CN212003284U

CN212003284U - Fused salt step storage energy peak regulation system of thermal power generating unit

Info

Publication number: CN212003284U
Application number: CN202020204911.7U
Authority: CN
Inventors: 夏云飞; 叶勇健; 林磊; 蒋健; 邓文祥; 姚向昱
Original assignee: China Power Engineering Consulting Group East China Electric Power Design Institute Co Ltd
Current assignee: China Power Engineering Consulting Group East China Electric Power Design Institute Co Ltd
Priority date: 2020-02-25
Filing date: 2020-02-25
Publication date: 2020-11-24
Anticipated expiration: 2030-02-25

Abstract

The utility model relates to the technical field of fused salt storage tanks, in particular to a fused salt step storage and peak regulation system of a thermal power generating unit, which comprises the thermal power generating unit and the fused salt step storage and peak regulation system, wherein the thermal power generating unit comprises a boiler, a main turbine, a condenser, a condensate pump, a water feeding pump, a heat recovery system, a small turbine of the water feeding pump, an auxiliary steam pipeline, a small turbine of an induced draft fan and a smoke and air system; the molten salt cascade energy storage and release system comprises a high-temperature steam-molten salt heat exchanger group, a low-temperature steam-molten salt heat exchanger group, a high-temperature molten salt-steam heat exchanger group, a low-temperature molten salt-steam heat exchanger group, a high-temperature hot-melt salt tank, a low-temperature hot-melt salt tank and a cold-melt salt tank. The utility model discloses can improve energy utilization, save cost, the system is complete, and the reliability is high, has the flexibility, and the security is high.

Description

Fused salt step storage energy peak regulation system of thermal power generating unit

Technical Field

The utility model relates to a fused salt energy storage technical field, in particular to fused salt step of thermal power generating unit stores can peak shaving system.

Background

The energy revolution aims to promote the sustainable development of energy, promote the development of new energy and the clean and efficient utilization of fossil energy. The rapid increase of new energy forces the load rate of the traditional thermal power generating units to be reduced, most units run in a non-full load state for a long time, and a few units even stop working, so that the waste of the produced resources is caused; meanwhile, the increasingly expanded peak-valley power utilization difference is combined with the reduction of the whole load requirement of the thermal power generating unit, so that the load of the unit is further reduced in the valley power time period, and the lowest steady load of the thermal power generating unit is directly approached. The changes result in low utilization rate of the produced thermal power generating units, low power generation efficiency, increased emission of equivalent pollutants, greatly reduced safety reliability and economy, and do not conform to the aim of sustainable development of energy revolution. Therefore, the development of new deep peak shaving systems and techniques is urgent.

The energy storage technology can play an important role in the field of deep peak regulation and is one of the cores of sustainable energy development. The peak regulation system is applied to a peak regulation system of a thermal power generating unit, so that the lowest load of the unit can be greatly improved; the heating capacity of the unit during high load can be enhanced, or the electric quantity supply of the power grid during high load demand can be further ensured. Therefore, the energy storage technology is applied to the thermal power generating unit, the utilization rate of the unit equipment, the generating efficiency, the safety reliability and the economy are favorably improved, the pollutant emission is reduced, and the purpose of sustainable development of the energy revolution is met.

The fused salt energy storage power supply and heat supply technology is commercially applied, and has the advantages of mature technology and relatively low cost if being successfully applied to a solar thermal power generation station. The method is applied to thermal power generating units to participate in peak regulation power supply and heat supply, and is technically and economically feasible.

At present, a molten salt energy storage technology is applied to the technical scheme in the field of power generation, namely, electricity abandoned by photovoltaic and wind power is utilized to heat molten salt, and heat stored by the molten salt is used for heating working media such as steam or helium to drive a turbine to generate power when needed. The technical scheme can be transplanted to the field of thermal power generation to participate in deep peak regulation, but the efficiency is only about 15 percent due to the electricity, heat and electricity conversion process and the primary heat exchange process, and the economical efficiency is poor; in addition, the present technique of being applied to thermal power field with the fused salt energy storage is the single-stage utilization of fused salt energy storage, follows the indirect or direct heat absorption storage of thermal power unit steam-water system in the fused salt promptly, and the fused salt is exothermic to the unit user that consumes heat or to the energy storage steam turbine electricity generation that new casing was built or to the heating system heat supply when needing, and this technical scheme compares with the above-mentioned electricity, heat, the technical scheme of circuit line, and the economic nature promotes to some extent, but this technical scheme has obvious shortcoming: firstly, high-parameter steam (up to 550 ℃) heated by high-temperature hot-melt salt directly heats working media with lower parameters, such as working media at the cold end of a heat supply network, auxiliary steam for shaft seal, primary air and secondary air of a boiler and the like, the heat transfer temperature difference is large, and the loss is large; secondly, the investment of building a steam turbine for energy storage by a new matching sleeve is large; and the freezing point of the molten salt is higher, if the light and heat power station keeps the binary molten salt flowing, the temperature of the cold end of the molten salt is required to be higher than 280 ℃, so that the parameters are still higher (the temperature can reach more than 300 ℃) after the steam extracted from the unit steam-water system releases heat to the molten salt, and the high energy value is still not utilized.

Therefore, under the background that the whole-grid thermal power generating unit participates in peak shaving, in order to solve the problem of low-load and even lowest stable load operation of the thermal power generating unit caused by low-load requirement and peak-valley difference of a power grid, a more efficient fused salt energy storage peak shaving power supply and heat supply system coupled with the thermal power generating unit needs to be developed urgently.

SUMMERY OF THE UTILITY MODEL

The utility model provides a fused salt energy storage system be the single-stage utilization among the correlation technique and cause the great problem of energy loss, provide a thermal power generating unit fused salt step and store ability peak shaving system.

In order to solve the technical problem, the utility model discloses a realize through following technical scheme: the utility model provides a fused salt step stores can peak shaving system of thermal power generating unit, includes:

the system comprises a thermal power generating unit, a heat pump, a heat recovery system, a steam generator, a steam turbine, a steam pipeline, a heat recovery system, a steam pump, a steam turbine, a heat recovery system and a heat recovery system, wherein the boiler is connected with the main steam turbine through the steam; the main steam turbine is connected with the heat recovery system, and part of steam is pumped to the heat recovery system for cyclic utilization; the boiler is connected with a heat recovery system through a water supply pipeline, and is connected with a smoke and air system through a primary air duct, an air supply duct and a flue;

the molten salt stepped energy storage and release system comprises a high-temperature steam-molten salt heat exchanger group, a low-temperature steam-molten salt heat exchanger group, a high-temperature molten salt-steam heat exchanger group, a low-temperature molten salt-steam heat exchanger group, a high-temperature hot-melt salt tank, a low-temperature hot-melt salt tank and a cold-melt salt tank;

the molten salt side of the high-temperature steam-molten salt heat exchanger group is connected with the high-temperature hot-melt salt tank, the low-temperature hot-melt salt tank and the cold-melt salt tank; the steam side of the high-temperature steam-molten salt heat exchanger group is connected with a steam pipeline from the boiler to the main steam turbine, a heat regeneration system, an auxiliary steam pipeline, a heat supply system and a smoke and air system, the heat of the steam from the boiler to the steam pipeline of the main steam turbine is released to cold molten salt pumped out from a cold molten salt tank, so that the cold molten salt becomes hot molten salt, the hot molten salt is stored in the high-temperature hot molten salt tank and the low-temperature hot molten salt tank according to the temperature gradient of the hot molten salt, and the steam after heat release is used for the heat regeneration system, the auxiliary steam pipeline, the heat supply system and the smoke and air system according to the;

