JP4394561B2 - After-air nozzle for two-stage combustion boiler and two-stage combustion boiler using the same - Google Patents

Description

  The present invention relates to an after air nozzle for a two-stage combustion boiler and a structure of a two-stage combustion boiler using the same.

  Boilers are required to reduce the concentration of nitrogen oxides (NOx), and a two-stage combustion method is applied to meet this demand. This method is a method of supplying air for complete combustion from an after air nozzle after burning fuel in a state of air shortage. Several structures have been proposed for the after-air nozzle in order to improve air mixing and combustion conditions.

  For example, as described in FIG. 1 of Patent Document 1 (Japanese Patent Laid-Open No. 10-122546), the after air nozzle has a contracted portion in which the outer diameter of the air flow path gradually decreases toward the air outlet. As shown in FIG. 1 of Patent Document 2 (Japanese Patent Laid-Open No. 9-112878), a structure having a louver for changing the air ejection direction inside the flow path, Patent Document 3 (Japanese Patent Laid-Open No. 2003-254510). A structure in which the center portion of the after-air air is ejected as a straight flow as shown in FIG. 10 and a structure in which it is ejected as a swirl flow as shown in FIG. 11 of Patent Document 3 (Japanese Patent Laid-Open No. 2003-254510) are proposed. However, recent boilers are required to reduce NOx and CO at the same time. However, in these configurations, only NOx or CO can be reduced.

Japanese Patent Laid-Open No. 10-122546 JP-A-9-112878 JP 2003-254510 A

  The present invention proposes a structure of an after-air nozzle that can simultaneously reduce NOx and CO.

The after-air nozzle of the two-stage combustion boiler of the present invention is directed toward a wind box outer cylinder surrounding the outer periphery of the after air nozzle, a wind box opening into which combustion air flows, and an air outlet for supplying air to the boiler. a vena contracta which passage outside diameter is reduced, and a flow path cross-sectional area changing device for changing the flow path cross-sectional area of the vena contracta, the air flow path of the flow path cross-sectional area changing device in the after-air nozzles Provided in the flow path cross-sectional area changing device, a member defining the minimum flow area of the contracted portion is provided, and the member defining the minimum flow area is moved in the flow path direction to reduce the contraction. A flow path cross-sectional area of the flow portion is configured to be changeable, and a slide member that adjusts the amount of combustion air flowing into the after air nozzle from the wind box opening is attached to the wind box outer cylinder, and the window Characterized in that the amount of air flowing from the de box opening to vary the area of the windbox opening so as to maintain constant.
The two-stage combustion boiler of the present invention is provided with a furnace that burns fuel and air and generates steam by the thermal energy of the combustion gas, and an upstream side in the gas flow direction of the furnace. In the two-stage combustion boiler having a burner to be burned and an after air nozzle that is provided downstream of the furnace in the gas flow direction and downstream of the burner and supplies air for completely burning the combustion gas, A plurality of after-air nozzles installed in the furnace are a flow path toward a wind box outer cylinder surrounding an outer periphery of the after-air nozzle, a wind box opening into which combustion air flows, and an air outlet for supplying air to the boiler And a flow path cross-sectional area changing device that changes a flow path cross-sectional area of the flow reducing portion. A member that defines the channel area is provided inside the after air nozzle, and the member that defines the minimum channel area of the contracted portion is moved in the direction of the channel to change the channel cross-sectional area of the contracted portion. A slide member for adjusting the amount of combustion air flowing into the after-air nozzle from the window box opening is attached to the window box outer cylinder to keep the amount of air flowing from the window box opening constant. Thus, the area of the window box opening is changed.

  By using the after air nozzle of the present invention, NOx and CO in the two-stage combustion boiler can be simultaneously reduced. Further, since the operation direction of the adjusting device used at the time of combustion adjustment and the expected effect on the combustion performance are clear, the optimum adjustment of NOx and CO is facilitated.

Hereinafter, the structure of the after-air nozzle of the present invention and the method of using the same will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a longitudinal sectional view showing an example of an embodiment of an after air nozzle according to the present invention. The after air nozzle is surrounded by a wind box outer cylinder 10, and combustion air flows from an opening 12 provided at a rear portion of the wind box 10. The air flows 14a to 14f flow along arrows, and are ejected from the ejection port 16 to the combustion space 18 in the furnace. The ejected air is mixed with the combustible gas in the furnace combustion space 18 to burn the combustible gas. A water pipe 20 is provided around the jet nozzle 16. A contraction member 22 is provided on the outlet 16 side of the after air nozzle. The contraction member 22 has a structure in which the diameter gradually decreases toward the jet port 16 side.

