Patent GB-877942-A (GB)
Title: Vaporization by molten material
IPC: F22B1/16
Filed: 1958-12-18
Abstract: <PICT:0877942/III/1> <PICT:0877942/III/2> A process for vaporising a liquid from a less volatile component of a feed mixture comprises contacting the mixture with a molten material, which is less volatile than the liquid to be vaporised, under such conditions that a substantial proportion of the liquid is vaporised and a part of the molten material is solidified, withdrawing the vapour and the unvaporised residue of the feed mixture, and circulating the partly solidified molten material through a heating zone in which the solidified portion is re-melted, the molten material being then recycled to the vaporisation zone.  The heating of the partly solidified molten material may be effected by heat-exchange with the vapours withdrawn from the vaporisation zone, after they have been further heated by compression, and such heat-exchange may be direct or in direct.  Fig. 1 shows an apparatus in which the molten material is lighter than the feed mixture and the re-melting of the partly solidified molten material is effected by direct contact with the vaporised part of the mixture, after compression.  Molten material is supplied to a vaporising vessel 1 through a pipe 3 and the feed mixture is supplied through a pipe 4.  The molten material fills the vessel between the levels UL and LL and the unvaporised residue of the feed mixture accumulates in the bottom of the vessel, whence it is withdrawn by a pipe 7.  The vaporised part of the mixture passes via pipe 5 to a compression pump 6, whence it is passed by pipe 10 into direct contact in the vessel 2 with the slurry of molten and solidified material which is withdrawn from the vessel 1 by pipe 8 and returned, after re-melting, by the pipe 11.  The condensed vapours are withdrawn through pipe 13.  A modified apparatus is described (Fig. 2, not shown) in which the compressed vapours pass through a coil in the partly solidified molten material and in which the separate vessels, 1, 2 are replaced by a single vessel having a central vertical baffle.  Fig. 3 shows an apparatus in which the molten material is heavier than the feed mixture, the apparatus comprising a vessel 33 divided by a baffle 36 into a vaporising compartment 34 and a condensing and re-melting compartment 35. The feed mixture is supplied by pipe 37 and rises through the molten material, which fills the compartment 34 up to the level LL.  The unvaporised part of the mixture accumulates above the molten material between the levels LL and UL, and is withdrawn by pipe 40.  The vapours pass to compression pump 39 and thence through pipe 41 into contact with partly solidified molten material in compartment 35, the molten material being drawn into the compartment through the pipe 43 by the suction created by the passage of the vapours through the pipe 41.  Condensate collects in compartment 35 between the levels LL and UL and is withdrawn through pipe 42.  The vapours from the compartment 34 may alternatively be passed by pipe 63 to a fractionator 44, from which condensate is withdrawn by pipe 46 and vapours pass by pipe 45 to the pump 39.  Also, steam or a gas may be introduced into compartment 34 by pipe 47, to assist vaporisation.  A modified apparatus is also described (Fig. 4, not shown) in which the heat-exchange between the compressed vapours and the partly solidified molten material is indirect and in which the molten material is caused to circulate around a central vertical baffle by supplying the feed mixtures through a suitably located jet.  In this modification also the feed mixture is warmed by heat-exchange with the condensate.  The process is particularly applicable to the production of demineralised water from sea-water and other aqueous salt solutions, and in this application the molten material may be a wax, e.g. paraffin wax, naphthalene, an alloy, e.g.  Wood's metal or Rose's metal, sulphur, or a halogenated or alkylated aromatic hydrocarbon melting in the range 120-480 DEG F. Examples of the treatment of sea-water are given, and reference is made also to the evaporation of water and glycerine from spent soap lyes and to the separation of components of organic mixtures.