| 摘要 |
In a process for expanding tobacco, an equilibrium pressure within a process vessel (1) containing a mixture of gaseous carbon dioxide and liquid carbon dioxide is selected before charging a sample volume of tobacco from a batch of tobacco into a sealable impregnator vessel (2). Liquid carbon dioxide is then transferred at the selected equilibrium pressure from the process vessel (1) into the impregnator vessel (2) where it is maintained sufficiently long to permit liquefied carbon dioxide to penetrate the cells of the tobacco. Liquid carbon dioxide is subsequently transferred from the impregnator vessel (2) into a drain vessel (3) and the pressure within the impregnator vessel (2) is reduced sufficiently to cause the solidification of liquid carbon dioxide contained within the cells of the tobacco. Finally, the tobacco is heated sufficiently to vaporise the carbon dioxide in the tobacco cells thereby expanding the tobacco. The degree of tobacco expansion obtained is determined and the equilibrium pressure within the process vessel (1) is re-selected to control the amount of solid carbon dioxide formed during the de-pressurisation step of a subsequent impregnation cycle or cycles to optimise the degree of expansion of tobacco for the remainder of the batch. |
