Coal-fired boiler pulverized coal supply system capable of improving burnout property of pulverized coal

Abstract

The coal-fired boiler pulverized coal supply system comprises a coal mill, a plurality of pulverized coal conveying pipes communicated with a boiler combustion chamber are arranged on the coal mill, a sleeve heat exchanger is arranged on the peripheries of the pulverized coal conveying pipes in a sealed mode, and spiral flow deflectors are arranged on the inner wall of the sleeve heat exchanger. One end of the sleeve heat exchanger is communicated with a high-temperature steam supply pipe or a superheated steam output pipe of a boiler outlet through a steam input pipeline provided with a sleeve heat exchanger inlet adjusting valve, and the other end of the sleeve heat exchanger is communicated with a low-temperature steam output pipe through an output pipeline provided with a sleeve heat exchanger outlet isolating valve. The output end of the low-temperature steam output pipe is connected with a first high-pressure heater of the steam turbine, a to-be-heated medium inlet of the first high-pressure heater of the steam turbine is connected with a low-temperature water supply pipe, and a heating medium outlet of the first high-pressure heater of the steam turbine is connected with the high-pressure heater through a pipeline. An outlet of the high-pressure heater is connected with a heat exchange pipe on the inner wall of the boiler through a high-temperature water supply pipe.

Description

Technical Field

[0001] The utility model relates to the technical field of energy-saving of coal-fired boilers, in particular to a coal powder supply system for a coal-fired boiler that improves the burnout performance of coal powder. Background Art

[0002] Coal mills are high-energy-consuming equipment in the entire coal-fired power plant. Reducing the power consumption of coal mills can effectively improve the economy of the entire plant. In addition, the higher the temperature of the primary air entering the boiler, the more stable the combustion in the boiler, and the better the burnout of the coal powder, which is beneficial to improve the combustion efficiency of the boiler, while reducing the exhaust temperature, improving the boiler efficiency, and improving the economy. For example, as described in the patent application 202311682170.8, a lignite-fired power generation system and operation method with an integrated primary air reheating system, a heater is used to preheat the primary and secondary air at the inlet of the air preheater, so as to increase the air temperature at the inlet of the air preheater and the temperature of the primary air at the inlet of the pulverizing system.

[0003] In addition, the wide load denitrification adopted in the transformation of thermal power units must ensure that the temperature of the denitrification inlet flue gas is maintained above 300°C under low load conditions, so as to ensure the activity of the denitrification catalyst.

[0004] Among all the wide-load denitrification technical solutions for coal-fired units, increasing the feed water temperature is the most direct and effective technical means. According to the characteristics of the high-pressure heater of the coal-fired unit, the outlet feed water temperature of the high-pressure heater is directly proportional to the steam pressure entering the high-pressure heater: the higher the steam pressure entering the high-pressure heater (under the premise of ensuring the safety of the high-pressure heater), the higher the saturation temperature of the steam, and the higher the outlet feed water temperature.

[0005] However, in order to achieve the purpose of increasing the temperature of the primary air entering the boiler, there are various technical solutions that can be implemented, not limited to the above-mentioned solutions. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a coal powder supply system for a coal-fired boiler that improves the burnout performance of coal powder.

[0007] In order to solve the above technical problems, the technical solution adopted by the utility model is: a coal-fired boiler coal powder supply system for improving the burnout property of coal powder, including a coal mill, wherein the coal mill is provided with a plurality of powder conveying pipes connected with the boiler combustion chamber, the outer periphery of the powder conveying pipe is sealed with a sleeve heat exchanger, the inner wall of the sleeve heat exchanger is provided with a spiral guide vane, one end of the sleeve heat exchanger is connected with a high-temperature steam supply pipe or a superheated steam output pipe at the boiler outlet through a steam input pipe provided with an inlet regulating valve of the sleeve heat exchanger, the other end of the sleeve heat exchanger is connected with a low-temperature steam output pipe through an output pipe provided with an outlet isolation valve of the sleeve heat exchanger, the output end of the low-temperature steam output pipe is connected with a No. 1 high-pressure heater of the steam turbine, the inlet of the medium to be heated of the No. 1 high-pressure heater of the steam turbine is connected with a low-temperature feed water pipe, the heating medium outlet of the No. 1 high-pressure heater of the steam turbine is connected with the high-pressure heater through a pipeline, and the outlet of the high-pressure heater is connected with the heat exchange pipe on the inner wall of the boiler through the high-temperature feed water pipe.

[0008] As a preferred solution, it also includes a spare coal mill, which is also provided with a plurality of powder conveying pipes connected to the boiler combustion chamber. A sleeve heat exchanger is sealed on the outer periphery of the powder conveying pipe, and a spiral guide vane is provided on the inner wall of the sleeve heat exchanger. One end of the sleeve heat exchanger is connected to the high-temperature steam supply pipe or the superheated steam output pipe at the boiler outlet through a steam input pipe with an inlet regulating valve of the sleeve heat exchanger, and the other end of the sleeve heat exchanger is connected to the low-temperature steam output pipe through an output pipe with an outlet isolation valve of the sleeve heat exchanger, and the output end of the low-temperature steam output pipe is connected to the No. 1 high-pressure heater of the steam turbine.

[0009] As a preferred solution, all ends of the steam input pipelines are gathered on an input main pipe to be connected to a high-temperature steam supply pipe, and an inlet steam isolation valve is provided on the input main pipe.

[0010] As a preferred solution, the ends of all the output pipelines are gathered on an output main pipe to be connected to the low-temperature steam output pipe, and an outlet steam isolation valve is provided on the output main pipe.

[0011] As a preferred solution, when the steam input pipeline is connected to the high-temperature steam supply pipe, the low-temperature steam output pipe is connected to the No. 5 low-pressure heater of the steam turbine through a low-temperature branch pipe, the heating medium outlet of the No. 5 low-pressure heater of the steam turbine is connected to the deaerator through a pipeline, the outlet of the deaerator is connected to the No. 1 high-pressure heater of the steam turbine through a pipeline, the low-temperature medium inlet of the No. 5 low-pressure heater of the steam turbine is connected to the low-pressure heater through a pipeline, and the low-pressure heater is connected to the low-temperature feed water pipe.

[0012] As a preferred solution, the steam input pipeline is connected to the superheated steam output pipe at the boiler outlet through a bypass superheated steam pipe that bypasses the superheated steam pressure reducing valve. The superheated steam output pipe is connected to the high-pressure cylinder of the steam turbine. A steam extraction pipe is provided on the high-pressure cylinder of the steam turbine. A steam extraction isolation valve is provided on the steam extraction pipe. The opening and closing states of the steam extraction isolation valve and the sleeve heat exchanger outlet isolation valve are opposite. The steam extraction pipe is connected to the No. 1 high-pressure heater of the steam turbine.

[0013] The beneficial effects of the utility model are:

[0014] A sleeve heat exchanger is installed on each primary air duct at the outlet of each coal mill, and a spiral guide vane is arranged between the sleeve heat exchanger and the primary air duct; hot steam is introduced into the sleeve heat exchanger, where it flows in the direction of the spiral guide vane and heats the cold primary air at the outlet of the coal mill through the sleeve heat exchanger, and the steam after releasing heat returns to the No. 1 high-pressure heater of the steam turbine; on the one hand, the temperature of the primary air entering the boiler is increased, the combustion stability and coal powder burnout in the boiler are improved, while the exhaust gas temperature is reduced and the boiler efficiency is improved; on the other hand, the air volume entering the coal mill is reduced, the ventilation resistance of the coal mill is reduced, the plant power consumption rate is reduced, and the economy of the unit is improved; thirdly, the feed water temperature entering the boiler is increased, thereby increasing the inlet flue gas temperature of denitrification and ensuring the stable operation of the SCR catalyst under low-load conditions of the unit.

[0015] Since the steam input pipeline is connected with the superheated steam output pipe at the boiler outlet through a bypass superheated steam pipe of a bypass superheated steam pressure reducing valve, the superheated steam output pipe is connected to the high-pressure cylinder of the steam turbine, a steam extraction pipe is provided on the high-pressure cylinder of the steam turbine, a steam extraction isolation valve is provided on the steam extraction pipe, the opening and closing states of the steam extraction isolation valve and the sleeve heat exchanger outlet isolation valve are opposite, and the steam extraction pipe is connected to the No. 1 high-pressure heater of the steam turbine; the original steam extraction isolation of the No. 1 high-pressure heater of the steam turbine, due to the increase in the steam pressure entering the No. 1 high-pressure heater of the steam turbine, the feed water temperature at the outlet of the No. 1 high-pressure heater of the steam turbine also increases.

[0016] When the steam input pipeline is connected to the high-temperature steam supply pipe, the low-temperature steam output pipe is connected to the No. 5 low-pressure heater of the steam turbine through the low-temperature branch pipe, the heating medium outlet of the No. 5 low-pressure heater of the steam turbine is connected to the deaerator through the pipeline, the outlet of the deaerator is connected to the No. 1 high-pressure heater of the steam turbine through the pipeline, the low-temperature medium inlet of the No. 5 low-pressure heater of the steam turbine is connected to the low-pressure heater through the pipeline, and the low-pressure heater is connected to the low-temperature feed water pipe. The low-pressure extraction steam required by the high-pressure cylinder of the steam turbine can be introduced into the sleeve heat exchanger, and the steam flows in the sleeve heat exchanger in the direction of the spiral guide vane. The steam after heat release returns to the No. 5 low-pressure heater of the steam turbine, and then enters the boiler after passing through the deaerator and the No. 1 high-pressure heater of the steam turbine. According to the characteristics of the high-pressure heater of the coal-fired unit, the outlet feed water temperature of the high-pressure heater is proportional to the steam pressure entering the high-pressure heater: the higher the steam pressure entering the high-pressure heater (under the premise of ensuring the safety of the high-pressure heater), the higher the saturation temperature of the steam, and the higher the outlet feed water temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the fluid transmission structure of Example 1 of the utility model.

[0018] Figure 2 It is a schematic diagram of the coal powder conveying structure in the utility model.

[0019] Figure 3 It is a structural schematic diagram of the sleeve heat exchanger in the utility model.

[0020] Figure 4 It is a schematic diagram of the cross-sectional structure of the sleeve heat exchanger of the utility model.

[0021] Figure 5 This is a schematic diagram of the fluid transmission structure of Example 2 of the utility model.

[0022] In the figure: 1. Superheated steam output pipe; 2. Bypass superheated steam pipe; 3. Main superheated steam; 4. Steam turbine high-pressure cylinder; 5. Bypass superheated steam pressure reducing valve; 6. Steam input pipeline; 7. Inlet steam isolation valve; 8. Inlet regulating valve of sleeve heat exchanger; 9. Outlet isolation valve of sleeve heat exchanger; 10. Outlet steam isolation valve; 11. Low-temperature steam output pipe; 12. First-stage steam extraction pipe; 13. First-stage steam extraction isolation valve; 14. High-temperature water supply pipe; 15. Coal mill; 15-1, 15-2, 15-3, 15-4, powder conveying pipe; 15-4- 1. 15-4-2, 15-4-3, 15-4-4, sleeve heat exchanger; 16. Standby coal mill; 16-1, 16-2, 16-3, 16-4, powder conveying pipe; 16-4-1, 16-4-2, 16-4-3, 16-4-4, sleeve heat exchanger; 17. Low-temperature feed water pipe; 18. No. 1 high-pressure heater of steam turbine; 19. Spiral guide vane; 20. Low-temperature primary air duct; 21. High-temperature primary air duct; 22. Boiler, 23. Low-pressure heater; 24. Deaerator; 25. No. 5 low-pressure heater of steam turbine. DETAILED DESCRIPTION

[0023] The specific implementation scheme of the utility model is described in detail below in conjunction with the accompanying drawings.

[0024] like Figure 1-4 As shown, a pulverized coal supply system for a coal-fired boiler for improving the burnout performance of pulverized coal includes a coal mill 15, wherein the coal mill 15 is provided with a plurality of pulverized coal conveying pipes 15-1, 15-2, 15-3, and 15-4 connected to a combustion chamber of a boiler 22, wherein sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3, and 15-4 are sealed on the outer periphery of the pulverized coal conveying pipes 15-1, 15-2, 15-3, and 15-4, and the sleeve heat exchangers 15-4-1 The inner walls of 15-4-2, 15-4-3 and 15-4-4 are provided with spiral guide vanes 19. One end of the sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3 and 15-4-4 is connected to the superheated steam output pipe 1 at the boiler outlet through the steam input pipe 6 provided with the sleeve heat exchanger inlet regulating valve 8 and the bypass superheated steam pipe 2 provided with the bypass superheated steam pressure reducing valve 5. The superheated steam output pipe 1 is connected to the high-pressure cylinder 4 of the steam turbine.

[0025] The other end of the sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3, and 15-4-4 is connected to the low-temperature steam output pipe 11 through the output pipe of the sleeve heat exchanger outlet isolation valve 9, and the end of the low-temperature steam output pipe 11 is connected to the No. 1 high-pressure heater 18 of the steam turbine. The inlet of the medium to be heated of the No. 1 high-pressure heater 18 of the steam turbine is provided with a low-temperature feed water pipe 17, and the outlet of the heating medium of the No. 1 high-pressure heater 18 of the steam turbine is connected to the high-pressure heater 23 through a pipeline, and the outlet of the high-pressure heater 23 is connected to the heat exchange pipe on the inner wall of the boiler 22 through the high-temperature feed water pipe 14.

[0026] The utility model also includes a standby coal mill 16, which is also provided with a plurality of powder conveying pipes 16-1, 16-2, 16-3, 16-4 connected to the combustion chamber of the boiler 22. The outer periphery of the powder conveying pipes 16-1, 16-2, 16-3, 16-4 is sealed with sleeve heat exchangers 16-4-1, 16-4-2, 16-4-3, 16-4-4. The inner wall of the sleeve heat exchangers 16-4-1, 16-4-2, 16-4-3, 16-4-4 is provided with spiral guide vanes 19. One end of 16-4-1, 16-4-2, 16-4-3, and 16-4-4 is connected to the high-temperature steam supply pipe or the superheated steam output pipe at the boiler outlet through the steam input pipeline of the sleeve heat exchanger inlet regulating valve 8, and the other end of the sleeve heat exchanger 16-4-1, 16-4-2, 16-4-3, and 16-4-4 is connected to the low-temperature steam output pipe 11 through the output pipeline of the sleeve heat exchanger outlet isolation valve 9, and the end of the low-temperature steam output pipe 11 is connected to the No. 1 high-pressure heater 18 of the steam turbine.

[0027] The ends of all the steam input pipelines are gathered to the input main pipe to be connected to the high-temperature steam supply pipe, and the input main pipe is provided with an inlet steam isolation valve 7. The ends of all the output pipelines are gathered to the output main pipe to be connected to the low-temperature steam output pipe 11, and the output main pipe is provided with an outlet steam isolation valve 10.

[0028] A steam extraction pipe 12 is provided on the high-pressure cylinder 4 of the steam turbine, and a steam extraction isolation valve 13 is provided on the steam extraction pipe 12. The opening and closing states of the steam extraction isolation valve 13 and the sleeve heat exchanger outlet isolation valve 9 are opposite. The steam extraction pipe 12 is connected to the No. 1 high-pressure heater 18 of the steam turbine.

[0029] During operation, the superheated steam is divided into bypass superheated steam and main superheated steam 3. The main superheated steam 3 is sent to the high-pressure cylinder 4 of the steam turbine to perform work; the bypass superheated steam is reduced in pressure by the bypass superheated steam pressure reducing valve 5 and becomes low-pressure bypass superheated steam;

[0030] The low-pressure bypass superheated steam passes through the sleeve heat exchanger inlet isolation valve 7 and then the sleeve heat exchanger inlet regulating valve 8 for flow regulation, and then enters the sleeve heat exchanger and flows in a spiral direction along the spiral guide vane 17 in the sleeve heat exchanger, and finally becomes low-temperature steam; the outlets of the coal mill 15 and the standby coal mill 16 are connected in parallel with the sleeve heat exchangers on the primary air duct;

[0031] The low-temperature steam continues to enter the No. 1 high-pressure heater 18, the first stage extraction steam isolation valve 13 is closed, and the first stage extraction steam is in an isolation state; the low-temperature steam heats the low-temperature feed water through the No. 1 high-pressure heater 18, and the low-temperature feed water heated by the No. 1 high-pressure heater 18 becomes high-temperature feed water and is finally sent to the boiler 22;

[0032] The low-temperature primary air at the outlet of the coal mill 15 and the standby coal mill 16 is heated to become high-temperature primary air, and is finally sent to the boiler 22 for combustion.

[0033] The low-temperature primary air and low-pressure bypass superheated steam conduct countercurrent heat transfer in the sleeve heat exchanger.

[0034] Example 2 Figure 2-5 As shown, a pulverized coal supply system for a coal-fired boiler for improving the burnout performance of pulverized coal includes a coal mill 15, wherein the coal mill 15 is provided with a plurality of pulverized coal conveying pipes 15-1, 15-2, 15-3, and 15-4 connected to a combustion chamber of a boiler 22, wherein sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3, and 15-4 are sealed on the outer periphery of the pulverized coal conveying pipes 15-1, 15-2, 15-3, and 15-4, and the sleeve heat exchangers 15-4-1 Spiral guide vanes 19 are provided on the inner walls of 15-4-2, 15-4-3 and 15-4-4. One end of the sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3 and 15-4-4 is connected to the superheated steam output pipe 1 at the boiler outlet through the steam input pipe 6 provided with the sleeve heat exchanger inlet regulating valve 8 and the bypass superheated steam pipe 2 provided with the bypass superheated steam pressure reducing valve 5. The superheated steam output pipe 1 is connected to the turbine high-pressure cylinder 4.

[0035] The other end of the sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3, and 15-4-4 is connected to the low-temperature steam output pipe 11 through the output pipe of the sleeve heat exchanger outlet isolation valve 9. The low-temperature steam output pipe 11 is connected to the No. 5 low-pressure heater 25 of the steam turbine through a low-temperature branch pipe. The heating medium outlet of the No. 5 low-pressure heater 25 of the steam turbine is connected to the deaerator 24 through a pipe. The outlet of the deaerator 24 is connected to the No. 1 high-pressure heater 18 of the steam turbine through a pipe. The outlet of the high-pressure heater 23 is connected to the boiler 22 through a pipe. The low-temperature medium inlet of the No. 5 low-pressure heater 25 of the steam turbine is connected to the low-pressure heater 23 through a pipe. The low-pressure heater 23 is connected to the low-temperature feed water pipe 17.

[0036] The utility model also includes a standby coal mill 16, which is also provided with a plurality of powder conveying pipes 16-1, 16-2, 16-3, 16-4 connected to the combustion chamber of the boiler 22. The outer periphery of the powder conveying pipes 16-1, 16-2, 16-3, 16-4 is sealed with sleeve heat exchangers 16-4-1, 16-4-2, 16-4-3, 16-4-4. The inner wall of the sleeve heat exchangers 16-4-1, 16-4-2, 16-4-3, 16-4-4 is provided with spiral guide vanes 19. One end of 16-4-1, 16-4-2, 16-4-3, and 16-4-4 is connected to the high-temperature steam supply pipe or the superheated steam output pipe at the boiler outlet through the steam input pipeline of the sleeve heat exchanger inlet regulating valve 8, and the other end of the sleeve heat exchanger 16-4-1, 16-4-2, 16-4-3, and 16-4-4 is connected to the low-temperature steam output pipe 11 through the output pipeline of the sleeve heat exchanger outlet isolation valve 9, and the end of the low-temperature steam output pipe 11 is connected to the No. 1 high-pressure heater 18 of the steam turbine.

[0037] The ends of all the steam input pipelines are gathered to the input main pipe to be connected to the high-temperature steam supply pipe, and the input main pipe is provided with an inlet steam isolation valve 7. The ends of all the output pipelines are gathered to the output main pipe to be connected to the low-temperature steam output pipe 11, and the output main pipe is provided with an outlet steam isolation valve 10.

[0038] In the working process of the pulverized coal supply system of this embodiment, taking the pulverized coal conveying pipes 15-1, 15-2, 15-3, 15-415-1 of the coal mill as an example, the high-temperature steam enters the pulverized coal conveying pipes 15-1, 15-2, 15-3, 15-4 and the pulverized coal conveying pipes 15-4-1, 15-4-2, 15-4-3, 15-4-4 after passing through the sleeve heat exchanger inlet regulating valve 8, and -3, 15-4 sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3, 15-4-4 flow along the arrangement direction of the spiral guide vanes 17, and finally become low-temperature steam; low-temperature primary air and high-temperature steam countercurrently flow heat in the sleeve heat exchangers 15-4-1, 15-4-2, 15-4-3, 15-4-4 of the coal mill powder conveying pipes 15-1, 15-2, 15-3, 15-4, thereby improving the heat transfer performance;

[0039] The low-temperature primary air is heated by the high-temperature steam to become the high-temperature primary air, which is finally sent to the boiler 22 for combustion;

[0040] The low-temperature steam continues to enter the No. 5 low-pressure heater 25 of the steam turbine, and the low-temperature feed water 13 is heated by the low-pressure heater 23, the No. 5 low-pressure heater 25 of the steam turbine, the deaerator 24, and the No. 1 high-pressure heater 18 of the steam turbine in turn to become high-temperature feed water and is sent to the boiler 22.

[0041] The above-mentioned embodiments are only illustrative of the principles and effects of the invention, as well as some embodiments of its application, and are not intended to limit the invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the invention, and all of these belong to the protection scope of the invention.

Claims

1. A pulverized coal supply system for a coal-fired boiler for improving the burnout of pulverized coal, comprising a coal mill, characterized in that: The coal mill is provided with a plurality of powder conveying pipes connected with the combustion chamber of the boiler. A sleeve heat exchanger is sealed on the outer periphery of the powder conveying pipe. A spiral guide vane is provided on the inner wall of the sleeve heat exchanger. One end of the sleeve heat exchanger is connected with a high-temperature steam supply pipe or a superheated steam output pipe at the boiler outlet through a steam input pipe provided with an inlet regulating valve of the sleeve heat exchanger. The other end of the sleeve heat exchanger is connected with a low-temperature steam output pipe through an output pipe provided with an outlet isolation valve of the sleeve heat exchanger. The output end of the low-temperature steam output pipe is connected with the No. 1 high-pressure heater of the steam turbine. The inlet of the medium to be heated of the No. 1 high-pressure heater of the steam turbine is connected with a low-temperature feed water pipe. The heating medium outlet of the No. 1 high-pressure heater of the steam turbine is connected with the high-pressure heater through a pipe. The outlet of the high-pressure heater is connected with the heat exchange pipe on the inner wall of the boiler through the high-temperature feed water pipe.

2. A pulverized coal supply system for a coal-fired boiler for improving the burnout of pulverized coal as claimed in claim 1, characterized in that: It also includes a spare coal mill, which is also provided with a plurality of powder conveying pipes connected with the combustion chamber of the boiler. A sleeve heat exchanger is sealed on the outer periphery of the powder conveying pipe, and a spiral guide vane is provided on the inner wall of the sleeve heat exchanger. One end of the sleeve heat exchanger is connected with the high-temperature steam supply pipe or the superheated steam output pipe at the boiler outlet through a steam input pipe with an inlet regulating valve of the sleeve heat exchanger, and the other end of the sleeve heat exchanger is connected with the low-temperature steam output pipe through an output pipe with an outlet isolation valve of the sleeve heat exchanger, and the output end of the low-temperature steam output pipe is connected with the No. 1 high-pressure heater of the steam turbine.

3. A pulverized coal supply system for a coal-fired boiler for improving the burnout performance of pulverized coal as claimed in claim 2, characterized in that: The ends of all the steam input pipelines are collected on an input main pipe to be connected to a high-temperature steam supply pipe, and an inlet steam isolation valve is provided on the input main pipe.

4. A pulverized coal supply system for a coal-fired boiler for improving the burnout performance of pulverized coal as claimed in claim 3, characterized in that: The ends of all the output pipelines are gathered on an output main pipe to be connected to a low-temperature steam output pipe, and an outlet steam isolation valve is provided on the output main pipe.

5. A pulverized coal supply system for a coal-fired boiler for improving the burnout performance of pulverized coal as claimed in claim 4, characterized in that: When the steam input pipeline is connected to the high-temperature steam supply pipe, the low-temperature steam output pipe is connected to the No. 5 low-pressure heater of the steam turbine through a low-temperature branch pipe, the heating medium outlet of the No. 5 low-pressure heater of the steam turbine is connected to the deaerator through a pipeline, the outlet of the deaerator is connected to the No. 1 high-pressure heater of the steam turbine through a pipeline, the low-temperature medium inlet of the No. 5 low-pressure heater of the steam turbine is connected to the low-pressure heater through a pipeline, and the low-pressure heater is connected to the low-temperature feed water pipe.

6. A pulverized coal supply system for a coal-fired boiler for improving the burnout performance of pulverized coal as claimed in claim 1, characterized in that: The steam input pipeline is connected with the superheated steam output pipe at the boiler outlet through a bypass superheated steam pipe of a bypass superheated steam pressure reducing valve. The superheated steam output pipe is connected to the high-pressure cylinder of the steam turbine. A steam extraction pipe is provided on the high-pressure cylinder of the steam turbine. A steam extraction isolation valve is provided on the steam extraction pipe. The opening and closing states of the steam extraction isolation valve and the sleeve heat exchanger outlet isolation valve are opposite. The steam extraction pipe is connected to the No. 1 high-pressure heater of the steam turbine.

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