US2319674A - Rotary drier - Google Patents

Description

v May 18, 1943. H. c. FRENCH ET AL ROTARY DRIER OriginalFiled July 3, '1939 3 Sheets-Sheet 1 AT TORN-EYS.

HQ FRENCH ET AL ROTARY mum May is, 1943.

Original Filed July 5, 1939 E tj9.4.

- s Sheets-Sheet 2 ATTORNEY5.

13, 1943- v H. c. FRENCH 11m. I 2,319,674

noun DRIER Y I Original Filed July 3, I939 3 SheetsSheet 3 Patented May 18,

no'rsnrnnmn Henry C. French, Elm Grove, and Harlow L. Schmidt, Milwaukee, Wis., assignors to The Heil 00., Milwaukee. Wis., a corporation of Wisconsin Original application July 3, 1939, Serial No. 282,592. Divided and this application October 11, 1941, Serial No. 414,582

Claims. (c1. eta-'32) sion of application Serial No. 282,592, filed July Generally defined, an object of our-invention is to provide various improvements in the construction of rotary driers, whereby the cost of construction and operation thereof is reducedto a minimum while the efficiency-ls enhanced to a maximum.

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

To provide a drier 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 improved instrumentalities for protecting the various elements of a drying unit, against deterioration due to exposure to the weather and excessive heat. e

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 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 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 be had by referring to the drawings accompanying and forming a part of this specification wherein-like reference characters designate the same or similar parts in the various views.

Fig. i is a perspective viewof a rotary drier installation embodying the invention;

Fig. .2 is an enlarged transverse vertical sec tion through the material discharge and ian housing, showing the improved product purifier in action;

Fig. 3 is a fragmentary section similar to that 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 correspoinding 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 central vertical section through fragments of the drier drum, showing details of the air cooling system; and

Fig. 7 is a part sectional end view of the inlet end of the drum of Fig. 6, the section being taken along the line 7-4.

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.

I Referring to the drawings, the improved dryer installation illustrated therein comprises in general a horizontally elongated externally insulated rotary drying drum i5 having an inlet H5 at one end and an outlet ii at its opposite end,

the drum being provided with end tires 28 cooperable with rollers Hi to rotatably support the same; a feeder 20 and a furnace 2| associated with the inlet end of the drum i5 and cooperating with the drier inlet E6 to constantly introduce a mixture of raw material and heated gas into the drying zone 22; a dry material discharge housing 23 and a gas separator 24 associated with the discharge end of the drum i5 and having therein a main fan 25 cooperating with the outlet H to constantly withdraw the mixture of treated material and spent heating medium from within the drum i5; and mechanism including a motor 98 enclosed within the housing 23, for rotating the fans, revolving the drum i5, and actuating the feeder 20.

The improved rotary drying drum in which the circuitous drying passage or zone 22 is confined, has therein an inner central cylindrical shell 21 communicatingv withthe inlet i6 and provided with internal longitudinal hollow flights 28, and also has an intermediate shell 29 mounted therein between the nn 2i and the outer drum 8%, see Figs fi and '7. Theintermediate shell 29 and the drum iiare also provided with internal longitudinal flights 30, 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, l1, while the discharge end of the intermediate shell is spaced 5 from the inlet end head of the drier drum, thereby providing the circuitous passage. The partition 32 is provided with a cone "on one side thereof for deflecting the stream of mixed solids and gases from the inner shell 21 into the interl mediate shell 23, and has a cone 34 on its opposite side for deflecting the departing mixture through the outlet H. The overhanging ends of the shells 21, 23 are mounted for free expansion longitudinally of the drum l; and the hollow flights 23 within the shell 21 have their ends ad.- jacent 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 atmosan phere through ports 38. This construction of the flights 28 causes a constant circulation of relatively small quantities of cooling air therethrough during normal operation of the drier and protects these flights 28 against rapid deterioration due to exposure thereof to the hot gases entering the drying zone 22.

The endless conveyor type of 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 our co-pending application and communicates directly with the drier inlet l6.

