Flue gas recirculation and oxygen-enriched combustion collaborative denitration equipment for pulverized coal fired boiler

Abstract

The invention discloses flue gas recirculation and oxygen-enriched combustion collaborative denitration equipment for a pulverized coal fired boiler, and belongs to the technical field of collaborative denitration. The pulverized coal boiler comprises a heat exchange tank, and a combustion tank and a smoke return pipe are arranged in the heat exchange tank. One side of the smoke return machine shell communicates with a combustor shell, and the combustor shell communicates with the combustion tank. An igniter and a graded oxygen-enriched combustor are arranged in the combustor shell, and the graded oxygen-enriched combustor comprises a central oxygen channel structure, a pulverized coal air channel structure and a compensation oxygen channel structure; core flames of pulverized coal air are ignited through the central oxygen channel structure, then the pulverized coal air with low oxygen content sprayed out of the pulverized coal air channel structure is ignited through the core flames, and a low-oxygen combustion section close to the root of the fire tongue is formed. Oxygen is sprayed out through the compensation oxygen channel structure, so that pulverized coal air is subjected to oxidation reaction and is fully combusted; according to the invention, a staged combustion effect can be formed, nitrate substances generated by a pulverized coal oxidation reaction are greatly reduced, and the capability of denitration of combustion flue gas is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of coordinated denitrification, and specifically relates to a flue gas recirculation and oxygen-enriched combustion coordinated denitrification device for a pulverized coal boiler. Background Art

[0002] A pulverized coal boiler (Pulverized Coal Boiler) is a large-scale industrial boiler that uses pulverized coal (finely crushed coal particles) as its main fuel. It is widely used in thermal power plants, large-scale heating systems and other fields. Its core principle is to grind coal into extremely fine powder and spray it into the furnace for combustion, achieving efficient energy conversion. The device used for combustion is called a burner. Common burners directly introduce air for oxidative combustion. Since other gases in the air will also undergo oxidation reactions with the pulverized coal to form various nitrates, the subsequent flue gas purification is greatly increased.

[0003] Existing oxygen-enriched burners use high-purity oxygen instead of air, which greatly reduces the production of nitrates and reduces the cost of subsequent flue gas purification work. However, existing oxygen-enriched burners usually cause the local flame temperature to be too high due to the excessive oxygen content, resulting in serious safety accidents. Therefore, they usually work in conjunction with the flue gas recirculation system to dilute the oxygen through the flue gas, reduce the flame temperature and even out the temperature of each part. However, the existing flue gas recirculation system usually only has a high-wear-resistant blower that can adapt to high-gray turbid flue gas, and adjust the flue gas supply by adjusting the speed. This adjustment method has low adjustment accuracy, and the low speed will affect the combustion posture, causing flame disturbances and affecting the heating quality.

[0004] Although the existing oxygen-enriched burner reduces the amount of nitrates produced by air by replacing air, the impurities in the coal powder itself will also react to produce nitrates. Therefore, the combustion of inferior coal will still produce a large amount of nitrates. The existing oxygen-enriched burner is usually equipped with a cyclone at the internal air outlet to make the flue gas produce a cyclone so as to fully mix the substances ejected from each flow channel. However, there are differences in the air flow distribution for the combustion of different types of coal. Some types of coal cannot adapt to the flow posture of the existing cyclone, resulting in incomplete combustion, flue gas ash content, and increased subsequent purification costs.

[0005] Due to high-speed particle erosion at the outlet of the existing burner coal powder air duct, the wind state is often chaotic and affects the airflow dynamics; the burnout zone and reduction zone of the existing graded combustion equipment are basically fixed. For different types of coal, the impurity content is different. The relatively fixed graded areas are prone to cause insufficient coal powder reduction or insufficient combustion; therefore, the present invention improves the existing equipment to address the above problems. Summary of the Invention

[0006] The present invention overcomes the shortcomings of the prior art and proposes a pulverized coal boiler flue gas recirculation and oxygen-enriched combustion coordinated denitrification device; the present invention is achieved through the following technical solutions: The exhaust gas fan of described outer combustion gas heating unit is connected with the exhaust gas fan of described outer combustion gas heating unit, and the exhaust gas fan of described outer combustion gas heating unit is connected with the exhaust gas fan of described outer combustion gas heating unit.

[0007] Furthermore, the central oxygen duct structure includes an oxygen nozzle, a central oxygen tube and an oxygen branch tube; the front end of the oxygen nozzle is connected to the oxygen supply system, the rear end of the oxygen nozzle is connected to the front end of the central oxygen tube, and the rear end of the central oxygen tube is connected to the front ends of multiple oxygen branch tubes; the rear end of the oxygen branch tube is provided with an external thread, and the rear end of the oxygen branch tube is connected to a screw-on tube through the external thread; an ignition valve is installed and connected between the central oxygen tube and the oxygen branch tube.

