A coal-fired unit system for deep peak regulation and its operation method

Abstract

The present invention provides a coal-fired unit system for deep peak shaving and an operating method thereof, wherein the coal-fired unit system for deep peak shaving comprises: a thermal system of a coal-fired generator set, wherein the thermal system comprises a first steam drum, a superheater, a high-pressure cylinder of a steam turbine, an intermediate-pressure cylinder of a steam turbine, a low-pressure cylinder of a steam turbine, and a generator; a high-temperature solid-state heat storage system, wherein the high-temperature solid-state heat storage system comprises an interconnected solid heat storage device and an axial flow fan for extracting and storing high-temperature steam from the superheater, the high-pressure cylinder of the steam turbine, and the intermediate-pressure cylinder of the steam turbine, wherein the axial flow fan is used to perform heat exchange with the solid heat storage device; and a plurality of regulating valves and a plurality of sections of pipelines, wherein the regulating valves comprise a first extraction heat recovery regulating valve, a second extraction heat recovery regulating valve, and a third extraction heat recovery regulating valve. The present invention realizes flexible and efficient peak shaving of the coal-fired generator set, and improves the efficiency, economy, and environmental friendliness of the power generation system.

Description

Technical Field

[0001] The present invention relates to the technical field of peak-shaving operation of coal-fired power plants, and in particular to a coal-fired unit system for deep peak-shaving and an operation method thereof. Background Art

[0002] Amidst the growing pressures of global energy transition and climate change, coal-fired power generation, a key component of traditional energy, faces unprecedented challenges. While coal-fired power generation still accounts for a significant share of global electricity supply, its high emissions and energy consumption have drawn widespread attention. While the increasing share of renewable energy generation has alleviated these challenges, it has also created new ones, particularly by increasing the intensity and frequency of fluctuations in electricity demand. This has made the peak-shaving capabilities of traditional coal-fired power generation even more crucial.

[0003] Coal-fired units primarily implement autonomous peak-shaving through two methods: boiler combustion regulation and turbine load regulation to adapt to peak-shaving demands. Boiler combustion regulation dynamically adjusts the boiler's thermal power output by precisely controlling the ratio of fuel and air supply. For example, adjusting combustion parameters such as coal consumption, supply air volume, and induced draft volume effectively alters the heat generation rate during the combustion process, thereby affecting the steam flow rate supplied by the boiler to the turbine and, in turn, regulating the power output of the generator set. These operations require balancing combustion efficiency and emissions control to ensure stable unit operation under varying load conditions. Turbine load regulation primarily involves adjusting the opening of the regulating valve to control the flow of steam entering the turbine. This process involves precise control of steam flow, pressure, and temperature to ensure efficient and safe operation of the turbine under varying loads.

[0004] Currently, when coal-fired power generation units operate at low load, the boilers are unable to effectively regulate the supply of fuel and air. This inadequate regulation leads to low combustion efficiency, resulting in large amounts of underburned fuel and exhaust gas, which impacts overall system performance and stability. Furthermore, low-load operation reduces steam flow, lowering turbine efficiency and increasing energy consumption per unit of electricity. This not only results in economic losses but also exacerbates environmental pollution, hindering the achievement of sustainable development goals. Therefore, improving the peak-shaving capacity of coal-fired units under varying load conditions has become a pressing technical challenge. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a coal-fired unit system for deep peak regulation and an operation method thereof.

[0006] The present invention provides a coal-fired unit system for deep peak regulation, comprising: a thermal system of a coal-fired generator set, wherein the thermal system of the coal-fired generator set comprises a first steam drum, a superheater, a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine low-pressure cylinder and a generator, wherein one end of the superheater is connected to the first steam drum, and the other end is connected to the steam turbine high-pressure cylinder, the steam turbine high-pressure cylinder, the steam turbine intermediate-pressure cylinder and the steam turbine low-pressure cylinder are coaxially arranged and connected to the power grid through the generator; a high-temperature solid-state heat storage system, wherein the high-temperature solid-state heat storage system comprises a solid heat storage device and an axial flow fan that are interconnected, wherein the solid heat storage device is respectively connected to the superheater, the steam turbine high-pressure cylinder and the steam turbine intermediate-pressure cylinder through different pipelines and regulating valves, and is used to extract the superheater, the steam turbine high-pressure cylinder and the steam turbine intermediate-pressure cylinder. The high-temperature steam in the steam turbine pressure cylinder is stored, and the axial flow fan is used to exchange heat with the solid heat storage device; a plurality of regulating valves and a plurality of pipe sections, the regulating valves include a first extraction heat recovery regulating valve, a second extraction heat recovery regulating valve and a third extraction heat recovery regulating valve, and the pipes are used to respectively connect the various components in the thermal system of the coal-fired power generation unit and the various components in the high-temperature solid-state heat storage system, as well as to connect the thermal system of the coal-fired power generation unit and the high-temperature solid-state heat storage system; wherein, the first extraction heat recovery regulating valve is arranged between the high-pressure cylinder of the steam turbine and the high-pressure heater, and is used to adjust the extraction flow of the high-pressure cylinder of the steam turbine, and the second extraction heat recovery regulating valve is arranged between the intermediate-pressure cylinder of the steam turbine and the high-pressure heater, and is used to adjust the extraction flow of the intermediate-pressure cylinder of the steam turbine.

