Industrial plasma-assisted combustion turbulent burner

Abstract

The invention relates to an industrial plasma-assisted combustion turbulent burner, and belongs to the technical field of gas burners. The cyclone burner comprises a coaxial circular composite gas conveying pipe formed by sequentially nesting a plurality of pipe bodies from outside to inside and a burning pipe arranged at an exhaust port of the outermost pipe body, a plurality of coaxial annular channels are formed in the composite gas conveying pipe, cyclone blades are arranged in the annular channels, an electrode assembly is arranged in the composite gas conveying pipe, and the electrode assembly is arranged in the burning pipe. A flow guide assembly is arranged at an exhaust port, and a microwave generation assembly is arranged on the combustion pipe. Low-calorific-value fuel gas and air are fed into a combustion area through the composite gas conveying pipe, the low-calorific-value fuel gas in the center of the combustor is ionized through the electrode assembly to generate plasmas, the plasmas are rotationally diffused in the radial direction of the combustion pipe through the flow guide assembly, flames are enhanced through the microwave generation assembly, and the combustion efficiency is improved. The combustion stability is improved; and the emission of nitrogen oxides is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of gas burners, and in particular relates to a swirl burner for industrial plasma-assisted combustion. Background Art

[0002] Traditional swirl burners are widely used in gas turbines, industrial boilers, combustion furnaces and other equipment. The core design of the burner uses swirl blades to induce the air and fuel to swirl, forming a staged combustion mode with a central premixed combustion zone and a peripheral diffusion combustion zone. In the central premixed combustion zone, the fuel and air are premixed and then burned quickly, releasing high-temperature heat; while the diffusion combustion zone achieves full mixing of the fuel and the combustion-supporting gas through swirl action. This type of burner performs well in the clean combustion of conventional fuels such as natural gas and diesel, and has become the mainstream technology in the field of industrial combustion.

[0003] However, when traditional swirl burners are applied to low calorific value fuels such as ammonia, their performance is significantly limited. The volume calorific value of ammonia is only 1 / 5 of that of natural gas, resulting in a high ignition temperature, low combustion rate, and weak flame propagation ability, making it difficult to achieve stable combustion under normal combustion conditions. Specifically, traditional burners have low combustion temperatures and difficulty in stabilizing flames. During the combustion process, there is unburned ammonia and intermediate products, resulting in fuel waste. In addition, the ammonia combustion process tends to produce a large amount of NO x , emission control is difficult. Although existing technologies improve ammonia combustion performance by optimizing swirl intensity, staged fuel injection or premixing ratio adjustment, they are still limited by the slow chemical kinetics of ammonia itself and it is difficult to break through the bottleneck of combustion efficiency and emissions. Summary of the invention

[0004] The object of the present invention is to provide a swirl burner for industrial plasma-assisted combustion in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A swirl burner for plasma-assisted combustion for industrial use, comprising a coaxial circular composite gas delivery pipe formed by multiple tube bodies nested in sequence from outside to inside, and a combustion pipe arranged at the exhaust port of the outermost tube body, wherein multiple coaxial annular channels are formed inside the composite gas delivery pipe, each annular channel is provided with a swirl blade, the annular channels are used to transport low calorific value gas or combustion-supporting gas, and the innermost annular channel is used to transport low calorific value gas. An electrode assembly is arranged inside the composite gas delivery pipe, and a flow guide assembly is arranged at its exhaust port, a circular ring opening is formed between the flow guide assembly and the innermost annular channel, the electrode assembly is used to ionize the low calorific value gas in the innermost annular channel to generate plasma, the flow guide assembly is used to make the plasma diffuse radially along the circular ring opening, and a microwave generating assembly for enhancing the flame is arranged on the combustion pipe.

