US2256954A

US2256954A - Apparatus for tobacco treatment

Info

Publication number: US2256954A
Application number: US346815A
Authority: US
Inventors: Jr Horace L Smith; Lucian N Jones
Original assignee: Guardite Corp
Current assignee: Guardite Corp
Priority date: 1937-12-21
Filing date: 1940-07-22
Publication date: 1941-09-23
Anticipated expiration: 1958-09-23

Description

Sept. 23, 1941. H. L. SMITH JR., ETAL 2,256,954

APPARATUS FOR TOBACCO TREATMENT Original Filed Dec. 21, 1937 3 Sheets-Sheet l ATTO RNEYS,

P 1941- H. 1.. SMITH JR.. ET AL 2,256,954

APPARATUS FOR TOBACCO TREATMENT Original Filed Dec. 21, E337 3 Sheets-Sheet 2 1 .7- 45 W37 --45 47 ll i g 47 BY gawfigwww ATTORNEYS.

S Sheets-Sheet 3 H. L. SMITH JR. ET AL APPARATUS FOR TOBACCO TREATMENT Original Filed Dec. 21, 1937 Sept. 23, 1941.

/ NVENj'ORS B M w.

ATTORNEYS.

xamww SJ/O/V/ a /1x204 1:070:99

Patented Sept. 23, 1941 2,256,954 APPARATUS FQR TOBACCO TREATMENT Horace L.

Smith, Jr., and Lucian N. Jones, Richmond, Va., assignors to The Guardite Corporation, a corporation of Illinois Original application December 21, 1937, Serial No. 180,987. Divided and this application July 22, 1940, Serial No. 346,815

4 Claims.

" improved apparatus for altering the moisture content and of exterminating undesired organisms in tobacco.

We have heretofore devised a tobacco treatment process by means of which the moisture content of tobacco may be quickly and easily increased or otherwise adjusted, and by means of which, the expense, delay and losses involved in previously known moistening procedures are avoided. In that process, which is disclosed in detail in our Patent No. 2,086,446, and in our copending application, Serial No. 54,443, filed December 14, 1935, the tobacco is successively subjected to a high vacuum, supplied with steam with a reduction in degree of vacuum, and again subjected to a relatively high vacuum with the result that the moisture content of the tobacco is quickly increased without undesirable discoloration or other deterioration of the tobacco. The successive steaming and re-evacuating steps may obviously be repeated one or more times if desired. As disclosed in our patent above referred to, this process is also efiective in exterminating organisms which infest tobacco.

It is the general object of the present invention to provide improved apparatus which may be used in carrying out these and related processes. We have found that moisture can be supplied to tobacco more effectively and in larger quantities by modifying our aforesaid process as hereinafter explained. The improved apparatus is particularly useful in the treatment of tobacco which is tightly packed in hogsheads, bales or the like, and may also be used in the treatment of loose tobacco. Like the original process, the improved process and apparatus are effective in exterminating pests which infest tobacco in all forms of their life cycle.

A feature of our present invention is supplying both water and steam to the tobacco, the water preferably taking the form of a fine mist or spray entrained in the steam and injected therewith into the evacuated space containing the tobacco. When steam under pressure is introduced to a previously evacuated area, the reduction in pressure, unaccompanied by the performance of work, liberates heat, which results in superheating of the steam. The water introduced with the steam is vaporized, the superheat of the steam supplying the necessary latent heat of vaporization. The steam is thus ie-superheated with the result that unnecessary heating of the tobacco by the steam is avoided. We prefer to introduce with the steam an amount of water considerably in excess to that'necessary to de-superheat the steam at the reduced pressure, whereby excess water, preferably in the form of a fine spray, suspension or mist, is entrained with the steam and carried into contact with the tobacco structure thereby. This is preferably accomplished by breaking up or atomizing a stream of water within or substantially within the previously evacuated treatment chamber at or adjacent the point where the steam is introduced thereto. Other ways of introducing steam and water may be employed, but we believe that the method generally describedis preferable because the water de-superheats the steam as the superheat is developed, and the steam assists in breaking up the excess water into a fine mist or suspension of particles and immediately entrains this mist and carries it into intimate contact withthe tobacco. The introduction of water may accompany each steaming operation whether one or more steaming steps or stages are employed.

