Steam storage-based thermal power unit peak shaving system and peak shaving method

Abstract

The present application relates to a kind of steam energy storage-based thermal power unit peak shaving system and peak shaving method, including steam turbine, boiler and feedwater component, the boiler includes main steam pipe and reheat steam pipe;The feedwater component includes water supply component and heating component;The thermal power unit peak shaving system further includes steam heat storage system, and the steam heat storage system includes steam input component, high-pressure steam accumulator and low-pressure steam accumulator;The input end of the steam input component is at least connected with the output end of the main steam pipe, one of the output end of the steam input component is connected with the input end of the high-pressure steam accumulator, and the other output end is connected with the output end of the low-pressure steam accumulator;The output end of the high-pressure steam accumulator is connected with the heating component, and the output end of the low-pressure steam accumulator is at least connected with the steam input end of the low-pressure cylinder, with the advantages of low modification cost, quick peak shaving response and wide peak shaving range.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system peak shaving, in particular to a steam energy storage based thermal power unit peak shaving system and peak shaving method. BACKGROUND

[0002] The existing new energy power system has a series of problems in supply and demand balance, system regulation and stability characteristics due to the randomness and volatility of new energy (wind energy, light energy, etc.), which further leads to a low proportion of flexible regulation power sources in the power grid.

[0003] In order to realize the load balance of the new energy power system, the existing power system usually needs to be modified on the basis of the original system, for example, a molten salt energy storage system, an electrochemical energy storage system, a steam energy storage system, etc. are added to the original power system, and the molten salt energy storage system, the electrochemical energy storage system and the steam energy storage system are used to store and release energy to realize the peak shaving of the entire power system.

[0004] However, in the existing modification scheme, it is usually difficult to meet the demand for rapid peak shaving and wide load peak shaving of the power system, and the modification cost of the modification scheme represented by molten salt heat storage and electrochemical energy storage is large. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects in the prior art, thereby providing a steam energy storage based thermal power unit peak shaving system and peak shaving method.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] A steam energy storage based thermal power unit peak shaving system, comprising a steam turbine, a boiler for supplying steam to the steam turbine, and a feedwater assembly for supplying water to the boiler, wherein the steam turbine comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder; the boiler comprises a main steam pipe and a reheated steam pipe; the feedwater assembly comprises a water supply assembly and a heating assembly, wherein the heating assembly is used to heat the water supplied in the water supply assembly by using the steam extracted from the steam turbine; the thermal power unit peak shaving system further comprises a steam heat storage system, wherein the steam heat storage system comprises a steam input assembly, a high-pressure steam heat accumulator and a low-pressure steam heat accumulator; the input end of the steam input assembly is connected to the output end of the main steam pipe, one of the output ends of the steam input assembly is connected to the input end of the high-pressure steam heat accumulator, and the other output end is connected to the input end of the low-pressure steam heat accumulator; the output end of the high-pressure steam heat accumulator is connected to the heating assembly, and the output end of the low-pressure steam heat accumulator is connected to at least the steam input end of the low-pressure cylinder.

[0008] Preferably, the steam input assembly comprises a first check valve, a first regulating valve, a first desuperheater and a second desuperheater; the output end of the main steam pipe, the first check valve, the first regulating valve, one of the output ends of the first desuperheater, the input end of the high-pressure steam accumulator are connected in sequence; the output end of the main steam pipe, the first check valve, the first regulating valve, the other output end of the first desuperheater, the output end of the second desuperheater, the input end of the low-pressure steam accumulator are connected in sequence.

[0009] Preferably, the steam input assembly comprises a first check valve, a first regulating valve, a first desuperheater and a pressure matcher; the output end of the main steam pipe, the first check valve, the first regulating valve, the first desuperheater, the input end of the high-pressure steam accumulator are connected in sequence; the output end of the main steam pipe, the first check valve, the first regulating valve, the pressure matcher, the input end of the low-pressure steam accumulator are connected in sequence; the steam input assembly further comprises a second check valve and a second regulating valve; the exhaust end of the high-pressure cylinder, the second check valve, the second regulating valve, the pressure matcher, the input end of the low-pressure steam accumulator are connected in sequence.

[0010] Preferably, the steam accumulator system further comprises a first pipe assembly; the output end of the high-pressure steam accumulator and the heating assembly are connected through the first pipe assembly; the first pipe assembly comprises a third check valve and a third regulating valve; the high-pressure steam accumulator, the third check valve, the third regulating valve and the heating assembly are connected in sequence; the heating assembly comprises a plurality of high-pressure heaters; the third regulating valve is arranged in one-to-one correspondence with the high-pressure heaters.

[0011] Preferably, the steam accumulator system further comprises a second pipe assembly; the output end of the low-pressure steam accumulator and the steam input end of the low-pressure cylinder are connected through the second pipe assembly; the second pipe assembly comprises a fourth check valve, a fourth regulating valve and a pressure reducing valve; the output end of the low-pressure steam accumulator, the fourth check valve, the fourth regulating valve, the pressure reducing valve and the steam input end of the low-pressure cylinder are connected in sequence.

[0012] Preferably, the heating assembly comprises a low-pressure heater; the steam accumulator system further comprises a third pipe assembly; the third pipe assembly comprises a fifth check valve and a fifth regulating valve; the output end of the low-pressure steam accumulator, the fifth check valve, the fifth regulating valve, the steam input end of the low-pressure heater are connected in sequence.

