Ammonia combustion burner

Abstract

The present invention aims to provide an ammonia combustion burner capable of increasing ignition reliability without undergoing a secondary ammonia fuel premixing step, thereby increasing the combustion efficiency of the ammonia fuel, more effectively reducing thermal NOx and flame NOx by creating a reduction zone in the flame of the primary ammonia fuel, and enhancing flame stability. The burner comprises: a first ammonia fuel supply pipe positioned axially at the inner center of the burner body; at least two second ammonia fuel supply pipes positioned around the first ammonia fuel supply pipe; a throat and inner and outer swirling ports for air dispersion mounted on the flame side of the burner body; an air supply means for supplying air to each of the swirling ports; an ignition pilot burner; nozzles respectively coupled to the leading ends of the first ammonia fuel supply pipe and the second ammonia fuel supply pipe; and a gas inlet for gas classification installed at the rear of the burner body. The above-mentioned first and second nozzles are configured to inject primary and secondary ammonia fuel at equivalent positions to ignite and burn, and the nozzle of the first ammonia fuel supply pipe is a bluff type that injects primary ammonia fuel in a bell shape to create a reduction section in the flame in front of the nozzle, and the nozzle of the second ammonia fuel supply pipe is configured to inject secondary ammonia fuel toward an adjacent secondary ammonia nozzle by drilling a nozzle hole in an inclined surface. The ammonia combustion burner is characterized by this configuration.

Description

Technology Field

[0001] The present invention relates to a burner for burning ammonia fuel, and in particular to an ammonia combustion burner that promotes the initial combustion of ammonia by increasing ignition reliability even without premixing, and enables more effective suppression of NOx generation by creating a reducing zone within the ammonia combustion flame. Background Technology

[0003] Ammonia is also used as a fuel for burners in power generation facilities. Ammonia is easier to transport and store than hydrogen, and is competitive in terms of economic feasibility, so it is emerging as a new energy source for electricity production.

[0004] Ammonia is also a fuel with very low combustibility, which is difficult to ignite in the early stages of combustion, is a precursor to the generation of nitrogen oxides and fuel NOx, which are environmentally regulated substances, and has a calorific value of 50% and a flame propagation speed of 20% compared to LNG. Therefore, if ammonia is injected into an LNG combustion burner, the amount of nitrogen oxides, which are pollutants, can increase by 2 to 5 times compared to the existing amount, and stable combustion may be impossible, such as flame extinguishing or flame scattering during the initial ignition.

[0006] In addition, LNG burners focus on reducing thermal NOx caused by high flame temperatures and residence times in the high flame temperature range; however, since ammonia contains nitrogen components despite lacking carbon, the amount of NOx generated can increase in high-temperature combustion environments.

[0007] In other words, mixing ammonia into the burner of a boiler that has been operating stably, or replacing the entire amount with ammonia, enables flame stabilization and complete combustion, and there is a need to reduce fuel NOx.

[0008] Therefore, for a burner to use ammonia as fuel, it is required to have a structure that ensures high flame stability and is advantageous for NOx reduction.

[0009] Furthermore, since ammonia contains a large amount of nitrogen atoms, it can be easily converted into nitrogen oxides by oxidant radicals and intermediate products. Nitrogen oxides are, in themselves, major air pollutants. Thermal power plants reduce nitrogen oxides using selective catalytic reduction (SCR) systems.

[0010] However, if nitrogen oxides increase significantly compared to existing design levels during ammonia combustion, it may be difficult to treat them effectively using only existing SCR facilities, and the additional costs for catalysts, spent catalyst disposal, and ammonia for SCR are also burdensome.

[0011] Considering these circumstances, the ammonia combustion burner of Public Patent No. 10-2023-0170050 is known as a proposed prior art.

[0012] The above ammonia combustion burner is based on a burner body (1) having a funnel (2) that induces primary air introduced from the outside to be ejected toward the center of the burner as shown in FIG. 1, a first ammonia fuel supply pipe (3) located at the center of the burner body (1) to spray and spread a first ammonia fuel in front of the ejection end of the funnel (2), and a second ammonia fuel supply pipe (4) that sprays a second ammonia fuel near the approximate inner boundary line of the funnel (2).

