A thermal power plant thermal storage power generation peak regulation and frequency regulation system and working method

Abstract

The present invention discloses a thermal power plant heat storage power generation peak-shaving and frequency regulation system and working method, including a heat storage device and a unit peak-shaving and frequency regulation control unit. The heat storage device includes a heat storage medium, a peak-shaving and frequency regulation electric heater and a low-pressure heating superheat heat exchanger; the peak-shaving and frequency regulation electric heater uses the surplus power of the thermal power unit to heat the heat storage medium; the low-pressure heating superheat heat exchanger sends the superheated steam generated after heating the feed water or condensate into the thermal power unit reheater or heat storage small steam turbine. The beneficial effect of the present invention is that during the off-peak period of electricity consumption, the thermal power plant's surplus high-temperature steam, high-temperature flue gas or electricity is used to heat the heat storage medium to achieve peak-shaving and frequency regulation heat storage, thereby realizing flexible peak-shaving and frequency regulation auxiliary services of the thermal power plant.

Description

Technical Field

[0001] The present invention relates to the field of energy utilization, and in particular to a thermal storage power generation peak-shaving and frequency modulation system and a working method based on a thermal power plant. Background Art

[0002] Energy storage power stations are urgently needed to improve the efficiency, safety and economy of conventional energy generation and transmission. In order to meet the requirements of power load, the current installed power generation capacity and grid capacity are built according to the maximum demand. As the peak-to-valley difference of the grid increases, it will inevitably lead to the shutdown or low-load operation of generators during non-peak power consumption and waste of grid capacity. In 2011, the total load factor of conventional coal-fired power generation units in China was only 51.8%, and the load utilization factor of the grid was also less than 55%. Using energy storage power stations to store energy can greatly improve the actual operating efficiency of thermal power units and enhance the transmission capacity of the grid. Taking 2011 as an example, if the system is increased to 80%, it can reduce the construction of 210 million kilowatts of thermal power installed capacity and 25% of grid capacity, which is equivalent to reducing investment by 1.05 trillion yuan, and saving 30 million tons of standard coal each year.

[0003] In the past 10 years, major developed countries have launched national research programs on power energy storage systems, including the United States, Japan, the United Kingdom, the European Union and Australia. It is expected that by 2050, the capacity of the world's power energy storage system will increase from the current 3.0% (128GW) of total power generation to 10% to 15%, or even higher. As of 2011, my country's energy storage installed capacity was 17GW, accounting for about 1.6% of the country's total power installed capacity, far below the world average of 2.6%; by 2020, my country's power energy storage installed capacity needs to reach more than 70GW, accounting for 4.0% to 5.0% of the country's total power installed capacity. Existing energy storage technologies include pumped storage, compressed air energy storage (CAES), thermal storage, batteries, superconductors, flywheels and supercapacitors. By comparing these energy storage technologies, we can find that except for pumped storage, compressed air energy storage and thermal storage, the single-unit capacity of three physical energy storage technologies can reach or exceed 100MW, the other energy storage technologies are all below 10MW or even 1MW. Only these three physical energy storage technologies have low costs, not exceeding US$100 / kw·h, and have a long energy storage life.

[0004] As global energy consumption becomes increasingly tense, people are paying more and more attention to the environment. Energy shortage and environmental pollution have become important issues that affect people's lives and restrict social development. Countries around the world are working hard to develop clean new energy. As a clean, environmentally friendly and infinite natural energy, solar energy accounts for an increasingly large proportion of the energy types used by humans.

[0005] Common medium and high temperature heat storage media include steam, water, thermal oil, liquid metal, air, molten salt, etc. If medium and high temperature heat storage media can be utilized, during peak electricity consumption periods, high-temperature steam can be generated to enter the steam turbine to increase power generation. During low electricity consumption periods, electric heaters can be used to heat the heat storage medium to achieve peak-shaving and frequency-regulating heat storage, thus realizing flexible peak-shaving and frequency-regulating auxiliary services for thermal power plants. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention aims to provide a thermal storage power generation peak-shaving and frequency regulation system and a working method for a thermal power plant.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a thermal power plant heat storage power generation peak-shaving and frequency regulation system, which is arranged in a thermal power plant, wherein the thermal power plant includes a power plant boiler, a large steam turbine and a generator, and also includes a heat storage device and a unit peak-shaving and frequency regulation control unit;

