CC-97-136 LARGE CRUDE UNIT MWLTIVARIABLE CONTROLLER

Description:

A single multivariable DMC controller with 37 independent variables and 94 dependent variables is being used to control two atmospheric crude distillation columns and a vacuum column. Substantial benefits are achieved by using a single large controller instead of three smaller controllers, because the single controller is able to exploit the interactions between the columns as part of the control strategy. A large controller raises significant maintenance and support issues; however these issues can be resolved, both by careful controller design and by developing support tools and techniques. This paper focuses on these design features and support issues.