Flue gas internal circulation low-nitrogen burner and boiler

Abstract

The invention provides a flue gas internal circulation low-nitrogen burner which comprises a burner shell, a fire-resistant pouring body and a fuel gas pipe, a center fuel gas pipe and a hot air channel are arranged in the burner shell, the center fuel gas pipe is communicated with a fuel gas supply part, and the hot air channel is communicated with a boiler system air feeder and an air preheater; the fire-resistant pouring body is poured on the inner side wall of the burner shell in the circumferential direction of the burner shell, the fire-resistant pouring body is provided with a flue gas introduction channel and a flue gas injection channel, one end of the flue gas introduction channel is communicated with a flue gas inlet pipeline, the other end of the flue gas introduction channel is communicated with an inlet of the flue gas injection channel, and an outlet of the flue gas injection channel is communicated with a boiler hearth; the number of the peripheral fuel gas branch pipes is n, n is larger than or equal to 30, the peripheral fuel gas branch pipes are arranged on the refractory pouring body, one ends of the peripheral fuel gas branch pipes are communicated with the fuel gas supply part, and the other ends of the peripheral fuel gas branch pipes are communicated with an inlet of the flue gas injection channel. The combustor can reduce generation of NOx in a boiler and reduce harm to the environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of boilers, and in particular relates to a flue gas internal circulation low-nitrogen burner and a boiler. Background Art

[0002] At present, the NOx of gas boilers in self-owned power plants in the steel industry has gradually reached 50mg / m 3 Emissions: NOx for newly built gas boilers is 30mg / m 3 In order to meet the following ultra-low emissions standards, in-furnace denitrification and tail denitrification technologies are usually used. In-furnace combustion denitrification has the advantages of low investment and low operating cost compared to tail flue gas treatment denitrification technology.

[0003] Currently, when denitrification is carried out in the furnace, local high temperatures will occur. High temperature is one of the important conditions for the generation of thermal NOx. Therefore, local high temperatures will cause the oxygen and nitrogen in the combustion zone to react at high temperatures to generate a large amount of NOx. Another important reason for the generation of NOx is the high calorific value of the fuel gas. The high calorific value fuel gas has a high combustion temperature, which will increase the amount of fuel-type NOx generated. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a flue gas internal circulation low nitrogen burner that can effectively reduce the generation of NOx and reduce harm to the environment.

[0005] Another object of the present invention is to provide a boiler.

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

[0007] A flue gas internal circulation low nitrogen burner, comprising:

[0008] A burner housing, wherein a central fuel gas pipe and a hot air passage are provided in the burner housing, wherein the central fuel gas pipe is connected to the fuel gas supply unit, and the hot air passage is connected to the boiler system blower and the air preheater;

[0009] a refractory cast body, cast on the outer side wall of the burner shell along the circumference of the burner shell, the refractory cast body being provided with a flue gas introduction channel and a flue gas ejection channel, one end of the flue gas introduction channel being connected to the flue gas inlet pipeline, the other end being connected to the inlet of the flue gas ejection channel, and the outlet of the flue gas ejection channel being connected to the boiler furnace;

[0010] The surrounding fuel gas branch pipes are n in number, and n≥30. The surrounding fuel gas branch pipes are arranged on the refractory cast body. One end of the surrounding fuel gas branch pipes is connected to the fuel gas supply part, and the other end is connected to the entrance of the smoke duct.

[0011] Optionally, the smoke ejection channel is a Venturi structure.

[0012] Optionally, the calorific value of the fuel gas ejected from the surrounding fuel gas branch pipes is Q 1， Q1≥1500Kcal / Nm 3 The calorific value of the mixture formed after mixing through the flue gas injection channel is Q2, Q2≤800Kcal / Nm 3 .

[0013] Optionally, the air inlet flow direction of the burner housing and the air outlet flow direction of the refractory cast body form an angle of 60°-90°;

[0014] The inner diameter of the refractory cast body is a zooming structure, gradually increasing from an end close to the burner housing to an end far away from the burner housing.

[0015] Optionally, it further includes a swept-back swirl air distributor, the number of blades of the swept-back swirl air distributor is 16 to 24, the swept-back swirl air distributor is fixed to the air outlet end of the central fuel gas pipe, and the swept-back swirl air distributor is arranged on the inner side wall of the refractory cast body;

[0016] A swirl groove is also provided on the inner side wall of the refractory cast body at a position corresponding to the swept-back swirl air distributor, and the central fuel gas pipe can be telescopically moved along its axial direction within the burner shell so that the swept-back swirl air distributor corresponds to the swirl grooves arranged at different positions on the refractory cast body.

