CA1204342A - Dual register, split stream burner assembly - Google Patents

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.

Description

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This application is a division of Canadian Serial No.
378,443, filed May 27, 1981.
BACKGROUND OF THE INVENTION
This invention relates generally to a burner assembly and more particularly to an improved burner assembly which operates in a manner to reduce the formation of nitrogen oxides as a result of fuel combustion.
Considerable attention and efforts have recently been directed to the reduction of nitrogen oxides resulting from the combustion of fuel, and especially in connection with the use of coal in the furnace sections of relatively large installations such as vapor generators and the like. In a typical arrangement for burning coal in a vapor generator, several burners are dis-posed in communication with the interior of the furnace and op-erate to burn a mixture of air and pulverized coal. The burners used in these arrangements are generally of the type in which a fuel air mixture is continuously injected through a nozzle so as to form a single relatively large flame. As a result, the surface area of the flame is relatively small in comparison to its volume, and therefore the average flame temperature is rel-atively high. However, in the burning of coal, nitrogen oxides are formed by the fixation of atmospheric nitrogen available in the combustion supporting air, which is a function of the flame temperature. When the flame temperature exceeds 2800F, the amount of fixed nitrogen removed from the combustion supporting air rises exponentially with increases in the temperature. This condition leads to the production of high levels of nitrogen oxides in the final combustion products, which causes severe air pollution problems.
Nitrogen oxides are also formed from the fuel bound nitrogen available in the fuel itself, which is not a direct function of the flame temperature, but is related to the quantity of available oxygen during the combustion process.

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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 com-bustion, flue gas recirculation, the introduction of an oxygen-deficient fuel-air mixture to the burner and the breaking up of a single large flame 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 invention to which this divisional application is directed pertains to a burner assembly which operates in a manner to considerably reduce the production of nitrogen oxides in the combustion of fuel without any significant increase in cost or other related problems.
The invention in this divisional application in one aspect pertains to a burner assembly comprising means defining an annular passage with an inlet located at one end of the passage for receiving fuel and an outlet located at the other end of the passage for discharging the fuel. A divider member is dlsposed within the annular passage for dividing the stream of fuel passing through the passage into two radially-spaced parallel streams. Means are provided for splitting up one of the streams as it discharges from the opening so that, upon ignition of the fuel, a plurality of flame patterns are formed.

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The invention in this divisional application also comprehends a burner assembly of the type above including a register assembly associated with the burner, the register assembly comprising an enclosure extending over the passage for receiving air, and means for directing the air from the enclosure towards the outlet in two parallel paths extending around the passage. A plurality o vanes are respectively disposed in each of the paths for regulating the spin and/or quantity of air flowing through the paths.
The invention still further 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.
Inlet means is located at one end of the passage for directing a fuel stream mixture of pulverized coal and air into the passage in a tangential relation relative to the passage. An outlet is located at the other end of the passage for discharging the fuel stream. Means are disposed with the annular passage for dividing the stream of fuel pass-ing through the passage into two radially spaced parallel streams. A substantial portion of the coal flows into the outer of the spaced parallel streams by centrifugal forces, means regulate the flow rate of at least one of the streams, and an air inlet opening is formed in a portion of the outer tubular member for admitting air to the outer stream as the outer stream discharges from the outlet.

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BRIEF DESCRIPTION OF THE 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 front elevational view of the nozzle of Fig. 6; and Fig. 8 is a longitudinal cross-sectional view of the nozzle of Fig. 6.

