Retrofitting heat exchanger networks using a modified network pinch approach

In this work, the standard network pinch approach (NPA) has been modified and extended to include some additional practical features. The modified NPA can handle complex network configurations with stream segmentation and splitting. It combines the structural modifications stage that gives the maximum heat recovery, with the cost optimization stage which optimizes the use of additional exchanger area. This combined approach reduces the risk of missing cost- effective design solutions. A new functionality is added to use different minimum approach temperatures for various heat exchangers. The possibility to have some flexibility in the supply and the target temperatures of the process streams is also considered. A new approach to deal with effluent streams (flue gases, wastewater, etc.) is proposed. Finally, a new guideline is developed to minimize the risk that a project selected in the first steps is preventing the optimal solution to be found in the following steps. An example is presented to illustrate some of the capabilities and benefits of the modified NPA.