CA1245543A - Low no.sub.x formation fuel burning methods and apparatus - Google Patents
Low no.sub.x formation fuel burning methods and apparatusInfo
- Publication number
- CA1245543A CA1245543A CA000486490A CA486490A CA1245543A CA 1245543 A CA1245543 A CA 1245543A CA 000486490 A CA000486490 A CA 000486490A CA 486490 A CA486490 A CA 486490A CA 1245543 A CA1245543 A CA 1245543A
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- Canada
- Prior art keywords
- fuel
- air
- nozzle
- orifices
- zone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- 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
- F23D14/48—Nozzles
- F23D14/58—Nozzles characterised by the shape or arrangement of the outlet or outlets from the nozzle, e.g. of annular configuration
-
- 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
- F23D14/20—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
Abstract
Abstract Of The Disclosure Methods and apparatus for combusting fuel-air mixtures while inhibiting the formation of nitrogen oxides are provided. The fuel is discharged from one or more nozzles disposed within a housing, air is caused to flow into the housing whereby it mixes with the fuel and the resulting fuel-air mixture is ignited and combusted. The nozzle or nozzles each include one or more ignition orifices for discharging a first portion of fuel in an ignition zone, one or more primary combustion orifices for discharging a second portion of fuel in a primary combustion zone containing excess air and one or more secondary combustion orifices for discharging the remaining portion of fuel within and downstream of the primary combustion zone whereby the fuel is burned in a secondary combustion zone substantially shielded from direct contact with incoming air by the primary combustion zone.
Description
~1~4~S~3 H-TIP
LOW NOX FORr~ATION FU~L BURNING MErr~ODS AND APPARATUS
Background of the Invention 1. Fie d of the Invention The present invention relates yenerally to methods and burner apparatus for combusting fuel-air mixture.s, and more particularly, to rnethods and burner apparatus for combusting fuel and air while inhibiting the Eormation of nitrogen oxides.
LOW NOX FORr~ATION FU~L BURNING MErr~ODS AND APPARATUS
Background of the Invention 1. Fie d of the Invention The present invention relates yenerally to methods and burner apparatus for combusting fuel-air mixture.s, and more particularly, to rnethods and burner apparatus for combusting fuel and air while inhibiting the Eormation of nitrogen oxides.
2. Description of the Prior Art A variety of rnethods and burner apparatus for combusting fuel and air ~ixtures have been developed and utilized heretofore. Such burner apparatus are used in a great variety of applications where fuel is co~busted to provide heat for a particular purpose, e.g., heating process s-treams, generating steam, drying materials, etc. The burning of fuels, however, can result in the formation of nitrogen oxides (NOX) whicn when released to the a-tmosphere constitute pollutants. As a result, environ~ental emission standards have been imposed by various governmental authorities and agencies which require the inhibition of the formation of nitrogen oxides during fuel-air combustion.
Various methods and burner apparatus for combusting fuel-air mixtures while suppressing the formation of nitrogen oxides have been developed. For example, United States Patent No. 4,004,875 issued January 25, 1977~ is directed to a low NOX burner wherein the fuel is first burned in a zone in which there is less than a stoichiometric concentration of air thereby producing a , ~ .
, ~
~4~
reducing environ-rnent that suppresses NOx formation wit~ the deficiency in air being made up in a subsequent burning ~one.
Fuel staging has atso been employed Eor suppressing NOx formation. That is, a portion of the uel is burned in a first zone with air bein~ supplied at a rate in excess of the stolchiometric rate required with the remaining fuel being burned in a second zone. The presence of excess air in the first zone lowers the temperatura o~ the combustion reaction and suppresses NOx formation. The fuel in the second zone reacts with the excess oxygen resulting from the co~bustion in the first zone and is diluted with surrounding co~bustion gases which lowers the combustion reaction temperature and suppresses the formation of NOx in the second zone. A multi-stage combustion method of -this type is described in United States Patent No. 4,395,223 issued 3uly 26, 1983.
While methods and burner apparatus u-tili~ing staged ~ombustion have been successful in reducing NOx e~nissions heretofore, the methods have required elaborate burner apparatus to carry out, i.e., apparatus including a plurality of fuel nozzles and/or complex air or recycle gas distribution systems making the apparatus expensive to install and operate.
By the presen-t invention improved methods and burner a~paratus for combusting fuel-air mixtures while inhibiting the formation of nitroyen oxides are provided which are simple and inexpensive as compared to prior art methods and apparatus.
lZ45~
Summary of the Invention Methods of combusting fuel-air mixtures whereby the Eormation of nitrogen oxides is inhibited are provided. In accordance with the methods, fuel is discharged ~rom a nozzle disposed within a burner housin~, air is'introduced into the housing which is mixed with the fuel and the resulting fuel-air rnixture is ignited and cornbusted. A
first portion of the fuel is discharged from the nozzle through one or more orifices therein whereby the fuel mixes with air and provides an igni-tion zone adjacent the nozzle.
A second portion of the fuel is discharged Erom the nozzle by way of one or more additional orifices whereby the second portion of fuel is distributed in a turbulent pattern which exposes the uel to a quantity of air in excess of that required Eor the stoichiometric burning thereof and causes the fuel to burn in a primary col~bustion zone. The remaining portion of the fuel is dlscharged froln the nozzle by way of one or more additional orifices whereby the fuel is distributed wit`nin and downstream of the primary combus-tion zone. The remaining portion of fuel is mixed withexcess air from the primary cornbustion zone and combustion products and is burned in a secondary co~bustion zone substantially shielded from direct contact with incoming air by the primary combustion zone. ~urner apparatus for carrying Ollt the methods are also provided.
It is, therefore, a general object of the present invention to provide low NOX for~ation fuel burning ~nethods and apparatus.
A further object oE the present invention is the provision of improved me-thods oE cornbusting fuel-air ~Z455~
mixtures whereby the Eor~ation of nitroyen oxides is inhibited which can be carried Ollt in relatively simple and inexpensive burner apparatus.
Another vbject of the present invention is the provision of i~proved burner apparatus for cornbusting fuel-air mixture~s while inhibiting the for~ation of nitroyen oxides.
other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a raading of the description of preferred embodiments which follows when taken in conjunction with the accompanying drawings.
Brief Description Of The Drawings FIGURE l is a slde cross-sectional view of the low NOX for~ation fuel burning apparatus of the present invention.
FIGURE 2 is a top plan view of the apparatus of FIGURE
1.
FIGURE 3 is an enlarged partly sectional view of a portion of the apparatus of FIGU~E 1 includin-~ the fuel discharge nozæle thereof.
