JP4444791B2 - Fuel combustion air port, manufacturing method thereof and boiler - Google Patents

Description

  The present invention relates to a fuel combustion air port, a manufacturing method thereof, and a boiler.

  In combustion furnaces such as boilers, reduction of nitrogen oxide (NOx) concentration and reduction of unburned components are required, and a two-stage combustion method is applied to meet such demands.

  In the two-stage combustion method, an incomplete combustion region (region with a lot of combustible gas) that is less than the theoretical air ratio (theoretical fuel air amount) is formed in the combustion furnace by a burner, and an air port (after-air port) provided downstream of the burner ), A combustion system for supplying insufficient air to the combustible gas in the incomplete combustion region. This combustion method can achieve low NOx by suppressing a high temperature combustion region due to excessive oxygen. The theoretical air ratio means that the ratio between the burner air amount and the theoretical combustion air amount necessary for complete combustion is 1: 1.

  In the two-stage combustion, in order to reduce the unburned content, it is desired to promote the mixing of the combustible gas in the incomplete combustion region formed by the burner and the air supplied from the air port.

  As a measure for improvement, in Patent Document 1, a guide sleeve with a baffle is installed in an air port, and the flow of air (primary air) parallel to the center of the air port is spread as the air ejection direction and spreads around the air port. A flow (secondary air) is formed. In this method, the mixing of the combustion gas and air in the combustion furnace is promoted by expanding the entire jet.

  Patent Document 2 proposes a method of penetrating the jet to the inside of the combustion apparatus by reducing the air flow ejected from the air port. At the same time, this method has a structure that does not generate clinker.

  In these examples, the directionality of the air flow ejected from the air port is fixed.

Japanese Patent Laid-Open No. 2001-355832 (Claims, FIG. 2) Japanese Patent Laid-Open No. 10-122546 (Claims, FIG. 1)

  The positional relationship between the incomplete combustion region formed in the combustion furnace in the two-stage combustion method and the air port used as the after-air port varies depending on the form of the combustion furnace. Therefore, it is desired that the air ejection direction of the air port can be arbitrarily adjusted corresponding to the position of the incomplete combustion region.

  In response to the above requirements, the present invention changes the direction and mode of the air ejected from the after-air port in accordance with the position of the incomplete combustion region of the two-stage combustion method, thereby mixing the incomplete combustion region and the air. An apparatus that increases efficiency is provided.

  Moreover, the apparatus which can reduce the clinker adhesion of an air port and the temperature rise of an air port is also proposed.

  The basic configuration of the present invention is directed to the axial velocity component and the center of the air flow in the air port for supplying the insufficient combustion air to the incomplete combustion region formed by the burner in the furnace below the theoretical air ratio. A nozzle mechanism for ejecting combustion air containing a velocity component and a mechanism for changing the ratio of the velocity components are provided.

  For example, the air nozzle mechanism includes a primary nozzle that ejects primary air that travels straight in the axial direction of the air port, a secondary nozzle that ejects secondary air that travels with a swirling flow in the axial direction of the air port, and the primary A tertiary nozzle that blows out air from the outside of the nozzle toward the center as tertiary air. The mechanism for changing the ratio of the velocity components is constituted by a mechanism for changing the flow rate ratio of the primary air, the secondary air, and the tertiary air.

  The air port in the present invention is applicable not only to air but also to an air port that supplies air mixed with exhaust gas or water.

  The air port of the present invention is suitable for a two-stage combustion type after-air port, and is excellent in reducing unburned components. In particular, by injecting combustion-promoting air with an air flow in accordance with the position into an incomplete combustion area (a place where a large amount of combustible gas is gathered) in the furnace, it depends on the state of the combustion space. Therefore, it is possible to efficiently reduce the unburned content.

  Hereinafter, an air port of the present invention and a method of using the same will be described with reference to the drawings.

  First, a two-stage combustion boiler using the air port of the present invention will be described with reference to FIG.

  FIG. 1 shows the overall structure of the boiler.

  In the furnace 113 of the boiler, a plurality of burners 101 are opposed to each other at the lower part of the furnace wall, and a plurality of air ports 100 are arranged to face each other above the burner installation location. The burner 101 injects an air-fuel mixture having a theoretical air ratio or less (e.g., 0.8) into a flame region in the furnace to form an incomplete combustion region in the furnace. The air port 100 supplies combustion shortage air to the combustible gas in the incomplete combustion region to promote combustion.

  The fuel supplied to the burner 101 is coal, oil, gas, or the like. The total amount of air for combustion is managed by an air supply system, and the amount of air is distributed to the burner 101 and the air port 100. Specifically, the air supplied from the blower 114 branches to the air supply line 112 on the air port side and the air supply line 111 on the burner side via the air supply line 108, and the wind box of the air port 100 103 and the wind box 104 of the burner 101. The flow distribution is adjusted by the damper 110 on the air port side and the damper 109 on the burner side. The output of the blower 114 is controlled so that the total air flow rate becomes a value that specifies the oxygen concentration of the exhaust gas.

