JP2001201187A - Solar heat boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar heat boiler which has a small-sized and simple structure and high efficiency. SOLUTION: A heat collecting tube, through which a heat receiving fluid flows, is disposed fixed on the focal axis of ranging focuses of a parabolic reflector formed like a trough and in a long shape. The parabolic reflector is supported axially and rotatably around the axis of rotation coinciding with the focal axis, and besides, a sun follower is connected coaxially to the parabolic reflector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler for solar thermal power generation in which a light-receiving surface is always directed toward the sun by a sun tracking device.

[0002]

2. Description of the Related Art Today, photovoltaic power generation, which directly converts sunlight into electricity by means of solar cells, is the mainstream of solar energy utilization. Usually, it is installed as a non-focus type in which solar cells are laid like a tile on the roof of a house or the like. The government is subsidizing this type of power generator for home use, but the low energy conversion efficiency of solar cells (about 10% for polycrystalline silicon) and the high cost (10 10,000 yen / m ² ) is a problem.

[0003] Low conversion efficiency leads to a large installation area requirement. For example, the average household annual power consumption is about 4,50
0 kWh, 60-80% or 3,000-3.5
To generate 00 kWh, a photovoltaic power generation system with an output of 3 kW is required, and the installation area of the system (in the case of a sloping roof) is about 26 m ² (from M company's business materials). From this, it can be seen that the equipment cost is several million yen, but the subsidy is one third of that.

[0004] Another possibility is solar thermal power generation. This produces steam from solar heat, which turns turbines and generators. In the wake of the oil crisis, a large-scale test facility of this kind was built in Niio Town, Kagawa Prefecture, as part of the Sunshine Project in Japan.

[0005] In this facility, a solar heat boiler provided at the top of the central tower collects sunlight with a large reflector with a large number of sun tracking devices (heliostats) to generate steam, and the steam is used to generate turbines and generators. Was to turn. However, in addition to the fact that it was difficult to keep the reflecting mirror surface clean at all times, the efficiency decreased, and in addition to the fact that a large amount of power was required to drive a large number of heliostats, it was not possible to extract power beyond the payline to the outside. Can be Since the facility was shut down after three years of operation, Japan's solar thermal power generation has virtually stopped.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a small-sized, simple-structure, and high-efficiency solar boiler. By supplying steam from such a solar boiler and turning a turbine / generator, a small-scale household solar thermal power generation system can be easily realized. The reason for home use is to solve the difficulties experienced in large solar thermal power generation facilities in the past by reducing the size and decentralization of the facilities.

[0007]

An object of the present invention is to provide a trough-shaped parabolic reflector, in which a heat-collecting tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points thereof. This is achieved by a solar boiler which is rotatably supported around a rotation axis coinciding with the focal axis, and in which a sun tracking device is coaxially connected to a parabolic reflector.

The main body of the solar boiler is a heat collecting tube. While a heat-receiving fluid such as water flows through the inside, it is heated by the solar heat applied to the heat collection tube to be turned into steam. This steam is supplied to a power generation turbine. The tube wall of the heat collection tube is a transparent double wall with a vacuum inside in order to efficiently capture solar heat and provide heat insulation that does not allow the captured heat to escape to the outside. Further, the heat receiving fluid reciprocates through the U-shaped tube inserted into the heat collecting tube, and heat is exchanged between the inlet and outlet heat-receiving fluids of the U-shaped tube to average the temperatures, thereby reducing heat loss.

The heat collecting tube is fixed to the center (on the focal axis) of the solar boiler, and a long trough-shaped parabolic reflecting mirror collects the sunlight rays from the heat collecting tube. The parabolic reflector is driven by a sun tracking device to be described later so that the center of curvature of the mirror surface always faces the sun. In order for this movement to be performed correctly, the inclination of the focal axis of the heat collection tube, that is, the parabola reflector, must be adjusted so that the projection line on the ground surface is oriented exactly to the north, and the solar rays are directed perpendicular to the heat collection tube. Must. This adjustment may be made every few days. In this way, the position of the sun moving every moment due to the rotation of the earth can be automatically tracked by the sun tracking device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this solar boiler, a measure is taken at low cost to avoid the difficulty of maintaining and maintaining the mirror surface, which has been experienced with a large reflector in the past. For this reason, the size of the parabolic reflecting mirror is set to a size that can easily wipe off dust adhering to the mirror surface with a small number of hands. From there,
The mirror surface dimension of a scale suitable for home use, which does not exceed approximately 1 m × 2 m, and the boiler capacity associated therewith are determined. In order to prevent dust from adhering to the mirror surface, a mirror surface protection door is provided at the end of the parabolic reflector, and the door is closed when the reflector is not used. In that case, the door should be lightweight so that it can be opened and closed manually. The inner surface of the protective door may be made a mirror surface so as to substantially increase the area of the parabolic reflector when the door is opened.

