US1593890A - Apparatus for drying and the like - Google Patents

Description

July 21, 1 26. 1,593,890

.L WELCH APPARATUS FOR DRYING AND THE LIKE Filed Feb. 17 1925 4 INVENTOR 65 04. 65.6i0lu swm w :n'o RNEYS Patented July 27', 1926.

UNITED STATES PATENT o iuucE. v

JOHN BEBCEMAN WELCH, OF NEW ORLEANS, LOUISIANA, ASSIGNOB TO WELCHDRY KILN GOKIANY, OF NEW ORLEANS, LOUISIANA, A CORPORATION 01' MISSOURI.

arrana'rus ron DRYING Ann was LIKE.

Application filed February 17, 1925. Serial No. 9,768.

This invention relates to apparatus for drying and the like. Particularly, the 1nvention relates to apparatus for drying ment operation.

. apparatus for treating materials requiring progressively different conditions of an operating medium as the material being treated undergoes characteristic changes in the course of the treatment operation, in which the condition of such operating medium is automatically controlled in response to the characteristic changes ina representative sample of the material being treated so as to progressively establish and maintain the different conditions of such operating medium required in the course of the treatment operation. As applied to drying apparatus, the invention aims to provide an improved apparatus for drying materials, such as lumber or wood, in which the temperature or humidity or both of the drying medium are automatically controlled in response to changes in a varying characteristic (such as weight or moisture content) of the material being dried as the drying progresses.

The improved" apparatus of the inventionis especially adapted for the drying of lumber'or wood, and on this account the invention will hereinafter be more particular- 1y. described as applied to that industry. It is to be understood-however, that the improved apparatus of the invention is applicable to the drying or treatment of other materials where progressively difierent conditions of an operating medium are required as the material being treated undergoes characteristic changes as a result of the treatment operation.

has for its object the prois especially adapted for carrying out the method of dryin lumber, wood, and the like, described an claimed in my copendin application for Letters Patent of the Unite States filed May 24, 1924, Serial No.1715,516. The controlling factors in the drying of lumber and of wood generally are the moisture content of the wood, the thickness of the wood and the species. Woods that are easily subject to splitting in drying must be treated at low tem erature and high humid- 'ity. If the wood as a high percentage of moisture the startin tem erature must be lower and the humi ity higher than if the the same wood had' been air-dried down to a low moisture content before being placed in the drying kiln. In other words, the moisture content of the wood is the controlling factor for any particular thickness and species.

ture content of the wood is first determined and the appropriate temperature and humidity of the drying medium for that moisture content are thereby established. After the wood has been dried down to a lower moisture content more severe conditions of temperature and humidity of the drying me Heretofore, in the dium are allowable.

In the careful drying of wood, the moiscareful, drying of wood, it has been neces sary for theoperator to periodically go into the kiln, take a sample of the wood undergoingdrying and make a moisture determmation of that sample in order to find out if the. moisture content is low enough to perunit or warrant a new setting of theconditions of temperature and humidity. In practice, this necessitates daily weighin'g of propriate conditions for the drying operations. Often, even in the hands of a skillful operator, the drying proceeds too far be fore conditions, are changed and thenagain conditions are sometimes changed before the lumber or wood is dry enough to stand the altered conditions of temperature and humidity.

The high temperatures and humidity within a lumber drying kiln make the duty samples from each kiln to determine the apof entering the" kiln for obtaining sam les most arduous and on this account the ry- I ing is seldom controlled by the moisture con- The improved apparatus of the inventiontent of the wood as it should but is more often based on a time schedule. This schedule is set after the moisture content of the wood is determined and before drying commences. If everything proceeds without interruption, good drying may be accomplished. However, any interruptions in the drying, such as low steam ressure, shutting down of the kilns or bollers for repairs, changes in weather conditions which affect the temperature within the kiln, and a variet of other causes often slow up the actual drying so that the lumber or wood is not able to stand the increasing temperature and decreasing humidity called for by the drying time schedule. As a result, there is often a considerable loss of lumber due to splitting caused by too rapid drying.

