Hydrogen-fueled liquid ammonia gas turbine combustor

Abstract

A hydrogen combustion-supporting liquid ammonia gas turbine combustor comprises a liquid ammonia fuel pipeline located at a center main shaft, a first-stage axial swirler and a first-stage radial swirler coaxially arranged outside the liquid ammonia fuel pipeline, and the swirler directions are the same and used for stabilizing the liquid ammonia flame. A pre-evaporation pipeline is arranged outside to form a hydrogen gas collecting chamber, and a center space of the pre-evaporation pipeline forms a primary air channel for completing pre-mixing swirl of liquid ammonia, hydrogen and air to stabilize the liquid ammonia flame. The pre-evaporated ammonia gas in the pre-evaporation pipeline enters a secondary air channel and completes pre-mixing swirl with air through a second-stage axial swirler. Secondary air holes are formed on a wall surface of a flame tube, a large amount of air enters to burn the fuel completely and improve combustion efficiency, and simultaneously dilutes tail gas to reduce NOx emission. The present application uses liquid ammonia as fuel, realizes stable liquid ammonia flame and reduces NOx emission through liquid ammonia fuel staging, hydrogen combustion-supporting, multi-stage swirl pre-mixing and staged combustion.

Description

Technical Field

[0001] The present invention belongs to the field of thermal energy engineering technology and relates to a liquid ammonia gas turbine burner with hydrogen-assisted combustion. Background Art

[0002] Due to the high cost of hydrogen production and complex safety issues associated with its production, storage, and transportation, large-scale hydrogen fuel utilization is currently difficult. Similar to hydrogen, ammonia is a carbon-free fuel and offers significant advantages as an energy carrier: ammonia can be liquefied at room temperature at 0.8 MPa, significantly reducing transportation costs. The industry has nearly a century of experience in ammonia utilization, with well-established facilities and experience in production, transportation, and storage, and its relatively low cost. Therefore, ammonia fuel has the potential for large-scale application. However, ammonia as a fuel presents two major challenges. First, its low laminar combustion velocity results in poor combustion stability and low combustion efficiency in the combustor. Second, because ammonia molecules contain nitrogen atoms, ammonia combustion under lean-burn conditions produces extremely high NOx emissions. Current research on ammonia combustion primarily focuses on vapor-phase ammonia injection. A major drawback of this method is the need to pre-evaporate the ammonia in the supply pipeline. The evaporation and heating required prolong the startup time of gas turbines fueled by the gaseous ammonia mixture. Summary of the Invention

[0003] In order to overcome the existing technical difficulties, the purpose of the present invention is to provide a hydrogen-assisted liquid ammonia gas turbine burner, which uses liquid ammonia as fuel. Through fuel staging, hydrogen-assisted combustion, multi-stage swirl premixing, and staged combustion, it reduces nitrogen oxide emissions while improving pre-evaporation efficiency, thereby improving the economy of the gas turbine using ammonia as fuel and shortening the startup time.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A hydrogen-assisted combustion liquid ammonia gas turbine burner comprises a flame tube, a primary swirler, a pre-evaporation tube, a hydrogen gas collecting chamber, and a liquid ammonia fuel pipeline, the front end of which is provided with a liquid ammonia nozzle. The pre-evaporation tube body is cylindrical, and its side wall forms an annular cavity. The front end of the annular cavity extends into the flame tube and is provided with a fuel diffusion hole.

[0006] The hydrogen gas collecting chamber, liquid ammonia fuel pipeline and first-stage cyclone are arranged in the inner annular space of the pre-evaporation tube. The hydrogen gas collecting chamber is located upstream of the first-stage cyclone and is an annular cavity II. The wall surface of the chamber is provided with multiple fuel diffusion holes. Hydrogen diffuses along the fuel diffusion holes and is premixed with the compressed air.

