GB769228A - Improvements in and relating to apparatus for distillation and chemical reaction and the use thereof - Google Patents

Abstract

Apparatus, which permits the rapid establishment of equilibrium between liquid and vapour phases such as is required in fractional distillation and in certain chemical reactions, comprises a column which is provided with external heating and/or cooling means and has disposed, along its inner wall, a helical gutter which to a large extent is open to the interior of the column but is closed <PICT:0769228/III/1> <PICT:0769228/III/2> at one or more levels by axial strips, and is also provided with a central rotatable shaft on which is mounted a hollow screw conveyer, both of which may be perforated, with connections for passing liquids, vapours or gases into the conveyer and shaft, means for introducing liquid, vapour or gas into the column at chosen levels, means for discharging liquid from the column, and a vapour or gas exhaust at the top of the column. The apparatus shown is suitable for the preparation of sulphuric acid. A rotatable column 1 is provided with a helical gutter 2, and is divided into four sections I to IV. In section II the gutter is separated from the central part of the column by strip 3. A hollow shaft, divided into two parts by dam 24, extends through the column. Sections I and II are cooled by water discharged from orifices 17. Sections III and IV are heated by the hot gases obtained by roasting the sulphurous raw material, which are led into jacket 30 at inlet 29 and removed through outlet 31; the gases then enter the bottom of the column through inlet 32. The formation of sulphuric acid from sulphur dioxide, oxygen and water, under the catalytic influence of nitrous vapours, takes place in the central part of section II of the column. The water required is partly formed by condensation of steam ascending from section IV, and partly comprises cooling water supplied through line 13 and discharged into section II through orifices 21. In section I the nitrous vapours, which are present in the gases ascending the column, are absorbed in 70 per cent sulphuric acid, which is supplied through line 19 and flung from the rotating shaft against the inner wall of the column through orifices 20. The nitrose obtained moves downwardly along gutter 2 into section III. The sulphuric acid formed in section II flows down into section III on the opposite side of strip 3 to the nitrose. In section III, the acid and nitrose are mixed and heated whereby the nitrous vapours are expelled. The acid is finally concentrated in section IV by steam introduced through line 26 and orifices 27. The acid is then flung from the column through orifice 33, and leaves the apparatus through line 34. Nitric acid, for compensating nitrogen-losses, is supplied by line 22 and orifices 23 into section III. The process may be carried out under pressure. When used for cracking hydrocarbons, the lower part of the column is made of, or coated with, a catalytic material, which may be heated to produce a temperature gradient which rises from the bottom. In the embodiment suitable for fractional distillation, the conveyer is not perforated, and cooling liquid (for dephlegmation) is circulated through it.