure of nitrogen gas. Checking the status.

As explained above, in the conventional accumulator 1, when detecting the filling nitrogen gas pressure in the accumulator 1, the pump 9 is stopped or the accumulator 1
This must be done by closing the on-off valve 14 of the branch pipe 11 to the hydraulic oil system, but in the case of a pump 9 used in continuous operation such as in a steam turbine power generation facility, the pump 9 cannot be stopped. Further, when the on-off valve 14 to the accumulator 1 is closed and disconnected, another accumulator of the same capacity is required as a backup.

[Purpose of the invention]

This invention eliminates the drawbacks of the conventional systems described above, detects the state of nitrogen gas filled in the accumulator without disconnecting the accumulator from the hydraulic system during operation of the hydraulic generator, and detects leakage. An object of the present invention is to provide a gas leak detection device for an accumulator that can raise the reliability by being able to issue an alarm.

[Summary of the invention]

This invention relates to an ultrasonic sensor that measures the distance between the end wall of a sealed chamber and a piston, a temperature sensor that measures the temperature and pressure inside the sealed chamber, and a temperature correction conversion device that corrects the temperature of the output signal of the ultrasonic sensor. a function generator that calculates the gas pressure 'ff: by the output signal of the temperature correction converter, a comparator that compares the output signals of this function generator and the pressure sensor, and an alarm connected to this comparator. It is characterized by having the following.

[Embodiments of the invention]

The present invention will be explained below with reference to embodiments shown in the drawings. Components that are the same as those shown in FIG. 1 described above are designated by the same reference numerals in the drawings, and their explanations will be omitted.

In FIG. 2, a gas charge valve 8 is attached to the earth wall 3 of the main body 2 of the accumulator 1 at the center thereof, and a pressure sensor 18 is attached to the gas charge valve 8.
is installed. Further, a pair of through holes 19 and 20 are bored on the diameter line of this upper wall 3. this house,
An ultrasonic sensor 21 for measuring the distance from the upper wall 3 to the piston 5'' is screwed into one of the through holes 19 through an O-ring 22, and the other through hole has an ultrasonic sensor 21 screwed therein for measuring the distance from the upper wall 3 to the piston 5''. A temperature sensor for measuring the temperature of nitrogen gas is screwed on via an O-ring.

As shown in FIG. 3, the ultrasonic sensor 21 is supplied with the output signal of the voltage signal transmitter 5 via a time gate force to which a time command signal is input, and an amplifier 27. It has become. The output signal of the ultrasonic sensor 21 is input to the time/voltage converter 31 via an amplifier path, a time gate 4 into which the signal of the time command unit 34 is input, and a gain adjustment waveform converter 30. ing. A signal from the time command unit 34 is input to this time/voltage converter 31. Further, the signal from the temperature sensor n is input to an amplifier 38, and the output signal of this amplifier and the time/voltage converter 31 is input to a temperature correction converter 32. The output signal of the temperature correction converter 32 is inputted to the functional pottery 33 and is given the curve characteristic shown in FIG. Further, the output signal of the pressure sensor 18 is input to an amplifier station, and the output signal of this amplifier station and the function generator is input to a comparator 36. Therefore, when the comparator 36 detects a gas leak, the output <y is input to the alarm 37.

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

First, the voltage signal generated by the voltage signal transmitter 5 is transferred from the time signal generator 2f5 to the amplifier 2 using the pulse signal of the time command 34.
The ultrasonic sensor 210 emits an ultrasonic wave toward the piston 5, and the reflected ultrasonic wave is received by the receiving section of the ultrasonic sensor 21. The received signal is amplified by an amplifier circuit, passed through a time gate 29, converted into a waveform by a gain adjustment waveform converter (9), and further converted into a time/open command signal by a time/OL pressure converter 31. The time signal is converted into a voltage signal by converting the time signal into a voltage signal, and on the other hand, the voltage signal output from the temperature sensor is passed through an amplifier and subjected to temperature correction by a temperature correction converter 32 having a function as shown in FIG. The signal is passed through a function generator having the curve characteristic shown in FIG. 5, and is connected to the comparator 36 with the curve characteristic.

On the other hand, the voltage signal from the pressure sensor 18 is also connected to the comparator 36 via an amplifier. And the function generator 33
The comparator 36 compares the voltage signal from the amplifier 35 with the voltage signal from the amplifier 35, and outputs a non-output signal to the alarm 37 in the event of gas leakage.

This measurement method uses the ultrasonic sensor 21 to emit ultrasonic waves, measures the time it takes to receive the reflected waves, and then measures the distance from the ultrasonic sensor 21 to the piston 5. The volume and pressure of the gas during use are measured and compared with the pressure when the gas is full, which is output from the pressure sensor 8.

The gas section upper chamber 7 in the accumulator 1 is partitioned by the end wall 3 and the piston 5, and the distance from the ultrasonic sensor 21 provided on the end wall 3 to the piston 5 is measured from t1 transmission to reception. When the time is t1 and the speed of sound in nitrogen gas is V, the distance t is expressed by the following equation.

t Furthermore, since the sound speed V increases in proportion to the square root of the absolute temperature, temperature correction by the temperature correction converter 32 is required.

