Thermoelectric decoupling system of secondary reheating unit and heat supply method of secondary reheating unit

Abstract

The invention provides a thermoelectric decoupling system of a secondary reheating unit and a heat supply method of the secondary reheating unit, and belongs to the field of heat supply of thermal generator sets. The system comprises a first pressure matcher, a second pressure matcher and a third pressure matcher, the driving end of the first pressure matcher is connected with the first output end of a main steam pipeline of the secondary reheating unit, the injection end of the first pressure matcher is connected with the steam exhaust end of an ultrahigh pressure cylinder, and the driving end of the second pressure matcher is connected with the steam output end of a primary reheater. The injection end is connected with the steam exhaust end of the high-pressure cylinder. The driving end of the third pressure matcher is connected with the steam output end of the secondary reheater, the injection end of the third pressure matcher is connected with the first steam exhaust end of the intermediate-pressure cylinder, and the pressure matcher is connected with different steam extraction points of the secondary reheating unit so that different steam of the secondary reheating unit can be mixed to obtain wide-range heat supply steam parameters, the pressure of output steam can be flexibly controlled, and the heat supply efficiency can be improved. Therefore, flexible heat supply to high-pressure industrial users, medium-pressure industrial users and low-pressure industrial users is achieved.

Description

Technical Field

[0001] The invention relates to the field of heating of thermal power generating sets, and in particular to a thermoelectric decoupling system of a secondary reheating set and a heating method of the secondary reheating set. Background Art

[0002] With the development of new power systems, heating units are required to have not only stable heating capacity, but also good peak load regulation and peak performance to meet the needs of the power system. However, most existing heating units have the same boiler output configuration and cannot flexibly respond to heating needs under different working conditions, which not only leads to low thermal efficiency and energy waste, but also affects the stability and reliability of the power system.

[0003] Especially for units with large heating capacity, the heat load is large during the winter heating period, and the peak-shaving capacity of the unit is limited, making it difficult to meet the peak-shaving demand of the power system; during the peak period of the power system, the peak capacity of the unit is insufficient, affecting the stability of the power system; under deep peak-shaving conditions, the steam extraction volume and steam extraction pressure are insufficient to meet the heating demand.

[0004] Existing technologies can improve the peak load and peak load capacity of heating units by optimizing the operation strategies of heating units, such as adjusting the start and stop time and load distribution of the units; however, this method is limited by the performance of the units themselves and external conditions, and the effect is limited. Alternatively, the peak load capacity of the units can be improved by adding energy storage devices, such as battery energy storage and supercapacitor energy storage, to the heating units. However, this method is costly, and there are also certain problems with the life and reliability of the energy storage devices. Summary of the invention

[0005] In order to solve the above-mentioned technical defects, the present invention provides a thermoelectric decoupling system of a secondary reheat unit and a heating method of a secondary reheat unit, wherein the thermoelectric decoupling system of the secondary reheat unit is provided with multiple pressure matchers, and the multiple pressure matchers are connected to different steam extraction points of the secondary reheat unit to mix different steams of the secondary reheat unit to obtain a wide range of heating steam parameters, thereby realizing flexible control of the pressure of the output steam; the steam with different steam parameters provided by the pressure matcher and the steam with different steam parameters provided by the ultra-high pressure cylinder, high pressure cylinder, medium pressure cylinder and low pressure cylinder of the secondary reheat unit, the thermoelectric decoupling system of the secondary reheat unit can flexibly provide heating for high-pressure industrial users, medium-pressure industrial users, low-pressure industrial users and heating users.

[0006] The first aspect of the present invention provides a thermoelectric decoupling system of a secondary reheat unit, the secondary reheat unit comprising: an ultra-high pressure cylinder, a high pressure cylinder, an intermediate pressure cylinder, a low pressure cylinder, a main steam pipeline, a primary reheater and a secondary reheater, the steam input end of the primary reheater is connected to the first exhaust end of the ultra-high pressure cylinder, the steam output end of the primary reheater is connected to the reheat steam input end of the high pressure cylinder; the steam input end of the secondary reheater is connected to the first exhaust end of the high pressure cylinder, the steam output end of the secondary reheater is connected to the reheat steam input end of the intermediate pressure cylinder, the thermoelectric decoupling system comprises: a pressure matcher module; The pressure matcher module comprises: a first pressure matcher, a second pressure matcher and a third pressure matcher, wherein the driving end of the first pressure matcher is connected to the first output end of the main steam pipeline, the ejector end of the first pressure matcher is connected to the first exhaust end of the ultra-high pressure cylinder, the driving end of the second pressure matcher is connected to the steam output end of the primary reheater, the ejector end of the second pressure matcher is connected to the exhaust end of the high pressure cylinder, the driving end of the third pressure matcher is connected to the steam output end of the secondary reheater, and the ejector end of the third pressure matcher is connected to the first exhaust end of the intermediate pressure cylinder; The second output end of the main steam pipeline, the output end of the first pressure matcher or the second exhaust end of the ultra-high pressure cylinder is used to supply heat to high-pressure industrial users; The second exhaust end of the ultra-high pressure cylinder, the second exhaust end of the high pressure cylinder or the output end of the second pressure matcher is used to supply heat to medium pressure industrial users; The second exhaust end of the high-pressure cylinder or the output end of the third pressure matcher is used to supply heat to low-pressure industrial users; The second exhaust end of the medium-pressure cylinder or the exhaust end of the low-pressure cylinder is used to supply heat to heating users.

[0007] In an embodiment of the present invention, the primary reheater comprises: a high-pressure and high-temperature reheater, a high-pressure and low-temperature reheater, and a primary reheat steam pipeline; The high-pressure and high-temperature reheater is arranged in the horizontal flue of the secondary reheat unit; The high-pressure and low-temperature reheater is arranged in the tail flue of the secondary reheat unit; The input end of the primary reheat steam pipeline is connected to the output end of the high-pressure and high-temperature reheater, and the output end of the primary reheat steam pipeline is connected to the reheat steam input end of the high-pressure cylinder.

