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Why would the distillation column stop working well?

Q: We recently installed a liquid seal loot in the outlet take line off of one distillation column in order to increase the take-off rate. Initially, this worked and knocked hours off the distillation time. However, after about four runs its benefits disappeared. Do you know why?

A:

I don’t know what liquid seal “loot” is.  Does you mean liquid seal U-shaped loop that is used to seal a column operating under vacuum?  Given the fact that the column worked well immediately after the installation work and then performance declined suggests to me that fouling may be the problem leading to plugging of the product line over time and that the cleanout before work in the column could be done cleaned out the fouling material. 

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