JPS647227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a geothermal power generation system that effectively utilizes geothermal energy.

Conventional technology In order to contribute to Japan's long-term energy supply,
As part of the development of various energy sources, research and development of geothermal power generation using geothermal energy is being conducted.

By the way, the various geothermal power generation systems that have been developed so far target geothermal steam wells with self-injection capability, and generate turbines using only the steam out of the steam and hot water mixed fluid that self-injects from the production well. Geothermal steam power generation systems that drive generators to generate electricity were the mainstream.

In this case, the hot water separated from the air-water mixture was returned underground through a reinjection well without being used. Therefore, the utilization efficiency of the total energy of the ejected steam-water mixed fluid decreases by the amount of energy possessed by the hot water.

Therefore, in order to utilize the energy of this geothermal hot water for power generation and increase the effectiveness of the geothermal power generation system as a whole, a power generation plant using geothermal hot water using a binary cycle is being developed.

This binary cycle power plant utilizes the energy of hot water separated from a steam/water mixture that self-injects from a dedicated production well or a production well for a geothermal steam power plant to use a low boiling point medium (e.g. Freon, isobutane, etc.) are vaporized in a closed cycle, and the vaporized high-pressure medium steam drives a turbine generator to generate electricity.

Binary cycle power generation plants, which are power generation systems that utilize geothermal hot water, have already been developed.
It has been demonstrated by a 1000KW class pilot plant.

However, in order to put this into practical use, it is necessary to install at least a 10 MW class binary cycle power generation plant alongside the steam power plant, and in order to do so, for example, 1400 t/H of 130°C class hot water, which has been discarded until now, must be installed. It becomes necessary. However, this amount cannot be guaranteed even in existing 50MW class steam power plants.

This is because, of course, in areas where there is little hot water in the ejected air-water mixed fluid, but even in areas where there is a lot of hot water, it is necessary to use hot water to return it to the local community as an effective use of waste hot water. This is because multi-purpose use is planned.

Therefore, a binary cycle power generation plant attached to a 50MW class geothermal steam power generation plant is
If geothermal energy becomes small (less than 10 MW), its economic efficiency and position as an alternative energy source will decline, and geothermal developers and electric power companies will have less interest in developing geothermal energy.

Purpose This invention solves the above-mentioned problems and makes it possible to utilize geothermal energy by making it possible to install a binary cycle power generation plant with a sufficiently large output by simply supplying a portion of the required amount of hot water from a geothermal steam power generation plant. The aim is to provide a highly efficient geothermal power generation system.

In addition, although some wells were drilled for steam production in the area of existing geothermal power plants, there are wells that do not have the ability to produce water at the time of drilling, and wells that produce water but have a small amount of water (these are referred to as "failed wells" in this specification). ), and there are always several wells that were used as production wells but whose ejection volume has significantly decreased (referred to as "attenuated wells" in this specification). As a result of the survey, the bottom hole hot water temperature of these wells is in the range of approximately 200 to 240℃ (average 220℃).
Since the water level in the well was found to be approximately 200 meters underground, the aim is to utilize this as a hot water supply source for a binary cycle power generation plant.

Configuration Therefore, the geothermal power generation system according to this invention has the following features:
A geothermal steam power generation plant that generates electricity by driving a turbine generator with steam separated by a steam and water separator from a steam and water mixed fluid ejected from a geothermal steam well;
A part of the hot water separated by the steam-water separator is supplied to the failed well or attenuation well, and the hot water is pumped to the ground by an in-well pump installed in the failed well or attenuation well. This system consists of a binary cycle power generation plant that uses the energy of pumped hot water to vaporize a low-boiling point medium and uses the vaporized high-pressure medium steam to drive a turbine generator to generate electricity.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic piping diagram showing a basic embodiment of the geothermal power generation system according to the present invention, in which a geothermal steam power generation plant 1 and a binary cycle power generation plant 2 are combined, but the configuration of each of these plants itself is This is similar to what has already been developed.

However, the steam and water mixture ejected from the geothermal steam well 3 is separated by the steam separator 4, and the reinjection well 5
A part of the hot water that is returned to the underground through the pipe is supplied to the failed well or attenuation well 6 through the pipe 7, and as shown enlarged in Fig. The system is characterized in that a well pump 8 is used to pump a hot water mixture of hot water injected from the outside and hot water in the well above ground, and a means is provided for supplying the mixed hot water to the binary cycle power generation plant 2 through a pipe 9.

In addition, 10 is binary cycle power generation plant 2
Reduction well for returning hot water to underground, 11
is a silencer for alleviating the noise emitted from the geothermal steam well 3.

The geothermal steam power generation plant 1 is supplied with steam separated by a steam/water separator 4 and drives a steam turbine 12a of a turbine generator 12 to generate the generator 12.
b is rotated to generate electricity, and the generated electricity is output via the transformer 13.

The steam discharged from the steam turbine 12a enters the condenser 14, where it is condensed and stored in the hot water tank 15. The steam is pumped up by the hot water pump 16 and supplied to the cooling tower 17, and then pumped from the reservoir 18 by the water intake pump. 19 and supplied to the cooling water tank 17a of the cooling tower 17, the cooling water pump 2
0 again to the condenser 14.