the molten salt side of the low-temperature steam-molten salt heat exchanger group is connected with the low-temperature hot molten salt tank and the cold molten salt tank; the steam side of the low-temperature steam-molten salt heat exchanger group is connected with a steam pipeline from a main steam turbine to a boiler, a steam extraction pipeline of the main steam turbine, a heat recovery system, an auxiliary steam pipeline, a heat supply system and a smoke and air system, the heat of the steam from the main steam turbine to the steam pipeline of the boiler or the steam extraction pipeline of the main steam turbine is released to cold molten salt pumped out from a cold molten salt tank, the cold molten salt becomes low-temperature hot molten salt and is stored in the low-temperature hot molten salt tank, and the steam after heat release is used for the heat recovery system, the auxiliary steam pipeline, the heat supply system and the smoke and air system according to the parameter characteristic steps;

the molten salt side of the high-temperature molten salt-steam heat exchanger group is connected with a high-temperature hot-melt salt tank, a low-temperature hot-melt salt tank and a cold-melt salt tank; the steam side of the high-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of a main steam turbine, a heat recovery system, a heat supply system, a small steam turbine of a water supply pump and a small steam turbine of an induced draft fan, the heat stored by the high-temperature and high-temperature molten salt in the high-temperature molten salt tank is released to the steam from the steam extraction pipeline of the main steam turbine, the parameters of the steam are improved, the steam is used for the heat recovery system, the heat supply system, the small steam turbine of the water supply pump and the small steam turbine of the induced draft fan according to the parameter characteristic steps, and the heat released molten salt is stored;

the molten salt side of the low-temperature molten salt-steam heat exchanger group is connected with the low-temperature hot molten salt tank and the cold molten salt tank; the low-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of the main steam turbine, a heat regeneration system, a heat supply system, an auxiliary steam pipeline and a smoke and air system on the steam side, releases heat stored in low-temperature and high-temperature molten salt in the low-temperature molten salt tank to steam coming from the steam extraction pipeline of the main steam turbine, improves parameters of the low-temperature and high-temperature molten salt, is used for the heat regeneration system, the heat supply system, the auxiliary steam pipeline and the smoke and air system according to parameter characteristic steps, and stores the released molten salt in the cold molten salt tank.

As a preferred scheme, the high-temperature steam-molten salt heat exchanger group can be one heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the low-temperature steam-molten salt heat exchanger group can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the high-temperature molten salt-steam heat exchanger group can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the low-temperature molten salt-steam heat exchanger group can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel.

As a preferred scheme, the heat recovery system comprises a low-pressure heater module, a deaerator and a high-pressure heater module which are sequentially connected, and a condenser and a condensate pump are sequentially connected between the main turbine and the low-pressure heater module; a water feeding pump is connected between the deaerator and the high-pressure heater module, the water feeding pump is driven by a small steam turbine of the water feeding pump, and the small steam turbine of the water feeding pump is connected with the steam side of the high-temperature molten salt-steam heat exchanger group; the high-pressure heater module is connected with an economizer of the boiler through a water feeding pipeline, and the low-pressure heater module and the deaerator are respectively connected with the steam sides of the high-temperature steam-molten salt heat exchanger group and the low-temperature steam-molten salt heat exchanger group; the high-pressure heater module is respectively connected with the steam sides of the high-temperature steam-molten salt heat exchanger group, the low-temperature steam-molten salt heat exchanger group, the high-temperature molten salt-steam heat exchanger group and the low-temperature molten salt-steam heat exchanger group.

As a preferred scheme, the smoke and air system comprises a smoke system and an air system, wherein the smoke system is sequentially connected with a dust remover, an induced draft fan, a desulfurizing tower, a smoke heater and a chimney through a flue from an air preheater of a boiler, the induced draft fan is driven by a small turbine of the induced draft fan, and the small turbine of the induced draft fan is connected with the steam side of the high-temperature molten salt-steam heat exchanger group; the air system comprises a primary air heater, an air supply heater, a primary air fan and an air feeder, wherein the primary air fan and the air feeder are respectively connected with the primary air heater through a primary air channel and an air supply channel and then connected with the boiler through the primary air channel and the air supply channel, and the primary air heater, the air supply heater and the flue gas heater are respectively connected with the high-temperature steam-molten salt heat exchanger group, the low-temperature steam-molten salt heat exchanger group and the low-temperature molten salt-steam heat exchanger group on the steam side.

Preferably, the thermal power generating unit comprises a non-reheating unit, a primary reheating unit and a secondary reheating unit.

Preferably, when the thermal power generating unit is a reheat-free unit, the main turbine comprises a main turbine high-pressure cylinder and a main turbine low-pressure cylinder, and the main turbine high-pressure cylinder is connected with a superheater of a boiler through a main steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group is connected with the main steam pipeline, and heat of the steam from the main steam pipeline is released to cold molten salt pumped out from the cold molten salt tank; the steam side of the low-temperature steam-molten salt heat exchanger group is connected with a steam extraction pipeline of a main steam turbine high-pressure cylinder, and heat of steam in the steam extraction pipeline of the main steam turbine high-pressure cylinder is released to cold molten salt pumped out from a cold molten salt tank; the steam side of the high-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of a low-pressure cylinder of the main steam turbine, and heat stored by high-temperature and high-temperature molten salt in the high-temperature molten salt tank is released to steam from the steam extraction pipeline of the low-pressure cylinder of the main steam turbine; the steam side of the low-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of a low-pressure cylinder of the main steam turbine, and heat stored by low-temperature and high-temperature molten salt in the low-temperature molten salt tank is released to steam from the steam extraction pipeline of the low-pressure cylinder of the main steam turbine; and the low-pressure cylinder of the main turbine is connected with the condenser.

Preferably, when the thermal power generating unit is a primary reheating unit, the main turbine comprises a main turbine high-pressure cylinder, a main turbine intermediate-pressure cylinder and a main turbine low-pressure cylinder, and the main turbine high-pressure cylinder is connected with a superheater and a primary reheater of a boiler through a main steam pipeline and a low-temperature reheating steam pipeline respectively; the primary reheater is then connected with a main turbine intermediate pressure cylinder through a high-temperature reheating steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group is connected with the main steam pipeline and the high-temperature reheating steam pipeline, and the heat of the steam from the main steam pipeline or the high-temperature reheating steam pipeline is released to cold molten salt pumped out from the cold molten salt tank; the steam side of the low-temperature steam-molten salt heat exchanger group is connected with a low-temperature reheating steam pipeline and a steam extraction pipeline of a main steam turbine high-pressure cylinder, and heat of steam from the low-temperature reheating steam pipeline or the steam extraction pipeline of the main steam turbine high-pressure cylinder is released to cold molten salt pumped out from a cold molten salt tank; the steam side of the high-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder and a steam extraction pipeline of a main steam turbine low pressure cylinder, and heat stored by high-temperature molten salt in the high-temperature molten salt tank is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder or the steam extraction pipeline of the main steam turbine low pressure cylinder; the steam side of the low-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder and a steam extraction pipeline of a main steam turbine low pressure cylinder, and heat stored by low-temperature hot molten salt in the low-temperature hot molten salt tank is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder or the steam extraction pipeline of the main steam turbine low pressure cylinder; and the low-pressure cylinder of the main turbine is connected with the condenser.

