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

Abstract

The application relates to the technical field of thermal power generation, in particular to a coal-fired power station based on molten salt heat storage, a power generation system and an operation method. The coal-fired power station 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 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 a pipeline between the boiler and the steam turbine, and the other end is connected to an air inlet of a molten salt heating unit. One end of the second pipeline is connected to an air outlet of the molten salt heating unit, and the other end is connected to the condenser. One end of the third pipeline is connected to the deaerator, and the other end is connected to an air inlet of a steam generation unit. One end of the fourth pipeline is connected to an air outlet of the steam generation unit, and the other end is connected to the steam turbine and the first heating unit respectively. The peak shaving depth and the variable load rate of the coal-fired power station are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal power generation, and in particular to a coal-fired power plant based on molten salt heat storage, a power generation system and an operation method. BACKGROUND

[0002] A wind-solar base refers to a large energy base in which multiple types of power sources such as wind power, photovoltaic power, thermal power, and energy storage facilities are simultaneously constructed, simultaneously connected to a power grid, jointly dispatched, and bundled for transmission. The thermal power in the base mainly plays a role in stabilizing the curve of new energy and adjusting peak and trough.

[0003] At present, a wind-solar base includes a coal-fired power plant and a new energy power plant, and the coal-fired power plant is coupled with the new energy power plant. When new energy resources are abundant, the load of the coal-fired power plant is controlled to be reduced; and when new energy resources are insufficient, the load of the coal-fired power plant is increased. Through flexible dispatching of the operation mode of the coal-fired power plant, the wind-solar base can stably supply power.

[0004] However, the depth of peak regulation of the coal-fired power plant is insufficient, which will lead to new energy curtailment when new energy resources are abundant, and the variable load rate of the coal-fired power plant is insufficient, which affects the stability of the power grid. SUMMARY

[0005] Therefore, the present application provides a coal-fired power plant based on molten salt heat storage, a power generation system and an operation method to solve the problem of insufficient depth of peak regulation of the coal-fired power plant and insufficient variable load rate of the coal-fired power plant in the related art.

[0006] In a first aspect, the present application provides a coal-fired power plant based on molten salt heat storage, the coal-fired power plant being coupled with a molten salt energy storage module and a new energy power plant, and the molten salt energy storage module being provided with a steam generation unit and a molten salt heating unit;

[0007] The coal-fired power plant includes a boiler, a steam turbine, a condenser, a deaerator, a first heating unit, a second heating unit and a generator, the steam turbine is connected with the boiler at an air inlet, the steam turbine is connected with the generator, the condenser is connected with the steam turbine at an air outlet, 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] 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 a pipeline between the boiler and the steam turbine, the other end of the first pipeline is connected with an air inlet of the molten salt heating unit; one end of the second pipeline is connected with an air outlet of the molten salt heating unit, and the other end of the second pipeline is connected with the condenser; one end of the third pipeline is connected with the deaerator, and the other end of the third pipeline 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 of the fourth pipeline is connected with the steam turbine and the first heating unit, respectively.

[0009] In a possible implementation, the steam turbine comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder connected in sequence, the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are all configured to drive the generator to generate electricity, the intake of the high-pressure cylinder is connected with the boiler, the outlet of the high-pressure cylinder is connected with the boiler, and the intake of the medium-pressure cylinder is connected with the boiler.

[0010] In a possible implementation, the pipeline between the intake of the high-pressure cylinder and the boiler and the pipeline between the intake of the medium-pressure cylinder and the boiler are respectively connected with 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 with the other end of the fourth pipeline.

[0012] In a possible implementation, the other end of the fourth pipeline is connected with the intake of the medium-pressure cylinder.

[0013] In a possible implementation, the first heating unit comprises 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 with the first low-pressure heater.

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

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

[0016] In a second aspect, the application further provides a coal-fired power plant, comprising a molten salt energy storage module and the coal-fired power plant described above.

[0017] In a third aspect, the application further provides a method for operating a coal-fired power plant, applied to the coal-fired power plant described above, and the method comprises:

[0018] When the coal-fired power plant is in the first state and the sum of the load of the coal-fired power plant and the load of the new energy power plant is greater than the power transmission load: the operating load of the boiler is adjusted to decrease to the minimum stable combustion load, the steam generated by the boiler is controlled to enter the molten salt heating unit of the molten salt energy storage power plant through the first pipeline, and the steam discharged by 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 load of the coal-fired power plant and the load of the new energy power plant is less than the power transmission load: the operating load of the boiler is increased, part of the steam-water discharged by the deaerator enters the steam generation unit of the molten salt energy storage power plant through the third pipeline, and the steam discharged by the steam generation unit enters the steam turbine and the first heating unit through the fourth pipeline, respectively.

