Abstract:
A burner assembly for a grain bin for heating air moving through the assembly to dry grain in the bin. The burner assembly has a collector adapted to receive fuel from a fuel line. A burner housing attaches to the collector receives fuel from the fuel line. A nozzle is secured to the burner. A flame diverter downstream from the burner housing diverts the flame outwardly from the burner nozzle toward the housing wall. A flame cone having a slope generally similar to the slope of the diverter is positioned near the burner to define a gap between the inside face of the diverter and the outer surface of the flame cone so as to provide a path for the burning fuel to travel from the burner outwardly toward the housing walls for a more complete combustion of the fuel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Non-Provisional application claims priority to U.S. Provisional Application Ser. No. 61/608,938 filed Mar. 9, 2012, and which is incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND 
     A heater for a grain bin, grain dryer, or the like in which air is heated by a gas fired burner and then inducted into a grain bin, grain dryer, or other structure for drying or otherwise conditioning grain therein. Conventionally as shown in  FIGS. 1-5 , such heaters include an outer housing  130  which may be connected to a grain bin  10  for directing heated air therefrom into the grain bin  10 . A fan  34  forcefully moves air through the outer housing  130 , past a burner  144  therein, and directs the heated air into the grain bin  10 . Oftentimes, the grain bin  10  has a perforated floor  18  raised above a concrete pad  12  with the space between the floor  18  and the concrete pad  12  constituting a plenum  22 . The heater  24  directs heated air under pressure into this plenum  22  where it is substantially uniformly distributed under the entire cross section of the grain bin  10  such that the heated air may pass upwardly through the floor  18  and through the grain supported on the floor  18  so as to dry the grain. 
     Typically, most grain bin dryers are gas fired dryers which burn either liquefied petroleum (e.g., liquid propane) or natural gas, such as the grain bin dryer of U.S. Pat. No. 5,400,525 which is incorporated by reference herein. The dryer fan may be either an axially blower located upstream from the heater and generally in axial alignment with the heater, or the fan may be a centrifugal fan (not illustrated) coupled to the heater upstream from the heater. Such heaters  24  typically include a gas burner  144  positioned within the central portion of the heater outer housing  130  so that when the gas fuel is ignited, a flame is generated which heats the air forced by the fan through the heater outer housing  130  and into the grain bin  10 . It has been long known that by providing such gas fired grain bin heaters  10  with a flame diverter  170  that the flame can be more uniformly distributed within the outer housing  130  thus resulting in better heating of the air being forced through the heater  24 . Typically, such prior art flame diverters comprise a plurality of spaced slats  182  arranged in a generally conical configuration with the apex of the conical flame diverter  170  being positioned close to the burner  144  at the center of the heater outer housing  130  so as to direct the flame outwardly toward the walls of the outer housing  130 . Typically, these flame diverter slats  182  are provided with a multiplicity of holes  183  therein so as to aid in supplying air to the air/fuel mixture. 
     In a gas burner, the gas fuel has a certain calorific value typically expressed in BTU/cubic foot of the gas fuel. For example, natural gas may have a calorific value of about 1,000 BTU/cu. ft., and commercially available propane (L.P.) gas may have a calorific value of about 2,350 BTU/cu. ft. If these gaseous fuels are completely combusted, the products of combustion will include carbon dioxide, water, and nitrogen compounds from the combustion air. Of course, complete combustion insures the maximum release of heat from the fuel and results in the most efficient operation of the burner. Complete combustion of the fuel results in the maximum amount of air being heated. Usually, complete combustion of the fuel is visually evidenced by the flame burning with a bluish or colorless flame. If combustion is incomplete, as will be the case if there is not sufficient air for complete combustion, carbon monoxide and carbon will also make up part of the combustion products. It is well recognized that the presence of a “yellowish” flame is a sign that incomplete combustion (and thus less efficient combustion) is occurring such that the maximum efficiency of the burner is not being realized. 
