US2316459A - Rotary drier - Google Patents

Description

April 13, 1943. H. SCHMIDT ETAL ROTARY DRIER Filedl July s, 1939 4 sheets-smet 1 5% ATT April 13, 1943.

H. L SCHMIDT ETAL 2,316,459

ROTARY DRIER Filed July 5, 1939 v 4 Sheets-Sheet 2 #ff/w i ATTORNEY- April 13, 1943. H. L. SCHMIDT ETAL l OTARY DRIER Filed July 5,V 1959 4 sheets-sheet s ATTORNEY. Y `l PIil 13, 1943. H. L SCHMIDT ErAL ROTARY DRIER Filed July 3, 1959 4 Sheets-Sheet 4 Patented Apr. i3, i943 r cette ROTARY BEHEER Harlow L. Schmidt and Henry Q. French, assignors to The Heil Co.,

waukee, Wis.,

9 Claims.

Our invention relates in general to improvements in the art of dehydrating bulk materials, and relates more particularly to various improvements in the construction and operation of rotary driers of the type wherein solid particles such as hay mixed with heated gases such as air, are constantly urged through a revolving drum, the dried material being separated from the heating medium at the discharge end of the assemblage. p

Generally defined, an object of our invention is to provide various improvements in the con. struction of rotary drierawhereby the cost of construction and operation thereof is reduced to a minimum while the eiiiciency is enhanced to a maximum.

Some of the more important specific objects of the present invention are as follows:

To provide adrier wherein the material being treated is mixed with the drying medium and the mixture is drawn through the drying zone in a continuous stream, and in which fresh material may be introduced into the advancing stream of mixture without admitting excessive quantities of cold air to the drying zone.

To provide an improved drier assemblage wherein the dried material may be delivered direct from the zone of separation of the drying medium, or only after final cooling and removal of foreign objects such as stones or metallic particles from the nalproduct.

the present invention will be apparent from the following detailed description.

A clear conception of the several features constituting the present improvement, and of the mode of constructing and of operating rotary drier installations embodying the invention, may V of Fig. 2, but showing the purifier inactive, and

the parts adjusted for direct delivery of the product;

Fig. 4 is a side elevation of the delivery end of the improved drier installation, showing the'parts in a position corresponding to Fig. 2;

Fig. 5 is an end view of the drier installation looking toward the delivery end thereof;

Fig. 6 is a further enlarged longitudinal centrai vertical section through fragments of the drier drum, showing details of the air cooling To provide improved instrumentalities for protecting the various elements of a drying unit, against deterioration due to exposure to the weather and excessive heat.

To provide a self-contained complete rotary drier installation which is neat and compact in appearance, which is readily transportable and installable, and which may be operated with minimum power consumption.

To provide an improved feeder adapted to deliver uniform quantities of material to a drier drum regardless of regularities in the primary supply, and which is safeguarded against possible damage due to overfeeding.

To provide an improved fan and power unit housing for rotary driers, which may be conveniently associated directly with the drier drum outlet and thus produces a compact installation adapted to be readily assembled.

To provide an improved automatic cooling system for the material agitating flights of a revolving drum drier or the like, whereby the life of the drum may be materially prolonged.

These and other objects and advantages of system;

Fig. 7 is a part sectional end view 0f the inlet end of the drum of Fig. 6, the section beingtaken along the line 'l-i;

Fig. 8 is a perspective view of the raw material feeder which communicates with the drum inlet;

Fig; 9 is a longitudinal vertical section through the raw material feeder;

Fig. 10 is a transverse section through the feeder of Fig. 9, taken along the line lll-Ill;

Fig, 11 is a fragmentary section similar to that of Fig. 9, showing the conveyor gate in action; and

Fig. 12 is an enlarged outside view of a fragment of the feeder showing a detail of construction thereof.

While our invention has been shown and described herein as being specifically applied to a rotary drier wherein material such as green hay is adapted to be drawn by suction along a circuitous path through the revolving drum, it is not the intent to thereby unnecessarily restrict the scope of utility of the improvement.