DESCRIPTION OF THE_PREFERRED EMBODIMENTS
Referring in general to the embodiment of Figs. 1-4 of the drawings and specifically to Fig. 1, the reference numeral 10 refers in general to a burner assembly which is disposed in axial alignment with a through opening 12 formed in a front wall 14 of a conventional furnace. 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 for acco~modating additional burner assemblies identical to the burner assembly lZ0434Z
10. The inner surface of the wall 14 as well as the other walls of the furnace are lined within an appropriate thermal insulation material 18 and, while not specifically shown, it is understood that the combustion chamber 16 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 producin~ 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, bottom 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 10 includes a nozzle 20 having an inner tubular member 22 and an outer tubular member 24. The outer tubular member 24 extends over the inner tubular member 22 in a coaxial, spaced relationship thereto to define an annular passage 26 which extends towards the furnace opening 12.
A tangentially disposed inlet 28 communicates with the outer tubular member 24 for introducing a stream of fuel into the annular passage 26 as will be explained in further detail later.
A pair of spaced annular plates 30 and 32 extend around the burner 20, with the inner edge of the plate 30 terminating on the outer tubular member 24. A liner member 34 extends from the inner edge of the plate 32 and in a general longitudinal direction relative to the burner 20 and terminates adjacent the insulation material 18 just inside the wall 14. An additional annular plate 38 extends around the burner 20 in a spaced, parallel relation with the plate 30. An air divider sleeve 40 extends from the inner surface of the plate 38 and between the liner 34 and the nozzle 20 in a su~stantially parallel relation to the burner 20 and the liner 34 to define two air flow passages 42 and 44.
A plurality of outer register vanes 46 are pivotally mounted between the plates 30 and 32 to control the swirl of secondary air from the wind box to the air flow passages 42 and 44. In a similar manner a plurality of inner register vanes 48 are pivotally mounted between the plates 30 and 38 to further regulate the swirl of the secondary air passing through the annular passage 44. It is understood that although only two register vanes 46 and 48 are shown in Fig.
1, several more vanes extend in a circumferentially spaced relation to the vanes shown. Also, the pivotal mounting of the register vanes 46 and 48 may be done in any conventional manner, such as by mounting the vanes on shafts (shown schematically in Fig. 1) and journalling the shafts in proper bearings formed in the plates 30, 32 and 38. Also, the position of the vanes 46 and 48 may 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.
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 bur-ner nozzle 20. An elongated worm gear 52 is provided for mov-ing the sleeve 50 and is better shown in Fig. 2. The worm gear 52 has one end portion suitably connected to an appropriate drive means (not shown) for rotating the worm gear and the other end provided with threads 52a. The worm gear 52 extends through a bushing 54 (Fig. 1) which is attached to the plate 30 to provide rotatable support. The threads 52a of the worm gear 52 12043~Z
mesh with appropriate apertures 56 formed in the sleeve 50 so that, upon rotation of the worm gear, the sleeve moves long-itudinally with respect to the longitudinal axis of the burner 20 and across the air inlet defined by the plates 30 and 32.
In this manner, the quantity of combustion 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 plates 30 and 32 immediately downstream of the sleeve 50 to permit the air flow to the burner 20 to be independently determined by means of static pressure differential movements, in a conventional manner.
As shown in Fig. 3, which depicts the details of the burner nozzle 20, the end portion of the outer tubular member 24 and the corresponding end portion of the inner tubular member 22 are tapered slightly radially inwardly toward the furnace opening 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 Fig. 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 corresponding curved surfaces of the tubular members 22 and 24 and the blocks are tapered radially inwardly. As shown in Figure 4, the leading end portion of each block 60 is configured in a curved relationship so that the fuel flowing in the passage 26 and impinging against the leading ends of the blocks 60 will be directed into the adjacent spaces defined between the blocks to facilitate the splitting of the fuel stream into four separate streams.

In operation of the burner assembly of the present invention, the movable sleeve 50 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 50 are needed since normal control of the secondary air to the burners is accomplished by operation of the outer register vanes 46.
Fuel preferably in the form of pulverized coal suspended or entrained within a source of primary air, is introduced into the tangential inlet 28 where it swirls through the annular chamber 26 and is ignited by suitable igniters (not shown) appropriately positioned with respect to the burner nozzle 20.
The stream of fuel and air encounters the blocks 60 at the end portion of the nozzle 20 whereby the stream is split into four equally spaced streams which, upon ignition, form four separate flame patterns. The igniters are shut off after steady 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 and 32. The axial and radial velocities of the air is controlled by the register vanes 46 and 48 as it passes through the air flow passages 42 and 44 and into the furnace opening 12 for mixing with the fuel from the burner 20.
As a result of the foregoing, several advantages result from the burner assembly of the present invention. For example, since the pressure drop across the perforated air hoods 58 asso-ciated with burner assemblies can be equalized by balancing ~2~)434Z

