Coal-fired power plant based on fused salt heat storage, power generation system and operation method

Abstract

The invention relates to the technical field of thermal power generation, in particular to a coal-fired power plant based on fused salt heat storage, a power generation system and an operation method. The coal-fired power plant comprises a boiler, a steam turbine, a condenser, a deaerator, a first heating unit, a second heating unit and a generator. The coal-fired power plant is further provided with a first pipeline, a second pipeline, a third pipeline and a fourth pipeline, one end of the first pipeline is connected to the pipeline between the boiler and the steam turbine, and the other end of the first pipeline is connected with an air inlet of the fused salt heating unit. One end of the second pipeline is connected with an air outlet of the fused salt heating unit, and the other end is connected with the condenser; one end of the third pipeline is connected with the deaerator, and the other end is connected with an air inlet of the steam generation unit; one end of the fourth pipeline is connected with an air outlet of the steam generation unit, and the other end is connected with the turbine and the first heating unit. And the peak regulation depth and the variable load rate of the coal-fired power plant are improved.

Description

Technical Field

[0001] This application relates to the technical field of thermal power generation, and particularly to a coal-fired power station, a power generation system, and an operation method based on molten salt energy storage. Background Art

[0002] A large-scale renewable energy base refers to a large-scale energy base where multiple types of power sources such as wind power, photovoltaic power, thermal power, and energy storage facilities are constructed synchronously, connected to the grid synchronously, jointly dispatched, and bundled for transmission. Among them, the base thermal power mainly plays the role of flattening the new energy curve and peak shaving and peaking.

[0003] Currently, large-scale renewable energy bases include coal-fired power stations and new energy power stations, and the coal-fired power stations are coupled with the new energy power stations. When there is abundant new energy resources, the load of the coal-fired power station is controlled to decrease; when there is insufficient new energy resources, the load of the coal-fired power station is increased. By flexibly dispatching the operation mode of the coal-fired power station, the large-scale renewable energy base can supply power smoothly.

[0004] However, the peak shaving depth of the coal-fired power station is insufficient, which will lead to curtailment of new energy when there is abundant new energy resources, and the load change rate of the coal-fired power station is insufficient, affecting the stability of the power grid. Summary of the Invention

[0005] Based on this, this application provides a coal-fired power station, a power generation system, and an operation method based on molten salt energy storage to solve the problems of insufficient peak shaving depth and insufficient load change rate of the coal-fired power station in the related art.

[0006] In the first aspect, this application provides a coal-fired power station based on molten salt energy storage. The coal-fired power station is coupled with a molten salt energy storage module and a new energy power station respectively. The molten salt energy storage module is provided with a steam generation unit and a molten salt heating unit;

[0007] The coal-fired power station includes a boiler, a steam turbine, a condenser, a deaerator, a first heating unit, a second heating unit, and a generator. The inlet of the steam turbine is connected to the boiler, the steam turbine is connected to the generator, the inlet of the condenser is connected to the outlet of the steam turbine, the first heating unit is connected between the condenser and the deaerator, and the second heating unit is connected between the deaerator and the boiler;

[0008] Wherein, the coal-fired power station is further provided with a first pipeline, a second pipeline, a third pipeline, and a fourth pipeline. One end of the first pipeline is connected to the pipeline between the boiler and the steam turbine, and the other end of the first pipeline is connected to the inlet of the molten salt heating unit; one end of the second pipeline is connected to the outlet of the molten salt heating unit, and the other end of the second pipeline is connected to the condenser; one end of the third pipeline is connected to the deaerator, and the other end of the third pipeline is connected to the inlet of the steam generation unit; one end of the fourth pipeline is connected to the outlet of the steam generation unit, and the other end of the fourth pipeline is connected to the steam turbine and the first heating unit respectively.

[0009] In a possible implementation, the steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected in sequence. The high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder are all configured to drive a generator to generate electricity. The inlet of the high-pressure cylinder is connected to the boiler, the outlet of the high-pressure cylinder is connected to the boiler, and the inlet of the intermediate-pressure cylinder is connected to the boiler.

[0010] In a possible implementation, the pipeline between the inlet of the high-pressure cylinder and the boiler and the pipeline between the inlet of the intermediate-pressure cylinder and the boiler are respectively connected to one end of the first pipeline.

[0011] In a possible implementation, the pipeline between the outlet of the high-pressure cylinder and the boiler is connected to the other end of the fourth pipeline.

[0012] In a possible implementation, the other end of the fourth pipeline is connected to the inlet of the intermediate-pressure cylinder.

