A hydrogen-doped natural gas burner

Abstract

The application discloses a natural gas hydrogen-mixed gas burner, which adopts a two-stage gas and three-stage air distribution structure, a plurality of annular first-stage mixed gas pipes are uniformly arranged in an inner ring, micro-mixed combustion is carried out between the first-stage mixed gas and first-stage air, a second-stage combustion device is uniformly arranged around the first-stage mixed gas pipe, diffusion combustion is carried out between the second-stage fuel and second-stage air, a third-stage combustion air passage is arranged in the same ring to strengthen air staging, the two-stage gas is uniformly mixed with air through a plurality of micro-mixed devices, a plurality of small flames with uniform combustion are formed at the outlet of the burner, ignition and stable combustion of the gas are ensured, local high temperature is avoided, air staging is combined, multi-stage combustion is realized, the generation of thermal NOx is reduced, hydrogen and natural gas can be mixed and combusted at high power and high efficiency, and the application range is wide.

Description

TECHNICAL FIELD

[0001] The present application relates to a gas burner, in particular to a gas burner for mixed combustion of natural gas and hydrogen. BACKGROUND

[0002] As a clean fuel with high efficiency and zero carbon, hydrogen can be mixed with natural gas for combustion instead of traditional carbon-based fuels to reduce carbon emissions. Currently, the main use of hydrogen and natural gas mixed combustion is small-scale 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 those of natural gas, with 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. Using existing lean premixed, diffusion and other combustion methods can cause hydrogen fuel backfire, unstable combustion and other problems; on the other hand, the adiabatic flame temperature of hydrogen is higher than that of methane, which can lead to high thermal NOx emissions, and the local "hot spot" effect caused by uneven mixing of fuel can further exacerbate NOx generation; in addition, current hydrogen and natural gas mixed combustion devices such as regenerative combustion, micro-mixed combustion and full premixed combustion are limited by structural arrangement, and the burner power is small, making it difficult to be large-scale and limiting its use. SUMMARY

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

[0004] In order to achieve the above object, the natural gas hydrogen mixed gas burner comprises a primary mixed gas distribution chamber and a secondary air distribution chamber sleeved outside the primary mixed gas distribution chamber; the primary mixed gas distribution chamber is connected with a primary air distribution chamber at the front end; the primary air distribution chamber is provided with a plurality of air inlet holes communicating with the secondary air distribution chamber; a radial plate is fixedly arranged in the primary air distribution chamber in front of the air inlet holes, and the radial plate is provided with a plurality of air distribution holes; a sealing plate is fixedly arranged in the primary mixed gas distribution chamber; the rear ends of a plurality of primary mixed gas pipes arranged in multiple rings and uniformly distributed are fixedly connected with the sealing plate and communicate with the primary mixed gas distribution chamber; each primary mixed gas pipe passes through the air distribution hole and is closed at the front end; the front section of each primary mixed gas pipe is provided with at least two rows of axial small holes; one row of small holes is connected with a radial flow guide pipe; the front section of each primary mixed gas pipe is sleeved with a primary air passage; the primary air passage is fixedly connected with the radial plate; a secondary gas distribution chamber is arranged outside the secondary air distribution chamber; the rear ends of a plurality of secondary gas pipes distributed in the circumference pass through the secondary air distribution chamber and are connected with the secondary gas distribution chamber; the secondary gas pipes are arranged in the secondary air distribution chamber outside the primary mixed gas distribution chamber in the radial direction; the front sections of the secondary gas pipes are arranged in the secondary air passages; the rear ends of the secondary air passages communicate with the secondary air distribution chamber; a plurality of tertiary overfire air passages are arranged between the adjacent secondary air passages; and the rear ends of the tertiary overfire air passages are provided with inlets.

