Coal-fired unit wide load peak shaving system, peak shaving method and storage medium

Abstract

The application relates to the technical field of deep load regulation of coal-fired units, in particular to a coal-fired unit wide-load regulation system, a regulation method and a storage medium, the system comprising a coal-fired unit, a molten salt heat storage and supply unit and a steam-electricity dual-drive induced draft fan power generation and heat supply unit, the molten salt heat storage and supply unit being connected with the coal-fired unit and the steam-electricity dual-drive induced draft fan power generation and heat supply unit respectively; a control unit determines a target operation mode according to the current total load of the system, and controls the system operation according to the target operation mode, so as to realize wide-load regulation of the coal-fired unit, the target operation mode comprising a first operation mode and a second operation mode, the control unit controls the steam-electricity dual-drive induced draft fan power generation and heat supply unit to generate power and the molten salt heat storage and supply unit to store heat in the first operation mode; and the control unit controls the coal-fired unit and the molten salt heat storage and supply unit to supply heat in the second operation mode. Therefore, the problems that wide-load efficient and stable regulation cannot be realized in the related art are solved.

Description

Technical Field

[0001] This application relates to the field of deep peak shaving technology for coal-fired power units, and in particular to a wide-load peak shaving system, peak shaving method and storage medium for coal-fired power units. Background Technology

[0002] With the increasing proportion of renewable energy power generation, coal-fired power units need to undertake frequent and deep peak shaving tasks, and wide-load operation has become the norm. However, under low-load conditions, the units are prone to problems such as steam parameters deviating from design values ​​and decreased combustion stability. Under high load conditions, they need to take into account both peak power generation and heating demand, which places higher demands on system flexibility and efficiency.

[0003] Related technologies typically employ a unified control strategy, which cannot optimize by region. Under low load, the turbine cylinder efficiency is significantly reduced, and the power generation efficiency deteriorates. Under high load, it is difficult to balance peak power generation and heating demand, resulting in unreasonable energy distribution and an inability to achieve efficient and stable peak shaving over a wide load range. Summary of the Invention

[0004] This application provides a wide-load peak-shaving system, peak-shaving method, and storage medium for coal-fired power units to solve the problems of inability to achieve efficient and stable peak-shaving over wide loads in related technologies.

[0005] The first aspect of this application provides a wide-load peak-shaving system for a coal-fired power unit, comprising: a coal-fired power unit, a molten salt thermal storage heating unit, and a steam-electric dual-drive induced draft fan power generation and heating unit, wherein the molten salt thermal storage heating unit is connected to both the coal-fired power unit and the steam-electric dual-drive induced draft fan power generation and heating unit; and a control unit, which is connected to the coal-fired power unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit, and determines the target operation based on the current total load of the coal-fired power unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit. The control unit controls at least one of the steam turbine generator unit, molten salt thermal storage heating unit, and steam-electric dual-drive induced draft fan power generation and heating unit according to the target operating mode to achieve peak shaving of the coal-fired unit over a wide load range. The target operating mode includes a first operating mode and a second operating mode. In the first operating mode, the control unit controls the steam-electric dual-drive induced draft fan power generation and heating unit to generate electricity while controlling the molten salt thermal storage heating unit to store heat. In the second operating mode, the control unit controls the coal-fired unit to generate electricity while controlling the molten salt thermal storage heating unit to supply heat.

[0006] Optionally, the coal-fired unit includes a boiler, a multi-stage turbine cylinder, a first generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, and a high-pressure heater. The boiler heats the first feedwater and / or the second feedwater to form first steam. The multi-stage turbine cylinder performs work on the first steam to drive the first generator to generate electricity and discharges second steam. The condenser cools the second steam to obtain condensate. The condensate pump performs a first pressurization on the condensate. The low-pressure heater heats the first pressurized condensate. The deaerator deoxygenates the heated condensate. The feedwater pump performs a second pressurization on the deoxygenated condensate. The high-pressure heater heats the second pressurized condensate to obtain second feedwater and / or second steam, and delivers the second feedwater and / or second steam to at least one of the boiler and the molten salt thermal storage heating unit.

[0007] Optionally, the molten salt thermal storage and heating unit includes a low-temperature molten salt tank, a low-temperature molten salt pump, a molten salt steam heater, a high-temperature molten salt tank, and a first flow regulating valve. The low-temperature molten salt tank is connected to one end of the low-temperature molten salt pump, the other end of the low-temperature molten salt pump is connected to the first end of the molten salt steam heater, the second end of the molten salt steam heater is connected to the high-temperature molten salt tank, and the first flow regulating valve is installed on the first pipe of the third end of the molten salt steam heater. The first flow regulating valve is connected to the steam pipe of the boiler or to the drainage pipe of the high-pressure heater. The fourth end of the molten salt steam heater is connected to the connecting pipe of the multi-stage steam turbine cylinder through a second pipe, and a second flow regulating valve is installed on the second pipe.

[0008] Optionally, the steam-electric dual-drive induced draft fan power generation and heating unit includes: an induced draft fan, a back pressure unit, a second generator, and a heating pipeline. The induced draft fan is connected to the back pressure unit, the air inlet of the back pressure unit is connected to the outlet of the molten salt steam heater, and the exhaust port of the back pressure unit is connected to the heating pipeline. The back pressure unit performs work based on the steam discharged from the molten salt steam heater to drive the second generator to generate electricity and introduces the discharged steam into the heating pipeline, which then supplies heat to the outside.

