Gas burners and combustion equipment

Abstract

A gas burner capable of sufficiently suppressing the generation of NOx is provided. [Solution] A gas burner installed in a burner throat that opens into the furnace wall includes a nozzle through which gas fuel containing hydrogen flows, and a combustion air flow path including a combustion air flow path through which combustion air flows to be supplied into the furnace through the burner throat and mixed with the gas fuel ejected from the nozzle. The combustion air flow path has a cylindrical shape and extends along the axis of the nozzle so as to surround the outer periphery of the nozzle. One end of the combustion air flow path on the furnace side is connected to the burner throat. Furthermore, if the air ratio of the combustion air to the gas fuel ejected from the nozzle is m1, then m1≦0.7 is satisfied.

Description

[Technical field]

[0001] The present disclosure relates to a gas burner and a combustion installation. [Background technology]

[0002] For example, Patent Document 1 discloses a gas burner that uses hydrogen gas as fuel. Patent Document 1 discloses a technology for suppressing the mixing of hydrogen gas and oxygen gas by swirling the hydrogen gas and oxygen gas so that their flow velocities are approximately the same, in order to suppress the generation of NOx (nitrogen oxides) due to fuel combustion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-045083 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a risk that the technology described in Patent Document 1 cannot sufficiently suppress the generation of NOx. The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a gas burner that can sufficiently suppress the generation of NOx, and a combustion facility equipped with this gas burner. [Means for solving the problem]

[0005] In order to achieve the above object, the gas burner of the present disclosure comprises a nozzle through which a gas fuel containing hydrogen flows, and a primary air flow path portion including a primary air flow path through which primary air flows to be mixed with the gas fuel ejected from the nozzle, and when the air ratio of the primary air to the gas fuel ejected from the nozzle is m1, it satisfies m1≦0.7. Effect of the Invention

[0006] According to the gas burner of the present disclosure, the generation of NOx can be sufficiently suppressed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing a schematic configuration of a combustion facility including a gas burner according to an embodiment; [Diagram 2] 1 is a diagram illustrating a schematic configuration of a gas burner according to an embodiment of the present invention; [Diagram 3] 4 is a graph showing the relationship between the air ratio and the combustion speed of gas fuel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a gas burner according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment shows one aspect of the present disclosure, and does not limit the present disclosure. The embodiment can be arbitrarily modified within the scope of the technical idea of ​​the present disclosure.

[0009] (Combustion equipment configuration) FIG. 1 is a diagram showing a schematic configuration of a combustion facility 100 including a gas burner 1 according to an embodiment. As shown in FIG. 1, the combustion facility 100 includes a furnace 102, a gas burner 1 that ejects gas fuel F into the furnace 102, a gas fuel supply device 104, and an air supply device 106. The combustion facility 100 is, for example, a boiler that generates high-temperature combustion gas G by burning the gas fuel F ejected into the furnace 102, and generates steam by recovering heat from the high-temperature combustion gas G. The heat of the combustion gas G may be recovered by a heat exchanger provided in the furnace 102, or may be recovered by a heat exchanger provided outside the furnace 102.

[0010] 1, the gas burner 1 ejects a mixture Fa, which is a mixture of a gas fuel F and primary air A1, into the furnace 102 to form a flame X and burn the gas fuel F. In another embodiment, the gas burner 1 ejects each of the gas fuel F and the primary air A1 into the furnace 102 so that the mixture Fa is generated in the furnace 102.

[0011] The gas fuel F contains hydrogen. The gas fuel supply device 104 supplies the gas fuel F containing hydrogen to the gas burner 1. Such a gas fuel supply device 104 includes, for example, a hydrogen gas tank in which hydrogen gas is stored, and supplies the hydrogen gas to the gas burner 1 via a pipe connecting the hydrogen gas tank and the gas burner.

[0012] The air supply device 106 includes, for example, a blower (FDF) for sending air, and supplies primary air A1 to the gas burner 1. In the embodiment illustrated in FIG. 1, the air supply device 106 is configured to supply primary air A1 to the gas burner 1 and to supply secondary air A2 into the furnace 102. A supply port (after-air port) for the secondary air A2 is formed on the wall surface of the furnace 102 so as to be located downstream of the flame position where the flame X is formed in the flow direction of the combustion gas G flowing through the furnace 102. In other words, the combustion equipment 100 is configured to be able to combust unburned gas fuel F contained in the combustion gas G by mixing the combustion gas G with the secondary air A2. The flame position changes depending on the components contained in the gas fuel F and the ejection pressure of the mixture Fa ejected into the furnace 102, but can be estimated in advance.

