CN218763401U

CN218763401U - Oxidant staged burner

Info

Publication number: CN218763401U
Application number: CN202223275344.2U
Authority: CN
Inventors: 刘奔; 黎佳荣
Original assignee: Hangzhou Zhongtai Hydrogen Energy Technology Co ltd
Current assignee: Hangzhou Zhongtai Hydrogen Energy Technology Co ltd
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-03-28
Anticipated expiration: 2032-12-07

Abstract

The utility model provides an oxidant staged combustion ware, including combustor body and nozzle, the one end tip fixed connection of nozzle and combustor body, the nozzle is inside to have along its length direction extension and mutually independent fuel jet flow passageway, a plurality of first oxidant jet flow channels and a plurality of second oxidant jet flow channel, the internal diameter of first oxidant jet flow channel is greater than second oxidant jet flow channel's internal diameter, a plurality of first oxidant jet flow channels and a plurality of second oxidant jet flow channel's at least one inside reducing portion that is used for changing each oxidant jet flow channel internal diameter that is equipped with, the maximum bore of reducing portion is not more than each oxidant jet flow channel internal diameter. The utility model discloses can improve the incomplete combustion condition of fuel in smelting furnace or industrial kiln stove.

Description

Oxidant staged burner

Technical Field

The utility model relates to a combustor, concretely relates to oxidant staged combustion ware belongs to combustor technical field.

Background

The burner is applied to various industrial scenes, wherein a typical applicable scene is the smelting industry, the fuel is not easy to burn and has low combustion degree due to the characteristics of the fuel and the structure of the burner, and the combustion efficiency is influenced due to incomplete combustion. Especially when various types of fuel are used in furnaces and industrial furnaces for combustion, the incompletely combusted particles carried in the gas stream ejected by the burners may deviate from the gas stream direction under the influence of gravity and affect other parts of the furnace or may be scattered on the surface of the products in the furnace, affecting the quality and yield of the products in the furnace.

Taking petroleum coke powder in particulate solid fuel as an example, the Chinese utility model patent with the application number of 2018207342022 discloses a petroleum coke powder burner and a combustion furnace, which comprise a furnace body and a spray gun assembly; the furnace body is provided with a cavity, the gas transmission part, the desulfurization part, the ignition part and the fuel part are communicated with the cavity through a spray gun assembly, and the fuel part is used for transmitting fuel into the cavity; can remove in the cavity of furnace body through the spray gun subassembly to can adjust the flame position of spray gun subassembly in the cavity inside, adjust through fuel portion and gas transmission portion, can control the flame size of spray gun subassembly in the cavity inside, and can guarantee through desulfurization portion that the gas after the burning carries out desulfurization treatment, the technical effect of clean emission has been guaranteed, the flame size in the burning furnace that has alleviated existence among the prior art is fixed, the unable abundant burning of oil coke powder, entire system combustion efficiency is low, incomplete combustion produces the technical problem of waste residue.

Although the petroleum coke powder burner has the effect of fully burning the petroleum coke powder, the structure is more complex, a plurality of layers of channels are required to be arranged in the burner, the structure of the oxidant supply channel determines that a small amount of oxidant is mixed with the center of the airflow which is sprayed by the burner and carries the solid fuel in particle shape, most of the oxidant is parallel to the periphery of the airflow which is sprayed to form an oxidant layer which is contacted with the periphery of the flame of the burner and is consumed by the periphery part of the flame of the burner, namely, the oxidant at the central part of the flame is less, the oxidant at the periphery part of the flame is more, the burning flame is longer and insufficient, the defect of incomplete burning of the fuel still exists, and the particles which are not completely burnt still have great possibility of scattering into a furnace body.

SUMMERY OF THE UTILITY MODEL

Based on the background, the utility model aims at providing an oxidant staged burner improves the incomplete combustion condition of fuel in smelting furnace or industrial kiln.

