Natural gas co-firing ammonia burner

Abstract

A natural gas co-firing ammonia burner includes first and second gas intake pipes, and a swirl mechanism. The first gas intake pipe has an air flow channel, a natural gas flow channel, and a mixing flow channel downstream of the air flow channel and the natural gas flow channel and having a first spout. Air from the air flow channel and a natural gas from the natural gas flow channel are mixed in the mixing flow channel. The second gas intake pipe is disposed in the first gas intake pipe and has an ammonia and air flow channel that receives an ammonia and air premix and has a second spout. The first spout surrounds the second spout and is separated from the second spout by a predetermined distance. The swirl mechanism is disposed in the mixing flow channel, and swirls and premixes the air and the natural gas.

Description

BACKGROUNDField of Invention

[0001] The present disclosure relates to a combustion technology, and more particularly, to a natural gas co-firing ammonia burner.Description of Related Art

[0002] In order to reduce the impact of greenhouse gases on the world's climate, under the constraints of the United Nations Framework Convention on Climate Change (UNFCCC), countries around the world are actively reducing greenhouse gas emissions. Among measures to reduce carbon emissions from industrial combustion processes, fuel selection is the most critical part. Hydrogen energy combustion can provide the heat required for power generation and achieve the goal of completely zero carbon emissions, such that hydrogen has become a popular alternative fuel.

[0003] However, hydrogen has the shortcomings of low molecular weight and difficulty in liquefaction, such that the storage and transportation of hydrogen have become the main costs of the application of hydrogen energy. In order to overcome the problems caused by the difficulty in transporting and storing hydrogen, a more feasible way at present is to use liquid hydrogen carriers as mediums for hydrogen energy utilization.

[0004] The ammonia has a hydrogen content of 17.9 wt %, such that the ammonia is an ideal hydrogen carrier and is a type of hydrogen energy fuel. However, the ammonia's calorific value (18.6 MJ / kg), flammability limit (0.63˜1.4), and flame speed (0.07 m / s) are all smaller than those of the methane. Therefore, the ammonia is a relatively non-flammable and low exothermic fuel, such that the combustion flame is easily extinguished and the combustion is unstable, resulting in emission pollution of unburned ammonia. Ammonia molecules contain nitrogen atoms, such that after the combustion reaction of the ammonia, it is easy to produce NOx emissions, which violates air pollution emission standards and causes environmental pollution.SUMMARY

[0005] Therefore, one objective of the present disclosure is to provide a natural gas co-firing ammonia burner, which uses a configuration in which an ammonia jet is injected from the middle and a natural gas flame is burned externally. A swirl mechanism can enhance a premixing effect of natural gas and air and increase the stability of a natural gas flame outside a combustion zone, thereby effectively providing the ammonia jet with thermal energy for a cracking reaction. In addition, the swirl mechanism also can control a flame pattern of the natural gas co-firing ammonia.

[0006] Another objective of the present disclosure is to provide a natural gas co-firing ammonia burner, which can separate the ammonia jet and the natural gas flame by a distance, such that after the ammonia enters a combustion chamber, the thermal energy provided by the natural gas flame can promote cracking, and the ammonia can be fully cracked before contacting an oxidizing medium outside the combustion zone, thereby significantly reducing the generation chance of NOx.

[0007] Still another objective of the present disclosure is to provide a natural gas co-firing ammonia burner, which can enhance a combustion effect of the ammonia by preheating a jet of an ammonia and air premix, such that after the ammonia jet and the peripheral natural gas flame are co-fired, the generation chance of NOx can be reduced.

[0008] According to the aforementioned objectives, the present disclosure provides a natural gas co-firing ammonia burner. The natural gas co-firing ammonia burner includes a first gas intake pipe, a second gas intake pipe, and a swirl mechanism. The first gas intake pipe has an air flow channel, a natural gas flow channel, and a mixing flow channel. The mixing flow channel is located downstream of the air flow channel and the natural gas flow channel and has a first spout. An air flowing out from the air flow channel and a natural gas flowing out from the natural gas flow channel are mixed in the mixing flow channel. The second gas intake pipe is disposed in the first gas intake pipe and has an ammonia and air flow channel. The ammonia and air flow channel is configured to receive an ammonia and air premix. The ammonia and air flow channel has a second spout. The first spout surrounds the second spout and is separated from the second spout by a predetermined distance. The swirl mechanism is disposed in the mixing flow channel and is configured to swirl and premix the air and the natural gas.

[0009] According to one embodiment of the present disclosure, the swirl mechanism includes at least one premixing swirl sheet, and a number of the at least one premixing swirl sheet is ranging from 1 to 3.

[0010] According to one embodiment of the present disclosure, when the number of the at least one premixing swirl sheet is 2 or 3, there is a gap between the premixing swirl sheets.

[0011] According to one embodiment of the present disclosure, directions of two adjacent ones of the premixing swirl sheets are different.

[0012] According to one embodiment of the present disclosure, the swirl mechanism further includes a flame-holding swirl sheet located downstream of the at least one premixing swirl sheet and adjacent to the first spout.

