A combustion system and method suitable for flexible peak regulation of tangentially-shaped boilers

Abstract

The present invention discloses a combustion system and method adapted for flexible peak regulation of a four-corner tangential boiler. The combustion system adapted for flexible peak regulation of a four-corner tangential boiler comprises a furnace, five layers of DC burners and swirl burners. The five layers of DC burners are, from bottom to top, a first layer of DC burners, a second layer of DC burners, a third layer of DC burners, a fourth layer of DC burners and a fifth layer of DC burners. Each layer of the DC burners comprises four DC burners arranged at the four corners of the furnace. The DC burners have a primary air channel. At least one layer of the DC burners is a stable combustion DC burner layer. A swirl burner is provided in the primary air channel of each of the four DC burners in the stable combustion DC burner layer. The combustion system and method adapted for flexible peak regulation of a four-corner tangential boiler according to the embodiment of the present invention have the advantages of low construction difficulty, short construction period, low transformation cost and low operating cost.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power station boilers, and in particular to a combustion system and method suitable for flexible peak regulation of tangentially-intersecting boilers. Background Art

[0002] In 2021, China's total power generation reached 8,112.2 billion kWh, of which thermal power generation reached 5,745 billion kWh, accounting for 70.8%. Thermal power generation, primarily based on coal-fired units, is the foundation and ballast of my country's electric energy supply, and its importance is self-evident.

[0003] Deep peak shaving for coal-fired power plant boilers refers to operating the boiler at a minimum load below 35% of rated load. The basic requirement is stable combustion at low loads. A second-level requirement is efficient combustion, with high pulverized coal combustion efficiency. A third-level requirement is maintaining low initial emissions of pollutants such as NOx. These three requirements represent the technical challenges of deep peak shaving for coal-fired power plant boilers. However, current coal-fired power plant boilers cannot meet the first level of requirements due to the frequent fluctuations in incoming coal quality and the inadequate low-load combustion stability of burners. Therefore, improving the low-load combustion stability of coal-fired power plant boilers has become a key focus of technical improvements for coal-fired power plants.

[0004] The invention patent application number 202011045487.7, "A combustion system and method suitable for flexible peak regulation of four-corner tangential boilers", discloses that a layer of swirl burner burning high-quality bituminous coal powder is arranged between two layers of direct current burners. The advantages of the swirl burner's strong ability to absorb high-temperature flue gas and better self-stabilizing combustion ability are used to solve the problem of low-load stable combustion.

[0005] Patent application number 202110175350.1, "Combustion System and Combustion Method with Precombustion Chamber Burners on Both Sides of a Boiler," discloses swirl burners with precombustion chambers placed on the boiler side walls. Primary air is used to transport high-concentration pulverized coal into the swirl burners. When the power plant boiler requires deep peak shaving, the swirl burners are activated.

[0006] The utility model patent application number CN201420586490.3 is "A burner arrangement structure combining double tangential circle and counter-hedge for power station boilers". The application discloses that the two arrangements of counter-hedge and tangential circle are applied to power station boilers, which can solve the problems of combustion stability, low economy and high NOx emissions of large-capacity generator set boilers.

[0007] Power plant boilers have a large number of components but are technologically mature. The actual power plant boiler equipment and piping layout is compact and has an industrial aesthetic. The inventors analyzed existing related patents and found that flexible peak-shaving technologies can be categorized as direct and indirect combustion stabilization. Direct combustion stabilization involves installing a precombustion chamber burner in the furnace, burning high-quality bituminous coal. The flame from the precombustion chamber maintains stable combustion in the direct current burner. This requires pipework to be removed from the furnace water-cooled wall. In practice, the precombustion chamber burner is heavy and difficult to deploy, resulting in complex modifications and a long construction period. Indirect combustion stabilization involves gasifying fuels such as coal and biomass, converting the solid fuel into a gaseous fuel that is then fed into the burner. This technology is costly and challenging to implement, placing higher demands on the existing power plant boiler system site and piping layout. The fundamental cause of these issues stems from a design flaw: the inventors envisioned installing a separate combustion system in addition to the existing power plant boiler system. When the power plant boiler needs to operate at low load, the newly installed combustion system can be operated, while the existing system is shut down. Under the guidance of this idea, the total power of the new combustion system is generally 20% to 40% of the thermal power of the original power station boiler system, resulting in a larger size of the single swirl precombustion chamber burner, high manufacturing and installation costs, which is not conducive to on-site construction. In the current situation where coal-fired power is generally in the red, the promotion and application of the system is more difficult. Summary of the Invention

[0008] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0009] To this end, an embodiment of the present invention proposes a combustion system that has low construction difficulty and short construction period and is suitable for flexible peak regulation of tangentially fired boilers.

[0010] The embodiment of the present invention provides a combustion method with high working reliability and suitable for flexible peak regulation of tangentially-circular boilers.

