Patent GB-1301783-A (GB)
IPC: C01B32/55
Filed: 1971-04-19
Abstract: 1301783 Extruding carbon dioxide AIRCO Inc 19 April 1971 [11 Feb 1970] 21544/71 Heading B5A [Also in Division F4] Carbon dioxide snow 23, is formed into cylindrical pellets 60 upon extrusion, through cylindrical radially directed bores 52, 54 of a stationary die ring 44, by rotary elements 46 and 48 which are mounted for planetary motion within the ring 44 at diametrically opposed positions upon a carrier 40, keyed to a rotated shaft 18. In the Figures 1 and 2 embodiment, the bores 52, 54, provided with conical entries 52<SP>1</SP>, 54<SP>1</SP>, respectively extend through and intermediate the teeth of an internal gear ring of the ring 44, the rotary elements 46, 48 comprising gear pinions rotated by engagement with the internal gear teeth. In the Figure 4 embodiment, the rotary elements 46a, 48a comprise cylindrical surfaces, co-operating with a cylindrical inner periphery of the ring 44a and rotated by interengaging gear teeth 47, 49 respectively around the upper ends of the ring 44a and the elements 46a, 48a. Alternatively, Figure 6 (not printed), the teeth 47, 49 may be absent and the cylindrical elements (46b, 48b) may be freely rotatable. The pellets 60 may be broken upon contact of the extrusion with an exhaust shoot 16. The snow 23, Fig. 1, is delivered into the ring 44 by a horn 12 into which it is flashed at a nozzle 22, supplied with pressurized liquid CO 2  from a supply at 10, via precooling coils 35 surrounding a stainless steel housing 26 which supports the horn 12, at its upper end, and at its lower end at resilient struts, 13, and which also defines a snow enclosure 28 from which excess CO 2  gas is vented, at 30, to a recycling outlet 36, via a manifold 32 and coils 34, which act to cool the chamber 28 and subcool the coils 35. The ring 44 is bolted to an annular retaining ring 64 (which also supports the housing 26 and a surrounding insulating jacket 38) supported on a fixed housing H, and to a lower plate 66 bolted to a bearing housing 27 for the shaft 18. CO 2  snow is cleared from the upper flat surfaces of the rolls 46, 48 by an inner extension 90 of the retaining ring 64. The axis 12<SP>1</SP> of the horn 12 may be inclined to the axis 14<SP>1</SP> of the carrier 40 to deposit the snow 28 eccentrically within the ring 44, the horn 12 being mechanically vibrated, to prevent adhesion of snow to the interior thereof, by an arm 100 of a spring steel strip 96 attached at one end to the housing 26 and the other end whereof is oscillated by engagement with a star wheel or pegs 94 extend - ing from the shaft 18. Alternatively, Fig. 4, the horn 12 may be symmetrically located with respect to the shaft 18 with the snow 28 distributed radially into the ring 44 by a cone 104 seated around the axis of the carrier 40, with spreading of the snow 28 being assisted by a strip 106 extending inwardly from the housing 26. The horn 12 and housing 26 may also be vibrated by an electrical vibrator 105 attached to the jacket 38. The shaft 18 is rotated from an electric motor M, via a belt and pulley drive 110, 108 and 112, acting through a spring loaded clutch 120. The carrier 40 comprises a central hub 74 keyed at 42 to the shaft 18, and from which extends parallel spaced arms, 76, 78 supporting, at bushings 84, 85, bearings 86, 88 for the elements 46, 48.