The steam that has not been condensed in the condenser 14 is sent to the cooling tower 17 by the vacuum pump 21, where part of it is evaporated and the rest is condensed.

On the other hand, in the binary cycle power generation plant 2, hot water is pumped up from a failed well or attenuation well 6 by an in-well pump 8 and supplied through a pipe 9, and then passed through an evaporator 22 and a preheater 23, and then passed through a reinjection well. 1
Eject to 0.

In the evaporator 22, the water is stored in a hotwell tank 24, and is transferred to a preheater 23 by a feed pump 25.
A low boiling point medium (eg, Freon 114), which is a secondary working fluid, circulated through is vaporized by heat exchange with the thermal energy of the hot water.

The resulting high-pressure medium steam drives the medium turbine 26a of the turbine generator 26, rotates the generator 26b, and generates electricity, which is output via the transformer 27.

The medium vapor discharged from the medium turbine 26 a is condensed and liquefied through the condenser 28 and returned to the hot well tank 24 . 29 is a spray water pump.

The circulation path for this low boiling point medium is a closed cycle, and there is no need to replenish the medium.

Here, as shown in Fig. 2, for example, 333 tons of hot water at 130°C is poured into the failed well or attenuation well 6 through the pipe 7.
H is supplied to 220℃ from the bottom of failed well and attenuation well 6.
Assuming that 267t/h of hot water can be pumped,
It is pumped up by the well pump 8 and sent to the pipe 9.
The hot water supplied to the binary cycle power generation plant 2 through the hot water is 600t/H at 170°C.

This can provide thermal energy equivalent to the thermal energy provided by 1400 t/h of hot water at 130°C, making it possible to obtain a power output of 10 MW class.

Therefore, from the geothermal steam power plant 1 side,
Since the amount of hot water supplied at 130°C can be kept to the 300t/H range, it can be used in 50MW class steam power plants when there is little hot water in the steam/water mixture, or when the hot water is used for multiple purposes. It will be possible to provide sufficient supply even in the case of

In the embodiment shown in Fig. 1, a part of the hot water discharged from the steam water separator 4 is supplied to the failed well and the attenuation well 6, and the rest is all returned underground. Of course, if there are many, this can also be used for other purposes.

Effects As is clear from the above explanation, the geothermal power generation system according to the present invention allows a geothermal steam power generation plant to be attached to a sufficiently economical high-output binary cycle power generation plant, and utilizes unused heat from failed or attenuated wells. By utilizing water, the necessary supply amount of hot water can be easily secured, making it possible to construct a geothermal power plant that has high efficiency in using geothermal energy as a whole.

Furthermore, the present invention has many advantages as follows.

(1) The heat resistance of an in-hole pump installed in a failed or damped well is originally controlled by the bottom hole temperature itself (200 to 240℃). By injecting water, the average temperature in the well is lowered, which lowers the pump's maximum temperature tolerance and extends the pump's service life.

(2) When hot water is pumped up from a well using an in-well pump, the water level in the well generally decreases from the initial water level L ₀ shown in Figure 2 as soon as pumping starts, which is controlled by the characteristics of the well. However, by injecting waste hot water from the steam power plant side, this water level can be prevented from dropping, so it can be used even in wells with small capacity. be able to.

(3) Compared to the case where exhaust hot water from the steam power plant side is directly supplied to the binary cycle power plant, the temperature of the hot water can be increased (for example,
130℃ → 170℃), and the supply amount per unit time can be reduced (for example, 1400t/H → 600t/H),
The heat transfer area of heat exchangers such as preheaters and generators in binary cycle power generation plants can be reduced.

(4) A mixing tank is required when hot water is pumped up from a failed or attenuated well and then mixed with waste hot water from the steam power plant and supplied to the binary cycle power plant. According to this method, such a mixing tank is not required.

[Brief explanation of the drawing]

FIG. 1 is a schematic piping diagram showing a basic embodiment of the geothermal power generation system according to the present invention, and FIG. 2 is an enlarged view of the in-well pump installation section. 1...Geothermal steam power plant, 2...Binary cycle power plant, 3...Geothermal steam well, 4...Steam water separator, 5...Reduction well, 6...Failed well or attenuation well, 8...In-well pump, 10...Reduction well , 12, 26...Turbine generator.

Claims (1)

[Claims] 1. A steam separator that separates the steam and water mixture ejected from a geothermal steam well into steam and hot water, and a geothermal system that generates electricity by driving a turbine generator with the steam separated by the steam separator. A portion of the hot water separated by the steam power plant and the steam water separator is supplied to the failed well or attenuated well, and the hot water is pumped above ground using an in-well pump installed in the failed well or attenuated well. A low boiling point medium is vaporized in a closed cycle by the energy of the hot water pumped up by the hot water pumping means, and a turbine generator is driven by the vaporized high pressure medium steam. A geothermal power generation system consisting of a binary cycle power generation plant that generates electricity.