JP6513422B2 - Combustion burner, boiler, and method of burning fuel gas - Google Patents

Description

  The present invention relates to a combustion burner, a boiler, and a method of burning a fuel gas.

  Pulverized coal burners as disclosed in Patent Literature 1 and Patent Literature 2 are known as combustion burners used in a pulverized coal burning boiler using coal as an example of a carbon-containing solid fuel. Patent Document 1 discloses a technique for providing a split member functioning as an internal flame holding mechanism at a flow path front portion of a fuel burner. The split member of Patent Document 1 is installed near the center of the outlet opening of the pulverized coal burner, divides the flow path of pulverized coal and air, disturbs the flow internally, and forms a recirculation zone in front of the split. , Acting as an internal flame holding mechanism. In Patent Document 2, a split is provided in the flow path, and a mixed gas of pulverized coal fuel and air is supplied from the mixed fluid supply path to the fuel nozzle, the flow path of the mixed fluid is branched in split, and the pulverized coal fuel concentration is increased. Disclose technology.

JP, 2011-127836, A JP, 2009-204256, A

  The prior art ensures ignition by installing a flame holding device that generates a circulating vortex at the nozzle outlet. In this case, the effect is largely influenced by the mixing ratio of air and fuel and the physical quantity of the flow which controls the strength of the vortex, and the condition of use is often limited. Therefore, it is not perfect to always obtain stable ignition.

  An aspect of the present invention aims to provide a combustion burner, a boiler, and a method of burning a fuel gas that can enhance internal flame holding to obtain stable ignition.

  According to the first aspect of the present invention, a fuel gas flow path including a fuel gas injection port for injecting a fuel gas obtained by mixing a carbon-containing solid fuel and primary air, and an end portion provided with the fuel gas injection port A secondary air flow path including a fuel nozzle having the following structure, a secondary air injection port disposed around the fuel gas injection port for injecting secondary air, and an end provided with the secondary air injection port: A flame holding member disposed in the fuel gas flow path on the upstream side of the fuel gas from the fuel gas injection port, and the fuel in the fuel gas flow path rather than the flame holding member And a heating member disposed upstream of the gas flow passage, wherein the heating member includes a first portion disposed in the fuel gas flow passage and a second portion disposed in the secondary air flow passage. A combustion burner is provided, comprising and heated by said secondary air

  According to the first aspect of the present invention, since the fuel gas heated by the heating member is supplied to the flame stabilizing member disposed in the fuel gas flow path, ignition in the flame stabilizing member is promoted. The heat exchange between the secondary air and the fuel gas by the heating member causes the fuel gas to have a high temperature around the heating member, thereby promoting internal flame holding. In addition, when the fuel gas is heated, the carbon-containing solid fuel that constitutes the fuel gas is also heated, and the volatile component contained in the carbon-containing solid fuel is evaporated and easily released from the carbon-containing solid fuel. Therefore, the fuel gas is a flame holding member, ignition is promoted, and internal flame holding can be realized stably. Internal flame holding means a state in which a flame is generated in the fuel gas flow path. In internal flame holding, a flame is generated in a low temperature and low oxygen space as compared with external flame holding. Therefore, the amount of NOx generation can be suppressed.

  In the first aspect of the present invention, the first central plane including the central axis of the fuel gas flow channel, and the second central plane orthogonal to the first central plane and including the central axis, The fuel gas flow path includes a first inner surface, a second inner surface facing the first inner surface with the first central surface interposed therebetween, a third inner surface orthogonal to the first surface, and the second central surface The first inner surface and the second inner surface are surrounded by the third inner surface and the fourth inner surface facing each other, and the first inner surface and the second inner surface have the same distance to the first central surface toward the fuel gas injection port. The third inner surface and the fourth inner surface may have the same distance from the second central surface toward the fuel gas injection port.

  Thereby, internal flame stabilization is realized stably. The first inner surface and the second inner surface face the fuel gas injection port at the same distance to the first central surface, and the third inner surface and the fourth inner surface face the fuel gas injection port, Since the distance to the second surface is the same, the flow of fuel gas is stabilized, and a stable internal flame holding is realized.

  In the first aspect of the present invention, an angle (θ) between the inner surface (71) of the secondary air nozzle of the secondary air flow path (6) and the first central surface is 0 ° or more and 30 ° or less May be.

  As a result, the secondary air flow path through which the secondary air flows has a form in which the secondary air injection port, which is the outlet, is narrowed more than the inlet. Therefore, the secondary air can be supplied to the heating member by increasing the flow velocity on the downstream side of the upstream side of the secondary air injection port. When the angle is 30 ° or more, the angle to the furnace increases, and the amount of radiant heat received increases. In addition, when the outlet flow velocity is constant, the flow velocity on the inlet side becomes slower and the heat transfer coefficient decreases. Therefore, there is a concern about high temperature oxidation due to temperature rise of the nozzle and deformation associated therewith. In addition, designing the flow velocity to increase toward the tip also has the effect of preventing flashback. For this reason, it is preferable to limit within about 30 degrees.

  In the first aspect of the present invention, a plurality of the first portions of the heating member may be disposed at predetermined intervals in a direction orthogonal to the central axis of the fuel gas flow channel.

  Thus, the fuel gas flowing in the direction parallel to the central axis is efficiently heated by the plurality of first portions. The predetermined distance is a distance at which the entire amount of fuel gas can be ignited inside the burner without mutual interference, and is, for example, 1.0 times or more and 3.0 times or less of the pipe diameter. Furthermore, in order to set the predetermined interval to the optimum value, it can be determined by experiment, or can be determined by simulation based on the structure, size, etc. of the combustion burner.

  In the first aspect of the present invention, the heating member includes a first group including a plurality of the first portions spaced apart in a first axial direction orthogonal to a central axis of the fuel gas flow path; And a second group disposed at a position different from the first group with respect to a direction parallel to the central axis, and the first portion and the second group of the first group with respect to the first axial direction. The first part of the may be arranged at a different position.

  Thus, the fuel gas is efficiently heated by the first portions arranged in a staggered manner. By arranging the first portions in a staggered manner, the contact area between the fuel gas and the first portion increases, and the fuel gas is efficiently heated. When the fuel gas is heated, the carbon-containing solid fuel that constitutes the fuel gas is also heated, and the volatile component contained in the carbon-containing solid fuel is vaporized and easily released from the carbon-containing solid fuel. Therefore, ignition is promoted, and internal flame holding can be reliably obtained.

  In the first aspect of the present invention, a plurality of the first portions of the heating member may be disposed at predetermined intervals in a direction orthogonal to the central axis of the fuel gas flow channel.

  Thereby, internal flame stabilization can be realized stably. If the flow of fuel gas is disturbed, the possibility of external flame holding increases. Disturbance of the flow of the fuel gas is suppressed by arranging a plurality of heating members at predetermined intervals. Therefore, internal flame stabilization is realized stably.

  In the first aspect of the present invention, the flame-holding member includes a third portion disposed in the fuel gas passage and a fourth portion disposed in the secondary air passage, The flame stabilizing member may be heated by air.

  Thus, the third portion of the flame stabilizing member can be efficiently heated by heat exchange between the fourth portion of the flame stabilizing member and the secondary air, and a stable internal flame stabilization can be realized.

  In the first aspect of the present invention, the surface area of the second portion of the heating member may be larger than the cross-sectional area orthogonal to the longitudinal direction of the first portion.

  Thereby, in the secondary air flow path, the contact area between the secondary air and the second portion is increased, so that the first portion is efficiently heated.

  In the first aspect of the present invention, it is provided on the outer surface of at least one of the heating member and the flame stabilizing member facing at least the upstream side of the fuel gas flow path, and from the pulverized coal, the heating member and the flame retaining member You may have a protective film which protects at least one of these.

