US2245833A

US2245833A - Apparatus for varying moisture content

Info

Publication number: US2245833A
Application number: US248034A
Authority: US
Inventors: Jr Horace L Smith; Lucian N Jones
Original assignee: THERMAL ENGINEERING CORP
Current assignee: THERMAL ENGINEERING Corp
Priority date: 1938-12-28
Filing date: 1938-12-28
Publication date: 1941-06-17
Anticipated expiration: 1958-06-17

Description

[fl-AL v June 17, 1941.

H. L. SMITH, JR, APPARATUS FOR VARYING MOISTURE CONTENT 3 Sheets-Sheet l Filedpec. 28, 1938 m; WK .w LWFILE mhw Qwm l 1 l I I l ll WW June 17, 1941. L SMITH, JR., r 2,245,833

APPARATUS FOR VARYING MOISTURE CONTENT Filed Dec. 28, 1938 3 Sheets-Sheet 2 x INYENTORJ v BYM pwmu I Qam' M ATTORNEYS June 1941- H. L. SMITH, JR., L 2,245,833

APPARATUS FOR VARYING MOISTURE CONTENT Filed Dec. 28, 1938 3 Sheets-Sheet 3 INVENTOR f JM 9.. BY M 41. M Y

ATTORNEYS Patented June 17, 1941 APPARATUS FOR VARYIhlG MOISTURE CONTENT Horace L. Smith, Jr., and Lucian N. Jones, Richmond, Var, assignors, bymes'n'e assignments, to Thermal Engineering'Corporation, Richmond, Va., a corporation of Virginia Application December 28, 1938, Serial No. 248,034

8 Claims.

This invention relates to the variation of the moisture content of porous substances and more particularly concerns an improved apparatus for increasing or decreasing the moisture content of tobacco or like materials.

At various stages during the preparation and shipment of tobacco, it is necessary to alter its moisture content. For example, when tobacco is shipped abroad, tarifi regulations require that it have a specified minimum moisture content.

provided by the regulations, penalties or fines are imposed. On the other hand, any excess of moisture over the required minimum adds materially to the shipping weight and cost, as well as to the duties imposed. It has heretofore been the practice to store tobacco intended for eX- port shipment until the prevailing atmospheric conditions bring its moisture content to approximately the required value. This practice involves tying up very large quantities of tobacco for extended periods and does not produce the exact moisture content desired in any case.

The moisture content of tobacco must be re duced or altered at various stages during its han dling and treatment. After tobacco has been harvested and flue-cured by the grower, it is usually desired to age the tobacco in a packed condition for prolonged periods. The moisture content of cured tobacco, usually called greenZ tobacco, is so high that it will mould or mildew and otherwise deteriorate if packed without a drying treatment. It has accordingly been custom-ary to subject the tobacco to a so-called redrying? operation before it is packed for aging,

to some extent. 1

After this re-drying operation, the leaf bun dles are tightly packed in hog-sheads, bales or the like, usually by hydraulic pressure. At the low moisture content necessary to avoid develop-:

ment of mould during aging or shipment, the tobacco leaves are necessarily so dry that very considerable breakage or shattering of the leaf structure takes place during packing, and the 10 If the tobacco contains less moisture than that increase the moisture content of the leaf webshandling of the leaves during the conventional re-drying operation also results'in a material loss due to breakage of the leaves.

With the above and other considerations in mind, it is proposed in accordance with the present invention to provide an improved apparatus for altering the moisture content of tobacco or like material without handling or other physical movement of the material under treatment. More specifically, the primary object of the invention is to provide an apparatus capable of adjusting the moisture content of tobacco when in a tightly packed state to any desired value, and this without unpacking the tobacco, remov ing the hogshead or other container or in any way disturbing or agitating thetobaccoleaves. Although the apparatus of the invention is particularly useful in adjusting the moisture content of packed tobacco, the invention is also applicable to tobacco in a loose or unpacked condition. I

In general, the above and other objects of the invention are carried out by enclosing tobacco, usually in the packed state, in a fluid-tight chamber, altering the moisture content of the tobacco in the chamber at sub-atmospheric pressures, detecting changes in the Weight of the tobacco while under treatment at sub-atmospheric pressures and controlling the amount of moisture addedto or removed from the tobacco in accordance with changes in the weight of tobacco so detected. Thus in dryin packed tobacco in accordance with the invention, the tobacco may be placed within a chamber and evacuated to a sub-atmospheric pressure low enough to cause vaporization and removal of moisture therefrom, and the evacuation may be terminated when the weight of the tobacco has been reduced by such vacuum evaporation to a value indicative of the desired moisture content.