[0013] According to one embodiment of the present disclosure, a swirl number of the flame-holding swirl sheet is ranging from 0.2 to 0.6.

[0014] According to one embodiment of the present disclosure, a temperature of the ammonia and air premix is equal to or greater than 450° C.

[0015] According to one embodiment of the present disclosure, the natural gas co-firing ammonia burner further includes a compartment pipe. The compartment pipe is disposed in the first gas intake pipe and is located outside the second gas intake pipe. The compartment pipe is provided with a thermal insulating material.

[0016] According to one embodiment of the present disclosure, the predetermined distance is ranging from 10 mm to 50 mm.

[0017] According to one embodiment of the present disclosure, an equivalent ratio of the ammonia and air premix is ranging from 1.2 to 2.0.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Aspects of the present disclosure are best understood from the following detailed description in conjunction with the accompanying figures. It is noted that in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, dimensions of the various features can be arbitrarily increased or reduced for clarity of discussion.

[0019] FIG. 1 is a schematic three-dimensional perspective diagram of a natural gas co-firing ammonia burner in accordance with one embodiment of the present disclosure.

[0020] FIG. 2 is a schematic cross-sectional view of a natural gas co-firing ammonia burner in accordance with one embodiment of the present disclosure.

[0021] FIG. 3 is a schematic diagram of an upper portion of a natural gas co-firing ammonia burner in accordance with one embodiment of the present disclosure.DETAILED DESCRIPTION

[0022] The embodiments of the present disclosure are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable concepts that can be implemented in various specific contents. The embodiments discussed and disclosed are for illustrative purposes only and are not intended to limit the scope of the present disclosure. All of the embodiments of the present disclosure disclose various different features, and these features may be implemented separately or in combination as desired.

[0023] In addition, the terms “first”, “second”, and the like, as used herein, are not intended to mean a sequence or order, and are merely used to distinguish elements or operations described in the same technical terms.

[0024] The spatial relationship between two elements described in the present disclosure applies not only to the orientation depicted in the drawings, but also to the orientations not represented by the drawings, such as the orientation of the inversion. Moreover, the terms “connected”, “electrically connected”, or the like between two components referred to in the present disclosure are not limited to the direct connection or electrical connection of the two components, and may also include indirect connection or electrical connection as required.

[0025] In view of that ammonia easily produces NOx emissions after the combustion reaction, the present disclosure considers the difficult burning and high NOx emission characteristics of an ammonia fuel, and constructs a burner that co-fires two fuels of natural gas and ammonia to reduce carbon emissions of industrial combustion apparatuses.

[0026] Referring to FIG. 1 to FIG. 3, FIG. 1 to FIG. 3 respectively illustrate a three-dimensional perspective diagram and a schematic cross-sectional view of a natural gas co-firing ammonia burner 100, and a schematic diagram of an upper portion of the natural gas co-firing ammonia burner 100 in accordance with one embodiment of the present disclosure. The natural gas co-firing ammonia burner 100 can be used in industrial furnaces, such as heating furnaces, sintering furnaces, and boilers to perform operations, such as heating, melting, sintering, and heat treatment on workpieces. The natural gas co-firing ammonia burner 100 may mainly include a first gas intake pipe 200, a second gas intake pipe 300, and a swirl mechanism 400.

[0027] The first gas intake pipe 200 is a gas intake pipe for an air G1 and a natural gas G2. The first gas intake pipe 200 has a double pipe structure. For example, the first gas intake pipe 200 may be a double circular pipe structure. The first gas intake pipe 200 may be a pipe of other shapes, and the present disclosure is not limited thereto. A material of the first gas intake pipe 200 may be metal. As shown in FIG. 2, the first gas intake pipe 200 has an air flow channel 210, a natural gas flow channel 220, and a mixing flow channel 230. The air flow channel 210 has a gas inlet 212 and a gas outlet 214. The air G1 can flow into the air flow channel 210 from the gas inlet 212 and flow out of the air flow channel 210 from the gas outlet 214.

[0028] For example, the natural gas flow channel 220 may be located inside the air flow channel 210 and surrounded by the air flow channel 210. The natural gas flow channel 220 has a gas inlet 222 and a gas outlet 224, in which the gas outlet 224 is adjacent to the gas outlet 214 of the air flow channel 210. A natural gas G2 can flow into the natural gas flow channel 220 from the gas inlet 222 and flow out of the natural gas flow channel 220 from the gas outlet 224.

[0029] The mixing flow channel 230 is located downstream of the air flow channel 210 and the natural gas flow channel 220, and is adjacent to and fluidly connected to the gas outlet 214 of the air flow channel 210 and the gas outlet 224 of the natural gas flow channel 220. The mixing flow channel 230 has a first spout 232. Therefore, the air G1 flowing out from the air flow channel 210 and the natural gas G2 flowing out from the natural gas flow channel 220 can flow into the mixing flow channel 230, and are mixed in the mixing flow channel 230 and then sprayed out of the mixing flow channel 230 from the first spout 232. In the present embodiment, the mixing of the air G1 and the natural gas G2 is designed with a low equivalence ratio, and the equivalence ratio is smaller than 1, such as 0.9. Therefore, the oxygen in the residual air G1 in the mixture of the air G1 and the natural gas G2 can be used for the combustion of ammonia cracked products downstream.

