US20090098496A1 - Heat exchanger with nox-reducing triangle - Google Patents

Heat exchanger with nox-reducing triangle Download PDF

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Publication number
US20090098496A1
US20090098496A1 US11/873,036 US87303607A US2009098496A1 US 20090098496 A1 US20090098496 A1 US 20090098496A1 US 87303607 A US87303607 A US 87303607A US 2009098496 A1 US2009098496 A1 US 2009098496A1
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Prior art keywords
insert
heat exchanger
recited
combustion tube
frame
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Abandoned
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US11/873,036
Inventor
Randal J. Poirier
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Lennox Manufacturing Inc
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Lennox Manufacturing Inc
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Priority to US11/873,036 priority Critical patent/US20090098496A1/en
Assigned to LENNOX MANUFACTURING INC. reassignment LENNOX MANUFACTURING INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: POIRIER, RANDAL J.
Publication of US20090098496A1 publication Critical patent/US20090098496A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C3/00—Combustion apparatus characterised by the shape of the combustion chamber
    • F23C3/002—Combustion apparatus characterised by the shape of the combustion chamber the chamber having an elongated tubular form, e.g. for a radiant tube
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/46—Details, e.g. noise reduction means
    • F23D14/70—Baffles or like flow-disturbing devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M9/00—Baffles or deflectors for air or combustion products; Flame shields
    • F23M9/08—Helical or twisted baffles or deflectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M9/00—Baffles or deflectors for air or combustion products; Flame shields
    • F23M9/10—Baffles or deflectors formed as tubes, e.g. in water-tube boilers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4935—Heat exchanger or boiler making
    • Y10T29/49361—Tube inside tube