  The burner 101 is supplied with air below the theoretical air ratio from the air supply line 111, and is supplied with fuel from the fuel supply line 107. When supplying coal as fuel, it is good to carry coal by air current conveyance. Since the air-fuel mixture ejected from the burner 101 into the furnace (combustion space) 23 is less than the amount of air necessary for complete combustion, incomplete combustion occurs, and NOx can be reduced at this time. Due to incomplete combustion, a combustible gas stream 200 is formed downstream of the burner.

  Air entering the wind box 103 on the air port 100 side via the air supply line 112 is distributed to a primary nozzle, a secondary nozzle, and a tertiary nozzle of the air port 100 to be described later, and the flow of combustible gas in the furnace 23 (Incomplete combustion region) 200 is supplied. This air mixes with the combustible gas stream 200 and burns completely, becoming the combustion gas 106 and flowing to the outlet.

  Reference numeral 105 denotes a boiler water pipe disposed on the wall surface of the boiler.

Next, the aspect of the air port of the present invention applied to the boiler will be described by the following examples.
Example 1
2 is a cross-sectional view (A-A 'cross-sectional view of FIG. 4) showing an air port according to a first embodiment of the present invention, FIG. 3 is a partially omitted perspective view, and FIG. 4 is a view of the air port from inside the furnace. The figure is shown. FIG. 5 is a diagram showing the flow velocity at the air port outlet. 6, 7, and 8 are schematic diagrams showing the relationship between the air flow state in the furnace 23 and the incomplete combustion region (that is, a place where there is a lot of combustible gas).

  The air port 100 is disposed in the wind box 103. The air nozzle mechanism of the air port includes a primary nozzle 1, a secondary nozzle 2 that ejects swirling air along the outer periphery of the primary nozzle as secondary air, and the center line of the air port from the outside of the primary nozzle 1. And a tertiary nozzle 3 that ejects air flowing toward the center as tertiary air.

  The primary nozzle 1, the secondary nozzle 2, and the tertiary nozzle 3 have a coaxial nozzle structure, and the primary nozzle is located at the center, the secondary nozzle is located outside the center nozzle, and the tertiary nozzle is located outside the center nozzle.

  The primary nozzle 1 has a straight tubular shape, has an air ejection port 1A at the front end, and an air intake port 1B at the rear end. The primary damper 5 adjusts the primary air flow rate by adjusting the opening area of the air intake port 1B. The primary nozzle 1 ejects straight-flowing air parallel to the center line of the air port as primary air. The opening area of the air intake 1 </ b> B can be changed by sliding the primary damper 5 on the outer periphery of the primary nozzle 1.

  The secondary nozzle 2 has an annular air inlet 2B on the rear end side, and a two-air passage 2 'having an annular cross section is formed between the inner periphery of the secondary nozzle and the outer periphery of the primary nozzle. The secondary air 10 flowing in from the air inlet 2B is given a turning force by a secondary air register (deflecting plate) 7 and a secondary nozzle outlet (front end) with a swirling flow along the outer periphery of the primary nozzle 1. Spout from 2A. The opening area of the air intake port 2B of the secondary nozzle 2 can be changed by sliding the annular secondary damper 6 in the axial direction, thereby adjusting the secondary air flow rate. The secondary air register 7 is attached to the secondary air intake 2B via the support shaft 7A so that the deflection angle thereof can be changed, and a plurality of secondary air registers 7 are arranged in the circumferential direction of the secondary air intake 2B. By changing the deflection angle of the secondary air register 7, the turning force applied to the secondary air can be changed.

  The tertiary nozzle 3 has a conical front wall 301 and a conical rear wall 302 disposed opposite to the front wall, and the conical air of the tertiary nozzle is provided between the front wall and the rear wall. A flow path 3 'is formed. The air intake 3B of the tertiary nozzle 3 has an annular shape, and its opening area can be changed by sliding the annular tertiary damper 8 in the axial direction of the air port, thereby adjusting the tertiary air flow rate. Is done. The front wall 301 and the rear wall 302 are joined via a plurality of connecting plates 4 arranged in the air intake port 3B. The outlet 3A of the tertiary nozzle 3 is connected to the tip of the secondary nozzle 2, and the tertiary air 11 and the secondary air 10 are merged as shown by an arrow 12 to flow (spout) into the furnace. .

  Here, the secondary air 10 is parallel to the center line of the air port and is further given a turning force by the secondary air register 7. On the other hand, since the tertiary nozzle 3 is inclined with respect to the center direction of the air port (inward), it is suitable for forming a contracted flow in which the tertiary air 11 is concentrated in the center line direction of the air port. Structure. By changing the flow rates of the secondary air 10 and the tertiary air 11, it is possible to adjust the direction after the merging of the secondary air and the tertiary air.

