US3856457A - Burner of the oxy-fuel type - Google Patents

Abstract

A burner of the type wherein fuel and an oxidizing fluid are combusted to produce a high temperature flame. The burner is characterized in that a combustion chamber is defined by a housing and a plurality of tubes which are arranged therein in a bundle, the tubes conducting fuel to the chamber and interstices defined by the housing and tubes held in spaced relation serving to conduct the oxidizing fluid to the chamber. Also disclosed are relationships between the length and diameter of the combustion chamber and the cross-sectional area of the fuel passages and oxidizing fluid passages so as to keep the operating noise level of the burner at a low level.

Description

United States Patent [191 Miller Dec. 24, 1974 BURNER OF THE OXY-FUEL TYPE [75] Inventor: Keith A. Miller, Allentown, Pa. Primary Exammer*c,arrou i Attorney, Agent, or Frrm-James C. Slmmons; Barry [73] Assrgnee: Air Products and Chemicals, Inc., Moyer'man Allentown, Pa.

[22] Filed: Dec. 29, 1972 57 ABSTRACT PP 319,493 A burner of the type wherein fuel and an oxidizing fluid are combusted to produce ahigh temperature 52 us. Cl 431/353, 239/1323, 239/4243 fl The 9 characterllfiid that m [51 Int. Cl. F23d 15/02 Chamber definfid by a housmg and a Plurahty of 58 Field of Search 431/353, 160; 239/1323, tubes Whlch F arranged them" a 239/4245 tubes conducting fuel to the chamber and 1nterst1ces defined by the housing and tubes held in spaced rela- [561 ca er. 0 rscose rrea1n1 ew e UNITED STATES PATENTS length and diameter of the combustion chamber and Shepherd th ro e tional area of the fuel passages and xi- 3,339,616 9/1967 Ward et a1. 239/1323 dizing fluid passages so as to kefp the Operating noise 3,565,346 2/1971 Carrell 239/4245 level of the burner at a low level 3,638,932 2/1972 Massella et a1. 1 239/1323 3,685,740 8/1972 Shepherd 1 239/1323 3,758,037 9/1973 Marion et a1. 239/1323 12 Clalms 8 Drawmg Figures PATENTEDDEC 2 4 I974 SHEET 1 0F 4 BURNER OF THE OXY-FUEL TYPE BACKGROUND OF THE INVENTION This invention pertains to a burner of the oxy-fuel type used in vessels for melting primary metals or for preheating metals prior to melting in an auxiliary furnace. The burners normally contain a combustion chamber wherein the flame originates and is controlled and directed into specific areas of the vessel or at the materials being heated. Such burners are normally placed in the wall or the roof of the furnace and employ an oxy-fuel mixture such as natural gas and oxygen that is combusted and directed at the proper portion of the furnace.

Oxy-fuel burners of the type containing a combustion chamber and which are suitable for high-temperature metallurgical service are shown in US. Pat. Nos. 3,092,166 and 3,135,626. These Patents disclose a burner wherein the combustion chamber is open on the delivery end (flame end) and is closed at the other end, the closed end containing a plurality of inlets for oxidizing fluid, fuel and in some cases a mixture of oxygen and fuel for pilot flames that serve to anchor the flame front to such a plate. US. Pat. No. 3,425,782 discloses a fuel oil-air burner such as is used in commercial heating devices for heating buildings and the like. The Patent discloses a plurality of tubes inside of the main burner housing for inspirating air into the burner for mixing with the fuel oil. This burner is opened on both ends and relies upon the inspiration of air after combustion has been started.

