Fused salt heat storage and solar energy coupled industrial steam supply peak regulation system and method

Abstract

The invention relates to the technical field of multi-energy complementary power generation, and discloses an industrial steam supply peak shaving system and method coupling fused salt heat storage and solar energy, and the industrial steam supply peak shaving system comprises a coal-fired power generation system and an industrial steam supply system; in the heat storage mode, the boiler, the steam cooler and the condenser are sequentially connected; in the heat release mode, the high-pressure heater, the primary feed water heater and the low-pressure cylinder are sequentially connected through pipelines; and the feed pump, the secondary feed water heater and the boiler are connected in sequence. In the low ebb of the electrical load, solar energy is used for heating fused salt to store heat, and part of high-temperature steam is extracted from steam-water circulation of the improved coal-fired power generation system to store the heat in a heat storage device and does not enter a steam turbine for power generation; the power load output is adjusted by adjusting the thermal load output of the thermodynamic system in the power generation process, and load decoupling of the boiler and the steam turbine is achieved. And in the electrical load peak, the stored heat energy is released back to steam-water circulation, and the electrical load of the coal-fired power generation system is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-energy complementary power generation, and in particular to an industrial steam supply peak regulation system and method coupled with molten salt heat storage and solar energy. Background Art

[0002] As an important carrier for achieving the "dual carbon" goal and building a new power system, new energy will become the main source of power increase in my country for a long time in the future. However, due to the phenomenon of "abandoning wind and light", the peak-shaving and frequency-regulating tasks faced by thermal power units are becoming increasingly arduous. In recent years, the state has continuously issued relevant policies to encourage the innovation of new energy storage technologies and promote the development of new energy storage industries. Especially after the introduction of the electricity spot trading policy, the demand for thermal power units coupled with energy storage equipment has increased. The application of energy storage systems can effectively solve the shortage of power supply during peak hours, reduce the power supply pressure of the power grid, and play a role in peak-shaving and valley-filling. In addition, the energy storage process adjusts the output curve of renewable energy generators, reduces the risks brought by the randomness and uncontrollability of their own power generation to the stable operation of the power grid, and avoids the additional energy consumption of conventional power generation devices as backup power. When the power grid is working normally, the peak-valley electricity price difference can also be used to create additional income for the power station. Therefore, the energy storage system is considered to be one of the most effective ways to solve the peak-shaving problem of the power system.

[0003] Molten salt energy storage technology has good safety, no geographical restrictions, a wide range of energy storage capacity, relatively low cost, fast response speed, high power and energy density, etc. The industry has a high degree of recognition of molten salt energy storage technology. Compared with other energy storage technologies, molten salt heat storage has the characteristics of large-scale, long-term, safe and stable, and not restricted by site selection. It is one of the most promising energy storage technologies in building future new power systems.

[0004] The patent document with publication number CN211924391U proposes a solar thermal power generation electric heat conversion peak-shaving and frequency modulation system, which is characterized by using the wind curtailment and power restriction of surrounding wind farms to heat the molten salt in the heat storage module. Considering that the wind-solar-electricity conversion efficiency cannot reach 100%, the energy utilization efficiency of heating molten salt with electricity is low, resulting in high-quality electricity being converted into low-quality heat, and the need to add electric boilers, which is costly. The use of steam to heat molten salt is appropriate from the perspective of energy cascade utilization.

[0005] Patent document with publication number CN109958593A proposes a solar-coal-fired coupled flexible power generation system, which is characterized by arranging a heat storage medium heater in the boiler flue and using a heat storage medium tank for peak load regulation. However, since the heat storage heater is arranged in the boiler, the system requires a large-scale transformation of the existing coal-fired unit structure and is difficult to promote.

[0006] The patent document with publication number CN116826800A proposes a flexible power generation system that complements light, coal and energy storage. Its characteristics are that the load is increased by increasing the opening of the feed water regulating valve. After the feed water is heated, it can only meet the water working medium inlet temperature requirement of the boiler, and the energy cascade utilization is not sufficient; and when solar energy is insufficient, it is impossible to ensure that the working temperature of the heat transfer oil meets the requirements of safe heating of feed water and heating of molten salt.

[0007] The patent document with publication number CN202210637647X proposes a solar-coal coupled power generation system and method. The method only provides an operating method for whether there is sufficient solar energy, and does not provide a specific implementation method for increasing and reducing the load of the power grid, and cannot respond well to the peak-shaving needs of the power grid.

[0008] Therefore, how to provide a power generation system and method that couples molten salt heat storage with thermal power units for peak regulation while absorbing renewable energy, so that each subsystem is independent of each other, and fully utilizes solar energy and steam thermal energy without causing large-scale changes to the entire coal-fired unit to achieve energy cascade utilization has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0009] Therefore, the technical problem to be solved by the present invention is to overcome the defects existing in the above-mentioned prior art, thereby providing a technical solution for achieving variable load according to the needs of the power grid, specifically: a coal-fired power generation system and method based on molten salt heat storage coupled with solar energy.