[0013] In a possible implementation, the first heating unit includes a first low-pressure heater, at least one second low-pressure heater, and at least one third low-pressure heater connected in sequence. The first low-pressure heater is located between the second low-pressure heater and the condenser, the third low-pressure heater is located between the second low-pressure heater and the deaerator, and the other end of the fourth pipeline is also connected to the first low-pressure heater.

[0014] In a possible implementation, the second heating unit includes a plurality of high-pressure heaters connected in sequence. The outlet of the high-pressure cylinder is respectively connected to each high-pressure heater, the outlet of the intermediate-pressure cylinder is respectively connected to each third low-pressure heater, and the outlet of the low-pressure cylinder is respectively connected to each second low-pressure heater.

[0015] In a possible implementation, the other end of the fourth pipeline is also connected to the deaerator.

[0016] In a second aspect, the present application further provides a power generation system, including a molten salt energy storage module and the above-mentioned coal-fired power station. The molten salt energy storage module includes a high-temperature molten salt tank, a low-temperature molten salt tank, a steam generation unit, and a molten salt heating unit. The molten salt heating unit is connected between the outlet of the low-temperature molten salt tank and the inlet of the high-temperature molten salt tank, and the steam generation unit is connected between the outlet of the high-temperature molten salt tank and the inlet of the low-temperature molten salt tank.

[0017] In a third aspect, the present application further provides an operation method for a coal-fired power station, which is applied to the above-mentioned coal-fired power station. The operation method includes:

[0018] When the coal-fired power plant is in the first state and the sum of the loads of the coal-fired power plant and the new energy power plant is greater than the power transmission load: adjust the operating load of the boiler to the lowest stable combustion load, and control the steam generated by the boiler to enter the molten salt heating unit of the molten salt energy storage power plant through the first pipeline. The steam discharged from the molten salt heating unit enters the condenser through the second pipeline;

[0019] When the coal-fired power plant is in the first state and the sum of the loads of the coal-fired power plant and the new energy power plant is less than the power transmission load: increase the operating load of the boiler, and part of the steam-water mixture discharged from the deaerator enters the steam generation unit of the molten salt energy storage power plant through the third pipeline. The steam discharged from the steam generation unit enters the steam turbine and the first heating unit respectively through the fourth pipeline;

[0020] Among them, the first state is that the boiler reaches the lowest stable combustion load, and all the steam discharged from the boiler enters the steam turbine.

[0021] A coal-fired power plant, a power generation system and an operation method based on molten salt heat storage provided by the present application. The coal-fired power plant is coupled with the molten salt energy storage module and the new energy power plant respectively. When the load of the new energy power plant is high, that is, when the new energy resources are abundant, the load of the boiler can be reduced to the lowest stable combustion load, and the steam discharged from the boiler can be transported to the molten salt heating unit through the first pipeline. After the steam is discharged from the molten salt heating unit, it can be transported to the condenser through the second pipeline. By heating the molten salt with steam, at this time, the molten salt energy storage module is in the energy storage mode, the intake air volume of the steam turbine is reduced or the intake air is stopped, the load of the coal-fired power plant is reduced or the coal-fired power plant stops outputting power, increasing the peak shaving depth of the coal-fired power plant. When the load of the new energy power plant is low, that is, when the new energy resources are insufficient, increase the load of the boiler, and the steam discharged from the boiler is transported to the steam turbine. Part of the steam-water mixture discharged from the deaerator can be transported to the steam generation unit through the third pipeline. At this time, the molten salt energy storage module releases energy, and the steam discharged from the molten salt energy storage module is transported to the steam turbine and the first heating unit respectively through the fourth pipeline. In this way, the steam discharged from the molten salt energy storage module can be used to increase the ramp rate of the coal-fired power plant and the variable load rate of the coal-fired power plant. Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is the output curve of the coal-fired power plant in the related art;

[0024] Figure 2 It is the output schematic diagram of the large-scale wind-solar base in the related art;

[0025] Figure 3 Schematic diagram of the power generation system provided by the embodiment of the present application;

[0026] Figure 4 Schematic diagram of the coal-fired power station provided by the embodiment of the present application;

[0027] Figure 5 Output schematic diagram of the large-scale wind and solar base provided by the embodiment of the present application.

