The various types of flowmeters feature comparison table
Published on：2015-11-10 9:49:15 Hits：
When it comes to high-temperature fluids, it does not give a definition of the meaning clear high temperature range. At present, the industrial measurement instruments, different types, both self-imposed the respective temperature range. For example: a thermometer in the range of 1500 ~ 2000 ℃ temperature range, the control valve, the switching valves and other valves, when it comes to high temperatures, means more than 400 ~ 500 ℃ temperature. Meter structure also according to different principles and provisions of the different ways a high temperature range. Now practical industrial temperature limit for differential pressure flow throttle mechanism is about 540 ℃, volumetric flowmeter is about 200 ℃, area flow meter is about 400 ℃.
The need to measure, but in typical high temperature fluid measuring some problems, we list the following three. As a medium or high temperature gas thermal energy, high-temperature steam, fast breeder reactors, the strong thermal coal quality - liquid metal sodium; iron and steel industry in the iron, steel. Is this three fluids, for different accuracy and use of materials, the main points in the measured flow requirements were also different from the general common narrative it is difficult. Therefore, this chapter only practical problem of high temperature gas, high temperature steam orifice flowmeter is used to measure the liquid metal and electromagnetic flowmeter be described as the center of the high temperature fluid flow measurement.
For the method of hot metal, molten steel flow measuring there are two: one is the application of high-frequency skin effect of the cross-sectional area of the flow channel measurement mode; the other is the way electromagnetic flowmeter. Both methods can be used in continuous steel-making equipment. To be able to carry out direct, non-contact form of measurement, also carried out extensive research and discussion, but, in fact, generally through the traffic in terms of height or weight of the liquid column batch processing. Therefore, this chapter without narrative. In addition, when the liquid metal sodium flow measurement, test the detector is installed in a pipe outside the ultrasonic way, it will soon be practical, where the same without narration.
Measuring the flow rate of the high temperature fluid with the throttle mechanism
Application examples of various devices
Use high temperature fluid to the power sector, iron and steel, chemical industries, the scope is very wide, they are to deal with various types of fluids. When carrying out measurement of liquid, steam, gas and other traffic, people from a variety of different types of structural principle of the flowmeter, the first study of differential pressure flow throttle mechanism is applicable, in fact, apply most. This is because of its simple structure, but also has a wealth of data and actual experience. As a result, the throttle device as process instrumentation, its credibility than any other instruments are the subject of attention.
Power generation and power plant business with each plant with high efficiency and large capacity as the goal, the steam temperature and pressure of the boiler up to the critical temperature and pressure. This high temperature steam, high pressure superheated steam, its temperature reaches 568 ℃, pressure up to 240 kgf / cm 2. The flow of high-pressure steam from the boiler turbine flow nozzles and other general use to measure the throttle device.
In steel, iron, and will raise the temperature of the combustion air and then blown into the blast furnace, converter, sintering furnace and other furnace. The combustion air flow measurement throttling device available Venturi tubes. In addition, the exhaust gases from the furnace are also a high temperature range, can measure the flow Venturi tube.
Since the exhaust gas is high-temperature gas, which is corrosive and contain dust, in the selection of materials, to consider these characteristics and conditions of use, use in line with the intended use, the corrosion resistance of the material.
In the chemical, petrochemical industry, for example: hydrogen plant, by steam reforming law reformer furnace, the temperature inside the reaction tube also add about 800-900 ℃. Contacting the modified device petroleum refining. Temperature of 420 ~ 580 ℃, pressure of 15--50 kgf / cm 2. These devices, although the temperature is a high temperature furnace, but is to measure and control the flow rate into the furnace before, so. Then the temperature of the fluid without measuring.
More than merely cite a few examples. High temperature fluid to be measured are still many, many others.
When considering the flow measured with a high temperature fluid throttle device, and select the valve-like material, as in the importance of paying particular attention should be paid temperature stress.
Select the appropriate materials, high temperature range can be measured flow. But from the point of view on the material strength, tensile strength, yield point decreases with increasing temperature, when reached about 400 ℃ above, it appeared creep phenomenon, and therefore, this temperature is regarded as the highest temperature of the throttle device . The following items in this range use must pay attention to narrative.
Construction on the throttle device has been described in detail, here only describes matters should pay particular attention.
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