JP2016205303A - Temperature drop compensation type geothermal heat exchanger and temperature drop compensation type geothermal power generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature drop compensation type geothermal heat exchanger and a temperature drop compensation type geothermal power generator capable of preventing steam temperature when boiling is carried out through reduction of pressure to attain steam from being decreased, removing disadvantage caused by liquefaction of steam and generating power of high output even under a relative low temperature region at a relative shallow depth.SOLUTION: A geothermal heat exchanger 1 comprises a water feeding pipe 2 that is arranged at an underground area and into which water is supplied from a ground surface, and a steam taking-out pipe 3 arranged at an underground to be contacted with the water feeding pipe 2. The steam taking-out pipe 3 is provided with a plurality of injection ports 5 at its lower region, and an interface lower region between the water feeding pipe 2 and the steam taking-out pipe 3 and an area provided with the injection ports 5 have a first heater 31 fixed thereto. High pressure hot water generated by supplying heat from the geothermal band in respect to water in the water feeding pipe 2 is converted into a steam uni-phase flow within the steam taking-out pipe 3 through the injection ports 5, and a reduction in temperature at the time of reduced pressure boiling is compensated by the first heater 31 and taken out to the ground.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature decrease compensation type geothermal exchanger and a temperature decrease compensation type geothermal power generation apparatus capable of efficiently extracting geothermal energy.

  Geothermal power generation using geothermal energy uses a high-temperature magma layer as a heat source and can be made into semi-permanent thermal energy and does not generate greenhouse gases in the process of power generation. In recent years, it has attracted attention as a fuel alternative.

  Conventional geothermal power generation generates electricity by boring the geotropics and using natural pressure to extract natural steam and hot water that exist in the geotropics. Therefore, the extracted steam and hot water contain a large amount of sulfur and other impurities peculiar to the earth and tropics. This impurity becomes a scale and adheres to a heat well, piping, a turbine, or the like. If the scale adheres, the power generation output decreases over time, making long-term use difficult.

  In order to solve the problem due to this scale, Patent Document 1 discloses a technique that employs a system in which water is sent from the ground and heated by heat supplied from the earth and the hot water is taken out.

  The technique described in Patent Document 1 is a method of taking out a high-pressure single-phase flow taken out by a geothermal exchanger installed underground as steam with a steam separator installed on the ground. It has a great effect in that it can effectively use geothermal heat while solving.

  The following problems can be considered regarding geothermal exchange. First, because of the pressure loss in the piping of the water that is sent underground and hot water that is extracted with the supply of geothermal heat, the power of the high-pressure pump must be increased. In order to raise, there is a problem that it is necessary to increase the diameter of the geothermal exchanger.

  Second, one of the advantages of Patent Document 1 is the replacement of existing wells, but the problem is that the wells to which replacement is applied are limited by limiting the diameter of the geothermal exchanger. There is. In addition to the replacement of existing wells, the size of the geothermal exchanger can be an obstacle when considering geothermal exploration wells, replacement of dormant wells, and the like.

  In Patent Document 2, the solution is to reduce the unit price of power generation by increasing the energy efficiency of the geothermal power generation system and suppressing the cost increase of pumps and the like. A steam generation method for geothermal power generation is described in which heat is absorbed in the geotrophic and the pressure of the liquid is reduced to a saturation vapor pressure or less while the liquid that has absorbed heat is raised from the geotropy. In addition, technologies related to geothermal power generation are described in Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6, Patent Literature 7, and Patent Literature 8.

JP 2011-52621 A Japanese Patent Laid-Open No. 2014-227962 JP-A-49-103122 JP-A-1-232175 Japanese Patent Publication No. 64-7227 JP 2014-84857 A JP 2014-47676 A JP 2011-169188 A

  According to the technology described in Patent Document 2, since the pressure of the liquid is reduced to the saturated vapor pressure or lower in the course of raising the heat-absorbing liquid from the earth, compared with the case where the pressurized hot water is raised. The problem that heat loss occurs between the hot water leaving the geothermal exchanger, the water to be fed, and the low-temperature underground zone is reduced to some extent.

  However, since the high-temperature steam is extracted through near the water to be fed and the low temperature underground, it is possible to suppress the heat exchange between the high temperature steam and the water to be fed and the low temperature underground as much as possible. It has been demanded.

When performing geothermal power generation, it is not easy to determine whether the underground geotrophic structure is rock or earth and sand containing pressure water, and searching for geothermal resources at pinpoints is not possible. Requires advanced exploration technology.
Moreover, like the thing described in patent document 2, when boiling and obtaining a vapor | steam by decompression, a vaporization heat component and a vapor | steam temperature fall. The latent heat in this vaporization is presupposed to be supplied from the geotropics, but due to the difference in thermal conductivity between the pipes that generate steam and geotropical rocks, etc. There may be a delay in supply. When a delay occurs in the heat supply, the steam temperature decreases due to this time difference.

  In addition, in order to widely disseminate geothermal power generation, a power generation system that is overwhelmingly distributed and capable of generating power even at relatively low temperatures at shallow depths is necessary. Is low, the turbine becomes large.

  Steam produced by ordinary geothermal power generation has a pressure slightly lower than the value on the saturation curve at the target temperature, and the steam is close to saturated steam. If the steam produced is close to saturated steam, the steam after work will easily liquefy. For this reason, steam is likely to condense when driving the turbine or heat exchanger, and if dew condensation occurs, the efficiency of the turbine is reduced and the durability is also affected.

  Regarding the generation of superheated steam, Patent Document 8 uses a solar heat collector that collects solar heat to heat water vapor collected from the ground to a temperature higher than the saturated steam temperature by heat exchange with the received solar heat. The production of superheated steam. According to this method, it is possible to generate superheated steam, but it is necessary to separately prepare a solar heat collector for collecting solar heat in addition to the geothermal exchanger, and the facility cannot be simplified.

  The present invention has been made to solve such problems, and prevents a drop in steam temperature when boiling to obtain steam by reducing pressure, and removes harmful effects caused by liquefaction of steam. This is a temperature drop compensation type geothermal exchanger and temperature drop compensation that can suppress the heat exchange between the high-temperature steam and the water being fed in and the low-temperature underground area, and can generate high power at a shallow depth and at relatively low temperatures. It aims at providing a type geothermal power generation device.

