Influence of utility prices on the optimum process structure was studi
ed. Different prices of utilities and increasing investment costs (inf
lation) over three different decades have been considered. In one deca
de the fuel price was very low while in another one it was very high.
Process structures in these decades were derived using pinch and nonli
near programming methods on a hydrodealkylation of toluene process wit
h diphenyl recycled. The results showed that structures differed in th
e three decades because of different prices and for that reason a comm
on process configuration, usable both for eventual future high or low
fuel prices, could be developed.