Improvement of Process Gas Temperature Control in Oil-fueled Pneumatic Tobacco Drier

Controlling process gas temperature through its oil-fueled burner in a pneumatic dryer has the disadvantage of slow response, which leads to over regulation and wide fluctuation of moisture content and temperature of output cut tobacco. Therefore, a bypass duct for process gas was added, the temperature of process gas was regulated by interlinked air dampers to regulate both the air volumes into the burner and that into the bypass duct. The results showed that:the fluctuation range of drying temperature decreased from ±15℃ to ±1℃, the duration from temperature regulating to system stabilizing reduced from 180 s to 40 s, the fluctuation ranges of temperature and moisture content of output tobacco decreased from ±3℃ to ±1℃ and from 1% to 0.5%, respectively.