JPH0346671B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of operating a solar thermal power generation device, and particularly to a method of operating a solar thermal power generation device with high solar heat utilization efficiency.

[Background of the invention]

A solar thermal power generation device is a device that collects sunlight energy as thermal energy and obtains electrical energy from this thermal energy. The solar energy obtained on the ground is affected by the weather, and it cannot be expected to obtain constant energy at all times. Rather, there are cases where rapid density changes occur repeatedly, and rapid thermal fluctuations cannot be directly applied to the power generation equipment side. In order to deal with this problem, in solar thermal power generation equipment, a heat storage device is installed between the concentrator and the power generation equipment, and a part of the collected heat is stored when the solar radiation conditions are good, and the heat is stored when the solar radiation conditions are bad. A method is used to extract heat from the equipment and continue generating electricity.

FIG. 9 shows an outline of a conventionally proposed solar thermal power generation device that is closest to practical use.

The solar thermal power generation device shown in Figure 9 is a 1000 kWe solar thermal power generation pilot lamp in the Sunshine Plan of the Ministry of International Trade and Industry, published in "Solar Thermal Power Generation Pilot Plant" edited by New Energy Development Organization, February 1981.

The solar thermal power generation device shown in FIG.
The main steam pipe 1 is connected to the main steam pipe 1 through the molten salt heat storage device 2 provided between
1, 12, a steam turbine 4 installed through the main steam pipe 12, a generator 5 connected thereto, a condenser 6 installed on the outlet side of the steam turbine 4, A water supply pump 7 provided in the water supply pipe connecting the condenser 6 and the condensing/heat collecting device 1, a valve 8 provided in the main steam pipe 12, a valve 8 provided in the steam inflow pipe 13 and the steam discharge pipe 14, It is equipped with check valves 9, 10, etc., and the molten salt heat storage device 2 and the accumulator heat storage tank 3 constitute a heat storage device. Also, molten salt heat storage device 2
For example, KE−LiF−NaF (42−45.6−11.5mol
%, melting point 454℃, latent heat of fusion 95kcal/Kg) or
KCl−LiCl (41.5−58.5mol%, 354℃, 57kcal/
Among molten salts such as Kg), those suitable for the operating conditions of the steam turbine 4 are used as heat storage materials, and the latent heat of fusion is used to store heat.

The operating method of this solar thermal power generation device is to supply water in the condensing heat collecting device 1 at a temperature of 50 to
The steam is superheated to a temperature 100°C higher and passed through the heat storage device 2 to store heat. Then, when power generation output is required, the outlet steam of the heat storage device 2 is supplied to the steam turbine 4 to generate power, and when power generation output is not required, the total heat collected steam amount is When the amount of collected steam is greater than the amount of steam consumed by the steam turbine 4, the surplus steam is led to the accumulator 3 through the steam inlet pipe 13 and stored therein. On the other hand, when the amount of heat collected steam is less, such as when solar radiation conditions are bad, the insufficient amount of steam is supplemented by the accumulator 3, and the generated saturated steam is guided to the heat storage device 2 through the steam discharge pipe 14, where it is superheated and vaporized into steam. Supply to turbine 4.
Furthermore, if power generation output is required when there is no solar radiation, all the required amount of steam is transferred to the accumulator 3.
The heat is then superheated and vaporized by the heat storage device 2 to drive the steam turbine. In other words, the heat storage device composed of the accumulator 3 and the molten salt heat storage device 2 absorbs fluctuations in the heat collecting steam conditions due to changes in the amount of solar radiation, and operates the plant safely and in accordance with the demands of the load side. I can do it. Therefore, in solar thermal power generation equipment, it is necessary to start power generation operation after a certain amount of heat has been stored in the heat storage device. A quantitative standard amount of heat storage is determined empirically, and power generation operation is started when the heat storage state reaches that value. In the conventional method of operating a solar thermal power generation device shown in this figure, the hot water storage pressure in the accumulator 3, which is a phenomenon that indicates the heat storage state of the heat storage device, is measured with a pressure gauge 15, and the hot water storage pressure corresponds to the standard heat storage amount. When the pressure rises to the set pressure, the steam turbine 4 and generator 5 are driven according to instructions from the plant control device 16 to obtain power generation output.