[0008] Furthermore, the pulverized coal air duct structure includes a pulverized coal air connecting pipe, a central pulverized coal air duct and a pulverized coal air branch pipe; the pulverized coal air connecting pipe is connected to the pulverized coal air duct at the bottom, the front end of the pulverized coal air connecting pipe is connected to the central pulverized coal air duct, and the outer side of the central pulverized coal air duct is connected to multiple pulverized coal air branch pipes.

[0009] Furthermore, the compensation oxygen duct structure includes a compensation air duct, a compensation air ring duct and a compensation air branch duct; the front end of the compensation air duct is connected to the oxygen air nozzle, and the rear end of the compensation air duct is connected to the compensation air ring duct. The compensation air ring duct is installed and fixed on the outer wall of the central pulverized coal air duct. The rear end face of the compensation air ring duct is connected to multiple compensation air branch ducts. The compensation air branch duct is provided with a compensation air duct valve, and the rear end of the compensation air branch duct is provided with an air outlet shell; the compensation air ring duct is located on the outside of the pulverized coal air connecting pipe.

[0010] Furthermore, the staged oxygen-enriched burner also includes an adjustable swirler structure; the adjustable swirler structure includes a swirler shell, an adjustment center shaft, fixed blades, adjustable blades and a rotating column; a compensation air duct rack is fixedly mounted on the outer side of the swirler shell, and the compensation air duct rack is fixedly connected to the inner sides of multiple compensation air branches; an adjustment center shaft is coaxially connected to the swirler shell, the front end of the adjustment center shaft is connected to a motor, and the rear end of the adjustment center shaft is connected to a conical head; the motor is mounted and fixed on the front end surface of the swirler shell, and the inner side of the rear end surface of the swirler shell is connected to multiple fixed The outer end faces of the fixed fan blades are evenly fixedly connected; the inner end faces of multiple fixed fan blades are all fixedly connected to the same adjustment ring, and the adjustment ring is located on the outside of the conical head; an adjustable fan blade is provided between two adjacent fixed fan blades, and a rotating column is fixedly connected to the middle of the outer end face of the adjustable fan blade, and the rotating column is rotatably connected to the rear end of the cyclone shell, and the inner end face of the adjustable fan blade passes through the adjustment ring and is fixedly connected to an oblong sliding ring; the adjustable fan blade is rotatably connected to the adjustment ring; a sliding rod is evenly fixedly connected to the side wall of the conical head, and the sliding rod is slidably sleeved on the inner wall of the sliding ring.

[0011] Furthermore, through holes are provided on the fixed fan blades, and the spiral tubes correspond to the fixed fan blades one by one, and the spiral tubes pass through the corresponding through holes to the outside of the fixed fan blades; multiple spiral tubes are arranged in a circular array; multiple coal powder air branch pipes and air outlet head shells are all located outside the spiral tubes, and multiple coal powder air branch pipes and multiple air outlet head shells are on the same circumferential surface, and multiple spiral tubes, multiple coal powder air branch pipes, and multiple air outlet head shells are all arranged in a circular array around the same axis.

[0012] Furthermore, a high-temperature resistant lining is fixedly installed on the outer side of the compensation air duct rack; the high-temperature resistant lining is located on the outer sides of the oxygen air branch pipe, the pulverized coal air branch pipe, and the compensation air branch pipe.

[0013] Furthermore, an air inlet is fixedly installed at the front end of the air outlet housing, one end of the air inlet is connected to a compensating air branch pipe, the other end of the air inlet is connected to one end of a connecting hose, the other end of the connecting hose is connected to the air outlet, and the air outlet is rotatably connected to the rear end of the air outlet housing, one side of the air outlet is fixedly connected to a driven gear, one side of the driven gear is meshed with a relay gear, the relay gear is rotatably connected to the inside of the air outlet housing, one side of the relay gear is meshed with a driving gear, the driving gear is connected to a small motor and is rotatably connected to the inside of the air outlet housing, and the small motor is fixed to one side of the air outlet housing.

[0014] Furthermore, the flue gas fan structure includes an air supply casing, a dust filter plate is fixedly installed on the front end surface of the air supply casing, and an adjustable louver structure and an air supply assembly are provided in the air supply casing; the adjustable louver structure includes a louver frame, the louver frame is fixedly connected to the front end of the air supply casing, and louver plates are equidistantly provided on the louver frame, and the louver plates are rotatably connected to the louver frame through the louver shaft, and the louver plates are rotatably connected to each other through the synchronization rod on one side, and the louver frame is provided with an arc-shaped strip opening to cooperate with the movement path of the synchronization rod, and a belt is provided on the lowermost louver shaft of the louver plate, and the end of the belt away from the louver shaft is provided on the reduction motor, and the reduction motor is fixed to the louver frame; the air supply assembly includes a power motor, the power motor is fixed in the middle of the air supply casing, the rear end of the power motor is connected to the air supply shaft, and the rear end surface of the air supply shaft is fixedly connected to the air supply blades.