[0011] The combustion system of the embodiment of the present invention is suitable for flexible peak regulation of four-corner cut-circle boilers, and is characterized in that it includes a furnace, five layers of DC burners and swirl burners, and the five layers of DC burners are arranged at intervals in the upper and lower directions of the furnace. The five layers of DC burners are, from bottom to top, the first layer of DC burners, the second layer of DC burners, the third layer of DC burners, the fourth layer of DC burners and the fifth layer of DC burners. Each layer of the DC burners includes four DC burners respectively arranged at the four corners of the furnace, and the DC burners have a primary air channel; the number of the swirl burners is four or more, and at least one layer of the DC burners is a stable combustion DC burner layer, and a swirl burner is provided in the primary air channel of the four DC burners in the stable combustion DC burner layer.

[0012] The combustion system adapted for flexible peak regulation of four-corner cut-circle boilers in the embodiment of the present invention sets at least one layer of DC burners as a stable combustion DC burner layer, and provides a swirl burner in the primary air channel of each of the four DC burners in the stable combustion DC burner layer, so as to preheat and ignite the pulverized coal airflow in the primary air channel of the DC burner, thereby preventing the DC burner from unstable ignition when operating at low load. The combustion system adapted for flexible peak regulation of four-corner cut-circle boilers in the embodiment of the present invention only needs to install the swirl burner in the primary air channel of the DC burner. Compared with the related art in which a swirl burner is added to the boiler furnace and pipe treatment of the furnace water-cooled wall is required, since there are no complex components in the primary air channel of the DC burner, the combustion system adapted for flexible peak regulation of four-corner cut-circle boilers in the embodiment of the present invention does not require major changes to the primary air channel of the DC burner during construction and installation, thereby greatly reducing the construction difficulty and construction period.

[0013] Therefore, the combustion system adapted for flexible peak regulation of tangentially-shaped boilers according to the embodiment of the present invention has the advantages of low construction difficulty and short construction period.

[0014] In some embodiments, the swirl burner includes an air guide tube, an air powder tube, a cyclone and a return cap. The outlet end of the air guide tube is placed in the primary air channel. The air powder tube and the air guide tube are spaced apart in the radial direction of the air powder tube. The outlet end of the air powder tube is placed in the air guide tube. The cyclone is provided on the air powder tube. The outlet end of the cyclone is connected with the air guide tube. The boiler has an air duct. The inlet end of the cyclone is connected with the secondary air box of the boiler through the air duct. The cyclone is used to rotate the air at 300℃ to 400℃ in the air duct and input it into the air guide tube. A secondary air valve is provided between the cyclone and the secondary air box. The secondary air valve is used to adjust the secondary air flow entering the cyclone. The return cap is provided in the air guide tube and at the outlet end of the air powder tube. The return cap and the air powder tube are spaced apart in the axial direction of the air powder tube.

[0015] In some embodiments, the ratio of the diameter of the outlet end of the air guide tube to the height of the primary air channel is 0.3 to 0.8.

[0016] In some embodiments, the air guide tube is a conical tube, and the diameter of the air guide tube gradually decreases from the outlet end of the air guide tube to the inlet end of the air guide tube.

[0017] In some embodiments, the ratio of the maximum diameter of the flame that can be ejected by the swirl burner to the equivalent diameter of the primary air channel is 0.5-1.0; and / or the speed of the flame that can be ejected by the swirl burner is greater than 30 m / s.

[0018] In some embodiments, the ratio of the power of a single swirl burner to the power of a single direct current burner is 0.1 to 0.5.

[0019] In some embodiments, the combustion system adapted for flexible peak load regulation of a tangentially-circular boiler according to the present invention includes five coal mills, a first blower, and a pulverized coal conveying system.

[0020] The five coal mills correspond one-to-one to the five layers of DC burners, each of the coal mills is connected to the primary air channels of the four DC burners in the corresponding DC burner layer, and the first fan is connected to the five coal mills so that the primary air delivered by the first fan blows the pulverized coal in the coal mills into the corresponding primary air channels;

[0021] The powder conveying system includes a powder storage bin, a powder feeding bin, a powder conveying pipe, a discharger, a powder feeder and a second fan. The powder storage bin is connected to the powder feeding bin through the discharger, the powder feeding bin is connected to the powder conveying pipe through the powder feeder, the powder conveying pipe is connected to the inlet end of the air-powder pipe of each swirl burner, and the air outlet of the second fan is connected to the powder conveying pipe, so that the fuel in the powder feeding bin is transported to the air-powder pipe through the powder conveying pipe.

