CA1197143A - Dual register, split stream burner assembly - Google Patents
Dual register, split stream burner assemblyInfo
- Publication number
- CA1197143A CA1197143A CA000378443A CA378443A CA1197143A CA 1197143 A CA1197143 A CA 1197143A CA 000378443 A CA000378443 A CA 000378443A CA 378443 A CA378443 A CA 378443A CA 1197143 A CA1197143 A CA 1197143A
- Authority
- CA
- Canada
- Prior art keywords
- fuel
- tubular member
- burner assembly
- air
- enclosure
- 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.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D1/00—Burners for combustion of pulverulent fuel
- F23D1/02—Vortex burners, e.g. for cyclone-type combustion apparatus
Abstract
DUAL REGISTER, SPLIT STREAM
BURNER ASSEMBLY
ABSTRACT OF THE DISCLOSURE
A burner assembly in which an inlet is located at one end of an annular passage for receiving fuel, and an outlet is located at the other end of the passage for discharging the fuel. A plurality of members are disposed within the annular passage for splitting up the fuel discharging from said outlet so that, upon ignition of said fuel, a plurality of flame patterns are formed. A register assembly is provided which includes an enclosure for receiving air and a divider for directing the air from the enclosure towards the outlet in two parallel paths extending around the burner. Registers are disposed in each of the paths for regulating the quantity of air flowing through the paths. According to an alternative embodiment, a divider cone is disposed within the annular passage for dividing the stream of fuel passing through the passage into two parallel coaxial streams and additional secondary air is introduced into the outer stream.
BURNER ASSEMBLY
ABSTRACT OF THE DISCLOSURE
A burner assembly in which an inlet is located at one end of an annular passage for receiving fuel, and an outlet is located at the other end of the passage for discharging the fuel. A plurality of members are disposed within the annular passage for splitting up the fuel discharging from said outlet so that, upon ignition of said fuel, a plurality of flame patterns are formed. A register assembly is provided which includes an enclosure for receiving air and a divider for directing the air from the enclosure towards the outlet in two parallel paths extending around the burner. Registers are disposed in each of the paths for regulating the quantity of air flowing through the paths. According to an alternative embodiment, a divider cone is disposed within the annular passage for dividing the stream of fuel passing through the passage into two parallel coaxial streams and additional secondary air is introduced into the outer stream.
Description
BACKGROUND OF THE INVENTI ON
This invention relates generally to a burner assembly and ~n~re particlllarly tc~ an improved burnex a5semb1y which operates in a manner to reduce the for~nation o nitrogen ox~des as a result of fuel c:ombustion.
Considerable attention and efforts haYe recently been directPd to the reduction of nitrogen oxides resulting from th cosnl~ustion o fuel,.and especia~ly ir~ connec:tion wi~h t~e ~;e o:~
coal an ~he furl~ace sectio~s of relatiYely large install a~ orls-10 such . a.s vapor generators and ~he li3ce. I~ a ~ypical arrang~
., . , . . , . ~or burning coal in a ~apor g~erator, se~eral bu~ ers are dis-posed in co~ i ca~ion wlth the irlterior of ~he fuxrlac~ a~d operate to burn a-mixture of air and pul~rerized coal. The burners used in these arrangemen~s are y~nerally o the type in whic~ a fuel air mixture is con~inuously ~njected ~hrough a nozzle so as ~o form a.single re1ativPly.lar~e f~ame. As a result, the surface ara~ of ~he fl~me is relativel~ small in compar~son to its volumeO and therefore the average flame ~mperature is relatively high~ ~owever, in the burning of coal, nitrosen oxides are formed by the rixation o~ atmospheri~ nitrogen available in the com-bustion supporting air, which is a function of the flame temperatu~e. When the flame temperature exceeds 2800F, th~
amount of fixed nikrogen removed from the combustion supporting air xises exponentially with increasPs in the temperature. This condition leads to the p~oduction of high levels of nitrogen oxides in the final combustion products, which causes severe air pollution proble~s.
Nitroyen oxides are also formed fro~ the fuel bound nitrogen available in the fuel itself, which is not a direct function o the flame tempe.rature, but is related to the quantity of available oxygen during the combustion process.
:~"
In view of the foregoing~ attempts have been made to suppress the burner and flame temperatures and reduce the quantity of available oxygen during the combustion process and thus reduce the formation of nitrogen oxides. Attempted solutions have included techniques involving two stage combustion, flue gas recirculation, the introduction of an oxygen-deficient fuel-air mixture to the burner and the breaking up of a single large flama into a plurality of smaller flames. However, although these attempts singularly may produce some beneficial results they have not resulted in a reduction of nitrogen oxides to minimum levels. Also, these attempts have often resulted in added expense in terms of increased construction costs and have led to other related problems such as the production of soot and the like.
SUMMARY OF THE INVENTION
The present invention seeks to provide a burner assembly which operates in a m~nner to considexably reduce the product~
ion of nitrogen oxides in the combustion of fuel without any significant increase in cost ox other related problems, and in which the surface area of the flame per unit volume is increased which results in a greater flame radiation, a lower flame temperature, and a shorter residence time of the gas component within the flame at maximum temperature.
The invention in one aspect pertains to a burner assembly comprising means defining an annular passage with an inlet located at one end of the annular passage for receiving fuel and an outlet located at the other end of the passage for discharging the fuel. Means disposed within the annular passage split up the fuel discharging from the opening so that upcn ignition of the fuel, a plurality of flame patterns are formed. A register assembly is associated with the burner, the register assembly comprising an enclosure extending over the annular passage for receiving air. Means for directing the air from the enclosure towards the outlet ~3--~7~
in two parallel paths extends around the annular passage and register means respectively are disposed in each of the paths for regulating the quantity o~ air flowing through the paths.
The invention in another aspect comprehends a burner assembly comprising means defining an annular passage with an inlet located at one end of the annular passage for re-ceiving fuel and an outlet located at the other end of the passage for discharging the fuel through the opening and into the furnace. Means disposed within the annular passage split up the fuel discharging from the opening so that upon ignition of the fuel, a plurality of flame patterns are formed. An enclosure extends around the annular passage for receiving air and a sleeve is movable across the inlet to the enclosure to vary the size of the inlet and the quantity of air entering the enclosure, the air flowing towards the outlet mixing with the fuel.
Still further~ the invention herein comprehends a burner assembly comprising an inner tubular member with an outer tubular member extending around the inner tubular member in a coaxial relation thereto to define an annular passage. An inlet is located at one end of the annular passage Eor receiving fuel and an outlet is located at the other end of the passage for discharging the fuel through the opening into the furnace. A plurality of blocks extend in a circumferentially spaced relationship in the annular passage, one end of each of the bl~ck extending in the outlet, and the other end of the blocks having a curved surface again-st which the fuel impinges. The curved surfaces direct the fuel into the spaces between the blocks for splitting up the fuel discharging from the opening so that upon ignition of the fuel, a pluxality of flame patterns are ~ormed. The blocks extend between the tubular members and are tapered in a direction from the outer tubular member to the inner tubular member.
More particularly, the burner assembly as disclosed herein includes an annular passage having an inlet located at one end thereof for receiving fuel, and an outlet located at the other end of the passage for discharging the fuel.
A plurality of members are disposed in the path of the outer stream for splitting up the stream so thatl upon ignition of the fuel, a plurality of flame patterns are formed. Secondary air is directed towards the outlet in two parallel paths extending around the burner, and a plurality of register vanes are disposed in each of the paths for regulating the quantity and swirl of the air flowing through the paths. According to an alternative embodiment, a divider cone. is disposed within the annular passage for dividing the stream of fuel passing through the passage into two parallel coaxial streams and additional secondary air is introduced into the outer stream.
