US2346500A - Drying method and apparatus - Google Patents

Description

I R. c. MOORE DRYING METHOD AND APPARATUS April ll, 1944,

4 Sheet s-Sheet 1 Filed Jan. 26, 1942 W Gu INVENTOR. @CHHEO C. M0

ATTORNEY 5 April 11, 1944.

R. C. MOORE DRYING METHOD AND APPARATUS Filed Jan. 20, 1942 4 Sheets-Sheet 2 INVENTOR.

r n V W flaw/lea C/Vaaes 44% mm 941%! ATTORNEY 5 April 11, 1944.

DRYING METHOD AND APPARATUS Filed Jan. 20, 1942 MOORE 4 Sheets-Sheet 3 v I MM! Elan/zen CI M0025 April 1 1944. R. c. MOORE 2,346,500

DRYING METHOD AND APPARATUS Filed Jan. 20, 1.942 4 Sheets-Sheet 4 E mmw W g m6 m m w W 1 1 \i H m 5 h i m 8 W 4 WI A /,(M h m W. A 1/5. W e M m H JPN lk i .14. I1 w 5 W ATTORNEY$ Patented Apr. 11, 1944 DRYING METHOD AND APPARATUS Richard C. Moore, Painesville, Ohio, assignor to The (Joe Manufacturing Company, Painesville, Ohio, a corporation of Ohio Application January 20,1942, Serial No. 427,482

2i Claims.

.Thisinvention relates an improved method and apparatus for handling and drying various materials and especially suitable for handling and dryin materials in the form of tacky Particles such as crumbs, curds or grains of synthetic rubber.

'An object of my invention is to provide an im-' proved method and apparatus for handling and drying synthetic rubber crumbs or various other tacky materials in which the crumbs are .prevented from sticking together or coalescing while they are being advanced'to the drier and also during their passage through the drier.

Another object of my invention is to provide a novel method and apparatus for advancing crumbs of tacky material to a drier and starting the crumbs through the drier.

Still another object 01 thisinvention is to provide a novel method and apparatus for handling and drying tacky crumbs or the like involving the use of a foraminous or screen belt onto which the crumbs are deposited in a soapy liquid and wherein air discharged through the belt removes and dries the crumbs.

A further object of my invention is the provision of a novel method and apparatus for dryins crumbs of tacky material in which jets or streams of air are employed to agitate, dry and advance the crumbs in a manner such as to prevent the crumbs from sticking to each other and to the bottom and walls of the drier.

My invention also aims to provide an improved method and apparatus for drying crumbs oi. tacky material in which the drier has a foraminous or screen floor through which jets of heated air are discharged by reciprocating nozzles to maintain the crumbs substantially in suspension and to dry the same, and wherein air is caused to flow longitudinally through the heater for advancing the crumbs therealong.

Other objects and advantages of the invention will be apparent from the following description of the accompanying drawings, in which Fig. 1 is an elevational view with parts in section showing the supply end of my improved maillustrate theconnection oi the air supply piping with the reciprocating nozzle boxes.

Fig. 6 is a partial longitudinal sectional elevation further illustrating the reciprocating nozzle boxes.

Fig. '7 is a detached plan vlewoi the nozzle box at the delivery end of the feed conveyor, and

Fig. 8 is a transverse sectional view taken through this nozzle box on the line 8-8 of Fig. 7.

More detailed reference will now be made to the drawings for the purpose of describing my novel method and apparatus for handling and drying tacky crumbs and other materials, but it will be understood, of course, that the invention is not limited to the particular method and apparatus disclosed but includes all variations and modifications thereof coming within the scope oi the appended claims.

In Fig. 1 I show ahead box Ill and a conveyor ll extending between the head box and the receiving end of the drying unit II. The head box .contains a circuitous passage I3 leading to a discharge -chute or nozzle H which extends over the receiving end of the conveyor. The material to be dried is contained in a slurry which is supplied to the head box and is fed therefrom onto the conveyor l I through the chute or nozzle I4.

