“…On the other hand, a sharp change in the enthalpy represents inappropriate feed conditioning, such as feed quality or temperature. For example, a sharp change on the reboiler side may be due to a subcooled feed, and a feed preheater with a heat duty depending on the change can be installed (1,2,16,18). Feed conditioning is usually preferred to side condensing or reboiling, since the side heat exchangers are effective at suitable temperature levels or stages only (1,2,17,18).…”