A method and apparatus for reducing the carbon content of fly ash from coal-fired power plants

Abstract

This invention discloses a method and apparatus for reducing the carbon content of fly ash from coal-fired power plants. The apparatus includes a coal-fired furnace and multiple layers of burners arranged equidistantly from top to bottom inside the furnace. Each layer of burners has a corresponding coal conveying pipe connected to its input end, and the input end of the coal conveying pipe is connected to a ball mill. A coal powder fineness detection device is installed on the coal conveying pipe, and the coal powder fineness detection device is electrically connected to a controller. The apparatus provided by this invention controls the change in coal powder particle size by controlling the number of steel balls, and ensures that each layer of burners corresponds to a ball mill, thereby separately regulating the coal powder particle size in each layer of burners. Furthermore, based on the different positions of each layer of burners and the differences in the combustion flight time of the coal powder, combined with actual detection results, the size of the coal powder particles is adjusted to meet the optimal combustion condition range, so as to achieve complete combustion and reduce the carbon content of fly ash as much as possible.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, and specifically to a method and apparatus for reducing the carbon content of fly ash from coal-fired power plants. Background Technology

[0002] The combustible material in fly ash from coal-fired power plant boilers is mainly unburned carbon particles. The carbon content of fly ash in coal-fired power plants is a key indicator for measuring coal burnout, which is crucial for improving coal utilization and is related to boiler operation safety. Boilers generally include multiple layers of burners, each of which delivers pulverized coal. Studies have shown that the carbon content of boiler fly ash is related not only to the type of coal used, but also to the boiler structure and the fineness of the pulverized coal. Increasing the residence time of pulverized coal inside the boiler is beneficial for the burnout of pulverized coal particles and the reduction of carbon content in fly ash.

[0003] To address the aforementioned issues, existing boilers typically employ in-furnace combustion adjustment methods to reduce fly ash carbon content. The conventional approach involves adjusting the fineness of the pulverized coal. However, for multi-layer burners in boilers, while the fineness adjustment is the same for each burner layer, the residence time of pulverized coal within the boiler furnace varies across layers. Using the same fineness adjustment for each burner layer can easily lead to incomplete combustion of the upper layers of pulverized coal, resulting in higher carbon content in the fly ash.

[0004] Therefore, existing methods for reducing the carbon content of fly ash in combustion furnaces are not very effective. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for reducing the carbon content of fly ash from coal-fired power plants, thereby solving the technical problem in the prior art that the fineness of pulverization cannot be adjusted according to the different positions of the burners in the boiler.

[0006] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0007] In a first aspect of the invention, an apparatus for reducing the carbon content of fly ash from a coal-fired power plant is provided, comprising a coal-fired furnace and multiple layers of burners arranged at equal intervals from top to bottom inside the coal-fired furnace. Each layer of burners has a corresponding coal conveying pipe connected to its input end. The input end of the coal conveying pipe is connected to a ball mill. A coal powder fineness detection device is provided on the coal conveying pipe. The coal powder fineness detection device is electrically connected to a controller. The ball mill contains multiple steel balls, and a gripping structure for gripping and releasing the steel balls is provided on the ball mill. The gripping structure is electrically connected to the controller.

[0008] The controller adjusts the gripping structure to grip or release steel balls based on the coal powder particle size value detected by the coal powder fineness detection device on each burner layer, thereby controlling the ball milling particle size of the corresponding coal powder in the ball mill and adjusting the coal powder particle size in each burner layer respectively.

[0009] Furthermore, the ball mill includes a casing, and a slot for throwing steel balls is formed on the outer surface of the casing. The gripping structure includes a fixed frame disposed outside the slot and fixedly connected to the casing, and a clamping plate that engages with the slot. A first power mechanism is fixedly connected between the clamping plate and the fixed frame. The first power mechanism controls the clamping plate to move closer to or away from the slot. The portion of the casing covered by the fixed frame is a support plate. A push plate is provided on the side of the support plate near the fixed frame. A second power mechanism is fixedly connected between the push plate and the fixed frame.

