Gas-assisted pulverized coal preheating type dual-fuel burner

Abstract

The invention provides a fuel gas auxiliary pulverized coal preheating type dual-fuel burner, and belongs to the field of burning equipment.The burner comprises a burner body and a pre-burner assembly, a fuel gas channel used for conveying biomass fuel gas is arranged in a fuel gas pipeline, and a pre-burner assembly is arranged in the pre-burner assembly. A primary air channel for mixing pulverized coal and air is defined and formed between the primary air mixing pipeline and the outer afterburning air pipeline, and a secondary air channel is defined and formed between the outer peripheral wall of the primary air mixing pipeline and the inner peripheral wall of the secondary air pipeline. The invention aims to realize combustion of biomass gasified gas and pulverized coal in the same combustor, so that the biomass gas can assist preheating and pre-combustion of the pulverized coal, and stable combustion of the combustor under low load can be realized; and a traditional oil feeding stable combustion mode can be replaced, pollutant emission is reduced, and meanwhile the fuel oil cost of a power plant is reduced.

Description

Technical Field

[0001] The invention relates to the field of combustion equipment, and in particular to a gas-assisted pulverized coal preheating type dual-fuel burner. Background Art

[0002] In the era of flexible peak-shaving of coal-fired power, the power plant pulverized coal boilers mixed with agricultural and forestry biomass coupling power generation is an important transitional means for my country's current thermal power transformation. Using biomass to replace part of the coal, helping thermal power generation to de-coalize, peak-shaving, and reduce emissions has become a hot research direction. In addition, with the surge in the amount of new energy grid-connected power generation, the demand for deep peak-shaving of coal-fired power plants has deepened, requiring thermal power units to operate at low loads.

[0003] Since the combustion characteristics of biomass gasification gas and coal are very different, in the existing biomass gasification indirect coupled coal-fired unit power generation system, the biomass gasification gas is burned in the furnace burnout zone through an independent gas burner, and is not directly burned with coal powder in the main combustion zone of the furnace; in addition, the coal powder burner in the existing technology has weak self-stabilizing combustion ability under low load, and it is difficult to keep up with the demand for deep peak regulation. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a gas-assisted pulverized coal preheating dual-fuel burner, which can make the biomass gasification gas and pulverized coal burn synergistically in the same burner, so that the biomass gas can assist the pulverized coal in preheating and precombustion, and can achieve stable combustion of the burner under low load, meeting the needs of deep peak regulation.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solutions: A gas-assisted pulverized coal preheating dual-fuel burner, comprising: a burner body and a pre-burner assembly;

[0006] The pre-combustion chamber assembly comprises: a gas pipeline, an inner combustion air pipeline, an outer supplementary combustion air pipeline, a pre-combustion chamber body, an outer sleeve, and an oxygen supply pipe;

[0007] The gas pipeline is provided with a gas channel for conveying biomass gas, and a nozzle is provided at the front end of the gas channel; the inner combustion-supporting air duct is sleeved on the outer circumference of the gas pipeline, and a combustion-supporting air injection channel is defined between the inner circumferential wall of the inner combustion-supporting air duct and the outer circumferential wall of the gas pipeline; the outer supplementary combustion air duct is sleeved on the outer circumference of the inner combustion-supporting air duct, and a supplementary combustion air delivery channel is defined between the inner circumferential wall of the outer supplementary combustion air duct and the outer circumferential wall of the inner combustion-supporting air duct; the rear end of the pre-combustion chamber body is connected to the front end of the outer supplementary combustion air duct, and a pre-combustion chamber is opened in the pre-combustion chamber body, and the pre-combustion chamber is respectively connected to the gas pipeline and the inner combustion-supporting air duct; the outer sleeve is sleeved on the outer circumference of the pre-combustion chamber body, and a coal powder collection reflux channel is defined between the inner circumferential wall of the outer sleeve and the outer circumferential wall of the pre-combustion chamber body; the oxygen supply pipe is inserted into the supplementary combustion air delivery channel from back to front;

[0008] The burner body includes a primary air mixing duct and a secondary air duct, the external supplemental combustion air duct is inserted into the primary air mixing duct from back to front, and the nozzle is located in the primary air mixing duct, and the front end of the primary air mixing duct protrudes from the front end of the outer sleeve, the pre-combustion chamber is connected to the primary air mixing duct, and a primary air channel of mixed pulverized coal and air is defined between the primary air mixing duct and the external supplemental combustion air duct, the secondary air duct is sleeved on the outer periphery of the primary air mixing duct, and a secondary air channel is defined between the outer peripheral wall of the primary air mixing duct and the inner peripheral wall of the secondary air duct.

