Gas-powder dual-fuel burner

Abstract

The present invention discloses a gas-powder dual-fuel burner. The gas-powder dual-fuel burner includes a burner body, and the burner body has a primary air passage, a flame stabilization chamber, a gas passage, gas injection holes, a secondary air passage, a pre-combustion chamber, and a tertiary air passage. There is an included angle between the gas injection holes and the secondary air passage. The pre-combustion chamber is located downstream of the flame stabilization chamber. The primary air can form a primary air recirculation zone at the outlet of the flame stabilization chamber, and the secondary air can form a secondary air recirculation zone in the pre-combustion chamber. The secondary air recirculation zone intersects with the primary air recirculation zone. Under the action of the primary air recirculation zone and the secondary air recirculation zone, the fuel can achieve rapid and stable ignition, enabling more recycled flue gas to be incorporated into the secondary air and the tertiary air to reduce the oxygen content and lower the generation of nitrogen oxides during the combustion process. The gas is tangentially injected into the secondary air passage, so that the gas and the secondary air can be quickly and evenly mixed.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler equipment, and particularly to a gas-powder dual-fuel burner. Background Art

[0002] Conventional fuels for boilers are usually divided into powder fuels, gas fuels, and liquid fuels. In related technologies, most dual-fuel burners are simple superpositions of original pulverized coal burners and gas nozzles, and they have deficiencies in simultaneously considering the stable combustion of pulverized coal, the uniform mixing of natural gas and combustion-supporting air, and low nitrogen emissions. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related technologies to some extent.

[0004] To this end, an embodiment of the present invention provides a gas-powder dual-fuel burner, which can achieve the separate or blended combustion of pulverized coal fuel and gas fuel.

[0005] The gas-powder dual-fuel burner according to the embodiment of the present invention includes a burner body, the burner body having a primary air passage, a stable combustion chamber, a gas passage, gas injection holes, a secondary air passage, a pre-combustion chamber, and a tertiary air passage. The primary air passage, the gas passage, and the secondary air passage are sequentially and spaced apart from inside to outside along the radial direction of the primary air passage. The stable combustion chamber is located downstream of the primary air passage and is connected to the primary air passage. The cross-sectional area of the stable combustion chamber gradually increases in the upstream to downstream direction, and the primary air can form a primary air recirculation zone at the outlet of the stable combustion chamber. The gas passage is connected to the secondary air passage through the gas injection holes, and there is an included angle between the extending direction of the gas injection holes and the extending direction of the secondary air passage. The pre-combustion chamber is located downstream of the secondary air passage and the stable combustion chamber and is connected to the secondary air passage and the stable combustion chamber. The cross-sectional area of the pre-combustion chamber gradually increases in the upstream to downstream direction, and the secondary air can form a secondary air recirculation zone in the pre-combustion chamber. The secondary air recirculation zone is located downstream of the primary air recirculation zone and intersects with the primary air recirculation zone. The tertiary air passage is located outside the pre-combustion chamber, and the outlet of the tertiary air passage extends towards the direction close to the central axis of the pre-combustion chamber.

[0006] In the pulverized coal and gas dual-fuel burner according to the embodiment of the present invention, a primary air recirculation zone is formed at the outlet of the stable combustion chamber, and a secondary air recirculation zone is formed in the pre-combustion chamber. The fuel passes through the primary air recirculation zone and the secondary air recirculation zone and is heated twice in the pre-combustion chamber, thereby realizing the rapid ignition and stable ignition of the fuel, improving the ignition and stable combustion performance of the burner, enabling the fuel to be extended to fuels with low volatile content and low calorific value, so that more recycled flue gas can be incorporated into the secondary air and the tertiary air to reduce the oxygen content, and further reducing the generation of nitrogen oxides during the combustion process. Moreover, the gas is tangentially injected into the secondary air passage through the gas injection holes, thereby quickly and uniformly mixing the gas with the secondary air.

[0007] Thus, the pulverized coal and gas dual-fuel burner according to the embodiment of the present invention solves the problems of insufficient fuel stable combustion, mixing of gas and combustion-supporting air (secondary air), and low nitrogen emission.

[0008] In some embodiments, the burner body includes an igniter, a primary air seal ring, a primary air cylinder, and a primary air inlet pipe. The primary air seal ring is sleeved on the igniter. The primary air cylinder includes a connected primary air straight section and a primary air diffusion section. The primary air diffusion section is located downstream of the primary air straight section. The primary air straight section is sleeved on at least part of the outside of the igniter. The igniter and the primary air straight section are spaced apart in the inner and outer directions. The primary air seal ring is detachably connected to the primary air straight section. The igniter, the primary air straight section, and the primary air seal ring define the primary air passage. The inner cavity of the primary air diffusion section is the stable combustion chamber. The cross-sectional area of the primary air diffusion section gradually increases in the upstream to downstream direction. The primary air straight section is provided with primary air inlet holes communicating with the primary air passage. The primary air inlet pipe is connected to the primary air straight section, and the inner cavity of the primary air inlet pipe is connected to the primary air passage through the primary air inlet holes.

[0009] In some embodiments, a first axial impeller assembly is provided in the primary air passage. The first axial impeller assembly is used to make the primary air form a rotating air flow with tangential velocity after passing through the first axial impeller assembly. The first axial impeller assembly includes a first blade ring and a plurality of first axial blades. The first blade ring is sleeved on the igniter. The plurality of first axial blades are circumferentially spaced on the first blade ring. There is a gap of 2-5 mm between the blade tips of the first axial blades and the inner wall of the primary air straight section.

[0010] In some embodiments, the burner body further includes a gas cylinder, a first gas sealing ring, a second gas sealing ring, and a gas inlet pipe. The gas cylinder is sleeved outside the primary air cylinder. The primary air cylinder and the gas cylinder are spaced apart in the inner and outer directions. The gas cylinder includes a connected gas straight section and a gas diffusion section. The gas diffusion section is located downstream of the gas straight section. The cross-sectional area of the gas diffusion section gradually increases in the upstream to downstream direction. The inner end of the first gas sealing ring is connected to the primary air cylinder, and the outer end of the first gas sealing ring is connected to the gas straight section. The inner end of the second gas sealing ring is connected to the primary air cylinder, and the outer end of the second gas sealing ring is connected to the gas diffusion section. The primary air cylinder, the gas straight section, the gas diffusion section, the first gas sealing ring, and the second gas sealing ring define the gas passage. The gas injection holes are provided on the gas diffusion section. The gas straight section is provided with a gas inlet hole and a relief hole communicating with the gas passage. The gas inlet pipe is connected to the gas straight section, and the inner chamber of the gas inlet pipe is communicated with the gas passage through the gas inlet hole. The primary air inlet pipe penetrates through the relief hole.

[0011] In some embodiments, a first fastener is further included. The primary air sealing ring is provided with a first mounting hole, and the first gas sealing ring is provided with a second mounting hole. The first fastener is sequentially engaged with the first mounting hole and the second mounting hole.

[0012] In some embodiments, the burner body further includes a secondary air cylinder, a secondary air sealing ring, and a secondary air inlet pipe. The secondary air cylinder includes a connected secondary air straight section and a secondary air diffusion section. The secondary air diffusion section is located downstream of the secondary air straight section. The secondary air straight section is sleeved outside at least a part of the gas cylinder. The gas cylinder and the secondary air straight section are spaced apart in the inner and outer directions. The inner end of the secondary air sealing ring is connected to the gas cylinder, and the outer end of the secondary air sealing ring is connected to the secondary air straight section. The gas cylinder, the secondary air straight section, and the secondary air sealing ring define the secondary air passage. The inner chamber of the secondary air diffusion section is the pre-combustion chamber. The cross-sectional area of the secondary air diffusion section gradually increases in the upstream to downstream direction. The secondary air straight section is provided with a secondary air inlet hole communicating with the secondary air passage. The secondary air inlet pipe is connected to the secondary air straight section, and the inner chamber of the secondary air inlet pipe is communicated with the secondary air passage through the secondary air inlet hole. The included angle between the extending direction of the gas injection holes and the extending direction of the secondary air passage is 45° - 135°.

