Heuristic rule is a set of rules that can be used in order to solve problems which might occur in distillation fields. It also helps in terms of running distillation efficiently and optimising the process.
This is taken from those people who worked in the industry or are now working there. In other words these rules are based on experience. By applying these rules we can rule out those process which are not promising.
These are examples of those rules. There are a lot of them. However in the post i would like to highlight only five of them.
1) Remove thermally unstable, corrosive, or chemically reactive components early in the sequence.
This is just to avoid or lower the risk. The risk of something unwanted to happen is higher if it is not removed at the beginning of the sequence.
2) Remove final products one by one as distillates.
The final product must be drawn from the top of the column and not at the bottom. This is due to the fact that the product might get contaminated if it is taken out from the bottom of the column because of the wall corrosion for example.
3) Sequence separation points to remove, early in the sequence, those components of greatest molar percentage in the feed.
By removing those components with the higher amount from the column, there is no need to use a bigger or thicker column for the next separation. The bigger the column is, the higher is the capital cost.
4) Do the separation points in the order of decreasing relative volatility.
The split of components with higher relative volatility is done first. The easiest split is to dealt first.
5) Sequence separation points that favour near equimolar amounts of distillate and bottoms in each column.
This means:
if we have 0,3 mol A, 0,3 mol B and 0,2 mol C, 0,15 mol D and 0,05 mol E, we split A and B first as the amount of A and B is the same. Hence it favors the equimolar split.
It is however worth mentioning that not all of them can be fulfilled at the same time. Sometimes only some of them are important and the rest is not.
This is taken from those people who worked in the industry or are now working there. In other words these rules are based on experience. By applying these rules we can rule out those process which are not promising.
These are examples of those rules. There are a lot of them. However in the post i would like to highlight only five of them.
1) Remove thermally unstable, corrosive, or chemically reactive components early in the sequence.
This is just to avoid or lower the risk. The risk of something unwanted to happen is higher if it is not removed at the beginning of the sequence.
2) Remove final products one by one as distillates.
The final product must be drawn from the top of the column and not at the bottom. This is due to the fact that the product might get contaminated if it is taken out from the bottom of the column because of the wall corrosion for example.
3) Sequence separation points to remove, early in the sequence, those components of greatest molar percentage in the feed.
By removing those components with the higher amount from the column, there is no need to use a bigger or thicker column for the next separation. The bigger the column is, the higher is the capital cost.
4) Do the separation points in the order of decreasing relative volatility.
The split of components with higher relative volatility is done first. The easiest split is to dealt first.
5) Sequence separation points that favour near equimolar amounts of distillate and bottoms in each column.
This means:
if we have 0,3 mol A, 0,3 mol B and 0,2 mol C, 0,15 mol D and 0,05 mol E, we split A and B first as the amount of A and B is the same. Hence it favors the equimolar split.
It is however worth mentioning that not all of them can be fulfilled at the same time. Sometimes only some of them are important and the rest is not.
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