This paper considers the design of integrated processes for the conver
sion of a set of raw materials to a set of end products utilising a gi
ven set of reaction and separation unit operations. It advocates the u
se of detailed unit operation models to ensure the practical realisabi
lity and optimality of the derived designs. It also demonstrates that,
provided the models fulfil a certain condition, the number of discret
e alternatives that need to be considered is relatively small. An exam
ple of the application of the method to the design of an ethylbenzene
production process is presented.