JP6381264B2 - Binary power generation apparatus and binary power generation method - Google Patents

Description

  The present disclosure relates to a binary power generation apparatus and a binary power generation method.

Binary power generation is a power generation method in which a low-boiling point medium is heated and evaporated by a heating source, and the expander is rotated by the steam to drive the generator. One feature is that a fluid of 100 ° C. or lower can be used as a heating source, and low-temperature exhaust heat (drainage or exhaust gas) from a factory, hot water generated by geothermal heat, or the like can be used effectively.
Patent Document 1 includes two heat exchangers that evaporate and superheat the working medium by the heat of the heat source, and an expander that expands the steam of the working medium superheated by the heat exchanger and generates a rotational driving force. A binary power generator that drives a generator using this rotational driving force is described. Further, in this binary power generation apparatus, it is described that a factory exhaust heat or hot water from a hot spring is used as a heat source, and a low-boiling organic medium such as pentane, hexane, or alternative chlorofluorocarbon (R245fa) is used as a working medium. Has been.

JP 2013-185788 A

By the way, in a heat exchanger used in a binary power generator, heat exchange between a heat source fluid and a low-boiling working fluid is performed. At this time, if a fluid in which a crystallizable substance is dissolved is used as a heat source, a crystallized product may be generated in the channel due to pressure loss in the fluid channel. In this case, since the flow path may be clogged with crystallized substances, frequent maintenance is required. In addition, since a refrigerant is used as the working medium of the binary power generation apparatus, it is difficult to disassemble the heat exchanger during maintenance, and maintenance itself may be difficult.
If the precipitation of crystallized substances in the flow path in the heat exchanger can be suppressed when the crystallizable substance is dissolved as the heat source of the binary power generation device, the frequency and work load of the heat exchanger can be reduced, and the binary The operating rate of the power generator can be improved.

  An object of at least one embodiment of the present invention is to provide a binary power generation apparatus and a binary power generation method capable of suppressing generation of crystallized substances in a heat exchanger for performing heat exchange between a heat source and a working fluid.

A binary power generator according to at least one embodiment of the present invention,
A generator,
An expander having a rotating shaft connected to the generator;
A heat exchanger for evaporating the working fluid;
A circulation line configured to circulate the working fluid through the heat exchanger and the expander, and
A binary power generator configured to drive the generator by rotating the rotating shaft by expanding the working fluid evaporated in the heat exchanger with the expander;
Depressurizing hot water in which the crystallizable substance is dissolved to precipitate the crystallizable substance and separating the hot water into steam having a temperature lower than that of the hot water and hot water having a temperature lower than that of the hot water. A flash tank,
A supply line for supplying the hot water to the flash tank;
A first flow rate adjustment valve provided in the supply line for adjusting the flow rate of the hot water supplied to the flash tank;
The heat exchanger is configured to evaporate the working fluid by heat exchange with the steam.

When hot water in which a crystallizable substance is dissolved is used as a heat source for heat exchange with the working fluid in order to evaporate the working fluid in the heat exchanger, if this hot water is introduced into the heat exchanger as it is, the flow of the heat exchanger Crystallized matter may precipitate due to pressure loss generated in the road.
On the other hand, according to the binary power generator, the hot water in which the crystallizable substance is dissolved is flushed by adjusting the flow rate of the hot water supplied to the flash tank by controlling the opening of the first flow rate regulating valve. While reducing the pressure in the tank to precipitate the crystallizable substance, the hot water can be separated into lower temperature steam and hot water, and the separated steam can be introduced into the heat exchanger. For this reason, since the content of the crystallizable substance contained in the steam introduced into the heat exchanger is significantly reduced as compared with the hot water before separation, the generation of crystallized substances in the heat exchanger is suppressed. .

In some embodiments, the binary power generator includes a discharge line for discharging the hot water from the flash tank;
A second flow rate adjustment valve provided in the discharge line for adjusting the flow rate of the hot water discharged from the flash tank;
In this case, the pressure in the flash tank can be adjusted more flexibly by adjusting the flow rate of the hot water discharged from the flash tank by controlling the opening of the second flow rate adjusting valve.

In some embodiments, the crystallizable material is calcium carbonate.
That is, as hot water in which a crystallizable substance as a heat source that exchanges heat with the working fluid in order to evaporate the working fluid in the heat exchanger, hot water containing calcium carbonate that is a crystallizable substance (for example, hot spring water) Etc.) can be used.

