A wide load coal-fired unit boiler post-dust removal system

Abstract

The utility model discloses a kind of wide load coal-fired unit furnace rear dust removal systems, including sequentially arranged main flue, several sub flues, electric dust collector group and several sub flues and main flue, the electric dust collector group is composed of several electric precipitators, each electric precipitator is equipped with several dust removal chambers, each dust removal chamber is equipped with dust inlet and dust outlet, dust inlet is connected with main flue by sub flue, dust outlet is connected with main flue by sub flue, electric damper is equipped in the sub flue and sub flue, smoke gas temperature changer is installed between sub flue and dust inlet;The utility model is divided into independent electric dust removal chamber by partition wall by electric precipitator, close and enable corresponding electric dust removal chamber by cooperating automatic control system, so that existing coal-fired unit can be accurately controlled when low load, dust outlet concentration, reduce energy consumption, adapt to low load of flue gas volume reduction, avoid the corrosion problem caused by local flow rate too low in electric precipitator interior.

Description

Technical Field

[0001] This utility model relates to the technical field of electrostatic precipitators, and in particular to the technical field of dust removal systems after the furnace of wide-load coal-fired power units. Background Technology

[0002] The new generation of coal-fired power units requires that the coal consumption of newly built units under low load power supply should not increase by more than 20% compared with the rated load, and the demonstration units should not exceed 15%. Therefore, reducing power consumption of electrostatic precipitators under low load is one of the key focuses of the new generation of coal-fired power units.

[0003] When large coal-fired power units operate at ultra-low loads of 15%-20%, the following problems mainly arise: (1) The amount of flue gas decreases, while the unit energy consumption and material consumption increase; (2) As the flue gas temperature decreases, the ash viscosity increases, leading to ash accumulation. (3) The amount of flue gas is reduced under low load, the airflow velocity is too low, and there is a problem of local ash accumulation.

[0004] Patent document CN114082530A discloses an electrostatic precipitator for use under varying loads. The device disclosed is a two-unit, three-chamber electrostatic precipitator. In actual operation, the device lacks targeted control measures under wide load conditions, making it difficult to effectively meet the operating requirements under low load conditions. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the prior art by proposing a dust removal system after the furnace of a wide-load coal-fired unit, which can solve the above problems.

[0006] To achieve the above objectives, this utility model proposes a wide-load coal-fired unit post-furnace dust removal system, comprising a main flue gas inlet, several branch flue gas inlets, an electric dust collector group, several branch flue gas outlets, and a main flue gas outlet, arranged sequentially. The electric dust collector group consists of several electric dust collectors, each of which has several dust collection chambers. Each dust collection chamber has a dust inlet and a dust outlet. The dust inlet is connected to the main flue gas inlet through a branch flue gas inlet, and the dust outlet is connected to the main flue gas outlet through a branch flue gas outlet. Both the branch flue gas inlets and the branch flue gas outlets are equipped with electric dampers, and a flue gas temperature converter is installed between the branch flue gas inlets and the dust inlets.

[0007] Flue gas temperature converters can raise the flue gas temperature to a safe range by heating (such as using waste heat or auxiliary heat sources); while under high load and when the flue gas temperature is too high, cooling (such as heat exchange devices) can be used to prevent the equipment from overheating and being damaged.

[0008] Preferably, the two ends of the flue gas inlet are provided with arc-shaped sections, and arc-shaped flue gas guide plates are provided in the arc-shaped sections. The surface of the flue gas guide plates is provided with a wear-resistant metal coating.

[0009] Preferably, the electric damper includes several dampers, which are rotatably mounted in the mounting frame via a rotating shaft. A rocker arm is mounted on the rotating shaft, and the rocker arm is connected to the linkage shaft.

[0010] Preferably, the linkage shaft consists of alternating mounting rods and adjusting sleeves. The rocker arm is rotatably mounted to the mounting rods via pins. The mounting rods have mounting grooves at both ends, and mounting nuts are provided at the openings of the mounting grooves. The adjusting sleeves have threaded posts threaded onto both ends, and the ends of the threaded posts are threaded onto the mounting nuts.

[0011] Preferably, the damper has a spindle-shaped cross-section that is larger in the middle and smaller at both ends. The damper has extension plates at both ends, and the extension plates of the damper abut against each other. The windward surface of the damper is provided with a wear-resistant lining.

