US2930140A - Material drier and method - Google Patents

Description

March 29, 1960 L. K. IRISH MATERIAL DRIER AND METHOD 2 Sheets-Sheet 1 Filed July 29, 1957 INVENTOR. LAURENCE K. IRISH BUCKHORN, CHEATHAM a BLORE A 7' TORNE VT March29, 1960 K. IRISH MATERIAL DRIER AND METHOD 2 Sheets-Sheet 2 Filed July 29, 1957 IN V EN TOR.

BUCKHORN,

40 CHEATHAM 2\BLORE ATTORNEYS MATERIAL DRIER AND METHOD Laurence K. Irish, Silverton, Greg, assignor to Lloyd B. Larsen, Silverton, Oreg.

Application July 29, 1957, Serial No. 674,648

I 12 Claims. '(Cl. 34-437) This invention relates to a material drier and method and more particularly to an apparatus and method for rapidly and efficiently drying loose bulk materials.

with a heated drying gas while being agitated and advanced through a drier. The wet material, while being initially heated, is brought into contact with a small portion of the drying gas in countercurrent relationship therewith, and the resulting portion of cooled and saturated spent drying gas is immediately discharged from the drying operation. The partly dried material is then subjected to continued agitation in contact with additiona1 heated drying gas, the final treatment being a countercurrent relationship with a fresh supply of dry heated gas.

The apparatus of the present invention includes a rotatable cylinder or drum with its axis inclined to the horizontal. The cylinder contains a conveyormeans having a first flight positioned in an enclosure providing a passage for the gas employed in the initial treatment referred to above, the final treatment being a tumbling operation in the cylinder in contact with drying gas passed through the cylinder, a second flight of the conveyor being employed to provide an intermediate drying treat- .ment. The apparatus also includes means for generating the hot drying gas and delivering it into the drying cylin- -der and means for exhausting the spent gas, as well as means for delivering material to be dried into the cylinder and discharging it therefrom. The invention results in more effective use of the drying gas employed and more elfective use of the space in the rotating drying cylinder thus providing eflicient drying with minimum space requirements and consequent savings in installation costs as well as in operating expenses, including the cost of heating the drying gas. Also the drying operation is quickly accomplishei and can be carried out at moderate temperatures so as to avoid damaging the material being dried. Y

material.

Another object of the invention is to provide a material drier and method in which loose bulk material such as grains, sawdust, chopped forage and the like is subjected, in a continuous operation, to an initial treatment with a small portion of the drying gas andv the resulting ..cooled. and saturated gas immediately discharged from the. operation, the material being, subjected to a further A further object of the invention is to provide drying apparatus for loose bulk material in which conveyor means and separate passages for drying gas are employed within arotating cylinder type of drier to provide more eflicientcontact-With the drying gas passed through sirc-h cylinder.

Other objects and advantages of the invention will appear in the following description thereof given in corn nection with the attached drawing of which:

Fig. 1 is a perspective viewof the drier of the present invention with parts broken away to show the interior construction;

Fig. 2 is a vertical section taken on the line Fig. 1;

Fig. 3 is a view similar to Fig. 2 illustrating amodification of the drier; and 1 g Fig. 4 is another view similar to Fig. 2 showing annther modification of the drier.

Referring more particularly to the drawing, Fig. 511 shows a drier having a rotating cylinder 10 and stationary end closures 12 and 14 at its inlet and discharge ends, respectively. The major portion of a conveyor means 16 having upper and lower flights 18 and 20 respectively is positioned within and extends axially of the cylinder 10, the flights 18 and 20. passing through apertures in the stationary end closure'12. The apparatus also includes a supply hopper 22 positioned above the exterior portion 0f the upper flight 18 of the conveyor means and a discharge chute 23 for dried material and additionally includes a means 24 for generating and introducing-heated,

drying gas into the cylinder through the end closure '14 and a flue 26 for connection to an exhaust blower '(not shown), the flue 26 being secured to the stationary end closure 12.