  In order to solve the above problems, a temperature decrease compensation type geothermal exchanger according to the present invention is provided in the ground so as to be in contact with the water injection pipe provided in the ground and supplied with water from the ground. A steam take-out pipe having a plurality of spouts, and a first heater attached to a region below the boundary between the water injection pipe and the steam take-out pipe and provided with the spout. The pressure in the steam extraction pipe is reduced below the pressure required by the turbine, and high-pressure hot water generated by supplying heat from the earth to the water in the water injection pipe passes through the jet outlet. The steam is converted into a steam single-phase flow in the steam take-out pipe, and the first heater is used to compensate for the temperature drop during boiling under reduced pressure, and is taken out to the ground.

  The water supplied to the water injection pipe becomes high-temperature pressure water substantially proportional to the depth from the ground at the lower part of the water injection pipe. Since the pressure in the steam extraction pipe is reduced to a pressure lower than that required by the turbine, the high-temperature pressure water is jetted to the steam extraction pipe through the outlet provided in the steam extraction pipe by the water pressure, and the pressure is reduced. It is converted into a steam single-phase flow in the steam extraction pipe, and this steam single-phase flow is taken out to the ground.

  The steam in the steam take-out pipe moves to a turbine having a pressure gradient, and then expands in the turbine to become power for turning the turbine. The steam that exits the turbine returns to water in the condenser and is fed back into the water injection pipe. Since the amount of circulating water is equal to the amount of steam required by the turbine, the amount of circulating water is very small. By repeating this process, geothermal heat can be extracted efficiently and continuously. By performing geothermal exchange in this way, heat loss that occurs when passing through a low temperature zone is small, pipe loss due to friction when passing through the pipe surface is small, and heat that can reduce the amount of water to be circulated Exchange is possible.

  A first heater is attached to a region below the boundary between the water injection pipe and the steam take-out pipe and provided with a jet port, and this first heater reduces the temperature drop at the time of boiling under reduced pressure. Compensated. The latent heat during vaporization is based on the assumption that the geotropics have sufficient heat capacity and are supplied from the geotropics, but this is due to the difference in thermal conductivity between the pipes that generate steam and geotropical rocks, etc. If there is a delay in the heat supply from the earth and the tropics, the steam temperature decreases due to this time difference. Therefore, by compensating for the temperature drop at the time of boiling under reduced pressure by the first heater, it is possible to prevent the steam temperature from being lowered and contribute to the improvement of the output. As described above, the first heater has a function of compensating for a drop in steam temperature at the time of boiling under reduced pressure, and can be heated using a part of the power generation output. Since the steam produced by heating in the tropics is close to saturated steam, the steam after work is easily liquefied, but liquefaction can be prevented by using the first heater.

  Further, by raising the temperature of the produced steam, the steam can be converted from the saturated steam region to the superheated steam region. In general geothermal power generation, since the steam pressure and temperature are low, the turbine becomes large, but by using high-temperature and high-pressure superheated steam, the turbine can be made smaller and more efficient.

  In the temperature decrease compensation type geothermal exchanger of the present invention, a blower is attached to the outlet side of the steam extraction pipe or in a steam system from the steam generation section to the turbine, and the steam taken out from the steam extraction pipe is blower Can be boosted by.

  When steam is produced by boiling under reduced pressure, the pressure for boiling under reduced pressure is close to the pressure required by the turbine. When this steam is boosted by the blower, the pressure on the suction side of the blower becomes a value obtained by subtracting the blower pressure from the turbine pressure, and the pressure at the steam discharge section at the bottom of the steam extraction pipe is lower than the saturated steam pressure by the blower pressure. . As a result, an effect of moving the steam from the saturated steam to the superheated steam region and a synergistic effect of assisting the vaporization of the steam are produced. Moreover, since the pressure supplied to the turbine can be set high by increasing the blower pressure, a greater effect can be obtained. The power supply for boosting can use a part of the power generation output.

  In the temperature decrease compensation type geothermal exchanger of the present invention, the power generation output can be controlled by controlling the rotational speed of the blower.

  Since the flow rate of steam is proportional to the rotational speed of the blower, the output of the turbine can be controlled by controlling the rotational speed of the blower. Although there is a time delay, it is impossible to cope with sudden load fluctuations. However, when it is desired to control the power generation amount in time, programmed power generation in which the power generation amount is programmed is possible.

  In the temperature decrease compensation type geothermal exchanger of the present invention, a second heater is attached to the outlet side of the steam extraction pipe or in the steam system from the steam generation section to the turbine, and is taken out from the steam extraction pipe. The steam to be heated can be heated by a second heater.

  By heating the steam with the second heater, high-temperature and high-pressure superheated steam can be obtained. Therefore, the inlet temperature of the turbine can be set high, and the output and efficiency of the turbine can be improved. Moreover, since it is possible to prevent the steam from returning to water in the turbine, it is possible to maintain a state in which the steam driving the turbine or the heat exchanger is difficult to condense. The power source for heating can use a part of the power generation output.

  In the temperature decrease compensation type geothermal exchanger of the present invention, the steam extraction pipe is disposed inside the water injection pipe, and the diameter of the steam extraction pipe is reduced from the lower side of the geotropical side toward the upper side of the ground surface. The steam extraction pipe may be formed in the structure.

  As the steam extraction pipe is formed so that the diameter of the steam extraction pipe decreases from the lower part of the earth and the tropics toward the upper part of the surface of the earth, the single-phase steam flows in the steam extraction pipe as it approaches the low temperature region near the surface. As the speed increases, the passage time is shortened. The flow rate when the steam rises increases in inverse proportion to the square of the diameter of the steam extraction pipe, and the transit time required for the rise of the steam decreases in proportion to the square of the diameter of the steam extraction pipe. Furthermore, since the contact area with the water injection pipe that is the outer pipe decreases in proportion to the diameter of the steam extraction pipe, the amount of heat exchanged with the water injection pipe that is the outer pipe is the inner pipe. Since it decreases in proportion to the cube of the diameter of a certain steam extraction pipe, it is possible to reduce heat loss when the steam single-phase flow passes through the low temperature region.