  By this contracted member 22, the air flow 14 a to 14 f indicated by arrows is given a velocity component toward the nozzle central axis, and the contracted portion 24 is formed. A member 26 that defines the minimum flow path area of the contracted flow portion 24 is provided near the inlet of the contracted flow portion 24. The flow velocity of the air in the contracted part 24 is defined by the area of the minimum flow path 28 of the contracted part 24. In the configuration of FIG. 1, the minimum flow path 28 of the contracted flow portion 24 is formed at the tip of the member 26 that defines the minimum flow path area of the contracted flow portion 24.

  The member 26 that defines the minimum flow path area of the contracted flow portion 24 in FIG. 1 has a configuration in which the outer diameter gradually decreases toward the jet port 16. This is to reduce the flow disturbance in the contracted flow portion 24. By reducing the disturbance, it is easy to suppress a rapid increase in NOx.

  The member 26 that defines the minimum flow path area of the contracted flow portion 24 is fixed to a support member 30 that supports the member 26 that defines the minimum flow path area of the contracted flow portion 24. The support member 30 that supports the member 26 that defines the minimum flow path area of the contracted flow portion 24 is fixed to the slide ring 32. The slide ring 32 is attached to the inner cylinder 34. The slide ring 32 and the inner cylinder 34 are not fixed to each other, and the slide ring 32 is movable in the direction toward the windbox outer wall 36 in FIG.

  By moving the slide ring 32, the support member 30 that supports the member 26 that defines the minimum flow path area of the contracted flow portion 24 and the member 26 that defines the minimum flow path area of the contracted flow portion 24 also move simultaneously. When the member 26 that defines the minimum flow path area of the contracted flow part 24 is moved, the area of the minimum flow path 28 of the contracted flow part 24 changes. At this time, the inner diameter of the contracted flow portion 24 is changed while the outer diameter is constant, and as a result, the cross-sectional area perpendicular to the nozzle center axis, which is the flow path cross-sectional area of the reduced flow portion 24, changes.

  As will be described later, NOx and NOx can be obtained by providing a contracted flow portion 24 in which the outer diameter of the flow path decreases toward the air outlet 16 and adjusting the change in the cross-sectional area of the flow path without changing the outer diameter of the flow path. It becomes possible to reduce CO simultaneously. When the guide roller 38 is attached to either the slide ring 32 or the inner cylinder 34, the slide ring 32 can be moved smoothly. By attaching the slide ring moving rod fixing mechanism 40, the slide ring moving rod 42, and the handle 44 to the slide ring 32, the minimum flow path area of the constricted portion 24 is formed from the outside (left side in FIG. 1) of the wind box outer wall 36. Can be moved.

  When the slide ring 33 is attached to the windbox outer cylinder 10 and the area of the windbox opening 12 is changed, the total amount of air flowing into the after-air nozzle can be changed. When the change in the total air amount is unnecessary or can be changed by another method, the slide ring 33 may not be attached to the windbox outer cylinder 10.

  An overheat prevention material 46 is provided inside the member 26 that defines the minimum flow path area of the contracted flow portion 24. This is to prevent the support member 30 that supports the member 26 that defines the minimum flow path area of the contracted flow portion 24 from being burned out by the radiant heat from the flame formed in the combustion space 18 in the furnace. When the flame radiant heat formed in the in-furnace combustion space 18 is weak, or when the support member 30 can be cooled by other methods, the overheat prevention material 46 is not necessarily required.

  When the guide 48 is attached to the slide ring 32, the core of the member 26 that defines the minimum flow path area of the contracted flow portion 24 is not easily displaced when the slide ring 32 is moved. Further, the support member 30 that supports the member 26 that defines the slide ring 32 and the minimum flow path area of the contracted portion can be firmly fixed. Moreover, it is easy to rectify the air flow. The guide 48 has an inner end fixed to the outside of the slide ring 32, and an outer end is slidable in contact with the inner surface of the windbox outer cylinder 10.

  2 and 3 show the positional relationship between the member 26 and the contracted member 22 when the member 26 that defines the minimum flow path area of the contracted portion 24 is moved back and forth. The positional relationship will be described with reference to the starting position of the contracted portion 24 (cross section A-A ′ in FIG. 1). When moved to the jet port 16 side as much as possible (FIG. 2), the tip of the member 26 is positioned closer to the jet port 16 than the starting position of the contracted portion 24. At this time, the movement of the guide 48 is restricted by the stepped portion 49 provided at the connecting portion between the flow reducing portion 24 and the windbox outer cylinder 10. On the other hand, when it is moved to the maximum extent toward the windbox outer wall 36 side, the tip of the member 26 is closer to the windbox outer wall 36 side than the starting position of the contracted portion 24. The movement range may be different from that shown in FIGS. 2 and 3, but in the experiments by the inventors described later, NOx and CO are simultaneously reduced when the movement range shown in FIGS. 2 and 3 is used. Was the easiest.

