Natural gas hydrogen-doped gas burner

Abstract

The invention discloses a natural gas hydrogen-doped gas burner, which adopts a two-stage gas and three-stage air distribution structure, first-stage mixed gas pipes are uniformly arranged on an inner ring in a multi-ring manner, the first-stage mixed gas and first-stage air are subjected to micro-mixing combustion, and second-stage combustion devices are uniformly arranged on the peripheries of the first-stage mixed gas pipes; secondary fuel and secondary air are subjected to diffusive combustion, and a third-stage over fire air channel is arranged on the same ring, so that air classification is enhanced; two-stage fuel gas can be evenly mixed with air through the multi-stage micro-mixing device, multiple strands of evenly-combusted small flames are formed at an outlet of the combustor, ignition and stable combustion of the fuel gas are guaranteed, local high temperature is avoided, air classification is combined, multi-stage combustion is achieved, generation of thermal NOx is reduced, high-power efficient mixed combustion of hydrogen and natural gas can be achieved, and the combustion efficiency is improved. The application range is wide.

Description

Technical Field

[0001] The invention relates to a gas burner, in particular to a gas burner used for natural gas mixed with hydrogen for combustion. Background Art

[0002] As an efficient, zero-carbon clean fuel, hydrogen can be mixed with natural gas to replace traditional carbon-based fuels to reduce carbon; currently, the use of hydrogen and natural gas is mainly small-proportion mixing, and the mixing effect is not ideal. This is because: on the one hand, the combustion characteristics of hydrogen fuel are significantly different from natural gas. It has high reactivity, diffusivity, flame propagation speed and low ignition delay time, which can strongly affect the heat release response and combustion stability of carbon-based flames. The use of existing lean premixing, diffusion and other combustion methods is prone to flashback of hydrogen-mixed fuels and unstable combustion. On the other hand, the adiabatic flame temperature of hydrogen is higher than that of methane, which is easy to cause high thermal NOx emissions, and the local "hot spot" effect caused by uneven fuel mixing can further aggravate NOx generation; in addition, the current hydrogen and natural gas mixing devices such as heat storage combustion, micro-mixed combustion, and full premixed combustion are limited by structural layout, the burner power is small, it is difficult to scale up, and the scope of use is limited. Summary of the invention

[0003] The purpose of the present invention is to provide a natural gas-hydrogen-blended gas burner in view of the above-mentioned deficiencies in the prior art, which can realize uniform mixing of two-stage gas with air through a multi-stage micro-mixing device, forming multiple small flames of uniform combustion at the burner outlet, ensuring the ignition and stable combustion of the gas, avoiding local high temperature and combining with air staging to realize multi-stage combustion and reduce thermal NOx generation, and can realize high-power and efficient mixed combustion of hydrogen and natural gas, with a wide range of applications.

[0004] In order to achieve the above-mentioned purpose, a natural gas hydrogen-blended gas burner of the present invention comprises a primary mixed gas distribution chamber and a secondary air distribution chamber sleeved thereon; the characteristics are as follows: the front end of the primary mixed gas distribution chamber is connected to the primary air distribution chamber, the primary air distribution chamber is provided with a plurality of air inlet holes connected to the secondary air distribution chamber, a radial plate is fixedly provided in the primary air distribution chamber in front of the air inlet hole, and the radial plate is provided with a plurality of air distribution holes; a sealing plate is fixedly provided in the primary mixed gas distribution chamber, the rear ends of a plurality of primary mixed gas pipes arranged and evenly distributed in a multi-ring manner are fixedly connected to the sealing plate and communicate with the primary mixed gas distribution chamber, each primary mixed gas pipe passes through its own air distribution hole and its front end is closed, and the front section of each primary mixed gas pipe is provided with an axially arranged There are at least two rows of small holes with several holes in each row, and the small holes in one row are all connected to a radial guide pipe. The front section of each first-level mixed gas pipe is covered with a first-level air channel, and the first-level air channel is fixedly connected to the radial plate; a second-level gas distribution chamber is arranged outside the second-level air distribution chamber, and the rear ends of several second-level gas pipes distributed in a circle pass through the second-level air distribution chamber and are connected to the second-level gas distribution chamber. The second-level gas pipes are radially located in the second-level air distribution chamber outside the first-level mixed gas distribution chamber, and the front sections of the second-level gas pipes are placed in their respective second-level air channels, and the rear ends of the second-level air channels are communicated with the second-level air distribution chamber; several third-level burnout air channels are arranged between two adjacent second-level air channels, and the rear ends of the third-level burnout air channels are all provided with inlets.