FIGURE 4 is a top plan view of the apparatus of FIGVRE
Various methods and burner apparatus for combusting fuel-air mixtures while suppressing the formation of nitrogen oxides have been developed. For example, United States Patent No. 4,004,875 issued January 25, 1977~ is directed to a low NOX burner wherein the fuel is first burned in a zone in which there is less than a stoichiometric concentration of air thereby producing a , ~ .
, ~
~4~
reducing environ-rnent that suppresses NOx formation wit~ the deficiency in air being made up in a subsequent burning ~one.
Fuel staging has atso been employed Eor suppressing NOx formation. That is, a portion of the uel is burned in a first zone with air bein~ supplied at a rate in excess of the stolchiometric rate required with the remaining fuel being burned in a second zone. The presence of excess air in the first zone lowers the temperatura o~ the combustion reaction and suppresses NOx formation. The fuel in the second zone reacts with the excess oxygen resulting from the co~bustion in the first zone and is diluted with surrounding co~bustion gases which lowers the combustion reaction temperature and suppresses the formation of NOx in the second zone. A multi-stage combustion method of -this type is described in United States Patent No. 4,395,223 issued 3uly 26, 1983.
While methods and burner apparatus u-tili~ing staged ~ombustion have been successful in reducing NOx e~nissions heretofore, the methods have required elaborate burner apparatus to carry out, i.e., apparatus including a plurality of fuel nozzles and/or complex air or recycle gas distribution systems making the apparatus expensive to install and operate.
By the presen-t invention improved methods and burner a~paratus for combusting fuel-air mixtures while inhibiting the formation of nitroyen oxides are provided which are simple and inexpensive as compared to prior art methods and apparatus.
lZ45~
Summary of the Invention Methods of combusting fuel-air mixtures whereby the Eormation of nitrogen oxides is inhibited are provided. In accordance with the methods, fuel is discharged ~rom a nozzle disposed within a burner housin~, air is'introduced into the housing which is mixed with the fuel and the resulting fuel-air rnixture is ignited and cornbusted. A
first portion of the fuel is discharged from the nozzle through one or more orifices therein whereby the fuel mixes with air and provides an igni-tion zone adjacent the nozzle.
A second portion of the fuel is discharged Erom the nozzle by way of one or more additional orifices whereby the second portion of fuel is distributed in a turbulent pattern which exposes the uel to a quantity of air in excess of that required Eor the stoichiometric burning thereof and causes the fuel to burn in a primary col~bustion zone. The remaining portion of the fuel is dlscharged froln the nozzle by way of one or more additional orifices whereby the fuel is distributed wit`nin and downstream of the primary combus-tion zone. The remaining portion of fuel is mixed withexcess air from the primary cornbustion zone and combustion products and is burned in a secondary co~bustion zone substantially shielded from direct contact with incoming air by the primary combustion zone. ~urner apparatus for carrying Ollt the methods are also provided.
It is, therefore, a general object of the present invention to provide low NOX for~ation fuel burning ~nethods and apparatus.
A further object oE the present invention is the provision of improved me-thods oE cornbusting fuel-air ~Z455~
mixtures whereby the Eor~ation of nitroyen oxides is inhibited which can be carried Ollt in relatively simple and inexpensive burner apparatus.
Another vbject of the present invention is the provision of i~proved burner apparatus for cornbusting fuel-air mixture~s while inhibiting the for~ation of nitroyen oxides.
other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a raading of the description of preferred embodiments which follows when taken in conjunction with the accompanying drawings.
Brief Description Of The Drawings FIGURE l is a slde cross-sectional view of the low NOX for~ation fuel burning apparatus of the present invention.
FIGURE 2 is a top plan view of the apparatus of FIGURE
1.
FIGURE 3 is an enlarged partly sectional view of a portion of the apparatus of FIGU~E 1 includin-~ the fuel discharge nozæle thereof.
FIGURE 4 is a top plan view of the apparatus of FIGVRE
3.
FIGURE 5 is a side cross-sectional view of the burner apparatus of FIGURE 1 illustrating the operation of the apparatus.
~escription Of Preferred Embodiments Referring now to the drawings and particularly to FIGI]RES l and 2, a burner apparatus of the present invention ~2~s.~3 is illustrated and generally designated by the numeral lO.
The burner apparatus lO is shown connected in an c~pening 1~
provided in the floor or wall 12 of a furnace chamber such as the furnace chamber of a process heater containing heat S exchange tubes or a steam generator. The burner apparatus lO is designecl Eor use in applications where gaseous fuels such as hydrocarbon gases are combusted. However, it will be appreciated by those skilled in the art that burner apparatus includin~ the present invention can take a variety of forms.
The burner lO includes a housin~ which is comprised of an external cylindrical ~ousing member 16 attached over the opening 14 in the wall 12, such as by a plurality of bolt members 18, and a heat resistant me~ber 20 formed of refractory material mounted within the furnace cha~nber defined by the wall 12. The interior oE the wall 12 includes an insulating layer of refractory material 22 in which an opening is formed for receiviny the member 20 oE
the burner lO. The member 20 can he attached to the wall 12 and/or refractory material 22 oE the furnace chamber as illustrated or it can be attached to the cylindrical housing member 16 in any convenient manner.
The housing member 16 functions as an air re~ister, and for this purpose, includes a plurality of air inlet openin~s 26 disposed in and around the sides thereof. ~ wall 24 closes the end of the housing member 16 and a cylindrical damper 28 is rotatably positioned over the housing member.
The damper 28 includes air openings (not shown) therein complementary to the air openings 26 in the housing member 30 15. A handle 30 is attached to the damper 28 so that the
FIGURE 5 is a side cross-sectional view of the burner apparatus of FIGURE 1 illustrating the operation of the apparatus.
~escription Of Preferred Embodiments Referring now to the drawings and particularly to FIGI]RES l and 2, a burner apparatus of the present invention ~2~s.~3 is illustrated and generally designated by the numeral lO.
The burner apparatus lO is shown connected in an c~pening 1~
provided in the floor or wall 12 of a furnace chamber such as the furnace chamber of a process heater containing heat S exchange tubes or a steam generator. The burner apparatus lO is designecl Eor use in applications where gaseous fuels such as hydrocarbon gases are combusted. However, it will be appreciated by those skilled in the art that burner apparatus includin~ the present invention can take a variety of forms.
The burner lO includes a housin~ which is comprised of an external cylindrical ~ousing member 16 attached over the opening 14 in the wall 12, such as by a plurality of bolt members 18, and a heat resistant me~ber 20 formed of refractory material mounted within the furnace cha~nber defined by the wall 12. The interior oE the wall 12 includes an insulating layer of refractory material 22 in which an opening is formed for receiviny the member 20 oE
the burner lO. The member 20 can he attached to the wall 12 and/or refractory material 22 oE the furnace chamber as illustrated or it can be attached to the cylindrical housing member 16 in any convenient manner.
