DISTILLATIONTOWERS CONTROL

WHAT IS DISTILLATION ?

Distillation is a method of separating mixtures based on differences in their volatilities in a boiling liquid mixture.

Distillation is a unit operation, or a physical separation process, and not a chemical reaction.

Definitions

Boiling pointThe temperature at which its vapour pressure is

equal to the pressure of the gas above it.

Vapour pressureThe pressure of the vapour resulting from

evaporation of a liquid (or solid) above a sample of the liquid (or solid) in a closed container.

Types of Distillation Towers

High pressure

Low pressure

Vacuum

Types of Distillation Towers Trays typeValve – Bubble Caps – Sieve Packing typeRushing rings Saddle packings

Types of Trays

Valve Trays

Type of trays

Bubble Caps Trays

Types of Trays

Sieve Trays

Typical Trays Distillation Tower

Typical Packing Distillation Tower

DISTILLATION TOWER CONTROL

Feedback Vs Feed-forward

Feedback control is not predictive Requires operators to change set points to optimize system

Feed-forward control basically involves a control equation which has certain corrective terms which account for predicted disturbances entering the system.

ADVANCED PROCESS CONTROL

Benefits of APC

Ability to reduce process variation and optimize multiple variables simultaneously

Maximize the process capacity to unit constraints

Reduce quality giveaway as products closer to specifications

Ability to offload optimization responsibility from operator