[0010] A coal-fired power generation system based on molten salt heat storage coupled with solar energy, comprising: An improved coal-fired power generation system consisting of a basic coal-fired power generation system and a feedwater pump; A solar thermal storage system consisting of a solar collector and a solar heat exchanger connected in a heat transfer oil circulation manner, and a solar heat exchanger and a solar bypass molten salt pump connected in a pipeline; And, a molten salt heat storage system composed of a high-temperature molten salt storage tank, a high-temperature molten salt pump, a primary feedwater heater, a secondary feedwater heater, a low-temperature molten salt storage tank, a low-temperature molten salt pump, a steam cooler and a high-temperature molten salt storage tank connected in sequence; The low-temperature molten salt storage tank, the solar bypass molten salt pump, the solar heat exchanger and the high-temperature molten salt storage tank are connected in sequence; In the heat storage mode: the boiler, the steam cooler and the condenser of the basic coal-fired power generation system are connected in sequence by pipelines; In the heat release mode: the high-pressure heater, the first-stage feedwater heater and the low-pressure cylinder of the basic coal-fired power generation system are connected by pipelines in sequence; the feedwater pump, the second-stage feedwater heater and the boiler of the basic coal-fired power generation system are connected by pipelines in sequence; The opening / closing of the heat storage process and the heat release process are controlled by regulating valves or shut-off valves on each connecting pipeline.

[0011] Preferably, the basic coal-fired power generation system comprises: a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a condensate pump, a low-pressure heater, a deaerator and a high-pressure heater; The boiler steam outlet, the high pressure cylinder and the boiler reheat steam inlet are connected by pipelines in sequence; The boiler reheat steam outlet, the intermediate pressure cylinder, the low pressure cylinder and the generator are connected in sequence so that the power output end is connected to the power grid; The low-pressure cylinder, condenser, condensate pump, low-pressure heater, deaerator, feed water pump and high-pressure heater are connected in sequence through pipelines, and the main outlet of the high-pressure heater is connected to the boiler feed water inlet through a pipeline; The steam outlet of the high-pressure cylinder is connected to the reheat steam inlet of the boiler; The high-pressure cylinder steam outlet is connected to the high-pressure heater.

[0012] Preferably, a steam extraction bypass point is provided on the pipeline connecting the intermediate pressure cylinder inlet and the boiler outlet, and is connected to the steam cooler, so that the steam cooler can be used to extract part of the reheated steam through the steam extraction bypass point during the electricity off-peak period to reduce the power generation of the system; A feedwater pump bypass point is set at the outlet of the feedwater pump and connected to the secondary feedwater heater. During the peak period of electricity use, the secondary feedwater heater can extract part of the feedwater from the feedwater pump bypass point to reduce the steam extraction of the steam turbine; A high-pressure heater pumping bypass point is set at the outlet of the high-pressure heater and connected to the first-stage feedwater heater so that when the load is increased, part of the feedwater output by the high-pressure heater directly enters the first-stage feedwater heater to generate steam that enters the low-pressure cylinder, thereby increasing the steam intake of the low-pressure cylinder.

[0013] A coal-fired power generation method based on molten salt heat storage coupled with solar energy is implemented using the coal-fired power generation system; the method comprises the following steps: Determine power demand; When the power load is at a low point, the heat storage mode is turned on; the connecting pipes between the boiler, steam cooler and condenser of the basic coal-fired power generation system are opened, and closed at other times; When the electricity load is at its peak, the heat release mode is turned on; the high-pressure heater, the first-level feedwater heater and the low-pressure cylinder of the basic coal-fired power generation system are connected by pipelines in sequence; the pipelines between the feedwater pump, the second-level feedwater heater and the boiler of the basic coal-fired power generation system are opened, and closed at other times.

[0014] Preferably, when the power load is low: Part of the reheated steam output by the boiler is extracted through the steam extraction bypass point and transmitted to the steam cooler. The reheated steam releases heat through the steam cooler and then merges into the low-pressure cylinder exhaust steam; The cold molten salt in the low-temperature molten salt tank passes through the steam cooler to absorb heat and obtain the heat of the reheated steam. The temperature rises and is stored in the high-temperature molten salt tank. When the solar energy is sufficient, the heat transfer oil is heated by the solar collector, and part of the cold molten salt in the low-temperature molten salt tank passes through the solar heat exchanger to absorb the heat of the heat transfer oil and is stored in the high-temperature molten salt tank, thereby increasing the storage capacity of the high-temperature molten salt.

[0015] Based on the above technical solution, the following effects are achieved: during the low electricity consumption period, when the coal-fired power generation system needs to reduce the load quickly, the extraction amount of reheated steam to the industrial steam supply manifold is increased, so that more steam turbine extraction steam can enter the industrial steam supply manifold, thereby reducing the output of the coal-fired power generation system.