-4a-~7~g~3 BRIEF DESCRIPTION OF THF DRAWINGS
Fig. 1 is a sectional view depicting the burner assembly of the present invention;
Fig. 2 is a partial perspective view of a component of the burner assembly of Fig. l;
Fig. 3 is an enlarged elevational view, partially cut-away, of the burner portion of the assembly of -the present invention;
Fig~ 4 is a perspective view of a component of the burner portion of Fig. 3;
Fig. 5 is a sectional view depicting the burner assembly according to an alternative embodiment of the present invention;
Fig. 6 is an enlarged elevational view, partially cut-away, of the nozzle of the assembly of Fig. 5;
Fig. 7 is a ~ront elevational view of the nozzle of FigO 6; and Fig. 8 is a longitudinal cross-sectional view of the nozzle of Fig. 6.
Referring in general to the embodiment of Figs.
1~4 of the drawings and specifically to Fig. 1, the reference nurneral lO refers in general to a burner assembly which is disposed i~ axial alignment with a through opening 12 forrned in a front wall 14 of a conventional fuxnace. It is understood that the furnace includes a back wall and side walls of an appropriate configuration to define a combustion chamber 16 immediately adjacent the opening 12. Also similar openings are provided in the furnace front wall 14 ~or accommodating additional burner assemblies identical to the burner assembly lO. The inner surface of the wall 14 as well as the other walls of ~he furnace are lined within an appropriate thermal insulation material 18 and, while not specifically shown, it is understood that the combustion chamber lS can also be lined with vertically extending boiler tubes through which a heat exchange fluid, such as water, is circulated in a conventional manner for the purposes of producing steam.
It is also understood that a vertical wall is disposed in a spaced parallel relationship with the furnace wall 14 in a direction opposite that of the furnace opening 12 along with correspondingly spaced top, ~ottom and side walls to form a plenum chamber, or wind box, for receiving combustion supporting air, commonly referred to as "secondary air", in a conventional manner.
The burner assembly lO includes a noæzle 20 having an inner tubular member 22 and an outer tubular member 24. The outer tubular member 24 extends over ~he inner tubular member 22 in a coaxial, spaced rela~ionship thereto to define an annular passage 26 which extends towards the furnace opening 12.
~ ~7~3 I
A tangentially disp~sed inle~ 28 co~ unica~es with the outer tubular member 24 for introduc:irg a stream of fuel into the annular passage 26 as will be explained in further detail ~ater.
~ pair af spaced annular pla~es 30 and 32 extend arour~d, the b-~lrner 20, with the inner edge of the plate 3û t~ofm;n~ting on the . outer tubular n~PTr~3er 24 . A ~i~er ~her 34 ext~ds , ~ . . . , , . : .
rom; -khe inner edge ol~ the pla~e 32 - and in a general lorlgit direc~ior~ relataYe ~o ~e burner 20 and ~ min~ es a~ac:e~t the ~sulatio~ matexial 18 jtlSt ;nci~le ~he wall 14. . A~ .
additional an~ula~ plate 38 ex.~,e~ds around {:he buI~er-20 :i~.:
a spàced, psra~lel ~elat~on wi ~ ~he plate 30. A~ air di~ider sleeve 40 eætends fro~ the inner surf~ce o~ th@
.
plate 38 and between ~he liner 34 and t~e nozzle 20 in a substan~ialiy paralle~ relatio~ to ~he burner 20 in a sub- -stantially parallel relation to the burner 20 and the li~er 34 ~o defin~ two air flow p~ssages 42 and 44~
A plurality o ou~ex regis~er vanes d6 are pi~otally moun~ed between the plates 30 and 32 t~ contro~ the swirl of secondaxy air ~rom the wind box to ~he air flow passages 42 ~nd 44. In a 5i~;1 ~r m~nner a plurali~y o~ inner register Yanes 48 are pivo.ally moun~ed between the plates 30 and 38 to further regulate the swirl of ~he secondary air passing through the annular pas~age ~4, Xt is understood ~hat although only two regîs~er vanes 4 6 and 4 8 are shown 1 n ~ig O
l, several more vanes extend in a circumferentially spaced relation to the vanes shown. Also, the pivotal mo~mtirlg of the register vanes 46 and 48 may be done in 2ny conven~ional .
manner, such as by mounting the vanes on shafts tshown-schematically in Fig. 1~ and journalling the shafts in proper bearings formed in the plate-~ 30, 3~ and 38. Also, the position of the vanes 46 and ~8 may be adjustable by means of cr~n~s or the like. Sir.ce these ty?es of compon~
ents arc conventional they are no~ shown in the drawings nor ~:ill be described in any ft~rthex (~e! ail.
The quantity of air flow from the wind box into the register vanes 46 is controlled by movement of a sleeve 50 which is slidably disposed on the outer periphery of the plate 32 and is movable parallel to the longitudinal axis of the burner burner nozzle 20. An elongated worm gear 52 is provided for mov~
ing the sleeve 50 and is better shown in Fig. ~. The worm gear 52 has one end portion s~litably connected to an appropriate drive maans (not shown~ for rotating the worm gear and the other end pro-vided with threads 52a~ The worm gear 52 extends through a bushin~
54 (Fig. 1) which is attached to the plate 30 to provide rotatable support. The threads 52a of the worm gear 52 mesh with appropriate apertures 55 formed in the sleeve 50 so that, upon rotation o the worm gear, the sleeve moves longitudinally with respect to the longitudinal axis o the burner 20 and across the air inlet defined by the plates 30 and 32. In this manner, the quantity of combus~
tion supporting air from the wind box passing through the wind box passages 42 and 44 can be controlled by axial displacement of the sleeve 50. A perforated air hood 58 extends between the plate~
30 and 32 immediately downstream of the slee~e 50 to permit the air flow to th~ burner 20 to be independently determined by means of static pressure differential movements, in a conventional ma~ner.
As shown in Fig. 3, which depicts the details of the burner nozzle 20, the end portion of the outer tubular me~ber 24 and the corresponding end portion of the inner tubular member 22 are tapered slightly radially inwardly toward the furnace open-ing 12. A plurality of divider blocks 60 are circumferentially spaced in the annular space between the tubular members 22 and 24 in the outlet end portion of the burner. As shown in FigO 3, four such blocks are spaced at 90 intervals and extend from the outlet to a point approximately midway the tapered portions of the members 22 and 24. The side portion of the blocks 60 are curved to complement the corresponcirg curved surfaces of the tubular members 22 and 24 and t-e blocks are tapered radially inwardlyO As shown .in Figure 4q.the leading end portion of each block 60 is configured in a curved xelation~
ship s~ tha~ the fuel ~lowing in the passage 26 and impinging ayainst the lead~ng ends of the bloc~s 60 will be directed into the adjacent spaces de~ined be~ween the blocks to facilitate ~h~
splitting of ~h~ ~uel stxeam in~o four separate streams.
In opexation of th~ burner assembly of ~he present inven-tion, the movable sle~ve 50 associated with each burner is ad~usted during ini~ial start up to accurately k~l~n~e the air t~ each burner. After ~he initial b~l~n~ing~ no fur~he~ move-ment of ~he slee~es 5U are needed since ~orm~l ~o~ oi o~ the .
.
seconA~ry air to ~he b~rners is accomplished by operakion of ~he outer register vanes 46.
. Fuel, preferab~y in the ~m o pulverized coal suspended or entrained within a source of primary air~ îs introduced into the tangential inlet 28 where it swirls through the annular chamber 26 and is ignited by suitable igniters (no~ ~
shown~ appropriately positioned with respect to the burner nozzle 20. The stream of.fuel and air enc~untexs the blocks - 60 at the end portion of the nozzle 20 whereby ~he 5tream is split into f our equally spaced streams which, upon ignition, form four separate flame patte~ns. The igniters are shut of~
after s~eady state combustion has been achieved and secondary air from the wind box is admitted through the perforated hood 58 and into the inlet between the plates 30 a~d 32. The axial and radial velocities of the air is con~rolled by the register vanes 46 and 48 as it passes through the air flow passage 42 and 44 and into the furnace opening 12 for mixing with the fuel from the burner 2 0 .
