Gas burners and combustion equipment

Abstract

To attain a suitable combustion state when using gas fuel including hydrogen.SOLUTION: A gas burner for burning gas fuel including hydrogen includes: a nozzle in which a main jet part for jetting gas fuel, the main jet part including at least one main hole and an auxiliary jet part for jetting smaller amount of gas fuel than that the main jet part jets, the auxiliary jet part including at least one auxiliary hole are formed at a tip part; a primary air flow passage part surrounding the periphery of the tip part of the nozzle in front view visually recognized in the axial line direction of the nozzle and forming a primary air outlet from which primary air flows out; and a secondary air flow passage part located on the upper side or lower side of the primary air outlet in front view and forming a secondary air outlet from which secondary air flows out. In front view, a jet direction of the at least one auxiliary hole is oriented in a direction intersecting with the secondary air outlet, and a jet direction of the at least one main hole is oriented in a direction that does not intersect with the secondary air outlet.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a gas burner for burning a gas fuel containing hydrogen and combustion equipment.

Background Art

[0002] In combustion equipment such as a boiler, a burner for burning fuel is installed, and techniques for enhancing flame retention and suppressing the generation of nitrogen oxides (NOx) to achieve a suitable combustion state are known. For example, Patent Document 1 discloses a gas burner including a flame stabilizer having a split shape that is arranged on the central axis of a nozzle and widens toward the downstream side in the flow direction of fuel gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in some combustion equipment, efforts are being made to switch from fossil fuels (decarbonization) for the purpose of reducing the emissions of carbon dioxide, which is a typical greenhouse gas. As one form of this decarbonization, a gas fuel containing hydrogen may be applied as the fuel of a gas burner. Hydrogen has characteristics significantly different from those of components contained in conventional fuels (for example, methane contained in city gas, propane contained in LPG, and fine coal contained in the fuel gas described in Patent Document 1). However, the technology described in Patent Document 1 does not have a configuration for enhancing flame retention or suppressing the generation of NOx in consideration of the characteristics of hydrogen. That is, when a gas burner uses a gas fuel containing hydrogen, there is room for improving the gas burner to a configuration in which the characteristics of hydrogen are considered.

[0005] This disclosure has been made in view of the above-mentioned problems and aims to provide a gas burner that can achieve a suitable combustion state when using a gaseous fuel containing hydrogen. [Means for solving the problem]

[0006] To achieve the above objective, the gas burner according to the present disclosure is a gas burner for burning a gas fuel containing hydrogen, comprising: a nozzle having a main ejection part for ejecting the gas fuel and including at least one main hole, and a secondary ejection part for ejecting a smaller amount of the gas fuel than the main ejection part and including at least one secondary hole, formed at its tip; a primary air passage section that surrounds the tip of the nozzle and forms a primary air outlet from which primary air flows out, as viewed from the front along the axial direction of the nozzle; and a secondary air passage section that is located above or below the primary air outlet and forms a secondary air outlet from which secondary air flows out, as viewed from the front, wherein, as viewed from the front, the ejection direction of the at least one secondary hole is oriented in a direction intersecting the secondary air outlet, and the ejection direction of the at least one main hole is oriented in a direction not intersecting the secondary air outlet. [Effects of the Invention]

[0007] The gas burner of this disclosure can achieve a suitable combustion state when using a gaseous fuel containing hydrogen. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows the configuration of the combustion equipment according to the first embodiment. [Figure 2] This diagram schematically shows the internal configuration of a furnace according to the first embodiment. [Figure 3] This diagram schematically shows the configuration of a gas burner according to the first embodiment. [Figure 4] This diagram schematically shows the internal configuration of a gas burner according to the first embodiment. [Figure 5]This is a diagram illustrating the ejection direction of the main hole according to the first embodiment. [Figure 6] This is a diagram illustrating the ejection direction of the secondary hole according to the first embodiment. [Figure 7] This is a diagram illustrating the flame-holding surface of a flame holder according to the first embodiment. [Figure 8] This figure shows the configuration of the nozzle tip according to several embodiments. [Figure 9] This figure shows the configuration of the nozzle tip according to the second embodiment. [Figure 10] This figure shows the shape of the main hole according to a modified example of the second embodiment. [Figure 11] This diagram schematically shows the configuration of a gas burner according to the third embodiment. [Figure 12] This is a diagram illustrating the layout of the secondary air outlet according to the third embodiment. [Figure 13A] This diagram schematically shows the internal configuration of a furnace according to several embodiments. [Figure 13B] This diagram schematically shows the internal configuration of a furnace according to several embodiments. [Figure 13C] This diagram schematically shows the internal configuration of a furnace according to several embodiments. [Modes for carrying out the invention]

[0009] Hereinafter, a gas burner according to an embodiment of the present disclosure will be described with reference to the drawings. Such embodiments represent one aspect of the present disclosure and are not limiting, and can be modified at will within the scope of the technical idea of ​​the present disclosure.

[0010] <First Embodiment> (composition) FIG. 1 is a diagram schematically showing the configuration of a combustion facility 1 according to the first embodiment. As illustrated in FIG. 1, the combustion facility 1 includes a furnace 2 and a gas burner 4 provided in the furnace 2 for burning a gas fuel F containing hydrogen in the furnace 2. The combustion facility 1 is, for example, a boiler, which generates high-temperature exhaust gas G by generating and burning a flame X with the gas fuel F ejected into the furnace 2 from the gas burner 4, and generates steam by recovering heat from the high-temperature exhaust gas G. The heat of the exhaust gas G may be recovered by a heat exchanger provided in the furnace 2 or by a heat exchanger provided outside the furnace 2.

[0011] In the present disclosure, the "gas fuel F containing hydrogen" includes those containing hydrogen and fuels other than hydrogen (mixed combustion) and those containing only hydrogen (pure combustion). Further, even those containing hydrogen and fuels other than hydrogen can be classified into those with hydrogen as the main fuel (the volume ratio of hydrogen is 50% or more) and those with fuels other than hydrogen as the main fuel (the volume ratio of hydrogen is less than 50%). The "gas fuel containing hydrogen" includes all these cases.

