A secondary reheat unit system and an operation method thereof

Abstract

The present invention relates to the technical field of peak shaving for secondary reheat units, and particularly relates to a secondary reheat unit system and an operation method. The secondary reheat unit system includes: a steam turbine unit, the steam inlet end of which is connected to a steam generator, and the steam outlet end of which is connected to a regenerative heater. A condenser is connected between the steam outlet end of the steam turbine unit and the regenerative heater; a heat exchanger, one end of the first flow channel of which is connected between the steam turbine unit and the steam generator, and the other end of which is connected to the condenser; a condensate regulating valve is installed at one end of the first flow channel connected to the condenser, and a reheated steam regulating valve is installed at the other end; an energy storage assembly, which is connected to the second flow channel of the heat exchanger. By setting up the heat exchanger and the energy storage assembly, and cooperating with the condensate regulating valve and the reheated steam regulating valve to perform variable load operation peak shaving on the secondary reheat unit system, it is possible to eliminate the limitation of the variable load rate of the unit caused by inertia difference and accelerate the peak shaving rate of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of peak shaving of secondary reheat units, and particularly relates to a secondary reheat unit system and an operation method thereof. Background Art

[0002] In the context of large-scale grid connection of renewable energy, coal-fired units are transformed from the main energy source to a regulating support energy source. To adapt to the intermittent characteristics of renewable energy, coal-fired units face frequent and rapid peak shaving processes. Secondary reheat units are typical advanced and efficient coal-fired units, and improving their flexibility is of great significance for building a new power system.

[0003] Compared with primary reheat units, the secondary reheat units in the prior art need to add a super high-pressure cylinder, a secondary reheater and corresponding control mechanisms, making the unit structure, regulation and operation more complex, resulting in an increase in the inertia difference between the boiler system and the steam turbine system, and restricting the peak shaving ability of the secondary reheat units. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the load change rate of secondary reheat units is limited due to the inertia difference in the prior art, so as to provide a secondary reheat unit system and an operation method thereof.

[0005] To solve the above technical problem, the present invention provides a secondary reheat unit system, including:

[0006] A steam turbine unit, the steam inlet end of which is connected to a steam generator, the steam outlet end of which is connected to a regenerative heater, and a condenser is connected between the steam outlet end of the steam turbine unit and the regenerative heater;

[0007] A heat exchanger, one end of the first flow channel of which is connected between the steam turbine unit and the steam generator, and the other end is connected to the condenser; a condensate regulating valve is installed at the end of the first flow channel connected to the condenser, and a reheated steam regulating valve is installed at the other end;

[0008] An energy storage assembly, which is connected to the second flow channel of the heat exchanger.

[0009] Optionally, the energy storage assembly includes a heat storage component and a cold storage component, and the heat storage component and the cold storage component are respectively connected to both ends of the second flow channel.

[0010] Optionally, a high-temperature medium regulating valve is installed between the heat storage component and the second flow channel; a low-temperature medium regulating valve is installed between the cold storage component and the second flow channel.

[0011] Optionally, the steam turbine unit includes a super high-pressure cylinder, a normal high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder, the super high-pressure cylinder, the normal high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder are respectively connected to the regenerative heater, and the condenser is installed between the low-pressure cylinder and the regenerative heater.

[0012] Optionally, the steam generator includes a three-stage heating flow path. Among them, the inlet end of the first-stage heating flow path is connected to the regenerative heater, and the outlet end is connected to the ultra-high pressure cylinder; the inlet end of the second-stage heating flow path is connected to the ultra-high pressure cylinder, and the outlet end is connected to the high pressure cylinder; the inlet of the third-stage heating flow path is connected to the high pressure cylinder, and the outlet end is connected to the intermediate pressure cylinder, and the outlet end of the intermediate pressure cylinder is connected to the low pressure cylinder; the first flow path is connected between the ultra-high pressure cylinder and the second-stage heating flow path.

[0013] Optionally, a generator is installed on the output shaft of the steam turbine unit.

