Water vapor diluted hydrogen fuel-pure oxygen cyclone diffusion combustor

Abstract

This invention discloses a steam-diluted hydrogen fuel-pure oxygen swirling diffusion burner, comprising a burner shell, an oxygen pipeline, and a hydrogen pipeline. The oxygen pipeline is located inside the burner shell, with its outer wall forming a first steam channel between the inner wall of the burner shell and the outer wall of the oxygen pipeline. The hydrogen pipeline is located inside the oxygen pipeline, with its outer wall forming a second steam channel between the inner wall of the hydrogen pipeline and the outer wall of the hydrogen pipeline. The outlet ends of the oxygen pipeline and the hydrogen pipeline are flush and both connected to the combustion chamber, forming a four-layer co-directional swirling combustion structure of steam-oxygen-steam-hydrogen from the outside to the inside. The oxygen pipeline adopts a double-wall structure, with an annular pressure-stabilizing chamber formed between the two layers. The outlet end of the pressure-stabilizing chamber is connected by an annular plate with several oxygen injection holes, and the inlet end is connected by an annular plate with several oxygen inlet pipes. This invention can achieve stable and efficient hydrogen combustion conversion with a hydrogen / oxygen inlet ratio close to 1, under different dilution ratios and power, achieving near or zero emissions.

Description

Technical Field

[0001] This invention belongs to the field of power engineering and engineering thermophysics, and specifically relates to a steam-diluted hydrogen fuel-pure oxygen swirling diffusion burner. Background Technology

[0002] Pure oxygen combustion using water vapor dilution is a promising hydrogen energy conversion method. This method, by replacing nitrogen in the air with water vapor as a diluent, theoretically completely avoids NOx formation, resulting in completely clean emissions. When using hydrocarbon fuels, low-cost, high-purity CO2 capture can be achieved through simple condensation separation. Related gas turbine combined cycle systems can achieve high thermal efficiencies of 55-65%. While the addition of a diluent helps control the adiabatic flame temperature, suppresses backfire, and prevents overheating damage to the combustion chamber structure and turbine blades, it also slows down flame propagation speed and ignition delay time, which is detrimental to flame stability and achieving high combustion efficiency.

[0003] The addition of water to hydrogen-oxygen combustion has three main effects on flame velocity: 1) dilution effect, 2) thermal diffusion effect, and 3) chemical effect. The addition of a diluent has multiple effects on the pure oxygen combustion flame. The most significant macroscopic effect is the alteration of laminar flame velocity and thermal properties, which in turn affects combustion stability and purge characteristics. On the other hand, to maximize fuel / oxygen utilization, pure oxygen combustion requires a near-stoichiometric ratio. However, when hydrogen-oxygen-vapor combustion is near-stoichiometric, the accumulation of residual oxygen can lead to oxidation of downstream metal components, and excessive accumulation of residual hydrogen, if not promptly removed, can even cause an explosion. Therefore, to achieve industrially applicable pure oxygen combustion, combustion efficiency needs to be improved. Thus, while traditional hydrogen combustion chamber techniques such as swirl combustion, staged combustion, DLN (diffusion-needle combustion), and MILD (mild combustion) can effectively reduce emissions and maintain flame stability, they are not suitable for pure oxygen combustion. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner, so as to achieve stable and efficient hydrogen combustion conversion with different dilution ratios and power under hydrogen / oxygen intake conditions with an equivalence ratio close to 1, and to approach or reach zero emissions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner includes a burner shell, an oxygen pipeline, and a hydrogen pipeline; The oxygen pipeline is located inside the burner housing, and a first water vapor channel is formed between its outer wall and the inner wall of the burner housing. The hydrogen pipeline is located inside the oxygen pipeline, and a second water vapor channel is formed between its outer wall and the inner wall of the oxygen pipeline. The outlet end of the oxygen pipeline is flush with the outlet end of the hydrogen pipeline and both are connected to the combustion chamber, forming a four-layer co-directional swirling combustion structure of water vapor-oxygen-water vapor-hydrogen from the outside to the inside.

[0006] In one embodiment, the first steam passage is provided with an external vortex generator, which causes the steam introduced through the first steam passage to form a vortex, creating a recirculation zone in the combustion chamber.

[0007] In one embodiment, an internal cyclone separator is provided in the hydrogen pipeline.

