Low-NOx premixing hydrogen burner

Abstract

A low NOx premixed hydrogen burner includes: a plenum chamber including an inlet tube and an outlet tube for mixing hydrogen and combustion air introduced through the inlet tube to generate a premixed gas for flame formation, where the plenum chamber has a diameter greater than a diameter of the inlet tube and a diameter of the outlet tube, and the length of the inflation chamber is greater than the diameter of the inflation chamber.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent Application No. 10-2023-0114849 filed on August 30, 2023 in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to a low NOx premixed hydrogen burner, and more particularly to a low NOx premixed hydrogen burner structure, which can reduce nitrogen oxides discharged by the burner using hydrogen as fuel. Background Art

[0003] Efforts are being made around the world to achieve carbon neutrality in production plants, and in the field of electricity, electricity has been developed through various renewable energy sources. However, in automobile production plants, painting / PT plants use a large amount of energy that burns liquefied natural gas (LNG), such as ovens and booth air conditioner burners, which is directly related to greenhouse gas emissions. Therefore, in order to achieve carbon neutrality in production plants, hydrogen burners that do not produce greenhouse gases are being developed to replace existing LNG burners.

[0004] However, for hydrogen burners, a combustion method using a premixing method is used, which is relatively conducive to low NOx environmental regulations. However, since nitrogen oxides are produced due to the high flame temperature of hydrogen, it is difficult to meet the requirements of environmental regulations. In addition, flashback and misfires in hydrogen combustion will limit the stable operating area. Summary of the invention

[0005] The present invention attempts to provide a low NOx premixed hydrogen burner structure, which can effectively reduce NOx emissions and expand the safe operating range of combustion.

[0006] An exemplary embodiment of the present invention provides a low NOx premixed hydrogen burner, which includes a plenum chamber, wherein the plenum chamber includes an inlet pipe and an outlet pipe, and is configured to mix hydrogen and combustion air introduced through the inlet pipe to generate a premixed gas for flame formation, wherein the diameter of the plenum chamber is larger than the diameter of the inlet pipe and the diameter of the outlet pipe, and the length of the plenum chamber is larger than the diameter of the plenum chamber.

[0007] The low NOx premixed hydrogen burner may also include a hydrogen supply pipe and a combustion air supply pipe; the hydrogen supply pipe is connected to the inlet pipe of the inflation chamber and is configured to supply hydrogen, and the combustion air supply pipe is connected to the inlet pipe of the inflation chamber and is configured to supply combustion air for combustion.

[0008] The low NOx premixed hydrogen burner may further include an external cooling air supply pipe connected to the outlet pipe of the plenum chamber and configured to flow external cooling air along the periphery of the outlet pipe to cool the premixed gas discharged from the plenum chamber.

[0009] The air-filled chamber may be formed in a cylindrical shape.

[0010] The length-to-radius ratio (AR) of the plenum may be about 6.7 to about 6.9.

[0011] The plenum may have a length to radius ratio (AR) of less than about 12.9.

[0012] The diameter of the resulting plenum can be more than twice the diameter of the upstream pipe.

[0013] The plenum chamber may be formed as a diffuser-type or a nozzle-type having different diameters between an inlet and an outlet.

[0014] The outer cooling air supply pipe may be installed in a ring shape to surround the outer circumference of the plenum chamber outlet pipe.

[0015] The inner surface of the outer cooling air supply pipe may be connected to the outer surface of the plenum outlet pipe via a reducer so that the cooling air supply is not biased toward a specific direction.

[0016] The outlet end of the plenum outlet pipe may project from the outlet end of the external cooling air supply pipe by a recess length Lc, and the recess length Lc may be formed to be a minimum value.

[0017] The diameter of the outer cooling air supply pipe outlet may be formed to generate an air supply flow rate of about 15 m / sec to about 30 m / sec.

[0018] The low NOx premixed hydrogen burner may also include: an internal cooling air supply pipe, which is installed to extend through the interior of the plenum to reach the outlet pipe of the plenum and is configured to allow external cooling air to flow through the plenum and cool the premixed gas in the plenum.

