Flue gas recirculation system and method for improving performance of household garbage incineration power generation boiler

Abstract

The invention provides a household garbage incineration power generation boiler performance improvement flue gas recirculation system which comprises an incinerator, and a primary air mechanism is arranged on one side of the incinerator; a waste heat boiler is arranged on one side of the incinerator, a semi-dry method deacidification tower is arranged on one side of the waste heat boiler, a bag-type dust collector is arranged on one side of the semi-dry method deacidification tower, and an induced draft fan is arranged on one side of the bag-type dust collector; smoke recirculation is matched with low-oxygen combustion, so that the boiler efficiency can be improved, and the boiler evaporation capacity is increased. By means of flue gas recirculation low-NOx combustion, the original generation amount of nitric oxide can be reduced by about 30%, the usage amount of denitration agents at the rear end is reduced, and the production cost is reduced; and meanwhile, the pressure of a rear-end denitration system is reduced, and the emission concentration of nitrogen oxide and ammonia escape can be controlled at a lower level. Flue gas generated after biogas combustion is fed into primary air to be mixed and then fed into a drying section of a lower air chamber of the incinerator to dry garbage, the functionality of biogas combustion heat energy is fully exerted, and the steam consumption of a primary air preheater can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of domestic waste incineration power generation, and in particular to a flue gas recirculation system and method for improving the performance of a domestic waste incineration power generation boiler. Background Art

[0002] Incineration of domestic waste for power generation is currently the most mainstream method of waste reduction and harmless treatment. Compared with other treatment methods such as sanitary landfill and composting, the flue gas emitted by waste incineration for power generation contains a large amount of pollutants. Flue gas purification has always been a difficulty in waste incineration for power generation. Among them, it is difficult to control the concentration of NOx nitrogen oxides and ammonia fugitive emissions, which is a prominent problem in the industry.

[0003] As the country's requirements for air quality become increasingly stringent, provinces and cities have gradually issued local standards for waste incineration flue gas emissions, and the requirements for the reduction of nitrogen oxides are becoming increasingly stringent. Some provinces and cities have NOx emission requirements of 120mg / Nm 3 , while ammonia escape is less than 8mg / Nm 3 , which poses a higher challenge to the existing flue gas treatment process. Although SCR can meet the requirements, the operating cost is too high.

[0004] Studying low NOx combustion technology and controlling the original NOx generation is one of the effective technical measures to reduce the cost of flue gas treatment.

[0005] Some domestic waste incineration power generation companies have done a lot of research and practice work on low NOx combustion and have achieved certain research results. However, in the operation of specific projects, there are more or less some problems that affect the long-term stable operation of the system, and the technical means are single. For example, CO concentration exceeds the standard, the furnace temperature is low when burning low calorific value waste or running at low load, system pipeline corrosion, poor operation stability, and failure to achieve the expected design effect. Summary of the invention

[0006] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the present invention is to provide a flue gas recirculation system for improving the performance of domestic waste incineration power generation boilers, which effectively solves some problems that affect the long-term stable operation of the system in the operation of specific projects, and the technical means are single. For example, CO concentration exceeds the standard, the furnace temperature is low when burning low calorific value garbage or running at low load, the system pipeline is corroded, the operation stability is poor, and the expected design effect cannot be achieved.

[0007] On the one hand, the technical solution provided by the present invention is to provide a flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler, comprising an incinerator, one side of which is provided with a primary air mechanism;

[0008] A waste heat boiler is arranged on one side of the incinerator, a semi-dry deacidification tower is arranged on one side of the waste heat boiler, a bag filter is arranged on one side of the semi-dry deacidification tower, and an induced draft fan is arranged on one side of the bag filter;

[0009] A circulation fan is provided on one side of the induced draft fan, a first nozzle and a second nozzle are provided on one side of the circulation fan, the first nozzle is provided obliquely downward on one side of the waste heat boiler, the second nozzle is provided obliquely upward on one side of the waste heat boiler, a secondary fan is provided on one side of the waste heat boiler, a front wall combustion-supporting secondary air gate nozzle and a rear wall combustion-supporting secondary air gate nozzle are provided at the output end of the secondary fan, the front wall combustion-supporting secondary air gate nozzle is provided obliquely downward on one side of the waste heat boiler, the rear wall combustion-supporting secondary air gate nozzle is provided obliquely upward on one side of the waste heat boiler, and a detection component is installed on one side of the waste heat boiler;

[0010] A low calorific value garbage burning mechanism is provided between the circulating fan and the incinerator;

[0011] A biogas inlet mechanism is also arranged on one side of the incinerator.

[0012] Preferably, the waste heat boiler, semi-dry deacidification tower and bag-type dust collector are interconnected through a smoke duct in sequence, and an induced draft fan connected to the flue is arranged on the side of the bag-type dust collector facing away from the semi-dry deacidification tower, and an induced draft fan is arranged on the other side of the induced draft fan connected to the flue.

[0013] Preferably, the incinerator includes a garbage feed inlet, an incinerator grate is provided on one side of the garbage feed inlet, an incinerator downwind chamber drying section is provided on one side of the incinerator grate, an incinerator downwind chamber combustion and burnout section is provided on one side of the incinerator downwind chamber drying section, and a slag discharge port is provided on one side of the incinerator downwind chamber combustion and burnout section.

[0014] Preferably, the primary air mechanism includes a primary air fan, an air preheating chamber is provided at the air outlet end of the primary air fan through a pipeline, a flue gas mixer is provided at the air outlet end of the air preheating chamber through a primary air duct A, the air outlet end of the flue gas mixer is connected to the drying section of the lower air chamber of the incinerator through a pipeline, an electric regulating damper A is provided at one end of the primary air duct A close to the flue gas mixer, and the middle part of the primary air duct A is connected to the combustion and burnout section of the lower air chamber of the incinerator through a primary air duct B.

[0015] Preferably, the induced draft fan and the circulating fan are connected to each other through a recirculation fan inlet flue, an electric damper A is provided on one side of the recirculation fan inlet flue, and a bypass purge air electric damper is also provided on one side of the recirculation fan inlet flue through a pipeline, a circulating fan outlet flue is provided at the air outlet end of the circulating fan, an electric damper B is provided on one side of the circulating fan outlet flue, a front wall header and a rear wall header are provided at the air outlet end of the circulating fan outlet flue, one end of the front wall header is connected and installed on the first nozzle, one end of the rear wall header is connected and installed on the second nozzle, a secondary fan outlet duct is provided on one side of the secondary fan, an air supply header A and an air supply header B are provided at the air outlet end of the secondary fan outlet duct, one side of the air supply header A is installed on the air inlet end of the front wall combustion-supporting secondary air gate nozzle, and the air supply header B is connected and installed on the air inlet end of the rear wall combustion-supporting secondary air gate nozzle.

