Biomass gas low-nitrogen combustor

Abstract

This invention discloses a low-NOx biomass gas burner, comprising a pre-combustion chamber and a fuel delivery pipe connected to the pre-combustion chamber. A secondary air duct is formed by installing an outer jacket outside the pre-combustion chamber, with a second cyclone vane at one end. A primary air duct is formed by installing an outer jacket on the outer wall of the pre-combustion chamber, connected to the pre-combustion chamber, and with a first cyclone vane at one end. A catalytic device is installed inside the fuel injection port of the pre-combustion chamber. The beneficial effects of this invention are: the honeycomb-shaped denitrification catalyst installed in the pre-combustion chamber effectively reduces the generation of nitrogen oxides; the use of flue gas premixed combustion technology further effectively reduces nitrogen oxide generation; the honeycomb-shaped denitrification catalyst can also remove / filter dust from the biomass gas, achieving two benefits at once; and a cascaded combustion mode can be formed, eliminating the high-temperature zone of the flame and further reducing the amount of nitrogen oxides generated.

Description

Technical Field

[0001] This invention belongs to the field of boiler combustion technology, specifically relating to a low-NOx biomass combustion burner. Background Technology

[0002] Biomass gas is the only renewable gas that can replace fossil fuels (natural gas and liquefied petroleum gas), and its industrial development is an important path to achieving "carbon peaking and carbon neutrality." Low-NOx combustion technology is the key to breaking through the bottlenecks in the application of biomass gas.

[0003] Existing biomass gasification furnaces generally use single-layer direct-fired combustion technology, commonly known as "direct flame." This burner has a single-layer annular structure, where biomass gas is mixed with air and then ejected for combustion. Because the burner is a single-layer annular structure, the flame ejected is linear, leading to uneven mixing of biomass gas and air. This results in incomplete combustion, low combustion efficiency, and the release of harmful gases, polluting the environment. In existing technologies, biomass gas combustion in current burners still results in high NO levels. x The issue of emissions is that its cleanliness is insufficient, making it unable to replace fossil fuels (such as natural gas) in areas like urban heating, industrial boilers, and residential gas supply. x Emissions have been reduced to below 30 mg / m³ through low-nitrogen technologies, limiting the potential for renewable energy substitution.

[0004] Only by using low-NOx combustion technology to make the emission levels of biomass gas equal to or even lower than those of natural gas can we meet the environmental protection requirements of high-end scenarios such as cities and industries, promote its large-scale application (such as replacing natural gas in industrial boilers and supplementing urban gas pipelines), thereby reducing the consumption of fossil energy and lowering carbon emissions (the carbon emissions of biomass gas throughout its entire life cycle are only 1 / 10 of those of natural gas).

[0005] In the long run, low-NOx combustion is the only way for biomass energy to move from theoretically clean to practically clean. Therefore, the market urgently needs to develop a high-efficiency low-NOx biomass gas burner. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, such as low denitrification efficiency and high cost, the present invention provides a low-NOx burner for biomass gas to solve the technical problems of high NOx emissions, low combustion efficiency and dust pollution caused by biomass gas combustion in the existing technology.

[0007] The technical solution adopted by the present invention to solve its technical problem is as follows: a biomass gas low-NOx burner, comprising a pre-combustion chamber and a fuel delivery pipe, wherein the fuel delivery pipe is connected to the pre-combustion chamber, an outer jacket is installed outside the pre-combustion chamber to form a secondary air passage, and a second cyclone vane is provided at the end of the secondary air passage; an outer jacket is installed on the outer wall of the pre-combustion chamber to form a primary air passage, the primary air passage is connected to the pre-combustion chamber, and a first cyclone vane is provided at the end; a catalytic device is installed inside the fuel injection port of the pre-combustion chamber.

[0008] The catalytic device is a baffle with a honeycomb-shaped permeable area, which is fixed in the pre-combustion chamber; the honeycomb-shaped permeable area has a honeycomb support frame, and a denitrification catalyst is attached to the surface of the honeycomb support frame.

[0009] The denitrification catalyst is one of the following: high-temperature modified V2O5-WO3 / TiO2, high-temperature Cu-CHA molecular sieve, and CeO2-WO3 / TiO2.

[0010] A central air inlet pipe is installed inside the fuel delivery pipe, which is used to inject flue gas drawn from the flue behind the boiler tail dust collector into the end of the fuel delivery pipe and pre-mix it with biomass gas before entering the pre-combustion chamber for combustion.