[0013] In some embodiments, the secondary air seal ring includes a first seal ring portion and a second seal ring portion that are detachably connected. The inner end of the first seal ring portion is connected to the gas straight section, and the outer end of the second seal ring portion is connected to the secondary air straight section. The pulverized coal and gas dual-fuel burner further includes a second fastener. The first seal ring portion is provided with a third mounting hole, and the second seal ring portion is provided with a fourth mounting hole. The second fastener cooperates with the third mounting hole and the fourth mounting hole in sequence.

[0014] In some embodiments, the burner body further includes a tertiary air cylinder, a tertiary air seal ring, and a tertiary air inlet pipe. The tertiary air cylinder sleeves at least part of the secondary air cylinder, and the secondary air cylinder and the tertiary air cylinder are spaced apart in the inner and outer directions. The tertiary air cylinder includes a connected tertiary air straight section and a tertiary air contraction section. The tertiary air contraction section is located downstream of the tertiary air straight section, and the cross-sectional area of the tertiary air contraction section gradually decreases in the upstream to downstream direction. The inner end of the tertiary air seal ring is connected to the secondary air cylinder, and the outer end of the tertiary air seal ring is connected to the tertiary air straight section. The secondary air cylinder, the tertiary air seal ring, and the tertiary air cylinder define the tertiary air passage. The tertiary air straight section is provided with a tertiary air inlet hole communicating with the tertiary air passage. The tertiary air inlet pipe is connected to the tertiary air straight section, and the internal cavity of the tertiary air inlet pipe is connected to the tertiary air passage through the tertiary air inlet hole.

[0015] In some embodiments, the secondary air cylinder further includes a secondary air contraction section. The secondary air contraction section is located downstream of the secondary air diffusion section and is connected to the secondary air diffusion section. The cross-sectional area of the secondary air contraction section gradually decreases in the upstream to downstream direction, and the two ends of the secondary air contraction section and the tertiary air contraction section are flush.

[0016] In some embodiments, a second axial impeller assembly is provided in the tertiary air passage. The second axial impeller assembly is used to make the tertiary air form a rotating air flow with a tangential velocity after passing through the second axial impeller assembly. The second axial impeller assembly includes a second blade ring and a plurality of second axial blades. The second blade ring sleeves on the secondary air contraction section, and the plurality of second axial blades are circumferentially spaced on the second blade ring. There is a gap of 3-10 mm between the blade tips of the second axial blades and the inner wall of the tertiary air contraction section. Description of the Drawings

[0017] Figure 1 is the first schematic structural diagram of the pulverized coal and gas dual-fuel burner according to the embodiment of the present invention.

[0018] Figure 2 is the second schematic structural diagram of the pulverized coal and gas dual-fuel burner according to the embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of the flow field of the gas-powder dual-fuel burner according to an embodiment of the present invention.

[0020] Figure 4 It is a schematic diagram of the annular flame at the outlet of the gas-powder dual-fuel burner according to an embodiment of the present invention.

[0021] Figure 5

[0022] It is a schematic diagram of the flame lengths of the secondary air and the tertiary air in different proportions of the gas-powder dual-fuel burner according to an embodiment of the present invention. Reference numerals:

[0023] Primary air recirculation zone 100, secondary air recirculation zone 200,

[0024] Burner body 1,

[0025] Igniter 11, primary air seal ring 12, primary air cylinder 13, primary air straight section 131, primary air passage 1311, primary air diffusion section 132, stable combustion chamber 1321, primary air input pipe 14, first axial impeller assembly 15,

[0026] Gas cylinder 16, gas straight section 161, gas passage 1611, gas diffusion section 162, gas injection holes 1621, first gas seal ring 17, second gas seal ring 18, gas input pipe 19, first fastener 20,

[0027] Secondary air cylinder 21, secondary air straight section 211, secondary air passage 2111, secondary air diffusion section 212, pre-combustion chamber 2121, secondary air contraction section 213, secondary air seal ring 22, first seal ring part 221, second seal ring part 222, secondary air input pipe 23, second fastener 24,

[0028] Tertiary air cylinder 25, tertiary air straight section 251, tertiary air passage 2511, tertiary air contraction section 252, tertiary air seal ring 26, tertiary air input pipe 27, second axial impeller assembly 28. Detailed implementation manners

[0029] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0030] The gas-powder dual-fuel burner according to an embodiment of the present invention will be described below with reference to the drawings.

[0031] As Figures 1 to 3As shown in the figure, the air-powder dual-fuel burner of the embodiment of the present invention includes a burner body 1, and the burner body 1 has a primary air passage 1311, a stable combustion chamber 1321, a gas passage 1611, a gas injection hole 1621, a secondary air passage 2111, a pre-combustion chamber 2121, and a tertiary air passage 2511. Among them, primary air, or primary air and pulverized coal, can be transported to the burner body 1 through the primary air passage 1311, that is, the pulverized coal fuel is transported by the primary air. Gas can be transported to the burner body 1 through the gas passage 1611, secondary air can be transported to the burner body 1 through the secondary air passage 2111, and tertiary air can be transported to the burner body 1 through the tertiary air passage 2511. Moreover, the primary air passage 1311, the gas passage 1611, and the secondary air passage 2111 are sequentially and spaced apart from inside to outside along the radial direction of the primary air passage 1311.

[0032] The stable combustion chamber 1321 is located downstream of the primary air passage 1311 and is connected to the primary air passage 1311. The cross-sectional area of the stable combustion chamber 1321 gradually increases in the upstream to downstream direction (such as Figure 1 or Figure 2 the front-back direction in the figure), and the primary air can form a primary air recirculation zone 100 at the outlet of the stable combustion chamber 1321. It can be understood that the primary air and the pulverized coal enter the stable combustion chamber 1321 through the primary air passage 1311, and under the action of the wall surfaces of the primary air passage 1311 and the stable combustion chamber 1321, a primary air recirculation zone 100 is formed at the outlet of the stable combustion chamber 1321.

[0033] The gas passage 1611 is connected to the secondary air passage 2111 through the gas injection hole 1621, and there is an included angle between the extending direction of the gas injection hole 1621 and the extending direction of the secondary air passage 2111. It can be understood that the gas is injected into the secondary air passage 2111 through the gas passage 1611 and the gas injection hole 1621 to mix the gas with the secondary air. Moreover, the gas injection hole 1621 faces the secondary air passage 2111, and there is an included angle between the extending direction of the gas injection hole 1621 and the extending direction of the secondary air passage 2111, so that the gas is tangentially injected into the flowing secondary air, thereby quickly and evenly mixing the gas with the secondary air.

[0034] The pre - combustion chamber 2121 is located downstream of the secondary air passage 2111 and the stable combustion chamber 1321 and is in communication with the secondary air passage 2111 and the stable combustion chamber 1321. The cross - sectional area of the pre - combustion chamber 2121 gradually increases in the upstream - to - downstream direction. The secondary air can form a secondary air recirculation zone 200 in the pre - combustion chamber 2121. The secondary air recirculation zone 200 is located downstream of the primary air recirculation zone 100 and intersects with the primary air recirculation zone 100. It can be understood that both the secondary air passage 2111 and the stable combustion chamber 1321 are in communication with the pre - combustion chamber 2121. The primary air mixed with pulverized coal and the secondary air mixed with gas enter the pre - combustion chamber 2121 together. Under the action of the wall surfaces of the secondary air passage 2111 and the pre - combustion chamber 2121, the mixed secondary air and gas form a secondary air recirculation zone 200 in the pre - combustion chamber 2121. The secondary air recirculation zone 200 intersects with the primary air recirculation zone 100, thereby enabling the gas and pulverized coal to mix with each other and undergo preliminary combustion in the pre - combustion chamber 2121.

