Burner and boiler having the same

Abstract

To provide a burner capable of suppressing thermal shock and vapor lock even when liquefied gas fuel is used.SOLUTION: The burner 21 includes a nozzle body 60 for injecting liquefied ammonia fuel L toward the furnace 11, and an outer pipe A1 and an 64c for guiding outside air A2 having a temperature lower than that of combustion air 60c flowing outside the nozzle body 60 along an outer peripheral surface of the nozzle body 60. The nozzle body 60 includes an inner pipe side 60b and an outer pipe side 60b provided so as to cover the periphery of the inner pipe side 60c, and the outside air A2 is guided between the inner pipe side 60b and the outer pipe side 60c.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a burner that burns a liquefied gas fuel, such as liquid ammonia fuel, and a boiler equipped with the burner. [Background technology]

[0002] Large boilers, such as power generation boilers, have a hollow furnace installed vertically, with multiple burners disposed on the furnace wall. Large boilers also have a flue connected vertically above the furnace, with a heat exchanger disposed in the flue for generating steam. The burner injects a mixture of fuel and air (oxidizing gas) into the furnace, forming a flame, generating combustion gas that flows down the flue. A heat exchanger is installed in the area where the combustion gas flows, and superheated steam is generated by heating water or steam flowing through the heat transfer tubes that make up the heat exchanger.

[0003] BACKGROUND ART A known burner used in a boiler has a configuration in which combustion air flows around the outer periphery of a nozzle that injects fuel into a furnace (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-68510 Summary of the Invention [Problem to be solved by the invention]

[0005] Burners that use liquid fuels such as diesel or heavy oil use a burner gun system in which the nozzle tip is inserted into the furnace when the burner is ignited and is pulled out of the furnace when the burner is extinguished. This is because if the burner is operated for a long period of time with the nozzle tip inserted into the furnace when the burner is extinguished, the nozzle tip will become very hot due to radiant heat from inside the furnace and will be burned.

[0006] On the other hand, when the burner is extinguished, it should be installed in the same position as when the burner is ignited, and if the burner gun method is not used, the nozzle tip will need to be cooled to prevent damage from radiant heat from inside the furnace.

[0007] As shown in Patent Document 1, the combustion air flowing around the nozzle tip is used as a cooling medium. However, since the combustion air is preheated to 300°C or higher (for example, about 330°C) to increase thermal efficiency, the following problems arise when liquid ammonia fuel (liquefied gas fuel) is used as the fuel.

[0008] (1) Thermal shock When liquid ammonia fuel is sprayed from a nozzle, the temperature of the nozzle tip drops to below freezing due to the large latent heat of vaporization of ammonia. Therefore, if cooled with combustion air (for example, about 330°C), the nozzle tip exceeds 330°C when liquid ammonia fuel is not being sprayed, and when liquid ammonia is sprayed, the nozzle tip drops to below freezing in an instant, and there is a risk of cracks occurring in the nozzle tip due to the thermal shock caused by a temperature difference of more than 330°C.

[0009] (2) Vapor lock Ammonia has a boiling point of -33.3°C at atmospheric pressure and is a substance that vaporizes easily. When the nozzle is cooled with combustion air (for example, at about 330°C) to prevent damage from radiant heat when the burner is not in use, the nozzle will heat up to about 330°C. As a result, the liquid ammonia fuel supplied to the nozzle is heated and begins to vaporize, causing vapor lock inside the nozzle (the ammonia expands in volume as it vaporizes, causing a sudden increase in pressure loss and making it difficult to inject the liquid ammonia fuel).

[0010] The present disclosure has been made in consideration of these circumstances, and aims to provide a burner and a boiler equipped with the same that can suppress thermal shock and vapor lock even when using liquefied gas fuel. [Means for solving the problem]

[0011] A burner according to one aspect of the present disclosure includes a nozzle body that injects liquefied gas fuel toward a furnace, and a cooling fluid supply means that guides a cooling fluid having a lower temperature than the fluid flowing outside the nozzle body along the outer peripheral surface of the nozzle body.