As a result of the foregoing, several advantages result from the burner assembly of the p-esent invention. For e.Yample, since the pressure drop across th~ ~erforated air hoods 58 asso-ciated with burne~ assemblies ca~. be e~ualized by balancing _ g _ ~7~3 the secondary air f 1QW to each burner by initially adjusting the sleeves 50, a subs~antially uniform gas distribution can be obtained across the fur~ace. This also permits a common wind box to be used and enables the unit to operate at lower excess air with sisnificant reductions in both nitrogen oxides and carbon monoxides. Also, the provision of separate register vanes 46 and 48 fo~ the outer and inner ai~ flow passages 42 and 44 enables secondary air distribution as well as flame shape to be indepe~dently controlled resulting in a significant reduction of nitrogen oxides, and a more gradual mixing of the primary air coal stream with the secondary air since both streams enter the furnace on parallel paths with controlled mixing.
Further, the provision of multiple flame patterns results in a greater flame radiation, a lower average flame temperature and a shorter residence time of the gas com-ponents within the rlame at a m~; mllm tempera~ure, all of which, as stated abo~e, contribute to r~duce the formation of nitric oxides.
Also, the use of the curved surface 60a on the blocks results in a more streamline ~low of the fuel stream before it discharges from the outlet of the nozzle 20. Still further, the provision of the tangential inlet 26 ~rovides excellent distribution of the fuel around the annular space 26 in the burner 20 resulting in more complete combustion and reduction of carbon loss and making it possible to use individual burners with capacities significantly higher than otherwise could be used.
7~3 An alternative embodiment o~ the present invention is depicted in Figs. 5 8. Referring specifically to Fig. 5 the reerence numeral 110 refers in general to a burner assembly which is dispo~ed in axial alignment with a throuyh opening 112 formed in a front wall 114 o~ a conventional furnace.
It is understood that the furnace includes a back wall and a side wall of an appropriate configuration to define a combustion chAmh~r 116 ; ~ ely adjacent ~he ope~ing 112.
Also, similar openings are provided in the furnace front wall 114 for accommodating additional burner assemblies identical to the burner assembly 10. The inner surface of the wall 114 as well as the other walls of the furnace are lined within an appropriate thermal insulation material 118 and, while not specifically shown, it is understood that the combustion chamber 116 can also be lined with boiler tubes through which a heat ex~hange fluid, such as water is circulated in a conventional manner ~or the purposes of producing steam.
It is also understood that a vertical wall is disposed in a parallel relationship with the furnace wall 14 along with connecting top, bottom, and side walls to form a plenum ch?mher, or wind box, for receiving combustion supporting air, commonly referred to as "secondary air", in a convention~l manner.
The burne~ assembly 110 includes a nozzle 120 having an inner tubular member 122 and an outer tubular member 124.
The outer tubular member 124 extends over the inner tubular member 122 in a co~xial, spaced relationship thereto to define an annular passage 126 which extends towards the furnace opening 112. A tangentially spaced inlet 128 com-municates with the outer tubular mem~ber 124 for ~ntroducing a stream of fuel and air into the annular passage 126 as will be explained in further detail later.
A pair of spaced annular plates 130 and 132 extend around the noæzle 120, with the inner edge of the plate 13~
terminating on the outer tubular member 124. A liner member 134 extends from the inner edge of the plate 132 and in a genexal longitud;n~l direction relatlve to the nozzle 120 and terminates adjacent the insulation material 11~ just inside the wall 11~. An additional annular plate 138 extends around the nozzle 120 in a spaced, parallel relation with the plate 130. An air divider sleeve 140 ex~ends from the inner surface of the plate 138 and between the liner 134 and the nozzle 120 in a substantially parallel relation to the nozzle and the liner 134 to define two air flow passages 142 and 144.
A plurality o~ outer register vanes 146 are pivotally mounted between the plates 130 and 132 to control the swirl of secondary air from the wind box to the air flow passages 142 and 144. In a similar manner a plurality of inner register vanes 148 are pivotally mounted between the plates 130 and 138 to further regulate the swirl of the secondary air passing through the annular passage 144~ It is under stood that although only two register vanes 146 and 143 are shown in Fig. 5, several more vanes extend in a ~ircum ferentially spaced relation to the vanes shown. Also, the pivotal rnounting of the vanes 146 and 143 may be done in any conventional manner, such as by mounting the v~nes on shaf~s (shown schematically~ and journallir.g the shafts in proper bearings formed in the plates 130j 132 and 138. Also, the ~0 position of the vanes 146 and 148 mav be adjustable by means of cranks or the like. Since these types of components are conventional they are not shown in the drawings nor will be described in any further detail.
It is understood that the quantity of air flow from the wind box into the vanes 146 is controlled by movement of a sleeve 150 which is slidably disposed on the outer pexiphery of the plate 132 and is mo~able parallel to t~e longitudi~al axis of the nozzle 120. This movement can be achieved by using an elongated worm gear and associated apparatu~ in a manner identical ~o that disclosed in the previous embodi-ment. Thus, the quantity of combustion supporting air from the wind box passing through the air flow passages 142 and 144 can be controlled by axial displacement of the sleeve 150. A perforated air hood 156 extends between the plates 130 and 132 ;mm~ tely downstream or the sleeve 150 to permit determination of the secondary air 10w to the burner ~s in the previous embodiment.
As shown in Figs. 6-8, which depict the details of the nozzle 120, the end portion of the outer tubular member 124 and the corres~ondiny end portion of the inner tubular mPmher 122 are tapered slightly radially inwardly toward the furnace opening 112. A divider cone 158 extends between the inner tubular member 122 and the outer tubular member 124.
The divider cone 158 has a straight portion 158a (Fig. 8) which extends between the straight portlons of inner tubular member 122 and the outer tu~ular member 124, and a tapered portion 158b which extends between the tapered portions of the tubular members for the entire lengths thereof. The function of the divider cone 158 will be described in greater detail later.
A plurality of V-shaped splitters 160 are circumferen-tially spaced in the annular space between the outer tubular member 124 and the divider cone 158 in the outlet end portion of the nozzle 120. As shown in Figs. 6 and 7, four such splitters 160 are .spaced at 90 intervals arld extend from the outlet to a po.i~t approximately midway between the tapered portions of the tubular ~m~Prs i22 and 124. Each spli~ter 160 is formed by two pla~e ~pmh~rs welded together at theix ends to ~orm a V-shape. The plate m~mh~rs are al~o welded along their respective longi~u~;n~l edges to the outer tubular mPmhP~ 124 and the divider cone 158 to support the splitters and the divider cone i~ the noz21e 120. The apex of each splitter 160 is ~isposed upstream of the nozzle outlet so that the ~uel-air stream flowing in the annular space between the divider cones 158 and the outer tubular member 124 will be directed into the adjacent spaced defined between the splitters to facilitate the splitting of the fuel.stream into four separate streams.
Four pie-shaped openings 162 are formed through the outer tubular me~er 124 and respectively extend i~mediately over the spli~ters 160. These openings are for the purpose of admltting secondary air from the inner air flow passage 144 (Fig. l) into the annular space defined between the divider cone 158 and the outer tubular member 124 for reasons that will be explained in detail later.
As shown in Fig. 8, a tip 164 is formed on the end of the tapered portion of the inner tubular member 122 and is movable relative to the latter member by means of a ~lurality of rods 166 extending within the tubular member and affixed ~ca7~3 to the inner wall of the tip. The other ends of the rods 166 can be connected to any type of actuator device (not shown) such as hydrauli cylinder or the like to effect longitudinal movement of the rods and therefore the tip 164 in a conventional manner.
It ~an be appreciated from a view of Fig. ~ that the longit~l~in~l l"o~ le~lt of the tip 164 varies the effeckive outlet opening defined between the tip and the divider cone 158 so that the amount of fuel-air flowing through this opening can be regulated. Since the divider cone 158 divides the fuel-air mixture flowing through the annular passage 126 into two radially spaced parallel streams extending to either side of the divider cone 158, it can be appreciated that movement of the tip 164 regulates the relative flow of the two streams while varying their velocity.