[0013] (Gas burner configuration) The configuration of a gas burner 1 according to an embodiment will be described. Fig. 2 is a diagram that shows a schematic configuration of the gas burner 1 according to an embodiment. In an embodiment, as shown in Fig. 2, the gas burner 1 includes a nozzle 2 and a primary air passage portion 4. In the embodiment shown in Fig. 2, the gas burner 1 is provided in a burner throat portion 108 that opens into the furnace wall of a furnace 102. The burner throat portion 108 is formed of, for example, a refractory material.

[0014] The nozzle 2 has a cylindrical shape and includes a gas fuel flow passage 6 through which the gas fuel F supplied from a gas fuel supply device 104 flows. A tip 2a of the nozzle 2 is located on the furnace 102 side in an axial direction D1 in which an axis C of the nozzle 2 extends, and forms an outlet 10 of the gas fuel flow passage 6.

[0015] The primary air flow passage section 4 includes a primary air flow passage 8 through which the primary air A1 supplied from the air supply device 106 flows. The primary air flow passage section 4 (sleeve) has a cylindrical shape and extends along the axial direction D1 of the nozzle 2. The inner diameter of the primary air flow passage section 4 is larger than the outer diameter of the nozzle 2, and the nozzle 2 is disposed in the primary air flow passage section 4. The primary air flow passage section 4 includes the primary air flow passage 8 between the inner wall surface of the primary air flow passage section 4 and the outer wall surface of the nozzle 2. In other words, the primary air flow passage 8 is formed on the outer periphery of the nozzle 2. The primary air flow passage section 4 has one end 4a on the furnace 102 side in the axial direction D1 of the nozzle 2 connected to the burner throat section 108 so that the outlet 12 of the primary air flow passage 8 faces the opening 110 of the burner throat section 108.

[0016] The gas burner 1 is configured to mix the gas fuel F ejected from the nozzle 2 with the primary air A1. In the embodiment illustrated in FIG. 2, the gas burner 1 includes a mixing space 14 for mixing the gas fuel F and the primary air A1. This mixing space 14 is formed by positioning the tip 2a of the nozzle 2 on the opposite side to the furnace 102 side from one end 4a of the primary air passage portion 4 in the axial direction D1 of the nozzle 2. That is, the outlet 10 of the gas fuel passage 6 opens into the mixing space 14. The gas fuel F flowing out from the outlet 10 of the gas fuel passage 6 is mixed with the primary air A1 in the mixing space 14, and then ejected into the furnace 102 through the opening 110 of the burner throat portion 108.

[0017] In the gas burner 1 according to one embodiment, when the air ratio of the primary air A1 to the gas fuel F ejected from the nozzle 2 is m1, the air ratio satisfies m1≦0.7. The air ratio refers to the ratio of the amount of air required to completely combust the gas fuel F when the amount of air required to completely combust the gas fuel F is 1. In one embodiment, when the air ratio of the secondary air A2 supplied into the furnace 102 is m2, the combustion equipment 100 satisfies 1≦m1+m2≦1.5, for example, m1+m2=1.2. In other words, the combustion equipment 100 is configured to completely combust the gas fuel F.

[0018] (Action and effect) The action and effect of the gas burner 1 according to one embodiment will be described. Generally, the combustion temperature due to the combustion of a fuel (e.g., hydrogen, propane, methane, etc.) is highest when the air ratio to the fuel is approximately 1 (theoretical air amount). If the air ratio is reduced below 1, the amount of combustible fuel decreases, so the combustion temperature decreases and the generation of NOx is suppressed. According to one embodiment, since m1≦0.7 is satisfied, the combustion temperature due to the combustion of the gas fuel F can be reduced and the generation of NOx can be sufficiently suppressed.

[0019] Conventional gas burners that use city gas, LPG, or the like as gas fuel are often designed to have an air ratio of 0.9 or more for the primary air mixed with the gas fuel. In contrast, according to one embodiment, the gas burner 1 satisfies m1≦0.7, so that the size of the primary air flow passage 8 through which the primary air A1 flows can be made smaller than that of conventional gas burners. Therefore, the gas burner 1 can be made more compact.

[0020] By the way, by making the air ratio of the fuel smaller than 1, the generation of NOx can be suppressed, but the combustion speed (ignition and combustibility) of the fuel may deteriorate. FIG. 3 is a graph showing the relationship between the air ratio and the combustion speed of the gas fuel F, where the horizontal axis represents the air ratio and the vertical axis represents the combustion speed. In FIG. 3, L1 represents the combustion speed of the gas fuel F containing hydrogen, L2 represents the combustion speed of the gas fuel containing propane, and L3 represents the combustion speed of the gas fuel containing methane. L4, L5, and L6 each represent the combustion speed of the gas fuel F containing hydrogen and carbon monoxide. L7 represents the combustion speed of the gas fuel containing carbon monoxide. Each of L1 to L7 increases as the air ratio increases from the air ratio at which combustion occurs, and reaches a maximum value at the air ratio corresponding to each component. And each of L1 to L7 decreases as the air ratio further increases from the air ratio at which the maximum combustion speed occurs.