The material to be dried may be particles of synthetic rubber which may be in the form of crumbs, curds or grains of approximately oneeighth oi an inch in diameter and which are sticky or tacky in character after they have been removed from the slurry and washed. These tacky crumbs tend to adhere to any surface which they touch and also tend to adhere to each other or coalesce if the particles are piled up or otherwise come into contact with each other after they have been washed and before they have been dried. My method and apparatus is hereinafter described in connection with the drying of such synthetic rubber crumbs but the invention is not' limited in this respect and is applicable to various other materials.

The slurry which is brought to the head box In is in the form of a soapy solution, or any equivalent liquid, containing the crumbs of synthetic-rubber. The flow of the slurry through the circuitous passage l3 0! the head box and through the nozzle It to the conveyor may be controlled by varying the width of, or closing,

the passages l3a and l3b. These passages are controlled by the gates I30 and l3d which may beclosed by downward swinging of the lever i5.

Agitators is may be provided in the head box other foraminous material.

and may be suitably driven for agitating the,

slurry to prevent settling of the crumbs.

The conveyor ll comprises a suitable frame having rollers mounted thereon for supporting an endlessbelt 23 formed of wire screen or The rollers may include a roller 2! at the receiving end of the conveyor, rollers 22 and 22a at the discharge end, and a guide roller 22b for supporting the return section of the belt at an intermediate point of the conveyor. The discharge end of the conveyor is located at or adjacent the inlet open ing 24 of the receiving end of the drying unit i2. For a purpose to be presently explained the discharge end of the conveyor is so arranged that the portion 23a of the belt passing from the roller 22 to the roller 22a extends in a'forwardly and downwardly direction adjacent such opening of the drying unit. If desired the roller 22 may actually be located a short distance inside the receiving end of the drying unit l2. The belt 23 may be propelled by suitable driving means connected with one of the rollers such as the roller 22a which, in this instance, is connected with a speed reducing gear 25 by means of belts 26 and the speed reducing gear is driven by an electric motor 21.

When the slurry containing the crumbs of synthetic rubber is discharged through the nozzle onto the' moving belt 23 the soapy solution passes through the belt leaving the crumbs on top at a fair density of coverage but preferably such that the individual crumbs are not in contact with each other. A pan or tray 28 may be located beneath the section of the .belt nearest the nozzle so as to collect the soapy solution for further use. The slurry may be prevented from flowing over the side edges of the belt. 23 by providing the conveyor with endless deckle strips 30 which extend over the rollers 3| and 32 and travel with the belt to form retaining sides thereon.

of synthetic rubber, and for the purpose of removing some of this remaining water I may provide a suction box 45 beneath thebelt'23 at a point between the pan 38 and the roller 22; A discharge pipe 46 leading from the suction box 45 may be connected with a suction fan or other vacuum producing device so that air and water will. be removed from the suction box and a flow of air downwardly through the belt will be produced to remove additional-rinse water from the rubber crumbs.

For removing the crumbs from the belt 23 and starting them through the drying unit 12 I provide means for discharging air through the belt.

with suflicient velocity and volume to lift or blow the crumbs therefrom and carry or propel them forwardly and upwardly into the receiving end of the drying unit in a separated or scattered condition. This air discharging means may be in the form of a nozzle box 48 extending transversely of the conveyor beneath the for.-

- wardly and downwardly extending section 23a and having a plurality of laterally elongated nozzles 49 located relatively close to the underside of the belt for discharging blasts of air there-' through.