SUMMARY OF THE INVENTION The present invention relates to a burner that can be used to produce melting temperatures for primary metal refining vessels, glass furnaces, or other refractory lined heating furnaces heated by burners, using fuel and an oxidizing fluid mixture. The burner of the present invention is fluid cooled and is provided with a plurality of tubes in the form of a bundle which tube bundle terminates at the beginning of the combustion chamber. The tube bundle is constructed so that preferably the fuel can be conducted down through the tubes and the oxidizing fluid can be conducted in the interstices, defined by the tube bundle, and a fluid cooled jacket towards the combustion chamber. With such a construction, intimate mixing of the fuel and the oxidizing fluid takes place in the combustion chamber and the flame occurs within the combustion chamber and is projected outwardly of the combustion chamber to provide the heating effect of the burner. The burner of the present invention can be made within certain described parameters for the length and diameter of the combustion chamber so as to minimize the operating noise level of the burner. The number of tubes also effects the noise level and the burner can be made in two sections with a quick change capability so that the combustion chamber end can be easily replaced.

Therefore, it is the primary object of this invention to provide an improved burner.

It is a further object of this invention toprovide a burner for primary melting that contains a combustion chamber for producing a narrow intense flame.

It is still another object of this invention to provide a burner of the oxy-fuel type wherein a plurality of tubes are employed to assure intimate mixing of the oxidizing fluid and the fuel at the entrance to the combustion chamber of the burner by providing an optimum total length of interface between the fuel and oxidizer streams.

It is still a further object of this invention to provide a burner of the oxy-fuel type that is fluid cooled and that can be quickly disassembled to replace the com bustion chamber end thereof.

It is yet another object of this invention to provide a burner of the oxy-fuel type wherein a plurality of tubes are employed to assure complete separation of the oxidizing fluid and the fuel prior to their introduction into the combustion chamber.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric drawing of a burner according to the present invention with portions cut away to re veal the interior details thereof.

FIG. 2 is a longitudinal section of the burner of FIG. 1 taken along the lines 2-2 of FIG. 1.

FIG. 3 is an end view of the burner taken along line 33 of FIG. 1.

FIG. 4 is an isometric drawing of a second embodiment of the burner according to the present invention with portions broken away to show the interior details thereof.

FIG. 5 is a longitudinal section taken along line 5-5 of FIG. 4.

FIG. 6 is a transverse section taken along line 6-6 of FIG. 4.

FIG. 7 is a plot of sound level measured in decibels against the length-to-diameter ratio of the combustion chamber of a burner according to either FIG. 1 or FIG. 4.

FIG. 8 is a plot of sound level measured in decibels a against burner firing rate in millions of BTU per hour illustrating the ratio of the area of the oxidizing fluid passages to the area of the fuel passages.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG 1, there is shown aburner 10 preferably fabricated with a two-piece housing 12 and 14. Thehousing sections 12 and 14 are secured together by a quick-disconnect coupling 16 such as manufactured under the tradename VICTAULIC by the Victaulic Company of America.Such couplings 16 are well known to the industry and form a seal with a pair ofcircumferential grooves 18 and 20 disposed in thehousing sections 12 and 14 respectively. An integral part of thecoupling 16 includes a gasket or sealingmember 22 to prevent fluid leaks from the burner.

Section 14 ofburner 10 has afirst flange 24 fixed to one end as bygirth weld 26.Flange 24 includes a plurality of apertures for receivingbolts 28 for fastening amating flange 32 having therein anelbow conduit 34 to theflange 24. Between theflanges 24 and 32 is disposed a sealingmember 36 such as a sheet of neoprene rubber or other suitable fluid type gasket material. Disposed withinhousing section 14 is a waterjacket positioning ring 38 having therein a sealingmember 40 such as an O-ring. The ring and O-ring 38, 40support sleeve 42 as will hereinafter be more fully described. Communicating with the interior ofsection 14 is afirst conduit adapter 44 and asecond conduit adapter 46 for admitting a source of oxidizing fluid and cooling fluid to the interior of the burner respectively.