[0012] The configuration of the furnace 2 will be described. FIG. 2 is a diagram schematically showing the internal configuration of the furnace 2 according to the first embodiment, which is a view of the furnace 2 viewed from the vertical direction. In the first embodiment, the furnace 2 has a rectangular prism shape with a longitudinal direction along the vertical direction. And, as illustrated in FIG. 2, a combustion space 6 for burning the gas fuel F ejected from the gas burner 4 is formed in the furnace 2. The combustion space 6 of this furnace 2 has a rectangular shape.

[0013] The furnace 2 includes a first furnace wall 8 including a first inner peripheral surface 7a corresponding to any one of the rectangular sides of the combustion space 6 on the inner peripheral surface 7 of the furnace 2, a second furnace wall 10 located on the opposite side of the first furnace wall 8 across the combustion space 6, a third furnace wall 12 connecting one end 16 of the first furnace wall 8 and one end 18 of the second furnace wall 10, and a fourth furnace wall 14 connecting the other end 17 of the first furnace wall 8 and the other end 19 of the second furnace wall 10. The third furnace wall 12 is located on the opposite side of the fourth furnace wall 14 across the combustion space 6. The combustion space 6 of the furnace 2 is formed in a rectangular shape by being surrounded by the first furnace wall 8, the second furnace wall 10, the third furnace wall 12, and the fourth furnace wall 14.

[0014] In the first embodiment, as illustrated in FIG. 2, the furnace 2 is provided with a plurality of gas burners 4. The plurality of gas burners 4 includes a first gas burner 4A(4) provided on the first furnace wall 8 so as to be closer to the fourth furnace wall 14 than the third furnace wall 12, a second gas burner 4B(4) provided on the second furnace wall 10 so as to be closer to the third furnace wall 12 than the fourth furnace wall 14, a third gas burner 4C(4) provided on the third furnace wall 12 so as to be closer to the first furnace wall 8 than the second furnace wall 10, and a fourth gas burner 4D(4) provided on the fourth furnace wall 14 so as to be closer to the second furnace wall 10 than the first furnace wall 8. Each of the plurality of gas burners 4 ejects gas fuel F at the rectangular corner 21 of the combustion space 6. Although not shown, the plurality of gas burners 4 may further include an upper gas burner stacked on the first gas burner 4A.

[0015] The gas burner 4 burns the gas fuel F. In the first embodiment, as illustrated in FIG. 1, the combustion equipment 1 further includes a gas fuel supply device 100 that supplies the gas fuel F to the gas burner 4 and an air supply device 102 that supplies combustion air A to the gas burner 4. Then, the gas burner 4 mixes the gas fuel F supplied from the gas fuel supply device 100 with the combustion air A supplied from the air supply device 102 and ejects it into the furnace 2 (combustion space 6) to burn the gas fuel F.

[0016] The gas fuel supply device 100 includes a gas tank 104 in which gas fuel F is stored, and a fuel supply line 106 that connects the gas tank 104 to the gas burner 4 and allows the gas fuel F stored in the gas tank 104 to flow toward the gas burner 4.

[0017] The air supply device 102 includes an air supply line 108, one end of which is open to the atmosphere and the other end of which is connected to the gas burner 4, and a blower 110 provided on the air supply line 108, which blows the air taken in from one end of the air supply line 108 as combustion air A to the furnace 2.

[0018] The configuration of the gas burner 4 will now be explained in detail. Figure 3 is a schematic diagram showing the configuration of the gas burner 4 according to the first embodiment, and is a front view of the gas burner 4 as seen from the combustion space 6 side of the furnace 2. Figure 4 is a schematic diagram showing the internal configuration of the gas burner 4 according to the first embodiment, and is a view of the gas burner 4 as seen along the left-right direction D3, which will be described later.

[0019] Hereinafter, the direction in which the axis O of the nozzle 20 of the gas burner 4 extends will be referred to as the axial direction D1 of the nozzle 20. When the gas burner 4 is viewed from the combustion space 6 side of the furnace 2, the direction perpendicular to the vertical direction D2 will be referred to as the left-right direction D3.

[0020] As illustrated in Figures 3 and 4, the gas burner 4 comprises a nozzle 20, a primary air passage section 22, a secondary air passage section 24, and a flame holder 50. In the first embodiment, as illustrated in Figure 3, the gas burner 4 is a rectangular burner in which the front surface 5 facing the combustion space 6 of the furnace 2 has a longitudinal direction along the vertical direction D2.

[0021] The nozzle 20 has a cylindrical shape, for example, centered on axis O, so that the gas fuel F can flow through it. As illustrated in Figure 4, the nozzle 20 injects the gas fuel F supplied from the gas fuel supply device 100 into the combustion space 6 of the furnace 2. Specifically, as illustrated in Figure 3, the tip 26 (burner tip) of the nozzle 20 has a main injection section 28 and a sub-injection section 30. The main injection section 28 injects a portion of the gas fuel F supplied from the gas fuel supply device 100 into the combustion space 6 of the furnace 2, and the sub-injection section 30 injects the remaining portion of the gas fuel F supplied from the gas fuel supply device 100 into the combustion space 6 of the furnace 2. The sub-injection section 30 is configured to inject a smaller amount of gas fuel F than the main injection section 28. In other words, the amount of a portion of the gas fuel F ejected from the main injection section 28 is greater than the amount of the remaining gas fuel F ejected from the sub-injection section 30.

[0022] In the first embodiment, as illustrated in Figure 3, the main ejection section 28 includes two main holes 32. The first main hole 32A(32) is located on the opposite side of the axis O of the nozzle 20 in the left-right direction D3 from the second main hole 32B(32). The first main hole 32A is located to the left of the axis O of the nozzle 20, and the second main hole 32B is located to the right of the axis O of the nozzle 20.

[0023] In the first embodiment, as illustrated in Figure 3, the secondary ejection section 30 includes two secondary holes 34. The first secondary hole 34A(34) is located on the opposite side of the axis O of the nozzle 20 in the vertical direction D2 from the second secondary hole 34B(34). The first secondary hole 34A is located above the axis O of the nozzle 20, and the second secondary hole 34B is located below the axis O of the nozzle 20.

[0024] The first main hole 32A and the second main hole 32B are located between the first sub-hole 34A and the second sub-hole 34B in the vertical direction D2. The first sub-hole 34A and the second sub-hole 34B are located between the first main hole 32A and the second main hole 32B in the left-right direction D3.

