阅读说明：本技术 一种用于电厂煤粉锅炉超低负荷稳燃的方法和装置 (Method and device for ultra-low load stable combustion of pulverized coal fired boiler in power plant ) 是由 赵建涛 房倚天 李德宝 李春玉 聂伟 黄戒介 贾丽涛 于 2021-09-10 设计创作，主要内容包括：本发明公开了一种用于电厂煤粉锅炉超低负荷稳燃的方法和装置,属于燃煤锅炉发电领域,目的在于实现煤粉锅炉在超低负荷下稳定运行,满足电网灵活性调峰的要求。原煤首先由磨煤机制成粒径小于200μm的煤粉；其中1%-5%的煤粉由气流携带进入稳燃器；通过调整气量控制稳燃器温度800-1100℃,煤粉发生贫氧燃烧和气化反应,生成高温燃气；高温燃气夹带未燃尽的煤粉通过引火管喷入锅炉中,起到稳定锅炉内煤粉燃烧的作用。本发明涉及的稳燃器由喷嘴、电加热器、引火管、隔热耐火衬里、外壳组成。本发明具有系统简单、操作灵活、煤种适应性好、响应速度快、运行成本低、投资少的优点。(The invention discloses a method and a device for ultra-low load stable combustion of a pulverized coal boiler in a power plant, belongs to the field of coal-fired boiler power generation, and aims to realize stable operation of the pulverized coal boiler under ultra-low load and meet the requirement of power grid flexibility peak regulation. Firstly, making raw coal into coal powder with the particle size of less than 200 mu m by a coal mill; wherein 1-5% of the coal powder is carried by the airflow and enters the combustion stabilizer; controlling the temperature of a flame stabilizer to be 800-1100 ℃ by adjusting the gas flow, and generating high-temperature fuel gas by generating oxygen-deficient combustion and gasification reaction on the pulverized coal; the high-temperature fuel gas with the unburned coal powder is sprayed into the boiler through the ignition tube, so that the effect of stabilizing the combustion of the coal powder in the boiler is achieved. The invention relates to a flame stabilizer which comprises a nozzle, an electric heater, an ignition tube, a heat-insulating refractory lining and a shell. The invention has the advantages of simple system, flexible operation, good coal adaptability, high response speed, low operation cost and less investment.)

1. A method for ultra-low load stable combustion of a pulverized coal fired boiler in a power plant is characterized by comprising the following steps:

(1) raw coal is fed into a coal mill, the operating conditions of the coal mill are controlled, raw coal particles are ground into coal powder with the particle size smaller than 200 mu m, air carrying the coal powder flows out of the top of the coal mill and serves as primary air of a coal powder boiler, and the air is fed into the boiler;

(2) a part of primary air carrying coal dust is controlled by a draught fan to enter a cyclone separator and a bag-type dust collector through a branch pipeline beside an air outlet of the coal mill, and the collected coal dust enters an intermediate bin;

(3) the coal powder in the intermediate bin enters an air conveyer under the control of a feeder, and the ratio of air to the coal powder is controlled to be 0.2-5Nm³The pulverized coal enters the stable burner from the central channel of the burner under the condition of pneumatic conveying, and the outlet air flow rate of the burner is 20-60 m/s;

(4) introducing 150-350 ℃ preheated air from the outer ring channel of the burner, and controlling the flow rate of gas at the outlet of the burner to be 10-20 m/s;

(5) the coal powder and air are subjected to oxygen-deficient combustion and gasification in the flame stabilizer to generate high-temperature fuel gas mainly containing CO, and the coal quantity and the gas quantity are adjusted to maintain the temperature of 800-;

(6) the high-temperature fuel gas carries unburned coal powder and is sprayed into the boiler through the ignition tube of the flame stabilizer, and the coal powder carried by primary air is ignited, so that the effect of stabilizing the combustion of the coal powder in the hearth of the boiler is achieved.

2. The method for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant as claimed in claim 1, characterized in that: the raw coal in the step (1) is lignite, bituminous coal or anthracite.

3. The method for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant as claimed in claim 1, characterized in that: the step (A) of5) The ratio of the total air amount in the flame stabilizer to the pulverized coal amount is 0.5-5 Nm³Per kg of coal fines.

4. The method for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant as claimed in claim 1, characterized in that: and (5) the flow speed of the gas in the flame stabilizer in the step (5) is 0.5-5 m/s.

