Advantages and disadvantages of gas turbine flowmeter

Project Overview

Gas turbine flow meters are mainly used to measure the flow of air, nitrogen, oxygen, hydrogen, biogas, natural gas, steam and other medium fluids in industrial pipelines. When measuring the volume flow under working conditions, it is almost not affected by the fluid density, pressure, temperature, The influence of parameters such as viscosity. There are no moving mechanical parts, so it has high reliability and low maintenance. Instrument parameters can be stable for a long time. The gas vortex flowmeter uses a piezoelectric stress sensor, which is highly reliable and can work in the operating temperature range of -20°C to +250°C. It has analog standard signals and digital pulse signal output, which is easy to use with digital systems such as computers. It is a relatively advanced and ideal flow meter.

The pulse frequency signal output by the gas vortex flowmeter is not affected by changes in fluid physical properties and components, that is, the instrument coefficient is only related to the shape and size of the vortex generator and the pipe within a certain Reynolds number range. However, as a flow meter, it is necessary to detect mass flow in material balance and energy measurement. At this time, the output signal of the flow meter should monitor the volume flow and fluid density at the same time. The physical properties and components of the fluid still have a direct impact on flow measurement. The gas vortex flowmeter is a new type of flowmeter that measures fluid flow in closed pipes based on the Karman vortex principle. Because of its good medium adaptability, it can directly measure the working condition volume flow of steam, air, gas, water, and liquid without temperature and pressure compensation. It is equipped with temperature and pressure sensors to measure standard condition volume flow and mass flow. It is an ideal throttling device. An ideal replacement for type flow meters.

In order to improve the high temperature resistance and vibration resistance of gas, the gas vortex flowmeter has a unique structure and material selection that allows the sensor to be used in harsh working conditions with high temperature (350℃) and strong vibration (≤1g). Use under circumstances. In practical applications, large flow rates are often far lower than the upper limit of the meter. As the load changes, small flow rates tend to be lower than the lower limit of the meter. The meter is not working in its optimal working range. In order to solve this problem Problem, usually the diameter of the measuring point is reduced to increase the flow rate at the measuring point, and an instrument with a smaller diameter is selected to facilitate the measurement of the instrument. However, this diameter reduction method must have a straight pipe section with a length of more than 15D between the reducing pipe and the instrument. Rectification makes processing and installation inconvenient.

For the convenience of use, the battery-powered local display gas vortex flowmeter adopts high-tech micro-power consumption. It can run uninterrupted for more than one year using lithium battery, saving cables and Displays the purchase and installation costs of the instrument, and can display instantaneous flow, cumulative flow, etc. on the spot. The temperature-compensated integrated vortex flowmeter also has a temperature sensor, which can directly measure the temperature of saturated steam and calculate the pressure, thereby displaying the mass flow rate of saturated steam. The integrated temperature and pressure compensation type is equipped with temperature and pressure sensors. It is used for gas flow measurement and can directly measure the temperature and pressure of the gas medium, thereby displaying the standard volume flow rate of the gas.

Application fields:

Suitable for clean gases with medium and low flow rates such as natural gas, nitrogen, and compressed air; not suitable for liquids or high-temperature steam and moisture.

1. Main advantages of gas turbine flowmeter

1. High accuracy: the full range is generally 1%-2.0%, and the high-precision type is 0.5%-1.0%; it is a type of high accuracy.

2. Good repeatability: generally up to 0.05% ~ 0.2%. Due to its good repeatability, high accuracy can be achieved through frequent calibration or online calibration, so it is used in trade settlement. One of the preferred flowmeters.

3. Wide range: medium and large diameters can generally reach more than 20:1, small diameters are 10:1, and the initial flow rate is also low.

4. The pressure loss is small: generally 0.1~2.5kPa under normal pressure.

5. Compact structure, light volume, easy to install and use, and large circulation capacity.

6. A variety of display modes can be used. It can only be equipped with a mechanical counter or only an ordinary flow totalizer. It can also add a temperature and pressure compensator to the mechanical counter, or it can only be equipped with a temperature and pressure compensator. , and can be powered by lithium batteries for a long time and is easy to use.

7. Since pulse frequency signal output is generally used, it is suitable for total measurement and connection with computers, has no zero point drift, and has strong anti-interference ability. At the same time, if high-frequency signal output is used, a very high frequency signal (3-4kHz) can be obtained with strong signal resolution.

2. Main disadvantages of gas turbine flow meters

1. To maintain calibration characteristics for a long time, regular calibration is required. Suspended solids or corrosive components contained in the medium will cause problems such as bearing wear and jamming, which will change its accuracy and limit its scope of application. Although the situation has improved after using wear-resistant carbide shafts and bearings, this problem Still exists. Therefore, it must be calibrated regularly. For trade storage and transportation and high-precision measurement requirements, it is best to be equipped with on-site calibration equipment.

2. Regularly add oil to ensure sufficient lubrication of the bearings to ensure measurement accuracy and extend service life.

3. The physical properties of the medium (such as density, viscosity, etc.) have a great influence on the characteristics of the turbine flowmeter. The gas flow meter is easily affected by density and is closely related to temperature and pressure, so it needs to be corrected for temperature and pressure.

3. Gas turbine flowmeters are not suitable for situations

1. Gas turbine flowmeters are greatly affected by the flow field distribution. Therefore, for flowmeters without rectifiers at the inlet, the sensor should be calibrated as required. Straight pipe sections are set up on the upstream and downstream sides of the flow meter. For flowmeters designed with a rectifier at the inlet, the length of the straight pipe section should also be set according to the requirements of the instructions for use.

2. It is not suitable for use in situations with strong pulsating flow, nor is it suitable for the measurement of mixed-phase flow.

3. The cleanliness requirements of the measured medium are relatively high, and filters need to be installed as required, but this also brings about an increase in pressure loss.

4. The flow characteristics of small-diameter turbine flowmeters are seriously affected by physical properties, so it is difficult to improve the performance of small-diameter turbine flowmeters. For example, the small diameter is DN25, but its range is only 10:1 and its high accuracy is only ±1.0%.

5. It is not allowed to be used in situations where quick switches exist.