[0015] Furthermore, a burner controller is provided on the front end surface of the burner shell, and a proportioning control valve is provided on the pulverized coal air duct.

[0016] The beneficial effects of the present invention compared to the prior art are: The present invention cooperates with the central oxygen duct structure, the pulverized coal air duct structure and the compensating oxygen duct structure to preferentially reduce the oxidation reaction substances in the pulverized coal through low-purity oxygen air and pulverized coal air, and then ensures the full combustion of the pulverized coal through compensating high-purity oxygen air, forming a staged combustion effect, greatly reducing the nitrate substances produced by the pulverized coal oxidation reaction, and improving the denitrification ability of the combustion flue gas.

[0017] The present invention facilitates the free adjustment of the flue gas swirl posture through the coordination of the flue gas fan structure and the adjustable swirl structure, thereby optimizing the airflow distribution in coordination with the data model, improving the combustion efficiency of the coal powder, and realizing the ability of the denitrification equipment to fully burn different types of coal; through the coordination of the air supply component and the adjustable louver structure, it is convenient to recover the flue gas and freely adjust the flue gas supply amount, and form a dynamic ratio of flue gas and oxygen with the compensating air duct valve, thereby improving the combustion stability of the device and realizing the ability to stabilize the flame temperature.

[0018] The present invention facilitates the selection of replacement of the spiral tube according to actual needs or degree of loss through the cooperation of the pulverized coal air branch pipe and the spiral tube, thereby improving practicality; through the cooperation of the small motor and the air outlet, it is convenient to independently adjust the cutting-in angle of the compensating oxygen wind, thereby realizing dynamic adjustment of the ratio of the burnout zone and the reduction zone of the combustion, improving the adaptability of the denitrification equipment to different types of coal, and realizing the ability of the denitrification equipment to make dynamic adjustments in real time to different types of coal or different states of coal during the combustion process; ultimately solving the problems of high nitrate content in the flue gas generated by the existing equipment, poor adaptability of the existing equipment to different types of coal, and easy overheating of the flame temperature of the existing equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the overall appearance of the denitration equipment of the present invention; Figure 2 Figure 1 is a schematic diagram of the external structure of the burner shell; Figure 3 Figure 2 is a schematic diagram of the internal structure of the pulverized coal boiler; Figure 4 Figure 3 is a schematic diagram of the external structure of the staged oxygen-enriched burner; Figure 5 Figure 4 is a schematic diagram of the structure of the central oxygen channel; Figure 6 Figure 5 is a schematic diagram of the structure of the pulverized coal air duct; Figure 7 Figure 6 is a schematic diagram of the structure of the compensation oxygen channel; Figure 8 Figure 7 is a schematic diagram of the structure of the adjustable cyclone; Figure 9 Figure 8 is a schematic diagram of the structure of the adjustable air blade; Figure 10 Figure 9 is a schematic diagram of the structure of the flue gas fan; Figure 11 Figure 10 is a schematic diagram of the external structure of the adjustable louvers; Figure 12 Figure 11 is a schematic diagram of the structure of the louvers; Figure 13 Figure 12 is a schematic diagram of the structure of the air supply assembly; Figure 14 Figure 13 is a schematic diagram of the position of the air outlet head shell and the screw pipe of the bottom of the staged oxygen-enriched burner; Figure 15 Figure 14 is a schematic diagram of the external structure of the air outlet head shell; Figure 16 Figure 15 is a schematic diagram of the internal structure of the air outlet head shell.

