JP7492420B2 - Combustion burners and boilers - Google Patents

Description

The present disclosure relates to a combustion burner and a boiler equipped with the combustion burner.

A coal-fired boiler has a furnace with a combustion gas flow path formed inside, and multiple combustion burners are arranged in multiple stages vertically on the furnace wall. The combustion burners are equipped with a fuel nozzle to which a mixture of pulverized coal made from pulverized coal and primary air is supplied, and a combustion air nozzle that ejects combustion air from the outside of the combustion burner. This mixture with a high concentration of pulverized coal and the combustion air are blown into the furnace to form a flame, and water flowing through water pipes installed in the furnace wall and flue is converted into steam.

A known combustion burner for burning pulverized coal fuel is one that has a flame holder called a splitter installed inside the fuel nozzle. The flame holder is intended to hold the ignition position or hold the flame inside the fuel nozzle, which has a small amount of air, by forming a recirculation area of the mixture downstream of the splitter (hereinafter, this is also referred to as "internal ignition" or "internal flame holding"). At the same time, low-NOx combustion is achieved by performing reducing combustion under an air shortage. This reduces the high-temperature, high-oxygen area formed by ignition or flame holding that progresses in a high-temperature state with a high oxygen concentration on the outer periphery of the flame (hereinafter, this is also referred to as "external ignition" or "external flame holding"), making it possible to reduce NOx on the outer periphery of the flame.

Patent Document 1 discloses a configuration in which, in a combustion burner installed in a coal-fired boiler, multiple splitter-shaped flame holders are arranged inside a fuel nozzle, and adjacent flame holders are given one or both of the roles of flame holding and guiding the fuel gas to the flame holder, thereby improving the internal flame holding performance.

Patent No. 6408134

The combustion burner disclosed in Patent Document 1 has inclined surfaces for forming a recirculation region on both of the mutually facing surfaces of adjacent flame stabilizers, so that the recirculation regions of the mixture formed by the adjacent flame stabilizers may interfere with each other. When the recirculation regions interfere with each other, the low flow velocity region of the mixture formed in the recirculation region shrinks, and there is a risk that the ignition performance or flame stability performance of the flame stabilizer may decrease. In addition, as the low flow velocity region shrinks, the contact area between the NOx generated in the high temperature, high oxygen region on the outer periphery of the flame and the unburned fuel, which is a reducing material, becomes smaller, which makes it difficult for the reduction reaction to proceed, and also causes the problem of an increase in the amount of NOx generated on the outer periphery of the flame.

This disclosure was made in consideration of the above-mentioned problems, and aims to suppress a decrease in the ignition or flame-holding performance of the flame holder by eliminating interference between the recirculation regions of the mixture formed by adjacent flame holders.

In order to achieve the above object, the combustion burner according to the present disclosure comprises a fuel nozzle that ejects a fuel gas mixture of fuel and air, a combustion air nozzle that ejects combustion air from the outside of the fuel nozzle, a first member that is disposed inside the fuel nozzle and has a first inclined surface that is inclined with respect to the flow of the fuel gas and a first inclined end where the inclination of the first inclined surface ends, and a second member that is disposed downstream of the flow of the fuel gas from the first inclined surface and has a second inclined surface that is inclined with respect to the flow of the fuel gas and a second inclined end where the inclination of the second inclined surface ends, the first member and the second member are disposed adjacent to each other, and the first inclined surface or the second inclined surface is formed only on either the surface of the first member facing the second member or the surface of the second member facing the first member.

In this specification, the "first inclined end end" and the "second inclined end end" refer to the end where the fuel gas flowing along the first inclined surface or the second inclined surface starts to separate. For example, they refer to a corner where an inclined surface forming a triangular cross section ends, or the end of a plate where an inclined surface formed by bending a plate ends. In this specification, fuel gas mixed with fuel (e.g., pulverized coal) and air is also referred to as a "mixed gas," and the flow of the mixed gas is also referred to as a "mixed gas flow."

The boiler according to the present disclosure also includes a furnace having a combustion gas flow path formed therein, a heat transfer tube facing the combustion gas flow path, and the above-mentioned combustion burner provided in the furnace.

The combustion burner and boiler according to the present disclosure can suppress interference between the recirculation regions of the mixed air flow formed in the first member and the second member, thereby suppressing a decrease in the ignition performance or flame-holding performance of the mixed air flow at the first or second tilt end, and suppressing the generation of NOx on the outer periphery of the flame. Furthermore, it becomes easier to insert a poking rod between the first and second members, making it easier to remove ash that has accumulated near the opening of the fuel nozzle.

