Methane-hydrogen mixed gas flow rate self-adaptive combustion test system and test method

Abstract

The present application provides a kind of methane hydrogen-doped flow rate adaptive combustion test system and test method, for solving the technical problems of low combustion efficiency, unstable combustion, high nitrogen oxide emission and uneven mixing of methane and hydrogen in traditional diffusion combustion system.The present application makes methane and hydrogen mix uniformly by first mixing tank, and adjusts and displays the mass flow of methane and hydrogen by gas mass flow controller;Annular bluff body and swirler are set on the upper end of gas injection pipe, the annular bluff body is located in the second section of air injection pipe, and its outer diameter gradually increases from bottom to top;Displacement platform is set on the outer wall of gas injection pipe;The annular bluff body provided by the present application makes air form a stable backflow zone, and the annular bluff body is axially displaced by displacement platform, for controlling the jet velocity of the second section of air injection pipe, while combining with swirler to enhance the mixing of fuel and air, effectively ensuring the combustion stability of methane hydrogen-doping.

Description

Technical Field

[0001] This invention relates to combustion testing, and more particularly to a methane hydrogen-doped flow rate adaptive combustion testing system and method. Background Technology

[0002] Hydrogen energy is a clean, efficient, and renewable energy source, widely used in fuel cells, gas turbines, and internal combustion engines. Hydrogen can be produced through water electrolysis, natural gas steam reforming, and biomass gasification, with abundant resources and production technologies available. Methane is a common natural gas with high calorific value, is clean, and easy to store and transport. The combustion of methane primarily produces carbon dioxide and water, making it a relatively environmentally friendly energy source. Methane-hydrogen blending technology mixes methane and hydrogen in a specific ratio, combining the advantages of both to achieve more efficient combustion while effectively reducing carbon emissions.

[0003] However, due to the high combustion speed and wide combustion limit range of hydrogen, while methane has a relatively slow combustion speed, the combustion of hydrogen-blended methane fuel in traditional combustion systems suffers from unstable combustion, low combustion efficiency, and high nitrogen oxide emissions when the fuel mixes with air in the combustion chamber. Furthermore, existing diffusion combustion systems typically use straight pipes or three-way valves for mixing methane and hydrogen, leading to uneven mixing and affecting combustion stability. Therefore, establishing a hydrogen-blended methane combustion test system to study flame stability, temperature field distribution, and outlet pollutant formation patterns is of great significance. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of low combustion efficiency, unstable combustion, high nitrogen oxide emissions, and uneven mixing of methane and hydrogen in traditional diffusion combustion systems, and to provide a methane-hydrogen-infused flow rate adaptive combustion test system and test method.

[0005] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0006] A methane hydrogen-doped flow rate adaptive combustion test system, characterized in that it includes a gas distribution unit, a combustion unit, and a monitoring unit;

[0007] The gas distribution unit includes a fuel gas distribution module and an air gas distribution module;

[0008] The fuel gas distribution module includes a first branch, a second branch, and a first mixing tank. The inlet ends of the first branch and the second branch are used to input methane and hydrogen, respectively, and the outlet ends of both branches are connected to the first mixing tank to mix methane and hydrogen in the first mixing tank to form methane-hydrogen blended fuel.

[0009] Gas mass flow controllers are installed on the first branch and the second branch respectively, for adjusting and displaying the mass flow of the first branch and the second branch respectively;

[0010] The combustion unit includes a support base, an annular nozzle, and a combustion chamber;

[0011] The annular nozzle includes a gas nozzle located at the center and an air nozzle coaxially sleeved on the outside of the gas nozzle; the air nozzle includes an air nozzle section one and an air nozzle section two.

[0012] The support base includes an annular bracket and a horizontal base plate fixedly connected to the upper end of the annular bracket; a first through hole is provided on the horizontal base plate, the upper end of a first section of the air nozzle passes through the first through hole and communicates with the lower end of a second section of the air nozzle, and the first section of the air nozzle is fixed on the horizontal base plate.

[0013] The lower end of the air nozzle section is sealed, and an air inlet is provided on its side wall for communication with the air distribution module; the gas nozzle is fixedly connected to the air nozzle section, and the lower end of the gas nozzle extends out of the lower end face of the air nozzle section and communicates with the first mixing tank.

[0014] The upper end of the gas nozzle is provided with an annular blunt body that communicates with the gas nozzle. The annular blunt body is located inside the second section of the air nozzle, and its outer diameter gradually increases from bottom to top. The upper end of the annular blunt body and the upper end of the second section of the air nozzle are both connected to the lower end of the combustion chamber.

[0015] A displacement platform is provided on the outer wall of the section of the gas nozzle that extends out of the air nozzle. The displacement platform is used to drive the gas nozzle to move axially, thereby realizing the axial displacement of the annular blunt body.

[0016] The monitoring unit is used to monitor the flame color, flame structure, temperature distribution, and flue gas composition in the combustion chamber in real time.

[0017] Furthermore, an upper limit ring, a vortex generator, and a lower limit ring are sequentially fitted onto the outer wall of the two sections of the gas nozzle corresponding to the air nozzle from top to bottom;

[0018] The upper and lower limit rings are fixed on the outer wall of the gas nozzle, and the cyclone separator can rotate circumferentially relative to the gas nozzle.

[0019] A 1-2mm gap is provided between the lower end face of the upper limit ring and the upper end face of the hydrocyclone, and a 1-2mm gap is provided between the upper end face of the lower limit ring and the lower end face of the hydrocyclone.

[0020] Furthermore, a first flange is fitted onto the upper end of one section of the air nozzle;

[0021] The lower end of the second section of the air nozzle is fitted with a second flange;

[0022] The upper end face of the first flange is abutted with the lower end face of the second flange to form a mating part; the mating part is fixed on the upper surface of the horizontal base plate to connect the second section of the air nozzle with the first section of the air nozzle and to fix the first section of the air nozzle on the horizontal base plate.

[0023] Furthermore, it also includes sealing end caps, pressure caps, and pressure gaskets respectively fitted onto the outer wall of the gas nozzle;

[0024] The upper end of the pressure cap is provided with a first external thread, and the lower end of a section of the air nozzle is provided with a second external thread;

[0025] The sealing end cap is provided with a first internal thread and a second internal thread at both ends, which are used to engage with the first external thread and the second external thread respectively, so that the pressure cap is fixedly connected to the lower end of a section of the air nozzle.

