Energy storage peak regulation system and method integrating molten salt heat storage and steam accumulator

Abstract

The present invention discloses an energy storage peak-shaving system and method integrating molten salt heat storage and steam accumulator, which relates to the field of energy storage peak-shaving of units. The system includes a steam power cycle power generation subsystem, a molten salt heat storage subsystem and a steam storage subsystem; when the unit is running at low load or reducing load, the energy of the main steam or other steam at the outlet of the steam generator is stored through molten salt and steam accumulator to realize low-load operation or rapid load reduction of the unit; when the unit is loaded, the heat of the high-temperature molten salt tank is released to heat the feed water, and the steam in the steam accumulator is released to replace the heat recovery steam or heat supply to increase the load change rate of the unit; the outlet high-pressure steam after the main steam molten salt heat storage is extracted can be better stored by the steam accumulator. The present invention improves the load change rate of the unit by integrating molten salt heat storage and steam accumulator energy storage, and can broaden the operating range of the unit, realize ultra-low load operation, and improve the power generation efficiency of the unit during rapid load change operation.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage peak regulation of units, and in particular to an energy storage peak regulation system and method integrating molten salt heat storage and steam accumulator. Background Art

[0002] The rapid development of renewable energy has put forward higher requirements for the flexibility of steam power cycle units. In order to provide more grid-connected space for renewable energy power, traditional steam power cycle generators should improve their flexible operation capabilities and deep peak-shaving capabilities. The deep peak-shaving and flexible operation capabilities of China's thermal power units are far behind the world's advanced levels. The actual peak-shaving capacity of pure condensing units is generally about 50% of the rated power. In order to cater to the development of new energy, most gas-steam combined cycle units adopt a day-to-night stop mode, resulting in a mismatch between nighttime heat supply and demand, which also shows that there is great potential for improving the flexibility of thermal power units. The steam extraction heating molten salt heat storage energy storage system can broaden the peak-shaving space of the unit, improve the ability to absorb renewable energy, and realize the transfer of energy in time and space. However, only through molten salt heat storage, due to the limitation of the molten salt crystallization temperature, it is impossible to make the steam heat exchange to a lower temperature, and the energy storage efficiency is limited. Therefore, it is necessary to change the existing molten salt heat storage operation mode to further improve the flexible peak-shaving capacity of steam power cycle units. Summary of the invention

[0003] In response to the problems raised in the above background technology, the present invention provides an energy storage peak-shaving system and method integrating molten salt heat storage and steam accumulator to improve the load variable rate and flexibility of the unit.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] On the one hand, the present invention provides an energy storage peak-shaving system integrating molten salt heat storage and steam energy storage, comprising: a steam power cycle power generation subsystem, a molten salt heat storage subsystem and a steam energy storage subsystem;

[0006] The steam power cycle power generation subsystem includes: a steam generator, a steam turbine, a generator, a condenser, a low-pressure heater, a deaerator and a high-pressure heater; the molten salt heat storage subsystem includes: a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat exchanger, a molten salt steam heat exchanger, a first valve, a second valve and a third valve; the steam energy storage subsystem includes: a steam accumulator, a fourth valve, a fifth valve and a sixth valve; the main steam extraction at the steam generator outlet is connected to the steam turbine and the molten salt steam heat exchanger respectively; the reheated steam at the steam generator outlet is connected to the steam turbine; the generator is coaxially connected to the steam turbine; the first stage extraction of the steam turbine is connected to the high-pressure heater and the steam generator respectively; the second stage extraction of the steam turbine is connected to the deaerator; the third stage extraction of the steam turbine is connected to the low-pressure heater; the exhaust steam of the steam turbine is connected to the condenser; the condenser is connected to the low-pressure heater; the low-pressure heater The deaerator is connected to the water side inlet of the deaerator; the water side outlet of the deaerator is connected to the high-pressure heater; the high-pressure heater is connected to the steam generator; the high-temperature molten salt tank outlet is connected to the molten salt heat exchanger; the molten salt outlet of the molten salt heat exchanger is connected to the inlet of the low-temperature molten salt tank; the outlet of the low-temperature molten salt tank is connected to the molten salt steam heat exchanger; the molten salt outlet of the molten salt steam heat exchanger is connected to the inlet of the high-temperature molten salt tank; a first valve is provided on the connecting pipeline between the steam generator and the molten salt steam heat exchanger; a second valve is provided on the connecting pipeline between the low-temperature molten salt tank and the molten salt steam heat exchanger; a third valve is provided on the connecting pipeline between the high-temperature molten salt tank and the molten salt heat exchanger; the steam outlet of the molten salt steam heat exchanger is connected to the steam inlet of the steam accumulator; a fourth valve is provided on the connecting pipeline between the molten salt steam heat exchanger and the steam accumulator; a fifth valve is provided on the steam outlet pipeline of the steam accumulator; and a sixth valve is provided on the feed water inlet pipeline of the steam accumulator.

