Research On The Two-phase Flow Patterns And Its Impact On The Vibrations Of Inclined Pipe

Inclined pipe is one of the important components of the particle circulation system in the circulating fluidized bed.The main role of the inclined pipe is to complete the particle transport and maintain the system pressure balance.The process of particle conveying is a complicated gas-solid two-phase flow.At present,there is no fully-developed theoretical model to accurately predict gas-solid two-phase flow.The state detection and fault diagnosis of the flow process are necessary to ensure the operation of the particle circulation process,and at present,monitoring is mainly based on measured static parameters,and most of them are still based on experience.However,the pressure and the vibration displacement signals formed in the gas-solid two-phase flow in the inclined pipe contain a large amount of particle flow information,which can timely reflect the flow patterns and the flow state of the particles.The sensitivity of these signals is much higher than that of the static parameters,which can be used for the detection and analysis of gas-solid two-phase flow patterns in the inclined pipes.Therefore,in this paper,the pressure signal and inclined pipe vibration displacement signal in the process of granule unloading are analyzed to accurately identify the different flow patterns of particles in the inclined pipe and the mechanism of flow induced vibration of inclinedpipe was investigated.The conclusions obtained in this work are described as follows.In an experimental device with an inclination angle of 45° and a diameter of ?150 mm,the butterfly valve adopts two installation methods to adjust the downward conveying process of catalyst particles.In the first case,the stem of the butterfly valve is above the inclined pipe.In the second case,the stem of the butterfly valve is on the side of the inclined tube.The experimental results show that the particle flow rate changes nonlinearly with the butterfly valve opening,and there are two non-controllable zones and one controllable zone for the regulation of the particle flow rate by the butterfly valve.The flow pattern in the inclined pipe is changed in sequence.When the valve stem is located above the inclined pipe,the creeping flow,fluctuating flow,stratified flow,and the fluidized flow are respectively shown with the opening degree.When the valve stem is located on the side of the inclined pipe,the flow patterns are creeping flow,fluctuating flow,dense-phase fluidized flow,and dilute-phase fluidized flow.Standard deviation analysis,power spectrum analysis,wavelet analysis are applied to the pressure signal to identify the particle flow patterns.The analysis of the vibration displacement signal indicates that when the flow state in the inclined pipe and the installation method of the butterfly valve are different,and the vibration severity of the inclined pipe will be different.