[0016] Preferably, the waste heat boiler includes a front wall of the waste heat boiler, a front arch water-cooled wall is arranged at the bottom of the front wall of the waste heat boiler, the front arch water-cooled wall is arranged on one side of the garbage feed port, a rear arch water-cooled wall is arranged on one side of the slag discharge port, a rear wall water-cooled wall is arranged on the top of the rear arch water-cooled wall, a furnace top water-cooled wall is arranged on the top of the front wall of the waste heat boiler, a furnace cavity is arranged on one side of the furnace top water-cooled wall and the rear wall water-cooled wall, and an economizer is arranged inside the furnace cavity.

[0017] Preferably, the detection component includes a CO\O2 online laser gas analyzer installed on one side of the front wall of the waste heat boiler, and a zirconium oxide online oxygen analyzer is installed at the outlet of the economizer.

[0018] Preferably, the low calorific value garbage burning mechanism comprises a recirculating flue gas bypass pipe A arranged at one side of the circulating fan outlet flue, an electric damper C is arranged on one side of the recirculating flue gas bypass pipe A, a flue gas preheater is arranged at the gas outlet end of the recirculating flue gas bypass pipe A, the flue gas preheater is connected to the flue gas mixer through the recirculating flue gas bypass pipe B, and an electric regulating damper B is arranged on one side of the recirculating flue gas bypass pipe B;

[0019] The recirculation fan inlet flue, the circulation fan outlet flue, the recirculation flue gas bypass duct A and the recirculation flue gas bypass duct B are all glass fiber reinforced plastic ventilation ducts.

[0020] Preferably, the biogas inlet mechanism includes a biogas combustion chamber, a biogas auxiliary burner is provided on one side of the biogas combustion chamber, a biogas pipeline is provided on one side of the biogas auxiliary burner, a biogas combustion-supporting fan is provided on one side of the biogas pipeline, the biogas combustion chamber is interconnected with the flue gas mixer through a biogas flue pipe, and an electric damper D is provided on one side of the biogas flue pipe.

[0021] On the other hand, the technical solution provided by the present invention is to provide a method for using a flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler, including the following method: the waste enters the incinerator grate from the waste feed port for combustion, and the flue gas of the incinerator is discharged from the waste heat boiler and enters the semi-dry deacidification tower, the bag filter, the induced draft fan connected flue and the induced draft fan into the chimney in sequence under the suction force of the induced draft fan;

[0022] Primary air: The air provided by the primary fan is heated in the air preheating chamber and sent to the drying section of the lower air chamber of the incinerator and the combustion section of the lower air chamber of the incinerator after being mixed by the flue gas mixer. The heat source required for heating the air preheating chamber comes from the boiler drum and the first extraction of the steam turbine;

[0023] Recirculating flue gas: close the electric damper C, and the recirculating flue gas is sent into the front wall header and the rear wall header of the furnace through the circulating fan, and then sent into the furnace through the first nozzle and the second nozzle to fully stir the high-temperature flue gas in the furnace. When the recirculating system stops operating, close the electric damper A, and start the bypass purge air electric damper at the same time, and use the negative pressure of the circulating fan to inhale fresh air to purge the pipeline;

[0024] Combustion-supporting secondary air: The secondary fan delivers air to the air inlet header A and the air inlet header B through the secondary fan outlet duct, and then delivers the air into the furnace through the front wall combustion-supporting secondary air door nozzle and the rear wall combustion-supporting secondary air door nozzle. The CO\O2 online laser gas analyzer and the zirconium oxide online oxygen analyzer detect the average gas concentration. When the CO concentration in the furnace is high and the oxygen content is low, the secondary fan quickly adjusts the operating frequency and the primary fan appropriately increases the frequency to ensure stable combustion and the CO concentration does not exceed the standard;

[0025] Burning low calorific value garbage: close the electric damper B, open the electric damper C and the electric regulating damper B, the recirculated flue gas passes through the recirculated flue gas bypass duct A, the flue gas preheater and the flue gas mixer in turn, and is mixed with the primary air and then sent to the drying section of the lower wind chamber of the incinerator. Then the flue gas preheater heats the recirculated flue gas to 220-250℃, and the heating heat source comes from the steam from the drum or the first extraction of the steam turbine;

[0026] Biogas entering the furnace: biogas is sent to the biogas combustion chamber for combustion. The biogas auxiliary burner is equipped with a separate biogas combustion auxiliary fan. The flue gas after combustion is sent to the flue gas mixer through the biogas flue gas pipeline to mix with the primary air, and finally sent to the drying section of the lower wind chamber of the incinerator; when the recycled flue gas and the biogas combustion flue gas enter the drying section of the lower wind chamber of the incinerator at the same time, the electric regulating damper A is adjusted to control the primary air volume entering the drying section of the lower wind chamber of the incinerator.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. Flue gas recirculation combined with low-oxygen combustion can improve boiler efficiency and increase boiler evaporation.

[0029] 2. Flue gas recirculation low NOx combustion can reduce the original generation of nitrogen oxides by about 30%, save the use of back-end denitrification agents, and reduce production costs; at the same time, it reduces the pressure on the back-end denitrification system and is also conducive to controlling the nitrogen oxide emission concentration and ammonia escape at a lower level.

[0030] 3. The flue gas after biogas combustion is sent to the primary air for mixing, and then sent to the drying section of the lower wind chamber of the incinerator to dry the garbage, which fully utilizes the functionality of the biogas combustion heat energy and can reduce the steam consumption of the primary air preheater.

[0031] 4. The recycled flue gas is sent into the lower wind chamber of the incinerator to dry the garbage, which enhances the adaptability of the flue gas recirculation system to the combustion of low calorific value garbage and can reduce the steam consumption of the primary air preheater.

[0032] 5. The implementation of flue gas recirculation can enhance the reducing atmosphere of the furnace and reduce the high-temperature corrosion of the heating surface in the furnace. At the same time, the reduction in local furnace temperature caused by flue gas recirculation can also reduce coking in the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a first-view structural schematic diagram of a flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to the present invention.