[0008] In an embodiment of the present invention, the secondary reheater comprises: a low-pressure high-temperature reheater, a low-pressure low-temperature reheater and a secondary reheat steam pipeline; The low-pressure and high-temperature reheater is arranged in the horizontal flue of the secondary reheat unit; The low-pressure and low-temperature reheater is arranged in the tail flue of the secondary reheat unit; The input end of the secondary reheat steam pipeline is connected to the output end of the low-pressure and high-temperature reheater, and the output end of the secondary reheat steam pipeline is connected to the reheat steam input end of the intermediate-pressure cylinder.

[0009] In an embodiment of the present invention, the high-pressure and high-temperature reheater, the high-pressure and low-temperature reheater, the low-pressure and high-temperature reheater, and the low-pressure and low-temperature reheater are all convection heating surfaces.

[0010] In this embodiment, the thermoelectric decoupling system also includes: a flue gas regulating baffle, which is arranged at the end of the tail flue of the secondary reheat unit, and the flue gas regulating baffle is used to adjust the heat exchange amount of the heating surfaces of the high-pressure and high-temperature reheater, the high-pressure and low-temperature reheater, the low-pressure and high-temperature reheater, and the low-pressure and low-temperature reheater.

[0011] In the embodiment of the present invention, a first butterfly valve is installed on the connecting pipe between the second exhaust end of the medium pressure cylinder and the heating user; A second butterfly valve is installed on the connecting pipe between the exhaust end of the low-pressure cylinder and the heating user.

[0012] In an embodiment of the present invention, the thermoelectric decoupling system further comprises: a flue gas recirculation bypass, wherein the flue gas recirculation bypass comprises: a recirculation duct and a circulation fan; The input end of the recirculation pipeline is connected to the outlet end of the tail flue of the secondary reheat unit, and the output end of the recirculation pipeline is connected to the combustion place of the furnace of the secondary reheat unit, so as to send the treated flue gas into the furnace.

[0013] In an embodiment of the present invention, the thermoelectric decoupling system further includes: a swing burner, wherein the swing burner is disposed inside the furnace, and the swing burner is used to change the position of the combustion center area of ​​the furnace.

[0014] A second aspect of the present invention provides a heating method for a secondary reheat unit, which is applied to the thermoelectric decoupling system of the secondary reheat unit as described above, and the method comprises: The output of the secondary reheat unit is configured according to a preset electric load capacity, wherein the preset electric load capacity is determined by the electric load capacity demand; When the secondary reheat unit is in full load operation, heat is supplied to high-pressure industrial users through the second exhaust end of the ultra-high-pressure cylinder, heat is supplied to medium-pressure industrial users through the second exhaust end of the high-pressure cylinder, heat is supplied to low-pressure industrial users through the output end of the third pressure matcher, and heat is supplied to heating users through the exhaust end of the low-pressure cylinder; When the secondary reheat unit is in deep peak-shaving operation, heat is supplied to high-pressure industrial users through the second output end of the main steam pipeline, heat is supplied to medium-pressure industrial users through the second exhaust end of the ultra-high-pressure cylinder, heat is supplied to low-pressure industrial users through the second exhaust end of the high-pressure cylinder, and heat is supplied to heating users through the second exhaust end of the medium-pressure cylinder and the exhaust end of the low-pressure cylinder; When the secondary reheat unit is operating under normal load conditions, heat is supplied to high-pressure industrial users through the output end of the first pressure matcher, heat is supplied to medium-pressure industrial users through the output end of the second pressure matcher, heat is supplied to low-pressure industrial users through the output end of the third pressure matcher, and heat is supplied to heating users through the second exhaust end of the medium-pressure cylinder and the exhaust end of the low-pressure cylinder.

[0015] In an embodiment of the present invention, the method further includes: When the user heating demand of the secondary reheat unit increases, the opening of the flue gas regulating damper of the thermoelectric decoupling system is increased to increase the heat exchange of the heating surfaces of the primary reheater and the secondary reheater; When the user heating demand of the secondary reheat unit decreases, the heat exchange amount of the heating surfaces of the primary reheater and the secondary reheater is reduced by reducing the opening of the flue gas regulating damper of the thermoelectric decoupling system.

[0016] In an embodiment of the present invention, the method further includes: When the user heating demand of the secondary reheat unit increases, the heat exchange between the heating surfaces of the primary reheater and the secondary reheater is increased by increasing the flue gas recirculation volume in the flue gas recirculation bypass of the thermoelectric decoupling system; When the user heating demand of the secondary reheat unit decreases, the heat exchange amount of the heating surfaces of the primary reheater and the secondary reheater is reduced by reducing the flue gas recirculation amount in the flue gas recirculation bypass of the thermoelectric decoupling system. The thermoelectric decoupling system of the secondary reheat unit is provided with multiple pressure matchers, and the multiple pressure matchers are connected to different steam extraction points of the secondary reheat unit to mix different steams of the secondary reheat unit to obtain a wide range of heating steam parameters, thereby realizing flexible control of the pressure of the output steam; the steam with different steam parameters provided by the pressure matchers and the steam with different steam parameters provided by the ultra-high pressure cylinder, high pressure cylinder, medium pressure cylinder and low pressure cylinder of the secondary reheat unit, the thermoelectric decoupling system of the secondary reheat unit can flexibly provide heating for high-pressure industrial users, medium-pressure industrial users, low-pressure industrial users and heating users.

[0017] Other features and advantages of the technical solution of the present invention will be described in detail in the specific implementation section below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a structural schematic diagram of a thermoelectric decoupling system of a secondary reheat unit provided in an embodiment of the present invention.

