Types of Distillation – Distillation is a unit process widely used operation in chemical industries all over the world to separate components of a mixture. Distillation is a process of liquid evaporation and converted into vapor and recondense and collected in a vessel. In the manufacturing process, distillation is a commonly used unit operation as a part of the solvent recovery process (SR Plant), impurity removal process or purification process, and many more. Today we are going to learn Types of Distillation and the definition of the distillation process.
What is Distillation | Definition of Distillation | What does distillation mean?
Distillation can be defined as the process of separating components or substances from the mixture using different boiling points or relative volatility. In other words, the distillation Process involving the conversion of a liquid into vapor that is subsequently condensed back to liquid form and herby separates one liquid from another. Learn What are unit operation and unit process.
Types of Distillation | Different types of Distillation
- Simple distillation
- Steam Distillation
- Vacuum Distillation
- Fractional Distillation
- Azeotropic Distillation
- Extractive Distillation
Let us have simple introduction to all the different types of Distillation, working principle of distillation process.
1. Simple Distillation
Simple distillation is the basic type of distillation process in which a liquid mixture of two-components is heated until the substance with lower boiling point starts vaporizing. The vapor is then condensed with the help of a condenser with suitable utility and then collected in another vessel. Simple distillation is used to separate the mixture have a wide boiling point difference of more than 25 degrees or more.
2. Steam Distillation
Simple distillation is the basic type of distillation process in which steam is introduced to the mixture which is to heat the liquid mixture which will increase the vapor pressure of the components. When the vapor pressure of the immiscible components outplace the atmospheric pressure, the high boiling component will start evaporating at low temperature and form a mixture with water.
Steam distillation is used to separate out the heat-sensitive components which can decompose at high temperatures. A common example of Steam distillation is it is used to extract oil from plant matter.
3. Vacuum Distillation
The distillation process can be classified as atmospheric distillation and vacuum distillation. The distillation process which is conducted under vacuum or negative pressure is known as vacuum distillation. It is similar to atmospheric distillation but the only difference is vacuum distillation is conducted under vacuum. The boiling point is directly proportional to pressure. If the boiling point of any substance present in the mixture is high, in that case we need to use utility which can help to achieve the boiling point of that high boiling component which will be costly. So to avoid using that utility, vacuum distillation is used in which vacuum is created in the column which will decrease the boiling point of component and hence separation can be achieved at low temperature.
4. Fractional distillation
Fractional Distillation the principle behind fractional distillation is different components in the mixtures boils at different temperatures. In fractional distillation, so the mixture is heated and the low boiling substance starts evaporating first, condenses the liquid first, and separate out. Now increase the temperature and similarly separate out the components from lower boiling point to higher boiling point.
Fractional distillation is carried out commonly in refinery where distillation of crude oil is carried out. Different component like petrol, diesel, kerosene, naptha are seperated from the crude oil using fractional distillation as boling point of these substances present in the cude oil are different.
In mean time, you can also read When vacuum distillation is selected & Purpose of vacuum distillation
5. Azeotropic Distillation
Azeotropic distillation is carried out when we have a mixture of immisible liquid which cannot be seperated using simple distillation as the diffence in boling point is very low and such mixtures are called as azeotropic mixture. If we carried out simple distillation of the azeotropic mixture, vapor generated by heating the mixture will contain both the component, hence seperation though simple distillation method can’t be done. In this case, Azeotropic distillation process is carried out.
In the Azeotropic distillation method, in the mixture of supposing A and B, an additional substance i.e. C is added which has an ability to alter the activity coefficient of the components and herby change the relative volatility of the mixture. The third component added in the mixture is known as entrainer which will create either minimum-boiling with one of the components.
6. Extractive Distillation
Extractive Distillation can be defined as distillation performed in the presence of a miscible, high-boiling, relatively non-volatile component, the solvent, that forms no azeotrope with the other components in the mixture. This method is used for mixtures having a low value of relative volatility, nearing unity. In this method, an additional component called entrainer is added to the mixture but it will not form any azeotrope but act differently with the component of the mixture and cause a change in relative volatility to allows the new three-part mixture to be separated by normal distillation.
This was the simple introduction article on what is Distillation and different types of distillation. we will be covering different types of distillation in detail so stay tuned with us. If you are a chemical engineering student, working professional, or in case you want to have chemical engineering knowledge, check our our blog, we had covered various articles related to chemical engineering and Industrial safety. check out What is P&ID Diagram & Uses – P&ID Diagram basics symbols.