[0016] Preferably, when the power load is at its peak: The high-temperature molten salt in the high-temperature molten salt tank releases heat through the primary feedwater heater and the secondary feedwater heater. The cooled molten salt returns to the low-temperature molten salt tank for storage. Part of the feedwater at the outlet of the feedwater pump enters the secondary feedwater heater through the feedwater pump bypass point to absorb the heat of the high-temperature molten salt. After absorbing the heat, it enters the boiler to replace the high-pressure heater, reduce the steam extraction of the steam turbine, and increase the power generation of the unit when the load is increased; Part of the feed water at the outlet of the high-pressure heater enters the first-stage feed water heater to absorb the heat of the high-temperature molten salt, generate steam and enter the low-pressure cylinder, thereby increasing the working capacity of the low-pressure cylinder.

[0017] Preferably, the outlet of the solar bypass molten salt pump is connected to the low-temperature side molten salt inlet of the solar heat exchanger through a pipeline, and the flow of low-temperature molten salt entering the solar heat exchanger from the low-temperature molten salt storage tank is controlled by the solar bypass molten salt pump; the low-temperature side outlet of the solar heat exchanger is connected to the inlet of the high-temperature molten salt tank.

[0018] Based on the above technical solution, the following effects are achieved: during peak electricity consumption periods, when the coal-fired power generation system needs to quickly increase its load, the amount of steam extracted from the reheated steam to the industrial steam supply manifold is reduced, so that the steam that should have been supplied will enter the steam turbine to do work, thereby rapidly increasing the output of the coal-fired power generation system. At the same time, the molten salt heat storage system releases heat, and the stored heat of the molten salt is transferred to part of the feed water through the first-stage feed water heater. The feed water evaporates into steam and enters the industrial steam supply manifold, thereby ensuring the industrial steam supply.

[0019] An industrial steam supply peak-shaving system coupled with molten salt heat storage and solar energy, comprising: a coal-fired power generation system and an industrial steam supply system; In the industrial steam supply system: one path of the industrial steam supply manifold is connected to the medium pressure cylinder steam inlet pipeline, and the other path is connected to the first-stage feedwater heater outlet steam pipeline.

[0020] An industrial steam supply peak-shaving method coupling molten salt heat storage and solar energy is implemented by an industrial steam supply peak-shaving system; the industrial steam supply peak-shaving method comprises the following steps: One line of the industrial steam supply manifold is connected to the steam inlet pipe of the medium pressure cylinder, and the other line is connected to the steam outlet pipe of the first-stage feedwater heater; Therefore, the steam extraction amount from the reheat steam to the industrial steam supply header is controlled based on the valves on the connecting pipes between the industrial steam supply header and the intermediate pressure cylinder; When the steam extraction amount of reheat steam to the industrial steam supply header is reduced, the reheat steam enters the steam turbine to perform work, thereby increasing the output of the coal-fired power generation system; When the extraction amount of reheat steam to the industrial steam supply header is increased, the amount of steam extracted from the steam turbine entering the industrial steam supply header is increased to reduce the output of the coal-fired power generation system.

[0021] The technical solution of the present invention has the following advantages: (1) The system provided by the present invention utilizes the steam cooler to store the sensible heat of steam in molten salt during the low electricity consumption period, thereby reducing the online electricity consumption of the unit, improving the peak load regulation capability of the system, improving the flexibility of the thermal power unit, and making full use of solar energy. The system has the characteristics of high system efficiency, large scale, long time, safety and stability, and low requirements on engineering site conditions; (2) The system provided by the present invention utilizes solar energy resources and does not require the use of fossil fuels. It has the characteristics of cleanliness and pollution-free, and is environmentally friendly and pollution-free; (3) The system provided by the present invention can store heat in a large capacity, for a long time and at a low cost, thus achieving deep peak regulation of the unit. At the same time, the stored heat energy can heat the boiler feed water, reduce the extraction of high-pressure steam, and reduce the heat consumption of the unit, thus having good economic benefits.

[0022] (4) The system provided by the present invention can better realize the cascade utilization of energy, so that more steam enters the low-pressure cylinder, increasing the working capacity of the low-pressure cylinder, further improving the peak capacity of the unit, reducing coal consumption, and facilitating primary frequency regulation.

[0023] (5) After the feed water is heated by the present invention, it not only enters the boiler, but also generates superheated steam which enters the low-pressure cylinder. This not only further improves the peak-shaving capability, but also allows more steam to enter the low-pressure cylinder, and can balance the pressure and temperature distribution inside the turbine, reduce vibration and thermal stress during operation, and thus extend the service life of the turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1It is a structural schematic diagram of the coal-fired power generation system based on molten salt heat storage coupled with solar energy of the present invention; Figure 2 It is a schematic diagram of the heat storage process of the coal-fired power generation system based on molten salt heat storage coupled with solar energy of the present invention; Figure 3 It is a schematic diagram of the heat release process of the coal-fired power generation system based on molten salt heat storage coupled with solar energy of the present invention; Figure 4 It is a structural schematic diagram of the industrial steam supply peak-shaving system coupling molten salt heat storage and solar energy of the present invention.