The cylinder 10 may be of a suitable metal and has its tively, the wall of the cylinder between the flanges 28 and 30 having the greater part of its area covered with suit-- 7 able heat insulating material 32, it being understood that the end closures 12 and 14 as well as the heated gas generating means 24 may also be covered'with heat insulating material, if desired. The cylinder 10 is provided intermediate its ends with a plurality of circular tracks 34 engaging rollers or trunnions 36, journaled' in brackets carried by side rails 38 forming part of; the frame ofthe machine, the side rails 38 being secured together by suitable crossrails 40. One or more of the trunnions 36 may be rotated to rotate the cylinder, the drive being through a shaft 42 and a speed reducer 44 from an electricmotor 46. The speed reducer 44 and motor 46 may be' s'up- V ported upon an end cross member 47 also forming part ofthe frame of the machine.

The conveying means 16-includes longitudinally extend- .ing side members 48 and 50 for the upper and lower flights 18 and 20, respectively, the side members 48 and r 50' for each side of the conveyor 16 being connected together at the inlet end of the drier by upstanding frame members 52' secured to-the end crossmember 47 and also supporting the feed-hopper 22. At the discharge end of. the cylinder, the side members 48 and 50 are connected together by uprights 54 secured to the end closure .14

which in turn is supported by the standards 56 mounted on the side rails 38. The side members 48 of theupper flight 18 of the conveyor are connected at their bottom edges by a longitudinally extending, plate 58 to form a conveyor trough. The plate 58 extends under the feed hopper'22 but terminates-short of the end of the conveyor adjacent the end closure 14 to provide an opening through which material may drop from the upper flight 18 of the conveyor to the lower flight 20. Theside-members 50 of the lower flight 20 of the conveyor are :also connected together at their lower edges by a plate 60 to 2,930,140 1 V Patented Mar. .29, i

form a trough. The plate 60 terminates short of the stationary end closure 12 at the inlet end of the cylinder to provide an opening through which the material being dried drops into the lower portion of the cylinder.

The conveyor means 16 also includes a pair of laterally spaced endless chains 62 running on sprockets 64, the chains 62 having pusher plates 66 spaced therealong and extending between the chains. The chains 62 and pusher plates 66 of the conveyor are positioned in the troughs formed by the side members 48 and 50 and the bottom plates 58 and 60 and the sprockets 64 which are positioned upon the shaft 68 are driven from the speed reducer 44 through a chain 70 to drive the chains 62. The lower portion of the feed hopper 22 is positioned just above the upper flight 18 of the conveyor and the chains 62 are driven in a direction such that pusher plates 66 carry material to be dried into the cylinder 10 on the plate 58 through an aperture in the end closure 12. The chains and pusher plates travel out of the cylinder through another aperture in the end closure 12. The end closure 12 may be supported by the crossrail 40 of the machine frame as well as the side members 48 and 50 of the conveyor frame and may be made of several pieces, as indicated in Fig. 2, secured together by any suitable means (not shown) in order to facilitate assembly of the apparatus. The loose bulk material fed into the hopper 22 is moved as an agitated advancing stream along the bottom plate 58 of the upper flight of the conveyor into the cylinder 10 and is dropped over the end of the plate 58 onto the plate 60 of the lower flight of the conveyor. The material being dried is then carried back toward the inlet end of the cylinder and dropped over the end of the plate 60 into the bottom portion of the cylinder.

As shown most clearly in Fig. 2, the interior of the cylindrical wall of the cylinder 10 has secured thereto a plurality of circumferentially spaced, longitudinally extending scoop elements 72. The scoop elements have their inner ends curved in the direction of rotation so that they carry material being dried from the lower portion of the cylinder 10 upwardly to a position approaching the top of the cylinder. Such material is thereby repeatedly elevated and dropped through the drying gases in the cylinder 10.

