Coal-fired unit system for deep peak regulation and operation method of coal-fired unit system

Abstract

The invention provides a coal-fired unit system for deep peak regulation and an operation method thereof, the coal-fired unit system for deep peak regulation comprises a coal-fired unit thermodynamic system, the coal-fired unit thermodynamic system comprises a first steam pocket, a superheater, a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine low-pressure cylinder and a generator; the high-temperature solid heat storage system comprises a solid heat storage device and an axial flow fan which are connected with each other and is used for extracting and storing high-temperature steam in the superheater, the steam turbine high-pressure cylinder and the steam turbine intermediate-pressure cylinder, and the axial flow fan is used for exchanging heat with the solid heat storage device; the adjusting valves comprise a first steam extraction and heat regeneration adjusting valve, a second steam extraction and heat regeneration adjusting valve and a third steam extraction and heat regeneration adjusting valve. According to the invention, flexible and efficient peak regulation of the coal-fired power generation unit is realized, and the efficiency, economy and environmental friendliness of the power generation system are improved.

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] Against the backdrop of increasing pressure from global energy transition and climate change, coal-fired power generation units, as an important part of traditional energy, are facing unprecedented challenges. Coal-fired power generation still accounts for a large share of global electricity supply, but its high emissions and high energy consumption have attracted widespread attention. The gradual increase in the share of renewable energy power generation has alleviated this problem while also bringing new problems, especially making electricity demand fluctuate more violently and frequently. The peak-shaving capacity of traditional coal-fired units is particularly important.

[0003] The self-peaking regulation of coal-fired units is mainly achieved through two means, namely, boiler combustion regulation and turbine load regulation to meet the peaking demand. Among them, boiler combustion regulation is to achieve dynamic regulation of boiler thermal power output by accurately controlling the ratio of fuel supply and air supply. For example, adjusting combustion parameters such as coal consumption, air supply and induced draft can effectively change the heat generation rate during the combustion process, thereby affecting the steam flow provided by the boiler to the turbine, and then regulating the power output of the generator set. Such operations need to balance combustion efficiency and emission control to ensure stable operation of the unit under different load conditions. The regulation of turbine load is mainly achieved by 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 the operating efficiency and safety of the turbine under different loads.

[0004] At present, when coal-fired power generation units are operating under low load conditions, the boiler cannot effectively regulate the supply of fuel and air. This lack of regulation leads to low combustion efficiency, produces a large amount of incompletely burned fuel and exhaust gas, and affects the performance and stability of the overall system. At the same time, low-load operation also leads to a decrease in steam flow, thereby reducing the power generation efficiency of the steam turbine and increasing the energy consumption per unit of electricity. This not only causes economic losses, but also aggravates environmental pollution and affects the realization of sustainable development goals. Therefore, how to improve the peak-shaving capacity of coal-fired units under different load conditions has become a technical problem that needs to be solved urgently. 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 medium-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 medium-pressure cylinder and the steam turbine low-pressure cylinder are coaxially arranged and connected to a 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 connected to each other, wherein the solid heat storage device is respectively connected to the superheater, the steam turbine high-pressure cylinder and the steam turbine medium-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 medium-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 components in the thermal system of the coal-fired generator set, the components in the high-temperature solid-state heat storage system, and connect the thermal system of the coal-fired generator set 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 a steam extraction outlet, the intermediate-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet, a first-stage steam extraction outlet and a second-stage steam extraction outlet, and the low-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet and a steam 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 steam extraction outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater, a first steam extraction heat recovery regulating valve is provided between the steam extraction outlet of the high-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater, the first-stage steam extraction outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater, a second steam extraction heat recovery regulating valve is provided between the first-stage steam extraction outlet of the intermediate-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater, the first steam extraction heat recovery regulating valve and the second steam extraction heat recovery 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, and a third steam extraction heat recovery regulating valve for adjusting the extraction flow rate 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 medium outlet, the steam outlet of the low-pressure cylinder of the steam turbine is connected to the condenser through a pipeline, the condensate medium outlet of the condenser is connected to the condensate medium inlet of the low-pressure heater through the condensate pump, the feed water medium outlet of the deaerator is connected to the feed water medium of the high-pressure heater through the feed water pump, and the economizer inlet is connected to the feed water 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 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 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 a superheater, and then sequentially enters the high-pressure cylinder of a steam turbine, the intermediate-pressure cylinder of a steam turbine, and the low-pressure cylinder of a steam turbine to perform work, driving the generator to generate electricity, part of the high-temperature steam at the outlet of the superheater is extracted and introduced into a solid heat storage device, the heat storage device is continuously charged with heat, and heat storage preparation is completed; in the boiler low-load operation stage: the first steam extraction heat recovery regulating valve and the second steam 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 high-pressure cylinder of the steam turbine and the intermediate-pressure cylinder of the steam turbine 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: 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.

