Hydrogen-combustion-supporting liquid ammonia gas turbine combustor

Abstract

A hydrogen combustion-supporting liquid ammonia gas turbine combustor comprises a liquid ammonia fuel pipeline located on a center main shaft, a first-stage axial swirler and a first-stage radial swirler are coaxially arranged on the periphery of the liquid ammonia fuel pipeline, and the first-stage axial swirler and the first-stage radial swirler are the same in rotation direction and used for stabilizing liquid ammonia flames. A pre-evaporation pipe and a hydrogen collecting chamber are arranged on the periphery, a primary air channel is formed in the center space of the pre-evaporation pipe for liquid ammonia, hydrogen and air to complete premixed rotational flow, and liquid ammonia flames are stabilized. The pre-evaporated ammonia gas in the pre-evaporation pipe enters the secondary air duct, and the pre-mixed rotational flow of the ammonia gas and the air is completed through the second-stage axial swirler. A secondary air hole is formed in the wall face of the flame tube, a large amount of air enters to burn out fuel, the combustion efficiency is improved, tail gas is diluted, and NOx emission is reduced. Liquid ammonia serves as fuel, and liquid ammonia flame stabilization and NOx emission reduction are achieved through liquid ammonia fuel grading, hydrogen combustion supporting, multi-stage rotational flow premixing and staged combustion.

Description

Technical Field

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

[0002] Due to the high cost of hydrogen preparation and the complex safety issues in the production, storage, and transportation processes, it is difficult to carry out large-scale hydrogen fuel utilization at this stage. Similar to hydrogen, ammonia is also a carbon-free fuel, and as an energy carrier, it has greater advantages: ammonia can be liquefied at 0.8MPa at room temperature, which greatly reduces transportation costs. The industry has nearly a hundred years of experience in the use of ammonia. Its production, transportation, storage and other facilities and experience are very mature, and the cost is relatively low. Therefore, ammonia fuel has the potential for large-scale application. However, ammonia as a fuel has two major challenges. One is that due to its low laminar combustion velocity, ammonia combustion stability is poor and the combustion efficiency in the combustion chamber is low. The second is that due to the presence of nitrogen atoms in ammonia molecules, ammonia combustion under lean combustion conditions will produce extremely high NOx emissions. At present, research on ammonia combustion mainly focuses on the gas phase injection of ammonia. One of its main disadvantages is that ammonia needs to be pre-evaporated on the supply pipeline. The need for evaporation and heating prolongs the start-up time of gas turbines fueled by gaseous ammonia mixtures. 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 combustion liquid ammonia gas turbine burner, which uses liquid ammonia as fuel, reduces nitrogen oxide emissions through fuel staging, hydrogen-assisted combustion, multi-stage swirl premixing, and staged combustion, while improving pre-evaporation efficiency, improving the economy of gas turbines using ammonia as fuel, and shortening the startup time.

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

[0005] A hydrogen-assisted combustion liquid ammonia gas turbine burner comprises a flame tube, a primary cyclone, a pre-evaporation tube, a hydrogen gas collecting chamber and a liquid ammonia fuel pipeline, wherein the front end of the liquid ammonia fuel pipeline is provided with a liquid ammonia nozzle; the pre-evaporation tube body is cylindrical, and its side wall is an annular cavity 1, the front end of the annular cavity 1 extends into the flame tube and is provided with a fuel diffusion hole;

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

[0007] A portion 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 portion enters the annular cavity 1, absorbs heat for pre-evaporation, and completes the phase change process from liquid ammonia to ammonia gas. The resulting 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, and 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, and 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 primary swirler includes a primary axial swirler and a primary radial swirler, which are coaxially arranged with the liquid ammonia fuel pipeline. With the air flow direction as a reference, the primary axial swirler is located upstream of the liquid ammonia nozzle, and the primary radial swirler is located downstream of the liquid ammonia nozzle. A primary spacing section is arranged between the two to fully develop the swirl, and the entire liquid ammonia nozzle is located in the swirl action area.

[0011] In one embodiment, the primary radial swirler can develop the mixed airflow with a velocity along the axial direction into a radial swirling flow.