The furnace 2| for supplying heated gases to the drying zone 22 through the inlet l8, may be either oil or gas fired, and is adapted to deliver the heating medium in swirling condition toward the inlet l6 and beneath the feeder delivery passage. The gravitating solids are thus spread and intimately mixed with the gaseous heating me- 4-0 dium, and the temperature of this mixture may be modified by admitting regulated quantities of tempering air in any desired manner. The furnace 2! may be readily detached from the drum l5 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 50 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 comprises three adjoining compartments G1, 38,

69 all forming part of the housing 23. The inner compartment 6'! provides an enclosure for the main suction fan 25, and has a side inlet communicating directly with the drum outlet l1, and also has a. tangential peripheral discharge passage 10 which is in open communication with the upper end of the cyclone separator 24. This separator 24 is of the well known type wherein the heavier particles are separated from the gases by centrifugal force created by swirling the mixture about a central upper gas outlet, and in which the separated heavy solids or particles gravitate toward alower outlet opening I 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. 4and5. The intermediate compartment 63 ofthe housing 23, has a downwardly directed fixed spout 15 therein which communicates directly with the separator outlet opening II, and below this spout I5 is located an adjustable by-pass chute l3 and a heavy particle separator and final cooling conduit 11, see Figs. 2 and 3. The chute I6 is rectangular in transverse cross-section and is slightly longitudinally tapered, and is moreover swingably adjustably suspended by a hinge 13 so that the chute will normally tend to assume a position as indicated in Fig. 2, in vertical alinement with the spout I5. 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 I8 is provided with a normally closed sight opening I9, and may be swung about its suspension hinge 13 into the position shown in Fig. 3 whereupon material passing through the chute 16 may be discharged at the front of the compartment 63 directly from the separator 24. The medial portion of the inclined separator and cooling conduit I1 is upwardly open and is normally disposed in direct vertical alinement with the open lower end of the chute I6, and an adjustable baflle plate 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 M 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 disposeddn open position as in Fig. 2 when the chute I6 is in vertical position. Above the medial upper opening in the inclined conduit 11, is a fixed downwardly extending baiille wall 83, and the upper end of this conduit 11 is curved laterally and extends into the outer compartment 69 axially of the shaft 12. J

The outer compartment 69 of the forms an enclosure for the auxiliary fan housing 84 within which the fan 13 is confined, and the axial inlet opening 85 of the fan 13 communicates directly with the separator conduit ll while the peripheral tangential outlet 86 thereof communicates with a final delivery pipe 81 which may lead to any desred 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 90 which-is operatively connected to the fan driving pulley "l4by 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 89 will produce simultaneous operation of the fans 25,13, drum I5, and feeder 20. The rear door 8,9-is exposed to both compartments 68,69, and is provided with a screen as shown in Fig. 2 for permitting passage of atmospheric air/tothefan 13. 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 15, for shipment, and the entire assemblage may there fore be conveniently handled in the form of segregated units for transportation, but may also be quickly assembled into a complete installation.

housing 23' v aaraova may be placed in operation and any material deposited within the feed conveyor hopper will naturally be carried upwardly and deposited into the conduit leading from the furnace 2i. During normal operation of the furnace 2i, hot gases of combustion mixed with heated air are being delivered with a swirling motion through the drier inlet l6, and the bulk material which is being fed in a constant stream by the feed conveyor 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 adjacent the drier outlet li. During its passage through the drier drum it, the solid particles of the mixture will be constantly showered across the interior of the shell 2'? by the revolving flights 2s, and the particles are ultimately drawn past the cone 33 into the intermediate shell 29 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 38 further shower the solid particles and agitate the mixture, and the finally treated material is ultimately discharged through the outlet ill along the cone it. The fan 25 then propels the mixture of solids and gas through the main separator 2 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. It is disposed as shown in Fig. 3, the dried material is Icy-passed to the exterior of the housing 23. If, however, the chute it is disposed as shown in Fig. 2, the dried material is drawn through the inclined conduit Ti and upwardly through the fan l3 where it is cooled and eventually delivered through the pipe ti. During passage of the solids into the conduit II, 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 ill. The lighter dried product passes upwardly past the bafile 8t and through the fan l3, and is thoroughly cooled during this passage.

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 emeient in operation. The formation of the inner flights 28 of the revolving drum, with air passages therethrough prolongs the life of the drier and also ofiers 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 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 22%. 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 it which permits direct bypassing of the treated product, is of considerable advantage in many instances, and'the adjustable bafiie 80 permits variation in the velocity of flow oi the material through the conduit Tl so as to insure most efficient 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 i5 is preferably externally insulated so as to prevent undesirable loss of heat, and the furnace 2i should be likewise insulated. All mechanism of the installation is efiectively 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.

It should be understood that it is not desired to limit 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 rotary drum having a central tubular drying zone open for the admission of material to be treated at one end and terminating axially of a deflecting cone at its opposite end, a series of elongated hollow material agitating flights extending along said zone and being sealed therefrom at the material admission end but being open adjacent said cone, conduit means connecting the sealed ends of said vanes with atmosphere, andmeans for reducing the pres-' sure in said zone below atmospheric.