In order to realize the purpose of the utility model, the utility model provides a following technical scheme:

an oxidant staging burner comprising:

the combustor comprises a combustor body, a fuel conveying channel and an oxidant conveying channel, wherein the combustor body internally has the fuel conveying channel and the oxidant conveying channel which extend along the length direction of the combustor body and are independent of each other, the fuel conveying channel is used for conveying fuel, and the oxidant conveying channel is used for conveying oxidant and surrounds the outside of the fuel conveying channel; and the number of the first and second groups,

the nozzle is fixedly connected with one end of the burner body, the other end surface of the nozzle, which is opposite to the end connected with the burner body, is configured to be a jet flow surface, a fuel jet flow channel, a plurality of first oxidant jet flow channels and a plurality of second oxidant jet flow channels, which extend along the length direction of the nozzle and are independent from each other, are arranged in the nozzle, the fuel jet flow channel is communicated with the fuel conveying channel, the plurality of first oxidant jet flow channels and the plurality of second oxidant jet flow channels are respectively communicated with the oxidant conveying channel, the inner diameter of each first oxidant jet flow channel is larger than that of each second oxidant jet flow channel, a reducing part used for changing the inner diameter of each oxidant jet flow channel is arranged in at least one of the plurality of first oxidant jet flow channels and the plurality of second oxidant jet flow channels, the maximum caliber of the reducing part is not larger than that of each oxidant jet flow channel, a fuel jet flow outlet, a plurality of first oxidant jet flow outlets and a plurality of second oxidant jet flow outlets are formed in the jet flow channel on the jet flow surface, the fuel jet flow outlet is positioned in the middle of the jet flow surface, and the plurality of second oxidant jet flow outlets and are arranged around the fuel jet flow outlet in an annular array in a mode.

The oxidant staged burner is suitable for various types of fuels, the fuel can be gas fuel, or gasified liquid fuel, or gas-delivered solid particle fuel, specifically, the fuel includes but is not limited to natural gas, coal tar, heavy oil, coal powder, petroleum coke, solid biomass fuel and combustible solid waste, the oxidant is pure oxygen or oxygen-enriched air, wherein the pure oxygen is gas with oxygen concentration more than 99%, the oxygen-enriched air is mixture of oxygen with oxygen concentration more than 21% and less than 99%, the oxidant with initial pressure and flow rate enters the nozzle from the oxidant delivery channel in the burner body, the oxidant with initial pressure and flow rate enters the nozzle through being divided into a plurality of jets which respectively enter a plurality of first oxidant jet channels and a plurality of second oxidant jet channels, because the inner diameter of the first oxidant jet channels is larger than the inner diameter of the second oxidant jet channels, the flow velocity of the oxidant with the same flow velocity in the burner body in the first oxidant jet channel and the second oxidant jet channel is changed by the influence of the inner diameter of the oxidant, oxidant jets with different flow velocities are formed at the first oxidant jet outlet and the second oxidant jet outlet, particularly, the steepness of the flow velocity change curve of the two oxidant jet channels is enhanced due to the change of the inner diameter of each oxidant jet channel by the reducing part arranged in each oxidant jet channel, so that the oxidant jets sprayed by the first oxidant jet outlet and the second oxidant jet outlet have larger difference flow velocity, the adjacent and staggered fast oxidant jets and slow oxidant jets are formed on the jet surface of the nozzle, and the plurality of oxidant jets with different flow velocities effectively impact and permeate the fuel jets positioned at the centers of the plurality of oxidant jets, thereby improving the combustion degree of the fuel at the early stage of the combustion flame, improve the incomplete combustion condition of the fuel in a smelting furnace or an industrial kiln.

Preferably, the diameter-variable part comprises a tapered section, a throat section and a divergent section which are sequentially arranged from the end part of the nozzle connected with the burner body to the jet flow surface direction, the maximum inner diameter of the throat section is not more than the minimum inner diameter of the tapered section and the minimum inner diameter of the divergent section, and the extension length of the throat section is not more than the extension length of the tapered section and the extension length of the divergent section.