[0012] A boiler according to one aspect of the present disclosure includes the burner described above. [Effects of the Invention]

[0013] Even when liquefied gas fuel is used, thermal shock and vapor lock can be suppressed. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic configuration diagram illustrating a boiler according to an embodiment of the present disclosure. [Figure 2] 1 is a cross-sectional view of a burner according to an embodiment of the present disclosure; [Figure 3] FIG. 3 is a side cross-sectional view of the burner of FIG. 2. [Figure 4] FIG. 4 is a side cross-sectional view showing the state in which the oil burner gun is installed in FIG. 3. [Figure 5] FIG. 10 is a side cross-sectional view of the burner installed in the air nozzle compartment. [Figure 6] FIG. 1 is a side cross-sectional view of a burner installed in an air nozzle compartment equipped with two stages of air nozzles. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to this embodiment, and when there are multiple embodiments, it also includes configurations that combine the embodiments. In the following description, "up" and "upper" refer to the upper side in the vertical direction, and "lower" and "lower" refer to the lower side in the vertical direction, and the vertical direction is not precise and may include errors.

[0016] FIG. 1 shows a boiler 10 according to this embodiment that is capable of burning liquid ammonia (NH3) fuel. The boiler 10 of this embodiment is a boiler that can burn liquid ammonia fuel, pulverized fuel made by pulverizing solid fuel (coal or biomass fuel), or oil fuel such as heavy oil using a burner, and exchange the heat generated by this combustion with feedwater or steam to generate superheated steam.

[0017] The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 has a hollow rectangular cylindrical shape and is installed vertically. The furnace wall 101 that forms the inner wall surface of the furnace 11 is composed of a plurality of heat transfer tubes and fins that connect the heat transfer tubes together, and recovers the heat generated by the combustion of pulverized fuel by heat exchange with water and steam circulating inside the heat transfer tubes, while suppressing the temperature rise of the furnace wall 101.

[0018] The combustion device 20 is installed in the lower region of the furnace 11. In this embodiment, the combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, and 21F (hereinafter, when these burners are not to be distinguished, they will be simply referred to as "burners 21") attached to the furnace wall 101. The burners 21 are arranged at equal intervals in the furnace width direction along the furnace wall 101 (for example, they are arranged in the furnace width direction so as to face each other on the opposing furnace walls 101 for opposed combustion), and are arranged in multiple stages along the vertical direction. The shape of the furnace, the number of burner stages, the number of burners per stage, the arrangement of the burners, etc. are not limited to this embodiment.

[0019] Burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to a plurality of mills (pulverizers) 31A, 31B, 31C, 31D, 31E, and 31F (hereinafter, when these mills are not distinguished, they will be simply referred to as "mills 31") via a plurality of pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F, respectively (hereinafter, when these mills are not distinguished, they will be simply referred to as "mills 31"). Mill 31 is, for example, a vertical roller mill having a rotatable grinding table (not shown) supported therein and a plurality of grinding rollers (not shown) supported above the grinding table so that they can rotate in conjunction with the rotation of the grinding table. The solid fuel pulverized by the cooperation of the grinding rollers and the grinding table is transported to a classifier (not shown) provided in mill 31 by primary air (carrier gas, oxidizing gas) supplied to mill 31. The classifier separates the pulverized fuel into pulverized fuel having a particle size smaller than that suitable for combustion in the burner 21 and coarse pulverized fuel having a particle size larger than that. The pulverized fuel passes through the classifier and is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. The coarse pulverized fuel that does not pass through the classifier falls onto the grinding table inside the mill 31 under its own weight and is re-ground.

[0020] At least some of the burners 21A, 21B, 21C, 21D, 21E, and 21F are ammonia-fired burners to which liquid ammonia fuel is supplied. In this case, the other burners 21A, 21B, 21C, 21D, 21E, and 21F are pulverized coal-fired burners. The ammonia-fired burners are not supplied with pulverized fuel from the mill 31, but are supplied with liquid ammonia fuel from the liquid ammonia supply source 50.