[0026] Description of reference numerals: 1- boiler, 2- high-pressure cylinder, 3- medium-pressure cylinder, 4- low-pressure cylinder, 5- generator, 6- condenser, 7- condensate pump, 8- low-pressure heater, 9- deaerator, 10- feed water pump, 11- high-pressure heater, 12- solar collector, 13- solar heat exchanger, 14- solar bypass molten salt pump, 15- high-temperature molten salt storage tank, 16- high-temperature molten salt pump, 17- primary feed water heater, 18- secondary feed water heater, 19- low-temperature molten salt storage tank, 20- low-temperature molten salt pump, 21- steam cooler, 22- industrial steam supply manifold. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Example 1 This embodiment discloses a coal-fired power generation system based on molten salt heat storage coupled with solar energy, such as Figure 1 As shown, including: An improved coal-fired power generation system consisting of a basic coal-fired power generation system and a feedwater pump 10; A solar thermal storage system consisting of a solar collector 12 and a solar heat exchanger 13 connected by a heat transfer oil circulation, and a solar heat exchanger 13 and a solar bypass molten salt pump 14 connected by a pipeline; And, a molten salt heat storage system consisting of a high-temperature molten salt storage tank 15, a high-temperature molten salt pump 16, a primary feedwater heater 17, a secondary feedwater heater 18, a low-temperature molten salt storage tank 19, a low-temperature molten salt pump 20, a steam cooler 21 and the high-temperature molten salt storage tank 15 connected in sequence; The low temperature molten salt storage tank 19, the solar bypass molten salt pump 14, the solar heat exchanger 13 and the high temperature molten salt storage tank 15 are connected in sequence; In the heat storage mode: the boiler 1 of the basic coal-fired power generation system, the steam cooler 21 and the condenser 6 of the basic coal-fired power generation system are connected in sequence by pipelines; In the heat release mode: the high-pressure heater 11, the first-level feedwater heater 17 and the low-pressure cylinder 4 of the basic coal-fired power generation system are connected in sequence through pipelines; the feedwater pump 10, the second-level feedwater heater 18 and the boiler 1 of the basic coal-fired power generation system are connected in sequence through pipelines; The opening / closing of the heat storage process and the heat release process are controlled by regulating valves or shut-off valves on each connecting pipeline.

[0032] Specifically: The basic coal-fired power generation system includes: boiler 1, high-pressure cylinder 2, medium-pressure cylinder 3, low-pressure cylinder 4, generator 5, condenser 6, condensate pump 7, low-pressure heater 8, deaerator 9 and high-pressure heater 11; The steam outlet of the boiler of the coal-fired power generation system, the high-pressure cylinder 2 and the reheat steam inlet of the boiler 1 are connected by pipelines in sequence; specifically: the steam outlet of the boiler is connected to the inlet of the high-pressure cylinder 2 through a pipeline, and the outlet of the high-pressure cylinder 2 is connected to the reheat steam inlet of the boiler 1 through a pipeline; The boiler reheat steam outlet, the medium pressure cylinder 3, the low pressure cylinder 4 and the generator 5 are connected in sequence so that the power output end is connected to the power grid; the medium pressure cylinder 3 has four outlets and one inlet; the boiler reheat steam outlet is connected to the inlet of the medium pressure cylinder 3. The first outlet of the medium pressure cylinder 3 is connected to the low pressure cylinder 4; the main shaft of the low pressure cylinder 4 is connected to the generator 5 so that the power output end is connected to the power grid; The low-pressure cylinder 4, the condenser 6, the condensate pump 7, the low-pressure heater 8, the deaerator 9, the feed water pump 10 and the high-pressure heater 11 are connected in sequence through pipelines, and the main outlet of the high-pressure heater 11 is connected to the boiler feed water inlet through a pipeline; The steam outlet of the high pressure cylinder 2 is connected to the boiler reheat steam inlet; The steam outlet of the high-pressure cylinder 2 is communicated with the high-pressure heater 11 .

[0033] As an improved implementation, in this embodiment, the low-pressure heater 8 and the high-pressure heater 11 are both in the form of multi-stage heating units connected in series, such as Figure 1 In this embodiment, the high-pressure heater 11 is level 3 and the low-pressure heater 8 is level 4; and the pipeline connection point between the high-pressure heater 11 and the secondary water supply heater 18 is located at the inlet or outlet of any high-pressure heating unit, and water is taken at a single point or multiple points to achieve adjustable water intake temperature and flow.