In some embodiments, the binary power generator includes a hot spring well,
A part of the hot spring water erupted from the hot spring well is grounded in the hot spring well so that the upward rising speed of the hot spring water in the hot spring well is 1.5 m / s or more on the ground surface. It further comprises a pumping means for pumping to a deeper part,
The hot water is hot spring water obtained from the hot spring well.

In the hot spring wells of hot springs where crystallized substances have dissolved, the pressure decreases as the hot spring water rises from the deep spring springs and approaches the surface of the earth. A so-called scale) is deposited. If this state is left as it is, the precipitation of crystallized material proceeds in the hot spring well, and when the crystallized materials are combined, it becomes a cause of clogging the hot spring well. For this reason, the maintenance which removes a crystallized substance regularly is needed, and a maintenance expense and a work burden generate | occur | produce.
According to the binary power generation apparatus provided with the above-mentioned pumping means, the hot spring water springed out from the hot spring well so that the rising speed of the hot spring water in the hot spring water in the vertical upward direction is 1.5 m / s or more on the ground surface. Since a pumping means for pumping a part to a portion deeper than the ground surface in the hot spring well is provided, retention and bonding of crystallized substances in the hot spring well are reduced. For this reason, hot spring wells are less likely to be clogged, and the maintenance frequency and work load can be reduced.

A binary power generation method according to at least one embodiment of the present invention includes:
A binary power generation method in which a generator is driven by a working fluid,
Depressurizing step of depressurizing hot water in which the crystallizable substance is dissolved to precipitate the crystallizable substance and separating the hot water into steam having a temperature lower than that of the hot water and hot water having a temperature lower than that of the hot water. When,
A heat exchange step of evaporating the working fluid by heat exchange with the steam;
A power generation step of driving the generator by expanding the evaporated working fluid with an expander and rotating a rotating shaft of the expander.

In order to evaporate the working fluid using a heat exchange means (for example, a heat exchanger), when using hot water in which a crystallizable substance is dissolved as a heat source for exchanging heat with the working fluid, this hot water is directly introduced into the heat exchange means. Then, a crystallized substance may precipitate due to a pressure loss generated in the heat exchange means.
On the other hand, according to the binary power generation method, the hot water in which the crystallizable substance is dissolved is decompressed to precipitate the crystallizable substance, and the hot water is separated into lower temperature steam and hot water, This separated steam can be introduced into the heat exchange means. For this reason, since the content of the crystallizable substance contained in the steam introduced into the heat exchange means is significantly reduced compared to the hot water before separation, the generation of crystallized substances in the heat exchange means is suppressed. .

In some embodiments, the hot water is hot spring water obtained from a hot spring well,
Before the decompression step, a part of the hot spring water that has springed out from the hot spring well, so that the rising speed in the vertical upward direction of the hot spring water in the hot spring well is 1.5 m / s or more on the ground surface, It further includes a pumping step of pumping to a portion deeper than the ground surface in the hot spring well.
According to the binary power generation method described above, a part of the hot spring water that is springed out from the hot spring well is adjusted so that the upward rising speed of the hot spring water in the hot spring well is 1.5 m / s or more on the ground surface. Since the pumping process of pumping to a deeper part than the ground surface in the hot spring well is provided, the hot spring well is less likely to be clogged, and the maintenance frequency and work load can be reduced.

  According to at least one embodiment of the present invention, it is possible to suppress generation of a crystallized product in a heat exchanger for performing heat exchange between a heat source and a working fluid.

It is a figure showing the binary power generator concerning one embodiment. It is a figure which shows the structure of the hot spring well periphery of the binary electric power generating apparatus which concerns on one Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples.

FIG. 1 is a diagram illustrating a binary power generator according to an embodiment.
As shown in the figure, the binary power generator 1 includes a generator 2, an expander 4 having a rotating shaft connected to the generator 2, a heat exchanger 6 for evaporating the working fluid, and a working fluid. And a circulation line 8 configured to circulate.
The circulation line 8 is configured to circulate the working fluid through the heat exchanger 6 and the expander 4.
The working fluid that circulates in the circulation line 8 evaporates by exchanging heat with steam after depressurization of hot water described later in the heat exchanger 6. The evaporated working fluid expands while passing through the expander 4, thereby rotating the rotating shaft of the expander 4. The generator 2 connected to the rotation shaft of the expander 4 is driven by the rotation of the rotation shaft of the expander 4. In this way, power is generated by the binary power generator 1.
Note that the working fluid expanded through the expander 4 is condensed in the circulation line 8 to become a liquid, and is introduced into the heat exchanger 6 again. As shown in FIG. 1, the circulation line 8 may be provided with a condenser 10 for condensing the expanded working fluid. Further, the circulation line 8 may be provided with a pump 12 for pumping the working fluid toward the heat exchanger 6.