Referring to the drawings, the improved drier installation illustrated therein comprises in general a horizontally elongated externally insulated rotary drying drum ls having an inlet is atv Y' one end and an outlet I1 at its opposite end, the drum being provided with end tires I8 cooperable with rollers I9 to rotatably support the same; a feeder 29 and a furnace 2| associated with the inlet end of the drum I and cooperating with the drier inlet i6 to constantly introduce a mixture of raw material and heated gas into the drying zone 22; a dry material discharge housing 23 and a gasseparator 24 associated with the discharge end of the drum I5 and having therein a main fan 25 cooperating with the outlet I1 to constantly withdraw the mixture of treated material and spent heating medium from Within the drum I5; and mechanism including a motor 90 enclosed within the housing 23, for rotating the fans, revolving thedrum I5, and actuating the feeder 2U.

The improved rotary drying drum in which the circuitous drying passage or zone'22 is connned, has therein an inner central cylindrical shell 21 communicating with the inlet I6 and pro- CII vided with internal longitudinal hollow nights 28,

and also has an intermediate shell 29 mounted therein between the shell 21 and the outer drum I5, see Figs. 6 and 7. The intermediate shell 29 and the drum I5 are also provided with internal longitudinal nights 3U, 3| respectively; and the discharge end of the inner shell 21 is spaced from a partition 32 mounted within the shell 29 in spaced relation to the outlet I1, while thedischarge end of the intermediate. shell is spaced from the inlet end head of the drier drum, thereby providing the circuitous passage. The parti'- t-ion 32 is provided with a cone 33 on one side thereof for denecting the stream of mixed solids and gases from the inner shell 21 into the intermediate shell 29, and has a cone 34 on its opposite side for deflecting the departing mixture through the outlet I1. The overhanging ends of the shells 21, 29 are mounted for free expansion longitudinally of the drum I5; and the hollow nights 28 within the shell 21 have their ends adjacent the cone 33 open while their opposite ends 35 are closed, but communicate through ports 36 with an annular chamber 31 which in turn is in open communication with the ambient atmosphere through ports 38. This construction of the nights '28 causes a constant circulation of relatively small quantities of cooling air therethrough during normal operation of the drier and protects these nights 28 against rapid deterioration due to exposure thereof to the hot gases entering the drying zone 22.

The improved special feeder 20 which is cooperable with the drier to insure uniform admission of an uninterrupted supply of raw material to the drying zone 22, is shown in detail in Figs. 8 to 12 inclusive, and comprises an elongated inclined casing 39 having a transverse partition 40 therein, the casing being provided at its lower end with an inlet hopper 4I and at its upper end with a downwardly directed delivery passage 42 communicating directly with the drier inlet I6; and an endless conveyor 43 having an upper stretch movable along the partition and being provided with a series of materialadvancing nights 44. The endless conveyor 43 coacts with lower sprockets 45 mounted on a shaft which is .journaled in adjustable lower bearings 46, and

also coacts with upper sprockets 41 carried by an upper drive shaft 48 connected by chain gearing 49 to a counter shaft 50 having a clutch 5I associated therewith. The clutch 5I is operable to drivingly connect the counter shaft 50 with a sprocket 52 which is constantly driven by a 75 chain 53 coacting with another, sprocket 54 rotatable by one of the drum carrying rollers I9, see Figs. 8 and 10.

The conveyor 43 is movable in the direction indicated by the arrow in Fig. 9, and a curved sealing plate 55 which is swingably suspended from a pivot shaft 56 coacts with the lower conveyor stretch and has a nat portion of. sufficient length to span the gaps between three successive nights 44. The swinging lower end of the sealing plate 55 is adapted to be adjusted toward and away from the lower conveyor stretch by means of slotted elements 51 coacting with laterally projecting pins 58 on the plate, and nuts 59 coacting with threaded extensions 60 on the elements 51 and with nanges on the casing 39. as shown in Figs. 9-and l2. With this assemblage, the plate 55 is free to gravitate toward the lower inclined wall of the casing 39 and to thus urge the lower nights 44 against this wall, but if an obstruction causes the lower conveyor stretch to move upwardly, the pins 58 will ride upwardly within the slots in the elements 51 and will thus avoid damaging the conveyor 43.

