Fused salt heating method for integrated system before full-load test operation of tower type photo-thermal power station

Abstract

The invention relates to the field of tower-type photo-thermal power generation systems, and provides a fused salt heating method for an integrated system before full-load test operation of a tower-type photo-thermal power station. The heating method comprises the steps that a low-temperature fused salt pump pumps fused salt in a low-temperature fused salt storage tank into a heat absorber, the fused salt is heated through the heat absorber, whether the temperature of the heated fused salt is larger than a second temperature or not is judged, when the temperature of the fused salt is larger than the second temperature, the fused salt flows to a high-temperature fused salt storage tank, and when the temperature of the fused salt is smaller than the second temperature, the fused salt flows back to the low-temperature fused salt storage tank; the flow of the low-temperature molten salt pump is controlled, so that the temperature of the molten salt entering the high-temperature molten salt storage tank is increased to a third temperature; the high-temperature fused salt pump pumps the fused salt with the third temperature in the high-temperature fused salt storage tank into the steam generation system; and the fused salt passing through the steam generation system flows back to the low-temperature fused salt storage tank, is heated to a fourth temperature through the heat absorber, and flows to the high-temperature fused salt storage tank. According to the heating method provided by the embodiment of the invention, the thermal stress impact of the storage tank and the heat absorber can be reduced.

Description

Technical Field

[0001] This invention relates to the field of tower-type concentrated solar power (CSP) systems, and more particularly to a method for heating molten salt in an integrated system before full-load commissioning of a tower-type CSP power plant. Background Technology

[0002] Tower solar thermal power plants are a new type of project. One of the challenges has always been raising the temperature of molten salt to meet the conditions for full-load commissioning. The highest temperature of molten salt can reach 565℃. Such a high-temperature heat transfer medium cannot be directly raised from 290℃ to 565℃ using an integrated system because molten salt will decompose during the heating process, resulting in the generation of non-condensable gases and impurities. In addition, the thermal stress of storage tanks and heat absorber equipment must be taken into account. Summary of the Invention

[0003] To solve the above-mentioned technical problems, or at least partially solve them, the present invention provides a method for heating molten salt in an integrated system before full-load commissioning of a tower solar thermal power plant.

[0004] This application discloses a method for heating molten salt in an integrated system before full-load commissioning of a tower solar thermal power plant. The integrated system includes: a low-temperature molten salt storage tank, a low-temperature molten salt pump, a heat absorber, a high-temperature molten salt storage tank, a high-temperature molten salt pump, and a steam generation system connected in series; a salt-melting system connected to the low-temperature molten salt storage tank; a power generation system connected in parallel with the steam generation system; the output end of the heat absorber is connected to both the low-temperature molten salt storage tank and the high-temperature molten salt storage tank, respectively; a first valve is connected in series between the output end of the heat absorber and the low-temperature molten salt storage tank, and a second valve is connected in series between the heat absorber and the high-temperature molten salt tank; the high-temperature molten salt storage tank is equipped with a breather valve and a drain valve; the heating method includes: melting solid molten salt through the salt-melting system and then transporting it to the low-temperature molten salt storage tank for initial liquefaction. The molten salt temperature is set to a first temperature. The cryogenic molten salt pump pumps the molten salt in the cryogenic molten salt storage tank into the heat absorber. The molten salt is heated by the heat absorber. It is determined whether the temperature of the heated molten salt is greater than a second temperature. If the temperature of the molten salt is greater than the second temperature, it flows to the high-temperature molten salt storage tank. If the temperature of the molten salt is less than the second temperature, it flows back to the cryogenic molten salt storage tank. The flow rate of the cryogenic molten salt pump is controlled so that the temperature of the molten salt in the high-temperature molten salt storage tank rises to a third temperature, which is greater than the second temperature. The high-temperature molten salt pump pumps the molten salt at the third temperature in the high-temperature molten salt storage tank into the steam generation system. The molten salt flowing through the steam generation system returns to the cryogenic molten salt storage tank, is then heated to a fourth temperature by the heat absorber, and flows to the high-temperature molten salt storage tank. The fourth temperature is greater than the third temperature.

[0005] According to the heating method provided in the embodiments of this application, the temperature of the molten salt is raised to the fourth temperature through two cycles. Compared with raising the temperature of the molten salt to the fourth temperature in one cycle, the thermal stress impact on the storage tank and the heat absorber can be reduced, allowing the high-temperature molten salt storage tank and the heat absorber to have a temperature rise adaptation process, and finally reach the required temperature of the molten salt.