5. The method for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant as claimed in claim 1, characterized in that: and (3) the residence time of the gas and the solid particles in the flame stabilizer in the step (5) is 0.5-10 s.

6. The method for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant as claimed in claim 1, characterized in that: and (5) preheating the combustion stabilizer to 600-900 ℃ by adopting an electric heating mode before introducing the pulverized coal.

7. A device for ultra-low load stable combustion of a pulverized coal fired boiler in a power plant is used for implementing the method for ultra-low load stable combustion of the pulverized coal fired boiler in the power plant according to any one of the claims 1 to 6, and is characterized in that: the device comprises a coal mill, a cyclone separator and a bag-type dust collector which are connected in sequence, wherein a gas outlet of the bag-type dust collector is connected with an induced draft fan; the coal dust outlets at the lower parts of the cyclone separator and the bag-type dust collector are connected with an intermediate bin; the lower part of the intermediate bin is connected with a pulverized coal conveyor through a pulverized coal feeder; the horizontal direction of the pulverized coal conveyor is provided with an air inlet and an air outlet, the air outlet of the pulverized coal conveyor is connected with a burner of a flame stabilizer, the burner is of an annular sleeve type structure and consists of a central pulverized coal channel and an outer ring combustion air channel; the outlet of the flame stabilizer is connected with an ignition tube, the ignition tube extends into a boiler hearth from a primary air port of the boiler, the ignition tube is an inner tube, a primary air inlet tube is an outer tube, and the ignition tube and the primary air inlet tube form a sleeve;

the stable burner consists of a pulverized coal burner, a shell and an ignition tube, wherein a double-channel burner is arranged at the inlet of the furnace body, the shell, a heat insulating material and a refractory material are sequentially arranged in the furnace body from outside to inside, and an electric heating element is arranged in the refractory material.

8. The device for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant according to claim 7, characterized in that: the burner of the flame stabilizer is a double-channel burner and consists of a central channel and an outer ring channel.

9. The device for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant according to claim 7, characterized in that: the allowable service temperature of the refractory material of the flame stabilizer is more than 1200 ℃, and the compressive strength is more than or equal to 60 MPa.

10. The device for ultra-low load stable combustion of the pulverized coal fired boiler of the power plant according to claim 7, characterized in that: the heat conductivity coefficient of the heat insulation material of the flame stabilizer is less than or equal to 0.5W/m.k.

Technical Field

The invention relates to a method and a device for ultra-low load stable combustion of a pulverized coal boiler in a power plant, belonging to the field of power generation of coal-fired boilers.

Background

The peak-to-valley ratio of generated energy is huge due to the characteristics of intermittency, fluctuation and randomness of wind power generation and solar power generation due to changes of weather, seasons and day and night. In order to solve the dilemma of new energy consumption and carry out thermal power flexibility transformation, the necessary requirement of stable power supply is to adopt a coal-fired thermal power generating unit to carry out peak shaving.

When the pulverized coal boiler of the power plant operates at a deep peak regulation low load, the calorific value of the coal is greatly reduced, the temperature of a hearth is reduced, the combustion stability of the pulverized coal is reduced, the boiler is easy to extinguish a fire, and the technical difficulty of maintaining stable combustion of the boiler is very high. The low-load stable combustion technology of the existing coal-fired boiler mainly comprises an auxiliary fuel stable combustion technology, a plasma stable combustion technology, an oxygen-enriched stable combustion technology, an air preheating stable combustion technology and the like. Chinese patents 201410467276.0, 201010244692.6 disclose a fuel and gas ignition stable combustion system respectively, but because of the high price of oil and gas, the mode tends to be replaced by oil-free stable combustion technology in the future. Chinese patents 201710109787.9, 201721294248.9, 201810192558.2, 201810867626.0, 201820453959.4 and 201710931919.6 propose improved burners, air intake mode, coal feeding mode, coal dust concentration separation mode and the like, which can improve the combustion effect of the boiler to a certain extent, but cannot completely meet the requirement of ultra-low load stable combustion of the boiler. Chinese patents 201920041637.3 and 201810595813.8 propose plasma ignition and combustion stabilizing systems with different structures and working modes, respectively, which utilize high voltage to generate electric arc, ionize air to generate plasma with extremely high energy density, and ignite pulverized coal airflow to achieve the purpose of combustion stabilizing. However, the plasma generator has high manufacturing cost, complex system and short service life. Chinese patents 201210083504.5, 201710661801.6, 201710483595.4, 201910584293.5, 201920008532.8 and 201920454263.8 respectively adopt different modes and equipment to preheat coal powder and primary air, improve the outlet temperature of a coal mill, improve the fineness of the coal powder and improve the combustion effect of the coal powder. The method can reduce the heat required by heating the pulverized coal airflow to the combustion temperature, and the pulverized coal airflow can reach the ignition temperature more easily under the condition of equivalent convection heat and radiation heat, so that the pulverized coal is easier to ignite and stably combust. The technology has the biggest difference in the selection of a preheating mode, and the difficulty is in the control of preheating temperature, and the temperature is too low to achieve the effect; and if the temperature is too high, detonation is easy to cause in the pipeline, and potential safety hazards of explosion exist.