[0022] The combustion method adapted for flexible peak regulation of a tangentially-interconnected boiler according to an embodiment of the present invention is based on the combustion system adapted for flexible peak regulation of a tangentially-interconnected boiler according to any of the above embodiments, and includes:

[0023] When the boiler needs to operate under rated load, the swirl burner is in a shutdown state, and the direct current burners in each layer are in an operating state;

[0024] When the boiler needs deep peak regulation to reduce the operating load, the swirl burners in at least one layer of the stable combustion direct current burner layer are first started, and then, in order from top to bottom, the direct current burner layers other than at least a part of the stable combustion direct current burner layer in which the swirl burners are started are shut down, that is, the coal mills corresponding to the direct current burner layers to be shut down are shut down;

[0025] When the deep peak regulation of the boiler is completed and the boiler operating load needs to be restored, the DC burners in the DC burner layer that need to be operated are determined and started in order from bottom to top according to the boiler operating load requirements, that is, the coal mill corresponding to the DC burner layer is started. When the boiler operating load reaches more than 50% of the rated load, all the swirl burners can be shut down or continue to operate.

[0026] The embodiment of the present invention is suitable for a combustion method for flexible peak regulation of a tangentially-circular boiler and has advantages such as high working reliability.

[0027] In some embodiments, the combustion method adapted for flexible peak load regulation of a tangentially-circular boiler according to an embodiment of the present invention includes:

[0028] When the boiler is performing deep peak regulation and the four swirl burners in the stable combustion DC burner layer are ignited and started, first, the second fan is started, and the powder feeder is kept in a shutdown state. The primary air generated by the second fan blows the air-powder pipe of one of the swirl burners in the stable combustion DC burner layer for 1 minute to 3 minutes, and after the primary air pressure is stabilized, the second fan is stopped; secondly, the secondary air valve of the swirl burner is started with an opening of 5% to 10%, and the second fan is started. After stabilization for 30 seconds to 60 seconds, the ignition oil gun of the swirl burner is started to observe the stability of the fuel flame; then, the powder feeder is started to make the powder feed bin The fuel in the swirl burner is transported to the swirl burner under the action of the second blower and ignited by the fuel flame, and the secondary air valve opening of the swirl burner and the frequency of the powder feeder are increased. The frequency of the powder feeder will no longer increase after reaching the rated power. At the same time, the secondary air valve will no longer increase after reaching the preset opening. The amount of swirl secondary air is designed according to the excess air coefficient ≯1, so as to ensure that the flame is rich in reducing atmosphere such as CO, H2, CH4, etc., and reduce NOx generation; finally, according to the same method, the remaining three swirl burners are ignited in turn, and after waiting for the four swirl burners to be fully ignited, the ignition oil guns of the four swirl burners are stopped to stop the oil combustion.

[0029] In some embodiments, a combustion method adapted for flexible peak regulation of a tangentially-interconnected boiler according to an embodiment of the present invention is based on a combustion system adapted for flexible peak regulation of a tangentially-interconnected boiler according to any of the above embodiments, and includes:

[0030] When the fuel with a calorific value of 2000kcal / kg to 4000kcal / kg is introduced into the air-powder tube, the swirl intensity of the cyclone is 0.6 to 1.0;

[0031] When the fuel with a calorific value of 3500kcal / kg to 5000kcal / kg is introduced into the air-powder pipe, the swirl intensity of the cyclone is 0.6 to 3.0;

[0032] When fuel with a calorific value greater than or equal to 5000 kcal / kg is introduced into the air-powder tube, the swirl intensity of the swirl burner is less than or equal to 0.6. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of a combustion system suitable for flexible peak regulation of a tangentially fired boiler according to an embodiment of the present invention.

[0034] Figure 2 yes Figure 1 yes Figure 1 Cross-sectional view of AA in the figure.

[0035] Reference numerals:

[0036] Combustion system 100 adapted for flexible peak load regulation of tangentially operated boilers;

[0037] DC burner 1; first layer DC burner 101; second layer DC burner 102; third layer DC burner 103; fourth layer DC burner 104; fifth layer DC burner 105; primary air channel 106; secondary air channel 107;

[0038] Swirl burner 2; air guide tube 201; air powder tube 202; swirler 203; backflow cap 204;

[0039] First coal mill 301; second coal mill 302; third coal mill 303; fourth coal mill 304; fifth coal mill 305;

[0040] Powder conveying system 4; powder storage bin 401; powder feeding bin 402; powder conveying pipe 403; second fan 404; discharger 405; powder feeder 406;

[0041] The first fan 5. DETAILED DESCRIPTION

[0042] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0043] The technical solution of the present application is described in detail below with reference to the accompanying drawings.

[0044] like Figure 1 and Figure 2 As shown, the combustion system 100 adapted for flexible peak regulation of a four-corner tangentially-shaped boiler according to an embodiment of the present invention comprises a furnace (not shown), five layers of DC burners and a swirl burner 2. The five layers of DC burners are arranged at intervals in the vertical direction of the furnace. The five layers of DC burners are, from bottom to top, a first layer of DC burners 101, a second layer of DC burners 102, a third layer of DC burners 103, a fourth layer of DC burners 104 and a fifth layer of DC burners 105. Each layer of DC burners includes four DC burners respectively arranged at the four corners of the furnace, and the DC burners have a primary air channel 106.