The upper flight 18 of the conveyor is provided with a baflle means including peaked roof structure 74 to prevent any material carried upwardly by the scoop elements 72 from being dropped into the upper conveyor flight and also to provide, in conjunction with the bottom plate 58 of the upper flight of the conveyor, an enclosed passage or flue for drying gas as later described in more detail. The bathe means also includes side walls 76 and 78 extending between the side members 48 and 50 of the upper and lower conveyor flights to prevent material carried upwardly by the scoop 72 from being dropped into the lower flight of the conveyor. At least one of the side walls, for example, the wall 76 may be of screen or other foraminous material allowing passage of drying gas therethrough but preventing passage of particles of the material being dried.

As indicated in Fig. 1, the longitudinal axis of the cylinder 10 is inclined to the horizontal such that the dis- 'charge end of the cylinder is lower than the inlet end, the

stationary closure 14 for the discharge end of the cylinder being provided with a material outlet opening 80 adjacent the discharge chute 23. It is apparent that material discharged over the end of the bottom plate 60 of the lower conveyor flight adjacent the inlet end of the cylinder 10 will be repeatedly elevated and dropped through the drying gas and that it will gradually advance toward the discharge and of the cylinder so as to be discharged through the opening 80. The rate of such advance can be controlled by adjusting the inclination of the axis of the cylinder 10, for example, by jacks 84, one of which is shown in Fig. 1.

The means for generating heated drying gas may include a cylindrical casing 86 having one end secured to the outer surface of the end closure 14 for the cylinder 10 so as to extend concentrically therefrom. The casing 86 has an end closure 88 at its other end and a burner 90 is employed to introduce heated products of combustion into such other end. The burner 90 is shown as being of the oil burning gun type having its barrel extending coaxially of the casing 86, but any suitable source of heated products of combustion such as a burner for fuel gas or even solid fuel may be substituted for the oil burner 90. The interior of the casing 86 is provided with inner and outer bafile members 92 and 94 respectively. Both bathe members are of cylindrical form, and both are positioned concentrically of the casing 86 with the inner baflle member 92 having one end attached to the closure 83 for the casing 86. The outer baffle member 94 is positioned so as to be axially spaced from both the closure member 88 for the casing 86 and the end closure 14 for the cylinder 10, and has an end wall 96 adjacent but spaced from the end closure 14. The bafiie member 94 may be supported in spaced relationship with the end closures 14 and 88 and the baflle member 92 and casing 86 by any suitable spider members (not shown). The end closure 14 for the cylinder 10 has a centrally disposed gas inlet opening 100 and it will be apparent that heated products of combustion from the burner 90 will follow a tortuous path through the casing 86, such products of combustion advancing to the right through the interior of the baflle 92, then to the left between the bafiles 92 and 94 and again to the right between the baflle 94 and the peripheral wall of the casing 86, and thence into the cylinder 10 through the opening 100. The end closure 88 for the casing 86 is provided with a plurality of air inlet openings 102 having suitable adjustable closure means or dampers 104, the openings 102 establishing communication between the atmosphere and the space between the battle 92 and the peripheral wall of the casing 86. Since the flue 26 at the opposite end of the drier is connected to an exhaust blower, a slight vacuum will be produced within the casing 86 so that controlled amounts of air are drawn in through the openings 102 to admix with and temper the heated products of combustion to thereby provide a drying gas having a desired temperature. The amount of air can be controlled by the dampers 104 to provide any desired temperature of the drying gas.

The operation of the drier thus far described is believed to be apparent. The loose bulk material which may be any type of material made up of granules, grains or other particles containing moisture or other liquid is introduced into the feed hopper 22, The conveyor 16 is driven at a desired rate of speed from the motor 46 through the speed reducer 44 and chain 70 so as to carry a stream of the material to be dried into the cylinder 10 and through the enclosed elongated passage around the upper flight 18 of the conveyor. The material to be dried is thereby carried over the plate 58 which is heated by product of combustion within the cylinder 10 and is agitated while in contact with heated drying gas passing countercurrent to the advancing material through the elongated passage just described. The partially dried material is discharged over the end of the plate 58 onto the plate 60 of the lower flight 20 of the conveyor and the material then is further agitated while being carried back toward the inlet end of the cylinder 16 by the conveyor and while in contact with heated drying gas and with the plate 60 which is also heated by the drying gas. The further dried material is then discharged over the end of the plate 60 into the lower portion of the cylinder 10. The cylinder 10 is rotated at any desired speed and the material being dried is repeatedly elevated and dropped through the drying gas therein. Since the discharge end of the cylinder 10 is lower than the inlet end, such material progresses toward the outlet end of maniac the cylinder so as to be discharged from the-opening 80 and the trough 82.

