A method and apparatus for directly generating stable superheated steam

Abstract

The present invention discloses a method and an apparatus for directly generating stable superheated steam in a solar power station. The method for directly generating stable superheated steam includes a plurality of linear mirror arrays arranged according to a set layout; a heat absorber is provided at the focal line position of the linear mirror arrays, and the heat absorber includes an evaporation tube, a steam-water separator, and a superheating tube; the inlet of the evaporation tube is a water inlet, the outlet of the evaporation tube is connected to the inlet of the steam-water separator, and the outlet of the steam-water separator is connected to the inlet of the superheating tube; the steam separated by the steam-water separator enters the superheating tube to be superheated to form superheated steam, and the superheated steam enters a work-consuming device to do work; the steam production temperature of the superheating tube is adjusted by controlling the amount of steam generated by the evaporation tube. The method and apparatus for directly generating stable superheated steam in this application neither cause influence and damage to the equipment itself, nor simplify the system setting and save the costs of equipment and personnel.

Description

Technical Field

[0001] The present invention relates to solar thermal utilization technology, and particularly to a method and device for directly generating stable superheated steam. Background Art

[0002] In the technical route of solar thermal power generation, linear solar thermal power generation has applied the direct steam generation (DSG) technology using water directly as the heat exchange medium for many years. The device for generating steam using the DSG technology is a direct steam generation device, which includes an evaporation tube and a superheat tube. Its basic principle is that the heat exchange medium (water) absorbs solar energy during the process of flowing through the evaporation tube, heats up to form water vapor, and then this water vapor enters the superheat tube to continue absorbing solar energy to generate superheated steam. The superheated steam can be used to drive a steam turbine to drive a generator set to generate electricity or be transported to other steam utilization devices for subsequent utilization.

[0003] A solar thermal power station generally consists of a solar island, a thermal energy storage island, and a conventional island. If the superheated steam generated by the solar island is unstable, the following problems may occur: 1) If the superheated steam generated by the solar island directly enters the steam turbine for power generation, the instability of the superheated steam will inevitably have an adverse impact on the life of the steam turbine and the quality of power generation; 2) If the superheated steam generated by the solar island enters the thermal energy storage island for thermal energy storage, when the steam parameters are too high, it will cause irreparable damage to the stability and life of the thermal energy storage island.

[0004] The utility model patent with the application number "201520843563.7" and the invention name "A direct steam generation device" discloses a direct steam generation device with an evaporation tube that can freely expand and contract, which effectively avoids the influence of elastic expansion and contraction on the structural stability of the evaporation tube. However, this application does not solve the key problem restricting the wide application of the DSG technology at present - how to directly produce stable superheated steam. In a serious over-temperature situation, it is likely to damage the entire system, and in a mild situation, it will also affect the life of the devices in the system. Generally, a water spray cooling method is used to cool the over-temperature superheated steam, but for a linear concentrating solar collector pipeline hundreds of meters long, the design of the water spray cooling device is relatively complex, lacking practicality, and the control effect is poor.

[0005] Obviously, finding a method for generating stable superheated steam directly in a linear concentrating solar thermal power station has become one of the urgent problems to be solved in the solar power generation industry. Summary of the Invention

[0006] The purpose of the present invention is to provide a simple, reliable, and convenient method for safely generating stable superheated steam, and a device corresponding to this method.

[0007] According to one aspect of the present invention, there is provided a method for directly generating stable superheated steam, including:

[0008] A plurality of linear mirror arrays arranged according to a set layout;

[0009] An absorber is arranged at the focal line position of the linear mirror array for receiving the sunlight converged by the linear mirror array and converting the light energy into heat energy. The absorber includes an evaporation tube, a steam-water separator, and a superheat tube, and the steam-water separator can separate the steam-water mixture;

[0010] The inlet of the evaporation tube is a water inlet, the outlet of the evaporation tube is connected to the inlet of the steam-water separator, and the outlet of the steam-water separator is connected to the inlet of the superheat tube;

[0011] After water enters the absorber, the steam separated by the steam-water separator enters the superheat tube to be superheated to form superheated steam, and the superheated steam is output to a work-consuming device to do work. The water separated by the steam-water separator re-enters the evaporation tube for circulation;

[0012] The steam temperature of the superheat tube is adjusted by controlling the amount of steam generated by the evaporation tube. When the amount of steam generated by the evaporation tube increases, the superheated steam temperature at the outlet of the superheat tube decreases; when the amount of steam generated by the evaporation tube decreases, the superheated steam temperature at the outlet of the superheat tube increases.

