Search

Combined execution of realistic models of large highly integrated process flowsheets using conventinal simulation strategies is prohibitive in terms of computation time and computer storage requirements. Hierarchical solution strategies based on concept first proposed by Rosen discussed. The process flowsheet is viewed as consisting of a collection of process sections each involving multiple equipments items. Process section models are assumed to be assembled using conventional modular simulators. Linear material balance models of various levels of aggregation are proposed for use at the overall process level. The balance models are solved using a novel non-iterative solution method. Trials results indicate that a two level strategy employing sequential single pass execution of the section simulations coupled with solution of a partially aggregated process material blance model which incorporates recycles between sections as well as recycles internal to sections requires least time. Implementation of the mehtod and the required file structure are discussed.

A methodology for machine layout of process streams involving multiple directional changes given the equipment layout and stream connection information is formulated. Also considered are the drawing of these streams and of various process equipment symbols as well as the layout and drawing of peripheral flowsheet symbols and messages. The key concepts involved are the use of a coded grid representation of the drawing space, a structural classification of stream configurations, efficient constructions for generating stream paths, and the formulation of a ranking of stream paths. A program package implementing the methodology which includes a simple yet flexible data structure for generating and storing equipment symbols is discussed and example flowsheet are given.

A computer aided methodology is presented for determining the positions of equipment symbols in a flowsheet given only the equipment connection information. A two pass logic is used. In the first pass the location of process sections is determined by reducing the process section level flowsheet and generating a mesh structure using a modification of Rubin's algorithm. The approximate dimensions of each section are determined using a depth first search, and, the locations of the process section centroids are selected heuristically. In the second pass, the equipment symbols are positioned within the sections taking into account external equipment connections to other process sections as well as the flow patterns within the section. An experimental program has been developed and some test examples are presented.