What is the difference between vacuum distillation range and atmospheric distillation range?
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Ask for advice: Heavy crude oil is generally subjected to vacuum distillation, so what is the difference between vacuum distillation and atmospheric distillation? How are the data compared and contrasted? Thanks!
Atmospheric pressure distillation is a process of cutting crude oil into different distillates under normal pressure according to the different boiling points of each component in the crude oil.； Nowadays, vacuum distillation is carried out in a vacuum state. As the negative pressure increases, the boiling point continues to decrease, and the slag continuously vaporizes and separates into wax oil components and lubricating oil components.
The normal pressure distillation range and vacuum distillation range mentioned here should be the names under laboratory conditions. Take 300ml of crude oil as the normal pressure distillation range and analyze the yield.； Then take 100ml of the normal residue after fractionation at normal pressure to make the residual distillate (wax oil residual distillation) that is steamed to 340 degrees Celsius under 20mmhg vacuum conditions.
What is the corresponding relationship between vacuum distillation range and atmospheric distillation range? For example, if the vacuum distillation range is 300°C and 30% is distilled, how much can be distilled under normal pressure distillation range? Is there a linear relationship?
The conversion of the reduced pressure Engler's distillation range into the atmospheric pressure Engler's distillation range requires the help of relevant charts or calculation formulas, and is not a simple linear relationship. Generally speaking, the reduced pressure Engler curve is first converted into a reduced pressure TBP curve, then the reduced pressure TBP is converted into a normal pressure TBP, and then the normal pressure TBP is converted into a normal pressure Engler distillation curve. There is a more detailed introduction in "Petroleum Refining Engineering", you can check it out.
You can refer to the distillation analysis methods of D86 and D1160, which have conversions.
The purpose of vacuum distillation is to prevent oil cracking from affecting the experimental results under high temperature conditions.
Generally speaking, to convert the decompression process D1160 under 1mmHg into the D86 process under 760mmHg, you need to first convert the D1160 process under 1mmHg column into TBP under 1mmHg column, then convert the TBP under 1mmHg column into TBP under 760mmHg column, and finally convert the TBP under 760mmHg column into D86 under 760mmHg. Generally speaking, if the temperature exceeds 400℃, D86 is not needed, and D1160 is used to analyze the data. Detailed conversion information can be found in "Crude Oil Distillation Process and Engineering" or "Petroleum Refining Engineering"