A kiln gas-solid combustor based on semi-gasification reaction

Abstract

The present application belongs to the field of energy saving and environmental protection technology, and discloses a kiln gas-solid combustor based on semi-gasification reaction, which comprises a fuel supply structure and a semi-gasification structure. One end of the semi-gasification structure is an outer end part located outside the furnace wall, and the other end is an inner end part extending into the furnace wall. One end of the fuel supply structure is an input end for inputting solid fuel, and the other end is an output end for outputting fuel connected with the outer end part. The fuel premixing structure is used for supplying fuel. The outer end part is used for inputting combustion-supporting gas and fuel. The semi-gasification structure comprises a gas-solid semi-pyrolysis channel. The gas-solid semi-pyrolysis channel is located in the furnace wall and is used for semi-gasification reaction of the fuel passing through. The gas-solid semi-pyrolysis channel is communicated with the semi-gasification gas nozzle of the inner end part. The present application reduces the ignition point at the semi-gasification gas outlet, so that the semi-gasification gas sprayed by the combustor can be burned more effectively, the combustion efficiency is improved, and the energy saving and environmental protection effect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving and environmental protection technology, and specifically relates to a kiln gas-solid burner based on a semi-gasification reaction. Background Technology

[0002] Kiln burners can use gaseous or solid fuels such as natural gas and pulverized coal for combustion. In existing technologies, burners using gaseous fuels, such as natural gas and hydrogen, are in a gaseous state under standard conditions. The advantage of these fuels is that they generally have a low ignition point and are easy to ignite. However, they suffer from low flame emissivity and low radiative heat transfer flux, leading to low energy utilization. In contrast, solid fuel combustion produces more high-temperature particulate matter, such as high-temperature soot particles and semi-coke particles, resulting in higher flame emissivity and radiative heat transfer flux. However, even finely ground pulverized coal has a lower ignition point and lower flammability than gaseous fuels. Simply mixing gaseous and solid fuels and igniting them can utilize the flammability of gaseous fuels to some extent, making the burner easier to ignite. However, due to the lower heat transfer efficiency of gaseous fuels and the higher ignition point of solid fuels, simply mixing the two states of fuel in a rapidly flowing environment cannot guarantee complete ignition of the mixed solid fuel, resulting in insufficient combustion effect and reliability. Summary of the Invention

[0003] The purpose of this invention is to provide a kiln gas-solid burner based on semi-gasification reaction, which solves the technical problems of low flame emissivity and radiative heat transfer flux of gas fuel combustion flue gas in the prior art, and insufficient actual combustion effect and reliability of the burner.

[0004] A kiln gas-solid burner based on a semi-gasification reaction includes a fuel supply structure and a semi-gasification structure. One end of the semi-gasification structure is an outer end located outside the furnace wall, and the other end is an inner end extending into the furnace wall. One end of the fuel supply structure is an input end for inputting solid fuel, and the other end is an output end connected to the outer end for outputting fuel. A fuel premixing structure is used to supply fuel, and the outer end is used to input combustion-supporting gas and fuel. The semi-gasification structure includes a gas-solid semi-pyrolysis channel located inside the furnace wall and used to allow the passing fuel to undergo a semi-gasification reaction. The gas-solid semi-pyrolysis channel is connected to the semi-gasification gas nozzle at the inner end. The semi-gasification reaction includes cases where only part of the fuel undergoes gasification, and also cases where the gasification reaction only involves the removal of volatiles and incomplete gasification.

[0005] Preferably, the semi-gasification structure further includes a gas-solid semi-pyrolysis cylinder, semi-pyrolysis channel swirl blades, and a high-temperature air channel. The gas-solid semi-pyrolysis channel is disposed inside the gas-solid semi-pyrolysis cylinder. The high-temperature air channel is connected to the gas-solid semi-pyrolysis channel via the outer end. The output end of the fuel supply structure is connected to the gas-solid semi-pyrolysis channel via the outer end. The semi-pyrolysis channel swirl blades are arranged on the inner circumferential surface of the gas-solid semi-pyrolysis channel. A set of semi-pyrolysis channel swirl blades are arranged in a circular array with the central axis of the gas-solid semi-pyrolysis channel as the center. The center of the array structure formed by the circular array is a hollow channel.

[0006] Preferably, the swirl angle of the semi-pyrolysis channel swirl blades ranges from 45° to 60°, the width of the semi-pyrolysis channel swirl blades ranges from 1 / 6D2 to 1 / 4D2, and the length of the gas-solid semi-pyrolysis channel ranges from 5D2 to 10D2, where D2 refers to the inner diameter of the gas-solid semi-pyrolysis channel.

[0007] Preferably, the fuel supply structure is a fuel premixing structure, the axis of the fuel premixing structure coincides with the axis of the semi-gasification structure, the input end is also used to input gaseous fuel, and the fuel premixing structure is used to mix gaseous fuel and solid fuel to form a gas-solid mixed fuel before outputting it.

[0008] Preferably, the fuel premixing structure includes a gas-solid mixing channel, a gaseous fuel inlet channel, and a solid fuel air supply duct. The gas-solid mixing channel is located between the input end and the output end, and outside the semi-gasification structure. Both the gaseous fuel inlet channel and the solid fuel air supply duct are connected to the gas-solid mixing channel via the input. The gas-solid mixing channel is provided with solid fuel air supply swirl blades, and the output end is provided with a gas-solid mixing nozzle that extends into the semi-gasification structure.

[0009] Preferably, the solid fuel air supply swirl blades are arranged on the inner circumferential surface of the gas-solid mixing channel, and a group of solid fuel air supply swirl blades are arranged in a circular array with the central axis of the gas-solid mixing channel as the center. The center of the array structure formed by the circular array is a hollow channel. The swirl angle of the solid fuel air supply swirl blades is in the range of 45° to 60°, the width of the solid fuel air supply swirl blades is in the range of 1 / 6D1 to 1 / 4D1, and the length of the gas-solid mixing channel is in the range of 5D1 to 10D1, where D1 refers to the inner diameter of the gas-solid mixing channel.

[0010] Preferably, the gas-solid mixing nozzle is concentric with the gas-solid semi-pyrolysis channel. The gas-solid mixing nozzle has a constriction-expansion structure, which first narrows and then expands from the starting end face connected to the output end. The constriction-expansion structure has a throat portion with a diameter smaller than the diameter of the starting end and an outlet with a diameter larger than the diameter of the throat portion. The outlet is located at the opening of the high-temperature air channel.

[0011] Preferably, a plurality of gaseous fuel inlet channels are arranged circumferentially at the end face of the input end. The gaseous fuel inlets are arranged symmetrically about the axis of the gas-solid mixing channel. The number of gaseous fuel inlet channels is even. The nozzles of the gaseous fuel inlet channels are arranged at an incident angle of less than 90° with the end face of the input end. At the same time, the axis of the nozzles does not intersect with the axis of the gas-solid mixing channel. The swirling direction of the gaseous fuel output from the gaseous fuel inlet channels is consistent with the flow direction generated by the solid fuel air swirl blades.

[0012] Preferably, the incident angle of the gas fuel inlet channel is in the range of 5° to 30°, and a regulating valve is provided on the gas fuel inlet channel to regulate the injection speed and flow rate of the gas fuel.

[0013] This invention has the following advantages: It achieves a semi-gasification reaction of solid fuel within the burner through a semi-gasification structure, producing a large amount of soot and semi-coke. The amount of soot and semi-coke particles carried in the flame is crucial for improving the flame's radiative heat transfer capacity. Therefore, this solution can effectively improve flame emissivity and radiative heat transfer flux, enhancing the intensity of the combustion flame. Simultaneously, since the semi-gasification reaction produces combustible gas, which is more easily ignited and burned, the ignition point at the semi-gasification gas nozzle is lowered, allowing the semi-gasified gas ejected from the burner to burn more effectively, improving combustion efficiency and achieving energy-saving and environmentally friendly effects.

[0014] Since the semi-gasification reaction requires endothermic reaction and the solid fuel itself has a high ignition point, this invention also uses a fuel premixing structure as the fuel supply structure. The gaseous fuel and solid fuel are premixed and injected into the gas-solid semi-pyrolysis channel. The low-ignition-point gaseous fuel is mixed with the solid fuel and then fed into the gas-solid semi-pyrolysis cylinder. The large amount of heat generated during the combustion of the flammable gaseous fuel heats the solid fuel, promoting a stronger semi-gasification reaction. This also allows the semi-gasified gas to form a glowing flame combustion effect.

[0015] In this scheme, the fuel premixing structure utilizes the structure of the gas-solid mixing nozzle to increase the axial velocity of the gas-solid mixed fuel, allowing it to be ejected from the nozzle at a high flow rate into the gas-solid semi-pyrolysis channel while simultaneously ensuring thorough mixing of the two fuels. The high-temperature air is accelerated by the high-speed injection of the gas-solid mixed fuel, and the swirling blades further promote a swirling effect, entraining the gas-solid mixed fuel in the central jet state. This ensures that the peripheral gas-solid mixed fuel is in an oxygen-rich atmosphere, allowing for complete combustion with the lowered ignition point of the mixed gaseous fuel. Simultaneously, the gas-solid mixed fuel has a high axial velocity, preventing the swirling high-temperature air from entering the axially injected fluid interior of the gas-solid mixed fuel in the front section of the gas-solid semi-pyrolysis channel. Ignition and combustion at the boundary between the gas-solid mixed fuel and the high-temperature air leads to a decrease in the oxygen concentration of the air (introduced pneumatically) within the gas-solid mixed fuel. Therefore, the interior of the gas-solid mixed fuel experiences an oxygen-deficient atmosphere due to insufficient oxygen supply during its flow. Thus, by combining the semi-gasification structure of the burner with the structure of the gas-solid mixing nozzle, this invention achieves the following: while transporting mixed fuel and high-temperature air for combustion within the burner, the heat released by the combustion of the gaseous fuel allows the solid fuel in the gas-solid mixture to undergo a certain degree of semi-gasification reaction, and then the resulting semi-gasified gas is ejected and ignited. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a kiln gas-solid burner based on a semi-gasification reaction according to the present invention.

[0017] Figure 2 for Figure 1 The diagram shows a schematic of the nozzle arrangement structure of the gas fuel inlet channel.

[0018] Figure 3 for Figure 1 A schematic diagram of the semi-gasification reaction and combustion process of the gas-solid mixed fuel in the structure shown.

[0019] The reference numerals in the attached figures include: 1. Gaseous fuel inlet channel; 2. Solid fuel air swirl vane; 3. Gas-solid mixing channel; 4. Gas-solid semi-pyrolysis cylinder; 5. Semi-pyrolysis channel swirl vane; 6. Gas-solid mixing nozzle; 7. Furnace wall; 8. Gas-solid semi-pyrolysis channel; 9. Semi-gasified gas nozzle; 10. Nozzle; 11. Solid fuel air duct; 12. High-temperature air channel; 13. Flame stabilizer; 801. Combustion flame in the channel; 802. Unburned gas-solid mixed fuel; 803. Semi-gasified gas area; 804. Boundary between the combustion flame and unburned gas-solid mixed fuel in the channel; 805. Semi-gasified gas boundary; 806. Flame at the nozzle; 807. Mixing zone. Detailed Implementation

[0020] The following detailed description of the embodiments, with reference to the accompanying drawings, will further illustrate the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate, and thorough understanding of the inventive concept and technical solutions of the present invention.

[0021] like Figures 1-3 As shown, this invention provides a kiln gas-solid burner based on a semi-gasification reaction, where "gas-solid" refers to both gaseous and solid fuels. The kiln gas-solid burner includes a fuel supply structure and a semi-gasification structure with their axes coincident. One end of the semi-gasification structure is an outer end located outside the furnace wall 7, and the other end is an inner end extending into the furnace wall 7. One end of the fuel supply structure is an input end for solid fuel, and the other end is an output end connected to the outer end for fuel output. A fuel premixing structure is used to supply fuel, and the outer end is used to input combustion-supporting gas and fuel. The semi-gasification structure includes a gas-solid semi-pyrolysis channel 8, located within the furnace wall 7, which allows the passing fuel to undergo a semi-gasification reaction. The gas-solid semi-pyrolysis channel 8 is connected to a semi-gasification gas nozzle 9 at the inner end.

[0022] The semi-gasification structure also includes a gas-solid semi-pyrolysis cylinder 4, semi-pyrolysis channel swirl blades 5, and a high-temperature air channel 12. The gas-solid semi-pyrolysis channel 8 is located inside the gas-solid semi-pyrolysis cylinder 4. The high-temperature air channel 12 is connected to the gas-solid semi-pyrolysis channel 8 through its outer end. The output end of the fuel supply structure is connected to the gas-solid semi-pyrolysis channel 8 through its outer end. The semi-pyrolysis channel swirl blades 5 are arranged on the inner circumferential surface of the gas-solid semi-pyrolysis channel 8. A group of semi-pyrolysis channel swirl blades 5 are arranged in a circular array with the central axis of the gas-solid semi-pyrolysis channel 8 as the center. The center of the array structure formed by the circular array is a hollow channel.

[0023] The swirl angle of the semi-pyrolysis channel swirl blades 5 ranges from 45° to 60°, the width of the semi-pyrolysis channel swirl blades 5 ranges from 1 / 6D2 to 1 / 4D2 (i.e., 1 / 6 to 1 / 4 of the inner diameter of the gas-solid semi-pyrolysis channel 8), and the length of the gas-solid semi-pyrolysis channel 8 ranges from 5D2 to 10D2 (i.e., 5 to 10 times the inner diameter of the gas-solid semi-pyrolysis channel 8), where D2 refers to the inner diameter of the gas-solid semi-pyrolysis channel 8. Both the gas-solid semi-pyrolysis cylinder 4 and the semi-pyrolysis channel swirl blades 5 are made of high-temperature resistant thermally conductive materials, thereby utilizing the high temperature inside the kiln to heat the internal fuel, which is beneficial for its temperature rise and pyrolysis and gasification under oxygen-deficient conditions.

[0024] The relatively long gas-solid semi-pyrolysis channel 8 allows the solid fuel to be fully heated within the channel, resulting in a certain degree of gasification. This semi-gasification effect is achieved due to incomplete gasification. Semi-gasification refers to the partial or incomplete gasification of solid fuel within the region. This includes situations where not all fuel is gasified, but only a portion is, and situations where only the portion undergoing gasification undergoes partial removal of volatiles. Taking pulverized coal as an example, during the brief passage through the initial section of the gas-solid semi-pyrolysis channel 8, not all pulverized coal is gasified; only a portion undergoes the gasification reaction. Furthermore, most pulverized coal does not undergo sufficient gasification and instead undergoes a partial gasification reaction involving the removal of volatiles. This results in the formation of finer-particle-size soot and semi-coke with a more porous structure. The surface area of ​​this semi-coke is much larger than that of the pulverized coal, significantly increasing its reactivity. The substances produced by the semi-gasification reaction mix with the surrounding substances to form semi-gasified gas.

[0025] The fuel supply structure is a fuel premixing structure, with its axis coinciding with the axis of the semi-gasification structure. The input end is also used to input gaseous fuel, and the fuel premixing structure is used to mix the gaseous fuel and solid fuel to form a gas-solid mixture before outputting it. Although the semi-gasification structure in this invention can cause powdered solid fuel to undergo a semi-gasification reaction, thereby producing a certain amount of combustible gas, the solid fuel is not easily ignited, and the heat generated by combustion in the burner is limited. Furthermore, the semi-gasification reaction is endothermic, so achieving the semi-gasification reaction solely through solid fuel has limited effectiveness. Therefore, this invention employs a fuel premixing structure, mixing the low-ignition-point gaseous fuel with the solid fuel and then feeding it into the gas-solid semi-pyrolysis cylinder 4. The large amount of heat generated during the combustion of the flammable gaseous fuel heats the solid fuel, promoting a stronger semi-gasification reaction. In this process, the heat provided by the combustion of the gaseous fuel accounts for the majority of the heat required for the semi-gasification reaction.

[0026] The fuel premixing structure includes a gas-solid mixing channel 3, a gaseous fuel inlet channel 1, and a solid fuel air supply duct 11. The gas-solid mixing channel 3 is located between the input end and the output end, and outside the semi-gasification structure. The gaseous fuel inlet channel 1 and the solid fuel air supply duct 11 are both connected to the gas-solid mixing channel 3 via the input. The gas-solid mixing channel 3 is provided with solid fuel air supply swirl blades 2. The output end is provided with a gas-solid mixing nozzle 6 that extends into the semi-gasification structure.

[0027] The solid fuel air-supplying swirl blades 2 are arranged on the inner circumferential surface of the gas-solid mixing channel 3. A group of solid fuel air-supplying swirl blades 2 are arranged in a circular array with the central axis of the gas-solid mixing channel 3 as the center. The center of the array structure formed by the circular array is a hollow channel. The swirl direction of the semi-pyrolysis channel swirl blades 5 is opposite to that of the solid fuel air-supplying swirl blades 2. The opposite swirl direction can reduce the mixing speed of the gas-solid mixed fuel with the high-temperature air after it is ejected, making it less likely for the gas-solid mixed fuel inside to come into contact with the high-temperature air that supports combustion, thus keeping it in the oxygen-deficient state required for pyrolysis and gasification.

[0028] The solid fuel air-blowing swirl blade 2 has a swirl angle ranging from 45° to 60°, a width ranging from 1 / 6D1 to 1 / 4D1 (i.e., 1 / 6 to 1 / 4 of the inner diameter of the gas-solid mixing channel 3), and a length ranging from 5D1 to 10D1 (i.e., 5 to 10 times the inner diameter of the gas-solid mixing channel 3), where D1 refers to the inner diameter of the gas-solid mixing channel 3. Because the solid fuel air-blowing swirl blade 2 has a large swirl angle and blade width, and because the gas-solid mixing channel 3 is relatively long, the fuel premixing structure enhances the swirl effect of the gas-solid mixed fuel on the one hand, and significantly reduces the axial velocity of the gas-solid mixed fuel through the longer channel structure, thereby ensuring thorough mixing of the two fuels within the gas-solid mixing channel 3.

[0029] The gas-solid mixing nozzle 6 is concentric with the gas-solid semi-pyrolysis channel 8. The gas-solid mixing nozzle 6 first narrows and then widens from the starting end face connected to the output end; that is, the gas-solid mixing nozzle 6 has a narrowing-and-widening structure. This structure has a throat portion with a diameter smaller than the diameter of the starting end and an outlet with a diameter larger than the diameter of the throat portion. The outlet is located at the opening of the high-temperature air channel 12. This structure allows the gas-solid fuel flow velocity to increase rapidly at the throat portion, thereby reducing the flame propagation speed during combustion to be lower than the fuel flow velocity at the outlet of the gas-solid mixing nozzle 6, which can, to some extent, prevent the possibility of backfire explosion.

[0030] The end face of the gas-solid mixing channel 3 (i.e., the starting face of the output end) is provided with a grid-structured flame stabilizer 13, which is made of wear-resistant materials such as silicon carbide. Since the gas-solid mixed fuel passing through the flame stabilizer 13 contains solid fuels such as pulverized coal, it causes significant wear on the flame stabilizer 13. Therefore, wear-resistant materials are required to prevent wear from the flame stabilizer 13 during long-term operation. The flame stabilizer 13 prevents backfire because during transportation, solid and gaseous fuels mix in an atmosphere containing air, similar to the premixing of fuel and oxidizer, which carries the risk of backfire and explosion. With the flame stabilizer 13 installed, when the gas-solid mixed fuel passes through it, a gas recirculation zone is created around the flame stabilizer 13, resulting in strong turbulence. Therefore, the gas-solid mixed fuel flow velocity distribution range in the recirculation zone is wide, and a certain gas-solid mixed fuel flow velocity will match the flame propagation velocity during combustion. When the flame propagation velocity is the same as the gas-solid mixed fuel flow velocity, backfire can be prevented.

[0031] A plurality of gaseous fuel inlet channels 1 are arranged circumferentially at the end face of the input end. The gaseous fuel inlets are centrally symmetrically arranged around the axis of the gas-solid mixing channel 3, and the number of gaseous fuel inlet channels 1 is even. The nozzle 10 of the gaseous fuel inlet channel 1 is positioned at an incident angle of less than 90° with the end face of the input end, and the axis of the nozzle 10 does not intersect with the axis of the gas-solid mixing channel 3. The swirling direction of the gaseous fuel output from the gaseous fuel inlet channel 1 is consistent with the flow direction generated by the solid fuel airflow swirl blades 2. This not only improves the swirling degree of the solid fuel airflow in the gas-solid mixing channel 3, but also ensures thorough mixing of the gaseous fuel and solid fuel.

[0032] The incident angle of the gaseous fuel inlet channel 1 ranges from 5° to 30°. A regulating valve is installed on the gaseous fuel inlet channel 1, and the opening degree of multiple gaseous fuel inlet channels 1 can be adjusted simultaneously through a control system, thereby regulating the injection speed and flow rate of the gaseous fuel. The regulating valve can also be located at the gaseous fuel supply port and is similarly symmetrically distributed.

[0033] The method of using the kiln gas-solid burner includes: gaseous fuel is injected into the gas-solid mixing channel 3 from the gaseous fuel inlet channel 1, while solid fuel is simultaneously supplied from the solid fuel air supply duct 11. The gaseous fuel includes natural gas, hydrogen, liquefied petroleum gas, solid waste gasification gas, biomass gasification gas, coal chemical synthesis gas, etc., which are in a gaseous state under standard conditions and have a certain calorific value. The solid fuel refers to combustible powder that has been ground to a certain fineness and can be pneumatically transported, including coal powder, biomass powder, solid waste powder, etc. The flow direction of the gaseous fuel is at a certain angle to the axis of the gas-solid mixing channel 3, and the swirling direction of the gaseous fuel after entering is consistent with the swirling direction generated by the solid fuel air supply swirl blades 2.

[0034] Solid fuels are transported pneumatically, with an air velocity of approximately 30-50 m / s. The solid-to-gas mass ratio in pneumatic transport needs to be adjusted based on the density and fineness of the solid fuel. Furthermore, to maintain pneumatic transport of solid fuels, it must be ultimately determined based on the fuel equivalence ratio (φ needs to be maintained above 50) (the solid-to-gas mass ratio is generally in the range of 4-6). Adjusting the solid-to-gas mass ratio is primarily due to the varying elemental compositions of different solid fuels, and is also limited by their oxygen content. Since a high-oxygen-content air atmosphere cannot be provided for pneumatic transport, it is necessary to reduce the risk of direct ignition between gaseous and solid fuels within the gas-solid mixing channel 3.

[0035] The total heat supplied by gaseous fuel accounts for 0-30% of the total heat supplied by the gas-solid mixture (if the proportion is 0, i.e., only solid fuel is supplied without adding gaseous fuel). The control system precisely matches the following three key parameters: ① the opening of the regulating valve controlling the gaseous fuel supply, thereby determining the flow rate and velocity of the injected gaseous fuel; ② the pneumatic conveying velocity; ③ the supply amount of solid fuel. These key parameters ensure that: ① the total heat supplied by gaseous fuel accounts for 0-30% of the total heat supplied by the gas-solid mixture; ② solid fuel is pneumatically conveyed; ③ the burner power meets the kiln combustion requirements, and the total heat load supplied by both gaseous and solid fuels is the burner power.

[0036] After the gaseous fuel and solid fuel are thoroughly mixed, a gas-solid mixed fuel is ejected from the gas-solid mixing nozzle 6 and enters the gas-solid semi-pyrolysis cylinder 4. Finally, the fuel premixing structure utilizes the structure of the gas-solid mixing nozzle 6 to increase the axial velocity of the gas-solid mixed fuel, causing it to be ejected from the gas-solid mixing nozzle 6 at a higher flow rate into the gas-solid semi-pyrolysis channel 8. The gas-solid mixed fuel ejected from the gas-solid mixing nozzle 6 with its constricted and expanded structure has a relatively high flow rate, which can entrain the high-temperature air entering from the high-temperature air channel 12, increasing the airflow velocity of the gas-solid mixed fuel and the high-temperature air in the gas-solid semi-pyrolysis channel 8. The temperature of the high-temperature air is not lower than 600°C; in this embodiment, high-temperature air at approximately 800°C is sent into the gas-solid semi-pyrolysis channel 8 from the high-temperature air channel 12. The supply of high-temperature air is controlled by a control system based on the combustion equivalence ratio of the gas-solid mixed fuel, which ranges from 9 to 12.

[0037] After high-temperature air is introduced into the gas-solid semi-pyrolysis channel 8 from the high-temperature air channel 12, its flow velocity is increased by the ejection effect of the high-speed input gas-solid mixed fuel. At the same time, the swirl blades 5 of the semi-pyrolysis channel increase the swirling effect of the high-temperature air. Since the solid semi-pyrolysis channel structure extends into the furnace wall 7, the furnace combustion conditions transfer heat to the gas-solid semi-pyrolysis channel 8, thus further increasing the temperature inside the gas-solid semi-pyrolysis channel 8.

[0038] In detail, the swirling effect of the high-temperature air entrains the gas-solid mixture in the central jet, while the peripheral gas-solid mixture is entrained by the high-temperature air and placed in an oxygen-rich environment. Because the ignition point of the gaseous fuel in the gas-solid mixture is relatively low, and the temperature of the high-temperature air exceeds the ignition point of the gaseous fuel, the gas-solid mixture ignites after mixing with the high-temperature air, forming a combustion flame 801 within the channel. Therefore, near the gas-solid mixing nozzle 6, a relatively clear boundary appears between the combustion flame 801 and the unburned gas-solid mixture 802 within the channel. This boundary also serves as the boundary between the unburned gas-solid mixture 802 and the high-temperature air.

[0039] Ignition and combustion at the boundary between the gas-solid fuel and the high-temperature air leads to a decrease in the oxygen concentration of the air (which is mixed in by pneumatic conveying) in the gas-solid fuel mixture. Simultaneously, because the swirl blades 5 of the semi-pyrolysis channel enhance the swirling effect of the high-temperature air, and the gas-solid fuel injected by the gas-solid mixing nozzle 6 has a high axial velocity, the high-temperature air in the swirling state cannot enter the fluid interior of the axially injected gas-solid fuel mixture in the front section of the gas-solid semi-pyrolysis channel 8. Therefore, the gas-solid fuel mixture is in an oxygen-deficient atmosphere due to insufficient oxygen supply, and no obvious flame will appear. At the same time, this unburned gas-solid fuel mixture 802 is heated by three factors: ① the mixing of high-temperature air inside the gas-solid semi-pyrolysis channel 8; ② the high-temperature baking of the external kiln; ③ the radiative heat transfer from the combustion flame 801 within the gas-solid semi-pyrolysis channel 8. Due to the effects of the above three factors, the gas-solid fuel mixture is in a high-temperature and oxygen-deficient atmosphere, which causes a pyrolysis reaction, that is, the unburned gas-solid fuel mixture 802 undergoes a semi-gasification reaction in an oxygen-deficient atmosphere.

[0040] The amount of soot and semi-coke particles carried in a flame is crucial for enhancing its radiative heat transfer capacity. Therefore, the radiative heat transfer coefficient of solid particles in a solid fuel flame is significantly higher than that of gaseous fuel combustion alone. It's important to note that, at the microscopic scale of the flame, the radiative heat transfer intensity of gaseous fuel combustion alone is also provided by the high-temperature soot particles generated during the incomplete combustion process. This is because the emissivity of high-temperature soot particles is far greater than that of gaseous fuels such as methane, carbon monoxide, and hydrogen. The number and density of soot particles generated by the combustion of gaseous fuels alone are much smaller than those of solid fuels, which is the main reason why the radiative intensity of gaseous fuel combustion flames is lower than that of solid fuel combustion flames.

[0041] Soot and semi-coke gradually begin to form along the fuel's extension direction, first forming a mixing zone 807 as it flows towards the semi-gasification gas nozzle 9. Along the axial direction of the gas-solid semi-pyrolysis channel 8 (which is also the fuel's extension direction), the accumulation of high-temperature air entrainment of the gas-solid mixture along the extension direction leads to continuously enhanced combustion and increased heat release. The combustion flame 801 near the gas-solid semi-pyrolysis channel 8 also gradually expands, causing the unburned gas-solid mixture 802 to receive radiative heat transfer, and the semi-gasification reaction in the semi-gasification gas region 803 also continuously intensifies. Therefore, the boundary 804 between the combustion flame and the unburned gas-solid mixture within the channel gradually blurs and cannot form a clear boundary. The combustion flame 801 and the unburned gas-solid mixture 802 within the channel also gradually mix to form a mixing zone 807, in which it is impossible to distinguish between the combustion flame 801 and the gas-solid mixture. Starting from mixing zone 807, the combustion of gaseous fuel and the pyrolysis and gasification of solid fuel become increasingly intense, but the mixing zone 807 is still in an oxygen-deficient state overall. Solid fuel undergoes a semi-gasification reaction, and the combustion of gaseous fuel also provides more sufficient reaction conditions for the pyrolysis and gasification reaction of solid fuel.

[0042] Upon reaching the latter part of the gas-solid semi-pyrolysis channel 8 (near the semi-gasified gas nozzle 9), a semi-gasified gas region 803 is formed. A semi-gasified gas boundary 805 is formed between the semi-gasified gas region 803, the mixing zone 807, and the combustion flame 801 within the channel. In the semi-gasified gas region 803, the swirling flow formed by the gas-solid mixed fuel and high-temperature air carries soot particles and semi-coke particles, resulting in a more vigorous semi-gasification reaction. This further increases the amount of high-temperature particulate matter carried in this region, such as soot particles and semi-coke particles, thereby correspondingly increasing the amount of high-temperature particulate matter carried in the flame at the burner outlet (also soot particles and semi-coke particles). The semi-gasified gas includes gasification products and ungasified substances. The gasification products include soot particles, semi-coke particles, solid fuel volatiles, and a variety of complex free radicals. The ungasified substances include solid fuel and gaseous fuel. Carbon soot particles, semi-coke particles, solid fuel volatiles, and some free radicals originate from the semi-gasification reaction of solid fuels, while other free radicals originate from the conversion of gaseous fuels during the semi-gasification reaction.

[0043] High-temperature semi-gasified gas is generated in large quantities within the semi-gasified gas region 803, and then passes through the semi-gasified gas nozzle 9 at the inner end. The nozzle 9 has a constricted structure and can increase the flow velocity of the semi-gasified gas. The high-temperature semi-gasified gas is injected into the kiln. Due to the high-temperature environment and sufficient oxygen content inside the kiln, the high-temperature semi-gasified gas ignites and burns on a large scale once it is ejected, forming a bright nozzle flame 806 at the nozzle 9. The nozzle flame 806 is actually formed by the combustion of semi-gasified gas. Unlike the flames formed by the combustion of solid fuels or gaseous fuels alone, semi-gasified gas is actually a new fuel mixture formed by the partial pyrolysis of gas-solid mixed fuels. Because it contains a large number of carbon soot particles and semi-coke particles, it has high activity and reactivity. Compared to the activation energy required for the combustion of single solid fuels and gaseous fuels, the activation energy required for the ignition and combustion of semi-gasified gas is lower, meaning the ignition threshold for semi-gasified gas is relatively low. Therefore, after the semi-gasified gas generated by this invention is ejected, it will rapidly ignite and burn during the diffusion process, both at the boundary and inside of the semi-gasified gas flow field, thus forming a glowing flame. In contrast, the fuel flow field ejected by traditional burners is characterized by high oxygen concentration and high temperature in its boundary region, resulting in relatively complete ignition. However, the oxygen concentration and temperature inside the flow field are low, making ignition difficult. Therefore, traditional burners exhibit a state where there is a flame on the outside of the outlet but no flame inside. At the same time, the semi-gasified gas generated by this invention carries a large number of carbon soot particles, semi-coke particles, solid fuel volatiles, and a variety of complex free radicals, resulting in a flame with high emissivity and strong radiative heat transfer performance.

[0044] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A kiln gas-solid burner based on a semi-gasification reaction, characterized in that: The structure includes a fuel supply structure and a semi-gasification structure. The fuel supply structure is a fuel premixing structure. One end of the semi-gasification structure is an outer end located outside the furnace wall (7), and the other end is an inner end extending into the furnace wall (7). One end of the fuel supply structure is an input end for inputting solid fuel, and the other end is an output end connected to the outer end for outputting fuel. The fuel premixing structure is used to supply fuel, and the outer end is used to input combustion-supporting gas and fuel. The semi-gasification structure includes a gas-solid semi-pyrolysis channel (8), which is located inside the furnace wall (7) and is used to allow the fuel passing through to undergo a semi-gasification reaction. The gas-solid semi-pyrolysis channel (8) is connected to the semi-gasification gas nozzle (9) at the inner end. The semi-gasification reaction includes a situation where only part of the fuel is gasified, and also a situation where the part that undergoes the gasification reaction only undergoes incomplete gasification to remove volatiles. The fuel premixing structure includes a gas-solid mixing channel (3), a gas fuel inlet channel (1), and a solid fuel air supply channel (11). The gas-solid mixing channel (3) is located between the input end and the output end, and outside the semi-gasification structure. The gas fuel inlet channel (1) and the solid fuel air supply channel (11) are both connected to the gas-solid mixing channel (3) via the input. The gas-solid mixing channel (3) is provided with solid fuel air supply swirl vanes (2). The output end is provided with a gas-solid mixing nozzle (6) that extends into the semi-gasification structure. A plurality of gas fuel inlet channels (1) are arranged circumferentially at the end face of the input end. The gas fuel inlets are arranged symmetrically around the axis of the gas-solid mixing channel (3). The number of gas fuel inlet channels (1) is even. The nozzle (10) of the gas fuel inlet channel (1) is arranged in a direction that forms an incident angle of less than 90° with the end face of the input end. At the same time, the axis of the nozzle (10) does not intersect with the axis of the gas-solid mixing channel (3). The swirling direction of the gas fuel output by the gas fuel inlet channel (1) is consistent with the flow direction generated by the solid fuel air swirl blade (2).

2. A kiln gas-solid burner based on a semi-gasification reaction according to claim 1, characterized in that: The semi-gasification structure also includes a gas-solid semi-pyrolysis cylinder (4), semi-pyrolysis channel swirl blades (5), and a high-temperature air channel (12). The gas-solid semi-pyrolysis channel (8) is located inside the gas-solid semi-pyrolysis cylinder (4). The high-temperature air channel (12) is connected to the gas-solid semi-pyrolysis channel (8) through its outer end. The output end of the fuel supply structure is connected to the gas-solid semi-pyrolysis channel (8) through its outer end. The semi-pyrolysis channel swirl blades (5) are arranged on the inner circumferential surface of the gas-solid semi-pyrolysis channel (8). A set of semi-pyrolysis channel swirl blades (5) are arranged in a circular array with the central axis of the gas-solid semi-pyrolysis channel (8) as the center. The center of the array structure formed by the circular array is a hollow channel.

3. A kiln gas-solid burner based on a semi-gasification reaction according to claim 2, characterized in that: The swirl angle of the semi-pyrolysis channel swirl blade (5) ranges from 45° to 60°, the width of the semi-pyrolysis channel swirl blade (5) ranges from 1 / 6D2 to 1 / 4D2, and the length of the gas-solid semi-pyrolysis channel (8) ranges from 5D2 to 10D2, where D2 refers to the inner diameter of the gas-solid semi-pyrolysis channel (8).

4. A kiln gas-solid burner based on a semi-gasification reaction according to any one of claims 2-3, characterized in that: The axis of the fuel premixing structure coincides with the axis of the semi-gasification structure. The input end is also used to input gaseous fuel. The fuel premixing structure is used to mix gaseous fuel and solid fuel to form a gas-solid mixed fuel before outputting it.

5. A kiln gas-solid burner based on a semi-gasification reaction according to claim 4, characterized in that: The solid fuel air supply swirl blades (2) are arranged on the inner circumferential surface of the gas-solid mixing channel (3). A set of solid fuel air supply swirl blades (2) are arranged in a circular array with the central axis of the gas-solid mixing channel (3) as the center. The center of the array structure formed by the circular array is a hollow channel. The swirl angle of the solid fuel air supply swirl blades (2) is 45°~60°. The width of the solid fuel air supply swirl blades (2) is 1 / 6D1-1 / 4D1. The length of the gas-solid mixing channel (3) is 5D1-10D1. D1 refers to the inner diameter of the gas-solid mixing channel (3).

6. A kiln gas-solid burner based on a semi-gasification reaction according to claim 5, characterized in that: The gas-solid mixing nozzle (6) is concentric with the gas-solid semi-pyrolysis channel (8). The gas-solid mixing nozzle (6) is a constriction-expansion structure, which first narrows and then expands from the starting end face connected to the output end. The constriction-expansion structure has a throat portion with a diameter smaller than the diameter of the starting end and an outlet with a diameter larger than the diameter of the throat portion. The outlet is located at the opening of the high-temperature air channel (12).

7. A kiln gas-solid burner based on a semi-gasification reaction according to claim 6, characterized in that: The incident angle of the gas fuel inlet channel (1) is in the range of 5°~30°. A regulating valve is provided on the gas fuel inlet channel (1) to regulate the ejection speed and flow rate of the gas fuel.

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