The invention will be best understood by reference to the accompanying drawings in which improved apparatus embodying the invention and suitable for carrying out the process has been diagrammatically illustrated. In the drawings- Figure 1 is a diagrammatic and simplified representation of apparatus suitable for carrying out the moisture adjusting method of the invention;

Figure 2 is an enlarged elevation-of the weighing mechanism disclosed in Figure 1;

Figure 3 is an end view, partly in section, of the mechanism shown in Figure 2;

Figure 4 is an enlarged sectional view. of an electric switch which may be used in the weighing mechanism of Figures 2 and 3; r

Figure 5 is a sectional view of the switch, taken along the lines 5-5 of Figure 4;

Figure 6 is a diagrammatic representation of a modified form of apparatus for carrying out our improved process; and

Figure '7 is an enlarged elevation of the scale mechanism used in the system of Figure 6.

Referring to the drawings and particularly Figure 1, the apparatus there disclosed includes a chamber I of any suitable construction capable of withstanding high fluid pressures without leakage. The chamber disclosed is generally rectangular and is provided with a removable door or closure (not shown) which makes a fluid-tight fit with the chamber.

Any suitable means may be provided for controllably evacuating the chamber I. Although various forms of pumps or other suction devices may be used, it has been found that steam J'et evacuators are Well suited for this purpose. Accordingly, there has been illustrated in the drawings a three stage steam jet evacuator E having its intake connected to a vacuum or suction pipe 3 connected with the interior of the chamber l. A control valve 4 may be provided in the suction pipe 3 if desired. The evacuator illustrated includes a first stage steam jet ejector 5, an intercondenser E, a second stage steam jet ejector I, a second intercondenser 8 and a third stage steam jet ejector 9. The number of stages of steam jet ejectors may be increased or decreased, and the invention is in no way limited to the use of the three stage apparatus illustrated. Since multi-stage steam jet evacuators of the type illustrated are well known in the art, and since the invention is in no way limited to the use of the particular evacuator illustrated, a detailed description of the construction thereof will not be given.

The vacuum or absolute presure within the chamber I is indicated by a suitable gauge I and the temperature by a thermometer I I. Suitable means are provided for admitting air to break the vacuum in the chamber I, and as shown, a pipe I2 passing through the chamber wall and controlled by a manual valve I3 and a solenoid operated valve I4 may be employed for this purpose. The solenoid valve I4 may be of any suitable known construction and operates to close the passage through the vent pipe I2 when the solenoid I5 is deenergized, and to open this passage when this solenoid is energized.

In accordance with the invention, the treatment may comprise either an increase or a decrease in the moisture content of the tobacco or other material under treatment. When a de crease in moisture content is desired, this is accomplished lby evacuating the chamber I to an absolute pressure at which moisture is vaporized and withdrawn from the tobacco. Such vaporization of moisture is accomplished by the absorption of heat, and unless the sensible heat content of the tobacco is initially quite high, it is necessary to supply heat to the tobacco during vacuum evaporation to replace the heat absorbed as latent heat of vaporization. We prefer to supply heat during evacuation by creating an alternating electrostatic field in the tobacco as described in detail and claimed in Patent No. 2,124,012. Since the apparatus for so supplying heat to the tobacco is fully illustrated and described in the patent referred to, it will not be described in detail herein. This apparatus has been diagrammatically illustrated in the drawings as including an oscillator I5 supplied with alternating current from a suitable source I1 through a switch I8. The switch I8 may be manually operated and in accordance with one aspect of the invention, is also provided with a solenoid operating device I9 arranged to open the switch when the solenoid is energized. The output of the oscillator I6 is connected through the leads 2!] to spaced plates or electrodes 2 I within the chamber I. The leads 20 pass through suitable insulating bushings 22 in the chamber walls. The oscillator I6 operates in a known manner to create a high frequency electrostatic field between the plates 2I whereby heat is generated in the tobacco contained in the hogshead 23 disposed in this field as shown.

