The aim of the diploma-work is the creating of a computer program for process integration and using it in a concrete industrial case. The program-system contains targeting and design procedures for grass-root design and retrofit of heat exchanger networks including detailed designing of shell-and-tube heat exchangers with segmental or helical baffles, respectively. In the first part a procedure for consideration of pressure drop in process integration and heat exchanger design is described. Case study of the retrofit of an existing hydrogenation process follows. Furthermore, the integration of a furnace by using a detailed furnace calculation is shown. In this part we will go into the interdependence of air pollution reductions and energy savings. Because of shortage of space, only selected parts of the work will be represented in this short report.