[0005] When the present application is used, the secondary air distribution chamber is connected with air, the primary mixed gas is connected with the primary mixed gas distribution chamber after premixing hydrogen and natural gas, flows into each primary mixed gas pipe, and is injected into the primary air passage at high speed through the micro-mixing device formed by two or more rows of small holes in each primary mixed gas pipe, mixed with the primary air formed by the air flowing through the air inlet, and then is injected out of the nozzle to burn and form multiple small flames; the secondary gas hydrogen is injected into the secondary gas distribution chamber, flows into each secondary gas pipe, and is injected out of the nozzle, while part of the air flows into each secondary air passage to form the secondary air around each secondary gas pipe to mix and burn with the secondary gas, so that multi-stage combustion is realized; the tertiary air in each tertiary air passage is supplied by an independent high-pressure fan, has higher air speed compared with the primary and secondary air, and provides the oxygen required for the combustion in the later stage; the primary air passage or the secondary air passage is arranged outside each primary mixed gas pipe and each secondary gas pipe, independent air supply is realized, the uniformity of the air mixing is improved, the primary mixed gas is injected out of the small holes of the micro-mixing device, one row of small holes is connected with the flow guide pipe, the primary mixed gas injected out of each row of small holes can be more uniformly mixed with the primary air on the radial plane, multiple small flames with uniform combustion are formed at the outlet of the burner, the ignition and stable combustion of the gas are ensured, local high temperature can be avoided, the generation of thermal NOx is reduced, the air staging and the mixing of the flue gas in the furnace are strengthened by the tertiary air, the combustion uniformity is improved, and the NOx emission is further reduced; the primary mixed gas pipes in the inner ring are arranged in multiple rings, the secondary air passages and the tertiary air passages in the outer ring are arranged in the same circle and are spaced apart, the structure is compact, high-power and efficient mixed combustion can be realized, and the application range is wide.

[0006] As a further improvement of the present application, a perforated plate is fixed in the primary mixed gas distribution chamber behind the sealing plate, and the perforated plate is provided with multiple uniformly distributed axial small holes; through the perforated plate, the mixed gas can be straightened and more uniformly enter each primary mixed gas pipe to be uniformly mixed with the primary air.

[0007] As a further improvement of the present application, the radial outer end of the flow guide pipe is adjacent to the inner wall of the outer primary air passage; the mixing area of the primary mixed gas and the primary air on the radial plane can be expanded.

[0008] As a further improvement of the present application, the front end of the secondary gas pipe is outwardly tapered, and the outward expansion angle is 5-35°; the backflow and entrainment of the flue gas in the furnace can be increased, and the combustion uniformity can be further improved.

[0009] As a further improvement of the present application, the diameter of each row of small holes is smaller than the critical diameter of hydrogen combustion; the hydrogen backfire can be prevented.

[0010] As a further improvement of the present application, each row of small holes is uniformly arranged in the circumferential direction; the uniformity of the mixing with the primary air is further improved.

[0011] In summary, the present application can realize two-stage gas mixing with air uniformly through multi-stage micro-mixing device, forming multiple small flames of uniform combustion at the outlet of the burner, ensuring the ignition and stable combustion of the gas, avoiding the occurrence of local high temperature, and combining with air staging, realizing multi-stage combustion, reducing the generation of thermal NOx, and realizing high-power and efficient mixing combustion of hydrogen and natural gas, with wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a sectional view of an embodiment of the present application.

[0013] Figure 2 is a sectional view of an embodiment of the present application. Figure 1 is a sectional view of an embodiment of the present application.

[0014] Figure 3 is a sectional view of an embodiment of the present application. Figure 1 is a sectional view of an embodiment of the present application.

[0015] Figure 4 is a sectional view of an embodiment of the present application. Figure 1 is an enlarged view of A in the sectional view of an embodiment of the present application.

[0016] Figure 5 is an enlarged view of B in the sectional view of an embodiment of the present application. Figure 1 is an enlarged view of B in the sectional view of an embodiment of the present application. DETAILED DESCRIPTION

[0017] The present application will be further described below in conjunction with the drawings.

