Flexible peak-shaving burner and method of operation thereof

Abstract

The application discloses a flexible peak-shaving combustor and a working method thereof, and relates to the technical field of combustors, which comprises a center ventilation pipe and an outer pipe arranged in sequence from inside to outside, the center ventilation pipe is communicated with a pulverized coal gas flow mixing inlet, and the center ventilation pipe is used for conveying air for a combustion device; the outer pipe is communicated with an air inlet, and the outer pipe is used for conveying fuel for the combustion device; a plurality of baffles are arranged on the circumference of the outer pipe and are distributed in a ring array with the center ventilation pipe as the center; and each baffle moves synchronously along a straight line radially to the center ventilation pipe as the load demand decreases. The application changes the distance between the baffles and the center ventilation pipe, adjusts the flow of the pulverized coal mixed gas flow, and meets the demand of balancing energy supply of a thermal power plant; a primary air pipe with a thick end and a thin end is designed to convey the pulverized coal mixed gas flow, a speed difference is utilized, and the mixing effect of the pulverized coal mixed gas flow and the air is improved.

Description

Technical Field

[0001] This invention relates to the field of burner technology, and in particular to a flexible peak-shaving burner and its operating method. Background Technology

[0002] Thermal power plants are important energy conversion facilities that generate heat energy by burning fuel and then converting it into electrical energy. In the operation of a thermal power plant, the burner plays a crucial role, transforming fuel into high-temperature, high-pressure gas through a precise combustion process, which drives the generator rotor to produce electricity. Flexible peak-shaving technology is particularly important in this process. Through intelligent control systems, it monitors the grid load in real time and flexibly adjusts the output power of the thermal power plant to adapt to fluctuating power system demands. This peak-shaving capability allows thermal power plants to provide additional electricity during peak demand periods and reduce output during off-peak periods, thus achieving power system balance.

[0003] Regarding the aforementioned issues, Chinese Patent CN201810615125.3 discloses a flexible peak-shaving burner and its operating method, employing the principle of an axially movable sleeve wall to adjust the cross-sectional area of ​​the burner's flow channel, enabling stable combustion under lower loads. While the aforementioned prior art can achieve peak shaving, the movement of the primary and secondary air channels creates a distance difference between them, preventing fuel from contacting air immediately and reducing mixing efficiency. Therefore, this invention proposes a flexible peak-shaving burner and its operating method. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible peak-shaving burner and its operating method to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A flexible peak-shaving burner includes a central ventilation pipe and an outer pipe arranged sequentially from the inside to the outside. The central ventilation pipe is connected to the coal powder gas mixing inlet to supply air to the combustion equipment, and the outer pipe is connected to the air inlet to supply fuel to the combustion equipment. Several baffles are arranged in a ring array around the central ventilation pipe on the circumferential surface of the outer pipe. As the load demand decreases, each baffle moves synchronously toward the central ventilation pipe in a straight line along the radial direction of the central ventilation pipe.

[0007] Preferably, a drive ring is movably fitted onto the circumferential surface of the outer tube. One end of the drive ring has an arc-shaped drive groove that penetrates the baffle. The number of arc-shaped drive grooves is the same as the number of baffles. With the center of the central ventilation pipe as the inner direction and the center of the central ventilation pipe as the outer direction, the arc-shaped drive grooves are inclined inward. A slider is slidably connected inside the arc-shaped drive groove, and the slider is fixedly connected to the baffle. A fixing ring is installed at one end of the drive ring. One end of the fixing ring has a through-hole limiting straight groove. The limiting straight groove is located on the extension line of the baffle, and the number of limiting straight grooves is the same as the number of baffles. The baffle is slidably assembled in the limiting straight groove.

[0008] Preferably, a gear ring is fixedly sleeved on the circumferential surface of the drive ring, and a gear is meshed with the gear ring. The diameter of the gear is smaller than the diameter of the gear ring, which plays a role in reducing speed and increasing output torque. The gear is fixedly connected to the motor shaft of the servo motor, and the servo motor is fixedly mounted on the circumferential surface of the outer tube.

