ROTARY DRYER HAVING NOTCHED FLIGHTS

Abstract

A dryer adapted for use in an asphalt plant. The dryer includes a drum having an inner wall and a flight having a proximal end connecting the flight to the inner wall of the drum and a distal end that is spaced apart from the proximal end. A first profile extends from the proximal end to the distal end of the flight and defines a flight shape. A notch is formed in the distal end of the flight, which notch includes a notch shape that is defined by a second profile. The second profile has a length L, a center point, and a portion that substantially approximates a conic section.

Claims

1. A dryer adapted for use in an asphalt plant, the dryer comprising: a drum having an inner wall; a flight having a proximal end connecting the flight to the inner wall of the drum and a distal end that is spaced apart from the proximal end; a first profile extending from the proximal end to the distal end that defines a flight shape of the flight; a notch formed in the distal end of the flight having a notch shape that approximates a conic section and that is defined by a second profile, the second profile having a length L, a notch center, and formed by a pair of notch profile portions with ends joined together at the notch center and opposite ends joined to the distal end of the flight, each notch profile portion comprising a spline of at least two sections connected together at ends and that are each defined by a different polynomial function and have a different curvature.

2. (canceled)

3. The dryer of claim 1 wherein the first profile comprises a partial conic section formed by a spline of at least two sections connected together at end and including at least two sections that have a different curvature.

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. The dryer of claim 1 wherein at least a portion of the first profile is curved.

10. (canceled)

11. A dryer adapted for use in an asphalt plant, the dryer comprising: a drum having an inner wall; a flight having a proximal end connecting the flight to the inner wall of the drum and a distal end that is spaced apart from the proximal end; a first profile extending from the proximal end to the distal end that defines a flight shape of the flight and that is formed by a spline that includes at least three sections that each have a different curvature; and a notch formed in the distal end of the flight having a notch shape that is defined by a second profile, the second profile having a length with a notch center.

12. The dryer of claim 11 wherein the spline includes at least two curved sections joined together at ends thereof that have a different curvature and are each defined by different second-degree polynomial functions.

13. The dryer of claim 11 wherein at least one of the three sections comprises a curved and partial conic section and wherein the flight shape, as a whole, is continuously curved and comprises at least a partial conic section.

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. A dryer apparatus comprising: a flight configured for use in a dryer in an asphalt plant and having a proximal end configured to mount to an inner surface of a drum of the dryer and a distal end, wherein a shape of the flight is continuous and curved; and a notch disposed in the distal end of the flight, the notch having a notch center and being defined by a continuous curve that approximates a conic section and that is formed by a pair of notch profile portions with ends joined together at the notch center and opposite ends joined to the distal end of the flight, each notch profile portion comprising a spline of at least two sections connected together at ends and that each have a different curvature.

19. (canceled)

20. (canceled)

21. The dryer of claim 1 wherein the at least two sections of each notch profile portion comprise a straight section and a curved section.

22. The dryer of claim 1 wherein each notch profile portion comprises a spline of at least three sections that are each defined by a different polynomial function to provide a different curvature.

23. The dryer of claim 1 wherein the spline of each notch profile portion includes two or more conic sections that are each selected from the group consisting of a hyperbola and a parabola.

24. The dryer of claim 23 wherein each notch profile portion further includes at least one straight section.

25. The dryer apparatus of claim 18 wherein the spline includes at least one curved section and one straight section.

26. The dryer apparatus of claim 18 wherein the spline is continuously curved without bends.

27. A dryer flight configured for placement within a drum of a dryer and configured to scoop, carrying, and shower asphalt material within the drum as the drum is rotated, the dryer flight comprising: a proximal end configured to connect the flight to an inner wall of the drum; a distal end that is spaced apart from the proximal end; and a flight shape beginning at the proximal end and ending at the distal end of the flight that is defined by a spline having three or more sections joined together at ends, wherein the three or more sections include at least two of the following types of sections that are each defined by a polynomial function: a straight section, a parabolic section, or a hyperbolic section, wherein the end of the section is located where the type of section changes from one type of section to another type of section or where the polynomial function and curvature of the section changes to a different polynomial function and different curvature.

28. The dryer flight of claim 27 further comprising a notch formed in the distal end of the flight having a notch shape defined by a pair of notch portions joined together at a notch center of the notch and extending to the distal end of the flight, a shape of each notch portion defined by a spline having three or more sections joined together at ends, wherein the three or more sections include at least two of the following types of sections that are each defined by a polynomial function: a straight section, a parabolic section, or a hyperbolic section, wherein the end of the section is located where the type of section changes from one type of section to another type of section or where the polynomial function and curvature of the section changes to a different polynomial function and curvature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The presently preferred embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout, and in which:

[0019] FIG. 1 is a partial sectional front view depicting a conventional dryer drum;

[0020] FIG. 2 is a cross-sectional view of a conventional dryer drum equipped with flights;

[0021] FIG. 3 is a front elevation view of a conventional flight;

[0022] FIG. 4 is a top plan view of the flight of FIG. 3;

[0023] FIG. 5 is a right-side elevation view of the flight of FIG. 3;

[0024] FIG. 6 depicts a cone and conic sections that are created by intersecting the cone with a plane;

[0025] FIG. 7 depicts the conic sections of FIG. 6 from an overhead perspective along the Y-axis;

[0026] FIG. 8 is a perspective view of a flight having an overall parabolic shape and a parabolic-shaped notch formed therein according to an embodiment of the present invention;

[0027] FIG. 9 is a front elevation view of the flight of FIG. 9;

[0028] FIG. 10 is a top plan view of the flight of FIG. 9;

[0029] FIG. 11 is a right-side elevation view of the flight of FIG. 9;

[0030] FIG. 12 is a front elevation view of the flight of FIG. 9 shown in a flattened condition illustrating the parabolic-shaped notch; and

[0031] FIG. 13 is a front elevation view depicting notch profiles that incorporate portions of a conic section shape according to three alternative embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0032] This description of the preferred embodiments of the invention is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. The drawings are not necessarily to scale, and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness.

[0033] With reference now to FIGS. 6 and 7, a cone 100 is illustrated. This particular cone 100 is a single three-dimensional geometric shape (i.e., not a double cone) that tapers upwards from a flat base 102 (i.e., not an infinitely extended cone) to an apex 104. In general, a cone may be constructed by revolving a triangle about an axis extending through one of its sides. In this particular case, the cone 100 is formed by a right triangle having an x-leg 106 extending along a horizontal x-axis and ending at a point 108, a y-leg 110 extending along a vertical y-axis that is perpendicular to the x-axis and ending at a point 112, and a hypotenuse 114 extending between point 108 and point 112. Revolving that triangle about the y-axis forms cone 100, including the flat base 102, the apex 104, and the wall 116 extending between the base and the apex. Various conic sections may formed by intersecting a cone with a planar surface. The shape that is formed depends on the angle of intersection. In the illustrated embodiment, that angle of intersection is measured from the flat bottom 104 of the cone 100 to the plane intersecting the cone. When angle is 0, a circular shape 118 is formed. As angle increases, other conic sections are formed, including an ellipse 120, a parabola 122, and a hyperbola 124. Eventually, if angle were increased to 90, a V or triangle shape is formed.

[0034] With reference now to FIGS. 8-11, there is provided a flight 200 suited for use in a dryer used in an asphalt plant according to an embodiment of the present invention. Preferably, when in use, a plurality of substantially identical flights 200 would be connected to an inner wall 16 (FIG. 2) of a drum 10 and arranged substantially parallel to each other. Although, in other embodiments, other arrangements other than a substantially parallel arrangement may be used.

[0035] Flight 200 has a proximal end 202 that connects the flight to an inner wall of the drum of a rotary dryer and a distal end 204 that is spaced apart from the proximal end. A first profile 206 extends through the flight 200, from the proximal end 202 to the distal end 204, and defines the shape or profile of the flight (when viewed from one side, as in FIG. 11). In certain embodiments, the first profile 206 includes a portion that substantially approximates a portion of a conic section. The term substantially approximates, when used to describe a conic section, or a portion of a conic section, indicates a spline that approximates a conic section or a portion thereof, as well as a continuous curve comprising a conic section or a portion thereof.