[0014] The present invention also provides an operation method for a secondary reheat unit, which is applied to the secondary reheat unit system described in the present invention, and includes the following steps:

[0015] When the secondary reheat unit system is operating at a reduced load, adjust the reheat steam regulating valve to extract the reheat steam in the regenerative heater to release heat in the first flow path of the heat exchanger, and the reheat steam after heat release flows into the condenser;

[0016] The energy storage component controls the low-temperature medium to enter the second flow path of the heat exchanger to absorb heat;

[0017] The opening of the reheat steam regulating valve is adjusted according to the following formula:

[0018]

[0019] In the above formula: ΔG 15 is the extraction amount of the primary cold reheat steam set according to the load change rate and the load change range, with the unit of kg / s; Δp 15 is the difference between the reheat steam pressure and the pressure at the heat exchanger, with the unit of MPa; ρ 15 is the density of the reheat steam, with the unit of kg / m 3 ; K v,15 is the resistance gain coefficient of the reheat steam regulating valve.

[0020] Optionally, it further includes:

[0021] When the secondary reheat unit system is operating at an increased load, the energy storage component controls the high-temperature medium to enter the second flow path of the heat exchanger to release heat;

[0022] Adjust the condensate regulating valve to extract the condensate to the first flow path of the heat exchanger to absorb heat, and the condensate after heat absorption enters the steam generator;

[0023] The opening of the condensate regulating valve is adjusted according to the following formula:

[0024]

[0025] In the above formula, ΔG 16is the condensate extraction flow rate set according to the variable load rate and variable load range, with the unit of kg / s; Δp 16 is the pressure difference between the condenser and the heat exchanger, with the unit of MPa; ρ 16 is the condensate density, with the unit of kg / m 3 ; K v,16 is the resistance gain coefficient of the condensate regulating valve.

[0026] Optionally, it further includes: when the secondary reheat unit system is operating at a reduced load, the opening degree of the low-temperature medium regulating valve is adjusted according to the following formula:

[0027]

[0028] In the above formula: h rh is the enthalpy value of the reheated steam, with the unit of kJ / kg; h c is the enthalpy value of the condensate, with the unit of kJ / kg; h cr is the enthalpy value of the high-temperature heat storage medium, with the unit of kJ / kg; h cc is the enthalpy value of the low-temperature heat storage medium, with the unit of kJ / kg; Δp6 is the pressure difference between the cold storage part and the heat exchanger, with the unit of MPa; ρ6 is the low-temperature medium density, with the unit of kg / m 3 ; K v,6 is the resistance gain coefficient of the low-temperature medium regulating valve.

[0029] Optionally, it further includes: when the secondary reheat unit system is operating at an increased load, the opening degree of the high-temperature medium regulating valve is adjusted according to the following formula:

[0030]

[0031] In the above formula: h rh is the enthalpy value of the reheated steam, with the unit of kJ / kg; h c is the enthalpy value of the condensate, with the unit of kJ / kg; h cr is the enthalpy value of the high-temperature heat storage medium, with the unit of kJ / kg; h cc is the enthalpy value of the low-temperature heat storage medium, with the unit of kJ / kg; Δp2 is the pressure difference between the heat storage part and the heat exchanger, with the unit of MPa; ρ2 is the low-temperature medium density, with the unit of kg / m 3 ; K v,2 is the resistance gain coefficient of the high-temperature medium regulating valve.

[0032] The technical solution of the present invention has the following advantages:

[0033] 1. The secondary reheat unit system provided by the present invention includes: a steam turbine unit, the steam inlet end of which is connected to a steam generator, and the steam outlet end of which is connected to a regenerative heater. A condenser is connected between the steam outlet end of the steam turbine unit and the regenerative heater; a heat exchanger, one end of the first flow channel of which is connected between the steam turbine unit and the steam generator, and the other end of which is connected to the condenser; a condensate regulating valve is installed at one end of the first flow channel connected to the condenser, and a reheated steam regulating valve is installed at the other end; an energy storage assembly, which is connected to the second flow channel of the heat exchanger.

