A multi-mode power generation system for new energy large base and an operation method thereof

Abstract

The application relates to the technical field of power generation system peak regulation, in particular to a multi-mode power generation system for a new energy large base and a running method thereof. The multi-mode power generation system comprises a thermal power station and a molten salt energy storage power station; the thermal power station comprises a boiler, a first steam turbine, a first backwater unit and a first generator; the molten salt energy storage power station comprises a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heating unit, a steam-water heating unit, a second backwater unit, a second steam turbine and a second generator; an air inlet of the molten salt heating unit is configured to obtain steam flowing out of the boiler, and a second discharge port of the molten salt heating unit is connected with the first backwater unit; air outlets of the steam-water heating unit are respectively connected with the first steam turbine and the second steam turbine, and the first backwater unit and the second backwater unit are respectively connected with second feeding ports of the steam-water heating unit. The multi-mode power generation system can set different running modes according to different requirements, so that the new energy large base can meet higher requirements.

Description

Technical Field

[0001] This application relates to the field of peak shaving technology for power generation systems, and in particular to a multi-mode power generation system for large-scale new energy bases and its operation method. Background Technology

[0002] Large-scale new energy bases refer to large-scale energy bases that simultaneously construct, connect to the grid, jointly dispatch, and bundle power sources such as wind power, photovoltaics, thermal power, and energy storage facilities. The large-scale construction of new energy bases in deserts, Gobi, and other arid regions can not only effectively utilize local wind, solar, and land resources, but also effectively cover the desert surface through the installation of photovoltaic panels, reducing groundwater evaporation. Simultaneously, technologies such as under-panel planting and drip irrigation can be used to improve land use in desert and Gobi areas, ultimately achieving ecological improvement while utilizing energy.

[0003] Currently, large-scale new energy bases include both new energy power plants and thermal power plants. The thermal power plants are configured for flexible operation, and there is a coupling between the new energy power plants and the thermal power plants. When new energy resources such as wind and solar energy are abundant, the load on the thermal power plants is reduced; when new energy resources are insufficient, the load on the thermal power plants is increased. The output of the large-scale new energy bases is thus regulated using thermal power plants.

[0004] With the continuous adjustment of the energy structure, large-scale new energy bases are facing higher requirements. Specifically, when new energy resources are abundant, the load of thermal power plants needs to be further reduced; during peak electricity consumption periods, the output of large-scale new energy bases needs to be further increased; and the rate of change of load on thermal power plants needs to be further accelerated. Therefore, it is urgent to adjust the existing power generation system to meet these requirements. Summary of the Invention

[0005] Based on this, this application provides a multi-mode power generation system and its operation method for large-scale new energy bases, in order to address the shortcomings of large-scale new energy bases in meeting higher requirements.

[0006] On the one hand, this application provides a multi-mode power generation system for large-scale new energy bases, including thermal power plants and molten salt energy storage power plants;

[0007] The thermal power plant includes a boiler, a first steam turbine, a first return water unit, and a first generator. The boiler's outlet is connected to the first steam turbine's inlet. The first return water unit is connected between the first steam turbine and the boiler. The first generator is connected to the first steam turbine.

[0008] The molten salt energy storage power station includes a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heating unit, a steam-water heating unit, a second return water unit, a second steam turbine, and a second generator. The outlet of the low-temperature molten salt tank is connected to the inlet of the molten salt heating unit. The first outlet of the molten salt heating unit is connected to the inlet of the high-temperature molten salt tank. The outlet of the high-temperature molten salt tank is connected to the first inlet of the steam-water heating unit. The outlet of the steam-water heating unit is connected to the inlet of the low-temperature molten salt tank.

[0009] The air inlet of the molten salt heating unit is configured to obtain steam flowing out of the boiler, and the second outlet of the molten salt heating unit is connected to the first return water unit; the air outlet of the steam-water heating unit is connected to the first steam turbine and the second steam turbine respectively, the outlet of the second steam turbine is connected to the second return water unit, the second generator is connected to the second steam turbine, and the first return water unit and the second return water unit are connected to the second inlet of the steam-water heating unit respectively.

[0010] In one possible implementation, the molten salt energy storage power station also includes an electric heater, the inlet of which is connected to the first outlet of the molten salt heating unit, the outlet of which is connected to the inlet of the high-temperature molten salt tank, and the electric heater is electrically connected to the new energy power station.

[0011] In one possible implementation, the outlet of the steam heating unit is also connected to the first return water unit.

[0012] In one possible implementation, the steam-water heating unit includes multiple steam heating devices connected in sequence, and the second return water unit includes a peak condenser, multiple low-pressure heaters, a deaerator, and multiple high-pressure heaters. The peak condenser is connected to the second steam turbine, the multiple low-pressure heaters are connected in sequence between the peak condenser and the deaerator, and the multiple high-pressure heaters are connected between the deaerator and the steam-water heating unit.