[0007] Part of the liquid ammonia fuel is sprayed into the flame tube from the liquid ammonia nozzle through the liquid ammonia fuel pipeline, and the other part enters the annular cavity one, absorbs heat and pre-evaporates, completing the phase change process from liquid ammonia to ammonia gas, and the obtained ammonia gas diffuses into the flame tube through the fuel diffusion hole.

[0008] In one embodiment, secondary air holes are opened on the downstream wall of the flame tube, and part of the air compressed by the compressor enters the combustion zone through the secondary air holes to make the air excessive, thereby realizing staged combustion.

[0009] In one embodiment, the flame tube wall surfaces are overlapped layer by layer, and cooling holes are vertically opened at the connection between the layers. The end of each layer of the wall surface is set to expand outward so that air can gather at the entrance of the cooling hole. The cooling air wraps around the stacked layers of the wall surface to achieve air film cooling; part of the air compressed by the compressor enters from the tail end of the flame tube, part of it cools the flame tube wall surface through the cooling holes, and the remaining air enters from the secondary air holes.

[0010] In one embodiment, the first-stage swirler includes a first-stage axial swirler and a first-stage radial swirler, which are coaxially arranged with the liquid ammonia fuel pipeline. With reference to the air flow direction, the first-stage axial swirler is located upstream of the liquid ammonia nozzle, and the first-stage radial swirler is located downstream of the liquid ammonia nozzle. A first-stage spacer is provided between the two to fully develop the swirl, and the entire liquid ammonia nozzle is located within the swirl action area.

[0011] In one embodiment, the first-stage radial swirler can develop the mixed airflow with an axial velocity into a radial swirling flow.

[0012] In one embodiment, the central space of the pre-evaporation tube is a primary air duct, where liquid ammonia, hydrogen and air complete a premixed swirl flow; the space between the pre-evaporation tube and the flame tube is a secondary air duct, where ammonia and air derived from the endothermic phase change of liquid ammonia complete a premixed swirl flow and go together to the combustion zone for combustion.

[0013] In one embodiment, the liquid ammonia-hydrogen-air system maintains flame-stable combustion, with the added hydrogen accounting for 1.3%-5.0% of the mass of the liquid ammonia supplied to the burner. The primary combustion equivalence ratio is controlled between 1.1 and 1.3, maintaining a reducing atmosphere to reduce nitrogen oxide production. The liquid ammonia entering the pre-evaporation tube for pre-evaporation accounts for 10%-40% of the total liquid ammonia fuel supplied to the burner.

[0014] In one embodiment, the hydrogen-assisted liquid ammonia gas turbine burner further includes a secondary axial swirler, which is arranged between the pre-evaporation tube and the flame tube to form a secondary air duct.

[0015] In one embodiment, the primary axial swirler has the same rotation direction as the primary radial swirler and the opposite rotation direction to the secondary axial swirler.

[0016] In one embodiment, the outer wall of the hydrogen collecting chamber is arranged in close contact with the inner wall of the pre-evaporation tube, the inner wall of the hydrogen collecting chamber is spaced apart from the liquid ammonia fuel pipeline, the fuel diffusion holes are evenly opened on the inner wall of the hydrogen collecting chamber, and the hydrogen is evenly diffused along the radial direction of the fuel diffusion holes.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention coaxially arranges a first-stage axial swirler and a first-stage radial swirler in the liquid ammonia fuel pipeline. The liquid ammonia nozzle is located within the swirling action zone. After diffusion, ammonia gas mixes with air and enters the pre-evaporation tube. There, it comes into contact with the high-temperature air in the burner flame tube, achieving a phase transition from liquid ammonia to gaseous ammonia. The ammonia gas then diffuses through the fuel diffusion holes downstream of the second-stage axial swirler, further mixes with air, and enters the combustion zone for combustion. The present invention adds hydrogen to achieve premixing of the liquid ammonia and hydrogen. The hydrogen combustion increases the combustion zone temperature, making the liquid ammonia more easily evaporated in the pre-evaporation tube. This improves pre-evaporation efficiency, reduces fuel consumption of the liquid ammonia gas turbine, and improves the efficiency of the gas turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the main structure of a liquid ammonia gas turbine burner with hydrogen as the auxiliary fuel.