[0005] When the present invention is used, air is introduced into the secondary air distribution chamber, and the primary mixed fuel gas is premixed with hydrogen and natural gas and then introduced into the primary mixed fuel gas distribution chamber and flows into each primary mixed fuel gas pipe, and then passes through a micro-mixing device formed by more than two rows of small holes in each primary mixed fuel gas pipe, and is sprayed into the primary air channel at a high speed, mixed with the primary air formed by part of the air flowing in through the air inlet, and then sprayed out of the nozzle to burn, forming a plurality of small flames; after the secondary fuel gas hydrogen is introduced into the secondary fuel gas distribution chamber, it enters each secondary fuel gas pipe and is sprayed out at the nozzle, and at the same time, part of the air enters each secondary air channel to form secondary air, which is sprayed around each secondary fuel gas pipe and mixed with the secondary fuel gas to burn, thereby realizing multi-stage combustion; the burnout air in each third-stage burnout air channel is supplied by an independent high-pressure fan, and has a higher wind speed than the primary and secondary air, so as to provide the required oxygen for burnout in the later stage of combustion; the present invention Each primary mixed gas pipe and each secondary gas pipe is provided with a primary air channel or a secondary air channel outside to achieve independent air distribution and improve the uniformity of mixing with air. The primary mixed gas is ejected from several small holes of the micro-mixing device, one row of which is connected to the guide pipe. The primary mixed gas ejected from each row of small holes can be more evenly mixed with the primary air on the radial surface, forming multiple small flames of uniform combustion at the burner outlet, ensuring the ignition and stable combustion of the gas, avoiding local high temperature, reducing the generation of thermal NOx, and adding the three-stage burnout air to strengthen air classification and flue gas mixing in the furnace, improving combustion uniformity, and further reducing NOx emissions; the primary mixed gas pipes of the inner circle are evenly arranged in multiple rings, and the secondary air channels and the three-stage burnout air channels of the outer circle are arranged in the same circular ring and at intervals, with a compact structure, which can achieve high-power and high-efficiency mixed combustion and a wide range of applications; As a further improvement of the present invention, a perforated plate is fixedly provided in the primary mixed gas distribution chamber behind the sealing plate, and the perforated plate is provided with a plurality of evenly distributed axial small holes; through the perforated plate, the mixed gas can be rectified and enter each primary mixed gas pipe more evenly, and then be evenly mixed with the primary air; As a further improvement of the present invention, the radial outer end of the guide pipe is adjacent to the inner wall of the outer primary air passage; thus, the mixing area of ​​the primary mixed gas and the primary air on the radial surface can be expanded; As a further improvement of the present invention, the front end of the secondary gas pipe is an outwardly expanding cone with an outward expansion angle of 5-35°; this can increase the reflux and entrainment of the smoke in the furnace, further improving the combustion uniformity; As a further improvement of the present invention, the diameters of the plurality of small holes in each row are all smaller than the critical diameter of hydrogen combustion, thereby preventing hydrogen flashback.

[0006] As a further improvement of the present invention, the plurality of small holes in each row are evenly arranged in the circumferential direction, further improving the uniformity of mixing with the primary air; In summary, the present invention can achieve uniform mixing of two-stage fuel gas with air through a multi-stage micro-mixing device, forming multiple small flames of uniform combustion at the burner outlet, ensuring the ignition and stable combustion of the fuel gas, avoiding local high temperature and combining with air staging to achieve multi-stage combustion and reduce thermal NOx generation, and can achieve high-power and efficient mixed combustion of hydrogen and natural gas, with a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a cross-sectional view of an embodiment of the present invention.

[0008] Figure 2 for Figure 1 End view of the nozzle.

[0009] Figure 3 for Figure 1 Right view of the secondary gas pipes, secondary air channels and tertiary burnout air channels.

[0010] Figure 4 for Figure 1 Enlarged view of point A in .

[0011] Figure 5 for Figure 1 Enlarged view of point B in . DETAILED DESCRIPTION

[0012] The present invention will be further described below in conjunction with the accompanying drawings.

