US2352220A - Dehydrating machine - Google Patents

Description

June ,27, 1944.

' DEYDRATING MACHINE Filed- Nov. 28, 1941I 4 Sheets-Sheet 1` FTE ` y emv ovfRro/v G. ovl-:RToN 4 2,352,226"

June 27, 1944. G. OVERTON DEHYDRATING MACHIN `Filed Nov. 28, 1941 4 snets-sheet 2 .D m t Q m QR .QN v E O y l m @wil R Q mb, D RJ g 'N 2 F---------------,.M,. o 3 Q G un n. L @l N N NK l IAN, un... v Dm. A hw N i-wml". l 2,

June 27, 1944. s. OVERTON h DEHYDRATING MACHINE Filed Nov. 28, 1941 4 Sheets-Sheet 3 l/E' E EN Ovm ro/v June. 27, 1944.

DEHYDRATlQNG MACHINE Filed Nov. 28, 1941 G. OVERTON :2i-352,220

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Arai ori-'ICE DEBYDRATING MAC Glen Overton,

Dowagiac, Mich., assigner Louisville Drying Machinery This invention relates .to dehydrating machines and is directed more particularly to apparatus for removing dried sheets or iilms from that type of machine in which the material to be dried is spread in relatively thin film form on a heated rotating drum.

In vthe past several diiilculties have been encountered when heat decomposableslurries, solutions and the like were dried on drum driers.

One of the most important of these difiiculties concerns the overheating and cooking of the material treated due to the presence of residual heat in the material after the drying operation has been completed. For example, in the treatment of distillery slops, which have a'high sugar content, it is found that after the dehydrating operation had been completed this residual heat continues to cook the material with the result that caramelizing sets in. In effect, this action of residual heat upon the material which has been dried often changes the characteristics of the material detrimentally to render it relatively useless for the purpose for which it is subseouently intended rand often renders it hard to handle.

Still another difficulty which is encountered in the use of machines of the above character concerns the problem of removing the iilm from the drying drum when the drying operation has been completed. In order that machines of the above character operate with maximum eiiiciency and dehydrate the greatest amount of material possible in a given period of time, it is necessary that the dried film be removed quickly and cleanly so that the surface of the drum is ready to again have a moist film applied to it.

to Company, a corthe drying apparatus toward a conveyor to avoid rolling over or balling up on the drum.

Another object of theinvention is to provide a new and improved doctor blade and doctor blade assembly for a drum drier.

Still another object of the invention is to provide a new and improved apron and apron assembly for a drum drier.

A further object of the invention is to provide an apparatus of the above character wherein the progression of the dried iilm toward the conveyor is enhanced without mechanical manipulation.

Still another object of the invention is to provide apparatus of the above character with means whereby cooling air, which has been freed Another diiiiculty encountered in the opera- I tion of machines of the above character concerns the ultimate discharge of the dried material from the drying mechanism to conveyors which transport it away. In the past it has been found that the relatively thin film broke, buckled, and rolledy or folded over itself thereby delaying the free discharge of the film from the dehydratlng apparatus and causing accumulation thereoi before it reached the conveyor mechanism.

To the end that the above set forth difiicuities may be avoided, and as an important object of the invention there is provided herein an improved dehydrating apparatus wherein the dehydrated iilm is edectively cooled immediately upon its removal from the hot dehydrating drum: wherein the dim is easily. quickly, completely and emciently removed from the drum; and wherein the film is emciently aided in its progression from from condensed moisture, is impinged against the dried film, this impingement being accomplished by impinging air against one or both surfaces thereof.

It is a more specific object of the invention to provide dehydrating apparatus ofthe above character with a doctor blade assembly which has as-t sociated therewith a cooiair channel and down# wardly projecting jets whereby the removal vof thedried film from the surface of a drying drum by the doctor blade will be facilitated by the impingement of air against the material as it bends away from the surface of the drum. Under such conditions, it will be understood that the impinging cool air not only cools the adjacent surface of the film simultaneously with its removal from the drum, .but also tends to raise it away from the surface of the drum to aid the action of the doctor blade.

Another object of the invention is to provide an improved cooling air system which also serves to guide the film into a suitable disposal conveyor after it isl removed from the drum surface.