[0030] Referring to FIG. 1 and FIG. 2 simultaneously, the swirl mechanism 400 is disposed in the mixing flow channel 230 of the first gas intake pipe 200. The swirl mechanism 400 can swirl the air G1 and natural gas G2 entering the mixing flow channel 230, such that the air G1 and the natural gas G2 can be premixed more effectively. The swirl mechanism 400 may mainly include at least one premixing swirl sheet. For example, the swirl mechanism 400 may include premixing swirl sheets 410 and 420. Here, two premixing swirl sheets 410 and 420 are used as an example. However, the present disclosure is not limited thereto. The natural gas co-firing ammonia burner 100 of the present disclosure may include one or more swirl sheets for premixing the air G1 and the natural gas G2. For example, the natural gas co-firing ammonia burner 100 may include 1 to 3 swirl sheets for premixing the air G1 and the natural gas G2.

[0031] In the example that the swirl mechanism 400 includes plural premixing swirl sheets 410 and 420, there is a gap G between two adjacent premixing swirl sheets 410 and 420. The design of the gap G allows the mixed gas of the air G1 and the natural gas G2 to diffuse due to the decrease in pressure when the mixed gas enters the gap G from the previous premixing swirl sheet 410, and the mixed gas to collide when the mixed gas enters the next premixing swirl sheet 420 from the gap G due to the increase in pressure. Therefore, the mixing effect of the air G1 and the natural gas G2 can be increased.

[0032] The premixing swirl sheet 410 includes plural blades 412 spaced apart from each other. The premixing swirl sheet 420 similarly includes plural blades 422 spaced apart from each other. In some examples, as shown in FIG. 1, directions of the blades 412 and 422 respectively included in the two adjacent premixing swirl sheets 410 and 420 are different. For example, each of the blades 412 may have a concave arc surface 412a, and each of the blades 422 may have a concave arc surface 422a, in which the concave arc surfaces 412a and the concave arc surfaces 422a face opposite directions. Or, as shown in FIG. 1, the blades 412 and 422 deflect in different directions. For example, the blades 412 are deflected toward the upper right, and the blades 422 are deflected toward the lower right. The design of the blades 412 and 422 in different directions can increase a disturbance effect to further enhance the mixing effect of the air G1 and the natural gas G2.

[0033] The swirl mechanism 400 may optionally include a flame-retaining swirl sheet 430. As shown in FIG. 2, the flame-retaining swirl sheet 430 is disposed in the mixing flow channel 230 of the first gas intake pipe 200. The flame-retaining swirl sheet 430 is located downstream of the premixing swirl sheets 410 and 420 and adjacent to the first spout 232 of the mixing channel 230. The flame-retaining swirl sheet 430 is separated from the adjacent premixing swirl sheet 420 to enhance the premixing effect of the air G1 and the natural gas G2. The flame-retaining swirl sheet 430 includes plural blades 432 spaced apart from each other. A direction of the blades 432 of the flame-retaining swirl sheet 430 is different from the direction of the blades 422 of the adjacent premixing swirl sheet 420 to further enhance the premixing effect of the air G1 and the natural gas G2.

[0034] The flame-retaining swirl sheet 430 can further enhance the mixing of the natural gas G2 and the air G1, control a flame pattern of the natural gas G2, provide a flame-retaining effect, and assist the stable combustion of the ammonia. In some examples, a swirl number of the flame-retaining swirl sheet 430 is ranging from 0.2 to 0.6.

[0035] As shown in FIG. 2, the second gas intake pipe 300 is disposed in the first gas intake pipe 200. The second gas intake pipe 300 may be, for example, substantially parallel to the first gas intake pipe 200. For example, a central axis of the second gas intake pipe 300 may overlap with a central axis of the first gas intake pipe 200. The second gas intake pipe 300 may be a round pipe. The second gas intake pipe 300 may be a pipe in other shapes, and the present disclosure is not limited thereto. Similarly, a material of the second gas intake pipe 300 may be metal, for example.

[0036] The second gas intake pipe 300 is a gas intake pipe for an ammonia and air premix G3. The second gas intake pipe 300 has an ammonia and air flow channel 310 to receive the ammonia and air premix G3. As shown in FIG. 2 and FIG. 3, the ammonia and air flow channel 310 is located inside the natural gas flow channel 220 and is surrounded by the natural gas flow channel 220. The ammonia and air flow channel 310 has a gas inlet 312 and a second spout 314. The ammonia and air premix G3 can flow into the ammonia and air flow channel 310 from the gas inlet 312, and then be sprayed out of the ammonia and air flow channel 310 from the second spout 314. A flow rate of the ammonia and air premix G3 can be adjusted according to a power of the natural gas co-firing ammonia burner 100.