Suitable means are provided for supplying steam to the chamber I when it is desired to increase the moisture content of the tobacco under treatment. In the illustrated embodiment, a pipe 24 is connected to the chamber and is controlled by suitable means such as a manual valve 25 and a solenoid operated valve 26. Low pressure steam is supplied to the pipe 24 from any suitable source. The valve 25 is arranged. to close the pipe 24 when its solenoid element 21 is energized, and to open when this solenoid is deenergized.

In accordance with one aspect of the invention, the alteration in moisture content of tobacco is controlled by changes in weight of tobacco while under treatment. To this end, apparatus is provided for continuously detecting the weight of the tobacco in the chamber and for indicating its weight at a point outside the chamber. Various means may be used for this purpose. As shown in Figure 1, a vertically movable scale platform 28 is provided within the chamber I, and is supported in any suitable known manner and connected to a beam 29 carried by a fixed pivot or fulcrum 30. The outer end of the beam 29 extends into a compartment 3| forming an extension of the chamber I and engages a vertical rod 32 disposed between a pair of aligned

flexible bellows

33 and 34. The bellows 33 and 34 are respectively sealed to opposite walls of the compartment 3| about oppositely disposed openings in these walls. The rod 32 is connected through the head of the upper bellows 33 to a scale indicating mechanism S which may be of conventional construction as hereinafter described in detail. With the disclosed arrangement, movement of the platform 28 in response to a. change in weight of the tobacco in the hogshead 23 moves the outer end of the beam 29 and s0 raises or lowers the rod 32, thus operating the scale indicating mechanism S to indicate a change in weight of the tobacco. Since both of the oppositely dis posed

flexible bellows

33 and 34 are exposed on one side to the atmosphere and on the other to the pressure in the chamber I, changes in the absolute pressure within the chamber have no effeet on the transmission of movement from the platform 28 to the scale indicating mechanism S, and the scale mechanism moves in response to changes in weight of the tobacco only. It will be understood that various known means other than that shown can be employed to transmit the movement of the platform 28 to the scale indicating mechanism S through the walls of the chamber l.

The method of the present invention may be carried out by manual manipulation of the various valves if desired. It is usually preferable however, to provide mechanism by means of which the movement of the scale indicating mechanism to a position indicative of the desired final moisture content operates the valves and switches which terminate the process. This may be accomplished by suitable electrical control apparatus, energized by the closing of switch mechanism operated when the scale mechanism indicates a. predetermined weight. Various forms of scale operating switches may be used, and one suitable form is shown. in connection with the scale mechanism in Figures 2 through 5.

As shown, particularly in Figure 2, the operating rod-32 is connected to the scale indicating 'mechanism S through a lever 35 carried by a fulcrum 36. A pair of scale beams 3'! and 38, re-

spectively carrying slidable weights 39 and '40,

serve to adjust the mechanism to the desired weight. The scale beams 31 and 38 are fixed to the lever 35 and move therewith about the fulcrum 35. Movement of the lever 35 is transmitted to the scale mechanism S by a rod 4i pivotally connected to the lever 35 at 42. In accordance with conventional practice, the rod H is connected by a flexible strap 43 to an arcuate sector 44 pivoted at 45 to a cross beam 45 and carrying a depending counterweight 41. A sec-- ond arcuate sector 48 is connected by a flexible strap 49 to one side of a fixed frame 50. The cross beam .6 is connected by a spring to a vertically movable rod 52 carrying a rack 53 which engages a pinion 54 on a horizontal scale pointer shaft 55. The scale pointer 56 is fixed to the shaft 55 and travels over a suitable circular scale 51. The described sector and counterweight mechanism is duplicated on the opposite side of the frame 55 in accordance with known practice, but in the drawings, this duplicate mechanism has been omitted to simplify the disclosure.

