Clean combustion method of ammonia fuel

Abstract

The invention discloses a clean combustion method of ammonia fuel, which realizes systematic purification gain through three-field dynamic coupling of a flow field, a reaction field and a sound field. The metal cage serves as a structured reactor, the grid structure of the metal cage reshapes a flame peripheral flow field, a stable low-speed vortex region is formed, the retention time of pollutants is prolonged, and favorable conditions are created for catalytic reaction. The composite catalyst loaded on the cage body efficiently captures and converts pollution molecules in the optimized flow field; periodic pressure oscillation is introduced into sound waves with specific frequency, a gas boundary layer is disturbed, mass transfer driving force of pollutants to the surface of the catalyst is greatly enhanced, the surface of the catalyst is continuously scoured through micro-scale gas flow pulsation, and a dynamic online self-cleaning mechanism is formed; the platinum, the copper and the lanthanum strontium cobalt iron form a closed loop of a metal cage optimized flow field, sound wave enhanced mass transfer and cleaning and efficient conversion of the catalyst, in-situ deep purification of pollutants is achieved, and the initiative platinum-copper-lanthanum strontium cobalt iron composite catalyst constructs an oxidation-reduction dual-function synergistic system.

Description

Technical Field

[0001] This invention relates to the field of clean combustion and pollution control technology, specifically to a clean combustion method for ammonia fuel. Background Technology

[0002] Ammonia, as a zero-carbon energy carrier, produces no carbon dioxide during combustion, making it a promising candidate for energy transition. However, pure ammonia fuel suffers from inherent drawbacks such as high flame temperature, slow flame propagation speed, and poor combustion stability, hindering its direct application in conventional equipment. Currently, blending ammonia with hydrocarbon fuels (such as natural gas and diesel) has become the mainstream technical approach to improve its engineering feasibility. While this method can stabilize the flame by leveraging the excellent combustion characteristics of hydrocarbon fuels, it simultaneously introduces the more complex challenge of synergistic control of pollutants, especially nitrogen oxides (NOx). x The emission problem of ammonia is particularly prominent. As a nitrogen-containing fuel, the combustion of ammonia produces fuel-type NO. x The process generates a large number of pollutants, including thermal NO at high temperatures. x The generation of NO was also extremely significant, leading to its NO x The emission concentration is far higher than that of conventional fuels, which constitutes the primary bottleneck for its clean utilization.

[0003] When using ammonia-hydrogen mixed fuels, the flue gas pollutants exhibit significant multi-component and complex characteristics. On the one hand, ammonia combustion itself produces high concentrations of NO. x Furthermore, the incomplete combustion of hydrocarbon components generates carbon monoxide (CO), particulate matter, and unburned hydrocarbons (UHCs). This results in a complex system of multiple gaseous and particulate pollutants in the final emissions, posing stringent requirements for the simultaneous removal of multiple targets in treatment technologies.

[0004] The large-scale application of ammonia fuel is one of the important potential pathways to achieve carbon neutrality. It has significant advantages over pure hydrogen in terms of storage, transportation, and energy density, and has become a key hub in the hydrogen energy economic chain. However, the maturity of ammonia fuel combustion technology currently lags far behind its strategic positioning. Achieving efficient, stable, and clean conversion during combustion is a core technological obstacle hindering its large-scale engineering application. Existing combustion organization and after-treatment technologies often focus on controlling single or a few pollutants, making it difficult to achieve synergistic and long-term suppression of all pollutants across a wide range of operating conditions, and easily leading to mutual constraints on emission reduction effects and increased energy consumption. Therefore, developing a clean combustion method that can synergistically and effectively suppress the generation and emission of nitrogen oxides, carbon monoxide, soot, and unburned hydrocarbons from the combustion source, based on the combustion characteristics of ammonia fuel, is of significant practical importance for opening up efficient and clean utilization of ammonia fuel and promoting its true status as a reliable zero-carbon energy source. Summary of the Invention

[0005] To achieve the above objectives, this invention provides a method suitable for the combustion of ammonia fuel that can synergistically and effectively suppress nitrogen oxides (NOx). x This invention relates to a method for the generation and emission of carbon monoxide, soot, and unburned hydrocarbons (UHCs). The invention is achieved through the following technical solution:

[0006] This invention discloses a clean combustion method for ammonia fuel, which is implemented using the following combustion apparatus:

[0007] The nozzle is connected to the fuel supply line and delivers ammonia fuel, which is then ignited to form a diffuse flame.