[0037] The second spout 314 is adjacent to the first spout 232, and the first spout 232 surrounds the second spout 314. The first spout 232 and the second spout 314 are separated by a predetermined distance D. In some examples, the predetermined distance D is ranging 10 mm to 50 mm. Under the predetermined distance D in this range, it can effectively provide a high-temperature covering environment for the ammonia and air premix G3 to promote a hydrogen ion differentiation reaction in the ammonia-rich jet while preventing the combustion flame of the natural gas G2 and the air G1 from contacting the ammonia and air premix G3 too quickly to generate NOx.

[0038] The ammonia has been premixed with the air before entering the ammonia and air flow channel 310 to form the ammonia and air premix G3, such that the cracking activation energy of the ammonia can be reduced before burning, which makes it easier for ammonia to undergo a combustion reaction. In the present embodiment, the ammonia and air premix G3 is designed with a high equivalence ratio. In some examples, the equivalent ratio of the ammonia and air premix G3 is ranging from 1.2 to 2.0. Under the equivalence ratio range of the ammonia and air premix G3, the hydrogen ion decomposition reaction of the ammonia can be promoted, and then the hydrogen ions react with the oxygen in the residual air G1 in the mixture of the natural gas G2 and the air G1 downstream, thereby effectively reducing the generation chance of fuel-based NOx.

[0039] In some examples, before entering the ammonia and air flow channel 310, the ammonia and air premix G3 is preheated, such that a temperature of the ammonia and air premix G3 is equal to or greater than 450° C. After the ammonia and air premix G3 is preheated, the cracking effect of the ammonia can be increased, and the ammonia jet can be promoted to directly carry out a combustion reaction in the form of a higher hydrogen ion concentration, which can effectively reduce the generation of NOx. In application, waste heat recovery can be combined to preheat the ammonia and air premix G3, thereby reducing fuel usage.

[0040] As shown in FIG. 2 and FIG. 3, the natural gas co-firing ammonia burner 100 may optionally include a compartment pipe 500. The compartment pipe 500 is disposed in the first gas intake pipe 200 and is located outside the second gas intake pipe 300. The compartment pipe 500 has an accommodating space 510, and the accommodating space 510 surrounds the ammonia and air flow channel 310. The accommodating space 510 of the compartment pipe 500 is filled with a thermal insulating material 520. The thermal insulating material 520 can reduce the dissipation of the heat energy of the ammonia and air premix G3 injected into the ammonia and air flow channel 310 and slow down the drop in the temperature of the ammonia and air premix G3.

[0041] In some examples, as shown in FIG. 1 and FIG. 2, the natural gas co-firing ammonia burner 100 has a third spout 110, in which the third spout 110 is located downstream of the first spout 232 and the second spout 314. The third spout 110 has a tapered design to prevent the combustion flame of the natural gas G2 from spreading outward. Therefore, the high-temperature environment formed when the natural gas G2 is burned can effectively cover the ammonia and air premix G3.

[0042] It can be seen from the above embodiments that the present disclosure uses a configuration in which the ammonia and air premix is injected from the middle of the natural gas co-firing ammonia burner, the natural gas flame is burned externally, and the jet of the ammonia and air premix is separated from the natural gas flame by a distance. After the ammonia enters the combustion chamber and before the ammonia contacts the oxidizing medium outside the combustion zone, the thermal energy provided by the natural gas flame can promote the cracking of the ammonia, which can effectively reduce the generation chance of NOx. In addition, the swirl mechanism can enhance the premixing effect of the natural gas and the air, increase the stability of the natural gas flame outside the combustion zone, effectively provide the ammonia with thermal energy for a cracking reaction, and control a flame pattern of the natural gas co-firing ammonia.

[0043] Although the present disclosure has been disclosed above with embodiments, it is not intended to limit the present disclosure. Any person having ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure should be defined by the scope of the appended claims.

Examples

Embodiment Construction

[0022]The embodiments of the present disclosure are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable concepts that can be implemented in various specific contents. The embodiments discussed and disclosed are for illustrative purposes only and are not intended to limit the scope of the present disclosure. All of the embodiments of the present disclosure disclose various different features, and these features may be implemented separately or in combination as desired.

[0023]In addition, the terms “first”, “second”, and the like, as used herein, are not intended to mean a sequence or order, and are merely used to distinguish elements or operations described in the same technical terms.

[0024]The spatial relationship between two elements described in the present disclosure applies not only to the orientation depicted in the drawings, but also to the orientations not represented by the drawings, such as the orientation of the inversion...

BACKGROUNDField of Invention

[0001] The present disclosure relates to a combustion technology, and more particularly, to a natural gas co-firing ammonia burner.Description of Related Art

[0002] In order to reduce the impact of greenhouse gases on the world's climate, under the constraints of the United Nations Framework Convention on Climate Change (UNFCCC), countries around the world are actively reducing greenhouse gas emissions. Among measures to reduce carbon emissions from industrial combustion processes, fuel selection is the most critical part. Hydrogen energy combustion can provide the heat required for power generation and achieve the goal of completely zero carbon emissions, such that hydrogen has become a popular alternative fuel.