[0045] The number of swirl burners 2 is four or more, and at least one layer of DC burners is a stable combustion DC burner layer, and each of the four DC burners in the stable combustion DC burner layer has a swirl burner 2 in the primary air duct 106. In other words, the first, second, third, fourth, or fifth layer of DC burners 105 in the five-layer DC burner layer can be a stable combustion DC burner layer, or multiple layers of DC burners in the five-layer DC burner layer can be a stable combustion DC burner layer, and only the four DC burners in the stable combustion DC burner layer have a swirl burner 2 in the primary air duct 106.

[0046] During use, the combustion system 100 of the embodiment of the present invention, which is suitable for flexible peak regulation of a tangentially ...

[0047] Thus, the combustion system 100 adapted for flexible peak regulation of a four-corner tangential boiler according to the embodiment of the present invention sets at least one layer of DC burners as a stable combustion DC burner layer, and provides a swirl burner 2 in the primary air duct 106 of each of the four DC burners in the stable combustion DC burner layer, thereby preheating and igniting the pulverized coal airflow in the primary air duct 106 of the DC burner, thereby preventing the DC burner from unstable ignition when operating at low load. As a result, the combustion system 100 adapted for flexible peak regulation of a four-corner tangential boiler according to the embodiment of the present invention only needs to install the swirl burner 2 in the primary air duct 106 of the DC burner. Compared with the related art, in which the installation of a swirl burner 2 on the boiler furnace requires pipe processing of the furnace water-cooled wall, since the primary air duct 106 of the DC burner does not have complex components, the combustion system 100 adapted for flexible peak regulation of a four-corner tangential boiler according to the embodiment of the present invention does not need to make major changes to the primary air duct 106 of the DC burner during construction and installation, thereby greatly reducing the construction difficulty and construction period.

[0048] Therefore, the combustion system 100 adapted for flexible peak regulation of tangentially-intersecting boilers according to the embodiment of the present invention has the advantages of low construction difficulty and short construction period.

[0049] In addition, since the swirl burner 2 in the related art is heavy and large in size, the combustion system 100 adapted for flexible peak regulation of a four-corner cut-circle boiler in an embodiment of the present invention needs to design the size of the swirl burner 2 to be smaller in order to place the swirl burner 2 in the primary air channel 106. Compared with the related art, it is also beneficial to save materials and construction costs.

[0050] Optionally, as shown in the figure, the DC burner further includes a secondary air channel 107. The secondary air channel 107 is provided above the primary air channel 106. The secondary air required by the secondary air channel 107 is provided by the secondary air box of the boiler.

[0051] In some embodiments, a combustion system 100 adapted for flexible peak load regulation of tangentially-intersecting boilers includes five coal mills, a first fan 5, and a pulverized coal conveying system 4. The five coal mills correspond one-to-one to five layers of DC burners. Each coal mill is connected to the primary air duct 106 of each DC burner in its corresponding DC burner layer. The first fan 5 is connected to all five coal mills so that the primary air generated by the first fan 5 blows the pulverized coal in the coal mills into the corresponding primary air duct 106.

[0052] The powder conveying system 4 includes a powder storage bin 401, a powder feeding bin 402, a powder conveying pipe 403, a discharger 405, a powder feeder 406 and a second fan 404. The powder storage bin 401 is connected to the powder feeding bin 402 through the discharger 405, the powder feeding bin 402 is connected to the powder conveying pipe 403 through the powder feeder 406, the powder conveying pipe 403 is connected to the inlet end of the air-powder pipe 202 of each swirl burner 2, and the air outlet of the second fan 404 is connected to the powder conveying pipe 403, so that the fuel in the powder feeding bin 402 is transported to the air-powder pipe 202 through the powder conveying pipe 403.

[0053] For example, Figure 1As shown, there are five coal mills, which are, from bottom to top, the first coal mill 301, the second coal mill 302, the third coal mill 303, the fourth coal mill 304 and the fifth coal mill 305. The first coal mill 301 is connected to the primary air channel 106 of each DC burner in the first layer of DC burners 101, so that the primary air generated by the first fan 5 blows the coal powder in the first coal mill 301 into the primary air channel 106 of all DC burners in the first layer of DC burners 101; the second coal mill 302 is connected to the primary air channel 106 of each DC burner in the second layer of DC burners 102, so that the primary air generated by the first fan 5 blows the coal powder in the second coal mill 302 into the primary air channel 106 of all DC burners in the second layer of DC burners 102; the third coal mill 303 is connected to the primary air channel 106 of each DC burner in the third layer of DC burners 103, so that the primary air generated by the first fan 5 The primary air blows the pulverized coal in the third coal mill 303 into the primary air channel 106 of all the DC burners in the third layer of DC burners 103; the fourth coal mill 304 is connected to the primary air channel 106 of each DC burner in the fourth layer of DC burners 104, so that the primary air generated by the first fan 5 blows the pulverized coal in the fourth coal mill 304 into the primary air channel 106 of all the DC burners in the fourth layer of DC burners 104; the fifth coal mill 305 is connected to the primary air channel 106 of each DC burner in the fifth layer of DC burners 105, so that the primary air generated by the first fan 5 blows the pulverized coal in the fifth coal mill 305 into the primary air channel 106 of all the DC burners in the fifth layer of DC burners 105.

