EP0163423B1 - Controlled flow, split stream burner assembly with sorbent injection - Google Patents
Controlled flow, split stream burner assembly with sorbent injection Download PDFInfo
- Publication number
- EP0163423B1 EP0163423B1 EP19850302979 EP85302979A EP0163423B1 EP 0163423 B1 EP0163423 B1 EP 0163423B1 EP 19850302979 EP19850302979 EP 19850302979 EP 85302979 A EP85302979 A EP 85302979A EP 0163423 B1 EP0163423 B1 EP 0163423B1
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- EP
- European Patent Office
- Prior art keywords
- air
- burner assembly
- tubular member
- fuel
- passage
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J7/00—Arrangement of devices for supplying chemicals to fire
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- 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
Definitions
- 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 and sulfur dioxides as a result of fuel combustion.
- burners In a typical arrangement for burning coal in a vapor generator, several burners are disposed in communication with the interior of the furnace and operate 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.
- Control of sulfur dioxide emissions is usually achieved by external means such as wet or dry flue gas desulfurization.
- In-situ control i.e., within the furnace
- In-situ control has been under investigation for many years and utilizes either a pre-mixing of limestone (or other sorbent) with coal, or an injection of pulverized sorbent external to the burner throat through separate ports or small injection nozzles, as may be seen, for example, in the GB-A-2,056,656.
- both of these techniques have distinct drawbacks.
- the injection of the sorbent with the coal usually yields low sulfur dioxide capture ratios due to deabburning of the sorbent and can lead to increased slagging.
- the external injection of the sorbent requires numerous wall penetrations, tube bends and expensive piping and burner staging controls for the ports.
- sorbent injection between or above the burners can limit sulfur capture due to several effects:
- An internally-stage low NO, burner can be defined as one which yields fuel-rich and fuel- lean zones within a flame envelope similar to that of a turbulent burner. This is in contrast to delayed mixing burners which produce very long narrow flames which gradually combust the fuel over a substantially greater distance than is characteristic of either turbulent or internally staged burners.
- a burner assembly comprising means defining an annular fuel passage consisting of an inner tubular member and an outer tubular member extending around said inner tubular member in a coaxial relation thereto, an inlet located at one end of said passage for receiving fuel and adapted to direct such fuel tangentially thereinto, and a nozzle located at the other end of said passage for discharging said fuel, an enclosure extending over said fuel passage for receiving air, and means for directing said air from said enclosure towards said nozzle in two radially spaced, parallel paths extending around said passage.
- Deflector blocks positioned between the inner and outer tubular members within the nozzle region circumferentially divide the flow and cause a flame pattern to form during combustion.
- a better control of the flame pattern and greater sulfur reduction is, however, obtained by means of the present arrangement, disclosed herein, which is characterised in comprising a sleeve disposed within said passage for dividing the stream into two radially spaced parallel annular streams such that a substantial portion of said particulate fuel flows into the said outer annular stream as a consequence of centrifugal forces, means for regulating the flow rate in at least one of said parallel annular streams, at least one air inlet opening formed in a portion of said outer tubular member for admitting air to said outer annular stream as it discharges from said nozzle, and means for injecting sorbent into the radially outer path at said nozzle for capturing the sulfur produced as a result of combustion of said fuel.
- 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 accommodating additional burner assemblies identical to the burner assembly 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 boiler tubes through which a heat exchange fluid, such as water, is circulated in a conventional manner for the purposes of producing steam.
- 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 substantially 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.
- 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.
- 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 journaling the shafts in proper bearings formed in the plates 30, 32 and 38.
- 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.
- a plurality of sorbent injectors 49 are provided, each of which extends through the plates 30 and 38, between two vanes 48 and into the air flow passage 42.
- the inlet end portion (not shown) of each injector 49 is connected to a source or sorbent such as limestone, Ca(OH)2, or the like and the discharge end is located at the opening 12 of the front wall 14.
