GB526006A - Improvements in or relating to apparatus for drying wet materials - Google Patents

Abstract

526,006. Mills and apparatus. GROVES. W. W. (Combustion Engineering Co., Inc.). March 6, 1939, No. 7251. [Class 59] In apparatus for drying wet material comprising a drying and pulverizing mill 7, a furnace 3 arranged to supply drying gases to the mill, a mixing device 27 arranged to receive raw wet material to be dried from a hopper 24 and dried material from a cyclone 13 to be mixed with the material, a duct 2 for carrying the mixed material from the mixing device to the mill, a duct 11 for conveying gases and material from the mill to the separator 13 and means 15 for conducting the gases from the separator to a fan outlet, damper means is provided in a duct 37 connecting the fan outlet with the mixing device and in the duct 2 for carrying material from the mixing device whereby the pressure in the mixing device can be adjusted to a value differing slightly from atmospheric pressure. As shown, dried material from the hopper 13 is distributed in known manner in desired proportions between a discharge outlet 29 and a feed inlet 25 of the mixer 27 where it is mixed with raw wet material from the hopper 24. The pressure in the mixer 27 is maintained at atmospheric or sub-atmospheric pressure by controlling dampers 39, 41, and since these dampers are in the return air-flow pipes 37, 2, they also control the amount of hot gas withdrawn from the furnace 3. The damper 39 is controlled by pressure responsive means 51 and the damper 41 by a thermostat 43. The surplus gas in the system is discharged through a vent 33 and in a modification the surplus air, which is too great a volume to pass through the mixer, is conveyed by a pipe from the pipe 37 to the pipe 5, the volume so diverted being controlled by a damper operated by a thermostat. In another modification the surplus air is diverted from the pipe 37 to the furnace 3.