US2285469A - Method for moistening tobacco - Google Patents

Description

June 9, 1942. H. 1.. SMITH, JR., ETAL 2,285,469

METHOD FOR MOISTENING TOBACCO Filed July 22, 1940 n J 2.9 [a

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Patented June 9, 1942 METHOD FOR MOISTENING TOBACCO Horace L. Smith, Jr., and Lucian-N. Jones, Rich-'- mond, Va, assignors ration, a corporation of Illinois to The Guardite ApplicationJnly 22, 1940, Serial No. 348,814

V This invention relates to a method for moistening tobacco under vacuum, and more particularly to improvements in the use of multiple chambers.

removal of the tobacco to be treated. The treat- 'ment chambers are airtight and the doors are Devices for the moistening of tobacco under vacuum are now in wide use in which tobacco in hogsheads, bales or other packages, is placed in an airtight chamber, and subjected to a high vacuum and then is supplied with steam to reduce the vacuum. In many of these processes the vacuum is again increased after the steaming operations and these steps may 'be repeated one or more times. One 0! the diillculties encountered in speedy handling of tobacco is the time necessary for removing hogsheads from the treating chamber and the introduction 'of the new batch of tobacco therein. Not only is time lost in this interchange but if an attempt is made to hurry the processes, the workmen are required to enter chambers which are exceedingly hot and moist, which in some cases is objectionable.

In accordance with the present invention, a plurality of chambers is employed by means of which the time lost in loading and unloading the chambers is eliminated, it being even possible to air the chambers for some time before emptying them. Furthermore, a large saving in steam consumption and in pumping costs may be accomplished by interconnection of the chambers so that instead of breaking the vacuum to atmosphere as the final step, an evacuated chamber is connected to an unevacuated chamber and thereby accomplishes the first stages of air removal from the latter. The invention has the additional advantage that by use of multiple chambers one of the chambers and the product within it may be utilized as a condenser by means of which a warmer chamber and the tobacco'in it may be cooled. This also means that the steam necessary to heat and moisten the cooled tobacco is supplied by the warmer tobacco, whereas, otherwise the exhausted steam is wasted.

The invention isillustrated diagrammatically in the drawing in which a pair of tobacco chambers 4 and 4' of substantially identical construction are included. While two chambers are shown in the present arrangement, any convenient multiple number of chambers may be used, if desired, the number being dependent upon the time required for loading and other desirable features as will become evident from the following description. The chambers shown may be of any desired shape whether cylindrical or rectangular, those illustrated being cylindrical. They are provided with removable doors or closures 5 and 5' at each end thereof to permit the introduction and provided with suitable gaskets or other sealing means which prevent the admission of air during the evacuation cycles. Each chamber is preterably large enough to accommodate several hogsheads of tobacco, or an equivalent volume of tobacco or other products Suitable means are provided for selectively evacuating the chambers l and 4' it being generally preferable to employ multi-stage steam jet evacuators for this purpose, or at least for the latter stages of the evacuation.

.The illustrated apparatus includes a three-stage steam jet evacuating system.

As shown, the chambers l and 4" are respectively connected to the suction line valve 6 and 6' with a common T fitting I, opening into the inlet of a first stage steam jet ejector or boostert. The first steam Jet booster 8 discharges through a pipe 9 into an intercondenser Ill. The intercondenser l0 may take any suitable form, and, as shown. comprises a direct contact condenser of known construction. It is supplied with water through a pipe ll under control of the valve l2. Water and condensate are withdrawn from the intercondenser i0 through a pump it constructed to prevent ingress of air to the condenser. The fluid outlet of the intercondenser In is connected to the inlet of a second-stage steam let ejector ll which dischargesv into a second intercondenser I. The intercondenser I! may be similar in construction to the first-stage intercondenser it, but is preferably of smaller capacity. Water is supplied to the intercondenser l5 from the pipe i I under control of a valve l6, and condensate and water are .withdrawn by a sealing pump l1. Two third-stage steam jet electors i6 and i8 are connected in parallel to withdraw fluid from the second intercondenser IS. The electors l8 and I! may discharge steam and evacuated fluid to the atmosphere directly through an exhaust pipe l9, or a final condenser maybe employed to condense the exhaust steam, if desired. A trapped drain 20 is preferably provided to carry 01! the liquid which condenses in the exhaust pipe l9, and the liquid from this drain may be either wasted or recirculated through a cooling system with the discharge from the condenser pumps l3 and I'I.

