2007, Flue Gas Desulfurization Technology Evaluation Dry Lime vs Wet Limestone FGD. You are starting with an updraft fixed bed, increasing the gas flow you get to a point when the forces at the particles within the bed result in an expansion of the bed, where there is no continious contact between the neigbouring particles. A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions. This is known as a packed bed reactor. As the fluid velocity is increased, the reactor will reach a stage where the force of the fluid on the solids is enough to balance the weight of the solid material. Heterogenous catalytic reactors put emphasis on catalyst effectiveness factors and the heat and mass transfer implications. A fixed bed reactor is a cylindrical tube filled with catalyst pellets with reactants flowing through the bed and being converted into products. A fluidized bed reactor suspends small particles of catalyst by the upward motion of the fluid to be reacted.
The fluidized state occurs when a fixed bed of the particulate material is penetrated in the vertical direction with fluid at sufficient velocity to break up the bed. In reality, in large scale chemical reactors, it sometimes happens that these conditions are not fulfilled. Multiphase catalytic packed-bed reactors (PBRs) operate in two modes: (1) trickle operation, with a continuous gas phase and a distributed liquid phase, and the main mass transfer resistance located in the gas, and (2) bubble operation, with a distributed gas. However, for three -phase catalytic reactors such as those employed for hydrotreating of middle distillates and heavy petroleum fractions, the reaction occurs between the dissolved gas and the liquid-phase reactant at the surface of the catalyst, and the choice of upflow versus downflow operation can be based on rational considerations regarding the limiting reactant at the operating conditions of interest (Dudukovic et al.