  For example, if the flow rate of the tertiary air 11 is 0, the inward velocity component (velocity component toward the center of the air flow) of the air 12 after the secondary air 10 and the tertiary air 11 are merged is zero. Also. If the flow rate of the secondary air 10 is 0, the air 12 is jetted in the direction of the tertiary nozzle (inclined inward) due to the tertiary air occupying an increased inward velocity component. By adjusting the jet direction of the air 12, the unburned gas region with insufficient air and the air that are unevenly distributed in the furnace can be suitably mixed and the unburned portion can be reduced. Further, the mixing state can be adjusted by the strength of the swirling of the secondary air.

  In order to adjust the primary, secondary, and tertiary air flow ratios of the air ports, the primary damper 5, the secondary damper 6, and the tertiary damper 8 are used.

  FIG. 5 shows the flow velocity distribution of air at the outlet of the air port of this embodiment.

  FIG. 5A is an axial flow velocity (velocity component) of the air flow 12 injected from the air port. FIG. 2 (2) shows the flow velocity (velocity component) toward the center of the air flow 12 and is referred to herein as the central flow velocity. FIG. 3 (3) is the flow velocity (speed component) of the air flow 12 in the swirling direction, and is referred to as swirl flow velocity. 5 (1) to (3), the vertical axis represents the flow velocity, and the horizontal axis represents the distance from the center of the air port toward the outer diameter. The horizontal axis indicates the positions of the primary nozzle diameter and the secondary nozzle diameter.

  5 (1) to 5 (3), a solid line A is a case where primary air and secondary air are used and tertiary air is not used. Also, the turning of the secondary air register is set weak. In this case, the air flow 12 has a strong straight component (axial flow velocity) as a whole, and the air flow of the straight component is substantially uniformly distributed from the center of the air port 12 in the outer diameter direction.

  Such air travels straight from the air port and reaches the center of the furnace (combustion space) 23 as shown in FIG. Therefore, as shown in FIG. 6, when there is a large flow of combustible gas (incomplete combustion region) 34 between the opposed air ports at the center of the furnace 23, the air from the air port 12 is in that region. Can be supplied efficiently.

  5 (1) to (3), a broken line B is a case where the primary air flow rate is lowered and the secondary air flow rate is increased without using the tertiary air. Further, since the air turning force by the secondary air register 7 is set strongly, the straight component of the air flow 12 is weak and the turning force (turning flow velocity) is strong. As shown in FIG. 5 (3), the swirling flow velocity is concentrated near the outlet diameter of the secondary nozzle. In this case, as shown in FIG. 5 (1), the fast flow region of the axial flow velocity is concentrated between the primary nozzle outlet and the secondary nozzle outlet. In such a case, a flow having a large jet flow is formed as shown in FIG. In this case, as shown in FIG. 7, air is efficiently supplied to a place where there is a lot of combustible gas (incomplete combustion region) 34 in the vicinity of the center of the furnace 23 and at a position deviated left and right from the center connecting the opposed air ports 100. Can supply well.

  5 (1) to 5 (3), a thick line C represents a case where the primary air flow rate is decreased and the tertiary air flow rate is increased. Instead of having no turning speed, the central flow velocity (inward velocity component) is high. For this reason, gas can be entrained downstream from the air port 100 from its periphery. In such a case, as shown in FIG. 8, when there is an incomplete combustion region 34 at a location close to the wall between adjacent air ports 100, the combustible gas in that region 34 is converted into an air flow from the air port. Can be involved. Thereby, the mixing of combustible gas and air is promoted. The tertiary air 11 needs to be ejected at an inward angle suitable for entraining the combustible gas. Such an inward angle is preferably set in a range of approximately 20 ° to 45 °. If the angle is too small, the entrainment of gas is reduced and there is no effect. If the angle is too large, the turbulence becomes large, and the flow 12 of the secondary air and the tertiary air after merging cannot be stably formed.

  The place where there is a lot of combustible gas differs depending on the fuel ratio of coal, particle size, air ratio of burner, burner type, and furnace shape. Also, it differs in the center and outside in the furnace. As shown in A, B, and C of FIGS. 5 (1) to 5 (3), if the ratio of the air flow direction (speed component) can be changed, even if the place where there is a lot of combustible gas changes, the end-burning fuel content is always low. Can be kept in a state.

  When the flow ratio of primary, secondary, and tertiary air is changed, a place where air does not flow locally may be formed in the air port. In such a place, it is considered that the temperature rises due to radiant heat transfer from the combustion space. For this reason, it is preferable that the member of the air port in such a place can withstand high temperatures. For example, when the primary and secondary air is low, the temperature at the tip of the primary nozzle 1 becomes high. Therefore, materials that can withstand high temperatures are used here. Further, when the primary nozzle 1 is close to the combustion space 23, the viewing angle for viewing the flame is widened and the radiation intensity is increased. Therefore, the length of the tip of the primary nozzle is preferably shorter than the other nozzles.