the secondary air flow to each burner by initially adjusting the sleeves 50, a substantially uni~orm qas distribution can be obtained across the furnace. ~h~s also permits a common wind box to be used and enables the un~t to operate at lower excess air with significant reduction~ ~n both nltrogen oxides and carbon monoxides. Also, the provision of separate register vanes 46 and 48 for the outer and inner air flow passages 42 and 44 enablès ~econdary air distribution as well as flame shape to be independently controlled resulting in a significant reduction of nitrogen oxides, and a more gradual mixing o~ the primary air coal stream with the secondary air since both streamq enter the furnace on parallel paths with controlled mixing.
Further, the provision of multiple flame patterns results in a greater ~lame radiation, a lower average flame temperature and a shorter residen~e time of the gas com-ponents within the flame at a maximum temperature, all of which, as stated above, contribute to reduce the formation of nitric oxides.
Also, the use of the curved surface 60a on the blocks results in a more streamline flow of the fuel stream before it discharges from the outlet of the nozzle 20. Still further, the provision of the tangential inlet 26 provides excellent distribution of the fuel around the annular space 26 in the burner 20 resulting in more complete c~mbustion and reduction of carbon loss and ma~ing it possible to use individual burners with capacities significantly higher than otherwise could be used.

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An alternative embodiment of the present invention is depicted'in Fig~. 5-8. Referring specifically to Fig. S the reference numeral 110 refers in general to a burner assembly which is disposed in axial alignment with ~ through 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 configur~tion to define a combustion chamber 116 immediately adjacent the opening 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 speci~ically shown, it is understood that the combustion chamber 116 can also be lined with boiler tubes through which a heat exchange fluid, such as water is circulated in a conventional m2nner for the purposes of producing steam.
It is also understood that a vertical wall is disposed in a parallel relationship with the ~urnace wall 14 along with connecting top, bottom, and side walls to form a plenum chamber, or wind box, for receiving combustion supporting air, commonly referred to as "secondary air", in a convention~l manner.
The burner assembly 110 includes a nozzle 120 having an inner tubular me~'oer 122 and an outer tubular member 124.
The outer tubular member 124 extends over the inner tubular member 122 in a coaxial, 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 mer~er 124 for .ntroducing ~2~434Z

a stream of fuel and air into the annu}ar passage 126 as will be explained in further detail later.
A pair of spaced annular plates 1 0 and 132 extend around the nozzle 120, with the inner edge of the plate 130 terminating on the outer tubular member 124. A liner member 134 extends from the innex edge of the plate 132 and in a general longitudinal direction relative to the nozzle 120 and terminates adjacent the ~nsulation material 118 ~ust inside the wall 114. An additional annular plate 138 extends around the nozzle 120 in a spaced, parallel relation with the plate 130. An air divider sleeve 140 extends 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 of outer register vanes 146 are pivotally mounted between the plates 130 and 132 to control the swirl of secondary air ~xom 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 148 are shown in Fig. 5, several more vanes extend in a circum-ferentially spaced relation to the vanes shown. Also, the pivotal mounting of the vanes 146 and 148 may be done in any conventional manner, such as by mounting the vanes on shafts (shown schematically) and journallir.g the shafts in proper bearings formed in the plates 130, 132 and 138. Also, the position of the vanes 146 and 148 mav be adjustable by means lZ04342 of cranks or the like. Since these types of components are conventional they are not shown in the drawings nor will be descxibed in any further detail.
It is understood that the quantlty o~ 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 periphery of the plate 132 and is movable parallel to the longitudinal axis of the nozzle 120. This movement can be achieved by using an elongated worm gear and associated apparatus in a manner identical to that disclosed in the prevlous embodi-ment. Thus, the quantity o~ 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 immediately downstream of the sleeve 150 to permit determination of the secondary air flow to the burner as 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 corresponding end portion of the inner tubular member 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 portions of inner tubular member 122 and the outer tubular 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.

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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 i~ the outlet end portion of the nozzle 120. As shown in Figs. 6 and 7, four such splitters 160 are spaced at 90 ~ntervals and extend from the outlet to a point approximately midway between the tapered portions of the tubular members 122 and 124. Each splitter 160 is formed by two plate members welded together at their ends to form a V-shape. The plate members are also welded along their respective longitudinal edyes to the outer tubular member 1~4 and the divider cone 158 to support the splitters and the divider cone in the nozzle 120. The apex of each splitter 160 is disposed upstream of the nozzle outlet so that the fuel-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 member 124 and respectively extend immediately over the splitters 160. These openings are for the purpose of admi;tting secondary air from the inner air flow passage 144 (Fig. 1) into the annular space defined between the divider cone 158 and the outer tubular member 124 for reisons 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 plurality of rods 166 extending within the tubular member and affixed 12q:~4342 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 hydraulic cylinder or the like to effect longitudinal movement of the rods and therefore the tip 164 in a conventional mænner.
It can be appreciated from a ~iew of Fig. 8 that the longitudinal movement of the tip 164 varies the effective 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 movemen~ 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 noz~le 120 for igniting the coal as it discharges from the nozzle. 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 burners is accomplished by operation of the outer burner vanes 146. However, if desired, flow control can be accomplished by the sleeve.