[0054] The pulverized fuel conveying system 4 of the swirl burners 2 provides fuel for all swirl burners 2. The pulverized fuel stored in the pulverized fuel storage bin 401 is transported by a discharger 405 into the pulverized fuel supply bin 402. The pulverized fuel in the pulverized fuel supply bin 402 is then transported by a pulverized fuel feeder 406 into the pulverized fuel pipe 403. The primary air from the outlet of the second blower 404 propels the fuel in the pulverized fuel pipe 403 into the air-powder pipe 202. The pulverized fuel in the pulverized fuel storage bin 401 can be purchased high-quality steam coal, biomass powder, or high-ash, low-calorific value pulverized coal produced by the power plant's coal mills.

[0055] Therefore, the combustion system 100 adapted for flexible peak regulation of four-corner tangential boilers in an embodiment of the present invention, by setting the powder conveying system 4 of the swirl burner 2 into an independent powder conveying system 4 to input different combustion media into the swirl burner 2, makes the range of use of the fuel required by the swirl burner 2 of the combustion system 100 adapted for flexible peak regulation of four-corner tangential boilers in an embodiment of the present invention larger.

[0056] In some embodiments, the swirl burner 2 includes an air guide tube 201, an air powder tube 202, a cyclone 203, and a reflux cap 204. The outlet end of the air guide tube 201 is placed in the primary air channel 106. The air powder tube 202 and the air guide tube 201 are spaced apart in the radial direction of the air powder tube 202, and the outlet end of the air powder tube 202 is placed in the air guide tube 201. The cyclone 203 is provided on the air powder tube 202. The outlet end of the cyclone 203 is connected to the air guide tube 201. The boiler fan is connected to the air duct. The inlet end of the cyclone 203 is connected to the secondary air box of the boiler through the air duct. The cyclone 203 is used to rotate the air at 300°C to 400°C in the air duct and input it into the air guide tube 201. A secondary air valve is provided between the cyclone 203 and the secondary air box. The secondary air valve is used to adjust the flow rate of secondary air entering the cyclone 203. The reflux cap 204 is disposed in the air guide tube 201 and is located at the outlet end of the air-powder tube 202 . The reflux cap 204 and the air-powder tube 202 are spaced apart from each other in the axial direction of the air-powder tube 202 .

[0057] For example, Figure 1 and Figure 2 As shown, the primary air generated by the first fan 5 blows the pulverized coal into the primary air duct 106 of the DC burner. The primary air generated by the second fan 404 blows the fuel in the powder conveying pipe 403 into the air-powder pipe 202. The pulverized coal airflow passes through the return channel formed by the air-powder pipe 202 and the return cap 204, and then flows back into the air guide 201. The 300°C to 400°C air in the air duct passes through the cyclone 203 and enters the air guide 201, turning the airflow into a rotating airflow with a tangential velocity. The rotating airflow passes through the air guide 201, mixes with the pulverized coal airflow entering the air guide 201, and then burns. The airflow then enters the primary air duct 106 of the DC burner, preheating and igniting the pulverized coal in the primary air duct 106.

[0058] Therefore, the combustion system 100 adapted for flexible peak regulation of four-corner tangential boilers in the embodiment of the present invention utilizes the advantages of the swirl burner 2 having a strong ability to draw in high-temperature flue gas and a better self-stabilizing combustion ability to solve the problem of stable combustion of the direct current burner at low load, thereby making the combustion system 100 adapted for flexible peak regulation of four-corner tangential boilers in the embodiment of the present invention have high working reliability.

[0059] In some embodiments, the ratio of the diameter of the outlet end of the air guide tube 201 to the height of the primary air channel 106 is 0.3 to 0.8.

[0060] For example, the ratio of the diameter of the outlet end of the air guide 201 to the height of the primary air duct 106 is 0.5. By properly setting the ratio of the diameter of the outlet end of the air guide 201 to the height of the primary air duct 106, it is possible to prevent the combustion flame ejected from the swirl burner 2 from fully contacting the inner wall of the primary air duct 106 in the DC burner, thereby preventing the DC burner primary air duct 106 from overheating and deforming. This is beneficial for improving the operating reliability of the combustion system 100 adapted for flexible peak load regulation of tangentially-intersecting boilers according to the embodiment of the present invention.

[0061] Optionally, the air guide tube 201 is a conical tube, and the diameter of the air guide tube 201 gradually decreases from the outlet end of the air guide tube 201 to the inlet end of the air guide tube 201 .

[0062] For example, Figure 2 As shown, by setting the air guide tube 201 as a conical tube, it is beneficial to the diffusion of the flame sprayed by the swirl burner 2 and improves the stable combustion effect of the swirl burner 2.