[0017] Optionally, the central fuel gas pipe includes a central fuel gas main pipe and a central fuel gas nozzle, the central fuel gas main pipe includes an air inlet end and an air outlet end, and the central fuel gas nozzle is arranged at the air outlet end;

[0018] The central fuel gas nozzle has a conical structure, and its diameter gradually decreases from the end close to the central fuel gas main pipe to the end away from the central fuel gas main pipe. The central fuel gas nozzle is provided with a plurality of injection holes, and the injection holes are distributed in an umbrella shape on the central fuel gas nozzle.

[0019] The central fuel gas main pipe and the central fuel gas nozzle are both made of heat-resistant and corrosion-resistant metal materials.

[0020] Optionally, it further comprises a surrounding air intake main pipe and an air collecting ring pipe, wherein the surrounding air intake main pipe, the air collecting ring pipe and the surrounding fuel gas branch pipes are sequentially connected and are evenly distributed on the refractory cast body along the circumference of the refractory cast body;

[0021] One end of the refractory cast body away from the burner housing is further provided with robust teeth, and the robust teeth are arranged on the inner wall of the refractory cast body along the circumference of the refractory cast body.

[0022] Optionally, the total mass of the mixture of the air flowing out of the hot air channel and the fuel gas ejected from the central fuel gas pipe is M1, and the total mass of the mixture of the fuel gas ejected from the surrounding fuel gas branch pipes and the flue gas is M2, M1=(1.4∼20)×M2.

[0023] The amount of gas ejected from the surrounding fuel gas branch pipes is 50%-75% of the total amount of gas ejected from the central fuel gas pipe and the surrounding fuel gas branch pipes.

[0024] Optionally, also include:

[0025] a central fuel gas support conduit, the central fuel gas support conduit comprising a first end and a second end, the first end being disposed within the fuel burner housing, the second end extending beyond the fuel burner housing, the second end being provided with a fixing member for fixing the central fuel gas pipe;

[0026] an igniter guide tube, one end of which is disposed in the fuel burner housing and the other end of which extends out of the fuel burner housing;

[0027] a flame detector guide tube, one end of which is disposed in the fuel burner housing and the other end of which extends out of the fuel burner housing;

[0028] A low-point sewage pipe, communicating with the gas collecting ring pipe;

[0029] A purge pipe is connected to the gas collecting ring pipe, and the purge pipe is connected to the low-point sewage pipe.

[0030] A boiler, characterized by comprising the flue gas internal circulation low-nitrogen burner as described in any one of the above items.

[0031] It can be seen from the above technical solutions that, compared with the prior art, the flue gas internal circulation low nitrogen burner disclosed in the embodiment of the present invention can reduce the generation of NOx in the boiler and reduce the harm to the environment. Specifically:

[0032] 1) The combustion-supporting air delivered by the boiler system's blower flows through the air preheater at the boiler's tail flue, is preheated, and then enters the refractory cast body through the hot air duct. The fuel gas then enters the refractory cast body through the fuel gas supply unit and the central fuel gas pipe, mixing with the hot air that enters the refractory cast body through the hot air duct to achieve oxygen-rich combustion. The excess air cools the flame at the burner's combustion center, lowering the flame temperature and thus reducing the generation of thermal NOx in the boiler.

[0033] 2) The flue gas in the boiler furnace enters the flue gas ejection channel from the flue gas inlet channel. The fuel gas from the surrounding fuel gas branch pipes 300 is sequentially drawn from the fuel gas supply unit and the surrounding fuel gas branch pipes in a high-speed airflow of 40-150 m / s into the flue gas ejection channel. The flue gas and fuel gas are mixed in the flue gas ejection channel and then ejected. The addition of flue gas can reduce the calorific value per unit volume of the mixed gas, thereby reducing the generation of fuel-type NOx in the boiler.

