CA2175934C - Fuel burner apparatus and method employing divergent flow nozzle - Google Patents

Abstract

A burner for burning fuel in an oxidant having a fuel nozzle sandwiched between upper and lower oxidant nozzles. The fuel nozzle and upper and lower oxidant nozzles produce fuel and oxidant jets of outwardly divergent, fan-shaped configuration to provide a wide uniform flame and thus the elimination of hot spots. Upper and lower secondary oxidant nozzles can be provided in staged combustion such that fuel is burned and oxidant supplied by the upper and lower oxidant nozzle means in the substoichiometric ratio and then combustion is completed by oxidant supplied by the secondary upper and lower oxidant nozzles. In another aspect, a nozzle is provided in which a passageway is divided in a lengthwise direction and thus the flow of oxidant flowing through the passageway is divided into a plurality of subflows of equal velocity and of gradually divergent configuration to prevent the decay of a fan-shaped flow of oxidant from the nozzle.

Description

Docket No. 93A224 FUE~ BURNE R APPARAlUS ANlD I~OD
EMPLO~NG DIVERGENT FL~W NOIZZIE
TRouNn OF TITF INVI~ON
The present invention relates to a fuel burner apparatus and method for burning a fuel in an oxidant. More particularly, the present invention relates to sucll a fuel burner apparatus and method in which the oxidant is oxygen or oxygen erlriched air. The present invention also relates to a nozzle that is capable of producing a flat, &vergent uniform S flow of a fluid that is particularly suited for forming oxidant nozzles used ill a fuel burner apparatus and method in accordance with the present invention.
Fuel burners are used in many industrial ~ ",~ in which a material to be processed is melted, for example, glass, copper, alurninum, iron, and steel. In order to 10 maximize the he~t available from the fuel, oxy-fuel burners have evolved m which the fuel is burned in oxygen or oxygen enriched air. These bumers generally produce flames having a highly .~ r,l~ power output which carl in turn p}oduce hot spots in themelt. Typically, such bumers utilize high velocity oxidant and high mass flow rates of fuel to produce the high power outputs. Taken together, the l / ~"r, ,~ r 1 heating tends 15 to evolve volatiles within the melt and the high velocities tend to ffntrain feed matffial to the exhaust of the fumace. The ffntrained feed material and evolved volatiles can thffeby be lost and pollute the ~I~u~ Qc or can form a deposit which ~, "" " ~ within the furnace or exhaust heat recovffy systems used m I ; with furnaces.
A still furthff problffm in oxy-fuel bumQs is that the high ~C114J~l~UlC ~III~ iUII
of the fuel in oxygQn or oxygen fflriched air can produce polluting NOX.

Docket No. 93A224 As will be discussed, the present invention provides a burner apparatus and method that is less susceptible than prior art apparatus and m~thn~lnlngy to forming hot spots and entraining feed particles within the flow of oxidant and fuel and furdler, is readily adaptable to employ a NOX limiting form of .'1 " "1."~ .. ", s S~lMMARY OF TTlF. INV~ON
Ihe present invention provides a fuel bumff for burning fuel in an oxidant fuel noz~le means and upper and lower noz~le means. The fuel noz~le means 10 p}oduces a fuel jet of outwardly divergent, fan-shaped .-nnfi~tinn whicll is adapted to burn within the oxidant with an outwardly extending and divergent flame. The upper and lower oxidant noz~le means are separate and distinct from one another and from the fuel nozle means for producing upper and lower oxidant jets of outwardly divergent, fan-shaped cnnfi~tinn located above and below the fuel jet, respectivel~ . The oxidant lS jets have a lower velocity than the fuel jets such that the oxidant is aspirated into the fuel.
In another aspect of the present invention, the present invention provides a method of burning fuel in an oxidant. In accordance with such method a fuel jet is produced of outwardly divergent, fan-shaped ~nnfi~ tinn so that the fuel jet will burn within the 20 oxidant with an outv-~ardly extending and divergent flame. Upper and lower oxidant jets, separate and distinct from one another and from the fuel jet are produced at locations above and below the fuel jet, ~ iv~ly, and so as to have a lower velocity than the fuel jet and thereby aspirate oxidant into the fuel.
In these forgorng aspects of the present invention, the fuel jet and ~xidant no~le are outwardly divergent and fan-shaped to produce an outwardly extending flame burning over a wide ar~ The wide area of ~ . has the advantage of permitting high levels of heat input into a melt while ~ hot spots within the melt. The upper and lower oxidant noz~:le means produce low velocity and therefore high pressure oxidant jels which ~ tt ln Ptl~ctD~ a p~ ~t~hat t asptlalc tt e ~ to tt c t ~I