[0011] The central air inlet pipe has several small holes at its outlet to allow the flue gas to be ejected at high speed.

[0012] The air outlet of the central air inlet pipe is located at the axis of the fuel delivery pipe, and the injection direction is towards the pre-combustion chamber.

[0013] A central tube sleeve is fixedly installed on the fuel delivery pipe. The central air inlet pipe is installed inside the central tube sleeve through a flange. The extended section of the central air inlet pipe passes through the central tube sleeve and extends into the middle of the fuel delivery pipe.

[0014] The primary air duct consists of the outer wall of the fuel delivery pipe and a sleeve installed on the outer wall of the fuel delivery pipe.

[0015] The primary air duct and the secondary air duct are respectively connected to the air inlet pipe.

[0016] The air inlet pipe is installed on the outer wall of the fuel delivery pipe. It is an annular cavity formed by a head plate, an outer ring, refractory concrete, and a cone. The annular cavity is connected to the primary air channel. The annular cavity is connected to the secondary air channel through ventilation holes provided in the cone.

[0017] The inlet of the air inlet pipe is tangentially oriented, and the combustion air enters the air inlet pipe at high speed tangentially from the side.

[0018] The pre-combustion chamber is cylindrical with a length of 2-3d (d is the diameter of the burner body) and an inner diameter of 0.7-0.9d.

[0019] The catalytic device has a honeycomb-shaped permeable area with a pore size of 1-2 mm, and the denitrification catalyst is attached to a thickness of 1-2 mm.

[0020] The diameter of the small hole at the end of the central air inlet pipe is 2-3mm, and the diameter of the central air inlet pipe is 0.2-0.3d.

[0021] Compared with the prior art, the beneficial effects of the present invention are: (1) A honeycomb denitrification catalyst is installed in the pre-combustion chamber to match the high temperature working conditions of the pre-combustion chamber. It has strong thermal stability and is not easy to sinter and deactivate. Nitrogen oxides in biomass gas are degraded under the action of the catalyst, which can effectively reduce the generation of nitrogen oxides.

[0022] (2) The porous structure of the honeycomb catalyst can intercept dust particles in biomass gas, while the high temperature environment causes the intercepted dust particles to burn and decompose, achieving a synergistic effect of catalytic denitrification and dust removal, achieving two goals at once.

[0023] (3) The flue gas is injected into the fuel delivery pipe through the central air intake pipe and pre-mixed with the biomass gas to reduce the oxygen concentration and combustion rate of the mixed gas and further suppress the generation of nitrogen oxides.

[0024] (4) The primary air enters the combustion zone of the pre-combustion chamber in a swirling manner through the first cyclone vane; the secondary air is ejected in a swirling manner through the second cyclone vane to form a secondary combustion zone. The two-stage combustion zones form a stepped combustion, eliminating the high-temperature zone of the flame and further reducing the amount of nitrogen oxides generated.

[0025] (5) The swirl directions of the primary air and the secondary air can be set to be opposite to form a counter-current swirl field in the pre-combustion chamber, which prolongs the residence time of flue gas, enhances the mixing effect of gas and air, and improves combustion efficiency. Attached Figure Description

[0026] Figure 1 This is a three-dimensional structural diagram of a low-NOx biomass combustion burner according to the present invention; Figure 2 This is a rear view structural diagram of a low-NOx biomass combustion gas burner according to the present invention; Figure 3 This is a front view structural diagram of a low-NOx biomass combustion burner according to the present invention; Figure 4 This is a right-side structural view of a low-NOx biomass combustion engine according to the present invention (A is the input direction, B is the output direction). Figure 5 This is a cross-sectional view of the CC section of a low-NOx biomass combustion burner according to the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] A biomass gas low-NOx burner, such as Figure 1-5As shown, it includes a pre-combustion chamber 14 and a fuel delivery pipe 15. The end of the fuel delivery pipe 15 is connected to the pre-combustion chamber 14. A jacket is installed outside the pre-combustion chamber 14 to form a secondary air channel 16. The secondary air channel 16 is provided with a second cyclone vane 12 at its end. The end of the pre-combustion chamber 14 is connected to the furnace to input combustion air into the furnace. A jacket is installed on the outer wall of the pre-combustion chamber 14 to form a primary air channel 17. The primary air channel 17 is connected to the pre-combustion chamber 14 and is provided with a first cyclone vane 1 at its end. A catalytic device 13 is installed inside the fuel injection port of the pre-combustion chamber 14. The catalytic device 13 is a baffle with a honeycomb-shaped permeable area and is fixed inside the pre-combustion chamber 14. The honeycomb-shaped permeable area of ​​the catalytic device 13 has a honeycomb support skeleton, and a denitrification catalyst is attached to the surface of the honeycomb support skeleton. The denitrification catalyst can be a high-temperature modified V2O5-WO3 / TiO2, wherein the V2O5 content is 1.5wt%, the WO3 content is 8wt%, and TiO2 is the carrier.