A somewhat similar sealing plate 6I is also provided at the top run of the conveyor 43, the plate 6| being swingably suspended from a pivot shaft 82 and having side walls and a cover 83 associated therewith to form a movable box, see

Figs. 9, 1o, and 11? The pate el also has a est portion which is adapted to span the gaps between three successive nights 44, and which is cooperable with the tops of the upwardly advancing nights of the upper conveyor stretch to' normally provide a seal. The box assemblage is swingable by gravity toward the conveyor nights. but may be automatically elevated'by excessive loads admitted to the conveyor 43 as in Fig. l1, and is also provided with a handle 64 for manual swinging. The top of the conveyor casing 39 may alsobe provided with.an inspection slide or door 65 located between the hopper 4| and the seal plate 6|, and another door 86 may be provided at the upper end of the casing 39 for inspection and air admission purposes.

The furnace 2| for supplying heated gases to the drying zone 22 through the inlet I6, may be either oil or gas nred, and is adapted to deliver the heating medium in swirling condition toward the inlet I6 and beneath the feeder delivery passage 42. The gravitating solids are thus spread and intimately mixed with the gaseous heating medium, and the temperature of this mixture may be modined by admitting regulated quantities of tempering air past the door 66. 'Ihe furnace 2| may be readily detached from the drum I5 and feeder 20, and the feeder 20 may likewise be readily detached from the drum I5, so that the heating, feeding and drying units of the installation may be conveniently handled for shipment and installation.

The improved dry material discharge housing 23 which also serves to support the separator 24 and to enclose the power plant and auxiliaries, is shown in detail in Figs. 1 to 5 inclusive, and comprise's three adjoining compartments 61, 68, 69 all forming part of the housing 23. The inner com- 24. This separator a central upper gas outlet, and in which the separated heavy solids or particles gravitate toward a lower outlet opening 1 I. The main fan 25 is mounted upon one end of a shaft 12 which passes entirely through the housing 23 axially of the drum I5, and the opposite end of this shaft has an auxiliary fan 13 mounted thereon and is also provided with a driving pulley 14, see Figs. 4 and 5.

The intermediate compartment 58 of the housing 23, has a downwardly directed iixed spout 15 therein which communicates directly with the separator outlet opening 1 i, and below this spout 15 is located an adjustable by-pass chute 16 and a heavy particle separator and nal cooling conduit 11, see Figs. 2 and 3. The chute 16 is rectangular in transverse cross-section and is slightly longitudinally tapered, and is moreover swingably adjustably suspended by a hinge 18 so that the chute will normally tend to assume a position as indicated in Fig. 2, in vertical alinement with the spout 15. The chute 16 may be provided with a latch or other means for positively holding it in vertical position, although the suction normally existing therein will tend to maintain this chute in such position. The front of the chute 16 is provided with a, normally closed sight opening 16, and may be 'swung about its suspension hinge 18 into the position shown in Fig. 3, whereupon material passing through the chute 16 may be discharged at the front of the compartment 68 directly from the separator 24. The medial portion of the inclined separator and cooling conduit 11 is upwardly open and is normally disposed in direct vertical alinement with the open lower end of the chute 16, and an adjustable baffle plate 50 attached to the front wall of the housing 23 extends toward the conduit axis and may be readily adjusted to various angular positions about a pivot 8| in order to vary the velocity of the flow. The lower end of the conduit 11 has an opening which may be closed by a cover 82, but the cover 82 may be disposed in open position as in Fig. 2 when the chute 16 is in vertical position. Above the medial upper opening in the inclined conduit r1, is a exea downwarmy extending bane wan 83, and the upper end of this conduit 11 is curved laterally and extends into the outer compartment 69 axially of the shaft 12.