By the way, even though the heat source is free and inexhaustible, solar thermal power generation devices are of course highly efficient and inexhaustible.
Performance is required. In order to improve the performance of this solar thermal power generation device, it is necessary to (b) increase the heat collection efficiency of the solar heat collector, and (b) increase the efficiency of using the collected heat. Although research and development efforts are underway to improve the performance of solar thermal power generation devices, if we look at conventional operating methods for solar thermal power generation devices from the viewpoints of A and B above, they have the drawback of low heat utilization efficiency.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for operating a solar thermal power generation device with high performance, which eliminates the above-mentioned conventional drawbacks and improves solar heat utilization efficiency.

[Summary of the invention]

Generally, the efficiency of a steam turbine/generator increases as the steam conditions are higher and as the load is increased. As a result of conducting simulation evaluations of operating methods for solar thermal power generation equipment from this perspective, we have discovered a more efficient operating method. The evaluation calculation results that formed the basis for inventing the present invention will be explained below with reference to FIGS. 2 to 6.

The calculations were made using the 1000kWe solar thermal power generation device as an example, and based on typical actual heat collection data for the power generation device, simulation calculations were performed using the heat storage state at the start of power generation as a parameter, and the amount of generated power was predicted. The calculation method is based on the difference method.
In addition, the specifications of the 100kWe solar thermal power generation device are disclosed in the above-mentioned References 1 and 2 (edited by the Japan Electrical Manufacturers Association: Survey and Research on Solar Energy Utilization Systems, Sunshine Project Commissioned Research Results Report, published in March 1981). , and will be omitted here.

Figure 2 is one of the data used for evaluation calculations, and shows the data for the 100kWe solar power generation system as of September 1981.
This is the actual heat collection data on the 29th. On that day, the solar radiation conditions in the morning were extremely unstable, but stable solar radiation was obtained after 13:00, and the daily radiation was approximately 7,500 kg, approximately
An amount of collected steam of 10 MW/H was obtained and supplied to the heat storage system. Figure 3 similarly shows three other data; figure a is from August 20, 1981 (approx. 7500 kg,
(approximately 6.3MW・H), Figure b is from October 12, 1981 (approximately
16200Kg, 18.8MW・H), and figure c is 1981 10
This is the actual heat collection data for the 26th day of the month (approximately 26100Kg, 26.0MW・H). In other words, this evaluation calculation is based on 4 different
The power generation output is calculated based on the two heat collection data, using the heat storage state at the start of power generation as a parameter.

Figure 4 shows the conditions for starting power generation based on the heat collection data on September 29, 1981 shown in Figure 2 above, when the accumulator hot water storage pressure, which represents the heat storage state of the heat storage device, is
This shows the calculation results for predicting plant operation status when the pressure is 2.0MPa. As can be seen from Fig. 4, heat storage starts at around 1:15 p.m. when the collected steam is obtained, and as the heat storage progresses, the accumulator hot water storage pressure and the molten salt heat storage outlet steam temperature rise. At around 14:45, the accumulator hot water storage pressure reached the above level.
When the pressure reaches 2.0MPa, power generation operation begins by driving the steam turbine and generator. Initially 1000kW
However, the amount of collected steam is insufficient compared to the turbine steam consumption, so it is supplemented by the accumulator.
Therefore, the accumulator hot water storage pressure drops almost as soon as power generation starts. The saturated steam released from the accumulator is superheated into steam in the molten salt heat storage,
Supplied to steam turbine. Around 15:25, 16:35
As the amount of heat stored in the heat storage device decreases around 1 minute, the power generation output is reduced to 500 kW and 250 kW, respectively, and further increased to 16 kW.
Power generation operation will be stopped at around 1:55 p.m. In the case of such operating conditions, that is, in the heat collection data of September 29, 1981, if the heat storage condition for starting power generation is the accumulator hot water storage pressure of 2.0 MPa, approximately
A power generation amount of 1232kW/H can be obtained.

