A self-sustaining stable combustion burner with improved inner cavity structure

Abstract

The present invention relates to the technical field of burners, and in particular to a self-sustaining stable combustion burner with an improved inner cavity structure, comprising: a combustion tube, whose outlet end is a flame outlet, and whose inlet end is connected to a plasma generator and a powder inlet; an outer tube, which is sleeved between the outside of the combustion tube and the combustion tube to form a closed return air chamber; the inner cavity structure of the combustion tube is a combustion chamber formed by a reducing neck portion at the inlet end being sequentially connected to a reducing guide portion, a middle cylinder portion, a tempering reducing connection portion, and an outlet end, a tempering guide portion extending along an axial direction is arranged near the top of the inner cavity of the middle cylinder portion, and the combustion tube is provided with a return air duct for connecting the return air chamber and the combustion chamber, the return air duct is located on the tempering reducing connection portion and is located near the top of the middle cylinder portion, and is used to solve the technical problems in the prior art that the continuous operation of the burner needs to rely on a plasma igniter, resulting in low combustion efficiency and easy coking and difficult cleaning of the inner cavity of the combustion chamber.

Description

Technical Field

[0001] The invention relates to the technical field of burners, in particular to a self-sustaining stable combustion burner with an improved inner cavity structure. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] A thermal power plant is a factory that uses pulverized coal as fuel to produce electricity. A burner is a device that sprays pulverized coal fuel and air in a certain way for mixed combustion. Conventional burners use plasma igniters for ignition. During the combustion process, the plasma igniter needs to keep working continuously to ignite the continuously input pulverized coal to ensure the stable operation of the burner. However, the energy consumption of the plasma igniter is relatively large. Not only is the energy consumption high when working for a long time, but the cathode and anode of the plasma igniter are consumables. They have a short service life and a high replacement frequency, resulting in a significant increase in the cost of power generation. If the plasma igniter is replaced, the burner needs to stop and wait, and restarting it will also increase the operating cost of the overall equipment and the maintenance cost is high.

[0004] The prior art discloses an invention patent with the publication number CN116481024A, entitled A forced regenerative cycle self-sustaining burner and a self-sustaining stable combustion control method. The patent discloses that the burner includes an ignition chamber, a self-sustaining chamber, a regenerative channel, a heat extraction unit, an igniter, a coal powder inlet, and a flame outlet. The regenerative channel is provided between the ignition chamber and the self-sustaining chamber, and at least one level of the heat extraction unit is provided inside the regenerative channel. The heat extraction unit is a Rafael tube structure, and a combustion-supporting gas is introduced into the inlet of the heat extraction unit, and the combustion-supporting gas flows to the ignition chamber through the outlet of the heat extraction unit. However, there are still many problems with related technologies including this patented technology: ① The structure is complex, and the production and processing techniques are cumbersome, which is not conducive to reducing costs; ② Easy to coke: Incomplete combustion of coal powder and deposition of coke are prone to occur in the self-sustaining chamber and the ignition chamber, which can easily affect the normal circulation of the coal powder channel for a long time and affect the combustion efficiency; ③ Insufficient heat recovery ratio: The heat extraction unit is small in size and the heat recovery channel is narrow, resulting in insufficient heat recovery ratio, affecting the combustion efficiency and self-sustaining effect of the overall burner. Summary of the invention

[0005] The purpose of the present invention is to provide a self-sustaining stable combustion burner with an improved inner cavity structure, which is used to solve the technical problems in the prior art that the continuous operation of the burner depends on a plasma igniter, resulting in low combustion efficiency and the inner cavity of the combustion chamber is easy to coke and difficult to clean.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A self-sustaining stable combustion burner with an improved inner cavity structure, comprising:

[0008] The combustion tube has a flame outlet at its outlet end and a plasma generator and a powder inlet at its inlet end;

[0009] The outer cylinder is mounted outside the combustion cylinder and forms a closed return air cavity between the combustion cylinder;

[0010] The inner cavity structure of the combustion tube is a combustion chamber formed by connecting the reduced diameter shrinking portion at the inlet end with the middle cylinder portion, the tempering reduced diameter connecting portion, and the outlet end in sequence. A tempering guide portion extending along the axial direction is provided near the top of the inner cavity of the middle cylinder portion. The combustion tube is provided with a return air channel for connecting the return air chamber and the combustion chamber. The return air channel is located on the tempering reduced diameter connecting portion and near the top of the middle cylinder portion. The tempering guide portion is used to form a channel for the return air blown out of the return air channel to flow from the outlet of the middle cylinder portion to the inlet.

