Supercritical co2 circulating laser drilling device and power generation system
Patent Information
- Application Number
- JP2023141063
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-08-31
- Publication Date
- 2025-03-13
Smart Images
Figure 2025034585000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a high-power laser drilling device and power generation system that uses supercritical CO2 circulation. [Background technology]
[0002] As described in the following Patent Document 1, a laser drilling technique is known that uses a laser to melt and break rocks to excavate the earth. The technique described in Patent Document 1 involves rotating a laser beam source to evenly irradiate the bottom of a borehole with a laser beam, while removing rock material at the bottom of the borehole using a mechanical assembly such as a roller. The technique of Patent Document 1 also makes it possible to remove drilling debris by releasing a fluid toward the bottom of the borehole and raising it up. However, the technique of Patent Document 1 requires a mechanical assembly to remove rock material, and also lists general drilling mud, water, halogenated carbon, nitrogen, oil, etc. as fluids for removing drilling debris (paragraph
[0078] ). However, these fluids have limitations in their ability to remove drilling debris.
[0003] In addition, as a drilling means other than the laser beam, a drilling technology using supercritical CO2 has also been developed, as described in Patent Document 2. The technology described in Patent Document 2 performs drilling by injecting supercritical CO2 in several directions. However, the technology in Patent Document 2 has the problem that the supercritical CO2 injection flow does not hit the rock to be drilled evenly, and the problem that it does not have a means for removing the fragments crushed by the injection of supercritical CO2. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Patent No. 5,844,868 [Patent Document 2] U.S. Patent No. 6,347,675 Summary of the Invention [Problem to be solved by the invention]
[0005] The present invention has been made in consideration of the above facts, and aims to provide a laser drilling device that has an extremely simple configuration and can remarkably improve the drilling rate, cooling efficiency, and drilling depth compared to conventional drilling techniques, while more efficiently removing debris produced by drilling.
[0006] Another object of the present invention is to realize a power generation system that significantly improves power generation efficiency by heating and circulating supercritical CO2 using geothermal heat obtained from deep underground excavated by the above-mentioned laser drilling device, i.e., a next-generation highly efficient geothermal power generation system. [Means for solving the problem]
[0007] In order to solve the above problems, the supercritical CO2 circulation type laser drilling device of the present invention comprises a laser inner tube that defines a laser optical path through which a laser beam passes, a first casing that covers the outer periphery of the laser inner tube and defines a CO2 supply path between the laser inner tube and the first casing, a rotating tip portion that is rotatably attached to the tip of at least one of the laser inner tube and the first casing around the axial direction, and a second casing that covers the outer periphery of the first casing and defines a return flow path for crushed material between the first casing and the second casing. The rotating tip portion rotates by CO2 supplied through the CO2 supply path, and has a laser opening from which the laser beam propagated through the laser optical path is emitted and a supercritical CO2 port from which the supplied CO2 is injected in a supercritical state.
[0008] The rotating tip includes, for example, blades that obtain a rotational moment for rotating the rotating tip from the flow of CO2 supplied from the CO2 supply passage. Preferably, the rotary tip has a plurality of the supercritical CO2 ports, the laser aperture is located at the center of the rotary tip, and the plurality of the supercritical CO2 ports are located around the laser aperture. For example, the rotary tip is formed in a truncated cone shape, the plurality of the supercritical CO2 ports are formed on the side of the truncated cone, and the laser aperture is formed on the apex of the truncated cone. Also preferably, the inlet pressure of the supercritical CO2 supplied to the CO2 supply path is equal to or higher than the critical pressure of CO2.
[0009] The laser beam incident on the laser optical path has its beam width adjusted at the focusing point where it leaves the laser aperture by a combination of a plurality of beam collimators.
[0010] The power generation system according to the first aspect of the present invention, which generates power by heating supercritical CO2 using geothermal energy, comprises a heat transfer double tube that is embedded in a borehole drilled by the laser drilling device according to each of the above aspects and through which supercritical CO2 is circulated, and at least one power generation device that generates power by rotating a gas turbine using the supercritical CO2 heated by geothermal energy as it circulates through the heat transfer double tube and rotating a generator connected to the gas turbine, wherein the heat transfer double tube comprises an outer tube having a closed tip and arranged with the closed tip facing downward, and an inner tube having an open tip and arranged inside the outer tube with the open tip facing downward, and a CO2 supply path is defined between the inner tube and the outer tube, and an internal passage of the inner tube from the open tip of the inner tube defines a return path for the heated supercritical CO2.
[0011] A power generation system according to a first aspect, which is more preferable in terms of improving power generation efficiency, includes N (N>1) power generation devices from a first power generation device to an Nth power generation device, the first power generation device generates power by rotating a gas turbine using supercritical CO heated by the heat transfer double pipe, and the kth power generation device (1 <The N power generation devices are connected in a cascade manner such that supercritical CO2 used for power generation in the k-th power generation device (k < N) is used for power generation in the (k + 1)-th power generation device.
[0012] Preferably, at least a part of the supercritical CO2 used for power generation in the N-th power generation device is returned to the CO2 supply path of the heat transfer double tube to form a supercritical CO2 circulation system.
[0013] The power generation system according to the first aspect of the present invention, which generates power by heating supercritical CO2 with a heat source, includes N (N > 1) power generation devices from the first power generation device to the N-th power generation device that rotate a gas turbine using the heated supercritical CO2 and rotate a generator connected to the gas turbine to generate power. The first power generation device generates power by rotating a gas turbine using supercritical CO2 heated by the heat source, and the N power generation devices are connected in a cascade manner such that supercritical CO2 used for power generation in the k-th power generation device (1 < k < N) is used for power generation in the (k + 1)-th power generation device, and the heat source is a deep underground geothermal source drilled by the laser drilling device according to each of the above aspects.