The steam jet electors 8, i4, i8 and I8 are of known construction, each employing a jet of steam to propel and compress gaseous fluid by entrainment in a restricted throat. High pressure steam for operating the electors is supplied from any suitable source through a pipe 2| in which a separator 22 of known construction may be connected.

The first-stage steam booster. I receives steam through a branch pipe 22' under the control of an automatic valve 23 and a hand valve 23'. The second and third-stage electors receive steam from the pipe 24. The automatic valve 25 and manual valve 25' govern the admission of steam to the second-stage ejector l4 andthe automatic valve 26 andmanual valve 23' control the admission of steam to the third-stage ejector l8 and II in parallel.

Suitable means are provided for admitting steam to the treatment chambers 4 and 4'. In the disclosed embodiment, steamisintroduced at a plurality of points spaced longitudinally by means of the manifold pipes 21 and 21' and the branch pipes 28 and 29' which terminate in openings in the chamber walls. The manifold pipes 21 and 21' are connected to the steam supply pipe 2| through automatic control valves 29 and 29', and manual valves 3|! and 30' may also be used at this point, as shown. Restricted by-pass pipes 3| and 3| are preferably connected respectively around the automatic steam control valves 29 and 29' to admit steam at a restricted rate to the chambers 4 and 4' at certain times, as here inafter explained. Water may be introduced with the restricted steam supply, if desired. Automatic control valves 32 and 32' are provided in the by-pa-ss pipes 3| and 3| respectively.

In accordance with one embodiment of our invention, water is introduced to the treatment chambers with steam, and for this purpose, water manifold pipes 33 and 33', each having branch pipes 34 and 34, are provided for the respective chambers 4 and 4'. The branch pipes 34 and 34' are connected to spaced openings in the walls of the chambers 4 and 4 respectively, and preferably enter these chambers at the same points as the branch steam pipes 28 and 29. The admission of water is controlled by the automatic valves 46 and 46' in the manifold pipes 33 and 33' respectively and manually operable valves 50 and 50' may also be provided for this purpose.

Suitable means are provided for venting the chambers 4 and 4' to theatmosphere. As shown, the pipes 35 and 35', controlled respectively by the valves 36 and 36', are used for this purpose. The pipes 35 and 35' are shown as connected to the chambers 4 and 4' through the fittings which connect the suction line valves 6 and 6' to the chambers. The vent pipes could obviously be connected "to the chambers at any other convenient point.

The supply of steam and water to the steam jet ejectors and the introduction of thes fluids to the treatment chambers, as well as the venting and evacuation of the chambers, may be controlled manually by separate valves, manually from a central point or by suitable automatic control apparatus; The particular form of control valve actuation employed forms no part of the present invention but in many instances both manually operable and automatic valves have been disclosed to indicate the difierent types of actuation which may-be resorted to. The suction line controlled valves 6 and 6 are preferably of large capacity and are usually operated by diaphragm or electric means of known construction.' The remaining automatic valves may be similarly operated.

In accordance with one feature of our invention, water is introduced to the treatment chainbers with the steam during the steaming steps or stages including the soaking stage, if desired, and

is converted into a fine mist or suspension and entrained with the steam as the two fluids enterof allair from the chamber, after which the to- ,bacco is steamed with a mixture of steam and water hereinbefore described, after which it may again be subjected to an increased vacuum followed by further steaming. These cycles can be repeated as often as is necessary to insure proper treatment of the tobacco. In these treatments the degree of initial vacuum employed will, of course, depend upon the temperature of thetobacco. Usually the evacuation is continued until the pressure has dropped below .5 inch of mercury absolute and sometimes is reduced as low as .05 to .15 inch of mercury absolute.

