Burner

Abstract

A burner according to an embodiment of the present invention may comprise an ignition nozzle, a first fuel nozzle configured to eject first fuel, a first air nozzle configured to eject first air, and a second fuel nozzle configured to eject second fuel. The first air nozzle may be disposed between the first fuel nozzle and the second fuel nozzle, and the first fuel may include ammonia.

Description

burner

[0001] The present invention relates to a burner.

[0002] A rotary kiln is equipment designed to produce processed raw materials according to the purpose of each process by slowly moving and heating raw materials within a long cylindrical rotating furnace lined with refractory material.

[0003] Rotary kilns can be classified according to the heating method into indirect heating types (external heating types), which heat the walls using an external heat source, and direct heating types (internal heating types), which place the heat source inside the rotary kiln.

[0004] The rotary kiln burner is a device inserted into the interior of the furnace at one end of this direct-heating rotary kiln to supply heat to the raw material particle layer through the combustion of fuel.

[0005] In rotary kilns, appropriate requirements exist regarding flame characteristics, temperature distribution, and the emission of environmental pollutants in combustion flue gases due to constraints imposed by the narrow and elongated shape of the furnace and the characteristics of the input fuel and raw materials; therefore, the burner structure and operational control are crucial for meeting these requirements.

[0006] Meanwhile, due to intensified global warming, countries and major companies around the world are pursuing ESG (environmental, social, and governance) policies, and decarbonization policies are being intensively researched.

[0007] In addition, nitrogen oxides (NOx), a reactant involved in the formation of ultrafine dust, are subject to strict regulations as an environmentally controlled substance.

[0008] Currently, carbon-based fossil fuels such as LNG, LPG, process byproduct gas, oil, and coal are typically used as fuels in rotary kiln burners. Recently, a new approach has emerged to fundamentally and directly reduce carbon emissions during combustion by replacing existing carbon-based fuels with carbon-free combustible materials, or carbon-free fuels.

[0009] In this context, ammonia has recently been prominently discussed as a representative carbon-free fuel. Interest in ammonia began as a promising intermediate medium for the economical and stable domestic transport of hydrogen produced overseas; once transported domestically, this ammonia undergoes a reforming process to be converted back into hydrogen, which can then be applied to various hydrogen utilization sites.

[0010] As there are almost no demonstration cases of ammonia being used as fuel in large-scale industrial facilities, including rotary kilns, there is a lack of review regarding appropriate application methods for existing facilities.

[0011] In addition, compared to traditional fossil fuels, ammonia requires a high energy for ignition and has a significantly lower theoretical flame propagation speed, resulting in poor combustibility; furthermore, the nitrogen components contained in the fuel can lead to increased NOx emissions in the combustion flue gas.

[0012] In addition, regarding the basic types of burners according to conventional technology, such as conventional industrial burners, the design is based on a nozzle mix method or a partial premix method in which a mixing section is configured to mix fuel and primary air inside the burner to form a central flame in order to promote stable combustion.

[0013] On the other hand, rotary kilns generally aim to form a long flame and achieve mixing through the high-speed injection of air and fuel in a diffusion flame burner structure that lacks an internal mixing section. Therefore, in implementing the fundamental principles for stable combustion and nitrogen oxide reduction, such as the aforementioned multi-stage combustion, it is necessary to modify the methods and standards.

[0014] In rotary kilns, in many cases, only a portion equivalent to 10 to 20 percent of the total air required for combustion is supplied directly through the burner, while most of the remaining combustion air is supplied through the outside of the burner or through the burner's outer channels.

[0015] Here, the nozzle injection velocity of combustion air and fuel gas introduced through the burner is very fast, at approximately 100 m / s, which exceeds the conditions of a typical industrial burner, whereas the air velocity outside the burner passing through the cylindrical rotary furnace is very slow, at least several m / s.

[0016] Depending on the aforementioned flow velocity conditions, the flow phenomenon caused by the momentum difference between the high-speed flow injected from the burner and the surrounding low-speed flow in a closed space within a rotary furnace with a diameter of several meters can significantly affect the mixing of fuel and air and the tendency of flame formation.

[0017] Therefore, there is a need for a rotary kiln burner that can maintain the basic characteristics of the burner and flame even when ammonia is co-fired, while ensuring a stable combustion state and achieving a reduction in emissions within the combustion gas.

[0018] The present invention aims to solve the above problems by providing a burner capable of reducing the generation of nitrogen oxides and stably burning fuel.

[0019] The objectives of the present invention are not limited to those mentioned above, and other unmentioned objectives will be clearly understood by those skilled in the art from the description below.