[0026] The pressure pad is located between the sealing end cap and the pressure cap, and is used to seal a section of the air nozzle.

[0027] Furthermore, a preheater is installed on the connecting pipeline between the outlet end of the air distribution module and the air inlet of a section of the air nozzle.

[0028] Furthermore, the angle between the outer wall of the annular blunt body and the plane containing the lower end face is 30°~75°.

[0029] Furthermore, the angle between the outer wall of the annular blunt body and the plane containing the lower end face is 70°;

[0030] The displacement platform adopts a dovetail groove platform;

[0031] The outer edge of the swirling blades on the cyclone separator is fitted with a clearance between it and the inner wall of the second section of the air nozzle.

[0032] The lower end of the inner wall of the annular blunt body is provided with an internal thread, and the upper end of the outer wall of the gas nozzle is provided with an external thread that matches the internal thread, so that the annular blunt body and the gas nozzle are connected through threaded engagement.

[0033] Furthermore, the tilt angle of the swirling blades on the hydrocyclone is 45~65°.

[0034] Furthermore, the air distribution module includes a third branch, a fourth branch, and a second mixing tank. The inlet ends of the third and fourth branches are used to input oxygen and nitrogen respectively, and the outlet ends are both connected to the second mixing tank to allow oxygen and nitrogen to mix in the second mixing tank to form air.

[0035] Gas mass flow controllers are installed on the third and fourth branches respectively, for adjusting and displaying the flow rates of the third and fourth branches respectively;

[0036] The air inlet of one section of the air nozzle is used to connect with the second mixing tank;

[0037] The first branch, the second branch, the third branch, and the fourth branch have the same structure, each including a ball valve, a pressure reducing valve, a solenoid valve, a flame arrester, and a pressure gauge arranged in the order of gas input and output on the corresponding branch.

[0038] The gas mass flow controller is installed between the pressure reducing valve and the solenoid valve;

[0039] The pressure gauge is installed between the pressure reducing valve and the gas mass flow meter to measure the gas pressure entering the mass flow meter.

[0040] The inlet ends of the pressure reducing valves on the first branch, the second branch, and the third branch are respectively provided with bypasses for inputting nitrogen into the first branch, the second branch, and the third branch respectively.

[0041] This invention also provides a method for adaptive combustion testing of methane with hydrogen doping flow rate, characterized by the following steps:

[0042] 1) Construct the above-mentioned methane hydrogen-doped flow rate adaptive combustion test system;

[0043] 2】The methane-hydrogen blended fuel in the first mixing tank and the air in the air distribution module are respectively supplied into the gas injector and the first section of the air injector, and then ignited and started;

[0044] 3) Conduct regulation tests.

[0045] 3.1】First stage: Keeping the initially set hydrogen blending ratio and mass flow rate of methane-blended fuel unchanged, monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition in the combustion chamber when the equivalence ratio and the annular bluff body are in different positions.

[0046] 3.2】Second stage: Keeping the initially set mass flow rate of methane-blended fuel constant, change the hydrogen blending ratio of methane-blended fuel, and monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition of the combustion chamber when the equivalence ratio is different and the annular bluff body is in different positions.

[0047] 3.3】Third stage: Keeping the initially set hydrogen blending ratio of methane-hydrogen fuel unchanged, change the mass flow rate of methane-hydrogen fuel, and monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition of the combustion chamber when the equivalence ratio and the annular bluff body are in different positions.

[0048] 3.4】Fourth stage: Keep the mass flow rate of the methane-blended fuel in step 3.3】 unchanged, change the hydrogen blending ratio of the methane-blended fuel, and monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition of the combustion chamber when the equivalence ratio is different and the annular bluff body is located in different positions.

[0049] Based on the monitored flame color, flame structure, temperature distribution, and exhaust gas emissions at each stage, the corresponding control strategies are as follows: If the flame appears yellowish or turbid, or if soot or CO concentration at the outlet increases, the equivalence ratio is reduced; if the highest monitored temperature exceeds the temperature threshold, the hydrogen blending ratio or equivalence ratio of the methane-blended fuel is reduced; if the monitored outlet nitrogen oxide concentration increases beyond the threshold, the hydrogen blending ratio of the methane-blended fuel is reduced; if the flame is observed to be flickering, have an unclear outline, or vibrate violently, the equivalence ratio is reduced and the position of the annular blunt body is adjusted.

[0050] 4. When the four indicators of combustion chamber flame color, flame organization morphology, temperature distribution and outlet flue gas emission composition in steps 3.1-3.4 all reach the set values, the recorded mass flow rate, hydrogen blending ratio, equivalence ratio and position of the annular bluff body of the methane blended with hydrogen fuel are used as the combustion set values ​​to complete the combustion test.

[0051] The advantages of this invention compared to the prior art are as follows:

[0052] 1. This invention provides a methane-hydrogen blending flow rate adaptive combustion test system. It achieves precise control of different hydrogen blending ratios and equivalence ratios through a gas mass flow controller in the fuel distribution module, and achieves uniform mixing of methane and hydrogen through a first mixing tank. Compared to the conventional straight pipe or three-way method, this improves the uniformity and safety of the mixed gas. Uniform blending of methane and hydrogen effectively reduces carbon emissions, increases flame combustion rate, shortens ignition delay, and prevents backfire during diffusion combustion. Simultaneously, this invention uses a displacement platform to drive an annular bluff body to achieve axial displacement, changing the flow area between the annular bluff body and the second-stage nozzle of the air nozzle, thereby controlling the air jet velocity of the air nozzle. This allows the outlet velocity of the second-stage air nozzle to adapt to changes in air mass flow rate under different hydrogen blending scenarios, enhancing the chemical-turbulent interaction between fuel and air, avoiding flame instability problems such as flame lift-off, blow-out, or flame detachment, and effectively ensuring the combustion stability of methane-hydrogen blended with hydrogen.

[0053] 2. The methane hydrogen-blended flow rate adaptive combustion test system provided by this invention includes a swirler installed in the second section of the air nozzle. The swirling of the swirler effectively enhances the mixing of fuel and air during diffusion combustion, reduces flame temperature, and thus enhances flame stability and reduces nitrogen oxides. In addition, compared with conventional fixed swirlers, this invention has a 1-2mm gap between the upper and lower limit rings and the swirler, forming a follow-up swirler. The follow-up strong swirler can reduce airflow resistance, reduce equipment operating costs, and the rotation speed of the swirler blades is affected by the strength of the incoming airflow, generating adaptive circular rotation around the axis, achieving good flexible control effect under a wide range of operating conditions.

