US 3852892 A
Disclosed is a dryer for comminuted or powdered material, such as grain particles, having an outer drum and an interior element through which a heating medium such as steam is circulated, the drum and the interior element being concentric and rotated independently of each other. The drum rotates on a vertically tilted longitudinal axis so that material to be dried moves by gravity through the rotating drum which has vanes or lifts for raising the material to fall through the heated interior element. The assembly is characterized by use of seals through which air is drawn into the drum and air intake openings at both ends of the drum.
Description (OCR text may contain errors)
ied tats Sheehan atent 1 [4 1 Dec. 10, 1974 1 ROTARY DRUM DRYER  inventor: Daniel]; Sheehan, PO. Box 430,
Danville, 111. 61832 22 Filed: May 6, 1974  App]. No.: 466,958
I  US. Cl 34/134, 34/138, 34/242, 165/88, 165/92  Int. Cl. F26b 11/02  Field of Search 34/138, 134, 142, 135, 34/137, 128, 130, 242; 165/88, 92
'  References Cited v UNITED STATES PATENTS I 548,651 10/1895 Lamb 34/138 1,573,144 2/1926 Credo 34/17 1,928,004 9/1933 Bullerjahn.... 34/129 2,095,086 10/1937 Slemmer 34/135 Primary E.\'aminer-Kenneth W. Sprague Assistant Examiner-Larry l. Schwartz Attorney, Agent, or FirmWoodard, Weikart, Emhardt & Naughton  ABSTRACT Disclosed is a dryer for comminuted or powdered material, such as grain particles, having an outer drum and an interior element through whicha heating medium such as steam is circulated, the drum and the interior element being concentric and rotated indepen dently of each other. The drum rotates on a vertically tilted longitudinal axis so that material to be dried moves by gravity through the rotating drum which has.
vanes or lifts for raising the material to fall through the heated interior element. The assembly is characterized by use of seals through which air is drawninto the drum and air intake openings at both ends of the drum.
3 Claims, 6 Drawing Figures SHE DEC
PATENIEI] 0E0 10 m4 SHEEI 30F 4 Fig. 4
ROTARY DRUM DRYER BACKGROUND OF THE INVENTION Dryers of the counter rotating type are not unknown in the prior and an example of prior art structures is disclosed in Bullerjahn U.S. Pat. No. 1,928,004. The structure of the present invention distinguishes over the prior art in that, among other things, it utilizes adjustableair intake registers at both ends of the drum, one being adjacent to the subatmospheric air outlet duct from the drum and acting as a partial by-pass for incoming air thus controlling the air intake from the register .at the opposite end of the drum and the pressure drop across the seals. By permitting air to be drawn through the structural seals, leakage is always inward and the area around the exterior of the dryer installation is kept free of dust and particles passing through the dryer. The air moving inwardly through the seals may be sufficient to provide the desired air flow through the dryer, however, the presence of the intake registers permits more flexible control of this air flow component of the drying operation.-
I BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring initially to FIG. 1, the assembly of the present invention includes a stainless steel drum having a clean out door 11. Thedrum I0 is essentially an open ended cylinder with one end closed by the housing 12 and the other end closed by the stationary plate 13. A material inlet tube 14 communicates with an aperture assembly shown generally along the in the plate 13 and provides for entry of finally divided or granulated material, such as grain to be dryed into the drum. The housing 12 at the opposite end of the drum is provided with a material discharge fitting 16 at its base and atits upper portion, an air discharge duct 17 extends tangentially'sidewardly, the duct 17 being more clearly visible in FIG. 5.
The drum is rotated about its longitudinal axis by means of a chain 18 which extends around the drum and is driven by a drive member 19 rotated by the electric motor 21. The drum is supported for rotation on trunnion rings 22 whichrest upon trunnion rollers 23 and thrust rollers 24 (FIG. 4).- The rollers and the shaft extending through the drum are supported by a support frame 20.
The longitudinal axis of the drum is tilted downwardly slightly, that is, its left-hand end, as viewed in FIG. 1,.is slightly lower than its right-hand end so that materialintroduced through the inlet 14 will move, by
, gravity, through the length of 'the drum to be discharged through the discharge fitting 16. Extending axially through the drum is a central shaft 31 supported on bearings 32 and 33. As may best be seen in FIG. 3, a conventional rotary steam union fitting, indicated generally at 34 is attached to the shaft 31 and permits introduction of steam through interior passages in the shaft to a steam head, indicated generally at 36 in FIG. 3, whose purpose will be subsequently more fully described.