The improved apparatus of our invention comprises a novel means for simultaneously injecting steam and water into a previously evacuated treatment chamber in such a manner that the steam is de-superheated and excess water is formed into a fine suspension or mist and introduced with the steam and carried thereby into intimate contact with the tobacco or other material in the chamber. In a preferred embodiment, this means includes a nozzle structure having therein means for directing a stream of water under pressure into impinging contact with a surface whereby the water isbroken into a mist in the presence of the steam. The structure preferably directs the steam adjacent the point of impingement of the water stream, whereby the stream assists in atomizing the water and entrains the water mist (or the proportion thereof which has not immediately vaporized in desuperheating the steam), and sweeps it out of the nozzle opening into the treatment chamber. In one form of the invention, the nozzle structure is so constructed and mounted with relation to a tobacco treatment chamber that impingement of the stream of steam and entrained water against the chamber walls is minimized. This prevents considerable loss of entrained water in the introduced fluid prior to its contact with the tobacco or other material under treatment.

In describing the invention in detail, reference willi 1101c made'to the accompanying drawings, in w c Figure 1 is a diagrammatic and simplified illustration of apparatus capable of carrying out our improved process I Figure 2 is a sectional view of improved steam and water injecting apparatus embodying certain features of our invention; and

Figure 3 is a graph illustrating the various steps to which tobacco may be subjected in a typical treatment cycle embodying certain features of our invention.

Various forms of apparatus. may be employed in carrying out'our improved process. The illustrative apparatus diagram, shown in Figure 1, includes a pair of tobacco chambers .4 and 4' of substelftially identical construction. The two chambers are employed to permit the loading of one at the same time that tobacco is being treated in the other. The process could obviously be carried out in a single chamber. The chambers shown are cylindrical and are provided with removable doors or closures 5 and 5' at each end thereof to permit the introduction and removal of the tobacco to be treated. Since our process involves subjecting the tobacco to a high vacuum, the treatment chambers 4 and 4' are air tight and the doors 5 and 5' are provided with suitable gaskets or other sealing means which prevent the admission of air while a process is being carried out. Each chamber 4 and 4' is preferably large enough to accommodate several hogsheads of tobacco and suitable means may be provided for introducing the hogsheads and removing them from the chambers. Suitable means are provided for selectively evacuating or drawing fluid from the chambers 4 and 4'. Although various means may be used for this purpose, we generally prefer to employ multi-stage steam jet evacuators which we have found to give excellent results. The illustrated apparatus includes a three-stage steam jet evacuating system but a greater or smaller number of stages 'may be used where warranted by the conditions encountered.

As shown, the chambers 4 and 4' are respectively connected through the suction line valves 6 and 6' with a common T fitting I opening into the inlet of a first stage steam J'et ejector or booster 8. The first steam jet booster 3 discharges through a. pipe 9 into an intercondenser ID. The intercondenser 10 may take any suitable form, and as shown, comprises a direct contact condenser of known construction. The intercondenser I is supplied with water through a pipe ll under control of the valve l2. Water and condensate are withdrawn from the intercondenser IO through a pump l3 constructed to prevent the ingress of air to the condenser. The fluid outlet of the intercondenser I0 is connected to the inlet of a second stage steam jet ejector l4 which discharges into a second intercondenser IS. The intercondenser I may be similar in construction to the first stage intercondenser l0, but is preferably of smaller capacity. Water is supplied to the intercondenser l5 from the pipe I I under control of a. valve I 6, and condensate and water are withdrawn by a sealing pump l'l. Two third-stage steam jet ejectors l8 and I8 are connected in parallel to withdrawn fluid from the second intercondenser IS. The ejectors l8 and It may discharge steam and evacuated fluid to the atmosphere directly through an exhaust pipe ill, or a final condenser may be employed to condense the exhaust steam, if desired. A trapped drain 2|! is preferably provided to carry off the liquid which condenses in the exhaust pipe is, and the-liquid from this drain may be either wasted or recirculated through a cooling system the pipes 35' and with the discharge from the condenser pumps l3 and I1.