[0010] The centrifugal force generated when the casing rotates causes the steel balls to travel along the inner wall of the casing through the slots to the outer side of the support plate, thereby reducing the number of steel balls inside the casing. The pusher plate then pushes the steel balls on the outer side of the support plate back into the casing, thereby increasing the number of steel balls inside the casing.

[0011] Furthermore, the steel ball has at least two sizes, and the groove width is greater than the diameter of the smaller steel ball and less than the diameter of the larger steel ball.

[0012] Furthermore, a 7-shaped baffle is fixedly connected to the side of the card plate away from the machine housing. The end of the baffle away from the card plate is in contact with the fixed frame. When the card plate is engaged with the card slot, the baffle and the push plate are in contact with the end away from the machine housing, so that the baffle, the push plate and the support plate together form a space to accommodate the steel ball after it is grasped.

[0013] Furthermore, the support plate has multiple mesh holes, allowing coal dust thrown out from the slot to leak out through the mesh holes.

[0014] Furthermore, a filter screen is fixedly connected to one end of the push plate near the support plate. The filter screen is laid along the outer surface of the support plate, so that the end of the filter screen away from the push plate is fixedly connected to the end of the support plate. The filter screen can be rolled up under the action of external force. When the steel ball is thrown out from the slot, it falls on the filter screen. The movement of the push plate causes the filter screen to roll up, so that the steel ball is squeezed out and returns to the inside of the casing from the slot.

[0015] Furthermore, the ball mill input end is equipped with multi-stage screens, so that the coal powder raw materials are screened by the screens and then enter the corresponding ball mills.

[0016] In a second aspect of the invention, a method for reducing the carbon content of fly ash from coal-fired power plants is provided, employing the aforementioned apparatus for reducing the carbon content of fly ash from large coal-fired power plants, comprising the following steps:

[0017] Based on the height of each burner layer, the pulverized coal combustion flight time of each burner layer is calculated to obtain the theoretical value of the required pulverized coal particle size for each burner layer.

[0018] The actual particle size of the pulverized coal in each burner layer is measured using a pulverized coal fineness testing device.

[0019] The particle size of pulverized coal is automatically controlled and adjusted for each layer of burner based on the difference between the actual and theoretical values, so that the actual particle size of each layer of pulverized coal is infinitely close to the theoretical value.

[0020] Furthermore, by adjusting the number of steel balls inside the ball mill, the particle size of the pulverized coal in each layer of the burner is adjusted, so that the actual value of the particle size of each layer of pulverized coal is infinitely close to the theoretical value, and the particle size of the pulverized coal in the multi-layer burner decreases from bottom to top.

[0021] Furthermore, the ball mill has at least two sizes of steel balls, and the particle size of the coal powder inside the ball mill can be controlled by increasing or decreasing the number of smaller steel balls.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The device provided by this invention controls the change in coal powder particle size by controlling the number of steel balls, and makes each layer of burners correspond to a ball mill to adjust the coal powder particle size in each layer of burners. Then, based on the different positions of each layer of burners and the differences in the combustion flight time of coal powder, and combined with actual detection results, the size of coal powder particles is adjusted to meet the optimal combustion conditions range, so as to achieve complete combustion as much as possible and reduce the carbon content of fly ash. In addition, in this invention, differentiated grinding is used to meet the different requirements of different burners for coal powder fineness, so as to achieve the purpose of automated differential control of the combustion process.

[0024] 2. The method provided by this invention calculates the pulverized coal combustion flight time based on the position of different burners, and automatically controls the particle size of the coal milling equipment based on the detection results of the pulverized coal fineness detection device. Since the fineness of each layer of burners is adjusted separately, the pulverized coal particles of each layer correspond to the combustion flight time of that layer of pulverized coal, so that the pulverized coal is completely burned in the furnace, especially the upper layer of pulverized coal, thereby reducing the carbon content of the fly ash of the entire coal-fired power plant. Attached Figure Description

[0025] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the coal-fired furnace provided by the present invention;

[0027] Figure 2 This is a cross-sectional view of the ball mill of the present invention;

[0028] Figure 3 For the present invention Figure 2 Enlarged view of the structure of section A in the middle;

[0029] Figure 4 This is a schematic diagram of the structure when the internal clamping plate and the clamping slot of the ball mill are separated in this invention.