[0013] In one possible implementation, the air inlets of each low-pressure heater, the air inlet of the deaerator, and the air inlet of each high-pressure heater are respectively connected to the air outlets of each steam heating device, and the drain outlets of each low-pressure heater and each high-pressure heater are respectively connected to the peak condenser.

[0014] In one possible implementation, on / off valves are installed on the pipelines between each low-pressure heater and the corresponding steam heating device, the pipelines between the deaerator and the corresponding steam heating device, and the pipelines between each high-pressure heater and the corresponding steam heating device.

[0015] In one possible implementation, valves are installed on the pipelines between the boiler and the first steam turbine, the pipelines between the boiler and the molten salt heating unit, and the pipelines between the molten salt heating unit and the first return water unit.

[0016] In one possible implementation, valves are installed on the pipelines between the steam-water heating unit and the first steam turbine, the pipelines between the steam-water heating unit and the second steam turbine, the pipelines between the first return water unit and the steam-water heating unit, and the pipelines between the second return water unit and the steam-water heating unit.

[0017] On the other hand, this application provides an operating method applied to the aforementioned multi-mode power generation system, wherein the multi-mode power generation system is coupled with a new energy power plant, and the operating method includes:

[0018] When the thermal power plant is in the first state, and the total load of the thermal power plant and the new energy power plant is greater than the power transmission load: adjust the boiler operating load to reduce it to the minimum stable combustion load, control the steam generated by the boiler to enter the molten salt heating unit, and control the steam flowing out of the molten salt heating unit to flow back to the first return water unit.

[0019] When the thermal power plant is in its first state, and the sum of the load of the thermal power plant and the load of the new energy power plant is less than the power transmission load: increase the operating load of the boiler, control the steam generated by the boiler to enter the first steam turbine, control part of the steam and water from the first return water unit to enter the steam and water heating unit, and control the steam flowing out of the steam and water heating unit to enter the first steam turbine.

[0020] When the thermal power plant is in the second state, and the total load of the thermal power plant and the load of the new energy power plant is less than the power transmission load: control the steam generated by the boiler to enter the first steam turbine, control part of the steam and water from the first return water unit to enter the steam and water heating unit, and control the steam flowing out of the steam and water heating unit to enter the second steam turbine.

[0021] The first state is when the boiler reaches its minimum stable combustion load, and the boiler drives the first steam turbine to drive the first generator to generate electricity; the second state is when the boiler reaches its maximum load, and the boiler drives the first steam turbine to drive the first generator to generate electricity.

[0022] In one possible implementation, when the load of the new energy power plant is greater than the power transmission load, the excess electricity generated by the new energy power plant is controlled to drive the electric heater to heat the molten salt flowing out of the molten salt heating unit.

[0023] This application provides a multi-mode power generation system and its operation method for large-scale new energy bases. When new energy resources are abundant, the boiler's operating load can be reduced to the minimum stable combustion load. The steam generated by the boiler can flow to the molten salt heating unit to heat the molten salt. At this time, the molten salt energy storage power station is in energy storage mode, and the load of the thermal power plant can be further reduced, increasing the proportion of new energy power generation output. When new energy resources are insufficient, part of the steam and water from the first return water unit can be heated into steam by the steam-water heating unit. The steam flowing out of the steam-water heating unit can flow together with the steam generated by the boiler to the first turbine, increasing the load change rate of the thermal power plant. During peak electricity consumption periods, the steam generated by the boiler flows to the first turbine, and the steam generated by the steam-water heating unit flows to the second turbine, enabling the first and second generators to generate electricity simultaneously. At this time, the power generation system is in peak power generation mode, ensuring that the output of the power generation system meets the electricity demand. In this way, large-scale new energy bases using multi-mode power generation systems can meet higher requirements. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram illustrating the power output of a large-scale power base in related technologies;

[0026] Figure 2 A schematic diagram of a multi-mode power generation system provided in an embodiment of this application;

[0027] Figure 3 A schematic diagram of a thermal power plant provided for an embodiment of this application;

[0028] Figure 4 A schematic diagram of a molten salt energy storage power station provided in an embodiment of this application;

[0029] Figure 5 This is a schematic diagram of the power output of a large-scale power source provided in an embodiment of this application;

[0030] Figure 6 The power output diagram of the molten salt energy storage power station provided in the embodiments of this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] 100 - Thermal power plant; 110 - Boiler; 120 - First steam turbine; 130 - First return water unit; 131 - Condenser; 132 - Low-pressure heating device; 133 - Deaerator; 134 - High-pressure heating device; 140 - First generator;

[0033] 200 - Molten salt energy storage power station; 210 - High-temperature molten salt tank; 220 - Low-temperature molten salt tank; 230 - Molten salt heating unit; 240 - Steam-water heating unit; 241 - Steam heating device; 250 - Second return water unit; 251 - Peak condenser; 252 - Low-pressure heater; 253 - Deaerator; 254 - High-pressure heater; 260 - Second steam turbine; 270 - Second generator; 280 - Electric heater;

[0034] 310 - On / off valve; 320 - Valve;

[0035] 400-New Energy Power Station. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0037] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0038] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0039] The terms “first,” “second,” and “third” (if any) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0040] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or display that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or display.