The housing member 16 functions as an air re~ister, and for this purpose, includes a plurality of air inlet openin~s 26 disposed in and around the sides thereof. ~ wall 24 closes the end of the housing member 16 and a cylindrical damper 28 is rotatably positioned over the housing member.
The damper 28 includes air openings (not shown) therein complementary to the air openings 26 in the housing member 30 15. A handle 30 is attached to the damper 28 so that the
4~ 3 damper can be rotated be-tween a position whereby the openings 26 are closed by solid portions of the damper 28 and a position ~hereby the openings in the damper 28 are in reyistration with the openlngs 26 to provide full air flow as shown in FIGURE 1.
~ guide tube 32 is disposed coa~ially within the cylindrical housing member 16, the outer end of which is riyidly attached throuf~h an opening in the wall 24, such as by welding. The inner end of the guide tube 32 has a shieldin~ cone 34 attached thereto. A fuel supply conduit 36 extends through the guide tube 32 and has a fuel discharge nozzle 38 connected at the inner end thereof. The exterior end of the conduit 36 is threaded for connection to a source of fuel and the condui-t 36 is sealingly at-tached to a plate 39 which is in turn removably connected by means of bolt members 40 to the wall 24.
A pilot 42 is provided for igniting fuel discharged fro~
the noæzle 38 and is connected to a supply conduit 44 which in turn extends throu~h an opening in the wall 24 and a re~ovable closure member 46 connected thereto. The outer end of the su~ply conduit 44 is connected to a pilot fuel-air mixer 48 which is in turn adapted for connection to a source of pilot fuel.
Referring now to FIG~RES 3 and 4, the Euel dlscharge noz21e 38, shielding cone 34 and related structure are illustrated in detail. The shieldin.~ cone 34 is dish-shaped and includes a plurality of openin,ls 50 formed therein for allowing the passage oE a limited amount oE air therethrough. The shielding cone 3~ functions to create a protected space adjacent the nozzle 38 when incoming air is ~:4~i5~3 flowing in the direction indicated by the arrow 52 of FIGURE
3~ As will be understood, the creation of a pro-tected space adjacent the nozzle 38 can be brought about by various types and shapes of apparatus other than the shielding cone 34.
The nozzle 38 extends through a central opening in the shielding cone 34 and includes an end wall 54 which contains a plurality of Euel discharge orifices. More particularly, the wall portion 54 of the nozzle 38 includes a first set o~
one or more orifices 56 disposed therein. When more than one orifice 56 are utilized, they preferably all are the same size and are positioned in equally spaced relationship around the nozzle 38 in a plane preferably perpendicular to the a~is of -the nozzle 38, i.e., the angle designated by the letter "c" on FIGU~E 3 is 2referably 90. The axis of the lS nozzle 38 is parallel to the a~is of the housing member 16 whereby the axes of the orifices 56 lie in a plane substantially perpendicular to the direction of air flow through the housin~ meTnber 16. The first set of orifices 56 discharge a first portion of the fuel supplied to the nozzle 38 which mixes with a 2ortion of the incoming air and provides an ignition zone adjacent the nozzle 38 as will be described further hereinbelow. The shielding cone 3~
provides a protected space adjacent the nozzle 38 which prevents the i~nition zone frorn being moved away from the nozzle 38, i.e., the shielding cone retains an ignition flame adjacent the nozzle 38.
A second set of one or ~ore orifices 58 is disposed in the wall portion 54 of -the nozzle 38. When more than one orifice 58 are utili2ed, they preferably are all of the same size and are positioned in equally spaced relationship ~LZ4~43 around the wall 54 interiorly of and above the iynition orifices 56. The axes of the oriEices 58 are also preferably inclined in the direction of flow of air at an angle in the range of from abou-t 15 to about 70 therewith, i.e., the axes of -the oriEices 58 are all preferably positioned at the same angle with respect to the axis of the nozzle 38 (the angle designated by the letter "b" in FIGURE
3) which is in the range given above. The second set of orifices 58 discharge a second portion of the fuel supplied to the nozzle 38 which is distributed in a turbulent outwardly flaring pattern. The second portion of fuel mixes with the reMaining incoming air -~hich is in excess of that required for the stoichiometric burning thereof and burns in a primary combustion zone.
~ third set of one or ~ore oriEices 60 is disposed in the wall portion 54 of the nozz~e 38 interiorly of and above the primary combustion oriEices 58. Like the oriEices 56 and 58, when more than one orifice 60 are utilized, they are preferably all of -the same size and are positioned in spaced relationship around the nozzle 38. The axes of the oriEices 60 can be parallel to the axis of the noæzle 38 and to the direction of air flow, or, as shown in FIGURE 3, the axes of the orifices 60 can be inclined at an anyle in the range of from about 1 to about 30 therewith (the anyle "a" shown on FIGURE 3). It should be noted that anyle "a" can be about equal to or less than the angle "b", but should not be greater than the anyle "b".
The orifices 60 discharge the re~aining portion of fuel supplied to the nozzle 38 therefrom whereby substantially all of the remaining portion of Euel is burned in a ~Z~15S~3 secondary combustion zone within and downstream of the primary combustlon zone created by the discharge of the second portion of fuel from the orifices 58.
Referring now to FIGURE 5, :Ln operation of the burner appara-tus 10, fuel under pressure, i.e., a pressure generally in the range of from about about 3 to about 30 psig., is supplied to the condui-t 36. Pilot fuel at a pressure in the range of from about 3 to about 15 psig. is supplied to the air mixer 4~. The pilot fuel is mixed wi-th air while flowing through the mixer 48 and the resul-ting fuel-air mixture is discharged Erorn the pilot 42, ignited and burned. The flame from tAe pilot functions to ignite -the fuel discharged from the nozzle 38. However, it is to be noted that other ignition means can be utilized and the use of a pilot burner is optional.
The pressurized fuel suppliad to the condui-t 36 flows to the nozzle 38 connected thereto and is discharged in-to the furnace chamber through the orifices 56, 58 and 60 therein.
The first set of orifices, i.e., the ignition orifices 56, are of a size and/or number whereby the first portion of fuel discharged therethrough is a rate in the range of from about 1~ to about 25~ of the total rate of fuel discharged from the nozzle 38. Such portion of the fuel mixes with air in the protected space adjacent the nozzle 38, is ignited by the flame frorn the pilot 42 or other means and burns in an ignition zone 62 adjacent the shieldiny cone 34 and nozzle 38.