The steam jet evacuating equipment described may be operated in various ways to produce the desired initially high vacuum and the following sequence of operations has been found effective and economical. The suction line valve 8 is opened and the valve 6' controlling the chamber 4' is closed, the valves 36, 23, I2, 25, I6, 29, 32

' and 46 being closed. The steam supply valve 24 for the third-stage electors l8 and I9 is opened and these ejectors, acting in parallel, reduce the absolute pressure by withdrawing fluid from the treatment chamber 4. When the pressure is dropped to about 10 inches absolute, it is preferred to start the second-stage ejector l4 which is done by opening the valve 25.- At the same time, cooling water is admitted to the second intercondenser l5 by opening the water valve l6, and in this manner, the steam issuing from the ejector I4 is condensed before it reaches the third-stage ejectors l8 and It. When the absolute pressure of the chamber has been further reduced to a value such as about 2 inches, the first-stage booster 8 and first intercondenser III are operated by opening the steam valve 23 and the water valve l2. With all of the electors in operation, the absolute pressure on the tobacco is rapidly reduced to the desired final value. The entire evacuating operation can be completed in a relatively short intervaLfor example, less than twelve minutes. At the conclusion of the initial evacuating step, the suction line valve is closed and the electors and intercondensers are shut down by closing the valves 23, I2, 25, I6 and 29.

After the desired high vacuum has been attained, steam is supplied to the tobacco whereby the vacuum thereon is reduced. In accordance with one feature of our invention, water is supplied to the tobacco sirnultaneously with the steam, the amount of water so supplied being greater than that required to de-superheat the steam at the vacuum obtaining in the chamber. The simultaneous addition of water and steam is effected by opening the steam valve 29 and the water valve 46, and the pressure within the chamber increases to an intermediate but preferably sub-atmospheric value. We believe that the excess water introduced is carried into intimate contact with the tobacco by the steam which flows rapidly into the previously evacuated tobacco structure. In this manner, the moisture content of the tobacco is increased, both by the 2,285,408 I chamber l would normally fall during the "soakcoudensation of steam and by the water introduced with the steam. I

During the steaming step, the absolute pressure should be increased to such a value that the I steam, and entrained water where water is introduced therewith, will quickly penetrate the tobacco mass and moisten it substantially uniformly throughout. The steam introduced heats the tobacco and raises its temperature, and the amount of steam introduced, as determined by the absolute pressure attained at the conclusion of the steaming step, should not be so high as to cause discoloration or other heat deterioration of the tobacco within the time interval during which the elevated temperature is maintained. In accordance with our process, the absolute pressure attained in the steaming step produces a tobacco temperature high enough to cause discoloration of the tobacco after a time interval, but prior to the expiration of such interval, the absolute pressure is reduced suiliciently to appreciably lower the tobacco temperature, whereby discoloration or other heat deterioration is avoided. ,This reduction of absolute pressure takes place in the re-evacuating step or steps as hereinafter described. With various varieties of tobacco and times of treatment, the final steaming pressure may vary between about 8 and; 18 inches of mercury absolute. The steaming stem is terminated by closing the steam and ava'te'r valves 29 and 48.

The amount of water introduced during'the steaming step is preferably in excess of that required to de-superheat the steam supplied to the tobacco whereby an excess of water, in the form jbf a fine mist or suspension, is carried into the tobacco structure by the steam. The amount of water so introduced is not critical, and amounts from twice to four or five times the amount necessary to de-superheat the steam may be used. In a typical example of our process, assuming that 25 lbs. per minute of dry saturated seam at an initial pressure of about 115 lbs. per square inch gauge is introduced through each branch pipe 28, about .7 gal. of. water per minute may be introduced with the steam through each branch pipe 34. In the example given, assuming an initial vacuum of about 29.5 inches of mercury in the chamber, approximately .35 gal. per minute of water would be suflieient to saturate (desuperheat) the s eam introduced at each branch.

The water is preferably introduced to the tobacco chamber at the same point as the steam whereby the steam is de-superheated as the superheat develops and the water is broken-up and entrained by the steam as it enters the chamber. The atomizing or breaking up of the wa er may lag" period. Accordingly, we prefer to introduce steam at a. low rate substantially sufllcient to continuously replace the steam being condensed, whereby the absolute pressure on the tobacco is maintained substantially constant. This may be accomplished by opening the steam valve 32 in the restricted by-pass pipe 8!, it being understood thatthe rate of steam flow through this; I pipe is reduced by the pipe size, a restricted orifice or otherwise to produce the desired continuous replacement of the steam being condensed inthe chamber. The introduction of steam at :a

be promoted by the use of known types of atom- I izing or spray nozzles. One or more combined water and steam inlets may be provided, and good results are obtained by using one such inlet for each hogshead, bale or other mass of tobacco in the treatment chamber 4. When our improved steam and water injecting nozzle is used; one such device maybe provided at each inlet point and located adjacent each tobacco hogshead.

