JPS603488A - Distributed type solar energy power plant - Google Patents

Abstract

PURPOSE:To aim at making a solar heat collector cheap and also at reducing the installation cost of a power plant and as well the unit price of power generation, by providing such an arrangement that a low boiling point medium is directly heated in a stationary solar heat collector, and is subjected to evaporation and vapor-separation in a gas-liquid separator so that the thus obtained vapor is used for power generation. CONSTITUTION:Each stationary type solar heat collector 11 which is laid in a position related to its power plant and set in a direction most suitable throughout the year, may heat a low boiling point medium 12 passing therethrough when it receives the direct light from the sun and even when it receives the scattered light of the sun. The low boiling point medium 12 which is heated but not yet completely evaporated is collected from the heat collectors while it is maintained in its liquid phase, and flows into a gas- liquid separator 13 laid in the vicinity of a low boiling point medium turbine 14 and above the collectors 11. The vapor of the low boiling point medium 12 which has been separated from the liquid phase rotates the low boiling medium turbine 14 so that a generator 7 produces electrical power. With this arrangement, the heat collector may be cheap and also utilize the scattered light of the sun. Accordingly, the operating time of the heat collector may be made long, and the installation cost of the plant and as well the unit price of power generation may be reduced.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a distributed solar thermal power generation plant, and more particularly to a heat transfer medium system of a distributed solar thermal power generation plant using a fixed solar heat collector. .

[Technical background of the invention and its problems]

As a new form of energy, solar thermal power generation technology is being developed, but solar thermal power plants have high equipment costs and their operation is highly dependent on the weather, resulting in low operating rates. tends to be low, and at present the
The cost of tonne has become prohibitive, and it has not been put into practical use due to economic considerations. Therefore, the biggest issue for the time being is reducing plant equipment costs.

Since heat collection equipment accounts for a large proportion of plant equipment costs, making the heat collection equipment inexpensive is an important key to achieving economic efficiency.

By the way, in the development of solar thermal power generation plants to date, in order to make the system more efficient, solar power has been focused using mirrors, etc. to obtain a high temperature of 250 to 300'C (in the case of a distributed type). It was considered. However, such concentrating heat collecting devices have moving parts because they need to track the sun, and a high-precision solar tracking device is essential, making them expensive. Furthermore, (2) the condensing type heat collecting device is
The drawback is that only direct sunlight can be used.

However, there are surprisingly few clear days in Japan, and even when the sun is shining, there are never many hours of continuous direct sunlight.

Figure 1 shows one example of a distributed solar power generation plant using conventional technology.
It is a system diagram showing the concept of the method. Within the premises of the plant (Secondly, a large number of condensing type heat collecting devices 1 are installed. Concentrating type heat collecting devices 1 include those that condense light with a concave mirror and those that condense light with a lens. The generated solar energy is transmitted to the heat medium 2 through its focal line or focal point, and the heat medium 2 is heated to a high temperature. The heat is transferred, the temperature of the water decreases, and the heat medium pump 5 sends it back to the condensing heat collector 1 (2), where it is circulated and used. On the other hand, water 4 heated by the evaporator 3 becomes steam. , rotates the steam turbine 6, and generates electricity from a generator 7 (secondary) connected to the steam turbine 6.

The turbine exhaust gas, whose temperature and pressure have been reduced by providing energy to the steam turbine 6, is cooled by cooling water 9 in a condenser 8, condensed into condensed water, and sent to the evaporator 3 again by a water pump 10.

FIG. 2 is a system diagram showing the concept of another type of distributed solar thermal power generation plant according to the prior art. This method also has a large number of concentrating heat collectors 1, similar to the method shown in FIG. 1, but in this method, water 4 is directly heated by solar heat. Then, the water 4 is evaporated in the evaporating section 1a, becomes superheated steam in the superheating section 1b, enters the steam turbine 6, and rotates it.

Comparing both the systems shown in Figures 1 and 2, we find that in the system shown in Figure 1, the heat medium 2 is liquid at all locations in the system, so the pressure inside the piping is low and the diameter of the piping is small. good.

However, not only is the evaporator 3 required to evaporate the water 14 using the heat of the heat medium 2, but the temperature of the steam obtained in the evaporator 3 must be lower than the temperature of the heat medium 2, which is the heating side. I don't get it.

On the other hand, in the method shown in FIG. 2, since the water 4 is directly heated by solar heat, the evaporator 3 is not necessary, and the temperature obtained by the solar heat becomes the inlet steam temperature of the steam turbine 6. However, in this method, if we consider that the steam turbine 6 is driven by saturated steam, the concentrating heat collecting device l is composed of only the evaporator part 1a, but in order to improve the steam condition (two superheated steam When applied, the downstream side of the evaporating section 1a (=superheating section 1b
need to be installed. Since the superheating section 1b serves as a heat collecting device that heats gas (steam), it has poor heat transfer performance compared to the evaporation section 1ai, which is a factor that impairs economic efficiency. Furthermore, since the piping from the superheating section 1b to the steam turbine 6 is a piping that passes gas rather than liquid, its diameter is large, resulting in high equipment costs (second reason).