[0020] The first state is that the boiler is at the minimum stable combustion load, and the steam discharged by the boiler all enters the steam turbine.

[0021] The coal-fired power plant is coupled with a molten salt energy storage module and a new energy power plant. When the load of the new energy power plant is high, that is, the new energy resource is abundant, the load of the boiler can be reduced to the minimum stable combustion load, and the steam discharged by the boiler can be transported to the molten salt heating unit through the first pipeline. The steam discharged from the molten salt heating unit can be transported to the condenser through the second pipeline. The steam heats the molten salt, the molten salt energy storage module is in the energy storage mode, the steam turbine stops taking in steam, the load of the coal-fired power plant is reduced or the coal-fired power plant stops outputting, and the peak shaving depth of the coal-fired power plant is increased. When the load of the new energy power plant is low, that is, the new energy resource is insufficient, the load of the boiler is increased, the steam discharged by the boiler is transported to the steam turbine, and part of the steam-water discharged by the deaerator can be transported to the steam generation unit through the third pipeline. The molten salt energy storage module releases energy, and the steam discharged by the molten salt energy storage module is transported to the steam turbine and the first heating unit through the fourth pipeline. In this way, the steam discharged by the molten salt energy storage module can increase the climbing rate of the coal-fired power plant and the variable load rate of the coal-fired power plant. BRIEF DESCRIPTION OF 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 needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

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

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

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

[0026] Figure 4 a schematic diagram of a coal-fired power plant provided by an embodiment of the present application;

[0027] Figure 5 a schematic diagram of power output of a wind-solar base provided by an embodiment of the present application.

[0028] Explanation of reference signs:

[0029] 100 - coal-fired power plant; 110 - boiler; 120 - steam turbine; 121 - high-pressure cylinder; 122 - medium-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 DESCRIPTION

[0031] In order to make the purpose, 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 drawings of the preferred embodiments of the present application. In the drawings, the same or similar reference signs represent the same or similar components or components with the same or similar functions throughout. The described embodiments are some of the embodiments of the present application, not all the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making 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 explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or indirect connection through an intermediate medium, or internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] In the description of the present application, it needs to be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

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

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

[0036] In the prior art, a wind-solar base includes a coal-fired power plant and a new energy power plant, and the coal-fired power plant is coupled with the new energy power plant. When new energy resources are abundant, the load of the coal-fired power plant is controlled to be reduced; when new energy resources are insufficient, the load of the coal-fired power plant is increased. By flexibly scheduling the operation mode of the coal-fired power plant, the wind-solar base can stably supply power. However, as shown in Figure 1 and Figure 2 The load of the coal-fired power plant is limited by the minimum stable combustion load of its boiler, for example, the minimum stable combustion load of the boiler is 30% of its rated load, the load of the coal-fired power plant is peak-regulated to 30% of the rated load of the coal-fired power plant, and the peak-regulation depth of the coal-fired power plant is insufficient, which will cause new energy curtailment when new energy resources are abundant. The dispatching instruction of the existing wind-solar base is about 5% pe / min, the response rate of the coal-fired power plant is generally 1%-1.5% pe / min, and the wind-solar base also needs to set up an electrochemical energy storage device, which increases the cost of the wind-solar base.

[0037] After repeated thinking and verification, the inventor found that if the coal-fired power plant is coupled with a molten salt energy storage module and a new energy power plant respectively, four pipelines, i.e., a first pipeline, a second pipeline, a third pipeline and a fourth pipeline, are arranged between the coal-fired power plant and the molten salt energy storage module. When new energy resources are abundant, the load of the boiler of the coal-fired power plant can be controlled to be reduced to the minimum stable combustion load, the steam originally entering the steam turbine is led into the molten salt heating unit of the molten salt energy storage module through the first pipeline, and the steam discharged by the molten salt energy storage module is led into the condenser of the coal-fired power plant 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 plant is not limited by the minimum stable combustion load of the boiler, the peak shaving depth of the coal-fired power plant is improved, and more new energy power generation is connected to the grid. When new energy resources are insufficient, the load of the boiler can be increased, part of the steam-water discharged by the deaerator can be led into the steam generation unit through the third pipeline, and the steam discharged by the steam generation unit can be sent into the steam turbine and the first heating unit through the fourth pipeline. In this way, the steam discharged by the steam generation unit can improve the climbing rate of the coal-fired power plant, i.e., improve the variable load rate of the coal-fired power plant, which is beneficial to the power generation system to reduce the cost of electrochemical energy storage.

