Seeking help with a distillation column design problem
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This post was last edited by Medidou2 on 2017-8-11 at 10:32. Topic: Design a methanol distillation column fed with 50 kmol/h of methanol and 50 kmol/h of water; with a reflux ratio of 1.5, the purity of both the top and bottom products is required to be 99.5%. Determine the number of theoretical plates in the distillation column, the feed position, as well as the temperature, gas and liquid flow rates, and composition distributions within the column. Through precise calculations, I found that when the reflux ratio is 1.5, the purity at both the top and bottom of the tower is only 93.4%; whereas to achieve a purity level of 99.5%, the reflux ratio needs to be around 2.x (I can’t remember exactly, but it’s definitely not 1.5). How should the system be designed to meet the requirements specified? The attachment is something I simulated on my own; I seek guidance
Are the number of plates and the top product yield consistent with those in the example?
What do you mean? The problem only provides these conditions; I assumed the pressures of the condenser and the reboiler myself. What are you trying to say?
As for the specific procedure, the feeding position was first set through a simplified calculation, and then determined through a more precise calculation
As for the specific procedure, the feeding position was first set through a simplified calculation, and then determined through a more precise calculation
Conduct sensitivity analysis to ensure that the results meet the separation requirements, and then determine the feed position
After determining the feed position, define the design specifications and then proceed with operation
My point is that if you want to obtain the same results as in the example, then the design parameters of the tower (number of theoretical plates, efficiency, feed position, type of condenser/reboiler), as well as the operating parameters (recovery ratio, heat load, amount taken from the top of the tower, etc.), must be identical to those in the example. Otherwise, for an exactly identical separation task, an infinite number of column designs and operating parameters that meet the separation requirements can be obtained.
This is a Dao Lian* type problem for which there are no answers. The attachment I’ve created is based on simplified calculation methods, but it does not achieve the level of purity required by the problem
The number of plates is too low; increase the number of plates