D~930225 2 1 7 5 9 3 4 PATENT
Docket No. 93A224 Since, however, the oxidant jets are of low velocity, they tend not to entrain feed particles and thus serve to shield the fuel jet.
In still another aspect, the present invention provides a nozle for p~oducing a flat, 5 uniformly divergent flow of a fluid. Ihis nozzle is IJ~Li~uLuly well suited for selving as the upper and lower oxidant noz~;le means. Ihe nozzle cornprises a body portion including a ~ a~way~ Ihe ~ ,w~ has an outlet for d;~ g a duid flow and an inlet to the ~ cway for introducing the fluid flow into the pa~a~way. A meansis provided for dividing the ~ a~v-a~ in a lengLhwise direction thereof and thus, the 10 flow of the fluid into a plurality of subflows having velocities of esserltially equal magnitude and oriented so æ to gradually diverge in a transverse directiorl of the flow of the fluid.
As stated ahove, the present invention can be adapted to reduce NOX forrnation.
15 In prior art oxy-fuel burners, Al",..~l,l,r.;,- nitrogen can react with oxygen to produce thermal NOX. In addition, fuel radicals such as CIH can react with Al . "n~ , ;c nitrogen to form prompt NOX. In this æpect of the present invention, r~lmh -ction of the fuel occurs in two stages in order to reduce both thermal and prompt NOX formation. In a frrst of the two stages of .~ ""~1"~1; ." of the fuel within the oxidant supplied by 20 the upper and lower oxidant jets is ~ ""~ Ihe blrrner further comprises secondary upper and lower oxidant noz~le means separate and distinct from one another and the upper and lower oxidant noz~le and fuel jet means. Ihe upper and lower oxidant no~le and fuel jet means produce at leæt one pair of upper and lower secondary oxidant jets of outwardly divergent, fan-shaped confi~-~tinn located above and b,low the upper 25 and lower oxidant jets, ~ iv~ly, for supplying sufficient amounts of oxidant to complete ~nmhllctinn of t'ne fuel. Ihe ~nmhllctinn of the fuel is thereby r~ompleted in a second of two stages of ~."~ It is to be noted that the sufficient amounts of oxidant can either be just that required to romplete ~ or 't~ldliv~ly, can be in ~ lu~ rl~ ;~ amounts. lhe ~ l" ~l~llo~y involved in this æpect of the present 30 invention comprises producirlg at leæt one pair of upper and lower secondary oxidant jets of outwardly divergent, fan-shaped ~ ~" ,~ "~ at locations above and below the upper ~ =~
DMR930225 2 1 7 5 9 3 4 PA~ENT
Docket No. 93Aæ4 and lower oxidant jets"~liv~ly, so as to supply sufficient amounts of oxidant tocomplete .~""1",~1;.", of the fuel. Ihis staging of c~ mh lctirln has been found to lower NOX formation.
S RRIFF DFA~(~RTT~ON OF TElF DF~AWIN('~
While the ~ ;r~ ,.,., collcludes with claims distinctly pointing out the subjectmatter that Applicant regards as his invention, it is believed tbat the invention will be better understood when taken in connection with the awJ~ Jallyillg dra~ings in which:
Fig. I is a top plan view of a bumer in accordance with the present invention;
Fig. 2 is an elevational view of Fig. I, Fig. 3 is a front elevational view of Fig. I;
Fig. 4A is a La~ll~,llL~y or a sectional view taken along line 4-4 of Fig. 3, Fig. 4B is a La~ll~ll~y front elevational view of Fig. 4A;
Fig. 4C is a La~~ ~y~ cross-sectional view taken along line 4C of Fig. 4A;
Fig. 4D is a La~ll~ ~y~ cross-sectional view taken along line 4D of Fig. 4A;
Fig S is a L~ y side elevational view of another ernho;' of a burner in accordance with the present invention employing oxidant staging and illustrated as being set m a bumer block shown in section;
Fig. 6 is a front elevational view of Fig. 5.
Fig 7 is a top planar view of a nozzle employed in the bumer of Fig. 5.

