WO2014028348A2

WO2014028348A2 - Low cost radial gas-burner

Info

Publication number: WO2014028348A2
Application number: PCT/US2013/054442
Authority: WO
Inventors: Daniel Mark ST. LOUIS
Original assignee: Dk Innovations, Inc.
Priority date: 2012-08-13
Filing date: 2013-08-10
Publication date: 2014-02-20
Also published as: WO2014028348A3; US20150276218A1

Abstract

A Low Cost Radial Gas Burner (LCRGB) burner comprises a gas turbulator means, at least one means for producing an ambient-air-inducing jet of the gaseous fuel to create a self-sustaining combustible fuel-air mixture, and a combustion initiation means located at a combustion initiation position proximate the gas turbulator means. The gas turbulator means has a planar surface. The jet of gaseous fuel is directed towards the planar surface to envelope the gas turbulator means and is ignited by the combustion initiation means. The gas turbulator means may be configured as a planar rotor having a flow deflector and turbine vanes. In yet another embodiment of the LCRGB, there are at least two jets of the gaseous fuel which are directed to the planar surface of the gas turbulator means.

Description

Non-Provisional Patent Application

Of

Daniel Mark St. Louis

(Wichita, Kansas, U.S.A.)

For

Low Cost Radial Gas-Burner

Related Applications :

This application claims priority from U.S. Provisional Patent Application No. 61/682,573 filed on August 13, 2012.

Field of the Invention:

The present invention relates to low-heat capacity gas burners for use in domestic, industrial, and commercial

applications .

Background:

Most low-heat capacity burners (having heat-output in the range of 500 to 400 , 000_BTUH) are the Venturi Driven and Fan Assisted Premix Burner (referred to herein as "Premix" Burner) type. Premix burners typically have a venturi as part of the burner design. The purpose of the venturi is to provide good mixing of the correct proportions of fuel and air, and to use the momentum of the gaseous fuel to direct the flame as required. Premix burners are commonly used in propane torches, home furnaces, home hot water heaters, gas stoves, and other domestic and commercial appliances. The premix burner that is used in domestic tank-type water heaters is a special case of a premix burner in that the jet of gas impinges on a lower plate that redirects the flow of gaseous fuel radially after which the flow enters a radial design venturi . The air and fuel emerge from the venturi to combust and create a radial flame pattern. Because of its size and shape, the home hot water heater burner is commonly known in the industry as a "pancake burner".

Pancake burners are relatively inexpensive to produce, but in the highly competitive market of domestic hot water heaters any significant cost savings to the burner would be of great

importance, especially considering that many millions of hot water heaters which use pancake burners are sold every year.

A recent development in domestic water heaters is the

tankless water. This uses a premix burner which is configured to produce a line of flame jets. The flame jets heat the water which flows in a finned heat exchanger to rapidly heat the water as demanded. These premix burners, referred to herein as "sandwich" burners, are produced by peripherally unitizing two stamped plates. The sandwich burners therefore are more complicated to design and manufacture than the pancake burners described above.

The pancake and sandwich burners are typically formed by blanking, stamping and punching relatively large steel plates. The stamping dies are very expensive and the stamping operations require very capital intensive specialized equipment. The complex stampings are necessary so that when two plates are assembled together, they form the necessary radial or linear venturi. Another application of the Low Cost Radial Gas Burner is as an economical replacement for linear burners such as those found in most home furnaces and in most torches. These linear burners produce a very long and narrow flame. In some applications, a long narrow flame is not economical or practical and a pancake burner is not practical either as it will not provide the correct flame coverage. An array of Low Cost Radial Gas Burners is contemplated to be an economical substitution for linear burners in such applications .

Thus, what is needed is a simple and economical gaseous fuel burner that can be manufactured at a lower cost and can also provide better flame coverage than pancake and sandwich burners.

Summary :

A Low Cost Radial Gas Burner (LCRGB) burner for combusting a gaseous fuel is disclosed. The burner comprises a gas turbulator means, at least one means for producing an ambient-air-inducing jet of the gaseous fuel to create a combustible fuel-air mixture and a combustion initiation means located at a combustion

initiation position proximate the gas turbulator means. The jet of gaseous fuel is directed towards and envelopes the gas turbulator means and is ignited by the combustion initiation means. The gas turbulator means has a planar surface and the jet of the gaseous fuel is directed at the planar surface.

