Vortex flowmeters are mainly used for the flow measurement of industrial pipeline fluids. Vortex flowmeters are widely used in petroleum, chemical, metallurgical, thermal, textile, papermaking and other industries for superheated steam, saturated steam, compressed air and general gas, water and Liquid metering and control. The volume of saturated steam and superheated steam is greatly affected by temperature and pressure.
One-time compensation realization method
First determine the working parameters of the steam—temperature and pressure. The vortex flowmeter determines the density of the steam in the working state according to the working parameters, and calculates this density as the density of the steam in the future flow measurement process. The actual change of steam is no longer compensated or corrected during work. This is the so-called one-time calculation compensation method.
If during operation, the working parameters of the steam are consistent with the set values during design, the accuracy of the steam flow measurement can be guaranteed. If the parameters under actual working conditions deviate, or even deviate greatly, the deviation of the measurement results may be large.
The one-time compensation method, the measurement method adopted in the early stage of the development of automatic detection technology, has a large error in the measurement result and can be used as a rough measurement. This design method is still in use in the current widely popular flow throttling device design manual.
Online density compensation realization method
With the widespread application of microelectronics technology in meters. The calculation function, compensation correction function, accumulation function, historical data storage function, digital filtering function, output function, digital communication function, etc. of the vortex flowmeter can all be easily realized. Online density compensation has become an indispensable basic function of steam metering instruments and is widely used. The following introduces the classification of steam density compensation:
1. On-line density compensation of saturated steam
The vortex flowmeter can realize integrated temperature and pressure compensation, and there is a strict one-to-one correspondence between the temperature and pressure of saturated steam. The density of saturated steam can be a single function of its temperature or its pressure. According to the temperature value or pressure value of the saturated steam, the real-time density value can be obtained by the look-up table method or formula calculation method (IFC1967 or IAPW-1997).
In flow measurement, vortex flowmeter can choose temperature compensation or pressure compensation type flowmeter to realize. To select a flow meter with temperature compensation function. Turn on the temperature sensor of the flowmeter to detect the measured steam temperature in real time to obtain the corresponding density value.
2. On-line density compensation of superheated steam
Superheated steam is a special quality steam obtained by reheating saturated steam. It breaks the strict one-to-one correspondence between temperature and pressure inherent in saturated steam. The vortex flowmeter can treat the superheated steam as a single medium in the flow measurement process. The density of superheated steam is a comprehensive function of its temperature and pressure. When ordering a vortex flowmeter, select the temperature and pressure compensation type. In actual use, the temperature and pressure sensors are turned on at the same time to measure the steam temperature and pressure value in real time. The density value can be accurately calculated according to the superheated steam density table or density calculation formula.