  Thereby, deterioration of at least one of the heating member and the flame stabilizing member due to the collision of the pulverized coal can be suppressed.

  In the first aspect of the present invention, the distance between the outer surface of the flame stabilizing member and the virtual line increases in a direction toward the downstream side of the fuel gas flow path with respect to the virtual line parallel to the central axis. And a second inclined surface which is inclined such that a distance between the first inclined surface and the first inclined surface increases in a direction toward the downstream side of the fuel gas flow channel.

  Thus, the fuel gas flows along the first and second inclined surfaces and then flows toward the front side of the flame stabilizing member. The fuel gas flows into the front side of the flame stabilizing member without being separated from the flame stabilizing member, so that the internal flame stabilization can be surely realized in the front surface of the flame stabilizing member.

  In the first aspect of the present invention, at least one of the heating member and the flame stabilizing member is disposed in a rod-like fifth portion disposed in the fuel gas passage, and in the secondary air passage, A first portion including a sixth portion heated by the next air and located at an intermediate position between the one end portion and the other end portion of the fifth portion; one end portion and the other end portion of the fifth portion; And a second portion connecting the sixth portion, wherein the surface area of the sixth portion is larger than the cross-sectional area orthogonal to the longitudinal direction of the fifth portion, and in the cross section orthogonal to the longitudinal direction of the fifth portion The cross-sectional area of the first portion may be larger than the cross-sectional area of the second portion.

  Thus, the fuel gas can be in contact with the fifth portion for a long time, so that the fuel gas can be efficiently heated. Further, the temperature of the fifth portion is made uniform, and a stable internal flame holding is realized. That is, the second portion is closer to the sixth portion than the first portion and is easily heated by the secondary air. By making the cross-sectional area of the first portion larger than the cross-sectional area of the second portion, the temperature of the fifth portion can be made uniform.

  In the first aspect of the present invention, the fifth portion is rod-shaped, and in a cross section orthogonal to the longitudinal direction of the fifth portion, the cross-sectional area gradually increases from the second portion toward the first portion May be

  Thereby, the temperature equalization of the fifth portion is further achieved, and a stable internal flame stabilization is realized.

  According to a second aspect of the present invention there is provided a boiler comprising the combustion burner of the first aspect.

  According to the second aspect of the present invention, the generation amount of NOx can be suppressed.

According to a third aspect of the present invention, the fuel gas flow passage of the fuel nozzle toward the fuel gas injection port, supplying the fuel gas that is a mixture of carbon-containing solid fuel and primary air, the fuel of the fuel nozzle Injecting the fuel gas from the gas injection port, and supplying secondary air to the secondary air flow path of the secondary air nozzle, and the secondary air nozzle disposed around the fuel gas injection port Injecting the secondary air from the secondary air injection port, and having a first portion disposed in the fuel gas flow path and a second portion disposed in the secondary air flow path; Preheating the fuel gas with a heating member in which the first portion is heated by heating the second portion with the next air; and the fuel gas flow in the fuel gas flow path rather than the first portion The fuel gas from the fuel gas injection port downstream of the passage Supplying the fuel gas preheated by the heating member to a flame holding member disposed upstream, and bringing the fuel gas flow path into an internal flame holding state by the flame holding member; A method of burning fuel gas is provided.

  According to the third aspect of the present invention, the generation amount of NOx can be suppressed.

  According to an aspect of the present invention, a combustion burner, a boiler, and a method of burning a fuel gas are provided that can enhance internal flame holding to obtain stable ignition.

FIG. 1: is a schematic block diagram which shows an example of the boiler which concerns on 1st Embodiment. FIG. 2 is a side sectional view showing an example of the combustion burner according to the first embodiment. FIG. 3 is a view showing an example of the combustion burner according to the first embodiment. FIG. 4 is a view showing an example of the combustion burner according to the first embodiment. FIG. 5 is an enlarged view of a part of the inner surface of the fuel nozzle according to the first embodiment. FIG. 6 is a cross-sectional view showing an example of the heating member according to the first embodiment. FIG. 7 is a cross-sectional view showing an example of the heating member or the flame stabilizing member according to the first embodiment. FIG. 8 is a cross-sectional view showing an example of the heating member or the flame stabilizing member according to the first embodiment. FIG. 9 is a schematic view showing the flow of fuel gas around the flame stabilizing member according to the first embodiment. FIG. 10 is a schematic view showing the flow of fuel gas around the flame stabilizing member according to the first embodiment. FIG. 11 is a view showing an arrangement example of the heating member according to the first embodiment. FIG. 12 is a schematic view for explaining the combustion method of the fuel gas according to the first embodiment. FIG. 13 is a schematic view for explaining a fuel gas combustion method according to a comparative example. FIG. 14 is a view showing an example of the heating member according to the second embodiment. FIG. 15 is a view showing an example of the heating member according to the third embodiment. FIG. 16 is a view showing an example of the heating member according to the fourth embodiment. FIG. 17 is a view showing an example of the heating member according to the fourth embodiment. FIG. 18 is a view showing an example of the flame stabilizing member according to the fifth embodiment. FIG. 19 is a perspective view showing an example of the flame stabilizing member according to the fifth embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of each embodiment described below can be combined as appropriate. In addition, some components may not be used.

First Embodiment
The first embodiment will be described. FIG. 1: is a schematic block diagram which shows an example of the boiler 100 which concerns on this embodiment. The boiler 100 is a pulverized coal burning boiler using pulverized coal which is pulverized coal as an example of a carbon-containing solid fuel.

  As shown in FIG. 1, the boiler 100 is a steam using a furnace 110 that grinds pulverized coal to generate a combustion gas, a combustion device 120 that burns the pulverized coal, and thermal energy of the combustion gas generated in the furnace 110 And a steam generator 140 for producing

  The furnace 110 has a combustion chamber 111 and a flue 112 disposed above the combustion chamber 111. Pulverized coal is burned in the combustion chamber 111 to generate combustion gas.

  The combustion device 120 includes a combustion burner 1, a pulverized coal supply device 121 that supplies pulverized coal to the combustion burner 1, and an air supply device 122 that supplies secondary air to the combustion burner 1. A plurality of combustion burners 1 are provided in the furnace 110.

  The pulverized coal supply device 121 includes a pulverized coal machine 123 that generates pulverized coal, and a pulverized coal supply pipe 124 that connects the pulverized coal machine 123 and the combustion burner 1. The pulverized coal machine 123 includes a mill that crushes coal to produce pulverized coal. The pulverized coal produced by the pulverized coal machine 123 is supplied to the combustion burner 1 via a pulverized coal supply pipe 124.

  The air supply device 122 includes a blower 125, an air box 126, and an air supply pipe 127 connecting the blower 125 and the air box 126. The blower 125 supplies air to the air box 126 via the air supply pipe 127. The air box 126 supplies the air from the blower 125 to the combustion burner 1.

  The steam generator 140 exchanges heat between the combustion gas generated by the furnace 110 and the feed water to the boiler to generate steam. The steam generator 140 has a superheater 141, a reheater 142, and an economizer 143. The superheater 141, the reheater 142, and the economizer 143 are disposed in the flue 112.

  The flue 112 is connected to the exhaust gas flow path 113. The combustion gas (exhaust gas) subjected to heat exchange with the feed water in the steam generator 140 is sent to the exhaust gas channel 113. An air heater 114 is provided in the exhaust gas flow path 113. The air heater 114 uses the heat of the combustion gas flowing through the exhaust gas flow path 113 to heat the secondary air flowing through the air supply pipe 127. As a result, the temperature of the secondary air supplied to the combustion burner 1 rises.

  Although not shown, the exhaust gas flow path 113 is provided with a NOx removal device, an electrostatic precipitator, a desulfurization device, and the like. The exhaust gas passage 113 is connected to a chimney.