[0020] The present invention provides a burner formed as follows to achieve the above objectives.

[0021] According to one embodiment of the present invention, the burner comprises an ignition nozzle, a first fuel nozzle for injecting a first fuel, a first air nozzle for injecting a first air, and a second fuel nozzle for injecting a second fuel, wherein the first air nozzle is disposed between the first fuel nozzle and the second fuel nozzle, and the first fuel may include ammonia.

[0022] According to one embodiment of the present invention, the first fuel nozzle may be positioned between the ignition nozzle and the first air nozzle.

[0023] According to one embodiment of the present invention, a second air nozzle disposed outside the second fuel nozzle and injecting second air may be further included.

[0024] According to one embodiment of the present invention, the first fuel may include ammonia.

[0025] According to one embodiment of the present invention, the injection ports of the first fuel nozzle, the first air nozzle, and the second fuel nozzle may each be arranged to have a symmetrical structure.

[0026] According to one embodiment of the present invention, the injection ports of the first fuel nozzle, the first air nozzle, and the second fuel nozzle may each be arranged to form a virtual circle.

[0027] Each of the circles formed by the injection ports of the first fuel nozzle, the first air nozzle, and the second fuel nozzle has the same center and may have different radii.

[0028] According to one embodiment of the present invention, a preheating device for preheating air is provided, and a third air nozzle for supplying preheated third air is further provided, wherein the third air may be supplied at a slower speed than the first air and the second air.

[0029] According to one embodiment of the present invention, the first air nozzle may further include a swirling portion capable of swirling the first air being sprayed.

[0030] According to one embodiment of the present invention, the burner can use fuel containing ammonia while minimizing the generation of nitrogen oxides (NOx) and burning it stably.

[0031] The effects of the present invention are not limited to those described above, and other unmentioned effects will be clearly recognized by a person skilled in the art from the description below.

[0032] FIG. 1 is a cross-sectional view of a burner according to one embodiment of the present invention.

[0033] FIG. 2 is a front view of a burner according to one embodiment of the present invention.

[0034] Figure 3 is an enlarged view of part A of Figure 1.

[0035] FIG. 4 is a drawing that exemplarily shows the shape of a flame according to a first comparative embodiment.

[0036] FIG. 5 is a drawing that exemplarily shows the shape of a flame according to a second comparative embodiment.

[0037] FIG. 6 is a drawing that exemplarily shows the shape of a flame according to one embodiment of the present invention.

[0038] Figure 7 is a graph exemplarily showing the amount of nitrogen oxides generated according to the co-firing rate based on the ammonia injection method.

[0039] Specific embodiments of the present invention will be described below with reference to the attached drawings. However, the concept of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the concept of the present invention may easily propose other inventions that are inferior or other embodiments included within the scope of the concept of the present invention by adding, changing, or deleting other components within the same scope of the concept, and such are also to be considered to be included within the scope of the concept of the present invention.

[0040] Additionally, components with the same function within the scope of the same concept appearing in the drawings of each embodiment are described using the same reference numeral.

[0041] FIG. 1 is a cross-sectional view of a burner (1) according to one embodiment of the present invention, FIG. 2 is a front view of a burner (1) according to one embodiment of the present invention, and FIG. 3 is an enlarged view of part A of FIG. 1.

[0042] Referring to FIGS. 1 to 3, a burner (1) according to one embodiment of the present invention may include an ignition nozzle (100), a first air nozzle (200), a second air nozzle (400), a first fuel nozzle (300), and a second fuel nozzle (500).

[0043]

[0044] A burner (1) according to one embodiment of the present invention can improve the combustibility of ammonia fuel and reduce the generation of nitrogen oxides by injecting a first fuel containing ammonia and a second fuel containing carbon, such as a conventional fuel using natural gas, through separate individual nozzles to burn them.

[0045] The burner (1) has a circular cross-section overall and can be provided in a cylindrical shape that extends in the longitudinal direction.

[0046] An ignition nozzle (100) may be placed in the center of the burner (1).

[0047] The ignition nozzle (100) can ignite the burner (1) using an ignition spark (110) provided on the inside.

[0048] For example, an ignition spark (110) is positioned at the end of an ignition nozzle (200), and electricity is supplied to the ignition spark (110) using an ignition line (120) that extends along the ignition nozzle (200) to generate a spark and ignite the burner (1).

[0049] The ignition nozzle (100) may be configured to ignite the fuel supplied to the burner (1), and may safely and stably maintain a pilot flame before the burner (1) operates.

