Development And Study Of A Novel Mixer/Crystallizer

Due to the importance of mixing to crystallization and reaction processes, a novel mixing device/crystallizer has been developed using a membrane vibration element, which aims to overcome the shortcomings of traditional agitation mixing from studying new mixing technology. Nowadays, most of reactors or crystallizers in chemical industry employ agitation system for mixing. In this traditional mixing method, fluid is interacted with impellers and energy is input into system to form a certain flow pattern and then mixed. Such mixing method may give some static zones and result in ununiformity of the solid phase distribution; another disadvantage is that the high shear stress and direct collision brought in by impellers are unfavorable to second-nucleation because of the collision between impellers and crystals by reason of too strong shear stress. Based on the concept of modern hydrodynamics, a novel mixing device/crystallizer has been proposed and developed, which can achieve lowest shear stress and the maximum uniformity for solid suspension without any internal agitator. After designing and fabricating the mixer, we studied the flow pattern by a direct visual technique and measured mixing times of fluids at different middle-high viscosity using a decolorized method. By changing the vibration frequencies we found the optimal operation conditions in terms of mixing time. At the same time, in order to simulate crystallization process we also studied behaviours of solid suspension in the mixer by putting various density particles. This novel mixing device can be widely used in many processes with great commercial and market potential.