[0014] The power generation system according to the second aspect of the present invention, which generates power by circulating a heat transfer medium heated by a heat source to heat supercritical CO2, includes N (N > 1) power generation devices from the first power generation device to the N-th power generation device that rotate a gas turbine using the heated supercritical CO2 and rotate a generator connected to the gas turbine to generate power, and N (N > 1) heat exchange devices from the first heat exchange device to the N-th heat exchange device that perform heat exchange between the heat transfer medium and supercritical CO2. The first heat exchanger performs heat exchange between the heat transfer medium heated by the heat source and the supercritical CO2 circulating for power generation in the first power generation device, and the (k + 1)-th heat exchanger (1 <When k < N, the N power generation devices and the N heat exchangers are connected in a cascade manner so as to perform heat exchange between the heat transfer medium heat-exchanged in the k-th heat exchanger and the supercritical CO2 circulated for power generation of the (k + 1)-th power generation device. The heat source is a deep underground geothermal source drilled by the laser drilling device according to each of the above aspects.
[0015] Preferably, at least a part of the heat transfer medium heat-exchanged in the N-th heat exchanger is heated by the heat source and circulated back to the first heat exchanger. Preferably, each of the N heat exchangers includes a container in which an internal space for holding a heat transfer medium is formed, and a heat exchange pipe through which supercritical CO2 flows and which is disposed in the internal space. The container has a medium inlet for allowing a higher-temperature heat transfer medium to flow into the internal space and a medium outlet for allowing the heat transfer medium that has become lower-temperature for heat exchange to flow out of the internal space. The medium inlet and the medium outlet are provided at positions from one end of the container. The container further has a partition for partially partitioning the internal space into at least two regions, i.e., a high-temperature region on the medium inlet side and a low-temperature region on the medium outlet side. The partition leaves a gap from the end portion opposite to the one end portion, and the two regions communicate with each other through the gap. The heat exchange pipe has a supercritical CO2 inlet into which supercritical CO2 is introduced and a supercritical CO2 outlet from which supercritical CO2 flows out. The heat exchange pipe is divided into a first section from the supercritical CO2 inlet and a second section from the supercritical CO2 outlet. The first section of the heat exchange pipe is disposed in the low-temperature region, and the second section of the heat exchange pipe is disposed in the high-temperature region.
[0016] The heat transfer medium is, for example, a liquid metal selected from Al, Ca, Na, or a molten salt. The power generation systems according to the first and second aspects of the present invention can be expanded to aspects that use not only geothermal sources deep underground excavated by the laser drilling device according to each of the above aspects, but also other heat sources (e.g., geothermal sources deep underground excavated by other drilling devices, nuclear fusion reactors (divertors, blankets, etc.), nuclear reactors, solar light, hydrogen-based thermal reactors, high-level waste, biomass). [Brief description of the drawings]
[0017] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a drilling device according to one embodiment of the present invention, in which FIG. 1(A) is an oblique view of the drilling device, FIG. 1(B) is an oblique view of a central shaft of the drilling device shown in FIG. 1(A), and FIG. 1(C) is a view from the axial direction of the central shaft shown in FIG. 1(B). [Diagram 2] FIG. 2 is a side cross-sectional view of a central shaft of a drilling rig according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a perspective view showing a state in which the excavation device according to one embodiment of the present invention is embedded in the ground and excavating. [Figure 4] FIG. 4 is a diagram for explaining a state in which supercritical CO2 and a laser beam are supplied to the drilling device according to one embodiment of the present invention to drill underground. [Diagram 5] FIG. 5 is a graph showing the relationship between the particle size (mm) of rock particles broken up by melting underground rock with a laser beam and cooling with sprayed supercritical CO2, and the distance (m) blown up by supercritical CO2, for each pressure (25 MPa to 150 MPa) of supplied supercritical CO2, using an excavation device according to one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing an example of a system configuration when excavating deep underground using an excavation device according to one embodiment of the present invention. [Figure 7] FIG. 7 is an illustration of a laser beam source for use in the drilling system of FIG. 6 using a drilling rig according to an embodiment of the present invention. [Figure 8]FIG. 8 is a schematic diagram of a heat transfer double tube for heating supercritical CO2 with a geothermal source. [Figure 9] FIG. 9 is a schematic diagram of a cascade-type power generation system according to one embodiment of the present invention, which uses the heat transfer double pipe of FIG. 8 to generate power using supercritical CO2 heated by heat from a geothermal source. [Figure 10] FIG. 10 is a schematic diagram of a cascaded power generation system according to another embodiment of the present invention, which generates power using supercritical CO2 heated using a heat exchanger through which a heat transport medium heated by an arbitrary heat source is transported. [Figure 11] FIG. 11 is a diagram showing specific physical quantities (temperature, pressure, flow rate, power) and energy efficiency (%) of supercritical CO2 and heat transport medium (liquid metal) in one configuration example of each power generation device and its heat exchanger provided in the cascade power generation system of FIG. 10. [Figure 12] FIG. 12 is a schematic diagram of a heat exchanger for each power generation device, in which FIG. 12(A) is an oblique view of the heat exchanger, FIG. 12(B) is a cross-sectional view of the heat transport medium container of the heat exchanger, FIG. 12(C) is an oblique view of the supercritical CO2 piping of the heat exchanger, and FIG. 12(A) is a cross-sectional side view of the heat exchanger. [Figure 13] FIG. 13 is a diagram for explaining a thermal energy redistribution method of the heat exchanger shown in FIG. [Figure 14] FIG. 14 is a schematic diagram showing an example of the configuration of each power generation device provided in the cascade type power generation system of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] (Laser drilling equipment) Hereinafter, a laser drilling device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1(A) shows a supercritical CO2 circulation type laser drilling device 1 according to one embodiment of the present invention. As shown in the figure, the laser drilling device 1 includes a central shaft 2 for transmitting a laser beam and supercritical CO2. As shown in FIG. 1(B), the central shaft 2 includes a first casing 6 and a rotary tip 3, the details of which will be described later. As also shown in FIG. 1(C), the rotary tip 3 includes a laser aperture 4 disposed at the center of the rotary tip 3 from which the laser beam is emitted, and a plurality of supercritical CO2 ports 5 formed around the laser aperture 4 from which supercritical CO2 is injected. In addition, the rotary tip 3 is formed in the shape of a truncated cone, the plurality of supercritical CO2 ports 5 are formed on the side of the truncated cone, and the laser aperture 4 is formed at the apex of the truncated cone.