Products of combustion produced by the burner 90 .are introduced into the casing 86 and are admixed therein with air admitted through the openings 102 in controlled amounts so that heated drying gas having a desired temperature is introduced into the outlet end of the cylinder 10 through the opening 10%. Such temperature will usually be maintained just below that which will char or otherwise deleteriously affect the material being dried. A portion of such drying gas passes through the elongated passage for the upper flight 18 of the conveyor to the flue 26. Such gas progresses counter-current to the incoming material on the upper flight of the conveyor while such material is being raised to a drying temperature and is rapidly cooled and saturated with vapors so that it has no further effectiveness as adrying gas. In the arrangement shown, such gas is immediately discharged from the drying operation so as to not interfere with further drying of the material in the cylinder. The

7 material discharged over the end of the plate 53 comes into contact with fresh drying gas and additional moisture is removed therefrom during agitation and transport on the heated plate 60 of the. lower flight of the.

conveyor. The material is then finally subjected to a counter-current drying operation in contact with fresh drying gas while being repeatedly elevated and dropped through such gas. The stream of drying gas passing through the cylinder from the outlet end thereof to the inlet end for material to be dried is of substantial length and height, the gas adjacent such outlet end being hotter than that adjacent the inlet end and the gas in the upper part of the cylinder being hotterthan that in the lower part. The incoming material is carried as a thin layer through the upper part of the cylinder to the hot end thereof and is thereby subjected to a rapid heating operation with rapid initial removal of moisture after which it is carried as a thin layer back toward the cooler end of the cylinder so as to reduce to a considerable extent the temperature gradient along the cylinder, the material then being gradually moved again toward the hot ,end of the cylinder while being repeatedly tumbled in the drying gas. The apparatus thus provides for more eflicient use of the drying gas. The space in the drying cylinder is also more advantageously employed and there is no possibility of any of the material being short circuited through the drying operation.

A modification of the apparatus is shown in Fig. 3. in this modification both walls 106 extending between the upper and lower flights of the conveyor are of screen or other foraminous material but otherwise the apparatus is the same as that shown in Figures 1 and 2. A further modification is shown in Fig. 4'in which the lower flight 20 of the conveyor is housed in a separate'structurefrom that of the upper flight 18. The upper flight of the conveyor is provided with peaked roof structure 74 shown in Figures 1 and 2 which cooperates with the bottom a plate 58 to provide an enclosed elongated passage surrounding such upper flight. Inthe modification of Fig. 4, however, no sidewalls extend between the upper and lower flights of the conveyor, but instead the lower flight of the conveyor is also provided with a peaked roof structure 108 cooperating with the lower plate 60 to form a separate elongated passageway for drying gas around the lower flight of the conveyor. The operation of the modification shown in Fig. 3 and Fig. 4 is substantially the same as that of the apparatus shown in Figs.

elongated passages around conveyor. flights.

I claim: I

1. In adrier for loose bulk materials including -grain, sawdust, chopped forage and the like, and comprisinga rotary cylinder having an inlet end and an outlet end and means for tumbling the materials through the'interior thereof, said cylinder having imperforate cylindrical walls retaining said materials in said cylinder and being inclined so that the material travels from the inlet end of the cylinder toward the outlet end while being tumbled and is ejected therefrom at the outlet end, means for introducing the material'into the cylinder including conveying means stationary with respect to the rotary motion of the cylinder and extending longitudinally through the interior of the cylinder from end to end thereof including a first conveyor flight for conveying the'material from 1 r the inlet end to the outletjend, a second conveyor flight receiving the material from said first flight at the outlet 7 end for conveying the material from the outletend back toward the inlet end, said second flight discharging said material to the interior surface of the cylinder'at the inlet 'end, and bafile means within said cylinder for preventing the conthereof, and means for passing a heated drying gas through said cylinder in a direction from the outlet end to the inlet end, said cylinder having imperforate cylindrical walls retaining said materials in said cylinder and being inclined so that the material travels from the inlet end of the cylinder toward the outlet end while being tumbled and is discharged therefrom at the outlet end,

