CA2351297A1 - Burner with venturi nozzle - Google Patents
Burner with venturi nozzle Download PDFInfo
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- CA2351297A1 CA2351297A1 CA 2351297 CA2351297A CA2351297A1 CA 2351297 A1 CA2351297 A1 CA 2351297A1 CA 2351297 CA2351297 CA 2351297 CA 2351297 A CA2351297 A CA 2351297A CA 2351297 A1 CA2351297 A1 CA 2351297A1
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- burner
- end portion
- venturi nozzle
- fuel
- plate
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Abstract
A burner that can receive fuel from a conduit and air, and can discharge a fuel/air mixture for combustion at a periphery of the burner, includes first and second plates constructed and arranged so as to form a central chamber. A plurality of burner ports extend outwardly of the chamber. A venturi nozzle includes a first inlet end portion which is disposed adjacent to the conduit and a second end portion which is spaced apart from the first end portion and disposed near the second plate.
The venturi nozzle includes an internal passageway of decreasing cross-sectional area between the first end portion and the second end portion in a direction of fuel flow. Also featured is a method of operating such a burner.
The venturi nozzle includes an internal passageway of decreasing cross-sectional area between the first end portion and the second end portion in a direction of fuel flow. Also featured is a method of operating such a burner.
Description
BURNER WITH VENTURI NOZZLE
Field of the Invention:
The present invention is directed to a burner and, in particular, to a burner including a body formed by opposing plates and a venturi nozzle adjacent to the body.
Background of the Invention:
One type of residential, light commercial water heater burner is formed of stamped sheet metal and includes two sheet metal plates or spreaders which form a chamber when the plates are fastened together. A plurality of ports extend radially outwardly from the chamber. The burner includes a central axis and the upper and lower plates include outer peripheries that are radially spaced from the central axis.
The lower plate includes an inlet opening for air and fuel to enter the chamber. A
gas conduit has an orifice that is spaced from the inlet opening of the burner. Gas from the orifice travels across the space and, along with primary air entrained by it, enters the inlet opening of the burner. This type of sheet metal burner does not employ a venturi as part of the burner. A bracket is fastened to the lower plate for securing the burner in place and for controlling the orifice distance from the plates.
Another type of water heater burner having a higher input capacity (Btuh) than a sheet metal burner is formed of cast iron. Such a burner is especially adapted for use in commercial applications. Cast iron may be more difficult to form than sheet metal and is significantly more costly. The cast iron burner includes upper and lower horizontally extending cast iron plates or spreaders which form a chamber when the plates are fastened together. A plurality of ports extend radially outwardly from the chamber. The burner includes a central axis and the upper and lower plates include outer peripheries that are radially spaced from the central axis.
The cast iron burner is different from the sheet metal burner in that it employs a cast iron, horizontally extending venturi. Also, downstream of the venturi is a mixing tube of increasing cross-sectional area in a direction of gas flow that extends horizontally and then bends upwardly and extends to the lower plate.
The sheet metal and cast iron burners have different input capacities, performance and durabilities. The cast iron burner may be more expensive to fabricate. The input capacity of a sheet metal burner is usually less than for a cast iron burner with the same port area and burner height. Using natural gas or liquified petroleum ("LP") gas, such as butane and propane, the cast iron burner has a significantly higher input range than the sheet metal burner. At high input rates, the sheet metal burner has a tendency to undesirably candle on LP gas due to low air entrainment velocity and high specific gravity of the gas. That is when fuel to the burner is shut off, unburned fuel in the burner along with fuel in the gas conduit support a yellow flame at the orifice, which leads to carbon build up at the orifice and inside the burner. Therefore, for many years water heater manufacturers have used the more costly cast iron burners rather than the sheet metal burners for higher input capacity applications.
Summary of the Invention:
In general, the present invention is directed to a burner that can receive fuel from a conduit and air, and can discharge a fuel/air mixture for combustion at a periphery of the burner. The burner includes first and second plates which are constructed and arranged relative to one another so as to form a central chamber.
A plurality of burner ports extend outwardly of the chamber. A venturi nozzle includes a first inlet end portion which is disposed adjacent to the fuel conduit and a second end portion which is spaced apart from the first end portion and disposed near the second (e.g., lower) plate. In particular, the venturi nozzle may be contiguous with the second plate. The venturi nozzle includes an internal passageway of decreasing cross-sectional area between the first and second end portions in a direction of flow. The venturi nozzle of the present invention, in view of its proximity to the second plate, advantageously causes fuel directed from the conduit to increase in velocity and decrease in pressure effective to entrain air into the venturi nozzle, which is substantially mixed only in the chamber between the plates. This enables the burner to have a high input capacity and yet be compact so as to be ideally suited for use in a water heater.