[0008] The metal cage is a hollow cylindrical tubular structure with openings at both ends and a grid structure on its side circumference. It is suspended around the nozzle and in the flame and smoke passage. The nozzle passes through the lower opening of the metal cage, and the metal cage is placed close to the outermost edge of the diffused flame.

[0009] The lifting support includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a connecting clip with orthogonally arranged locking screws and moves up and down along the longitudinal rod. The end of the transverse rod is connected to a metal cage. The lifting support is used to adjust the height of the metal cage.

[0010] A loudspeaker, positioned horizontally on the metal cage, is used to apply sound waves at frequencies of 50-300Hz to the metal cage.

[0011] The surface of the metal cage is loaded with a composite catalyst;

[0012] The method is as follows: ammonia fuel is passed through a vertically upward nozzle and ignited to form a stable diffusion flame; the height of the metal cage is adjusted by a lifting support, and a loudspeaker is activated to apply sound waves of a specific frequency to the metal cage; the combined effect of enhanced mass transfer through acoustic pulsation and catalytic oxidation on the catalyst surface is used to achieve efficient suppression of combustion pollutants.

[0013] As a further improvement, the metal wire mesh of the metal cage described in this invention is made of iron, nickel-based alloy or copper material, with a mesh count of 20-100 mesh and a wire diameter of 0.2-0.6 mm.

[0014] As a further improvement, the distance between the speaker and the flame described in this invention is 100-300mm.

[0015] As a further improvement, the metal cage of the present invention is positioned at a distance of 1-10 mm from the outermost edge of the flame.

[0016] As a further improvement, the upper edge of the metal cage described in this invention extends 20-60 mm from the nozzle.

[0017] As a further improvement, the composite catalyst described in this invention is platinum (Pt), copper (Cu), lanthanum (Lanthanium), strontium (Sr), cobalt (Co), and iron (La). 0.8 Sr 0.2 Co 0.8 Fe 0.2 O3, Pt-Cu-LSCF; its preparation method is as follows:

[0018] Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, and stir evenly to obtain the composite sol.

[0019] As a further improvement, the steps of attaching the metal cage composite catalyst according to the present invention are as follows:

[0020] Step 1: Cut and wind the metal wire mesh into a metal cage of the required size and shape, then place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0021] Step 2: Immerse the pre-oxidized metal cage from Step 1 into the composite sol obtained in claim 6. After full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0022] Step 3: After drying the metal cage impregnated with sol in Step 2, heat it to 650°C in air and calcine it for 4 hours. After natural cooling, the metal cage loaded with the composite catalyst is obtained.

[0023] Step 4: The metal cage loaded with composite catalyst obtained in Step 3 is activated by reducing the metal cage obtained in Step 3 at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage with a stable catalyst coating.

[0024] As a further improvement, the method described in this invention can suppress pollutants generated by ammonia fuel combustion by up to 99%. Furthermore, the suppression effect is characterized by its long-lasting and stable nature.

[0025] Beneficial effects of the present invention

[0026] This invention achieves systematic purification gains through the dynamic coupling of three fields: flow field, reaction field, and acoustic field. The metal cage, acting as a structured reactor, reshapes the flow field around the flame with its grid structure, forming a stable low-velocity vortex zone that prolongs the residence time of pollutants, creating favorable conditions for the catalytic reaction. The composite catalyst supported on the cage efficiently captures and transforms pollutant molecules within this optimized flow field. Acoustic waves of a specific frequency (50–300 Hz) introduce periodic pressure oscillations, which, on the one hand, disturb the gas boundary layer, greatly enhancing the mass transfer driving force of pollutants to the catalyst surface; on the other hand, continuously flush the catalyst surface through microscale airflow pulsations, forming a dynamic "online self-cleaning" mechanism. These three elements constitute a closed loop: "metal cage optimized flow field → acoustic wave enhanced mass transfer and cleaning → efficient catalyst transformation," achieving in-situ deep purification of pollutants.

