Patent GB-712311-A (GB)
Title: Device useful for the fractional distillation of liquids
Inventor: BOWDEN CYRIL HENRY
IPC: B01D3/08
Filed: 1950-03-03
Abstract: <PICT:0712311/IV (b)/1> Apparatus for extracting acetic acid from aqueous solution by contacting the solution with benzene comprises a horizontally-disposed cylinder d containing a coaxial slowly rotating shaft e to which a plurality of circular stainless steel discs are attached, wherein alternate discs a extend to the inner periphery of the cylinder and are perforated in the area adjacent to the shaft, and the other discs b are of smaller diameter and non-perforated. The solution of acetic acid, containing for example 5 per cent of the acid, is fed into the vessel through pipe h and, after filling the trough-like portion k, k at the bottom of the vessel, flows out through an outlet (not shown) adjacent to pipe f.  Benzene is fed into the vessel through pipe f and, after filling the remaining space in the vessel, flows out through pipe g.  The discs are preferentially wetted by the benzene so that, as the discs rotate, a film of benzene is carried through the aqueous solution, extracts acetic acid therefrom, and delivers it to the bulk of the benzene phase.ALSO:<PICT:0712311/III/1> Fractional distillation is effected by passing the vapours from a still through an inlet f into one end of a horizontally-disposed cylinder d containing a co-axial, slowly-rotating shaft e to which a plurality of circular discs are attached radially, alternate discs a extending to the inner periphery of the cylinder and being perforated in the area adjacent to the shaft, the other discs b being of smaller diameter and non-perforated; the vapours leaving the opposite end of the cylinder through outlet g, are condensed, and part of the condensate is returned through pipe h to the cylinder where it forms a small volume of reflux-liquid kk in the lowermost part thereof.  The vapours are thereby made to traverse a meandering passage (dotted line zz), and sweep over surfaces which are wet with reflux-liquid.  A spiral groove is preferably cut on surface of each disc, so as to increase the area of wettable surface and to promote turbulence in the vapour-stream. Plates c, in the form of circular segments, are attached to the lower periphery of the cylinder, between each pair of discs.  When the apparatus has been operating for some time, the reflux-liquid passes out of the cylinder through opening f at a rate equal that at which it enters the cylinder through pipe h.  In an example, a cylinder 8" in internal diameter containing 50 discs (25 of each kind) spaced 3/16 " apart, was tested with a mixture of o-xylene and p-xylene at a pressure of 400 mm.  When operated under conditions of total reflux, the discs being rotated at 50 r.p.m., the compositions of the liquid at the two ends corresponded with a separation equivalent to 7.6 transfer units. The apparatus has a much lower pressure-drop than a packed column of equal efficiency; and the area of surface which has to be lagged is much less.  The apparatus is advantageous for fractional distillation at a pressure of 10 mm., or less.  The Provisional Specification states that the discs may be constructed of porous material.