High-temperature flue gas combustion-supporting pulverized coal boiler system of adiabatic furnace

Abstract

The invention discloses an adiabatic furnace high-temperature flue gas combustion-supporting pulverized coal boiler system, and relates to the technical field of solid waste fuel optimization utilization, the adiabatic furnace high-temperature flue gas combustion-supporting pulverized coal boiler system comprises an adiabatic furnace, the bottom surface of the adiabatic furnace is communicated with a primary air pipe, and the primary air pipe is provided with a primary fan; a gas-solid separation device is arranged at an outlet of the heat insulation furnace, a high-temperature flue is arranged at an outlet of the gas-solid separation device, high-temperature flue gas subjected to dust removal is fed into a gas mixing chamber through the high-temperature flue gas, the gas mixing chamber is arranged on a main secondary air pipe of the pulverized coal fired boiler, and the high-temperature flue gas mixed through the gas mixing chamber and secondary air form mixed secondary air. The mixed secondary air is fed into a hearth of the pulverized coal furnace through an original secondary air pipe of the pulverized coal furnace; the pebble coal is treated by the adiabatic furnace, so that the pebble coal is prevented from directly entering the coal mill to be mixed and ground with raw coal, the problem that internal parts of the coal mill are abraded due to high hardness and large abrasion index of the pebble coal is solved fundamentally, the equipment maintenance cost is reduced, and meanwhile, pebble coal solid waste treatment and utilization are realized.

Description

Technical Field

[0001] The present application relates to the technical field of optimized utilization of solid waste fuels, and in particular to an adiabatic furnace high-temperature flue gas-assisted coal powder boiler system. Background Art

[0002] Thermal power generation has long held a crucial position in the global energy mix. Pulverized coal boilers, as core equipment in thermal power generation, play a crucial role in efficient energy conversion and stable power supply. With the rapid development of industry and the growing demand for energy, improving the efficiency of pulverized coal boilers, reducing energy consumption, and minimizing pollutant emissions have become research priorities. Furthermore, the rational treatment and reuse of byproducts generated during power generation has become a crucial issue for achieving sustainable development.

[0003] In power plant pulverized coal boilers, the pulverized coal mill produces pebble coal as a byproduct. To recycle this resource, existing technologies utilize a pulverized coal furnace blending method to treat pebble coal. Specifically, pebble coal is mixed with pulverized coal at a specific ratio and then fed into the pulverized coal boiler for combustion. This method not only reduces the storage space and handling costs of pebble coal but also allows for secondary combustion of residual combustible materials in the pebble coal, significantly improving energy efficiency.

[0004] Regarding the above-mentioned related technologies, the inventors believe that due to the high hardness and large wear index of stone coal, it will cause wear to the internal components of the pulverizer during the process of mixing with coal powder, grinding and combustion. Frequent wear leads to a shortened replacement cycle of pulverizer components, increases the maintenance cost of the equipment, and affects the normal power generation of the power plant. Summary of the Invention

[0005] The purpose of this application is to provide an adiabatic furnace high-temperature flue gas-assisted coal-fired boiler system to improve the problem of wear on internal components of the pulverizer when using the coal-fired furnace blending method.

[0006] This application provides a pulverized coal boiler system for high-temperature flue gas combustion in an adiabatic furnace, which adopts the following technical solutions:

[0007] An adiabatic furnace high-temperature flue gas-assisted coal-fired boiler system comprises an adiabatic furnace mainly using pebble coal as fuel and a secondary fan. A primary air duct is provided on the bottom surface of the adiabatic furnace, and a primary fan for ventilating the inside of the adiabatic furnace is provided at one end of the primary air duct away from the adiabatic furnace; a gas-solid separation device is provided above the adiabatic furnace, and a flue is provided at the outlet of the gas-solid separation device. The high-temperature flue gas generated after the adiabatic furnace burns pebble coal is dust-removed by the gas-solid separation device and flows into the flue; the output end of the secondary fan is provided with the first and second air ducts, and the first and second air ducts are provided with a mixing chamber, and the end of the flue away from the gas-solid separation device is connected to the mixing chamber; the mixing chamber is connected with the second and third air ducts, and the second and third air ducts are provided with a pulverized coal boiler at one end away from the mixing chamber. The secondary fan ventilates the mixing chamber and mixes with the high-temperature flue gas, and then enters the pulverized coal boiler for combustion.

