THERMAL PARAMETER SENSITIVITY IN THE SIMULATION OF THE NON-ISOTHERMAL, NON-ADIABATIC FIXED BED CATALYTIC REACTOR—THE TWO-DIMENSIONAL HETEROGENEOUS MODEL

Publisher Website
Google Scholar
Abstract
Utilizing a two phase (fluid-solid) heterogeneous (inter-intraphase gradient) model of the fixed bed catalytic reactor, the sensitivity of thermal transport in the axial and radial directions is numerically assessed in terms of axial and radial Peclet numbers for the fluid and solid phases, the fluid-wall and wall-solid transport coefficients and local interphase fluid-solid transport in the highly exothermic case of napthalene oxidation. Axial dispersion of heat and mass in both fluid and solid phases are shown to be of little consequence in both the steady and transient modes of operation for beds of length to particle diameter ratios normally encountered i.e. L/dp > 100. Radial temperature distribution is, in contrast, sensitive to the choice of bed solid phase effective conductivity and the fluid thermal Peclet number as well as to the wall coefficients governing fluid-wall and solid-wall heat transport at that boundary. Sensitivity of the radial temperature profiles, particularly the magnitude of the “hot spot”, is also manifest with respect to the invoked inter-phase heat transport j-factor. Intraphase diffusional intrusions can be allies or enemies, depending, of course, upon the kinetic network and the above-cited transport phenomena. Parametric sensitivity is then explored with respect to feed composition, feed and wall temperatures.