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[plant king]

we are having an azeotropic distillation column ( lights column ) ,


The lights' column is designed to remove water and the light components (mainly 2-3 Dichloropropene) from the raw Epichlorohydrin stream. Epichlorohydrin forms with water an heterogeneous azeotrope at 760 mm Hg boiling at 88 Deg C having a molar concentration of 63.1 % water and 36.9 % ECH. Also 2-3 Dichloropropene forms with water a heterogeneous azeotrope at 760 mm Hg boiling at 77 Degree C having a molar concentration of 42.6 % water and 57.4 % 2-3 Dichloropropene. The separation of water is aided by recycling in the feed as entrainer a fraction of the Dichloropropenes separated at overhead in way to approach the azeotropic concentrations. The above performances are achieved in a column having 26 theoretical trays (30 + packing section - actual) with an external reflux ratio of about 16 and internal reflux ratio of about 19. In the computation of the reflux ratio the overhead product has to be considered as the sum of water, the light ends and the recycle Dichloropropene entrainer.

design spec :

epichlorohydrin in the overhead stream , as % of epi in feed 0.3 to 0.5
lights concentration at bottoms 3000 ppm normal
6000 ppm max

the above performances are achieved in a loumn having 26 theoretical trys ( 8 above the feed and 18 below the feed ) with an external reflux ratio of about 16 corresponding to an internal reflux ratio of about 19 . the 8 theoretical stages above the feed are made of packing is for corrosion resistance purpose .

can anyone tell me appropriate calculations for reduction of epi in overhead slippage ( it comes to 40 % ) these days .