WO2014065158A1 - Combined power generation plant - Google Patents

Abstract

In order to provide a combined power generation plant with which an increase in power generation costs can be prevented, this combined power generation plant is equipped with: a first power generation plant that uses solar heat to generate steam; a second power generation plant that uses a boiler to generate steam; a steam turbine; and power generators (64, 65). The first power generation plant is equipped with a low-temperature heating device (13), a steam separation device (4), and a high-temperature heating device (14) that uses solar heat to superheat the steam separated by the steam separation device (4). The second power generation plant is equipped with: a steam generation unit having a reheated steam system heat exchanger (10a) and a primary steam system heat exchanger (10b); a water supply pump (11); and a water supply heater (12) that uses extracted steam from the steam turbine to heat the water from the water supply pump (11). In addition, a high-pressure turbine (60), a medium-pressure turbine (61), and a low-pressure turbine (62) are provided. In a first power generation mode that uses the first power generation plant, power is generated with the medium-pressure turbine (61) and the low-pressure turbine (62). In a second power generation mode that uses the second power plant, power is generated with the high-pressure turbine (60), the medium-pressure turbine (61), and the low-pressure turbine (62).

Description

Combined power plant

The present invention collects heat from the sun and generates steam with the heat, and a first power plant (solar thermal power plant) using a solar boiler plant, and burns or generates heat (for example, in the case of nuclear fuel). Alternatively, the present invention relates to a combined power plant combining a second power plant using a boiler plant different from the solar boiler plant that generates steam by recovering the heat of high-temperature exhaust gas.

The amount of heat collected in a solar boiler is unavoidably repeated as the amount of sunshine changes rapidly in a short period of time, such as the sun being blocked by clouds depending on the location.

On the other hand, from the viewpoint of obtaining as much total annual heat collection amount as possible, solar boilers are often introduced in a region called a sun belt region, that is, a region where annual direct solar radiation exceeds 2000 kWh / m ² .

In the Sunbelt area, there are many clear skies throughout the year, and sudden changes in the amount of sunshine due to weather changes are unlikely to occur, and the amount of heat collected is stable over time, so the aforementioned problems are unlikely to occur.

However, in areas other than the sun belt, such as Japan, sudden fluctuations in the amount of solar radiation due to weather changes and cloud movements frequently occur throughout the day, and rapid increases and decreases in the amount of collected heat occur repeatedly. For this reason, it is important to deal with such problems.

The first power generation plant of the concentrating / heat collecting type is roughly divided into a single power plant and a combined power plant. In a stand-alone power plant, most of the heat is supplied by solar heat, and part of it is backed up by fossil fuel. On the other hand, in a combined power plant, most of the heat is supplied by fossil fuels and nuclear fuel, and part of it is backed up by solar heat.

In both the single power plant and the combined power plant, heat from sunlight is collected and used as a heat source, and a condensing and collecting device is also used in common. Has been.

Generally, as a condenser / heat collector, a heat transfer tube is arranged above the inner peripheral curved surface of a condensing mirror extending in a bowl shape, and sunlight is condensed on the heat transfer tube by the condensing mirror, thereby transferring heat. A large number of trough-type, flat or slightly curved condenser mirrors that change the angle little by little, and produce a large number of heat transfer tubes above the condenser mirror group. The heat transfer tube panel is installed on a tower having a predetermined height, while a Fresnel type that condenses and collects sunlight on the heat transfer tube by the collection mirror group to generate steam. There is a tower type which arranges a condensing mirror (heliostat) and collects sunlight on a heat transfer tube panel by the condensing mirror (heliostat) group to generate steam.

Among these, the trough type and the Fresnel type have a short focal length, and the solar condensing degree (heat density at the heat collecting part) is low. On the other hand, since the tower type has a long focal length, it has a feature that the degree of solar condensing (heat density at the heat collecting portion) is high.

If the heat density in the heat collecting part is high, the amount of heat collected per unit heat transfer area is high, and higher temperature steam can be obtained. However, when the heat density is simply increased and the phase is changed from the water state to the superheated steam, there is a problem that a high temperature region is locally formed and the heat transfer tube is damaged.

In thermal power boilers, etc., the amount of fuel is properly managed and there is no such damage to the heat transfer tubes. However, in the case of solar heat, the heat input varies greatly, so it is possible to avoid thermal damage to the heat transfer tubes. Have difficulty.

In such a tower-type solar boiler with a high heat density, there are proposals described in Patent Document 1 and Patent Document 2, for example. FIGS. 24 and 25 are diagrams created based on such a proposal. FIG. 24 is a schematic configuration diagram of a solar heat boiler, and FIG. 25 is an enlarged schematic configuration diagram of a heat collecting apparatus used for the solar heat boiler. In these figures, reference numeral 1 is a heat collecting device, 2 is an evaporator, 3 is a superheater, 4 is a brackish water separator, 5 is a tower, 6 is a heliostat, 7 is the sun, 8 is a steam turbine, and 9 is a generator. , 11 is a water supply pump.

As shown in FIG. 25, the heat collecting apparatus 1 is functionally separated into an evaporator 2 (reheat steam system heat exchanger) and a superheater 3 (main steam system heat exchanger), and the evaporator 2 and the superheater. A brackish water separator 4 is arranged between the three. As shown in FIG. 24, the heat collecting apparatus 1 is installed on a tower 5 having a height of about 30 to 100 m, and reflects light from the sun 7 by a heliostat 6 installed on the ground. Then, the evaporator 2 and the superheater 3 are heated by focusing on the heat collecting device 1. Finally, the superheated steam generated by the heat collecting apparatus 1 is sent to the steam turbine 8 to rotate the generator 9 to generate power.

International Publication No. 2009/129166 A2 International Publication No. 2010 / 048578A1 JP 56-85652 A JP 2011-163592 A

However, in the prior art described above, the brackish water separator 4 as well as the evaporator 2 and the superheater 3 must be installed on the tower 5 having a height of 30 to 100 m. For this reason, in addition to the evaporator 2 and the superheater 3 which are aggregates of a large number of heat transfer tubes, the load of the brackish water separator 4 having saturated water therein can be supported, and can withstand earthquakes sufficiently. Therefore, there is a problem that the equipment cost and the construction cost increase.

Moreover, since it is necessary to raise water to the place of the brackish water separator 4 of the high place with the feed water pump 11, the expensive feed water pump 11 with a high pumping capacity is needed, and, thereby, an installation cost and a running cost also become high.

Furthermore, in order to avoid thermal damage to the heat transfer tubes constituting the evaporator 2 and the superheater 3, it is necessary to suppress the amount of heat collected in the heat collecting device 1. The amount and temperature fluctuate, and as a result, there is a problem that the power generation amount is not constant.

Moreover, in order to avoid the thermal damage of the heat exchanger tube of the evaporator 2, since the circulating flow rate of the heat medium is set high, the power consumption of the feed water pump 11 is large, and the internal ratio that is the ratio of the power generation amount is There is also a problem that it is big.

Furthermore, in a combined power plant combining such a solar thermal power plant and a thermal power plant, superheated steam generated by the solar thermal power plant or the thermal power plant is any of a high pressure steam turbine, an intermediate pressure steam turbine, and a low pressure steam turbine. It was not considered whether to generate electricity by introducing it into a steam turbine. For this reason, efficient use of superheated steam is not possible, which may increase power generation costs.

An object of the present invention is to provide a combined power plant that eliminates the disadvantages of the prior art and does not cause an increase in power generation cost.

