A deep peak-shaving solar-assisted coal-fired power generation system and control method thereof

Abstract

The present invention discloses a deep peak-shaving solar-assisted coal-fired power generation system and a control method thereof, comprising a photothermal subsystem and a coal-fired power generation system, wherein the photothermal subsystem comprises a solar thermal collector, an oil-salt heat exchanger, a cold molten salt tank, a hot molten salt tank, an oil storage tank, a brine heat exchanger and an oil-water heat exchanger; the feed water of the boiler in the coal-fired power generation system is heated by the oil-water heat exchanger; the brine heat exchanger can utilize part of the steam extraction in the steam turbine for heat storage, thereby performing deep peak-shaving; the oil-salt heat exchanger is used to store heat in the molten salt, or the heat in the molten salt is released to heat the feed water of the boiler in the coal-fired power generation system through the oil-water heat exchanger. The deep peak-shaving solar-assisted coal-fired power generation system and the control method thereof of the present invention ensure that the photo-coal complementary power generation system participates in deep peak-shaving while outputting stably and safely.

Description

Technical Field

[0001] The present invention relates to the technical field of solar-coal complementary power generation systems, and in particular to a deep peak-shaving solar-assisted coal-fired power generation system and a control method thereof. Background Art

[0002] In the new energy utilization technology, deep coupling of solar thermal power generation and coal-fired power generation systems can share power and power generation equipment such as steam turbines, solving the problem of high initial investment in solar thermal power generation and improving the efficiency of solar thermal power generation; it can reduce the coal consumption of coal-fired units, significantly reduce fossil fuel consumption and carbon dioxide emissions, and also reduce the power generation load of coal-fired units to achieve flexible operation.

[0003] The photovoltaic-coal complementary power generation system, also known as the solar-assisted coal-fired power generation system, is a thermal system that is deeply coupled between the conventional coal-fired power generation system and the photovoltaic power generation system in the processes of photothermal conversion and heat-to-work conversion. By directly or indirectly introducing the solar heat collected by the collector field into the thermal power system, energy complementary utilization and clean coal-fired power generation are achieved. Among the existing photovoltaic-coal complementary power generation technologies, there are four types of solar side: trough type, tower type, dish type and linear Fresnel type, and the coupling with the coal-fired power generation system is also quite diverse.

[0004] Most of the existing photovoltaic-coal complementary power generation systems do not have a heat storage system on the solar side, so their output heat varies with the intensity of solar radiation and cannot be output stably. Although the coal-fired system can supplement the power changes on the solar side to a certain extent, it has a great impact on the overall stability and safety of the system; the system with heat storage often uses solar thermal and heat storage heat exchange, and the heat storage is then exchanged with a certain level of heat exchanger in the coal-fired power generation system. In this way, the efficiency of photovoltaic power generation is low, thus reducing the overall efficiency of the system. In addition, after the introduction of solar energy, a certain amount of peak-shaving pressure has been placed on the power grid. The existing photovoltaic-coal complementary power generation system is difficult to participate in deep peak-shaving while ensuring the stable and safe output of the system. Summary of the invention

[0005] The purpose of the present invention is to provide a deep peak-shaving solar-assisted coal-fired power generation system and a control method thereof to solve the problems existing in the above-mentioned prior art and ensure that the solar-coal complementary power generation system can participate in deep peak-shaving while achieving stable and safe output.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a deep peak-shaving solar-assisted coal-fired power generation system, comprising a photothermal subsystem and a coal-fired power generation system, wherein the photothermal subsystem comprises a solar thermal collector, an oil-salt heat exchanger, a cold molten salt tank, a hot molten salt tank, an oil storage tank, a brine heat exchanger and an oil-water heat exchanger; the oil outlet of the oil storage tank is connected to the oil inlet of the solar thermal collector, the oil outlet of the solar thermal collector is connected to the oil inlet of the oil-water heat exchanger through a first connecting pipe, the oil outlet of the oil-water heat exchanger is connected to the oil storage tank, and the oil-water heat exchanger is used to heat the feed water of the boiler in the coal-fired power generation system;

[0008] One end of the oil flow channel of the oil-salt heat exchanger is connected to the first connecting pipe, and the other end is connected to the oil storage tank. One end of the salt flow channel of the oil-salt heat exchanger is connected to the cold molten salt tank, and the other end is connected to the hot molten salt tank. The cold molten salt tank is connected to the inlet of the salt flow channel of the brine heat exchanger, and the hot molten salt tank is connected to the outlet of the salt flow channel of the brine heat exchanger; the extraction steam of the turbine in the coal-fired power generation system can be passed into the brine heat exchanger, and the outlet of the water flow channel of the brine heat exchanger is connected to the return water pipeline in the coal-fired power generation system for drainage.