[0007] Applicable to the energy storage peak-shaving system integrating molten salt heat storage and steam accumulator, the present invention also provides an energy storage peak-shaving method integrating molten salt heat storage and steam accumulator, comprising:

[0008] When the unit is running at low load or reducing load, the first valve and the second valve are opened, and the third valve is closed, so that the steam at the steam generator outlet is exchanged with the low-temperature molten salt in the molten salt steam heat exchanger, and part of the heat is stored in the high-temperature molten salt tank; the fourth valve is opened to inject the steam at the molten salt steam heat exchanger outlet into the steam accumulator for steam storage;

[0009] When the unit increases its load or needs heating, open the third valve and close the second valve to release the heat stored in the high-temperature molten salt tank and heat the working fluid through the molten salt heat exchanger; open the fifth valve and close the fourth valve to release the steam in the steam accumulator as a steam source to replace the heat recovery steam or for heating; open the sixth valve and the feed water pump will inject part of the feed water into the steam accumulator to ensure a stable liquid level.

[0010] On the other hand, the present invention also provides an energy storage peak-shaving system integrating molten salt heat storage and steam energy storage, comprising: a steam power cycle power generation subsystem, a molten salt heat storage subsystem and a steam energy storage subsystem;

[0011] The steam power cycle power generation subsystem includes: a steam generator, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a condensate pump, a five-stage low-pressure heater group, a deaerator, a high-pressure water pump and a three-stage high-pressure heater group; the five-stage low-pressure heater group includes a first-stage low-pressure heater, a second-stage low-pressure heater, a third-stage low-pressure heater, a fourth-stage low-pressure heater and a fifth-stage low-pressure heater connected in sequence; the three-stage high-pressure heater group includes a first-stage high-pressure heater, a second-stage high-pressure heater and a third-stage high-pressure heater connected in sequence;

[0012] The molten salt heat storage subsystem includes: a high-temperature molten salt tank, a low-temperature molten salt tank, a fourth valve, a high-temperature molten salt pump, a molten salt feed water heat exchanger, a third valve, a low-temperature molten salt pump, a molten salt steam heat exchanger, a first valve and a second valve;

[0013] The steam energy storage subsystem comprises: a steam accumulator, a fifth valve, a seventh valve, a feed water pump and a sixth valve;

[0014] The main steam extraction at the steam generator outlet is connected to the high-pressure cylinder and the molten salt steam heat exchanger respectively; the reheated steam at the steam generator outlet is connected to the medium-pressure cylinder and the low-pressure cylinder respectively; the generator is coaxially connected to the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder; the high-pressure cylinder extraction is connected to the first-stage high-pressure heater; the high-pressure cylinder exhaust is connected to the steam generator and the second-stage high-pressure heater respectively; the medium-pressure cylinder extraction is connected to the third-stage high-pressure heater, the deaerator and the first-stage low-pressure heater respectively; the low-pressure cylinder extraction is connected to the second-stage low-pressure heater, the third-stage low-pressure heater, the fourth-stage low-pressure heater and the fifth-stage low-pressure heater respectively; the low-pressure cylinder exhaust is connected to the condenser; the condenser is connected to the condensate pump; the condensate pump is connected to the five-stage low-pressure heater group; the first-stage low-pressure heater is connected to the water side inlet of the deaerator; the water side outlet of the deaerator is connected to the high-pressure water pump; the high-pressure water pump is connected to the three-stage high-pressure heater group; the first-stage high-pressure heater is connected to the steam generator;

[0015] The outlet of the high-temperature molten salt tank is connected to the molten salt water feed heat exchanger through a high-temperature molten salt pump; the molten salt outlet of the molten salt water feed heat exchanger is connected to the inlet of the low-temperature molten salt tank; the outlet of the low-temperature molten salt tank is connected to the molten salt steam heat exchanger through a low-temperature molten salt pump; the molten salt outlet of the molten salt steam heat exchanger is connected to the inlet of the high-temperature molten salt tank; the water side inlet of the molten salt water feed heat exchanger is connected to a high-pressure water pump; the water side outlet of the molten salt water feed heat exchanger is connected to a steam generator; a first valve is provided on the connecting pipeline between the steam generator and the molten salt steam heat exchanger; a second valve is provided on the connecting pipeline between the high-pressure water pump and the molten salt water feed heat exchanger; a third valve is provided on the connecting pipeline between the low-temperature molten salt tank and the molten salt steam heat exchanger; a fourth valve is provided on the connecting pipeline between the high-temperature molten salt tank and the molten salt water feed heat exchanger;

[0016] The steam outlet of the molten salt steam heat exchanger is connected to the steam inlet of the steam accumulator; the feed water pump is connected to the feed water inlet of the steam accumulator; the steam outlet of the steam accumulator is respectively connected to the third-stage high-pressure heater and the deaerator; a fifth valve is provided on the connecting pipeline between the molten salt steam heat exchanger and the steam accumulator; a sixth valve is provided on the connecting pipeline between the steam accumulator and the third-stage high-pressure heater and the deaerator; and a seventh valve is provided on the connecting pipeline between the feed water pump and the steam accumulator.