In the improved apparatus of the present invention, a representative sample of the material being treated indicates or automaticall prescribes the appropriate difierent con itions of the operating medium required in the course of the treatment opera-' tion. Thus, the re resentative sample is operatively associate with appropriate control means for producing an action indicative of the characteristic changes (such, for

. example, as changes in weight or moisture content) in the-representative sample as the treatment operation progresses. This action, in the improved apparatus of the invention, regulates the pressure in a fluid pressure system or compressed air equipment in such mannerv that the pressure 1n, the system varies in res onse to said characteristic changes and 1s accordingly indicative of such characteristic changes. The pressure in the system then actuates an appropriate indicator or appro riate controlling instrumentalities for esta lishing and maintaining different desired conditions of the o rating mediums, such, for example, as di erent conditions of tem erature or humidity or both within a lum er-dryin kiln. In one of its aspects, the improved apparatus of the invention comprises a control means within the drying apparatus and responsive to characteristic changes in a representative sample of the material being dried in com bination with a fluid pressure system for transmitting the action of the control means lar to the humidity helical coil described below).

The apparatus illustratedin the drawing is particularly adapted for controlling the conditions of temperature and humidity within a lumber drying kiln, and 'is shown in the drawing as applied to that purpose. One of the walls. of the kiln is represented by reference numeral 4, and it is to be understood that the apparatus shown in the drawing above this wall is located within the kiln while the apparatus shown in the drawing belowthis wall is located outside the kiln. i 4

The kiln is provided with heating pipes adapted to be supplied with steam from a steam main 5. A compressed air operated valve 6 is included in the steam main 5 and isadapted'to be manipulated by the automatic temperature controlling instrumentalities hereinafter described. The kiln is further provided with a spray system 7 in the supply pipe of which is positioned a compressed air operated valve 8. The kiln is further provided with a damper 9 arranged to be manipulated by the compressed air 0 erated valve 10. The spray valve- 8 and amper valve 10 are actuated'by the automatic humidity controlling instrumentalities hereinafter described.

. A representative sample 11 of the lumber (or other material) to be dried is appropriately associated with a'special type of scales or balancing device operatively mounted within the kiln. The sample 11 is prefer-v ably so positioned that the action thereon of the drying medium within the kiln is fairly representative of the action of that medium throughout the kiln. In the drying of lumher, the sample 11 may conveniently be approximately 8 inches wide, 24 inches long and the average thickness of the lumber undergoing drying.

' The scales or balancingdevice of the improved apparatus of the invention comprises a balance beam or arm 12 operatively supported by a pair of knife edge pivots 13, oneon each side of the beam. The seats or rests of the pivots 13 are formed in posts 14 extending upwardly from a hollow semispherical casing 15.

A carrier 16 is movably mounted on the right-hand side of the beam 12, as viewed in the drawing. The carrier has a depending hook adapted to engage a hook 17 screwed or otherwise secured to the sample 11, whereby the sample is supported by and movable with the carrier. A- weight 18 is operatively associated with the left-hand side of the beam 12, as viewed in the drawing,

and is designed to exactly counterbalance the carrier 16. To this end, the carrier 16 and weight 18 are preferably of exactly the same weight and scales 16' and 18 are operatively associated with these elements so that when the elements occupy corresponding positions with respect to these scales the beam 12 is exactly balanced so far as these elements are concerned. A counterbalance 19 is operatively associated with the left-hand side of the beam 12, as viewed in the drawing, for balancing the beam.

The fluid pressure system of the improved apparatus of the invention comprises an automatic regulator mounted within the easing 15, operated by compressed air, or other appropriate elastic fluid, and controlled by the weight of the sample of material (11) being dried, the initial moisture content of which is known but the size and weight of the sample being capable of variation within reasonable limits. The automatic regulator functions in such a way as to maintain at all times in a pipe or line 20 (outside the kiln) a pressure corresponding quantitatively to the percent of moisture in the sample 11. The variations in pressure in the line 20 are then used to actuate an indicator or to actuate appropriate automatic controlling instrumentalities, or both, as desired.