It is understood that appropriate igniters can be provided adjacent the outlet of the no7zle 120 for igniting the coal as it discharges from the noz21e. Since these igniters are of a conventional desisn they have not been shown in the drawings in the interest of clarity.
In operation of the embodiment of Figs. 5-8, the movable sleeve 150 associated with each burner is adjusted during initial start up to accurately balance the air to each burner. After the initial balancing, no further movement of the sleeves 150 are needed since normal control of the secondary air flow to the buxners is accomplished by operation of the outer burner vanes 146. However, if desired, flow control can be accomplished by the sleeve.
Fuel, preferably in the form of pulverized coal suspended or entrained within a source of primary air, is introduced into the tangential inlet 128 where i~ swirls through the annular chamber 126. Since the pulverized coal introduced into the inlet 12~ is heavier than th~ air, the pulverized coal will tend to mova radially ~utwardly towards the inner wall of the outer tubular member 124 under the centrifugal orces thus produced. As a result, a great majoxity of the coal along with a relatively small portion of air enters the outer a~nular pas~age defined between the outex tubular member 124 and the divider cone 158 (Fig. 8) where it encounters the apexes of the splitters 160. The stream i5 thus split into four equally spaced streams which discharge from the nozzle outlet and, upon ignition, form four sep~rate flame patterns. Secondary air from the inner air passage 14~ (Fig. 5) passes through the inlets 162 formed in the outer tubular member 124 and enters the annular passage between the latter member and the divider cone 158 to supply secondary air to the streams of coal and air discharging from the outlet.
The remaining portion of the air-coal mixture passing through the annular passage 126 enter~ the annular passa~e defined between the divider cone 158 and khe inner tubular member 122. The mixture entering this annular passage is mostly air due to the movement of the coal radially outwardly, as described above. The position of the movable tip 164 can be adjus~ed to precisely control the relative amount, and therefore velocity, of the air and coal discharging from the noæzle 120 from the annular passages between the outer tubular member 124 and the divider cone 158 and between the divider cone and ~he inner tubular member 122.
Secondary air from the wind box is admitted through the perforated hood 156 and into the inlet between the plates 130 and 132. The axial and radial velocities of the air are controlled by the register vanes 146 and 148 as it passes through the air flow passages 142 and 144 and into the furnace opening 112 for mixing with ~he coal from the nozzle i20. The igniters are then shut off after steady state oom bustion has been achieved.
As a result of the foregoing, several ad~antages result from the burner assembly of he present invention. For example, since the pressure drop across the perforated air hoods 156 associated with the burner assemblies can be equalized by balancing the secondary air flow to each burner by initially adjusting thP sleeves 150, a substant ially u~ifoxm flue gas distribution can be obtained across the furnace. This also permits a common wind box to be used and enables the unit to operate at lower excess air with significant reductions in both nitrogen oxides and carbon monoxides. Also, the prcvision or separate register vanes 146 and 148 for the outer and inner air flow passages 142 and 144 enables secondary air distribution and flame shape to be independently controlled resulting in a significan~
reduction of r.itrogen oxides, and a more gradual mixing of the primary air coal stream with the secondary air since both streams enter the furnace on parallel paths with controlled mixing.
Further, the provision of multiple flame patterns ~7~3 results in a greater flame radiation, a lower average flame temperature and a shorter residence time of the gas components within the flame at a maximum temperature, all of which, as stated above, contribute to reduce the formation of nitric oxides.
Still fuxther, the provision of the tangential inlet 126 provides excellen~ distribution of the fuel around the annular space 126 in the nozzle 120, resulting in more complete combustion and reduction of carbon loss and making it possible to use individual burners with capacities significantly higher than otherwi~e could be used. Pro-vision of the inlet openings 162 in the outer tubular membex permits the introduction of a portion of the secondary air to be entrained with the fuei~air stream passing through the annular passage between the outer tubular member 124 and the divider cone, since the majority of this stream will be primarily pulverized coal. As a resul~, a substantially uniform air-coal ratio across the entire cross-section of the air-coal stream is achievea. Also, the provision of the movable tip 164 to regulate the flow of the coal-air mixture passing through the inner annular passage derined between the divider cone 158 and the inner tubular member 122 enables the air flow on both sides of the divider cone to be regulated thereby optimizing the primary air veiocity with respect to the secondary air velocity.
It is understood that several variations and additions may be made to both embodimen~s of ~he prevent invention within the scope of the invention. For example, since the arrangement of ~he present invention permits the admission 7~3 of air at less than stoichiometric, over~ire air ports, or the like can be provided as needed to supply air to complete the combustion.
As will be apparent to ~hose skilled in the art, other changes and modifications may be made to the e~bodime~ts of the present invention without departing from the spirt and scope of the present invention as defined in the appended claims and the legal equivalentO
This invention relates generally to a burner assembly and ~n~re particlllarly tc~ an improved burnex a5semb1y which operates in a manner to reduce the for~nation o nitrogen ox~des as a result of fuel c:ombustion.
Considerable attention and efforts haYe recently been directPd to the reduction of nitrogen oxides resulting from th cosnl~ustion o fuel,.and especia~ly ir~ connec:tion wi~h t~e ~;e o:~
coal an ~he furl~ace sectio~s of relatiYely large install a~ orls-10 such . a.s vapor generators and ~he li3ce. I~ a ~ypical arrang~
., . , . . , . ~or burning coal in a ~apor g~erator, se~eral bu~ ers are dis-posed in co~ i ca~ion wlth the irlterior of ~he fuxrlac~ a~d operate to burn a-mixture of air and pul~rerized coal. The burners used in these arrangemen~s are y~nerally o the type in whic~ a fuel air mixture is con~inuously ~njected ~hrough a nozzle so as ~o form a.single re1ativPly.lar~e f~ame. As a result, the surface ara~ of ~he fl~me is relativel~ small in compar~son to its volumeO and therefore the average flame ~mperature is relatively high~ ~owever, in the burning of coal, nitrosen oxides are formed by the rixation o~ atmospheri~ nitrogen available in the com-bustion supporting air, which is a function of the flame temperatu~e. When the flame temperature exceeds 2800F, th~
amount of fixed nikrogen removed from the combustion supporting air xises exponentially with increasPs in the temperature. This condition leads to the p~oduction of high levels of nitrogen oxides in the final combustion products, which causes severe air pollution proble~s.
Nitroyen oxides are also formed fro~ the fuel bound nitrogen available in the fuel itself, which is not a direct function o the flame tempe.rature, but is related to the quantity of available oxygen during the combustion process.
:~"
In view of the foregoing~ attempts have been made to suppress the burner and flame temperatures and reduce the quantity of available oxygen during the combustion process and thus reduce the formation of nitrogen oxides. Attempted solutions have included techniques involving two stage combustion, flue gas recirculation, the introduction of an oxygen-deficient fuel-air mixture to the burner and the breaking up of a single large flama into a plurality of smaller flames. However, although these attempts singularly may produce some beneficial results they have not resulted in a reduction of nitrogen oxides to minimum levels. Also, these attempts have often resulted in added expense in terms of increased construction costs and have led to other related problems such as the production of soot and the like.
SUMMARY OF THE INVENTION
The present invention seeks to provide a burner assembly which operates in a m~nner to considexably reduce the product~
ion of nitrogen oxides in the combustion of fuel without any significant increase in cost ox other related problems, and in which the surface area of the flame per unit volume is increased which results in a greater flame radiation, a lower flame temperature, and a shorter residence time of the gas component within the flame at maximum temperature.
The invention in one aspect pertains to a burner assembly comprising means defining an annular passage with an inlet located at one end of the annular passage for receiving fuel and an outlet located at the other end of the passage for discharging the fuel. Means disposed within the annular passage split up the fuel discharging from the opening so that upcn ignition of the fuel, a plurality of flame patterns are formed. A register assembly is associated with the burner, the register assembly comprising an enclosure extending over the annular passage for receiving air. Means for directing the air from the enclosure towards the outlet ~3--~7~
in two parallel paths extends around the annular passage and register means respectively are disposed in each of the paths for regulating the quantity o~ air flowing through the paths.
