US2989057A - Method of curing green tobacco - Google Patents

Description

June 20, 1961 ,.R. D. TOUTON METHOD OF CURING GREEN Filed Nov. 20, 1957 TOBACCO 2 Sheets-Sheet 1 FIG. 2.

FIG. 3.

INV ENT OR.

RUSH D. TOUTON ATTORN EYS June 20, 1961 R. D. TOUTON 2,989,057

METHOD OE OURINO GREEN TOBACCO Filed Nov. 2O, 1957 2 sheets-sheet 2 FIG. 4.

FIG. 5.

INVENTOR.

RUSH D. TOUTON BYW ATTORNEYS States Patent 2,989,057 METHOD F 'CURING GREEN TOBACCO Rush D. Tonton, Wynnewood, Pa. Wurton Machine Co., 9th and Columbia Ave., Philadelphia 22, Pa.) Filed Nov. 20, 1957, Ser. No. 697,566 8 Claims. (Cl. 131-140) 'Ihis invention relates to a method of curing green tobacco, that is, for removing'moisture from the tobacco to the desired extent, bringing the leaf to the desired color and providing the leaf with the desired aroma, grain, taste, elasticity and general soundness. The process in accordance with this invention isn-applicable, for eX- ample, to curing primed types of tobacco and wrapper tobacco leaves for cigars.

The method in accordance with this invention lis highly advantageous for a large number of reasons. It provides a more uniform color throughout all the leaves and resultsY in providing leaves having a superior texture. The improved results achieved with this process permit the employment of the higher leaves of the tobacco plant which have heretofore not been harvested due to the low price which they command after being cured by conventional processes.

In addition, the method in accordance With thisinvention represents a marked reduction in costs as contrasted to heretofore known processes. Since the method requires that the tobacco leaves be tightly packed, it is possible and indeed desirable to eliminate the employment of laths which permits the elimination of the time consuming operations of Stringing tobacco onto laths, hanging and removing the laths. The reduction in handling resulting from this method eliminates a substantial percentage of the breakage which occurs incident to the handling of the tobacco during the curing operation. Further, since the tobacco is relatively tightly packed in the curing compartment, a great deal more tobacco can be cured per cubic foot of curing compartment. This invention provides superior curing with buildings and equipment of less initial and maintenance cost than is involved using theV presently known methods of curing. Further, adequate equipment to provide the positive and accurately controlled conditions -for the optimum curing `is made practical in View of the decrease in space requirements for the green tobacco.

A further surprising advantage of this method is that when it is employed, the leaves undergo less shrinkage. This, in turn;` permits more cuts per leaf to be obtained after the tobacco is cured.

Finally, this invention provides the ready ability to soften and maintain the tobacco in proper condition for further handling after curing regardless of weather conditions.

The' method in accordance with this invention comprises forming a bed of tobacco leaves with the butts extending in one direction and forcing conditioned air through the bed preferably from the butt ends towards the tips of the leaves. Alternatively, the air can be passed` through the bed from t-he tips towards the'butt ends of the leaves. It will be understood that the term air includes air per se as well as air mixed with the gases produced during the curing and as well as with other lgases used in curing s-uch'as ethylene oxide. The bed of tobacco leaves will be formed so that the adjacent tobacco leaves are in substantial contact one with the other. In forming the bed the leaves are all placed substantially in a face to face, back to back or face to back relationship. In order to achieve the beneiicial results of the method, the bed should be of substantial dimensions, fregrample, not less than feet square. Advantageous Y 21 Y results are achieved if the air is confined' so that it can only flow through the bed and not around the bed.

By way of illustration, the bed can have 100 to 200 leaves of tobacco per square foot. Such a bed permits a wave motion of the leaves as the air passes through the bed. Clusters of three to six leaves are very satisfactory if the leaves are hung on a'string. The butts of such clusters preferably willbe one to three inches apart on each string. Advantageously, the strings will be from about two inches to about four inches apart. p

'I'he conditioned air is introduced to the bed at a tern-k perature within the Vrange of from about 70 F. to'Z00.

F., preferably from 7fO\" F. to 1,307V E. and advantageously,v at F. -to 100 for cigar wrapper 'tabacco'leaves.` This air preferably has a relative humidity of from about 30% to about 75%. In the initial and terminal stagesof curing, the relative humidity may follow the practice of employing a relative humidity of up to In order tol pass the conditioned air through the bed, yit isV maintained ata slight positive pressure. The rateof airv flow through the bed Iwill preferably be from 10 feet perv minute to feet per minute to provide for a tempera-l ture drop in the conditioned air from its entry intoV the. bed to its discharge therefrom of from about Y.1 F. to about 5 F., preferably from about .2 F. tor about 1'- F. The air pressure at the discharge side of the bed will-y be at least slightly lower than the air pressure within thej bed due to the packing of the tobacco.

The tobacco is subjected to the conditioned air for a suicient period of time to cure and dry to the desiredv color, moisture content and quality.