2. In a drier, a rotary drum having an inlet opening at one end and having a drying zone therein, a series of material agitating flights extending longitudinally fromsaid inlet end of the drum toward the opposite end, each of said flights being hollow and having an opening communicating with the drying zone, there being an annular chamber adjacent the inlet opening of the drum communicating with the hollow interiors of all of the flights, means positioned circumferentially outwardly of the inlet openin of the drum for admitting fresh air to said annular chamber, and means for causing said fresh air to be drawn through said flights.

3. In a drier, a rotary drum having an inlet opening at one end and having a drying zone therein, means for admitting-hot gases of combustion to said inlet opening, a series of material agitating flights extending longitudinally from said inlet end of the drum toward the opposite end, each of said flights being hollow and having an opening communicating with the drying zone, means including a duct circumferentiallv outwardly of the inlet opening of the drum for connecting portions of said flights adjacent the inlet end of the drum with the atmosphere, and means for causing air to be drawn through said flights.

4. In a drier, a rotary drum having an inlet opening at one end and having a drying zone therein, means for admitting hot gases of combustion to said inlet opening, a series of material agitating flights extending longitudinally from said inlet end of the drum toward the opposite end, each of said flights being hollow and having an opening communication with the drying zone, an annular chamber surrounding the inlet opening of the drum and connecting portions of said flights adjacent the inlet end of the drum with the atmosphere, and means for causing air to be drawn into said flights.

5. In a drier, a rotary drum having an inlet opening at one end and having a drying zone therein, means for admitting hot gases of combustion to said inlet opening, a series of material agitating flights extending longitudinally from said inlet end of the drum toward the opposite end, each of said flights being hollow and having an opening communlcatingwith the drying zone, means including a duct circumferentially outwardly at the inlet opening of the drum for connecting portions of said flights adjacent the inlet end of the drum with the atmosphere, means for causing air to be drawn through said flights, and means adjacent the inlet opening of the drum for sealing the hollow interiors of the flights from the hot gases of combustion admitted through said inlet opening.

6. In a drier, a rotary drum including spaced inner and outer cylinders, said inner cylinder having an inlet opening at one end and having a drying zone therein, means for admitting hot gases of combustion to said inlet opening, a series of material agitating flights extending longitudinally from said inlet end of the inner cylinder toward the opposite end, each of said flights being hollow and having an opening communicating with the drying zone, means forming an annular chamber surrounding the inner cylinder adjacent the inlet end thereof, means for admitting fresh air to said annular chamber, there being perforations in the wall of the inner cylinder affording communication between said annular chamber and the hollow interiors of the flights, and means for causing. air to be drawn into said annular chamber and through the flights.

7. In a drier, a rotary drum having a material inlet opening at one end, -means adjacent said end for supplying heated gases to the drier, a series of material agitating flights extending longitudinally from said inlet end of the drum toward the opposite end, said flights being hollow and having outlet openings inside of the drum spaced toward the opposite end 'of the drum from the place of admission of heated gases to the drum, means for connecting portions of said flights adjacent the inlet end of the drum with the atmosphere, and means for causing air to travel through said flights and be discharged into the drum to act on the material after the material has first been acted upon by the hot gases.

8. In a drier, a rotary drum having a material inlet opening, means for supplying heated gases to the drier, a series of material agitating flights extending longitudinally within the drum, said flights being hollow and having outlet openings inside of the drum, means for connecting portions of said flights with the atmosphere, and means for causing air to travel through said flights and be discharged into the drum, the outlet openings of the flights being so positioned with respect to the place of admission of the hot gases to the drum that air is discharged from the flights into the drum after the material to be dried has first been acted upon by the hot gases.

9. In a drier, a rotary drum having a material inlet opening at one end, means adjacent said end for supplying heated gases to the drier, a series of material agitating flights extending longitudinally from said inlet end of the drum toward the opposite end, said flights being hollow and having outlet openings inside of the drum spaced toward the opposite end of the drum from the place of admission of heated gases to the drum, means for connecting portions of said flights adjacent'the inlet end of the drum with the atmosphere, and a suction fan for causing the material to be dried to travel through the drum, said same means also causing air to travel through said flights.

10. In a drier, a plurality of spaced and communicating concentric drums rotatable together, the innermost drum having an inlet opening at one end and having its opposite end in communication with the next adjacent drum, means adjacent the inlet end of the inner drum for supplying heated gases to the drier, a series of material agitating flights extending longitudinally from the inlet end of the innermost drum toward the opposite end, said flights being hollow and having outlet openings inside of the drum spaced toward the opposite end of the drum from the place of admission of heated gases to the drum and near the place .of communication between the innermost drum and the next adjacent drum, means for connecting portions of said flights with the atmosphere, and means for causing air to travel through said flights and be discharged into the drum to act on the material when the material is about to enter the next adjacent drum.

HENRY C. FRENCH. HARLOW L. SCHMIDT.

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