[0030] A central air inlet pipe 5 is installed inside the fuel delivery pipe 15. This inlet pipe injects flue gas drawn from the flue behind the boiler tail dust collector into the end of the fuel delivery pipe 15, where it is pre-mixed with biomass fuel gas before entering the pre-combustion chamber 14 for combustion. The outlet 18 of the central air inlet pipe 5 has several small holes to allow the flue gas to be ejected at high speed. Preferably, the outlet 18 of the central air inlet pipe 5 is located at the axis of the fuel delivery pipe 15, and the injection direction is towards the pre-combustion chamber 14. The recycled flue gas is injected at high speed through these small holes, pre-mixed with the biomass fuel gas, and first enters the pre-combustion chamber 14 for combustion, creating a high-temperature, low-oxygen combustion environment, which can effectively reduce the generation of nitrogen oxides.

[0031] Preferably, the primary air passage 17 is composed of the outer wall of the fuel delivery pipe 15 and a sleeve 2 disposed on the outer wall of the fuel delivery pipe 15. A central pipe sleeve 3 is fixedly disposed on the fuel delivery pipe 15, and the central air inlet pipe 5 is installed inside the central pipe sleeve 3 through a flange 4. The forward extension of the central air inlet pipe 5 passes through the central pipe sleeve 3 and extends into the middle of the fuel delivery pipe 15.

[0032] The primary air passage 17 and the secondary air passage 16 are respectively connected to the air inlet pipe 10. The air inlet pipe 10 is installed on the outer wall of the fuel delivery pipe 15 and is an annular cavity formed by the end plate 9, the outer ring 8, the refractory concrete 7, and the cone 6. The refractory concrete 7 is coated on the outer wall of the fuel delivery pipe 15 to fix the end plate 9 and the cone 6. The outer ring 8 covers the end plate 9 and the cone 6 to form an annular cavity. The annular cavity is connected to the primary air passage 17. The annular cavity is connected to the secondary air passage 16 through a ventilation hole provided in the cone 6. The inlet of the air inlet pipe 10 is tangentially set. The combustion air enters the air inlet pipe 10 tangentially at high speed from the side and then splits into two paths: one path enters the pre-combustion chamber 14 as primary air through the primary air passage 17 and passes through the first cyclone blade 1 to assist combustion; the other path enters the secondary air passage 16 as secondary air and is sprayed out by the second cyclone blade 12 to further assist in intense combustion. After the biomass gas is ignited and burned in the pre-combustion chamber 14, the temperature rises to 450°C. Under the catalytic action of the honeycomb denitrification catalyst in the catalytic device 13, 80% of the nitrogen oxides (which are generated during biomass gasification) are removed. At the same time as the catalytic device 13 is in contact with the honeycomb skeleton coated with the denitrification catalyst (450°C) for catalysis, the dust in the biomass gas can also be burned off, achieving two goals at once.

[0033] The pre-combustion chamber 14 is cylindrical with a length of 3d and an inner diameter of 0.8d. The catalytic device 13 has a honeycomb-shaped permeable area with a honeycomb pore size of 1mm and a nitrogen removal catalyst thickness of 1mm. The diameter of the small hole at the end of the central air inlet pipe 5 is 3mm, and the diameter of the central air inlet pipe 5 is 0.3d.