The steam jet ejectors 3, l4, l3 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 ejectors 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 8 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 ejectors 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 and the automatic valve 26 and manual valve 28 control the admission of steam to the third stage ejector l8 and 13 in parallel.

Suitable means are provided for admitting steam to the treatment chambes 4 and 4'. 'In the disclosed embodiment, steam is introduced at a plurality of points spaced longitudinally by means of the manifold pipes 21 and 21' and the branch pipes 28 and 28' 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' 28, and

manual valves 30 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 hereinafter explained. Water may be introduced with the restricted steam supply if desired. Automatic control valves 32 and 32' are provided in the by-pass pipes 3| and 3| respectively.

In accordance with one embodiment of our invention, water isintroduced to the treatment chambers with steam, and for this purpose, water manifold pipes 33 and 33', each having branch pipes 34 and34', are provided for the respective chambers 4 and 4'. The branch pipes 34 and 34' are connected to s aced 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 28'. 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 53 and 50' may also be provided for this purpose.

Suitable means are provided for venting the chambers 4 and 4' to the atmosphere. Asshown, 35', controlled respectively by the valves 36 and 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 conven-v ient point.

The supply of steam and water to the steam jet ejectors and the introduction of these 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 indicat the different types of actuation which may be resorted to. The suc-.

tion line controlled valves 6 and 6' are preferably 36' are used for this purpose.

)1 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 chambers 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 enter the chamber. We have devised an improved apparatus for performing this function and it is illustrated in Figure 2. In this figure, the wall of a treatment chamber is illustrated at 4, a steam supply pipe at 23' and a water supply pipe at 34. These parts may comprise the correspondingly designated parts of the apparatus shown in Fig. 1.

The water and steam injecting device or nozzle shown comprises a hollow inlet bushing 31 connected to the inner end of a collar 38 which is welded or otherwise sealed in an opening through the wall of the chamber 4. The collar 38 is connected through a nipple 39 and a T fitting 49 to the steam supply pipe 28 and the water supply pipe 34 passes axially through the

parts

38 and 39 and is sealed in an opening of the T fitting 49 by a suitable packed gland 41. The end of the water pipe is fixed to a water nozzle fitting 42 in communication with a central water passage 43 of small bore which terminates in a nozzle opening 44. The fitting 42 is threadedly connected within the inlet bushing 31 and is provided with a plurality of steamopenings 45 disposed about the central water passage 43. A deflecting disc D is fixed in spaced relation to the inner end of the fitting 31 by suitable means such as the bolts 41. The disc D extends across let of the fitting 31 and preferably comprises a plane circular central portion 48 surrounded by a frustoconical or tapered rim portion 49. The disc D cooperates with the inner end of the fitting 31 to form a finid outlet nozzle which directs the discharged fluid outwardly substantially par allel to the wall of the treatment chamber.

Water is supplied through the pipe 34 at a relatively high pressure and accordingly issues from the water nozzle 44 in a fine stream at high velocity and impinges upon the plane central portion 48 of the disc D where it is broken up into a fine mist or suspension. The steam from the pipe 28 flows through the openings 45 toward the disc D, and aids in breaking up the water into fine particles. The contact between the water and steam at the reduced pressure within the treatment chamber results in the vaporization of some of the water with a resultant de-superheating of the steam, and the excess water over that thus vaporized is entrained by the steam and carried out through the nozzle opening formed by the disc D and the fitting 31. Since the nozzle opening directs the injected fiuid in an initial path substantially parallel to the treatment chamber wall, the loss of water from this fiuid by impinging contact against the chamber wall at high velocity is minimized.