The binary power generator 1 includes a flash tank 20, a supply line 22 for supplying hot water in which a crystallizable substance is dissolved in the flash tank 20, and a first flow rate adjustment provided in the supply line 22 outside the circulation line 8. A valve 24 is further provided.
When hot water (for example, about 100 ° C.) containing hot water in which the crystallizable substance is supplied from the supply line 22 to the flash tank 20 is decompressed in the flash tank 20, the crystallizable substance is precipitated, Steam and hot water having a temperature lower than that of the hot water (for example, about 80 ° C.) are generated. The generated hot water moves downward in the flash tank 20 due to gravity, and the steam moves upward due to its low specific gravity. In this way, steam and hot water are separated. And the vapor | steam isolate | separated in this way is sent to the heat exchanger 6, and a working fluid is evaporated by exchanging heat with a working fluid. That is, the heat exchanger 6 is configured to evaporate the working fluid by heat exchange with the steam separated as described above.
In one embodiment, the first flow rate adjustment valve 24 is opened so that the pressure in the flash tank 20 becomes a pressure suitable for the precipitation of the crystallizable substance and the generation of steam and hot water having a temperature lower than that of hot water. Adjust the degree. Thereby, the flow rate of the hot water supplied from the supply line 22 to the flash tank 20 can be adjusted, and the pressure in the flash tank 20 can be set to an appropriate value.

In the conventional binary power generation apparatus that does not use the flash tank 20, it is necessary to use a pump to guide the hot water to the heat exchanger 6. In this case, a large amount of pump power is required to guide the hot water to the heat exchanger 6 (evaporator). For this reason, the amount of power generated by the binary power generator has been reduced.
However, since the steam is condensed in the heat exchanger 6 and the pressure in the heat exchanger 6 is reduced by using the flash tank 20 as described above, the steam is guided to the heat exchanger 6. A pump for guiding the hot water to 6 becomes unnecessary, and the power is reduced accordingly. For this reason, the electric power generation amount of the binary electric power generating apparatus 1 can be improved compared with the past.

The condenser 10 may be configured to condense the working fluid by heat exchange with a fluid such as water (spring water in the example shown in FIG. 1). Further, a pump may be used to guide a fluid such as water for heat exchange with the working fluid to the condenser 10.
Further, as the condenser 10, an evaporative condenser (so-called evaporator) may be used. In this case, since the condensation temperature of the working fluid can be lowered, and when the pump is used, the power of the pump can be reduced, so that the power generation amount of the binary power generator 1 is improved. be able to.

In a binary power generator, when hot water in which a crystallizable substance is dissolved is used as a heat source for exchanging heat with the working fluid in order to evaporate the working fluid in a heat exchanger, the hot water is depressurized and crystallized as described above. When the product is introduced into the heat exchanger as it is without precipitating, the crystallized product may be precipitated due to the pressure loss generated in the flow path of the heat exchanger. For example, the case where the crystallizable substance is calcium carbonate (CaCO ₃ ) will be described more specifically. The pressure loss in the heat exchanger reduces the CO ₂ gas that can be dissolved in the hot water, thereby reducing the CO ₂ gas. The liberation proceeds (2HCO ₃ ⁻ → CO ₃ ²⁻ + CO ₂ ↑ + H ₂ O). As a result, the amount of _CO ^{3 2-} ions present in the hot water is increased, which CaCO ₃ is precipitated in combination with ^{Ca 2+} ions of hot water ^{_{(Ca 2+ + CO 3 2- →}} CaCO 3 ↓).
On the other hand, according to the binary power generation device 1 according to the above-described embodiment, the degree of crystallization is controlled by adjusting the flow rate of hot water supplied to the flash tank 20 by controlling the opening of the first flow rate adjustment valve 24. The hot water in which the substance is dissolved is decompressed in the flash tank 20 to precipitate the crystallizable substance, and the hot water is separated into lower temperature steam and hot water, and the separated steam is supplied to the heat exchanger 6. Can be introduced. For this reason, since the content of the crystallizable substance contained in the steam introduced into the heat exchanger 6 is significantly reduced as compared with the hot water before separation, the generation of crystallized substances in the heat exchanger is suppressed. The

The hot water in which the crystallizable substance is dissolved in the embodiment is not particularly limited, and for example, hot spring water generated by geothermal heat or low-temperature exhaust heat (drainage or exhaust gas) from a factory can be used. Further, the crystallizing substance is not particularly limited, and examples thereof include calcium carbonate (CaCO ₃ ). In the binary power generator 1 shown in FIG. 1, hot spring water pumped from a source is used as hot water in which a crystallizable substance is dissolved.