[0017] Applicable to the energy storage peak-shaving system integrating molten salt heat storage and steam accumulator, the present invention also provides an energy storage peak-shaving method integrating molten salt heat storage and steam accumulator, comprising:

[0018] When the unit is running at low load or reducing load, open the first valve and the third valve, close the fourth valve, and exchange heat between the main steam at the steam generator outlet and the low-temperature molten salt in the molten salt steam heat exchanger, and store part of the heat in the high-temperature molten salt tank; open the fifth valve to inject the steam at the outlet of the molten salt steam heat exchanger into the steam accumulator for steam storage;

[0019] When the unit increases its load, open the fourth valve and the second valve, close the third valve, release the heat stored in the high-temperature molten salt tank, and heat the feed water through the molten salt feed water heat exchanger; open the sixth valve, close the fifth valve, release the steam in the steam accumulator as heating steam for the third-stage high-pressure heater and deaerator; open the seventh valve, and the feed water pump will inject part of the feed water into the steam accumulator.

[0020] Optionally, the energy storage peak regulation method integrating molten salt heat storage and steam accumulator further includes:

[0021] By adjusting the opening of the first valve, the flow rate of the extracted main steam and the load reduction rate are controlled;

[0022] By adjusting the opening of the seventh valve, the amount of water in the steam accumulator is controlled, thereby adjusting the steam pressure and temperature at the steam accumulator outlet;

[0023] The opening of the second valve is controlled to control the feed water flow rate of the molten salt feed water heat exchanger, thereby controlling the high-temperature feed water outlet temperature of the molten salt feed water heat exchanger.

[0024] Optionally, the steam power cycle power generation subsystem includes a coal-fired power generation subsystem, a biomass power generation subsystem, a waste combustion power generation subsystem, a nuclear power generation subsystem and a geothermal power generation subsystem.

[0025] Optionally, the operating temperature of the high-temperature molten salt tank is 565°C.

[0026] Optionally, the operating temperature of the low-temperature molten salt tank is 290°C.

[0027] Optionally, the molten salt is a binary salt.

[0028] Optionally, the steam accumulator operates at sliding pressure, and the operating pressure range is 1.0-2.7 MPa.

[0029] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0030] The energy storage peak-shaving system and method of the integrated molten salt heat storage and steam accumulator provided by the present invention, the energy storage peak-shaving system includes a steam power cycle power generation subsystem, a molten salt heat storage subsystem and a steam storage subsystem; when the unit is running at low load or reducing load, the present invention stores part of the steam energy at the outlet of the steam generator through molten salt and steam accumulator to achieve low-load operation and flexibility of the unit; when the unit is loaded, the heat of the high-temperature molten salt tank is released to heat the feed water, and the released steam in the steam accumulator is released to replace the reheated steam or heat supply to improve the load change rate and flexibility of the unit; the outlet high-pressure steam after the molten salt heat storage can be better stored by the steam accumulator. The present invention improves the load change rate and flexibility of the unit by integrating molten salt heat storage and steam accumulator energy storage peak-shaving, and can broaden the operating range of the steam power cycle power generation unit to achieve ultra-low load operation; improves the power generation efficiency of the steam power cycle power generation unit when the load changes rapidly; realizes the transfer of energy in time and space, and solves the problems caused by the mismatch between the supply and demand of thermal energy in time, space or intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1This is a structural schematic diagram of Embodiment 1 of an energy storage and peak-shaving system integrating molten salt heat storage and steam accumulators of the present invention.

[0033] Figure 2 This is a structural schematic diagram of Embodiment 2 of an energy storage and peak-shaving system integrating molten salt heat storage and steam accumulators according to the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The purpose of the present invention is to provide an energy storage peak-shaving system and method integrating molten salt heat storage and steam accumulator. By integrating molten salt heat storage and steam accumulator on the basis of steam power cycle generator set, lower load operation and higher load variable rate and flexibility can be achieved; at the same time, molten salt tanks and steam accumulators are integrated to store energy, and energy is released when needed to achieve energy transfer in time and space. Reduce energy consumption and solve the problem caused by the mismatch between heat supply and demand. This system is applicable to all steam units for energy storage peak-shaving.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] The present invention provides an energy storage peak-shaving system integrating molten salt heat storage and steam accumulator, comprising: a steam power cycle power generation subsystem, a molten salt heat storage subsystem and a steam energy storage subsystem. In practical applications, the steam power cycle power generation subsystem can be any device that uses water vapor or steam of other substances as a working fluid, utilizes chemical energy, nuclear energy, geothermal energy or solar energy, etc., and converts thermal energy into mechanical energy in a certain thermal cycle. Two specific embodiments of the energy storage peak-shaving system integrating molten salt heat storage and steam accumulator of the present invention are provided below.