[0054] 3. The methane hydrogen-blending flow rate adaptive combustion test system provided by the present invention combines the axial displacement of the annular bluff body with a cyclone separator, which enhances the controllability of the chemical-turbulent interaction during the combustion process, making it suitable for a wider range of hydrogen-blending operation conditions.

[0055] 4. Compared with traditional air nozzles, the present invention divides the air nozzle into one section and two sections, which are connected and fixed by the first flange and the second flange, making it easier to replace and adjust the annular blunt body and the cyclone.

[0056] 5. The methane hydrogen-doped flow rate adaptive combustion test system provided by the present invention has a preheater installed on the air delivery pipeline, which can increase the initial temperature of the air, thereby improving the combustion efficiency and greatly avoiding the losses caused by incomplete combustion.

[0057] 6. The methane hydrogen-doped flow rate adaptive combustion test system provided by the present invention has an angle of 30°~75° between the outer wall of the annular blunt body and the plane containing the lower end face, which can effectively improve the stability of flame combustion.

[0058] 7. Based on the above-mentioned methane hydrogen-blended flow rate adaptive combustion test system, the present invention provides a methane hydrogen-blended flow rate adaptive combustion test method that is simple, convenient, and highly operable. It can quickly obtain the combustion setpoints of methane hydrogen-blended mass flow rate, hydrogen blending ratio, equivalence ratio, and annular bluff body position, thereby achieving optimization and control of the combustion process. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of an embodiment of a methane hydrogen-doped flow rate adaptive combustion test system of the present invention (monitoring unit and support base are not shown).

[0060] Figure 2 This is a schematic diagram of the combustion unit in an embodiment of the methane hydrogen-doped flow rate adaptive combustion test system of the present invention;

[0061] Figure 3This is a schematic diagram of the structure of an air nozzle section, a gas nozzle, and a displacement platform in an embodiment of the present invention;

[0062] Figure 4 for Figure 3 Sectional view along the middle AA;

[0063] Figure 5 This is a schematic diagram of the annular blunt body structure in an embodiment of the present invention;

[0064] Figure 6 This is a schematic diagram of the gas nozzle, cyclone separator, and annular blunt body structure in an embodiment of the present invention;

[0065] Figure 7 This is a front view of the cyclone separator in an embodiment of the present invention;

[0066] Figure 8 for Figure 7 Top view;

[0067] Figure 9 The following are streamline diagrams of three types of combustion devices: one with only an annular bluff body, one with an annular bluff body and a cyclone separator, and ...

[0068] Figure 10 The diagram shows the axial temperature distribution at the center of the combustion chamber for three types of combustion devices: one with only an annular bluff body, one with an annular bluff body and a cyclone separator and an axial displacement of the annular bluff body relative to the combustion chamber inlet end of 0 mm, and one with an annular bluff body and a cyclone separator and an axial displacement of the annular bluff body relative to the combustion chamber inlet end of 10 mm.

[0069] Figure 11 The diagram shows the NO emission at the combustion chamber outlet for three types of combustion devices: one with only an annular bluff body, one with an annular bluff body and a cyclone separator, and ... respectively.

[0070] The specific labeling in the attached diagram is as follows:

[0071] 1-Gas distribution unit, 11-Fuel gas distribution module, 111-First branch, 112-Second branch, 113-First mixing tank, 12-Air gas distribution module, 121-Third branch, 122-Fourth branch, 123-Second mixing tank, 13-Gas mass flow controller, 14-Ball valve, 15-Pressure reducing valve, 16-Solenoid valve, 17-Flame arrester;

[0072] 2-Combustion unit; 21-Support base; 211-Annular bracket; 212-Horizontal base plate; 22-Combustion chamber; 3-Gas injection pipe; 4-Air injection pipe; 41-Air injection pipe section 1; 411-Air inlet; 42-Air injection pipe section 2; 43-First flange; 44-Second flange; 45-Upper limit ring; 46-Swirl generator; 47-Lower limit ring; 5-Annular blunt body; 6-Displacement platform; 7-Pressure cap; 8-Sealing end cap; 9-Pressure gasket; 10-Preheater. Detailed Implementation

[0073] To make the advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0074] like Figure 1 As shown, a methane-hydrogen blending flow rate adaptive combustion test system includes a gas distribution unit 1, a combustion unit 2, and a monitoring unit. The gas distribution unit 1 is used to control, adjust, and supply the gas required for the test, realizing the blending of methane with hydrogen (fuel) and air.

[0075] The gas distribution unit 1 includes a fuel gas distribution module 11 and an air gas distribution module 12. The fuel gas distribution module 11 includes a first branch 111, a second branch 112, and a first mixing tank 113; the air gas distribution module 12 includes a third branch 121, a fourth branch 122, and a second mixing tank 123.

[0076] The inlet ends of the first branch 111, the second branch 112, the third branch 121, and the fourth branch 122 are respectively used to connect to methane cylinders, hydrogen cylinders, oxygen cylinders, and nitrogen cylinders, so as to input methane into the first branch 111, the second branch 112, the third branch 121, and the fourth branch 122 respectively. ),hydrogen( ),oxygen( ) and nitrogen ( The outlets of the first branch 111 and the second branch 112 are both connected to the first mixing tank 113, which is used to mix methane and hydrogen in the first mixing tank 113 to form methane-hydrogen blended fuel; the outlets of the third branch 121 and the fourth branch 122 are both connected to the second mixing tank 123, which is used to mix oxygen and nitrogen in the second mixing tank 123 to form air.