Preferably, when the thermal power generating unit is a secondary reheating unit, the main turbine comprises a main turbine ultrahigh pressure cylinder, a main turbine high pressure cylinder, a main turbine intermediate pressure cylinder and a main turbine low pressure cylinder, and the main turbine ultrahigh pressure cylinder is connected with a superheater and a primary reheater of the boiler through a main steam pipeline and a primary low-temperature reheat steam pipeline respectively; the main turbine high-pressure cylinder is respectively connected with a primary reheater and a secondary reheater of the boiler through a primary high-temperature reheated steam pipeline and a secondary low-temperature reheated steam pipeline; the main turbine intermediate pressure cylinder is connected with a secondary reheater of the boiler through a secondary high-temperature reheating steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group is connected with a main steam pipeline, a primary high-temperature reheating steam pipeline and a secondary high-temperature reheating steam pipeline, and the heat of the steam from the main steam pipeline or the primary high-temperature reheating steam pipeline or the secondary high-temperature reheating steam pipeline is released to cold molten salt pumped out from a cold molten salt tank; the steam side of the low-temperature steam-molten salt heat exchanger group is connected with a primary low-temperature reheating steam pipeline, a secondary low-temperature reheating steam pipeline and a main steam turbine high-pressure cylinder steam extraction pipeline, and heat of steam from the primary low-temperature reheating steam pipeline or the secondary low-temperature reheating steam pipeline or the main steam turbine high-pressure cylinder steam extraction pipeline is released to cold molten salt pumped out from a cold molten salt tank; the steam side of the high-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder and a steam extraction pipeline of a main steam turbine low pressure cylinder, and heat stored by high-temperature and high-temperature molten salt in the high-temperature molten salt tank is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder or the steam extraction pipeline of the main steam turbine low pressure cylinder; the steam side of the low-temperature molten salt-steam heat exchanger group is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder and a steam extraction pipeline of a main steam turbine low-temperature pressure cylinder, and heat stored in low-temperature hot molten salt in the low-temperature hot molten salt tank is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder or the steam extraction pipeline of the main steam turbine low-temperature pressure cylinder; and the low-pressure cylinder of the main turbine is connected with the condenser.

Compared with the prior art, the beneficial effects of the utility model are that:

(1) when the thermal power generating unit runs at low or extremely low load caused by deep peak load regulation or peak-valley difference of a power grid, the load of the thermal power generating unit is properly increased, the heat left after meeting the power supply and heat supply requirements is stored in high and low temperature hot-melt salt tanks in a gradient manner, and when the load of the power grid and the heat supply load are high, the stored heat is released in a gradient manner for utilization, so that the utilization rate of equipment, the power generation efficiency, the safety and reliability and the economy can be improved, and the emission of equivalent pollutants is reduced; furthermore, the load of the unit is higher than the minimum stable combustion load for a long time, potential safety hazards are eliminated, the unit is not required to be transformed by reducing the minimum stable combustion load due to deep peak shaving of the power grid, and investment is saved.

(2) Compare existing thermal power generating unit energy storage technique, step energy storage and the step utilization of storing energy can make the whole system reach higher efficiency, the utility model discloses be equipped with two fused salt heat storage tanks of high temperature, low temperature, each correspond one set fill, heat exchanger group releases, can carry out the heat of the steam of the different parameters of thermal power generating unit preferred step storage as required, when the fused salt was released heat, also can utilize the heat of storage according to the user with vapour parameter demand step, reduce the poor loss of heat transfer end.

(3) The fused salt freezing point is high, and the temperature that maintains fused salt work needs is higher, and thermal power unit steam still has very high parameter after giving the fused salt with the heat step release, the utility model discloses a system utilizes the steam after releasing heat, avoids the loss to with the principle that the step utilized, make energy utilization efficiency maximize.

(4) The utility model has the advantages that the high-parameter steam for energy storage and the low-parameter steam heated by the fused salt are selected from a plurality of sources, including main steam, reheat steam and steam extraction of a main steam turbine; the users of the steam after releasing heat to molten salt and the steam heated by the molten salt are more, and the steam comprises a heat return system, a smoke wind system, an auxiliary steam system, a heat supply system and the like; the energy storage system cannot be shut down or even the safety of the energy storage system cannot be influenced due to the fault of a certain source or a user system when the heat is stored in a cascade mode and used; multiple sources and multiple users can be selected according to the requirements during engineering design. The utility model discloses the system is complete, and the reliability is high, and has the flexibility, and simultaneously, each user also obtains great promotion because of energy storage system's access, operation fail safe nature.

(5) The utility model adopts the scheme of two hot molten salt tanks at high temperature and low temperature and one cold molten salt tank, compared with the scheme of only one hot molten salt tank, the volume capacity of the two hot molten salt tanks at high temperature and low temperature can be properly reduced, and the safety is improved; meanwhile, according to the concept of step energy storage, the design temperature of the low-temperature hot-melt salt tank does not need to reach the design temperature of the high-temperature hot-melt salt tank such as 580 ℃, the design temperature can be lower than 400 ℃, the materials do not need to adopt stainless steel adopted by the high-temperature hot-melt salt tank, and carbon steel can be adopted, so that the safety is further improved, and the investment is saved.

Drawings

FIG. 1 shows a fused salt gradient energy storage and release peak regulation system of a non-reheat thermal power generating unit in an embodiment 1 of the invention;

FIG. 2 is an embodiment 2 of the present invention, a molten salt stepped energy storage and peak shaving system for a single reheat thermal power generating unit;

FIG. 3 is an embodiment 3 of the utility model discloses a fused salt step stores can peak shaving system of twice reheat thermal power generating unit.

In the figure:

1. a high-temperature steam-molten salt heat exchanger group, 2, a low-temperature steam-molten salt heat exchanger group, 3, a high-temperature molten salt-steam heat exchanger group, 4, a low-temperature molten salt-steam heat exchanger group, 5, a high-temperature molten salt tank, 5a, a high-temperature molten salt pump, 6, a low-temperature molten salt tank, 6a, a low-temperature molten salt pump, 7, a cold molten salt tank, 7a, a cold molten salt pump I, 7b, a cold molten salt pump II, 8, a boiler, 9, a main turbine ultrahigh pressure cylinder, 10, a main turbine high pressure cylinder, 11, a main turbine intermediate pressure cylinder, 12, a main turbine low pressure cylinder, 13, a condenser, 14, a condensate pump, 15, a low-pressure heater module, 16, a deaerator, 17, a water supply pump small turbine, 18, a high-pressure heater module, 19, a water supply pump, 20, an auxiliary steam pipeline, 21, a heat supply system, 22, a coal economizer, 23, a water cooling, 25. the system comprises a primary reheater, a secondary reheater, a primary air heater, a primary air supply heater, a primary fan, a blower 31, an air preheater, a dust remover, a draught fan small turbine 33, a draught fan small turbine 34, a draught fan 35, a desulfurizing tower 36, a flue gas heater 37 and a chimney 28.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.

Example 1

The thermal power generating unit in this embodiment is a non-reheat unit.

As shown in FIG. 1, the fused salt stepped energy storage and peak regulation system for the thermal power generating unit comprises the thermal power generating unit and the fused salt stepped energy storage and release system.

The thermal power generating unit comprises a boiler 8, a main steam turbine, a condenser 13, a condensate pump 14, a water feeding pump 19, a heat return system, a small water feeding pump turbine 17, an auxiliary steam pipeline 20, a small induced draft fan turbine 33 and a smoke and air system, wherein the boiler 8 is connected with the main steam turbine through a steam pipeline, outputs main steam to the main steam turbine, heats low-temperature reheat steam from the main steam turbine to high-temperature reheat steam and then returns the low-temperature reheat steam to the main steam turbine; the main steam turbine is connected with the heat recovery system, and part of steam is pumped to the heat recovery system for cyclic utilization; the boiler 8 is connected with a regenerative system through a water supply pipeline, and the boiler 8 is connected with a smoke and air system through a primary air duct, an air supply duct and a flue;

the molten salt stepped energy storage and release system comprises a high-temperature steam-molten salt heat exchanger group 1, a low-temperature steam-molten salt heat exchanger group 2, a high-temperature molten salt-steam heat exchanger group 3, a low-temperature molten salt-steam heat exchanger group 4, a high-temperature hot-molten salt tank 5, a low-temperature hot-molten salt tank 6 and a cold-molten salt tank 7, wherein a high-temperature hot-molten salt pump 5a is arranged on the high-temperature hot-molten salt tank 5, a low-temperature hot-molten salt pump 6a is arranged on the low-temperature hot-molten salt tank 6, and a cold-molten salt pump I7 a and a cold-molten salt pump II 7b are arranged on the cold-molten salt tank 7 and used for pumping out molten.