[0041] In existing technologies, large-scale new energy bases include new energy power plants and thermal power plants. The thermal power plants are configured for flexible scheduling, and the new energy power plants and thermal power plants are coupled. When new energy resources such as wind and solar energy are abundant, the load on the thermal power plants is reduced; when new energy resources are insufficient, the load on the thermal power plants is increased. The output of the large-scale new energy base is regulated using the thermal power plants. However, thermal power plants cannot operate at ultra-low loads. The minimum stable combustion load of boilers in thermal power plants is generally 30% of their rated capacity. For example, for a 1000MW rated thermal power plant, the minimum load cannot be lower than 300MW. When the boiler load falls below the minimum stable combustion load, boilers are prone to flameout and shutdown accidents. Figure 1 As shown, when renewable energy resources are abundant, the load of thermal power plants cannot be further reduced, leading to the curtailment of renewable energy. The rate of change of load in thermal power plants cannot be further adjusted, making it difficult to match the changes in renewable energy. The boiler load of thermal power plants can be adjusted by controlling coal feed, water feed, and air distribution, but the adjustment rate is mostly 1%-1.5%Pe / minute. That is, for a 1000MW thermal power plant, the load change rate is about 10-15MW / minute. If the coal feed, air distribution, and water feed of the boiler are forcibly increased, it is easy to cause serious accidents such as local overheating of the boiler and water-cooled wall rupture. Figure 1 The data shows that during peak electricity consumption periods, the output of large-scale new energy bases cannot meet the demand, resulting in a power shortage. Although electrochemical energy storage can enable the power generation system to meet the above requirements, electrochemical energy storage is expensive and has a short lifespan, requiring frequent replacements.

[0042] After repeated consideration and verification, the inventors discovered that by coupling a thermal power plant with a molten salt energy storage power plant, when renewable energy resources are abundant, the steam generated by the boiler can be transported to the molten salt energy storage power plant. In this case, the molten salt energy storage power plant operates in energy storage mode, reducing the steam input to the turbine in the thermal power plant, thereby lowering the load on the thermal power plant. The steam flowing out of the molten salt energy storage power plant can flow to a device downstream of the turbine in the thermal power plant. When renewable energy resources are insufficient, the steam generated by the boiler flows to the turbine in the thermal power plant, and some of the steam and water flowing out of the turbine can flow to the molten salt energy storage power plant. The steam heated by the molten salt energy storage power plant can then flow to the turbine in the thermal power plant, increasing the rate of load change in the thermal power plant. Furthermore, the molten salt energy storage power plant is also equipped with a turbine. During peak electricity demand periods, the steam generated by the boiler flows to the turbine in the thermal power plant, and the steam from the molten salt energy storage power plant flows to its own turbine. The two turbines drive two generators respectively, ensuring that the power generation system meets the electricity demand. At the same time, the power generation system does not require electrochemical energy storage, which reduces the cost of the power generation system and ensures its service life.

[0043] In view of this, the inventors designed a multi-mode power generation system and its operation method for large-scale new energy bases. This multi-mode power generation system includes a thermal power plant and a molten salt energy storage power plant. The thermal power plant includes a boiler and a first steam turbine. The molten salt energy storage power plant includes a molten salt heating unit, a steam-water heating unit, and a second steam turbine. Steam generated by the boiler can flow to either the first steam turbine or the molten salt heating unit. Steam exiting the steam-water heating unit can flow to either the first steam turbine or the second steam turbine. By adjusting the flow direction of steam in the thermal power plant and the molten salt energy storage power plant, the operating mode of the power generation system can be adjusted, thereby enabling the power generation system to meet more requirements.

[0044] The following describes in detail, with reference to the accompanying drawings, the technical solution of a multi-mode power generation system and its operation method for large-scale new energy bases provided by the present application.

[0045] Reference Figures 2 to 6As shown in the embodiments of this application, the multi-mode power generation system for large-scale new energy bases includes a thermal power plant 100 and a molten salt energy storage power plant 200. The thermal power plant 100 includes a boiler 110, a first steam turbine 120, a first return water unit 130, and a first generator 140. The outlet of the boiler 110 is connected to the inlet of the first steam turbine 120, the first return water unit 130 is connected between the first steam turbine 120 and the boiler 110, and the first generator 140 is connected to the first steam turbine 120. The molten salt energy storage power plant 200 includes a high-temperature molten salt tank 210, a low-temperature molten salt tank 220, a molten salt heating unit 230, a steam-water heating unit 240, a second return water unit 250, a second steam turbine 260, and a second generator 270. The outlet of the low-temperature molten salt tank 220 is connected to the inlet of the molten salt heating unit 230. The first outlet of the molten salt heating unit 230 is connected to the inlet of the high-temperature molten salt tank 210. The outlet of the high-temperature molten salt tank 210 is connected to the first inlet of the steam-water heating unit 240. The outlet of the steam-water heating unit 240 is connected to the inlet of the low-temperature molten salt tank 220. The air inlet of the molten salt heating unit 230 is configured to obtain steam flowing from the boiler 110. The second outlet of the molten salt heating unit 230 is connected to the first return water unit 130. The air outlets of the steam-water heating unit 240 are connected to the first steam turbine 120 and the second steam turbine 260, respectively. The outlet of the second steam turbine 260 is connected to the second return water unit 250. The second generator 270 is connected to the second steam turbine 260. The first return water unit 130 and the second return water unit 250 are connected to the second inlet of the steam-water heating unit 240, respectively.

