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Distillation processes are well known and important in various industries for the purification of liquid products. It is a process in which the latent heat of vaporization is used to evaporate any substance in an evaporator chamber, and then condensation takes place to obtain the pure substance. It is used to separate the elements of a solution; however, the elements of the solution may be evaporated at different temperature and pressures. The more volatile substance will evaporate first, and thereby, it can be condensed and separated out.
Different distillation processes are used for different purposes. Some important industries that require distillation, and the required processes of distillation for them, are described below.
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Distillation Method for Botanical Oils
- Steam distillation is the most common method for extracting essential oils. The oil extracted by this method is comparatively better than other newer methods.
- This method is done in a still. Fresh and dry botanical material is put in the plant chamber present inside the still.
- A separate chamber is used to generate steam, and this steam is then pressurized and circulated through the material.
- The temperature of steam is maintained in such a way so as it can open the tiny intercellular pockets of the material. However, it does not exceed the peak point, at which the plant is destroyed or the oil becomes singed or burned.
- The main byproduct of this distillation method is floral water, which is used for skin care.
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Distillation Method for Extraction of Petroleum Elements
- For the distillation of crude oil, industrial distillation is used.
- Industrial distillation involves a number of different distillation processes that take place continuously.
- This method is also used for petrochemical and chemical plants, and natural gas processing.
- This process is used for separating the products of such materials in which every product of the material has a different boiling point.
- The entire process is performed in large vertical cylindrical columns known as Distillation Towers.
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Distillation of Seawater
In this method, the seawater is evaporated in an evaporator chamber, and the heat of this vapor is then used in the second chamber, in which the seawater is already present. The process goes chamber-through-chamber a number of times. This facilitates low losses of energy. The condensation of vapor occurs in each chamber, and the pure water is collected from each chamber.
In this process, first of all seawater is heated below its boiling point. Then the preheated water is passed through another chamber in which it is subjected to decrease the pressure below its vapor pressure, and thereby the water starts boiling. Now, the vapor generated is condensed to get pure water.
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Distillation of Waste Water
- To reduce the wastage of used water in various industries, vacuum distillation is used.
- This method can be used for heavy metal waste water, plating rinse waste water, and wash water.
- The distillation of waste water is important to recover heavy metals and other required elements present in the waste water.
- In the process of vacuum distillation, waste water is collected in a holding tank, and then it is transferred to an evaporator in which distillation takes place.
- Vacuum distillation is also used to distill various materials that can boil at very high temperature (by restricting their decomposition at atmospheric pressure).
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Distillation of Wine, Beer, and Other Alcoholic Products
- Wine and most of the alcohol products involve mainly alcohol and water. It’s important to maintain the percentage of alcohol in it. Due to this fractional distillation is used.
- In this process both the liquids are evaporated from the boiling solution. The boiling temperature of ethanol and water is 79°C and 100°C, respectively.
- The volumes of the solution are needed to collect throughout the distillation. These measurements are also known as fractions.
- The percent composition of both the element is determined by their densities.
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You can learn more about the flash distillation of seawater into potable water for communities or use aboard ships at Bright Hub. Please see "Water Desalination Using Multi-stage Flash Distillation (DSF)" and "What is Multi-Stage Flash Distillation." If interested in home distillation of alcohol for blended motor fuel use, please see "Small Scale Distillation of Ethanol."