JP2009216281A - Burner for pulverized fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burner for pulverized fuel can improve ignition performance by pulverized fuel of little volatile matter content, and continuously and stably keeping flame. <P>SOLUTION: This burner for pulverized fuel includes a nozzle body 6 opened toward a furnace 1 and jetting the pulverized fuel with the primary air for combustion, and a flow channel for secondary air for combustion concentrically formed around the nozzle body, block sections are formed along the circumferential direction of the flow channel of secondary air for combustion at prescribed intervals, so that non-circulation parts are formed on the flow channel for secondary air for combustion by the block sections to generate backflow phenomenon of a high temperature gas in the furnace. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pulverized fuel burner provided in a furnace that uses fine powder as fuel, such as a coal-fired boiler.

  A furnace using fine powder as a fuel, for example, a furnace using coal as a fuel, pulverized coal is pulverized by a pulverized coal machine into pulverized coal, and the pulverized coal is mixed with primary air, and then pulverized together with primary air. Some are supplied to a charcoal burner and ejected from the pulverized coal burner to a furnace to float and burn the pulverized coal.

  Secondary air for combustion heated to a required temperature (for example, 250 ° C. to 300 ° C.) is further supplied to the mixed flow of primary air and pulverized coal. The pulverized coal in the mixed stream is heated by secondary air and radiant heat from the inside of the furnace, emits volatile matter, and ignites to generate a flame.

  A conventional pulverized coal burner will be described with reference to FIG.

  In FIG. 5, reference numeral 1 denotes a furnace, and 2 denotes a furnace wall of the furnace 1.

  A throat 3 is provided on the furnace wall 2, a wind box 4 is attached to the counter-fired furnace 1 side of the furnace wall 2, and a pulverized coal burner 5 is provided concentrically with the throat 3 inside the wind box 4. .

  The pulverized coal burner 5 includes a nozzle main body 6 and a secondary air adjusting device 7 provided so as to surround the tip of the nozzle main body 6.

  The nozzle body 6 includes an outer cylinder nozzle 8, an inner cylinder nozzle 9 provided concentrically with the outer cylinder nozzle 8, and an oil burner 11 disposed on the center line of the inner cylinder nozzle 9.

  An outer cylinder base portion (end portion on the side of the counter-fired furnace 1) 8a of the outer cylinder nozzle 8 has a cylindrical shape whose cross-sectional diameter does not change, and an outer cylinder intermediate portion 8b continuous with the outer cylinder base portion 8a is connected to the furnace 1. The outer cylinder tip 8c continuous with the outer cylinder intermediate part 8b is a tapered cylinder whose diameter is reduced toward the furnace 1, and the outer cylinder is tapered. The taper angle of the distal end portion 8c is larger than that of the outer cylinder intermediate portion 8b, and the diameter is sharply reduced from that of the outer cylinder intermediate portion 8b.

  The inner cylinder cylindrical portion 9a of the inner cylinder nozzle 9 has a cylindrical shape whose cross-sectional diameter does not change up to the vicinity of the distal end of the outer cylinder intermediate portion 8b, and is an inner cylinder distal end portion that is continuous with the inner cylinder cylindrical portion 9a. 9c has a tapered cylindrical shape having a taper angle equivalent to that of the outer cylinder tip 8c. Between the outer cylinder nozzle 8 and the inner cylinder nozzle 9, a fuel conduction space 10 is formed in a hollow cylindrical space with the furnace 1 side end opened.

  A primary air introduction pipe 12 communicates with a base part (end part on the side of the counter-fired furnace 1) of the outer cylinder nozzle 8, and the primary air 14 and the primary air 14 are communicated with the primary air introduction pipe 12. The transported pulverized coal flows into the fuel conduction space 10 from the tangential direction, and is ejected from the tip while turning inside the fuel conduction space 10. Further, one end of a tertiary air introduction pipe 13 is opened at the base of the inner cylinder nozzle 9, and the other end of the tertiary air introduction pipe 13 is opened in the wind box 4 and is fed to the wind box 4. Combustion air is taken in and led to the inner nozzle 9 as auxiliary combustion air, that is, tertiary combustion air.

  The secondary air adjusting device 7 includes an auxiliary air adjusting mechanism 15 that houses the tip of the nozzle body 6 and a main air adjusting mechanism 16 that is provided concentrically outside the auxiliary air adjusting mechanism 15. .

