In comparison between simple distillation and vacuum distillation, in which one will the water boil more vigorously (large number of bubbles burst during boiling)?
Atmospheric distillation is a technique used to separate components in crude oil that is performed under atmospheric pressure. This technique is used to separate components having a low boiling point (low boiling fractions).
In this process, pre-heated crude oil (heated to about 250-260°C) is further heated to a temperature around 350°C. This heated crude oil is then passed into a distillation column in which the pressure at the top is maintained around 1.2-1.5 atm (nearly the atmospheric pressure).
The feed of the atmospheric distillation is desalted and pre-heated crude oil. The components separated by this distillation method are small hydrocarbons such as fuel gases, naphtha, kerosene, diesel, and fuel oil. The residue left at the bottom of the atmospheric distillation column is known as the heavy hydrocarbon fraction. This fraction is sent to the vacuum distillation.
Vacuum distillation is a technique used to separate components in a mixture at a reduced pressure. This process is used when the components in the mixture have boiling points which are difficult to be achieved or if higher temperature cause the compounds to be decomposed instead of vaporizing. A reduced pressure causes the components to have a low boiling point than usual.
In the industrial scale distillation processes, there are many stages of distillation involved in order the separate key components in a mixture. In situations like this, vacuum distillation is a better option. This technique increases the relative volatility of the components in a mixture (the relative volatility is the difference between boiling points of two components). When the relative volatility is high, a better separation of components can be observed.
In a simple distillation, a homogeneous liquid mixture is boiled. The rising vapor then enters the inner chamber of a water-cooled condenser. The vapor condenses to a liquid, called the distillate, which is then collected in a separate vessel.
A technique used to gently separate compounds from a liquid. By lowering their boiling point with the help of vacuum. This method, called vacuum distillation, is sometimes employed when dealing with substances that normally boil at inconveniently high temperatures or that decompose when boiling under atmospheric pressure
Water boiling depends more on heat input than the column pressure. if you imput more heat you will have more vapour phase in both cases: High pressure and low pressure. As our collegues above said, the use of vaccum or pressure is governed by process conditions.
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