[0020] Figure 16 is a list of the numbers in the drawings. 1. Support base; 2. Heat exchange tank; 3. Combustion tank; 4. Smoke return pipe; 5. Smoke box; 6. Smoke return machine housing; 7. Burner housing; 8. Burner controller; 9. Pulverized coal air duct; 10. Proportioning control valve; 11. High temperature resistant lining; 12. Oxygen air nozzle; 13. Central oxygen pipe; 14. Oxygen air branch pipe; 15. Pulverized coal air connecting pipe; 16. Central pulverized coal air duct; 17. Pulverized coal air branch pipe; 18. Compensating air duct; 19. Compensating air ring pipe; 20. Compensating air branch pipe; 21. Compensating air duct valve; 22. Compensating air duct rack; 23. Air outlet housing; 24. Cyclone housing; 25. Adjustment Central axis; 26. Electric motor; 27. Fixed fan blades; 28. Adjustable fan blades; 29. ​​Rotating column; 30. Sliding ring; 31. Sliding rod; 32. Air supply housing; 33. Ash filter plate; 34. Louver frame; 35. Reducer motor; 36. Belt; 37. Louver shaft; 38. Louver plate; 39. Synchronizing rod; 40. Power motor; 41. Air supply shaft; 42. Air supply blades; 43. Rotary pipe; 44. Air inlet; 45. Connecting hose; 46. Air outlet; 47. Driven gear; 48. Relay gear; 49. Driving gear; 50. Small motor; 51. Ignition valve. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. The technical solutions of the present invention will be described in detail below with reference to the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0022] See also Figures 1 to 16 This embodiment provides a flue gas recirculation and oxygen-enriched combustion coordinated denitrification device for a pulverized coal boiler, including a support base 1, which is composed of a base plate and a support plate fixed to the top surface of the base plate. A pulverized coal boiler is fixedly installed on the support base 1, and the pulverized coal boiler includes a heat exchange tank 2, and a smoke box 5 and a smoke return machine casing 6 are installed on the outer side of the front end of the heat exchange tank 2; a water inlet and a steam outlet are provided on the top surface of the heat exchange tank 2, the water inlet is used to connect to a water supply system, and the steam outlet is used to connect to a steam power generation system; a combustion tank 3 and a smoke return pipe 4 are provided inside the heat exchange tank 2. The return smoke pipe 4 is located above the combustion tank 3, and the rear end of the return smoke pipe 4 is connected to the combustion tank 3. The front end of the return smoke pipe 4 passes through the front end face of the heat exchange tank 2 and is connected to the smoke box 5. The smoke box 5 is connected to the return smoke machine casing 6 through the smoke pipe. A flue gas fan structure is provided inside the return smoke machine casing 6. One side of the return smoke machine casing 6 is connected to a burner shell 7, and the burner shell 7 is connected to the combustion tank 3; an igniter and a staged oxygen-enriched burner are provided in the burner shell 7, and a burner controller 8 is provided on the front end face of the burner shell 7. The lower end of the burner shell 7 is connected to a pulverized coal air duct 9, and a proportioning control valve 10 is provided on the pulverized coal air duct 9.

[0023] In the present invention, to address the problem of low-quality coal generating a large amount of nitrates during combustion, a staged oxygen-enriched burner is employed. The staged oxygen-enriched burner comprises a central oxygen duct structure, a pulverized coal duct structure, a compensating oxygen duct structure, and an adjustable swirler structure. The central oxygen duct structure includes an oxygen nozzle 12, a central oxygen pipe 13, and oxygen branch pipes 14. The front end of the oxygen nozzle 12 is connected to the oxygen supply system, the rear end of the oxygen nozzle 12 is connected to the front end of the central oxygen pipe 13, and the rear end of the central oxygen pipe 13 is connected to the front ends of multiple oxygen branch pipes 14. The rear end of the oxygen branch pipe 14 is externally threaded, and the rear end of the oxygen branch pipe 14 is connected to a screw-on pipe 43 via the external threads. An ignition valve 51 is installed and connected between the central oxygen pipe 13 and the oxygen branch pipe 14.

[0024] The pulverized coal air duct structure includes a pulverized coal air connecting pipe 15, a central pulverized coal air duct 16 and a pulverized coal air branch pipe 17; the pulverized coal air connecting pipe 15 is connected to the pulverized coal air duct 9 at the bottom, the front end of the pulverized coal air connecting pipe 15 is connected to the central pulverized coal air duct 16, and the outer side of the central pulverized coal air duct 16 is connected to multiple pulverized coal air branch pipes 17; the pulverized coal air duct 9 is used to connect to the coal supply system.

[0025] The compensating oxygen duct structure includes a compensating air duct 18, a compensating air ring duct 19, and a compensating air branch duct 20. The front end of the compensating air duct 18 is connected to the oxygen air nozzle 12, and the rear end is connected to the compensating air ring duct 19. The compensating air ring duct 19 is fixed to the outer wall of the central pulverized coal air duct 16. The rear end of the compensating air ring duct 19 is connected to multiple compensating air branch ducts 20. The compensating air branch ducts 20 are equipped with a compensating air duct valve 21, and the rear end of the compensating air branch duct 20 is equipped with an air outlet housing 23. The compensating air ring duct 19 is located outside the pulverized coal air connecting pipe 15.

[0026] The adjustable cyclone structure includes a cyclone shell 24, an adjustment shaft 25, fixed blades 27, adjustable blades 28 and a rotating column 29; the outer side of the cyclone shell 24 is fixedly mounted with a compensation air duct rack 22, which is fixedly connected to the inner side of multiple compensation air branches 20; the cyclone shell 24 is coaxially connected to the adjustment shaft 25, the front end of the adjustment shaft 25 is connected to the motor 26, and the rear end of the adjustment shaft 25 is connected to the conical head; the motor 26 is mounted and fixed on the front end surface of the cyclone shell 24, and the inner side of the rear end surface of the cyclone shell 24 is evenly connected to the outer end surface of multiple fixed blades 27 Fixed connection; the inner end faces of multiple fixed fan blades 27 are fixedly connected to the same adjustment ring, and the adjustment ring is located outside the conical head; an adjustable fan blade 28 is provided between two adjacent fixed fan blades 27, and a rotating column 29 is fixedly connected to the middle of the outer end face of the adjustable fan blade 28, and the rotating column 29 is rotatably connected to the rear end of the cyclone shell 24. The inner end face of the adjustable fan blade 28 passes through the adjustment ring and is fixedly connected to an oblong sliding ring 30; the adjustable fan blade 28 is rotatably connected to the adjustment ring; sliding rods 31 are evenly fixedly connected to the side wall of the conical head, and the sliding rods 31 are slidably sleeved on the inner wall of the sliding ring 30. When the motor 26 drives the adjusting central shaft 25 to rotate, thereby driving the conical head to rotate, and the conical head drives the sliding rod 31 to rotate around the center. At the same time, since the sliding ring 30 is sleeved on the sliding rod 31, and one end of the sliding ring 30 is fixedly connected to the lower end of the adjustable fan blade 28, the sliding rod 31 drives the sliding ring 30 to rotate and the sliding rod 31 itself slides in the sliding ring 30. The rotation of the sliding ring 30 drives the adjustable fan blade 28 to rotate, thereby changing the relative angle between the adjustable fan blade 28 and the fixed fan blade 27, which can adjust the angle of smoke ejection and optimize the airflow distribution.