[0021] As shown in FIG. 3, methane (L2) and propane (L3) have a burning speed exceeding 0 when the air ratio is in the range of about 0.6 to 2. In other words, in order for methane and propane to burn, it is necessary to supply primary air with an air ratio of about 0.6 to 2. The burning speed of methane and propane decreases as the air ratio becomes smaller than 1. In other words, the ignition and combustibility of methane and propane deteriorates when the air ratio is made smaller than 1. Furthermore, since methane and propane contain carbon components, there is a risk of carbon monoxide and soot being generated due to the deterioration of combustibility.

[0022] On the other hand, hydrogen (L1) has a burning speed exceeding 0 when the air ratio is in the range of about 0.2 to 2, and has the maximum burning speed when the air ratio is 0.6. The burning speed of hydrogen decreases as the air ratio becomes smaller than 0.6. The burning speed of hydrogen is very high compared to methane and propane, and the burning speed of hydrogen is higher than the burning speed of methane and propane when the air ratio is 1, even when the air ratio is smaller than 1. In other words, hydrogen has excellent ignition and combustibility under low air ratio conditions compared to methane and propane. In addition, hydrogen does not contain carbon components, so it is also excellent in that it does not generate carbon monoxide or soot when burned.

[0023] According to one embodiment, since the gas fuel F contains hydrogen, even if m1≦0.7 (under low air ratio conditions) is satisfied, the ignition and combustibility of the gas fuel F can be ensured to the extent that the gas fuel F can be combusted in the furnace 102.

[0024] In some embodiments, the gas burner 1 satisfies m1≧0.2. As shown in Fig. 3, if the air ratio of hydrogen is less than 0.2, the combustion speed becomes very slow and there is a risk that hydrogen will not burn. Therefore, by satisfying m1≧0.2, the air ratio m1 of the primary air A1 capable of burning hydrogen can be secured, and the combustion of the gas fuel F containing hydrogen can be promoted.

[0025] In some embodiments, the gas burner 1 satisfies 0.55≦m1≦0.65. As shown in Fig. 3, the combustion speed of hydrogen reaches a maximum value when the air ratio is 0.6. Therefore, by satisfying 0.55≦m1≦0.65, it is possible to improve the ignition and combustibility of the gas fuel F containing hydrogen.

[0026] In some embodiments, the gas fuel F further contains carbon monoxide. And, the ratio of hydrogen to the gas fuel F is 5% by volume or more. Here, L4, L5, and L6 shown in FIG. 3 will be described. In L4, the ratio of carbon monoxide to the gas fuel F is 95% by volume, and the ratio of hydrogen is 5% by volume. In L5, the ratio of carbon monoxide to the gas fuel F is 75% by volume, and the ratio of hydrogen is 25% by volume. In L6, the ratio of carbon monoxide to the gas fuel F is 50% by volume, and the ratio of hydrogen is 50% by volume.

[0027] It is known that carbon monoxide has low ignition and combustibility compared to methane and propane (see L2, L3, and L7 in FIG. 3). However, as shown in FIG. 3, even if the gas fuel F contains carbon monoxide, if the ratio of hydrogen to this gas fuel F is 5% by volume or more, the combustion speed can be made higher than that of gas fuels containing methane or propane. Furthermore, the gas fuel F containing carbon monoxide and hydrogen has the maximum combustion speed when the air ratio m1 is smaller than 1. More specifically, the gas fuel F containing carbon monoxide and hydrogen has the maximum combustion speed at a low air ratio compared to the gas fuel F containing hydrogen. In other words, the gas fuel F containing carbon monoxide and hydrogen has ignition and combustibility to such an extent that it can be burned in the furnace 102 even if the air ratio m1 is 0.7 or less. For this reason, the gas burner 1 can be applied to the combustion of carbon monoxide.

[0028] In some embodiments, the main component of the gas fuel F is carbon monoxide. The main component of the gas fuel F is the component having the highest content among all components contained in the gas fuel F. The gas fuel F may contain components other than carbon monoxide and hydrogen, but the content of carbon monoxide is higher than the content of components other than carbon monoxide. With this configuration, the amount of carbon monoxide burned in the gas burner 1 can be increased.

[0029] The contents described in each of the above embodiments can be understood, for example, as follows.

[0030] [1] A gas burner (1) according to the present disclosure comprises a nozzle (2) through which a gas fuel (F) containing hydrogen flows, and a primary air flow path section (4) including a primary air flow path (8) through which primary air (A1) flows to be mixed with the gas fuel ejected from the nozzle, wherein an air ratio of the primary air to the gas fuel ejected from the nozzle is m1, satisfies m1≦0.7.

