The Nature of the Problem

Although isothermal conditions are most useful for the measurement of kinetic data, real reactor operation is nonnally nonisothennal. Within the limits of heat exchange, the reactor can operate isothennally (maximum heat exchange) or adiabatically (no heat exchange); recall the limits of reactor behavior given in Table 3.1.1. Between these bounds of heat transfer lies the most common fonn of reactor operation-the nonisothermal regime (some extent of heat exchange). The three types of reactor operations yield different temperature profiles within the reactor and are illustrated in Figure 9.1.1 for an exothennic reaction. If a reactor is operated at nonisothennal or adiabatic conditions then the material balance equation must be written with the temperature, T, as a variable. For example with the PFR, the material balance becomes:

Energy Balances

Nonisothermal Batch Reactor