[0013] Further, the amount of steam generated by the evaporation tube is adjusted by adjusting the feed water flow rate at the inlet of the evaporation tube. The greater the feed water flow rate, the less the amount of steam generated by the evaporation tube; the smaller the feed water flow rate, the more the amount of steam generated by the evaporation tube.

[0014] Further, the amount of steam generated by the evaporation tube is adjusted by adjusting the feed water temperature at the inlet of the evaporation tube. The higher the feed water temperature at the inlet of the evaporation tube, the more the amount of steam generated by the evaporation tube; the lower the feed water temperature, the less the amount of steam generated by the evaporation tube.

[0015] When the superheated steam temperature at the outlet of the superheat tube is too high, the feed water flow rate at the inlet of the evaporation tube is reduced, the amount of steam generated by the evaporation tube is increased, and the feed water circulation ratio of the evaporation section is reduced; when the superheated steam temperature at the outlet of the superheat tube is too low, the feed water flow rate at the inlet of the evaporation tube is increased, and the amount of steam generated by the evaporation tube is reduced.

[0016] Further, when the superheated steam temperature at the outlet of the superheat tube is too high, the feed water temperature at the inlet of the evaporation section is increased by the heat of the work-consuming device, and the amount of steam generated by the evaporation tube is increased; when the superheated steam temperature at the outlet of the superheat tube is too low, the feed water temperature at the inlet of the evaporation section is reduced, and the amount of steam generated by the evaporation tube is reduced.

[0017] Furthermore, the feed water flow rate at the inlet of the evaporation tube is not less than the safe flow rate of the evaporation tube to prevent a series of problems such as pipe expansion caused by overheating of the evaporation tube due to too small a flow rate.

[0018] Furthermore, the linear mirror array includes a plurality of columns of mirror strips, a first driving device and a second driving device for driving the mirror array to track the sun.

[0019] Furthermore, the first driving device drives the linear mirror array corresponding to the evaporation tube to track the sun; the second driving device drives the linear mirror array corresponding to the superheater tube to track the sun.

[0020] Furthermore, the second driving device drives the focal line of the linear mirror array to deviate from the superheater tube to avoid the risk of dry burning during the start-up process of the superheater tube or overheating during operation.

[0021] According to another aspect of the present invention, there is provided a device for directly generating stable superheated steam, including

[0022] a plurality of linear mirror arrays arranged according to a set layout;

[0023] a heat absorber provided at the focal line position of the linear mirror array;

[0024] the heat absorber includes an evaporation tube, a steam-water separator and a superheater tube;

[0025] An evaporation inner tube is further arranged inside the evaporation tube. One end of the evaporation inner tube close to the outlet of the evaporation tube forms a first closed end, and the other end of the evaporation inner tube forms a first opening, and the evaporation inner tube is communicated with the inside of the evaporation tube through the first opening;

[0026] The inlet of the evaporation tube is a water inlet, the outlet of the evaporation tube is connected to the inlet of the steam-water separator, and the outlet of the steam-water separator is connected to the inlet of the superheater tube.

[0027] Furthermore, the inlet of the evaporation tube is connected to a flow rate regulating device, and the flow rate regulating device is used to regulate the feed water volume at the inlet of the evaporation tube.

[0028] Furthermore, the linear mirror array includes a plurality of columns of mirror strips, a first driving device and a second driving device for driving the mirror array to track the sun.

[0029] Furthermore, the linear mirror array corresponding to the evaporation tube is connected to the first driving device, and the linear mirror array corresponding to the superheater tube is connected to the second driving device.

[0030] Further, it further includes a work-consuming device connected to the outlet of the heat absorber; a pipeline connecting the inlet of the heat absorber and the outlet of the work-consuming device.