[0077] Specifically, ball valve 14, pressure reducing valve 15, solenoid valve 16, gas mass flow meter 13, flame arrester 17, and pressure gauge are installed on the first branch 111, the second branch 112, the third branch 121, and the fourth branch 122. Among them, ball valve 14, pressure reducing valve 15, solenoid valve 16, gas mass flow meter 13, and flame arrester 17 are arranged in the order of gas input and output. The pressure gauge is installed between the pressure reducing valve 15 and the gas mass flow meter 13 to measure the gas pressure entering the gas mass flow meter 13. The gas mass flow meter 13 is used to regulate and display the mass flow rate of the gas in the first branch 111, the second branch 112, the third branch 121, and the fourth branch 122, namely the mass flow rate of methane, hydrogen, oxygen, and nitrogen. Taking the first branch 111 as an example, methane exiting the methane cylinder passes through ball valve 14 and pressure reducing valve 15 to reduce pressure to the required level, then enters gas mass flow meter 13. To ensure safety, it then passes through solenoid valve 16 and flame arrester 17 before entering the first mixing tank 113. Similarly, hydrogen from the second branch 112 passes through ball valve 14, pressure reducing valve 15, gas mass flow meter 13, solenoid valve 16, and flame arrester 17 before entering the first mixing tank 113. A certain proportion of methane and hydrogen are mixed evenly in the first mixing tank 113 to form a methane-hydrogen blended fuel. Likewise, a certain proportion of oxygen and nitrogen from the third branch 121 and fourth branch 122 are mixed evenly in the second mixing tank 123 to form air. In this invention, other components in actual air are not considered; the air entering the burner is generally a mixture of 21% oxygen and 79% nitrogen. In other embodiments of this invention, compressed air or purchased air can also be used directly.

[0078] The theoretical reaction equation for the combustion of methane blended with hydrogen fuel is as follows:

[0079] (1)

[0080] In the above formula, Indicates the hydrogen doping ratio. , This represents the mole fraction of hydrogen. This indicates the mole fraction of methane.

[0081] At this point, the stoichiometric ratio of air to hydrogen-blended methane fuel required for combustion is:

[0082] (2)

[0083] in, Indicates air quality, Indicates the mass of methane-blended fuel. This indicates the molar mass of oxygen. This indicates the molar mass of nitrogen gas. This indicates the molar mass of methane. This indicates the molar mass of hydrogen gas.

[0084] When the mass flow rate of methane-blended fuel is When the equivalence ratio (fuel coefficient) is φ, the mass flow rate of air is... and the gas mass flow rate of the four branches , , , They are respectively:

[0085] (3)

[0086] (4)

[0087] (5)

[0088] (6)

[0089] (7)

[0090] in, This indicates the density of oxygen. Indicates the density of air. This indicates the density of nitrogen gas.

[0091] Formulas (2)-(7) are compiled into a calculation program. The mass flow rate, hydrogen blending ratio, and equivalence ratio of the methane-hydrogen blended fuel required for combustion are set on the computer. According to the above calculation program, the required gas flow rates of the first branch 111, the second branch 112, the third branch 121, and the fourth branch 122 can be calculated. Based on the required gas flow rates of the first branch 111, the second branch 112, the third branch 121, and the fourth branch 122, the corresponding gas mass flow controllers 13 are adjusted to achieve the set requirements of the mass flow rate, hydrogen blending ratio, and equivalence ratio of the methane-hydrogen blended fuel.

[0092] Furthermore, in this embodiment, a bypass connected to the inlet of the fourth branch 122 is added to the first branch 111, the second branch 112, and the third branch 121, respectively, for inputting nitrogen into the first branch 111, the second branch 112, and the third branch 121. The bypass at the inlet of the pressure reducing valve 15 on each branch for nitrogen input serves two purposes: firstly, nitrogen can be used for pipeline cleaning and gas replacement before operating at different hydrogen doping ratios and equivalence ratios; secondly, timely nitrogen purging of the system can prevent the accumulation of residual hydrogen and methane gases, thereby preventing an explosion during ignition.

[0093] like Figures 2-4As shown, the combustion unit 2 includes a support base 21, an annular nozzle, a combustion chamber 22, a sealing end cap 8, a pressure cap 7, and a pressure gasket 9. The annular nozzle includes a gas nozzle 3 located at the center and an air nozzle 4 coaxially sleeved on the outside of the gas nozzle 3. The air nozzle 4 includes an air nozzle section 41 and an air nozzle section 42.

[0094] The support base 21 includes an annular bracket 211 and a horizontal base plate 212 fixedly connected to the upper end of the annular bracket 211. A first through hole is provided on the horizontal base plate 212. An air nozzle section 41 passes through the first through hole and a first flange 43 is fitted on its upper end. A second flange 44 is fitted on the lower end of the air nozzle section 42. The upper end face of the first flange 43 and the lower end face of the second flange 44 are abutted to form a mating part. The mating part is fixed to the upper surface of the horizontal base plate 212 by bolts, so as to connect the air nozzle section 42 and the air nozzle section 41 and fix the air nozzle section 41 on the horizontal base plate 212.

[0095] The pressure cap 7, sealing end cap 8, and pressure gasket 9 are respectively fitted onto the outer wall of the gas nozzle 3. The upper end of the pressure cap 7 is provided with a first external thread, and the lower end of the air nozzle section 41 is provided with a second external thread; the two ends of the sealing end cap 8 are respectively provided with a first internal thread and a second internal thread, which are used to engage with the first external thread and the second external thread respectively, so that the pressure cap 7 is fixedly connected to the lower end of the air nozzle section 41. The pressure gasket 9 is located between the sealing end cap 8 and the pressure cap 7, and is used to seal the air nozzle section 41.

[0096] An air inlet 411 is provided on the side wall of the first section of the air nozzle 41, and the air inlet 411 is connected to the second mixing tank 123 for delivering the prepared air into the first section of the air nozzle 41. The lower end of the gas nozzle 3 extends out of the lower end face of the first section of the air nozzle 41 and is connected to the first mixing tank 113 for delivering the prepared methane-hydrogen blended fuel into the gas nozzle 3. The combustion chamber 22 is located above the second section of the air nozzle 42 and the gas nozzle 3. After the air and methane-hydrogen blended fuel in the second section of the air nozzle 42 and the gas nozzle 3 are injected, they enter the combustion chamber 22 for final combustion.

[0097] An annular blunt body 5, communicating with the upper end of the gas nozzle 3, is located within the second section 42 of the air nozzle. In this invention, the annular blunt body 5 is inverted conical in shape, meaning its outer diameter gradually increases from bottom to top. Simultaneously, the upper ends of both the annular blunt body 5 and the second section 42 of the air nozzle are connected to the lower end of the combustion chamber 22. Air and methane-blended hydrogen fuel from the second section 42 of the air nozzle and the gas nozzle 3 are injected and enter the combustion chamber 22 for final combustion. The annular blunt body 5 in this invention creates a stable recirculation zone for the air passing through this area, thereby improving the combustion stability of the methane-blended hydrogen fuel.