The invention in another aspect comprehends a burner assembly comprising means defining an annular passage with an inlet located at one end of the annular passage for re-ceiving fuel and an outlet located at the other end of the passage for discharging the fuel through the opening and into the furnace. Means disposed within the annular passage split up the fuel discharging from the opening so that upon ignition of the fuel, a plurality of flame patterns are formed. An enclosure extends around the annular passage for receiving air and a sleeve is movable across the inlet to the enclosure to vary the size of the inlet and the quantity of air entering the enclosure, the air flowing towards the outlet mixing with the fuel.
Still further~ the invention herein comprehends a burner assembly comprising an inner tubular member with an outer tubular member extending around the inner tubular member in a coaxial relation thereto to define an annular passage. An inlet is located at one end of the annular passage Eor receiving fuel and an outlet is located at the other end of the passage for discharging the fuel through the opening into the furnace. A plurality of blocks extend in a circumferentially spaced relationship in the annular passage, one end of each of the bl~ck extending in the outlet, and the other end of the blocks having a curved surface again-st which the fuel impinges. The curved surfaces direct the fuel into the spaces between the blocks for splitting up the fuel discharging from the opening so that upon ignition of the fuel, a pluxality of flame patterns are ~ormed. The blocks extend between the tubular members and are tapered in a direction from the outer tubular member to the inner tubular member.
More particularly, the burner assembly as disclosed herein includes an annular passage having an inlet located at one end thereof for receiving fuel, and an outlet located at the other end of the passage for discharging the fuel.
A plurality of members are disposed in the path of the outer stream for splitting up the stream so thatl upon ignition of the fuel, a plurality of flame patterns are formed. Secondary air is directed towards the outlet in two parallel paths extending around the burner, and a plurality of register vanes are disposed in each of the paths for regulating the quantity and swirl of the air flowing through the paths. According to an alternative embodiment, a divider cone. is disposed within the annular passage for dividing the stream of fuel passing through the passage into two parallel coaxial streams and additional secondary air is introduced into the outer stream.
-4a-~7~g~3 BRIEF DESCRIPTION OF THF DRAWINGS
Fig. 1 is a sectional view depicting the burner assembly of the present invention;
Fig. 2 is a partial perspective view of a component of the burner assembly of Fig. l;
Fig. 3 is an enlarged elevational view, partially cut-away, of the burner portion of the assembly of -the present invention;
Fig~ 4 is a perspective view of a component of the burner portion of Fig. 3;
Fig. 5 is a sectional view depicting the burner assembly according to an alternative embodiment of the present invention;
Fig. 6 is an enlarged elevational view, partially cut-away, of the nozzle of the assembly of Fig. 5;
Fig. 7 is a ~ront elevational view of the nozzle of FigO 6; and Fig. 8 is a longitudinal cross-sectional view of the nozzle of Fig. 6.
Referring in general to the embodiment of Figs.
1~4 of the drawings and specifically to Fig. 1, the reference nurneral lO refers in general to a burner assembly which is disposed i~ axial alignment with a through opening 12 forrned in a front wall 14 of a conventional fuxnace. It is understood that the furnace includes a back wall and side walls of an appropriate configuration to define a combustion chamber 16 immediately adjacent the opening 12. Also similar openings are provided in the furnace front wall 14 ~or accommodating additional burner assemblies identical to the burner assembly lO. The inner surface of the wall 14 as well as the other walls of ~he furnace are lined within an appropriate thermal insulation material 18 and, while not specifically shown, it is understood that the combustion chamber lS can also be lined with vertically extending boiler tubes through which a heat exchange fluid, such as water, is circulated in a conventional manner for the purposes of producing steam.
It is also understood that a vertical wall is disposed in a spaced parallel relationship with the furnace wall 14 in a direction opposite that of the furnace opening 12 along with correspondingly spaced top, ~ottom and side walls to form a plenum chamber, or wind box, for receiving combustion supporting air, commonly referred to as "secondary air", in a conventional manner.
The burner assembly lO includes a noæzle 20 having an inner tubular member 22 and an outer tubular member 24. The outer tubular member 24 extends over ~he inner tubular member 22 in a coaxial, spaced rela~ionship thereto to define an annular passage 26 which extends towards the furnace opening 12.
~ ~7~3 I
A tangentially disp~sed inle~ 28 co~ unica~es with the outer tubular member 24 for introduc:irg a stream of fuel into the annular passage 26 as will be explained in further detail ~ater.
~ pair af spaced annular pla~es 30 and 32 extend arour~d, the b-~lrner 20, with the inner edge of the plate 3û t~ofm;n~ting on the . outer tubular n~PTr~3er 24 . A ~i~er ~her 34 ext~ds , ~ . . . , , . : .
rom; -khe inner edge ol~ the pla~e 32 - and in a general lorlgit direc~ior~ relataYe ~o ~e burner 20 and ~ min~ es a~ac:e~t the ~sulatio~ matexial 18 jtlSt ;nci~le ~he wall 14. . A~ .
additional an~ula~ plate 38 ex.~,e~ds around {:he buI~er-20 :i~.:
a spàced, psra~lel ~elat~on wi ~ ~he plate 30. A~ air di~ider sleeve 40 eætends fro~ the inner surf~ce o~ th@
.
plate 38 and between ~he liner 34 and t~e nozzle 20 in a substan~ialiy paralle~ relatio~ to ~he burner 20 in a sub- -stantially parallel relation to the burner 20 and the li~er 34 ~o defin~ two air flow p~ssages 42 and 44~
A plurality o ou~ex regis~er vanes d6 are pi~otally moun~ed between the plates 30 and 32 t~ contro~ the swirl of secondaxy air ~rom the wind box to ~he air flow passages 42 ~nd 44. In a 5i~;1 ~r m~nner a plurali~y o~ inner register Yanes 48 are pivo.ally moun~ed between the plates 30 and 38 to further regulate the swirl of ~he secondary air passing through the annular pas~age ~4, Xt is understood ~hat although only two regîs~er vanes 4 6 and 4 8 are shown 1 n ~ig O
l, several more vanes extend in a circumferentially spaced relation to the vanes shown. Also, the pivotal mo~mtirlg of the register vanes 46 and 48 may be done in 2ny conven~ional .
manner, such as by mounting the vanes on shafts tshown-schematically in Fig. 1~ and journalling the shafts in proper bearings formed in the plate-~ 30, 3~ and 38. Also, the position of the vanes 46 and ~8 may be adjustable by means of cr~n~s or the like. Sir.ce these ty?es of compon~
ents arc conventional they are no~ shown in the drawings nor ~:ill be described in any ft~rthex (~e! ail.
The quantity of air flow from the wind box into the register vanes 46 is controlled by movement of a sleeve 50 which is slidably disposed on the outer periphery of the plate 32 and is movable parallel to the longitudinal axis of the burner burner nozzle 20. An elongated worm gear 52 is provided for mov~
ing the sleeve 50 and is better shown in Fig. ~. The worm gear 52 has one end portion s~litably connected to an appropriate drive maans (not shown~ for rotating the worm gear and the other end pro-vided with threads 52a~ The worm gear 52 extends through a bushin~
54 (Fig. 1) which is attached to the plate 30 to provide rotatable support. The threads 52a of the worm gear 52 mesh with appropriate apertures 55 formed in the sleeve 50 so that, upon rotation o the worm gear, the sleeve moves longitudinally with respect to the longitudinal axis o the burner 20 and across the air inlet defined by the plates 30 and 32. In this manner, the quantity of combus~
tion supporting air from the wind box passing through the wind box passages 42 and 44 can be controlled by axial displacement of the sleeve 50. A perforated air hood 58 extends between the plate~
30 and 32 immediately downstream of the slee~e 50 to permit the air flow to th~ burner 20 to be independently determined by means of static pressure differential movements, in a conventional ma~ner.
