GB1281047A - Irradiation apparatus - Google Patents

Abstract

1281047 Irradiation apparatus SULZER BROS Ltd 29 Sept 1969 [10 Oct 1968] 47689/69 Heading H5R Apparatus for irradiating granular materials such as cereals includes a through-flow vessel 1 having feeder and discharge arrangements for controlling the rate of flow of the material, and a pattern 3 of irradiation members extending at right angles to the flow path and over the entire cross-section of the vessel, the members being arranged such that radiation is emitted along the flow path. The irradiation members may be cobalt 60 elements contained in tubes 6 mounted in a pair of facing walls of the vessel, through which the elements may be withdrawn, the tubes-which may be staggered in the vertical direction to minimize flow restriction-having inclined covers 7 to prevent retention of material thereon. The feeding apparatus 10 is controlled by a level gauge 43 to maintain a constant height of material in the vessel, while the discharge rate is controlled by the speed of rotation of the knife cylinders 24, 25, 26, and 27. To compensate for reduced irradiation intensity adjacent the walls of the vessel, the discharge rate is reduced, adjacent the pair of walls in which the cylinders are mounted, by reducing the volume of the pockets defined by adjacent knives with annular blocks which are axially tapered towards the mid-points of the cylinders (Fig. 2a and 2b, not shown) and, adjacent the other pair of opposite walls, either by the use there of cylinders of increased diameter to reduce the pocket volume (Figs. 3a and 3b, not shown), or by an increased spacing between the cylinders adjacent the walls (Figs. 4a and 4b, not shown). In other arrangements, the knives of those cylinders nearest the vessel wall may be of reduced radius, or those cylinders may be rotated at reduced speeds. Uniformity of irradiation over the cross-section of the vessel may be further improved, Fig. 5, by varying the distribution density of the irradiating elements in the pattern 3, by reducing both the spacing between the tubes 6, and the spacing within the tubes of the elements 85... 88, adjacent the walls of the vessel. In a modified apparatus (Fig. 6, not shown) the feeder arrangement 10 is replaced by a periodically fed hopper (101) forming a buffer volume upstream of the vessel 1, a screening member (103) mounted immediately beneath the region of restricted cross-section joining the hopper to the vessel preventing premature irradiation of the material.