Burner section 12 includes anouter shell 48 and theinner shell 42 closed at one end by sealingring 50 as bycircumferential weld 51.Section 12 includes aconduit adapter 52 communicating with the interior of the section betweensleeves 48 and 42 so that when thesections 12 and 14 are assembled thebaffle 54 affixed tosection 14 is disposed between thesections 42 and 48 to define a fluid cooling chamber wherein the water or other fluid coolant is admitted throughfitting 46, proceeds along the outside ofsleeve 42 toward thering 50 and then is removed through fitting 52 by passing between the inner surface ofsleeve 48 andbaffle 54 thereby effectively cooling thesection 12 ofburner 10. Theend 50 ofburner section 12 is generally referred to as the combustion chamber end which defines acombustion chamber 64 betweenend 50 of the burner housing and theend 65 of thetube bundle 58. Disposed within the interior of theburner 10 is a plurality oftubes 58. The tubes are arranged in a bundle and define interstices orspaces 60 therebetween. Thetubes 58 extend through the flange assembly 24-32-36 on the one end and are coextensive toward thecombustion chamber end 50. As shown in FIG. 3 at the end 65 (FIG. 1) of the tube bundle, thetubes 58 are secured together as by a plurality ofwelds 62. The tubes are held inflange 32 in a fluid-tight relation as by brazing. When the tube bundle is assembled into the burner as shown, the interior of tubes communicate through the flange assembly 24-32-36 to theconduit 34 and the interstices communicate with theconduit 44.Passages 57 betweentubes 58adjacent adapter 44 facilitate the flow of the oxidizing fluid in the interstices defined bytubes 58. Theconduit 34 is normally connected to a source of fuel gas such as natural gas and the oxidizingfluid conduit 44 is connected to a source of oxygen. Thewater conduits 46 and 52 are connected to a source of water and a drain area respectively for cooling the burner. As shown in the drawing, the sum of the crosssectional area of the interstices orspaces 60 between the outer surfaces ofadjacent tubes 58 and between the outer surfaces oftubes 58 and the adjacent surface of the burner housing define the cross-sectional area of a fluid passage that cross-sectional area of a second fluid passage can be determined by the sum of the crosssectional area of each of the bores oftubes 58 of the tube bundle.

As shown in FIG. 7, the length-to-diameter ratio of thecombustion chamber 64 is selected for the proper number so as to minimize the noise level of the burner during operation. For example. if the burner is constucted with four tubes (58) and is to be operated at a firing rate of million BTUs per hour, then curve D is used to select the proper length-to-diameter ratio for minimum operating noise level. In this case, the length to-diameter ratio (L/D) would be 1.5. If the burner having four tubes is to be operated at million Btus per hour, then curve B is used to select the proper (L/D) ratio which is also 1.5. It has been found that a preferred burner is constructed with seven tubes and if so constructed curve C of FIG. 7 shows the optimum L/D ratio of 0.6 for minimizing the operating noise level of the burner. Curve A shows the operating noise level for a standard oxy-fuel burner constructed with a single fuel tube and single oxygen tube concentrically positioned within the combustion chamber.

FIG. 8 shows that the preferred ratio of the area of the oxidizing fuel passage A to the area of the fuel gas passage A should be between 0.785 and 1.27. The data for FIGS. 7 and 8 was arrived at by constructing the burner so that the L/D ratios and the A /AG could be varied. The test burner was placed on a horizontal plane with a microphone in a position so that its longitudinal axis was parallel to the axis of the burner at aposition 10 feet from the burner nozzle. Sound equipment sold by General Radio including a model 155 l-C Sound Level Meter, a type 1568 wave analyzer, and a type 1521 graphic level recorder were used. Sound analysis records were made of each test firing recording noise level decibels weighted on the C scale with a sound pressure reference level of 20 micro Newtons per meter square to get frequency from 25 to 25,000 Hz. The equipment was calibrated by General Radio prior to the test program and checked prior to each run with a General Radio sound level calibrator. The data was accumulated and the graphs plotted from the accumulated data.

It is conceivable that the water jacket assembly shown in FIG. 1 could be replaced with a refractory material thereby eliminating the necessity for water cooling and simplifying the overall burner construction.