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

[0016] The present invention provides a coal-fired unit system for deep peak regulation and its operation method, which reduces the unit load while ensuring a certain steam flow rate by extracting steam and recovering heat, thereby improving the power generation efficiency of the steam turbine. At the same time, high-temperature solid-state heat storage technology is adopted to extract part of the steam to store heat in the solid-state heat storage material, and release heat energy when the unit load increases, thereby further improving the efficiency of the steam turbine and the peak regulation capacity of the unit. The system not only improves the adaptability of the unit under different loads, but also effectively reduces the production cost of unit electricity, improves the economy of power generation, and has good 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 drawings required for use in the description of the embodiments will be briefly introduced below. 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 paying any creative work.

[0018] Figure 1 It is a structural schematic 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 medium-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, the directional words used, such as "upper and lower", generally refer to the upper and lower parts of the device in normal use, and "inside and outside" refer to the outline of the device. In addition, the terms "first, second, third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first, second, third" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0022] At present, when the traditional coal-fired units are under low load conditions, the boilers cannot effectively regulate the supply of fuel and air, which may affect the performance and stability of the overall system. When peaking, the system operation is restricted by the boiler's stable combustion load, which limits the peak-shaving capacity of the unit. In addition, 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 achieve 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 medium-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 medium-pressure cylinder and the steam turbine low-pressure cylinder are coaxially arranged and connected to a 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 connected to each other, wherein the solid heat storage device is respectively connected to the superheater, the steam turbine high-pressure cylinder and the steam turbine medium-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 medium-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 components in the thermal system of the coal-fired generator set, the components in the high-temperature solid-state heat storage system, and connect the thermal system of the coal-fired generator set 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 generator set 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 tank 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 generator set also includes: a condenser 10, a water 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 steam turbine high-pressure cylinder 6 includes a steam inlet, a steam outlet and a steam extraction outlet, the steam turbine intermediate-pressure cylinder 7 includes a steam inlet, a steam outlet, a first-stage steam extraction outlet and a second-stage steam extraction outlet, and the steam turbine low-pressure cylinder 8 includes a steam inlet, a steam outlet and a steam extraction outlet; the steam outlet of the steam turbine high-pressure cylinder is connected to the steam inlet of the steam turbine intermediate-pressure cylinder, and the steam outlet of the steam turbine intermediate-pressure cylinder is connected to the steam inlet of the steam 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 medium inlet and a condensate medium outlet. The steam extraction outlet of the high-pressure cylinder 6 of the steam turbine is connected to the steam inlet of the high-pressure heater 17 through a pipeline. A first steam extraction heat recovery regulating valve 30 is provided between the steam extraction outlet of the high-pressure cylinder 6 of the steam turbine and the steam inlet of the high-pressure heater 17. The first steam extraction heat recovery regulating valve 30 is used to regulate the steam extraction flow. The first-stage steam extraction outlet of the intermediate-pressure cylinder 7 of the steam turbine is connected to the steam inlet of the high-pressure heater 17 through a pipeline. A second steam extraction heat recovery regulating valve 31 is provided on the pipeline between the first-stage steam extraction outlet of the intermediate-pressure cylinder 7 of the steam turbine and the steam inlet of the high-pressure heater 17. The second steam extraction heat recovery regulating valve 31 is used to regulate the steam extraction flow.

[0031] like Figure 1As shown, the deaerator 15 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 7 is connected to the steam inlet of the deaerator 15 through a pipeline. The pipeline between the second stage steam extraction outlet of the steam turbine intermediate pressure cylinder 7 and the steam inlet of the deaerator 15 is provided with a third steam extraction heat recovery regulating valve 32 for regulating the steam extraction flow. The low pressure heater 14 includes a steam inlet, a condensate medium inlet and a condensate medium outlet. The steam extraction outlet of the steam turbine low pressure cylinder 8 is connected to the steam inlet of the low pressure heater 14 through a pipeline. The condensate medium outlet of the low pressure heater 14 is connected to the feed water 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 feed water pump 16 and an air-water heat exchanger 18. The condenser 10 includes a condensate medium outlet, the steam outlet of the low-pressure cylinder 8 of the steam turbine is connected to the condenser 10 through a pipeline, the condensate medium outlet of the condenser 10 is connected to the condensate medium inlet of the low-pressure heater 14 through the condensate pump 13, the feed water medium outlet of the deaerator 15 is connected to the feed water medium of the high-pressure heater 17 through the feed water pump 16, and the inlet of the economizer 3 is connected to the feed water medium outlet of the high-pressure heater 17 through the air-water heat exchanger 18.