[0007] As a further optimization scheme of the present invention, the tube body is divided into a peripheral air pipe, a peripheral gas pipe, a central air pipe and a central gas pipe from the outside to the inside, and the annular channel is divided into a peripheral air channel, a peripheral gas channel, a central air channel and a central gas channel. The peripheral air channel is located between the peripheral air pipe and the peripheral gas pipe, the peripheral gas channel is located between the peripheral gas pipe and the central air pipe, the central air channel is located between the central air pipe and the central gas pipe, and the central gas channel is located on the inner side of the central gas pipe.

[0008] As a further optimization scheme of the present invention, the combustion tube includes a combustion stabilizing expansion tube and a furnace, the small diameter end of the combustion stabilizing expansion tube is fixedly arranged at the exhaust port of the peripheral air pipe, and the large diameter end of the combustion stabilizing expansion tube is fixedly arranged at the air inlet of the furnace, and the microwave generating assembly includes a microwave generator, and a microwave antenna 1 arranged on the outside of the combustion stabilizing expansion tube and a microwave antenna 2 arranged on the outside of the furnace.

[0009] As a further optimization scheme of the present invention, the guide assembly includes a positioning column arranged at the center of the exhaust port of the central gas pipe, and a guide plate arranged at one end of the positioning column, and the electrode assembly includes electrode 1 arranged at the other end of the positioning column, and electrode 2 arranged on the wall of the central gas pipe.

[0010] As a further optimization scheme of the present invention, the electrode assembly also includes an electrode three arranged on the wall of the central air pipe, the electrode two is a high-voltage electrode, and an insulating medium layer is provided on the outside of the high-voltage electrode, and the electrode one and electrode three are both low-voltage electrodes.

[0011] As a further optimization solution of the present invention, the guide vane is in an inverted cone shape, and the annular opening is located between the guide vane and the central gas pipe.

[0012] As a further optimization solution of the present invention, the guide assembly also includes a positioning rod penetrating electrode 1, and a support frame fixedly arranged on the inner side of the central gas pipe, and the positioning rod is fixedly arranged between the support frame and the positioning column.

[0013] As a further optimization scheme of the present invention, the guide assembly also includes a rotating shaft that passes through electrode 1 and the positioning column, one end of the rotating shaft is fixedly arranged at the axis center of the guide plate, and a driving blade is provided on the outside of the rotating shaft, and a spoiler blade is provided on the outside of the guide plate.

[0014] As a further optimization solution of the present invention, the spoiler blade includes a blade body, a through hole is formed on the blade body, and spoiler teeth are formed inside the through hole.

[0015] As a further optimization scheme of the present invention, a conductive ring is fixedly provided on the inner side of the central gas pipe air inlet, the conductive ring and electrode 1 are both rotatably connected to the rotating shaft, and conductive rollers are provided between the rotating shaft and the conductive ring and electrode 1.

[0016] The beneficial effects of the present invention are:

[0017] 1) The electrode assembly of the present invention ionizes ammonia, ionizes and cracks ammonia and air in the central gas pipeline to produce free radicals such as NH, NH2, H, O, O3 and various excited substances, which can accelerate the energy exchange between plasma active substances and fuel, accelerate the chemical kinetic process of combustion, stabilize ammonia combustion, and improve combustion temperature and combustion efficiency;

[0018] 2) The microwave generator on the outer periphery of the expanded mouth of the present invention generates microwave discharge which acts on the central flame through the focusing of the antenna, so that the ammonia gas which is difficult to burn completely is fully burned. The microwaves emitted by the microwave generator on the outer periphery of the furnace act evenly on the combustion exhaust gas, reducing the NO generated by incomplete combustion. x emission;

[0019] 3) The present invention forms a central stable combustion zone and a peripheral diffusion combustion zone in the burner outlet area through two-stage air and ammonia grading. The central stable combustion zone adopts fuel-rich combustion to provide a stable stable combustion flame, and the peripheral diffusion combustion zone relies on swirl blades to achieve stable combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the overall structure of a swirl burner according to a first embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of the internal structure of a swirl burner according to a first embodiment of the present invention;

[0022] Figure 3 yes Figure 2 The enlarged view of point A in the middle;

[0023] Figure 4 yes Figure 2 The enlarged view of point B in the middle;