[0009] Optionally, the control unit is further configured to: if the current load is less than the preset load, the target operating mode is the first operating mode, and control the first flow regulating valve to connect to the steam pipe of the boiler and the second flow regulating valve to close based on the first operating mode; if the current load is greater than or equal to the preset load, the target operating mode is the second operating mode, and control the first flow regulating valve to connect to the drain pipe of the high-pressure heater and / or the second flow regulating valve to open based on the second operating mode.

[0010] Optionally, the first operating mode is as follows: the first steam is introduced into the molten salt steam heater through the first flow regulating valve, and the cryogenic molten salt pump is controlled to operate. The cryogenic molten salt pump introduces the cold molten salt in the cryogenic molten salt tank into the molten salt steam heater. The cold molten salt exchanges heat with the first steam, and the steam after heat exchange is introduced into the back pressure machine. The cold molten salt after heat exchange enters the high-temperature molten salt tank. The second operating mode is as follows: the second feed water and / or the second steam are introduced into the molten salt steam heater through the first flow regulating valve. At the same time, the hot molten salt in the high-temperature molten salt tank is introduced into the molten salt steam heater. The hot molten salt exchanges heat with the second feed water and / or the second steam, and the steam after heat exchange is introduced into the back pressure machine.

[0011] Optionally, the control unit is further configured to: in the first operating mode, if the volume of hot molten salt in the high-temperature molten salt tank reaches a preset volume, control the low-temperature molten salt pump to stop working and directly introduce the first steam into the back pressure machine.

[0012] Optionally, the control unit is further configured to: in the second operating mode, if the steam discharged from the back pressure turbine meets the target heating demand, control the second flow regulating valve to open and introduce the steam discharged from the back pressure turbine into the connecting pipe of the multi-stage turbine cylinder through the second pipe.

[0013] The second aspect of this application provides a method for wide-load peak shaving of coal-fired power units, based on the wide-load peak shaving system of the coal-fired power units described in the above embodiments, including the following steps: obtaining the current total load of the coal-fired power unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit; determining a target operating mode for at least one of the coal-fired power unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit based on the current total load; and controlling at least one of the coal-fired power unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit according to the target operating mode, so as to achieve wide-load range peak shaving of the coal-fired power unit.

[0014] A third aspect of this application provides a computer-readable storage medium having a computer program or instructions stored thereon, which is executed by a processor to perform the wide-load peak shaving method for coal-fired power units as described in the above embodiments.

[0015] The fourth aspect of this application provides a computer program product, including a computer program or instructions, which, when executed, implement the wide-load peak-shaving method for coal-fired power units as described in the above embodiments.

[0016] Therefore, this application has at least the following beneficial effects: This application presents a wide-load peak-shaving system for coal-fired power units, comprising a coal-fired power unit, a molten salt thermal energy storage and heating unit, a steam-electric dual-drive induced draft fan power generation and heating unit, and a control unit. By coupling the molten salt thermal energy storage and heating unit and the steam-electric dual-drive induced draft fan power generation and heating unit within the coal-fired power unit, the molten salt thermal energy storage and heating unit achieves cascaded storage and efficient conversion of steam energy. The control unit determines the system's target operating mode based on the current load, ensuring that power generation is undertaken by the most efficient power equipment, the steam turbine or back-pressure turbine, within a wide load range. This keeps the overall coal consumption for power generation at a low level, achieving deep peak shaving and efficient power generation, and comprehensively improving the operational flexibility and economy of the coal-fired power unit. Thus, it solves the technical problems of achieving efficient and stable peak shaving across wide loads in related technologies.

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

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of a wide-load peak-shaving system for a coal-fired power unit according to an embodiment of this application; Figure 2 This is a schematic diagram illustrating the principle of low-load peak shaving according to an embodiment of this application; Figure 3 This is a schematic diagram illustrating the principle of high-load peak shaving according to an embodiment of this application; Figure 4 This is a flowchart of a wide-load peak-shaving method for coal-fired power units provided according to an embodiment of this application. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0020] Currently, deep peak shaving of coal-fired power units faces problems such as unstable combustion at low loads and reduced steam parameters. Due to the reduced steam parameters and flow rate, the turbine's flow area deviates significantly from its optimal design condition, leading to a precipitous drop in cylinder efficiency (e.g., below 60% at 30% load). This directly causes a sharp deterioration in power generation efficiency and a significant increase in coal consumption for power supply, directly impacting the core economic issues. Simultaneously, insufficient turbine extraction capacity and parameters at low loads make it difficult to guarantee heating stability and quality. Furthermore, high-energy-consuming auxiliary systems (such as induced draft fans) further increase plant power consumption, amplifying the economic disadvantage. At a deeper level, the lack of large-scale, dispatchable thermal storage and system-level intelligent collaborative control in related technologies makes it impossible to perform spatiotemporal shifting and optimized allocation of unstable energy flows. Ultimately, this results in persistently high overall energy consumption levels for the unit across a wide load peak shaving range, creating an irreconcilable contradiction between deep peak shaving capacity and economic efficiency and heating demand.

[0021] To address this, this application constructs a wide-load peak-shaving system for coal-fired power units. By coupling a molten salt thermal storage system with a steam-electric dual-drive induced draft fan and implementing an intelligent operation strategy based on load critical points, it first achieves cascaded storage and efficient conversion of steam energy. Under low load, the superheated steam heat drives a high-efficiency back-compression turbine for power generation, directly overcoming the problem of degraded power generation efficiency caused by low turbine cylinder efficiency and significantly reducing coal consumption for power supply. Second, through back-compression turbine exhaust heat supply and molten salt thermal storage system heat source supplementation, it ensures stable and reliable heating across the entire load range, especially under low load, while simultaneously reducing plant power consumption. Finally, through system integration and intelligent control, it achieves dynamic optimal operation of the unit within a wide load peak-shaving range, unifying the three objectives of deep peak shaving, efficient power generation, and stable heating, comprehensively improving the operational flexibility and economic competitiveness of coal-fired power units.