[0009] Preferably, several primary air ducts are evenly installed on the circumference of the central ventilation duct. A secondary air channel is formed between the outer surface of the primary air ducts and the inner wall of the outer duct. A sealing ring is installed on the outer surface of the primary air ducts. The sealing ring separates the secondary air channel from the primary air ducts. The secondary air channel is connected to the air inlet. Both the central ventilation duct and the primary air duct are connected to the coal powder airflow mixing inlet.

[0010] Preferably, the primary air duct has a gradually tapering tubular structure with one end being thicker than the other, and the thicker end is closer to the air inlet.

[0011] Preferably, the outer pipe is a tubular structure of equal diameter; the secondary air channel is a gradually changing tubular structure with one end narrower and the other end wider, and the narrower end is closer to the coal powder gas mixing inlet.

[0012] Preferably, the cross-section of the primary air duct has a gradually decreasing height structure.

[0013] The present invention also proposes a working method for a flexible peak-shaving burner as mentioned above. The specific method is as follows: when the load demand decreases, each baffle moves synchronously toward the central ventilation pipe along the radial direction of the central ventilation pipe to reduce the cross-sectional area of ​​the outer pipe, thereby reducing the flow rate of the pulverized coal mixed airflow.

[0014] When the load demand increases, each baffle moves synchronously away from the central ventilation duct along the radial direction of the central ventilation duct to increase the cross-sectional area of ​​the outer duct, thereby increasing the flow rate of the pulverized coal mixture.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The present invention sets several baffles in the radial direction of the central ventilation pipe. The baffles move along the radial direction of the central ventilation pipe to change the cross-sectional area of ​​the outer pipe. The outer pipe is then divided into two independent flow channels by the primary air pipe. The inner cavity of the primary air pipe and the central ventilation pipe jointly transport the mixed airflow of pulverized coal and air. The secondary air channel transports secondary air. By changing the position of the baffles, the flow rate of the pulverized coal mixed airflow is adjusted to meet the needs of the thermal power plant for balanced energy supply.

[0017] (2) The present invention uses a primary air duct with one end thick and the other end thin to transport the coal powder mixed airflow, so that the coal powder mixed airflow ejected from the end of the primary air duct and the coal powder mixed airflow ejected from the end of the central ventilation duct form a velocity difference, generating turbulence, eddies and other phenomena, thereby promoting more uniform mixing of coal powder mixed gas.

[0018] (3) The secondary air duct forms a gradually tapered tubular structure with one end being thin and the other end being thick. There is also a speed difference between the coal powder mixed airflow ejected from the end of the primary air duct and the air ejected from the end of the secondary air duct, which improves the mixing effect of the secondary air intake and the coal powder mixed airflow. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 This is a schematic diagram of the entire burner structure proposed in an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the entire burner from another perspective, as presented in an embodiment of the present invention.

[0022] Figure 3 This is a partial cross-sectional structural diagram of the burner proposed in an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the installation structure of the baffle in an embodiment of the present invention;

[0024] Figure 5 for Figure 4 Another perspective structural diagram of the middle section;

[0025] Figure 6 This is a schematic diagram of the central ventilation duct in an embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the installation structure of the sealing ring in an embodiment of the present invention;

[0027] Figure 8This is a schematic diagram of the installation structure of the primary air duct in an embodiment of the present invention;

[0028] Figure 9 This is a schematic diagram of the outer tube in an embodiment of the present invention.