[0034] Figure 2 It is a structural schematic diagram of the primary air mechanism, incinerator and waste heat boiler of the present invention.

[0035] Figure 3 It is a structural schematic diagram of the combustion-supporting secondary air system of the present invention.

[0036] Figure 4 It is a structural schematic diagram of the mechanism for burning low calorific value garbage of the present invention.

[0037] Figure 5 It is a schematic structural diagram of the nozzle of the present invention from a first viewing angle.

[0038] Figure 6 It is a schematic structural diagram of the nozzle of the present invention from a second viewing angle.

[0039] Figure 7 It is a schematic structural diagram of the nozzle of the present invention from a third viewing angle.

[0040] Figure 8 It is a structural schematic diagram of the nozzle and the waste heat boiler of the present invention.

[0041] Fig. 9 It is a structural schematic diagram of the nozzle and the incinerator of the present invention.

[0042] Explanation of the symbols in the schematic diagram:

[0043] 1. induced draft fan; 2. induced draft fan connected to flue; 3. electric damper A; 4. bypass purge air electric damper; 5. recirculation fan inlet flue; 6. circulation fan; 7. secondary fan; 8. primary fan; 9. circulation fan outlet flue;

[0044] 10. Secondary fan outlet air duct; 11. Air supply header A; 12. Air supply header B; 13. Front wall header; 14. Rear wall header; 15. Electric damper B; 16. Electric damper C; 17. Recirculating flue gas bypass duct A; 18. Flue gas preheater; 19. Recirculating flue gas bypass duct B;

[0045] 20. Electric damper B; 21. Flue gas mixer; 22. Primary air duct A; 23. Air preheating chamber; 24. Primary air duct B; 25. Combustion and burnout section of lower air chamber of incinerator; 26. Front wall of waste heat boiler; 27. Rear wall water-cooled wall; 28. Furnace top water-cooled wall; 29. ​​Front arch water-cooled wall;

[0046] 30. Rear arch water-cooled wall; 31. Semi-dry deacidification tower; 32. Bag filter; 33. CO\O2 online laser gas analyzer; 34. Front wall combustion-supporting secondary air door nozzle; 35. First nozzle; 36. Rear wall combustion-supporting secondary air door nozzle; 37. Second nozzle; 38. Electric air door D; 39. Biogas flue gas pipeline;

[0047] 40. Biogas combustion chamber; 41. Biogas auxiliary burner; 42. Biogas pipeline; 43. Biogas combustion-supporting fan; 44. Incinerator grate; 45. Drying section of the lower wind chamber of the incinerator; 46. Electric damper A; 47. Zirconia online oxygen analyzer;

[0048] 50. Incinerator; 51. Garbage inlet; 52. Slag outlet; 60. Waste heat boiler; 70. Economizer. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Depend on Figure 1 to Figure 2It is given that, on the one hand, the present invention provides a flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler, including an incinerator 50, a primary air mechanism, a waste heat boiler 60, a semi-dry deacidification tower 31, a bag dust collector 32, an induced draft fan 1, a circulating fan 6, a first nozzle 35, a second nozzle 37, a secondary fan 7, a front wall combustion-supporting secondary air valve nozzle 34, a rear wall combustion-supporting secondary air valve nozzle 36, a detection component, a low calorific value garbage burning mechanism and a biogas inlet mechanism.

[0051] Specifically, the incinerator 50 includes a garbage feed inlet 51, an incinerator grate 44, an incinerator downwind chamber drying section 45, an incinerator downwind chamber combustion and burnout section 25 and a slag discharge port 52. More specifically, the incinerator grate 44 is arranged at the lower right of the garbage feed inlet 51, the incinerator downwind chamber drying section 45 and the incinerator downwind chamber combustion and burnout section 25 are both arranged below the incinerator grate 44, and the slag discharge port 52 is arranged on the right side of the incinerator grate 44. More specifically, domestic garbage enters from the garbage feed inlet 51 to the top of the incinerator grate 44 for combustion, and the burned slag is discharged from the incinerator 50 from the slag discharge port 52.

[0052] Depend on Figures 2 to 3 It is shown that the waste heat boiler 60 is arranged above the incinerator 50, and the waste heat boiler 60 is interconnected with the incinerator grate 44. The waste heat boiler 60 includes a waste heat boiler front wall 26, a front arch water-cooled wall 29, a rear arch water-cooled wall 30, a rear wall water-cooled wall 27, a furnace top water-cooled wall 28 and an economizer 70.

[0053] Specifically, the front arch water-cooled wall 29 is arranged at the bottom of the front wall 26 of the waste heat boiler, the bottom of the front arch water-cooled wall 29 is arranged on the groove wall on the side of the garbage feed port 51, the rear arch water-cooled wall 30 is arranged on the groove wall on the side of the slag discharge port 52, the rear wall water-cooled wall 27 is arranged on the top of the rear arch water-cooled wall 30, the furnace top water-cooled wall 28 is arranged on the top of the front wall 26 and the rear wall water-cooled wall 27 of the waste heat boiler, a furnace cavity is arranged on the right side of the furnace top water-cooled wall 28 and the rear wall water-cooled wall 27, and the economizer 70 is arranged inside the furnace cavity. More specifically, the flue gas from the combustion of garbage in the grate 44 of the incinerator enters the interior of the waste heat boiler 60.

[0054] Depend on Figures 2 to 3It is given that the semi-dry deacidification tower 31 is arranged on the right side of the economizer 70, and the bag-type dust collector 32 is arranged on the right side of the semi-dry deacidification tower 31, and the economizer 70, the semi-dry deacidification tower 31, and the bag-type dust collector 32 are sequentially connected to each other through pipelines, and a draft fan connected to the flue 2 is arranged on the side of the bag-type dust collector 32 away from the semi-dry deacidification tower 31, and the input end of the induced draft fan 1 is connected to the side of the induced draft fan connected to the flue 2, and the output end of the induced draft fan 1 is connected to the chimney. Specifically, the induced draft fan 1 generates suction to draw out the flue gas in the waste heat boiler 60, and the flue gas enters the semi-dry deacidification tower 31 and the bag-type dust collector 32 in sequence through pipelines, and is then sent into the chimney through the induced draft fan 1.