[0009] Preferably, the solar thermal collector device is formed by connecting a plurality of trough-type solar thermal collector devices in series.

[0010] Preferably, the connecting pipe between the oil flow channel of the oil-salt heat exchanger and the first connecting pipe is a second connecting pipe, the first connecting pipe is provided with a first valve and a second valve, the interface between the second connecting pipe and the first connecting pipe is located between the first valve and the second valve, and the first valve is closer to the oil-water heat exchanger than the second valve, and the second connecting pipe is provided with a third valve; the third valve is a two-way valve, and the first valve and the second valve are both one-way valves.

[0011] Preferably, the coal-fired power generation system includes the steam turbine, the generator set, and a condenser, a condensate pump, a shaft seal heater, a deaerator, a feed water pump, a third high-pressure heat recovery heater, a second high-pressure heat recovery heater and a first high-pressure heat recovery heater which are connected in sequence by pipelines, the steam inlet of the condenser is connected to the steam outlet of the low-pressure cylinder of the steam turbine, the water outlet of the first high-pressure heat recovery heater is connected to the feed water inlet of the boiler, the first-stage extraction steam of the high-pressure cylinder of the steam turbine is passed into the first high-pressure heat recovery heater, the second-stage extraction steam of the high-pressure cylinder of the steam turbine is passed into the second high-pressure heat recovery heater, the extraction steam of the intermediate-pressure cylinder of the steam turbine is passed into the third high-pressure heat recovery heater, and four low-pressure heat recovery heaters are also connected in series between the shaft seal heater and the deaerator, and the extraction steam of the low-pressure cylinder is passed into the four low-pressure heat recovery heaters.

[0012] Preferably, the drain outlet of the first high-pressure regenerative heater is also communicated with the water inlet of the second high-pressure regenerative heater, and the drain outlet of the second high-pressure regenerative heater is communicated with the water inlet of the third high-pressure regenerative heater through a fourth connecting pipe.

[0013] Preferably, the inlet of the water flow channel of the brine heat exchanger is communicated with the steam outlet of the second-stage extraction steam of the high-pressure cylinder of the steam turbine through a third connecting pipe, and a fourth valve is arranged on the third connecting pipe; the outlet of the water flow channel of the brine heat exchanger is communicated with the fourth connecting pipe.

[0014] Preferably, the water outlet of the second high-pressure regenerative heater is communicated with the water inlet of the oil-water heat exchanger, and the water outlet of the oil-water heat exchanger is communicated with the water supply port of the boiler.

[0015] The present invention also provides a control method for the above-mentioned solar-assisted coal-fired power generation system for deep peak shaving, including the following steps:

[0016] S1: First, judge whether there is sunlight and whether deep peak shaving is required. If there is sunlight, go to step S2; otherwise, go to step S3. When the coal-fired power generation system needs to perform deep peak shaving, part of the extraction steam of the steam turbine in the coal-fired power generation system is introduced into the brine heat exchanger to heat the molten salt for heat storage, and after the extraction steam exchanges heat, it returns to the drain pipe of the coal-fired power generation system for draining. If deep peak shaving is not required, the water inlet of the brine heat exchanger is closed.

[0017] S2: Judge whether the heat Q1 collected by the solar heat collection device is greater than the heat Q2 required for heating the boiler feed water by the oil-water heat exchanger. If Q1>Q2, go to step S2-1; if Q1 = Q2, go to step S2-2; if Q1<Q2, go to step S2-3.

[0018] S2-1: The oil discharged from the solar heat collection device is simultaneously introduced into the oil-water heat exchanger and the oil-salt heat exchanger, and the feed water of the boiler in the coal-fired power generation system is heated through the oil-water heat exchanger, and the molten salt is heated through the oil-salt heat exchanger for heat storage.

