Tower type photo-thermal steam production system based on water heat storage technology and control method

Abstract

The invention provides a tower type photo-thermal steam production system based on a water heat storage technology and a control method. The system comprises a heliostat field, a heat collection tower, a heat absorber and steam generation device, a steam pocket, a heat-preservation and pressure-resistant water storage tank and a pure water device, and the heliostat field is used for tracking direct sunlight rays and reflecting the rays to the surface of the heat absorber and steam generation device; the heat absorber and steam generation device comprises an internal high-pressure steam boiler and an external high-temperature-resistant metal sheet; a water inlet of the high-pressure steam boiler is communicated with the pure water device, and a steam outlet of the high-pressure steam boiler is connected with a steam inlet of the steam pocket; the high-pressure steam boiler is further provided with a saturated water outlet which is communicated with the water inlet of the water storage tank. When illumination is sufficient, part of saturated water of the boiler can be stored in the water storage tank for energy storage, when illumination is insufficient, the saturated water in the water storage tank can be injected into the boiler of the heat absorber, heat is supplemented, and the amount of prepared high-temperature and high-pressure steam is stable.

Description

Technical Field

[0001] This invention relates to the field of solar thermal steam generation technology, and in particular to a tower-type solar thermal steam generation system and control method based on water thermal storage technology. Background Technology

[0002] In recent years, tower-type solar thermal steam generation projects have been widely used. Tower-type solar thermal steam generation stations use heliostats to track the angle of solar incidence, reflecting sunlight onto the receiver of the collector tower to heat the receiver. The receiver heats the internal molten salt medium, and then a heat exchanger exchanges heat between the high-temperature molten salt and water to produce high-temperature, high-pressure steam. This system uses molten salt as a heat transfer and energy storage medium. Since the solidification temperature of molten salt is 220℃, far higher than the ambient temperature, solidification of the molten salt in the pipelines can cause equipment damage and lead to major accidents. The system requires extensive electric heat tracing and insulation / freezing protection measures, which increases system investment and makes the system's equipment and piping complex and inconvenient to maintain. Summary of the Invention

[0003] This invention addresses the problems existing in the prior art by providing a tower-type solar thermal steam generation system and control method based on water thermal storage technology. The system directly uses water as the heat conduction and storage medium, thereby avoiding the risk of condensation of the storage medium. The solar thermal system heats water to generate steam and can compensate for energy input fluctuations caused by solar eclipse due to clouds and fog through its own water energy storage system, thereby smoothing out steam output fluctuations.

[0004] To achieve the above technical objectives, this invention provides a tower-type solar thermal steam generation system based on water-based thermal storage technology, comprising a heliostat field and a solar collector tower, with the solar collector tower located in the center of the heliostat field. The system also includes a receiver / steam generator, a steam drum, an insulated and pressure-resistant water storage tank, and a pure water device. The receiver / steam generator is mounted on top of the solar collector tower. The heliostat field tracks direct sunlight and reflects the light onto the surface of the receiver / steam generator. The receiver / steam generator includes an internal high-pressure steam boiler and an external high-temperature resistant metal plate. The high-temperature resistant metal plate is directly connected to the high-pressure steam boiler and absorbs solar thermal energy, transferring it to the high-pressure steam boiler to heat water and generate high-pressure steam. The inlet of the high-pressure steam boiler is connected to a water supply pipe. The other end of the water supply pipe is connected to the pure water device. A pure water device outlet valve is installed at the outlet of the pure water device. A water supply pump is installed on the water supply pipe, and room temperature pure water is pumped into the high-pressure steam boiler through the water supply pump and the water supply pipe. The steam outlet of the high-pressure steam boiler is connected to a steam outlet pipe, and the other end of the steam outlet pipe is connected to the steam inlet of the steam drum. A saturated water outlet is also provided on the high-pressure steam boiler, and a saturated water return pipe is provided at the saturated water outlet. The other end of the saturated water return pipe is connected to the inlet of the water storage tank, so as to transport saturated hot water into the water storage tank for storage. An outlet pipe is provided at the bottom of the water storage tank, and the outlet pipe is connected to the water supply pipe. A saturated water outlet valve is installed at the saturated water outlet end of the high-pressure steam boiler, a water storage tank inlet valve is installed at the inlet of the water storage pipe, and a water storage tank outlet valve is provided at the outlet.

[0005] A preferred technical solution of the present invention: The system further includes a controller, wherein the saturated water outlet valve, the water storage tank inlet valve, the water storage tank outlet valve, and the pure water device outlet valve are all electric valves. The controller is connected to the saturated water outlet valve, the water storage tank inlet valve, the water storage tank outlet valve, the pure water device outlet valve, and the water pump via signals. The saturated water outlet valve electrically regulates the saturated water output of the high-pressure steam boiler, the water storage tank inlet valve electrically regulates the inlet flow of the water storage tank, the water storage tank outlet valve electrically regulates the outlet flow of the water storage tank, and the pure water device outlet valve electrically regulates the outlet flow of the pure water device.

