A low-pollution burner structure

Abstract

The present invention relates to a low-pollution burner structure, comprising: a burner casing, a flame tube combustion section, a flame tube spiral section, a flame tube assembly section, a baffle plate, and a burner head; the flame tube spiral section is located between the flame tube combustion section and the flame tube assembly section, one end of the flame tube spiral section is connected to the flame tube combustion section through the front end of a spiral hollow tube, and the other end is connected to the flame tube assembly section through the rear end of the spiral hollow tube. The beneficial effects of the present invention are as follows: the present invention improves the flexibility and uniformity of fuel regulation and reduces pollution emissions. The main fuel and the supplementary fuel can use the same fuel or different fuels, which improves the flexibility of fuel application; and the supplementary fuel is in a partially premixed combustion mode, which not only reduces the combustion temperature and NO X emissions, but also eliminates risks such as flashback.

Description

Technical Field

[0001] The present invention relates to the technical field of advanced manufacturing equipment, and more precisely, it relates to a low-pollution burner structure. Background Art

[0002] With the energy shortage and the worldwide attention to environmental issues, the requirements for the pollution emission performance and combustion efficiency of gas turbines in various countries are becoming increasingly strict. Generally, it is required that in the load range above 50% of the gas turbine, the combustion chamber emissions can be maintained at a low level while maintaining a high combustion efficiency. For gaseous fuels (such as methane), in order to achieve low emission levels, premixed combustion technology is widely used. Although premixed combustion can achieve relatively low emission levels, during the operation of the unit, it is prone to cause the mixing gas velocity to be less than the flame velocity due to various faults (such as nozzle blockage, fouling, or design defects), and then flashback occurs, resulting in damage to the burner. Premixed combustion is more likely to generate thermoacoustic oscillation phenomena. The interaction between the heat release rate fluctuation and the pressure fluctuation forms combustion noise with a larger amplitude and greater energy, which damages the structure of the burner body.

[0003] Improving the multi-fuel adaptability of gas turbines is an important development direction for ground gas turbine burners. It can reasonably utilize various gaseous and liquid fuels on the earth, save energy, and improve the economy and market competitiveness of gas turbines. The pollution emission requirements for dual-fuel burners are more stringent than those for single-fuel burners. When operating with liquid fuels, it is required to meet the pollution emission requirements of liquid fuels; when operating with gaseous fuels, it is required to meet the pollution emission requirements of gaseous fuels. Currently, there are not many literatures and patents on low-pollution dual-fuel burners. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and propose a low-pollution burner structure.

[0005] In the first aspect, a low-pollution burner structure is provided, including: a burner casing, a flame tube combustion section, a flame tube spiral section, a flame tube assembly section, a baffle, and a burner head; the flame tube spiral section is located between the flame tube combustion section and the flame tube assembly section. One end of the flame tube spiral section is connected to the flame tube combustion section through the front end of the spiral hollow tube, and the other end is connected to the flame tube assembly section through the rear end of the spiral hollow tube;

[0006] The flame tube spiral section is composed of a plurality of spiral section hollow pipes, a plurality of supplementary fuel intake pipes, and a plurality of supplementary fuel injection ports; a plurality of supplementary fuel injection ports are evenly distributed along the spiral direction on the side of the spiral section hollow pipe close to the axis of the flame tube; the fuel intake pipes are located on the side of the spiral section hollow pipe far from the axis of the flame tube.

[0007] Preferably, the axis of the hollow pipe of the spiral section coincides with the axis of the flame tube. The diameter of the spiral center line of the hollow pipe of the spiral section is equal to the diameter of the middle line of the wall surface of the combustion section of the flame tube, and the outer diameter of the hollow pipe of the spiral section is the same as the wall thickness of the flame tube wall.

[0008] Preferably, the plurality of supplementary fuel inlet pipes include: a first-way supplementary fuel inlet pipe, a second-way supplementary fuel inlet pipe, and a third-way supplementary fuel inlet pipe.

[0009] Preferably, the burner head is composed of a main fuel system, a primary swirler, and a secondary swirler, etc. The primary swirler has 6 straight blades, the secondary swirler has 8 straight blades, and the swirl directions of the primary swirler and the secondary swirler are opposite; the main fuel system is composed of a main fuel inlet pipe and a main fuel injection port, and the number of main fuel injection ports is 6.