[0022] Specifically, Figure 1 This is a schematic diagram of a wide-load peak-shaving system for a coal-fired unit provided in an embodiment of this application.

[0023] like Figure 1 As shown, the wide-load peak-shaving system 100 of the coal-fired unit includes: a coal-fired unit 101, a molten salt thermal storage and heating unit 102, a steam-electric dual-drive induced draft fan power generation and heating unit 103, and a control unit 104.

[0024] The molten salt thermal energy storage and heating unit 102 is connected to the coal-fired power unit 101 and the steam-electric dual-drive induced draft fan power generation and heating unit 103, respectively. The control unit 104 is connected to the coal-fired power unit 101, the molten salt thermal energy storage and heating unit 102, and the steam-electric dual-drive induced draft fan power generation and heating unit 103, respectively. It determines the target operating mode based on the current total load of the coal-fired power unit 101, the molten salt thermal energy storage and heating unit 102, and the steam-electric dual-drive induced draft fan power generation and heating unit 103, and controls the coal-fired power unit 101 and the molten salt thermal energy storage and heating unit 103 according to the target operating mode. At least one of unit 102 and steam-electric dual-drive induced draft fan power generation and heating unit 103 is used to achieve wide load range peak shaving of coal-fired unit 101. The target operating mode includes a first operating mode and a second operating mode. In the first operating mode, control unit 104 controls the steam-electric dual-drive induced draft fan power generation and heating unit 103 to generate electricity while controlling the molten salt thermal storage heating unit 102 to store heat. In the second operating mode, control unit 104 controls the coal-fired unit 101 to generate electricity while controlling the molten salt thermal storage heating unit 102 to supply heat.

[0025] It is understood that the embodiments of this application construct a wide-load peak-shaving system 100 for coal-fired units, including a coal-fired unit 101, a molten salt thermal storage heating unit 102, a steam-electric dual-drive induced draft fan power generation and heating unit 103, and a control unit 104. By coupling the molten salt thermal storage heating unit 102 and the steam-electric dual-drive induced draft fan power generation and heating unit 103 in the coal-fired unit 101, the molten salt thermal storage heating unit 102 realizes the cascade storage and efficient conversion of steam energy, and the control unit 104 determines the target operating mode of the system according to the current load, thereby ensuring that the power generation task is undertaken by the most efficient power equipment, the steam turbine or the back pressure turbine, within a wide load range. This keeps the overall coal consumption for power supply of the system at a low level, achieving deep peak shaving and efficient power generation, and comprehensively improving the operational flexibility and economy of the coal-fired unit.

[0026] The coal-fired power unit 101 in this embodiment can also be referred to as a steam turbine generator power generation system, the molten salt thermal storage heating unit 102 can also be referred to as a molten salt thermal storage heating system, the steam-electric dual-drive induced draft fan power generation heating unit 103 can also be referred to as a steam-electric dual-drive induced draft fan power generation heating system, and the control unit 104 can also be referred to as a heating load distribution intelligent control system; the coal-fired power unit 101, the molten salt thermal storage heating unit 102, and the steam-electric dual-drive induced draft fan power generation heating unit 103 can be collectively referred to as the unit.

[0027] Furthermore, in some embodiments of this application, the coal-fired unit 101 includes a boiler, a multi-stage steam turbine cylinder, a first generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, and a high-pressure heater.

[0028] The system includes: a boiler for heating first feedwater and / or second feedwater to form first steam; a multi-stage turbine cylinder for performing work on the first steam to drive a first generator to generate electricity and discharge second steam; a condenser for cooling the second steam to obtain condensate; a condensate pump for first pressurizing the condensate; a low-pressure heater for heating the first pressurized condensate; a deaerator for deoxygenating the heated condensate; a feedwater pump for second pressurizing the deoxygenated condensate; and a high-pressure heater for heating the second pressurized condensate to obtain second feedwater and / or second steam, and delivering the second feedwater and / or second steam to at least one of the boiler and the molten salt thermal storage heating unit.

[0029] The multi-stage steam turbine cylinder in this embodiment includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder; the first feedwater is water directly supplied to the boiler, and the second feedwater is feedwater generated after circulation through the coal-fired unit.

[0030] Specifically, such as Figure 2 As shown, the coal-fired power unit 101 in this embodiment includes a boiler 1 capable of reheating, a high-pressure turbine cylinder 2, a medium-pressure turbine cylinder 3, a low-pressure turbine cylinder 4, a generator 5, a condenser 6, a condensate pump 7, a low-pressure heater 8, a deaerator 9, a feedwater pump 10, and a high-pressure heater 11. Feedwater, heated by the boiler 1, enters the high-pressure turbine cylinder 2 to perform work. The exhaust steam from the high-pressure cylinder 2 re-enters the boiler 1 for heating, then enters the medium-pressure cylinder 3 to perform work. The exhaust steam from the medium-pressure cylinder 3 enters the low-pressure cylinder 4 to perform work, and after performing work, the exhaust gas enters the condenser 6 for cooling. The boiler 1 and the turbine are connected via a steam pipeline. Condensate, pressurized by the condensate pump 7, is heated by the low-pressure heater 8, enters the deaerator 9, is pressurized again by the feedwater pump 10, and then heated by the high-pressure heater 11 before entering the boiler 1.