[0027] This invention pioneered a platinum-copper-lanthanum-strontium-cobalt-iron composite catalyst, constructing a dual-function synergistic system of oxidation-reduction. The Pt-Cu-LSCF composite catalyst system achieves "divide and conquer, synergistic transformation" of multiple pollutants through a precise division of labor among its components. Highly dispersed Pt nanoparticles, acting as dehydrogenation and C / C bond breaking centers, significantly reduce the ignition temperature of soot and heavy UHCs, pre-decomposing them into easily processed small molecules. LSCF perovskite, with its excellent oxygen storage and release capacity, rapidly provides lattice oxygen, completely oxidizing intermediate products such as CO and light UHCs into CO2 and H2O. Cu species, acting as selective catalytic reduction (SCR) active centers, preferentially adsorb and activate unburned NH3, converting it and NOx in situ to N2 on the catalyst surface, precisely solving the problem of fuel-type NOx. The three components form a relay reaction chain of "Pt decomposing large molecules → LSCF oxidizing small molecules → Cu eliminating nitrogen oxides," achieving simultaneous and deep purification of complex pollutants.

[0028] This invention utilizes low-frequency pulsating sound waves, whose controllable pressure pulsation energy effectively thins the gas boundary layer on the catalyst surface, significantly reducing mass transfer resistance. This allows for more efficient transport of pollutants such as soot precursors, CO, and NOx to active sites, comprehensively enhancing the surface reaction rate and breaking through the mass transfer bottleneck in soot conversion. Simultaneously, the microscale airflow shear force induced by the sound waves generates a continuous aerodynamic purging effect, promptly stripping away initially deposited carbon precursors and fly ash particles, preventing the active sites from being covered and delaying catalyst physical deactivation from the source. By strictly controlling the frequency within the optimized range of 50-300 Hz, a good match between the sound field energy and the reactor structure and reaction timescale is ensured, maximizing and sustaining energy input and enhancement effects while avoiding flame instability.

[0029] This method has an efficiency of over 99% in suppressing soot produced by ammonia fuel combustion, and an efficiency of over 99% in suppressing CO and nitrogen oxides, with a long-lasting and stable suppression effect. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the ammonia fuel clean combustion experimental device of the present invention;

[0031] Among them: 1 is the flame, 2 is the metal cage, 3 is the speaker, 4 is the nozzle, and 5 is the lifting bracket.

[0032] Figure 2 This is a schematic diagram of the mesh structure of the metal cage in this invention. Detailed Implementation

[0033] This invention discloses a clean combustion method for ammonia fuel, which is implemented using the following combustion apparatus, such as... Figure 1 As shown:

[0034] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame;

[0035] Metal cage 2 is a hollow cylindrical tubular structure open at both ends, with a grid structure on its side circumference, such as... Figure 2 As shown, the nozzle 4 is suspended around the nozzle 4 in the flame and smoke passage. The nozzle 4 passes through the lower opening of the metal cage 2, and the metal cage 2 is placed close to the outermost edge of the diffused flame.

[0036] The lifting bracket 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a connecting clip with orthogonally arranged locking screws and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting bracket 5 is used to adjust the height of the metal cage 2. The connecting clip with orthogonally arranged locking screws includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a connecting clip with orthogonally arranged locking screws and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting bracket 5 is used to adjust the height of the catalytic metal cage 2. The connecting clip is longitudinally connected to the longitudinal rod and transversely connected to the transverse rod. It is arranged vertically and has locking screws on it for locking and loosening, which are used to adjust the movement of the transverse rod fixed by the connecting clip on the longitudinal rod.

[0037] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0038] The surface of metal cage 2 is supported with a composite catalyst;

[0039] The method is as follows: ammonia fuel is ignited through a vertically upward nozzle 4 to form a stable diffusion flame; the height of the metal cage 2 is adjusted by the lifting bracket 5, and the speaker 3 is activated to apply sound waves of a specific frequency to the metal cage 2; through the combined effect of enhanced mass transfer by acoustic pulsation and catalytic oxidation on the catalyst surface, the combustion pollutants are effectively suppressed.

[0040] The metal wire mesh of the metal cage 2 is made of iron, nickel-based alloy, or copper, with a mesh size of 20-100 and a wire diameter of 0.2-0.6 mm. The distance between the speaker 3 and the flame is 100-300 mm. The distance between the metal cage 2 and the outermost edge of the flame is 1-10 mm. The upper edge of the metal cage 2 extends 20-60 mm above the nozzle 4.

[0041] The composite catalyst is platinum (Pt), copper (Cu), lanthanum (Lanthanum), strontium (Sr), cobalt (Co), and iron (La). 0.8 Sr 0.2 Co 0.8 Fe 0.2 O3, Pt-Cu-LSCF; its preparation method is as follows:

[0042] Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, and stir evenly to obtain the composite sol.

[0043] The steps for attaching the composite catalyst to the metal cage 2 are as follows:

[0044] Step 1: Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape, and then place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0045] Step 2: Immerse the pre-oxidized metal cage 2 from Step 1 into the composite sol obtained in claim 6. After full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0046] Step 3: After drying the metal cage 2 impregnated with sol in Step 2, heat it to 650°C in air atmosphere and calcine it for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0047] Step 4: The metal cage 2 loaded with composite catalyst obtained in Step 3 is activated by reducing the metal cage 2 obtained in Step 3 at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0048] The method can suppress pollutants generated by ammonia fuel combustion by up to 99%, and the suppression effect is long-lasting and stable.

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0050] Example 1

[0051] Combustion device:

[0052] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0053] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0054] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0055] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0056] The surface of metal cage 2 is supported with a composite catalyst;

[0057] Implementation method:

[0058] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0059] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.2 mm and a mesh count of 20). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0060] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0061] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0062] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0063] 6) Ammonia fuel (80% ammonia NH3 + 20% acetylene C2H2) is ignited through the vertically upward nozzle 4 to form a stable diffusion flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5 to control the distance between the metal cage 2 and the outermost edge of the flame 1 to be 1mm, and the upper edge of the metal cage 2 to extend 20mm from the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 100mm and then activated to apply a sound wave with a frequency of 50Hz.

[0064] Tests showed that the carbon soot suppression efficiency reached 95%, CO emission reduction rate was 90%, nitrogen oxide removal rate was 88%, and unburned hydrocarbon (UHCs) removal rate was 85%.

[0065] Example 2

[0066] Combustion device:

[0067] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0068] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0069] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0070] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0071] The surface of metal cage 2 is supported with a composite catalyst;

[0072] Implementation method:

[0073] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0074] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.3 mm and a mesh count of 40). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0075] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0076] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0077] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0078] 6) Ammonia fuel (80% ammonia NH3 + 20% acetylene C2H2) is ignited through a vertically upward nozzle 4 to form a stable diffused flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5 to control the distance between the metal cage 2 and the outermost edge of the flame 1 to be 3mm, and the upper edge of the metal cage 2 to extend 30mm from the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 150mm and then activated to apply a sound wave with a frequency of 100Hz.

[0079] Tests showed that the carbon soot suppression efficiency reached 97%, CO emission reduction rate was 93%, nitrogen oxide removal rate was 92%, and unburned hydrocarbon (UHCs) removal rate was 91%.

[0080] Example 3

[0081] Combustion device:

[0082] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0083] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0084] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0085] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0086] The surface of metal cage 2 is supported with a composite catalyst;

[0087] Implementation method:

[0088] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0089] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.4 mm and a mesh count of 60). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0090] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0091] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0092] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0093] 6) Ammonia fuel (80% ammonia NH3 + 20% acetylene C2H2) is ignited through the vertically upward nozzle 4 to form a stable diffusion flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5 to control the distance between the metal cage 2 and the outermost edge of the flame 1 to be 5mm, and the upper edge of the metal cage 2 to extend 40mm from the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 200mm and then activated to apply a sound wave with a frequency of 150Hz.

[0094] Tests showed that the carbon soot suppression efficiency reached 99%, CO emission reduction rate was 99%, nitrogen oxide removal rate was 99%, and unburned hydrocarbon (UHCs) removal rate was 99%.

[0095] Example 4

[0096] Combustion device:

[0097] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0098] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0099] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0100] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0101] The surface of metal cage 2 is supported with a composite catalyst;

[0102] Implementation method:

[0103] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0104] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.5 mm and a mesh count of 80). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0105] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0106] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0107] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0108] 6) Ammonia fuel (80% ammonia NH3 + 20% acetylene C2H2) is ignited through the vertically upward nozzle 4 to form a stable diffusion flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5 to control the setting distance of the metal cage 2 from the outermost edge of the flame 1 to be 7mm, and the upper edge of the metal cage 2 to extend 50mm from the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 250mm and then activated to apply a sound wave with a frequency of 200Hz.

[0109] Tests showed that the carbon soot suppression efficiency reached 97%, CO emission reduction rate was 94%, nitrogen oxide removal rate was 94%, and unburned hydrocarbon (UHCs) removal rate was 93%.

[0110] Example 5

[0111] Combustion device:

[0112] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0113] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0114] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0115] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0116] The surface of metal cage 2 is supported with a composite catalyst;

[0117] Implementation method:

[0118] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0119] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.6 mm and a mesh count of 100). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0120] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0121] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0122] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0123] 6) Ammonia fuel (80% ammonia NH3 + 20% acetylene C2H2) is ignited through the vertically upward nozzle 4 to form a stable diffusion flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5 to control the setting distance of the metal cage 2 from the outermost edge of the flame 1 to be 10mm, and the upper edge of the metal cage 2 to extend 60mm from the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 300mm and then activated to apply a sound wave with a frequency of 300Hz.

[0124] Tests showed that the carbon soot suppression efficiency reached 97%, CO emission reduction rate was 94%, nitrogen oxide removal rate was 94%, and unburned hydrocarbon (UHCs) removal rate was 92%.

[0125] Example 6

[0126] Combustion device:

[0127] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0128] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0129] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0130] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0131] The surface of metal cage 2 is supported with a composite catalyst;

[0132] Implementation method:

[0133] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0134] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.4 mm and a mesh count of 60). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0135] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0136] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0137] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0138] 6) Ammonia fuel (80% ammonia NH3 + 20% methane CH4) is ignited through a vertically upward nozzle 4 to form a stable diffusion flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5 to control the distance between the metal cage 2 and the outermost edge of the flame 1 to be 5mm, and the upper edge of the metal cage 2 to extend 40mm from the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 200mm and then activated to apply a sound wave with a frequency of 150Hz.

[0139] Tests showed that CO emissions were reduced by 99%, nitrogen oxides were removed by 99%, and unburned hydrocarbons (UHCs) were removed by 99%.

[0140] Example 7

[0141] Combustion device:

[0142] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0143] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0144] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0145] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0146] The surface of metal cage 2 is supported with a composite catalyst;

[0147] Implementation method:

[0148] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0149] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.4 mm and a mesh count of 60). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0150] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0151] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0152] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0153] 6) Ammonia fuel (80% ammonia NH3 + 20% ethylene C2H4) is ignited through a vertically upward nozzle 4 to form a stable diffused flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5, and the distance between the metal cage 2 and the outermost edge of the flame 1 is controlled to be 5mm, and the upper edge of the metal cage 2 is 40mm above the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 200mm and then activated to apply a sound wave with a frequency of 150Hz.

[0154] Tests showed that the carbon soot suppression efficiency reached 99%, CO emission reduction rate was 99%, nitrogen oxide removal rate was 99%, and unburned hydrocarbon (UHCs) removal rate was 99%.

[0155] Example 8

[0156] Combustion device:

[0157] Nozzle 4 is connected to the fuel supply pipeline to deliver ammonia fuel, and ignites it to form a diffuse flame 1;

[0158] The metal cage 2 is a hollow cylindrical tubular structure with openings at both ends. The side circumference is a grid structure. It is suspended around the nozzle 4, in the flame 1 and the flue gas channel. The nozzle 4 passes through the lower opening of the metal cage 2. The metal cage 2 is placed close to the outermost edge of the diffused flame 1.

[0159] The lifting support 5 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a double-top screw cross clamp and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage 2. The lifting support 5 is used to adjust the height of the metal cage 2.

[0160] Speaker 3 is positioned horizontally on the metal cage 2 and is used to apply sound waves with a frequency of 50-300Hz to the metal cage 2.

[0161] The surface of metal cage 2 is supported with a composite catalyst;

[0162] Implementation method:

[0163] 1) Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, stir evenly to obtain the composite sol.

[0164] 2) Cut and wind the metal wire mesh into a metal cage 2 of the required size and shape (the metal cage 2 is made of stainless steel wire mesh with a wire diameter of 0.4 mm and a mesh count of 60). Then, place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, place it in a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace.

[0165] 3) Immerse the pre-oxidized metal cage 2 in 2) into the composite sol obtained in 1), and after full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen.

[0166] 4) After the metal cage 2 impregnated with sol in 3) is dried, it is heated to 650°C in air and calcined for 4 hours. After natural cooling, the metal cage 2 loaded with composite catalyst is obtained.

[0167] 5) The metal cage 2 loaded with composite catalyst obtained in 4) is activated by reducing the metal cage 2 obtained in 4) at 400°C for 2 hours in a hydrogen (H2) atmosphere to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage 2 with a stable catalyst coating.

[0168] 6) Ammonia fuel (pure ammonia gas NH3) is ignited through the vertically upward nozzle 4 to form a stable diffusion flame 1; the height of the metal cage 2 is adjusted by the lifting bracket 5, and the distance between the metal cage 2 and the outermost edge of the flame 1 is controlled to be 5mm, and the upper edge of the metal cage 2 is 40mm above the nozzle 4; the distance between the speaker 3 and the flame 1 is adjusted to 200mm and then activated to apply a sound wave with a frequency of 150Hz.

[0169] The nitrogen oxide removal rate was 99% as tested.

[0170] Compare with Example 1

[0171] No treatment was performed, the metal cage was not installed, the sound waves were turned off, and other conditions were the same as in Example 3.

[0172] The measured pollutant concentration at the outlet is used as the baseline.

[0173] Compare with Example 2

[0174] 2. No metal cage is set up, sound waves are turned on, and other conditions are the same as in Example 3.

[0175] Experimental results showed that the carbon soot suppression rate was 45%, the CO emission reduction rate was 50%, the NOx removal rate was 8%, and the UHCs removal rate was 5%.

[0176] As can be seen, compared with Example 3 and Comparative Examples 1 and 2, when relying solely on sound waves without the catalyst metal cage 2, carbon soot and CO can be suppressed to some extent by improving mixing, but it is almost ineffective for NOx that requires deep catalytic conversion.

[0177] Compare with Example 3

[0178] Set up an unloaded metal cage 2, turn off the sound waves, and keep other conditions the same as in Example 3.

[0179] Experimental results showed that: carbon soot suppression rate was 40%, CO emission reduction rate was 42%, and NO emission reduction rate was 40%. x Removal rate 10%, UHCs removal rate 8%.

[0180] Compare with Example 4

[0181] Set up an unloaded metal cage 2, turn on the sound wave, and other conditions are the same as in Example 3.

[0182] Experimental results showed: carbon soot suppression rate 55%, CO emission reduction rate 53%, NO emission reduction rate 55%. x Removal rate 15%, UHCs removal rate 12%.

[0183] As can be seen, compared with Example 3 and Comparative Examples 3 and 4, the single metal cage 2 has a certain effect on suppressing carbon soot, but its purification effect on other combustion pollutants is not good; the superimposed sound field effect of the metal cage 2 structure enhances the physical suppression effect on carbon soot, but its ability to chemically transform pollutants is still insufficient, and the purification effect is not comprehensive.

[0184] Compare with Example 5

[0185] Set up a metal cage 2 with a load of Pt, turn on the sound wave, and other conditions are the same as in Example 3.

[0186] Experimental results showed that: carbon soot suppression rate was 65%, CO emission reduction rate was 60%, and NO emission reduction rate was 60%. x Removal rate 40%, UHCs removal rate 69%.

[0187] Compare with Example 6

[0188] Set up a metal cage 2 loaded with Cu, turn on the sound wave, and other conditions are the same as in Example 3.

[0189] Experimental results showed that: carbon soot suppression rate was 60%, CO emission reduction rate was 40%, and NO emission reduction rate was 40%. x Removal rate 51%, UHCs removal rate 35%.

[0190] Compare with Example 7

[0191] Set up a metal cage 2 with a load LSCF, turn on the sound wave, and other conditions are the same as in Example 3.

[0192] Experimental results showed that: carbon soot suppression rate was 64%, CO emission reduction rate was 69%, and NO emission reduction rate was 69%. x Removal rate 50%, UHCs removal rate 70%.

[0193] Compare with Example 8

[0194] Set up a metal cage 2 with a load of Pt-Cu-LSCF, turn off the sound waves, and other conditions are the same as in Example 3.

[0195] Experimental results showed that: carbon soot suppression rate was 80%, CO emission reduction rate was 85%, and NO emission reduction rate was 80%. x Removal rate 75%, UHCs removal rate 80%.

[0196] As can be seen from the comparison of Example 3 and Control Examples 4, 5, 6, 7, and 8, Pt has a certain effect on carbon soot and UHCs, but its effect on NO is limited. x Insufficient inhibition indicates that a single metal catalyst is insufficient for the synergistic control of multiple pollutants. Cu's effect on NO... x It has some selective reduction ability, but its effect on inhibiting soot and CO is poor, and its function is limited. LSCF has a better oxidation effect on CO and UHCs, but its effect on soot and NO is limited. x The inhibition capacity is limited. Although the catalyst has some effect when there is no sound wave, the overall inhibition rate is significantly lower than when there is a sound wave, indicating that sound waves play an important role in promoting mass transfer and self-cleaning.

[0197] Compare with Example 9

[0198] Adjust the sound wave frequency to less than 50Hz and 30Hz, and other conditions are the same as in Example 3.

[0199] Experimental results showed that: carbon soot suppression rate was 60%, CO emission reduction rate was 65%, and NO emission reduction rate was 60%. x Removal rate 55%, UHCs removal rate 58%.

[0200] Compare with Example 10

[0201] Adjust the sound wave frequency to be greater than 300Hz and 500Hz, and other conditions are the same as in Example 3.

[0202] Experimental results showed that: carbon soot suppression rate was 65%, CO emission reduction rate was 68%, and NO emission reduction rate was 65%. x Removal rate 62%, UHCs removal rate 64%.

[0203] As can be seen from Comparative Examples 3 and 9 and 10, when the acoustic frequency is too low, the pulsation intensity is insufficient, the mass transfer and self-cleaning effects are weakened, and the suppression efficiency is significantly reduced. When the acoustic frequency is too high, it causes instability of flame 1 and excessive shearing of the gas flow on the catalyst surface, resulting in a decrease in suppression efficiency.

[0204] Compare with Example 11

[0205] Other conditions are the same as in Example 3, and the system runs continuously for 100 hours.

[0206] Initial performance: NO x Emission reduction rate 99%, CO emission reduction rate 99%, soot suppression rate 99%, UHCs removal rate 99%.

[0207] After running for 50 hours: NO x Emission reduction rate 98.7%, CO emission reduction rate 98.8%, soot suppression rate 98.6%, UHCs removal rate 98.6%.

[0208] After running for 100 hours: NO x Emission reduction rate 98.4%, CO emission reduction rate 98.6%, soot suppression rate 98.2%, UHCs removal rate 98.3%.

[0209] After shutdown, the catalytic filter element was inspected and found to have no obvious carbon deposits or blockages on the surface, and its structure was intact.

[0210] It is evident that the combination of the "online self-cleaning" effect of sound waves and the stability of the catalyst achieves excellent long-term operating performance.

[0211] As can be seen, this invention achieves efficient and synergistic control of multiple pollutants during ammonia fuel combustion through a three-field coupling of "metal cage 2 support - composite catalyst - acoustic excitation". The results of examples and controls show that: the composite catalyst is the core for achieving simultaneous purification of multiple pollutants; acoustic waves significantly improve suppression efficiency and long-term stability by enhancing mass transfer and self-cleaning effects; the metal cage 2 structure provides a stable support for the catalyst while maintaining flame 1 stability; the system exhibits good adaptability to different ammonia / acetylene ratios. This method achieves efficient pollutant suppression while possessing good engineering applicability and stability, providing a feasible technical path for the clean utilization of ammonia fuel.

[0212] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A method for clean combustion of ammonia fuel, characterized in that, The method is achieved through the following combustion device: The nozzle (4) is connected to the fuel supply pipeline and delivers ammonia fuel, which is then ignited to form a diffuse flame (1). The metal cage (2) is a cylindrical hollow tubular structure with openings at both ends. The side circumferential surface is a grid structure. It is suspended around the nozzle (4) in the flame and smoke channel. The nozzle (4) passes through the lower opening of the metal cage (2). The metal cage (2) is placed close to the outermost edge of the diffused flame. The lifting bracket (5) includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod by a connecting clip with orthogonally arranged locking screws and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the metal cage (2). The lifting bracket (5) is used to adjust the height of the metal cage (2). A loudspeaker (3) is positioned at the horizontal side of the metal cage (2) to apply sound waves at a frequency of 50-300Hz to the metal cage. The surface of the metal cage (2) is loaded with a composite catalyst; The method is as follows: ammonia fuel is passed through a vertically upward nozzle (4) and ignited to form a stable diffusion flame (1); the height of the metal cage (2) is adjusted by the lifting bracket (5), the loudspeaker (3) is activated, and sound waves of a specific frequency are applied to the metal cage; through the combined effect of enhanced mass transfer by acoustic pulsation and catalytic oxidation on the catalyst surface, efficient suppression of combustion pollutants is achieved.

2. The clean combustion method for ammonia fuel according to claim 1, characterized in that, The metal wire mesh of the metal cage (2) is made of iron, nickel-based alloy or copper material, with a mesh size of 20-100 mesh and a wire diameter of 0.2-0.6 mm.

3. The clean combustion method for ammonia fuel according to claim 1, characterized in that, The distance between the loudspeaker (3) and the flame is 100-300mm.

4. The clean combustion method for ammonia fuel according to claim 1, characterized in that, The metal cage (2) is positioned at a distance of 1-10 mm from the outermost edge of the flame.

5. The clean combustion method for ammonia fuel according to claim 1, characterized in that, The upper edge of the metal cage (2) extends 20-60 mm from the nozzle.

6. The clean combustion method for ammonia fuel according to claim 1, 2, 3, 4, or 5, characterized in that, The composite catalyst is platinum (Pt), copper (Cu), lanthanum (Lanthanum), strontium (Sr), cobalt (Co), iron (Fe). 0.8 Sr 0.2 Co 0.8 Fe 0.2 O3, Pt-Cu-LSCF; its preparation method is as follows: Weigh the corresponding nitrates according to the La:Sr:Co:Fe:Cu molar ratio of 0.8:0.2:0.8:0.2:0.1, dissolve them in deionized water, add citric acid of 10% of the total molar amount of metal ions, slowly add 10wt% dilute nitric acid, stir until a uniform and stable sol is formed, then add chloroplatinic acid solution of the required Pt loading amount, which is 0.4 wt% of the total loaded catalyst, and stir evenly to obtain the composite sol.

7. The clean combustion method for ammonia fuel according to claim 1, characterized in that, The steps for attaching the composite catalyst to the metal cage (2) are as follows: Step 1: Cut and wind the metal wire mesh into a metal cage (2) of the required size and shape, and then place it in acetone, anhydrous ethanol, 10wt% dilute nitric acid solution and deionized water for ultrasonic cleaning in sequence. After drying, put it into a muffle furnace for high-temperature pre-oxidation at 950℃, and then cool it with the furnace. Step 2: Immerse the pre-oxidized metal cage from Step 1 into the composite sol obtained in claim 6. After full immersion and adsorption, pull it out at a uniform speed. Repeat the immersion and pulling operation three times, and blow away the excess sol with nitrogen. Step 3: After drying the metal cage impregnated with sol in Step 2, heat it to 650°C in air atmosphere and calcine it for 4 hours. After natural cooling, the metal cage loaded with composite catalyst (2) is obtained. Step 4: The metal cage with composite catalyst obtained in Step 3 is activated by reducing the metal cage (2) obtained in Step 3 at 400°C for 2 hours in a hydrogen atmosphere (H2) to activate surface oxygen vacancies; then it is oxidized and stabilized in air at 500°C for 2 hours to obtain a metal cage (2) with a stable catalyst coating.

8. The clean combustion method for ammonia fuel according to claim 7, characterized in that, The method described above can suppress pollutants generated by ammonia fuel combustion by up to 99%, and the suppression effect is long-lasting and stable.

Images