  Next, an example of the operation of the boiler 1 will be described. The pulverized coal produced by the pulverized coal machine 123 flows through the pulverized coal supply pipe 124 together with the primary air (the air for transfer) and is supplied to the combustion burner 1. The secondary air (combustion air) heated by the air heater 114 flows through the air supply pipe 127 and is then supplied to the combustion burner 1 via the air box 126. As shown in FIG. 2, the combustion burner 1 injects into the combustion burner 1 a fuel gas Ga in which pulverized coal and primary air are mixed. The combustion burner 1 also transfers part of the heat of the heated secondary air Gb to the heating member 9 when the secondary air Gb passes through the secondary air flow path 6 around the fuel nozzle 4. The temperature of the heating member 9 is raised. The fuel gas Ga is preheated by the heating member 9 and then ignited by the flame stabilizing member 8 to generate a flame, thereby generating a combustion gas. The combustion gas Ga becomes a flame and is injected into the combustion chamber 111 of the furnace 110. The secondary air Gb ejected from the secondary air injection port 5 is supplied to the flame to complete the combustion. Here, the secondary air Gb is divided into the auxiliary air nozzles 22 installed vertically above and below the combustion burner 1 and supplied with the auxiliary air Gd ejected from the auxiliary air nozzles 22 so that the combustion is completed. It is also good. The combustion gas generated in the combustion chamber 111 flows through the flue 112.

  The steam generator 140 exchanges heat between the combustion gas from the combustion chamber 111 and the water supplied to the boiler supplied by a water supply pump (not shown) to generate steam. The feed water supplied by the feed pump is preheated by the economizer 143 and then heated while flowing through the water pipe provided in the furnace 110 to become saturated steam. Saturated steam is supplied to the steam drum. The saturated steam of the steam drum is supplied to the superheater 141. The saturated steam of the superheater 141 is superheated by the combustion gas and becomes superheated steam. The superheated steam generated by the superheater 141 is supplied to a steam turbine of a power plant (not shown). Further, the steam which has been worked by the steam turbine is condensed by water in a condenser (not shown), and is again supplied to the reheater 142 as feed water to the boiler by the feed water pump, and is again overheated and supplied to the steam turbine.

  The combustion gas that has passed through the economizer 143 of the flue 112 is supplied to a denitrification device (not shown) disposed in the exhaust gas passage 113. The NOx removal system removes harmful substances such as NOx contained in the combustion gas by the catalyst. Further, the combustion gas is supplied to an electric dust collector (not shown) disposed in the exhaust gas flow path 113 and a desulfurizer (not shown). The electrostatic precipitator removes particulate matter contained in the combustion gas. The desulfurization unit removes sulfur contained in the combustion gas. The air cleaned by the NOx removal system, the electrostatic precipitator, the desulfurization system, etc. is discharged to the atmosphere from a chimney not shown.

  The amount of generated NOx is suppressed by igniting the inside of the primary air of the fuel gas Ga in which the pulverized coal and the primary air are mixed and holding the flame in the reducing atmosphere. Further, even after the secondary air Gb and the auxiliary air Gd are supplied, the reducing atmosphere of the flame is maintained, and the combustion chamber 111 is expanded to reduce NOx generated by the combustion of the pulverized coal in the combustion chamber 111, and then additional The additional combustion of additional air from the airport 144 may complete the oxidation combustion of the pulverized coal. As a result, the amount of NOx generated by the combustion of the pulverized coal is suppressed.

  Next, the combustion burner 1 according to the present embodiment will be described. FIG. 2 is a side sectional view showing an example of the combustion burner 1 according to the present embodiment. FIG. 3 is a view showing an example of the combustion burner 1 according to the present embodiment. FIG. 4 is a view showing an example of the combustion burner 1 according to the present embodiment.

  As shown in FIGS. 2, 3 and 4, the combustion burner 1 includes a fuel nozzle 4 for injecting a fuel gas Ga, a secondary air nozzle 7 for injecting a secondary air Gb, and a flame holding member 8. A heating member 9 is provided. FIG. 3 is a front view seen from the inside of the combustion chamber 111 to show the fuel gas injection port 2 and the secondary air injection port 5 of the combustion burner 1, and FIG. 4 shows only the flame holding member 8 and the heating member 9 only. As viewed from within the combustion chamber 111.

  The fuel gas Ga is a gas in which pulverized coal which is a carbon-containing solid fuel and primary air which is air for transportation are mixed. The secondary air Gb is combustion air. The secondary air Gb is heated to a predetermined temperature by the air heater 114 or the like, and the temperature of the secondary air Gb is higher than the temperature of the fuel gas Ga. The temperature of the secondary air Gb is, for example, 300 ° C. or more and 350 ° C. or less. The temperature of the fuel gas Ga is such a temperature that the pulverized coal does not ignite, and is, for example, 60 [° C.] or more and 80 [° C.] or less.

  The fuel nozzle 4 has a fuel gas injection port 2 for injecting the fuel gas Ga, and a fuel gas flow path 3 through which the fuel gas Ga injected from the fuel gas injection port 2 flows. The fuel gas injection port 2 is provided at an end of the fuel gas flow path 3. The cross-sectional area of the fuel gas flow path 3 is the same toward the fuel gas injection port 2.

  The secondary air nozzle 7 has a secondary air injection port 5 for injecting the secondary air Gb, and a secondary air flow path 6 through which the secondary air Gb injected from the secondary air injection port 5 flows. The secondary air injection port 5 is provided at an end of the secondary air flow path 6. The secondary air injection port 5 is disposed around the fuel gas injection port 2.

  In the present embodiment, the amount of supply of primary air supplied to the fuel gas passage 3 can be conveyed without the fuel gas being immediately ignited in the fuel gas passage 3 and stagnant pulverized coal serving as fuel. Set the amount of air (amount of oxygen). Therefore, the nozzle input air amount, which is the sum of the supply amount of the primary air supplied to the fuel gas flow path 3 and the supply amount of the secondary air supplied to the secondary air flow path 6, is 100%. In this case, the nozzle input air amount is set based on the theoretical combustion air amount with pulverized coal that is the fuel and the excess amount thereof, and the supply amount of primary air supplied to the fuel gas flow path 3 is, for example, 60% or more. [%] Or less, and the amount of secondary air supplied to the secondary air flow path 6 with this is 10 [%] or more and 40 [%] or less.

  The fuel gas flow path 3 has a central axis AX. The fuel nozzle 4 is disposed around the central axis AX. The secondary air nozzle 7 is arranged around the fuel nozzle 4.

  In the following description, a direction parallel to the central axis AX will be appropriately referred to as an axial direction. In addition, a direction parallel to the first axis as the width direction of the combustion burner 1 in a plane orthogonal to the central axis AX is appropriately referred to as a lateral direction, and a second axis orthogonal to both the central axis AX and the first axis. The direction parallel to is suitably referred to as the vertical direction. Further, a surface extending in the lateral direction including the central axis AX is referred to as a first central surface, and a surface orthogonal to the first surface and extending in the longitudinal direction including the central axis AX is referred to as a second central surface.

  The flame stabilizing member 8 is disposed in the fuel gas flow path 3. In the present embodiment, a plurality of flame stabilizing members 8 are arranged in parallel at intervals in the longitudinal direction such that the longitudinal direction is the lateral direction. The flame stabilizing member 8 has a shape in which the cross-sectional width perpendicular to the longitudinal direction of the flame stabilizing member 8 expands toward the downstream of the fuel gas flow channel 3. As shown in FIG. 2, in the present embodiment, the cross section of the flame stabilizing member 8 is a triangle. The cross section of the flame stabilizing member 8 is not limited to a triangle, and may be semicircular.