In a preferred embodiment the burner comprises the first and second plates constructed and arranged relative to one another so as to form the central chamber.
The plurality of burner ports extend outwardly of the chamber. A venturi nozzle includes a first inlet end portion which is disposed adjacent to the fuel conduit and a second end portion which is spaced apart from the first end portion and contiguous with the second plate. The venturi nozzle includes an internal passageway of decreasing cross-sectional area between the first and second end portions in the direction of flow, the cross-sectional area being at a minimum at the second end portion of the venturi nozzle.
Referring to more specific. aspects of the invention, an end portion of the second plate forms an internal passageway having an increasing cross-sectional area in the direction of flow and the second end portion of the venturi nozzle is contiguous with the end portion of the second plate. The internal passageway of the venturi nozzle may have any suitable shape and is preferably either tapered or radiused. The burner may be formed of sheet metal, which enables it to be fabricated much cheaper than cast iron burners, and yet exhibits high input capacities typically effectively attained only by cast iron burners. In use, the burner is typically oriented such that the venturi nozzle extends generally vertically and the first and second plates extend generally horizontally.
In a preferred aspect relating to the compact size and surprising high input capacity of the inventive burner, a ratio of burner diameter to venturi nozzle height ranges from about 5:1 to about ~ :1.
The venturi nozzle results in a venturi effect in the inventive burner. The jet of gas from the conduit or orifice achieves a high velocity in the "throat" of the nozzle with the resulting low pressure pulling in air around the gas jet. The air inspirited by the inventive burner is greater than in a conventional sheet metal burner. In the inventive burner the air and gas are better proportioned and mixed for improved combustion. The irnprovement in the air entrainment ability of the burner results in increased burner capacity even using spreaders or plates formed of sheet metal. The higher velocity air entrainment also provides momentum which is some cases may eliminate candling on LP gas, especially at burner extinction.
The venturi nozzle may be used without appreciably increasing the height of a conventional sheet metal burner. Typical sheet metal burners employ the mounting bracket below the lower plate which provides a space between the burner and the gas nozzle or orifice. The inventive venturi nozzle has a length which approximately fits into this space. The venturi nozzle may be formed separate from or integral with the lower plate. Another advantage is that the burner may be mounted in a water heater in a manner that is unchanged from current assembly methods. The sheet metal burner input capacity may be increased using both natural and LP gases. This enables the inventive burner to be used in higher capacity water heaters installed in larger homes, multiple dwelling apartments, commercial applications and the like. The burner may be designed to operate with low CO and low NOx emissions. The burner advantageously may eliminate the problem of candling of LP gas at the orifice on extinction which occurs when conventional sheet metal burners are attempted to be used at high input capacities.
Also, using sheet metal, the burner may be fabricated much cheaper than cast iron burners.
A method of operating a burner in accordance with the present invention comprises directing fuel from the conduit into the internal passageway of the venturi nozzle. The velocity of the fuel is increased and its pressure decreased by directing the fuel through the venturi nozzle. Air is entrained into the venturi nozzle as a result of the decreased pressure of the fuel. The fuel and entrained air from the venturi nozzle enter the chamber where substantially all of the mixing occurs.
The fuel/air mixture is discharged at the periphery of the burner and combusted.
In the preferred method the fuel and entrained air flow from second, most constricted end portion of the venturi nozzle directly into the end portion of the second plate.
Other embodiments of the invention are contemplated to provide particular features and structural variants of the basic elements. The specific embodiments referred to as well as possible variations and the various features and advantages of the invention will become better understood from the accompanying drawings together with the detailed description that follows.
Brief Descri,~tion of the Drawina~:
Figure 1 is a perspective view of a water heater with a burner constructed in accordance with the present invention;
Figure 2 is a partial, vertical cross-sectional view of the apparatus of Fig.
1;
Figure 3 is a bottom plan view of the burner of Fig. 1;
Figure 4 is a cross-sectional view of the burner as seen from the lines and arrows designated 4-4 in Fig. 3;
Figure 5 is a side elevational view of a low NOx burner constructed in accordance with the present invention having a venturi nozzle with a tapered internal passageway; and Figure 6 is a side elevational view of a low NOx burner constructed in accordance with the present invention having a venturi nozzle with a radiused internal passageway.
