JP2014134106A - Geothermal power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a geothermal power generation system capable of increasing an amount of steam supplied to a steam turbine and increasing power generation amount without increasing the flow volume of gas-water mixture fluid of hot water and the steam pumped up from the underground.SOLUTION: An absorption heat pump including a regenerator 63, a condenser 64, an evaporator 61, an absorber 62, and the like; a high-pressure gas-water separator 51H; and high-pressure steam turbine 52H are installed in a conventional geothermal power generation system. A conventional gas-water separator and a conventional steam turbine are used as a low-pressure gas-water separator 51L and a low-pressure steam turbine 52L, respectively. A geothermal power generation system with the absorption heat pump absorbs heat from the hot water returned to the underground, generates high-temperature heat, heats the hot water pumped up from the underground with this heat, and generates high-temperature high-pressure steam. The generated steam is supplied first to the high-pressure steam turbine 52H and then to the low-pressure steam turbine 52L. The steam generated when the hot water is pumped up from the underground is supplied to the low-pressure steam turbine 52L.

Description

The present invention relates to a geothermal power generation system that supplies only steam that heats hot water from the ground using a heat pump to increase power generation to a steam turbine.

The prior art geothermal power generation system has the advantage that fuel is not required compared to a thermal power generation system, but the steam flow per unit of power generation is large because the temperature and pressure of the steam supplied to the steam turbine are low. However, there is a disadvantage that the device cost becomes high.

In the prior art, there are known examples of improving the operation of air conditioning and hot water supply by combining a heat pump for air conditioning and hot water supply with a geothermal power generation system, but hot water pumped from the ground using a heat pump is heated to the steam turbine. There is no known example of increasing the flow rate of the supplied steam.

In addition, there is a known example of a power generation system that combines a heat pump with a system that uses solar heat instead of geothermal heat, but there is no description in this known example of increasing the flow rate of steam supplied to a steam turbine using a heat pump.

JP 2012-251456 A JP 2012-225313 A JP 2006-170072 A JP 2011-69233 A

Hachijojima Geothermal / Wind Power Plant-TEPCO Homepage, Geothermal Power Plant, Mechanism of Geothermal Power Generation (http://www.tepco.co.jp/hachijojima-gp/hachijo/g-03-J.html)

A problem to be solved is to provide a geothermal power generation system capable of increasing the power generation amount without increasing the flow rate of the air-water mixed fluid pumped from the ground in a geothermal power generation system that supplies only steam to the steam turbine. There is.

The challenge is to install a heat pump, absorb the heat of the hot water returned to the ground, create high-temperature heat, and boil the hot water pumped from the ground using this high-temperature heat. This can be solved by increasing the flow rate of steam supplied to and increasing the temperature and pressure.

As the heat pump, a compression heat pump or an absorption heat pump is used.

According to the present invention, the power generation amount can be increased without increasing the flow rate of the hot-water and steam-air mixed fluid that is pumped from the ground, so the size of the geothermal power generation system per unit of power generation is reduced. As a result, the apparatus cost is reduced, and the power generation cost is reduced.

1 is a schematic diagram of a geothermal power generation system having a compression heat pump according to Embodiment 1 of the present invention. The schematic of the geothermal power generation system which has an absorption heat pump by Example 2 of this invention. The schematic of the geothermal power generation system which has an absorption heat pump by Example 3 of this invention.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a geothermal power generation system having a compression heat pump according to a first embodiment of the present invention. The geothermal power generation system according to the first embodiment of the present invention generally includes a steam / water separator 11, a steam turbine 12, a generator 13, a condenser 14, a cooling tower 15, a condensate pump 16, a hot water pit 17, and reduced water. Equipment constituting the geothermal power generation system main body such as the pump 18 and the gas extractor 19, equipment constituting the compression heat pump constituted by the evaporator 21, the condenser 22, the compressor 23, the expansion valve 24, and the like, and circulation The pump 26 is configured.

As the heat medium of the compression heat pump, water, carbon dioxide gas, or chlorofluorocarbon fluid that easily changes in gas-liquid phase in a temperature range from room temperature to about 200 ° C. is used.

The steam / hot water steam-water mixed fluid M11 pumped from the ground is supplied to the steam / water separator 11 and separated into steam S11 and hot water W11.