The tapered section enables the inner diameter of each oxidant jet flow channel to be gradually reduced on the extension length of the tapered section, the minimum inner diameter part of each oxidant jet flow channel is located in the throat section, the tapered section enables the inner diameter of each oxidant jet flow channel to be gradually increased on the extension length of the tapered section, the flow speed of the oxidant jet flow passing through the tapered section is rapidly changed through the variable diameter part of the structure, and the difference between the flow speeds of the oxidant jet flows injected from the first oxidant jet flow outlet and the second oxidant jet flow outlet is further improved.

Preferably, at least one of the connection part of the throat section and the tapered section and the connection part of the throat section and the tapered section is provided with a transition section with an arc-shaped radial section.

Preferably, the ratio of the maximum internal diameter of the second oxidant jet passage to the maximum internal diameter of the first oxidant jet passage is 1:2 to 5.

The flow rate difference of the oxidant jets with different flow rates generated by the second oxidant jet channel and the first oxidant jet channel within the inner diameter ratio range is more adaptive to the combustion performance of the fuel.

Preferably, the ratio of the smallest inner diameter of the variable diameter portion of the second oxidant jet passage to the smallest inner diameter of the variable diameter portion of the first oxidant jet passage is 1:1 to 3.

The second oxidant jet flow channel variable-diameter part and the first oxidant jet flow channel variable-diameter part within the inner diameter ratio range can generate a more remarkable flow velocity difference of oxidant jet flow, so that different flow rates and different momentum are realized; the oxidant is supplied in a grading way, the first oxidant is firstly mixed with the fuel to assist the ignition and stable combustion of the fuel, and the ratio of the first oxidant to the fuel has the peroxy air coefficient less than 1, so that a fuel-rich atmosphere is formed, and the generation of nitrogen oxides is effectively inhibited; the second oxidant is lengthened through the mixing distance of the high flow rate and the fuel, and the oxidant is continuously supplemented when the reaction of the first oxidant and the fuel is nearly completed, so that the combustion rate can be improved, and although the second oxidant and the fuel form oxygen-rich gas, the fuel is nearly completely reacted at the moment, and no more nitrogen oxides are formed.

Preferably, the ratio of the maximum internal diameter of the first oxidant jet passage to the internal diameter of the fuel jet passage is 1:2 to 5.

Preferably, the number of the first oxidant jet channel and the second oxidant jet channel is at least six, respectively, and the number of the first oxidant jet channel and the second oxidant jet channel is the same.

Preferably, the radial cross-section of the first oxidant jet channel, the radial cross-section of the second oxidant jet channel and the radial cross-section of the fuel jet channel are of the same shape with proportions.

Preferably, the radial cross-section of the first oxidant jet channel, the radial cross-section of the second oxidant jet channel, and the radial cross-section of the fuel jet channel are one of circular, elliptical, and polygonal in shape.

Preferably, each two adjacent first oxidant jet outlets are symmetrically distributed with one second oxidant jet outlet located therebetween as a center, and the distance between each first oxidant jet outlet and its adjacent second oxidant jet outlet is the same.

The plurality of first oxidant jet outlets and the plurality of second oxidant jet outlets form an equidistant annular array distribution, and the plurality of emitted oxidant jets have approximately the same distance, so that the condition that the plurality of oxidant jets interfere with each other in the process of impacting towards the fuel jet is reduced, and the plurality of oxidant jets are converged approximately when impacting with the fuel jet.

Compared with the prior art, the utility model has the advantages of it is following:

the utility model discloses an oxidant staged burner, make the velocity of flow of the oxidant that has initial pressure and velocity of flow in first oxidant efflux passageway and second oxidant efflux passageway influence and change by its inner diameter, form the oxidant efflux of velocity of flow difference at first oxidant efflux mouth and second oxidant efflux export, and because the change of the reducing portion to each oxidant efflux passageway internal diameter that sets up in above-mentioned each oxidant efflux passageway, the oxidant efflux that makes first oxidant efflux mouth and second oxidant efflux export injection presents the great velocity of flow of difference, the effective striking of the oxidant efflux of the different velocity of flow of multistrand permeates the fuel jet that is located stranded oxidant efflux center, thereby improve the combustion degree of fuel in the early stage of burning flame, improve the incomplete combustion condition of fuel in smelting furnace or industrial kiln.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic structural view of an oxidant staged burner of the present invention;

FIG. 2 is a schematic perspective view of a nozzle of the present invention;

fig. 3 is a schematic structural view of the diameter varying section of the present invention.