[0063] In some embodiments, the ratio of the maximum diameter of the flame that can be ejected by the swirl burner 2 to the equivalent diameter of the primary air channel 106 is 0.5 to 1.0.

[0064] For example, the ratio of the maximum diameter of the flame that can be ejected by the swirl burner 2 to the equivalent diameter of the primary air duct 106 is 0.8. By properly setting the ratio of the maximum diameter of the flame that can be ejected by the swirl burner 2 to the equivalent diameter of the primary air duct 106, it is possible to prevent the swirl flame ejected by the swirl burner 2 from fully contacting the inner wall of the primary air duct 106, thereby preventing overheating and deformation of the primary air duct 106 of the DC burner. This further improves the operational reliability of the combustion system 100 adapted for flexible peak shaving of tangentially shaped boilers according to the embodiment of the present invention during deep peak shaving.

[0065] In some embodiments, the speed of the flame that can be ejected by the swirl burner 2 is greater than 30 m / s.

[0066] In some embodiments, the ratio of the power of a single swirl burner 2 to the power of a single direct current burner is 0.1 to 0.5.

[0067] For example, the ratio of the power of a single swirl burner 2 to the power of a single DC burner is 0.3. The ratio of the power of a single swirl burner 2 to the power of a single DC burner can be reasonably set according to actual needs to match the power of the swirl burner 2 with the power of the DC burner, thereby improving the operating reliability of the combustion system 100 adapted for flexible peak load regulation of tangentially-intersecting boilers according to the embodiment of the present invention.

[0068] The combustion method adapted for flexible peak regulation of a tangentially-interconnected boiler according to an embodiment of the present invention is based on the combustion system 100 adapted for flexible peak regulation of a tangentially-interconnected boiler described in the above embodiment, and includes:

[0069] When the boiler needs to work at rated load, the swirl burner 2 is in a shutdown state, and the DC burners in each layer are in a running state;

[0070] When the boiler needs deep peak regulation to reduce the operating load, first start the swirl burner 2 in at least one layer of the stable combustion DC burner layer, and then shut down the DC burner layers other than at least one of the stable combustion DC burner layers where the swirl burner 2 is started, that is, shut down the coal mills corresponding to the DC burner layers to be shut down;

[0071] When the deep peak regulation of the boiler is completed and the boiler operating load needs to be restored, the DC burners in the DC burner layer that need to be operated are determined and started in order from bottom to top according to the boiler operating load requirements, that is, the coal mill corresponding to the started DC burner layer. When the boiler operating load reaches more than 50% of the rated load, all swirl burners 2 can be shut down or continue to operate.

[0072] For example, Figure 1 As shown, the first layer of DC burners 101 is a stable combustion DC burner, and a swirl burner 2 is provided in the primary air channel 106 of the DC burner in the first layer of DC burners 101.

[0073] When the boiler needs to work at rated load, all swirl burners 2 are shut down and the DC burners in the five-layer DC burners are started;

[0074] When the boiler needs deep peak regulation to reduce the operating load to 40% of the rated load, the swirl burner 2 in the first layer of DC burners 101 is started. Then, after all the swirl burners 2 in the first layer of DC burners 101 are started, the DC burners in the fifth layer, the fourth layer, and the third layer are shut down. The swirl burner 2 in the first layer of DC burners 101 uses its own strong ability to entrain high-temperature flue gas and good self-stabilizing combustion ability to stabilize the DC burners in the first layer of DC burners 101, preventing the DC burners from igniting unstably under low load.

[0075] When the deep peak regulation of the boiler is completed and the boiler operating load needs to return to 60% of the rated load, the DC burners in the third layer of DC burners 103 that were previously shut down are started, and the fourth layer of DC burners 104 and the fifth layer of DC burners 105 remain in a shut-down state. When the boiler operating load reaches 50% or more of the rated load, all swirl burners 2 can be shut down or continue to operate.

[0076] When the deep peak regulation of the boiler is completed and the boiler operating load needs to return to 80% of the rated load, the DC burners in the third layer DC burner 103 and the fourth layer DC burner 104 that were previously shut down are started in sequence from bottom to top, and the fifth layer DC burner 105 remains shut down. When the boiler operating load reaches more than 50% of the rated load, all swirl burners 2 can be shut down or continue to operate.

[0077] When the deep peak regulation of the boiler is completed and the boiler operating load needs to return to 100% of the rated load, the DC burners in the third layer DC burner 103, the fourth layer DC burner 104 and the fifth layer DC burner 105 that were previously shut down are started in sequence from bottom to top. When the boiler operating load reaches more than 50% of the rated load, all swirl burners 2 can be shut down or continue to operate.

[0078] The combustion method adapted for flexible peak regulation of tangentially-circled boilers according to the embodiment of the present invention has advantages such as high reliability.