In the evaporator 21, the liquid phase heat medium H <b> 21 is heated by the hot water W <b> 23 from the steam separator 11 and changes to a gas phase. The gas phase heat medium H22 is compressed by the compressor 23 to become a high temperature gas phase heat medium H23. This high-temperature gas phase heat medium H23 is cooled by the hot water W21 in the condenser 22 to become a liquid phase heat medium H24. The liquid phase heat medium H24 is decompressed when passing through the expansion valve 24, becomes a low temperature liquid phase heat medium H21, and is returned to the evaporator 21.

The hot water W21 from the steam separator 11 is transferred to the condenser 22 by the circulation pump 26, heated and boiled by the high-temperature gas phase heat medium H23, and becomes the steam-water mixed fluid M22. Returned to Further, the hot water W23 from the steam separator 11 is transferred to the evaporator 21, where the liquid phase heat medium H21 is heated in the evaporator 22 and is cooled to become hot water W24 having a lowered temperature. It is discharged into the pit 17.

The steam S11 in the steam separator 11 is supplied to the steam turbine 12 to drive the steam turbine 12 and generate electric power from the interlocking generator 13. The steam S12 exiting the steam turbine 12 is cooled in the condenser 14 to become condensed water C11, and then discharged to the hot water pit 17 through the cooling tower 15.

The hot water W24 and the condensed water C12 discharged to the hot water pit 17 are returned to the ground by the reduced water pump 18.

The flow rate of the steam S11 supplied to the steam turbine 12 of the geothermal power generation system according to the first embodiment of the present invention is generated by heat exchange in the condenser 22 rather than the flow rate of steam supplied to the steam turbine of the geothermal power generation system according to the prior art. The steam flow to be increased.

The amount of power generated by the geothermal power generation system according to the first embodiment of the present invention is larger than the amount of power generated by the conventional geothermal power generation system because the flow rate of steam supplied to the steam turbine increases.

For example, as shown in Table 1, the power generation amount obtained under the condition of pumping hot water at a temperature of 150 ° C. (saturation pressure 0.48 MPa) in the underground at 100 tons per hour is about 450 kW in the conventional geothermal power generation system. However, it increases to about 1,5000 kW in the geothermal power generation system according to the first embodiment of the present invention.

However, in the geothermal power generation system according to the first embodiment of the present invention, since the compressor uses about 660 kW of electric power, the power generation amount of the system is about 840 kW under the condition that other auxiliary power is ignored.

The geothermal power generation system according to the first embodiment of the present invention has a drawback that the generated power from the generator increases, but the amount of power generated by the entire system does not increase sufficiently because it has a compressor that uses a large amount of power.

For this reason, the subject which provides the geothermal power generation system with small electric power used remains in the geothermal power generation system by Example 1 of this invention.

The problem of providing a geothermal power generation system with low power consumption is solved by using an absorption heat pump instead of a compression heat pump.

FIG. 2 is a schematic diagram of a geothermal power generation system using an absorption heat pump according to a second embodiment of the present invention. The geothermal power generation system using the absorption heat pump according to the second embodiment of the present invention generally includes a steam / water separator 31, a steam turbine 32, a generator 33, a condenser 34, a condensate pump 35, a cooling tower 36, a heat Consists of equipment constituting the geothermal power generation system main body such as water pit 37, reduced water pump 38, gas extractor 39, evaporator 41, absorber 42, regenerator 43, condenser 44, heat exchanger 45, etc. It is comprised from the apparatus which comprises an absorption heat pump, and the circulation pump 46 grade | etc.,.

In the combination of the heat medium and the absorption liquid used in the absorption heat pump, the absorption of the vapor phase heat medium into the absorption liquid and the release of the vapor phase heat medium from the absorption liquid are easily performed in the temperature range from room temperature to about 200 ° C. Required characteristics. For this reason, the heat medium is water and the absorbent is a combination of lithium bromide aqueous solutions, or the heat medium is ammonia and the absorbent is a combination of water.

The steam / hot water / water mixed fluid M31 in the ground is supplied to the steam / water separator 31 and separated into steam S31 and hot water W31.

In the evaporator 41, the liquid phase heat medium H41 is heated by the hot water W43 from the steam separator 31 to be changed into a gas phase, and the gas phase heat medium H42 is supplied to the absorber 42. At this time, since the hot water W43 is cooled by the liquid-phase heat medium H43, the hot water W44 has a lowered temperature.