[0038] Embodiment 1

[0039] like Figure 1As shown, in the first embodiment, the steam power cycle power generation subsystem includes: a steam generator 1, a steam turbine 2, a generator 3, a condenser 4, a low-pressure heater 5, a deaerator 6 and a high-pressure heater 7; the molten salt heat storage subsystem includes: a high-temperature molten salt tank 8, a low-temperature molten salt tank 9, a molten salt heat exchanger 10, a molten salt steam heat exchanger 11, a first valve 12, a second valve 13 and a third valve 14; the steam energy storage subsystem includes: a steam accumulator 15, a fourth valve 16, a fifth valve 17 and the sixth valve 18; the main steam extraction at the outlet of the steam generator 1 is connected to the steam turbine 2 and the molten salt steam heat exchanger 11 respectively; the reheated steam at the outlet of the steam generator 1 is connected to the steam turbine 2; the generator 3 is coaxially connected to the steam turbine 2; the first stage extraction of the steam turbine 2 is connected to the high pressure heater 7 and the steam generator 1 respectively; the second stage extraction of the steam turbine 2 is connected to the deaerator 6; the third stage extraction of the steam turbine 2 is connected to the low pressure heater 5; the exhaust steam of the steam turbine 2 is connected to the condenser 4; the condenser 4 is connected to the low pressure heater 5; the low The high-pressure heater 5 is connected to the water side inlet of the deaerator 6; the water side outlet of the deaerator 6 is connected to the high-pressure heater 7; the high-pressure heater 7 is connected to the steam generator 1; the outlet of the high-temperature molten salt tank 8 is connected to the molten salt heat exchanger 10; the molten salt outlet of the molten salt heat exchanger 10 is connected to the inlet of the low-temperature molten salt tank 9; the outlet of the low-temperature molten salt tank 9 is connected to the molten salt steam heat exchanger 11; the molten salt outlet of the molten salt steam heat exchanger 11 is connected to the inlet of the high-temperature molten salt tank 8; a first valve 12 is provided on the connecting pipeline between the steam generator 1 and the molten salt steam heat exchanger 11; A second valve 13 is provided on the connecting pipeline between the salt tank 9 and the molten salt steam heat exchanger 11; a third valve 14 is provided on the connecting pipeline between the high-temperature molten salt tank 8 and the molten salt heat exchanger 10; the steam outlet of the molten salt steam heat exchanger 11 is connected to the steam inlet of the steam accumulator 15; a fourth valve 16 is provided on the connecting pipeline between the molten salt steam heat exchanger 11 and the steam accumulator 15; a fifth valve 17 is provided on the steam outlet pipeline of the steam accumulator 15; and a sixth valve 18 is provided on the water feed inlet pipeline of the steam accumulator 15.

[0040] In the energy storage peak-shaving system integrating molten salt heat storage and steam accumulator, the steam outlet of steam generator 1 is connected to steam turbine 2 through a pipeline, and the steam outlet of steam turbine 2 is connected to condenser 4 through a pipeline. When the system is working, the main steam generated by steam generator 1 enters steam turbine 2 through a pipeline to perform work, and part of the outlet steam after the steam turbine 2 performs work enters steam generator 1 for reheating, and the reheated steam enters steam turbine 2 to perform work and generates electricity through generator 3. The steam at the outlet of steam turbine 2 enters condenser 4 for condensation, and the condensed water at the outlet of condenser 4 enters low-pressure heater 5 for heating by extraction steam. If there is no heat recovery system, the condensed water directly enters steam generator 1 after passing through deaerator 6. The outlet feed water of low-pressure heater 5 is heated and deoxygenated by deaerator 6, and the outlet feed water of water side of deaerator 6 enters high-pressure heater 7 for heating by extraction steam, and the outlet feed water of high-pressure heater 7 enters steam generator 1.

[0041] Based on the system, the present invention also proposes an energy storage peak regulation method integrating molten salt heat storage and steam accumulator, comprising:

[0042] When the unit is running at low load or reducing load, the first valve 12 and the second valve 13 are opened, and the third valve 14 is closed, and the steam at the outlet of the steam generator 1 is heat exchanged with the low-temperature molten salt in the molten salt steam heat exchanger 11, and part of the heat is stored in the high-temperature molten salt tank 8; the fourth valve 16 is opened to inject the steam at the outlet of the molten salt steam heat exchanger 11 into the steam accumulator 15 for steam storage; the extracted steam includes but is not limited to main steam, reheat steam and other higher parameter steam.

[0043] When the unit increases its load or needs to supply heat, the third valve 14 is opened and the second valve 13 is closed to release the heat stored in the high-temperature molten salt tank 8 and heat the working medium through the molten salt heat exchanger 10; the fifth valve 17 is opened and the fourth valve 16 is closed to release the steam in the steam accumulator 15 as a steam source to replace the heat recovery steam or for heating; the sixth valve 18 is opened and the feed water pump injects part of the feed water into the steam accumulator 15 to ensure a stable liquid level.

[0044] By adjusting the opening of the first valve 12, the flow rate of the extracted main steam and the load reduction rate are controlled.

[0045] By adjusting the opening of the sixth valve 18 , the amount of water in the steam accumulator 15 is controlled, thereby adjusting the steam pressure and temperature at the outlet of the steam accumulator 15 .