[0031] Furthermore, in some embodiments of this application, the molten salt thermal storage and heating unit 102 includes a low-temperature molten salt tank, a low-temperature molten salt pump, a molten salt steam heater, a high-temperature molten salt tank, and a first flow regulating valve.

[0032] The cryogenic molten salt tank is connected to one end of the cryogenic molten salt pump, the other end of the cryogenic molten salt pump is connected to the first end of the molten salt steam heater, the second end of the molten salt steam heater is connected to the high-temperature molten salt tank, and the first flow regulating valve is installed on the first pipe of the third end of the molten salt steam heater. The first flow regulating valve is connected to the steam pipe of the boiler or to the drainage pipe of the high-pressure heater. The fourth end of the molten salt steam heater is connected to the connecting pipe of the multi-stage steam turbine cylinder through the second pipe, and the second pipe is equipped with the second flow regulating valve.

[0033] Specifically, such as Figure 2 As shown and Figure 3As shown, the molten salt thermal storage and heating unit 102 of this application embodiment includes a first flow regulating valve 12 (also referred to as a steam flow regulating valve for a molten salt steam heater), a low-temperature molten salt tank 13, a low-temperature molten salt pump 14, a molten salt steam heater 15, and a high-temperature molten salt tank 16. The low-temperature molten salt tank 13 is connected to one end of the low-temperature molten salt pump 14, the other end of the low-temperature molten salt pump 12 is connected to the first end of the molten salt steam heater 15, the second end of the molten salt steam heater 15 is connected to the high-temperature molten salt tank, and the first flow regulating valve 12 is provided on the first pipe of the third end of the molten salt steam heater 15. The first flow regulating valve 12 is connected to the steam pipe of the boiler 1 or to the drain pipe of the high-pressure heater 11. The fourth end of the molten salt steam heater 15 is connected to the connecting pipe of the multi-stage steam turbine cylinder through a second pipe, and a second flow regulating valve 21 is provided on the second pipe.

[0034] Furthermore, it should be noted that the molten salt in the embodiments of this application can be replaced with other heat storage media, such as high-pressure hot water.

[0035] Furthermore, in some embodiments of this application, the steam-electric dual-drive induced draft fan power generation and heating unit 103 includes: an induced draft fan, a back pressure machine, a second generator, and a heating pipeline.

[0036] The induced draft fan is connected to the back pressure unit. The air inlet of the back pressure unit is connected to the outlet of the molten salt steam heater. The exhaust port of the back pressure unit is connected to the heating pipeline. The back pressure unit performs work based on the steam discharged from the molten salt steam heater to drive the second generator to generate electricity and introduces the discharged steam into the heating pipeline, which then supplies heat to the outside.

[0037] The induced draft fan in this embodiment can also be referred to as the induced draft fan section, the back pressure unit can also be referred to as the induced draft fan back pressure unit section, and the second generator can also be referred to as the back pressure unit generator section.

[0038] Specifically, such as Figure 2 and Figure 3 As shown, the steam-electric dual-drive induced draft fan power generation and heating unit 103 of this application embodiment includes an induced draft fan 17, a back pressure unit 18, a second generator 19, and a heating pipe 20. The induced draft fan is connected to the back pressure unit. The air inlet of the back pressure unit 18 is connected to the outlet of the molten salt steam heater 15. The exhaust port of the back pressure unit 18 is connected to the heating pipe 20. The back pressure unit performs work based on the steam discharged from the molten salt steam heater 15 to drive the second generator 19 to generate electricity and introduces the discharged steam into the heating pipe 20. The heating pipe 20 provides heat to the outside.

[0039] Furthermore, in some embodiments of this application, the control unit 104 is further configured to: if the current load is less than or equal to the preset load, the target operating mode is the first operating mode, and based on the first operating mode, control the first flow regulating valve to connect to the steam pipe of the boiler and the second flow regulating valve to close; if the current load is greater than the preset load, the target operating mode is the second operating mode, and based on the second operating mode, control the first flow regulating valve to connect to the drain pipe of the high-pressure heater and / or the second flow regulating valve to open.

[0040] The preset load is the load critical point, which can be determined by theoretical calculation, experimental calibration, etc. The first operating mode is the low load operating mode, in which the back pressure turbine is used for power generation first, and the molten salt thermal storage heating unit 102 is used for thermal storage. The second operating mode is the high load operating mode, in which the steam turbine is used for power generation first, and the molten salt thermal storage heating unit 102 is used for heating.

[0041] It is understood that, in the embodiments of this application, when the current load is less than or equal to the preset load, the target operating mode is the first operating mode. According to the first operating mode, the first flow regulating valve is connected to the steam pipe of the boiler, and the second flow regulating valve is closed to give priority to the back pressure generator for power generation. When the current load is greater than the preset load, the target operating mode is the second operating mode. According to the second operating mode, the first flow regulating valve is connected to the drain pipe of the high-pressure heater, and the second flow regulating valve is opened to give priority to the steam turbine for power generation.