[0008] In one embodiment, the outer wall of the outlet end of the hydrogen pipeline extends outward to connect with the inner wall of the outlet end of the oxygen pipeline, and a plurality of water vapor nozzles communicating with the second water vapor channel are provided on the connection end face. The water vapor of the second water vapor channel is ejected from the water vapor nozzles to isolate hydrogen and oxygen.

[0009] In one embodiment, the oxygen pipeline adopts a double-wall structure, with an annular pressure-stabilizing cavity formed between the double-wall structure. The outlet end of the pressure-stabilizing cavity is connected to an annular plate with several oxygen nozzles, and the inlet end is connected to an annular plate with several oxygen inlet pipes.

[0010] In one embodiment, the axial dimension of the pressure stabilizing chamber is smaller than the axial dimension of the hydrogen pipeline, and the burner housing has several steam inlet pipes connected to the outside of the pressure stabilizing chamber.

[0011] In one embodiment, the swirling blades of the outer swirler rotate clockwise at an angle of 30-60°; the tangential direction of the oxygen nozzle is clockwise with a swirling angle of 30-60°; and the swirling blades of the inner swirler rotate clockwise.

[0012] In one embodiment, the equivalence ratio of oxygen introduced through the oxygen pipeline to hydrogen introduced through the hydrogen pipeline is 0.95-1, and the molar flow rate of the water vapor is 5-15 of that of the oxygen.

[0013] In one embodiment, the flow rate ratio of water vapor introduced into the first water vapor channel to water vapor introduced into the second water vapor channel is automatically allocated. With the first water vapor channel being a ring with an inner diameter of 30 mm and an outer diameter of 54 mm, and the second water vapor channel being a ring with an outer diameter of 14 mm and an inner diameter of 10 mm, and the inner and outer channel area ratio being 20:1, the flow rate ratio is 20:1.

[0014] In one embodiment, the combustion chamber employs a flared, funnel-shaped opening.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) The combustion organization method of hydrogen / oxygen / water vapor in the same direction is adopted to effectively address the problem of low combustion efficiency of pure oxygen and incomplete hydrogen-oxygen reaction under hydrogen fuel equivalence ratio. At the same time, it improves the combustion stability when the water vapor dilution ratio is high, and realizes efficient hydrogen-oxygen conversion.

[0016] (2) Traditional steam dilution pure oxygen burners either use pre-mixed steam and oxygen supply or supply steam alone for cooling, which cannot simultaneously ensure combustion stability and temperature regulation range. This invention adopts an automatic steam distribution design, which allows a portion of the steam to pass through the gap between the hydrogen and oxygen pipelines, avoiding premature contact between hydrogen and oxygen, actively raising the flame to protect the burner head. At the same time, due to the low proportion of steam, the hydrogen-oxygen combustion stability is good, and most of the steam forms a backflow in the outer layer, mixing with the combustion products to achieve tail gas temperature regulation.

[0017] (3) This invention is a single-head burner, whose structural design contains only 5 main parts, making it easy to process and assemble. This invention is very convenient to use; it only requires installing the burner into the combustion chamber and connecting the hydrogen, oxygen, and steam pipelines. For actual combustion chamber requirements, the single-head burner structure can be used as a basis to form a combustion chamber head design suitable for different power levels by arranging multiple burner units in an array. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 This is the isometric drawing of the present invention.

[0020] Figure 3 This is a top view of the present invention.

[0021] Figure 4 This is a rendering of the assembly of the present invention (1 / 4 cross-section).

[0022] Figure 5 This is a detailed structural schematic diagram (isometric view) of an oxygen pipeline in an embodiment of the present invention.

[0023] Figure 6 yes Figure 5 Top view of the oxygen pipeline.

[0024] Figure 7 yes Figure 5 Front view of the oxygen pipeline.

[0025] Figure 8 yes Figure 7 Sectional view of AA.

[0026] Figure 9 This is a detailed structural schematic diagram (isometric view) of a hydrogen pipeline in an embodiment of the present invention.

[0027] Figure 10 yes Figure 9 Top view of the oxygen pipeline.

[0028] Figure 11 This is a detailed structural schematic diagram (isoaxial view) of an external cyclone in an embodiment of the present invention.

[0029] Figure 12 yes Figure 11 Front view of the external cyclone separator.

[0030] Figure 13 yes Figure 11 Top view of the external cyclone.

[0031] Figure 14 This is a detailed structural schematic diagram (isometric view) of an internal cyclone in an embodiment of the present invention.