The casing 15 is pivoted at 21 to a substantially horizontal arm 22. The arm 22 is carried by a vertically disposed screw 23 and vertically disposed guide post 24. The screw 23 and post 24 are mounted between the arms of a U-shaped bracket 25 provided with a lower supporting extension 26 and an upper adjustable supporting extension 27. An adjusting screw 28, cooperating with the bracket 25 and supporting extension 27, permits leveling ofthe arm 22 and scale beam 12. The screw 23 permits adjustment of the height of the arm 22 and scale beam 12. The supporting extensions 26 and 27 are appropriately secured to the stack of lumber 29 piled within the kiln for drying. By turning the casing 15, and hence the scale beam 12, about the pivot 21, the sample 11 can be swung inside of the lumber pile where it encounters substantially the same average drying influences as the lumber itself.

A circular diaphragm 30 of rubber, or other appropriate material, is operatively associated with the casing 15 and carries a centrally positioned knife edge 31 upon which operatively rests the right-hand side (as viewed in the drawing) of the scale beam 12. A valve support 32 is secured to the underside of the diaphragm 30 and is 'freelymovable with the diaphragm, being guided by a pin 33 fitting in an appropriate opening in the bottom of the casing 15. The support 32 carries the movable element 34 of a ball valve, the stationary element of the ball valve being the inner open end of a pipe 35 extending through the casing 15.

.The pipe 35 is connected by a flexible tube 36 with a compressed air supply pipe 37,

The gauge 42 is outside the kiln. The compressed air supend, through a coupling 44, with the interiorof the chamber 15, and at its other end is operatively connected to a reservoir 45 containing compressed air and also a liquid. A bleeder pipe 46 communicates with the flexible tube 43 and extends through the kiln wall 4 and is provided with a valve 47 outside the kiln whereby the compressed air within the casing 15 of the automatic com pressed air regulator can-be appropriately bled out from without the kiln.

The liquid in the reservoir 45 fills the pipe or line 20 and the metal diaphragm 48, of the bellows t pe as shown in the drawing. Expansion 0 the diaphragm 48 is opposed by a spring 49. Expansion and contraction of the diaphragm 48 is transmitted to a pivoted sector-shaped rack 50'through a rod 51 and link 52. A pinion 53 meshes with the rack 50. A combined electric contact and pointer 54 is secured to the pinion 53 and is adapted to sweep over and alternately engage two series of stationary electric contacts 55 and 56. A scale or dial 57 is as sociated with the pointer 54 and is graduated in percentage moisture from 0% to 200%.

The movable contact pointer 54 is electrically connected bya conductor 58 to a terminal or binding post 59 and thence by a conductor 60 to one contact of a switch 61. The stationary contacts 55 are electrically connected together and to a terminal or b ndlng post 62. The contacts 56 are similarly connected together and to a bindmay post 63. A conductor 64 connects the binding post 62 to a stationary contact 65.v and similarly the terminal 63 is connected by a conductor 66 to a stationary contact 67.

- The switch 61 is connected through a I it battery 68, or other appropriate wurce of" no a lee

with the-gear 74 and has a substantially semi-circular contact element of such configuration that it is always in engagement with either one or the other of the contacts 65 and 67 and in two positions of each revolution engages both of the contacts 65 and 67.

The contact 75 carries two diametrically positioned pins 76 adapted (in consequence of the rotation of the contact 75) to alternately engage the teeth of a star Wheel 77. A temperature-adjusting cam 78 is secured to the star wheel 77, and similarly a humidity-adjusting cam (not shown) is also secured to the star wheel.

The movable contact 75 is electrically grounded at 120. The contacting element of thestationary contacts 65 and 67 is preferably a pair of-resilient spaced contact springs between which the contacting element of the movable contact 75 passes, as in the well-known electric knife switches.

The contacts 65 and 67, the star wheel 77 and associated elements are preferably combined and mounted in a single instrument case indicated generally by reference character 79 in the drawings.

A cam lever arm 80 is associated with the cam 78 and is operatively connected to a temperature-setting means or pointer 81. It will be understood that movement of the lever 80 is ap ropriately transmitted to the pointer 81. imilarly, a humidity-setting means or pointer 82 is operatively connected to and adapted to be actuated by the humidity-adjusting cam secured to the star wheel 77 not shown in the accompanying drawing for the sake of simplicity.