[0033] In the disclosed embodiment, 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 the high-temperature steam at the outlet of the superheater 2; the solid heat storage device 20 is connected to the high-pressure cylinder 6 of the steam turbine through a fourth regulating valve 29 and a pipeline, and is used to extract and store the high-temperature steam; the solid heat storage device 20 is connected to the intermediate-pressure cylinder 7 of the steam turbine through a fifth regulating valve 28 and a pipeline, and is used to extract and store the 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 the coal-fired unit is in the peak-shaving condition, the autonomous peak-shaving of the coal-fired unit is mainly achieved through two means: boiler combustion regulation and turbine load regulation. Among them, boiler combustion regulation is one of the main means to achieve flexible power generation peak-shaving of coal-fired units. Its basic principle is to control the heat output and steam generation of the boiler by adjusting the supply of fuel and air inside the boiler. In the specific implementation process, the operation of the coal-fired feeding system is precisely controlled to achieve dynamic adjustment of fuel supply to cope with changes in the load of the power grid; at the same time, the operating state of the fan is adjusted to change the air supply volume, optimize the combustion efficiency, and ensure that the boiler can maintain efficient combustion under different loads. This multi-dimensional adjustment method enables the boiler to respond quickly to fluctuations in power grid demand in a short time and give full play to its peak-shaving capacity. Compared with boiler regulation, turbine load regulation focuses on achieving changes in generator output power by adjusting steam flow and steam pressure. Specifically, the regulation of the steam turbine mainly depends on the fine control of the steam inlet valve and the exhaust valve. The adjustment of the valve opening directly affects the inflow of steam, thereby adjusting the power generation capacity of the steam turbine. To meet the dynamic load requirements of the power grid, steam turbine systems are usually equipped with real-time monitoring and automatic adjustment functions so that they can quickly track the load when power demand fluctuates. This steam turbine load adjustment mechanism, characterized by high precision and high stability, makes the switching between base load and peak load of coal-fired units smoother, optimizing the overall operating 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 a superheater, and then sequentially enters the high-pressure cylinder of a steam turbine, the intermediate-pressure cylinder of a steam turbine, and the low-pressure cylinder of a steam turbine to perform work, driving the generator to generate electricity, part of the high-temperature steam at the outlet of the superheater is extracted and introduced into a solid heat storage device, the heat storage device is continuously charged with heat, and heat storage preparation is completed; in the boiler low-load operation stage: the first steam extraction heat recovery regulating valve and the second steam 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 high-pressure cylinder of the steam turbine and the intermediate-pressure cylinder of the steam turbine 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 a coal-fired unit as an example, in the embodiment of the present disclosure, when the coal-fired unit system for deep peak load regulation is in operation, the path of the thermal cycle of the power generation cycle medium is as follows: Figure 1As shown. Specifically, after the coal-fired boiler is ignited, combustion generates high-temperature steam, and the generated steam is further heated by the economizer 3, the water-cooled wall 5, and the superheater 2 in sequence before entering the high-pressure cylinder 6 of the steam turbine; wherein, the main steam enters the high-pressure cylinder 6 of the steam turbine, the intermediate-pressure cylinder 7 of the steam turbine, and the low-pressure cylinder 8 of the steam turbine in sequence to expand and generate electricity, and at the same time, the high-pressure cylinder 6 of the steam turbine and the intermediate-pressure cylinder 7 of the steam turbine extract part of the steam to heat the feed water, reduce the amount of steam used for the steam turbine to work, and complete the power generation cycle under normal working conditions. The main steam expands step by step in the steam turbine, and after working in the high-pressure cylinder 6 of the steam turbine, the intermediate-pressure cylinder 7 of the steam turbine, and the low-pressure cylinder 8 of the steam turbine in sequence, the exhaust steam at the outlet of the low-pressure cylinder 8 of the steam turbine passes through the cooling water circuit composed of the condenser 10, the drying tower 11, and the circulating water pump 12 to condense and become condensed water, and then is transported to the low-pressure heater 14 by the condensate pump 13 for preliminary heating, and enters the deaerator 15 for deoxidation operation to obtain 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 disclosed embodiment, when the coal-fired power generation unit is operating in a deep peak-shaving state, the boiler operates at a 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 steam extraction heat recovery regulating valve 30 and the second steam 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 of 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 a low-load operation state.