Disclosure of Invention

The invention aims to provide an economical and efficient method and device for ultra-low load stable combustion of a pulverized coal boiler of a power plant, and solves the technical problem of low-load stable combustion during deep peak shaving of the pulverized coal boiler of a coal-fired power plant.

The invention discloses an ultra-low load stable combustion method of a pulverized coal boiler in a power plant, which aims at the defects of low heat and unstable flame in a hearth during ultra-low load operation of the boiler, and provides the method that a small part of pulverized coal is partially gasified in a stable combustion device to generate high-temperature fuel gas, the high-temperature fuel gas and the hot pulverized coal enter the hearth, pulverized coal airflow is ignited by virtue of high temperature, the heat of a flame area is supplemented, the stability of the flame is ensured, and the stable combustion of the pulverized coal in the hearth during the ultra-low load operation of the boiler is realized.

The invention provides a method for ultralow-load stable combustion of a pulverized coal fired boiler in a power plant, which comprises the following steps of:

(1) raw coal is fed into a coal mill, the operating conditions of the coal mill are controlled, raw coal particles are ground into coal powder with the particle size smaller than 200 mu m, air carrying the coal powder flows out of the top of the coal mill and serves as primary air of a coal powder boiler, and the air is fed into the boiler;

(2) a draught fan is adopted to control primary air carrying coal dust to enter a cyclone separator and a bag-type dust collector on a branch pipeline beside an air outlet of the coal mill, and the collected coal dust enters an intermediate bin;

(3) the coal powder in the intermediate bin enters an air conveyer under the control of a feeder, and the ratio of air to the coal powder is controlled to be 0.2-5Nm³The pulverized coal enters the stable burner from the central channel of the burner under the condition of pneumatic conveying, and the outlet air flow rate of the burner is 20-60 m/s;

(4) introducing 150-350 ℃ preheated air from the outer ring channel of the burner, and controlling the flow rate of gas at the outlet of the burner to be 10-20 m/s;

(5) the coal powder and air are subjected to oxygen-deficient combustion and gasification in the flame stabilizer to generate high-temperature fuel gas mainly containing CO, and the coal quantity and the gas quantity are adjusted to maintain the temperature of 800-;

(6) the high-temperature fuel gas carries unburned coal powder and is sprayed into the boiler through the ignition tube of the flame stabilizer, and the coal powder carried by primary air is ignited, so that the effect of stabilizing the combustion of the coal powder in the hearth of the boiler is achieved.

The raw coal of step (1) as described above may be lignite, bituminous coal or anthracite.

The ratio of the total air amount to the pulverized coal amount in the flame stabilizer in the step (5) is 0.5-3 Nm³Per kg of coal fines.

The flow speed of the gas in the flame stabilizer in the step (5) is 0.5-5 m/s.

The residence time of the gas and solid particles in the flame stabilizer of the step (5) is 0.5-10 s.

The combustion stabilizer in the step (5) is preheated to 600-900 ℃ by adopting an electric heating mode before the pulverized coal is introduced.

In order to realize the method for the ultra-low load stable combustion of the pulverized coal fired boiler in the power plant, a device for the ultra-low load stable combustion of the pulverized coal fired boiler in the power plant is designed: the device comprises a coal mill, a cyclone separator and a bag-type dust collector which are connected in sequence, wherein a gas outlet of the bag-type dust collector is connected with an induced draft fan; the coal dust outlets at the lower parts of the cyclone separator and the bag-type dust collector are connected with an intermediate bin; the lower part of the intermediate bin is connected with a pulverized coal conveyor through a pulverized coal feeder; the horizontal direction of the pulverized coal conveyor is provided with an air inlet and an air outlet, the air outlet of the pulverized coal conveyor is connected with a burner of a flame stabilizer, the burner is of an annular sleeve type structure and consists of a central pulverized coal channel and an outer ring combustion air channel; the outlet of the flame stabilizer is connected with an ignition tube, the ignition tube extends into a boiler hearth from a primary air port of the boiler, the ignition tube is an inner tube, a primary air inlet tube is an outer tube, and the ignition tube and the primary air inlet tube form a sleeve.

The stable burner consists of a pulverized coal burner, a shell and an ignition tube, wherein a double-channel burner is arranged at the inlet of the furnace body, the shell, a heat insulating material and a refractory material are sequentially arranged in the furnace body from outside to inside, and an electric heating element is arranged in the refractory material.

The burner of the flame stabilizer is a double-channel burner and consists of a central channel and an outer ring channel.

The allowable service temperature of the refractory material of the flame stabilizer is more than 1200 ℃, and the compressive strength is more than or equal to 60 MPa.

The heat conductivity coefficient of the heat insulating material of the flame stabilizer is less than or equal to 0.5W/m.k.

The invention provides a stable combustion mode based on coal oxygen-deficient combustion gasification on the basis of comprehensively considering the advantages and the disadvantages of the prior art, which is characterized in that coal powder is gasified in a stable combustion device in oxygen-deficient mode to generate high-temperature fuel gas, and the high-temperature fuel gas is introduced into a hearth, and primary air coal powder airflow is ignited by virtue of high temperature, and meanwhile, heat of a flame area is supplemented, so that the ultralow load stable combustion of a pulverized coal boiler is realized.

The invention has the beneficial effects that:

(1) the adaptability of the coal types is good, and the coal type combustion power generation boiler can be used for combustion power generation boilers of different coal types;

(2) the high-temperature fuel gas which is partially gasified by the pulverized coal is adopted for supporting combustion, the process is simple, and the operation cost is low; by adopting the technical scheme of the invention, the load of the pulverized coal boiler can be reduced to be below 20%, the burnout rate of the pulverized coal is high, and the requirement of ultralow load peak regulation is met;

(3) the combustion-supporting coal quantity can be flexibly adjusted, and the operation is flexible, simple and reliable; the response is quick, and the method can adapt to a quick peak regulation process;

(4) the occupied area is small, the investment is low, and the field reconstruction is convenient; compared with the prior art, the method has the advantages of economy, environmental protection, energy conservation, consumption reduction and the like;

(5) the invention is suitable for stable combustion of coal dust in the flexible peak regulation process of the pulverized coal boiler, and can also be used for the combustion process of coal, biomass and organic carbon-containing wastes.

Drawings

FIG. 1 is a schematic diagram of an apparatus for ultra-low load stable combustion of a pulverized coal fired boiler in a power plant according to the present invention;

fig. 2 is a schematic structural diagram of a flame stabilizer.

In the figure, 1 is a coal mill, 2 is a cyclone separator, 3 is a bag-type dust remover, 4 is an intermediate bin, 5 is a feeder, 6 is a gas conveyer, 7 is a burner, 8 is a flame stabilizer, 9 is a primary air inlet of a boiler, 10 is a firing pipe, 11 is a boiler, 12 is an induced draft fan, 13 is an electric heating element, 14 is a heat insulating material, 15 is a flame stabilizer shell, 16 is a refractory material, 17 is a burner central channel, and 18 is a burner outer ring channel.

Detailed Description

The invention will be described in further detail below with reference to the accompanying drawings: the present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation is given, but the scope of the present invention is not limited to the following embodiments.

As shown in fig. 1 and 2, the invention provides a device for ultra-low load stable combustion of a pulverized coal boiler in a power plant, which comprises a coal mill 1, a cyclone separator 2 and a bag-type dust collector 3 which are connected in sequence, wherein a gas outlet of the bag-type dust collector 3 is connected with a draught fan 12; the coal dust outlets at the lower parts of the cyclone separator 2 and the bag-type dust collector 3 are connected with an intermediate bin 4; the lower part of the intermediate bin 4 is connected with a gas conveyer 6 through a pulverized coal feeder 5; an air inlet and an air outlet are arranged in the horizontal direction of the gas conveyor, the air outlet of the gas conveyor is connected with a burner 7 of a flame stabilizer 8, and the burner 7 is of an annular sleeve type structure and consists of a central pulverized coal channel and an outer ring combustion air channel; the outlet of the flame stabilizer is connected with an ignition tube 10, the ignition tube extends into a boiler hearth from a primary air port of the boiler, the ignition tube is an inner tube, a primary air inlet tube is an outer tube, and the ignition tube and the primary air inlet tube form a sleeve.

The flame stabilizer 8 consists of a pulverized coal burner 7, a shell 15 and an ignition tube 10, the double-channel burner 7 is arranged at the inlet of the furnace body, the shell 15, a heat insulating material 14 and a refractory material 16 are sequentially arranged in the furnace body from outside to inside, and an electric heating element 13 is arranged in the wear-resistant castable.

The burner 7 of the flame stabilizer is a double-channel burner and consists of a burner central channel 17 and a burner outer ring channel 18.

The refractory material 16 of the flame stabilizer is corundum castable, the allowable use temperature is more than 1350 ℃, and the compressive strength is more than or equal to 60 MPa; the heat insulating material 14 of the flame stabilizer is made of light castable, and the heat conductivity coefficient is less than or equal to 0.35W/m.k.

The method for using the device for ultra-low load stable combustion of the pulverized coal fired boiler in the power plant is described by the specific embodiment.

Example 1:

the method for ultralow-load stable combustion of the pulverized coal fired boiler in the power plant comprises the following steps: high-activity Datong coal is used as a raw material; firstly, an electric heating element 13 is adopted to preheat a flame stabilizer to 800-850 ℃; raw coal is firstly sent into a coal mill 1, raw coal particles are ground into coal powder with the particle size smaller than 150 mu m, and air carrying the coal powder flows out of the top of the coal mill 1 to be used as primary air of a coal powder boiler; controlling the flow of a draught fan 12 at a bypass of primary air of the pulverized coal boiler, enabling the primary air carrying 1-1.5% of pulverized coal to enter a cyclone separator 2 and a bag-type dust collector 3, and enabling collected pulverized coal to enter an intermediate bin 4; the coal powder in the intermediate bin 4 enters an air conveyor 6 under the control of a feeder 5, and the ratio of air to the coal powder is controlled to be 0.5 Nm³The pulverized coal enters the combustion stabilizer 8 from the burner central channel 17 under the condition of pneumatic transmission, and the outlet air flow rate of the burner 7 is controlled to be 30 m/s; preheating air at 200 ℃ enters a flame stabilizer 8 from a burner outer ring channel 18, and the gas flow rate at the outlet of a nozzle outer ring is controlled to be 10 m/s; the coal powder and air are subjected to oxygen-deficient combustion and gasification in a flame stabilizer to generate high-temperature fuel gas mainly containing CO, and the temperature in the flame stabilizer 8 is 900-; the high-temperature fuel gas carries unburned coal dust and is sprayed into a boiler hearth 11 through a firing tube 10, and the coal dust carried by primary air is ignited, so that the effect of stabilizing the combustion of the coal dust in the boiler hearth is achieved.

Example 2:

the method for ultralow-load stable combustion of the pulverized coal fired boiler in the power plant comprises the following steps: with high activityThe Shenmu bituminous coal is used as a raw material; firstly, an electric heating element 13 is adopted to preheat a flame stabilizer to 750-800 ℃; raw coal is firstly sent into a coal mill 1, raw coal particles are ground into coal powder with the particle size smaller than 200 mu m, and air carrying the coal powder flows out of the top of the coal mill 1 to be used as primary air of a coal powder boiler; controlling the flow of a draught fan 12 at a bypass of primary air of the pulverized coal boiler, enabling the primary air carrying 1.5-2% of pulverized coal to enter a cyclone separator 2 and a bag-type dust collector 3, and enabling collected pulverized coal to enter an intermediate bin 4; the coal powder in the intermediate bin 4 enters an air conveyor 6 under the control of a feeder 5, and the ratio of air to the coal powder is controlled to be 1 Nm³The pulverized coal/kg is conveyed into the combustion stabilizer 8 through the central channel 17 of the burner 7 by air, and the air flow rate of the central outlet of the burner 7 is controlled to be 40 m/s; preheating air at 150 ℃ enters a flame stabilizer 8 from an outer ring channel 18 of a burner 7, and the gas flow rate at the outer ring outlet of the nozzle is controlled to be 15 m/s; the coal powder and air are subjected to oxygen-deficient combustion and gasification in a flame stabilizer to generate high-temperature fuel gas mainly containing CO, and the temperature in the flame stabilizer 8 is 950-; the high-temperature fuel gas carries unburned coal dust and is sprayed into a boiler hearth 11 through a firing tube 10, and the coal dust carried by primary air is ignited, so that the effect of stabilizing the combustion of the coal dust in the boiler hearth is achieved.

The device for realizing the ultralow-load stable combustion of the pulverized coal fired boiler in the power plant for realizing the method is as described in example 1.

Example 3

The method for ultralow-load stable combustion of the pulverized coal fired boiler in the power plant comprises the following steps: low-activity Yangquan anthracite is used as a raw material; firstly, an electric heating element 13 is adopted to preheat a flame stabilizer to 850-900 ℃; raw coal is firstly sent into a coal mill 1, raw coal particles are ground into coal powder with the particle size smaller than 100 mu m, and air carrying the coal powder flows out of the top of the coal mill 1 to be used as primary air of a coal powder boiler; controlling the flow of a draught fan 12 at a bypass of primary air of the pulverized coal boiler, enabling the primary air carrying 2.5-3% of pulverized coal to enter a cyclone separator 2 and a bag-type dust collector 3, and enabling collected pulverized coal to enter an intermediate bin 4; the coal powder in the intermediate bin 4 enters an air conveyor 6 under the control of a feeder 5, and the ratio of air to the coal powder is controlled to be 1 Nm³The pulverized coal/kg enters a flame stabilizer 8 from a central channel 17 of a burner 7 under the condition of pneumatic transmission and is controlledThe central outlet air flow rate of the burner 7 is 35 m/s; preheating air at 300-320 ℃ enters the flame stabilizer 8 from the outer ring channel 18 of the burner 7, and the gas flow rate at the outer ring outlet of the nozzle is controlled to be 12 m/s; the coal powder and air are subjected to oxygen-deficient combustion and gasification in the flame stabilizer to generate high-temperature fuel gas mainly comprising CO, and the temperature in the flame stabilizer 8 is 1000-; the high-temperature fuel gas carries unburned coal dust and is sprayed into a boiler hearth 11 through a firing tube 10, and the coal dust carried by primary air is ignited, so that the effect of stabilizing the combustion of the coal dust in the boiler hearth is achieved.

The device for realizing the ultralow-load stable combustion of the pulverized coal fired boiler in the power plant for realizing the method is as described in example 1.

Example 4

As shown in fig. 1 and fig. 2, the method and apparatus for ultra-low load stable combustion of a pulverized coal boiler in a power plant according to the present embodiment includes the following steps: taking low-activity lean coal of Huainan poverty as a raw material; firstly, an electric heating element 13 is adopted to preheat a flame stabilizer to 850-900 ℃; raw coal is firstly sent into a coal mill 1, raw coal particles are ground into coal powder with the particle size smaller than 100 mu m, and air carrying the coal powder flows out of the top of the coal mill 1 to be used as primary air of a coal powder boiler; controlling the flow of a draught fan 12 at a bypass of primary air of the pulverized coal boiler, enabling the primary air carrying 3-3.5% of pulverized coal to enter a cyclone separator 2 and a bag-type dust collector 3, and enabling collected pulverized coal to enter an intermediate bin 4; the coal powder in the intermediate bin 4 enters an air conveyor 6 under the control of a feeder 5, and the ratio of air to the coal powder is controlled to be 1.5 Nm³The pulverized coal/kg is conveyed into the combustion stabilizer 8 through the central channel 17 of the burner 7 by air, and the air flow rate of the central outlet of the burner 7 is controlled to be 30 m/s; preheating air at 300-320 ℃ enters the flame stabilizer 8 from the outer ring channel 18 of the burner 7, and the gas flow rate at the outer ring outlet of the nozzle is controlled to be 15 m/s; the coal powder and air are subjected to oxygen-deficient combustion and gasification in the flame stabilizer to generate high-temperature fuel gas mainly comprising CO, and the temperature in the flame stabilizer 8 is 1000-; the high-temperature fuel gas carries unburned coal dust and is sprayed into a boiler hearth 11 through a firing tube 10, and the coal dust carried by primary air is ignited, so that the effect of stabilizing the combustion of the coal dust in the boiler hearth is achieved.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.