Patent Publication Number: US-8109009-B1

Title: Air seal for rotary dryer/kiln

Description:
This application claims the benefit of U.S. Provisional Application No. 61/133,866, filed Jul. 3, 2008, which is hereby incorporated by reference in its entirety. 
    
    
     SUMMARY OF THE INVENTION 
     The invention provides a unique rotary dryer, rotary kiln air seal to prevent fugitive air from entering a kiln or dryer at the feed and discharge breechings. The new seal is a steel contact seal comprised of formed radiused sections which ride on a wear plate affixed on the rotating drum. The seal utilizes a single floating labyrinth resistance, allowing for radial expansion of the drum and uneven drum surface contact. The seal sections are spring loaded with bent stainless steel spring clips. The seal is so designed as to accept maximum drum longitudinal expansion as well. 
     The seals may be used as kiln seals, kiln breeching seals, kiln air seals, kiln or dryer leaf seals, kiln carbon block seals, high temperature radial kiln seals, vacuum kiln seals or pressure kiln seals. 
     These and further and other features of the invention are apparent in the disclosure, which includes the above and ongoing written specification, with the claims and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the oven primary seal assembly. 
         FIG. 2  is a front elevation of the seal assembly shown in  FIG. 1 . 
         FIG. 3  is a side elevation of the seal assembly shown in  FIGS. 1 and 2 . 
         FIG. 4  is a sectional detail of the seal shown in  FIGS. 1-3 . 
         FIG. 5  is a front elevation of the seal section weldment. 
         FIG. 6  is a cross sectional view of the seal section weldment shown in  FIG. 5 . 
         FIG. 7  is a front elevation of a seal backing plate weldment. 
         FIG. 8  is a cross sectional view of the seal backing plate weldment shown in  FIG. 7 . 
         FIG. 9  is a side elevation of a seal retainer plate. 
         FIG. 10  is a side view of a seal spring. 
         FIG. 11  is a front view of a seal spring shown in  FIG. 10 . 
         FIG. 12  is a front view of a blank for forming the seal spring shown in  FIGS. 10 and 11 . 
         FIG. 13  is a perspective detail of the seal shown in  FIGS. 1-12 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIGS. 1-4 , oven seal  30  is used to seal the opening clearance  22  between the oven structure  20  and the rotating drum  10  in which materials are heated. Only end portions of drum  10  and oven  20  are shown. 
     As shown in  FIG. 4 , the oven end structure  20  has an outer seal holder ring  24  with an L-shaped cross section. A cylindrical portion  26  is welded at an inner end  27  to the oven end structure  20 . A circular flange  28  at the outer end of cylindrical portion  26  has openings for receiving bolts  46  to mount the seal  30 . 
     As shown in  FIGS. 4 ,  7  and  8 , an annular seal backing plate  32  is mounted against flange  28 . The backing plate has two annular sections  34  and  36 , which are welded together. Section  34  lies flat against the flange  28  and has a radially inward extended guide portion  35 . Section  36 , which has a larger inner diameter, is welded axially outwardly on section  34  to act as a spacer. Mounting bolt receiving holes  38  extend through both sections  34  and  36 . The annular backing plate  32  may be constructed as one ring or as end to end segments. 
     As shown in  FIGS. 4 and 9 , an annular seal retainer  42  is formed in adjoined segments. Seal retainer  42  lies against the outer spacer section  36 , which has the larger inner diameter. Bolt holes  44  in seal retainer  42  allow the seal retainer  42  to be connected with bolts  46  to the seal backing plate  32  and to flange  28  of oven seal holder ring. As shown in  FIG. 4 , a cylindrical space  50  remains between the radially inward extending portion  35  of the inner section  34  of seal backing plate  32  and the seal retainer  42 . Space  50  provides a packing cavity  52  and a sealing elements receiver space  54 . 
     As shown in  FIGS. 4-6 , sealing elements  60  are constructed in segmental sections  62 . Partially cylindrical plates  64  are welded  67  to radially outward extending holder plates  66 . The radial holder plates  66  have central openings  68  for receiving round bars  70 , which slide radially in radial slots  48  in seal retainers  42 , which are shown in  FIG. 9 . Bars  70  and grooves  48  prevent sealing elements, from rotating with the drum  10 . 
     Inner cylindrical faces  72  of the sealing elements  60  ride on the outer surface  12  of an annular wear plate  90  on the drum  10  end, as shown in  FIGS. 4 and 13 , preventing ingress or egress of air, gas or vapor. 
     Packing material fills the packing space  52 . The packing material may be resilient to keep faces  72  of the sealing elements  60  pressed against the outer surface  12  of the annular wear plate  90  on the drum  10 . 
     Springs  80 , as shown in  FIGS. 1-4  and  10 - 12 , are connected by bolts  46  to lie against the seal retainers  42  and press the sealing elements  60  and their inner surfaces  72  against the outer surface  12  of drum  10  or a wear plate  90  on the drum. 
     Springs  80  are made from flat blanks  81 . Holes  82  are lanced to receiving mounting bolts  46 . The blanks are bent up 65° at line  83  and down 130° at line  85  to form outer and inner leg sections  84  and  86 . The inner edges  88  of inner sections  86  bear against an outer surface of plates  64  of sealing elements  60  to urge the inner faces  72  towards the wear plate  90  and drum  10 . 
     The inner leg sections  86  of the springs  80  are longer than the outer leg sections  84 . The spring inner edges  88  engage welded intersections  67  between the radial holder section  66  and the axially extending curved plates  64 . That tends to keep the sealing elements aligned in the radial spaces  50 , with the inner faces  72  of the sealing elements  60  firmly against the outer surface  12  of the drum  10  or the wear plate  90  on the drum as the drum rotates and also as drum ends and oven ends move relatively longitudinally during temperature variations. 
     Actions of the spring  80  are shown in  FIG. 13 .  FIG. 13  also shows a receiver  14  welded on the outer surface of the drum. 
     Lateral portions  65  of the curved sealing plates  64  fit in recess  15  of the receiver  14 , providing a secondary rotary seal between the drum  10  and the oven structure  20 . 
     The invention provides new air seals including new air seal  30  for a rotary dryer/kiln designed to prevent air from entering the dryer or kiln at either the feed or discharge openings. The new seal is a steel contact device comprised of formed radius sections  64 . Inner faces  72  of the sections  64  ride on an outer surface  12  of a wear plate  90  secured to the rotating drum  10 . The new seal  30  uses a single floating labyrinth resistance closure. This type of closure allows for radial expansion of the drum  10  and uneven drum surface contact. The seal sections  60  are spring loaded with bent stainless steel spring clips  80 . The seal also accommodates drum longitudinal expansion as well. 
     The seals  30  may be used as kiln seals, kiln breeching seals, kiln air seals, kiln or dryer leaf seals, kiln carbon block seals, high temperature radial kiln seals, vacuum kiln seals, pressure kiln seals. 
     While the invention has been described with reference to specific embodiments, modifications and variations of the invention may be constructed without departing from the scope of the invention, which is defined in the following claims.