[0019] The outlet end of the inner cooling air supply pipe may be formed to be in the same vertical line as the outlet end of the outlet pipe of the plenum chamber or to protrude from the outlet end of the outlet pipe of the plenum chamber.

[0020] An outlet end of the inner cooling air supply pipe may be formed in a diffuser shape.

[0021] The outlet end of the inner cooling air supply pipe may be formed to protrude from the outlet end of the plenum outlet pipe by a length of one third or less of a length of a flame formed from the outlet end of the inner cooling air supply pipe.

[0022] The flow rate and pressure of the inner cooling air in the inner cooling air supply pipe may be formed to be greater than the flow rate and pressure of the premixed gas of the hydrogen burner at full load.

[0023] The inner cooling air supply duct may include a single inlet and a plurality of outlets.

[0024] In an exemplary embodiment, a low NOx premixed hydrogen burner is provided. The burner includes: a plenum chamber, the plenum chamber including an inlet pipe and an outlet pipe, configured to mix hydrogen introduced through the inlet pipe with combustion air to produce a premixed gas for flame formation. The outer cooling air supply pipe can be installed in an annular shape to surround the outer periphery of the outlet pipe of the plenum chamber. The inner cooling air supply pipe can be installed to extend through the interior of the plenum chamber to reach the outlet pipe of the plenum chamber.

[0025] The outlet end of the plenum outlet pipe may project over the outlet end of the outer cooling air supply pipe. The outlet end of the inner cooling air supply pipe is formed to be in the same vertical line as the outlet end of the plenum outlet pipe or to project over the outlet end of the plenum outlet pipe.

[0026] According to an embodiment of the present invention, the mixing performance of the pre-mixed gas can be improved by stabilizing the internal flow and forming a forced vortex in the charging chamber for producing a pre-mixed gas mixed with hydrogen and combustion-supporting air, and stable combustion can be achieved by increasing the range of stable combustion.

[0027] In addition, the premixed flame can be cooled by supplying external cooling air and internal cooling air through ducts installed around the plenum, thereby reducing the flame hot spot and flame length.

[0028] In addition, the exposure time in high temperature areas can be reduced, thereby reducing the amount of NOx generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a diagram schematically illustrating a low NOx premixed hydrogen burner according to an exemplary embodiment of the present invention.

[0030] Figure 2 is a diagram schematically illustrating a hydrogen burner system including a low NOx premixed hydrogen burner according to an exemplary embodiment of the present invention.

[0031] Figure 3 is a diagram schematically showing the flow of premixed gas inside a plenum of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0032] Figure 4 is a graph showing the effect of increasing the plenum chamber of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0033] Figure 5 is a diagram showing an outlet of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0034] Figure 6 : is a diagram showing a pipe reducing state between an outer cooling air supply pipe and a plenum outlet pipe of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0035] Figure 7 is a diagram showing the appearance of a premixed flame according to a difference in a setback length Lc between an outlet end of an outer cooling air supply pipe and an outlet end of a plenum outlet pipe of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0036] Figure 8 It shows that according to Figure 7 Graph showing the effect of differences in setback length Lc on NOx generation.

[0037] Fig. 9 is a diagram showing a premixed flame state of internal and external cooling air supply conditions of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0038] Fig.10 : is a diagram showing a state in which an inner cooling air supply pipe of a low NOx premixed hydrogen burner according to an embodiment of the present invention protrudes beyond an outlet end of a plenum outlet pipe.

[0039] Fig.11A and Fig. 11B1 is a graph showing the relationship between the wake temperature and NOx concentration of the premixed hydrogen burner and the supplied hydrogen when the premixed gas is cooled using only external cooling air or using both external cooling air and internal cooling air in a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0040] Fig. 12A and Fig. 12B 1 is a graph showing the relationship between the tail flow temperature and NOx concentration of the premixed hydrogen burner relative to the supplied cooling air in a low NOx premixed hydrogen burner according to an embodiment of the present invention, when the premixed gas is cooled by using both external cooling air and internal cooling air or only external cooling air.