As mentioned above, both types have their own disadvantages, and since they use a concentrating heat collector 1 that can only use direct light, they require a solar tracking device as mentioned above (2 types) It also has the disadvantage of being short in time.

[Purpose of the invention]

The present invention addresses the above-mentioned problems by using an inexpensive heat collection device that can utilize not only direct light but also scattered light and has no moving parts, thereby allowing the reduction in system efficiency to be compensated for. The purpose of this project is to provide a low-cost, high-operating-rate distributed solar thermal power generation plant that more than compensates for this.

[Embodiments of the invention]

Figure 3 shows one of the distributed solar power generation plants according to the present invention (-).
It is a system diagram starting an example. The first feature of the present invention is that a fixed heat collecting device 11 is used as the heat collecting device.

The fixed heat collecting device 11 may be of a flat plate type, an inverted flat plate type, a vacuum tube type, a vacuum tube type with a reflector, etc., but any type may be used.

It is preferable to use one that can obtain as high a temperature as possible, but it would be meaningless if it becomes a factor that hinders economic efficiency, so the most appropriate one should be selected by considering the economic efficiency of the entire system. Further, it is also possible to divide the temperature range into one type (it is not necessary to limit it to one type, and to divide the temperature range into a low temperature part and a high temperature part or more) and apply the most suitable one to each.

The second feature of the present invention is that a low boiling point medium 12 is used as a material to extract heat through a fixed heat collecting device 11, and the low boiling point medium turbine 14 is rotated by the steam. This is because in the case of the present invention, the temperature obtained is 100 to 150°C because the fixed heat collector 11 is used, and if water is used, the steam will not have enough pressure to rotate the steam turbine. It is from.

The third feature of the present invention is that the evaporation of the low-boiling point medium 12 is not completed in the fixed heat collecting device 11, but is evaporated to the vicinity of the low-boiling point medium turbine 14 in a heated liquid state. A gas-liquid separator 13 installed near the fixed heat collector 1 and higher than the 1st fixed heat collector
The purpose is to perform gas-liquid separation and obtain vapor of the low boiling point medium 12.

In a distributed type solar thermal power generation plant, the heat collector is distributed within the plant site (-), so the piping from the heat collector to the turbine must be long. When using such a condensing type heat collecting device 1,
Because the heat collectors are connected relatively in series to obtain high temperatures, only a small portion of the total heat collectors undergoes the final stage of heating. Therefore, if each heat collector is arranged so that it approaches the turbine according to the heating process, the piping from the final heat collector group to the turbine does not need to be so long. - In the method of Rikiki's invention, fixed heat collecting devices 11 are used and the heating temperature is low, so each heat collecting device is used in a state close to parallel. This means that there are an extremely large number of heat collectors that handle the final stage of heating, and the piping that connects these heat collectors and the turbine must necessarily become long. Therefore, if this piping is used as a steam piping, the diameter will be large, and the cost of the piping itself and the heat insulating material covering it will be high, impeding economic efficiency. The present invention allows this piping to be a small-diameter piping for liquid.

Furthermore, in the present invention, since the low boiling point medium 12 is directly heated within the fixed heat collecting device 11, the evaporator 3 required in the prior art shown in FIG. 1 is not required. As mentioned above (2. In the evaporator 3, there is a considerable temperature difference between the heated fluids, so in the case of the present invention, which configures the thermal cycle at a lower temperature than the condensing type, the steam temperature at the turbine inlet must be The present invention, which does not use the evaporator 3, is advantageous in order to bring the temperature as close as possible to that obtained by the heat collector.

Furthermore, in the present invention, since the evaporation of the low-boiling point medium 13 is not completed within the fixed heat collector 11, all solar heat is used to heat the liquid, which has better heat transfer performance than gas heating. The device is also economical.

In particular, in the present invention, since the low boiling point medium 12 is used as the operating medium, its characteristic is that in order to rotate the low boiling point medium turbine 14 (generally (two saturated steam is sufficient, there is almost no need to use superheated steam. There is no need to evaporate the low boiling point medium 12 into a gas within the fixed heat collecting device 11, and it would be inconvenient if it evaporated into superheated steam.

Furthermore, in the present invention, since the gas-liquid separator 13 is installed, the liquid level here is monitored by the level detectors T and C1, and the flow rate adjustment valve 17 at the outlet of the low-boiling point medium pump 16 is controlled. By doing so, it becomes extremely easy to control the flow IYI of the low boiling point medium 12 supplied to the fixed heat collecting device 11.

Next, the present invention will be explained in detail.