The natural and orderly energy processes of this ourin will be evident, if related to the human body in surface-- conditions, temperature and moisture dissipation. Using wrapper tobacco `for comparison, one green leaf may weight 1% ounces with a total area (both sides) of 200 square inches. Thus fifteen (l5) leaves wil-l equal an average man in supercial area and since 3/10 ounce loss is the maximum permissible per leaf in 24 hours, the rate' of evaporation is less than 10% of that from the human skin, at rest under normal room conditions and far below the perspiration zone. Accordingly, there is no need for the severe conditions of heat and iluctuating wind ventilations used in the normal cures. No swea or discoloration need ever occur with the new moderate temperatures and effective movement factors.

' cate portions. Theseparation of the leaves which is the primary objective of barn curing is entirely avoided. Contact, support, and communication of physical movement between leaves are utilized and thus conduction, and potent inter-radiation (from the external source and evolution from the curing tobacco) are employed, 'in` contrast to upblast on the tips. Furthermore, the gas r; (as from respiration) and vapor diffusion in these def-` inite channels is effective and controllable. The heat, vapor and gas wave fronts pass through the mass, in

'contrast to the erratic convection and diffusion rates.l

caused by vagrant and transient currents from the tight'4 knots of curled tobacco into openA lateral spaces and the; ilues at the ends of the common laths. The sharp chilling.

`,effect of the wet bulb temperature, which'may Well maille*V tain the throttled moist leaf areas below other poritons of the leaf is avoided, as well as what may be termed the Corrosive action of the all too frequently reversible deposit and drying of beads of moisture. Similarly, the whipping and bleaching of tobacco on the outside is eliminated.

The channels established by the stems will create a corresponding directive and proportioning elfect of the internal energy over the leaf, stem and vein surfaces, instead of the stagnant and locked in dampness of the doldrums in the knots created by the usual methods. Actually, these leaves are here maintained under some tension as the shrinkage attempts to take place, with benefit in subsequent operations, s'uch as fermentation and sorting. The at surface of the leaf olers maximum exposure for the functioning of the stomata which are shielded and thus inactive in the usual hanging.

The conditioned air is caused to enter a compact plane of air guiding means, made up of the tobacco leaves and is further distributed under pressure by the delta pattern of stems and veins. The reaction to the air flow pressure causes a smooth wave action, somewhat analogous to a water surface under the inuence of a breeze, since the leaf assembly is free to move and the tips, central sections and butts can move relative to each other. This wave action creates an almost imperceptible opening and closing of air passages, and self-adjustment of the mass of tobacco as a whole. A similar etect operates with the same result when the butt ends are supported on a screen, through which the treating air rises into the angularly placed bed of leaves.

In carrying out the method of this invention, it is preferred to have all of the butts of the leaves either pointing upwardly or downwardly. A highly advantageous control of the llow of conditioned air through the bed of tobacco is achieved when the butts are held in the downward position, advantageously at an angle of from 40 to 80 to the horizontal. In this situation as the leaves proceed through the cure, they Wilt and fall over towards thehorizontal causing a reduction in the ow of conditioned air through the bed.

The method and apparatus in laccordance with this invention will be made more apparent by the following description when read in conjunction with the drawings in which:

FIGURE 1 is a schematic vertical section of curing apparatus in accordance with this invention;

FIGURE 2 is a section taken on the plane indicated by the line 2-2 in FIGURE 1;

FIGURE 3 is a vertical section taken on the plane indicated by theline 3--3 in FIGURE 2;

FIGURE 4 is a vertical schematic section of an alternative apparatus in accordance with this invention.

As shown in FIGURE l, thecuring apparatus 2 in accordance with this invention comprises achamber 4 having mounted therein beams 6, 8 and 10, each of which carries. a series ofhooks 12 for the receipt of a string. A plurality of pairs ofstrings 14, each carrying a series of hands of tobacco leaves 16 in closely strung relationship are secured tohooks 12 to form abed 18 of tobacco leaves, the butts extending upwardly. Each hand of tobacco, as shown, comprises four leaves. The Stringing up of the tobacco can be accomplished in any convenient manner as, for example, that shown in my Patent 2,682,- 341, issued June 29, 1954. All of theleaves 16 are substantially face to face, back to back or back to face and the pairs ofstrings 14 are spaced sutliciently closely together so that the leaves of adjacent pairs will be in contact.

Conditioned air is supplied by air conditioning apparatus indicated schematically at 20. Any conventional air conditioning apparatus can be employed, for example, thev apparatus shown in my Patent 2,479,526, issued August 16, 1949. The conditioned air passes fromapparatus 20 toconduit 22, toconduit 23 and thence to branchconduits 24. Eachconduit 24 is provided with downwardly directedtubes 2,6 havingtins 27 angularly disposed to distribute the air laterally of theconduits 24.