  In addition, after installing the water injection pipe, which is the outer pipe, when installing the steam extraction pipe, which is the inner pipe, the diameter of the steam extraction pipe should be smaller from the lower side of the tropical zone to the upper side of the surface. Thus, the weight of the steam extraction pipe can be reduced as compared with the case where the steam extraction pipe is formed with the same diameter as that of the lower part of the geotropical side, and convenience during construction can be improved.

  In the temperature decrease compensation type geothermal exchanger according to the present invention, the diameter of the steam extraction pipe may be reduced stepwise from the geotropical side lower side toward the ground surface upper side.

  Moreover, in the temperature fall compensation type geothermal exchanger of this invention, the diameter of the said steam extraction pipe | tube can be set as the structure which becomes small continuously from the geotropical side lower part toward the surface upper part.

  In the temperature decrease compensation type geothermal exchanger according to the present invention, a heat insulating portion formed by forming an air layer above the water injection pipe by lowering a water level of the water supplied to the water injection pipe is It can be set as the structure provided with respect to the area | region which touches the low temperature zone near the surface.

  Depending on the target geothermal layer, the water pressure supplied to the geothermal exchanger installed in the ground may be too high, and if this water pressure needs to be lowered, the water level in the water injection pipe can be lowered to reduce the pressure inside the geothermal exchanger. The pressure can be adjusted. As a result, an air layer is formed in the upper part of the water injection tube, and a heat insulating effect can be obtained by the air layer having high heat insulating properties. In particular, when the depth of the high temperature zone of the well is large, an air layer can be formed in the water injection pipe in contact with the low temperature zone close to the ground surface by lowering the level of water supplied to the water injection pipe.

  In the temperature decrease compensation type geothermal exchanger of the present invention, a pressurizing pump for pressurizing the water supplied to the water injection pipe can be arranged on the ground.

  When large-capacity power generation is performed, the loss head of the outer pipe increases due to an increase in the amount of circulating water, but a pressure pump for pressurizing the water supplied to the water injection pipe is installed on the ground. By adopting such a configuration, it is possible to make up for the head loss and to obtain a larger pressure than in the case of natural water pressure, so that it is possible to realize a large-capacity power generation. Moreover, since the steam pressure can be increased by adopting a configuration in which a pressurizing pump for pressurizing the water supplied to the water injection pipe is disposed on the ground, it is possible to increase the temperature of unused high-temperature land throughout the country. The temperature drop compensation type geothermal exchanger of the present invention can be widely applied to the tropics.

  In the temperature decrease compensation type geothermal exchanger of the present invention, an insertion pipe formed by combining at least one water injection pipe and at least one steam extraction pipe is inserted into a plurality of geothermal wells. The outlets of the steam extraction pipes are connected in parallel, and the steam obtained by using the respective geothermal wells is collected in total, and the steam header for uniformizing the pressure of the collected steam is provided. be able to.

  Since the temperature and pressure are different depending on the place where the drilling is performed, the power generation output for one geothermal well differs when used for power generation. Therefore, by connecting the outlets of the steam extraction pipes of the insertion pipes in parallel to multiple geothermal wells and collecting the steam obtained using each geothermal well in total, the turbine, condenser, generator -The capacity of the transformer etc. can be designed large, and there is an advantage that the efficiency of the whole power plant is improved. Further, by arranging the steam header, the pressure of the collected steam can be made uniform.

  In the temperature decrease compensation type geothermal exchanger of the present invention, the geothermal well can be attached to an existing facility.

  Boring is newly performed by inserting and using an insertion pipe composed of a water injection pipe and a steam extraction pipe for an empty geothermal well or an inactive geothermal well attached to an existing facility. It is possible to take out the energy from hot water. In particular, since the diameter of the insertion tube can be reduced by taking it out from the ground as a vapor single-phase flow, the degree of freedom of the geothermal well that can be used is increased.

The temperature decrease compensation type geothermal power generation apparatus of the present invention is characterized in that power generation is performed using the temperature decrease compensation type geothermal exchanger of the present invention.
Moreover, the temperature fall compensation type geothermal power generation apparatus of this invention can perform the said electric power generation by a binary system.

  The temperature decrease compensation type geothermal exchanger of the present invention suppresses the occurrence of pressure loss and heat loss in the piping, makes it possible to reduce the diameter of the pipe embedded in the ground, and reduces the amount of water to be circulated. Because it can excel and has excellent heat exchange efficiency, by using this geothermal exchanger, it is possible to efficiently use geothermal wells attached to existing facilities and perform efficient geothermal power generation. Therefore, a highly convenient geothermal power generator can be realized.

  According to the present invention, the steam temperature is prevented from lowering when boiling by decompression to obtain steam, the harmful effects caused by the liquefaction of steam are removed, and the high temperature steam to be taken out, the water to be fed and the underground low temperature zone, Therefore, it is possible to realize a temperature decrease compensation type geothermal exchanger and a temperature decrease compensation type geothermal power generation apparatus capable of suppressing high-temperature heat exchange and capable of generating high output power even at a relatively shallow temperature at a shallow depth.

It is a figure which shows the temperature fall compensation type | mold geothermal exchanger and temperature fall compensation type | mold geothermal power generation apparatus which concern on 1st embodiment of this invention. It is a figure which shows the detail of a 1st heater. It is a figure which shows the temperature fall compensation type | mold geothermal exchanger and temperature fall compensation type | mold geothermal power generation apparatus which concern on 2nd embodiment of this invention. It is a figure which shows the temperature fall compensation type | mold geothermal exchanger and temperature fall compensation type | mold geothermal power generation apparatus which concern on 2nd embodiment of this invention. It is a figure which shows the temperature fall compensation type geothermal exchanger and temperature fall compensation type geothermal power generation apparatus which concern on 3rd embodiment of this invention. It is a figure which shows the structure of the temperature fall compensation type | mold geothermal power generation apparatus which applied the temperature fall compensation type | mold geothermal exchanger which concerns on 1st embodiment of this invention to the power generation of a binary system. It is a figure which shows the structure of the temperature fall compensation type | mold geothermal power generation apparatus which applied the temperature fall compensation type | mold geothermal exchanger which concerns on 2nd embodiment of this invention to binary power generation. It is a figure which shows the temperature fall compensation type | mold geothermal exchanger and temperature fall compensation type | mold geothermal power generator which concern on embodiment which pressurizes on the ground with respect to the water supplied to a water injection pipe.