[0013] A peak shaving method based on the above-mentioned steam storage-based thermal power unit peak shaving system, comprising the following steps: when the unit is load-reduced, the main steam of the unit is transported to the steam input assembly for treatment and stored in the high-pressure steam accumulator and the low-pressure steam accumulator; when the unit is load-increased, the steam generated by the high-pressure steam accumulator is supplied to the heating assembly of the feedwater assembly to replace at least part of the extraction steam of the heating assembly from the high-pressure cylinder and the intermediate-pressure cylinder of the steam turbine; when the unit is load-increased, the steam generated by the low-pressure steam accumulator and the exhaust steam of the intermediate-pressure cylinder are supplied to the low-pressure cylinder for work of the low-pressure cylinder.

[0014] Preferably, the method further comprises the following step: when the unit is load-increased, the steam generated by the low-pressure steam accumulator is supplied to the heating assembly of the feedwater assembly of the low-pressure cylinder to replace at least part of the extraction steam of the heating assembly from the low-pressure cylinder of the steam turbine.

[0015] Preferably, the step of supplying the steam generated by the high-pressure steam accumulator to the heating assembly of the feedwater assembly to replace at least part of the extraction steam of the heating assembly from the high-pressure cylinder and the intermediate-pressure cylinder of the steam turbine comprises the following steps: first, replacing the extraction steam of the heating assembly from the high-pressure cylinder with the steam generated by the high-pressure steam accumulator; and then, replacing the extraction steam of the heating assembly from the intermediate-pressure cylinder with the steam generated by the high-pressure steam accumulator.

[0016] Preferably, the method further comprises the following steps:

[0017] When the unit is load-reduced, adjusting the total flow of the main steam transported and stored in the high-pressure steam accumulator and / or the low-pressure steam accumulator to adjust the load-reduction rate of the unit;

[0018] When the unit is load-increased, adjusting the flow of the steam generated by the high-pressure steam accumulator and transported to the heating assembly, and / or adjusting the flow of the steam generated by the low-pressure steam accumulator and transported to the low-pressure cylinder and / or the heating assembly to adjust the load-increase rate of the unit.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] The aforementioned technical solution provides a peak-shaving system for thermal power units based on steam energy storage. This system connects the input end of a steam input component to the output end of the main steam pipe, connects one output end of the steam input component to the input end of a high-pressure steam accumulator, and the other output end to the output end of a low-pressure steam accumulator. Simultaneously, the output end of the high-pressure steam accumulator is connected to a heating component, and the output end of the low-pressure steam accumulator is connected to the steam input end of the low-pressure cylinder. When the unit requires rapid load reduction, the high-temperature, high-pressure steam output from the main steam pipe can be stored in multiple stages. Specifically, after processing by the steam input component, it is stored separately in the high-pressure and low-pressure steam accumulators. This not only rapidly reduces the amount of steam supplied to the high-pressure cylinder of the turbine, thereby quickly reducing the turbine's output power, but also stores the energy of the high-temperature, high-pressure steam output from the main steam pipe, preventing energy waste. When the unit has a rapid load increase requirement, the high-pressure water in the high-pressure steam accumulator is converted into steam to supply the heating components. This replaces at least part of the steam extracted from the turbine to preheat the water fed into the boiler, satisfying the water preheating requirement while reducing the turbine's steam extraction volume, thus rapidly increasing the turbine's output power. Furthermore, the high-pressure water stored in the low-pressure steam accumulator can be converted into steam to supply the low-pressure cylinder. Simultaneously, the exhaust steam from the intermediate-pressure cylinder is also supplied to the low-pressure cylinder, increasing the steam intake of the low-pressure cylinder and further coordinating with the high-pressure steam accumulator to rapidly increase the turbine's output power. Moreover, this scheme, through the coordinated operation of the turbine, feedwater components, main steam pipe, high-pressure steam accumulator, and low-pressure steam accumulator, effectively increases the peak-shaving range of the entire unit. Correspondingly, the peak-shaving method of the thermal power unit peak-shaving system based on the above steam energy storage has the advantages of low retrofit cost, rapid peak-shaving response, and wide peak-shaving range. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the first embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the second embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the third embodiment of the present invention.

[0025] Figure 4The output power of the steam storage system during the period of unit load increase is provided by the embodiment of the present application.

[0026] Figure 5 The schematic diagram of steam storage system steam generation and power generation distribution under different working conditions of the system is provided by the embodiment of the present application.