[0013] like Figures 1 to 5As shown, a natural gas hydrogen-blended gas burner of this embodiment comprises a primary mixed gas distribution chamber 1 and a secondary air distribution chamber 2 which is sleeved outside the primary mixed gas distribution chamber; the front end of the primary mixed gas distribution chamber 2 is integrally connected with a primary air distribution chamber 3, the primary air distribution chamber 3 is provided with a plurality of air inlet holes 4 which are connected with the secondary air distribution chamber 2, a radial plate 5 is fixedly provided in the primary air distribution chamber 3 in front of the air inlet holes 4, and the radial plate 5 is provided with a plurality of air distribution holes 6; a sealing plate 7 is welded and fixedly provided in the primary mixed gas distribution chamber 1, and a plurality of air distribution holes 6 are arranged in multiple rings and evenly distributed. The rear end of the primary mixed gas pipe 8 is fixedly connected to the sealing plate 7 and communicated with the primary mixed gas distribution chamber 1. Each primary mixed gas pipe 7 passes through its own air distribution hole 6 and its front end is closed by a cone cover 9. The front section of each primary mixed gas pipe 8 is provided with two rows of axially arranged small holes 10, each row of which has several small holes. The several small holes 10 in each row are evenly arranged in the circumferential direction. The diameter of each small hole 10 is smaller than the critical diameter of hydrogen combustion. The small holes in the rear row are connected with a radial guide pipe 11. The front section of each primary mixed gas pipe 1 is covered with a primary air channel 12. The primary air passages 12 are all fixedly connected to the radial plate 5, and the radial outer end of the guide tube 11 is adjacent to the inner wall of the outer primary air passage 12; a perforated plate 13 is fixedly provided in the primary mixed gas distribution chamber 1 behind the sealing plate 7, and the perforated plate 13 is provided with a number of evenly distributed axial small holes; a secondary gas distribution chamber 16 is provided outside the secondary air distribution chamber 2, and the rear ends of six secondary gas pipes 17 evenly distributed on the circumference pass through the rear end plate of the secondary air distribution chamber 2 and are connected to the secondary gas distribution chamber 16, and the front end 17-1 of the secondary gas pipe 17 is an outwardly expanded cone, and the outward expansion cone angle is The angle is 5-35°, the secondary gas pipes 17 are radially located in the secondary air distribution chamber 2 outside the primary mixed gas distribution chamber 1, the front sections of the secondary gas pipes 17 are placed in their respective secondary air passages 18, and the rear ends of the secondary air passages 18 are communicated with the secondary air distribution chamber 2; a tertiary burnout air passage 19 is provided between two adjacent secondary air passages 18 through a partition 21, and the rear ends of the six tertiary burnout air passages 19 are provided with an inlet 19-1, and each secondary air passage 18 and the tertiary burnout air passage 19 are arranged in the same circular ring and at intervals.

[0014] When the present invention is used, pressurized air is introduced into the secondary air distribution chamber 2, and the primary mixed gas is premixed with hydrogen and natural gas in a certain proportion and then introduced into the primary mixed gas distribution chamber 1, flows into each primary mixed gas pipe 8 after passing through the orifice plate 13, and then passes through the micro-mixing device formed by two rows of several small holes 10 in each primary mixed gas pipe 8, and is sprayed into the primary air channel 12 at a high speed, mixed with the primary air formed by part of the air flowing in through the air inlet 4, and then sprayed out of the nozzle to burn, forming a plurality of small flames; after the secondary gas hydrogen is introduced into the secondary gas distribution chamber 16, it enters each secondary gas pipe 17 and is sprayed out at the nozzle, and at the same time, part of the air enters each secondary air channel 18 to form secondary air, which is sprayed around each secondary gas pipe 17 and mixed with the secondary gas to burn, so that the two-stage gas realizes multi-stage combustion; the burnout air in each third-stage burnout air channel 19 is supplied by an independent high-pressure fan, and has a higher wind speed than the primary and secondary air, so as to provide the required oxygen for burnout in the later stage of combustion; each primary mixed gas pipe 8 and each secondary gas pipe of the present invention are 17 is provided with a primary air channel 12 or a secondary air channel 18 outside to realize independent air distribution of two-stage gas and ensure uniform mixing with air. The primary mixed gas is ejected from several small holes 10 of the micro-mixing device, wherein the rear row of small holes is connected to the guide pipe 11. The primary mixed gas ejected from each row of small holes 10 can be more evenly mixed with the primary air on the radial surface, forming multiple small flames of uniform combustion at the burner outlet, ensuring the ignition and stable combustion of the gas, avoiding local high temperature, reducing the generation of thermal NOx, and adding the three-stage burnout air to strengthen air classification and flue gas mixing in the furnace, improving combustion uniformity, and further reducing NOx emissions; the burner adopts a two-stage gas and three-stage air distribution structure, the primary mixed gas pipes 8 of the inner circle are arranged in multiple rings, and a large number of primary mixed gas pipes 8 can be integrated, and the secondary air channels 18 and the three-stage burnout air channels 19 of the outer circle are arranged in the same circular ring and at intervals, and the structure is compact, which can realize high-power and efficient mixed combustion of hydrogen and natural gas and has a wide range of applications; Through the orifice plate 13, the mixed gas can be rectified and enter each primary mixed gas pipe 8 more evenly. In addition, the radial outer end of the guide pipe 11 is adjacent to the inner wall of the outer primary air channel 12, which can expand the mixing area of ​​the primary mixed gas and the primary air on the radial surface, further improving the uniformity of mixing with the primary air. When the pressure and flow rate of hydrogen are constant, the critical diameter of hydrogen combustion is a constant value; the diameters of the small holes 10 designed under stable working conditions are all smaller than the critical diameter of hydrogen combustion, which can prevent hydrogen flashback; the outward expansion cone at the front end of the secondary fuel gas pipe 17 can increase the reflux and entrainment of the flue gas in the furnace, further improving the combustion uniformity; The above embodiments have been described, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments.