[0008] By adopting the above technical solution and using pebble coal as the main fuel for the adiabatic furnace, the pebble coal is avoided from directly entering the pulverizer for mixing with coal powder for grinding, which fundamentally solves the problem of pebble coal causing wear to the internal components of the pulverizer due to its high hardness and large wear index, thereby reducing the equipment maintenance cost; at the same time, the high-temperature flue gas generated by the adiabatic furnace is introduced into the mixing chamber after gas-solid separation, and is mixed with the air sent in by the secondary fan and used for combustion in the pulverized coal boiler, thereby realizing the effective utilization of the heat from the combustion of pebble coal and improving the overall energy utilization rate of the system. While solving the existing technical problems, it provides an additional combustion heat source for the pulverized coal boiler, thereby enhancing the energy conversion efficiency of the system.

[0009] Optionally, the adiabatic furnace is located above the primary air duct and is connected to an auxiliary air duct, and the auxiliary air duct is provided with an auxiliary fan for cooperating with the primary fan to adjust the amount of flue gas generated by the adiabatic furnace.

[0010] By adopting the above technical solution, the auxiliary fan can cooperate with the primary fan to accurately adjust the amount of air entering the adiabatic furnace according to the actual operating conditions, thereby controlling the amount of flue gas generated by the adiabatic furnace. This enables the system to better adapt to different operating conditions. Whether it is a change in fuel characteristics or fluctuations in external load demand, the combustion conditions of the adiabatic furnace can be stabilized by adjusting the air volume of the auxiliary fan and the primary fan, which helps to ensure that the amount and quality of high-temperature flue gas generated meet the combustion requirements of the pulverized coal boiler, thereby improving the stability and reliability of the system operation.

[0011] Optionally, when the pulverized coal boiler needs to intensify combustion at low load, the ventilation volume of the auxiliary fan is increased, the combustion of the adiabatic furnace is intensified, and the amount of high-temperature flue gas is increased.

[0012] By adopting the above technical solutions, routine shutdown reduces unnecessary energy consumption and improves the rationality and economy of energy utilization.

[0013] Optionally, the temperature of the high-temperature flue gas in the flue is in the range of 400°C to 900°C, the flue is connected to the adiabatic furnace and is provided with a circulation channel for circulating the low-temperature flue gas, and the flue is provided with a circulation valve.

[0014] By adopting the above technical solution, it is ensured that the high-temperature flue gas has appropriate heat and temperature, and can be effectively mixed with the secondary air to form a combustion-supporting gas that meets the combustion requirements of the pulverized coal boiler, thereby ensuring the combustion efficiency and stability of the pulverized coal boiler. By setting a low-temperature flue gas circulation duct and a circulation valve, part of the low-temperature flue gas can be returned to the adiabatic furnace to reduce damage or impact on subsequent equipment; the recycling of flue gas is realized, the thermal efficiency of the system is improved, and heat loss is reduced. At the same time, the flue gas circulation volume can be controlled by adjusting the circulation valve, further optimizing the combustion conditions of the adiabatic furnace and the overall performance of the system.

[0015] Optionally, a plurality of guide plates and a plurality of fixed spoiler fans are provided in the mixing chamber, the flue is provided on one side of the mixing chamber and upstream of the guide plate, and the spoiler fan is located downstream of the guide plate; the plurality of guide plates are arranged in sequence obliquely upward along the direction of the high-temperature flue gas in the flue, and the guide plates are arranged obliquely so that the high-temperature flue gas flows upward after being guided by the guide plates. The high-temperature flue gas is mixed with the wind in the first two air ducts arranged along the up and down directions and enters the latter two air ducts through the guide plates and spoiler fans.