[0024] Figure 5 2 is a schematic diagram of the split structure of the composite gas transmission pipe according to the first embodiment of the present invention;

[0025] Figure 6 is a schematic diagram of the overall structure of a swirl burner according to a second embodiment of the present invention;

[0026] Figure 7 is a schematic diagram of the internal structure of a swirl burner according to a second embodiment of the present invention;

[0027] Figure 8 yes Figure 7 Enlarged view of point C in the middle;

[0028] Fig. 9 2 is a schematic diagram of a composite gas transmission pipe split structure according to a second embodiment of the present invention;

[0029] Fig.10 yes Fig. 9 Enlarged view of point D in the middle.

[0030] In the figure: 1. composite gas transmission pipe; 2. combustion pipe; 3. swirl blade; 4. electrode assembly; 5. guide assembly; 6. microwave generating assembly; 7. drive blade; 8. spoiler blade; 11. peripheral air pipe; 12. peripheral gas pipe; 13. central air pipe; 14. central gas pipe; 21. stable combustion expansion pipe; 22. furnace; 23. waveguide; 31. blade one; 32. blade two; 33. blade three; 34. blade four; 41. electrode one; 42. electrode two; 43. electrode three; 51. positioning column; 52. guide plate; 53. positioning rod; 54. support frame; 55. rotating shaft; 56. conductive ring; 57. conductive roller; 61. microwave antenna one; 62. microwave antenna two; 81. blade body; 82. through hole; 83. spoiler tooth; O. circular ring opening. DETAILED DESCRIPTION

[0031] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0032] First embodiment

[0033] like Figure 1-5As shown, the present embodiment relates to a swirl burner for plasma-assisted combustion for industrial use, including four tube bodies arranged in sequence from the outside to the inside, the four tube bodies are respectively a coaxially arranged peripheral air pipe 11, a peripheral gas pipe 12, a central air pipe 13 and a central gas pipe 14, and the above four tube bodies together constitute a coaxial circular composite gas pipe 1. The composite gas pipe 1 has multiple coaxial annular channels built in, and the annular channels are divided into a peripheral air channel, a peripheral gas channel, a central air channel and a central gas channel. The peripheral air channel is located between the peripheral air pipe 11 and the peripheral gas pipe 12, the peripheral gas channel is located between the peripheral gas pipe 12 and the central air pipe 13, the central air channel is located between the central air pipe 13 and the central gas pipe 14, and the central gas channel is located on the inner side of the central gas pipe 14. The combustion tube 2 is fixedly provided at the exhaust port of the peripheral air pipe 11. The combustion tube 2 includes a bell-shaped stable combustion expansion tube 21 and a furnace 22. The small diameter end of the stable combustion expansion tube 21 is fixedly provided at the exhaust port of the peripheral air pipe 11, and the large diameter end of the stable combustion expansion tube 21 is fixedly provided at the air inlet of the furnace 22. The angle between the expansion port of the stable combustion expansion tube 21 and the axis of the peripheral air pipe 11 is between 30° and 60°. A swirl blade 3 is provided in each annular channel, an electrode assembly 4 is provided inside the composite gas transmission pipe 1, and a guide assembly 5 is provided at its exhaust port. A circular ring opening O is formed between the guide assembly 5 and the central gas channel, and a microwave generating assembly 6 is provided on the outside of the combustion tube 2.

[0034] When the burner is working, the low calorific value gas is burned in a double-stage combustion mode. The low calorific value gas is introduced into the peripheral gas channel and the central gas channel, and air is introduced into the peripheral air channel and the central air channel. The low calorific value gas in the central gas channel is ionized by the electrode assembly 4 to generate plasma. In this embodiment, the low calorific value gas is ammonia. The plasma generated after the ammonia is ionized contains free radicals such as NH2, NH, H, O, O3, and various excited substances, which promote the combustion reaction kinetics process.

