US 3565168 A
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United States Patent Inventors Harold R. Powell  References Cited King ofPrussia; UNITED STATES PATENTS F g- 2'2" warn" Haas 442,011 12/1890 Bulckens 165/108 1 N gi'g 1,622,921 3/1927 Offenhauser l65/90X PP v 969 2,628,080 2/1953 Mack 165/156X Filed 2,926,002 2/1960 Spielvogel l65/109X Patented Feb. 23, 1971 FOREIGN PATENTS Assignee Penuwalt Corporation 46,646 5/1889 Germany 165/90 Primary Examiner-Albert W. Davis, Jr. CONE DRYER Attorneys-Stanley Bilker and Carl A. Hechmer 4 Claims, 3 Drawing Figs. US. Cl. 165/88; ABSTRACT: A cone dryer having an extended surface heat 34/108,34/132; 165/90,165/169;259/57, 259/81 transfer platen in the form of an annular cylindrical jacket Int. Cl ..F26b 11/04, suspended in concentrically spaced disposition from the inner F28d 11/08 walls of the dryer. The increased heat transfer area supple- Field of Search 165/88, 86, ments the original dryer contact surface while the cylindrical 90; 259/81, 82,85, 57, 58, 48; 34/133; 34/132, annulus impedes the fall of product material so as to provide 134, 108; 165/169, 89 superior blending action and quicker drying times.
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PATENTEDf EB-2 MI 3565; 168
sum 2 BF '2 Has ' INVENTORS. HAROLD R. POWELL DAN/EL I? SWEENEY WARNER CZHAAS A TOR/VE Y CONE DRYER This invention relates to cone dryers and more particularly relates to a means for extending the heat transfer surface of cone dryers so as to provide improved blending action for the product and quicker drying time.
The conventional conical dryer comprises a jacket shell having a central cylindrical portion from which outwardly directed conical portions extend. The shell is horizontally mounted on trunnions for rotations trarisverse to the longitudinal axis of symmetry of the cylinder and the cones. A heating medium, such as hot oil, is pumped into the jacket through one trunnion while a vacuum may be applied to the interior of the dryer through the other trunnion. Although the sloping walls of the cones permit more rapid emptying of solids when the dryer is in stationery position, the heat transfer area of conventional cone dryers is necessarily limited by the dryer configuration.
Since rotating drum or cone dryers are basically for batch operation, it is apparent that the residentdrying time is a function of surface heating area which is a limiting factor in all vacuum drying systems. However, because cone'dryers are usually loaded to about-65 percent of their capacity, to incorporate ill-considered heat transfer surface area inside the dryer would not only decrease the amount of the grandular material to be dried but also would interfere with the orderly blending actionof such granulated material.
It is therefore an object of this invention to incorporate additional heat transfer area fora given dryer configuration without impeding blending and mixing action or appreciably diminishing the. dryer capacity.
Another object of this invention is to supplement the. contact surface of a cone dryer so as to provide more efficient and quicker drying times. a
Still another object of this invention is to develop a design for incorporating supplemental heating surface in a cone dryer which will offer minimum resistance to product flow.
Yet another object of this invention is to provide a configuration for auxiliary heat transfer surface which will improve the blending and mixing action of cone dry'ers.
Other objects of this invention are to provide an improved device of the character described which is easily and economically produced, which is sturdy in construction and both highly efficient and effective in operation.
With the above and related objects in view, this invention consists of the details of construction and combination of parts as will be more fully understood from the following detailed description when read in conjunction with the accompanying drawings in which:
H6. 1 is a front elevational view, and partly broken away of a'cone dryer embodying this invention;
H6. 2 is a sectional view taken along lines 22 of FIG. 1; and
FIG. 3 is a perspective view, and partly broken away, of an extended surface heat transfer member embodied in this invention.
Returning now in greater detail to the drawings in which similar reference characters refer to similar parts, we show a cone dryer, generally designated as A, in which is incorporated an extended surface heat transfer baffle, generally designated as B. j
The cone dryer A comprises a shell 12, a pair of hollow trunnions l4 and 16 and a drive mechanism 18 for effecting rotation of the shell. The shell 12 includes a pair of truncated cone portions 20 and 22 outwardly projecting from a medial cylindrical portion 24. Each end of the shell is open to provide an inlet hatch 26 and a discharge 28. An inner shell 30 is generally coextensive with the exterior shell 12 and defines a jacket through which steam or hot oil may circulate.
The drive unit 18 constitutes a suitable chain and sprocket system or gear drive which is connected to a suitable motor (not shown). A pulley or sprocket 32 is keyed to the trunnion 16 which is journaled in bearing block 34. Trunnion 14 is similarly journaled in a bearing block 36 at the dead end.
Hot oil enters an inlet 38 in a rotary joint 40, for example, a Johnson joint, and passes through an inner pipe 42 which is concentrically disposed within trunnion 16. Oil is discharged from the rotary joint 40 through exit 44 after it has passed from the jacket 30 through the annular space 46 between the trunnion 16 and the inner pipe 42. The trunnion 16 is affixed to the cylindrical wall 24 by means of a sealed end cap 48, the trunnion 16, the shell 12 and the inner pipe 42 all rotating together as a unit. The: inner pipe 42 is held in coaxially spaced disposition within the trunnion 16 by means of a sleeve 50 welded to the inner, wall of the jacket 30 at one end and a collar 52 connected to the trunnion 16 at the drive end.