[0006] The preferred technical solution of the present invention is as follows: the water supply pipe is connected in sequence to the pure water device, the water storage tank return pipe, the steam drum return pipe, the water supply pump and the high-pressure steam boiler in the direction of water flow.

[0007] The preferred technical solution of the present invention is as follows: the heliostat field is composed of multiple sets of reflectors with adjustable mirror angles, and the height of the heat collection tower is 190 to 210 meters.

[0008] The preferred technical solution of the present invention is that the water storage tank is a metal insulated and pressure-resistant tank with a volume greater than or equal to 100m³.

[0009] The preferred technical solution of the present invention is that the steam drum is a high-pressure metal insulated tank with a volume greater than or equal to 200m³.

[0010] The preferred technical solution of the present invention is that the pure water device is used to filter the salt in the water supply.

[0011] The preferred technical solution of the present invention is as follows: the bottom of the steam drum has a drain outlet, and a steam drum return water valve is installed at the drain outlet. The drain outlet of the steam drum is connected to the water supply pipe through a return water pipe. The steam drum return water valve is electrically regulated to adjust the steam drum return water volume. A steam output pipe is connected to the upper end of the steam drum. An electric auxiliary heating device is installed on the section of the steam output pipe located inside the steam drum, and a throttle valve is installed on the section of the steam output pipe located outside the steam drum. The steam drum is used to filter water to obtain dry steam and to buffer high-pressure steam. The controller is connected to the throttle valve and the electric auxiliary heating device respectively. The throttle valve is electrically regulated to adjust the steam output flow rate, and the electric auxiliary heating device is regulated to adjust the output steam temperature.

[0012] To achieve the above-mentioned technical objectives, this invention also provides a control method for a tower-type solar thermal steam generation system based on water thermal storage technology. The method involves a controller that adjusts the operation of the feedwater pump, saturated water outlet valve, water storage tank inlet valve, and water storage tank outlet valve according to environmental conditions and a specified logic, ensuring a stable output of high-pressure, high-temperature steam from the system. The specific control process is as follows:

[0013] When there is excess solar energy, the water supply pump, the pure water unit outlet valve, the saturated water outlet valve, and the storage tank inlet valve are activated. The absorber / steam generator absorbs the solar thermal energy reflected from the heliostat field, heating room-temperature water to produce high-pressure, high-temperature steam. Simultaneously, a portion of the heated saturated water is transferred to the storage tank for storage. The controller calculates the saturated water outlet flow rate from the absorber / steam generator to the storage tank. Normal temperature water supply flow rate during saturated water output process To ensure stable steam output; the ambient temperature feedwater flow rate during the saturated water output process. and saturated water effluent flow rate The calculation process is as follows:

[0014] Set a preset value for the ambient temperature feedwater flow rate during the saturated water output process. Then, calculate the preset value of saturated water outlet flow rate according to the following formula. :

[0015] ;

[0016] ;

[0017] ;

[0018] ;

[0019] ;

[0020] In the formula: Normal solar direct radiation, W / m²·s; The area of ​​the thermal collector mirror is 10,000 square meters. The heat collection efficiency of the heat collection field is % Thermal power of the collector field, kW; Specific enthalpy of water supply, kWh / t; Preset value of ambient temperature water supply flow rate during saturated water output process, kg / s; Water supply heat power, kW; Specific enthalpy of steam, kWh / t; Steam flow rate, kg / s; Steam heat load, kW; Enthalpy of saturated water, kWh / t; Preset saturated water outlet flow rate, kg / s; Saturated water outlet heat load, kW;

[0021] Calculated Substitute the following formula to verify whether it satisfies the condition. If the requirements are met, calculate the saturated water effluent flow rate. = , = If the requirements are not met, the normal temperature water flow rate will be reset and the above calculation process will be repeated until the requirements are met.

[0022] When sunlight is blocked by clouds, close the saturated water outlet valve and the water storage tank inlet valve, and open the feed water pump, the pure water unit outlet valve, and the water storage tank outlet valve. The water storage tank collects saturated water into the ambient temperature feed water, which is then pumped into the absorber / steam generator by the feed water pump. The controller calculates the saturated water inlet flow rate from the water storage tank to the absorber / steam generator. Normal temperature feedwater flow rate during saturated water input process To ensure stable steam output; the saturated water inlet flow rate Normal temperature feedwater flow rate during saturated water input process The calculation process is as follows:

[0023] Set a preset value for the water supply flow rate during saturated water input. Then, calculate the preset value of saturated water inlet flow rate according to the following formula. :

[0024] ;

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] In the formula: Normal solar direct radiation, W / m²·s; The area of ​​the thermal collector mirror is 10,000 square meters. The heat collection efficiency of the heat collection field is % Thermal power of the collector field, kW; Specific enthalpy of water supply, kWh / t; Preset flow rate of ambient temperature feedwater during saturated water input process, kg / s; Water supply heat power, kW; Specific enthalpy of steam, kWh / t; Steam flow rate, kg / s; Steam heat load, kW; Enthalpy of saturated water, kWh / t; Preset saturated water inlet flow rate, kg / s; Saturated water inlet heat load, kW;

[0030] Calculated Substitute the following formula to verify whether it satisfies the condition. If the requirements are met, calculate the saturated water effluent flow rate. = , = If the requirements are not met, the normal temperature water flow rate will be reset, and the above calculation process will be repeated until the requirements are met.