  FIG. 4 shows a cross-sectional view of the nozzle of FIG. 1 in the A-A ′ direction and the B-B ′ direction, and FIG. 5 shows a cross-sectional view in the C-C ′ direction. 1 corresponds to a cross-sectional view in the G-G ′ direction of FIGS. 4 and 5. FIG. 6 is a modification of the cross-sectional view in the A-A ′ direction and the B-B ′ direction in FIG. 1. In the experiments of the inventors described later, a nozzle having a circular cross section was used, but the same effect can be expected even when a rectangular nozzle as shown in FIG. 6 is used.

FIG. 7 is a longitudinal sectional view of an after air nozzle for explaining a modification of the embodiment of the present invention shown in FIG. Compared to FIG. 1, the shape of the member 26 that defines the minimum flow path area of the contracted flow portion 24 is different. That is, the outer peripheral surfaces of the members 26 and 46 in FIG. 1 become narrower toward the combustion space 18 in the furnace, but in FIG. 7, they extend in parallel and are flat. The necessary condition of the member 26 is that the area of the minimum flow path 28 of the contracted flow portion 24 can be changed by moving the member. As long as this condition is satisfied, the shape shown in FIG. 7 may be used.
(Embodiment 2)
FIG. 8 is a longitudinal sectional view showing Embodiment 2 of the after air nozzle of the present invention. There is no inner cylinder 34 for moving the member 26 that defines the minimum flow path area of the contracted flow part 24, the support member 30 of the member 26 that defines the minimum flow path area of the contracted flow part 24, and the contracted flow part The difference from FIG. 1 is that it has a flow path for cooling air for cooling 24. The other components having the same reference numerals as those in FIG. 1 have the same functions although the explanation is omitted.

  The slide ring 32 is movably attached to the inside of the wind box outer cylinder 10. The point that the slide ring 32 is moved via the slide ring moving rod fixing mechanism 40, the slide ring moving rod 42, and the handle 44, and that the slide ring 32 can be easily moved by attaching the guide roller 38 are the same as in FIG. It is. In the configuration of FIG. 8, since air can be introduced into the inside of the slide ring 32, air for cooling the support member 30 of the member 26 that defines the minimum flow path area of the contracted flow portion 24 can be introduced.

  The member 26 that defines the minimum flow path area of the contracted flow portion 24 can move back and forth as in FIG. Although the angle of the contracting member 22 and the member 26 that defines the minimum flow path area of the contracted portion are different, the area of the minimum flow path 28 of the contracted flow portion 24 can be changed without changing the outer diameter of the contracted flow portion 24. The NOx / CO performance equivalent to that in FIG. 1 can be expected. Cooling air holes 50 and 52 are provided in the support member 30 that supports the member 26 that defines the minimum flow path area of the contracted flow portion 24.

  Part of the air flows 14 a and 14 d introduced from the window box opening 12 becomes the cooling air flows 54 a to 54 c and is discharged from the cooling air holes 52. In the process, the member 30 can be cooled by colliding with the support member 30 that supports the member 26 that defines the minimum flow path area of the contracted flow portion 24. Further, the air flows 54d and 54e discharged from the cooling air hole 50 collide with the member 26 that defines the minimum flow path area of the contracted flow portion 24, and the member 26 can be cooled.

  Further, a cooling air guide plate 56 is provided in the vicinity of the contracted flow portion 24. Cooling air 54 f and 54 g flows between the cooling air guide plate 56 and the contracting member 22, and the contracting member 22 can be cooled. Moreover, since this cooling air 54f and 54g flows on the outermost peripheral side of the jet nozzle 16, it can be used also for removing the coal ash adhering to the circumference | surroundings of the contracted flow member 22. FIG.

  9 is a cross-sectional view taken along the line D-D ′ of FIG. 8. The cooling air holes 50 and 52 include a plurality of circular small holes, slit-shaped openings, and the like. FIG. 9 shows an example in which a plurality of circular small holes are provided. FIG. 10 is a modification of FIG. 8 and has a structure in which the amount of air for cooling the contraction member 22 can be adjusted. A cooling air inlet 58 is provided in the windbox outer cylinder 10. A movable cooling air adjusting guide sleeve 60 is provided around the cooling air inlet 58 to adjust the amount of cooling air.

