JPS59231359A - Light and heat collecting device for sun light - Google Patents

Abstract

PURPOSE:To provide the title device in which the light and heat collecting efficiency is improved, the use of molten salt is facilitated and generation of thermal strain is prevented by collecting solar light of high density led out by flexible optical fibers to a common heat collector by fixed mirrors disposed within a large number of channels provided radially around a heat collctors, and converting the solar light into thermal energies. CONSTITUTION:Flexible optical fibers 3 are fitted to light collectors 1 and 2 so that one end surface of each of the optical fibers 3 is positioned at a light collecting point of solar light L, and collected solar light is led out by the optical fibers 3. A large number of channels 6 are formed below the ground surface radially centering around the heat collector 4, and are covered with a lid member 7. Perforated holes 7a are provided at suitable positions of the lid member 7. Other ends of the optical fibers are collectively inserted into the perforated holes 7a, and fixed mirrors 8 inclined at an angle of 45 deg. are disposed below the holes 7a. Thus, the light from each optical fiber 3 is reflected toward the heat collector 4. By this arrangement, sun tracking devices of respective light collectors do not reqire high accuracy and may be simple in construction.

Description

[Detailed description of the invention] This invention is a solar light concentrator for efficiently concentrating sunlight and extracting a large amount of thermal energy in a system that utilizes the sun's thermal energy such as solar thermal power generation. Regarding a heat collection device.

4. Systems that utilize the sun's thermal energy, especially solar power generation plants that require high-density thermal energy, are broadly divided into ``concentrated systems'' and ``distributed systems.''

The conventional concentration method, also known as the tower concentrating method, involves arranging a large number of hemi-ostats (plane mirrors) on a large flat site, installing a tower in the center of the group of hemi-ostats, and installing a tower at the top of the tower to collect heat. The reflected light from each heliostat is concentrated in a vessel, which converts sunlight into thermal energy, heats the medium (water or molten salt, etc.) in the heat collection tube, and guides it to the ground via a pipeline. This method supplies steam to a turbine generator via a heat storage device.

However, this tower condensing method requires a high-precision tracking device for each heliostat in order to concentrate sunlight in one place from a wide area, and the positional relationship between each heliostat and the tower is slightly different. Therefore, each tracking device must be made to move differently, making the tracking mechanism and its control device complicated and expensive, and its maintenance requires a great deal of effort and expense.

Moreover, since it is not possible to make sunlight incident approximately perpendicularly to the mirror surfaces of all heliostats, the effective utilization rate of the mirrors is not very good.

Furthermore, heavy objects such as heat collectors and steam drums must be supported at the top of the tower to withstand earthquakes and strong winds, which requires a large and sturdy tower structure, which increases construction costs. Moreover, there is also the problem that tracking becomes difficult when the tower swings due to wind or the like.

Furthermore, it is difficult to insulate heat collectors to keep them warm on cloudy days or at night, and a large amount of heat is lost while leading high-temperature steam to the ground through long pipelines, making it difficult to use solar energy. There is a problem of low efficiency.

On the other hand, in the distributed method, a large number of solar collectors are distributed over a large site, each collector converts sunlight into thermal energy, and the heat is transferred to a heat collecting medium (oil, hot water, or This method uses a pipeline to guide the light to the center using steam, etc., and a parabolic mirror, Fresnel lens, etc. is used as the condensing device.

With this method, the tracking accuracy of the sun is lower than that of the concentrated method, and since all the concentrators need to be moved in the same position, the tracking device is simple and inexpensive, and there is no need for a tower. It has the advantage of being low cost.

However, since the light collection magnification is as low as about 10 to 100 times, it is difficult to obtain a high temperature.

Therefore, a solar thermal power generation plant using a curved surface concentrating method that incorporates the characteristics of the above-mentioned concentrated method and distributed method is being constructed in Nio Town, Kagawa Prefecture.