In the figure: 1. a burner body; 2. a nozzle; 101. a fuel delivery passage; 102. an oxidant delivery channel; 110. an inner tube; 120. an outer tube; 201. a fluidic surface; 202. a fuel jet passage; 203. a first oxidant jet channel; 204. a second oxidant jet passage; 205. a diameter-variable part; 206. a fuel jet outlet; 207. a first oxidant injection outlet; 208. a second oxidant jet outlet; 2051. a tapered section; 2052. a throat section; 2053. a gradual expansion section; 2054. a transition section.

Detailed Description

The technical solution of the present invention is further specifically described below by way of specific embodiments and with reference to the accompanying drawings. It is to be understood that the practice of the present invention is not limited to the following examples, and that any modifications and/or changes in form made to the present invention are intended to fall within the scope of the present invention.

In the utility model, all parts and percentages are weight units, and the adopted equipment, raw materials and the like can be purchased from the market or commonly used in the field if not specified. The methods in the following examples are conventional in the art unless otherwise specified. The components or devices in the following examples are, unless otherwise specified, standard parts or parts known to those skilled in the art, the structure and principle of which are known to those skilled in the art through technical manuals or through routine experimentation.

In the prior art, the structure of the oxidant supply channel inside the burner is used for determining that a small amount of oxidant is mixed with the airflow center of the fuel sprayed by the burner, and most of the oxidant is parallel to the periphery of the airflow sprayed by the burner to form an oxidant layer which is contacted with the periphery of the flame of the burner and is consumed by the flame periphery part of the burner, namely, the oxidant at the flame center part is less, the oxidant at the flame periphery part is more, so that the combustion flame is longer and insufficient, the fuel is not completely combusted, and the incompletely combusted particles are more likely to scatter into a furnace body.

In view of the above technical problem, an embodiment of the present invention discloses an oxidant staged burner, wherein a plurality of first oxidant jet channels 203 and second oxidant jet channels 204 with different inner diameters are arranged at a nozzle 2 of the burner, so that an oxidant with an initial pressure and a flow velocity is divided into a plurality of oxidant jets with two different flow velocities, and the inner diameters of the oxidant jet channels are changed by a variable diameter portion 205 arranged in each oxidant jet channel, so as to enhance the steepness of the flow velocity change curve of the two oxidant jet channels, so that the oxidant jets injected from a first oxidant jet outlet 207 and a second oxidant jet outlet 208 have different flow velocities, and the plurality of oxidant jets with different flow velocities effectively impact and penetrate a fuel jet positioned at the center of the plurality of oxidant jets, thereby improving the combustion degree of the fuel at an early stage of combustion flame, and thus improving the incomplete combustion condition of the fuel in a smelting furnace or an industrial kiln.

In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention.

An oxidant staged burner as shown in fig. 1 comprises a burner body 1 and a nozzle 2, wherein the nozzle 2 is fixedly connected with one end of the burner body 1.

The burner body 1 has a fuel delivery channel 101 and an oxidant delivery channel 102 extending along the length direction thereof and independent from each other for delivering fuel and oxidant, the oxidant delivery channel 102 surrounds the outside of the fuel delivery channel 101, specifically, the burner body 1 is a sleeve type structure having an inner tube 110 and an outer tube 120, the space between the inner tube 110 is configured as the fuel delivery channel 101, and the annular space between the inner tube 110 and the outer tube 120 is configured as the oxidant delivery channel 102. The fuel may be a gas fuel, or a gasified liquid fuel, or a gas-delivered solid particulate fuel, specifically, the fuel includes, but is not limited to, natural gas, coal tar, heavy oil, coal powder, petroleum coke, solid biomass fuel, and combustible solid waste, wherein in this embodiment, the fuel delivered by the fuel delivery channel 101 is a particulate solid fuel, such as petroleum coke, and the oxidant delivered by the oxidant delivery channel 102 may be higher-purity oxygen, or oxygen-enriched air, wherein the pure oxygen is a gas with an oxygen concentration greater than 99%, and the oxygen-enriched air is a mixture of oxygen and air with an oxygen concentration greater than 21% and less than 99%.