FIG. 2 is a front view of a combustion burner according to an embodiment. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 2 is a front view of a combustion burner according to an embodiment. FIG. 4 is a cross-sectional view taken along line B-B in FIG. FIG. 2 is a front view of a combustion burner according to an embodiment. FIG. 6 is a cross-sectional view taken along line CC in FIG. 5 . FIG. 4 is a front view of a combustion burner according to a comparative example. FIG. 8 is a cross-sectional view taken along line D-D in FIG. 7. 1 is a schematic configuration diagram of a coal-fired boiler according to one embodiment. FIG. FIG. 2 is a plan view showing the arrangement of combustion burners mounted on a coal-fired boiler.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of components described in these embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.
For example, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," not only express such a configuration strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only represent rectangular shapes or cylindrical shapes in the strict geometric sense, but also represent shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained.
On the other hand, the expressions "comprise,""include,""have,""includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

1 to 6 show a combustion burner 50 (50A, 50B, 50C) according to some embodiments. FIG. 1 is a front view of the combustion burner 50 (50A), and FIG. 2 is a cross-sectional view of the combustion burner 50 (50A) (cross-sectional view along line A-A in FIG. 1). FIG. 3 is a front view of the combustion burner 50 (50B), and FIG. 4 is a cross-sectional view of the combustion burner 50 (50B) (cross-sectional view along line B-B in FIG. 3). FIG. 5 is a front view of the combustion burner 50 (50C), and FIG. 6 is a cross-sectional view of the combustion burner 50 (50C) (cross-sectional view along line C-C in FIG. 5). FIG. 9 is a schematic diagram of a coal-fired boiler 10 according to one embodiment, and FIG. 10 is a plan view showing the arrangement of the combustion burner 50 provided in the coal-fired boiler 10.
Each of the combustion burners 50 (50A to 50C) is attached to, for example, the furnace wall of the coal-fired boiler 10 shown in FIG.

As shown in FIG. 9, the coal-fired boiler 10 uses pulverized coal as pulverized fuel and is equipped with a furnace 12 having a combustion gas flow path Fc formed therein. The furnace 12 is provided with a heat transfer tube facing the combustion gas flow path Fc. The pulverized coal is burned by a combustion burner 50 provided in the furnace 12, and the water flowing in the heat transfer tube is converted into steam by the combustion gas generated by this combustion and supplied to the intended use.

The coal-fired boiler 10 has a combustion device 14 having one of the combustion burners 50 (50A to 50C) and a flue 16, and the furnace wall that constitutes the furnace 12 is composed of heat transfer tubes. The combustion device 14 is provided at the bottom of the furnace wall and has multiple combustion burners 50 attached to the furnace wall. For example, in the exemplary configuration shown in FIG. 10, the multiple combustion burners 50 are arranged in five stages (five sets) in the vertical direction, with four burners evenly spaced around the circumference of the furnace 12 as one set. Each combustion burner 50 is connected to a plurality of mills (pulverizers) 20 via a pulverized coal supply pipe 18, and pulverized coal pulverized to a predetermined size by the mills 20 is supplied to each combustion burner 50 together with conveying air (primary air).

The wind box 22 is provided at the mounting position of the combustion burner 50. One end of the air duct 24 is connected to the wind box 22, and the other end of the air duct 24 is attached to the blower 26. Furthermore, an additional air nozzle 28 is provided above the furnace wall on which the combustion burner 50 is mounted, and a branch duct 30 branched from the air duct 24 is connected to the additional air nozzle 28. The combustion air (secondary air) sent by the blower 26 is supplied to each combustion burner 50 via the air duct 24 and the wind box 22, and is supplied to the additional air nozzle 28 via the branch duct 30. The coal-fired boiler 10 shown in FIG. 9 has an additional air nozzle, but the combustion burner 50 can also be applied to a boiler that does not have an additional air nozzle.

The above-mentioned conveying air (primary air) is the amount of air required to convey the pulverized coal fuel, and so the amount of air is determined by the mill 20 that crushes the coal into pulverized coal. The above-mentioned secondary air is the amount of air required to form the entire flame in the furnace 12. Therefore, the amount of secondary air is approximately 1 to 1.2 times the total amount of air required to burn the pulverized coal minus the amount of primary air.

The flue 16 is connected to the top of the furnace 12, and the flue 16 is provided with superheaters 34, 36, 38, reheaters 40, 42, and economizers 44, 46 for recovering heat from the exhaust gas, and heat exchange is performed between the combustion exhaust gas and the water flowing through the heat transfer tubes that constitute these devices. A gas duct 32 is connected to the downstream side of the flue 16, through which the exhaust gas after heat exchange is discharged. An air heater 48 is provided between the gas duct 32 and the air duct 24, and heat exchange is performed between the combustion air flowing through the air duct 24 and the exhaust gas flowing through the gas duct 32. This allows the combustion air to be supplied to the combustion burner 50 to be preheated. The gas duct 32 is provided with a denitration device, an electric dust collector, an induced draft fan, a desulfurization device, etc., not shown, and a chimney is provided at the downstream end.

