System applied to thermal power flexibility transformation and steam supply

Abstract

A system applied to thermal power flexibility transformation and steam supply comprises a steam turbine unit, a compressor unit and an energy storage system. The steam turbine set comprises a boiler and a steam turbine, and the steam turbine is connected with and drives a power generator to generate power; the number of the compressor units is one or more, each compressor unit comprises a motor and a compressor, and after low-pressure saturated steam output by the steam turbine enters the compressors, the low-pressure saturated steam is pressurized and heated to generate high-temperature and high-pressure steam; the energy storage system comprises a high-temperature storage tank and a low-temperature storage tank and is used for storing heat energy in high-temperature and high-pressure steam generated by the compressor. The system has the advantages of being high in heating efficiency, simple in system operation, high in system flexibility and safe.

Description

Technical Field

[0001] This invention relates to the field of energy technology, and in particular to a system for the flexible retrofitting and steam supply of thermal power plants. Background Technology

[0002] In recent years, the photovoltaic and wind power sectors have developed rapidly. However, the variable weather conditions have also had a significant impact on the stability of the power grid. Therefore, it is necessary to modify thermal power units as baseload power sources to improve their flexibility. Actively reducing load during periods of high photovoltaic and wind power generation is currently the most effective means of stabilizing grid fluctuations. Current methods for improving the flexibility of thermal power units include turbine bypass modification, low-load boiler combustion stabilization technology, high-temperature heat pump molten salt energy storage technology, and electric heating molten salt energy storage technology. However, each has its own drawbacks. For example, turbine bypass modification and boiler combustion stabilization technology cannot reduce the power generation of thermal power units to zero for grid connection. The electro-electric conversion efficiency of electric heating molten salt energy storage technology is less than 50%, while the electro-electric conversion efficiency of high-temperature heat pump molten salt energy storage technology is slightly higher at about 60%. However, the system operation is complex, the initial investment in equipment is high, and it requires modification of the main steam pipeline, affecting the operational safety of the power plant itself.

[0003] Steam is the "lifeblood" of industry, widely used in various sub-sectors of manufacturing, including petroleum, chemical, power, machinery, textile, metallurgy, food, and pharmaceutical industries. Currently, most steam supply relies on coal-to-gas conversion. However, due to the continuous rise in coal prices and the difficulty in obtaining additional coal quotas in recent years, many electric steam generation technologies have emerged, such as high-temperature heat pump technology and heat pump steam turbine technology. However, each has its own drawbacks, such as the low COP of high-temperature heat pump technology and the inability of heat pump steam turbine technology to store energy. Therefore, the industry urgently needs a new system that can both provide flexible peak-shaving for thermal power and supply industrial steam. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a system for the flexible retrofitting of thermal power plants and steam supply, which has the advantages of high heating efficiency, simple system operation, high system flexibility, and safety.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A system for the flexible retrofitting and steam supply of thermal power plants, characterized in that it includes a steam turbine unit, a compressor unit, and an energy storage system;

[0007] Steam turbine unit: includes a boiler and a steam turbine, the steam turbine being connected to and driving a generator to generate electricity;

[0008] Compressor unit: The compressor unit is provided in one or more sets, each compressor unit includes an electric motor and a compressor. The low-pressure saturated steam output by the steam turbine enters the compressor and is pressurized and heated to produce high-temperature and high-pressure steam.

[0009] Energy storage system: including high-temperature storage tanks and low-temperature storage tanks, used to store the thermal energy in the high-temperature and high-pressure steam generated by the compressor.

[0010] Furthermore, when the compressor unit is configured as a group, the compressor is also connected to a first heat exchanger, and the high-temperature and high-pressure steam after heat exchange is incorporated into the industrial steam supply network. The first heat exchanger is connected to a high-temperature storage tank and a low-temperature storage tank.

[0011] Furthermore, when the compressor unit is configured as multiple units, the multiple compressor units are connected in series to form a multi-stage compressor unit. Each compressor unit is connected to a first heat exchanger. The high-temperature and high-pressure steam after heat exchange is incorporated into the industrial steam supply network. Several of the first heat exchangers are simultaneously connected to high-temperature storage tanks and low-temperature storage tanks.

