Retrofitting industrial Heat Exchanger Network based on pinch analysis

A systematic but simple pinch-based retrofit procedure is developed to lower the utility consumption levels of any given industrial Heat Exchanger Network (HEN) under new minimum temperature approach at the cost of minor capital investment. This work is an extended and improved version of our previous work (Li and Chang, 2010). New visualized identification method for cross-pinch heat load is proposed to cover the case that phases change in the cross-pinch heat exchanger. Main characters of industrial HENs which are large scale, varied heat capacity flow rate and multiple pinches are fully addressed. Specifically, each cross-pinch exchanger is identified and those exchanges with large loads are removed first, and then, their heat loads on the hot and cold streams are both divided according to pinch temperatures. Next, at either side of or between the pinches, the divided heat loads on each stream are combined to remove small heat loads and matched according to a systematic procedure derived from simple pinch analysis. Note that modifications are focused on those cross-pinch matches and utility exchangers, which greatly simplifies the retrofitting procedure of an industrial HEN. An industrial case of Crude Oil Preheat Train (COPT) is retrofitted to illustrate the effectiveness of the proposed procedure.