  The auxiliary air adjustment mechanism 15 has a first air guide duct 18 that is reduced in diameter toward the tip, and an air volume adjusting blade 19 that is provided at equal intervals around the base of the first air guide duct 18. The adjustment blade 19 can be rotated synchronously about the rotation shaft 21.

  The main air adjusting mechanism 16 includes a second air guide duct 22 that is reduced in diameter toward the tip, and an air volume adjusting blade 23 that is provided at equal intervals around the base of the second air guide duct 22. The air volume adjusting blade 23 can be rotated synchronously about a rotating shaft 24.

  The tip of the second air guide duct 22 is continuous with the throat 3 and the tip of the first air guide duct 18 is in a position retracted from the inner wall surface of the furnace wall 2. The tip of the inner cylinder nozzle 9 is in a position further retracted from the tip of the first air guide duct 18.

  Briefly describing the combustion in the pulverized coal burner 5, the pulverized coal is supplied to the base of the fuel conduction space 10 from the primary air introduction pipe 12 together with the primary air 14. The primary air 14 flows toward the furnace 1 while turning in the fuel conduction space 10, is contracted in the process of passing through the fuel conduction space 10, and is ejected from the tip of the outer cylinder nozzle 8. The Secondary air 26, which is auxiliary combustion air, is heated to a required temperature and supplied to the wind box 4, and the secondary air 26 is adjusted in air volume by the air volume adjusting blade 23, and the second air guide duct. 22 is ejected into the furnace 1 together with the primary air 14 and the pulverized coal.

  The pulverized coal is heated by the secondary air 26 in the process of being ejected into the furnace 1, and is heated by receiving radiant heat from the furnace 1. By heating, the volatile matter is released from the pulverized coal, the volatile matter is ignited, and the flame is continuously maintained.

  A part of the secondary air 26 taken into the second air guide duct 22 is taken into the first air guide duct 18 through the air volume adjusting blade 19 and ejected as secondary auxiliary air. Is done. By adjusting the air volume of the air volume adjusting blade 23 and the air volume of the air volume adjusting blade 19, the state of the supply amount flow of the secondary air 26 is changed, and the combustion state of pulverized coal is adjusted.

  A part of the secondary air 26 is guided as the tertiary air 27 to the inner cylinder nozzle 9 through the tertiary air introduction pipe 13 and ejected from the inner cylinder nozzle 9. The combustion state of pulverized coal is adjusted by ejecting the tertiary air 27. Therefore, the combustion state of the pulverized coal is adjusted to be optimum by adjusting the secondary air 26 and the tertiary air 27.

  The oil burner 11 is used when igniting pulverized coal.

  For the conventional pulverized coal burner 5 described above, a pulverized coal such as a bituminous coal such as bituminous coal including a predetermined amount, for example, about 20% of volatile components, is used.

  However, in recent years, it has been demanded to use a worse fuel, for example, oil coke which is a residue after petroleum refining is used as the fuel. Oil coke has a low volatile content of about 10%, and in the conventional pulverized coal burner 5 described above, the temperature of the pulverized fuel ejected from the pulverized coal burner 5 is low, and a sufficient volatile content is not released. There is a problem that cannot be maintained. Further, when the flame is not maintained, there is a problem that NOx increases.

JP-A-8-145320

  In view of such circumstances, the present invention provides a pulverized fuel burner that improves ignitability with a finely pulverized fuel with a small amount of volatile matter and that maintains a flame continuously and stably.

  The present invention comprises a nozzle body that opens toward the furnace and ejects pulverized fuel together with the primary combustion air, and a combustion secondary air passage formed concentrically around the nozzle body, A blocking portion is provided at a predetermined interval along the circumferential direction of the combustion secondary air flow path, and the blocking portion forms a non-flow portion in the combustion secondary air flow path, The present invention relates to a pulverized fuel burner configured to generate a reverse flow phenomenon.

  The present invention also relates to a pulverized fuel burner having a variable range in which the blocking portion occupies the combustion secondary air flow path.

  The present invention also provides a movable ring that is concentrically rotatable with respect to the tip of the nozzle body, a movable guide blade is provided on the movable ring, a fixed guide blade is provided at the tip of the nozzle body, and the movable The pulverized fuel burner is configured such that the guide vane and the fixed guide vane each have a blocking portion orthogonal to the nozzle axis, and the overlapping state of the two blocking portions is changed by rotating the movable ring. It is related to.