[0046] Those skilled in the art will understand that when steam enters the first steam turbine 120, the first steam turbine 120 can drive the first generator 140 to generate electricity; when steam enters the second steam turbine 260, the second steam turbine 260 can drive the second generator 270 to generate electricity.

[0047] In one possible implementation, boiler 110 is connected to both first steam turbine 120 and molten salt heating unit 230 via a gas supply pipeline. This gas supply pipeline includes a main pipe, a first branch pipe, and a second branch pipe. The main pipe is connected to boiler 110, the first branch pipe connects the first steam turbine 120 to the main pipe, and the second branch pipe connects the molten salt heating unit 230 to boiler 110. Steam generated by boiler 110 can enter the first steam turbine 120 via the main pipe and the first branch pipe, or it can enter the molten salt heating unit 230 via the main pipe and the second branch pipe.

[0048] For example, such as Figure 1 and Figure 2As shown, the first return water unit 130 includes a condenser 131, multiple low-pressure heating devices 132, a deaerator 133, and multiple high-pressure heating devices 134. The condenser 131 is connected to the first steam turbine 120. The multiple low-pressure heating devices 132 can be sequentially arranged between the condenser 131 and the deaerator 133, and the multiple high-pressure heating devices 134 can be sequentially arranged between the boiler 110 and the deaerator 133. Steam flowing from the first steam turbine 120 can flow to each low-pressure heating device 132 and each high-pressure heating device 134. The condenser 131 collects the condensate discharged from the first steam turbine 120 and each heating device. Each heating device heats the water entering the boiler 110. When steam enters the first steam turbine 120, the first steam turbine 120 can drive the first generator 140 to generate electricity.

[0049] Understandably, the high-temperature molten salt tank 210 is used to store high-temperature molten salt, and the low-temperature molten salt tank 220 is used to store low-temperature molten salt. The molten salt in the low-temperature molten salt tank 220 can flow to the high-temperature molten salt tank 210 via the molten salt heating unit 230. When steam enters the molten salt heating unit 230, it can heat the molten salt flowing within it. For example, as... Figure 2 and Figure 4 As shown, the molten salt heating unit 230 may include multiple molten salt heaters, which are sequentially connected between the high-temperature molten salt tank 210 and the low-temperature molten salt tank 220. Each molten salt heater is provided with an air inlet, a feed inlet, a first discharge outlet, and a second discharge outlet. Steam flows in from the air inlet and flows out from the second discharge outlet, while molten salt flows in from the feed inlet and flows out from the first discharge outlet. By setting the number of molten salt heaters to multiple, the steam discharged from the boiler 110 can be used to achieve staged heating of the tanks, which can improve the energy utilization rate of the power generation system. The molten salt in the high-temperature molten salt tank 210 can flow to the low-temperature molten salt tank 220 via the steam-water heating unit 240. The molten salt flowing in the steam-water heating unit 240 can heat the steam and water entering the steam-water heating unit 240, allowing the steam-water heating unit 240 to discharge steam.

[0050] The multi-mode power generation system provided in this embodiment, such as Figure 5 and Figure 6As shown, when new energy resources are abundant, the operating load of boiler 110 can be reduced to the minimum stable combustion load. The steam generated by boiler 110 can flow to molten salt heating unit 230 to heat the molten salt. At this time, molten salt energy storage power station 200 is in energy storage mode, and the load of the thermal power plant can be further reduced or the thermal power output can be stopped, increasing the proportion of new energy power generation. When new energy resources are insufficient, part of the steam and water in the first return water unit 130 can be heated into steam through steam and water heating unit 240. The steam flowing out of steam and water heating unit 240 can flow together with the steam generated by boiler 110 to the first steam turbine 120, increasing the load change rate of the thermal power plant. When the load of the thermal power plant is close to saturation, the steam and water in the first return water unit 130 can be controlled to not flow to steam and water heating unit 240, or the steam flowing out of steam and water heating unit 240 can be controlled to flow to the second steam turbine 260. During peak electricity consumption periods, steam generated by boiler 110 flows to the first steam turbine 120, and steam generated by steam-water heating unit 240 flows to the second steam turbine 260, enabling the first generator 140 and the second generator 270 to generate electricity simultaneously. At this time, the power generation system operates in peak power generation mode to ensure its output meets electricity demand. After the peak electricity consumption period, molten salt energy storage power station 200 releases all its energy, and the second steam turbine 260 and the second generator 270 cease operation. The energy storage mode is restarted when new energy resources are abundant. In this way, molten salt energy storage power station 200, thermal power station 100, and new energy power station 400 are jointly dispatched and controlled in an integrated manner. This multi-mode power generation system allows the large-scale new energy base to meet higher requirements.