  Some fuels contain ash, such as coal and heavy oil. In this case, if the tertiary air flow rate is increased and the air flow 12 is concentrated in the center direction, so-called contracted flow, the ash melted in the high-temperature combustion gas may adhere to the vicinity of the water pipe 14 at the outlet of the air port. . As ash deposits grow to form clinker, air flow may be hindered or water pipes may be damaged due to clinker dropping. In such a case, it is preferable that the flow rate of the tertiary air is reduced while the clinker is small, the flow rate of the secondary air is increased, and the temperature of the clinker is lowered, thereby generating thermal stress and peeling. It is easy to operate by checking whether the clinker is growing with a sensor and automatically increasing the flow rate of the secondary air if it is growing. As such a sensor, it is conceivable to use an optical sensor that detects that the field of view is limited as the clinker grows.

  Many of the conventional air ports are composed of only the primary nozzle 1 and the secondary nozzle 2, and the flow rate ratio between the primary nozzle 1 and the secondary nozzle 2 is fixed.

The process of converting such an existing air port product to the air port of the present invention is simple. Three examples of air port manufacturing methods with such modifications are listed.
(1) Cut off the tip of the secondary nozzle 2. Next, the secondary nozzle is welded to the outlet side of the tertiary nozzle 3 prepared in advance.
(2) Remove the secondary nozzle of the existing product. The component in which the secondary nozzle and the tertiary nozzle used in the present invention are integrated is welded to the existing primary nozzle from which the secondary nozzle is removed.
(3) Remove all nozzles from the air port of the existing product, weld new 1, 2 and 3 nozzles, and weld to the wall of the windbox.
(Example 2)
9 and 10 are cross-sectional views showing a second embodiment of the air port 100 according to the present invention.

  The difference from the first embodiment is that a movable sleeve 15 is provided between the outer periphery of the primary nozzle 1 and the inner periphery of the secondary nozzle 2 and is movable in the axial direction by operating the handle 21 from the outside. A movable sleeve 16 is provided so as to be movable integrally with the movable sleeve 15. That is, the movable sleeve has a double structure.

  The movable sleeves 15 and 16 are connected to each other via a connecting member 18 and are movable in the axial direction via a guide roller 17. The movable sleeve 15 is guided by the inner circumference of the secondary nozzle 2 and is movable in the axial direction, while the movable sleeve 16 is guided by the outer circumference of the primary nozzle 1 and is movable.

  Since the movable sleeve 15 becomes a part of the wall surface of the secondary nozzle 2 and the movable sleeve 16 becomes a part of the wall surface of the primary nozzle 1, it has a function of adjusting the length of the nozzle. Sometimes called. The guide roller 17 is provided in any of the movable sleeves (movable nozzles) 15 and 16, or the primary nozzle 1 and the secondary nozzle 2, and makes the movement of the movable sleeve smooth.

  For example, when the flow rate of the tertiary air 11 is increased by the tertiary damper 8, the movable nozzle 15 is moved to the position shown in FIG. 9 (position where the outlet area of the tertiary nozzle 3 is increased).

  The secondary damper 8 is throttled to reduce the flow rate of the tertiary air 11, while the secondary damper 6 enlarges the secondary air intake 2 </ b> B, increases the secondary air 10, and increases the swirling strength of the secondary register 7. Then, air may enter the duct of the tertiary nozzle 3. In addition, the swirl flow may not be stably maintained. In order to eliminate such a problem, in this embodiment, as shown in FIG. 10, the movable nozzle 15 is moved to the inside of the furnace so that the tertiary nozzle outlet 3 </ b> A is closed with the movable nozzle 15. Here, when the tertiary air flow rate is zero, the tertiary nozzle outlet 3A is completely blocked, and when the tertiary air flow rate is small, most of the tertiary nozzle outlet 3A is blocked. Keep it somewhat open.

  In the state shown in FIG. 9, that is, when the amount of tertiary air is large and the flow rate of primary and secondary air is small, the temperature of the tip of the primary nozzle 1 may be high. Therefore, the primary nozzle is shorter than in the first embodiment. By the way, if the primary nozzle 1 is short when the tertiary air 11 is not flowed, the primary and secondary air may be mixed in the air port without any consideration. However, in this embodiment, in such a case, the movable sleeve (nozzle adjustment member) 16 moves to the vicinity of the outlet of the air port 12 as shown in FIG. 8, and this functions as an extension wall surface of the primary nozzle. Mixing of primary and secondary air in the air port can be prevented.

