A pilot plant study and 2-D dispersion-reactor model for a high-density riser reactor

Abstract

The radial concentration profiles of reactant concentrations in a pilot plant high-density riser propylene ammoxidation reactor were sampled and analyzed and the extreme maldistribution of the profiles were found. A two-dimensional dispersion-reactor model was proposed to simulate the selective oxidization that taken place in the riser, which considered the influences of axial and lateral gas mixing, the non-uniformity of radial solids concentration and gas-velocity profiles on the reactor. The model can successfully predict the axial and radial profiles of concentrations sampled in the pilot plant. Simulation results indicate that the non-uniformity in radial catalyst concentration and gas-velocity distribution as well as insufficient lateral gas mixing result in a significant loss of selectivity and yield of acrylonitrile. The scale-up effect and the interdependence of the reaction rate, the non-uniformity of catalyst concentration and the requirement of gas mixing are discussed in details.