[0027] Explanation of reference signs:

[0028] 1, steam turbine; 11, high-pressure cylinder; 12, intermediate-pressure cylinder; 13, low-pressure cylinder; 2, boiler; 21, main steam pipe; 22, reheat steam pipe; 3, feedwater assembly; 31, water supply assembly; 311, delivery pipe; 312, condenser; 313, condensate pump; 314, deaerator; 315, feedwater pump; 32, heating assembly; 321, first high-pressure heater; 322, second high-pressure heater; 323, third high-pressure heater; 324, low-pressure heater; 4, steam storage system; 41, steam input assembly; 411, first check valve; 412, first regulating valve; 413, first temperature and pressure reducer; 414, second temperature and pressure reducer; 415, second check valve; 416, second regulating valve; 417, pressure matcher; 42, high-pressure steam accumulator; 43, low-pressure steam accumulator; 44, first pipe assembly; 441, third check valve; 442, third regulating valve; 45, second pipe assembly; 451, fourth check valve; 452, fourth regulating valve; 453, pressure reducing valve; 46, third pipe assembly; 461, fifth check valve; 462, fifth regulating valve; 5, pipe fitting; 51, sixth check valve; 6, first extraction valve; 7, second extraction valve. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0030] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] Embodiment one

[0033] Referring to Figure 1 The embodiment of the present application provides a steam storage-based peak regulation system of thermal power generating unit, which comprises a steam turbine 1, a boiler 2 and a feedwater assembly 3; wherein the boiler 2 is used for delivering steam to the steam turbine 1 to drive the steam turbine 1 to work and generate electricity, and the feedwater assembly 3 is used for delivering water to the boiler 2 to form steam.

[0034] Specifically, the steam turbine 1 comprises a high-pressure cylinder 11, a medium-pressure cylinder 12 and a low-pressure cylinder 13, and the boiler 2 comprises a main steam pipe 21 and a reheated steam pipe 22. The main steam pipe 21 provides high-temperature and high-pressure hot steam, which is mainly used for the high-pressure cylinder 11 of the steam turbine 1; the reheated steam pipe 22 provides high-temperature and high-pressure hot steam heated by secondary heating, which is mainly used for the medium-pressure cylinder 12, and the input end of the reheated steam pipe 22 is connected with the exhaust end of the high-pressure cylinder 11, so that the exhaust steam of the high-pressure cylinder 11 is heated by the reheated steam pipe 22 of the boiler 2 and then supplied to the medium-pressure cylinder 12. The feedwater assembly 3 comprises a water delivery assembly 31 and a heating assembly 32, and the heating assembly 32 is used for heating the water delivered in the water delivery assembly 31 by the extraction steam of the steam turbine 1, so that the peak regulation of the unit can be realized and the water entering the boiler 2 can be preheated.

[0035] In order to meet the requirement of rapid peak regulation, in the embodiment, the peak regulation system of thermal power generating unit further comprises a steam storage system 4.

[0036] Specifically, the steam storage system 4 comprises a steam input assembly 41, a high-pressure steam accumulator 42 and a low-pressure steam accumulator 43; the input end of the steam input assembly 41 is connected with at least the output end of the main steam pipe 21, one of the output ends of the steam input assembly 41 is connected with the input end of the high-pressure steam accumulator 42, and the other output end is connected with the output end of the low-pressure steam accumulator 43; the output end of the high-pressure steam accumulator 42 is connected with the heating assembly 32, and the output end of the low-pressure steam accumulator 43 is connected with at least the steam input end of the low-pressure cylinder 13.

[0037] By connecting the input end of the steam input assembly 41 with the output end of the main steam pipe 21, connecting one of the output ends of the steam input assembly 41 with the input end of the high-pressure steam accumulator 42 and the other output end with the output end of the low-pressure steam accumulator 43, and simultaneously connecting the output end of the high-pressure steam accumulator 42 with the heating assembly 32 and the output end of the low-pressure steam accumulator 43 with the steam input end of the low-pressure cylinder 13, when the unit has a rapid load reduction demand, the high-temperature and high-pressure steam output by the main steam pipe 21 can be stored in multiple stages, that is, after being processed by the steam input assembly 41, the high-temperature and high-pressure steam is stored in the high-pressure steam accumulator 42 and the low-pressure steam accumulator 43, which can not only quickly reduce the amount of steam supplied to the high-pressure cylinder 11 of the steam turbine 1, thereby quickly reducing the output power of the steam turbine 1, but also can store the energy of the high-temperature and high-pressure steam output by the main steam pipe 21, thereby avoiding energy waste. When the unit has a rapid load increase demand, the high-pressure water in the high-pressure steam accumulator 42 is converted into steam to supply the heating assembly 32 to replace at least part of the steam extraction of the steam turbine 1 to preheat the water fed into the boiler 2, which can not only meet the demand of preheating the water fed into the boiler 2, but also can reduce the amount of steam extraction of the steam turbine 1, thereby quickly increasing the output power of the steam turbine 1. In addition, the high-pressure water stored in the low-pressure steam accumulator 43 can also be converted into steam to supply the low-pressure cylinder 13, and the exhaust steam of the medium-pressure cylinder 12 is also supplied to the low-pressure cylinder 13, thereby increasing the amount of steam into the low-pressure cylinder 13, which further cooperates with the high-pressure steam accumulator 42 to quickly increase the output power of the steam turbine 1.

[0038] As can be seen from the above, through the cooperation of the steam turbine 1, the feedwater assembly 3, the main steam pipe 21, the high-pressure steam accumulator 42 and the low-pressure steam accumulator 43, the peak regulation range of the entire unit can be effectively increased. The entire steam accumulation system 4 has a simple structure, and when the original power system is modified, the modification cost is lower.

[0039] Referring to Figure 1 In this embodiment, the steam input assembly 41 includes a first check valve 411, a first regulating valve 412, a first desuperheater 413 and a second desuperheater 414.