[0020] Figure 2 This is a cross-sectional view of a hydrogen-assisted liquid ammonia gas turbine burner.

[0021] Figure 3 This is a schematic diagram of the three-dimensional structure of a liquid ammonia gas turbine burner with hydrogen as the auxiliary fuel.

[0022] Figure 4 A cross-sectional view of the head of a hydrogen-assisted liquid ammonia gas turbine combustor.

[0023] Figure 5 Schematic diagram of the air flow in a hydrogen-assisted liquid ammonia gas turbine burner.

[0024] Figure 6 This is a schematic diagram of the three-dimensional structure of the first-stage radial cyclone.

[0025] Figure numerals: 11, flame tube; 12, secondary air hole; 13, cooling hole; 21, liquid ammonia fuel pipeline; 22, liquid ammonia nozzle; 31, pre-evaporation tube; 32, branch liquid ammonia pipeline; 33, ammonia fuel diffusion hole; 41, hydrogen gas collecting chamber; 42, hydrogen fuel pipeline; 43, hydrogen fuel diffusion hole; 5, first-stage axial swirler; 6, interval section; 7, first-stage radial swirler; 8, second-stage axial swirler. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention will be described below with reference to the accompanying drawings, but the protection scope of the present invention is not limited thereby.

[0027] refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 As shown, the present invention is a hydrogen-assisted liquid ammonia gas turbine burner, including a flame tube 11, a first-stage swirler, a pre-evaporation tube 31, a hydrogen gas collecting chamber 41 and a liquid ammonia fuel pipeline 21, and a liquid ammonia nozzle 22 is provided at the front end of the liquid ammonia fuel pipeline 21; the main body of the pre-evaporation tube 31 is cylindrical, and its side wall is an annular cavity 1 for pre-evaporation of liquid ammonia. Two branch liquid ammonia pipelines 32 connect the pre-evaporation tube 31 and the liquid ammonia fuel pipeline 21, and the front end of the annular cavity 1 extends into the flame tube 11 and is provided with a fuel diffusion hole 33.

[0028] The hydrogen gas collecting chamber 41, the liquid ammonia fuel pipeline 21 and the first-stage cyclone are arranged in the inner annular space of the pre-evaporator tube 31. The hydrogen gas collecting chamber 41 is located upstream of the first-stage cyclone and is an annular cavity 2. A plurality of fuel diffusion holes 43 are opened on the wall. Hydrogen diffuses along the fuel diffusion holes 43 and is premixed with the compressed air.

[0029] According to the above structure, a portion of the liquid ammonia fuel is injected into the flame tube 11 from the liquid ammonia nozzle 22 via the liquid ammonia fuel pipeline 21. The remaining portion enters the annular cavity 1, where it absorbs heat from the flame and the high-temperature air compressed by the compressor. It then pre-evaporates in the pre-evaporation tube 31, completing the phase transition from liquid ammonia to ammonia gas. The resulting ammonia gas diffuses into the flame tube 11 through the fuel diffusion holes 33. Pre-evaporating a portion of the liquid ammonia into ammonia gas reduces the instability of the liquid ammonia combustion and also serves to cool the burner.

[0030] In an embodiment of the present invention, the end of the liquid ammonia fuel pipeline 21 is a truncated cone-shaped blunt body, and the liquid ammonia nozzle 22 provides liquid ammonia fuel to the combustion zone. The liquid ammonia nozzle 22 is preferably evenly arranged on the top and side surfaces of the truncated cone-shaped blunt body, and can be evenly sprayed at different angles, which is conducive to mixing with air and hydrogen and ultimately uniform combustion.