[0050] The first fuel nozzle (300) can be configured so that the first fuel is injected through the first fuel injection port (320) after being drawn in through the first fuel supply port (310).

[0051] The first fuel injection port (320) can be positioned to surround the ignition nozzle (100).

[0052] Referring to FIG. 2(a), the first fuel injection port (320) may be spaced apart at a predetermined distance along the outer surface of the ignition nozzle (100) so that the first fuel can be injected.

[0053] The first fuel nozzle (300) may have a hollow pipe structure, and at least one first fuel injection port (320) may be positioned outside the ignition nozzle (100) to inject the first fuel.

[0054] The first fuel injection port (320) can be provided to have a symmetrical structure.

[0055] Referring to FIG. 2(b), for example, the first fuel injection port (320) may be provided in a donut shape that surrounds the ignition nozzle (100).

[0056] Alternatively, for example, referring to FIG. 2(a), a plurality of first fuel injection ports (320) may be provided so as to be symmetrically arranged around the ignition nozzle (100).

[0057] More specifically, the first fuel injection port (320) may be composed of a plurality of pipes, and the plurality of pipes may be arranged on a virtual circumferential surface centered on the axis of the burner (1) and each may be arranged with equal spacing.

[0058] If the first fuel injection port (320) has an asymmetric structure, it may be difficult to control the flame due to the asymmetry of the first fuel being injected.

[0059] The first air nozzle (200) can be positioned along the outer side of the first fuel, and the first air can be drawn in through the first air supply port (210) and then injected through the first air injection port (220).

[0060] Here, the first air allows combustion to be maintained in the burner (1) and can play an important role in the characteristics of the flame.

[0061] The first air nozzle (220) may further include a swivel section.

[0062] The swirling section may be a guide vane or swirler structure, and the swirling section may cause the first air injected through the first air nozzle (220) to form a swirling flow. Through this, it may help to mix the first air and the first fuel well.

[0063] Additionally, the first air nozzle (220) may have a structure that can adjust the spray angle of the nozzle and, as needed, generate a swirling flow or eliminate the swirling flow.

[0064] The second fuel nozzle (500) can be positioned outside the first air nozzle (200), and the second fuel can be drawn in through the second fuel supply port (510) and then injected through the second fuel injection port (520).

[0065] The second air nozzle (400) can be positioned on the outside of the second fuel nozzle (500).

[0066] Alternatively, the second air nozzle (400) may be positioned at approximately the same location as the second fuel nozzle (500). For example, the second air nozzle (400) and the second fuel nozzle (500) may be positioned intersectingly on a virtual circle centered on the axis of the burner (1).

[0067] After the second air is drawn in through the second air supply port (410), it can be injected through the second air injection port (420).

[0068] In a burner (1) according to one embodiment of the present invention, the main flame can be combusted by the second fuel injected from the second fuel nozzle (500) and the second air injected from the second air nozzle (400), so that low-speed air outside the burner (1) is drawn toward the main flame side and mixed together.

[0069] A burner (1) according to one embodiment of the present invention may have an ignition nozzle (100), a first air injection port (220), a second air injection port (420), a first fuel injection port (320), and a second fuel injection port (520) arranged in a symmetrical structure.

[0070] In other words, in a burner (1) according to one embodiment of the present invention, a first air, a second air, a first fuel, and a second fuel can be symmetrically injected around an ignition nozzle (100).

[0071] More specifically, the first fuel injection port (320) may be provided in a donut shape centered on the ignition nozzle (100), or may be provided as a plurality of holes arranged at equal intervals on a virtual circumferential surface centered on the ignition nozzle (100).

[0072] The first air nozzle (220) may be provided in a donut shape centered on the ignition nozzle (100), or may be provided as a plurality of holes arranged at equal intervals on a virtual circumferential surface centered on the ignition nozzle (100).

[0073] Here, the radius of the virtual circumferential surface formed by the first air nozzle (220) may be larger than the radius of the virtual circumferential surface formed by the first fuel nozzle (320), and the first fuel nozzle (320) may be positioned between the first air nozzle (220) and the ignition nozzle (100).

[0074] Here, by positioning the first combustion nozzle inside the first air nozzle (220) and injecting, a first fuel containing at least ammonia is mixed with primary air inside the flame region to form a locally fuel-rich condition and induce a core region to react first at a location close to the burner (1).

[0075] Through this, a flame can be stably generated by igniting a first fuel containing flame-retardant ammonia near the point where the flame starts.