[0021] An air register 23 is provided outside the furnace 11 at the installation position of the burner 21, and one end of an air duct 24 is connected to the air register 23. A forced draft fan (FDF) 32 is connected to the other end of the air duct 24. The air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24 and is supplied to the burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas) and introduced into the furnace 11.

[0022] The combustion gas passage 12 is connected to the vertical upper part of the furnace 11. The combustion gas passage 12 is provided with superheaters 102A, 102B, and 102C (hereinafter, when there is no need to distinguish between these superheaters, they will simply be referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter, when there is no need to distinguish between these reheaters, they will simply be referred to as "reheater 103"), and a coal economizer 104 as heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated in the furnace 11 and feedwater or steam circulating inside each heat exchanger. Note that the arrangement and shape of each heat exchanger are not limited to those shown in FIG. 1.

[0023] A flue 13 is connected to the downstream side of the combustion gas passage 12, and discharges the combustion gas whose heat has been recovered by the heat exchanger. An air preheater (air heater) 42 is provided between the flue 13 and the air duct 24, and heat is exchanged between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13, heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21, thereby recovering further heat from the combustion gas after heat exchange with water and steam.

[0024] Furthermore, a denitration device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitration device 43 supplies a reducing agent, such as ammonia or urea water, which has the effect of reducing nitrogen oxides, to the combustion gas flowing through the flue 13, and promotes the reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent by the catalytic action of a denitration catalyst provided in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas.

[0025] A gas duct 41 is connected to the flue 13 downstream of the air preheater 42. The gas duct 41 is provided with environmental equipment such as a dust collector 44, such as an electrostatic precipitator, that removes ash and the like from the combustion gas, and a desulfurization equipment 46 that removes sulfur oxides, as well as an induced draft fan (IDF) 45 that guides the exhaust gas to these environmental equipment. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas treated in the environmental equipment is discharged to the outside of the system as exhaust gas.

[0026] When the boiler 10 is performing mono-combustion of pulverized fuel (or co-combustion with ammonia fuel), the multiple mills 31 are driven, and pulverized and classified pulverized fuel is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. Secondary air heated by the air preheater 42 is supplied to the burner 21 from the air duct 24 via the wind box 23. The burner 21 blows a pulverized fuel mixture, which is a mixture of pulverized fuel and primary air, into the furnace 11, and also blows secondary air into the furnace 11. The pulverized fuel mixture blown into the furnace 11 ignites and reacts with the secondary air to form a flame. A flame is formed in the lower region of the furnace 11, and high-temperature combustion gas rises within the furnace 11 and flows into the combustion gas passage 12. In this embodiment, air is used as the oxidizing gas (primary air, secondary air), but the oxidizing gas may have a higher or lower oxygen content than air, and stable combustion can be achieved in the furnace 11 by adjusting the ratio of the amount of oxygen to the amount of fuel supplied within an appropriate range.

[0027] Additionally, above the mounting position of the burners 21 in the furnace 11, a plurality of additional air ports (AA ports) 25 are provided for supplying additional air for combustion (AA) into the furnace 11. The additional air ports 25 are connected to the ends of additional air ducts (AA ducts) 26 branching off from the air duct 24, and a portion of the air supplied from the forced draft fan 32 can be supplied to the additional air ports 25 via the additional air ducts 26 as additional air for combustion.

[0028] In region A (corresponding to the installation range of the wind box 23 in the height direction) inside the furnace 11 shown in Fig. 1, a flame is formed by combustion of a mixture of primary air, liquid ammonia fuel and / or pulverized fuel, and secondary air. Here, the air ratio in region A is set to be 1 or less, specifically, the amount of air supplied to the burner 21 (the total amount of primary air and secondary air) is set to be less than the theoretical amount of air relative to the amount of fuel supplied to the burner 21. By doing so, regions A and B (regions between the top of the burner 21 and the bottom of the additional air port 25) inside the furnace 11 become reducing atmospheres, and nitrogen oxides (NOx) generated by combustion are reduced inside the furnace 11. Thereafter, in region C (region above the bottom of the additional air port 25), additional combustion air is supplied from the additional air port 25 to the combustion gas in which NOx has been reduced, completing the combustion. However, the amount of NOx generated is reduced by the reduction effect in regions A and B.