Below, the temperature fall compensation type geothermal exchanger and temperature fall compensation type geothermal power generator of the present invention are explained based on the embodiment.
FIG. 1 shows a temperature decrease compensation type geothermal exchanger and a temperature decrease compensation type geothermal power generation apparatus according to the first embodiment of the present invention.

  In FIG. 1, the geothermal exchanger 1 includes a water injection pipe 2 provided in the ground and supplied with water from the ground, and a steam extraction pipe 3 provided in the ground so as to be in contact with the water injection pipe 2. ing. In FIG. 1, the water injection pipe 2 has an outer pipe close to the geotrophic 4 side, and the steam extraction pipe 3 has a double pipe structure with an inner pipe provided inside the water injection pipe 2. The steam extraction pipe 3 may be an outer pipe and the water injection pipe 2 may be an inner pipe.

  The steam outlet pipe 3 is provided with a plurality of jet outlets 5 in the lower region thereof, and the water injection pipe 2 and the steam outlet pipe 3 are opened by the jet outlet 5. That is, the jet nozzle 5 is provided at the boundary between the water injection pipe 2 and the steam extraction pipe 3. The steam extraction pipe 3 is connected to the turbine 6, and the pressure in the steam extraction pipe 3 is reduced to a pressure lower than that required by the turbine 6.

  The water supplied to the water injection pipe 2 by utilizing a natural head is applied with pressure almost proportional to the depth from the ground near the bottom of the water injection pipe 2, and heat is supplied from the geotropics 4. It becomes hot pressure water. Since the inside of the steam extraction pipe 3 is depressurized, using this pressure difference, as shown by the arrow, high-temperature pressure water is sprayed from the jet outlet 5 into the steam extraction pipe 3 in the spray state, and the turbine 6 is required. It is vaporized using the pressure difference between the pressure of the water and the bottom of the water injection pipe 2 and converted into a single-phase steam flow. The steam single-phase flow generated in the underground moves to the turbine 6 due to a pressure difference between the steam take-out pipe 3 and the turbine 6, and then expands in the turbine 6 to become power for turning the turbine 6. Power is generated by the generator 7 with this power.

  A first heater 31 is attached to a region below the boundary between the water injection pipe 2 and the steam take-out pipe 3 and provided with the jet port 5, and the first heater 31 reduces the pressure. Compensation for steam temperature drop during boiling. As a result, even if there is a delay in the heat supply from the geotropics due to the difference in thermal conductivity between the pipe that generates steam and the geotropical rocks, etc., the steam temperature can be prevented from lowering and the output can be improved. To do.

A blower 32 is attached to the outlet side of the steam extraction pipe 3, and the steam taken out from the steam extraction pipe 3 is boosted by the blower 32.
When the steam is boosted by the blower 32, the pressure on the suction side of the blower 32 becomes a numerical value obtained by subtracting the blower pressure from the turbine pressure, and the pressure at the bottom of the steam extraction pipe 3 is equal to the blower pressure than the saturated steam pressure. descend. As a result, an effect of moving the steam from the saturated steam to the superheated steam region and a synergistic effect of assisting the vaporization of the steam are produced. Moreover, since the pressure supplied to the turbine can be set high by increasing the blower pressure, a greater effect can be obtained. Further, the power generation output can be controlled by controlling the rotational speed of the blower 32.
In addition, the position where the blower 32 is attached is not limited to the outlet side of the steam extraction pipe 3 but can be in the steam system from the steam generating unit to the turbine.

A second heater 33 is attached to the outlet side of the steam extraction pipe 3, and the steam taken out from the steam extraction pipe 3 is heated by the second heater 33.
By heating the steam with the second heater 33, high-temperature and high-pressure superheated steam can be obtained. Therefore, the inlet temperature of the turbine 6 can be set high, and the output and efficiency of the turbine 6 can be improved. Moreover, since it is possible to prevent the steam from returning to water in the turbine 6, it is possible to maintain a state in which the steam that drives the turbine 6 or the heat exchanger does not easily condense.
In addition, the position where the second heater 33 is attached is not limited to the outlet side of the steam extraction pipe 3, but can be in the steam system from the steam generation unit to the turbine 6.
A part of the power generation output can be used as the power source of the first heater 31, the blower 32, and the second heater 33 described above. As a result, the power generation efficiency is slightly reduced, but high-temperature and high-pressure superheated steam can be produced, so that the output as a whole can be greatly improved.

  Thereafter, the steam exiting the turbine 6 is cooled by the cooling water 9 in the condenser 8 and returned to the water, and is supplied again to the water injection pipe 2. Since the amount of water to be circulated is equal to the amount of steam required by the turbine 6, the amount of water to be circulated is very small. By repeating this process, geothermal heat is continuously extracted. If necessary, the makeup water 11 is replenished from the makeup water tank 12 via the water treatment device 10. The makeup water level is adjusted by a makeup water control valve 13. A steam header 18 and a steam control valve 15 are provided between the steam take-out pipe 3 and the turbine 6. In addition, a pressure control valve 17 is provided.

  The steam header 18 is used when steam produced from a plurality of geothermal wells is collected and supplied to the single turbine 6, thereby making the pressure uniform.

  When the depth of the high temperature zone of the well is large, an air layer 19 is formed in the water injection pipe 2 in contact with the low temperature zone 26 close to the ground surface by lowering the level of the advanced treated water supplied to the water injection pipe 2. Therefore, this can improve the heat insulation effect. Moreover, the surface in contact with the high temperature zone at the lower part of the water injection pipe 2 is made of a material having excellent heat conduction characteristics so as to easily absorb the geothermal heat.

  When a major equipment accident such as the turbine 6 or the generator 7 or a power transmission system accident occurs, the circuit breaker of the generator 7 is activated. In this case, the pressure in the geothermal exchanger 1 increases rapidly. In order to prevent this, the emergency pressure reducing valve 16 can be operated to prevent a sudden pressure increase in the geothermal exchanger 1. The geothermal exchanger 1 can automatically cope with normal generator load fluctuations. When the generator load increases, the pressure inside the geothermal exchanger 1 decreases, so the amount of steam generated increases. When the generator load decreases, the amount of steam generated decreases because the pressure inside the geothermal exchanger 1 increases. One feature is that it has a series of automatic power generation control functions.

FIG. 2 shows details of the first heater 31.
FIG. 2A shows the installation position of the first heater 31 and its structure. FIG. 2B is a cross-sectional view taken along the line AA in FIG.
The first heater 31 supplies heat by flowing an electric current to the heater in a pressurized water superheat zone located at the bottom of a double pipe composed of the water injection pipe 2 and the steam extraction pipe 3. It can be formed by putting the outside of the inner tube into a heat-resistant electric tube and attaching the heat-resistant electric tube to the inner tube with a stainless steel band. Wiring uses heat-resistant cables to ensure permanent safety of the construction surface.

  The connection between conduits is treated so that moisture does not enter. Since the pressure water uses highly-treated pure water, the leakage current into the water is very low, but the heater does not expose the live parts to avoid the risk of increased leakage current due to impurities. And Since the outer tube is in a ground state in which the ground resistance is almost zero, only one wiring is connected, and the remaining one is connected to the outer tube. In this way, a method of connecting one end of the power transmission to the ground and connecting one end of the heater to the outer tube can be selected on the heater side. In the pressurized water overheating zone, the lower part of the outer pipe is reinforced to withstand the load of the inner pipe, and is welded and fixed to the outer pipe.

FIG. 2C shows the case where the heater is designed with a single phase, and FIG. 2D shows the case where the heater is designed with three phases.
In the case of a single phase, since one end (T phase) of the heater can be connected to the outer tube, only the R phase needs to be wired. As an example, when the single-phase 200V wiring is used, when the capacity of the heater is 10 kW, the current value is 50.0A. If the allowable current of the cable is set to a value with a margin of about 30%, the allowable current is 75A. On the other hand, when the three-phase 200V wiring is used, the current value is 28.9 A when the capacity of the heater is 10 kW. Similarly, if the allowable current of the cable is set to a value with a margin of about 30%, the allowable current is 53A.

  Thus, in the single phase, since the current value increases, the thickness of the electric wire slightly increases, but there is a merit in that only one wire for the single phase needs to be wired. In the case of three phases, the current value is 57.7% of that in the case of a single phase, and the cable can be made small. However, a cable for three phases must be wired. For this reason, designing a heater with a single phase is simpler in construction and cheaper in construction cost.

3 and 4 show a temperature decrease compensation type geothermal exchanger and a temperature decrease compensation type geothermal power generation apparatus according to the second embodiment of the present invention.
The steam take-out pipe 3 is formed so that the diameter of the steam take-out pipe 3 decreases from the lower side of the geotropical side toward the upper side of the ground surface. 3 and 4 show a structure in which the diameter of the steam extraction pipe 3 is gradually reduced from the lower side of the earth and tropical side toward the upper side of the surface of the earth.

  In FIG. 3, the diameters of the intermediate temperature region 25 and the low temperature region 26 are made smaller than the diameter of the part of the geotropical region 4 which is the high temperature region 24. An air layer 19 is formed in the water injection pipe 2 in contact with a low temperature zone close to the ground surface to improve the heat insulation effect. The high temperature region 24, the intermediate temperature region 25, and the low temperature region 26 can be set according to each situation. As an example, the low temperature region 26 is from the ground surface to a depth of 300 m, the intermediate temperature region 25 is from a depth of 300 m to 500 m, and the high temperature region 24. The depth can be 500 m to 700 m.

  Table 1 shows an example of pressure and temperature at each position shown in FIG. In the present invention, a blower and a heater are used, but as a comparison object, a comparison is made with a blower and a heater that does not use a heater. The outer pipe in Table 1 means a water injection pipe, and the inner pipe means a steam extraction pipe.

  In the case of saturated steam, the pressure at each point is determined by the steam temperature, but in the case of superheated steam, both pressure and temperature can be set arbitrarily. In Table 1, the temperature of the inner tube bottom in the case where the blower and the heater are not used is a numerical value that predicts a temperature drop during boiling under reduced pressure. Further, the temperature of the inner tube bottom in the present invention is a numerical value obtained by correcting the temperature by heating the inner tube bottom. In the pressure water zone at the bottom of the double pipe, when the temperature of the pressure water falls below the design value, the design value is corrected with a heater. Further, the pressure at the blower outlet in the present invention is a numerical value obtained by boosting with the blower.

  Table 2 shows an example of wells to be used. Considering the fact that the well temperature is 186 ° C. at a well depth of 700 m, the outer tube bottom temperature was 180 ° C. The pressure of 5.46 MPa at the bottom of the outer tube at a well depth of 700 m is a pressure obtained by pressurizing 1.6 MPa with a pressure pump. The following measured values were adopted for the depth and temperature of the well when no blower and heater were used.

  In FIG. 4, the diameter of the middle temperature region 25 is reduced and the diameter of the low temperature region 26 is further reduced with respect to the diameter of the portion of the geotropical region 4 which is the high temperature region 24. Even in this case, an air layer 19 is formed in the water injection pipe 2 in contact with the low temperature zone close to the ground surface to improve the heat insulation effect. In addition, what is shown in FIG. 3, FIG. 4 is an example, Comprising: The number of the places where a diameter reduces is not limited to what is shown here.

FIG. 5 shows a temperature decrease compensation type geothermal exchanger and a temperature decrease compensation type geothermal power generation apparatus according to the third embodiment of the present invention.
In FIG. 5, the thing of the structure where the diameter of the steam extraction pipe | tube 3 is continuously small from the geotropical side lower part toward the surface upper part is shown. FIG. 5 illustrates an example in which the rate of decrease in diameter from the high temperature region 24 to the low temperature region 26 through the intermediate temperature region 25 to the low temperature region 26 is constant and linearly decreases with a constant slope. However, the rate of decrease in diameter may not be constant, but may decrease in a curve. Furthermore, a gradual decrease in diameter and a continuous decrease may be combined.

