Patent GB-1012569-A (GB)
Title: Improvements in or relating to pulverizers
IPC: B02C7/08
Filed: 1962-10-04
Abstract: 1,012,569. Impact pulverizers. B. J. PARMELE. Oct. 4, 1963 [Oct. 4, 1962], No. 37534/62. Heading B2A. [Also in Division F2] A pulverizer has lower and upper contrarotating rotors 53, 54, Fig. 1, mounted on lower and upper bearings in separate frameworks 12, 14, a pair of inverted seals 62, 63 being associated with the upper bearing of each rotor, a hopper 206 on top of the upper framework 14, a feed tube 78, Fig. 4, which connects the hopper centrally to a space between the rotors, which have annular projections 146, Fig. 5, staggered with respect to one another to form a zig-zag passage from the centre to the periphery, and means 234, 200 for collecting and separating the material so pulverized. As described, the frameworks of the pulverizer are hinged at 16, the upper framework being opened by operation of a motor-driven gear-wheel 20, Fig. 2, meshing with a toothed quadrant 18 so that rotor rings can be changed. A shaft 24, Fig. 3, which is supported by bearings located between the shaft and a concentric tube resiliently secured to the framework, carries a disc 52 at its upper end holding the concentric rings of the lower rotor 53. A plate disc 74 rests on a ring 74a welded to the tube 30, and has adjustable orifices 74e spaced equidistant around it to permit additional air to enter a chamber 74f, Fig. 1, to maintain a constant air velocity, adjustment being made by rotation of the disc 74. The disc 76 of the upper rotor 54 is driven via a shaft 75 supported by resiliently mounted bearings, with the concentric, replaceable feed-tube 78 surrounded by a spiral bar 78a, Fig. 4, to keep the space clear of dust and assure a flow of air. Each rotor ring, 52, 76 includes a concentric arrangement of an outer annular ring 146 and an inner locating ring 148, and an extension ring 150, Fig. 5. having a hard wearing tip 152 welded on to the remote end of each extension ring, under the lip of which is a hard-wearing ring 154 of e.g. sintered carbide, aluminium, porcelain, or tungsten steel, secured by a thin epoxyresin layer. The upper and lower rotor rings 76, 52 have casings 160, 162 bolted to the frameworks 14, 12 and sealed by a rubber ring 166. The outer periphery of the lower rotor is protected by a frustum of a cone 170 supported by brackets 172, and a baffle 174 protects the outer casing 162 against abrasive action of the pulverized material. The baffle may have a toothed surface, the teeth each comprising three faces 180, 182, 184 of a trapezoid, Fig. 7a, or it may be formed with regular gear-shaped, sloping, or ratchet-like teeth. In operation, pulverized material from the outermost ring of the upper rotor hits the baffle 174, part of the resultant dust being drawn up through the spaces 74m and i and conduits 74j, and passes through the separator top entrances 74k and joins the dust laden air that passes into separators 200. An exhauster (not shown) draws air from the parts of the pulverizer, some circulating through the hopper and cooling the lower bearings 26, 28, Fig. 3, after passage through a heat exchanger (where hot material is being ground). Coarse material slides down shoots 232a, b which join into a single shoot 232, strikes a shelf 74h and passes over replaceable louvres 74g, where regulated air, including some recirculated air, via a duct 236, separates by winnowing out fine dust particles, which are carried upwards through the shoots 232a, b to air/dust separators 200. The larger sizes of material are recirculated back to the hopper, an adjustable flap valve 240 providing additional classification via pipes 244, 246. Specification 995,163 is referred to.