[0051] Using the multi-mode power generation system provided in this embodiment, power can be stably transmitted, the utilization rate of new energy can exceed 90%, and the proportion of new energy in the transmitted electricity exceeds 50%. In addition, the multi-mode power generation system provided in this embodiment does not require the setting of electrochemical energy storage, and the power generation system has low cost, long life and good safety.

[0052] In one embodiment, such as Figure 2 and Figure 4 As shown, the molten salt energy storage power station 200 also includes an electric heater 280. The inlet of the electric heater 280 is connected to the first outlet of the molten salt heating unit 230, the outlet of the electric heater 280 is connected to the inlet of the high-temperature molten salt tank 210, and the electric heater 280 is electrically connected to the new energy power station 400.

[0053] Schematic illustration: The electric heater 280 is equipped with a power curtailment interface for electrical connection to the new energy power station 400, which may include a wind power station or a photovoltaic power station. Understandably, molten salt flowing from the first outlet of the molten salt heating unit 230 can enter the electric heater 280, be heated by the electric heater 280, and then flow to the high-temperature molten salt tank 210. The molten salt energy storage power station 200 has two energy storage modes: steam thermal storage and electric thermal storage. The steam heating power and capacity are matched to the thermal power station 100, while the electric heating power and capacity are matched to the power curtailment situation of the large-scale new energy base.

[0054] During the energy storage process, the steam flowing out of boiler 110 is used to provide a medium- and low-grade heat source so that molten salt heating unit 230 heats molten salt, and the abandoned electricity generated by new energy power station 400 is used to provide a high-grade heat source so that electric heater 280 heats molten salt.

[0055] In this embodiment, by setting up an electric heater 280, when new energy resources are abundant, if the new energy power station 400 has excess electricity that cannot be sent out or consumed, the excess electricity can drive the electric heater 280 to heat the molten salt, and further store the electrical energy in the form of heat energy, so as to realize the consumption and storage of abandoned electricity.

[0056] In one embodiment, such as Figures 2-4 As shown, the steam outlet of the steam heating unit 240 is also connected to the first return water unit 130.

[0057] For example, a gas supply pipe is connected between the first steam turbine 120 and the high-pressure heating device 134, and the steam discharged from the first steam turbine 120 can enter the high-pressure heating device 134 through the gas supply pipe. The gas outlet of the steam-water heating unit 240 can be connected to the first steam turbine 120, the deaerator 133, and the gas supply pipe between the first steam turbine 120 and the high-pressure heating device 134 through the gas outlet pipe.

[0058] In this structure, the steam flowing from the steam-water heating unit 240 can not only flow to the first steam turbine 120 to increase the load change rate of the thermal power plant, but also flow to the high-pressure heating device 134 and the deaerator 133, thus providing a heat source for them. This increases the load ramp-up rate of the boiler 110. If all the steam from the steam-water heating unit 240 flows to the first steam turbine 120, the effect on increasing the load change rate of the thermal power plant is limited due to the limitation of the steam quality. The multi-mode power generation system provided in this embodiment increases the load ramp-up rates of both the boiler 110 and the first steam turbine 120, further improving the load change rate of the thermal power plant.

[0059] In other embodiments, the steam flowing out of the steam heating unit 240 may also flow to the low-pressure heating device 132, which is not the only one.

[0060] In one embodiment, such as Figure 2 and Figure 4 As shown, the steam-water heating unit 240 includes multiple steam heating devices 241 connected in sequence, and the second return water unit 250 includes a peak condenser 131, multiple low-pressure heaters 252, a deaerator 253, and multiple high-pressure heaters 254. The peak condenser 131 is connected to the second steam turbine 260, the multiple low-pressure heaters 252 are connected in sequence between the peak condenser 131 and the deaerator 253, and the multiple high-pressure heaters 254 are connected between the deaerator 253 and the steam-water heating unit 240.

