Distillation Control Flashcards

Flashcards on Distillation Control principles and techniques.

Distillation

A process in which the components of a liquid mixture separate through vaporization and condensation, made possible by the different vapour pressures of the liquid mixture components.

Vapour Pressure

The pressure that the gas, in equilibrium with a solid or liquid in a closed container at a given temperature, exerts.

Volatile Components

Components in a liquid mixture that evaporate more easily than others.

Binary Liquid

A liquid made up of two components.

Partial Pressure

The vapour pressure of the pure component multiplied by its concentration in the liquid mixture.

Reflux Condenser

Cools vapour, producing the tops product/distillate. Some of the distillate is used as reflux and flows back into the top stage of the distillation process.

Bottoms Product

The liquid that is drawn off from the bottom stage to maintain a constant level.

Distillation Column

The tower and its associated equipment which enables the distillation process. The column provides the necessary separation.

Column Downcomers

The path in which liquid enters and leaves a distillation column tray.

Internal Reflux

The process in which liquid leaving a tray is stripped of some of its lighter components.

Rectifying Section

The trays above the feed tray that enrich the vapour that moves up the column with the more volatile components.

Accumulator/Reflux Drum

Provides storage capacity for the distillate and returns to the column to enhance enrichment, called external reflux.

Stripping Section

The trays below the feed tray that strip the more volatile components from the liquid moving down the column.

Reboiler

Provides heat input which generates the upward moving vapout stream.

Steady State Model

Defines the distillation process with equations developed from material and energy balances.

Light Key

The more volatile component of the feed in a binary distillation.

Split (Cut)

The amount of the feed that exits the process as distillate or bottoms.

Fractionation

The amount of separation that occurs or the composition of the distillate and bottoms.

Boil Up

The degree the heat energy supplied by a reboiler controls vapour flow.

Reflux Ratio (R)

The ratio of the reflux flow to distillate flow.

Total Condenser

A condenser that condenses all the overhead vapour to a liquid.

Conventional Energy Balance

Distillation control strategies that either set the column heat input or column cooling directly to achieve the required energy balance.

Water Throttling

Manipulating the coolant flow through the condenser to control pressure in the distillation column.

Overhead Throttling

Manipulating the overhead vapour flow to the condenser to control pressure in the distillation column.

Flooded Condenser

Manipulates the condensed (liquid) overhead product flow out of the condenser to control the pressure in the distillation column.

Conventional Material Balance

Distillation control strategy that sets the distillate flow or bottoms flow directly to achieve the required material balance.

Analyzer Control

Uses online analyzers to measure and control the composition of a key component.

Dynamic Compensation

Provided by dead-time and lead-lag function blocks, which allow for changes over time.

Pump-Around

Removes hot liquid, cools it, then returns it to the tray at a higher temperature.

Flooding

The excessive accumulation of liquid inside a distillation column.

Puking

When too much reflux flow can overwhelm the downcomer causing pressure to increase until the tower ejects liquid out of the column.

Dry Trays

Trays that do not have enough liquid on them to work correctly.

Weeping

Occurs when liquid in a tray starts to leak through the vapor passages and onto the tray below.

Dumping

Where the liquid on all of the trays cascade or dump through to the base of the column.

Inert Gases

Gases that do not condense at the condenser's operating temperature and pressure.