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[gaemon]

Good day to all of you experienced senior engineers,

I am a university student. I am doing vacuum distillation column design to separate components including methyl esters (C14-C18:2), triglycerides (C14-C18:2), methanol, water, and glycerol for palm methyl ester production. My assumptions include 99.5% methanol is in distillate, 95% water in bottom, and glycerol purity is 82%. Vacuum condition (25kPa) is set to prevent the decomposition of glycerol (a valuable by-product from transesterification reaction).

Based on my limited knowledge, tower packings (either random or structured) are more suitable for vacuum column as they inherently produce lower pressure drop than fractionating trays. The other day, my supervisor asked me to look into the possibility of applying combined packed and tray in the column for increased efficiency.

I have been looking for references both online and offline but up until now there is very little information concerning this type of arrangement. I am confused by several reasons:

i) How the setup will be whether trays are positioned at rectifying section and packed column at stripping section or vice versa.
ii) How will this affect the entire calculation in determining column specs (e.g. height, diameter, etc)
ii) Are there concrete justifications for this?

I will gladly provide further information for your convenience later.

Thank you very much,

Ahmad.