[0016] By adopting the above technical solution, the design of the guide plate and spoiler fan in the mixing chamber enhances the mixing effect of the high-temperature flue gas and the secondary air of the pulverized coal boiler. The guide plate guides the high-temperature flue gas entering the mixing chamber obliquely upward to achieve preliminary mixing of the high-temperature flue gas and the secondary air; the spoiler fan promotes the rotation of the gas and air mixture, further increasing the contact area and mixing uniformity between the two, making the temperature and composition of the combustion-supporting gas entering the pulverized coal boiler more uniform, which is conducive to the full combustion of the pulverized coal and improves the combustion efficiency.

[0017] Optionally, a line connecting the bottom ends of the guide plates forms an angle of 4.5-5.5° with the horizontal line, and an angle between the guide plates and the direction of high-temperature flue gas in the flue is no more than 30°.

[0018] By adopting the above technical solution, it is ensured that the high-temperature flue gas can flow upward more smoothly after being guided by the guide plate and be fully mixed with the secondary air. At the same time, it avoids excessive flow resistance or insufficient mixing of the high-temperature flue gas due to improper angles, thereby further improving the mixing efficiency of the mixing chamber.

[0019] Optionally, the pulverized coal boiler includes a secondary air box, which is connected to the last two air ducts. The bottom of the secondary air box is provided with a plurality of ash hoppers for ash discharge, and the ash hoppers are provided with ash discharge valves. The secondary air box blows ash regularly.

[0020] By adopting the above technical solution, the secondary air box, as an important link in gas-solid separation, can reduce the flow rate of high-temperature flue gas carrying ash particles. Large-diameter ash particles settle into the ash hopper under the action of gravity and are regularly discharged through the ash discharge valve, reducing the wear of ash particles entering the pulverized coal boiler on the internal components of the boiler, extending the service life of the boiler, and also ensuring the cleanliness of the combustion-supporting gas entering the boiler, which is conducive to maintaining stable combustion and efficient operation of the boiler.

[0021] Optionally, the cross-section of the secondary air box is larger than the cross-sections of the latter two air ducts.

[0022] By adopting the above technical solution, the cross-sectional area change is used to make the high-temperature flue gas quickly decay in speed after entering the wind box, further enhancing the separation effect of ash particles, reducing the impact of ash particles on subsequent equipment, improving the combustion-supporting effect of high-temperature flue gas on pulverized coal boilers, and ensuring the stable operation of the system.

[0023] Optionally, the maximum heat output per unit time of the adiabatic furnace fuel is not greater than 10% of the maximum heat output per unit time of the pulverized coal boiler.

[0024] By adopting the above technical solution, the maximum heat output per unit time of the adiabatic furnace fuel is limited to no more than 10% of the maximum heat output per unit time of the pulverized coal boiler, ensuring that the high-temperature flue gas generated by the adiabatic furnace serves as an auxiliary heat source and does not cause excessive impact on the original combustion conditions of the pulverized coal boiler; it can fully utilize the heat generated by the combustion of pebble coal to improve energy utilization, and ensure the dominant position and stability of the combustion of the pulverized coal boiler, so that the system can maintain the balance and stable operation of the overall combustion system while utilizing pebble coal resources.

[0025] Optionally, after the pulverized coal boiler starts to burn stably, the adiabatic furnace begins to operate; before the pulverized coal boiler is shut down, the adiabatic furnace is shut down in advance; when the pulverized coal boiler is shut down due to an accident, the primary fan is turned off.

[0026] By adopting the above technical solution, the start-up and shutdown sequence and accident handling method of the adiabatic furnace and the pulverized coal boiler are clarified, and the safety and stability of the system operation are guaranteed. The adiabatic furnace is put into operation after the pulverized coal boiler starts and burns stably, avoiding the interference of the adiabatic furnace operation on the start-up process of the pulverized coal boiler; the pulverized coal boiler is shut down in advance before it is shut down to prevent the adiabatic furnace operation from affecting the shutdown operation of the pulverized coal boiler; the primary fan is turned off when the pulverized coal boiler is shut down due to an accident, and the adiabatic furnace fuel combustion is stopped in time, effectively protecting the system equipment.

[0027] In summary, this application includes at least one of the following beneficial technical effects of the adiabatic furnace high-temperature flue gas-assisted combustion pulverized coal boiler system:

[0028] 1. By using pebble coal as the main fuel for the adiabatic furnace, the pebble coal is prevented from being directly fed into the pulverizer for mixing with pulverized coal. This fundamentally solves the problem of pebble coal causing wear on internal components of the pulverizer due to its high hardness and large wear index, thereby reducing equipment maintenance costs. At the same time, the high-temperature flue gas generated by the adiabatic furnace is introduced into the mixing chamber after gas-solid separation. It is mixed with air supplied by the secondary fan and then used to support combustion in the pulverized coal boiler. This effectively utilizes the heat from the pebble coal combustion and improves the overall energy utilization rate of the system. While solving the problems of the existing technology, it also provides an additional combustion heat source for the pulverized coal boiler, enhancing the energy conversion efficiency of the system.

[0029] 2. The auxiliary fan can work with the primary fan to precisely adjust the amount of air entering the adiabatic furnace according to actual operating conditions, thereby controlling the amount of flue gas generated by the adiabatic furnace. This allows the system to better adapt to different operating conditions. Whether it is changes in fuel characteristics or fluctuations in external load demand, the air volume of the auxiliary fan and the primary fan can be adjusted to stabilize the combustion conditions of the adiabatic furnace. This helps to ensure that the amount and quality of high-temperature flue gas generated meet the combustion requirements of pulverized coal boilers, thereby improving the stability and reliability of system operation.

[0030] 3. Ensure that the high-temperature flue gas has appropriate heat and temperature, and can be effectively mixed with the secondary air to form a combustion-supporting gas that meets the combustion requirements of the pulverized coal boiler, thereby ensuring the combustion efficiency and stability of the pulverized coal boiler. By setting up a low-temperature flue gas circulation channel and a circulation valve, part of the low-temperature flue gas can be returned to the adiabatic furnace to reduce damage or impact on subsequent equipment; realize the recycling of flue gas, improve the thermal efficiency of the system, and reduce heat loss. At the same time, the flue gas circulation volume can be controlled by adjusting the circulation valve to further optimize the combustion conditions of the adiabatic furnace and the overall performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the adiabatic furnace high-temperature flue gas combustion pulverized coal boiler system;

[0032] Figure 2 is a cross-sectional schematic diagram for illustrating the structure of the gas mixing chamber in the embodiment;

[0033] Figure 3 It is a schematic diagram for illustrating the spoiler fan structure in the embodiment.

[0034] In the figure, 1. Adiabatic furnace; 11. Primary air duct; 12. Primary fan; 13. Auxiliary air duct; 14. Auxiliary fan; 2. Gas-solid separation device; 21. Flue; 211. Circulation duct; 212. Circulation valve; 3. Mixing chamber; 31. Guide plate; 32. Turbine fan; 4. First and second air ducts; 41. Secondary fan; 5. Second and second air ducts; 6. Pulverized coal boiler; 7. Secondary air box; 71. Ash hopper; 711. Ash discharge valve. DETAILED DESCRIPTION

[0035] The following is combined with Figure 1 -Attached Figure 3 , further details of this application are given.

[0036] A heat-insulating furnace high-temperature flue gas combustion pulverized coal boiler system, referring to Figure 1 , including an adiabatic furnace 1 mainly using pebble coal as fuel, and a secondary air blower 41; the adiabatic furnace 1 can use a fixed bed or a fluidized bed. The fixed bed adiabatic furnace 1 is usually made of high-temperature resistant refractory materials to form a furnace body, and a grate for carrying fuel is provided inside. The grate can be made of heat-resistant cast iron and is fixed to the bottom bracket of the furnace body by bolts; the fluidized bed adiabatic furnace 1 includes key components such as an air distribution plate. The air distribution plate is generally welded from steel plates, and ventilation holes are evenly provided on it to evenly distribute the gas and realize fluidized combustion of the fuel. Specifically, the fuel can be low-quality coal, coal gangue, pebble coal, and the diameter of the fuel particles is not greater than 10 mm.

[0037] Reference Figure 1 A primary air duct 11, made of high-temperature-resistant stainless steel, is welded to the bottom of the adiabatic furnace 1. A primary fan 12, which ventilates the furnace 1, is connected to the end of the primary air duct 11 away from the adiabatic furnace 1 via a flange. An auxiliary air duct 13, also made of high-temperature-resistant stainless steel, is welded to the adiabatic furnace 1 above the primary air duct 11. An auxiliary fan 14, used to coordinate with the primary fan 12 to adjust the amount of flue gas generated by the adiabatic furnace 1, is attached to the end of the primary air duct 11 away from the adiabatic furnace 1 via a flange.

[0038] Reference Figure 1 The auxiliary fan 14 increases or decreases the air volume according to the combustion state of the adiabatic furnace 1 to control the combustion intensity of the fuel in the adiabatic furnace 1. When the pulverized coal boiler 6 needs to intensify the combustion at low load, the ventilation volume of the auxiliary fan 14 is increased to intensify the combustion of the adiabatic furnace 1 and increase the amount of high-temperature flue gas. By controlling the amount of fuel placed and the air output size of the auxiliary fan 14, the maximum heat output per unit time of the adiabatic furnace 1 fuel is not greater than 10% of the maximum heat output per unit time of the pulverized coal boiler 6.

[0039] Reference Figure 1A gas-solid separation device 2 is provided above the adiabatic furnace 1 through a flange. The gas-solid separation device 2 can adopt a cyclone separator, which is mainly composed of a cylindrical shell, a conical bottom, an air inlet pipe, an exhaust pipe and an ash discharge pipe. The air inlet pipe is connected to the outlet of the adiabatic furnace 1 and fixed by welding. A flue 21 is provided at the outlet of the gas-solid separation device 2. In this embodiment, two groups of flues 21 are preferably provided. The flue 21 is made of high-temperature resistant alloy steel, and the flue 21 is connected and fixed to the gas-solid separation device 2 through a flange. The high-temperature flue gas generated by the combustion of stone coal in the adiabatic furnace 1 flows into the flue 21 after the ash particles are separated by the gas-solid separation device 2; the flue 21 is provided with a temperature control device (not shown in the figure), and the flue temperature range of the flue 21 from the outlet of the adiabatic furnace 1 is 400℃-900℃.

[0040] Reference Figure 1 The flue 21 is connected to the insulated furnace 1 and is provided with a circulation channel 211 for circulating low-temperature flue gas. The circulation channel 211 and the flue 21 are connected by welding. The flue 21 is provided with a circulation valve 212. The circulation valve 212 can be a high-temperature resistant butterfly valve, which is fixed to the flue 21 by bolts to control the circulation flow of the flue gas.

[0041] Reference Figure 1 The output end of the secondary fan 41 is provided with the first two air ducts 4, and the first two air ducts 4 are provided with a mixing chamber 3. The end of the flue 21 away from the gas-solid separation device 2 is connected to the mixing chamber 3. The first two air ducts 4 are made of galvanized steel plates, and the mixing chamber 3 is connected to the second two air ducts 5 by welding.

[0042] Reference Figure 2 、 Figure 3 , a number of guide plates 31 and a number of fixed spoiler fans 32 are provided in the mixing chamber 3. The spoiler fans 32 are in the form of static blades. The guide plates 31 are made of stainless steel plates and are fixed to the side walls of the mixing chamber 3 by means of rod supports and welding. The spoiler fans 32 are composed of a number of blades, preferably three in this embodiment. The blades are fixed to a fixed shaft by welding. The ends of the fixed shaft are fixed to the top of the mixing chamber 3 by bearing seats, so that the high-temperature flue gas and the wind introduced by the secondary fan 41 will generate a certain rotation through the spoiler fans 32, thereby enhancing their mixing. In this embodiment, there are preferably five guide plates 31 and two sets of spoiler fans 32. The specific number can be set according to the size of the mixing chamber 3. The flue 21 is provided on one side of the mixing chamber 3 and upstream of the guide plates 31. The spoiler fans 32 are located downstream of the guide plates 31.

[0043] Reference Figure 2 、 Figure 3, several guide plates 31 are arranged in sequence obliquely upward along the direction of the high-temperature flue gas in the flue 21, and the line connecting the bottom ends of the several guide plates 31 forms an angle of 4.5-5.5° with the horizontal line; the guide plates 31 are arranged obliquely so that the high-temperature flue gas can flow upward after being guided by the guide plates 31, and the angle between the guide plates 31 and the direction of the high-temperature flue gas in the flue 21 is not greater than 30°. The high-temperature flue gas mixes with the wind in the first two air ducts 4 arranged along the up and down directions and then enters the rear secondary air duct 5 through the guide plates 31 and the spoiler fans 32.

[0044] Reference Figure 1 The end of the secondary air duct 5 away from the mixing chamber 3 is provided with a pulverized coal boiler 6 through a flange. The pulverized coal boiler 6 can use a direct current burner or a swirl burner, corresponding to the four-corner tangential combustion method or the counter-combustion method. The direct current burner is generally composed of multiple nozzles, which are fixed to the burner body by welding; the swirl burner contains blades and other components to make the air flow rotate and enhance the combustion effect. The secondary fan 41 ventilates the mixing chamber 3 and mixes with the high-temperature flue gas, which then enters the pulverized coal boiler 6 to assist combustion. The pulverized coal boiler 6 includes a secondary air box 7. The secondary air box 7 of the pulverized coal boiler 6 is connected to the rear secondary air duct 5. The bottom surface of the secondary air box 7 is provided with a number of ash hoppers 71 for ash discharge by welding. The specific number is not limited and is set according to the size of the secondary air box 7. The ash hopper 71 is welded with steel plates. The ash hopper 71 is provided with an ash discharge valve 711. The ash discharge valve 711 can be an electric gate valve and is fixed at the outlet of the ash hopper 71 by bolts. The secondary air box 7 blows ash regularly.

[0045] Reference Figure 1 The cross-section of the secondary air box 7 is larger than that of the second two air ducts 5. After the high-temperature flue gas enters the secondary air box 7, its speed will decay rapidly. The large-diameter ash particles carried by the high-temperature flue gas will fall into the ash hopper 71 of the secondary air box 7 due to gravity.

[0046] Reference Figure 1 After the pulverized coal boiler 6 starts to burn stably, the adiabatic furnace 1 begins to operate; before the pulverized coal boiler 6 is shut down, the adiabatic furnace 1 is shut down in advance; the pulverized coal boiler 6 is shut down due to an accident, and the primary fan 12 is turned off.

[0047] The implementation principle of the embodiment of this application is:

[0048] First, a fuel, such as pebble coal with a particle size no larger than 10 mm, is fed into adiabatic furnace 1 for complete combustion. Auxiliary fan 14, working in conjunction with primary fan 12 via auxiliary air duct 13, precisely regulates the amount of air entering adiabatic furnace 1, controlling the intensity of fuel combustion and ensuring that adiabatic furnace 1's maximum heat output per unit time is no greater than 10% of the maximum heat output per unit time of pulverized coal boiler 6.

[0049] Fuel combustion in adiabatic furnace 1 generates high-temperature flue gas, which carries ash particles upward and enters gas-solid separation device 2. The separated high-temperature flue gas enters flue duct 21, where its temperature is between 400°C and 900°C. A portion of the low-temperature flue gas flows back into adiabatic furnace 1 through circulation duct 211 and circulation valve 212, participating in the fuel combustion process.

[0050] The high-temperature flue gas in the flue 21 enters the mixing chamber 3. At the same time, the secondary fan 41 supplies air to the mixing chamber 3 through the first two air ducts 4; the guide plate 31 and the spoiler fan 32 in the mixing chamber 3 make the high-temperature flue gas and air fully and evenly mixed to form secondary air with appropriate temperature and flow.

[0051] The mixed secondary air enters the secondary air box 7 through the secondary air duct 5. Because the cross-section of the secondary air box 7 is larger than that of the secondary air duct 5, the secondary air's velocity decreases rapidly upon entering the secondary air box 7. Large-diameter ash particles carried in the high-temperature flue gas settle under gravity into the ash hopper 71 and are periodically discharged through the ash discharge valve 711. The purified and flow-adjusted secondary air ultimately enters the pulverized coal boiler 6, optimizing its combustion conditions and improving combustion efficiency.

[0052] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. An adiabatic furnace high temperature flue gas combustion pulverized coal boiler system, characterized by: The invention comprises an adiabatic furnace (1) mainly using pebble coal as fuel and a secondary air blower (41); the bottom surface of the adiabatic furnace (1) is connected to a primary air duct (11); the end of the primary air duct (11) away from the adiabatic furnace (1) is provided with a primary air blower (12) for ventilating the inside of the adiabatic furnace (1); the top of the adiabatic furnace (1) is connected to a gas-solid separation device (2); the outlet of the gas-solid separation device (2) is provided with a flue (21); the high-temperature flue gas generated by the combustion of pebble coal in the adiabatic furnace (1) is dust-removed by the gas-solid separation device (2) and then flows into the adiabatic furnace (1). The flue (21) is provided with a first two-stage air duct (4) at the output end of the secondary fan (41), and the first two-stage air duct (4) is provided with an air mixing chamber (3). The end of the flue (21) away from the gas-solid separation device (2) is connected to the air mixing chamber (3); the air mixing chamber (3) is connected with a second two-stage air duct (5), and the end of the second two-stage air duct (5) away from the air mixing chamber (3) is provided with a pulverized coal boiler (6). The secondary fan (41) ventilates the air mixing chamber (3) and mixes with the high-temperature flue gas, and then enters the pulverized coal boiler (6) to assist combustion.

2. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 1, characterized in that: The adiabatic furnace (1) is located above the primary air duct (11) and is connected to an auxiliary air duct (13). The auxiliary air duct (13) is provided with an auxiliary fan (14) for cooperating with the primary fan (12) to adjust the amount of smoke generated by the adiabatic furnace (1).

3. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 2, characterized in that: When the pulverized coal boiler (6) is under low load and needs to intensify combustion, the ventilation volume of the auxiliary fan (14) is increased, the combustion of the adiabatic furnace (1) is intensified, and the amount of high-temperature flue gas is increased.

4. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 2, characterized in that: The high-temperature flue gas in the flue (21) has a temperature range of 400° C. to 900° C. The flue (21) is connected to the adiabatic furnace (1) and is provided with a circulation channel (211) for circulating the low-temperature flue gas. The flue (21) is provided with a circulation valve (212).

5. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 1, characterized in that: A plurality of guide plates (31) and a plurality of fixed spoiler fans (32) are provided in the mixing chamber (3); the flue (21) is provided on one side of the mixing chamber (3) and upstream of the guide plates (31); the spoiler fans (32) are located downstream of the guide plates (31); the plurality of guide plates (31) are arranged in sequence obliquely upward along the direction of high-temperature flue gas flow in the flue (21); the guide plates (31) are arranged obliquely so that the high-temperature flue gas flows upward after being guided by the guide plates (31); the high-temperature flue gas is mixed with the air in the first two air ducts (4) arranged in the up-down direction and then enters the second two air ducts through the guide plates (31) and the spoiler fans (32).

6. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 5, characterized in that: The line connecting the bottom ends of the guide plates (31) forms an angle of 4.5-5.5° with the horizontal line, and the angle between the guide plates (31) and the direction of high-temperature flue gas flow in the flue (21) is no greater than 30°.

7. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 1, characterized in that: The pulverized coal boiler (6) includes a secondary wind box (7), the secondary wind box (7) of the pulverized coal boiler (6) is connected to the rear two air ducts (5), a plurality of ash hoppers (71) for ash discharge are provided on the bottom surface of the secondary wind box (7), the ash hoppers (71) are provided with ash discharge valves (711), and the secondary wind box (7) performs ash blowing at regular intervals.

8. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 7, characterized in that: The cross section of the secondary air box (7) is larger than the cross section of the second and second air ducts (5).

9. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 3, characterized in that: The maximum heat output per unit time of the fuel of the adiabatic furnace (1) is no greater than 10% of the maximum heat output per unit time of the pulverized coal boiler (6).

10. The adiabatic furnace high temperature flue gas combustion pulverized coal boiler system according to claim 1, characterized in that: After the pulverized coal boiler (6) starts to burn stably, the adiabatic furnace (1) begins to operate; before the pulverized coal boiler (6) is shut down, the adiabatic furnace (1) is shut down in advance; when the pulverized coal boiler (6) is shut down due to an accident, the primary fan (12) is turned off.

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