"ZOOM" SEMINAR
School of Mechanical Engineering Seminar
Wednesday, December 9, 2020 at 14:00
Characterization of particles for conveying and handling using a Rheometer
by
Yeshayahu Levin
MSc. student Prof. Amos Ullmann and Prof. Haim Kalman
Hydraulic and pneumatic conveying systems of powder and granular solids are based on drifting particles by gas or liquid flow and thus transporting them from place to place. In designing such conveying systems, the flow velocity must be determined so that the system is as efficient as possible. The flow velocity at which particles immersed at the bottom of the tube rise and drift with the flow is called the Pick-up velocity or Critical velocity. In designing the flow velocity in the system, the Pick-up velocity must be taken into account. Additionally, classifying the particles in the mixture as 'settling' or 'non-settling' may simplify the calculations and the design of conveying systems.
The research deals with measuring powders and suspensions viscosity, Pick-up velocity, and classifying particles in mixtures as 'settling' or 'non-settling' using a rheometer, a device that usually used for measuring fluid viscosities.
The measurements are based on analyzing the properties of suspensions. In particular, on the fact that the suspension viscosity increases as the particle concentration increases. Thus, the velocity at which particles from the sediment layer rise into the flow can be identified by following the changes in the suspension viscosity while increasing the impeller rotation speed. Analyzing the viscosity of the suspension when the speed decreases gradually, allows characterizing the particles as 'settling' or 'non-settling'.
The measurements conducted using the rheometer were compared to the results and correlations presented in previous studies. We show that measuring the Pick-up velocity with a rheometer, which is simpler and faster than the common methods in the field, can achieve the same results. Additionally, we show that by using a rheometer it's possible to expand the existing knowledge on classifying particles in slurries as 'settling' or 'non-settling'.
https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09 The meeting will be recorded and made available on the School’s site.
