Abstract:
An apparatus for cleaning deposits from the interior surfaces of a kiln. The apparatus utilizes a directed high-pressure fluid jet to remove deposits adhering to elements within a kiln. The pressurized fluid is delivered to the fluid jet through the shaft of a rotary drill. The drill shaft is received in a sleeve permitting rotational and longitudinal displacement of the shaft. The sleeve also defines a plenum surrounding the drill shaft to communicate pressurized fluid to the fluid jet throughout longitudinal and rotational displacement of the drill shaft. The drill further utilizes a boring bit suitable for penetrating encrusted deposits to provide the fluid jet access to the interior surfaces of the kiln. For removing severe encrustations, the drill bit may be used to partially penetrate the encrustation and a linear actuator may then be employed to press large portions of the encrustation from the kiln&#39;s refractory lining.

Description:
This application is a divisional application of prior application Ser. No. 10/072,148, filed Feb. 6, 2002, now U.S. Pat. No. 6,839,930. 

   TECHNICAL FIELD 
   This invention relates to the field of industrial kilns. More particularly this invention relates to an improved apparatus for cleaning deposits from the inner refractory surfaces of a kiln. Specifically, the apparatus disclosed may be used to drill, press, or blast deposits from the inner surfaces of a kiln. 
   BACKGROUND OF THE INVENTION 
   In the field of industrial kilns, particularly cement kilns, the accumulation of particulate deposits on the inner refractory lining of the kiln is a recurring problem. Buildup in the preheater and riser duct areas can choke off feed pipes and cyclones and greatly affect the efficiency and production performance of the kiln, even to the point of causing unscheduled shutdowns. If the deposits are permitted to accumulate, the high temperatures typically encountered by the interior of the kiln during normal operations will cause the deposits to become encrusted on the kiln&#39;s interior surfaces. The exact characteristics of the buildup in preheater towers may vary from plant to plant, and can even vary from hour to hour within the same plant. 
   Usually, the buildup begins sticking to the walls of the tower with the consistency of talcum powder. Routine cleaning of the deposits is a preferred method of addressing the problem, whereby the deposits are removed before significant accumulation and encrustation occurs. Various strategies in the art for removing deposits during routine cleaning cycles include pneumatic blasting, carbon dioxide explosions, manual air lances, manual jackhammers, and high pressure water blasting. All of these methods cause damage to the refractory lining and expose the operators to dangerous conditions. Moreover, these methods are reactionary to the buildup problem and are intended to minimize rather than eliminate it. These devices generally require access to the interior of the kiln to be effective. 
   In the case of blast cannons, access is provided to the interior of the kiln through a plurality of spaced apart ports. The ports typically are provided with a refractory protective sleeve for communication between the interior and exterior of the kiln walls. Blast cannons may be provided for each port, or may be moved from port to port to clean various portions of the kiln sequentially. A significant limitation of blast and percussive devices is the difficulty of directing their energy to release particular deposits and their limited effective blast radius. 
   Increased operational requirements or excessive particulate release may cause the rate of deposit accumulation to exceed the capability of routine cleanings to adequately remove deposit build up. This may lead to encrustation of the deposits on the kiln&#39;s refractory walls and occlusion of the access ports. Moreover, incomplete removal of deposits during routine cleaning will also accelerate deposit accumulation and consequent encrustation of the refractory walls as well as occlusion of the access ports. 
   In the case where the access ports have become fully occluded, many of the devices presently used for routine preventative cleaning are unable to clear the occlusion. In these instances a separate device for penetrating an encrustation to gain access to the interior of the kiln must be installed. In severe cases, the kiln will have to be brought off line before restorative cleaning may be initiated. 
   The requirement for additional equipment to gain access to the kiln and the manpower required to temporarily install then replace that equipment with the desired cleaning equipment adds significant cost and complexity to the cleaning operation. Moreover, the requirement to bring a kiln off line will adversely effect production capacity. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention addresses these problems in the industry by providing a single apparatus for both preventative and restorative cleaning of the interior refractory wall of a kiln. The device is adapted to be received on a wide variety of kiln access ports, making it particularly suitable for retrofitting to an existing kiln structure. As such, the apparatus of the present invention may be installed while the kiln remains operational. Moreover, the device provides multiple means of access to the interior of the kiln for such cleaning. First, the apparatus provides a rotatable pressurized fluid jet, which directs a pressurized fluid stream to remove deposits accumulating on a kiln refractory lining. The fluid jet of the present invention may be rotated continuously through a full 360 degree range of motion. Second, the apparatus provides for variable insertion of the fluid jet relative the kiln interior, enabling selective adjustment of the effective blast radius of the pressurized fluid stream, thereby permitting more effective removal of deposits. Third, in the event of partial access port occlusion due to deposit build up, the apparatus provides a rotating drill bit to bore through the occlusion, providing fluid jet access to the interior of the kiln without the need for additional boring equipment. Finally, in the event of total port occlusion and encrustation of built up deposits, the drill bit may be used to partially bore through the port occlusion and a linear actuator may then used to press large blocks of encrustation from the refractory wall. 