[0032] Figure 15 yes Figure 14 Front view of the internal cyclone separator.

[0033] Figure 16 yes Figure 14 Right view of the internal vortex.

[0034] Figure 17 This is a detailed structural schematic diagram (isoaxial) of the burner housing in an embodiment of the present invention. Figure 1 ).

[0035] Figure 18 This is a detailed structural schematic diagram (isoaxial) of the burner housing in an embodiment of the present invention. Figure 2 ).

[0036] Figure 19 yes Figure 17 , Figure 18 Front view of the burner housing.

[0037] Figure 20 yes Figure 17 , Figure 18 Top view of the burner housing.

[0038] Figure 21 This is a schematic diagram of the simulation results of an embodiment of the present invention. Detailed Implementation

[0039] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0040] This invention relates to a steam-diluted hydrogen fuel-pure oxygen swirling diffusion burner. Targeting hydrogen flames with high adiabatic flame temperatures and high flame propagation velocities, it avoids NOx formation through pure oxygen combustion while simultaneously regulating flame temperature through steam dilution. The swirling diffusion combustion mechanism prevents backfire and maintains good combustion stability and efficiency at different power / dilution ratios.

[0041] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the present invention mainly includes a burner housing 4, an oxygen pipeline 3, and a hydrogen pipeline 1. In this invention, these three main components are preferably coaxially arranged, from the outside in: the burner housing 4, the oxygen pipeline 3, and the hydrogen pipeline 1. The three components can be connected by a fixing member at the bottom, which is not shown in the figure.

[0042] Among them, such as Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, the oxygen pipeline 3 adopts a double-walled structure, with the first wall on the outside and the second wall on the inside in the radial direction. The outer wall of the oxygen pipeline 3 of this invention is the outer wall of the first wall, and the inner wall of the oxygen pipeline 3 of this invention is the inner wall of the second wall. An annular pressure-stabilizing cavity 3-2 is formed between the double-walled structures of the oxygen pipeline 3. The outlet end of the pressure-stabilizing cavity 3-2 is connected to an annular plate with several oxygen nozzles 3-1, and the inlet end is connected to an annular plate with several oxygen inlet pipes 3-3.

[0043] The oxygen line 3 is located inside the burner housing 4 and has a gap. Specifically, the gap between the outer wall of the oxygen line 3 and the inner wall of the burner housing 4 forms a first steam channel. The outlet end of the oxygen line 3 is designed to connect to the combustion chamber.

[0044] The hydrogen pipeline 1 is located inside the oxygen pipeline 3 and is spaced apart. Specifically, the gap between the outer wall of the hydrogen pipeline 1 and the inner wall of the oxygen pipeline 3 forms a second water vapor channel. The outlet end of the hydrogen pipeline 1 is also connected to the combustion chamber.

[0045] Therefore, the burner of this invention forms a four-layer co-current swirling combustion structure of water vapor-oxygen-water vapor-hydrogen from the outside in, creating a strong reflux zone in the hydrogen-oxygen reaction region. This increases the residence time of unreacted hydrogen and oxygen in the high-temperature zone, thus improving the pure oxygen combustion efficiency at a hydrogen fuel equivalence ratio and enhancing combustion stability at a high water vapor dilution ratio. Simultaneously, the water vapor introduced through the second water vapor channel acts as an isolation barrier between hydrogen and oxygen, preventing the high-temperature flame formed by hydrogen and oxygen from damaging the burner. Therefore, it is necessary to design the outlet end of the oxygen pipeline 3 to be flush with the outlet end of the hydrogen pipeline 1.

[0046] In one embodiment of the present invention, such as Figure 9 and Figure 10 As shown, at the outlet ends of hydrogen pipeline 1 and oxygen pipeline 3, the outer wall of hydrogen pipeline 1 extends outward to connect with the inner wall of oxygen pipeline 3, i.e., they are connected through an annular plate structure. This annular plate serves as the connection end face, on which multiple steam nozzles 1-1 communicating with the second steam channel are provided; in this embodiment, there are 12 nozzles. Steam from the second steam channel is ejected from each steam nozzle 1-1 to isolate hydrogen and oxygen.

[0047] In one embodiment of the present invention, an external vortex generator 2 is provided in the first steam channel to cause the steam entering through the first steam channel to form a vortex, creating a recirculation zone in the combustion chamber and regulating the flame temperature. Figure 12 , Figure 13 and Figure 14 As shown, the hydrocyclone has 12 swirling blades, which rotate clockwise at an angle of 30-60°.