[0019] Returning to Figure 1(A), a second casing 7 further covers the side of the central shaft 2, i.e., the outer periphery of the first casing 6, and a return flow path 8 for the crushed material, described later, is defined between the first casing 6 and the second casing 7.
[0020] FIG. 2 shows a cross-sectional view of the central shaft 2. As shown in the figure, the central shaft 2 includes a laser inner tube 9 that defines a laser optical path 10 through which the laser beam passes, and the first casing 6 that covers the outer periphery of the laser inner tube 9, and a CO2 supply path 11 is defined between the laser inner tube 9 and the first casing 6. A laser beam supply port 13 is formed at the ground side end of the laser inner tube 9, and a CO2 supply port 14 is formed at the ground side end of the CO2 supply path 11. The laser beam may be directly emitted to the laser beam supply port 13, or an optical fiber cable (not shown) that transmits the laser beam may be connected to the laser beam supply port 13. A pipe (not shown) that supplies CO2 may be connected to the CO2 supply port 14. The pressure of CO2 supplied at the CO2 supply port 14 is preferably equal to or higher than the critical pressure (7.38 MPa).
[0021] Furthermore, the rotary tip 3 is attached to the tip of at least one of the laser inner tube 9 and the first casing 6 facing underground so as to be rotatable around the axial direction. In this state, the laser opening 4 of the rotary tip 3 communicates with the laser inner tube 9, and the CO2 supply path 11 communicates with the supercritical CO2 port 5. Therefore, when a laser beam is supplied to the laser supply port 13, the laser beam passes through the laser optical path 10 and is irradiated from the laser opening 4, and the supercritical CO2 supplied from the CO2 supply port 14 passes through the CO2 supply path 11 and is sprayed from the supercritical CO2 port 5.
[0022] Furthermore, the rotating tip 3 is provided with a blade 12 at a position where it hits the flow of supercritical CO2 supplied from the CO2 supply passage 11, and the blade 12 is configured to obtain a rotational moment from the flow of supercritical CO2 for rotating the rotating tip 3. For example, the blade 12 may be formed in a screw shape, but the present invention is not limited to this example.
[0023] The rotation mechanism for rotatably supporting the rotating tip 3 includes a rotation protrusion 3a provided at the base end of the rotating tip 3 and a rotation groove 6a formed on the inner wall of the first casing 6. The rotation protrusion 3a slides in the rotation groove 6a while fitted into the rotation groove, thereby enabling the rotating tip 3 to rotate around the central axis of the laser drilling device 1. The rotation mechanism for the rotating tip is not limited to the example shown in FIG. 2, and other configurations using bearings or the like are also possible. The rotating tip 3 can also be rotatably attached to the laser inner tube 9 in a similar configuration.
[0024] When the rotating tip portion 3 rotates, the multiple supercritical CO2 ports 5 also rotate in the circumferential direction, so that the flow of supercritical CO2 injected from the supercritical CO2 ports 5 via the CO2 supply passage 11 also rotates in the axial direction.
[0025] FIG. 3 shows a schematic diagram of a laser drilling device 1 that drills deep underground to a geothermal source 15a. Even if the borehole 17 drilled by the laser drilling device 1 is deep underground, a crushed material recovery port 16 is formed at the ground end of the crushed material return flow path 8, and it can be understood that a mixture of crushed material and CO2 can be recovered from the crushed material recovery port 16. Here, the deep underground is a deep part that can use geothermal energy as a suitable heat source for a power generation system described later, for example, an underground part at a depth of 5 km to 8 km, or 8 km or more. The present invention is not limited to this example of underground depth.
[0026] Next, the operation of the laser drilling device 1 will be described with reference to FIGS. As shown in FIG. 4, with the tip of the laser drilling device 1 facing the ground, a laser beam is supplied through the laser optical path 10 of the laser inner tube 9, and supercritical CO2 at a constant pressure is supplied through the CO2 supply path 11. Thus, a laser beam is emitted from the laser aperture 4 and irradiated to the rock in the ground. The rock is heated to a high temperature by the laser beam, melted, and SiO2 and other rock components are precipitated. When the supercritical CO2 flow is injected into this high-temperature melt 18 containing SiO2 precipitates, the melt 18 containing SiO2 precipitates is rapidly cooled by the rapid adiabatic expansion of the supercritical CO2 heated to a high temperature, along with the crushing by the high-pressure, high-speed flow, and thermal stress fracture occurs, and the melt 18 is crushed into fine particles 19 (φ2 to 40 mm). The high-pressure, high-speed flow of supercritical CO2 is reversed when it hits the ground and rises through the return flow path 8. At this time, the crushed particles are also blown up together with the supercritical CO2 flow and rise through the return flow path 8.
[0027] The flow injected from the supercritical CO2 port 5 onto the melt and precipitate 18 is evenly sprayed onto the melt and precipitate 18 because the rotary tip 3 is rotating, so that the melt and precipitate are evenly crushed and transported through the return flow path 8 against gravity G, and can be collected on the ground. According to this embodiment, rock fracture is performed by combining rock melting by a laser beam, injection of supercritical CO2, and the cooling effect due to the rapid adiabatic expansion of supercritical CO2, and the generated crushed material is returned to the ground by the upward flow of supercritical CO2, so that it is possible to significantly improve the excavation depth and excavation rate. The laser drilling device 1 according to one embodiment of the present invention can be said to be a supercritical CO2 circulation type laser drilling device in the sense that it supplies supercritical CO2 underground, uses it for rock fracture, and then returns the crushed material to the ground. The supercritical CO2 circulation type laser drilling apparatus of the present invention includes an embodiment in which supercritical CO2 returned to the ground (or near the ground) is reused as described below, but is not limited to the embodiment in which returned supercritical CO2 is reused.
[0028] FIG. 5 shows the relationship between the particle size d (mm) of the crushed particles 19 and the blow-up distance (m) of the crushed particles, which was obtained using an analytical model, for each pressure (25 MPa to 150 MPa) of the supplied supercritical CO2. According to FIG. 5, when supercritical CO2 is supplied at a pressure of 120 MPa or more, crushed particles with a particle size of 10 mm or less are blown up as far as 8 km or more. Therefore, in this embodiment, it is considered that the transportation performance for removing the crushed material from the ground is remarkably excellent even in deep excavation. This is due to the effect of the significantly improved crushing performance and transportation performance caused by supercritical CO2, which is denser than normal gas.
