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A method to detect and control fully fluidized conical beds with a wide size distribution of particles in the vicinity of the minimum fluidization velocity

Mele Jernej (Bosio d.o.o., Štore, Slovenia)
Golobič Iztok (University of Ljubljana, Faculty of Mechanical engineering, Ljubljana, Slovenia)
Senegačnik Andrej (University of Ljubljana, Faculty of Mechanical engineering, Ljubljana, Slovenia)

This article presents a new method for the control of a gas-sand conical fluidized bed with a wide size distribution of particles. A two-step procedure was developed and experimentally tested. The minimum velocity for full fluidization is determined by a new statistically based method and then the fully fluidized state is initiated and controlled. It is proven that the characteristics of the pressure drop vs. fluidization velocity remain practically the same for different bed heights and over a wide size distribution of particles. The method analyses the recorded pressure drops with a histogram. The minimum velocity for full fluidization is determined as the smallest fluidization velocity from the histogram bin with the highest density. Finally, it is also proved that the fluidization velocity is a reliable parameter for controlling the fluidization. The method was used to control fully fluidized beds at the minimum gas velocity in a pilot FICFB gasificator.

Keywords: cnical fluidized bed, minimal fluidization velocity, parameter identification, process control