The interior of the cone dryer shell 30 maybe evacuated through conduit 54"which extends to the approximate center of the dryer unit: A filter screen 56 prevents particles of the material being dried from passing into the vacuum system. The conduit 54 extends through the trunnion l4 and is coupled at the distal end to a suitable vacuum pump. The trunnion 14 is secured to the cylindrical portion 24 by a flange 58 so that the trunnion l4 and the flange 58. rotate about the conduit 54 on sealed bearing 60. A thermocouple 59 and a nitrogen feed tube 61 extend into the center of the dryer A through the conduit 54.
' The extended surface heat transfermember B constitutes a closed annulus which is dylindrical in configuration and define a tortuous path for the heating medium. The annulus is described by concentrically spaced inner and outer cylindrical shells 62 and 64 whose ends are closed by rims or flanges 66 and 68. The tortuous path is formed by a series 'of circumferentially arranged baffles 70, 72, 74 and 76 and a longitudinally extending strut 78, as best shown in FIG. 3. Oil from the inlet pipe 42 enters the central channel from a pipe coil and proceeds in a circumferential path between baffles 72 and 74. The single path divides into a pair of channels after arrival at the strut 78. Thereafter one channel proceeds between baffles 70 and 72 circumferentially back to the strut 78 and discharges between baffle 70 and flange 66 through exit pipe coil 82. The other channel follows between baffles 74 and 76 then diverges at the strut 78 into a discharge channel defined by end flange 68 and baffle 76. Exit pipe coil 84 then carries the oil from the lower portion of the heat transfer member B to the jacket in the lower cone 22 while pipe coil 82 delivers the oil from the upper portion of the extended surface annulus B to the jacket in upper cone 20.
The annulus B is concentrically disposed within the cylindrical portion 24 of the dryer A and held in spaced disposition therein by a plurality of ribs 86. The ribs 86 are welded to the inner cylindrical shell of jacket 30 and also to the outer shell 64 of the annulus B. Each of the ribs 86 is gull winged in crosssectional configuration to accommodate for thermal expansion. The annulus B is also firmly supported by four circumferentially spaced posts which are affixed to the interior of the conical portion 22. The posts 90 thus provide subjaccnt support for the annulus when the dryer is in the position illustrated in FIG. 1. When the cone dryer A is inverted, the posts then act as a suspension.
Returning now to FIG. 4, oil which is delivered from the upper portion of the annulus B passes through pipe coil 82 into the jacket 30 in theconical portion 20. An internal channel directs the heating fluid in the jacket 30 to the apex of the cone portion 20 from which it then moves circumferentially in a labyrinth path back to the trunnion manifold 100. Similarly, oil emptied from the pipe coil 84 moves through a channel in the conical portion 22 out to the apex thereof from which it is then conducted in a similar circumferential tortuous path back to the central manifold 100. Thereafter, the heat transfer fluid returns to the rotary joint 40 via the annular space 46 from which it is discharged through exit port 44.
As is apparent from the foregoing description, the heating fluid is channeled through the entire jacket labyrinth of both the annulus B and thecone dryer A so as to avoid stagnant areas. Uniform heat transfer to the product being dried is thereby assured. ln addition, the ribs 86 act as radiating fins for heating the product falling through the space between the extended surface heat transfer annulus B and the main jacket 30 during rotation of the cone dryer A. The direction of mounting the annulus B otTers minimum resistance to product flow while maintaining maximum contact with the heat transfer area. In this regard, the product which is contained in the space between the extended heat transfer annulus B and the interior of the cone dryer A is retained for a longer period of time during rotation of the dryer than the product in the center. Thus, the cone dryer is usually loaded with product from between 60 percent to 65 percent of its volume and the material in the center is caused to follow a generally circular to elliptical path during rotation. However, the product in the rib area 86 is temporarily trapped until the forward portion of the annulus slopes downwardly. Accordingly, the retarded fall of the circumferentially disposed product affords a through mixing action such that peripheral material drops on top of the material at the center so as to achieve maximum blending action.
1. A cone dryer comprising an external shell having a medial cylindrical portion and outwardly diverging conical portions including a jacket defined by coaxially disposed inner and outer walls, a hollow substantially cylindrical annulus supported within said external shell and concentrically spaced from the inner wall of the medial cylindrical portion. a plurality of circumferentially spaced, longitudinally extending heatconductive ribs radially disposed between the outer surface of said cylindrical annulus and the inner wall of the medial cylindrical portion, means for rotating said external shell, said heatconductive ribs extending along at least a substantial portion of the length of said annulus, and means for circulating a heating medium through said annulus and said jacket whereby said annulus and said ribs extend the heat transfer contact surface for material being dried and at the same time impede the fall of product material therebetween to provide superior blending action and quicker drying time.
2. The cone dryer of claim 1 wherein the hollow interior of the annulus is battled to define a tortuous passageway therein, the passageway being divided into channels which diverge toward the ends of the cylindrical annulus.
3. The cone dryer of claim 2 wherein said jacket includes a series of circumferential conduits which converge from the apices of the conical portions toward the cylindrical portion.
4. The cone dryer of claim 1 wherein said ribs are of gull winged configuration in cross section.