Boiler powder feeding system and method suitable for multiple fuels and flexible in operation

Abstract

The invention discloses a boiler powder feeding system and method suitable for multiple fuels and flexible in operation. The system comprises a boiler, and a plurality of element combustors and a plurality of pulverized coal combustors are arranged on the boiler; the element combustor supplies powder through a middle storage bin type pulverizing system, and the element combustor ignites fuel powder and then feeds the fuel powder into a boiler; the pulverized coal burner supplies pulverized coal through a direct blowing type pulverizing system and feeds the pulverized coal into the boiler, and the pulverized coal is ignited through flames in the boiler. The middle storage bin type pulverizing system comprises a pulverizer, a powder bin, a powder feeding fan and a distributor which are connected in sequence, and the distributor is connected with the element combustor through a pipeline; the problems of unit low-carbon fuel replacement, full-low-load stable combustion and rapid load change are solved, and efficient and stable operation of the boiler is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of boiler retrofitting technology, specifically to a boiler pulverizing system and method that is applicable to multiple fuels and operates flexibly. Background Technology

[0002] Upgrading the pulverizing system has always been an important aspect of improving the operational flexibility of thermal power units. Currently, there are two main types of boiler pulverizing systems: direct-fired pulverizing systems and intermediate storage pulverizing systems. The direct-fired pulverizing system operates by directly connecting the coal mill to the boiler burner, with pulverized coal being ground and then directly blown into the furnace for combustion via primary air, without any intermediate storage. In contrast, the intermediate storage pulverizing system first stores the pulverized coal prepared by the coal mill in an independent silo, and then feeds it into the burner as needed through a feeding device.

[0003] Currently, most mainstream coal-fired boilers use direct-fired pulverizing systems, which have inherent drawbacks when operating at low loads: the amount of pulverized coal at the mill outlet decreases, but the air volume remains essentially unchanged, resulting in a low primary air pulverized coal concentration, unstable burner ignition, decreased combustion efficiency, and even the risk of boiler flameout. When the boiler load increases, the load ramp-up rate cannot meet the requirements for rapid load increases due to limitations in the pulverizing system's capacity. This not only affects the unit's peak-shaving capacity but also hinders the implementation of co-firing with low-carbon fuels such as biomass. The co-firing of low-carbon fuels such as biomass requires addressing the issues of diverse sources (such as agricultural and forestry waste and biomass charcoal) and stable transportation, but existing systems lack a unified storage and flexible supply mechanism. Although intermediate storage pulverizing systems can partially alleviate these problems, their economic efficiency in modification and compatibility with multiple fuels are insufficient, increasing operational safety difficulties and economic costs. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a boiler pulverizing system and method that is applicable to multiple fuels and operates flexibly. It couples a direct-fired pulverizing system and an intermediate storage pulverizing system, solving the problems of low-carbon fuel substitution and full-load flexibility of the unit, and ensuring efficient and stable boiler operation.

[0005] The technical solution of the present invention is as follows: In a first aspect of the invention, a boiler pulverizing system suitable for multiple fuels and flexible operation is provided, comprising a boiler equipped with multiple primary burners and multiple pulverized coal burners; the primary burners are supplied with pulverized coal through an intermediate storage pulverizing system, wherein the primary burners ignite the pulverized coal before sending it into the boiler; the pulverized coal burners are supplied with pulverized coal through a direct-fired pulverizing system, wherein the pulverized coal burners send the pulverized coal into the boiler and ignite it through a flame inside the boiler; the intermediate storage pulverizing system includes a grinding mill, a pulverized coal silo, a pulverized coal feeding fan, and a distributor connected in sequence, wherein the distributor is connected to the primary burners through pipelines.

[0006] In some embodiments of the present invention, a manual gate and a pneumatic gate are provided at the discharge port at the bottom of the powder silo, and the discharge port of the powder silo is sequentially connected to a frequency conversion airlock feeder, a weighing belt conveyor and an ejector.

[0007] In some embodiments of the present invention, the gas inlet of the injector is connected to a powder feeding fan. In some embodiments of the present invention, when multiple pulverized coal burners on the boiler are arranged in a tangential arrangement, multiple uni-burners are also arranged in a tangential arrangement. The uni-burners are installed at the secondary air inlet position between the bottom two layers of pulverized coal burners, or at the bottom air inlet position on the lower side of the furnace. In some embodiments of the present invention, when multiple pulverized coal burners on a boiler are arranged in a front-to-back wall opposing manner, the single burner is installed on the side wall of the boiler. In some embodiments of the present invention, the element burner is provided with a single layer or multiple layers.