[0009] The heat storage device includes a heat storage medium, a peak-shaving and frequency-modulating electric heater, and a low-pressure heating superheat exchanger;

[0010] The heat storage medium is any one of a sensible heat storage material, a latent heat storage material, and a thermochemical heat storage material;

[0011] The peak-shaving and frequency-regulating electric heater utilizes the surplus power of the peak-shaving and frequency-regulating thermal power unit to heat the heat storage medium or utilizes the high-temperature flue gas or high-temperature steam in the thermal power plant to heat the heat storage medium; the superheated steam generated by the low-pressure heating superheat exchanger arranged in the heat storage device is sent to the reheater of the thermal power unit and then enters the large steam turbine or the small heat storage steam turbine to drive the generator or small generator to generate electricity.

[0012] Furthermore, the power supply for the peak-shaving and frequency-regulating electric heater comes from the generator export bus, the plant power bus or the plant bus after the booster station, and the peak-shaving and frequency-regulating electricity of the thermal power plant is used to meet the power supply of the peak-shaving and frequency-regulating electric heater.

[0013] Furthermore, the low-pressure heater in the thermal power plant is connected to the deaerator or the condenser, and the feed water or condensate is sent to the low-pressure heating superheat exchanger arranged in the heat storage device through a low-pressure feed water pump.

[0014] Furthermore, a high-temperature flue gas heat exchanger is arranged in the heat storage device, connected to the flue gas supply and return pipeline of the power station boiler, and the high-temperature flue gas of the power station boiler is extracted to heat the heat storage medium.

[0015] Furthermore, a high-temperature steam heat exchanger is arranged in the heat storage device and connected to a high-temperature steam pipeline. The high-temperature steam comes from any one of the main steam of the power station boiler, reheated steam or large steam turbine extraction steam.

[0016] Furthermore, the sensible heat storage material of the heat storage medium includes any one of concrete, solid magnesium bricks, solid heat-resistant bricks, solid heat-resistant sand, and high-temperature resistant heat-conducting oil.

[0017] Furthermore, the latent heat storage material of the heat storage medium includes any one of high-temperature molten salts, mixed salts, metals and alloys, and the high-temperature molten salt formula includes any one or a combination of alkali metals, alkaline earth metal halides, silicates, carbonates, nitrates and phosphates.

[0018] Furthermore, the thermochemical heat storage material of the heat storage medium is a metal hydride or an amide.

[0019] Furthermore, the heat storage device is single-stage, two-stage, three-stage or multi-stage heat storage; the temperature inside the single-stage heat storage device is above 300 degrees.

[0020] Furthermore, the heat storage device has two-stage heat storage, the first stage is a high-temperature heat storage unit, and the temperature range of the heat storage medium is 500 degrees to 1200 degrees; the second stage is a low-temperature heat storage unit, and the temperature range of the heat storage medium is 300 degrees to 500 degrees.

[0021] A second aspect of the present invention provides a working method of a thermal power generation peak-shaving and frequency-regulating system of a thermal power plant, comprising the following steps:

[0022] S1. Design and select the best heat storage medium for the heat storage device according to the site conditions in the thermal power plant, and design the number of heat storage stages and the temperature range of the heat storage medium for each stage of heat storage device;

[0023] S2. According to the temperature of the heat storage medium of each stage of the heat storage device, the corresponding heat storage source is selected, and the peak-shaving and frequency-modulating electric heater driven by the peak-shaving and frequency-modulating electricity is used as the heat storage source, or the high-temperature flue gas, main steam, reheat steam or extraction steam of the boiler is used as the heat storage source;

[0024] S41. According to the current operation status of the thermal power plant, if there is surplus peak-shaving and frequency-regulating power to drive the peak-shaving and frequency-regulating electric heater, then jump to step S42; if the boiler allows the extraction of high-temperature flue gas for heating the heat storage medium, then jump to step S43; if the thermal power plant has surplus main steam, reheat steam or extraction steam for heating the heat storage medium, then jump to step S44;