[0035] Thus, under the superposition of the primary air recirculation zone 100 and the secondary air recirculation zone 200, the gas first enters the secondary air recirculation zone 200 and then enters the primary air recirculation zone 100. The pulverized coal that first enters the primary air recirculation zone 100 also enters the downstream secondary air recirculation zone 200, enabling both the gas and the pulverized fuel to be heated twice, thereby achieving the effects of rapid ignition and stable ignition of the fuel in the gas - powder dual - fuel burner of the embodiment of the present invention.

[0036] In addition, those skilled in the art can understand that the burner is in communication with the furnace of the boiler. For boilers with a capacity of 14MW - 80MW, 1 - 2 gas - powder dual - fuel burners of the embodiment of the present invention are installed. For boilers with a capacity greater than 80MW, more than 3 gas - powder dual - fuel burners of the embodiment of the present invention are installed. The gas - powder dual - fuel burner of the embodiment of the present invention can be used in industrial boilers such as steam boilers and hot - water boilers, and can also be used in power station boilers such as thermal power plants. Moreover, the volume of the pre - combustion chamber 2121 is relatively small compared to the volume of the furnace of the boiler, which also makes the volumetric heat load of the pre - combustion chamber 2121 large and relatively easy to maintain in a high - temperature environment.

[0037] The tertiary air passage 2511 is located outside the pre - combustion chamber 2121, and the outlet of the tertiary air passage 2511 extends in the direction towards the central axis of the pre - combustion chamber 2121. It can be understood that since the main function of the secondary air is to accelerate the mixing with the gas and supplement the air required in the initial ignition stage, and the tertiary air is to supplement the air required in the burnout stage, the oxygen content of the secondary air is not less than that of the tertiary air. Moreover, the gas - powder dual - fuel burner of the embodiment of the present invention has good ignition and stable combustion performance, enabling the fuel to be extended to low - volatile and low - calorific - value fuels. Thus, more recycled flue gas can be mixed into the secondary air and the tertiary air to reduce the oxygen content, thereby reducing the generation of nitrogen oxides during the combustion process.

[0038] Optionally, the cross-sectional shapes of the primary air passage 1311, the gas passage 1611, the secondary air passage 2111, and the tertiary air passage 2511 are all annular, and both the stable combustion cavity 1321 and the pre-combustion cavity 2121 are frustum-shaped with a smaller upstream and a larger downstream. As Figure 1 and Figure 2 shown, the gas passage 1611 surrounds the outer peripheral sides of the primary air passage 1311 and the stable combustion cavity 1321, the secondary air passage 2111 surrounds the outer peripheral side of the gas passage 1611, and the tertiary air passage 2511 surrounds the outer peripheral side of the pre-combustion cavity 2121. The rear end of the primary air passage 1311 is connected to the front end of the stable combustion cavity 1321, and the rear ends of both the stable combustion cavity 1321 and the secondary air passage 2111 are connected to the front end of the pre-combustion cavity 2121. The gas injection holes 1621 are located between the gas passage 1611 and the secondary air passage 2111 to connect the gas passage 1611 and the secondary air passage 2111. The rear ends of both the pre-combustion cavity 2121 and the tertiary air passage 2511 are connected to the furnace of the boiler (not shown in the figure).

[0039] For example, when pulverized coal fuel and gas fuel are mixed and burned, primary air and pulverized coal are simultaneously introduced into the primary air passage 1311, gas is introduced into the gas passage 1611, secondary air is introduced into the secondary air passage 2111, and tertiary air is introduced into the tertiary air passage 2511. When only pulverized coal fuel is burned, primary air and pulverized coal are simultaneously introduced into the primary air passage 1311, secondary air is introduced into the secondary air passage 2111, and tertiary air is introduced into the tertiary air passage 2511. When only gas fuel is burned, primary air is introduced into the primary air passage 1311, gas is introduced into the gas passage 1611, secondary air is introduced into the secondary air passage 2111, and tertiary air is introduced into the tertiary air passage 2511.

[0040] Thus, in the gas-pulverized coal dual-fuel burner according to the embodiment of the present invention, a primary air recirculation zone 100 is formed at the outlet of the stable combustion cavity 1321 for the primary air, a secondary air recirculation zone 200 is formed in the pre-combustion cavity 2121 for the secondary air, and the fuel passes through the primary air recirculation zone 100 and the secondary air recirculation zone 200 and is heated twice in the pre-combustion cavity 2121, thereby realizing the rapid ignition and stable ignition of the fuel, improving the ignition and stable combustion performance of the burner, enabling the fuel to be extended to low-volatile and low-calorific-value fuels, so that more recycled flue gas can be incorporated into the secondary air and the tertiary air to reduce the oxygen content, and further reducing the generation of nitrogen oxides during the combustion process. Moreover, the gas is tangentially injected into the secondary air passage 2111 through the gas injection holes 1621, thereby quickly and evenly mixing the gas with the secondary air.

[0041] In some embodiments, as Figure 1 and Figure 2As shown, the burner body 1 includes an igniter 11, a primary air seal ring 12, a primary air cylinder 13, and a primary air inlet pipe 14. The primary air seal ring 12 is sleeved on the igniter 11. The primary air cylinder 13 includes a connected primary air straight section 131 and a primary air diffuser section 132. The primary air diffuser section 132 is located downstream of the primary air straight section 131. The primary air straight section 131 is sleeved on at least part of the outside of the igniter 11. The igniter 11 and the primary air straight section 131 are spaced apart in the inner and outer directions. The primary air seal ring 12 is detachably connected to the primary air straight section 131. The igniter 11, the primary air straight section 131, and the primary air seal ring 12 define a primary air passage 1311. The inner cavity of the primary air diffuser section 132 is a stable combustion cavity 1321. The cross-sectional area of the primary air diffuser section 132 gradually increases in the upstream to downstream direction. The primary air straight section 131 is provided with a primary air inlet hole communicating with the primary air passage 1311. The primary air inlet pipe 14 is connected to the primary air straight section 131, and the inner cavity of the primary air inlet pipe 14 is connected to the primary air passage 1311 through the primary air inlet hole.

[0042] Optionally, as Figure 1 and Figure 2 shown, the igniter 11 is cylindrical. The igniter 11 and the primary air cylinder 13 are both arranged in the front-rear direction, and the central axis of the primary air cylinder 13 is coaxial with the central axis of the igniter 11. The rear end of the primary air straight section 131 is connected to the front end of the primary air diffuser section 132. The cross-sectional area of the primary air diffuser section 132 gradually increases in the front-to-back direction, and the angle between the extending direction of the peripheral wall of the primary air diffuser section 132 and the axial direction of the primary air diffuser section 132 is greater than 0 degree and less than or equal to 45 degrees. The primary air straight section 131 is sleeved outside the igniter 11 and is spaced apart from the igniter 11 in the inner and outer directions. The ignition end (rear end) of the igniter 11 is located inside the primary air straight section 131, and the ignition end of the igniter 11 is flush with the rear end of the primary air straight section 131. The front end of the igniter 11 is located outside the primary air straight section 131.

[0043] The primary air seal ring 12 is sleeved on the igniter 11. The primary air seal ring 12 is located on the front side of the primary air straight section 131. The rear wall surface of the primary air seal ring 12 is detachably connected to the front end of the primary air straight section 131 to block the opening at the front end of the primary air straight section 131. The part of the igniter 11 located inside the primary air straight section 131, the primary air straight section 131, and the primary air seal ring 12 together define the primary air passage 1311. The inner cavity of the primary air diffuser section 132 is a stable combustion cavity 1321. The rear end of the primary air passage 1311 is connected to the front end of the stable combustion cavity 1321.