[0029] FIG. 6 shows an example of a configuration of a drilling system using a laser drilling device 1 according to one embodiment of the present invention. As shown in the figure, the drilling system 1A includes a support structure 20 that supports the laser drilling device 1 according to this embodiment so as to be movable according to the drilling depth, a laser beam source 21 that supplies a laser beam to the laser drilling device 1, a supercritical CO2 generation source 22 that generates supercritical CO2 by raising CO2 to a critical temperature or higher and a critical pressure or higher and supplies it to the laser drilling device 1, a CO2 capture unit 23 that separates carbon dioxide and crushed material from a mixture of carbon dioxide and crushed material recovered from the crushed material recovery port 16 (FIG. 3) of the laser drilling device 1, and a CE tank 24 that stores the CO2 separated by the CO2 capture unit 23. The CO2 stored in the CE tank 24 is sent to the supercritical CO2 generation source 22, supercriticalized, and supplied to the laser drilling device 1 again for reuse.
[0030] 7 shows a schematic diagram of the laser beam source 21. The laser beam source 21 as an example includes a plurality of beam collimators 25. The combination of the plurality of beam collimators 25 makes it possible to adjust the beam width at the focusing point at the laser aperture. At this time, the laser beams emitted from each of the plurality of beam collimators 25 are non-coherently combined and focused. Of course, the laser beam of the laser beam source of the present invention is not limited to this example, and also includes the case where a plurality of laser beams are coherently combined and focused.
[0031] The laser beam source 21 is selected to be capable of outputting a high-power laser beam capable of melting the rock mass at the target excavation depth deep underground. (Double heat transfer tube) As an invention that utilizes a borehole drilled by a laser drilling device 1 according to one embodiment of the present invention, a heat transfer double pipe that transfers geothermal heat to a heat transport medium (for example, supercritical CO2) can be considered.
[0032] FIG. 8 shows one example of the configuration of such a heat transfer double pipe 30. As shown in the figure, the heat transfer double pipe 30 is embedded in a borehole 17 drilled by a laser drilling device 1. The heat transfer double pipe 30 includes an outer pipe 31 having a closed tip and arranged with the closed tip facing downward, and an inner pipe 32 having an open tip and arranged inside the outer pipe 31 with the open tip facing downward. A supercritical CO2 supply path is defined between the inner pipe 32 and the outer pipe 31. The internal passage of the inner pipe 32 from the open tip of the inner pipe 32 defines a return path for the heated supercritical CO2. Therefore, when supercritical CO2 is supplied from the ground side end of the outer pipe 31, the supercritical CO2 flows downward through the supercritical CO2 supply path defined between the inner pipe 32 and the outer pipe 31, and is heated by the geothermal source 15a deep underground. The heated supercritical CO2 rises due to the supply pressure from the closed end of the outer tube 31 through the supercritical CO2 return path of the inner tube 32 and is collected from the ground end of the inner tube 32. (Power generation system (first modified example)) A possible application of the supercritical CO2 heated by the heat transfer tube 30 is a power generation system including at least one power generation device that uses the supercritical CO2 to rotate a gas turbine, which in turn rotates a generator connected to the gas turbine to generate electricity. Figure 9 shows an example of the configuration of such a power generation system 100.
[0033] As shown in Fig. 9, the power generation system 100 includes a first power generation device 50a that uses supercritical CO2 (SCO2) heated to a high temperature (e.g., 800 degrees) by geothermal heat through a heat transfer double pipe 30 to rotate a gas turbine and generate power by rotating a generator 65a connected to the gas turbine, a second power generation device 50b that uses supercritical CO2 used for the power generation of the first power generation device 50a to rotate a gas turbine and generate power by rotating a generator 65b connected to the gas turbine, and a third power generation device 50c that uses supercritical CO2 used for the power generation of the second power generation device 50b to rotate a gas turbine and generate power by rotating a generator 65c connected to the gas turbine. That is, the power generation system 100 includes three power generation devices 50a to 50c connected in a cascade. This cascade connection makes it possible to significantly increase the overall cycle thermal efficiency compared to when there is only one power generation device.
[0034] Even if the supercritical CO2 (SCO2) is at a high temperature (e.g., 800°C) when it is supplied to the first power generation device 50a, it will perform the work of generating electricity in sequence from the power generation devices 50a to 50c, so that the temperature of the supercritical CO2 (SCO2) will drop to a lower temperature (e.g., 450°C) when it is discharged from the last, third power generation device 50c. Therefore, at least a part of the supercritical CO2 (SCO2) used and discharged in the third power generation device 50c can be reheated again by geothermal energy by returning it to the supercritical CO2 supply path of the heat transfer double pipe 30. This makes it possible to form a circulation system of supercritical CO2 in which thermal energy is constantly replenished by geothermal energy. It is also possible to use the remaining part of the supercritical CO2 (SCO2) used and discharged in the third power generation device 50c for other purposes, such as district heating.
[0035] The power generation system 1A shown in FIG. 9 connected three power generation devices in a cascade manner. However, the present invention is not limited to this example, and it is also possible to connect two power generation devices or four or more power generation devices. The power generation system 100 in which the number of a plurality of power generation devices is generalized includes N (N>1) power generation devices from the first power generation device to the Nth power generation device. The first power generation device generates power by rotating a gas turbine using supercritical CO2 heated by the heat transfer double pipe, and the supercritical CO2 used for power generation by the kth power generation device (1 < k<N) is used for power generation by the k+1th power generation device, and the N power generation devices are connected in a cascade manner.