[0040] Specifically, the output end of the main steam pipe 21, the first check valve 411, the first regulating valve 412, one of the output ends of the first desuperheater 413, and the input end of the high-pressure steam accumulator 42 are sequentially connected. The output end of the main steam pipe 21, the first check valve 411, the first regulating valve 412, the other output end of the first desuperheater 413, the second desuperheater 414, and the low-pressure steam accumulator 43 are sequentially connected. It can be known that when the unit load is reduced, the first check valve 411 and the first regulating valve 412 are opened, and the high-parameter (such as high-temperature and high-pressure) steam output from the output end of the main steam pipe 21 sequentially passes through the first check valve 411, the first regulating valve 412, and the first desuperheater 413. After the temperature and pressure are reduced by the first desuperheater 413, the steam is divided into two paths, one of which is input into the high-pressure steam accumulator 42 through one of the output ends for storage, and the other of which is input into the second desuperheater 414 through the other output end, and after the temperature and pressure are reduced by the second desuperheater 414, the steam is stored in the low-pressure steam accumulator 43.

[0041] Referring to Figure 1 The connection mode between the output end of the high-pressure steam accumulator 42 and the heating assembly 32 is various, and in the embodiment, the steam accumulator system 4 further includes a first pipe assembly 44. The output end of the high-pressure steam accumulator 42 and the heating assembly 32 are connected through the first pipe assembly 44.

[0042] Specifically, the first pipe assembly 44 includes a third check valve 441 and a third regulating valve 442, and the high-pressure steam accumulator 42, the third check valve 441, the third regulating valve 442, and the heating assembly 32 are sequentially connected. The heating assembly 32 includes a plurality of high-pressure heaters, and the third regulating valve 442 is arranged in one-to-one correspondence with the high-pressure heaters.

[0043] Further, in the embodiment, the high-pressure heater includes the first high-pressure heater 321, the second high-pressure heater 322 and the third high-pressure heater 323 connected in sequence along the water delivery direction of the water delivery assembly 31, and the third regulating valve 442 corresponding to the first high-pressure heater 321, the second high-pressure heater 322 and the third high-pressure heater 323 is also provided with three, respectively. When the unit is loaded, first, the third check valve 441 and the third regulating valve 442 corresponding to the third high-pressure heater 323 are opened, and the steam generated by the high-pressure steam accumulator 42 is sequentially delivered to the third high-pressure heater 323 through the third check valve 441 and the third regulating valve 442 corresponding to the third high-pressure heater 323. Then, when the steam generated by the high-pressure steam accumulator 42 is still surplus (for example, the steam generated by the high-pressure steam accumulator 42 completely replaces the extraction of the third high-pressure heater 323 from the high-pressure cylinder 11), the third regulating valve 442 corresponding to the second high-pressure heater 322 is opened. Finally, similarly, if the steam generated by the high-pressure steam accumulator 42 is still surplus, the third regulating valve 442 corresponding to the first high-pressure heater 321 is opened.

[0044] It is worth noting that three high-pressure heaters are taken as an example in the embodiment, and a plurality of high-pressure heaters can also be provided in other embodiments, and the steam generated by the high-pressure steam accumulator 42 is preferentially supplied to the downstream high-pressure heater (i.e. the downstream of the water delivery direction of the water delivery assembly 31). Correspondingly, it can be known that in order to meet the extraction control, the first extraction valve 6 is also provided between the extraction end of the steam turbine 1 and the heating assembly 32, and when the extraction of the heating assembly 32 from the steam turbine 1 can be completely replaced by the steam generated by the high-pressure steam accumulator 42, the first extraction valve 6 can be kept closed to improve the output efficiency of the steam turbine 1.

[0045] Referring to Figure 1 , the connection mode between the output end of the low-pressure steam accumulator 43 and the steam input end of the low-pressure cylinder 13 has many kinds, and in the embodiment, the steam accumulator system 4 further includes a second pipe assembly 45, and the output end of the low-pressure steam accumulator 43 and the steam input end of the low-pressure cylinder 13 are connected through the second pipe assembly 45.

[0046] Specifically, the second pipe assembly 45 includes a fourth check valve 451, a fourth regulating valve 452 and a pressure reducing valve 453, and the output end of the low-pressure steam accumulator 43, the fourth check valve 451, the fourth regulating valve 452, the pressure reducing valve 453 and the steam input end of the medium-pressure cylinder 12 are connected in sequence.

[0047] Further, the medium-pressure cylinder 12 and the low-pressure cylinder 13 are connected through the pipe 5, and the sixth check valve 51 is provided on the pipe 5, and the downstream of the sixth check valve 51 is connected with the second pipe assembly 45.

[0048] When the unit is ascending load, the fourth check valve 451, the fourth regulating valve 452, the pressure reducing valve 453 and the sixth check valve 51 are all opened, at this time, the steam outputted from the output end of the low-pressure steam accumulator 43 is delivered to the low-pressure cylinder 13 through the fourth check valve 451, the fourth regulating valve 452 and the pressure reducing valve 453, the fourth check valve 451 can prevent the steam from flowing back, and the sixth check valve 51 can prevent the steam from flowing back to the intermediate-pressure cylinder 12.

[0049] The feedwater assembly 3 can be provided in various structures, and can feed water to the boiler 2 and preheat the water during the feeding.