[0031] Preferably, the linear mirror array is a Fresnel mirror array or a trough mirror array.

[0032] As can be seen from the above technical solutions, in this application, the conventional desuperheating method of spraying water to reduce temperature is abandoned for controlling the superheated steam temperature. Instead, the temperature of the superheated steam is adjusted by controlling the amount of steam generated in the evaporation section, which simplifies the complexity of the system. At the same time, a double-drive structure is adopted for a single linear mirror array to respectively control the mirrors corresponding to the evaporation tube and the superheat tube, which can effectively avoid dry burning of the superheat tube and also control the over-temperature of the hot steam, making the system safer and more controllable. Therefore, the method and device for directly generating stable superheated steam in this application not only cancel the original water spray desuperheating device, but also do not cause system safety problems caused by dry burning of the heat collecting tube or system over-temperature, and can safely and stably output superheated steam with design parameters, simplify the overall operation of the solar thermal power station, and save equipment costs and operating costs. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0034] Figure 1 FIG. is a flow chart of directly generating superheated steam in a solar power station shown according to a preferred embodiment of the present application;

[0035] Figure 2 FIG. is a flow chart of directly generating stable superheated steam in a solar power station shown according to a preferred embodiment;

[0036] Figure 3 FIG. is a schematic structural diagram of the device for directly generating stable superheated steam and a schematic diagram of the flow direction of the heat transfer medium during operation.

[0037] In the figure, 1 is a linear mirror array, 3 is an evaporation tube, 4 is a superheat tube, 5 is a steam-water separator, 71 is a first driving device, and 72 is a second driving device. Detailed Embodiments

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] The inventors of the present invention noticed that in a linear concentrating solar thermal power plant, due to factors such as the change in solar light density and cloud cover, it is difficult to control the quality of the superheated steam generated by the direct steam generation device. Over-temperature operation may cause damage or reduced lifespan of some equipment. The traditional method of cooling steam is to spray water for temperature reduction on the steam pipeline. However, installing a water spray temperature reduction device on a steam pipeline hundreds of meters long will make the system relatively complex and the operating cost relatively high. Based on the above situation, the inventors of the present invention proposed an idea to break through the existing mode of cooling the evaporation pipeline through a water spray temperature reduction device, and thus proposed a new method and equipment for directly generating stable superheated steam from solar energy.

[0040] The following will elaborate in detail on the method for directly generating stable superheated steam in a linear concentrating solar power plant proposed in this application.

[0041] Figure 1 For the flowchart of directly generating superheated steam in a solar power plant shown in a preferred embodiment of this application, as Figure 1 shown, it includes the following steps:

[0042] S101 Pump water into the heat absorber.

[0043] A number of linear mirror arrays arranged according to a set layout;

[0044] Preferably, the linear mirror array is a Fresnel mirror array or a trough mirror array;

[0045] The linear mirror array includes a number of columns of mirror strips, a first driving device and a second driving device for driving the mirror array to track the sun.

[0046] Set a heat absorber at the focal line position of the linear mirror array and pump water into the heat absorber.

[0047] S102 The heat absorber is used to receive the sunlight concentrated by the linear mirror array tracking the sun and convert the solar energy into heat energy. The heat absorber includes an evaporation tube, a steam-water separator and a superheat tube. The inlet of the evaporation tube is the water inlet, the outlet of the evaporation tube is connected to the inlet of the steam-water separator, and the outlet of the steam-water separator is connected to the inlet of the superheat tube; water flows through the evaporation tube, absorbs heat and the water temperature rises and evaporates, converting into a steam-water mixture.

[0048] The steam-water mixture in the evaporation tube described in S103 enters the steam-water separator, and the steam-water separator can separate the steam-water mixture.

[0049] S104 The steam separated by the steam-water separator enters the superheater tube for superheating.

[0050] S105 The steam production temperature of the superheater tube is adjusted by controlling the amount of steam generated in the evaporation tube.

[0051] S106 The heat absorber produces qualified superheated steam.

[0052] S107 The superheated steam is output to the work-consuming device to do work and release heat, and after cooling, it enters the heat absorber again for circulation.