[0034] 3) The surrounding fuel gas branches divide the fuel into more than 30 small flames. The small flames have a large heat dissipation area and a low flame temperature. The setting of more than 30 surrounding fuel gas branches can increase the flame heat dissipation area, reduce local high temperatures, and inhibit the generation of internal thermal NOx. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0036] Figure 1 This is a schematic structural diagram of a flue gas internal circulation low nitrogen burner disclosed in an embodiment of the present invention;

[0037] Figure 2 This is a front view of the flue gas internal circulation low nitrogen burner disclosed in an embodiment of the present invention;

[0038] Figure 3 This is a partial enlarged view of the structure of the flue gas internal circulation low-nitrogen burner disclosed in an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the arrangement structure of the swept-back swirl air distributor disclosed in an embodiment of the present invention within a refractory cast body;

[0040] Figure 5 This is a schematic structural diagram of the central fuel gas pipe disclosed in an embodiment of the present invention;

[0041] Figure 6 This is a temperature field diagram of the numerical simulation of combustion in a specific embodiment of the present invention.

[0042] Description of reference numerals:

[0043] 100, burner housing; 101, central fuel gas pipe; 1011, central fuel gas main pipe; 1012, central fuel gas nozzle; 1013, injection hole; 102, hot air channel; 103, igniter conduit; 104, flame detector conduit;

[0044] 200, refractory cast body; 201, smoke inlet channel; 202, smoke ejection channel; 203, robust teeth; 204, inner wall of refractory cast body;

[0045] 300, surrounding fuel gas branch pipes;

[0046] 400, all-around intake manifold;

[0047] 500, gas collecting ring pipe;

[0048] 600, swept-back swirl air distributor;

[0049] 700, low point sewage pipe;

[0050] 800, purge pipe;

[0051] 900, boiler water wall tube,

[0052] 1000-Center fuel gas support duct. DETAILED DESCRIPTION

[0053] In view of this, the core of the present invention is to provide a flue gas internal circulation low-nitrogen burner that can effectively reduce the generation of NOx and reduce harm to the environment.

[0054] Another core of the present invention is to provide a boiler.

[0055] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Please refer to Figures 1 to 6 .

[0056] Please refer to Figures 1 to 3The flue gas internal circulation low nitrogen burner disclosed in the embodiment of the present invention includes a burner shell 100, a refractory cast body 200 and a surrounding fuel gas branch pipe 300. Among them, a central fuel gas pipe 101 and a hot air channel 102 are provided in the burner shell 100. The central fuel gas pipe 101 is connected to the fuel gas supply part, and the hot air channel 102 is connected to the boiler system blower and air preheater. The refractory cast body 200 is cast on the inner side wall of the burner shell 100 along the circumference of the burner shell 100. A flue gas introduction channel 201 and a flue gas ejection channel 202 are provided on 200. One end of the flue gas introduction channel 201 is connected to the furnace flue gas, and the other end is connected to the inlet of the flue gas ejection channel 202. The outlet of the flue gas ejection channel 202 is connected to the boiler furnace. The number of surrounding fuel gas branch pipes 30 is n, and n≥30. The surrounding fuel gas branch pipes 300 are provided on the refractory cast body 200. One end of the surrounding fuel gas branch pipes 300 is connected to the fuel gas supply part, and the other end is connected to the inlet of the flue gas ejection channel 202.

[0057] The flue gas internal circulation low nitrogen burner disclosed in the embodiment of the present invention can reduce the generation of NOx in the boiler and reduce the harm to the environment. Specifically:

[0058] 1) The combustion-supporting air delivered by the boiler system's blower flows through the air preheater at the boiler's tail flue, is preheated, and then enters the refractory cast body 200 through the hot air duct 102. The fuel gas then enters the refractory cast body 200 through the fuel gas supply unit and the central fuel gas pipe 101, mixing with the hot air that enters the refractory cast body 200 through the hot air duct 102 to achieve oxygen-rich combustion. The excess air cools the flame at the burner's combustion center, lowering the flame temperature and thus reducing the generation of thermal NOx in the boiler.

[0059] 2) Flue gas in the boiler furnace enters the flue gas ejection channel 202 from the flue gas inlet channel 201. Fuel gas from the surrounding fuel gas branch pipes 300 flows sequentially from the fuel gas supply unit and the surrounding fuel gas branch pipes 300, entraining the flue gas in the boiler furnace into the flue gas ejection channel 202 at a high-speed airflow of 40-150 m / s. The flue gas and fuel gas are mixed in the flue gas ejection channel 202 and then ejected. The addition of flue gas reduces the calorific value per unit volume of the mixed gas, thereby reducing the generation of fuel-type NOx in the boiler.