[0028] Explanation of reference numerals:

[0029] 100 - Coal-fired power station; 110 - Boiler; 120 - Steam turbine; 121 - High-pressure cylinder; 122 - Intermediate-pressure cylinder; 123 - Low-pressure cylinder; 130 - Condenser; 140 - Deaerator; 150 - First heating unit; 151 - First low-pressure heater; 152 - Second low-pressure heater; 153 - Third low-pressure heater; 160 - Second heating unit; 161 - High-pressure heater; 170 - Generator; 181 - First pipeline; 182 - Second pipeline; 183 - Third pipeline; 184 - Fourth pipeline;

[0030] 200 - Molten salt energy storage module; 210 - Steam generation unit; 220 - Molten salt heating unit; 230 - High-temperature molten salt tank; 240 - Low-temperature molten salt tank. Detailed implementation manners

[0031] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals represent the same or similar components or components with the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present application. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0032] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, or an indirect connection through an intermediate medium, or the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0033] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0034] In the description and claims of the present application and the above-mentioned drawings, the terms "first", "second", "third" (if any) are used to distinguish similar objects and do not necessarily describe a specific order or sequence.

[0035] In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or display comprising a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or displays.

[0036] In the prior art, large-scale wind-solar bases include coal-fired power plants and new energy power plants, and the coal-fired power plants are coupled with the new energy power plants. When new energy resources are abundant, the load of the coal-fired power plants is controlled to decrease; when new energy resources are insufficient, the load of the coal-fired power plants is increased. By flexibly scheduling the operation mode of the coal-fired power plants, the large-scale wind-solar bases can supply power smoothly. However, as Figure 1 and Figure 2 shown, the load of the coal-fired power plants is limited by the minimum stable combustion load of their boilers. For example, the minimum stable combustion load of a boiler is 30% of its rated load, and the load of the coal-fired power plant can be peak-shaved up to 30% of its rated load at most, resulting in insufficient peak-shaving depth of the coal-fired power plants and new energy curtailment when new energy resources are abundant. The dispatching instruction of the existing large-scale wind-solar bases is about 5% pe / min, and the response rate of the coal-fired power plants is generally 1%-1.5% pe / min. Electrochemical energy storage devices also need to be installed in the large-scale wind-solar bases, increasing the cost of the large-scale wind-solar bases.

[0037] After repeated thinking and verification, the inventor found that if a coal-fired power station is coupled with a molten salt energy storage module and a new energy power station respectively. Four pipelines, namely the first pipeline, the second pipeline, the third pipeline and the fourth pipeline, are arranged between the coal-fired power station and the molten salt energy storage module. When there is abundant new energy resources, the load of the boiler of the coal-fired power station can be controlled to be reduced to the lowest stable combustion load. The steam originally entering the steam turbine is passed into the molten salt heating unit of the molten salt energy storage module through the first pipeline, and the steam discharged from the molten salt energy storage module is passed into the condenser of the coal-fired power station through the second pipeline. In this way, the intake of the steam turbine is reduced or stopped, and the load of the coal-fired power station is not limited by the lowest stable combustion load of the boiler, the peak shaving depth of the coal-fired power station is increased, and more new energy power generation can be connected to the grid. When there is insufficient new energy resources, the load of the boiler can be increased. Part of the steam-water discharged from the deaerator can enter the steam generation unit through the third pipeline, and the steam discharged from the steam generation unit can be sent to the steam turbine and the first heating unit respectively through the fourth pipeline. In this way, the steam discharged from the steam generation unit can be used to increase the ramp rate of the coal-fired power station, that is, to increase the variable load rate of the coal-fired power station, which is beneficial to the power generation system to reduce the cost of electrochemical energy storage.

[0038] In view of this, the inventor designed a coal-fired power station, a power generation system and an operation method based on molten salt heat storage. The coal-fired power station is coupled with a molten salt energy storage module and a new energy power station respectively. The molten salt energy storage module is provided with a steam generation unit and a molten salt heating unit. The coal-fired power station is provided with a first pipeline, a second pipeline, a third pipeline and a fourth pipeline. The first pipeline is used for the steam discharged from the boiler of the coal-fired power station to enter the molten salt heating unit; the second pipeline is used for the steam discharged from the molten salt heating unit to enter the condenser of the coal-fired power station; the third pipeline is used for part of the steam-water discharged from the deaerator to enter the steam generation unit; the fourth pipeline is used for the steam discharged from the steam generation unit to enter the steam turbine and the first heating unit respectively. In this way, the steam originally entering the steam turbine can enter the molten salt heating unit through the first pipeline, and the steam turbine can stop intake or further reduce intake, increasing the peak shaving depth of the coal-fired power station; the steam discharged from the steam generation unit can enter the coal-fired power station through the fourth pipeline, increasing the variable load rate of the coal-fired power station.

