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Difference between revisions of "Distillation"
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==Feedstock== | ==Feedstock== | ||
=== Origin and composition === | === Origin and composition === | ||
Since distillation is limited for the use of liquid mixtures, the feedstock needs to be in liquid form. Examples in the field of [[biowaste]] here are fermented biowaste resources | Since distillation is limited for the use of liquid mixtures, the feedstock needs to be in liquid form. Examples in the field of [[biowaste]] here are fermented biowaste resources, as bioethanol, or bio oils. <ref name=":0">{{Cite journal|title=Techno-economic assessment of hybrid extraction and distillation processes for furfural production from lignocellulosic biomass|year=2017-12|author=Le Cao Nhien, Nguyen Van Duc Long, Sangyong Kim, Moonyong Lee|journal=Biotechnology for Biofuels|volume=10|issue=1|page=81|doi=10.1186/s13068-017-0767-3}}</ref><ref name=":1">{{Cite journal|title=Renewable diesel blendstocks produced by hydrothermal liquefaction of wet biowaste|year=2018-11|author=Wan-Ting Chen, Yuanhui Zhang, Timothy H. Lee, Zhenwei Wu, Buchun Si, Chia-Fon F. Lee|journal=Nature Sustainability|volume=1|issue=11|page=702–710|doi=10.1038/s41893-018-0172-3}}</ref> | ||
=== Pre-treatment === | === Pre-treatment === | ||
For a distillation no specific pre-treatment is needed since it is used to separate different fraction within a process chain. To gain a liquid product from bio waste resources, [[fermentation]] or [[hydrothermal processing]] (hydrothermal liquefaction) are possible pre-treatment technologies. Sometimes there are combination options with other technologies, such as [[extraction]] or [[esterification]], for higher efficiencies.<ref name=":0" /><ref name=":1" /> | For a distillation no specific pre-treatment is needed since it is used to separate different fraction within a process chain. To gain a liquid product from bio waste resources, [[fermentation]] or [[hydrothermal processing]] (hydrothermal liquefaction) are possible pre-treatment technologies. | ||
Sometimes there are combination options with other technologies, such as [[extraction]] or [[esterification]], for higher efficiencies.<ref name=":0" /><ref name=":1" /> | |||
==Process and technologies== | ==Process and technologies== | ||
[[File:Total Reflux.png|thumb| | [[File:Total Reflux.png|thumb|266x266px|Distillation column]][[File:Colonne distillazione.jpg|thumb|Typical industrial distillation towers|237x237px]] | ||
Distillation exploits differences in ''relative volatilities'' of the feed mixture components. In a distillation column a feed stream enters in the middle of the column and two streams leave, one at the top and one at the bottom. Components with ''lower boiling points'' are concentrated in the stream leaving the top while components with ''higher boiling points'' are concentrated in the stream leaving the bottom. | Distillation exploits differences in ''relative volatilities'' of the feed mixture components. In a distillation column a feed stream enters in the middle of the column and two streams leave, one at the top and one at the bottom. Components with ''lower boiling points'' are concentrated in the stream leaving the top while components with ''higher boiling points'' are concentrated in the stream leaving the bottom. | ||
Separation is achieved by controlling the column temperature and pressure profiles to take advantage of differences in the relative volatility of the mixture components and therefore tendency to change phase. The lighter, lower boiling point components evaporate to the top of the column and the heavier, higher boiling point components condense to the bottom of the column. | Separation is achieved by controlling the column temperature and pressure profiles to take advantage of differences in the relative volatility of the mixture components and therefore tendency to change phase. The lighter, lower boiling point components evaporate to the top of the column and the heavier, higher boiling point components condense to the bottom of the column. | ||
This application is often referred to as ''rectification'', which is a successive distillation. A simple distillation is not often used for industrial applications. | This application is often referred to as ''rectification'', which is a successive distillation. A simple distillation, as it can be seen below, is not often used for industrial applications. In simple distillation, the vapor is immediately channeled into a condenser. As a result, simple distillation is effective only when the liquid boiling points differ greatly or when separating liquids from non-volatile solids or oils. For these cases, the vapor pressures of the components are usually different enough that the distillate may be sufficiently pure for its intended purpose. | ||
[[File:Distillation Apparatus.jpg|center|thumb|Simple distillation apparatus]] | |||
The main advantages of rectification are that the system can be operated continuously and that the separation effect is many times greater than that of a simple distillation. The reason for this lies in the several countercurrent contacts of the vapour with the liquid. Therefore, rectification is preferred to sequential single distillations. | |||
A plant that performs distillation is called a ''distillery''. The apparatus used to perform distillation is called a ''still''. | |||
==Products== | ==Products== | ||
With distillation two products are obtained. The product leaving the column at the top is referred to as distillate, while the product leaving at the bottom is referred to as bottom product or shortly bottoms. | With distillation two products are obtained. The product leaving the column at the top is referred to as [[distillate]], while the product leaving at the bottom is referred to as bottom product or shortly bottoms. | ||
=== Post-treatment === | === Post-treatment === | ||
The post-treatment of the products | The post-treatment of the products depend on the next steps within the production chain. With distillation, it is not possible to completely purify a mixture of components, as this would require each component in the mixture to have a zero partial pressure. If ultra-pure products are the goal, then further [[chemical separation]] must be applied. | ||
==Technology providers== | ==Technology providers== | ||