[0003] However, hydrogen has the shortcomings of low molecular weight and difficulty in liquefaction, such that the storage and transportation of hydrogen have become the main costs of the application of hydrogen energy. In order to overcome the problems caused by the difficulty in transporting and storing hydrogen, a more feasible way at present is to use liquid hydrogen carriers as mediums for hydrogen energy utilization.

[0004] The ammonia has a hydrogen content of 17.9 wt %, such that the ammonia is an ideal hydrogen carrier and is a type of hydrogen energy fuel. However, the ammonia's calorific value (18.6 MJ / kg), flammability limit (0.63˜1.4), and flame speed (0.07 m / s) are all smaller than those of the methane. Therefore, the ammonia is a relatively non-flammable and low exothermic fuel, such that the combustion flame is easily extinguished and the combustion is unstable, resulting in emission pollution of unburned ammonia. Ammonia molecules contain nitrogen atoms, such that after the combustion reaction of the ammonia, it is easy to produce NOx emissions, which violates air pollution emission standards and causes environmental pollution.SUMMARY

[0005] Therefore, one objective of the present disclosure is to provide a natural gas co-firing ammonia burner, which uses a configuration in which an ammonia jet is injected from the middle and a natural gas flame is burned externally. A swirl mechanism can enhance a premixing effect of natural gas and air and increase the stability of a natural gas flame outside a combustion zone, thereby effectively providing the ammonia jet with thermal energy for a cracking reaction. In addition, the swirl mechanism also can control a flame pattern of the natural gas co-firing ammonia.

[0006] Another objective of the present disclosure is to provide a natural gas co-firing ammonia burner, which can separate the ammonia jet and the natural gas flame by a distance, such that after the ammonia enters a combustion chamber, the thermal energy provided by the natural gas flame can promote cracking, and the ammonia can be fully cracked before contacting an oxidizing medium outside the combustion zone, thereby significantly reducing the generation chance of NOx.

[0007] Still another objective of the present disclosure is to provide a natural gas co-firing ammonia burner, which can enhance a combustion effect of the ammonia by preheating a jet of an ammonia and air premix, such that after the ammonia jet and the peripheral natural gas flame are co-fired, the generation chance of NOx can be reduced.

[0008] According to the aforementioned objectives, the present disclosure provides a natural gas co-firing ammonia burner. The natural gas co-firing ammonia burner includes a first gas intake pipe, a second gas intake pipe, and a swirl mechanism. The first gas intake pipe has an air flow channel, a natural gas flow channel, and a mixing flow channel. The mixing flow channel is located downstream of the air flow channel and the natural gas flow channel and has a first spout. An air flowing out from the air flow channel and a natural gas flowing out from the natural gas flow channel are mixed in the mixing flow channel. The second gas intake pipe is disposed in the first gas intake pipe and has an ammonia and air flow channel. The ammonia and air flow channel is configured to receive an ammonia and air premix. The ammonia and air flow channel has a second spout. The first spout surrounds the second spout and is separated from the second spout by a predetermined distance. The swirl mechanism is disposed in the mixing flow channel and is configured to swirl and premix the air and the natural gas.

[0009] According to one embodiment of the present disclosure, the swirl mechanism includes at least one premixing swirl sheet, and a number of the at least one premixing swirl sheet is ranging from 1 to 3.

[0010] According to one embodiment of the present disclosure, when the number of the at least one premixing swirl sheet is 2 or 3, there is a gap between the premixing swirl sheets.

[0011] According to one embodiment of the present disclosure, directions of two adjacent ones of the premixing swirl sheets are different.

[0012] According to one embodiment of the present disclosure, the swirl mechanism further includes a flame-holding swirl sheet located downstream of the at least one premixing swirl sheet and adjacent to the first spout.

[0013] According to one embodiment of the present disclosure, a swirl number of the flame-holding swirl sheet is ranging from 0.2 to 0.6.

[0014] According to one embodiment of the present disclosure, a temperature of the ammonia and air premix is equal to or greater than 450° C.

[0015] According to one embodiment of the present disclosure, the natural gas co-firing ammonia burner further includes a compartment pipe. The compartment pipe is disposed in the first gas intake pipe and is located outside the second gas intake pipe. The compartment pipe is provided with a thermal insulating material.

[0016] According to one embodiment of the present disclosure, the predetermined distance is ranging from 10 mm to 50 mm.

[0017] According to one embodiment of the present disclosure, an equivalent ratio of the ammonia and air premix is ranging from 1.2 to 2.0.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Aspects of the present disclosure are best understood from the following detailed description in conjunction with the accompanying figures. It is noted that in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, dimensions of the various features can be arbitrarily increased or reduced for clarity of discussion.

[0019] FIG. 1 is a schematic three-dimensional perspective diagram of a natural gas co-firing ammonia burner in accordance with one embodiment of the present disclosure.

[0020] FIG. 2 is a schematic cross-sectional view of a natural gas co-firing ammonia burner in accordance with one embodiment of the present disclosure.

[0021] FIG. 3 is a schematic diagram of an upper portion of a natural gas co-firing ammonia burner in accordance with one embodiment of the present disclosure.DETAILED DESCRIPTION

[0022] The embodiments of the present disclosure are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable concepts that can be implemented in various specific contents. The embodiments discussed and disclosed are for illustrative purposes only and are not intended to limit the scope of the present disclosure. All of the embodiments of the present disclosure disclose various different features, and these features may be implemented separately or in combination as desired.