[0029] The combustion gas that has flowed into the combustion gas passage 12 exchanges heat with water and steam in a superheater 102, a reheater 103, and an economizer 104 arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in a denitration device 43, and the gas exchanges heat with primary air and secondary air in an air preheater 42, and is then discharged into the gas duct 41, where ash and the like are removed in a dust collector 44, and sulfur oxides are removed in a desulfurization device 46, and the gas is then discharged to the outside of the system from a chimney 47. Note that the arrangement of the heat exchangers in the combustion gas passage 12 and the arrangement of the devices from the flue 13 to the gas duct 41 with respect to the combustion gas flow do not necessarily have to be in the order described above.

[0030] The boiler 10 is provided with a liquid ammonia supply source 50. Ammonia is stored in liquid form as an ammonia fuel in the liquid ammonia supply source 50. The liquid ammonia is supplied from the liquid ammonia supply source 50 to each burner 21.

[0031] The control unit is composed of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and computer-readable storage media. A series of processes for realizing various functions is stored in, for example, a storage medium in the form of a program. The CPU reads this program into RAM and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0032] A burner 21 in which liquid ammonia fuel is used as the injected fuel is shown in Figures 2 and 3. Figure 2 is a cross-sectional view of the burner 21 as viewed from above, and Figure 3 is a cross-sectional view of the burner 21 as viewed from the side.

[0033] As shown in Fig. 2, the burner 21 injects (sprays) liquefied ammonia fuel L toward the furnace 11. The burner 21 is provided in an oil nozzle compartment 61 in which an oil burner gun 68 is installed as shown in Fig. 4. As shown in Fig. 2, the burner 21 includes a main pipe 64 and a plurality of nozzle bodies 60 branching off from the main pipe 64. The main pipe 64 is provided to extend horizontally so as to penetrate a side wall 62a of the wind box 62 from the outside. The oil burner gun 68 is used when burning fuels other than liquefied ammonia fuel L, but by switching the fuel supply line, the oil burner gun 68 may also be used when burning liquefied ammonia fuel L.

[0034] The nozzle bodies 60 extend in a direction perpendicular to the main pipe 64 and are arranged in parallel at predetermined intervals. Each nozzle body 60 has a smaller diameter than the main pipe 64. Although there are eight nozzle bodies 60 in FIG. 2, this is not limitative and the number can be determined appropriately.

[0035] The tip 60a of each nozzle body 60 is arranged facing the inside of the furnace 11. The tip 60a of each nozzle body 60 is provided so as to be located inside a combustion air nozzle 66 connected to the furnace 11 side of the wind box 62.

[0036] Combustion air A1 is supplied into the wind box 62. The combustion air A1 is preheated by the air preheater 42 (see FIG. 1) to a temperature of 300°C or higher (for example, approximately 330°C). The combustion air A1 flows around each nozzle body 60 and then is blown into the furnace 11. The combustion air A1 prevents damage to the tip 60a of each nozzle body 60 due to radiant heat from the furnace 11, which is heated to approximately 1300°C.

[0037] The main pipe 64 has a double pipe structure composed of an inner pipe 64b and an outer pipe (cooling fluid supply means) 64c surrounding the inner pipe 64b. Liquefied ammonia fuel L is introduced into the inner pipe 64b from a liquid ammonia supply source 50 (see FIG. 1). Outside air A2 at room temperature (outside air temperature) is introduced into the outer pipe 64c. As a result, the outside air (cooling fluid) A2 is introduced along the outer periphery of the inner pipe 64b. It is preferable to ensure that the flow velocity of the outside air (cooling fluid) A2 flowing through the gap between the outer pipe 64c and the inner pipe 64b is 1 m / s or more, and preferably 15 m / s or more and 25 m / s or less.