[0044] The peripheral wall of the primary air straight section 131 is provided with primary air inlet holes, which are located at the front of the primary air straight section 131. The primary air inlet holes extend radially along the primary air straight section 131 and communicate with the primary air passage 1311. The primary air input pipe 14 is arranged radially along the primary air straight section 131. One end of the primary air input pipe 14 close to the primary air straight section 131 is connected to the hole wall of the primary air inlet hole, so that the inner cavity of the primary air input pipe 14 is connected to the primary air passage 1311 through the primary air inlet hole.

[0045] It can be understood that, as Figure 3 shown, the primary air passes through the primary air input pipe 14 and is transported to the primary air passage 1311 through the primary air inlet hole. The primary air flows into the stable combustion chamber 1321 along the extension direction of the primary air passage 1311. Under the separation effect of the outlet air flow of the primary air passage 1311 and the diffusion effect of the wall surface of the stable combustion chamber 1321, a primary air recirculation zone 100 is formed at the outlet of the stable combustion chamber 1321 (the opening at the rear end of the stable combustion chamber 1321). Moreover, by inputting pulverized coal into the primary air input pipe 14, the primary air transports the pulverized coal into the stable combustion chamber 1321 and is ignited by the igniter 11.

[0046] In some embodiments, as Figures 1 to 3 shown, a first axial impeller assembly 15 is provided in the primary air passage 1311. The first axial impeller assembly 15 is used to make the primary air form a rotating air flow with tangential velocity after passing through the first axial impeller assembly 15. The first axial impeller assembly 15 includes a first blade ring and a plurality of first axial blades. The first blade ring is sleeved on the igniter 11. The plurality of first axial blades are arranged at intervals along the circumferential direction of the first blade ring. There is a gap of 2-5 mm between the blade tips of the first axial blades and the inner wall of the primary air straight section 131.

[0047] Optionally, as Figures 1 to 3 shown, the first axial impeller assembly 15 is located at the rear end of the primary air passage 1311, so that after the primary air passes through the first axial impeller assembly 15, the primary air rotates around the axis of the primary air cylinder 13 and enters the stable combustion chamber 1321 to form a swirling primary air recirculation zone 100.

[0048] Furthermore, the first blade ring is sleeved on the ignition end of the igniter 11. The blade roots of the first axial blades are connected to the outer peripheral wall of the first blade ring. The plurality of first axial blades are arranged at intervals along the circumferential direction of the first blade ring. The gap between the blade tips of the first axial blades and the inner wall of the primary air straight section 131 is 2 mm, 3 mm, 4 mm or 5 mm. Moreover, the detachable connection relationship between the primary air seal ring 12 and the primary air straight section 131 enables the igniter 11 to be taken out from the primary air straight section 131, which is convenient for overhauling and replacing the igniter 11 and cleaning and replacing the first axial impeller assembly 15.

[0049] In some embodiments, as Figures 1 to 3 shown, the burner body 1 further includes a gas cylinder 16, a first gas sealing ring 17, a second gas sealing ring 18, and a gas inlet pipe 19. The gas cylinder 16 is sleeved outside the primary air cylinder 13, and the primary air cylinder 13 and the gas cylinder 16 are spaced apart in the inner and outer directions. The gas cylinder 16 includes a connected gas straight section 161 and a gas diffusion section 162. The gas diffusion section 162 is located downstream of the gas straight section 161, and the cross-sectional area of the gas diffusion section 162 gradually increases in the upstream to downstream direction. The inner end of the first gas sealing ring 17 is connected to the primary air cylinder 13, the outer end of the first gas sealing ring 17 is connected to the gas straight section 161, the inner end of the second gas sealing ring 18 is connected to the primary air cylinder 13, the outer end of the second gas sealing ring 18 is connected to the gas diffusion section 162, and the primary air cylinder 13, the gas straight section 161, the gas diffusion section 162, the first gas sealing ring 17, and the second gas sealing ring 18 define a gas passage 1611. A gas injection hole 1621 is provided on the gas diffusion section 162. A gas inlet hole and a relief hole communicating with the gas passage 1611 are provided on the gas straight section 161. The gas inlet pipe 19 is connected to the gas straight section 161, and the inner chamber of the gas inlet pipe 19 is connected to the gas passage 1611 through the gas inlet hole. The primary air inlet pipe 14 penetrates through the relief hole.

[0050] Optionally, as Figure 1 and Figure 2 shown, the central axis of the gas cylinder 16 is coaxial with the central axis of the primary air cylinder 13. The rear end of the gas straight section 161 is connected to the front end of the gas diffusion section 162. The cross-sectional area of the gas diffusion section 162 gradually increases in the front to back direction. The angle between the extending direction of the wall surface of the gas diffusion section 162 and the axis of the gas diffusion section 162 is greater than 20 degrees and less than or equal to 45 degrees.

[0051] The front and rear ends of the gas straight section 161 are flush with the front and rear ends of the primary air straight section 131. The gas straight section 161 is sleeved outside the primary air straight section 131 and is spaced apart in the inner and outer directions. The inner end of the first gas sealing ring 17 is connected to the front end of the primary air straight section 131, and the outer end of the first gas sealing ring 17 is connected to the front end of the gas straight section 161.

[0052] The front and rear ends of the gas diffusion section 162 are flush with the front and rear ends of the primary air diffusion section 132. The gas diffusion section 162 is sleeved outside the primary air diffusion section 132 and is spaced apart in the inner and outer directions. The inner end of the second gas sealing ring 18 is connected to the rear end of the primary air diffusion section 132, and the outer end of the second gas sealing ring 18 is connected to the outer end of the gas diffusion section 162.

[0053] Thus, the primary air straight section 131, the primary air diffuser section 132, the fuel gas straight section 161, the fuel gas diffuser section 162, the first fuel gas sealing ring 17 and the second fuel gas sealing ring 18 jointly define a fuel gas passage 1611.

[0054] Fuel gas injection holes 1621 are formed in the circumferential wall of the fuel gas diffuser section 162. The included angle between the extending direction of the fuel gas injection holes 1621 and the axial direction of the fuel gas diffuser section 162 is greater than 45 degrees and less than 135 degrees. Fuel gas inlet holes and relief holes are formed in the circumferential wall of the fuel gas straight section 161. The fuel gas inlet holes and the relief holes both extend along the radial direction of the fuel gas straight section 161. The fuel gas inlet holes and the relief holes are both located at the front part of the fuel gas straight section 161, and the fuel gas inlet holes and the relief holes are spaced apart from each other along the circumferential direction of the fuel gas straight section 161.

[0055] The fuel gas input pipe 19 is arranged along the radial direction of the fuel gas straight section 161. One end of the fuel gas input pipe 19 close to the fuel gas straight section 161 is connected to the hole wall of the fuel gas inlet hole, so that the internal cavity of the fuel gas input pipe 19 is communicated with the fuel gas passage 1611 through the fuel gas inlet hole. The relief hole and the primary air inlet hole correspond to each other in the inner and outer directions. The primary air input pipe 14 is hermetically penetrated through the relief hole. One end of the primary air input pipe 14 away from the primary air straight section 131 is located outside the fuel gas straight section 161.

[0056] It can be understood that, as Figure 3 shown, the fuel gas passes through the fuel gas input pipe 19 and is conveyed into the fuel gas passage 1611 through the fuel gas inlet hole. The fuel gas flows to the fuel gas injection holes 1621 along the extending direction of the fuel gas passage 1611. Due to the blocking effect of the second fuel gas sealing ring 18, the fuel gas is ejected through the fuel gas injection holes 1621.

[0057] In some embodiments, as Figure 1 and Figure 2 shown, a first fastener 20 is further included. A first mounting hole is formed in the primary air sealing ring 12, and a second mounting hole is formed in the first fuel gas sealing ring 17. The first fastener 20 is sequentially engaged with the first mounting hole and the second mounting hole.