[0036] Note that the heat source 15a shown in FIG. 9 was a geothermal source, but it is also possible to use at least any one of other heat sources, such as a fusion reactor (divertor, blanket, etc.), a nuclear reactor, sunlight, a hydrogen-based thermal power plant, high-level radioactive waste, biomass, etc. The power generation systems 101 and 101A using a geothermal source as the heat source 15 also include an aspect in which a heat transfer double pipe 30 embedded in the excavation hole 17 excavated by the laser excavation device 1 of the present invention is provided (there may also be other aspects using a geothermal source). By this aspect, an example of a configuration of a next-generation high-efficiency geothermal power generation system is realized. (Power Generation System (Second Modification Example)) In a power generation system using supercritical CO2, as shown in FIG. 9, it is conceivable to directly heat supercritical CO2 by a heat source, but a power generation system is also conceivable in which a heat transfer medium is heated by a heat source and heat exchange is performed between the heated heat transfer medium and supercritical CO2. FIG. 10 shows an example of such a power generation system 101. For the same constituent elements as those in FIG. 9, the same reference numerals are attached and detailed description is omitted.
[0037] As shown in FIG. 10, the power generation system 101 includes three power generation devices 50a, 50b, and 50c, and three corresponding heat exchangers 33a, 33b, and 33c. The heat exchanger 33a exchanges heat between the heat transport medium heated by the heat source 15 and the supercritical CO2 circulating for the power generation of the power generation device 50a, the heat exchanger 33b exchanges heat between the heat transport medium heat exchanged in the heat exchanger 33a and the supercritical CO2 circulating for the power generation of the power generation device 50b, and the heat exchanger 33c exchanges heat between the heat transport medium heat exchanged in the heat exchanger 33b and the supercritical CO2 circulating for the power generation of the power generation device 50c. At least a part of the heat transport medium heat exchanged in the heat exchanger 33c is reheated by the heat source 15 and circulated back to the heat exchanger 33a. That is, in the power generation system 101, the three power generation devices and the three heat exchangers are connected in a cascade manner. Also, another type of power generation device 34 that generates power using the heat transport medium discharged from the heat exchanger 33c (for example, a power generation device that rotates a gas turbine using the heat transport medium, or heats water using the heat transport medium to generate steam and rotate a steam turbine) may be provided. In this case, the heat transport medium discharged from the other type of power generation device 34 is reheated by the heat source 15 and circulated back to the heat exchanger 33a.
[0038] As the heat transport medium, for example, liquid metals (LM) such as Al (melting point 660°C, boiling point 2520°C), Ca (melting point 842°C, boiling point 1503°C), and Na (melting point 97.81°C, boiling point 883°C) and molten salts can be used. Therefore, by appropriately selecting the heat transport medium, as described later, the power generation devices 50a, 50b, and 50c using supercritical CO2 can achieve an operating temperature range of 500°C to 800°C, and the power generation efficiency of the entire power generation system can be achieved to about 90%. As for other types of power generation devices 34, even if the temperature of the heat transport medium is lowered to 500°C, a power generation efficiency of about 20% can be achieved.
[0039] Fig. 11 shows the analysis result of a 26MW-class power generation system 101A designed based on the power generation system 101 of Fig. 10. In the power generation system 101A, liquid metal (LM) as a heat transport medium is heated to 1073K and supplied to the heat exchanger 33a at a flow rate of 480.5kg / s and a pressure of 0.206MPa. The heat exchanger 33a exchanges heat with supercritical CO2 (temperature 798K, flow rate 99.49kg / s, 26.0MPa) discharged from the power generation device 50a, heats the supercritical CO2 to a temperature of 1004.6K (pressure 25.0MPa) and sends it back to the power generation device 50a. This enables the power generation device 50a to generate 13.47MW of electricity. The heat exchanger 33a sends the heat transport medium (temperature 1004.5K, pressure 0.20MPa) whose temperature has been slightly lowered by the heat exchange to the heat exchanger 33b, and a similar heat exchange is performed between the heat exchanger 33b and the power generation device 50b with the parameter values shown in the figure, and the power generation device 50b generates 6.2MW of electricity. The heat exchanger 33b sends the heat transport medium that has been heat exchanged with the supercritical CO2 of the power generation device 50b to the heat exchanger 33c, and a similar heat exchange is performed between the heat exchanger 33c and the power generation device 50c with the parameter values shown in the figure, and the power generation device 50b generates 3.0MW of electricity. Finally, the heat transport medium (temperature 879.49K, 0.18MPa) that has been heat exchanged with the supercritical CO2 of the power generation device 50c is discharged from the heat exchanger 33c and returned to the heat source 15. Analysis based on the above parameters shows that the heat exchanger 33a has a heat cycle efficiency of 51.8% (equivalent to 13.5 MW), the heat exchanger 33b has a heat cycle efficiency of 49.5% (equivalent to 6.12 MW), and the heat exchanger 33c has a heat cycle efficiency of 47.13% (equivalent to 2.99 MW), making it possible to achieve a total heat cycle efficiency of 86.96%. In this way, by cascading multiple heat exchangers and power generation devices, a heat cycle efficiency of approximately 90%, i.e., a power generation efficiency, can be achieved that cannot be achieved with a single device.
[0040] The power generation systems 101 and 101A shown in FIGS. 10 and 11 connected three power generation devices in a cascade manner. However, the present invention is not limited to this example, and it is also possible to connect two power generation devices or connect four or more power generation devices. The power generation system 101 in which the number of multiple power generation devices is generalized includes N (N>1) power generation devices from the first power generation device to the Nth power generation device, and N (N>1) heat exchangers from the first heat exchanger to the Nth heat exchanger that perform heat exchange between the heat transfer medium and supercritical CO2. The first heat exchanger performs heat exchange between the heat transfer medium heated by the heat source and the supercritical CO2 circulated for power generation of the first power generation device, and the (k + 1)th heat exchanger (1 < k < N) is configured such that the N power generation devices and the N heat exchangers are connected in a cascade manner so as to perform heat exchange between the heat transfer medium heat-exchanged in the kth heat exchanger and the supercritical CO2 circulated for power generation of the (k + 1)th power generation device.