  The heating member 9 includes a first portion 91 disposed in the fuel gas flow path 3 and a second portion 92 disposed in the secondary air flow path 6. The first portion 91 of the heating member 9 is disposed upstream of the fuel gas passage 3 than the flame stabilizing member 8. In the heating member 9, a part of the amount of heat is transferred by the heated secondary air Gb, and the temperature is raised. Since the second portion 92 is disposed in the secondary air flow path 6, the second portion 92 is heated by the secondary air Gb flowing through the secondary air flow path 6. The heat of the heated second portion 92 is transferred to the first portion 91. Therefore, the temperature of the first portion 91 is higher than the temperature of the fuel gas Ga. The first portion 91 is heated to approximately 200 ° C. to 350 ° C.

  The heating member 9 is formed of a material of high thermal conductivity. In the present embodiment, the heating member 9 contains copper.

  In the present embodiment, the flame stabilizing member 8 is also formed of a material of high thermal conductivity. In the present embodiment, the heating member 9 and the flame holding member 8 contain copper, and the heating member 9 and the flame holding member 8 have chromium-based surfaces in order to have abrasion resistance to pulverized coal and high temperature oxidation resistance. It is preferable to coat with a nickel-based material or a material, or to form a coating with a ceramic material.

  The inner surface 13 of the fuel gas passage 3 is a first upper inner surface 131 in the vertical direction, and a second lower inner surface 132 in the vertical direction opposite to the first inner surface 131 with a gap of the fuel gas passage 3; including. Further, the inner surface 13 of the fuel gas flow channel 3 has a third inner surface 133 on one side in the lateral direction, and a fourth inner surface on the other side in the lateral direction facing the third inner surface 133 with a gap of the fuel gas flow channel 3 interposed therebetween. And 134. The first inner surface 131 and the second inner surface 132 are arranged in the vertical direction. The third inner surface 133 and the fourth inner surface 134 are arranged laterally.

  Therefore, the fuel gas flow path 3 has a first inner surface 131 and a second inner surface 132 sandwiching the first central surface, and a third inner surface 133 orthogonal to the first surface sandwiching and opposed the second central surface. The fuel gas passage 3 is surrounded by the inner surface 134, and the cross section of the fuel gas passage 3 is rectangular.

  FIG. 3 is a front view of the heating member 9. In the present embodiment, the heating member 9 is a rod-like member. As shown in FIG. 3, a plurality of first portions 91 of the heating member 9 are disposed in parallel with intervals in the lateral direction. Further, the second portion 92 of the heating member 9 is disposed so as to protrude from the first portion 91 of the heating member 9 to the secondary air flow path 6 in the longitudinal direction. That is, in FIG. 3, a plurality of heating members 9 are arranged side by side at predetermined intervals in the horizontal direction, and the heating members 9 may increase the number of heat transfer areas to increase the heat transfer area. . In order to increase the number of heating members 9 installed, a plurality of rows are arranged in a direction perpendicular to the flow direction of the fuel gas flow passage 3, an upstream side row and a downstream side row are provided in the axial direction, and the arrangement pitch is shifted to flow It may be arranged such that the pressure loss of the Furthermore, the heating members 9 may be arranged in a grid in the longitudinal direction and in the lateral direction.

  FIG. 4 is a front view of the flame stabilizing member 8. As shown in FIG. 2 and FIG. 4, the flame stabilizing member 8 is a rod-like member. The flame stabilizing member 8 is disposed closer to the fuel gas injection port 2 than the heating member 9. As shown in FIG. 4, in the present embodiment, the flame stabilizing members 8 have a longitudinal direction in the lateral direction, and a plurality of flame stabilizing members 8 are arranged in parallel at predetermined intervals in the longitudinal direction. Further, both end portions in the longitudinal direction of the flame holding member 8 are supported so as to allow thermal expansion, for example, by sleeves provided on the third inner surface 133 and the fourth inner surface 134 by a holding method (not shown) in the fuel gas passage 3 ing. A plurality of flame stabilizing members 8 may be arranged in parallel at predetermined intervals in the longitudinal direction with the longitudinal direction being the longitudinal direction, or may be disposed in a lattice.

  In the present embodiment, the number of heating members 9 is larger than the number of flame stabilizing members 8. The surface area of the entire first portion 91 of the heating member 9 is larger than the surface area of the entire flame stabilizing member 8.

  The inner surface 13 of the fuel gas passage 3 is parallel to the central axis AX of the fuel gas passage 3 toward the fuel gas injection port 2. Each of the first inner surface 131 and the second inner surface 132 has a constant distance between the first central surface and the first inner surface 131 toward the fuel gas injection port 2 in the axial direction, and also with the first central surface The distance to the second inner surface 132 is constant. Each of the third inner surface 133 and the fourth inner surface 134 has a constant distance between the second central surface and the third inner surface 133 toward the fuel gas injection port 2 in the axial direction, and the second central surface And the fourth inner surface 134 is constant. That is, the cross-sectional area of the fuel gas flow path 3 is constant toward the fuel gas injection port 2.

  FIG. 5 is an enlarged view of a part of the inner surface 13. The outlet cross-sectional areas of the primary air nozzle and the secondary air nozzle are selected so as to obtain a predetermined flow rate for the amount of air set to have a predetermined excess air ratio at the combustion furnace outlet. At this time, the secondary air nozzle is narrowed so that the cross-sectional area of the tip is smaller than that of the inlet, and the selected angle θ with respect to the central axis AX is approximately 0 ° to 30 °. It is designed. Since the cross-sectional area of the outlet portion of the secondary air nozzle 7 is narrowed so as to be smaller than the inlet portion, the flow velocity on the downstream side of the upstream side of the secondary air injection port 5 becomes faster. Secondary air Gb can be supplied. In the secondary air flow path 6, the secondary air Gb injected from the secondary air injection port 5 is disturbed so that the secondary air does not separate from the secondary air nozzle first inner surface 71 so that the flame does not become unstable. 30 degrees or less is preferable. In addition, when the angle is 30 ° or more, the angle to the inside of the furnace becomes large, and the amount of radiant heat received increases. In addition, when the outlet flow velocity is constant, the flow velocity on the inlet side becomes slower and the heat transfer coefficient decreases. Therefore, there is a concern about high temperature oxidation due to temperature rise of the nozzle and deformation associated therewith. In addition, designing the flow velocity to increase toward the tip also has the effect of preventing flashback. For this reason, it is preferable to limit within about 30 degrees.

  FIG. 6 is a view showing an example of a cross section orthogonal to the longitudinal direction of the first portion 91 of the heating member 9. As shown in FIG. 6, the cross section of the first portion 91 of the heating member 9 may be circular or elliptical.

  In the present embodiment, a protective film 17 is provided on the outer surface of the first portion 91 of the heating member 9 to protect the first portion 91 of the heating member 9 from pulverized coal. The protective film 17 functions as a wear resistant film.

  The heating member 9 desirably contains a large amount of copper in order to promote heat transfer. . The protective film 17 contains ceramics in order to prevent abrasion from pulverized coal.

  The protective film 17 is provided on the outer surface of the first portion 91 of the heating member 9 facing at least the upstream side of the fuel gas channel 3. FIG. 6 shows an example in which a protective film 17 is provided on the entire outer surface of the first portion 91 of the heating member 9.

  The protective film 17 may be made of ceramics such as alumina, silica, silicon carbide, zirconia, or a mixture of these. The protective film 17 is molded and fired so as to cover the outer peripheral surface of the supply member 9, and is fixed to the supply member 9 by bonding with a high temperature adhesive or by forming and inserting into a sleeve shape. Alternatively, they may be formed directly on the outer peripheral surface of the supply member 9 by thermal spraying. Further, the protective film 17 is not limited to ceramics, and high hardness metal such as high chromium cast iron can also be used. For example, the outside of the metal sleeve may be hardfacing.