[0034] Specifically: in the high-pressure heater 11: the third high-pressure heating unit and the second high-pressure heating unit are connected in a loop, and the second high-pressure heating unit and the first high-pressure heating unit are connected in a loop; the first high-pressure heating unit is connected to the boiler 1; the third heating unit is connected to the feed water pump 10, the second outlet of the medium-pressure cylinder 3 and the deaerator 9 respectively; Furthermore, in this embodiment, the high-pressure cylinder 2 has two steam outlets, one of which is connected to the first high-pressure heating unit; the other steam outlet is connected to the boiler reheat steam inlet, and a branch is opened on the connecting pipeline to connect to the second high-pressure heating unit of the high-pressure heater 11; At the same time, in the low-pressure heater 8: the fourth low-pressure heating unit and the third low-pressure heating unit are cyclically connected; the third low-pressure heating unit and the second low-pressure heating unit are cyclically connected, and the second low-pressure heating unit and the first low-pressure heating unit are cyclically connected; the first low-pressure heating unit is connected to the boiler 1; The fourth low-pressure heating unit is connected to the fourth outlet of the medium-pressure cylinder 3 and the deaerator 9 respectively; the third outlet of the medium-pressure cylinder 3 is connected to the deaerator 9; In this embodiment, the low-pressure cylinder 4 has three steam outlets, which are respectively adapted to be connected to the third low-pressure heating unit, the second low-pressure heating unit and the first low-pressure heating unit; the first low-pressure heating unit is also connected to the condensate pump 7 and the condenser 6; like Figure 1 As an improved implementation, in this embodiment, a steam extraction bypass point is set on the pipeline connecting the inlet of the intermediate pressure cylinder 3 and the outlet of the boiler 1, and is connected to the steam cooler 21, so that the steam cooler 21 can extract part of the reheated steam through the steam extraction bypass point during the electricity off-peak period to reduce the power generation of the system; A feedwater pump bypass point is provided at the outlet of the feedwater pump 10 and connected to the secondary feedwater heater 18, so that during the peak period of electricity use, the secondary feedwater heater 18 can extract part of the feedwater from the feedwater pump bypass point to reduce the steam extraction amount of the steam turbine; A high-pressure heater water pumping bypass point is set at the outlet of the high-pressure heater 11 and connected to the first-stage feed water heater 17, so that when the load is increased, part of the feed water output by the high-pressure heater 11 directly enters the first-stage feed water heater 17 to generate steam that enters the low-pressure cylinder 4, thereby increasing the steam intake of the low-pressure cylinder 4.

[0035] It should be noted that, in order to accurately control the operation of each component in the system, a regulating valve or a shut-off valve is arranged on the passage connected by the pipeline in this embodiment; Take part of the pipeline as an example: The steam side inlet of the steam cooler 21 is connected to the boiler reheat steam outlet through a pipeline, a regulating valve is arranged on the pipeline, the steam side outlet of the steam cooler 21 is connected to the steam inlet of the condenser 6, a shut-off valve is arranged on the steam inlet pipeline of the steam cooler 21, the condensate outlet of the steam cooler 21 is connected to the inlet of the condenser 6 after being collected through the pipeline, the condensate pipeline is led to the condenser 6, a shut-off valve is arranged on the condensate outlet pipeline of the steam cooler 21, and the sensible heat of the steam is stored in the molten salt through the steam cooler 21; the water side inlet of the primary feed water heater 17 It is connected to the bypass point of the high-pressure heater 11 through a pipeline, and a regulating valve is arranged on the pipeline. A pressure reducer is arranged on the steam outlet pipeline of the first-level feedwater heater 17. The feedwater is heated to generate superheated steam, which enters the inlet of the low-pressure cylinder 4 after pressure reduction, matching the steam inlet parameters of the low-pressure cylinder 4. The water side inlet of the second-level feedwater heater 18 is connected to the inlet of the high-pressure heater 11 through a pipeline, and a regulating valve is arranged on the pipeline. The water side outlet of the second-level feedwater heater 18 is connected to the boiler feedwater inlet through a pipeline, and a shut-off valve is arranged on the pipeline. Each pipeline is equipped with a regulating valve to adjust the flow rate of the corresponding working medium.

[0036] Example 2 This embodiment discloses a coal-fired power generation method based on molten salt heat storage coupled with solar energy, characterized in that the coal-fired power generation system in claim 3 is adopted; the method comprises the following steps: Determine power demand; When the power load is low, Figure 2 Turn on the heat storage mode; the connecting pipes between the boiler 1 of the basic coal-fired power generation system, the steam cooler 21 and the condenser 6 of the basic coal-fired power generation system are opened, and closed at other times; When the power load is at its peak, Figure 3 Turn on the heat release mode; the high-pressure heater 11, the first-level feed water heater 17 and the low-pressure cylinder 4 of the basic coal-fired power generation system are connected by pipelines in sequence; the pipeline between the feed water pump 10, the second-level feed water heater 18 and the boiler 1 of the basic coal-fired power generation system is opened, and closed at other times.

[0037] Specifically: When the power load is low: A portion of the reheated steam outputted from the boiler 1 is extracted through the steam extraction bypass point and transmitted to the steam cooler 21. The reheated steam is released through the steam cooler 21 and then merged into the exhaust steam of the low-pressure cylinder 4; The cold molten salt in the low-temperature molten salt tank 19 absorbs heat through the steam cooler 21 to obtain the heat of the reheated steam, and the temperature is increased and stored in the high-temperature molten salt tank 15; when the solar energy is sufficient, the heat transfer oil is heated by the solar collector 12, and part of the cold molten salt in the low-temperature molten salt tank 19 absorbs the heat of the heat transfer oil through the solar heat exchanger 13, and is stored in the high-temperature molten salt tank 15, thereby increasing the storage capacity of the high-temperature molten salt.

[0038] When the power load is at its peak: The high-temperature molten salt in the high-temperature molten salt tank 15 releases heat through the primary feedwater heater 17 and the secondary feedwater heater 18. The cooled molten salt returns to the low-temperature molten salt tank 19 for storage. Part of the feedwater at the outlet of the feedwater pump 10 enters the secondary feedwater heater 18 through the feedwater pump bypass point to absorb the heat of the high-temperature molten salt. After absorbing the heat, it enters the boiler 1 to replace the high-pressure heater 11, thereby reducing the steam extraction of the steam turbine and increasing the power generation of the unit when the load is increased. Part of the feed water at the outlet of the high-pressure heater 11 enters the first-stage feed water heater 17 to absorb the heat of the high-temperature molten salt, generating steam that enters the low-pressure cylinder 4, increasing the working capacity of the low-pressure cylinder 4, further improving the top peak capacity of the unit, and is also beneficial to primary frequency regulation.

[0039] In addition, in the present embodiment, the outlet of the solar bypass molten salt pump 14 is connected to the low-temperature side molten salt inlet of the solar heat exchanger 13 through a pipeline, and the solar bypass molten salt pump 14 controls the flow of low-temperature molten salt entering the solar heat exchanger 13 from the low-temperature molten salt storage tank 19; the low-temperature side outlet of the solar heat exchanger 13 is connected to the inlet of the high-temperature molten salt tank 15.

[0040] In the molten salt heat storage system, the outlet of the high-temperature molten salt storage tank 15 is connected to the inlet of the high-temperature molten salt pump 16 through a molten salt pipeline, and the high-temperature molten salt flow rate entering the molten salt side of the first-level feed water heater 17 and the second-level feed water heater 18 from the high-temperature molten salt storage tank 15 is controlled by the high-temperature molten salt pump 16; the molten salt side outlet of the first-level feed water heater 17 is connected to the molten salt side inlet of the second-level feed water heater 18 through a molten salt pipeline, the molten salt side outlet of the second-level feed water heater 18 is connected to the inlet of the low-temperature molten salt storage tank 19 through a molten salt pipeline, a branch of the outlet of the low-temperature molten salt storage tank 19 is connected to the inlet of the low-temperature molten salt pump 20, and the low-temperature molten salt flow rate entering the molten salt side of the steam cooler 21 from the low-temperature molten salt storage tank 19 is controlled by the low-temperature molten salt pump 20; another branch of the outlet of the low-temperature molten salt storage tank 19 is connected to the inlet of the solar bypass molten salt pump 14 through a pipeline; the high-temperature molten salt storage tank 15 adopts a single hot molten salt storage tank or multiple hot molten salt storage tanks in series, and the low-temperature molten salt storage tank 19 adopts a single cold molten salt storage tank or multiple cold molten salt storage tanks in series.

[0041] It should be noted that part of the feed water at the outlet of the feed water pump 10 enters the secondary feed water heater 18 to absorb the heat of the high-temperature molten salt, and then enters the boiler 1 after absorbing the heat, replacing the high-pressure heater 11 to reduce the steam extraction of the steam turbine. At the same time, part of the feed water at the outlet of the high-pressure heater 11 enters the primary feed water heater 17 to generate steam and enter the low-pressure cylinder 4, increasing the working capacity of the low-pressure cylinder 4, and increasing the power generation of the unit when the load is increased; the system provided in this embodiment can store heat in a large capacity, for a long time, and at a low cost. When the electricity consumption is low, the sensible heat of the steam is stored in the molten salt through the steam cooler 21, reducing the online power of the unit, realizing deep peak regulation of the unit, improving the flexibility of the thermal power unit, and making full use of solar energy. The heat energy stored during the peak electricity consumption heats the boiler 1 feed water, reducing the high-pressure heating steam extraction, reducing the heat consumption of the unit, and having good economic benefits; the system utilizes solar energy resources, does not require the use of fossil fuels, has the characteristics of cleanness and pollution-free, is environmentally friendly, and pollution-free; it has the characteristics of high system efficiency, large scale, long time, safety and stability, and low requirements for engineering address conditions.

[0042] Example 3 like Figure 4 This embodiment further discloses an industrial steam supply peak-shaving system coupled with molten salt heat storage and solar energy on the basis of embodiment 1, including: the coal-fired power generation system and the industrial steam supply system of embodiment 1; In the industrial steam supply system: the industrial steam supply manifold 22 is connected to the steam inlet pipe of the medium pressure cylinder 3 on one side, and is connected to the outlet steam pipe of the first-stage feed water heater 17 on the other side.

[0043] When the electricity load is at a low point, part of the reheated steam is extracted and enters the industrial steam supply manifold 22 through the temperature reduction and pressure reducing valve; when the electricity load is at a peak, in addition to extracting the reheated steam, part of the steam generated by the first-stage feedwater heater 17 enters the industrial steam supply manifold 22 to ensure the industrial steam supply.