The above-described solar tracking device includes a solar cell panel having a pair of same-sized and same-sized solar cells arranged symmetrically in contact with an output shaft thereof, and a solar cell panel vertically extending from the output axis to a light receiving surface of the solar cell panel. The solar cell panel is rotated around the output shaft in a direction to make the power generation output difference substantially zero, being energized according to the power generation output difference between the left and right solar cells and the thin flat light shielding plate protruding And a motor that drives the motor. The sun tracker is coaxially connected to a parabolic reflector. That is, the output shaft of the sun tracking device is directly connected to the rotation axis of the parabolic reflector, or both are connected in parallel so as to rotate in the same direction at the same angle.

If the solar cell panel in this sun tracking device is compared to the horizontal tail of an airplane, the light shielding plate corresponds to the vertical tail. When the solar panel faces the sun, the light shielding plate does not create a shadow on the solar cell surface, so that the outputs of the left and right solar cells are balanced, and the motor connected to this does not rotate. If the photovoltaic panel deviates from the facing relationship, the shading plate will create a shadow on one of the photovoltaic surfaces, causing the output of the photovoltaic cell to become unbalanced and the motor to rotate. In this case, since the motor is connected so as to rotate in a direction to reduce the unbalance of the solar cell output, the solar cell panel surface tracks the sun and recovers the facing relationship. In addition,
Both surfaces of the light shielding plate may be mirror surfaces. By reflecting the light hitting the light-shielding plate to the solar cell surface, there is an effect that the imbalance of the solar cell output is emphasized and the tracking sensitivity is increased.

If this solar tracking device accidentally faces the opposite direction to the sun, the left and right solar cells are aligned and lose their output, so that the motor does not rotate and the tracking function is lost. In order to eliminate this weak point, a third solar cell may be provided on the back surface of the solar cell panel, and its output may be connected to a motor. When this sun tracking device is directed in the opposite direction to the sun and shines on the third solar cell, the motor rotates until its output becomes zero, so the surface of the solar cell panel faces the sun and the tracking function is performed. To be resurrected.

This sun tracking device is self-sufficient in driving force because it incorporates a solar cell as a solar sensor and power source. Therefore, since power supply to the sun tracking device is not required, a situation in which a large power generation output is consumed internally and cannot be taken out, as experienced in a facility in Nio-cho, is avoided. In addition, a small solar cell used for this solar tracking device is sufficient. This is because the sun tracking operation is extremely slow and the rotation of the motor is reduced at a sufficiently large gear ratio, so that a desired torque can be obtained even when the solar cell current is small.

[0015]

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view for explaining the structure of a solar boiler as an embodiment, FIG. 2 is an explanatory view of a heat collecting tube and a U-shaped tube inserted therein, and FIG. 3 is a diagram showing a solar cell included in this solar boiler. FIG. 4 is a conceptual piping diagram showing a turbine / generator system including the solar boiler.

In FIG. 1, a solar boiler 1 rotatably supports a trough-shaped long parabolic reflecting mirror 4 around a rotating shaft 21-21 on a gantry 2 so as to rotate freely. It is fixedly arranged at the position of the rotating shaft 21-21, and
The output shaft of the sun tracking device 5 fixed to the
It is configured to be directly connected to the rotating shaft of.

While a heat-receiving fluid such as water flows through the heat collecting tube 3, it is heated by the solar heat condensed on the heat collecting tube 3 by the parabolic reflecting mirror 4 to become steam. Reference is now made to FIG. The tube wall of the heat collecting tube 3 is composed of a transparent double wall 31 whose inside is evacuated, and the heat receiving fluid reciprocates through a U-shaped tube 32 inserted into the heat collecting tube 3 to enter and exit the U-shaped tube at the entrance / exit 33, 34. Are exchanged between the heat receiving fluids and the temperatures are averaged.