[0061] For example, the number of steam heating devices 241 can be five. For instance, in the direction from the low-temperature molten salt tank 220 to the high-temperature molten salt tank 210, the five steam heating devices 241 are a preheater, a steam generator, a primary steam heater, a secondary steam heater, and a steam superheater. Each steam heating device 241 is provided with a first inlet, a second inlet, an outlet, and a gas outlet. Molten salt flows in from the first inlet and out from the outlet, while steam and water flow in from the second inlet and out from the gas outlet. The steam and water flowing out from the second steam turbine 260 can sequentially flow to the boiler 110 via the peak condenser 131, multiple low-pressure heaters 252, a deaerator 253, and multiple high-pressure heaters 254. Figure 2 and Figure 4 As shown, when the number of steam heating devices 241 is five, the number of low-pressure heaters 252 and high-pressure heaters 254 can both be two. In this embodiment, multiple steam heating devices 241 can heat steam and water in stages to generate steam, improving energy utilization. The steam and water flowing out from the second turbine 260 can flow to the boiler 110 via the second return water unit 250. During this process, the second return water unit 250 can heat the steam and water in stages. The above arrangement can achieve the reuse of steam and water, saving energy; on the other hand, heating the steam and water through the second return water unit 250 helps to increase the amount of steam discharged from the steam and water heating unit 240.

[0062] In a specific embodiment, such as Figure 2 and Figure 4 As shown, the air inlets of each low-pressure heater 252, the deaerator 253, and each high-pressure heater 254 are connected to the air outlets of each steam heating device 241. The drain ports of each low-pressure heater 252 and each high-pressure heater 254 are connected to the peak condenser 131.

[0063] Specifically, the steam flowing out of the preheater can enter one of the low-pressure heaters 252, the steam flowing out of the steam generator can enter another low-pressure heater 252, the steam flowing out of the primary steam heater can enter the deaerator 253, the steam flowing out of the secondary steam heater can enter one of the low-pressure heaters 252, and the steam flowing out of the steam superheater can enter another low-pressure heater 252.

[0064] Optionally, the drain ports of each high-pressure heater 254 and each low-pressure heater 252 can be connected to the peak condenser 131 via pipelines.

[0065] In this embodiment, the steam flowing out of each steam heating device 241 can partially flow to the deaerator 253 and heater of the second return water unit 250. The above arrangement makes the heating curve of the second return water unit 250 relatively flat, reduces the congestion of the second return water unit 250, and improves the thermal efficiency of the molten salt energy storage power station 200.

[0066] In a more specific embodiment, such as Figure 2 and Figure 4 As shown, each low-pressure heater 252 is equipped with a switch valve 310 in the pipeline between the corresponding steam heating device 241, the deaerator 253 and the corresponding steam heating device 241, and the high-pressure heater 254 and the corresponding steam heating device 241.

[0067] Specifically, on the pipeline between the preheater and one of the low-pressure heaters 252, the pipeline between the steam generator and another low-pressure heater 252, the pipeline between the primary steam heater and the deaerator 253, the pipeline between the secondary steam heater and one of the high-pressure heaters 254, and the pipeline between the steam superheater and another high-pressure heater 254, a switch valve 310 is respectively installed.

[0068] In this embodiment, the working status of the low-pressure heater 252, deaerator 253 and high-pressure heater 254 can be controlled by controlling the corresponding switching valve 310. The operator can also control the operation of each device in the second return water unit 250 according to the steam and water temperature discharged from the second turbine 260, thereby improving the flexibility of the molten salt energy storage power station 200.

[0069] like Figures 2-4 As shown, valves 320 are respectively installed on the pipelines between boiler 110 and the first steam turbine 120, the pipelines between boiler 110 and molten salt heating unit 230, and the pipelines between molten salt heating unit 230 and the first return water unit 130.

[0070] In a schematic manner, when renewable energy resources are abundant, operators can close valve 320 on the pipeline between boiler 110 and the first steam turbine 120, open valve 320 on the pipeline between boiler 110 and molten salt heating unit 230, and open valve 320 on the pipeline between molten salt heating unit 230 and the first return water unit 130. At this time, the steam generated by boiler 110 enters molten salt heating unit 230 and flows back to the first return water unit 130, preventing steam from entering the first steam turbine 120 and reducing the load on the thermal power plant.

[0071] When new energy resources are insufficient, staff can open valve 320 on the pipeline between boiler 110 and the first steam turbine 120, and close valve 320 on the pipeline between boiler 110 and molten salt heating unit 230, as well as valve 320 on the pipeline between molten salt heating unit 230 and the first return water unit 130. At this time, the steam generated by boiler 110 enters the first steam turbine 120 to drive the first generator 140 to generate electricity.

[0072] With the above setup, staff can control the operating status of the multi-mode power generation system by controlling valve 320 on the corresponding pipeline.

[0073] Continue to refer to Figures 2-4 Valves 320 are installed on the pipelines between the steam and water heating unit 240 and the first steam turbine 120, the pipelines between the steam and water heating unit 240 and the second steam turbine 260, the pipelines between the first return water unit 130 and the steam and water heating unit 240, and the pipelines between the second return water unit 250 and the steam and water heating unit 240.