[0034] When the secondary reheat unit system performs peak shaving during variable load operation, during the load reduction process, under the existing control strategy, the reheated steam is prone to under-temperature. When the secondary reheat unit system provided by the present invention operates at reduced load, the reheated steam regulating valve is opened to extract a part of the reheated steam, which enters the heat exchanger for heat exchange, and its heat is stored in the energy storage assembly; during the load increase process, under the existing control strategy, the reheated steam is prone to over-temperature. When the secondary reheat unit system provided by the present invention operates at increased load, the condensate regulating valve is opened to extract a part of the condensate, which enters the heat exchanger for heat exchange, is heated to the temperature of the primary cold reheated steam and then sent to the steam generator for heat exchange. During the load reduction operation, the flow rate of the reheated steam is reduced, which can alleviate the phenomenon of under-temperature of the reheated steam, and then the amount of steam entering the steam turbine unit for work is reduced, and the work done is reduced, accelerating the load reduction rate of the unit. During the load increase operation, the flow rate of the reheated steam is increased, which can alleviate the phenomenon of over-temperature of the reheated steam, improve the safety during the operation process, and the amount of steam entering the steam turbine for work is increased, and the work done is increased, accelerating the load increase rate of the unit. By setting the heat exchanger and the energy storage assembly, and cooperating with the condensate regulating valve and the reheated steam regulating valve to perform peak shaving for the secondary reheat unit system during variable load operation, the limitation of the variable load rate of the unit caused by inertia difference can be eliminated, and the peak shaving rate of the unit can be accelerated.

[0035] 2. The secondary reheat unit system provided by the present invention, the energy storage assembly includes a heat storage member and a cold storage member, and the heat storage member and the cold storage member are respectively connected to both ends of the second flow channel. During peak shaving of load reduction, the cold storage member releases a low-temperature medium to cool the reheated steam and reduce the amount of reheated steam; during peak shaving of load increase, the heat storage member releases a high-temperature medium to heat the condensate and increase the amount of reheated steam, which can accelerate the peak shaving rate of the unit.

[0036] 3. The operation method of the secondary reheat unit provided by the present invention, when the unit performs peak shaving operation of load reduction, the opening degree of the reheated steam regulating valve is accurately controlled according to the difference between the hot steam pressure and the pressure at the heat exchanger, which can ensure that during peak shaving of load reduction, the peak shaving rate of the unit can always be maintained at the highest point allowed by the system, ensuring that the unit operates at the maximum peak shaving rate. Description of the Drawings

[0037] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a schematic structural diagram of the secondary reheat unit system provided in the embodiments of the present invention.

[0039] Figure 2 It is a schematic operation diagram of the secondary reheat unit system provided in the embodiments of the present invention during load reduction for peak shaving.

[0040] Figure 3 It is a schematic operation diagram of the secondary reheat unit system provided in the embodiments of the present invention during load increase for peak shaving.

[0041] Explanation of reference numerals: 1. Heat storage element; 2. High-temperature medium regulating valve; 3. High-temperature medium pump; 4. Heat exchanger; 5. Low-temperature medium pump; 6. Low-temperature medium regulating valve; 7. Cold storage element; 8. Steam generator; 9. Ultra-high pressure cylinder; 10. General high-pressure cylinder; 11. Intermediate pressure cylinder; 12. Low-pressure cylinder; 13. Condenser; 14. Regenerative heater; 15. Reheat steam regulating valve; 16. Condensate regulating valve; 17. Condensate pump; 18. Generator. Specific Embodiments

[0042] The following will clearly and completely describe the technical solutions of the present invention with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" 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 or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] Embodiment 1

[0047] As Figure 1 shown, a secondary reheat unit system provided in this embodiment includes a steam turbine unit, a heat exchanger 4, and an energy storage assembly. Figure 1 The arrow direction in [the figure] is the flow direction of steam and condensate.

[0048] The steam inlet end of the steam turbine unit is connected to a steam generator 8, the steam outlet end of the steam turbine unit is connected to a regenerative heater 14, and a condenser 13 is connected between the steam outlet end of the steam turbine unit and the regenerative heater 14. The steam generator 8 in this embodiment is a coal-fired boiler, and in other embodiments, the steam generator 8 can also be a heater using other fuels.

