GB1476364A - Method and apparatus for drying tobacco - Google Patents

Abstract

1476364 Drying tobacco HAUNI-WERKE KORBER & CO KG 15 July 1974 [14 July 1973] 31174/74 Heading F4G [Also in Division A2] A method of drying tobacco comprises the steps of supplying tobacco at a uniform rate, acting on the material during its conveyance through a first homogenization region by a first heated air or other gas current whose moisture content corresponds at least approximately to that of the tobacco supplied, so that the tobacco and gas are in hygroscopic equilibrium, drying the tobacco whilst it is conveyed through a drying region acting on the dried tobacco whilst it is conveyed through a second homogenization region by a second heated air or other gas current whose degree of moisture corresponds to the desired final moisture of the tobacco after drying, so that the tobacco and gas are in hygroscopic equilibrium, and discharging the dried and homogenized tobacco at a constant rate. In the apparatus shown a conveyor 8 supplies moist tobacco 7 to a conveyor weigher 12 which feeds it to a vibratory trough 11 where its moisture is monitored by a transducer 46. The tobacco then moves by way of a slide 20 to a vibratory trough 13 which passes through homogenization chambers 2, 4 and drying device 3 comprising chambers 26, 27, 28 connected by pipes 29, 30. A pipe 21 supplies moist air to the chamber 2 which passes through apertures 16 in the trough 13 for venting through a pipe 22. Heated air passes from pipe 31 into the chamber 26 and thence to chambers 27, 28 through pipes 29, 30 prior to venting through a pipe 32. Air conditioned to the moisture of the discharging tobacco by a transducer 71 enters the chamber 4 by a pipe 36 and is vented through a pipe 37. The signal from the transducer 46 passes to a control transmitter 53 and from thence to a comparator member 66 connected to a transducer 67 for controlling the temperature of the air in the heater 24 and to a transducer 56 for controlling the moisture content of the air via a comparator member 54 and an amplifier 57, controlling a motor 58 operating a pump 59 supplying moisture to an intake pipe 61 connected to the pipe 21. The comparator also controls a fresh air valve 62. A transducer 71 at the outlet of the trough 13 in conjunction with reference transmitters 75, 82, 97, control the predetermined final temperature and moisture for the chamber 4 and through a servo drive 76 controls a fresh air valve 77 in the heated air intake pipe 78.