[0048] In one embodiment of the present invention, an internal swirler 5 is provided in the hydrogen pipeline 1. The hydrogen pipeline 1 is a hydrogen channel 1-2, in which the hydrogen gas is swirled by the internal swirler 5 before entering the combustion chamber and mixing with oxygen and water vapor to participate in combustion, forming a hydrogen / oxygen diffusion flame with swirling organization in the internal recirculation zone. Figure 14 , Figure 15 and Figure 16 As shown, the blades of the inner cyclone 5 rotate clockwise with a pitch of 20 mm and a blade length of 8 mm. They sweep in a spiral pattern and make one rotation.

[0049] The outer swirler 2 and inner swirler 5 of the present invention can be fixed to the burner housing 4, oxygen pipeline 3 and hydrogen pipeline 1 by interference fit or welding, or they can be manufactured as a whole by 3D printing.

[0050] In one embodiment of the present invention, the axial dimension of the pressure stabilizing chamber 3-2 in the burner housing 4 is smaller than the axial dimension of the hydrogen pipeline 1, such as... Figure 17 , Figure 18 , Figure 19 and Figure 20 As shown, several steam inlet pipes 4-1 are provided on the burner housing 4, and the steam inlet pipes 4-1 are connected to the outside of the pressure stabilizing chamber 3-2. This causes the steam to be divided into two parts, which are sent into the combustion chamber through the first steam channel and the second steam channel, respectively.

[0051] Under actual operating conditions, the dilution ratio of the steam in this invention, based on the exhaust temperature design, may be in the range of 5-15 (i.e., 3-10 times the molar flow rate of oxygen at the same temperature and pressure), and fluctuates with the upstream pressure. In this design, steam enters from two opposing steam inlet pipes 4-1 on the burner shell 4, and then mixes and stabilizes within the cavity. Subsequently, most of the steam passes through the outer vortex 2 to form a vortex flow and enters the combustion chamber, forming a reflux zone and regulating the flame temperature, ensuring a high combustion efficiency at the equivalence ratio. At the same time, a small amount of steam is ejected from the steam nozzle 1-1 through the narrow gap formed by the oxygen pipe 3 and the hydrogen pipe 1, isolating hydrogen and oxygen, actively raising the flame to protect the burner, preventing premature contact between hydrogen and oxygen, and actively raising the flame to protect the burner head. Furthermore, due to the low proportion of steam, the hydrogen-oxygen combustion stability is good, and most of the steam forms a reflux in the outer layer, mixing with the combustion products to achieve exhaust gas temperature regulation, enabling the flame to achieve stable and efficient combustion at different dilution ratios.

[0052] This invention employs an automatic steam distribution design, where the flow rates of the two steam components are automatically distributed (controlled by the total outlet area of ​​the steam nozzle 1-1 and the outlet area of ​​the outer cyclone separator). With the first steam channel being a ring with an inner diameter of 30 mm and an outer diameter of 54 mm, and the second steam channel being a ring with an outer diameter of 14 mm and an inner diameter of 10 mm, and the ratio of the inner and outer channel areas being 20:1, simulations show that the inner steam flow rate is approximately 1 / 20 of the outer flow rate.

[0053] In one embodiment of the present invention, the oxygen nozzles 3-1 are tangential holes, numbering 12. The oxygen pipeline 3 has four centrally symmetrical oxygen inlet pipes 3-3. Oxygen enters the pressure stabilizing chamber 3-2 through each oxygen inlet pipe 3-3, and is then distributed within the pressure stabilizing chamber 3-2 before being ejected through the 12 tangentially inclined oxygen nozzles 3-1, forming a fine, swirling oxygen supply. Specifically, the tangential direction is clockwise, with a swirling angle of 30-60°.

[0054] By employing the tangential design of the outer swirler 2, the inner swirler 5, and the oxygen nozzle 3-1, this invention achieves a highly efficient and stable three-swirling diffusion burner design, resulting in a stable and efficient combustion organization scheme. On one hand, the diffusion combustion organization method avoids the risk of backfire; on the other hand, the three-stage swirling combustion organization method creates a strong backflow zone to match the flame propagation speed under different dilution ratios.

[0055] In one embodiment of the present invention, the combustion chamber adopts a funnel-shaped flare, which mainly serves to guide the formation of swirl.