Figure 5 compares the heat collection data of September 29, 1981 with the results of predictive calculations using the accumulator hot water storage pressure at the start of power generation as a parameter. As the power generation start accumulator hot water storage pressure is made higher, the power generation start time becomes later because heat storage operation time is required, but the amount of power generation increases, reaching the maximum output (1281kW・H) at 2.7MPa. Analyzing these main factors based on calculation results shows that the higher the accumulator hot water storage pressure, the longer the time period during which it can operate under high load (1000 kW) improves the efficiency of the steam turbine.

However, even if the hot water storage pressure is increased beyond this, the power generation output tends to decrease due to a decrease in the turbine main steam temperature and heat radiation loss due to the decrease in the collecting steam conditions in the evening, but the difference is small.

FIG. 6 summarizes the results of calculations based on the four different heat collection data, including the above calculation results. In both cases, the higher the pressure, the more the power generation output tends to increase. October 12, 1981 and October 1981, when solar radiation conditions were good, i.e., there was a large amount of collected steam heat.
In the case of the 26th, it is thought that the higher the pressure, the more the power generation will increase, but it is not calculated here because it exceeds the operating limit pressure of the accumulator.

Based on the above evaluation calculation results, in order to increase the heat utilization efficiency of the solar thermal power generation device and improve the plant performance, (i) Start power generation operation after accumulating as much heat as possible and generate power under high load.

(ii) Use up the stored heat as much as possible.

It has become clear that this is important and is the basic idea of the present invention.

Based on the results of this study, the present invention measures the amount of heat storage, time of day, amount of solar radiation, etc. in order to achieve the above object, and starts power generation operation when predetermined conditions are reached.

[Embodiments of the invention]

A specific embodiment of the present invention will be described below with reference to FIG. In FIG. 1, parts that are the same as those of the conventional solar power generation device shown in FIG. 9 are designated by the same numbers, and 20 is a clock, 21 is a pyranometer, and 22 is a plant control device such as a computer. Such a clock 20, a pyranometer 221, and a control device 22 are conventionally installed in a general solar power generation device, and there are few items newly installed in order to carry out the present invention.

The controller 22 includes information such as the minimum amount of heat storage of the heat storage device to perform power generation operation, the maximum amount of heat storage of the heat storage device to perform power generation operation, the minimum amount of solar radiation at which heat collection operation can be performed, and the inability to perform heat collection operation below the minimum amount of solar radiation. Set the possible duration of solar radiation and the heat storage operation limit time. Here, the minimum amount of heat storage in the heat storage device is
This is the lowest amount of heat storage required to start power generation operation, and the appropriate amount of heat storage is such that even if the amount of solar radiation suddenly disappears, the heat storage device alone can continue power generation operation to some extent. For example, in the case of the 1000 kWe solar thermal power generation device, a value such as the hot water storage pressure of the accumulator, which is one of the indicators of the heat storage state of the heat storage device, is set. The maximum amount of heat storage of the heat storage device is the maximum amount of heat storage at which power generation starts, and when the heat storage state reaches this value, power generation operation is always performed and no more heat is stored. It is determined based on the design conditions, usage conditions, etc. of the heat storage device, and for example, in the case of the 1000 kWe solar power generation device, values such as the maximum usable hot water storage pressure of the accumulator are set. In addition, the amount of solar radiation at the lowest point is greater in the amount of heat collected than in the heat radiation loss in the heat collection system piping. In other words, it is the minimum amount of solar radiation that can provide an effective amount of heat collection. The duration of the amount of solar radiation during which the heat collection operation cannot be carried out is the duration of the amount of low solar radiation used to command the stop of the heat collection operation of the solar radiation collector when the amount of solar radiation decreases below the above-mentioned minimum amount of solar radiation. . In other words, the amount of sunlight may temporarily drop below the minimum amount of sunlight due to the passing of clouds, etc., but in such cases, there is no problem even if the heat collection operation is continued.
The duration of the amount of solar radiation that makes it impossible to carry out the heat collection operation is the minimum duration of the amount of low solar radiation that requires stopping the heat collection operation. Furthermore, the heat storage operation limit time is such that the effective amount of heat storage does not increase much even if the heat storage operation is performed because the amount of solar radiation decreases, and it is actually more effective to perform power generation operation while using the heat collection system and the heat storage system together. Although it depends on the scale of the heat collection system, heat storage system, and turbine generator system, as well as the season, a suitable time is, for example, between 2:00 p.m. and 4:00 p.m., when the amount of solar radiation gradually decreases. It is.