[0013] At the tip of the first ammonia fuel supply pipe (3), a conical nozzle (5) is installed with a spray hole (5a) that sprays the first ammonia fuel in a diagonal direction, and immediately behind the nozzle (5), a flame retainer (6) is attached to guide the second ammonia fuel and air to be premixed and then sprayed.

[0014] In addition, at the tip of the second ammonia fuel supply pipe (4), a spray hole (7) is also drilled so that the second ammonia fuel is directly injected in the direction of injection of the second ammonia fuel.

[0015] And, the internal space of the burner body between the flame holder (6) and the second ammonia fuel supply pipe (4) includes a guide ring (8) that induces the second ammonia fuel injected from the second ammonia fuel supply pipe (4) and secondary air to be mixed and premixed, and then injected forward through the space between the funnel (2) and the flame holder (6).

[0016] The above nozzle hole only directly injects the first ammonia radially and diffuses it into a funnel shape; since it is not a so-called swirling induction type that injects in a swirling manner, there is a limit to increasing the combustion efficiency of the ammonia fuel.

[0017] In addition, since the nozzle is a fixed type, it is impossible to change the injection direction of the second ammonia nozzle, which limits the ability to increase the diffusion combustion efficiency of the ammonia fuel. Furthermore, if a defect occurs during use, causing functional degradation or aging that requires replacement, the replacement of the second ammonia fuel supply and injection system is unavoidable. This also entails the problem of reduced operating time and the burden of high replacement costs resulting from such replacement. Prior art literature

[0019] Published Patent No. 10-2023-0170050 The problem to be solved

[0020] The objective of the present invention is to provide an ammonia combustion burner with an improved structure that can increase the combustion efficiency of ammonia fuel by increasing ignition reliability without undergoing a secondary ammonia fuel premixing step, more effectively reduce heat NOx and flame NOx by creating a reducing zone in the flame of the primary ammonia fuel, and enhance flame stability. means of solving the problem

[0022] The present invention for achieving the above-mentioned purpose can be implemented as an ammonia combustion burner comprising: a first ammonia fuel supply pipe positioned axially at the inner center of a burner body; at least two second ammonia fuel supply pipes positioned around the first ammonia fuel supply pipe; a throat and inner and outer swivel ports for air dispersion mounted on the flame side of the burner body; an air supply means for supplying air to each of the swivel ports and a pilot burner for ignition; and nozzles respectively coupled to the tips of the first ammonia fuel supply pipe and the second ammonia fuel supply pipe; wherein the first and second nozzles are configured to inject primary and secondary ammonia fuels at equivalent positions to ignite and combust, the nozzle of the first ammonia fuel supply pipe is configured as a bluff type to inject primary ammonia fuel in a bell shape, and the nozzle of the second ammonia fuel supply pipe is mounted to inject secondary ammonia fuel toward an adjacent secondary ammonia nozzle by drilling a nozzle hole in an inclined surface.

[0023] In the ammonia burner of the present invention, the primary ammonia fuel injected and burned from the above-described bluff-type nozzle immediately rotates around the flange integrated at the nozzle end and burns, thereby creating a reduction zone in front of the nozzle.

[0024] The above reduction zone is a unique combustion phenomenon that is not seen in conventional nozzles where primary ammonia fuel is directly ejected in a funnel shape, and it is advantageous for reducing NOx generation by lowering the combustion temperature of the primary flame and enhancing flame stability.

[0025] All secondary ammonia nozzles of the present invention spray secondary ammonia fuel in one direction toward adjacent secondary ammonia fuel nozzles, causing it to strike the inner surface of the throat attached to the tip of the burner body and swirl out, thereby ensuring that the secondary ammonia fuel spreads properly without slipping and increases the combustion stability of the flame.

