Heat exchanger network retrofit considering pressure drop and heat-transfer enhancement

For the heat-exchanger-network (HEN) retrofit project to be successful it s hould satisfy not only a specified heat-recovery target but also pressure-d rop constraints. The problem of dealing with the pressure-drop aspects is v ery complex, since there are many options that affect pressure drop. To int egrate these options more systematically and solve this problem more effect ively, a decomposition strategy is proposed. At the first stage the unit-ba sed model is used to indicate which units require additional area. In the s econd stage, special attention is paid to these units, where area distribut ion, shell arrangements, the use of heat-transfer enhancement, and other op tions are optimized for these units. At the same time, the units without ad ditional area requirement are modeled using simple models. Thus units with and without additional area requirements are treated differently during opt imization, By doing this, the pressure drop can be calculated accurately wh ile the overall model remains simple and easy to solve. Heat transfer enhan cement is a very attractive option for HEN retrofit, since it call effectiv ely eliminate or reduce the additional surface area space. This will elimin ate additional piping, new shells or units, and their required space, which lead to much lower modification costs and less implementation time.