Detailed Description of Preferred Embodiments:
Referring now to the drawings, and to Figs. 1-4 in particular, a burner constructed according to the present invention is shown generally by reference numeral 10. The burner includes a body 12 formed by opposing plates 14, 16 and a venturi nozzle 18 disposed near the lower end of the body which enables the burner to improve its input capacity. The burner may be formed of any suitable material, for example, aluminized steel, cold rolled steel, stainless steel, ceramic or cast iron, and the plates and venturi nozzle may be formed of combinations of these materials.
The burner is used in a water heater 20 which includes a tank 21 forming an enclosure for containing water. The tank is connected to a cold water intake 22 and to an outlet pipe 24 leading to a commercial or domestic water system. The tank includes an interior wall 26, exterior wall 28 and a central exhaust flue 30, which is vented in the conventional manner. The water heater includes commercially available temperature control devices shown generally by reference numeral 32 including thermostats, thermocouples and switches. A pilot 34 produces flame for ignition of gas emitted from the periphery of the burner and is controlled in a known manner. A mounting bracket 36 is attached to the body of the burner and to a gas conduit 38 below the burner. The gas conduit includes a discharge nozzle 40 that is generally axially aligned with the burner. The burner can receive primary air and gas, and discharge an gas/air mixture at its periphery for combustion.
The body of the burner has a central axis C and comprises the upper and lower, generally circular plates 14, 16, which are constructed and arranged relative to one another so as to form a central chamber 42 (i.e., the internal region of the burner formed by the first and second plates). The upper and lower plates are fastened together as by rivets or spot welding in the known manner as shown in fig.
3. A plurality of burner ports 44 (only one of which is labeled for clarity) extend radially outwardly from the chamber (Fig. 3). Each of the upper and lower plates has an outer periphery P spaced radially from the central axis. Referring to Fig. 4, the upper and lower plates include a plurality of continuous, generally U-shaped walls 45. When the upper and lower plates are placed against each other forming the chamber, the walls 45 contact each other at abutment surfaces S and from enclosures (i.e., the ports 44).
The lower plate includes a partially frustoconical end portion 46 which forms an internal passageway 48. Ths~ internal passageway 48 has a minimum cross-sectional area at its lowermost point 50 which continually increases in a direction of flow F. The lower end portion of the lower plate includes a central opening 52.
The venturi nozzle of the burner includes upper and lower end portions 54, 56, respectively. Formed by the venturi nozzle is an internal passageway 57 which has a decreasing cross-sectional area between its lower end portion 56 and upper end portion 54 in the direction of flow. The internal passageway 57 of the venturi nozzle is aligned with the internal passageway 48 of the lower plate along the central axis C. The upper end portion of the venturi nozzle is disposed near the lower plate. In the present invention the venturi nozzle is advantageously positioned so that the component which increases in cross-sectional area immediately downstream of the venturi nozzle is the body of the burner. In particular, the upper end portion 54 of the venturi nozzle is preferably contiguous with the lower end portion 46 of the lower plate.
The body of the burner interacts directly with gas and air from the venturi nozzle such that mixing occurs primarily in the chamber 42 formed by the upper and lower plates. In preferred form, the burner is more compact, fabricated more economically and is able to achieve the advantageous effects of the invention without the use of a mixing tube of increasing cross-sectional area between the venturi nozzle and lower plate. ~fhe preferred inventive burner is quite compact in size and capable of operation at increased capacity, and is ideally suited for use in water heaters where space is limited. In this regard, a ratio of burner diameter (i.e., largest plate diameter) to venturi nozzle height ranges from about 5:1 to about 7:1.
It may be possible for a tube to be employed between the venturi nozzle and second plate so long as the tube does not increase in cross-sectional area in the direction of flow effective to function as a mixing tube and so long as the tube is not of a length which prevents the venturi effect from occurring substantially as a result of interaction between the venturi nozzle and body of the burner.
The cross-sectional area of the venturi nozzle's internal passageway 57 is preferably at a minimum at its upper end portion 62. The upper end portion of the venturi nozzle is preferably contiguous with the lower end portion of the lower plate.
The lower end portion of the lower plate includes a collar 64 forming the opening 52. The upper end portion of the venturi nozzle is sized so as to closely approximate the size of the opening 52 in the lower plate. The upper end portion of the venturi nozzle is inserted into the collar and secured in place as by tack welding or mechanically expanding the diameter of the venturi nozzle to that of the opening 52.