[0026] In addition, the secondary ammonia nozzle is connected to the end of the secondary ammonia fuel supply pipe and is a variable injection direction type that allows for fine adjustment of the injection direction of the secondary ammonia fuel even after assembly. Effects of the invention

[0028] In the ammonia combustion burner of the present invention equipped with a means for solving the problem as described above, the bluff-type nozzle mounted on the first ammonia fuel supply pipe causes the primary flame to swirl around the nozzle to form a reduction zone, thereby lowering the combustion temperature, reducing the amount of NOx generated, and further increasing the stability of the flame.

[0029] In addition, the secondary ammonia nozzle, positioned to spray in a unidirectional manner toward an adjacent nozzle, sprays the secondary ammonia fuel in a swirling manner to expand the combustion chamber and promotes mixing with secondary air, thereby enabling the complete combustion of the ammonia fuel while simultaneously reducing the amount of combustion NOx generated and confining the reduction zone of the primary flame so that it does not spread.

[0030] In addition, the fastening type secondary ammonia nozzle can increase combustion efficiency by finely adjusting the injection direction of the secondary ammonia fuel according to the combustion state. Brief explanation of the drawing

[0032] FIG. 1 is a configuration diagram of a conventional ammonia combustion burner that is the subject of comparison with the present invention. FIG. 2 is a schematic diagram of the flame of the secondary ammonia fuel premixed with the primary ammonia fuel in the configuration of the conventional burner of FIG. 1. FIG. 3 is a longitudinal front view of an ammonia combustion burner according to the present invention. FIG. 4 is a longitudinal cross-sectional view of a primary ammonia fuel nozzle of the present invention. FIG. 5 is a longitudinal cross-sectional view of a nozzle for secondary ammonia fuel according to the present invention. FIG. 6 is an arrangement of the second and third nozzles viewed from the right side of FIG. 3. FIG. 7 is a side view of the inner pivot point. FIG. 8 is a side view of the outer pivot point. Fig. 9 is a schematic diagram of the combustion of primary and secondary ammonia fuels. Specific details for implementing the invention

[0033] Next, the technical configuration of the ammonia combustion burner of the present invention will be specifically explained with reference to the drawings 3 and below, which were drawn under the basic structure.

[0034] FIG. 3 is a longitudinal front view drawn to make it easier to understand the overall configuration of the ammonia combustion burner according to the present invention.

[0035] In this drawing, a funnel-shaped tiling (12) is installed at the tip of the burner body to guide primary and secondary ammonia fuel and air introduced from the outside to spread out to aid in the combustion.

[0036] In the burner body, a first ammonia fuel supply pipe (20) is installed to penetrate in the axial direction at the center of the body, and a plurality of second ammonia fuel supply pipes (30) are arranged in a circular shape around the first ammonia fuel supply pipe (20).

[0037] The first ammonia fuel supply pipe (20) and the second ammonia fuel supply pipe (30) can be installed so that they are positioned on a single vertical line, allowing the first ammonia fuel and the second ammonia fuel to be injected simultaneously at the same location. With this structure, the first and second ammonia fuels can be injected smoothly without interfering with each other during the initial injection stage, thereby increasing combustion efficiency.

[0038] The burner body of the present invention is surrounded by an air chamber (40). The air chamber functions to temporarily retain external air flowing into the air supply port until it is divided into primary and secondary air (41)(42).

[0039] Among the above air passages, the first air passage (41) is bordered by the second air passage (42), and air inside the air chamber is supplied to the tip of the first ammonia fuel supply pipe (20) through a through hole (43) perforated on the outer wall of the burner body, thereby contributing to the diffusion injection of the primary ammonia fuel.

[0040] The second air passage (42), separated from the first air passage (41) by the outer wall of the burner body, induces some of the air inside the air chamber to flow out through the through hole (44) and spread out around the tip of the second ammonia fuel supply pipe (30).

[0041] The above-mentioned through holes (43) and through holes (44) adjust the opening and closing width of the independently equipped damper to control the primary and secondary air supply volumes, thereby ensuring that the primary and secondary ammonia fuels are supplied continuously without interruption.