[0050] Referring to Figure 1 In the embodiment, the heating assembly 32 comprises a first high-pressure heater 321, a second high-pressure heater 322 and a third high-pressure heater 323 connected in sequence along the feeding direction; the steam input end of the first high-pressure heater 321 is connected with the steam extraction end of the intermediate-pressure cylinder 12, so as to heat the water delivered in the feedwater assembly 31 by using the steam extracted from the intermediate-pressure cylinder 12; the second high-pressure heater 322 is connected with the first steam extraction end of the high-pressure cylinder 11, and the third high-pressure heater 323 is connected with the second steam extraction end of the high-pressure cylinder 11, and the steam temperature of the first steam extraction end of the high-pressure cylinder 11 is lower than that of the second steam extraction end of the high-pressure cylinder 11, so as to heat the water delivered in the feedwater assembly 31 by using the steam extracted from the high-pressure cylinder 11. It can be known that, in the above embodiment, the steam temperature inputted into the first high-pressure heater 321, the second high-pressure heater 322 and the third high-pressure heater 323 increases in sequence, so as to realize the step-by-step heating of the water delivered in the feedwater assembly 31, thereby increasing the heat exchange efficiency.

[0051] Further, the heating assembly 32 further comprises a low-pressure heater 324 located upstream of the first high-pressure heater 321 (i.e. upstream along the feeding direction), and the steam input end of the low-pressure heater 324 is connected with the steam extraction end of the low-pressure cylinder 13, so as to heat the water delivered in the feedwater assembly 31 by using the steam in the low-pressure cylinder 13.

[0052] Still further, in order to realize the reuse of the steam in the low-pressure cylinder 13, in the embodiment, the feedwater assembly 31 comprises a plurality of delivery pipes 311, a condenser 312, a condensate pump 313, a deaerator 314 and a feedwater pump 315. It can be known that the delivery pipes 311 are provided in plurality, and are used for feeding water and various components.

[0053] Specifically, from the steam exhaust end of the low-pressure cylinder 13 to the boiler 2, the plurality of delivery pipes 311 are connected in sequence with the steam exhaust end of the low-pressure cylinder 13, the condenser 312, the condensate pump 313, the low-pressure heater 324, the deaerator 314, the feedwater pump 315, the first high-pressure heater 321, the second high-pressure heater 322, the third high-pressure heater 323 and the boiler 2, so as to form the water feeding path of the boiler 2.

[0054] Embodiment Two

[0055] Referring to Figure 2 , based on the above-mentioned Embodiment One, in this embodiment, the steam storage system 4 further comprises a third pipe assembly 46; the third pipe assembly 46 comprises a fifth non-return valve 461 and a fifth regulating valve 462; the output end of the low-pressure steam storage device 43, the fifth non-return valve 461, the fifth regulating valve 462, and the steam input end of the low-pressure heater 324 are sequentially connected.

[0056] When the unit is ascending load, the fifth non-return valve 461 and the fifth regulating valve 462 are opened, and the steam output by the low-pressure steam storage device 43 is delivered to the steam input end of the low-pressure heater 324 through the fifth non-return valve 461 and the fifth regulating valve 462, instead of the extraction steam from the low-pressure cylinder 13 to the low-pressure heater 324, to heat the condensate (water delivered in the delivery pipe 311 of the water delivery assembly 31), which can improve the output power of the low-pressure cylinder 13 to a certain extent.

[0057] It can be known that the second extraction valve 7 is arranged between the low-pressure heater 324 and the communication pipeline of the low-pressure cylinder 13, and when the steam output by the low-pressure steam storage device 43 can replace the extraction steam from the low-pressure cylinder 13 to the low-pressure heater 324, the second extraction valve 7 is closed.

[0058] Embodiment Three

[0059] Referring to Figure 3 , based on the above-mentioned Embodiment Two, the difference of this embodiment is that: the steam input assembly 41 comprises a first non-return valve 411, a first regulating valve 412, a first desuperheater 413, and a pressure matching device 417; the output end of the main steam pipe 21, the first non-return valve 411, the first regulating valve 412, the first desuperheater 413, and the input end of the high-pressure steam storage device 42 are sequentially connected; the output end of the main steam pipe 21, the first non-return valve 411, the first regulating valve 412, the pressure matching device 417, and the input end of the low-pressure steam storage device 43 are sequentially connected; the steam input assembly 41 further comprises a second non-return valve 415 and a second regulating valve 416, and the exhaust end of the high-pressure cylinder 11, the second non-return valve 415, the second regulating valve 416, the pressure matching device 417, and the input end of the low-pressure steam storage device 43 are sequentially connected.

