Coal-fired unit and its regulating method

Abstract

This invention discloses a coal-fired power unit and its regulation method. The coal-fired power unit includes: a steam boiler unit, a distribution unit, a boiler assembly, an external heating unit, and a control unit. The steam boiler unit has a steam outlet. The distribution unit has a first valve, a first branch, and a second branch. The steam inlet of the first valve is connected to the steam outlet. The first branch is connected to the first outlet of the first valve, and the second branch is connected to the second outlet of the first valve. The primary air duct of the boiler assembly is connected to the first branch, and the secondary air duct is connected to the second branch. A first steam air heater is installed in the primary air duct, and a second steam air heater is installed in the secondary air duct. The external heating unit is connected to the first and second steam air heaters. According to this invention, the coal-fired power unit can effectively prevent blockage and corrosion of the air preheater heat transfer elements, reduce purging frequency and maintenance costs, fundamentally improve low-load combustion conditions, and enable the boiler to maintain efficient combustion even during deep peak shaving.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power technology, and in particular to a coal-fired power unit and a regulation method. Background Technology

[0002] Related technologies indicate that, in the context of energy transition, coal-fired power units need to undertake deep peak-shaving tasks. However, during low-load operation, boiler efficiency declines, leading to a sharp increase in unit coal consumption, severely impacting peak-shaving economics. Traditional technologies such as flue gas bypass and wide-load denitrification can expand the peak-shaving range, but their optimization effect on coal consumption is limited. Meanwhile, the electricity spot market has created numerous zero / low-price periods, providing an opportunity for low-cost peak-shaving retrofits using electricity.

[0003] Existing technologies have attempted to use electric boilers for thermoelectric decoupling, but these are mostly used to produce hot water or steam for direct external supply, failing to achieve deep coupling with the core combustion process of the boiler to directly reduce coal consumption. Furthermore, the utilization of residual heat energy from the steam or hot water produced by such systems after completing a single task is often overlooked, and the overall energy efficiency of the system needs improvement. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a coal-fired unit that can effectively prevent blockage and corrosion of air preheater heat transfer elements, reduce purging frequency and maintenance costs, extend equipment life, fundamentally improve low-load combustion conditions, and enable the boiler to maintain efficient combustion even during deep peak shaving, thereby reducing unit coal consumption.

[0005] This invention also proposes a method for regulating coal-fired power units.

[0006] According to a first aspect of the present invention, a coal-fired power unit includes: a steam boiler unit having a steam outlet; a distribution unit having a first valve, a first branch, and a second branch, wherein the steam inlet of the first valve is connected to the steam outlet, the first branch is connected to a first outlet of the first valve, and the second branch is connected to a second outlet of the first valve; a boiler assembly having a primary air duct and a secondary air duct, wherein the primary air duct is connected to the first branch, the secondary air duct is connected to the second branch, a first steam heater is provided in the primary air duct, and a second steam heater is provided in the secondary air duct; an external heating unit connected to the first steam heater and the second steam heater; and a control unit electrically connected to the steam boiler unit, the distribution unit, the boiler assembly, and the external heating unit.

[0007] According to the coal-fired unit of the present invention, by setting up a steam heater, the wall temperature of the cold end of the air preheater is increased under deep peak shaving and low load conditions, avoiding the condensation of low-temperature corrosive media, effectively preventing blockage and corrosion of the air preheater heat transfer elements, reducing purging frequency and maintenance costs, and extending equipment life; by directly heating the combustion air with high-quality external steam during zero / low electricity price periods, the low-load combustion conditions are improved from the root, enabling the boiler to maintain efficient combustion even during deep peak shaving, thereby reducing the unit's coal consumption.

[0008] In some feasible embodiments, the first steam heater is connected to the external heating unit via a first heating branch, and the second steam heater is connected to the external heating unit via a second heating branch. The control unit is configured to acquire the market electricity price and the peak-shaving demand signal of the coal-fired unit in real time, determine whether the market electricity price is higher than a preset threshold, and control the on / off state of the first branch, and / or the second branch, and / or the first heating branch, and / or the second heating branch.

[0009] In some feasible embodiments, the second branch is provided with a second valve and a first valve, one of which is a pressure regulating valve and the other of which is a shut-off valve.

[0010] In some feasible embodiments, the external heating unit includes: a steam supply network, and the first steam heater and / or the second steam heater are connected to the steam supply network.

[0011] In some feasible embodiments, the external heating unit includes: a heat network heater, with the first steam heater and / or the second steam heater connected to the heat network heater.

[0012] In some feasible embodiments, the control unit is configured to adjust the steam supply flow rate of the steam boiler unit based on the difference between the target air temperature and the real-time air temperature of the boiler assembly.

[0013] In some feasible embodiments, the coal-fired unit further includes a waste heat recovery unit, which is located between the external heating unit and the boiler assembly, and the primary air duct and the secondary air duct are both connected to the collection header of the waste heat recovery unit.

[0014] The adjustment method for a coal-fired power unit according to the second aspect of the present invention, applied to the coal-fired power unit according to the first aspect of the present invention, the adjustment method comprising: Step S1: Obtain the market electricity price and the peak-shaving demand signal of the coal-fired power unit in real time; Step S2: Determine whether the market electricity price is greater than the preset electricity price and whether the coal-fired power unit has a peak-shaving demand signal. If the market electricity price is greater than the preset electricity price, then execute step S1. If the market electricity price is lower than the preset electricity price and the coal-fired power unit has a peak-shaving demand signal, then execute step S3. Step S3: Start the steam boiler unit and introduce steam into the first steam heater and the second steam heater to heat the combustion air to the preset temperature; Step S4: Maintain the combustion air at the preset temperature and reduce the turbine generator load to the target parameter value for deep peak shaving; Step S5: Reduce the pressure of the steam passing through the first steam heater and / or the second steam heater, and introduce it into the external heating unit; Step S6: When the peak shaving end signal is obtained or the market electricity price is greater than the preset electricity price, the steam boiler unit is shut down and step S1 is executed.

[0015] Furthermore, the preset electricity price is a critical economic electricity price calculated based on the operation and maintenance costs of the steam boiler unit and the revenue from ancillary services for deep peak shaving.

[0016] Furthermore, step S3 also includes: acquiring and calculating the difference between the target air temperature and the real-time air temperature of the boiler assembly, and adjusting the output of the steam boiler unit and the steam flow rate of the first branch.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a coal-fired power unit according to an embodiment of the first aspect of the present invention; Figure 2 This is a flowchart of a method for regulating a coal-fired power unit according to a second aspect of the present invention.

[0019] Figure label: 100. Coal-fired power unit; 1. Steam boiler unit; 2. First valve; 3. Second valve; 4. First branch; 5. Second branch; 6. First steam heater; 7. Second steam heater; 8. Boiler assembly; 9. External heating unit; 10. Control unit; 11. Waste heat recovery unit; 12. Pressure reducing unit; A. Market electricity price; B. Peak demand signal. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] The following is for reference. Figure 1 A coal-fired power unit 100 according to an embodiment of the first aspect of the present invention is described.

[0022] like Figure 1 As shown, a coal-fired power unit 100 according to a first aspect embodiment of the present invention includes: a steam boiler unit 1, a distribution unit, a boiler assembly 8, an external heating unit 9, and a control unit 10.

[0023] Specifically, the steam boiler unit 1 has a steam outlet, the distribution unit has a first valve 2, a first branch 4 and a second branch 5, the steam inlet of the first valve 2 is connected to the steam outlet, the first branch 4 is connected to the first outlet of the first valve 2, and the second branch 5 is connected to the second outlet of the first valve 2. The boiler assembly 8 has a primary air duct and a secondary air duct, the primary air duct is connected to the first branch 4, and the secondary air duct is connected to the second branch 5. A first steam heater 6 is installed in the primary air duct, and a second steam heater 7 is installed in the secondary air duct. The external heating unit 9 is connected to the first steam heater 6 and the second steam heater 7. The control unit 10 is electrically connected to the steam boiler unit 1, the distribution unit, the boiler assembly 8 and the external heating unit 9.

[0024] It is understandable that steam boiler unit 1 refers to electrode steam boiler, which can directly convert electrical energy into medium-pressure superheated steam, enabling power plants to proactively take advantage of market opportunities to optimize their own operations; the distribution unit includes first valve 2, first branch 4 and second branch 5. First valve 2 receives steam from steam boiler unit 1 and distributes the steam to two different paths according to control commands. First branch 4 leads to the air duct heater of boiler component 8, and second branch 5 leads to external heating unit 9, thereby realizing intelligent switching and precise control of steam flow direction. During the deep peak shaving stage, priority is given to ensuring steam flow to first branch 4 to heat the combustion air. After completing the main task, it can seamlessly switch to guide the preheated steam to second branch 5 for recycling.

[0025] Furthermore, the boiler assembly 8 has a primary air duct and a secondary air duct. The primary air duct is used to transport primary air carrying pulverized coal, and the secondary air duct is used to transport combustion air. A first steam air heater 6 is installed in the primary air duct, and a second steam air heater 7 is installed in the secondary air duct. This can heat the cold air to the optimal combustion temperature (such as 90°C), improve the combustion stability and efficiency under low load, reduce coal consumption, and increase the air temperature entering the air preheater. This raises the metal wall temperature at the cold end of the air preheater, making it higher than the condensation temperature of ammonium bisulfate, thus solving the problem of air preheater blockage and corrosion during low load operation.

[0026] Furthermore, the external heating unit 9 is connected to the outlet of the first steam heater 6 and the outlet of the second steam heater 7 to receive the steam discharged from the heater that has completed the heat exchange task, realizing the cascade utilization of energy. The waste heat of the steam that might have been wasted is recovered and used for external heating, replacing part of the steam that originally needed to be extracted from the main steam turbine, thereby generating additional economic value and improving the economic efficiency of the coal-fired unit 100. The control unit 10 is electrically connected to the steam boiler unit 1, the distribution unit, the boiler assembly 8 and the external heating unit 9 to send electrical signals to the steam boiler unit 1, the distribution unit, the boiler assembly 8 and the external heating unit 9, and to monitor the electricity spot market price signals and the grid dispatch instructions in real time.

[0027] For example, when the power grid experiences zero / low electricity prices and requires deep peak shaving by the generating units, the control system starts the steam boiler unit 1. The generated medium-pressure superheated steam is first introduced to the first steam heater 6 and the second steam heater 7 to heat the cold air to the optimal combustion temperature. This ensures the combustion stability and efficiency of the boiler components 8 under extremely low loads. Subsequently, the cooled and depressurized steam discharged from the steam heater is introduced to the external heating network for industrial steam supply or heating, realizing the cascade utilization of energy.

[0028] According to an embodiment of the present invention, the coal-fired unit 100, by setting up a steam heater, raises the wall temperature of the cold end of the air preheater under deep peak shaving and low load conditions, avoids the condensation of low-temperature corrosive media, effectively prevents blockage and corrosion of the air preheater heat transfer elements, reduces purging frequency and maintenance costs, and extends equipment life; by directly heating the combustion air with high-quality external steam during zero / low electricity price periods, the low-load combustion conditions are fundamentally improved, enabling the boiler to maintain efficient combustion even during deep peak shaving, thereby reducing the unit's coal consumption.

[0029] In some embodiments of the present invention, such as Figure 1As shown, the first steam heater 6 is connected to the external heating unit 9 via a first heating branch, and the second steam heater 7 is connected to the external heating unit 9 via a second heating branch. The control unit 10 is configured to acquire the market electricity price A and the peak-shaving demand signal B of the coal-fired unit 100 in real time, determine whether the market electricity price A is higher than a preset threshold, and control the on / off state of the first branch 4, and / or the second branch 5, and / or the first heating branch, and / or the second heating branch. It can be understood that during deep peak shaving, priority is given to using steam to heat the combustion air to reduce coal consumption and prevent blockages. Then, the waste heat from each steam source can be efficiently recovered and utilized. By judging the market electricity price A in real time, the coal-fired unit 100 is only started during low electricity prices and deep peak shaving, avoiding energy waste. By setting up the control unit 10, unattended operation is achieved, improving response speed.

[0030] For example, when a coal-fired unit starts up at 100 rpm, the first branch 4 is opened first and the heating branch is closed to ensure that all steam is used for heating the air supply. After the air temperature reaches the standard and the load of the main unit is stable, the heating branch is opened to start waste heat recovery.

[0031] In some embodiments of the present invention, such as Figure 1 As shown, the second branch 5 is equipped with a second valve 3. One of the second valve 3 and the first valve 2 is a pressure regulating valve, and the other of the second valve 3 and the first valve 2 is a shut-off valve. It can be understood that when the demand of heat users changes, the pressure regulating valve can automatically respond to maintain the pressure stability of the coal-fired unit 100, ensuring the continuity and reliability of heating supply. This effectively prevents the impact of sudden changes in steam pressure on the heating network and user-end equipment. When the pressure regulating valve or other equipment needs maintenance, closing the shut-off valve can completely isolate the second branch 5 without shutting down the entire coal-fired unit 100, improving the convenience of maintenance.

[0032] In some embodiments of the present invention, the external heating unit 9 includes: a steam supply main network or a heating network heater; a first steam heater 6 and / or a second steam heater 7 connected to the steam supply main network; or, the first steam heater 6 and / or the second steam heater 7 connected to the heating network heater. It is understood that the first steam heater 6 may be connected to the steam supply main network, or the second steam heater 7 may be connected to the steam supply main network, or both the first steam heater 6 and the second steam heater 7 may be connected to the steam supply main network; alternatively, the first steam heater 6 may be connected to the heating network heater, or the second steam heater 7 may be connected to the heating network heater, or both the first steam heater 6 and the second steam heater 7 may be connected to the heating network heater. Therefore, by directly utilizing the existing steam supply network or heating network heaters, there is no need to construct a separate complex heating network for waste heat recovery, saving investment costs and space. Furthermore, the waste heat, as a supplementary heat source, is incorporated into the steam supply network or heating network heaters, which can enhance the overall heating capacity of the power plant and the flexibility of external heating regulation without increasing the load on the main boiler.

[0033] In some embodiments of the present invention, the control unit 10 is configured to adjust the steam flow rate of the steam boiler unit 1 based on the difference between the target air temperature and the real-time air temperature of the boiler assembly 8. For example, the control unit 10 issues a control command to the steam supply regulating valve of the steam boiler unit 1 (such as the regulating valve on the first branch 4) based on the calculated difference, changing the valve opening to increase or decrease the steam flow rate to the steam heater. An increase in steam flow rate increases heat exchange and raises the air temperature; a decrease in steam flow rate decreases heat exchange and lowers the air temperature.

[0034] In some embodiments of the present invention, the coal-fired unit 100 further includes a waste heat recovery unit 11, which is located between the external heating unit 9 and the boiler assembly 8. Both the primary air duct and the secondary air duct are connected to the collection header of the waste heat recovery unit 11. It is understood that after the steam used to heat the air completes its heat exchange, the condensate or incompletely condensed steam (i.e., waste heat carrier) generated will be discharged to the external heating unit 9 through their respective first and second heating branches via the collection header of the waste heat recovery unit 11.

[0035] The adjustment method of the coal-fired power unit 100 according to the second aspect embodiment of the present invention, applied to the coal-fired power unit 100 according to the first aspect embodiment of the present invention, includes: Step S1: Obtain the market electricity price A and the peak-shaving demand signal B of coal-fired unit 100 in real time; Step S2: Determine whether the market electricity price A is greater than the preset electricity price and whether the coal-fired unit 100 has a peak-shaving demand signal B. If the market electricity price A is greater than the preset electricity price, then execute step S1. If the market electricity price A is lower than the preset electricity price and the coal-fired unit 100 has a peak-shaving demand signal B, then execute step S3. Step S3: Start the steam boiler unit 1 and introduce steam into the first steam heater 6 and the second steam heater 7 to heat the combustion air to the preset temperature; Step S4: Maintain the combustion air at the preset temperature and reduce the turbine generator load to the target parameter value for deep peak shaving; Step S5: The steam passing through the first steam heater 6 and / or the second steam heater 7 is depressurized and introduced into the external heating unit 9. Step S6: When the peak shaving end signal is obtained or the market electricity price A is greater than the preset electricity price, shut down the steam boiler unit 1 and execute step S1.

[0036] Specifically, the preset electricity price is the critical economic electricity price calculated by combining the operation and maintenance costs of steam boiler unit 1 with the revenue from ancillary services for deep peak shaving.

[0037] Furthermore, step S3 also includes: acquiring and calculating the difference between the target air temperature and the real-time air temperature of the boiler assembly 8, and adjusting the output of the steam boiler unit 1 and the steam flow rate of the first branch 4.

[0038] According to the regulation method of the coal-fired unit 100 of the present invention, by calculating the deviation between the target air temperature and the real-time air temperature in real time, the actual demand of the control system for heat regulation is quantified, and a reliable feedback basis is provided; by actively reducing the load of the turbine generator unit while maintaining stable air temperature, the flexibility and regulation depth of the unit participating in the deep peak shaving of the power grid are improved.

[0039] The following will refer to Figure 1 and Figure 2 The operation of a coal-fired power unit 100 according to a specific embodiment of the present invention is described.

[0040] like Figure 1 and Figure 2 As shown, taking a 300MW coal-fired heating unit 100 as an example, the design output of steam boiler unit 1 is 20MW, and the outlet steam parameters are 1.3MPa and 300℃.

[0041] First, the control unit 10 acquires the market electricity price A and the peak-shaving demand signal B of the coal-fired unit 100 in real time. When it detects that the real-time electricity price has dropped to 0 yuan / MWh (below the preset threshold of 15 yuan / MWh) and at the same time receives a deep peak-shaving instruction to reduce the unit load to 90MW (30% of the rated load), the dual triggering conditions are met.

[0042] Next, the control unit 10 issues a command to start the steam boiler unit 1. The boiler quickly reaches full output within 2 minutes, generating steam with rated parameters. The first valve 2 opens, and the control unit 10 adjusts the second valve 3 to control the steam to enter the first steam heater 6 and the second steam heater 7. The steam exchanges heat with the cold air in the first steam heater 6 and the second steam heater 7. According to the set target air temperature (e.g., 90℃), the control unit 10 dynamically adjusts the output of the steam boiler unit 1 and the opening of the second valve 3 through closed-loop control, rapidly raising and stabilizing the primary and secondary air temperatures from the ambient temperature to around 90℃.

[0043] With the wind temperature reliably guaranteed, the control unit 10 coordinates the boiler assembly 8 and the turbine generator set to safely reduce the load to the target value of 90MW. Due to the significantly improved combustion conditions, the measured coal consumption under this condition is reduced by approximately 10-12g / kWh compared to the traditional method.

[0044] Then, the steam (pressure approximately 0.5 MPa, temperature approximately 160°C) after the duct heating is completed is collected from the outlet of the first steam heater 6 and the outlet of the second steam heater 7. The control unit 10 then activates the pressure reducing unit 12 to smoothly introduce this steam waste heat into the external heating unit 9 for industrial steam supply or heating, replacing part of the original extracted steam and realizing energy cascade utilization.

[0045] Next, during traditional deep peak shaving, low air temperature easily leads to the cold end wall temperature of the air preheater falling below the acid dew point, causing blockage. This invention uses a first steam heater 6 and a second steam heater 7 to raise the primary air inlet temperature and the secondary air inlet temperature entering the air preheater to above 90°C, directly increasing the cold end wall temperature of the air preheater and stabilizing it above the condensation temperature of ammonium bisulfate, thereby effectively alleviating the blockage problem of the air preheater.

[0046] Finally, when peak shaving ends or electricity prices rebound, control unit 10 performs an orderly shutdown: first, it closes pressure reducing unit 12 to stop waste heat recovery; then it adjusts second valve 3 and closes first valve 2 to stop supplying steam to first steam heater 6 and second steam heater 7; after the residual steam in the pipeline is drained, steam boiler unit 1 is shut down and coal-fired unit 100 is reset to standby.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A coal-fired power unit (100), characterized in that, include: A steam boiler unit (1) having a steam outlet; The distribution unit has a first valve (2), a first branch (4), and a second branch (5). The steam inlet of the first valve (2) is connected to the steam outlet. The first branch (4) is connected to the first outlet of the first valve (2). The second branch (5) is connected to the second outlet of the first valve (2). Boiler assembly (8) having a primary air duct and a secondary air duct, the primary air duct being connected to the first branch (4), the secondary air duct being connected to the second branch (5), a first steam heater (6) being provided in the primary air duct, and a second steam heater (7) being provided in the secondary air duct. An external heating unit (9) is connected to the first steam heater (6) and the second steam heater (7). The control unit (10) is electrically connected to the steam boiler unit (1), the distribution unit, the boiler assembly (8), and the external heating unit (9).

2. The coal-fired power unit (100) according to claim 1, characterized in that, The first steam heater (6) is connected to the external heating unit (9) via a first heating branch, and the second steam heater (7) is connected to the external heating unit (9) via a second heating branch. The control unit (10) is configured to acquire the market electricity price (A) and the peak demand signal (B) of the coal-fired unit (100) in real time, determine whether the market electricity price (A) is higher than a preset threshold, and control the on / off state of the first branch (4), and / or the second branch (5), and / or the first heating branch, and / or the second heating branch.

3. The coal-fired power unit (100) according to claim 2, characterized in that, The second branch (5) is provided with a second valve (3), one of the second valve (3) and the first valve (2) is a pressure regulating valve, and the other of the second valve (3) and the first valve (2) is a shut-off valve.

4. The coal-fired power unit (100) according to claim 2, characterized in that, The external heating unit (9) includes a steam supply network, and the first steam heater (6) and / or the second steam heater (7) are connected to the steam supply network.

5. The coal-fired power unit (100) according to claim 2, characterized in that, The external heating unit (9) includes: a heat network heater, and the first steam heater (6) and / or the second steam heater (7) are connected to the heat network heater.

6. The coal-fired power unit (100) according to claim 2, characterized in that, The control unit (10) is configured to adjust the steam supply flow rate of the steam boiler unit (1) based on the difference between the target air temperature and the real-time air temperature of the boiler assembly (8).

7. The coal-fired power unit (100) according to any one of claims 1-6, characterized in that, Also includes: Waste heat recovery unit (11) is located between external heating unit (9) and boiler assembly (8). The primary air duct and the secondary air duct are both connected to the collection header of the waste heat recovery unit (11).

8. A method for regulating a coal-fired power unit (100), characterized in that, Applied to any one of the coal-fired power units (100) according to claims 1-7, the adjustment method comprises: Step S1: Real-time acquisition of market electricity price (A) and peak-shaving demand signal (B) of the coal-fired unit (100); Step S2: Determine whether the market electricity price (A) is greater than the preset electricity price and whether the coal-fired power unit (100) has a peak-shaving demand signal (B). If the market electricity price (A) is greater than the preset electricity price, then execute step S1. If the market electricity price (A) is lower than the preset electricity price and the coal-fired power unit (100) has a peak-shaving demand signal (B), then execute step S3. Step S3: Start the steam boiler unit (1) and introduce steam into the first steam heater (6) and the second steam heater (7) to heat the combustion air to the preset temperature; Step S4: Maintain the combustion air at the preset temperature and reduce the turbine generator load to the target parameter value for deep peak shaving; Step S5: The steam passing through the first steam heater (6) and / or the second steam heater (7) is depressurized and introduced into the external heating unit (9); Step S6: When the peak shaving end signal is obtained or the market electricity price (A) is greater than the preset electricity price, shut down the steam boiler unit (1) and execute step S1.

9. The adjustment method for a coal-fired power unit (100) according to claim 8, characterized in that, The preset electricity price is the critical economic electricity price calculated by combining the operation and maintenance costs of the steam boiler unit (1) with the revenue from ancillary services for deep peak shaving.

10. The adjustment method for a coal-fired power unit (100) according to claim 8, characterized in that, Step S3 further includes: obtaining and calculating the difference between the target air temperature and the real-time air temperature of the boiler assembly (8), and adjusting the output of the steam boiler unit (1) and the steam flow rate of the first branch (4).

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