[0055] Depend on Figure 1 to Figure 2 It is given that, in addition, the primary air mechanism is arranged on the trough wall below the drying section 45 of the lower air chamber of the incinerator and the combustion and burnout section 25 of the lower air chamber of the incinerator. Specifically, the primary air mechanism includes a primary air fan 8, an air preheating chamber 23, a primary air duct A22, a flue gas mixer 21, an electric regulating damper A46 and a primary air duct B24.

[0056] More specifically, the air preheating chamber 23 is arranged on one side of the primary fan 8, and the air preheating chamber 23 is interconnected with the primary fan 8 through a pipeline, the primary air duct A22 is arranged on the other side of the air preheating chamber 23, the flue gas mixer 21 is installed on the other side of the primary air duct A22, the flue gas mixer 21 is connected to the drying section 45 of the lower wind chamber of the incinerator through a pipeline, the electric regulating damper A46 is arranged at one end of the primary air duct A22 close to the flue gas mixer 21, and the end of the primary air duct A22 close to the flue gas mixer 21 is connected to the combustion and burnout section 25 of the lower wind chamber of the incinerator through the primary air duct B24; more specifically, the air provided by the primary fan 8 is heated by the air preheating chamber 23 and the flue gas mixer 21, and then sent into the drying section 45 of the lower wind chamber of the incinerator and the combustion and burnout section 25 of the lower wind chamber of the incinerator, and the heat source required for heating the air preheating chamber 23 comes from the boiler drum and the steam turbine exhaust.

[0057] Depend on Figures 2 to 3It is given that, secondly, the circulating fan 6, the first nozzle 35, the second nozzle 37 and the secondary fan 7 constitute a recirculating flue gas system. Specifically, the circulating fan 6 is interconnected with the induced draft fan 1 through the recirculating fan inlet flue 5, and an electric damper A3 is installed on one side of the recirculating fan inlet flue 5, and a bypass purge air electric damper 4 is also provided on one side of the recirculating fan inlet flue 5; a circulating fan outlet flue 9 is provided at the air outlet end of the circulating fan 6, and a front wall header 13 and a rear wall header 14 are provided on the other side of the circulating fan outlet flue 9, and an electric damper B15 is provided on one side of the circulating fan outlet flue 9, the first nozzle 35 is installed on one side of the front wall header 13, and the nozzle end of the first nozzle 35 is tilted downward and penetrated on the groove wall on one side of the front arch water-cooled wall 29, the second nozzle 37 is installed on one side of the rear wall header 14, and the nozzle end of the second nozzle 37 is tilted upward and penetrated on the groove wall on one side of the rear wall water-cooled wall 27.

[0058] More specifically, the recycled flue gas is taken from the bag filter 32 and connected to the induced draft fan flue 2, and the opening of the induced draft fan connecting flue 2 is connected to the recycling fan inlet flue 5; when the recycling system is shut down, the electric damper A3 can be closed, and the bypass purge air electric damper 4 can be started at the same time, and the negative pressure of the recycling fan 6 can be used to inhale fresh air to purge the pipeline.

[0059] When the flue gas recirculation system is activated, the flue gas in the induced draft fan connected to the flue 2 is sent into the front wall header 13 and the rear wall header 14 by the recirculation fan 6, and then sent into the furnace by the first nozzle 35 connected to the front wall header 13 and the second nozzle 37 connected to the rear wall header 14 to fully stir the high-temperature flue gas in the furnace.

[0060] The distance between the first nozzle 35 and the second nozzle 37 is usually 300 mm to 500 mm, and the specific value is determined comprehensively according to the amount of circulating flue gas, the number of nozzles, and the width of the furnace.

[0061] Depend on Figure 5 , Figure 8 and Fig. 9 It is given that, in order to improve the effective disturbance of the recycled flue gas to the high-temperature flue gas in the furnace, the nozzles of the first nozzle 35 and the second nozzle 37 are designed to be elliptical structures, and the nozzles are diffused with a diffusion angle of 17.7°. The length-to-width ratio of the inner diameter of the elliptical nozzle is 100:30, the wall thickness of the nozzle is 8mm, and the material is made of 310S material; the elliptical and diffuse nozzle can increase the coverage of the recycled flue gas when it disturbs the high-temperature flue gas in the furnace, ensure the full combustion of the volatile matter in the furnace, and reduce the generation of CO. The first nozzle 35 is tilted downward at an angle of 25° to the horizontal plane, and the second nozzle 37 is tilted upward at an angle of 25° to the horizontal plane, thereby increasing the disturbance range of the flue gas inside the crushing furnace 50.

[0062] Depend on Figure 1 and Figure 4 In addition, the secondary fan 7, the front wall combustion-supporting secondary air door nozzle 34, the rear wall combustion-supporting secondary air door nozzle 36 and the detection component constitute a combustion-supporting secondary air system. Specifically, the output end of the secondary fan 7 is equipped with a secondary fan outlet duct 10, and the outlet end of the secondary fan outlet duct 10 is provided with an air inlet header A11 and an air inlet header B12. The air inlet end of the front wall combustion-supporting secondary air door nozzle 34 is installed on one side of the air inlet header A11, and the front wall combustion-supporting secondary air door nozzle 36 is installed on the other side of the air inlet header A11. The nozzle end of 4 is tilted downward and penetrates the groove wall installed in the rear arch water-cooled wall 30, and the air inlet end of the rear wall combustion-supporting secondary air door nozzle 36 is installed on the side of the air supply header B12. At the same time, the rear wall combustion-supporting secondary air door nozzle 36 is tilted upward and penetrates the groove wall installed in the rear wall water-cooled wall 27. More specifically, the external air is delivered into the air supply header A11 and the air supply header B12 by the secondary fan 7, and then delivered into the furnace by the front wall combustion-supporting secondary air door nozzle 34 and the rear wall combustion-supporting secondary air door nozzle 36.

[0063] More specifically, a front wall combustion-supporting secondary air gate nozzle 34 and a rear wall combustion-supporting secondary air gate nozzle 36 are arranged 1000 mm above the first nozzle 35 and the second nozzle 37 of the recirculated flue gas. The nozzles of the front wall combustion-supporting secondary air gate nozzle 34 and the rear wall combustion-supporting secondary air gate nozzle 36 are both designed to be elliptical structures, and the nozzles are diffused, with a diffusion angle of 17.7°. The length-to-width ratio of the inner diameter of the elliptical nozzle is 100:30, the wall thickness of the nozzle is 8 mm, and the material is made of 310S material. The elliptical and diffuse nozzle can increase the coverage of the recirculated flue gas when disturbing the high-temperature flue gas in the furnace, ensure the full combustion of the volatile matter in the furnace, and reduce the generation of CO. The front wall combustion-supporting secondary air door nozzle 34 and the rear wall combustion-supporting secondary air door nozzle 36 are respectively connected to the air supply manifold A11 and the air supply manifold B12, and the secondary fan 7 delivers fresh air into the air supply manifold A11 and the air supply manifold B12 through the secondary fan outlet air duct 10.

