Abstract:
A boiler apparatus includes a housing defining an interior boiler chamber and a burner element arranged to be in thermal communication with the boiler chamber. An ignition device is provided for instigating combustion of an inlet gas stream, and is arranged adjacent one edge of the burner element. A gas restricting device is utilized for restricting contact between the burner element and the inlet gas stream such that the inlet gas stream is initially incident upon the one edge of the burner element, thereby forcing the inlet gas stream to propagate across the burner element from the one edge.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application Ser. No. 60/549,573, filed on Mar. 2, 2004, herein incorporated by reference in its entirety. 
   FIELD OF THE INVENTION 
   This invention relates in general to a boiler and burner apparatus, and deals more particularly with a down-fired boiler and burner apparatus that reduces the sensibility to boiling as well as increasing the efficiency of the burner assembly. 
   BACKGROUND OF THE INVENTION 
   In known cast iron boilers, typically utilized in residential or commercial settings to provide heated water for heating purposes or the like, the inhibition of a boiling action in the boiler fluid is paramount. As will be appreciated, boiling of the boiler fluid causes a substantial, and frequently rapid, expansion of the boiler fluid volume, which may precipitate possible catastrophic damage to the system as a whole. Thus, differing boiler configurations have been employed to prevent the occurrence of actual boiling in the boiler system. 
   One commonly employed method utilized to prevent boiling in boiler systems is the introduction of increased pressure within the boiler chamber and related piping. By increasing the pressure within the system, it is possible to heat the boiler fluid to a temperature above what its normal boiling point would be at ambient atmospheric pressure. Increased boiler chamber pressure thus enables the production of superheated boiler fluid, which may then be effectively utilized throughout the heating system while avoiding any damaging volumetric expansion of the boiler fluid. 
   Another known method of limiting the conditions conducive to boiling involves causing the boiler fluid to circulate, or flow, in a manner that will effectively disperse the heat in the boiler equally to all portions of the boiler fluid. The management of boiler fluid flow paths and velocity are integral to both below-fired boilers and down-fired boilers. 
   In below-fired boilers, the burner assembly is typically located adjacent the bottom of the boiler, thereby causing rapid mixing and circulation of the boiler fluid due to buoyant convection in the total liquid volume. Fluctuations in the return water temperature, BTU input or saturation temperature are thereby absorbed in the total heat capacity of the boiler. 
   In down-fired boiler configurations, the burner assembly is instead located adjacent the upper portion of the boiler, effectively having no volume of water above the area where heat is being generated. Consequently, the heat being added to the system is dispersed and circulated via convection. In an effort to increase the circulation and efficiency of down-fired boilers, a series of inner baffles are known to be utilized within the boiler chamber to create a measure of fluid velocity across the inner surface of the boiler chamber. 
   The use of baffles, while increasing somewhat the velocity and circulation of the boiler fluid, presents its own set of concerns. The sheer number and configuration of the inner baffles increase the difficulty, and related costs, of the casting process when manufacturing typical cast iron boilers. Moreover, the inner baffles themselves may create pockets of non-circulating, or low-circulating, fluid. This is true particularly in the areas adjacent where the baffles contact the side walls of the boiler chamber. As known to those of skill in the art, localized areas of low or non-circulating boiler fluid creates an environment that may promote undesirable boiling. There thus exists a need to design a down-fired boiler that not only promotes boiler fluid circulation, but also reduces the incidence of low-circulating pockets of fluid. 
   Another concern for down-fired boilers is the operation of the burner assembly itself. In such systems, the fuel mixture is typically dispersed across the entire surface of the burner element at essentially the same time. Since the initial ignition of the fuel mixture occurs at one location adjacent the burner element, the fuel mixture located away from the ignition site typically propagates some distance away from the burner element prior to igniting. 
   As will be appreciated, the ignition of pockets of fuel located some distance away from the burner element causes a rough and oftentimes noisy ignition that, over time, may cause damage to the burner element as well as being audibly disconcerting. 
