The application of ultrasonic level meter measuring liquid level in the industry
Ultrasonic level meter is also called ultrasonic liquid level meter, ultrasonic level meter, ultrasonic level meter, it is a good a militant interface measurement, in industry, for liquid level measurement is widely used in applicable to petroleum, chemical industry, water, sewage treatment, industrial control, steel, coal, hydrological and hydroelectric power, food processing industries, etc. With the deepening of the degree of industrialization, more and more strict with the precision of level measurement. In order to achieve design than in a wide range of ultrasonic level meter, control of liquid level measurement and a more precise, in all kinds of different methods of measuring liquid level gauge chose the ultrasonic measurement, the method can achieve low cost high precision measurement. She installation is simple, applicable widely, the price is low, is cheap and fine level, level measurement.
Petroleum chemical engineering department are generally large storage tanks, small level measurement error will cause a lot of absolute volume error, and improve the precision of level measurement, not only the degree of measuring has very important significance of oil tanks, in other liquid level measurement system, also in a more and more important position. Henan cisco reversible measurement and control technology co., LTD., in the traditional piezoelectric transducer as the core of the ultrasonic testing technology, combined with advanced integrated circuit technology and computer technology. This not only greatly improve the accuracy of the traditional ultrasonic testing technology, and improved the stability and reliability.
In practical industrial applications, the liquid level measurement has the following features:
(1) surface is horizontal, but when there are material flow into or out liquid level there will be waves;
(2) in some process liquid will boil or foaming;
(3) a large container will appear everywhere temperature, density and viscosity of uneven;
(4) some of the liquid level in a number of of kilos per square centimeters force flows on a bet or high temperature; Some big media viscosity; Some contain a large amount of impurity and suspended matter.
Installation level measurement device and the relationship between the measured medium, liquid level meter can be divided into contact and non-contact, contact level gauge are simple structure, so the application more widely, and medium on the level of work performance implications, the contact liquid level meter is mainly include the following:
(1) direct reading type liquid level measurement, there are mainly glass tube liquid level meter, using the connectivity principle, directly read the liquid level of the liquid in the container medium;
(2) the differential pressure type liquid level measurement, mainly include pressure pipe and flange type level gauge, using the characteristics of a certain quality of liquid pressure to on the contrary liquid level;
(3) the buoyancy type liquid measurement, tired instrument testing part is to use the float to float on the surface of the liquid, or the sinking of the immersed in liquid form.
But contact the level due to contact with the medium in the measurement process, the inevitable to the pollution caused by the measured medium, this cannot bear certain areas or in industry.
The non-contact liquid level meter now basically has the following kinds:
(1) laser, by using laser direct good advantages for distance measurement, the speed of light is very large, the signal processing part of the requirements for the liquid level meter is too high, not suitable for level measurement of short distance;
(2) the radar type, using the reflection of electromagnetic wave in measuring liquid surface medium, take time to calculate liquid level value by judgment, radar type level gauge is very strict to the requirement of the product installation, and the price is higher;
(3) ultrasonic type, the use of ultrasound in the air to good advantage, using the ultrasonic time difference from the launch to accept to calculate liquid level.
Ultrasonic wave in the medium such as reflection, refraction, diffraction, scattering and spread rule, and the rule of audible sound waves there is essentially no difference between. But the very short wave lengths of ultrasound make only a few centimeters, even several millimeters per thousand. Compared with audible sound waves, ultrasonic has many significant characteristics: propagation characteristics - the very short wave lengths of ultrasound make usually the size of the obstacles to a lot of times larger than the wavelength of ultrasonic, ultrasonic diffraction ability is very poor, therefore, it can in a homogeneous medium directional line, the shorter the wavelength of ultrasound, this feature is more significant, ultrasonic level meter formal use of the characteristics of ultrasonic.
Ultrasonic liquid level meter is the fastest growing a contact measurement, the technology is based on the ultrasonic velocity in air and surfaces meet bai testing can produce the principle of reflection, the realization of the measurement of domestic is not affected by medium density, viscosity, can achieve wide measurement range. At present, the domestic ultrasonic liquid level meter and there are large gaps when compared with foreign products, mainly reflected in the level of the blind area on the distance and range accuracy, domestic ultrasonic liquid level meter of blind area in 0.3 ~ 0.6 m, roughly 0.25 ` 0.5% accuracy; Foreign ultrasonic level meter blind area generally is 0.25 m, about 0.15% accuracy.
Ultrasonic level meter installation and upper container, under the control of the electronic unit, probe to launch a bunch of ultrasonic pulse object to be tested, acoustic bai surface reflection, part of the echo by the probe to accept and converted to electrical signals, from ultrasonic launch to be accepted, the time and the probe is proportional to the distance of the object to be tested.
Install generally have flange and thread in two ways. When installed, want to consider the influence of blind area commonly, we want to ensure the highest level in the house to the distance is greater than the blind spots on the surface of the probe. Who avoid blind area, with extension tube installation, must pay attention to probe both of radiating surface side and the catheter end end of than turn Angle to the sharpness of the Angle.
Above, this paper introduces the principle of ultrasonic liquid level meter, the main problem such as technology, on-site installation, ultrasonic level meter is a kind of widely used, the fine of militant interface measurement. In water treatment, chemical industry, metallurgy, electric power, water conservancy and other fields applied GuanFan, each product has advantages and disadvantages, should try to avoid the disadvantages in the process of actual use, use of advantages, to play the biggest role.