[0027] The fixed fan blades 27 are provided with through holes, and the screw-on tubes 43 correspond to the fixed fan blades 27 one by one, and the screw-on tubes 43 pass through the corresponding through holes to the outside of the fixed fan blades 27; multiple screw-on tubes 43 are arranged in a circular array.

[0028] Multiple pulverized coal air branch pipes 17 and multiple air outlet housings 23 are all located outside the spiral tube 43, and multiple pulverized coal air branch pipes 17 and multiple air outlet housings 23 are on the same circumferential surface. Multiple spiral tubes 43, multiple pulverized coal air branch pipes 17, and multiple air outlet housings 23 are all arranged in a circular array around the same axis.

[0029] A high temperature resistant lining 11 is fixedly installed on the outer side of the compensation air duct frame 22 ; the high temperature resistant lining 11 is located outside the oxygen air branch pipe 14 , the pulverized coal air branch pipe 17 , and the compensation air branch pipe 20 .

[0030] The coordination of the central oxygen duct, pulverized coal air duct, and compensating oxygen duct allows for preferential reduction of oxidizing substances in the pulverized coal through low-purity oxygen and pulverized coal air. High-purity oxygen air is then used to ensure full combustion of the pulverized coal, creating a staged combustion effect that significantly reduces the production of nitrates by the pulverized coal oxidation reaction. The adjustable cyclone structure allows for free adjustment of the flue gas cyclonic flow, optimizing airflow distribution in conjunction with data models and improving pulverized coal combustion efficiency.

[0031] The flue gas fan structure includes an air supply casing 32 , a dust filter plate 33 is fixedly mounted on the front end surface of the air supply casing 32 , and an adjustable louver structure and an air supply component are arranged inside the air supply casing 32 .

[0032] In the present invention, in order to solve the problem that there are differences in airflow distribution when burning different types of coal, some types of coal cannot adapt to the flow posture of the existing cyclone and cause incomplete combustion, a technical solution of an adjustable louver structure is adopted; the adjustable louver structure includes a louver frame 34, the louver frame 34 is fixedly connected to the front end of the inner part of the air supply housing 32, and louver plates 38 are equidistantly arranged on the louver frame 34, and the louver plates 38 are rotatably connected to the louver frame 34 through the louver shaft 37. The louver plates 38 are rotatably connected to each other through the synchronization rod 39 on one side, and the louver frame 34 is provided with an arc-shaped strip opening to cooperate with the movement path of the synchronization rod 39. The most A belt 36 is sleeved on a louver shaft 37 below, and the end of the belt 36 away from the louver shaft 37 is sleeved on the reduction motor 35, and the reduction motor 35 is installed and fixed on the louver frame 34; the air supply component includes a power motor 40, and the power motor 40 is installed and fixed in the middle of the air supply casing 32. The rear end of the power motor 40 is connected to the air supply shaft 41, and the rear end face of the air supply shaft 41 is fixedly connected to the air supply blade 42. Through the cooperation of the air supply component and the adjustable louver structure, it is convenient to recover the flue gas and adjust the flue gas supply amount, and form a dynamic ratio of flue gas and oxygen with the compensating air duct valve 21, thereby improving the combustion stability of the device.

[0033] In the present invention, in order to solve the problem of insufficient reduction or insufficient combustion of coal powder caused by a relatively fixed grading area, the following technical solution is adopted: an air inlet 44 is fixedly installed at the front end of the air outlet housing 23, one end of the air inlet 44 is connected to the compensation air branch pipe 20, the other end of the air inlet 44 is connected to one end of the connecting hose 45, and the other end of the connecting hose 45 is connected to the air outlet 46, the air outlet 46 is rotatably connected to the rear end of the air outlet housing 23, and a driven gear 47 is fixedly connected to one side of the air outlet 46. The side is meshed with a relay gear 48, which is rotatably connected to the inside of the air outlet housing 23. One side of the relay gear 48 is meshed with a driving gear 49, which is connected to a small motor 50 and rotatably connected to the inside of the air outlet housing 23. The small motor 50 is installed and fixed on one side of the air outlet housing 23. Through the cooperation of the small motor 50 and the air outlet 46, it is convenient to autonomously adjust the cutting-in angle of the compensating oxygen wind, thereby realizing dynamic adjustment of the ratio of the burnout zone and the reduction zone of the combustion, and improving the adaptability of the device to the type of coal.

