The reboiler is an essential part of any distillation column. In this article, we are going to learn what are reboiler and what are the types of reboiler and the use of reboiler in industries.
In the previous article, we discussed are distillation process in which we had discussed the working of distillation.
To generate vapor of the substance, we need to heat the column feed material and in the column. To heat the column feed, the equipment used is a reboiler. Different types of heating media are used in the reboiler. Hence reboiler plays an important role in distillation process.
Before we get into the tutorial about what are distillation columns, let us learn what are reboiler in a distillation column.
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What are reboiler in a distillation column
A reboiler is a heat exchanger which is used to heat the feed of the distillation column and convert the liquid into vapor. Then this vapor goes from the top of the column into the condenser which is then condensed and this is how distillation works.
As the whole distillation operation works on the relative volatilities and boiling point of the substance, reboiler plays an important role in proper distillation process.
In a reboiler, different types of heating media are used such as steam, MEG (methyl ethyl glycol), hot oil and many more. Steam reboiler in which steam is used to heat the liquid is commonly used in the process.
Now, that we had learned what are reboiler and which are the utilities used in the reboiler, lets move forward and learn what are the different types of reboiler.
Types of reboiler
There are three types of reboilers that are used in the chemical industry in a distillation column but the majorly there are only two types, kettle type reboiler, and thermosyphon reboiler. Let’s proceed with the post and learn all the types of reboiler in detail along with the figures
1. Internal Reboilers
Internal reboiler are the simplest type of reboiler in which is mounted in the distillation tower itself in the bottom. They are also known as Stab-in reboiler.
As shown in the figure, In the internal boilers, heating media is circulated in the tube bundles. Internal boilers are submerged in a pool of liquid in the bottom of the distillation column and heating media (usually steam) is passed into the tube of the reboiler from top and condensate is out from the bottom. Steam then flows inside the tube, heat the column bottom liquid and convert them in vapur and liquid mixture.
In this way, internal reboiler are used into the column to perform heating and distillation process is continued.
2. Kettle type reboiler
A kettle reboiler is also known as a “submerged bundle reboiler. In a kettle-type reboiler, the process fuild which is needed to be heated remains in the shell while the heating utility such as steam or hot oil circulates in the tube.
The utility passed in the tubes of kettle reboiler, heat the liquid coved the tubes and the liquid converted into vapor goes to the top of the distillation tower.
These types of reboiler are widely used in the chemical, petrochemical, and polymer industries. These are not only used in a distillation column but also in a circulation tower where we can use brine to reduce temperature.
The only disadvantages of the kettle-type reboiler is scaling and deposition of salts or other solid material in the kettle.
3. Thermosyphon reboiler
Thermosyphon reboiler are a widely used type of reboiler in distillation column. Thermosyphon reboiler are similar to heat exchangers. As shown in the figure, the distillation column bottom is connected to the bottom of the thermosyphon reboiler.
In these reboilers, Steam or other heating media such as hot oil or MEG is circulated in the tubes of the reboiler which then heat the column bottom liquid.
The reason why these Thermosyphon reboiler are widely used it, that they don’t require any external equipment for circulation. Here the working principle is thermosyphon effect.
Thermosyphon reboiler are of two types based on reboiler orientation, vertical Thermosyphon and vertical Thermosyphon reboiler.
4. Fired reboiler
Fired reboilers are also known as a furnace which is used with the distillation column. This reboiler are divided into two sections, the convection section and the radiant section. In the bottom of the furnace, the heat source is there which is fired using natural gas, or fuel oil. The main purpose of a fired reboiler is to preheat the fluid or process.
In a fired reboiler, the pump is used to circulate the fluid in the reboiler from the top of the furnace and which is then heated in the reboiler.
5. Forced circulation reboilers
Forced circulation reboiler working is similar to the thermosyphon reboiler but the only difference is, pumps are used. In this type of reboiler, liquid from the bottom of the distillation column goes into the pump suction and discharges into the reboiler inlet. Hence pump is used to circulate the distillation bottom liquid into the reboiler bottom and in this way, it is heated and converted in to vapour liquid mixture.
FAQ (What are reboiler and types of reboilers)
1. Why reboiler is used in the distillation column?
Ans – The distillation column is used for separating components or substances and it requies heat. Reboiler are a type of heat exchanger that provides heat to the column bottom liquid and generate vapour.
2. What is the difference between boiler and reboiler?
Ans – Boilers are used to generate steam in for the generation of electricity and reboiler are used to reboil the distillation column bottom liquid using steam or other heating media.
3. What is the difference between kettle reboiler and thermosyphon reboiler?
Ans – In kettle type reboiler, external equipment is used i.e. pump to perform force circulation whereas in thermosyphon reboiler, the thermosiphon effect is used to perform natural circulation.
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