[0038] When outside air A2 is supplied as a cooling medium, the outside air A2 discharged from the nozzle body 60 may lower the temperature of the combustion air A1 and cause a decrease in thermal efficiency. Therefore, by setting the gap between the inner pipe 64b and the outer pipe 64c to a predetermined dimension or less and increasing the flow rate of the outside air A2, cooling can be performed with a small amount of outside air A2.

[0039] Each nozzle body 60 has a double-pipe structure made up of an inner pipe 60b and an outer pipe (cooling fluid supply means) 60c that surrounds the inner pipe 60b. The inner pipe 60b of each nozzle body 60 communicates with the inner pipe 64b of the main pipe 64, and liquefied ammonia fuel L is introduced therethrough. The outer pipe 60c of each nozzle body 60 communicates with the outer pipe 64c of the main pipe 64, and outside air A2 is introduced therethrough. The outer pipe 60c extends to the tip of the inner pipe 60b, and therefore, outside air A2 is introduced along the outer periphery of the inner pipe 60b to the tip.

[0040] 4, the nozzle bodies 60 are arranged in two rows, one above the other, inside the combustion air nozzle 66. However, the arrangement of the nozzle bodies 60 is not limited to two rows, one above the other, and may be one row or three or more rows.

[0041] An oil-air nozzle 70 is provided approximately at the center inside the combustion air nozzle 66. Each nozzle body 60 in the upper row is provided above the oil-air nozzle 70, and each nozzle body 60 in the lower row is provided below the oil-air nozzle 70.

[0042] The burner 21 described above is used as follows. When liquefied ammonia fuel L is combusted using the nozzle body 60, the liquefied ammonia fuel is supplied from the liquid ammonia supply source 50 to the inner pipe 64b of the main pipe 64. At this time, outside air A2 is supplied to the outer pipe 60c of the main pipe 64. As a result, the liquefied ammonia fuel L passes through the inner pipe 60b of the nozzle body 60 and is injected into the furnace 11, and the outside air A2 flows along the outer periphery of the inner pipe 60b.

[0043] 4 to the outside of the furnace, the oil burner gun 68 can be prevented from being damaged by radiant heat from the furnace 11. On the other hand, the nozzle body 60 is fixed in position and faces the furnace 11 regardless of the state of use (ignition state or extinguishing state). That is, the nozzle body 60 faces the furnace 11 whether it is ignition or extinguishing. During ignition when liquefied ammonia fuel L is flowing through the inner pipe 60b of the nozzle body 60, the inner pipe 60b is cooled by the liquefied ammonia fuel L, so there is no risk of damage by radiant heat. However, during extinguishing when the nozzle body 60 is stopped without flowing liquefied ammonia fuel L, there is a risk of thermal damage because cooling by the liquefied ammonia fuel L is not performed. Therefore, even when the nozzle body 60 is extinguished, the outside air A2 continues to flow from the outer tube 60c. This makes it possible to suppress thermal damage to the nozzle body 60. Furthermore, even when the liquefied ammonia fuel L starts to flow into the inner tube 60b of the nozzle body 60 at the time of re-ignition, it is possible to suppress thermal shock and vapor lock.

[0044] The above-described embodiment has the following advantages. In order to cool the outer peripheral surface of the nozzle body 60 that injects the liquefied ammonia fuel L, outside air A2, which has a lower temperature than the combustion air A1, is introduced along the outer peripheral surface of the nozzle body 60. Because the outside air A2 has a lower temperature than the combustion air A1 flowing on the outside, the temperature difference between the outside air A2 and the liquefied ammonia fuel L flowing through the inner tube of the nozzle body 60 can be reduced, making it possible to suppress thermal shock and vapor lock in the nozzle body 60. This improves durability and enables stable fuel injection.