[0012] Preferably, the damper includes a windward plate and a leeward plate that are centrally symmetrical. The windward plate and the leeward plate are arranged on both sides of the rotating shaft. One end of the windward plate protrudes from one end of the leeward plate, and the other end of the leeward plate protrudes from the other end of the windward plate.

[0013] Preferably, the electric dust collector assembly includes two electric dust collectors, each with four dust collection chambers, and each pair of adjacent dust collection chambers are separated by a partition wall.

[0014] Preferably, the electric dust collector group includes two electric dust collectors, each of which has three dust collection chambers, and adjacent dust collection chambers are separated by partition walls.

[0015] Preferably, the electric dust collector group includes three electric dust collectors. There are two main flue ducts, namely the first main flue duct and the second main flue duct. Each electric dust collector has two dust collection chambers, which are separated by a partition wall. The two dust collection chambers of the electric dust collector located in the middle are respectively connected to the middle branch flue ducts. One of the middle branch flue ducts is connected to the first main flue duct, and the other middle branch flue duct is connected to the second main flue duct.

[0016] The beneficial effects of this utility model are: This utility model divides the electrostatic precipitator into independent electrostatic precipitator chambers by using partition walls. With the help of an automatic control system, the corresponding electrostatic precipitator chambers can be closed and opened, so that the dust outlet concentration of the existing coal-fired unit can be accurately controlled at low load, reducing energy consumption, adapting to low load with reduced flue gas volume, and avoiding corrosion problems caused by localized drop in flue gas temperature due to excessively low local flow velocity inside the electrostatic precipitator. This utility model can achieve multi-load adaptability modification by modifying the damper, rapping control system and power control system of the existing electrostatic precipitator, meet the needs of boiler operation under multi-load conditions, reduce plant power consumption, has good adaptability to modification, and significantly reduces operating energy consumption at low load. This invention closes the electric damper of the flue gas passage that needs to be vibrated, and simultaneously stops or reduces the power supply to the electric field in the flue gas passage. It also prevents a significant increase in the flue gas flow in adjacent passages and reduces secondary dust through airflow adjustment measures. The shuttle-shaped streamlined structure of the damper has the advantages of high rigidity, small deformation, and low flow resistance. The rocker arm and the linkage shaft are connected by a pin. The linkage shaft is assembled by a mounting rod and an adjusting sleeve. The installation length can be adjusted by the threaded structure to achieve synchronous movement of the rocker arm. It allows for convenient inspection, adjustment, maintenance, and replacement of spare parts without the need for welding. This invention uses a wide-load linkage automatic control system to allocate the dust removal chambers that need to be closed. When the temperature of the flue gas or ash in the shut-down dust removal chamber drops to 60°C, the chamber is activated to prevent the ash from caking or reducing its fluidity due to excessively low temperature, which could lead to ash blockage.

[0017] The features and advantages of this utility model will be described in detail through embodiments and accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the connection of the flue gas inlet of this utility model; Figure 3 This is a schematic diagram of the installation of the electric air regulating damper of this utility model; Figure 4 This is a schematic diagram of the damper installation of this utility model; Figure 5 This is a schematic diagram of the damper structure of this utility model; Figure 6 This is a schematic diagram of the linkage shaft structure of this utility model; Figure 7 This is a schematic diagram of the structure of Embodiment 1 of this utility model; Figure 8 This is a schematic diagram of the structure of Embodiment 2 of this utility model; Figure 9 This is a schematic diagram of the structure of Embodiment 3 of this utility model.

[0019] In the diagram: 1. Main flue; 2. Branch flue; 21. Arc-shaped section; 22. Flue gas guide plate; 3. Electric dust collector assembly; 31. Electrostatic precipitator; 311. Dust collection chamber; 32. Dust inlet; 33. Dust outlet; 34. Partition wall; 4. Branch flue; 5. Main flue; 6. Electric damper; 61. Rotating shaft; 62. Rocker arm; 63. Linkage shaft; 64. Mounting rod; 65. Adjusting sleeve; 66. Mounting groove; 67. Mounting nut; 68. Threaded column; 7. Flue gas temperature converter; 8. Damper; 81. Windward plate; 82. Backward plate; 83. Wear-resistant lining; 9. ; 10. ; 11. First main flue; 12. Second main flue. Detailed Implementation

