Study On Phase Holdup Measurement Method For Bubble Bed Based On Capacitivelv Coupled Electrical Resistance Tomography System

Electrical resistance tomography has already become the hotspot in the research of multi-phase flow due to the advantages of simple structure,low cost and good robustness,etc.Capacitively coupled electrical resistance tomography(CCERT)is a new tomography technique with broad application prospects that combining capacitively coupled contactless conductivity detection technique and electrical resistance tomography to implement contactless measurement,which can avoid a series of problems such as electrochemical erosion.Based on the previous work,a capacitively coupled electrical resistance tomography system prototype is developed and the corresponding model of gas-liquid tow-phase holdup measurement is established by the static experiments.Meanwhile,the dynamic phase holdup measurement experiments and real-time image reconstruction experiments are carried out in the gas-liquid two-phase bubble bed,which implement the monitoring of the two-phase flow in the bubble bed.On this basis,the gas holdup measurement model based on the acoustic emission technology is established and combined with the phase holdup measurement model of CCERT to measure the holdup of every phase in gas-liquid-solid three-phase flow.The main works and innovation points are listed as follows:(1)A prototype of CCERT system is developed to realize data collection and tomography.Then,the prototype is applied to the gas-liquid bubble bed for dynamic tomography.(2)The phase holdup measurement model based on CCERT is established by the static experiments and the dynamic phase holdup measurement is implemented with the developed models.The principal component regression method and partial least squares regression method are introduced for signal processing with the data obtained by the CCERT system.Then,the two models of phase holdup measurement are established and compared.The dynamic phase holdup measurement experiments are carried out in the bubble bed by using the phase holdup measurement model established.According to the results of experiment,the feasibility of the phase holdup measurement models based on CCERT system is verified further.(3)A contactless phase holdup measurement method of the gas-liquid-solid three-phase flow is proposed and the dynamic experiments are carried out in three-phase bubble bed.Firstly,the acoustic signals collected by acoustic emission system are analyzed and processed to verify the feasibility of measuring phase holdup by acoustic emission technology.Then the phase holdup measurement model is established by partial least squares regression.Finally,the holdup of every phase in the gas-liquid-solid three-phase flow is measured in the dynamic experiments,combining the phase holdup measurement models based on CCERT and acoustic emission.According to the results of experiments,the feasibility and effectiveness of the proposed contactless phase holdup measurement method are verified.