In one embodiment of the LCRGB, the gas turbulator means is configured as a planar rotor having flow deflector and turbine vanes. The flow of the air-fuel mixture past the turbine vanes causes the rotor to spin and further mix the air and fuel in the air-fuel mixture.

In another embodiment of the LCRGB, a spin inducing means such as an electric or a fluidic motor is coupled to the rotor to spin the rotor and further mix the air and fuel in the air-fuel mixture .

In yet another embodiment of the LCRGB, there are at least two jets of the gaseous fuel which are directed to the planar surface of the gas turbulator means.

In yet another embodiment of the LCRGB, the jet of gaseous fuel is directed to an upper surface of the turbulator.

Brief Description of the Drawings :

FIG.1A is an isometric representation of a first embodiment of the Low Cost Radial Gas Burner 10 described herein.

FIG. IB is an elevation view cross-sectional representation of the Low Cost Radial Gas Burner 10 described herein in operation. The burner element 10 is being supplied with a gaseous fuel through a gas supply pipe. The flames propagate radially across turbulator disk lOd.

FIG.1C is an elevation view cross-sectional representation of the Low Cost Radial Gas Burner 10 described herein showing the major components of the burner.

FIG. ID is an elevation view cross-sectional representation of the Low Cost Radial Gas Burner 10 described herein wherein disk lOd is supported independently of the gaseous fuel ejector 10η.

FIG.2 is a plan view cross-sectional representation of the Low Cost Radial Gas Burner 10 of FIG. 1C.

FIG.3 is another plan view cross-sectional representation of the Low Cost Radial Gas Burner 10 of FIG. 1C. FIG.4 is an elevation view cross-sectional representation of a second embodiment of the Low Cost Radial Gas Burner 10 described herein wherein the gas ejector is located at an elevated position relative to the gas supply pipe.

FIG.5 is an elevation view cross-sectional representation of a third embodiment of the Low Cost Radial Gas Burner 10 described herein wherein an air eductor is provided around the gas ejector to control the amount of ambient air that can be induced into the gaseous fuel jet stream.

FIG.6 is a plan view cross-sectional representation of the Low Cost Radial Gas Burner 10 of FIG. 5.

FIG.7 is an isometric representation of a fourth embodiment of the Low Cost Radial Gas Burner described herein.

FIG.8A is another isometric representation of the turbulator disk of FIG. 7.

FIG.8B is a plan view cross-sectional representation of the turbulator disk of FIG. 7.

FIG.9A is a elevation view cross-sectional representation of the sandwich burner according to the prior art.

FIG.9B is an elevation view cross-sectional representation of a row of LCRGBs 10 that can be substituted for the sandwich burner of FIG. 9A.

FIG.10A is an isometric representation of another embodiment of the LCRGB wherein the jet of gaseous fuel is directed to an upper surface of the turbulator disk.

FIG.10B is an elevation view cross-sectional representation of the LCRGB of FIG.10A.

FIG. IOC is an elevation view cross-sectional representation of the LCRGB of FIG.10A which uses a deflector disk to direct the gaseous fuel to the upper surface of the turbulator disk.

Description of the Invention :

This application discloses a low cost radial gas burner element which is simple in construction and relatively inexpensive to mass-produce. This burner element can be used in residential appliances such as cooking ranges, hot water heaters, home

furnaces, home tankless or tank type hot water heaters, gas stoves, and other domestic appliances. The burner element also finds applications in commercial and industrial appliances such as central heating furnaces, hot water heaters or boilers, industrial dryers, and other equipment. The Low Cost Radial Gas Burner element described herein (which will be commercially marketed as a "micro disk burner") is a very simple and economical alternative to conventional pancake and sandwich burners.

The Low Cost Radial Gas Burner simply consists of a gas jet that impinges on a small disk or plate. It was discovered through experimentation that this very simple arrangement creates a very good burner that is clean burning and has a very desirable flame shape and very optimal flame coverage for some applications. The design of the burner is based on scientific principles used in HVAC engineering and air handling equipment design. These

principles state that changes of direction of airflow produce turbulence and mixing. These principles have been applied to the LCRGB described herein and the result is that the need for a venturi in order to provide a good burner flame has been

eliminated .