[0011] The bottom of the inner cavity structure of the combustion tube is on the same horizontal line, the size of the variable diameter necking part gradually decreases along the powder feeding direction, the size of the variable diameter guide part gradually increases along the powder feeding direction, the size of the middle cylinder part remains unchanged along the axial direction and is larger than the tail end size of the variable diameter necking part, and the size of the tempering variable diameter connecting part gradually decreases along the flame direction.

[0012] Furthermore, the inlet seal of the combustion tube is installed on a support seat, and a powder inlet connected to the combustion chamber of the combustion tube is provided at the bottom of the support seat. The support seat is also provided for one end of the plasma generator bracket to be inserted through, and the other end of the plasma generator bracket is fixed by a support flange, and the support flange is also installed in a seal with the end of the outer tube, and the other end of the outer tube is installed in a seal with the combustion tube through a reducing port.

[0013] Furthermore, a return air chamber is formed between the supporting flange and the outer cylinder, and the return air chamber is connected with the return air cavity through the through hole on the supporting flange.

[0014] Furthermore, a purge cylinder is provided at the bottom of the combustion cylinder, the end of which passes through a supporting flange and is fixedly mounted on the bottom of the inner cavity of the combustion cylinder. A purge tube is slidably mounted in the purge cylinder, and a purge air chamber is provided at the end of the outer cylinder, which is connected to the air inlet of the purge tube.

[0015] Furthermore, the tempering guide portion is formed by the middle cylinder portion being recessed into the inner cavity as an integral part, and the recessed cavity formed by the tempering guide portion being recessed into the inner cavity is in common with the return air cavity.

[0016] Furthermore, the tempering guide portion includes two guide blocks which are symmetrical about the axis and have triangular cross-sections, and the length of the guide blocks along the axis is l The relationship between the length of the middle tube L is: L = 1 ~ 1.5 lThe relationship between the closest distance H between the bottoms of the two guide blocks, the inner diameter D of the middle cylinder, and the distance h between the bottom surface of the guide block and the axis of the middle cylinder is: D=3.4~3.8H, H=2.5~3h, the angle δ of the tempering guide portion recessed to the axis is in the range of: 30°<δ<90°, and the angle θ of the center line of the tempering guide portion recessed to the axis and the horizontal plane is: δ=2θ.

[0017] Furthermore, the inlet size of the reduced-diameter necking portion is larger than the outlet size, and the angle between the straight line where the highest point of the top is located and the horizontal axis is α, 8°<α<15°, the inlet curve consists of a lower semicircle with a radius of D / 2 and an upper semicircle with a radius of R, the center O of the lower semicircle of the inlet curve is coaxial with the axis of the middle cylinder portion, the center O1 of the upper semicircle of the inlet curve is located below the center O of the lower semicircle and the distance between the two is ΔT1, the outlet curve consists of a lower semicircle with a radius of d / 2 and an upper semicircle with a radius of r, the center O2 of the lower semicircle of the outlet curve is coaxial with the central axis of the outlet end of the combustion cylinder, the center O3 of the upper semicircle of the outlet curve is located below the center O2 of the lower semicircle and the distance between the two is ΔT2, ΔT2=1.25ΔT1.

[0018] Furthermore, the inlet size of the variable diameter guide portion is smaller than the outlet size, the inlet of the variable diameter guide portion is connected to the outlet of the variable diameter necking portion, the outlet of the variable diameter guide portion is connected to the inlet of the middle cylinder portion, the lower half of the variable diameter guide portion is coaxial with the lower half of the middle cylinder portion, and the upper half of the variable diameter guide portion is configured as an arc surface that transitions between the outlet of the variable diameter necking portion and the inlet of the middle cylinder portion, and the angle between the cross-section of the arc surface along the vertical direction and the central axis is β, α<β<60°.