     In many prior art grain dryer heaters such as above-described, it has long been noted that at least certain portions of the flame within the burner had a generally yellowish appearance which is an indication of incomplete combustion. Typically, such areas of incomplete combustion were immediately downstream from the burner nozzle located at the center of the grain bin heater housing. However, with the known prior art burners it has not heretofore been possible to regulate the position of the flame within the heater housing so as to achieve both complete combustion and to divert the flame outwardly toward the walls of the housing so as to result in a more evenly distributed heating of the air. The above-described flame diverters with their spaced slats did effectively direct the flames outwardly from the burner toward the walls of the housing, but such flame diverters (even when their spaced slats were provided with a multiplicity of holes therein) were not effective so as to insure that substantially complete combustion of the gaseous fuel would result even if the burner was regulated to admit more air into the burner for mixing with the fuel prior to the point the fuel was ignited. As above-noted, in conventional prior art grain bin dryers, a region of low pressure would develop immediately downstream from the burner nozzle such that when the fuel burned in this area, it would burn with a “yellowish” color flame generally indicative of incomplete combustion. 
     To address the low pressure region, U.S. Pat. No. 5,400,525 disclosed a burner which includes a conical-shaped flame cone within the low pressure region of the flame diverter downstream from burner nozzle on the inside of the flame diverter. By placing the flame cone on the downstream side of the flame diverter in the region of normally low pressure, the combusting air/fuel mixture is diverted from this low pressure region and is at least partially confined between the inner faces of flame diverter and the outer face of the flame cone such that excess air forced through openings in diverter slats and excess air flowing around the slats is mixed with the combusting air/fuel mixture thereby to result in more complete combustion of the air/fuel mixture. As a result of the flame cone, substantially the entire quantity of the air/fuel mixture burns with a generally colorless or “blue” flame which is visually indicative of more complete combustion of the fuel. Of course, such combustion results in the maximum amount of heat being released from the fuel such that the efficiency of the burner is increased as indicated in the chart of  FIG. 15  herein. In addition, as the air flowing through the housing encounters the flame diverter and flame cone, the air and the flames are intermixed and are forced to spread radially outwardly toward the housing walls. While this design increases the efficiency of the burner, the burner disclosed below provides even further increased efficiency. 
     Thus, there has been a long-standing problem as to how to maximize combustion to maximize efficiency of the heater and to simultaneously uniformly distribute the heated air with the air forcefully moved through the heater without duly restricting the flow of air through the blower/heater unit. 
     SUMMARY 
     Briefly stated, a heater assembly for a grain bin or similar device having an outer housing with an inlet end and an outlet end, the outer housing having one or more housing walls, a blower for forcefully moving air from the inlet end through the outer housing and out of the outlet end, a burner within the outer housing intermediate the inlet and outlet ends for burning a fuel within the outer housing and for heating the air moving through the housing. The burner includes a collector adapted to receive fuel from a fuel line; a burner housing attached to the collector to receive fuel; a nozzle attached to the burner housing to receive fuel, the nozzle having conduits extending from a surface of the nozzle, the conduit defining outlets for the fuel; a flame diverter within the outer housing downstream from the burner housing sized, shaped and adapted to divert the flame outwardly from the burner housing toward the walls of the outer housing, the flame diverter comprising a cone-shaped member diverging outwardly from the burner housing and toward the walls of the outer housing, the diverter defining a plurality of spaced openings through which air moved by the blower to may pass; and a flame cone having an apex and an outer base spaced axially from the apex with the slope of the flame cone being generally similar to the slope of the flame diverter, the apex of the flame cone being positioned near the nozzle on the inside of the flame diverter to define a gap between the inside face of the flame diverter and the outer surface of the flame cone; said gap defining a path for burning fuel to travel from the nozzle outwardly toward the outer housing wall, thereby to result in substantially complete combustion of the fuel. 