[0035] The center of the stable combustion expansion tube 21 is the central stable combustion zone of the central flame, and the outer side of the central stable combustion zone is the diffusion combustion zone of the diffusion flame. Air is fed into the burner through the peripheral air channel and the central air channel respectively. The ammonia fed into the central gas channel generates plasma, and the plasma is mixed and burned with the air fed into the central air channel to form a central flame. The ammonia fed into the peripheral gas channel is mixed with the air fed into the peripheral air channel to form a diffusion flame. Part of the plasma is added to the diffusion combustion zone of the diffusion flame to improve the combustion effect of the diffusion flame. The plasma in the central flame and the diffusion flame is enhanced by the microwave generating component 6 to achieve the purpose of stable combustion of ammonia. The plasma is diffused radially along the annular opening O by the guide component 5, so that the plasma is fully mixed with the air and ammonia.

[0036] Specifically, the flow guide assembly 5 includes a positioning column 51 arranged at the center of the exhaust port of the central gas pipe 14, and a flow guide plate 52 arranged at one end of the positioning column 51. A plurality of blades 1 31 are arranged in the peripheral air channel, and the two ends of the blades 1 31 are respectively fixed on the inner wall of the peripheral air pipe 11 and the outer wall of the peripheral gas pipe 12. A plurality of blades 2 32 are arranged in the peripheral gas channel, and the two ends of the blades 2 32 are respectively fixed on the inner wall of the peripheral gas pipe 12 and the outer wall of the central air pipe 13. A plurality of blades 3 33 are arranged in the central air channel, and the two ends of the blades 3 33 are respectively fixed on the inner wall of the central air pipe 13 and the outer wall of the central gas pipe 14, and the two ends of the blades 4 34 are respectively fixed on the inner wall of the central gas pipe 14 and the outer wall of the positioning column 51. The number of blades 31 of blade one is 12 to 16, and the deflection angle of blade one 31 relative to the axis of the peripheral air pipe 11 is between 30° and 50°. The number of blades 32 of blade two is 12 to 18, and the deflection angle of blade two 32 to the axis of the peripheral gas pipe 12 is between 35° and 50°. The number of blades 33 of blade three is 10 to 16, and the deflection angle of blade three 33 to the axis of the central air pipe 13 is between 30° and 60°. The number of blades 34 of blade four is 10 to 18, and the deflection angle of blade four 34 to the axis of the central gas pipe 14 is between 35° and 60°.

[0037] The guide plate 52 is in an inverted cone shape, and the circular opening O is located between the guide plate 52 and the central gas pipe 14. The electrode assembly 4 includes an electrode 1 41 fixedly arranged at the other end of the positioning column 51, and an electrode 2 42 fixedly arranged on the wall of the central gas pipe 14. Electrode 1 41 is a low-voltage electrode, and electrode 2 42 is a high-voltage electrode. An insulating medium layer is sleeved on the outer side of the high-voltage electrode. The insulating medium layer is made of quartz glass with a thickness of 0.5 mm. The guide assembly 5 also includes a positioning rod 53 that passes through electrode 1 41, and a support frame 54 fixedly arranged on the inner side of the central gas pipe 14. The positioning rod 53 is fixedly arranged between the support frame 54 and the positioning column 51. Electrode 1 41 and the positioning column 51 are fixed to each other. The positioning rod 53 and the positioning column 51 are made of high-temperature resistant and insulating silicon nitride ceramics, and electrode 1 41 is made of stainless steel.

[0038] Furthermore, the electrode assembly 4 also includes an electrode three 43 fixedly arranged on the wall of the central air pipe 13, and the electrode three 43 are all low-voltage electrodes. The air between the central air pipe 13 and the central gas pipe 14 can be ionized through the discharge between the electrode two 42 and the electrode three 43, further increasing the free radicals and various excited substances in the burner, so that the combustion is more complete. The nanosecond pulse power supply provides power support for the high-voltage electrode and the low-voltage electrode, and the output voltage of the nanosecond pulse power supply is 0-32kV, the maximum discharge frequency is 50kHz, and the pulse width is 12ns.