[0018] As shown in the drawings, the present application is a multi-stage micro-mixing device for mixing hydrogen and natural gas, which comprises a mixing device body, a hydrogen inlet, a natural gas inlet, a first air inlet, a second air inlet, a third air inlet, a hydrogen outlet, a natural gas outlet, and a combustion chamber. Figures 1 to 5As shown, the hydrogen-doped natural gas burner of the embodiment comprises a first mixed gas distribution chamber 1, a second air distribution chamber 2 sleeved outside the first mixed gas distribution chamber; the front end of the first mixed gas distribution chamber 1 is integrally connected with a first air distribution chamber 3, the first air distribution chamber 3 is provided with a plurality of air inlet holes 4 communicating with the second air distribution chamber 2, a radial plate 5 is fixedly arranged in the front part of the first air distribution chamber 3, and the radial plate 5 is provided with a plurality of air distribution holes 6; a sealing plate 7 is fixedly arranged in the first mixed gas distribution chamber 1, the rear ends of a plurality of first mixed gas pipes 8 arranged in a plurality of rings and uniformly distributed are fixedly connected with the sealing plate 7 and communicate with the first mixed gas distribution chamber 1, the front ends of the first mixed gas pipes 8 are closed by a conical cover 9, the front part of each first mixed gas pipe 8 is provided with two rows of axially arranged small holes 10, the small holes 10 in each row are uniformly arranged in the circumferential direction, and the diameter of each small hole 10 is smaller than the critical diameter of hydrogen combustion, wherein the small holes in the rear row are connected with radial flow guide pipes 11, the front part of each first mixed gas pipe 8 is sleeved with a first air passage 12, the first air passage 12 is fixedly connected with the radial plate 5, and the radial outer end of the flow guide pipe 11 is adjacent to the inner wall of the outer first air passage 12; a hole plate 13 is fixedly arranged in the first mixed gas distribution chamber 1 behind the sealing plate 7, the hole plate 13 is provided with a plurality of uniformly distributed axial small holes; a second gas distribution chamber 16 is arranged outside the second air distribution chamber 2, the rear ends of six second gas pipes 17 uniformly distributed in the circumferential direction pass through the rear end plate of the second air distribution chamber 2 and are connected with the second gas distribution chamber 16, the front end 17-1 of the second gas pipe 17 is outwardly tapered, the outward taper angle is 5-35°, the second gas pipe 17 is located in the second air distribution chamber 2 outside the first mixed gas distribution chamber 1 in the radial direction, the front part of the second gas pipe 17 is arranged in a corresponding second air passage 18, the rear end of the second air passage 18 communicates with the second air distribution chamber 2; the third overfire air passage 19 is arranged between the adjacent two second air passages 18 through a partition plate 21, the rear end of the six third overfire air passages 19 is provided with an inlet 19-1, and the second air passage 18 and the third overfire air passage 19 are arranged in the same circular ring and are spaced apart.

[0019] When the present application is used, the air with pressure is introduced into the secondary air distribution chamber 2, the primary mixed gas is introduced into the primary mixed gas distribution chamber 1 after being premixed with hydrogen and natural gas in a certain proportion, flows into each primary mixed gas pipe 8 through the perforated plate 13, and is injected into the primary air channel 12 at high speed through the micro-mixing device formed by the two rows of small holes 10 in each primary mixed gas pipe 8, mixes with the part of air flowing in through the air inlet hole 4, and then is injected out of the nozzle to burn, forming multiple small flames; the secondary gas hydrogen is introduced into the secondary gas distribution chamber 16, and is injected out of the nozzle at the nozzle end of each secondary gas pipe 17, and part of the air enters each secondary air channel 18 to form the secondary air around each secondary gas pipe 17 to mix and burn with the secondary gas, and the two-stage gas realizes multi-stage combustion; the burnout air in each tertiary burnout air channel 19 is supplied by an independent high-pressure fan, and has a higher air speed compared with the primary and secondary air, and provides the oxygen required for the burnout in the later stage of combustion; the primary air channel 12 or the secondary air channel 18 is arranged outside each primary mixed gas pipe 8 and each secondary gas pipe 17 of the present application, air is independently distributed to the two-stage gas, the uniformity of the air mixing is ensured, the primary mixed gas is injected out of the small holes 10 of the micro-mixing device, the rear row of small holes is connected with the flow guide pipe 11, the primary mixed gas injected out of each row of small holes 10 can be more uniformly mixed with the primary air on the radial plane, multiple small flames with uniform combustion are formed at the outlet of the burner, the ignition and stable combustion of the gas are ensured, local high temperature can be avoided, the generation of thermal NOx is reduced, the air staging is strengthened by the tertiary burnout air, the flue gas mixing in the furnace is improved, the combustion uniformity is improved, and the NOx emission is further reduced; the burner adopts a two-stage gas and three-stage air distribution structure, the primary mixed gas pipes 8 in the inner ring are arranged in multiple rings, the primary mixed gas pipes 8 with a large number can be integrated, the secondary air channels 18 and the tertiary burnout air channels 19 in the outer ring are arranged in the same circle and are spaced apart, the structure is compact, the hydrogen and natural gas can be mixed and burned at high power and high efficiency, and the use range is wide;

