Full-load denitration system and method based on fused salt heat storage

Abstract

The invention provides a full-load denitration system and method based on fused salt heat storage. The full-load denitration system comprises a fused salt heat storage unit which is in heat exchange connection with a denitration system of a coal power unit; the fused salt heat storage unit comprises a fused salt circulation loop composed of a fused salt cold tank, a steam condenser, a fused salt hot tank and a heat exchange assembly. The heat exchange assembly comprises a first heat exchange piece and a second heat exchange piece. During peak regulation of the coal power unit, low-temperature fused salt in the fused salt circulation loop exchanges heat with steam output from the coal power unit through the steam condenser and generates high-temperature fused salt, and the high-temperature fused salt exchanges heat with circulating flue gas of the denitration system through the second heat exchange piece so as to keep the optimal temperature of the flue gas at the inlet of the denitration system. Large-capacity, high-quality, high-density and low-pressure energy storage is achieved, meanwhile, during deep peak regulation or starting of the coal power unit, a part of stored heat is conveyed to an inlet of a denitration system, the flue gas temperature of the denitration system is increased to an optimal temperature window of a catalyst, and full-load denitration of the coal power unit is achieved.

Description

Technical Field

[0001] This application relates to the field of boiler technology, and in particular to a full-load denitrification system and method based on molten salt thermal storage. Background Technology

[0002] To further reduce the energy consumption of coal-fired power units, enhance their flexibility and regulation capabilities, improve their clean and efficient operation, and promote the clean and low-carbon transformation of the power industry, the general requirement for peak-shaving capacity under pure condensing conditions is that the minimum power output reaches 35% of the rated load. During the heating season, heating cogeneration units should strive to achieve a peak-shaving capacity of 40% of the rated load for a minimum power output of 6 hours per day through thermal decoupling. Other types of units should take measures to minimize the minimum power output.

[0003] Coal-fired power units have large basic capacities, requiring large-capacity peak-shaving systems. Molten salt thermal energy storage is a type of sensible heat storage using molten inorganic salts, utilizing temperature changes in the molten salt to store heat. A dual-tank molten salt thermal energy storage system is typically used. Molten salt thermal energy storage is mostly applied in solar thermal power plants and rarely used in peak-shaving systems for large coal-fired power units. Furthermore, during deep peak-shaving processes in coal-fired power units, the operating temperature of the denitrification system is below the optimal operating temperature range, leading to reduced denitrification efficiency and increased nitrogen oxide concentrations. Existing full-load denitrification technologies rely on flue gas bypass or water system modifications, which suffer from problems such as large workloads, limited effectiveness, and frequent operational failures. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related technologies. Therefore, the purpose of this application is to propose a full-load denitrification system and method based on molten salt thermal storage. This system utilizes molten salt as the thermal storage medium for the deep peak-shaving system of coal-fired power units, achieving large-capacity, high-quality, high-density, and low-pressure energy storage. Simultaneously, during deep peak-shaving or startup of the coal-fired power unit, a portion of the stored thermal energy is transported to the inlet of the denitrification system, raising the flue gas temperature of the denitrification system to the optimal temperature window of the catalyst, thereby achieving full-load denitrification of the coal-fired power unit.

[0005] To achieve the above objectives, a full-load denitrification system based on molten salt thermal storage is proposed according to the first aspect of this application, which includes a molten salt thermal storage unit connected to the denitrification system of a coal-fired power unit for heat exchange.

[0006] The molten salt thermal storage unit includes a molten salt circulation loop consisting of a molten salt cold tank, a steam condenser, a molten salt hot tank, and a heat exchange assembly. The heat exchange assembly includes a first heat exchanger and a second heat exchanger. During peak shaving of the coal-fired power unit, the low-temperature molten salt in the molten salt circulation loop exchanges heat with the steam output from the coal-fired power unit through the steam condenser to generate high-temperature molten salt. The high-temperature molten salt exchanges heat with the circulating flue gas of the denitrification system through the second heat exchanger to maintain the optimal temperature of the flue gas at the inlet of the denitrification system.