The outer compartment 69 of the housing23 forms an enclosure for the auxiliary fan housing 84 within which the fan 13 is confined, and the axial inlet opening 65 of the fan 13 communicates directly with the separator conduit 11 while the peripheral tangential outlet 86 thereof communicates with a iinal delivery pipe 81 which may lead to any desired storage space or bagging zone.

The housing compartment 69 may also be provided with front and rear inspection doors 88, 89, respectively, and besides enclosing the auxiliary fan, this compartment 69 also houses an electric motor 36 which is operatively connected to the fan driving pulley 14 by a belt 9|. The motor 90 may also be drivingly connected in any suitable manner, with a universal driving connection 92 associated with one of the drum supporting rollers i9 through suitable reduction gearing located within an auxiliary housing 93, so that operation of the single motor Si) will produce simultaneous operation of the fans 25, 13, drum I5, and :feeder 28. The rear door 89 is exposed to both compartments 68, 89, and is provided with a screen as shown in Fig. 2, for permitting passage of atmos= pheric air to the ian 1t. The separator 24 may be readily detached from the housing 23, and the housing 23 with its contents may be readily detached from the drum l5, for shipment, and the entire assemblage may therefore be conveniently handled in the form of segregated units for transportation, but may also be quickly assembled into a complete installation.

When the drier installation'has been properly constructed and assembled, and the motor 90 is placed in operation, the fans 25, 13 are rotating,

the drum I5 is revolving, and the feed conveyor 43 may be placed in operation by manipulation of thel clutch 5|. When the clutch 5| has been thrown into active position, the upper ilights 4 of the endless conveyor will be advancing upwardly along the partition 40, and any material deposited within the hopper will naturally be carried upwardly toward the discharge openings 42 and deposited through this opening into the conduit leading `from the furnace 2|. During normal operation of the furnace 2|, hot gases of combustion mixed with heated air are being delivered with a swirling motion through the drier inlet I6, and the bulk material which is being 25 discharged in a constant stream through the outlet 42, will be mixed with the swirling. hot gases, and the mixture will advance through the drier due to the suction created by the main fan I 25 adjacent the drier outlet |1. During its passage through the drier drum l5, the solid particles of the mixture will be constantly showered across the interior of the shell 21 by the revolving flights 28, and the particles are ultimately drawn past the cone 33 into the intermediate shell 29 35 where the solid particles are further showered across the stream of hot gases. From the end of the shell 29, the mixture passes into the outer annular space Where the revolving flights 3| further shower the solid particles and agitate the mixture, and the nally treated material is ultimately discharged through the outlet I1 along the cone 34. The fan 25 then propels the mix-l ture of solids and gas through the main separator 24 wherein the spent gases of combustion and heated air are separated from the dry material, and the latter is discharged through the spout 15.

If the chute 16 is disposed as shown in Fig. 3, the dried material is by-passed to the exterior of the housing 23. If, however, the chute 16 is disposed as shown in Fig. 2, the dried material is drawn through the inclined conduit 11 and upwardly through the fan 13 where it is cooled and eventually delivered through'the pipe 81. During passage of the solids into the conduit 11, the abnormally heavy particles such as stones and metallic particles, are separated by gravity and flow downwardly and out of the lower end of the conduit 11. The lighter dried product passes upwardly past the baffle 83 and through the fan 13, and is thoroughly cooled during this passage.

While the drier installation is operated in this manner, it is unnecessary to attempt to regulate the quantities of fresh material which are admitted to the hopper 4|. The upwardly advancing iiights 44 will withdraw quantities of material' from the hopper 4|, and if the quantities thus withdrawn project over the upper extremities of the upper flights 44, the shut-oir plate 6| will be elevated slightly and will tend to spread the material over the conveyor. The plate 6| will function, however, to constantly maintain an air sealV 'between the upper ights 44 and the 'lower face of the plate, thus preventing undesirable entry of fresh air into the drying zone along the upper stretch of the conveyor 43. Simultaneously with this automatic functioning of the upper plate 6|, the lower plate 55 will cooperate with the lower flights 44 of the conveyor to seal the passage of air along the lower stretch of the conveyor. In this manner excess quantities of fresh air are absolutely prevented from entering the drying zone, and if it is desired to admit small quantities of tempering air to this zone, then the door 66 may be adjusted.