[0045] The nozzle body 60 has a double-pipe structure consisting of an inner pipe 60b and an outer pipe 60c, and the outside air A2 is guided between the inner pipe 60b and the outer pipe 60c. This allows the outside air A2 to flow stably along the outer periphery of the inner pipe 60b.

[0046] Because the nozzle body 60 is branched into multiple parts from the main pipe 64 and arranged in parallel, the diameter of each of the branched nozzle bodies 60 is small. This reduces the heat capacity of each nozzle body 60, resulting in larger temperature changes and making it easier for the liquefied ammonia fuel L flowing inside the nozzle body 60 to evaporate. Even with this configuration, the outside air A2 is guided along the outer periphery of the inner pipe 60b of each nozzle body 60, making it possible to suppress thermal shock and vapor lock.

[0047] The nozzle body 60 is configured to remain positioned facing the furnace 11 even when the system is stopped (fire extinguished) and liquefied ammonia fuel L is not flowing from the nozzle body 60. In other words, the burner gun method of retracting the nozzle body 60 when the system is stopped and liquefied ammonia fuel L is not flowing is not adopted. For this reason, even when the oil burner gun 68 (see FIG. 4) is pulled out as shown in FIG. 3, the combustion air A1 and the outside air A2 are guided along the outer periphery of the inner pipe 60b of the nozzle body 60, thereby making it possible to suppress thermal shock and vapor lock.

[0048] In this embodiment, the nozzle main body 60 that injects the liquefied ammonia fuel L is installed in the oil nozzle compartment 61, but the following modifications are possible.

[0049] 5, the burner 21 may be provided in an air nozzle compartment 74 that includes an air nozzle 73 that supplies air into the furnace 11. The nozzle body 60 is located inside the air nozzle 73.

[0050] 6, the burner 21 may be provided for an air nozzle compartment 74 equipped with two stages of air nozzles 73. The nozzle body 60 is provided in two stages, and is provided corresponding to each of the air nozzles 73.

[0051] In this embodiment, liquefied ammonia fuel is used, but any liquefied gas fuel having a boiling point lower than the ambient temperature of use may be used. For example, the present invention can be applied to a burner that injects dimethyl ether (DME) in liquid form.

[0052] The burners and boilers including the burners described in the above-described embodiments can be understood, for example, as follows.

[0053] A burner (21) according to a first aspect of the present disclosure includes a nozzle body (60) that injects liquefied gas fuel (L) toward a furnace (11), and cooling fluid supply means (60c, 64c) that guides a cooling fluid (A2) having a lower temperature than the fluid flowing outside the nozzle body (60) along the outer peripheral surface of the nozzle body (60).

[0054] In order to cool the outer peripheral surface of the nozzle body that sprays liquefied gas fuel, a cooling fluid having a lower temperature than the fluid flowing on the outside is guided along the outer peripheral surface of the nozzle body by a cooling fluid supply means. Because the cooling fluid has a lower temperature than the fluid flowing on the outside, the temperature difference between the cooling fluid and the liquefied gas fuel flowing inside the nozzle body can be reduced, and thermal shock and vapor lock in the nozzle body can be suppressed. This improves durability and enables stable fuel injection. Liquefied gas fuels are fuels whose boiling points are lower than the ambient temperature of use, and examples thereof include liquefied ammonia and DME.

[0055] In the burner (21) according to a second aspect of the present disclosure, in the first aspect, the cooling fluid (A2) has a lower temperature than the combustion air (A1).

[0056] Combustion air is required to be at least 300°C, which is a large temperature difference from the liquefied gas fuel, and there is a risk of thermal shock or vapor lock occurring. Therefore, it was decided to use a cooling fluid with a lower temperature than the combustion air. The cooling fluid can typically be outside air.

[0057] In a burner (21) according to a third aspect of the present disclosure, in the first or second aspect, the nozzle body (60) includes an inner pipe (60b) and an outer pipe (60c) provided so as to surround the inner pipe (60b), and the cooling fluid (A2) is guided between the inner pipe (60b) and the outer pipe (60c).