Various forms of scale operated switches may be employed. In the illustrated embodiment, a switch C of the mercury contact type is used. As best shown in Figure 4, the switch C comprises a sealed envelope 58 of insulating material having a recess 59 containing a pool of mercury 60 at its lower end. One contact SI of the switch is stationary and is permanently immersed in the mercury 60. The other contact 62 is movable about a spring pivot 63 into and out of contact with the mercury in the pool 60. The spring pivot 63 tends to hold the movable contact 62 out of the mercury pool as shown by dotted lines in Figure 4. An armature 64 of magnetic material is fixed to the movable contact 62 by a rod 65 as shown, and is disposed adjacent one wall of the envelope 58. A permanent magnet 66 is carried by an arm 61 fixed to the scale pointer shaft 55. When the shaft 55 turns to a position in which the magnet 66 is opposite the armature 84, the armature is attracted and moves the contact 62 to the position indicated in Figure 4 where it enters the pool of mercury 60 and so closes an elec trical circuit to the fixed contact 6 I. The arm 61 is preferably so disposed that the contacts of the switch C are closed when the scale pointer 56 is at the zero scale position, these contacts being open at all other scale positions.

The envelope 58 of the switch C is preferably movably mounted by suitable means so that its position can be adjusted to provide closing of its contacts at the desired scale position. In the disclosed embodiment, this is accomplished by providing a fixed bracket 68 having an arcuate slot 69 therein for the reception of a pin fixed to the switch envelope 58. An adjusting screw 1|, threadedly engaging an opening in the scale frame 12 is connected to the switch envelope 58 through a ball and socket joint 13. Rotation of the screw 'H by the knob 14 moves the switch envelope 58 to various adjusted positions relative to the switch operating magnet 66.

The steam jet ejectors 5, 1 and 9 of the evacuator E are supplied with high pressure steam from a suitable source through a, pipe 75. The flow of steam through this pipe may be governed by a manually operable valve 16 or a solenoid valve 11. The valve 11 is of a known type which is closed when its solenoid 18 is energized.

The method of the present invention may be carried out in various ways. Assume first that it is desired to reduce the moisture content of a hogshead of tobacco to a predetermined value. and that the operation is to be carried out with manual control. The initial moisture content of the tobacco is determined and the weight of moisture to be removed from the hogshead in order to produce the desired final moisture content is calculated. The hogshead is then placed on the scale platform 28 within the chamber I and the chamber door is closed, the steam supply valve 25 and the vent valve l3 being closed. Assuming that pounds of moisture is to be removed from the tobacco, the

weights

39 and 40 on the scale beams 31 and 38 are adjusted until the pointer 56 registers minus 100 on the scale 51. The evacuator E is then operated by opening the steam supply valve 16 and the absolute pressure within the chamber l is quickly reduced to a value at which moisture contained in the tobacco is vaporized and drawn off through the evacuator. It will be understood that cooling water is admitted to the condensers 6 and 8 while the steam jets 5, 1 and 9 are in operation, and further, that the several steam jets may be operated successively rather than simultaneously if desired.

The vacuum evaporation of water vapor results in the absorption of heat, and the tobacco is accordingly cooled. In cases where any considerable amount of moisture is to be removed, the oscillator 16 is operated by closing the switch l8, and heat is supplied to the tobacco to replace at least some of the heat absorbed as latent heat of vaporization. As moisture is evaporated from the tobacco, the weight of the hogshead drops. When just 100 pounds of moisture has been removed, the pointer 56 registers zero on the scale 57. At this point, the operator cuts off the evacuator E by closing the steam supply valve I6, and vents the chamber I to the atmosphere by opening the vent valve l3, at the same time deenergizing the oscillator it by opening the switch l8. The moisture content of the tobacco is then reduced to the exact value desired, and the tobacco is removed from the chamber for storage, shipment or other disposition.

