Study On Coaxial Two Impinging-stream Concentrator

The impinging stream is a technology which has been proved intensifying the transport processes. It has been successfully applied to many processes in chemical engineering, such as drying of solid particles, making super fine powders and intensifying the mixing in chemical reactors. In this work, it is further developed as a new concentrator. A systematic study on the concentrator is carried out experimentally and theoretically. The results will be useful in developing a new concentrator.Sugar cane solution is used as a trial solution in the experiment. The experimental results show that firstly, the evaporative capacity of the impinging stream concentrator increases with increased inlet air temperature, decreased with the ratio of inlet sugar cane solution flow rate to inlet gas flow rate; secondly, the pressure drop of the impinging stream concentrator increases with increased inlet air flow rate; thirdly, the impinging stream concentrator has a high volumetric evaporative coefficient, and it increases with increased inlet ail flow rate and increased inlet air temperature. Two lengths of the accelerating pipe are introduced to study the performance of the impinging stream concentrator. The results show that it is better to apply a short accelerating pipe to the concentrator. Additionally, a dimensionless equation for the concentration of the solution is obtained by regressing the experimental data, which can predict concentration of the solution with -22.4% to 25.8% relative errors.A model is established based on theoretical analysis. In virtue of the mathematical model, the trace of droplet, the velocities of droplets and gas, the temperature of air and droplets, the residence time of the droplets, the evaporatedrate of droplets, the concentration of droplets, the diameter of droplets, the penetrating depth of droplets and the effects of the experimental parameters (inlet gas temperature, inlet gas flow rate, inlet solution flow rate) on evaporated rate are numerically simulated. Moreover, the simulative results are analyzed and discussed. The model is proved by comparison between expenmental data and predicted results of ISC's evaporative capacity. The model can be used to aid the design of impinging stream concentrator in some degree.