[0058] Optionally, as Figure 1 and Figure 2 shown, the first fastener 20 is a screw, and both the first mounting hole and the second mounting hole are threaded holes. The first mounting hole penetrates through the front and rear wall surfaces of the primary air sealing ring 12 in the front and rear direction. The second mounting hole is a blind hole, and the second mounting hole is formed in the front wall surface of the first fuel gas sealing ring 17. The first fastener 20 penetrates through the first mounting hole, and the rear end of the first fastener 20 is located in the second mounting hole. The first fastener 20 is threadedly engaged with the first mounting hole and the second mounting hole respectively, so that the primary air sealing ring 12 and the first fuel gas sealing ring 17 are detachably connected.

[0059] Further, the first fasteners 20, the first mounting holes, and the second mounting holes are all multiple, and the multiple first fasteners 20 correspond to the multiple first mounting holes one by one, and the multiple first mounting holes correspond to the multiple second mounting holes one by one. The first mounting holes are circumferentially spaced along the primary air seal ring 12, and the second mounting holes are circumferentially spaced along the first gas seal ring 17. The first fasteners 20 are fitted into the corresponding first and second mounting holes, thereby improving the connection stability between the primary air seal ring 12 and the first gas seal ring 17.

[0060] In some embodiments, as Figures 1 to 3 shown, the burner body 1 further includes a secondary air cylinder 21, a secondary air seal ring 22, and a secondary air inlet pipe 23. The secondary air cylinder 21 includes a connected secondary air straight section 211 and a secondary air diffuser section 212. The secondary air diffuser section 212 is located downstream of the secondary air straight section 211. The secondary air straight section 211 is sleeved on at least a part of the gas cylinder 16, and the gas cylinder 16 and the secondary air straight section 211 are spaced apart in the inner and outer directions. The inner end of the secondary air seal ring 22 is connected to the gas cylinder 16, and the outer end of the secondary air seal ring 22 is connected to the secondary air straight section 211. The gas cylinder 16, the secondary air straight section 211, and the secondary air seal ring 22 define a secondary air passage 2111. The internal cavity of the secondary air diffuser section 212 is a pre-combustion chamber 2121, and the cross-sectional area of the secondary air diffuser section 212 gradually increases in the upstream to downstream direction. The secondary air straight section 211 is provided with a secondary air inlet hole communicating with the secondary air passage 2111. The secondary air inlet pipe 23 is connected to the secondary air straight section 211, and the internal cavity of the secondary air inlet pipe 23 is connected to the secondary air passage 2111 through the secondary air inlet hole. The included angle between the extending direction of the gas injection hole 1621 and the extending direction of the secondary air passage 2111 is 45° - 135°.

[0061] Optionally, as Figure 1 and Figure 2 shown, the central axis of the secondary air cylinder 21 is coaxial with the central axis of the gas cylinder 16. The rear end of the secondary air straight section 211 is connected to the front end of the secondary air diffuser section 212. The cross-sectional area of the secondary air diffuser section 212 gradually increases in the front to back direction. The included angle between the extending direction of the wall surface of the secondary air diffuser section 212 and the axis of the secondary air diffuser section 212 is greater than 0° and less than or equal to 15°. The internal cavity of the secondary air diffuser section 212 is the pre-combustion chamber 2121.

[0062] The rear end of the straight section 211 of the secondary air is flush with the rear end of the gas diffusion section 162. The straight section 211 of the secondary air is sleeved outside the straight section 161 and the gas diffusion section 162 of the gas and is spaced apart in the inner and outer directions. The inner end of the secondary air seal ring 22 is connected to the outer peripheral wall of the straight section 161 of the gas, and the outer end of the secondary air seal ring 22 is connected to the front end of the straight section 211 of the secondary air. The secondary air seal ring 22 is located at the rear side of the primary air input pipe 14 and the gas input pipe 19. The part of the straight section 161 of the gas located inside the straight section 211 of the secondary air, the gas diffusion section 162, the straight section 211 of the secondary air, and the secondary air seal ring 22 jointly define a secondary air passage 2111. Thus, the rear end of the stable combustion chamber 1321 and the rear end of the secondary air passage 2111 are both connected and communicated with the front end of the pre-combustion chamber 2121.

[0063] Secondary air inlet holes are formed in the peripheral wall of the straight section 211 of the secondary air. The secondary air inlet holes extend along the radial direction of the straight section 211 of the secondary air, and the secondary air inlet holes are located in the front part of the straight section 211 of the secondary air. The secondary air input pipe 23 is arranged along the radial direction of the straight section 211 of the secondary air. One end of the secondary air input pipe 23 close to the straight section 211 of the secondary air is connected to the hole wall of the secondary air inlet hole, so that the inner cavity of the secondary air input pipe 23 is connected and communicated with the secondary air passage 2111 through the secondary air inlet hole.

[0064] The gas passage 1611 is connected and communicated with the secondary air passage 2111 through the gas injection holes 1621. The included angle between the extending direction of the gas injection holes 1621 and the extending direction of the secondary air passage 2111 is 45° - 135°, so that the gas is tangentially injected into the secondary air flow.

[0065] It can be understood that, as Figure 3 shown, the secondary air is transported to the inside of the secondary air passage 2111 through the secondary air input pipe 23 and the secondary air inlet holes. The secondary air flows into the pre-combustion chamber 2121 along the extending direction of the secondary air passage 2111, and under the action of the blunt body recirculation of the gas passage 1611 (the gas diffusion section 162 is a blunt body) and the diffusion action of the wall surface of the pre-combustion chamber 2121, a secondary air recirculation zone 200 is formed in the pre-combustion chamber 2121. And, the gas tangentially injected into the secondary air passage 2111 through the gas injection holes 1621 enables the secondary air and the gas to be quickly and evenly mixed, and transports the gas to the pre-combustion chamber 2121, and is ignited by the igniter 11.

[0066] In addition, when the secondary air flows in the secondary air passage 2111 to the gas diffusion section 162, due to the gas diffusion section 162, the cross-sectional area of the secondary air passage 2111 gradually decreases in the front-to-back direction, causing the velocity of the secondary air to continuously increase. Moreover, the area of the secondary air recirculation zone 200 formed by the secondary air in the pre-combustion chamber 2121 is larger than the area of the primary air recirculation zone 100. The gas velocity at the gas nozzle is 100 - 300 m / s, while when the secondary air flows outside the gas diffusion section 162, the velocity is 30 - 60 m / s. The high-speed gas fuel and the secondary air are quickly mixed at a certain intersection angle, which is beneficial to reducing the generated prompt (instantaneous) NOx. After mixing, the distribution of the gas and the secondary air is relatively uniform, which is also beneficial to reducing the thermal NOx generated by local high temperatures.

[0067] In some embodiments, as Figure 1 and Figure 2 shown, the secondary air seal ring 22 includes a first seal ring portion 221 and a second seal ring portion 222 that are detachably connected. The inner end of the first seal ring portion 221 is connected to the gas straight section 161, and the outer end of the second seal ring portion 222 is connected to the secondary air straight section 211. The pulverized coal and gas dual-fuel burner further includes a second fastener 24. A third mounting hole is provided on the first seal ring portion 221, and a fourth mounting hole is provided on the second seal ring portion 222. The second fastener 24 cooperates with the third mounting hole and the fourth mounting hole in sequence.

[0068] Optionally, as Figure 1 and Figure 2 shown, the inner end of the first seal ring portion 221 is connected to the outer peripheral wall of the gas straight section 161, the outer end of the second seal ring portion 222 is connected to the front end of the secondary air straight section 211, and the diameter of the central through hole of the second seal ring portion 222 is larger than the diameter of the gas diffusion section 162, so that the gas diffusion section 162 can pass through the central through hole of the second seal ring portion 222.