[0041] Note that as the heat source 15, at least any one of a geothermal source, a fusion reactor (divertor, blanket, etc.), a nuclear reactor, sunlight, a hydrogen-based thermal power plant, high-level waste, biomass, etc. can be used. The power generation systems 101 and 101A using a geothermal source as the heat source 15 also include an aspect in which a heat transfer double pipe 30 embedded in a drilling hole 17 drilled by the laser drilling device 1 of the present invention is provided (there may be other aspects using other geothermal sources). By this aspect, a configuration example of a next-generation high-efficiency geothermal power generation system is realized. (Heat Exchanger) Hereinafter, a configuration example of the heat exchanger 33 used in the power generation systems 101 and 101A of FIGS. 10 and 11 will be described with reference to FIGS. 12(A) to (D).
[0042] As shown in FIG. 12(A), the heat exchanger 33 includes a container 35 in which an internal space for holding a heat transfer medium is formed, and a meandering pipe 36 through which supercritical CO2 flows, which is disposed in the internal space.
[0043] As shown in Figures 12(A) and (B), the container 35 has a medium inlet 37 for allowing the heat transport medium at a higher temperature to flow into the internal space, and a medium outlet 38 for allowing the heat transport medium that has become cooler due to heat exchange to flow out of the internal space, and the medium inlet 37 and the medium outlet 38 are located near one end of the container 35 (the upper end in the figure).
[0044] The container 35 further has a partition 41 for partially dividing the internal space into two regions: a high temperature region 42 on the medium inlet 37 side and a low temperature region 43 on the medium outlet 38 side (see FIG. 12(B)). The partition 41 leaves a gap 44 near the end opposite the one end (the lower end in the figure), and the two regions 42, 43 communicate with each other through the gap 44.
[0045] As shown in Fig. 12(C), the serpentine pipe 36 has a supercritical CO2 inlet 39 through which the supercritical CO2 is introduced and a supercritical CO2 outlet 40 through which the supercritical CO2 is discharged, and the serpentine pipe 36 is divided into a first section 45 from the supercritical CO2 inlet 39 and a second section 46 from the supercritical CO2 outlet 40. As shown in Fig. 12(D), the first section 45 of the serpentine pipe 36 is disposed in a low temperature region 43, and the second section 46 of the serpentine pipe 36 is disposed in a high temperature region 42. Note that a hole (not shown) may be formed in the partition 41, and a U-shaped pipe connecting the first section 45 and the second section 46 of the serpentine pipe 36 may pass through the hole.
[0046] Next, the heat distribution method of the heat exchanger 33 will be described with reference to FIG. The first section 45 of the serpentine path 36 from the supercritical CO2 inlet 39 is arranged in a low-temperature region on the medium outlet 38 side of the internal space of the container 35, and the supercritical CO2 introduced into the supercritical CO2 inlet 39 first passes through the first section 45 and is heated by the heat transport medium in the low-temperature region. Next, the supercritical CO2 heated by passing through the first section 45 flows through the second section 45 arranged in the high-temperature region on the medium inlet 37 side of the internal space of the container 35, is heated by the heat transport medium of higher temperature, and exits from the supercritical CO2 outlet 40. According to the heat exchanger 33 of this embodiment, excessive heat exchange in the high-temperature region can be mitigated in the low-temperature region, making it possible to achieve a homogeneous outlet temperature.
[0047] The heat exchange device according to the present embodiment is not limited to the above-mentioned configuration example, and other configurations can be suitably used. For example, a spiral shape can be used instead of a serpentine path, and the spiral heat exchange piping can be divided into two sections, such as the first section 45 and the second section 46 of the serpentine piping 36, and these sections can be disposed in the low temperature region 43 and the high temperature region 42, respectively. (Power generation equipment) A configuration example of the power generation device 50 shown in Figures 9 to 11 will be described with reference to Figure 14. Note that the power generation device used in the power generation system of the present invention is not limited to the power generation device shown in Figure 14, but includes any power generation device that generates electricity by rotating a gas turbine with supercritical CO2.
[0048] As shown in Fig. 14, the power generation device 50 includes a supercritical CO2 gas turbine 51 having an elongated integral rotating shaft 53 rotatable around one rotating shaft, a generator 65 connected to the end of the rotating shaft of the supercritical CO2 gas turbine 51, and a closed circulation system 80 for circulating supercritical CO2 heated by the heat source 15 or the heat exchanger 33 through the supercritical CO2 gas turbine. The supercritical CO2 gas turbine 51 includes a low-pressure compressor 54, a high-pressure compressor 55, a bypass compressor 56, and a gas turbine section 57 arranged to be rotated by supercritical CO2 compressed in sequence by the low-pressure compressor 54, the high-pressure compressor 55, and the bypass compressor 56, in series in the direction in which the supercritical CO2 flows along the rotating shaft.
[0049] The closed circulation system 80 is equipped with a first pipe 71 connecting the outlet side of the heat source 15 or the heat exchanger 33 to the inlet side of the gas turbine section 57, and a second pipe 72 that guides the supercritical CO2 gas from the outlet side of the gas turbine section 57 to the inlet side of the low-pressure compressor 54, in order to supply supercritical CO2 heated by the heat source 15 or the heat exchanger 33 to the gas turbine section 57 to rotate the rotating shaft 53.
[0050] In addition, the closed circulation system 80 of supercritical CO2 gas is equipped with a third pipe 73 that connects the outlet side of the bypass compressor 56 to the inlet side of the heat source 15 or the heat exchanger 33 in order to return a portion of the supercritical CO2 coming out of the bypass compressor 56 to the heat source 15 or the heat exchanger 33, and a fourth pipe 74 that branches off from the second pipe 72 and is connected to the inlet side of the bypass compressor 56 in order to return a portion of the supercritical CO2 coming out of the outlet side of the gas turbine section 57 to the bypass compressor 56.
[0051] Furthermore, the supercritical CO2 closed circulation system 80 includes a first regenerative heat exchanger 77a on the path of the second piping 72. The third piping 73 passes through the first regenerative heat exchanger 77a, whereby the supercritical CO2 returning from the bypass compressor 56 to the heat source 15 or the heat exchanger 33 is regenerated and heated by the supercritical CO2 exiting from the outlet side of the gas turbine section 57 and passing through the second piping 72.