Referring'now primarily to FIG. 3 and 3A, an inwardly extending end portion 37 on the drum is pro vided with a marginal offset flange and the stationary plate 13 is provided with an adjacent, parallel, annular flange 13a and, as indicated by the air flow arrows in FIG. 3A, when the pressure within the drum is below atmospheric, air will move through the restricted space between the annular flanges 37a and 13a into the drum.
The housing 12, as may best be seen in FIG. 3, at its rightward margin forms the air discharge passage 17 and the material discharge passage 16. Within thev ported on the shaft 31. The shaft and the heating element 36 rotate independently ofthe drum 10, the drive for the rotation of shaft 31 being provided by the electric motor 41 (FIG. 1) which, through the drive member 42 chained to the sprocket 43, rotates the shaft and, hence, the heating element.
Referring primarily, again, to FIG. 3 it will be evident that the heating element includes a steam chest or header 46 through which steam from the fitting 34 circulates through tubes 47. The tubes 47 extend through a drain chamber 48 and through larger diameter tubes 49. The tubes 49 extend into apertures in a tube support plate 51 and are capped adjacent the plate. The
smaller diameter tubes 47 terminate short of the capped ends of the tubes 49 permitting steam to circulate back into the drain chest 48, as is conventional in the art. As will be evident from FIG. 4, the plate 51, near its center, is provided with multiple, relatively large area openings 52 which permit entry of material moving through the inlet duct 14 into the interior of the drum. Extending radially inwardly from the interior of the drum are a series of spaced lifter blades 53 which function to'raise the grain within the drum as the drum rotates depositing it onto the moving steam-heated tubes 49 of the heating element. Since the tubes of the heating element and the drum are rotated at different speeds, as is conventional, the grain or other finally divided material within the drum is repeatedly dropped 7 over the heated tubes, the temperature of the grain I amount of air drawn through the various annular flange seals. As may best be seen in FIG. 2 the stationary plate 13 is also provided with grill covered openings 61 and 62, whose effective area may be adjustable, which permits entry of air through the plate into the drum at its end remote from the material and air discharge openings 16 and 17.
In operation, with the tubes 49 heated by steam circulating therethrough, and with the heating element 36 and the exterior drum 10 rotating at the desired speeds,
- finally divided material may be'introduced through the duct 14. Finally divided material will be turbulently lifted and dropped through the moving, heated tubes 49 and contact with the heated surface of the tubes will transfer heat, by conduction, to the finally divided material. The interior of the drum 10 is at sub-atmospheric pressure brought about by operation of the exhaust fan 70, in discharge duct 72, driven by the fan motor 71 (FIG. 5). The discharge duct 72 communicates with the discharge passage 17, and upon operation of the fan air will be drawn through the annular restricted space between the flanges 37a and 13a and a and 12b. This air drawn through the restricted space between the flanges is heated and expanded by contact with the heating element 36 and flows through the drum and out the discharge duct 17. in its passage through the drum the air takes up the moisture evaporated from the material moving through the drum and exits with its acquired moisture through the discharge duct 17. The material, releived of its moisture after passage along thelength of the drum, exits through the discharge duct 16. Material may .be added'and withdrawn from the drum on a continuous basis.
The provision for-the intake of air into the drum through the flange seals functions to retain the material being dryed inside the drum and inhibits any fine dust in the material in the drum from flushing out to the exterior of the dryer. The rotating and sifting action provided by the lifter blades 53 serves to blend the material passing through the drum. The drum and the interior heating element may be rotated in the same direction at differing speeds or in opposite directions depending upon requirements. As previously mentioned, the adjacent flanges will normally provide sufficient air induction area for normal operating conditions, however, where necessary, the inlet registers or grills 12c, 61 and 62 may be opened to increase the air inlet area.
1. A rotary drum type dryer for grannular material comprising: a rotatably mounted drum and an interior heating element mounted for independent concentric rotation within the drum, means for independently rotating said drum and said heating element, a stationary plate at one end of said drum having a material inlet tube extending therethrough and into the drum interior, annular adjacent flanges on said drum and said plate defining an annular restricted air intake passage from the exterior to the interior of the drum, a stationary housing at the other end of said drum into which said drum extends, adjacent annular flanges on said drum and said stationary housing defining a further annular restricted air intake passage to the interior of said drum and housing, a material discharge opening at the base of said housing and an air discharge opening at the upper end of the housing,'and air moving means for drawing air from said' drum through said air discharge opening.
2. A rotary drum type dryer as claimed in claim 1 in which auxiliary air inlet passages are provided in said housing adjacent said air discharge opening and in said stationary plate for admitting air into said drum and housing other'than through the space between said adjacent annular flanges.
3. A rotary drum type dryer as claimed in claim 2 in which the effective size of said auxiliary air, inlet passages in said housing are adjustable.