In this method, a large number of flat reflecting mirrors are distributed and installed in multiple units, and each unit has a curved mirror with a heat collecting tube at its focal point, which is placed facing each other. The light is reflected toward a curved mirror, and the reflected light from the curved mirror is focused on a heat collection tube. There, sunlight is converted into thermal energy.

Generates high-temperature, high-pressure steam. The heat collection pipes of each unit are connected by a pipeline, and the generated steam is supplied to the turbine generator via the molten salt heat storage device.

According to this method, it is possible to obtain steam at the same high temperature and pressure as the tower condensing method, so the power generation capacity is also about the same, and since no tower is required, the construction cost is lower. Tracking of each plane mirror requires high precision, similar to the tower condensing method.

Furthermore, this method does not solve the problems of difficulty in keeping warm in the heat collector and heat loss in the pipeline.

In particular, if a molten salt such as NaNO3 or KNO3 is used as a heat collecting medium, the conversion efficiency into thermal energy will be improved;
If the temperature drops below 200℃, it will solidify, so
In each of the conventional methods described above, the heat collector (
It was difficult to keep heat collecting pipes and pipelines at 200°C or higher at all times, so they could not be used.

Furthermore, in the conventional focusing method and curved surface focusing method.

It is difficult to concentrate sunlight evenly over the entire surface of a heat collector or heat collection tube, and uneven light concentration causes large temperature differences on different parts of the surface, which can lead to damage due to thermal distortion, which reduces durability. But there was a problem.

This invention solves various problems in the conventional condensing and heat concentrating devices described above, has high condensing and heat concentrating efficiency, extremely reduces heat loss during thermal energy transport, and uses molten salt. It is an object of the present invention to provide a solar light condensing and heat concentrating device that is easy to install, can prevent the occurrence of thermal distortion, and can be constructed at relatively low cost.

Mr. Tsuji Therefore, the solar light concentrating heat collecting device according to the present invention is a movable reflector equipped with a tracking device for tracking the sun, similar to the light concentrating device in the conventional distributed type solar heat collector described above. Sunlight is concentrated by multiple concentrators made of mirrors or lenses, and then guided as light through flexible optical fibers. Fixed mirrors arranged in a number of radial channels collect the heat toward a common collector, where it is converted into thermal energy.

Nu Shi 24 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, 1 is a condenser using a parabolic mirror 11 and a plane mirror 12 placed in front of its focal point, and 2 is a condenser using a Fresnel lens 21.
5.23 and the tracking device 14. The optical axis of the parabolic mirror 11 or Fresnel lens 21 (
(indicated by a dashed-dotted line) is tracked so that it points approximately toward the sun, but the tracking accuracy does not need to be that high.

Each of the light concentrators 1 and 2 has a flexible optical fiber (B) attached so that one end face thereof is located at the condensing point of sunlight, and the collected sunlight is led out through the fiber 3.

As shown in Fig. 2, a large number of such condensers 1 and 2 (only one of them may be used) are arranged in blocks (seven in the illustrated example), and a large number of condensers 1 and 2 are arranged in the central part of the whole. A heat collector 4 is covered with a heat insulating wall 5 and installed underground or semi-underground.

A large number of channels 6 are formed radially below the earth's surface (indicated by S in FIG. 1) around this heat collector 4, and are covered with a lid 7.

A through hole 7a is provided at an appropriate position on the lid 7 of each channel 6,
The other ends of the optical fibers 3, one end of which is connected to a plurality of concentrators 1 or 2 constituting one block, are inserted into one through hole 7a, and a 45° angle A tilted and fixed mirror 8 is disposed to radiate high-density light substantially vertically from the end face of each optical fiber B, and the fixed mirror 8 reflects it substantially horizontally toward the heat collector 4.

Therefore, it is possible to collect high-density sunlight almost uniformly around the outer circumference of the heat collector 4 through each channel 6, convert it into thermal energy, and introduce the heat collecting medium (water (or molten salt) W is used to generate high-temperature, high-pressure steam (2), which is supplied to the turbine generator 10 shown in FIG. 2 through a short pipe 9b to generate electricity.

