Method for operating a solar thermal power plant, and solar thermal power plant

专利摘要:
A method for operating a solar thermal power plant (100) comprising multiple solar radiation receivers (1) operated using a molten salt as the heat transfer medium, wherein each solar radiation receiver (1) comprises a reflector device (3) and an absorber tube (5), comprises the following steps: - preheating of the absorber tubes (5), in the state in which said tubes are empty of the molten salt, to a temperature T by concentrating solar radiation on the absorber tubes (5) by means of the reflector devices (3), wherein the temperature T is greater than or equal to the melting temperature of the salt; after reaching the temperature T: - introduction of the molten salt into the absorber tubes (5) and recirculated conduction of the molten salt through the absorber tubes (5) while simultaneously repositioning the reflector devices (3) depending on the position of the sun; on ending the operation: -release of the molten salt out of the absorber tubes (5).
公开号:ES2620279A2
申请号:ES201690039
申请日:2015-02-05
公开日:2017-06-28
发明作者:Martín EICKHOFF
申请人:Deutsches Zentrum fuer Luft und Raumfahrt eV；
IPC主号:

专利说明:

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It can also be provided that during the preheating the secondary heat transfer medium is recirculated at a high pressure, for example up to 15 bars. This has the advantage of a lower pressure loss in the recirculation and a higher density of the secondary heat transfer medium, whereby the transmission behavior is improved
5 heat and heat transport capacity.
The invention further relates to a solar thermal power plant for operation with a molten salt as a heat transfer medium with several solar radiation receivers, which respectively have a reflector device and an absorber tube through which the heat transfer medium can be conducted. The solar thermal power plant according to the invention is characterized in that the absorber tubes are arranged with a slope in the direction of the at least one storage tank for the molten salt. In this way it is achieved that the molten salt used for the normal operation of the solar thermal power plant can be evacuated in a simple manner and manner from the absorber tubes, so that the molten salt is prevented from solidifying during a pause of operation. the solar thermal power plant in the absorber tubes. This prevents the need for laborious defrosting of molten salt during the new commissioning of the solar thermal power plant or laborious and cost-intensive heating of molten salt during the operating break. The slope allows advantageously that salt
20 melted reach the storage tank due to the force of gravity.
In the context of the invention, the feature "pending in the direction of the at least one storage tank" also comprises variants in which a lower end of the absorber tubes is also directed in a different direction than the storage tank 25, however, there is a tubular connection between the lower end of the absorber tube and the storage tank, through which the molten salt reaches the storage tanks. The direction of the slope is therefore the flow direction along the flow path in the direction of the storage tank. The absorber tubes may be arranged, for example, with a
30 angle α of up to 10º with respect to the horizontal.
It is preferably provided that the absorber tubes of several reflector devices are connected to each other forming a chain of absorber tubes and form a continuous slope. Consequently, a long branch of absorber tubes originates, through which the molten salt can be evacuated advantageously from the absorber tubes due to the continuous slope. For example, absorber tubes can
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of solar radiation, the molten salt being able to be heated, for example, from a temperature of 290 ° C to about 550 ° C.
The storage tank 11 and the hot salt tank 13 respectively have 5 a bag of nitrogen 15, whereby corrosion by air inclusions, as well as the aging of the molten salt, is avoided.
At the end of the operation of the solar thermal power plant 1, the molten salt of the absorber tubes 5 is evacuated and is taken to the storage tank 11. In this respect, the molten salt flows through the slope due to the force of gravity in the direction of the storage tank 11. In the exemplary embodiment shown, the molten salt flows in the opposite direction to the normal flow direction during the exit through the front solar radiation receivers 1 in the normal flow direction ( that is, the flow direction during normal operation) of the molten salt, while the
15 subsequent solar radiation receivers 1 in the normal flow direction are abandoned in the normal flow direction. The normal flow direction of the molten salt is represented by the arrows. The solar radiation receivers 1 in a loop 9 are therefore emptied of the molten salt accordingly very quickly, while the molten salt simultaneously flows out of the chains of parallel-arranged absorber tubes.
The absorber tubes 5 or chains of absorber tubes are preferably inclined at an angle α of 10 ° with respect to the horizontal.
The solar thermal power station 100 also has a power supply 17, which flows into the
25 transverse connection 7 at the upper end of the chains of absorber tubes. A secondary heat transfer medium can be conducted through the feed to the absorber tubes 5. The secondary heat transport medium can be, for example, nitrogen. In this regard, nitrogen from the nitrogen bag 15 of the storage tank 11 can be used. Preferably the secondary heat transfer medium is introduced into the