The second set of orifices, i.e., the primary co~bus-tion orifices 58, are of a size and/or number such that a second portion of fuel is discharged therethrough at a rate in the S5~3 ran~e o~ from about 1~ to about 60~ of the total rate o:E
fuel discharged from the nozzle 38. The second portion of fuel i9 dis-tributed in an outwardly Elarin~ pattern from the nozzle 38 in a turbulent manner which causes the fuel to mix with air flowing into the housing of the burner 10 by way of the openings 26 in the housing rnember 16 thereoE. The rate oE air flowing into the burner 10 is adjusted by adjusting the position of the damper 28 on the housin3 merrlber 16 whereby the total amoun-t of air is substantially equal to or greater than that required for the s-toichiometric burning of the total rate of fuel discharged from the nozzle 38. The second portion of fuel and air mixture produced is combusted in a primary combustion zone 64 which flares outwardly from the nozzla 38. Because the second portion of fuel is mixed with air in excess of that required for the stoichio-metric burning of the fuel, the temperature in the primary corabustion zone 64 is lowered and the formation of NO~ in the primary co(nbustion zone is inhibited.
The remaining porton of the fuel supplied to the nozzle 3~ is dischar~ed therefrom by way of the third set of orifices therein, i.e., the secondary combustion ori-fices 60. The portion of the fuel discharged through the orifices is distributed wlthin and downstream of the primary combustion zone 64 into a secondary cornbustion zone 66 which is substantially shielded from direct contact with inco-ming air by the primary combustion zone 6~. The fuel in the secondary combustion zone is mixed with air from the primary combustion zone which is diluted with combustion products from the primary combus-tion zone~
Thus, because the remaining portion of fuel discharged through the secondary cornbustion orifices 60 is burned in a ~L2~ 3 secondary combustion zone 6~ within and downstream of the primary combustion zone 64, and because the air mixed with such remaining portion of fuel i5 diluted with combustion producks, the combustion -takes place at a relatively low S temperature whereby the formation of NOX is inhibited.
The method of the present invention whereby fuel can be discharged frorn a single nozzle or two or more nozzles and burned wlth low NOX formation is comprised oE the steps of discharging a first portion of euel fro~ each nozzle through one or more orifices, or a set of orifices therein, whereby the Euel mixes with air and provides an ignition zone adjacent the nozzle; discharging a second portion of the Euel through one or more additional ori~ices, or a second set of oriEices therein, whereby the second portion of fuel is distributed ~in a turbulent pattern which causes the fuel to mix wi~h a rate of air in excess of tha-t required for the stoichio~etric burnin~ thereof and to burn in a primary combustion zone; and discharging the remaining portion of the fuel from the nozzle through one or more additional orifices, or a third set of orifices therein, whereby the relnaining portion of the fuel is distributed within and downstream of the primary cornbustion zone wherein i-t is mixed with air frorn the primary combustion zone which is diluted with combustion products from the primary cornbustion zone. The resulting mixture of fuel and combustion product diluted air is burned in the secondary cornbustion zone.
As men-tioned above, because the combuskion in the primary cornbustion zone takes place in e~cess air, -the flame temperature in such zone is lowered whereby the formation of NOX is inhibited. Combustion in the secondary combustion ~2~5~3 zone is delayed because the secondary combustion zone is shielded by the pri~ary zone from direct contact with incoming air. This delay in the mixing of the fuel and air allows for dilution of the air with corQbustion products from the primary combustion zons, resulting in a lower co~bustion temperature which inhihits the for~ation of NOX in the secondary combustion zone.
While the present invention has been described as it relates to a natural draEt burner apparatus, it is to be understood that the inven-tion is applicable to a wide variety of burner designs, including those utilizing forced draft. In additionr more than one fuel discharge nozzle of the presen-t invention can be utilized in a single burner apparatus, as for example, the burner apparatus disclosed in 15 U.S~ Patent No. 3,033,273 issued on r~ay 8, 1362. Further, the fuel discharge nozzls and shielding cone utilized in burners in accordance with this invention can take various forms and shapes so long as the functional li~itations described above are ~et thereby.
In order to facilitate a clear understanding of th~
method and apparatus of the present invention, the following example is ~iven.
Example A burner apparatus 10 designed for a heat release oE
6,000,000 BTU/hr by burning natural gas having a calorific value of 930 BTU/SC~ is firsd into a furnace char~ber. The nozzle 38 includes a first set of 6 orifices 56 of 0.0625 inch diameter, a second set of 4 orifices 58 of 0.1405 inch 30 dia~eter and a third set of 4 orifices 60 of 0.1875 inch ~s~
dia~eter. The axes of the oriEices 56 are at an angle of 90 with the axis of the nozzle 38, the axes of the orifices 58 are at an angle of 4~ with the axis of the nozzle 38 and the axes of the oriEices 60 are at an angle of 10 therewith.
The fuel is supplied -to the nozzle 3~ at a pressure oE
about 15 psiq. and at a rate of about 6452 SCF/hr. The first portion o fuel discharged through the ignition nozzles 56 is at a rate of about 596 ~CF/hr., the second portion of fuel discharged through the primary co~bus-tion orifices 5~ is at a rate of about 1986 SCF/hr. and the remaining portion of fuel discharged through the secondary coinbustion oriEices 60 is at a rate oE about 3870 SC~/hr.
The discharged Euel is co~bined witn air in the burner apparatus 10 and burned whereby a heat release in the furnace chamber of about 6,000,~00 ~TU/hr. is realized. ~he stack emissions from the simulated furnace chamber contain an NOX concentration of less than about 40 pprn. A
conventional burner including a conven-tional nozzle fired in the furnace chamber in the same manner and under the same conditions creates stack emissions containing an NOX concentration of more thar- about 70 ppm.
Thus, the present invention is well adapted to carry out the objects and attain the advantages mentioned as well as those inherent therein. While ~resently preferred embodiments of the invention have been described herein for purposes oE this disclosure, numerous changes in the construction of parts and in the arrangenent of parts and steps will suggest themselves to those skilled in the art, ~2~S~
which changes are encompassed wi-thin the spiri-t of this invention as defined by the appended claims.
~hat is claimed i5:
n
~ guide tube 32 is disposed coa~ially within the cylindrical housing member 16, the outer end of which is riyidly attached throuf~h an opening in the wall 24, such as by welding. The inner end of the guide tube 32 has a shieldin~ cone 34 attached thereto. A fuel supply conduit 36 extends through the guide tube 32 and has a fuel discharge nozzle 38 connected at the inner end thereof. The exterior end of the conduit 36 is threaded for connection to a source of fuel and the condui-t 36 is sealingly at-tached to a plate 39 which is in turn removably connected by means of bolt members 40 to the wall 24.
A pilot 42 is provided for igniting fuel discharged fro~
the noæzle 38 and is connected to a supply conduit 44 which in turn extends throu~h an opening in the wall 24 and a re~ovable closure member 46 connected thereto. The outer end of the su~ply conduit 44 is connected to a pilot fuel-air mixer 48 which is in turn adapted for connection to a source of pilot fuel.