[0039] The technical solutions of a coal-fired power station, a power generation system and an operation method based on molten salt heat storage provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0040] Refer to Figures 3 to 5As shown in the figure, a coal-fired power plant 100 provided by an embodiment of the present application is based on molten salt thermal energy storage. The coal-fired power plant 100 is coupled with a molten salt energy storage module 200 and a new energy power plant respectively. The molten salt energy storage module 200 is provided with a steam generation unit 210 and a molten salt heating unit 220. The coal-fired power plant 100 includes a boiler 110, a steam turbine 120, a condenser 130, a deaerator 140, a first heating unit 150, a second heating unit 160, and a generator 170. The intake port of the steam turbine 120 is connected to the boiler 110, the steam turbine 120 is connected to the generator 170, the intake port of the condenser 130 is connected to the outlet of the steam turbine 120, the first heating unit 150 is connected between the condenser 130 and the deaerator 140, and the second heating unit 160 is connected between the deaerator 140 and the boiler 110. Among them, the coal-fired power plant 100 is further provided with a first pipeline 181, a second pipeline 182, a third pipeline 183, and a fourth pipeline 184. One end of the first pipeline 181 is connected to the pipeline between the boiler 110 and the steam turbine 120, and the other end of the first pipeline 181 is connected to the intake port of the molten salt heating unit 220. One end of the second pipeline 182 is connected to the outlet of the molten salt heating unit 220, and the other end of the second pipeline 182 is connected to the condenser 130. One end of the third pipeline 183 is connected to the deaerator 140, and the other end of the third pipeline 183 is connected to the intake port of the steam generation unit 210. One end of the fourth pipeline 184 is connected to the outlet of the steam generation unit 210, and the other end of the fourth pipeline 184 is connected to the steam turbine 120 and the first heating unit 150 respectively.

[0041] Among them, the load of the boiler 110 can be adjusted between the minimum stable combustion load and the rated load. In a possible implementation manner, valves can be respectively arranged on the pipeline between the boiler 110 and the steam turbine 120 and the first pipeline 181. By controlling the two valves, it can be controlled that all the steam discharged from the boiler 110 enters the steam turbine 120, all enters the molten salt heating unit 220 via the first pipeline 181, or part enters the steam turbine 120 and part enters the molten salt heating unit 220 via the first pipeline 181. It can be understood that when the steam enters the molten salt heating unit 220, it can heat the molten salt flowing in the molten salt heating unit 220. It can be understood that the steam that originally entered the steam turbine 120 enters the molten salt heating unit 220 through the first pipeline 181, realizing the decoupling of the steam turbine 120 and the boiler 110, enabling the generator 170 to further reduce power generation or stop power generation, which helps to reduce the load of the coal-fired power plant 100.

[0042] Exemplarily, valves can be respectively arranged on the third pipeline 183 and the fourth pipeline 184. After a part of the steam-water discharged from the deaerator 140 enters the steam generation unit 210, the molten salt flowing in the steam generation unit 210 can heat the steam-water discharged from the deaerator 140 so that the steam generation unit 210 can discharge steam. It is worth mentioning that the steam entering the steam turbine 120 through the fourth pipeline 184 can directly increase the load of the coal-fired power plant 100, and thus the load change rate of the coal-fired power plant 100. The steam entering the first heating unit 150 through the fourth pipeline 184 helps to rapidly increase the load of the boiler 110, further increasing the load change rate of the coal-fired power plant 100.

[0043] In the coal-fired power plant 100 provided in this embodiment, when the load of the new energy power plant is high, that is, when the new energy resources are abundant, the load of the boiler 110 can be reduced to the minimum stable combustion load. The steam discharged from the boiler 110 can be transported to the molten salt heating unit 220 through the first pipeline 181. After the steam is discharged from the molten salt heating unit 220, it can be transported to the condenser 130 through the second pipeline 182. By heating the molten salt with steam, at this time, the molten salt energy storage module 200 is in the energy storage mode. As Figure 5 shown, the intake air volume of the steam turbine 120 is reduced or the intake air is stopped, the power generation of the generator 170 is reduced or the generator 170 is stopped from generating power, and thus the load of the coal-fired power plant 100 is reduced or the coal-fired power plant 100 stops outputting power, increasing the peak shaving depth of the coal-fired power plant 100. When the load of the new energy power plant is low, that is, when the new energy resources are insufficient, the load of the boiler 110 is increased. The steam discharged from the boiler 110 is transported to the steam turbine 120. A part of the steam-water discharged from the deaerator 140 can be transported to the steam generation unit 210 through the third pipeline 183. At this time, the molten salt energy storage module 200 releases energy. The steam discharged from the molten salt energy storage module 200 is respectively transported to the steam turbine 120 and the first heating unit 150 through the fourth pipeline 184. In this way, the use of the steam discharged from the molten salt energy storage module 200 can increase the ramp rate of the coal-fired power plant 100 and increase the load change rate of the coal-fired power plant 100.