     The foregoing and other features and advantages of the disclosure as well as embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings which form part of the specification: 
         FIG. 1  is a cross-sectional view of a grain bin illustrating a raised perforated floor, a heater and fan arrangement for introducing heated air under pressure into a plenum beneath the grain bin floor so as to uniformly force heated air to rise through the grain within the bin supported by the raised floor; 
         FIG. 2  is a perspective view of a collector of a prior art burner; 
         FIG. 3  is a front view of a flame diverter of the prior art burner; 
         FIG. 4  is a enlarged front view of a flame diverter of the prior art burner; 
         FIG. 5  is a perspective view of a nozzle of the prior art burner; 
         FIG. 6  is a side view of a heater and burner assembly of the prior art burner; 
         FIG. 7  is an exploded perspective view of the heater and burner assembly of the prior art burner; 
         FIG. 8  is a perspective view of a collector assembly of the burner assembly; 
         FIG. 9  is a enlarged front view of a flame diverter of the burner assembly; 
         FIG. 10  is a perspective view of a nozzle of the burner assembly without a cone; 
         FIG. 11  is a perspective view of slats around the nozzle without a cone; 
         FIG. 12  is an end view of the slat without a cone; 
         FIG. 13  is a perspective view of the burner assembly with a cone; 
         FIG. 14  is a perspective view of a burner assembly without a cone; 
         FIG. 15  is a table illustrating test results of the prior art burner assembly; 
         FIG. 16  is a first table illustrating the test results of the burner assembly; 
         FIG. 17  is a second chart illustrating the test results of the new burner assembly; and 
         FIG. 18  is a third chart illustrating the test results of the new burner assembly. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. 
     DETAILED DESCRIPTION 
     The following detailed description illustrates the heater by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the heater, describes several embodiments, adaptations, variations, alternatives, and uses of the heater, including what is presently believed to be the best mode of carrying out the heater. Additionally, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The heater is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     As shown in  FIG. 1 , a grain bin  10  is installed on a foundation, such as, a concrete pad  12 , and is adapted to receive and store grain. The grain bin  10  includes sidewalls  14  extending upwardly from the pad  12  and a generally conical-shaped roof  16  adapted to seat on the sidewalls  14 . A raised floor  18  of interlocking side-by-side channel floor members is provided with perforations, such as a multiplicity of aeration holes (not shown). Support legs  20  support the floor  18  above the level of pad  12  to define a plenum  22  between the floor  18  and the pad  12 . 
     A combination blower/heater unit  24  supplies heated air under pressure via a transition section  26  to the plenum  22  in a substantially uniform distribution pattern through the plenum  22  and through the perforations in the floor members and through a quantity of grain within the bin supported by the floor  18  to dry the grain. To discharge moisture from within the grain bin  10 , the roof  16  defines a plurality of roof vents  28  for venting air from within the grain bin  10  after the heated air passes through the grain. 
     As shown in  FIGS. 6-7 , the blower/heater  24  has an outer housing  30  having a generally cylindrical wall  32  adapted to enclose an axial fan  34 . A motor  36 , preferably electric (but which could be any type of motor), is operatively connected to the fan  34  to communicate air though the outer housing  30  from an inlet end  36  to an outlet end  38  and into the transition section  26  between outer housing  30  and grain bin sidewall  14  to introduce the heated air into the plenum  22 . While the fan  34  is shown to be an axial fan, any suitable air moving device can be used, including, but not limited to a centrifugal blower. 
     The blower/heater  24  also includes a burner  40  located centrally within outer housing  30 , preferably on the axial centerline of the outer housing  30 , and downstream from the fan  34 . More specifically, the burner  40  includes a right angle burner housing  42  with a first portion  43  positioned generally on the axial centerline of the housing, and a second portion  45  extending upwardly toward the outer housing wall  32 . 
     A nozzle  44  is attached to the end of the first portion  43  of the burner housing  42  with the nozzle  44  positioned generally on the axial centerline of outer housing  30 . ( FIG. 10 ) The nozzle  44  is a generally in the shape of a cylindrical cup that defines a generally cylindrical surface  46  ( FIG. 10 ) with an angled surface  48  extending therefrom. The angled surface  48  is in the shape of a truncated cone. The cylindrical surface  46  defines a first set of holes  50 , preferably thirty-six ⅜″ evenly spaced holes, which are adapted, sized and shaped to deliver fuel from the burner housing  42  to a flame diverter  70 . The angled surface  48  defines a second set of holes  54  adapted to receive respective elongate conduits or tubes  56  which extend from the angled surface to deliver fuel from the burner outer housing  30  to the flame diverter  70 . Illustratively, each conduit  56  is a ⅜×3½″ pipe extension, but any suitable conduit can be used. 
