Coupling design of interunit heat integration in an industrial crude distillation plant using pinch analysis

In this study, pinch analysis was performed on three separate, efficiently-operated, preheat trains (PHTs) of industrial crude distillation units (CDUs). It was revealed that, although each individual PHT was approaching maximum energy recovery, interunit coupling could potentially be considered to make further progress. Simulative trials found that an extra 9.58% energy consumption was reduced through including innerunit optimization into interunit design. A necessary economic evaluation verified that energy cost minimization recovered the investment within a reasonable payback period. This case study illuminated a thought train for an innovative pathway-better heat sources-sinks matched with the least revamping in an extended-energy system-which might allow numerous similar refineries in China to improve their energy supply. Essentially, this study also presents a proposal for optimization of the entire heat exchanger network of three separate CDUs in a northern China bitumen enterprise.