Distillation column how does it work

Piping Systems. Additional Process Systems. Modular Skid Fabrication Advantages. Pilot Plants. Demonstration Plants. Production Plants. We are a St. Contact an Engineer View Sales Deck. Specialty Chemicals. Other Sanitary. Other Industrial. Engineering Capabilities. Unit Operations. Search Search. What is a distillation column? How much does a distillation column cost?

Some specific factors that can increase custom distillation column cost include: Feed composition — mixtures with similar boiling points or that contain azeotropes or chlorides are harder to separate and may result in a more expensive system Organics and other sensitive materials may require operating under vacuum to avoid breaking down too quickly.

While this reduces the required heat input, creating a vacuum or taking other precautions to prevent feed breakdown can add expense Required operating pressure — while this is something we work on with you, the higher the required operating pressure in the column the more expensive the column will be. A schematic of a typical distillation unit with a single feed and two product streams is shown below:. The liquid mixture that is to be processed is known as the feed and this is introduced usually somewhere near the middle of the column to a tray known as the feed tray.

The feed tray divides the column into a top enriching or rectification section and a bottom stripping section. The feed flows down the column where it is collected at the bottom in the reboiler. Heat is supplied to the reboiler to generate vapour.

The source of heat input can be any suitable fluid, although in most chemical plants this is normally steam. In refineries, the heating source may be the output streams of other columns. The vapour raised in the reboiler is re-introduced into the unit at the bottom of the column. The vapour raised in the reboiler is re-introduced into the unit at the bottom of the column.

The liquid removed from the reboiler is known as the bottoms product or simply, bottoms. The vapour moves up the column, and as it exits the top of the unit, it is cooled by a condenser. The condensed liquid is stored in a holding vessel known as the reflux drum. Some of this liquid is recycled back to the top of the column and this is called the reflux. The condensed liquid that is removed from the system is known as the distillate or top product.

Thus, there are internal flows of vapour and liquid within the column as well as external flows of feeds and product streams, into and out of the column. Out of the base flows some of this liquid, some of which is heated in the re boiler and returned to the column. This is called the boil up.

Photo of crude oil fractionating column. Demonstrates the stacked plates. Some vapor escapes from the top of the column and is returned to a liquid state in the condenser. Some of this liquid is returned to the column as reflux, and the remainder is the top product or distillate.

Vapor and liquid phases on a given plate approach thermal pressure and composition equilibrium to an extent depending upon the efficiency of the plate.