  FIG. 7 is a view showing an example of a cross section orthogonal to the longitudinal direction of the first portion 91 of the heating member 9. As shown in FIG. 7, of the outer surface of the first portion 91 of the heating member 9, the region facing the upstream side of the fuel gas passage 3 includes a curved surface, and the region facing the downstream side of the fuel gas passage 3 is It may be a plane. Also in the example shown in FIG. 7, the protective film 17 is provided on the outer surface of the first portion 91 of the heating member 9 facing at least the upstream side of the fuel gas flow channel 3.

  FIG. 8 is a view showing an example of a cross section orthogonal to the longitudinal direction of the first portion 91 of the heating member 9. As shown in FIG. 8, the first portion 91 of the heating member 9 may have a shape in which the width increases toward the downstream of the fuel gas flow channel 3. As shown in FIG. 8, the cross section of the heating member 9 may be triangular. Also in the example shown in FIG. 8, the protective film 17 is provided on the outer surface of at least the first portion 91 of the heating member 9 facing the upstream side of the fuel gas passage 3. The flame stabilizing member 8 may have a cross section shown in FIG. 8 or may have a protective film 17.

  Further, the cross section orthogonal to the longitudinal direction of the flame stabilizing member 8 may have the same cross sectional shape as the heating member 9, or the flame stabilizing member 8 may have another cross sectional shape, but the cross sectional shape More preferably, the downstream side of is a flat surface. The shape may have a semicircular cross section, or may have a cross section as shown in FIG. In addition, a protective film 17 may be provided on the outer surface of the flame stabilizing member 8 facing at least the upstream side of the fuel gas flow path 3 to protect the flame stabilizing member 8 from pulverized coal.

  The flame stabilizing member 8 contains copper. The protective film 17 contains a ceramic. The protective film 17 of the flame stabilizing member 8 can be formed by a method similar to the material of the protective film 17 of the heating member 9.

  FIGS. 9 and 10 schematically show the flow of the fuel gas Ga around the first portion 91 of the heating member 9 or the third portion 81 of the flame stabilizing member 8 disposed in the fuel gas flow path 3. . Hereinafter, the flow of the fuel gas Ga around the third portion 81 of the flame stabilizing member 8 will be mainly described, but the flow of the fuel gas Ga around the first portion 91 is the same.

  As shown in FIG. 9, the flame stabilizing member 8 has a cross section in which the area facing the upstream side of the fuel gas flow path 3 includes the curved surface 15C and the area facing the downstream side of the fuel gas flow path 3 includes the flat surface 15D. The flat surface 15D is a front surface of the flame stabilizing member 8 facing the downstream side of the fuel gas flow path 3. The outer surface of the flame stabilizing member 8 is axisymmetric with respect to an imaginary line L1 parallel to the central axis AX.

  The fuel gas Ga flowing to the downstream side in the fuel gas flow channel 3 is separated in the vertical direction in the curved surface 15C of the flame stabilizing member 8 and flows in two directions. A portion of the fuel gas Ga flows along one side of the flame stabilizing member 8. A portion of the fuel gas Ga flows along the other side of the flame stabilizing member 8. After the fuel gas Ga flows along one side surface and the other side surface of the flame stabilizing member 8, a reverse flow area that flows so as to be caught on the plane 15 D side of the flame stabilizing member 8 is generated. The fuel gas Ga that has hit the curved surface 15C of the flame stabilizing member 8 flows into the plane 15D side of the flame stabilizing member 8 as a large reverse flow area without being separated from the flame stabilizing member 8. Therefore, in the front face 15D of the flame stabilizing member 8 as described later, the flame stabilizing state is surely realized.

  As shown in FIG. 10, the outer surface of the flame stabilizing member 8 is inclined such that the distance from the imaginary line L1 to the downstream side of the fuel gas passage 3 with respect to the imaginary line L1 parallel to the central axis AX increases. Of the first inclined surface 15A, the second inclined surface 15B inclined so that the distance between the first inclined surface 15A toward the fuel gas injection port 2 increases, and the flat surface 15D facing the downstream side of the fuel gas passage 3 And. The flat surface 15D is a front surface of the flame stabilizing member 8 facing the downstream side of the fuel gas flow path 3. The outer surface of the flame stabilizing member 8 is line symmetrical with respect to the imaginary line L1.

  In the example shown in FIG. 10, the external shape of the cross section of the flame stabilizing member 8 is a triangle (wedge shape). The corner portion (apex) 15 K between the first inclined surface 15 A and the second inclined surface 15 B faces the upstream side of the fuel gas flow channel 3. Further, the outer shape of the cross section of the flame stabilizing member 8 may not be a triangle (wedge shape), but may be a pseudo triangle having rounded corner portions, or a pseudo semicircle having curvature at the corner portions.

  The fuel gas Ga flowing to the downstream side in the fuel gas flow path 3 is separated vertically in the vertical direction at the corner portion 15K of the flame stabilizing member 8, and flows in two directions. A portion of the fuel gas Ga flows along the first inclined surface 15A. A portion of the fuel gas Ga flows along the second inclined surface 15B. After the fuel gas Ga flows along the first inclined surface 15A and the second inclined surface 15B, a reverse flow area that flows so as to be wound on the plane 15D side of the flame stabilizing member 8 is generated. The fuel gas Ga that has hit the corner 15K of the flame stabilizing member 8 flows into the plane 15D side of the flame stabilizing member 8 as a large reverse flow without being separated from the flame stabilizing member 8. Therefore, the decomposition of the pulverized coal into volatile components is promoted, and the flame holding state is reliably realized on the front surface 15D of the flame holding member 8.

  FIG. 11 is a view showing an arrangement example of the heating member 9 (first portion 91). FIG. 2 shows an example in which a single heating member 9 is disposed in the axial direction. As shown in FIG. 11, a plurality of first portions 91 of the heating member 9 may be arranged in the axial direction. FIG. 11 shows an example in which two are arranged in the axial direction. Note that three or more arbitrary numbers may be arranged in the axial direction.

  Further, in the example shown in FIG. 11, a first group GR1 including a plurality of first portions 91 spaced apart in the lateral direction and a second group disposed at a position different from the first group GR1 in the axial direction Group GR2 is arranged. In the lateral direction, the first portion 91 of the first group GR1 and the first portion 91 of the second group GR2 are disposed at different positions. That is, the first portions 91 are arranged in a staggered manner.

  The first portions 91 of the first group GR1 may be arranged at intervals in the vertical direction. The first portions 91 of the second group GR2 may be spaced apart in the longitudinal direction.

  The number of heating members 9 can be increased, the heat transfer area can be increased, and the fuel gas Ga can be reliably preheated. Furthermore, since the arrangement pitch is shifted in a staggered manner in the direction orthogonal to the flow direction of the fuel gas flow path 3, the pressure loss of the flow of the fuel gas Ga is not increased.

  Next, a method of burning the fuel gas Ga using the combustion burner 1 according to the present embodiment will be described. In the present embodiment, the combustion burner 1 generates a flame so as to internally hold a flame.

  The internal flame holding means a state in which a flame is generated in an internal space at a position upstream of the fuel gas injection port 2 of the fuel gas flow path 3 of the fuel nozzle 4 in the fuel gas flow direction. The internal space of the fuel gas flow path 3 is a space defined by the inner surface 13 and is a space facing the inner surface 13. In the internal flame holding, a flame is generated in a central longitudinal area or a lateral central area which is an area close to a plane including the central axis AX of the longitudinal surface or the lateral surface of the fuel gas injection port 2 including the central axis AX. State to be included.