[0030] The labels in the diagram represent the following:

[0031] 10-Coal-fired furnace; 20-Burner; 30-Coal conveying pipe; 40-Ball mill; 50-Controller; 60-Grabbing structure; 70-Screen;

[0032] 31-Pulverized coal fineness detection device;

[0033] 41-Steel ball; 42-Casing; 43-Slot; 44-Support plate; 45-Mesh;

[0034] 61-Fixed frame; 62-Clamping plate; 63-First power mechanism; 64-Push plate; 65-Second power mechanism; 66-Baffle; 67-Placement space; 68-Filter screen. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figure 1 and Figure 2 As shown, the present invention provides a device for reducing the carbon content of fly ash from coal-fired power plants, which mainly reduces the carbon content of fly ash by separately adjusting the particle size of coal powder in different layers of burners 20.

[0037] The system includes a coal-fired furnace 10 and multiple layers of burners 20 arranged at equal intervals from top to bottom inside the coal-fired furnace 10. Each layer of burners 20 has a corresponding coal conveying pipe 30 connected to its input end. The input end of the coal conveying pipe 30 is connected to a ball mill 40. A coal powder fineness detection device 31 is provided on the coal conveying pipe 30. The coal powder fineness detection device 31 is electrically connected to a controller 50. The ball mill 40 contains multiple steel balls 41 and a gripping structure 60 for gripping and releasing the steel balls 41 is provided on the ball mill 40. The gripping structure 60 is electrically connected to the controller 50.

[0038] The controller 50 adjusts the gripping structure 60 to grip or release steel balls 41 based on the coal powder particle size value detected by the coal powder fineness detection device 31 on each burner 20, thereby controlling the ball milling particle size of the coal powder in the corresponding ball mill 40 and adjusting the coal powder particle size in each burner 20 respectively.

[0039] In existing conventional boilers, the pulverization fineness adjustment is the same for each layer of burners 20. Since the residence time of pulverized coal in the boiler furnace is different for each layer of burners 20, if the same pulverization fineness adjustment is used for each layer of burners 20, it is easy to cause incomplete combustion of the upper layer of pulverized coal, with a small amount not being completely burned, resulting in a high carbon content in fly ash and a low overall coal utilization rate. Therefore, it is necessary to develop a device to reduce the carbon content of fly ash in large coal-fired power plants.

[0040] There are many methods to reduce the carbon content of fly ash, including adjusting the fineness of the pulverized coal. However, this only involves adjusting multiple burners 20 simultaneously within the same range. According to the inventor's research, the residence time of pulverized coal in the boiler furnace of each layer of burners 20 is different, which leads to different combustion completeness rates of pulverized coal in each layer of burners 20. This is a point that has been overlooked by people in the field. It is difficult to think of using the height difference between each layer of burners 20 to adjust the particle size of pulverized coal separately.

[0041] This embodiment controls the change in pulverized coal particle size by controlling the number of steel balls 41, and ensures that each layer of burner 20 corresponds to a ball mill 40, thereby adjusting the pulverized coal particle size in each layer of burner 20. Furthermore, based on the different positions of each layer of burner 20 and the differences in pulverized coal combustion flight time, combined with actual test results, the size of the pulverized coal particles is adjusted to meet the optimal combustion condition range, so as to achieve complete combustion as much as possible and reduce the carbon content of fly ash. In addition, in this invention, differentiated grinding is used to meet the different requirements of different burners 20 for pulverized coal fineness, so as to achieve the purpose of automated differential control of the combustion process.

