1. Heat transfer control

1.1 Thermal characteristics of reactors

Temperature is a sensitive parameter of reaction rate, whose kinetic constant is expressed by Arrhenius' law.

A practical rule of thumb is to consider that the speed of a reaction is multiplied by 2 when the temperature is increased by 10°C. This rule is in fact only correct for an activation energy value of 58 kJ/mol at 316°C, which is a common value in organic chemistry. This means that the reaction rate changes by around 7% for a variation of 1°C.

Given the limited thermal capacity of a medium-sized or large reactor, it is common to observe temperature gradients of a few degrees in the medium, which can lead to a variation in kinetics of up to 50%. This is particularly true of endo- or exothermic...