- a source or sorbent such as limestone, Ca(OH)2, or the like
- the discharge end is located at the opening 12 of the front wall 14.
- 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 nozzle 20.
- An elongated worm gear 52 is provided for moving the sleeve 50 and is better shown in Figure 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 mesh with appropriate apertures 55 formed in the sleeve 50 so that, upon rotation of the worm gear, the sleeve moves longitudinally 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 air flow passages 42 and 44 can be controlled by axial displacement of the sleeve 50.
- a perforated air hood 56 extends between the plates 30 and 32 immediately downstream of the sleeve 50 to permit independent measurement of the air flow to the burner 20.
- FIGs. 3-5 which depict the details of the 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 divider cone 58 extends between the inner tubular member 22 and the outer tubular member 24.
- the divider cone 58 has a straight portion 58a (Fig. 5) which extends between the straight portions of inner tubular member 22 and the outer tubular member 24, and a tapered portion 58b which extends between the tapered portions of the tubular members for the entire lengths thereof.
- the function of the divider cone 58 will be described in greater detail later.
- a plurality of V-shaped splitters 60 are circumferentially spaced in the annular space between the outer tubular member 24 and the divider cone 58 in the outlet end portion of the nozzle 20. As shown in Figs. 3 and 4, four such splitters 60 are spaced at 90° intervals and extend from the outlet to a point approximately midway between the tapered portions of the tubular members 22 and 24.
- Each splitter 60 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 edges to the outer tubular member 24 and the divider cone 58 to support the splitters and the divider cone in the nozzle 20.
- each splitter 60 is disposed upstream of the nozzle outlet so that the fuel-air stream flowing in the annular space between the divider cone 58 and the outer tubular member 24 will be directed into the adjacent spaces defined between the splitters to facilitate the splitting of the fuel stream into four separate streams.
- pie-shaped openings 62 are formed through the outer tubular member 24 and respectively extend immediately over the splitters 60. These openings are for the purpose of admitting secondary air from the inner air flow passage 44 (Fig. 1) into the annular space defined between the divider cone 58 and the outertubular member 24 for reasons that will be explained in detail later.
- a tip 64 is formed on the end of the tapered portion of the inner tubular member 22 and is movable relative to the latter member by means of a plurality of rods 66 extending within the tubular member and affixed to the inner wall of the tip.
- the other ends of the rods 66 can be connected to any type of actuator device (not shown) such as a hydraulic cylinder of the like to effect longitudinal movement of the rods and therefore the tip 64 in a conventional manner.
- the longitudinal movement of the tip 64 varies the effective outlet opening defined between the tip and the divider cone 58 so that the amount of fuel-air flowing through this opening can be regulated. Since the divider cone 58 divides the fuel-air mixture flowing through the annular passage 26 into two radially spaced parallel streams extending to either side of the divider cone 58, it can be appreciated that movement of the tip 64 regulates the relative flow of the two streams while varying their velocity.
- ignitors can be provided adjacent the outlet of the nozzle 20 for igniting the coal as it discharges from the nozzle. Since these ignitors are of a conventional design they have not been shown in the drawings in the interest of clarity.
- 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 flow to the burners is accomplished by operation of the outer burner vanes 46. 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 28 where it swirls through the annular chamber 26. Since the pulverized coal introduced into the inlet 28 is heavier than the air, the pulverized coal will tend to move radially outwardly towards the inner wall of the outer tubular member 24 under the centrifugal forces thus produced. As a result, a great majority of the coal along with a relatively small portion of air enters the outer annular passage defined between the outer tubular member 24 and the divider cone 58 (Fig. 5) where it encounters the apexes of the splitters 60.
- the stream is thus split into four equally spaced streams which discharge from the nozzle outlet and, upon ignition, form four separate flame patterns.
- Secondary air from the inner air passage 44 (Fig. 1) passes through the inlets 62 formed in the outer tubular member 24 and enters the annular passage between the latter member and the divider cone 58 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 26 enters the annular passage defined between the divider cone 58 and the inner tubular member 22.
