Wrong‐way behavior of packed‐bed reactors: II. Impact of thermal dispersion

A sudden reduction in the feed temperature of a packed‐bed reactor may lead to a transient temperature rise, referred to as a wrong‐way behavior. As expected, the axial dispersion of heat decreases the magnitude of the temperature excursion and prolongs the transient shift to a new steady state. In addition, the thermal dispersion may enable the wrong‐way behavior to ignite a low‐temperature steady state leading to a disastrous runaway of the reactor. Moreover, it may create a transient high‐temperature wave, which moves initially in the upstream direction. The axial dispersion of heat can lead to some behavioral features which are qualitatively different from those of a model which ignores it. The transient temperature excursion does not exceed a value, which can be estimated by a simple analytical expression.