Definitions

  • the invention is directed, in general, to heat exchangers and, more specifically, to an insert for a furnace heat exchanger having improved suppression characteristics of the production of nitrogen oxides.
  • Combustion heaters of conventional heating systems often employ tubular combustion chambers wherein air is mixed with a gaseous fuel, the mixture is burned, and the combustion products are directed to a flue and ultimately to an exhaust.
  • Air to be conditioned is usually returned from a living/working space and passed over the tubular combustion chambers, taking on heat from the combustion chambers and then the air is routed back to the living/working space.
  • combustion systems normally generate gaseous combustion products which include oxides of nitrogen (NO x ) which are vented to the atmosphere as flue gas. It is desirable to limit these NO x emissions since NO x is considered a pollutant and combustion systems sold in certain jurisdictions must meet strict NO x emission standards.
  • One technique for limiting NO x emissions from a combustion system is to control peak combustion flame temperatures that contact the tubular combustion chambers as well as limiting the residence times at these peak combustion flame temperatures to minimize the formation of NO x . It has been known that peak combustion flame temperatures can be controlled by placing a flame holder inserted into the combustion tube to substantially contain the flame, thereby substantially preventing the flame from direct contact with the combustion tube. Tests have shown that such inserts having a substantially square cross-section will just meet the South Coast NO x emissions requirements. Some prior art have gone so far as to state that theoretical work confirmed by experiments indicate that the precise shape of the flame holder is not critical; thereby implying that results will be substantially equivalent among all shapes.
  • one aspect of the invention provides a heat exchanger having a frame and a combustion tube mounted to the frame wherein the combustion tube is configured to contain a flame produced from a fuel/air mixture introduced therein and to exhaust combustion products of the fuel/air mixture.
  • the improvement comprises an insert coupled to the frame and having a longitudinal axis extending along and within the combustion tube wherein the insert has a triangular cross-section normal the longitudinal axis and configured to intersect a periphery of the flame.
  • a method of manufacturing a heat exchanger is also provided.
  • FIG. 1A illustrates a partially-exploded isometric view of a burner/heat exchanger constructed according to the principles of the present invention
  • FIG. 1B illustrates an end view of the vestibule panel with the burner assembly of FIG. 1A removed and showing one insert;
  • FIG. 2 illustrates a sectional view of the heat exchanger along plane A-A of FIG. 1B with the burner shown and an inset of the insert in relation to the combustion tube;
  • FIG. 3 illustrates an isometric view of the insert of FIG. 1 ;
  • FIG. 4 illustrates a graph of NO x test results for a variety of inserts for comparison.
  • the burner/heat exchanger 100 comprises a frame 110 , at least one combustion tube 120 , at least one insert 130 and a burner assembly 140 .
  • the burner/heat exchanger 100 comprises a plurality of combustion tubes 120 a - 120 g , each combustion tube 120 a - 120 g having an insert 130 therein.
  • the frame 110 comprises a vestibule panel 111 coupled to the combustion tubes 120 a - 120 g and a corbel plate 112 coupled to burners 113 a - 113 g .
  • the plurality of combustion tubes 120 a - 120 g , inserts 130 (collectively), and vestibule panel 111 may be collectively referred to as a heat exchanger 150
  • FIG. 1B illustrated is an end view of the vestibule panel 111 with the burner assembly 140 of FIG. 1A removed and showing one insert 130 .
  • the insert 130 comprises three sides 131 - 133 and a tab 134 .
  • the insert 130 is coupled to and supported by the tab 134 that is coupled to the frame 110 in any conventional manner.
  • the tab 134 is captured between the vestibule panel 111 and the corbel plate 112 .
  • FIG. 2 illustrated is a sectional view of the heat exchanger 150 along plane A-A of FIG. 1B with the burner 113 a shown and an inset of the insert 130 a in relation to the combustion tube 120 a and primary combustion zone 231 .
  • the insert is specifically insert 130 a .
  • the tab 134 is captured between the vestibule panel 111 and the corbel plate 112 thereby supporting the insert sides 131 - 133 (side 132 not visible) above the inside bottom, and below the inside top, of the combustion tube 120 a . Therefore, only the tab 134 contacts any part of the frame 110 or the combustion tube 120 a .
  • a centerline 235 of the insert 130 a is in line with a center line 114 of the burner 113 a .
  • the insert sides 131 - 133 are prevented from contacting any portion of the combustion tube 120 a .
  • a secondary combustion zone 232 occurs within the insert 130 a wherein a periphery 233 of the secondary combustion zone 232 is intersected by the insert 130 a.
  • the insert 130 a comprises first, second and third sides 131 - 133 forming a substantially equilateral triangular cross-section and a tab 134 . Note the substantially equilateral triangular cross-section normal to the centerline 235 .
  • the first, second and third sides 131 - 133 are porous, e.g., a wire mesh.
  • the first, second and third sides 131 - 133 comprise a stainless steel, e.g., stainless steel alloy 310.
  • stainless steel is defined as an iron-carbon alloy with a minimum of 10.5% chromium content according to the American Iron and Steel Institute. More specifically, stainless steel alloy 310 alloy comprises between 24.0% and 26.0% chromium, between 19.0% and 22.0% nickel, and maximums of: 0.25% carbon, 2.0% manganese, 1.5% silicon, 0.045% phosphorus, and 0.030% sulfur. Stainless steel alloy 310 is especially suited for use in high temperature applications as it resists oxidation well at temperatures up to 1150° C.
  • High fire and low fire refer to a two-stage burner/heat exchanger controlled by the gas valve. High fire condition is defined as 150 KBtu/hr; while low fire is defined as 105 KBtu/hr.
  • References to percentages refer to the input of gas to the burner with 100% being the amount of gas for which the heat exchanger is designed and name plated as.
  • References to 112% gas input refer to an American National Standards Institute (ANSI) American National Standard (ANS) 21.47, Section 2.8 requirement for over-fired heat exchangers.
  • All cylindrical tubes were alloy 304 stainless steel (SS) with identical wall thickness of 0.045 in.
  • the insert of the present invention comprised alloy 310 stainless steel mesh.
  • the first column shows that the NO x emissions from a burner/heat exchanger without an insert were measured at 64 ng/J of NO x at a high fire condition.
  • Column two shows that with a cylindrical insert having a 1.25′′ diameter and a 6′′ length, the burner/heat exchanger produced 47 ng/J of NO x at low fire conditions.
  • Column three shows that for the same physical configuration as in column two, the burner/heat exchanger produced 45 ng/J of NO x at 5% below a high fire condition. Therefore, a prior art insert of cylindrical design will significantly reduce NO x emissions but not enough to meet a South Coast Air Quality Management District (SCQAMD) when applying the ANSI standard.
  • SCQAMD South Coast Air Quality Management District
  • a triangular cross section heat exchanger insert has been described and shown to be significantly better at reducing NO x emissions than any prior art despite statements in the prior art that cross sectional shape does not affect performance.
  • the true benefit of using the triangular cross section heat exchanger insert is that furnaces now do not have to be de-rated in allowable gas flow in order to meet the SCAQMD Standard.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)