[0034] The pre-combustion chamber 14 and fuel delivery pipe 15, among other components, are constructed with a multi-layered annular welded structure. Cyclone vanes are installed at the ends of the primary air channel 17 and secondary air channel 16. When biomass fuel gas mixes with the gas input through the cyclone vanes, they can be fully mixed during rotation. The rotating flame ejected from the burner in the pre-combustion chamber 14 results in good combustion, concentrated flame, high combustion efficiency, and complete combustion. This application employs a two-stage combustion, central air intake structure, complemented by the primary air channel 17, secondary air channel 16, and a honeycomb denitrification catalyst installed within the pre-combustion chamber 14. The primary air channel 17 is connected to the pre-combustion chamber 14 via the first cyclone vane 1; the secondary air channel 16 is connected to the furnace via the second cyclone vane 12. Several small holes are opened on the central air intake pipe 5. Low-temperature flue gas drawn from behind the boiler tail dust collector is injected at high speed through these holes, pre-mixed with the biomass fuel gas, and first combusted in the pre-combustion chamber 14, creating a high-temperature, low-oxygen combustion environment that effectively reduces the generation of nitrogen oxides. Then, most of the nitrogen oxides are removed by a honeycomb-shaped denitrification catalyst before being injected into the furnace and mixed with secondary air for combustion. Combustion air enters the burner at high speed from the side and is then split into two paths. One path, as primary air, enters the pre-combustion chamber 14 through rotating cyclone vanes to aid combustion; the other path, as secondary air, is ejected through rotating cyclone vanes to further strongly assist combustion. After ignition and combustion in the pre-combustion chamber 14, the biomass gas reaches a temperature of 450℃. After passing through the honeycomb-shaped denitrification catalyst, 80% of the nitrogen oxides (generated during biomass gasification) are removed. Simultaneously, the biomass gas passes through the honeycomb-shaped denitrification catalyst at 450℃, which also burns off dust, achieving two benefits at once.

[0035] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the description of the invention shall still fall within the scope of the patent of the present invention.

Claims

1. A low-NOx biomass combustion burner, comprising a pre-combustion chamber and a fuel delivery pipe, characterized in that, The fuel delivery pipe is connected to the pre-combustion chamber. An outer jacket is installed outside the pre-combustion chamber to form a secondary air passage. A second cyclone vane is provided at the end of the secondary air passage. An outer jacket is installed on the outer wall of the pre-combustion chamber to form a primary air passage. The primary air passage is connected to the pre-combustion chamber and a first cyclone vane is provided at the end. A catalytic device is installed inside the fuel injection port of the pre-combustion chamber.

2. The biomass low-NOx burner according to claim 1, characterized in that, The catalytic device is a baffle with a honeycomb-shaped permeable area, which is fixed in the pre-combustion chamber; the honeycomb-shaped permeable area has a honeycomb support frame, and a denitrification catalyst is attached to the surface of the honeycomb support frame.

3. A low-NOx biomass combustion burner according to claim 2, characterized in that, The denitrification catalyst is one of high-temperature modified V2O5-WO3 / TiO2, high-temperature Cu-CHA molecular sieve, and CeO2-WO3 / TiO2. The pore size of the honeycomb permeable region is 1-2 mm, and the thickness of the denitrification catalyst is 1-2 mm.

4. A low-NOx biomass combustion burner according to claim 2, characterized in that, The fuel delivery pipe is equipped with a central air inlet pipe, which is used to inject flue gas drawn from the flue behind the boiler tail dust collector into the end of the fuel delivery pipe and pre-mix it with biomass gas before entering the pre-combustion chamber for combustion.

5. A low-NOx biomass combustion burner according to claim 1, characterized in that, The air outlet of the central air inlet pipe is provided with several small holes, the diameter of which is 2-3mm.

6. A low-NOx biomass combustion burner according to claim 5, characterized in that, The air outlet of the central air inlet pipe is located at the axis of the fuel delivery pipe, and the injection direction is towards the pre-combustion chamber.

7. A low-NOx biomass combustion burner according to claim 6, characterized in that, A central tube sleeve is fixedly installed on the fuel delivery pipe. The central air inlet pipe is installed inside the central tube sleeve through a flange. The extended section of the central air inlet pipe passes through the central tube sleeve and extends into the middle of the fuel delivery pipe.

8. A low-NOx biomass combustion burner according to claim 1, characterized in that, The primary air passage consists of the outer wall of the fuel delivery pipe and a sleeve installed on the outer wall of the fuel delivery pipe; the primary air passage and the secondary air passage are respectively connected to the air inlet pipe.

9. A low-NOx biomass combustion burner according to claim 8, characterized in that, The air inlet pipe is installed on the outer wall of the fuel delivery pipe. It is an annular cavity formed by a head plate, an outer ring, refractory concrete, and a cone. The annular cavity is connected to the primary air channel. The annular cavity is connected to the secondary air channel through ventilation holes provided in the cone.

10. A low-NOx biomass combustion burner according to claim 9, characterized in that, The air inlet of the air inlet is tangentially oriented, allowing combustion air to enter at high speed tangentially from the side.

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