Operating Pressure Basis - Distillation Tower

[Dlew]

What are the basis of operating pressure value for a distillation tower?

[opo21]

Actually, there are process design basis deciding upon selecting the right operating pressure for distillation tower.
Factors which are required to be considered include the following:
a. Separation requirements (vapor liquid equilibrium) - pressure affects the boiling point
b. Condenser & cooling medium availability - with low selected pressure, overhead vapor may not condense with cooling water, refrigeration may be required
c. Reboiler Heat Source & Energy Optimization - to have high pressure, higher steam energy through reboiler is needed
d. Thermal stability of the process fluids itself play an important role to select the operating pressure
e. Pressure drop through column internals - another factor to be considered

[jeem]

Quite a subjective question however operating pressure is determined by optimizing:
Separation efficiency
Energy consumption
Condenser feasibility
Fluid thermal stability
Column size & cost
Utility availability
Safety & equipment limits