[0025] The first main hole 32A has a larger diameter than the first sub-hole 34A and the second sub-hole 34B, respectively. The second main hole 32B has a larger diameter than the first sub-hole 34A and the second sub-hole 34B, respectively. The first main hole 32A and the second main hole 32B have the same diameter. The first sub-hole 34A and the second sub-hole 34B have the same diameter. In this way, the total opening area of ​​the main holes 32 is greater than the total opening area of ​​the sub-holes 34, and the main ejection section 28 is able to eject more gaseous fuel F than the sub-ejection section 30.

[0026] As illustrated in Figure 3, the primary air passage section 22 surrounds the tip 26 of the nozzle 20 in a front view (hereinafter referred to as "front view") along the axial direction D1 of the nozzle 20. This primary air passage section 22 forms a primary air outlet 36 through which the combustion air A supplied from the air supply device 102 flows out as primary air A1.

[0027] In the first embodiment, as illustrated in Figure 4, the primary air passage section 22 includes a primary air passage 38 through which primary air A1 supplied from the air supply device 102 flows. The primary air passage section 22 (sleeve) has a cylindrical shape and extends along the axial direction D1 of the nozzle 20. The inner diameter of the primary air passage section 22 is larger than the outer diameter of the nozzle 20, and the nozzle 20 is positioned inside the primary air passage section 22. In other words, the primary air passage section 22 includes a primary air passage 38 through which primary air A1 flows between the inner wall surface of the primary air passage section 22 and the outer wall surface of the nozzle 20. To put it another way, the primary air passage 38 is formed on the outer circumference of the nozzle 20.

[0028] As illustrated in Figure 3, the secondary air passage section 24 is located above or below the primary air outlet 36 in a front view and forms a secondary air outlet 40 from which secondary air A2, which comes into contact with the gas fuel F later than the primary air A1, flows out. The secondary air A2 may be combustion air A supplied from the air supply device 102, or it may be circulating gas Eg obtained by circulating a portion of the exhaust gas G discharged from the furnace 2 back into the furnace 2. Alternatively, the secondary air A2 may be a mixture of combustion air A and circulating gas Eg.

[0029] In the first embodiment, the secondary air passage section 24 includes an upper secondary air passage section 24A(24) and a lower secondary air passage section 24B(24). The secondary air outlet 40A(40) of the upper secondary air passage section 24A is located above the primary air outlet 36. In the left-right direction D3, the primary air outlet 36 and the secondary air outlet 40A of the upper secondary air passage section 24A overlap at least partially. The secondary air outlet 40B(40) of the lower secondary air passage section 24B is located below the primary air outlet 36. In the left-right direction D3, the primary air outlet 36 and the secondary air outlet 40B of the lower secondary air passage section 24B overlap at least partially. The secondary air outlet 40A of the upper secondary air passage section 24A is located on the opposite side of the primary air outlet 36 from the secondary air outlet 40B of the lower secondary air passage section 24B.

[0030] In the first embodiment, the secondary air outlet 40 includes an inner outlet 42 and an outer outlet 44 located further away from the primary air outlet 36 than the inner outlet 42. That is, the secondary air outlet 40A of the upper secondary air passage section 24A includes an inner outlet 42A(42) and an outer outlet 44A(44). The secondary air outlet 40B of the lower secondary air passage section 24B includes an inner outlet 42B(42) and an outer outlet 44B(44). In a front view, from top to bottom, the outer outlet 44A of the secondary air outlet 40A, the inner outlet 42A of the secondary air outlet 40A, the primary air outlet 36, the inner outlet 42B of the secondary air outlet 40B, and the outer outlet 44B of the secondary air outlet 40B are arranged in that order.

[0031] The outer outlet 44 is configured to discharge secondary air A2. In the first embodiment, as illustrated in Figure 4, the outer outlet 44 discharges combustion air A supplied from the air supply device 102 as secondary air A2. In the first embodiment, the outer outlet 44 has a rectangular shape in a front view, but the disclosure is not limited to this form.

[0032] The inner outlet 42 is configured to discharge low-oxygen secondary air A3, which has a lower oxygen concentration than the secondary air A2 discharged from the outer outlet 44. In the first embodiment, as illustrated in Figure 4, the low-oxygen secondary air A3 is circulating gas Eg, which is a portion of the exhaust gas G discharged from the furnace 2 that is recirculated back into the furnace 2. In the first embodiment, the inner outlet 42 has a rectangular shape in a front view, but the disclosure is not limited to this form.

[0033] As illustrated in Figure 3, in a front view, the ejection direction D4 of the main hole 32 is oriented so as not to intersect with the secondary air outlet 40. Furthermore, in a front view, the ejection direction D5 of the sub-hole 34 is oriented so as to intersect with the secondary air outlet 40. In the first embodiment, the ejection direction D4 of the first main hole 32A is to the left, and the ejection direction D4 of the second main hole 32B is to the right. The ejection direction D5 of the first sub-hole 34A is upward, and the ejection direction D5 of the second sub-hole 34B is downward.

[0034] Figure 5 is a diagram illustrating the ejection direction D4 of the main hole 32 according to the first embodiment, and shows the tip portion 26 of the nozzle 20 viewed along the vertical direction D2. Figure 6 is a diagram illustrating the ejection direction D5 of the sub-hole 34 according to the first embodiment, and shows the tip portion 26 of the nozzle 20 viewed along the left-right direction D3.

[0035] As illustrated in Figure 5, in the first embodiment, the tip portion 26 of the nozzle 20 includes a flat first end face 37 facing to the left or to the right. The first end face 37 connects the tip surface 41 and side surface 43 on the outermost side (combustion space 6 side) of the tip portion 26 of the nozzle 20 in the axial direction D1. The main hole 32 is formed in this first end face 37, and the ejection direction D4 of the main hole 32 is perpendicular to this first end face 37. The angle formed by the ejection direction D4 of the main hole 32 and the axial direction D1 of the nozzle 20 is defined as θ1.

[0036] As illustrated in Figure 6, in the first embodiment, the tip portion 26 of the nozzle 20 includes a flat second end face 39 facing upward or downward. The second end face 39 connects the tip surface 41 and the side surface 43 of the tip portion 26 of the nozzle 20. A sub-hole 34 is formed in this second end face 39, and the ejection direction D5 of the sub-hole 34 is perpendicular to this second end face 39. The angle formed by the ejection direction D5 of the sub-hole 34 and the axial direction D1 of the nozzle 20 is denoted as θ2. In the first embodiment, θ1 < θ2 is satisfied.