30 absorber tubes 5 during the evacuation of the molten salt. Since in the evacuation of the molten salt from the absorber tubes to the storage tank 11 the nitrogen is pushed from the nitrogen bag 15, it can be advantageously conducted through the feed 17 to the absorber tubes 5. In the supply 17 may be arranged, for example, a compressor or a pump, through which the
35 secondary heat transfer medium with high pressure in the absorber tubes 5. In this way the secondary heat transport medium can act to aid in the evacuation of the molten salt,
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while the secondary heat transfer medium presses the molten salt out of the absorber tubes 5.
In order to favor an evacuation, a pump 5 can also be used.
During the pause of operation of the solar thermal power plant, which is carried out, for example, at night or during periods of bad weather or for maintenance, the secondary heat transfer medium remains in the absorber tubes 5.
10 When the solar thermal power plant is put into operation, the secondary heat transfer medium is first conducted with recirculation through the solar radiation receivers 1. The reflector devices are focused on the absorber tubes 5 from the unfocused position adopted during the operating pause, in order to preheat these to
15 regular operation. Due to the recirculation of the secondary heat transfer medium, the heat is distributed relatively evenly in the absorber tubes 5, so that too high temperature gradients that could lead to deterioration of the absorber tubes 5 are avoided. Depending on the intensity of solar radiation may require that during the preheating phase the reflector devices are not
20 completely focused on the absorber tubes 5, but a so-called "diminished focus" is performed in which, for example, the focus only reaches an edge area of the absorber tube. In this way the heat input can be reduced. Alternatively, it can also be provided that the reflector devices are focused and unfocused alternately.
25 As soon as the absorber tubes have a temperature T, which is greater than or equal to the salt melting temperature, the introduction of the molten salt into the absorber tubes 5 can begin. In this respect, the molten salt pushes the medium heat carrier and press it to a secondary storage tank. In the embodiment example
30 represented, the secondary storage tank is formed by the storage tank 11, the used nitrogen being stored as a secondary heat transfer medium in the form of the gas bag contained in the storage tank 11.
Since the absorber tubes 5 are preheated to the temperature T, it is prevented that the molten salt 35 introduced into the absorber tubes 5 threatens to solidify.
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The regular operation of the solar thermal power station 100 can then be carried out, in which the molten salt is conducted with recirculation through the solar radiation receivers 1.
5 During the preheating process of the absorber tubes, the secondary heat transfer medium can be conducted with recirculation through the absorber tubes in the normal flow direction or also through the feed 17, so that the chains are traversed in parallel of parallel loop absorber tubes 9.
The solar thermal power station 100 according to the invention or the method according to the invention for the operation of a solar thermal power station 100 has the advantage that during the pauses the molten salt does not remain in the absorber tubes and therefore the danger that The molten salt solidifies in the absorber tubes or laborious heating of the molten salt is not necessary during the operating breaks. Due
15 upon evacuation of the molten salt to a storage tank 11 that is thermally insulated, the thermal energy contained in the molten salt can be stored in an intermediate way in large part during the operating break, so that it can be used in the restart of the solar thermal power station 100. Only in the longest running breaks, for example in the case of long periods of poor
20 winter time, heating is necessary before the plant starts up when the molten salt solidifies in the storage tank 11.
In the solar thermal power station 100 according to the invention or in the process according to the invention it may be provided that the molten salt from the absorber tubes is exited
25 before each break in operation. However, basically it can also be provided that the molten salt is only evacuated from the absorber tubes when the operating pause is planned for a longer predetermined time interval. For example, the daily emptying process of an entire solar field may be too laborious before a nighttime break when in summer the
30 nights are very short. Therefore, the method according to the invention can also be used only for longer periods of operation, such as periods of bad weather and for maintenance purposes.
The method according to the invention can also be used, for example, only for partial zones of a plant where repair measures are necessary in these.
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权利要求:
Claims (1)
[1]
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优先权:

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DE102014202633.4A|DE102014202633B4|2014-02-13|2014-02-13|Process for operating a solar thermal power plant as well as a solar thermal power plant|

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DE102014202633|2014-02-13|

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PCT/EP2015/052357|WO2015121139A1|2014-02-13|2015-02-05|Method for operating a solar thermal power plant, and solar thermal power plant|

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