From the foregoing detailed description it will be apparent that the present invention provides an improved drier installation which is extremely simple and compact in construction, and which is moreover highly eiiicient in operation. The formation of the inner flights 28 of the revolving y drum, with air passages therethrough prolongs the life of the drier and also offers an opportunity for increased production. Due to the circulation of air through the flights 28, these flights do not become overheated and thus tend to eliminate scorching of material. The cooling of these flights also permits the use of higher inlet temperatures so that more material can be fed into the machine in order to absorb the additional heat.

The improved conveyor seal is relatively simple as compared to prior feeders for apparatus of this type, and has fewer moving parts which tend to wear rapidly. The sealing plates 6l, 55 function automatically to produce a uniform stream of entering material, and to prevent undesirable ingress of cold air to the drying zone.

The improved housing 23 provides an enclosure for both fans, for the driving motor, and for accessory apparatus such as oil pumps, compressors, and expansion tanks. This housing also encloses the auxiliary separator and cooler, and serves as a support for the main separator 24. The housing 23 with the apparatus confined therein may be readily handled as a unit and thereby facilitates assembly of the installation. The adjustable chute 'I6 which permits direct by-pass'ing of the treated product, is of considerable advantage in many instances, and the adjustable baille 80 permits variation in the velocity of flow of the material through the conduit 'l1 so as to insure most eillcient cooling and separation of abnormal particles.

The present improvement has proven highly advantageous in actual use, and it has been found that by providing detachable units such as earlier described, the installation can be readily assembled and dismantled in the shortest possible time. The drier drum l is preferably externally insulated so as to prevent undesirable loss of heat, and the furnace 2| should be likewise insulated. All mechanism of the installation is effectively protected against damage and from the weather, and the interior of the drying drum is also protected against deterioration due to overheating and is devoid of objectionable corners wherein material might accumulate.

With respect to subject matter illustrated and described but not claimed herein, reference is made to divisional application Serial No. 414,582 filed October 11, 1941.

It `should be understood that it is not desired to linut this invention to the exact details of construction or to the precise mode of use, herein shown and described, for various modifications within the scope of the claims may occur to persons skilled in the art.

We claim:

1. In a drier, a drum forming a drying zone, means for maintaining sub-atmospheric pressure in said zone, a casing having a lower inlet and an upper outlet, the latter of which communicates with said zone, an endless conveyor within said casing having movable flights for delivering a constant stream of material from said lower inlet `to said zone through said upper outlet, means for preventing uncontrolled admission of air with the material including swingable airseals coacting by gravity with the upwardly and downwardly movable stretches of said conveyor, said means being positioned to form a. closure between said conveyor and adjacent casing por tions, and an air port adjacent the upper end of said casing for admitting controlled quantities of cold air to said drying zone.

2. In a drier, a rotary drum having a drying zone therein, means for introducing heated gas to said zone, an endless conveyor having a casing and having constantly advancing fligh' for delivering a continuous stream of bulk material to the gases entering said zone, and means for preventing uncontrolled admission of air with the material including an automatically adjustable swingable shutoff plate having a portion extending longitudinally of the conveyor between the ends thereof to simultaneously span a plurality-of ights thereon and form a closure between said conveyor and the adjacent casing portions.

3. In a drier, a rotary drum having a drying zone therein, means for introducing heated gas to said zone, an endless conveyor having a casing and having constantly advancing flights for delivering a continuous stream of bulk material to the gases entering said zone, and means for preventing uncontrolled admission of air with the material including an automatically adjustable swingable shutoff plate having a portion extending longitudinally of the conveyor between the ends thereof and normally urged by gravity into contact With said conveyor to rest on a plurality of ights simultaneously and form a closure between said conveyor and adjacent casing portions.