[0064] Preferably, the detection assembly includes a CO\O2 online laser gas analyzer 33 and a zirconium oxide online oxygen analyzer 47. Specifically, a channel is provided at the upper end of the front wall 26 of the waste heat boiler, the CO\O2 online laser gas analyzer 33 is installed at the outlet of the channel, and the zirconium oxide online oxygen analyzer 47 is installed at the outlet of the economizer 70; more specifically, the CO\O2 online laser gas analyzer 33 and the zirconium oxide online oxygen analyzer 47 installed at the outlet of the channel can quickly and accurately detect the average concentration of gas on the laser path, which is conducive to real-time monitoring of changes in the combustion conditions of the incinerator, and timely response through the combustion control system. When the CO concentration in the furnace is high and the oxygen content is low, the secondary fan 7 can quickly adjust the operating frequency, and the primary fan 8 can also increase the frequency appropriately to ensure stable combustion and the CO concentration does not exceed the standard.

[0065] Depend on Figure 1 and Figure 4 It is given that, at the same time, the low calorific value garbage burning mechanism is installed on one side of the circulating fan outlet flue 9, and the low calorific value garbage burning mechanism includes a recycled flue gas bypass duct A17, an electric damper C16, a flue gas preheater 18, a recycled flue gas bypass duct B19 and an electric regulating damper B20.

[0066] Specifically, the recirculating flue gas bypass duct A17 is installed on one side of the circulating fan outlet flue 9, the electric damper C16 is installed on one side of the recirculating flue gas bypass duct A17, the flue gas preheater 18 is installed on the air outlet end of the recirculating flue gas bypass duct A17, the recirculating flue gas bypass duct B19 is installed on the output end of the flue gas preheater 18, the electric regulating damper B20 is installed on one side of the recirculating flue gas bypass duct B19, and the air outlet end of the recirculating flue gas bypass duct B19 is connected to and installed on one side of the flue gas mixer 21.

[0067] More specifically, when burning low calorific value garbage, the furnace temperature may be low. At this time, the introduction of recycled flue gas may cause the furnace temperature to fail to reach 850°C. Therefore, this system designs another way for recycled flue gas to enter the furnace. The electric damper B15 is closed, and the electric damper C16 and the electric regulating damper B20 are opened. The recycled flue gas is mixed with the primary air through the recycled flue gas bypass pipe A17, the flue gas preheater 18, and the flue gas mixer 21 in turn and is sent to the drying section 45 of the lower wind chamber of the incinerator. The flue gas preheater 18 can heat the recycled flue gas temperature to 220-250°C, which can prevent the flue gas from corroding the drying section 45 of the lower wind chamber of the incinerator at low temperature. The heating heat source comes from the steam from the drum or the first extraction of the steam turbine.

[0068] The recycled flue gas is sent into the drying section 45 of the lower wind chamber of the incinerator to replace part of the primary hot air, thereby enhancing the drying of the garbage and, at the same time, saving the amount of steam extracted by the primary air heating.

[0069] Depend on Figure 1 and Figure 4 Finally, as a supplement to the flue gas recirculation low NOx combustion system, the traditional way of feeding biogas into the furnace is to send the biogas into the garbage pool and enter the furnace with the primary air; or to send the biogas into the furnace after burning in a biogas burner; although these two methods do not waste energy, they do not give full play to the functionality of biogas entering the furnace.

[0070] The biogas inlet mechanism is arranged on one side of the flue gas mixer 21, and comprises a biogas auxiliary burner 41, a biogas combustion chamber 40, a biogas pipeline 42, a biogas combustion auxiliary blower 43, a biogas flue gas pipeline 39 and an electric damper D38.

[0071] Specifically, the biogas pipeline 42 is arranged at the input end on the right side of the biogas auxiliary burner 41, the biogas combustion-supporting fan 43 is arranged on one side of the biogas pipeline 42, the biogas combustion chamber 40 is arranged at the output end on the left side of the biogas auxiliary burner 41, the biogas smoke pipeline 39 is arranged at the gas transmission end on the left side of the biogas combustion chamber 40, the electric damper D38 is arranged on one side of the biogas smoke pipeline 39, and one side of the biogas smoke pipeline 39 is connected and installed in the flue gas mixer 21; more specifically, the biogas from the leachate treatment station is sent to the biogas combustion chamber 40 for combustion, and the biogas combustion chamber 40 is equipped with a separate biogas combustion-supporting fan 43. The flue gas after combustion passes through the biogas smoke pipeline 39, is sent to the flue gas mixer 21 to mix with the primary air, and then sent to the drying section 45 of the lower wind chamber of the incinerator. When the recycled flue gas and the biogas combustion flue gas enter the drying section 45 of the lower wind chamber of the incinerator at the same time, the electric damper A46 can be adjusted to flexibly adjust the primary air volume entering the drying section 45 of the lower wind chamber of the incinerator.

[0072] The high-temperature biogas smoke after combustion is sent to the drying section 45 of the lower wind chamber of the incinerator to replace part of the primary hot air, thereby enhancing the drying of the garbage and saving the amount of steam extracted by the primary air heating.

[0073] Better yet, the recirculation fan inlet flue 5, the circulation fan outlet flue 9, the recirculation flue gas bypass duct A17 and the recirculation flue gas bypass duct B19 are all FRP ventilation ducts. The FRP ventilation ducts have strong resistance to acid and alkali corrosion, and the operating temperature is less than 250°C, which meets the use requirements of the recirculation flue gas ducts. At the same time, the FRP ventilation pipes are light in weight and easy to install. The ducts are installed obliquely along the direction of flue gas forward, with an inclination of not less than one thousandth. A drain valve is set at the lowest point of the duct to automatically discharge condensate, air and carbon dioxide gas, while preventing steam leakage to the maximum extent.

