WRONG-WAY BEHAVIOR OF PACKED-BED REACTORS - INFLUENCE OF REACTANT ADSORPTION ON SUPPORT

Wrong-way behavior refers to a large transient temperature increase caused by a sudden reduction in the feed temperature or increase in the feed rate to a packed-bed reactor operating at an intermediate or high level of conversion. This dynamic temperature rise may be affected by reactant adsorption on the inert catalyst support. The wrong- way behavior usually leads to formation of a downstream-moving temperature front. In such cases, reactant adsorption tends to moderate and decrease the maximal transient temperature of these fronts. However, when the wrong-way behavior generates an upstream-moving temperature front, reactant adsorption may substantially increase the temperature rise over that attained in its absence and ignite the reactor. Reactant adsorption may also lead to surprising dynamic effects upon changes in feed velocity.