Wherein the molten salt side of the high-temperature steam-molten salt heat exchanger group 1 is connected with a high-temperature hot-melt salt tank 5, a low-temperature hot-melt salt tank 6 and a cold-melt salt tank 7; the steam side of the high-temperature steam-molten salt heat exchanger group 1 is connected with a steam pipeline from a boiler 8 to a main steam turbine, a regenerative system, an auxiliary steam pipeline 20, a heat supply system 21 and a smoke and air system, heat of steam from the boiler 8 to the steam pipeline of the main steam turbine is released to cold molten salt pumped out from a cold molten salt tank 7 to be hot molten salt, the cold molten salt is stored in a high-temperature hot molten salt tank 5 and a low-temperature hot molten salt tank 6 according to the temperature gradient of the hot molten salt, and the steam after heat release is used for the regenerative system, the auxiliary steam pipeline 20, the heat supply system 21 and the smoke and air system according to the parameter (mainly temperature) characteristic gradient of the steam;

wherein the molten salt side of the low-temperature steam-molten salt heat exchanger group 2 is connected with a low-temperature hot molten salt tank 6 and a cold molten salt tank 7; the steam side of the low-temperature steam-molten salt heat exchanger group 2 is connected with a steam pipeline from a main steam turbine to a boiler 8, a steam extraction pipeline of the main steam turbine, a regenerative system, an auxiliary steam pipeline 20, a heat supply system 21 and a smoke and air system, the heat of the steam from the main steam turbine to the steam pipeline of the boiler 8 or the steam extraction pipeline of the main steam turbine is released to cold molten salt pumped out from a cold molten salt tank 7 to be low-temperature hot molten salt, the cold molten salt is stored in a low-temperature hot molten salt tank 6, and the released steam is used for the regenerative system, the auxiliary steam pipeline 20, the heat supply system 21 and the smoke and air system according to the parameter characteristics of the steam;

wherein, the molten salt side of the high-temperature molten salt-steam heat exchanger group 3 is connected with a high-temperature hot molten salt tank 5, a low-temperature hot molten salt tank 6 and a cold molten salt tank 7; the steam side of the high-temperature molten salt-steam heat exchanger group 3 is connected with a main steam turbine steam extraction pipeline, a heat return system, a heat supply system 21, a water supply pump small steam turbine 17 and an induced draft fan small steam turbine 33, heat stored by high-temperature and high-temperature molten salt in the high-temperature molten salt tank 5 is released to steam from the main steam turbine steam extraction pipeline, parameters of the steam are improved, the heat is used for the heat return system, the heat supply system 21, the water supply pump small steam turbine 17 and the induced draft fan small steam turbine 33 according to parameter characteristic steps, and the released molten salt is stored in the low-temperature molten salt tank 6 or the cold molten salt tank 7 according to temperature steps;

wherein, the molten salt side of the low-temperature molten salt-steam heat exchanger group 4 is connected with a low-temperature molten salt tank 6 and a cold molten salt tank 7; the steam side of the low-temperature molten salt-steam heat exchanger group 4 is connected with a main steam turbine steam extraction pipeline, a heat return system, a heat supply system 21, an auxiliary steam pipeline 20 and a smoke and air system, heat stored in low-temperature molten salt in the low-temperature molten salt tank 6 is released to steam from the main steam turbine steam extraction pipeline, parameters of the steam are improved, the steam is used for the heat return system, the heat supply system 21, the auxiliary steam pipeline 20 and the smoke and air system according to parameter characteristic steps, and the molten salt after heat release is stored in the cold molten salt tank 7.

In one embodiment, the high-temperature steam-molten salt heat exchanger group 1 can be a heat exchanger, or a plurality of heat exchangers connected in series or in parallel according to actual needs; the low-temperature steam-molten salt heat exchanger group 2 can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the high-temperature molten salt-steam heat exchanger group 3 can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the low-temperature molten salt-steam heat exchanger group 4 can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel.

In one embodiment, the regenerative system comprises a low-pressure heater module 15, a deaerator 16 and a high-pressure heater module 18 which are connected in sequence, and a condenser 13 and a condensate pump 14 are connected between a main turbine and the low-pressure heater module 15 in sequence; a water feeding pump 19 is connected between the deaerator 16 and the high-pressure heater module 18, the water feeding pump 19 is driven by a small water feeding pump turbine 17, and the small water feeding pump turbine 17 is connected with the steam side of the high-temperature molten salt-steam heat exchanger group 3; the high-pressure heater module 18 is connected with an economizer 22 of the boiler 8 through a water feeding pipeline, and the low-pressure heater module 15 and the deaerator 16 are respectively connected with the steam sides of the high-temperature steam-molten salt heat exchanger group 1 and the low-temperature steam-molten salt heat exchanger group 2; the high-pressure heater module 18 is respectively connected with the steam sides of the high-temperature steam-molten salt heat exchanger group 1, the low-temperature steam-molten salt heat exchanger group 2, the high-temperature molten salt-steam heat exchanger group 3 and the low-temperature molten salt-steam heat exchanger group 4.

In one embodiment, the flue gas and air system comprises a flue gas system and an air system, the flue gas system is sequentially connected with a dust remover 32, an induced draft fan 34, a desulfurizing tower 35, a flue gas heater 36 and a chimney 37 from an air preheater 31 of the boiler 8 through a flue, the induced draft fan 34 is driven by an induced draft fan small turbine 33, and the induced draft fan small turbine 33 is connected with the steam side of the high-temperature molten salt-steam heat exchanger group 3; the air system comprises a primary air heater 27, an air supply heater 28, a primary air fan 29 and an air supply blower 30, wherein the primary air fan 29 and the air supply blower 30 are respectively connected with the primary air heater 27 and the air supply heater 28 through a primary air duct and an air supply duct, and then are connected with the boiler 8 through the primary air duct and the air supply duct, and the primary air heater 27, the air supply heater 28 and the flue gas heater 36 are respectively connected with the steam sides of the high-temperature steam-molten salt heat exchanger group 1, the low-temperature steam-molten salt heat exchanger group 2 and the low-temperature molten salt-steam heat exchanger group 4.

In the embodiment, the thermal power generating unit is a reheat-free unit, the main turbine comprises a main turbine high-pressure cylinder 10 and a main turbine low-pressure cylinder 12, and the main turbine high-pressure cylinder 10 is connected with a superheater 24 of the boiler 8 through a main steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group 1 is connected with a main steam pipeline, and heat of steam from the main steam pipeline is released to cold molten salt pumped out from a cold molten salt tank 7; the steam side of the low-temperature steam-molten salt heat exchanger group 2 is connected with a steam extraction pipeline of the main steam turbine high-pressure cylinder 10, and heat of steam in the steam extraction pipeline of the main steam turbine high-pressure cylinder 10 is released to cold molten salt pumped out from the cold molten salt tank 7; the steam side of the high-temperature molten salt-steam heat exchanger group 3 is connected with a steam extraction pipeline of the main steam turbine low-pressure cylinder 12, and the heat stored by the high-temperature molten salt in the high-temperature molten salt tank 5 is released to the steam from the steam extraction pipeline of the main steam turbine low-pressure cylinder 12; the steam side of the low-temperature molten salt-steam heat exchanger group 4 is connected with a steam extraction pipeline of the main steam turbine low-pressure cylinder 12, and the heat stored by the low-temperature hot molten salt in the low-temperature hot molten salt tank 6 is released to the steam from the steam extraction pipeline of the main steam turbine low-pressure cylinder 12; the main turbine low-pressure cylinder 12 is connected to a condenser 13.