[0029] In the diagram: 1. Central ventilation duct; 11. First extension duct; 12. Through hole;

[0030] 2. Outer tube; 21. Second extension tube; 22. Opening; 23. Inner folding plate; 24. Mounting base;

[0031] 3. Primary air duct; 31. Sealing ring;

[0032] 4. Secondary air duct; 5. Air inlet; 6. Pulverized coal airflow mixing inlet;

[0033] 7. Baffle; 71. Drive ring; 72. Arc-shaped drive groove; 73. Slider; 74. Fixing ring; 75. Limiting straight groove; 711. Gear ring; 712. Gear; 713. Servo motor; 714. Protective cover. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0035] Please see Figures 1-9 This embodiment proposes a flexible peak-shaving burner, comprising a central ventilation pipe 1 and an outer pipe 2 arranged sequentially from the inside out. The central ventilation pipe 1 is connected to a pulverized coal gas flow mixing inlet 6 to supply air to the combustion equipment, and the outer pipe 2 is connected to an air inlet 5 to supply fuel to the combustion equipment. In this embodiment, the fuel is a pulverized coal gas flow. The pulverized coal gas flow and air mix at the end of the central ventilation pipe 1, forming stable combustion in conjunction with an igniter. In practical applications, the operation of thermal power plants is adjusted according to the load demand of the power system to balance energy supply and demand and ensure the stable operation of the power system. For example, during the high load period of the day and the low load period of the night, by adjusting the supply of pulverized coal gas flow and air, the system load can be better matched to ensure the balance between supply and demand. Therefore, this invention arranges several baffles 7 in a ring array around the central ventilation pipe 1 on the circumferential surface of the outer pipe 2. As the load demand decreases, each baffle 7 moves synchronously toward the central ventilation pipe 1 along the radial direction, reducing the cross-sectional area of ​​the outer pipe 2.

[0036] Specifically, a drive ring 71 is movably fitted onto the circumferential surface of the outer tube 2. One end of the drive ring 71 has an arc-shaped drive groove 72 that penetrates the baffle 7. The number of arc-shaped drive grooves 72 is the same as the number of baffles 7. With the reference direction being the center closer to the center ventilation pipe 1 as the inside and the direction farther from the center ventilation pipe 1 as the outside, the arc-shaped drive groove 72 is inclined inward. A slider 73 is slidably connected inside the arc-shaped drive groove 72. The slider 73 is fixedly connected to the baffle 7. A fixing ring 74 is installed at one end of the drive ring 71. One end of the fixing ring 74 has a through-hole limiting straight groove 75. The limiting straight groove 75 is located on the extension line of the baffle 7, and the number of limiting straight grooves 75 is the same as the number of baffles 7. The baffle 7 is slidably assembled in the limiting straight groove 75. In this embodiment, taking the reduction in load demand as an example: the drive ring 71 rotates counterclockwise and squeezes the slider 73 through the arc-shaped drive groove 72, causing the slider 73 to move in a straight line along the limiting straight groove 75 towards the central ventilation pipe 1. The slider 73 drives the baffle 7 to move in a straight line towards the central ventilation pipe 1, and the baffle 7 forms a shield around the inner cavity of the outer pipe 2, reducing the cross-sectional area of ​​the outer pipe 2, thereby reducing the air supply. It should be noted that when the load demand decreases, the supply of pulverized coal airflow also decreases.

[0037] Based on the above scheme, the rotation of the drive ring 71 is driven by a servo motor 713. Specifically, a gear ring 711 is fixedly sleeved on the circumferential surface of the drive ring 71, and a gear 712 is meshed with the gear ring 711. The diameter of the gear 712 is smaller than the diameter of the gear ring 711, which plays a role in reducing speed and increasing output torque. The gear 712 is fixedly connected to the motor shaft of the servo motor 713, and the servo motor 713 is fixedly mounted on the circumferential surface of the outer tube 2. In this embodiment, the counterclockwise rotation of the drive ring 71 is taken as an example: the servo motor 713 is started, the motor shaft of the servo motor 713 drives the gear 712 to rotate counterclockwise, and the gear 712 drives the gear ring 711 to rotate, thereby realizing the counterclockwise rotation of the drive ring 71.