[0056] Figure 21 A simulation result of the burner of the present invention is shown, under the following operating conditions: Power (kW) Water vapor molar flow rate / oxygen molar flow rate Water vapor inlet temperature (K) Hydrogen / Oxygen inlet temperature (K) Export pressure (atm) 5 7 500 273 1 The results show the time-averaged values ​​of temperature at the burner's central longitudinal section, H2O / O2 / H2 mole fractions, Y-direction velocity, and chemical reaction exothermic rate. The test results indicate that the burner flow field can form a recirculation zone, exhibiting diffusion flame structure characteristics, good combustion stability, and efficient fuel combustion and conversion, thus achieving the predetermined combustion organization goals.

Claims

1. A steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner, characterized in that, It includes a burner housing (4), an oxygen pipeline (3) and a hydrogen pipeline (1); the oxygen pipeline (3) adopts a double-wall structure, and an annular pressure stabilizing chamber (3-2) is formed between the double-wall structure. The outlet end of the pressure stabilizing chamber (3-2) is connected to an annular plate with several oxygen injection holes (3-1), and the inlet end is connected to an annular plate with several oxygen inlet pipes (3-3). The oxygen pipeline (3) is located inside the burner housing (4), and a first water vapor channel is formed between its outer wall and the inner wall of the burner housing (4); The hydrogen pipeline (1) is located inside the oxygen pipeline (3), and a second water vapor channel is formed between its outer wall and the inner wall of the oxygen pipeline (3); The outlet end of the oxygen pipeline (3) is flush with the outlet end of the hydrogen pipeline (1) and both are connected to the combustion chamber, forming a four-layer co-current swirling combustion structure of water vapor-oxygen-water vapor-hydrogen from the outside to the inside.

2. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 1, characterized in that, The first steam passage is equipped with an external vortex generator (2) to make the steam entering through the first steam passage form a vortex and form a recirculation zone in the combustion chamber.

3. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 2, characterized in that, An internal cyclone separator (5) is installed in the hydrogen pipeline (1).

4. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 3, characterized in that, The oxygen nozzle (3-1) is a tangential nozzle.

5. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 4, characterized in that, The outer cyclone separator (2) has cyclone blades that rotate clockwise at an angle of 30-60°; the oxygen nozzle (3-1) has a tangential direction of clockwise rotation at an angle of 30-60°; the inner cyclone separator (5) has cyclone blades that rotate clockwise; or, The outer cyclone (2) has cyclone blades that rotate counterclockwise at an angle of 30-60°; the oxygen nozzle (3-1) has a tangential direction that rotates counterclockwise at an angle of 30-60°; and the inner cyclone (5) has cyclone blades that rotate counterclockwise.

6. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 1, characterized in that, The outer wall of the outlet end of the hydrogen pipeline (1) extends outward to connect with the inner wall of the outlet end of the oxygen pipeline (3), and a plurality of water vapor nozzles (1-1) communicating with the second water vapor channel are provided on the connection end face. The water vapor of the second water vapor channel is ejected from the water vapor nozzles (1-1) to isolate hydrogen and oxygen.

7. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 1, characterized in that, The axial dimension of the pressure stabilizing chamber (3-2) is smaller than the axial dimension of the hydrogen pipeline (1). Several steam inlet pipes (4-1) are opened on the burner shell (4), and the steam inlet pipes (4-1) are connected to the outside of the pressure stabilizing chamber (3-2).

8. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 1, characterized in that, To ensure that the hydrogen and oxygen react as completely as possible, the equivalent ratio of oxygen introduced into the oxygen pipeline (3) to hydrogen introduced into the hydrogen pipeline (1) is 0.95-1. To control the temperature, the molar flow rate of the water vapor is 5-15 times that of the oxygen.

9. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 1, characterized in that, The flow rate ratio of water vapor introduced into the first water vapor channel to water vapor introduced into the second water vapor channel is automatically allocated. With the first water vapor channel being a ring with an inner diameter of 30 mm and an outer diameter of 54 mm, and the second water vapor channel being a ring with an outer diameter of 14 mm and an inner diameter of 10 mm, and the inner and outer channel area ratio being 20:1, the flow rate ratio is 20:

1.

10. The steam-diluted hydrogen fuel-pure oxygen swirl diffusion burner according to claim 1, characterized in that, The combustion chamber adopts a flared, funnel-shaped opening.

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