[0053] The work-consuming devices in this embodiment include, but are not limited to, steam turbines in solar power plants, thermal equipment for heating, other power generation equipment, or heat storage systems, etc.

[0054] S108 The water separated by the steam-water separator enters the evaporation tube again for circulation.

[0055] Figure 2 It is a flow chart showing the direct generation of stable superheated steam in a solar power plant according to a preferred embodiment. As Figure 2 shown, the steps include:

[0056] S105 When the steam parameters at the outlet of the superheater tube are unqualified, the amount of steam at the outlet of the evaporation tube is adjusted to control the temperature of the superheated steam at the outlet of the superheater tube.

[0057] S231 When the temperature of the superheated steam at the outlet of the superheater tube is too high, the second driving device drives the focal line of the linear mirror array to deviate from the superheater tube, avoiding the risk of dry burning or overheating during the startup process or operation of the superheater tube.

[0058] It can be easily imagined that at the beginning of system startup, the water in the evaporation tube has not formed steam. At this time, only the first driving device is started to drive the linear mirror to converge sunlight, that is, the superheater tube has no sunlight irradiation and will not cause the problem of dry burning of the superheater tube; when there is a steam-water mixture in the evaporation tube, the second driving device is started to drive the linear mirror to converge sunlight, and at this time both the evaporation tube and the superheater tube are irradiated by the converged sunlight. Or during normal system operation, in order to respond to emergencies or when the steam temperature at the outlet of the superheater tube is uncontrollably overheated, the second driving device can be used to drive the focal line of the linear mirror array to deviate from the superheater tube to ensure the safety of system operation.

[0059] S211 Adjust the feed water flow

[0060] Adjust the feed water flow rate at the inlet of the evaporation tube to adjust the amount of steam generated by the evaporation tube;

[0061] S212 When the temperature of the superheated steam at the outlet of the superheater tube is on the high side, reduce the feed water flow rate at the inlet of the evaporation tube and increase the amount of steam generated by the evaporation tube to finally obtain qualified superheated steam.

[0062] It should be noted that the feed water flow rate at the inlet of the evaporation tube is not lower than the safety flow rate of the evaporation tube.

[0063] S213 When the temperature of the superheated steam at the outlet of the superheater tube is on the low side, increase the feed water flow rate at the inlet of the evaporation tube and reduce the amount of steam generated by the evaporation tube to finally obtain qualified superheated steam.

[0064] S221 Adjust the feed water temperature

[0065] Adjust the feed water temperature at the inlet of the evaporation tube to adjust the amount of steam generated by the evaporation tube.

[0066] S222 When the temperature of the superheated steam at the outlet of the superheater tube is on the high side, increase the feed water temperature at the inlet of the evaporation section by the heat of the work-consuming device and increase the amount of steam generated by the evaporation tube to finally obtain qualified superheated steam.

[0067] S223 When the temperature of the superheated steam at the outlet of the superheater tube is on the low side, reduce the feed water temperature at the inlet of the evaporation section to reduce the amount of steam generated by the evaporation tube to finally obtain qualified superheated steam.

[0068] Figure 3 It is a schematic diagram of the structure of the device for directly generating stable superheated steam and the flow direction of the heat transfer medium during operation. As Figure 3As shown in the figure, a device for directly generating stable superheated steam is characterized by comprising: a plurality of linear mirror arrays 1 arranged according to a set layout, where the linear mirror array 1 is a linear Fresnel mirror array or a trough mirror array, preferably a linear Fresnel mirror array; a heat absorber arranged at the focal line position of the linear mirror array 1; and used to convert the sunlight converged by the linear mirror array 1 into heat energy, which is carried away by the working medium water. The heat absorber includes an evaporation tube 3, a steam-water separator 5, and a superheat tube 4; the liquid water in the evaporation tube 3 absorbs heat and rises in temperature during the flow process, and undergoes a phase change to form a gas-liquid two-phase flow. An evaporation inner tube is also arranged inside the evaporation tube 3, and the evaporation inner tube is used to overcome the adverse phenomena such as the vibration of the gas-liquid two-phase flow in the evaporation tube 3, and plays a role in disturbing the flow. The evaporation inner tube is arranged coaxially with the evaporation tube 3, one end of the evaporation inner tube close to the outlet of the evaporation tube forms a first closed end, the other end of the evaporation inner tube forms a first opening, and the evaporation inner tube is connected to the inside of the evaporation tube 3 through the first opening; the inlet of the evaporation tube 3 is a water inlet, the outlet of the evaporation tube 3 is connected to the inlet of the steam-water separator 5, and the steam-water separator 5 is used to separate the gas-liquid two-phase flow output by the evaporation tube 3 into gas and liquid. The outlet of the steam-water separator 5 is connected to the inlet of the superheat tube 4. The inlet of the evaporation tube 3 is connected to a flow regulating device, and the flow regulating device is used to regulate the water supply amount at the inlet of the evaporation tube, so as to control the steam amount output by the evaporation tube 3.