[0023] In addition, the terms “first”, “second”, and the like, as used herein, are not intended to mean a sequence or order, and are merely used to distinguish elements or operations described in the same technical terms.

[0024] The spatial relationship between two elements described in the present disclosure applies not only to the orientation depicted in the drawings, but also to the orientations not represented by the drawings, such as the orientation of the inversion. Moreover, the terms “connected”, “electrically connected”, or the like between two components referred to in the present disclosure are not limited to the direct connection or electrical connection of the two components, and may also include indirect connection or electrical connection as required.

[0025] In view of that ammonia easily produces NOx emissions after the combustion reaction, the present disclosure considers the difficult burning and high NOx emission characteristics of an ammonia fuel, and constructs a burner that co-fires two fuels of natural gas and ammonia to reduce carbon emissions of industrial combustion apparatuses.

[0026] Referring to FIG. 1 to FIG. 3, FIG. 1 to FIG. 3 respectively illustrate a three-dimensional perspective diagram and a schematic cross-sectional view of a natural gas co-firing ammonia burner 100, and a schematic diagram of an upper portion of the natural gas co-firing ammonia burner 100 in accordance with one embodiment of the present disclosure. The natural gas co-firing ammonia burner 100 can be used in industrial furnaces, such as heating furnaces, sintering furnaces, and boilers to perform operations, such as heating, melting, sintering, and heat treatment on workpieces. The natural gas co-firing ammonia burner 100 may mainly include a first gas intake pipe 200, a second gas intake pipe 300, and a swirl mechanism 400.

[0027] The first gas intake pipe 200 is a gas intake pipe for an air G1 and a natural gas G2. The first gas intake pipe 200 has a double pipe structure. For example, the first gas intake pipe 200 may be a double circular pipe structure. The first gas intake pipe 200 may be a pipe of other shapes, and the present disclosure is not limited thereto. A material of the first gas intake pipe 200 may be metal. As shown in FIG. 2, the first gas intake pipe 200 has an air flow channel 210, a natural gas flow channel 220, and a mixing flow channel 230. The air flow channel 210 has a gas inlet 212 and a gas outlet 214. The air G1 can flow into the air flow channel 210 from the gas inlet 212 and flow out of the air flow channel 210 from the gas outlet 214.

[0028] For example, the natural gas flow channel 220 may be located inside the air flow channel 210 and surrounded by the air flow channel 210. The natural gas flow channel 220 has a gas inlet 222 and a gas outlet 224, in which the gas outlet 224 is adjacent to the gas outlet 214 of the air flow channel 210. A natural gas G2 can flow into the natural gas flow channel 220 from the gas inlet 222 and flow out of the natural gas flow channel 220 from the gas outlet 224.

[0029] The mixing flow channel 230 is located downstream of the air flow channel 210 and the natural gas flow channel 220, and is adjacent to and fluidly connected to the gas outlet 214 of the air flow channel 210 and the gas outlet 224 of the natural gas flow channel 220. The mixing flow channel 230 has a first spout 232. Therefore, the air G1 flowing out from the air flow channel 210 and the natural gas G2 flowing out from the natural gas flow channel 220 can flow into the mixing flow channel 230, and are mixed in the mixing flow channel 230 and then sprayed out of the mixing flow channel 230 from the first spout 232. In the present embodiment, the mixing of the air G1 and the natural gas G2 is designed with a low equivalence ratio, and the equivalence ratio is smaller than 1, such as 0.9. Therefore, the oxygen in the residual air G1 in the mixture of the air G1 and the natural gas G2 can be used for the combustion of ammonia cracked products downstream.

[0030] Referring to FIG. 1 and FIG. 2 simultaneously, the swirl mechanism 400 is disposed in the mixing flow channel 230 of the first gas intake pipe 200. The swirl mechanism 400 can swirl the air G1 and natural gas G2 entering the mixing flow channel 230, such that the air G1 and the natural gas G2 can be premixed more effectively. The swirl mechanism 400 may mainly include at least one premixing swirl sheet. For example, the swirl mechanism 400 may include premixing swirl sheets 410 and 420. Here, two premixing swirl sheets 410 and 420 are used as an example. However, the present disclosure is not limited thereto. The natural gas co-firing ammonia burner 100 of the present disclosure may include one or more swirl sheets for premixing the air G1 and the natural gas G2. For example, the natural gas co-firing ammonia burner 100 may include 1 to 3 swirl sheets for premixing the air G1 and the natural gas G2.

[0031] In the example that the swirl mechanism 400 includes plural premixing swirl sheets 410 and 420, there is a gap G between two adjacent premixing swirl sheets 410 and 420. The design of the gap G allows the mixed gas of the air G1 and the natural gas G2 to diffuse due to the decrease in pressure when the mixed gas enters the gap G from the previous premixing swirl sheet 410, and the mixed gas to collide when the mixed gas enters the next premixing swirl sheet 420 from the gap G due to the increase in pressure. Therefore, the mixing effect of the air G1 and the natural gas G2 can be increased.