[0098] Meanwhile, the present invention provides a displacement platform 6 on the outer wall of the section 41 extending from the gas nozzle 3 into the air nozzle. This displacement platform 6 drives the gas nozzle 3 to perform axial displacement, thereby achieving axial displacement of the annular blunt body 5, controlling the jet velocity of the air nozzle 4, and further ensuring combustion stability. In this embodiment, the displacement platform 6 is a dovetail groove platform; other forms of axial displacement platforms can also be used in other embodiments of the present invention.

[0099] Specifically, such as Figure 5 As shown, the lower end of the inner wall of the annular blunt body 5 is provided with an internal thread, and the upper end of the outer wall of the gas nozzle 3 is provided with an external thread adapted to the internal thread. The annular blunt body 5 and the gas nozzle 3 are connected by the threaded engagement. To achieve stable gas supply, it is preferable that the inner diameter d of the annular blunt body 5 is equal to the inner diameter of the gas nozzle 3. At the same time, considering the changes in the height and displacement stroke of the annular blunt body 5, the angle θ between the outer wall of the annular blunt body 5 and the plane containing the lower end face is set to 30°~75°. The outer radius of the upper end of the annular blunt body 5 is denoted as l1, and the outer radius of the lower end is denoted as l2. Therefore, the length of l2 is consistent with the outer radius of the gas nozzle 3, i.e., l2=5mm. At the same time, since the annular blunt body 5 extends into the second section 42 of the air nozzle, the length of l1 should be less than the outer radius of the second section 42 of the air nozzle. When the outer radius l1 of the upper end, the outer radius l2 of the lower end, and the angle θ of the annular blunt body 5 are determined, the height H of the annular blunt body 5 can be determined by the following formula:

[0100] .

[0101] like Figure 6 As shown, an upper limit ring 45, a swirler 46, and a lower limit ring 47 are sequentially fitted onto the outer wall of the gas nozzle 3, corresponding to the second section 42 of the air nozzle, from top to bottom. The upper limit ring 45 and lower limit ring 47 are detachably mounted on the outer wall of the gas nozzle 3, and the swirler 46 is rotatable relative to the gas nozzle 3. A 1-2mm gap is provided between the lower end face of the upper limit ring 45 and the upper end face of the swirler 46, and a 1-2mm gap is also provided between the upper end face of the lower limit ring 47 and the lower end face of the swirler 46. Because the upper limit ring 45 and lower limit ring 47 are detachably connected to the outer wall of the gas nozzle 3, the distance between the upper end face of the swirler 46 and the lower end face of the annular blunt body 5 can be adjusted by moving the positions of the upper limit ring 45 and lower limit ring 47. Figure 7 , Figure 8 As shown, the height of the hydrocyclone 46 is h, and swirl blades are provided on it. Since the tilt angle of the swirl blades (the acute angle between the tangent direction of the swirl blades and the vertical direction) α will affect the number of swirls, the tilt angle α of the swirl blades in this invention is preferably set to 45~65°.

[0102] The cyclone separator 46 enhances turbulence through its swirling blades, increasing the mixing degree between the fuel gas and air. Together with the annular blunt body 5, it generates a recirculation zone containing high-temperature gas flow, preheating the incoming ambient-temperature fuel and air to achieve sustained and stable combustion. To prevent leakage between the cyclone separator 46 and the outer wall of the fuel nozzle 3, the inner diameter D of the cyclone separator 46 is... i After adding the blade thickness, it matches the outer diameter of the gas nozzle 3. Meanwhile, if the distance between the outer edge of the cyclone separator 46 blades and the inner wall of the second section 42 of the air nozzle is too small, it will increase the rotational resistance of the cyclone separator 46; if the distance is too large, it will reduce the outer diameter D of the cyclone separator 46. o The reduction in diameter leads to a decrease in swirl intensity; therefore, a clearance fit is preferably used between the outer edge of the swirl blades and the inner wall of the second section of the air nozzle. Swirl intensity is one of the important performance parameters of the swirler 46, and it depends on the inner diameter D. i Outer diameter D o and tilt angle α; swirling intensity is expressed as swirling number. It is expressed as follows:

[0103] .

[0104] Since different hydrogen blending conditions have different effects on combustion, the performance of end-use is also different. The two typical hydrogen blending application scenarios are as follows: (1) Keep the fuel volume flow rate unchanged before and after hydrogen blending. Since the volume calorific value of hydrogen is lower than that of methane, the heat load decreases as the hydrogen blending ratio increases; (2) Keep the fuel input heat power unchanged before and after hydrogen blending. More fuel needs to be introduced as the hydrogen blending ratio increases. Since the air-fuel stoichiometric ratio of hydrogen combustion is higher than that of methane, if the equivalence ratio remains unchanged in both application scenarios, the air mass flow rate needs to be reduced accordingly as the hydrogen blending ratio in natural gas increases. At this time, the air nozzle is axially displaced by the displacement platform 6 to change the flow area between the annular blunt body 5 and the nozzle of the second section 42 of the air nozzle. This allows the outlet velocity of the second section 42 of the air nozzle to adapt to the change in air mass flow rate, avoiding flame instability problems such as flame lift-off, blow-out, or flame detachment. Meanwhile, since there is a 1-2mm movable gap between the upper limit ring 45 and the lower limit ring 47 and the cyclone separator 46, when the air flow velocity is greater than the cyclone separator's starting speed, the adaptive strong cyclone separator 46 can be passively rotated under the action of the air flow. Compared with the fixed cyclone separator, the flow resistance is reduced to a certain extent. Furthermore, by adjusting the positions of the upper limit ring 45 and the lower limit ring 47, the relative position of the cyclone separator 46 and the annular blunt body 5 can be adjusted. The coupling between the two will effectively change the size of the recirculation zone generated in the combustion chamber 22 and the mixing with high-temperature reactants, thereby controlling the flame stability under different hydrogen doping conditions.

[0105] Furthermore, the increased initial air temperature raises the combustion temperature and accelerates the combustion reaction. Therefore, in this embodiment, a preheater 10 is installed on the connecting pipe between the outlet of the air distribution module 12 and the inlet 411 of the air nozzle section 41. This increases the initial air temperature, thereby improving combustion efficiency and significantly reducing losses caused by incomplete combustion. Preferably, the preheater 10 in the test system uses resistance wire heating, and a temperature controller is used to control the heating temperature to achieve reasonable preheating. In practical industrial applications, high-temperature flue gas or high-temperature exhaust gas can also be fully utilized to preheat the air, achieving waste heat recovery, reducing exhaust gas temperature, reducing exhaust gas losses, and achieving energy saving and consumption reduction. Simultaneously, both the air distribution module 12 and the fuel distribution module 11 are equipped with solenoid valves and flame arresters at their outlets, with the corresponding solenoid valve and flame arrester on the air distribution module 12 located at the front end of the preheater 10.