Abstract

A heat exchanger having a frame and a combustion tube mounted to the frame wherein the combustion tube is configured to contain a flame produced from a fuel/air mixture introduced therein, and the combustion tube is configured to exhaust combustion products of the fuel/air mixture, the improvement comprising an insert coupled to the frame and having a longitudinal axis extending along and within the combustion tube wherein the insert has a triangular cross-section normal the longitudinal axis and configured to intersect a periphery of the flame. A method of manufacturing a heat exchanger is also provided.

Description

    TECHNICAL FIELD OF THE INVENTION
  • The invention is directed, in general, to heat exchangers and, more specifically, to an insert for a furnace heat exchanger having improved suppression characteristics of the production of nitrogen oxides.
    • BACKGROUND OF THE INVENTION
  • Combustion heaters of conventional heating systems often employ tubular combustion chambers wherein air is mixed with a gaseous fuel, the mixture is burned, and the combustion products are directed to a flue and ultimately to an exhaust. Air to be conditioned is usually returned from a living/working space and passed over the tubular combustion chambers, taking on heat from the combustion chambers and then the air is routed back to the living/working space. As a result of the combustion process, combustion systems normally generate gaseous combustion products which include oxides of nitrogen (NOx) which are vented to the atmosphere as flue gas. It is desirable to limit these NOx emissions since NOx is considered a pollutant and combustion systems sold in certain jurisdictions must meet strict NOx emission standards.
  • One technique for limiting NOx emissions from a combustion system is to control peak combustion flame temperatures that contact the tubular combustion chambers as well as limiting the residence times at these peak combustion flame temperatures to minimize the formation of NOx. It has been known that peak combustion flame temperatures can be controlled by placing a flame holder inserted into the combustion tube to substantially contain the flame, thereby substantially preventing the flame from direct contact with the combustion tube. Tests have shown that such inserts having a substantially square cross-section will just meet the South Coast NOx emissions requirements. Some prior art have gone so far as to state that theoretical work confirmed by experiments indicate that the precise shape of the flame holder is not critical; thereby implying that results will be substantially equivalent among all shapes.
  • Accordingly, what is needed in the art is a device that provides a significant further reduction in furnace NOx emissions over the conventional art.
    • SUMMARY OF THE INVENTION
  • To address the above-discussed deficiencies of the prior art, one aspect of the invention provides a heat exchanger having a frame and a combustion tube mounted to the frame wherein the combustion tube is configured to contain a flame produced from a fuel/air mixture introduced therein and to exhaust combustion products of the fuel/air mixture. The improvement comprises an insert coupled to the frame and having a longitudinal axis extending along and within the combustion tube wherein the insert has a triangular cross-section normal the longitudinal axis and configured to intersect a periphery of the flame. A method of manufacturing a heat exchanger is also provided.
  • The foregoing has outlined certain aspects and embodiments of the invention so that those skilled in the pertinent art may better understand the detailed description of the invention that follows. Additional aspects and embodiments will be described hereinafter that form the subject of the claims of the invention. Those skilled in the pertinent art should appreciate that they can readily use the disclosed aspects and embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the invention. Those skilled in the pertinent art should also realize that such equivalent constructions do not depart from the scope of the invention.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • For a more complete understanding of the invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
