Effect of reboiler temperature on the light component content in the reboiler outlet product
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With the feed composition remaining constant, what is the effect of the reboiler temperature on the content of the light components in the reboiler outlet stream? If the light components in the bottom of the tower are above the specified level, should the tank temperature be lowered slightly? What is the reason for this?
To put it the other way around, if the concentration of light components is too high, the temperature of the reactor is increased to vaporize them away.
However, the temperature at the bottom of the tower has now reached the boiling point of the heavy components (the target product). If the temperature at the bottom of the tower is increased further, won’t a large amount of those heavy components be vaporized as well?
To increase the temperature at the bottom of the tower, the light components in the liquid in the tank must first be vaporized!
Your situation indicates the formation of an azeotrope, and ordinary distillation can no longer separate them.
Azeotropes cannot form between light and heavy components. What will happen if the temperature at the bottom of the tower reaches the boiling point of the heavy components?
You can use vacuum distillation to carry out the separation; this not only helps to lower the temperature of the reactor but also allows the light components to be separated! ! ! ! ! ! ! ! ! ! ! !
The function of the reboiler bottom is to increase the concentration of the heavy components; the light components at the bottom of the tower are vaporized by the gaseous reflux continuously provided by the reboiler, thereby removing them from there. The high temperature at the bottom of the tower you mentioned may carry some of the heavier components to the top of the tower, resulting in a decline in the quality of the product at the top. At the same time, the liquid level at the bottom of the tower drops, leading to a reduction in the amount of liquid that can be extracted from there.
To ensure that the light components in the reformed fraction at the bottom of the tower remain within a certain range, the temperature at the bottom of the tower is kept slightly below or equal to the boiling point of the heavy components. It is only at this temperature that the light components can vaporize and rise; reaching the boiling point of the light components alone is not sufficient for them to all ascend!