  According to the present invention, the nozzle body is housed in a window box, an air guide duct is provided in the wind box concentrically with the tip of the nozzle body, and a movable ring is rotatably provided at the tip of the nozzle body. The movable ring is provided with a movable guide vane, the air guide duct is provided with a fixed guide vane, and the movable guide vane and the fixed guide vane each have a blocking portion orthogonal to the nozzle axis, and the movable guide vane The present invention relates to a pulverized fuel burner configured to change the overlapping state of the two blocking portions by rotating the ring.

  According to the present invention, there is provided a nozzle body that opens toward the furnace and injects pulverized fuel together with the combustion primary air, and a combustion secondary air passage formed concentrically around the nozzle body. And a blocking portion is provided at predetermined intervals along the circumferential direction of the combustion secondary air flow path, and a non-flowing portion is formed in the combustion secondary air flow path by the blocking portion, so that the high temperature in the furnace Since the gas back-flow phenomenon occurs, high-temperature exhaust gas in the furnace is drawn in, the pulverized fuel is heated by the exhaust gas, and even if it is a pulverized fuel with little volatile matter, the ignitability is improved and stable and reliable Is ignited and the flame is maintained.

  Further, according to the present invention, since the range that occupies the combustion secondary air flow path of the shut-off portion is variable, the strength of the reverse flow phenomenon of the high temperature gas in the furnace can be adjusted, and various volatile components can be varied. Fine powder fuel can be burned under appropriate conditions.

  According to the present invention, a movable ring is provided concentrically with the tip of the nozzle body so as to be rotatable, a movable guide blade is provided on the movable ring, and a fixed guide blade is provided at the tip of the nozzle body. Since the movable guide vane and the fixed guide vane each have a blocking portion orthogonal to the nozzle axis, and by rotating the movable ring, the overlapping state of the two blocking portions is changed. The range that occupies the flow path for the secondary air for combustion in the shut-off section changes, the strength of the reverse flow phenomenon of the high-temperature gas in the furnace can be adjusted, and pulverized fuel with different volatile components can be burned under appropriate conditions it can.

  According to the invention, the nozzle body is housed in a window box, and an air guide duct is provided in the wind box concentrically with the tip of the nozzle body, and a movable ring is rotatable at the tip of the nozzle body. The movable ring is provided with a movable guide vane, the air guide duct is provided with a fixed guide vane, and the movable guide vane and the fixed guide vane each have a blocking portion orthogonal to the nozzle axis, By rotating the movable ring, the overlapping state of the two shut-off portions is changed, so that the range of the shut-off portion occupying the secondary air flow path for combustion changes, and the reverse flow phenomenon of the hot gas in the furnace It is possible to adjust the strength of the pulverized component, and it is possible to burn fine powder fuels having different volatile components under appropriate conditions.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  1 and 2 show an example of a pulverized coal burner in which the present invention is implemented. In FIG. 1, the same components as those shown in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted.

  The pulverized coal burner 5 includes a nozzle body 6 and a secondary air adjusting device 31, the pulverized coal burner 5 is provided concentrically with the throat 3 opened in the furnace wall 2, and the pulverized coal burner 5 is disposed in the wind box 4. It is stored.

  The wind box 4 is blown with secondary air 26 from a forced air blower (not shown), and the air volume of the secondary air 26 is controlled by the forced air blower so that the air pressure is adjusted to the air flow necessary for combustion. Is controlled.

  The nozzle body 6 includes an outer cylinder nozzle 8 and an inner cylinder nozzle 9 provided concentrically with the outer cylinder nozzle 8, and a hollow cylinder shape is provided between the outer cylinder nozzle 8 and the inner cylinder nozzle 9. The fuel conduction space 10 is formed.

  A base portion of the nozzle body 6 protrudes from the window box 4 and a primary air introduction pipe 12 is communicated with the outer cylinder base portion 8a. The downstream end of the tertiary air introduction pipe 13 is communicated with the end of the inner cylinder nozzle 9, and the upstream end is communicated with the wind box 4. The primary air introduction pipe 12 is connected to the pushing ventilator (not shown) via a pulverized coal machine (not shown), and the primary air 14 containing pulverized coal from the primary air introduction pipe 12 is The tertiary air introduction pipe 13 is introduced into the fuel conduction space 10 and takes in a part of the secondary air 26 and introduces it into the inner cylinder nozzle 9.

  On the furnace 1 side of the wind box 4, the secondary air adjustment device 31 is provided concentrically with the tip of the pulverized coal burner 5.

  The secondary air conditioner 31 will be described.

  An air guide duct 32 is provided concentrically with the outer cylinder nozzle 8 on the surface of the windbox 4 facing the furnace 1, and the air guide duct 32 has a substantially tapered shape whose diameter is reduced toward the furnace 1 side. The tip portion is connected to the throat 3.