[0025] S42, using the surplus peak-shaving and frequency-modulating electricity to supply power to the peak-shaving and frequency-modulating electric heater of the heat storage device, and using electric heating to make the heat storage medium reach its heat storage temperature;

[0026] S43, opening the heating flue gas inlet valve and outlet valve of the high-temperature flue gas heat exchanger, and the high-temperature flue gas from the boiler enters the high-temperature flue gas heat exchanger to release heat and then is discharged from the outlet valve back to the flue of the power station boiler; the heat storage medium in the heat storage device absorbs the heat of the high-temperature flue gas and reaches its heat storage temperature;

[0027] S44, opening the heating steam inlet valve and outlet valve of the high-temperature steam heat exchanger, and the high-temperature steam drawn from the main steam, reheated steam or large steam turbine extraction steam of the thermal power plant boiler enters the high-temperature steam heat exchanger to release heat, and then is discharged from the outlet valve back to the thermal power system of the thermal power plant; the heat storage medium in the heat storage device absorbs the heat of the high-temperature steam and reaches its heat storage temperature;

[0028] S5. The steam generated by heating with the heat storage device enters the large steam turbine or the small steam turbine with heat storage in the thermal power plant to drive the generator to increase the power generation, thereby increasing the peak capacity of the thermal power plant during the peak period of power demand and reducing the use of coal in its boiler.

[0029] The beneficial effects of the present invention are:

[0030] 1) In the thermal power plant heat storage power generation peak-shaving and frequency modulation system of the present invention, the heat storage device exchanges heat with the thermal power plant through an electric heater or a high-temperature heat exchanger, and utilizes peak-shaving and frequency modulation electricity or peak-shaving and frequency modulation flue gas and steam to achieve heat storage, saving energy. It can assist in heat supply and power generation during the peak heat consumption of the thermal power plant. Conversely, the excess heat energy of the thermal power plant can be stored in the heat storage medium and supplied to the thermal power plant during the peak heat consumption, thereby realizing heat storage peak-shaving and frequency modulation of the thermal power plant.

[0031] 2) The thermal storage power generation peak-shaving and frequency regulation system of the thermal power plant is set up in the thermal power plant, making full use of the existing thermal power unit equipment, without the need to build new generating units, thus saving huge investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a general schematic diagram of the thermal power generation peak-shaving and frequency-regulating system of a thermal power plant in Embodiment 1 of the present invention;

[0033] Figure 2 This is a general schematic diagram of the peak-shaving and frequency-regulating system for thermal power generation and heat storage in a thermal power plant in Embodiment 2 of the present invention;

[0034] Figure 3 This is a general schematic diagram of the thermal power generation peak-shaving and frequency-regulating system of a thermal power plant in Embodiment 3 of the present invention;

[0035] Figure 4 It is a schematic diagram of the operating steps of the working method of the thermal storage power generation peak-shaving and frequency modulation system of a thermal power plant in Example 4 of the present invention.

[0036] Reference numerals

[0037] 1- Power station boiler, 2- Large steam turbine, 3- Generator, 4- Condenser, 5- Low-pressure heater, 6- Deaerator, 7- High-pressure heater, 8- Low-pressure heat storage tank feed water pump, 9- Heat storage device, 10- Peak-shaving and frequency-regulating electric heater, 11- Small heat storage steam turbine, 12- Low-pressure heating superheat exchanger, 13- High-temperature flue gas heat exchanger, 14- High-temperature steam heat exchanger, 15- Unit peak-shaving and frequency-regulating control unit, 16- Small generator, 17- Molten salt cold tank, 18- Molten salt hot tank, 19- Solid heat storage magnesium brick, 20- High-temperature resistant fan. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0039] Example 1