In order to achieve the above object, the present invention provides:
A first power generation plant that collects solar heat and generates steam by the heat, a second power generation plant that generates steam by burning or generating heat from the fuel, or recovering heat of exhaust gas, and the first power generation A combined power plant comprising a steam turbine that rotates by introducing steam generated in a plant or a second power plant, and a generator that is rotationally driven by the steam turbine,
The first power plant separates a water-steam two-phase flow generated by the low-temperature heating device provided with a horizontal heat transfer tube for heating water supplied from a feed water pump with the solar heat into water and steam. A brackish water separator, a high-temperature heating device that superheats steam separated by the brackish water separator with solar heat, and a circulation pump that supplies water separated by the brackish water separator to the low-temperature heating device,
The second power plant includes a steam generator having a reheat steam heat exchanger and a main steam heat exchanger for generating steam, a feed water pump for supplying water to the steam generator, and a feed pump for supplying the water. A water heater that heats the water to be discharged with the extracted steam from the steam turbine,
The steam turbine includes a high pressure steam turbine, an intermediate pressure steam turbine, and a low pressure steam turbine,
In the first power generation mode in which power generation is performed using the first power plant, the steam superheated by the high-temperature heating device of the first power plant is guided to the intermediate pressure steam turbine and the low pressure steam turbine to generate power,
In a second power generation mode in which power generation is performed using the second power plant, steam superheated by the main steam heat exchanger of the second power plant is transferred to the high-pressure steam turbine, intermediate-pressure steam turbine, and low-pressure steam turbine. It is characterized by being guided and generating electricity.

The present invention has the above-described configuration, and can provide a combined power plant that does not increase power generation costs.

It is a schematic block diagram which shows the use condition in the 2nd electric power generation mode of the combined power plant which concerns on 1st Embodiment of this invention. It is a schematic block diagram which shows the use condition in the 1st electric power generation mode of the combined power plant. In the first embodiment, the extraction provided between the high-pressure steam turbine, the intermediate-pressure steam turbine, the low-pressure steam turbine and the feed water heater in accordance with the change in the passing steam amount of the steam valve provided on the outlet side of the high-temperature heating device It is the figure which showed an example which adjusts the opening degree of a valve. It is a principle figure for demonstrating the structure of the tower type condensing / heat collecting apparatus which installed the high temperature heating apparatus which concerns on 1st Embodiment of this invention. It is an expansion schematic block diagram of the heat exchanger tube panel used for the high temperature heating apparatus. In the first power generation mode of the combined power plant according to the first embodiment, the figure (a) shows the power generation output, the figure (b) shows the profit ratio from the annual power sale, and the figure (c). ) Is an initial cost ratio for constructing a light collecting / heat collecting device, and FIG. 4D is a diagram showing an example of a ratio of power generation cost. It is a schematic block diagram which shows the use condition in the 2nd electric power generation mode of the combined power plant which concerns on 2nd Embodiment of this invention. It is a schematic block diagram which shows the use condition in the 1st electric power generation mode of the combined power plant which concerns on the 2nd Embodiment. It is a principle figure for demonstrating the structure of the trough-type condensing and heat collecting apparatus used by the 2nd Embodiment. It is a principle figure for demonstrating the structure of the Fresnel type condensing and heat collecting apparatus used by the 2nd Embodiment. It is a schematic block diagram which shows the use condition in the 2nd electric power generation mode of the combined power plant which concerns on 3rd Embodiment of this invention. It is a schematic block diagram which shows the use condition in the 1st electric power generation mode of the combined power plant which concerns on the 3rd Embodiment. It is a partially expanded sectional view of the vicinity of a heat transfer tube used for a trough-type (or Fresnel-type) light collecting / collecting device. It is a schematic block diagram which shows the use condition in the 2nd electric power generation mode of the combined power plant which concerns on 4th Embodiment of this invention. It is a schematic block diagram which shows the use condition in the 1st electric power generation mode of the combined power plant which concerns on the 4th Embodiment. It is a characteristic view which shows the relationship between the water level L of a brackish water separator, and the exit quality X of a low-temperature heating apparatus. Figure (a) shows the flow of water-steam two-phase flow in the horizontal heat transfer tube of the low-temperature heating apparatus, and Fig. (B) shows water-steam two-phase flow in the horizontal heat transfer tube. It is the schematic diagram which showed each flow state. It is a schematic block diagram which shows the use condition in the 2nd electric power generation mode of the combined power plant which concerns on 5th Embodiment of this invention. It is a schematic block diagram which shows the use condition in the 1st electric power generation mode of the combined power plant which concerns on the 5th Embodiment. It is a schematic block diagram which shows the use condition in the 2nd power generation mode of the combined power plant which concerns on 6th Embodiment of this invention. It is a schematic block diagram which shows the use condition in the 1st electric power generation mode of the combined power plant which concerns on 6th Embodiment of this invention. It is the flow pattern diagram of the gas-liquid two-phase flow which separated the flow state of the gas-liquid two-phase flow in a horizontal pipe by a flow mode, and arranged according to the gas phase apparent velocity and the liquid phase apparent velocity in the tube. It is a schematic block diagram of the solar thermal power generation plant which concerns on 7th Embodiment of this invention. It is a schematic block diagram of the conventional solar thermal boiler. It is an expansion schematic block diagram of the heat collecting device used for the solar thermal boiler.

(First embodiment)
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a usage state in the second power generation mode of the combined power plant according to the first embodiment of the present invention, and FIG. 2 shows a usage state in the first power generation mode of the combined power plant. It is a schematic block diagram. 1 and FIG. 2 have the same configuration, but different devices are used depending on the power generation mode, as will be described later.

This combined power plant has a first power plant (solar thermal power plant) that uses a solar boiler plant that collects heat from the sun and generates steam with the heat, and burns or generates heat (for example, in the case of nuclear fuel) Or a second power plant using a boiler plant that generates steam by recovering the heat of high-temperature exhaust gas.
<First power generation mode>
In the first power generation mode of the combined power plant, as shown in FIG. 2, the solar water supply valve 20 is opened and the thermal power supply valve 66 is closed.

Water supplied from the water supply pump 11 passes through the water supply valve 19, is sent to the water supply heater 12, is heated, passes through the solar water supply valve 20, and is introduced into the low temperature heating device 13 through the brackish water separator 4. In this low temperature heating device 13, the feed water is heated by the light 32 from the sun 7, and the water is circulated between the brackish water separator 4 and the low temperature heating device 13 by the circulation pump 15.

The water-steam two-phase fluid generated by the low temperature heating device 13 is separated into saturated water and saturated steam by the brackish water separation device 4, and the separated steam is sent to the high temperature heating device 14 installed on the tower 16. . The steam introduced into the high-temperature heating device 14 is further superheated by solar heat reflected by the heliostat 6 and guided to the high-temperature heating device 14.

The superheated steam generated by the high-temperature heating device 14 is sent to the intermediate-pressure steam turbine 61 (A to A in the figure), and rotates the intermediate-pressure steam turbine 61 and the low-pressure steam turbine 62. The turbine generator 65 generates power.

In order to adjust the amount of steam supplied to the intermediate pressure steam turbine 61, a feed water valve 19 is provided between the feed water pump 11 and the feed water heater 12, and a steam is provided between the high temperature heating device 14 and the intermediate pressure steam turbine 61. A valve 18 is installed. Further, a part of steam is extracted from the intermediate pressure steam turbine 61 and the low pressure steam turbine 62 and sent to the feed water heater 12 through the extraction valve 17 (C ₂ and C ₃ to C in the figure), and the feed water is heated. It has become a system.

<Second power generation mode>
In the second power generation mode of the combined power plant of the present embodiment, as shown in FIG. 1, the thermal water supply valve 66 is opened and the solar heat supply valve 20 is closed.

Water supplied from the water supply pump 11 passes through the water supply valve 19 and is sent to the water supply heater 12 to be heated. The water heated by the feed water heater 12 passes through a thermal water supply valve 66 and is introduced into a boiler plant 10 that generates steam by burning or generating heat or recovering the heat of exhaust heat gas.