A du lex valve mechanism is mounted within the case 79 of the combined temperature and humidity controller illustrated in the accompanying drawing. This mechanism comprises a temperature control VJlXB having a valve chamber 83 which communicates by a passage 84 with a compressed .air supply pipe 85. The valve chamber 83 contains a valve head 86 adapted to open or close a ort 87 to the atmosphere and simultaneous y to close or open (respectively) the passage 84. The valve head 86 is carried by a hollow valve stem 88 providing communication between the valve chamber 83 and a bellows diaphragm 89. The diaphragm 89 communicates by a flexible tubing 90 with an air nozzle 91 mounted upon the temperature-setting pointer 81. A flapper valve 92 is mounted upon a tempera hire-indicating pointer 93 so as to close the air nozzle 91 as the temperature-indicating pointer 93 movesinto a predetermined position with respect to the temperature-setting pointer 81. An air pipe 94 provides communication between the valve chamber 83 and the air operated steam valve 6.

- The humidity control valve is of similar construction to the temperature control valve and comprises a valve chamber 95 having a passage 96 connected to the air supply pipe 85. A valve head 97 is adapted 1 ,oeaeeo tubing 101 with an air nozzle 102 mounted on the humidity setting ointer 82. A. flafpper valve 103 is mounte on. a humidityin icating pointer 104 so as to closethe air nozzle 102 as the. humidity-indicating pointer 104 approaches within a predetermined distance of the humidity-setting pointer 82. An air pipe 105 communicates between the valve chamber 95 and the air operated spray valve 8. The air pipe v105 also communicates with the damper valve 10 for opening or closing the damper 9.

The air pipes 85, 94 and 105 are provided with pressure gauges 106 to indicate the air pressure in these lines.

The temperature indicating pointer 93 is actuated by a temperature element or dry pulp 108, while the humidity indicating pointer 104 is actuated by a we t bulb 107. The temperature element or dry bulb 108 is of the usual type, containing a volatile liquid which, when subjected to heat, volatilizes and the resulting vapor pressure is transmitted. through a flexible tube 113 to a helical coil 110. The movement of the helical coil 110 is transmitted to the tempera ture indicating pointer 93 by means of links 111 and 112. The humidity-indicating pointer 104 is actuated in like manner by the wet bulb 107 through the flexible tube 109, helical coil 114 and the links 115 and 116.

The operation of the apparatus is substantially as follo-ws. The initial moisture content in percent of the representative sample 11 is first determined. This may conveniently be done by the autocalculator, a device for directly measuring or indicating the moisture content of a sample of lumber. The hook 17 having been ap propriately secured to the sam le 11, is then used to suspend the sample rom the carrier 16. The carrier 16 and weight 18 are then correspondingly moved along their respective beams until the indicating gauge 42 registers the percent of moisture-contained in the sample. The sample 11 need not be of any articular weight, it only being necessary t at its weight be within the range of the control scales. In other words, the exact weight of the sample need not be known, but the moisture content of the sample must be known. The carrier 16 and weight 18 will occupy corresponding positions with respect to their cooperating scales 16' and 18', respectively. Under such circumstances, the weight of the carrier is al- .cause the ways exactly counterbalanced by the weight 18.

For purposes of explanation, let us assume that the sample 11 is found to have a moisture content of 80%. This means that the lumber to be dried has a moisturecontent of approximately 80%. Thecarrier 16, with the suspended sample 11, is then moved along the scale beam until the gauge 42 registers 80%, it being understood, of course, that the weight 18 is simultaneously moved with the carrier 16 to its appro riate counterbalancingposition. Therea r (as the moisture content of the sample 11 decreases in the course of the drying operation) the pressure gauge 42, as well as the positlon of the pointer 54 with respect to the scale 57, will directly indicate the actual percentage moisture content of the sample 11.