[0012] Furthermore, when the compressor unit is configured as multiple units, the multiple compressor units are connected in parallel, each compressor unit is connected to a first heat exchanger or all compressor units are connected to the same first heat exchanger, and the high-temperature and high-pressure steam after heat exchange is fed into the industrial steam supply network, and the first heat exchanger is connected to a high-temperature storage tank and a low-temperature storage tank.

[0013] Furthermore, the high-temperature storage tank and the low-temperature storage tank are also connected to a second heat exchanger. After the second heat exchanger is supplied with water, it generates high-temperature and high-pressure steam, which is then fed into the industrial steam supply network.

[0014] Furthermore, the high-temperature storage tank and the low-temperature storage tank are also connected to a second heat exchanger. After the second heat exchanger is fed with water, it generates high-temperature and high-pressure steam, which is then further pressurized and heated before being incorporated into the steam pipeline from the boiler to the steam turbine.

[0015] Furthermore, the turbine unit also includes a condenser and a feedwater pump. The condenser is connected to the turbine and converts the low-temperature, low-pressure steam output from the turbine into liquid water, which is then fed into the boiler along with the feedwater pump.

[0016] Furthermore, the high-temperature storage tank and the low-temperature storage tank are molten salt storage tanks.

[0017] The present invention has the following beneficial effects:

[0018] 1. This invention proposes a system with a wider range of applications and richer functions, which can be used for flexible peak shaving of thermal power plants as well as for industrial steam supply.

[0019] 2. The system provided by this invention significantly improves heating efficiency and economic efficiency. Furthermore, the addition of a molten salt energy storage device as a flexible energy source reduces the difficulty for the compressor to adapt to different loads.

[0020] 3. The system provided by this invention has a simple structure and operation, low equipment investment cost, and does not require modification of the main steam pipeline of the thermal power plant, making it safer and having good practical feasibility. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of Embodiment 1 of the present invention;

[0022] Figure 2 This is a schematic diagram of Embodiment 2 of the present invention;

[0023] Figure 3 This is a schematic diagram of Embodiment 3 of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Example 1:

[0026] A system for the flexible retrofitting and steam supply of thermal power plants includes a steam turbine unit, a compressor unit, and an energy storage system. The steam turbine unit comprises a boiler and a steam turbine. The high-temperature, high-pressure gas generated by the boiler drives the steam turbine, which is connected to a generator and drives the generator to produce electricity. Simultaneously, the steam turbine is also connected to a condenser. After the high-temperature, high-pressure steam in the thermal power plant expands and performs work in the steam turbine, the resulting low-pressure saturated steam, carrying a large amount of latent heat, enters the condenser, where it is converted into liquid water. This liquid water is then pumped into the power plant's feedwater pump and finally into the boiler.

[0027] The compressor unit includes an electric motor and a compressor. In this embodiment, multiple compressor units are provided, forming a multi-stage compressor unit. For example... Figure 1 As shown, the compressor unit consists of three sets: motor A and compressor A, motor B and compressor B, and motor C and compressor C. The compressor units are connected in series, that is, compressor A, compressor B and compressor C are connected in sequence. The low-pressure saturated steam discharged from the steam turbine is first introduced into compressor A.

[0028] Each compressor is connected to a corresponding first heat exchanger. Steam is heated and pressurized inside the compressor to form high-temperature, high-pressure steam, which then undergoes heat exchange in the first heat exchanger. Each first heat exchanger is connected to an energy storage system, which includes a high-temperature storage tank and a low-temperature storage tank. In this embodiment, the high-temperature and low-temperature storage tanks are molten salt storage tanks, i.e., hot salt tanks and cold salt tanks, used to store the thermal energy in the high-temperature, high-pressure steam generated by the compressor.

[0029] In this embodiment, the first heat exchanger includes heat exchanger A, heat exchanger B, and heat exchanger C. Specifically, compressor A is connected to heat exchanger A, heat exchanger A is connected to compressor B, compressor B is connected to heat exchanger B, heat exchanger B is connected to compressor C, and compressor C is connected to heat exchanger C. Furthermore, heat exchangers A, B, and C are all connected to a hot salt tank and a cold salt tank.

[0030] The hot and cold salt tanks are also connected to a second heat exchanger, which in this embodiment is heat exchanger D. Water is supplied to heat exchanger D. At this time, the energy storage system stores a large amount of thermal energy. The hot and cold salt tanks provide heat to heat the water into high-temperature and high-pressure steam, which is then fed into the industrial steam supply network. Alternatively, it can be combined with the high-temperature and high-pressure steam generated in the boiler and then fed into the steam turbine to drive power generation.

[0031] The operating principle of this embodiment is as follows: After the high-temperature and high-pressure steam generated in the boiler of the thermal power plant expands and does work in the steam turbine to drive the generator to generate electricity, the low-pressure saturated steam with a large amount of latent heat first enters the compressor A for pressurization and heating, and then enters the heat exchanger A for heat exchange, transferring the heat energy in the high-temperature and high-pressure steam to the molten salt in the energy storage device for heat energy storage; the high-temperature and high-pressure steam after heat exchange continues to enter the compressor B, and after pressurization and heating, it enters the heat exchanger B for heat exchange, transferring the heat energy to the molten salt for storage; the high-temperature and high-pressure steam after heat exchange continues to enter the compressor C, and after pressurization and heating, it enters the heat exchanger C for heat exchange, transferring the heat energy to the molten salt for storage; the high-temperature and high-pressure steam after heat exchange is connected to the industrial steam supply network for industrial steam supply. After heat exchange through heat exchangers A, B, and C, a large amount of thermal energy is stored in the energy storage system. At this time, water is supplied at heat exchanger D, and the hot and cold salt tanks are heated to form high-temperature and high-pressure steam for use in the industrial steam supply network, or it is combined with the high-temperature and high-pressure steam generated in the boiler and then fed into the steam turbine to drive power generation.

[0032] In addition, the number of stages of the compressor unit can be adjusted according to actual needs, and the number of the first heat exchangers can also be changed accordingly based on the adjustment of the number of compressor units.

[0033] With the above setup, a large amount of thermal energy can be stored in the energy storage system. This portion of heat becomes a flexible energy source, which can be released to help the thermal power plant generate electricity or provide additional steam when peak demand for thermal power plants or when industrial steam needs to be supplied in large quantities.

[0034] The heating COP of this process can be greater than 2.5 (when the high-temperature and high-pressure steam parameters are 0.8 MPa and 200℃), which greatly improves heating efficiency and economics compared to high-temperature heat pump technology (COP < 1.5). This is because the exhaust steam from the turbine contains a large amount of latent heat. This energy would normally need to enter the condenser to remove the heat, thus turning the low-temperature, low-pressure steam into liquid water for the power plant's feedwater pump, but this process would result in a significant waste of energy. By omitting this condensation and cooling process and directly passing the turbine exhaust steam into the compressor for pressurization and heating, this large amount of latent heat can be utilized directly. Therefore, the heating COP of this system is high. Furthermore, the addition of molten salt energy storage as a flexible energy source reduces the design complexity of the compressor to adapt to different loads. In addition, this system is simple to operate, has low equipment investment costs, and does not require modification of the main steam pipeline of the power plant, making it highly feasible in practice.

[0035] Example 2:

[0036] The difference between Example 2 and Example 1 is that, as Figure 2 As shown, in Example 2, the compressor units are divided into three groups, and the three compressor units are connected in parallel. Each compressor unit includes motor A and compressor A, motor B and compressor B, and motor C and compressor C. Compressor A is connected to heat exchanger A, which is not connected to compressor B, and is connected to both the hot and cold salt tanks. Compressor B is connected to heat exchanger B, which is not connected to compressor C, and is connected to both the hot and cold salt tanks. Compressor C is connected to heat exchanger C, which is connected to both the hot and cold salt tanks.

[0037] The operating principle of this embodiment is as follows: After the high-temperature and high-pressure steam generated in the boiler in the thermal power plant expands and does work through the steam turbine to drive the generator to generate electricity, the low-pressure saturated steam with a large amount of latent heat simultaneously enters compressor A, compressor B and compressor C respectively. After being pressurized and heated by the compressor, the heat is transferred to the molten salt for storage through heat exchangers A, B and C respectively. The steam after heat exchange is incorporated into the industrial steam supply network for industrial steam supply.