[0046] The present invention couples an energy storage and peak-shaving system composed of a molten salt tank, a steam accumulator and a valve on the basis of a steam power cycle unit. The system can improve the variable load rate and flexibility of the unit. Combining molten salt heat storage with a steam accumulator can broaden the peak-shaving space of the unit. When operating at low load or reducing load, the system stores part of the steam heat at the outlet of the steam generator through molten salt, and stores the high-pressure steam after heat exchange in the steam accumulator, so as to achieve lower load operation and faster load reduction rate and flexibility of the unit; when increasing the load, the system releases the heat stored in the high-temperature molten salt tank to heat the working fluid, and at the same time releases the steam stored in the steam accumulator to replace heat recovery extraction or heating, thereby improving the load increase rate and flexibility. The system and method of the present invention can be applied to energy storage and peak-shaving of all steam units, and has broad application prospects.

[0047] Embodiment 2

[0048] like Figure 2As shown, in the second embodiment, the energy storage peak-shaving system of the present invention integrating molten salt heat storage and steam accumulator includes: a steam power cycle power generation subsystem, a molten salt heat storage subsystem and a steam energy storage subsystem. The steam power cycle power generation subsystem includes: a steam generator 101, a high-pressure cylinder 102, a medium-pressure cylinder 103, a low-pressure cylinder 104, a generator 105, a condenser 106, a condensate pump 107, a five-stage low-pressure heater group, a deaerator 113, a high-pressure water pump 114 and a three-stage high-pressure heater group; the five-stage low-pressure heater group includes a first-stage low-pressure heater 112, a second-stage low-pressure heater 111, a third-stage low-pressure heater 110, a fourth-stage low-pressure heater 109 and a fifth-stage low-pressure heater 108 connected in sequence; the three-stage high-pressure heater group includes a first-stage high-pressure heater 117, a second-stage high-pressure heater 116 and a third-stage high-pressure heater 115 connected in sequence. The molten salt heat storage subsystem includes: a high-temperature molten salt tank 201, a low-temperature molten salt tank 202, a fourth valve 203, a high-temperature molten salt pump 204, a molten salt feed water heat exchanger 205, a third valve 206, a low-temperature molten salt pump 207, a molten salt steam heat exchanger 208, a first valve 209 and a second valve 210. The steam energy storage subsystem includes: a steam accumulator 301, a fifth valve 302, a seventh valve 303, a feed water pump 304 and a sixth valve 305.

[0049] The main steam extraction at the outlet of the steam generator 101 is connected to the high-pressure cylinder 102 and the molten salt steam heat exchanger 208 respectively; the reheated steam at the outlet of the steam generator 101 is connected to the medium-pressure cylinder 103 and the low-pressure cylinder 104 respectively; the generator 105 is coaxially connected to the high-pressure cylinder 102, the medium-pressure cylinder 103 and the low-pressure cylinder 104; the extraction steam of the high-pressure cylinder 102 is connected to the first-stage high-pressure heater 117; the exhaust steam of the high-pressure cylinder 102 is connected to the steam generator 101 and the second-stage high-pressure heater 116 respectively; the extraction steam of the medium-pressure cylinder 103 is connected to the third-stage high-pressure heater 115, the deaerator 113 and the first-stage low-pressure heater 11 2; the extraction steam of the low-pressure cylinder 104 is respectively connected to the second-stage low-pressure heater 111, the third-stage low-pressure heater 110, the fourth-stage low-pressure heater 109 and the fifth-stage low-pressure heater 108; the exhaust steam of the low-pressure cylinder 104 is connected to the condenser 106; the condenser 106 is connected to the condensate pump 107; the condensate pump 107 is connected to the five-stage low-pressure heater group; the first-stage low-pressure heater 112 is connected to the water side inlet of the deaerator 113; the water side outlet of the deaerator 113 is connected to the high-pressure water pump 114; the high-pressure water pump 114 is connected to the three-stage high-pressure heater group; the first-stage high-pressure heater 117 is connected to the steam generator 101.

[0050] The outlet of the high-temperature molten salt tank 201 is connected to the molten salt water feed heat exchanger 205 through the high-temperature molten salt pump 204; the molten salt outlet of the molten salt water feed heat exchanger 205 is connected to the inlet of the low-temperature molten salt tank 202; the outlet of the low-temperature molten salt tank 202 is connected to the molten salt steam heat exchanger 208 through the low-temperature molten salt pump 207; the molten salt outlet of the molten salt steam heat exchanger 208 is connected to the inlet of the high-temperature molten salt tank 201; the water side inlet of the molten salt water feed heat exchanger 205 is connected to the high-pressure water pump 114; the water side of the molten salt water feed heat exchanger 205 The outlet is connected to the steam generator 101; a first valve 209 is provided on the connecting pipeline between the steam generator 101 and the molten salt steam heat exchanger 208; a second valve 210 is provided on the connecting pipeline between the high-pressure water pump 114 and the molten salt feed water heat exchanger 205; a third valve 206 is provided on the connecting pipeline between the low-temperature molten salt tank 202 and the molten salt steam heat exchanger 208; a fourth valve 203 is provided on the connecting pipeline between the high-temperature molten salt tank 201 and the molten salt feed water heat exchanger 205.