[0038] Therefore, the inventor designs a coal-fired power plant, a power generation system and an operation method based on molten salt heat storage. The coal-fired power plant is coupled with a molten salt energy storage module and a new energy power plant, and the molten salt energy storage module is provided with a steam generation unit and a molten salt heating unit. The coal-fired power plant is provided with a first pipeline, a second pipeline, a third pipeline and a fourth pipeline. The first pipeline is used for leading the steam discharged by the boiler of the coal-fired power plant into the molten salt heating unit. The second pipeline is used for leading the steam discharged by the molten salt heating unit into the condenser of the coal-fired power plant. The third pipeline is used for leading part of the steam-water discharged by the deaerator into the steam generation unit. The fourth pipeline is used for leading the steam discharged by the steam generation unit into 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, the steam turbine can stop or further reduce the intake, and the peak shaving depth of the coal-fired power plant is improved. The steam discharged by the steam generation unit can enter the coal-fired power plant through the fourth pipeline, and the variable load rate of the coal-fired power plant is improved.

[0039] The technical solutions of the coal-fired power plant, the power generation system and the 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] Reference Figures 3 to 5As shown, the coal-fired power plant 100 provided by the embodiment of the present application is coupled with the molten salt energy storage module 200 and the new energy power plant, and 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 comprises 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 steam turbine 120 is connected with the boiler 110, the steam turbine 120 is connected with the generator 170, the condenser 130 is connected with 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. 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 with the steam inlet of the molten salt heating unit 220. One end of the second pipeline 182 is connected with the steam outlet of the molten salt heating unit 220, and the other end of the second pipeline 182 is connected with the condenser 130. One end of the third pipeline 183 is connected with the deaerator 140, and the other end of the third pipeline 183 is connected with the steam inlet of the steam generation unit 210. One end of the fourth pipeline 184 is connected with the steam outlet of the steam generation unit 210, and the other end of the fourth pipeline 184 is connected with the steam turbine 120 and the first heating unit 150 respectively.

[0041] The load of the boiler 110 can be adjusted between the minimum stable combustion load and the rated load. In a possible implementation, a valve can be arranged on the pipeline between the boiler 110 and the steam turbine 120 and the first pipeline 181 respectively, and by controlling the two valves, the steam discharged from the boiler 110 can be controlled to enter the steam turbine 120 entirely, enter the molten salt heating unit 220 entirely via the first pipeline 181 or enter the steam turbine 120 partially and enter the molten salt heating unit 220 partially via the first pipeline 181. It can be understood that the steam entering the molten salt heating unit 220 can heat the molten salt flowing in the molten salt heating unit 220. It can be understood that the steam originally entering the steam turbine 120 enters the molten salt heating unit 220 through the first pipeline 181, which decouples the steam turbine 120 from the boiler 110, so that the generator 170 further reduces power generation or stops power generation, which helps to reduce the load of the coal-fired power plant 100.

[0042] For example, valves can be installed on the third pipeline 183 and the fourth pipeline 184 respectively. When part of the steam and 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 and water discharged from the deaerator 140, allowing the steam generation unit 210 to discharge steam. It is worth mentioning that the steam entering the turbine 120 through the fourth pipeline 184 can directly increase the load of the coal-fired power plant 100, thereby increasing 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 this embodiment, the coal-fired power plant 100 can reduce the load of boiler 110 to the minimum stable combustion load when the load of the new energy power plant is high, i.e., when new energy resources are abundant. Steam discharged from boiler 110 can be transported to molten salt heating unit 220 via the first pipeline 181. After being discharged from molten salt heating unit 220, steam can be transported to condenser 130 via the second pipeline 182. Molten salt is heated by steam; at this time, molten salt energy storage module 200 is in energy storage mode, such as... Figure 5 As shown, reducing or stopping the intake of steam turbine 120 reduces or stops the power generation of generator 170, thereby reducing or stopping the power generation of generator 170, and thus reducing the load of coal-fired power plant 100 or stopping its output, increasing the peak-shaving depth of coal-fired power plant 100. When the load of the new energy power plant is low, i.e., when new energy resources are insufficient, the load of boiler 110 is increased. The steam discharged from boiler 110 is sent to steam turbine 120. Part of the steam and water discharged from deaerator 140 can be sent to steam generation unit 210 through third pipeline 183. At this time, molten salt energy storage module 200 releases energy. The steam discharged from molten salt energy storage module 200 is sent to steam turbine 120 and first heating unit 150 through fourth pipeline 184. In this way, the steam discharged from molten salt energy storage module 200 can increase the ramp rate of coal-fired power plant 100 and increase the load change rate of coal-fired power plant 100.

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

[0045] Exemplarily, the high-pressure cylinder 121, the medium-pressure cylinder 122 and the low-pressure cylinder 123 are connected with a power shaft, and an output end of the power shaft is connected with the generator 170. Steam discharged from the boiler 110 can enter the high-pressure cylinder 121 and the medium-pressure cylinder 122 respectively, steam discharged from the high-pressure cylinder 121 can return to the boiler 110 for heating again, and steam discharged from the medium-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 medium-pressure cylinder 122 and the low-pressure cylinder 123 gradually decrease, and the energy of the steam discharged from the boiler 110 can be more fully utilized by the above-mentioned arrangement, thereby improving the energy utilization rate of the coal-fired power plant 100.

[0047] In a specific embodiment, as shown in Figure 3 and Figure 4 , the pipeline between the gas inlet of the high-pressure cylinder 121 and the boiler 110 and the pipeline between the gas inlet of the medium-pressure cylinder 122 and the boiler 110 are respectively connected with 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 on the pipeline between the gas inlet of the high-pressure cylinder 121 and the boiler 110, and the second branch pipe is connected on the pipeline between the gas inlet of the medium-pressure cylinder 122 and the boiler 110. Optionally, a valve can be arranged on each of the first branch pipe and the second branch pipe.

[0049] Through the above-mentioned arrangement, when new energy resources are abundant, the steam originally entering the steam turbine 120 can be partially or entirely introduced into 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 through the first branch pipe alone, extract the steam discharged from the boiler 110 through the second branch pipe alone, or extract the steam discharged from the boiler 110 through the first branch pipe and the second branch pipe simultaneously. When the load of the new energy power plant is not less than the power transmission load, the coal-fired power plant 100 can be stopped.

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

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

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

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

[0054] Through the above arrangement, the steam discharged from the steam generating unit 210 will not affect the action of the high-pressure cylinder 121, and it is ensured that the steam entering the turbine 120 from the steam generating unit 210 can reliably drive the turbine 120 to act, thereby reliably improving the load of the coal-fired power plant 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 pipe 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 enters the deaerator 140 after sequentially flowing through the first low-pressure heater 151, each second low-pressure heater 152, and each third low-pressure heater 153, and the condensed water is heated step by step through each low-pressure heater of the first heating unit 150. It can be understood that the temperature of the condensed water entering the first low-pressure heater 151 from the condenser 130 is lower than the temperature of the steam discharged from the steam generating unit 210. In the first low-pressure heater 151, the steam discharged from the steam generating unit 210 exchanges heat with the condensed water flowing out of the condenser 130 to heat the condensed water.

[0057] In this structure, the steam discharged from the steam generating unit 210 has a higher temperature than the condensate water flowing out of the condenser 130, i.e. the steam discharged from the steam generating unit 210 can reliably heat the condensate water flowing out of the condenser 130 for the first time, so as to improve the load lifting rate of the boiler 110.

[0058] Illustratively, 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 connected to each of the high-pressure heaters 161, the outlet of the intermediate-pressure cylinder 122 is connected to each of the third low-pressure heaters 153, and the outlet of the low-pressure cylinder 123 is connected to each of the second low-pressure heaters 152.

[0059] In this structure, the condensate water flowing out of the deaerator 140 flows through each of the high-pressure heaters 161 in sequence and then enters the boiler 110. It can be understood that the steam flowing out of the high-pressure cylinder 121 has a higher temperature than the steam flowing out of the intermediate-pressure cylinder 122, which in turn has a higher temperature than the steam flowing out of the low-pressure cylinder 123. The specific number of the second low-pressure heaters 152, the third low-pressure heaters 153, and the high-pressure heaters 161 is not limited in this embodiment, and can be set according to actual needs by those skilled in the art.