[0074] When renewable energy resources are insufficient, valve 320 on the pipeline between steam-water heating unit 240 and the first steam turbine 120, valve 320 on the pipeline between the first return water unit 130 and steam-water heating unit 240, and valve 320 on the pipeline between steam-water heating unit 240 and the second steam turbine 260, and valve 320 on the pipeline between the second return water unit 250 and steam-water heating unit 240 can be closed. At this time, the steam flowing out of steam-water heating unit 240 can enter the first steam turbine 120 to increase the ramp-up rate of thermal power plant 100, that is, to further increase the load change rate of thermal power plant.

[0075] During peak electricity consumption periods, valves 320 on the pipeline between the steam-water heating unit 240 and the first steam turbine 120, and valves 320 on the pipeline between the first return water unit 130 and the steam-water heating unit 240, can be closed respectively. Meanwhile, valves 320 on the pipeline between the steam-water heating unit 240 and the second steam turbine 260, and valves 320 on the pipeline between the second return water unit 250 and the steam-water heating unit 240 can be opened respectively. At this time, the steam flowing from the steam-water heating unit 240 can enter the second steam turbine 260, and the power generation system is in peak power generation mode.

[0076] In this embodiment, by controlling each valve 320, the direction of steam flowing out of the steam-water heating unit 240 can be controlled, so that the molten salt energy storage power station 200 can increase the ramp rate of the thermal power station 100 or drive the second steam turbine 260 to put the power generation system in peak power generation mode.

[0077] This application also provides an operating method applied to the aforementioned multi-mode power generation system, wherein the multi-mode power generation system is coupled with a new energy power plant 400, and the operating method includes:

[0078] When the thermal power plant 100 is in the first state, and the sum of the load of the thermal power plant 100 and the load of the new energy power plant 400 is greater than the power transmission load: adjust the operating load of the boiler 110 to reduce to the minimum stable combustion load, control the steam generated by the boiler 110 to enter the molten salt heating unit 230, and control the steam flowing out of the molten salt heating unit 230 to flow back to the first return water unit 130.

[0079] When the thermal power plant 100 is in the first state, and the total load of the thermal power plant 100 and the load of the new energy power plant 400 is less than the power transmission load: increase the operating load of the boiler 110, control the steam generated by the boiler 110 to enter the first steam turbine 120, control part of the steam and water in the first return water unit 130 to enter the steam and water heating unit 240, and control the steam flowing out of the steam and water heating unit 240 to enter the first steam turbine 120.

[0080] When the thermal power plant 100 is in the second state, and the total load of the thermal power plant 100 and the load of the new energy power plant 400 is less than the power transmission load: control the steam generated by the boiler 110 to enter the first steam turbine 120, control part of the steam and water in the first return water unit 130 to enter the steam and water heating unit 240, and control the steam flowing out of the steam and water heating unit 240 to enter the second steam turbine 260.

[0081] The first state is when boiler 110 reaches the lowest stable combustion load, and boiler 110 drives the first steam turbine 120 to drive the first generator 140 to generate electricity; the second state is when boiler 110 reaches the highest load, and boiler 110 drives the first steam turbine 120 to drive the first generator 140 to generate electricity.

[0082] For example, when the thermal power plant 100 is in the first state, and the sum of the load of the thermal power plant 100 and the load of the new energy power plant 400 is greater than the power transmission load, it indicates that the new energy resources are abundant. At this time, the load of the boiler 110 can be adjusted to 30% of the rated load, i.e., the minimum stable combustion load. When the steam generated by the boiler 110 enters the molten salt heating unit 230, the first steam turbine 120 stops intake, and the thermal power plant 100 stops processing.

[0083] When the thermal power plant 100 is in its first state, the sum of the load of the thermal power plant 100 and the load of the new energy power plant 400 is less than the power transmission load, indicating insufficient new energy resources. The load of the boiler 110 can be gradually increased to 100% of its rated load. The steam flowing out of the steam-water heating unit 240 enters the first steam turbine 120, increasing the ramp-up rate of the thermal power plant 100. Optionally, the steam flowing out of the steam-water heating unit 240 can also enter the first return water unit 130, further increasing the load ramp-up rate of the boiler 110. After the ramp-up rate of the power generation system is increased, there is no need to set up electrochemical energy storage in the power generation system, reducing the cost of the power generation system, and the power generation system has a long lifespan and good safety.

[0084] During peak electricity demand periods, the first turbine 120 and the second turbine 260 operate simultaneously to meet the electricity demand, eliminating the need for electrochemical energy storage in the power generation system and saving on electrochemical energy storage costs.

[0085] The operating method provided in this embodiment allows the power generation system to adjust its working mode according to different needs, enabling the power generation system to achieve a new energy utilization rate of over 90%, a new energy proportion of over 50%, and stable power transmission.

[0086] In one possible implementation, when the load of the new energy power plant 400 is greater than the power supply load, the excess power generated by the new energy power plant 400 is controlled to drive the electric heater 280 to heat the molten salt flowing out of the molten salt heating unit 230.