- 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 64 can be adjusted to precisely control the relative amount, and therefore velocity, of the air and coal discharging from the nozzle 20 from the annular passages between the outer tubular member 24 and the divider cone 58 and between the divider cone and the inner tubular member 22.
- Sorbent is injected, by the injectors 49, into the secondary air stream flowing through the flow passage 42 at the opening 12 to capture the sulfur dioxide produced as a result of combustion of the coal.
- 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 components within the flame at a maximum temperature, all of which, as stated above, contribute to reduce the formation of nitric oxides.
- the provision of the tangential inlet 28 provides excellent distribution of the fuel around the annular space 26 in the nozzle 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.
- Provision of the inlet openings 62 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 24 and the divider cone, since the majority 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.
- the provision of the movable tip 64 to regulate the flow of the coal-air mixture passing through the inner annular passage defined between the divider cone 58 and the inner tubular member 22 enable the airflow on both sides of the divider cone to be regulated thereby optimizing the primary air velocity with respect to the secondary air velocity.
- the particles will by-pass the hottest part of the flame so that a minimum of deadburning of the sorbent will occur. Also, since the sorbent particles will be rapidly entrained in the swirling secondary air from this outer secondary annulus they will be intimately mixed with the products of combustion as soon after passing the peak flame temperature zone as is feasible. This increases the efficiency of the sulfur capture and results in capture that is equal to or betterthan capture methods external to the burner throat.
- the arrangement permits the admission of air at less than stoichiometric for further reductions in NO,, emissions, overfire air ports, orthe like can be provided as needed to supply air to complete the combustion.
- the distribution of the sorbent injectors 49 around the periphery of the burner can be varied to obtain optimum sulfur capture.
- the burner levels which receive sorbent injectors are dependent on the number of burner levels, slagging characteristics of the coal ash and the gas temperature at the exit to the furnace's radiant zone. Boilers with three or more burner levels need only have the top two levels contain sorbent injectors. This is sufficient to provide an effective calcination zone for calcium- based sorbents along with a long residence time for sulfation reactions to occur prior to the furnace exit.
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Description
- 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 and sulfur dioxides as a result of fuel combustion.
- In a typical arrangement for burning coal in a vapor generator, several burners are disposed in communication with the interior of the furnace and operate 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.
- In the burning of coal in this manner, unacceptable levels of sulfur dioxide are produced which must be reduced in order to meet government standards of air quality. Also, when the flame temperature at the burner exceeds 1538°C (2800°F), 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 also causes severe air pollution problems.
- Control of sulfur dioxide emissions is usually achieved by external means such as wet or dry flue gas desulfurization. In-situ control (i.e., within the furnace) has been under investigation for many years and utilizes either a pre-mixing of limestone (or other sorbent) with coal, or an injection of pulverized sorbent external to the burner throat through separate ports or small injection nozzles, as may be seen, for example, in the GB-A-2,056,656. However, both of these techniques have distinct drawbacks. The injection of the sorbent with the coal usually yields low sulfur dioxide capture ratios due to deabburning of the sorbent and can lead to increased slagging. The external injection of the sorbent requires numerous wall penetrations, tube bends and expensive piping and burner staging controls for the ports.
- Also, sorbent injection between or above the burners can limit sulfur capture due to several effects:
- -Inadequate mixing between the products of combustion and the sorbent particles;
- -Insufficient residence time in the boiler's radiant zone; and
- -Increased slagging and sorbent deposition to the boiler's sidewalls when sorbent is injected to the lower burner levels of a multiple level boiler. This injection location also reduces sulfur capture since sorbent particles can be re-entrained in the high temperature portion of the flame.