[0019] Description of Reference Numerals 1-first stage superheater, 2-rear screen superheater, 3-final stage superheater, 4-high pressure and high temperature reheater, 5-low pressure and high temperature reheater, 6-high pressure and low temperature reheater, 7-low pressure and low temperature reheater, 8-second stage economizer, 9-rear flue gas adjustment damper, 10-circulation fan, 11-flue gas recirculation nozzle, 12-swinging burner, 13-ultra-high pressure cylinder, 14-high pressure cylinder, 15-medium pressure cylinder, 16-low pressure cylinder, 17-generator, 18-regulating valve, 19-first pressure matcher 20-first butterfly valve, 2 1-check valve, 22-second output end of the main steam pipeline, 23-output end of the first pressure matcher, 24-first exhaust end of the ultra-high pressure cylinder, 25-second exhaust end of the ultra-high pressure cylinder, 26-second exhaust end of the high pressure cylinder, 27-first exhaust end of the high pressure cylinder, 28-output end of the second pressure matcher, 29-output end of the third pressure matcher, 30-second exhaust end of the medium pressure cylinder, 31-exhaust end of the low pressure cylinder, 32-second pressure matcher, 33-third pressure matcher, 34-second butterfly valve. DETAILED DESCRIPTION

[0020] In order to make the technical solutions and advantages of the embodiments of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the process of realizing the present invention, the inventors found that with the development of new power systems, heating units are required to have not only stable heating capacity, but also good peak load regulation and peak performance to meet the needs of the power system. However, most existing heating units have the same boiler output configuration and cannot flexibly respond to heating needs under different working conditions, which not only leads to low thermal efficiency and energy waste, but also affects the stability and reliability of the power system.

[0025] Especially for units with large heating capacity, the heat load is large during the winter heating period, and the peak-shaving capacity of the unit is limited, making it difficult to meet the peak-shaving demand of the power system; during the peak period of the power system, the peak capacity of the unit is insufficient, affecting the stability of the power system; under deep peak-shaving conditions, the steam extraction volume and steam extraction pressure are insufficient to meet the heating demand.

[0026] Existing technologies can improve the peak load and peak load capacity of heating units by optimizing the operation strategies of heating units, such as adjusting the start and stop time and load distribution of the units; however, this method is limited by the performance of the units themselves and external conditions, and the effect is limited. Alternatively, the peak load capacity of the units can be improved by adding energy storage devices, such as battery energy storage and supercapacitor energy storage, to the heating units. However, this method is costly, and there are also certain problems with the life and reliability of the energy storage devices.

[0027] In view of the above problems, an embodiment of the present invention provides a thermoelectric decoupling system of a secondary reheat unit, wherein the secondary reheat unit comprises: an ultra-high pressure cylinder, a high pressure cylinder, an intermediate pressure cylinder, a low pressure cylinder, a main steam pipeline, a primary reheater and a secondary reheater, wherein the steam input end of the primary reheater is connected to the first exhaust end of the ultra-high pressure cylinder, and the steam output end of the primary reheater is connected to the reheat steam input end of the high pressure cylinder; the steam input end of the secondary reheater is connected to the first exhaust end of the high pressure cylinder, and the steam output end of the secondary reheater is connected to the reheat steam input end of the intermediate pressure cylinder, and the thermoelectric decoupling system comprises: a pressure matcher module; the pressure matcher module comprises: a first pressure matcher, a second pressure matcher and a third pressure matcher, wherein the driving end of the first pressure matcher is connected to the first output end of the main steam pipeline, and the first The ejector end of the pressure matcher is connected to the first exhaust end of the ultra-high pressure cylinder, the driving end of the second pressure matcher is connected to the steam output end of the primary reheater, the ejector end of the second pressure matcher is connected to the exhaust end of the high pressure cylinder, the driving end of the third pressure matcher is connected to the steam output end of the secondary reheater, and the ejector end of the third pressure matcher is connected to the first exhaust end of the medium pressure cylinder; the second output end of the main steam pipeline, the output end of the first pressure matcher or the second exhaust end of the ultra-high pressure cylinder is used to supply heat to high-pressure industrial users, the second exhaust end of the ultra-high pressure cylinder, the second exhaust end of the high pressure cylinder or the output end of the second pressure matcher is used to supply heat to medium-pressure industrial users, the second exhaust end of the high pressure cylinder or the output end of the third pressure matcher is used to supply heat to low-pressure industrial users, and the second exhaust end of the medium pressure cylinder or the exhaust end of the low pressure cylinder is used to supply heat to heating users. The thermoelectric decoupling system of the secondary reheat unit is provided with multiple pressure matchers, and the multiple pressure matchers are connected to different steam extraction points of the secondary reheat unit to mix different steams of the secondary reheat unit to obtain a wide range of heating steam parameters, thereby realizing flexible control of the pressure of the output steam; the steam with different steam parameters provided by the pressure matchers and the steam with different steam parameters provided by the ultra-high pressure cylinder, high pressure cylinder, medium pressure cylinder and low pressure cylinder of the secondary reheat unit, the thermoelectric decoupling system of the secondary reheat unit can flexibly provide heating for high-pressure industrial users, medium-pressure industrial users, low-pressure industrial users and heating users.

[0028] Figure 1 Schematic diagram of the structure of the thermoelectric decoupling system of the secondary reheat unit provided in the embodiment of the present invention. Figure 1As shown, the present embodiment provides a thermoelectric decoupling system of a secondary reheat unit, wherein the secondary reheat unit comprises: a furnace, a superheater, an ultra-high pressure cylinder 13, a high pressure cylinder 14, an intermediate pressure cylinder 15, a low pressure cylinder 16, a main steam pipeline, a primary reheater, a secondary reheater, a horizontal flue, a tail flue and a generator 17, wherein the steam input end of the primary reheater is connected to the first exhaust end 24 of the ultra-high pressure cylinder, and the steam output end of the primary reheater is connected to the reheat steam input end of the high pressure cylinder 14; the steam input end of the secondary reheater is connected to the first exhaust end 27 of the high pressure cylinder, and the steam output end of the secondary reheater is connected to the reheat steam input end of the intermediate pressure cylinder 15.

[0029] Among them, the primary reheater includes: a high-pressure and high-temperature reheater 4, a high-pressure and low-temperature reheater 6 and a primary reheat steam pipeline, and the secondary reheater includes: a low-pressure and high-temperature reheater 5, a low-pressure and low-temperature reheater 7 and a secondary reheat steam pipeline. The high-pressure and high-temperature reheater 4 and the low-pressure and high-temperature reheater 5 are arranged in the horizontal flue, and the high-pressure and low-temperature reheater 6 and the low-pressure and low-temperature reheater 7 are arranged in the tail flue. The input end of the primary reheat steam pipeline is connected to the output end of the high-pressure and high-temperature reheater 4, and the output end of the primary reheat steam pipeline is connected to the reheat steam input end of the high-pressure cylinder 14. ; The input end of the secondary reheat steam pipeline is connected to the output end of the low-pressure and high-temperature reheater 5, and the output end of the secondary reheat steam pipeline is connected to the reheat steam input end of the medium-pressure cylinder 15.

