US2343345A - Method of curing green tobacco - Google Patents

Description

March 7, 1944. R. D. TOUTON METHOD oF CURING GREEN' lToAcco 3 sheets-sheet 1 Filed Dec. 1l, 1940 r rmrrr fd WEA/raf? /zPas/ 73u for:

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METHOD OF CURING GREEN TOBACCO Filed Dec. l1, 1940 3 Sheets-Sheet 2 RAD/A raf? V Mum/fas.' @Wr/M( March 7, 1944. n R. D, TQUTON 2,343,345

METHOD Of CURING GREEN TOBACCO Filed Deo. l1, 1940 3 Sheets-Sheet 3 Patented Mar. 7, 1944 METHOD OF CURING GREEN TOBACCO Rush D. Tonton, Cynwyd, Pa., assignor to Wurton Machine Company, Philadelphia, Pa., a corporation cf Pennsylvania Application December 11, 1940, Serial No. 369,652

(Cl. ISL-140) 17 Claims.

This invention relates to a method for curing green tobacco and more particularly relates to a method adapted for the curing of green tobacco in the eld following its harvesting. The apparatus disclosed herein for use in performing said method is also disclosed in my copending application #369,653 filed Dec. 11, 1940.

As is well known, green tobacco leaves after harvesting have heretofore been strung closely inl pairs and hung in banks in a dense mass for curing in so-called sheds, having a tight roof and walls formed by louvers capable of adjustment for various openings.

The curing of the green tobacco leaves in the sheds requires about days, more or less, 'and it has been sought to obtain desired atmospheric conditions; i. e., temperature and moisture content, within the sheds by various adjustment of the louvers and the burning of charcoal pots within the sheds with respect to the prevailing temperature and moisture content of the outside atmosphere, the wind velocity and its direction with respect to the sheds.

However, it has been found that the closeness or dense packing of the leaves as they are hung in the shed results in unsatisfactory curing of the leaves near the walls of the shed and insulation of the inner leaves toward the center of the shed so that they do not receive proper treatment. This insulation of the inner leaves is particularly objectionable while the leaves are still green, starchy and distended to their full face area and at the same time contain a maximum water content.

It has also been found that non-uniformity in the curing of the tobacco in any given shed arises from the fact that curing of the tobacco in the upper part of the shed, which is placed iirst, starts and often proceeds substantially before curing of the tobacco in the lower part of the shed, placed last, starts.

Further, under present practice and with present equipment it is extremely dicult, if not impossible, to maintain the necessary conditions for good curing during the latter stages of the operation, as for instance, after the sixth to seventh day, due to the shrinking of the leaves which permits too great a circulation of dry air, together. with the fact that the leaves no longer contain suiiicient moisture to create the necessary relative humidity.

The present procedure, essentially dependent upon general atmospheric conditions, of necessity is lacking in any uniform control of the conditions under which the tobacco is cured,

makes no allowance for the different characteristics of different parts of the tobacco leaf and frequently results in the production of tobacco of low quality, from the standpoint of texture, color and taste, and consequently of a value considerably less than could be expected from the nature of the green tobacco when harvested.

A careful study of the nature of the green tobacco leaf and of the requirements of proper curing shows that the butt and stem portions of the leaf are relatively coarse and sappy and contain a relatively large amount of moisture, while the median portion, containing less moisture than the butt and stem, contains substantially more moisture and is coarser than the relatively fragile tip portion. Furthermore, the maximum width of the leaves occurs in this median portion setting up an overlapping condition with a resultant impedance of circulation when the leaves are placed in the curing shed.

In the curing of the green tobacco leaf, it is the object to remove the moisture, to the desired extent, and bring the leaf to desired color, while, at the same time, retaining its texture. In general, it is usual to support in the average shed about 40,000 pounds of green tobacco leaves, of

which weight some is moisture. In the curing, the tobacco leaves are brought down to a weight of about 10,000 pounds, of which some 20% is moisture. In the curing the major moisture loss occurs in the rst five to six days and care must be exercised, especially between the second and sixth days, to avoid rotting or pole sweat which is most likely to occur in the median portion of the leaf, when the leaf has partially wilted and part of the leaf cells are dead, but the leaf still contains from 50% to 70% moisture, which promotes the growth of pole sweat spores in the dead cells.

In the prior practice indicated above, as will be obvious, the tobacco leaves were essentially subjected to atmospheric air, the humidity, temperature and flow of which was subjected to variation with the physical condition of the leaves, time of day or night and local meteorological conditions under such control only as could be exercised by adjustment oi the louvers forming the sides of sheds and the burning of charcoal potswithin the sheds; and, again, the dense packing o'f the leaves prevented any approach to uniform circulation through the mass of tobacco. Also, the necessity for wide open louvers to admit suicient air for anything like circulation in the center of the mass often causes wind damage on the leaves near the outside of the shed near the open louvers ny event, subjects the outside leeres to ov; r"tic treatment in cornparison with that by the inside leaves.