  In order to move the nozzle adjustment members 15, 16 from the outside of the window box outer wall 13, the operation handle 21 is connected to one of the nozzle adjustment members via the rod 20. Only one of the nozzle adjustment members 15 and 16 may be adopted as necessary.

  Since the movable sleeve (movable nozzle) moves close to the combustion space, the temperature tends to increase. For this reason, there is a possibility of movable deformation and burning. In such a case, it is preferable to install the take-out port 27 so that the movable sleeves 15 and 16 can be easily replaced and to pull out the movable nozzle. The take-out port 27 is provided in the rear wall 202 of the secondary nozzle 2 and is blocked by the blind plate 27A except for replacement of the movable nozzle. In the case of replacement, if the primary damper 5 gets in the way, the damper 5 may be removed.

  FIG. 11 is a view of the rear wall 202 of the secondary nozzle 2 and the blind plate 27 as viewed from the X direction of FIG. As shown in the figure, the blind plate 27A is formed by dividing an annular one into a plurality (for example, four divisions) in the circumferential direction. In this example, the circumferential ends 203 of each dividing element of the blind plate 27A are raised vertically from the plate surface, the end 203 is aligned with the end 203 of the adjacent dividing element, and the screw 204 is tightened to tighten each division. Combining elements.

FIG. 12 shows another embodiment of the blind plate 27A. Also in this example, the blind plate 27 is divided into a plurality. These dividing elements are directly attached to the rear wall 202 of the secondary nozzle 2 via 204.
(Example 3)
FIG. 13 is a cross-sectional view showing a third embodiment of the air port according to the present invention.

  In this example, movable sleeves (movable nozzles: nozzle adjusting members) 15 and 16 are provided, but differ from the second embodiment in the following points. In this example, among the conical front walls 301 and 302 constituting the tertiary nozzle 3, the rear wall 302 is slidable in the axial direction. The opening area of the outlet 3A of the tertiary nozzle can be changed by sliding the rear wall 302. In this example, the rear wall 302 is integrally coupled to the movable sleeve 15 of the secondary nozzle 2, and the rear wall 302 is also moved simultaneously by the moving operation of the movable sleeve 15. The front wall 301 is fixedly supported in the wind box 13.

  Also in this embodiment, when the flow rate of the tertiary air 11 is reduced (including zero flow rate) and the secondary air flow rate is increased, the movable sleeve 15 is moved closer to the furnace 23. By this sleeve movement, the rear wall 302 moves so as to narrow the outlet 3A of the tertiary nozzle. Therefore, it is possible to prevent secondary air (swirl air) from flowing into the tertiary nozzle 3 side. In this case, since there is nothing that causes the disturbance of the duct 3 'of the tertiary nozzle, the pressure loss can be reduced. Further, since the tertiary air 11 always flows along the wall surface, heat transfer can be promoted as a whole.

The movable sleeve 15 and the rear wall 302 of the tertiary nozzle are connected to each other via the heat transfer plate 26 that is arranged radially. If either secondary or tertiary air is flowing, the movable sleeve 15 and the rear wall 302 of the tertiary nozzle are cooled. Further, by using a large number of members 18 that connect the movable sleeve (secondary nozzle element) 15 and the movable sleeve (primary nozzle element) 16, heat transfer between the movable sleeves is improved and the temperature of the movable sleeve 16 is also reduced. can do.
Example 4
FIG. 14 is a cross-sectional view showing a fourth embodiment of the air port according to the present invention.

  In the present embodiment, in addition to the first embodiment, an air register 22 is provided in the air intake port 3B of the tertiary nozzle for applying a turning force to the tertiary air. The structure of the air register 22 is the same as that of the secondary air register 7 described above. The air register 22 is supported via the support shaft 22B so that the deflection angle can be changed, and a plurality of air registers 22 are arranged in the circumferential direction of the air intake port 3B. It is installed.

  By making the tertiary air 11 a contracted flow with a swirl force, the flammable gas 34 near the air port is entrained, and at the same time, the swirl force expands the jet, and between the air ports near the center of the furnace 23 It is possible to supply the air 12 ejected from the air port to the combustible gas 34 in the air. This state is shown in FIG.

  A straight pipe 110 parallel to the axis of the air port is formed at the outlet 110 of the air port 100. The straight pipe portion 110 has a function of rectifying the air flow in the vicinity of the water pipe 14 connection portion at the air port outlet. If the connection portion between the tertiary nozzle outer wall 301 and the water pipe 14 has a steep angle, stress may increase at the connection portion, or the flow may suddenly peel off and cause turbulence. In such a case, the above problem can be avoided by adopting this shape.

Further, in the present embodiment, the sectional area of the place near the tertiary air intake 3B is increased by changing the inclination angle (taper angle) of the front wall 301 and the rear wall 302 of the tertiary nozzle. By doing in this way, the pressure loss of the tertiary air intake 3B can be reduced, and the contraction effect can be improved.
(Example 5)
FIG. 16 is a sectional view showing Embodiment 5 of the air port according to the present invention.