[0030] The superheater includes: a first-stage superheater 1, a rear-screen superheater 2 and a final-stage superheater 3 connected in sequence. The main steam output by the final-stage superheater 3 is input into the first pressure matcher 19 through the first output end of the main steam pipeline, and serves as the driving steam source of the first pressure matcher 19. The main steam is transported to the ultra-high pressure cylinder 13 through the second output end 22 of the main steam pipeline. The main steam enters the ultra-high pressure cylinder 13 to do work, and generates exhaust steam of the ultra-high pressure cylinder 13 after doing work.

[0031] The exhaust steam from the first exhaust end 24 of the ultra-high pressure cylinder is sequentially heat exchanged through the high pressure low temperature reheater 6 and the high pressure high temperature reheater 4 to obtain primary reheat steam. The primary reheat steam is input to the reheat steam input end of the high pressure cylinder 14 through the primary reheat steam pipeline, and the primary reheat steam enters the high pressure cylinder 14 to perform work, and after performing work, the exhaust steam of the high pressure cylinder 14 is generated.

[0032] The exhaust steam from the first exhaust end 27 of the high pressure cylinder passes through the low pressure low temperature reheater 7 and the low pressure high temperature reheater 5 for heat exchange to obtain secondary reheat steam. The secondary reheat steam is input to the reheat steam input end of the intermediate pressure cylinder 15 through the secondary reheat steam pipeline, and the secondary reheat steam enters the intermediate pressure cylinder 15 to perform work, and generates exhaust steam of the intermediate pressure cylinder 15 after performing work.

[0033] The thermoelectric decoupling system includes: a pressure matching module; the pressure matching module includes: a first pressure matching device 19, a second pressure matching device 32 and a third pressure matching device 33. The driving end of the first pressure matching device 19 is connected to the first output end of the main steam pipeline of the secondary reheat unit, the ejection end of the first pressure matching device 19 is connected to the first exhaust end 24 of the ultra-high pressure cylinder, the driving end of the second pressure matching device 32 is connected to the steam output end of the primary reheater, the ejection end of the second pressure matching device 32 is connected to the exhaust end of the high pressure cylinder 14, the driving end of the third pressure matching device 33 is connected to the steam output end of the secondary reheater, and the ejection end of the third pressure matching device 33 is connected to the first exhaust end of the medium pressure cylinder 15; the first pressure matching device 19, the second pressure matching device 32 and the third pressure matching device 33 can fully utilize the energy of the high pressure fluid and reduce energy waste by ejecting low pressure fluid. At the same time, it can realize the effective matching of fluids of different pressure levels and improve the energy utilization efficiency of the system. The pressure matcher in the present invention can accurately adjust the ratio of high-pressure fluid to low-pressure fluid according to the needs of the system, thereby realizing flexible control of the output pressure. The use of the pressure matcher can balance the pressure difference between different pressure sources, reduce the impact of pressure fluctuations in the system, and make the heating unit more stable and reliable during operation.

[0034] The second output end 22 of the main steam pipe of the secondary reheat unit, the output end 23 of the first pressure matcher or the second exhaust end 25 of the ultra-high pressure cylinder is used to supply heat to high-pressure industrial users, the second exhaust end 25 of the ultra-high pressure cylinder, the second exhaust end 26 of the high-pressure cylinder or the output end 28 of the second pressure matcher is used to supply heat to medium-pressure industrial users, the second exhaust end 26 of the high-pressure cylinder or the output end 29 of the third pressure matcher is used to supply heat to low-pressure industrial users, and the second exhaust end 30 of the medium-pressure cylinder or the exhaust end 31 of the low-pressure cylinder is used to supply heat to heating users.

[0035] Specifically, when the secondary reheat unit is in full load operation, heat is supplied to high-pressure industrial users through the second exhaust end 25 of the ultra-high-pressure cylinder, heat is supplied to medium-pressure industrial users through the second exhaust end 26 of the high-pressure cylinder, heat is supplied to low-pressure industrial users through the output end 29 of the third pressure matcher, and heat is supplied to heating users through the exhaust end 31 of the low-pressure cylinder; When the secondary reheat unit is in deep peak load regulation operation, heat is supplied to high-pressure industrial users through the second output end 22 of the main steam pipeline, heat is supplied to medium-pressure industrial users through the second exhaust end 25 of the ultra-high-pressure cylinder, heat is supplied to low-pressure industrial users through the second exhaust end 26 of the high-pressure cylinder, and heat is supplied to heating users through the second exhaust end 30 of the medium-pressure cylinder and the exhaust end 31 of the low-pressure cylinder; When the secondary reheat unit is operating under normal load conditions, heat is supplied to high-pressure industrial users through the output end 23 of the first pressure matcher, heat is supplied to medium-pressure industrial users through the output end 28 of the second pressure matcher, heat is supplied to low-pressure industrial users through the output end 29 of the third pressure matcher, and heat is supplied to heating users through the second exhaust end 30 of the medium-pressure cylinder and the exhaust end 31 of the low-pressure cylinder.

[0036] As the unit load decreases, the high-pressure extraction point gradually moves towards the main steam, the medium-pressure extraction point moves towards the ultra-high-pressure exhaust steam, and the low-pressure extraction point moves towards the high-pressure exhaust steam, achieving flexible application and switching under different load conditions.

[0037] The thermoelectric decoupling system of the secondary reheat unit proposed in the present invention is provided with multiple pressure matchers, and the multiple pressure matchers are connected to different steam extraction points of the secondary reheat unit to mix different steams of the secondary reheat unit to obtain a wide range of heating steam parameters, thereby realizing flexible control of the pressure of the output steam; the steam with different steam parameters provided by the pressure matchers and the steam with different steam parameters provided by the ultra-high pressure cylinder 13, high pressure cylinder 14, medium pressure cylinder 15 and low pressure cylinder 16 of the secondary reheat unit, the thermoelectric decoupling system of the secondary reheat unit can flexibly provide heat for high-pressure industrial users, medium-pressure industrial users, low-pressure industrial users and heating users.

