GB1022541A - Improvements in pulverizing mills - Google Patents

Abstract

1,022,541. Beater mills. BABCOCK & WILCOX Ltd. Nov. 12, 1962 [Nov. 11, 1961], No. 42652/62. Heading B2A. In a mill for pulverizing and drying material, e.g. raw brown coal, comprising a staged beater mill section 1, Fig. 1, and a fan mill section 2, the beater mill section is formed so that the diameters of adjacent mill stages are different, and the diameter of the last beater mill stage is not greater than the diameter of the inlet aperture 41 of the fan mill section. The beaters 11 are arranged in three annular rows, and are respectively, equi-angularly spaced around a shaft 3, each row together with the lining 9 secured to the casing 8, constituting a stage. Material and gas delivered through an inlet 6 are prevented from entering the first stage radially inwardly of the path swept by the beater heads by a plate, rotating with shaft 3, comprising a cover disc 24 and a curved plate reinforcement 25. In a further embodiment, the protective structure 24, 25 is replaced by an oval plate inclined downwardly and inwardly towards the first beater stage and attached to a stationary shaft projection tube extending around the mill shaft 3, a complementary curved member being welded at one edge to the edge of the plate. A disc 34 secured to the shaft hub 12 separates each mill stage, but can be dispensed with where the beater heads are mounted on arms which broaden towards the hub to which they are secured, Fig. 5 (not shown). The fan mill section 2 comprises a rotor having a circular row of vanes 21 extending around the axis of shaft 3. The vanes are located between a disc 18, secured to a hub 17 of the shaft, and an annular disc 19, axially spaced from disc 18, and connected to disc 18 by cross-members 20, the vanes being removably secured to discs 18 and 19. The fan mill inlet aperture 41 is outwardly defined by the inner edge of the annular disc 19. Material is led into the fan mill section by a short transition shaft 23, whose inner surface is flush with the inner surface of a section 9 of wear resistant material, which is of smaller diameter than the last of the beater mill stages. A three stage beater mill section may be formed with the first and third stages of equal diameters and the second stage of either greater or less diameter, the linings 9 associated with the smaller diameter stage or stages being made thicker than that of the other or others. The beater heads of one beater stage may be staggered with respect to the beater heads of an adjacent beater stage.