In distillation there are lots of important which might affect process's efficiency, operating cost and capital cost. One of them is reflux ratio. This ratio is already defined in a certain way.
Below is the picture of the upper part of the column ( column section above the feed ):
Reflux ratio is defined like this:
v = liquid which is going back to the column, R / liquid which is taken out, D
Normally the reflux ratio is 1.5 to 2 times bigger than the minimum reflux ratio.
It is worth mentioning that if reflux ratio is too low, it is bad and if it is too high, it is also problematic. Below is the graph that can explain why the right range of reflux ratio's value is crucial:
Theoretically high reflux ratio is good to obtain a pure top product. However high reflux ratio also means high operating cost. More liquid remains in the column therefore more energy is needed to reboil it.
If it is too low, capital cost increases significantly. This is because more stages are needed to obtain the same product's quality. Minimum reflux ratio means the number of stages that we need is infinite. In practice we want to avoid a situation with high number of stages and high energy consumption.
Below is the picture of the upper part of the column ( column section above the feed ):
Reflux ratio is defined like this:
v = liquid which is going back to the column, R / liquid which is taken out, D
Normally the reflux ratio is 1.5 to 2 times bigger than the minimum reflux ratio.
It is worth mentioning that if reflux ratio is too low, it is bad and if it is too high, it is also problematic. Below is the graph that can explain why the right range of reflux ratio's value is crucial:
Theoretically high reflux ratio is good to obtain a pure top product. However high reflux ratio also means high operating cost. More liquid remains in the column therefore more energy is needed to reboil it.
If it is too low, capital cost increases significantly. This is because more stages are needed to obtain the same product's quality. Minimum reflux ratio means the number of stages that we need is infinite. In practice we want to avoid a situation with high number of stages and high energy consumption.
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