[0038] Furthermore, the high-pressure and high-temperature reheater 4, the high-pressure and low-temperature reheater 6, the low-pressure and high-temperature reheater 5, and the low-pressure and low-temperature reheater 7 are all convection heating surfaces. The high-pressure and high-temperature reheater 4 and the high-pressure and low-temperature reheater 6 are arranged in the horizontal flue and the tail flue, and the exhaust steam of the super-high-pressure cylinder 13 is heated for the high-pressure cylinder 14 to do work, which is a primary reheating. The low-pressure and high-temperature reheater 5 and the low-pressure and low-temperature reheater 7 are arranged in the horizontal flue and the tail flue, and the exhaust steam of the high-pressure cylinder 14 is heated for the medium-pressure cylinder 15 to do work, which is a secondary reheating. The reheaters arranged in the horizontal flue and the tail flue are all convection heating surfaces. More convection heating surfaces enable the system to respond more quickly to changes in heating demand. When the heating demand increases, the system can transfer heat to the heating medium more quickly to improve the heating capacity; when the heating demand decreases, the system can also adjust the heat output more quickly to avoid energy waste. Different users may have different demands for heating, such as different requirements for temperature, pressure, etc. Adding a convective heat exchange surface can make the system better adapt to these diverse needs and meet the specific heating requirements of different users by flexibly adjusting the working state of the heat exchange surface.

[0039] Furthermore, the furnace is also provided with a first-stage superheater 1, a rear screen superheater 2 and a final superheater 3. The heating surfaces of the first-stage superheater 1, the rear screen superheater 2 and the final superheater 3 are full radiation heating surfaces. The flame temperature and radiation intensity of the combustion process are the main factors affecting the heating conditions of the radiation heating surfaces. The high-pressure and high-temperature reheater 4, the high-pressure and low-temperature reheater 6, the low-pressure and low-temperature reheater 7 and the low-pressure and high-temperature reheater 5 arranged in the horizontal flue and the tail flue are all convection heating surfaces. The flue gas flow rate and temperature are the main factors affecting the heating conditions of the convection heating surfaces. The advantage of setting the reheater as a convection heating surface is that it can enable the system to respond more quickly to changes in heating demand. When the heating demand increases, the heat can be transferred to the heating medium more quickly to improve the heating capacity; and when the heating demand decreases, the heat output can be adjusted in time to avoid energy waste. In addition, more convection heat exchange surfaces can better meet the diverse heating needs of different users, such as different requirements in temperature and pressure. By flexibly adjusting the working state of the heat exchange surface, the specific heating needs of different users can be accurately met.

[0040] The thermoelectric decoupling system also includes: a flue gas regulating damper, which is arranged at the end of the tail flue of the secondary reheat unit, and is used to adjust the heat exchange of the heating surfaces of the high-pressure and high-temperature reheater 4, the high-pressure and low-temperature reheater 6, the low-pressure and high-temperature reheater 5 and the low-pressure and low-temperature reheater 7. Specifically, the present invention arranges a flue gas regulating damper in the tail flue, and connects it to the control system. Under the conditions of unit load changes, changes in steam extraction conditions, etc., the flue gas damper can respond quickly, accurately adjust the opening of the flue gas damper to control the flue gas flow, thereby adjusting the heat exchange of each heating surface, so that the heat can be used more effectively and improve energy utilization efficiency. In addition, under conditions such as mismatched steam extraction, by adjusting the opening of the flue gas damper, the heat of the flue gas flowing to certain heating surfaces can be reduced, preventing the temperature of the heating surface from being too high, avoiding the occurrence of over-temperature problems, and ensuring the safe operation of the unit. Furthermore, the flue gas regulating damper is arranged at the outlet of the secondary economizer 8 of the secondary reheat unit and the end of the flue at the rear of the boiler. After the flue gas flows out of the reheater, it passes through the secondary economizer, SCR denitrification, primary economizer, air preheater, etc. in sequence. The flue gas regulating damper is arranged at the outlet of the secondary economizer 8 and the end of the flue at the rear of the boiler, and is closely connected with the control system. When the load of the unit changes or the steam extraction condition changes, the flue gas regulating damper can respond quickly and control the flue gas flow by accurately adjusting its opening, thereby realizing the regulation of the heat exchange of each heating surface, making the heat more efficiently utilized and improving the energy utilization efficiency. Under special conditions such as the mismatch of steam extraction, adjusting the opening of the flue gas regulating damper can reduce the flue gas heat flowing to certain heating surfaces, effectively preventing the heating surface temperature from being too high, avoiding over-temperature problems, and providing a solid guarantee for the safe operation of the unit.

[0041] In this embodiment, a first butterfly valve 20 is installed on the connection pipe between the second exhaust end 30 of the medium-pressure cylinder and the heating user; a second butterfly valve 34 is installed on the connection pipe between the exhaust end 31 of the low-pressure cylinder and the heating user. Specifically, the present invention sets butterfly valves on the exhaust pipes of the medium and low-pressure cylinders 16, and changes the flow resistance of steam in the medium and low-pressure cylinders 16 by adjusting the opening of the butterfly valves of the medium and low-pressure cylinders 16 and adopting the pressure-holding mode of the butterfly valves of the medium and low-pressure cylinders 16, thereby realizing the control of the pressure. By reasonably controlling the opening of the butterfly valves, the pressure can be adjusted according to actual needs to meet the heating requirements under different working conditions. By holding the pressure, the pressure and temperature of the steam can be increased, thereby improving the heating efficiency, which helps to provide more heat under the same energy consumption and meet the heating needs of users. The pressure-holding mode of the butterfly valves of the medium and low-pressure cylinders 16 helps to achieve thermoelectric decoupling. By independently adjusting the opening of the butterfly valves, the heating needs can be met without affecting power generation, thereby improving the flexibility and adaptability of the system.