[0039] The microwave generating assembly 6 includes a microwave generator, a microwave antenna 1 61 arranged outside the combustion stabilizing expansion tube 21, and a microwave antenna 2 62 arranged outside the furnace 22. The microwave antenna 1 61 is preferably a parabolic antenna, which can focus the microwave energy on the root of the central flame, with an effective diameter of about several centimeters. The energy generated by the microwave antenna 1 61 makes the central flame burn more stably, thereby achieving the purpose of stabilizing the combustion of ammonia. The microwave antenna 2 62 is used to generate NO generated by the combustion of ammonia in the furnace 22. x The microwave power supply has a microwave frequency of 2.45 GHZ and can provide 0-1000W microwave plasma energy waves.

[0040] The combustion-stabilizing expansion tube 21 is made of a material that is heat-resistant, heat-insulating and microwave-transparent. The angle between the expansion opening of the combustion-stabilizing expansion tube 21 and the axis of the peripheral air tube 11 is between 30° and 60°, and the expansion opening length of the combustion-stabilizing expansion tube 21 is 1 to 3 times the length of the peripheral air tube 11. In addition, waveguides 23 corresponding to the microwave antenna 1 61 and the microwave antenna 2 62 are provided on the side walls of the combustion-stabilizing expansion tube 21 and the furnace 22. The waveguide 23 is made of a material that is heat-resistant, heat-insulating and microwave-transparent. The waveguide 23 is columnar and is arranged perpendicular to the axis of the peripheral air tube 11 to reduce microwave loss.

[0041] Second embodiment

[0042] like Figure 6-10 As shown, this embodiment discloses another swirl burner for plasma-assisted combustion for industrial use. The difference between this burner and the previous embodiment is that the guide assembly 5 is composed of a positioning column 51, a guide vane 52, a rotating shaft 55, a conductive ring 56 and a conductive roller 57. The guide vane 52 of this embodiment is consistent with the previous embodiment. The positioning column 51 is hollow, and the rotating shaft 55 is made of a conductive material. The rotating shaft 55 passes through the electrode 1 41 and the positioning column 51, and one end of the rotating shaft 55 is fixedly arranged at the axis of the guide vane 52. In addition, a driving blade 7 is provided on the outside of the rotating shaft 55, and a spoiler blade 8 is provided on the outside of the guide vane 52. The spoiler blade 8 includes a blade body 81, and a through hole 82 is opened on the blade body 81. A spoiler tooth 83 is provided inside the through hole 82. A conductive ring 56 is fixedly provided on the inner side of the air inlet of the central gas pipe 14. The conductive ring 56 and the electrode 1 41 are both rotatably connected to the rotating shaft 55, and conductive rollers 57 are provided between the rotating shaft 55, the conductive ring 56 and the electrode 1 41. The rotating shaft 55 electrically connects the electrode 2 42 and the conductive ring 56 through the conductive rollers 57, ensuring that the electrode assembly 4 can continuously and stably ionize ammonia.

[0043] After ammonia is introduced into the central gas channel, ammonia drives the rotating shaft 55 to rotate through the driving blade 7, so that the rotating shaft 55 drives the guide vane 52 and the spoiler blade 8 to rotate, and the turbulence and eddy current in the plasma are increased through the spoiler blade 8, so that the plasma is fully mixed with the air and ammonia. The through hole 82 and the spoiler tooth 83 are arranged on the spoiler blade 8, which reduces the weight of the blade body 81, further increases the turbulence and eddy current, and improves the effect of plasma-assisted ammonia combustion.