Air, or other appropriate elastic fluid, is supplied at constant pressure through the pipes 36 and 37 to the interior of the cas ng 15. The pressure within the casing rises until the pressure on the bottom of t e diaphragm 30 is just slightly in excess of the pressure-on the to of the diaphragm due to the resting of t e scale beam 12 on the knife edge 31, whereu on the diaphragm slightly lifts the movab e element 34 of the ball valve and the supply of air to the interior of the-casing 15 is thereby interrupted by the closing of the ball valve. Air escapes from the interior of the casing 15 through the bleed valves 41 and 47, appropriately adjusted, and the air pressure within the casing thereupon becomes so lowered that the ball valve opens and com ressed air again enters the casing from t e pi s 36 and 37. Actually, the ball valve wil open just enough to permit the air to enter the casing 15 at such a rate as to keep the pressure within the casing just suflicient to balance the weight of the sample 11, whereby the scale beam 12 is always maintained in balance, and the air pressure within the casing 15 is always directly proportional to the moisture content of the sample 11.

In other "words, as the representative sam 1e 11 decreases in weight, in the course of te drying operation, the pressure within the'system automatically becomes less, be-

pressure at the knife edge 31 is less, allowing a lighter pressure operating against the diaphragm 30 to seat the ball valve 34. In order to allow the escape of the ex:ess pressure, the valve 41 allows the air to bleed through the pipe 40, and/or the valve 47 allows the air to bleed through the pipe 46, so ,that' the air pressure within the regulator casing 15 always corresponds toa definite weight or pressure applied at the knife ed 31.

Accor ingly, the ressuregauge 42, Within the kiln, and t e indicator (5457), without the kiln,.each directly registers the perature controller and the actual ll as t e drying operation progresses. If desired, the readings of the indicator 54-57 may be employed as a guide for the manual adjustment 'of the temperature and humidity setting instrumentalities. In pther Words, the operator obtains from the indi-' cator the actual moisture content of the rcentage moisture of the sample lumber being dried as the drying operation-- progresses and he sets or ad'usts the temumidity controller to establish and maintain the desired different conditions of temperature and humidity within the kiln prescribed by the drying schedule. In the improved apparatus of the invention, in its complete form, the indicator 54-57 automatically sets or adjusts the controlling instrumentalities for establishing and maintaining the prescribed ment with the contact 65 and the electric motor 69 will be energized through the circuit 62-64657 5+-groundemotor68- 61605958'5455. /The motor will thereupon operate to turn the gear 74 and contact 75 through one-half revolution, whenvthe contact 5 will move out of engagement with the contact 65, but not until the contact 75 has moved into engagement with the contact 67. As the drying progresses, the pointer 54 moves from engagement with one of the contacts 55 into engagement with-the next adjacent contact 56,

whereupon the electric motor is energized and the carrier 74 and contact 75 turned throughhalf a revolution. This sequence of operations is repeated throughout the entire dr in o ration.

ac time the electric motor 69 is ener-' gized, one of the pins 76 engages in a tooth of the star wheel 77 and turns the star wheel through a predetermined angle. This. movement of the star wheel is transmitted to the lie temperature-adjusting cam78 and to the humidity-adjustin'g cam (not shown). In this manner, the temperature-setting pointer 81 is moved a predetermined prescribed amount as a result of its 0 rative connection with the cam lever 80 eac time the electric motor 69 is energized. Likewise the humidity-setting pointer 82 is moved apredetermined prescribed amounteach time the motor is energized.

The star wheel that is, through the same'angle each time the motor 69 is energized. The temperature-adiao 77 is moved uniformly,

87 and opens the passage 84, the air supply through pipe 85 is in direct communication It 1s with the air pipe 94, thereby rmitting compressed air to pass into the pipe 94 and open the steam valve 6, whereupon steam enters the heating pipes within the kiln. So long as the temperature within the kiln remains lower than the predetermined temperature prescribed by the position of the temperature-setting pointer 81, the valve 6 will remain open. As the temperature within the kiln rises (due to the open steam valve 6), the temperature-indicating pointer 93 moves towards the temperature-setting pointer 81 until the temperature within the kiln reaches the predetermined prescribed temperature, whereupon the flapper valve 92 engages and closes the air nozzle 91. This causes the air pressure to be thrown back into the bellows diaphragm 89, which thereupon expands and moves the valve head 86 to close the passage 84, thereby permitting the compressed air in the pipe 94 and steam valve 6 to escape to the atmosphere through the port 87 in the valve chamber 83. The

steam valve 6 thereupon'closes and shuts off the steam supply to the kiln. When the temperature within the kiln has again fallen to below the predetermined prescribed temperature, the temperature-indicating pointer 93 will moveaway from the temperature. setting pointer) 81, causing disengagementbetween the nozzle 91 and the flapper valve '-within the kiln.

