Compressed air flow meter is a special flow meter for measuring compressed air. Compressed air flow meter is a special flow meter for measuring compressed air. Compressed air is an important secondary energy source for enterprises and enterprises. Most of them are converted from electric energy or thermal energy through compressor. When the air pressure value is lower, it is generated by the blower. The main purpose of the measurement of compressed air flow meters is to manage the working fluids converted from a large amount of energy to receive energy saving and improve the level of equipment management.
In the chemical production process, there is an important process oxidation reaction, which uses air as a raw material and another chemical reaction under certain conditions. Excessive and undersized air mass flow will have a critical impact on safe production, product quality and the consumption of valuable raw materials. In this case, the accuracy of the air flow measurement is particularly high, and most of them are also equipped with automatic adjustment.
The combustion process in boilers and various industrial furnaces is also an oxidation reaction. The measurement of the combustion air flow rate, although the accuracy requirements are not as high as the oxidation reaction in chemical production, but for environmental protection and economic combustion, fuel economy It also has important significance.
1, the vibration is large. Not every air flow meter is installed in a place with high vibration. However, air flow meters installed in compression plants and blower rooms must consider vibration problems. This vibration is mainly from the compressor and the blower, and the vibration of the machine can be transmitted to a long distance through the air duct or duct. Among them, the reciprocating compressor with the largest vibration is the vibration generated by the large reciprocating compressor during operation, which often causes the plant to vibrate together with the surrounding ground, posing a threat to the accurate and reliable operation of the relevant air flow meter. It triggers the fulcrum movement of the lever differential pressure transmitter to cause the instrument to exhibit an indication drift. The vibration causes the vortex flow sensor to generate an interference signal corresponding to the vibration frequency, causing the flow indication to be significantly higher.
2, the gas with water. The compressed air flow meter is taken from the atmosphere, which always contains a certain amount of water vapor. The content of water vapor is expressed by a partial pressure of water ps. The saturated partial pressure of water vapor in the atmosphere is a function of atmospheric temperature (see Table 3.4). In rainy and foggy days, the partial pressure of water vapor in the outdoor atmosphere reaches saturation level, that is, the relative humidity reaches 100%. At this time, the compression of the atmosphere is like a sponge that compresses the water. As the volume shrinks, there is a corresponding amount. Water is precipitated. This is a simple principle of compressing air so that it carries water. In fine weather, the relative humidity of the atmosphere is low, but as it is compressed and the volume is reduced to a fraction of the original, the partial pressure of water vapor will increase accordingly, and it may also enter a saturated state to precipitate water droplets.
The larger-diameter orifice flowmeter used to measure the flow of compressed air often has water in front of the orifice plate, which affects the measurement accuracy. There is often a period of water in the pressure line, which causes the differential pressure measured by the differential pressure transmitter to be inconsistent with the differential pressure generated by the throttling device. These are common causes of errors caused by airborne water. In addition, due to the high content of nitrogen oxides in the urban atmosphere, the water droplets contained in the compressed air are acidic, causing corrosion of the surface of the ring chamber and corrosion of the inner wall of the pipe, making the surface rough. When the iron oxide produced by the corrosion becomes dry under certain conditions, it is easy to fall off from the inner wall of the tube and be carried by the airflow to the orifice plate, which also affects the flow rate indication. Therefore, these powdery and blocky garbage should be removed during parking inspection.
3, pulsating flow. Most of the compressor and blower outlet fluids contain a certain amount of pulsation. For example, a reciprocating compressor exhibits a half-wave pulsation. At the site, it is observed that the outlet pressure of the compressor and the blower has a significant swing. Among them, the positive (fixed) displacement blower outlet pulsation frequency is relatively high, generally several tens of hertz, while the reciprocating compressor outlet pulsation frequency is low, generally a few hertz. Flow amputation causes differential pressure flowmeters, vortex flowmeters and other flowmeters to display high values, causing the floats in the float-type flowmeter to jump up and down. There are two common methods to eliminate and attenuate the influence of flow artery motion on the flowmeter value. One is to set a buffer tank to filter the pulsation at the compressor outlet, and install the flowmeter behind the buffer. In fact, the system of the reciprocating compressor is designed in this way; the second is to install the flowmeter away from the pulsation source, so that the gas volume of the process pipe and the pipe resistance constitute a low-pass filter attenuation pulsation.
Huajiang Automation can provide you with the most professional compressed air flowmeter selection recommendations and the most reliable instrument products. If you have any questions, we will have professional technicians to help you answer and hope to bring you help!
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