[0006] In one possible implementation of this application, the heating method further includes: the high-temperature molten salt pump pumping molten salt at a third temperature from the high-temperature molten salt storage tank into the steam generating system; the molten salt flowing through the steam generating system back to the low-temperature molten salt storage tank, and then being heated by the heat absorber before flowing back to the high-temperature molten salt storage tank, causing the temperature of the molten salt in the high-temperature molten salt storage tank to rise to a fifth temperature, which is lower than the fourth temperature; the high-temperature molten salt pump pumping molten salt at the fifth temperature from the high-temperature molten salt storage tank into the steam generating system; the molten salt flowing through the steam generating system back to the low-temperature molten salt storage tank, and then being heated by the heat absorber before flowing back to the high-temperature molten salt storage tank, causing the temperature of the molten salt in the high-temperature molten salt storage tank to rise to the fourth temperature.

[0007] In one possible implementation of this application, the heating method further includes: when the temperature of the molten salt heated by the absorber is greater than a second temperature and less than a third temperature, controlling the cryogenic molten salt pump to reduce the flow rate.

[0008] In one possible implementation of this application, the heating method further includes: controlling the flow rate of the cryogenic molten salt pump so that the temperature difference between two adjacent flows of molten salt into the high-temperature molten salt storage tank is less than a second preset difference.

[0009] In one possible implementation of this application, the second preset difference is less than or equal to 50°C.

[0010] In one possible implementation of this application, the heating method further includes: allowing the molten salt at a third temperature to stand in the high-temperature molten salt storage tank for one week, and opening the breather valve and the drain valve of the high-temperature molten salt storage tank.

[0011] In one possible implementation of this application, the heating method further includes: the high-temperature molten salt pump pumping molten salt at a third temperature from the high-temperature molten salt storage tank into the steam generation system to supply the power generation system with electricity.

[0012] In one possible implementation of this application, the heating method further includes: after two adjacent heating cycles, the temperature difference of the molten salt in the high-temperature molten salt storage tank is less than a first preset difference value.

[0013] In one possible implementation of this application, the heating method further includes: the first preset difference is less than or equal to 20°C.

[0014] In one possible implementation of this application, the heating method further includes: when the solar heat collected by the absorber is large enough to heat the molten salt to a second temperature, the first valve is closed and the second valve is opened, allowing the molten salt at a temperature higher than the second temperature to flow into the high-temperature molten salt storage tank. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0017] Figure 1 Schematic diagram of an integrated system provided for some embodiments of this application; Figure 2 Flowcharts of heating methods provided in some embodiments of this application; Figure 3 A flowchart illustrating a heating method provided for other embodiments of this application.

[0018] Figure label: 100. Integrated system; 110. Low-temperature molten salt storage tank; 120. Low-temperature molten salt pump; 121. First valve; 130. Heat absorber; 140. High-temperature molten salt storage tank; 141. Second valve; 142. Breather valve; 143. Drain valve; 150. High-temperature molten salt pump; 160. Steam generation system; 170. Salt dissolving system; 180. Power generation system. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0021] Tower solar thermal power plants are a new type of project. One of the challenges has always been raising the temperature of molten salt to meet the conditions for full-load commissioning. The highest temperature of molten salt can reach 565℃. Such a high-temperature heat transfer medium cannot be directly raised from 290℃ to 565℃ using a heat collection system because molten salt will decompose during the heating process, resulting in the generation of non-condensable gases and impurities. In addition, the thermal stress of storage tanks and heat absorber equipment must be taken into account.

[0022] To address the aforementioned technical issues, this application provides a method for heating the molten salt of an integrated system before full-load commissioning of a tower solar thermal power plant.

[0023] For details, please refer to Figure 1 First, we will introduce the integrated system 100 before the full-load commissioning of the tower solar thermal power plant. This system includes a cryogenic molten salt storage tank 110, a cryogenic molten salt pump 120, a heat absorber 130, a high-temperature molten salt storage tank 140, a high-temperature molten salt pump 150, and a steam generation system 160, which are connected in series to form a loop. The molten salt is connected between the connected devices through pipelines.

