|信息来源： 华恒 | [ 2019-04-17] 点击量： 231|
What is the throttling device of orifice flowmeter and how should we define it?Xi'an Huaheng Instrument Manufacturing Co.,Ltd.
Orifice plate flowmeter is a high range ratio differential pressure flowmeter which is composed of standard orifice plate and multi-parameter differential pressure transmitter(or differential pressure transmitter,temperature transmitter and pressure transmitter).It can measure the flow of gas,steam,liquid and drainage.It is widely used in process control and measurement in petroleum,chemical industry,metallurgy,electric power,heating,water supply and other fields.
When the pressure difference between the front and back of the pipeline is large,the throttle orifice plate is often added.The principle is that when the fluid flows in the pipeline,the local resistance of the orifice plate reduces the pressure and energy loss of the fluid.This phenomenon is called throttle phenomenon in thermodynamics.This method is simpler than using control valve,but it must be selected properly.Otherwise,the liquid is prone to cavitation,which affects the safe operation of the pipeline.
The function of throttle orifice plate is to reduce the diameter of the orifice in the proper place of the pipeline.When the liquid passes through the shrinkage orifice,the flow beam will become smaller or shrink.The minimum cross-section of the beam appears downstream of the actual contraction,which is called the contraction cross-section.At the condensation section,the velocity is the largest,and the pressure at the condensation section decreases greatly with the increase of the velocity.
When the beam expands into a larger region,the velocity decreases and the pressure increases,but the downstream pressure will not completely restore to the upstream pressure,which is due to larger internal turbulence and energy consumption.