[0020] Example 1 See Figures 1 to 7 A wide-load coal-fired unit post-furnace dust removal system includes a main flue 1, several branch flue 2, an electric dust collector group 3, several branch flue 4, and a main flue 5 arranged sequentially. The electric dust collector group 3 is composed of several electric dust collectors 31. Each electric dust collector 31 has several dust removal chambers 311. Each dust removal chamber 311 has a dust inlet 32 ​​and a dust outlet 33. The dust inlet 32 ​​is connected to the main flue 1 through the branch flue 2, and the dust outlet 33 is connected to the main flue 5 through the branch flue 4. Electric dampers 6 are installed in both the branch flue 2 and the branch flue 4. A flue gas temperature converter 7 is installed between the branch flue 2 and the dust inlet 32.

[0021] The two ends of the flue gas inlet duct 2 are provided with arc-shaped sections 21, and arc-shaped flue gas guide plates 22 are provided in the arc-shaped sections 21. The surface of the flue gas guide plates 22 is provided with a wear-resistant metal coating.

[0022] The electric air regulating damper 6 includes several dampers 8, which are rotatably mounted in the mounting frame via a rotating shaft 61. A rocker arm 62 is mounted on the rotating shaft 61, and the rocker arm 62 is connected to the linkage shaft 63.

[0023] The linkage shaft 63 is composed of alternating mounting rods 64 and adjusting sleeves 65. The rocker arm 62 is rotatably mounted to the mounting rods 64 via pins. The mounting rods 64 have mounting grooves 66 at both ends, and mounting nuts 67 are provided at the openings of the mounting grooves 66. The adjusting sleeves 65 have threaded posts 68 at both ends, and the ends of the threaded posts 68 are threadedly mounted to the mounting nuts 67.

[0024] The damper 8 has a cross-section that is large in the middle and small at both ends. The damper 8 has extension plates at both ends. The extension plates of the damper 8 abut against each other. The windward surface of the damper 8 is provided with a wear-resistant lining 83.

[0025] The damper 8 includes a centrally symmetrical windward plate 81 and a leeward plate 82, which are arranged on both sides of the rotating shaft 61. One end of the windward plate 81 protrudes from one end of the leeward plate 82, and the other end of the leeward plate 82 protrudes from the other end of the windward plate 81.

[0026] The electric dust collector group 3 includes three electric dust collectors 31. There are two main flue ducts 1, namely the first main flue 11 and the second main flue 12. Each electric dust collector 31 has two dust collection chambers 311, which are separated by a partition wall 34. The two dust collection chambers 311 of the electric dust collector 31 located in the middle are respectively connected to the middle branch flue duct 2. One of the middle branch flue ducts 2 is connected to the first main flue 11, and the other middle branch flue duct 2 is connected to the second main flue 12.

[0027] In this embodiment, during operation, the wide-load linkage automatic control system automatically adjusts the operation of the dust removal system according to the operating load. At 60%-100% load: Dust removal chamber 311 is fully operational; At 30%-60% load: shut down both dust collectors 311. There are two shutdown methods: One option is to shut down one dust collection chamber 311 of each of the two electrostatic precipitators 31; Another option is to shut down the two dust collection chambers 311 of the electrostatic precipitator 31 located in the middle; The closed dust removal chamber 311 is adjusted according to the periodic changes. When the temperature of the flue gas or ash in the shut-down dust removal chamber 311 drops to 60°C, the chamber is started. Avoid excessively low temperatures that could cause ash to clump or reduce its fluidity, leading to ash blockage.

[0028] At 15%-30% load: shut down three to four dust collection chambers 311. There are two shutdown methods: One method is to shut down one dust collection chamber 311 of each of the three electrostatic precipitators 31, for a total of three dust collection chambers 311. Another option is to shut down the two electrostatic precipitators 31 located on both sides, thus closing a total of four dust collection chambers 311; The closed dust removal chamber 311 is adjusted according to periodic changes. When the temperature of the flue gas or ash in the shut-down chamber drops to 60°C, the chamber is activated.

[0029] Avoid excessively low temperatures that could cause ash to clump or reduce its fluidity, leading to ash blockage.