[0031] A further technical solution of the present invention: A steam output pipe is connected to the upper end of the steam drum; an electric auxiliary heating device is installed on the section of the steam output pipe located inside the steam drum, and a throttle valve is installed on the section of the steam output pipe located outside the steam drum; the controller is signal-connected to the throttle valve and the electric auxiliary heating device; when the normal solar radiation is less than a threshold, and the steam temperature at the outlet of the steam throttle valve decreases, the pure water device outlet valve is closed, the ambient temperature water supply is stopped, the water storage tank outlet valve is opened, and saturated water is pumped into the absorber / steam generator via the feed water pump, the electric auxiliary heating is activated, and steam is heated and output to ensure stable steam output; wherein, the minimum threshold for normal solar direct radiation... and electric auxiliary heating power Calculate using the following formula:

[0032] ;

[0033] ;

[0034] ;

[0035] ;

[0036] ;

[0037] ;

[0038] ;

[0039] In the formula: Thermal power of the collector field, kW; The collector power of the collector field when the normal direct solar radiation is at the minimum threshold, in kW; Steam heat load, kW; Saturated hydrothermal load, kW; Minimum threshold for normal direct solar radiation, W / m²·s; The area of ​​the thermal collector mirror is 10,000 square meters. The heat collection efficiency of the heat collection field is % Electric auxiliary heating power, kW.

[0040] In this invention, the heliostat field tracks direct sunlight and reflects it onto the surface of the solar collector tower's receiver. The receiver, which also functions as a steam generator, has an exterior of high-pressure resistant metal sheets and an interior of a high-pressure steam boiler. The external metal sheets absorb heat and transfer it to the internal boiler, heating water to produce high-temperature, high-pressure steam. When sunlight is abundant, a portion of the boiler's saturated water can be stored in a storage tank for energy storage. When sunlight is insufficient, the saturated water in the storage tank can be injected into the receiver's boiler to supplement heat, ensuring a stable output of high-temperature, high-pressure steam. This system reduces the need for molten salt thermal storage, simplifies the system, and improves its economic efficiency. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0042] Figure 2 This is a diagram of the external structure of the heat absorber / steam generator.

[0043] Figure 3 This is a diagram of the internal structure of the heat absorber and steam generator.

[0044] In the diagram: 1. Heliostat field; 2. Solar collector tower; 3. Absorber / steam generator; 31. High-temperature resistant metal sheet; 32. High-pressure steam boiler; 33. Saturated water outlet valve; 4. Steam drum; 41. Throttling valve; 42. Steam drum return valve; 5. Water storage tank; 51. Water storage tank inlet valve; 52. Water storage tank outlet valve; 6. Pure water device; 61. Pure water device outlet valve; 7. Feed water pump; 8. Feed water pipe; 9. Saturated water return pipe; 10. Steam outlet pipe; 11. Steam delivery pipe; 12. Controller. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 3 All accompanying drawings are simplified versions of embodiments and are intended only to clearly and concisely illustrate the embodiments of the present invention. The technical solutions shown in the drawings below are specific solutions of embodiments of the present invention and are not intended to limit the scope of the claimed invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0046] The embodiment provides a tower-type solar thermal steam generation system based on water thermal storage technology, such as Figures 1 to 3As shown, the system includes a heliostat field 1 and a solar collector tower 2, with the solar collector tower 2 located in the middle of the heliostat field 1. The system also includes a receiver / steam generator 3, a steam drum 4, an insulated and pressure-resistant water tank 5, a pure water device 6, and a controller 12. The receiver / steam generator 3 is mounted on top of the solar collector tower 2. The heliostat field 1 is used to track direct sunlight and reflect the light onto the surface of the receiver / steam generator 3. The receiver / steam generator 3 includes an internal high-pressure steam boiler 32 and an external high-temperature resistant metal plate 31. The high-temperature resistant metal plate 31 is directly connected to the high-pressure steam boiler 32 and is used to absorb solar thermal energy and conduct the heat to the high-pressure steam boiler 32 to heat water and generate high-pressure steam. The inlet of the high-pressure steam boiler 32 is connected to a water supply pipe 8, which is further connected to... One end is connected to the pure water device 6. A water supply pump 7 is installed on the water supply pipe 8. The water supply pump 7 and the water supply pipe 8 pump room temperature pure water into the high-pressure steam boiler 32. The steam outlet of the high-pressure steam boiler 32 is connected to a steam outlet pipe 10. The other end of the steam outlet pipe 10 is connected to the steam inlet of the steam drum 4. The high-pressure steam boiler 32 is also provided with a saturated water outlet and a saturated water return pipe 9. The other end of the saturated water return pipe 9 is connected to the inlet of the water storage tank 5. The saturated hot water is transported to the water storage tank 5 for storage. A water outlet pipe is provided at the bottom of the water storage tank 5. The water outlet pipe is connected to the water supply pipe 8. A saturated water outlet valve 33 is installed at the saturated water outlet end of the high-pressure steam boiler 32. A water storage tank inlet valve 51 is installed at the inlet of the water storage pipe 5. A water storage tank outlet valve 52 is provided at the outlet. The steam drum 4 has a drain outlet at its bottom, and a steam drum return water valve 42 is installed at the drain outlet. The drain outlet of the steam drum 4 is connected to the water supply pipe 8 through the return water pipe. The steam drum return water valve 42 is electrically adjustable to regulate the steam drum return water volume. The upper end of the steam drum 4 is connected to a steam output pipe 11. An electric auxiliary heating device 43 is installed on the inner section of the steam output pipe 11, and a throttle valve 41 is installed on the outer section of the steam output pipe 11. The steam drum 4 is used to filter water to obtain dry steam and also serves to buffer high-pressure steam.