The fixed heat collector 11 is installed at the construction point of the plant in the most appropriate direction throughout the year,
Not only does it receive direct light from the sun, but even if the sunlight is blocked by clouds, it receives scattered light from the sky.
The low boiling point medium 12 flowing inside is heated. The heated low-boiling point medium 12 is not completely evaporated and is collected from each heat collecting device while maintaining a liquid state, and is sent to the low-boiling point medium turbine 14.
The heat flows into the gas-liquid separator J3, which is a fixed type and is installed at a higher location than the heat collecting device 11. The gas-liquid separator 13 corresponds to the drum of a drum boiler, and the level is controlled so that the liquid level is at an appropriate position inside the drum. The gas phase part here is connected to a low boiling point medium turbine 14 nearby (= a certain low boiling point medium turbine 14, and the vapor of the low boiling point medium 12 is separated from the liquid phase and guided to the low Wi point medium The medium turbine 14 is rotated, and the power generator 7 connected thereto generates electricity.The exhaust gas of the low boiling point medium turbine 14 enters the condenser 15, is diluted by the cooling water 9, and returns to a liquid after forming the core 7. , is sent to the fixed heat collecting device 11 again by the low boiling point medium pump 16.This flow rate is calculated as follows:
Based on the level of 3, flow%, ffl;'6 Valve adjustment 17
controlled by In addition, before starting the plant, the temperature of the low boiling point medium 12 in the gas-liquid separator 13 is low, so
At startup, this is sent to the identification type heat collector 11 by the low boiling point medium circulation pump 18.1. q17 is heated to a temperature at which steam can be obtained at which the low boiling point medium turbine 14 can be operated. A check valve 19 is provided at the outlet of the low boiling point medium circulation pump 18 in order to prevent the cold low boiling point medium 12 from the low boiling point medium pump 16 from directly flowing into the gas-liquid separation Ml device 13 when the pump is stopped. It is.

The low boiling point medium circulation pump 18 should not be operated only when starting up the plant, but can also be operated for temperature control of the gas-liquid separator 13, etc. even during plant operation.

There is no problem even if a portion of the low boiling point medium 12 begins to evaporate inside the fixed heat collector 11 . However, if evaporation progresses too much, the flow in the piping from the fixed heat collector 11 to the gas-liquid separator 13 will become a typical two-phase flow, which may increase piping resistance or increase the flow rate of each heat collector. In some cases, problems such as extremely unbalanced (two) may occur.In addition, the piping of the low boiling point medium 12 is connected to the gas-liquid component: lf! It is also possible to install a pressure reducing valve (not shown) to prevent evaporation by increasing the pressure just before the vapor enters the gas-liquid separator 13, and then to reduce the pressure and generate flash steam when the vapor enters the gas-liquid separator 13. Conceivable.

Flow rate control of the low-boiling point medium 12 (two examples are shown in Fig. 3). It goes without saying that other methods, such as controlling by changing the discharge amount of the low boiling point medium pump 16, are also applicable.

〔Effect of the invention〕

As described above, the present invention uses a fixed solar heat collector that does not require solar tracking to directly heat a low-boiling point medium, and then evaporate and separate the low-boiling point medium using a gas-liquid separator to drive a turbine. Because it generates electricity by rotating the heat collector, the heat collector is inexpensive, and scattered light can also be used, so the plant can operate for a long time.The piping between the heat collector and the turbine can be small in diameter, and control is easy. This will make it possible to realize the Hatsu-Tun plant.
This has a significant effect on reducing equipment costs and power generation unit costs for distributed solar power generation plants.

[Brief explanation of the drawing]

Figure 1 shows one example of a distributed solar power generation plant using conventional technology.
Figure 2 is a system diagram showing the concept of the method;
FIG. 3 is a system diagram showing one embodiment of a distributed solar power generation plant according to the present invention. 7...Power generation 1 9...Cooling water 11...Fixed heat collector 12...Low boiling point medium 13
... Gas-liquid separator 14 ... Low boiling point medium turbine 15
...Different condenser 16-...Low boiling point medium pump 17...
Flow rate adjustment valve 18...Low boiling point medium circulation pump

Claims (3)

[Claims] (1) A fixed type solar heat collector (a distributed solar thermal power generation plant characterized by generating electricity by heating through two low-boiling point media and rotating a low-boiling point medium durbin with the steam of the low-boiling point medium). (2) The low boiling point medium has completed evaporation in the fixed solar heat collector, and in a heated liquid state, the low boiling point medium is placed in the vicinity of the low boiling point medium turbine and exposed to the fixed solar heat collector. A patent claim characterized in that the low-boiling point medium vapor generated and separated in the gas-liquid separator is led to a gas-liquid separator located at the duct and flows into the low-d;↓ point medium turbine. The distributed solar thermal power generation plant according to item 1. (3) The first scope of Patent i1, characterized in that the flow rate of the low boiling point medium supplied to the fixed solar heat collector is controlled according to the liquid level of the air distribution liquid separator. 2. Distributed solar thermal power generation plant according to paragraphs 1 and 2.