  • FIG. 1A illustrates a partially-exploded isometric view of a burner/heat exchanger constructed according to the principles of the present invention;
  • FIG. 1B illustrates an end view of the vestibule panel with the burner assembly of FIG. 1A removed and showing one insert;
  • FIG. 2 illustrates a sectional view of the heat exchanger along plane A-A of FIG. 1B with the burner shown and an inset of the insert in relation to the combustion tube;
  • FIG. 3 illustrates an isometric view of the insert of FIG. 1; and
  • FIG. 4 illustrates a graph of NOx test results for a variety of inserts for comparison.
    •  DETAILED DESCRIPTION
  • Referring initially to FIG. 1A, illustrated is a partially exploded isometric view of a burner/heat exchanger 100 constructed according to the principles of the present invention. The burner/heat exchanger 100 comprises a frame 110, at least one combustion tube 120, at least one insert 130 and a burner assembly 140. In a preferred embodiment, the burner/heat exchanger 100 comprises a plurality of combustion tubes 120 a-120 g, each combustion tube 120 a-120 g having an insert 130 therein. In one embodiment, the frame 110 comprises a vestibule panel 111 coupled to the combustion tubes 120 a-120 g and a corbel plate 112 coupled to burners 113 a-113 g. The plurality of combustion tubes 120 a-120 g, inserts 130 (collectively), and vestibule panel 111 may be collectively referred to as a heat exchanger 150
  • Referring now to FIG. 1B, illustrated is an end view of the vestibule panel 111 with the burner assembly 140 of FIG. 1A removed and showing one insert 130. Of course, it is understood that for maximum efficiency each combustion tube 120 a-120 g would have a similar insert 130. In this view it can be seen that the insert 130 comprises three sides 131-133 and a tab 134. The insert 130 is coupled to and supported by the tab 134 that is coupled to the frame 110 in any conventional manner. In one embodiment, the tab 134 is captured between the vestibule panel 111 and the corbel plate 112.
  • Referring now to FIG. 2, illustrated is a sectional view of the heat exchanger 150 along plane A-A of FIG. 1B with the burner 113 a shown and an inset of the insert 130 a in relation to the combustion tube 120 a and primary combustion zone 231. In this particular view the insert is specifically insert 130 a. In this sectional view, it can be seen that the tab 134 is captured between the vestibule panel 111 and the corbel plate 112 thereby supporting the insert sides 131-133 (side 132 not visible) above the inside bottom, and below the inside top, of the combustion tube 120 a. Therefore, only the tab 134 contacts any part of the frame 110 or the combustion tube 120 a. Note that a centerline 235 of the insert 130 a is in line with a center line 114 of the burner 113 a. In the insert, it can more readily be seen that the insert sides 131-133 are prevented from contacting any portion of the combustion tube 120 a. A secondary combustion zone 232 occurs within the insert 130 a wherein a periphery 233 of the secondary combustion zone 232 is intersected by the insert 130 a.
  • Referring now to FIG. 3, illustrated is an isometric view of the insert 130 a of FIG. 1. The insert 130 a comprises first, second and third sides 131-133 forming a substantially equilateral triangular cross-section and a tab 134. Note the substantially equilateral triangular cross-section normal to the centerline 235. In one embodiment, the first, second and third sides 131-133 are porous, e.g., a wire mesh. In a preferred embodiment, the first, second and third sides 131-133 comprise a stainless steel, e.g., stainless steel alloy 310. Generally speaking, stainless steel is defined as an iron-carbon alloy with a minimum of 10.5% chromium content according to the American Iron and Steel Institute. More specifically, stainless steel alloy 310 alloy comprises between 24.0% and 26.0% chromium, between 19.0% and 22.0% nickel, and maximums of: 0.25% carbon, 2.0% manganese, 1.5% silicon, 0.045% phosphorus, and 0.030% sulfur. Stainless steel alloy 310 is especially suited for use in high temperature applications as it resists oxidation well at temperatures up to 1150° C.