[0079] Optionally, when shutting down the swirl burner 2, the frequency of the feeder of the swirl burner 2 is gradually reduced, and the secondary air valve of the swirl burner is adjusted at the same time. When the feeder frequency is reduced to 5Hz, the feeder can be directly shut down, and the second fan continues to run. The hot primary air in the air-powder tube 202 is blown for 10 to 15 minutes and then shut down, and the opening of the secondary air valve is kept at 10% to 20%.

[0080] In some embodiments, the combustion method adapted for flexible peak load regulation of a tangentially-circular boiler according to an embodiment of the present invention includes:

[0081] When the boiler is performing deep peak regulation and the four swirl burners 2 in the stable combustion DC burner layer are ignited and started, first, the second fan 404 is started, and the powder feeder 406 is kept in a stopped state. The primary air generated by the second fan 404 blows the air powder pipe 202 of one of the swirl burners 2 in the stable combustion DC burner layer for 1 to 3 minutes, and after the primary air pressure is stabilized, the second fan 404 is stopped; secondly, the secondary air valve of the swirl burner 2 is started, with an opening of 5% to 10%, and the second fan 404 is started. After stabilization for 30 to 60 seconds, the ignition oil gun of the swirl burner 2 is started to observe the stability of the fuel flame; then, the powder feeder 406 is started, so that the powder feeder bin 40 2 is transported to the swirl burner 2 under the action of the second fan 404 and ignited by the fuel flame, and the secondary air valve opening of the swirl burner 2 and the frequency of the powder feeder 406 are increased. After the frequency of the powder feeder 406 reaches the rated power, it will no longer increase. At the same time, the secondary air valve will no longer increase after it is increased to the preset opening. The amount of swirl secondary air added is designed according to the excess air coefficient ≯1, so as to ensure that the flame is rich in reducing atmosphere such as CO, H2, CH4, etc., and reduce NOx generation; finally, according to the same method, the remaining three swirl burners 2 are ignited in turn, and after all four swirl burners 2 are ignited, the ignition oil guns of the four swirl burners 2 are shut down to stop the oil combustion.

[0082] In some embodiments, a combustion method adapted for flexible peak shaving of a tangentially-interconnected boiler according to an embodiment of the present invention is based on the combustion system 100 adapted for flexible peak shaving of a tangentially-interconnected boiler according to any of the above embodiments, including:

[0083] When the fuel with a calorific value of 2000kcal / kg to 4000kcal / kg is introduced into the air-powder tube 202, the swirl intensity of the cyclone 203 is 0.6 to 1.0;

[0084] When the fuel with a calorific value of 3500kcal / kg to 5000kcal / kg is introduced into the air-powder tube 202, the swirl intensity of the cyclone 203 is 0.6 to 3.0;

[0085] When fuel with a calorific value greater than or equal to 5000 kcal / kg is introduced into the air-powder tube 202 , the swirl intensity of the swirl burner 2 is less than or equal to 0.6.

[0086] Therefore, the swirl burner 2 can select different swirl intensities according to fuels with different calorific values ​​to meet the use requirements of the swirl burner 2, so that the selection range of fuel required by the swirl burner 22 is larger.

[0087] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0088] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0089] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0090] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0091] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0092] Although the above embodiments have been shown and described, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those skilled in the art are all within the scope of protection of the present invention.

Claims

1. A combustion system suitable for flexible peak regulation of tangentially fired boilers, characterized in that: include: furnace; Five layers of DC burners, the five layers of DC burners are spaced apart in the vertical direction of the furnace, and the five layers of DC burners are, from bottom to top, a first layer of DC burners, a second layer of DC burners, a third layer of DC burners, a fourth layer of DC burners, and a fifth layer of DC burners. Each layer of DC burners includes four DC burners respectively located at the four corners of the furnace, and the DC burners have a primary air channel; and Swirl burners, the number of which is four or more, at least one layer of DC burners being a stable combustion DC burner layer, and each of the four DC burners in the stable combustion DC burner layer is provided with a swirl burner in the primary air channel; The swirl burner comprises: An air guide tube, the outlet end of which is placed in the primary air channel; An air powder tube, wherein the air powder tube and the air guide tube are spaced apart in the radial direction of the air powder tube, and the outlet end of the air powder tube is placed in the air guide tube; A cyclone, the cyclone being provided on the air-powder tube, the outlet end of the cyclone being in communication with the air guide duct, the boiler having an air duct and a secondary air box, the inlet end of the cyclone being in communication with the secondary air box of the boiler via the air duct, the cyclone being used to rotate air at a temperature of 300°C to 400°C in the air duct and input it into the air guide duct, a secondary air valve being provided between the cyclone and the secondary air box, the secondary air valve being used to regulate the flow rate of secondary air entering the cyclone; and A reflux cap is provided in the air guide tube and is located at the outlet end of the air-powder tube. The reflux cap and the air-powder tube are spaced apart in the axial direction of the air-powder tube.

2. The combustion system adapted for flexible peak load regulation of tangentially-intersecting boilers according to claim 1 is characterized in that: The ratio of the diameter of the outlet end of the air guide tube to the height of the primary air channel is 0.3 to 0.