[0047] In the embodiments, such as Figure 1 As shown, the water supply pipe 8 is connected sequentially to the pure water device 6, the water storage tank return pipe 5, the steam drum 4 return pipe, the water supply pump 7, and the high-pressure steam boiler 32, according to the water flow direction. The heliostat field 1 consists of multiple sets of adjustable mirrors. The height of the solar collector tower 2 is approximately 200 meters to facilitate receiving the sunlight focused by the heliostat field 1. The pure water device 6 is used to filter the salt in the water supply; the outlet of the pure water device 6 is equipped with a pure water device outlet valve 61. The water storage tank 5 is a 100m³ metal insulated and pressure-resistant tank. The steam drum 4 is a 200m³ high-pressure metal insulated tank.

[0048] In this embodiment, the saturated water outlet valve 33, the water storage tank inlet valve 51, the water storage tank outlet valve 52, the pure water device outlet valve 61, and the throttle valve 41 are all electric valves. The controller 12 is connected to the saturated water outlet valve 33, the water storage tank inlet valve 51, the water storage tank outlet valve 52, the throttle valve 41, the pure water device outlet valve 61, the water pump 7, and the electric auxiliary heating device 43 via signal connections. The saturated water outlet valve 33 electrically regulates the saturated water output of the high-pressure steam boiler 32; the water storage tank inlet valve 51 electrically regulates the inlet flow of the water storage tank 5; and the water storage tank outlet valve 52 electrically regulates the outlet flow of the water storage tank 5. The throttle valve 41 electrically regulates the steam output flow, and the electric auxiliary heating device 43 regulates the output steam temperature. The pure water device outlet valve 61 electrically regulates the outlet flow of the pure water device 6.

[0049] The controller regulates the operation of the feedwater pump, saturated water outlet valve, water storage tank inlet valve, and water storage tank outlet valve according to environmental conditions and specified logic, ensuring a stable output of high-pressure, high-temperature steam from the system. The specific control process is as follows:

[0050] In the embodiment, the initial state of the tower-type solar thermal steam generation system based on water thermal storage technology is as follows: saturated water outlet valve 33 is closed, steam drum return water valve 42 is closed, water storage tank inlet valve 51 is closed, water storage tank outlet valve 52 is closed, throttle valve 41 is closed, and water pump 7 is closed.

[0051] As the sun rises, the heliostat field 1 reflects direct sunlight into the heat absorber / steam generator 3. When the solar energy is moderate, the feed water pump 7, the pure water device outlet valve 61, and the throttle valve 41 are activated. The heat absorber / steam generator 3 absorbs the solar heat energy reflected by the heliostat field 1, heating room-temperature water to produce high-pressure, high-temperature steam. The steam is sent to the steam drum 4 through the steam outlet pipe 10, where it is dried and then sent to the steam outlet pipe 11 through the throttle valve 41. When there is a lot of water accumulated at the bottom of the steam drum 4, the steam drum return water valve 42 is opened, and the accumulated water flows into the feed water pipe 8 under the pressure of the air inside the steam drum 4. When all the accumulated water is forced out of the steam drum, the steam drum return water valve 42 is closed.