The boiler plant 10 is provided with a reheat steam heat exchanger 10a and a main steam heat exchanger 10b, and water heated by the feed water heater 12 is overheated by the main steam heat exchanger 10b. Is done. The superheated steam generated in the main steam heat exchanger 10b is sent to the high-pressure steam turbine 60 (from B to B in the figure), rotates the high-pressure steam turbine 60, and generates electricity by the generator 64 for the high-pressure steam turbine by the rotation. .

Further, the superheated steam emitted from the high-pressure steam turbine 60 is again introduced into the boiler plant 10 and sent to the reheat steam system heat exchanger 10a. The steam superheated in the reheat steam system heat exchanger 10a is sent to the intermediate pressure steam turbine 61 (E to E in the figure), and rotates the intermediate pressure steam turbine 61 and the low pressure steam turbine 62, and the rotation causes the medium pressure / Power generation is performed by a low-pressure steam turbine generator 65.

The reheat steam heat exchanger 10a and the main steam heat exchanger 10b are names given to distinguish the heat exchangers 10a and 10b from the boiler plant 10 side.

In order to adjust the amount of steam supplied to the high-pressure steam turbine 60, a feed water valve 19 is provided between the feed water pump 11 and the feed water heater 12, and a steam valve 67 is provided between the boiler plant 10 and the high-pressure steam turbine 60, respectively. is set up.

Further, some steam is extracted from the high-pressure steam turbine 60, the intermediate-pressure steam turbine 61, and the low-pressure steam turbine 62 and sent to the feed water heater 12 through the extraction valve 17 (C ₁ , C ₂ , C in the figure). ₃ to C), the feed water is heated.

FIG. 3 shows that in the first power generation mode, as shown in FIG. 2, the medium pressure steam turbine 61 and the low pressure steam turbine 62 are accompanied by a change in the amount of steam passing through the steam valve 18 provided on the outlet side of the high temperature heating device 14. It is the figure which showed an example which adjusts the opening degree of the extraction valve 17 provided in the exit side. 4A shows the change in the amount of steam passing through the steam valve 18, and FIG. 4B shows the adjustment of the opening degree of the extraction valve 17 accompanying the change in the amount of steam.

As shown in this figure, when the amount of steam passing through the steam valve 18 increases, the opening degree of the extraction valve 17 is decreased, and conversely, when the amount of steam passing through the steam valve 18 decreases, the opening degree of the extraction valve 17 is increased. In this way, by operating the extraction valve 17 according to the amount of steam supplied from the high-temperature heating device 14, the amount of extraction of the intermediate-pressure steam turbine 61 and the low-pressure steam turbine 62 is increased or decreased (adjusted). Large fluctuations can be avoided.

It should be noted that the adjustment of the extraction amount of the intermediate-pressure steam turbine 61 and the low-pressure steam turbine 62 according to the amount of steam supplied from the high-temperature heating device 14 can be applied to other embodiments described later.

FIG. 4 is a principle diagram for explaining the configuration of a tower-type light collecting / collecting device provided with the high-temperature heating device 14.
As shown in FIG. 4, the tower type light collecting and heat collecting apparatus is provided with a high temperature heating device 14 (heat transfer tube panel 27) on a tower 16 having a predetermined height (about 30 to 100 m). On the other hand, a large number of heliostats 6 are arranged in various directions on the ground surface, and the heliostats 6 are focused on the high-temperature heating device 14 (heat transfer tube panel 27) while tracking the movement of the sun 7, and overheated. It is a mechanism to generate steam.

This tower-type concentrator / heat collector has the advantage that it can generate higher-temperature steam than the trough-type concentrator / collector, increasing the turbine efficiency and obtaining more power. is doing.

FIG. 5 is an enlarged schematic configuration diagram of the heat transfer tube panel 27 used in the high-temperature heating device 14. The heat transfer tube panel 27 includes a superheater lower header 22 that evenly distributes the steam from the brackish water separator 4 and superheater transmissions arranged in parallel to distribute the steam distributed by the superheater lower header 22. It consists of a heat pipe 21 and a superheater upper header 23 that collects superheated steam flowing out from the superheater heat transfer pipe 21.

The low-temperature heating device 13 and the brackish water separation device 4 have a large amount of water inside, and the entire device becomes heavy. Therefore, the ground surface or a low foundation with a height of, for example, about 1 to 2 m is used near the ground surface. It is installed. Thus, since the low-temperature heating device 13 and the brackish water separation device 4 are installed on or near the ground surface, it is not necessary to raise the water to a height of, for example, 30 to 100 m as in the prior art, so that the pumping capacity is low. An inexpensive feed water pump 11 can be used.

On the other hand, the high-temperature heating device 14 is installed at a height of 10 m or more (for example, 30 to 100 m) from the ground surface in order to collect the light 32 from the heliostat 6 with high light density. Since the fluid flowing inside the high-temperature heating device 14 is only steam, it is much lighter than the heat collecting device 1 (see FIG. 25) comprising the general evaporator 2, superheater 3, and brackish water separator 4. It is small. Note that the heat collection ratio of the low temperature heating device 13 and the high temperature heating device 14 is approximately 9: 1 to 7: 3, and the heat collection amount of the high temperature heating device 14 is much smaller than that of the low temperature heating device 13.

FIG. 6 shows, in the first power generation mode of the combined power plant according to the present embodiment, for each steam turbine used, FIG. 6 (a) shows the power generation output, FIG. Fig. (C) shows the initial cost ratio for constructing the concentrator / heat collector, and Fig. (D) shows an example of the ratio of power generation cost in consideration of Fig. (B) and (c). FIG.

Note that the above-described steam turbines used indicate the use of high-pressure / medium-pressure / low-pressure turbines, use of medium-pressure / low-pressure turbines, and use of low-pressure turbines shown on the horizontal axis of FIG. Further, the ratios shown in (b) to (d) in the figure are based on the medium pressure / low pressure steam turbine (1.0).

In general, it goes without saying that generating high-temperature and high-pressure steam and increasing the number of steam turbines used increase the power generation output. For example, as shown in FIG. 2A, when a constant load operation is performed with three steam turbines of high-pressure / medium-pressure / low- pressure steam turbines 60, 61, 62, two turbines of 350MWe, medium-pressure / low- pressure steam turbines 61, 62 are provided. Assuming that power can be generated at 254 MWe when operating at a constant load with a steam turbine and 160 MWe when operating at a constant load with only a low-pressure steam turbine 62, as shown in FIG. The more you increase.

However, when the high-pressure / medium-pressure / low- pressure steam turbines 60, 61, 62 are used, the tower-type concentrating / collecting device corresponds to the reheat steam heat exchanger 10a (see FIG. 1) of this embodiment. Instead, it is necessary to superheat the steam from the high-pressure steam turbine 60 with the tower-type concentrator / heat collector and send it to the intermediate-pressure steam turbine 61, so that the scale of the tower-type concentrator / heat collector is expanded. As shown in FIG. 3C, the initial cost of the light collecting / heat collecting device increases.

On the other hand, as shown in FIG. 4D, it can be seen that in the first power generation mode, the medium-pressure / low- pressure steam turbines 61 and 62 are operated at a constant load to suppress the increase in power generation cost most.

According to the combined power plant according to the present embodiment, the medium pressure / low pressure steam turbines 61, 62 are used in the first power generation mode, and the high pressure / medium pressure / low pressure steam turbines 60, 61, 62 are used in the second power generation mode. Is used. Further, the high-pressure steam turbine generator 64 and the intermediate-pressure / low-pressure steam turbine generator 65 are used to prevent the high-pressure steam turbine 60 from rotating unnecessarily in the first power generation mode.
Thereby, the steam turbines 60, 61, 62 suitable for the respective steam conditions of the first power generation mode and the second power generation mode can be used, and an increase in power generation cost can be suppressed.
This effect is also obtained in the second and subsequent embodiments.