[0032] The premixing swirl sheet 410 includes plural blades 412 spaced apart from each other. The premixing swirl sheet 420 similarly includes plural blades 422 spaced apart from each other. In some examples, as shown in FIG. 1, directions of the blades 412 and 422 respectively included in the two adjacent premixing swirl sheets 410 and 420 are different. For example, each of the blades 412 may have a concave arc surface 412a, and each of the blades 422 may have a concave arc surface 422a, in which the concave arc surfaces 412a and the concave arc surfaces 422a face opposite directions. Or, as shown in FIG. 1, the blades 412 and 422 deflect in different directions. For example, the blades 412 are deflected toward the upper right, and the blades 422 are deflected toward the lower right. The design of the blades 412 and 422 in different directions can increase a disturbance effect to further enhance the mixing effect of the air G1 and the natural gas G2.

[0033] The swirl mechanism 400 may optionally include a flame-retaining swirl sheet 430. As shown in FIG. 2, the flame-retaining swirl sheet 430 is disposed in the mixing flow channel 230 of the first gas intake pipe 200. The flame-retaining swirl sheet 430 is located downstream of the premixing swirl sheets 410 and 420 and adjacent to the first spout 232 of the mixing channel 230. The flame-retaining swirl sheet 430 is separated from the adjacent premixing swirl sheet 420 to enhance the premixing effect of the air G1 and the natural gas G2. The flame-retaining swirl sheet 430 includes plural blades 432 spaced apart from each other. A direction of the blades 432 of the flame-retaining swirl sheet 430 is different from the direction of the blades 422 of the adjacent premixing swirl sheet 420 to further enhance the premixing effect of the air G1 and the natural gas G2.

[0034] The flame-retaining swirl sheet 430 can further enhance the mixing of the natural gas G2 and the air G1, control a flame pattern of the natural gas G2, provide a flame-retaining effect, and assist the stable combustion of the ammonia. In some examples, a swirl number of the flame-retaining swirl sheet 430 is ranging from 0.2 to 0.6.

[0035] As shown in FIG. 2, the second gas intake pipe 300 is disposed in the first gas intake pipe 200. The second gas intake pipe 300 may be, for example, substantially parallel to the first gas intake pipe 200. For example, a central axis of the second gas intake pipe 300 may overlap with a central axis of the first gas intake pipe 200. The second gas intake pipe 300 may be a round pipe. The second gas intake pipe 300 may be a pipe in other shapes, and the present disclosure is not limited thereto. Similarly, a material of the second gas intake pipe 300 may be metal, for example.

[0036] The second gas intake pipe 300 is a gas intake pipe for an ammonia and air premix G3. The second gas intake pipe 300 has an ammonia and air flow channel 310 to receive the ammonia and air premix G3. As shown in FIG. 2 and FIG. 3, the ammonia and air flow channel 310 is located inside the natural gas flow channel 220 and is surrounded by the natural gas flow channel 220. The ammonia and air flow channel 310 has a gas inlet 312 and a second spout 314. The ammonia and air premix G3 can flow into the ammonia and air flow channel 310 from the gas inlet 312, and then be sprayed out of the ammonia and air flow channel 310 from the second spout 314. A flow rate of the ammonia and air premix G3 can be adjusted according to a power of the natural gas co-firing ammonia burner 100.

[0037] The second spout 314 is adjacent to the first spout 232, and the first spout 232 surrounds the second spout 314. The first spout 232 and the second spout 314 are separated by a predetermined distance D. In some examples, the predetermined distance D is ranging 10 mm to 50 mm. Under the predetermined distance D in this range, it can effectively provide a high-temperature covering environment for the ammonia and air premix G3 to promote a hydrogen ion differentiation reaction in the ammonia-rich jet while preventing the combustion flame of the natural gas G2 and the air G1 from contacting the ammonia and air premix G3 too quickly to generate NOx.

[0038] The ammonia has been premixed with the air before entering the ammonia and air flow channel 310 to form the ammonia and air premix G3, such that the cracking activation energy of the ammonia can be reduced before burning, which makes it easier for ammonia to undergo a combustion reaction. In the present embodiment, the ammonia and air premix G3 is designed with a high equivalence ratio. In some examples, the equivalent ratio of the ammonia and air premix G3 is ranging from 1.2 to 2.0. Under the equivalence ratio range of the ammonia and air premix G3, the hydrogen ion decomposition reaction of the ammonia can be promoted, and then the hydrogen ions react with the oxygen in the residual air G1 in the mixture of the natural gas G2 and the air G1 downstream, thereby effectively reducing the generation chance of fuel-based NOx.

[0039] In some examples, before entering the ammonia and air flow channel 310, the ammonia and air premix G3 is preheated, such that a temperature of the ammonia and air premix G3 is equal to or greater than 450° C. After the ammonia and air premix G3 is preheated, the cracking effect of the ammonia can be increased, and the ammonia jet can be promoted to directly carry out a combustion reaction in the form of a higher hydrogen ion concentration, which can effectively reduce the generation of NOx. In application, waste heat recovery can be combined to preheat the ammonia and air premix G3, thereby reducing fuel usage.