[0074] In summary, embodiment 1:

[0075] Garbage is burned on the grate 44 of the incinerator. The air required for combustion mainly comes from the primary air sent by the primary fan 8. In addition, the air sent into the furnace by the secondary fan 7 is used as auxiliary air to promote the mixing of the furnace flue gas and the full combustion of volatiles. The excess air coefficient of the primary air is controlled at λ=1.1-1.27, and the excess air coefficient of the secondary air is controlled at λ=0.23-0.13, so as to keep the combustion on the grate 44 of the incinerator in a relatively oxygen-deficient state and suppress the generation of fuel-type NOx. At this time, the electric damper C16 is closed, and the recirculated flue gas is only sent to the front wall header 13 and the rear wall header 14, and enters the furnace from the connected first nozzle 35 and the second nozzle 37, so as to fully disturb and mix the flue gas and promote the combustion of volatiles. The new first nozzle 35 and second nozzle 37 have a diffusion effect, and the disturbance coverage of the furnace flue gas is wider. Compared with the traditional nozzle, the disturbance effect on the furnace flue gas is better; the front wall combustion-supporting secondary air door nozzle 34 and the rear wall combustion-supporting secondary air door nozzle 36 also use the same nozzle to ensure that the fresh air of the supplementary combustion can be fully mixed with the flue gas. After the recycled flue gas and the supplementary combustion secondary air are sent into the furnace, the local temperature of the furnace can be reduced and the generation of thermal NOx can be suppressed. The CO\O2 online laser gas analyzer 33 installed at the outlet of the first channel of the furnace monitors the changes in the concentration of CO and O2 in the furnace in real time to ensure the stability of the combustion conditions.

[0076] This low NOx combustion method achieves the goal of low excess air ratio and low NOx generation by using the technical means of relatively underoxygenated combustion + air staged combustion + sufficient mixing disturbance to reduce the local furnace temperature.

[0077] Some studies in the industry have further reduced the primary air excess air coefficient λ to 0.9-1 to maintain absolute under-oxygen combustion. This solution is difficult to implement in practice. Unlike pulverized coal furnaces, the burning of garbage on the grate is layered combustion, which requires more oxygen. When the primary air excess air coefficient λ is further reduced to the range of 0.9-1, it will lead to incomplete combustion, the risk of raw materials and furnace temperature not dropping to 850℃. When implementing flue gas recirculation low NOx combustion, the stability of the incinerator 50 combustion, furnace temperature, and slag heat reduction rate must be given priority.

[0078] Embodiment 2:

[0079] When burning low calorific value garbage, or a large amount of leachate is sprayed back into the furnace, resulting in a low furnace temperature, the recycled flue gas will not be directly sent into the furnace, but will be sent to the drying section 45 of the lower wind chamber of the incinerator to strengthen the drying of the garbage and promote combustion; at this time, the primary air excess air coefficient is controlled at λ=1.1-1.27, and the secondary air excess air coefficient is controlled at λ=0.23-0.13; a CO\O2 online laser gas analyzer 33 installed at the outlet of the first channel of the furnace monitors the CO and O2 concentrations in the furnace in real time. When O2 is low and the CO concentration deviates from the design value, the primary / secondary air input is increased in time to ensure stable combustion.

[0080] The specific operation method is to close the electric damper B15, open the electric damper C16 and the electric regulating damper B20, and the recycled flue gas passes through the recycled flue gas bypass pipe A17, the flue gas preheater 18 and the flue gas mixer 21 in sequence, and is mixed with the primary air and then sent to the drying section 45 of the lower wind chamber of the incinerator. The flue gas preheater 18 can heat the recycled flue gas temperature to 220-250℃, which can prevent the flue gas from corroding the drying section 45 of the lower wind chamber of the incinerator at low temperature. The heating heat source comes from the steam extracted from the steam drum or the steam turbine.

[0081] The recycled flue gas is sent into the drying section 45 of the lower wind chamber of the incinerator to replace part of the primary hot air, thereby enhancing the drying of the garbage and, at the same time, saving the amount of steam extracted by the primary air heating.

[0082] Embodiment three:

[0083] While the flue gas recirculation system is running, the biogas from the leachate treatment station is sent to the biogas combustion chamber 40 for combustion. The biogas auxiliary burner 41 is equipped with a separate biogas combustion auxiliary fan 43, which is installed in the biogas combustion chamber 40. The flue gas after combustion passes through the biogas flue gas duct 39, is sent to the flue gas mixer 21 to be mixed with the primary air, and then sent to the drying section 45 of the lower wind chamber of the incinerator; when the recycled flue gas and the biogas combustion flue gas enter the drying section 45 of the lower wind chamber of the incinerator at the same time, the electric regulating damper A46 can be adjusted to flexibly adjust the primary air volume entering the drying section 45 of the lower wind chamber of the incinerator.

[0084] This method of feeding biogas into the furnace fully utilizes the functionality of biogas combustion heat, strengthens garbage drying and promotes combustion; at the same time, the high-temperature biogas smoke after combustion is sent to the drying section 45 of the lower wind chamber of the incinerator to replace part of the primary hot air, saving the amount of primary air heating steam extraction.

[0085] On the other hand, the present invention provides a method for using a flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler, including the following method: the waste enters the incinerator grate 44 from the waste feed port 51 for combustion, and the incinerator flue gas exits the waste heat boiler and enters the semi-dry deacidification tower 31, the bag filter 32, the induced draft fan connected flue 2 and the induced draft fan 1 in sequence under the suction force of the induced draft fan 1 and is sent into the chimney;

[0086] Primary air: The air provided by the primary fan 8 is heated in the air preheating chamber 23 and sent to the drying section 45 of the lower wind chamber of the incinerator and the combustion section 25 of the lower wind chamber of the incinerator after being mixed by the flue gas mixer 21. The heat source required for heating the air preheating chamber 23 comes from the boiler drum and the first extraction of the steam turbine;

[0087] Recirculating flue gas: close the electric damper C16, and the recirculating flue gas is sent into the furnace front wall header 13 and the rear wall header 14 through the circulating fan 6, and then sent into the furnace through the first nozzle 35 and the second nozzle 37 to fully stir the high-temperature flue gas in the furnace. When the recirculating system stops operating, close the electric damper A3, and start the bypass purge air electric damper 4 at the same time, and use the negative pressure of the circulating fan 6 to inhale fresh air to purge the pipeline;

[0088] Combustion-supporting secondary air: The secondary fan 7 delivers air to the air supply header A11 and the air supply header B12 through the secondary fan outlet duct 10, and then delivers the air into the furnace through the front wall combustion-supporting secondary air door nozzle 34 and the rear wall combustion-supporting secondary air door nozzle 36. The CO\O2 online laser gas analyzer 33 and the zirconium oxide online oxygen analyzer 47 detect the average gas concentration. When the CO concentration in the furnace is high and the oxygen content is low, the secondary fan 7 quickly adjusts the operating frequency and the primary fan 8 appropriately increases the frequency to ensure stable combustion and the CO concentration does not exceed the standard;

[0089] Burning low calorific value garbage: close the electric damper B15, open the electric damper C16 and the electric regulating damper B20, the recycled flue gas passes through the recycled flue gas bypass duct A17, the flue gas preheater 18 and the flue gas mixer 21 in sequence, and is mixed with the primary air and then sent to the drying section 45 of the lower wind chamber of the incinerator. Then the flue gas preheater 18 heats the recycled flue gas to a temperature of 220-250°C. The heating heat source comes from the steam from the drum or the first extraction of the steam turbine.