[0031] Generally, the combustion temperature of a fuel (e.g., hydrogen, propane, methane, etc.) is highest when the air ratio to the fuel is approximately 1 (theoretical air amount). If the air ratio is reduced below 1, the amount of combustible fuel decreases, so the combustion temperature decreases and the generation of NOx is suppressed. According to one embodiment, since m1≦0.7 is satisfied, the combustion temperature of the gas fuel F can be reduced and the generation of NOx can be sufficiently suppressed.

[0032] As shown in Fig. 3, hydrogen (L1) has a higher combustion speed than methane or propane when the air ratio is 1, even when the air ratio is less than 1. Therefore, according to the configuration described in [1] above, since the gas fuel contains hydrogen, it is possible to ensure the ignition and combustibility of the gas fuel to an extent that the gas fuel can be combusted, even if m1 ≦ 0.7 (low air ratio condition) is satisfied.

[0033] Conventional gas burners that use city gas, LPG, or the like as gas fuel are often designed with an air ratio of 0.9 or more for the primary air mixed with the gas fuel. In contrast, according to the configuration described in [1] above, m1≦0.7 is satisfied, so the size of the primary air flow passage through which the primary air flows can be made smaller than in conventional gas burners. This makes it possible to make the gas burner more compact.

[0034] [2] In some embodiments, in the configuration described in [1] above, m1≧0.2 is satisfied.

[0035] As shown in Fig. 3, when the air ratio is less than 0.2, the combustion speed of hydrogen becomes very slow and there is a risk that hydrogen will not burn. According to the configuration described in [2] above, m1 ≧ 0.2 is satisfied, so that the air ratio of the primary air capable of burning hydrogen is ensured and the combustion of gas fuel containing hydrogen can be promoted.

[0036] [3] In some embodiments, in the configuration described in [1] or [2] above, the gas fuel further contains carbon monoxide, and the ratio of the hydrogen to the gas fuel is 5 volume % or more.

[0037] Carbon monoxide is known to have low ignition and combustibility compared to methane and propane (see L2, L3, and L7 in FIG. 3). However, as shown in FIG. 3, a gas fuel containing carbon monoxide and hydrogen has a combustion speed (ignition and combustibility) that allows combustion even if the air ratio m1 is 0.7 or less, as long as the ratio of hydrogen to this gas fuel F is 5% by volume or more. Therefore, according to the configuration described in [3] above, the gas burner 1 can be applied to the combustion of carbon monoxide.

[0038] [4] In some embodiments, in the configuration described in [3] above, the main component of the gas fuel is carbon monoxide.

[0039] According to the configuration described in [4] above, the amount of carbon monoxide burned by the gas burner can be increased.

[0040] [5] A combustion facility (100) according to the present disclosure includes a furnace (102) and a gas burner according to any one of [1] to [4] above that ejects gas fuel into the furnace.

[0041] According to the configuration described in [5] above, the generation of NOx by the gas burner can be suppressed, and therefore the amount of NOx emitted from the combustion equipment can be suppressed. [Explanation of symbols]

[0042] 1 Gas burner 2 Nozzles 4 Primary air passage 8 Primary Air Flow Path 100 Combustion equipment 102 Furnace A1 Primary air F Gas fuel m1 Air ratio

Claims

1. A gas burner provided in a burner throat portion that opens into a furnace wall of a furnace, a nozzle through which a gas fuel containing hydrogen flows; a combustion air flow path portion including a combustion air flow path through which combustion air flows to be supplied into the furnace through the burner throat portion and mixed with the gas fuel ejected from the nozzle, The combustion air flow path portion has a cylindrical shape and extends along an axis of the nozzle so as to surround an outer periphery of the nozzle, One end of the combustion air passage portion on the furnace side is connected to an upstream end of an inner circumferential surface of the burner throat portion that defines an opening of the burner throat portion, The nozzle includes a gas fuel flow passage through which the gas fuel flows, a tip of the nozzle is located on the furnace side in an axial direction along which the axis of the nozzle extends, and forms an outlet of the gas fuel flow path so as to eject the gas fuel in a direction along the axis of the nozzle; The gas burner further includes a mixing space formed in the combustion air passage portion by positioning the tip of the nozzle on the opposite side to the furnace side relative to the one end of the combustion air passage portion in the axial direction of the nozzle, If the air ratio of the combustion air to the gas fuel ejected from the nozzle is m1, m1≦0.7 is satisfied; Gas burner.

2. m1≧0.2 is satisfied; 2. A gas burner according to claim 1.

3. The gas fuel further comprises carbon monoxide; The ratio of the hydrogen to the gas fuel is 5% by volume or more.

3. A gas burner according to claim 1 or 2.

4. The main component of the gas fuel is carbon monoxide.

4. A gas burner according to claim 3.

5. The furnace and The gas burner according to any one of claims 1 to 4, which ejects gas fuel into the furnace. Combustion equipment.

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