[0007] Optionally, the high-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet and an extraction outlet, the intermediate-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet, a first-stage extraction outlet and a second-stage extraction outlet, and the low-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet and an extraction outlet; wherein, the steam outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the intermediate-pressure cylinder of the steam turbine, and the steam outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the low-pressure cylinder of the steam turbine through a pipeline.

[0008] Optionally, the thermal system of the coal-fired power generation unit also includes: a high-pressure heater, the high-pressure heater including a steam inlet, a condensate working medium inlet and a condensate working medium outlet, the extraction steam outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater, and a first extraction steam reheat regulating valve is provided between the extraction steam outlet of the high-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater, the first-stage extraction steam outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater, and a second extraction steam reheat regulating valve is provided between the first-stage extraction steam outlet of the intermediate-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater, and the first extraction steam reheat regulating valve and the second extraction steam reheat regulating valve are used to adjust the extraction steam flow rate.

[0009] Optionally, the thermal system of the coal-fired power generation unit also includes a deaerator, which includes a steam inlet, a feed water medium inlet and a feed water medium outlet. The second-stage steam extraction outlet of the steam turbine intermediate pressure cylinder is connected to the steam inlet of the deaerator through a pipeline. A third steam extraction heat recovery regulating valve for adjusting the extraction flow is provided on the pipeline between the second-stage steam extraction outlet of the steam turbine intermediate pressure cylinder and the steam inlet of the deaerator.

[0010] Optionally, the thermal system of the coal-fired power generation unit also includes: a low-pressure heater, which includes a steam inlet, a condensate working medium inlet and a condensate working medium outlet, the steam extraction outlet of the low-pressure cylinder of the steam turbine is connected to the steam inlet of the low-pressure heater through a pipeline, and the condensate working medium outlet of the low-pressure heater is connected to the feed water working medium inlet of the deaerator.

[0011] Optionally, the thermal system of the coal-fired power generation unit also includes a condenser, a condensate pump, an economizer, a feed water pump and an air-water heat exchanger. The condenser includes a condensate working medium outlet, the steam outlet of the low-pressure cylinder of the steam turbine is connected to the condenser through a pipeline, the condensate working medium outlet of the condenser is connected to the condensate working medium inlet of the low-pressure heater through the condensate pump, the feed water working medium outlet of the deaerator is connected to the feed water working medium of the high-pressure heater through the feed water pump, and the economizer inlet is connected to the feed water working medium outlet of the high-pressure heater through the air-water heat exchanger.

[0012] Optionally, the regulating valve includes: a third regulating valve, a fourth regulating valve, a fifth regulating valve and a sixth regulating valve; wherein the third regulating valve is connected to the solid heat storage device and the superheater, and is used for transmitting high-temperature steam between the superheater and the solid heat storage device; the fourth regulating valve is connected to the solid heat storage device and the high-pressure cylinder of the steam turbine, and is used for transmitting high-temperature steam between the high-pressure cylinder of the steam turbine and the solid heat storage device; the fifth regulating valve is connected to the solid heat storage device and the Steam turbine intermediate pressure cylinder , used for high temperature steam in the steam turbine Medium pressure cylinder and the transmission between the solid heat storage device; the sixth regulating valve connects the solid heat storage device and the gas-water heat exchanger.

[0013] The present invention also provides an operating method for a coal-fired unit system for deep peak regulation, comprising the following steps: in the boiler startup stage: after the coal-fired boiler is ignited, combustion generates high-temperature steam, the generated high-temperature steam passes through the superheater, and then enters the turbine high-pressure cylinder, the turbine intermediate-pressure cylinder and the turbine low-pressure cylinder in turn to perform work, driving the generator to generate electricity, part of the high-temperature steam at the superheater outlet is extracted and introduced into a solid heat storage device, the heat storage device is continuously charged with heat, and the heat storage preparation is completed; in the boiler low-load operation stage: the first extraction heat recovery regulating valve and the second extraction heat recovery regulating valve are closed, allowing the extraction working medium to flow back from the deaerator and the high-pressure heater to the turbine high-pressure cylinder and the turbine intermediate-pressure cylinder to perform work; in the boiler high-load operation stage: the heat in the solid-state heat storage device is exchanged with the air through an axial flow fan, and the feed water is heated through an air-water heat exchanger to enter the economizer.

[0014] Optionally, the operating method further includes the step of: opening the fourth regulating valve and the fifth regulating valve during the low-load operation stage of the boiler to recover part of the heat of the working fluid to the solid-state heat storage device.

[0015] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0016] This invention provides a coal-fired unit system and operating method for deep peak shaving. By extracting steam for heat recovery, the system reduces unit load while maintaining a certain steam flow rate, thereby improving turbine power generation efficiency. Furthermore, high-temperature solid-state thermal storage technology is employed to extract some steam and store heat in a solid-state thermal storage material. This heat is released when the unit load increases, further improving turbine efficiency and the unit's peak shaving capability. This system not only enhances the unit's adaptability under varying loads, but also effectively reduces the unit cost of electricity, improving the economic efficiency of power generation, and offering favorable environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the drawings without creative work.

[0018] Figure 1 This is a schematic structural diagram of a coal-fired unit system for deep peak regulation according to an embodiment of the present disclosure;

[0019] In the figure: 1 is the first steam drum, 2 is the superheater, 3 is the economizer, 4 is the air preheater, 5 is the water-cooled wall and its lower water tank, 6 is the high-pressure cylinder of the steam turbine, 7 is the intermediate-pressure cylinder of the steam turbine, 8 is the low-pressure cylinder of the steam turbine, 9 is the generator, 10 is the condenser, 11 is the air-drying tower, 12 is the circulating water pump, 13 is the condensate pump, 14 is the low-pressure heater, 15 is the deaerator, 16 is the feed water pump, 17 is the high-pressure heater, 18 is the air-water heat exchanger, 19 is the axial flow fan, 20 is the solid heat storage device, 21 is the chimney, 22 is the fan, 24 is the third regulating valve, 27 is the electric heating control device, 28 is the fifth regulating valve, 29 is the fourth regulating valve, 30 is the first extraction steam heat recovery regulating valve, 31 is the second extraction steam heat recovery regulating valve, 32 is the third extraction steam heat recovery regulating valve, 33 is the sixth regulating valve, and 35 is the second steam drum. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0021] In the present invention, unless otherwise specified, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of a device in normal use, and "inner" and "outer" refer to positions relative to the device's outline. Furthermore, the terms "first, second, and third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features defined as "first, second, and third" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise explicitly and specifically defined.

[0022] At present, when traditional coal-fired units are under low load conditions, the boilers are unable to effectively regulate the supply of fuel and air, which may affect the performance and stability of the overall system. During peak load regulation, the system operation is restricted by the boiler's stable combustion load, which limits the unit's peak load regulation capability. Moreover, the decrease in steam flow under low load conditions leads to a decrease in turbine efficiency and an increase in energy consumption.

[0023] Therefore, the present invention provides a coal-fired unit system for deep peak regulation and an operation method thereof, which can effectively address the peak regulation problem of coal-fired power generation units and realize flexible and efficient peak regulation of coal-fired power generation units.

[0024] The present invention provides a coal-fired unit system for deep peak regulation, comprising: a thermal system of a coal-fired generator set, wherein the thermal system of the coal-fired generator set comprises a first steam drum, a superheater, a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine low-pressure cylinder and a generator, wherein one end of the superheater is connected to the first steam drum, and the other end is connected to the steam turbine high-pressure cylinder, the steam turbine high-pressure cylinder, the steam turbine intermediate-pressure cylinder and the steam turbine low-pressure cylinder are coaxially arranged and connected to the power grid through the generator; a high-temperature solid-state heat storage system, wherein the high-temperature solid-state heat storage system comprises a solid heat storage device and an axial flow fan that are interconnected, wherein the solid heat storage device is respectively connected to the superheater, the steam turbine high-pressure cylinder and the steam turbine intermediate-pressure cylinder through different pipelines and regulating valves, and is used to extract the superheater, the steam turbine high-pressure cylinder and the steam turbine intermediate-pressure cylinder. The high-temperature steam in the steam turbine pressure cylinder is stored, and the axial flow fan is used to exchange heat with the solid heat storage device; a plurality of regulating valves and a plurality of pipe sections, the regulating valves include a first extraction heat recovery regulating valve, a second extraction heat recovery regulating valve and a third extraction heat recovery regulating valve, and the pipes are used to respectively connect the various components in the thermal system of the coal-fired power generation unit and the various components in the high-temperature solid-state heat storage system, as well as to connect the thermal system of the coal-fired power generation unit and the high-temperature solid-state heat storage system; wherein, the first extraction heat recovery regulating valve is arranged between the high-pressure cylinder of the steam turbine and the high-pressure heater, and is used to adjust the extraction flow of the high-pressure cylinder of the steam turbine, and the second extraction heat recovery regulating valve is arranged between the intermediate-pressure cylinder of the steam turbine and the high-pressure heater, and is used to adjust the extraction flow of the intermediate-pressure cylinder of the steam turbine.

[0025] Figure 1 A coal-fired unit system for deep peak regulation according to an embodiment of the present disclosure is shown, and a specific example of the present invention is further described in detail below with reference to the accompanying drawings.

[0026] Reference Figure 1 The embodiment of the present disclosure provides a coal-fired unit system for deep peak regulation, including a thermal system of a coal-fired power generation unit, a high-temperature solid-state heat storage system, a plurality of regulating valves and a plurality of pipeline sections.

[0027] Specifically, the thermal system of the coal-fired power generation unit includes a first steam drum 1 for supplying and storing steam, a superheater 2, an economizer 3 and an air preheater 4, which are respectively used to heat steam, preheat feed water and preheat air; a water-cooled wall and its lower water box 5, a turbine high-pressure cylinder 6, a turbine intermediate-pressure cylinder 7 and a turbine low-pressure cylinder 8, the turbine high-pressure cylinder 6, the turbine intermediate-pressure cylinder 7 and the turbine low-pressure cylinder 8 are used to convert steam energy into mechanical energy, and a generator 9 driven by the turbine to generate electricity; the thermal system of the coal-fired power generation unit also includes: a condenser 10, a drying tower 11, a circulating water pump 12, a condensate pump 13, and a low-pressure heater 14, which are used to cool and circulate steam condensate; a deaerator 15, which is used to remove oxygen in feed water to prevent system corrosion; a feed water pump 16 and a high-pressure heater 17, which are used to pressurize and heat feed water; and an air-water heat exchanger 18 for heat exchange and cooling.

[0028] Among them, the turbine high-pressure cylinder 6 includes a steam inlet, a steam outlet and an extraction outlet, the turbine intermediate-pressure cylinder 7 includes a steam inlet, a steam outlet, a first-stage extraction outlet and a second-stage extraction outlet, and the turbine low-pressure cylinder 8 includes a steam inlet, a steam outlet and an extraction outlet; the steam outlet of the turbine high-pressure cylinder is connected to the steam inlet of the turbine intermediate-pressure cylinder, and the steam outlet of the turbine intermediate-pressure cylinder is connected to the steam inlet of the turbine low-pressure cylinder through a pipeline.

[0029] like Figure 1 As shown, one end of the superheater 2 is connected to the first steam drum 1, and the other end is connected to the steam inlet of the turbine high-pressure cylinder 6 through a pipeline, that is, the outlet of the superheater 2 is connected to the steam inlet of the turbine high-pressure cylinder 6. The turbine high-pressure cylinder 6, the turbine intermediate-pressure cylinder 7 and the turbine low-pressure cylinder 8 are coaxial and connected to the power grid through the generator 9.

[0030] In the disclosed embodiment, the high-pressure heater 17 includes a steam inlet, a condensate working medium inlet, and a condensate working medium outlet. The extraction steam outlet of the steam turbine high-pressure cylinder 6 is connected to the steam inlet of the high-pressure heater 17 via a pipeline. A first extraction steam reheat regulating valve 30 is provided between the extraction steam outlet of the steam turbine high-pressure cylinder 6 and the steam inlet of the high-pressure heater 17. The first extraction steam reheat regulating valve 30 is used to regulate the extraction steam flow rate. The first-stage extraction steam outlet of the steam turbine intermediate-pressure cylinder 7 is connected to the steam inlet of the high-pressure heater 17 via a pipeline. A second extraction steam reheat regulating valve 31 is provided on the pipeline between the first-stage extraction steam outlet of the steam turbine intermediate-pressure cylinder 7 and the steam inlet of the high-pressure heater 17. The second extraction steam reheat regulating valve 31 is used to regulate the extraction steam flow rate.

[0031] like Figure 1As shown, the deaerator 15 includes a steam inlet, a feedwater medium inlet, and a feedwater medium outlet. The second-stage extraction steam outlet of the steam turbine intermediate pressure cylinder 7 is connected to the steam inlet of the deaerator 15 via a pipeline. A third extraction steam reheat regulating valve 32 for regulating the extraction steam flow is installed on the pipeline between the second-stage extraction steam outlet of the steam turbine intermediate pressure cylinder 7 and the steam inlet of the deaerator 15. The low-pressure heater 14 includes a steam inlet, a condensate medium inlet, and a condensate medium outlet. The extraction steam outlet of the steam turbine low-pressure cylinder 8 is connected to the steam inlet of the low-pressure heater 14 via a pipeline, and the condensate medium outlet of the low-pressure heater 14 is connected to the feedwater medium inlet of the deaerator 15.

[0032] The thermal system of the coal-fired power generation unit also includes a condenser 10, a condensate pump 13, an economizer 3, a feedwater pump 16, and an air-water heat exchanger 18. The condenser 10 includes a condensate outlet, the steam outlet of the low-pressure cylinder 8 of the steam turbine is connected to the condenser 10 via a pipeline, the condensate outlet of the condenser 10 is connected to the condensate inlet of the low-pressure heater 14 via the condensate pump 13, the feedwater outlet of the deaerator 15 is connected to the feedwater of the high-pressure heater 17 via the feedwater pump 16, and the inlet of the economizer 3 is connected to the feedwater outlet of the high-pressure heater 17 via the air-water heat exchanger 18.

[0033] In the embodiment of the present disclosure, the high-temperature solid-state heat storage system includes a solid heat storage device 20 and an axial flow fan 19 that are interconnected. The solid heat storage device 20 is connected to the superheater 2 through a third regulating valve 24 and a pipeline, and is used to extract and store high-temperature steam from the outlet of the superheater 2; the solid heat storage device 20 is connected to the high-pressure cylinder 6 of the turbine through a fourth regulating valve 29 and a pipeline, and is used to extract and store high-temperature steam; the solid heat storage device 20 is connected to the intermediate-pressure cylinder 7 of the turbine through a fifth regulating valve 28 and a pipeline, and is used to extract and store medium and high-temperature steam.

[0034] After the solid heat storage device 20 completes heat storage, it exchanges heat with the axial flow fan 19. The hot air after the heat exchange exchanges heat with the air-water heat exchanger 18 to heat the feed water and then send it to the economizer 3.

[0035] When a coal-fired unit is operating in peak-shaving mode, it primarily implements autonomous peak-shaving through two methods: boiler combustion regulation and turbine load regulation. Boiler combustion regulation is one of the primary means of achieving flexible peak-shaving power generation from coal-fired units. Its fundamental principle is to control the boiler's heat output and steam generation by adjusting the fuel and air supply within the boiler. In practice, precise control of the coal feeding system allows dynamic adjustment of fuel supply to accommodate fluctuations in grid load. Simultaneously, fan operation is adjusted to alter air flow, optimize combustion efficiency, and ensure efficient combustion under varying boiler loads. This multi-dimensional regulation approach enables the boiler to quickly respond to fluctuations in grid demand, fully leveraging its peak-shaving capabilities. Compared to boiler regulation, turbine load regulation focuses on varying generator output power by adjusting steam flow and pressure. Specifically, turbine regulation relies primarily on precise control of the inlet and exhaust valves. Adjusting the valve opening directly affects the steam inflow, thereby adjusting the turbine's power generation capacity. To meet the dynamic load demands of the power grid, steam turbine systems are typically equipped with real-time monitoring and automatic adjustment capabilities, enabling rapid load tracking when power demand fluctuates. This highly accurate and stable steam turbine load adjustment mechanism allows coal-fired units to smoothly transition between baseload and peak load, optimizing the overall operational efficiency of the power grid.

[0036] The present invention also provides an operating method for a coal-fired unit system for deep peak regulation, comprising the following steps: in the boiler startup stage: after the coal-fired boiler is ignited, combustion generates high-temperature steam, the generated high-temperature steam passes through the superheater, and then enters the turbine high-pressure cylinder, the turbine intermediate-pressure cylinder and the turbine low-pressure cylinder in turn to perform work, driving the generator to generate electricity, part of the high-temperature steam at the superheater outlet is extracted and introduced into a solid heat storage device, the heat storage device is continuously charged with heat, and the heat storage preparation is completed; in the boiler low-load operation stage: the first extraction heat recovery regulating valve and the second extraction heat recovery regulating valve are closed, allowing the extraction working medium to flow back from the deaerator and the high-pressure heater to the turbine high-pressure cylinder and the turbine intermediate-pressure cylinder to perform work; in the boiler high-load operation stage: the heat in the solid-state heat storage device is exchanged with the air through an axial flow fan, and the feed water is heated through an air-water heat exchanger to enter the economizer.

[0037] Taking the normal operation of the coal-fired unit as an example, in the embodiment of the present disclosure, when the coal-fired unit system for deep peak regulation is running, the path of the thermal cycle of the power generation cycle medium is as follows: Figure 1Specifically, after the coal-fired boiler is ignited, combustion produces high-temperature steam. The generated steam is further heated by the economizer 3, water-cooled wall 5, and superheater 2 before entering the high-pressure cylinder 6 of the steam turbine. The main steam then enters the high-pressure cylinder 6, the intermediate-pressure cylinder 7, and the low-pressure cylinder 8 of the steam turbine, where it expands and generates power. Simultaneously, some steam is extracted from the high-pressure cylinder 6 and the intermediate-pressure cylinder 7 to heat the feedwater, reducing the amount of steam used for turbine work and completing the power generation cycle under normal operating conditions. The main steam expands step by step in the steam turbine, performing work in the high-pressure cylinder 6, the intermediate-pressure cylinder 7, and the low-pressure cylinder 8. The exhaust steam at the outlet of the low-pressure cylinder 8 is condensed through a cooling water circuit consisting of a condenser 10, a cooling tower 11, and a circulating water pump 12, becoming condensed water. This condensed water is then transported by a condensate pump 13 to a low-pressure heater 14 for preliminary heating before entering a deaerator 15 for deoxidation, producing low-pressure condensed water. Afterwards, it enters the feed water pump 16, the high-pressure heater 17 and the air-water heat exchanger 18 in sequence, and finally the high-pressure feed water enters the boiler for recycling after further heating.

[0038] In some embodiments, during the low-load operation stage of the boiler, the fourth regulating valve and the fifth regulating valve may be opened to recover part of the heat of the working fluid to the solid-state heat storage device.

[0039] Specifically, in the embodiment disclosed herein, when the coal-fired power generation unit is operating in a deep peak-shaving state, the boiler operates at low load, and the steam flow rate decreases, resulting in a significant decrease in the operating efficiency of the turbine high-pressure cylinder 6 and the turbine intermediate-pressure cylinder 7. Under the low load of the coal-fired power generation unit, the turbine high-pressure cylinder 6 and the turbine intermediate-pressure cylinder 7 are used to extract steam for heat recovery, and the first extraction heat recovery regulating valve 30 and the second extraction heat recovery regulating valve 31 are closed, so that the extraction steam working medium that heats the feed water in the deaerator 15 and the high-pressure heater 17 flows back to the turbine high-pressure cylinder 6 and the turbine intermediate-pressure cylinder 7 to perform work, thereby increasing the flow rate of the working medium circulating in the turbine high-pressure cylinder 6 and the turbine intermediate-pressure cylinder 7, and improving the operating efficiency of the turbine high-pressure cylinder 6 and the turbine intermediate-pressure cylinder 7; at the same time, the fourth regulating valve 28 and the fifth regulating valve 29 are opened according to the peak-shaving depth to recover part of the heat of the working medium and recover it to the solid heat storage device 20. The steam obtained by heat exchange and water vapor separation in the fluid entering the second steam drum 35 is reintroduced into the economizer 3, and then merged into the first steam drum 1 for a new round of thermal cycle. If it is water, it is introduced into the gas-water heat exchanger 18 through the sixth regulating valve 33, and then introduced into the economizer 3 after heat exchange, and finally merged into the first steam drum 1 to achieve low-load operation.

[0040] In some embodiments, the solid heat storage device absorbs and stores thermal energy through a solid medium. Preferably, the solid medium may be ceramic or a special refractory material.

[0041] When the required power generation load increases, cold air is introduced through the axial fan 19 and undergoes convection heat exchange with the high-temperature solid thermal storage material in the solid thermal storage device 20, releasing the stored heat into the air, ultimately heating it into high-temperature hot air. The high-temperature hot air further heats the feed water from the high-pressure heater 17, thereby heating it into steam. After heat exchange, the high-temperature hot air is cooled and further utilized. It is introduced into the induced draft fan 22 as the heat source for the air preheater 4, where the hot air is mixed with the pulverized coal for preheating. This indirectly increases the boiler load, improves the steam flow rate, and improves the power generation efficiency and power generation load of the steam turbine unit.

[0042] This system combines traditional coal-fired generators with a high-temperature solid-state thermal storage system. The solid-state thermal storage device stores and releases thermal energy, achieving more efficient energy utilization and heat recovery. This not only alleviates peak load pressure but also improves overall energy efficiency. Through the interaction of flexible steam extraction and solid-state thermal storage, this coal-fired unit system for deep peak shaving achieves greater thermal flexibility and energy utilization, thereby achieving the goal of energy conservation and emission reduction.

[0043] In the embodiment disclosed herein, the heat source of the solid-state heat storage device 20 is divided into three parts: the high-temperature steam extracted from the outlet of the superheater 2 through the third regulating valve 24 and the pipeline is heat exchanged with the high-temperature solid-state heat storage device 20; the high-temperature steam extracted from the high-pressure cylinder 6 of the steam turbine through the fourth regulating valve 29 and the pipeline is heat exchanged with the solid heat storage device 20; and the high-temperature steam discharged from the intermediate-pressure cylinder 7 of the steam turbine through the fifth regulating valve 28 and the pipeline is heat exchanged with the solid heat storage device 20.

[0044] In some embodiments, when the unit is operating in peak load regulation mode, dynamic control of the boiler's thermal power output can be achieved through boiler combustion regulation. For example, this involves adjusting combustion parameters such as the coal consumption, air supply, and induced draft. This reduces the boiler load, thereby reducing the steam flow at the turbine inlet, thereby regulating the power output of the generator set. Specifically, in the first embodiment of the present disclosure, the reduction in boiler load causes a decrease in the steam parameters at the turbine inlet. At this point, the first extraction heat regeneration regulating valve 30, the second extraction heat regeneration regulating valve 31, and the third heat regeneration regulating valve 32 are closed, thereby increasing the steam flow to the turbine. The increased electrical load due to the recirculated steam can be heated by the electric heating control device 27 to recover heat from the solid thermal storage device 20.