[0040] like Figure 1 As shown, a thermal power plant heat storage power generation peak-shaving and frequency regulation system includes a heat storage device 9 and a unit peak-shaving and frequency regulation control unit 15. The thermal power plant heat storage power generation peak-shaving and frequency regulation system is arranged in a thermal power plant, and the thermal power plant includes a power plant boiler 1, a large steam turbine 2 and a generator 3. The power plant boiler 1 in the thermal power plant burns pulverized coal to heat the water in the boiler, generates water vapor, drives the large steam turbine 2 to move and generate kinetic energy, and the large steam turbine drives the generator 3 rotor to move, cuts the magnetic lines of force and generates electricity. The steam that releases the thermal potential energy is discharged from the exhaust port of the large steam turbine 2, sent to the condenser 4 for cooling, and condensed into water again. The condensed water is sent to the low-pressure heater 5 by the condensate pump and finally returns to the deaerator 6. The water in the deaerator 6 is sent to the heat storage device 9 through the low-pressure heat storage tank feed water pump 8. The low-pressure heating superheat exchanger in the heat storage device is connected to the reheater (not shown) and the small heat storage steam turbine 11 in the thermal power plant, the reheater is connected to the large steam turbine 2, and the small heat storage steam turbine 11 is connected to the small generator 16 and the condenser 4. The large steam turbine 2 and the generator 3 are existing units in the thermal power plant, and the small heat storage steam turbine 11 and the small generator 16 can be newly invested and constructed thermal power units, and the power generation capacity is smaller than the large steam turbine 2 and the generator 3 of the thermal power plant. The unit peak-shaving and frequency-regulating control unit 15 controls the charging of the heat storage device 9 according to the dispatching instructions of the power plant centralized control system of the upper power grid. When there is surplus power supply, the power plant centralized control system controls the unit peak-shaving and frequency-regulating control unit 15 to charge the heat storage device 9. The peak-shaving and frequency-regulating electric heater 10 uses the power supplied by the unit peak-shaving and frequency-regulating control unit 15 to heat the heat storage medium. The peak-shaving and frequency-modulating electric heater 10 arranged in the heat storage device is powered by the generator export bus, the plant power bus or the plant bus after the booster station, and the peak-shaving and frequency-modulating power of the thermal power plant is used to meet the power supply of the peak-shaving and frequency-modulating electric heater. The generator export bus is the generator terminal voltage bus, and the generator export bus is connected to the plant power bus through the reactor.

[0041] When the power supply is tight, the power plant centralized control system controls the unit peak-shaving and frequency-regulating control unit 15, and controls the heat storage device 9 to release heat for power generation. The low-pressure heater 5 in the thermal power plant is connected to the deaerator or condenser, and the feed water or condensate is sent to the low-pressure heating superheat exchanger 12 arranged in the heat storage device through the low-pressure heat storage tank feed water pump 8. The heat storage device releases heat energy to heat the water in the low-pressure heating superheat exchanger 10, and the generated superheated steam is sent to the thermal power unit reheater. After the steam temperature is further increased, it enters the medium-pressure cylinder of the large steam turbine 2 to generate power, or is sent to the small heat storage steam turbine 11 to generate power. The steam released from the small heat storage steam turbine 11 enters the condenser 4 for cooling.

[0042] The heat storage device 9 includes a heat storage medium, a peak-shaving and frequency-modulating electric heater 10, and a low-pressure heating superheat exchanger 12; the heat storage medium is any one of a sensible heat storage material, a latent heat storage material, and a thermochemical heat storage material. The sensible heat storage material includes any one of concrete, solid magnesium bricks, solid heat-resistant bricks, solid heat-resistant sand, and high-temperature heat-conducting oil. The latent heat storage material includes any one of high-temperature molten salts, mixed salts, metals, and alloys, and the high-temperature molten salt includes any one or a combination of alkali metals, alkaline earth metal halides, silicates, carbonates, nitrates, and phosphates. The thermochemical heat storage material is a metal hydride or an amide.

[0043] The heat storage device is single-stage, two-stage, three-stage or multi-stage heat storage; the temperature inside the single-stage heat storage device is above 300 degrees.

[0044] When the heat storage device is a two-stage heat storage device, the first stage is a high-temperature heat storage unit, and the temperature range of the heat storage medium is 500 degrees to 1200 degrees; the second stage is a low-temperature heat storage unit, and the temperature range of the heat storage medium is 300 degrees to 500 degrees.