[0049] One end of the first flow channel of the heat exchanger 4 is connected between the steam turbine unit and the steam generator 8, and the other end is connected to the condenser 13; a condensate regulating valve 16 is installed at the end of the first flow channel connected to the condenser 13, and a reheated steam regulating valve 15 is installed at the other end. A condensate pump 17 is installed between the condensate regulating valve 16 and the heat exchanger 4 for extracting part of the condensate from the condenser 13 during load increase and peak shaving. The energy storage assembly is connected to the second flow channel of the heat exchanger 4. The energy storage assembly includes a heat storage tank as the heat storage member 1 and a cold storage tank as the cold storage member 7. The heat storage member 1 and the cold storage member 7 are respectively connected to both ends of the second flow channel. A high-temperature medium regulating valve 2 is installed between the heat storage member 1 and the second flow channel. A low-temperature medium regulating valve 6 is installed between the cold storage member 7 and the second flow channel. The heat storage media in the cold storage member 7 and the heat storage member 1 are media with single-phase flow of molten salt. In order to facilitate the precise control of the flow rate and flow of the low-temperature medium and the high-temperature medium, a low-temperature medium pump 5 is installed between the low-temperature medium regulating valve 6 and the heat exchanger 4 for driving the high-temperature medium in the heat storage member 1 to move towards the heat exchanger 4 and finally stored in the cold storage member 7; a high-temperature medium pump 3 is installed between the high-temperature medium regulating valve 2 and the heat exchanger 4 for driving the low-temperature medium in the cold storage member 7 to move towards the heat exchanger 4 and finally stored in the heat storage member 1.

[0050] The steam turbine unit includes an ultra-high pressure cylinder 9, a high pressure cylinder 10, an intermediate pressure cylinder 11, and a low pressure cylinder 12. The ultra-high pressure cylinder 9, the high pressure cylinder 10, the intermediate pressure cylinder 11, and the low pressure cylinder 12 are respectively connected to the regenerative heater 14. The condenser 13 is installed between the low pressure cylinder 12 and the regenerative heater 14. The high pressure cylinder, the high pressure cylinder 10, the intermediate pressure cylinder 11, and the low pressure cylinder 12 are coaxially arranged, and a generator 18 is coaxially installed on the output shaft of the low pressure cylinder 12.

[0051] The steam generator 8 includes three-stage heating flow channels. Among them, the inlet end of the first-stage heating flow channel is connected to the regenerative heater 14, and the outlet end is connected to the ultra-high pressure cylinder 9; the inlet end of the second-stage heating flow channel is connected to the ultra-high pressure cylinder 9, and the outlet end is connected to the high pressure cylinder 10; the inlet of the third-stage heating flow channel is connected to the high pressure cylinder 10, and the outlet end is connected to the intermediate pressure cylinder 11. The outlet end of the intermediate pressure cylinder 11 is connected to the low pressure cylinder 12; the first flow channel is connected between the ultra-high pressure cylinder 9 and the second-stage heating flow channel.

[0052] When the secondary reheat unit system is peak-shaving during variable load operation, during the load reduction process, under the existing control strategy, the reheated steam is prone to under-temperature. When the secondary reheat unit system provided by the present invention is operating at a reduced load, the reheated steam regulating valve 15 is opened to extract part of the reheated steam, which enters the heat exchanger 4 for heat exchange, and its heat is stored in the energy storage component; during the load increase process, under the existing control strategy, the reheated steam is prone to over-temperature. When the secondary reheat unit system provided by the present invention is operating at an increased load, the condensate regulating valve 16 is opened to extract part of the condensate, which enters the heat exchanger 4 for heat exchange, is heated to the temperature of the primary cold reheated steam and then sent to the steam generator 8 for heat exchange. During the load reduction operation, the flow rate of the reheated steam is reduced, which can alleviate the under-temperature phenomenon of the reheated steam, and then reduce the amount of steam entering the steam turbine unit for work and the work done, and accelerate the load reduction rate of the unit. During the load increase operation, the flow rate of the reheated steam is increased, which can alleviate the over-temperature phenomenon of the reheated steam, improve the safety during the operation process, and increase the amount of steam entering the steam turbine for work and the work done, and accelerate the load increase rate of the unit. By setting the heat exchanger 4 and the energy storage component, and cooperating with the condensate regulating valve 16 and the reheated steam regulating valve 15 to perform peak-shaving for the secondary reheat unit system during variable load operation, it is possible to eliminate the limitation of the unit's variable load rate caused by inertia differences and accelerate the peak-shaving rate of the unit.