[0030] The wide-load linkage automatic control system enables energy saving and automatic load linkage adjustment of the electrostatic precipitator. Through the analysis and prediction of operating and historical data, the predictive model is implemented to achieve energy saving, emission reduction, and efficiency improvement, enhance operational levels, reduce instantaneous exceedances and maintenance failure rates, and reduce maintenance workload. It achieves automatic load linkage control under wide load variation conditions, and simultaneously performs intelligent energy-saving control, including dust removal optimization and energy-saving control. Based on the dust value at the flue gas inlet and outlet, boiler load, coal type, flue gas volume, and flue gas temperature, combined with variable calculation and analysis prediction, the system automatically regulates the unit under load changes (0-100%), especially under ultra-low load changes. This includes automatic adjustment of key high and low voltage parameters, parameter optimization, and automatic adjustment of the high-voltage power supply mode until closed-loop control is achieved, ensuring timely and reliable energy-saving management under low load conditions. Based on the coal type and boiler combustion and operating conditions, the system performs graded efficiency prediction of each electric field of the electrostatic precipitator, automatically adjusts the power supply operation power and rapping sequence, and can provide changes to downstream equipment such as ash conveying sequence.

[0031] Pneumatic vibrators are installed at locations with low anode plate vibration force. When the flue gas dust is highly viscous under low load, ammonia escape is easily caused by denitrification. Under conventional mechanical vibration, dust tends to stick to the opposite side of the vibrator, thus affecting dust removal efficiency. When the weight of the anode vibrator hammer exceeds a certain value, increasing the vibration force will reduce the lifespan of the vibrator accessories.

[0032] The electrostatic precipitator is equipped with an anti-ash-accumulation coated cathode wire and a positive charge dust collection enhancement device (dust-collecting cathode wire). The combination of the anti-ash-accumulation cathode wire and the positive charge dust collection enhancement device improves the anti-ash-accumulation performance of the cathode wire under low load, while the dust-collecting cathode wire collects positively charged dust.

[0033] The corresponding structure of the positive charge dust collection enhancement device is shown in the patent document with publication number CN119702250B, and will not be described in detail here.

[0034] Example 2 See Figure 7 The electric dust collector group 3 includes two electric dust collectors 31, each electric dust collector 31 is provided with four dust collection chambers 311, and every two adjacent dust collection chambers 311 are separated by a partition wall 34.

[0035] Everything else is the same as in Example 1.

[0036] Example 3 See Figure 8 The electric dust collector group 3 includes two electric dust collectors 31, each of which has three dust collection chambers 311, and adjacent dust collection chambers 311 are separated by partition walls 34.

[0037] Everything else is the same as in Example 1.

[0038] Comparison of modification schemes in three embodiments Taking a 1000MW unit electrostatic precipitator as an example, a comparison of different schemes is conducted. Coal quality data is shown in Table 1, and inlet flue gas conditions are shown in Table 2. The design target is to achieve an outlet dust concentration of less than 15mg / m³ under low-cost operation conditions. 3 The focus is on a detailed comparison of parameters for electrostatic precipitator solutions.

[0039] Table 1. Coal quality parameters of a 1000MW unit

[0040]

[0041] Table 2 Inlet flue gas parameters of a 1000MW unit

[0042]

[0043]

[0044] A comparison of different types of electrostatic precipitators for a 1000MW unit was conducted, and the results are as follows:

[0045]

[0046] The 3-unit 2-chamber electrostatic precipitator solution is easy to maintain, has more shutdown options, good reliability, and high fault tolerance. Therefore, the 3-unit 2-chamber electrostatic precipitator solution is selected. It is estimated that the investment will increase by 3 million yuan per unit. Under variable load operation conditions, it can reduce high voltage power consumption and save energy by about 30% (depending on the low load operation time).

[0047] During operation, the wide-load linkage automatic control system automatically adjusts the operation of the dust removal system according to the operating load: At 60%-100% load: the dust removal chamber is fully operational; At 30%-60% load: Close both dust collection chambers. There are two closing methods: One option is to close one dust chamber of each of the two electrostatic precipitators; the other option is to close both dust chambers of the electrostatic precipitator located in the middle. When shutting down two electrostatic precipitators, prioritize shutting down one dust collection chamber from each of the two precipitators located on opposite sides.

[0048] The closed dust collection chambers are adjusted according to periodic changes. When the temperature of the flue gas or ash in the shut-down dust collection chamber drops to 60°C, the chamber is activated. At 15%-30% load: Close three to four dust collection chambers. There are two closing methods: One approach is to shut down one dust collection chamber for each of the three electrostatic precipitators, for a total of three dust collection chambers. Another option is to shut down the two electrostatic precipitators located on both sides, closing a total of four dust collection chambers; The closed dust collection chambers are adjusted according to periodic changes. When the temperature of the flue gas or ash in the shut-down chamber drops to 60°C, the chamber is activated. When a power supply zone fault occurs, the room containing that power supply zone should be shut down first.