As shown in Fig. 3, which depicts the details of the burner nozzle 20, the end portion of the outer tubular me~ber 24 and the corresponding end portion of the inner tubular member 22 are tapered slightly radially inwardly toward the furnace open-ing 12. A plurality of divider blocks 60 are circumferentially spaced in the annular space between the tubular members 22 and 24 in the outlet end portion of the burner. As shown in FigO 3, four such blocks are spaced at 90 intervals and extend from the outlet to a point approximately midway the tapered portions of the members 22 and 24. The side portion of the blocks 60 are curved to complement the corresponcirg curved surfaces of the tubular members 22 and 24 and t-e blocks are tapered radially inwardlyO As shown .in Figure 4q.the leading end portion of each block 60 is configured in a curved xelation~
ship s~ tha~ the fuel ~lowing in the passage 26 and impinging ayainst the lead~ng ends of the bloc~s 60 will be directed into the adjacent spaces de~ined be~ween the blocks to facilitate ~h~
splitting of ~h~ ~uel stxeam in~o four separate streams.
In opexation of th~ burner assembly of ~he present inven-tion, the movable sle~ve 50 associated with each burner is ad~usted during ini~ial start up to accurately k~l~n~e the air t~ each burner. After ~he initial b~l~n~ing~ no fur~he~ move-ment of ~he slee~es 5U are needed since ~orm~l ~o~ oi o~ the .
.
seconA~ry air to ~he b~rners is accomplished by operakion of ~he outer register vanes 46.
. Fuel, preferab~y in the ~m o pulverized coal suspended or entrained within a source of primary air~ îs introduced into the tangential inlet 28 where it swirls through the annular chamber 26 and is ignited by suitable igniters (no~ ~
shown~ appropriately positioned with respect to the burner nozzle 20. The stream of.fuel and air enc~untexs the blocks - 60 at the end portion of the nozzle 20 whereby ~he 5tream is split into f our equally spaced streams which, upon ignition, form four separate flame patte~ns. The igniters are shut of~
after s~eady state combustion has been achieved and secondary air from the wind box is admitted through the perforated hood 58 and into the inlet between the plates 30 a~d 32. The axial and radial velocities of the air is con~rolled by the register vanes 46 and 48 as it passes through the air flow passage 42 and 44 and into the furnace opening 12 for mixing with the fuel from the burner 2 0 .
As a result of the foregoing, several advantages result from the burner assembly of the p-esent invention. For e.Yample, since the pressure drop across th~ ~erforated air hoods 58 asso-ciated with burne~ assemblies ca~. be e~ualized by balancing _ g _ ~7~3 the secondary air f 1QW to each burner by initially adjusting the sleeves 50, a subs~antially uniform gas distribution can be obtained across the fur~ace. This also permits a common wind box to be used and enables the unit to operate at lower excess air with sisnificant reductions in both nitrogen oxides and carbon monoxides. Also, the provision of separate register vanes 46 and 48 fo~ the outer and inner ai~ flow passages 42 and 44 enables secondary air distribution as well as flame shape to be indepe~dently controlled resulting in a significant reduction of nitrogen oxides, and a more gradual mixing of the primary air coal stream with the secondary air since both streams enter the furnace on parallel paths with controlled mixing.
Further, the provision of multiple flame patterns results in a greater flame radiation, a lower average flame temperature and a shorter residence time of the gas com-ponents within the rlame at a m~; mllm tempera~ure, all of which, as stated abo~e, contribute to r~duce the formation of nitric oxides.
Also, the use of the curved surface 60a on the blocks results in a more streamline ~low of the fuel stream before it discharges from the outlet of the nozzle 20. Still further, the provision of the tangential inlet 26 ~rovides excellent distribution of the fuel around the annular space 26 in the burner 20 resulting in more complete combustion and reduction of carbon loss and making it possible to use individual burners with capacities significantly higher than otherwise could be used.
7~3 An alternative embodiment o~ the present invention is depicted in Figs. 5 8. Referring specifically to Fig. 5 the reerence numeral 110 refers in general to a burner assembly which is dispo~ed in axial alignment with a throuyh opening 112 formed in a front wall 114 o~ a conventional furnace.
It is understood that the furnace includes a back wall and a side wall of an appropriate configuration to define a combustion chAmh~r 116 ; ~ ely adjacent ~he ope~ing 112.
Also, similar openings are provided in the furnace front wall 114 for accommodating additional burner assemblies identical to the burner assembly 10. The inner surface of the wall 114 as well as the other walls of the furnace are lined within an appropriate thermal insulation material 118 and, while not specifically shown, it is understood that the combustion chamber 116 can also be lined with boiler tubes through which a heat ex~hange fluid, such as water is circulated in a conventional manner ~or the purposes of producing steam.
It is also understood that a vertical wall is disposed in a parallel relationship with the furnace wall 14 along with connecting top, bottom, and side walls to form a plenum ch?mher, or wind box, for receiving combustion supporting air, commonly referred to as "secondary air", in a convention~l manner.
The burne~ assembly 110 includes a nozzle 120 having an inner tubular member 122 and an outer tubular member 124.
The outer tubular member 124 extends over the inner tubular member 122 in a co~xial, spaced relationship thereto to define an annular passage 126 which extends towards the furnace opening 112. A tangentially spaced inlet 128 com-municates with the outer tubular mem~ber 124 for ~ntroducing a stream of fuel and air into the annular passage 126 as will be explained in further detail later.
A pair of spaced annular plates 130 and 132 extend around the noæzle 120, with the inner edge of the plate 13~
terminating on the outer tubular member 124. A liner member 134 extends from the inner edge of the plate 132 and in a genexal longitud;n~l direction relatlve to the nozzle 120 and terminates adjacent the insulation material 11~ just inside the wall 11~. An additional annular plate 138 extends around the nozzle 120 in a spaced, parallel relation with the plate 130. An air divider sleeve 140 ex~ends from the inner surface of the plate 138 and between the liner 134 and the nozzle 120 in a substantially parallel relation to the nozzle and the liner 134 to define two air flow passages 142 and 144.
A plurality o~ outer register vanes 146 are pivotally mounted between the plates 130 and 132 to control the swirl of secondary air from the wind box to the air flow passages 142 and 144. In a similar manner a plurality of inner register vanes 148 are pivotally mounted between the plates 130 and 138 to further regulate the swirl of the secondary air passing through the annular passage 144~ It is under stood that although only two register vanes 146 and 143 are shown in Fig. 5, several more vanes extend in a ~ircum ferentially spaced relation to the vanes shown. Also, the pivotal rnounting of the vanes 146 and 143 may be done in any conventional manner, such as by mounting the v~nes on shaf~s (shown schematically~ and journallir.g the shafts in proper bearings formed in the plates 130j 132 and 138. Also, the ~0 position of the vanes 146 and 148 mav be adjustable by means of cranks or the like. Since these types of components are conventional they are not shown in the drawings nor will be described in any further detail.
It is understood that the quantity of air flow from the wind box into the vanes 146 is controlled by movement of a sleeve 150 which is slidably disposed on the outer pexiphery of the plate 132 and is mo~able parallel to t~e longitudi~al axis of the nozzle 120. This movement can be achieved by using an elongated worm gear and associated apparatu~ in a manner identical ~o that disclosed in the previous embodi-ment. Thus, the quantity of combustion supporting air from the wind box passing through the air flow passages 142 and 144 can be controlled by axial displacement of the sleeve 150. A perforated air hood 156 extends between the plates 130 and 132 ;mm~ tely downstream or the sleeve 150 to permit determination of the secondary air 10w to the burner ~s in the previous embodiment.
As shown in Figs. 6-8, which depict the details of the nozzle 120, the end portion of the outer tubular member 124 and the corres~ondiny end portion of the inner tubular mPmher 122 are tapered slightly radially inwardly toward the furnace opening 112. A divider cone 158 extends between the inner tubular member 122 and the outer tubular member 124.
The divider cone 158 has a straight portion 158a (Fig. 8) which extends between the straight portlons of inner tubular member 122 and the outer tu~ular member 124, and a tapered portion 158b which extends between the tapered portions of the tubular members for the entire lengths thereof. The function of the divider cone 158 will be described in greater detail later.