The combustion device 14 will be described below by taking as an example one of the combustion burner sets provided in multiple stages in the vertical direction of the furnace 12. In the exemplary embodiment shown in FIG. 10, combustion burners 50a, 50b, 50c, and 50d are provided on the four walls of the furnace 12. Each of these combustion burners is connected to one of the branch pipes 18a, 18b, 18c, and 18d branched from the pulverized coal supply pipe 18, and to one of the branch pipes 24a, 24b, 24c, and 24d branched from the air duct 24. Therefore, a pulverized coal mixture (fuel gas) in which pulverized coal and conveying air are mixed is blown into each combustion burner 50a to 50d, and combustion air (secondary air) is blown outside the pulverized coal mixture. Ignition of this pulverized coal mixture forms four flames F1, F2, F3, and F4, which form a swirling flame flow C that swirls counterclockwise when viewed from above the furnace 12.

The pulverized coal mixture and combustion air (secondary air) are blown into the combustion area X shown in FIG. 9 by each combustion burner 50a-50d, forming a flame swirl C in the combustion area X. This flame swirl C rises while swirling and reaches the reduction area Y. In the combustion area X, the air supply amount is set to less than the theoretical air amount relative to the pulverized coal supply amount, creating a reducing atmosphere. NOx generated by the combustion of the pulverized coal is reduced in this reducing atmosphere, and then additional air (additional air) is blown from the additional air nozzle 28 above the reduction area Y, completing the oxidation combustion of the pulverized coal and reducing the amount of NOx generated.

As shown in Figures 1 to 6, a combustion burner 50 (50A, 50B, 50C) according to some embodiments includes a fuel nozzle 52 and a combustion air nozzle 54 arranged outside the fuel nozzle 52. The pulverized coal supply pipe 18 shown in Figure 9 is connected to the fuel nozzle 52, and a mixture of pulverized coal and conveying air (primary air) is ejected from the opening 52a of the fuel nozzle 52 into the combustion gas flow path Fc. Outside the fuel nozzle 52, combustion air (secondary air) is ejected from the opening 54a of the combustion air nozzle 54 into the combustion gas flow path Fc. In Figure 2, arrow a indicates the flow direction of the mixed air flow (hereinafter also simply referred to as the "flow direction"), and arrow b indicates the flow direction of the combustion air.

In Figures 1 to 6, a first member 56 (56a, 56b, 56c) and a second member 58 (58a, 58b, 58c) are provided inside the fuel nozzle 52 along the mixed air flow. The first member 56 (56a to 56c) has a first inclined surface 60 (60a, 60b, 60c) inclined with respect to the mixed air flow and a first inclined end 62 (62a, 62b, 62c) where the inclination of the first inclined surface 60 ends. The second member 58 (58a to 58c) has a second inclined surface 64 (64a, 64b, 64c) inclined with respect to the mixed air flow and a second inclined end 66 (66a, 66b, 66c) where the inclination of the second inclined surface 64 ends. The second inclined surface 64 (64a to 64c) is provided downstream of the first inclined surface 60 (60a to 60c) in the flow direction of the mixed air flow. In the first member 56 and the second member 58 that are arranged adjacent to each other, the first inclined surface 60 or the second inclined surface 64 is formed only on either the surface of the first member 56 that faces the second member 58 or the surface of the second member 58 that faces the first member 56.

The mixture supplied to the fuel nozzle 52 from the upstream side of the fuel nozzle 52 flows along the first member 56 and the second member 58, and the flow is first deflected along the first inclined surface 60 of the first member 56 arranged on the upstream side. Then, the mixture flow separates at the first inclined end 62 where the inclination of the first inclined surface 60 ends, forming a mixture recirculation area downstream of the first inclined end 62. In FIG. 2, the mixture flow in the recirculation area is indicated by the arrow d. In this recirculation area, the mixture flow is slow, so it ignites and a flame is formed, thereby carrying out flame holding. Similarly, in the second member 58 arranged downstream of the first member 56, a recirculation area is formed downstream of the second inclined end 66 where the second inclined surface 64 ends, and flame holding is carried out.

In the above configuration, the first member 56 and the second member 58 are arranged adjacent to each other, and the first inclined surface 60 or the second inclined surface 64 is formed only on either the surface of the first member 56 or the surface of the second member 58 that face each other. Therefore, the recirculation area of the mixed air flow formed at the first inclined end end 62 and the recirculation area of the mixed air flow formed at the second inclined end end 66 are formed at positions spaced apart from each other in a direction perpendicular to the flow direction of the mixed air flow. Therefore, interference between these recirculation areas can be suppressed. Therefore, a decrease in the ignition performance or flame holding performance of the first inclined end end 62 or the second inclined end end 66 can be suppressed.

