Hydrocarbon dehydration
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In industry, an azeotropic distillation column is commonly used for deep dehydration. For example, if the water content of isobutylene in the feed is 500 PPM and it needs to be reduced to 50 PPM, in industrial processes a portion of the hydrocarbons is vaporized together with the water, cooled, dehydrated in a reflux drum, and then returned to the column to continue the dehydration process. However, when using ASPEN for simulation, it is not possible to separate the water from the hydrocarbons; the water and hydrocarbons do not phase separate in the reflux drum. The property data I used was UNIQUAC, and it was also not possible to find the azeotrope temperature. I wonder how others simulate such distillation columns using ASPEN.
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After dehydration in the reflux tank, it is then sent back to the tower for further dehydration – could you explain this in more detail? What is the dehydration method?
Excuse me, have you figured this problem out? Butane has a heterogeneous azeotrope with water. The water that needs to be separated from butane is dissolved water, that is, trace amounts of water dissolved in butane. In this case, due to the very low water content, the hydrogen bonds between water molecules are broken apart by isobutylene or butane itself; as a result, the boiling point of water is lower than that of isobutylene. Therefore, in such a situation, water acts as a light component and moves to the top of the distillation tower. These are some of the opinions I’ve seen on forums, as I have also been thinking about this issue. As for dehydration through the reflux tank (the question here is why water can be removed after it reaches the top of the tower and enters the reflux tank; shouldn’t the water remain dissolved together with the material? Wouldn’t that mean that the material would be removed along with the water during dehydration?) ) What I’ve seen is that the principle of partial pressure is utilized (that is, Dalton’s law of partial pressures, in other words, bringing the water to its condensation pressure)