Recipe-Based Batch Control Using High-Level Grafchart

Abstract: High-Level Grafchart is a graphical programming language for control of sequential processes. Sequential control is important in all kinds of industries: discrete, continuous and batch. Sequential elements show up both on the local control level and on the supervisory control level. High-Level Grafchart combines the graphical syntax of Grafcet/SFC with high-level programming language constructs and ideas from High-Level Petri Nets. High-Level Grafchart can be used to control sequential processes both on the local level and on the supervisory control level. The main application area of High-Level Grafchart is control of batch processes, i.e., batch control. A batch process is a special class of sequential processes frequently occuring in chemical, pharmaceutical and food industries. Batch processes and batch control is currently the subject of large interest. A recent standard, called ISA S88.01, provides an important step towards a formal definition of batch systems. The specification of how to produce a batch is called a recipe. In the thesis it is shown how High-Level Grafchart can be used for recipe strucuring. By using the features of High-Level Grafchart in different ways, recipes can be represented in a number of alternative ways. They still, however, comply with the standard ISA S88.01. The different structures are presented and discussed. A simulation of a multi-purpose, network structured batch plant has served as a test platform. High-Level Grafchart, the recipe-execution system ad the batch plant are implemented in G2, an object-oriented programming environment.