[0037] The flame holder 50, as illustrated in Figure 4, is provided at the tip 26 of the nozzle 20 and has a flame-holding surface 52 that moves away from the axis O of the nozzle 20 as it approaches the primary air outlet 36. In the first embodiment, the flame holder 50 includes a plurality of blades 54 extending radially outward from the tip 26 of the nozzle 20, centered on the axis O of the nozzle 20. The plurality of blades 54 are arranged in a line along the circumferential direction centered on the axis O of the nozzle 20. For example, 15 blades 54 are arranged at 24-degree intervals along the circumferential direction.

[0038] In the first embodiment, the flame holder 50 was a fin-type flame holder (so-called a swirler) including a plurality of wings 54, but the disclosure is not limited to this form. In some embodiments, the flame holder 50 is a dish-type flame holder (so-called a diffuser) including a plate portion surrounding the tip portion 26 of the nozzle 20. The plate portion has a hole into which the tip portion 26 of the nozzle 20 is fitted. When the flame holder 50 includes a plate portion, the flame-holding surface 52 of the flame holder 50 is the surface of the plate portion on one side (combustion space 6 side) in the axial direction D1 of the nozzle 20.

[0039] Figure 7 is a diagram illustrating the flame-holding surface 52 of the flame holder 50 according to the first embodiment. In the first embodiment, the flame-holding surface 52 is the trailing edge 53 of the wing 54 facing one side (the combustion space 6 side) in the axial direction D1 of the nozzle 20. If the angle formed by the trailing edge 53 of the wing 54 and the axial direction D1 of the nozzle 20 is θ3, then θ2 ≤ θ3 is satisfied. In some embodiments, if the contact point where the trailing edge 53 of the wing 54 and the tip 26 of the nozzle 20 come into contact is P, then the angle θ31 formed by the tangent 59 passing through the contact point P and the axis O of the nozzle 20 satisfies θ2 ≤ θ31.

[0040] (Effects / Actions) The operation and effects of the gas burner 4 according to the first embodiment will now be explained. Hydrogen has a higher combustion rate compared to the components contained in conventional gas fuels. Therefore, when hydrogen is included in the gas fuel F, the amount of gas fuel F used to maintain the flame of the gas burner 4 can be reduced. On the other hand, because the mixing of hydrogen and oxygen occurs rapidly, the temperature of the combustion space 6 in which the gas fuel F is burned is rapidly increased, promoting the generation of nitrogen oxides (NOx).

[0041] In contrast, according to the first embodiment, as illustrated in Figure 3, in a front view, the ejection direction D5 of the sub-hole 34 is oriented in a direction intersecting the secondary air outlet 40. Therefore, the small amount of gaseous fuel F ejected from the sub-hole 34 can be quickly brought into contact with the secondary air A2 or low-oxygen secondary air A3 flowing out from the secondary air outlet 40, thereby improving flame retention. In other words, flame retention can be ensured with a small amount of gaseous fuel F.

[0042] Furthermore, as illustrated in Figure 3, in a front view, the ejection direction D4 of the main hole 32 is oriented so as not to intersect with the secondary air outlet 40. Therefore, the large amount of gaseous fuel F ejected from the main hole 32 comes into contact with the secondary air A2 and low-oxygen secondary air A3 flowing out from the secondary air outlet 40 at a later stage than the gaseous fuel F ejected from the sub-hole 34. In other words, the gaseous fuel F ejected from the main hole 32 flows into a region with a relatively low oxygen concentration, spaced apart on one side of the axial direction D1 (towards the depth of the combustion space 6) from the tip 26 of the nozzle 20. This slows down the mixing of hydrogen and oxygen and promotes slow combustion, thereby suppressing the temperature rise of the combustion space 6 and reducing the generation of NOx. Thus, a suitable combustion state (ensuring flame retention and suppressing NOx generation) can be achieved when using gaseous fuel containing hydrogen.

[0043] According to the first embodiment, low-oxygen secondary air A3 flows out from the inner outlet 42, and secondary air A2 flows out from the outer outlet 44. Therefore, the low-oxygen secondary air A3 flowing out from the inner outlet 42 comes into contact with the gaseous fuel F ejected from the main hole 32 before the secondary air A2 flowing out from the outer outlet 44. This further slows down the mixing of hydrogen and oxygen, and further suppresses the temperature rise in the combustion space 6.

[0044] According to the first embodiment, the ejection direction D4 of the first main hole 32A is to the left, and the ejection direction D4 of the second main hole 32B is to the right. Therefore, the nozzle 20 (main ejection section 28) can widely eject gaseous fuel F into the combustion space 6 in the left-right direction D3.

[0045] According to the first embodiment, the ejection direction D5 of the first sub-hole 34A is upward, and the ejection direction D5 of the second sub-hole 34B is downward. Therefore, the nozzle 20 (sub-injection section 30) can widely eject the gaseous fuel F in the vertical direction D2 into the combustion space 6.

[0046] According to the first embodiment, since θ1 < θ2 is satisfied, the contact between the small amount of gaseous fuel F ejected from the sub-hole 34 and the secondary air A2 or low-oxygen secondary air A3 flowing out from the secondary air outlet 40 can be accelerated, while the contact between the large amount of gaseous fuel F ejected from the main hole 32 and the secondary air A2 or low-oxygen secondary air A3 flowing out from the secondary air outlet 40 can be delayed.

[0047] In some embodiments, the conditions θ1 < θ2 and 15 degrees < θ1 < 45 degrees are satisfied. If θ1 exceeds 45 degrees, the momentum of the gas fuel F ejected to one side in the axial direction D1 decreases, and the supply of gas fuel F to the depth side of the combustion space 6 may become insufficient. In this case, local fluctuations in the heat generation rate occur within the combustion space 6, making combustion oscillations more likely to occur. In other words, the potential for combustion oscillations due to pressure fluctuations in the combustion space 6 increases. Also, if θ1 is less than 15 degrees, the flame lengthening becomes excessive, affecting the heat absorption characteristics. For this reason, by satisfying 15 degrees < θ1 < 45 degrees, combustion oscillations can be suppressed, and the temperature rise of the combustion space 6 can be suppressed by slow combustion due to moderate flame lengthening.