[0042] In this embodiment, the thermoelectric decoupling system further includes: a flue gas recirculation bypass, which includes: a recirculation pipe and a circulation fan 10; the input end of the recirculation pipe is connected to the outlet end of the tail flue of the secondary reheat unit, and the output end of the recirculation pipe is connected to the combustion place of the furnace of the secondary reheat unit, which is used to send the treated flue gas into the furnace. Specifically, the circulation fan 10 sends a part of the flue gas in the outlet flue of the secondary economizer 8 of the unit into the furnace through the flue gas recirculation nozzle 11, thereby changing the total amount of flue gas in the furnace and the convection heating surface, and changing the heat absorption of the convection heating surface by changing the recirculation flue gas flow rate to adjust the steam temperature. According to the layout characteristics of the heating surface in the furnace, the first-stage superheater 1, the rear screen superheater 2, and the final superheater 3 use radiation heating surfaces, and the flue gas recirculation mainly affects the heat exchange of the high and low pressure high temperature reheaters 5 arranged in the horizontal flue and the high and low pressure low temperature reheaters 7 in the tail flue. By flexibly adjusting the flue gas recirculation volume, we can better adapt to changes in unit load and external conditions, and improve the system's regulation ability and adaptability.

[0043] Furthermore, the input end of the recirculation pipeline is arranged on the pipeline between the boiler tail flue and the SCR denitrification equipment.

[0044] In this embodiment, the thermoelectric decoupling system also includes: a swinging burner 12, the swinging burner 12 is arranged inside the furnace, and the swinging burner 12 is used to change the combustion center area of ​​the furnace. The swinging burner 12 includes a primary air nozzle and a secondary air nozzle. The secondary air nozzle can swing up and down 30° each, and the primary air nozzle can swing up and down 20° each, so as to change the position of the combustion center area, adjust the heat absorption of each radiation heating surface in the furnace, and then accurately control the reheat steam temperature in different links. By adjusting the reheater steam temperature, the needs of different users for heating steam parameters can be flexibly met. Changing the reheater steam temperature can be used as a means of regulation to help achieve thermoelectric decoupling.

[0045] Before the system is put into operation, operation debugging is carried out to ensure the coordinated control of various equipment in the system. In combination with the needs of the power grid and the needs of industrial steam users, the operating conditions of various equipment are adjusted to ensure that the operation of various equipment can be closely coordinated and coordinated. For example, when the unit is in a high-load operation state, the boiler output is appropriately increased, and the opening of the tail flue gas regulating damper 9 is reasonably adjusted, the output of the circulating fan 10 is increased, the combustion angle of the swing burner 12 is optimized, the fluid ratio of the pressure matcher is accurately controlled, and the opening of the butterfly valve is appropriately adjusted to ensure that various equipment work together and operate efficiently, so as to achieve reasonable distribution and effective utilization of heat and meet the capacity requirements under high load to the greatest extent; and when the unit is in a peak-shaving operation state, the boiler output is correspondingly reduced, and the control parameters of each equipment are finely adjusted to achieve thermal and electrical decoupling, flexibly adapt to load changes, and meet peak-shaving needs.

[0046] When the unit is officially in operation, the thermoelectric decoupling system accurately determines the current load condition by real-time monitoring of the medium parameters of each heating surface of the boiler, the grid-side demand and the demand of industrial steam users. Subsequently, the control parameters of the equipment such as the boiler output, the tail flue gas regulating damper 9, the circulating fan 10, the swing burner 12, multiple pressure matchers and multiple butterfly valves are dynamically adjusted according to the load conditions. In this process, achieving the best thermoelectric decoupling effect and energy utilization efficiency is the key goal. For example, when operating at full load, increase the boiler output and optimize the parameters of each device to ensure sufficient heat absorption and efficient combustion; when operating at deep peak load, reasonably adjust the equipment parameters to meet the heating demand and achieve thermoelectric decoupling. At the same time, ensuring the safe operation of the unit is also an important consideration. For example, when the temperature of a certain heating surface is detected to be too high, the intelligent control system will automatically reduce the opening of the flue gas regulating damper in the area or increase the proportion of flue gas recirculation to reduce the temperature of the heating surface and avoid the occurrence of overheating. After completing the above installation and settings, debug the intelligent control system.

[0047] The heating method of the secondary reheat unit provided in this embodiment is applied to the thermoelectric decoupling system of the secondary reheat unit as described above, and the method comprises: The output of the secondary reheat unit is configured according to a preset electric load capacity, wherein the preset electric load capacity is determined by the electric load capacity demand; When the secondary reheat unit is in full load operation, heat is supplied to high-pressure industrial users through the second exhaust end 25 of the ultra-high-pressure cylinder, heat is supplied to medium-pressure industrial users through the second exhaust end 26 of the high-pressure cylinder, heat is supplied to low-pressure industrial users through the output end 29 of the third pressure matcher, heat is supplied to heating users through the exhaust end 31 of the low-pressure cylinder, and heating steam is supplied to the second exhaust end 30 of the medium-pressure cylinder; When the secondary reheat unit is in deep peak load regulation operation, heat is supplied to high-pressure industrial users through the second output end 22 of the main steam pipeline, heat is supplied to medium-pressure industrial users through the second exhaust end 25 of the ultra-high-pressure cylinder, heat is supplied to low-pressure industrial users through the second exhaust end 26 of the high-pressure cylinder, and heat is supplied to heating users through the second exhaust end 30 of the medium-pressure cylinder and the exhaust end 31 of the low-pressure cylinder; When the secondary reheat unit is operating under normal load conditions, heat is supplied to high-pressure industrial users through the output end 23 of the first pressure matcher, heat is supplied to medium-pressure industrial users through the output end 28 of the second pressure matcher, heat is supplied to low-pressure industrial users through the output end 29 of the third pressure matcher, and heat is supplied to heating users through the second exhaust end 30 of the medium-pressure cylinder and the exhaust end 31 of the low-pressure cylinder.

[0048] Specifically, multiple branches are opened in the main steam pipeline and the exhaust pipes of each cylinder of the turbine, and the branches are connected by pressure matchers. Regulating valves 18, butterfly valves, and check valves 21 are set on different branch pipe sections to coordinate and control the unit in full load operation, 20% deep peak regulation operation, and conventional load operation to provide different heating modes for high-pressure industrial users (10MPa\400℃), medium-pressure industrial users (3.5MPa\440℃), low-pressure industrial users (1.5MPa\420℃), and heating users (0.4MPa\330℃).

[0049] For example: under full-load operating condition (I), the ultra-high pressure cylinder 13 is used to exhaust steam for high-pressure users, the high-pressure cylinder 14 is used to exhaust steam for medium-pressure users, a third pressure matcher 33 is added to use secondary reheat hot resteam exhaust to inject steam into the medium-pressure cylinder 15 to exhaust steam for low-pressure users, the low-pressure cylinder 16 is used to exhaust steam for heating, and the second exhaust end 30 of the medium-pressure cylinder is used to supply steam for heating.

[0050] Under the 20% deep peak load regulation operation condition (II), the main steam is desuperheated to directly supply high-pressure users, the ultra-high-pressure cylinder 13 exhaust steam is used to supply medium-pressure users, the high-pressure cylinder 14 exhaust steam is used to supply low-pressure users, and the medium and low-pressure cylinders 16 butterfly valve pressure holding method is used to supply heating to residents.

[0051] Under the normal load operation condition (III), the main steam is used to draw the extra-high pressure cylinder 13 exhaust steam through the first pressure matcher 19 to supply high-pressure users, the first reheat hot resteam is used to draw the high-pressure cylinder 14 exhaust steam through the second pressure matcher 32 to supply medium-pressure users, the second reheat hot resteam is used to draw the medium-pressure cylinder 15 exhaust steam to supply low-pressure users, and the medium and low pressure cylinders 16 are used to provide heating for residents by holding the pressure with butterfly valves.

[0052] The pressure matcher can fully utilize the energy of high-pressure fluid and reduce energy waste by injecting low-pressure fluid. At the same time, it can achieve effective matching of fluids of different pressure levels and improve the energy efficiency of the system. A pressure matcher is added to the steam turbine exhaust pipe. The pressure matcher can accurately adjust the ratio of high-pressure fluid and low-pressure fluid according to the needs of the system, thereby achieving flexible control of the output pressure, reducing the impact of pressure fluctuations in the system, and making the heating unit more stable and reliable during operation.

[0053] In this embodiment, the method further includes: When the user's heating demand of the secondary reheat unit increases, the opening of the flue gas regulating damper is increased to increase the heat exchange of the heating surfaces of the primary reheater and the secondary reheater; When the user heating demand of the secondary reheat unit decreases, the heat exchange amount of the heating surfaces of the primary reheater and the secondary reheater is reduced by reducing the opening of the flue gas regulating damper.

[0054] The flue gas regulating damper is arranged in the tail flue. By connecting it to the control system, the flue gas damper can respond quickly to changes in unit load and steam extraction conditions, and accurately adjust the opening of the flue gas damper to control the flue gas flow, thereby adjusting the heat exchange of each heating surface, so that the heat can be used more effectively and improve energy utilization efficiency. In addition, under conditions such as mismatch in steam extraction, by adjusting the opening of the flue gas damper, the flue gas heat flowing to certain heating surfaces can be reduced, preventing the heating surface temperature from being too high, avoiding the occurrence of over-temperature problems, and ensuring the safe operation of the unit.

[0055] In this embodiment, the method further includes: When the user heating demand of the secondary reheat unit increases, the heat exchange between the heating surfaces of the primary reheater and the secondary reheater is increased by increasing the flue gas recirculation volume in the flue gas recirculation bypass; When the user heating demand of the secondary reheat unit decreases, the heat exchange amount of the heating surfaces of the primary reheater and the secondary reheater is reduced by reducing the flue gas recirculation amount in the flue gas recirculation bypass.

[0056] The circulating fan 10 delivers part of the flue gas in the outlet flue of the secondary economizer 8 of the unit into the furnace through the flue gas recirculation nozzle 11, thereby changing the total amount of flue gas in the furnace and the convection heating surface. By changing the recirculating flue gas flow rate, the heat absorption of the convection heating surface is changed to adjust the steam temperature. According to the layout characteristics of the heating surface in the furnace, the first-stage superheater 1, the rear screen superheater 2, and the final superheater 3 use radiation heating surfaces. The flue gas recirculation mainly affects the heat exchange of the high and low pressure high temperature reheaters 5 arranged in the horizontal flue and the high and low pressure low temperature reheaters 7 in the tail flue. By flexibly adjusting the flue gas recirculation volume, it is possible to better adapt to changes in unit load and external conditions, and improve the adjustment ability and adaptability of the system.

[0057] In this embodiment, the method further includes: When the heating demand of the user of the secondary reheat unit changes, the reheat air temperature is changed by adjusting the nozzle angle of the swing burner 12. By adjusting the reheater steam temperature, the requirements of different users for heating steam parameters can be flexibly met. Changing the reheater steam temperature can be used as a means of regulation to help achieve thermal and electrical decoupling.

[0058] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0059] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0060] The optional implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings. However, the implementation modes of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the implementation modes of the present invention, a variety of simple modifications can be made to the technical solutions of the implementation modes of the present invention, and these simple modifications all belong to the protection scope of the implementation modes of the present invention. It should also be noted that the various specific technical features described in the above specific implementation modes can be combined in any suitable manner without contradiction, and as long as the combination does not violate the concept of the implementation modes of the present invention, it should also be regarded as the content disclosed in the implementation modes of the present invention.

Claims

1. A thermoelectric decoupling system for a secondary reheat unit, the secondary reheat unit comprising: The ultra-high pressure cylinder, the high pressure cylinder, the medium pressure cylinder, the low pressure cylinder, the main steam pipeline, the primary reheater and the secondary reheater are characterized in that the thermoelectric decoupling system comprises: a pressure matcher module; The pressure matcher module comprises: a first pressure matcher, a second pressure matcher and a third pressure matcher, wherein the driving end of the first pressure matcher is connected to the first output end of the main steam pipeline, the ejector end of the first pressure matcher is connected to the first exhaust end of the ultra-high pressure cylinder, the driving end of the second pressure matcher is connected to the steam output end of the primary reheater, the ejector end of the second pressure matcher is connected to the exhaust end of the high pressure cylinder, the driving end of the third pressure matcher is connected to the steam output end of the secondary reheater, and the ejector end of the third pressure matcher is connected to the first exhaust end of the intermediate pressure cylinder; The second output end of the main steam pipeline, the output end of the first pressure matcher or the second exhaust end of the ultra-high pressure cylinder is used to supply heat to high-pressure industrial users; The second exhaust end of the ultra-high pressure cylinder, the second exhaust end of the high pressure cylinder or the output end of the second pressure matcher is used to supply heat to medium pressure industrial users; The second exhaust end of the high-pressure cylinder or the output end of the third pressure matcher is used to supply heat to low-pressure industrial users; The second exhaust end of the medium-pressure cylinder or the exhaust end of the low-pressure cylinder is used to supply heat to heating users.