[0053] Embodiment 2

[0054] This embodiment provides a method for operating a secondary reheat unit, which is applied to the secondary reheat unit system described in Embodiment 1 and includes the following steps:

[0055] As Figure 2As shown in the figure, when the secondary reheat unit system operates at reduced load, the reheater steam regulating valve 15 is adjusted to extract the reheater steam from the regenerative heater 14 and release heat in the first flow channel of the heat exchanger 4. After releasing heat, the reheater steam flows into the condenser 13; the energy storage component controls the low-temperature medium to enter the second flow channel of the heat exchanger 4 to absorb heat. The high-temperature medium regulating valve 2 and the condensate regulating valve 16 are in the fully open state. Figure 2 The arrow direction on the pipeline between the cold energy storage component and the heat energy storage component is the flow direction of the low-temperature medium, and the rest of the arrows are the flow directions of steam and condensate in the power generation system.

[0056] The opening of the reheater steam regulating valve 15 is adjusted according to the following formula:

[0057]

[0058] In the above formula: ΔG 15 is the extraction steam flow rate of the primary cold reheater steam set according to the load change rate and load change range, with the unit of kg / s; Δp 15 is the pressure difference between the reheater steam pressure and the pressure at the heat exchanger, with the unit of MPa; ρ 15 is the reheater steam density, with the unit of kg / m 3 ; K v,15 is the resistance gain coefficient of the reheater steam regulating valve.

[0059] When the secondary reheat unit system operates at increased load, the opening of the low-temperature medium regulating valve 6 is adjusted according to the following formula:

[0060]

[0061] In the above formula: h rh is the enthalpy value of the reheater steam, with the unit of kJ / kg; h c is the enthalpy value of the condensate, with the unit of kJ / kg; h cr is the enthalpy value of the high-temperature heat storage medium, with the unit of kJ / kg; h cc is the enthalpy value of the low-temperature heat storage medium, with the unit of kJ / kg; ΔP6 is the pressure difference between the cold energy storage component and the heat exchanger, with the unit of MPa; ρ6 is the low-temperature medium density, with the unit of kg / m 3 ; K v,6 is the resistance gain coefficient of the low-temperature medium regulating valve.

[0062] As Figure 3 shown, when the secondary reheat unit system operates at increased load, the energy storage component works to control the high-temperature medium to enter the second flow channel of the heat exchanger 4 to release heat; the condensate regulating valve 16 is adjusted to extract the condensate to the first flow channel of the heat exchanger 4 to absorb heat, and the condensate after absorbing heat enters the steam generator 8. The low-temperature medium regulating valve 6 and the reheater steam regulating valve 15 are in the fully open state. Figure 2The arrow direction on the pipeline between the heat storage component and the cold storage component is the flow direction of the high-temperature medium, and the remaining arrows are the flow directions of steam and condensate in the power generation system.

[0063] The opening of the condensate regulating valve 16 is adjusted according to the following formula:

[0064]

[0065] In the above formula, Δg 16 is the condensate extraction flow rate set according to the load change rate and the load change range, with the unit of kg / s; Δp 16 is the pressure difference between the condenser and the heat exchanger, with the unit of MPa; ρ 16 is the condensate density, with the unit of kg / m 3 ; K v,16 is the resistance gain coefficient of the condensate regulating valve.