After curing, tobacco is customarily tightly packed in hogsheads, bales or the like and is aged in warehouses for periods which may run to several years. The tobacco loses moisture during aging and as a result becomes so dry and brittle that is cannot be unpacked, much less handled or stemmed, without excessive loss from shattering, tearing or powdering of the leaf structure. The process of the present invention may be employed to increase the moisture conthe out-' tent at various stages during the preparation or shipment of tobacco, and also to exterminate organisms in tobacco with or without altering its moisture content. The process has proven particularly effective in the'so-called ordering" of aged and relatively dry packed tobacco, that is, increasing the moisture content of such tobacco to a point where it can be unpacked and stemmed without substantial breakage of the leaf structure. Our process will be here described by reference to a typical example thereof as employed in ordering tobacco.

The tobacco, which is usually packed in hogsheads or bales, is placed within one of the treatment chambers, for example, the chamber 4. The heads may be removed from the hogsheads before treatment if desired, but this operation is not essential since tobacco hogsheads are not fluid tight. The doors 5 of the treatment chamber 4 are closed and the tobacco is subjected to a series of operations which have been graphically illustrated in Figure 3, where the ordinates represent absolute pressure in the treatment chamber in inches of mercury, and the abscissa represent time in minutes.

The tobacco in the treatment chamber 4 is first subjected to a relatively high vacuum, as indicated by the portion abcd of the curve in Figure 3. The degree of vacuum should be such as to remove substantially all of the air initially contained in the treatment chamber and the interstices of the structure of the tobacco therein. We have found that the degree of vacuum required for this purpose varies somewhat with the .temperature of the tobacco. Thus with tobacco having an initial minimum temperature of about 70f F. or higher, a vacuum from 29.5 to 29.6 inches of mercury (.5 to .4 inch Hg absolute pressure) is sufficient, whereas with lower initial minimum temperatures of the tobacco mass,

v vacuums as high as 29.85 to 29.95 or even higher may be required. In the example illustrated in Figure 3, the, initial minimum temperature of the tobacco mass is assumed to be in the neighborhood of 70 F., and the initial vacuum is drawn to about 29.65 inches of mercury (.35 inch of Hg absolute pressure).

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 6 is opened and the valve 6' controlling the chamber 4 is closed, the

valves

36, 23,

and 46 being closed. The steam supply valve 26 for the third stage ejectors l8 and I8 is opened and these ejectors, acting in parallel, reduce the absolute pressure by withdrawing fiuid from the treatment chamber 4 as indicated by the portion ab of the curve abce in Figure 3. At about the point b, it is preferred to start the second stage ejector l4 and this is done by opening the steam valve 25. At the same time, cooling water is admitted to the second intercondenser I5 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 18'. When the absolute pressure of the chamber has been further reduced to a value such as that indicated by the point 0 on the curve, the first stage booster 8 and first intercondenser III are operated by opening the steam valve 23 and the water valve 12. With all of the ejectors in operation, the absolute pressure on the tobacco is rapidly re- 3 to an intermediate duced to. the desired final value, as indicated by the point d in Figure 3. As shown in Figure 3, the entire evacuating operation can be completed in a relatively short interval, less than twelve minutes in the illustrative example shown. At the conclusion'of the initial evacuating step, the suction line valve is closed and the ejectors and intercondensers are shut down by closing the valves 23, i2, 25, I6 and 26.

