Flowmeter selection description

It is safe and reliable in flow measurement. First, the measuring instrument will not affect the safety of the production system under normal production or fault conditions. The second is the reliability of the measurement method, that is, the sampling device does not cause mechanical strength or electrical circuit failure during operation, causing an accident; for example, the measurement of the high-temperature and high-pressure main steam flow of the power plant, the primary measuring component installed in the pipeline Must be strong to ensure no mechanical damage under high-speed steam scouring. Therefore, it is generally preferred to use a standard throttling device instead of a non-standard tachometer such as a cantilever beam double horn tube or a plug-in flow meter, and a target type, a turbine flow meter, etc. having a low structural strength. Explosion-proof instruments should be used for fuel-fired power plants and where flammable gases are available.

The main steam flow measurement of power plants, due to its importance to the safety and economy of power plants, generally adopts a mature standard throttling capacity with differential pressure flowmeter. The chemical water treated sewage and fuel are dirty flow and low Reynolds respectively. The number of viscous flows does not apply to standard throttles. For the dirty flow, a non-standard throttle such as a circular orifice plate is used with a differential pressure gauge or an ultrasonic Doppler flowmeter, and the viscous flow can be respectively a volumetric, target or wedge flowmeter. The water volume of the turbine, the circulating water volume of the condenser and the regenerative steam of the regenerative unit are all flow measurement parameters of large diameter (above 400mm). Due to the difficulty in processing and large pressure loss, standard throttling devices are generally not used. According to the special characteristics of the measured medium and the measurement accuracy requirements, the characteristics of the plug-in flowmeter, the speed measuring component with the differential pressure gauge, and the ultrasonic flowmeter are respectively adopted, or the flow rate is measured by the non-loss method such as the marking method or the simulation method.

In order to ensure the service life and accuracy of the flowmeter, we must pay attention to the anti-vibration requirements of the instrument when selecting the type. Choose wet and humid instruments in hot and humid areas.

Correct selection of the instrument's specifications is also an important part of ensuring the service life and accuracy of the instrument. Special attention should be paid to the choice of static pressure and temperature resistance. The static pressure of the meter is the degree of withstand pressure. It should be slightly larger than the working pressure of the measured medium, generally 1.25 times to ensure no leakage or accident. The choice of the range of the range is mainly the choice of the upper limit of the meter scale. The selection is small, easy to overload, damage the instrument; the selection is large, which hinders the accuracy of the measurement. Generally, it is selected as 1.2 to 1.3 times of the large flow value of the zui in actual operation.

Contact instruments that are installed on production pipelines for long-term operation should also consider the energy loss caused by flow measurement components. Under normal circumstances, multiple measuring elements with large pressure loss, such as throttling elements, should not be used in the same production pipeline.

In short, there is no measurement method or flow meter that can adapt to various fluids and flow conditions. Different measurement methods and structures require different measurement operations, usage methods and conditions of use. Each type has its own unique strengths and weaknesses. Beijing Zhongrui Neng Instrument Technology Co., Ltd. specializes in producing electromagnetic flowmeters, ultrasonic flowmeters, vortex flowmeters, and turbine flowmeters. Therefore, based on a comprehensive comparison of various measurement methods and instrument characteristics, we should choose a suitable and economical and durable type that is suitable for production requirements.