EP1853851A1

EP1853851A1 - Low nox pilot burner and associated method of use

Info

Publication number: EP1853851A1
Application number: EP06720654A
Authority: EP
Inventors: Frederick Dean Lyles
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 2005-02-11
Filing date: 2006-02-10
Publication date: 2007-11-14
Also published as: WO2006086714A1; WO2006086714B1; MX2007009720A; US20060199124A1

Abstract

The pilot burner assembly and associated method of use is disclosed. This includes a pilot burner having a top portion, a middle portion and a bottom portion, wherein the top portion of the pilot burner includes a hood that is positioned adjacent to an igniter and a thermocouple. The middle portion of the pilot burner includes at least one opening providing an air inlet. During situations where LDO (lint-dust-oil) build-up has occurred, the hood will continue to provide flame to a main burner, but the flame to heat the thermocouple will shrink or lift to the point where it no longer can heat the thermocouple sufficiently to generate enough power to allow for a safety magnet valve to remain energized. This will result in the shutting-off of the associated gas-fired device.

Description

LOW NOx PILOT BURNER AND ASSOCIATED METHOD OF USE

RELATED APPLICATIONS

This application is related to and claims priority from U.S. provisional patent application serial number 60/593,776 filed February 11₅ 2005, having inventor Frederick D. Lyles, entitled "Low NOx Pilot Burner And Associated Method Of Use."

BACKGROUND OF THE INVENTION

All gas burners are susceptible to lint, dust or oil (LDO) accumulation in harsh environments. These gas burners must shut down before exceeding carbon monoxide (CO) limits. When there is an accumulation of lint, dust or oil, this can cause the gas burner flame to flatten out and increase the internal temperature of the gas appliance's combustion chamber. Therefore, it is desired to have a pilot burner that will shut down when there is an excessive amount of lint, dust or oil. An illustrative, but nonlimiting example, of a gas appliance that utilizes a gas burner is a water heater. Moreover, it is desirable to have a low NOx pilot burner. This is due to the fact that NOx is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts.

There are now standards that dictate that a water heater must not produce flue gases that contain carbon monoxide in excess of 0.04 (%) percent on an air free basis when exposed to lint, dust or oil. These test standards are listed under ANSI Z21.10.1b-2004, CSA 4.1b- 2004, Section 2.36 as "Resistance to Lint, Dust and Oil Accumulation." This is also mandated by regulation such as the South Coast Air Quality Management District's Rule 1121 for "Control of Nitrogen Oxides from Residential Type, Natural Gas-Fired Water Heaters." This Rule dictates the NOx emission level per joule of heat output.

The present invention is directed to overcoming one or more of the problems set forth above.

SUMMARY OF THE INVENTION

An aspect of the present invention is a pilot burner assembly. The pilot burner assembly includes a pilot burner having a top portion, middle portion and a bottom portion, wherein the top portion of the pilot burner includes a hood that is positioned adjacent to an igniter and a thermocouple. A middle portion of the pilot burner includes at least one opening providing an air inlet.

Another aspect of the present invention may optionally include a bracket assembly. The bracket assembly may be operatively attached to a pilot burner, a thermocouple assembly and an igniter assembly. Preferably, but not necessarily, a pilot burner is mounted at an angle with the thermocouple located lower than the pilot burner hood, e.g., 60° +/- 15° in relationship to the bracket assembly. The bracket assembly may include a vertical portion with attachment holes as well as a u-shaped bracket with an upper opening and a lower opening for receiving a thermocouple. Optionally, the bracket assembly may include a first top plate and a second top plate connected together.

Still another aspect of the present invention may optionally include a hood. The hood may have at least one opening and preferably includes more than one opening to form a multiple-way hood, e.g., two-way hood. The at least one opening can include a wide variety of geometric shapes and sizes but is preferably triangular with an opening that can provide flame direction and pattern as well as a spark path between an igniter and a pilot burner.

Yet another aspect of the present invention may optionally include an insert. The insert may include an upper portion, a middle portion and a lower portion. Optionally, the middle portion can include a flange can be positioned on top of a bracket assembly and the lower portion can be threaded. The presence of lint, dust and/or oil will restrict at least one opening, e.g., four (4), created by a hole(s) or slot(s) forming at least one primary air intake orifice. A primary air intake orifice is located in the middle portion of the insert that extends from an inner chamber of the insert to an outer surface of the middle portion of the insert.

In still another aspect of the present invention may optionally include an orifice spud. The orifice spud controls the primary flow of gas in the pilot burner and restricts the flow of gas. The orifice spud may include a first sidewall, a second sidewall and a nozzle. The nozzle may include an opening. The opening may include a first slot and a second slot that are positioned transverse, e.g., perpendicular, to each other and in fluid communication.

