Patent GB-824663-A (GB)
Title: Apparatus and method for drying materials
IPC: F26B17/28
Filed: 1956-04-10
Abstract: 824,663. Drying apparatus. BAKER, D. S. April 10, 1956 [April 13, 1955], No. 10879/56. Class 34(2) Apparatus for drying fine wet material, such as powdered coal, chalk, sewage &c., comprises a steam- or water-heated cylinder 31, Figs. 1, 2, 3, driven by an endlessband conveyer 37 spaced from the surface of the cylinder, except at its ends, and closed at its sides by walls 92, 92<SP>1</SP>, Fig. 11, attached to a frame 30 supporting the apparatus. The conveyer is driven through chain gearing 42 and a gear box 40 from an electric motor 39 and drives the cylinder 31 through chains 38 attached to the edges of the conveyer and engaging rims 109 at the ends of the cylinder. The material is fed into a hopper 55 the bottom of which is closed by rollers 57, driven through belt-gearing and a gear box 64 from an electric motor 61, one of the rollers being corrugated circumferentially so that the material falls in strip form into a shoot 71. The shoot projects through an aperture in the wall 92<SP>1</SP> and discharges the material on to the lower run of the conveyer close to one edge thereof. The material is carried through the throat 54 formed between the cylinder and the conveyer and the space 53 in which it is heated. Material adhering to the conveyer is removed by a scraper 77, while that adhering to the cylinder is removed by a scraper 85. The removed material falls back on to the lower run of the conveyer and is again carried through the throat and the space 53. This action is continually repeated and the material gradually spreads along the length of the cylinder until it reaches the end thereof where after removal by the scraper 85 it falls into an adjustable hinged trough 94 at the upper end of a discharge shoot 91 which projects through an aperture in the wall 92. Moistureladen air is removed from the space 44 between the upper and lower runs of the conveyer through a port 65 in the wall 92. The port may be connected to an exhaust fan. The strength with which the material is drawn into the throat 54 is reduced by fingers 90, Figs. 3, 11, formed in a flexible curtain 88, e.g. of stainless steel, carried by a transverse member 87 suspended by hooks 86 from an angle 80 carrying the scraper 85, the fingers being pressed against the surface of the cylinder by the material entering the float. The conveyer consists of transverse angle members 102, Fig. 5, secured by bolts to the lugs 100 formed on interconnected yokeshaped links 96 forming the driving chains 38, the members being looped by overlapping flexible sheets 105, Fig. 8, secured by rivets 107 to the legs 103 of, e.g. every fifth angle member. The sheets are flexed to follow the curvature of the conveyer belt when is passes over counterweighted tensioning sprockets 47, Fig. 3, by spring-loaded arms 120 mounted on pivots 121 secured to brackets carried by a transverse angle 122. In a modification, the space 44 between the upper and lower runs of the conveyer is divided by a transverse partition and a partition in the direction of the length of the conveyer into two compartments each having an inlet for dry air and an outlet for moisture-laden air. In another arrangement, the cylinder consists of inner and outer drums 139, 140, Figs. 19, 20, the space 142 between which is connected by hollow arms 144 of streamline cross-section to the hollow ends of a shaft 141. In this case, steam is supplied to the space 142 through the arms at one end and condensate discharged through the arms at the other end. The cylinder is also formed with a drum 172 having a smooth inner wall and through which material discharges through the shoot 145 into the drum 172 passes in contact with a current of drying air to a final discharge shoot 146. The material is removed from the dry end of the cylinder by a scraper 173 so as to fall on to a screen 174 which permits the fine material to pass into the shoot 145, while the coarser material falls on to the lower run of the conveyer and returns to the throat and the space between the cylinder and the conveyer. Figs. 23, 24 show a modified apparatus in which the cylinder 150 is heated by a coal- or oil-fired return flue furnace 149, extending into the cylinder. In this case, the cylinder is supported upon rollers 152 and is rotated by a pinion driven by an electric motor and engaging a ring gear 155 on the cylinder. In another construction, the cylinder is heated by a perforate burner tube 181, Fig. 27, supplied with natural gas, butane or propane, and the products of combustion from which pass through the annular space between the internally-ribbed cylinder and an inner stationary drum 183 to an exhaust duct 197. Specification 593,444 is referred to.