CONTINUOUS ESTIMATION OF PARTICLE-SIZE USING A FLUIDIZED-BED WITH A VERTICAL SLOT

When particulate solids flow through an opening, the effective dimensi ons of the opening are smaller than the actual dimensions by an amount that is proportional to particle size. This applies to both unfluidiz ed and fluidized flows. The theoretical basis is developed and a conce ptual design outlined for an instrument that exploits the particle siz e correction to opening dimensions as a method for measuring or monito ring particle size. Particles are caused to flow sequentially through two fluidized beds, the second of which has a narrow slot in its side. It is demonstrated, using apparatus configured to simulate this instr ument, that changes in particle size can be readily detected and conti nuously monitored. A good estimate of mean size can also be obtained, and it is expected that with appropriate calibration, this would be sa tisfactory for many process applications.