GB844922A - Improvements in and relating to heat transfer operations and equipment for these purposes - Google Patents

Abstract

<PICT:0844922/III/1> In the evaporation or distillation of liquids or the heating of free-flowing solids wherein the fluid material to be treated is supplied to the interior of a rotor a having a heattransmission surface n, which may be made of corrugated copper-sheet, surrounded by an insulated shell q to which gaseous heating medium is supplied through pipe p, the outside of the rotor is provided with ribs, fins or blades z, which may be perforated to maintain turbulence in the heating medium and to reinforce the heat transmission surface n. The apparatus may also be used as a cooler in the preparation of fluosilicic acid solution and suspended silica by introducing gaseous silicon tetrafluoride and water through pipe p, and supplying cooling-water via pipe g. The apparatus may be used for heating free-flowing raw sulphur ore in order to sublime the sulphur, and for the recovery of the free sulphuric acid from ferrous sulphate pickle liquors. Waste gases and vapours from industrial plant, such as boilers, furnaces, cement kilns and diesel engines, may be used as heating medium. Dust and condensate (from steam) in the heating medium are projected away from the rotor, and the dust is washed down the inside of shell q by the condensate. Both are collected in annular cavity r, and are removed through pipe s. Exhaust gases are withdrawn through pipes C and D. Recompressed vapours may also be used as heating medium. In the case of the vaporization of a liquid, it is supplied through pipe g, from which it drops on to the rotating annular element i so that it is flung centrifugally towards the hot surface n. The liquid forms a column of ring-shaped cross-section, which is considerably thicker than a film, against the surface n. The interior of the rotor is evacuated by means of pipe e. The vaporization takes place without foaming. The vapours, which are generated, pass through perforations u (whereby entrainment is eliminated), and are then withdrawn through pipe e. Concentrated liquid flows continuously from the interior of the rotor into lower channels v1-v8 and also into upper channels w1-w4; and the rotation of the rotor is adjusted so that the interior of the rotor is sealed from the stationary withdrawal channels x and y by the liquid in rotating channels v and w. Solids suspended in the concentrated liquid accumulate in the upper part of the liquid column, and are withdrawn through channels w. Perforated nozzles A and B are fitted to the channels v and w; and the proportion of p liquid removed through the upper and lower channel systems can be adjusted by varying the number and size of the perforations in the individual nozzles. The method may be used for the distillation of sea-water; part of which is introduced into the rotor through pipe g and another part is fed as a film over the inside of the shell j, while combustion gases from a diesel engine are blown in through pipe p. The method may also be used for the concentration of sulphite liquor, or the concentration of sugar and fruit juices. In the latter case, the rotor is made of silver. When corrosive liquids are treated, the rotor may be made of nickel/molybdenum alloy.