If desired, a slight negative pressure is maintained on the tip side of thebed 18 by means of an exhaust blower schematically indicated at 28 and connected tocompartment 4 as shown at 30. If it is desired to cut theexhaust blower 28 olf fromcompartment 4, this can be accomplished by adoor 32 held by a holdinglatch 34. If it is desired to recirculate air toair conditioning apparatus 20, this can be accomplished by openingdoor 36 which can be held open by a latch schematically indicated at 38.

Analternative curing apparatus 40 is shown in FIG-URE 4.Apparatus 40 is provided with achamber 42 in which are secured a pair oftransverse beams 44 and 46.Screen 48 is secured to the upper side ofbeams 44 and 46 respectively. A bed of tobacco S2 is formed by stacking tobacco leaves 54 onscreen 48 with thebutts 56 resting on the screen.

Conditioned air is supplied under pressure at the butt side of thetobacco bed 52 by air conditioning apparatus indicated schematically at 58 provided with anair inlet conduit 59 and which is connected to aconduit 60.Conduit 60 hasdischarge ducts 61 provided withfins 63 to distribute the air laterally ofconduit 60. Air is returned toair conditioning apparatus 58 fromchamber 42 byconduit 62 controlled byvalve 64. A negative pressure may be maintained on the tip side of thebed 52 by means of a blower indicated schematically at 66. Avalve 68 controls the ilow of air fromchamber 42 toblower 62.

It is not desired to be limited except as set forth in the following claims,

What is claimed is:

1. The method of curing tobacco leaves which comprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by securing the butt ends ofl the leaves to a support with the leaves extending' in one direction at a substantial angle to the horizontal, and forcing air through the leaves of the bed, said air being introduced into the bed at a temperature of from about 70 F. to about 200 F. and said air being forced through the leaves until the desired color and moisture content are achieved.

2. The method of curing tobacco leaves which comprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by securing the butt ends of the leaves to a support with the leaves all extending in one direction at a substantial angle to the horizontal, and forcing air through the leaves of the bed to provide for a temperature drop in the air from its entry into the bed to its discharge therefrom of from about .1 F. to about 5 F., said air being introduced to the bed at a temperature of from about 70 F. to about 200 F. and said air being forced through the leaves until the desired color and moisture content are achieved.

3. The method of curing tobacco leaves whichV comprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by securing the butt ends of the leaves to a support with the leaves all extending in one direction at a substantial angle to the horizontal, and forcing air through the leaves of the bed, said air being introduced to the bed at a temperature of from about 70 F. to about 200 F. and having a relative humidity of about 30% to about 75% and said air being forced through the leaves until the desired color and moisture content are achieved.

4. The method of curing tobacco leaves which oomprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by securing the butt ends of the leaves to a support with the leaves all extending in one direction at a substantial angle to the horizontal, and forcing air through said bed to provide for a temperature drop in the conditioned air from its entry into 'the' bed to its discharge therefrom of from about .1 F. to

about 5 F., said air being introduced to the bed at a temperature of from about 70 F. to about 200 F. and having a relative humidity of about 30% to about 75%, and said air being forced through the leaves until the desired color and moisture content are achieved.

5. The method of curling tobacco leaves which comprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by securing the butt ends of the leaves to a screen butt down with the leaves all extending in one direction at a substantial angle to the horizontal, and forcing air through the leaves of the bed, said air being introduced into the bed at a temperature or from about 70 F. to about 200 F., and said air being forced through the leaves until the desired color and moisture content are achieved.

6. The method of curing tobacco leaves which comprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by securing the butt ends of the leaves to a support with the leaves all extending in one direction at a substantial angle to the horizontal, forcing air through the leaves of the bed, said air being introduced into the bed at a temperature of from about 70 F. to about 200 F., and exerting a negative pressure on the side of the bed opposite the side at which the air is introduced to the bed, said air being forced through the leaves until the desired color and moisture content are achieved.

7. The method of curing tobacco leaves which comprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by Stringing the butt ends of the leaves to strings with the leaves all hanging downwardly, and forcing air through the leaves of the bed, said air being introduced into the bed at a temperature of from about 70 F. to about 200 F. and said air being forced through the leaves until the desired color and moisture content are achieved.

8. The method of curing tobacco leaves which comprises: forming a bed of tobacco leaves with adjacent leaves in substantial contact by Stringing the butt ends of the leaves to strings with the leaves all hanging downwardly, and forcing air through said bed to provide for a temperature drop in the conditioned air from its entry into the bed to its discharge therefrom of `from about .1 F. to about 5 F., said air being introduced to the bed at a temperature of from about 70 F. to about 200 F. and hav- Ving a relative humidity of about to about 75% and said air being forced through the leaves until the desired color and moisture content are achieved.

References Cited in the le of this patent UNITED STATES PATENTS 1,543,245 Busenoid June 23, 1925 2,086,194 Smith July 6, 1937 2,475,568 Moore July 5, 1949 2,714,385 Jackson Aug. 2, 1955V 2,882,911 Pinkham Apr. 2l, 1959

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