  The working fluid circulating in the circulation line 8 is not particularly limited as long as it can be evaporated by heat exchange with hot water in which the crystallizable substance is dissolved in the heat exchanger 6. Among them, it is preferable to use a substance having a relatively low boiling point (for example, about 80 ° C. or less). Examples thereof include halogenated hydrocarbon refrigerants such as R-245fa, and organic media such as pentane and hexane.

In some embodiments, as illustrated in FIG. 1, the binary power generator 1 further includes a discharge line 26 for discharging the warm water from the flash tank 20 and a second flow rate adjustment valve 28 provided in the discharge line 26. Prepare.
In this case, the opening degree of the first flow rate adjustment valve 24 is set so that the pressure in the flash tank 20 becomes a pressure suitable for the precipitation of the crystallizable substance and the generation of steam and hot water having a temperature lower than that of hot water. At the same time, the opening degree of the second flow rate adjustment valve 28 can be adjusted. Thereby, the pressure in the flash tank 20 can be adjusted more flexibly by adjusting the flow rate of hot water supplied from the supply line 22 to the flash tank 20 and the flow rate of hot water discharged from the flash tank 20.

A part of the vapor obtained by evaporating the working fluid by heat exchange in the heat exchanger 6 is deprived of heat by heat exchange and condensed to become hot water.
In some embodiments, as shown in FIG. 1, a condenser 32 may be provided for condensing steam obtained by evaporating the working fluid by heat exchange in the heat exchanger 6. In the condenser 32, the steam may be condensed by exchanging heat with the working fluid circulating in the circulation line 8.

Further, in some embodiments, as shown in FIG. 1, the steam that has passed through the heat exchanger 6 and the warm water generated by condensation are separated into warm water and a gas component that includes steam that remains without being condensed. A separator 34 may be provided. Examples of the gas component containing the steam that remains without being condensed include CO ₂ gas liberated from hot water, hydrogen sulfide (H ₂ S) gas contained in hot spring water, and the like. These gas components may be removed outside the binary power generator 1 by a vacuum pump 35 connected to the separator 34.

  As shown in FIG. 1, the hot water separated in the flash tank 20 and discharged from the discharge line 26 and the hot water generated by condensation of the steam that has passed through the heat exchanger 6 pass through the first hot water tank 36. Alternatively, the hot water may be stored in the second hot water storage tank 38 without passing through. Moreover, when pouring into the 2nd hot water storage tank 38, it is good also as temperature suitable for bathing by adjusting temperature with water. In some embodiments, as shown in FIG. 1, after the spring water is used for heat exchange with the working fluid in the condenser 10, the temperature of the hot water is adjusted by mixing with hot water poured into hot water storage or the like. May be. The hot water collected in the second hot water tank 38 in this way can be used for bathing, and can be delivered to bathing facilities and homes using piping and pumps.

FIG. 2 is a diagram illustrating a configuration around the hot spring well (upstream side of the flash tank 20) of the binary power generator according to the embodiment.
In some embodiments, as shown in FIG. 2, the binary power generation device 1 allows the hot spring well 40 and a part of the hot spring water that has springed out from the hot spring well 40 to be deeper than the ground surface in the hot spring well 40. A pressure feeding means 50 for pressure feeding is further provided. And the hot spring water acquired from the hot spring well 40 is supplied to the flash tank 20 as hot water in which the crystallizable substance is dissolved. In addition, the hot spring well 40 may be comprised with the pipe formed from the material (for example, iron etc.) which is hard to corrode with a hot spring component.
In the exemplary embodiment shown in FIG. 2, the pumping means 50 includes a storage tank 52 for storing hot spring water springed out from the hot spring well 40, and a pumping flow path 56 for sending hot spring water from the storage tank 52 to the underground. And a pump 54 for sending hot water at an appropriate flow rate from the storage tank 52 to the pressure feed passage 56 so as to obtain a desired rising speed of the hot spring water.
When pumping part of the hot spring water springed out from the hot spring well 40 by the pumping means 42, the rising speed in the vertical upward direction of the hot spring water in the hot spring well 40 is 1.5 m / s or more at the height of the ground surface. As such, it may be pumped. If it is such an ascending speed, it is easy to suppress the retention and coupling | bonding of the crystallized substance (scale) in the hot spring well 40. FIG.