The high-pressure steam turbine 60, the medium-pressure steam turbine 61, and the low-pressure steam turbine 62 do not have to have two rotational axes. For example, a single-shaft generator for high-pressure / medium-pressure / low-pressure steam turbines is prepared. In the first power generation mode, the high-pressure steam turbine may be idled.

(Second Embodiment)
FIG. 7 is a schematic configuration diagram showing a use state in the second power generation mode of the combined power plant according to the second embodiment of the present invention, and FIG. 8 shows a use state in the first power generation mode of the combined power plant. It is a schematic block diagram. Although the configuration of the complex plant shown in FIG. 7 and FIG. 8 is the same, the equipment to be used differs depending on the power generation mode as in the first embodiment.

This embodiment is different from the first embodiment in that a low-temperature heating device 24 including a trough-type or Fresnel-type light collecting / heat collecting device is used as shown in FIG. Other configurations and power generation mechanisms are the same as those in the first embodiment, and a duplicate description is omitted.

FIG. 9 is a principle diagram for explaining the configuration of a trough-type condensing / heat collecting device.
As shown in FIG. 9, this trough-type condensing / heat collecting device individually arranges heat transfer tubes 31 horizontally at the focal position above the inner peripheral curved surface of the condensing mirror 30 extending in a bowl shape, and sunlight 32 Is condensed on the heat transfer tube 31 by the condenser mirror 30. Water 33 circulates in each heat transfer tube 31, and the water 33 is heated by the heat collected in the heat transfer tube 31, and a water-steam two-phase fluid 34 is obtained from the heat transfer tube 31. .
This trough-type condensing / heat collecting apparatus has the advantages that it does not require advanced condensing technology and has a relatively simple structure.

In this embodiment, the low-temperature heating device 24 composed of a trough-type condensing / heat collecting device is used, but a low-temperature heating device 24 composed of a Fresnel-type condensing / heat collecting device may be used.

FIG. 10 is a principle diagram for explaining the configuration of a Fresnel type light collecting / collecting device.
As shown in FIG. 10, this Fresnel type condenser / heat collector has a large number of planar or slightly curved condenser mirrors 35 arranged at slightly different angles and several meters above the condenser mirror 35 group. A group of heat transfer tubes 31 in the form of a panel is arranged horizontally.

A mechanism in which the sunlight 32 is condensed on the heat transfer tubes 31 by the condensing mirror 35 group, and the water 33 flowing through the heat transfer tubes 31 is heated to obtain the water-steam two-phase fluid 34 from the heat transfer tubes 31. It has become.

This Fresnel type condenser / heat collector is easier to manufacture than the trough-type curved condenser mirror 30, can be produced at a low cost, and has the advantage that the condenser mirror 35 is less susceptible to wind pressure. ing.

(Third embodiment)
FIG. 11 is a schematic configuration diagram showing a use state of the combined power plant according to the third embodiment of the present invention in the second power generation mode, and FIG. 12 shows a use state of the combined power plant in the first power generation mode. It is a schematic block diagram. 11 and FIG. 12 have the same configuration, but the devices used differ depending on the power generation mode as in the first embodiment.

In the case of the present embodiment, as shown in FIG. 12, a thermometer that measures the temperature and flow rate of the fluid on the fluid return pipe 36 provided between the outlet side of the low-temperature heating device 24 and the inlet side of the brackish water separator 4. 25 and a flow meter 28 are provided, and measurement signals from the thermometer 25 and the flow meter 28 are input to the arithmetic unit 26.

The arithmetic unit 26 outputs a control signal for controlling the opening of the water supply valve 20, that is, the water supply flow rate, to the water supply valve 20 so that the outlet fluid temperature of the low temperature heating device 24 is always 300 ° C. or lower. Yes.

By limiting the outlet fluid temperature of the low-temperature heating device 24 to 300 ° C. or less in this way, the structure of the low-temperature heating device 24 composed of a trough-type (or Fresnel-type) light collecting / collecting device can be simplified, and transmission can be performed. There is an advantage that a decrease in thermal efficiency can be suppressed.

Specifically, the outer glass tube cracks due to the difference in thermal elongation between the heat transfer tube and the outer glass tube, which is a problem when using a trough-type (or Fresnel-type) light collecting / collecting device at a high temperature. In addition, it is possible to suppress the radiative cooling due to the heat transfer tube surface temperature being increased.

FIG. 13 is a partially enlarged cross-sectional view of the vicinity of a heat transfer tube used in a trough-type (or Fresnel-type) light collecting / collecting device. As shown in the figure, an outer peripheral glass tube 42 is disposed on the outer periphery of the horizontal heat transfer tube 38 to form a double structure. The outer peripheral glass tube 42 is provided in order to suppress heat release from the horizontal heat transfer tube 38 to the outside air by making the space between the horizontal heat transfer tube 38 and the outer peripheral glass tube 42 airtight or vacuum.

The heat transfer tubes 38 are joined to form a long heat transfer tube 38 by joining a plurality of heat transfer tubes in the axial direction. Since the heat transfer tube 38 is made of a metal such as carbon steel stainless steel, FIG. As shown, the heat transfer tubes 38 can be welded 43 to a predetermined length.

On the other hand, since the outer glass tube 42 cannot directly weld them, as shown in FIG. 13, metal bonding pipes 44 are respectively arranged on the inner side and the outer side of the joint portion of the outer glass tube 42. The outer peripheral glass tube 42 and the bonding tube 44 are welded to each other so that the outer peripheral glass tubes 42 are connected to each other with a predetermined length via the bonding tube 44.

Thus, when the difference in thermal expansion between the heat transfer tube 38 and the outer peripheral glass tube 42 connected to a predetermined length increases inside the outer peripheral glass tube 42 connected to a predetermined length, the outer peripheral glass tube 42 and The vicinity of the connecting portion of the bonding tube 44 may be broken.

In addition, as the surface temperature of the heat transfer tube 38 increases, the temperature difference from the outside air increases, and the heat dissipation to the outside air increases due to the radiation cooling phenomenon (heat moves by the fourth power difference). is there.

Therefore, in this embodiment, the temperature of the outlet fluid of the low-temperature heating device 24 is limited to 300 ° C. or less, specifically 250 to 300 ° C., and the peripheral glass due to the difference in thermal expansion between the heat transfer tube 38 and the peripheral glass tube 42. Radiation cooling due to cracking of the tube 42 and an increase in the surface temperature of the heat transfer tube 38 is suppressed.

The heat collection amount of the high temperature heating device 14 can be adjusted based on the measurement signals of the thermometer 25 and the flow meter 28 so that the outlet fluid temperature of the high temperature heating device 14 is 300 ° C. or higher. The amount of heat collection can be controlled by adjusting the opening of the water supply valve 19 and changing the water supply flow rate.
Other configurations and power generation mechanisms are the same as those in the second embodiment, and a duplicate description is omitted.

In this embodiment, the thermometer 25 and the flow meter 28 are installed on the outlet side of the low temperature heating device 24, and the feed water flow rate to the low temperature heating device 24 is adjusted so that the measured temperature and flow rate become predetermined values. The thermometer 25 and the flow meter 28 are installed on the outlet side of the low-temperature heating device 13 (see FIG. 2) used in the first embodiment, so that the measured temperature and flow rate become predetermined values. The amount of heat collection of 24 can also be adjusted.

In any of the above-described embodiments, the low-temperature heating device 13 (24) and the high-temperature heating device 14 ultimately use a fluid consisting of steam (water) that drives the intermediate-pressure steam turbine 61 and the low-pressure steam turbine 62 as a heat medium. This is a light collecting / collecting device that directly heats it with sunlight 32.