[0045] In other embodiments, when the unit is in peak-shaving operation, the steam flow of the turbine high-pressure cylinder, the turbine intermediate-pressure cylinder, and the turbine low-pressure cylinder can be flexibly reduced according to the peak-shaving depth requirement to reduce the power generation load. Specifically, in the second embodiment of the present disclosure, the turbine load is adjusted by adjusting the opening of the third regulating valve 24, the fifth regulating valve 28, and the fourth regulating valve 29 to control the flow of steam entering the turbine. At this time, five steam extraction methods can be selected, including extracting the main steam from the third regulating valve 24, extracting part of the steam after the work of the turbine high-pressure cylinder 6, extracting all the steam after the work of the turbine high-pressure cylinder 6, extracting part of the steam after the work of the turbine intermediate-pressure cylinder 7, and extracting all the steam after the work of the turbine intermediate-pressure cylinder 7. The steam is introduced into the solid heat storage device 20 to heat the heat storage body, thereby achieving different degrees of peak-shaving state.

[0046] In the third embodiment of the present disclosure, during energy release, cold air is introduced through an axial flow fan 19, which then undergoes convective heat exchange with the high-temperature solid thermal storage material in the solid thermal storage device 20, ultimately heating it to high-temperature hot air. This hot air then further heats the feedwater from the high-pressure heater, converting it into steam. The hot air, after heat exchange, is cooled and further utilized by the fan 22 as a heat source for the air preheater 4, where the hot air is mixed with the pulverized coal for preheating. This indirectly increases the boiler load, improves the steam flow rate, and improves the power generation efficiency and power generation load of the steam turbine unit.

[0047] The coal-fired unit system and operating method provided by the present invention for deep peak shaving effectively improves the operating efficiency of the steam turbine by introducing steam extraction and heat recovery technology to maintain steam flow when the coal-fired unit load decreases, thereby achieving efficient operation of the coal-fired unit under low-load conditions and reducing reliance on the boiler's stable combustion load. At the same time, the system utilizes high-temperature solid-state thermal storage technology to store heat from steam or flue gas extracted during the operation of the coal-fired unit in high-temperature solid-state thermal storage materials. These materials can maintain thermal energy for long periods of time at high temperatures and quickly release it during peak loads, providing additional thermal energy support, further enhancing the unit's peak shaving capability and overall energy utilization efficiency.

[0048] The present invention provides a coal-fired unit system for deep peak regulation. When the boiler is operating at low load, the steam flow rate of the steam turbine inlet is increased by extracting and recovering steam, thereby improving the power generation efficiency of the steam turbine. At the same time, when the boiler is operating at low load to ensure safe and stable operation, the coal-fired unit system for deep peak regulation of the present invention can achieve lower load operation of the thermal system of the coal-fired generator set through coordinated control of pipeline valves, recover excess steam energy through the high-temperature solid-state heat storage system, and use this energy for peak regulation or electricity consumption according to demand. The present invention couples high-temperature solid thermal storage technology, and can perform peak regulation of the coal-fired generator set alone or coupled peak regulation of the two, thereby improving the peak regulation depth and flexibility of the coal-fired unit.

[0049] The operating method for a coal-fired unit system for deep peak shaving, provided by this invention, combines optimized structural design with precise steam extraction and operating strategies to form a flexible peak-shaving solution. This solution not only improves the adaptability of coal-fired units under varying loads, but also effectively reduces the production cost per unit of electricity, improving the economic efficiency of power generation. Through more efficient combustion and energy conversion processes, the system also significantly reduces greenhouse gas emissions, providing significant environmental benefits.

[0050] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A coal-fired unit system for deep peak regulation, characterized in that: include: A thermal system of a coal-fired power generation unit, comprising a first steam drum, a superheater, a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine low-pressure cylinder, and a generator, wherein one end of the superheater is connected to the first steam drum and the other end is connected to the steam turbine high-pressure cylinder; the steam turbine high-pressure cylinder, steam turbine intermediate-pressure cylinder, and steam turbine low-pressure cylinder are coaxially arranged and connected to a power grid via the generator; A high-temperature solid-state thermal storage system, comprising a solid thermal storage device and an axial flow fan connected to each other, wherein the solid thermal storage device is respectively connected to the superheater, the high-pressure cylinder of the steam turbine, and the intermediate-pressure cylinder of the steam turbine through different pipes and regulating valves, and is used to extract and store high-temperature steam in the superheater, the high-pressure cylinder of the steam turbine, and the intermediate-pressure cylinder of the steam turbine, and the axial flow fan is used to exchange heat with the solid thermal storage device; Several regulating valves and several sections of pipelines, wherein the regulating valves include a first extraction steam heat recovery regulating valve, a second extraction steam heat recovery regulating valve, and a third extraction steam heat recovery regulating valve, and the pipelines are used to respectively connect the components of the thermal system of the coal-fired power generation unit and the components of the high-temperature solid-state thermal storage system, and to connect the thermal system of the coal-fired power generation unit and the high-temperature solid-state thermal storage system; wherein, The first steam extraction heat recovery regulating valve is arranged between the high-pressure cylinder of the steam turbine and the high-pressure heater, and is used to adjust the steam extraction flow of the high-pressure cylinder of the steam turbine. The second steam extraction heat recovery regulating valve is arranged between the intermediate-pressure cylinder of the steam turbine and the high-pressure heater, and is used to adjust the steam extraction flow of the intermediate-pressure cylinder of the steam turbine.

2. The coal-fired unit system for deep peak regulation according to claim 1, characterized in that: The high-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet and an extraction outlet; the intermediate-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet, a first-stage extraction outlet and a second-stage extraction outlet; the low-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet and an extraction outlet; wherein, The steam outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the intermediate-pressure cylinder of the steam turbine, and the steam outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the low-pressure cylinder of the steam turbine through a pipeline.

3. The coal-fired unit system for deep peak regulation according to claim 2, characterized in that: The thermal system of the coal-fired power generation unit also includes: a high-pressure heater, which includes a steam inlet, a condensate working medium inlet and a condensate working medium outlet. The extraction steam outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater. A first extraction steam reheat regulating valve is provided between the extraction steam outlet of the high-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater. The first-stage extraction steam outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater. A second extraction steam reheat regulating valve is provided between the first-stage extraction steam outlet of the intermediate-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater. The first extraction steam reheat regulating valve and the second extraction steam reheat regulating valve are used to adjust the extraction steam flow rate.

4. The coal-fired unit system for deep peak regulation according to claim 3, characterized in that: The thermal system of the coal-fired power generation unit also includes a deaerator, which includes a steam inlet, a feed water medium inlet and a feed water medium outlet. The second-stage steam extraction outlet of the steam turbine intermediate pressure cylinder is connected to the steam inlet of the deaerator through a pipeline. A third steam extraction heat recovery regulating valve for adjusting the extraction flow is provided on the pipeline between the second-stage steam extraction outlet of the steam turbine intermediate pressure cylinder and the steam inlet of the deaerator.

5. The coal-fired unit system for deep peak regulation according to claim 4, characterized in that: The thermal system of the coal-fired power generation unit also includes: a low-pressure heater, which includes a steam inlet, a condensate working medium inlet and a condensate working medium outlet. The steam extraction outlet of the low-pressure cylinder of the steam turbine is connected to the steam inlet of the low-pressure heater through a pipeline, and the condensate working medium outlet of the low-pressure heater is connected to the feed water working medium inlet of the deaerator.

6. The coal-fired unit system for deep peak regulation according to claim 5, characterized in that: The thermal system of the coal-fired power generation unit also includes a condenser, a condensate pump, an economizer, a feed water pump and an air-water heat exchanger. The condenser includes a condensate working medium outlet. The steam outlet of the low-pressure cylinder of the steam turbine is connected to the condenser through a pipeline. The condensate working medium outlet of the condenser is connected to the condensate working medium inlet of the low-pressure heater through the condensate pump. The feed water working medium outlet of the deaerator is connected to the feed water working medium of the high-pressure heater through the feed water pump. The economizer inlet is connected to the feed water working medium outlet of the high-pressure heater through the air-water heat exchanger.

7. The coal-fired unit system for deep peak regulation according to claim 6, characterized in that: The regulating valves include: a third regulating valve, a fourth regulating valve, a fifth regulating valve and a sixth regulating valve; wherein, The third regulating valve connects the solid heat storage device and the superheater, and is used for transmitting high-temperature steam between the superheater and the solid heat storage device; The fourth regulating valve connects the solid heat storage device and the high-pressure cylinder of the steam turbine, and is used for transmitting high-temperature steam between the high-pressure cylinder of the steam turbine and the solid heat storage device; the fifth regulating valve connects the solid heat storage device and the intermediate-pressure cylinder of the steam turbine, and is used for transmitting high-temperature steam between the intermediate-pressure cylinder of the steam turbine and the solid heat storage device; The sixth regulating valve connects the solid heat storage device and the gas-water heat exchanger.

8. An operating method for a coal-fired unit system for deep peak regulation according to any one of claims 1 to 7, characterized in that: Including steps: During the boiler startup phase: After the coal-fired boiler is ignited, combustion generates high-temperature steam. The generated high-temperature steam passes through the superheater and then sequentially enters the high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder of the steam turbine to perform work, driving the generator to generate electricity. Part of the high-temperature steam at the superheater outlet is extracted and introduced into the solid heat storage device, which is continuously charged to complete the heat storage preparation; During the low-load operation phase of the boiler: close the first extraction steam reheat regulating valve and the second extraction steam reheat regulating valve to allow the extraction steam to flow back from the deaerator and high-pressure heater to the turbine high-pressure cylinder and turbine intermediate-pressure cylinder to perform work; During the high-load operation stage of the boiler: the heat in the solid-state heat storage device is exchanged with the air through the axial flow fan, and the feed water is heated through the air-water heat exchanger and enters the economizer.

9. The method for operating a coal-fired unit system for deep peak regulation according to claim 8, characterized in that: The method further includes the following steps: during the low-load operation stage of the boiler, opening the fourth regulating valve and the fifth regulating valve to recover part of the heat of the working fluid to the solid-state heat storage device.

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