How to make distillation more energy-efficient
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Two-component distillation, but one of the components is present in very small quantities; for example, when recovering ethanol from an 3% ethanol aqueous solution, the flow rate is 5 T/h. Is it done by using one column to directly separate water free of ethanol from 95% ethanol, or is it first done using one column to obtain water free of ethanol and a 50% ethanol aqueous solution, after which another column is used to process this 50% ethanol aqueous solution in order to obtain water free of ethanol and 95% ethanol? Which is more energy-efficient? Or conversely, when treating a 93% ethanol aqueous solution, the flow rate is 5 T/h. Is it done by using one column to directly separate water free of ethanol from 95% ethanol, or is it first done by using one column to obtain 50% ethanol aqueous solutions and 95% ethanol aqueous solutions, and then another column is used to process the 50% ethanol aqueous solutions in order to obtain water free of ethanol and 95% ethanol? Which is more energy-efficient?
Note: All are at atmospheric pressure distillation, with no consideration for heat recovery.
Thank you for the reply. My goal is to explore whether two-stage distillation should be used, and whether the reflux ratio in two-stage distillation can be lower than that in single-stage distillation.
Personally, I think using a single batch is more energy-efficient, but I have no experience with such a low concentration of 3%. Moreover, the greater the difference in boiling points between the two substances, the more energy-efficient using a single batch is.
This post was last edited by CHANGBAISHI on 2021-3-20 09:02. To be honest, I’ll mention something unexpected about the topic; it might be helpful to you. First, for technological upgrades, one must consider the cost of investing in equipment as well as having technical support. Discussions of this kind, which are quite obvious, have little practical value. It is best to respect the operating conditions of existing equipment as well as their design specifications, and to operate them strictly in accordance with the prescribed procedures and conditions – this is the most effective way to save energy and reduce consumption. For reference.
If it’s really such a dilute ethanol solution, sell it to wastewater treatment plants. It can be used as a carbon source.
This requires distillation simulation calculations. First scenario: The second method might be more energy-efficient, that is, to concentrate first and then separate precisely ； In the second case, it still needs to be calculated.
Thank you for your suggestion; I plan to find a colleague to simulate it with.
It depends on the specific material; you need to specify this component clearly
First, ethanol in the water is recovered to obtain an ethanol mixture with a higher concentration, which is then distilled to produce 95% ethanol. Start with the easy tasks and handle the difficult ones in small amounts. It is based on the phase diagram.