[0060] It can be known that when the unit reduces load, the first check valve 411, the first regulating valve 412, the second check valve 415 and the second regulating valve 416 are all opened, and the high-parameter (such as high temperature and high pressure) steam output from the output end of the main steam pipe 21 can be divided into two routes after passing through the first check valve 411 and the first regulating valve 412, one of which is sent to the high-pressure steam accumulator 42 for storage after being reduced in temperature and pressure by the first temperature and pressure reducer 413, and the other is sent to the low-pressure steam accumulator 43 through the pressure matcher 417. At the same time, the exhaust steam of the high-pressure cylinder 11 is sent to the pressure matcher 417 through the second check valve 415 and the second regulating valve 416, and is sent to the low-pressure steam accumulator 43 through the pressure matcher 417. It can be known that the high-pressure steam sent from the first check valve 411 and the first regulating valve 412, and the relatively low-pressure steam sent from the second check valve 415 and the second regulating valve 416, are collectively input into the low-pressure steam accumulator 43 after being matched in pressure by the pressure matcher 417. This mode can not only reduce the amount of main steam supplied to the high-pressure cylinder 11, but also store the exhaust steam of the high-pressure cylinder 11, thereby reducing the amount of steam supplied to the medium-pressure cylinder 12 by the high-pressure cylinder 11 through the reheated steam pipe 22, and further rapidly reducing the output power of the steam turbine 1.

[0061] In addition, by controlling the opening degrees of the first regulating valve 412 and the second regulating valve 416, the steam supply amount of the high-pressure cylinder 11 and the steam supply amount of the medium-pressure cylinder 12 can be controlled, thereby meeting different load requirements of the unit and increasing the peak shaving range of the unit.

[0062] It is worth noting that the connection between the above-mentioned system structures is connected through pipelines, and the corresponding valve structures are arranged on the pipelines.

[0063] Embodiment Four

[0064] Based on the above-mentioned embodiments, the embodiment further provides a peak shaving method comprising the following steps:

[0065] When the unit reduces load, the main steam of the unit is sent to be treated by the steam input assembly 41 and is stored in the high-pressure steam accumulator 42 and the low-pressure steam accumulator 43;

[0066] When the unit increases load, the steam generated by the high-pressure steam accumulator 42 is supplied to the heating assembly 32 of the feedwater assembly 3 to replace at least part of the extraction steam of the heating assembly 32 from the high-pressure cylinder 11 and the medium-pressure cylinder 12 of the steam turbine 1;

[0067] When the unit increases load, the steam generated by the low-pressure steam accumulator 43 and the exhaust steam of the medium-pressure cylinder 12 are supplied to the low-pressure cylinder 13 for work of the low-pressure cylinder 13.

[0068] Further, the steam generated by the high-pressure steam accumulator 42 is supplied to the heating assembly 32 of the feedwater assembly 3 to replace at least part of the extraction steam of the heating assembly 32 from the high-pressure cylinder 11 and the intermediate-pressure cylinder 12 of the steam turbine 1; the method comprises the following steps:

[0069] First, the steam generated by the high-pressure steam accumulator 42 replaces the extraction steam of the heating assembly 32 from the high-pressure cylinder 11;

[0070] Then, the steam generated by the high-pressure steam accumulator 42 replaces the extraction steam of the heating assembly 32 from the intermediate-pressure cylinder 12.

[0071] The peak shaving method further comprises the following steps: when the unit is increasing load, the steam generated by the low-pressure steam accumulator 43 is supplied to the low-pressure cylinder 13 to supply the heating assembly 32 (specifically, the low-pressure heater 324) of the feedwater assembly 3 to replace at least part of the extraction steam of the heating assembly 32 from the low-pressure cylinder 13 of the steam turbine 1.

[0072] Further, in order to meet the adjustment requirements of the load increase and decrease rate and range of the unit, in the embodiment, the method further comprises the following steps:

[0073] When the unit is decreasing load, the total main steam flow delivered and stored to the high-pressure steam accumulator 42 and the low-pressure steam accumulator 43 is adjusted to adjust the load decrease rate of the unit. Specifically, when the unit is decreasing load, the total main steam flow delivered to the high-pressure steam accumulator 42 and the low-pressure steam accumulator 43 can be adjusted, when the total main steam flow is relatively large (the proportion of the total main steam flow to the main steam flow output by the boiler 2 is large), the amount of main steam corresponding to the main steam delivered to the intermediate-pressure cylinder 12 by the boiler 2 is rapidly reduced, and the reduced amount of steam is relatively large, thereby realizing rapid adjustment of the load decrease rate, and when the total main steam flow is relatively small (the proportion of the total main steam flow to the main steam flow output by the boiler 2 is small), the amount of main steam corresponding to the main steam delivered to the intermediate-pressure cylinder 12 by the boiler 2 is reduced relatively slowly, and the load decrease rate of the unit is relatively slow.

[0074] Further, in order to meet the adjustment requirements of the load increase and decrease rate and range of the unit, in the embodiment, the method further comprises the following steps:

[0075] When the unit is increasing load, the steam flow delivered to the heating assembly 32 by the high-pressure steam accumulator 42 is adjusted to adjust the load increase rate of the unit.

[0076] When the unit is increasing load, the steam flow delivered to the low-pressure cylinder 13 by the low-pressure steam accumulator 43 can also be adjusted, and the steam flow delivered to the heating assembly 32 by the low-pressure steam accumulator 43 can also be adjusted to adjust the load increase rate of the unit.