In addition, the combustion air ejected from the combustion air nozzle 54 creates an oxygen-rich atmosphere on the outer periphery of the flame. If ignition occurs in this oxygen-rich atmosphere due to radiant heat from the outside, the temperature of the outer periphery of the flame will rise, and there is a risk of an increase in the amount of NOx generated. In contrast, according to the above embodiment, the first inclined end end 62 can suppress interference between the recirculation regions, so the flame formed in the recirculation region can be spread outward from the fuel nozzle 52. This increases the contact area between the reducing material (unburned matter) on the flame center side and the NOx generated on the outer periphery of the flame. This can promote the reduction of NOx on the outer periphery of the flame.

Also, as shown in Figs. 7 and 8 (described later) which show comparative examples, ash e floating inside the furnace 12 may adhere and accumulate near the opening of the fuel nozzle 152. According to the above embodiment, the first inclined surface 60 or the second inclined surface 64 is formed on only one side of the first member 56 or the second member 58, so that, as shown in Fig. 2, a poking rod 70 for scraping off the ash e accumulated at the opening of the fuel nozzle 52 can be easily inserted between the first member 56 and the second member 58 from the upstream side of the mixed air flow. This makes it easier to remove the ash.

Furthermore, since the first inclined surface 60 and the second inclined surface 64 are arranged at different positions in the flow direction of the mixed air flow, the area that the first inclined surface 60 and the second inclined surface 64 occupy in the flow path of the mixed air flow can be shifted in the flow direction of the mixed air flow. This allows the flow speed of the mixed air flow to be closer to the combustion speed, suppressing the blowing off of the flame, and enabling more stable flame holding.

In one embodiment, as shown in FIG. 2, the second inclined surface 64 of the second member 58 is disposed downstream of the mixed gas flow from the first inclined end end 62 of the first member 56. This allows the recirculation region d formed by the first inclined end end 62 and the second inclined end end 66 to be further apart in the flow direction of the mixed gas flow, thereby more effectively suppressing interference between the recirculation regions.

In one embodiment, as shown in FIG. 2, the second inclined end 66 of the second member 58 is aligned with the opening 52a of the fuel nozzle 52 to the combustion gas flow path Fc in the flow direction of the mixed gas. This allows a recirculation area d to be formed in the combustion gas flow path Fc. In one embodiment, the first inclined end 62 of the first member 56 is located upstream of the second inclined end 66 (inside the fuel nozzle 52). In another aspect, the first inclined end 62 of the first member 56 is located upstream of the most upstream end of the second inclined surface 64. This allows the recirculation area d formed by the first inclined end 62 and the second inclined end 66 to be spaced apart in the flow direction of the mixed gas, effectively suppressing interference between the recirculation areas.

In one embodiment, the first member 56 and the second member 58, except for the first inclined surface 60 or the second inclined surface 64, are formed as a plate-like body extending along the flow direction of the mixed gas flow, and both side surfaces of the plate-like body form flat surfaces along the flow direction of the mixed gas flow.

In one embodiment, the downstream end of the first member 56 and the second member 58 has a widening portion 68 that widens in a direction intersecting the flow direction of the mixed gas flow, and the first inclined end 62 or the second inclined end 66 is formed at one end of the widening portion 68. The widening portion 68 may have a constant width in the extension direction of the first member 56 or the second member 58, or may have different widths. The widening portion 68 may extend in a direction perpendicular to the flow direction of the mixed gas flow, or may be inclined relative to the perpendicular direction. For example, the widening portion 68 is easy to process if it is a flat surface, but it may also be a surface that is bent or curved in a concave or convex shape. In the exemplary embodiment shown in Figures 1 to 6, the flow direction cross section of the widening portion 68 is approximately an isosceles triangle, but this is not limited to this, and it may be a concave shape or a Y-shape.

In one embodiment, the combustion air ejected from the combustion air nozzle 54 may be a straight flow that follows the ejection direction of the mixed air flow. This makes it difficult for the combustion air to deflect toward the ejection opening of the fuel nozzle 52, suppressing external flame holding in the fuel nozzle 52 and reducing the amount of NOx generated.

In one embodiment, as shown in FIGS. 1 and 2, a secondary air nozzle 55 is provided outside the combustion air nozzle 54, and additional secondary air is injected from the secondary air nozzle 55 into the combustion gas flow path Fc.
In the exemplary embodiment shown in Fig. 1, an opening 54a of the combustion air nozzle 54 facing the combustion gas flow path Fc and an opening of the secondary air nozzle 55 facing the combustion gas flow path Fc coincide with an opening 52a of the fuel nozzle 52 in the flow direction of the mixed air flow. Note that the outer configuration of the fuel nozzle 52 is omitted in Figs. 5 and 6.

Figure 7 is a front view of a combustion burner 150 installed in a coal-fired boiler disclosed in Patent Document 1, and Figure 8 is a cross-sectional view taken along line D-D in Figure 7. In the combustion burner 150, the configuration of the combustion air nozzle and secondary air nozzle arranged on the outside of the fuel nozzle 152 is the same as that of the combustion burner 50 (50A) shown in Figure 1, but the configuration on the outside of the fuel nozzle 152 is omitted in Figures 7 and 8.