[0010] In a second aspect, a working method of a low-pollution burner structure as described in the first aspect is provided, including:

[0011] S1. After the air enters from the annular cavity between the burner casing 1 and the flame tube, a part of it directly enters the flame tube from the gap of the hollow pipe 34 of the spiral section, and the other part enters the flame tube from the primary swirler and the secondary swirler;

[0012] S2. After the main fuel enters from the main fuel inlet pipe, it is sprayed into the interior of the flame tube from the main fuel injection port, mixes and burns with the air coming from the primary swirler and the secondary swirler. The combustion mode is diffusion combustion, which has good stability, can provide a stable ignition source for the supplementary fuel combustion, and the main fuel injection port corresponds one-to-one with the number and axial position of the primary swirl vanes, can form a flame structure with a smaller scale, and can reduce partial NOx emissions;

[0013] S3. The supplementary fuel enters the spiral section hollow pipe from the supplementary fuel inlet pipe and is sprayed into the interior of the flame tube from the supplementary fuel injection ports evenly distributed on the spiral section hollow pipe, and mixes and burns with the high-temperature flue gas, unburned air coming from the burner head, and the air coming from the gap of the spiral section hollow pipe. This combustion mode is partial premixed combustion, which can greatly reduce the combustion temperature and NOx emissions, and because the supplementary fuel and air are premixed in a larger space of the flame tube, there is no risk of flashback.

[0014] Preferably, in S1, the air ratio of the two parts is adjusted by changing the pitch or gap of the hollow pipe of the spiral section.

[0015] Preferably, in S2 and S3, the main fuel and the supplementary fuel are liquid fuel or gaseous fuel. The liquid fuel includes aviation kerosene, and the gaseous fuel includes natural gas, hydrogen, and ammonia. The supplementary fuel can be the same as or different from the main fuel.

[0016] In a third aspect, a control method for a supplementary fuel intake pipeline of a low-pollution burner structure as described in the first aspect is provided, which is characterized by including:

[0017] S1. After the main fuel and the primary and secondary swirler air are ignited and stably combusted, as the fuel increases, the power of the combustion chamber increases, and the rotational speed of the gas turbine also gradually increases; when the rotational speed rises to the rated rotational speed, at this time, the work done and the power consumed by the gas turbine cancel each other out, and at this time, the fuel flow rate is continuously increased, and the main fuel combustion is continuously maintained;

[0018] S2. When the work done by the gas turbine is 25% of the rated load, open the control valve of the first supplementary fuel intake pipeline so that the main fuel and the first supplementary fuel are both kept in a combustion state;

[0019] S3. When the work done by the gas turbine is 50% of the rated load, open the control valve of the second supplementary fuel intake pipeline so that the main fuel, the first supplementary fuel, and the second supplementary fuel are all kept in a combustion state;

[0020] S4. When the work done by the gas turbine is 75% of the rated load, open the control valve of the third supplementary fuel intake pipeline so that the main fuel, the first supplementary fuel, the second supplementary fuel, and the third supplementary fuel are all kept in a combustion state.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The present invention improves the flexibility and uniformity of fuel regulation and reduces pollution emissions. The main fuel and the supplementary fuel can use the same fuel or different fuels, which improves the flexibility of fuel application; and the supplementary fuel is in a partial premixed combustion mode, which not only reduces the combustion temperature and NO X emissions, but also eliminates risks such as flashback.

[0023] 2. The present invention improves the thermoacoustic oscillation during combustion. Since the spiral section of the flame tube is a spiral structure with certain elasticity and deformability, it can change the propagation frequency and phase of sound waves in the flame tube, and can effectively prevent the generation of thermoacoustic oscillation.

[0024] 3. The present invention absorbs the thermal deformation of the flame tube, releases the thermal stress of the flame tube, and improves the service life of the flame tube. Since the spiral section of the flame tube is a spiral structure with certain elasticity and deformability, it can absorb the displacement and deformation of the flame tube caused by the temperature difference, effectively release the stress of the flame tube, and improve the service life of the flame tube.

[0025] 4. The present invention improves the adjustability of air distribution. After the air enters the annular chamber, a part of it directly enters the combustion chamber through the gap of the spiral hollow pipe, and the other part enters the combustion chamber through the primary and secondary swirlers. The air distribution of each part can be adjusted by changing the pitch (or gap) of the spiral hollow pipe, so as to finely adjust the air volume in each area of the combustion chamber. Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of a low-pollution burner;

[0027] Figure 2 is a schematic structural diagram of the spiral section of the combustion chamber;

[0028] Figure 3 is a schematic structural diagram of the burner head;

[0029] Description of the reference numerals: 1 - burner casing; 2 - combustion section of the combustion chamber; 3 - spiral section of the combustion chamber; 4 - assembly section of the combustion chamber; 5 - baffle; 6 - burner head; 31 - first supplementary fuel inlet pipe; 32 - second supplementary fuel inlet pipe; 33 - third supplementary fuel inlet pipe; 34 - hollow pipe of the spiral section; 35 - supplementary fuel injection port; 36 - front end of the spiral hollow pipe; 37 - rear end of the spiral hollow fuel pipe; 61 - main fuel inlet pipe; 62 - main fuel injection port; 63 - primary swirler; 64; outer partition of the primary swirler; 65 - secondary swirler; 66 - outer partition of the secondary swirler. Detailed Embodiments

