Industry new

Turbine flowmeter with high measurement accuracy

Turbine flowmeters are commonly used in petrochemical and urban gas industries due to their high measurement accuracy, inconvenient operation and wide measurement scale. Turbine flowmeters can be used both as a process control instrument and as a trade settlement meter. Therefore, in practice, there will inevitably be problems such as the nature of the measured medium, caliber choice, device conditions, training and calibration. In order to ensure the normal operation of the turbine flowmeter, the following issues should be paid attention to in the course of its application:
1. Turbine flowmeter has a strict request for the measured medium
a. Turbine flowmeters are only used to measure low viscosity single phase fluids
b. The medium fluid metered by the turbine flow meter should be in turbulent condition
c. Most of the current turbine flowmeter bearings are spherical bearings, so there is a high demand for the cleanliness of the measured medium. If the medium contains particulate impurities, the bearing will wear rapidly. If it contains fibrous impurities, it will entangle on the turbine blades and affect the normal rotation of the turbine. In practice, an effective filter can be installed at the front end of the turbine flow meter.
2. The choice of turbine flowmeter should pay attention to the problem
When selecting the diameter of the turbine flowmeter, the flow rate of the medium should be between 15% and 70% of the flowmeter measurement scale. When the measured medium flow rate is below 15% of the selected flowmeter measurement scale, the flow velocity of the medium fluid in the pipeline is laminar in a laminar flow condition, and the measurement of the flowmeter linearly deteriorates, and it is difficult to reach the requested measurement accuracy. When the medium operating condition flow is greater than 70% of the measured flowmeter size, the turbine speed will become very large, and the wear of the decelerating bearing and the bracket will affect the service life of the turbine flowmeter.
3. The problem that the turbine flowmeter should pay attention to in the device
a. Dispersion of media fluid flow velocity and vortex flow are important factors affecting the measurement accuracy of the turbine flowmeter. To eliminate the uneven flow velocity and the vortex flow, it is necessary to have a long straight pipe section at the front end of the turbine flowmeter. Individually requested to have a straight pipe section of 15D or more under the turbine flowmeter, and a straight pipe section with a 4D capacity to ensure the accuracy of the measurement. If the request cannot be reached by the device site, a pipe speed rectifier can be installed on the lower straight pipe section.
b. Turbine flowmeter device points must not have severe mechanical shock and strong electromagnetic disturbance. There shall be no welding slag and flange sealing gasket protruding into the pipeline in the welding and the device. The master valve of the flowmeter must be set to a fully open ball valve or gate valve to avoid affecting the flow state of the measured medium.
c. The turbine flow meter can be a degree, tilt, and vertical device in the device method, and the flow characteristic curve is changed depending on the device method. In order to obtain high-precision measurements, it is necessary to adopt a degree device. If it is certain to take a vertical device, the vertical device method is used to recalibrate the turbine flow meter, and the meter factor is newly set.
4. Training and verification should pay attention to the problem
A. The failure of the turbine flowmeter is mostly that the turbine bearing wears and the impeller is stuck. The faulty user can just handle the change of the bearing or remove the debris on the impeller. However, the turbine flowmeter is a carefully disassembled fine instrument. If the fitting is changed or removed from the new one, the meter factor will be changed. Therefore, in order to ensure the accuracy of the measurement, the meter factor should be recalibrated and changed after the replacement of the fitting or the new disassembly.
B. The turbine flow meter will change with the time of operation or the component of the meter will change, so the turbine flow meter must be verified. Calibration should focus on two issues:
a. Verify that the fluid medium used must be the same medium or a medium of similar viscosity as the measured medium;
b. If the turbine flowmeter is used to request a center with high measurement accuracy, the calibration should be performed as a whole along with the straight pipe section of the flowmeter to remove the additional error of the straight pipe section before and after the turbine flowmeter.

PREVIOUS：Introduction to the use of gas flowmeters in NEXT：Introduction to the zero point stability of e