In the fuel nozzle 152, the first inclined surface 160 (160a, 160b) and the second inclined surface 164 (164a, 164b, 164c) are formed on the surfaces facing each other in the first member 156 (156a, 156b) and the second member 158 (158a, 158b, 158c) arranged adjacent to each other. Therefore, there is a risk that the recirculation areas formed by the first inclined end end 162 (162a, 162b) and the second inclined end end 166 (166a, 166b, 166c) may interfere with each other (indicated by i in FIG. 8). If the recirculation areas interfere with each other, the low flow rate area required for ignition formed in the recirculation area may be reduced, and the ignition performance may be reduced. Furthermore, because there are inclined surfaces on both sides of the first member 156 and the second member 158, there is a problem that it becomes difficult to insert the poking rod 70, which is used to scrape off the ash e that has accumulated at the opening of the fuel nozzle 152, between the first member 156 and the second member 158 from the upstream side of the mixed air flow.

In one embodiment, as shown in Figures 1 to 6, the second member 58 includes an outer second member 58 (58a, 58b) arranged to face the inner wall surfaces 52b and 52c of the fuel nozzle 52. The outer second member 58 (58a, 58b) has a second inclined surface 64 (64a, 64b) formed only on the surface facing the inner wall surfaces 52b and 52c of the fuel nozzle 52. This makes it possible to suppress interference between the recirculation region of the mixed gas flow formed at the second inclined end end 66 (66a, 66b) of the outer second member 58 (58a, 58b) and the recirculation region of the mixed gas flow formed at the first inclined end end 62 (62a, 62b) of the first member 56 arranged adjacent to the outer second member and opposite the inner wall surfaces 52b and 52c.

In one embodiment, as shown in FIG. 1 and FIG. 2, the second member 58 includes a center side second member 58 (58c) disposed between two first members 56 (56a, 56b). The center side second member 58 (58c) has a second inclined surface 64 (64c) formed on both a surface 72 facing the first member 56 (56a) on one side of the two first members 56 and a surface 74 facing the first member 56 (56b) on the other side. This allows a wide range of recirculation area to be formed at the second inclined end 66 (66c) of the center side second member 58 (58c), so that the flame retention performance of the center side second member 58 (58c) can be improved compared to the other second members 58 (58a, 58b).

The combustion burner 50 (50A) shown in Figures 1 and 2 has two first members 56 (56a, 56b), three second members 58 (58a, 58b), and a central first member 56 (56c) arranged in five rows along the flow direction of the mixed air flow. Since the first and second members 56 and 58 have a first inclined surface 60 or a second inclined surface 64 formed only on one of the opposing surfaces, the recirculation areas formed at the first inclined end end 62 and the second inclined end end 66 do not interfere with each other even between adjacent first and second members 56 and 58. Therefore, it is possible to suppress the deterioration of the flame-holding performance of each first member 56 and each second member 58 and the increase in the amount of NOx generated around the flame.

In one embodiment, both ends of the first member 56 and the second member 58 are supported by support members 75a and 75b that are installed on both inner wall surfaces 52b and 52c of the fuel nozzle 52. When the wide surfaces of the support members 75a and 75b are arranged along the flow direction of the mixed air flow, they also have the effect of straightening the mixed air flow.

In one embodiment, as shown in FIG. 3 and FIG. 4, the first member 56 includes a central first member 56 (56c) disposed between two second members 58 (58a, 58b). The central first member 56 (56c) has a first inclined surface 60 (60c) formed on both a surface 78 facing one of the two second members 58 (58a, 58b) and a surface 80 facing the other of the two second members 58 (58b). This allows a wide recirculation area to be formed at the first inclined end 62 (62c) of the central first member 56 (56c), thereby improving the flame retention performance of the central first member 56 (56c) compared to the other first members 56 (56a, 56b).

In the embodiment shown in Figures 3 and 4, the central first member 56 (56c) and the second member 58 (58a, 58b) are supported by support members 77a and 77b that are mounted on the opposing inner wall surfaces 52b and 52c of the fuel nozzle 52.

In one embodiment, as shown in FIG. 4, the first member 56 (56a, 56b) is provided so that its position can be adjusted freely along the flow direction of the mixed gas flow. This allows the first member 56 (56a, 56b) to be moved upstream or downstream in the fuel gas flow direction depending on, for example, the type of fuel (in the case of a coal-fired boiler 10, depending on the type of pulverized coal or the pulverized coal concentration of the mixed gas, etc.) or depending on the shape or arrangement of the first member 56 and the second member 58, thereby ensuring good internal flame stability.