In removing the rubber crumbs from the belt 23 and starting them through the drying unit i2,- the useof an air blast for this purpose which will also cause a rapid surface drying of the crumbs is highly important because this surface drying reduces the degree of stickiness of the surface of the crumbs to a sufilcient extent to prevent them from adhering to each other or toportions and surfaces with which they may come in contact in the drying unit. I prefer to use heated air for this blast because the surface drying is accomplished more effectively. At this stage the crumbs are in a relatively wet condition and since this drying and conveyor-unloading blast is in contact with the crumbs for only a very short time, it can be of a relatively high temperature without causing heat It is desirable to wash the synthetic rubber.

crumbs to free them 'of the soapy solution before the crumbs are dried. For this purpose I provide a plurality of spray units 33 and 34 located over the conveyor and spaced thereal'ong in the direction of travel of the belt 23. Clean soft rinse water is supplied to the second spray unit 34 through piping 35 and through a heater 36 containing a steam coil or provided with other appropriate heating means. The clean rinse water which is discharged by the unit 34 washes the synthetic rubber crumbs and after passing through the conveyor belt is collected by the pan 31. The rinse water may continue to drain from the belt and the rubber crumbs thereon as the belt travels away from the spray unit 34 and such additional drainage of rinse water may be collected by the plan 33. The used rinse water collected by the pans 31 and 33 may be returned to a tank 33 in which itisheated by a steam coil 40 or other suitable heating means The passing through the layer of crumbs and the belt 23 the rinse water is collected in a pan 43 and can be disposed of in any desired manner.

As the-belt passes beyond the pan 33 some of the rinse water will still be clinging to the crumb damage -to the crumbs.v For heating the air for this blast I provide a heater 50 in the pipe 5| leading to the nozzle box 48. The air to be discharged through the nozzles 49 is drawn through a supply pipe 52 by a blower 53 which forces the air through the heater 5'! and the pipe 5| to the nozzle box '48. The blower may be driven by suitable power means such as the electric motor 54.

The drying unit i2 comprises an elongated housing 55 having a drying tunnel 56'extending longitudinally therethrough. The bottom of the tunnel is formed by a stationary screen or perforated plate 51 which is suitably supported in the housing at a point above the floor line 58. It is desirable to keep the crumbs of synthetic rubber in an agitated condition and more or less in suspension from the time that they have been blown off the belt 23 until they arrive at the delivery end of the tunnel. For this purpose, I provide a plurality of air boxes or plenum chambers 60 which are spaced apart longitudinally of the tunnel and extend transversely thereof beneath the screen floor 51. As shown in Fig. 6 these boxes have a plurality of air discharge slots or nozzles 6i formed in the top thereof so as to lie adjacent the underside of the screen bottom or tunnel floor 51. Each of the boxes 60 has an inlet pipe or connection 62 through which the heated air may be supplied to the box with sufiicient pressure to cause blasts or streams of air to pass ing end of the, drying tunnel 56 they are separated and partially dried by the air blast from the box 4|, as mentioned above, and then fall toward the screen. The crumbs may or may not actually fall on the screen 51 because as they approach the screen they are acted upon 'by the blasts of heated air being discharged upwardly bythe slots or nozzles. 6| and these blasts of air lift and agitate the crumbs in the drying tunnel and maintain them substantially in suspension.

To prevent any substantial amount of the crumbs from remaining at rest on the screen 5'! for more than a very brief interval, it maybe desirable to reciprocate the boxes 60 longitudinally of the drying tunnel 56 so that the blasts of air discharged by the nozzles 6| will intermittently pass through all portions of the screen. To thisend I may support the air boxes 66 on, a suitable frame 63 having side rails 63awhich are supported at spaced points therealong by rollers 64 and reciprocate the frame 63 by means of a rod or link 65 connecting the frame with a crankshaft oreccentnc 66 of a motor driven unit 61.

The stroke of the connecting rod or link should be such that the nozzle travel will be slightly greater than the spacing between adjacent nozzles so that there will be no dead spots on the screen 51. The rate of reciprocation of the air boxes may be relatively rapid so that any rest period of the crumbs on the screen will be very brief.

To provide for the removal of air from the drying tunnel 56 I employ a longitudinally extending plenum chamber-69 in the upper portion of the housing 55 and from which air can be rapidly withdrawn by a plurality of blowers I0 spaced along the top of the drying unit I 2.

