Chapter 6

Constraints

For the operation and control of a distillation column, there
are a number of constraints that must not be violated. Some of
the constraints are mechanical and hydraulic limits, and others
are mass transfer separation capability limits.
Learning Objectives
When you have completed this chapter, you should be able to
1. Understand the maximum constraints for pressure drop
and flooding, boilup, reflux, feed, and distillate flow rates
2. Understand the mass transfer rate limitations in the stripping section and the rectification section of a distillation
column
6.1 Mechanical and Hydraulic Constraints
The most familiar mechanical constraint in the distillation system is the pressure drop and hydraulics associated with flooding. The main process variable that affects flooding is the vapor
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