How to improve the measurement accuracy of ultrasonic flowmeter under elbow

2022-11-04

How to improve the measurement accuracy of ultrasonic flowmeter under elbow

With the development of science and technology, more and more new instruments are applied to the measurement of oil fields, such as ultrasonic flowmeters, mass flowmeters, etc. Ultrasonic flowmeter has unique advantages when it is used for fluid measurement. It is a non-contact instrument, does not change the fluid form, is easy to install, can measure the flow of strong corrosive media and non-conductive media, and the measurement process is not affected by temperature and pressure. , density and viscosity and other physical parameters. But the ultrasonic flowmeter also has some shortcomings, mainly due to its poor anti-interference ability, air bubbles, scaling, etc., which will affect its measurement accuracy, and strict requirements for straight pipe sections during installation. Otherwise, the discreteness is poor, and the measurement accuracy is low. In the actual field application in the oil field, there will inevitably be some non-standard installation conditions in the application places of some ultrasonic flowmeters, such as the insufficient length of the straight pipe section and the existence of elbows in the upstream. In order to improve the measurement accuracy of ultrasonic flowmeter under non-standard conditions, this paper selects the time difference method portable ultrasonic flowmeter, which is widely used in oilfields, as the research object. The accuracy changes, and a corresponding mathematical model is established to correct the measurement error of the ultrasonic flowmeter, thereby improving the measurement accuracy of the ultrasonic flowmeter in the presence of elbows.

The simulation study of the existence of elbows upstream of the ultrasonic flowmeter shows that in the case of elbows, at (2~10)D, the maximum measurement error of the ultrasonic flowmeter can reach 10%, and the error increases with the increase of the flow rate. , in the (10~15) D stage, the ultrasonic flowmeter error gradually becomes smaller, and turns from positive error to negative error. After 15D, the measurement error of the ultrasonic flowmeter gradually decreases and approaches 0; on the basis of the simulation research , The error curve correction model was fitted. After field test verification, the established correction model has high accuracy. After correction, the measurement error of the ultrasonic flowmeter can be controlled within ±1.0%, which greatly improves the ultrasonic flowmeter. Measurement accuracy under elbows.

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