[0024] The output end of the heat absorber 130 is connected to the low-temperature molten salt storage tank 110 and the high-temperature molten salt storage tank 140 respectively. A first valve 121 is connected in series between the output end of the heat absorber 130 and the low-temperature molten salt storage tank 110, and a second valve 141 is connected in series between the heat absorber 130 and the high-temperature molten salt tank. The high-temperature molten salt storage tank 140 is equipped with a breather valve 142 and a drain valve 143.

[0025] The integrated system 100 also includes a salt dissolving system 170 and a power generation system 180. The salt dissolving system 170 is connected to the cryogenic molten salt storage tank 110, and the power generation system 180 is connected in parallel with the steam generation system 160.

[0026] It should be noted that the salt system 170 refers to heating solid molten salt (such as a mixture of nitrates) above its melting point to liquefy it for subsequent circulation through pipelines. The molten salt is a binary mixture with a composition of 60% NaNO3 + 40% KNO3.

[0027] Low-temperature molten salt storage tank 110 is used to store molten salt at relatively low temperatures (typically meeting the storage requirements for molten salt at temperatures ranging from 290°C to 385°C), while high-temperature molten salt storage tank 140 is used to store molten salt at relatively high temperatures (typically meeting the storage requirements for molten salt at temperatures ranging from 385°C to 565°C).

[0028] The receiver 130 refers to a system that focuses solar radiation energy onto its surface through a concentrating system (such as a heliostat field), absorbing and converting it into heat energy to heat the internal heat transfer medium (such as molten salt, heat transfer oil, or water / steam). For example, in a tower solar thermal power plant, the temperature of the receiver 130 can reach above 565°C, and the receiver 130 is equipped with a temperature detector.

[0029] The steam generation system 160 generates high-quality steam by exchanging heat between molten salt and water / steam, which then provides power to the power generation system 180.

[0030] The first valve 121 and the second valve 141 can be solenoid valves that can control the flow rate. The first valve 121 is used to control whether the molten salt medium in the outlet pipe of the heat absorber 130 flows to the low-temperature molten salt storage tank 110, and the second valve 141 is used to control whether the molten salt medium in the outlet pipe of the heat absorber 130 flows to the high-temperature molten salt storage tank 140.

[0031] The breather valve 142 can be installed at the upper end of the high-temperature molten salt storage tank 140, and the drain valve 143 can be installed at the lower end of the high-temperature molten salt storage tank 140. The non-condensable gas generated after the decomposition of molten salt in the high-temperature molten salt storage tank 140 is discharged through the breather valve 142 at the top, and the impurities generated after the decomposition of molten salt in the high-temperature molten salt storage tank 140 are discharged through the drain valve 143 at the bottom of the high-temperature molten salt storage tank 140.

[0032] The heating method is explained below; please refer to [link / reference]. Figures 1 to 3 Heating methods include: After being melted by the salt melting system 170, the solid molten salt is transported to the low-temperature molten salt storage tank 110. The initial liquefied molten salt temperature is set to the first temperature, which can be set to 280℃, 290℃, 300℃, etc. For ease of description, the first temperature will be 290℃ below.

[0033] The cryogenic molten salt pump 120 pumps the molten salt in the cryogenic molten salt storage tank 110 into the heat absorber 130. The molten salt is heated by the heat absorber 130. It is determined whether the temperature of the molten salt after heating is greater than a second temperature. If the temperature of the molten salt is greater than the second temperature, it flows to the high temperature molten salt storage tank 140. If the temperature of the molten salt is less than the second temperature, it flows back to the cryogenic molten salt storage tank 110.

[0034] The second temperature can be 350℃, 340℃, 360℃, etc. For ease of description, the second temperature in the following text will be explained using 350℃ as an example.

[0035] It is understandable that the absorber 130 absorbs and gathers solar heat on its surface to heat the molten salt. However, depending on the solar intensity and the cleanliness of the mirror field, the solar heat collected by the absorber 130 will vary, and the temperature of the molten salt entering the absorber 130 will be 290°C.

[0036] When the solar heat collected by the absorber 130 is insufficient to heat the molten salt to 350°C, the second valve 141 closes and the first valve 121 opens. The molten salt flowing out of the absorber 130 flows back to the low-temperature molten salt storage tank 110. Then, the low-temperature molten salt pump 120 pumps the molten salt in the low-temperature molten salt storage tank 110 back into the absorber 130 for secondary heating. The temperature of the molten salt after secondary heating by the absorber 130 is compared with 350°C. If the temperature is less than 350°C, it flows back to the low-temperature molten salt storage tank 110. This process is repeated three times by the absorber 130 until the temperature of the molten salt flowing out of the absorber 130 is greater than 350°C. At this point, the first valve 121 closes and the second valve 141 opens, allowing the molten salt with a temperature higher than 350°C to flow into the high-temperature molten salt storage tank 140.