[0051] The steam outlet of the molten salt steam heat exchanger 208 is connected to the steam inlet of the steam accumulator 301; the feed water pump 304 is connected to the feed water inlet of the steam accumulator 301; the steam outlet of the steam accumulator 301 is respectively connected to the third-stage high-pressure heater 115 and the deaerator 113; a fifth valve 302 is provided on the connecting pipeline between the molten salt steam heat exchanger 208 and the steam accumulator 301; a sixth valve 305 is provided on the connecting pipeline between the steam accumulator 301 and the third-stage high-pressure heater 115 and the deaerator 113; a seventh valve 303 is provided on the connecting pipeline between the feed water pump 304 and the steam accumulator 301.

[0052] Preferably, the working temperature of the high-temperature molten salt tank 201 is 565° C. The working temperature of the low-temperature molten salt tank 202 is 290° C. The type of the molten salt is binary salt.

[0053] Preferably, the steam accumulator 301 operates at sliding pressure, and the operating pressure range is 1.0-2.7 MPa.

[0054] In the energy storage peak-shaving system integrating molten salt heat storage and steam accumulator, the steam outlet of the steam generator 101 is connected to the high-pressure cylinder 102 through a pipeline, and the outlet steam of the high-pressure cylinder 102 enters the steam generator 101 for reheating, and then enters the medium-pressure cylinder 103 and the low-pressure cylinder 104 in sequence, and the steam outlet of the low-pressure cylinder 104 is connected to the condenser 106 through a pipeline. When the system is working, the main steam generated by the steam generator 101 enters the high-pressure cylinder 102 through a pipeline to do work, and the outlet steam after the high-pressure cylinder 102 does work enters the steam generator 101 for reheating, and the reheated steam enters the medium-pressure cylinder 103 and the low-pressure cylinder 104 in sequence to do work and generates electricity through the generator 105. The steam at the outlet of the low-pressure cylinder 104 enters the condenser 106 for condensation, and the condensed water at the outlet of the condenser 106 enters the low-pressure heater group 108-112 in sequence through the condensate pump 107 for heating by extraction steam. The feed water at the outlet of the first-stage low-pressure heater 112 is heated and deoxygenated by the deaerator 113, and the feed water at the water side outlet of the deaerator 113 enters the high-pressure heater group 115-117 in sequence through the high-pressure water pump 114 for heating by extraction steam. The feed water at the outlet of the high-pressure heater 117 enters the steam generator 101. The present invention pumps feed water through the feed water pump 304 to control the amount of water in the steam accumulator 301, thereby adjusting the steam pressure and temperature at the outlet of the steam accumulator 301.

[0055] Based on the system, the present invention also proposes an energy storage peak regulation method integrating molten salt heat storage and steam accumulator, comprising:

[0056] When the unit is running at low load or reducing load, the first valve 209 and the third valve 206 are opened, and the fourth valve 203 is closed. The main steam at the outlet of the steam generator 101 is exchanged with the low-temperature molten salt in the molten salt steam heat exchanger 208, and part of the heat is stored in the high-temperature molten salt tank 201; the fifth valve 302 is opened to inject the steam at the outlet of the molten salt steam heat exchanger 208 into the steam accumulator 301 for steam storage.

[0057] When the unit increases its load, the fourth valve 203 and the second valve 210 are opened, and the third valve 206 is closed to release the heat stored in the high-temperature molten salt tank 201, and heat the feed water through the molten salt feed water heat exchanger 205; the sixth valve 305 is opened, and the fifth valve 302 is closed to release the steam in the steam accumulator 301 as heating steam for the third-stage high-pressure heater 115 and the deaerator 113; the seventh valve 303 is opened, and the feed water pump 304 injects part of the feed water into the steam accumulator 301.

[0058] By adjusting the opening of the first valve 209, the flow rate of the extracted main steam and the load reduction rate are controlled. By adjusting the opening of the seventh valve 303, the water volume in the steam accumulator 301 is controlled, and the steam pressure and temperature at the outlet of the steam accumulator 301 are adjusted. By controlling the opening of the second valve 210, the feed water flow rate of the molten salt feed water heat exchanger 205 is controlled, and the high-temperature feed water outlet temperature of the molten salt feed water heat exchanger 205 is controlled.

[0059] The present invention couples an energy storage and peak-shaving system composed of a molten salt tank, a steam accumulator and a valve on the basis of a steam power cycle unit. The system can improve the variable load rate and flexibility of the unit. The combination of molten salt heat storage and steam accumulator can broaden the peak-shaving space of the unit and ensure the safe operation of the steam generator. When operating at low load or reducing load, the system stores part of the steam heat at the outlet of the steam generator through molten salt, and stores the high-pressure steam after heat exchange in the steam accumulator, so as to achieve lower load operation and faster load reduction rate and flexibility of the unit; when increasing the load, the system releases the heat stored in the high-temperature molten salt tank to heat the working fluid, and at the same time releases the steam stored in the steam accumulator, which can reduce the heat recovery extraction or heating of the turbine and improve the load increase rate and flexibility. The system and method of the present invention can be applied to energy storage and peak-shaving of all steam units, and has broad application prospects.