[0077] It can be known that the specific flow regulation mode can be adjusted according to the actual demand, that is, the corresponding valve opening degree. In addition, when the unit is loaded, the steam flow delivered by the high-pressure steam accumulator 42 to the heating assembly 32 can be adjusted to adjust the load rate of the unit, and the steam flow delivered by the low-pressure steam accumulator 43 to the low-pressure cylinder 13 and the heating assembly 32 can be adjusted to adjust the load rate of the unit, for example, when rapid adjustment is required. Of course, in other embodiments, only the steam flow delivered by the high-pressure steam accumulator 42 can be adjusted. The steam flow delivered by the high-pressure steam accumulator 42 can also be adjusted first, and then the steam flow delivered by the low-pressure steam accumulator 43 can be adjusted. The steam of the low-pressure steam accumulator 43 can also be supplied only to the low-pressure cylinder 13, and can also be supplied only to the heating assembly 32. The specific selection can be made according to the actual demand to adjust the peak regulation rate.

[0078] Based on the actual application of the above-mentioned embodiment one, when the existing thermal power unit is actually improved according to embodiment one, taking a typical 300 MW subcritical unit as an example, in order to achieve a variable load rate of more than 5% per minute, the boiler 2 side can reach a variable load rate of 2.5-3% per minute after optimization, and the steam accumulation comprehensive adjustment of the steam turbine 1 side can reach a variable load rate of 0-0.5% per minute. By adding the steam accumulation system 4, a variable load rate of 2.5-3% per minute can be achieved.

[0079] The overall design idea of the steam accumulation system 4 is to meet the main AGC instruction application scenarios and the variable load demand of the steam turbine 1 side, determine the continuous operation time of the rapid variable load of the thermal power unit, and then determine the steam amount required to be provided by the steam accumulation system 4 according to the work increment calculation of the steam turbine 1, and finally determine the basic design parameters of the steam accumulation system 4. Through AGC scene analysis on the AGC instruction data of a representative power plant, the design selection of 15% Pe corresponding steam capacity of the steam accumulator can meet most application scenarios.

[0080] Referring to Figure 4 , Figure 4 The steam accumulation system 4 of the 300 MW subcritical unit coupled system supplies steam during the process of increasing from 30% Pe to 45% Pe; the unit completes the load increase operation in 3 min, and the steam supply amount of the steam accumulation system 4 gradually increases in the first 3 min, and the steam production amount reaches a peak at the third minute, corresponding to an electric power of 27 MW; after that, the steam accumulation system 4 continues to supply steam, and the steam supply amount gradually decreases until the steam production amount of the boiler 2 reaches the stable load level.

[0081] As can be known from the above example, the steam produced by the steam accumulation system 4 can be used in the following ways:

[0082] The water is heated by the high-pressure heater of the heating assembly 32, and the extraction steam from the high-pressure cylinder 11 and the intermediate-pressure cylinder 12 of the steam turbine 1 is reduced or replaced.

[0083] The low-pressure cylinder 13 is directly supplied with the steam for work and power generation.

[0084] The water is heated by the low-pressure heater 324 of the heating assembly 32, and the extraction steam from the low-pressure cylinder 13 of the steam turbine 1 is reduced or replaced.

[0085] The steam storage system 4 can meet the difference adjustment of the steam distribution ratio under different operating loads of the unit through the cooperation of the above-mentioned modes and the adjustment of the steam amount. Figure 5 , Figure 5 The above-mentioned difference is quantitatively shown, and the instantaneous maximum steam production capacity of the steam storage system 4 can reach 27 MW corresponding to the steam flow. Under the low load of the unit, the extraction steam amount of the high-pressure heater is relatively small, and the power generation amount corresponding to the extraction steam cannot meet the demand of the unit load increase, so most of the steam production of the steam storage system 4 needs to be distributed to the low-pressure cylinder 13 for direct power generation. With the increase of the unit load, the demand of the high-pressure steam increases, and the steam production of the steam storage system 4 can be more distributed to the heating assembly 32 (preferably the high-pressure heater), and the steam amount distributed to the low-pressure cylinder 13 gradually decreases.

[0086] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application. Any non-essential changes and replacements made by the person skilled in the art on the basis of the present application all belong to the protection scope of the present application.

Claims

1. A steam storage based peak shaving system for thermal power unit, comprising a steam turbine (1), a boiler (2) for delivering steam to the steam turbine (1), and a feedwater assembly (3) for delivering water to the boiler (2), wherein the steam turbine (1) comprises a high pressure cylinder (11), a medium pressure cylinder (12) and a low pressure cylinder (13) ; characterized in that, the boiler (2) comprises a main steam pipe (21) and a reheat steam pipe (22) ; the feedwater assembly (3) comprises a water delivery assembly (31) and a heating assembly (32), wherein the heating assembly (32) is configured to heat water delivered in the water delivery assembly (31) by using extraction steam of the steam turbine (1) ; and the peak shaving system further comprises a steam storage system (4), wherein the steam storage system (4) comprises a steam input assembly (41), a high pressure steam accumulator (42) and a low pressure steam accumulator (43) ; an input end of the steam input assembly (41) is connected to an output end of the main steam pipe (21), one output end of the steam input assembly (41) is connected to an input end of the high pressure steam accumulator (42), and another output end of the steam input assembly (41) is connected to an input end of the low pressure steam accumulator (43) ; an output end of the high pressure steam accumulator (42) is connected to the heating assembly (32), and an output end of the low pressure steam accumulator (43) is connected to at least a steam input end of the low pressure cylinder (13). 2.The steam storage based peak shaving system for thermal power unit according to claim 1, characterized in that, the steam input assembly (41) comprises a first check valve (411), a first regulating valve (412), a first desuperheater (413) and a second desuperheater (414) ; the output end of the main steam pipe (21), the first check valve (411), the first regulating valve (412), one output end of the first desuperheater (413), and the input end of the high pressure steam accumulator (42) are sequentially connected; and the output end of the main steam pipe (21), the first check valve (411), the first regulating valve (412), another output end of the first desuperheater (413), an output end of the second desuperheater (414), and the input end of the low pressure steam accumulator (43) are sequentially connected. 3.The steam storage based peak shaving system for thermal power unit according to claim 1, characterized in that, the steam input assembly (41) comprises a first check valve (411), a first regulating valve (412), a first desuperheater (413) and a pressure matcher (417) ; the output end of the main steam pipe (21), the first check valve (411), the first regulating valve (412), the first desuperheater (413), and the input end of the high pressure steam accumulator (42) are sequentially connected; and the output end of the main steam pipe (21), the first check valve (411), the first regulating valve (412), the pressure matcher (417), and the input end of the low pressure steam accumulator (43) are sequentially connected. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The steam input assembly (41) further comprises a second check valve (415) and a second regulating valve (416), and the exhaust end of the high-pressure cylinder (11), the second check valve (415), the second regulating valve (416), the pressure matcher (417), and the input end of the low-pressure steam accumulator (43) are sequentially connected.