[0042] The example is described as a manual damper operated from the outside of the burner body, but it is not limited to this, and if necessary for convenience in controlling the air supply volume and optimizing the air supply volume, it can be replaced with an automatic damper that opens and closes in response to the temperature of the flame.

[0043] A gas inlet (61) is installed at the rear of the burner body. Ammonia gas entering through this gas inlet (61) is divided into primary ammonia gas and secondary ammonia gas here, and the primary ammonia fuel is supplied to the introduction part of the first ammonia fuel supply pipe (20), and the secondary ammonia fuel is supplied to a plurality of second ammonia fuel supply pipes (30), thereby performing a classification function.

[0044] As seen in Fig. 4, a first nozzle (70) is installed at the tip of the first ammonia fuel supply pipe (20). The first nozzle (70) injects primary ammonia fuel supplied to the first ammonia fuel supply pipe (20) so that a reduction zone is formed in the flame in front of the first nozzle (70). A flange (71) is formed at the tip, and the area immediately behind the flange (71) is configured in a tapered shape.

[0045] The injection holes (72) of the first nozzle (70) are radially perforated in the tapered portion, and the portion where the flange (71) meets the tapered surface is a curved portion (73). When viewed longitudinally, it is a bluff shape similar to a bell shape.

[0046] In a bluff-type first nozzle (70) of this structure, the portion of the primary ammonia fuel that is sprayed into the injection hole (72) that comes into contact with the curved portion (73) momentarily swirls against the resistance of the flange (71), thereby inducing the remaining portion of the ammonia fuel to swirl around the edge of the flange (71) and helping to create a reduction zone in front of the first nozzle (70).

[0047] In other words, the nozzle (70) creates a bell-shaped flame layer so that the flame does not spread around the nozzle, and by creating a reduction zone described later in the flame layer, it lowers the combustion temperature and suppresses the generation of NOx, and also increases the stability of the flame.

[0048] As shown in FIGS. 3 and 5, the second nozzle (80) mounted on the tip of each second ammonia fuel supply pipe (30) has a tip that is inclined toward one side (81), and a spray hole (82) is drilled in the inclined surface (81). Accordingly, the secondary ammonia fuel is sprayed in a direction perpendicular to the inclined surface (81). In principle, the spray angle of the spray hole (82) is selected in the range of 15 to 90° depending on the position of the second nozzle (80).

[0049] Additionally, as shown in FIG. 6, each of the above second nozzles (80) is installed such that the inclined surface (81) is uniformly oriented clockwise or counterclockwise. Accordingly, the secondary ammonia fuel is injected in one direction toward the adjacent second nozzles and spreads and burns in a swirling manner along the inner surface of the tiling (12).

[0050] The secondary ammonia fuel injected forward toward the adjacent nozzle (80) is directed to spread further outward and mix better with the secondary air, which helps maintain the stability of the flame.

[0051] In addition, the second nozzle (80) is connected to the tip of each first ammonia fuel supply pipe (30) in a type that is fastened or in a press fit manner, so as to withstand the suction pressure of the secondary ammonia fuel and provide convenience for replacement, and the ammonia fuel injection angle of the second nozzle is adjusted to ensure flame stability and reduce NOx.

[0052] The second nozzles (80a to 80g) inject secondary ammonia fuel in alphabetical order. The flame of the secondary ammonia fuel is contained so that the primary flame does not spread sideways, thereby contributing to the formation of a reduction zone within the primary flame.

[0053] As shown in FIG. 3, the tip of the first ammonia fuel supply pipe (20) penetrates the inner pivot hole (100), and the second ammonia fuel supply pipe (30) penetrates the outer pivot hole (110).

[0054] The inner swivel section (100) is made of heat-resistant metal and promotes combustion by evenly distributing the primary air (41) required for combustion to the primary ammonia fuel injected through the first nozzle (70) in all directions, thereby inducing the primary combustion air to be injected at an angle in one direction by the radial dispersion blades (101) as shown in the example of FIG. 7.