[0009] Preferably, an annular guide edge extending radially inward is provided along the front end of the outer sleeve, and the inner diameter of the guide edge is smaller than the inner diameter of the front end of the pre-combustion chamber body; and / or

[0010] A first axial cyclone is provided in the coal powder collecting and reflux channel.

[0011] Preferably, a plurality of leakage holes are evenly distributed circumferentially on the guide edge.

[0012] Preferably, the leakage holes are arranged obliquely, and the leakage holes gradually approach the central axis of the pre-combustion chamber from back to front.

[0013] Preferably, a rectifier is provided on the inner peripheral wall of the primary air mixing duct, and the rectifier is located at the rear end of the outer sleeve.

[0014] Preferably, one or more concentrating rings are provided in the primary air mixing duct, and the concentrating rings are arranged at intervals at the front end of the outer sleeve, and a flow channel is provided inside the concentrating ring that runs through the front and rear end surfaces thereof, and the inner diameter of the flow channel gradually decreases and then gradually increases from the back to the front. When a plurality of the concentrating rings are provided, the plurality of the concentrating rings are arranged relative to each other in sequence from the back to the front, and in any two adjacent concentrating rings, the rear end inner diameter of the flow channel of the concentrating ring located on the front side is larger than the front end inner diameter of the flow channel of the concentrating ring located on the rear side.

[0015] Preferably, the front end of the primary air mixing duct is a combustion port, and combustion stabilizing teeth are provided along the circumference of the combustion port.

[0016] Preferably, a conical expansion hole is provided along the front end of the internal combustion-supporting air duct, the inner diameter of which gradually increases from the back to the front.

[0017] Preferably, a second axial swirler is provided in the supplementary combustion air delivery channel.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The biomass gasification gas and pulverized coal are burned in the same burner in a coordinated manner, so that the biomass gas can assist the pulverized coal in preheating and pre-combustion, and can achieve stable combustion of the burner under low load; it is conducive to replacing the traditional oil-added stable combustion method, reducing pollutant emissions, and reducing the fuel costs of power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a gas-assisted pulverized coal preheating dual-fuel burner;

[0021] Figure 2 Schematic diagram of the guide structure.

[0022] In the figure:

[0023] 1. Burner body;

[0024] 11. Primary air mixing duct; 111. Primary air channel; 112. Rectifier; 113. Concentrator ring; 114. Burner port; 115. Combustion stabilizing tooth;

[0025] 12. Secondary air duct; 121. Secondary air duct;

[0026] 2. Pre-burner assembly;

[0027] 21. gas pipeline; 211. gas channel; 212. nozzle;

[0028] 22. Internal combustion air duct; 221. Combustion air injection channel; 222. Conical expansion hole;

[0029] 23. External afterburning air duct; 231. Afterburning air delivery channel; 232. Second axial swirler;

[0030] 24. Pre-combustion chamber body; 241. Pre-combustion chamber;

[0031] 25, outer sleeve; 251, coal powder collection and return channel; 252, guide edge; 2521, leakage hole; 253, first axial cyclone;

