An improved design method for retrofitting industrial heat exchanger networks based on Pinch Analysis

Energy integration relies on matching process hot streams with process cold streams, and utilities are only introduced to balance the deficit in energy consumption. A systematic but simple Pinch Analysis (PA)-based retrofit approach is proposed to lessen the utility consumption of any industrial heat exchanger network (HEN) under new minimum temperature approach (Delta T(m)s) at the cost of minor capital investment. This work is an extended and improved version of our previous work (Li and Chang, 2010). Elaborate visualized tool of T-H diagram for identification of cross-pinch heat load is proposed to fully address 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 or match is identified and those matches with large cross-pinch loads are disconnected first, and then their heat loads on the hot and cold stream side are split according to pinch temperatures. Next, at either side of or between the pinches, the divided heat loads on each stream are combined and matched according to a systematic Pinch Analysis (PA) based procedure. Retrofit modifications are focused on those cross-pinch matches and utility exchangers, so the retrofit procedure of an industrial HEN is obviously simplified. An industrial case of Crude oil preheat train (COPT) is retrofitted to demonstrate the effectiveness of the proposed approach. (C) 2019 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.