  On the other hand, the external flame holding means a state in which a flame is generated around the fuel gas injection port 2 of the fuel nozzle 4. The external flame holding includes a state in which a flame is generated in the vicinity of the inner surface 13 of the fuel gas flow path 3 in the vicinity of the fuel gas injection port 2.

  In the present embodiment, the heating member 9 is heat transfer-heated so that the temperature becomes higher than the fuel gas Ga, and the fuel gas Ga is heated (preheated) by the first portion 91 of the heating member 9. The fuel gas Ga heated by the first portion 91 is supplied to the flame stabilizing member 8. The flame stabilizing member 8 is disposed at a position upstream of the fuel gas injection port 2 in the fuel gas flow direction. By supplying the heated fuel gas Ga to the flame holding member 8, a back flow is generated such that the fuel gas Ga is wound on the downstream surface of the fuel gas flow path 3 of the flame holding member 8, and ignition occurs. Flame is generated. Thereby, internal flame holding is realized. Further, the inner surface 13 of the fuel gas flow path 3 is parallel to the first central surface so that the cross-sectional area of the fuel gas flow path 3 becomes the same toward the fuel gas injection port 2. Also by this, internal flame stabilization is realized stably. Further, the flame stabilizing member 8 is disposed at a position other than the fuel gas injection port 2, and is disposed at a predetermined distance D upstream of the fuel gas flow path 3 from the fuel gas injection port 2. Also by this, internal flame stabilization is realized stably.

  In the present embodiment, the predetermined distance D is, for example, an appropriate value selected between 3.5 times and 5 times the length E of the axial cross section of the flame stabilizing member 8 in the fuel gas flow direction. The length E is a dimension of the flame stabilizing member 8 in a direction parallel to the central axis AX. If the predetermined distance D is shorter than 3.5 times, the transition to the external flame holding can be easily caused by the blowout of the secondary air Gb from the fuel gas injection port 2. For example, when the flame holding member 8 is provided in the vicinity of the fuel gas injection port 2 (near the outlet opening) and the predetermined distance D is small, it is easy to shift to the external flame holding. Also, if the predetermined distance D is longer than five times, the flame position becomes too upstream of the fuel gas channel 3 (the inlet side of the fuel gas channel 3), and the temperature of the inner surface 13 of the fuel gas channel 3 is excessive. It is not preferable because

FIG. 12 is a schematic view for explaining the combustion method of the fuel gas Ga according to the present embodiment. Fuel gas Ga in which pulverized coal and primary air are mixed is supplied to the fuel gas flow path 3 of the fuel nozzle 4 whose cross-sectional area decreases toward the fuel gas injection port 2, and from the fuel gas injection port 2 of the fuel nozzle 4 Fuel gas Ga is injected.

  Further, the secondary air Gb is supplied to the secondary air flow path 6 of the secondary air nozzle 7, and the secondary air Gb is jetted from the secondary air injection port 5 of the secondary air nozzle 7.

  The fuel gas Ga supplied to the fuel gas flow path 3 is heated (preheated) by the first portion 91 of the heating member 9 heated by the secondary air Gb, and then the fuel gas flow path 3 is heated from the first portion 91. Are also supplied to the flame stabilizing member 8 disposed downstream of the fuel gas flow path 3.

  By supplying the fuel gas Ga preheated by the heating member 9 to the flame holding member 8, the fuel gas Ga forms a reverse flow area in the vicinity of the flame holding member 8 disposed inside the fuel gas passage 3. The flames are generated by ignition. Thereby, internal flame holding is realized. In FIG. 12, the flame is described only in the vicinity of the fuel nozzle injection port 2, and the description of the flame extending to the combustion chamber 111 of the furnace 110 is omitted.

  The temperature of the fuel gas passage 3 is lower than the temperature of the secondary air passage 6. Further, the amount of oxygen inside the fuel gas flow passage 3 is smaller than the amount of oxygen in the secondary air Gb outside the fuel gas flow passage 3. In the case of the internal flame holding in which the flame is generated inside the fuel gas flow path 3, the flame is generated in the low temperature low oxygen space. Therefore, a rise in flame temperature can be suppressed, and the amount of NOx generation can be suppressed.

  Further, although the temperature of the fuel gas flow path 3 is low, the fuel gas Ga heated by the heating member 9 is supplied to the flame stabilizing member 8 to promote the ignition of the flame stabilizing member 8.

  FIG. 13 is a schematic view for explaining the combustion method of the fuel gas Ga by the combustion burner 1 according to the comparative example. The combustion burner 1 shown in FIG. 13 does not include the heating member 9 and the flame stabilizing member 8. In this case, an external flame holding is generated around the fuel gas injection port 2 of the fuel nozzle 4 in the flame. In the case of external flame holding, a flame is generated in a space in which the fuel gas Ga is mixed with the high-temperature, high-oxygen gas of the secondary air Gb, and therefore, the generation amount of NOx is likely to increase. The flame of FIG. 13 is described only in the vicinity of the fuel nozzle injection port 2 as in FIG. 12, and the description of the flame extending to the combustion chamber 111 of the furnace 110 is omitted.

In the present embodiment, since internal flame holding is realized, a rise in flame temperature is suppressed and the amount of NOx generation is suppressed. Also, in the case of internal flame holding, there is a high possibility that reducing substances such as HCN, CN and NH ₂ are produced. Even if NOx is produced by the reductant, the NOx is reduced to N ₂ . In internal flame holding, generation of reductant can be expected, which also suppresses the generation of NOx.

  If the position of the flame holding member 8 is too close to the fuel gas injection port 2 or the flame holding member 8 is disposed outside the fuel gas injection port 2, internal flame holding may not be realized stably. In the present embodiment, the flame holding member 8 is disposed on the upstream side of the fuel gas flow path 3 from the fuel gas injection port 2 so that the flame holding member 8 internally holds the flame inside the fuel gas flow path 3. It is placed at a distance D away. On the other hand, when the predetermined distance D is too long, a flame is generated on the upstream side of the fuel gas passage 3 (the inlet side of the fuel gas passage 3). As a result, the temperature of the fuel nozzle 4 may increase excessively. Therefore, the predetermined distance D is set to an optimum value so that internal flame holding can be stably realized while suppressing an excessive temperature rise of the fuel nozzle 4. The optimum value of the predetermined distance D can be determined by experiment, or can be determined by simulation based on the structure, size, and the like of the combustion burner 1.

  Further, in the present embodiment, the fuel gas flow path 3 has the same cross-sectional area toward the fuel gas injection port 2. If the fuel gas flow path 3 is narrowed in the vicinity of the fuel gas injection port 2, the flow velocity is increased, the internal flame holding can not be performed, and the external flame holding tends to occur. Conversely, if the fuel gas flow path 3 is expanded in the vicinity of the fuel gas injection port 2, the flow separates and circulation starts, and the swirl is caused by the circulation to hold the flame and shift to the external flame holding. In the present embodiment, since the fuel gas flow path 3 is not expanded or narrowed, internal flame holding can be stably realized.

  As described above, according to the present embodiment, the internal flame holding is realized, the ignition is stabilized, and the generation amount of NOx can be suppressed.

  Further, in the present embodiment, as described with reference to FIGS. 9 and 10, a reverse flow area is formed in which the fuel gas Ga heated by the heating member 9 flows in such a manner as to be caught in the plane 15D side of the flame holding member 8. By doing so, flame generation and flame stabilization in the plane 15D are promoted. Also by this, internal flame stabilization is realized stably.

  The cross-sectional shape of the first portion 91 of the heating member 9 may be the same as or different from the cross-sectional shape of the third portion 81 of the flame stabilizing member 8.