The overall length of the tube bundle will be dependent upon the length of the burner which is dependent upon the furnace to which the burner will be applied;

however, for most burners the relationships shown in FIGS. 7 and 8 will provide a burner of minimum oper ating noise level. It is the primary object of the tube bundle to completely separate the fuel from the oxygen permitting the two to enter the combustion chamber at the same time. A multiplicity of tubes increases the total length of interface between the fuel and oxygen and the larger the number of tubes the better mixing and the quieter the operation of the burner as illustrated by the curves in FIG. 7.

There is shown in FIG. 4 another embodiment of the present invention with the burner, being generally identified as 63, including a plurality oftubes 82 within the water jacket held together by spacers 83 at thenozzle end 88 ofburner 63 as shown in FIG. 6. The waterjacket tube bundle 82 extends toward thehead 68 ofburner 63 throughflange 76.Tubes 82 are brazed to flange 76 to provide a fluid-tight seal as shown at 77.Tube 78 passes throughflange 76, and is held in fluidtight relation thereto, held in fluid-tight housing section 73 ofburner section 74 and brazed tonozzle ring 86 which in turn is welded to theouter shell 85 ofburner section 84 thus defining a fluid jacket. The fluid jacket has afirst conduit adapter 78 and a second conduit adapter for permitting a cooling fluid to enteradapter 78, flow down throughtubes 82, circulate aroundtubes 82, and contactingring 86, shell and a portion of theburner section 74 and be removed throughadapter 80. This construction of a water jacket greatly increases the ability of the water to cool the burner and provide more efficient operation at elevated temperatures. The burner further includes aflush head 68 and threaded oxidizinggas passage 70 instead of theelbow 34 andconduit adapter 44 respectively of the burner of FIG. 1. Thehead 68 includes flange 71 and both are held to the burner housing 74-84 bybolts 69 andgaskets 72 to insure a fluid-tight seal with thehousing section 73 of the burner shown generally as 63.Burner 63 is made in sections as isburner 10; however, the sections are joined by thepermanent flange 76 instead of thecoupling 16 ofburner 10. The permanent welded structure ofburner 63 minimizes the possibility of fluid leaks due to the working loose of the coupling under severe vibrational loading as is normally associated with high pressure fuel burners. Such a construction also makes fabrication of the burner relatively easy.

Disposed with theburner 63 housing 74-84 is atube bundle 58 constructed in an identical manner to thetube bundle 58 ofburner 10. The bundle is welded on oneend 89 as bywelds 64 and extend through flange 71 to which they are brazed to insure a fluid-tight fit. The space between theend 89 ofbundle 58 and nozzle end 88 ofburner 63 defines acombustion chamber 87. The interior of tubes 58' communicate with a threadedaperture 67 inhead 68 and the interstices between thetubes 58 communicate withpassage 70.

In operation, the burner of FIG. 4 is identical to that of FIG. 1. A source of fuel (natural gas) is connected byaperture 67 to head 68 and a source oxidizing fluid (oxygen) is connected topassage 70. Cooling fluid (water) is connected toadapter 78 and a reservoir or drain connected toadapter 80. The burner is ignited and directed at the material or area being heated.

As shown in FIG. 8, if the oxidizing fluid and fuel connections are reversed so oxidizing fluid is inside the tubes oftube bundle 58, 58' and fuel is in the interstices at low firing rates, such operation provides a lower operating noise level. At normal firing rates (excess of two million BTU/hr.) the A /A relationships approach one another and operating noise level is primarily governed by the combustion chamber L/D ratio as shown in FIG. 7.

It would be possible to operate the burners of the present invention as enriched liquid fuel burners by replacing the center tube ofbundle 58, 58 with a liquid fuel conduit or otherwise introducing liquid fuel into thecombustion chamber 64, 87 for combustion with the oxy-fuel mixture. In order for such a burner to be effective, a nozzle would be required on the delivery end of the liquid fuel conduit to effectively atomize the liquid fuel.

Having thus described my invention what I desire to be secured by Letters Patent of the United States is set forth in the following claims.