4. In a drier, a drying drum having a drying zone therein, a conveyor casing having an inlet and an outlet, the latter of which communicates with said zone, an endless conveyor within said casing having movable flights for delivering a constant stream o'f material from said 'inlet through said outlet into said zone, said casing having an upper wall formed with an opening, and an air seal pivotally supported from said upper wall of the casing adjacent said opening and normally closing the latter, said air seal being swingable in a direction b'oth inwardly and outwardly of the casing and normally coacting with said moving flights to form a closure between said fiights and adjacent casing portions and thereby prevent admission of uncontrolled quantities of fresh air to the drying zone along the delivery stretch of the conveyor, and means for preventing admission of uncontrolled quantities of air between the bottom of the delivery stretch of the conveyor and the bottom wall of the casing.

5. In a drier, a drying drum having a drying zone therein, a conveyor casing having an inlet and an outlet, the latter of which communicates with said zone, an endless conveyor Within said casing having movable iiights for delivering a constant stream of material .from said inlet through said outlet into said zone, imperforate means positioned within the casing and extending between the delivery and return stretches of the conveyor normally urged against the return stretch of the conveyor to press the ights of the latter against the lower wall of the conveyor casing, and means for vpreventing admission of uncontrolled quantities of air above the delivery stretch of the conveyor.

6. In a drier, a drying drum having a drying zone therein, a conveyor casing having an inlet and an outlet the latter of which communicates with said zone, an endless conveyor within said casing having movable ights for delivering a constant stream of material from said inlet through said outlet into said zone, an air seal member pivotally supported for swinging movement withinthe casing and extending between the delivery and return stretches of the conveyor, said air seal member beingurged by gravity against the inner side of the return stretch of the conveyor to press the flights of the latter against the lower wall of the conveyor casing, and means for preventing admission of uncontrolled quantities of air above the delivery stretch of the conveyor.

'1. In a drier, a drying drum having a drying zone therein, a conveyor casing having an inlet and an outlet, the latter of which communicates with said zone, an endless conveyor Within said casing having movable ights for delivering a constant stream of material from said inlet through said outlet into said zone, an air seal member pivotally supported for swinging movement within the casing and extending between the delivery and return stretches of the conveyor,

`means including a pin and slot connection for guiding the free end of said air seal member in swinging movement and for limiting the extent of movement thereof, said air seal member being normally urged by gravity against the inner side of the return stretch of the conveyor to press the flights thereof against the lower wall of the conveyor casing, and means for preventing ad- 'said casing having mission of uncontrolled quantities of air above the delivery stretch of the conveyor.

8. In a drier, a drying drum having a drying zone therein, a conveyor casing having an inlet and an outlet, the lattervof which communi'- cates with said zone, an endless conveyor within a constant stream of material from said inlet through said outlet into said zone,van air seal member pivotally supported for swinging movement within the casing and extending between l the delivery and return stretches of the conveyor,

guide members having slots therein' which ex tend transversely of the direction of movement of the conveyor, means for adjusting the position of said guide members to vary the position respect to the= of the lower ends of the slots with lower stretch of the conveyor, pins on the free end of slots, said air seal gaged with the inner of the conveyor to member being movably enpress the flights thereof against the lower wall of the conveyor casing;

preventing admission of unconabove the delivery and means :for trolled quantities of air stretch of the conveyor.

9. In a drier, a drying drum having a drying zone therein, a conveyor casing having an inlet and an outlet, the latter of which communicates with said zone, an endless conveyor within said casing havingmovableflightsfor delivering a constant stream of material from said inlet through said outlet into said zone, imperforate means coacting with the delivery stretch of the conveyor and extending to the top wall of the casing to prevent uncontrolled admission of cold air with the material, and imperforatemeans positioned ,in the casing and extending between the delivery and return stretches of the conveyor normally engaging the inner side of the return stretch of the conveyor to press the conveyor flights against the lower wall of the conveyor casing.

HARLOW L. SCH'MlDT. HENRY C. FRENCH.

movable nights for deliveringv said air seal member cooperable with said'- side of the return stretch

Images