Still another specific object of the invention is to provide an improved apron construction for the` dehydrating apparatus .which has associated therewith a cool air duct whereby cool air is directed against the film to cool it and also to raise it away from the surface of the apron whereby the iilm falls more freely by gravity toward the conveyor without buckling or breaking and thus piling up.

Another important object of the invention is to provide means for oscillating or vibrating the apron or a part'thereof to further facilitate the progression of the iilm thereoverand to prevent the iilm from adhering thereto.

In accordance with other features of the inven tion, there is provided an improved arrangement of air ducts whereby drying air is impinged against both surfaces of the portion of the film which has been removed from the drier in order that it be guided toward a suitable conveyor and in order that a maximum drying effect may be obtained. As shown herein, one of the air ducts may be adjustably mounted formovement to the other side of the film so that the lifting force of the flow of air therefrom may be utilized to enhance the progress of the film toward the conveyor.

In accordance with another feature of the invention, an auxiliary apron is provided for deflecting the first run of film away from the disposal conveyor in the event that the drier is not hot enough to dry the film the desired amount.

Other objects and features of the invention will become apparent from the following specification and the attached drawings, in which:

Figure 1 is a side elevational View of the machine generally;

Figure 2 is a front elevational view thereof;

Figure 3 is an enlarged fragmentary view similar to Figure 2 with parts broken away;

'Figure 4 is a cross sectional view taken along the line IV-IV of Figure 3; and

Figure 5 is an enlarged fragmentary view similar to Figure 4.

Figure 6 is an enlarged fragmentary front elevational view of a modified form of apparatus embodying the invention.

Figure 7 is a cross sectional view taken on the line VII-VII of Figure 6.

Figure 8 is an end view ofthe upper air-duct taken from the right of Figure 6.

Figure 9 is a cross sectional view taken on the line IX-IX of Figure 6.

It is to be understood that the embodiments shown and described herein are for illustrative purposes and may be changed or modified without departing from the spirit and scope of the "invention as set forth in the accompanying claims.

As shown in Figures 1 and 2, the dehydrating apparatus includes generally a pair of spaced supporting members |0 and between which extend the various mechanisms for treating materials in.

a manner to be described presently.

The drying mechanisms include, primarily, drying drums l2 and I3 mounted for rotation with journals I4 and l5 respectively, these journals having the ends thereof suitably mounted for rotation in aligned bearings formed in the supporting members |10 and lAbove each of the drying drums I2 and I3 is a spreader roller I6 and I1 respectively. 'I'hese rollers are mounted on journals |8 and I9 respectively which also are mounted to rotate in aligned bearings formed in members l0 and I i. y

Adjacent each of the drums |2 and I3 is a conveyor trough and 2| respectively. each having therein a screw conveyor 22 and 23 respectively mounted on journals 24 and 25 and each having sprockets 24a and 25a respectively, fixedly, secured thereto.

Additionally, there is mounted on suitable bearings formed in the member |I a journal 28 upon which a drive pulley 21 and a drive sprocket 26a are fixedly secured, a journal 28 upon which a multiple sprocket drive 29 is mounted and a stud 30 upon which an idler sprocket 3| is mounted.

As shown in Figure 1, a drive chain 32 meshes with the drive sprocket 26a. the sprocket 29a of the multiple sprocket drive 29, sprocket ring |3a mounted upon the end of the drum I3, idler sprocket 3|, sprocket 25 of the screw conveyor 23, and again with the ring |3a of the drum I3.

Like the drum I3, the drum I2 is provided with a sprocket ring |2a, the latter meshing directly with the sprocket 29h of the drive 29.

Preferably the spreader rollers i6 and I1 are also provided with some driving means, and as shown herein they also are provided with sprocket rings |8a and |911 respectively which are adapted to mesh directly with the sprocket rings ila and |3a respectively. As shown in Figure l, the multiple sprocket drive 29 has a third sprocket 29c mounted thereon, and this sprocket has meshed with it a chain 31 which in turn meshes with the sprocket 24a whereby the conveyor screw 22 is rotated in the housing 20.

A drive belt 33 extends around the drive pulley 21 and around a `pulley 34 mounted on the shaft of a motor 35. The motor is suitably mounted as on a standard extending upwardly of the supporting member Il. As will be seen from Figure 2, the above described assembly may be housed in a suitable safety cover 3S.