In operation, the gas jet impinges on a turbulator on which the gas jet is redirected along the surface of the turbulator. The turbulator can be in the form of a disk or a square plate or rectangular plate or a ribbon or any other shape which has a planar surface. When the gas jet is redirected on the planar surface of the turbulator, the turbulence from the change of direction helps entrain and mix ambient air into the stream of gaseous fuel. Thus, enough air is entrained into the gas jet in a very short distance along the planar surface to provide a self- sustaining combustible fuel-air mixture. Still further mixing is attained as the fuel and air exit the circumference of the micro^¬ disk. Fluid dynamics forces try to keep the flow attached to the disk. However, the sharp discontinuity at the edge of the disk makes this impossible. The result is a zone of toroidal flow all around the circumference of the disk. This toroidal flow produces intense mixing and also creates a mechanism for producing a stable flame. The proportion of air and gaseous fuel in the resulting air-fuel mixture is sufficient to support sustained combustion. The air and gaseous fuel are thoroughly mixed and the mixture produces a very good flame and efficient combustion.

FIGs. 1A, IB, 1C, 2, and 3 are various representations of the Low Cost Radial Gas Burner 10 described herein. Low Cost Radial Gas Burner 10 comprises a floor member lOf which supports a fuel gas supply pipe lOp. Pipe lOp is connected to a fuel ejector or nipple 10η which has an outlet orifice lOno through which the gaseous fuel exits as a jet stream into the ambient air. Low Cost Radial Gas Burner 10 further comprises a turbulator which is configured as disk lOd on which the gas jet impinges during operation. Disk lOd is supported at a required distance from the nipple orifice lOno by supports 10s which are connected to floor member lOf. Turbulator disk lOd can be made of a suitable metal or a suitable ceramic or any other high-temperature resistant material. Supports 10s can be thin steel rods which are rigid enough to support the weight of disk lOd. Supports 10s can be attached to floor member lOf and disk lOd by welding or mechanical attachments such as hooks or any other means that will be obvious to persons having ordinary skill in the mechanical arts.

As shown in FIG. IB, a gaseous fuel at a relatively higher pressure than ambient is supplied to burner pipe lOp. The gaseous fuel exits as a high-velocity jet through nipple orifice lOno. A simple hole drilled in a pipe or tube may be sufficient to

function as nipple orifice lOno. As the gaseous fuel moves through the ambient air, it induces ambient air into the jet stream to form a self-sustaining combustible gaseous fuel-air mixture. The gaseous fuel-air mixture impinges upon the lower face lOdf of disc lOd resulting in localized turbulence which further mixes the gaseous fuel with the entrained and surrounding ambient air. The turbulent fuel-air mixture is capable of sustaining combustion and can be ignited by a combustion initiation means (CIM) lOz. CIM lOz could be any means of igniting a flame such as a standard spark igniter or a pilot flame or a glowbar or a burning matchstick or even a hot ember.

As mentioned previously, the flame produced by this simple, inexpensive burner is comparable to the flame produced by the more complicated and expensive pancake burner. The Low Cost Radial Gas Burner provides flame coverage that is comparable to the flame produced by the pancake burner. Further, CO and NOx levels of the Low Cost Radial Gas Burner are comparable to those of the pancake burner. Cost-wise, it is estimated that the Low Cost Radial Gas Burner could be produced at a fraction of the cost of the pancake burner .

FIG. 4 is a vertical cross-sectional representation of the Low Cost Radial Gas Burner 10 wherein the gas ejector 10η is elevated from the floor member lOf. This embodiment can be used wherein it is desirable to have the flame in a somewhat remote location. The constructional and operational details of the second embodiment of Low Cost Radial Gas Burner 10 are similar to those of the first embodiment of the Low Cost Radial Gas Burner shown in FIG. 1C.

FIGs. 5 and 6 show vertical and plan view cross-sectional representations of a third embodiment of the Low Cost Radial Gas Burner 10 wherein an eductor lOe is located around gas ejector 10η. Eductor lOe has air supply orifices lOeo through which air is induced into the gaseous fuel jet stream. By controlling the size of orifices lOeo, the amount of air that is induced into the gaseous fuel jet stream can be controlled. This embodiment can be used in applications which require a finer control of the air-fuel ratio used in the burner. The constructional and operational details of the third embodiment of Low Cost Radial Gas Burner 10 are similar to those of the first embodiment of the Low Cost

Radial Gas Burner shown in FIG. 1C except that air is drawn into the gaseous fuel jet stream through eductor orifices lOeo.