[0041] Fig.13 is a diagram showing a plenum chamber of a low NOx premixed hydrogen burner according to another embodiment of the present invention.

[0042] Fig.14 is a diagram showing an inner cooling air supply pipe of a low NOx premixed hydrogen burner according to another embodiment of the present invention. DETAILED DESCRIPTION

[0043] In the following detailed description, only certain exemplary embodiments of the present invention are shown and described by way of illustration. However, the present invention can be implemented in many ways and is not limited to the following embodiments.

[0044] Furthermore, among the plurality of exemplary embodiments, constituent elements having the same configuration will be representatively described in one exemplary embodiment by using the same reference numerals, and other configurations different from one exemplary embodiment will be described in other exemplary embodiments.

[0045] It should be noted that the drawings are schematic and not drawn to scale. The relative sizes and proportions of the components in the drawings are enlarged or reduced to make the drawing clearer and more convenient, and any size is illustrative only and not restrictive. In addition, for the same structure, element or component appearing in two or more figures, the same reference numerals are used to represent similar features. When a component is referred to as being "above" or "on" another component, a component may be directly on the other component, or there may be other components between the one component and the other component.

[0046] An exemplary embodiment of the present invention specifically illustrates an embodiment of the present invention. Therefore, it is expected that various modifications will be made to the drawings. Therefore, the embodiments of the present invention are not limited to the specific form of the illustrated area, but also include form modifications such as those performed by manufacturing.

[0047] Hereinafter, referring to the accompanying drawings, a low NOx premixed hydrogen burner according to an exemplary embodiment of the present invention will be described in detail.

[0048] Figure 1 is a diagram schematically showing a low NOx premixed hydrogen burner according to an exemplary embodiment of the present invention, Figure 3 is a diagram schematically showing the flow of premixed gas inside a plenum of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0049] Reference Figure 1 , a low NOx premixed hydrogen burner according to an exemplary embodiment of the present invention may include a plenum chamber 10 .

[0050] The plenum 10 may have an inlet pipe 12 into which hydrogen and combustion air flow and an outlet pipe 14 from which premixed gas of hydrogen and combustion air is discharged. The length of the plenum 10 may be set to be greater than the diameter of the plenum 10.

[0051] In addition, the plenum 10 may be formed in a cylindrical shape. A premixed gas of hydrogen and combustion-supporting air may be generated in the cylindrical space between the inlet pipe 12 and the outlet pipe 14. In this case, the diameter of the plenum 10 may be formed to be larger than both the diameter of the inlet pipe 12 and the diameter of the outlet pipe 14, and may be formed to be more than twice the diameter of the upstream pipe.

[0052] The low NOx premixed hydrogen burner according to an embodiment of the present invention may also include: a hydrogen supply pipe 20 connected to the inlet pipe of the inflation chamber 10, a combustion air supply pipe 30 connected to the inlet pipe of the inflation chamber 10 separately from the hydrogen supply pipe 20, and an external cooling air supply pipe 40 connected to the outlet pipe 14 of the inflation chamber 10.

[0053] like Figure 3 As shown, hydrogen and combustion air can be introduced and mixed to form a premixed gas in the plenum 10. The hydrogen and combustion air are uniformly mixed in the plenum 10 and generate forced vortices to form a stable premixed gas at a constant flow rate and pressure.

[0054] Hydrogen can be supplied to the interior of the plenum 10 by pressure, and combustion air can be supplied by an external blower 32, thereby generating a forced vortex to stabilize the mixing and flow of the premixed gas. In addition, in order to generate a premixed gas with a stable flow rate and pressure, the ratio of the length to the radius of the plenum 10 can be set to about 6.7 to about 6.9.