[0042] In practical use:

[0043] 1. Each layer of burners 20 corresponds to one coal conveying pipe 30 and one ball mill 40;

[0044] 2. The coal powder fineness detection device 31 detects the particle size of the coal powder input into each layer of burner 20 in real time;

[0045] 3. By using the difference between the actual and theoretical coal powder particle size in each burner 20, the number of steel balls 41 in the corresponding ball mill 40 is adjusted by the gripping structure 60, thereby controlling the particle size of coal powder in each burner 20.

[0046] Furthermore, such as Figure 3 and Figure 4 As shown, the ball mill 40 includes a housing 42. A slot 43 for throwing steel balls 41 is provided on the outer surface of the housing 42. The gripping structure 60 includes a fixed frame 61 disposed outside the slot 43 and fixedly connected to the housing 42, and a clamping plate 62 that engages with the slot 43. A first power mechanism 63 is fixedly connected between the clamping plate 62 and the fixed frame 61. The first power mechanism 63 controls the clamping plate 62 to move closer to or away from the slot 43. The part of the housing 42 covered by the fixed frame 61 is a support plate 44. A push plate 64 is provided on the side of the support plate 44 near the fixed frame 61. A second power mechanism 65 is fixedly connected between the push plate 64 and the fixed frame 61.

[0047] The centrifugal force of the rotating housing 42 causes the steel balls 41 to travel along the inner wall of the housing 42 through the slot 43 to the outer side of the support plate 44, thereby reducing the number of steel balls 41 inside the housing 42. The pusher plate 64 pushes the steel balls 41 on the outer side of the support plate 44 back into the housing 42, thereby increasing the number of steel balls 41 inside the housing 42.

[0048] A 7-shaped baffle 66 is fixedly connected to the side of the card plate 62 away from the housing 42. The end of the baffle 66 away from the card plate 62 is in contact with the fixed frame 61. When the card plate 62 is engaged with the card slot 43, the baffle 66 and the push plate 64 are in contact with the end away from the housing 42, so that the baffle 66, the push plate 64 and the support plate 44 together form a placement space 67 for accommodating the steel ball 41 after it is grasped.

[0049] The first power mechanism 63 and the second power mechanism 65 are preferably hydraulic rods or telescopic rods.

[0050] During use, as the housing 42 rotates, the steel ball 41 also rotates. When the coal powder particle size in the burner 20 is small, some of the steel balls 41 need to be removed. When the fixing frame 61 rotates to the top of the housing 42, the first power mechanism 63 drives the card plate 62 to move upward, so that the card slot 43 is opened. Then, due to centrifugal force, the steel ball 41 moves from the card slot 43 to the placement space 67. As the housing 42 rotates, when the fixing frame 61 rotates to the bottom of the housing 42, the card plate 62 engages with the card slot 43, allowing the removed steel ball 41 to return to the inside of the housing 42.

[0051] When the coal powder particle size in the burner 20 is large, some steel balls 41 need to be added. When the fixed frame 61 rotates to the top of the housing 42, the first power mechanism 63 drives the card plate 62 to move upward, so that the card slot 43 is opened. At this time, the second power mechanism 65 drives the push plate 64 to move, which pushes the steel balls 41 in the placement space 67 into the housing 42. Then the card plate 62 is returned to its original position.

[0052] Furthermore, in order to enhance the effectiveness of regulation, such as Figure 2 As shown, the steel ball 41 has at least two sizes. The width of the slot 43 is greater than the diameter of the smaller steel ball 41 and smaller than the diameter of the larger steel ball 41. As the housing 42 rotates, the smaller steel ball 41 can be thrown out through the slot 43, while the larger steel ball 41 cannot be thrown out. The more small steel balls 41 there are, the smaller the coal powder particle size will be.

[0053] When the steel ball 41 is thrown and reaches the placement space 67, coal dust will also be thrown out. Therefore, the support plate 44 has multiple mesh holes 45, so that the coal dust thrown out from the slot 43 can leak out through the mesh holes 45. The steel ball 41 is trapped by the mesh holes 45, while the coal dust is leaked out.