[0066] During the load increase operation of the secondary reheat unit system, the opening of the high-temperature medium regulating valve 2 is adjusted according to the following formula:

[0067]

[0068] In the above formula: h rh is the enthalpy value of the reheated steam, with the unit of kJ / kg; h c is the enthalpy value of the condensate, with the unit of kJ / kg; h cr is the enthalpy value of the high-temperature heat storage medium, with the unit of kJ / kg; h cc is the enthalpy value of the low-temperature heat storage medium, with the unit of kJ / kg; Δp2 is the pressure difference between the heat storage component and the heat exchanger, with the unit of MPa; ρ2 is the density of the low-temperature medium, with the unit of kg / m 3 ; K v,2 is the resistance gain coefficient of the high-temperature medium regulating valve.

[0069] During the load reduction process, under the existing control strategy, the reheated steam is prone to under-temperature. For the operation method during the load reduction process proposed in this embodiment, part of the cold reheated steam is extracted, exchanged heat with the low-temperature molten salt medium, and its heat is stored in the heat storage tank; the above method not only reduces the reheated steam flow rate, alleviates the under-temperature phenomenon of the reheated steam, but also reduces the steam volume entering the steam turbine for work, reduces the work done, and accelerates the load reduction rate of the unit. During the load increase process, under the existing control strategy, the reheated steam is prone to over-temperature. For the operation method during the load increase process proposed in this patent, part of the condensate is extracted, exchanged heat with the high-temperature molten salt medium, heated to the temperature of the primary cold reheated steam and sent to the boiler system for heat exchange; the above method not only increases the reheated steam flow rate, can alleviate the over-temperature phenomenon of the reheated steam, improves the safety during the operation process, but also increases the steam volume entering the steam turbine for work, increases the work done, and accelerates the load increase rate of the unit.

[0070] Aiming at the problem of large parameter fluctuations caused by the large inertia difference between the boiler side and the steam turbine side of the double reheat unit, it is proposed to realize the transfer of energy in time and space through the coupling of the heat storage tank. By means of the heat storage and heat release process of the heat storage tank, the problem of large parameter fluctuations during the load change process of the double reheat unit is alleviated, the load change rate of the double reheat unit is increased, and the flexible peak shaving ability of the double reheat unit is enhanced, providing conditions for the large-scale grid connection of renewable energy.

[0071] Obviously, the above embodiments are merely examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A secondary reheat unit system, characterized in that, Comprising: A steam turbine unit, the steam inlet end of which is connected to a steam generator (8), and the steam outlet end of which is connected to a regenerative heater (14). A condenser (13) is connected between the steam outlet end of the steam turbine unit and the regenerative heater (14); A heat exchanger (4), one end of the first flow channel of which is connected between the steam turbine unit and the steam generator (8), and the other end of which is connected to the condenser (13); A condensate regulating valve (16) is installed at the end of the first flow channel connected to the condenser (13), and a reheated steam regulating valve (15) is installed at the other end; An energy storage assembly, which is connected to the second flow channel of the heat exchanger (4). The energy storage assembly includes a heat storage member (1) and a cold storage member (7), and the heat storage member (1) and the cold storage member (7) are respectively connected to both ends of the second flow channel.

2. The secondary reheat unit system according to claim 1, wherein A high-temperature medium regulating valve (2) is installed between the heat storage member (1) and the second flow channel; A low-temperature medium regulating valve (6) is installed between the cold storage member (7) and the second flow channel.

3. The secondary reheat unit system according to claim 1 or 2, characterized in that, The steam turbine unit includes an ultra-high pressure cylinder (9), a general high pressure cylinder (10), an intermediate pressure cylinder (11) and a low pressure cylinder (12). The ultra-high pressure cylinder (9), the general high pressure cylinder (10), the intermediate pressure cylinder (11) and the low pressure cylinder (12) are all respectively connected to the regenerative heater (14), and the condenser (13) is installed between the low pressure cylinder (12) and the regenerative heater (14).