The reason why the scale precipitates and binds in the hot spring well and the reason why the scale binding can be suppressed by using the pumping means as described above are considered as follows.
Generally, in hot spring wells of hot springs where crystallized substances are dissolved, the pressure decreases as the hot spring water rises from the hot spring vein deep underground and approaches the ground surface, so in the vicinity of the ground surface (for example, 0-30 m below ground). Crystallized matter (so-called scale) may be precipitated. That is, as the hot spring water under high pressure in the deep underground rises toward the surface of the earth, the pressure decreases, the CO ₂ gas that can be dissolved in the hot spring water decreases, and the liberation of CO ₂ gas proceeds (2HCO ₃ ⁻ → CO ₃ ²⁻ + CO ₂ ↑ + H ₂ O). As a result, the amount of _CO ^{3 2-} ions present in the hot water is increased, which CaCO ₃ is precipitated in combination with ^{Ca 2+} ions of hot water ^{_{(Ca 2+ + CO 3 2- →}} CaCO 3 ↓). Further, when the hot spring water contains calcium sulfate (CaSO ₄ ), the calcium sulfate is considered to have a function as a binder that binds the precipitated CaCO ₃ . Therefore, if this state is left as it is, precipitation of crystallized matter proceeds in the hot spring well, and the precipitates are combined to cause clogging of the hot spring well.

In the binary power generation apparatus 1 according to the above-described embodiment, the hot-spring water rises in the hot-spring well 40 by pumping a part of the hot-spring water springed out from the hot-spring well 40 to a portion deeper than the ground surface by the pumping means 50. Since the speed is increased, retention of hot spring water and precipitated CaCO ₃ can be suppressed. Therefore, in the hot spring well 40, precipitated CaCO ₃ it is possible to suppress to be bound by the binder component, such as CaSO ₄ that is included in the hot spring water, is possible to prevent or suppress the hot spring well 40 is clogged It is considered possible.
Moreover, in the binary electric power generating apparatus 1 which concerns on the above-mentioned embodiment, since the pumping means 50 pumps a part of hot spring water which came out from the hot spring well 40, the temperature fall in the hot spring well 40 can be suppressed to the minimum. . CaCO ₃ is considered to be able to reduce precipitation of CaCO ₃ because the amount of CaCO ₃ dissolved in water becomes larger at higher temperatures.

A part of the hot spring water that springs out from the hot spring well 40 may be pumped to a depth of 10 to 30 m below the ground. In the exemplary embodiment shown in FIG. 2, the pumping flow path 56 may be provided to a depth of 10 to 30 m underground. Empirically, it is known that scale deposition occurs in the vicinity of 10 to 20 m below the ground. By pumping the hot spring water to the above depth, the stagnation and bonding of the scale in the hot spring well 40 can be effectively suppressed.
In addition, as shown in FIG. 2, since the hot spring water springed out from the hot spring well 40 is liberated under atmospheric pressure, CO _{2 and the} like are liberated, so that a crystallization product 59 such as CaCO ₃ may be precipitated. In order to remove such crystallized matter 59 from the hot spring water in the storage tank 52, a mesh filter 58 may be used.
Moreover, as shown in FIG. 2, the hot spring water stored in the storage tank 52 may be supplied to the flash tank 20 of the binary power generator 1 using a pump 51 or the like, as shown in FIG. Alternatively, it may be supplied directly from the hot spring well 40 without going through a storage tank or the like.

  A binary power generation method according to an embodiment is a binary power generation method in which a generator is driven by a working fluid, and includes a decompression step, a heat exchange step, and a power generation step.

In the depressurization step, the hot water in which the crystallizable substance is dissolved is depressurized to precipitate the crystallizable substance, and the hot water is converted into steam having a temperature lower than that of the hot water and hot water having a temperature lower than that of the hot water. To separate.
In some embodiments, the hot water in which the crystallizable substance is dissolved may be decompressed using the flash tank 34 shown in FIG. Moreover, you may adjust the pressure in the flash tank 34 so that it may become an appropriate value using the 1st flow regulating valve 24 shown in FIG.