[0090] Biogas enters the furnace: biogas is sent to the biogas combustion chamber 40 for combustion, and the biogas auxiliary burner 41 is equipped with a separate biogas combustion auxiliary fan 43. The flue gas after combustion is sent to the flue gas mixer 21 through the biogas flue gas duct 39 to be mixed with the primary air, and finally sent to the drying section 45 of the lower wind chamber of the incinerator; when the recycled flue gas and the biogas combustion flue gas enter the drying section 45 of the lower wind chamber of the incinerator at the same time, the electric regulating damper A46 is adjusted to control the primary air volume entering the drying section 45 of the lower wind chamber of the incinerator.

[0091] The beneficial effects obtained by the incinerator 50, the primary air mechanism, the waste heat boiler 60, the semi-dry deacidification tower 31, the bag filter 32, the induced draft fan 1, the circulating fan 6, the first nozzle 35, the second nozzle 37, the secondary fan 7, the front wall combustion-supporting secondary air door nozzle 34, the rear wall combustion-supporting secondary air door nozzle 36, the detection component, the low calorific value garbage combustion mechanism and the biogas furnace entry mechanism are as follows: the flue gas recirculation combined with low oxygen combustion can improve the boiler efficiency and increase the boiler evaporation. The flue gas recirculation low NOx combustion can reduce the original nitrogen oxide generation by about 30%, save the use of the back-end denitrification agent, and reduce the production cost; at the same time, it reduces the pressure of the back-end denitrification system, and is also conducive to controlling the nitrogen oxide emission concentration and ammonia escape at a lower level. The flue gas after the biogas combustion is sent to the primary air for mixing, and then sent to the drying section of the lower wind chamber of the incinerator to dry the garbage, which gives full play to the functionality of the biogas combustion heat energy and can reduce the steam consumption of the primary air preheater. The recycled flue gas is sent to the lower wind chamber of the incinerator to dry the garbage, which enhances the adaptability of the flue gas recirculation system to the combustion of low calorific value garbage and can reduce the steam consumption of the primary air preheater. The implementation of flue gas recirculation can enhance the reducing atmosphere of the furnace and slow down the high temperature corrosion of the heating surface in the furnace. At the same time, the reduction of the local temperature of the furnace brought about by flue gas recirculation can also slow down the coking of the furnace.

[0092] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler, characterized in that: It comprises an incinerator (50), wherein a primary air mechanism is provided on one side of the incinerator (50); A waste heat boiler (60) is disposed on one side of the incinerator (50), a semi-dry deacidification tower (31) is disposed on one side of the waste heat boiler (60), a bag filter (32) is disposed on one side of the semi-dry deacidification tower (31), and an induced draft fan (1) is disposed on one side of the bag filter (32); A circulation fan (6) is arranged on one side of the induced draft fan (1), and a first nozzle (35) and a second nozzle (37) are arranged on one side of the circulation fan (6), the first nozzle (35) being arranged obliquely downward on one side of the waste heat boiler (60), and the second nozzle (37) being arranged obliquely upward on one side of the waste heat boiler (60), a secondary fan (7) is arranged on one side of the waste heat boiler (60), and a front wall combustion-supporting secondary air gate nozzle (34) and a rear wall combustion-supporting secondary air gate nozzle (36) are arranged at the output end of the secondary fan (7), the front wall combustion-supporting secondary air gate nozzle (34) being arranged obliquely downward on one side of the waste heat boiler (60), and the rear wall combustion-supporting secondary air gate nozzle (36) being arranged obliquely upward on one side of the waste heat boiler (60), and a detection component is installed on one side of the waste heat boiler (60); A low calorific value garbage burning mechanism is provided between the circulating fan (6) and the incinerator (50); A biogas inlet mechanism is also provided on one side of the incinerator (50).

2. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 1 is characterized in that: The waste heat boiler (60), the semi-dry deacidification tower (31) and the bag filter (32) are interconnected via a smoke path in sequence; an induced draft fan connected to a smoke duct (2) is provided on the side of the bag filter (32) facing away from the semi-dry deacidification tower (31); and an induced draft fan (1) is provided on the other side of the induced draft fan connected to the smoke duct (2).

3. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 2 is characterized in that: The incinerator (50) comprises a garbage feed port (51), an incinerator grate (44) is arranged on one side of the garbage feed port (51), an incinerator downwind chamber drying section (45) is arranged on one side of the incinerator grate (44), an incinerator downwind chamber combustion and burnout section (25) is arranged on one side of the incinerator downwind chamber combustion and burnout section (25), and a slag discharge port (52) is arranged on one side of the incinerator downwind chamber combustion and burnout section (25).

4. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 3 is characterized in that: The primary air mechanism comprises a primary air fan (8), an air preheating chamber (23) is arranged at the air outlet end of the primary air fan (8) through a pipeline, a flue gas mixer (21) is arranged at the air outlet end of the air preheating chamber (23) through a primary air duct A (22), the air outlet end of the flue gas mixer (21) is connected to a drying section (45) of a lower air chamber of the incinerator through a pipeline, an electric regulating damper A (46) is arranged at one end of the primary air duct A (22) close to the flue gas mixer (21), and a middle part of the primary air duct A (22) is connected to a combustion and burnout section (25) of a lower air chamber of the incinerator through a primary air duct B (24).

5. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 4 is characterized in that: The induced draft fan (1) and the circulating fan (6) are connected to each other via a recirculating fan inlet flue (5); an electric damper A (3) is provided on one side of the recirculating fan inlet flue (5); a bypass purge air electric damper (4) is also provided on one side of the recirculating fan inlet flue (5) via a pipeline; a circulating fan outlet flue (9) is provided at the air outlet end of the circulating fan (6); an electric damper B (15) is provided on one side of the circulating fan outlet flue (9); a front wall header (13) and a rear wall header (14) are provided at the air outlet end of the circulating fan outlet flue (9); One end of the front wall header (13) is connected and installed on the first nozzle (35), and one end of the rear wall header (14) is connected and installed on the second nozzle (37). A secondary fan outlet duct (10) is provided on one side of the secondary fan (7), and an air inlet header A (11) and an air inlet header B (12) are provided at the air outlet end of the secondary fan outlet duct (10). One side of the air inlet header A (11) is installed on the air inlet end of the front wall combustion-supporting secondary air valve nozzle (34), and the air inlet header B (12) is connected and installed on the air inlet end of the rear wall combustion-supporting secondary air valve nozzle (36).

6. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 5 is characterized in that: The waste heat boiler (60) comprises a waste heat boiler front wall (26), a front arch water-cooled wall (29) is arranged at the bottom of the waste heat boiler front wall (26), the front arch water-cooled wall (29) is arranged on one side of a garbage feed port (51), a rear arch water-cooled wall (30) is arranged on one side of a slag discharge port (52), a rear wall water-cooled wall (27) is arranged on the top of the rear arch water-cooled wall (30), a furnace top water-cooled wall (28) is arranged on the top of the waste heat boiler front wall (26), a furnace cavity is arranged on one side of the furnace top water-cooled wall (28) and the rear wall water-cooled wall (27), and an economizer (70) is arranged inside the furnace cavity.

7. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 6 is characterized in that: The detection component comprises a CO\O2 online laser gas analyzer (33) installed on one side of the front wall (26) of the waste heat boiler, and a zirconium oxide online oxygen analyzer (47) is installed at the outlet of the economizer (70).

8. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 5 is characterized in that: The low calorific value garbage burning mechanism comprises a recirculating flue gas bypass pipe A (17) arranged at one side of the circulating fan outlet flue (9), an electric damper C (16) is arranged at one side of the recirculating flue gas bypass pipe A (17), a flue gas preheater (18) is arranged at the gas outlet end of the recirculating flue gas bypass pipe A (17), the flue gas preheater (18) is connected to the flue gas mixer (21) through the recirculating flue gas bypass pipe B (19), and an electric regulating damper B (20) is arranged at one side of the recirculating flue gas bypass pipe B (19); The recirculation fan inlet flue (5), the circulation fan outlet flue (9), the recirculation flue gas bypass duct A (17) and the recirculation flue gas bypass duct B (19) are all glass fiber reinforced plastic ventilation ducts.

9. The flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler according to claim 6 is characterized in that: The biogas inlet mechanism comprises a biogas combustion chamber (40), a biogas auxiliary burner (41) is arranged on one side of the biogas combustion chamber (40), a biogas pipeline (42) is arranged on one side of the biogas auxiliary burner (41), a biogas combustion-supporting blower (43) is arranged on one side of the biogas pipeline (42), the biogas combustion chamber (40) is connected to the flue gas mixer (21) via a biogas smoke pipeline (39), and an electric damper D (38) is arranged on one side of the biogas smoke pipeline (39).

10. A method for using a flue gas recirculation system for improving the performance of a domestic waste incineration power generation boiler, according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: garbage enters the top of the incinerator grate (44) from the garbage feed port (51) for combustion; smoke from the incinerator exits the waste heat boiler and, under the suction of the induced draft fan (1), enters the semi-dry deacidification tower (31), the bag filter (32), the induced draft fan connecting flue (2) and the induced draft fan (1) in sequence and is sent into the chimney; Primary air: The air provided by the primary fan (8) is heated by the air preheating chamber (23) and the flue gas mixer (21), and then sent to the drying section (45) of the lower wind chamber of the incinerator and the combustion and burning section (25) of the lower wind chamber of the incinerator. The heat source required for heating the air preheating chamber (23) comes from the boiler drum and the first extraction of the steam turbine; Recirculating flue gas: close the electric damper C (16), and the recirculating flue gas is sent into the furnace front wall header (13) and the rear wall header (14) through the circulating fan (6), and then sent into the furnace through the first nozzle (35) and the second nozzle (37), so as to fully stir the high-temperature flue gas in the furnace. When the recirculating system stops operating, close the electric damper A (3), and start the bypass purge air electric damper (4) at the same time, and use the negative pressure of the circulating fan (6) to inhale fresh air to purge the pipeline; Combustion-supporting secondary air: The secondary fan (7) delivers air to the air inlet header A (11) and the air inlet header B (12) through the secondary fan outlet duct (10), and then delivers the air into the furnace through the front wall combustion-supporting secondary air door nozzle (34) and the rear wall combustion-supporting secondary air door nozzle (36). The CO\O2 online laser gas analyzer (33) and the zirconium oxide online oxygen analyzer (47) detect the average gas concentration. When the CO concentration in the furnace is too high and the oxygen content is too low, the secondary fan (7) quickly adjusts the operating frequency and the primary fan (8) appropriately increases the frequency to ensure stable combustion and that the CO concentration does not exceed the standard. Burning low calorific value garbage: close the electric damper B (15), open the electric damper C (16) and the electric regulating damper B (20), and the recycled flue gas passes through the recycled flue gas bypass duct A (17), the flue gas preheater (18) and the flue gas mixer (21) in sequence, and is mixed with the primary air and then sent to the drying section (45) of the lower wind chamber of the incinerator. Then the flue gas preheater (18) heats the recycled flue gas to a temperature of 220-250°C. The heating heat source comes from the steam from the drum or the first extraction of the steam turbine. Biogas entering the furnace: Biogas is sent to the biogas combustion chamber (40) for combustion. The biogas auxiliary burner (41) is equipped with a separate biogas auxiliary blower (43). The smoke after combustion is sent to the smoke mixer (21) through the biogas smoke pipe (39) to mix with the primary air, and finally sent to the drying section (45) of the lower wind chamber of the incinerator. When the recycled smoke and the biogas combustion smoke enter the drying section (45) of the lower wind chamber of the incinerator at the same time, the electric regulating damper A (46) is adjusted to control the primary air volume entering the drying section (45) of the lower wind chamber of the incinerator.

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