PINCH ANALYSIS - A STATE-OF-THE-ART OVERVIEW

Through much of its fifteen year history Pinch Analysis has been somew hat controversial. Early on, as Pinch Technology, it introduced simple concepts in a field and an era otherwise known for complex mathematic al methods. Reports from first industrial applications37,42,74 claimed design improvements so large as to invite incredulity. Moreover, Pinc h Analysis was commercialized early in its development when there was little know-how from practical application. This led to several commer cial failures and many vested interests. To this day, opinions remain divided. Morgan (M. W. Kellogg) reports that Pinch Analysis significan tly improves both the 'process design and the design process''. Steinm eyer (Monsanto) is concerned that Pinch Analysis may miss out on '... major opportunity for improvement ...'75. As is often the case when th ere is a difference of opinion, different parties have different data. Some of the concepts of Pinch Analysis are widely known, others are l ess well known. Experience with practical application varies. Some org anizations have successfully integrated the approach into the design p rocess, others rely on one or two technical experts. In addition, Pinc h Analysis has undergone evolution making it difficult for the casual observer to come to an up-to-date assessment. It has evolved from the design of heat exchanger networks into a general methodology for the d esign of integrated systems ranging from processes to Total Sites. The present paper attempts to give a state-of-the-art overview. It gives a summary of key established concepts with special emphasis on those c oncepts which are less well known than others. This is followed by a d escription of eight recent developments. Some of these developments sh arpen the focus of the established concepts, others widen the scope. A ll of them follow the established pattern of Pinch Analysis of setting targets prior to design. The eight developments are: Pressure Drop Op timization Batch Process Integration Multiple Base Case Design Water a nd Waste Water Minimization Distillation Column Profiles Total Site In tegration Low Temperature Process Design Emissions Targeting The paper concentrates on the essence not the detail. Case studies are describe d and scope and impact of practical applications are assessed. For det ails of methodology, the reader is referred to the relevant references . To complete the overview, the paper provides a comprehensive summary of previous literature. Theory and applications are covered, and a hi storical perspective is given. The evolution of 'Pinch' is discussed a nd it is argued that the term Pinch 'Analysis' is more appropriate tod ay than Pinch 'Technology'. Pinch Analysis is used for the scoping and screening of options during targeting prior to design. The choice of utilities, capital cost optimization, changes in the-process/reactor/s eparation system, overall process emissions, etc. are all evaluated pr ior to design i.e. in analysis mode.