In the exemplary embodiment shown in FIG. 4, a support member 76 is installed in the flow path of the mixed gas flow, and the first member 56 (56a, 56b) is attached to the support member 76 so that its position can be freely adjusted along the flow direction of the mixed gas flow. For example, the support member 76 is installed on the opposing inner wall surfaces of the fuel nozzle 52.

This embodiment can also be applied to the combustion burner 50 (50A) shown in Figures 1 and 2 and the combustion burner 50 (50C) shown in Figures 5 and 6, in addition to the combustion burner 50 (50B) according to the embodiment shown in Figures 3 and 4.

The combustion burner 50 (50C) shown in Figures 5 and 6 shows a modified example of the embodiment shown in Figures 1 and 2. In the combustion burner 50 (50C), the configuration of the combustion air nozzle 54 and secondary air nozzle 55 arranged outside the fuel nozzle 52 has the same configuration as the combustion burner 50 (50A) shown in Figure 1, but the configuration outside the fuel nozzle 52 is omitted in Figures 5 and 6.

The configuration of the combustion burner 50 (50C) according to this modification is different from that of the combustion burner 50 (50A) in that the second central member 58 (58c) is provided with a second inclined surface 64 (64c) only on one side (upper side as viewed from the flow direction a of the mixed gas flow), and the second inclined surface 64 (64c) is not provided on the other side (lower side as viewed from the flow direction a of the mixed gas flow). In addition, the first member 56 (56b) arranged adjacent to the side of the second central member 58 (58c) where the second inclined surface 64 (64c) is not provided has a first inclined surface 60 (60b) on both sides. The other configuration is the same as that of the combustion burner 50 (50A).
In this modification, the first inclined surface 60 or the second inclined surface 64 is formed only on one side of the mutually facing surfaces of the adjacently arranged first member 56 and second member 58, so that it is possible to avoid interference between the recirculation regions of the mixed air flow formed by the first inclined end end 62 and the second inclined end end 66. Therefore, it is possible to suppress a decrease in ignition performance and an increase in the amount of NOx generated at the outer periphery of the flame.

In one embodiment, as shown in Figures 1 to 6, the first member 56 and the second member 58 extend vertically and are spaced apart horizontally. This prevents the pulverized coal contained in the mixed air flow flowing through the fuel nozzle 52 from accumulating on the individual members such as the first member 56 and the second member 58, preventing a decrease in flame stability. In the embodiment shown in Figures 1 to 6, the secondary air nozzle 55 is provided above or below the combustion air nozzle 54, and is not provided to the side of the combustion air nozzle 54. This is because if it is provided to the side of the combustion air nozzle 54, the flame portion will not spread easily.

In one embodiment, the first member 56 and the second member 58 can extend horizontally and be spaced apart vertically. This can relatively weaken external ignition in the vertical direction, and when the secondary air nozzle 55 is disposed in a vertical position, it can reduce the formation of a high-temperature, high-oxygen region due to the secondary air from the secondary air nozzle 55.

In one embodiment, as shown in Figures 1 to 6, when the first member 56 and the second member 58 are vertical splitters, arranging the secondary air nozzle 55 to the side of the combustion air nozzle 54 makes it difficult for the flame to spread to the side. For this reason, the secondary air nozzle 55 is usually arranged only on the vertical outside of the combustion air nozzle 54. In the outer regions of the inner wall surfaces 52b and 52c, the internal flame holding performed in each of the above embodiments suppresses peripheral ignition, and suppresses an increase in the amount of NOx generated.

The contents described in each of the above embodiments can be understood, for example, as follows:

1) A combustion burner (50 (50A, 50B, 50C)) according to one embodiment includes a fuel nozzle (52) that ejects a fuel gas mixture of fuel and air, a combustion air nozzle (54) that ejects combustion air from the outside of the fuel nozzle, a first member 56 (56a, 56b, 56c) that is disposed inside the fuel nozzle and has a first inclined surface (60 (60a, 60b, 60c)) that is inclined with respect to the flow of the fuel gas and a first inclined end (62 (62a, 62b, 62c)) where the inclination of the first inclined surface ends, and a first member 56 (56a, 56b, 56c) that is inclined with respect to the flow of the fuel gas from the first inclined surface. and a second member (58 (58a, 58b, 58c)) having a second inclined surface (64 (64a, 64b, 64c)) inclined with respect to the flow of the fuel gas and a second inclined end (66 (66a, 66b, 66c)) where the inclination of the second inclined surface ends, the first member and the second member are disposed adjacent to each other, and the first inclined surface or the second inclined surface is formed only on either the surface of the first member facing the second member or the surface of the second member facing the first member.