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

[0013] In one embodiment, the liquid ammonia-hydrogen-air maintains flame-stable combustion, and the mass of the added hydrogen is 1.3%-5.0% of the mass of the liquid ammonia supplied to the burner; the equivalence ratio of the primary combustion is controlled at 1.1-1.3, and the reduction atmosphere is maintained to reduce the generation of nitrogen oxides. The proportion of liquid ammonia entering the pre-evaporation tube for pre-evaporation is 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 disposed 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 gas collecting chamber is arranged in close contact with the inner wall of the pre-evaporation tube, the inner wall of the hydrogen gas collecting chamber is spaced apart from the liquid ammonia fuel pipeline, the fuel diffusion holes are evenly arranged on the inner wall of the hydrogen gas collecting chamber, and the hydrogen is evenly diffused radially along 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 a liquid ammonia fuel pipeline, and the liquid ammonia nozzle is located in the swirling action area. After ammonia diffuses, it mixes with air and enters the pre-evaporation tube, and contacts with the high-temperature air of the burner flame tube to realize the phase change process from liquid ammonia to ammonia. Ammonia diffuses to the downstream of the second-stage axial swirler through the fuel diffusion hole, and enters the combustion zone for combustion after further mixing with air. The present invention adds hydrogen to realize the premixing of liquid ammonia and hydrogen. Through the combustion of hydrogen, the temperature of the combustion zone is increased, so that liquid ammonia is more easily evaporated in the pre-evaporation tube, the pre-evaporation efficiency is improved, the fuel consumption of the liquid ammonia gas turbine is reduced, and the efficiency of the gas turbine is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the main structure of a hydrogen-assisted liquid ammonia gas turbine burner.

[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 combustion aid.

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

[0023] Figure 5 Schematic diagram of 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 a 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, primary axial swirler; 6, interval section; 7, primary radial swirler; 8, secondary axial swirler. DETAILED DESCRIPTION

[0026] The specific implementation modes of the present invention are described below in conjunction with 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 combustion liquid ammonia gas turbine burner, including a flame tube 11, a first-stage swirler, a pre-evaporator 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-evaporator 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-evaporator tube 31 and the liquid ammonia 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 part 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 part enters the annular cavity 1, absorbs the heat of the flame and the high-temperature air compressed by the compressor, and pre-evaporates in the pre-evaporation tube 31 to complete the phase change process from liquid ammonia to ammonia gas. The obtained ammonia gas diffuses to the flame tube 11 through the fuel diffusion hole 33. By pre-evaporating part of the liquid ammonia into ammonia gas, the instability of liquid ammonia combustion is reduced, and at the same time, it can play a role in cooling 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 the embodiment of the present invention, a secondary air hole 12 is opened on the downstream wall of the flame tube 11, and part of the air compressed by the compressor enters the combustion zone through the secondary air hole 12 to make the air excessive, thereby realizing staged combustion. The air introduced by the secondary air hole 12 can burn out the unburned fuel under the rich combustion condition, and the nitrogen oxides generated by the combustion can be diluted by the secondary air, thereby improving the combustion efficiency and reducing the emission of nitrogen oxides. The staged combustion realized in this embodiment can greatly reduce the emission of nitrogen oxides.

[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 layer of the wall surface is set to expand slightly outward so that air can gather at the entrance of the cooling hole 13. The cooling air wraps the stacked wall surfaces layer by layer to achieve air film cooling and improve the life of the flame tube. Part of the air compressed by the compressor enters from the rear end of the flame tube 11, and part of it cools the flame tube wall surface through the cooling holes 13, and the remaining air enters from the secondary air holes 12.

[0033] The embodiment of the present invention provides a better parameter, the flame tube 11 has a wall thickness of 1.5 mm, the wall surfaces overlap layer by layer, the wall surface thickness of each layer is 1.5 mm, and the wall surface overlap height is 80 mm. The pre-evaporation tube 31 has a wall thickness of 1.5 mm, and the outer wall surface of the pre-evaporation tube 31 is provided with a fuel diffusion hole 33, the diameter of the fuel diffusion hole 33 is 2 mm, and the outer wall of the pre-evaporation tube 31 is provided with an axial tangential coaxial hole, the hole diameter is 10 mm.

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

[0035] In an embodiment of the present invention, the central space of the pre-evaporator tube 31 is a primary air duct, and the liquid ammonia-hydrogen-air completes a premixed swirl; the space between the pre-evaporator 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 liquid ammonia complete a premixed swirl and go to the combustion zone together for combustion.