[0044] Example 4 On the basis of Example 3, this example further discloses an industrial steam supply peak-shaving method coupling molten salt heat storage and solar energy, which is implemented by the industrial steam supply peak-shaving system of Example 3; the industrial steam supply peak-shaving method comprises the following steps: Since the industrial steam supply manifold 22 is connected to the steam inlet pipe of the medium pressure cylinder 3 on one side and connected to the steam outlet pipe of the first-stage feedwater heater 17 on the other side; Therefore, the extraction amount of reheated steam to the industrial steam supply header 22 is controlled based on the valve on the connecting pipeline between the industrial steam supply header 22 and the intermediate pressure cylinder 3; When the steam extraction amount of the reheated steam to the industrial steam supply header 22 is reduced, the reheated steam enters the steam turbine to perform work, so as to increase the output of the coal-fired power generation system; When the extraction amount of reheated steam to the industrial steam supply header 22 is increased, the amount of steam extracted from the steam turbine entering the industrial steam supply header is increased to reduce the output of the coal-fired power generation system.

[0045] It should be noted that during peak periods of electricity consumption, when the coal-fired power generation system needs to quickly increase its load, the amount of reheated steam extracted to the industrial steam supply manifold 22 is reduced to increase the amount of steam entering the steam turbine, and the steam turbine performs work, thereby rapidly increasing the output of the coal-fired power generation system. At the same time, the molten salt heat storage system releases heat, and the stored heat of the molten salt is transferred to part of the feed water through the first-stage feed water heater 17. The feed water evaporates into steam and enters the industrial steam supply manifold 22, thereby ensuring the industrial steam supply.

[0046] During the low electricity consumption period, when the coal-fired power generation system needs to reduce the load quickly, the extraction amount of reheated steam to the industrial steam supply manifold 22 is increased, allowing more steam turbine extraction steam to enter the industrial steam supply manifold 22, thereby reducing the output of the coal-fired power generation system.

[0047] It should be noted that the intermediate pressure cylinder, low pressure cylinder and high pressure cylinder in the field of coal-fired power generation are usually the intermediate pressure cylinder, low pressure cylinder and high pressure cylinder of the steam turbine, which will not be described in detail.

[0048] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A coal-fired power generation system based on molten salt heat storage coupled with solar energy, characterized in that: include: An improved coal-fired power generation system consisting of a basic coal-fired power generation system and a feed water pump (10); A solar thermal storage system consisting of a solar thermal collector (12) and a solar heat exchanger (13) connected by a heat transfer oil circulation, and a solar heat exchanger (13) and a solar bypass molten salt pump (14) connected by a pipeline; and a molten salt heat storage system consisting of a high-temperature molten salt storage tank (15), a high-temperature molten salt pump (16), a primary feedwater heater (17), a secondary feedwater heater (18), a low-temperature molten salt storage tank (19), a low-temperature molten salt pump (20), a steam cooler (21) and the high-temperature molten salt storage tank (15), which are sequentially connected to form a molten salt heat storage system; The low-temperature molten salt storage tank (19), the solar bypass molten salt pump (14), the solar heat exchanger (13) and the high-temperature molten salt storage tank (15) are connected in sequence; In the heat storage mode: the boiler (1), the steam cooler (21) and the condenser (6) of the basic coal-fired power generation system are connected in sequence by pipelines; In the heat release mode: the high-pressure heater (11), the first-stage feedwater heater (17) and the low-pressure cylinder (4) of the basic coal-fired power generation system are connected in sequence through pipelines; the feedwater pump (10), the second-stage feedwater heater (18) and the boiler (1) of the basic coal-fired power generation system are connected in sequence through pipelines; The opening / closing of the heat storage process and the heat release process are controlled by regulating valves or shut-off valves on each connecting pipeline.

2. The coal-fired power generation system according to claim 1, characterized in that: The basic coal-fired power generation system comprises: a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), a generator (5), a condenser (6), a condensate pump (7), a low-pressure heater (8), a deaerator (9) and a high-pressure heater (11); The boiler steam outlet, the high pressure cylinder (2) and the boiler reheat steam inlet are sequentially connected by pipelines; The boiler reheat steam outlet, the medium pressure cylinder (3), the low pressure cylinder (4) and the generator (5) are connected in sequence so that the electric energy output end is connected to the power grid; The low-pressure cylinder (4), the condenser (6), the condensate pump (7), the low-pressure heater (8), the deaerator (9), the feed water pump (10) and the high-pressure heater (11) are connected in sequence through pipelines, and the main outlet of the high-pressure heater (11) is connected to the feed water inlet of the boiler (1) through a pipeline; The high-pressure cylinder steam outlet is connected to the boiler reheat steam inlet; The high-pressure cylinder steam outlet is connected to the high-pressure heater (11).