The bracket 36 is fastened as by rivets 37 to the lower plate. The bracket includes two upright legs 66 extending from a lower base 68. Included in the base of the bracket is a central threaded opening 70 (Fig. 3) sized to engage external threads 72 formed on the gas nozzle. Alternatively, the bracket may be fastened to the gas nozzle by some other means such as an unthreaded opening in the base of the bracket for receiving the gas conduit and wherein the bracket is screwed into place.
The venturi nozzle may have any shape of decreasing cross-sectional area.
For example, the venturi nozzle may employ a tapered internal passageway 74 as show in fig. 5. An alternate design of the venturi nozzle may employ a radiused internal passageway 76 shown in Fig. 6. The venturi nozzle may be formed separately from the lower plate. Alternatively, it may be possible to form the venturi nozzle integrally with the lower plate.
The burner may employ upper and lower plates which extend radially oufinrardly from the central axis by the same or different distances as one another.
It will be appreciated that the venturi nozzle of the burner shown in Figs. 1-4, which has upper and lower plates which extend substantially the same distance from the central axis, may include the tapered or radiused internal passageway shown in Figs. 5 and 6. The burner may employ a lower plate that extends outwardly from the central axis by a greater distance than the upper plate as shown in Figs. 5 and 6 so as to enable low NOx operation as disclosed in U.S. Patent Application Serial No.
09/565,107, entitled "Low NOx Burner," which Was filed on May 5, 2000 and is incorporated herein by reference in its entirety. The inventive burner may also be modified to include any other conventional low Nox burner features known to those skilled in the art.
The gas may be natural gas, LP gas or the like. The gas is supplied through the conduit and travels through the nozzle or orifice. The gas increases in velocity as it passes through the venturi nozzle's internal passageway and is at a highest velocity at the smallest cross-sectional area portion 62. This increase in velocity results in a decrease in pressure which entrains primary combustion air into the venturi nozzle. The gas and entrained air travel from the upper end portion of the venturi nozzle directly into the lower opening 52 of the lower plate. The partially frustoconical portion of the burner that forms an increasing cross-sectional area is disposed immediately downstream of the venturi nozzle. Substantial mixing of the gas and entrained air takes place in the chamber 42 formed by the body of the burner rather than in a mixing tube used in prior art designs. The upwardly flowing gas and entrained air travel inside the chamber of the burner and impinge upon an inner surface of a central concave portion 72 of the upper plate (Fig. 1 ), which mixes the gas and air. The resulting air/gas mixture then flows uniformly radially outwardly in all directions through the plurality of ports.
Although the invention has been described in its preferred form with a certain degree of particularity, it will be understood that the present disclosure of preferred embodiments has been made only by way of example and that various changes may be resorted to without departing from the true spirit and scope of the invention as hereafter claimed.
Field of the Invention:
The present invention is directed to a burner and, in particular, to a burner including a body formed by opposing plates and a venturi nozzle adjacent to the body.
Background of the Invention:
One type of residential, light commercial water heater burner is formed of stamped sheet metal and includes two sheet metal plates or spreaders which form a chamber when the plates are fastened together. A plurality of ports extend radially outwardly from the chamber. The burner includes a central axis and the upper and lower plates include outer peripheries that are radially spaced from the central axis.
The lower plate includes an inlet opening for air and fuel to enter the chamber. A
gas conduit has an orifice that is spaced from the inlet opening of the burner. Gas from the orifice travels across the space and, along with primary air entrained by it, enters the inlet opening of the burner. This type of sheet metal burner does not employ a venturi as part of the burner. A bracket is fastened to the lower plate for securing the burner in place and for controlling the orifice distance from the plates.
Another type of water heater burner having a higher input capacity (Btuh) than a sheet metal burner is formed of cast iron. Such a burner is especially adapted for use in commercial applications. Cast iron may be more difficult to form than sheet metal and is significantly more costly. The cast iron burner includes upper and lower horizontally extending cast iron plates or spreaders which form a chamber when the plates are fastened together. A plurality of ports extend radially outwardly from the chamber. The burner includes a central axis and the upper and lower plates include outer peripheries that are radially spaced from the central axis.
The cast iron burner is different from the sheet metal burner in that it employs a cast iron, horizontally extending venturi. Also, downstream of the venturi is a mixing tube of increasing cross-sectional area in a direction of gas flow that extends horizontally and then bends upwardly and extends to the lower plate.
