Coal-fired unit mixed combustion biomass carbon reduction system, method and equipment

Abstract

The invention relates to the technical field of biomass blending combustion of thermal power generating units, in particular to a coal-fired unit biomass blending combustion carbon reduction system, method and equipment. The system comprises a crusher, a drying pipe and a fan mill which are sequentially connected with a biomass stock ground; a drying heat source of the drying pipe is from a dry bottom hopper of a coal-fired unit boiler; and the output end of the fan mill is connected with the fuel input end of the boiler. In the biomass blending combustion process, the biomass is preliminarily crushed by the crusher, so that the subsequent grinding energy consumption is reduced; the primarily crushed biomass is dried by using waste heat of a dry bottom hopper of a coal-fired unit boiler, and the surface of the primarily crushed biomass is carbonized to form a porous structure of which the internal part keeps fiber strength, so that a guarantee is provided for final crushing of the biomass; and the dry biomass with the carbonized surface is ground by the fan mill to reach the combustion particle size, so that the effective blending combustion of the biomass is realized. The problems that existing plate-shaped biomass is insufficient in combustion, large in energy consumption, low in efficiency and poor in safety are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass co - firing in thermal power units, and specifically to a carbon reduction system and method for co - firing biomass in coal - fired units, especially a carbon reduction system, method and equipment for co - firing biomass in coal - fired units based on high - temperature flue gas drying and carbonization and high - speed crushing. Background Technique

[0002] Biomass fuel is a technology that converts biomass materials into energy. It uses organic substances such as plants, animals, and microorganisms as raw materials, and through physical, chemical, or biological conversion methods, produces energy products that can replace traditional fossil fuels. Biomass fuel comes from the photosynthesis of plants, and like wind energy, solar energy, etc., it belongs to renewable energy. The raw material sources are extensive, including agricultural waste, forestry residues, municipal organic waste, etc. The raw material cost is relatively low, and the production technology is relatively mature, which can reduce the energy use cost. Moreover, the carbon dioxide absorbed by biomass during growth is approximately equal to the carbon dioxide released during its combustion, which helps to reduce greenhouse gas emissions. Therefore, biomass fuel has the characteristics of being renewable, low - carbon emission, and wide resource distribution, and is one of the important directions for current energy transformation and response to climate change, and has broad application prospects in the civil, industrial, and transportation fields.

[0003] The technology of biomass co - firing in thermal power units is a technology that mixes biomass fuel and coal in a certain proportion and sends them into the boiler of a thermal power unit for co - combustion and power generation. This technology replaces part of the coal with biomass, and utilizes the renewable and low - carbon characteristics of biomass fuel to achieve the low - carbon transformation of thermal power units, while improving the energy utilization efficiency, reducing fossil energy consumption and pollutant emissions.

[0004] At present, biomass raw materials are mainly divided into straw - like and wood - board - like. Among them, straw - like raw materials are rich in cellulose, hemicellulose, and lignin, and have a relatively high calorific value for combustion. They are mostly crushed to a particle size of 3 - 6 mm in stages and then sent into the boiler for combustion. However, plate - like biomass has a large density and a thick size. If it is directly sent into the boiler for combustion by the above - mentioned crushing method, the existing crushing process cannot achieve efficient crushing, resulting in non - compliant combustion particle size, a large increase in unit energy consumption, insufficient drying, insufficient carbonization synergy with traditional segmented carbonization treatment, high energy consumption, low efficiency, and poor safety. Summary of the Invention

[0005] Aiming at the problems of insufficient combustion, high energy consumption, low efficiency, and poor safety of plate - like biomass in the prior art, the present invention provides a carbon reduction system, method and equipment for co - firing biomass in coal - fired units.

[0006] To achieve the above - mentioned purpose, the present invention adopts the following technical solutions: The present invention provides a carbon reduction system for co-firing biomass in a coal-fired unit, which includes a crusher, a drying pipe, and a fan mill that are sequentially connected to a biomass storage yard; the drying heat source of the drying pipe comes from the cold ash hopper of the coal-fired unit boiler; the output end of the fan mill is connected to the fuel input end of the boiler.

[0007] Optionally, a biomass powder bin is arranged between the crusher and the drying pipe.

[0008] Optionally, the crusher is a serrated knife roll crusher, and a screen is arranged at the output end of the serrated knife roll crusher.

[0009] Optionally, the fan mill is equipped with a dynamic separator.

