ABSTRACT

This chapter develops simple common sense heuristics/guidelines for sustainable operation of highly integrated chemical plants. It also develops the heuristic that the control system should be designed to directly/indirectly hold the recycle rate in a recycle loop by adjusting an inflow/outflow from the recycle loop. For maximizing production with the bottleneck constraint inside the recycle loop, this heuristic allows locating the throughput manipulator (TPM) at the bottleneck constraint to eliminate back-off from the hard bottleneck constraint. The chapter argues that smart management of economically important unconstrained degrees of freedoms (DOFs) is necessary to ensure sustainable energy-efficient process operation. It illustrates the control issues introduced by material/energy recycle and develop very simple commonsense guidelines to address them. The chapter reports quantitative case-study results done previously in research group to demonstrate the significant economic/sustainability benefit of the application of these guidelines.