Therefore, since the solar heat boiler does not use a heat exchanger other than the low-temperature heating device 13 (24) and the high-temperature heating device 14, the configuration of the entire boiler device is simple, and the size and cost can be reduced. have.

On the other hand, when a fluid composed of water-steam is directly heated by sunlight 32, a Fresnel type or trough type light collecting / collecting device used in the low temperature heating device 13 (24) is particularly preferably disposed in the heat transfer tube. When a phase change occurs from water to steam, resulting in a two-phase flow, the heat transfer tubes can be locally damaged thermally.

That is, in particular, the Fresnel type or trough type light collecting / collecting device receives heat in the concentrated range of the outer peripheral surface of the horizontally arranged heat transfer tubes, so that the heat flux distribution is uneven over the outer periphery of the heat transfer tubes. It is the structure which is easy to produce.

For this reason, when the internal fluid becomes a two-phase flow, there is a possibility that an abnormal heat transfer will occur due to a change in the amount of light collected and collected instantaneously, resulting in thermal damage at the site of the heat transfer tube.

Fresnel-type and trough-type concentrators / heat collectors are installed in a vast area with long heat transfer tubes arranged almost horizontally, and the amount of heat collected by sunlight varies greatly throughout the day. Also, it changes rapidly depending on the weather, and it is difficult to specify the range in which the two-phase flow flows in advance.

For this reason, it is necessary to make the heat transfer tube material high-performance, that is, an expensive material that is not easily damaged by heat, and there is a problem that the cost is increased.

(Fourth embodiment)
The fourth embodiment of the present invention is for solving such problems, and FIG. 14 is a schematic configuration diagram showing a use state in the second power generation mode of the combined power plant according to the fourth embodiment. FIG. 15 is a schematic configuration diagram showing a use state of the combined power plant in the first power generation mode. The configuration of the complex plant shown in FIGS. 14 and 15 is the same, but the devices used differ depending on the power generation mode as in the first embodiment.

In the case of this embodiment, as shown in FIG. 15, a water supply circulation flow rate control valve 37 for adjusting the circulation flow rate and a flow meter 28 are provided on the inlet side of the low-temperature heating device 13, and the water level for detecting the water level of the brackish water separator 4 A total of 29 is provided.

Then, the flow rate measurement signal of the flow meter 28 and the water level measurement signal of the water level meter 29 are input to the arithmetic device 26, and the arithmetic device 26 supplies water for adjusting the feed water flow rate so that the water level of the brackish water separator 4 becomes the target value. A control signal is output to the valve 19 or (and) the feed water circulation flow rate control valve 37 for adjusting the circulation flow rate.

By controlling the water level of the brackish water separator 4 as in this embodiment, it is possible to operate without causing phase separation in the heat transfer tube of the low-temperature heating device 13. This principle will be described with reference to FIGS. 16 and 17.

FIG. 16 is a characteristic diagram showing the relationship between the water level L (horizontal axis) of the brackish water separator 4 and the outlet quality X (vertical axis) of the low-temperature heating device 13, with the total mass flow rate G of the brackish water separator 4 as a parameter. The relationship between the water level L and the exit quality X is shown.

The outlet quality X of the low-temperature heating device 13 is the ratio of the mass flow rate of steam to the total mass flow rate G. Further, the total mass flow rate G of the brackish water separator 4 is a flow rate of fluid circulating through the low-temperature heating device 13 via the brackish water separator 4.

FIG. 17A shows the horizontal heat transfer pipe 38 (see FIG. 13) of the low-temperature heating device 13 with the horizontal axis representing the outlet quality X of the low-temperature heating device 13 and the vertical axis representing the total mass flow rate G of the brackish water separator 4. FIG. 2 is a diagram showing the regions of the two-phase flow of water-steam flow divided into a spray flow, an annular flow, a bubble flow, a slag flow, and a stratified flow state.
FIG. 17 (b) is a schematic diagram showing each flow state of the water-steam two-phase flow in the horizontal heat transfer tube 38. The states of the spray flow, the annular flow, the bubble flow, the slag flow and the stratified flow are shown in FIG. It is shown.

In FIG. 17 (b), the water-steam two-phase spray flow indicates a state in which most of the pipe is steam, and minute water droplets flow in the steam accompanying the steam. An annular flow forms a very thin water film on the tube wall, and the inside thereof indicates a state of a spray flow mainly composed of steam. The bubble flow indicates a state where most of the inside of the pipe is filled with water and small bubbles are present therein. The slug flow is considerably larger than the bubble flow, and indicates an intermediate state between the bubble flow and the stratified flow. A stratified flow indicates a state in which a gas phase and a liquid phase are vertically separated by the action of gravity.
Therefore, a preferable flow state of the water-steam two-phase flow in the horizontal heat transfer tube 38 is a spray flow or an annular flow.

As is apparent from the results of FIG. 16, it can be seen that there is a correlation between the water level L of the brackish water separator 4 and the outlet quality (ratio of the steam flow rate to the total mass flow rate) X of the low-temperature heating device 13. Thus, for example, in the mass flow rate G ₁ of the steam separator unit 4, by measuring the water level L ₁ of the steam separator unit 4, it is possible to obtain the exit quality X ₁ of the low temperature heating unit 13.

Next, as shown in FIG. 17A, if the outlet quality X of the low-temperature heating device 13 and the total mass flow rate G of the brackish water separator 4 are known, the flow of the water-steam two-phase flow in the low-temperature heating device 13 You can know the state. To describe the example shown in FIG. 16, in the conditions of the mass flow rate G _1, when water level in the steam separator unit 4 is in L _1, it can be seen the outlet quality is X _1.

In order to prevent phase separation in the horizontal heat transfer tube 38 of the low-temperature heating device 13, it is preferable that the flow state is a bubble flow, an annular flow or a spray flow over all operating conditions. In a high state, it is particularly desirable to use an annular flow or a spray flow.

As shown in FIG. 15, in the pipe of the low-temperature heating device 13 that is one-sided heating, when separated into two phases of water and steam as in the slag flow or stratified flow shown in FIG. Overheating, and undesirable events for stable operation of the power plant, such as high temperature creep and pipe deformation. Therefore, appropriately managing the flow state of the water-steam two-phase flow in the low-temperature heating device 13 is extremely important for stable operation of the power plant.

Therefore, in this embodiment, the water level target value of the brackish water separator 4 corresponding to the value of the outlet quality X that achieves a desired flow state as described above is stored in the arithmetic device 26 in advance. Then, the measurement signals of the flow rate of the flow meter 28 and the water level of the water level meter 29 are input to the calculation device 26, and the calculation device 26 adjusts the feed water flow rate so that the water level of the brackish water separator 4 becomes the target value. The control signal is output to the feed water circulation valve 19 or (and) the feed water circulation flow rate control valve 37 for adjusting the circulation flow rate, so that the power plant can be stably operated.

(Fifth embodiment)
The fifth embodiment of the present invention is also for solving the same problems as the fourth embodiment, and FIG. 18 shows the use state of the combined power plant according to the fifth embodiment in the second power generation mode. FIG. 19 is a schematic configuration diagram showing a use state of the combined power plant in the first power generation mode. The configuration of the complex plant shown in FIG. 18 and FIG. 19 is the same, but the equipment to be used differs depending on the power generation mode as in the first embodiment.

As shown in FIG. 19, the low-temperature heating device 51 and the light collecting / collecting device 52 are separated, and a heat medium flow channel 53 is attached to the light collecting / heat collecting device 52. A heat medium circulation pump 55 is provided. A part of the heat medium flow path 53 is arranged in the low temperature heating device 51 as a heat exchanger to form a low temperature heating device 51 with a heat exchanger, and the heat medium 54 is transferred from the light collecting / heat collecting device 52 to the heat medium. It is configured to circulate in the flow path 53.

