Tobacco – Tobacco treatment – Puffing
Patent
1996-10-10
1998-01-27
Millin, Vincent
Tobacco
Tobacco treatment
Puffing
131296, 131900, A24B 318
Patent
active
057113190
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to the expansion of tobacco using carbon dioxide.
BACKGROUND ART
In a dry ice expanded tobacco, or D.I.E.T., process currently in operation at a tobacco expansion plant in Corby, England, tobacco is firstly loaded into an impregnator vessel which is subsequently sealed. The atmosphere within the impregnator vessel is then purged with low pressure gaseous carbon dioxide obtained from a charge vessel. Once all the air has been forced out of the impregnator vessel via a vent to atmosphere the vent is closed and the impregnator vessel is pressurised by gaseous carbon dioxide initially from the charge vessel and subsequently from a process vessel containing an equilibrium mixture of gaseous carbon dioxide and liquid carbon dioxide. The impregnator vessel is then re-connected to the charge vessel and simultaneously, the impregnator vessel is connected to the liquid carbon dioxide phase within the process vessel and the pressure difference which exists between the process vessel and the charge vessel causes liquid carbon dioxide to be transferred from the process vessel into the impregnator vessel to totally immerse the tobacco in liquid carbon dioxide.
Once the liquid carbon dioxide level within the impregnator vessel has reached a pre-determined level the impregnator vessel is isolated from both the charge vessel and the process vessel. The liquid carbon dioxide is maintained within the impregnator vessel sufficiently long to permit liquid carbon dioxide to penetrate into the cells of the tobacco. Following this, the impregnator vessel is reconnected to the process vessel to transfer liquid carbon dioxide which has not been absorbed by the tobacco back into the process vessel under the action of gravity. The impregnator vessel is then once again isolated from the process vessel and a connection established with a recovery system and consequently with a recovery balloon to allow the pressure within the impregnator vessel to reduce to cause the liquid carbon dioxide within the tobacco cells to solidify. Gaseous carbon dioxide from the impregnator vessel is collected and returned to the process vessel via the gas recovery system which reliquefies the gas. The impregnator vessel is then opened to allow the frozen tobacco to fall out and finally the tobacco is heated within a sublimator to cause the solid carbon dioxide within the tobacco cells to vaporise rapidly thereby expanding the tobacco.
The operation of the Corby plant relies on the transfer of liquid carbon dioxide from the process vessel to the impregnator vessel by means of the differential pressure which is maintained between the process vessel and the charge vessel. There is a delicate balance of pressure between the different parts of the system and consequently this and indeed other processes are designed to operate at a single impregnation pressure, such as 450 psi, which is used to expand all types or blends of tobacco, from any origin, which is sent to the plant. This pressure expands some tobacco product by anything up to two hundred percent whilst only expanding other tobacco product by around thirty to forty percent. The cost of achieving these two quite different degrees of expansion is the same.
DISCLOSURE OF THE INVENTION
According to a first aspect of the present invention, a process for expanding tobacco comprises the steps of: mixture of gaseous carbon dioxide and liquid carbon dioxide; impregnator vessel; from the process vessel into the impregnator vessel; sufficiently long to permit liquefied carbon dioxide to penetrate the cells of the tobacco; the solidification of liquid carbon dioxide contained within the cells of the tobacco; tobacco cells thereby expanding the tobacco; 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.
By changing the equilibrium pressure within the process vessel it is possible to optimise the degree of expansion f
REFERENCES:
patent: Re32014 (1985-10-01), Sykes et al.
Anderson Charles W.
Messer UK Limited
Millin Vincent
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