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 simultaneously 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 efi'ected by opening the steam valve 29 and the water valve 46, and the pressure within the chamber increases as shown at de on Figure but preferably sub-atmos- Dheric value. We believe that the excess water introduced is carried into intimate contact with the tobacco by the steam which flows rapidly intothe previously evacuated tobacco structure. In this manner, the moisture content of the tobacco is increased, both by the condensation of steam and by the water introduced with the steam During the steaming step, the absolute press re should be increased to such a value that the 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 sion of the steaming step, should not be so high as to cause discoloration or other heat deterioration of the tobacco tained. 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 sufliciently 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. In the example disclosed in Figure 3, it is assumed that bright tobacco is under treatment, and the absolute pressure at the end of the steaming step is about ten inches of mercury (a vacuum of about 20 inches of mercury). When the process is applied to burley tobacco, which is more resistant to heat than bright tobacco, the absolute pressure at the end of the steaming step may reach a value in the neighborhood of 12 inches of mercury (a vacuum of 18 inches of mercury).

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 step is terminated by closing the steam and water valves 29 and IS.

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 of a fine mist or suspension, is carried into the tobacco structure by the steam; The amount attained at the conclu-.

I lbs. per square inch assuming that 25 lbs. per

of water so introduced is not critical, and amounts from twice to four or iive times the amount necessary to de-superheat the steam may be used. In a typical example of our process,

minute of dry saturated steam at an initial pressure of about 115 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 suiiicient to saturate (de-superheat) the steam introduced at each branch pipe.

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 steamas it enters the chamber. The atomizing or breaking up of the water may be promoted by the use of known type of atomizingor spray nozzles, or the improved nozzle illustrated in Figure 2 and described above may be employed for this purpose. 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 may be provided at each inlet point and within the time interval during which the elevated temperature is mainlocated adjacent each tobacco hogshead.

A so-called soaking step preferably follows the introduction of steam and water. During this portion of the process, the absolute pressure on the tobacco is maintained constant or nearly constant for a limited time interval as indicated by the portion cf of the curve of Figure 3. The previously introduced steam continues to condense after the introduction of steam has been discontinued, and accordingly, the pressure in the chamber 4 would, normally fall during the "soaking period. Accordingly, we prefer to introduce steam at a low rate substantially sufllcient to continuously replace the steam being condensed, whereby the absolute 1 pressure on the tobacco is maintained substantially constant. This may be accomplished by opening the steam valve 32 in the restricted bypass pipe 31, it being understood that the rate of steam flow through this pipe is reduced by the pipe size, a'restricted orifice or otherwise to produce the desired continuous replacement of the steam being condensed in the chamber. The introduction of steam at a restricted rate during the soaking stage may, if necessary or desirable, be accompanied by the introduction of water in the form and amounts explained above. The soaking step is terminated by closing the valve 22.

At the conclusion of the "soaking step, the tobacco is subjected to an-increased vacuum, the pressure thereon being reduced as indicated by the portion fa of the curve in gure'" 3. 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 vaporization. This re-evacuating step may comprise the iinal step of the process, and the evacuation preferably continues to an absolute pressure at which sufllcient moisture has been evaporated or vaporized to reduce the tobacco temperatures in the perature to a safe value. The heat discoloration and other heat deterioration of tobacco is a function of the temperature, the time for which the temperature is maintained and the type of tobacco under treatment. If certain types of bright tobacco are maintained at'temperatures above about 125 F. for an extended time interval, 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 temneighborhood of about 180 F. 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 jg of our process is continued to a value of vacuum at which the temperature of he tobacco 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 re-evacuating step may be somewhat above the minimum temperature at which heat deterioration can take place after an extended interval. If the tobacco is not to be unpacked at the conclusion of the process, the re-evacuation is continued until the tobacco temperature is below the lowest temperature at which it can be adversely effected, by heat in any time interval.

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 fa. 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 of mercury 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 jg may be performed by operating the third stage ejectors l8, l8 and the first stage intercondenser i until the absolute pressure has been reduced to some intermediate point, such as the point k. The second stage ejector l4 and the second intercondenser l5 may then be operated by opening the valves 25 and i6 and the absolute pressure is further reduced to the point g by the second and third stage ejectors acting in series. If desirable or necessary, the first stage 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 tothe ejectors and intercondensers.