92.- The bellows diaphragm 89 will then contract and permit the valve head 86 to return to its original position, whereupon the steam valve 6 is again opened by the action of the compressed air in the pipe 94.

In, a similar manner, when the humidity within the kiln falls below the predetermined prescribed condition, the humidity-in icating pointer 104 will move towards the humidity setting pointer 82 until the flapper valve 108 closes the air nozzle 102., This causes the escape of the compressed air in the pipe 105 and the attendant appropriate manipulation of the spray valve 8 and damper valve 10 for increasing the humidity As the drying operation progresses, the moisture content of the material being dried becomes lower and more severe conditions of temperature and humidity become possible. The loss in weight of the representative sample 11 sets in action the controlling means and instrumentalities that establish and maintain these different and more severe conditions of temperature and humidity.

Any appropriate or desired schedule of temperature and humidity conditions may be established and maintained within the kiln.

by em loying a tem erature-ad'ust' cam (47) 251d a humidity -adjustingcam f the proper designs.

In the apparatus illustrated in the drawing, the temperature-setting pointer 81 is adjustably connected to the cam lever arm such a manner that by turning the rod 118 the relative positions of the cam arm 80 and pointer 81 are appropriately adjusted. A sprin 119 is secured to the arm 117 and holds t e cam-follower of the arm 80 against the cam 78.

An appropriate scale may, if desired, be associated with the star wheel 77 whereby the moisture content of'the representative sample '11 can be directly read at any time durin the drying operation. This is possible d) wheel 77 is directly proportional to the. loss in moisture of the representative sample. By thismeans the moisture content of the material being dried can be accurately indicated wherever the controlling instru mentalities'are located which may, of be remote from the kiln itself.

The improved apparatus of the invention is mechanically simple in construction and accurate in operationf Of the parts neces course,

ecause the movement of the star" I sarily positioned within the kiln, there are only two points of .operatin contact, namely, the knife edges 13 emf 31.. The parts of the apparatus which must be mounted within t e kiln are constructed and arranged insuch a' manner that substantially no injury is caused them by the hot gases and moisture within the kiln. .The fluid pressure systemof the apparatus is accurately and eifectivel controlled by the bal-' ancing device, so t at the pressure in the system changes in response to chan s in weight of the sample 11. Thus, the c ange or loss in weight of the sample-11, as the drying progresses, produces an action (pres sure of thebeam 12 on. knife edge 31) that influences the regulator of the fluid pressure system to efl'ect corresponding changes in t 1 e pressure in the system, And the changes of pressure in the system actuate the temperature or humidity or both controllers, or appropriate indicators, as desired.

While I have described and illustrated an apparatus embodying a combined temperature and humidity controller in a single casing or instrument, it will bereadily understood by those skilled in the art that the princi les of the invention are equally applicab e to an a paratus embodyin a temperature control er alone or ahumid troller alone, or an inde endent temperature controller and an in ependent humidity controller.

While the embodiment of the invention herein described andillustrated is especially suited for the dryin of lumber or wood, it will be understood y those skilFedin the art that this particular embodiment of the invention is equally well adapted for use in 1 "the drying of other materials requiring different conditions of temperature or humidity or both in the course of the drying oper ation. Furthermore, the-principles of the invention are applicable to many industries and uses where difl'erent conditions of one or more operating 'media are required in the course of a treatment operation. Thus, in many manufacturing processes, different 4 conditions ofoneor more operating media trating and bodiment thereof but various modifications are necessary as certain characteristic changes are encountered and the apparatus of t e invention may advantageously be employed to automatically establish and maintain such different operating conditions in response to such characteristic chan s. I have e lained my invention by ilusdescribing a certain specific emof the details of construction and arrangement of'plrts in this embodiment of the invention will present themselves to those '1. The combination having temperature varying means and a "controller codperating therewith for mainskilled in the art. I, accordingly, do not wish to be restricted to theparticular form or construction disclosed herein by way of example for the pur c of setting forthmy invention in accor ance with the patent statutes. The terms of the appended claims I are,