As shown in fig. 2, the other end surface of the nozzle 2 opposite to the end connected with the burner body 1 is configured as a jet surface 201, and the nozzle 2 has one fuel jet channel 202, six first oxidant jet channels 203 and six second oxidant jet channels 204 extending along the length direction thereof and independent from each other inside, of course, the number of the first oxidant jet channels 203 and the second oxidant jet channels 204 can be increased according to the actual application requirement, so that the combustion flame of the fuel jet is supplemented with more oxidant.

The fuel jet flow channel 202 is communicated with the fuel conveying channel 101, the six first oxidant jet flow channels 203 and the six second oxidant jet flow channels 204 are respectively communicated with the oxidant conveying channel 102, the radial section of the fuel jet flow channel 202 is circular, the radial section of the first oxidant jet flow channel 203 and the radial section of the second oxidant jet flow channel 204 are both circular, the inner diameter of the first oxidant jet flow channel 203 is larger than that of the second oxidant jet flow channel 204, the inner parts of the first oxidant jet flow channel 203 and the second oxidant jet flow channel 204 are respectively provided with a reducing part 205 for changing the inner diameter of each oxidant jet flow channel, and the maximum caliber of the reducing part 205 is not larger than that of each oxidant jet flow channel. Of course, the radial cross-section of the fuel jet channel 202, the radial cross-section of the first oxidant jet channel 203, and the radial cross-section of the second oxidant jet channel 204 may also be elliptical, or polygonal such as square, hexagonal, etc., as long as the radial cross-section of the first oxidant jet channel 203, the radial cross-section of the second oxidant jet channel 204, and the radial cross-section of the fuel jet channel 202 are guaranteed to be the same shape with a ratio.

One fuel jet channel 202, six first oxidant jet channels 203 and six second oxidant jet channels 204 form one fuel jet outlet 206, six first oxidant jet outlets 207 and six second oxidant jet outlets 208 at the jet surface 201, wherein the fuel jet outlet 206 is located in the middle of the jet surface 201, and the six first oxidant jet outlets 207 and six second oxidant jet outlets 208 are spaced apart and surround the periphery of the fuel jet outlet 206 in an annular array.

Oxidant having an initial pressure and flow rate enters the nozzle 2 from the oxidant delivery passage 102 in the burner body 1, and is divided into a plurality of jets in the nozzle 2 to enter six first oxidant jet passages 203 and six second oxidant jet passages 204, respectively, and since the inner diameter of the first oxidant jet passages 203 is larger than the inner diameter of the second oxidant jet passages 204, the flow rates of the oxidant having the same flow rate in the burner body 1 in the first oxidant jet passages 203 and the second oxidant jet passages 204 are changed by the influence of the inner diameters thereof, and oxidant jets having different flow rates are formed at the first oxidant jet outlets 207 and the second oxidant jet outlets 208.

In particular, due to the change of the inner diameter of each oxidant jet channel by the variable diameter part 205 arranged in each oxidant jet channel, the steepness of the change curve of the flow speed of the two oxidant jet channels is enhanced, the oxidant jets ejected by the first oxidant jet outlet 207 and the second oxidant jet outlet 208 have different flow speeds, the jet surface 201 of the nozzle 2 forms a fast oxidant jet and a slow oxidant jet which are adjacently staggered, and the multiple oxidant jets with different flow speeds effectively impact and penetrate the fuel jets positioned in the centers of the multiple oxidant jets, so that the combustion degree of the particulate solid fuel is improved in the early stage of the combustion flame, and the incomplete combustion condition of the particulate solid fuel in the smelting furnace or the industrial kiln is improved.