[0049] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the protection scope of the present invention.

Claims

1. A dust removal system after the furnace of a wide-load coal-fired unit, characterized in that: It includes a main flue (1), several branch flues (2), an electric dust collector group (3), several branch flues (4), and a main flue (5) arranged in sequence. The electric dust collector group (3) is composed of several electric dust collectors (31). Each electric dust collector (31) is provided with several dust collection chambers (311). Each dust collection chamber (311) is provided with a dust inlet (32) and a dust outlet (33). The dust inlet (32) is connected to the main flue (1) through the branch flue (2), and the dust outlet (33) is connected to the main flue (5) through the branch flue (4). Both the branch flue (2) and the branch flue (4) are provided with electric dampers (6). A flue gas temperature converter (7) is installed between the branch flue (2) and the dust inlet (32).

2. The wide-load coal-fired unit post-furnace dust removal system as described in claim 1, characterized in that: The two ends of the flue gas inlet (2) are provided with an arc-shaped section (21), and an arc-shaped flue gas guide plate (22) is provided in the arc-shaped section (21). The surface of the flue gas guide plate (22) is provided with a wear-resistant metal coating.

3. The wide-load coal-fired unit post-furnace dust removal system as described in claim 1, characterized in that: The electric damper (6) includes several dampers (8), which are rotatably mounted on the mounting frame via a rotating shaft (61). A rocker arm (62) is mounted on the rotating shaft (61), and the rocker arm (62) is connected to the linkage shaft (63).

4. The wide-load coal-fired unit after-furnace dust removal system as described in claim 3, characterized in that: The linkage shaft (63) consists of alternating mounting rods (64) and adjusting sleeves (65). The rocker arm (62) is rotatably mounted to the mounting rods (64) via pins. The mounting rods (64) have mounting grooves (66) at both ends. The mounting grooves (66) have mounting nuts (67) at their openings. The adjusting sleeves (65) have threaded posts (68) at both ends. The ends of the threaded posts (68) are threaded to the mounting nuts (67).

5. The wide-load coal-fired unit after-furnace dust removal system as described in claim 3, characterized in that: The cross-section of the damper (8) is a spindle-shaped structure with a large middle and small ends. The two ends of the damper (8) are provided with extension plates. The extension plates of the damper (8) abut against each other with the extension plates of the adjacent damper (8). The windward surface of the damper (8) is provided with a wear-resistant lining (83).

6. The wide-load coal-fired unit after-furnace dust removal system as described in claim 5, characterized in that: The damper (8) includes a windward plate (81) and a leeward plate (82) that are centrally symmetrical. The windward plate (81) and the leeward plate (82) are arranged on both sides of the rotating shaft (61). One end of the windward plate (81) protrudes from one end of the leeward plate (82), and the other end of the leeward plate (82) protrudes from the other end of the windward plate (81).

7. The wide-load coal-fired unit after-furnace dust removal system as described in claim 1, characterized in that: The electric dust collector group (3) includes two electric dust collectors (31), each electric dust collector (31) is provided with four dust collection chambers (311), and each two adjacent dust collection chambers (311) are separated by a partition wall (34).

8. The wide-load coal-fired unit after-furnace dust removal system as described in claim 1, characterized in that: The electric dust collector group (3) includes two electric dust collectors (31), each electric dust collector (31) is provided with three dust collection chambers (311), and adjacent dust collection chambers (311) are separated by partition walls (34).

9. The wide-load coal-fired unit post-furnace dust removal system as described in claim 1, characterized in that: The electric dust collector group (3) includes three electric dust collectors (31). There are two main flue gas ducts (1), namely the first main flue gas duct (11) and the second main flue gas duct (12). Each electric dust collector (31) has two dust collection chambers (311). The two dust collection chambers (311) are separated by a partition wall (34). The two dust collection chambers (311) of the electric dust collector (31) in the middle are respectively connected to the middle branch flue gas ducts (2). One of the middle branch flue gas ducts (2) is connected to the first main flue gas duct (11), and the other middle branch flue gas duct (2) is connected to the second main flue gas duct (12).

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