- These deficiencies can be corrected by injecting sorbent in conjunction with an internally staged low NOX burner. This type of burner reduces NOx by at least 50%, as compared to turbulent burners, without simultaneous use of external combustion air staging systems such as overfire or tertiary air ports. However, when overfire air ports are used, NO, reductions as great as 75% can be obtained. An internally-stage low NO,, burner can be defined as one which yields fuel-rich and fuel- lean zones within a flame envelope similar to that of a turbulent burner. This is in contrast to delayed mixing burners which produce very long narrow flames which gradually combust the fuel over a substantially greater distance than is characteristic of either turbulent or internally staged burners.
- Other attempts, including two-stage combustion, flue gas recirculation and the introduction of an oxygen-deficient fuel-air mixture suppress the flame temperature and reduce the quantity of available oxygen during the combustion process and thus reduce the formation of nitrogen oxides. 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, nor do they lend themselves to sulfur control via sorbent injection.
- In our US A4,400,151 a burner assembly is described comprising means defining an annular fuel passage consisting of an inner tubular member and an outer tubular member extending around said inner tubular member in a coaxial relation thereto, an inlet located at one end of said passage for receiving fuel and adapted to direct such fuel tangentially thereinto, and a nozzle located at the other end of said passage for discharging said fuel, an enclosure extending over said fuel passage for receiving air, and means for directing said air from said enclosure towards said nozzle in two radially spaced, parallel paths extending around said passage. Deflector blocks positioned between the inner and outer tubular members within the nozzle region circumferentially divide the flow and cause a flame pattern to form during combustion. A better control of the flame pattern and greater sulfur reduction is, however, obtained by means of the present arrangement, disclosed herein, which is characterised in comprising a sleeve disposed within said passage for dividing the stream into two radially spaced parallel annular streams such that a substantial portion of said particulate fuel flows into the said outer annular stream as a consequence of centrifugal forces, means for regulating the flow rate in at least one of said parallel annular streams, at least one air inlet opening formed in a portion of said outer tubular member for admitting air to said outer annular stream as it discharges from said nozzle, and means for injecting sorbent into the radially outer path at said nozzle for capturing the sulfur produced as a result of combustion of said fuel.
- The above brief description of the features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein:
- 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. 1;
- Fig. 3 is an enlarged elevational view, partially cut-away, of the burner portion of the assembly of the present invention;
- Fig. 4 is an end view of the burner portion of Fig. 3; and
- Fig. 5 is a cross-sectional view taken along the line 5-5 of Fig. 3.
- Referring specifically to Figure 1 of the drawings the
reference numeral 10 refers in general to a burner assembly which is disposed in axial alignment with a throughopening 12 formed in afront 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 acombustion chamber 16 immediately adjacent theopening 12. Also similar openings are provided in the furnacefront wall 14 for accommodating additional burner assemblies identical to theburner assembly 10. The inner surface of thewall 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 thecombustion chamber 16 can also be lined with 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, 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 anozzle 20 having an innertubular member 22 and an outertubular member 24. The outertubular member 24 extends over the innertubular member 22 in a coaxial, spaced relationship thereto to define anannular passage 26 which extends towards thefurnace opening 12. - A tangentially disposed
inlet 28 communicates with the outertubular member 24 for introducing a stream of fuel into theannular passage 26 as will be explained in further detail later. - A pair of spaced
annular plates burner 20, with the inner edge of theplate 30 terminating on the outertubular member 24. A liner member 34 extends from the inner edge of theplate 32 and in a general longitudinal direction relative to theburner 20 and terminates adjacent the insulation material 18 just inside thewall 14. An additional annular plate 38 extends around theburner 20 in a spaced, parallel relation with theplate 30. Anair divider sleeve 40 extends from the inner surface of the plate 38 and between the liner 34 and thenozzle 20 in a substantially parallel relation to theburner 20 and the liner 34 to define twoair flow passages - A plurality of