[0007] In some embodiments, along the flow direction of the flue gas, the denitrification system includes an economizer, a denitrification device, an air preheater, a dust collector, an induced draft fan, and a desulfurization tower connected upstream and downstream; and a flue gas circuit is provided between the outlet of the induced draft fan and the inlet of the denitrification device, and the second heat exchanger is provided on the flue gas circuit.

[0008] In some embodiments, a flue gas thermometer is installed at the inlet of the denitrification device.

[0009] In some embodiments, both the molten salt cold tank and the molten salt hot tank are equipped with a cold tank level gauge and a hot tank level gauge.

[0010] In some embodiments, the high-temperature molten salt exchanges heat with the circulating water output from the coal-fired power unit through the first heat exchanger to cool the high-temperature molten salt.

[0011] In some embodiments, the circulating water after heat exchange with the high-temperature molten salt exchanges heat with the feedwater output from the coal-fired power unit through a feedwater heater.

[0012] In some embodiments, the feedwater output from the coal-fired power unit comes from the feedwater inlet and outlet of the high-pressure heater in the coal-fired power unit.

[0013] According to the second aspect of this application, a full-load denitrification method based on molten salt thermal storage is proposed, which utilizes the full-load denitrification system in any of the above embodiments to perform peak shaving for coal-fired power units, including the following operating conditions:

[0014] During peak shaving by coal-fired power units: Low-temperature molten salt transported from the molten salt cold tank to the molten salt hot tank exchanges heat with the steam output from the coal-fired power unit in the steam condenser to form high-temperature molten salt, which is stored in the molten salt hot tank; Part of the high-temperature molten salt in the molten salt hot tank exchanges heat with the circulating flue gas of the denitrification system through a second heat exchange element to maintain the optimal temperature of the flue gas at the inlet of the denitrification system;

[0015] When the coal-fired power unit is not in peak shaving mode: part of the high-temperature molten salt in the molten salt hot tank exchanges heat with the circulating water output from the coal-fired power unit through the first heat exchange element, so as to cool the high-temperature molten salt and increase the temperature of the circulating water.

[0016] In some embodiments, when the reading of the flue gas thermometer is higher than a set value, the circulating flue gas in the flue gas circuit is reduced; when the reading of the flue gas thermometer is lower than the set value, the circulating flue gas in the flue gas circuit is increased.

[0017] In some embodiments, when the level gauge reading of the cold tank is lower than the lower limit, the molten salt cold tank stops outputting low-temperature molten salt; when the level gauge reading of the cold tank exceeds the upper limit, the molten salt hot tank stops outputting high-temperature molten salt.

[0018] When the level gauge reading in the hot tank is lower than the alarm value, the hot molten salt tank stops outputting high-temperature molten salt; when the level gauge reading in the hot tank exceeds the alarm value, the cold molten salt tank stops outputting low-temperature molten salt.

[0019] Compared with existing technologies, this application has the following advantages:

[0020] This application utilizes a molten salt thermal storage unit to store and utilize heat in coal-fired power units, thereby improving the flexibility of these units. Simultaneously, this application uses the heat stored in the molten salt to increase the inlet flue gas temperature of the denitrification device through flue gas recirculation, which can be used during deep peak shaving or startup of the unit to achieve full-load denitrification of the unit.

[0021] 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

[0022] 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:

[0023] Figure 1 This is a schematic diagram of the full-load denitrification system based on molten salt thermal storage proposed in one embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the full-load denitrification system based on molten salt thermal storage proposed in one embodiment of this application;

[0025] Figure 3 This is a flowchart of a full-load denitrification method based on molten salt thermal storage proposed in another embodiment of this application;