Referring now to FIG~RES 3 and 4, the Euel dlscharge noz21e 38, shielding cone 34 and related structure are illustrated in detail. The shieldin.~ cone 34 is dish-shaped and includes a plurality of openin,ls 50 formed therein for allowing the passage oE a limited amount oE air therethrough. The shielding cone 3~ functions to create a protected space adjacent the nozzle 38 when incoming air is ~:4~i5~3 flowing in the direction indicated by the arrow 52 of FIGURE
3~ As will be understood, the creation of a pro-tected space adjacent the nozzle 38 can be brought about by various types and shapes of apparatus other than the shielding cone 34.
The nozzle 38 extends through a central opening in the shielding cone 34 and includes an end wall 54 which contains a plurality of Euel discharge orifices. More particularly, the wall portion 54 of the nozzle 38 includes a first set o~
one or more orifices 56 disposed therein. When more than one orifice 56 are utilized, they preferably all are the same size and are positioned in equally spaced relationship around the nozzle 38 in a plane preferably perpendicular to the a~is of -the nozzle 38, i.e., the angle designated by the letter "c" on FIGU~E 3 is 2referably 90. The axis of the lS nozzle 38 is parallel to the a~is of the housing member 16 whereby the axes of the orifices 56 lie in a plane substantially perpendicular to the direction of air flow through the housin~ meTnber 16. The first set of orifices 56 discharge a first portion of the fuel supplied to the nozzle 38 which mixes with a 2ortion of the incoming air and provides an ignition zone adjacent the nozzle 38 as will be described further hereinbelow. The shielding cone 3~
provides a protected space adjacent the nozzle 38 which prevents the i~nition zone frorn being moved away from the nozzle 38, i.e., the shielding cone retains an ignition flame adjacent the nozzle 38.
A second set of one or ~ore orifices 58 is disposed in the wall portion 54 of -the nozzle 38. When more than one orifice 58 are utili2ed, they preferably are all of the same size and are positioned in equally spaced relationship ~LZ4~43 around the wall 54 interiorly of and above the iynition orifices 56. The axes of the oriEices 58 are also preferably inclined in the direction of flow of air at an angle in the range of from abou-t 15 to about 70 therewith, i.e., the axes of -the oriEices 58 are all preferably positioned at the same angle with respect to the axis of the nozzle 38 (the angle designated by the letter "b" in FIGURE
3) which is in the range given above. The second set of orifices 58 discharge a second portion of the fuel supplied to the nozzle 38 which is distributed in a turbulent outwardly flaring pattern. The second portion of fuel mixes with the reMaining incoming air -~hich is in excess of that required for the stoichiometric burning thereof and burns in a primary combustion zone.
~ third set of one or ~ore oriEices 60 is disposed in the wall portion 54 of the nozz~e 38 interiorly of and above the primary combustion oriEices 58. Like the oriEices 56 and 58, when more than one orifice 60 are utilized, they are preferably all of -the same size and are positioned in spaced relationship around the nozzle 38. The axes of the oriEices 60 can be parallel to the axis of the noæzle 38 and to the direction of air flow, or, as shown in FIGURE 3, the axes of the orifices 60 can be inclined at an anyle in the range of from about 1 to about 30 therewith (the anyle "a" shown on FIGURE 3). It should be noted that anyle "a" can be about equal to or less than the angle "b", but should not be greater than the anyle "b".
The orifices 60 discharge the re~aining portion of fuel supplied to the nozzle 38 therefrom whereby substantially all of the remaining portion of Euel is burned in a ~Z~15S~3 secondary combustion zone within and downstream of the primary combustlon zone created by the discharge of the second portion of fuel from the orifices 58.
Referring now to FIGURE 5, :Ln operation of the burner appara-tus 10, fuel under pressure, i.e., a pressure generally in the range of from about about 3 to about 30 psig., is supplied to the condui-t 36. Pilot fuel at a pressure in the range of from about 3 to about 15 psig. is supplied to the air mixer 4~. The pilot fuel is mixed wi-th air while flowing through the mixer 48 and the resul-ting fuel-air mixture is discharged Erorn the pilot 42, ignited and burned. The flame from tAe pilot functions to ignite -the fuel discharged from the nozzle 38. However, it is to be noted that other ignition means can be utilized and the use of a pilot burner is optional.
The pressurized fuel suppliad to the condui-t 36 flows to the nozzle 38 connected thereto and is discharged in-to the furnace chamber through the orifices 56, 58 and 60 therein.
The first set of orifices, i.e., the ignition orifices 56, are of a size and/or number whereby the first portion of fuel discharged therethrough is a rate in the range of from about 1~ to about 25~ of the total rate of fuel discharged from the nozzle 38. Such portion of the fuel mixes with air in the protected space adjacent the nozzle 38, is ignited by the flame frorn the pilot 42 or other means and burns in an ignition zone 62 adjacent the shieldiny cone 34 and nozzle 38.
The second set of orifices, i.e., the primary co~bus-tion orifices 58, are of a size and/or number such that a second portion of fuel is discharged therethrough at a rate in the S5~3 ran~e o~ from about 1~ to about 60~ of the total rate o:E
fuel discharged from the nozzle 38. The second portion of fuel i9 dis-tributed in an outwardly Elarin~ pattern from the nozzle 38 in a turbulent manner which causes the fuel to mix with air flowing into the housing of the burner 10 by way of the openings 26 in the housing rnember 16 thereoE. The rate oE air flowing into the burner 10 is adjusted by adjusting the position of the damper 28 on the housin3 merrlber 16 whereby the total amoun-t of air is substantially equal to or greater than that required for the s-toichiometric burning of the total rate of fuel discharged from the nozzle 38. The second portion of fuel and air mixture produced is combusted in a primary combustion zone 64 which flares outwardly from the nozzla 38. Because the second portion of fuel is mixed with air in excess of that required for the stoichio-metric burning of the fuel, the temperature in the primary corabustion zone 64 is lowered and the formation of NO~ in the primary co(nbustion zone is inhibited.
The remaining porton of the fuel supplied to the nozzle 3~ is dischar~ed therefrom by way of the third set of orifices therein, i.e., the secondary combustion ori-fices 60. The portion of the fuel discharged through the orifices is distributed wlthin and downstream of the primary combustion zone 64 into a secondary cornbustion zone 66 which is substantially shielded from direct contact with inco-ming air by the primary combustion zone 6~. The fuel in the secondary combustion zone is mixed with air from the primary combustion zone which is diluted with combustion products from the primary combus-tion zone~
Thus, because the remaining portion of fuel discharged through the secondary cornbustion orifices 60 is burned in a ~L2~ 3 secondary combustion zone 6~ within and downstream of the primary combustion zone 64, and because the air mixed with such remaining portion of fuel i5 diluted with combustion producks, the combustion -takes place at a relatively low S temperature whereby the formation of NOX is inhibited.