means for introducing the material into the cylinder comprising conveying means stationary with respect to the rotary motion of the cylinder and extending longitudinally from the exterior of the inlet end of the cylinder through the interior of the cylinder from end to end thereof including an upper flight for conveying the material from the inlet end to the outlet end, a lower flight receiving 1 the material from said upper flight at theoutlet end for conveying the material from the outlet end back toward the inlet end, said lower flight discharging said material to the interior of the cylinder at the inlet end, and baflle means within said cylinder for preventing the materials being tumbled fromdropping onto the conveying means.

3. A drier for loose bulk materials including grain,

'sawdust, chopped forage and the like, and comprising a rotary cylinder having means for tumbling the material from top to bottom of the cylinder, the cylinder having imperforate cylindrical walls retaining said materials in said cylinder and being inclined from one end toward 1 and 2, except that in Fig. 3 there is more opportunity for interchange between the gas in contact with the material in the lower flight of the conveyor and that in contact with the materials being further dried as they are repeatedly elevated and advanced along the" cylinder 10, while in Fig. 4, three substantial independent streams of drying gas are provided by reason of the enclosed the other to provide an upper end and lower end of said cylinder so as to move the material progressively thereal ong, conveying means stationary with respect; to the rotary motion of the cylinder and arranged within the "cylinder for conveying a layer of the material longitudinally of the cylinder from the upper end ofjthe cylinder through the upper portion thereof to the lower end of the cylinder, then back to the upper end of the cylinder through the lower portion of the cylinder, said'conveyor means discharging the material thus conveyed through the lower portion 'of the cylinder onto the inner surface 7 of the cylinder adjacent the'upper end of the cylinder, means to generatea hot gas and introduce the sameinto the lower end of the cylinder, means to exhaust said gases from the upper end of the cylinder, and a stationary flue within the cylinder and surrounding the moving layer of material travelling upon 'said conveying means through the upper part of the cylinder toward the lower end, said flue being open at both ends whereby hot gas both .the upper meow is conducted in countercurrent flow across the material when first introduced through the cylinder and becomes saturated with moisture and the saturated cooled gas is discharged from the cylinder, the remainder of the passage of the materials thereafter being through relatively dry gas.

4. A drier for loose bulk materials including grain, sawdust, chopped forage and the like, and comprising a rotary cylinder having imperforate cylindrical walls retaining said materials in said cylinder and having means for tumbling the material from top to bottom thereof, the cylinder having imperforate cylindrical walls retaining said materials in said cylinder and being inclined from one end toward the other to provide an upper end and lower end of said cylinder so as to move the material progressively therealong, conveying means stationary with respect to the rotary motion of the cylinder and arranged within the cylinder for conveying a layer of the material longitudinally thereof from the upper end of the cylinder through the upper portion thereof to the lower end of the cylinder, then back to the upper end of the cylinder through the lower portion of the cylinder, said conveyor means discharging the material thus conveyed through the lower portion of the cylinder onto the inner surface of the cylinder adjacent the upper end of the cylinder, means to generate a hot gas and introduce the same into the lower end of the cylinder, means to exhaust said gases from the upper end of the cylinder, and a stationary flue within the cylinder and surrounding the moving layer of material travelling upon said conveyor, through the upper part of the cylinder toward the lower end, said flue being open at both ends whereby hot gas is conducted in counter-current flow across the material when first introduced through the cylinder and becomes saturated with moisture and the saturated cooled gas is ejected from the cylinder, the remainder of the passage of the materials thereafter being-through relatively dry gas, and baflle means for preventing the material being tumbled in said cylinder from admixing with the material being conveyed from the lower end to the upper end of the cylinder.