[0019] S2-2: The oil discharged from the solar heat collection device is only introduced into the oil-water heat exchanger, and the feed water of the boiler in the coal-fired power generation system is heated through the oil-water heat exchanger.

[0020] S2-3: The oil discharged from the solar heat collection device is only introduced into the oil-salt heat exchanger, and the molten salt is heated through the oil-salt heat exchanger for heat storage.

[0021] S3: closing the oil outlet of the solar thermal collector, utilizing the heat stored in the molten salt in the hot molten salt tank to heat the oil in the oil storage tank through an oil-salt heat exchanger, and utilizing the heated oil to heat the feed water of the boiler in the coal-fired power generation system through an oil-water heat exchanger.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] The deep peak-shaving solar-assisted coal-fired power generation system and its control method of the present invention ensure that the light-coal complementary power generation system participates in deep peak-shaving while outputting stably and safely. The present invention adds molten salt heat storage and oil-salt heat exchangers on the photothermal side to "cut the peak and fill the valley" of the heat collected by the solar thermal collector, and achieves stable output through the control and conversion of the operating mode; by adding a brine heat exchanger, the heat storage system on the photothermal side plays a role not only on the photothermal side, but also in deep peak-shaving, storing excess heat, and at the same time, the deep peak-shaving process does not require redundant equipment and transformation, reducing the peak-shaving cost. The heat storage system composed of a cold molten salt tank, a hot molten salt tank, an oil-salt heat exchanger, a brine heat exchanger, etc. in the present invention can not only achieve a stable output of photothermal and coal-fired coupling, but also participate in the deep peak-shaving of coal-fired units, greatly improving the actual efficiency of the light-coal complementary system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a structural schematic diagram of the deep peak-shaving solar-assisted coal-fired power generation system of the present invention;

[0026] Among them: 100, deep peak-shaving solar-assisted coal-fired power generation system; 200, coal-fired power generation system; 300, solar thermal subsystem; 1, solar thermal collector; 2, oil storage tank; 3, oil-water heat exchanger; 4, oil-salt heat exchanger; 5, cold molten salt tank; 6, hot molten salt tank; 7, brine heat exchanger; 8, boiler; 9, high-pressure cylinder; 10, medium-pressure cylinder; 11, low-pressure cylinder; 12, generator; 13, condenser; 14, condensate pump; 15, shaft seal heater; 16, low-pressure heat recovery heater; 17, deaerator; 18, feed water pump; 19, third high-pressure heat recovery heater; 20, second high-pressure heat recovery heater; 21, first high-pressure heat recovery heater; 22, first valve; 23, second valve; 24, third valve; 25, fourth valve. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The purpose of the present invention is to provide a deep peak-shaving solar-assisted coal-fired power generation system and a control method thereof to solve the problems existing in the above-mentioned prior art and ensure that the solar-coal complementary power generation system can participate in deep peak-shaving while achieving stable and safe output.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 As shown: This embodiment provides a deep peak-shaving solar-assisted coal-fired power generation system 100, including a photothermal subsystem 300 and a coal-fired power generation system 200, the photothermal subsystem 300 includes a solar thermal collector 1, an oil-salt heat exchanger 4, a cold molten salt tank 5, a hot molten salt tank 6, an oil storage tank 2, a brine heat exchanger 7 and an oil-water heat exchanger 3; the oil outlet of the oil storage tank 2 is connected to the oil inlet of the solar thermal collector 1, the oil outlet of the solar thermal collector 1 is connected to the oil inlet of the oil-water heat exchanger 3 through a first connecting pipe, the oil outlet of the oil-water heat exchanger 3 is connected to the oil storage tank 2, and the oil-water heat exchanger 3 is used to heat the feed water of the boiler 8 in the coal-fired power generation system 200;

[0031] One end of the oil flow channel of the oil-salt heat exchanger 4 is connected to the first connecting pipe, and the other end is connected to the oil storage tank 2. One end of the salt flow channel of the oil-salt heat exchanger 4 is connected to the cold molten salt tank 5, and the other end is connected to the hot molten salt tank 6. The cold molten salt tank 5 is connected to the inlet of the salt flow channel of the brine heat exchanger 7, and the hot molten salt tank 6 is connected to the outlet of the salt flow channel of the brine heat exchanger 7; the extraction steam of the turbine in the coal-fired power generation system 200 can be passed into the brine heat exchanger 7, and the outlet of the water flow channel of the brine heat exchanger 7 is connected to the return water pipeline in the coal-fired power generation system 200 for drainage.