The method of the present invention whereby fuel can be discharged frorn a single nozzle or two or more nozzles and burned wlth low NOX formation is comprised oE the steps of discharging a first portion of euel fro~ each nozzle through one or more orifices, or a set of orifices therein, whereby the Euel mixes with air and provides an ignition zone adjacent the nozzle; discharging a second portion of the Euel through one or more additional ori~ices, or a second set of oriEices therein, whereby the second portion of fuel is distributed ~in a turbulent pattern which causes the fuel to mix wi~h a rate of air in excess of tha-t required for the stoichio~etric burnin~ thereof and to burn in a primary combustion zone; and discharging the remaining portion of the fuel from the nozzle through one or more additional orifices, or a third set of orifices therein, whereby the relnaining portion of the fuel is distributed within and downstream of the primary cornbustion zone wherein i-t is mixed with air frorn the primary combustion zone which is diluted with combustion products from the primary cornbustion zone. The resulting mixture of fuel and combustion product diluted air is burned in the secondary cornbustion zone.
As men-tioned above, because the combuskion in the primary cornbustion zone takes place in e~cess air, -the flame temperature in such zone is lowered whereby the formation of NOX is inhibited. Combustion in the secondary combustion ~2~5~3 zone is delayed because the secondary combustion zone is shielded by the pri~ary zone from direct contact with incoming air. This delay in the mixing of the fuel and air allows for dilution of the air with corQbustion products from the primary combustion zons, resulting in a lower co~bustion temperature which inhihits the for~ation of NOX in the secondary combustion zone.
While the present invention has been described as it relates to a natural draEt burner apparatus, it is to be understood that the inven-tion is applicable to a wide variety of burner designs, including those utilizing forced draft. In additionr more than one fuel discharge nozzle of the presen-t invention can be utilized in a single burner apparatus, as for example, the burner apparatus disclosed in 15 U.S~ Patent No. 3,033,273 issued on r~ay 8, 1362. Further, the fuel discharge nozzls and shielding cone utilized in burners in accordance with this invention can take various forms and shapes so long as the functional li~itations described above are ~et thereby.
In order to facilitate a clear understanding of th~
method and apparatus of the present invention, the following example is ~iven.
Example A burner apparatus 10 designed for a heat release oE
6,000,000 BTU/hr by burning natural gas having a calorific value of 930 BTU/SC~ is firsd into a furnace char~ber. The nozzle 38 includes a first set of 6 orifices 56 of 0.0625 inch diameter, a second set of 4 orifices 58 of 0.1405 inch 30 dia~eter and a third set of 4 orifices 60 of 0.1875 inch ~s~
dia~eter. The axes of the oriEices 56 are at an angle of 90 with the axis of the nozzle 38, the axes of the orifices 58 are at an angle of 4~ with the axis of the nozzle 38 and the axes of the oriEices 60 are at an angle of 10 therewith.
The fuel is supplied -to the nozzle 3~ at a pressure oE
about 15 psiq. and at a rate of about 6452 SCF/hr. The first portion o fuel discharged through the ignition nozzles 56 is at a rate of about 596 ~CF/hr., the second portion of fuel discharged through the primary co~bus-tion orifices 5~ is at a rate of about 1986 SCF/hr. and the remaining portion of fuel discharged through the secondary coinbustion oriEices 60 is at a rate oE about 3870 SC~/hr.
The discharged Euel is co~bined witn air in the burner apparatus 10 and burned whereby a heat release in the furnace chamber of about 6,000,~00 ~TU/hr. is realized. ~he stack emissions from the simulated furnace chamber contain an NOX concentration of less than about 40 pprn. A
conventional burner including a conven-tional nozzle fired in the furnace chamber in the same manner and under the same conditions creates stack emissions containing an NOX concentration of more thar- about 70 ppm.
Thus, the present invention is well adapted to carry out the objects and attain the advantages mentioned as well as those inherent therein. While ~resently preferred embodiments of the invention have been described herein for purposes oE this disclosure, numerous changes in the construction of parts and in the arrangenent of parts and steps will suggest themselves to those skilled in the art, ~2~S~
which changes are encompassed wi-thin the spiri-t of this invention as defined by the appended claims.
~hat is claimed i5:
n
Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method of combusting a fuel-air mixture where-in fuel is discharged from one or more nozzles disposed within a burner housing, air introduced into said housing is mixed with the fuel and the resulting fuel-air mixture is ignited and combusted, the improvement whereby the formation of nitrogen oxides is inhibited comprising the steps of:
discharging a first portion of said fuel from each of said one or more nozzles through one or more orifices therein whereby said fuel mixes with air and provides an ignition zone adja-cent said nozzle;
discharging a second portion of said fuel from each of said one or more nozzles through one or more additional orifices therein whereby said second portion of fuel is distributed in a turbulent pattern which causes said fuel to mix with a rate of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone; and discharging the remaining portion of said fuel from each of said one or more nozzles through one or more additional orifices therein whereby said remaining portion of fuel is distributed within and downstream of said primary com-bustion zone, is mixed with air from said pri-mary combustion zone which is diluted with combustion products and is burned in a secon-dary combustion zone substantially shielded from direct contact with incoming air by said primary combustion zone.
discharging a first portion of said fuel from each of said one or more nozzles through one or more orifices therein whereby said fuel mixes with air and provides an ignition zone adja-cent said nozzle;
discharging a second portion of said fuel from each of said one or more nozzles through one or more additional orifices therein whereby said second portion of fuel is distributed in a turbulent pattern which causes said fuel to mix with a rate of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone; and discharging the remaining portion of said fuel from each of said one or more nozzles through one or more additional orifices therein whereby said remaining portion of fuel is distributed within and downstream of said primary com-bustion zone, is mixed with air from said pri-mary combustion zone which is diluted with combustion products and is burned in a secon-dary combustion zone substantially shielded from direct contact with incoming air by said primary combustion zone.
2. The method of claim 1 wherein said first portion of fuel is a rate in the range of from about 1% to about 25% of the total rate of fuel discharged from each of said one or more nozzles.
3. The method of claim 2 wherein said second portion of fuel is a rate in the range of from about 1% to about 60%
of the total rate of fuel discharged from each of said one or more nozzles.
of the total rate of fuel discharged from each of said one or more nozzles.
4. The method of claim 1 wherein the total rate of air introduced into said housing is substantially equal to or greater than the rate required for the stoichiometric burning of the total rate of fuel discharged from said one or more nozzles.