[0069] The linear mirror array 1 includes a plurality of columns of mirror strips, a first driving device 72 for driving the mirror array to track the sun, and a second driving device 71. The linear mirror array corresponding to the evaporation tube 3 is connected to the first driving device 72, and the linear mirror array corresponding to the superheat tube 4 is connected to the second driving device 71. The device for directly generating stable superheated steam further includes a power-consuming device (such as a steam turbine system or a heat storage system) connected to the outlet of the heat absorber, and a pipeline connecting the inlet of the heat absorber and the outlet of the power-consuming device (such as a steam turbine system or a heat storage system).

[0070] When the device for directly generating stable superheated steam works, the flow process of the heat transfer medium is as follows: The low-temperature water is pumped into the evaporation tube 3 through a pump, the water flows and heats up and evaporates in the evaporation tube 3 to form a gas-liquid two-phase flow, which is transported to the steam-water separator 5 for steam-water separation, the separated steam enters the superheat tube 4 for superheating, and the separated water is transported to the inlet of the heat absorber for re-circulation. The superheated steam in the superheat tube 4 is output to the power-consuming device to do work, such as generating electricity by a steam turbine generator or storing heat in a heat storage system.

[0071] As can be seen from the above technical solutions, the present application controls the temperature at the outlet of the heat absorber by adjusting the amount of steam generated by the evaporation tube. Compared with the existing conventional spray desuperheating method, the setting of spray desuperheating is omitted, so the complexity of the system and system control is reduced; in addition, the present application can safely control the superheated steam with stable output parameters, increase the service life of the system device, reduce the replacement frequency of accessories and the control difficulty of the system, and save equipment costs and personnel costs. Therefore, the method and equipment for directly generating stable superheated steam in the present application neither affect nor damage the equipment itself, simplify the system setting, and save the costs of equipment and personnel.

[0072] The technical features disclosed above are not limited to the combinations with other features already disclosed. Those skilled in the art can also make other combinations among the technical features according to the purpose of the invention, subject to the achievement of the purpose of the present invention.

Claims

1. A method for directly generating stable superheated steam, characterized in that, Comprising: A number of linear mirror arrays arranged in a set layout, the linear mirror array including a number of columns of mirror strips, a first driving device and a second driving device for driving the linear mirror array to track the sun; A heat absorber is arranged at the focal line position of the linear mirror array, and the heat absorber includes an evaporation tube, a steam-water separator and a superheater tube; The inlet of the evaporation tube is a water inlet, the outlet of the evaporation tube is connected to the inlet of the steam-water separator, and the outlet of the steam-water separator is connected to the inlet of the superheater tube; Water enters the evaporation tube, the first driving device drives the linear mirror array corresponding to the evaporation tube to track the sun and reflects sunlight to the evaporation tube, and the second driving device drives the focal line of the linear mirror array to deviate from the superheater tube to avoid dry burning of the superheater tube during startup; When there is a steam-water mixture in the evaporation tube, the steam separated by the steam-water separator enters the superheater tube, the second driving device drives the linear mirror array corresponding to the superheater tube to track the sun and reflects sunlight to the superheater tube, superheating is carried out in the superheater tube to form superheated steam, the superheated steam is output to a power-consuming device to do work, and the water separated by the steam-water separator re-enters the evaporation tube for circulation; The steam production temperature of the superheater tube is adjusted by controlling the steam quantity generated by the evaporation tube.

