Experimental Study Of Pipeline Liquid Loading Vibration Monitoring Technology

In this paper, many vibration tests were carried out on the large-scale multiphase flow experiment loop road of College of Storage & Transportation and Architectural Engineering in China University of Petroleum (East China),taking air and water as the medium.The study was conducted in condition of single-phase gas and gas-liquid two-phase flow individually, which includes tests on the horizontal pipeline and hilly terrain pipeline.The main purpose of the experiment is to observe the vibration signal changes of the gas-liquid two-phase flow pipeline.Accumulated liquid volume changes should be monitored in the pipeline.when the fluid volume is low, the gas-liquid two-phase flow patterns in the pipeline are mainly stratified wavy flow and slug flow induced by hilly terrain;When the liquid volume is high,the gas-liquid two-phase flow patterns are mainly stratified smooth flow, plug flow and slug flow.From upstream to downstream,there were 12 measuring points on the horizontal pipeline and 9 measuring points on the hilly terrain pipeline.Vibration analysis was preceded by a detailed summary of the pipe vibration for various reasons,in order to analysis the collected vibration data better.First,vibration velocity spectrum analysis and vibration energy analysis for each measuring point on the horizontal pipeline were carried out,using the vibration spectrums and vibration data.It was found that under the stratified wavy flow, the exciting force of two-phase flow is very small,the main reason of the pipeline's vibration is air pressure fluctuation of the compressor pipeline.In the slug flow condition, the main reason is two-phase flow induced vibration;Besides,according to the flow patterns,combined with gas-liquid two-phase flow parameters such as pressure and pressure drop,a detailed analysis of the hilly terrain pipeline vibration mechanism was conducted.When the flow pattern is stratified flow and plug flow, the main reason of the pipeline's vibration is the effect of the fluid-solid coupling.When it is slug flow,the impact of gas-liquid pulse is the main cause of horizontal vibration on the hilly pipeline.In addition,according to the vibration velocity energy spectral density,vibration intensity trend including both of the horizontal pipeline and the hilly terrain pipeline on horizontal and vertical individually,vibration intensity trend on the hilly terrain pipeline in condition of the elbow and vibration intensity trend on the hilly terrain pipeline when the tilt angle changes were summed up when the gas or liquid flow rate changes;Finally,a detailed comparison was concluded about the vibration intensity of the hydrodynamic slug flow with the terrain-induced slug flow.Through the experiment,it can be found that on the horizontal direction and vertical direction of hilly pipeline,vibration velocity energy spectrum density increases as the rise of the liquid flow rate,and vibration velocity energy spectrum density of the water power slug flow decreases as the rise of angle of inclination.Vibration velocity energy spectrum density of slug flow induced by hilly terrain increases as the rise of tile on the downward inclined pipeline.Every measuring point's vibration velocity energy spectrum density of slug flow induced by hilly terrain is greater than that of water power slug flow on the downward inclined pipeline.Finally, numerical simulation of gas-solid coupling, liquid-solid coupling and gas-liquid two-phase fluid-solid coupling were carried out. The results also show the impact of two-phase flow pulse on the pipeline mainly occurred in the horizontal direction.