5. A drier for loose bulk materials including grass, sawdust, chopped forage and the like, and comprising a horizontally extending cylinder having imperforate walls retaining said materials in said cylinder, a first end closure for one end of said cylinder and having a gas inlet opening therethrough, a second end closure for the other end of said cylinder and having a gas outlet opening therethrough, means to rotate said cylinder about its axis, said end closures being stationary with respect to rotary motion of said cylinder, means communicating with said cylinder through said gas inlet opening for generating hot gases which travel through said cylinder and escape therefrom through said gas outlet opening, conveying means stationary with respect to the rotary motion of the cylinder and extending longitudinally from end to end of said cylinder therewithin and including a first flight travelling toward said first end closure and a second flight receiving materials from said first flight adjacent said first end closure and travelling toward said second end closure, means to direct materials onto said first flight adjacent said second end closure, said second flight discharging materials to the inner surface of said cylinder adjacent said second end closure, scoop means extending from end to end of said cylinder on the interior thereof for repeatedly elevating the materials and releasing the materials adjacent the top of the cylinder, downwardly inclined baffle means mounted above said conveyor flights for preventing the elevated materials from dropping back onto the conveying means, said cylinder being inclined downwardly toward said first end closure whereby the materials move toward said first end closure while being elevated and dropped, said first end closure having a material outlet opening for permitting the escape of the dried materials.

6. A drier for loose bulk materials including grains, sawdust, chopped forage, and the like, and comprising a horizontally extending cylinder having imperforate walls retaining said materials in said cylinder, a first end closure for one end of said cylinder and having a. gas inlet opening therethrough, a second end closure for the other end of said cylinder and having a gas outlet opening therethrough, means to rotate said cylinder about its axis, said end closures being stationary with respect to rotary motion of said cylinder, means communicating with said cylinder through said gas inlet opening for generating hot gases which travel through said cylinder and escape therefrom through said gas outlet opening, conveying means stationary with respect to the rotary motion of the cylinder and extending longitudinally from end to end of said cylinder therewithin and including an upper flight travelling toward said first end closure and a lower flight receiving materials from said first flight adjacent said first end closure and travelling toward said second end closure, means to direct materials onto said upper flight adjacent said second end closure, said lower flight receiving materials from said upper flight adjacent said first end closure and said lower flight discharging materials onto the inner surface of said cylinder adjacent said second end closure, scoop means extending from end to end of said cylinder on the interior thereof for repeatedly elevating the materials and releasing the materials adjacent the top of the cylinder, downwardly inclined baflle means mounted above said conveyor flights for preventing the elevated materials from dropping back onto the conveying means, said cylinder being inclined downwardly toward said first end closure whereby the materials move toward said first end closure while being elevated and dropped, and a material outlet opening in the lower section of said first end closure for permitting the escape of the dried materials.

7. A drier for loose bulk materials including grains, sawdust, chopped forage and the like, and comprising a horizontally extending cylinder having imperforate walls retaining said materials in said cylinder, a first end closure for one end of said cylinder and having a gas inlet opening thcrethrough, a second end closure for the other end of said cylinder and having a gas outlet opening therethrough, means to rotate said cylinder about its axis, said end closures being stationary with respect to rotary motion of said cylinder, means communicating with said cylinder through said gas inlet opening for generating hot gases which travel through said cylinder and escape therefrom through said gas outlet opening, conveying means stationary with respect to the rotary motion of the cylinder and extending longitudinally from end to end of said cylinder therewithin and comprising an upper flight travelling toward said first end closure and a lower flight travelling toward said second end closure, means to direct materials onto said upper flight adjacent said second end closure, said upper flight discharging materials onto said lower flight adjacent said first end closure, said lower flight discharging materials onto the inner surface of said cylinder adjacent said second end closure, scoop means extending from end to end of said cylinder on the interior thereof for repeatedly elevating the materials and releas' ing the materials adjacent the top of the cylinder, a stationary housing enclosing said conveyor flights and including a peaked roof for preventing the elevated materials from dropping back onto the conveying means, said housing being open at its end adjacent said first end closure and comprising at least one side wall of foraminous material, said cylinder being inclined downwardly toward said first end closure whereby the materials move toward said first end closure while being elevated and dropped, and a material outlet opening in the lower section of said first end closure for permitting the escape of the dried materials.