[0060] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An energy storage peak regulation system integrating molten salt heat storage and steam accumulator, characterized in that: include: Steam power cycle power generation subsystem, molten salt heat storage subsystem and steam energy storage subsystem; The steam power cycle power generation subsystem includes: a steam generator, a steam turbine, a generator, a condenser, a low-pressure heater, a deaerator and a high-pressure heater; the molten salt heat storage subsystem includes: a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat exchanger, a molten salt steam heat exchanger, a first valve, a second valve and a third valve; the steam energy storage subsystem includes: a steam accumulator, a fourth valve, a fifth valve and a sixth valve; the main steam extraction at the steam generator outlet is connected to the steam turbine and the molten salt steam heat exchanger respectively; the reheated steam at the steam generator outlet is connected to the steam turbine; the generator is coaxially connected to the steam turbine; the first-stage extraction of the steam turbine is connected to the high-pressure heater and the steam generator respectively; the second-stage extraction of the steam turbine is connected to the deaerator; the third-stage extraction of the steam turbine is connected to the low-pressure heater; the exhaust steam of the steam turbine is connected to the condenser; the condenser is connected to the low-pressure heater; the low-pressure heater is connected to the water side of the deaerator inlet; the water side outlet of the deaerator is connected to the high-pressure heater; the high-pressure heater is connected to the steam generator; the high-temperature molten salt tank outlet is connected to the molten salt heat exchanger; the molten salt outlet of the molten salt heat exchanger is connected to the inlet of the low-temperature molten salt tank; the outlet of the low-temperature molten salt tank is connected to the molten salt steam heat exchanger; the molten salt outlet of the molten salt steam heat exchanger is connected to the inlet of the high-temperature molten salt tank; a first valve is provided on the connecting pipeline between the steam generator and the molten salt steam heat exchanger; a second valve is provided on the connecting pipeline between the low-temperature molten salt tank and the molten salt steam heat exchanger; a third valve is provided on the connecting pipeline between the high-temperature molten salt tank and the molten salt heat exchanger; the steam outlet of the molten salt steam heat exchanger is connected to the steam inlet of the steam accumulator; a fourth valve is provided on the connecting pipeline between the molten salt steam heat exchanger and the steam accumulator; a fifth valve is provided on the steam outlet pipeline of the steam accumulator; the feed water inlet of the steam accumulator is connected to the feed water pump; a sixth valve is provided on the feed water inlet pipeline of the steam accumulator; When the unit is running at low load or reducing load, the first valve and the second valve are opened, and the third valve is closed, so that the steam at the steam generator outlet is exchanged with the low-temperature molten salt in the molten salt steam heat exchanger, and part of the heat is stored in the high-temperature molten salt tank; the fourth valve is opened to inject the steam at the molten salt steam heat exchanger outlet into the steam accumulator for steam storage; When the unit increases load or needs to supply heat, open the third valve and close the second valve to release the heat stored in the high-temperature molten salt tank and heat the working medium through the molten salt heat exchanger; open the fifth valve and close the fourth valve to release the steam in the steam accumulator as a steam source to replace the heat recovery steam or supply heat; open the sixth valve, and the feed water pump will inject part of the feed water into the steam accumulator to ensure the stability of the liquid level; By adjusting the opening of the first valve, the flow rate of the extracted main steam and the load reduction rate are controlled; By adjusting the opening of the sixth valve, the amount of water in the steam accumulator is controlled, thereby adjusting the steam pressure and temperature at the steam accumulator outlet; The steam outlet of the steam accumulator is connected to the third-stage high-pressure heater and the deaerator respectively; The steam accumulator operates at sliding pressure, and the operating pressure range is 1.0-2.7MPa.