[0069] The second fastener 24 is a screw, and both the third mounting hole and the fourth mounting hole are threaded holes. The third mounting hole penetrates through the front and rear wall surfaces of the first seal ring portion 221 in the front-to-back direction. The fourth mounting hole is a blind hole and is provided on the front wall surface of the second seal ring portion 222. The second fastener 24 penetrates through the third mounting hole, and the rear end of the second fastener 24 is located in the fourth mounting hole. The second fastener 24 is threadedly engaged with the third mounting hole and the fourth mounting hole respectively, so that the first seal ring portion 221 and the second seal ring portion 222 are detachably connected, enabling the gas cylinder 16 and the primary air cylinder 13 to be taken out from the secondary air cylinder 21, facilitating the cleaning of the gas nozzle holes 1621 and the maintenance and replacement of the gas cylinder 16 and the primary air cylinder 13.

[0070] Further, the second fasteners 24, the third mounting holes, and the fourth mounting holes are all multiple, and the multiple second fasteners 24 correspond to the multiple third mounting holes one by one, and the multiple third mounting holes correspond to the multiple fourth mounting holes one by one. The third mounting holes are circumferentially spaced along the first sealing ring portion 221, the fourth mounting holes are circumferentially spaced along the second sealing ring portion 222, and the second fasteners 24 are fitted in the corresponding third and fourth mounting holes, thereby improving the connection stability between the first sealing ring portion 221 and the second sealing ring portion 222.

[0071] In some embodiments, as Figures 1 to 3 shown, the burner body 1 further includes a tertiary air cylinder 25, a tertiary air seal ring 26, and a tertiary air inlet pipe 27. The tertiary air cylinder 25 is sleeved on at least a part of the secondary air cylinder 21, and the secondary air cylinder 21 and the tertiary air cylinder 25 are spaced apart in the inner and outer directions. The tertiary air cylinder 25 includes a connected tertiary air straight section 251 and a tertiary air contraction section 252. The tertiary air contraction section 252 is located downstream of the tertiary air straight section 251, and the cross-sectional area of the tertiary air contraction section 252 gradually decreases in the upstream to downstream direction. The inner end of the tertiary air seal ring 26 is connected to the secondary air cylinder 21, the outer end of the tertiary air seal ring 26 is connected to the tertiary air straight section 2511, and the secondary air cylinder 21, the tertiary air seal ring 26, and the tertiary air cylinder 25 define a tertiary air passage 2511. A tertiary air inlet hole communicating with the tertiary air passage 2511 is provided on the tertiary air straight section 251, the tertiary air inlet pipe 27 is connected to the tertiary air straight section 2511, and the internal cavity of the tertiary air inlet pipe 27 is connected to the tertiary air passage 2511 through the tertiary air inlet hole.

[0072] Optionally, as Figure 1 and Figure 2 shown, the central axis of the tertiary air cylinder 25 is coaxial with the central axis of the secondary air cylinder 21. The rear end of the tertiary air straight section 251 is connected to the front end of the tertiary air contraction section 252, the cross-sectional area of the tertiary air contraction section 252 gradually decreases in the front to back direction, and the angle between the extending direction of the wall surface of the tertiary air contraction section 252 and the axis of the tertiary air contraction section 252 is greater than 5 degrees and less than or equal to 15 degrees. The inner end of the tertiary air seal ring 26 is connected to the outer peripheral wall of the secondary air straight section 211, and the outer end of the tertiary air seal ring 26 is connected to the inner peripheral wall of the tertiary air straight section 251.

[0073] A tertiary air inlet hole is formed in the peripheral wall of the tertiary air straight section 251. The tertiary air inlet hole extends radially along the tertiary air straight section 251 and is located at the front part of the tertiary air straight section 251. The tertiary air inlet pipe 27 is arranged radially along the tertiary air straight section 251, and one end of the tertiary air inlet pipe 27 close to the tertiary air straight section 251 is connected to the hole wall of the tertiary air inlet hole, so that the internal cavity of the tertiary air inlet pipe 27 is connected to the tertiary air passage 2511 through the tertiary air inlet hole.

[0074] When the air-powder dual-fuel burner of the embodiment of the present invention is installed on a boiler, the tertiary air contraction section 252 is located in the furnace of the boiler. The tertiary air contraction section 252 is conducive to the recirculation of the flue gas in the furnace at the outlet of the air-powder dual-fuel burner of the embodiment of the present invention, thereby reducing the generation of nitrogen oxides.

[0075] Further, as Figure 1 and Figure 2 shown, the secondary air cylinder 21 further includes a secondary air contraction section 213. The secondary air contraction section 213 is located downstream of the secondary air diffusion section 212 and is connected to the secondary air diffusion section 212. The cross-sectional area of the secondary air contraction section 213 gradually decreases in the upstream-to-downstream direction, and the two ends of the secondary air contraction section 213 and the tertiary air contraction section 252 are flush.

[0076] Optionally, as Figure 1 and Figure 2 shown, the front end of the secondary air contraction section 213 is connected to the rear end of the secondary air diffusion section 212. The cross-sectional area of the secondary air contraction section 213 gradually decreases in the front-to-back direction. The angle between the extending direction of the wall surface of the secondary air contraction section 213 and the axis of the secondary air contraction section 213 is greater than 5 degrees and less than or equal to 15 degrees. The rear end of the secondary air diffusion section 212 is flush with the rear end of the tertiary air straight section 251, and the front and rear ends of the secondary air contraction section 213 are flush with the front and rear ends of the tertiary air contraction section 252.

[0077] Thus, the secondary air diffusion section 212, the secondary air contraction section 213, the tertiary air straight section 2511, the tertiary air contraction section 252, and the tertiary air seal ring 26 jointly define the tertiary air passage 2511. It can be understood that, as Figure 3 shown, the flame burning in the pre-combustion chamber 2121 follows the secondary air flow, and under the gathering effect of the secondary air contraction section 213, the flame is accelerated and ejected from the outlet at the rear end of the secondary air contraction section 213. The high-speed jet flame flow is also conducive to the internal circulation of the flue gas in the boiler furnace, thereby reducing the generation of nitrogen oxides.

[0078] The tertiary air passes through the tertiary air input pipe 27 and is delivered to the tertiary air passage 2511 through the tertiary air inlet holes. Under the action of the tertiary air contraction section 252, the tertiary air flows in the direction of the flame ejected from the outlet of the secondary air contraction section 213, thereby preventing the phenomenon of the flame ejected from the outlet of the secondary air contraction section 213 from flaring.

[0079] In some embodiments, as Figures 1 to 3As shown in the figure, a second axial impeller assembly 28 is provided in the tertiary air passage 2511. The second axial impeller assembly 28 is configured to cause the tertiary air to form a swirling air flow with a tangential velocity after passing through the second axial impeller assembly 28. The second axial impeller assembly 28 includes a second vane ring and a plurality of second axial vanes. The second vane ring is sleeved on the secondary air contraction section 213, and the plurality of second axial vanes are circumferentially spaced apart on the second vane ring. There is a gap of 3-10 mm between the tip of the second axial vane and the inner wall of the tertiary air contraction section 252.

[0080] Optionally, as Figures 1 to 3 shown, the second axial impeller assembly 28 is located at the rear end of the tertiary air passage 2511, such that after the tertiary air passes through the second axial impeller assembly 28, the tertiary air rotates around the axis of the tertiary air cylinder 25. Further, the second vane ring is sleeved on the secondary air contraction section 213, the root of the second axial vane is connected to the outer peripheral wall of the second vane ring, the plurality of second axial vanes are circumferentially spaced apart, and the gap between the tip of the second axial vane and the inner wall of the tertiary air contraction section 252 is 3-10 mm, so as to leave an expansion amount for the secondary air contraction section 213 adjacent to the flame and prevent extrusion deformation between the second axial impeller assembly 28 and the tertiary air contraction section 252.