[0044] In one embodiment, as Figure 3 and Figure 4 shown, the steam turbine 120 includes a high-pressure cylinder 121, an intermediate-pressure cylinder 122, and a low-pressure cylinder 123 that are connected in sequence. The high-pressure cylinder 121, the intermediate-pressure cylinder 122, and the low-pressure cylinder 123 are all configured to drive the generator 170 to generate power. The intake port of the high-pressure cylinder 121 is connected to the boiler 110, the outlet port of the high-pressure cylinder 121 is connected to the boiler 110, and the intake port of the intermediate-pressure cylinder 122 is connected to the boiler 110.

[0045] Exemplarily, the high-pressure cylinder 121, the intermediate-pressure cylinder 122, and the low-pressure cylinder 123 are connected to the power shaft, and the output end of the power shaft is connected to the generator 170. Among them, the steam discharged from the boiler 110 can enter the high-pressure cylinder 121 and the intermediate-pressure cylinder 122 respectively. The steam discharged from the high-pressure cylinder 121 can return to the boiler 110 for reheating, and the steam discharged from the intermediate-pressure cylinder 122 can enter the low-pressure cylinder 123.

[0046] In this structure, the pressure and temperature of the steam entering the high-pressure cylinder 121, the intermediate-pressure cylinder 122, and the low-pressure cylinder 123 gradually decrease. Through the above settings, the energy of the steam discharged from the boiler 110 can be utilized more fully, and the energy utilization rate of the coal-fired power station 100 can be improved.

[0047] In a specific embodiment, as Figure 3 and Figure 4 shown, the pipelines between the inlet of the high-pressure cylinder 121 and the boiler 110 and between the inlet of the intermediate-pressure cylinder 122 and the boiler 110 are respectively connected to one end of the first pipeline 181.

[0048] Exemplarily, one end of the first pipeline 181 is respectively provided with a first branch pipe and a second branch pipe. The first branch pipe is connected to the pipeline between the inlet of the high-pressure cylinder 121 and the boiler 110, and the second branch pipe is connected to the pipeline between the inlet of the intermediate-pressure cylinder 122 and the boiler 110. Optionally, valves can be respectively provided on the first branch pipe and the second branch pipe.

[0049] Through the above settings, when the new energy resources are abundant, the steam that originally enters the steam turbine 120 can partially or completely enter the molten salt heating unit 220 of the molten salt energy storage module 200 through the first pipeline 181. The first pipeline 181 can extract the steam discharged from the boiler 110 separately through the first branch pipe or separately through the second branch pipe, or the first pipeline 181 can extract the steam discharged from the boiler 110 through the first branch pipe and the second branch pipe at the same time. When the load of the new energy power station is not less than the power transmission load, the coal-fired power station 100 can be made to stop outputting power.

[0050] In a specific embodiment, as Figure 3 and Figure 4 shown, the pipeline between the outlet of the high-pressure cylinder 121 and the boiler 110 is connected to the other end of the fourth pipeline 184.

[0051] Exemplarily, the outlet of the high-pressure cylinder 121 can be connected to the boiler 110 through a return pipeline. It can be understood that in addition to entering the steam turbine 120 and the first heating unit 150 respectively through the fourth pipeline 184, the steam discharged from the steam generation unit 210 can also enter the return pipeline through the fourth pipeline 184. In this way, the steam discharged from the steam generation unit 210 can also increase the temperature of the steam entering the boiler 110, which is beneficial to increasing the load lifting speed of the boiler 110.

[0052] In a specific embodiment, the other end of the fourth pipeline 184 is connected to the inlet of the intermediate-pressure cylinder 122.

[0053] Among them, the quality (temperature and pressure) of the steam discharged from the steam generation unit 210 is lower than the quality of the steam required for the high-pressure cylinder 121 to do work; the quality of the steam discharged from the steam generation unit 210 is higher than or equal to the quality of the steam required for the intermediate-pressure cylinder 122 to do work. In this way, the steam discharged from the steam generation unit 210 can be used to drive the intermediate-pressure cylinder 122 to do work.

[0054] Through the above settings, the steam discharged from the steam generation unit 210 will not affect the function of the high-pressure cylinder 121, ensuring that the steam entering the steam turbine 120 from the steam generation unit 210 can reliably drive the steam turbine 120 to function, and thus reliably increase the load of the coal-fired power station 100.