  Further, the surface area of the first portion 91 of the heating member 9 is made larger than the surface area of the flame stabilizing member 8, or as described with reference to FIG. 11, the first portions 91 are arranged in a plurality of rows in the axial direction. The heat transfer area can be increased by heating to increase the temperature to a higher temperature before the fuel gas Ga is supplied to the flame holding member 8 to improve the ignitability of the flame holding member 8. In addition, the temperature of the fuel gas Ga can be adjusted by adjusting the surface area of the first portion 91 of the heating member 9 or adjusting the number of the first portions 91 arranged in the axial direction.

  Further, as described with reference to FIG. 11, the first portions 91 are arranged in a staggered manner, thereby reducing the pressure loss and generating a low-speed flow of the fuel gas Ga around the first portions 91. Therefore, the fuel gas Ga can be efficiently heated.

Second Embodiment
The second embodiment will be described. In the following description, the component parts identical or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 14 is a front view showing an example of the flame stabilizing member 8 according to the present embodiment. Both ends of the flame stabilizing member 8 in the longitudinal direction are installed in the secondary air flow path 6 in the same manner as the heating member 9, and accordingly, the temperature of the flame stabilizing member 8 is transmitted from the secondary air Gb in the same manner as the heating member 9. It is heated by heat.

  Further, in the present embodiment, the flame stabilizing member 8 includes the third portion 81 and the fourth portion 82 in the same manner as the heating member 9. The third portion 81 is disposed upstream of the fuel gas injection port 2 in the flow of the fuel gas passage 3. Since the fourth portion 82 is disposed in the secondary air flow path 6, the temperature of the flame stabilizing member 8 is raised by the heated secondary air Gb.

  In the same manner as the heating member 9, the heat holding temperature of the flame holding member 8 is raised to a temperature higher than that of the fuel gas Ga. The fuel gas Ga is heated by the heating member 9 and then supplied to the flame stabilizing member 8. The flame holding member 8 causes the fuel gas Ga to further increase in temperature by the flame holding member 8 when backflow is caused to flow so as to cause the fuel gas Ga to be caught in the downstream surface of the fuel gas flow path 3. The decomposition of H 2 to its volatile constituents is promoted and it is easily ignited to produce a flame. Thereby, internal flame stabilization is realized more stably.

Third Embodiment
A third embodiment will be described. In the following description, the component parts identical or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 15 is a view showing a part of the heating member 9 or the flame stabilizing member 8 according to the present embodiment. As shown in FIG. 15, the dimension of the axial second portion 94 may be larger than the dimension of the first portion 91 while not obstructing the flow of the secondary air Gb. Thereby, the surface area of the second portion 94 is larger than the cross-sectional area orthogonal to the longitudinal direction of the first portion 91. Accordingly, when heat is transferred from the second portion 94 to the first portion 91, there is no location where the heat transfer resistance becomes extremely greater than the other, and heat transfer is efficiently performed. Moreover, in the secondary air flow path 6, the heat transfer area between the second portion 94 and the secondary air Gb is increased, so that the first portion 91 can be heated more efficiently. The dimension of the second portion 94 in the lateral direction (or longitudinal direction) may be larger than the dimension of the first portion 91 while preventing the flow of the secondary air Gb.

Fourth Embodiment
A fourth embodiment will be described. In the following description, the component parts identical or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 16 is a view showing a part of the heating member 9 according to the present embodiment. As shown in FIG. 16, in the first portion 93, the dimension in the axial direction orthogonal to the longitudinal direction of the heating member 9 may be larger than the dimension in the other direction (lateral direction in FIG. 16). As a result, the fuel gas Ga flowing in the axial direction in the fuel gas passage 3 can increase the heat transfer area so as to be in contact with the first portion 91 for a long time without increasing the pressure loss in the passage. Therefore, the fuel gas Ga is efficiently heated.

FIG. 17 is a view showing a part of the heating member 9 according to the present embodiment. As shown in FIG. 17, in the first portion 93, the dimension in the axial direction orthogonal to the longitudinal direction of the heating member 9 is larger than the dimension in the other direction (lateral direction in FIG. 17), and further in the other direction (FIG. 16). (A plurality of directions) may be arranged. Thus, the fuel gas Ga flowing in the axial direction can increase the heat transfer area in contact with the first portion 93 without increasing the pressure loss of the flow passage, and the fuel gas Ga is more efficiently heated. Ru.
A protective film 17 may be provided on both the end of the heating member 9 facing the upstream side of the fuel gas flow passage 3 and the end of the heating member 9 facing the downstream side of the fuel gas flow passage 3. FIG. 17 shows an example in which a protective film 17 is provided in the first portion 93 of the plurality of heating members 9 arranged.

Fifth Embodiment
A fifth embodiment will be described. In the following description, the component parts identical or equivalent to those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 18 is a side view showing an example of the heating member 9 or the flame stabilizing member 8 according to the present embodiment. FIG. 19 is a perspective view showing an example of a heating member or a flame stabilizing member according to the present embodiment. Hereinafter, although it demonstrates as a heating member 9, it is the same also as the flame-holding member 8 temperature-increased by the secondary air Gb.

  In the present embodiment, the heating member 9 includes a fifth portion 95 disposed in the fuel gas passage 3 and a sixth portion 96 disposed in the secondary air passage 6 and is heated by the secondary air Gb. Ru.

That is, in the present embodiment, the cross-sectional shape of the fifth portion 95 of the heating member 9 is different in the longitudinal direction (vertical direction in FIG. 18). When the length of the fifth portion 95 of the heating member 9 in the longitudinal direction (longitudinal direction in FIG. 18) is long, the heat transfer distance from the sixth portion 96 is long, so the fifth portion 95 has a temperature distribution. It is to improve the ease.
The fuel gas Ga heated by the fifth portion 95 of the heating member 9 heated by the secondary air Gb is supplied to the flame holding member 8. As a result, the fifth portion 95 is preheated to promote ignition and flame generation in the flame stabilizing member 8. Also, since the sixth portion 96 is formed in a streamlined shape and does not impede the flow of the secondary air Gb, it is not necessary to increase the pressure loss.

  In the example shown in FIGS. 18 and 19, the surface area of the axially extending sixth portion 96 is larger than the cross-sectional area orthogonal to the longitudinal direction of the fifth portion 95. Thereby, in the secondary air flow path 6, the heat transfer area in which the sixth portion 96 and the secondary air Gb contact is increased, so that the heat input to the fifth portion 95 can be secured. The fifth portion 95 can be efficiently heated. In the other direction (lateral direction in FIG. 19) orthogonal to the longitudinal direction and axial direction of the fifth portion 95 of the heating member 9, the lateral dimension of the sixth portion 96 is greater than the lateral dimension of the fifth portion 95 The surface area of the sixth portion 96 may be further increased by increasing it.

  Moreover, in the example shown in FIG.18 and FIG.19, the 5th part 95 is a rod-shape from which a cross-sectional area differs in a longitudinal direction. The fifth portion 95 has a first portion 9A near the first central surface of the fuel gas passage 3 in the cross section of the fuel gas passage 3 and a first portion 9A farther from the first central surface than the first portion 9A. And 2 sites 9B. The first portion 9A has a cross-sectional area perpendicular to the longitudinal direction larger than that of the second portion 9B, that is, 9A has a thicker shape. It is further preferable that the cross-sectional area orthogonal to the longitudinal direction gradually increases from the second portion 9B toward the first portion 9A.

  On the other hand, the second portion 9B is located closer to the sixth portion 96 than the first portion 9A. In the fifth portion 95, after the second portion 9B is heated, the first portion 9A is heated. Here, as the heat transfer distance is farther from the second portion 9B, the cross-sectional area perpendicular to the longitudinal direction to the first portion 9A increases. For this reason, since the heat transfer distance is longer than that of the second portion 9B, the heat transfer to the first portion 9A which is hard to be transferred is secured, and the heat transfer characteristic to the first portion 9A can be improved. By making the cross-sectional area of the first portion 9A larger than that of the second portion 9B in a stepwise manner, the temperature of the fifth portion 95 can be made uniform.