[0042] Specifically, under low load operation, the cylinder efficiency of each stage of the steam turbine is far lower than that under rated load. Below 30% load, the cylinder efficiency is even lower than 60%, which is more than 30% lower than the rated load, resulting in a power generation efficiency far lower than the rated load. Furthermore, under low load, the unit's heating parameters require the use of superheated steam with higher quality steam. This steam must be depressurized and decooled before entering the back compressor for heating, resulting in throttling heat loss. Therefore, in this embodiment, under low load operation, superheated steam can be extracted to heat the molten salt first. Once the temperature parameters are reduced to meet the back compressor's inlet steam parameters, the steam can then enter the back compressor for power generation. The exhaust steam from the back compressor can be used to heat or preheat the molten salt. Additionally, under low load, the back compressor cylinder efficiency can be stably maintained above 80%, which is more than 20% higher than the steam turbine cylinder efficiency under lower load. Therefore, under low load, the back compressor can be prioritized for power generation and connected to the plant power system. Once the load increases to a level where the steam turbine cylinder efficiency is greater than or equal to the back compressor cylinder efficiency, the steam turbine can be prioritized for power generation, and adjustments can be made in conjunction with the heating load.

[0043] At high loads, the turbines are prioritized for peak power generation due to their high power generation efficiency.

[0044] The load critical point in this application embodiment is not a fixed value, but a dynamic, intelligent judgment benchmark based on real-time energy efficiency comparison. Specifically, it is the load point at which the turbine generator set and the steam-electric dual-drive induced draft fan back-pressure turbine unit have equal power generation efficiencies. The physical essence of this critical point is the balance point between the turbine cylinder efficiency and the back-pressure turbine cylinder efficiency. Under low load (e.g., below 30% of rated load), the turbine cylinder efficiency can be as low as below 60%, while the back-pressure turbine cylinder efficiency can remain stable above 80%. As the load increases, the turbine steam parameters improve, and its cylinder efficiency gradually recovers, reaching or even exceeding the high-efficiency range of the back-pressure turbine at a certain load point.

[0045] The critical point L can be determined in the following way: 1. Theoretical calculation: Based on the unit's design parameters, the power generation efficiency curves of the steam turbine and back pressure unit under different loads are simulated through thermodynamic calculations, and their intersection is the theoretical critical point.

[0046] 2. Experimental calibration: During actual operation of the unit, by installing power and flow measurement devices, the actual working efficiency of the turbine and back pressure unit under different loads is measured, and the precise critical load range is determined by data fitting.

[0047] 3. Dynamic correction: The intelligent control system can adjust the boiler combustion efficiency, ambient temperature, and molten salt heat storage based on these parameters.

[0048] Furthermore, in some embodiments of this application, the first operating mode is as follows: first steam is introduced into the molten salt steam heater through the first flow regulating valve, and the cryogenic molten salt pump is controlled to operate. The cryogenic molten salt pump introduces cold molten salt from the cryogenic molten salt tank into the molten salt steam heater. The cold molten salt exchanges heat with the first steam, and the steam after heat exchange is introduced into the back pressure machine. The cold molten salt after heat exchange enters the high-temperature molten salt tank. The second operating mode is as follows: second feed water and / or second steam are introduced into the molten salt steam heater through the first flow regulating valve, and hot molten salt from the high-temperature molten salt tank is introduced into the molten salt steam heater. The hot molten salt exchanges heat with the second feed water and / or second steam, and the steam after heat exchange is introduced into the back pressure machine.

[0049] Specifically, the peak-shaving principle of this application embodiment under low load is as follows: Figure 2As shown, when the unit is running at low load, the turbine power generation efficiency is low and the boiler main reheat steam parameters deviate from the design operating parameters. At this time, the steam source of the steam-electric dual-drive induced draft fan back compressor 18 needs to be the boiler main steam with higher parameters. After passing through the molten salt steam heater 15 for de-temperature and pressure reduction, it enters the steam-electric dual-drive induced draft fan back compressor 18 to do work. At this time, according to the demand of the power load, the steam entering the induced draft fan back compressor 18 is adjusted by the first flow regulating valve 12 to make the second generator 19 of the back compressor 18 generate electricity as much as possible. The excess power generation, except for driving the induced draft fan 17, can be used for plant power consumption, reducing the plant power consumption rate of the low-load unit. The exhaust steam is used for unit heating 20 under low load. The cold molten salt in the low-temperature molten salt tank enters the molten salt steam heater 15 through the low-temperature molten salt pump 14 to exchange heat with the high-temperature steam. The high-temperature molten salt after heat exchange enters the high-temperature molten salt tank 16.

[0050] The embodiments of this application utilize the peak-shaving principle under high loads, as follows: Figure 3 As shown, when operating at high load, the turbine's power generation efficiency has increased with the increase in main reheat steam parameters (up to over 90%), exceeding the cylinder efficiency of the back-compression turbine. The turbine generator set 5 prioritizes peak power generation. At this time, the steam source for the dual-drive induced draft fan and back-compression turbine 18 needs to be steam heated by molten salt. Boiler feedwater is heated by the condenser 6, low-pressure heater 8, deaerator 9, and high-pressure heater 11, and then pressurized by the condensate pump 7 and feedwater pump 10. Based on the heating load demand, the flow is regulated by the first flow regulating valve 12. The amount of steam entering the molten salt steam heater 15 is adjusted. The heated steam enters the back pressure of the steam-electric dual-drive induced draft fan 18 to do work, and the exhaust steam is used for unit heating 20 under low load. The hot molten salt in the high temperature molten salt tank 13 enters the molten salt steam heater 15 through the high temperature molten salt pump to exchange heat with the low temperature feedwater. The low temperature molten salt after heat exchange enters the low temperature molten salt tank 13. When the heat release of the high temperature molten salt tank reaches the upper limit, the high temperature molten salt pump stops working and re-enters the molten salt heat storage process. Reheat steam (such as the exhaust steam of the high pressure cylinder 2) can be selected as the heating source.