[0026] In the diagram: 1. Molten salt cold tank; 2. Molten salt pump for cold tank; 3. Steam condenser; 4. Molten salt hot tank; 5. Molten salt pump for hot tank; 6. Circulating water heater; 7. Flue gas heater; 8. Cold tank level gauge; 9. Hot tank level gauge; 10. Steam pipeline; 11. Condensate pipeline; 12. Steam electric switch valve; 13. Condensate electric switch valve; 14. Feedwater heater; 15. Circulating water pump; 16. No. 3 high-pressure heater; 17. No. 2 high-pressure heater; 8. No. 1 high-pressure heater; 19. Inlet water pipe; 20. Outlet water pipe; 21. Main electric regulating valve; 22. First electric switch valve; 23. Second electric switch valve; 24. Economizer; 25. Denitrification device; 26. Air preheater; 27. Dust collector; 28. Exhaust fan; 29. ​​Desulfurization tower; 30. First flue; 31. Second flue; 32. Flue gas regulating valve; 33. Flue gas shut-off valve; 34. Flue gas thermometer; 35. Water thermometer. Detailed Implementation

[0027] Embodiments of this application are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0028] To achieve the above objectives, such as Figure 1 According to the first aspect of this application, a full-load denitrification system based on molten salt thermal storage is proposed, which includes a molten salt thermal storage unit connected to the denitrification system of a coal-fired power unit for heat exchange; the molten salt thermal storage unit includes a molten salt circulation loop composed of a molten salt cold tank 1, a steam condenser 3, a molten salt hot tank, and a heat exchange component; wherein the heat exchange component includes a first heat exchange element and a second heat exchange element; during peak shaving of the coal-fired power unit, the low-temperature molten salt in the molten salt circulation loop exchanges heat with the steam output from the coal-fired power unit through the steam condenser 3 and generates high-temperature molten salt, and the high-temperature molten salt exchanges heat with the circulating flue gas of the denitrification system through the second heat exchange element to maintain the optimal temperature of the flue gas at the inlet of the denitrification system.

[0029] In this embodiment, the molten salt thermal storage unit includes a molten salt circulation loop consisting of a molten salt cold tank 1, a steam condenser 3, a molten salt hot tank 4, and heat exchange components. Both the molten salt cold tank 1 and the molten salt hot tank 4 are formed from insulated profiles of a certain volume, and each includes a molten salt inlet and a molten salt outlet. The molten salt outlet of the molten salt cold tank 1 is connected to the cold side inlet of the steam condenser 3, and the cold side outlet of the steam condenser 3 is connected to the molten salt inlet of the molten salt hot tank 4. The low-temperature molten salt output from the molten salt cold tank 1 can be heated by introducing a heat exchange medium through the hot side of the steam condenser 3.

[0030] A cold tank molten salt pump 2 and a hot tank molten salt pump 5 are installed in the molten salt circulation loop; the cold tank molten salt pump 2 and the hot tank molten salt pump 5 are used to pump the low-temperature molten salt output from the cold tank 1 and the high-temperature molten salt output from the hot tank 4. For example... Figure 1 As shown, the cold tank molten salt pump 2 is located at the molten salt outlet of the molten salt cold tank 1, and the hot tank molten salt pump 5 is located at the molten salt outlet of the molten salt hot tank 4.

[0031] In this embodiment, the low-temperature molten salt in the molten salt circulation loop exchanges heat with the steam output from the coal-fired power unit through the steam condenser 3 to generate high-temperature molten salt. In other words, the hot side of the steam condenser 3 is supplied with steam output from the coal-fired power unit to heat the low-temperature molten salt output from the molten salt cold tank 1. Figure 1As shown, the steam output from the coal-fired power unit is drawn from the outlet of each stage of the superheater or the inlet or outlet of each stage of the reheater. A steam pipe 10 is installed at the hot-side inlet of the steam condenser 3, and a condensate pipe 11 is installed at its hot-side outlet. The condensate pipe 11 connects to the deaerator or condenser hot well of the coal-fired power unit. A steam electric switch valve 12 is installed on the steam pipe 10, and a condensate electric switch valve 13 is installed on the condensate pipe 11. The steam electric switch valve 12 and the condensate electric switch valve 13 can adjust the steam flow rate on the hot side of the steam condenser 3, thereby controlling the heat exchange temperature of the low-temperature molten salt on the cold side of the steam condenser 3 and outputting the high-temperature molten salt to the molten salt hot tank 4. A portion of the high-temperature molten salt in the molten salt hot tank 4 is connected to the hot-side inlet of the heat exchange assembly through the molten salt outlet of the molten salt hot tank 4. After heat exchange between the molten salt in the heat exchange assembly and the medium on the cold side of the heat exchange assembly, it is connected to the molten salt inlet of the molten salt cold tank 1 through the hot-side outlet of the heat exchange assembly, forming a molten salt circulation loop.