  By forming the steam extraction pipe 3 so that the diameter of the steam extraction pipe 3 decreases from the lower side of the earth and the tropics toward the upper side of the surface of the earth, the steam single-phase flow becomes steam as it approaches the low temperature region near the surface of the earth. The speed at which the inside of the take-out pipe 3 is raised is increased and the passing time is shortened. Since the amount of heat exchanged with the water injection pipe 2 that is the outer pipe decreases in proportion to the cube of the diameter of the steam extraction pipe 3 that is the inner pipe, the steam single-phase flow passes through the low temperature region. The heat loss at the time can be reduced.

  In addition, after installing the water injection pipe 2 that is the outer pipe, when the steam extraction pipe 3 that is the inner pipe is attached, the diameter of the steam extraction pipe 3 decreases from the lower side of the geotropical side to the upper side of the ground surface. As a result, the weight of the steam extraction pipe 3 can be reduced compared to the case where the steam extraction pipe 3 is formed with the same diameter as the diameter below the geotropical side, and the convenience during construction is improved. Can do.

  Also in the embodiment shown in FIGS. 3, 4, and 5, the first heater 31 is located in the lower region of the boundary between the water injection pipe 2 and the steam extraction pipe 3 and in the region where the jet port 5 is provided. It is attached and the first heater 31 compensates for a drop in steam temperature during boiling under reduced pressure. As a result, even if there is a delay in the heat supply from the geotropics due to the difference in thermal conductivity between the pipe that generates steam and the geotropical rocks, etc., the steam temperature can be prevented from lowering and the output can be improved. To do.

A blower 32 is attached to the outlet side of the steam extraction pipe 3, and the steam taken out from the steam extraction pipe 3 is boosted by the blower 32. When the steam is boosted by the blower 32, the pressure on the suction side of the blower 32 becomes a value obtained by subtracting the blower pressure from the turbine pressure, and the pressure of the steam discharge portion at the bottom of the steam discharge pipe is lower by the blower pressure than the saturated steam pressure. To do. As a result, an effect of moving the steam from the saturated steam to the superheated steam region and a synergistic effect of assisting the vaporization of the steam are produced. Moreover, since the pressure supplied to the turbine can be set high by increasing the blower pressure, a greater effect can be obtained. Further, the power generation output can be controlled by controlling the rotational speed of the blower 32.
In addition, the position where the blower 32 is attached is not limited to the outlet side of the steam extraction pipe 3 but can be in the steam system from the steam generating unit to the turbine.

A second heater 33 is attached to the outlet side of the steam extraction pipe 3, and the steam taken out from the steam extraction pipe 3 is heated by the second heater 33. By heating the steam with the second heater 33, high-temperature and high-pressure superheated steam can be obtained. Therefore, the inlet temperature of the turbine 6 can be set high, and the output and efficiency of the turbine 6 can be improved. Moreover, since it is possible to prevent the steam from returning to water in the turbine 6, it is possible to maintain a state in which the steam that drives the turbine 6 or the heat exchanger does not easily condense.
In addition, the position where the second heater 33 is attached is not limited to the outlet side of the steam extraction pipe 3 but can be in the steam system from the steam generating unit to the turbine.
A part of the power generation output can be used as the power source of the first heater 31, the blower 32, and the second heater 33 described above. As a result, the power generation efficiency is slightly reduced, but high-temperature and high-pressure superheated steam can be produced, so that the output as a whole can be greatly improved.

  In the temperature drop compensation type geothermal exchanger according to the first to third embodiments of the present invention described above, the water supplied to the water injection pipe 2 using a natural head descends and the surrounding geotropics Since it is heated from 4, it is high-temperature pressure water in the lower part of the water injection tube 2. This high-temperature / high-pressure water is sprayed from the lower part of the water injection pipe 2 to the steam extraction pipe 3 via the jet outlet 5 in a sprayed state. Since the pressure difference between the lower part of the water injection pipe 2 and the turbine 6 is very large, it is possible to continuously produce steam at a pressure and flow rate required by the turbine 6. After the steam exits the turbine 6, it is cooled by the condenser 8, returned to the water, and sent to the water injection pipe 2 again. However, since the amount of circulating water is equal to the amount of steam required by the turbine 6, the amount of circulating water is There are very few, and a pressurization pump is not essential for the water supply to the upper part of the water injection pipe 2.

  In the present invention, the pressure gradient is formed by sending the highly treated water to the lowermost part of the water injection pipe 2 using natural pressure. The pressure at the upper part of the steam extraction pipe 3 is an inlet pressure required by the turbine 6, and the pressure loss of the inside of the steam extraction pipe 3 and the piping is an order of magnitude less than this, so theoretically the depth of the well is It is sufficient if the pressure required by the turbine 6 is sufficient, and application in a high temperature area in the earth and the tropics is possible.

  The plurality of jets 5 provided in the lower region of the steam extraction pipe 3 are formed by drilling small-diameter holes. The diameter, the number, and the flow velocity are individually determined by the power generation capacity, the temperature of the well, and the depth. Designed to. As an example, when the diameter of the water injection pipe 2 is 165.2 mm and the diameter of the steam extraction pipe 3 is 89.1 mm, it is possible to provide 100 jet nozzles 5 having a diameter of 2 mm.

  The geothermal exchanger 1 is configured by inserting an insertion pipe formed by combining at least one water injection pipe 2 and at least one steam extraction pipe 3 into a plurality of geothermal wells, and the outlet of the steam extraction pipe 3. Are connected in parallel, the steam obtained by using each geothermal well is collected in total, and the steam header 18 for equalizing the pressure of the collected steam can be provided.

  Although it is possible to use one insertion tube inserted into one geothermal well, since the temperature and pressure differ depending on the location where it is drilled, power generation for one geothermal well is used when it is used for power generation. Each output will be different. Therefore, by connecting the outlets of the steam extraction pipes 3 of the insertion pipes in parallel to a plurality of geothermal wells, and collecting the total steam obtained using each geothermal well, turbines, condensers, power generation The capacity of the machine / transformer can be designed to be large, which has the advantage of increasing the efficiency of the entire power plant. Further, by arranging the steam header 18, the pressure of the collected steam can be made uniform, and the steam whose pressure is made uniform can be supplied to a single turbine.