Another aspect of the present invention may optionally include a ball sleeve. The ball sleeve may provide a compression seal between an orifice spud and a compression nut. Optionally, the ball sleeve may include a triangular portion.

Still another aspect of the present invention may optionally include a compression nut. The compression nut may provide connection to a gas valve and operate to compress a ball sleeve. The compression nut may be threadedly attached to a threaded end portion for an insert. It is another aspect of the present invention includes an igniter. The igniter may include a protruding electrode that can be bent to extend adjacent to an opening in a hood. There may be an insulator that can secure the electrode. An illustrative, but nonlimiting insulator can include ceramic material. The electrode is preferably at least partially covered in an insulating material. The insulator may be secured in the bracket assembly with an upper ring and a combination electrode holder and retainer.

Yet another aspect of the present invention is a method of utilizing a pilot burner assembly. The method includes positioning a pilot burner, having a top portion, a middle portion and a bottom portion, near a thermocouple and an igniter so that when at least one opening providing an air inlet in the middle portion of the pilot burner is at least partially blocked with lint, oil or dust, then the flame to heat the thermocouple will shrink or lift to the point where it no longer can heat the thermocouple sufficiently to generate enough power to allow for a safety magnet valve to remain energized and will shut-off the associated gas-fired device.

These and other features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment which, taken in conjunction with the accompanying drawings, illustrates by way of example the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference may be made to the accompanying drawings in which:

FIG. 1 is a perspective view of the pilot burner of the present invention mounted to a main burner;

FIG. 2 is an isolated perspective view of an igniter assembly, a thermocouple assembly and a pilot burner in accordance with the present invention;

FIG. 3 is an exploded, perspective view of the pilot burner in accordance with the present invention and as shown in FIG. 2;

FIG. 4 is a top view of an insert associated with the pilot burner shown in FIG. 3 ;

FIG. 5 is a cross-sectional view of the insert associated with the pilot burner valve taken along Line 4-4 of FIG 4;

FIG. 6 is a cross-sectional view of the insert associated with the pilot burner valve taken along Line 5-5 of FIG 5; FIG. 7 is an isolated view of the igniter assembly in accordance with the present invention and as shown in FIG. 2;

FIG. 8 is a side, cross-sectional view of an orifice spud in accordance with the present invention and as shown in FIG. 3;

FIG. 9 is a top view of an orifice spud in accordance with the present invention and as shown in FIG. 8;

FIG. 10 is a magnified top view of the orifice spud in accordance with the present invention and as shown in FIG. 9;

FIG. 11 is a top view of a ball sleeve in accordance with the present invention and as shown in FIG. 3;

FIG. 12 is a cross-sectional view of the ball sleeve associated with the present invention taken along Line 11-11 of FIG Il; and

FIG. 13 is a top view of a compression nut in accordance with the present invention and as shown in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

While the various features of this invention are hereinafter illustrated and described as being particularly adapted to provide a pilot burner construction for burning gaseous fuel, such as natural or synthetic gas, it is to be understood that the various features of this invention can be utilized singly or in various combinations thereof to provide a pilot burner construction for other types of apparatus as desired. A typical pilot burner is disclosed in U.S. Patent No. 5,039,300, which issued to Riehl on August 13, 1991, which is incorporated herein by reference. Another example of a pilot burner is disclosed in U.S. Patent Application No. 20030183177, published on October 2, 2003 to Kobayashi et al, which is incorporated herein by reference as well as U.S. Patent Application No. 20010003274, published on June 14, 2001, which is incorporated herein by reference.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention. The valve of the present invention is especially suited for controlling the flow of a combustible gas to a gas-fired appliance such as a furnace, a water heater or a gas- burning fireplace.

As shown in FIG. 1, a pilot burner is generally indicated by numeral 10. The pilot burner 10 will be mounted adjacent to a thermocouple 20. Preferably, but not necessarily, the pilot burner 10 is mounted at an angle with the thermocouple 20 located lower than the pilot burner hood 12, e.g., 60° +/- 15°. During normal operation, a hood 12 will provide flame to heat the thermocouple 20 and ignite a main burner 2. The thermocouple 20 will allow the safety magnet valve (not shown) to remain energized so that gas can flow into a main burner 2.

During situations where LDO (lint-dust-oil) build-up has occurred, the hood 12 will continue to provide flame to the main burner 2, but the flame to heat the thermocouple 20 will shrink or lift to the point where it no longer can heat the thermocouple 20 sufficiently to generate enough power to allow for the safety magnet valve (not shown) to remain energized. This will result in an associated gas-fired device shutting off. The thermocouple 20 is essentially a sensor that is utilized in a gas-fired device for detecting heat from the pilot burner 10. There is an igniter 22 for providing a spark to ignite the pilot burner 10 that is located adjacent to the hood 12 of the pilot burner 10.