[0060] In a possible implementation, each of the high-pressure heaters 161 is provided with a drain, and the steam flowing out of the high-pressure cylinder 121 can flow out of the drain to the deaerator 140 after heat exchange with the condensate water in the high-pressure heater 161. Each of the low-pressure heaters is also provided with a drain, and the steam can flow out of the drain to the condenser 130 after heat exchange with the condensate water in the low-pressure heater.

[0061] In this structure, after the steam discharged from the steam generating unit 210 heats the condensate water for the first time, the steam flowing out of each cylinder of the steam turbine 120 is used to heat the condensate water in stages, so as to improve the energy utilization rate of the coal-fired power plant 100.

[0062] As shown in FIGS. 1, 2, and 3, the fourth pipeline 184 is connected to the outlet of the steam generating unit 210. Figure 3 and Figure 4 As shown in FIGS. 1, 2, and 3, the fourth pipeline 184 is connected to the outlet of the steam generating unit 210.

[0063] It can be understood that the steam discharged from the steam generating unit 210 can also remove oxygen in the condensate water in the deaerator 140 after entering the deaerator 140. In a specific implementation, the end of the fourth pipeline 184 away from the steam generating unit 210 is provided with four branches, and the four branches are 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, respectively.

[0064] Through the above arrangement, the oxygen in the condensed water can be removed by the steam discharged by the steam generation unit 210, so that the ramp-up rate of the boiler 110 can be further improved, and thus the ramp-up rate of the coal-fired power plant 100 can be further improved.

[0065] The coal-fired power plant provided in this embodiment has the following results compared with the data of the coal-fired power plant in the related art, as shown in Table 1.

[0066] Table 1

[0067]

[0068] As can be seen from Table 1, the coal-fired power plant provided in this embodiment has increased flexibility, and the electrochemical energy storage configured in the wind-solar base can be appropriately reduced, thereby reducing the investment of the wind-solar base. For example, the variable load rate of the coal-fired power plant can be increased from 1-1.5 pe / min to 3% pe / min, and at least 250,000 kilowatt-hours of electrochemical energy storage configured in the base is reduced.

[0069] In another aspect, the present application also provides a power generation system, which comprises the molten salt energy storage module 200 and the coal-fired power plant 100 described above. The molten salt energy storage module 200 comprises 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. 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. Illustratively, the molten salt heating unit 220 comprises a plurality of sequentially connected molten salt heating devices, and the steam generation unit 210 comprises 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, and the steam after heat exchange flows out through the second pipeline 182. The high-temperature molten salt formed after heat exchange is stored in the high-temperature molten salt tank 230. When the steam-water or condensed water discharged by 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 or condensed water, and the low-temperature molten salt formed after heat exchange is stored in the low-temperature molten salt tank 240. The steam formed after heat exchange of the steam-water or condensed water is discharged through the fourth pipeline 184.

[0071] The power generation system provided in the application can control the working mode of the coal-fired power station 100 and the molten salt energy storage module 200 according to the load of the new energy power station, can reduce the output of the coal-fired power station 100 or stop the output of the coal-fired power station 100 when the new energy resource is abundant, and can reduce the abandoned electricity of the new energy. When the new energy resource is insufficient, the molten salt energy storage module 200 releases energy, and the steam discharged from the molten salt energy storage module 200 can improve the variable load rate of the coal-fired power station 100, can reduce the electrochemical energy storage configured in the large wind-solar base, and saves the cost of the large wind-solar base.

[0072] The application further provides a coal-fired power station 100 operation method, which is applied to the coal-fired power station 100 described above, and the operation method comprises the following steps of:

[0073] when the coal-fired power station 100 is in the first state and the sum of the load of the coal-fired power station 100 and the load of the new energy power station is greater than the power transmission load, adjusting the operation load of the boiler 110 to reduce to the minimum stable combustion load, controlling 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, and controlling the steam discharged from the molten salt heating unit 220 to enter the condenser 130 through the second pipeline 182;

[0074] when the coal-fired power station 100 is in the first state and the sum of the load of the coal-fired power station 100 and the load of the new energy power station is less than the power transmission load, increasing the operation load of the boiler 110, controlling part of the steam-water discharged from the deaerator 140 to enter the steam generation unit 210 of the molten salt energy storage power station through the third pipeline 183, and controlling the steam discharged from the steam generation unit 210 to enter the steam turbine 120 and the first heating unit 150 through the fourth pipeline 184 respectively;

[0075] wherein the first state is that the boiler 110 is at the minimum stable combustion load, and the steam discharged from the boiler 110 all enters the steam turbine 120.