[0055] Figure 3 and Figure 4 It is shown that the first heating unit 150 includes a first low-pressure heater 151, at least one second low-pressure heater 152, and at least one third low-pressure heater 153 connected in sequence. The first low-pressure heater 151 is located between the second low-pressure heater 152 and the condenser 130, the third low-pressure heater 153 is located between the second low-pressure heater 152 and the deaerator 140, and the other end of the fourth pipeline 184 is also connected to the first low-pressure heater 151.

[0056] It can be understood that the condensed water flowing out of the condenser 130 flows through the first low-pressure heater 151, each second low-pressure heater 152, and each third low-pressure heater 153 in sequence and then enters the deaerator 140, and the condensed water is gradually heated through the low-pressure heaters of the first heating unit 150. It can be understood that the temperature of the condensed water flowing out of the condenser 130 when it enters the first low-pressure heater 151 is lower than the temperature of the steam discharged from the steam generation unit 210. In the first low-pressure heater 151, the steam discharged from the steam generation unit 210 exchanges heat with the condensed water flowing out of the condenser 130 to heat the condensed water.

[0057] In this structure, the temperature of the steam discharged by the steam generation unit 210 through the fourth pipeline 184 is higher than the temperature of the condensate when it flows out of the condenser 130. That is, the steam discharged by the steam generation unit 210 can reliably heat the condensate flowing out of the condenser 130 for the first time to increase the rate of increase of the load of the boiler 110.

[0058] Schematically, the second heating unit 160 includes a plurality of high-pressure heaters 161 connected in sequence. The outlet of the high-pressure cylinder 121 is respectively connected to each high-pressure heater 161, the outlet of the intermediate-pressure cylinder 122 is respectively connected to each third low-pressure heater 153, and the outlet of the low-pressure cylinder 123 is respectively connected to each second low-pressure heater 152.

[0059] Among them, the condensate flowing out of the deaerator 140 flows through each high-pressure heater 161 in sequence and then enters the boiler 110. It can be understood that the temperature of the steam flowing out of the high-pressure cylinder 121 is greater than the temperature of the steam flowing out of the intermediate-pressure cylinder 122 is greater than the temperature of the steam flowing out of the low-pressure cylinder 123. In this embodiment, the specific numbers of the second low-pressure heater 152, the third low-pressure heater 153, and the high-pressure heater 161 are not limited, and those skilled in the art can set them according to actual needs.

[0060] In a possible implementation manner, each high-pressure heater 161 is provided with a drain port. After the steam flowing out of the high-pressure cylinder 121 exchanges heat with the condensate in the high-pressure heater 161, it can flow out from the drain port to the deaerator 140. Each low-pressure heater is also provided with a drain port. After the steam exchanges heat with the condensate in the low-pressure heater, it can flow out from the drain port to the condenser 130.

[0061] In this structure, after the steam discharged by the steam generation unit 210 heats the condensate for the first time, the steam flowing out of each cylinder in the steam turbine 120 is used to heat the condensate step by step to improve the energy utilization rate of the coal-fired power station 100.

[0062] Such as Figure 3 and Figure 4 shown, the other end of the fourth pipeline 184 is also connected to the deaerator 140.

[0063] It can be understood that after the steam discharged by the steam generation unit 210 is introduced into the deaerator 140, it can also remove the oxygen in the condensate in the deaerator 140. In a specific implementation manner, four branches are respectively provided at the end of the fourth pipeline 184 far from the steam generation unit 210, and the four branches are respectively connected to the intermediate-pressure cylinder 122 of the steam turbine 120, the first low-pressure heater 151, the pipeline between the outlet of the high-pressure cylinder 121 and the boiler 110, and the deaerator 140.

[0064] With the above settings, the steam discharged by the steam generation unit 210 is used to remove oxygen in the condensate water, which can further increase the ramp-up rate of the boiler 110 load, and thus further increase the ramp-up rate of the coal-fired power station 100.

[0065] For the coal-fired power station provided in this embodiment, comparing with the data of the coal-fired power station in the related art, the results are shown in Table 1 below:

[0066] Table 1

[0067]

[0068] As can be seen from Table 1, the flexibility of the coal-fired power station provided in this embodiment increases, and the electrochemical energy storage configured in the large-scale wind-solar base can be appropriately reduced, thereby reducing the investment in the large-scale wind-solar base. Exemplarily, the variable load rate of the coal-fired power station can be increased from 1-1.5% pe / min to 3% pe / min, and at least 250,000 kWh of electrochemical energy storage in the base storage configuration can be reduced.