The plenum chamber 69 is separated from the, drying tunnel 56 by a perforated plate or screen II which permits the air to pass upwardly into the plenum chamber and causes the air to enter the plenum chamberat a substantially uniform face velocity over the entire area of the screen. The air discharged through the nozzles 6| of the boxes 60 should have suflicient velocity and volume to prevent the crumbs from settling on the screen bottom or floor 51 and to maintain them more or less in suspension in the tunnel 56. Likewise the flow of air through the screen H into the plenum chamber 69 should be such that its velocity will not be so great as to hold the crumbs against the screen but will permit them to fall back into the tunnel. To obtainthe desired air velocity and volume through the screens 51 and H I may pro'-' vide suitable control dampers at appropriate points such as the dampers 62a in the inlet connections 62 of the air boxes 60. When streams of heated air satisfying -the above requirements are supplied by the nozzles 6i and traverse the drying tunnel 56 they will impart a more or less dancing movement to the crumbs during which the crumbs are kept more or less in suspension between the screens 51 and H and are subjected to an eifective drying action.

The air which is supplied to the boxes 60 may be recirculated air and therefore the discharge nozzles 12 of the blowers 16 may be connected to the inlet openings 62 of the boxe by means of the relatively. large pipe 73. The lower ends of the pipes 73 may be flattened and flared out laterally in the longitudinal direction of the drying tunnel 56 so that each of the pipes 13 -may supply air to two or more of the longitudinally spaced air boxes 60. Since the air boxes are arranged to be moved back and forth in the drying tunnel 56 it is necessary to provide the air supply connections 62 with a flexible sleeve 15, or equivalent means, which will permit these boxes to move relative to the pipes 13 while the air supply is being maintained.

a The drying action of the air delivered by the nozzle 6| will be much more rapid if the air is heated and I, therefore, provide a heating unit I6 in each of the air supply pipes 13. A more balanced and satisfactory arrangement is obtained for the piping and the heaters 16 if the discharge pipes-13 are arranged alternately on opposite sides of the housing of the drying unit as shown in Fig. 3. I also find that a more uniform and satisfactory flow of air across the drying tunnel 56 from the nozzle 6i i obtained when approximately one-half of the boxes are supplied with air from one side of the drying unit and the remaining boxes are supplied with air from the opposite side of the unit.

The air which is supplied to the box 46 by the blower'53 for use in blowing the crumbs ofl the belt 23 may also be recirculated air and, accordingly, the inlet pipe 52 leading to the blower 53 may be connected with the plenum chamber 69 as shown in Figs. 1 and 2.

In order to produce a movement of the crumbs along the tunnel 56 while they are being subjected to the drying action of the air discharged by the nozzles 6|, I cause a flow of air longitudinally through the tunnel which gradually move the dancing crumbs to the discharge end of the tunnel and into the collecting device 16. This collecting device may be a separator of the kind known as a cyclone separator and may have .a hopper bottom 16a from which the collection of dried crumbs may be discharged onto a conveyor 19 for moving the crumbs to a desired point of use or storage. separator may b connected with the intake of a blower 80 which returns the air to the receiving end of the drying tunnel 56 through the pipe 6|. The rate of advance movement of the crumbs in the drying tunnel 56 may be coner 84 of the exhauststack 83a to be referred to hereinafter. In controlling the operation of the drying unit l2 it may be desirable to permit a sufllcient quantity of the air discharged by the fans 16 to escape to atmosphere to 0am oifthe water vapor removed from the material and, for this purpose, I provide the exhaust stacks 63 which are provided with adjustable dampers 84. A similar exhaust stack 83a may be provided on the pipe 8l adjacent the discharge connection ofthe fan 80. The loss of fine particles or crumbs of synthetic rubber thrugh the exhaust stack 63a may be prevented by providing a filter bag or other suitable filtering means 65 in this exhaust outlet which will separate out and retain the fine particles.

The rate of movement of the crumb along the drying tunnel 56 .is also regulated more or less automatically by reason of the fact that the The upper end of the by the longitudinal air flow produced by the blower 80, whereas the particles which remain closer to the screen 51 will not be acted on to will-therefore travel through the tunnel more slowly. These different rates of movement are desirable because the larger particle usually require a longer drying period.

