GB694343A - Improvements in or relating to spray driers - Google Patents

Abstract

<PICT:0694343/III/1> A spray evaporator for obtaining stable, freely-flowing powders from solutions and slurries, wherein the solution or slurry is sprayed into the top of the evaporator and contacted therein with hot air, characterized by the provision, in the base of the evaporator, of baffles over which the particles move downwards, and of means for inducing cool air to pass transversely through the down <PICT:0694343/III/2> wardly - moving particles. The drying of soaps, and of wetting agents such as aliphatic sulphates and sulphonates and alkyl aryl sulphonates, is referred to. Also the drying of amino acids, proteins (e.g.eggs), and salts (carbonates and borates). In the evaporator shown in Fig. 1, the solution is sprayed into shell 10 through circularly-arranged nozzles 13, and hot air is introduced through conduit 11. Partially-dried particles and air are discharged into chamber 18 through a hole in the base of frusto-conical section 14. The air changes direction and passes through annular space 16 and ducts 19 to outlet-conduit 12, but the particles travel on downwardly to deflecting wall 23. The particles then pass through opening 22, and flow over a series of annular baffles to conveyer 20. While falling between the baffles, the particles are dried and cooled by air at atmospheric or room temperature flowing transversely through them; the cooling streams being induced by the application of suction at the lower end of pipe 30. Cooling air enters the pipe 30 through openings 32 and through the open upper end 31; turbulence in cone 23 being prevented by four vanes 33 extending from the pipe to the inner wall of the cone. Fig. 3 shows another embodiment of the final drying and cooling system. In this case the particles flow over a series of spaced conical baffles 133, 34, 35, positioned within the outlet of chamber 18; and the cooling air is sucked, through spaces 36, 37 and transversely through the falling particles, into chamber 18 by means of a suction-device attached to conduit 12 (Fig. 1).