Patent GB-719716-A (GB)
Title: Apparatus for producing a suspension of finely divided solid materials in gaseous media
IPC: B01F23/30
Filed: 1951-12-13
Abstract: 719,716. Grinding-apparatus. KOPPERS GES., H. Dec. 13, 1951 [Dec. 14, 1950; May 7. 1991], No. 29225/51. Class 59 [Also in Groups XXVI and XXX] In apparatus for producing a mixture of a gas with a finely divided solid in which the finely divided solid is disintegrated in a grinding device consisting of a rotary head and a co-operating fixed crown and upon discharge from the grinding device is engaged and entrained by the gas, an annular passage is provided at the periphery of the grinding device into which passage open one or more inlet nozzles or passages for the gas so that a swirling gas flow is produced in the annular passage along the periphery of the grinding device. In the form shown in Fig. 1, the finely divided solid supplied to a container 3 is drawn between a rotary ribbed grinding head 5 and a fixed ribbed grinding crown 4 so that any agglomerations of the solid are removed. The completely disintegrated solid is discharged at the periphery of the grinding device through an annular slot 9 and passes into an annular passage 10 into which open one or more gas inlet nozzles, the nozzles being arranged tangentially to the passage 10 and being slightly inclined to the plane of the passage as indicated at 17. The gas flow removes the finely divided solid issuing at the edge of the grinding device and forms with it a practically homogeneous suspension which is taken off in a helical movement and withdrawn at 22. In a modification, Fig. 3, the finely divided solid from a hopper 30 is supplied by means of a rotary conveyer worm 31 to a grinding device consisting of a rotary head 34 and a fixed crown 35. Gas is supplied through tangentially directed nozzles 68 and the suspension taken off at 47. The shaft 36 of the head is yieldably held so that the head can move axially relatively to the fixed crown if too much solid is supplied by the conveyer 31. The mounting for the shaft 36 includes a lever 41 which can be connected with an indicating or alarm device and, if desired, with a regulating device so as to vary the speed of rotation of the grinding head if the conveyer delivers too much material. In another modification, Fig. 4, the material is supplied from a hopper 50 to a conveyer worm 51 the shaft 52 of which enters a housing 53 through a stuffing box 54. and carries the grinding head 55 which co-operates with a part of the housing provided with ribs 56. The grinding chamber opens into an annular chamber 58 provided with tangential inlet nozzles slightly inclined to the plane of the annular chamber, as indicated at 60. The mixture is discharged tangentially through one or more openings 61. Connected to the grinding head is a cylindrical part 62 which is sealed from the housing 53 by means of a stuffing box 63. The bore of the housing is provided with annular grooves 64 to which a gas is supplied through an opening 65. the pressure of the gas in the grooves being maintained higher than that of the gas in the chamber 58 so as to prevent the finely divided solid from passing into the region of the soft packing 66 and wearing it away. In a further modification, Fig. 6, a fixed housing 101 has a branch pipe 106 for delivering finely divided material, e.g. pulverized fuel, to a worm conveyer 107 which conveys the material to a grooved grinding head 113 mounted on the shaft 108 of the conveyer worm and co-operating with a fixed grooved grinding crown 114 so as to remove any agglomerations in the material. The finely divided solid issues at the edge of the grinding device and passes into an annular passage 115 into which open a number of substantially tangential nozzles 116 for a gas. The gas stream entrains the solid material and disintegrates it. The suspension is withdrawn through passages 117. The bore of a fixed housing part 118. into which fits a rotary guide body 119. is provided with screw threads 120 to form helical passages opening to a passage 121 which is connected by branch pioes 122 with a conduit for a gaseous blower medium. The apparatus is provided with a stuffing box 123. Only sufficient gas enters the helical passages to prevent the finely divided solid from gaining access to the stuffing box. In a still further modification, Fig. 9 (not shown), the tangential inlet nozzles are omitted and the screw threads. which are multi-start. are provided on the rotary guide body instead of in the bore of the fixed housing part. The whole of the blower medium is delivered through an annular passage to the helical passages and thence to the annular passage of the grinding device. In a further modification, Fig. 10 (not shown), the rotary guide body is carried on a shaft separate from and co-linear with that of the grinding head and the annular passage leading to the helical passages is provided with a branch pipe which forms a connection to an axial passage provided in the shaft carrying the rotary guide body and which opens into a chamber provided between a part of the grinding head and the guide body this chamber being provided with a small partial stream of the blower medium so as to prevent the solid material from penetrating into the chamber. In another modification. Fig. 11 (not shown). a fixed disc provided with helical grooves is disposed behind the guide body so that according to the speed of rotation of the guide body, the supply of gas to the passage system in the guide body is momentarily interrupted so that pulsations are formed in the current of the blower medium. In the last two constructions, the grinding head is held resiliently so that it can be moved axially outwards from the fixed crown.