Burner and boiler provided with same

Abstract

The present invention provides a burner capable of suppressing thermal shock and vapor lock even when liquefied gas fuel is used. A burner (21) comprises: nozzle bodies (60) for injecting liquefied ammonia fuel (L) toward a furnace (11); and outer pipes (60c, 64c) for guiding, along the outer peripheral surface of the nozzle bodies (60), outside air (A2) having a temperature lower than that of combustion air (A1) flowing outside the nozzle bodies (60). The nozzle bodies (60) each comprise an inner tube (60b) and an outer tube (60c) disposed so as to cover the periphery of the inner tube (60b), and outside air (A2) is guided between the inner tube (60b) and the outer tube (60c).

Description

Burner and boiler equipped with same

[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.

[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. The heat exchanger is installed in the area where the combustion gas flows, and water or steam flowing through heat transfer tubes constituting the heat exchanger is heated to generate superheated steam.

[0003] 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 (see, for example, Patent Document 1).

[0004] Japanese Patent Application Publication No. 10-68510

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

[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 vaporized ammonia expands in volume, 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.

[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.

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

[0014] Fig. 1 is a schematic diagram showing a boiler according to an embodiment of the present disclosure; Fig. 2 is a cross-sectional view showing a burner according to an embodiment of the present disclosure; Fig. 3 is a cross-sectional side view showing the burner of Fig. 2; Fig. 4 is a cross-sectional side view showing an oil burner gun installed in Fig. 3; Fig. 5 is a cross-sectional side view showing a burner installed in an air nozzle compartment; Fig. 6 is a cross-sectional side view showing a burner installed in an air nozzle compartment with two stages of air nozzles;

[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 the liquid ammonia (NH ３ The boiler 10 of this embodiment is a boiler that can burn liquid ammonia fuel, pulverized fuel obtained by pulverizing solid fuel (coal or biomass fuel), or oil fuel such as heavy oil using a burner, and can exchange 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. The heat generated by the combustion of pulverized fuel is recovered by heat exchange with water and steam circulating inside the heat transfer tubes, and the temperature rise of the furnace wall 101 is suppressed.

[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 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 the opposing furnace walls 101, so as to perform opposed combustion), and are arranged in multiple rows along the vertical direction. The shape of the furnace, the number of burner rows, the number of burners per row, the arrangement of the burners, etc. are not limited to this embodiment.

[0019] The 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 the pulverized fuel supply pipes are not distinguished, they will be simply referred to as "pulverized fuel supply pipes 22") via a plurality of pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F, respectively (hereinafter, when the pulverized fuel supply pipes are not distinguished, they will be simply referred to as "mills 31"). The mill 31 is, for example, a vertical roller mill having a rotatable pulverizing table (not shown) supported therein and a plurality of pulverizing rollers (not shown) supported above the pulverizing table so as to be rotatable in conjunction with the rotation of the pulverizing table. The solid fuel pulverized by the cooperation of the pulverizing rollers and the pulverizing table is transported to a classifier (not shown) provided in the mill 31 by primary air (carrier gas, oxidizing gas) supplied to the 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. The other end of the air duct 24 is connected to a forced draft fan (FDF) 32. Air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24 and 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 an 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 downstream 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, thereby 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] 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, that 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 devices such as a dust collector 44, such as an electrostatic precipitator, that removes ash and the like from the combustion gas, a desulfurization device 46 that removes sulfur oxides, and an induced draft fan (IDF) 45 that guides the exhaust gas to these environmental devices. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas treated in the environmental device 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 (the total amount of primary air and secondary air) supplied to the burner 21 is set to be less than the theoretical air amount relative to the amount of fuel supplied to the burner 21. This creates a reducing atmosphere in 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, 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 from which NOx has been reduced, completing 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 combustion 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 combustion gas is then discharged to the outside of the system through a chimney 47. 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 includes 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 a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium, for example, 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) the 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 extending horizontally so as to penetrate from the outside into a side wall 62a of the wind box 62. The oil burner gun 68 is used when burning a fuel other than the liquefied ammonia fuel L, but by switching the fuel supply line, it may also be used when burning the liquefied ammonia fuel L with the oil burner gun 68.