The sheet metal and cast iron burners have different input capacities, performance and durabilities. The cast iron burner may be more expensive to fabricate. The input capacity of a sheet metal burner is usually less than for a cast iron burner with the same port area and burner height. Using natural gas or liquified petroleum ("LP") gas, such as butane and propane, the cast iron burner has a significantly higher input range than the sheet metal burner. At high input rates, the sheet metal burner has a tendency to undesirably candle on LP gas due to low air entrainment velocity and high specific gravity of the gas. That is when fuel to the burner is shut off, unburned fuel in the burner along with fuel in the gas conduit support a yellow flame at the orifice, which leads to carbon build up at the orifice and inside the burner. Therefore, for many years water heater manufacturers have used the more costly cast iron burners rather than the sheet metal burners for higher input capacity applications.
Summary of the Invention:
In general, the present invention is directed to a burner that can receive fuel from a conduit and air, and can discharge a fuel/air mixture for combustion at a periphery of the burner. The burner includes first and second plates which are constructed and arranged relative to one another so as to form a central chamber.
A plurality of burner ports extend outwardly of the chamber. A venturi nozzle includes a first inlet end portion which is disposed adjacent to the fuel conduit and a second end portion which is spaced apart from the first end portion and disposed near the second (e.g., lower) plate. In particular, the venturi nozzle may be contiguous with the second plate. The venturi nozzle includes an internal passageway of decreasing cross-sectional area between the first and second end portions in a direction of flow. The venturi nozzle of the present invention, in view of its proximity to the second plate, advantageously causes fuel directed from the conduit to increase in velocity and decrease in pressure effective to entrain air into the venturi nozzle, which is substantially mixed only in the chamber between the plates. This enables the burner to have a high input capacity and yet be compact so as to be ideally suited for use in a water heater.
In a preferred embodiment the burner comprises the first and second plates constructed and arranged relative to one another so as to form the central chamber.
The plurality of burner ports extend outwardly of the chamber. A venturi nozzle includes a first inlet end portion which is disposed adjacent to the fuel conduit and a second end portion which is spaced apart from the first end portion and contiguous with the second plate. The venturi nozzle includes an internal passageway of decreasing cross-sectional area between the first and second end portions in the direction of flow, the cross-sectional area being at a minimum at the second end portion of the venturi nozzle.
Referring to more specific. aspects of the invention, an end portion of the second plate forms an internal passageway having an increasing cross-sectional area in the direction of flow and the second end portion of the venturi nozzle is contiguous with the end portion of the second plate. The internal passageway of the venturi nozzle may have any suitable shape and is preferably either tapered or radiused. The burner may be formed of sheet metal, which enables it to be fabricated much cheaper than cast iron burners, and yet exhibits high input capacities typically effectively attained only by cast iron burners. In use, the burner is typically oriented such that the venturi nozzle extends generally vertically and the first and second plates extend generally horizontally.
In a preferred aspect relating to the compact size and surprising high input capacity of the inventive burner, a ratio of burner diameter to venturi nozzle height ranges from about 5:1 to about ~ :1.
The venturi nozzle results in a venturi effect in the inventive burner. The jet of gas from the conduit or orifice achieves a high velocity in the "throat" of the nozzle with the resulting low pressure pulling in air around the gas jet. The air inspirited by the inventive burner is greater than in a conventional sheet metal burner. In the inventive burner the air and gas are better proportioned and mixed for improved combustion. The irnprovement in the air entrainment ability of the burner results in increased burner capacity even using spreaders or plates formed of sheet metal. The higher velocity air entrainment also provides momentum which is some cases may eliminate candling on LP gas, especially at burner extinction.
The venturi nozzle may be used without appreciably increasing the height of a conventional sheet metal burner. Typical sheet metal burners employ the mounting bracket below the lower plate which provides a space between the burner and the gas nozzle or orifice. The inventive venturi nozzle has a length which approximately fits into this space. The venturi nozzle may be formed separate from or integral with the lower plate. Another advantage is that the burner may be mounted in a water heater in a manner that is unchanged from current assembly methods. The sheet metal burner input capacity may be increased using both natural and LP gases. This enables the inventive burner to be used in higher capacity water heaters installed in larger homes, multiple dwelling apartments, commercial applications and the like. The burner may be designed to operate with low CO and low NOx emissions. The burner advantageously may eliminate the problem of candling of LP gas at the orifice on extinction which occurs when conventional sheet metal burners are attempted to be used at high input capacities.
Also, using sheet metal, the burner may be fabricated much cheaper than cast iron burners.
A method of operating a burner in accordance with the present invention comprises directing fuel from the conduit into the internal passageway of the venturi nozzle. The velocity of the fuel is increased and its pressure decreased by directing the fuel through the venturi nozzle. Air is entrained into the venturi nozzle as a result of the decreased pressure of the fuel. The fuel and entrained air from the venturi nozzle enter the chamber where substantially all of the mixing occurs.