As a result of the noir-uniform condition of the atmospheric air available to the shed and the inecient control thereof, especially ol the volume and of its flow with respect to the tobacco leaves and the different parts thereof, wide variation the conditions occurred locally within the shed from the effect of the rying tobacco upon the air.

Now in accordance with this invention there is provided a highly ecient and economical methor for the curing of green tobacco, and by the practice and use of which the curing ofn green tobacco in the usual shed is enabled and production of tobacco of high quality is assured.

Generally speaking, in accordance with this invention green tobacco leaves o-r plants are strung and hung in close relation as heretofore conventionalA in a curing shed of the usual type having louvers in its walls and modified only by provision for ventilation through the roof. Uniformly conditioned air or atmospheric air tempered with conditioned air to a uniform condition is introduced to the tobacco in controlled volume and directionr of ilowfwith respect to the leaves and also with respect to outside conditions, such as temperature and humidity andk wind direction and velocity, so that the different parts of the leaves are subjected to air at a condition and in circulation best suited to their curing at a proper rate, with uniformity, with avoidance of rotting and with retention of texture and ilavor and acquisitionof desired color.

More specifically the conditioned air is introduced centrally of the mass of tobacco and cir-V culated outwardly and downwardly therethrough. The airis variously introduced in quantity to create a positive pressure withinV the shed and is introduced variously in greater quantity in the lower-part of, the shed than in the upper part and vice versa. Again, stackl effect in the shed by virtue ofY ventilation through thek roof, which may be enhanced by the introduction of air selectively into the lower part of the shed, or by heat from the surface of ducts through which warm air is introduced, isused to promote uniformity. Again, downdrafteect may be obtained, causing an inilow; of air through the ventilator desirable for the introduction of cool, normal night air to tobacco` in the upper part ofthe shed by the introduction, of' cool air selectively in the upper part or the shed, or from the effect of the cool surface of ducts through which cool air is introduced intothe shed.

The circulation rate will vary from one complete change in ten minutes downward to one change in forty minutes. Furthermore, during the later stages of curing, for instance, after the fourth or fifth day, a greater quantity of air :may be admittedat the bottom of the shed than at the top while utilizing stack eiect. Again, intermittent operation orf the circulating system may be desirable, asfor instance, for a total period of not over lzhours in each 24. This may bei arranged for sixV hours circulation during the day' and six at night with the night operation being particularly? important during the early morning hours when the temperature of the ground, shed and tobacco has been lowered to the dew point of the outsider air, thus causingy condensationV on the tobacco.

In addition, moisture from conditioning equipmentvmay be added to the atmospheric moisture as at night to provide the essential factor in curing known as come and go. That is, the conditioning system will be used in conjunction with the outside air. Generally, the conditioner will be so arranged that it will add not more than 30% relative humidity to the air being crculated and if used for heating or cooling the temperature increase or decrease over the outside air or that in the shed will be not over 15 F. These restricted increments will effectively prevent severe treatment of leaves next to the outlets as compared to the present system where harsh conditions are imposed upon the tobacco near the outside walls and in the lower tiers directly over the charcoal reswhen such are used.

They conditioning system will be arranged so that during periods of maximum heat requirementk as when the shed is initially loaded with cold,A wet tobacco, additional outlets in the bottoms of the down draft ducts will automatically open, thus providing the greater amount, of air necessary to carry the required number of heat` units without a detrimental increase in the amount necessary in each unit of` circulating air.

Also, the central portion heretofore insulated from the proper heating effect and in a stagnant air condition will receive an adequate circulation of conditioned air.

Furthermore, the air flow may be directed.

against the prevailing wind to establish further uniformity within the structure and the outlets will be arranged for rotation so that they may be variously directed under Acertain conditions to avoid any constant severe treatment of leaves nexttothe openings.

Thisy application of conditioned air will be accomplished with much economy, permitting the use of 'a standard curing shed structure since the conditioning efect is applied in the center ofthe mass desirablyto create a positive pressure within the; shed, and in passing` outwardr through the leaves permits maximum service before its eilect is dissipated.

Having now indicated in a general way` the nature and purpose of the method according to this invention, it is believed that it will beunderstood in detailzfrom thefollowing description of a form of apparatus-adapted for use in carrying out the method, with referencey to the accompanying drawings in which:

Figure i is a plan view showing an embodiment of apparatus adapted for carrying out the method in accordance with this invention.