[0032] In this embodiment, the heat exchange assembly includes a first heat exchanger and a second heat exchanger. During peak shaving of the coal-fired power unit, a portion of the high-temperature molten salt in the molten salt heat tank 4 exchanges heat with the circulating flue gas of the denitrification system through the second heat exchanger to maintain the optimal temperature of the flue gas at the inlet of the denitrification system. In other words, along the flow direction of the flue gas, the denitrification system includes an economizer 24, a denitrification device 25, an air preheater 26, a dust collector 27, an induced draft fan 28, and a desulfurization tower 29 connected upstream and downstream. Specifically, in this application, a flue gas circuit is provided between the outlet of the induced draft fan 28 and the inlet of the denitrification device 25, and the second heat exchanger is provided on the flue gas circuit.

[0033] like Figure 2 As shown, the first heat exchanger can be a circulating water heater 6, and the second heat exchanger can be a flue gas heater 7. Both the first and second heat exchangers include a hot side and a cold side that exchange heat but are not interconnected. The hot side of the first heat exchanger is connected to the hot side of the second heat exchanger. The high-temperature molten salt output from the molten salt heater passes sequentially through the hot side of the first heat exchanger and the hot side of the second heat exchanger. When the coal-fired power unit is shaving its peak load, no heat exchange medium is introduced into the cold side of the first heat exchanger, while the circulating flue gas output from the outlet of the induced draft fan 28 is introduced into the hot side of the second heat exchanger. The circulating flue gas is heated by the high-temperature molten salt, and the heated circulating flue gas is then introduced into the inlet of the denitrification device 25 to maintain the optimal temperature of the flue gas at the inlet of the denitrification system.

[0034] In some embodiments, a flue gas thermometer 34 is provided at the inlet of the denitrification device 25.

[0035] The denitrification device 25 is equipped with a flue gas thermometer 34 at its inlet. The flue gas circuit includes a first flue 30 and a second flue 31. The inlet of the first flue 30 is connected to the flue between the induced draft fan 28 and the desulfurization tower 29, and its outlet is connected to the cold side inlet of the flue gas heater 7. The inlet of the second flue 31 is connected to the cold side outlet of the flue gas heater 7, and its outlet is connected to the flue between the economizer 24 and the denitrification device 25. A flue gas regulating valve 32 is arranged on the first flue 30, and a flue gas shut-off valve 33 is arranged on the second flue 31.

[0036] The flue gas thermometer 34 is configured to display the temperature of the hot flue gas entering the denitrification device 25. This temperature, when set, represents the optimal operating temperature window for the denitrification device 25. In this application, the opening degree of the flue gas regulating valve 32 is correlated with the reading of the flue gas thermometer 34. When the reading is higher than the set value, the opening degree of the flue gas regulating valve 32 is decreased; when the reading is lower than the set value, the opening degree of the flue gas regulating valve 32 is increased.

[0037] In some embodiments, both the molten salt cold tank 1 and the molten salt hot tank are equipped with a cold tank level gauge 8 and a hot tank level gauge 9.