[0052] When there is excessive solar energy, the water pump 7, the saturated water outlet valve 33, and the water storage tank inlet valve 51 are activated. The absorber / steam generator 3 absorbs the solar thermal energy reflected by the heliostat field 1, heats room temperature water to produce high-pressure, high-temperature steam, and simultaneously delivers a portion of the heated saturated water to the water storage tank 5 for storage. The saturated water outlet flow rate of the absorber / steam generator 3 towards the water storage tank 5 is calculated. Normal temperature water supply flow rate during saturated water output process To ensure stable steam output; feedwater flow rate during saturated water output process. and saturated water effluent flow rate The calculation process is as follows:

[0053] Set a preset value for the ambient temperature feedwater flow rate during the saturated water output process. Then, calculate the preset value of saturated water outlet flow rate according to the following formula. :

[0054] ;

[0055] ;

[0056] ;

[0057] ;

[0058] ;

[0059] In the formula: Normal solar direct radiation, W / m²·s; The area of ​​the thermal collector mirror is 10,000 square meters. The heat collection efficiency of the heat collection field is % Thermal power of the collector field, kW; Specific enthalpy of water supply, kWh / t; Preset value of ambient temperature water supply flow rate during saturated water output process, kg / s; Water supply heat power, kW; Specific enthalpy of steam, kWh / t; Steam flow rate, kg / s; Steam heat load, kW; Enthalpy of saturated water, kWh / t; Preset saturated water outlet flow rate, kg / s; Saturated water outlet heat load, kW;

[0060] Calculated Substitute the following formula to verify whether it satisfies the condition. If the requirements are met, calculate the saturated water effluent flow rate. = , = If the requirements are not met, the normal temperature water flow rate will be reset and the above calculation process will be repeated until the requirements are met.

[0061] When sunlight is blocked by clouds, the saturated water outlet valve 33 and the water tank inlet valve 51 are closed, and the water tank outlet valve 52 is opened. The absorber / steam generator 3 absorbs the solar thermal energy reflected by the heliostat field 1 to heat the saturated water and generate high-pressure, high-temperature steam. The saturated water inlet flow rate from the water tank to the absorber / steam generator is calculated. Normal temperature feedwater flow rate during saturated water input process To ensure stable steam output; the saturated water inlet flow rate Water supply flow rate during saturated water input process The calculation process is as follows:

[0062] Set a preset value for the normal temperature feedwater flow rate during saturated water input. Then, calculate the preset value of saturated water inlet flow rate according to the following formula. :

[0063] ;

[0064] ;

[0065] ;

[0066] ;

[0067] ;

[0068] In the formula: Normal solar direct radiation, W / m²·s; The area of ​​the thermal collector mirror is 10,000 square meters. The heat collection efficiency of the heat collection field is % Thermal power of the collector field, kW; Specific enthalpy of water supply, kWh / t; Preset flow rate of ambient temperature feedwater during saturated water input process, kg / s; Water supply heat power, kW; Specific enthalpy of steam, kWh / t; Steam flow rate, kg / s; Steam heat load, kW; Enthalpy of saturated water, kWh / t; Preset saturated water inlet flow rate, kg / s; Saturated water inlet heat load, kW;

[0069] Calculated Substitute the following formula to verify whether it satisfies the condition. If the requirements are met, calculate the saturated water effluent flow rate. = , = If the requirements are not met, the normal temperature water flow rate will be reset, and the above calculation process will be repeated until the requirements are met.

[0070] When the normal solar radiation is less than the threshold, the steam temperature at the outlet of the steam throttle valve 41 decreases. The outlet valve of the pure water device 61 is then closed, stopping the ambient temperature water supply. The outlet valve of the storage tank is opened, and saturated water is pumped into the absorber / steam generator 3 via the feed water pump. The electric auxiliary heater 43 is then activated to heat and output steam, ensuring stable steam output. The minimum threshold for normal solar direct radiation is... and electric auxiliary heating power Calculate using the following formula:

[0071] ;

[0072] ;

[0073] ;

[0074] ;

[0075] ;

[0076] ;

[0077] ;

[0078] In the formula: Thermal power of the collector field, kW; The collector power of the collector field when the normal direct solar radiation is at the minimum threshold, in kW; Steam heat load, kW; Saturated hydrothermal load, kW; Minimum threshold for normal direct solar radiation, W / m²·s; The area of ​​the thermal collector mirror is 10,000 square meters. The heat collection efficiency of the heat collection field is % Electric auxiliary heating power, kW.

[0079] The invention will be further illustrated below with specific application examples. Taking a tower-type solar thermal steam generation system based on water thermal storage technology as an example, the initial system values ​​are as follows:

[0080] Area of ​​the heat collection mirror: =500,000 square meters;

[0081] Heat collection efficiency of the heat collection field: =35%;

[0082] Water supply quality: 15℃ / 0.1MPa;

[0083] Specific enthalpy of water supply: =17.5kWh / t;

[0084] Steam quality: 250℃ / 4MPa;

[0085] Specific enthalpy of steam: =777.78 kWh / t;

[0086] Steam flow rate: =16.67kg / s;

[0087] Saturated water quality: 250℃ / 4MPa;

[0088] Specific enthalpy of saturated water: =302.06kWh / t.