Figure 2 is a diagrammatic sectional view of apparatus adapted for carrying out the method in accordance with this inventiom taken adjacent a point of introduction of conditioned air into the mass of tobacco.

Figure 3v is a cross-,sectional View showing details or the air conditioning instrumentalities included in. the apparatus shown in Figures l andv 2.

Figure 'i is a detailed view, partly in section,

showingthe instrumentalities included in the a t for paratus in association with the wall of a tobacco curing shed.

Figure 8 is a side view of the air conditioning apparatus shown in Figure 7.

Figure 9 is a side View of a. string of tobacco leaves as hung in a tobacco curing shed.

Figure 10 is a sectional view on line lil-I5, Figure 6.

Figure 1l is a view, partly in section, showing a detail of construction.

Referring initially more particularly to Figure 9, I6 indicates a string upon which. are threaded or strung a series of green tobacco leaves 7'.- The string I6 passes through the butts of the leaves and the leaves, as is customary, are strung in pairs I'I, the leaves of the pairs facing oppositely. In similar manner stalks may be hung. The string I5 is secured at its ends to a stick 7c adapted to be supported in the shed on rack members I8.

The tobacco leaves i are divided into three essential portions, as illustrated in Figure 9,

namely, the butt portion I9, the median portion 20 and the tip portion 2i.

Referring now more particularly to Figures 1 5, A indicates a tobacco shed, which may be of any desired size and construction7 and desirably will have louvers a. in its walls. The shed will be located in any convenient position to the tobacco fields. A ventilator or series of ventilators 62, controlled by a damper S3, are provided in the roof of the shed to afford a stack eiect where desired.

B` indicates a tractor or any ordinary or desired type. The tractor may be and desirably will be such tractor as may be used in connection with the growing of tobacco to be ultimately cured in the shed A.

C is a trailer unit adapted to be coupled to and drawn from place to pla-ce by the tractor B. Upon the trailer unit is an air conditioning apparatus or instrumentalities for the conditioning of air.

Within the lower part of the shed A and eX- tending longitudinally of the center thereof is an air duct E, provided on its upper side with a series of upwardly directed nozzles f. The nozzles f are extended from end to end of the duct E and are spaced suiliciently close so that streams of air g issuing from the nozzles will blend and travel upwardly and outwardly within the shed, in and from a free zone mil between or centrally of the banks of tobacco leaves, as will appear. Beneath the ridge of the roof of the shed A and extending in a line above the nozzles f in duct E is a curved baiile li, divided centrally by a verticalv member i. The member i is directly in line with the nozzles f and adapted to divide air traveling in zone 493 therefrom when it reaches the baffle.

As will be obvious from an inspection of Figure 2, the blended streams of air g from the nozzles f passing upwardly within the shed A, in a zone lill) extending vertically of the mass of tobacco supported on stacks ic in which the air is desirably at a positive pressure, will extend outwardly into the mass of tobacco and such as reaches the baffle li will be divided by the member i and directed oppositely downwardly by the curved bafiie h so that a downward circulation of air will be set up within the shed, as indicated by the arrows Figure 2. By virtue of the direction of the'circuiation the air directed downwardly will iirst pass downwardly along the butts of the leaves and then along the median portions and then along the tip portions.

Leading from the duct E, a lateral duct M aligns with an opening n in the side of the shed. Adjacent the opening n with which the duct M communicates is an opening o in the side of the shed.

The air conditioning instrumentalities mounted upon the trailer C comprised, as shown in Figure 3, an intake duct p adapted to be aligned with the opening o in the side of the shed and provided with a flange q adapted to bear against the side of the shed and make a tight connection and a discharge duct 7', adapted to connect with i the opening n in the side of the shed with which the lateral duct M extending from the duct E communicates. The end of the discharge duct is provided with a ange s (Fig. 4) adapted to bear against the side of the shed and make a tight connection. The intake duct p is provided with an opening to the atmosphere t, controlled by means of a swinging closure u.

Within the intake duct is a coil v, the ends of which are adapted to be connected with thv:r

water jacket of the tractor engine w through the medium of flexible pipes or hose rc, 1: connected to nipples y, y, let into the walls of the water jacket and provided with valves e, e. A pump I, is provided for effecting circulation of water from the tractor engine Water jacket through the coil y, with return to the water jacket.

Within the discharge duct is a pan 2 containing a coil 3 and adapted to contain water to a level 4 to cover the coil 3. The coil 3 is connected at one end through a exible pipe 5 to a nipple 6, which extends from the exhaust manifold 'l of the tractor engine and is provided with a valve 8. The other end of the coil 3 leads to atmosphere, or preferably into a pit (not shown) adapted to absorb exhaust gases. The end of the coil connected to nipple 6 is provided with a valve I5 adapted to throttle and control the amount of exhaust gases passing from the engine manifold 'I into the coil.