[0106] The monitoring unit is used to monitor the flame color, flame structure, temperature distribution, and exhaust gas composition of the combustion chamber 22 in real time. Real-time monitoring of the flame color, flame structure, exhaust gas composition, and temperature distribution of the combustion chamber 22 can be achieved using existing technologies.

[0107] Since the combustion chamber 22 is typically made of quartz glass, this embodiment includes a high-speed camera on its outer side. This camera allows observation of the flame color, flame structure, and stability (flame lift-off, blow-out, and flame detachment) through the transparent quartz glass. Simultaneously, a cover is installed at the upper outlet of the combustion chamber 22 to allow the combustion gases to converge and be exhausted by an explosion-proof fan through a universal ventilation hood. A flue gas sampling gun is placed horizontally near the combustion chamber outlet, and the collected flue gas is analyzed using a portable multi-functional flue gas analyzer to measure the concentrations of O2, CO, CO2, and nitrogen oxides. Temperature-measuring thermocouples are evenly spaced on the side walls of the combustion chamber 22, allowing for the measurement of the radial temperature distribution within the combustion chamber 22.

[0108] The advantages of the present invention will be further illustrated below through comparative experiments.

[0109] The combustion unit model of this invention is established based on the following dimensions: the inner diameter of the gas nozzle 3 is 4 mm, the outer diameter is 10 mm, and the inner diameter of the air nozzle 4 is 30 mm. The outer radius of the upper end of the annular blunt body 5 is l1 = 10 mm, the outer radius of its lower end is l2 = 5 mm, the angle between the outer wall of the annular blunt body 5 and the plane containing its lower end surface is 70°, and the height H = 13.7 mm. The stroke of the displacement platform 6 is 100 mm; the inner diameter D of the cyclone separator 46 is... i and outer diameter D oThe diameters are 12mm and 30mm respectively, the tilt angle α of the swirl blades is 45°, the corresponding number of swirls is 0.74, the number of swirl blades is 5, the height h of the swirler 46 is 15mm, and the distance between the lower end face of the annular blunt body 5 and the upper end face of the swirler 46 can be adjusted within 0~20mm; the length and width of the quartz glass visible combustion chamber are both 140mm, and the height is 500mm.

[0110] Taking a 20% hydrogen-blended methane fuel with an equivalence ratio of 0.4 lean combustion as an example, when the fuel inlet velocity is 5 m / s, computational fluid dynamics simulations are used to compare the flow field, temperature field, and nitrogen oxide emission characteristics of three combustion devices: one with only annular bluff body 5, one with annular bluff body 5 and cyclone separator 46 in combination with annular bluff body 5 and axial displacement of annular bluff body 5 relative to the inlet end of combustion chamber 22 of 0 mm, and one with annular bluff body 5 and cyclone separator 46 in combination with annular bluff body 5 and axial displacement of annular bluff body 5 relative to the inlet end of combustion chamber 22 of 10 mm.

[0111] Figure 9 The diagrams show three types of combustion devices. (a) shows the combustion device with only the annular blunt body 5; (b) shows the combustion device where the annular blunt body 5 is coupled to the swirler 46 and the axial displacement of the annular blunt body 5 relative to the inlet end of the combustion chamber 22 is 0 mm; and (c) shows the combustion device where the annular blunt body 5 is coupled to the swirler 46 and the axial displacement of the annular blunt body 5 relative to the inlet end of the combustion chamber 22 is 10 mm. It can be seen that… Figure 9 In (a), a vortex is generated behind the annular blunt body 5. When combined with the cyclone separator 46, Figure 9 (b) generates a larger radial velocity, the vortex moves towards the center, and Figure 9 (c) shows a more obvious velocity vector flowing back to the annular blunt body 5, which is beneficial for bringing high-temperature reactants into the fresh main gas flow, thus playing a role in fixing the continuous ignition source and improving the instability of hydrogen-doped combustion.

[0112] Figure 10 The combustion chamber temperature distribution diagrams are for three types of combustion devices: one with only annular blunt body 5, one with annular blunt body 5 and swirler 46 in cooperation with annular blunt body 5 and axial displacement of annular blunt body 5 relative to the inlet end of combustion chamber 22 of 0 mm, and one with annular blunt body 5 and swirler 46 in cooperation with annular blunt body 5 and axial displacement of annular blunt body 5 relative to the inlet end of combustion chamber 22 of 10 mm. It can be seen that due to the cooperation between annular blunt body 5 and swirler 46, the air generates radial velocity, the flame spreads to both sides of combustion chamber 22, and the temperature at the central axial position decreases.

[0113] Figure 11The diagram shows the NOx emissions at the combustion chamber outlet for three types of combustion devices: one with only the annular blunt body 5, the annular blunt body 5 coupled with the cyclone separator 46 with an axial displacement of 0 mm relative to the inlet end of the combustion chamber 22, and the annular blunt body 5 coupled with the cyclone separator 46 with an axial displacement of 10 mm relative to the inlet end of the combustion chamber 22. It can be seen that when the annular blunt body 5 is coupled with the cyclone separator 46 and the axial displacement of the annular blunt body 5 relative to the inlet end of the combustion chamber 22 is 0 mm and 10 mm, the NO emissions at the combustion chamber 22 outlet are reduced by 57.0% and 22.1%, respectively, compared to when only the annular blunt body 5 is used.

[0114] This invention also provides a method for adaptive combustion testing of methane with hydrogen doping flow rate, specifically including the following steps:

[0115] 1. Construct the above-mentioned methane hydrogen-doped flow rate adaptive combustion test system.

[0116] 2】The methane-hydrogen blended fuel in the first mixing tank 113 and the air in the air distribution module 12 are respectively supplied into the gas injector 3 and the first section of the air injector 41, and then ignited and started;

[0117] 3) Conduct regulation tests.

