Before we move on to dynamics and control, it may be useful to briefly explore the impact of some of the design parameters on the yields and the boiling points of the various products. This insight will be applied when a control structure is developed to maintain the several specifications in the face of disturbances.
In setting up the steady-state design, we have specified all the equipment parameters (the number of stages and locations of feeds and withdrawal points). In addition, we have specified 10 operating variables; that is, there are 10 operating degrees of freedom in this pipestill process:
1. The 95% boiling point specification on the heavy-naphtha stream is 350°F.
2. The diesel 95% boiling point specification is 640°F.
3. The flowrate of AGO is 8500 b/d.
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