As will be obvious, when exhaust gases are permitted to circulate through the coil 3, which is beneath the water level 4 of the water in the pan 2, water will be evaporated into the air passing through the discharge duct and over the pan.

A fan 9 is provided in the discharge duct adjacent its juncture with the lateral M within the shed. The fan is adapted to be driven from the power take-olf I0 of the tractor through the medium of a belt II. The fan is arranged to operate to draw air from within the shed into the intake duct in heat interchange relation with coil v, then over the pan 2 and discharge it into the lateral M, through which it passes to conduit E, from which it passes into the shed, as

fjdescribed above, through the nozzles f. The fan also serves to draw into the intake conduit fresh air through the fresh air opening t. The fan 9 may be reversed to reverse the direction of oirculation which may variously be desirable.

Within the shed is positioned a thermostat I2. which operates to control the circulation of heating fluid through the coil o through control of the operation of the pump l. The control of the pump Z by the thermostat may be of any suitable or well known type, the control connections being indicated by the line I3.

A humidostat I4 is positioned within the shed and operates to control the circulation of exhaust gas through the coil 3 by control of the valve I5. The humidostat may effect control of the valve, {.5- by any known or desired means, the

connection between the humidostat and the valvebeingindicated by the line it.

Theoperation of the apparatus described above furthe. treatment of tobacco will, it is believed, be obvious. However, it will be noted that the humidostat and thermostat within the shed will: be set for the conditions desired for the curing of leaves of green tobacco y' hung in banks on opposite sides of the free zone itil within the shed. The tractor and air conditioning apparatus upon the trailer having been connected together as described above and the intake and eX- haust conduits of the conditioning apparatus having been moved into engagement with the sideof the shed in alignment with the openings therein, the tractor engine will be started. In operation of the tractor engine, the fan 9 will be rotated and circulation of air into, within and out of the shed will be set up. The fan will be operated to deliver such quantity of air as to set up a positive pressure within the shed, which may be readily accomplished due to introduction of the air in a `zone centrally of the mass of tobacco, which will act to baille the passage of the air to the sides of the shed. The circulation within the shed will be such as described and as shown by Figure 2. The closure u for the fresh air opening t will be adjusted, as will the louvers a to admit atmospheric air. The adjustment of the louvers and of the closure u will depend upon the condition of the atmospheric air with respect to the condition desired in the shed and the direction or the wind. Variously during the cur-` ing period the louvers a may be entirely closed and variously when the curing has progressed the air conditioning.apparatus may be shut down and. thecuring allowed to proceed under atmospheric air admitted through the louvers. rlhe air passing outwardly and downwardlyvbetween the banks of leaves will be deflected downwardly within the mass of leaves by thev leaves as it progressesv outwardly.

Hot water from the water jacket of the tractor engine. will be circulated through the coil c, for

adjustment of the temperature of the air withdrawn fromv the shed together with the fresh air added thereto, by means of the pump Z. The amountof circulation with reference to the heat of the water will becontrolled by the thermostat i2, sov that the air willy be brought to the desired temperature. As desired, hot exhaust gas from theA exhaust manifold of the tractor engine will be circulated through thev coil 3 for the evaporation. of water from( pan 2. The amount of gas passed through the coil 3- for the evaporation of such an amount of water from the pan 2 to bring ther air to the desired relative humidity will be controlled by the valve l5, under control of the. humidostat i4.

Asv will be obvious, the air at desired relative humidity and temperature willthen be returned to the shed forl curingif the louvers a be closed or if they be open more orV less to temper the atmospheric air entering through the louversfor the maintenance of desired conditions within the shed. Generally the outer portion of the mass of tobaccowill act to baille or hold the conditioned. air within the mass.

In many, iifnot all, instances, it will be desirable variously to utilize` the stack effectv aiorded by the ventilators Thus, when the charging of the shedwith tobacco is. completed, it will usually` be found that air heated by the sun on the roof. has accumulated in the upper part of 'the shed and that the tobacco therein hasrstartedto.

with the tobacco in the upper. part of they shed,`

to the end that all the tobacco will beuniformly cured in the subsequent treatment involving use of the conditioning apparatus and tion of air to create a positive` pressure within the shed. Air under positive `pressure within the shed may also be used variously during any stage of the curing when it is desired to heighten the stach eiiect. Such may be accomplished by the introduction of atmospheric air into the shed through nozzles f in the preliminary stage, or conditioned air vhen the stach eiect is used in a subsequent stage of the curing.