   With the forgoing problems and concerns in mind, it is the general object of the present invention to provide a down-fired boiler and burner apparatus that reduces the sensibility to boiling as well as increases the efficiency of the burner assembly. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a down-fired boiler and burner apparatus. 
   It is another object of the present invention to provide a down-fired boiler and burner apparatus that reduces the sensibility to boiling as well as increasing the efficiency of the burner assembly. 
   It is another object of the present invention to provide a down-fired boiler that reduces the possibility of boiling in the boiler fluid. 
   It is another object of the present invention to provide a down-fired boiler and burner apparatus that increases the circulation and velocity of boiler fluid. 
   It is another object of the present invention to provide a down-fired boiler and burner apparatus that produces a substantially silent ignition of the fuel mixture. 
   In accordance with a preferred embodiment of the present invention, a boiler apparatus includes a housing defining an interior boiler chamber and a burner element arranged to be in thermal communication with the boiler chamber. An ignition device is provided for instigating combustion of an inlet gas stream, and is arranged adjacent one edge of the burner element. A gas restricting device is utilized for restricting contact between the burner element and the inlet gas stream such that the inlet gas stream is initially incident upon the one edge of the burner element, thereby forcing the inlet gas stream to propagate across the burner element from the one edge. A turning vane is also provided and is disposed adjacent an inlet aperture for the boiler fluid. The turning vane diverts the boiler fluid such that the boiler fluid is caused to initially flow adjacent an interior surface of the boiler chamber. 
   These and other objectives of the present invention, and their preferred embodiments, shall become clear by consideration of the specification, claims and drawings taken as a whole. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of a down-fired boiler, according to one embodiment of the present invention. 
       FIG. 2  is a partial cross-sectional view of a burner assembly for a down-fired boiler, in accordance with one embodiment of the present invention. 
       FIG. 3  is a partial cross-sectional view of the burner assembly shown in  FIG. 2  as it is mounted adjacent the upper portion of a down-fired boiler. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  illustrates a cross-sectional view of a down-fired boiler  10 , in accordance with one embodiment of the present invention. As shown in  FIG. 1 , the boiler  10  includes a boiling housing  12  defining an inner boiler chamber  14 . A boiler fluid inlet manifold  16  and a boiler fluid outlet manifold  18  are also shown in  FIG. 1 . A presently non-illustrated burner assembly is disposed adjacent the upper portion  20  of the boiler  10 , and will be described in more detail later. 
   It will be readily appreciated that the boiler fluid most commonly utilized is water, although the present invention is not limited in this regard as alternative fluids may be utilized without departing from the broader aspects of the present invention. 
   Returning to  FIG. 1 , the inner volume of the boiler chamber  14  includes a plurality of structural stays  22  that are spaced throughout the inner volume of the boiler chamber  14 . The stays  22  provide structural support to the boiler  10  when the boiler chamber  14  is subjected to an increased pressure regimen, as is typically known in the art. Although the stays  22  are shown in a substantially uniform pattern, the location, spacing, size and number of the stays  22  defined in the boiler chamber  14  may be readily altered to accommodate a particular design or performance characteristic without departing from the broader aspects of the present invention. 
   In a preferred embodiment of the present invention, the boiler fluid inlet manifold  16  extends substantially the entire width of the boiler  10  and receives an inlet water supply via one or more conduits  24 . Running substantially parallel to the boiler fluid inlet manifold  16  is a turning vane  26  that is defined within the boiler chamber  14 . The turning vane  26  is also preferably fashioned to extend substantially the entire inner width of the boiler chamber  14  and defines an inlet opening  28  into which the inlet water supply may be incident via one or more manifold apertures  30  formed in the boiler fluid inlet manifold  16 . 