Returning to FIG. The parabolic reflecting mirror 4 is driven by the sun tracking device 5 so that the center of curvature of the mirror surface is always directed to the sun. In order to realize this movement,
The center line of the bottom is directed to the north, and the inclination of the gantry 2 (the arc-shaped arrow in FIG. 1) is adjusted so that the solar rays hit the heat collecting tube 3 at right angles. Since the adjustment of the inclination is an adjustment for seasonal changes in the height of the sun, it is sufficient to manually perform the adjustment every few days. Then, the sun tracking device 5 automatically tracks the position of the sun moving every moment due to the rotation of the earth, and the parabolic reflecting mirror 4 interlocked with the sun tracking device 5 automatically collects the heat collecting tube 3.
Can be collected.

The mirror surface of the parabolic reflector 4 and the surface of the heat collecting tube 3 are manually cleaned to keep them always clean. The size of the parabolic reflector 4 is at most 1 m × 2 m so that this operation can be performed with a small number of hands. Further, the mirror surface of the parabolic reflecting mirror 4 is divided into a central portion 41 and both side portions 42 and 43, and the widths thereof are １ ／, ４ and １ ／. Both side parts 42 and 43 are used as mirror surface protection doors so that they can be folded toward the central part 41. If the parabolic reflector 4 is closed when not in use, the surface of the reflector and the surface of the heat collecting tube can be protected from dust.

The sun tracking device 5 includes a pair of same-shaped and same-sized solar cells 51 arranged symmetrically in contact with the output shaft 56 thereof.
52, a thin flat light-shielding plate 54 protruding from the output shaft 56 vertically upward of the light receiving surface of the solar cell panel 50, and left and right solar cells 51 and 52.
And a motor 55 that is energized in accordance with the power generation output difference and rotates the solar cell panel 50 around the output shaft 56 in a direction to make the power generation output difference substantially zero. A third solar cell 53 is attached to the back surface of the solar cell panel 50, and its output is also connected to the motor 55. Motor 55
Is fixed on the gantry 2, and the shaft of the motor 55 and the output shaft 56 are connected via a reduction gear 57 composed of large and small gears,
The output shaft 56 is directly connected to the rotation shaft of the parabolic reflector 4.

When the solar cell panel 50 faces the sun, the light shielding plate 54 does not create a shadow on the solar cell surface, so that the outputs of the left and right solar cells 51 and 52 are balanced, and the motor 55 connected to this rotates. do not do. If solar panel 5
When 0 deviates from the facing relationship, the light shielding plate 54 creates a shadow on one of the solar cell surfaces, so that the outputs of the solar cells 51 and 52 become unbalanced and the motor 55 rotates. In this case, since the motor 55 is connected so as to rotate in a direction to reduce the unbalance of the solar cell output, the surface of the solar cell panel 50 tracks the sun and recovers the facing relationship. Both surfaces of the light-shielding plate 54 are mirror surfaces, and the light hitting the light-shielding plate 54 is reflected to the solar cell surface, thereby enhancing the imbalance of the solar cell output and increasing the tracking sensitivity.

When the solar cell panel 50 faces in the direction opposite to the sun, the third solar cell 53 is exposed to sunlight, and the power generation output causes the motor 55 to rotate. Third
While the solar cell 53 continues to output the output voltage,
Continues rotating, the solar cell panel 50 eventually faces the sun, and the normal solar tracking operation is restored.

FIG. 3 is a connection diagram showing a connection relationship between each of the solar cells 51, 52, 53 and the motor 55. Each solar cell is shown as a diode. Solar cells 51 and 52
Are connected to the motor 55 with their polarities reversed. The polarity of the solar cell 53 is arbitrary, but may be the same as the solar cell 51, for example. The direction of rotation of the motor 55 must be such that the difference between the power generation outputs of the solar cells 51 and 52 is reduced. If the motor 55 rotates in the opposite direction, the polarity of the connection terminal of the motor is reversed.

FIG. 4 is a conceptual piping diagram showing a turbine / generator system including the solar boiler 1. In the figure, steam flowing out of an outlet 34 of a heat collecting tube 3 of a solar boiler 1 is supplied to a turbine 7 via a stop valve 6. The rotational output of the turbine 7 is supplied to a generator 9 via a speed reducer 8. The exhaust gas of the turbine 7 enters the condenser 10 and is cooled by cooling water to be condensed. The condensed water is pumped up by the pump 11 and returns to the inlet 33 of the heat collecting tube 3.