[0060] 3) The surrounding fuel gas branch pipes divide the fuel into more than 30 small flames. The small flames have a large heat dissipation area and a low flame temperature. The provision of more than 30 surrounding fuel gas branch pipes 300 can increase the flame heat dissipation area, reduce local high temperatures, and inhibit the generation of internal thermal NOx.

[0061] Among them, the flue gas internal circulation low-nitrogen burner disclosed in the embodiment of the present invention uses medium and high calorific value fuels such as natural gas, refinery dry gas, coke oven gas, and raw coal gas, and the temperature of the hot air flowing out of the hot air channel 102 is 120℃-330℃.

[0062] It should be noted that the refractory cast body 200 has the characteristics of fire resistance and heat storage. It can absorb the radiant heat generated by the combustion of fuel gas ejected from the central fuel gas pipe 101 in the burner, establish a constant temperature field in the ignition zone, and ensure that the gas reaches the ignition point.

[0063] The refractory cast body 200 is provided with a boiler water-cooled wall tube 900 , which can absorb the heat of the furnace and reduce the temperature of the contact surface between the refractory cast body 200 and the furnace.

[0064] It should be noted that the hot air channel 102 disclosed in the embodiment of the present invention may be configured with an adjustable damper to adjust the air intake volume.

[0065] To increase injection force, the flue gas ejection channel 202 disclosed in the embodiment of the present invention adopts a Venturi structure. This arrangement utilizes the inherent pressure (≥5 kPa) of the fuel gas branch pipes 300 to convert it into kinetic energy at the outlet of the fuel gas branch pipes 300, generating a high-speed airflow of 40-150 m / s that entrains the mixed flue gas. This simple structure eliminates the need for additional power (such as a fan or compressor) to drive the flue gas mixing.

[0066] It needs to be explained that the Venturi structure is a pipe that first contracts and then gradually expands. By measuring the pressure difference between its inlet cross-section and the minimum cross-section, the flow rate can be calculated using Bernoulli's theorem.

[0067] It should be noted that the calorific value of the fuel gas ejected from the surrounding fuel gas branch pipes 300 is Q 1， Q1≥1500Kcal / Nm 3 The calorific value of the mixture formed after mixing through the flue gas injection channel 202 is Q2, Q2≤800Kcal / Nm 3 The calorific value of the mixture formed by the fuel gas ejected from the surrounding fuel gas branch pipes 300 and mixed in the flue gas injection channel 202 is reduced, and the flame temperature generated by the combustion is low, thereby suppressing the generation of thermal NOx.

[0068] As a further embodiment, the air inlet flow direction of the burner housing 100 disclosed in the embodiment of the present invention and the air outlet flow direction of the refractory cast body 200 form an angle of 60°-90°.

[0069] As a specific embodiment of the present invention, the air inlet flow direction of the burner housing 100 disclosed in the embodiment of the present invention and the air outlet flow direction of the refractory cast body 200 form an angle of 90 degrees.

[0070] As a further embodiment, the refractory cast body 200 disclosed in the embodiment of the present invention has a zooming structure. Specifically, the inner diameter of the refractory cast body 200 gradually increases from the end closest to the burner housing 100 to the end farther from the burner housing 100. This zooming tapered structure eliminates the circumferential uneven distribution caused by the elbow effect after the fluid turns, and even air distribution promotes sufficient combustion and a stable flame.

[0071] Among them, the central gas ignition zone is inside the burner, and the heat storage and heat preservation effect of the cast body can keep a constant temperature field in the ignition zone, ensuring that the gas reaches the ignition point and burns stably without extinguishing the fire.

[0072] As a further embodiment, the flue gas internal circulation low nitrogen burner disclosed in the embodiment of the present invention further includes a swept swirl air distributor 600, wherein the number of blades of the swept swirl air distributor 600 is 16 to 24.

[0073] The swept-back swirl air distributor 600 is fixed to the air outlet end of the central fuel gas pipe 1011, and is arranged on the inner wall 204 of the refractory cast body. With this arrangement, the blades of the swept-back swirl air distributor 600 are away from the fuel gas flow ejected from the fuel gas main pipe, which can prevent the fuel gas from being contaminated by impurities or being burned by high-temperature flames, thereby reducing the failure rate of the burner and extending the service life of the burner.

[0074] As a further example, please refer to Figure 4 A swirl groove is also provided on the inner side wall 204 of the refractory cast body 200 at a position corresponding to the swept-back swirl air distributor 600, and the central fuel gas pipe 101 can be extended and retracted along its axial direction within the burner shell 100, so that the swept-back swirl air distributor 600 corresponds to the swirl grooves arranged at different positions on the refractory cast body 200.