Considering a case in which the'moisture content of the tobacco is to be increased, the number of pounds of moisture to be added is calculated as before, the hogshead is placed onthe scale platform 28 and the chamber is closed. The

weights

39 and 40 are adjusted until the scale pointer registers the amount of moisture to be added on the plus scale, say plus 100 pounds.

The evacuator is then operated as before until a very high vacuum has been drawn in the chamber. The degree of vacuum should be such as to remove substantially all of the air initially contained in the chamber and in the interstices of the tobacco structure therein. The degree of vacuum required for this purpose varies somewhat with the temperature of the tobacco. With to- .bacco having an initial temperature of about 70 tor E, the vent pipe F. or higher, a vacuum of from 29.5 to 29.6 inches of mercury (.5 to .4 inch of mercury absolute pressure) is sufficient, whereas with lower initial minimum temperatures of the tobacco mass, vacuums as high as 29.85 to 29.95 or, even higher (.15 to .05 inch of mercury absolute pressure or less) may be required. Following this initial evacuation, which is accomplished by admitting steam through the pipe to the jets of the evacuator E, the valve 4 in the suction line 3 is closed and the steam supply valve 25 is opened to permit theflow of steam to the chamber I. The steam so supplied penetrates the tobacco at an increased absolute pressure and condenses on the leaf structure throughout the tobacco mass, thus increasing the moisture content of the tobacco. During the initial evacuation of the tobacco, some moisture contained therein is usually evaporated whereby the tobacco weight is decreased and the scale pointer 56 moves in a counterclockwise direction from the initially set point of plus 100. As the moisture content is increased by the supply of steam to the chamber however, the weight of the tobacco rapidly increases and the pointer 56 moves toward the zero point. When the zero point is reached, the operator cuts off the supply of steam by closing the valve 25 and vents the chamber to atmosphere by opening the valve l3. The steam is supplied to the tobacco at sub-atmospheric pressures whereby the increase in tobacco temperature is limited. In some cases however, the required increase in moisture content is such that the tobacco is heated by the steam to temperatures at which discoloration or other heat deterioration of the tobacco might take place after an interval. In such cases, the supply of steam is continued until the scale pointer 56 has passed the zero point and registers some value on the minus portion of the scale. At this point, the supply of steam is cut off and the evacuator E is again operated to reduce the absolute pressure in the chamber l and cause vacuum vaporization of some of the moisture supplied to the tobacco by the steam. This vacuum vaporization cools the tobacco and at the same time reduces its moisture content. When the reduction in moisture content is such that the scale pointer 56 again registers zero, the operator cuts off the evacuator and vents the chamber 1 to atmosphere, thus terminating the process.

In accordance with the invention, the above described alteration in the moisture content oi the tobacco may be controlled directly in response to the change in the weight of the tobacco to the desired value. For this purpose, the scale operated switch C is connected in a series control circuit to govern the operation of the evacualZ, the oscillator l6 and the steam supply pipe 24. As shown in Figure 1, this circuit includes a source of electrical energy 19, wire 80, the solenoid 18 of the evacuator steam supply valve Tl, wire 8!, switch 82, wire 83, the solenoid H) of the vent valve l4, wire 84, switch 85, wire 86, scale switch C, wire 81, switch 88, wire 89, oscillator switch operating solenoid l9 and wire 90 to the source 19.

In performing our process under the control of the tobacco weight, and for the purpose of reducing the moisture content of the tobacco, the operator first adjusts the

weights

39 and 48 on the scale beams 31 and 38 until the pointer 56 indicates the amount of moisture to be removed, say minus 50 pounds. At this position of the scale pointer 56, the switch C is open as described above, since the scale magnet 66 is moved to a position in which the switch armature G4 is not attracted. Accordingly, the control circuit traced above is deenergized and the evacuator steam supply valve 11 is opened and the vent valve I4 is closed. The operator opens the manual vent valve l3 and the manual steam supply valve 16 and if necessary or desirable, closes the oscillator energizing switch [8. The evacuator E operates to produce a high vacuum in the chamber l and moisture is evaporated from the tobacco, the heat absorbed as latent heat of vaporization being replaced by the heat supplied through the electrostatic field produced in the tobacco by the oscillator Hi. When the weight of the tobacco has been reduced to the desired point, at which the pointer 55 on the scale registers zero, the magnet 66 moves to a position in which it closes the switch C' and the above traced control circuit is energized. This closes the steam supply valve l1, cutting off the evacuator E, opens the vent valve l4 and opens the oscillator energizing switch [8, thus terminating the process.

