ANALYSIS OF DYNAMIC-MODELS FOR STRUCTURAL INSIGHT AND MODEL-REDUCTION.2. A MULTISTAGE COMPRESSOR SHUTDOWN CASE-STUDY

In this second paper, the three structural measures which have been de veloped are used in the modelling of a three stage centrifugal synthes is gas compressor. The goal of this case study is to determine the ess ential mathematical structure which must be incorporated into the comp ressor model to accurately model the shutdown of this system. A simple , accurate and functional model of the system is created via three str uctural measures. It was found that the model can be correctly reduced into its basic modes and that the order of the differential system ca n be reduced from 51(st) to 20(th). Of the 31 differential equational 21 reduce to algebraic relations, 8 become constants and 2 can be dele ted thereby increasing the algebraic set from 70 to 91 equations. An i nterpretation is also obtained as to which physical phenomena are domi nating the dynamics of the compressor add whether the compressor will enter surge during the shutdown. Comparisons of the reduced model perf ormance against the full model are given, showing the accuracy and app licability of the approach. Copyright (C) 1996 Elsevier Science Ltd