5. In a method of burning fuel in a furnace chamber where air is introduced into the chamber by way of an opening therein and fuel is introduced into the chamber by way of a fuel discharge nozzle positioned within the air opening, the improvement whereby the formation of nitrogen oxides is inhibited comprising the steps of:
introducing a first portion of said fuel into said furnace chamber through a first set of orifi-ces in said nozzle whereby said fuel mixes with air and provides an ignition zone therein;
introducing a second portion of said fuel into said furnace chamber through a second set of orifi-ces in said nozzle whereby said fuel is distributed therein in a turbulent pattern which causes said fuel to mix with a rate of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone adjacent said igni-tion zone; and introducing the remaining portion of said fuel into said furnace chamber through a third set of orifices in said nozzle whereby said fuel is distributed within and downstream of said pri-mary combustion zone, is mixed with air from said primary combustion zone which is diluted with combustion products and is burned in a secondary combustion zone therein substan-tially shielded from direct contact with incoming air by said primary combustion zone.
introducing a first portion of said fuel into said furnace chamber through a first set of orifi-ces in said nozzle whereby said fuel mixes with air and provides an ignition zone therein;
introducing a second portion of said fuel into said furnace chamber through a second set of orifi-ces in said nozzle whereby said fuel is distributed therein in a turbulent pattern which causes said fuel to mix with a rate of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone adjacent said igni-tion zone; and introducing the remaining portion of said fuel into said furnace chamber through a third set of orifices in said nozzle whereby said fuel is distributed within and downstream of said pri-mary combustion zone, is mixed with air from said primary combustion zone which is diluted with combustion products and is burned in a secondary combustion zone therein substan-tially shielded from direct contact with incoming air by said primary combustion zone.
6. The method of claim 5 wherein said second portion of fuel is distributed by said second set of orifices in an outwardly flaring pattern whereby said primary combustion zone is of an outwardly flaring shape.
7. The method of claim 5 wherein said first portion of fuel is a rate in the range of from about 1% to about 25%
and said second portion of fuel is a rate in the range of from about 1% to about 60% of the total rate of fuel discharged from said nozzle.
and said second portion of fuel is a rate in the range of from about 1% to about 60% of the total rate of fuel discharged from said nozzle.
8. The method of claim 5 wherein the total rate of air introduced into said furnace chamber is substantially equal to or greater than the rate required for the stoichiometric burning of the total rate of fuel discharged from said nozzle.
9. In a burner apparatus for combusting a fuel-air mixture wherein fuel is discharged from one or more nozzles disposed within a chamber, air is caused to flow into the chamber whereby it mixes with the fuel and the resulting fuel-air mixture is ignited and combusted, the improvement whereby the formation of nitrogen oxides is inhibited comprising:
each of said one or more nozzles having one or more ignition orifices disposed therein positioned to discharge a first portion of said fuel therethrough whereby said fuel mixes with air and provides an ignition zone adjacent said nozzle;
one or more primary combustion orifices disposed in each of said one or more nozzles positioned to discharge a second portion of said fuel therethrough whereby said fuel is distributed in a turbulent pattern which causes said fuel to mix with a rate of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone; and one or more secondary combustion orifices disposed in each of said nozzles interiorly of said primary combustion orifices positioned to discharge the remaining portion of said fuel therethrough whereby said fuel is distributed within and downstream of said primary com-bustion zone, is mixed with air from said pri-mary combustion zone diluted with combustion products and is burned in a secondary com-bustion zone substantially shielded from direct contact with incoming air by said pri-mary combustion zone.
each of said one or more nozzles having one or more ignition orifices disposed therein positioned to discharge a first portion of said fuel therethrough whereby said fuel mixes with air and provides an ignition zone adjacent said nozzle;
one or more primary combustion orifices disposed in each of said one or more nozzles positioned to discharge a second portion of said fuel therethrough whereby said fuel is distributed in a turbulent pattern which causes said fuel to mix with a rate of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone; and one or more secondary combustion orifices disposed in each of said nozzles interiorly of said primary combustion orifices positioned to discharge the remaining portion of said fuel therethrough whereby said fuel is distributed within and downstream of said primary com-bustion zone, is mixed with air from said pri-mary combustion zone diluted with combustion products and is burned in a secondary com-bustion zone substantially shielded from direct contact with incoming air by said pri-mary combustion zone.
10. The burner apparatus of claim 9 which is further characterized to include means attached thereto for creating a protected space adjacent each of said one or more nozzles and said one or more ignition orifices therein.
11. The burner apparatus of claim 9 wherein said one or more ignition orifices are of a size whereby said first por-tion of said fuel is a rate in the range of from about 1% to about 25% of the total rate of fuel discharged from said nozzle.
12. The burner apparatus of claim 11 wherein said one or more primary combustion orifices are of a size whereby said second portion of fuel is an amount in the range of from about 1% to about 60% of the total rate of fuel discharged from said nozzle.
13. In a burner apparatus for combusting a fuel-air mixture wherein fuel is discharged from a nozzle disposed within a housing, air is caused to flow into the housing whereby it mixes with the fuel and the resulting fuel-air mixture is ignited and combusted, the improvement whereby the formation of nitrogen oxides is inhibited comprising:
said nozzle having one or more ignition orifices disposed therein positioned transversely to the direction of flow of said air and being of a size and number such that a first portion of said fuel is discharged therethrough which mixes with air and provides an ignition zone adjacent said nozzle;
one or more primary combustion orifices disposed in said nozzle positioned transversely to the direction of flow of said air and being of a size and number such that a second portion of said fuel is discharged therethrough and distributed in a turbulent pattern which causes said fuel to mix with an amount of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone; and one or more secondary combustion orifices disposed in said nozzle interiorly of said primary com-bustion orifices of a size and number such that the remaining portion of said fuel is discharged therethrough and is distributed within and downstream of said primary com-bustion zone, is mixed with air from said pri-mary combustion zone which is diluted with combustion products and is burned in a secon-dary combustion zone substantially isolated from direct contact by incoming air by said primary combustion zone.
said nozzle having one or more ignition orifices disposed therein positioned transversely to the direction of flow of said air and being of a size and number such that a first portion of said fuel is discharged therethrough which mixes with air and provides an ignition zone adjacent said nozzle;
one or more primary combustion orifices disposed in said nozzle positioned transversely to the direction of flow of said air and being of a size and number such that a second portion of said fuel is discharged therethrough and distributed in a turbulent pattern which causes said fuel to mix with an amount of air in excess of that required for the stoichiometric burning thereof and to burn in a primary combustion zone; and one or more secondary combustion orifices disposed in said nozzle interiorly of said primary com-bustion orifices of a size and number such that the remaining portion of said fuel is discharged therethrough and is distributed within and downstream of said primary com-bustion zone, is mixed with air from said pri-mary combustion zone which is diluted with combustion products and is burned in a secon-dary combustion zone substantially isolated from direct contact by incoming air by said primary combustion zone.