Then, the heat collected by the condensing / heat collecting device 52 is transmitted to the low temperature heating device 51 through the heat medium 54 circulating in the heat medium flow path 53, and the water-vapor fluid in the low temperature heating device 51 is heated.

The heat exchanger in the low-temperature heating device 51 (in this embodiment, a part of the heat medium flow channel 53) is a non-contact between the heat medium 54 and the fluid composed of water-vapor in the low-temperature heating device 51. There is no particular limitation as long as it is a contact type.

In this embodiment, as the light collecting / heat collecting device 52, a light collecting device and a heat collecting device can be installed at a low position near the ground surface, such as a Fresnel type or trough type light collecting / heat collecting device. Is preferred.

As the heat medium 54, a heat medium that does not change phase in the operating temperature range is used, and the heat medium circulation pump 55 circulates the heat medium flow path 53 from the condensing / heat collecting device 52. As the heat medium 54, for example, a simple substance such as diphenyl oxide, biphenyl, 1, 1 diphenylethane, or a chemically synthesized oil blended can be used.

The maximum operating temperature of the exemplified heat medium 54 is about 400 ° C., and if it exceeds this, the performance is significantly deteriorated and lost. For this reason, strict temperature control is required, but as shown in FIG. 19, a heat medium thermometer 56 is attached to the heat medium flow path 53 to monitor the temperature of the outlet heat medium of the light collecting / heat collecting device 52. The temperature of the heat medium 54 is lower than the maximum use temperature, for example, regulated to 300 ° C. or less, so that it is not necessary to take special treatment within the operation range.

In this way, in the condensing / heat collecting device 52, the heat medium 54 does not change phase and does not become a two-phase flow. Therefore, thermal damage of the heat transfer tube is not caused even under uneven heat flux distribution conditions, and reliability can be improved and material cost can be reduced.

Further, the following configuration may be provided.
As shown in FIG. 19, a heat medium thermometer 56 and a heat medium flow meter 57 for measuring the temperature and flow rate of the heat medium 54 are provided on the outlet side of the light collecting / heat collecting device 52. Each measurement signal of the medium flow meter 57 is input to the arithmetic unit 26.

In the arithmetic unit 26, a control signal for controlling the opening of the water supply valve 20, that is, the water supply flow rate, is provided so that the outlet side heat medium temperature of the light collecting / heat collecting device 52 is 300 ° C. or less. To output.

The reason for restricting the outlet fluid temperature of the light collecting / heat collecting device 52 to 300 ° C. or lower is the same as that in the third embodiment, and thus a duplicate description is omitted. Further, since the other configuration is the same as that of the above-described embodiment, the overlapping description is omitted similarly.

In the fifth embodiment, the low-temperature heating device 51 uses solar heat for steam generation / heating indirectly through a heat medium heated by a separate condensing / heat collecting device 52, and the high-temperature heating device 14 uses other heat. As in the embodiment, the steam is directly heated by the concentrated and collected solar heat, and so-called hybrid heating type.

According to the fifth embodiment, the configuration and scale of the parts related to the circulation system of the heat medium, such as the heat exchanger and the heat medium circulation pump 55 that complicate the structure of the boiler device, are minimized, and the first The problem described at the beginning of the description of the fourth embodiment can be reliably suppressed and is effective.

(Sixth embodiment)
6th Embodiment of this invention is a more desirable form of the low-temperature heating apparatus 24 in the said 2nd Embodiment, eliminates the same problem as 4th Embodiment, reduces the power consumption of the circulation pump 15, and makes a plant It is an embodiment for stabilizing.

FIG. 20 is a schematic configuration diagram illustrating a usage state in the second power generation mode of the combined power plant according to the sixth embodiment, and FIG. 21 is a schematic diagram illustrating a usage state in the first power generation mode of the combined power plant. It is a block diagram. Although the configuration of the complex plant shown in FIG. 20 and FIG. 21 is the same, the equipment to be used differs depending on the power generation mode as in the first embodiment.

The difference from the second embodiment is that, as shown in FIG. 21, a plurality of low-temperature heating devices 24 comprising a trough-type or Fresnel-type condensing / heat collecting device (in this embodiment, the first low-temperature heating is used). The device 24a and the second low-temperature heating device 24b) are arranged in series along the feed water flow direction, and the second low-temperature heating device 24b on the downstream side in the feed water flow direction is the first low-temperature heating device 24a on the upstream side in the feed water flow direction. This is the point of using a heat collecting tube having a smaller inner diameter than that.
Other configurations and power generation mechanisms are the same as those in the second embodiment, and a duplicate description is omitted.

The purpose of this embodiment is to reduce the power consumption of the circulation pump 15 so as not to cause the separation of the two-phase flow in the heat collecting tube.

In the fourth embodiment, the upper limit value of the outlet quality of the low-temperature heating device 24 is set to approximately 0.4 to 0.6 under the condition of the tube inner diameter of about 100 mm so as not to cause separation of the two-phase flow in the tube. Since the evaporation amount is constant, setting the outlet quality of the low-temperature heating device 24 to a higher value of about 0.7 to 0.9 reduces the circulating flow rate of water and the power consumption of the circulation pump 15 There is a relationship of decline.

FIG. 22 is a flow pattern diagram of a gas-liquid two-phase flow in which the flow state of the gas-liquid two-phase flow in a general horizontal tube is separated by the flow mode and arranged according to the gas phase apparent velocity and the liquid phase apparent velocity in the tube. is there. In the figure, the horizontal axis represents the apparent velocity of the gas phase, and the vertical axis represents the apparent velocity of the liquid phase.

According to FIG. 22, if the apparent velocity of the gas phase and the liquid phase in the pipe is sufficiently large, even if the outlet quality of the low-temperature heating device 24 is high, the desirable pipe flow as described in the fourth embodiment. It is possible to operate in the areas of spray flow, bubble flow and annular spray flow which are modes.

The basic parameters of gas-liquid two-phase flow are shown below.
α = ρlx / {ρlx + ρg (1-x)} (1)
ρ = (1-α) ρl + αρg (2)
Vg = αV (3)
Vl = (1−α) V (4)
V = G / (ρA) (5)
Α void fraction in the equation, ρ1 is liquid phase density, x is vapor quality, ρg is gas phase density, ρ is average density of gas-liquid two-phase flow, Vg is gas phase apparent velocity, V is average velocity, V1 is liquid The apparent speed, G is the mass flow rate, and A is the cross-sectional area in the tube.

In order to increase the average flow velocity V of the fluid in the pipe, the circulation flow rate may be increased or the pipe inner diameter may be reduced. In the former case, the outlet quality of the low-temperature heating device is reduced as described above to reduce the power consumption of the circulation pump. However, in the latter case, the average flow velocity V is inversely proportional to the square of the tube inner diameter D due to the relationship between the tube cross-sectional area A and the tube inner diameter D expressed by Equation (6). The friction loss ΔP _{f in the} pipe expressed by is proportional to the square of the average flow velocity V.

^{A = πD 2/4 ··· (} 6)
ΔP _f / L = fρV ² / D (7)
In the equation, f is the in-tube two-phase fluid friction coefficient, and L is the tube length.

According to the above, when the average flow velocity V of the fluid in the pipe is increased by reducing the pipe inner diameter D with respect to a certain amount of evaporation, the two-phase separation is achieved even if the outlet quality of the low-temperature heating device is set higher than before. Will not occur.

In addition, although the friction loss in the pipe increases due to the increase in the average flow velocity V, it is not necessary that all the heat transfer pipes of the low-temperature heating apparatus have a single pipe inner diameter. In the second low temperature heating device 24b on the side, if a heat transfer tube having a smaller inner diameter than that of the first low temperature heating device 24a on the upstream side is used, the loss can be minimized and the circulation flow rate can be reduced. Thus, the power consumption of the circulation pump 15 can be reduced.

Hereinafter, a more specific example will be described with reference to FIG. In the figure, the mark ● indicates the first low-temperature heating device 24a on the upstream side, and the mark ○ indicates the second low-temperature heating device 24b on the downstream side.

In Comparative Example 1 shown in FIG. 22, the tube inner diameters of the first low temperature heating device 24a on the upstream side and the second low temperature heating device 24b on the downstream side are set to the same value of 100 mm, and the first low temperature heating device on the upstream side The outlet quality of the heating device 24a is 0.4 to 0.6, and the outlet quality of the second low temperature heating device 24b on the downstream side is 0.8 to 1.0. Under these conditions, it can be seen that the flow pattern in the pipe reaches a level that can become a problem after a certain region.

In Comparative Example 1, since the flow state in the pipe becomes a wave-like flow, saturated water and steam regions are formed separately in the pipe circumferential direction. The steam region has a small heat and heat transfer coefficient, which causes a problem in that the temperature rises locally. Specifically, the high temperature side of the heat transfer tube expands (extends), the low temperature side contracts, and the heat transfer tube is damaged by the difference. Moreover, the glass tube installed in the outer peripheral portion of the heat transfer tube is broken or cracked, and the temperature increasing portion is deformed.

In addition, the annular spray flow in the figure indicates a region including the annular flow and the spray flow described in the fourth embodiment. The wavy flow is a flow in which saturated water flows at the bottom of the tube and steam flows at the top of the tube, and the interface of the saturated water is rippled.

In Comparative Example 2 shown in FIG. 22, the tube inner diameters of the first low temperature heating device 24a on the upstream side and the second low temperature heating device 24b on the downstream side are set to the same value of 80 mm, and the first low temperature heating device on the upstream side is used. The outlet quality of the heating device 24a is 0.4 to 0.6, and the outlet quality of the second low temperature heating device 24b on the downstream side is 0.8 to 1.0. Under this condition, it can be seen that there is no problem in the flow mode in the pipe over the entire area, but the inner diameter of the first low-temperature heating device 24a and the second low-temperature heating device 24b on the wake side is 80 mm. Is not preferable.

On the other hand, in the present invention, the tube inner diameter of the first low temperature heating device 24a on the upstream side is 100 mm, the outlet quality is 0.4 to 0.6, and the tube inner diameter of the second low temperature heating device 24b on the downstream side is set. 80mm, exit quality is 0.8-1.0. Under this condition, it can be seen that there is no problem in the flow mode in the pipe from the inlet to the outlet, and the pipe friction loss is also kept low.

By the way, as described in the third embodiment, as shown in FIG. 13, the trough-type condensing and heat collecting apparatus is a double tube in which an inner tube is constituted by a heat transfer tube 38 and an outer tube is constituted by a glass tube 42. The structure is a so-called vacuum tube type light collecting / collecting device, in which the gap between the inner tube and the outer tube is used in a vacuum.

When the trough-type condensing / collecting device is used in the low-temperature heating apparatus configured as described above, the condensing loss increases as the diameter of the heat transfer tube decreases due to the trough concentrating / collecting principle. Cause problems.

Due to this problem, when the desired heat transfer tube length steam quality cannot be obtained with the conventional heat transfer tube length, the fins are attached to some or all of the outer periphery of the tube over the entire length of the small diameter heat transfer tube. A decrease in light efficiency can be suppressed.

Also, the use of finned tubes does not significantly increase costs compared to measures such as the use of high-precision condenser mirrors or an increase in the number of mirrors.

For example, in Patent Document 3, a heat pipe is used in a vacuum tube type solar heat collector, and a fin is attached outside the heat pipe, and a fin is attached to a heat transfer tube used in a solar heat collecting / collecting device. And a structure in which the surface of the heat pipe is coated with a high emissivity material or a selective absorption film to improve the light collection and heat collection efficiency. Patent Document 4 discloses a structure in which fins are provided on the inner surface of a heat transfer tube of a solar heat collector to reduce the temperature difference between the front and back surfaces of the heat transfer tube.

The present embodiment is a vacuum tube type condensing / collecting device in the second low-temperature heating device 24b on the downstream side where the steam quality is increased, and the heat transfer of the second low-temperature heating device 24b, which is a problem peculiar to the above configuration. Adopted to prevent a decrease in light collection efficiency due to a decrease in the light receiving surface when the tube diameter is reduced, and it is desirable to coat a high emissivity material or a selective absorption film on the fin surface and the heat transfer tube surface in order to promote radiant heat transfer.

The fins are attached to all or part of the outer circumference of the heat transfer tube, and there are a structure in which the fin ribbon is wound around the tube, a structure in which the fin plate is welded to the tube length, a structure in which the fin is processed into a saw shape, etc. It is desirable to have a structure that increases.

As the high emissivity material, for example, a silicon-based paint can be used. As the selective absorption film, for example, nickel-black nickel, tungsten, or the like can be used.

(Seventh embodiment)
FIG. 23 is a schematic configuration diagram of a solar thermal power plant according to the seventh embodiment.
As shown in the figure, a plurality of low-temperature heating devices 24 (first low-temperature heating device 24a and second low-temperature heating device 24b in this embodiment) composed of a trough-type or Fresnel-type light collecting / collecting device are used to supply water. They are arranged in series along the flow direction.

This solar thermal power plant includes a first low-temperature heating device 24a on the upstream side that heats water supplied from the feed water pump 11 with the heat of sunlight 32, a second low-temperature heating device 24b on the downstream side, and a first low-temperature heating device. The brackish water separation device 4 that separates the mixed fluid of water and steam generated by the heating device 24a and the second low temperature heating device 24b into water and steam, and the steam separated by the brackish water separation device 4 is heated by the heat of sunlight 32. High-temperature heating device 14, circulation pump 15 that supplies water separated by brackish water separation device 4 to low-temperature heating device 24, circulation flow rate control valve 37 for controlling the circulation flow rate, and high-temperature steam generated by high-temperature heating device 14 And a generator 67 that generates electric power by being rotated by the steam turbine 68, and has a connection relationship as shown in the figure.

Also in this embodiment, the inner diameter of the heat transfer tube of the second low-temperature heating device 24b on the downstream side is made smaller than the inner diameter of the heat transfer tube of the first low-temperature heating device 24a on the front flow side, or further, 2 Fins can be provided on the outer periphery of the heat transfer tube over the entire length of the heat transfer tube of the low-temperature heating device 24b, and the fin surface and the heat transfer tube surface can be coated with a high emissivity material or a selective absorption film.

In the sixth embodiment and the seventh embodiment, two low-temperature heating devices are arranged in series. However, three or more low-temperature heating devices can be arranged in series as necessary.
As the feed water heater 12 used in each of the above-described embodiments, one having a configuration in which the feed water is heated by a heat medium such as steam is used, but the feed water heater 12 is also configured to heat the feed water using solar heat. Is also possible.

In each of the above embodiments, water heated by the feed water heater 12 is introduced into the brackish water separator 4, but water from the feed water pump 11 can also be directly introduced into the brackish water separator 4.

As described above, by installing the low-temperature heating device and the brackish water separation device on or near the ground surface, the present invention eliminates the need for a structure (for example, a support base) that supports a heavy object that holds saturated water, A structure that is low and easy to install and maintain the low-temperature heating device and the brackish water separator is sufficient. Further, it is possible to simplify the structure for installing a relatively lightweight high-temperature heating apparatus that holds only steam at a high place.