outer register vanes 46 are pivotally mounted between theplates air flow passages inner register vanes 48 are pivotally mounted between theplates 30 and 38 to further regulate the swirl of the secondary air passing through theannular passage 44. It is understood that although only tworegister vanes register vanes plates vanes - A plurality of
sorbent injectors 49 are provided, each of which extends through theplates 30 and 38, between twovanes 48 and into theair flow passage 42. The inlet end portion (not shown) of eachinjector 49 is connected to a source or sorbent such as limestone, Ca(OH)2, or the like and the discharge end is located at theopening 12 of thefront wall 14. Although not clear from the drawing, it is understood that more than twoinjectors 49 can be provided in a equilangularly spaced relation around thenozzle 20, and that the velocity of injection and injection angle can be controlled at each injector in a conventional manner. - The quantity of air flow from the wind box into ' the
register vanes 46 is controlled by movement of asleeve 50 which is slidably disposed on the outer periphery of theplate 32 and is movable parallel to the longitudinal axis of theburner nozzle 20. Anelongated worm gear 52 is provided for moving thesleeve 50 and is better shown in Figure 2. Theworm 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. Theworm gear 52 extends through a bushing 54 (Fig. 1) which is attached to theplate 30 to provide rotatable support. The threads 52a of theworm gear 52 mesh withappropriate apertures 55 formed in thesleeve 50 so that, upon rotation of the worm gear, the sleeve moves longitudinally with respect to the longitudinal axis of theburner 20 and across the air inlet defined by theplates air flow passages sleeve 50. Aperforated air hood 56 extends between theplates sleeve 50 to permit independent measurement of the air flow to theburner 20. - As shown in Figs. 3-5, which depict the details of the
nozzle 20, the end portion of the outertubular member 24 and the corresponding end portion of the innertubular member 22 are tapered slightly radially inwardly toward thefurnace opening 12. Adivider cone 58 extends between the innertubular member 22 and the outertubular member 24. Thedivider cone 58 has a straight portion 58a (Fig. 5) which extends between the straight portions of innertubular member 22 and the outertubular member 24, and atapered portion 58b which extends between the tapered portions of the tubular members for the entire lengths thereof. The function of thedivider cone 58 will be described in greater detail later. - A plurality of V-shaped
splitters 60 are circumferentially spaced in the annular space between the outertubular member 24 and thedivider cone 58 in the outlet end portion of thenozzle 20. As shown in Figs. 3 and 4, foursuch splitters 60 are spaced at 90° intervals and extend from the outlet to a point approximately midway between the tapered portions of thetubular members splitter 60 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 edges to the outertubular member 24 and thedivider cone 58 to support the splitters and the divider cone in thenozzle 20. The apex of eachsplitter 60 is disposed upstream of the nozzle outlet so that the fuel-air stream flowing in the annular space between thedivider cone 58 and the outertubular member 24 will be directed into the adjacent spaces defined between the splitters to facilitate the splitting of the fuel stream into four separate streams. - Four pie-shaped
openings 62 are formed through the outertubular member 24 and respectively extend immediately over thesplitters 60. These openings are for the purpose of admitting secondary air from the inner air flow passage 44 (Fig. 1) into the annular space defined between thedivider cone 58 and theoutertubular member 24 for reasons that will be explained in detail later. - As shown in Fig. 5, a
tip 64 is formed on the end of the tapered portion of theinner tubular member 22 and is movable relative to the latter member by means of a plurality ofrods 66 extending within the tubular member and affixed to the inner wall of the tip. The other ends of therods 66 can be connected to any type of actuator device (not shown) such as a hydraulic cylinder of the like to effect longitudinal movement of the rods and therefore thetip 64 in a conventional manner. - It can be appreciated from a view of Fig. 5 that the longitudinal movement of the
tip 64 varies the effective outlet opening defined between the tip and thedivider cone 58 so that the amount of fuel-air flowing through this opening can be regulated. Since thedivider cone 58 divides the fuel-air mixture flowing through theannular passage 26 into two radially spaced parallel streams extending to either side of thedivider cone 58, it can be appreciated that movement of thetip 64 regulates the relative flow of the two streams while varying their velocity. - It is understood that appropriate ignitors can be provided adjacent the outlet of the