A plurality of V-shaped splitters 160 are circumferen-tially spaced in the annular space between the outer tubular member 124 and the divider cone 158 in the outlet end portion of the nozzle 120. As shown in Figs. 6 and 7, four such splitters 160 are .spaced at 90 intervals arld extend from the outlet to a po.i~t approximately midway between the tapered portions of the tubular ~m~Prs i22 and 124. Each spli~ter 160 is formed by two pla~e ~pmh~rs welded together at theix ends to ~orm a V-shape. The plate m~mh~rs are al~o welded along their respective longi~u~;n~l edges to the outer tubular mPmhP~ 124 and the divider cone 158 to support the splitters and the divider cone i~ the noz21e 120. The apex of each splitter 160 is ~isposed upstream of the nozzle outlet so that the ~uel-air stream flowing in the annular space between the divider cones 158 and the outer tubular member 124 will be directed into the adjacent spaced defined between the splitters to facilitate the splitting of the fuel.stream into four separate streams.
Four pie-shaped openings 162 are formed through the outer tubular me~er 124 and respectively extend i~mediately over the spli~ters 160. These openings are for the purpose of admltting secondary air from the inner air flow passage 144 (Fig. l) into the annular space defined between the divider cone 158 and the outer tubular member 124 for reasons that will be explained in detail later.
As shown in Fig. 8, a tip 164 is formed on the end of the tapered portion of the inner tubular member 122 and is movable relative to the latter member by means of a ~lurality of rods 166 extending within the tubular member and affixed ~ca7~3 to the inner wall of the tip. The other ends of the rods 166 can be connected to any type of actuator device (not shown) such as hydrauli cylinder or the like to effect longitudinal movement of the rods and therefore the tip 164 in a conventional manner.
It ~an be appreciated from a view of Fig. ~ that the longit~l~in~l l"o~ le~lt of the tip 164 varies the effeckive outlet opening defined between the tip and the divider cone 158 so that the amount of fuel-air flowing through this opening can be regulated. Since the divider cone 158 divides the fuel-air mixture flowing through the annular passage 126 into two radially spaced parallel streams extending to either side of the divider cone 158, it can be appreciated that movement of the tip 164 regulates the relative flow of the two streams while varying their velocity.
It is understood that appropriate igniters can be provided adjacent the outlet of the no7zle 120 for igniting the coal as it discharges from the noz21e. Since these igniters are of a conventional desisn they have not been shown in the drawings in the interest of clarity.
In operation of the embodiment of Figs. 5-8, the movable sleeve 150 associated with each burner is adjusted during initial start up to accurately balance the air to each burner. After the initial balancing, no further movement of the sleeves 150 are needed since normal control of the secondary air flow to the buxners is accomplished by operation of the outer burner vanes 146. However, if desired, flow control can be accomplished by the sleeve.
Fuel, preferably in the form of pulverized coal suspended or entrained within a source of primary air, is introduced into the tangential inlet 128 where i~ swirls through the annular chamber 126. Since the pulverized coal introduced into the inlet 12~ is heavier than th~ air, the pulverized coal will tend to mova radially ~utwardly towards the inner wall of the outer tubular member 124 under the centrifugal orces thus produced. As a result, a great majoxity of the coal along with a relatively small portion of air enters the outer a~nular pas~age defined between the outex tubular member 124 and the divider cone 158 (Fig. 8) where it encounters the apexes of the splitters 160. The stream i5 thus split into four equally spaced streams which discharge from the nozzle outlet and, upon ignition, form four sep~rate flame patterns. Secondary air from the inner air passage 14~ (Fig. 5) passes through the inlets 162 formed in the outer tubular member 124 and enters the annular passage between the latter member and the divider cone 158 to supply secondary air to the streams of coal and air discharging from the outlet.
The remaining portion of the air-coal mixture passing through the annular passage 126 enter~ the annular passa~e defined between the divider cone 158 and khe inner tubular member 122. The mixture entering this annular passage is mostly air due to the movement of the coal radially outwardly, as described above. The position of the movable tip 164 can be adjus~ed to precisely control the relative amount, and therefore velocity, of the air and coal discharging from the noæzle 120 from the annular passages between the outer tubular member 124 and the divider cone 158 and between the divider cone and ~he inner tubular member 122.
Secondary air from the wind box is admitted through the perforated hood 156 and into the inlet between the plates 130 and 132. The axial and radial velocities of the air are controlled by the register vanes 146 and 148 as it passes through the air flow passages 142 and 144 and into the furnace opening 112 for mixing with ~he coal from the nozzle i20. The igniters are then shut off after steady state oom bustion has been achieved.
As a result of the foregoing, several ad~antages result from the burner assembly of he present invention. For example, since the pressure drop across the perforated air hoods 156 associated with the burner assemblies can be equalized by balancing the secondary air flow to each burner by initially adjusting thP sleeves 150, a substant ially u~ifoxm flue gas distribution can be obtained across the furnace. This also permits a common wind box to be used and enables the unit to operate at lower excess air with significant reductions in both nitrogen oxides and carbon monoxides. Also, the prcvision or separate register vanes 146 and 148 for the outer and inner air flow passages 142 and 144 enables secondary air distribution and flame shape to be independently controlled resulting in a significan~
reduction of r.itrogen oxides, and a more gradual mixing of the primary air coal stream with the secondary air since both streams enter the furnace on parallel paths with controlled mixing.
Further, the provision of multiple flame patterns ~7~3 results in a greater flame radiation, a lower average flame temperature and a shorter residence time of the gas components within the flame at a maximum temperature, all of which, as stated above, contribute to reduce the formation of nitric oxides.
Still fuxther, the provision of the tangential inlet 126 provides excellen~ distribution of the fuel around the annular space 126 in the nozzle 120, resulting in more complete combustion and reduction of carbon loss and making it possible to use individual burners with capacities significantly higher than otherwi~e could be used. Pro-vision of the inlet openings 162 in the outer tubular membex permits the introduction of a portion of the secondary air to be entrained with the fuei~air stream passing through the annular passage between the outer tubular member 124 and the divider cone, since the majority of this stream will be primarily pulverized coal. As a resul~, a substantially uniform air-coal ratio across the entire cross-section of the air-coal stream is achievea. Also, the provision of the movable tip 164 to regulate the flow of the coal-air mixture passing through the inner annular passage derined between the divider cone 158 and the inner tubular member 122 enables the air flow on both sides of the divider cone to be regulated thereby optimizing the primary air veiocity with respect to the secondary air velocity.
It is understood that several variations and additions may be made to both embodimen~s of ~he prevent invention within the scope of the invention. For example, since the arrangement of ~he present invention permits the admission 7~3 of air at less than stoichiometric, over~ire air ports, or the like can be provided as needed to supply air to complete the combustion.
As will be apparent to ~hose skilled in the art, other changes and modifications may be made to the e~bodime~ts of the present invention without departing from the spirt and scope of the present invention as defined in the appended claims and the legal equivalentO
Claims (19)
1. A burner assembly comprising means defining an annular passage, an inlet located at one end of said annular passage for receiving fuel, and an outlet located at the other end of said passage for discharging said fuel; means disposed within said annular passage for splitting up the fuel discharging from said opening so that upon ignition of said fuel, a plurality of flame patterns are formed; and a register assembly associated with said burner, said register assembly comprising an enclosure extending over said annular passage for receiving air, means for directing said air from said enclosure towards said outlet in two parallel paths extending around said annular passage and register means respectively disposed in each of said paths for regulating the quantity of air flowing through said paths.
2. The burner assembly of claim 1 wherein said passage defining means comprises an inner tubular member and an outer tubular member extending around said inner tubular member in a coaxial relation thereto.
3. The burner assembly of claim 1 or 2 further com-prising means for directing fuel through said inlet and into said annular space in a tangential direction relative to said annular space.
