Distillation column Instrumentation

Introduction:

Distillation is the most widely used separation process in the chemical industry. Distillation is the process of separating a mixture of two or more miscible liquids into their pure components. Separation of components from a liquid mixture by distillation depends on the difference in boiling points of the individual components and also on the concentrations of the components present. The distillation process therefore depends on the vapor pressure characterized by the liquid mixture.

Why should the various components of a mixture be separated?

· Remove unwanted impurities.

· Removes substances harmful to our health.

· Receive pure substance.

· Separates two different but useful components.

Distillation column type:

1) Batch column:

In batch operation, the column feed is fed discontinuously. The column is fed a “batch” and the distillation process is run. Once the desired task is completed, the next batch of feed is introduced.

2) Continuous columns:

The continuous column, on the other hand, processes a continuous stream of feed. No interruptions unless there is a problem with the column or surrounding process unit. They can handle high throughput and are the most common of the two types.Focus only on the pillars of this class.

Continuous columns can be further classified as follows:

· Type of feed to be processed:

§ Bi-Component Column — Feed contains only two components.

§ Multi-Component Column — Feed contains more than one component.

· The number of product streams they have:

§ Multi-Product Columns — Columns have more than one product stream

Main Components of Distillation Columns

· Vertical Jacket: Where separation of liquid components takes place.

· Columns: Column internals such as trays/plates used to improve component separation.

· Reboiler: A reboiler is a type of heat exchanger used to provide the heat required for distillation.

· Condenser: Overhead vapor exiting the tower is sent to a cooler or condenser and collected in an accumulator.

· Backflow: A backflow drum for collecting condensed vapors so that liquid backflow can be reused.

Distillation Applications:

· Solvent Recovery:

o Expensive solvents are often used to extract active chemical components from herbal medicines, but distillation makes the process economical by recovering the expensive solvents. Solvents used can have hazardous effects if released into the atmosphere.

o Distillation with recovery minimizes operational hazards.

· Volatile Oil Extraction: Many volatile oils such as clove oil, fennel oil are obtained by steam distillation.

· Manufacture of official formulations Official formulations such as distilled water and water for injection are manufactured by distillation.

· Purification: The distillation process can be used to produce a pure product

· A crude oil refinery is a group of industrial facilities that turns crude oil and other inputs into finished petroleum products. A refinery’s capacity refers to the maximum amount of crude oil designed to flow into the distillation unit of a refinery, also known as the crude unit.

The diagram above presents a stylized version of the distillation process. Crude oil is made up of a mixture of hydrocarbons, and the distillation process aims to separate this crude oil into broad categories of its component hydrocarbons, or “fractions.” Crude oil is first heated and then put into a distillation column, also known as a still, where different products boil off and are recovered at different temperatures.

Lighter products, such as butane and other liquid petroleum gases (LPG), gasoline blending components, and naphtha, are recovered at the lowest temperatures. Mid-range products include jet fuel, kerosene, and distillates (such as home heating oil and diesel fuel). The heaviest products such as residual fuel oil are recovered at temperatures sometimes over 1,000 degrees Fahrenheit