  In this embodiment, a structure for cooling the primary nozzle 1 is added in addition to the mechanism for changing the flow ratio of primary air, secondary air, and tertiary air, as in the above-described embodiments.

  The outer periphery close to the outlet side of the primary nozzle (primary duct) 1 and the inner periphery close to the outlet side of the secondary nozzle (secondary duct) 2 are connected by a plurality of radially arranged heat transfer plates 32, and this heat transfer The heat of the primary nozzle is transmitted to the secondary nozzle through the plate 32. In addition, the heat transfer plate 26 transfers the heat of the secondary nozzle 2 to the inner wall 301 of the tertiary nozzle inner wall 3.

  According to such a configuration, all of the nozzles can be cooled if any of the primary, secondary, and tertiary air flows.

Further, in the present embodiment, the primary cooling nozzle 36 is installed in a part of the duct of the primary nozzle 1 so that the primary nozzle 1 can be cooled even if the flow rate of the primary air is small. For example, the primary cooling nozzle 36 has a duct in which the cooling air intake 36 </ b> A is provided adjacent to the primary air intake 1 </ b> B and the cooling air flows along the inner wall of the duct of the primary nozzle 1. When the primary air flow rate is reduced by restricting the primary damper 24, air flows only to the primary cooling nozzle. The cooling effect of the primary nozzle is improved by ejecting a small amount of air in the vicinity of the primary nozzle 1 at high speed.
(Example 6)
17 and 18 are sectional views showing Embodiment 6 of the air port according to the present invention.

  In this embodiment, the duct of the secondary nozzle 2 is divided into a duct 230 on the side having the tertiary nozzle 3 and a duct 231 on the side having the air intake 2B, of which the former duct 230 is surrounded by the latter duct 231. It is fitted so that it can rotate in the direction.

  A gear 28 that is an element of the secondary nozzle rotating mechanism is provided on the outer periphery of the duct 230, and the gear 28 meshes with the power transmission gear 29. When the rotary handle 31 provided on the windbox outer wall 13 is operated, the duct 230 rotates about the axis via the universal joint 30, the power transmission gear 29, and the gear 28 that are power transmission elements. The duct 230 is provided with symmetrical cutouts 230A and 230B at a tip portion 230 ′ thereof (see FIG. 18), and has a structure in which the outlet 3A of the tertiary nozzle 3 is partially blocked by a wall surface other than the cutouts. It has become. The tertiary air 11 is ejected through the notches 230A and 230B. Therefore, the tertiary air ejection position of the tertiary nozzle 3 can be changed by rotating the duct 230 of the secondary nozzle. In this embodiment, the duct 230 and the rear wall 302 of the tertiary nozzle are joined together by welding or the like so that the rear wall 302 rotates together with the duct 230.

According to the present embodiment, by setting the duct 320 of the tertiary nozzle at the position shown in FIG. 18, it is possible to reduce the flow only to the left and right of the tertiary nozzle 3, so that only the left and right combustible gases are involved. it can. In this case, since the combustible gas is not sucked in from the upper and lower sides of the tertiary nozzle, the energy of suction can be saved. Further, when it is desired to suck in only from above and below, the duct 320 may be rotated 90 degrees from the position shown in FIG.
(Example 7)
FIG. 19 is a cross-sectional view showing a seventh embodiment of the air port according to the present invention, and FIG. 20 is a view of the air port as viewed from the inside of the furnace.

  This embodiment is different from the other embodiments in that the installation position of the tertiary nozzle 3 is completely outside the secondary nozzle 2. Both the tertiary nozzle outlet 3A and the secondary nozzle outlet 2A face the furnace 23. That is, in the embodiment described so far, the tertiary air 11 ejected from the tertiary nozzle outlet 3A merged in the air port 100 with the air 10 ejected from the secondary nozzle outlet 2A. The tertiary air 11 and the secondary air 10 are structured to merge in the furnace 12.

  Even with such a structure, it is possible to obtain the same effects as in the previous embodiments. Also. With this method, even if the swirl of the secondary air is strengthened, the possibility of entering the tertiary nozzle is small.