[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 flow fan 19, and convectively exchanges heat with the high-temperature solid heat storage material in the solid heat storage device 20, releasing the heat stored in the solid heat storage device 20 into the air, and finally 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. The temperature of the high-temperature hot air after heat exchange is reduced, and it is further utilized and introduced into the induced draft fan 22 as the heat source of the air preheater 4, and the hot air produced is mixed with the coal powder for preheating. The boiler load is increased in disguise, the steam flow rate is increased, and the power generation efficiency and power generation load of the steam turbine unit are improved.

[0042] The system combines traditional coal-fired power generation units with high-temperature solid-state thermal storage systems, using solid-state thermal storage devices to store and release thermal energy, achieving more efficient energy utilization and heat recovery. It can not only relieve peak load pressure, but also improve overall energy utilization efficiency. Through the flexible cooperation of steam extraction and solid-state thermal storage devices, the coal-fired unit system for deep peak regulation has higher 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 is heat exchanged with the solid heat storage device 20 through the fourth regulating valve 29 and the pipeline; the high-temperature steam discharged from the intermediate-pressure cylinder 7 of the steam turbine is heat exchanged with the solid heat storage device 20 through the fifth regulating valve 28 and the pipeline.

[0044] In some embodiments, when the unit is in peak load operation, the boiler combustion regulation can be used to achieve dynamic regulation of the boiler thermal power output, such as adjusting the combustion parameters such as the amount of coal burned, the amount of air supplied, and the amount of induced draft, that is, the boiler load is reduced to reduce the amount of steam entering the turbine inlet, thereby adjusting the power output of the generator set. In the first embodiment of the present disclosure, specifically, the reduction in boiler load causes a reduction in the parameters of the steam entering the turbine. At this time, the first steam extraction heat recovery regulating valve 30, the second steam extraction heat recovery regulating valve 31, and the third heat recovery regulating valve 32 are closed, thereby increasing the amount of steam entering the turbine. For the electrical load increased by the reflux steam, the solid heat storage device 20 can be heated by the electric heating control device 27 to complete heat recovery.

[0045] In other embodiments, when the unit is in peak load regulation, the steam flow of the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder of the steam turbine can be flexibly reduced according to the peak load regulation depth requirements 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 steam 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 high-pressure cylinder 6 of the steam turbine has done work, extracting all the steam from the high-pressure cylinder 6 of the steam turbine after doing work, extracting part of the steam from the intermediate-pressure cylinder 7 of the steam turbine after doing work, and introducing it into the solid heat storage device 20 to heat the heat storage body to achieve different degrees of peak load regulation.

[0046] In the third embodiment of the present disclosure, when releasing energy, cold air is introduced through the axial flow fan 19, and convectively exchanges heat with the high-temperature solid heat storage material in the solid heat storage device 20, and finally heats it into high-temperature hot air. The high-temperature hot air further heats the feed water from the high-pressure heater to heat it into steam. The temperature of the high-temperature hot air after heat exchange is reduced, and it is further utilized and introduced into the fan 22 as the heat source of the air preheater 4, and the hot air is mixed with the coal powder for preheating. The boiler load is increased in disguise, the steam flow rate is increased, and the power generation efficiency and power generation load of the steam turbine unit are improved.

[0047] The coal-fired unit system for deep peak load regulation provided by the present invention and its operation method, by introducing the steam extraction and heat recovery technology, effectively improves the operation efficiency of the steam turbine by maintaining the steam flow when the load of the coal-fired unit is reduced, thereby realizing the efficient operation of the coal-fired unit under low load conditions and reducing the dependence on the stable combustion load of the boiler. At the same time, the system uses high-temperature solid-state heat storage technology to store the heat in the steam or flue gas extracted during the operation of the coal-fired unit in high-temperature solid-state heat storage materials. These materials can maintain heat energy for a long time at high temperature and release it quickly at peak load, providing additional heat energy support, further enhancing the peak load regulation capability and overall energy utilization efficiency of the unit.