[0089] System initial state: saturated water outlet valve 33 is closed, steam drum return water valve 42 is closed, water storage tank inlet valve 51 is closed, water storage tank outlet valve 52 is closed, throttle valve 41 is closed, water supply pump 7 is closed, and pure water device outlet valve 61 is closed.

[0090] As the sun rises, the heliostat field 1 reflects direct sunlight onto the receiver / steam generator 3. The pure water system outlet valve 61, feedwater pump 7, and throttle valve 41 are opened. The pure water system 6 desalinates the ambient temperature feedwater, and the feedwater pump 7 pumps the ambient temperature feedwater into the receiver / steam generator 3. The ambient temperature feedwater is heated to produce steam, which enters the steam drum 4. The steam is dried inside the steam drum 4 and then output through the throttle valve 41.

[0091] When there is excess solar energy, the system's characteristic values ​​are as follows:

[0092] Normal solar direct radiation: =370W / ㎡·s.

[0093] Turn on the water supply pump 7, throttle valve 41, saturated water outlet valve 33, water storage tank inlet valve 51, and water storage device outlet valve 61. The heat absorber / steam generator 3 absorbs solar thermal energy reflected from the heliostat field 1 to heat room temperature water to produce high-pressure, high-temperature steam, while simultaneously transferring a portion of the saturated water to the water storage tank 5 for storage. When the water storage tank 5 is full of saturated water, close the saturated water outlet valve 33 and the water storage tank inlet valve 51 to stop storing saturated water.

[0094] The saturated water flow rate from the high-pressure steam boiler 32 to the water storage tank 5 and the ambient temperature water supply flow rate of water pump 7 The calculation process is as follows, where the preset value of the normal temperature water supply flow rate is... =35.34 kg / s;

[0095] ;

[0096] ;

[0097] ;

[0098] ;

[0099] ;

[0100] Calculated Substitute the following formulas to verify:

[0101] ;

[0102] It can be seen that the calculated If the stability requirement is met, then determine ; = =35.34kg / s.

[0103] When sunlight is blocked by clouds, the system's characteristic values ​​are as follows:

[0104] Normal solar direct radiation: =190W / ㎡·s.

[0105] Close the saturated water outlet valve 33 and the water storage tank inlet valve 51, and turn on the water supply pump 7, the water storage tank outlet valve 52, and the water storage device outlet valve 61. The absorber / steam generator 3 absorbs the solar thermal energy reflected by the heliostat field 1 to heat the saturated water and generate high-pressure, high-temperature steam. Simultaneously, the water storage tank 5 is controlled to supply stored saturated water towards the absorber / steam generator 3. The flow rate of saturated water supplied from the water storage tank towards the absorber / steam generator is calculated. Normal temperature feedwater flow rate during saturated water input process To ensure stable steam output; the saturated water inlet flow rate Normal temperature feedwater flow rate during saturated water input process The calculation process is as follows:

[0106] Set a preset value for the normal temperature feedwater flow rate during saturated water input. =4.59 kg / s, then calculate the preset value of saturated water inlet flow rate according to the following formula. :

[0107] ;

[0108] ;

[0109] ;

[0110] ;

[0111] ;

[0112] Calculated Substitute the following formulas to verify:

[0113] ;

[0114] It can be seen that the calculated If the stability requirement is met, then determine ,

[0115] = =4.59kg / s.

[0116] When the normal solar radiation is less than or equal to the threshold, the system characteristic values ​​are as follows:

[0117] Normal solar direct radiation: =150W / ㎡·s.

[0118] When the steam temperature at the outlet of steam throttle valve 41 decreases, the outlet valve of the pure water unit 61 is closed to stop the ambient temperature water supply. The outlet valve of the water storage tank is opened, and saturated water is pumped into the heat absorber / steam generator 3 through the feed water pump. The electric auxiliary heater 43 is turned on to heat and output steam. The calculation process for the minimum threshold of normal solar direct radiation and the electric auxiliary heating power is as follows.

[0119] ;

[0120] ;

[0121] ;

[0122] ;

[0123] ;

[0124] ;

[0125] .