A so-called "soaking step preferably follows the introduction of steam and wa-er. During this portion of the process, the absolute pressure on the tobacco is maintained constant or nearly constant for a limited time interval. The previously introduced steam continues to condense after the introduction of steam has been discontinued, and accordingly, the pressure in the restricted rate during the soaking" stage may, if necessary or desirable, be accompanied by the introduction of water in the form and amount explained above. The soaking step is terminated by closing the valve 32. a

At the conclusion of the "soaking step, the tobacco is subjected to an increased vacuum, the pressure thereon being reduced. The degree of evacuation to which the tobacco is subjected in this step is preferably high enough to vaporize or evaporate some moisture from the tobacco whereby its temperature is reduced, heat being absorbed in the form of latent heat of vaporiza tion. This re-evacuating stepmay comprise the final step of the process, and the evacuation preferably continues to an absolute pressure at which suflicient moisture has been evaporated or vaporized to reduce the tobacco temperature to a safe value. The heat discoloration and other heat demaintained and the type of tobacco under treatment. If certain types of bright tobacco are maintained at temperatures above about F- for an extended time interval, the discoloration and often other forms of heat deterioration take place, and the value of the tobacco is thereby substantially reduced. However, these tobaccos may be maintained at temperatures in the neighborhood of about F. for intervals of about 10 or 15 minutes without discoloration or other detrimental change. In general, bright tobacco is more sensitive to heat than other varieties-burley tobacco, for example, will withstand high temperatures for appreciably longer periods than will bright tobacco.

The re-evacuating step of the process is continued to a value of vacuum at which the temperature of the tobacco has been reduced by the evaporation or vaporization of moisture to a value at which heat deterioration will not take place. This temperature, and accordingly, the final value-of vacuum, varies as indicated above, depending upon the type of tobacco under treatment. The treatment to which the tobacco is subjected after the conclusion of our process is also a factor in fixing the final tobacco temperature. In most cases, the tobacco is unpacked from the hogsheads or bales and the leaves are separated immediately after the ordering" treatment. With this procedure, the tobacco is cooled by the atmosphere promptly after the treatment process is concluded and accordingly the temperature to which the tobacco is reduced In the disclosed example, assuming bright tobacco is under treatment and is to be unpacked at the conclusion of the process, the re-evacuating step' is continued to a vacuum of about 27.25 inches of mercury (2.25 inches of mercury absolute pressure). This final vacuum may vary from about 25 to about 29.8 inches of mercury (5 to .2 inches ofmercury absolute pressure) and in the case of very dark heat resistant tobaccos. which are to be unpacked immediately after treatment, the final vacuum may be as low as 20 inches of mercury (10 inches; of mercury absolute pressure).

The re-evacuating step may be performed by operating the third-stage ejectors I8, l8 and the first-stage intercondenser it until the absolute pressure has been reduced to some intermediate point. The second-stage ejector 14 and second intercondenser I! may then be operated by opening the valves 25 and I6 and the absolute pressure is further reduced to the desired point by the second and third-stage ejeotors acting in series. If desirable or necessary, the firststage booster 8 may also be operated in drawing the desired vacuum. The re-evacuation step is concluded by closing the suction line valve 6 and cutting off the supply of steam and water to the electors and intercondensers.

At the conclusion of the re-evacuating step, the treatment chamber 4 is vented by opening the valve 36, and the pressure on the tobacco rises to atmospheric pressure. The tobacco is now removed from the treatment chamber 4 and the process is complete.

It is obvious that the above described steaming and re-evacuating steps maybe repeated one or more times if desired. Since a second steaming, "soaking and re-evacuating cycle consumes only a short time interval, the temperature to which the tobacco is cooled in the first re-evacuating step may be somewhat higher than the temperature requiredat the conclusion of the treatment. In general, a practical working range of absolute pressures at the conclusion of an initialre-evacuating step may be from about 3 to about 5 inches of mercury absolute.