[0075] With such arrangement, the radial dimension R of the swept swirl air distributor 600 can be adjusted by adjusting the position of the central fuel gas pipe 101, and the area ratio corresponding to the distance L between the refractory cast body 200 and the swept swirl air distributor 600 can be changed, so that the amount of air flowing through the swept swirl air distributor 600 and the amount of direct air directly flowing between the swept swirl air distributor 600 and the inner wall of the refractory cast body 200 also change accordingly. By adjusting the air volume of the swept swirl air distributor 600 and the swirl intensity of the total air volume, the central flame can be adjusted, thereby improving the combustion adaptability.

[0076] It should be noted that the air volume of the hot air channel 102 has a coefficient of 2 compared to the air volume required for the central fuel combustion chemical reaction of the burner shell 100, and the excess air coefficient flowing through the swept-back swirl air distributor 600 is 0.8~1.2. The surplus air flows through the annular channel of the refractory cast body 200, wraps the central flame, cools down the flame temperature, reduces the temperature value of the diffusion combustion flame front, and can inhibit the generation of thermal NOx.

[0077] Please refer to Figure 5 The central fuel gas pipe 101 disclosed in the embodiment of the present invention includes a central fuel gas main pipe 1011 and a central fuel gas nozzle 1012. The central fuel gas pipe 1011 includes a gas outlet end and a gas outlet end, and the central fuel gas nozzle 1012 is arranged at the gas outlet end.

[0078] Among them, the central fuel gas nozzle 1012 has a conical structure, and its diameter gradually decreases from the end close to the central fuel gas main pipe 1011 to the end away from the central fuel gas main pipe 1011. A plurality of injection holes 1013 are provided on the central fuel gas nozzle 1012, and the injection holes 1013 are distributed in an umbrella shape on the central fuel gas nozzle 1012.

[0079] The central fuel gas main pipe 1011 and the central fuel gas nozzle 1012 are both made of heat-resistant and corrosion-resistant metal materials.

[0080] With this arrangement, the fuel gas passes through the central fuel gas main pipe 1011 and is ejected from the central fuel gas nozzle 1012, where it mixes with the air passing through the swept swirl air distributor 600 to form oxygen-excess combustion, thereby generating a central flame. The swirling air passing through the swept swirl air distributor 600 and the jet gas ejected from the central fuel gas pipe 101 achieve partial premixed combustion. More than 50% of the excess air can reduce the temperature value of the diffusion combustion flame front and reduce NO X .

[0081] As a further embodiment, the flue gas internal circulation low-nitrogen burner disclosed in the embodiment of the present invention also includes a surrounding air intake main pipe 400 and a gas collecting ring pipe 500, wherein the surrounding air intake main pipe 400, the gas collecting ring pipe 500 and the surrounding fuel gas branch pipes 300 are connected in sequence and are arranged on the refractory cast body 200 along the circumference of the refractory cast body 200.

[0082] Among them, injection ports are provided on the surrounding fuel gas branch pipes 300, and the surrounding fuel gas is ejected at high speed from the injection ports of the surrounding fuel gas branch pipes 300, and is sucked into the smoke injection channel 202 to form a self-circulation.

[0083] In order to adjust the central air intake and the surrounding air intake of the burner, a first regulating valve is further provided in the central fuel gas pipe 101 disclosed in the embodiment of the present invention, and a second regulating valve is further provided in the surrounding fuel gas branch pipes 300.

[0084] As a further embodiment, the refractory cast body 200 disclosed in the embodiment of the present invention is further provided with robust teeth 203 at one end away from the burner housing 100. The robust teeth 203 are arranged on the inner wall of the refractory cast body 200 along the circumference of the refractory cast body 200. This arrangement can form a recirculation zone, thereby preventing the occurrence of flameout.

[0085] As a further example, in the flue gas internal recirculation low-NOx burner disclosed in the embodiment of the present invention, the total mass of the mixture of air flowing out of the hot air passage 102 and fuel gas ejected from the central fuel gas pipe 100 is M1, and the total mass of the mixture of fuel gas ejected from the peripheral fuel gas branch pipes 300 and flue gas is M2, where M1 = (1.4-20) × M2. Because a higher fuel calorific value requires more air for combustion, the central fluid has greater momentum, creating a negative pressure at the boundary. This entrains fuel from the peripheral fuel gas branch pipes 300 to the center, where it mixes with air, providing oxygen for combustion and ensuring complete combustion.