From the foregoing, it will be seen that the drying drums |2 and I3, spreader rollers I6 and |1, and conveyors 22 and 23 will all be rotated by the motor 35 through the chain and sprocket assembly above described, the drums rotating in the direction of the arrows shown in Figure 1.

Any suitable drying medium such as hot air or steam may be passed into the interior of the drums -in any suitable manner, and the material to be treated may be suitably fed to the drum surfaces as at the nip formed by the drums and by the spreader rollers. After passing between the rollers, the material adheres to the drum surface as a thin film or sheet in which condition it may be readily dried.

To the end that the dried material such as distillery slop, dried milk, or sh refuse may be collected, agitated, and disposed of after the drying operation, there may be provided, at the disposal end of housings 20 and 2| arid the screw conveyors 22 and 23, elevators 43 and 44 respectively which feed the materals into a hopper 38 in which isarranged a suitable agitator 'driven by a motor 39 through belt 48, pulley 4|, and shaft 42.

As previously stated, the efficiency of the output of apparatus of the above character depends to a great extent upon the efficiency of the disposal of the treated material from the drum and the etliciency of the transmittal thereof from the drum to the conveyor. Furthermore, as stated above, the drying is attained by subjecting the material to high temperatures which if malntained for too long a period, cook the material, this cooking often affecting it detrimentally.

Referring to Figures 1, 2, and 3, the upper ends of supporting members I9 and terminate in bearings 45 and 46 in which doctor rods'41 are mounted for rotation. A similar film handling mechanism is provided for each drum, and for convenience like numerals will be applied to like parts on both sides of the machine. A doctor bar 48 is xedly mounted upon the doctor rod 41 and in accordance with the invention, a suitable compressed air duct is associated with the bar 4l. In the present embodiment, the bar 48 is liollowed out to provide an air passage as at 49, is recessed on its back surface to receive a removable doctor blade 50, and is provided with a longitudinally extending blade retaining plate Il which is held in position by bolts, one of which is shown at I2.

To the end that the pressure with which the edge of theblade SII bears against the surface of the respective dryer drum may be regulated, a suitable adjustment may be provided, and iorv that purpose, as is shown herein, there is pron vided an arm t3 and 5d mounted upon the bearings ill-l and it respectively. Each or the arms and'liii terminates at its upper end in an odset bearing to as shown associated with the arm Si@ in Figures l. and 3. A rotating, threaded spindle tt is extended through the respective bearings 5t and terminates in a hand wheel bl at its outer end. The spindle bt is rotatably anchored to an arm 58 at its inner end, the respective arm bd being mounted on a bushing t@ which is nxedly secured at each end of the doctor rod ill. Thus, it will be seen that rotation oi the hand wheels ill will cause rocking of the respective arm E@ and rotating movement of the respective rd di and thus movement of the edge ci the respective blade t@ toward or away irons. the surface of the respective drum.

To the end that the specific objects of the invention may be attained, there is provided herein, as above set forth, an improved doctor bar llt and also an improved apron shown generally at tt.

Referring particularly to Figures @l and 5, the cool air duct du 'of the doctor bar to is provided with. a plurality of air outlet passages lll which extend entirely across the bar for purposes to be described presently. lin order to obtain proper distribution'of the air from the channel or duct liti, each of the passages lll is provided with a valve screw t2. The passages @l are positioned in the doctor bar llt at such an angle that the onrushing air from the channel Il@ is directed downwardly against the loading tace of the doctor blade 't and toward the cutting edge thereof.

As shown inK Figures tand 5, the nlm of dried material is being carried upwardly on the surface of the drum it when it engages the doctor blade t@ to be separated from said surface. As previously stated, the nlm titl adheres to the surface of the drum during the drying operation and is often tacky, thereby rendering it diiiicult to remove from the surface oi the drum by means of the knife alone.I It will be understood that any resistance to this removal will, of course, result in a rolling or buckling of the film and thus the clogging of the machinery in the vicin- "ity of the point where the doctor blade engages the surface of the drum.

To the end that the resistance of theilm to easy removal from the surface of the drum by the doctor blade may be overcome, the valves t2 may be so regulated that the compression of air in the air channel 49 will provide a rush of the' air through the ducts 6I and downwardly into the nip wniei is formed between the surface of the drum and the curled film which has already been removed from that surface.