3. The coal-fired power generation system according to claim 2, characterized in that: A steam extraction bypass point is provided on a pipeline connecting the inlet of the intermediate pressure cylinder (3) and the outlet of the boiler (1), and is connected to the steam cooler (21), so that the steam cooler (21) can be used to extract part of the reheated steam through the steam extraction bypass point during the off-peak period of electricity, thereby reducing the power generation of the system; A feedwater pump bypass point is provided at the outlet of the feedwater pump (10) and connected to the secondary feedwater heater (18), so that during the peak period of electricity use, the secondary feedwater heater (18) extracts part of the feedwater from the feedwater pump bypass point to reduce the steam extraction amount of the steam turbine; A high-pressure heater water pumping bypass point is provided at the outlet of the high-pressure heater (11) and connected to the first-stage feedwater heater (17) so that when the load is increased, part of the feedwater output by the high-pressure heater (11) directly enters the first-stage feedwater heater (17) to generate steam that enters the low-pressure cylinder (4), thereby increasing the steam intake of the low-pressure cylinder (4).

4. A coal-fired power generation method based on molten salt heat storage coupled with solar energy, characterized in that: The coal-fired power generation system described in claim 3 is used to implement the coal-fired power generation method, which comprises the following steps: Determine power demand; When the electricity load is at a low point, the heat storage mode is turned on; the connecting pipes between the boiler (1) of the basic coal-fired power generation system, the steam cooler (21) and the condenser (6) of the basic coal-fired power generation system are turned on, and are turned off at other times; When the power load is at a peak, the heat release mode is turned on; the high-pressure heater (11), the first-level feedwater heater (17) and the low-pressure cylinder (4) of the basic coal-fired power generation system are connected in sequence by pipelines; the pipelines between the feedwater pump (10), the second-level feedwater heater (18) and the boiler (1) of the basic coal-fired power generation system are turned on and closed at other times.

5. The coal-fired power generation method according to claim 4, characterized in that: When the power load is low: A portion of the reheated steam output from the boiler (1) is extracted through a steam extraction bypass point and transmitted to a steam cooler (21); the reheated steam releases heat through the steam cooler (21) and then merges into the exhaust steam of the low-pressure cylinder (4); The cold molten salt in the low-temperature molten salt tank (19) passes through the steam cooler (21) to absorb heat and obtain the heat of the reheated steam, and the temperature is increased and stored in the high-temperature molten salt tank (15); when the solar energy is sufficient, the heat transfer oil is heated by the solar collector (12), and part of the cold molten salt in the low-temperature molten salt tank (19) passes through the solar heat exchanger (13) to absorb the heat of the heat transfer oil and is stored in the high-temperature molten salt tank (15), thereby increasing the storage capacity of the high-temperature molten salt.

6. The coal-fired power generation method according to claim 4, characterized in that: When the power load is at its peak: The high-temperature molten salt in the high-temperature molten salt tank (15) releases heat through the primary feedwater heater (17) and the secondary feedwater heater (18), and the cooled molten salt is returned to the low-temperature molten salt tank (19) for storage. Part of the feedwater at the outlet of the feedwater pump (10) enters the secondary feedwater heater (18) through the feedwater pump bypass point to absorb the heat of the high-temperature molten salt, and then enters the boiler (1) to replace the high-pressure heater (11), thereby reducing the steam extraction amount of the steam turbine and increasing the power generation of the unit when the load is increased; Part of the feed water at the outlet of the high-pressure heater (11) enters the first-stage feed water heater (17) to absorb the heat of the high-temperature molten salt, generating steam that enters the low-pressure cylinder (4), thereby increasing the working capacity of the low-pressure cylinder (4).

7. The coal-fired power generation method according to claim 4, characterized in that: The outlet of the solar bypass molten salt pump (14) is connected to the low-temperature side molten salt inlet of the solar heat exchanger (13) via a pipeline, and the flow rate of the low-temperature molten salt entering the solar heat exchanger (13) from the low-temperature molten salt storage tank (19) is controlled by the solar bypass molten salt pump (14); the low-temperature side outlet of the solar heat exchanger (13) is connected to the inlet of the high-temperature molten salt tank (15).

8. An industrial steam peak-shaving system coupled with molten salt heat storage and solar energy, characterized in that: include: The coal-fired power generation system and industrial steam supply system as described in claim 3; In the industrial steam supply system: one path of the industrial steam supply manifold (22) is connected to the steam inlet pipeline of the medium-pressure cylinder (3), and the other path is connected to the steam outlet pipeline of the first-stage feedwater heater (17).

9. An industrial steam supply peak regulation method coupling molten salt heat storage and solar energy, characterized in that: The industrial steam supply peak-shaving system according to claim 8 is used for implementation; the industrial steam supply peak-shaving method comprises the following steps: One path of the industrial steam supply manifold (22) is connected to the steam inlet pipeline of the medium pressure cylinder (3), and the other path is connected to the steam outlet pipeline of the first-stage feedwater heater (17); Therefore, the amount of steam extracted from the industrial steam supply header (22) is controlled by the valve on the connecting pipe between the industrial steam supply header (22) and the intermediate pressure cylinder (3); When the steam extraction amount of the reheated steam to the industrial steam supply header (22) is reduced, the reheated steam enters the steam turbine to perform work, thereby increasing the output of the coal-fired power generation system; When the amount of steam extracted from the reheated steam to the industrial steam supply header (22) is increased, the amount of steam extracted from the steam turbine entering the industrial steam supply header is increased, so that the output of the coal-fired power generation system is reduced.

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