[0032] 26. Oxygen supply tube. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0035] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a replaceable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0036] Combination Figure 1-2As shown, a burner comprises: a burner body 1 and a pre-combustion assembly 2; the pre-combustion assembly 2 comprises: a gas pipeline 21, an inner combustion air pipeline 22, an outer supplementary combustion air pipeline 23, a pre-combustion chamber body 24, an outer sleeve 25, and an oxygen supply pipe 26; the gas pipeline 21 has a gas channel 211 for conveying biomass gas, and a nozzle 212 is provided at the front end of the gas channel 211; the inner combustion air pipeline 22 is sleeved on the outer periphery of the gas pipeline 21, and the inner peripheral wall of the inner combustion air pipeline 22 is connected to the gas pipeline 21. The outer peripheral wall of the pre-combustion chamber body 24 is defined to form a combustion air introduction channel 221; the outer afterburner air duct 23 is sleeved on the outer periphery of the inner combustion air duct 22, and a afterburner air delivery channel 231 is defined to be formed between the inner peripheral wall of the outer afterburner air duct 23 and the outer peripheral wall of the inner combustion air duct 22; the rear end of the pre-combustion chamber body 24 is connected to the front end of the outer afterburner air duct 23, and a pre-combustion chamber 241 is opened in the pre-combustion chamber body 24, and the pre-combustion chamber 241 is respectively connected to the gas pipeline 21 and the inner combustion air duct 22. The outer sleeve 25 is sleeved on the outer periphery of the pre-combustion chamber body 24, and a coal powder collection reflux channel 251 is defined between the inner peripheral wall of the outer sleeve 25 and the outer peripheral wall of the pre-combustion chamber body 24; the oxygen supply pipe 26 is inserted into the supplementary combustion air delivery channel 231 from back to front; the burner body 1 includes a primary air mixing pipe 11 and a secondary air pipe 12, the outer supplementary combustion air pipe 23 is inserted into the primary air mixing pipe 11 from back to front, and the nozzle 212 is located in the primary air mixing pipe 11. The primary air mixing duct 11 is arranged in the combined duct 11, and the front end of the primary air mixing duct 11 protrudes from the front end of the outer sleeve 25, the pre-combustion chamber 241 is connected to the primary air mixing duct 11, and a primary air channel 111 of mixed pulverized coal and air is defined between the primary air mixing duct 11 and the external supplementary combustion air duct 23, the secondary air duct 12 is sleeved on the outer periphery of the primary air mixing duct 11, and a secondary air channel 121 is defined between the inner circumferential wall of the primary air mixing duct 11 and the outer circumferential wall of the secondary air duct 12.

[0037] Biomass gas and combustion-supporting air are ejected through the nozzle 212, and after a certain degree of turbulence and mixing, they are ignited inside the pre-combustion chamber 241. The supplementary combustion air also enters the pre-combustion chamber 241 to realize graded air supply. The oxygen supply pipe 26 supplements pure oxygen and has an oxygen-enriching function, which is conducive to the formation of a high-temperature, high-oxygen stable combustion environment inside the pre-combustion chamber 241 for biomass gas, which has a low calorific value. Part of the pulverized coal and air mixture from the boiler pulverized coal pipeline directly enters the primary air channel 111; part of it enters the primary air channel 111 and then enters the pulverized coal collection and reflux channel 251. After coming out of the pulverized coal collection and reflux channel 251, part of it directly enters the primary air channel 111, and another part enters the pre-combustion chamber 241. After being preheated and pre-combusted at the rear end of the stable gas flame, it rushes out of the pre-combustion chamber 241 with the flame and re-enters the primary air channel 111, creating better combustion conditions for subsequent pulverized coal and reducing the difficulty of stable combustion of the burner under low load. Exemplarily, the secondary air duct 12 includes an inner secondary air duct and an outer secondary air duct, and correspondingly, the secondary air channel 121 is divided into an inner secondary air channel and an outer secondary air channel, and an inner secondary air cyclone and an outer secondary air tangential damper are respectively provided in the secondary air channel 121. Finally, all the pulverized coal and air mixture, flame and flue gas enter the main combustion zone of the boiler through the front end of the mixing channel, and at the same time, a stable annular recirculation zone is formed at the front end of the mixing channel in conjunction with the swirl inner secondary air and the swirl outer secondary air. The annular recirculation zone can continuously entrain the high-temperature flue gas in the mixing channel to provide flame and heat for the unburned and unburned pulverized coal, and finally a stable combustion zone is formed at the front end of the mixing channel to achieve flame stabilization under low load.

[0038] In some embodiments, an annular guide edge 252 extending radially inward is provided along the front end of the outer sleeve 25, and the inner diameter of the guide edge 252 is smaller than the inner diameter of the front end of the pre-combustion chamber body 24; and / or.

[0039] A first axial cyclone 253 is provided in the pulverized coal collection and reflux channel 251 .