nozzle 20 for igniting the coal as it discharges from the nozzle. Since these ignitors are of a conventional design they have not been shown in the drawings in the interest of clarity. - 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 thesleeves 50 are needed since normal control of the secondary air flow to the burners is accomplished by operation of the outer burner vanes 46. 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 28 where it swirls through theannular chamber 26. Since the pulverized coal introduced into theinlet 28 is heavier than the air, the pulverized coal will tend to move radially outwardly towards the inner wall of the outertubular member 24 under the centrifugal forces thus produced. As a result, a great majority of the coal along with a relatively small portion of air enters the outer annular passage defined between the outertubular member 24 and the divider cone 58 (Fig. 5) where it encounters the apexes of thesplitters 60. The stream is thus split into four equally spaced streams which discharge from the nozzle outlet and, upon ignition, form four separate flame patterns. Secondary air from the inner air passage 44 (Fig. 1) passes through theinlets 62 formed in the outertubular member 24 and enters the annular passage between the latter member and thedivider cone 58 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 26 enters the annular passage defined between thedivider cone 58 and theinner tubular member 22. The mixture entering this annular passage is mostly air due to the movement of the coal radially outwardly, as described above. The position of themovable tip 64 can be adjusted to precisely control the relative amount, and therefore velocity, of the air and coal discharging from thenozzle 20 from the annular passages between the outertubular member 24 and thedivider cone 58 and between the divider cone and theinner tubular member 22. - Secondary air from the wind box is admitted through the
perforated hood 56 and into the inlet between theplates register vanes air flow passages furnace opening 12 for mixing with the coal from thenozzle 20. The igniters are then shut off after steady state combustion has been achieved. - Sorbent is injected, by the
injectors 49, into the secondary air stream flowing through theflow passage 42 at theopening 12 to capture the sulfur dioxide produced as a result of combustion of the coal. - 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 56 associated with the burner assemblies can be equalized by balancing the secondary air flow to each burner by initially adjusting thesleeves 50, 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 ofseparate register vanes inner flow passages - 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 components within the flame at a maximum temperature, all of which, as stated above, contribute to reduce the formation of nitric oxides.
- Still further, the provision of the
tangential inlet 28 provides excellent distribution of the fuel around theannular space 26 in thenozzle 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. Provision of theinlet openings 62 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 outertubular member 24 and the divider cone, since the majority 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 themovable tip 64 to regulate the flow of the coal-air mixture passing through the inner annular passage defined between thedivider cone 58 and theinner tubular member 22 enable the airflow on both sides of the divider cone to be regulated thereby optimizing the primary air velocity with respect to the secondary air velocity. - Also, by injecting the sorbent into the outer secondary air annulus the particles will by-pass the hottest part of the flame so that a minimum of deadburning of the sorbent will occur. Also, since the sorbent particles will be rapidly entrained in the swirling secondary air from this outer secondary annulus they will be intimately mixed with the products of combustion as soon after passing the peak flame temperature zone as is feasible. This increases the efficiency of the sulfur capture and results in capture that is equal to or betterthan capture methods external to the burner throat.
- It is understood that several variations and additions may be made to the foregoing apparatus. For example, since the arrangement permits the admission of air at less than stoichiometric for further reductions in NO,, emissions, overfire air ports, orthe like can be provided as needed to supply air to complete the combustion. Also, the distribution of the
sorbent injectors 49 around the periphery of the burner can be varied to obtain optimum sulfur capture. Additionally, the burner levels which receive sorbent injectors are dependent on the number of burner levels, slagging characteristics of the coal ash and the gas temperature at the exit to the furnace's radiant zone. Boilers with three or more burner levels need only have the top two levels contain sorbent injectors. This is sufficient to provide an effective calcination zone for calcium- based sorbents along with a long residence time for sulfation reactions to occur prior to the furnace exit.