[0034] In this embodiment, a method for using a flue gas recirculation and oxygen-enriched combustion synergistic denitrification device for a pulverized coal boiler is also proposed, comprising the following steps: Step 1: First, power all electrical equipment. Then, connect the water pipe and steam power generation system through the water inlet and steam outlet above the heat exchange tank 2, respectively. Then, install and fix the burner housing 7 on the front face of the heat exchange tank 2 and connect it to the combustion tank 3. Then, install and fix the smoke return housing 6 on one side of the burner housing 7, and connect the burner housing 7 and the smoke return housing 6, and then connect the smoke return housing 6 and the smoke box 5. Connect one end of the pulverized coal air duct 9 to the coal supply system and the other end to the pulverized coal air connecting pipe 15. Then, connect the oxygen air nozzle 12 to the oxygen supply system. Finally, select the screw-on pipe 43 made of appropriate material as needed to complete all installation work. After debugging the burner controller 8, you can start heating.

[0035] Step 2. After starting the heating work, pure water is first introduced into the heat exchange tank 2 through the water supply system. After it is filled with water, high-purity oxygen and low-oxygen pulverized coal air are supplied to the central oxygen pipe 13 and the central pulverized coal air pipe 16 through the oxygen supply system and the coal supply system. First, high-purity oxygen enters the oxygen air branch pipe 14 through the central oxygen pipe 13. At this time, the ignition valve 51 remains unobstructed, and the oxygen is then ejected from the spiral pipe 43 through the oxygen air branch pipe 14. The oxygen ejected from the spiral pipe 43 is then ignited by the igniter to form a high-temperature core flame for igniting the pulverized coal air. The high-temperature core flame is then used to ignite the low-oxygen pulverized coal air ejected from the pulverized coal air branch pipe 17, thereby forming a low-oxygen combustion section near the root of the flame. The supply of the central oxygen pipe 13 is then cut off by the ignition valve 51. Oxygen. At this time, due to the low oxygen content in the pulverized coal air, the impurities inside the pulverized coal do not have enough oxygen to undergo oxidation reactions during combustion to produce pollutants such as nitric oxides, so they turn to reduction reactions to generate other substances. However, due to the poor heat release capacity of the reduction reaction, the ultimate goal of the device is still heating, so it is necessary to increase the oxygen content of the flame in the second half of the flame. At this time, the compensating air duct valve 21 controls the compensating air branch pipe 20 to spray high-purity oxygen, so that the second half of the flame can have enough oxygen to undergo oxidation reactions, obtain a higher flame temperature and fully burn the pulverized coal, thus forming a low-oxygen reduction zone near the root of the flame and an oxygen-rich combustion zone in the second half of the flame, thereby ensuring both the full combustion of the pulverized coal and the generation of nitric oxide pollutants during the combustion of the pulverized coal.

[0036] In step three, a large amount of low-oxygen flue gas is generated during combustion inside the device. At this time, the power motor 40 is started to rotate the air supply blades 42 via the air supply shaft 41, creating a negative pressure environment. This allows part of the flue gas in the smoke return pipe 4 and smoke box 5 to pass into the air supply housing 32. After filtering out some ash through the ash filter plate 33, the flue gas passes through the air supply blades 42 and enters the smoke return housing 6, and then enters the burner housing 7. During the ventilation period, the belt 36 can be controlled by the reduction motor 35 to rotate, thereby controlling the rotation of the louver 38 at the bottom of the louver frame 34. At the same time, the synchronization rod 39 controls the synchronous rotation of the remaining louvers 38, thereby adjusting the amount of incoming smoke. The flue gas can suppress the oxidation reaction of the flame to a certain extent. This, in conjunction with the compensation air duct valve 21, achieves a dynamic ratio of flue gas and oxygen, dynamically controls the flame temperature, and avoids local overheating of the flame.

[0037] In step four, after the flue gas enters the burner shell 7, it enters the cyclone shell 24, and then the flue gas is ejected from the fitting gap between the fixed fan blades 27 and the adjustable fan blades 28, driving the flue gas to a certain angle, thereby driving the oxygen wind and coal powder wind to rotate and mix, thereby improving the combustion efficiency. During this period, depending on the type of coal, the motor 26 can be used to drive the adjustment shaft 25 to rotate, thereby driving the conical head at the end of the adjustment shaft 25 to rotate, and the conical head drives the sliding rod 31 to rotate around the center. At the same time, since the sliding ring 30 is mounted on the sliding rod 31, and one end of the sliding ring 30 is fixedly connected to the lower end of the adjustable fan blade 28, the sliding rod 31 drives the sliding ring 30 to rotate, and the rotation of the sliding ring 30 drives the adjustable fan blade 28 to rotate, thereby changing the relative angle between the adjustable fan blade 28 and the fixed fan blade 27, thereby adjusting the flue gas ejection angle and optimizing the airflow distribution.