[0040] Part of the coal powder and air mixture coming out of the coal powder collection and return channel 251 directly enters the primary air channel 111, and part of it deflects the flow direction and sprays back into the pre-combustion chamber 241. Among them, the setting of the guide edge 252 is conducive to ensuring the reflux of coal powder and the reverse spraying of coal powder into the interior of the pre-combustion chamber. Exemplarily, the first axial swirler 253 is a small-angle axial swirler. In this embodiment, the angle is selected to be 30° axially deflected, which serves to moderately reduce the axial velocity of the concentrated coal powder airflow mixture; and serves as a fixed support for the fixed outer sleeve 25 and the pre-combustion chamber body 24.

[0041] like Figure 2As shown, in some embodiments, the guide edge 252 is evenly distributed with a plurality of leakage holes 2521 in the circumferential direction, which is conducive to realizing that a small portion of the coal powder and air mixture coming out of the coal powder collection return channel 251 enters the primary air channel 111 through the leakage holes 2521.

[0042] In some embodiments, the leakage holes 2521 are arranged obliquely, and the leakage holes 2521 gradually approach the central axis of the pre-combustion chamber 241 from the back to the front. A small portion of the coal powder and air mixture coming out of the coal powder collection and return channel 251 passes through the leakage holes 2521 and enters the primary air channel 111 toward the central axis of the pre-combustion chamber 241, which is beneficial to reducing the jet pressure of the coal powder and air mixture in the annular guide 252, and better realizing the thick and thin separation of the coal powder and air mixture.

[0043] In some embodiments, a rectifier 112 is provided on the inner wall of the primary air mixing duct 11, and the rectifier 112 is located at the rear end of the outer sleeve 25. When the pulverized coal and air mixture from the boiler pulverized coal pipeline enters the primary air channel 111, it tends to concentrate toward the center, which is conducive to ensuring that part of the concentrated pulverized coal enters the pulverized coal collection and reflux channel 251.

[0044] In some embodiments, one or more concentrating rings 113 are provided in the primary air mixing duct 11, and the concentrating rings 113 are arranged at intervals at the front end of the outer sleeve 25. A flow channel is provided inside the concentrating ring 113 that runs through the front and rear end surfaces thereof, and the inner diameter of the flow channel gradually decreases and then increases from the back to the front. When a plurality of the concentrating rings 113 are provided, the plurality of the concentrating rings 113 are arranged relative to each other in sequence from the back to the front, and in any two adjacent concentrating rings 113, the rear end inner diameter of the flow channel of the concentrating ring 113 located on the front side is larger than the front end inner diameter of the flow channel of the concentrating ring 113 located on the rear side.

[0045] Exemplarily, three concentrating rings 113 are provided in the primary air mixing duct 11, and the frontmost concentrating ring 113 is fixed to the inner peripheral wall of the primary air mixing duct 11. The pre-combusted pulverized coal and flame rush out of the pre-combustion chamber 241 and re-enter the primary air channel 111, and are successively mixed with the pulverized coal and air mixture concentrated by the three concentrating rings 113, so that the pulverized coal and air mixture that has not entered the pre-combustion chamber 241 in the primary air mixing duct 11 is preheated and pre-combusted step by step, which is conducive to the pulverized coal and air mixture being easier to ignite and reducing the difficulty of stable combustion of the burner under low load.

[0046] In some embodiments, the front end of the primary air mixing duct 11 is a burner port 114, and a flame stabilizing tooth 115 is provided along the circumference of the burner port 114. Finally, all the coal powder and air mixture, flame and flue gas are ejected from the burner port 114 through the flame stabilizing tooth 115 and enter the main combustion area of ​​the boiler. The flame stabilizing tooth 115 has a certain turbulence and concentration effect, which is conducive to forming a stable combustion area outside the burner port 114 and achieving flame stabilization under low load.

[0047] In some embodiments, a conical expansion hole 222 with an inner diameter gradually increasing from the back to the front is provided along the front end of the inner combustion air duct 22. The conical expansion hole 222 plays a guiding role, strengthens the injection effect of the supplementary combustion air on the biomass gas and the combustion air, and is conducive to purging and preheating the inner wall of the pre-combustion chamber body 24.