  For example, when three geothermal wells are used, the thermal output of each geothermal well is converted into a generator output, and when the first well is 500 kW, the second well is 400 kW, and the third well is 600 kW, three units are independent. Rather than constructing a power generation system, if these are combined and designed as one unit of well No. 1 + well 2 + well 3 = 1500 kW, the overall output will be the same, but the turbine, condenser, generator, transformer The capacity of the power plant can be designed to be large, and the efficiency of the electrical equipment is increased by the capacity. Therefore, when used for power generation, the efficiency of the entire power plant is increased. In addition, construction costs such as construction costs can be significantly reduced.

  The geothermal exchanger 1 can be a newly installed geothermal well, and is an existing facility, for example, a geothermal well attached to an existing geothermal power plant. On the other hand, an insertion pipe constituted by combining the water injection pipe 2 and the steam extraction pipe 3 can be inserted and used. Particularly, since the diameter of the insertion tube can be reduced by taking it out from the ground as a single-phase steam flow, the degree of freedom of the geothermal well that can be used is increased, and the effective use of the existing geothermal well can be promoted.

  Thus, by replacing existing wells including closed wells, the time required for environmental assessment can be greatly reduced, and development costs can be greatly reduced. In addition, the supplementary pit required for conventional geothermal power generation is unnecessary. In addition, since no geothermal fluid is used, scale corrosion is at the same level as ordinary water piping and equipment, and there is the convenience that maintenance frequency of general industrial equipment is sufficient, and concerns about the exhaustion of hot springs are eliminated. , Environmental problems are dramatically alleviated.

  In the temperature decrease compensation type geothermal exchanger of the present invention, steam is generated underground, so that a steam generator which is a pressure vessel usually installed on the ground is unnecessary. Therefore, the construction cost of the steam generator is unnecessary, and the control of the entire system can be made a simpler design. Moreover, since it is not necessary to install a steam generator, a pressure vessel handling engineer is unnecessary, and the operation cost can be reduced by reducing maintenance personnel.

  Moreover, since the pressurization pump for pumping groundwater becomes unnecessary by the temperature fall compensation type geothermal exchanger of this invention, the expense required for installation of a pressurization pump can be reduced. Furthermore, the control of the entire system can be made simpler. Furthermore, since a steam generator is unnecessary and a pressurizing pump is not essential, the site for installing ground facilities can be reduced. There are many geotropics in national parks, and it is possible to reduce the environmental burden when constructing power generation facilities.

  In the present invention, regardless of whether it is for existing power generation or hot spring use, water is supplied from the ground to the deepest part of the well on the condition that there is constant heat in the deepest part of the well. Playback can be performed. In this case, a normal pipe is sufficient as the pipe for supplying water.

FIG. 6 shows a configuration of a temperature decrease compensation type geothermal power generation apparatus in which the temperature decrease compensation type geothermal exchanger according to the first embodiment of the present invention is applied to binary power generation.
In FIG. 6, the function of the geothermal exchanger 1 is the same as that described with reference to FIG. 1, and the steam single-phase flow taken out from the steam take-out pipe 3 of the geothermal exchanger 1 is sent to the evaporator 20. Heat the low boiling point medium. The heated low-boiling point medium becomes low-boiling point vapor and moves to the turbine 6 to become power for turning the turbine 6. Power is generated by the generator 7 with this power.

  The low-boiling-point medium vapor that has exited the turbine 6 is then cooled by cooling water in the condenser 21 to return to the low-boiling-point medium, and is sent to the evaporator 20 by the pump 34. By repeating this, power is continuously generated. If necessary, the makeup water 11 is replenished from the makeup water tank 12 via the water treatment device 10. The makeup water level is adjusted by a makeup water control valve 13. A steam header 18 and a steam control valve 15 are provided between the steam take-out pipe 3 and the turbine 6.

FIG. 7 shows a configuration of a temperature decrease compensation type geothermal power generation apparatus in which the temperature decrease compensation type geothermal exchanger according to the second embodiment of the present invention is applied to binary power generation.
In FIG. 7, the function of the geothermal exchanger 1 is the same as that described based on FIG.
FIG. 7 shows the one using the geothermal exchanger 1 of the embodiment shown in FIG. 4, but binary using the one shown in FIG. 3 or the geothermal exchanger 1 of the embodiment shown in FIG. 5. It can also generate electricity.

Below, embodiment which pressurizes on the ground with respect to the water supplied to a water injection pipe is described.
FIG. 8 shows a temperature decrease compensation type geothermal exchanger and a temperature decrease compensation type geothermal power generation apparatus according to this embodiment.

  In FIG. 8, the geothermal exchanger 1 includes a water injection pipe 2 provided in the ground and supplied with water from the ground, and a steam extraction pipe 3 provided in the ground so as to be in contact with the water injection pipe 2. ing. In FIG. 8, the water injection pipe 2 has an outer pipe close to the geotrophic 4 side, and the steam extraction pipe 3 has a double pipe structure with an inner pipe provided inside the water injection pipe 2, but conversely, The steam extraction pipe 3 may be an outer pipe and the water injection pipe 2 may be an inner pipe.

  The steam outlet pipe 3 is provided with a plurality of jet outlets 5 in the lower region thereof, and the water injection pipe 2 and the steam outlet pipe 3 are opened by the jet outlet 5. That is, the jet nozzle 5 is provided at the boundary between the water injection pipe 2 and the steam extraction pipe 3. The steam extraction pipe 3 is connected to the turbine 6, and the pressure in the steam extraction pipe 3 is reduced to a pressure lower than that required by the turbine 6.

  A pressurizing pump 27 for pressurizing the water supplied to the water injection pipe 2 is disposed on the ground. Since the water supplied to the water injection pipe 2 is pressurized by the pressurizing pump 27 on the ground, in the lower part of the water injection pipe 2, the pressure by this pressurization is almost proportional to the depth from the ground. Pressurized water with the total pressure added.

  Heat is supplied from the earth tropics 4 to the pressurized water to become high-temperature pressure water. Since the inside of the steam extraction pipe 3 is depressurized, using this pressure difference, as shown by the arrow, high-temperature pressure water is sprayed from the jet outlet 5 into the steam extraction pipe 3 in the spray state, and the turbine 6 is required. It is vaporized using the pressure difference between the pressure of the water and the bottom of the water injection pipe 2 and converted into a single-phase steam flow. The steam single-phase flow generated in the underground moves to the turbine 6 due to a pressure difference between the steam take-out pipe 3 and the turbine 6, and then expands in the turbine 6 to become power for turning the turbine 6. Power is generated by the generator 7 with this power.