[0031] In this embodiment of the present invention, secondary air holes 12 are formed on the downstream wall of the flame tube 11. A portion of the air compressed by the compressor enters the combustion zone through these holes, creating an excess of air and thus achieving staged combustion. The air introduced by these holes can completely burn unburned fuel under rich burn conditions, and the nitrogen oxides produced by combustion are diluted by the secondary air, thereby improving combustion efficiency and reducing nitrogen oxide emissions. The staged combustion achieved in this embodiment can significantly reduce nitrogen oxide emissions.

[0032] In an embodiment of the present invention, the wall surfaces of the flame tube 11 are overlapped layer by layer, and cooling holes 13 are vertically opened at the connection between the layers. The end of each wall layer is set to expand slightly outward so that air can gather at the entrance of the cooling hole 13. The cooling air wraps around the stacked wall layers to achieve air film cooling and improve the life of the flame tube. Part of the air compressed by the compressor enters from the tail end of the flame tube 11, and part of it cools the flame tube wall through the cooling holes 13, and the remaining air enters from the secondary air holes 12.

[0033] The present embodiment provides optimal parameters: the flame tube 11 has a wall thickness of 1.5 mm, with the walls stacked layer by layer, each layer 1.5 mm thick, and an overlap height of 80 mm. The pre-evaporation tube 31 also has a wall thickness of 1.5 mm and a fuel diffusion hole 33 with a diameter of 2 mm on its outer wall. The outer wall of the pre-evaporation tube 31 also has an axially tangential coaxial hole with a diameter of 10 mm.

[0034] In an embodiment of the present invention, the first-stage cyclone includes a first-stage axial cyclone 5 and a first-stage radial cyclone 7. The first-stage axial cyclone 5 and the first-stage radial cyclone 7 can be arranged coaxially with the liquid ammonia fuel pipeline 21. The first-stage radial cyclone 7 can be set at the front end of the pre-evaporation tube 31 so that the first-stage radial cyclone 7 can be fixed in the axial direction. With reference to the air flow direction, the first-stage axial cyclone 5 is located upstream of the liquid ammonia nozzle 22, and the first-stage radial cyclone 7 is located downstream of the liquid ammonia nozzle 22. A first-stage interval section 6 is set between the two to fully develop the swirl, and the entire liquid ammonia nozzle 22 is located in the swirl action area. The first-stage radial cyclone 7 can develop the mixed airflow with an axial velocity into a radial swirl.

[0035] In an embodiment of the present invention, the central space of the pre-evaporation tube 31 is a primary air duct, and the liquid ammonia-hydrogen-air completes a premixed swirl; the space between the pre-evaporation tube 31 and the flame tube 11 is a secondary air duct, and the ammonia gas and air obtained by the endothermic phase change of the liquid ammonia complete a premixed swirl and go to the combustion zone together for combustion.

[0036] The liquid ammonia-hydrogen-air mixture in the primary air duct maintains a stable flame. To achieve a stable liquid ammonia flame and prevent flashback caused by excessive hydrogen, the added hydrogen mass is 1.3%-5.0% of the mass of the liquid ammonia supplied to the combustion chamber. The introduction of the ammonia-air mixture into the secondary air duct moderately lowers the combustion zone temperature, achieving a fuel excess and controlling the equivalence ratio between 1.1 and 1.3. Maintaining a reducing atmosphere reduces nitrogen oxide formation. Furthermore, the liquid ammonia entering the pre-evaporation tube 31 for pre-evaporation accounts for 10%-40% of the total liquid ammonia fuel supplied to the burner.

[0037] In an embodiment of the present invention, the hydrogen-assisted liquid ammonia gas turbine combustor also includes a secondary axial swirler 8, located outside the pre-evaporation tube 31 and upstream of the ammonia fuel diffusion holes 33. Positioned between the pre-evaporation tube 31 and the flame tube 11, it forms a secondary air duct. Ammonia diffuses through the fuel diffusion holes 33 to the downstream side of the secondary axial swirler 8. Incoming air and ammonia ejected from the pre-evaporation tube 31 through the fuel diffusion holes 33 form a premixed swirl before entering the combustion zone for combustion, thereby achieving fuel staging. By controlling the rich combustion at the bottom of the combustion zone, a reducing atmosphere is maintained, reducing the formation of nitrogen oxides.

