GB934088A - Improvements in or relating to abrasive-blasting systems - Google Patents

Abstract

934,088. Ventilating. VACU-BLAST Ltd. Oct. 17, 1961, No. 37143/61. Class 137. [Also in Groups XXIII and XXVIII] A floor 18 for an abrasiveblast room 11, preferably having downdraught ventilation, comprises a multiplicity of small hoppers 19 arranged in rows adjacent conveying ducts 21 the lower level of which is substantially in the same plane as the bottom of the hoppers; an orifice 20 on at least one side of each hopper 19 connects the hopper to an adjoining duct 21 and provides for the passage therethrough of the ventilating air and the spent abrasive and resulting debris, the latter being carried through the ducts 21 by the ventilating air stream. The abrasive is separated from the air stream in a concentrator 22 from which it is drawn through a conduit 27 by means of a fan 28 associated with a cyclone reclaimer 23, e.g. a centrifuge. The air stream, in which dust is entrained, is drawn by a fan 26 from the concentrator 22 to a dust separator 25, e.g. a bag filter or wet precipitator, the cleaned air from which is exhausted to atmosphere or recycled to the room 11; air from the reclaimer 23 passes from the latter through conduit 29 back to the concentrator 22 to join the main air stream. The floor 18 is preferably provided with an overlying perforated steel plate 17; alternatively, the floor may be provided with a wire mesh. The hoppers 19 are formed by a series of parallel longitudinal members 35 having cross-sections of inverted V-shape, the members 35 being welded to a base-plate 38 and secured in the troughs formed therebetween, e.g. by welding, are diamond-shaped partitions 43. The ducts 21 are formed by the underside of alternate members 35; if required, at least some of the other members 35 may all be used as conveying ducts, the adjacent hoppers being accordingly provided with additional orifices. The orifices 20 vary in size from one end of each duct 21 to the other, to ensure uniformity of air flow velocity through the orifices. The members 35 have openings 48 leading into the ducts 21 at the upstream end thereof; the openings 48 are protected by a baffle 46 thus ensuring an initial flow of air through the ducts 21. The flow cross-section of each of the latter increases progressively from the upstream end to the downstream end, a vertical V-shaped filler portion 50 being provided to which is attached a covering portion 56. The outlets 65 of the ducts 21 terminate in the lower part of the concentrator 22, the air stream being deflected upwardly by a plate 67 which may have a wearing surface 70 of rubber. A twisting path for the air stream is provided by baffles 71, 72 vertical baffles 75 being provided along the length of the concentrator 22 to ensure air flow in an upward direction. The abrasive separating from the air stream is caught by a row of spaced, inclined troughs 80 which deliver the abrasive through apertures (not shown) into a collecting duet 82 which is connected to the conduit 27. Specification 794,528 and U.S.A. Specification 2,912,918 are referred to.