[0081] It can be understood that since the gas nozzle is opened on the wall surface of the gas diffusion section 162, the gas fuel concentration near the wall surface of the pre-combustion chamber 2121 is higher than the fuel concentration at the center of the pre-combustion chamber 2121, and this trend remains until the outlet of the secondary air contraction section 213. The tertiary air supplies the oxygen required for combustion after the outlet of the secondary air contraction section 213. Therefore, at the place where the flame of the tertiary air and the outlet of the secondary air contraction section 213 first come into contact, it is a "three-high region" with high temperature, high fuel concentration, and high oxygen content. That is, the combustion finally forms a ring-shaped flame as Figure 4 shown near the outlet of the pulverized coal and gas dual-fuel burner of the embodiment of the present invention, and it is also the position where NOx is most likely to be generated. Therefore, the tertiary air needs to be mixed with recycled flue gas to reduce the oxygen content, so that the flue gas is just mixed into the position of the ring-shaped flame, and the oxygen concentration of the tertiary air is not greater than the oxygen concentration of the secondary air, further reducing the local high temperature peak.

[0082] In addition, the flame length at the outlet of the burner can be controlled by controlling the ratio of the secondary air and the tertiary air. As Figure 5As shown, with the total air distribution volume remaining unchanged, the schematic diagrams of the burner outlet flames with the secondary air and tertiary air ratios being 0.3, 0.5, 1, 2, and 3 respectively. When the air volume of the secondary air is less than that of the tertiary air, the flame at the burner outlet is shorter. When the air volumes of the secondary air and the tertiary air are comparable, the flame length reaches the maximum value. When the air volume of the secondary air is greater than that of the tertiary air, the restraining effect of the tertiary air on the flame weakens, and the flame becomes thicker and shorter. Therefore, the air-powder dual-fuel burner of the embodiment of the present invention can adapt to different furnace sizes and can also adjust the flame size and temperature distribution in the furnace under different loads.

[0083] The following specifically describes three usage states of the air-powder dual-fuel burner of the embodiment of the present invention.

[0084] When burning pulverized coal fuel alone:

[0085] Connect the outlet of the air-powder dual-fuel burner of the embodiment of the present invention to the furnace of the boiler, and send the primary air, secondary air, and tertiary air required for igniting the pulverized coal fuel combustion through the primary air passage 1311, secondary air passage 2111, and tertiary air passage 2511 respectively. Turn on the igniter 11 and confirm that the ignition fuel (gas or oil) has been ignited. Pass pulverized coal into the primary air through an external powder conveying device, and enter the stable combustion chamber 1321 through the primary air input pipe 14, primary air inlet hole, primary air passage 1311, and the first axial impeller assembly 15, where it is ignited and continuously and stably burned under the action of the primary air recirculation zone 100 and the secondary air recirculation zone 200.

[0086] After confirming that the fed pulverized coal fuel is ignited, adjust the supply amount of the pulverized coal fuel and the air volumes of the primary air, secondary air, and tertiary air so that the air-powder dual-fuel burner of the embodiment of the present invention reaches the required load. Moreover, the oxygen content of the tertiary air can be reduced by mixing recycled flue gas into the tertiary air to reduce the nitrogen oxides generated during the combustion process.

[0087] At this time, the primary air is pure air, accounting for 5% - 30% of the theoretical air volume. The secondary air is pure air, accounting for 30% - 80% of the theoretical air volume. The tertiary air is pure air or a mixed gas of air mixed with recycled flue gas, with a total amount of 30% - 80% of the theoretical air volume and an oxygen content of 10% - 21%.

[0088] When burning gas alone:

[0089] Dock the outlet of the gas-powder dual-fuel burner according to the embodiment of the present invention with the furnace of the boiler, and send the primary air, secondary air, and tertiary air required for gas combustion ignition into the primary air passage 1311, secondary air passage 2111, and tertiary air passage 2511 respectively. Turn on the igniter 11 and confirm that the ignition fuel has been ignited. Pass gas into the gas passage 1611 through an external gas supply device. The gas passes through the gas input pipe 19, gas inlet holes, gas passage 1611, and gas injection holes 1621, is sprayed into the secondary air passage 2111, and is premixed with the secondary air. Then, part of the gas flows into the secondary air recirculation zone 200 and is ignited. After being ignited, it continues to burn stably under the action of the secondary air recirculation zone 200 and the primary air recirculation zone 100.

[0090] After confirming that the introduced gas is ignited, adjust the supply amount of the gas and the air volumes of the primary air, secondary air, and tertiary air so that the gas-powder dual-fuel burner according to the embodiment of the present invention reaches the required load. Moreover, by introducing recycled flue gas into the secondary air and tertiary air, the oxygen content of the secondary air and tertiary air can be reduced to reduce the nitrogen oxides generated during the combustion process.

[0091] At this time, the primary air is pure air, accounting for 5%-30% of the theoretical air volume. The secondary air is a mixed gas of air and recycled flue gas, accounting for 30%-80% of the theoretical air volume, and the oxygen content is 17%-21%. The tertiary air is a mixed gas of air and recycled flue gas, with a total amount of 30%-80% of the theoretical air volume, and the oxygen content is 15%-21%.

[0092] When pulverized coal and gas are mixed and burned:

[0093] Dock the outlet of the gas-powder dual-fuel burner according to the embodiment of the present invention with the furnace of the boiler, and send the primary air, secondary air, and tertiary air required for gas-powder mixed combustion ignition into the primary air passage 1311, secondary air passage 2111, and tertiary air passage 2511 respectively. Turn on the igniter 11 and confirm that the ignition fuel has been ignited.

[0094] Pass gas into the gas passage 1611 through an external gas supply device. The gas passes through the gas input pipe 19, gas inlet holes, gas passage 1611, and gas injection holes 1621, is sprayed into the secondary air passage 2111, and is premixed with the secondary air. Then, part of the gas flows into the secondary air recirculation zone 200 and is ignited. After confirming that the introduced gas is ignited, pass pulverized coal into the primary air through an external powder conveying device. The pulverized coal passes through the primary air input pipe 14, primary air inlet holes, primary air passage 1311, and the first axial impeller assembly 15, and enters the stable combustion chamber 1321 and is ignited. The gas and pulverized coal continue to burn stably under the action of the primary air recirculation zone 100 and the secondary air recirculation zone 200.

[0095] After confirming that the hybrid fuel is ignited, adjust the supply amounts of the gas and pulverized coal, as well as the air volumes of the primary air, secondary air, and tertiary air in proportion, so that the gas-pulverized coal dual-fuel burner in the embodiment of the present invention reaches the required load. Moreover, by introducing recycled flue gas into the secondary air and tertiary air, the oxygen content in the secondary air and tertiary air can be reduced to decrease the nitrogen oxides generated during the combustion process.

[0096] At this time, the primary air is pure air, accounting for 5% - 30% of the theoretical air volume. The secondary air is a mixed gas of air and recycled flue gas, accounting for 30% - 80% of the theoretical air volume, and the oxygen content is 17% - 21%. The tertiary air is a mixed gas of air and recycled flue gas, with a total amount of 30% - 80% of the theoretical air volume, and the oxygen content is 15% - 21%.

[0097] In summary, when the gas-pulverized coal dual-fuel burner in the embodiment of the present invention burns pulverized coal alone or burns a mixture of pulverized coal and gas, the NOx can be controlled at 150 - 250 mg / m 3 (@6%O 2 ) When burning gas alone, if no recycled flue gas is introduced into the secondary air and tertiary air, NOx < 80 mg / m 3 (@3.5%O 2 ) If recycled flue gas is introduced into the secondary air and tertiary air, the oxygen content in the secondary air is not more than 19%, and the oxygen content in the tertiary air is not more than 18%, then NOx < 30 mg / m 3 (@3.5%O 2 )

[0098] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 thus should not be construed as a limitation to the present invention.

[0099] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0100] In the present invention, unless otherwise clearly specified or limited, terms such as "installed", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication between two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0101] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0102] In the present invention, terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0103] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the protection scope of the present invention.