When the operating method of the solar thermal power generation device embodying the present invention is patterned for typical solar radiation conditions, it is expressed as shown in FIG.

One of them is to perform heat storage operation as much as possible,
When the pressure gauge 15 of the accumulator 3 reaches its maximum heat storage amount (the above set value), the control device 22
According to instructions, the turbine/generator is driven to obtain power generation output. Such an operating state occurs when solar radiation conditions are favorable, and is patterned as shown in FIG. 7a.

Second, if the amount of solar radiation falls below the minimum amount of solar radiation (the above-mentioned set value) during heat storage operation, if the amount of solar radiation recovers immediately, the heat collection operation - heat storage operation will continue, but the low amount of solar radiation When the predetermined time (the above set value) has elapsed, if the heat storage device has stored a heat storage amount equal to or greater than the minimum heat storage amount (the above set value), the measured values of the pyranometer 21, clock 20, and pressure gauge 15 According to instructions from the control device 22, the turbine/generator is driven to obtain power generation output. This kind of operating condition occurs when solar radiation is not obtained midway through the operation, as shown in Fig. 7b.
It is patterned as follows. Note that if the amount of heat storage has not reached the minimum amount of heat storage, power generation operation is impossible, and it is natural that it is necessary to wait for the next opportunity.

Third, when the time reaches the heat storage operation limit time (the above set value), if the heat storage device has reached the minimum heat storage amount (the above set value) or more, the clock 2
0. Based on the measured value of the pressure gauge 15, the turbine/generator is driven according to instructions from the control device 22 to obtain a power generation output. Such operating conditions are common when solar radiation is obtained from the middle, and are patterned as shown in FIG. 7c. Note that if the minimum amount of heat storage has not been reached even when the heat storage operation limit time is reached, the heat storage operation continues.

Fourthly, when the heat storage device reaches the minimum amount of heat storage (the above set value) after the heat storage operation limit time (the above set value), the control device 22 changes from the measured values of the clock 20 and the pressure gauge 15. Drives the turbine/generator according to instructions to obtain power generation output. In this case, it is patterned as shown in FIG. 7d. If the minimum amount of heat storage has not been reached even when it is time to stop the light condensing and heat collecting device, it goes without saying that it will be carried over to the next day.

Although the solar radiation conditions during the day may change in a complicated manner, the above four methods can be used in any case.

However, in the method of operating a solar thermal power generation device embodying the present invention, as described in the summary section of the invention, the turbine/generator is operated at a higher load and for a longer period of time than in the conventional method of operating a solar thermal power generation device. operation, and the stored heat can be used effectively without leaving any residual heat, greatly improving the performance of the solar thermal power generation device.

The basics of the implementation method of the present invention have been explained above, but
The present invention has various applications and embodiments other than those described above.

In the above embodiment, an acumulator is used as one of the heat storage devices, so a method of measuring the hot water pressure of the acumulator was shown as a method for measuring the amount of heat storage. The heat storage temperature of the other molten salt heat storage device may be measured. Furthermore, even when the heat storage device uses oil, pebbles, or the like as a heat storage material, the amount of heat storage can be determined by measuring the temperature, and the present invention does not limit the heat storage method. Furthermore, in the explanation of the present invention, water-steam, which is a turbine working medium, was used as an example of the heat collecting medium, but it goes without saying that other media such as oil, air, freon, or low-boiling point media may also be used. Furthermore, any method of concentrating sunlight may be used, such as a tower condensing method, a parabore condensing method, a flat plate concentrating method, or a concentrating method using a combination thereof. Further, in the embodiments of the present invention, the amount of solar radiation has been described as one of the conditions (the above-mentioned set value) for starting the power generation operation, but the operation can be performed similarly depending on the temperature of the heat collecting medium. FIG. 8 shows this other embodiment. In FIG. 8, 27 is a heat storage meter that measures the amount of heat stored in the heat storage device 30,
25 is a heat collecting medium temperature measuring device attached to the exit side of the light and heat collecting device 1. However, in this example,
Based on the measured values of the calorimeter 27, medium thermometer 25, and clock 20, power generation operation is started using the four methods described above.

