Clean combustion method of biomass fuel

Abstract

The invention discloses a clean combustion method of biomass fuel, which is characterized in that a Ni-Co-Ce-Zn-O / Al2O3 quaternary gradient structured catalyst is designed and prepared for the first time, and abundant oxygen vacancies and redox cycle networks are constructed through multi-metal component atomic-scale compounding; a'porous carrier-active layer-surface modification layer 'gradient configuration is adopted, and catalytic activity, adhesive strength and inactivation resistance are synergistically regulated and controlled on a nano-micron scale. A special sol-gel and segmented coating process is combined, the catalyst forms a uniform and firm active coating with a high specific surface area on the surface of the metal wire mesh cage, and excellent structural stability and catalytic durability are still kept under the conditions of high temperature, vibration and electric field-sound field coupling. According to the catalyst system, the soot ignition activity and the low-temperature conversion efficiency of CO and nitrogen oxide are remarkably improved, intrinsic synergy with an electric field and a sound field is achieved through the dielectric property and the surface dynamic response behavior of the catalyst system, and a catalysis-electricity-sound ternary coupling enhanced reaction microenvironment is formed.

Description

Technical Field

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

[0002] Biomass fuel, as an ancient yet emerging form of energy, is increasingly becoming an important component of global energy transition and sustainable development strategies. It originates from renewable organic matter in nature, such as crop residues, forestry waste, energy crops, and some organic household waste, and is processed into solid, liquid, or gaseous fuel forms.

[0003] From a historical perspective, humans have used biomass for heating and cooking for thousands of years. In the contemporary context, biomass fuel has been given new significance: it is not only an important alternative to fossil fuels, but also connects several key sectors such as agriculture, forestry, environmental protection, and rural development. With the global trend of jointly addressing climate change and pursuing energy security and a low-carbon future, the value of biomass fuel is becoming increasingly prominent.

[0004] While recognizing the aforementioned potential of biomass fuels, we must also acknowledge the environmental challenges that accompany their direct combustion. Similar to fossil fuels, biomass, under non-ideal combustion conditions, produces a certain amount of gaseous pollutants, mainly including visible soot, colorless carbon monoxide (CO), and nitrogen oxides (NOx).

[0005] The formation of these pollutants not only reduces energy efficiency but also poses potential impacts on ambient air quality and public health. Particulate matter can affect local visibility and be inhaled; carbon monoxide is a toxic gas; and nitrogen oxides are associated with photochemical smog and acid rain. This contradiction highlights a core issue in the biomass fuel sector: how to fully utilize its carbon-neutral advantages and obtain green energy while minimizing associated pollution during combustion.

[0006] Therefore, exploring and discovering a method or pathway to effectively suppress the formation of the aforementioned gaseous pollutants becomes crucial. Such a breakthrough would not only significantly improve the cleanliness of biomass fuels, making their environmental friendliness truly deserved, but also bring about many positive impacts. Summary of the Invention

[0007] This invention addresses the various shortcomings of existing technologies by providing a clean combustion method for biomass fuels, which is used to suppress the generation of soot and various gaseous pollutants during the combustion of biomass fuels.

[0008] This invention is achieved through the following technical solution:

[0009] This invention discloses a clean combustion method for biomass fuel, which is implemented using the following burner:

[0010] The burner body is a tubular structure open at both ends;

[0011] Combustion support device, a wire mesh for fixing fuel located inside the burner body, used to hold biomass fuel;

[0012] The metal electrode mesh is a hollow cylindrical tubular structure with open ends and a mesh structure on the side circumference, and is placed around the biomass fuel pellets.

[0013] An acoustic excitation device is installed at the bottom of the burner body, with a gap of 10–40 mm between it and the bottom of the burner body, and is used to apply a specific frequency sound wave of 100–300 Hz to the inside of the burner; a catalytic metal wire cage is suspended above the biomass fuel and in the flame and flue gas passage.

[0014] The lifting platform includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to a catalytic metal wire cage. The lifting platform is used to adjust the height of the catalytic metal wire cage.

[0015] A DC high-voltage power supply with two electrodes connected to a metal electrode mesh and a catalytic metal wire cage, respectively; the surface of the catalytic metal wire cage is loaded with a gradient structured composite metal oxide catalyst; the power supply can provide 1000–5000V DC or pulse voltage, and the electrode spacing is 100–200mm.

[0016] The method is as follows: the treated biomass fuel is placed on the combustion support device and ignited to form a stable diffusion flame in the burner body; the height of the catalytic metal wire cage is adjusted by the lifting mechanism, the acoustic excitation device is activated to apply a specific frequency sound wave that matches the acoustic resonance frequency of the burner body, and the DC high voltage power supply is turned on to apply voltage to the catalytic metal wire cage; through the combined effects of acoustic pulsation to enhance mass transfer, catalytic oxidation on the catalyst surface, and the metal wire cage, efficient suppression of soot, carbon monoxide, and nitrogen oxides is achieved.

[0017] As a further improvement, the gradient-structured composite metal oxide catalyst of the present invention is a nickel-cobalt-cerium-zinc quaternary composite oxide, which is prepared by a sol-gel and segmented coating method and then activated to form a stable coating. The preparation method is as follows:

[0018] Step 1: Weigh nickel nitrate, cobalt nitrate, cerium nitrate, and zinc nitrate according to the metal molar ratio Ni:Co:Ce:Zn=3:2:4:1; dissolve them in deionized water, and add citric acid with a metal ion:citric acid ratio of 1:1.5 as a complexing agent;

[0019] Step 2: Add pseudoboehmite AlOOH powder, the amount of which is 20wt% of the total theoretical oxide mass of the final catalyst, and stir until completely dissolved;

[0020] Step 3: Adjust the pH of the above solution to 3-4, stir continuously in an 80℃ water bath for 4 hours to form a uniform and stable dark green sol; add 5% polyvinyl alcohol (PVA) as a binder and pore-forming agent to form a catalytic sol.

[0021] As a further improvement, the method for attaching catalyst to the catalytic metal wire cage of the present invention is as follows:

[0022] Step 1: Immerse the pretreated catalytic metal wire cage in pure Al2O3 sol and coat it by lifting; dry at 100℃ for 10 minutes and calcine at 500℃ for 1 hour to form a porous transition layer;

[0023] Step 2: Immerse the catalytic metal wire cage that forms the porous transition layer into the catalytic sol, and coat it by lifting; after drying at 100°C, heat it to 700°C at 2°C / min and calcine it for 3 hours to form a spinel-fluorite composite oxide active layer.

[0024] Step 3: Prepare a Ce(NO3)3 and Zn(NO3)2 solution with a Ce:Zn ratio of 3:1, and spray it evenly onto the surface of the spinel-fluorite composite oxide active layer using a spray method; heat-treat at 500℃ for 2 hours to form a Ce-Zn-rich nano-modified layer on the surface.

[0025] Step 4: Activation treatment of the Ce-Zn-rich nano-modified layer on the surface: reduction at 400℃ for 2 hours in H2 atmosphere to activate surface oxygen vacancies; then oxidized and stabilized in air at 500℃ for 2 hours to obtain a stable gradient structured catalyst coating.

[0026] As a further improvement, the catalytic metal wire cage of the present invention is made of iron, nickel-based alloy or copper material, with a mesh structure on the top and side circumferential surfaces, and an opening at the bottom. The mesh size is 20-80 mesh, and the diameter of the metal wire is 0.15-0.35 mm.

[0027] As a further improvement, the acoustic excitation device of the present invention applies a sound wave frequency that matches the acoustic resonance frequency of the burner body.

[0028] As a further improvement, the method described in this invention has an efficiency of over 99% in suppressing soot produced by biomass fuel combustion, and an efficiency of over 99% in suppressing CO and nitrogen oxides, and has the characteristics of rapid response and long-term stability.

[0029] As a further improvement, the biomass fuel described in this invention is redwood pellets, and the acoustic excitation device is a loudspeaker.

[0030] As a further improvement, the movable connecting device of the present invention is a connecting clip with orthogonally arranged locking screws.

[0031] The beneficial effects of this invention are as follows:

[0032] 1. A novel multi-physics field synergistic regulation mechanism of "catalysis-electric field-acoustic field" was constructed, realizing in-situ efficient catalytic oxidation of pollutants. This invention is the first to deeply integrate a composite non-precious metal catalyst, a high-voltage electrostatic field, and low-frequency acoustic excitation, forming a spatiotemporally coupled multi-field synergistic environment within the combustion chamber. The catalyst provides highly active oxidation sites, the electric field drives the directional migration of soot particles and their enrichment at the catalytic interface, and the acoustic field significantly enhances gas-solid mass transfer and reaction kinetics. This synergistic mechanism breaks through the bottleneck of traditional single technologies, achieving simultaneous and efficient removal of multiple pollutants such as soot, CO, and nitrogen oxides at the combustion source, with the system response time shortened to the second level.

[0033] 2. This invention is the first to design and prepare a Ni-Co-Ce-Zn-O / Al2O3 quaternary gradient structured catalyst. This catalyst constructs a rich network of oxygen vacancies and redox cycles through atomic-level composite of multiple metal components. Employing a gradient configuration of "porous support-active layer-surface modification layer," it synergistically regulates catalytic activity, adhesion strength, and resistance to deactivation at the nano- to micro-scale. Combined with a specialized sol-gel and segmented coating process, the catalyst forms a uniform, robust, and high-specific-surface-area active coating on the surface of a metal wire mesh cage, maintaining excellent structural stability and catalytic persistence even under high temperature (800℃), vibration, and electric-acoustic field coupling conditions. This catalyst system not only significantly improves the soot ignition activity and the low-temperature conversion efficiency of CO and nitrogen oxides, but also achieves intrinsic synergy with the electric and acoustic fields through its dielectric properties and surface dynamic response behavior, forming a strengthened reaction microenvironment with "catalysis-electro-acoustic" ternary coupling.

[0034] 3. The cylindrical catalytic grid suppression structure proposed in this invention combines the functions of catalyst support, electrode, and flow control. Its bottom opening design ensures flame stability and unobstructed flow. Combined with a height-adjustable mechanism and a programmable electro-acoustic excitation module, the system can flexibly adapt to different fuel and load conditions, achieving dynamic optimization control. The overall device has a compact structure and is easy to integrate.

[0035] 4. This method has an efficiency of over 99% in suppressing soot produced by biomass fuel combustion, and an efficiency of over 99% in suppressing CO and nitrogen oxides. The response time is shortened to the second level, and the suppression effect is long-lasting and stable. Attached Figure Description

[0036] Figure 1This is a schematic diagram of the burner used in this invention, wherein 1 is an acoustic excitation device, 2 is a wire mesh for fixing fuel, 3 is the burner body, 4 is a metal electrode mesh, 5 is a catalytic metal wire cage, 6 is a DC high-voltage power supply, and 7 is a lifting platform. Detailed Implementation

[0037] This invention discloses a clean combustion method for biomass fuel, which is implemented using the following burner:

[0038] The burner body 3 is a tubular structure with openings at both ends;

[0039] The combustion support device is a wire mesh for fixing fuel located inside the burner body 3, used to hold biomass fuel.

[0040] The metal electrode mesh 4 is a hollow cylindrical tubular structure with openings at both ends and a mesh structure on the side circumference, and is placed around the biomass fuel pellets.

[0041] Acoustic excitation device 1 is located at the bottom of burner body 3, with a gap of 10–40 mm between it and the bottom of burner body 3, and is used to apply a specific frequency sound wave of 100–300 Hz to the inside of the burner; catalytic metal wire cage 5 is suspended above the biomass fuel and in the flame and flue gas passage.

[0042] The lifting platform 7 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5.

[0043] The DC high voltage power supply 6 has two electrodes connected to a metal electrode mesh 4 and a catalytic metal wire cage 5, respectively. The surface of the catalytic metal wire cage 5 is loaded with a gradient structured composite metal oxide catalyst. The power supply can provide a DC or pulse voltage of 1000–5000V, and the electrode spacing is 100–200mm.

[0044] The method is as follows: the treated biomass fuel is placed on the combustion support device and ignited, forming a stable diffusion flame in the burner body 3; the height of the catalytic metal wire cage 5 is adjusted by the lifting mechanism, the acoustic excitation device 1 is activated to apply a specific frequency sound wave that matches the acoustic resonance frequency of the burner body 3, and the DC high voltage power supply 6 is turned on to apply voltage to the catalytic metal wire cage 5; through the combined effects of acoustic pulsation to enhance mass transfer, catalyst surface catalytic oxidation and the metal wire cage, the efficient suppression of soot, carbon monoxide and nitrogen oxides is achieved.

[0045] The gradient-structured composite metal oxide catalyst is a nickel-cobalt-cerium-zinc quaternary composite oxide, prepared by a sol-gel and segmented coating method, and then activated to form a stable coating. The preparation method is as follows:

[0046] Step 1: Weigh nickel nitrate, cobalt nitrate, cerium nitrate, and zinc nitrate according to the metal molar ratio Ni:Co:Ce:Zn=3:2:4:1; dissolve them in deionized water, and add citric acid with a metal ion:citric acid ratio of 1:1.5 as a complexing agent;

[0047] Step 2: Add pseudoboehmite AlOOH powder, the amount of which is 20wt% of the total theoretical oxide mass of the final catalyst, and stir until completely dissolved;

[0048] Step 3: Adjust the pH of the above solution to 3-4, stir continuously in an 80℃ water bath for 4 hours to form a uniform and stable dark green sol; add 5% polyvinyl alcohol (PVA) as a binder and pore-forming agent to form a catalytic sol.

[0049] The method for attaching the catalyst to the catalytic wire cage 5 is as follows:

[0050] Step 1: Immerse the pretreated catalytic metal wire cage 5 in pure Al2O3 sol and coat it by lifting; dry at 100℃ for 10 minutes and calcine at 500℃ for 1 hour to form a porous transition layer;

[0051] Step 2: Immerse the catalytic metal wire cage 5, which forms the porous transition layer, into the catalytic sol and coat it by lifting; after drying at 100°C, heat it to 700°C at 2°C / min and calcine it for 3 hours to form a spinel-fluorite composite oxide active layer.

[0052] Step 3: Prepare a Ce(NO3)3 and Zn(NO3)2 solution with a Ce:Zn ratio of 3:1, and spray it evenly onto the surface of the spinel-fluorite composite oxide active layer using a spray method; heat-treat at 500℃ for 2 hours to form a Ce-Zn-rich nano-modified layer on the surface.

[0053] Step 4: Activation treatment of the Ce-Zn-rich nano-modified layer on the surface: reduction at 400℃ for 2 hours in H2 atmosphere to activate surface oxygen vacancies; then oxidized and stabilized in air at 500℃ for 2 hours to obtain a stable gradient structured catalyst coating.

[0054] The catalytic wire cage 5 is made of iron, nickel-based alloy, or copper. Its top and side circumferential surfaces have a mesh structure, while the bottom is open. The mesh size is 20-80 mesh, and the wire diameter is 0.15-0.35 mm. The acoustic excitation device 1 applies a sound wave frequency that matches the acoustic resonance frequency of the burner body 3.

[0055] The method has an efficiency of over 99% in suppressing soot produced by biomass fuel combustion, and an efficiency of over 99% in suppressing CO and nitrogen oxides. It also features rapid response and long-term stability.

[0056] The biomass fuel is redwood pellets, and the acoustic excitation device 1 is a loudspeaker. The movable connection device is a connecting clamp with orthogonally arranged locking screws. The movable connection device is a connecting clamp with orthogonally arranged locking screws, including a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod by the connecting clamp through the orthogonally arranged locking screws and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5. The connecting clamp is vertically connected to the longitudinal rod and transversely connected to the transverse rod. The connecting clamp has locking screws that can be tightened and loosened to adjust the movement of the transverse rod fixed by the connecting clamp on the longitudinal rod.

[0057] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of the present invention is not limited to the embodiments.

[0058] Example 1

[0059] This embodiment provides a clean combustion method for biomass fuel. Figure 1 This is a schematic diagram of the structure of the burner used in this invention; the burner body 3 is a tubular structure with open ends, and its inner diameter is 60mm and its length is 1.2m, which is a high-temperature resistant quartz tube.

[0060] The combustion support device 2, located inside the burner body 3, is a wire mesh 2 for fixing fuel and for placing biomass fuel;

[0061] The metal electrode mesh 4 is a cylindrical hollow tubular structure with openings at both ends, and the side circumferential surface is a mesh structure, which is set around the biomass fuel particles.

[0062] Acoustic excitation device 1 is located at the bottom of the burner body 3, with a 10mm gap between it and the bottom of the burner body 3, and is used to apply a specific frequency sound wave of 185Hz to the inside of the burner; catalytic metal wire cage 5 has a metal wire diameter of 0.15mm and a mesh count of 20; it is suspended above the biomass fuel and in the flame and flue gas passage of the catalytic metal wire cage 5.

[0063] The lifting platform 7 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5.

[0064] A DC high-voltage power supply 6 has two electrodes connected to a metal electrode mesh 4 and a catalytic metal wire cage 5, respectively; the surface of the catalytic metal wire cage 5 is loaded with a gradient structured composite metal oxide catalyst; the power supply provides a DC or pulse voltage of 1000V, and the electrode spacing is 100mm.

[0065] Implementation method:

[0066] 1) Ignite the redwood particles and adjust the lifting mechanism 7 so that the catalytic metal wire cage 5 is 100mm away from the bottom metal electrode mesh 4.

[0067] 2) Start speaker 1 and start DC high voltage power supply 6.

[0068] 3) The flame is visibly stable and the black smoke has disappeared. Testing showed a carbon soot suppression efficiency of 99.2%, a CO emission reduction rate of 99%, and a nitrogen oxide removal rate of 92%.

[0069] Example 2

[0070] This embodiment provides a clean combustion method for biomass fuel. Figure 1 This is a schematic diagram of the structure of the burner used in this invention; the burner body 3 is a tubular structure with open ends, and its inner diameter is 60mm and its length is 1.2m, which is a high-temperature resistant quartz tube.

[0071] The combustion support device 2, located inside the burner body 3, is a wire mesh 2 for fixing fuel and for placing biomass fuel;

[0072] The metal electrode mesh 4 is a cylindrical hollow tubular structure with openings at both ends, and the side circumferential surface is a mesh structure, which is set around the biomass fuel particles.

[0073] Acoustic excitation device 1 is located at the bottom of the burner body 3, with a 10mm gap between it and the bottom of the burner body 3, and is used to apply a specific frequency sound wave of 185Hz to the inside of the burner; catalytic metal wire cage 5 has a metal wire diameter of 0.25mm and a mesh count of 40; it is suspended above the biomass fuel and in the flame and flue gas passage of the catalytic metal wire cage 5.

[0074] The lifting platform 7 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5.

[0075] A DC high-voltage power supply 6 has two electrodes connected to a metal electrode mesh 4 and a catalytic metal wire cage 5, respectively; the surface of the catalytic metal wire cage 5 is loaded with a gradient structured composite metal oxide catalyst; the power supply provides a DC or pulse voltage of 3000V, and the electrode spacing is 150mm.

[0076] Implementation method:

[0077] 1) Ignite the redwood particles and adjust the lifting mechanism 7 so that the catalytic metal wire cage 5 is 150mm away from the bottom metal electrode mesh 4.

[0078] 2) Start speaker 1 and start DC high voltage power supply 6.

[0079] 3) The flame is visibly stable and the black smoke has disappeared. Testing showed that the carbon soot suppression efficiency reached 99.8%, the CO emission reduction rate was 99.3%, and the nitrogen oxide removal rate was 97.5%.

[0080] Example 3

[0081] This embodiment provides a clean combustion method for biomass fuel. Figure 1 This is a schematic diagram of the structure of the burner used in this invention; the burner body 3 is a tubular structure with open ends, and its inner diameter is 60mm and its length is 1.2m, which is a high-temperature resistant quartz tube.

[0082] The combustion support device 2, located inside the burner body 3, is a wire mesh 2 for fixing fuel and for placing biomass fuel;

[0083] The metal electrode mesh 4 is a cylindrical hollow tubular structure with openings at both ends, and the side circumferential surface is a mesh structure, which is set around the biomass fuel particles.

[0084] An acoustic excitation device 1 is located at the bottom of the burner body 3, with a 10mm gap between it and the bottom of the burner body 3, and is used to apply a specific frequency sound wave of 185Hz to the inside of the burner; a catalytic metal wire cage 5 has a wire diameter of 0.35mm and a mesh count of 80; it is suspended above the biomass fuel and in the flame and flue gas passage.

[0085] The lifting platform 7 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5.

[0086] A DC high-voltage power supply 6 has two electrodes connected to a metal electrode mesh 4 and a catalytic metal wire cage 5, respectively; the surface of the catalytic metal wire cage 5 is loaded with a gradient structured composite metal oxide catalyst; the power supply provides a DC or pulse voltage of 5000V, and the electrode spacing is 200mm.

[0087] Implementation method:

[0088] 1) Ignite the redwood particles and adjust the lifting mechanism 7 so that the catalytic metal wire cage 5 is 200mm away from the bottom metal electrode mesh 4.

[0089] 2) Start speaker 1 and start DC high voltage power supply 6.

[0090] 3) The flame is visibly stable and the black smoke has disappeared. Testing showed a carbon soot suppression efficiency of 99.1%, a CO emission reduction rate of 99%, and a nitrogen oxide removal rate of 93%.

[0091] Example 4

[0092] This embodiment provides a clean combustion method for biomass fuel. Figure 1 This is a schematic diagram of the structure of the burner used in this invention; the burner body 3 is a tubular structure with open ends, and its inner diameter is 60mm and its length is 1.2m, which is a high-temperature resistant quartz tube.

[0093] The combustion support device 2, located inside the burner body 3, is a wire mesh 2 for fixing fuel and for placing biomass fuel;

[0094] The metal electrode mesh 4 is a cylindrical hollow tubular structure with openings at both ends, and the side circumferential surface is a mesh structure, which is set around the biomass fuel particles.

[0095] An acoustic excitation device 1 is located at the bottom of the burner body 3, with a 10mm gap between it and the bottom of the burner body 3, and is used to apply a specific frequency sound wave of 210Hz to the inside of the burner; a catalytic metal wire cage 5 has a wire diameter of 0.15mm and a mesh count of 20; it is suspended above the biomass fuel and in the flame and flue gas passage.

[0096] The lifting platform 7 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5.

[0097] A DC high-voltage power supply 6 has two electrodes connected to a metal electrode mesh 4 and a catalytic metal wire cage 5, respectively; the surface of the catalytic metal wire cage 5 is loaded with a gradient structured composite metal oxide catalyst; the power supply provides a DC or pulse voltage of 1000V, and the electrode spacing is 100mm.

[0098] Implementation method:

[0099] 1) Ignite the redwood particles and adjust the lifting mechanism 7 so that the catalytic metal wire cage 5 is 100mm away from the bottom metal electrode mesh 4.

[0100] 2) Start speaker 1 and start DC high voltage power supply 6.

[0101] 3) The flame is visibly stable and the black smoke has disappeared. Testing showed that the carbon soot suppression efficiency reached 99.5%, the CO emission reduction rate was 99.3%, and the nitrogen oxide removal rate was 91.5%.

[0102] Example 5

[0103] This embodiment provides a clean combustion method for biomass fuel. Figure 1 This is a schematic diagram of the structure of the burner used in this invention; the burner body 3 is a tubular structure with open ends, and its inner diameter is 60mm and its length is 1.2m, which is a high-temperature resistant quartz tube.

[0104] The combustion support device 2, located inside the burner body 3, is a wire mesh 2 for fixing fuel and for placing biomass fuel;

[0105] The metal electrode mesh 4 is a cylindrical hollow tubular structure with openings at both ends, and the side circumferential surface is a mesh structure, which is set around the biomass fuel particles.

[0106] An acoustic excitation device 1 is located at the bottom of the burner body 3, with a 10mm gap between it and the bottom of the burner body 3, and is used to apply a specific frequency sound wave of 210Hz to the inside of the burner; a catalytic metal wire cage 5 has a wire diameter of 0.25mm and a mesh count of 40; it is suspended above the biomass fuel and in the flame and flue gas passage.

[0107] The lifting platform 7 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5.

[0108] A DC high-voltage power supply 6 has two electrodes connected to a metal electrode mesh 4 and a catalytic metal wire cage 5, respectively; the surface of the catalytic metal wire cage 5 is loaded with a gradient structured composite metal oxide catalyst; the power supply provides a DC or pulse voltage of 3000V, and the electrode spacing is 150mm.

[0109] Implementation method:

[0110] 1) Ignite the redwood particles and adjust the lifting mechanism 7 so that the catalytic metal wire cage 5 is 150mm away from the bottom metal electrode mesh 4.

[0111] 2) Start speaker 1 and start DC high voltage power supply 6.

[0112] 3) The flame is visibly stable and the black smoke has disappeared. Testing showed that the carbon soot suppression efficiency reached 99.9%, the CO emission reduction rate was 99.8%, and the nitrogen oxide removal rate was 99.1%.

[0113] Example 6

[0114] This embodiment provides a clean combustion method for biomass fuel. Figure 1 This is a schematic diagram of the structure of the burner used in this invention; the burner body 3 is a tubular structure with open ends, and its inner diameter is 60mm and its length is 1.2m, which is a high-temperature resistant quartz tube.

[0115] The combustion support device 2, located inside the burner body 3, is a wire mesh 2 for fixing fuel and for placing biomass fuel;

[0116] The metal electrode mesh 4 is a cylindrical hollow tubular structure with openings at both ends, and the side circumferential surface is a mesh structure, which is set around the biomass fuel particles.

[0117] Acoustic excitation device 1 is located at the bottom of the burner body 3, with a 10mm gap between it and the bottom of the burner body 3, and is used to apply a specific frequency sound wave of 210Hz to the inside of the burner; catalytic metal wire cage 5 has a wire diameter of 0.35mm and a mesh count of 80; it is suspended above the biomass fuel and in the flame and flue gas passage.

[0118] The lifting platform 7 includes a longitudinal rod and a transverse rod that is movably connected to the longitudinal rod via a movable connecting device and moves up and down along the longitudinal rod. The end of the transverse rod is connected to the catalytic metal wire cage 5. The lifting platform 7 is used to adjust the height of the catalytic metal wire cage 5.

[0119] A DC high-voltage power supply 6 has two electrodes connected to a metal electrode mesh 4 and a catalytic metal wire cage 5, respectively; the surface of the catalytic metal wire cage 5 is loaded with a gradient structured composite metal oxide catalyst; the power supply provides a DC or pulse voltage of 5000V, and the electrode spacing is 200mm.

[0120] Implementation method:

[0121] 1) Ignite the redwood particles and adjust the lifting mechanism 7 so that the catalytic metal wire cage 5 is 200mm away from the bottom metal electrode mesh 4.

[0122] 2) Start speaker 1 and start DC high voltage power supply 6.

[0123] 3) The flame is visibly stable and the black smoke has disappeared. Testing showed that the carbon soot suppression efficiency reached 99.6%, the CO emission reduction rate was 98.8%, and the nitrogen oxide removal rate was 92.6%.

[0124] Compare with Example 1

[0125] Compared to Example 5, only the acoustic excitation device 1 with a frequency of 210Hz was added; everything else remained the same. Testing showed that the carbon soot suppression efficiency reached 45%, the CO emission reduction rate was 40%, and the nitrogen oxide removal rate was 32%.

[0126] Compare with Example 2

[0127] Compared to Example 5, the only difference was that the catalyst was attached to the catalytic wire cage 5; everything else remained the same. Testing showed that the soot suppression efficiency reached 35%, the CO emission reduction rate was 30%, and the nitrogen oxide removal rate was 23%.

[0128] Compare with Example 3

[0129] Compared to Example 5, only an electric field with a voltage of 3000V was added to the flame; everything else remained the same. Testing showed a carbon soot suppression efficiency of 38%, a CO emission reduction rate of 33%, and a nitrogen oxide removal rate of 25%.

[0130] Compare with Example 4

[0131] Compared to Example 5, only sound waves and an electric field were applied, with a frequency of 210Hz and an electric field voltage of 3000V; everything else remained the same. Testing showed that the carbon soot suppression efficiency reached 55%, CO emission reduction rate was 48%, and nitrogen oxide removal rate was 40%.

[0132] Compare with Example 5

[0133] Compared to Example 5, only a catalyst and an electric field were added; the voltage of the sound field was 3000V, and everything else remained the same. Testing showed that the carbon soot suppression efficiency reached 43%, CO emission reduction rate was 38%, and nitrogen oxide removal rate was 32%.

[0134] Compare with Example 6

[0135] Compared to Example 5, only a catalyst and sound waves were added, with the sound wave frequency being 210Hz; everything else remained the same. Testing showed that the soot suppression efficiency reached 46%, CO emission reduction rate was 41%, and nitrogen oxide removal rate was 36%.

[0136] As can be seen, compared with Example 5, Comparative Examples 1-6 only applied a single longitudinal sound wave, a longitudinal electric field, or added a compound catalyst for catalytic oxidation, or used two combinations to control pollutant gases, without achieving the synergistic effect of the three, resulting in poor soot suppression effect. Both single and dual-element technology combinations have shortcomings in the "mass transfer-oxidation-migration" process, and cannot simultaneously achieve efficient enrichment, rapid mass transfer and complete oxidation of pollutants in the combustion chamber, thus failing to achieve low-pollution clean combustion.

[0137] Compare with Example 7

[0138] Compared to Example 5, the frequency of the sound wave was adjusted to a non-resonant frequency; everything else remained the same. Testing showed a carbon soot suppression efficiency of 58%, a CO emission reduction rate of 52%, and a nitrogen oxide removal rate of 48%.

[0139] As can be seen, the sound waves applied in Comparative Example 7, compared to Example 5, are not at their resonant frequency. This non-resonant state causes sound energy to dissipate, failing to support the spatiotemporal order required for the ternary synergy of "sound-electricity-catalysis." Consequently, the system performance degrades to a level close to that of a single technology or a binary combination. This results in poor soot suppression and an inability to achieve low-pollution clean combustion.

[0140] Compare with Example 8

[0141] Compared to Example 5, the method of attaching the catalyst to the catalytic wire cage 5 did not provide an Al2O3 microporous support; all other aspects remained the same. Testing showed that the carbon soot suppression efficiency reached 60%, CO emission reduction rate was 56%, and nitrogen oxide removal rate was 52%.

[0142] As can be seen, Comparative Example 8, compared to Example 5, did not provide a microporous catalyst support. Without a microporous support, the catalyst cannot be effectively integrated with the electric field, acoustic field, and combustion flow field, resulting in insufficient reactant contact, uncontrolled heat management, and poor resistance to deactivation. This leads to low and unstable removal efficiency of gaseous pollutants, resulting in poor soot suppression and the inability to achieve low-pollution clean combustion.

[0143] Compare with Example 9

[0144] Compared to Example 5, the catalyst on the surface of the catalytic wire cage 5 is a ternary composite catalyst, a manganese-cerium-copper composite oxide, while everything else remains the same. Testing showed that the carbon soot suppression efficiency reached 76%, the CO emission reduction rate was 68%, and the nitrogen oxide removal rate was 64%.

[0145] As can be seen, in Comparative Example 9 compared to Example 5, a conventional ternary composite catalyst was used. The active components were unevenly distributed, and at high temperatures, particle agglomeration, phase separation, or active phase sintering easily occurred (e.g., CuO easily agglomerates at >600℃). This resulted in insufficient reactant contact, uncontrolled heat management, and poor resistance to deactivation. The ternary catalyst also had a low dielectric constant and weak polarization response in an electric field, making it difficult to enhance surface adsorption and charge transfer through an electric field. Consequently, the removal efficiency of gaseous pollutants was low and unstable. This led to poor soot suppression and an inability to achieve low-pollution clean combustion.