[0038] After heat exchange through heat exchangers A, B, and C, a large amount of thermal energy is stored in the energy storage system. At this time, water is supplied at heat exchanger D, and the hot and cold salt tanks are heated to form high-temperature and high-pressure steam for use in the industrial steam supply network, or it is combined with the high-temperature and high-pressure steam generated in the boiler and then fed into the steam turbine to drive power generation.

[0039] In addition, the number of stages of the compressor unit can be adjusted according to actual needs, and the number of the first heat exchangers can also be changed accordingly based on the adjustment of the number of compressor units.

[0040] Example 3:

[0041] The difference between Example 3 and Example 1 is that, as Figure 3 As shown, in Example 3, only one compressor unit is configured. The compressor unit includes an electric motor A and a compressor A. The compressor A is connected to a heat exchanger A, which is connected to a hot salt tank and a cold salt tank.

[0042] After heat exchange through heat exchanger A, a large amount of thermal energy is stored in the energy storage system. At this time, water is supplied at heat exchanger D, and the hot and cold salt tanks are heated to form high-temperature and high-pressure steam for use in the industrial steam supply network, or it is combined with the high-temperature and high-pressure steam generated in the boiler and then fed into the steam turbine to drive power generation.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A system for the flexible retrofitting and steam supply of thermal power plants, characterized in that: This includes steam turbine units, compressor units, and energy storage systems; Steam turbine unit: includes a boiler and a steam turbine, the steam turbine being connected to and driving a generator to generate electricity; Compressor unit: The compressor unit is provided in one or more sets, each compressor unit includes an electric motor and a compressor. The low-pressure saturated steam output by the steam turbine enters the compressor and is pressurized and heated to produce high-temperature and high-pressure steam. Energy storage system: including high-temperature storage tanks and low-temperature storage tanks, used to store the thermal energy in the high-temperature and high-pressure steam generated by the compressor.

2. The system for the flexible retrofitting and steam supply of thermal power plants according to claim 1, characterized in that: When the compressor unit is configured as a set, the compressor is also connected to a first heat exchanger. The high-temperature and high-pressure steam after heat exchange is fed into the industrial steam supply network. The first heat exchanger is connected to a high-temperature storage tank and a low-temperature storage tank.

3. A system for the flexible retrofitting and steam supply of thermal power plants according to claim 1, characterized in that: When the compressor unit is configured as multiple units, the multiple compressor units are connected in series to form a multi-stage compressor unit. Each compressor unit is connected to a first heat exchanger. The high-temperature and high-pressure steam after heat exchange is fed into the industrial steam supply network. Several first heat exchangers are simultaneously connected to high-temperature storage tanks and low-temperature storage tanks.

4. A system for the flexible retrofitting and steam supply of thermal power plants according to claim 1, characterized in that: When the compressor unit is configured as multiple units, the multiple compressor units are connected in parallel. Each compressor unit is connected to a first heat exchanger, or all compressor units are connected to the same first heat exchanger. The high-temperature and high-pressure steam after heat exchange is fed into the industrial steam supply network. The first heat exchanger is connected to a high-temperature storage tank and a low-temperature storage tank.

5. A system for the flexible retrofitting and steam supply of thermal power plants according to claims 2-4, characterized in that: The high-temperature storage tank and the low-temperature storage tank are also connected to a second heat exchanger. After water is supplied to the second heat exchanger, high-temperature and high-pressure steam is generated and fed into the industrial steam supply network.

6. A system for the flexible retrofitting and steam supply of thermal power plants according to claims 2-4, characterized in that: The high-temperature storage tank and the low-temperature storage tank are also connected to a second heat exchanger. After the second heat exchanger is fed with water, it generates high-temperature and high-pressure steam, which is then further pressurized and heated before being incorporated into the steam pipeline from the boiler to the steam turbine.

7. A system for the flexible retrofitting and steam supply of thermal power plants according to claim 1, characterized in that: The turbine unit also includes a condenser and a feedwater pump. The condenser is connected to the turbine and converts the low-temperature, low-pressure steam output from the turbine into liquid water, which is then fed into the boiler along with the feedwater pump.

8. A system for the flexible retrofitting and steam supply of thermal power plants according to claim 1, characterized in that: The high-temperature storage tank and the low-temperature storage tank are molten salt storage tanks.

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