-mam disclosed 1 .all' changes and modifications within spirit and scope of the invention.- H

therefore not restricted to the precise but are intended to cover the I claim: a

in a drying apparatus taining any esired condition of tempera ture within the apparatus, of a fluid pressure system,-contro means adapted to vary the ressure within said system response.

to c anges .in weight of a representative sample of the material being dried as the drying operation progresses, and means responsive to the pressure in said s stem for adjusting said controller to maihtain predetermined different conditions of tem perature within the drying apparatus as the dryi operation progremea e combination in a dryingappara'tus ity con- I 'midity varying means an sure that the troller cooperating therewith for maintaining any desired condition of humidity within the apparatus, of a fluid pressure system, control means adapted to vary the pressure within said system in response to changes in weight of a representative sam le of the material being dried as the drying operation progresses, and means responsive to the pressure in said system for adjustin said controller to maintain predetermine difi'erent conditions of humidity within the drying apparatus as the drying operation progresses.

3. The combination in a drying apparatus having temperature varyin' means and hucontrollers cooperating therewith for maintaining any desired conditions of temperature .and humidity within the appartus, of a fluid pres- .suresystern, control means adapted to vary having humidity varying means and a conthe pressure within said system in response to changes in Wei ht of a re resentative sample of the material being ried as the drying-operation progresses, and means responsive to the pressure in said system for adjusting said controllers to maintain predetermined difierent conditions of temperature and humidity within the drying apparatus as the drying operation progresses;

4.- The combinationin a dryin apparatus, of a fluid pressure system inclu ing a regu- 5. 1m a dryng apparatus, means for producing an action indicative of the loss in weight, of a representative sample of the material undergoing drying, means for causing said action to so control a fluid; respressure is indicative o the changes in weight of said sam lo and indicating means actuated by sai fluid pressure.

later for controlling the pressure therein, a

control means within said apparatus opera-- 6 6. In a drying apparatus, means for producing an action indicative of the loss in .weight of a representative sample of the material undergoing drying, means for causing said action to'so control a 'fluid ressure that the pressure is indicative o" the changes in weight of said sample, and controlling instrumentalities adapted to be adiusted by said fluid pressure so as to estabish. and maintain1 'difl'erent operating conditions within the drying apparatus as saidrepresentative sample changes in weight.

. The combination a rying apparatus having temperature varying means and a controller cooperating therewith for maintaining any desired condition of temperature within the apparatus, of a fluid pressure system including a regulator for controlling the pressure therein, control means including a balancing device'responsive to changes in weight of a representative sample of the ing any desired condition of humidity within the apparatus, of a fluid pressure system including a regulator for controlling the pressure therein, control means including a balancing device responsive to changes in' weight of a representative sample of the material being dried as the drying operation progresses, said control means and said regulator being operatively so connected that changes in weight of said sample influence said regulator to effect corresponding changes in the pressure in said system, and means responsive to the pressure in said system for adjusting said controller to maintain predetermined different conditions of I humidity within the drying apparatus as the drying operation progresses.

9. The combination in a drying apparatus having temperature varying means and humidity varying means and controllers cooperating therewith for maintaining any desired conditions of temperature and humidity withinthe apparatus, of a fluid pressure system including a regulator for controlling the pressure therein, control means including a balancingdevice responsive to changes in weight of a representative sample of the material being dried as the drying operation progresses, said control means and said regulator being operatively so con nected that changes in weight of said sample influence said regulator to effect corresponding changes in the pressure in said system, and means responsive to the pressure in said system for adjusting said controller to main- I tain predetermined different conditions of temperature and humidity within the drying apparatus as the drying operation progresses.