[0019] Furthermore, the inlet size of the tempered reducer connection part is larger than the outlet size, and its inlet is connected to the outlet of the middle cylinder part, and the outlet of the tempered reducer connection part is connected to the outlet end. The lower half of the tempered reducer connection part is coaxial with the lower half of the middle cylinder part, and the upper half of the tempered reducer connection part is set as an arc surface that transitions between the outlet of the middle cylinder part and the outlet end of the combustion cylinder, and the angle between the cross section of the arc surface along the vertical direction and the central axis is γ, α<γ<β.

[0020] Furthermore, the outer peripheral wall of the middle cylinder portion is provided with a plurality of heat sinks extending along the axial direction and integrally formed with the wall of the middle cylinder portion.

[0021] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0022] (1) The present invention provides a reducing neck portion, a reducing guide portion and a tempering reducing connection portion at both ends of the middle cylinder portion, so as to achieve the effect that the coal powder entering from the powder inlet enters in a large amount and exits in a small amount along the reducing neck portion, and at the same time changes the jet direction of the coal powder. In combination with the reducing guide portion, a cavity in a negative pressure state appears below the reducing guide portion, and the provision of the tempering reducing connection portion forms resistance to the airflow. At this time, the coordination with the tempering guide portion is more conducive to enhancing the reflux effect, improving the power of the flame circulation in the combustion chamber in the combustion cylinder, and enhancing the self-sustaining stable combustion effect;

[0023] (2) The present invention limits the bottom of the inner cavity structure of the combustion tube to be on the same horizontal line, which is conducive to preventing the coal powder two-phase flow from sinking due to gravity. At the same time, the purge pipe arranged at the bottom of the inner cavity of the combustion tube can improve the negative pressure at the powder inlet to avoid the high pressure at the powder inlet affecting the efficiency of coal powder feeding. Secondly, the negative pressure on the left side of the powder inlet is increased, which is conducive to increasing the negative pressure of the reflux downward and assisting in forming a negative pressure zone. At the same time, it effectively avoids the problem of dead zone coking in the combustion tube due to poor air flow, reduces the impact of shutdown maintenance, and the purge pipe is arranged to be slidably installed along the purge tube, which can effectively and timely remove the coking deposits at the bottom of the inner cavity of the combustion tube;

[0024] (3) The present invention abandons the symmetrical closing design in the traditional technology by providing a tempering reducer and a return air duct provided thereon, and instead adopts an asymmetrical design in which the bottom is flush with the middle cylinder and the top is narrowed. Firstly, it forms resistance to the downstream airflow, which is conducive to assisting the rewinding cycle. Secondly, the return air duct is provided to avoid coking caused by dead zones formed due to poor airflow. At the same time, the return air jet is carried out through the return air duct, thereby simplifying the structure and realizing multiple functions.

[0025] (4) The present invention achieves the purpose of smooth airflow in the combustion tube, less prone to coking, and self-sustaining stable combustion after initial ignition by relying solely on its own circulation flow by limiting the dimensional relationship and angle parameters of various features of the combustion tube inner cavity structure. It simplifies the structure while achieving the effects of strong circulation power, less prone to dead zone formation, and high combustion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the overall cross-sectional view of the present invention;

[0027] Figure 2 It is a cross-sectional schematic diagram of the inner cylinder of the present invention;

[0028] Figure 3 for Figure 2 Middle R view;

[0029] Figure 4 for Figure 2 Schematic diagram of the cross section in the mid-PP direction;

[0030] Figure 5 for Figure 4 Rotated section view in the mid-TT direction;

[0031] Figure 6 for Figure 2 Schematic diagram of the cross section in the mid-VV direction;

[0032] Figure 7 for Figure 2 Middle U view;

[0033] Figure 8 for Figure 2 Schematic diagram of the cross section in the middle WW direction;

