Shut-off device before a mill

摘要

The invention relates to a shut-off device before a mill for shutting off the smoke gas return with a telescopically adjustable sealing cylinder, which is arranged on a tubular extension of the smoke gas return, in a steam-generator mill furnace operated with fan mills. The problem of the invention consists in a shut-off device, which compensates vertical movements and vibrations, with a sealing cylinder which is completely sealed in relation to a closed slide or the inlet box of the mill, in order to prevent secondary air participating in the combustion or hot furnace gases escaping during operation. According to the invention, the aim is essentially achieved by the outer casing of the lower part of the round smoke gas return shaft (2) being designed as a sliding surface with roundness with exacting tolerance and being sealed with a soft material seal (14) in relation to the sealing cylinder (5) which is positionally defined and guided by means of spindle lifting gears (22, 25, 27, 28) distributed uniformly on the circumference with a vertical spindle (31), the spindle lifting gears (22, 25, 27, 28) being moved, by angularly movable couplings, positively with a common electromotive drive (18). <IMAGE>