[0126] The above description is merely one embodiment of the present invention, and while it is detailed and specific, it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A tower-based solar thermal steam generation system based on water thermal storage technology, comprising a heliostat field (1) and a thermal tower (2), said thermal tower (2) being located in the middle of the heliostat field (1), characterized in that: The system further comprises a heat absorber and steam generator (3), a steam drum (4), a heat-insulated and pressure-resistant water storage tank (5) and a pure water device (6), the heat absorber and steam generator (3) is erected on the top of the heat collection tower (2), the heliostat field (1) is used for tracking the direct sunlight and reflecting the sunlight to the surface of the heat absorber and steam generator (3); the heat absorber and steam generator (3) comprises an internal high-pressure steam boiler (32) and an external high-temperature resistant metal sheet (31), the high-temperature resistant metal sheet (31) is directly connected with the high-pressure steam boiler (32), the high-temperature resistant metal sheet (31) is used for absorbing the solar heat energy and conducting the heat energy to the high-pressure steam boiler (32) to heat water to prepare high-pressure steam; the water inlet of the high-pressure steam boiler (32) is connected with a water supply pipe (8), the other end of the water supply pipe (8) is communicated with the pure water device (6), a pure water device water outlet valve (61) is installed at the water outlet of the pure water device (6), a water supply pump (7) is arranged on the water supply pipe (8), normal-temperature pure water is pumped into the high-pressure steam boiler (32) through the water supply pump (7) and the water supply pipe (8), the steam outlet of the high-pressure steam boiler (32) is connected with a steam outlet pipe (10), the other end of the steam outlet pipe (10) is connected with the steam inlet of the steam drum (4); a saturated water outlet is further arranged on the high-pressure steam boiler (32), a saturated water return pipe (9) is arranged at the saturated water outlet, the other end of the saturated water return pipe (9) is communicated with the water inlet of the water storage tank (5), the saturated hot water is transported into the water storage tank (5) for storage, a water outlet pipe is arranged at the bottom of the water storage tank (5), the water outlet pipe is communicated with the water supply pipe (8), a saturated water outlet valve (33) is installed at the saturated water outlet end of the high-pressure steam boiler (32), a water storage tank water inlet valve (51) is installed at the water inlet of the water storage tank (5), and a water storage tank water outlet valve (52) is arranged at the water outlet.

2. A tower-based, thermal storage, thermal solar steam generation system according to claim 1, characterized in that: The system further comprises a controller (12), the saturated water outlet valve (33), the water storage tank water inlet valve (51), the water storage tank water outlet valve (52) and the pure water device water outlet valve (61) are all electric valves, the controller (12) is signal connected with the saturated water outlet valve (33), the water storage tank water inlet valve (51), the water storage tank water outlet valve (52), the pure water device water outlet valve (61) and the water pump (7) respectively, the saturated water outlet valve (33) is electrically adjusted to control the saturated water outlet quantity of the high-pressure steam boiler (32), the water storage tank water inlet valve (51) is electrically adjusted to control the water inlet flow of the water storage tank (5), the water storage tank water outlet valve (52) is electrically adjusted to control the water outlet flow of the water storage tank (5), and the pure water device water outlet valve (61) is electrically adjusted to control the water outlet flow of the pure water device (6).

3. A tower-based, thermal storage, thermal solar steam generation system according to claim 1 or 2, characterized in that: The water supply pipe (8) is connected with the pure water device (6), the water storage tank return pipe (5), the return pipe of the steam drum (4), the water supply pump (7) and the high-pressure steam boiler (32) in sequence according to the water flow direction.

4. A tower-based thermal system for steam generation using water as the heat storage medium as claimed in claim 1 or 2, wherein: The heliostat field (1) is composed of multiple sets of light mirrors with adjustable mirror angles, and the height of the heat collection tower (2) is 190-210 meters.

5. A tower-based, thermal storage, thermal solar steam generation system according to claim 1 or 2, characterized in that: The water storage tank (5) is a metal heat-insulated pressure tank with a volume greater than or equal to 100 m³.

6. A tower-based, thermal storage, thermal-to-steam system according to claim 1 or 2, wherein: The steam pocket (4) is a high-pressure metal heat-insulated tank with a volume greater than or equal to 200 m³.

7. A tower-based, thermal storage, thermal solar steam generation system according to claim 2, characterized in that: The pure water device (6) is used for filtering the salt in the water supply.

8. A tower-based thermal vapor generation system based on water thermal storage technology according to claim 2, characterized in that: The bottom of the steam pocket (4) is provided with a water outlet, and a steam pocket backwater valve (42) is installed on the water outlet. The water outlet of the steam pocket (4) is communicated with the water supply pipe (8) through a backwater pipe, and the steam pocket backwater valve (42) electrically adjusts the backwater amount of the steam pocket. The upper end of the steam pocket (4) is connected to a steam output pipe (11), and the steam output pipe (11) is provided with an electric auxiliary heating device (43) on the inner side pipe section in the steam pocket and a throttle valve (41) on the outer side pipe section of the steam output pipe (11). The steam pocket (4) is used for filtering water to obtain dry steam and plays a role in buffering high-pressure steam. A controller (12) is signal connected with the throttle valve (41) and the electric auxiliary heating device (43). The throttle valve (41) electrically adjusts the steam output flow, and the electric auxiliary heating device (43) adjusts the output steam temperature.

