Study Of Spatial Filtering Of Particle Parameters Measurement Based On Linear Electrostatic Sensor Matrix

Gas-solid two-phase flow phenomenon is one of the existing forms of multi-phase flow,which is widely existed in natural and industrial production,such as atmosph eric dust flow and wind-sand phenomenon in nature,pulverized coal transportation in thermal power plants and blast furnace dusting system in steelworks.In order to use and operate energy efficiently and safely,it is necessary to accurately and real-time measure the particle fl ow velocity and concentration of the pipeline.During the transport of solid particles,the conveyed solid particles are charged due to the collision and friction between particle and particle,particle and pipe,which forms electrostatic noise in the conveying pipe.The electrostatic noise contains a large amount of information such as particle velocity and concentration,and the electrostatic sensor can non-invasively capture the electrostatic noise carried by the moving particles,and can obtain various information of the flow state of the particle through the process.In this paper,Linear electrostatic sensor matrix structure is designed,with the idea of spatial filtering to process the output signal,the particle velocity and concentration in the pipeline can be calculated.The sensor structure can effectively overcome the problem that the sensor of the existing structure affects the peak frequency due to the uneven distribution of the sensitive field,thereby reducing the measurement error of the particle parameter.In this paper,the finite element simulation software COMSOL Multiphysics is used to establish a model of the linear electrostatic sensor matrix.Then the spatial sensitivity distribution of the electrostatic sensor is analyzed by simulation.The axial static sensitivity and dynamic sensitivity distribution of the sensor are obtained.Based on this,a dimensionless model is established by using the principle of similarity.Based on the analysis of the spatial dynamic sensitivity distribution of linear electrostatic sensors matrix,the influence of the electrode structure parameters on the dynamic sensitivity distribution is studied in detail,and the structural parameters of the sensor are optimized.For the dynamic sensitivity distribution of linear electrostatic sensors matrix,the spatial filtering characteristics are analyzed.Firstly,the relationship between the particles and the peak frequency at different radial positions and particle sizes is analyzed.Then,the peak frequency values of the output signals at different velocities are obtained,and the linear ratio between velocity and peak frequency is obtained by fitting.Meanwhile,in order to reasonably determine the axial number of the sensor electrodes,the frequency bandwidth under different axial electrode numbers was studied,and general recommendations were made.Finally,the spatial filtering characteristics of linear electrostatic sensors matrix,the velocity and concentration of solid particles,and other related experiments were carried out on the experimental platform of gravity transport particle flow.It is verified by experiments that the linear electrostatic sensor matrix solves the problem that the traditional electrostatic sensor affects the peak frequency of the spectrum due to the uneven distribution of sensitivity;Under the given sensor structural parameters,the drop height is 0.27m to 1.15m,and the relative error range of rubber particle velocity measurement is from 1.24%to 7.53%.In the velocity range of 2.34 m/s?4.75 m/s,the standard deviation of the measurement system for rubber particle repeatability is better than 10%.The particle concentration ranged from 1.05kg/m3 to 3.21kg/m3,and the range of particle drop height from 0.28m to 1.35m,the correlation coefficient between the particle concentration and the curve area of the power spectral density function reached 0.981?0.995.The standard deviation of the experimental measurements is better than 16%.