[0038] In this application, both the molten salt cold tank 1 and the molten salt hot tank are equipped with a cold tank level gauge 8 and a hot tank level gauge 9. As their names suggest, the cold tank level gauge 8 and the hot tank level gauge 9 are used to measure the level of molten salt in the molten salt cold tank 1 and the molten salt hot tank, respectively. When the reading of the cold tank level gauge 8 is lower than the lower limit, the cold tank molten salt pump 2 is automatically shut down via an interlock. When the reading of the cold tank level gauge 8 exceeds the upper limit, the hot tank molten salt pump 5 is automatically shut down via an interlock. When the reading of the hot tank level gauge 9 is lower than the alarm value, the hot tank molten salt pump 5 is automatically shut down via an interlock. When the reading of the hot tank level gauge 9 exceeds the alarm value, the cold tank molten salt pump 2 is automatically shut down via an interlock.

[0039] In some embodiments, the high-temperature molten salt exchanges heat with the circulating water output from the coal-fired power unit through a first heat exchanger to cool the high-temperature molten salt.

[0040] During non-peak season operation of the coal-fired power unit, high-temperature molten salt in the molten salt hot tank enters the hot side of the first heat exchanger via the hot tank molten salt pump 5, and exchanges heat with the circulating water on the cold side of the first heat exchanger to cool the high-temperature molten salt. The circulating water output from the coal-fired power unit is cooling water connected to the inlet and outlet circulation pipelines on the cold side of the first heat exchanger. The water circulation pipelines are connected to the feedwater heater 14 and the circulating water pump 15. The feedwater heater 14 includes a hot side and a cold side for heat exchange but not interconnection. The circulating water is on the hot side of the feedwater heater 14. The circulating water pump 15 provides power for the circulation of the circulating water. To ensure that the temperature of the circulating water can be continuously cooled, the circulating water after heat exchange with the high-temperature molten salt exchanges heat with the feedwater output from the coal-fired power unit through the feedwater heater 14.

[0041] The cold side of the feedwater heater 14 receives feedwater from the coal-fired power unit. In some embodiments, the feedwater output from the coal-fired power unit comes from the feedwater at the inlet and outlet of the high-pressure heater in the coal-fired power unit. For example... Figure 2 The coal-fired power unit also includes a No. 3 high-pressure heater 16, a No. 2 high-pressure heater 17, a No. 1 high-pressure heater 18, and a feedwater heater 14, connected in sequence, with an inlet pipe 19 and an outlet pipe 20. The branch pipe of the inlet pipe 19 is connected to the inlet and outlet of the No. 2 high-pressure heater 17, respectively. A main electric regulating valve 21 is installed on the branch pipe connected to the inlet of the No. 2 high-pressure heater 17, a first electric switch valve 22 is installed on the inlet pipe 19, and a second electric switch valve 23 is installed on the outlet pipe 20. At the same time, a water thermometer 35 is installed on the outlet pipe 20 of the feedwater heater 14.

[0042] During non-peak season operation of the coal-fired power unit: Molten salt in the molten salt hot tank 4 is pumped by the hot tank molten salt pump 5 through the hot side of the circulating water heater 6, and exchanges heat with the circulating water on the cold side of the circulating water heater 6. The low-temperature molten salt after heat exchange enters the molten salt cold tank 1. The opening degree of the main electric regulating valve 21 is linked to the reading of the water thermometer 35. When the reading is lower than the set value, the opening degree of the main electric regulating valve 21 is reduced; when the reading is higher than the set value, the opening degree of the main electric regulating valve 21 is increased. The set value of the water thermometer 35 must ensure that the economizer 24 does not vaporize.

[0043] According to the second aspect of this application, a full-load denitrification method based on molten salt thermal storage is proposed, such as... Figure 3 Using the full-load denitrification system in any of the above embodiments to perform peak shaving for coal-fired power units includes the following operating conditions:

[0044] During peak shaving of coal-fired power units: the low-temperature molten salt from the molten salt cold tank 1 is transported to the molten salt hot tank and exchanges heat with the steam output from the coal-fired power unit in the steam condenser 3 to form high-temperature molten salt, which is stored in the molten salt hot tank; part of the high-temperature molten salt in the molten salt hot tank exchanges heat with the circulating flue gas of the denitrification system through the second heat exchange element to maintain the optimal temperature of the flue gas at the inlet of the denitrification system.