[0008] In some embodiments of the present invention, the direct-fired pulverizing system includes a pulverized coal mill, a pulverized coal blower, and a pulverized coal distributor connected in sequence, wherein the pulverized coal distributor is connected to a pulverized coal burner via a pipeline.

[0009] In some embodiments of the present invention, a bag filter or cyclone dust collector is provided on the top of the powder silo, and a nitrogen protection system is provided on the powder silo.

[0010] In some embodiments of the present invention, the powder silo stores coal powder, biomass fuel powder, or organic solid waste pyrolysis carbon powder.

[0011] In a second aspect of the invention, a method for operating a boiler pulverizing system suitable for multiple fuels and flexible operation is provided, comprising: When the boiler is running at low load, biomass fuel powder or coal powder is supplied to the primary burner through an intermediate storage pulverizing system. After the biomass fuel powder or coal powder is burned in the primary burner, the reducing high-temperature flue gas is sent into the furnace of the boiler for continued combustion. The direct-fired pulverizing system does not supply pulverized coal. During normal operation, pulverized coal is supplied to the pulverized coal burner through a direct-fired pulverizing system. The pulverized coal burner mixes the air with the pulverized coal and then sends it into the boiler furnace, where it is ignited and burned by the flames inside the furnace. The intermediate storage pulverizing system does not supply pulverized coal. When the boiler needs to rapidly increase its load, the intermediate storage pulverizing system supplies pulverized coal. When the boiler is running at full load, biomass fuel powder or pulverized coal is supplied to the primary burner through an intermediate storage pulverizing system. After the biomass fuel powder or pulverized coal is burned in the primary burner, the reducing high-temperature flue gas is sent into the furnace of the boiler for continued combustion. At the same time, pulverized coal is supplied to the pulverized coal burner through a direct-fired pulverizing system. The pulverized coal burner mixes the air and pulverized coal and sends it into the furnace of the boiler, where it is ignited and burned by the flame in the furnace.

[0012] One or more technical solutions of the present invention have the following beneficial effects: (1) This invention couples a direct-fired pulverizing system with an intermediate storage pulverizing system. Under normal load conditions, the direct-fired pulverizing system is put into operation; under special conditions such as low load, full load operation, and rapid load increase, the intermediate storage pulverizing system is put into operation. Therefore, the capacity of the intermediate storage system can be much smaller than that of an independent intermediate storage pulverizing system, which can effectively reduce investment and operating costs. In addition, the system can switch between storage and direct-fired systems, and the operation mode is flexible, which can meet the requirements of full-load operation and rapid peak shaving of the unit.

[0013] (2) The present invention uses an intermediate storage pulverizing system as a supply system for low-carbon fuels such as biomass. The pulverizing silo can store biomass fuel and ensure a stable supply of biomass fuel. The direct-fired system is used as a supply system for conventional pulverized coal. The two pulverizing systems are coupled to achieve mixed combustion of low-carbon fuels such as biomass and multiple fuels such as pulverized coal.

[0014] (3) The intermediate storage pulverizing system of the present invention is combined with the primary burner to deliver pulverized coal. The fuel is pre-ignited and burned in the primary burner, producing high-temperature reducing flue gas and pulverized coal, which increases the fuel temperature entering the boiler and ensures efficient and stable combustion of fuel in the furnace. It realizes the separation of fuel ignition and boiler combustion, and is not affected by combustion in the furnace and load. It can achieve stable ignition and combustion under any load, and eliminates the risk of fire extinguishing caused by the imbalance of air and coal concentration in the direct-fired system at low load.

[0015] (4) The present invention can be obtained by directly modifying the existing boiler pulverizing system. Whether it is a DC burner boiler with a four-corner tangent arrangement or a swirl burner boiler with a front and rear wall opposing arrangement, stable ignition and combustion under any load can be achieved by building a new pulverizing silo, an intermediate storage silo type pulverizing system and an original burner. Attached Figure Description

[0016] Figure 1 The pulverized coal feeding system for boilers where the pulverized coal burners are arranged in a tangential pattern at the four corners; Figure 2 The pulverized coal feeding system for boilers where the pulverized coal burners are arranged in an opposing configuration.

