Determination of the Critical Particle Entrainment Diameter in a Fluidized Bed Reactor

Currently, interest in using fluidized bed reactors in chemistry, petrochemistry, and oil refining does not stop. There remains a problem that needs to be solved and associated with the separation of the dispersed phase from gas mixtures leaving the fluidized bed of the reactor is important, since the stock of solid particles decreases over time, which affects the efficiency of fluidization. Cyclones are usually used to return solid material back to the layer. In this study, we propose an alternative separator for the upper part of a fluidized bed reactor. The developed separator with arc-shaped elements is used to separate solid particles and gas. The particles hit the elements, then move along the V-shaped partitions into the hopper and return to the fluidized bed. Since the fluidized bed behavior depends on the material properties, the purpose of the study was to determine the critical size of particles suspended in the reactor gas stream above the bed, which will further determine the separator efficiency and design a vertical space above the bed to prevent large amounts of bed material from being carried out of the reactor by the gas stream. Because of the research conducted at the experimental installation, the efficiency of the device was determined depending on the air velocity at the entrance to the installation and the particle size. We carried numerical studies out in the package of applied mathematical modeling. Because of the research, the rates of the beginning of fluidization and entrainment of the dispersed phase for particles of different densities were determined. The particle size was determined, which was carried up from the fluidized bed by the gas flow, and had to get into the developed separator with arc-shaped elements, and with sufficient efficiency for this. For the reactor inlet velocity in the range from 0.26 m/s to 0.74 m/s, a critical diameter was obtained at a density of 3580 kg/m3 in the range from 52.5-98 microns, for a density of 7000 kg/m3, the particle range was from 37.1 microns to 69.2 microns.