Referring now more particularly to Figures 6 8, which illustrate certain modifications of the showing ci Figures 1 5 and in which similar parts to those shown in Figures l-5 are indicated by similar symbols, within the upper part ofA the shed extending longitudinally thereof beheath tl? ridge oi the roof is a duct ll from which extend downwardly, at short intervals in a zone extending vertically within the mass of tobacco supported cn sticks 7c, vertical ducts 22 provided at intervals with lateral, slightly downwardly extending nous es and with dampers 6l proportioned to pass some air, say about 30%l when closed. The nozzles 23 on one side ci the vertical ducts are desirably larger than those on the other side, as shown. in Figure lil. l'helo-wer ends oi the ducts are closed by spring held flapper valves i543.

The vertical ducts extend downwardly inv the free Zone itil between the banks of tobacco and are rotatably supported from the duct as for example, through the medium of ball bearings (Figure il) and each of the ducts is connected to a wind vane 5i, supported on the shed roof, through a 1:1 searing and a shaft 53 to which the wind vane is secured. Thus, the ducts 22 may be rotated, when there is sufficient wind force operating on the vane 5l, to various positions dependent upon the wind directions. The wind vane il will be arranged so that the larger openings 3 will open against the wind.

Within each oi" the ducts is arranged a spiral ange lit (Figure ll) which, on the passage of sufficient air flow down the ducts 22, will cause the ducts to be rotated when the wind velocity is inconsequential and as a consequence the vane 5i does not exert a directing eirect upon the openings in the duct The duct E' is connected intermediate its ends with the discharge of the fan S by a duct M. The nozzles 23 are spaced so as to' project air from the ducts 32 in zone iii-il between the banks of tobacco over and downwardly upon the butts of the leaves of tobacco j, j hanging from the sticks k, a downward circulation of the air through the tobacco leaves from the butts to their tips, as indicate the arrows Figure 6, being promoted by fan which draws air from the lower part of the shed through outlet opening o. The air in effect circulates downward in a plurality of layers or blankets so that the greatest amount of air is moving downward in the lower part of the shed. The air is. desirably introduced in amount the introducto create la positive pressure within the shed, which is made possible by insulating effect of the banks of tobacco.

Within the shed may be placed charcoal pots 24, or other heating elements, which may be used when for any time in the curing of the tobacco a temperature higher than that obtainable with the air conditioning apparatus is desired and which, if burning, will increase the stack effect resultant from the opening of ventilators 52 when such is desired.

If desired, an auxiliary heating element til may be arranged within the intake duct p and may be controlled by thermostat I2.

In the air intake duct p of the conditioning apparatus, ahead of the heating coil v is a water spray head 25. The spray head 25 faces against the oW of air and is supplied with water by means of a pump 26 connected to draw water, heated as desired, from pan 2. The air passing through the intake duct p receives water sprayed from the spray head 25 and on being heated in its'passage through coil v takes up a major portion of the water, any free water being thrown out of the air and returned'to pan 2 as the air strikes the curved end of duct p in its passage to the discharge duct r.

In the discharge duct'r adjacent to its point of discharge into the casing of the fan 9 is placed a second water spray head 27 which, facing in the direction of the ow of air from duct 1' into the fan casing, discharges a spray of water into the fan casing for admixture vwith the air by the blades of the fan in the presence of the heat put into the air by the fan. The spray head 2'1 is supplied with water by a pump 2S which is arranged to draw water from the pan 2. A conduit 29 leads from the bottom of the ian casing to the pan 2 for the return of Water not taken up by the air in the fan casing.

A diierential thermostat 3S is placed to operate on the difference between the temperature of the air entering the shed and that withdrawn and is connected by any suitable means 3l to control the throttle of the tractor engine W. The control by the thermostat will be such that when the temperature of the air withdrawn from the shed drops', the engine Will be speeded up, causf ing the fan to be speeded up, supplying more circulation and heat to the coil '12 for heating the air in the conditioning apparatus. Thus, the thermostat 3U exercises control of the volumeand `temperature of the air circulated in the shed.

Conversely, when'humidiiying without heating a differential humidostat 3W operates to control the amount of moisture supplied to the shed by eiectin'g an lincrease or decrease in the rate of circulation through connection 3l' to the engine throttle.

