Dynamic Control of Reactors

In fact a chemical reactor is governed simultaneously by its heat balance and its mass balance. If we consider a single reaction of order n, we obtain a set of equations [Eqs. (11)]. 

In this system of coupled differential equations, the mass balance corresponds to the reaction rate and the heat balance is a simplified version showing only the heat production by the reaction and the heat removal by the cooling system, both terms resulting in heat accumulation. This system presents the property of parametric sensitivity, meaning that a small change in one of the parameters may lead to dramatic changes in the solution of the system of equations, that is, in the behavior of the reactor. This is an old [10-12], but always real, problem [13, 14]. This behavior may be observed for batch reactors and for tubular reactors (plug flow reactors) and also for bed reactors [15,16]. Calorimetric methods make it possible to 

A cold branch operating point. B instable operating point. 

In such cases, the temperature of the reactor may jump from the low-temperature solution to the high-temperature solution, which can be catastrophic if the reactor is not designed to be operated under these conditions. This problem was extensively studied by Ray and co-workers [20]. 

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