[0052] The supercritical CO2 closed circulation system 80 further includes a fifth pipe 75 extending from the outlet side of the high-pressure compressor 55 and joining the third pipe 73 at a position upstream of the first regenerative heat exchanger 77a for returning a portion of the supercritical CO2 compressed by the high-pressure compressor 55 to the heat source 15 or the heat exchanger 33.
[0053] The closed circulation system 80 of supercritical CO2 further includes a second regenerative heat exchanger 77b downstream of the first regenerative heat exchanger 77a on the route of the second pipe 72 and upstream of the branch point of the fourth pipe 74. The fifth pipe 75 passes through the second regenerative heat exchanger 77b before joining the third pipe 73, whereby the supercritical CO2 returning from the high-pressure compressor 55 is regeneratively heated by the supercritical CO2 coming out of the outlet side of the gas turbine section 57. The supercritical CO2 from the high-pressure compressor 55, which has joined the third pipe 73, is further regeneratively heated by the first regenerative heat exchanger 77a together with the supercritical CO2 coming out of the bypass compressor 56 and passing through the third pipe 73.
[0054] The supercritical CO2 closed circulation system 80 further includes a pre-cooler 78 for cooling the supercritical CO2 flowing through the second pipe 72 between the second regenerative heat exchanger 77b and the inlet side of the low-pressure compressor 54. This makes it possible to supply lower-temperature supercritical CO2 to the supercritical CO2 gas turbine 51.
[0055] The supercritical CO2 closed circulation system 80 further includes a sixth pipe 76 that bypasses the gas from the outlet side of the low-pressure compressor 54 to the inlet side of the high-pressure compressor 55, and the sixth pipe 76 further includes an intermediate cooler 79 that cools a portion of the gas compressed by the low-pressure compressor 54 and supplies the cooled gas to the high-pressure compressor 55.
[0056] The main purpose of the compressors 54 to 56 here is to restore pressure with as little work as possible, and because compression efficiency decreases at high temperatures, it is necessary to operate at a low temperature and with the minimum power, and therefore after regaining pressure in the low-pressure compressor 54 and the high-pressure compressor 55, the refrigerant is reheated to the required return temperature by the regenerative heat exchangers 77a and 77b. However, the bypass compressor 56 is an exception, as it is designed to enable high-temperature operation. In the bypass compressor 56, the processing volume is reduced, but the power required is correspondingly greater.
[0057] The above is a description of the embodiment of the present invention, but the present invention is not limited to the above example and can be modified arbitrarily and suitably within the scope of the present invention. For example, in the above example, the laser drilling device 1 is configured in a straight line, but the present invention is not limited to this and can be configured in a shape having a bent portion. In this case, by arranging a mirror inside the laser inner tube 9 at the bent portion and reflecting the laser beam by the mirror, it is possible to propagate the laser beam along the laser inner tube 9 even if there is a bent portion. In addition, the laser drilling device 1 may be configured in a curved shape by configuring the laser inner tube 9 with an optical fiber.
[0058] Furthermore, in the above example, supercritical CO2 was supplied to the CO2 supply port 14, but the present invention is not limited to this. The CO2 used in the laser drilling device 1 of the present invention only needs to reach a supercritical state when injected from the supercritical CO2 port 5, and the present invention includes the case where the CO2 supplied to the laser supply port 14 and flowing through the CO2 supply path 11 is in a subcritical state or a subcritical state. This is because the deeper the drilling depth, the higher the underground temperature becomes, and the pressure of the CO2 supplied deep underground increases, so even if the CO2 supplied to the CO2 supply port 14 does not reach at least one of the critical pressure and the critical temperature, it may become supercritical deeper underground.
[0059] 8, supercritical CO2 is supplied at the inlet of the supercritical CO2 supply path, but the present invention is not limited to this example, and the present invention also includes a case where subcritical or subcritical CO2 is supplied at the inlet of the supercritical CO2 supply path as described above and is made supercritical deep underground. The heat transfer double pipe 30 may be configured such that the inner pipe 32 defines the supercritical CO2 supply path, and the space between the outer pipe 31 and the inner pipe 32 defines the supercritical CO2 return path.
[0060] Furthermore, the heat exchanger 33 shown in FIG. 13 is divided into two mutually communicating regions, a high temperature region and a low temperature region, but it may be divided into three or more mutually communicating regions (if divided into three, for example, a high temperature region, an intermediate temperature region, and a low temperature region), and each section of the heat exchange piping (serpentine piping 36) may be disposed in each region. [Explanation of symbols]
[0061] 1 Laser drilling equipment 1A Drilling System 2 Central shaft body 3 Rotating tip 3a Rotating protrusion 4 Laser Aperture 5 Supercritical CO2 port 6 First Casing 6a Rotating groove 7 Second Casing 8 Return flow path for crushed material 9 Laser Inner Tube 10 Laser optical path 11 CO2 supply path 12 Blades 13 Laser beam supply port 14 CO2 supply port 15, 15a Heat source 16. Collection port for crushed material 17 Borehole 18 Melt containing SiO2 precipitates 19 Crushed particles 20 Support configuration 21 Laser beam source 22 Supercritical CO2 generation source 23 CO2 Capture Section 24 CE Tank 25 Beam collimator 30 Heat transfer double tube 31 Outer tube 32 Inner tube 33(33a, 33b, 33c) Heat exchanger 34 Other types of generating equipment 35 Container 36 Serpentine piping 37 Media inlet 38 Media outlet 39 Supercritical CO2 inlet 40 Supercritical CO2 outlet 41 Partition 42 High temperature area 43 Low temperature region 44 Gap 45 First Division 46 Second Division 50 (50a, 50b, 50c) Power generation device 65 Generator 100 Power Generation System 101 Cascade power generation system (first modified example) 101A Cascade power generation system (second modified example)
Claims
1. supercritical CO ２ A circulating laser drilling device, a laser inner tube defining a laser optical path through which a laser beam passes; A first casing that covers the outer periphery of the laser inner tube, and a CO ２ the first casing defining a supply passage; A rotary tip portion attached to a tip of at least one of the laser inner tube and the first casing so as to be rotatable about an axial direction; a second casing covering an outer periphery of the first casing and defining a return flow path for crushed material between the first casing and the second casing; Equipped with The rotary tip is ２ CO supplied through the supply line ２ The laser aperture from which the laser beam propagated through the laser optical path is emitted and the supplied CO ２ is injected in a supercritical state ２ A laser drilling device having a port.