[0055] The hydrogen supply pipe 20 may be connected to the inlet pipe 12 of the plenum 10, and receives hydrogen from the external hydrogen tank 2, and supplies the received hydrogen to the inside of the plenum 10. The hydrogen supply pipe 20 is arranged in a direction parallel to the inlet pipe 12 of the plenum 10, and is arranged to pass through the inside of the combustion-supporting air supply pipe 30. The outlet of the hydrogen supply pipe 20 may be formed as the same outlet as the outlet of the combustion-supporting air supply pipe 30.

[0056] Further, the combustion-supporting air supply pipe 30 may be connected to the inlet pipe 12 of the plenum 10, and receive the combustion-supporting air for combustion through the external blower 32, and supply the received combustion-supporting air to the interior of the plenum 10. The combustion-supporting air supply pipe 30 is arranged to be perpendicular to the inlet pipe 12 of the plenum 10, and may form an outlet substantially the same as the outlet of the hydrogen supply pipe 20. In this way, the hydrogen supplied from the hydrogen supply pipe 20 and the combustion-supporting air supplied from the combustion-supporting air supply pipe 30 flow to the interior of the plenum 10 through the inlet pipe 12 of the plenum 10 together.

[0057] The external cooling air supply pipe 40 may be connected to the outlet pipe 14 of the plenum 10 and may cool the premixed gas formed inside the plenum 10. To this end, the external cooling air supply pipe 40 may flow the external cooling air along the outer circumference of the outlet pipe 14 of the plenum 10. The external cooling air may be supplied to the external cooling air supply pipe 40 by an external blower 42.

[0058] The outer cooling air supply pipe 40 may be installed in an annular shape to surround the outer circumference of the outlet pipe 14 of the plenum 10. The outer cooling air supply pipe 40 may be arranged in a direction perpendicular to the outlet pipe 14 of the plenum 10, and the outlet of the outer cooling air supply pipe 40 may be formed at a position substantially similar to the outlet of the outlet pipe 14 of the plenum 10.

[0059] On the other hand, the plenum 10 may further include an inner cooling air supply pipe 50, which is installed to extend through the interior of the plenum 10 to reach the outlet pipe 14 of the plenum 10. The inner cooling air supply pipe 50 may be inserted into the interior from one outer side of the plenum 10 in a direction perpendicular to the longitudinal direction of the plenum 10, and may be bent inside the plenum 10 to extend in the longitudinal direction of the plenum 10. The outlet of the inner cooling air supply pipe 50 may be formed at a position substantially similar to the outlet of the outlet pipe 14 of the plenum 10 and the outlet of the outer cooling air supply pipe 40.

[0060] Figure 2 is a diagram schematically showing a hydrogen burner system including a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0061] Reference Figure 2 The hydrogen supply pipe 20 can receive hydrogen from the hydrogen tank 2 and deliver the received hydrogen to the gas filling chamber 10. In the hydrogen tank 2, a hydrogen supply regulator 3 is connected and installed to control the hydrogen supply pressure of the hydrogen burner, and a hydrogen metering valve 5 is connected and installed to control the flow rate of the ignition hydrogen. At the rear end of the regulator 3 and the metering valve 5, a hydrogen flow control valve 4 can be installed to control the flow rate of hydrogen supplied to the gas filling chamber 10.

[0062] A blower 32 may be installed in the combustion air supply pipe 30 to introduce combustion air from the outside and deliver the introduced air to the plenum 10. In addition, a blower 42 is installed in the external cooling air supply pipe 40 for introducing external cooling air to cool the premixed gas discharged from the plenum 10. In addition, a blower 52 is also installed in the internal cooling air supply pipe for introducing external cooling air to cool the premixed gas generated in the plenum 10.

[0063] The outlet pipe 14 of the plenum chamber 10, the outlet of the outer cooling air supply pipe 40, and the outlet of the inner cooling air supply pipe 50 may be formed at substantially the same position, and the igniter 7 is installed at these positions to generate a spark by the operation of the ignition coil 6 and the action of the hydrogen gas discharged through the metering valve 5. The spark reacts with the premixed gas discharged from the outlet pipe 14 of the plenum chamber 10 to form a hydrogen burner flame. The flame is then discharged to the outside through the combustion chamber 100.