Claims

1. A gas-powder dual-fuel burner, characterized in that, it includes: a burner body, the burner body having a primary air passage, a stable combustion chamber, a gas passage, gas injection holes, a secondary air passage, a pre-combustion chamber and a tertiary air passage, the primary air passage, the gas passage and the secondary air passage being sequentially and spaced apart from inside to outside along the radial direction of the primary air passage; the stable combustion chamber is located downstream of the primary air passage and is in communication with the primary air passage, the cross-sectional area of the stable combustion chamber gradually increasing in the upstream to downstream direction, and the primary air can form a primary air recirculation zone at the outlet of the stable combustion chamber; the gas passage is connected to the secondary air passage through the gas injection holes, and there is an included angle between the extending direction of the gas injection holes and the extending direction of the secondary air passage; the pre-combustion chamber is located downstream of the secondary air passage and the stable combustion chamber and is in communication with the secondary air passage and the stable combustion chamber, the cross-sectional area of the pre-combustion chamber gradually increasing in the upstream to downstream direction, and the secondary air can form a secondary air recirculation zone in the pre-combustion chamber, the secondary air recirculation zone being located downstream of the primary air recirculation zone and intersecting with the primary air recirculation zone; the tertiary air passage is located outside the pre-combustion chamber, and the outlet of the tertiary air passage extends in a direction approaching the central axis of the pre-combustion chamber; the burner body includes: an igniter; a primary air seal ring sleeved on the igniter; a primary air cylinder body, the primary air cylinder body including a connected primary air straight section and a primary air diffusion section, the primary air diffusion section being located downstream of the primary air straight section, the primary air straight section sleeved on at least part of the outside of the igniter, the igniter and the primary air straight section being spaced apart in the inner and outer directions, the primary air seal ring being detachably connected to the primary air straight section, the igniter, the primary air straight section and the primary air seal ring defining the primary air passage, the inner chamber of the primary air diffusion section being the stable combustion chamber, and the cross-sectional area of the primary air diffusion section gradually increasing in the upstream to downstream direction; a primary air input pipe, the primary air straight section being provided with a primary air inlet hole communicating with the primary air passage, the primary air input pipe being connected to the primary air straight section, and the inner chamber of the primary air input pipe being in communication with the primary air passage through the primary air inlet hole; the burner body further includes: a gas cylinder body sleeved outside the primary air cylinder body, the primary air cylinder body and the gas cylinder body being spaced apart in the inner and outer directions, the gas cylinder body including a connected gas straight section and a gas diffusion section, the gas diffusion section being located downstream of the gas straight section, and the cross-sectional area of the gas diffusion section gradually increasing in the upstream to downstream direction; A first gas seal ring and a second gas seal ring, an inner end of the first gas seal ring is connected to the primary air cylinder body, an outer end of the first gas seal ring is connected to the gas straight section, an inner end of the second gas seal ring is connected to the primary air cylinder body, an outer end of the second gas seal ring is connected to the gas diffusion section, the primary air cylinder body, the gas straight section, the gas diffusion section, the first gas seal ring and the second gas seal ring define the gas passage, and the gas injection holes are arranged on the gas diffusion section; A gas input pipe, a gas inlet hole and a relief hole communicating with the gas passage are arranged on the gas straight section, the gas input pipe is connected to the gas straight section, and an internal chamber of the gas input pipe is connected to the gas passage through the gas inlet hole, and the primary air input pipe penetrates through the relief hole.

2. The pulverized coal and gas dual-fuel burner according to claim 1, characterized in that a first axial impeller assembly is provided in the primary air passage, and the first axial impeller assembly is used for enabling the primary air to form a swirling air flow with a tangential velocity after passing through the first axial impeller assembly; the first axial impeller assembly includes a first blade ring and a plurality of first axial blades, the first blade ring is sleeved on the igniter, the plurality of first axial blades are arranged on the first blade ring at intervals in the circumferential direction of the first blade ring, and there is a gap of 2-5 mm between the blade tips of the first axial blades and the inner wall of the primary air straight section.

3. The pulverized coal and gas dual-fuel burner according to claim 1, characterized in that it further includes a first fastener, a first mounting hole is provided on the primary air seal ring, a second mounting hole is provided on the first gas seal ring, and the first fastener is sequentially matched with the first mounting hole and the second mounting hole.

4. The pulverized coal and gas dual-fuel burner according to claim 1, characterized in that the burner body further includes: a secondary air cylinder body and a secondary air seal ring, the secondary air cylinder body includes a connected secondary air straight section and a secondary air diffusion section, the secondary air diffusion section is located downstream of the secondary air straight section, the secondary air straight section is sleeved on at least part of the outer side of the gas cylinder body, the gas cylinder body and the secondary air straight section are spaced apart in the inner and outer directions, an inner end of the secondary air seal ring is connected to the gas cylinder body, an outer end of the secondary air seal ring is connected to the secondary air straight section, the gas cylinder body, the secondary air straight section and the secondary air seal ring define the secondary air passage, an internal chamber of the secondary air diffusion section is the pre-combustion chamber, and a cross-sectional area of the secondary air diffusion section gradually increases in the upstream to downstream direction; a secondary air input pipe, a secondary air inlet hole communicating with the secondary air passage is provided on the secondary air straight section, the secondary air input pipe is connected to the secondary air straight section, and an internal chamber of the secondary air input pipe is connected to the secondary air passage through the secondary air inlet hole; an included angle between an extending direction of the gas injection holes and an extending direction of the secondary air passage is 45°-135°.

5. The pulverized coal and gas dual-fuel burner according to claim 4, characterized in that The secondary air seal ring includes a first seal ring part and a second seal ring part that are detachably connected. The inner end of the first seal ring part is connected to the gas straight section, and the outer end of the second seal ring part is connected to the secondary air straight section; The pulverized coal and gas dual-fuel burner further includes a second fastener. The first seal ring part is provided with a third mounting hole, and the second seal ring part is provided with a fourth mounting hole. The second fastener cooperates with the third mounting hole and the fourth mounting hole in sequence.

6. The pulverized coal and gas dual-fuel burner according to claim 4, characterized in that, The burner body further includes: A tertiary air cylinder, the tertiary air cylinder sleeved on at least part of the outside of the secondary air cylinder. The secondary air cylinder and the tertiary air cylinder are spaced apart in the inner and outer directions. The tertiary air cylinder includes a connected tertiary air straight section and a tertiary air contraction section. The tertiary air contraction section is located downstream of the tertiary air straight section, and the cross-sectional area of the tertiary air contraction section gradually decreases in the upstream to downstream direction; A tertiary air seal ring, the inner end of the tertiary air seal ring is connected to the secondary air cylinder, and the outer end of the tertiary air seal ring is connected to the tertiary air straight section. The secondary air cylinder, the tertiary air seal ring and the tertiary air cylinder define the tertiary air passage; A tertiary air input pipe, a tertiary air inlet hole communicating with the tertiary air passage is provided on the tertiary air straight section. The tertiary air input pipe is connected to the tertiary air straight section, and the internal cavity of the tertiary air input pipe is connected to the tertiary air passage through the tertiary air inlet hole.

7. The pulverized coal and gas dual-fuel burner according to claim 6, characterized in that, The secondary air cylinder further includes a secondary air contraction section. The secondary air contraction section is located downstream of the secondary air diffusion section and is connected to the secondary air diffusion section. The cross-sectional area of the secondary air contraction section gradually decreases in the upstream to downstream direction, and the two ends of the secondary air contraction section and the tertiary air contraction section are flush.

8. The pulverized coal and gas dual-fuel burner according to claim 7, characterized in that, A second axial impeller assembly is provided in the tertiary air passage. The second axial impeller assembly is used to make the tertiary air form a rotating air flow with a tangential velocity after passing through the second axial impeller assembly; The second axial impeller assembly includes a second blade ring and a plurality of second axial blades. The second blade ring is sleeved on the secondary air contraction section, and the plurality of second axial blades are arranged at intervals along the circumferential direction of the second blade ring on the second blade ring. There is a gap of 3-10 mm between the blade tips of the second axial blades and the inner wall of the tertiary air contraction section.

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