[0034] Fig. 9 It is a three-dimensional schematic diagram of the inner cylinder of the present invention from a top-down perspective;

[0035] Fig.10 It is a three-dimensional schematic diagram of the inner cylinder of the present invention when viewed from above;

[0036] Fig.11 It is a schematic diagram of the three-dimensional structure of the variable diameter port of the present invention;

[0037] Fig.12 This is a simulation diagram of the cold state particle field when the present invention does not contain a purge cylinder;

[0038] Fig.13 This is a simulated diagram of the coal powder particle size trajectory field when the present invention does not include a purge cylinder;

[0039] Fig.14 This is a simulation diagram of the cold state particle field when the present invention contains a purge cylinder;

[0040] Fig.15 This is a simulation diagram of the coal powder particle size trajectory field when the present invention contains a purge cylinder.

[0041] In the figure, 100 is an outer cylinder; 101 is a reducing port;

[0042] 200, combustion tube; 201, return air chamber; 202, outlet end; 203, tempering reducing connecting part; 2031, return air duct; 204, middle tube; 2041, tempering guide part; 205, reducing guide part; 206, reducing shrinking part; 207, inlet end;

[0043] 300, support seat;

[0044] 400, plasma generator bracket; 401, powder inlet;

[0045] 500, purge cylinder;

[0046] 600, support flange;

[0047] 700, return air chamber; 701, return air inlet;

[0048] 800. Purge the air chamber; 801. Purge the air inlet. DETAILED DESCRIPTION

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

[0050] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0051] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms "a", "the" and "the" used in the embodiments of the present application and the appended claims are not intended to limit the embodiments of the present application.

[0052] "The" is also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and encompasses any or all possible combinations of one or more of the associated listed items.

[0053] When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0054] In the description of this application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] In addition, in the description of the present application, unless otherwise specified, "plurality" means two or more. "and / or",

[0056] Describing the association relationship of associated objects, it means that there can be three kinds of relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0057] In order to solve the limitations of the prior art, this embodiment provides a technical solution, and the technical solution of the present invention is further described below in conjunction with the drawings and embodiments.

[0058] The present invention is mainly aimed at the common problems of burners in related technologies, such as the need for a plasma igniter to work continuously, high energy consumption and high cost. In addition, although the related technologies disclose structural design of the internal structure of the burner to achieve the effect of self-sustaining circulation, there are still problems such as complex structure, easy deposition and coking, and the need to improve combustion efficiency.