[0051] Furthermore, in some embodiments of this application, the control unit 104 is further configured to: in the first operating mode, if the volume of hot molten salt in the high-temperature molten salt tank reaches a preset volume, control the low-temperature molten salt pump to stop working and directly introduce the first steam into the back pressure machine.

[0052] The preset volume can be the volume of the high-temperature molten salt tank.

[0053] It is understood that in the first operating mode of this application embodiment, if the volume of hot molten salt in the high-temperature molten salt tank reaches the preset volume, the low-temperature molten salt pump is controlled to stop working, and the first steam is directly introduced into the back pressure machine, that is, the steam enters the back pressure machine without heat exchange.

[0054] Further, in some embodiments of the present application, the control unit 104 is further configured to: in the second operation mode, if the steam discharged from the back pressure turbine meets the target heating demand, control the second flow regulating valve to open, and introduce the steam discharged from the back pressure turbine into the connecting pipeline of the multi-stage steam turbine cylinder through the second pipeline.

[0055] It can be understood that in the second operation mode of the embodiments of the present application and on the premise of meeting the heating demand, the surplus superheated steam can be adjusted through the second flow regulating valve 21 to enter the high-pressure cylinder of the steam turbine or a suitable access position to participate in peak power generation, thereby improving the power generation efficiency of the entire system.

[0056] The control unit of the embodiments of the present application is the core for realizing the switching based on the load critical point, and includes: 1. Data perception layer: including load sensors, temperature sensors, pressure sensors, flow meters, etc. distributed on the boiler, steam turbine, back pressure turbine, molten salt system and heating pipeline network, which are used to collect data such as the power generation load of the unit, main steam / reheat steam parameters, inlet and outlet parameters of the back pressure turbine, molten salt temperature and flow, and heating demand in real time.

[0057] 2. Decision control layer: the intelligent brain of the system, the core of which is a control unit (such as DCS or PLC) with a built-in load critical point judgment algorithm and optimized operation strategy. This unit receives the data from the perception layer, calculates the relative efficiency of the steam turbine and the back pressure turbine under the current total load in real time, and compares it with the preset L, and accordingly generates control instructions.

[0058] 3. Execution layer: including the first flow regulating valve, the steam inlet regulating valve of the back pressure turbine (i.e., the second flow regulating valve), and a three-way valve or other shut-off valves for switching the steam source path, etc. They receive the instructions of the control unit and accurately adjust the medium flow and path.

[0059] Specifically, the control process of the wide load peak shaving system of the embodiments of the present application is as follows: system initialization and parameter setting: the control system starts and loads the preset load critical point L and its floating range; real-time data collection and monitoring: continuously monitor the real-time power generation load (Lc) of the unit and the heating demand; load interval judgment and decision-making.

[0060] 1. When Lc < L (low load condition).

[0061] Control strategy: The system determines that it is currently in the "low efficiency area of the steam turbine", and preferentially starts the high-efficiency power generation mode of the back pressure turbine.

[0062] Actions: The main steam from the boiler is preferentially directed to the molten salt steam heater, where precise cooling and pressure reduction are achieved using molten salt, significantly minimizing throttling losses. The first flow regulating valve 1) controls the heat-exchanged steam to enter the back compressor of the dual-drive induced draft fan to perform work. The electricity generated by the second generator is preferentially used to drive the induced draft fan, with surplus electricity connected to the plant's auxiliary power system, directly reducing the plant's auxiliary power rate. The exhaust steam from the back compressor is used to ensure stable heating under low load conditions. In this mode, the turbine generator set maintains low load operation or only undertakes basic load.

[0063] 2. When Lc ≥ L (high load condition).

[0064] Control strategy: The system determines that it is currently in the "high-efficiency zone of the steam turbine" and prioritizes starting the peak power generation mode of the steam turbine.

[0065] Action Execution: Switch the steam source path to prioritize the main boiler steam and reheat steam to the turbine generator set for power generation, achieving peak power generation. The molten salt thermal storage heating system switches to "prioritize heating": A portion of the feedwater or low-temperature steam is controlled to enter the molten salt steam heater via the first flow regulating valve. The high-temperature molten salt heats the steam to meet the required parameters, driving the back-pressure turbine. The exhaust steam is used for heating. If the heating demand is met and there is surplus molten salt heat and steam, the surplus steam can be redirected back to a suitable part of the turbine (such as the high-pressure cylinder inlet) via the second flow regulating valve to participate in peak power generation, further improving system efficiency.

[0066] Furthermore, the control unit does not simply perform "on / off" switching. When Lc fluctuates slightly around L, the system introduces a hysteresis algorithm to prevent frequent switching and ensure stable operation. At the same time, the system continuously learns the optimal operating parameters under different operating conditions, fine-tuning L and the control strategy to achieve adaptive optimization over long-term operation.

[0067] The wide-load peak-shaving system for coal-fired power units in this application embodiment ensures that, within a wide load range, power generation is always undertaken by the most efficient power equipment (steam turbine or back-pressure turbine) through intelligent judgment of load critical points, thereby keeping the overall coal consumption for power supply at a low level and improving overall power generation efficiency. The intelligent switching logic and hysteresis design avoid frequent system switching caused by normal load fluctuations, ensuring the stability and safety of unit operation. Decoupling power generation from heating allows for stable and reliable heating through the synergy of the molten salt system and back-pressure turbine, regardless of the unit's load, greatly improving the unit's peak-shaving flexibility and overall energy utilization efficiency. Molten salt thermal storage also reduces desuperheating and pressure reduction losses before steam inlet, resulting in stable heating and reduced energy consumption.