[0045] A high-temperature flue gas heat exchanger 13 is also arranged in the heat storage device, which is connected to the flue gas supply and return pipeline of the power station boiler. The flue gas supply and return pipeline includes a flue gas supply pipeline and a flue gas return pipeline. An inlet valve is set on the flue gas supply pipeline, and an outlet valve is set on the flue gas return pipeline. When it is necessary to store heat for the solid heat storage brick, the inlet valve on the flue gas supply pipeline is opened, and the high-temperature flue gas of the power station boiler is extracted to heat the heat storage medium. After the heat storage medium in the heat storage device absorbs the heat of the high-temperature flue gas, it reaches its heat storage temperature. After the heat exchange is completed, the low-temperature flue gas is discharged from the outlet valve, returned to the power station boiler through the flue gas return pipeline, and discharged through the exhaust pipe of the power station boiler. When the heat storage device is needed to generate electricity, the heat storage device releases heat energy to heat the water in the low-pressure heating superheat heat exchanger 10, and the superheated steam generated is sent to the reheater of the thermal power unit. After the steam temperature is further increased, it enters the medium-pressure cylinder of the large steam turbine 2 to generate power, or is sent to the small heat storage steam turbine 11 to generate power.

[0046] A high-temperature steam heat exchanger 14 is also arranged in the heat storage device, which is connected to the high-temperature steam pipeline. The high-temperature steam pipeline is connected to the main steam pipeline of the pulverized coal boiler of the thermal power plant, the reheater pipeline and the steam extraction pipeline of the steam turbine through the inlet valve, and extracts any high-temperature steam from the main steam of the power station boiler, the reheated steam or the large steam turbine extraction steam. After the heat storage medium in the heat storage device absorbs the heat of the high-temperature steam, it reaches its heat storage temperature. The low-temperature steam after heat exchange is sent to the condenser 4 of the large steam turbine for cooling. When the heat storage device is needed to generate electricity, the heat storage device releases heat energy to heat the water in the low-pressure heating superheat exchanger 10, and the superheated steam generated is sent to the reheater of the thermal power unit. After the steam temperature is further increased, it enters the medium-pressure cylinder of the large steam turbine 2 to generate power, or is sent to the small heat storage steam turbine 11 to generate power.

[0047] The beneficial effects of this embodiment are:

[0048] 1) The heat storage device is used to exchange heat with the thermal power plant through an electric heater or a high-temperature heat exchanger, and the peak-shaving and frequency-regulating electricity or peak-shaving and frequency-regulating flue gas and steam are used to store heat and save energy. It can assist in heating and power generation during the peak heat consumption of the thermal power plant. Conversely, the excess heat energy of the thermal power plant can be stored in the heat storage medium and supplied to the thermal power plant during the peak heat consumption, thereby realizing the heat storage peak-shaving and frequency regulation of the thermal power plant.

[0049] 2) Utilize the steam turbines and generators in the existing thermal power unit equipment, without investing in new steam turbines and generator sets, thus saving huge investment.

[0050] Example 2

[0051] like Figure 2 As shown, the heat storage medium in the heat storage device in this embodiment is high-temperature molten salt, and the heat storage device also includes a molten salt cold tank 17 and a molten salt hot tank 18.

[0052] When it is necessary to store heat for the heat storage medium in the heat storage device, the cold salt in the molten salt cold tank 17 is pumped to the peak-shaving and frequency-modulating electric heater 10 through a molten salt pump, and the peak-shaving and frequency-modulating electric heater 10 is used for heating with the peak-shaving and frequency-modulating electricity, and the heated molten salt is pumped to the molten salt hot tank 18 through a hot salt pump; or the cold salt in the molten salt cold tank 17 is pumped to the high-temperature flue gas heat exchanger 13 through a molten salt pump, and the molten salt is heated with the high-temperature flue gas of the power station boiler, and the heated molten salt is pumped to the molten salt hot tank 18 through a hot salt pump; or the cold salt in the molten salt cold tank 17 is pumped to the high-temperature steam heat exchanger 14 through a molten salt pump, and the molten salt is heated with the main steam, reheated steam or large steam turbine extraction steam of the power station boiler, and the heated molten salt is pumped to the molten salt hot tank 18 through a hot salt pump.

