DESIGN MODIFICATIONS AND PROPER PLANTWIDE CONTROL

First, an unifying concept: the Selfregulating Structure Philosophy is explained based on i) the decomposition of the plantwide control prob lem, ii) the plantwide component inventories and iii) the rationalizat ion of the unit control strategy. After this, the optimum steady-state distillation control problem is evaluated based on this concept and t he impact of the extensive process diversity on the distillation colum n control is reviewed. From the viewpoint of controllability those pro cess modifications are proved to be beneficial by which we can create new design variables, Second, the optimum steady state plantwide contr ol problems are evaluated and illustrated on case studies, then a proc edure for control system design is outlined which gives guide-lines to the designer how and in which phases of the design process the differ ent aspects of operability should be considered.