Simple method for the modelling of the behaviour of a non-isothermal, non-adiabatic fixed-bed catalytic reactor

Abstract

The behaviour of a non-isothermal, non-adiabatic fixed-bed reactor used for the hydrogenation of toluene has been investigated. Although large radial temperature gradients existed in the reactor, a simple pseudo-homogeneous one-dimensional model was found to be suitable to describe the reactor behaviour. The model is based on the application of a mean cross section temperature which is derived from radial temperature profiles measured at two axial positions in the catalyst bed. Measured radial temperature profiles exhibited a parabolic shape. The mean cross section temperature applied corresponds to the temperature at the radial position (r/R) 2 = 0.5. The model equations were solved by means of the orthogonal collocation method and Gear's variable step integration algorithm. Measured radial toluene concentrations indicated that no significant radial toluene concentration gradients existed in the catalyst bed. Axial temperature and toluene concentration profiles measured during steady-state operation are compared with the corresponding profiles calculated with the reactor model.