In a thermal station which is part of a chemical plant, both high- and low-pressure process steams can be produced. A typical thermal station has constraints associated with steam pressure

and usage. The following economic and process model is developed for the station producing high-pressure steam, p1, and low-pressure steam,Pz: \text { Profit: } \quad f=0.16 p_{1}+0.14 p_{2} \text { Subject to: } \quad p_{1}+p_{2} \leq 20 p_{1}+4 p_{2} \leq 60 4 p_{1}+3 p_{2} \leq 72