Experimental Study On Flow Patterns Of Particle Transportation In Inclined Pipe And Induced Vibration Characteristics Of Pipeline

The inclined pipe is an important part of the particle circulation loop in typical fluidization processes such as circulating fluidized bed,fluid catalytic cracking reaction-regeneration system,etc.It is mainly used to transport particles collected by the gas-solid separation system to the fluidized bed or transport particles between two fluidized beds,so as to maintain the pressure balance of the whole particle circulation system and ensure the stable operation of the entire process.The flow patterns of the particle transportation process in the inclined pipe is diverse.The change of the flow pattern is easily affected by factors such as the height of the vertical pipe connected with the inclined pipe,the mass flow rate of the particles,and the loose air volume.So,there is great theoretical significance and engineering application value to study the flow patterns of the particles in the inclined pipe under different working conditions and to investigate its effect on the induced vibration of the pipeline.In this paper,FCC catalyst particles were used as experimental materials on an inclined pipe experimental device(the inclined angle of the inclined pipe and the vertical direction is 45°and the inner diameter is 150mm).The mean particle size is67μm,and the particle density is 1561kg/m~3.Under the conditions of changing the particle mass flow rate and loose air volume,and the height of the vertical pipe section connected to the upper end of the inclined pipe,the particle transport flow patterns and its change in the inclined pipe were recorded,and the pressure at different positions of the inclined pipe was measured using a pressure sensor.The vibration displacement response of the inclined pipeline was measured with a displacement sensor.The experimental results show that with the increase of the loose air volume,the particle mass flow rate gradually increases,and the butterfly valve’s adjustment for the particle mass flow rate is in the controllable region under the action of the loose wind.With the increase of the opening degree of the butterfly valve,four kinds of flow patterns in the inclined tube appear sequentially which namely creeping flow,waving flow,stratified flow,and fluidized flow.At the same time,with the increase of the loose air volume and the decrease of the vertical riser height,the flow pattern in the tube has been significantly improved.Each flow pattern has advanced 2-3 butterfly valve openings before the loose air volume was changed.Standard deviation analysis,power spectrum analysis,and time-average processing of pressure pulsation signals can better identify the flow patterns of particle transportation and extract the characteristic values of each flow pattern.The analysis of the vibration displacement signal of the inclined tube shows that when the loose air volume and the height of the vertical riser change,it will cause the violent vibration of the pipeline.The experimental data shows that the vibration frequency of the inclined pipeline is 12.5 Hz.