  • Referring now to FIG. 4, illustrated is a graph of NOx test results for a variety of inserts for comparison. Conditions for testing were as follows. High fire and low fire refer to a two-stage burner/heat exchanger controlled by the gas valve. High fire condition is defined as 150 KBtu/hr; while low fire is defined as 105 KBtu/hr. References to percentages refer to the input of gas to the burner with 100% being the amount of gas for which the heat exchanger is designed and name plated as. References to 112% gas input refer to an American National Standards Institute (ANSI) American National Standard (ANS) 21.47, Section 2.8 requirement for over-fired heat exchangers. That is a maximum of 40 ng/J of NOx emission with a carbon monoxide (CO) level not exceeding 400 ppm corrected air free. All cylindrical tubes were alloy 304 stainless steel (SS) with identical wall thickness of 0.045 in. The insert of the present invention comprised alloy 310 stainless steel mesh.
  • As a standard against which the inserts can be judged, the first column shows that the NOx emissions from a burner/heat exchanger without an insert were measured at 64 ng/J of NOx at a high fire condition. Column two shows that with a cylindrical insert having a 1.25″ diameter and a 6″ length, the burner/heat exchanger produced 47 ng/J of NOx at low fire conditions. Column three shows that for the same physical configuration as in column two, the burner/heat exchanger produced 45 ng/J of NOx at 5% below a high fire condition. Therefore, a prior art insert of cylindrical design will significantly reduce NOx emissions but not enough to meet a South Coast Air Quality Management District (SCQAMD) when applying the ANSI standard. By comparison, columns four and five show that with a cylindrical insert having a 1.25″ diameter and an 11″ length, the burner/heat exchanger produced 41 ng/J of NOx at both low fire and high fire conditions—not quite meeting the SCAQMD standard. Therefore, it is clear that the length of the insert has a measurable effect on the effectiveness of the insert.
  • Columns six and seven show that with a cylindrical insert having a 1.00″ diameter and a 6″ length, the burner/heat exchanger produced 41 ng/J of NOx at low fire and 40 ng/J of NOx at high fire. However, the 304 SS failed during this test, likely due to the smaller diameter causing impingement of a greater surface of the flame on the insert. Columns eight and nine show that for a cylindrical insert having a 0.75″ diameter and a 6″ length, the burner/heat exchanger produced 40 ng/J of NOx at low fire and 42 ng/J of NOx at high fire. Therefore, while a cylindrical insert does work to reduce emissions, the reduction is usually not quite enough to meet the SCAQMD Standard.
  • Columns 10 and 11 show that for a rectangular/square insert having a 1.125″ side and a 10″ length, the burner/heat exchanger produced 39 ng/J of NOx at low fire and 36 ng/J of NOx at high fire, thereby meeting the SCAQMD Standard. This configuration approximates the prior art wherein it was stated that shape of the insert was not a governing factor in the performance of the insert.
  • Columns 12 and 13 show that for a triangular insert having a 1.5″ side and a 10″ length, the burner/heat exchanger produced 35 ng/J of NOx at low fire—a more than 10 percent improvement over the prior art at low fire. Additionally, with the triangular insert the burner/heat exchanger produced 30 ng/J of NOx at high fire—an almost 17 percent improvement over the prior art at high fire. Thus, it has been shown that the cross sectional shape of the insert does have an effect on the performance in that rectangular/square inserts are better than round cross sections. Furthermore, triangular cross sectional inserts are significantly better performers compared to either rectangular/square or round cross sections.
  • Thus, a triangular cross section heat exchanger insert has been described and shown to be significantly better at reducing NOx emissions than any prior art despite statements in the prior art that cross sectional shape does not affect performance. The true benefit of using the triangular cross section heat exchanger insert is that furnaces now do not have to be de-rated in allowable gas flow in order to meet the SCAQMD Standard.
  • Those skilled in the art to which the invention relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments without departing from the scope of the invention.