According to this configuration, the first member and the second member arranged adjacent to each other have the first inclined surface or the second inclined surface formed only on either the surface of the first member facing the second member or the surface of the second member facing the first member, so that the recirculation area of the mixed gas flow formed at the first inclined end end and the recirculation area of the mixed gas flow formed at the second inclined end end are formed at positions separated from each other in a direction perpendicular to the flow direction of the fuel gas. Therefore, interference between the two can be suppressed. As a result, the low flow velocity area formed in each recirculation area is not reduced, so that the deterioration of the ignition performance or flame holding performance of the first inclined end end or the second inclined end end can be suppressed. In addition, by setting the inclination direction of the first inclined surface and the second inclined surface outward, the flame can be spread toward the outside of the fuel nozzle, so that the contact area between the reducing material (unburned matter) on the flame center side and the NOx generated on the flame periphery increases. This can promote the reduction of NOx on the flame periphery. Furthermore, since the first inclined surface or the second inclined surface is formed on only one side of the first member or the second member, it becomes easier to insert a picking rod between the first member and the second member to scrape off ash that has adhered to the opening of the fuel nozzle, making it easier to remove ash that has adhered near the opening of the fuel nozzle.

2) A combustion burner according to another embodiment is the combustion burner described in 1), in which the second member (58) includes an outer second member (58 (58a, 58b)) in which the second inclined surface is formed only on the surface of the second member facing the inner wall surface (52b, 52c) of the fuel nozzle.

With this configuration, the second inclined surface is formed only on the surface of the outer second member that faces the inner wall surface of the fuel nozzle, so that it is possible to prevent interference between the recirculation area of the mixed air flow formed at the second inclined end of the outer second member and the recirculation area of the mixed air flow formed at the first inclined end of the adjacent first member arranged on the opposite side to the inner wall surface of the fuel nozzle.

3) A combustion burner according to yet another embodiment is the combustion burner described in 1) or 2), in which the second member (58) is a central second member arranged between the two first members, and includes a central second member (58 (58c)) in which the second inclined surface is formed on both the surface (72) of the second member facing the first member (56 (56a)) on one side of the two first members (56 (56a, 56b)) and the surface (74) of the second member facing the first member (56 (56b)) on the other side of the two first members.

With this configuration, the second member includes the above-mentioned central second member having second inclined surfaces on both sides, so that a wide recirculation region can be formed in a direction intersecting the flow direction of the fuel gas at the end of the second inclination of the central second member. This makes it possible to improve the flame holding performance of the central second member compared to other second members.

4) A further aspect of the combustion burner is the combustion burner described in 2), in which the first member (56) is a central first member arranged between the two second members (58 (58a, 58b)), and includes a central first member (56 (56c)) in which the first inclined surface is formed on both the surface (78) of the first member facing the second member (58 (58a)) on one side of the two second members, and the surface (80) of the first member facing the second member (58 (58b)) on the other side of the two second members.

With this configuration, the first member includes the above-mentioned central first member having first inclined surfaces on both sides, so that a wide recirculation area can be formed at the end of the first inclination of the central first member. This makes it possible to improve the flame holding performance of the central first member compared to other first members.

5) A further aspect of the combustion burner is the combustion burner described in any one of 1) to 4), in which the first member (56 (56a, 56b)) is arranged so that its position can be freely adjusted along the flow direction of the fuel gas.

With this configuration, the position of the first member can be freely adjusted along the fuel gas flow direction, and good internal flame stability can be ensured by, for example, changing the position of the first member to the upstream or downstream side of the fuel gas flow direction depending on the type of fuel and the shapes or positions of the first and second members.

6) A further aspect of the combustion burner is the combustion burner described in any one of 1) to 5), in which the first member and the second member extend vertically and are spaced apart horizontally.

With this configuration, the first member and the first member extend in the vertical direction, so that the fuel contained in the fuel gas flowing through the fuel nozzle is prevented from accumulating on the individual members, thereby preventing a decrease in flame stability performance.

7) A combustion burner according to yet another aspect is a combustion burner according to any one of 1) to 5), in which the first member and the second member extend along the horizontal direction and are spaced apart in the vertical direction.

With this configuration, the first and second members extend horizontally, so external ignition in the vertical direction can be relatively weakened. Therefore, if combustion air nozzles or additional secondary air nozzles are arranged above and below, the formation of high-temperature, high-oxygen regions due to the air from these nozzles can be reduced.

8) A further aspect of the combustion burner is the combustion burner described in 6), which is equipped with a secondary air nozzle (55) that ejects additional secondary air from the vertical outside of the combustion air nozzle (54).

In the case of a vertical splitter in which the first and second members have the configuration described above in 6), arranging the secondary air nozzle (55) to the side of the combustion air nozzle (54) makes it difficult for the flame to spread to the side, so by arranging the secondary air nozzle (55) only on the outside in the vertical direction of the combustion air nozzle (54), the flame can easily spread to the side.

9) A boiler (10) according to one embodiment includes a furnace (12) having a combustion gas flow path (Fc) formed therein, a heat transfer tube facing the combustion gas flow path, and a combustion burner according to any one of 1) to 8) provided in the furnace.