8.

3. The combustion system adapted for flexible peak load regulation of tangentially-intersecting boilers according to claim 1 is characterized in that: The air guide tube is a conical tube, and the diameter of the air guide tube gradually decreases along the direction from the outlet end of the air guide tube to the inlet end of the air guide tube.

4. The combustion system adapted for flexible peak load regulation of tangentially-intersecting boilers according to claim 1 is characterized in that: The ratio of the maximum diameter of the flame that can be ejected by the swirl burner to the equivalent diameter of the primary air channel is 0.5 to 1.0; and / or The speed of the flame that can be ejected by the swirl burner is greater than 30 m / s.

5. The combustion system adapted for flexible peak regulation of tangentially-intersecting boilers according to claim 1 is characterized in that: The ratio of the power of a single swirl burner to the power of a single direct current burner is 0.1 to 0.

5.

6. The combustion system suitable for flexible peak regulation of tangentially-intersecting boilers according to any one of claims 1 to 5, characterized in that: include: Five coal mills and a first fan, the five coal mills corresponding one-to-one to the five layers of DC burners, each coal mill being connected to the primary air passages of the four DC burners in the corresponding DC burner layer, and the first fan being connected to all five coal mills so that the primary air delivered by the first fan blows the pulverized coal in the coal mills into the corresponding primary air passages; and A powder conveying system, the powder conveying system includes a powder storage bin, a powder feeding bin, a powder conveying pipe, a discharger, a powder feeder and a second fan. The powder storage bin is connected to the powder feeding bin through the discharger, the powder feeding bin is connected to the powder conveying pipe through the powder feeder, the powder conveying pipe is connected to the inlet end of the air-powder pipe of each swirl burner, and the air outlet of the second fan is connected to the powder conveying pipe, so that the fuel in the powder feeding bin is transported to the air-powder pipe through the powder conveying pipe.

7. A combustion method suitable for flexible peak regulation of tangentially fired boilers, characterized in that: The method is based on the combustion system adapted for flexible peak regulation of tangentially-intersecting boilers as described in claim 6, comprising: When the boiler needs to operate under rated load, the swirl burner is in a shutdown state, and the direct current burners in each layer are in an operating state; When the boiler needs deep peak regulation to reduce the operating load, the swirl burners in at least one layer of the stable combustion direct current burner layer are first started, and then, in order from top to bottom, the direct current burner layers other than at least a part of the stable combustion direct current burner layer in which the swirl burners are started are shut down, that is, the coal mills corresponding to the direct current burner layers to be shut down are shut down; When the deep peak regulation of the boiler is completed and the boiler operating load needs to be restored, the DC burners in the DC burner layer that need to be operated are determined and started in order from bottom to top according to the boiler operating load requirements, that is, the coal mill corresponding to the DC burner layer is started. When the boiler operating load reaches more than 50% of the rated load, all the swirl burners are shut down.

8. The combustion method adapted for flexible peak load regulation of tangentially-intersecting boilers according to claim 7 is characterized in that: include: When the boiler performs deep peak regulation and the four swirl burners in the stable combustion direct current burner layer are ignited and started, first, the second blower is started, and the powder feeder is kept in a stopped state. The primary air generated by the second blower blows the air-powder pipe of one of the swirl burners in the stable combustion direct current burner layer for 1 minute to 3 minutes. After the primary air pressure stabilizes, the second blower is stopped; Secondly, start the secondary air valve of the swirl burner with an opening of 5% to 10%, start the second fan, and after stabilizing for 30s to 60s, start the ignition oil gun of the swirl burner and observe the stability of the fuel flame; Then, the powder feeder is started, so that the fuel in the powder feeding bin is transported to the swirl burner by the action of the second fan and ignited by the fuel flame. The opening of the secondary air valve of the swirl burner and the frequency of the powder feeder are increased. After the powder feeder frequency reaches the rated power, it will not be increased. At the same time, after the secondary air valve is increased to a preset opening, it will not be increased. The amount of swirl secondary air is designed according to the excess air coefficient ≯ 1. Finally, the remaining three swirl burners are ignited in sequence according to the same method. After all four swirl burners are ignited, the ignition oil guns of the four swirl burners are stopped to stop the accompanying oil combustion.

9. A combustion method suitable for flexible peak regulation of tangentially fired boilers, characterized in that: The method is based on a combustion system suitable for flexible peak regulation of a tangentially-circular boiler according to any one of claims 1 to 6, comprising: When the fuel with a calorific value of 2000kcal / kg to 4000kcal / kg is introduced into the air-powder tube, the swirl intensity of the cyclone is 0.6 to 1.0; When the fuel with a calorific value of 3500kcal / kg to 5000kcal / kg is introduced into the air-powder pipe, the swirl intensity of the cyclone is 0.6 to 3.0; When fuel with a calorific value greater than or equal to 5000 kcal / kg is introduced into the air-powder tube, the swirl intensity of the swirl burner is less than or equal to 0.6.

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