2. The thermoelectric decoupling system of the secondary reheat unit according to claim 1, characterized in that: The primary reheater comprises: a high-pressure and high-temperature reheater, a high-pressure and low-temperature reheater and a primary reheat steam pipeline; The high-pressure and high-temperature reheater is arranged in the horizontal flue of the secondary reheat unit; The high-pressure and low-temperature reheater is arranged in the tail flue of the secondary reheat unit; The input end of the primary reheat steam pipeline is connected to the output end of the high-pressure and high-temperature reheater, and the output end of the primary reheat steam pipeline is connected to the reheat steam input end of the high-pressure cylinder; the secondary reheater includes: a low-pressure and high-temperature reheater, a low-pressure and low-temperature reheater, and a secondary reheat steam pipeline; The horizontal flue of the low-pressure high-temperature reheater secondary reheat unit; The low-pressure and low-temperature reheater is arranged in the tail flue of the secondary reheat unit; The input end of the secondary reheat steam pipeline is connected to the output end of the low-pressure and high-temperature reheater, and the output end of the secondary reheat steam pipeline is connected to the reheat steam input end of the intermediate-pressure cylinder.

3. The thermoelectric decoupling system of the secondary reheat unit according to claim 2, characterized in that: The high-pressure and high-temperature reheater, the high-pressure and low-temperature reheater, the low-pressure and high-temperature reheater and the low-pressure and low-temperature reheater are all convection heating surfaces.

4. The thermoelectric decoupling system of the secondary reheat unit according to claim 3, characterized in that: The thermoelectric decoupling system also includes: a flue gas regulating baffle, which is arranged at the end of the tail flue of the secondary reheat unit, and the flue gas regulating baffle is used to adjust the heat exchange of the heating surfaces of the high-pressure and high-temperature reheater, the high-pressure and low-temperature reheater, the low-pressure and high-temperature reheater, and the low-pressure and low-temperature reheater.

5. The thermoelectric decoupling system of the secondary reheat unit according to claim 1, characterized in that: A first butterfly valve is installed on the connecting pipe between the second exhaust end of the medium pressure cylinder and the heating user; A second butterfly valve is installed on the connecting pipe between the exhaust end of the low-pressure cylinder and the heating user.

6. The thermoelectric decoupling system of the secondary reheat unit according to claim 1, characterized in that: The thermoelectric decoupling system further comprises: a flue gas recirculation bypass, wherein the flue gas recirculation bypass comprises: a recirculation duct and a circulation fan; The input end of the recirculation pipeline is connected to the outlet end of the tail flue of the secondary reheat unit, and the output end of the recirculation pipeline is connected to the combustion place of the furnace of the secondary reheat unit, so as to send the treated flue gas into the furnace.

7. The thermoelectric decoupling system of the secondary reheat unit according to claim 1, characterized in that: The thermoelectric decoupling system further includes: a swing burner, which is arranged inside the furnace of the secondary reheat unit and is used to change the position of the combustion center area of ​​the furnace.

8. A heating method for a secondary reheat unit, applied to a thermoelectric decoupling system of a secondary reheat unit according to any one of claims 1 to 7, characterized in that: The method comprises: The output of the secondary reheat unit is configured according to a preset electric load capacity, wherein the preset electric load capacity is determined by the electric load capacity demand; When the secondary reheat unit is in full load operation, heat is supplied to high-pressure industrial users through the second exhaust end of the ultra-high-pressure cylinder, heat is supplied to medium-pressure industrial users through the second exhaust end of the high-pressure cylinder, heat is supplied to low-pressure industrial users through the output end of the third pressure matcher, and heat is supplied to heating users through the exhaust end of the low-pressure cylinder; When the secondary reheat unit is in deep peak-shaving operation, heat is supplied to high-pressure industrial users through the second output end of the main steam pipeline, heat is supplied to medium-pressure industrial users through the second exhaust end of the ultra-high-pressure cylinder, heat is supplied to low-pressure industrial users through the second exhaust end of the high-pressure cylinder, and heat is supplied to heating users through the second exhaust end of the medium-pressure cylinder and the exhaust end of the low-pressure cylinder; When the secondary reheat unit is operating under normal load conditions, heat is supplied to high-pressure industrial users through the output end of the first pressure matcher, heat is supplied to medium-pressure industrial users through the output end of the second pressure matcher, heat is supplied to low-pressure industrial users through the output end of the third pressure matcher, and heat is supplied to heating users through the second exhaust end of the medium-pressure cylinder and the exhaust end of the low-pressure cylinder.

9. The heating method of the secondary reheat unit according to claim 8, characterized in that: The method further comprises: When the user heating demand of the secondary reheat unit increases, the opening of the flue gas regulating damper of the thermoelectric decoupling system is increased to increase the heat exchange of the heating surfaces of the primary reheater and the secondary reheater; When the user heating demand of the secondary reheat unit decreases, the heat exchange amount of the heating surfaces of the primary reheater and the secondary reheater is reduced by reducing the opening of the flue gas regulating damper of the thermoelectric decoupling system.

10. The heating method of the secondary reheat unit according to claim 8, characterized in that: The method further comprises: When the user heating demand of the secondary reheat unit increases, the heat exchange between the heating surfaces of the primary reheater and the secondary reheater is increased by increasing the flue gas recirculation volume in the flue gas recirculation bypass of the thermoelectric decoupling system; When the user heating demand of the secondary reheat unit decreases, the heat exchange amount of the heating surfaces of the primary reheater and the secondary reheater is reduced by reducing the flue gas recirculation amount in the flue gas recirculation bypass of the thermoelectric decoupling system.

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