[0048] In some embodiments, the conditions θ1 < θ2 and 35 degrees < θ2 < 55 degrees are satisfied. If θ2 exceeds 55 degrees, the flame-holding effect near the flame holder 50 becomes too strong, which increases the burnout potential of the flame holder 50 and may promote the generation of NOx. Also, if θ2 is less than 35 degrees, the flame-holding effect of the flame holder 50 weakens, and the vibration potential increases. By satisfying 35 degrees < θ2 < 55 degrees, combustion vibration, damage to the flame holder 50, and NOx generation can be suppressed in a balanced manner.

[0049] According to the first embodiment, since θ2 ≤ θ3 is satisfied, damage to the flame holder 50 caused by the flame X generated by the contact between the gas fuel F ejected from the sub-hole 34 and the primary air A1 can be suppressed.

[0050] Incidentally, in the first embodiment, two main holes 32 and two sub-holes 34 were formed in the tip 26 of the nozzle 20. However, the present disclosure is not limited to this form as long as the main ejection part 28 can eject more gas fuel F than the sub-ejection part 30. In some embodiments, one or more than three main holes 32 are formed in the tip 26 of the nozzle 20. In some embodiments, one or more than three sub-holes 34 are formed in the tip 26 of the nozzle 20.

[0051] FIG. 8 is a diagram showing the configuration of the tip 26 of the nozzle 20 according to some embodiments. In the form illustrated in FIG. 8, the main ejection part 28 includes a plurality of main holes 32 that are more in number than the number of sub-holes 34. In this case, even if the main holes 32 are smaller in diameter than the sub-holes 34 or have the same diameter as the sub-holes 34, the main ejection part 28 can eject more gas fuel F than the sub-ejection part 30.

[0052] <Second Embodiment> The gas burner 4 according to the second embodiment of the present disclosure will be described. The second embodiment is a limitation of the shape of the main hole 32 according to the first embodiment. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0053] FIG. 9 is a diagram showing the configuration of the tip 26 of the nozzle 20 according to the second embodiment. In the second embodiment, as illustrated in FIG. 9, in a front view, the main hole 32 has an elliptical shape having a longitudinal direction along the vertical direction D2. When the length of the major axis (longitudinal direction) of the main hole 32 is L and the length of the minor axis (lateral direction) of the main hole 32 is W, 2×W < L is satisfied. For the sake of simplicity of explanation, it is assumed that the first main hole 32A and the second main hole 32B have the same shape and the same area as each other.

[0054] According to the second embodiment, it is possible to suppress the primary air A1 or the secondary air A2 from flowing into the region R (see FIG. 9) inside the nozzle 20 in the radial direction of the nozzle 20 from the gas fuel F ejected from the main hole 32. That is, the mixing of hydrogen and oxygen can be delayed, and the generation of NOx can be further suppressed.

[0055] In the second embodiment, the main hole 32 had an elliptical shape, but the present disclosure is not limited to this form. In a modified example of the second embodiment, as illustrated in FIG. 10, the main hole 32 has an arc shape (wing shape). The shape of the main hole 32 is formed based on a camber line 63 (center line) that passes through one end 60 on one side in the longitudinal direction of the main hole 32 and the other end 62 on one side in the longitudinal direction, and protrudes to the side opposite to the axis O side of the nozzle 20. Among the shape of the main hole 32, a line that connects one end 60 and the other end 62 of the main hole 32 and is located on the side opposite to the axis O side of the nozzle 20 with respect to the camber line 63 is defined as an outer line 64, and a line located on the axis O side of the nozzle 20 with respect to the camber line 63 is defined as an inner line 66. When the length of the longest straight line 70 among the straight lines that are orthogonal to the camber line 63 and connect the outer line 64 and the inner line 66 is W, and the length of the camber line 63 is L, 2×W < L is satisfied.

[0056] <Third Embodiment> The gas burner 4 according to the third embodiment of the present disclosure will be described. In the third embodiment, unlike the first embodiment, the ejection direction D4 of the main hole 32 is oriented in a direction intersecting the secondary air outlet 40. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0057] FIG. 11 is a diagram schematically showing the configuration of the gas burner according to the third embodiment. In the third embodiment, as illustrated in FIG. 11, the main ejection part 28 includes two main holes 32. The first main hole 32C (32) is located on the side opposite to the second main hole 32D (32) across the axis O of the nozzle 20 in the vertical direction D2. The first main hole 32C is located above the axis O of the nozzle 20, and the second main hole 32D is located below the axis O of the nozzle 20.

[0058] In the first embodiment, as illustrated in FIG. 11, the sub-ejection part 30 includes two sub-holes 34. The first sub-hole 34C (34) is located on the side opposite to the second sub-hole 34D (34) across the axis O of the nozzle 20 in the left-right direction D3. The first sub-hole 34C is located on the left side of the axis O of the nozzle 20, and the second sub-hole 34D is located on the right side of the axis O of the nozzle 20.

[0059] The first main hole 32C and the second main hole 32C are located between the first sub-hole 34C and the second sub-hole 34D in the left-right direction D3. The first sub-hole 34C and the second sub-hole 34D are located between the first main hole 32C and the second main hole 32D in the vertical direction D2.

[0060] The first main hole 32C is larger in diameter than the first sub-hole 34C and the second sub-hole 34D, respectively. The second main hole 32D is larger in diameter than the first sub-hole 34C and the second sub-hole 34D, respectively. The first main hole 32C and the second main hole 32D are of the same diameter. The first sub-hole 34C and the second sub-hole 34D are of the same diameter. In this way, the total opening area of ​​the main holes 32 is larger than the total opening area of ​​the sub-holes 34, and the main ejection section 28 is able to eject more gas fuel F than the sub-ejection section 30.

[0061] In the third embodiment, as illustrated in Figure 11, in a front view, the ejection direction D4 of the main hole 32 is oriented in a direction intersecting the secondary air outlet 40. In the embodiment illustrated in Figure 11, the ejection direction D4 of the first main hole 32C is upward, and the ejection direction D4 of the second main hole 32D is downward. The ejection direction D5 of the first sub-hole 34C is to the left, and the ejection direction D5 of the second sub-hole 34D is to the right. In some embodiments, the tip portion 26 of the nozzle 20 is configured to rotate about the axis O of the nozzle 20 so that it is possible to switch whether or not the ejection direction D4 of the main hole 32 is oriented in a direction intersecting the secondary air outlet 40.

