GB439819A - Improvements in or relating to methods of and apparatus for rendering powdered materials fluid - Google Patents

Abstract

439,819. Emptying storage chambers from below ; pneumatic conveyers. AHLMANN, N., 7, Taarnborgvej, Copenhagen. June 15, 1934, No. 17792. [Classes 78 (i) and 78 (iv)] [See also Group XVIII] In order that powdered material such as cement, cement raw meal, pulverized coal, pigments, &c., contained in weighing, measuring, transporting, or storage apparatus may behave as if it were a liquid, air under pressure is added to it, in a periodically interrupted, or continuously pulsating, current without the use of mechanical stirrers. In the case of a silo provided with a worm conveyer in its bottom to discharge the contents through a gate, the air is introduced in proximity to the worm. In one construction a container 1, Fig. 1, communicates with a chamber 20 at the end of a compressed air supply pipe 3, when the spring-loaded valves 2 are lifted by opening the cock 4. This cock is rotated continuously by a chain drive 5 at a uniform speed so that air is admitted and cut off at regular intervals of, e.g. one or two seconds. The pressure is prevented from fluctuating too considerably by inserting a chamber 6 in the pipe 3 before the cock 4. In another construction a spring-loaded lift valve has two seats 7, 8, Fig. 2, of different sizes and carries an armature 12 which cooperates with magnets 13, 14 that tend to retain the valve in its end positions. When the pressure in the compressed air vessel reaches a predetermined amount, the valve will open and the armature 12 will move to the magnet 13 and be retained until the pressure of the air on the valve has decreased sufficiently to allow the spring 15 to return the valve to the closed position. In a further construction the spindle of a lift valve is connected to a spring-loaded piston movable in a closed cylinder, one end of which is formed with an aperture through which compressed air is supplied periodically.