[0017] In the diagram: 1. Powder silo; 2. Feeding device; 3. Powder feeding fan; 4. Distributor; 5. Coal burner; 6. Boiler; 7. Grinding mill; 8. Powdered coal burner. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Example 1 In a typical embodiment of the present invention, a boiler pulverized coal feeding system applicable to multiple fuels and flexible operation is proposed, including a boiler 6, on which multiple primary burners 5 and multiple pulverized coal burners 8 are installed; the primary burners 5 are supplied with pulverized coal through an intermediate storage pulverizing system, and the primary burners 5 ignite the pulverized coal before sending it into the boiler 6; the pulverized coal burners 8 are supplied with pulverized coal through a direct-fired pulverizing system, and the pulverized coal burners 8 send the pulverized coal into the boiler 6, where it is ignited by a flame inside the boiler 6; the intermediate storage pulverizing system includes a grinding mill 7, a pulverized coal silo 1, a pulverized coal feeding fan 3, and a distributor 4 connected in sequence, and the distributor 4 is connected to the primary burners 5 through pipelines.

[0020] It is understandable that the pulverized coal feeding system of the aforementioned boiler 6 supplies pulverized coal through two systems: an intermediate storage pulverized coal system and a direct-fired pulverized coal system. The direct-fired pulverized coal system supplies pulverized coal and works with the pulverized coal burner 8 to achieve combustion of pulverized coal within the boiler 6. The intermediate storage pulverized coal system can supply both pulverized coal and biomass fuel powder when multiple fuels are being burned, making the system suitable for various fuel supplies. At the same time, the fuel supplied by the intermediate storage pulverized coal system is burned through the primary burner 5, meaning the fuel is ignited and burned inside the burner, emitting a high-temperature semi-gasification reducing flame, which is decoupled from combustion in the furnace and is not affected by combustion or load in the furnace. The primary burner 5 ignites the pulverized coal before sending it into the boiler 6, which can eliminate the risk of flameout caused by air-coal concentration imbalance in the direct-fired system at low loads. Meanwhile, the traditional pulverized coal burner 8 maintains direct-fired pulverized coal supply, ensuring combustion efficiency under normal loads and achieving the dual goals of flexible peak shaving and basic energy supply. In addition, the dual pulverizing systems serve as backups for each other. When the direct-fired coal mill fails, the primary burner 5 can independently maintain the boiler 6 at a low load, reducing losses from unplanned downtime.

[0021] In this embodiment, a manual and a pneumatic gate are installed at the discharge port at the bottom of the powder silo 1. The discharge port of the powder silo 1 is sequentially connected to a frequency converter airlock feeder, a weighing belt conveyor, and an ejector. Furthermore, the gas inlet of the ejector is connected to the powder feeding fan 3.

[0022] Understandably, the pulverizer 1 primarily serves to store fuel pulverizer, which can be either coal pulverizer or biomass fuel pulverizer. The source of biomass fuel is unrestricted; the power plant can achieve internal supply through external procurement or by building its own production equipment. The operation of the intermediate storage-type pulverizing system can be controlled by adjusting the opening and closing of the manual and pneumatic gates, thus enabling the system to switch between storage-type and direct-fired pulverizing. The variable frequency airlock feeder, weighing belt conveyor, and injector serve as the feeding device 2. The variable frequency airlock feeder dynamically adjusts the feeding rate according to the boiler 6 load, and works in real-time with the weighing belt conveyor to ensure a relatively stable flow rate to the injector. Air supplied by the pulverizer fan 3 is blown into the injector's gas inlet, creating a negative pressure on the feed side of the injector. This causes the gas to carry a large amount of biomass fuel pulverizer, and after thorough mixing, the mixture is divided into multiple paths by the coal pulverizer and sent to the corresponding primary burners 5 for pre-combustion. The inlet air source for the pulverizer fan 3 can be from the atmosphere or connected to the existing primary air system.

[0023] like Figure 1 As shown, when multiple pulverized coal burners 8 on boiler 6 are arranged in a tangential arrangement, multiple unidirectional burners 5 are also arranged in a tangential arrangement. The unidirectional burners 5 are installed at the secondary air inlet position between the bottom two layers of pulverized coal burners 8, or at the bottom air inlet position on the lower side of the furnace. Figure 1 In the described system, the pulverized coal burner 8 and the non-pulverized coal burner 5 are located at different heights in the furnace. Figure 1 This represents the height plane where the primary burner 5 is located, therefore the pulverized coal burner 8 is not shown in the figure.

[0024] It can be understood that the primary burner 5 is placed between the two lowest layers of burners or at the bottom air position, using a high-temperature pre-combustion flame to heat the cold ash hopper area of ​​the furnace from the bottom, thereby increasing the overall temperature level of the furnace under low load and preventing a decrease in the pulverized coal combustion rate.

[0025] like Figure 2 As shown, when multiple pulverized coal burners 8 on boiler 6 are arranged in a front-to-back wall configuration, the single burner 5 is installed on the side wall of boiler 6.

[0026] It can be understood that the burner 5 is installed on the side wall, and the pre-combustion flame penetrates the low-temperature zone in the center of the furnace laterally, breaking the local high-temperature oxygen-rich zone formed by the swirl burner at low load, promoting uniform combustion of fuel, and reducing NOx generation.

[0027] Currently, the mainstream burner arrangements are the four-corner tangential once-through burner arrangement and the front and rear wall opposed swirl burner arrangement. This embodiment proposes a multi-fuel pulverized coal feeding system for boiler 6, suitable for various unit arrangements. Therefore, the system provided in this embodiment can be used directly as a new system, or it can be flexibly modified from an existing boiler 6 system to obtain the system of this embodiment. This system has wide applicability.

[0028] It should be noted that the primary burner 5 in this embodiment can be set in multiple layers as needed, and the powder bins 1 can also be set in multiple layers as needed. For example, each layer of primary burner 5 can correspond to one powder bin 1, or multiple layers of primary burners 5 can correspond to one powder bin 1. Here, regardless of whether it is a four-corner tangential DC burner arrangement or a counter-flow swirl burner arrangement, the number of powder bins 1 and the number of layers of primary burners 5 are not limited.

[0029] In this embodiment, the direct-fired pulverizing system includes a coal pulverizer 7, a coal pulverizer fan, and a coal pulverizer connected in sequence, with the coal pulverizer connected to a pipeline coal pulverizer burner 8.

[0030] Understandably, the direct-fired pulverizing system is not shown in the figure. The difference between the direct-fired pulverizing system and the intermediate storage pulverizing system is that the direct-fired pulverizing system does not have a pulverizing silo 1. After grinding, the pulverized coal is directly blown into the furnace for combustion by primary air, which is the existing structure. The direct-fired pulverizing system is a commonly used pulverizing system in existing power plants. The direct-fired pulverizing system in this invention is no different from the conventional direct-fired pulverizing system, so it is not shown in the figure.

[0031] It should be noted that both the primary burner 5 and the pulverized coal burner 8 used in this embodiment adopt existing structures. The difference between the two is that the primary burner 5 ignites and burns internally before being discharged, hence the term "primary combustion." The pulverized coal burner 8 is actually an air-coal mixture injector, relying on the flame inside the furnace to supply ignition heat, working together to achieve ignition and combustion. By using the primary burner 5, true internal ignition and combustion are achieved. The primary burner 5 ignites the pulverized coal before sending it into the boiler 6, and then discharges high-temperature reducing flue gas, decoupling it from the combustion inside the furnace and thus being unaffected by the combustion inside the furnace or the load. For a tangential arrangement, the pulverized coal burner 8 can be a direct-flow burner; for a counter-flow arrangement, it can be a swirl burner.

[0032] In this embodiment, a bag filter or cyclone dust collector is installed on the top of the powder silo 1, and a nitrogen protection system is installed on the powder silo 1.

[0033] Considering the safety concerns associated with setting up powder silo 1, a bag filter or cyclone dust collector is installed at the top of powder silo 1 to separate combustible gases. Simultaneously, a nitrogen protection system provides explosion protection. When CO and O2 levels reach warning values, the nitrogen protection system promptly fills powder silo 1 with high-purity nitrogen to ensure its safe operation and mitigate the storage risks associated with the high volatility of biomass powder, high-volatile bituminous coal, or lignite. The exhaust steam separated by the bag filter or cyclone dust collector can be fed into boiler 6 for further combustion; if the separated air meets quality standards, it can also be discharged externally.

[0034] The pulverized coal feeding system for boilers with multiple combustion fuels provided in this embodiment has the following operating modes: When boiler 6 is running at low load, biomass fuel powder or coal powder is supplied to the primary burner 5 through the intermediate storage pulverizing system. After the biomass fuel powder or coal powder is burned in the primary burner 5, the flame is sent into the furnace of boiler 6 to continue burning. The direct-fired pulverizing system does not supply pulverized coal. During normal operation of boiler 6, pulverized coal is supplied to pulverized coal burner 8 through direct-fired pulverizing system. Pulverized coal burner 8 mixes air with pulverized coal and sends it into the furnace of boiler 6, where it is ignited and burned by the flame in the furnace. The intermediate storage pulverizing system does not supply pulverized coal. When boiler 6 needs to rapidly increase load, the intermediate storage pulverizing system supplies pulverized coal. When the boiler 6 is running at full load, biomass fuel powder or pulverized coal is supplied to the primary burner 5 through an intermediate storage pulverizing system. After the biomass fuel powder or pulverized coal is burned in the primary burner 5, the flame is sent into the furnace of the boiler 6 to continue burning. At the same time, pulverized coal is supplied to the pulverized coal burner 8 through a direct-fired pulverizing system. The pulverized coal burner 8 mixes the air and pulverized coal and sends it into the furnace of the boiler 6, where it is ignited and burned by the flame in the furnace.

[0035] This system can switch between silo-type and direct-fired pulverizing, offering flexible operation and meeting the needs of full-load operation and rapid peak shaving. When the unit needs to rapidly increase load, pulverized coal or biomass fuel from the external pulverizer silo 1 is directly added to the primary air duct of the direct-fired pulverizing system, increasing the pulverized coal concentration in the primary air, shortening the unit's start-up and load-increasing time, and enhancing high-load capacity. Simultaneously, the external pulverizer silo 1 supplies pulverized coal independently. After pre-combustion by the primary burner 5 to generate a high-temperature reducing flame, the pulverized coal is introduced into the boiler, achieving stable ignition and combustion under any load. The silo 1 can also store easily combustible, high-quality coal. When the unit needs low-load peak shaving, the high-quality coal from the external silo 1 is added, effectively improving the unit's low-load stable combustion capability. Furthermore, the independent pulverizer silo 1 eliminates the impact of low pulverized coal concentration and poor combustion stability at low loads in the direct-fired pulverizing system. Combined with the pre-combustion of pulverized coal by the primary burner 5, stable ignition and combustion under any load can be achieved.

[0036] Example 2 In a typical embodiment of the present invention, a method for pulverizing coal in a boiler applicable to multiple fuels is provided, comprising: When the boiler is running at low load, biomass fuel powder or coal powder is supplied to the primary burner through an intermediate storage pulverizing system. After the biomass fuel powder or coal powder is burned in the primary burner, the flame is sent into the furnace of the boiler to continue burning. The direct-fired pulverizing system does not supply pulverized coal. During normal operation, pulverized coal is supplied to the pulverized coal burner through a direct-fired pulverizing system. The pulverized coal burner mixes the air with the pulverized coal and then sends it into the boiler furnace, where it is ignited and burned by the flames inside the furnace. The intermediate storage pulverizing system does not supply pulverized coal. When the boiler needs to rapidly increase its load, the intermediate storage pulverizing system starts supplying pulverized coal. When the boiler is running at full load, pulverized biomass fuel or pulverized coal is supplied to the primary burner through an intermediate storage pulverizing system. After the pulverized biomass fuel or pulverized coal is burned in the primary burner, the flame is sent into the furnace of the boiler to continue burning. At the same time, pulverized coal is supplied to the pulverized coal burner through a direct-fired pulverizing system. The pulverized coal burner mixes the air and pulverized coal and sends it into the furnace of the boiler, where it is ignited and burned by the flame in the furnace.

[0037] When the boiler load is below 40%, the furnace temperature drops sharply, and the direct-fired system is prone to flameout due to the imbalance of air and pulverized coal concentration. At this time, the intermediate storage system completely solves this problem through the pre-combustion mechanism of the burner (fuel is ignited inside the burner and then sent into the furnace). The flame (high-temperature reducing gas) discharged from the burner has a temperature >900℃, which directly heats the cold ash hopper area of ​​the furnace and maintains the basic combustion temperature.

[0038] When the boiler is running at full load, the direct-fired system undertakes 70% to 80% of the base load to ensure efficient combustion of pulverized coal, while the intermediate storage system provides an additional 20% to 30% load capacity. The pre-combustion flame increases the overall temperature of the furnace and reduces coal consumption for power supply.

[0039] Under normal operating conditions, the intermediate storage system is shut down to avoid energy consumption (such as power consumption by the pulverized coal fan and nitrogen protection); the direct-fired system maintains a stable pulverized coal concentration and achieves the design peak combustion efficiency within the 70%~100% load range.

[0040] When a rapid load increase is required, the load increase rate of the direct-fired system is limited, while the storage system achieves "fuel injection in seconds" through the pre-stored powder silo, the powder delivery fan starts immediately, and the variable frequency airlock feeder adjusts the flow rate as needed; the pre-combustion flame of the burner is established in a short time, which increases the load increase rate.

[0041] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A boiler pulverizing system suitable for multiple fuels and flexible operation, characterized in that, The system includes a boiler equipped with multiple pulverized coal burners and multiple pulverized coal burners. The pulverized coal burners are supplied with pulverized coal through an intermediate storage pulverizing system, whereby the pulverized coal is ignited before being fed into the boiler. The pulverized coal burners are supplied with pulverized coal through a direct-fired pulverizing system, whereby the pulverized coal is fed into the boiler and ignited by a flame inside the boiler. The intermediate storage pulverizing system includes a grinding mill, a pulverized coal silo, a pulverized coal blowing fan, and a distributor connected in sequence, with the distributor connected to the pulverized coal burners via pipelines.

2. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 1, characterized in that, The powder silo is equipped with a manual and a pneumatic gate at the discharge port at the bottom. The discharge port of the powder silo is connected in sequence to a frequency conversion airlock feeder, a weighing belt conveyor and an ejector.

3. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 2, characterized in that, The gas inlet of the ejector is connected to the powder feeding fan.

4. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 1, characterized in that, When multiple pulverized coal burners on a boiler are arranged in a tangential configuration, multiple inter-burners are also arranged in a tangential configuration. The inter-burners are installed at the secondary air inlet between the bottom two layers of pulverized coal burners, or at the bottom air inlet on the lower side of the furnace.

5. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 1, characterized in that, When multiple pulverized coal burners on a boiler are arranged in a front-to-back wall configuration, the burner is installed on the side wall of the boiler.

6. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 4 or 5, characterized in that, The burner may be configured with a single layer or multiple layers.

7. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 1, characterized in that, The direct-fired pulverizing system includes a pulverized coal mill, a pulverized coal fan, and a pulverized coal distributor connected in sequence. The pulverized coal distributor is connected to the pulverized coal burner via a pipeline.

8. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 1, characterized in that, A bag filter or cyclone dust collector is installed on the top of the powder silo, and a nitrogen protection system is installed on the powder silo.

9. The boiler pulverizing system applicable to multiple fuels and flexible operation as described in claim 1, characterized in that, The powder silo stores pulverized coal, biomass fuel powder, or pyrolysis char powder from organic solid waste.

10. A method of operating a boiler pulverized coal feeding system applicable to multiple fuels and flexible operation as described in any one of claims 1-9, characterized in that, include: When the boiler is running at low load, biomass fuel powder or coal powder is supplied to the primary burner through an intermediate storage pulverizing system. After the biomass fuel powder or coal powder is burned in the primary burner, the reducing high-temperature flue gas is sent into the furnace of the boiler for continued combustion. The direct-fired pulverizing system does not supply pulverized coal. During normal operation, pulverized coal is supplied to the pulverized coal burner through a direct-fired pulverizing system. The pulverized coal burner mixes the air with the pulverized coal and then sends it into the boiler furnace, where it is ignited and burned by the flames inside the furnace. The intermediate storage pulverizing system does not supply pulverized coal. When the boiler needs to rapidly increase its load, the intermediate storage pulverizing system supplies pulverized coal. When the boiler is running at full load, biomass fuel powder or pulverized coal is supplied to the primary burner through an intermediate storage pulverizing system. After the biomass fuel powder or pulverized coal is burned in the primary burner, the reducing high-temperature flue gas is sent into the furnace of the boiler for continued combustion. At the same time, pulverized coal is supplied to the pulverized coal burner through a direct-fired pulverizing system. The pulverized coal burner mixes the air and pulverized coal and sends it into the furnace of the boiler, where it is ignited and burned by the flame in the furnace.

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