Significant energy savings can be achieved in some manufacturing enterprises through process integration. But in certain cases, the optimization of energy utilization should be combined with many items, such as the rational structures of energy consumption, the influence of seasonal variations, and application of waste heat recycling technologies, etc. This paper shows an example for process synthesis extending traditional pinch analysis according to the situation of energy utilization in different seasons. Seen from the optimization analysis, the energy consumption will decrease apparently through the heat integration over the year and the adjustment of the consumption structure of energy. (C) 2010 Elsevier Ltd. All rights reserved.