With this configuration, a boiler equipped with the above-mentioned combustion burner can suppress interference between the recirculation areas of the mixed air flow formed in the adjacent first and second members, thereby suppressing a decrease in the ignition performance or flame-holding performance of the mixed air flow at the first or second inclination end end. In addition, suppressing interference between the recirculation areas can promote the reduction of NOx on the outer periphery of the flame, and makes it easier to insert a poking rod between the first and second members, making it easier to remove ash accumulated near the opening of the fuel nozzle.

REFERENCE SIGNS LIST 10 Coal-fired boiler 12 Furnace 14 Combustion device 16 Flue 18 Pulverized coal supply pipe 18a, 18b, 18c, 18d, 24a, 24b, 24c, 24d Branch pipe 20 Mill 22 Wind box 24 Air duct 26 Blower 28 Additional air nozzle 30 Branch duct 32 Gas duct 34, 36, 38 Superheater 40, 42 Reheater 44, 46 Economizer 48 Air heater 50 (50A, 50B, 50C), 50a, 50b, 50c, 50d, 150 Combustion burner 52, 152 Fuel nozzle 52a, 152a Opening 52b, 52c Inner wall surface 54 Combustion air nozzle 54a Opening 55 Secondary air nozzle 56 (56a, 56b, 56c), 156 (156a, 156b) First member 58 (58a, 58b, 58c), 158 (158a, 158b, 158c) Second member 60 (60a, 60b, 60c), 160 (160a, 160b) First inclined surface 62 (62a, 62b, 62c), 162 (162a, 162b) First inclined end 64 (64a, 64b, 64c), 164 (164a, 164b, 164c) Second inclined surface 66 (66a, 66b, 66c), 166 (166a, 166b, 166c) Second inclined end 68 Widening portion 70 Prodding bar 72, 74, 78, 80 Surface 75a, 75b, 76, 77a, 77b, 175a, 175b Support member C Flame swirl flow F1, F2, F3, F4 Flame Fc Combustion gas flow path X Combustion region Y Reduction region d Mixture flow recirculation region e Ash i Interference

Claims (8)

a fuel nozzle for ejecting a fuel gas mixture of fuel and air;
a combustion air nozzle that ejects combustion air from the outside of the fuel nozzle;
a first member disposed inside the fuel nozzle, the first member having a first inclined surface inclined with respect to a flow of the fuel gas and a first inclined end at which the inclination of the first inclined surface ends;
a second member having a second inclined surface disposed downstream of the first inclined surface in the flow of the fuel gas, the second inclined surface being inclined with respect to the flow of the fuel gas and a second inclined end where the inclination of the second inclined surface ends,
The first member and the second member are disposed adjacent to each other,
the first inclined surface or the second inclined surface is formed only on either a surface of the first member facing the second member or a surface of the second member facing the first member ,
the second member includes an outer second member, the second inclined surface being formed only on a surface of the second member facing an inner wall surface of the fuel nozzle;
Combustion burner. a fuel nozzle for ejecting a fuel gas mixture of fuel and air;
a combustion air nozzle that ejects combustion air from the outside of the fuel nozzle;
a first member disposed inside the fuel nozzle, the first member having a first inclined surface inclined with respect to a flow of the fuel gas and a first inclined end at which the inclination of the first inclined surface ends;
a second member having a second inclined surface disposed downstream of the first inclined surface in the flow of the fuel gas, the second inclined surface being inclined with respect to the flow of the fuel gas and a second inclined end where the inclination of the second inclined surface ends,
The first member and the second member are disposed adjacent to each other,
the first inclined surface or the second inclined surface is formed only on either a surface of the first member facing the second member or a surface of the second member facing the first member,
the second member is a central second member disposed between the two first members, and the second inclined surface is formed on both a surface of the second member facing the first member on one side of the two first members and a surface of the second member facing the first member on the other side of the two first members ;
Combustion burner. The first member includes a central first member disposed between the two second members, the central first member having the first inclined surface formed on both a surface of the first member facing one of the two second members and a surface of the first member facing the other of the two second members.
The combustion burner according to claim 1 . The first member is provided so as to be freely position-adjustable along a flow direction of the fuel gas.
Combustion burner according to any one of claims 1 to 3 . The first member and the second member extend along a vertical direction and are spaced apart in a horizontal direction.
Combustion burner according to any one of claims 1 to 4 . The first member and the second member extend along a horizontal direction and are spaced apart in a vertical direction.
Combustion burner according to any one of claims 1 to 4 . A secondary air nozzle is provided which ejects additional secondary air from the outside of the combustion air nozzle in the vertical direction.
Combustion burner according to claim 5 . A furnace having a combustion gas flow path formed therein;
a heat transfer tube provided facing the combustion gas flow path;
A combustion burner according to any one of claims 1 to 7 , which is provided in the furnace;
A boiler equipped with

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