A number of factors have contributed to increased pressure on plant operating efficiency in the chemical processing industry. These factors include more stringent environmental and safety regulations, global economic pressures and downsizing of many support services in order to save money. Control performance monitoring is a tool that is used to keep control systems performing as optimally as possible. Various performance metrics and methods exist to evaluate plant operation. In essence, however, they all refer to the same principle which is to indicate how far a plant is operating from its inherent optimum and what can be done to ensure that the gap between the optimum and the current operation is as small as possible over the longest possible period. Performance monitoring is, although well researched, not a generic, complete and specific application. Current shortcomings of monitoring applications include the following; they are process or unit operation specific and they provide local indications of performance and do not provide a plant wide evaluation of how close the plant is operating to its inherent optimum. Performance reports are usually in terms of statistical measures and graphics which are usually abstract and vague. For high level decisions making (on operation end economic investment) simple and quantifiable measures are needed that are repeatable and transparent. The focus of this project was to develop and implement a regulatory performance monitoring structure for real-time application on an industrial pilot scale distillation column. The structure was implemented by means of two graphical interfaces. The first interface provides a holistic plantwide indication of performance and indicates sources of poor performance in the regulatory control structure. The plantwide interface includes a proposed plant wide performance index (PWI) that reduces operational efficiency to one specific number. The second interface supplements the plantwide interface by providing statistical information on individual loop performance. The individual loop interface is a tool to locate causes of poor performance in the regulatory control structure to aid controller and plant maintenance.
Dissertation (MEng (Control Engineering))--University of Pretoria, 2007.