Claims (16)

1. In a heat exchanger having a frame and a combustion tube mounted to said frame, said combustion tube configured to contain a flame produced from a fuel/air mixture introduced therein and to exhaust combustion products of said fuel/air mixture, the improvement comprising:
an insert coupled to said frame and having a longitudinal axis extending along and within said combustion tube, said insert having a triangular cross-section normal said longitudinal axis, said insert configured to intersect a periphery of said flame.
2. The heat exchanger as recited in claim 1 wherein said triangular cross section is substantially an equilateral triangular cross section.
3. The heat exchanger as recited in claim 1 wherein said insert is porous.
4. The heat exchanger as recited in claim 1 wherein said insert comprises a wire mesh.
5. The heat exchanger as recited in claim 1 wherein said insert comprises an alloy of stainless steel.
6. The heat exchanger as recited in claim 1 wherein said insert comprises stainless steel 310.
7. The heat exchanger as recited in claim 1 wherein said insert comprises an alloy of iron, chromium and nickel.
8. The heat exchanger as recited in claim 1 further comprising a mounting tab coupled to said insert, said mounting tab configured to support said insert within, but not in contact with, said combustion tube.
9. A method of manufacturing a heat exchanger having a frame and a combustion tube mounted to said frame, said combustion tube configured to contain a flame produced from a fuel/air mixture introduced therein and to exhaust combustion products of said fuel/air mixture, the improvement comprising:
coupling an insert to said frame, said insert having a longitudinal axis extending along and within said combustion tube, said insert having a triangular cross-section normal said longitudinal axis and configured to intersect a periphery of said flame.
10. The method as recited in claim 9 wherein coupling includes coupling an insert wherein said triangular cross section is substantially an equilateral triangular cross section.
11. The method as recited in claim 9 wherein coupling includes coupling an insert wherein said insert is porous.
12. The method as recited in claim 9 wherein coupling includes coupling an insert wherein said insert comprises a wire mesh.
13. The method as recited in claim 9 wherein coupling includes coupling an insert wherein said insert comprises an alloy of stainless steel.
14. The method as recited in claim 9 wherein coupling includes coupling an insert wherein said insert comprises stainless steel 310.
15. The method as recited in claim 9 wherein coupling includes coupling an insert wherein said insert comprises an alloy of iron, chromium and nickel.
16. The method as recited in claim 9 further comprising coupling a mounting tab to said insert, and configuring said mounting tab to support said insert within, but not in contact with, said combustion tube.
US11/873,036 2007-10-16 2007-10-16 Heat exchanger with nox-reducing triangle Abandoned US20090098496A1 (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8479720B1 (en) 2008-10-16 2013-07-09 Oscar Enrique Figueroa Heating device and method
US20190101282A1 (en) * 2017-10-03 2019-04-04 Lennox Industries Inc. BURNER BOX LINER FOR LOW NOx EMISSION FURNACE
US10544961B2 (en) * 2016-02-18 2020-01-28 Lennox Industries Inc. Premix burner internal flue shield
US10697668B2 (en) 2016-02-18 2020-06-30 Lennox Industries Inc. Flue baffle
US10711998B2 (en) 2017-10-03 2020-07-14 Lennox Industries Inc. Fresh air intake for low NOx emission furnace
US11162677B2 (en) 2019-01-18 2021-11-02 Lennox Industries Inc. Air intake coupling with noise suppression for low NOx emission furnace
US11187433B2 (en) 2017-10-03 2021-11-30 Lennox Industries Inc. Pre-mix burner assembly for low NOx emission furnace