[0040] As shown in FIG. 2 and FIG. 3, the natural gas co-firing ammonia burner 100 may optionally include a compartment pipe 500. The compartment pipe 500 is disposed in the first gas intake pipe 200 and is located outside the second gas intake pipe 300. The compartment pipe 500 has an accommodating space 510, and the accommodating space 510 surrounds the ammonia and air flow channel 310. The accommodating space 510 of the compartment pipe 500 is filled with a thermal insulating material 520. The thermal insulating material 520 can reduce the dissipation of the heat energy of the ammonia and air premix G3 injected into the ammonia and air flow channel 310 and slow down the drop in the temperature of the ammonia and air premix G3.

[0041] In some examples, as shown in FIG. 1 and FIG. 2, the natural gas co-firing ammonia burner 100 has a third spout 110, in which the third spout 110 is located downstream of the first spout 232 and the second spout 314. The third spout 110 has a tapered design to prevent the combustion flame of the natural gas G2 from spreading outward. Therefore, the high-temperature environment formed when the natural gas G2 is burned can effectively cover the ammonia and air premix G3.

[0042] It can be seen from the above embodiments that the present disclosure uses a configuration in which the ammonia and air premix is injected from the middle of the natural gas co-firing ammonia burner, the natural gas flame is burned externally, and the jet of the ammonia and air premix is separated from the natural gas flame by a distance. After the ammonia enters the combustion chamber and before the ammonia contacts the oxidizing medium outside the combustion zone, the thermal energy provided by the natural gas flame can promote the cracking of the ammonia, which can effectively reduce the generation chance of NOx. In addition, the swirl mechanism can enhance the premixing effect of the natural gas and the air, increase the stability of the natural gas flame outside the combustion zone, effectively provide the ammonia with thermal energy for a cracking reaction, and control a flame pattern of the natural gas co-firing ammonia.

[0043] Although the present disclosure has been disclosed above with embodiments, it is not intended to limit the present disclosure. Any person having ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure should be defined by the scope of the appended claims.

Examples

Embodiment Construction

[0022]The embodiments of the present disclosure are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable concepts that can be implemented in various specific contents. The embodiments discussed and disclosed are for illustrative purposes only and are not intended to limit the scope of the present disclosure. All of the embodiments of the present disclosure disclose various different features, and these features may be implemented separately or in combination as desired.

[0023]In addition, the terms “first”, “second”, and the like, as used herein, are not intended to mean a sequence or order, and are merely used to distinguish elements or operations described in the same technical terms.

[0024]The spatial relationship between two elements described in the present disclosure applies not only to the orientation depicted in the drawings, but also to the orientations not represented by the drawings, such as the orientation of the inversion...

Claims

1. A natural gas co-firing ammonia burner, comprising:a first gas intake pipe having an air flow channel, a natural gas flow channel, and a mixing flow channel, wherein the mixing flow channel is located downstream of the air flow channel and the natural gas flow channel and has a first spout, and an air flowing out from the air flow channel and a natural gas flowing out from the natural gas flow channel are mixed in the mixing flow channel;a second gas intake pipe disposed in the first gas intake pipe and having an ammonia and air flow channel, wherein the ammonia and air flow channel is configured to receive an ammonia and air premix, the ammonia and air flow channel has a second spout, and the first spout surrounds the second spout and is separated from the second spout by a predetermined distance; anda swirl mechanism disposed in the mixing flow channel and configured to swirl and premix the air and the natural gas.

2. The natural gas co-firing ammonia burner of claim 1, wherein the swirl mechanism comprises at least one premixing swirl sheet, and a number of the at least one premixing swirl sheet is ranging from 1 to 3.

3. The natural gas co-firing ammonia burner of claim 2, wherein when the number of the at least one premixing swirl sheet is 2 or 3, there is a gap between the premixing swirl sheets.

4. The natural gas co-firing ammonia burner of claim 3, wherein directions of two adjacent ones of the premixing swirl sheets are different.

5. The natural gas co-firing ammonia burner of claim 2, wherein the swirl mechanism further comprises a flame-retaining swirl sheet located downstream of the at least one premixing swirl sheet and adjacent to the first spout.

6. The natural gas co-firing ammonia burner of claim 5, wherein a swirl number of the flame-retaining swirl sheet is ranging from 0.2 to 0.6.

7. The natural gas co-firing ammonia burner of claim 1, wherein a temperature of the ammonia and air premix is equal to or greater than 450° C.

8. The natural gas co-firing ammonia burner of claim 1, further comprising a compartment pipe, wherein the compartment pipe is disposed in the first gas intake pipe and is located outside the second gas intake pipe, and the compartment pipe is provided with a thermal insulating material.

9. The natural gas co-firing ammonia burner of claim 1, wherein the predetermined distance is ranging from 10 mm to 50 mm.

10. The natural gas co-firing ammonia burner of claim 1, wherein an equivalent ratio of the ammonia and air premix is ranging from 1.2 to 2.0.

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