From the above description it is quite obvious that the micro disk burner is a very simple design that uses a fraction of the material and manufacturing costs compared to a pancake burner. The micro disk burner can be produced economically by most sheet metal shops with very standard and simple tooling. The savings in material and in forming result in a burner that is substantially less expensive than a standard pancake burner which is currently used in most appliances.

It will be quite obvious that there is no true limit to how small or large turbulator disk lOd can be to operate properly. The applicant has successfully operated micro-disk burners which have turbulator disks which were half-inch in diameter to many inches in diameter. These dimensional ranges are not limiting and smaller or larger simple micro disk burners may have applications.

A one and one half-inch disk was tested as a direct

replacement for a pancake burner in a conventional domestic hot water heater. The results were that the micro disk equaled or outperformed the pancake disk in all regards at a fraction of the cost. When fired in open air, the flame diameter of the micro disk is smaller than that of the pancake burner. However, in the air flow environment created by the combustion chamber of the

conventional domestic hot water heater, the micro disk burner produces a nearly identical sized and shaped flame as the pancake burner. Thus the micro disk burner produces the same heating characteristics as a pancake burner but at a lower cost.

It will be quite obvious that the micro disk burner is not limited to operation with natural gas but it can be designed to operate with any common gaseous fuel such as butane or propane.

It will be quite obvious also that the micro disk burner design is not limited to turbulators which are configured as round cross section disks. Other shapes such as a square plate or a star or a toothed wheel cross-sectioned plate can be used for the turbulator. As another example, a disk with holes proximate to its periphery could be used as the turbulator. These modifications to the disk would further enhance flame turbulence resulting in more complete combustion. Further, these shapes may be useful in further enhancing or modifying the shape of the flame.

The micro disk burner can create a short and relatively constant flame front. This "wall of fire" is ideal for heating a surface such as a pot or pan when used to replace the common gas burner on a domestic or commercial stove. Further, by heating from the center of the pot or pan, more heat transfer can be expected to the cooking utensil resulting in greater energy efficiency.

Operating several micro disk burners in an array can further expand the "wall of fire" concept. This larger wall of fire would be well suited for evenly heating a larger object such as a heat exchanger. One practical example would be to provide heat to the heat exchanger in a gas fired tankless water heater. Currently these water heaters use a very large array of linear venturi burners. These linear venturi burners create a long narrow flame and have the following disadvantage in this application: (a) The heating is not inherently even, (b) a very large number of

individual burners/flames are required in an attempt to achieve more even heating of the heat exchanger, (c) the large number of individual burners is costly, and (d) the long flames necessitates a tall combustion chamber which increases cost and restricts the installation space for the heater.

Alternately, the tankless water heater may use a sandwich burner. The general representation of a sandwich burner used in some conventional water heaters is shown in FIG.9A. As shown in FIG.9A, sandwich burners of the prior art are fabricated by peripherally unitizing two plates which were previously stamped to create the complex venturi flow channels there between. It will be obvious from FIG.9A, that the manufacturing processes to create these plates and unitize them to form the sandwich burner are complicated and expensive. The sandwich burner can be economically replaced by a row of LCRGBs 10, as shown in FIG.9B, resulting in a lower cost tankless water heater.

To further reduce costs, as shown in FIG.9B, the individual turbulator disks may be aggregated as a single strip on which multiple gaseous fuel jets impinge. Thus a long strip of flame (instead of multiple individual flames) will be produced which will provide more efficient heat transfer in a smaller space. The single strip can be a plain rectangular strip or a toothed

rectangular strip or any other complex shape which may be useful in further enhancing or modifying the shape of the flame.

Still further modifications such as bumps, bent edges, waves, perturbations, holes, curvatures, geometric, and non-geometric cross sections may be provided on the turbulator disk or strip for specific burner applications. These changes and others may be implemented without departing from the spirit of this invention.

It will be obvious to one of ordinary skill in the art that there are countless variations which may possibly be used for producing the Low Cost Radial Gas Burner described herein.