14. The burner apparatus of claim 13 which is further characterized to include an air shielding means for creating a protected space downstream thereof disposed adjacent said nozzle and said one or more ignition orifices therein.
15. The burner apparatus of claim 13 wherein said first portion of said fuel is a rate in the range of from about 1%
to about 25% of the total rate of fuel discharged from said nozzle.
to about 25% of the total rate of fuel discharged from said nozzle.
16. The burner apparatus of claim 13 wherein said second portion of fuel is a rate in the range of from about 1% to about 60% of the total rate of fuel discharged from said nozzle.
17. The burner apparatus of claim 13 wherein the axes of said one or more ignition orifices are substantially per-pendicular to the direction of flow of said air into said housing, the axes of said one or more primary combustion orifices are inclined in the direction of flow of said air at an angle in the range of from about 15° to about 70°
therewith and the axes of said one or more secondary com-bustion orifices are parallel to or inclined in the direc-tion of flow of said air into said housing at an angle in the range of from about 1° to about 30° therewith.
therewith and the axes of said one or more secondary com-bustion orifices are parallel to or inclined in the direc-tion of flow of said air into said housing at an angle in the range of from about 1° to about 30° therewith.
18. In a burner apparatus for combusting a fuel-air mixture wherein fuel is discharged from a nozzle disposed centrally within a cylindrical housing, air is caused to flow into the housing whereby it mixes with the fuel and the resulting fuel-air mixture is ignited and combusted, the improvement whereby the formation of nitrogen oxides is inhibited comprising:
said nozzle having a first set of orifices disposed therein positioned to discharge fuel therearound in a plane substantially perpen-dicular to the axis of said nozzle and being of a size and number such that a first portion of said fuel is discharged therethrough which mixes with air and provides an ignition zone adjacent said nozzle;
air shielding means for creating a protected space adjacent said first set of orifices attached within said housing;
a second set of orifices disposed in said nozzle positioned to discharge fuel therearound in an outwardly flaring pattern and being of a size and number such that a second portion of said fuel is discharged therethrough with tur-bulence which causes said fuel to mix with an amount of air in excess of that required for the stoichiometric burning thereof and to burn in an outwardly flaring primary combustion zone; and a third set of orifices disposed in said nozzle positioned interiorly of said second set of orifices and being of a size and number such that the remaining portion of said fuel is discharged therethrough and distributed within and downstream of said outwardly flaring pri-mary combustion zone, is mixed with air from said primary combustion zone which is diluted with combustion products and is burned in a secondary combustion zone substantially shielded from direct contact with incoming air by said primary combustion zone.
said nozzle having a first set of orifices disposed therein positioned to discharge fuel therearound in a plane substantially perpen-dicular to the axis of said nozzle and being of a size and number such that a first portion of said fuel is discharged therethrough which mixes with air and provides an ignition zone adjacent said nozzle;
air shielding means for creating a protected space adjacent said first set of orifices attached within said housing;
a second set of orifices disposed in said nozzle positioned to discharge fuel therearound in an outwardly flaring pattern and being of a size and number such that a second portion of said fuel is discharged therethrough with tur-bulence which causes said fuel to mix with an amount of air in excess of that required for the stoichiometric burning thereof and to burn in an outwardly flaring primary combustion zone; and a third set of orifices disposed in said nozzle positioned interiorly of said second set of orifices and being of a size and number such that the remaining portion of said fuel is discharged therethrough and distributed within and downstream of said outwardly flaring pri-mary combustion zone, is mixed with air from said primary combustion zone which is diluted with combustion products and is burned in a secondary combustion zone substantially shielded from direct contact with incoming air by said primary combustion zone.
19. The burner apparatus of claim 18 wherein said first portion of fuel is a rate in the range of from about 1% to about 25% of the total rate of fuel discharged from said nozzle and said second portion of fuel is a rate in the range of from about 1% to about 60% of the total rate of fuel discharged from said nozzle.
20. The burner apparatus of claim 18 wherein the por-tion of said nozzle containing said orifices is hemispheri-cal in shape and said first set of orifices lies in a plane substantially perpendicular to the axis of said nozzle, the orifices of said second set are inclined at an angle in the range of from about 15° to about 70° with the axis of said nozzle and the orifices of said third set are parallel to or are inclined at an angle of from about 1° to about 30° with the axis of said nozzle.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US73107885A | 1985-05-06 | 1985-05-06 | |
| US731,078 | 1985-05-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1245543A true CA1245543A (en) | 1988-11-29 |
Family
ID=24937974
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000486490A Expired CA1245543A (en) | 1985-05-06 | 1985-07-09 | Low no.sub.x formation fuel burning methods and apparatus |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0210313A1 (en) |
| JP (1) | JPS61256106A (en) |
| CA (1) | CA1245543A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7213348B2 (en) | 2004-11-12 | 2007-05-08 | Bsh Home Appliances Corporation | Gas burner and air heater assembly for a gas clothes dryer |
| CN111336517A (en) * | 2018-12-18 | 2020-06-26 | 无锡小天鹅电器有限公司 | Nozzle assembly of burner, burner and clothes dryer |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3033273A (en) * | 1959-11-09 | 1962-05-08 | Zink Co John | Fuel burner assembly |
| US4004875A (en) * | 1975-01-23 | 1977-01-25 | John Zink Company | Low nox burner |
| US4157890A (en) * | 1977-09-26 | 1979-06-12 | John Zink Company | NOx abatement in gas burning where air is premixed with gaseous fuels prior to burning |
| US4162140A (en) * | 1977-09-26 | 1979-07-24 | John Zink Company | NOx abatement in burning of gaseous or liquid fuels |
| US4395223A (en) * | 1978-06-09 | 1983-07-26 | Hitachi Shipbuilding & Engineering Co., Ltd. | Multi-stage combustion method for inhibiting formation of nitrogen oxides |
| DE2908427C2 (en) * | 1979-03-05 | 1983-04-14 | L. & C. Steinmüller GmbH, 5270 Gummersbach | Method for reducing NO ↓ X ↓ emissions from the combustion of nitrogenous fuels |
| JPS59157407A (en) * | 1983-02-25 | 1984-09-06 | Hitachi Zosen Corp | Composite double-stage low nox burner with gas mixing combustion |
-
1985
- 1985-07-09 CA CA000486490A patent/CA1245543A/en not_active Expired
- 1985-10-03 EP EP85307097A patent/EP0210313A1/en not_active Withdrawn
- 1985-10-18 JP JP23311685A patent/JPS61256106A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0210313A1 (en) | 1987-02-04 |
| JPS61256106A (en) | 1986-11-13 |
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