Thus, it will be seen that the impingement of the air is effective to impart a lifting tendency to the film as it reaches, theblade 50, whereupon the blade completes the removal from the surface.

It will also be understood that this impingement of cool air against what was previously the under surface of the film will effectively cool that surface simultaneously with its removal from the hot surface of the drum to prevent continued cooking of the residue due to the inherent heat which has been created by the heat from the drum. l

The apron shown generally at $0 is provided primarily for the purpose of receiving the film in the present instance, the apron includes u tip portion ,tt which has-a tapered, yetsubstantially rounded iollowing edgeior receiving the lilm tu in sliding relationship after it has ,been removed from the surface of the drum and bent back upon itself. The portion tt maydbe sultably formed from sheet metal and lilre the drum extends from the supporting element ill to the supporting element il.

To the end that the removal ci the film troni the drum it may be facilitated by being pre-1 liminarily loosened, the tip portion tt oi' the apron is mounted upon a rod tt extending therethrough, the ends of this rod beingfsupported by depending supporting elements t8 w ch are, in turn, supported attheir" upper en s by the doctor rod dll. lateralylbratory movement is imparted to the tip' Gt by means of a; lever 61 which is secured plvotally to one end ci the bar- 't5, the lever till comprising one arm *of a bell crank, Athe lever tt comprisin'gthe other erm thereof. A pitman tt -is pivotally secured to thev outer end of the lever tu and has its remote end suitably rotatably connected with arl-'ccentricv shown generally at 1d (see-Fig.' 2), the latter being mounted at-the 'end oi the `conveyor' shaft it to rotate therewith.

From the foregoing, it will be seen that when the motor is turned on, the'shait 2t will be rotated as previously described-'and the tip portion lili of the apron will loe'vibratedlaterally by virtue of the eccentric it'and the bell cranlr. levers til and The apron further comprises a depending portion li which is preferably hollow and has compressed, cooling air supplied thereto from any suitable source such as through connections it, "i3, and 'lll (see Fig. 2l, a branch pipe lll being adapted to supply the compressed air into the channel il@ of the doctor bar lil. x

As shown clearly in Figures i and 5, the hollow portion il ol the apron terminzites at its upper edge in a compressed air discharge pas sage ,lo which directs the air into the hollow tip portion 64. This passage may extend longitudinally of the hollow portion 1| of the apron direction of the path of travel of the film. With` such a, construction it will be seen that due to the compression within the apron portion 1I the air therein will be discharged upwardly4 into the-tip portion 6l and then downwardly over the outer side of the corrugated formation while at the same time the air will be .discharged through the ports 1l to impinge against the adjacent surface of the downwardly moving film of dried material with a glancing action in a downward direction, this particular direction of the air being caused first by the somewhat downward projection of the passages or ports 18 and further by the downward movement of the compressed air from beheath the tip portion 84 as indicated by the arrows in Figure 5.

The total effect of the last described impingement of air against the leader surface of the film is to cool this surface immediately after separation of the lm from the drum, to tend to blow the film loose from the engaged outer wall o f the apron, and to impinge against the film in the direction in which it is moving thereby aiding in its progression downwardly. toward the conveyor.

From theforegoing, it will also be seen that' the film 63 is being effectively dried by the heat of the drum up to the time that it reaches the blade 50, whereupon it is removed from the surface by the blade 58 and by the airdischarged through passages 6| and simultaneously the surface of the film which lays adjacent the heated surface of the drum during the dehydrating operation is immediately cooled. Thereafter the other surface of the film is impinged upon by the cooling air which is discharged from the passages 16 and from the passages 1 8, whereby the cooling operation is carried further, this latter impingement also serving to progress the film over the apron in a manner to prevent buckling and rolling thereof to delay thedischarge of the dried and cooled film 63 to 'the conveyor.

Another highly important feature of the invention may be attributed tol the impingement of air against the under surface of the film as it is discharged from passages 16 and 18. It is to be vnoted that the progression of the film over the apron downwardly toward the conveyor is accomplished without the aid of any mechanical handling devices such as rollers or thev like. Instead, the facilitated progression downwardly of the film is accomplished solely by the impingement of air thereagainst. Thus, mechanical handling and manipulation of the firm and the resulting possibility of clogging or breakage thereof is entirely avoided,

As previously stated the cooling air, under certain conditions, contains moisture in sumcient amount so that condensation occurs within the ducts with the result that the moisture is impinged upon the film as it is removed from the drum, to the end vthatl the dehydrating function of the drum is, in a measure, defeated.