[0037] When the solar heat collected by the absorber 130 is large enough to heat the molten salt to 350°C, the first valve 121 closes and the second valve 141 opens, allowing the molten salt above 350°C to flow into the high-temperature molten salt storage tank 140.

[0038] The flow rate of the cryogenic molten salt pump 120 is controlled so that the temperature of the molten salt in the high-temperature molten salt storage tank 140 rises to a third temperature, which is higher than the second temperature.

[0039] The third temperature can be 480℃, 470℃, 490℃, etc. For ease of description, the third temperature will be described as 480℃ in the following text.

[0040] The temperature of the molten salt flowing from the heat absorber 130 to the high-temperature molten salt storage tank 140 is greater than 350°C. In order to ensure that the temperature of the molten salt in the high-temperature molten salt storage tank 140 is maintained at 480°C, when the system determines that the solar heat collected by the heat absorber 130 can heat the temperature of the molten salt to between 350°C and 480°C, that is, greater than the second temperature and less than the third temperature, the flow rate of the molten salt in the heat absorber 130 can be reduced by controlling the low-temperature molten salt pump 120, thereby achieving the heating of a small flow of molten salt, so that it can be heated to 480°C.

[0041] Alternatively, a second control method can be adopted. When the flow rate of the cryogenic molten salt pump 120 is too low to raise the molten salt temperature to 480°C, the flow rate of a small portion of the molten salt with a temperature greater than 350°C but less than 480°C can be directed to the high-temperature molten salt storage tank 140. When the weather conditions are good, the heliostat is clean, and the solar heat absorbed by the absorber 130 can raise the molten salt temperature to above 480°C, the flow rate of the cryogenic molten salt pump 120 can be increased to ensure that the overall temperature of the molten salt in the high-temperature molten salt storage tank 140 can reach 480°C.

[0042] Among them, the flow rate of the cryogenic molten salt pump 120 is controlled so that the temperature difference between two adjacent flows of molten salt into the high-temperature molten salt storage tank 140 is less than a second preset difference value. The second difference value can be set to 50°C. In this way, the thermal stress impact on the high-temperature molten salt storage tank 140 under high temperature conditions can be reduced.

[0043] Furthermore, the molten salt at the third temperature is left to stand in the high-temperature molten salt storage tank 140 for one week. The breather valve 142 and the drain valve 143 of the high-temperature molten salt storage tank 140 are then opened to allow the non-condensable gases generated after the molten salt decomposes to be discharged through the breather valve 142 on the top of the high-temperature molten salt storage tank 140. In this way, the discharge of non-condensable gases can prevent them from flowing into the heat absorber 130, which would cause uneven heat absorption inside the heat absorber 130, uneven surface temperature of the heat absorber 130 tube wall, excessively high local temperature, and large local thermal stress in the heat absorber 130.

[0044] Impurities generated after the decomposition of molten salt are discharged through the drain valve 143 at the bottom of the high-temperature molten salt storage tank 140, which can prevent system blockage / wear, maintain heat transfer efficiency, and slow down the catalytic decomposition of molten salt and corrosion of equipment and pipelines.

[0045] The high-temperature molten salt pump 150 pumps molten salt at a third temperature from the high-temperature molten salt storage tank 140 into the steam generation system 160. Thus, the heat of the molten salt in the high-temperature molten salt storage tank 140 is converted into steam of a certain quality by the steam generation system 160, which can be used to generate electricity in the power generation system 180, realizing the utilization and storage of energy.

[0046] Molten salt flowing through steam generation system 160 returns to low-temperature molten salt storage tank 110, and is then heated to a fourth temperature by heat absorber 130 before flowing to high-temperature molten salt storage tank 140. The fourth temperature is higher than the third temperature.

[0047] The fourth temperature is the target temperature of the high-temperature molten salt storage tank 140. In specific implementation, the fourth temperature can be 565℃. The maximum temperature of the molten salt medium is set at 565℃, which is the required temperature of the molten salt when the entire tower solar thermal power plant is running at full load.