. ~ ' 21 75934 D~930225 PAT~NT
Docket No. 93A224 Fig. 8 is an elevational view of a flame issuing forth from the burner of Fig. 5.
with the bumer block being drawn in section, ~,nd Fig 9 is a top plancir view of Fig. 8.
DETA~T Fn DE!~CRITYriON
Wlth reference to Figs. 1, 2 and 3 a burner 10 in acoc,rd~,nce w~th the present invention is illusttated. Burner 10 includes a fuel no~le 12, which, as will be described, 10 is designed to produce a fuel jet of outwc,rdly divergent, fcn-sha~ed c~-nfi~-riti in Such a fuel jet will burn witbin suitably shal~ed oxidcnt jets with an outwc,rdly extending and &vergent flame. Upper cnd lower oxidant nozzles 14 c,nd 16 are prcivided for producing upper c,nd lower oxidc,nt jets of outwardly divergent, fc,n-shaped ~infi~iritinn located above c,nd below the fuel jet. Ihe upper and IOWff oxidant jets of upper and lower 15 oxid-c,nt noz~les 14 and 16 have a lower velocity than the fuel jet. As a result, the oxidant has a higher pressure than the fuel and the oxid~nt tends to æpirate into tlle fuel. Thus, in the present invention, a high velocity fuel jet is shielded by low velocity oxidant jets to help prevent the c~ llr~ll of feed that wou',d otherwise occur with burners of the prior a~t. Burner 10 is specifically designed to burn natural gas in an oxidant of 20 essentially pure oxygen. It is understood that more generally the teachings set forth herein have ~ y to different fuel gases such as hydrogen, ethane, propane, butane acetylene and liquid fuels such as diesel fuel, heating oils, etc. Additionally the oxidant can be oxygen enriched air.
As can be ~ ~L the fuel bums along the length of the flame and oxidc,nt jets. As such, unburned fuel is heated and becomes ~JIV~ l v~ more buoyant along the leng~th of the flame, ca~-,sing the flame to lick upwardly, away from the heat load. In order to prevent this, lower oxidant noz~,e mear,s 16 can be designed such that the lower oxidant jet has a higher mass flow rate t~,an that of the upper oxidant jet issuing from upper oxidant noz~:le 14. I~is will result in the ~ ~ ", ~ ", of the fuel being primarily in oxid~,nt supplied by the lower oxidant jet of higher mass flow rate with the "l~ lc~ ;ly s ` 2 1 7593~
DMR930225 PA~T
Docket No. 93A224 more buoyant unburned fuel burning in the oxidant supplied by the upper oxidant jet. As can be a~lulcc;~ an ~ IH~ of the present invention could be ~~ uc,~d witn upper and lower oxidant noz~les producing oxidant jets of equal mass flow rates.
S Burner 10 is provided with a body 18 of elongated configuration l~aving top and bottom walls 20 and 22 and side walls 24 and 26. Angled l~illru~ wl~ rnembers 28-34 are provided to stiffen body portion 18. Central fuel nozle 12 divides body portion 18 into upper and lower oxidant no~zles 14 and 16 which include upper and lower pa~ d~wa,v~ 36 and 38 having outlets 40 and 42 and inlets 44 and 46.
A coupling assernbly 48 is cormected to the rear of body portion 18 to introduceoxidant into body portion 18 which in turn flows into inlets 44 and 46 of upper and lower oxidant nozzles 14 and 16 and t'nereaPler, flows of outlets 40 and 42 thereof.