[0025]

According to the present invention, there is provided a small-sized, simple-structure, and high-efficiency solar thermal boiler that can easily construct a small-scale household solar thermal power generation system.

In particular, in this solar boiler, a long trough-shaped parabolic reflector is driven by a self-sufficient solar tracking device having a built-in small-sized solar cell to collect solar rays into a heat collecting tube. The structure that does not dissipate the generated heat allows the solar energy to be used efficiently and almost all of the power generation output other than the power for the pump to be taken out.

Also, by adopting an apparatus size and structure that can easily keep the mirror surface of the parabolic reflector and the surface of the heat collecting tube clean, problems with clean maintenance experienced in past large-scale solar thermal power generation equipment are reduced. The cost has been solved.

[0028]

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating the structure of a solar boiler as an embodiment.

FIG. 2 is an explanatory view of a heat collecting tube and a U-shaped tube inserted therein.

FIG. 3 is a connection diagram of a solar cell and a motor included in the solar boiler.

FIG. 4 is a conceptual piping diagram showing a turbine / generator system including a solar boiler.

[Explanation of symbols]

 1: Solar boiler 2: Stand 3: Heat collecting tube 4: Parabolic reflector 5: Sun tracking device 6: Stop valve 7: Turbine 8: Reduction gear 9: Generator 10: Condenser 11: Pump

Claims (13)

