A prescreening and decomposition method is presented to analyse heat exchanger networks for retrofitting. The method, called Path Analysis, selects and analyses fractions from the existing network, either by heuristics or by an algorithm. By comparison of all fractions, the critical parts of the network that should be adapted can be identified. The adaptations can be done independent of the remaining network. Thus Path Analysis enables a considerable reduction of the effort in retrofit design. Meanwhile the simplest network adaptations are favoured.

Path Analysis is applied to several cases. The results for an aromatics case are presented. Using the right software tools, the engineering effort can be reduced considerably, compared with existing methods. Solutions tend to be less complex, while the profitability is sometimes higher than was expected from global analysis. With Path Analysis the retrofit design using new multi-stream heat exchangers proved to be straightforward.