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US5370529A (en) * 1993-08-24 1994-12-06 Rheem Manufacturing Company Low NOx combustion system for fuel-fired heating appliances
US5458484A (en) * 1994-05-16 1995-10-17 Carrier Corporation Pre-mix flame type burner
US5546925A (en) * 1995-08-09 1996-08-20 Rheem Manufacturing Company Inshot fuel burner Nox reduction device with integral positioning support structure
US5580238A (en) * 1995-12-18 1996-12-03 Carrier Corporation Baffle for NOx and noise reduction
US5596979A (en) * 1995-12-18 1997-01-28 Carrier Corporation Sound inhibitor baffles
US5649529A (en) * 1995-10-12 1997-07-22 Rheem Manufacturing Company Low NOx combustion system for fuel-fired heating appliances
US5730116A (en) * 1996-07-22 1998-03-24 Rheem Manufacturing Company NOX reducing combustor tube insert apparatus

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US4776320A (en) * 1985-07-31 1988-10-11 Carrier Corporation Device for inhibiting NOx formation by a combustion system
US5333597A (en) * 1993-04-30 1994-08-02 Consolidated Industries Corp. Abatement member and method for inhibiting formation of oxides of nitrogen
US5370529A (en) * 1993-08-24 1994-12-06 Rheem Manufacturing Company Low NOx combustion system for fuel-fired heating appliances
US5458484A (en) * 1994-05-16 1995-10-17 Carrier Corporation Pre-mix flame type burner
USRE36743E (en) * 1994-05-16 2000-06-20 Carrier Corporation Pre-mix flame type burner
US5546925A (en) * 1995-08-09 1996-08-20 Rheem Manufacturing Company Inshot fuel burner Nox reduction device with integral positioning support structure
US5649529A (en) * 1995-10-12 1997-07-22 Rheem Manufacturing Company Low NOx combustion system for fuel-fired heating appliances
US5580238A (en) * 1995-12-18 1996-12-03 Carrier Corporation Baffle for NOx and noise reduction
US5596979A (en) * 1995-12-18 1997-01-28 Carrier Corporation Sound inhibitor baffles
US5730116A (en) * 1996-07-22 1998-03-24 Rheem Manufacturing Company NOX reducing combustor tube insert apparatus

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8479720B1 (en) 2008-10-16 2013-07-09 Oscar Enrique Figueroa Heating device and method
US10544961B2 (en) * 2016-02-18 2020-01-28 Lennox Industries Inc. Premix burner internal flue shield
US10697668B2 (en) 2016-02-18 2020-06-30 Lennox Industries Inc. Flue baffle
US20190101282A1 (en) * 2017-10-03 2019-04-04 Lennox Industries Inc. BURNER BOX LINER FOR LOW NOx EMISSION FURNACE
US10711997B2 (en) * 2017-10-03 2020-07-14 Lennox Industries Inc. Burner box liner for low NOx emission furnace
US10711998B2 (en) 2017-10-03 2020-07-14 Lennox Industries Inc. Fresh air intake for low NOx emission furnace
US11187433B2 (en) 2017-10-03 2021-11-30 Lennox Industries Inc. Pre-mix burner assembly for low NOx emission furnace
US11543123B2 (en) 2017-10-03 2023-01-03 Lennox Industries Inc. Burner box liner for low NOx emission furnace
US11598557B2 (en) 2017-10-03 2023-03-07 Lennox Industries Inc. Pre-mix burner assembly for low NOx emission furnace
US11808449B2 (en) 2017-10-03 2023-11-07 Lennox Industries Inc. Fresh air intake for low NOx emission furnace
US11162677B2 (en) 2019-01-18 2021-11-02 Lennox Industries Inc. Air intake coupling with noise suppression for low NOx emission furnace

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