Particle Growth in Fluidised Bed Granulation

N. Balasubramaniam and C. Srinivasakannan

Abstract
A series of batch experiments are carried out in a fluidized bed granulator with malic acid to understand the growth mechanism and the growth rate of particles with respect to the operating parameters such as the flow rate of the spray solution, temperature and flow rate of the fluidizing air, the concentration of the solution and the seed particle diameter. The increase in flow rate or the increase in concentration of the spray solution is found to increase the growth rate of particles. The increase in temperature and flow rate of the heating medium does not affect the growth rate of particles, however it indirectly helps the process by facilitating to operate at higher liquid flow rates. The seed particle diameter has a major role to play on deciding the particle growth mechanism. The larger seed particles favour coating process, whereas the smaller particles favour agglomeration. Since smaller seed particles tend to agglomerate and grow faster, higher solute throughput could not be achieved. Hence a special type of agitator is designed to promote coating phenomena with smaller seed particles. Thermal efficiency of around 80 % is achieved.

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Keywords
Fluidization, granulation, particle growth, coating, agglomeration