In the absorber 42, the gas phase heat medium H42 is absorbed by the absorbing liquid H43 cooled by the hot water W41 from the steam separator 31. At this time, since the hot water W41 is heated from the absorbing liquid H43, it boils and becomes a gas-liquid mixed fluid M42 of steam and hot water. The absorbing liquid H44 that has absorbed the gas phase heat medium H42 is supplied to the regenerator 43 via the heat exchanger 45.

In the regenerator 43, the absorbing liquid H <b> 44 is heated and boiled by the hot water W <b> 44 that has passed through the evaporator 41, and releases the gas phase heat medium absorbed in the absorber 42. The absorbing liquid H43 that has released the gas phase heat medium H45 is returned to the absorber 42 through the heat exchanger 45.

The gas phase heat medium H45 generated in the regenerator 43 is supplied to the condenser 44, cooled by the cooling fluid CW41, and becomes the liquid phase heat medium H41. The liquid phase heat medium H41 is returned to the evaporator 41. As the cooling fluid CW41, groundwater, river water, seawater, water from a cooling tower, or air is used.

The hot water W41 transferred from the steam-water separator 31 to the absorber 42 is heated to become the steam-water mixed fluid M42 and returned to the steam-water separator 31. Further, the hot water W43 transferred from the steam separator 31 to the evaporator 41 is cooled to lower the temperature, and subsequently cooled in the regenerator 43 to further decrease the temperature. To be drained.

The steam S31 in the steam separator 31 is supplied to the steam turbine 32 to drive the steam turbine 32 and generate electric power from the associated generator 33. The steam S32 exiting the steam turbine 32 is cooled in the condenser 34 to become condensed water C31, and then discharged to the hot water pit 37 through the cooling tower 36.

The hot water W45 and the condensed water C32 discharged to the hot water pit 37 are returned to the ground by the reduced water pump 48.

The flow rate of the steam S31 supplied to the steam turbine 32 of the geothermal power generation system according to the second embodiment of the present invention is the flow rate of the steam S11 supplied to the steam turbine 12 of the geothermal power generation system according to the first embodiment of the present invention. To approximate. For this reason, the electric power generation amount from the generator 33 also approximates the electric power generation amount from the generator 13 of the geothermal power generation system which becomes Example 1 of this invention mentioned above.

Therefore, since the amount of power generation of the geothermal power generation system according to the second embodiment of the present invention does not require a compressor, the power generation amount of the geothermal power generation system according to the first embodiment is roughly equivalent to the amount of power used by the compressor. Will increase.

For example, as shown in Table 1, in the condition that geothermal power generation is performed by pumping up 100 tons of hot water at a temperature of 150 ° C. (saturation pressure 0.48 MPa) in the ground, The amount of power generated by the geothermal power generation system according to the second embodiment of the invention is 1,480 kW.

Furthermore, the problem of generating more power than the geothermal power generation system according to the second embodiment of the present invention is solved by increasing the pressure and temperature of the steam supplied to the steam turbine.

Increasing the pressure and temperature of the steam supplied to the steam turbine replaces the circulation pump 46 that only circulated hot water with a pump capable of boosting the pressure, and the steam separator is replaced with a high pressure steam separator and a low pressure steam. Multiple water separators, multiple steam turbines, high pressure steam turbines and low pressure steam turbines, supply steam from high pressure steam separator to high pressure steam turbine, and supply steam from low pressure steam separator to low pressure steam turbine Is achieved.

FIG. 3 is a schematic diagram of a geothermal power generation system using an absorption heat pump according to a third embodiment of the present invention. The geothermal power generation system using the absorption heat pump according to the third embodiment of the present invention includes a high pressure steam / water separator 51H, a low pressure steam / water separator 51L, a high pressure steam turbine 52H, a low pressure steam turbine 52L, a generator 53, and a condenser. 54, cooling tower 55, condensate pump 56, hot water pit 57, reducing water pump 58, equipment constituting the main body of the geothermal power generation system such as gas extractor 59, evaporator 61, absorber 62, regenerator 63, It is comprised from the apparatus which comprises the absorption heat pump comprised from the condenser 64, the heat exchanger 65, etc., and the pressure | voltage rise pump 66.

In the combination of the heat medium and the absorption liquid used in the absorption heat pump, the absorption of the vapor phase heat medium into the absorption liquid and the release of the vapor phase heat medium from the absorption liquid are easily performed in the temperature range from room temperature to about 200 ° C. Required characteristics. For this reason, the heat medium is water and the absorbing solution is a lithium bromide aqueous solution, or the heat medium is ammonia and the absorbing solution is a combination of water.