In the heat exchange step, the working fluid is evaporated by heat exchange with steam.
In some embodiments, heat exchange between the working fluid and the above may be performed using 6 for the thermal effect shown in FIG.

  In the power generation process, the generator is driven by expanding the evaporated working fluid by the expander and rotating the rotating shaft of the expander.

  The binary power generation method according to an embodiment may be performed by the binary power generation apparatus 1 illustrated in FIG.

  In some embodiments, hot water obtained from a hot spring well may be used as hot water used in the decompression step.

In some embodiments, a pressure feeding step is provided before the pressure reducing step.
In the pumping process, a part of the hot spring water that has springed out from the hot spring well is placed in the hot spring well so that the vertical upward speed of the hot spring water in the hot spring well is 1.5 m / s or more on the ground surface. Pumped deeper than the ground surface.
In some embodiments, the pumping means 50 shown in FIG. 2 may be used to pump hot spring water to a deep portion in the hot spring well in the pumping step.

DESCRIPTION OF SYMBOLS 1 Binary power generator 2 Generator 4 Expander 6 Heat exchanger 8 Circulation line 10 Condenser 12 Pump 20 Flash tank 22 Supply line 24 1st flow regulating valve 26 Discharge line 28 2nd flow regulating valve 32 Condenser 34 Separator 35 Vacuum pump 40 Hot spring well 50 Pressure feeding means

Claims (6)

A generator,
An expander having a rotating shaft connected to the generator;
A heat exchanger for evaporating the working fluid;
A circulation line configured to circulate the working fluid through the heat exchanger and the expander, and
A binary power generator configured to drive the generator by rotating the rotating shaft by expanding the working fluid evaporated in the heat exchanger with the expander;
Depressurizing hot water in which the crystallizable substance is dissolved to precipitate the crystallizable substance and separating the hot water into steam having a temperature lower than that of the hot water and hot water having a temperature lower than that of the hot water. A flash tank,
A supply line for supplying the hot water to the flash tank;
A first flow rate adjustment valve provided in the supply line for adjusting the flow rate of the hot water supplied to the flash tank;
The heat exchanger is configured to receive the supply of the steam flowing out from the flash tank and evaporate the working fluid by heat exchange with the steam ,
The binary power generator configured to adjust the flow rate of the hot water so that the pressure of the flash tank is set to a pressure at which the crystallizable substance is precipitated . A discharge line for discharging the warm water from the flash tank;
The binary power generator according to claim 1, further comprising: a second flow rate adjustment valve provided in the discharge line for adjusting a flow rate of the hot water discharged from the flash tank.   The binary power generator according to claim 1 or 2, wherein the crystallizable substance is calcium carbonate. A hot spring well,
A part of the hot spring water erupted from the hot spring well is placed in the hot spring well so that the vertical rising speed of the hot spring water in the hot spring well is 1.5 m / s or more at the height of the ground surface. Further comprising a pumping means for pumping to a portion deeper than the ground surface,
The binary power generator according to any one of claims 1 to 3, wherein the hot water is hot spring water obtained from the hot spring well. A binary power generation method in which a generator is driven by a working fluid,
The hot water in which the crystallizable substance is dissolved is decompressed in a flash tank to precipitate the crystallizable substance, and the hot water is separated into steam having a temperature lower than that of the hot water and hot water having a temperature lower than that of the hot water. A depressurizing step,
A heat exchange step of guiding the steam flowing out of the flash tank to a heat exchanger, and evaporating the working fluid by heat exchange with the steam in the heat exchanger;
A power generation step of driving the generator by expanding the evaporated working fluid with an expander and rotating a rotating shaft of the expander , and
The binary power generation method , wherein in the decompression step, the supply amount of the hot water to the flash tank is adjusted so that the pressure of the flash tank is set to a pressure at which the precipitation of the crystallizable substance occurs . The hot water is hot spring water obtained from a hot spring well,
Before the depressurization step, the hot spring water that has springed out from the hot spring well so that the rising speed in the vertical upward direction of the hot spring water in the hot spring well is 1.5 m / s or more at the height of the ground surface. The binary power generation method according to claim 5, further comprising a pumping step of pumping the section to a portion deeper than a ground surface in the hot spring well.

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