However, the inner wall of the tertiary nozzle can be seen from the combustion space, and the temperature here can be considered to rise due to radiant heat. For this reason, it is necessary to ensure that the flow rate of the tertiary air is always assured as necessary to suppress the temperature rise of the tertiary nozzle. Alternatively, if the heat transfer plate 26 is installed between the secondary nozzle and the tertiary nozzle so that the secondary air flows, the temperature of the inner wall of the tertiary nozzle can be lowered.
(Example 8)
FIG. 21 is a front view of an air port according to an eighth embodiment of the present invention as viewed from the air port outlet side. The cross-sectional view is the same as FIG. The difference from the sixth embodiment is that the tertiary nozzle 3 is not conical and is arranged above and below the secondary nozzle 2. That is, the tertiary nozzle 3 is composed of two separate type nozzles. In this embodiment, the tertiary air is ejected from two places above and below the secondary air, and the secondary air and the tertiary air merge in the furnace. Even with such a structure, it is possible to adjust the straight flow and the contraction flow.
Example 9
FIG. 22 is a sectional view showing Embodiment 9 of the air port according to the present invention. In this embodiment, in addition to the structure of the first embodiment, a primary air blocking plate 37 is installed in the primary nozzle 1. Further, this can be moved in the axial direction in the primary nozzle via the rod 210 by the handle 21.

  When the primary air shielding plate 37 is retracted until it comes into contact with the outer wall 13 of the windbox, the air port 100 has a structure similar to that of the first embodiment.

When the primary air shielding plate 37 is moved to the outlet 1A of the primary nozzle 1, a small amount of primary air can be ejected from between the primary air shielding plate 37 and the inner wall of the primary air nozzle, and the primary nozzle is cooled. it can. There is a possibility that the temperature of the primary air shielding plate 37 is increased by the irradiation. Therefore, it is preferable to use materials that can withstand high temperatures such as refractory bricks and ceramics. Further, as shown in FIG. 22, if the hole 37 </ b> A through which primary air flows is provided in the shielding plate 37, the shielding plate 37 can be cooled. Further, the plate 37 can also serve to prevent secondary and tertiary air and combustion gas from the furnace 23 from entering the primary air.
(Example 10)
FIG. 23 is a sectional view showing Embodiment 10 of the air port according to the present invention.

The difference from the embodiment described so far is that there is no primary nozzle in this embodiment. The secondary nozzle 2 functions as a combined nozzle of the primary nozzle and the secondary nozzle of the first embodiment. The register 7 is not essential, but can be used to optimize the flow state of the combustion space by swirling. In this example, the case where there is no primary nozzle of FIG. 1 is shown, but the same structure can be obtained even when the primary nozzle is omitted in the air port of FIG.
(Example 11)
FIG. 24 is a sectional view showing Example 11 of the air port according to the present invention.

  In this embodiment, there is no primary nozzle as in the embodiments described so far, and it consists of a secondary nozzle 2 and a tertiary nozzle 3. Strictly speaking, the first nozzle 2 and the second nozzle 3 are used, and the air of the first nozzle 2 is swirled and ejected in the direction of the nozzle axis, and the second nozzle 3 is contracted. To join the swirling flow of the first nozzle 2. Here, like the other embodiments, the nozzle 2 is referred to as a secondary nozzle, and the nozzle 3 is referred to as a tertiary nozzle. A spindle-shaped object 38 is contained in the secondary nozzle 2 and can move in the axial direction (front and rear) of the nozzle 2. The secondary nozzle 2 has a tapered shape in which the passage cross-sectional area gradually narrows toward the outlet 2A. Accordingly, when the spindle-shaped object 38 is moved (advanced) toward the furnace (combustion space) 23, the flow path area is reduced and the secondary air does not flow. When the spindle-shaped object (spindle body) 38 is moved (retracted) in the opposite direction, the flow path area is increased and the secondary air can easily flow. Thus, since the spindle-shaped object 38 has a function of adjusting the flow rate, the same effect can be obtained without the secondary damper 6. Also, the temperature of spindle-shaped objects can rise. It is desirable to make the material resistant to high temperatures.

The figure which shows the whole structure of the boiler of the two-stage combustion system used as the application object of this invention. Sectional drawing which showed Example 1 of the air port by this invention (AA sectional drawing of FIG. 4). FIG. The figure which looked at the air port from the inside of a furnace. The figure which shows the flow-velocity distribution of the exit of the said air port. The schematic diagram which shows the relationship between the flow state of the air in a furnace, and an incomplete combustion area | region. The schematic diagram which shows the relationship between the flow state of the air in a furnace, and an incomplete combustion area | region. The schematic diagram which shows the relationship between the flow state of the air in a furnace, and an incomplete combustion area | region. Sectional drawing which shows Example 2 of this invention. Sectional drawing which shows the state from which FIG. 9 of Example 2 changed operation | movement. The figure which looked at the rear wall and blind board of the secondary nozzle from the X direction of FIG. The figure which shows another aspect of the said blind board. Sectional drawing which showed Example 3 of the air port by this invention. Sectional drawing which showed Example 4 of the air port by this invention. The figure which shows the relationship between the air ejection from the air port in Example 4, and the incomplete combustion area | region in a furnace. Sectional drawing which showed Example 5 of the air port by this invention. Sectional drawing which showed Example 6 of the air port by this invention. FIG. 18 is a cross-sectional view taken along line AA ′ of FIG. 17. Sectional drawing which showed Example 7 of the air port by this invention. The figure which looked at the air port of FIG. 19 from the inside of a furnace. Sectional drawing which showed Example 8 of the air port by this invention. Sectional drawing which showed Example 9 of the air port by this invention. Sectional drawing which showed Example 10 of the air port by this invention. Sectional drawing which showed Example 11 of the air port by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Primary nozzle 2, 2 ... Secondary nozzle, 3 ... Tertiary nozzle, 5, 6, 8 ... Variable speed ratio ratio mechanism (primary damper, secondary damper, tertiary damper), 7 ... 2 Secondary air register, 9 ... primary air flow, 10 ... secondary air flow, 11 ... tertiary air flow, 12 ... secondary air flow after merging, 15, 16 ... movable sleeve (nozzle adjustment member) , 23 ... in the furnace, 34 ... incomplete combustion region (a place where there is a lot of combustible gas), 35 ... flow of gas entrainment, 36 ... primary cooling nozzle, 37 ... primary air blocking plate, 38 ... spindle-shaped object.