Referring now to FIG. 2, an igniter 22 and an associated insulator 24 are attached to a bracket assembly 100 that includes a vertical portion 102 with attachment holes 105. The bracket assembly 100 may include a u-shaped bracket 108 with an upper opening 103 and a lower opening 104 for receiving the thermocouple 20, as shown in FIG. 1. This can include a first top plate and a second top plate that are connected together. Any mechanical or chemical connection mechanism will suffice such as a rivet 199. Alternatively, the assembly 100 may be unitary. The bracket assembly 100 is preferably, but not necessarily, designed to withstand at least fifty (50) pounds of push-out force and one hundred and twenty (120) footpounds of rotation torque.

There is also the pilot burner 10 that includes the hood 12 that is mounted on top of the bracket assembly 100 with extending flange members 101, e.g., four (4). There are holes or slots 112 creating primary air intake orifices located underneath the hood 12 and just above the bracket assembly 100. However, these holes or slots 112 are not limited to being positioned just above the bracket 100 and can be located along the length of the pilot burner 10 both above and below the bracket 100.

Referring now to FIG. 3, which is an exploded version of the pilot burner 10 shown in FIG. 2, which includes the hood 12 having a first triangular opening 8 and a second triangular opening 9 to create the two-way opening. Although two, triangular-shaped openings are preferred to create a two-way opening, the hood 12 can include a wide variety of geometric shapes, sizes and number of openings. Preferably, but not necessarily, there is a plurality of extending flange members 101 extending outward from the bottom of the hood 12, e.g., four (4). The hood 12 provides flame direction and pattern as well as a spark path between the igniter 22 and the pilot burner 10. The hood 12 is preferably located adjacent to the igniter 22, as shown in FIG. 1.

Referring now to FIGS. 3, 4, 5 and 6, there is an insert 202 that includes holes or slots 113 located underneath the hood 12 and just above the bracket assembly 100, as shown in FIG. 2. This insert 202 may include an upper portion 201, a middle portion 207 and a lower portion 206. Optionally, the middle portion 207 may include a flange portion 204 and the lower portion 207 may be threaded. The flange portion 204 is optionally positioned on top of the bracket assembly 100. The presence of lint, dust and/or oil will restrict the at least one opening created by at least one hole or slot 113 forming the at least one primary air intake orifice located in the middle portion 207. This will change the flame characteristics, including the lifting of the flame, to reduce the temperature of the thermocouple 20. When the temperature sensed by the thermocouple 20 is reduced, a safety magnet valve (not shown) will close to stop gas flow to the main burner 2. This insert 202 restricts and controls the gas flow in the pilot burner 10 that provides a small flame to light the main burner 2.

Referring now to FIG. 4, there is a cross-sectional top view of the insert 202. The upper portion 201 and an optional flange portion 204 are shown. Referring now to FIG. 5, the cross section of the insert 202 includes the upper portion 201, the optional flange portion 204 and the end portion 206. There is an inner chamber 260 that is in fluid communication with holes or slots 113, i.e., primary air intake orifices, which extend to the outer surface 262 of the insert 202. The presence of lint, dust and/or oil will restrict the openings created by the holes or slots 113 so that air is restricted from flowing from the holes or slots 113 to the inner chamber 260. This will cause the flame that heats the thermocouple 20, as shown in FIG. I₅ to shrink to the point where it no longer heats the thermocouple 20 effectively and the safety magnet valve (not shown) will close to stop gas flow to the main burner 2. The cross-section defined by Line 5-5 shows the holes or slots 113, i.e., primary air intake orifices, which extend to the outer surface 262 of the insert 202 to the inner chamber 260. The size of the at least one hole or slot 113 functioning as primary air intake orifice(s) can vary depending on the size and dimensions of the pilot burner 10 and the associated gas-fired device.

Positioned within the burner 10 is an orifice spud 220, as shown in FIG. 3. The orifice spud 220 controls the primary flow of gas in the pilot burner 10 and restricts the flow of gas. Referring now to FIG. 8, the orifice spud includes a first sidewall 242, a second sidewall 244 and a nozzle 246. Referring now to FIG. 9, the nozzle 246 includes an opening 248. An illustrative, but nonlimiting, example of an opening 248 includes a first slot 250 and a second slot 252 that are positioned transverse, e.g., perpendicular, to each other and there is fluid communication between the first slot 250 and a second slot 252, as shown in FIG. 10.

There is a ball sleeve 222 to provide a compression seal between the orifice spud 220 and a compression nut 224, as shown in FIGS. 3, 11 and 12. As shown in FIG. 12, the ball sleeve may optionally include a triangular portion 261.