The fuel/air mixture is discharged at the periphery of the burner and combusted.
In the preferred method the fuel and entrained air flow from second, most constricted end portion of the venturi nozzle directly into the end portion of the second plate.
Other embodiments of the invention are contemplated to provide particular features and structural variants of the basic elements. The specific embodiments referred to as well as possible variations and the various features and advantages of the invention will become better understood from the accompanying drawings together with the detailed description that follows.
Brief Descri,~tion of the Drawina~:
Figure 1 is a perspective view of a water heater with a burner constructed in accordance with the present invention;
Figure 2 is a partial, vertical cross-sectional view of the apparatus of Fig.
1;
Figure 3 is a bottom plan view of the burner of Fig. 1;
Figure 4 is a cross-sectional view of the burner as seen from the lines and arrows designated 4-4 in Fig. 3;
Figure 5 is a side elevational view of a low NOx burner constructed in accordance with the present invention having a venturi nozzle with a tapered internal passageway; and Figure 6 is a side elevational view of a low NOx burner constructed in accordance with the present invention having a venturi nozzle with a radiused internal passageway.
Detailed Description of Preferred Embodiments:
Referring now to the drawings, and to Figs. 1-4 in particular, a burner constructed according to the present invention is shown generally by reference numeral 10. The burner includes a body 12 formed by opposing plates 14, 16 and a venturi nozzle 18 disposed near the lower end of the body which enables the burner to improve its input capacity. The burner may be formed of any suitable material, for example, aluminized steel, cold rolled steel, stainless steel, ceramic or cast iron, and the plates and venturi nozzle may be formed of combinations of these materials.
The burner is used in a water heater 20 which includes a tank 21 forming an enclosure for containing water. The tank is connected to a cold water intake 22 and to an outlet pipe 24 leading to a commercial or domestic water system. The tank includes an interior wall 26, exterior wall 28 and a central exhaust flue 30, which is vented in the conventional manner. The water heater includes commercially available temperature control devices shown generally by reference numeral 32 including thermostats, thermocouples and switches. A pilot 34 produces flame for ignition of gas emitted from the periphery of the burner and is controlled in a known manner. A mounting bracket 36 is attached to the body of the burner and to a gas conduit 38 below the burner. The gas conduit includes a discharge nozzle 40 that is generally axially aligned with the burner. The burner can receive primary air and gas, and discharge an gas/air mixture at its periphery for combustion.
The body of the burner has a central axis C and comprises the upper and lower, generally circular plates 14, 16, which are constructed and arranged relative to one another so as to form a central chamber 42 (i.e., the internal region of the burner formed by the first and second plates). The upper and lower plates are fastened together as by rivets or spot welding in the known manner as shown in fig.
3. A plurality of burner ports 44 (only one of which is labeled for clarity) extend radially outwardly from the chamber (Fig. 3). Each of the upper and lower plates has an outer periphery P spaced radially from the central axis. Referring to Fig. 4, the upper and lower plates include a plurality of continuous, generally U-shaped walls 45. When the upper and lower plates are placed against each other forming the chamber, the walls 45 contact each other at abutment surfaces S and from enclosures (i.e., the ports 44).
The lower plate includes a partially frustoconical end portion 46 which forms an internal passageway 48. Ths~ internal passageway 48 has a minimum cross-sectional area at its lowermost point 50 which continually increases in a direction of flow F. The lower end portion of the lower plate includes a central opening 52.
The venturi nozzle of the burner includes upper and lower end portions 54, 56, respectively. Formed by the venturi nozzle is an internal passageway 57 which has a decreasing cross-sectional area between its lower end portion 56 and upper end portion 54 in the direction of flow. The internal passageway 57 of the venturi nozzle is aligned with the internal passageway 48 of the lower plate along the central axis C. The upper end portion of the venturi nozzle is disposed near the lower plate. In the present invention the venturi nozzle is advantageously positioned so that the component which increases in cross-sectional area immediately downstream of the venturi nozzle is the body of the burner. In particular, the upper end portion 54 of the venturi nozzle is preferably contiguous with the lower end portion 46 of the lower plate.
The body of the burner interacts directly with gas and air from the venturi nozzle such that mixing occurs primarily in the chamber 42 formed by the upper and lower plates. In preferred form, the burner is more compact, fabricated more economically and is able to achieve the advantageous effects of the invention without the use of a mixing tube of increasing cross-sectional area between the venturi nozzle and lower plate. ~fhe preferred inventive burner is quite compact in size and capable of operation at increased capacity, and is ideally suited for use in water heaters where space is limited. In this regard, a ratio of burner diameter (i.e., largest plate diameter) to venturi nozzle height ranges from about 5:1 to about 7:1.
