外文翻译液位检测.docx

1、外文翻译液位检测附录CLiquid Level MeasurementChemical industry with the progress of science and technology got rapid development, in order to make the equipment safe and reliable operation, and can be utmost to improve product quantity and quality, to effectively operate automatically and process adjustment,

2、realize the scientific management for the enterprise to provide the necessary material and energy of accurate data, must be in production in the process of pressure, flow, level, temperature, chemical composition of various parameters such as timely, accurate measurement.Generally the process of con

3、tainers, tanks, towers, tank of liquid surface position level, slot bucket, cans, and warehouse ChuFa solid block, the accumulation of particles, powder height and surface position is called a material level; Two not fluid boundary between the height and the liquid and solid separation height is cal

4、led interface position, the position of assembly level, material level, liquid level interface.Material level measurement to correctly measure the container storage capacity or quality, know container level of high and low and adjust at any time, in the material level to maintain the required height

5、.Material level measurement in chemical process, not only under normal temperature, atmospheric pressure and ordinary medium, material level, liquid level measurement of the interface, but also often meet high temperature, low temperature, high pressure, inflammable and explosive (negative temperatu

6、re). Viscosity and foam, boiling dielectric material level measurement problems.In order to adapt to the characteristics of chemical objects, to meet the requirements of the chemical process material level measurement, there are many material level measurement and instrumentation.1. Ultrasonic liqui

7、d level meter and radar material level meter(1) ultrasonic liquid level meterMaterial level measurement process, the ultrasonic signal, issued by the ultrasonic probe, the liquid or solid material surface after launch back, by the same sensor receiving, ultrasonic measurement of the whole running ti

8、me, so as to realize the measurement of material level, acoustic velocity transmission of the ultrasonic pulse, from transmitting to receiving to ultrasonic pulse need time interval and the transducer to the surface of the measured medium is proportional to the distance.Emit ultrasonic level meter p

9、ulse, not the echo of detection at the same time. Due to the launch of the ultrasonic pulse width has a certain time, and after launch the ultrasonic sensor and aftershocks, during cannot detect the echo, so from the start down the surface of the probe a short distance cant normal inspection, this d

10、istance is called blind spots. Was the highest level such as into the blind area, detect instrument will not be able to correctly, there will be error, if necessary, heightened level meter can be installed.Ultrasonic liquid level meter also has shortcomings, the ultrasonic transmission by gas interf

11、erence, level surface bubbles, corrugated, etc, the ultrasonic transmission by gas interference, level surface bubbles, corrugated, etc., the ultrasonic reflection effect. Material is volatile, liquid gas entrapment, the container by vibration (e.g., motors) are installed on the container cant use u

12、ltrasonic liquid level meter.(2) radar material level meterRadar level gauge USES launch - reflection - receive work mode. Radar level meter antenna emit electromagnetic wave, the wave reflected by the measured object surface, again by the antenna, the electromagnetic wave from transmitting to recei

13、ving time is proportional to the distance to the liquid surface. In practice, there are two kinds of radar level gauge means the frequency modulation continuous wave and pulse wave. Liquid level meter adopts frequency modulation wave technology, power consumption is big, the four wire system, should

14、 be used in electronic circuit is complicated. And the radar pulse wave technology level gauge, low power consumption, easy to implement essential safety, high precision, wider application scope.Radar level gauge measuring the electromagnetic waves can pass through a vacuum, dont need a transmission

15、 medium, is not affected by air, steam, groove volatile fog effect, can be used for such as coarse benzene volatile medium level measurement.Radar level meter can be used for almost all of the liquid level measurement. Electromagnetic wave on the surface level when firing, signal attenuation, when t

16、he signal attenuation through the hours, can lead to radar level meter cannot detect enough electromagnetic wave signal, the conductive medium can be a very good reflection of electromagnetic wave, the dielectric constant is greater than 1.5 non conductive medium dielectric constant was 1.0 (air) wi