[0032] In this embodiment, the solar thermal collector 1 is formed by connecting a plurality of trough-type solar thermal collectors 1 in series. The connecting pipe between the oil flow channel of the oil-salt heat exchanger 4 and the first connecting pipe is the second connecting pipe, the first connecting pipe is provided with a first valve 22 and a second valve 23, the interface between the second connecting pipe and the first connecting pipe is located between the first valve 22 and the second valve 23, and the first valve 22 is closer to the oil-water heat exchanger 3 than the second valve 23, and the second connecting pipe is provided with a third valve 24; the third valve 24 is a two-way valve, and the first valve 22 and the second valve 23 are both one-way valves.

[0033] The coal-fired power generation system 200 includes a steam turbine, a generator 12 group and a condenser 13, a condensate pump 14, a shaft seal heater 15, a deaerator 17, a feed water pump 18, a third high-pressure heat recovery heater 19, a second high-pressure heat recovery heater 20 and a first high-pressure heat recovery heater 21 which are connected in sequence by pipelines. The steam inlet of the condenser 13 is connected to the steam outlet of the low-pressure cylinder 11 of the steam turbine, the water outlet of the first high-pressure heat recovery heater 21 is connected to the feed water inlet of the boiler 8, the first-stage extraction steam of the high-pressure cylinder 9 of the steam turbine is passed into the first high-pressure heat recovery heater 21, the second-stage extraction steam of the high-pressure cylinder 9 of the steam turbine is passed into the second high-pressure heat recovery heater 20, the extraction steam of the intermediate-pressure cylinder 10 of the steam turbine is passed into the third high-pressure heat recovery heater 19, and four low-pressure heat recovery heaters 16 are also connected in series between the shaft seal heater 15 and the deaerator 17, and the extraction steam of the low-pressure cylinder 11 is passed into the four low-pressure heat recovery heaters 16.

[0034] The drain outlet of the first high-pressure regenerative heater 21 is also connected to the water inlet of the second high-pressure regenerative heater 20, and the drain outlet of the second high-pressure regenerative heater 20 is connected to the water inlet of the third high-pressure regenerative heater 19 through a fourth connecting pipe.

[0035] The inlet of the water flow channel of the salt water heat exchanger 7 is connected to the steam outlet of the secondary extraction of the high-pressure cylinder 9 of the steam turbine through the third connecting pipe, and the third connecting pipe is provided with a fourth valve 25; the outlet of the water flow channel of the salt water heat exchanger 7 is connected to the fourth connecting pipe. The water outlet of the second high-pressure regenerative heater 20 is connected to the water inlet of the oil-water heat exchanger 3, and the water outlet of the oil-water heat exchanger 3 is connected to the water supply port of the boiler 8.

[0036] It should be noted that, in actual applications, there is no need to be limited to this embodiment, but the outlet of the water flow channel of the brine heat exchanger 7 must be connected to the steam outlet of the secondary extraction steam of the high-pressure cylinder 9 of the steam turbine. It is only necessary to allow part of the steam extraction of the steam turbine to pass through the brine heat exchanger 7 to heat the molten salt for heat storage and achieve the peak regulation purpose at the same time; similarly, there is no need for the oil-water heat exchanger 3 to be connected in parallel with the first high-pressure heat recovery heater 21 to replace the first high-pressure heat recovery heater 21 to assist in heating the feed water of the boiler 8. The specific pipeline connection settings can be appropriately adjusted as needed, and it is only necessary to use the oil-water heat exchanger 3 to assist in heating the feed water of the boiler 8.