2. The rotary tip is ２ CO supplied from the supply line ２ 10. The laser drilling apparatus of claim 1, further comprising a blade that derives a rotational moment for rotating the rotatable tip from a flow of water.
3. The rotating tip is ２ The laser aperture is located at the center of the rotating tip, and the supercritical CO ２ The laser drilling system of claim 2 , wherein ports are disposed about the laser aperture.
4. The rotating tip is formed in a truncated cone shape, and a plurality of the supercritical CO ２ The laser drilling apparatus of claim 3 , wherein a port is formed in a side of the frustum of the cone and the laser aperture is formed in a frustum top of the frustum of the cone.
5. The CO ２ CO supplied to the supply line ２ The inlet pressure of CO ２ 2. The laser drilling apparatus of claim 1 , wherein the pressure is equal to or greater than the critical pressure of
6. 2. The laser drilling device according to claim 1, wherein the laser beam incident on the laser optical path has a beam width adjusted at a focusing point exiting the laser aperture by a combination of a plurality of beam collimators.
7. Supercritical CO using geothermal energy ２ A power generation system that generates power by heating a The supercritical CO according to any one of claims 1 to 6. ２ The laser drilling equipment is used to drill holes using a circulating laser. ２ A heat transfer double tube through which Supercritical CO heated by geothermal energy while circulating in the heat transfer double tube ２ at least one power generation device that utilizes the above-mentioned to rotate a gas turbine and a generator coupled to the gas turbine to generate electricity; Equipped with The heat transfer double tube is an outer tube having a closed tip portion and disposed with the closed tip portion facing downward; an inner tube having an open tip end and disposed inside the outer tube with the open tip end facing downward; A supercritical CO ２ The inner tube defines a supply path, and the inner passage of the inner tube extends from the open end of the inner tube through which heated supercritical CO ２ a power generation system defining a return path for the
8. The power generation system includes N power generation devices (N>1) from a first power generation device to an Nth power generation device, The first power generation device is a supercritical CO ２ This is used to rotate a gas turbine to generate electricity. Supercritical CO used for power generation in the kth power generation unit (1<k<N) ２ 8. The power generation system of claim 7, wherein the N power generation units are connected in a cascaded manner such that a k+1th power generation unit generates electricity using a k-th power generation voltage.
9. The supercritical CO used for power generation of the Nth power generation device. ２ At least a part of the supercritical CO ２ By returning it to the supply line, supercritical CO ２ The power generation system according to claim 8 , forming a circulation system.
10. Supercritical CO by heat source ２ A power generation system that generates power by heating a Heated supercritical CO ２ The present invention includes N (N>1) power generation devices from a first power generation device to an Nth power generation device, each of which rotates a gas turbine using a gas turbine generator connected to the gas turbine, and generates power by rotating the gas turbine generator, The first power generation device is a supercritical CO ２ This is used to rotate a gas turbine to generate electricity. Supercritical CO used for power generation in the kth power generation unit (1<k<N) ２ The N power generation devices are connected in a cascade manner so that the k+1th power generation device uses the k+1th power generation device; The heat source is a supercritical CO gas according to any one of claims 1 to 6. ２ A power generation system using geothermal heat from deep underground, drilled by a circulating laser drilling device.
11. The heat transfer medium heated by the heat source is circulated to produce supercritical CO ２ A power generation system that generates power by heating a Heated supercritical CO ２ N (N>1) power generation devices from a first power generation device to an Nth power generation device, each of which generates power by rotating a gas turbine using the above-mentioned gas turbine to rotate a generator connected to the gas turbine; The heat transport medium and supercritical CO ２ N (N>1) heat exchange devices from a first heat exchange device to an Nth heat exchange device, which exchange heat between the first heat exchange device and the Nth heat exchange device; Equipped with The first heat exchanger exchanges the heat transport medium heated by the heat source with the supercritical CO circulating for power generation by the first power generation device. ２ Heat exchange takes place between The k+1th heat exchanger (1<k<N) is a heat exchanger for transferring the heat transport medium that has been heat exchanged in the kth heat exchanger and the supercritical CO circulating for power generation of the k+1th power generation device. ２ The N power generation devices and the N heat exchangers are connected in a cascade manner to exchange heat between the N power generation devices and the N heat exchangers, The heat source is a supercritical CO gas according to any one of claims 1 to 6. ２ A power generation system using geothermal heat from deep underground, drilled by a circulating laser drilling device.
12. The power generation system according to claim 11 , wherein at least a part of the heat transport medium that has been heat exchanged in the Nth heat exchanger is heated by the heat source and circulated back to the first heat exchanger.
13. Each of the N heat exchangers includes a container having an internal space for holding a heat transport medium, and a supercritical CO ２ and a heat exchange pipe through which the heat exchanger flows. The container has a medium inlet for allowing a higher temperature heat transport medium to flow into the internal space, and a medium outlet for allowing the heat transport medium that has become lower in temperature due to heat exchange to flow out of the internal space, the medium inlet and the medium outlet being provided at a position closer to one end of the container, The container further has a partition for partially dividing the internal space into at least two regions, a high temperature region on the medium inlet side and a low temperature region on the medium outlet side, the partition leaving a gap near an end opposite to the one end, and the at least two regions communicating with each other through the gap, The heat exchange piping is a supercritical CO ２ Supercritical CO ２ Inlet and supercritical CO ２ Supercritical CO ２ and an outlet, and the heat exchange piping is ２ A first section from the inlet and supercritical CO ２ The second section is located near the exit. The power generation system of claim 11 , wherein the first section of the heat exchange piping is disposed in the low temperature region and the second section of the heat exchange piping is disposed in the high temperature region.
14. The power generating system according to claim 11 , wherein the heat transport medium is a liquid metal or a molten salt selected from the group consisting of Al, Ca, and Na.
Citation Information
Patent Citations
Ghost detection circuit
JP1983044868A
Coiled tubing drilling with supercritical carbon dioxide
US6347675B1