[0038] In addition, it can improve the gas mixing effect of the burner, making the combustion more complete. Secondary air is generally introduced into the burner. On the one hand, by adjusting the amount of secondary air, the combustion process can be better controlled, reducing flame fluctuations and oscillations, and improving the stability of the system. On the other hand, introducing an appropriate amount of secondary air can cool the combustion zone, thereby reducing the combustion temperature. This helps to slow down the oxidation rate of the fuel and reduce the generation of harmful substances such as nitrogen oxides that are easily generated at high temperatures. Therefore, in this invention, several primary air pipes 3 are installed between the central ventilation pipe 1 and the outer pipe 2. The internal cavity of the primary air pipes 3 works together with the central ventilation pipe 1 to transport a mixed airflow of pulverized coal and air. A secondary air channel 4 is formed between the several primary air pipes 3 and the central ventilation pipe 1. Air is transported through the secondary air channel 4 to form secondary air intake.

[0039] Specifically, several primary air ducts 3 are evenly installed on the circumference of the central ventilation duct 1. A secondary air channel 4 is formed between the outer surface of the primary air ducts 3 and the inner wall of the outer duct 2. A sealing ring 31 is installed on the outer surface of the primary air ducts 3. The sealing ring 31 separates the secondary air channel 4 and the primary air ducts 3. The secondary air channel 4 is connected to the air inlet 5. Both the central ventilation duct 1 and the primary air ducts 3 are connected to the coal powder airflow mixing inlet 6.

[0040] Inside the coal powder gas mixing inlet 6, the coal powder gas and air undergo the first mixing. In order to improve the mixing effect of the coal powder mixed gas and the secondary air intake gas, the primary air duct 3 is designed as a gradually tapered tubular structure with one end thicker than the other, and the thicker end is close to the air inlet 5. The flow velocity of the coal powder mixed gas through the primary air duct 3 and the end of the central ventilation duct 1 is different. When the high-velocity airflow meets the low-velocity airflow, turbulence, eddies and other phenomena will be generated, thereby promoting a more uniform mixing of the coal powder mixed gas.

[0041] Similarly, since the outer pipe 2 is a tubular structure of equal diameter, the secondary air channel 4 also forms a gradually changing tubular structure with one end narrow and the other end wide. The narrower end is close to the coal powder airflow mixing inlet 6. There is also a speed difference between the coal powder mixed airflow ejected from the end of the primary air pipe 3 and the air ejected from the end of the secondary air channel 4, which improves the mixing effect of the secondary air intake and the coal powder mixed airflow.

[0042] Based on the above scheme, in this embodiment, the cross-section of the primary air duct 3 is designed as a gradually decreasing structure. When the coal powder mixed airflow is at different positions in the primary air duct 3, different velocities will be formed, thereby forming a velocity gradient inside the primary air duct 3, increasing the probability of turbulence and eddies, so that the coal powder mixed airflow is fully mixed in the primary air duct 3, further improving the mixing quality of coal powder and air.

[0043] In addition, the primary air duct 3 can be designed as a spiral tubular structure, so that the coal powder airflow ejected from the end of the primary air duct 3 and the coal powder mixed airflow ejected from the end of the central ventilation duct 1 form an angle difference, increasing the probability of forming a cyclone in the area at the end of the central ventilation duct 1 and improving the mixing effect of the coal powder mixed airflow and air.

[0044] In order to increase the air content in the end area of ​​the central ventilation pipe 1, in this embodiment, a first extension pipe 11 is installed at the end of the central ventilation pipe 1, and through holes 12 are evenly opened on the circumferential surface of the first extension pipe 11; a second extension pipe 21 is installed at the end of the outer pipe 2, and several openings 22 are opened on the circumferential surface of the second extension pipe 21. An inner folding plate 23 inclined towards the central ventilation pipe 1 is installed in the opening 22. The flow area of ​​the airflow is increased by the inner folding plate 23 and the through holes 12, thereby improving the mixing effect of pulverized coal airflow and air.

[0045] To facilitate the installation of the burner, in this embodiment, a mounting base 24 is fixedly sleeved on the circumferential surface of the outer tube 2, and the entire device is fixedly installed on the mounting surface by the mounting base 24.

