Analysis of energy flows by using pinch analysis

The principles of Pinch Technology which are stemming from thermodynamics have changed dramatically the design process of industrial heat using plants. At the time when Pinch Analysis gained attention in the early eighties, brute force computing using MINLP algorithms to identify the most economic heat exchanger network for the multiple use of energy in a plant was not be possible for even small scale problems. Therefore it was important to reduce the number of possibilities to be evaluated by using the first and second law of thermodynamics in an effective manner. The main elements developed, which have given the name to the Pinch Analysis, are the composite curves (CC) and the grand composite curve together with the Pinch Design Rules to achieve minimum heating and cooling demand for a given minimum temperature difference. Pinch Analysis made its way into the design process very quickly. A major advantage of Pinch Technology against black box process optimisation is the gained understanding of the process heat flows. The Pinch design rules can be easily applied and lead often to new ideas for changing process condition to enable for an increased heat recovery. As an example, results of a Pinch Analysis of a fertilizer process are presented.