Apparatus for expanding tobacco and method of expanding tobacco

摘要

In the present invention, there is disclosed an apparatus for expanding tobacco with a gaseous medium, the apparatus comprising an arcuate, generally C-shaped duct (16) for conveying the tobacco material in a hot gaseous medium to sublimate the solid carbon dioxide and expand the tobacco. The duct has a non-circular cross-section, preferably a rectangular cross-section, with a high width-to-depth ratio and an increasing depth from the inlet (34) to an intermediate portion (76) of the duct then a decreasing depth from the intermediate portion to the outlet (35) of the duct. A winnower device (48) infeeds the tobacco material into the duct adjacent the throat (26) of a venturi section (12) connected to the inlet (34) of the conveying duct. Said venturi section (12) includes a venturi inlet tube (22) and a venturi outlet tube (24) and both said tubes (22, 24) are connected to each another at the throat (26) wherein said venturi inlet tube (22) passes in the throat (26) away from a circular cross section to a rectangular cross section. Said venturi outlet tube (24) has rectangular cross section extending from the throat (26) to the conveying duct (16) inlet (34). Gaseous medium supply means are connected with means for supplying tobacco material into the tubular venturi section (12). The tobacco expansion method using impregnated solid carbon dioxide is characterized in that impregnated tobacco is introduced into the tobacco conveying duct (16), a gaseous medium heated to a temperature about 343 degC is introduced into said conveying duct (16) inlet (34) at a flow volume ranging from 849.48 me3.mine-1 to 1019.376 me3.mine-1 and at a rate of substantially 40 m.se-1. Said gaseous medium, being entrained by tobacco, flows from the inlet (34) toward the outlet (35) in substantially arcuate flow path of non-circular cross section enabling thus to sublimate the solid carbon dioxide and to expand tobacco in such flow path. The flow rate of the gaseous medium and the tobacco entrained thereby decreases from the inlet (34) to the outlet (35) and the expanded tobacco is thus separated from the gaseous medium.