[0076] In addition, by reducing excessive mixing of air and ammonia to suppress the fuel-NOx generation reaction, the final amount of nitrogen oxides can be reduced.

[0077] A burner (1) according to one embodiment of the present invention may be placed on one side of a furnace (2) that includes a combustion space (CC) in which a flame is generated and maintained.

[0078] Here, the furnace (2) may have a cylindrical shape and may be a rotary kiln. Additionally, the combustion space (CC) may be a space where at least one of the first fuel and the second fuel undergoes a combustion reaction with air.

[0079] A burner (1) according to one embodiment of the present invention may further include a third air nozzle (600) including a preheating device, and preheated air may be introduced through a third air supply port (610) and injected through a third air injection port (620).

[0080] The third air nozzle (600) can preheat the air using a preheating device and supply the preheated air to the combustion space (CC).

[0081] For example, the third air nozzle (600) can preheat air corresponding to 80-90% of the amount of air required for combustion and supply it to the combustion space (CC), and the first air nozzle (200) and the second air nozzle (400) can supply 10-20% of the air required for combustion at room temperature.

[0082] Here, the distribution ratio of air supplied through the first air nozzle (200) and the second air nozzle (400) can be set differently depending on the type of fuel, combustion load, and flame condition.

[0083] Meanwhile, a burner (1) that does not have a third air nozzle (600) including a preheating device can supply air necessary for combustion using a first air nozzle (200) and a second air nozzle (400).

[0084] Here, the first air nozzle (200) can supply approximately 10% of the air required for combustion, and the remaining air required for combustion can be supplied using the second air nozzle (400).

[0085] Here, the distribution ratio of air supplied through the first air nozzle (200) and the second air nozzle (400) can be set differently depending on the arrangement structure of the first air nozzle (200) and the second air nozzle (400), the type of fuel, the combustion load, and the flame state.

[0086] FIG. 4 is a drawing exemplarily showing the shape of a flame according to a first comparative embodiment, FIG. 5 is a drawing exemplarily showing the shape of a flame according to a second comparative embodiment, and FIG. 6 is a drawing exemplarily showing the shape of a flame according to an embodiment of the present invention.

[0087] FIGS. 4 and 5 are schematic diagrams showing the flame structure of a burner (1) and the distribution of chemical species within the flame region according to the supply method of the first fuel and the second fuel.

[0088] FIG. 4 may exemplarily show the flame structure and the distribution of chemical species within the flame region in the first comparative embodiment, and the first comparative embodiment may be an embodiment in which only the second fuel is supplied using the second fuel nozzle (500) without using the first fuel containing ammonia.

[0089] For example, the first comparative embodiment may be an embodiment in which only the second fuel, such as natural gas, which is the main fuel, is supplied from the second fuel nozzle (500).

[0090] In the first comparative embodiment, a second fuel is injected from a second fuel nozzle (500), and primary air and secondary air can be injected into and outside the injected second fuel. A third air of low speed is introduced from outside the burner (1) so that the mixing of fuel and air and the combustion reaction can proceed.

[0091] In the first comparative example, the flame structure can form a first radical region (RZ1).

[0092] Here, the first radical region (RZ1) can form a high-temperature flame region that can typically be represented by an OH radical region.

[0093] Here, nitrogen oxides, represented by NO generated during combustion, can mostly be concentrated in regions where these OH radicals are strongly formed.

[0094] FIG. 5 illustrates, in a second comparative example, the flame structure and the distribution of chemical species within the flame region, and the second comparative example may be an example in which the first fuel is mixed with the second fuel and supplied using a second fuel nozzle (500).

[0095] Referring to FIG. 5, in the second comparative embodiment, in addition to the first radical region (RZ1), a second radical region (RZ2) may be formed near the point where the flame starts.

[0096] Here, the second radical region (RZ2) may be a region where NH2 and NH radical reactions actively occur.

[0097] In the second radical zone (RZ2), the first fuel reacts rapidly with the second fuel and air within the main flame zone, which can lead to an increase in nitrogen oxide emissions.

[0098] In particular, when the mixing ratio of the first fuel increases, the injection flow rate increases as the volumetric flow rate of the mixed fuel increases, which may lead to a decrease in combustion stability.

[0099] FIG. 6 illustrates an exemplary flame structure and chemical species distribution within a flame region according to an embodiment of the present invention, and an embodiment of the present invention may be an embodiment in which a first fuel is supplied using a first fuel nozzle (300) and a second fuel is supplied individually using a second fuel nozzle (500).