At the conclusion of the treatment chamber for intervals of the re-evacuating step jg, 4 is vented by opening has been reduced on the tobacco indicated by the the valve 36, and the pressure rises toatmospheric pressure as curve section gh. The tobacco is now removed from the treatmentchamber 4 and the processis V complete.

It is obvious that the above described steaming and re-evacuating steps may be repeated one or more times if desired. One such repetition has been illustrated by the broken line curves starting at the point a in Figure. 3. Since a second steaming, "soaking and re-evacuating cycle consumes only a short time interval, the tempera; ture to which the tobacco is cooled in the first re-evacuating step may be somewhat higher than the temperature required at the conclusion of the treatment. Thus; as shown in Figure 3, the first re-evacuating step may continue until the absolute pressure is reduced to about 4 inches of mercury (a vacuum of 26 inches of mercury). In general, a practical working range of absolute pressures at the conclusion of an initial re-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 ejectors l8 and I8 and the first intercondenser I0 only, although operation of the second stage ejector l4 and second intercondenser l5 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. The second steaming step is indicated by the broken line g'h', the second soaking step is indicated by the line hi and the second re-evacuating step is indicated by the broken curve section y'k'l. These steps may be respectively performed by manipulating the apparatus as described above in connection with the steaming, soaking and re-evacuating steps represented by the curve sections de, ef and IQ. The second steaming step gh' is usually of shorter duration than the first steaming step de, the absolute pressure on the tobacco at g being somewhat higher than that at d, and the final steaming or soaking pressures being substantially the same in each case. At the end of the final re-evacuating step a'k'l, the treatment chamber is vented to the atmosphere, as indicated by the line lm, 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 net change in the moisture content. In the latter case, the reevacuating step is continued until all of the added moisture has been evaporated or vaporized and removed.

It should be understood that the described examples ar merely illustrative and that our invention is not limited to the values of pressure and vacuum or the time intervals set forth above and indicated in Figure 3. The various features of our invention may be separately employed.

Although the process practiced in the apparatus of the present invention has been described may be applied to other steps in the treatment of tobacco or other materials where it may be found applicable. For example, we have found that our above described process is effective in destroying mold and mold spores which sometimes appear in aged tobacco. We have also found that our process is eflective in tempering and improving the quality of cased tobacco, that is, tobacco to which flavoring materials have been added. In either the destruction of mold or mold spores or the tempering of cased tobacco, our process may be so conducted as to increase the moisture content of the tobacco or without net chang in the moisture content, and in the latter case, the re-evacuation is continued until all or substantially all of the added moisture has been evaporated. This application is a division of our application Ser. No. 180,987, flied Dec, 21, 1937 which has matured into Patent 2,217,935, dated Oct. 15, 1940.

We claim:

1. Apparatus for injecting a mixture of water and steam into a treatment chamber comprising a water nozzle, a plate aligned with but spaced from said water nozzle and disposed across the path of water issuing from said nozzle, and means adjacent said water nomle for directing steam into contact with said plate in a path substantially parallel to and surrounding the water issuing from said water nozzle.

2. Apparatus for injecting a mixture of water and steam into a treatment chamber comprising tral portion thereof and a restricted nozzle having a substantially straight bore, a plate extending across said nozzle and spaced therefrom in the path of fluid issuing from said nozzle, a plurality of fluid openings adjacent said nozzle and directed toward said plate and means for supplying water to said nozzle and supplying steam to said fluid openings. 3. Apparatus for injecting a mixture of water and steam into a treatment chamber comprising a. water nozzle having a restricted bore. a plate having a substantially plane surface spaced from and disposed across and in alignment with the bore of said water nozzle and having tapered edges, and a plurality of steam nozzles disposed around said water nozzle and directed toward said plate.

4. Apparatus for injecting a mixture 'of water and steam into a treatment chamber comprising a substantially circular plate having a plane central portion and tapered marginal edges, means spaced from said plate for directing a stream of water into impinging contact with said plane cenmeans spaced from said plate for directing steam against said plate ad- Jacent the point where the water impinges thereon.

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