  Accordingly, when the heat is transferred from the second portion 9B to the first portion 9A via the sixth portion 96 from the secondary air Gb, the longitudinal cross-sectional area gradually increases, so the power is transmitted from the second portion 9B. The temperature of the first portion 9A having a long thermal distance can be raised to a temperature close to the temperature of the second portion 9B.

  Furthermore, the contact heat transfer area between the fuel gas Ga and the fifth portion 95 (first portion 9A) at the central portion of the fuel gas passage 3 near the first central surface is increased. The heat transfer characteristic between the portion 95 and the first portion 9A is improved, and the temperature of the fuel gas Ga near the first central surface is raised to a higher temperature, and the center of the fuel gas passage 3 near the first central surface I will ignite surely in the part. Thereby, internal flame stabilization is realized more stably.

DESCRIPTION OF SYMBOLS 1 combustion burner 2 fuel gas injection port 3 fuel gas flow path 4 fuel nozzle 5 secondary air injection port 6 secondary air flow path 7 secondary air nozzle 8 flame holding member 9 heating member 13 inner surface 15A first inclined surface 15B second Inclined surface 15C Curved surface 15D Flat surface 17 Protective film 20 Auxiliary air injection port 21 Auxiliary air passage 22 Auxiliary air nozzle 71 Secondary air nozzle first inner surface 72 Secondary air nozzle second inner surface 81 Third portion 82 Fourth portion 91 First portion Part 92 Second part 93 First part 94 Second part 96 Sixth part 100 Boiler 110 Fire furnace 111 Combustion chamber 112 Flue 113 Exhaust gas flow path 114 Air heater 120 Combustion device 121 Pulverized coal supply device 122 Air supply device 123 Pulverized coal machine 124 Pulverized coal supply pipe 125 Blower 126 Air box 127 Air supply pipe 131 First inner surface 132 Second inner surface 133 Third inner surface 134 Fourth inner surface 140 steam generator 141 superheater 142 reheater 143 economizer AX center axis D predetermined distance Ga fuel gas Gb secondary air Gd auxiliary air P1 first position P2 second position θ angle

Claims (14)

A fuel nozzle having a fuel gas injection port for injecting a fuel gas in which carbon-containing solid fuel and primary air are mixed, and a fuel gas flow path including an end provided with the fuel gas injection port;
A secondary air nozzle having a secondary air injection port disposed around the fuel gas injection port and injecting secondary air, and a secondary air flow path including an end provided with the secondary air injection port; ,
A flame holding member disposed in the fuel gas flow path upstream of the fuel gas from the fuel gas injection port;
A heating member disposed upstream of the fuel gas passage in the fuel gas passage than in the flame holding member;
The heating member includes a first portion disposed in the fuel gas flow path and a second portion disposed in the secondary air flow path, and the heating member is heated by the secondary air.
The flame stabilizing member includes a third portion disposed in the fuel gas flow path and a fourth portion disposed in the secondary air flow path, and the flame stabilizing member is heated by the secondary air ,
Combustion burner. The fuel gas flow channel has a first inner surface with respect to a first central surface including the central axis of the fuel gas flow channel and a second central surface orthogonal to the first central surface and including the central axis, A second inner surface opposite to the first inner surface sandwiching the first central surface, a third inner surface orthogonal to the first inner surface, and a second inner surface opposite to the third inner surface sandwiching the second central surface Surrounded by 4 inner surfaces,
The first inner surface and the second inner surface have the same distance to the first central surface,
The third inner surface and the fourth inner surface have the same distance to the second central surface,
The combustion burner according to claim 1. The angle between the inner surface of the secondary air nozzle of the secondary air flow path and the first center plane is 0 ° or more and 30 ° or less.
The combustion burner according to claim 2. A plurality of the first portions of the heating member are disposed at predetermined intervals in a direction orthogonal to a central axis of the fuel gas flow channel.
The combustion burner according to any one of claims 1 to 3. The heating member includes a first group including a plurality of first portions spaced apart in a first axial direction orthogonal to a central axis of the fuel gas flow path, and a direction parallel to the central axis, And a second group disposed at a position different from the first group,
The first portion of the first group and the first portion of the second group are disposed at different positions with respect to the first axial direction.
The combustion burner according to any one of claims 1 to 3. The surface area of the second portion of the heating member is greater than the cross-sectional area orthogonal to the longitudinal direction of the first portion,
The combustion burner according to any one of claims 1 to 5. It has a protective film provided on the outer surface of at least one of the heating member and the flame holding member facing at least the upstream side of the fuel gas flow path and protecting at least one of the heating member and the flame holding member from pulverized coal. ,
The combustion burner as described in any one of Claims 1-6. The outer surface of the flame stabilizing member is inclined with respect to a virtual line parallel to the central axis of the fuel gas flow path such that the distance to the virtual line increases in a direction toward the downstream side of the fuel gas flow path And a second inclined surface which is inclined such that a distance to the first inclined surface increases in a direction toward the downstream side of the fuel gas channel.
The combustion burner as described in any one of Claims 1-7. The first portion is rod-shaped,
The first portion is a first portion located at an intermediate position between one end portion and the other end portion of the first portion, and each of the one end portion and the other end portion of the first portion and the second portion. And a second part to be connected,
The surface area of the second portion is larger than the cross-sectional area orthogonal to the longitudinal direction of the first portion,
In a cross section orthogonal to the longitudinal direction of the first portion, a cross section of the first portion is larger than a cross section of the second portion,
A combustion burner according to any one of the preceding claims. The first portion is rod-shaped, and in a cross section orthogonal to the longitudinal direction of the first portion, the cross-sectional area gradually increases from the second portion toward the first portion.
The combustion burner according to claim 9. The third portion is rod-shaped,
The third portion includes a first portion located at an intermediate position between one end portion and the other end portion of the third portion, and each of the one end portion and the other end portion of the third portion and the fourth portion. And a second part to be connected,
The surface area of the fourth portion is larger than the cross-sectional area orthogonal to the longitudinal direction of the third portion,
In the cross section orthogonal to the longitudinal direction of the third portion, the cross sectional area of the first portion is larger than the cross sectional area of the second portion,
A combustion burner according to any one of the preceding claims. The third portion is rod-shaped, and in a cross section orthogonal to the longitudinal direction of the third portion, the cross-sectional area gradually increases from the second portion toward the first portion.
A combustion burner according to claim 11.   The boiler provided with the combustion burner as described in any one of Claims 1-12. The fuel gas passage of the fuel nozzle toward the fuel gas injection port, the supplied fuel gas that is a mixture of carbon-containing solid fuel and primary air, injecting the fuel gas from the fuel gas injection port of the fuel nozzle When,
The secondary air is supplied to the secondary air flow path of the secondary air nozzle, and the secondary air is injected from the secondary air injection port of the secondary air nozzle disposed around the fuel gas injection port. And
The first portion includes a first portion disposed in the fuel gas flow path and a second portion disposed in the secondary air flow path, and the second portion is heated by the secondary air. Preheating the fuel gas with a heating member, the temperature of which is increased;
A third portion disposed downstream of the fuel gas flow passage downstream of the fuel gas flow passage with respect to the first portion and in the fuel gas flow passage upstream of the fuel gas injection port and disposed in the fuel gas flow passage; A flame stabilizing member having a fourth portion disposed in the secondary air flow path, wherein the third portion is heated by heating the fourth portion with the secondary air; Supplying the preheated fuel gas;
Internal flame holding state in the fuel gas flow path by the flame holding member;
Fuel gas combustion method including:

Images