[0059] See attached Figure 1-3, a self-sustaining stable combustion burner with an improved inner cavity structure, comprising: a combustion tube 200, wherein the outlet end 202 is a flame outlet, and the inlet end 207 is connected to the flame outlet of the plasma generator and the powder inlet 401, wherein the plasma generator is used to ignite the coal powder input from the powder inlet 401; an outer tube 100, which is mounted between the outside of the combustion tube 200 and the combustion tube 200 to form a closed return air chamber 201, wherein the purpose of the return air chamber 201 is to input the return air flow into the combustion tube 200 to assist the circulation of part of the flame flow in the inner cavity of the combustion tube 200, so that the plasma igniter can stop working after the initial ignition is stable, thereby achieving the purpose of energy saving and consumption reduction; specifically, the inner cavity structure of the combustion tube 200 is a reduced diameter shrinking portion 207 from the inlet end 207 06 is connected with the reducing guide part 205, the middle cylinder part 204, the tempering reducing connection part 203 and the outlet end 202 in sequence to form a combustion chamber. It can be understood here that after the coal powder enters from the powder inlet 401, it passes through the reducing neck part 206, the middle cylinder part 204 and the tempering reducing connection part 203 in sequence, and the flame is output from the outlet end 202. When flowing in the combustion chamber, part of the flame is sucked upward by the return air blown out by the return air duct 2031 arranged on the tempering reducing connection part 203, so as to realize the reverse flow along the top wall of the middle cylinder part 204 and then rejoin the downstream flame to form a large cycle. The purpose is to save the continuous working energy consumption of the plasma igniter. The circulating flame continuously ignites the coal powder entering from the powder inlet 401 and propels it forward.Specifically, a backfire guide portion 2041 extending along the axial direction is arranged near the top of the inner cavity of the middle cylinder 204, and the combustion cylinder 200 is provided with a return air channel 2031 for connecting the return air chamber 201 and the combustion chamber. Here, the number of the return air channels 2031 is three, and the axis extension lines of the three return air channels 2031 are all located inside the backfire guide portion 2041. The return air channel 2031 is arranged horizontally and is located on the backfire reducer 203 and is located near the top of the middle cylinder 204. The backfire guide portion 2041 is used to form a channel for the return air blown out by the return air channel 2031 to flow from the outlet of the middle cylinder 204 to the inlet. The purpose of the backfire guide portion 2041 here is to form a semi-closed cavity so that the return airflow is less affected by other airflows, but can also allow Heat exchange is generated with the airflow portion below; the bottom of the inner cavity structure of the combustion tube 200 is on the same horizontal line, the size of the reducing neck portion 206 gradually decreases along the powder feeding direction, and the size of the reducing guide portion 205 gradually increases along the powder feeding direction, where the powder feeding direction can be understood as the direction from the inlet to the outlet of the combustion tube 200, the size of the middle cylinder portion 204 remains unchanged along the axial direction and is larger than the tail end size of the reducing neck portion 206, the size of the tempering reducing connection portion 203 gradually decreases along the flame direction, where the flame direction can be understood as the direction from the inlet to the outlet of the combustion tube 200, and the size relationship of each part is limited here, the main purpose is to design the inner cavity structure of the combustion tube 200 to achieve the guidance and assistance of the airflow, so as to better achieve the purpose of internal airflow circulation and reduce the deposition and coking in dead zones.

[0060] See attached Figure 1 and attached Figure 9-11The inlet sealing installation support seat 300 of the combustion tube 200 is fixedly installed on the bottom of the inner wall of the outer tube 100. The bottom of the support seat 300 is provided with a powder inlet 401 connected to the combustion chamber of the combustion tube 200. It can be understood that the powder inlet 401 passes through the outer tube 100 and is connected to the external coal powder raw material bin. In addition, the powder inlet 401 is also connected to the inner cavity of the combustion tube 200. The support seat 300 is also provided for one end of the plasma generator bracket 400 to be inserted through. The other end of the plasma generator bracket 400 is fixed by a support flange 600. The support flange 600 is also sealed and installed with the end of the outer tube 100. The other end of the outer tube 100 is sealed and installed with the combustion tube 200 through a reducing port 101. The shape of the reducing port 101 is designed to match the tempering reducing connection 203, and at the same time, it is beneficial to help the return air flow enter the return air duct 2031. A return air chamber 700 is formed between the support flange 600 and the outer tube 100. The return air chamber 700 is connected to the return air cavity 201 through the through hole on the support flange 600. The return air chamber 700 is equipped with a return air inlet 701. A purge cylinder 500 is also provided at the bottom of the combustion tube 200. The end of the purge cylinder 500 passes through the support flange 600 and is fixedly installed at the bottom of the inner cavity of the combustion tube 200. The outlet of the purge cylinder 500 is located above the powder inlet 401. A purge pipe is slidably installed in the purge cylinder 500. A purge air chamber 800 is provided at the end of the outer tube 100. The purge air chamber 800 is equipped with a purge air inlet 801. The purge air chamber 800 is connected to the air inlet of the purge pipe. The purge pipe can be moved and is mainly used to purge the coal powder deposited at the bottom of the inner cavity of the combustion tube 200 to prevent it from coking. In addition, the outer wall of the middle cylinder portion 204 is provided with a plurality of heat sinks extending along the axial direction and integrally formed with the wall of the middle cylinder portion 204. The provision of the heat sinks here is beneficial to protecting the service life of the combustion cylinder 200 and preventing the internal combustion temperature from being too high and affecting its structural stability.