[0069] On the other hand, the present application also provides a power generation system, including a molten salt energy storage module 200 and the above-mentioned coal-fired power station 100. The molten salt energy storage module 200 includes a high-temperature molten salt tank 230, a low-temperature molten salt tank 240, a steam generation unit 210, and a molten salt heating unit 220. The molten salt heating unit 220 is connected between the discharge port of the low-temperature molten salt tank 240 and the feed port of the high-temperature molten salt tank 230, and the steam generation unit 210 is connected between the discharge port of the high-temperature molten salt tank 230 and the feed port of the low-temperature molten salt tank 240.

[0070] It can be understood that the high-temperature molten salt tank 230 is used to store high-temperature molten salt, and the low-temperature molten salt tank 240 is used to store low-temperature molten salt. Schematically, the molten salt heating unit 220 includes a plurality of sequentially connected molten salt heating devices, and the steam generation unit 210 includes a plurality of sequentially connected steam generation devices. When the steam generated by the boiler 110 enters the molten salt heating unit 220 through the first pipeline 181, the steam exchanges heat with the low-temperature molten salt flowing out of the low-temperature molten salt tank 240. The steam after heat exchange flows out through the second pipeline 182, and the high-temperature molten salt formed after heat exchange is stored in the high-temperature molten salt tank 230. When the steam-water mixture or condensate discharged from the deaerator 140 enters the steam generation unit 210 through the third pipeline 183, the high-temperature molten salt flowing into the steam generation unit 210 from the high-temperature molten salt tank 230 exchanges heat with the steam-water mixture or condensate. The low-temperature molten salt formed after heat exchange is stored in the low-temperature molten salt tank 240, and the steam formed after heat exchange of the steam-water mixture or condensate is discharged through the fourth pipeline 184.

[0071] The power generation system provided by this application can control the operating modes of the coal-fired power plant 100 and the molten salt energy storage module 200 according to the load of the new energy power station. When the new energy resources are abundant, the output of the coal-fired power plant 100 can be reduced or the coal-fired power plant 100 can be stopped from outputting, reducing the abandonment of new energy. When the new energy resources are insufficient, the molten salt energy storage module 200 releases energy, and the steam discharged from the molten salt energy storage module 200 can increase the load change rate of the coal-fired power plant 100, reducing the electrochemical energy storage configured in large-scale wind-solar bases and saving the costs of large-scale wind-solar bases.

[0072] This application also provides an operating method for the coal-fired power plant 100, which is applied to the above-mentioned coal-fired power plant 100. The operating method includes:

[0073] When the coal-fired power plant 100 is in the first state and the sum of the load of the coal-fired power plant 100 and the load of the new energy power station is greater than the power transmission load: adjust the operating load of the boiler 110 to decrease to the lowest stable combustion load, and control the steam generated by the boiler 110 to enter the molten salt heating unit 220 of the molten salt energy storage power station through the first pipeline 181. The steam discharged from the molten salt heating unit 220 enters the condenser 130 through the second pipeline 182;

[0074] When the coal-fired power plant 100 is in the first state and the sum of the load of the coal-fired power plant 100 and the load of the new energy power station is less than the power transmission load: increase the operating load of the boiler 110, and part of the steam-water mixture discharged from the deaerator 140 enters the steam generation unit 210 of the molten salt energy storage power station through the third pipeline 183. The steam discharged from the steam generation unit 210 enters the steam turbine 120 and the first heating unit 150 respectively through the fourth pipeline 184;

[0075] Among them, the first state is that the boiler 110 reaches the lowest stable combustion load, and all the steam discharged from the boiler 110 enters the steam turbine 120.

[0076] When the coal-fired power plant 100 is in the first state and the sum of the load of the coal-fired power plant 100 and the load of the new energy power station is greater than the power transmission load, it indicates that more new energy is generated, that is, the new energy resources are abundant. The steam that originally entered the steam turbine 120 enters the molten salt heating unit 220 through the first pipeline 181, realizing the structure between the steam turbine 120 and the boiler 110. The work done by the steam turbine 120 is further reduced or stopped, reducing the abandonment of new energy.

[0077] When the coal-fired power plant 100 is in the first state and the sum of the load of the coal-fired power plant 100 and the load of the new energy power station is less than the power transmission load, it indicates that less new energy is generated and the new energy resources are insufficient. The steam discharged from the steam generation unit 210 increases the ramp rate of the coal-fired power plant 100, reducing the electrochemical energy storage configured in large-scale wind-solar bases and saving the costs of large-scale wind-solar bases.