Furthermore, the risk of damage to the heat transfer tube can be reduced by functionally separating the low temperature heating device and the high temperature heating device and installing a brackish water separation device between them.
Further, by installing the high temperature heating device at a high place, heat exchange with high heat density is possible, and high temperature steam can be obtained efficiently.
Furthermore, it is possible to keep the output of the steam turbine constant by adjusting the amount of extracted steam on the steam turbine side in accordance with fluctuations in the steam temperature and steam flow when the heat collection amount is controlled by the high-temperature heating device. Become.

4: Brackish water separator,
6: Heliostat,
7: the sun,
8: Steam turbine,
9: Generator,
10: boiler plant,
10a: reheat steam heat exchanger,
10b: main steam heat exchanger,
11: Water supply pump,
12: Feed water heater,
13: Low temperature heating device,
14: High temperature heating device,
15: Circulation pump,
16: Tower,
17: Extraction valve,
18: Steam valve,
20: Solar water supply valve,
21: Superheater heat transfer tube,
24: Low temperature heating device,
24a: first low-temperature heating device,
24b: second low-temperature heating device,
25: Thermometer,
26: arithmetic device,
27: Heat transfer tube panel,
28: Flow meter,
30, 35: Condensing mirror,
31: Heat transfer tube,
32: Sunlight,
33: Water
34: Water-steam two-phase flow 37: Circulation flow control valve,
38: Horizontal heat transfer tube,
51: Low temperature heating device,
52: Condensing / heat collecting device,
53: Heat medium flow path,
54: Heat medium,
55: Heat medium circulation pump,
56: Heat medium thermometer,
57: Heat medium flow meter 60: High-pressure steam turbine,
61: Medium pressure steam turbine,
62: low pressure steam turbine,
64: Generator for high-pressure steam turbine,
65: Medium / low pressure steam turbine generator,
66: Thermal power supply valve,
67: Generator,
68: Steam turbine.

Claims (13)

1. A first power plant that collects solar heat and generates steam with the heat;
   A second power plant that generates steam by burning or generating heat, or recovering heat of exhaust gas;
   A combined power plant comprising a steam turbine that rotates by introducing steam generated in the first power plant or the second power plant, and a generator that is rotationally driven by the steam turbine,
   The first power plant is
   A low-temperature heating device provided with a horizontal heat transfer tube for heating water supplied from a water supply pump by the solar heat;
   A brackish water separator that separates the water-steam two-phase flow generated by the low-temperature heating device into water and steam;
   A high-temperature heating device that superheats the steam separated by the brackish water separator with solar heat,
   A circulation pump for supplying water separated by the brackish water separator to the low-temperature heating device;
   The second power plant is
   A steam generator having a reheat steam heat exchanger and a main steam heat exchanger for generating steam;
   A water supply pump for supplying water to the steam generator;
   A water heater for heating the water supplied by the water supply pump with the extracted steam from the steam turbine;
   The steam turbine includes a high pressure steam turbine, an intermediate pressure steam turbine, and a low pressure steam turbine,
   In the first power generation mode in which power generation is performed using the first power plant, the steam superheated by the high-temperature heating device of the first power plant is guided to the intermediate pressure steam turbine and the low pressure steam turbine to generate power,
   In a second power generation mode in which power generation is performed using the second power plant, steam superheated by the main steam heat exchanger of the second power plant is transferred to the high-pressure steam turbine, intermediate-pressure steam turbine, and low-pressure steam turbine. A combined power plant characterized in that it is configured to guide and generate electricity.
2. In the combined power plant according to claim 1,
   The combined power generation characterized in that the low temperature heating device, the brackish water separation device and the circulation pump are installed on the ground surface or near the ground surface, and the high temperature heating device is installed at a higher position than the low temperature heating device and the brackish water separation device. plant.
3. In the combined power plant according to claim 1,
   The low temperature heating device is:
   A heat transfer tube is arranged above the inner peripheral curved surface of the condensing mirror extending in a bowl shape, and the sunlight is condensed on the heat transfer tube by the condensing mirror, thereby heating the water circulating in the heat transfer tube to steam. A large number of trough-type condensing / heat collecting devices or substantially planar collecting mirrors are arranged, a heat transfer tube is arranged above the collecting mirror group, and the sunlight is transmitted through the collecting mirror group. It consists of a Fresnel-type condensing / collecting device that heats the water flowing through the heat transfer tube to produce steam by condensing it on the heat tube,
   The high temperature heating device is:
   A heat transfer tube panel is installed on a tower having a predetermined height, a large number of condensing mirrors are arranged, and sunlight is condensed on the heat transfer tube panel by the condensing mirror group. A combined-type power plant comprising a tower-type light collecting and collecting device that superheats the steam flowing through the steam generator to generate superheated steam.
4. In the combined power plant according to claim 1,
   A combined power plant characterized in that an outlet fluid temperature of the low-temperature heating device is regulated to 300 ° C or lower.
5. In the combined power plant according to claim 4,
   A thermometer is installed on the outlet side of the low-temperature heating device, and the feed water flow rate to the low-temperature heating device is adjusted so that the fluid temperature measured by the thermometer is 300 ° C. or lower. A featured combined power plant.
6. In the combined power plant according to claim 4,
   A thermometer is installed on the outlet side of the low-temperature heating device, and the heat collection amount of the low-temperature heating device is adjusted so that the fluid temperature measured by the thermometer is 300 ° C. or less. A combined power plant.
7. In the combined power plant according to claim 1,
   A thermometer and a flow meter are installed on the outlet side of the low-temperature heating device, and the amount of heat collected by the high-temperature heating device is adjusted according to the temperature and flow rate values measured by the thermometer and the flow meter. A combined power plant characterized by
8. In the combined power plant according to claim 1,
   A water level meter for measuring the water level of the brackish water separator, a water supply valve for adjusting the feed water flow rate to the low temperature heating device, and a circulation flow rate control for adjusting the amount of water circulating between the low temperature heating device and the brackish water separator A valve,
   A combined power plant, wherein the feed water flow rate or the circulation rate is adjusted by the feed water valve or the circulation flow rate control valve so that the water level of the brackish water separator becomes a predetermined value.
9. In the combined power plant according to claim 1,
   The low temperature heating device is:
   A heat medium flow path through which the heat medium circulates;
   A heat medium circulation pump provided in the middle of the heat medium flow path;
   A light collecting / collecting device that is provided in the middle of the heat medium flow path and transmits heat generated by collecting sunlight to the heat medium circulating in the heat medium flow path;
   A part of the heat medium flow path comprises a low-temperature heating device with a heat exchanger installed inside as a heat exchanger,
   A combined power plant configured to transmit heat collected by the condensing / heat collecting device to water in the low-temperature heating device with the heat exchanger via the heat medium.
10. In the combined power plant according to claim 1,
    An extraction valve is provided on the outlet side of any one of the high-pressure steam turbine, intermediate-pressure steam turbine, and low-pressure steam turbine,
    A combined power plant, wherein the extraction valve is operated according to the amount of steam supplied from the high-temperature heating device to adjust the amount of extraction of the steam.
11. In the combined power plant according to claim 3,
    The low-temperature heating device includes at least a first low-temperature heating device disposed on the upstream side in the water flow direction and a second low-temperature heating device disposed on the downstream side in the water flow direction of the first low-temperature heating device. Prepared,
    The combined power generation characterized in that the flow velocity of the fluid flowing in the heat transfer tube of the second low-temperature heating device is faster than the flow velocity of the fluid flowing in the heat transfer tube of the first low-temperature heating device. plant.
12. The combined power plant according to claim 11,
    A combined power plant characterized in that the inner diameter of the heat transfer tube of the second low-temperature heating device is smaller than the inner diameter of the heat transfer tube of the first low-temperature heating device.
13. The combined power plant according to claim 11 or 12,
    A combined power plant, wherein fins are provided over the entire length of the heat transfer tube of the second low-temperature heating device.

Images