When the non-reheat thermal power generating unit works independently, the boiler 8 generates main steam to the main turbine high-pressure cylinder 10 to do work, the steam discharged from the main turbine high-pressure cylinder 10 enters the main turbine low-pressure cylinder 12 to do work and then is discharged to the condenser 13 to be condensed into water, then the condensed water in the condenser 13 is pumped out by the condensed water pump 14, is heated by the low-pressure heater module 15 and the deaerator 16, is pressurized by the water feeding pump 19, is reheated by the high-pressure heater module 18 and then is sent to the economizer 22 of the boiler 8; the primary air blower 29 and the air blower 30 supply air for conveying and burning out the pulverized coal combustion of the boiler 8, and the primary air heater 27 and the air supply heater 28 are used for preheating the primary air and supplying air; the flue gas heater 36 is used to heat the flue gas to increase the temperature of the flue gas (white elimination).

Example 2

The thermal power generating unit in this embodiment is a single reheating unit.

As shown in FIG. 2, the thermal power generating unit molten salt stepped energy storage and peak regulation system comprises a thermal power generating unit and a molten salt stepped energy storage and release system.

In this embodiment, the thermal power generating unit is a primary reheating unit, the main turbine includes a main turbine high-pressure cylinder 10, a main turbine intermediate-pressure cylinder 11 and a main turbine low-pressure cylinder 12, and the main turbine high-pressure cylinder 10 is connected to a superheater 24 and a primary reheater 25 of the boiler 8 through a main steam pipeline and a low-temperature reheat steam pipeline, respectively; the primary reheater 25 is connected to the main turbine intermediate pressure cylinder 11 through a high-temperature reheat steam line; the steam side of the high-temperature steam-molten salt heat exchanger group 1 is connected with a main steam pipeline and a high-temperature reheating steam pipeline, and heat of steam from the main steam pipeline or the high-temperature reheating steam pipeline is released to cold molten salt pumped out from a cold molten salt tank 7; the steam side of the low-temperature steam-molten salt heat exchanger group 2 is connected with a low-temperature reheating steam pipeline and a steam extraction pipeline of the main steam turbine high-pressure cylinder 10, and heat of steam from the low-temperature reheating steam pipeline or the steam extraction pipeline of the main steam turbine high-pressure cylinder 10 is released to cold molten salt pumped out from the cold molten salt tank 7; the steam side of the high-temperature molten salt-steam heat exchanger group 3 is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder 11 and a steam extraction pipeline of a main steam turbine low pressure cylinder 12, and heat stored by high-temperature molten salt in the high-temperature molten salt tank 5 is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder 11 or the steam extraction pipeline of the main steam turbine low pressure cylinder 12; the steam side of the low-temperature molten salt-steam heat exchanger group 4 is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder 11 and a steam extraction pipeline of a main steam turbine low pressure cylinder 12, and heat stored in low-temperature hot molten salt in the low-temperature hot molten salt tank 6 is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder 11 or the steam extraction pipeline of the main steam turbine low pressure cylinder 12; the main turbine low-pressure cylinder 12 is connected to a condenser 13.

When the primary reheat thermal power generating unit works independently, the boiler 8 generates main steam to the main turbine high-pressure cylinder 10 to do work, the exhaust gas of the main turbine high-pressure cylinder 10 enters the primary reheater 25 of the boiler 8 to absorb heat and then enters the main turbine intermediate-pressure cylinder 11 to continue to do work, the exhaust gas of the main turbine intermediate-pressure cylinder 11 enters the main turbine low-pressure cylinder 12 to do work and then is discharged to the condenser 13 to be condensed into water, then the condensed water in the condenser 13 is pumped out by the condensed water pump 14, heated by the low-pressure heater module 15 and the deaerator 16, pressurized by the water feed pump 19 and reheated by the high-pressure heater module 18 and then sent to the economizer 22 of the boiler 8; the primary air blower 29 and the air blower 30 supply air for conveying and burning out the pulverized coal combustion of the boiler 8, and the primary air heater 27 and the air supply heater 28 are used for preheating the primary air and supplying air; the flue gas heater 36 is used to heat the flue gas to increase the temperature of the flue gas (white elimination).

Example 3

In this embodiment, the thermal power generating unit is a secondary reheating unit.

As shown in fig. 3, the thermal power generating unit molten salt stepped energy storage and peak regulation system comprises a thermal power generating unit and a molten salt stepped energy storage and release system.

In this embodiment, the thermal power generating unit is a secondary reheating unit, the main turbine includes a main turbine ultrahigh pressure cylinder 9, a main turbine high pressure cylinder 10, a main turbine intermediate pressure cylinder 11 and a main turbine low pressure cylinder 12, and the main turbine ultrahigh pressure cylinder 9 is connected to a superheater 24 and a primary reheater 25 of the boiler 8 through a main steam pipeline and a primary low-temperature reheat steam pipeline, respectively; the main turbine high-pressure cylinder 10 is connected with a primary reheater 25 and a secondary reheater 26 of the boiler 8 through a primary high-temperature reheat steam pipeline and a secondary low-temperature reheat steam pipeline respectively; the main turbine intermediate pressure cylinder 11 is connected with a secondary reheater 26 of the boiler 8 through a secondary high-temperature reheat steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group 1 is connected with a main steam pipeline, a primary high-temperature reheating steam pipeline and a secondary high-temperature reheating steam pipeline, and the heat of the steam from the main steam pipeline or the primary high-temperature reheating steam pipeline or the secondary high-temperature reheating steam pipeline is released to cold molten salt pumped out from a cold molten salt tank 7; the steam side of the low-temperature steam-molten salt heat exchanger group 2 is connected with a primary low-temperature reheating steam pipeline, a secondary low-temperature reheating steam pipeline and a main steam turbine high-pressure cylinder 10 steam extraction pipeline, and the heat of the steam from the primary low-temperature reheating steam pipeline or the secondary low-temperature reheating steam pipeline or the main steam turbine high-pressure cylinder 10 steam extraction pipeline is released to the cold molten salt pumped out from the cold molten salt tank 7; the steam side of the high-temperature molten salt-steam heat exchanger group 3 is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder 11 and a steam extraction pipeline of a main steam turbine low pressure cylinder 12, and heat stored by high-temperature molten salt in the high-temperature molten salt tank 5 is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder 11 or the steam extraction pipeline of the main steam turbine low pressure cylinder 12; the steam side of the low-temperature molten salt-steam heat exchanger group 4 is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder 11 and a steam extraction pipeline of a main steam turbine low pressure cylinder 12, and heat stored by low-temperature hot molten salt in the low-temperature hot molten salt tank 6 is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder 11 or the steam extraction pipeline of the main steam turbine low pressure cylinder 12; the main turbine low-pressure cylinder 12 is connected to a condenser 13.