[0055] Here, unidirectional means that the aforementioned primary ammonia fuel feeds air in the same direction as the secondary ammonia fuel described later. Accordingly, disturbance of the injected fuel that may occur when the primary ammonia fuel is injected in the opposite direction to the secondary ammonia fuel is prevented, so that the primary and secondary fuels can be smoothly injected and combusted in the forward direction.

[0057] And, the third fuel supply pipe (120) installed in the burner body between the first and second ammonia fuel supply pipes (20) (30) is intended to replenish the third ammonia fuel or to supply alternative or supplementary fuel such as LNG.

[0058] To elaborate, an inlet for introducing ammonia fuel into the first and second ammonia fuel supply pipes (20) (30) and a branch pipe (21) (22) are connected to the inlet on the side of the third fuel supply pipe (120), and a valve (V1) (V2) is installed on the branch pipe (22) on the side of the third fuel supply pipe (120).

[0059] When supplying the first ammonia fuel, the valve (V1) is closed to block the supply of the third ammonia fuel through the branch pipe, and the valve (V2) is opened so that only gaseous fuel such as LNG is supplied to the third fuel supply pipe (120). When the valve (V2) is closed and the valve (V1) is opened, the third ammonia fuel is supplied to the second fuel supply pipe (120).

[0060] The above third fuel supply pipes (120) are provided in two or more, and each base shares a chamber installed at the rear of the burner body so that the third fuel flowing into it is evenly distributed to each third fuel supply pipe (120).

[0061] As illustrated in FIG. 8, the outer swivel (110) is formed by welding a radial dispersion wing (113) between metal inner and outer rings (11) (112) with different radii, thereby ensuring that primary air is evenly distributed to secondary ammonia fuel to participate in combustion.

[0062] The above dispersion blade (113) is also formed to be inclined in the same direction as the dispersion blade (101) of the inner swivel (100) illustrated in FIG. 7 so that the secondary ammonia fuel is injected in synchronization with the primary ammonia fuel.

[0064] When ammonia fuel is introduced into the inlet while the valves (V1) and (V2) are closed, it is distributed to the first and second ammonia fuel supply pipes (20) and (30) and sprayed through the nozzles (70) and (80).

[0065] At this time, the air from the first air passage (41) and the air from the second air passage (42) are swept by the first and second ammonia fuels and injection pressure and sucked into the inner and outer swirling passages (100) (110) to supply oxygen necessary for the combustion of the ammonia fuel.

[0066] The primary ammonia fuel injected from the bluff-type first nozzle (70) acts as an air cushion, with some of it momentarily swirling around the curved section (73) to push the remaining primary amount of ammonia fuel in the centrifugal direction, and the remaining primary ammonia fuel affected by this swirls around the edge of the flange (71) and exits.

[0067] While the primary flame swirls around the flange (71) and hesitates near the front surface, the propagation speed slows down, and the secondary ammonia fuel flame applies external pressure to the flame in the center direction to confine it so that it does not spread in the circumferential direction.

[0068] In this case, what is formed is a recirculation zone (RZ) that appears inside the flame (F) in front of the first nozzle (70) exemplified in FIG. 9. The recirculation zone (RZ) delays the combustion of the primary ammonia fuel to prevent excessive combustion. As the excessive combustion of the primary ammonia fuel is prevented, the temperature of the flame is lowered and the amount of NOx generated is reduced, and as combustion occurs back in the recirculation zone, the flame does not fly away and stability is increased.

[0069] The combustion conditions of the first and second ammonia fuels are controlled by adjusting the opening width of the through holes (43) and (44) perforated at the entrance of each air passage (41) and (42) using a damper to control the amount of air supplied, thereby ensuring that an optimal amount of air is supplied for the combustion of the first and second ammonia fuels.