[0064] Figure 4 is a graph showing the effect of increasing the plenum chamber of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0065] Reference Figure 4 By measuring the temperature about 10 mm behind the flame tip and measuring whether the flame is extinguished or flashes back, it can be found that for an ordinary combustion tube without an inflation chamber 10, the safe operating region where the flame is not extinguished and flashes back is about 320°C to about 650°C.

[0066] In addition, when the plenum 10 is provided and the ratio (AR) of the length of the plenum 10 to the radius is 6.8, the safe operating area is measured to be about 180° C. to about 540° C., which can ensure the widest range of the safe operating area, indicating that the flow stability is excellent. On the contrary, when the ratio (AR) of the length of the plenum 10 to the radius is about 12.9, the safe operating area is measured to be larger, but there is a risk of flashback at low loads, and the size of the burner is increased, which restricts installation.

[0067] On the other hand, when a swirl-shaped flow path is formed in the plenum 10 , the gas mixing performance may be good, but the flow stability may be difficult to ensure due to the narrow safe operation area, and it is not easy to manufacture such a shape in the plenum 10 .

[0068] Therefore, the length to radius ratio (AR) of the plenum chamber 10 of the low NOx premixed hydrogen burner according to an embodiment of the present invention may be set to about 6.7 to about 6.9.

[0069] Figure 5 is a diagram showing an outlet of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0070] Reference Figure 5 The external cooling air supply pipe 40 may include an annularly mounted duct 44 to surround the outer periphery of the outlet pipe 14 of the plenum 10, and the externally supplied cooling air may flow longitudinally along the outer periphery of the outlet pipe 14 of the plenum 10 to cool the premixed gas flowing along the outlet pipe 14 from the inside of the plenum 10.

[0071] Figure 6 is a diagram showing a pipe diameter reduction state between an outer cooling air supply pipe and a plenum chamber outlet pipe of a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0072] Reference Figure 6 The outlet of the external cooling air supply pipe 40 can form a duct 44, which is separated from the outlet pipe 14 of the inflation chamber 10, and the inner surface of the outlet of the external cooling air supply pipe 40 can be connected to the outer surface of the outlet pipe 14 of the inflation chamber 10 through a reducing pipe 46, so that the flow rate and flow velocity of the external cooling air are not biased while maintaining a constant spacing.

[0073] Figure 7 is a diagram showing the appearance of a premixed flame according to a difference in a setback length Lc between an outlet end of an outer cooling air supply pipe and an outlet end of a plenum outlet pipe of a low NOx premixed hydrogen burner according to an embodiment of the present invention, and Figure 8 It shows that according to Figure 7Graph showing the effect of differences in setback length Lc on NOx generation.

[0074] Reference Figure 7 , the outlet end of the outer cooling air supply pipe 40 can be formed to be less protruding than the outlet end of the outlet pipe 14 of the plenum 10, and the setback length Lc can be minimized. In addition, the diameter of the outlet of the outer cooling air supply pipe 40 can be formed so that the air supply flow rate is about 15 m / sec to about 30 m / sec.

[0075] Figure 8 : is a graph of the amount of NOx generated when the ratio of the setback length Lc to the diameter D of the outlet pipe 14 is a, b, c and d, where a is greater than b, b is greater than c, and d is the ratio when the outlet end of the external cooling air supply pipe 40 protrudes further than the outlet end of the outlet pipe 14 of the charging chamber 10.

[0076] like Figure 8 As shown, under the condition that the diameter D of the outlet pipe 14 of the plenum 10 is the same, it can be seen that the amount of NOx generated is the smallest when the ratio of the setback length Lc to the diameter D of the outlet pipe 14 is c. In other words, it can be seen that when the outlet end of the external cooling air supply pipe 40 does not protrude further than the outlet end of the outlet pipe 14 of the plenum 10 and the setback length Lc is the smallest, the effect of suppressing the formation of hot spots in the premixed flame is improved.