For example, the gaseous fuel ejector 10η and turbulator disk lOd do not need to be an integral unit to form the Low Cost Radial Gas Burner. As shown in FIG. ID, they may be supported separately while maintaining the relative location of the gaseous fuel jet ejector 10η and disk lOd. Thus ejector 10η and disk lOd cooperate to function as the burner. For example, the disk lOd could be installed inside a domestic water heater supported from the central baffle plate or other convenient structure, separately from ejector 10η. But they would work together to function as a Low Cost Radial Gas Burner. Yet further as shown in FIGs.7, 8A, and 8B with respect to the fourth embodiment of Low Cost Radial Gas Burner 20, turbulator disk 20d may be integrated into a mechanical mixer. Such an arrangement was tested and found to provide very thorough mixing in a very small space. Disk 20d is configured as a rotor with flow deflector 20dz and turbine vanes 20dv which spins around center 20dc. Disk 20d can be self-spinning being motivated by the flow of the air-fuel mixture past vanes 20dv. Alternately, it can be spun by an external rotating device such as an electric or fluidic motor 20dm as shown in FIG.7. Disk 20d can also double as a fan as well as a micro disk enhanced air/fuel rotary mixer.

The above embodiments of the LCRGB 10 have the gaseous fuel directed to the lower surface of turbulator disk lOd. However, as shown in FIGS. 10A, 10B, and IOC, the gaseous fuel could also be directed to the upper surface of the turbulator disk. Such an arrangement would provide the added benefit of cooling the

turbulator disk to avoid overheating of the burner. The cooling of the burner could be very important, especially for higher

capacity burner applications and in higher temperature burner environments. Additionally, this embodiment will likely re- entrain products of combustion and may have an effect on

combustion similar to flue gas recirculation resulting in low NOx production by the burner.

In the embodiment of LCRGB 10 of FIG. 10A, fuel gas inlet pipe lOpe passes through turbulator disk lOw which is shaped as a washer. A fuel deflecting cap 10c is positioned over outlet lOno of nipple 10η of fuel pipe lOpe to deflect the fuel 180 degrees to impinge upper surface lOwu of turbulator disk lOw. As described previously, the jets of gaseous fuel entrain ambient air to provide a self-sustaining combustible mixture of fuel and air which is then ignited by CIM lOz.

A variation of the above described embodiment is shown in FIG. IOC, wherein outlet lOno of nipple 10η is located relatively close and generally parallel to upper surface lOwu of washer shaped turbulator disk lOw. A deflecting disk lOg is located relatively close to outlet lOno of nipple 10η to deflect the gaseous fuel 90 degrees over upper surface lOwu of disk lOw. As described previously, the jets of gaseous fuel passing over surface lOwu of disk lOw entrain ambient air to provide a self- sustaining combustible mixture of fuel and air which is then ignited by CIM lOz .

It will be obvious to persons skilled in the art that other raw materials in different proportions could be substituted for those disclosed above to make the Low Cost Radial Gas Burner element described above without departing from the spirit of the invention .

All of these modifications to the above-described Low Cost Radial Gas Burner are considered to fall within the scope of the present invention.

Claims

Claims :

I claim:

1) A burner for combusting a gaseous fuel, the burner comprising :

a gas turbulator means;

at least one means for producing an ambient-air-inducing jet of the gaseous fuel to create a combustible fuel-air mixture, the jet being directed towards and enveloping the gas turbulator means; and

a combustion initiation means located at a combustion initiation position proximate the gas turbulator means to initiate the combustion of the fuel-air mixture around the gas turbulator means.

2) The burner of claim 1 wherein the gas turbulator means has a planar surface and the jet of the gaseous fuel is directed at the planar surface.

3) The burner of claim 1 wherein the gas turbulator means is configured as a planar rotor.

4) The burner of claim 3 wherein the the planar rotor has a flow deflector and turbine vanes.

5) The burner of claim 4 wherein the flow of the air-fuel mixture past the turbine vanes causes the rotor to spin and further mix the air and fuel in the air-fuel mixture. 6) The burner of claim 4 wherein a spin inducing means is coupled to the rotor to cause the rotor to spin and further mix the air and fuel in the air-fuel mixture.

7) The burner of claim 6 wherein the spin inducing means is an electric motor.

8) The burner of claim 6 wherein the spin inducing means is a fluidic motor.

9) The burner of claim 2 wherein there are at least two jets of the gaseous fuel which are directed to the planar surface of the gas turbulator means.