     A collector  57  ( FIG. 8 ) is positioned between the second portion  45  ( FIG. 6 ) of the burner housing  42  and the housing wall  32 . The collector  57  is adapted to receive a fuel line/orifice  58  and to direct fuel into the burner housing  42 . Preferably, the collector  57  includes a generally C-shaped bracket  60  attached to the inner surface of the outer housing  30 , such as with fasteners or by welding. The bracket  60  defines an opening  62  adapted to mate with the burner housing  42 . An arcuate plate  64  or scoop attaches generally about the bracket opening  62 , such as with fasteners or by welding. The plate  64  extends upwardly towards the outer housing  30  at an angle, preferably of about 45°, and attaches to the sides of the bracket  60 , such as with fasteners or by welding. The plate  64  defines an opening  65  adapted to receive and secure the fuel line  58  relative to the opening  62  in a position to center and dispense fuel into the burner housing  42 . 
     The fuel line  58  extends through the housing wall  32  to supply a vaporized fuel, such as natural gas or liquefied propane (LP), to the burner  40 . A liquid fuel vaporizer (not shown, but typically a coil of tubing carrying the liquid propane to the burner  40 ) is located centrally within outer housing  30  downstream from the burner  40  to be heated by the flame and heated air from the burner  40  to evaporate the liquid propane prior to discharging it into the air flowing through the burner housing  42 . The collector  57  thus mixes the vaporized fuel with air prior to ignition of the resulting air/fuel mixture outside the burner  40 . As shown in  FIG. 8 , the vaporized fuel from the fuel line  58  is directed downwardly to the burner housing  42  behind the collector  57  and collector plate  64  and into the second portion  45  of burner housing  42 . The vaporized fuel is mixed with combustion air as it encounters the collector  57  and collector plate  64  such that an air/fuel mixture is drawn through the burner housing  42  and vented through the holes  50  and conduits  56  provided in nozzle  44 . An igniter or spark plug  66  ( FIG. 7 ) positioned downstream from the nozzle  44  ignites the air/fuel mixture discharged from the burner  40  at a location generally centered within outer housing  30 . 
     A generally conical-shaped flame diverter  70  attaches to the downstream side of the burner  40 . The flame diverter  70  includes a collar member  72  having an inner edge  70   a  near the burner and an outer edge  70   b . The flame diverter  70  defines a plurality of holes  74  ( FIG. 9 ) for admitting air to help insure that the combusting air/fuel mixture emitted from nozzle  44  has excess air for encouraging complete combustion of the fuel. Preferably, the plurality of holes  74  includes a first pattern of holes  76  near the edge  70   a  and forming, illustratively, five concentric rings with each ring defining evenly spaced and equally sized holes. The hole sizes of each ring increase with increasing distance from the edge  70   a . A second pattern of holes  80  is positioned outside the circumference of the first pattern of holes  76 . The second pattern of holes  80  defines symmetrically spaced and equally sized holes. Those skilled in the art will recognize that any pattern of holes can be used. 
     The flame diverter  70  further includes a plurality of radially spaced slats  82  ( FIGS. 11-13 ) near and generally aligned with the nozzle conduits  56  which diverge radially outwardly and angle downstream from the collar member  72  to divert the flame formed at the burner nozzle  44  outwardly toward the wall  32  of outer housing  30 . Each slat  82  has a generally trapezoidal-shaped channel  84  ( FIG. 12 ) that extends the length of the slat  82 . However, other channels shapes can be used, including but not limited to square, arcuate, rectangular, and the like. In addition, the width of the channel can vary along its length. There are no holes in the slats  82 , thereby, allowing the fuel to burn longer before entering the air flow. The outer ends of the slats  82  attach to an annular bracket or ring  86 . The slats  82  are spaced apart from each other to define a plurality of openings  90  between them through which the air moving through burner housing  42  must pass. During operation, the fan  34  moves air through the burner housing  42 . Fuel is emitted from the nozzle  44  and is ignited within the burner housing  42  to heat the air. 
