(147c) Learning Separations

I will describe a different way of learning separations. Separation of a mixture involves movement of a specific species to a specific region in the separation system which gets enriched in that species. This is caused by species-specific forces driving a species relative to other species. The same argument is valid for particle separation. The forces involved are primarily based on chemical potential gradient, electrical potential gradient, centrifugal force field, gravity and magnetic field. The physical systems involved can be two immiscible phases, membranes or single-phase systems; further the separation involved may include chemical separation or particle separation. There may be chemical reactions facilitating the development of species-specific regions. In most chemical engineering applications, the separation systems are open and there is bulk flow in and out of the separation system. The interactions of the direction of the bulk flow with the direction of the species-specific force(s) introduce four major types of separation device/operational configurations: bulk flow parallel to the force(s); feed-phase containing bulk flow perpendicular to the force(s); countercurrent, cocurrent or cross flow of two bulk phases/regions perpendicular to the force(s); continuous stirred tank separator. Couple these with a few additional operational aspects such as reflux, recycle, time-dependent operation, cascade etc., bulk of the separation universe becomes quite clear and understandable.