To prevent the crumbs from sticking to the side walls 81 of the drying tunnel I may provide these side walls with vertically spaced longitudinally extending slots or louvers 88 so that scouring jets or streams of air will flow upwardly in the drying tunnel along the side walls. The wall 81 of the drying tunnel may be spaced inwardly from the side walls of the housing 55 to provide air spaces or plenum chambers 89 therebetween. The air to be discharged through the slots or louvers 88 may be heatd air supplied to the plenum chambers 89 from the pipes F3. The amount of air supplied to the'plenum chambers 89 for this purpose may be controlled by suitable dampers or valves 90.

-When the crumb approach the discharge end of the drying tunnel they will be relatively dry and since they may be at a relatively high temperature it may be desirable to subject them "to a cooling action. For this purpose I may supply relatively cool air to one or more of the air boxes 80 located nearest the discharge end of the drying unit l2. Cool air may be supplied to these boxes by means of a blower 9i and a pipe 92 connecting the boxes with such blower. The intake opening 93 of this blower may be open to atmosphere so that relatively cool at-' mospherio air will be supplied to the boxes through the pipe 92.

The temperature of the heated air which is supplied to the boxes t8 and 60 and to the plenum chambers 89 should be such that it will bewhigh enough to cause a rapid drying of the synthetic rubber crumbs but must not be so high as to cause damage to the crumbs. The air may be at a temperature of approximately 350 F. although it may be at a considerably higher temperature it such higher temperature can be used without damage to the material being dried. In heating the air to the desired temperature steam or other heating medium may be supplied to the radiators or heatexchangers 50 and It by pipe connections 94.

The supply of heating medium to the heaters may be regulated in accordance with the temperature to which it is desired to heat the air and such regulation may be accomplished by providing automatic valves 95 in the supply pipes 04 and which valves are operated in response to the control junctions exercised by thermostats 96 appropriately located in the air pipes I and II.

From the foregoing description and the accompanying drawings it will now be readily understood that I have provided. a novel method and apparatus fordrying various materials in the form or crumbs, cur ...grains or other'par- 'ticles and which is especially suitable iorhandling and drying crumbs of synthetic rubber or other tacky particles.

While I have illustrated and described my method and apparatus in more or less detail it will be understood, of course, that I do not wish' to be limited to the particular method steps and structuraldetails herein disclosed but regard my invention as including all variations the same extent by the longitudinal air flow and and modifications coming within the scope of the appended claims.

Having thus described my invention, 1 claim: '1. In a method of drying, the steps of advancing particles of the material to be dried on a foraminous belt to the receiving end of a drying tunnel, and discharging a blast of air through the belt from' the under side thereof and with a direction and velocity such that it removes the particles from the belt and carries them into said receiving end of the tunnel.

2. In a method of drying, the steps of advancing particles of the material to be dried on a foraminous belt to the receiving end of a drying tunnel, and discharging a blast of heated air through the belt from the under side thereof and with a direction. and velocity to lift and separate the 'particlesand carry them into said receiving end of the tunnel.

3. In a method of drying, the steps of advancing particles of the material to be dried on a foraminous belt and causing the belt to travel forwardly and downwardly at the receiving endof a drying tunnel, and discharging a blast of heated air throughthe forwardly and downwardly extending portion of the belt in a direction to remove the particles from the-belt and carry them upwardly and forwardly into said receiving end of the tunnel.

4. The method of treating crumbs of tacky material which comprises advancing the material while in contact with a soapy liquid, depositing the material on a screen belt so as to separate it from the liquid, washing the material while on the belt to remove the soapy liquid, advancing the material by movement of the belt to a point adjacent a drier, and discharging air through said screen belt from the under side thereof and with sumcient velocity to remove the crumbs from the belt 'and carry them into the v them substantially in suspension, and causinga flow of air longitudinally through the tunnel to advance the particles therealong.