In some application scenarios, it is desirable to obtain a plurality of oxidant jets with a greater flow velocity difference, and in order to further improve the difference between the flow velocities of the oxidant jets injected from the first oxidant jet outlet 207 and the second oxidant jet outlet 208, as shown in fig. 3, the variable diameter portion 205 includes a tapered section 2051, a throat section 2052, and a diverging section 2053 which are sequentially arranged from the end of the nozzle 2 connected to the combustor body 1 to the direction of the jet surface 201, the maximum inner diameter of the throat section 2052 is not greater than the minimum inner diameter of the tapered section 2051 and the minimum inner diameter of the diverging section 2053, and the extension length of the throat section 2052 is not greater than the extension length of the tapered section 2051 and the extension length of the diverging section 2053. The tapered section 2051 gradually reduces the inner diameter of each oxidant jet channel over its extended length, the smallest inner diameter portion of each oxidant jet channel is located at the throat section 2052, the tapered section 2053 gradually increases the inner diameter of each oxidant jet channel over its extended length, and the reducing portion 205 of the structure causes the flow rate of the oxidant jet passing through it to change sharply.

In order to change the flow velocity of the oxidant jet in each oxidant jet channel smoothly, transition sections 2054 with arc-shaped radial sections are arranged at the connecting parts of the throat sections 2052 and the tapered sections 2051 and the connecting parts of the throat sections 2052 and the gradually expanding sections 2053.

The ratio of the maximum inner diameter of the second oxidant jet passage 204 to the maximum inner diameter of the first oxidant jet passage 203 is 1: 2-5, the flow rate difference of the oxidant jets with different flow rates generated by the second oxidant jet channel 204 and the first oxidant jet channel 203 within the above inner diameter ratio range is more suitable for the combustion performance of the particulate solid fuel. The ratio of the smallest inner diameter of the variable diameter portion 205 of the second oxidant jet channel 204 to the smallest inner diameter of the variable diameter portion 205 of the first oxidant jet channel 203 is 1: 1-3, the diameter-variable part 205 of the second oxidant jet channel 204 and the diameter-variable part 205 of the first oxidant jet channel 203 within the above-mentioned inner diameter ratio range can generate a more remarkable flow velocity difference of the oxidant jet. The ratio of the maximum inner diameter of the first oxidant jet passage 203 to the inner diameter of the fuel jet passage 202 is 1:2 to 5.

In this embodiment, the maximum inner diameter of the second oxidant jet passage 204 is 3mm, the maximum inner diameter of the first oxidant jet passage 203 is 9mm, and the ratio of the two is 1:3. the minimum inner diameter of the variable diameter portion 205 of the second oxidant jet passage 204 is 1mm, the minimum inner diameter of the variable diameter portion 205 of the first oxidant jet passage 203 is 2mm, and the ratio of the two is 1:2. the ratio of the maximum inner diameter of the first oxidant jet passage 203 to the inner diameter of the fuel jet passage 202 is 1:4. of course, the above ratios can be adjusted according to the actual application requirement, as long as it is ensured to be within the above-defined ratio range.

In the present embodiment, each two adjacent first oxidant jet outlets 207 are symmetrically distributed with one second oxidant jet outlet 208 located therebetween as a center, and the distance between each first oxidant jet outlet 207 and the adjacent second oxidant jet outlet 208 is the same, the six first oxidant jet outlets 207 and the six second oxidant jet outlets 208 form an equidistant annular array distribution, the plurality of emitted oxidant jets have substantially the same distance therebetween, so as to reduce the mutual interference of the plurality of oxidant jets during the impact process towards the fuel jet, and the plurality of oxidant jets are substantially converged when impacting the fuel jet.

The principles and embodiments of the present invention have been explained herein using specific examples, and the above descriptions of the embodiments are only used to help understand the method and its core ideas of the present invention. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.

