Currently, the domestic flow meter for gas measurement, gas turbine flowmeter dominates, vortex precession gas flowmeter also has a specific market. Although the use of the two occasions is more similar, users often have questions about the choice of the two.
A gas turbine flowmeter is one of the main types of flowmeter.
1.1 The principle of gas turbine flow meters
The gas entering the gas turbine flowmeter is accelerated by the guide fluid. The accelerated gas acts on the turbine’s blades through the inlet channel, and the impulse of the gas causes the turbine of the flowmeter to rotate in the flow path. Within a specific flow range, the number of turbine revolutions is proportional to the volume of gas flowing through it. Using mechanical or electromagnetic induction, we can obtain the number of processes f of the turbine and thus the flow rate Q of the gas flowing through the flowmeter.
1.2 Applications of gas turbine flowmeters
The gas turbine flowmeter is widely used to measure the flow or total volume of expensive gases such as gas. It is also commonly used to measure natural gas flow at home and abroad. The theoretical research and practical experience of gas turbine flow meters are well established, with corresponding international standards. Countries also have related national standards, and China has adopted international standards as equivalent. In Europe and the United States, the gas turbine flowmeter is the most critical gas flow measurement instrument. More than 2,600 gas turbine flowmeters are used in the Netherlands alone on natural gas pipelines.
The vortex precession gas flowmeter in the 1970s began to appear flowmeter.
2.1 The principle of the vortex precession gas flowmeter
The gas enters the gas spiral vortex flowmeter:
2.1.1 It has to pass through the spiral starter after being forced to rotate and accelerate, forming a vortex, the center of the vortex for the vortex nucleus.
2.1.2 The accelerated vortex enters the enlarged section and then decelerates sharply, and the pressure rises to produce a backflow. Under the action of the backflow, the vortex nucleus is spiraled around the axis of the flowmeter.
2.1.3 Through the sensitive element induction method to measure the vortex into the frequency f, it can be deduced from the flow Q.
2.2 Applications of the vortex precession gas flowmeter
The vortex precession gas flowmeter in foreign countries is not applied, but domestic natural gas and steam flow measurements are more valuable.
With the continuous development of the natural gas industry, the demand for gas measuring instruments is increasing. Vortex precession gas flowmeter and gas turbine flow meters are widely used in gas measurement. These two flowmeters have similar applications, with the main differences in the following sub-areas.
3.1 Medium working conditions
Gas turbine flowmeter resistance to pipeline vibration ability is good. But it has high requirements for the cleanliness of the medium. It also requires a more petite medium and no moisture gas. Such as natural gas, when we install, we need to have a 10DN straight pipe section distance before and after.
3.2 Pressure loss
Gas turbine pressure loss is slight. It is suitable for low-pressure transmission occasions. The pressure loss of the vortex precession gas flowmeter is significant. Flow measurement is ideal for a small diameter pipeline (usually below 150mm pipe diameter).
3.3 Flow range
Gas turbine range-wide is suitable for significant variations in flow rate. The spinning vortex flow range of medium is ideal for the flow of small changes in the occasion.
Theoretical research and practical experience with gas turbine flow meters are well established. It has the corresponding international standards. Currently, foreign countries use more gas turbine flowmeters and rarely use the rotary vortex. Domestic vortex precession gas flowmeter is still more widely used in measuring natural gas flow. Because of its high-cost performance and independence of fluid temperature, pressure, density, and viscosity, it is the flowmeter product of choice for some small natural gas distribution stations.
4. Feature differences
4.1 Pressure Loss
The gas turbine flowmeter pressure loss is slight. Therefore, it can be suitable for low-pressure delivery occasions of gas metering.
The vortex precession gas flowmeter pressure loss is slightly more significant. As a result, low-pressure delivery occasions of gas metering sometimes have problems.
4.2 Medium requirements
The gas turbine flowmeter on the media cleanliness requirements is high. Improper use will be damaged. The vortex precession gas flowmeter into the media cleanliness requirements are not high gas turbine flowmeters.
The gas turbine flowmeter is the highest accuracy of all flowmeters. The vortex precession gas flowmeter measurement accuracy is not as good as the former.
4.4 Good repeatability
Gas turbine flowmeter with good repeatability. It is generally preferred flowmeter—the vortex precession gas flowmeter repeatability in transaction settlement.
4.5 Frequency signal
The gas turbine flowmeter can obtain a very high-frequency signal and signal resolution. However, the vortex precession gas flowmeter frequency signal is shallow. Therefore, the larger the caliber, the lower it causes low signal resolution, which will give us the measurement error.
4.6 Scale degree wide
The gas turbine flowmeter scale is degree wide, generally 40:1 ~ 20:1. A wide-scale of measurement can be suitable for significant changes in inflow. When we transport natural gas, the flow rate changes are usually massive. Therefore, it is particularly suitable for natural gas measurement.
The vortex precession gas flowmeter scale degree is medium, generally 15:1 ~ 10:1. The scale of measurement is slightly narrower; we are in the size of gas measurement, and it is more suitable for the occasion of the flow change is not significant.
4.7 Anti-seismic function
The gas turbine flowmeter is better able to resist pipeline boom. The vortex precession gas flowmeter is susceptible to pipeline boom. When we use it, we should pay special attention to avoiding it.
In the case of standards, the International Organization for Standardization promulgated the international standard ISO9551. Global recommendations issued by the International Organization of Legal Metrology R6, R32. Our country and developed countries have the corresponding national standards and regulations, the above documents to ensure the authority of the gas turbine flowmeter in gas metering. And vortex precession gas flowmeter has not yet developed the relevant standards. Difficult to provide the flowmeter to the gas metering authority.