[0046] Furthermore, this embodiment also proposes a flexible peak-shaving burner operation method, including the following:

[0047] When the load demand decreases, each baffle 7 moves synchronously toward the central ventilation pipe 1 along the radial direction of the central ventilation pipe 1, reducing the cross-sectional area of ​​the outer pipe 2, thereby reducing the flow rate of the pulverized coal mixed airflow.

[0048] When the load demand increases, each baffle 7 moves synchronously away from the central ventilation pipe 1 along the radial direction of the central ventilation pipe 1, increasing the cross-sectional area of ​​the outer pipe 2, thereby increasing the flow rate of the pulverized coal mixed airflow.

[0049] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A flexible peak-shaving burner, comprising a central ventilation pipe (1) and an outer pipe (2) arranged sequentially from the inside to the outside, the central ventilation pipe (1) being connected to a pulverized coal gas flow mixing inlet (6) to supply fuel to the combustion equipment, and the outer pipe (2) being connected to an air inlet (5) to supply air to the combustion equipment, characterized in that: The outer tube (2) has several baffles (7) arranged in a ring array around the central ventilation tube (1). Each baffle (7) can move synchronously towards or away from the central ventilation tube (1) along the radial direction of the central ventilation tube (1). Several primary air ducts (3) are evenly installed on the circumference of the central ventilation duct (1), and a secondary air channel (4) is formed between the outer surface of the several primary air ducts (3) and the inner wall of the outer duct (2). A sealing ring (31) is installed on the outer surface of several primary air ducts (3). The secondary air duct (4) and the primary air duct (3) are separated by the sealing ring (31). The secondary air duct (4) is connected to the air inlet (5). The central ventilation duct (1) and the primary air duct (3) are both connected to the coal powder airflow mixing inlet (6). The primary air duct (3) has a gradually tapered tubular structure with one end being thicker than the other, and the thicker end is closer to the air inlet (5). The outer pipe (2) is a tubular structure of equal diameter; the secondary air channel (4) is a gradually changing tubular structure with one end thin and the other end thick, and the thinner end is close to the coal powder airflow mixing inlet (6). The cross-section of the primary air duct (3) has a gradually decreasing height structure.

2. The flexible peak-shaving burner according to claim 1, characterized in that: The outer tube (2) is movably fitted with a drive ring (71). One end of the drive ring (71) is provided with an arc-shaped drive groove (72) that penetrates the baffle (7). The number of arc-shaped drive grooves (72) is the same as the number of baffles (7). With the center of the central ventilation pipe (1) as the inside and the center of the central ventilation pipe (1) as the outside, the arc-shaped drive grooves (72) are inclined inward. A slider (73) is slidably connected inside the arc-shaped drive groove (72), and the slider (73) is fixedly connected to the baffle (7); A fixed ring (74) is installed at one end of the drive ring (71). A through-hole limiting straight groove (75) is opened at one end of the fixed ring (74). The limiting straight groove (75) is located on the extension line of the baffle (7), and the number of limiting straight grooves (75) is the same as the number of baffles (7). The baffles (7) are slidably assembled in the limiting straight groove (75).

3. The flexible peak-shaving burner according to claim 2, characterized in that: A gear ring (711) is fixedly sleeved on the circumferential surface of the drive ring (71), and a gear (712) is meshed with the gear ring (711). The diameter of the gear (712) is smaller than the diameter of the gear ring (711), and the gear (712) is fixedly connected to the motor shaft of the servo motor (713) which is fixedly installed on the circumferential surface of the outer tube (2).

4. A method for operating a flexible peak-shaving burner as described in claim 1, characterized in that: When the load demand decreases, each baffle (7) moves synchronously toward the central ventilation pipe (1) along the radial direction of the central ventilation pipe (1) to reduce the cross-sectional area of ​​the outer pipe (2), thereby reducing the flow rate of the coal powder mixed airflow. When the load demand increases, each baffle (7) moves synchronously away from the central ventilation pipe (1) along the radial direction of the central ventilation pipe (1) to increase the cross-sectional area of ​​the outer pipe (2), thereby increasing the flow rate of the coal powder mixed airflow.

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