15.4. The Control and Optimization Hierarchy
The actual operation of a chemical manufacturing company involves decisions and actions that occur at a number of levels and timescales, as shown in Figure 15-15. At the corporate level, allocation decisions are made. Market demand projections, raw material availability, and past operating costs are used to set long-term plans for corporate-wide optimization. These decisions are typically made on an infrequent basis—weekly, monthly, or quarterly. Often these decisions are made using linear programming (LP) techniques. This information is passed to the plant level.
Figure 15-15. Corporate operating levels.
At the next level are plant decisions about allocation among various plant operating ...