     While the flame diverter  70  has been described as comprising a collar member  72  and plurality of spaced slats  82  with spaced openings  90  between the slats, it will be understood that flame diverters of other configurations may be used. For example, a flame diverter (not herein illustrated) may be a conical-shaped structure of sheet metal construction or the like having a plurality of air passage openings therein with the air passage openings being of sufficient cross-sectional area to permit air forcefully moved by fan  34  to pass through outer housing  30  without undue restriction. In addition, smaller combustion air holes, such as holes in slats, may be provided. 
     A flame cone  100  is installed within the flame diverter  70  downstream from burner nozzle  44  on the inside of the conical-shaped flame diverter  70 . ( FIGS. 6-7 ) More particularly, the flame cone  100  is preferably a cone-shaped member having a slope or conical angle generally the same as the slope of the conical-shaped flame diverter  70 . The end portion of the flame cone  100  is preferably positioned as close as possible to (even abutting) burner nozzle  44  such that a gap G ( FIG. 6 ), ranging between about 1 inch (about 2.54 cm) and about 6 inches (about 15.25 cm), and more preferably ranging between about 1½ inches (about 3.8 cm) to about 3½ inches (about 8.9 cm), is formed between the inside face of the flame diverter  70  and the outer face of the flame cone  100 . 
     In operation, the fuel line  58  delivers vaporized fuel to the burner housing  42  behind the collector  57  and collector plate  64  and into the second portion of blower/heater outer housing  30 . The vaporized fuel is mixed with combustion air as it encounters the collector  57  and collector plate  64  such that an air/fuel mixture is drawn through the blower/heater outer housing  30  with fan  34  forcefully moving air through outer housing  30  from its inlet end  36  past the burner  40  to its outlet end  38 , so that an air/fuel mixture emits from the holes  50  and conduit  56  of the nozzle  44  into the gap G between the inner face of flame diverter  70  and the outer face of the flame cone  100  where the air/fuel mixture is ignited by igniter  66 . The resulting combusting air/fuel mixture is forced by the air moving through the housing and by being forcefully ejected from the flame holes of the burner nozzle  44  to move in a divergent fashion radially outwardly and downstream within the gap G formed between the inner faces of flame diverter slats  82  and the outer face of flame cone  100 . By placing the flame cone  100  on the downstream side of the flame diverter  70  in the region of normally low pressure, the combusting air/fuel mixture is diverted from this low pressure region and is at least partially confined between the inner faces of the flame diverter  70  and the outer face of the flame cone  100  such that excess air flowing around the slats  82  is mixed with the combusting air/fuel mixture thereby resulting in substantially complete combustion of the air/fuel mixture. As a result of the flame cone  100 , substantially the entire quantity of the air/fuel mixture burns with a colorless or “blue” flame, which is visually indicative of complete (or near complete) combustion of the fuel. Of course, such substantially complete combustion maximizes the amount of heat released from the fuel such that the efficiency of the burner  40  is maximized and such that the maximum volume of air is heated the greatest amount. In addition, as the air flowing through blower/heater outer housing  30  encounters the flame diverter  70  and flame cone  100 , the air and the flames are intermixed and are forced to spread radially outwardly toward the housing walls  32 . 
     The diameter of the downstream end (i.e., the enlarged end) of flame cone  100  is such that the flame cone  100  does not unduly restrict or interfere with the flow of air through the housing. The flame cone  100  is installed in the outer housing  30  at the center thereof in close proximity to burner nozzle  44 , and in axial alignment with motor  36  such that the motor and the nozzle  44  serve to at least partially block the flow of air in the center portion of the blower/heater outer housing  30  which may in part result in the above-noted low pressure area. As the air moves past the downstream end of flame cone  100 , the air is caused to mix turbulently with the products of combustion of the fuel, to thereby more uniformly mix the heated air with the airstream moving though the housing. This results in the entire airstream exhausted from outer housing  30  being uniformly heated to a higher temperature and thus eliminates wide variations in temperature in the heated air. As shown by the exemplary charts of  FIGS. 15-18 , a larger volume of air heated uniformly to a higher temperature is available for discharge into the grain bin per unit volume of fuel consumed than when the burner is not used. 
     Changes can be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.