8. A drier for loose bulk materials including grain, sawdust, chopped forage and the like, and comprising an inclined cylinder having imperforate walls retaining therethrough, a second end closure for the other end ofv said cylinder and having a gas outlet opening therethrough, means to rotate such cylinder about its axis, said end closures being stationary with respect to rotary motion of said cylinder, means communicating with such cylinder through such gas inlet opening for generating hot gases which travel through such cylinder and escape therefrom through said gas outlet opening, conveying means stationary with respect to the rotary motion of the cylinder and extending longitudinally from end to end of such cylinder therewithin and including an upper flight of an endless conveyor travelling toward said first end closure and a lower flight travelling toward said second end closure, both said upper and lower flights extending through an aperture in said second end closure, said endsaid upper trough extending through said second end 7 less conveyor having spaced transverse pushers, an upper V trough containing said upper flight and a lower trough;

containing said lower flight, said upper trough extending through said second end closure from the point outside of the cylinder to a point short of said first end closure, said lower trough extending from a, point close to said first end closure to a point short of said second end closure, a hopper outside of said cylinder for the feeding material onto the outwardly extending end of said upper trough whereby said transverse pushers push the material along said upper trough until it drops onto said lower trough adjacent said first end closure, and then push the material back along said lower trough until it drops onto the interior of said cylinder.

9. A drier for loose bulk materials including grain, sawdust, chopped forage and the like, and comprising a horizontally extending cylinder having imperforate walls retaining said materials in said cylinder, a first end closure for one end of such cylinder and having a gas inlet opening therethrough, a second end closure for the other end of said cylinder and having a gas outlet opening therethrough, means to rotate such cylinder about its axis, said end closures being stationary with respect to rotary motion of said cylinder, means communicating with such cylinder through such gas inlet opening for generating hot gases which travel through such cylinder and escape therefrom throughsaid gas outlet opening, conveying means stationary with respect to the rotary motion of the cylinder and extending longitudinally from end to end of such cylinder therewithin and including an upper flight of an endless conveyor travelling toward said first end closure and a lower flight travelling toward said second end closure, both said upper and lower flights extending through an aperture in said second end closure, said endless conveyor having spaced transverse pushers, an upper troughcontaining said upper flight and a lower trough containing said lower flight,

closure from a point outside of the cylinder to a point short of said first end closure, said lower trough'extending from a point close to said first end closure to a point short of said second end closure, a hopper outside of said cylinder for the feeding material onto the out wardly extending end of said upper trough whereby said transverse pushers push the material along said upper trough until it drops onto said lower trough adjacent said first end closure, and then push the material back along said lower trough untilit drops onto the interior of said cylinder, scoop means extending throughout the interior of said cylinder, means to rotate said cylinder whereby said scoop means repeatedly tumble the material throughout the interior of the cylinder, said cylinder being downwardly inclined toward said first end closure whereby the tumbling material travels toward said first end closure, said .first end closure having a material outlet opening therethrough to discharge the materials, and

stationary housing means in said cylinder enclosing said conveying means and including a peaked roof above said upper flight to prevent materials being tumbled from dropping thereinto.

10. The construction set forth in claim 9 wherein said housing comprises an upper peaked roof above said upper flight within said cylinder and a second peaked roof above said lower flight within said cylinder, the space betweensaid upper trough and said lower roof. being open at the sides.

References Cited in the file of this patent V UNITED STATES PATENTS 299,683 Sawin June 3, 1884 1,644,779 Hamilton et a1 Oct. 11, 1927 2,132,972 Schmidt Oct. 11, 1938 2,746,865 Seltzer et a1. May 22, 1956 FOREIGN PATENTS 19,795 Great Britain .*1889.

Great Britain 1913 at least one of said v

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