[0048] The present invention provides a coal-fired unit system for deep peak regulation. When the boiler is running at low load, the steam flow rate of the steam turbine inlet is increased by extracting steam for heat recovery, thereby improving the power generation efficiency of the steam turbine. At the same time, when the boiler is under low load conditions to ensure safe and stable operation, the present invention provides a coal-fired unit system for deep peak regulation, which 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 a high-temperature solid-state heat storage system, and use this energy for peak regulation or electricity consumption as needed. The present invention couples high-temperature solid thermal energy storage technology, and can perform peak regulation of coal-fired generator sets alone and coupled peak regulation of the two, thereby improving the peak regulation depth and flexibility of coal-fired units.

[0049] The operating method of the coal-fired unit system for deep peak load regulation provided by the present invention forms a flexible peak load regulation solution by combining optimized structural design with precise steam extraction and operation strategies. This solution not only improves the adaptability of coal-fired units under different loads, but also effectively reduces the production cost per unit of electricity and improves the economic efficiency of power generation. Through more efficient combustion and energy conversion processes, the system also significantly reduces greenhouse gas emissions and has good environmental benefits.

[0050] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the specification and drawings of the present 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 load regulation, characterized in that: include: A thermal system of a coal-fired power generation unit, the thermal system of the 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, 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 a power grid through the generator; A high-temperature solid-state heat storage system, the high-temperature solid-state heat storage system comprising a solid heat storage device and an axial flow fan connected to each other, the solid heat storage device being respectively connected to the superheater, the high-pressure cylinder of the steam turbine and the intermediate-pressure cylinder of the steam turbine through different pipelines and regulating valves, and being 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 being used to perform heat exchange with the solid heat storage device; A plurality of regulating valves and a plurality of pipe sections, wherein the regulating valves include a first steam extraction heat recovery regulating valve, a second steam extraction heat recovery regulating valve and a third steam extraction heat recovery regulating valve, and the pipes are used to respectively connect the components in the thermal system of the coal-fired generator set and the components in the high-temperature solid-state heat storage system, and to connect the thermal system of the coal-fired generator set and the high-temperature solid-state heat 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 load regulation according to claim 1, characterized in that: The high-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet and a steam extraction outlet, the intermediate-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet, a first-stage steam extraction outlet and a second-stage steam extraction outlet, and the low-pressure cylinder of the steam turbine includes a steam inlet, a steam outlet and a steam 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 load 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 steam extraction outlet of the high-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater, and a first steam extraction heat recovery regulating valve is provided between the steam extraction outlet of the high-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater, the first-stage steam extraction outlet of the intermediate-pressure cylinder of the steam turbine is connected to the steam inlet of the high-pressure heater, and a second steam extraction heat recovery regulating valve is provided between the first-stage steam extraction outlet of the intermediate-pressure cylinder of the steam turbine and the steam inlet of the high-pressure heater, and the first steam extraction heat recovery regulating valve and the second steam extraction heat recovery regulating valve are used to adjust the steam extraction flow rate.

4. The coal-fired unit system for deep peak load 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, and a third steam extraction heat recovery regulating valve for adjusting the extraction flow rate 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 load 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 load 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 medium outlet. The steam outlet of the low-pressure cylinder of the steam turbine is connected to the condenser through a pipeline. The condensate medium outlet of the condenser is connected to the condensate medium inlet of the low-pressure heater through the condensate pump. The feed water medium outlet of the deaerator is connected to the feed water medium of the high-pressure heater through the feed water pump. The economizer inlet is connected to the feed water medium outlet of the high-pressure heater through the air-water heat exchanger.

7. The coal-fired unit system for deep peak load 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 the transmission of 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 the transmission of 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 air-water heat exchanger.

8. An operating method for a coal-fired unit system for deep peak load regulation according to any one of claims 1 to 7, characterized in that: Includes steps: During the boiler startup phase: after the coal-fired boiler is ignited, combustion generates high-temperature steam, which 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 outlet of the superheater is extracted and introduced into the solid heat storage device, which is continuously charged with heat to complete the heat storage preparation; During the low-load operation stage of the boiler: close the first extraction steam heat recovery regulating valve and the second extraction steam heat recovery regulating valve to allow the extraction steam to flow back from the deaerator and the high-pressure heater to the high-pressure cylinder and the intermediate-pressure cylinder of the steam turbine 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 to enter the economizer.

9. The method for operating a coal-fired unit system for deep peak load regulation according to claim 8, characterized in that: The method also 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.

Images