[0030] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only for helping to understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0031] Embodiment 1:

[0032] A low-pollution burner structure, as Figure 1 shown, includes: a burner casing 1, a combustion section 2 of the combustion chamber, a spiral section 3 of the combustion chamber, an assembly section 4 of the combustion chamber, a baffle 5 and a burner head 6; the spiral section 3 of the combustion chamber is located between the combustion section 2 of the combustion chamber and the assembly section 4 of the combustion chamber. One end of the spiral section 3 of the combustion chamber is connected to the combustion section 2 of the combustion chamber through the front end 36 of the spiral hollow pipe, and the other end is connected to the assembly section 4 of the combustion chamber through the rear end 37 of the spiral hollow pipe, providing a fixed support for the spiral section 3 of the combustion chamber.

[0033] As Figure 2As shown in the figure, the spiral section 3 of the flame tube is composed of a number of hollow spiral-section pipes 34, a number of supplementary fuel intake pipes, and a number of supplementary fuel injection ports 35; a number of supplementary fuel injection ports 35 are evenly distributed along the spiral direction on the side of the hollow spiral-section pipe 34 close to the axis of the flame tube for injecting supplementary fuel into the flame tube; the fuel intake pipes are located on the side of the hollow spiral-section pipe 34 away from the axis of the flame tube.

[0034] The axis of the hollow spiral-section pipe 34 coincides with the axis of the flame tube. The diameter of the spiral center line of the hollow spiral-section pipe 34 is equal to the diameter of the midline of the wall surface of the combustion section 2 of the flame tube, and the outer diameter of the pipe of the hollow spiral-section pipe 34 is the same as the wall thickness of the flame tube.

[0035] The number of supplementary fuel intake pipes includes: the first-way supplementary fuel intake pipe 31, the second-way supplementary fuel intake pipe 32, and the third-way supplementary fuel intake pipe 33.

[0036] As Figure 3 shown in the figure, the burner head 6 is composed of a main fuel system, a primary swirler 63, and a secondary swirler 65. The primary swirler 63 has 6 straight vanes, the secondary swirler 65 has 8 straight vanes, and the swirling directions of the primary swirler 63 and the secondary swirler 65 are opposite. The main fuel system is composed of a main fuel inlet pipe 61 and a main fuel injection port 62, and the number of main fuel injection ports is 6. The main fuel enters from the main fuel inlet pipe 61 and is sprayed into the interior of the flame tube from the main fuel injection port 62, and is mixed and burned with the air coming from the primary and secondary swirlers. The main fuel can be a liquid fuel such as aviation kerosene, or a gaseous fuel such as natural gas, hydrogen, ammonia, etc.

[0037] The supplementary fuel enters the hollow spiral-section pipe 34 from the supplementary fuel intake pipe and is sprayed into the interior of the flame tube from the supplementary fuel injection ports 35 evenly distributed on the hollow spiral-section pipe 34, and is mixed and burned with the high-temperature flue gas, unburned air coming from the burner head 6, and the air coming from the gap of the hollow spiral-section pipe 34, which can ensure as uniform combustion as possible and reduce NO X emissions. The supplementary fuel can be a liquid fuel such as aviation kerosene, or a gaseous fuel such as natural gas, hydrogen, ammonia, etc. The supplementary fuel can be the same as or different from the main fuel.

[0038] After the air enters from the annular cavity between the burner casing 1 and the flame tube, a part of it directly enters the flame tube from the gap of the hollow spiral-section pipe 34, and the other part enters the flame tube from the primary swirler 63 and the secondary swirler 65. The proportion of the two parts of air can be adjusted by changing the pitch (or gap) of the hollow spiral-section pipe 34.

[0039] The main fuel forms a diffusion combustion with the air of the primary and secondary swirler, which is mainly used to provide a stable ignition source. The supplementary fuel can be mixed with the high-temperature flue gas coming from the burner head 6, the unburned air, and the air coming through the gap of the spiral hollow pipe 34 and then burned, forming a partial premixed combustion mode, which can greatly reduce the flame temperature and NOx emissions. Moreover, the supplementary fuel and air are premixed in the large space of the flame tube, which can prevent combustion phenomena such as flashback.