In order that the detrimental effects of this condensed moistu''e may be obviated, the construction shown in Figures 6 and 7 may be utilized.

' In this construction the air duct 18 associated with the doctor bar 48a has a series of tubes 88 extending through the wall thereof throughout its length. The tubes 88 direct the flow of a stream of air from the duct 19 to the film 8| at the point of the drum IZa which is engaged by the doctor blade 58a. As will be seen from Figures 7 and 8, the tubes 80 have their upper endsl extending above the inner surface of the duct 18 and, consequently, condensed moisture as it accumulates in the ducts will be. entrapped therein and prevented from the discharge through the tubes 88 agains't the film along with the dehydrating air. 'Ifo the end that the duct 18 may be cleared of condensed moisture from time to time. a valve 8l mounted on a spindle 82 and having a. handle 88 is mounted in one end of the duct 18 and may be opened periodically to afford discharge of the condensed liquid.

As previously stated, the film, when removed from the drum, is somewhat tacky, and thus its' progress from the drum to the conveyor is greatly facilitated by impinging air against the inner surface thereof as it falls, to aid its progress downwardly through the conveyor. Under these circumstances, the air blast is calibrated to maintain the falling lm in a particular posit-ion so that it is discharged directly into the conveyor trough. If, however, the density or thickness of f' the film decreases after the air blast is calibrated,

it will be seen that the film will be blown out of alignment with the conveyor trough by the air blast and to the end that it may be realigned without recalibration of the air flow, there is provided an auxiliary duct 84 as shown in Figures 6 and 7.

In this construction air from ducts 18 and 84 is directed against one surface of 'the film 8| while air from a duct 85 is directed against the rear surface thereof. The ducts 19, 84, and 85 are each connected with a main duct 88 which communicates with a suitable source of air supply and has a flexible section 81 interposed between the duct 85, having apertures 85a therein, and the duct 84 having apertures 84a therein.

While the duct 84 is normally used in the manner shown in Figure 7, that is, with the air blast therefrom being directed against the outerI surface of the film as it falls into the conveyor trough 28a, it may bevdesir'able, in the event that the film is particularly heavy, that the duct 84 be so positioned that the ai-r blast therefrom be directed against the nether surface of the film as is the case with the duct 85. To the end that this adjustment may be made, the duct 84 is embraced by a U-bolt 84b at each end thereof, the U-bolt being slidably mounted by nuts 84e inslots 88 formed in brackets 89 mounted across the conveyor trough 20a and secured in position by means of bolts 80, which extend through longitudinal flanges 8| of the conveyor trough.

From the foregoing it will be seen that by loosening the nuts 84e, the duct 84 may be shifted laterally of the members 88, the section 81 flexing to permitv this movement.

The duct 84 is connected with the flexible section 81 through an elbow 82 which is constructed at its adjacent end to receive the end of the duct 84 in leak-proof, rotatable relationship whereby the duct may be rotated for predetermining the direction of the air flow therefrom by movement of the handles 83.

Under certain circumstances, when the apparatus disclosed herein ed up, it is found that upon the film is not as great as that ultimately required. If, therefore. this first run of the film is directed into the conveyor trough, it subsequently becomes mixed with the subsequently particularly is first startthe dehydrating effect lremoved film which is properly dried and increases the moisture content thereof to an undesirable point. To the end that this first run of the film may be deflected from the conveyor trough there is provided herein, as shown in F13- ures 6, 7, and 9, an auxiliary apron 84 which, when in the position shown in Figure 7, acts as a, guard but which may be pivoted about its lower end so that it rests against the apron 1|a. When in this latter position, it will be seen that the film discharged from the drum 12a will be de.

iiected from the conveyor trough and may be collected so long as its moisture contentV is greater than that which is ultimately desired. The auxiiiary apron t4 may be mounted upon the conveyor trough in any suitable manner and from Figures 7 and 9 it will be seen that, in the present instance, eyelets are secured to the outer iiange iii or the trough and are adapted to reccive lugs it which are stamped out from or secured to the outer face of the apron gli.