Fuel no~le 12 is supported within body 18 by upper and lower sets of vanes 50 and 52. Vanes 50 and 52 are connected to top and bottom walls 20 and 22 and to fuel nozzle 12. Vanes 50 and 52 divide pa~ia~wa,ys 36 and 38 in the lengthwise direction and therefore the flow of oxidant passing through upper and lower ~a~ay~Wdys 36 and 38 into a plurality of subflows. Vanes 50 and 52 are specifically designed such that the velowties of the subflows will have an essentially equal magnitude and be oriented so as to gradually diverge in a transverse direction to the flow of the oxidant. rnis is effectuated by outwardly curving vanes 50 and 52 which are designed such that tangents drawn at t'neir maximum cu~vatures all intersect at one location within the respective of the ~ rway~ 40 and 42 of which vanes 50 and 52 subdivide. Although hidden, the vanes extend rearwardly to the inlets 44 and 46 of upper and lower oxidant no~zles 14 and 16. A further advantage of the vaned upper and lower oxidant no7~les is ~at the vanes allow for effective self cooling of burner 10 without extemal water cooling.
As stated previously, upper and lower oxidant nozles 14 and 16 are designed suchthat the lower oxidant jet will have a higher rnass flow rate than the upper ~xidant nozle jet. Tnis is eflfected by a~ uu~ ly sizing the l~~ uldl, transverse woss-section of . `~ 2 ~ 7593~ `
D~930225 PATENT
Docket No. 93A~24 upper and lower oxidant nozz;les to be in a ratio of cross-sectional areas srnaller than unity. Ihe ratios are preferably in a range of between about 0.125 and about 0.5.
It is to be noted here that the design of oxidant nozzles 14 and 16 could be used 5 in other ~rrlj~tionc For instance, an oxidant nozzle could be designed in the rnanner provided herein for use in creating a fiat, fan-shaped outwardly divergent field of oxidant below a fuel jet or burner or in other words, for oxygen-lancing purposes~
~Ith reference to Figs. 4A through 4D, fuel nozzle 12 is preferably formed in two 10 sections 56 and 58. Fuel nozzle 12 is in the form therefore of a central body portion having a chamber 60 and a plurality of ~ad~ y~ 62 of equal length, spa~ed apart from one another, and gradually fanning out from chamber 60. Chamber 60 ~
between passages 62 and a fuel inlet 64 such that fuel flows from fuel inlet 64 and out of passages 62. Passages 62 gr~dually fan out from cha~nber 60 so that the resultant fuel 15 jet v~ill fan out. Ihe equal length of passages 62 produce an equal pressure drop and therefore equal velocity so that the fuel jet will fan out or horizontally diverge with liKle decay. In the illustrated L.. 1 ~ 1.. Il the ratio of the average velocities of the fuel versus oxidantis~ t~ly 13.5to IØ Aconduit66of,~~ ulal-transversecross-sectiorl connects to a coupling 68 by means of a transition piece 70 ~vhich transitions from a 20 circular, transverse cross-section to a rectangular, transverse cross-section. If fuel nozzle 12 were to be employed to burn liquid fuels, suitable fuel nozzles (known ~vell in the art) would have to be attached to passages 62.
~Ith reference now to Figs. 5, 6 and 7 an alternative L.l~;hl~ l of a fuel burner 25 appara~us of the present invention is illustrated. The illustrated L~ '- ' stages oxidant into the fuel to reduce polluting NOX emissions while producing a flame paKern illustrated in Figs. 8 and 9 which is horizontally divergent, fan-shaped and resistant to decay along the length of the f~ame pattenL This is effected with the use of burner 10 such that fuel and oxidant is supplied from oxidant nozzles 14 and 16 in ~"l, ~l~ .;. l .: .. . ,~l . .c 30 amounts or in other words the oxidant supplied does not completely support c.... ,1...~l ;. ,, ~
of the fuel. Ihereafter, .~ ;-... of fuel is completed in upper and lower secondary . ` 21 75934 D~930æS PAT~T