[0048] In this way, by raising the temperature of the molten salt to the fourth temperature through two cycles, compared with raising the temperature of the molten salt to the fourth temperature through one cycle, the thermal stress impact on the storage tank and the heat absorber 130 can be reduced, allowing the high-temperature molten salt storage tank 140 and the heat absorber 130 to have a temperature rise adaptation process, and finally reach the required temperature of the molten salt.

[0049] In embodiments of this application, the heating method further includes: The high-temperature molten salt pump 150 pumps molten salt at the third temperature from the high-temperature molten salt storage tank 140 into the steam generation system 160. The molten salt flowing through the steam generation system 160 returns to the low-temperature molten salt storage tank 110, and then flows to the high-temperature molten salt storage tank 140 after being heated by the heat absorber 130. This raises the temperature of the molten salt in the high-temperature molten salt storage tank 140 to the fifth temperature, which is lower than the fourth temperature. The high-temperature molten salt pump 150 then pumps molten salt at the fifth temperature from the high-temperature molten salt storage tank 140 into the steam generation system 160. The molten salt flowing through the steam generation system 160 returns to the low-temperature molten salt storage tank 110, and then flows to the high-temperature molten salt storage tank 140 after being heated by the heat absorber 130. This raises the temperature of the molten salt in the high-temperature molten salt storage tank 140 to the fourth temperature.

[0050] In other words, after one cycle, the temperature of the molten salt in the high-temperature molten salt storage tank 140 is the third temperature; after two cycles, the temperature of the molten salt in the high-temperature molten salt storage tank 140 is the fifth temperature; and after the third cycle, the temperature of the molten salt in the high-temperature molten salt storage tank 140 is the fourth temperature.

[0051] In this way, through three heating cycles, the temperature of the molten salt in the high-temperature molten salt storage tank 140 is gradually raised to the fourth temperature, further reducing the thermal stress impact on the high-temperature molten salt storage tank 140 and the heat absorber 130, allowing the high-temperature molten salt storage tank 140 and the heat absorber 130 to have a slow adaptation process of temperature rise.

[0052] In the specific implementation process, the temperature of the molten salt in the high-temperature molten salt storage tank 140 can be raised to the fourth temperature through multiple heating cycles.

[0053] Specifically, the temperature of the molten salt in the high-temperature molten salt storage tank 140 can be raised to the fourth temperature through four cycles, five cycles, six cycles, seven cycles, eight cycles, or nine cycles.

[0054] After two adjacent heating cycles, the temperature difference of the molten salt in the high-temperature molten salt storage tank 140 can be less than a first preset difference value, wherein the first preset difference value is greater than or equal to 5°C and less than or equal to 20°C.

[0055] Specifically, the first preset difference can be 5℃, 10℃, 15℃, or 20℃. The following explanation uses 10℃ as the first preset difference.

[0056] In the specific implementation process, the liquid molten salt medium is set to the same heating temperature every three days, successively from 490℃, 490℃, 490℃, 500℃, 500℃, 500℃, 510℃, 510℃, 510℃, 520℃, 520℃, 520℃, 530℃, 530℃, 530℃, 540℃, 540℃, 540℃, 550℃, 550℃, 560℃, 560℃, 560℃, to finally 565℃, 565℃, 565℃.

[0057] Setting the same heating temperature every three days, with each increase of 10°C, can further reduce the thermal stress impact on the storage tank and heat absorber 130, allowing the storage tank and heat absorber 130 to have a slow adaptation process of temperature rise.