[0053] When the heat storage medium in the heat storage device is needed to generate electricity, the high-temperature molten salt in the molten salt hot tank 18 is pumped into the low-pressure heating superheat heat exchanger 12 through the molten salt pump, and the high-temperature molten salt heats the water in the low-pressure heating superheat heat exchanger 12 to generate steam. The high-temperature steam enters the large steam turbine 2 to generate electricity, or enters the small heat storage steam turbine 11 to generate electricity.

[0054] The beneficial effect of this embodiment is that high-temperature molten salt is used as the heat storage medium, the heat storage device occupies a small area, and the high-temperature steam or high-temperature flue gas of the thermal power plant is utilized, the efficiency of the heat storage device can reach more than 70%, and the cost is relatively low.

[0055] Example 3

[0056] like Figure 3 As shown, the heat storage medium in the heat storage device 9 in this embodiment is a solid heat storage brick, and the heat storage material of the solid heat storage brick includes any one of concrete, solid magnesium brick, solid heat-resistant brick, solid heat-resistant sand, sand, and soil. Preferably, the solid heat storage brick in this embodiment is a solid heat storage magnesium brick. Solid heat storage magnesium bricks 19 are arranged in the heat storage device 9, and the peak-shaving and frequency-modulating electric power is used to drive the peak-shaving and frequency-modulating electric heater 10 to store heat in the solid magnesium brick. The peak-shaving and frequency-modulating electric heater 10 in the heat storage device 9 is an electric heating plate or electric heating wire arranged in the solid heat storage brick, and the peak-shaving and frequency-modulating electric heater 10 is connected to the peak-shaving and frequency-modulating control unit 15 of the unit in the power plant. When the heat storage device needs to release heat to generate electricity, the high-temperature resistant fan 20 draws air through the air duct to the solid heat storage magnesium bricks 19. The solid heat storage magnesium bricks 19 heat the air flowing through it. The heated air flows to the fin tubes of the low-pressure heating superheat exchanger 12, heats the liquid in the fin tubes, and then enters the high-temperature resistant fan 20 to continue circulating. The high-temperature steam generated by the heated liquid in the fin tubes enters the large steam turbine 2 to generate electricity, or enters the small heat storage steam turbine 11 to generate electricity.

[0057] Example 4

[0058] like Figure 4 As shown, the working method of the thermal storage power generation peak regulation and frequency regulation system of a thermal power plant includes the following steps:

[0059] S1. According to the site conditions in the thermal power plant, design and select the best heat storage medium for the heat storage device, and design the heat storage stages and the temperature range of the heat storage medium for each stage of the heat storage device; the heat storage medium is any one of sensible heat storage materials, latent heat storage materials, and thermochemical heat storage materials. Sensible heat storage materials include any one of concrete, solid magnesium bricks, solid heat-resistant bricks, solid heat-resistant sand, and high-temperature heat-resistant heat transfer oil. Latent heat storage materials include any one of high-temperature molten salts, mixed salts, metals and alloys, etc. High-temperature molten salts include any one or a combination of alkali metals, alkaline earth metal halides, silicates, carbonates, nitrates and phosphates. Thermochemical heat storage materials are metal hydrides or amides. According to the peak and frequency regulation capabilities of the thermal power plant, as well as the solid heat storage materials selected for the heat storage device and the heat storage temperature working range of the solid heat storage materials, design the heat storage stages of the heat storage device.

[0060] S2. According to the temperature of the heat storage medium of each stage of the heat storage device (9), a corresponding heat storage heat source is selected, and a peak-shaving and frequency-modulating electric heater (10) driven by peak-shaving and frequency-modulating electricity is used as the heat storage heat source, or high-temperature flue gas, main steam, reheat steam or extraction steam of the boiler is used as the heat storage heat source;

[0061] S41. According to the current operation status of the thermal power plant, if there is surplus peak-shaving and frequency-regulating power to drive the peak-shaving and frequency-regulating electric heater (10), then jump to step S42; if the boiler allows the extraction of high-temperature flue gas for heating the heat storage medium, then jump to step S43; if the thermal power plant has surplus main steam, reheat steam or extraction steam for heating the heat storage medium, then jump to step S44;

[0062] S42, using the surplus peak-shaving and frequency-modulating power to power the electric heater of the heat storage device, and using electric heating to make the heat storage medium reach its heat storage temperature;