[0078] For the operation method provided in this embodiment, the working mode of the coal-fired power station 100 can be set according to different needs. When new energy resources are sufficient, the curtailment of new energy can be reduced. At the same time, the molten salt energy storage module 200 can also improve the load change rate of the coal-fired power station 100, reduce the electrochemical energy storage configured in large-scale wind-solar bases, and reduce the investment in large-scale wind-solar bases.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A coal-fired power station based on molten salt thermal energy storage, characterized in that, The coal-fired power station is coupled with a molten salt energy storage module and a new energy power station respectively. The molten salt energy storage module is provided with a steam generation unit and a molten salt heating unit; The coal-fired power station includes a boiler, a steam turbine, a condenser, a deaerator, a first heating unit, a second heating unit and a generator. The inlet of the steam turbine is connected to the boiler, the steam turbine is connected to the generator, the inlet of the condenser is connected to the outlet of the steam turbine, the first heating unit is connected between the condenser and the deaerator, and the second heating unit is connected between the deaerator and the boiler; Wherein, the coal-fired power station is further provided with a first pipeline, a second pipeline, a third pipeline and a fourth pipeline. One end of the first pipeline is connected to the pipeline between the boiler and the steam turbine, and the other end of the first pipeline is connected to the inlet of the molten salt heating unit; One end of the second pipeline is connected to the outlet of the molten salt heating unit, and the other end of the second pipeline is connected to the condenser; One end of the third pipeline is connected to the deaerator, and the other end of the third pipeline is connected to the inlet of the steam generation unit; One end of the fourth pipeline is connected to the outlet of the steam generation unit, and the other end of the fourth pipeline is connected to the steam turbine and the first heating unit respectively.

2. The coal-fired power station according to claim 1, characterized in that, The steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder connected in sequence. The high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder are all configured to drive the generator to generate electricity. The inlet of the high-pressure cylinder is connected to the boiler, the outlet of the high-pressure cylinder is connected to the boiler, and the inlet of the intermediate-pressure cylinder is connected to the boiler.

3. The coal-fired power station according to claim 2, characterized in that The pipelines between the inlet of the high-pressure cylinder and the boiler and between the inlet of the intermediate-pressure cylinder and the boiler are respectively connected to one end of the first pipeline.

4. The coal-fired power station according to claim 2, characterized in that, The pipeline between the outlet of the high-pressure cylinder and the boiler is connected to the other end of the fourth pipeline.

5. The coal-fired power station according to claim 2, wherein The other end of the fourth pipeline is connected to the inlet of the intermediate-pressure cylinder.

6. The coal-fired power station according to claim 2, wherein The first heating unit includes a first low-pressure heater, at least one second low-pressure heater and at least one third low-pressure heater connected in sequence. The first low-pressure heater is located between the second low-pressure heater and the condenser, the third low-pressure heater is located between the second low-pressure heater and the deaerator, and the other end of the fourth pipeline is further connected to the first low-pressure heater.

7. The coal-fired power station according to claim 6, characterized in that, The second heating unit includes a plurality of high-pressure heaters connected in sequence. The outlet of the high-pressure cylinder is respectively connected to each of the high-pressure heaters, the outlet of the intermediate-pressure cylinder is respectively connected to each of the third low-pressure heaters, and the outlet of the low-pressure cylinder is respectively connected to each of the second low-pressure heaters.

8. The coal-fired power station according to any one of claims 1-7, characterized in that, The other end of the fourth pipeline is further connected to the deaerator.

9. A power generation system, characterized in that, Comprising a molten salt energy storage module and a coal-fired power station according to any one of claims 1-8, the molten salt energy storage module includes a high-temperature molten salt tank, a low-temperature molten salt tank, a steam generation unit, and a molten salt heating unit. The molten salt heating unit is connected between the discharge port of the low-temperature molten salt tank and the feed port of the high-temperature molten salt tank, and the steam generation unit is connected between the discharge port of the high-temperature molten salt tank and the feed port of the low-temperature molten salt tank.

10. A running method, characterized in that, Applied to the coal-fired power station according to any one of claims 1-8, the operation method includes: When the coal-fired power station is in the first state and the sum of the loads of the coal-fired power station and the new energy power station is greater than the power transmission load: adjust the operation load of the boiler to be reduced to the lowest stable combustion load, and control the steam generated by the boiler to enter the molten salt heating unit of the molten salt energy storage power station through the first pipeline. The steam discharged from the molten salt heating unit enters the condenser through the second pipeline. When the coal-fired power station is in the first state and the sum of the loads of the coal-fired power station and the new energy power station is less than the power transmission load: increase the operation load of the boiler, and part of the steam-water mixture discharged from the deaerator enters the steam generation unit of the molten salt energy storage power station through the third pipeline. The steam discharged from the steam generation unit enters the steam turbine and the first heating unit respectively through the fourth pipeline. Wherein, the first state is that the boiler reaches the lowest stable combustion load, and all the steam discharged from the boiler enters the steam turbine.

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