4. The secondary reheat unit system according to claim 3, characterized in that, The steam generator (8) includes three-stage heating flow channels. Among them, the inlet end of the first-stage heating flow channel is connected to the regenerative heater (14), and the outlet end is connected to the ultra-high pressure cylinder (9); The inlet end of the second-stage heating flow channel is connected to the ultra-high pressure cylinder (9), and the outlet end is connected to the general high pressure cylinder (10); The inlet of the third-stage heating flow channel is connected to the general high pressure cylinder (10), and the outlet end is connected to the intermediate pressure cylinder (11). The outlet end of the intermediate pressure cylinder (11) is connected to the low pressure cylinder (12); The first flow channel is connected between the ultra-high pressure cylinder (9) and the second-stage heating flow channel.

5. The secondary reheat unit system according to claim 1 or 2, characterized in that, A generator (18) is installed on the output shaft of the steam turbine unit.

6. A method for operating a secondary reheat unit, characterized in that, Applied to the secondary reheating unit system according to any one of claims 1 to 5, including the following steps: When the secondary reheating unit system operates at reduced load, the reheated steam regulating valve (15) is adjusted to extract the reheated steam in the regenerative heater (14) to release heat in the first flow channel of the heat exchanger (4), and the reheated steam after heat release flows into the condenser (13); The energy storage assembly controls the low-temperature medium to enter the second flow channel of the heat exchanger (4) to absorb heat; The opening degree of the reheated steam regulating valve (15) is adjusted according to the following formula: In the above formula: ΔG 15 is the extraction steam flow rate of the primary cold reheat steam set according to the variable load rate and variable load range, with the unit of kg / s; Δp 15 is the difference between the reheat steam pressure and the pressure at the heat exchanger, with the unit of MPa; ρ 15 is the reheat steam density, with the unit of kg / m 3 ; K v,15 is the resistance gain coefficient of the reheat steam regulating valve.

7. The operating method of the secondary reheat unit according to claim 6, characterized in that, Also included: When the secondary reheating unit system operates at increased load, the energy storage assembly works to control the high-temperature medium to enter the second flow channel of the heat exchanger (4) to release heat; The condensate regulating valve (16) is adjusted to extract condensate to the first flow channel of the heat exchanger (4) to absorb heat, and the condensate after heat absorption enters the steam generator (8); The opening degree of the condensate regulating valve (16) is adjusted according to the following formula: In the above formula, ΔG 16 is the condensate extraction flow rate set according to the variable load rate and variable load range, with the unit of kg / s; Δp 16 is the pressure difference between the condenser and the heat exchanger, with the unit of MPa; ρ 16 is the condensate density, with the unit of kg / m 3 ; K v,16 is the resistance gain coefficient of the condensate regulating valve.

8. The operation method of the secondary reheat unit according to claim 6 or 7, characterized in that, Also included: When the secondary reheat unit system operates at reduced load, the opening degree of the low-temperature medium regulating valve (6) is adjusted according to the following formula: In the above formula: h rh is the enthalpy value of the reheated steam, with the unit of kJ / kg; h c is the enthalpy value of the condensate, with the unit of kJ / kg; h cr is the enthalpy value of the high-temperature heat storage medium, with the unit of kJ / kg; h cc is the enthalpy value of the low-temperature heat storage medium, with the unit of kJ / kg; Δp6 is the pressure difference between the cold storage part and the heat exchanger, with the unit of MPa; ρ6 is the density of the low-temperature medium, with the unit of kg / m 3 ; K v,6 is the resistance gain coefficient of the regulating valve for the low-temperature medium.

9. The operating method of the secondary reheat unit according to claim 6 or 7, characterized in that, It also includes: When the secondary reheat unit system operates at increased load, the opening degree of the high-temperature medium regulating valve (2) is adjusted according to the following formula: In the above formula: h rh is the enthalpy value of the reheated steam, with the unit of kJ / kg; h c is the enthalpy value of the condensate, with the unit of kJ / kg; h cr is the enthalpy value of the high-temperature heat storage medium, with the unit of kJ / kg; h cc is the enthalpy value of the low-temperature heat storage medium, with the unit of kJ / kg; Δp2 is the pressure difference between the heat storage component and the heat exchanger, with the unit of MPa; ρ2 is the density of the low-temperature medium, with the unit of kg / m 3 ; K v,2 is the resistance gain coefficient of the high-temperature medium regulating valve.

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