Distillation problem
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Today, I conducted a series of multi-component distillation experiments. All components were recovered; those with low boiling points had been distilled off by now. The temperature at the bottom kept rising, while the temperature at the top remained unchanged, and no more distillation occurred. I felt that the distillation wasn’t thorough enough, so I steamed it for another half hour, but the situation remained the same. I think it’s possible that as the steam rose, poor insulation caused it to condense in the middle of the distillation column; yet the temperature at the top didn’t change. What could be the reason? Could some expert please provide an answer?
“The temperature at the bottom keeps rising; as the material dries out, the furnace continues to burn, and thus the temperature of the furnace naturally keeps increasing. A small amount of material fails to reach the top; due to insufficient insulation, it condenses in the middle section
I thought the same thing, but the top temperature remains constant, which is confusing. If steam condenses in the middle, the top temperature should decrease, yet it stays the same; I don’t understand why
Insulation will not be the main reason; another reason is that the rising steam of the remaining material lacks driving force.
Is there a liquid level at the bottom? It can be seen when it runs out, right? It’s not at the top of the tower, nor at the bottom; then it must be on the tray
The light component has evaporated completely. The reconstituted fraction does not reach the top of the tower. The components at the top of the tower are in an equilibrium state.
The most likely explanation is that the low temperature is not high enough to reach the boiling point of the heavier components. When multiple components are present at the bottom of the tower, the lower-boiling components are continuously distilled out as the temperature rises. The temperature at the bottom of the tower does not increase very rapidly during the distillation of a particular component; once that component has been distilled out, the temperature rises quickly. It then rises slowly until it reaches around the boiling point of the next heavier component, and this process continues until the last component is distilled. In the situation described by the original poster, there are still components at the bottom – although the temperature may have reached their boiling point, pressure factors, as well as the number of trays and the reflux rate, also need to be taken into account. In my opinion, the temperature at the bottom of the tower is not high enough to reach the boiling point of the heavier components; since these components are not distilled, they do not vaporize either, and therefore the temperature cannot rise to the top of the tower, remaining instead at the bottom.
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:Well, is there any need to think about it? It’s definitely because your evaporation rate is insufficient. An insufficient evaporation rate is caused by a low liquid level, a high boiling point of the heavy components, or too small a temperature difference with the heat source, which prevents large-scale evaporation
The boiling points of the light and heavy fractions differ by too much; is there coking at the bottom of the dry pot?