Runaway criterion in fixed bed catalytic reactors with radial temperature profile

The discrepancy between pseudo-homogeneous one-dimensional model and pseudo homogeneous two-dimensional model is studied. It is found that there are gr eat differences between two models. This paper compares the maximum and min imum values of the radial temperature in the hot spot in case that a single exothermic reaction is carried out, a correlation is obtained with pseudo- homogeneous one-dimensional model to describe the entire reactor behavior. A new runaway criterion, based on the occurrence of inflection in the hot s pot locus, is developed for the case of pseudo-homogeneous two-dimensional model. This criterion predicts the maximum allowable temperature for safe o peration and the regions of runaway, respectively. The calculated results s how that, compared with the results based on pseudo-homogeneous one-dimensi onal model, runaway will easily occur when the radial temperature gradient has to be considered.