| 摘要 |
<p>VACUUM AND GAS EXPANSION OF TOBACCO Tobacco is expanded by cooling the same to a temperature of about 30.degree.F or less and subjecting such cooled tobacco to a subatmospheric pressure in a vessel. CO2 gas is then introduced into the vessel and contacts the cooled tobacco to impregnate the tobacco with CO2 gas as pressure in the vessel is brought to substantially atmospheric pressure. Subsequently, the cooled CO2 impregnated tobacco is subjected to conditions whereby the CO2 in the tobacco is removed and the tobacco is expanded. Typically, the CO2 impregnated tobacco is introduced into an expansion tower wherein it is heated to increase the volume of the CO2 and to expand the tobacco in size. BACKGROUND OF THE INVENTION The present invention relates to methods for expanding tobacco and more particularly to methods wherein a gaseous agent is utilized to impregnate the tobacco under relatively low pressure conditions prior to expansion. In the course of cutting, curing and otherwise preparing tobacco for use in the manufacture of smoking products such as cigarettes, the density of tobacco is increased relative to the density of tobacco in a natural condition. Thus, the processed tobacco utilized in the manufacture of cigarettes is frequently of a density greater than is necessary for producing acceptable smoking products. Various techniques, as will be subsequently discussed, for reducing the density of such tobacco have been proposed in</p> |
