JPS6066121A - Ultrasonic level gauge - Google Patents

Abstract

PURPOSE:To measure a height of a liquid level in a tank with high accuracy by a simple constitution by providing plural ultrasonic transmitting and receiving probes and an in-tank ultrasonic reflecting plate opposed to said probe, in the vertical direction of the outside wall of the tank, and executing a switching operation. CONSTITUTION:A multi-channel type ultrasonic probe 24 is provided so as to be opposed to an ultrasonic reflecting plate 17, in the vertical direction of the outside wall of a tank 1, and each probe of the probe 24 is switched and connected automatically and successively to an electric pulse transmitter 15 and a receiver 16 by an automatic switching device 25, and a cryogenic temperature liquid 2, etc. are scanned at a high speed by an ultrasonic wave. According to them, a height of a liquid level in the tank is measured with a high accuracy basing on an acoustic impedance variation by a simple constitution.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention uses ultrasound to determine the height of the liquid level in the tank.

This liquid level meter uses the principle of reflection to measure the liquid level in a tank filled with cryogenic liquids such as liquid oxygen and liquid nitrogen.It is particularly suitable for ultrasonic liquid level measurement with easy and accurate measurement. It is related to the meter.

[Background of the invention]

However, when measuring the level of an extremely low-temperature liquid such as liquid oxygen or liquid nitrogen, it is impossible to draw the liquid out of the tank (it turns into scum at room temperature), so a differential pressure type liquid level is used. Meters etc. are used.

This method? : To explain with Figure 1, 1 is a tank, 2 is a cryogenic liquid such as liquid oxygen, 3 is a gas in the can such as oxygen, 4 is a cold pack L for maintaining the cryogenic temperature, 5 is a cold pack, and 6 is a cold pack. Differential pressure type liquid level gauge, 7 is the tank internal pressure conducting upper pipe, 8 is the tank internal pressure conducting upper pipe, 9 is the gas in the pipe such as oxygen, and it is output through the tank internal pressure conducting upper pipe 7 installed at the bottom of the tank l. As the cryogenic liquid 2 approaches the cold storage tank wall 4, a vaporization phenomenon occurs due to the temperature rise, and outside the cold storage tank wall 4, it becomes gas 9 in the pipe. The cryogenic liquid 2 in the tank 1 is communicated with the can gas 3 in the tank 1 through the tank internal pressure conduction upper pipe 8 that is piped from the differential pressure type liquid level gauge 6 to the tank 1. It becomes possible to display only the pressure (head pressure) corresponding to the liquid level height on the differential pressure type liquid level gauge 6, and the principle is that the liquid level can be measured indirectly by observing changes in this pressure. , this type of liquid level gauge is
Due to the need for an opening in the tank and the need for fairly long piping, consideration must be given to strength.
In addition, the manufacturing cost is high, and dust remaining in the tank 1 causes clogging of the upper pipe 7 for transmitting the internal pressure of the tank, resulting in measurement errors.

[Purpose of the invention]

The purpose of the present invention is to accurately measure the height of the liquid level in a tank using inexpensive equipment based on information obtained from the reflection of ultrasonic waves injected into the tank, and to maintain a constant liquid level. An object of the present invention is to provide an ultrasonic liquid level gauge capable of outputting signals for automatically opening and closing liquid supply valves and the like for maintaining the liquid level.

[Summary of the invention]

The present invention utilizes the principle that ultrasonic waves have the ability to pass through solids and liquids, and that if there is an obstacle with a different acoustic impedance on the propagation path, it will be reflected at the boundary surface. The height of the liquid level can be checked semi-directly from the information of reflected ultrasonic waves obtained from the attached reflector plate, which has a simple structure.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 illustrates the configuration of an embodiment of the present invention, where l is a tank, 2 is a cryogenic liquid, 3 is a gas inside the can, 4 is a wall of a cold storage tank, and 5 is a cold pack. The configuration is the same as that shown in FIG. , 10. +1. 12.13 is the emission of ultrasonic waves placed vertically on the outer wall of tank 1.

A receiving probe, 14, is a probe 10. 11.12
．． 13 is an electric signal switcher that sequentially excites 15 is an electric pulse transmitter, 16 is a receiver, 17 is an ultrasonic reflector provided inside the tank l, 18 is a mounting plate for the ultrasonic reflector 17, and beauty is an electric pulse It is.

3.4.5 is an explanatory diagram of the operation of FIG. 2.

In FIG. 3, the electric pulse field emitted from the electric pulse transmitter 15 of FIG. Ru. In this case, the liquid level in tank l is
If the ultrasonic wave 19 is located at a position lower than the installation height of the probe 19, the ultrasonic wave 19 will be reflected 100 times at the interface between the back wall of the tank 1 and the gas 3 in the can (due to the principle of sound pressure reflection), and will reach the probe 10 along the outward path. Return. On the other hand, in FIG. 4, the electric pulses emitted from the electric pulse transmitter 15 of FIG. 12 and 13 are sequentially excited to emit ultrasonic waves 19 into the wall of the tank 1. At this time, the liquid level in the tank l is the same as that of the probes 11, 12. 13, the ultrasonic waves 19 are transmitted into the cryogenic liquid 2 according to the passage rate determined by the acoustic impedance of each material at the interface between the back wall of the tank 1 and the cryogenic liquid 2. Ultrasonic waves 19 propagate. This ultrasonic wave 19 is reflected by the surface of a reflector 17 installed at a certain distance from the back of the wall of the tank l in the cryogenic liquid 2, and sequentially returns to the probe 11.12.1- along the outward path. .