[0068] In summary, the embodiments of this application systematically solve the key technical problems in deep peak shaving of coal-fired units by coupling the molten salt thermal storage heating system with the steam-electric dual-drive induced draft fan technology and applying an intelligent operation strategy based on the load critical point, so as to achieve efficient and stable operation under wide load conditions.

[0069] First, by introducing a molten salt thermal storage system to utilize superheated steam in a cascade manner, and leveraging the high efficiency of the dual-drive steam-electric back-pressure turbine under low load, the core problem of the sharp decline in turbine system cycle efficiency under deep peak-shaving conditions is solved. Specifically, under deep peak-shaving loads (such as below 30% of rated load), steam parameters deviate significantly from design values, and turbine cylinder efficiency even falls below 60%, leading to deterioration in power generation efficiency and a significant increase in coal consumption for power supply.

[0070] Secondly, by reconstructing the coordinated operation of the thermal system and the steam-electric dual-drive induced draft fan, the problem of coordinating the increase in plant power consumption and insufficient heating capacity under low load can be solved. Existing technologies cannot provide a stable, high-parameter heating source under low load, and the high power consumption of auxiliary equipment restricts the economic efficiency of the unit.

[0071] Furthermore, by utilizing the thermal inertia buffering effect of the molten salt thermal storage system and the multi-purpose characteristics of the back pressure turbine exhaust steam, the operational bottleneck caused by reduced boiler efficiency and difficulty in maintaining the main and reheat steam temperatures can be resolved, ensuring combustion stability and parameter maintenance capabilities under low load.

[0072] Finally, by constructing a system-level solution integrating molten salt thermal storage, steam-electric dual drive, and intelligent control, the fundamental defects of related technologies and strategies being singular and lacking dynamic optimization capabilities are overcome. This enables the spatiotemporal shift and optimal allocation of energy within a wide load range, improves the power generation efficiency of coal-fired power units under low load, reduces the plant power consumption rate under low load, reduces heat loss during the heating process, solves the problem of insufficient heat source for low load heating, and ultimately breaks through the energy consumption bottleneck under deep peak shaving of the unit, improving the comprehensive peak shaving capability and economy.

[0073] The wide-load peak-shaving system for coal-fired power units proposed in this application includes a coal-fired power unit, a molten salt thermal storage heating unit, a steam-electric dual-drive induced draft fan power generation and heating unit, and a control unit. By coupling the molten salt thermal storage heating unit and the steam-electric dual-drive induced draft fan power generation and heating unit in the coal-fired power unit, the molten salt thermal storage heating unit realizes the cascade storage and efficient conversion of steam energy, and the control unit determines the target operating mode of the system according to the current load. This ensures that, within a wide load range, the power generation task is undertaken by the most efficient power equipment at present, the steam turbine or the back pressure turbine, thereby keeping the overall coal consumption for power supply of the system at a low level, achieving deep peak shaving and efficient power generation, and comprehensively improving the operational flexibility and economy of the coal-fired power unit.

[0074] Next, referring to the accompanying drawings, a wide-load peak-shaving method for coal-fired power units according to embodiments of this application is described.

[0075] Figure 4 This is a flowchart of a wide-load peak-shaving method for coal-fired power units according to an embodiment of this application.

[0076] like Figure 4 As shown, this wide-load peak-shaving method for coal-fired power units, based on the aforementioned wide-load peak-shaving system for coal-fired power units, includes the following steps: In step S101, the current total load of the coal-fired unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit is obtained.

[0077] In step S102, a target operating mode is determined for at least one of the following: coal-fired unit, molten salt thermal storage heating unit, and steam-electric dual-drive induced draft fan power generation and heating unit, based on the current total load.

[0078] In step S103, at least one of the coal-fired power unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit is controlled according to the target operating mode to achieve peak shaving of the coal-fired power unit over a wide load range.

[0079] It should be noted that the foregoing explanation of the embodiment of the wide-load peak-shaving system for coal-fired units also applies to the wide-load peak-shaving method of the coal-fired units in this embodiment, and will not be repeated here.

[0080] According to the wide-load peak shaving method for coal-fired power units proposed in the embodiments of this application, the target operating mode of the system can be determined according to the current load, thereby ensuring that the power generation task is undertaken by the most efficient power equipment, such as steam turbine or back pressure turbine, within a wide load range. This keeps the overall coal consumption for power supply of the system at a low level, achieving deep peak shaving and efficient power generation, and comprehensively improving the operational flexibility and economy of coal-fired power units.

[0081] This application also provides a computer-readable storage medium storing a computer program or instructions thereon, which, when executed by a processor, implements the above-described wide-load peak-shaving method for coal-fired power units.

[0082] This application also provides a computer program product, including a computer program or instructions, which, when executed, implement the above-described wide-load peak shaving method for coal-fired power units.

[0083] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0085] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0086] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or more of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (FPGAs), field-programmable gate arrays (FPGAs), etc.

[0087] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

Claims

1. A wide-load peak-shaving system for coal-fired power units, characterized in that, in, The system includes: The system includes a coal-fired power unit, a molten salt thermal storage and heating unit, and a steam-electric dual-drive induced draft fan power generation and heating unit, wherein the molten salt thermal storage and heating unit is connected to the coal-fired power unit and the power generation and heating unit, respectively. A control unit is connected to the coal-fired power unit, the molten salt thermal energy storage and heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit, respectively. The control unit determines a target operating mode based on the current total load of the coal-fired power unit, the molten salt thermal energy storage and heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit, and controls at least one of these units according to the target operating mode to achieve wide-range peak shaving for the coal-fired power unit. The target operating mode includes a first operating mode and a second operating mode. In the first operating mode, the control unit controls the steam-electric dual-drive induced draft fan power generation and heating unit to generate electricity while simultaneously controlling the molten salt thermal energy storage and heating unit to store heat. In the second operating mode, the control unit controls the coal-fired power unit to generate electricity while simultaneously controlling the molten salt thermal energy storage and heating unit to supply heat.