[0118] 3.1】First stage: Keeping the initially set hydrogen blending ratio and mass flow rate of methane blended with hydrogen unchanged, monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition in combustion chamber 22 when the equivalence ratio and the annular bluff body 5 are in different positions; in this embodiment, the initially set hydrogen blending ratio of methane blended with hydrogen fuel is 10% and the mass flow rate of methane blended with hydrogen fuel is 3L / min.

[0119] 3.2】Second stage: Keep the mass flow rate of methane blended with hydrogen fuel constant at 3L / min, and adjust the hydrogen blending ratio of methane blended with hydrogen fuel within the range of 0%-80%. Monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition of combustion chamber 22 when the equivalence ratio and the annular blunt body 5 are in different positions.

[0120] 3.3】Third stage: Keep the hydrogen blending ratio of methane-hydrogen fuel at 10%, change the mass flow rate of methane-hydrogen fuel to 6L / min, and monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition of the combustion chamber when the equivalence ratio and the annular blunt body 5 are in different positions.

[0121] 3.4】Fourth stage: Keep the mass flow rate of methane with hydrogen constant in step 3.3】, change the hydrogen ratio of methane with hydrogen, and monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition of the combustion chamber when the equivalence ratio and the annular blunt body 5 are in different positions.

[0122] In steps 3.1-3.4, the equivalence ratio is adjusted within the range of 0.4-1.4, and the axial displacement of the annular blunt body 5 relative to the inlet end of the combustion chamber 22 is 0mm-10mm.

[0123] Based on the monitored flame color, flame structure, temperature distribution, and exhaust gas composition at each stage, the corresponding control strategies are as follows: If the flame appears yellowish or turbid, or if soot or CO concentration at the outlet increases, it indicates insufficient fuel-air mixture and incomplete combustion. In this case, the equivalence ratio should be reduced by increasing the airflow. If the highest monitored temperature exceeds the temperature threshold, considering the material lifespan and safety under long-term high-temperature operation, the hydrogen blending ratio or equivalence ratio of the methane-blended fuel needs to be reduced. If the monitored outlet nitrogen oxide concentration increases beyond the threshold, thermal nitrogen oxides may increase due to the increased temperature after hydrogen blending. In this case, the hydrogen blending ratio of the methane-blended fuel needs to be reduced. If the flame is observed to be flickering, with an unclear outline, or violently vibrating, it indicates flame instability and may result in flame lift-off or flameout. In this case, the equivalence ratio needs to be reduced, and the position of the annular blunt body 5 needs to be adjusted.

[0124] 4】When the four indicators of combustion chamber flame color, flame organization morphology, temperature distribution and outlet flue gas emission composition in steps 3.1-3.4 all reach the set values, the mass flow rate of methane blended with hydrogen fuel, hydrogen blending ratio, equivalence ratio and position of annular blunt body 5 are taken as the combustion set values ​​to complete the combustion test.

[0125] The above description is only used to illustrate the technical solutions of the present invention, and is not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

1. A methane hydrogen-doped flow rate adaptive combustion test system, characterized in that: It includes a gas distribution unit (1), a combustion unit (2), and a monitoring unit; The gas distribution unit (1) includes a fuel gas distribution module (11) and an air gas distribution module (12). The fuel distribution module (11) includes a first branch (111), a second branch (112), and a first mixing tank (113). The inlet ends of the first branch (111) and the second branch (112) are used to input methane and hydrogen respectively, and the outlet ends are connected to the first mixing tank (113) to mix methane and hydrogen in the first mixing tank (113) to form methane-hydrogen blended fuel. Gas mass flow controllers (13) are installed on the first branch (111) and the second branch (112) respectively, for adjusting and displaying the mass flow of the first branch (111) and the second branch (112) respectively; The combustion unit (2) includes a support base (21), an annular nozzle, and a combustion chamber (22); The annular nozzle includes a gas nozzle (3) located at the center and an air nozzle (4) coaxially sleeved on the outside of the gas nozzle (3); the air nozzle (4) includes an air nozzle section (41) and an air nozzle section (42). The support base (21) includes an annular bracket (211) and a horizontal base plate (212) fixedly connected to the upper end of the annular bracket (211); a first through hole is provided on the horizontal base plate (212), the upper end of the first section of the air nozzle (41) passes through the first through hole and communicates with the lower end of the second section of the air nozzle (42), and the first section of the air nozzle (41) is fixed on the horizontal base plate (212); The lower end of the air nozzle section (41) is sealed, and an air inlet (411) is provided on its side wall for communication with the air distribution module (12); the gas nozzle (3) is connected to the air nozzle section (41), and the lower end of the gas nozzle (3) extends out of the lower end face of the air nozzle section (41) and communicates with the first mixing tank (113). The upper end of the gas nozzle (3) is provided with an annular blunt body (5) that communicates with the gas nozzle (3). The annular blunt body (5) is located inside the second section (42) of the air nozzle, and its outer diameter gradually increases from bottom to top. The upper end of the annular blunt body (5) and the upper end of the second section (42) of the air nozzle are both connected to the lower end of the combustion chamber (22). A displacement platform (6) is provided on the outer wall of the section (41) of the gas nozzle (3) extending out of the air nozzle. The displacement platform (6) is used to drive the gas nozzle (3) to make axial displacement, thereby realizing the axial displacement of the annular blunt body (5). The monitoring unit is used to monitor the flame color, flame structure, temperature distribution, and exhaust gas composition of the combustion chamber (22) in real time.

2. The methane hydrogen-doped flow rate adaptive combustion test system according to claim 1, characterized in that: The gas nozzle (3) is fitted with an upper limit ring (45), a vortex generator (46) and a lower limit ring (47) on the outer side wall of the second section (42) of the air nozzle from top to bottom. The upper limit ring (45) and the lower limit ring (47) are fixed on the outer wall of the gas nozzle (3), and the cyclone separator (46) can rotate circumferentially relative to the gas nozzle (3). A gap of 1-2 mm is provided between the lower end face of the upper limit ring (45) and the upper end face of the hydrocyclone (46), and a gap of 1-2 mm is provided between the upper end face of the lower limit ring (47) and the lower end face of the hydrocyclone (46).

3. The methane hydrogen-doped flow rate adaptive combustion test system according to claim 2, characterized in that: The upper end of the air nozzle section (41) is fitted with a first flange (43). The lower end of the second section (42) of the air nozzle is fitted with a second flange (44). The upper end face of the first flange (43) is connected to the lower end face of the second flange (44) to form a mating part; the mating part is fixed on the upper surface of the horizontal base plate (212) to connect the second section (42) of the air nozzle with the first section (41) of the air nozzle, and to fix the first section (41) of the air nozzle on the horizontal base plate (212).

