Retrofitting of a heat exchanger network for the styrene monomer plant

Abstract

Many chemical plants consume large amounts of energy and their energy costs contribute a significant portion of the total operating cost. Heat exchanger network has been incorporated in the plants to reduce these energy costs. Well-designed heat exchanger network can reduce the total operating cost. The improved heat recovery system is very important for the styrene monomer plant, because the styrene monomer process has high temperature endothermic reactions, and the heat of reactions is supplied by high temperature steam utility. Due to this reaction heat, lots of cold utilities are also required to cool down the effluent of the reactor for downstream processes. This plant consumes much energy cost, which is almost one half of the total operating cost. In this study, the current heat exchanger network of the styrene monomer plant was analyzed by pinch analysis. The analysis results show that opportunities for improving the current heat exchanger network exist. Using this analysis result, three heat exchanger networks are proposed. All new heat exchanger networks have better performances than the current one. Among them, the evolved system 2 has the best economical efficiency.