i claim as my invention:

l. The combination with a dehydrating machine having a rotatable, heated dehydrating drum, means for applying a hlm oi material to be treated to the suriace of said drum'and a doc tor blade having a scraper edge for removing said film from the drum after the dehydrating operation, oi means for directing a stream oi' fluid toward the scraper edge between the blade and that surface oi the nlm which traveled in juntaposition tothe surface oi the drum during the dehydrating operation to act at the `point ot separation oi iilrn from the drum surface byV the scraper edge i'or maintaining said edge in clean condition, and means ior directing a stream of fluid against the other surface of the film inthe vicinity of the point of engagement between the doctor blade and the drum surface.

2. The combination with a dehydrating machine having a rotatable, heated dehydrating drum, means for applying a 111m of material to be treated to the surface of said drum, a doctor blade for removing said nlm from the drum suriace and a doctor bar tor maintaining said blade in operative position, of a compressed air duct associated with said doctor bar having air discharge passages positionedfon the side of the blade opposite the side .thereof adjacent the drum and directed toward the operative edge ofthe blade and toward the junction of the surface of the drum with the juxtaposed surface of the film as it is being separated from the drum surface by said blade, an apron for slidably receiving said hlm as it is turned back upon itself, a compressed air duct associated with said apron having air discharge passages directed in the direction oi the. path of travel of said film to impinge air against the film.

3.The combination with a dehydrating machine having a rotatable, heated dehydrating drum, means for applying a film of material to be treated to the surface of said' drum and a doctor blade having an operating edge for removing said film from the drum after the dehydrating operation, of means for directing a stream of cooling air toward said edge between the blade and lm to impinge on that surface of the mm which traveled in juxtaposition to the surface of the drum during the dehydrating operation for pushing the film away from said edge and means for impinging a stream of cooling air on the other surface of the film, said streams being impinged on the surfaces before the material beingtreated is overheated by the residual heat imparted thereto by theheated drum.

4. The combination with a' dehydrating ma.- chine having la rotatable, heated dehydrating drum, means for applying a film of-material to be treated to the surfaceof said drum,v and a doctor blade for removing said film from the drum after the dehydratingv operation, of a compressed air duct associated withsaid doctor blade having air discharge passages directed toward the operative edge of the blade on the side of the blade opposite the side thereof adjacent the y the drum, and means for drum whereby air discharged from said passages will maintain the blade edge in a clean condition while assisting the blade in turning the :dim baclr on itself,.an apron for slidably receiving said hlm as it is turned back upon itself, and a cornpressed air duct associated with said apron having air discharge passages directed toward the hlm in the direction of travel thereof over said apron.

5. The combination with a `de'hydrating inachine having a rotatable, heated dehydrating drum, means ior applying a nlm oi material to be treated to the surface of the A luf and a doctor blade for removing said i'llm from the drum after the dehydrating operation, of a doctor bar, said bar having means for mounting the doctor blade thereon, a compressed air duct extending longitudinally thereof with air discharge passages along its length directed toward the operative edge of the blade, an apron assembly adapted to receive said :dim in slidable engagement as it progresses thereover, said assembly including a stationary hollow portion and a hollow tip portion with a nose positioned in advance of the operative edge oi the doctor blade over which the lm may be folded upon itself as it is separated from the drum surface by the blade, means ior oscillating said tip portion relative tosaid stationary portion and means for flowing cooling air through the stationary portion into the tip portion for ejection therefrom between the hlm and stationary portion.

6. A dehydrating machine comprising a roe tatable horizontal dehydrating drum arranged' iol' receiving liquid or semi-liquid material thereon to form a dried film or sheet therefrom, means for rotating said drum, a scraper having a leading edge cooperating with said drum for removing the film or sheet from th drum, an apron arranged for holding the rerljed iilm away from cting a stream of fluid toward the leadingr edge of the scraper on the side of the scraper opposite the side thereof adjacent the drum to act on that surface of the lm which traveled in juxtaposition to the drum at the point of separation of the film from the drum surface for assisting the scraper and maintaining the leading edge thereof in a clean condition, said scraper shielding said stream from the drum to minimize contacting of the `fluid with the drum.