When the secondary reheat thermal power generating unit works independently, the boiler 8 generates main steam to the main turbine ultrahigh pressure cylinder 9 to do work, the exhaust gas of the main turbine ultrahigh pressure cylinder 9 enters a primary reheater 25 of the boiler 8 to absorb heat and then continues to do work to the main turbine high pressure cylinder 10, the exhaust gas of the main turbine high pressure cylinder 10 enters a secondary reheater 26 of the boiler 8 to absorb heat and then continues to do work to the main turbine intermediate pressure cylinder 11, the exhaust gas of the main turbine intermediate pressure cylinder 11 enters a main turbine low pressure cylinder 12 to do work and then is discharged to the condenser 13 to be condensed into water, then the condensed water in the condenser 13 is extracted by the condensed water pump 14, and after being heated by the low-pressure heater module 15 and the deaerator 16, the condensed water is pressurized by the water feed pump 19 and is reheated by the high-pressure heater module 18 and then is sent to the; the primary air blower 29 and the air blower 30 supply air for conveying and burning out the pulverized coal combustion of the boiler 8, and the primary air heater 27 and the air supply heater 28 are used for preheating the primary air and supplying air; the flue gas heater 36 is used to heat the flue gas to increase the temperature of the flue gas (white elimination).

In addition, for the thermal power generating units without reheating, with single reheating and with double reheating, the fuel can be selected from coal, oil, gas, biomass, garbage, sludge and the like.

The principle of the method for supplying power and heat by adopting the fused salt cascade energy storage and peak regulation system of the thermal power generating unit is as follows:

a1. when the peak load regulation or peak-valley difference of the power grid requires the low load of the unit, the load of the unit is properly lifted, steam is pumped from a boiler 8 to a steam pipeline of a main steam turbine to a high-temperature steam-molten salt heat exchanger group 1 to heat cold molten salt pumped out by a cold molten salt tank 7, the heated hot molten salt is selectively stored in a high-temperature hot molten salt tank 5 or a low-temperature hot molten salt tank 6 according to the temperature of the hot molten salt, and the steam after heat release can selectively heat boiler feed water to a high-pressure heater module 18 or heat condensed water to a deaerator 16 or a low-pressure heater module 15 according to parameter characteristics, or heat inlet air to a primary air heater 27 and an air supply heater 28, or heat flue gas to a flue gas heater 36 or heat flue gas pipeline 20 or heat supply to a heat supply system 21;

a2. pumping steam from a boiler 8 to a steam pipeline of a main steam turbine or a steam pumping pipeline of the main steam turbine to a low-temperature steam-molten salt heat exchanger group 2, heating cold molten salt pumped out by a cold molten salt tank 7, and storing the heated low-temperature hot molten salt in a low-temperature hot molten salt tank 6, wherein the steam after heat release can selectively heat boiler feed water to a high-pressure heater module 18, or heat condensed water to a deaerator 16 or a low-pressure heater module 15, or heat boiler inlet air to a primary air heater 27 and an air supply heater 28, or heat flue gas to a flue gas heater 36, or heat auxiliary steam pipeline 20, or heat supply to a heat supply system 21 according to parameter characteristics;

b1. when the power grid requires high load or high heat supply load, high-temperature hot-melt salt is pumped out from a high-temperature hot-melt salt tank 5 to a high-temperature molten salt-steam heat exchanger group 3 to heat steam extracted from a steam extraction pipeline of a main steam turbine, and then molten salt is selectively stored in a low-temperature hot-melt salt tank 6 or a cold-melt salt tank 7 according to the temperature of the molten salt; the heated steam can selectively heat boiler feed water to the high-pressure heater module 18 according to parameter characteristics, or to the feed water pump small turbine 17, or to the induced draft fan small turbine 33, or to the heating system 21;

b2. low-temperature hot molten salt is pumped out from a low-temperature hot molten salt tank 6 to a low-temperature molten salt-steam heat exchanger group 4 to heat steam extracted from a steam extraction pipeline of a main steam turbine, then the molten salt is stored in a cold molten salt tank 7, and the heated steam can selectively heat boiler feed water to a high-pressure heater module 18 according to parameter characteristics, or heat boiler inlet air to a primary air heater 27 and an air supply heater 28, or heat flue gas to a flue gas heater 36, or heat supply to an auxiliary steam pipeline 20, or heat supply to a heat supply system 21.

When the thermal power generating unit is a reheating-free unit, the steam source of the high-temperature steam-molten salt heat exchanger group 1 is main steam, the steam source of the low-temperature steam-molten salt heat exchanger group 2 is steam extraction of a high-pressure cylinder 10 of a main steam turbine, steam heated by the high-temperature molten salt-steam heat exchanger group 3 is steam extraction of a low-pressure cylinder 12 of the main steam turbine, and steam heated by the low-temperature molten salt-steam heat exchanger group 4 is steam extraction of the low-pressure cylinder 12 of the main steam turbine;

when the thermal power generating unit is a single reheating unit, the steam source of the high-temperature steam-molten salt heat exchanger group 1 is main steam or high-temperature reheated steam, the steam source of the low-temperature steam-molten salt heat exchanger group 2 is low-temperature reheated steam or steam extracted by a main steam turbine high-pressure cylinder 10, steam heated by the high-temperature molten salt-steam heat exchanger group 3 is extracted from a main steam turbine intermediate pressure cylinder 11 or a main steam turbine low-pressure cylinder 12, and steam heated by the low-temperature molten salt-steam heat exchanger group 4 is extracted from the main steam turbine intermediate pressure cylinder 11 or the main steam turbine low-pressure cylinder 12;

when the thermal power generating unit is a secondary reheating unit, the steam source of the high-temperature steam-molten salt heat exchanger group 1 is main steam or primary high-temperature reheat steam or secondary high-temperature reheat steam, the steam source of the low-temperature steam-molten salt heat exchanger group 2 is primary low-temperature reheat steam or secondary low-temperature reheat steam or steam extraction of a main steam turbine high-pressure cylinder 10, steam heated by the high-temperature molten salt-steam heat exchanger group 3 is extracted from a main steam turbine intermediate pressure cylinder 11 or a main steam turbine low-pressure cylinder 12, and steam heated by the low-temperature molten salt-steam heat exchanger group 4 is extracted from the main steam turbine intermediate pressure cylinder 11 or the main steam turbine low-pressure cylinder 12.

Wherein, when the steam heated by the molten salt or released heat to the molten salt reaches the high-pressure heater module 18, the steam can be preferably connected to a certain level of high-pressure heater according to the parameters; the low pressure heater module 15 may preferably be connected to a certain stage of low pressure heater according to its parameters.

Certainly, the high-temperature steam-molten salt heat exchanger group 1 and the high-temperature molten salt-steam heat exchanger group 3 can work simultaneously to store and discharge energy modules for high temperature; the low-temperature steam-molten salt heat exchanger group 2 and the low-temperature molten salt-steam heat exchanger group 4 can work simultaneously and are low-temperature energy storage and release modules; the high-temperature energy storage and release module and the low-temperature energy storage and release module can work simultaneously to realize cascade energy storage and release of the system.

In addition, when the high-temperature hot molten salt is pumped from the high-temperature hot molten salt tank 5 to the high-temperature molten salt-steam heat exchanger group 3, a proper amount of molten salt in the low-temperature hot molten salt tank 6 or the cold molten salt tank 7 can be converged into the high-temperature hot molten salt for temperature adjustment; when the low-temperature molten salt is pumped from the low-temperature molten salt tank 6 to the low-temperature molten salt-steam heat exchanger group 4, a proper amount of molten salt in the cold molten salt tank 7 can be converged into the low-temperature molten salt for temperature adjustment. The system connection lines for this function are omitted from the drawing.

The working medium in the heat storage process comprises molten salt and steam, and the working medium is required to work at the lowest temperature at which the molten salt is not solidified, and the lowest temperature is obtained by adding a certain allowance to the solidifying point of the working molten salt.

The highest temperature of the hot end of steam in the heat storage and release process can reach about 600 ℃, the highest temperature of the hot end of molten salt can reach about 565 ℃, the high-temperature hot-melt salt tank 5 is made of stainless steel, the low-temperature hot-melt salt tank 6 is made of stainless steel or carbon steel, and the cold-melt salt tank 7 is made of carbon steel.