Claims (11)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US60470684A | 1984-04-27 | 1984-04-27 | |
US604706 | 1984-04-27 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0163423A1 EP0163423A1 (en) | 1985-12-04 |
EP0163423B1 true EP0163423B1 (en) | 1988-08-17 |
Family
ID=24420687
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19850302979 Expired EP0163423B1 (en) | 1984-04-27 | 1985-04-26 | Controlled flow, split stream burner assembly with sorbent injection |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0163423B1 (en) |
JP (1) | JPS6122105A (en) |
AU (1) | AU577366B2 (en) |
CA (1) | CA1254444A (en) |
DE (1) | DE3564481D1 (en) |
ES (1) | ES8605330A1 (en) |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2776572B2 (en) * | 1989-07-17 | 1998-07-16 | バブコツク日立株式会社 | Pulverized coal burner |
JPH04122677U (en) * | 1991-04-18 | 1992-11-04 | 三信工業株式会社 | Wire mesh for vibrating sieve |
JPH04126783U (en) * | 1991-04-27 | 1992-11-18 | 三信工業株式会社 | Wire mesh for vibrating sieve |
JP3140299B2 (en) * | 1994-06-30 | 2001-03-05 | 株式会社日立製作所 | Pulverized coal burner and its use |
CA2167341C (en) * | 1995-01-17 | 2000-03-21 | Joel Vatsky | Tiltable split stream burner assembly with gasket seal |
EP0836048B1 (en) * | 1996-10-08 | 2001-08-16 | Ansaldo Caldaie S.P.A. | Burner |
DE102011056655B4 (en) * | 2011-12-20 | 2013-10-31 | Alstom Technology Ltd. | Burner for burning a dusty fuel for a boiler with plasma ignition burner |
JP6813533B2 (en) * | 2018-05-22 | 2021-01-13 | 三菱パワー株式会社 | Burner and combustion equipment |
CN111495162B (en) * | 2020-04-26 | 2021-12-21 | 安徽顺达环保科技股份有限公司 | Silencing device and method for dry desulfurization and denitrification |
CN115121392B (en) * | 2022-07-27 | 2024-03-26 | 惠州市鼎泰欣科技有限公司 | Pulverized coal nozzle of blast furnace |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5236609A (en) * | 1975-09-16 | 1977-03-22 | Takeda Chem Ind Ltd | Process for preparation of alcohol and carbon monoxide |
DE2932676C2 (en) * | 1979-08-11 | 1983-01-27 | L. & C. Steinmüller GmbH, 5270 Gummersbach | Process for binding sulfur, chlorine and fluorine compounds during combustion |
US4400151A (en) * | 1980-06-04 | 1983-08-23 | Foster Wheeler Energy Corporation | Controlled flow, split stream burner assembly |
JPS58156104A (en) * | 1982-03-10 | 1983-09-17 | Hitachi Zosen Corp | Desulfurizing method for inside of furnace in solid combustion furnace |
-
1985
- 1985-04-22 AU AU41495/85A patent/AU577366B2/en not_active Ceased
- 1985-04-26 DE DE8585302979T patent/DE3564481D1/en not_active Expired
- 1985-04-26 CA CA000480198A patent/CA1254444A/en not_active Expired
- 1985-04-26 JP JP8909985A patent/JPS6122105A/en active Granted
- 1985-04-26 ES ES542628A patent/ES8605330A1/en not_active Expired
- 1985-04-26 EP EP19850302979 patent/EP0163423B1/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
ES8605330A1 (en) | 1986-03-16 |
JPH0225083B2 (en) | 1990-05-31 |
CA1254444A (en) | 1989-05-23 |
AU4149585A (en) | 1985-10-31 |
DE3564481D1 (en) | 1988-09-22 |
EP0163423A1 (en) | 1985-12-04 |
JPS6122105A (en) | 1986-01-30 |
ES542628A0 (en) | 1986-03-16 |
AU577366B2 (en) | 1988-09-22 |
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