Retrofit of heat exchanger networks is an important area of process design, not only as a means of improving the energy efficiency of a process, but also when modifying a process for other purposes, which affect the conditions of the existing network. Several approaches have been developed for the design of heat exchanger networks in grass root systems. However, these methods are not directly applicable in retrofit situations. In retrofitting of heat exchanger networks, the relative importance of various parameters, such as distance between streams, material requirements, and pressure drop costs, differ compared with grass root design and other approaches are necessary. This paper presents a method that takes the above mentioned aspects into account. It's most interesting application is in retrofit of heat exchanger networks.Another important feature of this method is the possibility to calculate the design of each match as optimally as possible concerning pressure drop and heat exchanger area. It is also possible to take into account restrictions concerning pressure drop and free available pressure drops of the streams.A case study is included based on data from a pulp and paper mill to study the impact of the parameters mentioned above. The most important parameters identified was the heat exchanger area and piping costs. Pressure drop costs contributed by about 15% of the total cost.
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