  A movable ring 33 is rotatably provided in the air guide duct 32 so as to be concentric with the air guide duct 32. The required number of movable guide vanes 34 are provided on the inner surface of the movable ring 33 at equal angular intervals, for example, 90 ° intervals. Is provided.

  The movable guide vane 34 extends toward the center of the pulverized coal burner 5, and a flow guide portion 35 (see FIG. 3A) provided along the flow direction of the secondary air 26 and the flow guide. A flow blocking portion 36 provided at the upstream end of the portion 35 and orthogonal to the flow guide portion 35 (perpendicular to the axis of the pulverized coal burner 5) is configured to rotate integrally with the movable ring 33. ing.

  The flow guide part 35 is inclined with respect to the first rectification part 35a (see FIG. 3A) parallel to the axis of the pulverized coal burner 5 and the axis, and makes the swirl flow to the secondary air 26. It is formed by the second rectification part 35b (see FIG. 3A) to be formed.

  Fixed guide vanes 37 are provided at the front end portion of the outer cylinder nozzle 8 at the same angular interval, for example, 90 ° intervals as the movable guide vanes 34.

  The fixed guide vane 37 has substantially the same shape as the movable guide vane 34, and the fixed guide vane 37 extends radially from the center of the pulverized coal burner 5 and flows along the flow direction of the secondary air 26. And a flow blocking portion 39 that is provided at the upstream end of the flow guide portion 38 and orthogonal to the flow guide portion 38 (perpendicular to the axis of the pulverized coal burner 5). In order not to interfere with the rotation of the movable ring 33, a gap is formed between the outer peripheral end of the fixed guide vane 37 and the inner surface of the movable ring 33, and the flow blocking portion 39 is located with respect to the flow blocking portion 36. It is displaced in the axial direction.

  Further, the flow guide portion 38 is formed by the first rectifying portion 35a and the second rectifying portion 35b, similarly to the movable guide vane 34.

  The movable guide vane 34 and the fixed guide vane 37 constitute a variable blocking portion 41 (see FIG. 3 and FIG. 4) as a pair, and the movable guide vane 34 and the fixed guide vane 37 of the variable blocking portion 41 adjacent to the movable guide vane 34. Thus, the flow path 42 (see FIGS. 3 and 4) is formed.

  A ring gear 43 is provided at the upstream end of the movable ring 33, a drive gear 44 is engaged with the ring gear 43, a drive shaft 45 is connected to the drive gear 44, and the drive shaft 45 is connected to the drive gear 45. It is connected to a motor 47 provided on the front plate 46 of 44.

  By rotating the motor 47, the ring gear 43 is rotated via the drive shaft 45 and the drive gear 44, and the movable ring 33 rotates together with the ring gear 43.

  The movable guide vane 34 and the fixed guide vane 37 rotate in the forward and reverse directions, and come close to and away from each other.

  3 and 4 show the relationship between the movable guide vane 34 and the fixed guide vane 37. FIGS. 3A and 4A show the movable guide vane 34 and the fixed guide vane 37. FIG. 3B and FIG. 4B show a state in which the movable guide vane 34 and the fixed guide vane 37 are most separated from each other.

  In the closest state, the flow path section of the flow path 42 is the maximum, and the size of the variable blocking portion 41 blocking the flow path 42 is the minimum. In the farthest state, the flow path section of the flow path 42 is the smallest, and the size that the variable blocking portion 41 blocks the flow path 42 is the largest.

  If the amount of secondary air supplied is the same, the flow rate of the secondary air 26 is small in the closest state, and the flow rate of the secondary air 26 is large in the most distant state.

  Next, the operation of the secondary air adjusting device 31 will be described.

  When pulverized fuel, for example, pulverized coal with a relatively small amount of volatile matter is supplied, the movable ring 33 is rotated by the motor 47 so that the movable guide blade 34 and the fixed guide blade 37 are brought close to each other.

  The flow path cross section of the flow path 42 becomes larger, and the flow velocity of the secondary air 26 passing through the flow path 42 becomes smaller. Further, the flow path blocking range by the variable blocking section 41 is reduced. A non-flowing portion of the secondary air 26 is generated between the secondary air 26 flowing on both sides of the variable blocking portion 41 at a downstream portion of the variable blocking portion 41, and a vortex is generated. The reverse flow phenomenon of the hot gas in the furnace occurs due to the generation of the vortex, and the furnace gas is drawn from the furnace 1.

