Research On Dry Ice Blasting Technology

As a new clean technology, dry ice blasting is characterized in high efficient, wide application and no pollution, which had been used in the field of mould, power electronics, petrochemical industry, automobile and so on. However,there were some problems about dry ice blasting technology that were used in modern industries, such as the large equipment, low utilization rate of dry ice and lack of proper theoretical guidance, which limited the development and application extension of dry ice blasting. Thesis researched the distributed characteristics of nozzle flow field with numerical simulation and experiments, optimized the process parameters of dry ice blasting, and studied the characteristics of dry ice blasting technology.A device of extruding dry ice particles against the problems that dry ice particles were oversize produced by industries and narrow application was designed, which could produce cylindrical particles,1mm in diameter, and0.5～10mm long. The device of extruding dry ice particles can clean the precision components and improved utilization rate of dry ice particles. An experiment device of dry ice blasting by the mode of double throat was designed to solve the problem that dry ice particles usually happened obstruction in the process of dry ice blasting working, which efficiency was improved as well.Inner flow field of cylindrical nozzle and venturi nozzle and the flow field of jet flow sprayed by nozzles were simulated with software Fluent, which obtained the distribution results of pressure and velocity of fluid. The results show that the velocity of venturi nozzle airflow is more faster than cylindrical nozzle airflow’s near the exit of nozzle(<15mm). With the distance from nozzle exit increasing, the velocity of venturi nozzle airflow weaken more earlier than cylindrical nozzle airflow’s, the mean velocity of cylindrical nozzle airflow is faster than venturi nozzle airflow’s. The motion path of particles sprayed by nozzles was simulated by the Eulerian Lagrangian method, the results show that the particles sprayed by cylindrical nozzles distribute around the axis of nozzle, while the motion path of particles sprayed by venturi nozzles is divergent, and the particles are distributed equably in the zone. An experiment of cleaning the paint plate adopting two kinds of nozzles was conducted, the results verified simulation analysis.In order to optimize the process parameters of dry ice blasting, an experience of dry ice blasting to clean steel plate with paint was conducted. Obtained the best parameters by observed the impact of different parameters on cleaning effect, which were dry ice mass flow. spray angle, work distance and feed speed. An experience of dry ice blasting cleaned6kings of contaminants and aluminum plate with paint was conducted, the results show that the dry ice blasting technology is suitable to clean organic fouling or overlaid fouling, besides, dry ice blasting technology has a weak destroy on the surface of substrates, and is suitable to clean the surface that has high surface quality requirement or is fragile.