When the amount of coal ash adhering to the periphery of the spout 16 increases, the amount of air flowing between the contraction member 22 and the cooling air guide plate 56 is temporarily increased to facilitate removal of the adhering ash. be able to. The angle of the contracting member 22 may change in the middle of the contracting part 24. The shape of the guide 48 may be changed as shown in FIG. 10 for reasons such as restrictions in producing the nozzle. In the configuration of FIG. 10, the angle near the inlet of the contracted portion 24 is large, and the angle near the outlet of the contracted portion 24 is small. The shape of the guide 48 has a structure in which a part of the outer peripheral portion is cut out. When the shape of the guide 48 is as shown in FIG. 10, the turbulence of the air flow flowing into the contracted flow portion 24 can be reduced, which is effective in reducing NOx.
(Embodiment 3)
FIG. 11 is a cross-sectional view showing an example of an embodiment of the after-air nozzle of the present invention. With the nozzle structure having the inner cylinder 34, cooling air can be introduced into the inner cylinder 34 through the air holes 61. A slide ring inner cylinder 62 is attached to the outside of the inner cylinder 34, and a slide ring outer cylinder 64 is attached to the inside of the wind box outer cylinder 10. The slide ring inner cylinder 62 and the slide ring outer cylinder 64 are connected and fixed by a guide 48. With this structure, the movable part can be lightened.

  In the structure of FIG. 11, an overheat preventing material 46 is provided by a support member 65 on a part of the inner cylinder 34 on the jet nozzle 16 side. If the overheat preventing material 46 is formed of a ceramic fireproof / insulating material or the like, the weight of the inner cylinder 34 becomes heavy, and thus the heavy overheat preventing material 46 is difficult to use for the movable part. With the structure as shown in FIG. 11, the member 26 that defines the minimum flow area of the contracted portion can be moved without moving the overheat preventing material 46. A cooling promotion plate 66 is attached to the member 26 that defines the minimum flow path area of the contracted flow portion 24. Thereby, the member 26 which prescribes | regulates the minimum flow path area of a constriction flow part can be cooled with small air quantity.

  The slide ring moving rod fixing mechanism 40 and the slide ring moving rod 42 are fixed to the slide ring inner cylinder 62, the slide ring outer cylinder 64, or the guide 48 (in FIG. 11, the slide ring inner cylinder 62). A slide ring moving device 68 is attached to the slide ring moving rod 42. When the slide ring mover 68 is moved, the member 26 that defines the minimum flow path area of the contracted portion 24 moves.

  The slide ring moving device 68 is connected to a threaded rotating shaft 70, and by rotating the threaded rotating shaft 70, the slide ring moving device 68 moves in the direction of the jet port 16 or the direction of the wind box outer wall 36. To do. A rotary bearing 52 is attached to one end of the threaded rotary shaft 70. A turntable 74 is attached to the other tip.

  The turntable 74 is connected to the rotation handle 76 via a belt or chain 78. When the rotation handle 76 is rotated, the turntable 74 also rotates. The rotary handle 76 is connected to the rotary shaft 80 so that it can rotate smoothly. The advantage of this structure is that adjustment during combustion is easy. When it is desired to reduce NOx, the rotary handle 76 may be rotated so that the member 26 defining the minimum flow path area of the contracted flow portion 24 moves in the direction of the jet port 16. When it is desired to reduce CO, the rotary handle 76 may be rotated in the reverse direction.

  When the slide ring outer cylinder 64 is moved, a part of the window box opening 12 can be closed. Thereby, even if the member 26 that defines the minimum flow path area of the contracted flow portion 24 is moved, the amount of air flowing in from the wind box opening 12 can be kept constant. If the flow path cross-sectional area of the contracted flow portion 24 is reduced, the flow path resistance at this portion increases and air does not flow easily.

  In the configuration of FIG. 11, at this time, the flow path cross-sectional area of the windbox opening 12 is increased, and the flow path resistance of this portion is reduced. The reverse is true when the cross-sectional area of the flow-reduced portion 24 is increased. That is, in the entire after-air nozzle, when the flow resistance of a part is increased, the flow resistance of the other part is reduced.

  If the size and shape of the window box opening 12 are optimized, it is possible to keep the flow path resistance constant when viewed by the entire after-air nozzle even if the flow path cross-sectional area of the contracted flow part 24 is changed. Note that this configuration is not necessarily required when the air flow rate does not need to be kept constant or when the air flow rate can be adjusted by another method.