In this case, high-temperature, high-pressure steam may be supplied to the turbine generator via a heat storage device, but since the heat collector 4 itself is installed underground and covered by a heat insulating wall 5, heat retention is good. Furthermore, since a heat storage material can be placed inside the heat collector 4, it can also serve as a heat storage.

In the example shown in Figure 1, the depth of the channel 6 is set to two levels, and the sunlight collected by the two blocks of collectors passes through a part of the common channel and is directed upward and downward to the collectors. I am trying to irradiate different positions, but this is done in 3 different locations.
There may be more than one stage, or there may be only one stage, and all different positions in the circumferential direction of the heat collector may be irradiated.

In addition, each channel 6 is shown as just a groove dug from the ground surface, but the surrounding wall may be hardened with cement etc.
It may be formed by embedding a U-shaped groove block or a pipe material made of metal or synthetic resin.

As the heat collector 4, an appropriate one such as one in which many thin U-shaped pipes are arranged in a basket shape or a boiler type one can be used depending on the purpose.

Furthermore, in order to further shorten the length of the optical fiber used, the optical fiber 3 is used for the length necessary to allow rotation of the condenser 1.2 by the tracking device 14.24, and then It is also possible to provide a subduct and a submirror on the ground so that the sunlight led out by the optical fiber B is directed toward the mirror 8 in the main duct 6.

The solar light condensing and heat concentrating device according to the present invention as described above has many advantages over conventional tower concentrating type or curved surface concentrating type devices, as follows.

(1) The solar tracking device of each concentrator does not require very high precision like the conventional distributed type, so it can be simple and inexpensive.

(2) If the incident light beam to each condenser is tracked so as to be substantially parallel to the optical axis of the reflecting mirror or lens, the effective utilization rate of the mirror or lens is good.

(3) The transmission loss of optical energy through optical fibers is extremely small, but the length of the optical fibers used can be shortened.
Most of the light energy is transmitted directly to the heat collector through the spatial light path secured by the channel, and the heat collector can be installed in one place above ground or underground, so it can be easily connected to thermal energy utilization devices such as turbine generators. Piping can be made extremely short and energy loss can be significantly reduced.

(4) It is possible to obtain a light condensing magnification comparable to that of the conventional tower condensing method, and since no tower is required, construction costs can be significantly reduced.

(5) It is easy to maintain a high temperature by insulating the heat collector and adding a heat storage function, and it is also possible to equalize the amount of light input to the heat collector surface.
The heat collector will not be damaged due to thermal distortion.

(6) In addition to (5) above, since the output piping from the heat collector can be extremely short, it is easy to keep warm together with the heat collector by electric heating etc. at night, so it can be used as a heat collecting medium. The use of molten salt also eliminates the risk of solidification.

(7) If the channel is hinged on the ground surface, it will be possible to reduce the temperature change inside the channel, and it will be easier to prevent the effects of wind, mist, etc., and the transmission loss of light energy within the channel will be further reduced. Can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional configuration diagram showing one embodiment of the present invention, and FIG.
The figure is also a schematic plan configuration diagram thereof. 1.2...Concentrator 3...Flexible optical fiber 4
... Heat collector 5 ... Heat insulation wall 6 ... Channel 7 ... Lid body 8 ... Fixed mirror 9a
,'3b...Piping 10...Turbine generator

Claims (1)

[Claims] 1. A large number of concentrators made up of movable reflecting mirrors or lenses, each equipped with a tracking device that tracks the sun, and flexibility to derive the sunlight collected by each concentrator, respectively. an optical fiber, and a fixed mirror that reflects sunlight guided by the optical fiber toward a common collector;
A solar light collecting and heat collecting device comprising a large number of channels provided radially around the heat collector to ensure an optical path between each of the fixed mirrors and the heat collector. 2. The solar light condensing and heat collecting device according to claim 1, wherein each of the channels is provided below the ground surface.