[0086] The amount of gas ejected from the peripheral fuel gas branch pipes 300 is 50%-75% of the total amount of gas ejected from the central fuel gas pipe 101 and the peripheral fuel gas branch pipes 300.

[0087] It should be noted that the flue gas internal circulation low-nitrogen burner disclosed in the embodiment of the present invention also includes a central fuel gas support conduit 1000, wherein the central fuel gas support conduit 1000 includes a first end and a second end, the first end is placed in the fuel burner shell 100, and the second end extends out of the fuel burner shell 100, and the second end is provided with a fixing part for fixing the central fuel gas pipe 101. With such a configuration, the central fuel gas pipe 101 can slide along its axial direction under the guidance of the central fuel gas support conduit 1000. When sliding to a preset position, the central fuel gas pipe 101 can be fixed to the central fuel gas support conduit 1000 by fasteners, wherein the central fuel gas support conduit 1000 is fixed to the burner shell 100.

[0088] The fasteners may preferably be screws.

[0089] The flue gas internal circulation low nitrogen burner disclosed in the embodiment of the present invention also includes an igniter conduit 103, wherein one end of the igniter conduit 103 is placed in the fuel burner shell 100, and the other end extends out of the fuel burner shell 100, so that remote ignition outside the furnace can be achieved to avoid explosion.

[0090] The flue gas internal circulation low-nitrogen burner disclosed in the embodiment of the present invention also includes a flame detector conduit 104, wherein one end of the flame detector conduit 104 is placed in the fuel burner shell 100, and the other end extends out of the fuel burner shell 100, to achieve fire extinguishing protection, automatically close the valve, cut off the fuel, and avoid the accumulation and explosion of gas without open flame in the furnace.

[0091] The flue gas internal circulation low-nitrogen burner disclosed in the embodiment of the present invention also includes a low-point sewage discharge pipe 700 and a purge pipe 800, wherein the low-point sewage discharge pipe 700 is connected to the gas collecting ring pipe 500, and the fuel gas passing through the surrounding fuel gas branch pipes 300 enters the low-point sewage discharge pipe 700 and its speed decreases. Impurities such as water tar in the fuel gas will be precipitated at the low point. Explosion-proof and flame-retardant steam (nitrogen) can be passed through the purge pipe 800, and regular opening and closing can blow impurities into the furnace for combustion, or discharge the sewage to a safe point.

[0092] Please refer to Figure 6 , Figure 6 The calorific value of the fuel gas used is 17556 kJ / Nm 3 The simulated temperature field diagram is a coke oven gas with a temperature of 20°C, a total gas volume of 0.2575 kg / s, a total air excess coefficient of 1.2, a combustion air temperature of 300°C, a 1:1 distribution of the central fuel gas pipe 101 and the surrounding fuel gas branch pipes 300, and 32 surrounding fuel gas branch pipes 300. The simulation result shows that NOx is 27.3 mmg / Nm 3 , far lower than the emission standards of most industries, and even better than the "ultra-low emission" requirements in some regions.

[0093] An embodiment of the present invention further discloses a boiler, comprising the flue gas internal circulation low-nitrogen burner disclosed in any one of the above embodiments.

[0094] Since the boiler adopts the flue gas internal circulation low-nitrogen burner disclosed in the embodiment of the present invention, the boiler disclosed in the embodiment of the present invention has the technical advantages of the flue gas internal circulation low-nitrogen burner disclosed in the above embodiment, and the embodiment of the present invention will not elaborate on this one by one.

[0095] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprises" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0096] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0097] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily 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 is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flue gas internal circulation low nitrogen burner, characterized in that: include: A burner housing, wherein a central fuel gas pipe and a hot air passage are provided in the burner housing, wherein the central fuel gas pipe is connected to the fuel gas supply unit, and the hot air passage is connected to the boiler system blower and the air preheater; a refractory cast body, cast on the inner side wall of the burner shell along the circumference of the burner shell, the refractory cast body being provided with a flue gas introduction channel and a flue gas ejection channel, one end of the flue gas introduction channel being connected to the flue gas inlet pipeline, the other end being connected to the inlet of the flue gas ejection channel, and the outlet of the flue gas ejection channel being connected to the boiler furnace; The surrounding fuel gas branch pipes are n in number, and n≥30. The surrounding fuel gas branch pipes are arranged on the refractory cast body. One end of the surrounding fuel gas branch pipes is connected to the fuel gas supply part, and the other end is connected to the entrance of the smoke duct.