[0040] Embodiment 2:

[0041] There are several spiral-segment hollow pipes 34 on the spiral segment ( Figure 1 taking one spiral-segment hollow pipe 34 as an example), and there can be several supplementary fuel inlet pipes on the outside of each spiral-segment hollow pipe 34 ( Figure 2 taking 3 supplementary fuel inlet pipes as an example, defined as the first-way supplementary fuel inlet pipe 31; the second-way supplementary fuel inlet pipe 32 and the third-way supplementary fuel inlet pipe 33), and the opening condition of the supplementary fuel pipes can be determined according to the load of the gas turbine:

[0042] (1) After the main fuel and the air of the primary and secondary swirler burn, as the fuel increases, the power of the combustion chamber increases, and the rotational speed of the gas turbine also gradually increases; when the rotational speed rises to the rated rotational speed, at this time, the work done and the work consumed by the gas turbine cancel each other out. At this time, if the fuel flow rate is continued to be increased, the main fuel combustion is continued; (2) When the work done by the gas turbine is 25% of the rated load, open the control valve of the first-way supplementary fuel inlet pipe 31 to keep the main fuel and the first-way supplementary fuel burning simultaneously; (3) When the work done by the gas turbine is 50% of the rated load, open the control valve of the second-way supplementary fuel inlet pipe 32 to keep the main fuel, the first-way supplementary fuel, and the second-way supplementary fuel burning simultaneously; (4) When the work done by the gas turbine is 75% of the rated load, open the control valve of the third-way supplementary fuel inlet pipe 32 to keep the main fuel, the first-way supplementary fuel, the second-way supplementary fuel, and the third-way supplementary fuel burning simultaneously.

Claims

1. A low-pollution burner structure, characterized in that, it includes: a burner casing (1), a flame tube combustion section (2), a flame tube spiral section (3), a flame tube assembly section (4), a baffle (5) and a burner head (6); The flame tube spiral section (3) is located between the flame tube combustion section (2) and the flame tube assembly section (4). One end of the flame tube spiral section (3) is connected to the flame tube combustion section (2) through the front end of the spiral hollow tube (36), and the other end is connected to the flame tube assembly section (4) through the rear end of the spiral hollow tube (37); The flame tube spiral section (3) is composed of a number of spiral section hollow pipes (34), a number of supplementary fuel intake pipes and a number of supplementary fuel injection ports (35); a plurality of supplementary fuel injection ports (35) are evenly distributed along the spiral direction on the side of the spiral section hollow pipe (34) close to the axis of the flame tube; the supplementary fuel intake pipes are located on the side of the spiral section hollow pipe (34) away from the axis of the flame tube; the axis of the spiral section hollow pipe (34) coincides with the axis of the flame tube, the median diameter of the spiral section hollow pipe (34) is equal to the median diameter of the wall surface of the flame tube combustion section (2), and the pipe diameter of the spiral section hollow pipe (34) is consistent with the wall thickness of the flame tube; the burner head (6) is composed of a main fuel system, a primary swirler (63) and a secondary swirler (65). The primary swirler (63) has 6 straight blades, the secondary swirler (65) has 8 straight blades, and the swirl directions of the primary swirler (63) and the secondary swirler (65) are opposite; The working method of the low-pollution burner structure includes: S1. After the air enters from the annular cavity between the burner casing (1) and the flame tube, a part of the air directly enters the flame tube through the gap of the spiral section hollow pipe (34), and the other part enters the flame tube through the primary swirler (63) and the secondary swirler (65); In S1, the air ratio of the two parts is adjusted by changing the pitch or gap of the spiral section hollow pipe (34); S2. After the main fuel enters from the main fuel inlet pipe (61), it is sprayed into the interior of the flame tube from the main fuel injection port (62), and is mixed and burned with the air coming from the primary swirler (63) and the secondary swirler (65) to form a diffusion combustion mode; S3. The supplementary fuel enters the spiral section hollow pipe (34) from the supplementary fuel intake pipe, and is sprayed into the interior of the flame tube from the supplementary fuel injection ports (35) evenly distributed on the spiral section hollow pipe (34), and is mixed and burned with the high-temperature flue gas, unburned air coming from the burner head (6) and the air coming from the gap of the spiral section hollow pipe (34) to form a partial premixed combustion mode.

2. The low-pollution burner structure according to claim 1, characterized in that, the number of the supplementary fuel intake pipes includes: a first-way supplementary fuel intake pipe (31), a second-way supplementary fuel intake pipe (32) and a third-way supplementary fuel intake pipe (33).

3. The low-pollution burner structure according to claim 1, characterized in that, In S2 and S3, the main fuel and the supplementary fuel are liquid fuels or gaseous fuels. The liquid fuel includes aviation kerosene, and the gaseous fuels include natural gas, hydrogen, and ammonia. The main fuel combustion and the supplementary fuel may be the same or different.

Images