Petri-net-based strategy to synthesize the operating procedures for cleaning pipeline networks

Cleaning the pipeline network is a routine operation in almost every chemical plant. Traditionally, the tasks for synthesizing the needed operation steps are carried out manually on an ad hoc basis. This approach is often time-consuming for a complex industrial process and, furthermore, the resulting recipe may be error-prone. The aim of this paper is thus to develop a systematic strategy to generate correct cleaning procedures efficiently. Specifically, the proper material-transfer routes are selected on the basis of the Petri-net representation of all possible paths in the pipeline network. The operation steps for transporting detergent along a designated route can be identified from the simulation results obtained with the Petri-net model of the entire system. By connection of this system model with a net representing the schedule manager, a recipe can be produced accordingly to achieve a multiroute sequential/concurrent schedule. A realistic example is presented at the end of this paper to demonstrate the effectiveness and correctness of the proposed strategy.