2. An energy storage peak regulation system integrating molten salt heat storage and steam accumulator, characterized in that: include: Steam power cycle power generation subsystem, molten salt heat storage subsystem and steam energy storage subsystem; The steam power cycle power generation subsystem includes: a steam generator, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a condensate pump, a five-stage low-pressure heater group, a deaerator, a high-pressure water pump and a three-stage high-pressure heater group; the five-stage low-pressure heater group includes a first-stage low-pressure heater, a second-stage low-pressure heater, a third-stage low-pressure heater, a fourth-stage low-pressure heater and a fifth-stage low-pressure heater connected in sequence; the three-stage high-pressure heater group includes a first-stage high-pressure heater, a second-stage high-pressure heater and a third-stage high-pressure heater connected in sequence; The molten salt heat storage subsystem includes: a high-temperature molten salt tank, a low-temperature molten salt tank, a fourth valve, a high-temperature molten salt pump, a molten salt feed water heat exchanger, a third valve, a low-temperature molten salt pump, a molten salt steam heat exchanger, a first valve and a second valve; The steam energy storage subsystem comprises: a steam accumulator, a fifth valve, a seventh valve, a feed water pump and a sixth valve; The main steam extraction at the steam generator outlet is connected to the high-pressure cylinder and the molten salt steam heat exchanger respectively; the reheated steam at the steam generator outlet is connected to the medium-pressure cylinder and the low-pressure cylinder respectively; the generator is coaxially connected to the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder; the high-pressure cylinder extraction is connected to the first-stage high-pressure heater; the high-pressure cylinder exhaust is connected to the steam generator and the second-stage high-pressure heater respectively; the medium-pressure cylinder extraction is connected to the third-stage high-pressure heater, the deaerator and the first-stage low-pressure heater respectively; the low-pressure cylinder extraction is connected to the second-stage low-pressure heater, the third-stage low-pressure heater, the fourth-stage low-pressure heater and the fifth-stage low-pressure heater respectively; the low-pressure cylinder exhaust is connected to the condenser; the condenser is connected to the condensate pump; the condensate pump is connected to the five-stage low-pressure heater group; the first-stage low-pressure heater is connected to the water side inlet of the deaerator; the water side outlet of the deaerator is connected to the high-pressure water pump; the high-pressure water pump is connected to the three-stage high-pressure heater group; the first-stage high-pressure heater is connected to the steam generator; The outlet of the high-temperature molten salt tank is connected to the molten salt water feed heat exchanger through a high-temperature molten salt pump; the molten salt outlet of the molten salt water feed heat exchanger is connected to the inlet of the low-temperature molten salt tank; the outlet of the low-temperature molten salt tank is connected to the molten salt steam heat exchanger through a low-temperature molten salt pump; the molten salt outlet of the molten salt steam heat exchanger is connected to the inlet of the high-temperature molten salt tank; the water side inlet of the molten salt water feed heat exchanger is connected to a high-pressure water pump; the water side outlet of the molten salt water feed heat exchanger is connected to a steam generator; a first valve is provided on the connecting pipeline between the steam generator and the molten salt steam heat exchanger; a second valve is provided on the connecting pipeline between the high-pressure water pump and the molten salt water feed heat exchanger; a third valve is provided on the connecting pipeline between the low-temperature molten salt tank and the molten salt steam heat exchanger; a fourth valve is provided on the connecting pipeline between the high-temperature molten salt tank and the molten salt water feed heat exchanger; The steam outlet of the molten salt steam heat exchanger is connected to the steam inlet of the steam accumulator; the feed water pump is connected to the feed water inlet of the steam accumulator; the steam outlet of the steam accumulator is respectively connected to the third-stage high-pressure heater and the deaerator; a fifth valve is provided on the connecting pipeline between the molten salt steam heat exchanger and the steam accumulator; a sixth valve is provided on the connecting pipeline between the steam accumulator and the third-stage high-pressure heater and the deaerator; a seventh valve is provided on the connecting pipeline between the feed water pump and the steam accumulator; When the unit is running at low load or reducing load, open the first valve and the third valve, close the fourth valve, and exchange heat between the main steam at the steam generator outlet and the low-temperature molten salt in the molten salt steam heat exchanger, and store part of the heat in the high-temperature molten salt tank; open the fifth valve to inject the steam at the outlet of the molten salt steam heat exchanger into the steam accumulator for steam storage; When the unit increases load, open the fourth valve and the second valve, close the third valve, release the heat stored in the high-temperature molten salt tank, and heat the feed water through the molten salt feed water heat exchanger; open the sixth valve, close the fifth valve, release the steam in the steam accumulator as the heating steam for the third-stage high-pressure heater and deaerator; open the seventh valve, and the feed water pump injects part of the feed water into the steam accumulator; By adjusting the opening of the first valve, the flow rate of the extracted main steam and the load reduction rate are controlled; By adjusting the opening of the seventh valve, the amount of water in the steam accumulator is controlled, thereby adjusting the steam pressure and temperature at the steam accumulator outlet; The steam outlet of the steam accumulator is connected to the third-stage high-pressure heater and the deaerator respectively; The steam accumulator operates at sliding pressure, and the operating pressure range is 1.0-2.7MPa.

3. The energy storage peak regulation system integrating molten salt heat storage and steam accumulator according to claim 1 or 2, characterized in that: The steam power cycle power generation subsystem includes a coal-fired power generation subsystem, a biomass power generation subsystem, a garbage combustion power generation subsystem, a nuclear power generation subsystem and a geothermal power generation subsystem.

4. The energy storage peak regulation system integrating molten salt heat storage and steam accumulator according to claim 1 or 2, characterized in that: The operating temperature of the high temperature molten salt tank is 565°C.

5. The energy storage peak regulation system integrating molten salt heat storage and steam accumulator according to claim 1 or 2, characterized in that: The operating temperature of the low-temperature molten salt tank is 290°C.

6. The energy storage peak regulation system integrating molten salt heat storage and steam accumulator according to claim 1 or 2, characterized in that: The type of the molten salt is binary salt.

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