[0077] Fig. 9 is a diagram showing a premixed flame state of an inner cooling air and an outer cooling air supply condition of a low NOx premixed hydrogen burner according to an embodiment of the present invention, Fig.10 : is a diagram showing a state in which an inner cooling air supply pipe of a low NOx premixed hydrogen burner according to an embodiment of the present invention protrudes beyond an outlet end of a plenum outlet pipe.

[0078] like Fig. 9 As shown, the outlet end of the inner cooling air supply pipe 50 can be substantially on the same vertical line as the outlet end of the outlet pipe 14 of the plenum 10. The premixed gas discharged from the outlet of the outlet pipe 14 of the plenum 10 forms a triangular flame surface relative to the inner center portion. When the premixed gas passes through the flame surface, the premixed gas is burned to form high-temperature combustion gas. At this time, the flow rate of the premixed gas and the flame speed reach a balance.

[0079] The inner cooling air from the outlet of the inner cooling air supply pipe 50 can directly cool the combustion gas at the high temperature spot of the flame zone. Compared with the cooling of the outer cooling air discharged from the outlet of the outer cooling air supply pipe 40, the inner cooling air can be effectively cooled at a smaller flow rate. When the inner cooling air flow rate is too large, the premixed flame may become unstable, so it is necessary to properly distribute the supply flow rate with the outer cooling air flow rate.

[0080] Meanwhile, the flow rate and pressure of the inner cooling air in the inner cooling air supply pipe 50 may be formed to be greater than the flow rate and pressure of the premixed gas when the hydrogen burner is fully loaded. Otherwise, the inner cooling air may mix with the premixed gas, resulting in a decrease in cooling performance.

[0081] See also Fig.10 , the outlet end of the inner cooling air supply pipe 50 may protrude further than the outlet end of the outlet pipe 14 of the plenum 10 so as to cool the flame after the flame is formed. The mixing of the inner cooling air with the premixed gas will change the equivalence ratio of the premixed gas, thereby increasing the possibility of forming an unstable flame. The outlet end of the inner cooling air supply pipe 50 may be formed to protrude by about one-third or less of the length of the flame compared to the outlet end of the outlet pipe 14 of the plenum 10. Since the closer the outlet end of the inner cooling air supply pipe 50 is to the flame surface, the worse its durability is, and the more thermal fatigue may occur, the outlet end of the inner cooling air supply pipe 50 may be formed to protrude by a length less than about one-third of the flame length.

[0082] Furthermore, the outlet end of the inner cooling air supply pipe 50 may also be formed in the shape of a diffuser.

[0083] Fig.11A and Fig. 11B 1 is a graph showing the relationship between the tail flow temperature and NOx concentration of the premixed hydrogen burner and the supplied hydrogen when the premixed gas is cooled using only external cooling air or using both external cooling air and internal cooling air in a low NOx premixed hydrogen burner according to an embodiment of the present invention.

[0084] Reference Fig.11A , under the condition of the same external cooling air flow rate, the case where only external cooling air is supplied is compared with the case where both external cooling air and internal cooling air are supplied. In the latter case, the flame tail temperature may remain unchanged or increase slightly.

[0085] Reference Fig. 11B, under the condition of having the same external cooling air flow rate, comparing the case of supplying only external cooling air with the case of supplying both external cooling air and internal cooling air, it can be seen that in the latter case, the cooling efficiency of the hot zone is higher, resulting in a lower NOx concentration in the emission.

[0086] Fig. 12A and Fig. 12B 1 is a graph showing the relationship between the tail flow temperature and NOx concentration of the premixed hydrogen burner and the supplied cooling air in a low NOx premixed hydrogen burner according to an embodiment of the present invention, when the premixed gas is cooled by using both external cooling air and internal cooling air or only external cooling air.