[0061] See attached Figure 2-5 The tempering guide 2041 is formed by the middle cylinder 204 being recessed into the inner cavity, and the recessed cavity formed by the tempering guide 2041 is common to the return air cavity 201. The purpose here is the same as that of the heat sink, which is used to dissipate heat from the combustion cylinder 200 in a timely manner. The tempering guide 2041 includes two guide blocks that are symmetrical about the axis and have triangular cross-sections. It should be noted that the tail end of the guide block is close to the outlet of the middle cylinder 204, and the length of the guide block along the axis is l The relationship between the length L of the middle tube 204 is: L = 1 to 1.5 lThe purpose of the length design here is to reserve turning space for the circulating flow of the flame airflow. The relationship between the closest distance H between the bottoms of the two guide blocks, the inner diameter D of the middle cylinder 204, and the distance h between the bottom surface of the guide block and the axis of the middle cylinder 204 is: D=3.4~3.8H, H=2.5~3h, the angle δ of the tempering guide 2041 recessed to the axis is in the range of: 30°<δ<90°, preferably δ=60°, the angle θ between the center line of the angle of the tempering guide 2041 recessed to the axis and the horizontal plane is: δ=2θ, preferably θ=30°, in addition, when the tempering guide 2041 is recessed inwardly along the axial direction, an inclined surface transition is adopted with the outer wall of the middle cylinder 204, the angle between the inclined surface near the inlet side of the middle cylinder 204 and the horizontal plane is λ, the angle between the inclined surface near the outlet side of the middle cylinder 204 and the horizontal plane is ζ, 15°<λ<ζ<60°, preferably λ=30°, ζ=45°.

[0062] See attached Figure 2 , Figure 7 and Figure 8 The inlet size of the reduced-diameter necking portion 206 is larger than the outlet size, the angle between the straight line where the highest point of the top is located and the horizontal axis is α, 8°<α<15°, preferably α=10°, the inlet curve is composed of a lower semicircle with a radius of D / 2 and an upper semicircle with a radius of R, the center O of the lower semicircle of the inlet curve is coaxial with the axis of the middle cylinder 204, the center O1 of the upper semicircle of the inlet curve is located below the center O of the lower semicircle and the distance between the two is ΔT1, the outlet curve is composed of a lower semicircle with a radius of d / 2 and an upper semicircle with a radius of r, and the lower semicircle of the outlet curve is The center O2 is coaxial with the central axis of the outlet end 202 of the combustion tube 200, and the center O3 of the upper semicircle of the outlet curve is located below the center O2 of the lower semicircle and the distance between the two is ΔT2, ΔT2=1.25ΔT1. It can be understood that D is the inner cavity diameter of the middle cylinder part 204, d is the inner cavity diameter of the outlet end 202 of the combustion tube 200, the inlet curve and the outlet curve refer to the contour curves at the inlet and outlet of the variable diameter necking part 206 respectively, and the center O1 of the upper semicircle of the inlet curve is located above the center O2 of the lower semicircle of the outlet curve.

[0063] See attached Figure 2 , Fig. 9 and Fig.10The inlet size of the reducing guide part 205 is smaller than the outlet size, the inlet of the reducing guide part 205 is connected to the outlet of the reducing necking part 206, the outlet of the reducing guide part 205 is connected to the inlet of the middle cylinder part 204, the lower half of the reducing guide part 205 is coaxial with the lower half of the middle cylinder part 204, the upper half of the reducing guide part 205 is arranged as an arc surface transitioning between the outlet of the reducing necking part 206 and the inlet of the middle cylinder part 204, the angle between the cross section of the arc surface along the vertical direction and the central axis is β, α<β<60°, it can be understood here that, in the vertical plane, β is the angle between the contour line of the top of the reducing guide part 205 and the horizontal central axis.