FIG. 5 shows that in FIGS. 3 and ff14, the ultrasonic wave 19 reflected from the back wall of the tank 1 or the reflecting plate 17 is transmitted to the probe 10 or 11, 12. 13, the figure is displayed on the cathode ray tube built into the receiver 16 in FIG. n is the reflected waveform from the back of the wall of the tank l, and phantom is the reflected waveform from the reflector plate 17. The state is shown in Figure 5(b).
shows the state shown in FIG.

That is, in FIG. 3, there is no cryogenic liquid 2 in the tank l that is opposite to the mounting height position of the probe lO, so the
), only the reflected waveform n from the back wall of the tank 1 is displayed on the cathode ray tube, and in FIG.
12. Since the cryogenic liquid 2 is in the tank l opposite to the installation height position of 13, there is a reflection waveform n from the back wall of the tank 1 on the cathode ray tube as well as a reflection plate 1 as shown in Figure 5 (bl).
A reflected waveformer from 7 is displayed on a gate 21 set in advance on the time axis of the cathode ray tube according to the distance from the wall of the tank 1 to the reflector 17. In addition, when the liquid level is between the probes 11 and 12, the figure for the probe 10.11 becomes as shown in FIG.
Of course, the figure for 13 will be as shown in Figure 5 (-).

According to this embodiment, a plurality of probes 10 to 14, etc. and one reflector plate 17 are set within a vertical distance of a tank l where a change in the liquid level is expected, and the reflections on a cathode ray tube are set. Simply monitor the waveform or the output signal from the gate to
This has the effect that the height of the liquid level of the cryogenic liquid 2 inside can be easily measured.

FIG. 6 shows another embodiment of the present invention.
The same symbols as those in Figures 4 to 4 indicate the same parts. Sae is a multi-channel type probe in which a large number of transducers are arranged linearly and integrated; 5 is a multi-channel type probe array that electrically switches electric pulses transmitted from an electric pulse transmitter 15 at high speed. Automatic switching device, G is a controller that performs control operations based on the reflected ultrasonic signal output from the receiver 16, n is an automatic adjustment valve, public is a supply pipe, pair is a supply liquid, and an electric pulse generator. (The electric pulse (source) transmitted from the i-device 15 sequentially excites each transducer in the multi-channel type probe row by an automatic switching device, and the ultrasonic wave 19 is transmitted within the length range of the reflector 17 ( (within the liquid level measurement range) at high speed.

As explained in FIGS. 3 to 5, the height of the liquid level of the cryogenic liquid 2 can be determined by the figure on the cathode ray tube of the receiver 16, and the electric signal output at the time point of the gate 21 can be determined by the controller. , and by instructing the opening/closing amount of the automatic adjustment valve n, replenish the replenishment liquid 29?11-tank 1 through the replenishment pipe section, and bring the liquid level of the cryogenic liquid 2 to the desired height. It was designed to be kept. Therefore, it is effective to keep the liquid level of the cryogenic liquid 2 constant at all times by controlling the automatic adjustment valve 27 and the like in addition to improving the liquid level height accuracy at high speed.

〔Effect of the invention〕

According to the present invention, it is possible to instantly determine whether or not there is liquid on the inner surface of the tank corresponding to the mounting height of the probe based on the information of reflected ultrasonic waves. By arranging the probes in a straight line, the liquid level can be easily and accurately measured from the reflected ultrasonic information obtained from each probe, and the liquid level can be controlled based on the reflected ultrasonic information. By operating the system, the liquid volume can be controlled at a constant level.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing the state of use of a conventional liquid level needle;
Figure iJg2 is a longitudinal cross-sectional view showing the state of use of an embodiment of the ultrasonic liquid level meter according to the present invention, Figures 3 and 4 are partially enlarged views of the second figure showing the operating principle, and Figure 5 is a diagram showing the state of use on a cathode ray tube. FIG. 6 is a front view of the figure shown in FIG. 6, and FIG. 6 is a longitudinal section showing another embodiment. l...Tank, 2...Cryogenic liquid, 3.
...Gas inside the can, 4...Cool tank wall, 5...
...cold pack, 10. 11.12゜13...
・Probe, 14... Electric signal switch, 15...
Electrical pulse transmitter, 16...Receiver, 17.
・Curved ultrasonic reflector, 18...Mounting plate, 19...
...Ultrasonic wave, addition...Emission pulse waveform, 21
・Song/gate, n...Reflected waveform from the back wall of tank l, n...Reflected waveform from reflector 17,
Sae...Multi-channel type probe, Anger...
...Automatic switch, Immersion...Controller, 4...
... Automatic adjustment valve, 3... Supply pipe, 4...
...Replenishment fluid, addition...Electric pulse Fig. 1 Fig. 3 Fig. 4

Claims (1)

[Claims] 1. A plurality of ultrasonic wave emitting and receiving probes are arranged vertically on the outer wall of the tank, and an ultrasonic reflector is arranged on the inner surface of the tank opposite to the height thereof, An ultrasonic liquid level gauge characterized in that a pulse transmitter and a receiver are connected to the ultrasonic wave generation and reception probe via a switch. 2. The ultrasonic liquid level gauge according to claim 1, which is an automatic changeover, and the automatic adjustment valve for replenishment liquid is connected to a receiver via a controller.