[0087] Reference Fig. 12A , under the condition of the same inner cooling air flow rate, the flame tail temperature can be maintained when both outer cooling air and inner cooling air are supplied, or when only outer cooling air is supplied.

[0088] Reference Fig. 12B It can be seen that under the condition of the same internal cooling air flow rate, the NOx concentration emitted is higher when only the external cooling air is supplied. Therefore, it can be seen that it is beneficial to supply both the external cooling air and the internal cooling air to cool the premixed gas.

[0089] Fig.13 is a diagram showing a plenum chamber of a low NOx premixed hydrogen burner according to another embodiment of the present invention.

[0090] Reference Fig.13 The plenum 18 may be formed as a diffuser type or a nozzle type with different diameters between the inlet and the outlet. The plenum 18 may be a diffuser type with an inlet diameter smaller than an outlet diameter, or a nozzle type which is the reverse of the diffuser type. In addition to the above-mentioned shapes, the shape of the plenum 18 may also be changed for the stability of the flame.

[0091] Fig.14 is a diagram showing an inner cooling air supply pipe of a low NOx premixed hydrogen burner according to another embodiment of the present invention.

[0092] like Fig.14 As shown, the inner cooling air supply pipe 50 may include a single inlet and a plurality of outlets. That is, the inner cooling air supply pipe 50 extends from the single inlet to the interior of the plenum 10, and branches from the outlet pipe 14 of the plenum 10 into a plurality of branch pipes 52, 54 and 56 to form a plurality of outlets. The plurality of outlet ends may be formed on substantially the same vertical line as the outlet end of the outlet pipe 14 of the plenum 10, or may be formed to protrude further than the outlet end of the outlet pipe 14 of the plenum 10.

[0093] The inner cooling air supply pipe 50 may be formed into a plurality of branch pipes 52 , 54 , and 56 in the outlet pipe 14 of the plenum 10 , so that the premixed gas in the outlet pipe 14 of the plenum 10 may be cooled more effectively.

[0094] Therefore, according to an embodiment of the present invention, by stabilizing the internal flow and forming a forced vortex in the inflation chamber for generating a premixed gas of hydrogen and combustion-supporting air, the mixing performance of the premixed gas can be improved, and stable combustion can be achieved by increasing the range of stable combustion.

[0095] In addition, the premixed flame can be cooled by supplying external cooling air and internal cooling air through ducts installed around the plenum, thereby reducing flame hot spots and flame length.

[0096] In addition, the exposure time in high temperature areas can be reduced, thereby reducing the amount of NOx generated.

[0097] While the invention has been described in conjunction with what are presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims.

[0098] <Description of Reference Numerals> 2: Hydrogen tank 3: Regulator 4: Hydrogen flow control valve 5: Metering valve 6: Ignition coil 7: Ignition 10, 18: Inflatable chamber 12: Inlet pipe 14: Outlet pipe 20: Hydrogen supply pipe 30: Combustion air supply pipe 32, 42, 52: Blower 40: External cooling air supply pipe 44: Conduit 46: Reducer pipe 50: Internal cooling air supply pipe 52, 54, 56: branch pipe 100: combustion chamber

Claims

1. A low NOx premixed hydrogen burner comprising: a plenum chamber including an inlet pipe and an outlet pipe, configured to mix hydrogen gas introduced through the inlet pipe with combustion air to produce a premixed gas for flame formation, wherein the diameter of the plenum is larger than the diameter of the inlet pipe and the diameter of the outlet pipe, and The length of the air-filled chamber is greater than the diameter of the air-filled chamber.

2. The low NOx premixed hydrogen burner according to claim 1, further comprising: a hydrogen supply pipe connected to the inlet pipe of the plenum chamber and configured to supply hydrogen; as well as A combustion-supporting air supply pipe is connected to the inlet pipe of the plenum chamber and is configured to supply combustion-supporting air.

