Study On The Measurement Of Particle Size Distribution In Gas-solid Two-phase Flow By Laser Particle Size Analyzer

In scientific research、industrial and agricultural production,many solid materials and products are in the form of particles.Particle size distribution plays an important role in the quality and performance of these products.The laser particle size meter uses the scattering(diffraction)phenomenon to measure the size of the particles.It has many advantages,such as wide range of particle size,wide application range,good reproducibility,fast measuring speed.It has been widely used in the fields of metallurgy,food,pharmacy,building materials and so on.In this paper,the principle of the equivalent sphere used to characterize the surface properties of particles is studied in this paper.The reasons for the error caused by the different equivalent methods are analyzed.Then,the principle,the scope of application and the advantages and disadvantages of the traditional measurement method of particle size and the method of laser measurement are compared and analyzed.The reasons for the difference in the measurement results are found out for the same particle,because the measurement method is not.On the premise of laser measurement,the principle of wet dispersion and different dispersing methods for the particles are analyzed.(medium regulation,drug control,mechanical mixing,ultrasonic dispersion);Dry dispersion principle and different dispersing methods(dry dispersion,mechanical dispersion,surface modification,classical dispersion).The initial application range of Malvin Spraytec laser spray particle size meter is to measure the particle size of spray and to measure particle size in the state of solid liquid two phase flow.In order to expand the application of the instrument to the measurement of the distribution characteristics of solid particles in the state of gas-solid two phase flow,According to the particles with different particle sizes(ultrafine particles,general particles and large particles),the dispersed fluidized devices with different structures are designed and made.According to the difference of the dispersing process,the calculation problem of the minimum dispersed flow rate is explored in terms of the force balance model and the kinetic energy balance model.For large particles,through different drag model on Calculation of minimum fluidization velocity dispersion.After dispersing the sample particles in a dispersed fluidized bed,a uniform gas-solid two-phase flow is obtained.Malvin Spraytec Laser Particle Sizer is used to measure the characteristics of sample particles in gas-solid two-phase flow,and the experimental results of particle distribution characteristics under different measurement parameters are obtained.The results of the actual distribution of the sample particles were obtained by electron microscope imaging of the same sample.The two experimental results are compared,and the factors that affect the measurement error are analyzed.The setting of measurement parameters suitable for different kinds of particles is found,and finally the accuracy of measurement is improved.