When moisture is to be added to the tobacco under control of the tobacco weight, the manual switch 88 is moved to its upper position, cutting the oscillator switch operating solenoid l9 out of the control circuit. Also, the switch is moved to the right as shown in Figure 1, connecting the solenoid 21 of the steam supply valve 26 in the control circuit, and the switch 82 is moved to the left, cutting the solenoid 18 out of the control circuit. The

scale weights

39 and 40 having been adjusted to bring the pointer 56 to the desired position, say plus 50 pounds for an addition of 50 pounds of moisture, the operator then opens the manual vent valve l3 (the solenoid operated vent valve I4 is closed) and opens the evacuator steam supply valve 16, thus evacuating the chamber l to the desired low absolute pressure as explained above. The operator then closes the suction line valve 4, closes the evacuator steam supply valve 16 and opens the manual chamber steam supply valve 25. Steam is thus supplied to the previously evacuated tobacco, and sufficient steam is admitted to increase the pressure on the tobacco by a considerable amount, although the pressure is preferably maintained at a sub-atmospheric value. The steam is introduced until the scale pointer 55 registers the zero indication whereupon the switch C is closed. This closes the control circuit, thereby energizing the solenoid 21 and closing the steam supply valve 26 and energizing the solenoid l5 to open the vent valve l4, whereby the process is terminated. If it is necessary or desirable to cool the tobacco after the addition of steam thereto, the initial evacuation of the tobacco and the supply of steam thereto are manually controlled, the switch B8 being moved to the point 9! to open the control circuit. After sufficient steam has been supplied to the tobacco to increase its moisture content to a value appreciably above the desired final value, as indicated by the movement of the pointer 56 past the zero point and to the minus section of the scale, the manual steam supply valve 25 is closed, the manual evacuator steam supply valve 16 is opened and the switch 88 is moved to the point 92, the switch 82 being moved to the right to connect the solenoid 18 in the control circuit. This places the scale switch C in control of the final vacuum evaporation. When the vacuum vaporization of moisture has proceeded to a point where the pointer 56 again reaches the zero indication, the scale switch C is closed, energizing the solenoids I8 and I thereby opening the vent valve l4 and closing the evacuator steam supply valve 11 and the process is ter minated.

When moisture is removed from the tobacco by our process, certain economies can be effected by so controlling the supply of heat to the tobacco that its final temperature after vacuum evaporation of moisture therefrom is not substantially higher than its initial temperature. This may be accomplished by first evacuating the tobacco to a point where vacuum evaporation of the contained moisture therefrom is initiated and then energizing the oscillator l6 and supplying heat to replace that lost as latent heat of vaporization, the evacuation and the supply of heat being simultaneously out 01f as described above when the desired amount of moisture has been removed. This procedure may be carried out under manual or automatic control as described above, the oscillator energizing switch It being closed only after the absolute pressure in the chamber I has been lowered by the evacuator E to a value at which vaporization of contained moisture from the tobacco is initiated.

The same result may be accomplished by initiating the operation of the oscillator either prior to or simultaneously with the start of the evacuator operation and cutting off the oscillator before the vacuum evaporation is discontinued. With this procedure, the.initial operation of the oscillator supplies sensible heat to the tobacco whereby its temperature is raised before the evacuator has lowered the absolute pressure in the chamber to a point where vaporization of contained moisture is initiated. After the absolute pressure is reduced to the point at which moisture is vaporized at the prevailing temperature, the heat absorbed as latent heat of vaporization is replaced by the heat supplied from the electrostatic field created by the oscillator, and the tobacco temperature remains substantially constant as moisture is extracted therefrom. Before the moisture content of the tobacco has been reduced to the desired final value, the oscillator is deenergized and moisture is vaporized without heat supply by continued evacuation with the result that the temperature of the tobacco is lowered to a value at or near its initial value.