[0045] During non-peak shaving operations of coal-fired power units: some of the high-temperature molten salt in the molten salt hot tank exchanges heat with the circulating water output from the coal-fired power unit through the first heat exchange element to cool the high-temperature molten salt and increase the temperature of the circulating water.

[0046] In some embodiments, when the reading of the flue gas thermometer 34 is higher than the set value, the circulating flue gas in the flue gas circuit is reduced; when the reading of the flue gas thermometer 34 is lower than the set value, the circulating flue gas in the flue gas circuit is increased.

[0047] In some embodiments, when the reading of the cold tank level gauge 8 is lower than the lower limit, the molten salt cold tank 1 stops outputting low-temperature molten salt; when the reading of the cold tank level gauge 8 exceeds the upper limit, the molten salt hot tank stops outputting high-temperature molten salt.

[0048] When the reading of the hot tank level gauge 9 is lower than the alarm value, the hot molten salt tank stops outputting high-temperature molten salt; when the reading of the hot tank level gauge 9 exceeds the alarm value, the cold molten salt tank 1 stops outputting low-temperature molten salt.

[0049] During peak shaving of coal-fired power units, the steam electric switch valve 12 and condensate electric switch valve 13 are opened, the cold tank molten salt pump 2 and the hot tank molten salt pump 5 are opened, the circulating water pump 15 is closed, the flue gas regulating valve 32 and the flue gas shut-off valve 33 are opened, and the main electric regulating valve 21, the first electric switch valve 22, and the second electric switch valve 23 are closed. Molten salt in the cold tank 1 is heated by the steam condenser 3 via the cold tank molten salt pump 2 and then enters the hot tank 4. Molten salt in the hot tank 4 is cooled by the flue gas heater 7 via the hot tank molten salt pump 5 and then enters the cold tank 1. The opening degree of the flue gas regulating valve 32 is linked to the reading of the flue gas thermometer 34. When the reading is higher than the set value, the opening degree of the flue gas regulating valve 32 is reduced; when the reading is lower than the set value, the opening degree of the flue gas regulating valve 32 is increased. The set value is the optimal operating temperature window of the denitrification device 25.

[0050] During non-peak season operation of the coal-fired power unit, the steam electric switch valve 12 and condensate electric switch valve 13 are closed, the cold tank molten salt pump 2 is shut down, the hot tank molten salt pump 5 is started, the circulating water pump 15 is started, the flue gas regulating valve 32 and the flue gas shut-off valve 33 are closed, and the main electric regulating valve 21, the first electric switch valve 22, and the second electric switch valve 23 are opened. Molten salt in the hot tank 4 is cooled by the flue gas heater 7 after passing through the hot tank molten salt pump 5 and then enters the cold tank 1. The opening degree of the main electric regulating valve 21 is correlated with the reading of the water thermometer 35. When the reading is lower than the set value, the opening degree of the main electric regulating valve 21 is decreased; when the reading is higher than the set value, the opening degree of the main electric regulating valve 21 is increased. In addition, during peak shaving or non-peak shaving, when the level gauge 8 of the cold tank is lower than the lower limit, the molten salt pump 2 of the cold tank will be automatically shut down by interlock; when the level gauge 8 of the cold tank is higher than the upper limit, the molten salt pump 5 of the hot tank will be automatically shut down by interlock; when the level gauge 9 of the hot tank is lower than the alarm value, the molten salt pump 5 of the hot tank will be automatically shut down by interlock; when the level gauge 9 of the hot tank is higher than the alarm value, the molten salt pump 2 of the cold tank will be automatically shut down by interlock.

[0051] Therefore, in this application, during peak shaving of coal-fired power units, the high-temperature steam heat of the coal-fired power units is stored to improve the flexibility of the coal-fired power units, and the flue gas recirculation is used to increase the inlet flue gas temperature of the denitrification device 25 to achieve full-load denitrification; during non-peak shaving of coal-fired power units, the stored heat is released to heat the feedwater, reduce steam extraction, and increase the work done by the coal-fired power units.

[0052] In the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0053] 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 more executable instructions for implementing a particular logical function or process, 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 function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0054] 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.

[0055] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A full-load denitrification system based on molten salt thermal storage, characterized in that, It includes a molten salt thermal storage unit that is connected to the denitrification system of a coal-fired power unit for heat exchange; The molten salt thermal storage unit includes a molten salt circulation loop consisting of a molten salt cold tank, a steam condenser, a molten salt hot tank, and a heat exchange assembly. The heat exchange assembly includes a first heat exchanger and a second heat exchanger. During peak shaving of the coal-fired power unit, the low-temperature molten salt in the molten salt circulation loop exchanges heat with the steam output from the coal-fired power unit through the steam condenser to generate high-temperature molten salt. The high-temperature molten salt exchanges heat with the circulating flue gas of the denitrification system through the second heat exchanger to maintain the optimal temperature of the flue gas at the inlet of the denitrification system.

2. The full-load denitrification system according to claim 1, characterized in that, Along the flow direction of the flue gas, the denitrification system includes an economizer, a denitrification device, an air preheater, a dust collector, an induced draft fan, and a desulfurization tower connected upstream and downstream; and a flue gas circuit is provided between the outlet of the induced draft fan and the inlet of the denitrification device, and the second heat exchanger is provided on the flue gas circuit.

3. The full-load denitrification system according to claim 2, characterized in that, A flue gas thermometer is installed at the inlet of the denitrification device.

4. The full-load denitrification system according to any one of claims 1-3, characterized in that, Both the molten salt cold tank and the molten salt hot tank are equipped with cold tank level gauges and hot tank level gauges.

5. The full-load denitrification system according to claim 4, characterized in that, The high-temperature molten salt exchanges heat with the circulating water output from the coal-fired power unit through the first heat exchanger to cool the high-temperature molten salt.

6. The full-load denitrification system according to claim 4, characterized in that, The circulating water, after exchanging heat with the high-temperature molten salt, exchanges heat with the feedwater output from the coal-fired power unit through a feedwater heater.

7. The full-load denitrification system according to claim 6, characterized in that, The feedwater output from the coal-fired power unit comes from the feedwater at the inlet and outlet of the high-pressure heater in the coal-fired power unit.

8. A full-load denitrification method based on molten salt thermal storage, characterized in that, Peak shaving of coal-fired power units using the full-load denitrification system described in any one of claims 1-7 includes the following operating conditions: During peak shaving by coal-fired power units: Low-temperature molten salt transported from the molten salt cold tank to the molten salt hot tank exchanges heat with the steam output from the coal-fired power unit in the steam condenser to form high-temperature molten salt, which is stored in the molten salt hot tank; Part of the high-temperature molten salt in the molten salt hot tank exchanges heat with the circulating flue gas of the denitrification system through a second heat exchange element to maintain the optimal temperature of the flue gas at the inlet of the denitrification system; When the coal-fired power unit is not in peak shaving mode: part of the high-temperature molten salt in the molten salt hot tank exchanges heat with the circulating water output from the coal-fired power unit through the first heat exchange element, so as to cool the high-temperature molten salt and increase the temperature of the circulating water.

9. The method according to claim 8, characterized in that, When the reading of the flue gas thermometer is higher than the set value, the circulating flue gas in the flue gas circuit is reduced; when the reading of the flue gas thermometer is lower than the set value, the circulating flue gas in the flue gas circuit is increased.

10. The method according to claim 8, characterized in that, When the level gauge reading in the cold tank is below the lower limit, the molten salt cold tank stops outputting low-temperature molten salt; when the level gauge reading in the cold tank exceeds the upper limit, the molten salt hot tank stops outputting high-temperature molten salt. When the level gauge reading in the hot tank is lower than the alarm value, the hot molten salt tank stops outputting high-temperature molten salt; when the level gauge reading in the hot tank exceeds the alarm value, the cold molten salt tank stops outputting low-temperature molten salt.

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