[0038] Step 5. During the operation of the staged oxygen-enriched burner, the small motor 50 can be started to drive the driving gear 49 to rotate according to the actual combustion conditions of the pulverized coal or special needs, and then the driven gear 47 can be driven to rotate through the relay gear 48, thereby driving the air outlet 46 to rotate, changing the compensation wind cut-in angle, thereby extending or shortening the reduction zone length in the staged combustion, thereby achieving the best pulverized coal combustion state. After the high-temperature flame is ejected from the staged oxygen-enriched burner, it heats the combustion tank 3, thereby boiling the pure water in the heat exchange tank 2 to generate steam, which is then supplied to the power generation system to complete power generation. At the same time, part of the flue gas behind the flame is drawn back into the burner shell 7 through the flue gas fan structure, and the other part of the flue gas enters the external purification system. This cycle completes the power generation work of the entire power station and discharges clean air.

[0039] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be considered that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the present invention, which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims

1. A synergistic denitration device for flue gas recirculation and oxygen-enriched combustion for a pulverized coal boiler, the pulverized coal boiler comprising a heat exchange tank (2), a smoke box (5) and a smoke return machine housing (6) being installed on the outside of the heat exchange tank (2); a combustion tank (3) and a smoke return pipe (4) being provided inside the heat exchange tank (2); one end of the smoke return pipe (4) being connected to the combustion tank (3), the other end of the smoke return pipe (4) being connected to the smoke box (5), the smoke box (5) being connected to the smoke return machine housing (6) through the smoke pipe; one side of the smoke return machine housing (6) being connected to a burner housing (7), the burner housing (7) being connected to the combustion tank (3); characterized in that A flue gas fan structure is provided inside the smoke return housing (6), an igniter and a staged oxygen-enriched burner are provided inside the burner housing (7), a pulverized coal air duct (9) is connected to the lower end of the burner housing (7), and the pulverized coal air duct (9) is used to connect to the coal supply system; the staged oxygen-enriched burner comprises a central oxygen channel structure, a pulverized coal air duct structure and a compensation oxygen channel structure; the central oxygen channel structure is used to ignite a core flame of the pulverized coal air, and then the core flame ignites the low-oxygen pulverized coal air ejected from the pulverized coal air duct structure, forming a low-oxygen combustion section near the root of the flame; oxygen is ejected through the compensation oxygen channel structure, so that the pulverized coal air undergoes an oxidation reaction and burns fully.

2. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 1, characterized in that: The central oxygen channel structure includes an oxygen nozzle (12), a central oxygen tube (13) and an oxygen branch tube (14); the front end of the oxygen nozzle (12) is connected to the oxygen supply system, the rear end of the oxygen nozzle (12) is connected to the front end of the central oxygen tube (13), and the rear end of the central oxygen tube (13) is connected to the front ends of multiple oxygen branch tubes (14); the rear end of the oxygen branch tube (14) is provided with an external thread, and the rear end of the oxygen branch tube (14) is connected to a screw-on tube (43) through the external thread; an ignition valve (51) is installed and connected between the central oxygen tube (13) and the oxygen branch tube (14).

3. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 2, characterized in that: The pulverized coal air duct structure comprises a pulverized coal air connecting pipe (15), a central pulverized coal air duct (16) and a pulverized coal air branch pipe (17); the pulverized coal air connecting pipe (15) is connected to the pulverized coal air duct (9) at its lower portion, the front end of the pulverized coal air connecting pipe (15) is connected to the central pulverized coal air duct (16), and the outer side of the central pulverized coal air duct (16) is connected to a plurality of pulverized coal air branch pipes (17) on all sides.

4. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 3, characterized in that: The compensation oxygen duct structure includes a compensation air duct (18), a compensation air ring duct (19) and a compensation air branch duct (20); the front end of the compensation air duct (18) is connected to the oxygen air nozzle (12), and the rear end of the compensation air duct (18) is connected to the compensation air ring duct (19); the compensation air ring duct (19) is fixed on the outer wall of the central pulverized coal air duct (16); a plurality of compensation air branch ducts (20) are connected around the rear end surface of the compensation air ring duct (19); a compensation air duct valve (21) is provided on the compensation air branch duct (20); and an air outlet housing (23) is provided at the rear end of the compensation air branch duct (20); the compensation air ring duct (19) is located outside the pulverized coal air connecting pipe (15).

5. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 4, characterized in that: The staged oxygen-enriched burner further comprises an adjustable cyclone structure; the adjustable cyclone structure comprises a cyclone shell (24), an adjusting central shaft (25), fixed blades (27), adjustable blades (28) and a rotating column (29); a compensation air duct frame (22) is fixedly mounted on the outer side of the cyclone shell (24), and the compensation air duct frame (22) is fixedly connected to the inner side of the plurality of compensation air branch pipes (20); the cyclone shell (24) is coaxially rotatably connected with the adjusting central shaft (25), the front end of the adjusting central shaft (25) is connected to the motor (26), and the rear end of the adjusting central shaft (25) is connected to the conical head; the motor (26) is mounted and fixed on the front end surface of the cyclone shell (24), and the inner side of the rear end surface of the cyclone shell (24) is connected to the The outer end surfaces of the plurality of fixed fan blades (27) are uniformly fixedly connected; the inner end surfaces of the plurality of fixed fan blades (27) are all fixedly connected to the same adjustment ring, and the adjustment ring is located outside the conical head; an adjustable fan blade (28) is provided between two adjacent fixed fan blades (27); a rotating column (29) is fixedly connected to the middle of the outer end surface of the adjustable fan blade (28); the rotating column (29) is rotatably connected to the rear end of the cyclone shell (24); the inner end surface of the adjustable fan blade (28) passes through the adjustment ring and is fixedly connected to an oblong sliding ring (30); the adjustable fan blade (28) is rotatably connected to the adjustment ring; a sliding rod (31) is uniformly fixedly connected to the side wall of the conical head, and the sliding rod (31) is slidably sleeved on the inner wall of the sliding ring (30).

6. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 5, characterized in that: The fixed fan blade (27) is provided with a through hole, and the spiral tube (43) corresponds to the fixed fan blade (27) one by one, and the spiral tube (43) passes through the corresponding through hole to the outside of the fixed fan blade (27); the plurality of spiral tubes (43) are arranged in a circular array; the plurality of pulverized coal air branch pipes (17) and the air outlet head shell (23) are all located outside the spiral tube (43), and the plurality of pulverized coal air branch pipes (17) and the plurality of air outlet head shells (23) are on the same circumferential surface, and the plurality of spiral tubes (43), the plurality of pulverized coal air branch pipes (17), and the plurality of air outlet head shells (23) are all arranged in a circular array around the same axis.

7. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 6, characterized in that: A high-temperature resistant lining (11) is fixedly mounted on the outer side of the compensation air duct frame (22); the high-temperature resistant lining (11) is located outside the oxygen air branch pipe (14), the pulverized coal air branch pipe (17), and the compensation air branch pipe (20).

8. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 4, characterized in that: An air inlet (44) is fixedly installed at the front end of the air outlet housing (23), one end of the air inlet (44) is connected to the compensation air branch pipe (20), the other end of the air inlet (44) is connected to one end of the connecting hose (45), and the other end of the connecting hose (45) is connected to the air outlet (46), and the air outlet (46) is rotatably connected to the rear end of the air outlet housing (23). A driven gear (47) is fixedly connected to one side of the air outlet (46), and a relay gear (48) is meshedly connected to one side of the driven gear (47). The relay gear (48) is rotatably connected to the inside of the air outlet housing (23), and a driving gear (49) is meshedly connected to one side of the relay gear (48). The driving gear (49) is connected to a small motor (50) and is rotatably connected to the inside of the air outlet housing (23). The small motor (50) is fixedly installed on one side of the air outlet housing (23).

9. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 1, characterized in that: The smoke fan structure includes an air supply casing (32), a dust filter plate (33) is fixedly mounted on the front end surface of the air supply casing (32), and an adjustable louver structure and an air supply component are arranged inside the air supply casing (32); the adjustable louver structure includes a louver frame (34), the louver frame (34) is fixedly connected to the front end of the air supply casing (32), louver plates (38) are equidistantly arranged on the louver frame (34), the louver plates (38) are rotatably connected to the louver frame (34) through louver shafts (37), and the louver plates (38) are rotatably connected to each other through a synchronization rod (39) on one side. The louver frame ( 34) is provided with an arc-shaped strip opening in cooperation with the motion path of the synchronization rod (39), and a belt (36) is provided on the lowermost shutter shaft (37) in the shutter plate (38), and the end of the belt (36) away from the shutter shaft (37) is provided on the reduction motor (35), and the reduction motor (35) is fixed on the shutter frame (34); the air supply component includes a power motor (40), the power motor (40) is fixed in the middle of the air supply housing (32), the rear end of the power motor (40) is connected to the air supply shaft (41), and the rear end surface of the air supply shaft (41) is fixedly connected to the air supply blade (42).

10. The flue gas recirculation and oxygen-enriched combustion synergistic denitrification equipment for pulverized coal boilers according to claim 1, characterized in that: A burner controller (8) is provided on the front end surface of the burner shell (7), and a proportioning control valve (10) is provided on the pulverized coal air duct (9).

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