2. The wide-load peak-shaving system for coal-fired power units according to claim 1, characterized in that, The coal-fired power unit includes a boiler, a multi-stage steam turbine cylinder, a first generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, and a high-pressure heater. The boiler is used to heat the first feedwater and / or the second feedwater to form the first steam. The multi-stage steam turbine cylinder is used to perform work on the first steam to drive the first generator to generate electricity and to discharge the second steam. The condenser is used to cool the second steam to obtain condensate; The condensate pump is used to initially pressurize the condensate. The low-pressure heater is used to heat the condensate after the first pressurization. The deaerator is used to deoxygenate the heated condensate. The water supply pump is used to pressurize the deoxygenated condensate a second time. The high-pressure heater is used to heat the condensate after the second pressurization to obtain second feedwater and / or second steam, and to deliver the second feedwater and / or second steam to at least one of the boiler and the molten salt thermal storage heating unit.

3. The wide-load peak-shaving system for coal-fired power units according to claim 2, characterized in that, The molten salt thermal storage and heating unit includes a low-temperature molten salt tank, a low-temperature molten salt pump, a molten salt steam heater, a high-temperature molten salt tank, and a first flow regulating valve. The low-temperature molten salt tank is connected to one end of the low-temperature molten salt pump, the other end of the low-temperature molten salt pump is connected to the first end of the molten salt steam heater, and the second end of the molten salt steam heater is connected to the high-temperature molten salt tank. A first flow regulating valve is provided on the first pipe at the third end of the molten salt steam heater. The first flow regulating valve is connected to the steam pipe of the boiler or to the drain pipe of the high-pressure heater. The fourth end of the molten salt steam heater is connected to the connecting pipe of the multi-stage steam turbine cylinder through a second pipe, and a second flow regulating valve is provided on the second pipe.

4. The wide-load peak-shaving system for coal-fired power units according to claim 3, characterized in that, The steam-electric dual-drive induced draft fan power generation and heating unit includes: an induced draft fan, a back pressure unit, a second generator, and a heating pipeline. The induced draft fan is connected to the back pressure unit, the air inlet of the back pressure unit is connected to the outlet of the molten salt steam heater, and the exhaust port of the back pressure unit is connected to the heating pipeline. The back pressure unit performs work based on the steam discharged from the molten salt steam heater to drive the second generator to generate electricity and introduces the discharged steam into the heating pipeline, which supplies heat to the outside.

5. The wide-load peak-shaving system for coal-fired power units according to claim 4, characterized in that, The control unit is further used for: If the current load is less than the preset load, the target operating mode is the first operating mode, and based on the first operating mode, the first flow regulating valve is connected to the steam pipe of the boiler, and the second flow regulating valve is closed. If the current load is greater than or equal to the preset load, the target operating mode is the second operating mode, and based on the second operating mode, the first flow regulating valve is connected to the drain pipe of the high-pressure heater, and / or the second flow regulating valve is opened.

6. The wide-load peak-shaving system for coal-fired power units according to claim 5, characterized in that, The first operating mode is as follows: the first steam is introduced into the molten salt steam heater through the first flow regulating valve, and the low temperature molten salt pump is controlled to work. The low temperature molten salt pump introduces the cold molten salt in the low temperature molten salt tank into the molten salt steam heater. The cold molten salt exchanges heat with the first steam. The steam after heat exchange is introduced into the back pressure machine. The cold molten salt after heat exchange enters the high temperature molten salt tank. The second operating mode is as follows: the second feed water and / or the second steam are introduced into the molten salt steam heater through the first flow regulating valve, and the hot molten salt in the high-temperature molten salt tank is introduced into the molten salt steam heater. The hot molten salt exchanges heat with the second feed water and / or the second steam, and the third steam after heat exchange is introduced into the back pressure machine.

7. The wide-load peak-shaving system for coal-fired power units according to claim 6, characterized in that, The control unit is further configured to: in the first operating mode, if the volume of hot molten salt in the high-temperature molten salt tank reaches a preset volume, control the low-temperature molten salt pump to stop working and directly introduce the first steam into the back pressure machine.

8. The wide-load peak-shaving system for coal-fired power units according to claim 6, characterized in that, The control unit is further configured to: in the second operating mode, if the steam discharged from the back pressure unit meets the target heating demand, control the second flow regulating valve to open and introduce the steam discharged from the back pressure unit into the connecting pipe of the multi-stage steam turbine cylinder through the second pipe.

9. A method for wide-load peak shaving of coal-fired power units, characterized in that, The method is implemented based on the wide-load peak-shaving system for coal-fired power units as described in any one of claims 1-8, wherein the method includes the following steps: Obtain the current total load of the coal-fired unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit; Based on the current total load, determine the target operating mode of at least one of the coal-fired unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit; Control at least one of the coal-fired power unit, the molten salt thermal storage heating unit, and the steam-electric dual-drive induced draft fan power generation and heating unit according to the target operating mode to achieve peak shaving of the coal-fired power unit over a wide load range.

10. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, The computer program or instructions are executed by a processor to implement the wide-load peak shaving method for coal-fired power units as described in claim 9.

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