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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 it swirls through the annular chamber 126. Since the pulverized coal introduced into the inlet 128 is heavier than the air, the pulverized coal will tend to move radi~lly outwardly towards the inner wall of the outer tubular member 124 under the centrifugal forces thus produced. ~s a result, a great ma~ority o~ the coal along with a relatively small port~on of air enters the outer annular passage aefined between the outer tubular member 124 and the divider cone 158 (Fig. 8) where it encounters the apexes of the splitters 160. The stream is thus split into four equally spaced streams which discharge from the nozzle outlet and, upon ign~tion, form four separate ~lame patterns. Secondary air from the inner air passage 14~ (Pig. 5) passes through the $nlets 162 formed in the outer tubular member 124 and enters the annular passage between the latter member and the d~vider 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 enters the annular passage defined between the divider cone 158 and the 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 adjusted to precisely control the relative amount, and therefore velocity, of the air and coal discharging from the nozzle 120 from the annular passages between the outer 1~043~2 tubular member 124 and the divider cone 158 and ~etween the divider cone and the inner ~ubular member 122.
Secondary air from the wlnd box is admitted through the perforated hood 156 and into the inlQt 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 2nd 144 and into the furnace opening 112 for mixing with the coal from the nozzle 120. The igniters are then shut off after steady state com-bustion has been achieved.
As a result of the foregoing, several advantages resultfrom the burner assembly of the 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 the sleeves 150, a substantially uniform 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 provision of 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 independe~tly 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 ~434Z

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 maxLmum temperature, all of which, as stated abovel contribute to reduce the formation of nitric oxides.
Still further, the provision of the tangential inlet 126 pro~ides excellent d$stribution o~ the fuel around the annular space 126 in the nozzle 120, resulting in more complete co~bustion and reduct~ on o~ carbon loss and making it possible to use individual burners with capacitie~
significantly higher than otherwise could be used. Pro-vision o~ the inlet openings 162 in the outer tubular member permits the introduction of a portion of the secondary air to be entrained with the fuel-air stream passing through the annular passage between the outer tubular member 124 and the divider cone, since the majori~y of this stream will be primarily pulverized coal. As a result, a substantially uniform air-coal ratio across the entire cross-section of the air-coal stream is achieved. .Also, the provision of the movable tip 164 to regulate the flow of the coal-air mixture passing through the inner annular passage defined between the divider cone 158 and the inner tubular member 122 enables the air flow on both sides o~ 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 embodiments of the prevent invention within the scope of the invention. For example, since the arrangement of the present invention permits the admission 1~043~Z

of air at less than stoichiometric, overfire air ports, or the like can be provided as needed to supply air to complete the combustion.
As will be apparent to those skilled in the art, other changes and modifications may be made to the embodiments of the present invention without departing from the spirt and scope of the present invention as defined in the appended claims and the legal equi~alent.

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Claims (27)

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:

1. A burner assembly comprising means defining an annular passage, an inlet located at one end of said 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 dividing the stream of fuel passing through said passage into two parallel streams, means for splitting up one of said streams as it discharges 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 passage for receiving air, and means for directing said air from said enclosure towards said outlet in two parallel paths extend-ing around said passage, and a plurality of vanes respectively disposed in each of said paths for regulating the spin and/or 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 coaxial relation thereto.

3. The burner assembly of Claim 2 wherein said stream dividing means comprises a tubular divider member disposed in said passage to divide said stream into an inner stream, and an outer stream extending around said inner stream.

4. The burner assembly of Claim 3 wherein said splitting means extends between said outer tubular member and said divider member.

5. The burner assembly of Claim 1 wherein said splitting means comprises a plurality of V-shaped members extending in circumferentially spaced relationship in said passage and disposed in said passage so that the apex of each member faces upstream and said one stream impinges against said members which direct said stream into the spaces between said members.

