US2217934A - Moistening tobacco for stemming - Google Patents

Description

Oct. 15, 1940. BAER 2,217,934

MOISTENING TOBACCO FOR STEMMINE Filed Oct. 7, 1937 jive/Z307 1-7 0727? fifiaer g; Z6295; XM am; M W.

Patented Oct. 15, 1940 UNITED STATES MOISTENING TOBACCO FOR STEMMING John M. Bacr, Chicago, Ill., assignor to The Guardite Corporation, a corporation of Illinois Application October 7, 1937, Serial No. 167,858

Claims. (Cl. 131-140) This invention relates to a method of stemming tobacco and more particularly to a method of treating dry brittle tobacco to render it soft and, pliable and then stemming the material 5 while still in a soft pliable condition.

In the present tobacco treating methods, tobacco is stored in large hogsheads in which from 1,000 to 1,600 lbs. or so of tobacco are held under very considerable pressure. When the storage period is over, this tobacco is in an extremely dry and brittle condition and can not be handled without considerable breakage. As a result, it has been uniformly customary to moisten this tobacco in a steam or ordering room, in which the moisture content of the tobacco is increased from 2 to 3%, and its temperature slightly raised. A dry tobacco normally has a moisture content of from "I to 9%, which is therefore raised to around 10 to 12% 20 in the ordering treatment.

The so-treated tobacco is then satisfactory for grading, but the moisture content is not sufllcient so thatthe material can be immediately put through stemming machines. Instead, the hogsheads are broken down and the material'placed on conveyers, which carry it through a steam tunnel or ordering chamber, wherein the moisture content is further increased, and from which the tobacco is immediately passed to stemming 30 machines, whereinit is stemmed.

It has now been discovered that if the moisture content of tobacco is increased initially to approximately 15 to 17%, it may be then directly stemmed without the use of the steam 3.3 tunnel. Such a process has enormous advantages in the saving of expense and also in avoiding the losses of aromatic materials by distillation in the steam tunnel.

The invention is illustrated diagrammatically ".gfiin the drawing in which: I0 represents a vacuum chamber provided with doors H, a steam line I2, a water line I3, and an evacuating line It. A hogshead of tobacco l5 may be placed inside the vacuum chamber and treated as hereinafter described.

, In accordance with this invention, dry tobacco, having say a moisture content of 9%, is treated in the hogsheads with steam and liquid water suflicient to raise its moisture content to 15 to 17%.

In carrying out the process, the bulk tobacco is placed in a gas-tight chamber and subjected to a high vacuum, suflicient to reduce the temperature of the tobacco considerably. Normally, a vacuum of below 29 is necessary for this purpose. After the tobacco has been substantially freed in this manner from non-condensible gas, steam and liquid water are admitted to the vacuum chamber, the liquid water being preferably introduced in spray form at the high 5 vacuum. In this way the water has been found to penetrate to the center of the tobacco without raising its temperature as much as the steam does. During the first portion of the steaming period, it is preferred to continue evacuation, 10 this having a flushing efi'ect upon any remnants of non-condensible gas in the tank or any that may be introduced with the steam or water..

The admission of the steam will, of course, raise the temperature and pressure in the chamber, and it is preferred to stop the steaming operation before the temperature has reached a deleterious point. This will, of course, vary for different tobaccos, but it is preferred not to exceed about 175 F. for Burley tobacco and 160 F. for Virginia'tobacco.

The amount of moisture added is controlled by the amount of water admitted, and also by the increase in temperature. The amount which may be added in any one operation, however, is limited to about 10 to 12%. If more is desired, a further watering cycle may be employed.

Liquid water is preferably only admitted during a portion of the steaming operation, the steaming being continued and the temperature raised for a substantial period after the admission of liquid water has ceased. This additional steaming operation is preferred, because it tends to remove any wet spots which may have been produced by unequal spraying of the water. Preferably steam used in this portion of the procedure is slightly superheated.

With some tobaccos it is desirable, following the operation heretofore described, again to lower the pressure in the chamber to produce boiling of water. This second evacuation apparently removes traces of non-condensible gas, which may have been held in very tightly compressed portions of the hogshead, or in portions where the vapor pressure was extremely low, or it may remove non-condensible gas which has been brought in by the incoming steam or water that has collected in the center of the hogshead. This second evacuation preferably reduces the temperature at least 10 to 15 and is preferably fol- -lowed by a steaming operation to bring the temperature 'up materially, preferably to approximately the temperature existing before the second evacuation treatment.

The hot tobacco, which preferably has from 2 to 3% more moisture in it than is necessary in the stemming operation, is then removed from the vacuum chamber and promptly passed to the stemming machine, which may be of any conventional type, such as the Pasley stemmer.