[0048] In some embodiments, a second axial swirler 232 is provided in the supplementary combustion air delivery channel 231. The supplementary combustion air forms a certain degree of swirling flow before entering the pre-combustion chamber 241, which is conducive to achieving graded air supply together with the combustion-supporting air.

[0049] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A gas-assisted pulverized coal preheating dual-fuel burner, characterized in that: include: Burner body and pre-burner assembly; The pre-combustion chamber assembly comprises: a gas pipeline, an inner combustion air pipeline, an outer supplementary combustion air pipeline, a pre-combustion chamber body, an outer sleeve, and an oxygen supply pipe; The gas pipeline is provided with a gas channel for conveying biomass gas, and a nozzle is provided at the front end of the gas channel; the inner combustion-supporting air duct is sleeved on the outer circumference of the gas pipeline, and a combustion-supporting air injection channel is defined between the inner circumferential wall of the inner combustion-supporting air duct and the outer circumferential wall of the gas pipeline; the outer supplementary combustion air duct is sleeved on the outer circumference of the inner combustion-supporting air duct, and a supplementary combustion air delivery channel is defined between the inner circumferential wall of the outer supplementary combustion air duct and the outer circumferential wall of the inner combustion-supporting air duct; the rear end of the pre-combustion chamber body is connected to the front end of the outer supplementary combustion air duct, and a pre-combustion chamber is opened in the pre-combustion chamber body, and the pre-combustion chamber is respectively connected to the gas pipeline and the inner combustion-supporting air duct; the outer sleeve is sleeved on the outer circumference of the pre-combustion chamber body, and a coal powder collection reflux channel is defined between the inner circumferential wall of the outer sleeve and the outer circumferential wall of the pre-combustion chamber body; the oxygen supply pipe is inserted into the supplementary combustion air delivery channel from back to front; The burner body includes a primary air mixing duct and a secondary air duct, the external supplemental combustion air duct is inserted into the primary air mixing duct from back to front, and the nozzle is located in the primary air mixing duct, and the front end of the primary air mixing duct protrudes from the front end of the outer sleeve, the pre-combustion chamber is connected to the primary air mixing duct, and a primary air channel of mixed pulverized coal and air is defined between the primary air mixing duct and the external supplemental combustion air duct, the secondary air duct is sleeved on the outer periphery of the primary air mixing duct, and a secondary air channel is defined between the outer peripheral wall of the primary air mixing duct and the inner peripheral wall of the secondary air duct.

2. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 1 is characterized in that: An annular guide edge extending radially inward is provided along the front end of the outer sleeve, and the inner diameter of the guide edge is smaller than the inner diameter of the front end of the pre-combustion chamber body; and / or A first axial cyclone is provided in the coal powder collecting and reflux channel.

3. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 2 is characterized in that: A plurality of leakage holes are evenly distributed circumferentially on the guide edge.

4. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 3 is characterized in that: The leakage holes are arranged obliquely, and the leakage holes gradually approach the central axis of the pre-combustion chamber from the back to the front.

5. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 1 is characterized in that: A rectifier is provided on the inner peripheral wall of the primary air mixing duct, and the rectifier is located at the rear end of the outer sleeve.

6. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 1 is characterized in that: One or more concentrating rings are arranged in the primary air mixing duct, and the concentrating rings are arranged at intervals at the front end of the outer sleeve. A flow channel is arranged inside the concentrating ring to pass through the front and rear end surfaces thereof, and the inner diameter of the flow channel gradually decreases and then gradually increases from the back to the front. When a plurality of concentrating rings are provided, the plurality of concentrating rings are arranged relative to each other in sequence from the back to the front, and in any two adjacent concentrating rings, the rear end inner diameter of the flow channel of the concentrating ring located on the front side is larger than the front end inner diameter of the flow channel of the concentrating ring located on the rear side.

7. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 1 is characterized in that: The front end of the primary air mixing duct is a combustion port, and combustion stabilizing teeth are arranged along the circumference of the combustion port.

8. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 1, characterized in that: A conical expansion hole with an inner diameter gradually increasing from the back to the front is arranged along the front end of the internal combustion-supporting air duct.

9. The gas-assisted pulverized coal preheating dual-fuel burner according to claim 1, characterized in that: A second axial swirler is provided in the supplementary combustion air delivery channel.

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