4. The system according to any one of claims 1 to 3, characterized in that, The steam accumulator system (4) further comprises a first pipe assembly (44); The output end of the high-pressure steam accumulator (42) and the heating assembly (32) are connected through the first pipe assembly (44); The first pipe assembly (44) comprises a third check valve (441) and a third regulating valve (442), and the high-pressure steam accumulator (42), the third check valve (441), the third regulating valve (442), and the heating assembly (32) are sequentially connected; The heating assembly (32) comprises a plurality of high-pressure heaters, and the third regulating valve (442) is arranged in one-to-one correspondence with the high-pressure heaters.

5. The system according to any one of claims 1-3, characterized in that, The steam accumulator system (4) further comprises a second pipe assembly (45); The output end of the low-pressure steam accumulator (43) and the steam input end of the low-pressure cylinder (13) are connected through the second pipe assembly (45); The second pipe assembly (45) comprises a fourth check valve (451), a fourth regulating valve (452), and a pressure reducing valve (453); The output end of the low-pressure steam accumulator (43), the fourth check valve (451), the fourth regulating valve (452), the pressure reducing valve (453), and the steam input end of the low-pressure cylinder (13) are sequentially connected.

6. The system according to any one of claims 1-3, wherein, The heating assembly (32) comprises a low-pressure heater (324); The steam accumulator system (4) further comprises a third pipe assembly (46); The third pipe assembly (46) comprises a fifth check valve (461) and a fifth regulating valve (462); The output end of the low-pressure steam accumulator (43), the fifth check valve (461), the fifth regulating valve (462), and the steam input end of the low-pressure heater (324) are sequentially connected.

7. A method for peak regulation of a steam accumulation based thermal power unit peak regulation system according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: When the unit load is reduced, the main steam of the unit is transported to the steam input assembly (41) for processing and stored in the high-pressure steam accumulator (42) and the low-pressure steam accumulator (43); When the unit load is increased, the steam generated by the high-pressure steam accumulator (42) is supplied to the heating assembly (32) of the feedwater assembly (3) to replace at least part of the extraction steam of the heating assembly (32) from the high-pressure cylinder (11) and the intermediate-pressure cylinder (12) of the steam turbine (1); When the unit load is increased, the steam generated by the low-pressure steam accumulator (43) and the exhaust steam of the intermediate-pressure cylinder (12) are supplied to the low-pressure cylinder (13) for work of the low-pressure cylinder (13).

8. The peak shaving method of claim 7, wherein, The method further comprises the following steps: When the unit load is increased, the steam generated by the low-pressure steam accumulator (43) is supplied to the heating assembly (32) of the feedwater assembly (3) to replace at least part of the extraction steam of the heating assembly (32) from the low-pressure cylinder (13) of the steam turbine (1).

9. The peak shaving method of claim 7, wherein, The steam generated by the high-pressure steam accumulator (42) is supplied to the heating assembly (32) of the water assembly (3) to replace at least part of the extraction steam of the heating assembly (32) from the high-pressure cylinder (11) and the intermediate-pressure cylinder (12) of the steam turbine (1); comprising the following steps: First, the steam generated by the high-pressure steam accumulator (42) replaces the extraction steam of the heating assembly (32) from the high-pressure cylinder (11); Then, the steam generated by the high-pressure steam accumulator (42) replaces the extraction steam of the heating assembly (32) from the intermediate-pressure cylinder (12).

10. The peak shaving method of claim 8, wherein, Further comprising the following steps: When the unit is being reduced in load, the total flow of main steam delivered to and stored in the high-pressure steam accumulator (42) and / or the low-pressure steam accumulator (43) is adjusted to regulate the rate of load reduction of the unit; When the unit is being increased in load, the flow of steam delivered by the high-pressure steam accumulator (42) to the heating assembly (32) is adjusted, and / or the flow of steam delivered by the low-pressure steam accumulator (43) to the low-pressure cylinder (13) and / or the heating assembly (32) is adjusted, to regulate the rate of load increase of the unit.

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