The first re-evacuating step in the case of recycling may be accomplished by manipulating the apparatus as described above. It is usually necessary to operate the third-stage electors l8 and I8 and the first inter-condenser l only, although operation of the second-stage ejector i4 and second intercondenser l may be resorted to during a part of the re-evacuating step, if necessary or desirable.

The re-evacuating step just described is followed successively by a repetition of the steaming, "soaking" and re-evacuating steps. At the end of the final re-evacuating step the treatment chamber is vented to the atmosphere, and the tobacco is removed from the chamber. The "soaking step is believed to aid in the uniform distribution of moisture in the tobacco. By introducing water with the steam, the amount of moisture added to the tobacco is increased without undesirably increasing the maximum temperature to which the tobacco is heated.

Our improved process exterminates tobacco pests, such as the cigaret beetle, in all forms of its life cycle. This can be done simultaneously with the addition of moisture as described above, or without not change in the moisture content.

In the latter case, the re-evacuating step is con- The foregoing description illustrates the general operations carried out in any one chamber. In operating a pair of chambers together, it will be seen that there are many occasions on which the tobacco in one chamber may be at a higher pressure than the tobacco in the other and it is desired to reduce the tobacco at the higher pressure to some lower pressure. These occasions occur, for example,'when one chamber has just been filled with tobacco and is under full atmospheric pressure and the other chamber has passed through its entire cycle of operation and is under a relatively low pressure under an atmosphere of steam. In such case, both valves I and 8' may be opened, the steamjet ejector being in such case shut on from the atmosphere by any suitable means. The result of such opening of valves 8 and 8' is to equalize the pressure in the two containers thereby producing a vacuum of 10 to 14 inches in each tank far more rapidly than would be the case with any mechanical evacuation system andwithout cost.

In other stages of the evacuation system the two tanks may be in even more favorable relationship from the standpoint of the advantages of interconnecting the two. For example, if tank 4 is at maximum evacuation of .4 inch and tank 4' is at a pressure of 10 inches of steam, interconnection ofthe two chambers produces a totally new effect. Under these conditions each chamber has an atmosphere of steam but the pressure and temperature in the two chambers difier. In such a case the tobacco in chamber 4 being cold will act as a condenser and will draw from chamber 4' the steam contained therein, thus lowering the pressure. At the same time, the reduction in pressure will cause evaporation of moisture from the tobacco in chamber 4' and this evolved moisture will be further condensed by the tobacco in chamber 4 until the temperature of the tobacco in both chambers is substantially equal. In this way not only is the work of evacuating chamber 4' over this range eliminated, but the steam whichwould have had to be supplied to the tobacco in chamber 4 is saved.

Moreover, each evacuation of steam from tobacco eliminates by a process of steam distillation certain ingredients from the tobacco, and by this process these ingredients are saved to the extent that such steam is re-condensed in the other tobacco.

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

We claim:

1. The method of treating tobacco and the like which comprises subjecting two lots of tobacco in separate zones to vacuum and producing an atmosphere substantially completely of steam about the tobacco in each lot, the pressure in one lot being relatively high as compared with the other, and the tobacco therein being relatively moist as compared with the other, and then interconnecting the two zones, whereby the lot of tobacco under lower pressure acts as a condenser and its temperature and moisture content are increased while the other lot of tobacco is cooled and its moisture content is decreased.

2. The method of treating an organic product in which the product is submitted to a plurality of cycles in an atmosphere substantially completely of a condensible gas during which the temperature and pressure upon the organic product are alternately increased and diminished, the steps of carrying out the alternation of cycles upon two lots of the product in cooperation in adjacent chambers and utilizing the lot of the product under a relatively high vacuum portion placed substantially completely with an atmosphere of steam, the additional steam being introduced to the product to raise its temperature and pressure, and the pressure then reduced in the product to decrease its temperature and moisture content, characterized by utilizing one lot of the product under high vacuum in an atmosphere of steam as a condenser for another lot of the product under relatively high pressure 10 and temperature in an atmosphere of steam.

HORACE L. SMITH, JR. LUCIAN N. JONES.

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