It may be possible for a tube to be employed between the venturi nozzle and second plate so long as the tube does not increase in cross-sectional area in the direction of flow effective to function as a mixing tube and so long as the tube is not of a length which prevents the venturi effect from occurring substantially as a result of interaction between the venturi nozzle and body of the burner.
The cross-sectional area of the venturi nozzle's internal passageway 57 is preferably at a minimum at its upper end portion 62. The upper end portion of the venturi nozzle is preferably contiguous with the lower end portion of the lower plate.
The lower end portion of the lower plate includes a collar 64 forming the opening 52. The upper end portion of the venturi nozzle is sized so as to closely approximate the size of the opening 52 in the lower plate. The upper end portion of the venturi nozzle is inserted into the collar and secured in place as by tack welding or mechanically expanding the diameter of the venturi nozzle to that of the opening 52.
The bracket 36 is fastened as by rivets 37 to the lower plate. The bracket includes two upright legs 66 extending from a lower base 68. Included in the base of the bracket is a central threaded opening 70 (Fig. 3) sized to engage external threads 72 formed on the gas nozzle. Alternatively, the bracket may be fastened to the gas nozzle by some other means such as an unthreaded opening in the base of the bracket for receiving the gas conduit and wherein the bracket is screwed into place.
The venturi nozzle may have any shape of decreasing cross-sectional area.
For example, the venturi nozzle may employ a tapered internal passageway 74 as show in fig. 5. An alternate design of the venturi nozzle may employ a radiused internal passageway 76 shown in Fig. 6. The venturi nozzle may be formed separately from the lower plate. Alternatively, it may be possible to form the venturi nozzle integrally with the lower plate.
The burner may employ upper and lower plates which extend radially oufinrardly from the central axis by the same or different distances as one another.
It will be appreciated that the venturi nozzle of the burner shown in Figs. 1-4, which has upper and lower plates which extend substantially the same distance from the central axis, may include the tapered or radiused internal passageway shown in Figs. 5 and 6. The burner may employ a lower plate that extends outwardly from the central axis by a greater distance than the upper plate as shown in Figs. 5 and 6 so as to enable low NOx operation as disclosed in U.S. Patent Application Serial No.
09/565,107, entitled "Low NOx Burner," which Was filed on May 5, 2000 and is incorporated herein by reference in its entirety. The inventive burner may also be modified to include any other conventional low Nox burner features known to those skilled in the art.
The gas may be natural gas, LP gas or the like. The gas is supplied through the conduit and travels through the nozzle or orifice. The gas increases in velocity as it passes through the venturi nozzle's internal passageway and is at a highest velocity at the smallest cross-sectional area portion 62. This increase in velocity results in a decrease in pressure which entrains primary combustion air into the venturi nozzle. The gas and entrained air travel from the upper end portion of the venturi nozzle directly into the lower opening 52 of the lower plate. The partially frustoconical portion of the burner that forms an increasing cross-sectional area is disposed immediately downstream of the venturi nozzle. Substantial mixing of the gas and entrained air takes place in the chamber 42 formed by the body of the burner rather than in a mixing tube used in prior art designs. The upwardly flowing gas and entrained air travel inside the chamber of the burner and impinge upon an inner surface of a central concave portion 72 of the upper plate (Fig. 1 ), which mixes the gas and air. The resulting air/gas mixture then flows uniformly radially outwardly in all directions through the plurality of ports.
Although the invention has been described in its preferred form with a certain degree of particularity, it will be understood that the present disclosure of preferred embodiments has been made only by way of example and that various changes may be resorted to without departing from the true spirit and scope of the invention as hereafter claimed.
Claims (18)
1. A burner that can receive fuel from a conduit and air, and can discharge a fuel/air mixture for combustion at a periphery of said burner, comprising:
first and second plates constructed and arranged relative to one another so as to form a central chamber, a plurality of burner ports extending outwardly of said chamber, and a venturi nozzle including a first inlet end portion which is disposed adjacent to the conduit and a second end portion which is spaced apart from said first end portion and disposed near said second plate, wherein said venturi nozzle includes an internal passageway of decreasing cross-sectional area between said first end portion and said second end portion in a direction of fuel flow.
first and second plates constructed and arranged relative to one another so as to form a central chamber, a plurality of burner ports extending outwardly of said chamber, and a venturi nozzle including a first inlet end portion which is disposed adjacent to the conduit and a second end portion which is spaced apart from said first end portion and disposed near said second plate, wherein said venturi nozzle includes an internal passageway of decreasing cross-sectional area between said first end portion and said second end portion in a direction of fuel flow.