[0037] This embodiment also provides a control method for the above-mentioned deep peak-shaving solar-assisted coal-fired power generation system 100, comprising the following steps:

[0038] S1: First, determine whether there is light and whether deep peak shaving is required. If there is light, proceed to step S2; otherwise, proceed to step S3. When the coal-fired power generation system 200 needs to perform deep peak shaving, part of the extraction steam of the steam turbine in the coal-fired power generation system 200 is introduced into the brine heat exchanger 7 to heat the molten salt for heat storage. After the extraction steam exchanges heat, it returns to the condensate return pipeline of the coal-fired power generation system 200 for draining. If deep peak shaving is not required, close the water inlet of the brine heat exchanger 7.

[0039] S2: Determine whether the heat Q1 collected by the solar collector 1 is greater than the heat Q2 required to heat the feed water of the boiler 8 by the oil-water heat exchanger 3. If Q1>Q2, proceed to step S2-1; if Q1 = Q2, proceed to step S2-2; if Q1<Q2, proceed to step S2-3.

[0040] S2-1: Simultaneously introduce the outlet oil of the solar collector 1 into the oil-water heat exchanger 3 and the oil-salt heat exchanger 4. Heat the feed water of the boiler 8 in the coal-fired power generation system 200 through the oil-water heat exchanger 3, and heat the molten salt for heat storage through the oil-salt heat exchanger 4.

[0041] S2-2: Only introduce the outlet oil of the solar collector 1 into the oil-water heat exchanger 3, and heat the feed water of the boiler 8 in the coal-fired power generation system 200 through the oil-water heat exchanger 3.

[0042] S2-3: Only introduce the outlet oil of the solar collector 1 into the oil-salt heat exchanger 4, and heat the molten salt for heat storage through the oil-salt heat exchanger 4.

[0043] S3: Close the outlet of the solar collector 1, utilize the heat storage of the molten salt in the hot molten salt tank 6, heat the oil in the oil storage tank 2 through the oil-salt heat exchanger 4, and utilize the heated oil to heat the feed water of the boiler 8 in the coal-fired power generation system 200 through the oil-water heat exchanger 3.

[0044] By configuring hot molten salt tanks with different capacities and switching between these different-capacity hot molten salt tanks, it can be ensured that during the day with sufficient sunlight, the overall system switches between step S2-1 and step S2-2, while at night, it operates in the state of step S3, and the light and heat output fluctuations caused by operating in step S2-3 should be avoided as much as possible.

[0045] In the description of the present invention, it should be noted that the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0046] The present specification uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A deep peak-shaving solar-assisted coal-fired power generation system, characterized in that: It comprises a photothermal subsystem and a coal-fired power generation system, wherein the photothermal subsystem comprises a solar thermal collector, an oil-salt heat exchanger, a cold molten salt tank, a hot molten salt tank, an oil storage tank, a brine heat exchanger and an oil-water heat exchanger; the oil outlet of the oil storage tank is connected to the oil inlet of the solar thermal collector, the oil outlet of the solar thermal collector is connected to the oil inlet of the oil-water heat exchanger through a first connecting pipe, the oil outlet of the oil-water heat exchanger is connected to the oil storage tank, and the oil-water heat exchanger is used to heat the feed water of the boiler in the coal-fired power generation system; One end of the oil flow channel of the oil-salt heat exchanger is connected to the first connecting pipe, and the other end is connected to the oil storage tank; one end of the salt flow channel of the oil-salt heat exchanger is connected to the cold molten salt tank, and the other end is connected to the hot molten salt tank; the cold molten salt tank is connected to the inlet of the salt flow channel of the brine heat exchanger, and the hot molten salt tank is connected to the outlet of the salt flow channel of the brine heat exchanger; the extraction steam of the steam turbine in the coal-fired power generation system can be passed into the brine heat exchanger, and the outlet of the water flow channel of the brine heat exchanger is connected to the return water pipeline in the coal-fired power generation system for drainage; The coal-fired power generation system comprises the steam turbine, the generator set and a condenser, a condensate pump, a shaft seal heater, a deaerator, a feed water pump, a third high-pressure heat recovery heater, a second high-pressure heat recovery heater and a first high-pressure heat recovery heater which are sequentially connected by pipelines, the steam inlet of the condenser is connected to the steam outlet of the low-pressure cylinder of the steam turbine, the water outlet of the first high-pressure heat recovery heater is connected to the feed water inlet of the boiler, the first-stage extraction steam of the high-pressure cylinder of the steam turbine is passed into the first high-pressure heat recovery heater, the second-stage extraction steam of the high-pressure cylinder of the steam turbine is passed into the second high-pressure heat recovery heater, the extraction steam of the intermediate-pressure cylinder of the steam turbine is passed into the third high-pressure heat recovery heater, and four low-pressure heat recovery heaters are connected in series between the shaft seal heater and the deaerator, and the extraction steam of the low-pressure cylinder is passed into the four low-pressure heat recovery heaters; The drain outlet of the first high-pressure regenerative heater is also connected to the water inlet of the second high-pressure regenerative heater, and the drain outlet of the second high-pressure regenerative heater is connected to the water inlet of the third high-pressure regenerative heater through a fourth connecting pipe; the inlet of the water flow channel of the brine heat exchanger is connected to the steam outlet of the secondary extraction of the high-pressure cylinder of the steam turbine through a third connecting pipe, and a fourth valve is provided on the third connecting pipe; the outlet of the water flow channel of the brine heat exchanger is connected to the fourth connecting pipe; The heat stored in the molten salt in the hot molten salt tank is used to heat the oil in the oil storage tank through an oil-salt heat exchanger, and the heated oil is used to heat the feed water of the boiler in the coal-fired power generation system through an oil-water heat exchanger.