[Claims] 1. A heat collection tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points of a long trough-shaped parabolic reflector, and the parabolic reflector is turned at a time corresponding to the focal axis. A solar boiler rotatably supported around a moving axis, and a sun-tracking device coaxially connected to the parabolic reflector, wherein the parabolic reflector is openable and closable at its mirror end. A mirror surface protection door provided, wherein a tube wall of the heat collection tube is formed of a transparent double wall having an interior vacuum, and the heat receiving fluid reciprocally flows through a U-shaped tube provided in the heat collection tube, and the sun tracking is performed. A solar cell panel having a pair of same-shaped and same-sized solar cells arranged symmetrically in contact with the output shaft of the device, and a thin flat plate protruding from the output shaft to a direction vertically above the light receiving surface of the solar cell panel; According to the power generation output difference between the right and left solar cells A motor that is energized and rotates the solar cell panel around an output shaft in a direction to make the power generation output difference substantially zero, wherein both surfaces of the light shielding plate are mirror surfaces, and the sun tracking device is And a third solar cell on the back surface of the solar cell panel, wherein the motor is energized also by the power output from the third solar cell, and the power output of the third solar cell becomes substantially zero. A solar boiler characterized by rotating a solar cell panel around an output shaft up to that point. 2. A heat-collecting tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points of a long trough-shaped parabolic reflector, and the parabolic reflector is rotated by a time corresponding to the focal axis. A solar boiler rotatably supported around a moving axis, and a sun-tracking device coaxially connected to the parabolic reflector, wherein the parabolic reflector is openable and closable at its mirror end. A mirror surface protection door provided, wherein a tube wall of the heat collection tube is formed of a transparent double wall having an interior vacuum, and the heat receiving fluid reciprocally flows through a U-shaped tube provided in the heat collection tube, and the sun tracking is performed. A solar cell panel having a pair of same-shaped and same-sized solar cells arranged symmetrically in contact with the output shaft of the device, and a thin flat plate protruding from the output shaft to a direction vertically above the light receiving surface of the solar cell panel; According to the power generation output difference between the right and left solar cells A motor that is energized to rotate the solar cell panel around an output shaft in a direction to make the power generation output difference substantially zero, further comprising a third solar tracking device on a back surface of the solar cell panel. A solar cell, wherein the motor is also energized by the power output from the third solar cell and moves the solar panel around the output axis until the power output of the third solar cell is substantially zero. A solar boiler characterized by rotating. 3. A heat-collecting tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points of a long trough-shaped parabolic reflector, and the parabolic reflector is rotated by a turn corresponding to the focal axis. A solar boiler rotatably supported around a moving axis, and a sun-tracking device coaxially connected to the parabolic reflector, wherein the parabolic reflector is openable and closable at its mirror end. A mirror surface protection door provided, wherein the tube wall of the heat collection tube is formed of a transparent double wall having an interior evacuated, and the sun tracking device is in contact with its output shaft and is symmetrically arranged in a pair of the same shape. A solar cell panel having a large solar cell, a thin flat light-shielding plate projecting vertically from the output shaft to the solar cell panel light-receiving surface, and biased according to the power generation output difference between the left and right solar cells. The solar cell in a direction to make the power generation output difference substantially zero. A motor for rotating the panel around an output shaft; and the sun tracking device further includes a third solar cell on a back surface of a solar cell panel, wherein the motor generates electric power from the third solar cell. A solar boiler which is energized by the output and rotates the solar cell panel around an output shaft until the power output of the third solar cell becomes substantially zero. 4. A heat collecting tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points of a long trough-shaped parabolic reflecting mirror, and the parabolic reflecting mirror is rotated by a time corresponding to the focal axis. A solar boiler rotatably supported around a moving axis, and a sun-tracking device coaxially connected to the parabolic reflector, wherein the parabolic reflector is openable and closable at its mirror end. A mirror surface protection door provided, wherein the tube wall of the heat collection tube is formed of a transparent double wall having an interior evacuated, and the sun tracking device is in contact with its output shaft and is symmetrically arranged in a pair of the same shape. A solar cell panel having a large solar cell, a thin flat light-shielding plate projecting vertically from the output shaft to the solar cell panel light-receiving surface, and biased according to the power generation output difference between the left and right solar cells. The solar cell in a direction to make the power generation output difference substantially zero. Solar boiler and having a motor for rotating the panel about the output shaft. 5. A heat-collecting tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points of a long trough-shaped parabolic reflector, and the parabolic reflector is rotated by a turn that coincides with the focal axis. A solar boiler rotatably supported around a moving axis, and a sun-tracking device coaxially connected to the parabolic reflector, wherein the parabolic reflector is openable and closable at its mirror end. A solar panel having a pair of same-sized and same-sized solar cells arranged symmetrically in contact with the output shaft thereof, and a solar cell panel receiving light from the output shaft. A thin flat light-shielding plate protruding vertically upward from the surface, and a solar cell panel that is energized in accordance with a difference in power generation output between the left and right solar cells and outputs the power generation output difference substantially to zero. Having a motor to rotate about an axis. Solar boiler and butterflies. 6. A heat collection tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points of a long trough-shaped parabolic reflector, and the parabolic reflector is rotated by a turn that coincides with the focal axis. A solar boiler rotatably supported around a moving axis, and having a sun tracking device coaxially connected to the parabolic reflector, wherein the sun tracking device is in contact with its output shaft and is left and right. A solar cell panel having a pair of symmetrically arranged same-sized and same-sized solar cells, a thin flat light-shielding plate protruding from the output shaft vertically upward of the solar cell panel light-receiving surface, and left and right solar cells And a motor which is energized in accordance with the power generation output difference and rotates the solar cell panel around an output shaft in a direction to make the power generation output difference substantially zero. 7. A heat collecting tube through which a heat-receiving fluid flows is fixedly arranged on a focal axis connecting the focal points of a long trough-shaped parabolic reflecting mirror, and the parabolic reflecting mirror is rotated by a time corresponding to the focal axis. A solar heat boiler rotatably supported around a moving axis and having a sun tracking device coaxially connected to the parabolic reflector. 8. The solar boiler according to claim 2, wherein both surfaces of said light shielding plate are mirror surfaces. 9. A solar boiler according to claim 3, wherein said heat receiving fluid reciprocates in a U-shaped tube provided in said heat collecting tube. 10. The solar tracking device has a third solar cell on a back surface of a solar cell panel, and the motor is also energized by a power output from the third solar cell, and the third solar cell The solar thermal boiler according to any one of claims 4 to 7, wherein the solar cell panel is rotated around an output shaft until the power generation output of the solar battery panel becomes substantially zero. 11. The solar heat boiler according to claim 5, wherein a wall of the heat collecting tube is a transparent double wall whose inside is evacuated. 12. The solar heat boiler according to claim 6, wherein said parabolic reflector has a mirror surface protective door provided at the mirror surface end so as to be openable and closable. 13. A solar cell panel comprising: a pair of same-sized and same-sized solar cells arranged symmetrically in contact with an output shaft of the solar tracking device; and a vertically above a light receiving surface of the solar cell panel from the output shaft. A thin flat light-shielding plate projecting toward the solar cell panel is energized according to the power generation output difference between the left and right solar cells and the solar cell panel is rotated around the output shaft in a direction to make the power generation output difference substantially zero. The solar heat boiler according to claim 7, further comprising a motor for rotating.