The Equipment Design For Preparing Superfine Particles Using Supercritical Fluid (SCF) Technology And The Simulation For The Precipitator's Flowing Field

In this paper the technology of preparing superfine particles using supercritical fluid (SCF) technology has been introduced first, the summarization of SAS and RESS equipment has also been given. By improving and optimizing the equipment design, the SCF technology could be used more widely in industry.Two new flowcharts, which are the continuous versatile process and the experimental versatile process, were designed. The operating specification and the specialties of the continuous versatile process have also been determined. The specific operating condition and the capability of the equipment were introduced for the experimental versatile process. The structures for the main parts, such as the dissolving vessel, the precipitator and the nozzle, were designed in this paper, and their dimension and installation specification were given, the specification of their capability was presented as well.The precipitator is the most important part for the technology, which is the location of preparing particles. The SCF and the solution get mixed in this vessel, and their mixing effect has a great influence to the final size and the distribution of the particles. We selected the model of two-passages with blend-outside mode precipitator as a simulating example. Based on the numerical analysis of Computational Fluid Dynamics (CFD), the geometry model for the preparing zone was established, and the mesh file was made by the Gambit software. Then this file was induced into the Fluent software and calculated. Based on the data that was given by this software, the infection of the position of the thermometer cannula and the figure of the precipitator to the mixing effect in the particle's preparing zone were analyzed. It turned out that when the thermometer cannula was located near the spraying zone of nozzle, it had a greater influence to the precipitator's flowing field, in the mean while, the existence of the right-angle zone in the combining region of precipitator and nozzle, the turbulence intensity became more fierce. According to the result, the structure of the precipitator and the position of the thermometer cannula were modified, and the mixing effect for the SCF and the solution was improved. It would be the guidelines to improve the design and the manufacture of the precipitator.This work could have an important meaning to developping the technology in industrial appilication.