3. The low NOx premixed hydrogen burner according to claim 1, further comprising: An external cooling air supply pipe is connected to the outlet pipe of the plenum chamber and is configured to flow external cooling air along the outer circumference of the outlet pipe to cool the premixed gas discharged from the plenum chamber.

4. The low NOx premixed hydrogen burner according to claim 1, wherein: The air-filled chamber is formed in a cylindrical shape.

5. The low NOx premixed hydrogen burner according to claim 1, wherein: The plenum has a length to radius ratio AR of about 6.7 to about 6.

9.

6. The low NOx premixed hydrogen burner according to claim 1, wherein: The plenum has a length to radius ratio AR of less than about 12.

9.

7. The low NOx premixed hydrogen burner according to claim 1, wherein: The diameter of the resulting plenum is more than twice the diameter of the upstream pipe.

8. The low NOx premixed hydrogen burner according to claim 1, wherein: The plenum is formed in a diffuser type or a nozzle type having different diameters between an inlet and an outlet.

9. The low NOx premixed hydrogen burner according to claim 3, wherein: The outer cooling air supply pipe is installed in a ring shape to surround the outer circumference of the plenum chamber outlet pipe.

10. The low NOx premixed hydrogen burner according to claim 9, wherein: The inner surface of the outer cooling air supply pipe is connected to the outer surface of the plenum outlet pipe through a reducing pipe, so that the cooling air supply is not biased to a specific direction.

11. The low NOx premixed hydrogen burner according to claim 9, wherein: The outlet end of the plenum outlet pipe protrudes from the outlet end of the external cooling air supply pipe by a setback length Lc, and the setback length Lc is formed to be a minimum value.

12. The low NOx premixed hydrogen burner according to claim 9, wherein: The outer cooling air supply pipe outlet has a diameter formed to generate an air supply flow rate of about 15 m / sec to about 30 m / sec.

13. The low NOx premixed hydrogen burner according to claim 1, further comprising: An inner cooling air supply pipe is installed to extend through the interior of the plenum to reach the outlet pipe of the plenum and is configured to flow external cooling air through the plenum and cool the premixed gas in the plenum.

14. The low NOx premixed hydrogen burner according to claim 13, wherein: The outlet end of the inner cooling air supply pipe is formed to be on the same vertical line as the outlet end of the outlet pipe of the plenum chamber or to protrude from the outlet end of the outlet pipe of the plenum chamber.

15. The low NOx premixed hydrogen burner according to claim 13, wherein: An outlet end of the inner cooling air supply pipe is formed in a diffuser shape.

16. The low NOx premixed hydrogen burner according to claim 13, wherein: The outlet end of the inner cooling air supply pipe is formed to protrude from the outlet end of the plenum outlet pipe by a length of one third or less of a length of a flame formed from the outlet end of the inner cooling air supply pipe.

17. The low NOx premixed hydrogen burner according to claim 13, wherein: The flow rate and pressure of the inner cooling air in the inner cooling air supply pipe are formed to be greater than the flow rate and pressure of the premixed gas of the hydrogen burner at full load.

18. The low NOx premixed hydrogen burner according to claim 13, wherein: The inner cooling air supply duct includes a single inlet and a plurality of outlets.

19. A low NOx premixed hydrogen burner comprising: a plenum chamber including an inlet pipe and an outlet pipe, configured to mix hydrogen gas introduced through the inlet pipe with combustion air to produce a premixed gas for flame formation, wherein the outer cooling air supply pipe is installed in a ring shape to surround the outer circumference of the outlet pipe of the plenum chamber, and Therein, an inner cooling air supply pipe is installed to extend through the interior of the plenum chamber to reach the outlet pipe of the plenum chamber.

20. The low NOx premixed hydrogen burner according to claim 19, wherein: The outlet end of the plenum outlet pipe protrudes beyond the outlet end of the external cooling air supply pipe, and The outlet end of the inner cooling air supply pipe is formed to be on the same vertical line as the outlet end of the outlet pipe of the plenum chamber or to protrude from the outlet end of the outlet pipe of the plenum chamber.

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