I claim:

1. A burner of the oxy-fuel type comprising in combination:

an elongated generally cylindrical housing having an outer wall and an inner wall with internal fluid cooling passages, said housing defining on one end thereof an opening for producing a flame;

means for introducing to and removing fluid from said internal fluid cooling passages;

a plurality of elongated tubes disposed within said housing, defining a bundle compacted by the inner wall of said housing with the axis of each tube generally parallel to the axis of the other tubes, each of said tubes being spaced apart from the other tubes in said bundle and so constructed and arranged to define a first longitudinal fluid passage having a total cross-sectional area comprising the sum of the individual cross-sectional areas defined by the outside surfaces of adjacent tubes and the outside surfaces of said tubes and the adjacent housing surface said passage being coextensive with the tube bundle, a second longitudinal fluid passage having a cross-sectional area defined by the sum of the cross-sectional areas defined by the bore of each tube in said bundle, said bundle being spaced inwardly from the opening in the housing for producing a flame thereby defining a generally cylindrical combustion chamber;

means for introducing a first fluid through the passage defined by the bores of said tubes to said combustion chamber;

means for introducing a second fluid into the passage defined by the outside surfaces of the tubes in the tube bundle for mixing with the first fluid in the combustion chamber to provide a flame directed outwardly of said housing, said first and second fluids being either a fuel or an oxidizing fluid.

2. A burner according to claim. 1 wherein the combustion chamber has a length-to-diameter (L/D) ratio of between 0.4 and 3.0.

3. A burner according toclaim 2 wherein the L/D ratio is less than I.

4. A burner according to claim 1 wherein the first fluid passage is connected to a source of oxidizing fluid and the second passage is connected to a source of fuel and the ratio of the cross-sectional area of the oxidizing fluid passage to the cross-sectional area of the fuel passage is between 0.5 and 1.3.

5. A burner according to claim 1 wherein the housing is made in fluid-tight removable sections for easy replacement of the tubes and combustion chamber.

6. A burner according to claim. I wherein the tube bundle contains between four and seven tubes.

7. A burner according to claim 1 wherein the internal fluid cooling passage is annular in cross-section with a plurality of spaced apart tubes disposed within the annulus for conducting fluid into the annulus, said tubes extending for substantially the length of the passage.

8. A burner of the oxy-fuel type comprising in combination:

a generally cylindrical housing having an outer wall and an inner wall with a fluid-tight closure on a first end with the second end being; open thereby defining a combustion chamber or flame end;

fluid cooling means disposed within said housing for cooling a portion of the housing extending from the second end towards the first end;

means for introducing to and removing fluid from said fluid cooling means;

a plurality of elongated tubes disposed within said housing, defining a bundle compacted by the inner wall of said housing with the axis of each tube generally parallel to the axis of the other tubes and to the axis of the housing, each of said tubes being spaced apart from the other tubes in said bundle and so constructed and arranged to define a first longitudinal fluid passage having a total crosssectional area comprising the sum of the individual cross-sectional areas defined by the outside surfaces of adjacent tubes and the outside surfaces of said tubes and the adjacent housing surface said passage being coextensive with tue tube bundle, a second longitudinal fluid passage having a crosssectional area defined by the sum of the crosssectional areas defined by the bore of each tube in said bundle, said bundle being spaced inwardly from the second end of the housing thereby defining a combustion chamber, said tubes extending through the closure on the first end of said housing;

10. A burner according to claim 8 wherein the length-to-diameter ratio (L/D) of the combustion chamber is less than 1.

11. A burner according to claim 8 wherein the ratio of the cross-sectional area of the oxygen passages to the cross-sectional area of the fuel passage is between 0.3 and 1.5.

