GB1135635A - Improvements in or relating to apparatus for forming crystals - Google Patents

Abstract

1,135,635. Crystallizing apparatus; vacuum pans. MASCHINENFABRIK BUCKAU. R. WOLF A.G. March 11,1966 [March 11,1965], No.10934/66. Heading C6B. [Also in DivisionB1] Apparatus, Fig. 1, for forming crystals of a solute, such as sugar, in a supersaturated aqueous solution thereof comprises a heating chamber 3 arranged around a tube 7, and a propeller 12 carrying inclined blades 14, which are accommodated in an annular channel 18 between the upwardly and convergingly tapering, frustoconical upper surface of the propeller's boss 13 and a similar portion 9 within the lower part of the tube 7. The inlet 19 and outlet 20 of the channel 18 have substantially equal cross-sectional areas. The rotating propeller 12 circulates the solution or massecuite in the directions indicated by the arrows. The apparatus may be in the form of a vacuum pan, in which an aqueous solution of sugar is boiled and concentrated, by evaporation of water, until it becomes a massecuite. The pan has a body 1 with a funnel-shaped base 2 leading to a valve 28, through which massecuite can be discharged, and has a heating chamber 3 in the form of a calandria around said tube 7. The calandria comprises upper and lower walls 4 and 5, and a plurality of tubes 6, through which solution or massecuite can circulate. Steam is passed through the calandria. A tubular insert 8 is located within the tube 7. This insert 8 is preferably sealed to the tube 7, as shown, to enclose heat-insulating air in a space 27. The lower part of the insert 8 constitutes said portion 9. Above this portion, the insert divergingly tapers towards the upper wall 4, and may project thereabove, with increased diverging taper, to provide a flared extension 11. The lower edge 10 of the portion 9 may be below the wall 5, as shown, or flush with said wall. The propeller 12 is secured to the lower end of a shaft 15 rotatably mounted in a bearing block 16, supported by arms 17 within the insert 8. The arms 17 are preferably vane-shaped and inclined, so as to impart, to the solution or massecuite, a rotational movement opposite to that of thepropeller. Preferably the number of blades 14 and the number of arms 17 have no common integral divisor. A cavity 21 may be formed in the underside of the boss 13, and a plurality of rectilinear or curved ribs 23 may be carried on the inner wall 22 of this cavity, in staggered relationship with the blades 14, Fig. 3. The boss 13 may be pierced by holes or slots 24. Sugar solution is fed into the pan through a tube having a flared inner end 26, which may extend into the cavity 21, as shown in Fig.1.