2. A method for directly generating stable superheated steam according to claim 1, characterized in that, The feed water flow rate at the inlet of the evaporation tube is adjusted to adjust the steam quantity generated by the evaporation tube.

3. A method for directly generating stable superheated steam according to claim 1, characterized in that, The feed water temperature at the inlet of the evaporation tube is adjusted to adjust the steam quantity generated by the evaporation tube.

4. A method for directly generating stable superheated steam according to claim 2, characterized in that, When the temperature of the superheated steam at the outlet of the superheater tube is on the high side, reduce the feed water flow rate at the inlet of the evaporation tube, reduce the feed water circulation ratio of the evaporation tube, and increase the steam quantity generated by the evaporation tube; when the temperature of the superheated steam at the outlet of the superheater tube is on the low side, increase the feed water flow rate at the inlet of the evaporation tube and reduce the steam quantity generated by the evaporation tube.

5. A method for directly generating stable superheated steam according to claim 3, characterized in that When the temperature of the superheated steam at the outlet of the superheater tube is on the high side, increase the feed water temperature at the inlet of the evaporation tube by the heat of the power-consuming device to increase the steam quantity generated by the evaporation tube; when the temperature of the superheated steam at the outlet of the superheater tube is on the low side, reduce the steam quantity generated by the evaporation tube by reducing the feed water temperature at the inlet of the evaporation tube.

6. A method for directly generating stable superheated steam according to claim 2, characterized in that The feed water flow rate at the inlet of the evaporation tube is not less than the safe flow rate of the evaporation tube.

7. A method for directly generating stable superheated steam according to claim 1, characterized in that, The first driving device drives the linear mirror array corresponding to the evaporation tube to track the sun; the second driving device drives the linear mirror array corresponding to the superheater tube to track the sun.

8. A method for directly generating stable superheated steam according to claim 1, characterized in that, The second driving device drives the focal line of the linear mirror array to deviate from the superheater tube to avoid the risk of overheating during the operation of the superheater tube.

9. A method for directly generating stable superheated steam according to claim 1, characterized in that, The linear mirror array is a Fresnel mirror array or a trough mirror array.

10. An apparatus for directly generating stable superheated steam, characterized in that, Comprising: A number of linear mirror arrays arranged in a set layout, the linear mirror array including a number of columns of mirror strips, a first driving device and a second driving device for driving the linear mirror array to track the sun, and the second driving device drives the focal line of the linear mirror array to deviate from the superheater tube during the startup of the superheater tube to avoid dry burning of the superheater tube during startup; The heat absorber is arranged at the focal line position of the linear mirror array; The heat absorber includes an evaporation tube, a steam-water separator and a superheater tube; An evaporation inner tube is further arranged inside the evaporation tube. One end of the evaporation inner tube close to the outlet of the evaporation tube forms a first closed end, and the other end of the evaporation inner tube forms a first opening. And the evaporation inner tube is communicated with the inside of the evaporation tube through the first opening; The inlet of the evaporation tube is a water inlet, the outlet of the evaporation tube is connected to the inlet of the steam-water separator, and the outlet of the steam-water separator is connected to the inlet of the superheater tube; The linear mirror array corresponding to the evaporation tube is connected to the first driving device. When water enters the evaporation tube, the first driving device drives the linear mirror array corresponding to the evaporation tube to reflect sunlight to the evaporation tube; the linear mirror array corresponding to the superheater tube is connected to the second driving device. When steam enters the superheater tube, the second driving device drives the linear mirror array corresponding to the superheater tube to reflect sunlight to the superheater tube.

11. An apparatus for directly generating stable superheated steam according to claim 10, characterized in that, The inlet of the evaporation tube is connected to a flow regulating device.

12. An apparatus for directly generating stable superheated steam according to claim 10, characterized in that, It further includes a power-consuming device connected to the outlet of the heat absorber; a pipeline connecting the inlet of the heat absorber and the power-consuming device.

13. An apparatus for directly generating stable superheated steam according to claim 10, characterized in that, The linear mirror array is a Fresnel mirror array or a trough mirror array.

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