7. In a drum drier machine, a doctor bar swingably mounted on the machine for movement toward and away from the drum thereof, a doctor blade detachably carried by said bar for scraping the drum surface, a compressed air duct associated with said bar having discharge orifices along the length thereof for impinging compressed air on the operative edge of the blade at the side ofthe blade which is opposite the side thereof adjacent the drum, and individually adjustable means cooperating with each orifice for regulating the capacity thereof.

8. In a. drum drier machine having a drum rotatably mounted between side frames, a. hol- 9. In a drum drying machine, an apron assembly comprising a stationary apron part having a surface adapted to receive thereover the dried material from said drum, a tip disposed over the receiving end of said apron, and means for oscillating said tip relative to said apron and said drum for preventing adherence of the dried material.

10. The combination with a dehydrating machine having a rotatable, heated dehydrating drum, means for applying a film of material to be treated to the surface of said drum, and a doctor blade for removing said lm from the drum after the dehydrating operation, of a receiving trough for said fllm and an apron having a lower end swingably mounted on the side of the trough remote from the drum and an upper edge positioned in the vicinity of said drum to receive the film on the exposed surface thereof to deect the same from said trough, and said apron being swingable from said position to move its upper edge away from the drum and out of the path of film to the trough.

11; The combination with a dehydrating machine having a rotatable, heated dehydrating drum, means for applyin-g a fllm of material to be treated to the surface of said drum, and a doctor blade assembly for removing said film from the drum after the dehydrating operation, of a film receiving trough and an apron member having the lower edge thereof pivotally mounted on the side of said trough remote from the dehydrating drum and being arranged to be pivoted across the top of the trough with the upper end thereof disposed adjacent the drum to receive the film as it is removed from the face thereof to deflect thefilm against passage into the trough.

12. The combination with a dehydrating machine having a rotatable, heated dehydrating drum, means for applying a film of material to be treated to the surface of said drum, a doctor blade for removing said film from the drum surface, and a doctor bar for maintaining said blade in operative position. of a compressed air duct associated with said doctor bar having air passages directed toward the operative edge of the blade and toward the junction of the surface of the drum with the juxtaposed surface of the hn as it isbeing separated from the drum surface by said blade, said passages including tubular members having their inner ends disposed within said duct and extending upwardly beyond the inner surface thereof to entrap condensed liquids formed in said duct and having their outer ends between the outer face of the blade and the film.

13. In a dehydrating machine having a rotatable dehydrating drum, means for applying a film of material to the surface of the drum, means for removing said film from the surface of the drum and for turning the removed portionback upon the portion still auihering to the drum and a receptacle for receiving said film as it gravitates from the surface of the drum after removal therefrom; a compressed air duct having air passages disposed longitudinally thereof and means for vmounting said compressed air duct for movement toward and away from the adjacent portion of the surface of the drum across the top of said receptacle and for rotation about its longitudinal axis to vary the direction of said air passages.

i4. 'I'he method of cooling a film dried on a heated drum as it is scraped from the drum which comprises directing cool air between the film and the scraper toward the active edge of the scraper to act on the film at said active edge, and shielding the drum from said air with the scraper.

15. A dehydrating machine including a rotatable horizontal dehydrating drum arranged for receiving liquid or semi-liquid material thereon to form a dried film or sheet therefrom, means for rotating said drum, a scraper on the ascend,

ing side of the drum having a leading edge projecting between a film on the drum and the drum, said leading edge being effective for scraping the ascending film from the drum while allowing the scraped off film to descend, an apron arranged for holding the descending portion of the film away from the ascending portion thereof, and a duct associated with said scraper having orifices along the length thereof arranged for directing jets of fluid toward the leading edge of the scraper on the side of the scraper opposite,

that side adjacent the drum to fiow toward the leading edge of the blade and act on that surface of the film which traveled in juxtaposition to the drum at the point of separation of the film from the drum, said scraper shielding said fiuid jets from the drum.

16. The method of simultaneously cooling and removing film from a heated drum which comprises scraping the film from the drum, directing cool air under pressure toward the operative edge of the scraper and toward the junction of the surface of the drum with the juxtaposed surface of the film to maintain the scraper in a clean condition and to cool the film, and shielding the drum from said cooled air with said scraper.

17. The method of removing residual heat in a dried film While removing the film from a traveling heated surface Without cooling the surface which comprises scraping an ascending flhn

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