[0054] To facilitate the ejection of the steel ball 41, a filter screen 68 is fixedly connected to one end of the push plate 64 near the support plate 44. The filter screen 68 is laid along the outer surface of the support plate 44, so that the end of the filter screen 68 away from the push plate 64 is fixedly connected to the end of the support plate 44. The filter screen 68 can be rolled up under the action of external force. When the steel ball 41 is thrown out from the slot 43, it falls on the filter screen 68. The movement of the push plate 64 causes the filter screen 68 to roll up, so that the steel ball 41 is squeezed out and returns to the inside of the housing 42 from the slot 43.

[0055] The ball mill 40 is equipped with a multi-stage screen 70 at its input end, so that the coal powder raw material is screened by the screen 70 and then enters the corresponding ball mill 40.

[0056] The following method for reducing the carbon content of fly ash from coal-fired power plants, in conjunction with the aforementioned device for reducing the carbon content of fly ash from large coal-fired power plants, includes the following steps:

[0057] Based on the height position of each layer of burners 20, the pulverized coal combustion flight time of each layer of burners 20 is calculated, and the theoretical value of the required pulverized coal particle size for each layer of burners 20 is obtained.

[0058] The actual value of the actual pulverized coal particle size in each burner 20 is detected by the pulverized coal fineness detection device 31.

[0059] Based on the difference between the actual and theoretical values ​​of pulverized coal particle size, the particle size of pulverized coal in each burner layer is automatically controlled and adjusted to make the actual value of pulverized coal particle size in each layer infinitely close to the theoretical value.

[0060] The particle size of pulverized coal in each layer of burner 20 is adjusted by controlling the number of steel balls 41 inside the ball mill 40, so that the actual value of the particle size of each layer of pulverized coal is infinitely close to the theoretical value, and the particle size of pulverized coal in the multi-layer burner 20 decreases from bottom to top.

[0061] The steel balls 41 inside the ball mill 40 have at least two sizes, and the particle size of the coal powder inside the ball mill 40 can be adjusted by increasing or decreasing the number of smaller steel balls 41 inside the ball mill 40.

[0062] The method provided by this invention calculates the pulverized coal combustion flight time based on the position of different burners 20, and automatically controls the particle size of the coal milling equipment based on the detection results of the pulverized coal fineness detection device 31. Since the fineness of each layer of burners 20 is adjusted, the pulverized coal particles of each layer correspond to the combustion flight time of that layer of pulverized coal, so that the pulverized coal is completely burned in the furnace, especially the upper layer of pulverized coal, thereby reducing the carbon content of fly ash in the entire coal-fired power plant.

[0063] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A device for reducing the carbon content of fly ash from coal-fired power plants, characterized in that, The device includes a coal-fired furnace (10) and multiple layers of burners (20) arranged at equal intervals from top to bottom inside the coal-fired furnace (10). Each layer of burners (20) has a corresponding coal conveying pipe (30) connected to its input end. The input end of the coal conveying pipe (30) is connected to a ball mill (40). A coal powder fineness detection device (31) is provided on the coal conveying pipe (30). The coal powder fineness detection device (31) is electrically connected to a controller (50). The ball mill (40) contains multiple steel balls (41) and a gripping structure (60) is provided on the ball mill (40) for gripping and releasing the steel balls (41). The gripping structure (60) is electrically connected to the controller (50). The controller (50) adjusts the gripping structure (60) to grip or release steel balls (41) according to the coal powder particle size value detected by the coal powder fineness detection device (31) on each burner (20) to control the ball milling particle size of the corresponding ball mill (40), thereby adjusting the coal powder particle size in each burner (20). The ball mill (40) includes a housing (42), and a slot (43) for throwing steel balls (41) is provided on the outer surface of the housing (42). The gripping structure (60) includes a fixed frame (61) disposed outside the slot (43) and fixedly connected to the housing (42) and a clamping plate (62) that engages with the slot (43). A first power mechanism (63) is fixedly connected between the clamping plate (62) and the fixed frame (61). The clamping plate (62) is controlled to move closer to or away from the slot (43) by the first power mechanism (63). The part of the housing (42) covered by the fixed frame (61) is a support plate (44). A push plate (64) is provided on the side of the support plate (44) close to the fixed frame (61). A second power mechanism (65) is fixedly connected between the push plate (64) and the fixed frame (61). The centrifugal force of the rotating housing (42) causes the steel balls (41) to travel along the inner wall of the housing (42) through the slot (43) to the outer side of the support plate (44), thereby reducing the number of steel balls (41) inside the housing (42). The push plate (64) pushes the steel balls (41) on the outer side of the support plate (44) back into the housing (42), thereby increasing the number of steel balls (41) inside the housing (42). A 7-shaped baffle (66) is fixedly connected to the side of the card plate (62) away from the housing (42). The end of the baffle (66) away from the card plate (62) is in contact with the fixed frame (61). When the card plate (62) is engaged with the card slot (43), the baffle (66) and the push plate (64) are in contact with the end away from the housing (42), so that the baffle (66), the push plate (64) and the support plate (44) together form a placement space (67) for accommodating the steel ball (41) after it is grasped.