[0100] Referring to FIG. 6, when the first fuel is injected separately from the second fuel into the first air, the flame structure may form a first radical region (RZ1) where the second fuel is burned, and a second radical region (RZ2) which is a core region where the first fuel is burned inside the first radical region (RZ1) and is rich in the first fuel.

[0101] A burner (1) according to one embodiment of the present invention can prevent rapid progression to the nitrogen oxide generation pathway through oxidation reaction in the NH2 and NH radical stages and mitigate the intensity of the OH radical in the main flame area by forming a second radical region (RZ2) inside the first radical region (RZ1).

[0102] As a result, the burner according to one embodiment of the present invention may have the effect of reducing the amount of nitrogen oxides generated compared to the second comparative embodiment (when the first fuel and the second fuel are mixed and used).

[0103] Figure 7 is a graph exemplarily showing the amount of nitrogen oxides generated according to the co-firing rate based on the ammonia injection method.

[0104] Referring to FIG. 7, according to one embodiment of the present invention, the amount of nitrogen oxide generated was measured by varying the mixing ratio of the first fuel and the second fuel, in the case where the first fuel is supplied using a first fuel nozzle (300) and the second fuel is supplied individually using a second fuel nozzle (500), and in the case where the first fuel and the second fuel are mixed and supplied.

[0105] The measurement results may be as shown in Table 1 below as an example, and when expressed as a graph, they may be illustrated as shown in Fig. 7 as an example.

[0106] Mixed Fuel Supply (pmmv, O2 13%) Individual Nozzle Supply (pmmv, O2 13%) Reduction Rate (%) 5% 15 5 12 5 19.4 10% 16 6 13 5 18.7 20% 18 0 13 9 22.8 30% 21 21 63 23.1

[0107] ※ pmmv (parts per million by volume)

[0108] Referring to Table 1 together with Fig. 7, in the case where the same amount of ammonia is supplied by co-firing, the ammonia and the main fuel are supplied separately, so the burner (1) according to one embodiment of the present invention has the effect of reducing the nitrogen oxide emission concentration by more than 20% compared to the case where the second fuel (e.g., main fuel such as LNG, LPG, etc.) and the first fuel (e.g., ammonia) are mixed and supplied.

[0109] Although the present invention has been described above with reference to embodiments, the present invention is not limited to the embodiments described above, and it is understood that it can be modified and implemented by those skilled in the art without changing the technical concept of the present invention as claimed in the claims.

[0110] [Explanation of the symbol]

[0111] 1...burner 2...ro

[0112] CC...Combustion space 100...Ignition nozzle

[0113] 110...Ignition spark 120...Ignition line

[0114] 200...1st fuel nozzle 210...1st fuel supply port

[0115] 220...1st fuel injector 300...1st air nozzle

[0116] 310...1st air supply port 320...1st air nozzle

[0117] 330...Swivel section 400...2nd fuel nozzle

[0118] 410...2nd fuel supply port 420...2nd fuel injector port

[0119] 500...2nd air nozzle 510...2nd air supply port

[0120] 520...2nd air nozzle 600...3rd air nozzle

[0121] 510...3rd air supply port 520...3rd air nozzle

[0122] RZ1...1st radical zone RZ2...2nd radical zone

Claims

1. Ignition nozzle; A first fuel nozzle for injecting the first fuel; A first air nozzle for spraying first air; and A second fuel nozzle that injects second fuel; Includes, The first air nozzle is positioned between the first fuel nozzle and the second fuel nozzle, and the first fuel includes ammonia. Burner.

2. In Paragraph 1, The first fuel nozzle is positioned between the ignition nozzle and the first air nozzle, Burner.

3. In Paragraph 1, A second air nozzle further comprising a second air nozzle disposed outside the second fuel nozzle and injecting second air, Burner.

4. In Paragraph 1, The injection ports of the first fuel nozzle, the first air nozzle, and the second fuel nozzle are each arranged to have a symmetrical structure. Burner.

5. In Paragraph 1, The injection ports of the first fuel nozzle, the first air nozzle, and the second fuel nozzle are each arranged to form a virtual circle. Burner.

6. In Paragraph 5, Each of the injector openings of the first fuel nozzle, the first air nozzle, and the second fuel nozzle has the same center and different radii. Burner.

7. In Paragraph 3, It is equipped with a preheating device for preheating air, and further includes a third air nozzle for supplying preheated third air, The third air is supplied at a slower speed than the first air and the second air. Burner.

8. In Paragraph 1, The first air nozzle further includes a swirling part capable of swirling the first air being injected. Burner.

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