| 摘要 |
1,222,033. Drying granular products. CHARBONNAGES DE FRANCE. 29 April, 1969 [30 April, 1968], No. 21839/69. Heading F4G. [Also in Division G3] In a system for drying granular material, the material is transported by conveyer screws through a trough and then passes down through a vibrating shoot, the temperature below the trough being maintained constant by automatic control of resistance heating and the temperature of the dried material being maintained constant by automatic control of infra-red radiation heating above the trough and shoot. In Fig. 1, granular material such as coal is supplied to a cylindrical hopper 4 made of tetrafluoro-ethylene to reduce sticking. The material is agitated by a rotating fork 11 and supplied through an outlet to a pre-heating oven 2 by an adjustable speed continuously or intermittently rotating paddle wheel 8. The temperature of the aluminium lower portion of the oven is mainted constant by a thermostat 31 controlling an electric heater 16 in an on/off manner. Steam liberated during drying passes out through chimneys 20. The material is moved through the oven by screws 15 and supplied through an outlet to an inclined drying shoot 21 feeding a grinder 30. The temperature of the material emerging from the shoot, which is an indication of moisture content, is maintained constant by a thermostat 25 connecting infrared heaters 18, 23 at the top of the oven and shoot in series of parallel according to whether the temperature is above or below a predetermined value. Thermostat 25 comprises a thermocouple between an upper copper plate and a lower heat-insulating plate. |