[0070] As explained above, the ammonia combustion burner of the present invention is equipped with a bell-shaped buffler-type nozzle in the first ammonia fuel supply pipe located at the center of the burner body, so that the flame injected and combusted from the nozzle forms a reduction zone directly in front of the nozzle, thereby preventing a rapid rise in the temperature of the flame and reducing heat NOx and flame NOx.

[0071] In addition, the inner swirling mouth installed to surround the above-mentioned buffler-type nozzle radiates primary air in one direction around the nozzle, and the secondary nozzle of the second ammonia fuel supply pipe radiates secondary air in the direction of the radiating air, causing it to swirl and burn along the inner surface of the ring throat, and the flame is confined so that it does not spread by applying external pressure to the flame in the reduction zone, thereby increasing the combustion stability of the flame. Explanation of the symbols

[0073] 20: 1st Ammonia Fuel Supply Pipe 30: 2nd Ammonia Fuel Supply Pipe 12: Tiling 40: Air chamber 21, 22: Branch pipe 41: First airway 42: Second airway 43, 44: Through hole 61: Gas inlet 70: 1st nozzle 71: Flange 80: 2nd nozzle 72, 82: Spray port 73: Curved section 81: Inclined surface 100: Inner swivel 101: Dispersing wing 110: Outer swivel 120: 3rd fuel supply pipe F: Flame RZ: Reduction Zone

Claims

Claim 1 A first ammonia fuel supply pipe positioned axially at the inner center of a burner body; at least two second ammonia fuel supply pipes arranged around the first ammonia fuel supply pipe; a tiling mounted on the flame side of the burner body; inner and outer swivel ports for primary and secondary air supply; an air supply means for supplying air to each of the swivel ports; a pilot burner for ammonia fuel ignition; first and second nozzles respectively coupled to the leading ends of the first and second ammonia fuel supply pipes; and a gas inlet for gas classification installed at the rear of the burner body; An ammonia combustion burner characterized in that the first and second nozzles are installed so as to inject primary and secondary ammonia fuel at equivalent positions, the nozzle of the first ammonia fuel supply pipe is a bluff type that injects primary ammonia fuel in a bell shape, and each nozzle of the second ammonia fuel supply pipe, which consists of multiple nozzles, is mounted such that an injection hole perforated in an inclined surface faces an adjacent nozzle. Claim 2 An ammonia combustion burner according to claim 1, wherein the bluff-type nozzle comprises a flange integrated at the tip and a nozzle body immediately behind the flange that is tapered, with a spray hole drilled on the tapered portion. Claim 3 An ammonia combustion burner characterized in that, in the second paragraph, a reduction zone is formed in front of the flange within the flame that is injected and burned from the bluff-type nozzle. Claim 4 An ammonia combustion burner according to claim 1, wherein the air supply means comprises an air supply port shared by the first and second air passages, a first air passage that guides air flowing into the air supply port to flow through a through hole to a first ammonia fuel supply pipe, and a second air passage located on the outer edge of the air passage that guides air to flow through a separate through hole to a second ammonia fuel supply pipe. Claim 5 An ammonia combustion burner according to claim 4, characterized in that each of the above-mentioned through holes adjusts the opening width with an individual damper to control the amount of air entering. Claim 6 An ammonia combustion burner according to claim 5, characterized in that the damper is either manual or automatic. Claim 7 An ammonia combustion burner according to claim 1, characterized in that a chamber shared by a second ammonia fuel supply pipe is installed at the rear of the burner body, and the rear ends of a plurality of second ammonia fuel supply pipes are welded through the chamber. Claim 8 An ammonia combustion burner according to claim 1, characterized in that a third fuel supply pipe is installed between the first and second ammonia fuel supply pipes. Claim 9 An ammonia combustion burner according to claim 8, characterized in that the third fuel supply pipe is configured for the optional supply of supplementary ammonia fuel and LNG. Claim 10 An ammonia combustion burner according to claim 1, characterized in that the primary ammonia fuel introduced through the gas inlet is supplied to a first ammonia fuel supply pipe, and the secondary ammonia fuel is supplied to a plurality of second ammonia fuel supply pipes, thereby forming a classification structure.

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