  The in-furnace gas is high temperature, heats the pulverized coal ejected together with the primary air 14, and ignites reliably even if it is a fuel with a small amount of volatile matter. Therefore, even a pulverized fuel with a small amount of volatile matter is ignited reliably and the flame is stably maintained. In addition, since the interruption | blocking range of the said variable interruption | blocking part 41 is small, a vortex is small and the inhalation amount of the gas in a furnace from the said furnace 1 is small.

  Next, when pulverized fuel with a very small volatile content is supplied, the movable ring 33 is rotated by the motor 47 via the ring gear 43, and the movable guide vane 34 and the fixed guide vane 37 are moved. Get away to the maximum.

  The channel of the channel 42 is narrowed, and the channel blocking range by the variable blocking unit 41 is increased. The flow velocity of the secondary air 26 passing through the flow path 42 is increased, the vortex generated between the secondary air 26 flowing on both sides of the variable blocking portion 41 is increased, and the backflow phenomenon of the hot gas in the furnace is also remarkable. It becomes. For this reason, the amount of in-furnace gas drawn from the furnace 1 is increased, and the pulverized fuel is heated to a higher temperature by the in-furnace gas, and it becomes possible to ignite the pulverized fuel with less volatile content and to maintain the flame after ignition.

  Thus, by adjusting the amount of separation between the movable guide vane 34 and the fixed guide vane 37 in the variable shut-off portion 41, an optimal combustion state can be obtained for various pulverized fuels with little volatile content. .

  When there is no change in the volatile matter contained in the pulverized fuel to be supplied, a flow blocking plate (corresponding to the flow blocking unit 36 and the flow blocking unit 39) having a required area is connected to the outer cylinder nozzle 8 and the air. It may be provided at a required circumferential interval between the guide duct 32 and the guide duct 32.

  Various means for rotating the movable ring 33 or the movable guide vane 34 are conceivable. For example, a cylinder or the like may be used, or the position may be changed manually.

  Although the movable ring 33 is rotatably provided in the air guide duct 32, the movable ring 33 may be rotatably provided at the tip of the outer cylinder nozzle 8, and the fixed guide vane 37 may be provided in the air guide duct 32. Good.

It is sectional drawing which shows an example of the pulverized coal burner which concerns on this invention. It is A arrow directional view of FIG. (A) and (B) are operation | movement explanatory drawings of the variable interruption | blocking part used for the pulverized coal burner of this invention. (A) and (B) are operation | movement explanatory drawings of the variable interruption | blocking part used for the pulverized coal burner of this invention. It is sectional drawing which shows the conventional pulverized coal burner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace 4 Wind box 5 Pulverized coal burner 6 Nozzle body 8 Outer cylinder nozzle 14 Primary air 26 Secondary air 32 Air guide duct 33 Movable ring 34 Movable guide vane 36 Flow blocking part 37 Fixed guide vane 39 Flow blocking part 43 Ring gear 44 Drive gear 47 Motor

Claims (4)

  A nozzle body that opens toward the furnace and injects pulverized fuel together with the primary air for combustion, and a combustion secondary air flow path formed concentrically around the nozzle body. A blocking portion is provided at a predetermined interval along the circumferential direction of the secondary air flow path, and the non-flowing portion is formed in the combustion secondary air flow path by the blocking portion, causing a reverse flow phenomenon of the high temperature gas in the furnace. A burner for pulverized fuel, characterized in that it is configured.   The pulverized fuel burner according to claim 1, wherein a range occupying the combustion secondary air flow path of the blocking portion is variable.   A movable ring is provided concentrically with the tip of the nozzle body so as to be rotatable, a movable guide blade is provided on the movable ring, a fixed guide blade is provided at the tip of the nozzle body, the movable guide blade, and the fixed 2. The pulverized fuel burner according to claim 1, wherein each of the guide vanes has a blocking portion orthogonal to the nozzle axis, and the overlapping state of the two blocking portions is changed by rotating the movable ring.   The nozzle body is housed in a window box, the wind box is provided with an air guide duct concentrically with the tip of the nozzle body, and a movable ring is rotatably provided at the tip of the nozzle body. A movable guide vane is provided, a fixed guide vane is provided in the air guide duct, the movable guide vane and the fixed guide vane each have a blocking portion orthogonal to the nozzle axis, and the movable ring is rotated. The pulverized fuel burner according to claim 1, wherein the overlapping state of the two blocking portions is changed.

Images