Here, assuming that the inner diameter of the accumulator 1 is -iD, the gas volume 2 is expressed by . Furthermore, since Pv=constant according to the ideal gas theorem, the gas pressure decreases from FIG.

A comparator 36 compares the gas pressure during use with the gas pressure during filling to detect gas leakage.

Further, the reason for providing the comparator 36 is as follows.

In the event that the pressure in the pipe line 10 drops, the ultrasonic sensor 21
and the distance between piston 5 increases. Conversely, when the pressure in the conduit 10 increases, the distance between the ultrasonic sensor 21 and the piston 5 decreases. In addition, if nitrogen gas leaks,
Even if the zero pressure does not change, the gas capacity decreases, so naturally the distance between the ultrasonic sensor 21 and the piston 5 decreases. This is the gas pressure in accumulator 1 and pipe 1
This is because the pressures at zero are equal.

In other words, even if there is a decrease in the distance between the ultrasonic sensor 21 and the piston 5, it cannot be immediately determined whether this is due to gas leakage or an increase in the pressure in the conduit 10. Therefore, it is necessary to compare the pressure with the pressure in the pipe line 10. In the present invention, the pressure sensor 18 is provided in the accumulator main body 2 for compactness in consideration of the fact that the pressure in the conduit 10 is equal to the pressure in the accumulator, but it may of course be provided in the conduit 10.

Well, Figure 5 shows the curve characteristics when filled with gas, so the volume of gas when in use and the pressure sensor 18 at that time.
If the measured value of is on curve a, there is no gas leakage, but if the measurement value is on curve a,
i! It can be determined that the farther apart the measured values are from each other, the greater the gas leakage.

FIG. 6 shows another embodiment of the present invention.
If all the circuits shown in the figure except for the amplifier and sensor are implemented using mini-computers and multiple accumulators 1 are taken into consideration, the result will be as shown in this figure.

Accumulators la and lb are connected to a minicomputer 41 via amplifiers 40a and 40b. This minicomputer 41
A and E are temperature signal input ports), B and F are pressure signal input ports, C and G are ultrasonic output ports, and D and H are ultrasonic input ports. In this figure, gas leakage is detected by a minicomputer 41 using four input ports per one accumulator.

Another method for detecting gas leakage is to use only four input/output boats for multiple accumulators (1 tl); a switching circuit is installed in the input/output circuits of all accumulators 1, and the four boats are shared. Good too.

〔Effect of the invention〕

As explained above, the accumulator gas leak detection device according to the present invention includes an ultrasonic sensor that measures the distance between the end wall of the sealed chamber and the piston, and a temperature sensor and a pressure sensor that measure the temperature and pressure inside the sealed chamber. a temperature correction converter for temperature-correcting the output signal of the ultrasonic sensor; a function generator for calculating gas pressure based on the output signal of the temperature correction converter; and an output signal of the function generator and the pressure sensor. Since it has a comparator that compares the nitrogen gas and an alarm connected to this comparator, it is possible to check the state of nitrogen gas filled in the accumulator without disconnecting the accumulator from the hydraulic system while the hydraulic pressure generator is operating. It has the excellent effect of being able to be detected and improving reliability.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional explanatory diagram showing a general accumulator;
FIG. 2 is a longitudinal sectional view showing an embodiment of the accumulator gas leakage detection device Pt according to the present invention, FIG. 3 is a circuit diagram showing an electrical system outside the accumulator main body of FIG. 2, and FIG. 4 is a gas A graph showing the relationship between the velocity Vo of the sound wave inside the accumulator and the absolute temperature T. Figure 5 shows the pressure P when the accumulator is filled with gas.
FIG. 6 is an electrical system diagram showing an example of application of the present invention. ■...Accumulator, 2...Main body, End...Piston, 7...Upper chamber, 18...Pressure sensor, 21...-
Ultrasonic sensor, O... Temperature sensor, 32... Temperature correction converter, 33... Function generator, 36... Comparator,
41...Minicomputer. Applicant's agent Hisashi Hatano 3rd

Claims (1)

[Scope of Claims] 1. A sealed chamber and a communication chamber are formed by a piston that is slidable within the accumulator body, and an end wall of the sealed chamber is installed in the accumulator in which gas is sealed in the sealed chamber. and an ultrasonic sensor for measuring the distance between the pistons.
A temperature sensor and a pressure sensor that measure the temperature and pressure inside a sealed chamber, a temperature compensation converter that temperature-compensates the output signal of the ultrasonic sensor, and a function generator that calculates gas pressure using the output signal of this temperature compensation converter. a comparator for comparing the output signals of the function generator and the pressure sensor; and an alarm connected to the comparator. 2. The accumulator gas leak detection device according to claim 1, wherein the temperature correction converter, function generator, and alarm are provided in a minicomputer so that gas leaks from a plurality of accumulators can be detected simultaneously.