   In a preferred embodiment, the boiler fluid inlet manifold  16  would define a plurality of distinct manifold apertures  30  for directing the inlet water into the boiler chamber  14 . Moreover, the inlet opening  28  of the turning vane  26  would be preferably defined as a continuous, elongated slot that extends substantially the entire inner width of the boiler chamber  14 . In this manner, the inlet opening  28  would readily accept the inlet water as directed by manifold apertures  30 . The present invention, however, is not limited in this regard. Alternative configurations, such as forming the manifold apertures  30  as a single, continuous and elongated slot, or by defining a plurality of distinct inlet openings  28  in the turning vane  26 , are equally contemplated by the present invention. 
   It is therefore an important aspect of the present invention that the boiler fluid inlet manifold  16  is capable of directing the inlet water flow to the turning vane  26  such that an increased fluid flow and circulation is enabled within the boiler chamber  14 . That is, the structural configuration of the turning vane  26  promotes the channeling of the inlet water along the inner surfaces of the boiler housing  12 , in a direction substantially perpendicular to the direction of the inlet water flow coming out of the manifold aperture  30 . The channeled water will have a higher velocity than the ambient fluid within the boiler chamber  14  and thus, the channeled water will entrain the surrounding fluid and create a recirculation flow of fluid in the boiler chamber  14 . 
   As will further be appreciated, the channeled water will more readily attach itself to the inner walls of the boiler housing  12 , thus making the entrainment of the surrounding fluid more difficult adjacent the inner walls. In this manner, the surrounding fluid will more readily entrain from the open, inner side of the channeled water and produce a high velocity flow  32  within the boiler chamber  14 . 
   It is therefore another important aspect of the present invention that the turning vane  26  creates a pump-like action within the boiler chamber  14  such that the high velocity flow  32 , having substantial volume, is produced within the boiler chamber  14 . The high velocity flow  32  will more easily absorb heat added by the burner assembly, as well as homogenizing variations in temperature and fluid flow within the boiler chamber  14 . The combined effects of the pump-like action of the high velocity flow  32  is to enable the boiler  10  to be operated at higher temperatures for a given pressure than has been heretofore known with existing designs. 
   The advantageous effects of the turning vane  26  are due in large part to its structural configuration and physical location within the boiler chamber  14 . As shown in  FIG. 1 , the inlet opening(s)  28  of the turning vane  26  is oriented adjacent the manifold aperture(s)  30 , such that the velocity of the inlet boiler fluid carries the boiler fluid into the turning vane  26 . Moreover, the turning vane  26  defines a radial turn  31  that effectively redirects the inlet boiler fluid up into the boiler chamber  14 , and adjacent the inner wall  33  of the boiler chamber  14 . 
   Still yet another important aspect of the present invention is that the configuration of the boiler  10  eliminates the need to cast, or otherwise form, interior baffles within the boiler chamber  14 . The elimination of such structures not only significantly reduces the complexity and cost of manufacturing the boilers themselves, but also eliminates those areas of low or non-circulating boiler fluid, thus effectively eliminating the possibility of boiling owing to such concerns. 
   A burner assembly  40  will now be described for use with down-fired boiler systems.  FIG. 2  is a partial cross-sectional view of the burner assembly  40 , in accordance with one embodiment of the present invention. As shown in  FIG. 2 , the burner assembly  40  includes a burner enclosure  42  and a combustion chamber  44 . Taken together, the burner enclosure  42  and the combustion chamber  44  substantially enclose a pilot gas assembly  46 , a burner element  48  and a spark igniter and flame detection assembly  50 . 
   The pilot gas assembly  46  is utilized to present the pilot gas to the burner element  48  and the spark igniter and flame detection assembly  50 . As shown in  FIG. 2 , a pilot gas orifice  52  directs inlet pilot gas through a pilot mixing tube  54  and to the upper surface of the burner element  48 . The pilot gas emerges from the underside of the burner element  48  and is then ignited by the spark igniter and flame detection assembly  50 , either manually or through an automated system, as is known in the art. A pilot spring  56  is utilized to assuredly hold the pilot mixing tube in contact with the burner element  48 . 