[0020] The mixed gas can be rectified through the perforated plate 13, and can enter each primary mixed gas pipe 8 more uniformly, and the radial outer end of the flow 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 plane, and further improve the uniformity of the mixing with the primary air;

[0021] Under the condition that the pressure and flow rate of hydrogen are constant, the critical diameter of hydrogen combustion is a constant value; the diameters of each small hole 10 designed under the stable working condition are all smaller than the critical diameter of hydrogen combustion, which can prevent hydrogen from backfiring; the outer expansion cone at the front end of the secondary gas pipe 17 can increase the backflow and entrainment of the flue gas in the furnace, and further improve the combustion uniformity;

[0022] The foregoing examples have been presented with the purpose of illustration and description, and are not intended to limit the application to the scope of the embodiments described.

Claims

1. A hydrogen-enriched natural gas burner comprising a primary mixed gas distribution chamber, a secondary air distribution chamber sleeved outside the primary mixed gas distribution chamber; characterized in that: The front end of the primary mixed gas distribution chamber is connected with a primary air distribution chamber, the primary air distribution chamber is provided with a plurality of air inlet holes communicating with the secondary air distribution chamber, a radial plate is fixedly arranged in the front part of the primary air distribution chamber, and the radial plate is provided with a plurality of air distribution holes; a sealing plate is fixedly arranged in the primary mixed gas distribution chamber, the rear ends of a plurality of primary mixed gas pipes arranged in a plurality of rings and uniformly distributed are fixedly connected with the sealing plate and communicate with the primary mixed gas distribution chamber, the primary mixed gas pipes all pass through the air distribution holes and are closed at the front ends, the front sections of the primary mixed gas pipes are all provided with at least two rows of axial small holes, one row of the small holes is connected with a radial flow guide pipe, the front sections of the primary mixed gas pipes are all sleeved with primary air channels, the primary air channels are all fixedly connected with the radial plate; a secondary gas distribution chamber is arranged outside the secondary air distribution chamber, the rear ends of a plurality of circumferentially distributed secondary gas pipes pass through the secondary air distribution chamber and are connected with the secondary gas distribution chamber, the secondary gas pipes are all arranged in the secondary air distribution chamber outside the primary mixed gas distribution chamber in the radial direction, the front sections of the secondary gas pipes are all arranged in the secondary air channels, the rear ends of the secondary air channels communicate with the secondary air distribution chamber; a plurality of tertiary overfire air channels are arranged between the adjacent secondary air channels, and the rear ends of the tertiary overfire air channels are provided with inlets.

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

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

4. A hydrogen-enriched natural gas burner as claimed in claim 3, characterized in that: The front end of the secondary gas pipe is an outwardly expanding cone, and the outward expansion angle is 5-35°.

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

6. A hydrogen-enriched natural gas burner as claimed in claim 5, characterized in that: The small holes in each row are circumferentially and uniformly arranged. The diameters of the small holes in each row are all less than the critical diameter of hydrogen combustion.

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