2. The device for reducing the carbon content of fly ash from coal-fired power plants according to claim 1, characterized in that, The steel ball (41) has at least two sizes, and the width of the slot (43) is greater than the diameter of the smaller steel ball (41) and less than the diameter of the larger steel ball (41).

3. The device for reducing the carbon content of fly ash from coal-fired power plants according to claim 1, characterized in that, The support plate (44) has multiple mesh holes (45) so that the coal powder thrown out from the slot (43) can leak out through the mesh holes (45).

4. The device for reducing the carbon content of fly ash from coal-fired power plants according to claim 3, characterized in that, A filter screen (68) is fixedly connected to one end of the push plate (64) near the support plate (44). The filter screen (68) is laid along the outer surface of the support plate (44), so that the end of the filter screen (68) away from the push plate (64) is fixedly connected to the end of the support plate (44). The filter screen (68) can be rolled up under the action of external force. When the steel ball (41) is thrown out from the slot (43), it falls on the filter screen (68). The movement of the push plate (64) causes the filter screen (68) to roll up, so that the steel ball (41) is squeezed out and returns to the inside of the casing (42) from the slot (43).

5. The device for reducing the carbon content of fly ash from coal-fired power plants according to claim 4, characterized in that, The ball mill (40) is equipped with a multi-stage screen (70) at the input end, so that the coal powder raw material is screened by the screen (70) and then enters the corresponding ball mill (40).

6. A method for reducing the carbon content of fly ash from coal-fired power plants, characterized in that, The device for reducing the carbon content of fly ash from coal-fired power plants as described in any one of claims 1-5 is used. Includes the following steps: Based on the height position of each burner (20), the pulverized coal combustion flight time of each burner (20) is calculated, and the theoretical value of the required pulverized coal particle size for each burner (20) is obtained. The actual value of the actual coal powder particle size of each burner (20) is detected by the coal powder fineness detection device (31); The particle size of each layer of burner (20) is automatically controlled and adjusted according to the difference between the actual value and the theoretical value of the pulverized coal particle size, so that the actual value of the pulverized coal particle size of each layer is infinitely close to the theoretical value.

7. A method for reducing the carbon content of fly ash from coal-fired power plants according to claim 6, characterized in that, The particle size of coal powder in each layer of burner (20) is adjusted by controlling the number of steel balls (41) inside the ball mill (40), so that the actual value of the particle size of coal powder in each layer is infinitely close to the theoretical value, and the particle size of coal powder in the multi-layer burner (20) decreases from bottom to top.

8. A method for reducing the carbon content of fly ash from coal-fired power plants according to claim 7, characterized in that, The ball mill (40) has at least two sizes of steel balls (41) inside, and the particle size of coal powder inside the ball mill (40) is controlled by increasing or decreasing the number of smaller steel balls (41) inside the ball mill (40).

Images