The above described procedure may be carried out manually in accordance with the observed changes in the weight of the tobacco, or the moisture extraction can be governed by weight operated control apparatus. Figures 6 and 7 of the drawings illustrate control apparatus suitable for carrying out the moisture reduction process according to this modification of the invention. The apparatus shown in these figures is similar to that illustrated in Figures 1 through 4 and described above. Accordingly, the parts previously described will be designated by like reference characters with distinctive exponents and a repetition of the description of these parts will be avoided.

As shown in Figure 6, the scale indicating mechanism S is provided with two switches C and C. The switch C is connected in a series circuit including the control energy source 19, the solenoid l5 of the vent valve l4 and the solenoid 78 of the evacuator steam supply valve 11'. The switch C" is connected in series with the source 19' and the solenoid IQ of the oscillator energizing switch l8. As best shown in Figure '7, the switch C corresponds to the switch C in the modification of Figures 1 through 4,

that is, the switch C is so disposed as to be closed when the pointer 55' is at the zero indication on the scale 51'. The switcli Cf is adjustably supported ata point to the left of the switch C as viewed in Figure 7 whereby the switch C" is closed before the pointer 56' reaches the zero point when moving from an indication on the minus scale. The switch C" may be adjustably supported by any suitable means, and as shown, is provided with a pin 93 passing through an arcuate slot 94 in a bracket 95 and carrying a block 96 slidable in a vertical slot 91 in a horizontally movable bracket 98. The bracket 98 is slidably carried by the horizontal rods 99 fixed to the scale frame 12. An adjustable screw I00, threaded through an opening in the scale frame 12', is connected to the horizontally movable bracket 98 through a swivel joint lfll. With this arrangement, adjustment of the screw IN by the knob I02 moves the switch C" in an arcuate path about the pointer shaft 55'.

In carrying out the process with the controls illustrated in Figures 6 and '7, the amount of moisture to be removed is determined as before and the scale weights are set so that the pointer 56' indicates the weight of moisture to be removed on the minus scale. The position of the oscillator control switch C" is so adjusted that the deenergization of the oscillator will precede the cutting off of the evacuator by an interval suflicient to permit a reduction of the tobaccotemperature to substantially its initial value by vacuum vaporization of moisture therefrom. The operator simultaneously opens the evacuator steam supply valve 16' and closes the oscillator energizing switch "3. The oscillator sets up an electrostatic field which heats the tobacco and so raises its temperature to a value considerably above its initial temperature and during this heating interval, the evacuator E lowers the absolute pressure in the chamber I to a value at which moisture is vaporized from the tobacco at its then prevailing temperature. This vaporization and removal of moisture decreases the weight of the tobacco until the scale magnet 66' moves adjacent to and closes the switch C". This energizes the solenoid l9- and opens the oscillator energizing switch 18, thereby cleenergizingthe oscillator and so cutting off the supply of heat to the tobacco. After the magnet 66 passes the switch C, this switch again opens, but the oscillator energizing switch 18 remains open because the solenoid l9 cannot close this switch but acts only to open it. The evacuation of the chamber continues until the pointer 56' reaches the zero indication, at which point the moisture content of the tobacco has been reduced to the desired final value. At this point, the scale magnet 66' closes the switch C, energizing the solenoids l5 and 18', thereby closing the evacuator steam supply valve 11' and opening the vent valve It. This operation vents the chamber I to atmosphere and terminates the process by discontinuing the vaporization and removal of moisture from the tobacco. The vacuum vaporization of moisture after the oscillator is deenergized cools the tobacco to a temperature close to its initial temperature and thus insures that substantially all of the heat supplied to the tobacco during the process is utilized in the vacuum vaporization of moisture therefrom,

Although the invention has been described in connection with the adjustment of the moisture content of tobacco, it should be understood that the invention is not limited to moisture adjustment of this product alone.

