CHAP. 9: CHEMICAL KINETICS [CONTENTS] 321
9.7 Chemical reactors.
A chemical reactor is a device, most often industrial, in which a chemical reaction takes place.
9.7.1 Types of reactors
Based on the way of the reactants transport, we distinguish the following types of reactors:
a) Batch reactors—reactants are put in the reactor of a fixed volume (autoclave, beaker)
and products are withdrawn after the reaction is terminated.
b) Flow reactors—reactants enter the reactor and products (more accurately a mixture of
products and reactants) are withdrawn continuously. Flow reactors are further classified
as:- plug flow reactors—the reactants flow laminarly, the concentration of the prod-
ucts changes with their position (it is zero at the entry and the highest at the exit); - stirred flow reactors—the concentration of the reactants is the same in all parts
of the reactor.
Based on the thermodynamic conditions under which the reaction takes place, we distinguish
the following three types of chemical reactors: - isothermal,
- adiabatic,
- polytropic.
9.7.2 Batch reactor
Here we are interested in the relations between the reactor volumeV, the amount of substance
of the productnp, and the reaction timeτ. The ratio of the amount of substance and volume is
the concentration,cp=nP/V. The relations between the concentrations of the reactants and
time—integrated forms of kinetic equations—were discussed in sections9.2,9.4and9.5.