[0062] Figure 12 is a diagram illustrating the layout of the secondary air outlet 40 according to the third embodiment. As shown in Figure 12, a virtual line 72 is extended linearly from the axis O of the nozzle 20 along the vertical direction D2. The point where this virtual line 72 intersects the periphery of the primary air outlet 36 is defined as the first intersection 74. Furthermore, the first point where this virtual line 72 intersects the periphery of the secondary air outlet 40 is defined as the second intersection 76. In the embodiment illustrated in Figure 12, the second intersection 76 is the first point where the virtual line 72 intersects the periphery of the inner outlet 42. If the distance between the first intersection 74 and the axis O of the nozzle 20 is r, and the distance between the second intersection 76 and the axis O of the nozzle 20 is d, then 2 × r ≤ d is satisfied.

[0063] According to the third embodiment, the secondary air outlet 40 is spaced apart from the tip 26 of the nozzle 20 such that 2 × r ≤ d is satisfied, so that contact between the gaseous fuel F ejected from the main hole 32 and the secondary air A2 or low-oxygen secondary air A3 flowing out from the secondary air outlet 40 can be delayed. As a result, the mixing of hydrogen and oxygen is slowed down, which suppresses the temperature rise in the combustion space 6 and suppresses the generation of NOx.

[0064] In this disclosure, as illustrated in Figure 2, the furnace 2 has a rectangular combustion space 6, and each of the four gas burners 4 is provided in the furnace 2 to inject gaseous fuel F into the rectangular corners 21 of the combustion space 6. However, this disclosure is not limited to this embodiment. Figures 13A, 13B, and 13C are schematic diagrams showing the internal configuration of the furnace 2 according to several embodiments.

[0065] In some embodiments, as illustrated in Figure 13A, each of the four gas burners 4 (4A, 4B, 4C, 4D) is arranged to perform swirling combustion, where the flame X swirls in the central part 23 of the combustion space 6 when the furnace 11 is viewed from above. The first gas burner 4A is located on the wall surface of the first furnace wall 8. The second gas burner 4B is located on the wall surface of the second furnace wall 10. The third gas burner 4C is located on the wall surface of the third furnace wall 12. The fourth gas burner 4D is located on the wall surface of the fourth furnace wall 14.

[0066] In some embodiments, as illustrated in Figure 13B, the combustion space 6 has an octagonal shape. The furnace 2 includes a first corner portion 82 connecting one end 16 of the first furnace wall 8 to one end 80 of the third furnace wall 12 on the first furnace wall 16 side, a second corner portion 86 connecting the other end 84 of the third furnace wall 12 on the second furnace wall 10 side to one end 18 of the second furnace wall 10, a third corner portion 90 connecting the other end 19 of the second furnace wall 10 to the other end 88 of the fourth furnace wall 14 on the second furnace wall 10 side, and a fourth corner portion 94 connecting one end 92 of the fourth furnace wall 14 on the first furnace wall 8 side to the other end 17 of the first furnace wall 8. The combustion space 6 of the furnace 2 is formed in an octagonal shape by being surrounded by the first furnace wall 8, the second furnace wall 10, the third furnace wall 12, the fourth furnace wall 14, the first corner section 82, the second corner section 86, the third corner section 90, and the fourth corner section 94. The first gas burner 4A is located on the wall surface of the fourth corner section 94. The second gas burner 4B is located on the wall surface of the second corner section 86. The third gas burner 4C is located on the wall surface of the first corner section 82. The fourth gas burner 4D is located on the wall surface of the third corner section 90.

[0067] In some embodiments, the combustion space 6 has a rectangular shape, as illustrated in Figure 13C. In the embodiment illustrated in Figure 13C, the first furnace wall 8 and the second furnace wall 10 each form the shorter sides of the rectangular combustion space 6, and the third furnace wall 12 and the fourth furnace wall 14 each form the longer sides of the rectangular combustion space 6. The furnace 2 is equipped with eight gas burners 4, and four of the gas burners 4 are arranged to cause swirling combustion of the flame X. In the embodiment illustrated in Figure 13, two flames X are causing swirling combustion of the eight gas burners 4. Each of the eight gas burners 4 is located on either the wall surface of the third furnace wall 12 or the wall surface of the fourth furnace wall 14.

[0068] The contents described in each of the above embodiments can be understood, for example, as follows:

[0069] [1] The gas burner (4) relating to this disclosure is A gas burner for burning a gaseous fuel (F) containing hydrogen, A nozzle (20) having a tip portion (26) formed therein, the nozzle (20) having a main ejection portion (28) for ejecting the gas fuel and including at least one main hole (32), and a secondary ejection portion (30) for ejecting a smaller amount of the gas fuel than the main ejection portion and including at least one secondary hole (34), In a front view along the axial direction (D1) of the nozzle, a primary air passage section (22) surrounds the tip of the nozzle and forms a primary air outlet (36) through which primary air (A1) flows out, In the aforementioned front view, the system includes a secondary air passage section (24) located above or below the primary air outlet and forming a secondary air outlet (40) through which secondary air (A2) flows out, In the front view, the ejection direction (D5) of the at least one sub-hole is oriented in a direction intersecting the secondary air outlet, and the ejection direction (D4) of the at least one main hole is oriented in a direction not intersecting the secondary air outlet.

[0070] Hydrogen burns faster than components found in conventional gaseous fuels. Therefore, when hydrogen is included in the gaseous fuel, the amount of gaseous fuel used to maintain the flame of the gas burner can be reduced. On the other hand, because hydrogen and oxygen mix rapidly, the temperature of the combustion space where the gaseous fuel is burned rises rapidly, promoting the generation of nitrogen oxides (NOx). According to the configuration described in [1] above, the small amount of gaseous fuel ejected from the sub-hole of the sub-injector can be quickly brought into contact with the secondary air flowing out from the secondary air outlet, thereby improving flame retention. In other words, flame retention can be ensured with a small amount of gaseous fuel. Furthermore, the large amount of gaseous fuel ejected from the main hole of the main injection unit comes into contact with the secondary air flowing out from the secondary air outlet later than the gaseous fuel ejected from the sub-hole. In other words, the gaseous fuel ejected from the main hole flows into a region with a relatively low oxygen concentration, away from the tip of the nozzle. Therefore, the mixing of hydrogen and oxygen is slowed down, slow combustion is promoted, the temperature rise in the combustion space is suppressed, and the generation of NOx can be suppressed. Therefore, it is possible to achieve a suitable combustion state (ensuring flame retention and suppressing NOx generation) when using gaseous fuels containing hydrogen.