[0058] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0059] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for heating molten salt in a tower type solar thermal power station integrated system before full load commissioning, characterized in that, The integrated system includes: The system consists of a cryogenic molten salt storage tank, a cryogenic molten salt pump, a heat absorber, a high-temperature molten salt storage tank, a high-temperature molten salt pump, and a steam generation system, connected in series to form a loop. A salt-dissolving system, which is connected to the low-temperature molten salt storage tank; A power generation system, wherein the power generation system is connected in parallel with the steam generation system; The output end of the heat absorber is connected to the low-temperature molten salt storage tank and the high-temperature molten salt storage tank respectively. A first valve is connected in series between the output end of the heat absorber and the low-temperature molten salt storage tank, and a second valve is connected in series between the heat absorber and the high-temperature molten salt tank. The high-temperature molten salt storage tank is equipped with a breather valve and a drain valve. The heating method includes: After being melted by the salt dissolving system, the solid molten salt is transported to the low-temperature molten salt storage tank, and the initial liquefied molten salt temperature is set to a first temperature. The cryogenic molten salt pump pumps the molten salt in the cryogenic molten salt storage tank into the heat absorber. The molten salt is heated by the heat absorber. It is determined whether the temperature of the molten salt after heating is greater than a second temperature. If the temperature of the molten salt is greater than the second temperature, it flows to the high-temperature molten salt storage tank. If the temperature of the molten salt is less than the second temperature, it flows back to the cryogenic molten salt storage tank. The flow rate of the cryogenic molten salt pump is controlled so that the temperature of the molten salt entering the high-temperature molten salt storage tank rises to a third temperature, which is higher than the second temperature. The high-temperature molten salt pump pumps molten salt at a third temperature from the high-temperature molten salt storage tank into the steam generation system; The molten salt flowing through the steam generation system returns to the low-temperature molten salt storage tank, and is then heated to a fourth temperature by the heat absorber before flowing to the high-temperature molten salt storage tank. The fourth temperature is higher than the third temperature.

2. The method according to claim 1, wherein the molten salt is heated to a temperature of 550-600°C. The heating method further includes: The high-temperature molten salt pump pumps molten salt at a third temperature from the high-temperature molten salt storage tank into the steam generation system; The molten salt flowing through the steam generation system returns to the low-temperature molten salt storage tank, and then is heated by the heat absorber before flowing to the high-temperature molten salt storage tank, causing the temperature of the molten salt in the high-temperature molten salt storage tank to rise to the fifth temperature, which is lower than the fourth temperature. The high-temperature molten salt pump pumps molten salt at a fifth temperature from the high-temperature molten salt storage tank into the steam generation system; The molten salt flowing through the steam generation system returns to the low-temperature molten salt storage tank, and then is heated by the heat absorber before flowing to the high-temperature molten salt storage tank, causing the temperature of the molten salt in the high-temperature molten salt storage tank to rise to the fourth temperature.

3. The method for molten salt heating of the integrated system before full-load commissioning of a tower solar thermal power plant according to claim 1, characterized in that, The heating method further includes: When the temperature of the molten salt heated by the absorber is greater than the second temperature but less than the third temperature, the flow rate of the cryogenic molten salt pump is reduced.

4. The method for molten salt heating of the integrated system before full-load commissioning of a tower solar thermal power plant according to claim 1, characterized in that, The heating method further includes: The flow rate of the cryogenic molten salt pump is controlled so that the temperature difference between two adjacent flows of molten salt into the high-temperature molten salt storage tank is less than a second preset difference value.

5. The method for molten salt heating of the integrated system before full-load commissioning of a tower solar thermal power plant according to claim 4, characterized in that, The second preset difference is less than or equal to 50°C.

6. The method for molten salt heating of the integrated system before full-load commissioning of a tower solar thermal power plant according to claim 1, characterized in that, The heating method further includes: The molten salt at the third temperature is left to stand in the high-temperature molten salt storage tank for one week, and then the breather valve and the drain valve of the high-temperature molten salt storage tank are opened.

7. The method for molten salt heating of the integrated system before full-load commissioning of a tower solar thermal power plant according to claim 1, characterized in that, The heating method further includes: The high-temperature molten salt pump pumps molten salt at a third temperature from the high-temperature molten salt storage tank into the steam generation system to power the power generation system.

8. The method for heating molten salt in the integrated system before full-load commissioning of a tower-type photovoltaic and thermal power plant according to claim 1, characterized in that, The heating method further includes: After two consecutive heating cycles, the temperature difference of the molten salt in the high-temperature molten salt storage tank is less than a first preset difference value.

9. The method for heating molten salt in the integrated system before full-load commissioning of a tower-type photovoltaic and thermal power plant according to claim 8, characterized in that, The heating method further includes: The first preset difference is less than or equal to 20°C.

10. The method for heating molten salt in the integrated system before full-load commissioning of a tower-type photovoltaic and thermal power plant according to claim 1, characterized in that, The heating method further includes: when the solar heat collected by the absorber is large enough to heat the molten salt to a second temperature, the first valve is closed and the second valve is opened, and the molten salt at a temperature higher than the second temperature flows into the high-temperature molten salt storage tank.

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