We claim:

1. Apparatus for altering the moisture content of tobacco or like material comprising a fluid tight chamber, means outside of said chamber for evacuating the same, means including a movable platform within the chamber and weight indicating means outside the chamber operated by said movable platform for weighing the material in the chamber, and means controlled by said weight indicating means for governing the operation of said evacuating means.

2. Apparatus for altering the moisture content of tobacco or like material comprising a fluid tight chamber, means outside of said chamber for evacuating the same, means for supplying steam to said chamber, means including a movable support within the chamber and weight indicating means outside the chamber operated by said movable support for continuously weighing material in said chamber while under vacuum and means operated by said weight indicating means for controlling the operation of said evacuating meansand said steam supplying means.

3. Apparatus for altering the moisture content of tobacco or like material comprising a fluid tight chamber, means for evacuating said chamber, means for supplying steam to said chamber,

means for supplying heat to a mass of tobacco in said chamber, means including a movable platform in said chamber and weight indicating means outside said chamber for continuously detecting the weight of the material in said chamber, means for initiating the operation of said evacuating means, said steam supplying means and said heat supplying means, and means controlled by said weight detecting means for discontinuing the operation of said evacuating means, said steam supplying means and said heat supplying means.

4. Apparatus for altering the moisture content of tobacco or like material comprising a fluid tight chamber, means for evacuating said chamber, means for supplying steam to said chamber, means for creating an electrostatic field in said chamber for supplying heat to a mass of tobacco therein, means including a movable platform in said chamber and weight indicating means outside of said chamber for detecting the weight of the tobacco in said chamber, means for initiating the operation of said evacuating means, said steam supplying means and said electrostatic field creating means, and means controlled by said weight detecting means for discontinuing the operation of said evacuating means, said steam supplying means and said electrostatic field creating means.

5. Apparatus for altering the moisture content of tobacco or like material comprising a fluid tight chamber, means outside of said chamber for evacuating the same, means for venting said chamber to the atmosphere, means for initiating the operation of said evacuating means, means including a movable support'within the chamber and weight indicating means outside the chamber operated by said movable support for continuously detecting changes in the weight of tobacco in said chamber while under vacuum and means controlled by said weight indicating means for discontinuing the operation of said evacuating means and simultaneously opening said chamber venting means.

6. Apparatus for altering the moisture content of tobacco or like material comprising a fluid tight chamber, means outside of said chamber for evacuating the same, means for supplying heat to a mass of tobacco in said chamber, means including a movable support within the chamber and weight indicating means outside the chamber operated by said movable support for continuously detecting changes in the weight of a mass of tobacco in said chamber while under vacuum, means controlled by said weight indicating means for discontinuing the operation of said heat supplying means when the weight of the tobacco has fallen to a predetermined value and means controlled by said weight indicating means for discontinuing the operation of said evacuating means when the weight of the tobacco has fallen to a value lower than said predetermined value.

7. In apparatus for altering the moisture content of tobacco or like ma erial, in combination, a fluid tight chamber, mea for evacuating said chamber, a movable scale platform within said chamber, Weight indicating mechanism outside of said chamber, and means for transmitting movement from said platform to said indicating means comprising a pair of oppositely disposed substantially aligned openings in said chamber, fluid tight flexible sealing means secured across said openings, means for simultaneously moving said flexible means in accordance with the movement of said scale platform, and means for transmitting such movement from said flexible means to said weight indicating means.

8. In apparatus for altering the moisture content of tobacco or like material, in combination, a fluid tight chamber, means for evacuating said chamber, a movable scale platform within said chamber, weight indicating mechanism outside of said chamber, and means for transmitting movement from said platform to said indicating means comprising a pair of fluid tight flexible bellows respectively secured over oppositely disposed and substantially aligned openings in said chamber, means for simultaneously moving said bellows in accordance with movements of said scale platform, and means for transmitting such movement from said flexible bellows to said weight indicating means.

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