US2516118A - Moistening of tobacco - Google Patents

Description

Patented July 25, 1950 Arnold H. Heineman, Chicago, 111., assignor, by mesnc assignments, to Guardite Corporation, Wilmington, DeL, a corporation of Delaware No Drawing. Application March 22, 1946, Serial No. 656,518

1 Claim.

This invention relates to the treatment of tobacco and more particularly to the treatment of tobacco in large masses such as hogsheads.

Tobacco is normally picked with the leaves as complete as possible on the stems and the stems are then tied together near the base of the leaf to form what is known as hands.

Tobacco is then suspended in hands for drying and curing, and after appropriate treatment, is stored in hogsheads. the hands of tobacco are laid carefully upon each other, the leaves being fiat and the hands usually being arranged circumferentially around the vertical axis of the hogshead. High pressure is applied to the tobacco before crating the hogshead. The ultimate hogshead is about 4 to 5 feet across and 4 to 5 feet high and contains upwards of 400 pounds of tobacco. These hogsheads are then stored for long periods of time for proper seasoning of the tobacco, or for other reasons.

During storage the tobacco becomes quite dried and cannot be unpacked without excessive breakage of the leaf material. For this reason the hogsheads are moistened before unpacking. The

present preferred method of treatment is perhaps best described in Baer Patent 2,196,183.

In view of the fact that the stored tobacco is made up of many different leaves, and the leaves themselves consist of stem material as well as leaf material, it cannot be expected that the moisture content of the material within the hogsheacl will be uniform at the beginning of the treatment. Furthermore, since previous processes for moistening have advocated the use of saturated steam or even supersaturated steam in order to bring about the maximum moistening, initial difierences in moisture content tended to be preserved throughout the treatment. The present invention provides a method of promoting uniformity of moisture content.

This result is accomplished by using, instead of saturated steam, steam which is substantially superheated, and repeating the process as an incident to a moistening process, even though the superheated steam cycle will result in an overall lowering of the moisture content of the tobacco.

In the operation disclosed in said Baer patent, tobacco in hogsheads is placed in a vacuum chamber, the air is removed therefrom and an atmosphere of steam at low absolute pressure is substituted therefor.

Saturated or supersaturated steam, or at least steam as saturated as is obtainable, is then introduced markedly to raise the pressure on and the temperature of the tobacco, thereby increas- In forming the hogsheads ing the moisture content of the tobacco. The pressure is then reduced and the steaming step thereafter repeated, this cycle being normally gone through several times. In the present process these steps may likewise be followed except that one or more of the steaming steps, and preferably several of the steaming steps, are performed with steam having substantial superheat. Sufficient treatment with saturated or supersaturated steam is applied, however, so that the moisture content of the tobacco is appropriately increased.

As was mentioned above, saturated or supersaturated steam acts to add moisture substantially uniformly throughout the tobacco mass, so that initial differences in moisture content of the tobacco tend to be preserved throughout the cycle of treatment with saturated stem. superheated steam, on the other hand, tends to remove moisture from the tobacco mass. Peculiarly, however, during the slight drying which occurs with introduction of superheated steam, initial difierences in moisture content tend to disappear. The superheated steam appears to be effective in producing uniformity of moisture content because of the difference in specific heat in a moist product as compared with a dry product. Inasmuch as water has a considerably higher specific heat than dry organic products, as the moisture content of such a product increases, its specific heat increases. Therefore, when the product is heated with superheated steam, those parts which are dry will acquire less caloric heat content on a given increase in temperature and will, therefore, lose iess moisture under evacuation than do those parts which initially contain more moisture. Absorption of moisture by the tobacco, on the other hand, is not dependent upon the specific heat of the tobacco; so that this levelling off of moisture diiierential does not take place during the treatment with saturated steam.

It is preferred that the steam used be at least 25% superheated.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom.

What I claim as new, and desire to secure by Letters Patent, is:

In the moistening of dry, aged tobacco in hogsheads in a process which comprises subjecting a hogshead of tobacco which has less than the desired moisture content to a low absolute pressure in an atmosphere substantially of steam and then cyclically increasing the pressure of the steam and the temperature of the tobacco and again reducing the absolute pressure to cause the boiling of water from the tobacco, at least some of the pressure increasing steps being carried out with saturated steam, the step of introducing, during at least one of said pressure increasing steps, steam which is superheated at least 25%, whereby inequalities in the initial moisture content of the various portions of the tobacco are substantially reduced.

ARNOLD H. I-IEINEMAN.

4 REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS