Valliappan, Pavithra. The effect of material and process parameters on impeller torque and power consumption in a bladed mixer. Retrieved from https://doi.org/doi:10.7282/t3-fsre-pe07
DescriptionA large number of industries including catalytic, chemical, cosmetic, food, and pharmaceutical industries frequently handle powders or granular materials in various unit operations. A cylindrical mixer mechanically agitated by an impeller blade is a common, industrially relevant geometry in numerous particle processing technologies. A bladed mixer has a capability of handling a wide variety of solid and liquid systems: free flowing and cohesive powders, pastes, or suspensions. The torque needed to move the impeller, provides insight into flow behavior of the material and can be monitored on the bench scale, pilot scale, and manufacturing scale so that it could provide useful information for scale-up and process monitoring & control. Experimental measurements of the agitation torque exerted on a particle bed and the power draw for the motor driving the impeller blades in a mixing process were conducted to investigate the impact of particle properties and blade geometry as a function of the blade rotation rate. It was found that the torque exerted on a granular bed and the power consumption were a strong function of the impeller blade configuration, the position of the blades in a deep granular bed, the fill height of the glass beads, and the size and friction coefficient of the particles. It was observed that the time-averaged torque and power consumption for different particle sizes qualitatively scaled with particle diameter. A scale-up relationship for a deep granular bed was developed: the time-averaged torque and average adjusted power consumption scaled with the square of the material fill height.