10. The combination in a drying apparatus, of a fluid pressure system including a regulator for controlling the pressure therein, control means including a balancing device responsive to changes in weight of a representative sample of the material being dried as the drying operation progresses,.

to be adjusted so as to establishand maintain different conditions of temperature within the apparatus, a fluid pressure system, control means adapted to vary the pres-- sure in said system in response to changes in weight of a representative sample of the material being dried as the drying operation progresses, and means whereby the pressure in said system actuates said controlling instrumentalities.

12. In a drying apparatus, the combination of controlling instrumentalities adapted to be adjusted so as to establish and maintain different conditions of humidity within the apparatus, a fluid pressure system, control means adapted to vary the pressure in said system in response to changes in weight of a representative sample of the material being dried as the drying operation progresses, and means whereby the pressurein said system actuates said controlling instrumentalities.

13. In a drying apparatus, the combination of controlling instrumentalities adapted to be adjusted so as to establish and maintain different conditions of temperature and humidity within the apparatus, a fluid' pressure system, control means adapted to vary the pressure in said system in response to changes in weight of a representative 7 sample of the material being dried as the drying operation progresses, and means whereby the pressure in said system actuates said controlling instrumentalities.

14. In an. apparatus for the treatment of materials requiring progressively difierent conditions of an operating medium as the material being treated undergoes characteristic changes in the course of the treatment operation, the combination of means for producing within the apparatus an action indicative of said characteristic changes in a representative sample of the material being treated, means for causing said action to so control a fluid pressure, that the pressure is indicative of said characteristic changes in said sample, and indicating means outside the apparatus actuated-by said fluid pressure.

15. Inan apparatus for the treatment of materials requiring progressively different conditions of an operating medium as the material being treated undergoes characteristic changes in the course of the treatment operation, the combination of controlling instrumentalities adapted to be adjusted so as to establish and maintain difierent conditions of said operating medium, means including a fluid pressure responsive to said characteristic changes in a representative sample of the material bein treated, and means actuated by said fiui pressure for adjusting said controlling instrumentalities to rogressively establish and maintain the di erent conditions of said operating medium required in the course of the treatment operation.

16. In'an apparatus for the treatment of materials reguiring progressively different conditions 0 an operating medlum as the material being treated undergoes characteristic changes in the course of the treatment operation, the combination of controlling instrumentalities adapted to be adjusted so as to establish and maintain different conditions of said operating medium, a fluid pressure system, control means responsive to characteristic changes in a representative sample of the material under-v oing treatment for regulating the pressure 1n said system, and means whereby the pressure in said system actuates said controllin instrumentalities.

1 In an apparatus forthe treatment of materials re uiring progressively diflerent conditions 0% an operating medium as the material being treated undergoes characteristic changes in the course of the treatment operation, the combination of controlling instrumentalities adapted to be adjusted so as toestablish and maintain different conditions of said operating medium,

a fluid pressure system including a regu lator for controllin the pressure therein, control means inclu ing a balancing device responsive to said characteristic changes in a representative sample of the material being treated, said control means and said regulator being operativel so connected that said characteristic c anges in said sample influence said regulator to effect corresponding changes in the pressure in said system, and means responslve to the pressure in said system for adjusting said controlling instrumentalities to rogressively establish and maintain the di erent conditions of said operating medium required in the course of the treatment operation.'

18. In an apparatus for the treatment of materials regulrin'g progressively difierent conditions 0 an operating medium as the material being treated undergoes charac resentative sample of the material being treated, said control means and said re ulator-being operatively so connected t at said characteristic changes in said sample influence said regulator to efiect correspondmg changes in the pressure in said system, and indicating means actuated by the pressure in said system.

19. In an apparatus for the treatment of materials requiring progressively different conditions of an operatin medium as the material beingtreated un er oes characteristic changes in the course 0 the treatment operation, the combination of a fluid pressure system including a re controllin the ressure therein, control means'wit in sai apparatus operatively associated with said regulator and responsive to said characteristic changes in a representative sample of the material being gulator for treated whereby said characteristic changes produce correspondin changes in pressure in said system, and indicating means outside the apparatus actuated by the pressure in said system.

In testimony whereof I aflix my signature. V

JOHN BERQHMAN wnncn)

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