   In contrast to known systems, the burner assembly  40  includes a flow director  58  which is preferably arranged substantially across the entire width of the burner element  48 . As further illustrated in  FIG. 2 , the flow director  58  has a downwardly extending closed end  60  which effectively isolates the burner element  48  from initial contact with the incoming fuel stream  62 . On the opposing lateral side from the closed end  60 , the flow director  48  has an open end  64  which also extends substantially the entire width of the burner element  48 . 
   The fuel stream  62  is thus deflected and directed across the upper side of the flow director  58 , becoming incident upon the burner element  48  only along the exposed lateral side of the burner element  48  adjacent the open end of the flow director  58 . As can be seen in  FIG. 2 , the open end  64  is arranged to be adjacent the location of the pilot gas assembly  46  and the spark igniter and flame detection assembly  50 . 
   In this manner, the burner assembly  40  of the present invention assures that the fuel stream  62  will first emerge from the underside of the burner element  48  adjacent the location of the spark igniter and flame detection assembly  50 . Continued supply of the fuel stream  62  will cause a corresponding and temporally sequential emergence of the fuel stream  62  in a direction across the burner element  48 . As will be appreciated, ignition of the fuel stream via actuation of the spark igniter and flame detection assembly  50  will therefore first occur adjacent the spark igniter and flame detection assembly  50 , and thereafter propagate in the same direction as the sequential emergence of the fuel stream  62  from the underside of the burner element  48 , as indicated by flame propagation arrow F. 
   It is therefore another important aspect of the present invention that the flow director  58  effectively acts as a gas restricting means for controlling access of the fuel stream  62  to the burner element  48  such that the fuel stream  62  is forced to first contact a predetermined lateral side or edge of the burner element  48  prior to propagating across the burner element  48 . In doing so, the flow director  58  ensures that the fuel stream cannot first penetrate the burner element  48  at a location away from the spark igniter and flame detection assembly  50 , thus eliminating subsequent migration of the fuel stream  62  away from the surface of the burner element  48  and the noise inherently caused by the ignition of pockets of migrated fuel. 
   The burner assembly  40  of the present invention thus enables a substantially silent ignition of the fuel stream  62  by essentially coupling the emergence of the fuel stream  62  with the ignition thereof by the spark igniter and flame detection assembly  50 . 
   Still yet another important aspect of the present invention is that the burner assembly  40  not only enables a substantially silent ignition of the fuel stream  62 , but it also substantially eliminates any concussive damage caused by the ignition of pockets of fuel that would otherwise have migrated away from the burner element  48  if not for the flow director  58 . 
   In the preferred embodiment, the burner element  48  is formed of a ceramic material and the flow director  58  is formed from a metallic material, although the present invention is not limited in this regard. That is, the present invention equally contemplates that the burner element  48  and the flow director  58  may be formed from any suitable materials without departing from the broader aspects of the present invention. 
     FIG. 3  illustrates a partial cross-sectional view of the burner assembly  40  shown in  FIG. 2  as it is typically mounted, at an angle, adjacent the upper portion  20  of the down-fired boiler  10 , shown in  FIG. 1 . 
   As will be appreciated by a review of  FIGS. 1–3  and the associated discussion above, the present invention provides an improved down-fired boiler and burner apparatus that reduces the sensibility to boiling as well as increases the silent actuation of the burner assembly. Moreover, although the present invention has been described in connection with a down-fired boiler system, the present invention is not limited in this regard or application, as the turning vane and burner assembly of the present invention may be alternatively incorporated in burner systems of differing configurations without departing from the broader aspects of the present invention. 
   While the invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various obvious changes may be made, and equivalents may be substituted for elements thereof, without departing from the essential scope of the present invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention includes all equivalent embodiments.