12. A burner according to claim 8 wherein the tube bundle contains between four and seven tubes.

* l l l

Claims (12)

1. A burner of the oxy-fuel type comprising in combination: an elongated generally cylindrical housing having an outer wall and an inner wall with internal fluid cooling passages, said housing defining on one end thereof an opening for producing a flame; means for introducing to and removing fluid from said internal fluid cooling passages; a plurality of elongated tubes disposed within said housing, defining a bundle compacted by the inner wall of said housing with the axis of each tube generally parallel to the axis of the other tubes, each of said tubes being spaced apart from the other tubes in said bundle and so constructed and arranged to define a first longitudinal fluid passage having a total crosssectional area comprising the sum of the individual crosssectional areas defined by the outside surfaces of adjacent tubes and the outside surfaces of said tubes and the adjacent housing surface said passage being coextensive with the tube bundle, a second longitudinal fluid passage having a crosssectional area defined by the sum of the cross-sectional areas defined by the bore of each tube in said bundle, said bundle being spaced inwardly from the opening in the housing for producing a flame thereby defining a generally cylindrical combustion chamber; means for introducing a first fluid through the passage defined by the bores of said tubes to said combustion chamber; means for introducing a second fluid into the passage defined by the outside surfaces of the tubes in the tube bundle for mixing with the first fluid in the combustion chamber to provide a flame directed outwardly of said housing, said first and second fluids being either a fuel or an oxidizing fluid.

2. A burner according to claim 1 wherein the combustion chamber has a length-to-diameter (L/D) ratio of between 0.4 and 3.0.

3. A burner according to claim 2 wherein the L/D ratio is less than 1.

4. A burner according to claim 1 wherein the first fluid passage is connected to a source of oxidizing fluid and the second passage is connected to a source of fuel and the ratio of the cross-sectional area of the oxidizing fluid passage to the cross-sectional area of the fuel passage is between 0.5 and 1.3.

5. A burner according to claim 1 wherein the housing is made in fluid-tight removable sections for easy replacement of the tubes and combustion chamber.

6. A burner according to claim 1 wherein the tube bundle contains between four and seven tubes.

7. A burner according to claim 1 wherein the internal fluid cooling passage is annular in cross-section with a plurality of spaced apart tubes disposed within the annulus for conducTing fluid into the annulus, said tubes extending for substantially the length of the passage.

8. A burner of the oxy-fuel type comprising in combination: a generally cylindrical housing having an outer wall and an inner wall with a fluid-tight closure on a first end with the second end being open thereby defining a combustion chamber or flame end; fluid cooling means disposed within said housing for cooling a portion of the housing extending from the second end towards the first end; means for introducing to and removing fluid from said fluid cooling means; a plurality of elongated tubes disposed within said housing, defining a bundle compacted by the inner wall of said housing with the axis of each tube generally parallel to the axis of the other tubes and to the axis of the housing, each of said tubes being spaced apart from the other tubes in said bundle and so constructed and arranged to define a first longitudinal fluid passage having a total cross-sectional area comprising the sum of the individual cross-sectional areas defined by the outside surfaces of adjacent tubes and the outside surfaces of said tubes and the adjacent housing surface said passage being coextensive with tue tube bundle, a second longitudinal fluid passage having a cross-sectional area defined by the sum of the cross-sectional areas defined by the bore of each tube in said bundle, said bundle being spaced inwardly from the second end of the housing thereby defining a combustion chamber, said tubes extending through the closure on the first end of said housing; means for introducing gaseous fuel under pressure inside said tubes; means for introducing oxygen under pressure into the interstices defined by the tube bundle for mixing with the fuel in the combustion chamber to provide a flame directed outwardly of said housing.

9. A burner according to claim 8 wherein the length-to-diameter (L/D) ratio of the combustion chamber is between 0.4 and 3.0.

10. A burner according to claim 8 wherein the length-to-diameter ratio (L/D) of the combustion chamber is less than 1.

11. A burner according to claim 8 wherein the ratio of the cross-sectional area of the oxygen passages to the cross-sectional area of the fuel passage is between 0.3 and 1.5.

12. A burner according to claim 8 wherein the tube bundle contains between four and seven tubes.

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