Operational design for start-up of chemical processes

Aiming at designing more operable chemical processes, this paper presents an operational design methodology for the case of process start-up which evaluates and improves a process how diagram (PFD) into an operational flow diagram (OFD) by modifying the process structure, adjusting the process behavior and adding more facilities. An important controlled group unit (CGU) concept is introduced, which can be operated independently from other parts of the process. This CGU concept makes it convenient to decompose the whole process into CGUs so that the complicated design problem can be narrowed down and simplified. A multi-level blackboard architecture is used to implement such a design methodology which supports an interactive environment for engineers. Object orientation is used to implement the knowledge sources which improves the blackboard performance. Finally, the methodology is illustrated by a simple example and then is evaluated by an industrial hydrogen-desulfurization process design case study. (C) 1997 Elsevier Science Ltd.