FIG. 12 is a view seen from the windbox outer wall 36 side. A plate 61 is provided in the vicinity of the rotary handle to describe the effect that can be expected in the rotational direction. Since the contents of the operation and the expected effect are clearly understood, even an unskilled operator will not make a mistake in the operation. 13 is a cross-sectional view taken along the line EE ′ of FIG.
(Embodiment 4)
FIG. 14 is a longitudinal sectional view showing an example of an embodiment of the after-air nozzle of the present invention.

  The member 26 that defines the minimum flow path area of the contracted flow portion 24 has a replaceable structure. A support member 30 that defines the minimum flow path area of the contracted flow portion 24 is attached to the removable inner cylinder 88 with removable bolts 86a and 86b. The removable inner cylinder 88 is fixed to the removable windbox outer plate 90, and the windbox outer plate 90 is attached to the windbox outer wall 36 by detachable bolts 92a and 92b.

In this configuration, by removing the bolts 86a and 86b, the member 26 that defines the minimum flow area of the contracted portion 24 can be exchanged from the outside of the windbox outer wall 36 (left side in FIG. 14). FIG. 15 shows a state in which the member 26 that defines the minimum flow path area of the contracted flow portion 24 is replaced. By preparing and exchanging several members 26 in advance, the flow path cross-sectional area of the contracted portion 24 can be easily changed. In this embodiment, the removable inner cylinder 88 includes air holes 91a, 91b, 91c, and 91d, and the air flows 93a, 93b, 93c, and 93d circulate through the air holes 91a to 91d, respectively.
(Embodiment 5)
FIG. 16 is a cross-sectional view showing an example of an embodiment of an after air nozzle of the present invention. In this structure, the nozzles 94 and the straight nozzle 96 are two nozzles. Since there is no object at the center of the after air nozzle, the cooling structure is simplified. By moving the slide ring 32 back and forth, the channel cross-sectional area at the outlet of the contracted portion 24 is changed. FIG. 17 is a modification of FIG. 16, and the installation position of the slide ring 32 is changed.

  The effect of the present invention was verified by a combustion experiment. The verified object is an after air nozzle similar to the configuration of FIGS. As a comparison object, an experiment using the following five types of nozzles was also performed.

(1) Nozzle having a configuration similar to that shown in FIG.
(2) Nozzle having a configuration similar to that in FIG. 7 but in which the flow path of the contracted portion cannot be changed (contracted nozzle 2)
(3) Straight / swivel nozzle (straight / swivel nozzle) having a configuration similar to FIG.
(4) Straight-ahead nozzle (straight-ahead nozzle 1) having a configuration similar to FIG.
(5) A straight nozzle (straight nozzle 2) having a configuration similar to that of FIG.
18 to 20 show the concept of the after-air nozzle to be compared. In the straight / swirl nozzle of FIG. 18, the swirl vanes 98a and 98b swirl the air flows 99a and 99b on the outer peripheral side. The straight nozzle 1 in FIG. 19 is an example of the simplest nozzle configuration. In the straight nozzle 2 of FIG. 20, the nozzle has a multi-tube structure. The flow path cross-sectional area of the nozzle can be changed by opening and closing the dampers 100a to 100c. The point that the channel cross-sectional area can be changed is the same as that of the present invention, but the channel shape is different. In the straight nozzle 2, the outer diameter of the air channel changes when the channel cross-sectional area is changed.

  The result of the verification experiment is shown in FIG. In the experiment, the fuel supply amount, air supply amount, and the air ratio between the burner section and the entire furnace were kept as constant as possible, and the performance of the nozzles alone was compared. The performance was evaluated by the concentration of NOx and CO in the exhaust gas at the furnace outlet. The NOx concentration was compared with a 6% O2 conversion value, and the CO concentration was compared with a 3% O2 conversion value.

  The performance of NOx and CO when using the five types of nozzles to be compared was generally between the broken lines 108 and 109. On the other hand, the performance when using the nozzle of the present invention was approximately the value indicated by the curve 107. With the configuration of the present invention, the CO concentration can be significantly reduced. Even with the best value of NOx performance, the configuration of the present invention was superior to the configuration to be compared. From this result, it was found that NOx and CO can be simultaneously reduced by the configuration of the present invention.

  Symbol 102 is the result of the contracted flow nozzle 1, and symbol 103 is the result of the contracted flow nozzle 2. Compared with other nozzles to be compared, the performance of NOx and CO was not excellent. Sometimes it was inferior. It was found that NOx and CO could not be reduced at the same time simply by using a flow path shape having a contracted flow portion.

  Symbol 104 is the result of the straight nozzle 2. The performance of NOx and CO was not so excellent as compared with other comparative nozzles that cannot change the flow path area. Although CO could be reduced as compared with the straight nozzle 1, NOx increased at this time. Although one of NOx and CO performance can be improved by changing the flow channel area, NOx and CO cannot be reduced simultaneously with this configuration alone.

  Symbol 106 is the result of the straight nozzle 1. The nozzle diameter of this nozzle is the same as that of the nozzle of the present invention. It has been found that the performance of NOx and CO is not determined only by the nozzle diameter.

  The nozzle of the present invention was superior in NOx and CO performance to the straight nozzle 2. Further, from the comparison between the results of the reduced flow nozzle 1 and the reduced flow nozzle 2 and the result of the nozzle of the present invention, in the nozzle having the reduced flow portion, it is possible to change the flow passage area so that NOx and CO performance can be changed. It was found that the improvement effect was great.

From the above experimental results, it was found that the following configuration is a necessary condition for simultaneously reducing NOx and CO.
The nozzle configuration must have a constricted part in front of the spout.
The flow path of the contraction part can be changed.
The cross-sectional area of the air flow path can be changed without changing the outer diameter of the air flow path.
(Embodiment 6)
FIG. 22 is an example of an embodiment of an after air nozzle of the present invention, and is a configuration diagram of a pulverized coal combustion furnace to which the after air nozzle of the present invention is applied. The wall of the furnace is surrounded by an upper furnace ceiling 110, a lower hopper 112, a side furnace front wall 114, a furnace rear wall 116, and a furnace side wall 136 (described in FIG. 23). No water pipe is installed. A part of the combustion heat generated in the furnace combustion space 18 is absorbed by the water pipe. The combustion gas generated in the furnace combustion space 18 flows upward from below and is discharged as a gas 118 after combustion. The gas 118 after combustion passes through a rear heat transfer unit (not shown), and the heat contained in the gas is further recovered here.

  A burner 120 is installed in the lower part of the furnace, where an air-deficient flame 122 is formed. The coal is pulverized to about 150 μm or less by a pulverizer (not shown), and then conveyed by air, and the burner primary air and pulverized coal 124 are ejected from the burner into the furnace. The secondary and tertiary air 126 for the burner is also ejected from the burner through the burner wind box 128 at the same time.

  An after air nozzle 130 is installed above the burner. Usually, a part of the air supplied as the secondary and tertiary air of the burner branches after being branched into the after-air air 132 and is ejected from the after-air nozzle 130 to the furnace combustion space 118. A nose 134 is provided on the upper portion of the furnace rear wall 116. Due to the influence of the nose 134, the flow of the combustion gas around the after air nozzle 130 becomes asymmetric.

  23 is a cross-sectional view taken along the line F-F ′ in FIG. 22. A plurality of after air nozzles 130 are usually arranged at right angles to the flow of the combustion gas. In FIG. 23, there are an after air nozzle 130 disposed from the furnace side wall 136 and an after air nozzle 130 disposed from the center of the furnace. Due to the influence of the wall, the flow state and temperature of the combustion gas are different between the furnace side wall 136 side and the center side.

  Due to the influence of the nose 134 and the furnace side wall 136, the arranged after air nozzles 130 are placed under different flow and temperature environments. In order to bring the combustion conditions in the furnace including NOx and CO into the most desirable state, it is desirable that the conditions for ejecting air from the after air nozzle 130 can be optimized in accordance with the environment in which they are placed. .

  In the after air nozzle 130 of the present invention, the flow state of the contracted flow portion 24 provided in each after air nozzle 130 can be finely adjusted individually, so that the ejection of air from each after air nozzle 130 according to the environment in which it is placed Conditions can be kept optimal. According to the present invention, NOx and CO can be reduced at the same time only by contriving the after-air nozzle structure.

  The embodiments of the present invention described above are listed as follows.

  In the after-air nozzle used in the boiler for two-stage combustion, a flow-reducing section in which the outer diameter of the flow path decreases toward the air outlet of the outlet and a cross-sectional area of the flow path of the reduced-flow section are flown in the after-air nozzle. An after-air nozzle having means for changing without changing the road outer diameter.

  The after air nozzle has a reduced flow portion whose flow path outer diameter is reduced toward the air outlet of the outlet, and means for changing the flow path cross-sectional area of the reduced flow portion is configured to change the air flow in the after air nozzle. After air nozzle inside the road.

  The after air nozzle has a reduced flow portion whose flow path outer diameter decreases toward the air outlet of the outlet, and a member that defines a minimum flow area of the reduced flow portion is provided inside the after air nozzle. An after air nozzle having a structure capable of changing the cross-sectional area of the flow-reducing portion by moving a member that defines the minimum flow-path area of the flow-reducing portion.

  The after air nozzle has a reduced flow portion whose flow path outer diameter decreases toward the air outlet of the outlet, and a member that defines a minimum flow area of the reduced flow portion is provided inside the after air nozzle. An after-air nozzle having a structure in which a member defining the minimum flow path area of the contracted flow part can be replaced independently, and a cross-sectional area of the flow contracted part can be changed by replacing the member. .

  An after-air nozzle in which a member that defines the minimum flow path area of the contracted flow portion has a structure in which an outer diameter gradually decreases toward an air outlet of the outlet.

  The movement range of the member that defines the minimum flow path area of the contracted portion when the flow direction of the air flowing through the after air nozzle is used as a reference, the tip of the moving range is upstream of the starting position of the contracted portion An after-air nozzle having a structure starting from a location located at the end and ending at a location located downstream in the flow direction from the start position of the contracted flow portion.

  A furnace that burns fuel and air and generates steam by the thermal energy of the combustion gas, a burner that is provided upstream of the furnace in the gas flow direction, and burns the fuel under air-deficient conditions, and a gas flow direction of the furnace In a two-stage combustion boiler having an after-air nozzle that supplies air for completely combusting combustion gas, provided on the downstream side and downstream of the burner, an after-air nozzle adjustment device for use in combustion adjustment A two-stage combustion boiler in which an operation direction and an effect on combustion performance expected at that time are described in either the apparatus main body, the vicinity of the apparatus, or the instruction manual.

It is a longitudinal cross-sectional view of the after air nozzle which shows embodiment of this invention. It is a longitudinal cross-sectional view when the flow path area of the contraction part of the after air nozzle shown in FIG. 1 is made small. It is a longitudinal cross-sectional view when enlarging the flow path area of the constriction part of the after air nozzle shown in FIG. It is sectional drawing which follows the after air nozzle A-A 'line shown in FIG. It is sectional drawing which follows the after-air nozzle C-C 'line | wire of FIG. It is sectional drawing which follows the AA 'line of the after air nozzle of FIG. It is a longitudinal cross-sectional view of the after air nozzle explaining the modification of embodiment of this invention shown by FIG. It is a longitudinal cross-sectional view of the after air nozzle which shows Embodiment 2 of this invention. It is a longitudinal cross-sectional view of the after air nozzle which follows the DD 'line of FIG. It is a longitudinal cross-sectional view of the after air nozzle which shows the modification of embodiment of FIG. It is a longitudinal cross-sectional view of the after air nozzle which shows Embodiment 3 of this invention. It is the figure which looked at the adjustment apparatus of the after air nozzle shown in FIG. 11 from the outer side of a furnace. It is a longitudinal cross-sectional view of the after air nozzle which follows the EE 'line of FIG. It is a longitudinal cross-sectional view of the after air nozzle which shows Embodiment 4 of this invention. It is a longitudinal cross-sectional view when the flow-path area of the constriction part of the after air nozzle of embodiment shown in FIG. 14 is made small. It is a longitudinal cross-sectional view of the after air nozzle which shows Embodiment 5 of this invention. It is a longitudinal cross-sectional view of the after air nozzle which shows the modification of embodiment of this invention of FIG. It is a block diagram of the after-air nozzle (straight / revolving nozzle) of the comparison object used for verification of the effect of this invention. It is a block diagram of the after-air nozzle (straight forward nozzle 1) used as a comparison object used for verification of the effect of the present invention. It is a block diagram of the after-air nozzle (straight advance nozzle 2) of a comparison object used for verification of the effect of this invention. It is an experimental result which verified the effect of this invention. It is sectional drawing which shows the combustion gas flow direction of the furnace by embodiment of this invention. It is sectional drawing which follows the FF 'line | wire of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Windbox outer cylinder, 12 ... Windbox opening part, 14 ... Air flow, 16 ... Jet outlet, 18 ... Furnace combustion space, 20 ... Water pipe, 22 ... Shrinkage member, 24 ... Shrinkage part, 26 ... A member that defines the minimum flow path area of the contracted flow part, 28... A small flow path of the contracted flow part, 30. A support material of a member that defines the minimum flow path area of the contracted flow part, 32. 36 ... Wind box outer wall, 38 ... Guide roller, 40 ... Slide ring moving rod fixing mechanism, 42 ... Slide ring moving rod, 44 ... Handle, 46 ... Overheat prevention material, 48 ... Guide, 50, 52 ... Cooling air hole, 56 ... Cooling air guide plate, 65 ... Support material for overheating prevention material, 90 ... Detachable windbox outer plate, 25 ... Flow of cooling air, 31 ... Shrinkage nozzle damper, 98 ... Swirling blade, 58 ... Cooling air inlet 60 ... Guide sleeve for adjusting rejection air, 62 ... Slide ring inner cylinder, 64 ... Slide ring outer cylinder, 66 ... Cooling promotion plate, 68 ... Slide ring mover, 70 ... Rotating shaft with screw, 72 ... Rotating bearing, 74 ... Rotating disc 76 ... Rotating handle, 78 ... Belt or chain, 80 ... Rotating shaft, 84 ... Plate, 86a, 86b, 92a, 92b ... Bolt, 88 ... Removable inner cylinder, 91a to 91d ... Air hole, 94 ... Condensed nozzle 96 ... Linear nozzle, 100a to 100c ... Damper, 110 ... Furnace ceiling, 112 ... Hopper, 114 ... Furnace front wall, 116 ... Furnace rear wall, 118 ... Gas after combustion, 120 ... Burner, 122 ... Flame with insufficient air 124 ... Primary air and pulverized coal for burner, 126 ... Secondary and tertiary air for burner, 128 ... Wind box for burner, 130 ... After air nozzle, 132 After-air, 134 ... nose, 136 ... the furnace side wall.

