Research On On-line Measurement Of Energy Particle Fineness With Ultrasonic Method

The technology of fineness measurement have been widely used in energy,mining,chemical and other fields.For the energy particle,such as tapioca powder,rice husk,pulverized coal and so on,the accurate measurement of fineness is crucial adjective in the optimize of the combustion condition and reducing the pollutant emission.In this article,with the engineering application background of the finesse measurement of pulverized coal in coal-fired power plant,the method of finesse measurement have been explored.The ultrasonic wave has the advantages of non-connect,clean,fast response.And there is a favorable prospect in the finesse measurement of pulverized coal which is the representative of energy particle.In this research,focusing on the project of energy pparticle finesse measurement,the following work has been carried out.(1)In order to obtain the ultrasonic attenuation coefficient in different particle size,ultrasonic frequency and solid concentration,some parameters are obtained by the methods of consulting literature and experiment.With the exist theoretical model,the numerical simulation of sound attenuation in gas-solid media are made.And the sound attenuation with different frequency of ultrasonic,different particle size,different volume concentration has been gotten ·(2)In order to measure the attenuation coefficient of gas solid two phase flow,the experiment platform for finesse measurement with ultrasonic wave has been built.,The pulverized coal is replaced by glass beed to do sound attenuation experiment.The sound attenuation with different particle size,different ultrasonic frequency,and different different volume concentration has gotten,and the experimental data has been compared with the theoretical data.(3)According to the experimental results,the existing theoretical models are modified.In order to make the mathematical model of ultrasonic attenuation is close to the real condition,the equivalent volume diameter is replaced by equivalent surface area diameter.And the influence factor of correction factor and specific surface area is discussed.In the 50～100μm range of particle size,the attenuation variation of 40KHz and 100KHz ultrasonic is clearly.And the inversion curves show highly coincidence with the experimental data.