The total heat storage capacity of the energy storage system depends on factors such as peak regulation demand characteristics of a power grid, heat supply load demand characteristics, unit capacity, unit parameter levels, available site space and the like, can be 0-100% of the unit heat capacity according to actual demands, and further can be optimally determined according to economy.

It should be understood that, in the present invention, under the principle of following the energy cascade utilization, the steam source and the destination of the fused salt cascade energy storage and release system are not limited to the above listed sources and users of the present invention, and can be selected or combined according to the actual situation of the thermal power generating unit, thereby constituting a new or preferred coupling system solution.

It should be understood that in the utility model, the molten salt step energy storage and discharge system can be an independent system, and can be used in other fields except the field of thermal power steam generating units, such as nuclear power generating units and heat conducting oil furnaces (high-temperature oil replaces steam and exchanges heat with molten salt); the heat storage medium can also be other media than molten salt, such as water, concrete, etc., therefore, the application of the stepped energy storage and release system with different application objects and different heat storage media will fall within the scope of the claims of the present invention, as long as the application is within the spirit of the present invention.

The above is the preferred embodiment of the present invention, and the technical personnel in the field of the present invention can also change and modify the above embodiment, therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by the technical personnel in the field on the basis of the present invention all belong to the protection scope of the present invention.

Claims

1. The utility model provides a fused salt step stores can peak shaving system of thermal power generating unit, its characterized in that includes:

the system comprises a thermal power generating unit, wherein the thermal power generating unit comprises a boiler (8), a main steam turbine, a condenser (13), a condensate pump (14), a water feeding pump (19), a heat return system, a small water turbine (17) of the water feeding pump, an auxiliary steam pipeline (20), a small induced draft fan steam turbine (33) and a smoke air system, the boiler (8) is connected with the main steam turbine through a steam pipeline, main steam is output to the main steam turbine, and low-temperature reheat steam from the main steam turbine is heated to high-temperature reheat steam and then is returned to the main steam turbine; the main steam turbine is connected with the heat recovery system, and part of steam is pumped to the heat recovery system for cyclic utilization; the boiler (8) is connected with a heat recovery system through a water supply pipeline, and the boiler (8) is connected with a smoke and air system through a primary air duct, an air supply duct and a flue;

the molten salt stepped energy storage and release system comprises a high-temperature steam-molten salt heat exchanger group (1), a low-temperature steam-molten salt heat exchanger group (2), a high-temperature molten salt-steam heat exchanger group (3), a low-temperature molten salt-steam heat exchanger group (4), a high-temperature hot-melt salt tank (5), a low-temperature hot-melt salt tank (6) and a cold-melt salt tank (7);

the molten salt side of the high-temperature steam-molten salt heat exchanger group (1) is connected with a high-temperature hot-melt salt tank (5), a low-temperature hot-melt salt tank (6) and a cold-melt salt tank (7); the steam side of the high-temperature steam-molten salt heat exchanger group (1) is connected with a steam pipeline from a boiler (8) to a main steam turbine, a regenerative system, an auxiliary steam pipeline (20), a heat supply system (21) and a smoke and air system, heat of steam from the boiler (8) to the steam pipeline of the main steam turbine is released to cold molten salt pumped out from a cold molten salt tank (7) to be changed into hot molten salt, the hot molten salt is stored in a high-temperature hot molten salt tank (5) and a low-temperature hot molten salt tank (6) according to the temperature gradient of the hot molten salt, and the released steam is used for the regenerative system, the auxiliary steam pipeline (20), the heat supply system (21) and the smoke and air system according to the parameter characteristic gradient of the;

the molten salt side of the low-temperature steam-molten salt heat exchanger group (2) is connected with a low-temperature molten salt tank (6) and a cold molten salt tank (7); the steam side of the low-temperature steam-molten salt heat exchanger group (2) is connected with a steam pipeline from a main steam turbine to a boiler (8), a steam extraction pipeline of the main steam turbine, a heat return system, an auxiliary steam pipeline (20), a heat supply system (21) and a smoke and air system, the heat of the steam from the main steam turbine to the steam pipeline of the boiler (8) or the steam extraction pipeline of the main steam turbine is released to cold molten salt pumped out from a cold molten salt tank (7) to be low-temperature hot molten salt and stored in a low-temperature hot molten salt tank (6), and the released steam is used for the heat return system, the auxiliary steam pipeline (20), the heat supply system (21) and the smoke and air system according to the parameter characteristic steps;

the molten salt side of the high-temperature molten salt-steam heat exchanger group (3) is connected with a high-temperature hot-melt salt tank (5), a low-temperature hot-melt salt tank (6) and a cold-melt salt tank (7); the high-temperature molten salt-steam heat exchanger group (3) is connected with a steam extraction pipeline of a main steam turbine, a heat recovery system, a heat supply system (21), a small steam turbine (17) of a water supply pump and a small steam turbine (33) of an induced draft fan on the steam side, heat stored by high-temperature and high-temperature molten salt in the high-temperature molten salt tank (5) is released to steam from the steam extraction pipeline of the main steam turbine, parameters of the steam are improved, the heat is used for the heat recovery system, the heat supply system (21), the small steam turbine (17) of the water supply pump and the small steam turbine (33) of the induced draft fan according to parameter characteristic steps, and the released molten salt is stored in the low-temperature molten salt tank;

the molten salt side of the low-temperature molten salt-steam heat exchanger group (4) is connected with a low-temperature hot molten salt tank (6) and a cold molten salt tank (7); the low-temperature molten salt-steam heat exchanger group (4) is connected with a steam extraction pipeline of a main steam turbine, a heat regeneration system, a heat supply system (21), an auxiliary steam pipeline (20) and a smoke and air system on the steam side, releases heat stored by low-temperature and low-temperature molten salt in the low-temperature molten salt tank (6) to steam from the steam extraction pipeline of the main steam turbine, improves parameters of the steam, is used for the heat regeneration system, the heat supply system (21), the auxiliary steam pipeline (20) and the smoke and air system according to the parameter characteristics of the steam, and stores the released molten salt in the cold molten salt tank (7).

2. The fused salt stepped energy storage and peak regulation system of the thermal power generating unit as claimed in claim 1, wherein: the high-temperature steam-molten salt heat exchanger group (1) can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the low-temperature steam-molten salt heat exchanger group (2) can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the high-temperature molten salt-steam heat exchanger group (3) can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel; the low-temperature molten salt-steam heat exchanger group (4) can be a heat exchanger, and can also be formed by connecting a plurality of heat exchangers in series or in parallel.

3. The fused salt stepped energy storage and peak regulation system of the thermal power generating unit as claimed in claim 1, wherein: the heat recovery system comprises a low-pressure heater module (15), a deaerator (16) and a high-pressure heater module (18) which are sequentially connected, and a condenser (13) and a condensate pump (14) are sequentially connected between the main turbine and the low-pressure heater module (15); a water feeding pump (19) is connected between the deaerator (16) and the high-pressure heater module (18), the water feeding pump (19) is driven by a small water feeding pump turbine (17), and the small water feeding pump turbine (17) is connected with the steam side of the high-temperature molten salt-steam heat exchanger group (3); the high-pressure heater module (18) is connected with an economizer (22) of the boiler (8) through a water supply pipeline, and the low-pressure heater module (15) and the deaerator (16) are respectively connected with the steam sides of the high-temperature steam-molten salt heat exchanger group (1) and the low-temperature steam-molten salt heat exchanger group (2); the high-pressure heater module (18) is respectively connected with the steam sides of the high-temperature steam-molten salt heat exchanger group (1), the low-temperature steam-molten salt heat exchanger group (2), the high-temperature molten salt-steam heat exchanger group (3) and the low-temperature molten salt-steam heat exchanger group (4).