4. The burner assembly of claim 1 further comprising means for regulating the quantity of air entering said enclosure.
5. The burner assembly of claim 4 wherein said latter regulating means comprises a sleeve movable across the inlet to said enclosure to vary the size of said inlet.
6. The burner assembly of Claim 1 wherein said splitting means comprises a plurality of blocks extending in a circumferentially spaced relationship in said annular passage, one end of each of said blocks extending in said outlet, and the other end of each of said blocks having a curved surface against which said fuel impinges, said curved surfaces directing said fuel into the spaces between said blocks.
7. The burner assembly of Claim 6 wherein said passage defining means comprises an inner tubular member and an outer tubular member extending around said inner tubular member in a coaxial relation thereto, and wherein said blocks extend between said tubular members and are tapered in a direction from said outer tubular member to said inner tubular member.
8. A burner assembly comprising means defining an annular passage, an inlet located at one end of said annular passage for receiving fuel, and an outlet located at the other end of said passage for discharging said fuel through said opening and into said furnace; means disposed within said annular passage for splitting up the fuel discharging from said opening so that upon ignition of said fuel, a plurality of flame patterns are formed, an enclosure extending around said annular passage for receiving air; and a sleeve movable across the inlet to said enclosure to vary the size of said inlet and the quantity of air entering said enclosure, said air flowing towards said outlet for mixing with said fuel.
9. The burner assembly of Claim 8 further comprising a perforated hood extending across said enclosure inlet and cooperating with said movable sleeve to vary the size of said inlet and the quantity of air entering said enclosure.
10. The burner assembly of claim 9 further comprising means disposed within said enclosure for direction said air from said enclosure towards said outlet in two parallel paths extending around said annular passage, and register means respectively disposed in each of said paths for regulation the quantity of air flowing through said paths.
11. The burner assembly of claim 8 wherein said passage defining means comprises an inner tubular member and an outlet tubular member extending around said inner tubular member in a coaxial relation thereto.
12. The burner assembly of claim 8 or 11 further comprising means for directing fuel through said inlet and into said annular space in a tangential direction relative to said annular space.
13. The burner assembly of claim 8 wherein said splitting means comprises a plurality of blocks extending in a circumferentially spaced relationship in said annular passage, one end of each of said blocks having a curved surface against which said fuel impinges, said curved surfaces directing said fuel into the spaced between said blocks,
14. The burner assembly of claim 13 wherein said passage defining means comprises an inner tubular member and an outer tubular member extending around said inner tubular member in a coaxial relation thereto. and wherein said blocks extend between said tubular members and are tapered in a direction from said outer tubular member to said inner tubular member.
15. A burner assembly comprising an inner tubular member; an outer tubular member extending around said inner tubular member in a coaxial relation thereto to define an annular passage; an inlet located at one end of said annular passage for receiving fuel, an outlet located at the other end of said passage for discharging said fuel through said opening into said furnace; and a plurality of blocks extending in a circumferentially spaced relationship in said annular passage, one end of each of said blocks extending in said outlet, and the other end of said blocks having a curved surface against which said fuel impinges, said curved surfaces directing said fuel into the spaces between said blocks for splitting up the fuel discharging from said opening so-that upon ignition of said fuel, a plurality of flame patterns are formed, said blocks extending between said tubular members and being tapered in a direction from said outer tubular member to said inner tubular member.
16. The burner assembly of claim 15 further comprising an enclosure extending around said tubular members for receiving air, means for directing said air from said enclosure towards said outlet in two parallel paths extending around said tubular members, and register means respectively disposed in each of said paths for regulating the quantity of air flowing through said paths.
17. The burner assembly of claim 15 further comprising means for directing fuel through said inlet and into said annular sapce in a tangential direction relative to said annular space.
18. The burner assembly of claim 15 further comprising means for regulating the quantity of air entering said enclosure.
19. The burner assembly of claim 4 wherein said latter regulating means comprises a sleeve movable across the inlet to said enclosure to vary the size of said inlet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000480770A CA1204342A (en) | 1980-06-04 | 1985-05-03 | Dual register, split stream burner assembly |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15630880A | 1980-06-04 | 1980-06-04 | |
| US156,309 | 1980-06-04 | ||
| US156,308 | 1980-06-04 | ||
| US06/156,309 US4348170A (en) | 1980-06-04 | 1980-06-04 | Dual register, split stream burner assembly with divider cone |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000480770A Division CA1204342A (en) | 1980-06-04 | 1985-05-03 | Dual register, split stream burner assembly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1197143A true CA1197143A (en) | 1985-11-26 |
Family
ID=26853054
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000378443A Expired CA1197143A (en) | 1980-06-04 | 1981-05-27 | Dual register, split stream burner assembly |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU545781B2 (en) |
| CA (1) | CA1197143A (en) |
| ES (1) | ES502789A0 (en) |
| GB (2) | GB2079925B (en) |
| MX (1) | MX153659A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2276715B (en) * | 1993-03-29 | 1995-10-04 | Yue Stoves Manufactory Limited | Gas burner |
| DK172645B1 (en) * | 1996-09-09 | 1999-03-29 | Burmeister & Wains As | Windbox burner |
| CN108506935A (en) * | 2018-05-28 | 2018-09-07 | 杭州浙大天元科技有限公司 | Based on the low NOx gas burners recycled in combustion gas and the method for reducing discharge |
-
1981
- 1981-05-27 CA CA000378443A patent/CA1197143A/en not_active Expired
- 1981-06-03 MX MX18762781A patent/MX153659A/en unknown
- 1981-06-04 AU AU71327/81A patent/AU545781B2/en not_active Expired
- 1981-06-04 ES ES502789A patent/ES502789A0/en active Granted
- 1981-06-04 GB GB8117154A patent/GB2079925B/en not_active Expired
-
1984
- 1984-07-27 GB GB08419227A patent/GB2146112B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2146112B (en) | 1985-09-25 |
| AU7132781A (en) | 1981-12-10 |
| GB2079925B (en) | 1985-02-06 |
| AU545781B2 (en) | 1985-08-01 |
| ES8300192A1 (en) | 1982-10-01 |
| GB8419227D0 (en) | 1984-08-30 |
| GB2146112A (en) | 1985-04-11 |
| ES502789A0 (en) | 1982-10-01 |
| MX153659A (en) | 1986-12-16 |
| GB2079925A (en) | 1982-01-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4348170A (en) | Dual register, split stream burner assembly with divider cone | |
| US5408943A (en) | Split stream burner assembly | |
| US4400151A (en) | Controlled flow, split stream burner assembly | |
| US5011400A (en) | Controlled flow split steam burner assembly with sorbent injection | |
| JPH018803Y2 (en) | ||
| JPS6130163B2 (en) | ||
| US3145670A (en) | Burner | |
| CA1218265A (en) | Combustion system and method for a coal-fired furnace utilizing a wide turn-down burner | |
| US4471703A (en) | Combustion system and method for a coal-fired furnace utilizing a louvered low load separator-nozzle assembly and a separate high load nozzle | |
| US5192204A (en) | Dual atomizing multifuel burner | |
| US6145450A (en) | Burner assembly with air stabilizer vane | |
| RU2754480C1 (en) | Solid-fuel heater with three-zone combustion air supply | |
| EP0163423B1 (en) | Controlled flow, split stream burner assembly with sorbent injection | |
| CA1197143A (en) | Dual register, split stream burner assembly | |
| KR830000916B1 (en) | Control of air flow in a burner for a tangentially fired boiler | |
| JPH0159481B2 (en) | ||
| US4201539A (en) | Flame forming burner | |
| US2982347A (en) | Fuel burning method and apparatus | |
| US2793686A (en) | Axially adjustable fuel burner for furnaces | |
| GB1585410A (en) | Burner | |
| CA1204342A (en) | Dual register, split stream burner assembly | |
| RU2083921C1 (en) | Rotary burner for liquid fuel | |
| US3186382A (en) | Turbulent smelting chamber with air supply collars | |
| US2512196A (en) | Air vane for fuel burners | |
| RU2406927C1 (en) | Steam boiler with twin swirling-type furnace |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |