A wind-assisted heating system and operation method for a coal-fired power plant startup process

Abstract

The present invention relates to the technical field of energy-saving startup of coal-fired power plants, and specifically to an auxiliary air heating system and operating method for the startup process of a coal-fired power plant. The system includes: a primary air heating channel, which is connected to a coal mill after passing through an air preheater and an air heater in sequence, a primary air auxiliary channel is connected to the primary air heating channel, and the other end of the primary air auxiliary channel is connected to the coal mill; a secondary air heating channel, which is connected to a boiler body after passing through an air preheater and an air heater in sequence, a secondary air auxiliary channel is connected to the secondary air heating channel, and the other end of the secondary air auxiliary channel is connected to the boiler body. The heat of the coal flue gas and steam is used to heat the primary air and then preheat the coal mill, and the heat of the coal flue gas is used to heat the secondary air and then pass it into the boiler body. This can shorten the consumption of auxiliary fuel during system startup, shorten the time required for the system to start up and operate normally, and reduce the startup cost and startup energy consumption of the coal-fired power plant.

Description

Technical Field

[0001] The present invention relates to the technical field of energy-saving startup of coal-fired power plants, and in particular to an air-assisted heating system and an operating method during the startup process of a coal-fired power plant. Background Art

[0002] With the development of renewable energy, the proportion of renewable energy used for power generation is increasing, negatively impacting the stability of the power grid. Consequently, the grid has placed higher demands on the peak-shaving capabilities of coal-fired power plants, leading to a significant increase in the number of unit starts and stops throughout the year. Ball mills are the primary equipment for processing coal in thermal power plants. While these mills have high output and a high level of pulverized coal stored in the mill, the frequent and lengthy unit startups lead to significant consumption of the auxiliary fuel oil used for boiler startup, further increasing startup costs and energy consumption for coal-fired power plants. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect of high startup energy consumption of coal-fired power plants in the prior art, thereby providing an air-assisted heating system and operation method for the startup process of a coal-fired power plant.

[0004] In order to solve the above technical problems, the present invention provides an air-assisted heating system for the startup process of a coal-fired power plant, comprising:

[0005] The boiler body has a coal mill installed at the burner inlet end, and the coal mill is connected to the primary air channel;

[0006] an air feed heater, the hot side of which is connected to the steam outlet end of the boiler body;

[0007] an air preheater, the hot side of which is connected to the flue gas outlet of the boiler body;

[0008] Also includes:

[0009] The primary air heating channel passes through the cold side of the air preheater and the cold side of the air supply heater in sequence and is connected to the coal mill. The primary air heating channel between the air preheater and the air supply heater is connected to a primary air auxiliary channel, and the other end of the primary air auxiliary channel is connected to the coal mill.

[0010] The secondary air heating channel passes through the cold side of the air preheater and the cold side of the air feed heater in sequence and is connected to the burner inlet end of the boiler body. The secondary air heating channel between the air preheater and the air feed heater is connected to a secondary air auxiliary channel, and the other end of the secondary air auxiliary channel is connected to the burner inlet end of the boiler body.

[0011] Optionally, the primary air heating channel and the secondary air heating channel share the same channel in the air supply heater.

[0012] Optionally, the steam outlet end of the boiler body is further connected to a bypass channel, and the bypass channel is connected to the reheater.

[0013] Optionally, the steam outlet end of the boiler body is further connected to a steam inlet channel, the steam inlet channel is connected to the steam inlet end of the steam turbine unit, and the steam outlet end of the steam turbine unit is connected to the reheater.

[0014] Optionally, the inlet end and the outlet end of the primary air heating channel are both connected to the primary air channel, and a primary air cooling air damper is installed on the primary air channel between the inlet end and the outlet end of the primary air heating channel.

[0015] The present invention further provides a method for operating air-assisted heating during the startup process of a coal-fired power plant, which is applied to the air-assisted heating system during the startup process of a coal-fired power plant described in the present invention. The method comprises:

[0016] The primary air is controlled to pass through the cold side of the air preheater and the cold side of the air heater in sequence to be heated and then introduced into the coal mill, and the coal mill is preheated by the hot primary air;

[0017] Obtain the outlet flue gas temperature at the flue gas outlet end of the boiler body and determine whether the outlet flue gas temperature is greater than the set temperature. If it is, control the secondary air to pass through the cold side of the air preheater in sequence to be heated and then introduced into the boiler body.

[0018] Optionally, it also includes: obtaining the operating status of the coal mill, judging whether the coal mill has been started; if the coal mill has been started, controlling the primary air to be heated through the cold side of the air preheater in sequence and then directly passed into the coal mill; at the same time, controlling the secondary air to be heated through the cold side of the air preheater and the cold side of the air heater in sequence and then passed into the boiler body, thereby increasing the temperature of the secondary air entering the boiler body.

[0019] Optionally, the steam inlet amount of the air feed heater and the steam inlet amount of the bypass channel are obtained, and it is judged whether the steam inlet amount of the air feed heater (8) is less than a first preset steam inlet amount, and at the same time, it is judged whether the steam inlet amount of the bypass channel is less than a second preset steam inlet amount; when the steam inlet amount of the air feed heater (8) is less than the first preset steam inlet amount, and / or the steam inlet amount of the bypass channel is less than the second preset steam inlet amount, the boiler body is controlled not to supply steam to the air feed heater, and at the same time, the primary air is controlled to be heated in sequence through the cold side of the air preheater and then directly supplied to the coal mill, and the secondary air is controlled to be heated in sequence through the cold side of the air preheater and then directly supplied to the boiler body.

[0020] Optionally, it also includes controlling the primary temperature of air entering the coal mill to not exceed 100°C, and controlling the secondary air temperature entering the boiler body to not exceed 330°C.

[0021] Optionally, the opening of the primary air cooling air damper is controlled to control the temperature of the primary air entering the coal mill to not exceed 100°C.

[0022] The technical solution of the present invention has the following advantages:

[0023] 1. The air supply auxiliary heating system for the startup process of a coal-fired power plant provided by the present invention comprises: a boiler body, a coal mill is installed at the burner inlet end of the boiler body, and a primary air channel is connected to the coal mill; an air supply heater, a hot side of which is connected to the steam outlet end of the boiler body; an air preheater, a hot side of which is connected to the flue gas outlet end of the boiler body; and further comprises: a primary air heating channel, which is connected to the coal mill after passing through the cold side of the air preheater and the cold side of the air supply heater in sequence, and a primary air auxiliary channel is connected to the primary air heating channel between the air preheater and the air supply heater, and the other end of the primary air auxiliary channel is connected to the coal mill; a secondary air heating channel, which is connected to the burner inlet end of the boiler body after passing through the cold side of the air preheater and the cold side of the air supply heater in sequence, and a secondary air auxiliary channel is connected to the secondary air heating channel between the air preheater and the air supply heater, and the other end of the secondary air auxiliary channel is connected to the burner inlet end of the boiler body.

[0024] By recycling the startup bypass steam that would otherwise be wasted to the feed air heater, and by passing the primary air sequentially into the cold side of the air preheater and the cold side of the feed air heater during system startup, the flue gas and steam generated in the boiler body are used to heat the primary air before passing it into the pulverizer, using the hot primary air to preheat the pulverizer. When the flue gas temperature at the flue gas outlet of the boiler body reaches the set temperature, the secondary air is heated by the air preheater and then passed into the boiler body. By increasing the temperature of the secondary air entering the boiler body, the combustion environment within the boiler body is improved. By using the heat of the flue gas and steam in the boiler body to heat the primary air and then preheat the pulverizer, and then heating the secondary air with the heat of the flue gas before passing it into the boiler body, the consumption of auxiliary fuel during system startup can be greatly reduced, and the time required for the system boiler body and pulverizer to start and operate normally can be shortened, which can greatly reduce the startup cost and startup energy consumption of coal-fired power plants.

[0025] 2. The present invention provides a coal-fired power plant startup air auxiliary heating system. The primary and secondary air heating channels share the same channel within the air heater. This shared piping significantly reduces system piping layout, simplifies the system structure, and reduces system deployment costs.

[0026] 3. The auxiliary air heating system for startup of a coal-fired power plant provided by the present invention features a bypass channel connected to the steam outlet of the boiler, which in turn communicates with the reheater. After the boiler and coal mill are operational, the amount of steam entering the air heater is adjusted by the steam flow through the bypass channel, ensuring the normal operation of the power generation system.

[0027] 4. The method for auxiliary air heating during the startup process of a coal-fired power plant provided by the present invention is applied to the auxiliary air heating system during the startup process of a coal-fired power plant described in the present invention. The method includes: controlling the primary air to pass through the cold side of the air preheater and the cold side of the air heater in sequence to be heated and then passed into the coal mill, and preheating the coal mill with the hot primary air; obtaining the outlet flue gas temperature at the flue gas outlet end of the boiler body, judging whether the outlet flue gas temperature is greater than the set temperature, and if so, controlling the secondary air to pass through the cold side of the air preheater in sequence to be heated and then passed into the boiler body. By utilizing the heat of the flue gas and steam in the boiler body to heat the primary air and then preheat the coal mill, and heating the secondary air with the heat of the flue gas and then passing it into the boiler body, the consumption of auxiliary fuel during system startup can be greatly reduced, and the time required for the system boiler body and coal mill to start and operate normally can also be shortened, which can greatly reduce the startup cost and startup energy consumption of the coal-fired power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a structural schematic diagram of an air-assisted heating system for a coal-fired power plant startup process provided in an embodiment of the present invention.

[0030] Explanation of the accompanying symbols: 1. Coal mill; 2. Burner baffle; 3. Boiler body; 4. Turbine steam inlet valve; 5. Turbine bypass valve; 6. Feed air heating bypass valve; 7. Bypass desuperheater; 8. Feed air heater; 9. Steam turbine unit; 10. Primary air bypass outlet damper; 11. Secondary air bypass outlet damper; 12. Primary air bypass inlet damper; 13. Secondary air bypass inlet damper; 14. Primary air hot air damper; 15. Secondary air damper; 16. Primary air cooling air damper; 17. Secondary fan; 18. Primary fan; 19. Air preheater. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0034] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Example 1

[0036] like Figure 1 The figure shows an air supply auxiliary heating system for the startup process of a coal-fired power plant provided by this embodiment, including: a boiler body 3, an air supply heater 8 and an air preheater 19.

[0037] The coal mill 1 is installed at the burner inlet of the boiler body 3. This is connected to a primary air duct, through which primary air enters the system from the outside. The hot side of the feed air heater 8 is connected to the steam outlet of the boiler body 3. Steam is discharged from the feed air heater 8 and enters the condenser. The hot side of the air preheater 19 is connected to the flue gas outlet of the boiler body 3. A primary fan 18 is installed at the inlet of the primary air duct.

[0038] The primary air heating channel passes through the cold side of the air preheater 19 and the cold side of the air supply heater 8 in sequence and is connected to the coal mill 1. The primary air heating channel between the air preheater 19 and the air supply heater 8 is connected to a primary air auxiliary channel, and the other end of the primary air auxiliary channel is connected to the coal mill 1.

[0039] The secondary air heating channel passes through the cold side of the air preheater 19 and the cold side of the air supply heater 8, and then connects to the burner inlet of the boiler body 3. A secondary air auxiliary channel is connected to the secondary air heating channel between the air preheater 19 and the air supply heater 8, and the other end of the secondary air auxiliary channel is connected to the burner inlet of the boiler body 3. A secondary fan 17 is installed at the inlet of the secondary air heating channel.

[0040] A burner baffle 2 is installed between the pulverizer 1 and the boiler body 3 to control the amount of primary air entering the boiler body 3. The steam outlet end of the boiler body 3 is also connected to a bypass channel, which is connected to the reheater. The steam outlet end of the boiler body 3 is also connected to a steam inlet channel, which is connected to the steam inlet end of the high-pressure cylinder of the steam turbine unit 9, and the steam outlet end of the high-pressure cylinder of the steam turbine unit 9 is connected to the reheater. The steam output from the reheater ultimately enters the condenser. A turbine inlet valve is installed on the air inlet channel, a turbine bypass valve 5 is installed on the bypass channel, and a feed air heater bypass valve 6 is installed on the channel between the boiler body 3 and the feed air heater 8. The amount of steam entering different channels from the boiler body 3 is adjusted by controlling the opening of the turbine inlet valve, the turbine bypass valve 5, and the feed air heater bypass valve 6.

[0041] The primary air heating channel and the secondary air heating channel share the same channel within the air supply heater 8. The inlet and outlet of the primary air heating channel are both connected to the primary air channel, and a primary air cold air damper 16 is installed on the primary air channel between the inlet and outlet of the primary air heating channel. A primary air bypass outlet damper 10 is installed on the primary air heating channel at the outlet end of the air supply heater 8, and a primary air bypass inlet damper 12 is installed on the primary air heating channel between the air supply heater 8 and the air preheater 19. A secondary air bypass outlet damper 11 is installed on the secondary air heating channel at the outlet end of the air supply heater 8, and a secondary air bypass inlet damper 13 is installed on the secondary air heating channel between the air supply heater 8 and the air preheater 19. In order to reduce piping layout, the two ends of the primary air auxiliary channel are respectively connected to the primary air heating channel upstream of the primary air bypass outlet damper 10 and downstream of the primary air bypass inlet damper 12, and a primary air hot air damper 14 is installed on the primary air auxiliary channel. Both ends of the secondary air auxiliary channel are respectively connected to the secondary air heating channel upstream of the secondary air bypass outlet damper 11 and downstream of the secondary air bypass inlet damper 13, and a secondary air damper 15 is installed on the secondary air auxiliary channel.

[0042] The coal-fired power plant startup process feed air auxiliary heating system provided in this embodiment has three branches at the main steam outlet of the boiler body 3. The first branch connects to the steam inlet of the high-pressure cylinder of the steam turbine unit 9 through the turbine steam inlet valve 4. The second branch passes through the turbine bypass valve 5 and the bypass desuperheater 7 in sequence and merges with the steam outlet of the high-pressure cylinder of the steam turbine unit 9. The third branch connects to the feed air heater 8 through the feed air heating bypass valve 6. The flue gas outlet of the boiler body 3 is connected to the flue gas inlet of the air preheater 19. After passing through the primary air fan 18, the primary air is divided into two branches: the cold primary air branch connects to the primary air cooling air damper 16, and the hot primary air branch passes through the primary air passage of the air preheater 19 and connects to the primary air hot air damper 14. The outlet of the primary air hot air damper 14 merges with the outlet of the primary air cold air damper 16 and then connects to the primary air inlet of the coal mill 1. The primary air outlet of the coal mill 1 is connected to the burner of the boiler body 3 through the burner baffle 2. The secondary air passes through the blower and is connected to the secondary air inlet of the air preheater 19. The secondary air outlet of the air preheater 19 is connected to the burner inlet of the boiler body 3 through the secondary air damper 15. The primary air hot air damper 14 is connected in parallel to the branch consisting of the primary air bypass inlet damper 12, the air supply heater 8, and the primary air bypass outlet damper 10. The secondary air damper 15 is connected in parallel to the branch consisting of the secondary air bypass inlet damper 13, the air supply heater 8, and the secondary air bypass outlet damper 11. The outlet of the primary air bypass inlet damper 12 merges with the secondary air bypass inlet damper 13 and is connected to the air supply inlet of the air supply heater 8. The air supply outlet of the air supply heater 8 is connected to the inlets of the primary air bypass outlet damper 10 and the secondary air bypass outlet damper 11, respectively.

[0043] By extracting some steam from the boiler body 3 and inputting it into the air heater 8, the flue gas generated by the combustion of pulverized coal in the boiler body 3 is simultaneously input into the air preheater 19. At system startup, the primary air is sequentially introduced into the cold side of the air preheater 19 and the cold side of the air heater 8. The primary air is heated by the flue gas and steam generated in the boiler body 3 before being introduced into the coal mill 1, where the hot primary air is used to preheat the coal mill 1. When the flue gas temperature at the flue gas outlet of the boiler body 3 reaches the set temperature, the secondary air is heated by the air preheater 19 and then introduced into the boiler body 3. By increasing the temperature of the secondary air entering the boiler body 3, the combustion environment within the boiler body 3 is improved. By utilizing the heat of the flue gas and steam in the boiler body 3 to heat the primary air and then preheat the coal mill 1, and by utilizing the heat of the flue gas to heat the secondary air and then introduce it into the boiler body 3, the consumption of the auxiliary fuel during system startup can be greatly shortened, and the time required for the system boiler body 3 and the coal mill 1 to start up to normal operation can also be shortened, which can greatly reduce the startup cost and startup energy consumption of the coal-fired power plant.

[0044] Example 2

[0045] This embodiment provides a method for operating air-assisted heating during the startup process of a coal-fired power plant, which is applied to the air-assisted heating system during the startup process of the coal-fired power plant described in Example 1. The method includes:

[0046] The system automatically adjusts the openings of the turbine inlet valve, turbine bypass valve 5, and feed air heater bypass valve 6 through PID feedback regulation, thereby adjusting the amount of steam entering different channels from the boiler body 3. During startup, the valve opening signal of the turbine bypass valve 5 is maintained at 5% to 10%. The feed air heater bypass valve 6, primary fan 18, primary air bypass inlet damper 12, primary air bypass outlet damper 10, and burner damper 2 are opened, and the primary air cooling damper 16, primary air hot air damper 14, secondary air bypass inlet damper 13, and secondary air bypass outlet damper 11 are closed. The primary air is controlled to pass through the cold side of the air preheater 19 and the cold side of the feed air heater 8 in sequence, and then is heated and introduced into the coal mill 1, where the hot primary air preheats the coal mill 1.

[0047] The flue gas temperature at the flue gas outlet of boiler body 3 is acquired in real time to determine whether it is greater than the set temperature. If so, the secondary air is heated sequentially through the cold side of air preheater 19 before being introduced into boiler body 3. Air preheater 19 is activated to heat the primary and secondary air, and the primary air hot air damper 14, secondary air damper 15, primary air bypass outlet damper 10, and primary air bypass inlet damper 12 are opened. The primary air bypass inlet damper 12 and primary air hot air damper 14 are adjusted to control the primary air temperature at the inlet of coal mill 1, while the secondary air damper 15 is adjusted to control the secondary air temperature at the inlet of boiler body 3. In this embodiment, the set temperature is 100°C.

[0048] The operating status of the coal mill 1 is obtained in real time to determine whether the coal mill 1 has been started. If the coal mill has been started and put into operation, the primary air is controlled to pass through the cold side of the air preheater 19 in sequence to be heated and then directly introduced into the coal mill 1. At the same time, the secondary air is controlled to pass through the cold side of the air preheater 19 and the cold side of the air heater 8 in sequence to be heated and then introduced into the boiler body 3, thereby increasing the temperature of the secondary air entering the boiler body 3. The primary air bypass outlet damper 10 and the primary air bypass inlet damper 12 are closed, and the secondary air bypass outlet damper 11 and the secondary air bypass inlet damper 13 are opened. By adjusting the secondary air bypass inlet damper 13, the temperature of the secondary air entering the furnace is increased to improve furnace combustion.

[0049] The steam intake amount of the air feed heater 8 and the steam intake amount of the turbine bypass valve 5 are obtained in real time to determine whether the steam intake amount of the air feed heater 8 is less than the first preset intake amount, and at the same time determine whether the steam intake amount of the turbine bypass valve 5 is less than the second preset intake amount; when the steam intake amount of the air feed heater 8 is less than the first preset intake amount, and / or the steam intake amount of the turbine bypass valve 5 is less than the second preset intake amount, the boiler body 3 is controlled to no longer supply steam to the air feed heater 8, and at the same time, the primary air is controlled to be heated in sequence through the cold side of the air preheater 19 and then directly supplied to the coal mill 1, and the secondary air is controlled to be heated in sequence through the cold side of the air preheater 19 and then directly supplied to the boiler body 3. In this embodiment, the valve opening of the air heating bypass valve 6 is used to indicate the steam intake amount of the bypass channel. If the valve instruction of the air heating bypass valve 6 is less than 5%, the air heating bypass valve 6, the primary air bypass outlet damper 10, the secondary air bypass outlet damper 11, the primary air bypass inlet damper 12 and the secondary air bypass inlet damper 13 are closed.

[0050] The control constraints for the air heating bypass valve 6 are to ensure that the valve command of the turbine bypass valve 5 is greater than 5%, that the temperature of the primary air entering the coal mill 1 does not exceed 100°C, and that the temperature of the secondary air entering the boiler body 3 does not exceed 330°C. In this embodiment, the opening of the primary air cooling damper 16 can be controlled to ensure that the primary air temperature entering the coal mill 1 does not exceed 100°C.

[0051] The auxiliary air heating system is used to heat the primary air, which increases the primary air temperature, reduces the preheating time of the coal mill 1, and reduces the consumption of starting fuel oil; the auxiliary air heating system is used to heat the secondary air, which increases the secondary air temperature and improves the stability of boiler combustion; by recovering the heat of the starting bypass and using the air heater 8 to heat the primary air or secondary air, waste heat is utilized and the starting energy consumption of the unit is reduced.

[0052] The wind-assisted heating operation method during the startup process of a coal-fired power plant provided in this embodiment is used to control the rapid startup of the power generation system of the coal-fired power plant. If the outlet flue gas temperature of the boiler body 3 is higher than 100°C, the air preheater 19 is started and the flue gas is used to heat the primary air and secondary air. At this time, the boiler body 3 begins to generate steam. However, since the turbine unit 9 has not yet been started, the steam generated by the boiler body 3 is sent to the reheater after starting the turbine bypass valve 5 and the bypass desuperheater 7, and finally to the condenser. At this time, the feed air heater 8 can be started to recover the starting bypass steam, and the primary air bypass inlet damper 12 and the primary air bypass outlet damper 10 are opened at the same time. By adjusting the primary air hot air damper 14 and the primary air bypass inlet damper 12, the primary air flow entering the feed air heater 8 is controlled, and then the primary air outlet temperature of the feed air heater 8 is controlled. Due to the use of the feed air heater 8, the primary air flow and temperature entering the coal mill 1 are improved, thereby accelerating the preheating process of the coal mill 1, reducing the fuel consumption of the boiler body 3, and reducing the energy consumption during the startup process. During the process of heating the primary air using the air feed heater 8, the valve command of the turbine bypass valve 5 should be greater than 5%. This is to ensure that the turbine bypass valve 5 effectively controls the steam pressure at the outlet of the boiler body 3, and to ensure that steam enters the reheater to prevent dry burning of the reheater. At the same time, the temperature of the primary air entering the coal mill 1 cannot exceed 100°C to prevent the air-powder mixture at the outlet of the coal mill 1 from spontaneous combustion. After the coal mill 1 is started, the primary air bypass outlet damper 10 and the primary air bypass inlet damper 12 are closed, and the secondary air bypass outlet damper 11 and the secondary air bypass inlet damper 13 are opened. By adjusting the secondary air bypass inlet damper 13, the temperature of the secondary air entering the furnace is increased to improve furnace combustion. The temperature of the secondary air cannot exceed 330°C. After the steam turbine unit 9 is started, the steam flow consumed by the steam turbine unit 9 begins to increase rapidly, causing the steam flow entering the turbine bypass valve 5 and the air heating bypass valve 6 to decrease rapidly. Therefore, when the valve instructions of the steam turbine bypass valve 5 and the air heating bypass valve 6 are less than 5%, the steam turbine bypass valve 5 and the air heating bypass valve 6 are closed.

[0053] During the startup process of a coal-fired power plant, the startup bypass steam is recovered and the primary air is heated using the auxiliary air heating system. This increases the primary air temperature, reduces the preheating time of the coal mill 1, and reduces startup fuel consumption. The auxiliary air heating system is used to heat the secondary air, increasing the secondary air temperature and improving the stability of boiler combustion. By using this system and method, the present invention can recover heat from the startup bypass to heat the primary or secondary air, achieving waste heat utilization and reducing the startup energy consumption of the unit.

[0054] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A wind-assisted heating system for the startup process of a coal-fired power plant, characterized in that: include: A boiler body (3) is provided with a coal mill (1) at the burner inlet end thereof, and the coal mill (1) is connected to a primary air channel; an air feed heater (8), the hot side of which is in communication with the steam outlet of the boiler body (3); an air preheater (19), the hot side of which is in communication with the flue gas outlet of the boiler body (3); Also includes: A primary air heating channel is connected to the coal mill (1) after passing through the cold side of the air preheater (19) and the cold side of the air supply heater (8) in sequence; a primary air auxiliary channel is connected to the primary air heating channel between the air preheater (19) and the air supply heater (8); and the other end of the primary air auxiliary channel is connected to the coal mill (1); A secondary air heating channel passes through the cold side of the air preheater (19) and the cold side of the air supply heater (8) in sequence and is connected to the burner inlet end of the boiler body (3); a secondary air auxiliary channel is connected to the secondary air heating channel between the air preheater (19) and the air supply heater (8); the other end of the secondary air auxiliary channel is connected to the burner inlet end of the boiler body (3); The coal-fired power plant startup process air-assisted heating system adopts the following coal-fired power plant startup process air-assisted heating operation method to start operation: The primary air is controlled to pass through the cold side of the air preheater (19) and the cold side of the air supply heater (8) in sequence to be heated and then introduced into the coal mill (1), thereby preheating the coal mill (1) through the hot primary air; Obtain the outlet flue gas temperature of the flue gas outlet end of the boiler body (3), and determine whether the outlet flue gas temperature is greater than the set temperature. If so, control the secondary air to pass through the cold side of the air preheater (19) in sequence to be heated and then pass into the boiler body (3); The operation status of the coal mill (1) is obtained to determine whether the coal mill (1) has been started. If the coal mill (1) has been started, the primary air is controlled to pass through the cold side of the air preheater (19) in sequence to be heated and then directly enter the coal mill (1). At the same time, the secondary air is controlled to pass through the cold side of the air preheater (19) and the cold side of the air heater (8) in sequence to be heated and then enter the boiler body (3), thereby increasing the temperature of the secondary air entering the boiler body (3).

2. The air-assisted heating system for the startup process of a coal-fired power plant according to claim 1, characterized in that: The primary air heating channel and the secondary air heating channel share the same channel in the air supply heater (8).

3. The air-assisted heating system for the startup process of a coal-fired power plant according to claim 1 or 2, characterized in that: The steam outlet end of the boiler body (3) is also connected to a bypass channel, and the bypass channel is connected to the reheater.

4. The air-assisted heating system for the startup process of a coal-fired power plant according to claim 3, characterized in that: The steam outlet end of the boiler body (3) is also connected to a steam inlet channel, the steam inlet channel is connected to the steam inlet end of the steam turbine unit (9), and the steam outlet end of the steam turbine unit (9) is connected to the reheater.

5. The air supply auxiliary heating system for the startup process of a coal-fired power plant according to any one of claims 1 to 4, characterized in that: The inlet end and the outlet end of the primary air heating channel are both connected to the primary air channel, and a primary air cooling air damper (16) is installed on the primary air channel between the inlet end and the outlet end of the primary air heating channel.

6. The air-assisted heating system for the startup process of a coal-fired power plant according to claim 1, characterized in that: The steam inlet amount of the air heater (8) and the steam inlet amount of the bypass channel are obtained, and it is judged whether the steam inlet amount of the air heater (8) is less than a first preset steam inlet amount, and at the same time, it is judged whether the steam inlet amount of the bypass channel is less than a second preset steam inlet amount; when the steam inlet amount of the air heater (8) is less than the first preset steam inlet amount, and / or the steam inlet amount of the bypass channel is less than the second preset steam inlet amount, the boiler body (3) is controlled to no longer supply steam to the air heater (8), and at the same time, the primary air is controlled to pass through the cold side of the air preheater (19) in sequence to be heated and then directly pass into the coal mill (1), and the secondary air is controlled to pass through the cold side of the air preheater (19) in sequence to be heated and then directly pass into the boiler body (3).

7. The air supply auxiliary heating system for the startup process of a coal-fired power plant according to claim 1, characterized in that: It also includes controlling the primary air temperature entering the coal mill (1) to not exceed 100°C, and controlling the secondary air temperature entering the boiler body (3) to not exceed 330°C.

8. The air supply auxiliary heating system for the startup process of a coal-fired power plant according to claim 7, characterized in that: The opening of the primary air cooling air damper (16) is controlled to control the temperature of the primary air entering the coal mill (1) to not exceed 100°C.

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