The operating method of the present invention can be applied not only to solar thermal power generation devices, but also to improving the utilization efficiency of fluctuating thermal energy such as other solar heat utilization devices, factory exhaust heat, and natural energy. [Effects of the Invention] As described above, according to the present invention, it is possible to obtain a method of operating a solar thermal power generation device that utilizes a high amount of heat, that is, has good performance.

[Brief explanation of drawings]

FIG. 1 shows a solar power generation device implementing the present invention. FIG. 2 shows heat collection data used as data for simulation calculations for examining the effects of the present invention, and FIG. 3 shows other heat collection data. Figure 4 shows an example of simulation calculation of the operating characteristics of a solar thermal power generation device, Figure 5 compares the results of simulation calculation using the power generation operation start conditions as parameters, and Figure 6 shows the simulation calculation for each of the above calculation data. This is a summary of the results. FIG. 7 shows a pattern of the operating method of the solar thermal power generation device of the present invention.
FIG. 8 shows another embodiment of the present invention,
FIG. 9 shows a conventional solar power generation device. 1... Light condensing heat collecting device, 2... Molten salt heat storage device, 3
...Accumulator, 4...Steam turbine, 5...
... Generator, 6 ... Condenser, 7 ... Water pump, 8
...Valve, 9, 10, 11, 12, 13, 14...
Piping, 15...Pressure gauge, 16...Control device, 1
7, 18, 23, 24... signal line, 20... clock, 21... pyranometer, 22... control device, 25...
...Thermometer, 27...Calorimeter, 30...Heat storage device.

Claims (1)

[Scope of Claims] 1. Solar thermal power generation consisting of a concentrator and heat collector that condenses sunlight and heats a medium, a heat storage device that stores the medium heated and heated by sunlight or the concentrated heat, and a turbine/generator. In the method of operating the device, when starting the turbine/generator, (a) the minimum amount of heat storage of the heat storage device that will perform power generation operation, (b) the maximum amount of heat storage of the heat storage device that will perform power generation operation, and (c) whether heat collection operation can be performed. Set the minimum amount of solar radiation, (d) the duration of the amount of solar radiation below the minimum amount of solar radiation that makes it impossible to perform heat collection operation, (e) the time limit for thermal storage operation, and (a) when the heat storage device reaches the maximum amount of heat storage (the setting value in (b) above). When the amount of solar radiation falls below the minimum amount of solar radiation (set value in C above) and the duration of the amount of solar radiation during which heat collection operation cannot be performed has elapsed (set value in D above), the heat storage device is activated. Minimum heat storage amount (set value in A above)
c time is the heat storage operation limit time (setting value in e above)
When the heat storage device reaches the minimum heat storage amount (set value in A above) or more, time d reaches the heat storage operation limit time (set value in E above).
Later, when the heat storage device reaches the minimum amount of heat storage (set value in A above), the turbine/generator will be started to generate power output when any of the conditions a to d above are met. A method of operating a solar thermal power generation device characterized by: 2. In a method of operating a solar thermal power generation device consisting of a concentrator and heat collector that condenses sunlight and heats a medium, a heat storage device that stores the medium heated and heated by sunlight or the condensed heat, and a turbine/generator, When starting the turbine/generator, the following information should be taken: (a) the minimum amount of heat storage in the heat storage device for power generation operation, (b) the maximum amount of heat storage in the heat storage device for power generation operation, (c) the minimum usage temperature of the heat collection medium, (d) the heat storage operation limit time. , when the heat storage device reaches the maximum heat storage amount (set value in B above), b. When the temperature of the heat collecting medium falls below the minimum usage temperature (set value in C above), the heat storage device has reached the minimum amount of heat storage (set value in A above) or more, c time is the heat storage operation limit time (set value in D above)
When the heat storage device reaches the minimum heat storage amount (set value in A above) or more, time d reaches the heat storage operation limit time (set value in D above).
Later, when the heat storage device reaches the minimum amount of heat storage (set value in A above), the turbine/generator will be started to generate power output when any of the conditions a to d above are met. A method of operating a solar thermal power generation device characterized by: