Study On Miniature Atomized Particle Size Measuring Instrument

The heavy demands of particles sizing in industry and agriculture are increasing rapidly at present, so it is very important to study techniques of particles sizing and develop measuring instruments. The research and development in this field in china is close to the euramerican. There are various measuring instruments based on different measuring principle. With a good many advantages, the light scattering technique of particles size measurement gains extensive applications. The atomized particle size measuring instrument modeled WL developed by Chongqing university is successful and keep head domestically ,but its volume is large and spot operation is discommodios Thus, it is necessary to study and develop miniature measuring instrument based on the WL instrument. This thesis is founded on the problem above.When various diameter particles are irradiated by a collimated laser light beam, light scattering phenomenon takes place, and the scattering light parameter include the information of the particles size distribution. Mie scattering theory is the fundamental principle of the particle size measuring instruments and its computations are complicate. When the diameter of the particles satisfied some conditions, Mie theory is approximate to Fraunhofer diffraction theory. Therefore, if different light energies with different angle are measured, the particle size distribution can be calculated in theory. Many distribution functions are employed to approach the particle size distribution, including Rosin-Rammler function in common use ,or the algorithm of independent model should do. The light route used by measuring instrument determined its volume, according to the place between sampling area and lens, with the application background limits, the miniature atomized particles size measuring instrument takes scheme that the sampling area locate in front of the lens and the optic-electronic sensor at the back focal plane of the lens.The miniature atomized particle size measuring instrument employsseparated module ideas and is optimized. It can be divided into three parts: detector with data sampling function, PC software with data processing, displaying and storage function, they are linked with a connector. The detector design consists of design and select of optic parts of an apparatus, circuit design, sampling area control and antipollution device design. PC software include communication with detector, computing the particles size distribution, database and so on. The connector plays the role of transition of communication protocol and supply the detector with power. The design of the detector is key to realize the miniature, which is the emphases and difficulty in this thesis. Wholly, the miniature atomized particle size measuring instrument is tight and intelligent and it can be on-line dynamically measuring in a awful spot environment.