[0087] Among them, the load of the new energy power station 400 is greater than the power transmission load, indicating that there is a surplus of new energy resources. The molten salt energy storage power station 200 has two heating methods for molten salt: steam heating and electric heating. By setting up an electric heater 280, the surplus of new energy resources can be directly absorbed and stored.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An operating method, characterized in that, A multi-mode power generation system is applied to a large-scale new energy base. The multi-mode power generation system is coupled with a new energy power plant. The multi-mode power generation system includes a thermal power plant and a molten salt energy storage power plant. The thermal power plant includes a boiler, a first steam turbine, a first return water unit, and a first generator. The boiler's outlet is connected to the first steam turbine's inlet. The first return water unit is connected between the first steam turbine and the boiler. The first generator is connected to the first steam turbine. The molten salt energy storage power station includes a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heating unit, a steam-water heating unit, a second return water unit, a second steam turbine, and a second generator. The outlet of the low-temperature molten salt tank is connected to the inlet of the molten salt heating unit. The first outlet of the molten salt heating unit is connected to the inlet of the high-temperature molten salt tank. The outlet of the high-temperature molten salt tank is connected to the first inlet of the steam-water heating unit. The outlet of the steam-water heating unit is connected to the inlet of the low-temperature molten salt tank. The air inlet of the molten salt heating unit is configured to obtain steam flowing out of the boiler, and the second outlet of the molten salt heating unit is connected to the first return water unit; the air outlet of the steam-water heating unit is connected to the first steam turbine and the second steam turbine respectively, the outlet of the second steam turbine is connected to the second return water unit, the second generator is connected to the second steam turbine, and the first return water unit and the second return water unit are respectively connected to the second inlet of the steam-water heating unit; The steam-water heating unit includes multiple steam heating devices connected in sequence. The second return water unit includes a peak condenser, multiple low-pressure heaters, a deaerator, and multiple high-pressure heaters. The peak condenser is connected to the second steam turbine. The multiple low-pressure heaters are connected in sequence between the peak condenser and the deaerator. The multiple high-pressure heaters are connected between the deaerator and the steam-water heating unit. The operating method includes: When the thermal power plant is in the first state, and the sum of the load of the thermal power plant and the load of the new energy power plant is greater than the power transmission load: adjust the operating load of the boiler to reduce it to the minimum stable combustion load, control the steam generated by the boiler to enter the molten salt heating unit, and control the steam flowing out of the molten salt heating unit to flow back to the first return water unit; When the thermal power plant is in the first state, and the sum of the load of the thermal power plant and the load of the new energy power plant is less than the power transmission load: increase the operating load of the boiler, control the steam generated by the boiler to enter the first steam turbine, control part of the steam and water from the first return water unit to enter the steam and water heating unit, and control the steam flowing out of the steam and water heating unit to enter the first steam turbine. When the thermal power plant is in the second state, and the sum of the load of the thermal power plant and the load of the new energy power plant is less than the power transmission load: control the steam generated by the boiler to enter the first steam turbine, control part of the steam and water from the first return water unit to enter the steam and water heating unit, and control the steam flowing out of the steam and water heating unit to enter the second steam turbine; In the first state, the boiler is at its lowest stable combustion load, and the boiler drives the first steam turbine to drive the first generator to generate electricity; in the second state, the boiler is at its highest load, and the boiler drives the first steam turbine to drive the first generator to generate electricity.

2. The operating method according to claim 1, characterized in that, The molten salt energy storage power station also includes an electric heater. The inlet of the electric heater is connected to the first outlet of the molten salt heating unit, and the outlet of the electric heater is connected to the inlet of the high-temperature molten salt tank. The electric heater is electrically connected to the new energy power station.

3. The operating method according to claim 1, characterized in that, The steam outlet of the steam heating unit is also connected to the first return water unit.

4. The operating method according to claim 1, characterized in that, The air inlets of each of the low-pressure heaters, the deaerators, and the high-pressure heaters are respectively connected to the air outlets of each of the steam heating devices. The drain outlets of each of the low-pressure heaters and the high-pressure heaters are respectively connected to the peak condenser.

5. The operating method according to claim 4, characterized in that, Each of the low-pressure heaters and the corresponding steam heating device, the deaerator and the corresponding steam heating device, and the high-pressure heater and the corresponding steam heating device are equipped with a switch valve.

6. The operating method according to any one of claims 1-5, characterized in that, Valves are respectively installed on the pipeline between the boiler and the first steam turbine, the pipeline between the boiler and the molten salt heating unit, and the pipeline between the molten salt heating unit and the first return water unit.

7. The operating method according to claim 6, characterized in that, Valves are installed on the pipelines between the steam and water heating unit and the first steam turbine, the pipelines between the steam and water heating unit and the second steam turbine, the pipelines between the first return water unit and the steam and water heating unit, and the pipelines between the second return water unit and the steam and water heating unit.

8. The operating method according to claim 1, characterized in that, When the load of the new energy power station is greater than the power supply load, the excess electricity generated by the new energy power station is controlled to drive the electric heater to heat the molten salt flowing out of the molten salt heating unit.

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