[0071] [2] In some embodiments, in the configuration described in [1] above, The secondary air outlet includes an inner outlet (42) and an outer outlet (44) located further away from the primary air outlet than the inner outlet. The aforementioned outer outlet is configured to allow the secondary air to flow out. The inner outlet is configured to discharge low-oxygen secondary air (A3) with a lower oxygen concentration than the secondary air discharged from the outer outlet.

[0072] According to the configuration described in [2] above, the low-oxygen secondary air flowing out from the inner outlet is brought into contact with the hydrogen gas fuel ejected from the main hole, prior to the secondary air flowing out from the outer outlet. This further slows down the mixing of hydrogen and oxygen and further suppresses the temperature rise in the combustion space.

[0073] [3] In some embodiments, in the configuration described in [1] or [2] above, When the tip of the nozzle is viewed along the vertical direction (D2), the angle formed by the ejection direction of the main hole and the axial direction of the nozzle is defined as θ1. When the tip of the nozzle is viewed along directions perpendicular to the axial direction and the vertical direction of the nozzle, if the angle formed by the ejection direction of the sub-hole and the axial direction of the nozzle is θ2, The condition θ1 < θ2 is satisfied.

[0074] According to the configuration described in [3] above, it is possible to accelerate the contact between the small amount of gas fuel ejected from the secondary hole of the secondary ejection section and the secondary air, while delaying the contact between the large amount of gas fuel ejected from the main hole of the main ejection section and the secondary air.

[0075] [4] In some embodiments, in the configuration described in [3] above, The nozzle is further provided with a flame holder (50) having a flame-holding surface (52) that is provided at the tip of the nozzle and moves away from the axis of the nozzle as it approaches the primary air outlet, If the angle formed by the flame-holding surface and the axial direction of the nozzle is θ3, The condition satisfies θ2 ≤ θ3.

[0076] According to the configuration described in [4] above, damage to the flame holder caused by gas fuel ejected from the secondary holes of the secondary ejection section (more specifically, the flame generated by the contact between the gas fuel ejected from the secondary holes and the primary air) can be suppressed.

[0077] [5] In some embodiments, in the configuration described in [3] or [4] above, The conditions 15 degrees < θ1 < 45 degrees are met.

[0078] When θ1 exceeds 45 degrees, the potential for combustion oscillations due to pressure fluctuations in the combustion space increases. Also, when θ1 falls below 15 degrees, excessive flame lengthening occurs, affecting the heat absorption characteristics. For this reason, the configuration described in [5] above can suppress combustion oscillations and suppress the temperature rise in the combustion space through slow combustion with an appropriate flame lengthening.

[0079] [6] In some embodiments, in the configuration described in [3] or [4] above, The conditions 35 degrees < θ² < 55 degrees are met.

[0080] If θ2 exceeds 55 degrees, the flame-holding effect near the flame holder becomes too strong, which increases the burnout potential of the flame holder and may promote the generation of NOx. Conversely, if θ2 is less than 35 degrees, the flame-holding effect weakens and the vibration potential increases. Therefore, the configuration described in [6] above can effectively suppress combustion vibration, flame holder damage, and NOx generation in a balanced manner.

[0081] [7] In some embodiments, in the configuration described in any one of [1] to [6] above, In the front view, the at least one main hole has a longitudinal shape, and if the length of the at least one main hole in the longitudinal direction is L and the length of the at least one main hole in the transverse direction is W, It satisfies 2×W < L.

[0082] According to the configuration described in [7] above, it is possible to suppress the primary air or the secondary air from flowing into the region inside the nozzle in the radial direction of the nozzle from the gas fuel ejected from the main hole. That is, the mixing of hydrogen and oxygen can be delayed, and the generation of NOx can be further suppressed.

[0083] [8] In some embodiments, in the configuration described in any one of [1] to [7] above, The main ejection part includes at least one main hole having a larger diameter than the at least one sub-hole.

[0084] According to the configuration described in [8] above, the main ejection part can realize the ejection of a larger amount of gas fuel than the sub-ejection part.

[0085] [9] In some embodiments, in the configuration described in any one of [1] to [8] above, The main ejection part includes the plurality of main holes having a number larger than the number of the at least one sub-hole.

[0086] According to the configuration described in [9] above, the main ejection part can realize the ejection of a larger amount of gas fuel than the sub-ejection part.

[0087]

[10] In some embodiments, in the configuration described in any one of [1] to [9] above, The at least one main hole includes a first main hole (32A) and a second main hole (32B), In the front view, the first main hole is located on the opposite side of the second main hole across the axis of the nozzle in the left-right direction (D3), The ejection direction of the first main hole is oriented to be opposite to the ejection direction of the second main hole.

[0088] According to the configuration described in

[10] above, the main ejection part can eject the gas fuel widely in the left-right direction.

[0089]

[11] In some embodiments, in the configuration described in any one of [1] to

[10] above, The at least one sub-hole includes a first sub-hole (34A) and a second sub-hole (34B), In the aforementioned front view, the first sub-hole is located on the opposite side of the nozzle axis in the vertical direction from the second sub-hole, The ejection direction of the first sub-hole is oriented to be opposite to the ejection direction of the second sub-hole.

[0090] According to the configuration described in

[11] above, the auxiliary ejector can eject gaseous fuel in both the vertical and vertical directions.