[0058] The nozzle body has a double-pipe structure consisting of an inner pipe and an outer pipe, and the cooling fluid is guided between the inner pipe and the outer pipe, which allows the cooling fluid to flow stably along the outer periphery of the inner pipe.

[0059] In the burner (21) according to the fourth aspect of the present disclosure, the flow velocity of the cooling fluid is set to 1 m / s or more.

[0060] By increasing the flow rate of the cooling fluid, it is possible to cool with a small amount of cooling fluid, which reduces the temperature of the fluid (combustion air) flowing outside the nozzle body and prevents a decrease in thermal efficiency.

[0061] A burner (21) according to a fifth aspect of the present disclosure is the burner (21) according to any one of the first to fourth aspects, wherein the nozzle body (60) is branched into a plurality of parts from a main pipe (64) that guides liquefied gas fuel (L) and arranged in parallel.

[0062] Because the nozzle bodies are branched from the main pipe and arranged in parallel, the diameter of each branched nozzle body is small. This reduces the thermal capacity of each nozzle body, resulting in larger temperature changes, making the liquefied gas fuel flowing through the nozzle body more likely to evaporate. Even with this configuration, the cooling fluid is guided along the outer periphery of each nozzle body, thereby suppressing thermal shock and vapor lock.

[0063] A burner (21) according to a sixth aspect of the present disclosure is the burner (21) according to any one of the first to fifth aspects, wherein the nozzle body (60) is arranged facing the furnace (11) even when the burner is stopped and no liquefied gas fuel (L) is flowing from the nozzle body (60).

[0064] The nozzle body is configured to face the furnace even when liquefied gas fuel is not flowing from the nozzle body. In other words, the burner gun method of retracting the nozzle body when liquefied gas fuel is not flowing is not adopted. The cooling fluid is guided along the outer periphery of the nozzle body, which makes it possible to suppress thermal shock and vapor lock.

[0065] A boiler (10) according to a first aspect of the present disclosure includes any one of the burners (21) described above. [Explanation of symbols]

[0066] 10. Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion equipment 21 Burner 22 Fine fuel supply pipe 23 Wind Box 24 Wind road 25 Additional air port 26 Additional air duct 31 mil 32 Forced draft fan 41 Gas duct 42 Air preheater 43 Denitration equipment 44 Dust collection device 46 Desulfurization equipment 47 Chimney 50 Liquid Ammonia Source 60 Nozzle body 60a tip 60b inner tube 60c outer pipe (cooling fluid supply means) 61 Oil nozzle compartment 62 Wind box 62a side wall 64 Master 64b inner tube 64c Outer pipe (cooling fluid supply means) 66 Combustion air nozzle 68 Oil Burner Gun 70 Oil Air Nozzle 73 Air nozzle 74 Air Nozzle Compartment A1 Combustion air A2 Outside air (cooling fluid) L Liquefied ammonia fuel

Claims

1. a nozzle body that injects liquefied gas fuel toward the furnace; a cooling fluid supply means for guiding a cooling fluid having a lower temperature than the fluid flowing outside the nozzle body along the outer circumferential surface of the nozzle body; A burner equipped with:

2. 2. A burner according to claim 1, wherein the cooling fluid is at a lower temperature than the combustion air.

3. the nozzle body includes an inner tube and an outer tube provided to surround the inner tube, 2. The burner of claim 1, wherein the cooling fluid is conducted between the inner tube and the outer tube.

4. 4. The burner according to claim 3, wherein the flow velocity of the cooling fluid is 1 m / s or more.

5. 2. The burner according to claim 1, wherein the nozzle body is branched into a plurality of nozzles arranged in parallel from a main pipe for guiding liquefied gas fuel.

6. 2. The burner according to claim 1, wherein the nozzle body is positioned facing the furnace even when the burner is stopped and no liquefied gas fuel is flowing from the nozzle body.

7. A boiler equipped with the burner according to any one of claims 1 to 6.

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