[0044] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A plasma-assisted combustion swirl burner for industrial use, comprising a coaxial circular composite gas delivery pipe (1) formed by a plurality of tube bodies nested in sequence from outside to inside, and a combustion pipe (2) arranged at the exhaust port of the outermost tube body, characterized in that: The composite gas transmission pipe (1) has a plurality of coaxial annular channels formed inside, each annular channel is provided with a swirl blade (3), the annular channels are used to transport low calorific value fuel gas or combustion-supporting gas, and the innermost annular channel is used to transport low calorific value fuel gas; The composite gas transmission pipe (1) is provided with an electrode assembly (4) inside, and a flow guide assembly (5) is provided at its exhaust port, a circular ring opening is formed between the flow guide assembly (5) and the innermost layer circular channel, the electrode assembly (4) is used to ionize the low calorific value combustion gas in the innermost layer circular channel to generate plasma, the flow guide assembly (5) is used to make the plasma diffuse radially along the circular ring opening, and the combustion pipe (2) is provided with a microwave generating assembly (6) for enhancing the flame.

2. The swirl burner for industrial plasma-assisted combustion according to claim 1, characterized in that: The pipe body is divided into a peripheral air pipe (11), a peripheral gas pipe (12), a central air pipe (13) and a central gas pipe (14) from the outside to the inside.

3. The swirl burner for industrial plasma-assisted combustion according to claim 2, characterized in that: The combustion tube (2) comprises a combustion stabilizing expansion tube (21) and a furnace (22); the small diameter end of the combustion stabilizing expansion tube (21) is fixedly arranged at the exhaust port of the peripheral air tube (11), and the large diameter end of the combustion stabilizing expansion tube (21) is fixedly arranged at the air inlet of the furnace (22); the microwave generating assembly (6) comprises a microwave generator, and a microwave antenna 1 (61) arranged outside the combustion stabilizing expansion tube (21) and a microwave antenna 2 (62) arranged outside the furnace (22).

4. The swirl burner for industrial plasma-assisted combustion according to claim 2, characterized in that: The flow guide assembly (5) comprises a positioning column (51) arranged at the center of the exhaust port of the central gas pipe (14), and a flow guide plate (52) arranged at one end of the positioning column (51); the electrode assembly (4) comprises an electrode 1 (41) arranged at the other end of the positioning column (51), and an electrode 2 (42) arranged on the wall of the central gas pipe (14).

5. The swirl burner for industrial plasma-assisted combustion according to claim 4, characterized in that: The electrode assembly (4) further comprises an electrode three (43) arranged on the wall of the central air pipe (13); the electrode two (42) is a high-voltage electrode, and an insulating medium layer is provided on the outer side of the high-voltage electrode; the electrode one (41) and the electrode three (43) are both low-voltage electrodes.

6. The swirl burner for industrial plasma-assisted combustion according to claim 4, characterized in that: The guide plate (52) is in an inverted cone shape, and the annular opening is located between the guide plate (52) and the central gas pipe (14).

7. The swirl burner for industrial plasma-assisted combustion according to claim 4, characterized in that: The flow guide assembly (5) further comprises a positioning rod (53) penetrating the electrode 1 (41), and a support frame (54) fixedly arranged on the inner side of the central gas pipe (14), wherein the positioning rod (53) is fixedly arranged between the support frame (54) and the positioning column (51).

8. The swirl burner for industrial plasma-assisted combustion according to claim 4, characterized in that: The flow guide assembly (5) further comprises a rotating shaft (55) penetrating the electrode 1 (41) and the positioning column (51); one end of the rotating shaft (55) is fixedly arranged at the axis center of the flow guide plate (52); a driving blade (7) is arranged on the outside of the rotating shaft (55); and a spoiler blade (8) is arranged on the outside of the flow guide plate (52).

9. The swirl burner for industrial plasma-assisted combustion according to claim 8, characterized in that: The spoiler blade (8) comprises a blade body (81), a through hole (82) is provided on the blade body (81), and a spoiler tooth (83) is provided inside the through hole (82).

10. The swirl burner for industrial plasma-assisted combustion according to claim 8, characterized in that: A conductive ring (56) is fixedly provided on the inner side of the air inlet of the central gas pipe (14); the conductive ring (56) and the electrode one (41) are both rotatably connected to the rotating shaft (55); and conductive rollers (57) are provided between the rotating shaft (55), the conductive ring (56) and the electrode one (41).

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