[0091]

[12] The gas burner relating to this disclosure is A gas burner for burning gaseous fuel containing hydrogen, A nozzle having a main ejection section for ejecting the gaseous fuel and including at least one main hole, and a secondary ejection section for ejecting a smaller amount of the gaseous fuel than the main ejection section and including at least one secondary hole, formed at its tip, In a front view along the axial direction of the nozzle, a primary air passage section surrounds the tip of the nozzle and forms a primary air outlet through which primary air flows, In the aforementioned front view, the system includes a secondary air passage section located above or below the primary air outlet and forming a secondary air outlet from which secondary air flows out, When a virtual line (72) is extended in a straight line vertically from the axis of the nozzle, Let r be the distance between the first intersection (74) where the imaginary line intersects the periphery of the primary air outlet and the axis of the nozzle, and let d be the distance between the second intersection (76) where the imaginary line first intersects the periphery of the secondary air outlet and the axis of the nozzle. Satisfying 2 × r ≤ d, In the aforementioned front view, the ejection direction of the at least one main hole is oriented in a direction intersecting the secondary air outlet.

[0092] According to the configuration described in

[12] above, the secondary air outlet is spaced apart from the tip of the nozzle where the main injection section is formed such that 2 × r ≤ d is satisfied, so that contact between the gaseous fuel ejected from the main hole of the main injection section and the secondary air flowing out from the secondary air outlet can be delayed. As a result, the mixing of hydrogen and oxygen is slowed down, which suppresses the rise in temperature of the combustion space and suppresses the generation of NOx.

[0093]

[13] In some embodiments, in the configuration described in any one of [1] to

[12] above, The gas burner is a rectangular burner in which the end face facing the furnace has a longitudinal direction along the vertical direction.

[0094] According to the configuration described in

[13] above, any one of the configurations described in [1] to

[12] above can be applied to a rectangular burner.

[0095]

[14] In some embodiments, the combustion equipment is Fireplace (2), The furnace is provided with a gas burner according to any one of [1] to

[13] above.

[0096] According to the configuration described in

[14] above, even when a gas burner using a gas fuel containing hydrogen is provided, a suitable combustion state can be maintained inside the furnace. [Explanation of Symbols]

[0097] 1. Combustion equipment 2 Furnace 4 Gas burners 20 nozzles 22 Primary airflow channel 24 Secondary airflow channel section 26 Nozzle tip 28 Main spout 30 Secondary ejection part 32 Main holes 32A First Main Hole 32B 2nd main hole 34 Secondary hole 34A 1st secondary hole 34B 2nd subhole 36 Primary air outlet 40 Secondary air outlet 42 Inner exit 44 External exit 50 Flame holder 52 Flame holding surface 72 virtual lines 74 First Intersection 76 Second Intersection A Combustion air A1 Primary air A2 Secondary air A3 Low-oxygen secondary air D1 Axial direction D2 Vertical direction D3 Left and Right Direction D4 Main hole ejection direction D5 Sub-hole ejection direction F Gas fuel G exhaust gas O Nozzle axis

Claims

1. A gas burner for burning gaseous fuel containing hydrogen, A nozzle having a main ejection section for ejecting the gaseous fuel and including at least one main hole, and a secondary ejection section for ejecting a smaller amount of the gaseous fuel than the main ejection section and including at least one secondary hole, formed at its tip, In a front view observed along the axial direction of the nozzle, a cylindrical primary air passage section is provided, which is arranged coaxially with the nozzle, surrounds the tip of the nozzle, and forms a primary air outlet through which primary air flows out. In the aforementioned front view, the system comprises a pair of secondary air passage sections, each positioned separately above and below the primary air outlet, and forming a pair of secondary air outlets through which secondary air flows out. In the front view, the ejection direction of the at least one sub-hole is oriented upward or downward so as to intersect with the secondary air outlet, and the ejection direction of the at least one main hole is oriented to the left or to the right so as not to intersect with the secondary air outlet. Gas burner.

2. The secondary air outlet includes an inner outlet and an outer outlet located further away from the primary air outlet than the inner outlet. The aforementioned outer outlet is configured to allow the secondary air to flow out. The inner outlet is configured to discharge low-oxygen secondary air with a lower oxygen concentration than the secondary air discharged from the outer outlet. The gas burner according to claim 1.

3. When the tip of the nozzle is viewed along the vertical direction, the angle formed by the ejection direction of the main hole and the axial direction of the nozzle is defined as θ1. When the tip of the nozzle is viewed along directions perpendicular to the axial direction and the vertical direction of the nozzle, if the angle formed by the ejection direction of the sub-hole and the axial direction of the nozzle is θ2, Satisfying θ1 < θ2, A gas burner according to claim 1 or 2.

4. The nozzle is further provided with a flame holder having a flame-holding surface that is provided at the tip of the nozzle and moves away from the axis of the nozzle as it approaches the primary air outlet, If the angle formed by the flame-holding surface and the axial direction of the nozzle is θ3, Satisfying θ2 ≤ θ3, The gas burner according to claim 3.

5. Satisfying the conditions 15 degrees < θ1 < 45 degrees, The gas burner according to claim 3 or 4.

6. Satisfying the conditions 35 degrees < θ² < 55 degrees, The gas burner according to claim 3 or 4.

7. In the front view, the at least one main hole has a longitudinal shape, and if the length of the at least one main hole in the longitudinal direction is L and the length of the at least one main hole in the transverse direction is W, Satisfying 2 × W < L, A gas burner according to any one of claims 1 to 6.

8. The main ejection section includes at least one main hole that is larger in diameter than the at least one sub-hole. A gas burner according to any one of claims 1 to 7.

9. The main ejection section includes a number of main holes greater than the number of at least one sub-hole, A gas burner according to any one of claims 1 to 8.

10. The at least one main hole includes a first main hole and a second main hole, In the aforementioned front view, the first main hole is located on the opposite side from the second main hole in the left-right direction, with respect to the axis of the nozzle. The ejection direction of the first main hole is oriented to be opposite to the ejection direction of the second main hole. A gas burner according to any one of claims 1 to 9.

11. The at least one sub-hole includes a first sub-hole and a second sub-hole, In the aforementioned front view, the first sub-hole is located on the opposite side of the nozzle axis in the vertical direction from the second sub-hole, The ejection direction of the first sub-hole is oriented to be opposite to the ejection direction of the second sub-hole. A gas burner according to any one of claims 1 to 10.

12. The gas burner is a rectangular burner in which the end face facing the furnace has a rectangular shape with its longitudinal direction aligned with the vertical direction. A gas burner according to any one of claims 1 to 11.

13. A fire pit and The furnace is provided with a gas burner according to any one of claims 1 to 12, Combustion equipment.

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