[0010] Optionally, the drying pipe is made of 316L stainless steel.

[0011] Optionally, a cyclone dust removal device is arranged at the flue gas output end of the cold ash hopper.

[0012] Optionally, the rotational speed of the fan mill is 2800 - 3500 rmp.

[0013] A biomass co-firing device for a coal-fired unit includes the above-mentioned carbon reduction system for co-firing biomass in a coal-fired unit.

[0014] The present invention also provides a carbon reduction method using the above-mentioned carbon reduction system for co-firing biomass in a coal-fired unit, which includes: Transport the biomass from the biomass storage yard to the crusher for shearing and crushing to less than 10 mm to obtain pre-crushed biomass; Transport the pre-crushed biomass to the drying pipe, and introduce the high-temperature flue gas produced by the cold ash hopper to the drying pipe to contact the pre-crushed biomass in a countercurrent manner to obtain dried and surface-carbonized biomass; Introduce the dried and surface-carbonized biomass into the fan mill for secondary pulverization to less than 1 mm to obtain biomass particles; Introduce the biomass particles into the boiler for combustion to complete the carbon reduction process.

[0015] Optionally, the temperature of the high-temperature flue gas produced by the cold ash hopper is 600°C - 700°C, and the residence time of the high-temperature flue gas in the drying pipe is greater than or equal to 10 s.

[0016] Compared with the prior art, the present invention has the following beneficial effects: A carbon reduction system for co-firing biomass in a coal-fired unit of the present invention includes a crusher, a drying pipe, and a fan mill that are sequentially connected to a biomass storage yard; the drying heat source of the drying pipe comes from the cold ash hopper of the coal-fired unit boiler; the output end of the fan mill is connected to the boiler fuel input end. During the process of biomass co-firing, first, the biomass is preliminarily crushed by the crusher to reduce the subsequent grinding energy consumption; then, the waste heat of the cold ash hopper of the coal-fired unit boiler is used to dry the preliminarily crushed biomass, and the surface of the preliminarily crushed biomass is carbonized to form a porous structure that maintains the fiber strength inside, thereby providing guarantee for the final crushing of the biomass; finally, the dried and surface-carbonized biomass is ground by the fan mill to easily reach the combustion particle size, so as to achieve the effective co-firing of biomass, with high co-firing efficiency, and the whole drying and carbonization are synchronous processes, fully utilizing the flue gas waste heat of the cold ash hopper, with high waste heat recovery rate and low energy consumption. In addition, the flue gas waste heat of the cold ash hopper and the setting of the drying pipe provide a sealed low-oxygen environment for the synchronous carbonization and drying process of biomass, which can effectively eliminate the risk of dust explosion and has higher safety. Compared with the traditional crushing and combustion method, the boiler combustion efficiency is increased by 10% - 15% due to the smaller pulverization particle size of the secondary fan mill, and the carbon content of fly ash is reduced to less than 3%; compared with the traditional drying and carbonization method, the comprehensive energy consumption is reduced by more than 40%. The system has a simple structure, forms a continuous processing chain of "crushing bin - drying pipe - fan mill - co-firing", occupies a small area, has a low transformation cost and small energy consumption loss, realizes the high-efficiency, safety and energy-saving of biomass co-firing, and has significant engineering application value.

[0017] A biomass powder bin is arranged between the crusher and the drying pipe. As an intermediate storage device, the biomass powder bin can balance the material transportation rate between the crusher and the drying pipe, avoid production discontinuity problems caused by the intermittent operation of the crusher or the fluctuation of the processing capacity of the drying pipe. At the same time, the crushed biomass can be temporarily stored in the powder bin to avoid the forced shutdown of the crusher due to downstream equipment failures or maintenance, and improve the equipment utilization rate.

[0018] The crusher is a saw-tooth knife roll crusher, and a screen is arranged at the output end of the saw-tooth knife roll crusher. The knife roll of the saw-tooth knife roll crusher adopts a saw-tooth structure, which can efficiently shear and tear high-fiber biomass (plate-shaped biomass), avoiding the blockage problem caused by fiber entanglement in the traditional hammer crusher. The setting of the screen at the output end can ensure that the crushed biomass particles are uniform, avoid oversized lumps from entering the subsequent drying pipe or fan mill, reduce equipment wear and energy consumption; at the same time, the screen directly separates qualified particles from unfully crushed materials, and the latter can be returned to the crusher for secondary treatment, reducing the ineffective energy consumption of the drying pipe and the fan mill.

[0019] The fan mill is equipped with a dynamic separator. The dynamic separator can adjust the rotor speed or blade angle to control the fineness of the biomass powder in real time, and can meet the combustion requirements under different co-firing ratios.

[0020] The drying pipe is made of 316L stainless steel, which has high strength and corrosion resistance, and can still maintain the surface passivation film in a long-term high-temperature drying environment, reducing oxidation loss and extending service life.

[0021] A cyclone dust removal device is arranged at the flue gas output end of the cold ash hopper. Cyclone dust removal can efficiently capture the fly ash carried in the flue gas of the cold ash hopper, preventing ash from adhering to the surface of biomass after entering the drying pipe and affecting the drying heat transfer efficiency. After dust removal, the dust content of the flue gas is reduced, reducing pipeline wear and heat transfer surface pollution, and ensuring the long-term stable operation of the drying pipe.

[0022] The rotational speed of the fan mill is 2800 - 3500 rmp. This rotational speed can effectively shear and tear fibers, overcoming the problem of insufficient grinding of biomass by traditional low-speed coal mills, and ensuring that the particle fineness meets the combustion requirements.

[0023] The present invention provides a biomass co-firing device for a coal-fired unit, including the above-mentioned biomass co-firing and carbon reduction system for a coal-fired unit. This device highly integrates a carbon reduction system of "biomass pre-crushing - drying and carbonization synergy - deep crushing and grinding" and has characteristics such as high combustion efficiency, low energy consumption, long service life, economy and environmental protection. It provides a "plug and play" biomass co-firing solution for the low-carbon transformation of coal-fired units and has broad industrial application prospects.

[0024] The present invention also provides a carbon reduction method using the above-mentioned biomass co-firing and carbon reduction system for a coal-fired unit. This method first transports biomass from the biomass yard to a crusher for shear crushing to less than 10 mm to obtain pre-crushed biomass. Then, the pre-crushed biomass is transported to the drying pipe, and the high-temperature flue gas produced by the cold ash hopper is led to the drying pipe to contact the pre-crushed biomass countercurrently to obtain dried and surface-carbonized biomass. Finally, the dried and surface-carbonized biomass is introduced into the fan mill for secondary crushing to less than 1 mm to obtain biomass particles and introduced into the boiler for combustion, completing the carbon reduction process. This method first coarsely crushes to less than 10 mm to reduce the subsequent drying / grinding load, saving 25% - 30% of energy compared with direct fine grinding. Then, the waste heat of the cold ash hopper flue gas is used for gradient drying and surface carbonization synergy of the pre-crushed biomass to quickly evaporate the internal moisture of the pre-crushed biomass, and at the same time, its surface carbonization enhances the hydrophobicity of the biomass, reducing the fiber toughness during grinding, thereby reducing the energy consumption of the fan mill. Finally, the fan mill is used to further crush and refine the particle size of the dried and surface-carbonized biomass to make the particle size less than 1 mm, increasing the combustion reaction area, and thus increasing the combustion efficiency, so as to achieve high-efficiency, low-energy-consumption, and high-safety biomass co-firing. The method is simple and easy to operate, providing technical support for the low-carbon transformation of coal-fired units.

[0025] The high-temperature flue gas produced by the cold ash hopper has a temperature of 600°C to 700°C, and the residence time of the high-temperature flue gas in the drying pipe is greater than or equal to 10 s, which can effectively reduce the moisture content of biomass and carbonize the surface of biomass, improving the brittleness of biomass and providing the basis and guarantee for subsequent deep grinding. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of a biomass co-firing carbon reduction system for a coal-fired unit of the present invention.

[0027] Figure 2 It is a flowchart of a method for reducing carbon by co-firing biomass in a coal-fired unit of the present invention.

[0028] Among them, 1-biomass storage yard, 2-crusher, 3-biomass powder bin, 4-drying pipe, 5-fan mill, 6-cold ash hopper. Detailed Embodiments

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0032] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0033] In addition, when the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0034] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, when terms such as "set", "installed", "connected", and "connected" appear, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0035] The following further elaborates on the present invention in conjunction with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0036] Aiming at the problems that the existing crushing process cannot achieve efficient crushing of wood-based panels, has low crushing efficiency and is easy to jam, has uneven particle size distribution, and affects the subsequent combustion efficiency, the traditional hot air drying has high energy consumption, and the moisture content of biomass fluctuates greatly, which easily leads to unstable boiler combustion, the problems that carbonization and drying are separated in the prior art, the process is complex, and the carbonization temperature control is inaccurate, resulting in limited increase in fuel calorific value, and the problem that the high oxygen content in the high-temperature flue gas during the traditional drying process is prone to cause the risk of biomass dust explosion, the present invention provides a coal-fired power unit co-firing biomass carbon reduction system. See Figure 1 The coal-fired power unit co-firing biomass carbon reduction system includes a crusher 2, a drying pipe 4, and a fan mill 5 that are sequentially connected to the biomass storage yard 1; the drying heat source of the drying pipe 4 comes from the cold ash hopper 6 of the coal-fired power unit boiler; the output end of the fan mill 5 is connected to the boiler fuel input end.

[0037] In the process of biomass blending, the biomass is firstly crushed by the crusher 2 to reduce the subsequent grinding energy consumption; then, the waste heat of the cold ash hopper 6 of the coal-fired unit boiler is used to input the initially crushed biomass into the drying tube 4 for drying, and the surface of the initially crushed biomass is carbonized to form a porous structure that maintains the fiber strength inside, thereby providing a guarantee for the final crushing of the biomass; finally, the dried and surface carbonized biomass is ground by the fan mill 5 to easily reach the combustion particle size, thereby achieving effective biomass blending, with high blending efficiency, and the entire drying and carbonization is a synchronous process, which fully utilizes the flue gas waste heat of the cold ash hopper, has a high waste heat recovery rate and low energy consumption. In addition, the coordinated setting of the flue gas waste heat of the cold ash hopper 6 and the drying tube 4 provides a closed low-oxygen environment for the synchronous carbonization and drying process of the biomass, which can effectively eliminate the risk of dust explosion and has higher safety. Compared with the traditional crushing and combustion method, the secondary fan mill has a smaller crushing particle size, which increases the boiler combustion efficiency by 10% to 15%, and reduces the fly ash carbon content to below 3%. Compared with the traditional drying and carbonization method, the comprehensive energy consumption is reduced by more than 40%. The system has a simple structure, forming a continuous processing chain of "crushing bin - drying tube - fan mill - blending". The equipment occupies a small area, has low transformation cost and small energy loss, and realizes the high efficiency, safety and energy saving of biomass blending, which has significant engineering application value.

[0038] Example 1 See also Figure 1 The present invention provides a carbon reduction system for biomass blending in coal-fired units, comprising a crusher 2, a biomass powder bin 3, a drying tube 4 and a fan mill 5 connected in sequence to a biomass material field 1; the drying heat source of the drying tube 4 comes from the cold ash hopper 6 of the boiler of the coal-fired unit; the output end of the fan mill 5 is connected to the boiler fuel input end. Among them, the biomass powder bin 3 serves as an intermediate storage device, which can balance the material conveying rate between the crusher 2 and the drying tube 4, avoiding production discontinuity problems caused by intermittent operation of the crusher 2 or fluctuations in the processing capacity of the drying tube. At the same time, the crushed biomass can be temporarily stored in the biomass powder bin 3, avoiding the crusher 2 being forced to shut down due to downstream equipment failure or maintenance, thereby improving equipment utilization.

[0039] In view of the problem that the traditional crushing process cannot effectively crush plate-shaped biomass, resulting in non-compliant biomass combustion particles, the present invention designs to first preliminarily crush the biomass to make it less than 10 mm, and then utilize the waste heat of the boiler cold ash hopper 6 to synergistically dry and carbonize the preliminarily crushed biomass, making the preliminarily crushed biomass dry and brittle, facilitating the improvement of subsequent combustion efficiency and laying a foundation for further pulverization of the biomass. Then, the dried and embrittled biomass is sent to the fan mill 5 for pulverization to make its particle size less than 1 mm, providing a larger specific surface area for subsequent co-firing. At the same time, the utilization of the waste heat of the boiler cold ash hopper 6 not only realizes the stepped utilization of energy, but also the oxygen content in the flue gas waste heat is <6%, which can effectively avoid the risk of dust explosion, not only improving the energy utilization efficiency of the system, but also having the characteristics of low energy consumption and good safety.

[0040] Example 2 See Figure 1 , the present invention provides a coal-fired unit biomass co-firing carbon reduction system, including a crusher 2, a biomass powder silo 3, a drying pipe 4, and a fan mill 5 that are sequentially connected to the biomass storage yard 1; The crusher 2 is a serrated knife roll crusher, and a screen is arranged at the output end of the serrated knife roll crusher. The screen can dynamically adjust the particle size distribution to avoid material jamming problems, and after vibration screening, it is temporarily stored in the biomass powder silo 3; The drying heat source of the drying pipe 4 comes from the cold ash hopper 6 of the coal-fired unit boiler; the length of the drying pipe 4 is 10 - 15 m, the inner diameter is 0.8 - 1.2 m, and the material is high-temperature resistant stainless steel (316L stainless steel); The output end of the fan mill 5 is connected to the boiler fuel input end. The fan mill 5 is equipped with a dynamic separator. The dynamic separator can adjust the fineness of the biomass powder in real time by adjusting the rotor speed or blade angle, and can meet the combustion requirements under different co-firing ratios. It is used to adjust the crushing gap of the fan mill 5 according to the surface carbonization degree of the biomass, generally 0.5 - 2 mm, and the rotation speed of the fan mill 5 is 2800 - 3500 rpm.

[0041] The flue gas flow rate of the cold ash hopper 6 entering the drying pipe 4 is 8 - 12 m / s; preferably, a cyclone dust removal device is arranged at the flue gas outlet of the cold ash hopper 6; Compared with the traditional co-firing system, the fuel particle size of the coal-fired unit biomass co-firing carbon reduction system of the present invention is ≤1 mm, the boiler thermal efficiency is increased by 10% - 15%, the carbon content in the fly ash is reduced to less than 3%, the comprehensive energy consumption of drying and carbonization is reduced by more than 40% by utilizing the boiler flue gas waste heat, and the low-oxygen environment (O2 < 6%) of the flue gas waste heat and the design of the closed drying pipe 4 eliminate the risk of dust explosion and have better safety.

[0042] The present invention provides a biomass co-firing device for coal-fired units, including the above-mentioned biomass co-firing and carbon reduction system for coal-fired units. This device highly integrates a carbon reduction system that combines "biomass pre-crushing - drying, carbonization synergy - deep crushing and grinding" in one, and has the characteristics of high combustion efficiency, low energy consumption, long service life, economic and environmental protection, etc. It provides a "plug and play" biomass co-firing solution for the low-carbon transformation of coal-fired units, and has broad industrial application prospects.

[0043] See Figure 2 , the present invention also provides a carbon reduction method using the above-mentioned biomass co-firing and carbon reduction system for coal-fired units, including: S1: Convey biomass from the biomass storage yard to the crusher 2 for shearing and crushing to less than 10 mm to obtain pre-crushed biomass; the crusher 2 adopts a combination of a serrated knife roller and a screen, which is adapted to the shape of plate-like materials; convey woody and plate-like biomass to the serrated knife roller crusher, break the plate-like materials to within 10 mm through shear force, and the screen dynamically adjusts the particle size distribution to avoid material jamming problems. After vibrating screening, it is temporarily stored in the biomass powder bin.

[0044] S2: Convey the pre-crushed biomass to the drying pipe 4, and introduce the high-temperature flue gas generated by the cold ash hopper 6 to the drying pipe 4 to contact the pre-crushed biomass in a countercurrent manner to obtain dried and surface-carbonized biomass; preferably, the temperature of the high-temperature flue gas generated by the cold ash hopper 6 is 600°C - 700°C, and the residence time of the high-temperature flue gas in the drying pipe 4 is greater than or equal to 10 s; after the high-temperature flue gas generated by the cold ash hopper 6 is subjected to cyclone dust removal, the biomass particles contact the high-temperature flue gas in the drying pipe 4 in a countercurrent manner, and the residence time of the high-temperature flue gas in the drying pipe 4 is greater than or equal to 10 s. At this time, the moisture content of the biomass particles drops from 25% - 35% to less than 10%, and at the same time, a carbonization reaction occurs on the surface to form a porous structure, and the internal fiber strength is maintained, which is convenient for subsequent crushing. In this step, the high-temperature flue gas (oxygen content < 6%) at 600°C - 700°C discharged from the cold ash hopper 6 of the boiler is used as a heat source to synchronously complete drying and carbonization in the drying pipe, realizing efficient waste heat recovery and reducing external energy consumption; S3: Introduce the dried and surface-carbonized biomass into the fan mill 5 for secondary crushing to less than 1 mm to obtain biomass particles. More than 90% of the biomass after secondary crushing by the fan mill 5 is <1 mm, and the particle size distribution is concentrated, laying a foundation for subsequent sufficient combustion. This step uses the impact and shear force of the high-speed rotating blades to crush the biomass particles, making more than 90% of the biomass particle size <1 mm. Due to the significant increase in brittleness of the dried and carbonized particles on the surface, the rotational speed of the fan mill can be reduced to 2500 rpm, saving more than 30% of energy. The crushed fuel is sent into the boiler for combustion through the primary air duct. Due to the small particle size and fast release of volatile matter, the ignition temperature is reduced by 50°C to 80°C, and the burnout rate is increased to more than 95%. A dynamic separator is added to the fan mill 5 to adjust the crushing gap (0.5 - 2 mm) in real time according to the degree of carbonization, ensuring the uniformity of particle size and avoiding the decline in crushing efficiency caused by fluctuations in material properties in the prior art.

[0045] S4: Introduce the biomass particles into the boiler for combustion to complete the carbon reduction process.

[0046] In summary, the present invention provides a coal-fired power unit biomass co-firing carbon reduction system, method and equipment, including a crusher, a drying pipe and a fan mill connected in sequence with a biomass yard; the drying heat source of the drying pipe comes from the cold ash hopper of the coal-fired power unit boiler; the output end of the fan mill is connected to the boiler fuel input end, forming a continuous processing chain of "crushing bin - drying pipe - fan mill - co-firing", realizing the high-efficiency, safety and energy-saving of biomass co-firing, and having significant engineering application value.

[0047] The above are only the preferred embodiments of the present invention and are not used to limit the technical solutions of the present invention. Those skilled in the art should understand that without departing from the spirit and principles of the present invention, the technical solutions can be subject to several simple modifications and substitutions, and these modifications and substitutions also fall within the protection scope covered by the claims.

Claims

1. A carbon reduction system for co-firing biomass in a coal-fired unit, characterized in that, It includes a crusher, a drying pipe and a fan mill that are sequentially connected to the biomass storage yard; the drying heat source of the drying pipe comes from the cold ash hopper of the coal-fired unit boiler; the output end of the fan mill is connected to the boiler fuel input end.

2. The biomass co-firing carbon reduction system for a coal-fired unit according to claim 1, characterized in that A biomass powder bin is arranged between the crusher and the drying pipe.

3. The biomass co-firing carbon reduction system for coal-fired units according to claim 1, wherein, The crusher is a serrated knife roll crusher, and a screen is arranged at the output end of the serrated knife roll crusher.

4. The biomass co-firing carbon reduction system for coal-fired units according to claim 3, wherein, The fan mill is equipped with a dynamic separator.

5. The biomass co-firing carbon reduction system for coal-fired units according to claim 1, wherein The drying pipe is made of 316L stainless steel.

6. The biomass co-firing carbon reduction system for a coal-fired unit according to claim 1, characterized in that, A cyclone dust removal device is arranged at the flue gas output end of the cold ash hopper.

7. The biomass co-firing carbon reduction system for coal-fired units according to claim 1, wherein, The rotation speed of the fan mill is 2800 - 3500 rmp.

8. A biomass co-firing device for a coal-fired unit, characterized in that, It includes the coal-fired unit biomass co-firing carbon reduction system according to any one of claims 1 - 7.

9. A carbon reduction method using the carbon reduction system for co-firing biomass in the coal-fired unit described in claim 1, characterized in that, It includes: Transport the biomass from the biomass storage yard to the crusher for shearing and crushing to less than 10 mm to obtain pre-crushed biomass; Transport the pre-crushed biomass to the drying pipe, and introduce the high-temperature flue gas produced by the cold ash hopper to the drying pipe to make it flow countercurrently to the pre-crushed biomass to obtain dried and surface-carbonized biomass; Introduce the dried and surface-carbonized biomass into the fan mill for secondary pulverization to less than 1 mm to obtain biomass particles; Introduce the biomass particles into the boiler for combustion to complete the carbon reduction process.

10. The method for reducing carbon emissions by co-firing biomass in a coal-fired unit according to claim 9, wherein The temperature of the high-temperature flue gas produced by the cold ash hopper is 600°C - 700°C, and the residence time of the high-temperature flue gas in the drying pipe is greater than or equal to 10 s.

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