Process and apparatus for impregnation and expansion of tobacco

摘要

A process for expanding tobacco is provided which employs carbon dioxide gas. Tobacco temperature and OV content are adjusted prior to contacting the tobacco with carbon dioxide gas. The disclosed process is suitable for impregnating and expanding tobacco having a high bulk density. In order to achieve a high bulk density, the tobacco may be compacted or compressed to achieve an increased and more uniform bulk density prior to its impregnation with carbon dioxide. The process may be carried out with a short cycle impregnation in an apparatus according to the invention. A thermodynamic path is followed during impregnation which allows a controlled amount of the carbon dioxide gas to condense on the tobacco. This liquid carbon dioxide evaporates during depressurization helping to cool the tobacco bed uniformly. After impregnation, the tobacco may be expanded immediately or kept at or below its post-vent temperature in a dry atmosphere for subsequent expansion.