4. The methane hydrogen-doped flow rate adaptive combustion test system according to claim 3, characterized in that: It also includes a sealing end cap (8), a pressure cap (7), and a pressure gasket (9) respectively fitted on the outer wall of the gas nozzle (3); The upper end of the pressure cap (7) is provided with a first external thread, and the lower end of the air nozzle section (41) is provided with a second external thread; The sealing end cap (8) is provided with a first internal thread and a second internal thread at both ends, which are used to engage with the first external thread and the second external thread respectively, so that the pressure cap (7) is fixedly connected to the lower end of a section (41) of the air nozzle; The pressure pad (9) is located between the sealing end cap (8) and the pressure cap (7) to achieve a seal on a section (41) of the air nozzle.

5. The methane hydrogen-doped flow rate adaptive combustion test system according to claim 4, characterized in that: A preheater (10) is installed on the connecting pipeline between the outlet end of the air distribution module (12) and the air inlet (411) of the first section of the air nozzle (41).

6. The methane hydrogen-doped flow rate adaptive combustion test system according to claim 5, characterized in that: The angle between the outer wall of the annular blunt body (5) and the plane containing the lower end face is 30°~75°.

7. The methane hydrogen-doped flow rate adaptive combustion test system according to claim 6, characterized in that: The angle between the outer wall of the annular blunt body (5) and the plane containing the lower end face is 70°; The displacement platform (6) adopts a dovetail groove platform; The outer edge of the swirling blades on the swirler (46) is fitted with a clearance between the inner wall of the second section (42) of the air nozzle; The lower end of the inner wall of the annular blunt body (5) is provided with an internal thread, and the upper end of the outer wall of the gas nozzle (3) is provided with an external thread that matches the internal thread, so that the annular blunt body (5) and the gas nozzle (3) are connected by thread engagement.

8. The methane hydrogen-doped flow rate adaptive combustion test system according to claim 7, characterized in that: The tilt angle of the swirling blades on the cyclone separator (46) is 45~65°.

9. A methane hydrogen-doped flow rate adaptive combustion test system according to any one of claims 1-8, characterized in that: The air distribution module (12) includes a third branch (121), a fourth branch (122), and a second mixing tank (123). The inlet ends of the third branch (121) and the fourth branch (122) are used to input oxygen and nitrogen respectively, and the outlet ends are connected to the second mixing tank (123) to mix oxygen and nitrogen in the second mixing tank (123) to form air. Gas mass flow controllers (13) are installed on the third branch (121) and the fourth branch (122) respectively, for adjusting and displaying the flow rates of the third branch (121) and the fourth branch (122) respectively; The air inlet (411) of the first section (41) of the air nozzle is used to communicate with the second mixing tank (123); The first branch (111), the second branch (112), the third branch (121) and the fourth branch (122) have the same structure, and each includes a ball valve (14), a pressure reducing valve (15), a solenoid valve (16) and a flame arrester (17) arranged in the order of gas input and output on the corresponding branch. The gas mass flow controller (13) is installed between the pressure reducing valve (15) and the solenoid valve (16); A pressure gauge is installed between the pressure reducing valve (15) and the gas mass flow controller (13) to measure the gas pressure entering the gas mass flow controller (13); The inlet end of the pressure reducing valve (15) on the first branch (111), the second branch (112) and the third branch (121) is provided with a bypass for inputting nitrogen gas into the first branch (111), the second branch (112) and the third branch (121) respectively.

10. A method for adaptive combustion testing of methane with hydrogen doping flow rate, characterized in that, Includes the following steps: 1) Construct a methane hydrogen-doped flow rate adaptive combustion test system as described in any one of claims 1-9; 2】The methane-hydrogen blended fuel in the first mixing tank (113) and the air in the air distribution module (12) are respectively supplied into the gas injector (3) and the first section of the air injector (41), and then ignited and started; 3) Conduct regulation tests. 3.1】First stage: Keep the hydrogen blending ratio and mass flow rate of the methane-blended fuel unchanged, and monitor and record the flame color, flame structure, temperature distribution and exhaust gas composition in the combustion chamber (22) when the equivalence ratio and the annular bluff body (5) are in different positions. 3.2】Second stage: Keep the mass flow rate of the methane-hydrogen blended fuel unchanged, change the hydrogen blending ratio of the methane-hydrogen blended fuel, and monitor and record the flame color, flame organization morphology, temperature distribution and exhaust gas composition of the combustion chamber when the equivalence ratio and the annular bluff body (5) are located in different positions. 3.3】Third stage: Keep the initially set hydrogen blending ratio of methane-hydrogen fuel unchanged, change the mass flow rate of methane-hydrogen fuel, and monitor and record the flame color, flame organization morphology, temperature distribution and outlet flue gas emission components of the combustion chamber when the equivalence ratio and the annular bluff body (5) are located in different positions respectively. 3.4】Fourth stage: Keep the mass flow rate of the methane-blended fuel in step 3.3】 unchanged, change the hydrogen blending ratio of the methane-blended fuel, and monitor and record the flame color, flame organization morphology, temperature distribution and exhaust gas composition of the combustion chamber when the equivalence ratio and the annular bluff body (5) are located in different positions respectively. Based on the monitored flame color, flame structure, temperature distribution, and exhaust gas composition, the corresponding control strategies for each stage are as follows: if the flame appears yellowish or turbid, or if soot or CO concentration at the outlet increases, the equivalence ratio is reduced; if the highest monitored temperature exceeds the temperature threshold, the hydrogen blending ratio or equivalence ratio of the methane-blended fuel is reduced; if the monitored outlet nitrogen oxide concentration increases beyond the threshold, the hydrogen blending ratio of the methane-blended fuel is reduced; if the observed flame is flickering, has an unclear outline, or vibrates violently, the equivalence ratio is reduced and the position of the annular blunt body (5) is adjusted. 4】When the four indicators of combustion chamber flame color, flame organization morphology, temperature distribution and outlet flue gas emission composition in steps 3.1-3.4 all reach the set values, the recorded mass flow rate of methane blended with hydrogen fuel, hydrogen blending ratio, equivalence ratio and position of annular bluff body (5) are used as the combustion set values ​​to complete the combustion test.

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