[0063] S43, opening the inlet valve and outlet valve of the flue gas heat exchanger, the high-temperature flue gas from the boiler enters the high-temperature flue gas heat exchanger to release heat and then is discharged from the outlet valve back to the flue of the power station boiler; the heat storage medium in the heat storage device absorbs the heat of the high-temperature flue gas and reaches its heat storage temperature;

[0064] S44, opening the heating steam inlet valve and outlet valve of the high-temperature steam heat exchanger, and the high-temperature steam drawn from the main steam, reheated steam or large steam turbine extraction steam of the thermal power plant boiler enters the high-temperature steam heat exchanger to release heat, and then is discharged from the outlet valve back to the thermal power system of the thermal power plant; the heat storage medium in the heat storage device absorbs the heat of the high-temperature steam and reaches its heat storage temperature;

[0065] S5. The steam generated by heating with the heat storage device enters the large steam turbine or the small steam turbine with heat storage in the thermal power plant to drive the generator to increase the power generation, thereby increasing the peak capacity of the thermal power plant during the peak period of power demand and reducing the use of coal in its boiler.

[0066] The beneficial advantage of this embodiment is that it can perform peak-shaving and frequency regulation according to the surplus power of the thermal power plant, the high-temperature steam or high-temperature flue gas of the thermal power plant. Even in summer, the high-temperature steam or high-temperature flue gas of the thermal power plant can be used to store heat in the heat storage device, and the heat energy can be converted into electrical energy through the heat storage device, participating in the peak-shaving and frequency regulation of the thermal power plant to ensure power supply.

[0067] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present invention.

Claims

1. A thermal power plant thermal storage power generation peak load regulation and frequency modulation system, arranged in a thermal power plant, the thermal power plant comprising a power plant boiler (1), a large steam turbine (2) and a generator (3), characterized in that: The thermal power plant heat storage power generation peak-shaving and frequency regulation system comprises a heat storage device (9) and a unit peak-shaving and frequency regulation control unit (15); The heat storage device (9) comprises a heat storage medium, a peak-shaving and frequency-modulating electric heater (10), and a low-pressure heating superheat exchanger (12); The heat storage medium is any one of a sensible heat storage material, a latent heat storage material, and a thermochemical heat storage material; The peak-shaving and frequency-modulating electric heater (10) utilizes the surplus power of the thermal power unit for peak-shaving and frequency-modulating to heat the heat storage medium or utilizes the high-temperature flue gas or high-temperature steam in the thermal power plant to heat the heat storage medium; The superheated steam generated by the low-pressure heating superheat exchanger (12) arranged in the heat storage device (9) is sent to the reheater of the thermal power unit and then enters the large steam turbine (2) to drive the generator (3), or the superheated steam enters the small heat storage steam turbine (11) to drive the small generator (16) to generate electricity; A high-temperature flue gas heat exchanger (13) is also arranged in the heat storage device (9), connected to the flue gas supply and return pipeline of the power station boiler, and extracts the high-temperature flue gas of the power station boiler to heat the heat storage medium; A high-temperature steam heat exchanger (14) is also arranged in the heat storage device (9) and connected to a high-temperature steam pipeline, wherein the high-temperature steam comes from any one of the main steam of the power station boiler, the reheated steam or the steam extracted from a large steam turbine; When there is surplus power supply, the power plant centralized control system controls the unit peak load and frequency regulation control unit (15) to charge the heat storage device (9); When the power supply is tight, the power plant centralized control system controls the unit peak load and frequency regulation control unit (15) to control the heat storage device (9) to release heat and generate electricity.

2. The thermal power plant thermal storage power generation peak load regulation and frequency modulation system according to claim 1, characterized in that: The power supply of the peak-shaving and frequency-modulating electric heater (10) comes from the generator outlet bus, the plant power bus or the post-boosting station exit bus, and the peak-shaving and frequency-modulating power of the thermal power plant is used to meet the power supply of the peak-shaving and frequency-modulating electric heater (10).

3. The thermal power generation peak-shaving and frequency modulation system of thermal power plant according to claim 1, characterized in that: The low-pressure heater (5) in the thermal power plant is connected to the deaerator (6) or the condenser (4), and the feed water or condensed water is sent to the low-pressure heating superheat exchanger (12) arranged in the heat storage device (9) through the low-pressure feed water pump (8).

4. The thermal power plant thermal storage power generation peak load regulation and frequency modulation system according to claim 1, characterized in that: The sensible heat storage material of the heat storage medium includes any one of concrete, solid magnesium brick, solid heat-resistant brick, solid heat-resistant sand, and high-temperature resistant heat-conducting oil.

5. The thermal power plant thermal storage power generation peak load regulation and frequency modulation system according to claim 1, characterized in that: The latent heat storage material of the heat storage medium includes any one of high-temperature molten salt, mixed salts, metals and alloys, and the high-temperature molten salt formula includes any one or a combination of alkali metals, alkaline earth metal halides, silicates, carbonates, nitrates and phosphates.

6. The thermal power generation peak-shaving and frequency modulation system of thermal power plant according to claim 1, characterized in that: The thermochemical heat storage material of the heat storage medium is a metal hydride or an amide.

7. The thermal power generation peak-shaving and frequency modulation system of thermal power plant according to claim 1, characterized in that: The heat storage device (9) is a single-stage, two-stage, three-stage or multi-stage heat storage device; the temperature inside the single-stage heat storage device is above 300 degrees.

8. The thermal power plant thermal storage power generation peak load regulation and frequency modulation system according to claim 7, characterized in that: The heat storage device (9) has two stages of heat storage, the first stage is a high-temperature heat storage unit, the temperature range of the heat storage medium is 500 to 1200 degrees; the second stage is a low-temperature heat storage unit, the temperature range of the heat storage medium is 300 to 500 degrees.

9. A working method of the thermal power plant thermal storage power generation peak-shaving and frequency modulation system according to any one of claims 1 to 8, characterized in that: The steps include: S1. Design and select the best heat storage medium for the heat storage device (9) according to the site conditions in the thermal power plant, and design the number of heat storage stages and the temperature range of the heat storage medium for each stage of the heat storage device; S2. According to the temperature of the heat storage medium of each stage of the heat storage device (9), a corresponding heat storage heat source is selected, and a peak-shaving and frequency-modulating electric heater (10) driven by peak-shaving and frequency-modulating electricity is used as the heat storage heat source, or high-temperature flue gas, main steam, reheat steam or extraction steam of the boiler is used as the heat storage heat source; S41. According to the current operation status of the thermal power plant, if there is surplus peak-shaving and frequency-regulating power to drive the peak-shaving and frequency-regulating electric heater (10), then jump to step S42; if the boiler allows the extraction of high-temperature flue gas for heating the heat storage medium, then jump to step S43; If the thermal power plant has surplus main steam, reheat steam or extraction steam for heating the thermal storage medium, the process jumps to step S44; S42, using the surplus peak-shaving and frequency-modulating electric power to supply power to the peak-shaving and frequency-modulating electric heater (10) of the heat storage device (9), and using electric heating to make the heat storage medium reach its heat storage temperature; S43, opening the hot flue gas inlet valve and outlet valve of the high-temperature flue gas heat exchanger (13), allowing the hot flue gas drawn from the boiler to enter the high-temperature flue gas heat exchanger (13) and release heat before being discharged from the outlet valve back to the flue of the power station boiler; the heat storage medium in the heat storage device (9) absorbs the heat of the high-temperature flue gas and reaches its heat storage temperature; S44, opening the heating steam inlet valve and outlet valve of the high-temperature steam heat exchanger (14), allowing the high-temperature steam drawn from the main steam, reheated steam or steam extraction of the large steam turbine (2) of the thermal power plant boiler to enter the high-temperature steam heat exchanger (14), release heat, and then be discharged from the outlet valve back to the thermal power plant thermal system; the heat storage medium in the heat storage device (9) absorbs the heat of the high-temperature steam and reaches its heat storage temperature; S5. The steam generated by heating with the heat storage device (9) enters the large steam turbine or the small steam turbine (11) of the thermal power plant to drive the generator to increase the power generation, thereby increasing the peak capacity of the thermal power plant during the peak period of power demand and reducing the use of coal in its boiler.

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