[0038] The present invention coaxially arranges a first-stage axial swirler 5 and a first-stage radial swirler 7 in a liquid ammonia fuel pipeline 21. The liquid ammonia nozzle 22 is located within the swirling zone. Ammonia diffuses, mixes with air, and enters the pre-evaporation tube 31. There, it comes into contact with the high-temperature air in the burner flame tube 11, achieving a phase transition from liquid ammonia to gaseous ammonia. The ammonia then diffuses through the ammonia fuel diffusion holes 33 to the downstream side of the second-stage axial swirler 8, where it further mixes with air and enters the combustion zone for combustion. The present invention also adds hydrogen to premix the liquid ammonia and hydrogen. The hydrogen combustion raises the combustion zone temperature, making the liquid ammonia more easily evaporated in the pre-evaporation tube 31. This improves pre-evaporation efficiency, reduces fuel consumption, and increases the efficiency of the gas turbine.

[0039] For example, the first-stage axial swirler 5 rotates in the same direction as the first-stage radial swirler 7, but in the opposite direction to the second-stage axial swirler 8. All blades are removable and replaceable. In the illustrated embodiment of the present invention, the first-stage axial swirler 5 has a blade angle θ of 50° and 12 blades; the first-stage radial swirler 7 has a blade mounting angle of 55° and 12 blades; and the second-stage axial swirler 8 has a blade angle θ of 45° and 16 blades.

[0040] The outer wall of the hydrogen plenum 41 is positioned in close proximity to the inner wall of the pre-evaporation tube 31, upstream of the primary axial cyclone 5. A gap exists between the inner wall of the hydrogen plenum 41 and the liquid ammonia fuel pipeline 21. Two hydrogen fuel pipelines 42 are located at its tail end, allowing hydrogen fuel to enter the hydrogen plenum 41. Multiple fuel diffusion holes 43 are evenly distributed along the inner wall of the hydrogen plenum 41, allowing hydrogen to diffuse evenly along the radial direction of the fuel diffusion holes 43 and premix with the compressed air.

[0041] The pre-evaporation tube 31, the liquid ammonia fuel pipeline 21, the secondary axial swirler 8, and the flame tube 11 of the present invention can be made of refractory bricks made of high-temperature resistant materials.

[0042] In summary, the present invention uses liquid ammonia as fuel and achieves stable liquid ammonia flames and reduced NOx emissions through liquid ammonia fuel staging, hydrogen combustion support, multi-stage swirl premixing, and staged combustion. This shortens the startup time of ammonia-fueled gas turbines and improves their economic efficiency.

[0043] The above are only preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention within the scope disclosed by the present invention, which fall within the scope of protection of the present invention.

Claims

1. A hydrogen-assisted combustion liquid ammonia gas turbine burner, comprising a flame tube (11), a primary cyclone, a pre-evaporation tube (31), a hydrogen gas collecting chamber (41), and a liquid ammonia fuel pipeline (21), wherein the front end of the liquid ammonia fuel pipeline (21) is provided with a liquid ammonia nozzle (22); characterized in that: The main body of the pre-evaporation tube (31) is cylindrical, and its side wall is an annular cavity 1. The front end of the annular cavity 1 extends into the flame tube (11) and is provided with a fuel diffusion hole (33); The hydrogen gas collecting chamber (41), the liquid ammonia fuel pipeline (21) and the first-stage cyclone are arranged in the inner annular space of the pre-evaporation tube (31). The hydrogen gas collecting chamber (41) is located upstream of the first-stage cyclone and is an annular cavity 2. Two hydrogen fuel pipelines (42) are arranged at the tail end of the hydrogen gas collecting chamber (41). The hydrogen fuel enters the hydrogen gas collecting chamber (41) from the cavity. A plurality of fuel diffusion holes (43) are opened on the wall of the hydrogen gas collecting chamber (41). The hydrogen diffuses along the fuel diffusion holes (43) and is premixed with the compressed air. Two branch liquid ammonia pipelines (32) are connected to the pre-evaporation pipe (31) and the liquid ammonia fuel pipeline (21). A portion of the liquid ammonia fuel is sprayed into the flame tube (11) from the liquid ammonia nozzle (22) through the liquid ammonia fuel pipeline (21), and the other portion enters the annular cavity 1, absorbs heat and pre-evaporates, completing the phase change process from liquid ammonia to ammonia gas. The obtained ammonia gas is diffused into the flame tube (11) through the fuel diffusion hole (33).

2. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 1, characterized in that: The downstream wall of the flame tube (11) is provided with secondary air holes (12), and part of the air compressed by the compressor enters the combustion zone through the secondary air holes (12) to make the air excessive, thereby realizing staged combustion.

3. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 2, characterized in that: The flame tube (11) wall surfaces are stacked layer by layer, and cooling holes (13) are vertically opened at the connection between the layers. The end of each layer of the wall surface is set to expand outward, so that air can gather at the inlet of the cooling hole (13), and the cooling air wraps around the stacked wall surfaces to achieve air film cooling; Part of the air compressed by the compressor enters from the rear end of the flame tube (11), part of it cools the flame tube wall through the cooling hole (13), and the remaining air enters from the secondary air hole (12).

4. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 1, characterized in that: The first-stage swirler comprises a first-stage axial swirler (5) and a first-stage radial swirler (7). The first-stage axial swirler (5) and the first-stage radial swirler (7) are coaxially arranged with the liquid ammonia fuel pipeline (21). With the air flow direction as a reference, the first-stage axial swirler (5) is located upstream of the liquid ammonia nozzle (22), and the first-stage radial swirler (7) is located downstream of the liquid ammonia nozzle (22). A first-stage spacing section (6) is provided between the two to fully develop the swirl, and the entire liquid ammonia nozzle (22) is located within the swirl action area. The first-stage radial swirler (7) develops the mixed airflow with a velocity along the axial direction into a radial swirl.

5. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 4, characterized in that: The central space of the pre-evaporation tube (31) is a primary air duct, where liquid ammonia, hydrogen, and air complete a premixed swirl flow; and the space between the pre-evaporation tube (31) and the flame tube (11) is a secondary air duct, where ammonia generated by the endothermic phase change of liquid ammonia and air complete a premixed swirl flow and travel together to the combustion zone for combustion.

6. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 5, characterized in that: The liquid ammonia-hydrogen-air maintains stable flame combustion. The mass of the added hydrogen is 1.3%-5.0% of the mass of the liquid ammonia supplied to the burner. The primary combustion equivalence ratio is controlled at a rich combustion condition of 1.1-1.3 to maintain a reducing atmosphere and reduce the generation of nitrogen oxides.

7. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 5, characterized in that: In terms of mass, the liquid ammonia entering the pre-evaporation tube (31) and participating in pre-evaporation accounts for 10% to 40% of the total liquid ammonia fuel supplied to the burner.

8. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 4, characterized in that: The hydrogen-assisted combustion liquid ammonia gas turbine burner further comprises a secondary axial swirler (8), which is arranged between the pre-evaporation tube (31) and the flame tube (11) to form a secondary air duct.

9. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 8, characterized in that: The first-stage axial cyclone (5) has the same rotation direction as the first-stage radial cyclone (7), and has an opposite rotation direction to the second-stage axial cyclone (8).

10. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 1, characterized in that: The outer wall of the hydrogen gas collecting chamber (41) is arranged in close contact with the inner wall of the pre-evaporation tube (31), and the inner wall of the hydrogen gas collecting chamber (41) is spaced apart from the liquid ammonia fuel pipeline (21). The fuel diffusion holes (43) are evenly arranged on the inner wall of the hydrogen gas collecting chamber (41), and hydrogen is evenly diffused radially along the fuel diffusion holes (43).

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