[0036] In the illustrated embodiment, first profile 206 includes at least one curved portion and comprises a partial substantially parabolic overall shape (when viewed from one side, as in FIG. 11) of the flight 200. In some cases, the first profile 206 may comprise a single, continuously curved line. However, in this particular case, first profile 206 is a spline that is comprised of two or more line sections, including at least one curved section, that are joined together at ends. The shape of these sections may be defined by polynomial functions, including first-degree polynomials (i.e., straight lines) and second-degree polynomials (i.e., curved lines). In this particular case, first profile 206 includes several straight or curved sections of varying lengths between the proximal end 202 and the distal end 204 to define the substantially parabolic shape.

[0037] A notch 208 is formed in the flight 200 and has a length L with a center point 210. The shape of the notch 208 is defined by a second profile 212 that extends through the flight along the length L of the notch. In certain preferred embodiments, a portion of the second profile 212 at least substantially approximates a conic section or a portion thereof. The conic section of the second profile 212 may be located at any position along the length L of the notch 208. In a preferred embodiment, the conic section of the second profile 212 is disposed at approximately the center point 210 of the notch 208. However, as discussed above, a V-shaped notch tends to produce a relatively thin veil of aggregate material on the uphill side of the drum and a comparatively thicker veil of aggregate material on downhill side of the drum. For that reason, as the term is used herein, conic section specifically excludes the V-shape formed when angle of intersection (FIG. 6) is equal to 90. Therefore, conic section refers only to those shapes (or portions thereof) formed when angle of intersection is less than 90, including a portion of a circle, ellipse, parabola or hyperbola.

[0038] Referring now to FIG. 12, flight 200 has a flight depth D1, measured along a surface of the flight, between the proximal end 202 and the distal end 204. Additionally, flight 200 has a notch depth D2 that is measured along the surface of the flight from the distal end 204. In the preferred embodiment illustrated in the drawings, notch depth D2 varies along the length L of the second profile 212. In some embodiments, notch depth D2 is greatest at a center point of the second profile. In certain cases, the maximum notch depth D2 is approximately 20% to approximately 80% of the flight depth D1. In other cases, the maximum notch depth D2 is approximately 30% to approximately 60% of the flight depth. In still further cases, the maximum notch depth D2 is approximately 50% of the flight depth D1.

[0039] With reference to FIG. 13, a portion of three flights 200A, 200B, 200C with alternative notch designs, determined by second profiles 212A, 212B, 212C, is illustrated. As detailed below, second profiles, like first profiles, may be splines. Second profile 212A includes a conic section portion 214 centered approximately at center point 210 that is hyperbolic in shape, which indicates a steep angle . Second profile 212B includes a conic section portion 216 that is centered approximately at center point 210B. Conic section portion 216 is more parabolic in shape than the conic section portion of second profile 212A, which indicates a more moderate angle . Second profile 212B also includes a straight portion 218 that is adjacent conic section portion 216 and another hyperbolic conic section portion 220 located adjacent the straight portion. Lastly, second profile 212C includes a conic section portion 222 that is centered approximately at center point 210C, which indicates an even more moderate angle . Conic section portion 222 is more circular than either of the conic section portions of second profile 212A or second profile 212B. A pair of adjacent straight sections 224, 226 are located adjacent conic section portion 222 to define second profile 212C. From the above discussion, it may be appreciated that by designing second profiles as splines, the resulting notches for flights may be highly customizable to meet process requirements and to optimize performance of the dryer.

[0040] Although this description contains many specifics, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments thereof, as well as the best mode contemplated by the inventor of carrying out the invention. The invention, as described and claimed herein, is susceptible to various modifications and adaptations as would be appreciated by those having ordinary skill in the art to which the invention relates.