  Also in this embodiment, the 1st heater 31, the blower 32, and the 2nd heater 33 can be attached. In addition, as shown in FIGS. 3, 4, and 5, the steam take-out pipe 3 is formed so that the diameter of the steam take-out pipe 3 becomes smaller from the geotropical side lower side toward the ground surface side upper side. A pressurizing pump 27 can also be installed.

  Thereafter, the steam exiting the turbine 6 is cooled by the cooling water 9 in the condenser 8 and returned to the water, and is supplied again to the water injection pipe 2. Since the amount of water to be circulated is equal to the amount of steam required by the turbine 6, the amount of water to be circulated is very small. By repeating this process, geothermal heat is continuously extracted. If necessary, the makeup water 11 is replenished from the makeup water tank 12 via the water treatment device 10. The water level of the makeup water 11 is adjusted by the makeup water adjustment valve 13. A steam control valve 15 is provided between the steam take-out pipe 3 and the turbine 6. In addition, a pressure control valve 17 is provided.

  As described above, in the present invention, the high-pressure hot water causes the jet outlet to be discharged by the first heater attached to the lower boundary region between the water injection pipe and the steam discharge pipe and provided with the jet outlet. When converted to a vapor single-phase flow, the main feature is that it compensates for the temperature drop during boiling under reduced pressure. This makes it possible to reduce the size and increase the efficiency of turbines by increasing the steam pressure and temperature and using superheated steam. In addition, geothermal power generation is possible even in relatively low temperatures at shallow depths, which are overwhelmingly distributed. This has a great advantage, and greatly contributes to the spread of geothermal power generation.

  The present invention prevents a drop in steam temperature when boiling by decompression to obtain steam, eliminates the adverse effects of steam liquefaction, and lowers the temperature at which high power generation is possible even at a relatively low temperature range at a shallow depth. It can be widely used as a compensation type geothermal exchanger and a temperature decrease compensation type geothermal power generation device. In particular, it has a significant advantage in that it can effectively use existing wells and reduce the environmental burden when constructing power generation facilities. Japan has relied heavily on nuclear power due to accidents at nuclear power plants. Considering the current situation in which energy policies have to be reviewed from the ground up, geothermal power generation will be possible even at relatively low temperatures at shallow depths, which are overwhelmingly distributed, and thus will play a role as a future base power generation Can greatly contribute to industrial use.

DESCRIPTION OF SYMBOLS 1 Geothermal exchanger 2 Water injection pipe 3 Steam extraction pipe 4 Geotropics 5 Spout 6 Turbine 7 Generator 8 Condenser 9 Cooling water 10 Water treatment device 11 Supply water 12 Supply water tank 13 Supply water control valve 15 Steam control valve 16 Emergency pressure reducing valve 17 Pressure control valve 18 Steam header 19 Air layer 20 Evaporator 21 Condenser 24 High temperature region 25 Medium temperature region 26 Low temperature region 27 Pressure pump 31 First heater 32 Blower 33 Second heater 34 Pump

Claims (13)

  A water injection pipe provided in the ground and supplied with water from the ground; a steam extraction pipe provided in the ground so as to be in contact with the water injection pipe and having a plurality of jets; the water injection pipe and the steam extraction A first heater attached to a region below the boundary with the pipe and provided with the jet port, and the pressure in the steam extraction pipe is reduced to a pressure lower than that required by the turbine. The high-pressure hot water generated by supplying heat from the earth to the water in the water injection pipe is converted into a steam single-phase flow in the steam take-out pipe through the jet port, and the first heater A temperature decrease compensation type geothermal exchanger, wherein the temperature decrease during boiling under reduced pressure is compensated and taken out to the ground.   The blower is attached to the outlet side of the steam extraction pipe or in a steam system extending from the steam generation section to the turbine, and the steam taken out from the steam extraction pipe is boosted by the blower. Temperature drop compensation type geothermal exchanger.   The temperature decrease compensating geothermal exchanger according to claim 2, wherein the power generation output is controlled by controlling the rotational speed of the blower.   A second heater is attached to the outlet side of the steam extraction pipe or in the steam system from the steam generation section to the turbine, and the steam taken out from the steam extraction pipe is heated by the second heater. The temperature fall compensation type geothermal exchanger according to any one of claims 1 to 3.   The steam take-out pipe is disposed inside the water injection pipe, and the steam take-out pipe is formed so that the diameter of the steam take-out pipe is reduced from the lower side of the tropical zone toward the upper side of the ground surface. The temperature fall compensation type geothermal exchanger according to any one of claims 1 to 4.   The temperature drop compensation type geothermal exchanger according to claim 5, wherein the diameter of the steam extraction pipe is gradually reduced from the lower side of the geotropical side toward the upper side of the surface of the earth.   The temperature drop compensation type geothermal exchanger according to claim 5, wherein the diameter of the steam extraction pipe is continuously reduced from the lower side of the geotropical side toward the upper side of the ground surface.   By lowering the level of water supplied to the water injection pipe, a heat insulating part is formed by forming an air layer above the water injection pipe with respect to a region in contact with a low temperature zone close to the ground surface. The temperature fall compensation type geothermal exchanger according to any one of claims 1 to 7, wherein   The temperature decrease compensating geothermal exchanger according to any one of claims 1 to 8, wherein a pressurizing pump for pressurizing water supplied to the water injection pipe is disposed on the ground.   An insertion pipe formed by combining at least one water injection pipe and at least one steam extraction pipe is inserted into a plurality of geothermal wells, and outlets of the steam extraction pipes are connected in parallel. The steam obtained by using each geothermal well is collected in total, and a steam header that equalizes the pressure of the collected steam is provided. Low temperature compensation type geothermal exchanger.   The temperature decrease compensating geothermal exchanger according to claim 10, wherein the geothermal well is attached to an existing facility.   A temperature decrease compensation type geothermal power generation apparatus that performs power generation using the temperature decrease compensation type geothermal exchanger according to any one of claims 1 to 11.   The temperature decrease compensation type geothermal power generation apparatus according to claim 12, wherein the power generation is based on a binary system.

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