The steam / hot water / water mixed fluid M51 in the ground is supplied to the low pressure steam / water separator 51L and separated into steam and hot water. In the evaporator 61, the liquid phase heat medium H61 is heated by the hot water W63 from the low-pressure steam-water separator 51L to be changed into a gas phase, and the gas phase heat medium H62 is supplied to the absorber 62. At this time, since the hot water W63 is cooled by the liquid phase heat medium H63, the hot water W64 has a reduced temperature.

In the absorber 62, the gas phase heat medium H62 is absorbed by the absorbing liquid H63 cooled by the hot water W61 from the low pressure steam-water separator 51L. At this time, since the hot water W61 from the low pressure steam-water separator 51L is heated from the absorbing liquid H63, it becomes a gas-liquid mixed fluid M62 of steam and hot water. The absorbing liquid H64 that has absorbed the gas phase heat medium H62 is supplied to the regenerator 63 via the heat exchanger 65.

In the regenerator 63, the absorbing liquid H <b> 64 is heated and boiled by the hot water W <b> 64 that has passed through the evaporator 61, and releases the vapor phase heat medium that has been absorbed by the absorber 62. The absorbing liquid H63 that has released the gas phase heat medium H65 is returned to the absorber 62 through the heat exchanger 65.

The vapor phase heat medium H65 generated in the regenerator 63 is supplied to the condenser 64, cooled by the cooling fluid CW61, and becomes the liquid phase heat medium H61. The liquid phase heat medium H61 is returned to the evaporator 61. As the cooling fluid CW61, groundwater, river water, seawater, water from a cooling tower, or air is used.

The hot water W61 transferred from the low pressure steam / water separator 51L to the absorber 62 is heated to become a steam / water mixed fluid M62 and supplied to the high pressure steam / water separator 51H. Further, the hot water W63 transferred from the low-pressure steam-water separator 51L to the evaporator 61 is cooled to lower the temperature, and subsequently cooled in the regenerator 63 to lower the temperature. To be drained.

The steam-water mixed fluid M62 from the absorber 62 is separated into steam S51H and hot water W51H in the high-pressure steam-water separator 51H. The steam S51H in the high-pressure steam separator 51H is supplied to the high-pressure steam turbine 52H, drives the high-pressure steam turbine 52H, and generates electric power from the generator 53. The steam S52H that has exited the high-pressure steam turbine 52H is supplied to the low-pressure steam turbine 52L and used to generate electric power from the generator 53.

Hot water W51H in the high pressure steam separator 51H is supplied to the low pressure steam separator 51L. At this time, since the pressure is reduced, it becomes an air-water mixed fluid of steam and hot water.

The steam S51L in the low-pressure steam separator 51L is supplied to the low-pressure steam turbine 52L to drive the low-pressure steam turbine 52L, and generates electric power from the associated generator 53. The steam S52L exiting the low-pressure steam turbine 52L is cooled in the condenser 53 to become condensed water C51, and then discharged to the hot water pit 57 through the cooling tower 56.

The hot water W65 that has passed through the evaporator 61 and the regenerator 63 discharged to the hot water pit 57 and the condensed water C52 that has passed through the cooling tower 56 are returned to the ground by a reducing water pump 68.

The power generation amount of the geothermal power generation system according to the third embodiment of the present invention is the sum of the power amount generated when the high-pressure steam turbine 52H is driven and the power amount generated when the low-pressure steam turbine 52L is driven.

In the geothermal power generation system according to the third embodiment of the present invention, the flow rate, temperature and pressure of the steam S51H supplied to the low pressure steam turbine 52L are close to the flow rate, temperature and pressure of the steam supplied to the steam turbine 32 in the second embodiment. To do. Therefore, the amount of electric power generated by driving the low-pressure steam turbine 52L in the geothermal power generation system according to Embodiment 3 of the present invention is close to the amount of electric power generated by driving the steam turbine 32 of the geothermal power generation system according to Embodiment 2 of the present invention. To do.

Therefore, the amount of power generated by the geothermal power generation system according to the third embodiment of the present invention is greater than the amount of power generated by the geothermal power generation system according to the second embodiment of the present invention by driving the high-pressure steam turbine 52H.

For example, as shown in Table 1, when the auxiliary power is ignored under the condition that the geothermal power is generated by pumping up 100 tons of hot water at a temperature of 150 ° C. (saturation pressure 0.48 MPa) in the ground as shown in Table 1. The power generation amount of the geothermal power generation system of Example 2 is about 1,480 kW, but the power generation amount of Example 3 of the present invention increases to about 1,580 kW.

The steam turbine has a problem that the flow of steam becomes unstable when the dryness in the steam decreases. This problem can be solved by increasing the degree of superheat (steam temperature-saturation temperature) of the steam supplied to the steam turbine.

Increasing the degree of superheat of the steam supplied to the steam turbine can be achieved by reheating the steam S52H emitted from the high-pressure steam turbine 52H with the hot water W51H in the high-pressure steam-water separator 51L.

The steam supplied to the low-pressure steam turbine 52L is heated to a temperature close to that of the hot water W51H, so that the dryness of the steam in the low-pressure steam turbine is improved and the unstable steam flow is suppressed. Become.

The geothermal power generation system combined with the heat pump according to the present invention can be applied to new and existing geothermal power generation systems, and can also be applied to power generation systems using solar heat and factory exhaust heat.

51H: High pressure steam separator, 51L: Low pressure steam separator, 52H: High pressure steam turbine, 52L: Low pressure steam turbine, 53: Generator, 54: Condenser, 55: Cooling tower, 56: Condensate pump, 57: Hot water pit, 58: Reduced water pump, 59: Gas extractor, 61: Evaporator, 62: Absorber, 63: Regenerator, 64: Condenser, 65: Heat exchanger, 66: Booster pump, S51H : High-pressure steam, S51L: Low-pressure steam, S52H: High-pressure steam, S52L: Low-pressure steam, C51: Condensed water, M51: Gas-liquid mixed fluid, M62: Gas-liquid mixed fluid, W51H: Hot water, W51L: Hot water, W61: Hot water, W62: Hot water, W63: Hot water, W64: Hot water, W65: Hot water, H61: Liquid phase heat medium, H62: Gas phase heat medium, H63: Absorption liquid, H64: Absorption liquid, H65: Gas Phase heat medium, CW61: Cooling fluid

Claims (6)

A steam / water separator that separates the steam-and-water mixed fluid from the ground into steam and hot water, a steam turbine that is supplied with steam, a generator that works in conjunction with the steam turbine, a condenser that condenses steam that exits the steam turbine, Geothermal heat, comprising an evaporator for exchanging heat between the hot water and the liquid phase heat medium, a condenser for exchanging heat between the hot water and the gas phase heat medium, and a compressor for compressing the gas phase heat medium. Power generation system. The geothermal power generation system according to claim 1, wherein the heat medium is water, carbon dioxide gas, or a fluorocarbon fluid. A steam / water separator that separates the steam-and-water mixed fluid from the ground into steam and hot water, a steam turbine that is supplied with steam, a generator that works in conjunction with the steam turbine, a condenser that condenses steam that exits the steam turbine, An evaporator that exchanges heat between the hot water and the liquid phase heat exchanger, an absorber that absorbs the gas phase heat medium into the absorption liquid that exchanges heat with the hot water, and a gas phase heat medium from the absorption liquid that exchanges heat with the hot water. A geothermal power generation system comprising a regenerator that generates gas and a condenser that condenses a gaseous heat medium. A high pressure steam / water separator that separates the steam / water mixture into steam and hot water, a high pressure steam turbine that is supplied with steam from the steam / hot water separator, and a steam / hot fluid separated from the ground into steam and hot water Low-pressure steam / water separator, low-pressure steam turbine to which steam from the low-pressure steam / water separator is supplied, high-pressure steam turbine, generator coupled to the low-pressure steam turbine, condenser for condensing steam from the low-pressure steam turbine , An evaporator that exchanges heat between the hot water and the liquid phase heat exchanger, an absorber that absorbs the gas phase heat medium into the absorbing liquid that exchanges heat with the hot water, and heat in the gas phase from the absorbing liquid that exchanges heat with the hot water A geothermal power generation system comprising a regenerator for generating a medium and a condenser for condensing a gas phase heat medium. 5. The geothermal power generation system according to claim 4, wherein the steam exiting the high-pressure steam turbine is supplied to the low-pressure steam turbine after heat exchange with hot water in the high-pressure steam-water separator. 6. The heat medium is water and the absorption liquid is an aqueous lithium bromide solution, or the heat medium is ammonia and the absorption liquid is water. Geothermal power generation system.

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