9. A control method of a tower type steam generation system based on water storage heat technology according to claim 2 or 8, characterized in that: Through the controller, the water supply pump, the saturated water outlet valve, the water storage tank inlet valve and the water storage tank outlet valve are controlled to work according to the specified logic according to the environmental conditions, so as to ensure that the system stably outputs high-pressure high-temperature steam. The specific control process is as follows: When solar energy is excessive, the water supply pump, the pure water device outlet valve, the saturated water outlet valve and the water storage tank inlet valve are opened, the heat absorber and steam generation device absorbs the solar heat energy reflected by the heliostat field, heats the normal temperature water to produce high pressure and high temperature steam, and at the same time, a part of the heated saturated water is transported to the water storage tank for storage. The controller calculates the saturated water outlet flow of the heat absorber and steam generation device towards the water storage tank and the normal temperature water flow during the saturated water output process , to ensure stable steam output; the normal temperature water flow and the saturated water outlet flow during the saturated water output process are calculated as follows: Setting a normal temperature feed water flow rate preset value in a saturated water output process Then, the saturated water output flow rate preset value is calculated according to the following equation : ； ； ； ； ； In the formula: Normal solar direct radiation, W / m2·s; Thermal field mirror area, 104m2; Thermal field thermal efficiency, %; Thermal field thermal power, kW; Feed water specific enthalpy value, kWh / t; Saturation water output process normal temperature feed water flow preset value, kg / s; Feed water thermal power, kW; Steam specific enthalpy value, kWh / t; Steam flow, kg / s; Steam thermal load, kW; Saturation water specific enthalpy value, kWh / t; Saturation water outlet flow preset value, kg / s; Saturation water outlet thermal load, kW; The calculated is substituted into the following formula to verify whether it meets the requirement ; if it meets the requirement, the calculated saturated water outflow = , = ; if it does not meet the requirement, the normal-temperature water supply flow is re-set, and the above calculation process is repeated again until the requirement is met; When the sunlight is blocked by clouds and fog, the saturated water outlet valve and the water storage tank inlet valve are closed, the water supply pump, the pure water device outlet valve and the water storage tank outlet valve are opened, the water storage tank will collect saturated water into the normal temperature water supply, which is pumped into the heat absorber and steam generating device through the water supply pump, and the controller calculates the saturated water inlet flow of the water storage tank to the heat absorber and steam generating device and the normal temperature water supply flow during the saturated water input process , to ensure the stability of the steam output; the saturated water inlet flow and the normal temperature water supply flow during the saturated water input process The calculation process is as follows: Setting a saturated water input process water flow rate preset value Then, the saturated water input flow rate preset value is calculated according to the following formula : ； ； ； ； ； In the formula: Normal solar direct radiation, W / m2·s; Thermal field mirror area, 104m2; Thermal field thermal efficiency, %; Thermal field thermal power, kW; Feed water specific enthalpy value, kWh / t; Saturation water input process temperature feed water flow rate preset value, kg / s; Feed water thermal power, kW; Steam specific enthalpy value, kWh / t; Steam flow rate, kg / s; Steam thermal load, kW; Saturation water specific enthalpy value, kWh / t; Saturation water inflow flow rate preset value, kg / s; Saturation water inflow thermal load, kW; The calculated is substituted into the following formula to verify whether it meets the requirement ; if it meets the requirement, the calculated saturated water outflow = , = ; if it does not meet the requirement, the normal temperature water supply flow is re-set, and the above calculation process is repeated again until the requirement is met.

10. The control method of a tower type solar steam generation system based on water thermal storage technology according to claim 9, characterized in that: The upper end of the steam drum is connected with a steam output pipe, the electric auxiliary heating device is installed in the inner pipe section of the steam output pipe in the steam drum, and the steam output pipe is provided with a throttle valve in the outer pipe section of the steam drum; the controller is signal connected with the throttle valve and the electric auxiliary heating device; when the normal solar radiation is less than the threshold value, the steam temperature at the outlet of the steam throttle valve is reduced, the water outlet valve of the pure water device is closed, the normal temperature feed water is stopped, the water outlet valve of the water storage tank is opened, the saturated water is pumped into the heat absorber and steam generator by the feed water pump, the electric auxiliary heating is started, the output steam is heated, and the stable steam output is ensured; wherein the minimum threshold value of the normal solar direct radiation and the electric auxiliary heating power The following formula is used for calculation: ； ； ； ； ； ； ； In the formula: Thermal power of the collector field, kW; Thermal power of the collector field corresponding to the minimum threshold of normal solar direct radiation, kW; Steam heat load, kW; Saturation water heat load, kW; Minimum threshold of normal solar direct radiation, W / ㎡·s; Mirror area of the collector field, 104㎡; Thermal efficiency of the collector field, %; Electric auxiliary heating power, kW.

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