4. The fused salt stepped energy storage and peak regulation system of the thermal power generating unit as claimed in claim 1, wherein: the smoke and air system comprises a smoke system and an air system, the smoke system is sequentially connected with a dust remover (32), an induced draft fan (34), a desulfurizing tower (35), a smoke heater (36) and a chimney (37) through a flue from the rear of an air preheater (31) of a boiler (8), the induced draft fan (34) is driven by a small induced draft fan turbine (33), and the small induced draft fan turbine (33) is connected with the steam side of the high-temperature molten salt-steam heat exchanger group (3); the air system comprises a primary air heater (27), an air supply heater (28), a primary air fan (29) and an air feeder (30), wherein the primary air fan (29) and the air feeder (30) are respectively connected with the primary air heater (27) and the air supply heater (28) through a primary air duct and an air supply duct and then are connected with the boiler (8) through the primary air duct and the air supply duct, and the primary air heater (27), the air supply heater (28) and the flue gas heater (36) are equally divided into a high-temperature steam-molten salt heat exchanger group (1), a low-temperature steam-molten salt heat exchanger group (2) and a low-temperature molten salt-steam heat exchanger group (4) and are connected with the steam side.

5. The fused salt stepped energy storage and peak regulation system of the thermal power generating unit as claimed in claim 1, wherein: the thermal power generating unit comprises a non-reheating unit, a primary reheating unit and a secondary reheating unit.

6. The fused salt stepped energy storage and peak regulation system of the thermal power generating unit as claimed in claim 5, characterized in that: when the thermal power generating unit is a reheating-free unit, the main steam turbine comprises a main steam turbine high-pressure cylinder (10) and a main steam turbine low-pressure cylinder (12), and the main steam turbine high-pressure cylinder (10) is connected with a superheater (24) of a boiler (8) through a main steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group (1) is connected with a main steam pipeline, and heat of steam from the main steam pipeline is released to cold molten salt pumped out from a cold molten salt tank (7); the steam side of the low-temperature steam-molten salt heat exchanger group (2) is connected with a steam extraction pipeline of a main steam turbine high-pressure cylinder (10), and heat of steam in the steam extraction pipeline of the main steam turbine high-pressure cylinder (10) is released to cold molten salt pumped out from a cold molten salt tank (7); the steam side of the high-temperature molten salt-steam heat exchanger group (3) is connected with a steam extraction pipeline of the main steam turbine low-pressure cylinder (12), and heat stored by high-temperature molten salt in the high-temperature molten salt tank (5) is released to steam from the steam extraction pipeline of the main steam turbine low-pressure cylinder (12); the steam side of the low-temperature molten salt-steam heat exchanger group (4) is connected with a steam extraction pipeline of a main steam turbine low-pressure cylinder (12), and heat stored by low-temperature hot molten salt in the low-temperature hot molten salt tank (6) is released to steam from the steam extraction pipeline of the main steam turbine low-pressure cylinder (12); and the main turbine low-pressure cylinder (12) is connected with a condenser (13).

7. The fused salt stepped energy storage and peak regulation system of the thermal power generating unit as claimed in claim 5, characterized in that: when the thermal power generating unit is a primary reheating unit, the main steam turbine comprises a main steam turbine high-pressure cylinder (10), a main steam turbine intermediate-pressure cylinder (11) and a main steam turbine low-pressure cylinder (12), and the main steam turbine high-pressure cylinder (10) is connected with a superheater (24) and a primary reheater (25) of a boiler (8) through a main steam pipeline and a low-temperature reheating steam pipeline respectively; the primary reheater (25) is then connected with a main turbine intermediate pressure cylinder (11) through a high-temperature reheating steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group (1) is connected with a main steam pipeline and a high-temperature reheating steam pipeline, and heat of steam from the main steam pipeline or the high-temperature reheating steam pipeline is released to cold molten salt pumped out from a cold molten salt tank (7); the steam side of the low-temperature steam-molten salt heat exchanger group (2) is connected with a low-temperature reheating steam pipeline and a steam extraction pipeline of a main steam turbine high-pressure cylinder (10), and heat of steam from the low-temperature reheating steam pipeline or the steam extraction pipeline of the main steam turbine high-pressure cylinder (10) is released to cold molten salt pumped out from a cold molten salt tank (7); the steam side of the high-temperature molten salt-steam heat exchanger group (3) is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder (11) and a steam extraction pipeline of a main steam turbine low pressure cylinder (12), and heat stored by high-temperature and high-temperature molten salt in the high-temperature molten salt tank (5) is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder (11) or the steam extraction pipeline of the main steam turbine low pressure cylinder (12); the steam side of the low-temperature molten salt-steam heat exchanger group (4) is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder (11) and a steam extraction pipeline of a main steam turbine low pressure cylinder (12), and heat stored by low-temperature hot molten salt in the low-temperature hot molten salt tank (6) is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder (11) or the steam extraction pipeline of the main steam turbine low pressure cylinder (12); and the main turbine low-pressure cylinder (12) is connected with a condenser (13).

8. The fused salt stepped energy storage and peak regulation system of the thermal power generating unit as claimed in claim 5, characterized in that: when the thermal power generating unit is a secondary reheating unit, the main steam turbine comprises a main steam turbine ultrahigh pressure cylinder (9), a main steam turbine high pressure cylinder (10), a main steam turbine intermediate pressure cylinder (11) and a main steam turbine low pressure cylinder (12), wherein the main steam turbine ultrahigh pressure cylinder (9) is respectively connected with a superheater (24) and a primary reheater (25) of a boiler (8) through a main steam pipeline and a primary low-temperature reheated steam pipeline; the main turbine high-pressure cylinder (10) is respectively connected with a primary reheater (25) and a secondary reheater (26) of the boiler (8) through a primary high-temperature reheated steam pipeline and a secondary low-temperature reheated steam pipeline; the main turbine intermediate pressure cylinder (11) is connected with a secondary reheater (26) of the boiler (8) through a secondary high-temperature reheating steam pipeline; the steam side of the high-temperature steam-molten salt heat exchanger group (1) is connected with a main steam pipeline, a primary high-temperature reheating steam pipeline and a secondary high-temperature reheating steam pipeline, and the heat of the steam from the main steam pipeline, the primary high-temperature reheating steam pipeline or the secondary high-temperature reheating steam pipeline is released to cold molten salt pumped out from a cold molten salt tank (7); the steam side of the low-temperature steam-molten salt heat exchanger group (2) is connected with a primary low-temperature reheating steam pipeline, a secondary low-temperature reheating steam pipeline and a steam extraction pipeline of a main steam turbine high-pressure cylinder (10), and heat of steam from the primary low-temperature reheating steam pipeline or the secondary low-temperature reheating steam pipeline or the steam extraction pipeline of the main steam turbine high-pressure cylinder (10) is released to cold molten salt pumped out from a cold molten salt tank (7); the steam side of the high-temperature molten salt-steam heat exchanger group (3) is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder (11) and a steam extraction pipeline of a main steam turbine low pressure cylinder (12), and heat stored by high-temperature and high-temperature molten salt in the high-temperature molten salt tank (5) is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder (11) or the steam extraction pipeline of the main steam turbine low pressure cylinder (12); the steam side of the low-temperature molten salt-steam heat exchanger group (4) is connected with a steam extraction pipeline of a main steam turbine intermediate pressure cylinder (11) and a steam extraction pipeline of a main steam turbine low pressure cylinder (12), and heat stored by low-temperature hot molten salt in the low-temperature hot molten salt tank (6) is released to steam from the steam extraction pipeline of the main steam turbine intermediate pressure cylinder (11) or the steam extraction pipeline of the main steam turbine low pressure cylinder (12); and the main turbine low-pressure cylinder (12) is connected with a condenser (13).