2. The burner of claim 1 wherein said burner is formed of sheet metal.
3. The burner of claim 1 wherein said internal passageway is tapered.
4. The burner of claim 1 wherein said internal passageway is radiused.
5. The burner of claim 1 wherein said second plate is disposed below said first plate.
6. The burner of claim 1 wherein said venturi nozzle extends generally vertically and said first and second plates extend generally horizontally.
7. The burner of claim 1 wherein said second end portion of said venturi nozzle is contiguous with said second plate.
8. The burner of claim 5 wherein said second plate extends from the central axis by a greater distance than said first plate.
9. The burner of claim 1 wherein a ratio of a diameter of said burner to a height of said venturi nozzle ranges from about 5:1 to about 7:1.
10. A burner that can receive fuel from a conduit and air, and can discharge a fuel/air mixture for combustion at a periphery of said burner, comprising:
first and second plates constructed and arranged relative to one another so as to form a central chamber, a plurality of burner ports extending outwardly of said chamber, and a venturi nozzle including a first inlet end portion which is disposed adjacent to the conduit and a second end portion which is spaced apart from said first end portion and contiguous with said second plate, wherein said venturi nozzle includes an internal passageway of decreasing cross-sectional area between said first end portion and said second end portion in a direction of fuel flow, said cross-sectional area being at a minimum at said second end portion.
first and second plates constructed and arranged relative to one another so as to form a central chamber, a plurality of burner ports extending outwardly of said chamber, and a venturi nozzle including a first inlet end portion which is disposed adjacent to the conduit and a second end portion which is spaced apart from said first end portion and contiguous with said second plate, wherein said venturi nozzle includes an internal passageway of decreasing cross-sectional area between said first end portion and said second end portion in a direction of fuel flow, said cross-sectional area being at a minimum at said second end portion.
11. The burner of claim 10 wherein an end portion of said second plate forms an internal passageway having an increasing cross-sectional area in the direction of flow and said second end portion of said venturi nozzle is contiguous with said end portion of said second plate.
12. The burner of claim 10 wherein said burner is formed of sheet metal.
13. The burner of claim 10 wherein said internal passageway is tapered along substantially an entire length of said venturi nozzle.
14. The burner of claim 10 wherein said internal passageway is radiused along substantially an entire length of said venturi nozzle.
15. The burner of claim 10 wherein said second plate is disposed below said first plate.
16. The burner of claim 10 wherein said venturi nozzle extends generally vertically and said first and second plates extend generally horizontally.
17. A method of operating a burner comprising first and second plates constructed and arranged relative to one another so as to form a central chamber, a plurality of burner ports extending outwardly of said chamber, and a venturi nozzle including a first inlet end portion which is disposed adjacent to a fuel conduit and a second end portion which is spaced apart from said first end portion and disposed near said second plate, wherein said venturi nozzle includes an internal passageway of decreasing cross-sectional area between said first end portion and said second end portion in a direction of flow, said method comprising directing fuel from said conduit into said internal passageway of said venturi nozzle in the direction of flow, increasing velocity and decreasing pressure of said fuel by directing said fuel through said venturi nozzle, entraining air into said venturi nozzle as a result of the decreasing pressure of said fuel, directing said fuel and entrained air from said venturi nozzle into said chamber, mixing said gas and said entrained air substantially completely in said chamber, discharging a fuel/air mixture at the periphery of said burner, and combusting said discharged fuel/air mixture.
18. The method of claim 17 said second end portion of said venturi nozzle being contiguous with an end portion of said second plate that has an internal passageway with an increasing cross-sectional area in the direction of flow, wherein said fuel and said entrained air flow from the second end portion of said venturi nozzle directly into said internal passageway of said end portion of said second plate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US64442600A | 2000-08-23 | 2000-08-23 | |
| US09/644,426 | 2000-08-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2351297A1 true CA2351297A1 (en) | 2002-02-23 |
Family
ID=24584849
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2351297 Abandoned CA2351297A1 (en) | 2000-08-23 | 2001-06-26 | Burner with venturi nozzle |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2351297A1 (en) |
-
2001
- 2001-06-26 CA CA 2351297 patent/CA2351297A1/en not_active Abandoned
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