[0036] Liquid ammonia-hydrogen-air in the primary air duct maintains stable flame combustion. In order to achieve a better stable liquid ammonia flame and prevent flashback caused by excessive hydrogen, the mass of added hydrogen is 1.3%-5.0% of the mass of liquid ammonia supplied to the combustion chamber. The entry of ammonia-air mixture in the secondary air duct can moderately reduce the temperature of the combustion zone, make the fuel excessive, and control the equivalence ratio at 1.1-1.3. Maintaining a reducing atmosphere can reduce the generation of nitrogen oxides. In addition, the proportion of liquid ammonia entering the pre-evaporation tube 31 for pre-evaporation is 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 burner further includes a secondary axial swirler 8, which is arranged outside the pre-evaporation tube 31 and upstream of the ammonia fuel diffusion hole 33. It is located between the pre-evaporation tube 31 and the flame tube 11 to form a secondary air duct, and ammonia diffuses to the downstream of the secondary axial swirler 8 through the fuel diffusion hole 33. The incoming air and the ammonia sprayed from the pre-evaporation tube 31 through the fuel diffusion hole 33 complete the premixed swirl and enter the combustion zone for combustion, thereby realizing fuel grading. By controlling the concentrated combustion at the bottom of the combustion zone, a reducing atmosphere is maintained and the generation of nitrogen oxides is reduced.

[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 2, and the liquid ammonia nozzle 22 is located in the swirling action area. After ammonia diffuses, it mixes with air and enters the pre-evaporation tube 31, and contacts with the high-temperature air of the burner flame tube 11, so as to realize the phase change process from liquid ammonia to ammonia. Ammonia diffuses to the downstream of the second-stage axial swirler 8 through the ammonia fuel diffusion hole 33, and enters the combustion zone for combustion after further mixing with air. The present invention adds hydrogen to realize the premixing of liquid ammonia and hydrogen, and through the combustion of hydrogen, the temperature of the combustion zone is increased, so that liquid ammonia is more easily evaporated in the pre-evaporation tube 31, the pre-evaporation efficiency is improved, the fuel consumption of the liquid ammonia gas turbine is reduced, and the efficiency of the gas turbine is improved.

[0039] For example, the primary axial swirler 5 has the same rotation direction as the primary radial swirler 7 and the opposite rotation direction as the secondary axial swirler 8. Both are flat blades that can be removed and replaced. In the illustrated embodiment of the present invention, the blade angle θ of the primary axial swirler 5 is 50°, and the number of blades is 12; the blade installation angle of the primary radial swirler 7 is 55°, and the number of blades is 12; the blade angle θ of the secondary axial swirler 8 is 45°, and the number of blades is 16.

[0040] The outer wall of the hydrogen gas collecting chamber 41 is arranged close to the inner wall of the pre-evaporation tube 31 and is located upstream of the primary axial cyclone 5. The inner wall of the hydrogen gas collecting chamber 41 is spaced apart from the liquid ammonia fuel pipeline 21, and two hydrogen fuel pipelines 42 are arranged at the tail end thereof, through which hydrogen fuel can enter the hydrogen gas collecting chamber 41. A plurality of 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 to complete premixing with the compressed air.

[0041] The pre-evaporation tube 31, the liquid ammonia fuel pipeline 2, 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 flame and reduced NOx emissions through liquid ammonia fuel staging, hydrogen combustion-supporting, multi-stage swirl premixing, and combustion staging, shortens the start-up time of a gas turbine using ammonia as fuel, and improves the economy of the gas turbine.

[0043] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the scope disclosed by the present invention, which all belong to the protection scope 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 primary 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 primary cyclone and is an annular cavity II. A plurality of fuel diffusion holes (43) are opened on the wall surface. Hydrogen diffuses along the fuel diffusion holes (43) and is premixed with the compressed air. 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 to absorb heat for pre-evaporation, completing the phase change process from liquid ammonia to ammonia gas. The resulting 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 entrance 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 primary swirler comprises a primary axial swirler (5) and a primary radial swirler (7). The primary axial swirler (5) and the primary radial swirler (7) are coaxially arranged with the liquid ammonia fuel pipeline (21). With reference to the air flow direction, the primary axial swirler (5) is located upstream of the liquid ammonia nozzle (22), and the primary radial swirler (7) is located downstream of the liquid ammonia nozzle (22). A primary spacing section (6) is arranged between the two to allow the swirl to fully develop. The entire liquid ammonia nozzle (22) is located within the swirl action area. The primary radial swirler (7) allows the mixed airflow with a velocity along the axial direction to develop into a radial swirl.

5. The hydrogen-assisted liquid ammonia gas turbine burner according to claim 4 is 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; the space between the pre-evaporation tube (31) and the flame tube (11) is a secondary air duct, where ammonia and air resulting from the endothermic phase change of liquid ammonia complete a premixed swirl flow and go to the combustion zone together 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. In terms of mass, the mass of added hydrogen is 1.3%-5.0% of the mass of 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), wherein the secondary axial swirler (8) 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 swirler (5) has the same rotation direction as the first-stage radial swirler (7), and has an opposite rotation direction to the second-stage axial swirler (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), 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 the hydrogen is evenly diffused radially along the fuel diffusion holes (43).

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