Claims (5)

A wind box outer tube surrounding an outer peripheral portion of the after-air nozzle, and wind boxes opening the combustion air flows, and a contraction portion flow path outside diameter is reduced toward the air ejection port for supplying air to the boiler, the A flow path cross-sectional area changing device that changes the flow cross-sectional area of the contracted portion, and the flow path cross-sectional area changing device is provided inside the air flow path in the after air nozzle, A member that defines the minimum flow path area of the contracted flow portion is provided, and the member that defines the minimum flow path area is moved in the flow channel direction so that the flow path cross-sectional area of the contracted flow portion can be changed. And a slide member that adjusts the amount of combustion air flowing into the after-air nozzle from the window box opening is attached to the window box outer cylinder to keep the amount of air flowing from the window box opening constant. Two-stage after-air nozzle of the combustion boiler is characterized in that so as to vary the area of the windbox opening as. A member that defines the minimum flow path area of the contracted flow portion is provided inside the after air nozzle, and the member that defines the minimum flow path area of the contracted flow portion can be replaced independently. The after- air nozzle of the two-stage combustion boiler according to claim 1, wherein the afterflow nozzle has a structure capable of changing a flow path cross-sectional area of the contracted flow portion . The after-air nozzle according to claim 1, wherein the member that defines the minimum flow path area of the contracted flow portion has a structure in which an outer diameter gradually decreases toward an air outlet . The movement range of the member that defines the minimum flow path area of the contracted portion when the flow direction of the air flowing through the after air nozzle is used as a reference is such that the tip portion is upstream in the flow direction from the start position of the contracted portion. 2. The after air nozzle according to claim 1, wherein the after air nozzle starts from a location located at a position and ends at a location located downstream in the flow direction from the start position of the contraction portion . A furnace that burns fuel and air and generates steam by the thermal energy of the combustion gas, a burner that is provided upstream of the furnace in the gas flow direction, and burns the fuel under air-deficient conditions, and a gas flow direction of the furnace In the two-stage combustion boiler that has an after air nozzle that supplies air for completely burning the combustion gas, provided downstream and downstream of the burner,
A plurality of after-air nozzles installed in the furnace are a flow path toward a wind box outer cylinder surrounding an outer periphery of the after-air nozzle, a wind box opening into which combustion air flows, and an air outlet for supplying air to the boiler And a flow path cross-sectional area changing device that changes a flow path cross-sectional area of the flow reducing portion, and the flow path cross-sectional area changing device has a minimum flow area of the flow reducing portion. A member that defines the minimum flow area of the contracted portion is moved in the direction of the flow path so that the cross-sectional area of the contracted portion can be changed. The amount of air that flows through the window box opening by attaching a slide member that adjusts the amount of combustion air flowing into the after air nozzle from the window box opening. Two-stage combustion boiler, characterized in that so as to vary the area of the windbox opening so as to maintain constant.

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