2. The deep peak-shaving solar-assisted coal-fired power generation system according to claim 1 is characterized in that: The solar energy heat collection device is formed by connecting a plurality of trough type solar energy heat collection devices in series.

3. The deep peak-shaving solar-assisted coal-fired power generation system according to claim 1 is characterized in that: The connecting pipe between the oil flow channel of the oil-salt heat exchanger and the first connecting pipe is the second connecting pipe. A first valve and a second valve are arranged on the first connecting pipe. The interface between the second connecting pipe and the first connecting pipe is located between the first valve and the second valve, and the first valve is closer to the oil-water heat exchanger than the second valve. A third valve is arranged on the second connecting pipe; the third valve is a two-way valve, and both the first valve and the second valve are one-way valves.

4. The deep peak-shaving solar-assisted coal-fired power generation system according to claim 1 is characterized in that: The water outlet of the second high-pressure regenerative heater is communicated with the water inlet of the oil-water heat exchanger, and the water outlet of the oil-water heat exchanger is communicated with the feed water inlet of the boiler.

5. A control method for a deep peak-shaving solar-assisted coal-fired power generation system according to any one of claims 1 to 4, characterized in that: It includes the following steps: S1: First, judge whether there is sunlight and whether deep peak shaving is required. If there is sunlight, go to step S2; otherwise, go to step S3. When the coal-fired power generation system needs to perform deep peak shaving, part of the extraction steam of the steam turbine in the coal-fired power generation system is introduced into the salt-water heat exchanger to heat the molten salt for heat storage. After the extraction steam exchanges heat, it returns to the drain pipe of the coal-fired power generation system for draining. If deep peak shaving is not required, close the water inlet of the salt-water heat exchanger. S2: Judge whether the heat Q1 collected by the solar collector is greater than the heat Q2 required for the oil-water heat exchanger to heat the boiler feed water. If Q1>Q2, go to step S2-1; if Q1 = Q2, go to step S2-2; if Q1<Q2, go to step S2-3. S2-1: Simultaneously introduce the oil outlet of the solar collector into the oil-water heat exchanger and the oil-salt heat exchanger, heat the feed water of the boiler in the coal-fired power generation system through the oil-water heat exchanger, and heat the molten salt through the oil-salt heat exchanger for heat storage. S2-2: Only introduce the oil outlet of the solar collector into the oil-water heat exchanger, and heat the feed water of the boiler in the coal-fired power generation system through the oil-water heat exchanger. S2-3: Only introduce the oil outlet of the solar collector into the oil-salt heat exchanger, and heat the molten salt through the oil-salt heat exchanger for heat storage. S3: Close the oil outlet of the solar collector, utilize the heat storage of the molten salt in the hot molten salt tank, heat the oil liquid in the oil storage tank through the oil-salt heat exchanger, and utilize the heated oil liquid to heat the feed water of the boiler in the coal-fired power generation system through the oil-water heat exchanger.

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