Docket No. 93A224 oxidant jets of outwardly divffgffnt, fan-shaped rA)nfigll~tir,n supplied at L~cations above and below the Uppff and IOWff oxidant jets, ~ , by upper and IOWff secondary oxidant no~les 72 and 74 set within a burnff block 75 along with burnff 10. Ihe incomplete combustion occurs in a first stage of the ~l mhll~ti~n and the completed S c~ occurs in a second stage of the ~mhl~tir~n located du~v~ wll from the first stage of the rl~" ll ."~ ;. " 1. As discussed above the two stage rl ~" ,1."~1;. ." ,`""t. ~ ~IJI ~t~l by the presffnt invffntion tffnds to reduce NOX ffnissions. Additionally, NOX emissions are also lowered by the spacing of passages 62 of fuel nozzle 12. Ihe sl~aces bet~veen passages 62 pffmit IV~ilUlJIaliUll zones to aspirate rrlmhll~hr,n gases into the fuel and 10 thereby reduce NOX emissions.
Uppff and lower secondary oxidant no:z~les 72 and 74 have opposed side walls 76 and 78 (for Uppff secondary oxidant nozle 72) and 80 and 82 (for 10Wff secondaryoxidant nozzle 74) connected to sets of top and bottom walls 84, 85, $6 and 87 are 15 provided which are connected to side walls 76 and 78 and 80 and 82 of upper and lowff secondary oxidant nozzles 72 and 74, l~liv~l~y. Ihe no~;les are also provided with back walls 88 and 90. Nozles 72 and 74 are also provided with rectangular discharge outlets 92 and 94 and vanes 96 and 98 having the same c~ nfigll~tirn as vanes 34 and 36 of Uppff and IOWff nozzles 14 and 16. Although discharge outlets 92 and 94 are designed 20 to inject oxidant in the same ratio as upper and IOWff nozles 14 and 16, an c;ll~
of the present invffntion is possible in which discharge outlets 92 and 94 llave the same cross-sectional area and thffefore possibly not in the same ratio of upper and lower nozzles 14 and 16. In the illustrated ~ no~le 72 is provided wi h a front wall 97 within which discharge outlet 92 is defned.
Noz~:les 72 and 74 and burnff 10 are set within pæsages 100, 102, and 104 provided in burner block 75. It should be noted that passage 102 recesses burner 10 from nozles 72 and 74 to allow for the dvwl~ilwll injection of oxidant by nozzles 72 and 74 and thffefore the second stage of ~." ,l ,~ , Fu~ llllul~, the surfaces 106,108,1 10, 30 andll2Ofburnffblock75,1OcatedinfrontofburnfflOandformingthefrontofpæsage 102, are designed to allow the flame produced by burnff 10 to g~adually divffge.

-Docket No. 93A224 Conventional quick-disconnect fittings 114 and 116 are connected to upper and lower secondary oxidant noz~;les 72 and 74, ~ iv~ly~ for illllUdU~,i Ig the secondary oxidant into the upper and lower secondary oxidant noz~les 72 and 74, I~Li~ y.
S While the invention has been described with reference to preferred ~Illln)dilll~llt, it would be understood that numerous additions and omissions can be rnade without departing from the spirit and scope of the invention.

Claims (2)

1. A nozzle for producing a flat, uniformly divergent flow of a fluid, said nozzle comprising:
a body portion including a passageway having an outlet for discharging the flow of the fluid and an inlet to the passageway for introducing the flow of the fluid into the passageway; and a plurality of outwardly curving vanes extending from the inlet to the outlet, transversely dividing the passageway and therefore the flow of the fluid into a plurality of subflows having an essentially equal magnitude and oriented so as to gradually diverge in a transverse direction to the flow of the fluid.

2. The nozzle of claim 1, wherein the passageway has a rectangular transverse cross-section.