In the operation of the modiiied form of apparatus shown in Figures 68, the procedure will lbe essentially the same as that described in connection with the 'use of the apparatus shown in Figures 1-5. However, it will be noted by virtue of the arrangement of the air discharge nozzle 23, which discharges from the duct 22, `conditioned yairis supplied rst to the butts and stems of the nozzles 23 being properly conditioned for treatment of the butts of the leaves becomes, by virtue of moisture absorbed from the butts and the cooling effect of the loss of moisture from the butts, proper for treatment of the median portion, and in turn for the tip portions. The downward circulation in which the air flows from butt to tip of the leaves insures that the air reaches the median portion of the leaves between the leaves which -tend to be shielded from an upward flow of air by the form of the leaves as they are strung in pairs and by the relatively greater breadth of this median portion. Hence, rot which occurs on the shielded median portion is avoided.

By virtue of the directing effect of the wind ,vane 5|, if there be a Wind of substantial velocity forcing air into the shed through the side walls, the ducts 22 will be positioned by the Wind vane with the larger of the openings 23 discharging into the wind. Hence, the effect of excessive wind velocity will be negatived by the larger volume of air discharged against the wind as compared to with it. If the Wind velocity be incon- .sequential the ducts 22 may be caused to rotate for average uniform delivery of air to the tobacco by the action of the downiiowing air on the special iianges 54 in the ducts 22.

The introduction of Water into the air in the conditioning apparatus through spray head 25 and the introduction of a spray of water into the fan casing insures the proper humidication of the air in conjunction with the water supplied to the air by vaporization from tank 2.

When the shed is initially loaded with cold, relatively wet tobacco and higher than average heat is required, suiiicient air is delivered to ducts 22 to cause the valves 60 at their lower ends to open, thus permitting the delivery of an increased quantity of air into the shed.

It will be noted that the temperature of the air circulated through the shed will be fixed by the heat supplied to the air in passing over coil v and also by the heat put into the air in its circulation, as by the Work done by the fan, friction in the clucts, etc., and by heating element 40, if desire As more specifically illustrative of procedure according to the method of this invention for the curing of green tobacco with the use of apparatus herein described and the operation of which has been herein described in a general way, for example, it may be assumed that the shed A has been fully charged with green tobacco.

When the shed is fully charged with tobacco, it 'will be round generally that curing of the tobacco 1n the upper part has commenced, While the tobacco in the lower part of the shed has not commenced to cure. This situation arises from the fact that the tobacco is charged into the upper part oi' the shed rirst, and due to the fact that the air in the upper part or the shed is hotter than that in the lower part of the shed due variously to the heating effect of the sun on the roof.

Hence, in general, it will be desirable initially to open damper 63 and permit a stack effect upon the interior of the shed through the ventilator 62, while introducing air into the lower part oi' the shed to increase the stack effect. If the air .introduced is warm, radiation from the surface of duct E will increase the stack eect.

The introduction of the air into the lower part of the shed in combination with the stack elect through the ventilator 62 will tend to hold the condition of, or slow down the curing process of the tobacco in the upper part of the shed, while the tobacco in the lower partof the shed is being brought into condition `comparable with that of the tobacco in the upper part 'of the shed.

When using the apparatus shown, for example, in Figure 2, an amount of air will be introduced 5 into the lower part of the shed through the nozzles and in such condition vas to primarilyaiect the tobacco in the lower part 'of the shed. When using the apparatus as shown in Figure 6 the damper iii in the vertical conduit 23 will be opened Yso that the major portion of the air will pass down the conduit fordischarge through'the nozzles 23 Yin the 'lower part of the shed.

The mass of tobacco as a whole in 'the shed having been brought to 'a r'substantialiy uniform state of curing, air wiii be `introduced through the nozzles f, Figure 2 or through the nozzles 2.5i, Figure 6, in the latter cese with lthe iii adjusted for uniform discharge 'of air. The air will, of course, be conditioned as has 'been indicated to promote the Ydesired curing of "the tebacco. 'During the curing, 'andespecially'diiring the second to sixth days, when part 'of the -leaf cells are dead and part are still throwing "off moisture, the updraft 'stack effect 'vviil 'be desirably used to carry off the evaporating 'moisture to avoid the formatio'n'of bea-ds of sweat''n the leaves with consequent promotion of attack by fungus.

During the treatment the 'louvers a 'will be opened to lcreate a circulation of atmospheric air to the extent indicated by conditions within the shed and by the precise condition to be maintained within the shed.

A lpositive lpressure Within the 'shed will be readily obtained by virtueof the insulating effect i the banks of tobacco on'opposite 'sides of the shed. By virtue ofthe positive pressure within the shed the "air will flow outwardly from VZone lh? as well Yas downwardly with respect "to "the tobacco -in the 'banks 'and 'the leaves the interior and throughout themass wiil "thus besubjected to substantially 4uniform treatment.