2. The flue gas internal circulation low nitrogen burner according to claim 1 is characterized in that: The smoke ejection channel is a Venturi structure.

3. The flue gas internal circulation low nitrogen burner according to claim 1 is characterized in that: The calorific value of the fuel gas ejected from the surrounding fuel gas branch pipes is Q1, Q1≥1500Kcal / Nm 3 The calorific value of the mixture formed after mixing through the flue gas injection channel is Q2, Q2≤800Kcal / Nm 3 .

4. The flue gas internal circulation low nitrogen burner according to claim 1 is characterized in that: The air inlet flow direction of the burner shell and the air outlet flow direction of the refractory cast body form an angle of 60°-90°; The inner diameter of the refractory cast body is a zooming structure, gradually increasing from an end close to the burner housing to an end far away from the burner housing.

5. The flue gas internal circulation low nitrogen burner according to claim 1, characterized in that: It also includes a swept-back swirl air distributor, the number of blades of the swept-back swirl air distributor is 16 to 24, the swept-back swirl air distributor is fixed to the outlet end of the central fuel gas pipe, and the swept-back swirl air distributor is arranged on the inner side wall of the refractory cast body; A swirl groove is also provided on the inner side wall of the refractory cast body at a position corresponding to the swept-back swirl air distributor, and the central fuel gas pipe can be telescopically moved along its axial direction within the burner shell so that the swept-back swirl air distributor corresponds to the swirl grooves arranged at different positions on the refractory cast body.

6. The flue gas internal circulation low nitrogen burner according to claim 4 is characterized in that: The central fuel gas pipe includes a central fuel gas main pipe and a central fuel gas nozzle, the central fuel gas main pipe includes an air inlet end and an air outlet end, and the central fuel gas nozzle is arranged at the air outlet end; The central fuel gas nozzle has a conical structure, and its diameter gradually decreases from the end close to the central fuel gas main pipe to the end away from the central fuel gas main pipe. The central fuel gas nozzle is provided with a plurality of injection holes, and the injection holes are distributed in an umbrella shape on the central fuel gas nozzle. The central fuel gas main pipe and the central fuel gas nozzle are both made of heat-resistant and corrosion-resistant metal materials.

7. The flue gas internal circulation low nitrogen burner according to claim 1 is characterized in that: It also includes a surrounding air intake main pipe and a gas collecting ring pipe, wherein the surrounding air intake main pipe, the gas collecting ring pipe and the surrounding fuel gas branch pipes are sequentially connected and are evenly distributed on the refractory cast body along the circumference of the refractory cast body; One end of the refractory cast body away from the burner housing is further provided with robust teeth, and the robust teeth are arranged on the inner wall of the refractory cast body along the circumference of the refractory cast body.

8. The flue gas internal circulation low nitrogen burner according to claim 1, characterized in that: The total mass of the mixture of the air flowing out of the hot air channel and the fuel gas ejected from the central fuel gas pipe is M1, and the total mass of the mixture of the fuel gas ejected from the surrounding fuel gas branch pipes and the flue gas is M2, M1=(1.4∼20)×M2; The amount of gas ejected from the surrounding fuel gas branch pipes is 50%-75% of the total amount of gas ejected from the central fuel gas pipe and the surrounding fuel gas branch pipes.

9. The flue gas internal circulation low nitrogen burner according to claim 7, characterized in that: Also includes: a central fuel gas support conduit, the central fuel gas support conduit comprising a first end and a second end, the first end being disposed within the fuel burner housing, the second end extending beyond the fuel burner housing, the second end being provided with a fixing member for fixing the central fuel gas pipe; an igniter guide tube, one end of which is disposed in the fuel burner housing and the other end of which extends out of the fuel burner housing; a flame detector guide tube, one end of which is disposed in the fuel burner housing and the other end of which extends out of the fuel burner housing; A low-point sewage pipe, communicating with the gas collecting ring pipe; A purge pipe is connected to the gas collecting ring pipe, and the purge pipe is connected to the low-point sewage pipe.

10. A boiler, characterized in that: It comprises the flue gas internal circulation low nitrogen burner as described in any one of claims 1 to 9.

Images