6. The burner assembly of Claim 3 further comprising an air inlet opening formed in a portion of said outer tubular member extending over said splitting means for admitting air from one of said paths to said outer stream.

7. The burner assembly of Claim 1, further comprising means for regulating the flow rate of at least one of said streams.

8. The burner assembly of Claim 7 wherein said flow rate regulating means comprises a movable tip disposed on the end of said inner tubular member and movable relative to said inner tubular member.

9. The burner assembly of Claim 1 further comprising means for directing fuel through said inlet and into said passage in a tangential direction relative to said passage.

10. The burner assembly of Claim 1 further comprising a sleeve movable across the inlet to said enclosure to vary the size of said inlet and regulate the quantity of air entering said enclosure.

11. A burner assembly comprising means defining an annular passage, an inlet located at one end of said passage for receiving fuel, and an outlet located at the other end of said passage for discharging said fuel;
a divider member disposed within said annular passage for dividing the stream of fuel passing through said passage into two radially-spaced parallel streams, and means for splitting up one of said streams as it discharges from said opening so that, upon ignition of said fuel, a plurality of flame patterns are formed.

12. The burner assembly of Claim 11 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, said divider member extending between said inner tubular member and said outer tubular member.

13. The burner assembly of Claim 12 wherein said splitting means extends between said outer tubular member and said divider member in the path of said outer stream.

14. The burner assembly of Claim 13 further comprising an air inlet opening formed in a portion of said outer tubular member extending over said splitting means for admitting air to said outer stream.

15. The burner assembly of Claim 11 wherein said splitting means comprises a plurality of V-shaped members extending in a circumferentially spaced relationship in said passage and disposed in said passage so that the apex of each member faces upstream and said one stream impinges against said members which direct said stream into the spaces between said members.

16. The burner assembly of Claim 11 further comprising means for regulating the flow rate of at least one of said streams.

17. The burner assembly of Claim 16 wherein said flow rate regulating means comprises a movable tip disposed on the end of said inner tubular member and movable relative to said inner tubular member.

18. The burner assembly of Claim 11 further comprising means for directing fuel through said inlet and into said passage in a tangential direction relative to said passage.

19. The burner assembly of Claim 11 further comprising a register assembly associated with said burner, said register assembly comprising an enclosure extending over said passage for receiving air, means for directing said air from said enclosure towards said outlet, and a sleeve movable across the inlet to said enclosure to vary the size of said inlet and regulate the quantity of air entering said enclosure.

20. A burner assembly comprising an inner tubular member, and an outer tubular member extending around said inner tubular member in a coaxial relation thereto to define an annular passage, inlet means located at one end of said passage for directing a fuel stream mixture of pulverized coal and air into said passage in a tangential relation relative to said passage, an outlet located at the other end of said passage for discharging said fuel stream; means disposed with said annular passage for dividing the stream of fuel passing through said passage into two radially spaced parallel streams, a substantial portion of said coal flowing into the outer of said spaced parallel streams by centrifugal forces, means for regulating the flow rate of at least one of said streams, and an air inlet opening formed in a portion of said outer tubular member for admitting air to said outer stream as said outer stream discharges from said outlet.

21. The burner assembly of Claim 20 wherein said stream dividing means comprises a tubular divider member disposed in said passage between said inner tubular member and said outer tubular member.

22. The burner assembly of Claim 21 further comprising means for splitting up one of said streams as it discharges from said opening so that upon ignition of said coal, a plurality of flame patterns are formed.

23. The burner assembly of Claim 22 wherein said splitting means extends between said outer tubular member and said divider member and splits up said outer stream.

24. The burner assembly of Claim 22 wherein said splitting means comprises a plurality of V-shaped members extending in a circumferentially spaced relationship in the annular space between said outer tubular member and said divider member and disposed in said passage so that the apex of each member faces upstream and said outer stream flows against said members which direct said stream into the spaces between said members.

25. The burner assembly of Claim 20 further comprising a register assembly associated with said burner, said register assembly comprising an enclosure extending over said passage for receiving air, means for directing said air from said enclosure towards said outlet, and a sleeve movable across the inlet to said enclosure to vary the size of said inlet and regulate the quantity of air entering said enclosure.

26. The burner assembly of Claim 20 further comprising means for regulating the flow rate of at least one of said streams.

27. The burner assembly of Claim 26 wherein said flow rate regulating means comprises a movable tip disposed on the end of said inner tubular member and movable relative to said inner tubular member.