   Accordingly, the apparatus of the present invention comprises a rotary drive unit operatively connected to a first end of a longitudinally extending drill shaft. A drill bit is provided at a second end of the drill shaft and oriented for coaxial rotation therewith. The drill shaft is slidably received in a sleeve member, permitting rotational displacement of the drill shaft. A fluid jet, provided proximal the drill bit, projects a pressurized fluid stream, delivered through the drill shaft, for removing accumulated deposits from the kiln&#39;s refractory walls. 
   The apparatus&#39; ability to continuously project a pressurized fluid stream throughout its full rotational displacement is provided by the sealing engagement of the sleeve member with the drill shaft. A pressurized fluid source is communicated to the fluid jet via an inlet port on the sleeve member to a plenum defined between the sleeve member and the drill shaft sealingly received therein. The fluid is then communicated via an aperture in the drill shaft to a chamber defined within the drill shaft and in communication with the fluid jet. The rotation of the aperture within the plenum permits continuous delivery of the pressurized fluid to the fluid jet. 
   The ability of the apparatus to continuously project a pressurized fluid stream through a range of lateral displacement is achieved by maintaining the position of the drill shaft aperture within the lateral boundaries of the plenum. The thickness of the kiln wall is the primary factor in determining the drill shaft length and amount of lateral displacement the apparatus must achieve. With longer drill shaft lengths, a longer sleeve member and a wider plenum are desirable to adequately support to the drill shaft. 
   Lateral displacement of the drill shaft may be assisted by a linear actuator operatively connected between the first end of the drill shaft and the second end of the drill shaft. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments of my invention are depicted in the appended drawings which form a part of this disclosure and wherein: 
       FIG. 1  is a side sectional view of the apparatus attached to a kiln wall with the drill shaft in the retracted position; 
       FIG. 2  is a side sectional view of the apparatus attached to a kiln wall with the drill shaft in the extended position; 
       FIG. 3  is a perspective view of the apparatus with the drill shaft in the extended position; 
       FIG. 4  is a perspective view of the apparatus with the drill shaft in the retracted position; 
       FIG. 5  is a partial sectional view of the drill shaft showing the fluid jet and a drill bit; and 
       FIG. 6  is a partial sectional view of the sleeve, plenum and seal. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the drawings for a more complete description of the invention the kiln cleaning apparatus  10  is shown mounted to a wall  11  of an industrial kiln  12 . Kiln wall  11  includes a duct wall  13  and a refractory lining  14 . An industrial kiln  12  may include a plurality of access ports  16  spaced apart throughout wall  11  permitting access to the interior of kiln  12  for cleaning deposits which have accumulated on refractory lining  14  during operation of kiln  12 . Each access port  16  will typically include a protective sleeve  17  to prevent damage to refractory lining  14 . Support for protective sleeve  17  is provided by a flange  15 , which is secured to wall  11 . 
   As may be seen in  FIG. 1 , the cleaning apparatus  10  comprises a rotary drive unit  18  with its output shaft  19  operatively connected to a first end  21  of a drill shaft  20 , via a coupling unit  30 . Coupling unit  30  includes a coupling plate  31 , a bearing  33 , and a bearing retainer  34 . Coupling unit  30  is attached to rotary drive unit  18  via attachment means such as screws, bolts, or pins. 
   At a second end  22  of drill shaft  20  a drill bit  40 , suitable for drilling a build up of deposits and encrustation of the same, is attached for coaxial rotation with drill shaft  20 . An exemplary drill bit  40  is depicted in greater detail in  FIG. 5 . However, any drill bit suitable for boring built up deposits and encrustation of said deposits may be utilized with equally effective results. As depicted, a shank  41  of drill bit  40  is received within a chamber  25  defined internal drill shaft  20 . Shank  41  is secured within chamber  25  via attachment means  46 , which may include a set screw, a shear pin, or a threaded shank. 
