Biomass co-grinding blending combustion coal-fired unit and power generation system

Abstract

The embodiment of the invention discloses a biomass co-grinding blending combustion coal-fired unit and a power generation system. The system comprises a first-stage crusher, a second-stage crusher, a third-stage crusher, a fourth-stage crusher, a fourth-stage crusher and a fifth-stage crusher, the second-stage crusher receives the mixture of the coal and the biomass after the first-stage crushing, and performs second-stage crushing on the mixture; wherein the particle size of the mixture obtained after secondary crushing is smaller than that of the mixture obtained after primary crushing; a water spray head is used for spraying the mixture subjected to secondary crushing; the raw coal conveyor is used for conveying the mixture subjected to spraying treatment to a raw coal bunker; the material uniformizing device receives the mixture in the raw coal bunker and distributes the mixture for each coal mill; the air conveying device outputs cold and hot mixed air to the mixed material distributed in the material uniformizing device, and the mixed material is conveyed to the corresponding coal mill; and the coal mill crushes the mixture and conveys the crushed mixture to a hearth of the boiler. The continuous feeding of the fuel is realized, the uniformity of the fuel and the combustion stability are improved, the flying dust is reduced, and the output and the operation efficiency of the coal mill are improved.

Description

Technical Field

[0001] The invention relates to the technical field of biomass combustion, and in particular to a biomass co-grinding and blending coal-fired unit and a power generation system. Background Art

[0002] Biomass co-combustion is divided into three types: direct co-combustion, indirect co-combustion and parallel combustion. Biomass co-grinding and co-combustion technology is a type of direct co-combustion method, which involves mixing and grinding biomass fuel and coal in a coal mill, and then sending the mixed fuel into the furnace for combustion. This method requires less modification to the original system, has relatively low modification costs, and is simple to operate. It is suitable for existing coal-fired power plants, and co-grinding and co-combustion of biomass and coal can be achieved through simple modifications. This technology can significantly reduce the carbon emission level of coal-fired power and promote emission reduction from coal-fired power sources.

[0003] The biomass is ground by the coal mill of the existing boiler and then sent to the furnace for combustion. The blending ratio can reach up to 10% without major equipment modification. However, the different characteristics of biomass and coal will reduce the operating efficiency of the original pulverizing system, and the combustion conditions are poor, the flame stability and heat transfer characteristics are not good, and the risks of slagging, ash accumulation and corrosion are easily increased. At the same time, the continuous and stable supply of biomass fuel is one of the keys to ensure the smooth blending of biomass, especially when dealing with sticky or easily agglomerated biomass materials, which are prone to blockage. Summary of the invention

[0004] The present invention provides a biomass co-grinding and blended combustion coal-fired unit and a power generation system, which realizes continuous feeding of fuel, improves the uniformity of fuel and the stability of combustion, reduces dust, and improves the output and operation efficiency of the coal mill.

[0005] According to one aspect of the present invention, there is provided a biomass co-grinding and coal-fired unit, comprising:

[0006] A primary crusher, a secondary crusher, a water sprinkler, a raw coal conveyor, a raw coal bunker, a screeder, at least one coal mill, an air conveying device and a boiler;

[0007] The primary crusher is used to receive coal and biomass and perform primary crushing on the coal and biomass;

[0008] The secondary crusher is used to receive the mixture of coal and biomass after primary crushing and perform secondary crushing on the mixture; wherein the particle size of the mixture after secondary crushing is smaller than the particle size of the mixture after primary crushing;

[0009] The water nozzle is used to spray the mixed material after secondary crushing;

[0010] The raw coal conveyor is used to transfer the mixed material after spraying to the raw coal bunker;

[0011] The homogenizer is used to receive the mixed material in the raw coal bunker and distribute the mixed material to each coal mill;

[0012] The air delivery device is used to output hot and cold mixed air to the mixed material distributed in the material distributor, and transport the mixed material to the corresponding coal mill;

[0013] The coal mill is used to crush the mixed material and then transport it to the furnace of the boiler.

[0014] Optionally, the particle size of the mixed material after the primary crushing is less than 20 mm;

[0015] The particle size of the mixed material after secondary crushing is less than 10mm.

[0016] Optionally, the mass proportion of biomass in the mixed material does not exceed 20%.

[0017] Optionally, the air delivery device includes an air preheater and a primary fan;

[0018] The first air outlet of the primary fan is connected to the inlet of the air preheater through a first pipeline, and the outlet of the air preheater and the second air outlet of the primary fan are connected to the air inlet of the sparger through a second pipeline.

[0019] Optionally, the biomass co-grinding and co-firing coal-fired unit includes a plurality of coal mills;

[0020] A plurality of coal mills are arranged in sequence along the height direction of the furnace of the boiler;

[0021] The number of coal mills turned on varies depending on the boiler's workload.

[0022] Optionally, when the boiler operates at a first load, at least two coal mills located at the top layer among the multiple coal mills are turned on, and when the boiler operates at a second load, all the multiple coal mills are turned on; wherein the first load is less than the second load.

[0023] Optionally, the biomass co-grinding and coal-fired unit also includes: a raw coal shed, a biomass bin and a belt conveyor;

[0024] The raw coal shed is used to store coal;

[0025] The biomass silo is used to store biomass;

[0026] The belt conveyor is used to transport the coal from the raw coal shed and the biomass from the biomass bin to the primary crusher.

[0027] According to another aspect of the present invention, there is provided a power generation system, comprising the biomass co-grinding and co-firing coal-fired unit according to any embodiment of the present invention.

[0028] The biomass co-grinding and blending coal-fired unit provided in the embodiment of the present invention comprises a primary crusher, a secondary crusher, a water nozzle, a raw coal conveyor, a raw coal bin, a homogenizer, at least one coal mill, an air conveying device and a boiler; the primary crusher is used to receive coal and biomass, and perform primary crushing on the coal and biomass; the secondary crusher is used to receive the mixture of coal and biomass after primary crushing, and perform secondary crushing on the mixture; wherein the particle size of the mixture after secondary crushing is smaller than the particle size of the mixture after primary crushing. The water nozzle is used to spray the mixture after secondary crushing; the dust caused by biomass blending is reduced, and the environment is protected. The raw coal conveyor is used to transfer the sprayed mixture to the raw coal bin; the homogenizer is used to receive the mixture in the raw coal bin and distribute the mixture to each coal mill; the air conveying device is used to output hot and cold mixed air to the distributed mixture in the homogenizer, and transport the mixture to the corresponding coal mill; the coal mill is used to crush the mixture and transport it to the furnace of the boiler. By subjecting biomass raw materials and coal to primary and secondary crushing treatment, the biomass and coal are refined before entering the conveying pipeline, avoiding blockage in the biomass material conveying process, and realizing continuous feeding of fuel in the biomass blending process. At the same time, the biomass raw materials and raw coal can be fully mixed in the two-stage crushing process, improving the uniformity of the fuel of the biomass blending unit and improving the stability of the fuel entering the furnace for combustion. After the biomass and coal powder are crushed at the secondary level, water nozzles are used to spray water to prevent dust, reduce environmental pollution, and prevent spontaneous combustion during the fuel transportation process; cold and hot primary mixed air is used to pre-dry the fuel to enter the furnace, and the particle size of the mixed fuel is controlled through two-stage crushing. At the same time, a homogenizer is used to evenly distribute the refined mixed fuel to each coal mill, which improves the output and operation efficiency of the coal mill during the biomass blending process.

[0029] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 It is a module schematic diagram of a biomass co-grinding and co-firing coal-fired unit provided in an embodiment of the present invention.

[0032] Figure 2 It is a module schematic diagram of another biomass co-grinding and co-firing coal-fired unit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] The embodiment of the present invention provides a biomass co-grinding and coal-fired unit, Figure 1 Schematic diagram of a biomass co-grinding and coal-fired unit provided by an embodiment of the present invention. Figure 1 , biomass co-grinding and coal-fired units include:

[0036] A primary crusher 11, a secondary crusher 12, a water nozzle 13, a raw coal conveyor 14, a raw coal bin 15, a sizing machine 16, at least one coal mill 18, an air conveying device 17 and a boiler 19;

[0037] The primary crusher 11 is used to receive coal and biomass and perform primary crushing on the coal and biomass;

[0038] The secondary crusher 12 is used to receive the mixture of coal and biomass after primary crushing and perform secondary crushing on the mixture; wherein the particle size of the mixture after secondary crushing is smaller than the particle size of the mixture after primary crushing;

[0039] The water nozzle 13 is used to spray the mixed material after secondary crushing;

[0040] The raw coal conveyor 14 is used to transfer the sprayed mixed material to the raw coal bin;

[0041] The smelter 16 is used to receive the mixed material in the raw coal bin and distribute the mixed material to each coal mill 18;

[0042] The air delivery device 17 is used to output hot and cold mixed air to the mixed material distributed in the sparger 16, and transport the mixed material to the corresponding coal mill 18;

[0043] The coal mill 18 is used to pulverize the mixed material and then transport it to the furnace of the boiler 19 .

[0044] Specifically, the coal and biomass raw materials are conveyed to the primary crusher 11 through a belt conveyor. The primary crusher 11 performs preliminary crushing on the coal and biomass raw materials to a fineness of less than 20 mm. The mixture after primary crushing continues to enter the secondary crusher 12. The secondary crusher 12 further crushes the mixture to less than 10 mm. Before the secondary crushed mixture enters the raw coal conveyor 14, it first enters the water nozzle 13 area. The water nozzle 13 sprays the mixture. The sprayed mixture is transported by the raw coal conveyor 14 to the raw coal bin 15 for storage. Before the mixture enters the coal mill 18 from the raw coal bin 15, it is first evenly distributed by the sizing device 16. The air delivery device 17 outputs cold and hot mixed air to the distributed mixture in the sizing device 16, and the mixture is transported to the corresponding coal mill 18. The coal mill 18 crushes the mixture and then transports it to the furnace of the boiler 19 to mix with air and burn it to generate steam for power generation.

[0045] The biomass co-grinding and blending coal-fired unit provided in the embodiment of the present invention comprises a primary crusher 11, a secondary crusher 12, a water nozzle 13, a raw coal conveyor 14, a raw coal bin 15, a material leveler 16, at least one coal mill 18, an air conveying device 17 and a boiler 19; the primary crusher 11 is used to receive coal and biomass, and perform primary crushing on the coal and biomass; the secondary crusher 12 is used to receive the mixture of coal and biomass after primary crushing, and perform secondary crushing on the mixture; wherein, the particle size of the mixture after secondary crushing is smaller than the particle size of the mixture after primary crushing. The water nozzle 13 is used to spray the mixture after secondary crushing; the dust caused by the blending of biomass is reduced, and the environment is protected. The raw coal conveyor 14 is used to transfer the mixture after spraying to the raw coal bin 15; the sparger 16 is used to receive the mixture in the raw coal bin 15 and distribute the mixture to each coal mill 18; the air delivery device 17 is used to output hot and cold mixed air to the distributed mixture in the sparger 16, and transport the mixture to the corresponding coal mill 18; the coal mill 18 is used to crush the mixture and then transport it to the furnace of the boiler 19. By subjecting the biomass raw materials and coal to primary and secondary crushing treatments together, the biomass and coal are refined before entering the conveying pipeline, avoiding blockage in the biomass material conveying process, and realizing continuous feeding of fuel in the biomass blending process. At the same time, the biomass raw materials and raw coal can be fully mixed in the two-stage crushing process, which improves the uniformity of the fuel of the biomass blending unit and improves the stability of the fuel entering the furnace for combustion. After the biomass and coal powder are crushed at the second level, water nozzles are used to spray water to prevent dust, reduce environmental pollution and prevent spontaneous combustion during the fuel transportation process; cold and hot primary mixed air is used to pre-dry the fuel entering the furnace, and the particle size of the mixed fuel is controlled through two-stage crushing. At the same time, a homogenizer is used to evenly distribute the refined mixed fuel to each pulverizer, which improves the output and operation efficiency of the pulverizer during biomass blending.

[0046] Optionally, the particle size of the mixed material after the primary crushing is less than 20 mm;

[0047] The particle size of the mixed material after secondary crushing is less than 10mm.

[0048] Specifically, the particle size of the mixed material after the first-stage crushing is less than 20mm; the particle size of the mixed material after the second-stage crushing is less than 10mm. Through two-stage crushing, the biomass and coal can be better refined, avoiding blockage in the biomass material transportation process, and realizing continuous feeding of fuel in the biomass blending process. In addition, the biomass raw materials and raw coal can be fully mixed in the two-stage crushing process, improving the uniformity of the fuel of the biomass blending unit and improving the stability of the fuel entering the furnace for combustion.

[0049] Optionally, the mass proportion of biomass in the mixed material does not exceed 20%.

[0050] Specifically, during the mixed combustion of biomass and coal, the calorific value and combustion characteristics of biomass are different from those of coal. Controlling the proportion of biomass within 20% can ensure that the combustion performance of the mixture is relatively stable and avoid violent fluctuations during the combustion process. The combustion rate of biomass is usually higher than that of coal, but excessive biomass may lead to incomplete combustion. The appropriate biomass ratio helps to optimize the combustion process, improve combustion efficiency, and reduce unburned losses. Biomass may contain more ash and impurities, causing wear on equipment such as crushers and coal mills. Controlling the biomass ratio can reduce equipment wear, extend equipment service life, and improve the thermal efficiency and power generation efficiency of the boiler. As a renewable energy source, biomass is usually cheaper than coal. Controlling the biomass ratio can reduce raw material costs while ensuring combustion performance.

[0051] Figure 2 Schematic diagram of another biomass co-grinding and coal-fired unit provided by an embodiment of the present invention. Figure 2 , the air delivery device 17 includes an air preheater 21 and a primary fan 22;

[0052] The first air outlet of the primary fan 22 is connected to the inlet of the air preheater 21 through a first pipeline 23 , and the outlet of the air preheater 21 and the second air outlet of the primary fan 22 are connected to the air inlet of the sparger 16 through a second pipeline 24 .

[0053] Specifically, the primary fan 22 inhales cold air from the outside, and the cold air enters the first pipeline 23 through the first air outlet of the primary fan 22. The cold air entering the first pipeline 23 is transported from the inlet of the air preheater 21 to the air preheater 21. The cold air is preheated to a certain temperature by the air preheater 21, and the preheated hot air is discharged from the outlet of the air preheater 21. The second air outlet of the primary fan 22 blows out cold air again. The hot air and the cold air are combined to form a cold and hot primary mixed air, which is transported to the sparger 16 through the second pipeline 24. During the transportation process, part of the moisture in the fuel is dried at the same time, which improves the wear resistance and combustion stability of the fuel. By preheating the cold air, the temperature of the hot air entering the coal mill can be increased, the combustion speed of the fuel can be accelerated, and the combustion efficiency can be improved.

[0054] Optionally, the biomass co-grinding and co-firing coal-fired unit includes a plurality of coal mills 18;

[0055] A plurality of coal mills 18 are arranged in sequence along the height direction of the furnace of the boiler 19;

[0056] When the working load of the boiler 19 is different, the number of the coal mills 18 that are turned on is different.

[0057] Specifically, by adjusting the number of coal mills 18 that are opened, the fuel supply can be accurately controlled according to the actual working load of the boiler, ensuring the full combustion of the fuel in the furnace, reducing the loss of incomplete combustion of the fuel, reducing energy consumption in the power generation process, and improving combustion efficiency and energy utilization efficiency. By adjusting the number of coal mills 18 in operation according to changes in the load of the boiler 19, it is possible to quickly respond to load changes, meet the different demands of the power grid for power generation, and reduce the energy consumption and emissions of the system due to load fluctuations. By adjusting the number of coal mills 18 in operation, it is possible to ensure the stable operation of the boiler under different loads, reduce the system instability caused by load fluctuations, and improve the overall stability of the power generation system. The setting of multiple coal mills 18 can provide redundant backup. When a coal mill 18 fails, the standby coal mill 18 can be quickly started to maintain the normal operation of the system and enhance the reliability and safety of the power generation system.

[0058] Optionally, when the boiler 19 operates at a first load, at least two coal mills 18 located at the top layer among the multiple coal mills 18 are turned on, and when the boiler 19 operates at a second load, all of the multiple coal mills 18 are turned on; wherein the first load is less than the second load.

[0059] Among them, the at least two coal mills on the top layer are at least two coal mills arranged continuously from the highest point downwards.

[0060] Specifically, when the system detects that the boiler 19 is currently operating in a low-load state, the power plant operator automatically or manually selects at least two coal mills 18 arranged in a row from the highest point to the bottom to start. Starting the upper coal mill 18 and the corresponding upper burner can raise the center of the furnace flame and reduce the heat absorption of the furnace, thereby alleviating the reduction in furnace temperature caused by the load reduction. The mixed fuel of biomass and coal burns in the upper layer of the furnace, effectively reducing the emissions of nitrogen monoxide and nitrogen dioxide from the boiler. The system continuously monitors the load changes of the boiler 19 and the operating status of the coal mill 18 to ensure stable operation. When the system detects that the boiler load increases and reaches a high-load state, the system controls all coal mills 18 to start to provide more mixed fuel for combustion, realize a large amount of biomass blending, and meet the unit's carbon reduction requirements. After all the coal mills 18 are turned on, the system will adjust the coal supply and ventilation volume of each coal mill 18 according to the load changes and combustion efficiency to ensure the stable operation and efficient combustion of the boiler 19.

[0061] Optionally, the biomass co-grinding and co-firing coal-fired unit further includes: a raw coal shed 31, a biomass bin 32 and a belt conveyor 33;

[0062] The raw coal shed 31 is used to store coal;

[0063] The biomass bin 32 is used to store biomass;

[0064] The belt conveyor 33 is used to transport the coal in the raw coal shed 21 and the biomass in the biomass bin 32 to the primary crusher 11 .

[0065] Specifically, biomass, as a renewable energy source, produces relatively few pollutants when burned. By introducing biomass as fuel, the emission of pollutants generated during the power generation process can be reduced and environmental pollution can be reduced. The raw coal shed 31 and the biomass bin 32 are used to store coal and biomass, respectively. According to the power generation demand, by reasonably adjusting the ratio of coal and biomass, resources can be fully utilized to improve the power generation efficiency. When the system receives the start command, the belt conveyor 33 is started. The belt conveyor 33 transports the coal in the raw coal shed 31 and the biomass in the biomass bin 32 to the primary crusher 11 respectively. The primary crusher 11 begins to crush the fuel and crush it into a particle size suitable for combustion. As an automated conveying equipment, the belt conveyor 33 can efficiently and quickly transport the coal in the raw coal shed 31 and the biomass in the biomass bin 32 to the primary crusher 11, which not only reduces the labor intensity of manual handling, but also improves the conveying efficiency. Through the connection of the belt conveyor 33, the raw coal and biomass can be continuously and stably transported to the crusher for processing. The production process can be optimized and the operating efficiency of the entire power generation system can be improved.

[0066] According to another aspect of the present invention, there is provided a power generation system, comprising the biomass co-grinding and co-firing coal-fired unit according to any embodiment of the present invention.

[0067] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0068] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A biomass co-grinding and coal-fired unit, characterized in that: include: A primary crusher, a secondary crusher, a water sprinkler, a raw coal conveyor, a raw coal bunker, a screeder, at least one coal mill, an air conveying device and a boiler; The primary crusher is used to receive coal and biomass and perform primary crushing on the coal and biomass; The secondary crusher is used to receive the mixture of coal and biomass after primary crushing and perform secondary crushing on the mixture; wherein the particle size of the mixture after secondary crushing is smaller than the particle size of the mixture after primary crushing; The water nozzle is used to spray the mixed material after secondary crushing; The raw coal conveyor is used to transfer the mixed material after spraying to the raw coal bin; The material mixer is used to receive the mixed material in the raw coal bunker and distribute the mixed material to each coal mill; The air delivery device is used to output hot and cold mixed air to the mixed material distributed in the sparger, and transport the mixed material to the corresponding coal mill; The coal mill is used to crush the mixed material and then transport it to the furnace of the boiler.

2. The biomass co-grinding and coal-fired unit according to claim 1 is characterized in that: The particle size of the mixed material after primary crushing is less than 20 mm; The particle size of the mixed material after secondary crushing is less than 10mm.

3. The biomass co-grinding and coal-fired unit according to claim 1 is characterized in that: The mass proportion of biomass in the mixed material shall not exceed 20%.

4. The biomass co-grinding and coal-fired unit according to claim 1, characterized in that: The air delivery device includes an air preheater and a primary fan; The first air outlet of the primary fan is connected to the inlet of the air preheater through a first pipeline, and the outlet of the air preheater and the second air outlet of the primary fan are connected to the air inlet of the scrambler through a second pipeline.

5. The biomass co-grinding and coal-fired unit according to claim 1, characterized in that: The biomass co-grinding and co-firing coal-fired unit includes multiple coal mills; A plurality of coal mills are arranged in sequence along the height direction of the furnace of the boiler; When the working load of the boiler is different, the number of the coal mills turned on is different.

6. The biomass co-grinding and coal-fired unit according to claim 5, characterized in that: When the boiler operates at a first load, at least two of the plurality of coal mills located at the top layer are turned on, and when the boiler operates at a second load, all of the plurality of coal mills are turned on; wherein the first load is less than the second load.

7. The biomass co-grinding and coal-fired unit according to claim 1, characterized in that: Also includes: Raw coal shed, biomass silo and belt conveyor; The raw coal shed is used to store coal; The biomass bin is used to store biomass; The belt conveyor is used to transport the coal in the raw coal shed and the biomass in the biomass bin to the primary crusher.

8. A power generation system, characterized in that: A biomass co-grinding and coal-fired unit comprising the biomass co-grinding and coal-fired unit as described in any one of claims 1 to 7.

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