[0146] 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 biomass fuel, characterized by, The method is realized by the following combustor: The combustor body (3) is a tubular structure with open ends; The combustion carrier (2) is a fixed fuel wire mesh in the combustor body (3) for placing biomass fuel; The metal electrode mesh (4) is a hollow cylindrical tubular structure with open ends, and the side circumferential surface is a grid structure, which is arranged around the biomass fuel particles; The acoustic excitation device (1) is arranged at the bottom of the combustor body (3) and has a gap of 10-40 mm with the bottom of the combustor body (3), which is used to apply a specific frequency acoustic wave of 100-300 Hz to the inside of the combustor; The lifting platform (7) includes a longitudinal rod and a transverse rod movably connected with the longitudinal rod and moving up and down along the longitudinal rod, and the end of the transverse rod is connected with the catalytic wire cage (5), and the lifting platform (7) is used to adjust the height of the catalytic wire cage (5); The direct current high voltage power supply (6) has two electrodes connected with the metal electrode mesh (4) and the catalytic wire cage (5) respectively; the surface of the catalytic wire cage (5) is loaded with a gradient structured composite metal oxide catalyst; the power supply can provide a direct current or pulse voltage of 1000-5000 V, and the electrode spacing is 100-200 mm; The method is as follows: placing the treated biomass fuel on the combustion carrier (2) and igniting to form a stable diffusion flame in the combustor body (3); adjusting the height of the catalytic wire cage (5) through the lifting mechanism, starting the acoustic excitation device (1), applying a specific frequency acoustic wave matching the acoustic resonance frequency of the combustor body (3), and turning on the direct current high voltage power supply (6) to apply voltage on the catalytic wire cage (5); through the combined action of acoustic pulsation, catalyst surface catalytic oxidation and metal wire cage, the efficient suppression of carbon smoke, carbon monoxide and nitrogen oxides is realized.

2. The method of claim 1, wherein the biomass fuel is a wood pellet. The gradient structured composite metal oxide catalyst is a nickel-cobalt-cerium-zinc quaternary composite oxide prepared by sol-gel and segmented coating method, and is activated to form a stable coating, and its preparation method is as follows: Step one: take nickel nitrate, cobalt nitrate, cerium nitrate and zinc nitrate, and weigh according to the metal molar ratio Ni:Co:Ce:Zn=3:2:4:1; dissolve in deionized water, and add citric acid as a complexing agent with a metal ion: citric acid ratio of 1:1.5; Step two: add pseudo-boehmite AlOOH powder, the addition amount is 20wt% of the total theoretical oxide mass of the final catalyst, and stir until completely dissolved; Step three: adjust the pH of the above solution to 3-4, and continuously stir in a 80℃ water bath for 4 hours to form a uniform and stable dark green sol; add 5% polyvinyl alcohol (PVA) as a binder and pore former to form a catalytic sol.

3. The method of claim 1, wherein the biomass fuel is a wood pellet. The method for attaching the catalyst to the catalytic wire cage is as follows: Step one: immerse the pretreated catalytic metal wire cage (5) into pure Al2O3 sol, and draw and coat; dry at 100 DEG C for 10 minutes, and bake at 500 DEG C for 1 hour to form a porous transition layer; Step two: immerse the catalytic metal wire cage (5) with the porous transition layer into catalytic sol, and draw and coat; dry at 100 DEG C, then heat to 700 DEG C at a rate of 2 DEG C / min, and bake for 3 hours to form a spinel-fluorite composite oxide active layer; Step three: prepare a solution of Ce(NO3)3 and Zn(NO3)2 with a Ce:Zn ratio of 3:1, and spray the solution onto the surface of the spinel-fluorite composite oxide active layer by using a spray method; heat treat at 500 DEG C for 2 hours to form a surface Ce-Zn-rich nano-modified layer; Step four: activate the surface Ce-Zn-rich nano-modified layer, reduce in a H2 atmosphere at 400 DEG C for 2 hours to activate the surface oxygen vacancies; then oxidize in air at 500 DEG C for 2 hours to obtain a stable gradient-structured catalyst coating.

4. The method of claim 1 or 2 or 3, wherein, The catalytic metal wire cage (5) is made of iron, nickel-based alloy or copper material, and has a grid structure on the upper surface and side circumferential surface, and an opening on the lower surface; the grid mesh is 20-80 meshes, and the wire diameter is 0.15-0.35 mm.

5. The method of claim 4, wherein the biomass fuel is a wood pellet. The acoustic excitation device (1) applies acoustic waves with a frequency matching the acoustic resonance frequency of the burner body (3).

6. The method of claim 5, wherein the biomass fuel is a wood pellet. The method has an inhibition efficiency of more than 99% on the carbon soot generated by biomass fuel combustion, and an inhibition efficiency of more than 99% on CO and nitrogen oxides, and has the characteristics of fast response and long-term stability.

7. The method of clean combustion of biomass fuel as claimed in claim 1 or 2 or 3 or 5 or 6 wherein, The biomass fuel is redwood particles, and the acoustic excitation device (1) is a loudspeaker.

8. The method of claim 7, wherein the biomass fuel is a wood pellet. The movable connecting device is a connecting clamp with orthogonally arranged locking screws.

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