CN1068430C - Self-correcting supersonic level gauge - Google Patents

Abstract

The present invention relates to an ultrasonic measurement device for the rod position of a reactor control rod and the liquid levels of liquid media in different working conditions. The present invention is characterized in that a reflecting ring is arranged in an ultrasonic measurement pipe. The present invention has the advantages of simple structure and low cost. Besides, the present invention is easy to popularize to measure the rob positions of control rods of various reactors and the liquid levels of liquid media in various working conditions.

Description

Self-calibrating ultrasonic liquid level measuring device

The invention relates to the technology of measuring the rod position of the reactor control rod and the liquid level of the liquid medium under various working conditions by using ultrasonic waves.

Using ultrasonic technology to measure the liquid level of liquid medium and the material level in it, such as the position of reactor control rod, the biggest problem is that the propagation speed of ultrasonic wave in liquid medium changes with temperature, which will cause the error of ultrasonic liquid level measurement indication. In the rod position measurement of the control rod of the 5 MW heating reactor of Tsinghua University, the Chinese patent CN90100692.0 is adopted. This patent sets a known reflective surface at a fixed distance from the ultrasonic transducer, and the ultrasonic transducer The time difference between the acoustic pulse emitted by the transducer and the reflected pulse of the fixed surface is used to obtain the actual sound velocity under actual working conditions, and this sound velocity is used to correct the entire measurement system, but this requires adding a standard pulse signal to the system ultrasonic transducer. In the actual use of the project, it will appear too cumbersome, resulting in complicated operation and poor economy, so its application is greatly limited. Chinese patent CN90209099.2 is a sonar liquid level gauge. To measure the liquid level of different types and different temperatures of liquids using this liquid level gauge, in addition to installing an ultrasonic transmitting and receiving probe, another calibrator must be installed at the same time. The probe should be calibrated before each use of the liquid level gauge. The structure of this patent is complex and the operation is cumbersome.

The object of the present invention is to provide an ultrasonic liquid level measuring device with a composite structure, so that one ultrasonic probe can provide two kinds of reflected pulse signals, ie standard pulse signal and measurement pulse signal. Without any correction, it can measure the liquid level of the liquid medium in various working conditions and the material level in it, especially the rod level of the reactor control rod.

The invention consists of an ultrasonic measuring tube and an ultrasonic transducer, and is characterized in that a fixed reflective ring is arranged in the measuring tube, and the material of the reflective ring should be a metal material resistant to the corrosion of the measured liquid medium.

The ultrasonic transducer is integrated with the measuring tube by welding, and the transducer is installed on the bottom or upper part of the measuring tube; in the measuring tube, a fixed reflector is set at a known distance Lo from the reflective surface of the transducer. Ring, a small part of the ultrasound emitted by the ultrasonic transducer is reflected back by the reflection ring; while most of it goes on to meet the reflector preset in the measurement liquid, and after reflection, most of it passes through the reflection ring and returns to the To the transducer, the speed of sound can be obtained using the following relationship.

$\mathrm{<span\; class="notranslate">\; \&upsi;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}$

Then use T to get: $\frac{\mathrm{\&upsi;T}}{2}=L$ Right now $L=\frac{{\mathrm{TL}}_o}{T_o}$ The meanings of L _o , L, T _o , and T in the formula are shown in the accompanying drawings.

The ultrasonic transducer can also adopt Chinese patent CN87204877. That is, high temperature and radiation resistant fully sealed three-chip ultrasonic transducer.

The advantage of the present invention is that only one ultrasonic probe can provide two kinds of signals, that is, the standard pulse signal and the measurement pulse signal, without increasing the number of transducers, and can measure various working conditions only with a slight change in the subsequent signal processing The liquid level of a liquid medium and the material level in it. Using the invention, the measurement system is not affected by temperature changes and different media, and can be applied to the measurement of liquid level and control rod position in nuclear reactors.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

1 ultrasonic transducer;

2 Ultrasonic measuring tube;

3 reflective rings;

4 The reflector in the measured liquid;

L _o is the distance between the reflection ring and the reflection surface of the ultrasonic transducer;

L is the distance between the reflector in the measured liquid surface and the ultrasonic transducer.

Figure 2 shows the relationship between ultrasonic pulses and time.

5 transmit pulses;

6 standard pulses;

7 measuring pulse;

T _o time interval between the transmitted pulse and the standard pulse;

T is the time interval between the transmitting pulse and the measuring pulse of the reflector in the measured liquid.

Example:

In this embodiment, the ultrasonic measuring tube is made of ICr18Ni 19Ti stainless steel. The ultrasonic transducer is installed on the upper part of the measuring tube. The distance between the fixed reflection ring and the reflecting surface of the ultrasonic transducer is 500 mm. The distance of the reflective surface of the transducer is 500-10500 mm, the outer diameter of the fixed reflective ring is 45 mm, the inner diameter is 39 mm, and the thickness is 5 mm. Measuring the liquid level of petroleum products is easy to operate.

Using the present invention, when measuring the liquid level or the level in the liquid, it is not affected by temperature changes, nor is it affected by different media, and the number of its transducers does not increase, only in the subsequent signal With a slight change in the software during processing, the liquid level of the liquid medium or the level of matter in the liquid medium can be accurately measured.

The invention can be widely applied to measuring the liquid level of liquid medium in various working conditions in industry, such as petroleum, acid, alkali, salt and liquids with different viscosities, and also has practical value for measuring the rod position of reactor control rods.

Claims (1)

1. A liquid level measuring device composed of an ultrasonic measuring tube and an ultrasonic transducer, characterized in that an ultrasonic transducer probe is used to provide a standard pulse signal and a measurement pulse signal. The above-mentioned ultrasonic transducer is connected to the measuring tube by welding In one body, the transducer is installed on the bottom or upper part of the measuring tube, and a fixed reflection ring is set in the measuring tube at a position where the distance from the reflecting surface of the transducer is Lo, and a small part of the ultrasonic waves emitted by the ultrasonic transducer is reflected by the ring It is reflected back, and most of it goes on to meet the reflector preset in the liquid. After being reflected, most of it passes through the reflective ring and returns to the transducer.

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