17、ll also be able to guarantee sufficient reflection wave, dielectric constant, the greater the reflection signal. In practice, almost all medium can reflect enough of reflection wave.(3) radar level gauge, ultrasonic liquid level meterUltrasound and radar is the main measuring principle is different,

18、 lead to their different application occasions, radar is given that the dielectric constant of the measured substance, which is given that the density of the material being measured, so the low dielectric constant material radar measurements will be effect to sell at a discount greatly, the solid ma

19、tter in general, push harder, another wave of different means of transmission components, such as ultrasonic wave was launched by the vibration of the piezoelectric material, so it is can be used in higher pressure or negative pressure of the situation, usually only in the atmospheric pressure conta

20、iners. The radar can be used in the process of high pressure tank. Radar emission Angle is bigger than ultrasound, small containers or elongated dont recommend using non-contact radar, generally recommend a director radar. Finally is the temperature on the accuracy, of course, must be higher than th

21、e ultrasonic, radar must use high resolution radar in the tank, without ultrasonic. As for the price, usually ultrasonic, lower than the radar in a wide range of course some ultrasonic price is also high. Such as the range of 6-70 meters, the preferred ultrasonic liquid level meter. Pay attention to

22、 the stirring groove, groove wall adhesion can produce interference of the reflected wave, level measurement, the installation is to choose the appropriate installation position, so as to avoid the interference of these factors.Level two categories, including liquid level and material level. Liquid

23、level and liquid level indicator and two continuous level measurement. Liquid level indicator is the level of several fixed position measuring, used in liquid level of upper and lower limit alarm, etc. Continuous level measurement is to measure liquid level continuously, it is widely used in many fi

24、elds such as petroleum, chemical industry, food processing, have very important significance. For more than 20 kinds of continuous level measurement method for comparative analysis. Glass tube, glass plate, double color water method.Manual gauging glass tube method: this method is using the principl

25、e of communicating vessels, level scale read directly from the instructions. Glass plate method: glass which can be installed through connectors can also be installed in the container wall openings, and series a few piece of glass to increase the range. Numerical scale read directly from the glass p

26、late level.Double color gauge method: this method using the optical principle, make water shows green, and make the water vapor shows red, which indicate the water level.Artificial gauging method: the method is used for measuring oil tank liquid level. When measuring, the surveyor gauge Surveyor to

27、volume of the oil dipstick into oil, and filed when feet lead contact with the tank bottom oil dipstick. According to the quantity of oil traces on the oil dipstick, read out the oil level height; End according to the quantity of oil dipstick test cream color change to determine the height of the wa

28、ter cushion layer, to determine high oil and high water above 4 methods are artificial measurement method, measurement is simple, the advantages of high reliability, intuitive, and low cost.Blowing method, differential method, HTG blowing method: because of the blow pipe approximation is equal to th

29、e fluid column pressure in the static pressure, thus P = rho gH type of rho - liquid density; H - level. So the liquid level is measured by the static pressure P can be H. Strong method suitable for measuring the corrosive gas blowing, have suspended material content in the liquid, and is mainly use

30、d in the measurement accuracy is not high.Differential pressure method: the open container or atmospheric vessels, valves and gas phase pressure pipeline saves. Based on the relationship between differential pressure and liquid level P = P2 - P1 = rho gH type: P - positive and negative pressure cham

31、ber pressure transmitter; P2 and P1 - led tube pressure; H - level. Differential pressure transmitter will pressure difference transformation for 4 20 mA dc signal. If the pressure in the measuring range lower limit of the corresponding output signal is greater than or less than 4 mA, are all need t

32、o adjust the migration zero migration technology such as spring, is equal to 4 mA. HTG method: this method is applied to differential pressure oil tank liquid level measurement.Buoy method: this method USES the middle maglev barrel with holes as liquid level sensor. Stainless steel casing from buoy

33、hole through the middle, between fixed to the roof and bottom. Liquid level change driven maglev hollow tube (permanent magnet) hides inside can move up and down the casing, and attract the casing of magnet can move up and down the casing wall, secondary instrument | instrument according to the moving magnet volume to calculate the liquid