As shown in FIGS. 3 and 13, there is a compression nut 224 to retain the orifice spud 220 and ball sleeve 222. Moreover, the compression nut 224 provides connection to a gas valve and can compress the ball sleeve 222. The compression nut 224 is operatively attached to the end portion 206 for the insert 202, as shown in FIG. 2. Preferably, but not necessarily, this connection is through interconnecting threads on both the compression nut 224 and the end portion 206 of the insert 202.

Referring now to FIG. 7, the igniter assembly is generally indicated by numeral 300. This includes a protruding electrode 22 that can be bent to extend to an opening in the hood 12, as shown in FIG. 1. There is an insulator 24 that can secure the electrode 22. An illustrative, but nonlimiting insulator 24, can include ceramic material. The electrode 22 is then covered in insulating material, e.g., TEFLON®. TEFLON® is a federally registered trademark of E. I. du Pont de Nemours and Company, having a place of business at 1007 Market Street, Wilmington, Delaware 19898. The insulator 24 can be secured in the bracket assembly 100 with an upper ring 310, and a combination electrode holder and retainer 306. There may be a connector to attach a bracket assembly that can support the thermocouple 20, as shown in FIG. 1.

A method of utilizing a pilot burner 10 is also contemplated with an embodiment of the invention. The method includes positioning a pilot burner 10 near a thermocouple 20 and an igniter 22 so that when at least one primary air intake orifice 112 to the pilot burner 10 is at least partially blocked with lint, oil or dust, then the flame to heat the thermocouple 20 will shrink or lift to the point where the pilot burner can no longer can heat the thermocouple 20 sufficiently to generate enough power to allow for a safety magnet valve (not shown) to remain energized and will shut the associated gas-fired device such as the main gas burner 2.

While a particular form of the invention has been illustrated and described, it will also be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited except by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A low NOx emission burner assembly for selectively providing a pilot burner flame comprising: at least one pilot burner hood for directing the pilot burner flame; at least one pilot burner fuel inlet for the introduction into the pilot burner assembly of a flammable fuel; at least one pilot burner air inlet for the introduction into the pilot burner assembly of air to support the combustion of the flammable fuel to produce the pilot burner flame; and a thermocouple assembly for controlling a flow of the flammable fuel to a main burner, the thermocouple assembly being positioned adjacent to one or more of the at least one pilot burner hoods such that during ordinary operation, the thermocouple assembly is activated by the pilot burner flame to allow fuel flow to the main burner, and when the at least one pilot burner air inlet is at least partially blocked such that the pilot burner flame shifts it position while continuing to burn, the change in the pilot burner flame causes the thermocouple assembly to disallow fuel to flow to the main burner.

2. The low NOx emission burner assembly according to claim 1, wherein the at least one pilot burner hood comprises a plurality of pilot burner hoods.

3. The low NOx emission burner assembly according to claim 2, wherein the plurality of pilot burner hoods comprises two pilot burner hoods.

4. The low NOx emission burner assembly according to claim 1, wherein the at least one pilot burner air inlet comprises a plurality of pilot burner air inlets.

5. The low NOx emission burner assembly according to claim 4, wherein the plurality of pilot burner air inlets comprises four pilot burner air inlets.

6. The low NOx emission burner assembly according to claim 1, further comprising an igniter assembly for igniting the flammable fuel, the igniter assembly being positioned adjacent to the at least one pilot burner hood.

7. A method of reducing NOx emissions from a burner assembly comprising: providing a pilot burner hood for directing a pilot burner flame; providing a pilot burner fuel inlet for the introduction into the pilot burner hood of a flammable fuel; providing a pilot burner air inlet for the introduction into the pilot burner hood of air to support the combustion of the flammable fuel to produce the pilot burner flame; providing a main burner assembly operable to act as a heat source via burning of the flammable fuel; and providing a thermocouple assembly for controlling a flow of the flammable fuel to the main burner assembly, including positioning the thermocouple assembly adjacent to the pilot burner hood such that during ordinary operation, the thermocouple assembly is heated by the pilot burner flame to allow fuel flow to the main burner assembly, and such that when the at least one pilot burner air inlet is at least, partially blocked such that the pilot burner flame . shifts it position while continuing to burn, the change in the pilot burner flame causes the thermocouple assembly to disallow fuel to flow to the main burner assembly.

8. The method according to claim 7, wherein the step of providing a pilot burner hood comprises providing a plurality of pilot burner hoods.

9. The method according to claim 8, wherein the step of providing a pilot burner hood comprises providing two pilot burner hoods.

10. The method according to claim 7, wherein the step of providing a pilot burner air inlet comprises providing a plurality of pilot burner air inlets.

11. The method according to claim 10, wherein the step of providing a pilot burner air inlet comprises providing four pilot burner air inlets.

12. The method according to claim 7, further comprising providing an igniter assembly for igniting the flammable fuel, the igniter assembly being positioned adjacent to the pilot burner hood.