Claims

1. A natural gas hydrogen-blended gas burner, comprising a primary mixed gas distribution chamber and a secondary air distribution chamber enclosed therein; characterized in that: The front end of the first-stage mixed gas distribution chamber is connected to the first-stage air distribution chamber, and the first-stage air distribution chamber is provided with a plurality of air inlet holes connected to the second-stage air distribution chamber. A radial plate is fixedly provided in the first-stage air distribution chamber in front of the air inlet hole, and the radial plate is provided with a plurality of air distribution holes; a sealing plate is fixedly provided in the first-stage mixed gas distribution chamber, and the rear ends of a plurality of first-stage mixed gas pipes arranged and evenly distributed in a multi-ring manner are fixedly connected to the sealing plate and communicate with the first-stage mixed gas distribution chamber, and each first-stage mixed gas pipe passes through its own air distribution hole and has a closed front end, and the front section of each first-stage mixed gas pipe is provided with at least two rows of axially arranged small holes, each row of which has a plurality of small holes, and one row of small holes is connected with a radial guide The front section of each first-level mixed gas pipe is sheathed with a first-level air channel, and the first-level air channels are fixedly connected to the radial plate; a second-level gas distribution chamber is arranged outside the second-level air distribution chamber, and the rear ends of several second-level gas pipes distributed in a circle pass through the second-level air distribution chamber and are connected to the second-level gas distribution chamber, and the second-level gas pipes are radially located in the second-level air distribution chamber outside the first-level mixed gas distribution chamber, and the front sections of the second-level gas pipes are placed in their respective second-level air channels, and the rear ends of the second-level air channels are communicated with the second-level air distribution chamber; several third-level burnout air channels are arranged between two adjacent second-level air channels, and the rear ends of the third-level burnout air channels are provided with inlets.

2. A natural gas hydrogen-blended gas burner as claimed in claim 1, characterized in that: A perforated plate is fixedly arranged in the primary mixed gas distribution chamber behind the sealing plate, and the perforated plate is provided with a plurality of evenly distributed axial small holes.

3. A natural gas hydrogen-blended gas burner as claimed in claim 1 or 2, characterized in that: The radial outer end of the flow guide tube is adjacent to the inner wall of the outer primary air passage.

4. A natural gas hydrogen-blended gas burner according to any one of claims 1 to 3, characterized in that: The front end of the secondary gas pipe is in an outwardly expanding cone shape, and the outward expansion angle is 5-35 degrees.

5. A natural gas hydrogen-blended gas burner as claimed in claim 4, characterized in that: The diameters of the plurality of small holes in each row are all smaller than the critical diameter of hydrogen combustion.

6. A natural gas hydrogen-blended gas burner as claimed in claim 5, characterized in that: The plurality of small holes in each row are evenly arranged in the circumferential direction.

Images