Claims

1. An oxidant staging burner, characterized by: the oxidant staging burner includes:

the burner body (1) is internally provided with a fuel conveying channel (101) for conveying fuel and an oxidant conveying channel (102) for conveying oxidant, which extend along the length direction of the burner body (1) and are independent from each other, and the oxidant conveying channel (102) surrounds the outside of the fuel conveying channel (101); and (c) a second step of,

a nozzle (2), the nozzle (2) is fixedly connected with one end of the burner body (1), the other end surface of the nozzle (2) opposite to the end connected with the burner body (1) is configured to be a jet surface (201), the nozzle (2) is internally provided with a fuel jet channel (202), a plurality of first oxidant jet channels (203) and a plurality of second oxidant jet channels (204) which extend along the length direction of the nozzle and are independent of each other, the fuel jet channel (202) is communicated with the fuel delivery channel (101), the plurality of first oxidant jet channels (203) and the plurality of second oxidant jet channels (204) are respectively communicated with the oxidant delivery channel (102), the inner diameter of the first oxidant jet channel (203) is larger than that of the second oxidant jet channel (204), at least one of the plurality of first oxidant jet channels (203) and the plurality of second oxidant jet channels (204) is internally provided with a reducing portion (205) for changing the inner diameter of each oxidant jet channel, the maximum diameter of the reducing portion (205) is not larger than that of each oxidant jet channel, the inner diameter of the fuel jet channel (202), the plurality of second oxidant jet channels (203) and the plurality of second oxidant jet channels (204) form a reducing portion (207), and a plurality of second oxidant jet channels (204) which form a reducing portion (207) and a plurality of second oxidant jet outlet of outlet jet channels (206), the fuel jet outlets (206) are positioned in the middle of the jet surface (201), and the plurality of first oxidant jet outlets (207) and the plurality of second oxidant jet outlets (208) are arranged at intervals and surround the periphery of the fuel jet outlets (206) in an annular array mode.

2. An oxidant staging burner as in claim 1, wherein: the variable-diameter part (205) comprises a tapered section (2051), a throat section (2052) and a divergent section (2053) which are sequentially arranged from the end part of the nozzle (2) connected with the combustor body (1) to the direction of the jet flow surface (201), the maximum inner diameter of the throat section (2052) is not more than the minimum inner diameter of the tapered section (2051) and the minimum inner diameter of the divergent section (2053), and the extension length of the throat section (2052) is not more than the extension length of the tapered section (2051) and the extension length of the divergent section (2053).

3. An oxidant staging burner as claimed in claim 2, wherein: at least one of the connection part of the throat section (2052) and the reducing section (2051) and the connection part of the throat section (2052) and the gradually expanding section (2053) is provided with a transition section (2054) with an arc-shaped radial section.

4. An oxidant staging burner as in claim 1, wherein: a ratio of a maximum inner diameter of the second oxidant jet passage (204) to a maximum inner diameter of the first oxidant jet passage (203) is 1:2 to 5.

5. An oxidant staging burner as in claim 1, wherein: the ratio of the minimum inner diameter of the variable diameter portion (205) of the second oxidant jet passage (204) to the minimum inner diameter of the variable diameter portion (205) of the first oxidant jet passage (203) is 1:1 to 3.

6. An oxidant staging burner as in claim 1, wherein: the ratio of the maximum inner diameter of the first oxidant jet passage (203) to the inner diameter of the fuel jet passage (202) is 1:2 to 5.

7. An oxidant staging burner as in claim 1, wherein: the number of the first oxidant jet channels (203) and the second oxidant jet channels (204) is at least six, respectively, and the number of the first oxidant jet channels (203) and the second oxidant jet channels (204) is the same.

8. An oxidant staging burner as in claim 1, wherein: the radial cross-section of the first oxidant jet passage (203), the radial cross-section of the second oxidant jet passage (204), and the radial cross-section of the fuel jet passage (202) are of the same shape with proportions.

9. An oxidant staging burner as claimed in claim 1 or 8, wherein: the radial cross-section of the first oxidant jet passage (203), the radial cross-section of the second oxidant jet passage (204), and the radial cross-section of the fuel jet passage (202) are one of circular, elliptical, and polygonal in shape.

10. An oxidant staging burner as in claim 1, wherein: every two adjacent first oxidant jet outlets (207) are symmetrically distributed with one second oxidant jet outlet (208) located therebetween as a center, and the distance between each first oxidant jet outlet (207) and its adjacent second oxidant jet outlet (208) is the same.