   Drill bit  40  preferably includes a pilot bit  42 , to avoid drill bit  40  drift and undesirable contact of drill bit  40  with protective sleeve  17  during boring procedures. Pilot bit  42  will have a substantially smaller diameter than boring bit  43 . Boring bit  43  is comprised of a plurality of fingers  44  radially extending from shank  41 . Fingers  44  will have least one cutting surface  45  located thereon. Boring bit  43  should have a diameter closely matching a diameter of protective sleeve  17 . 
   Referring again to FIGS  1  and  2 , a portion of drill shaft  20  is received by a sleeve member  60  interposed between drill shaft first end  21  and drill bit  40 . Sleeve member  60  is attached to an adapter housing  90  proximal drill bit  40  for operative connection of the kiln cleaner  10  to kiln  12  via flange  15 . Adapter housing  90  provides alignment of drill shaft  20  relative access port  16 , permitting extension of drill shaft  20  and concomitant drill bit  40  boring through deposits which may occlude access port  16  and protective sleeve  17 . 
   The cooperative engagement of drill shaft  20  with sleeve member  60  provides fluid communication means between a pressurized fluid source and a fluid jet  50 . At least one inlet port  67 , defined between an inner wall  61  and an outer wall  62  of sleeve member  60  receives a pressurized fluid source. A plenum  69 , defined between inner wall  61 , an outer surface  23  of drill shaft  20  and first and second sealing means  65  &amp;  66 , receives the pressurized fluid from inlet port  67 . An aperture  26 , defined between outer surface  23  and an inner surface  24  of drill shaft  20 , receives the pressurized fluid from plenum  69 . Chamber  25  in turn receives the pressurized fluid from aperture  26  for subsequent communication to fluid jet  50 . 
   Since plenum  69  surrounds drill shaft  20 , fluid communication through aperture  26  may be maintained regardless of the rotational displacement of drill shaft  20 . Moreover, fluid communication through aperture  26  may be continuously maintained throughout longitudinal displacement of drill shaft  20 , provided that aperture  26  remains positioned between first and second sealing means  65  &amp;  66 . 
   As shown in  FIGS. 1 and 2 , a pair of bearings  68  are selected and positioned proximal a first end  63  and a second end  64  of sleeve member  60  and support rotational and longitudinal displacement of drill shaft  20 . Bearings  68  may also provide first and second sealing means  65  &amp;  66  for plenum  69 . In comparing the drawings of  FIGS. 1 and 2 , it may be seen that drill shaft  20  has been longitudinally displaced between a retracted position, as depicted in  FIG. 1 , and an extended position, as depicted in  FIG. 2 . Comparison of  FIGS. 1 and 2  further shows that fluid communication is continuously maintained throughout displacement of drill shaft  20  by maintaining aperture  26  between first and second sealing means  65  &amp;  66 . 
   Exemplary sealing means are shown in the detailed drawing of  FIG. 6 , wherein drill shaft  20  is sealingly received within bearing  68  while O-rings  70  sealingly engage bearing  68  and sleeve member inner wall  61 . However, this arrangement is illustrative only, as first and second sealing means  65  &amp;  66  may be employed independent of bearing  68  and may be placed at any position relative sleeve member  60 , it being understood that aperture  26  need only be maintained between first and second sealing means  65  &amp;  66  when fluid communication through aperture  26  to fluid jet  50  is required. 
   The length of drill shaft  20  is selected to obtain a desired penetration into kiln  12  so that the pressurized fluid stream pattern, developed by fluid jet  50 , may be employed against deposits adhering to kiln refractory lining  14 . As such, the thickness of kiln wall  11  and the anticipated thickness and consistency of the adherent deposits will influence the length of drill shaft  20 . 
   As may be seen in the drawings, a fluid jet  50  is attached at second end  22  of drill shaft  20  proximal drill bit  40  and projecting laterally of drill shaft  20 . Fluid jet  50  is in fluid communication with chamber  25 , which receives the pressurized fluid source as described above. Fluid jet  50  imparts a desired flow pattern to the pressurized fluid source, which may then be directed to release deposits adhering to refractory lining  14 . Since fluid jet  50  is in rotational engagement of with drill shaft  20 , deposits may be removed from refractory lining  14  through a full  360  degrees of rotation around access port  16 . The surface area radius of refractory lining  14  which may be cleared is dependent upon the effective blast radius of the pressurized fluid flow pattern developed by fluid jet  50 . 
   As is best seen in the detail drawing of  FIG. 5 , fluid jet  50  comprises a fluted venturi aperture  51  received in a first bore  27 , extending from an outer surface  23  of drill shaft  20  to an inner surface  24  of drill shaft  20 . Inner surface  24  defines chamber  25  internal drill shaft  20 . Fluted venturi aperture  51  is depicted as a threaded insert, however, any suitable attachment means may be utilized to secure fluted venturi aperture  51  in first bore  27 , including an interference fit or a weld. Fluted venturi aperture  51  comprises a flared inlet portion  52 , a tapered outlet portion  53 , and a constricted throat portion  54  intermediate flared inlet portion  52  and tapered outlet portion  53 . Preferably, flared inlet portion  52  will have a greater inlet diameter than an outlet diameter of tapered outlet portion  53 . 
   For improved developement of the desired flow pattern in the pressurized stream, fluid jet  50  further comprises a stylus  55  received coaxial with fluted venturi aperture  51 . Stylus  55  comprises a bulbous portion  56  and a tapered end portion  57  axially extending from bulbous portion  56 . A lug portion  58  is received in a second bore  28  defined in drill shaft  20  and coaxial first bore  27 . Lug portion  58  may be fit in second bore  28 , but is preferably inserted via a threaded interface to permit adjustment of stylus  55  to obtain a desired flow pattern and corresponding blast radius. Typically, stylus  55  is positioned within fluted venturi aperture  51  such that bulbous portion  56  is juxtaposed constricted throat portion  54 . 
   As seen in the drawings, a linear actuator  80  is operatively connected between coupling unit  30  adapter housing  90 . Linear actuator  80  permits selective extension and retraction of drill shaft  20  as seen by comparison of  FIGS. 1 &amp; 2  as well as  FIGS. 3 &amp; 4 . Connection of a first end  81  of linear actuator  80  is provided by a first linear actuator boss  35  located on coupling  30 . Attachment means  83 , such as pins or bolts, secure first end  81  to receiving point  36 . Connection of a second end  82  of linear actuator  80  is provided by a second linear actuator boss  91  located on adapter housing  90 . Attachment means  83 , such as pins, bolts or screws secure second end  82  to a receiving point  98 . 
   In operation, linear actuator  80  may be selectively engaged to assist boring by urging drill bit  40  against deposit build up which may be occluding or only partially occluding access port  16 . Once the occlusion has been cleared, linear actuator  80  may then complete insertion of fluid jet  50  to a desired depth into kiln  12 , thereby permitting the removal of adherent deposits by the pressurized fluid stream. 
   In the event that large deposits or an encrustation of deposits completely occlude port  16  and the refractory lining  14  surrounding port  16 , drill bit  40  may be utilized to partially bore into the deposits or encrustation. Linear actuator  80  may then be used as a press to break off large portions of encrustation from refractory lining  14 . In the event of severe encrustation, utilization of this procedure may permit continued operation of kiln  12  for a period of time until the kiln may be brought off line to permit more complete encrustation removal from refractory lining  14 . 
   A guide rod  37  assists in maintaining alignment of drill shaft  20  during activation of linear actuator  80 . Guide rod  37  is attached to a receiving point  38  on coupling plate  31  and is slidingly received in a bore  73  of at least one guide rod alignment point  72  extending from sleeve member outer wall  62 . Additionally, guide rod  37 , in cooperation with linear actuator  80 , counteracts the torque developed by rotary drive unit  18  during rotary engagement of drill bit  40  against deposits and encrustation. 
   To assist in maintaining the proper kiln temperature and to protect the kiln cleaner  10  from the deleterious effects of the extreme kiln temperatures, the kiln cleaner  12  contemplated by the present invention may also provide a selectively positionable insulated access port cover plate  101 . The access cover mechanism  100  comprises an access cover actuator  103  operatively connected between sleeve second end  64  and a first end of an access cover lever  102 . A second end of access cover lever  102  is connected to an extension of cover plate  101 . Access cover lever  102  works via fulcrum  104  for operative opening and closing access cover plate  101 . 
   Adapter housing  90  may also include a removable access panel  95 , which provides operator access to drill bit  40  and fluid jet  50 , permitting cleaning, maintenance, or adjustment of the same without the need to remove the apparatus from its attachment to the kiln  12 . 
   It should be understood that although I have described an exemplary embodiment of my invention in some detail, modifications and variations might be made without departing from the spirit of my invention. Accordingly, I claim as my invention all forms thereof coming within the scope of the appended claims.