Claims (11)

In the air port that supplies the insufficient combustion air to the incomplete combustion area below the theoretical air ratio formed by the burner in the furnace,
A nozzle mechanism for ejecting combustion air containing an axial velocity component and a velocity component toward the center of the air flow, and a mechanism for changing the ratio of the velocity components,
The nozzle mechanism includes a primary nozzle that ejects primary air that travels straight in the axial direction of the air port, a secondary nozzle that ejects secondary air that travels with a swirling flow in the axial direction of the air port, and the primary nozzle A tertiary nozzle that ejects air from the outside toward the center as tertiary air;
The mechanism for changing the ratio of the velocity components is constituted by a mechanism for changing the flow rate ratio of the primary air, secondary air, and tertiary air,
The primary nozzle, the secondary nozzle, and the tertiary nozzle have a coaxial nozzle structure, and the outlet of the tertiary nozzle is connected to the tip of the secondary nozzle to join the tertiary air and the secondary air. To blow out ,
A sleeve capable of moving in the axial direction of the secondary nozzle is provided along the inner periphery of the secondary nozzle, and the sleeve can change the cross-sectional area of at least one of the secondary nozzle and the tertiary nozzle. An air port for fuel combustion characterized by that.   2. The tertiary nozzle according to claim 1, wherein the tertiary nozzle has a conical front wall and a conical rear wall disposed opposite to the front wall, and the tertiary nozzle is disposed between the conical front wall and the rear wall. An air port for fuel combustion in which an air flow path of a nozzle is formed, the rear wall is slidable in an axial direction, and the flow path cross-sectional area of the tertiary nozzle can be changed by sliding of the rear wall.   2. The fuel combustion air port according to claim 1, wherein a rear wall of the tertiary nozzle is provided at a tip of a movable sleeve that is guided by the secondary nozzle and moves in the axial direction. 3.   2. The fuel combustion air port according to claim 1, wherein the air ejected from the air nozzle mechanism is air mixed with exhaust gas or water vapor.   2. The fuel combustion air port according to claim 1, wherein the tertiary nozzle is configured to eject air accompanied by a swirling flow in addition to the contracted flow from the outside toward the center. 3.   2. The fuel combustion air port according to claim 1, wherein the secondary nozzle and the tertiary nozzle are connected by a heat transfer promotion plate to promote heat conduction.   2. The fuel combustion air port according to claim 1, wherein the primary nozzle and the secondary nozzle are connected to the tip of the primary nozzle by a heat transfer promotion plate to promote heat conduction.   2. The rotary nozzle according to claim 1, wherein a part of the secondary nozzle is rotatable about an axis, and the rotatable nozzle is provided with a symmetrical notch. An air port for fuel combustion in which an outlet is partially blocked and the notch functions as an outlet opening of the tertiary nozzle. In the manufacturing method of the air port which has a nozzle structure according to claim 1,
A step of cutting a tip portion of a secondary nozzle in an existing air port product composed only of the primary nozzle and the secondary nozzle, and the tertiary nozzle previously prepared in the cut-out portion of the secondary nozzle And a step of welding the tip of the air port. In the manufacturing method of the air port which has a nozzle structure according to claim 1,
The step of removing the secondary nozzle in the existing air port product composed only of the primary nozzle and the secondary nozzle, and the part in which the secondary nozzle and the tertiary nozzle are integrated in advance are combined with the secondary nozzle. And a step of welding to the removed primary nozzle. A burner that forms an incomplete combustion area in the combustion furnace that is less than the stoichiometric air ratio, an air port that supplies insufficient air to the combustible gas in the incomplete combustion area, and a total amount of air for combustion is controlled; In a two-stage combustion boiler provided with an air supply line that distributes the amount of air to the burner and the air port,
An air port for fuel combustion, wherein the air port is constituted by the air port according to claim 1.

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