[0064] See attached Figure 2 The inlet size of the tempered reducer 203 is larger than the outlet size, and its inlet is connected to the outlet of the middle cylinder 204, and the outlet of the tempered reducer 203 is connected to the outlet end 202. The lower half of the tempered reducer 203 is coaxial with the lower half of the middle cylinder 204, and the upper half of the tempered reducer 203 is set as an arc surface that transitions between the outlet of the middle cylinder 204 and the outlet end 202 of the combustion cylinder 200. The angle between the cross-section of the arc surface in the vertical direction and the central axis is γ, α<γ<β. It can be understood here that γ is the angle between the contour line of the top of the tempered reducer 203 and the horizontal central axis.

[0065] When the burner of the present invention is working, refer to the attached Figure 1 , the coal powder enters the combustion tube 200 from the air inlet through the support seat 300, the plasma igniter works, ignites the coal powder, and the flame is pushed forward along the combustion tube 200. When passing through the reducing neck portion 206, the direction of the flame is changed to a downward and forward jet. At this time, negative pressure is formed at the top of the reducing guide portion 205, and then enters the middle cylinder portion 204. When it runs to the tempering reducing connection portion 203, the return air is blown out through the return air duct 2031. At the same time, the inclined surface of the tempering reducing connection portion 203 forms a certain resistance to the flame airflow, and the two together form a return negative pressure. The negative pressure sucks part of the flame upward and then moves in the opposite direction along the tempering guide portion 2041. When it runs to the reducing guide portion 205, the flame airflow joins the mainstream flame downward to form a large cycle. After stabilization, the plasma igniter can be turned off, and the continuously input coal powder is continuously ignited by the circulating flame to form a stable self-sustaining combustion state. At the same time, the purge air introduced through the purge pipe can purge the coal powder deposited at the bottom of the inner cavity of the combustion tube 200 to prevent coking.

[0066] See attached Figure 12-15 , using Fluent software for calculation simulation, in the structure disclosed by the present invention, a stable and smooth cycle without dead zones can be formed in the combustion chamber, thereby achieving a state of self-sustaining combustion.

[0067] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-sustaining stable combustion burner with improved inner cavity structure, characterized in that: include: A combustion tube (200), wherein the outlet end (202) is a flame outlet, and the inlet end (207) is connected to a plasma generator and a powder inlet (401); An outer cylinder (100) is mounted on the outside of the combustion cylinder (200) and forms a closed return air chamber (201) between the combustion cylinder (200); The inner cavity structure of the combustion tube (200) is a combustion chamber formed by connecting the reduced diameter necking portion (206) at the inlet end (207) with the reduced diameter guide portion (205), the middle tube portion (204), the tempering reduced diameter connection portion (203), and the outlet end (202) in sequence; a tempering guide portion (2041) extending along the axial direction is provided near the top of the inner cavity of the middle tube portion (204); the combustion tube (200) is provided with a return air duct (2031) for connecting the return air chamber (201) and the combustion chamber; the return air duct (2031) is located on the tempering reduced diameter connection portion (203) and near the top of the middle tube portion (204); the tempering guide portion (2041) is used to form a channel for the return air blown out of the return air duct (2031) to flow from the outlet of the middle tube portion (204) to the inlet; The bottom of the inner cavity structure of the combustion tube (200) is on the same horizontal line, the size of the reducing neck portion (206) gradually decreases along the powder feeding direction, the size of the reducing guide portion (205) gradually increases along the powder feeding direction, the size of the middle tube portion (204) remains unchanged along the axial direction and is larger than the tail end size of the reducing neck portion (206), and the size of the tempering reducing connection portion (203) gradually decreases along the flame direction.

2. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 1, characterized in that: The inlet of the combustion cylinder (200) is sealed and installed on a support seat (300). The bottom of the support seat (300) is provided with a powder inlet (401) which is connected to the combustion chamber of the combustion cylinder (200). The support seat (300) is also provided for one end of the plasma generator bracket (400) to be inserted through. The other end of the plasma generator bracket (400) is fixed by a support flange (600). The support flange (600) is also sealed and installed with the end of the outer cylinder (100). The other end of the outer cylinder (100) is sealed and installed with the combustion cylinder (200) through a reducing port (101).

3. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 2, characterized in that: A return air chamber (700) is formed between the support flange (600) and the outer cylinder (100), and the return air chamber (700) is connected to the return air cavity (201) through a through hole on the support flange (600).

4. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 2 or 3, characterized in that: A purge cylinder (500) is also provided at the bottom of the combustion cylinder (200), the end of the purge cylinder (500) passes through the support flange (600) and is fixedly mounted on the bottom of the inner cavity of the combustion cylinder (200), a purge pipe is slidably mounted in the purge cylinder (500), and a purge air chamber (800) is provided at the end of the outer cylinder (100), the purge air chamber (800) being connected to an air inlet of the purge pipe.

5. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 4, characterized in that: The tempering guide portion (2041) is formed by the middle cylinder portion (204) being recessed into the inner cavity as a whole, and the recessed cavity formed by the tempering guide portion (2041) being recessed into the inner cavity is in common with the return air cavity (201).

6. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 5, characterized in that: The tempering guide portion (2041) comprises two guide blocks which are symmetrical about the axis and both have triangular cross-sections, and the length of the guide blocks along the axis is l The relationship between the length L of the middle tube (204) is: L = 1 to 1.5 l The relationship between the closest distance H between the bottoms of the two guide blocks, the inner diameter D of the middle cylinder (204), and the distance h between the bottom surface of the guide block and the axis of the middle cylinder (204) is: D=3.4~3.8H, H=2.5~3h, the range of the angle δ of the tempering guide (2041) recessed toward the axis is: 30°<δ<90°, and the size of the angle θ between the center line of the angle of the tempering guide (2041) recessed toward the axis and the horizontal plane is: δ=2θ.

7. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 6, characterized in that: The inlet size of the reduced-diameter necking portion (206) is larger than the outlet size, the angle between the straight line where the highest point of the top is located and the horizontal axis is α, 8°<α<15°, the inlet curve is composed of a lower semicircle with a radius of D / 2 and an upper semicircle with a radius of R, the center O of the lower semicircle of the inlet curve is coaxial with the axis of the middle cylinder (204), the center O1 of the upper semicircle of the inlet curve is located below the center O of the lower semicircle, and the distance between the two is ΔT1, the outlet curve is composed of a lower semicircle with a radius of d / 2 and an upper semicircle with a radius of r, the center O2 of the lower semicircle of the outlet curve is coaxial with the central axis of the outlet end (202) of the combustion cylinder (200), the center O3 of the upper semicircle of the outlet curve is located below the center O2 of the lower semicircle, and the distance between the two is ΔT2, ΔT2=1.25ΔT1.

8. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 7, characterized in that: The inlet size of the reducing guide part (205) is smaller than the outlet size; the inlet of the reducing guide part (205) is connected to the outlet of the reducing necking part (206); the outlet of the reducing guide part (205) is connected to the inlet of the middle cylinder part (204); the lower half of the reducing guide part (205) is coaxial with the lower half of the middle cylinder part (204); the upper half of the reducing guide part (205) is arranged as an arc surface transitioning between the outlet of the reducing necking part (206) and the inlet of the middle cylinder part (204); the included angle between the cross section of the arc surface along the vertical direction and the central axis is β, α<β<60°.

9. A self-sustaining stable combustion burner with improved inner cavity structure according to claim 8, characterized in that: The inlet size of the tempered reducer connection part (203) is larger than the outlet size, the inlet is connected to the outlet of the middle cylinder part (204), the outlet of the tempered reducer connection part (203) is connected to the outlet end (202), the lower half of the tempered reducer connection part (203) is coaxial with the lower half of the middle cylinder part (204), the upper half of the tempered reducer connection part (203) is arranged as an arc surface transitioning between the outlet of the middle cylinder part (204) and the outlet end (202) of the combustion cylinder (200), the angle between the cross section of the arc surface along the vertical direction and the central axis is γ, α<γ<β.

10. The self-sustaining stable combustion burner with improved inner cavity structure according to claim 5, characterized in that: The outer peripheral wall of the middle cylinder portion (204) is provided with a plurality of heat sinks extending along the axial direction and integrally formed with the wall of the middle cylinder portion (204).

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