基于阵列式静电传感器的密相气力输送煤粉颗粒运动特性分析

Flow characteristics of dense-phase pneumatically conveyed coal powders by electrostatic sensor arrays

首先运用有限元法系统分析了阵列式静电传感器灵敏度的分布特性.然后在密相气力输送实验装置上,利用阵列式静电传感器和电容层析成像(ECT)技术获得了不同表观气速(5.7,6.9,8.1 m/s)下的静电输出信号和管道截面的煤粉分布图像.结合ECT成像结果,利用FFT变换和近似熵方法分别得到阵列传感器输出静电信号的频谱特性和近似熵值.结果表明:随表观气速增大,输送管道内颗粒速度增大,并且稀相区颗粒径向速度波动明显;浓相区的近似熵值一直大于稀相区的近似熵值,并且随两者之差的减小,ECT成像图表明此过程煤粉分布更均匀,输送悬浮性越好.

The sensitivity of electrostatic sensor array is investigated by the finite element method.The experiments are performed in a dense-phase pneumatic conveying system,and electrostatic signals and coal powder distribution over the cross section of the pipeline under three different superficial gas velocities（5.7,6.9,8.1 m/s） are obtained,respectively,by electrostatic sensor array and electrical capacitance tomography（ECT）.Combined with ECT imaging,the frequency spectrum and approximate entropy（ApEn） value of output signals of the array are analyzed by the fast Fourier transformation（FFT） method and approximate entropy method,respectively.Results show that with the increasing superficial gas velocity,the increase of the axial particles velocity is the main dynamic change,while in dilute phase region,the particles velocity fluctuation in the radial direction also can be observed.The value of the electrostatic signal in dense-phase region is greater than that in dilute phase region.When the ApEn value difference of the electrostatic signals is smaller,the pulverized coal particles are better suspended.