[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 eight nozzle bodies 60 are shown in FIG. 2, the number is not limited to eight and 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 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 the 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 surrounding the inner pipe 60b. The inner pipe 60b of each nozzle body 60 communicates with the inner pipe 64b of the main pipe 64, through which liquefied ammonia fuel L is introduced. The outer pipe 60c of each nozzle body 60 communicates with the outer pipe 64c of the main pipe 64, through which outside air A2 is introduced. The outer pipe 60c extends to the tip of the inner pipe 60b, so that the 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 burning liquefied ammonia fuel L 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] During extinguishing, the oil burner gun 68 can be pulled out from the position shown in FIG. 4 to the outside of the furnace, thereby avoiding damage due to radiant heat from the furnace 11. Meanwhile, the nozzle body 60 is fixed in position and faces the furnace 11 regardless of the operating state (ignition state or extinguishing state). That is, the nozzle body 60 faces the furnace 11 during both ignition and extinguishing states. During ignition, when liquefied ammonia fuel L is flowing through the inner tube 60b of the nozzle body 60, the inner tube 60b is cooled by the liquefied ammonia fuel L, so there is no risk of damage due to radiant heat. However, when the liquefied ammonia fuel L is not flowing through the inner tube 60b of the nozzle body 60 and is stopped (during extinguishing), there is a risk of thermal damage because cooling by the liquefied ammonia fuel L is not performed. Therefore, even during extinguishing, the nozzle body 60 continues to flow outside air A2 from the outer tube 60c. This prevents 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, thermal shock and vapor lock can be suppressed.

[0044] The effects of the present embodiment described above are as follows. 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 guided 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, and thermal shock and vapor lock in the nozzle body 60 can be suppressed. 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 branched nozzle body 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 furnace 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 furnace 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 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 having two stages of air nozzles 73. The nozzle body 60 is provided in two stages, and each stage corresponds to one of the air nozzles 73.

[0051] Although liquefied ammonia fuel is used in this embodiment, 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 temperature lower than that of a 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, thereby suppressing thermal shock and vapor lock in the nozzle body. This improves durability and enables stable fuel spray. The liquefied gas fuel is a fuel with a boiling point lower than the ambient temperature, such as liquefied ammonia or 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 temperature lower than that of the combustion air (A1).

[0056] The 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, a cooling fluid with a lower temperature than the combustion air is used. Typically, outside air can be used as the cooling fluid.

[0057] In the 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 any one of the first to fourth aspects, in which the nozzle body (60) is branched into multiple 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] In the burner (21) according to the sixth aspect of the present disclosure, in any of the first to fifth aspects, 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.

[0066] REFERENCE SIGNS LIST 10 Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion device 21 Burner 22 Pulverized fuel supply pipe 23 Wind box 24 Wind duct 25 Additional air port 26 Additional air duct 31 Mill 32 Forced draft fan 41 Gas duct 42 Air preheater 43 Denitrification device 44 Dust collector 46 Desulfurization device 47 Chimney 50 Liquid ammonia supply source 60 Nozzle body 60a Tip 60b Inner tube 60c Outer tube (cooling fluid supply means) 61 Oil nozzle compartment 62 Wind box 62a Side wall 64 Main tube 64b Inner tube 64c Outer tube (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 burner comprising: a nozzle body that injects liquefied gas fuel toward a furnace; and a cooling fluid supply means that guides a cooling fluid, the temperature of which is lower than that of the fluid flowing outside the nozzle body, along the outer circumferential surface of the nozzle body.

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

3. A burner as claimed in claim 1, wherein the nozzle body comprises an inner tube and an outer tube provided so as to surround the inner tube, and the cooling fluid is guided between the inner tube and the outer tube.

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

5. A 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. A 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 a burner according to any one of claims 1 to 6.

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