In the transfer from the vacuum chamber to the stemmer, the tobacco passes through the open air and is materially cooled by contact therewith and by evaporation of the excess moisture.

It is preferred that the tobacco be hot when it is freed from the vacuum chamber, because. for a given moisture content, tobacco is more pliable when warm than when cold. Moreover, since some of the cooling in the air is done by contact with the air and by radiation, there is not as much loss of moisture as there would be in the chamber where practically the entire temperature drop must be due to evaporation of moisture.

As an example of the process, a hogshead of Kentucky Burley tobacco weighing 1,213 lbs. and having an initial temperature varying from 81 at the center to 83 F. near the outside, was placed in a vacuum chamber and evacuated until the temperature of the tobacco had fallen to 68 F. throughout. This took a period of about 20 minutes and the absolute pressure reached about'0.3". Steam was then admitted for 14 minutes to raise the temperature in the tobacco to approximately 164 F., and then a vacuum was again drawn to reduce the temperature to approximately 134 F. at the center of hogshead. This took about 10 minutes and the mercury indicated a pressure of approximately 3.9" at the end of the evacuation cycle. Steam was then again admitted to bring the temperature up to 164 F.

In the first steaming period of this operation, 20 gallons of water were sprayed into the tank with the steam during the first 2 minutes of the steaming period. The last 12 minutes of the steaming period were with steam only.

The last steaming period required only about 7 minutes, or a total of 51 minutes for the entire operation. Evacuation was continued for the first 3 minutes of the firststeaming cycle.

During this operation, 91 lbs. of water, or approximately 7.5% by weight, was added to the hogshead. The hogshead was free from cold or dry spots and was in satisfactory condition.

In another example of the process, Virginia tobacco in a hogshead weighing 1,178 lbs. and having a temperature of 81 F. at the center was subjected to a vacuum suflicient to produce a temperature of 68 F. in the center. This required about 20 minutes and the barometer at the end of the period was approximately 0.38" absolute. Steam was then introduced with 20 gallons of water for 2 minutes, and the steaming operation continued for 3 minutes further. The

chamber was then evacuated for 10 minutes and then steam was admitted for 13 minutes, to produce a temperature of approximately 150 F. in the center of the hogshead. Tobacco was then evacuated again until its temperature had dropped to F. after 10 minutes, and was then steamed for 9 minutes to produce a temperature of 157 F.

At the end of this time the tobacco had gained 89 lbs. in weight, or somewhat more than 7%.

The tobacco was in excellent condition for handling and was free from dry spots.

Tobacco treated by this process not only completely passes directly to the stemming machines, but when stemmed produces pliable stems as distinguished from the frequently brittle stems resulting from sweat room plus ordering chamber operations.

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

I claim:

1. In a tobacco treatment process, the successive steps of subjecting the tobacco to a high vacuum, supplying a mixture of steam and water in mist form to the tobacco whereby the absolute pressure thereon is increased from the initial vacuum value to a higher but sub-atmospheric pressure, and then subjecting the tobacco to an increased vacuum sufiicient to cause evaporation of moisture therefrom whereby the tobacco is cooled.

2. In a tobacco treatment process, the successive steps of subjecting the tobacco to a high vacuum, supplying to the evacuated tobacco steam and finely divided water vapor entrained therewith, the amount of water so supplied being in excess of an amount sufficient to saturate the steam supplied at the subatmosperic pressures prevailing and then subjecting the tobacco to an increased vacuum suflicient to cause evaporation of moisture therefrom, whereby the tobacco is cooled.

3. A process for treating tobacco comprising subjecting the tobacco to a high vacuum, supplying to the tobacco a mixture of steam and water whereby the absolute pressure on the tobacco is increased and moisture is added thereto, and re-evacuating the tobacco sufficiently to cause evaporation oi some of the moisture therefrom.

4. A process for treating tobacco comprising subjecting the tobacco to a high vacuum, supplying to the evacuated tobacco steam and finely divided water entrained therewith, the amount of water so supplied being in excess of an amount suflicient to saturate the steam supplied at the sub-atmospheric pressures prevailing, increasing the vacuum on the tobacco suiliciently to cause evaporation of moisture from the tobacco whereby the tobacco is cooled.

5. In the bulk treatment of organic products,

the successive steps of removing from the product substantially all non-condenslble gas, supplying thereto a mixture of steam and water, the water being in mieromist form, and being supplied to the product in a carrier of steam, whereby the steam carries the particles of water substantially uniformly throughout the bulk of the product andcondenses therein, leaving the water distributed therethrough, and then subjecting the product to an increased vacuum sumcient to cause evaporation of moisture therefrom, whereby the product is cooled.

JOHN M. BAER.

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