6. The method of treating crumbs of tacky material which comprises discharging soapy .liquid containing such crumbs onto a foraminous belt so as to separate the crumbs from the liquid,'washing the crumbs while on said belt, advancing the material to a drier, discharging air through the belt from the under side thereof and with a direction and velocity such as to blow the'crumbs from the belt and into the drier, discharging streams of heated air upwardly in the drier to dry the crumbs and maintain them substantially in suspension, and causing a flow oi air in the drier for advancing the crumbs therein.

7. The method 01' treating crumbs of tacky material which comprises discharging soapy liquid containing such crumbs onto a foraminous belt so as to separate the crumbs from the liquid, washing the crumbs while on said belt, advancing the material to a drier, discharging air through the belt-from the underside thereof and with a direction and velocity such as to'blow the crumbs from the belt and into the drier,

the drier through nozzles spaced therealong to' dry the crumbs and maintain them substantially in suspension, reciprocating said nozzles while said air streams are being discharged, and causing a flow of air in the drier for advancing the material therein.

8.' The method of treating crumbs of tacky material which comprises discharging soapy liquid containing such crumbs onto a foraminous belt so as to separate the crumbs from the liquid, washing the crumbs whileon said belt, advancing the crumbs to a drier, discharging air through the belt from the under side thereof and with a direction and velocity such as to blow the crumbs from the belt and into the drier, discharging'streams of heated air upwardly in the drier to dry the crumbs and maintain them substantially in suspension, causing a flow of air in the drier for advancing thecrumbs therein, and cooling and collecting the dried crumbs.

9. In drying apparatus, a drying tunnel, a movable foraminous belt arranged to carry the material to be dried to a point adjacent one end of said tunnel, and means for discharging air through said belt from the under side thereof and with a direction and velocity such as to lift the material from the belt and carry it into said tunnel.

10. In dryin apparatus, a drying chamber, a movable foraminous belt arranged to carry the niaterial to be dried to a point adjacent an openand drying said material; means for reciprocat- V ing said nozzles longitudinally of the tunnel, and

ing into said chamber, and means for discharging heated air through said belt from the underside thereof and with a direction and velocity such as to blow the material from the belt and into saidchamber and cause separation and drying of the individual particles of said material.

11. In drying apparatus, a drying tunnel, a movable foraminous belt arranged to carry the material to be dried to a point adjacent one end of said tunnel, and means for discharging air through said belt so as to lift the material therefrom and carry it into said tunnel, means for discharging heated air upwardly in saidtunnel at spaced points therealong for agitating and drying said material and maintaining it substantially in suspension, and meansfor causing a'flow of air longitudinally of the tunnel for advancing the material thercalong.

12. In drying apparatus, a drying tunnel ha ing receiving and discharge ends and a continuous longitudinally extending substantially flat screen bottom therebetween, means for delivering material to be dried into the receiving end of said tunnel, means at the discharge end means for causing a flow of air longitudinally through the tunnel above said bottom for ad- .vancing the material along the tunnel.

14, In combination with a drier having an opening at one end thereof, a foraminous belt arranged'so that a portion thereof extends downwardly and forwardly in front of said opening, and means for forcing air through said down- -wardly and forwardly extending portion of the belt so as to blow material to bedried from the belt and into the drier.

15. In drying apparatus, a drying tunnel having side walls and a continuous longitudinally extending substantially fiat screen bottom, means for supplying material to be dried to said tunnel at one end thereof, means at the other end of the tunnel adapted to receive the'dried material, means for discharging heated air upwardly through said screen bottom for drying the material and substantially maintaining the same in suspension above said bottom, the side walls of said tunnel having louvers therein arranged to direct air over the surfaces of said walls to prevent the material from sticking to said walls, 1

means providing plenum chambers at the sides of said tunnel for supplying air to said louvers,

and means for causing the circulation of an additional supply of air longitudinally through the tunnel above said screen bottom and in a direction from said one end towards said other end for advancing the material in suspension along the tunnel.

16. In drying apparatus of the character described, an elongated housing having a drying tunnel therein, means at one end of the housing for blowing the material to be dried into the receiving end of the tunnel, means for blowing air upwardly in the tunnel at spaced points therealong for agitating and drying the material, the

side walls of said housing being spaced from the sidewalls of the drying, tunnel to provide plenum chambers therebetween and the side walls of the tunnel having longitudinally extending louvers for discharging air upwardly in the tunnel to prevent the material from sticking to the tunnel side walls, and means for forcing air into said a plenum chambers.

17. In drying apparatus, a housing having an elongated drying tunnel provided with a foramiadapted to receive the dried material, a plurality of nozzles beneath said screen bottom and spaced longitudinally of the tunnel, means for supplying heated air to said nozzles to be discharged thereby through said screen bottom for drying the material and substantially maintaining the nous bottom, a plenum chamber extending longitudinally in the housing and communicating with the drying tunnel along the means for blowing particles of the material in be dried into the tunnel at the receiving end thereof, a plurality of nozzles spaced along the tlmnel beneath said bottom and arranged to blow air upwardly through said bottom for agitating and drying the material, a blower operable to withdraw air from said'plenum chamber and to supply air under pressure to said nozzles, and means for heating the airsupply to said nozzles.

18. In drying apparatus, a housing having an elongated drying tunnel provided with a foraminous bottom, a plenum chamber extending longitudinally in the housing and communicating with the drying tunnel along the top of the latter, means for blowing particles of the material to be dried into the tunnel at the receiving end thereof, a plurality of nozzles spaced along the tunnel beneath said bottom and arranged to blow air'upwardly through said bottom for agitating and drying the material, a blower operable to withdraw air from said plenum chamber and to supa of the latter,

ply air under pressure to said nozzles, means for heating the air supply to the nozzles, air diselongated drying tunnel provided with a foraminous bottom, a plenum chamber extending longitudinally in the housing and communicating with the drying tunnel along the top of the latter, a wire belt movable to convey the material to be dried to a point adjacent the receiving end of said tunnel, a nozzle arranged to discharge air through said belt for blowing the material into the receiving end of the tunnel, a plurality of nozzles spaced along the tunnel beneath said foraminous bottom and arranged to blow ahupwardly through said bottom for agitating and drying the material, means for withdrawing air from said plenum chamber and supplying air under pressure to" the nozzles, mean-s for heating the air supply to the nozzles, air discharge means at the receiving end of the tunnel arranged to discharge air longitudinally through the tunnel for advancing the material therealong, a separator at the delivery end of the tunnel adapted to receive the dried material, and a blower operable to withdraw air from the separator and to supply air under pressure to said air discharge means.

20. In drying apparatus, a housing having an nous-bottom, a plenum chamber extending longitudinally in the housing and communicating with the drying tunnel along the top of the latter, a wire belt movable to convey the material to be dried'to a point adjacent the receiving end of said tunnel, a nozzle arranged to discharge air through said belt for blowing the material into the receiving end of the tunnel, a plurality of,

nozzles spaced along the tunnel beneath said foraminous bottom and arranged to blow air upwardly through said bottom ior agitating and drying the material, means for withdrawing air from said plenum chamber and supplying air under pressure to the nozzles, means for heating the air supply to the nozzles, means for thermostatically controlling said heating means to maintain said air supply at a desired temperature, air discharge means at the receiving end of the tunnel arranged to discharge air longitudinally through the tunnel for advancing the material therealong, a separator at the delivery end of the tunnel adapted to receive the dried material, and a blower operable to withdraw air from the sepelongated drying tunnel provided-with a fox-amiaratcr and to supply air under pressure to said air discharge means.

21. The method of drying crumbs of tacky ma- I teria'l which comprises advancing the crumbs on a foraminous belt to the receiving end of a drier in a relatively wet condition, discharging a blast of drying air through the belt from the under side thereof with a velocity, direction and volume to remove the crumbs from the belt and to reduce their surface tackiness sufliciently to prevent the crumbs from adhering and to carry the crumbs into said receiving end of the drier.

RICHARD C. MOORE.

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