[0076] when the coal-fired power station 100 is in the first state and the sum of the load of the coal-fired power station 100 and the load of the new energy power station is greater than the power transmission load, it indicates that the new energy generation is more, i.e., the new energy resource is abundant. The steam originally entering the steam turbine 120 enters the molten salt heating unit 220 through the first pipeline 181, the structure between the steam turbine 120 and the boiler 110 is realized, the work of the steam turbine 120 is further reduced or stopped, and the abandoned electricity of the new energy is reduced.

[0077] when the coal-fired power station 100 is in the first state and the sum of the load of the coal-fired power station 100 and the load of the new energy power station is less than the power transmission load, it indicates that the new energy generation is less, i.e., the new energy resource is insufficient. The steam discharged from the steam generation unit 210 improves the climbing rate of the coal-fired power station 100, can reduce the electrochemical energy storage configured in the large wind-solar base, and saves the cost of the large wind-solar base.

[0078] The operation method provided by the embodiment can set the working mode of the coal-fired power plant 100 according to different needs, can reduce the abandoned electricity of new energy when the new energy resource is sufficient, and meanwhile, the molten salt energy storage module 200 can also improve the variable load rate of the coal-fired power plant 100, reduce the electrochemical energy storage configured by the large wind-solar base, and reduce the investment of the large wind-solar base.

[0079] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part 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 plant based on molten salt heat storage, characterized in that, The coal-fired power plant is coupled with a molten salt energy storage module and a new energy power plant respectively, and the molten salt energy storage module is provided with a steam generation unit and a molten salt heating unit; 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 steam turbine is connected with the boiler at an inlet, the steam turbine is connected with the generator, the condenser is connected with the steam turbine at an outlet, 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. 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 a pipeline between the boiler and the steam turbine, the other end of the first pipeline is connected with an inlet of the molten salt heating unit, one end of the second pipeline is connected with an outlet of the molten salt heating unit, the other end of the second pipeline is connected with the condenser, one end of the third pipeline is connected with the deaerator, the other end of the third pipeline is connected with an inlet of the steam generation unit, and one end of the fourth pipeline is connected with an outlet of the steam generation unit, and the other end of the fourth pipeline is connected with the steam turbine and the first heating unit respectively. The first heating unit comprises 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 with the first low-pressure heater. The other end of the fourth pipeline is further connected with the deaerator. When the coal-fired power plant is in the first state and the sum of the load of the coal-fired power plant and the load of the new energy power plant is greater than the power transmission load, the operating load of the boiler is adjusted to decrease to the minimum stable combustion load, the steam generated by the boiler is controlled to enter the molten salt heating unit of the molten salt energy storage power plant through the first pipeline, and the steam discharged by the molten salt heating unit enters the condenser through the second pipeline. When the coal-fired power plant is in the first state and the sum of the load of the coal-fired power plant and the load of the new energy power plant is less than the power transmission load, the operating load of the boiler is increased, part of the steam and water discharged by the deaerator enters the steam generation unit of the molten salt energy storage power plant through the third pipeline, and the steam discharged by the steam generation unit enters the steam turbine and the first heating unit through the fourth pipeline. The first state is that the boiler is at the minimum stable combustion load, and all the steam discharged by the boiler enters the steam turbine.

2. The coal-fired power plant of claim 1, wherein, The steam turbine comprises a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder connected in sequence, the high-pressure cylinder, the medium-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 with the boiler, the outlet of the high-pressure cylinder is connected with the boiler, and the inlet of the medium-pressure cylinder is connected with the boiler.

3. A coal-fired power plant according to claim 2, characterised in that, The pipeline between the air inlet of the high-pressure cylinder and the boiler and the pipeline between the air inlet of the intermediate-pressure cylinder and the boiler are connected with one end of the first pipeline respectively.

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

5. The coal-fired power plant of claim 2, wherein, The other end of the fourth pipeline is connected with the air inlet of the intermediate-pressure cylinder.

6. The coal-fired power plant of claim 2, wherein, The second heating unit comprises a plurality of high-pressure heaters connected in sequence, the air outlet of the high-pressure cylinder is connected with each of the high-pressure heaters, the air outlet of the intermediate-pressure cylinder is connected with each of the third low-pressure heaters, and the air outlet of the low-pressure cylinder is connected with each of the second low-pressure heaters.

7. A power generation system characterized by comprising: The coal-fired power plant comprises a molten salt energy storage module and the coal-fired power plant of any one of claims 1-6, the molten salt energy storage module comprises 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.

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