Since the tobacco `in the upperlpartof theblied will tend variously to lose `a greater amount 'of moisture than will the tobacco in the lou/.jr pa'rt of the shed, it may,'and usually wiil, bedesirable on the iifth or ysixth -day of treatment to intro"- duce `a greater lquantity of air "having an in'- oreased moisture content 'into'the upper parte'c the shed than Ainto the lower part 'of the s by adjustment ofthe damper '6i in the vertical conduit 22. Under such condition the'dam'per 6:5 and ventilator e2 maybe uclosedor adjusted to give more or less stasi; eiiect and,'depending upon conditions, the llouvers u' may be-ciosedor more or less opened. variously the tobacco 'in the upper part of the shed may lose moisture more rapidly than that in 'the iower part" due tothe effect oi" the suns -heat `on the shed roof. In such case cool, moist evening air maybe intro-duced into the upper part of the 'shed through theventilator by causing-a dovvndraftbyselecu tively discharging cool, -moist air 'into the upper part of the shed and by the 'coolingefect of duct E and ducts 272, through which the Vcool air is introduced. l

It will be yappreciated that stack effect`obtained by use of the ventilator iiand the int duction of air in varying amount in the 'upper or lower portion of the liree zone iiiiiythe creation of a positive pressure within the shed, the use of the louvers `aand of the conditioningl apparatus for the-air supplied "from zone VHit 'will enable the mass of tobacco within theshed'to'b'e f;

subjected to substantially uniform ideal condii tions for its curing, with avoidance of pole sweating and other negative eiects on its color, texture and davor, and with reference vto the curing process as a whole. it will also be appreciated that by virtue of vertical draft up or down provided for, atmospheric air will be introduced into the shed, since the ventilator and louvers will be of suiiifient size, to supplement the air from the conditioning apparatus, thus enabling good curing to be obtained with the use of a minimum of power and equipment.

The advantage of the method in accordance with this invention will, it is believed, be apparent. The apparatus, exempliiied for Carrying out the method, is of the greatest simpieit-y and for its operation and transportation from place to place requires only an ordinary farm tractor and the curing of green tobacco is enabled with accuracy of control with consideration for the changing condition of the tobacco in the course of curing and changes in the condition of outside atmosphere and of wind direction and 'velocity. At the same time, favorable atmospheric conditions are utilized in the usual Way when they exist.

lt will be understood that the method above disclosed and variously the details thereof are not limited in their application to the drying of tobacco, but variously are adapted for application to the moistening of tobacco, in which application they variously are of advantage.

It will be appreciated that it is not intended to limit this invention by the above detailed description given for illustrative purposes, since, c

as will be obvious, various modification in detail may be made without departing from the scope of the invention.

This application is a continuation-impart of the application led by ine Serial No.274,133, viled May l?, 1939, which application became abandoned December l2, 194i).y

What I claim Yand desire to protect -by Letters Patentis: n

1. The method of curing green tobacco leaves after harvesting which comprises supporting Ygreen tobacco lleaves vin superimposed banks, `op- .posite ends of the banks being exposed to V'atmospheric air and adjacent endsof the banks being separated to form a free zone and causing conditioned air from said free Zone at a posi- Vtive pressure therein to ow laterally Youtwardly ninto the banks of tobacco leaves whereby `thetovbacco'leaves in the opposite end portions ofthe banks will be'cured by atmospheric air `and the tobacco Yleaves in the ra'djacentjend 'portions of the banks will beoured by conditionedair.

2. The method of curing green tobacco vleen/es after harvesting which comprises supporting the green tobacco leaves'in a mass in a pendent position ina chamber, setting up a v`ciowoioonditioned air fromwithin the mass of tobaccd'latverally and downwardly 'over'thetobacod "from butt to tip of the leaves, withdrawingair from nsaid chambcryconditioning the air with respect to temperature andy humidity and' returning git" to said chamber for reflow therein 'and eiecting the admission of atmospheric air atthesidesof themass. Y Y

3. The method of curingg'reen tobacco leaves after'harvesting which comprises supportinghe "green tobacco leaves in' a chamben'inbanksih 'a mass in a pendentfposition, iiowin'g"`conditined fair from within the mass, at *a vr{ io'sitive "preslsure, outwardly and downwardly between "the banks of leaves, admitting atmospheric air to the chamber through a pair of opposite walls thereof and flowing conditioned air into the lower part of the chamber beneath the banks of leaves.

4. The method of curing green tobacco leaves after harvesting which comprises supporting the green tobacco leaves in a chamber in banks in a mass and in a pendent position and projecting streams of conditioned air of alternately varying volume laterally and downwardly between the banks of leaves.

5. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a mass in a pendent position in a chamber and introducing air under pressure laterally only into that portion of the mass of tobacco leaves which is supported in the lower part of the chamber and at the same time withdrawing air from the lower part of the chamber with stratication in the lower part of the chamber of air introduced into the lower part of the chamber.

6. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a mass in a pendent position in a chamber having an opening to the atmosphere in one of its walls, introducing conditioned air under pressure to the tobacco laterally only from a zone extending vertically within the mass of tobacco leaves and permitting exhaust of air from the top of the chamber, whereby the conditioned air introduced into the chamber will be supplemented by atmospheric air from without the chamber.

7. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a mass in a pendent position in a chamber, introducing air from a zone within the mass laterally into that portion of the mass of tobacco leaves which is supported in the upper part of the chamber and at the same time withdrawing air from the upper part of the chamber with stratification in the upper part of the chamber of air introduced into the upper part of the chamber.

3. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a mass in a pendent position in a chamber, introducing cool air from a zone within the mass laterally into that portion of the mass of tobacco leaves which is supported in the upper part of the chamber only and at the same time withdrawing air from the upper part of the chamber with stratification in the upper part of the chamber of air introduced into the upper part of the chamber.

9. The method of curing green tobacco leaves after harvesting which comprises supporting the green tobacco leaves in a chamber, in banks in a mass in a pendent position and flowing conditioned air from the center of the mass outwardly and downwardly between the banks of leaves while admitting atmospheric air to the chamber through a pair of opposite walls thereof, thei stantially uniform state of curing, then introducing air into the mass of tobacco laterally from a zone extending vertically within the mass of tobacco to effect its curing.

11. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a mass in a pendent position in a chamber, introducing air into the lower part of the chamber only and affording escape for air from the upper part of the chamber until the tobacco in the chamber is at a substantially uniform state of curing, then introducing air into the mass of tobacco laterally from a zone extending vertically within the mass of tobacco to eect its curing and in the course of the curing affording an escape for air from the upper part of the chamber and admitting atmospheric air through a pair of opposite walls of the chamber.

12. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a mass in a pendent position in a chamber, introducing air into the lower part of the chamber only and affording an escape for air from the upper part of the chamber until the tobacco in the chamber is at a substantially uniform state of curing, then introducing air into the mass of tobacco laterally from a zone extending vertically within the mass of tobacco to eiect its curing and in the course of the curing allording an escape for air from the upper part of the chamber, admitting atmospheric air through a pair of opposite walls of the chamber and introducing into the upper part of the chamber air having a moisture content greater than that of the air introduced into the lower part of the chamber.

13. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a chamber in a pendent position in a mass, subjecting vertical exterior portions of the mass directly to atmospheric air and, at the same time, introducing conditioned air under forced flow interiorly of the mass to produce and maintain a positive pressure within the mass to promote a flow of conditioned air laterally in the mass whereby tobacco leaves in exterior portions of the mass will be treated essentially by atmospheric air and tobacco leaves in interior portions of the mass will be treated essentially by conditioned air.

14. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a chamber in a pendent position in a mass, subjecting vertical exterior portions or the mass directly to atmospheric air and, at the same time, directing conditioned air under forced flow interiorly of the mass to produce and maintain positive pressure Within the mass to promote a flow of conditioned air laterally in the mass, whereby tobacco leaves in exterior portions of the mass will be treated essentially by atmospheric air and tobacco leaves in interior portions of the mass will be treated essentially b conditioned air.

l5. The method of curing green tobacco leaves after harvesting which comprises supporting green tobacco leaves in a chamber in a pendent position in a mass, subjecting vertical exterior portions of the mass directly to atmospheric air and, during the curing of the mass, directing conditioned air under forced flow interiorly of the mass to produce and maintain positive pressure within the mass to promote a ow of conditioned a-irlaterllydn the mass, whereby tofoaocefleegfes lin 'exterior portions of the :nase will beftreated essentially'oy atmospheric air and'tobeiccofleaves in interim` portionsof the Will/he treated Vessentially by conditioned air.

1'16. The methodof curing green tobacco leaves vafter harvesting which comprises supporting 'green tobacco lea-ves in a mass in a pendentposition in a Chamber, introducing air under Vpressu're'to a, portion of the mass 'of tobacco laterally lorilyrom a Zone extending vertically Wit'hin'the y1'1'i`a3ss of 'tobacco leaves 4While permitting Yexhaust 'of ali'r from 'the upper portion of the chamber.

Uafter harvesting :17. 'hemetho of curing'greentobacco-leaves which comprises supporting green tobacco leaves ina mass in'a periden'tpos'ition in a chamber 'and in reducing 'heated 5air under pressure laterally only into that portion of the mass-of `tobacco leaves which `is Supported in

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