Power generation device for seafloor hot water

Abstract

A power generation unit (10) is provided with: a heat exchanger (2) which is provided immediately above or in a seafloor (91) and in which an internally flowing working fluid is heated by seafloor hot water not in contact with seawater on the seafloor (91); a turbine (3) which rotates by the working fluid flowing in the heat exchanger (2); a power generator (4) which generates power by using the rotation of the turbine (3) as power; and a condenser (5) which cools the working fluid used for the rotation of the turbine (3) by the seawater on the seafloor (91).

Description

Power generation device using submarine hot water

[0001] The present invention relates to a power generation device using submarine hot water.

[0002] In recent years, the use of structures called chimneys or mounds formed by the precipitation of metal components contained in submarine hot water with the heat source of magma from submarine volcanoes as mineral resources has been studied.

[0003] However, only very little consideration has been given to the use of the thermal energy of submarine hot water. In addition, submarine hot water is hot water at high temperature and high pressure, and contains many inorganic salts and metal components in high concentrations in the submarine crust. Therefore, when submarine hot water is cooled by seawater, scale is likely to precipitate. Scale becomes various obstacles in the use of submarine hot water.

[0004] An object of an embodiment of the present invention is to provide a power generation device suitable for power generation using submarine hot water. The power generation device for submarine hot water according to the viewpoint of the present invention is provided immediately above or in the submarine, and a heat exchanger in which a working fluid flowing inside is heated by submarine hot water that does not touch the seawater above the submarine, a turbine rotated by the working fluid flowing through the heat exchanger, a generator that generates power using the rotation of the turbine as power, and a condenser that cools the working fluid used for the rotation of the turbine with the seawater above the submarine.

[0005] Figure 1 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the first embodiment of the present invention. Figure 2 is a configuration diagram showing the state in which the power generation unit and seafloor equipment according to the first embodiment are separated. Figure 3 is a configuration diagram showing the configuration of a heat exchanger according to a modified example of the first embodiment. Figure 4 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the second embodiment of the present invention. Figure 5 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the third embodiment of the present invention. Figure 6 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the fourth embodiment of the present invention. Figure 7 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the fifth embodiment of the present invention. Figure 8 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the sixth embodiment of the present invention. Figure 9 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the seventh embodiment of the present invention. Figure 10 is a configuration diagram showing the configuration of a heat exchanger and a rotating plate according to the seventh embodiment. Figure 11 is a configuration diagram showing the configuration of a heat exchanger and a rotating plate according to a first modified example of the seventh embodiment. Figure 12 is a configuration diagram showing the configuration of a rotating plate according to a second modified example of the seventh embodiment. Figure 13 is a configuration diagram showing the configuration of a rotating plate according to a third modified example of the seventh embodiment. Figure 14 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the eighth embodiment of the present invention. Figure 15 is a configuration diagram showing an example of the configuration of a heat exchanger according to the eighth embodiment. Figure 16 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device according to the ninth embodiment of the present invention. Figure 17 is a configuration diagram showing an example of the configuration of a cover according to the ninth embodiment.

[0006] (First Embodiment) Figure 1 is a configuration diagram showing the configuration of a seafloor hydrothermal power generation device 30 according to the first embodiment of the present invention. Figure 2 is a configuration diagram showing the power generation unit 10 and seafloor equipment 20 according to the first embodiment separated. The same parts in the drawings are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0007] The submarine hydrothermal power generation device 30 is a device that generates electricity using the heat of submarine hydrothermal fluids accumulated in a submarine hydrothermal reservoir 93 located in the crust 92 beneath the seabed 91. The submarine hydrothermal power generation device 30 comprises a power generation unit 10 and submarine equipment 20. The power generation unit 10 is the main body for generating electricity. The submarine equipment 20 is equipment for securing a place to install the power generation unit 10 on the seabed 91. The power generation unit 10 can be removed from the submarine equipment 20 and transported by a ship's crane or the like. For example, the power generation unit 10 is unitized so that it can be transported to a factory on land for maintenance, inspection, or repair.

[0008] The power generation unit 10 includes a control device 1, a heat exchanger 2, a turbine 3, a generator 4, a condenser 5, a pump 6, a sensor 7, piping 11, a unit case 12, and a power transmission cable 13.

[0009] The control device 1 is a device that controls each component of the seafloor hydrothermal power generation system 30. The control device 1 performs various functions by performing calculations using a computer. For example, based on the detection results of the sensor 7, the control device 1 starts, stops, or monitors the operating status of the seafloor hydrothermal power generation system 30.

[0010] The control device 1 may be housed in a pressure-resistant case configured to withstand the environment, such as the water pressure of the deep sea. The seabed 91 where the hydrothermal reservoirs 93 are located is mainly at depths of about 700 m to 1,500 m. Equipment used in such a seabed 91 requires water pressure resistance of 7 MPa to 20 MPa. For this reason, it is desirable that the pressure-resistant case be configured to withstand such an environment.

[0011] The heat exchanger 2 has a spiral configuration in which piping (hot water channels) through which the working fluid flows is formed. The piping on the inlet side of the heat exchanger 2 is connected to the piping through which the working fluid is supplied from the condenser 5 via the pump 6. The piping on the outlet side of the heat exchanger 2 is connected to the piping through which the working fluid supplied to the turbine 3 flows.

[0012] The heat exchanger 2 is installed so as to protrude from the bottom of the unit case 12 that encloses the entire power generation unit 10. In the figure, the heat exchanger 2 is installed so that its helical central axis is in the vertical direction, but it may also be installed so that its helical central axis is in the horizontal direction. The heat exchanger 2 is inserted into a hole connecting the seabed 91 to the seafloor hydrothermal reservoir 93 or into the seafloor hydrothermal reservoir 93. The heat exchanger 2 receives thermal energy from the seafloor hydrothermal fluid by boiling the working fluid flowing inside the heat exchanger 2 using the heat of the seafloor hydrothermal fluid in the seafloor hydrothermal reservoir 93. The steam working fluid boiled by the heat exchanger 2 is sent to the turbine 3 via the piping 11.

[0013] Note that the heat exchanger 2 is not limited to the shape and configuration described in this embodiment, but may have any shape and configuration. For example, as shown in Figure 3, the heat exchanger 2a may have a configuration in which a spiral flow path (piping) through which the working fluid flows is formed inside a cylindrical member. The seafloor hydrothermal fluid flows inside (through a through hole in the center of the cylinder) and outside the cylindrical member, thereby heating the working fluid flowing inside the cylindrical heat exchanger 2a.

[0014] Furthermore, the heat exchanger 2 may be a heat exchanger of an existing configuration. For example, any type and shape of heat exchanger is acceptable, such as a partition type, regenerative type, direct contact type, shell-and-tube type, plate type, Jungstrom type, double-tube type, finned-tube type, spiral type, corrugated-fin type, or compact type.

[0015] The working fluid can be any substance depending on the environment of the seafloor hydrothermal power generation device 30 or the condition of the seafloor hydrothermal fluid. For example, the working fluid may be a fluorocarbon alternative, a hydrocarbon, a mixture of ammonia and water, or a silicone oil, or any other heat transfer medium.

[0016] The turbine 3 rotates using steam working fluid supplied from the heat exchanger 2 via piping 11. By rotating, the turbine 3 converts the thermal energy of the working fluid into rotational energy. The working fluid that has rotated the turbine 3 is sent to the condenser 5 via piping 11. The turbine 3 may be housed in a pressure-resistant case designed to withstand environments such as the water pressure of the deep sea.

[0017] The generator 4 is a generator for binary power generation. The rotating shaft of the generator 4 is connected in conjunction with the rotation of the turbine 3. The generator 4 generates electricity as the turbine 3 rotates. In this way, the generator 4 converts the rotational energy of the turbine 3 into electrical energy. The generator 4 transmits the generated electricity to onshore demand facilities via the power transmission cable 13. A portion of the electricity generated by the generator 4 may be supplied to any equipment within the submarine hydrothermal power generation device 30.

[0018] Furthermore, as long as the generator 4 generates electricity through the rotation of the turbine 3, the generator 4 may be connected to the turbine 3 in any way. For example, magnets may be provided on the rotating shaft of the generator 4 and on the turbine 3, and the rotational force of the turbine 3 may be transmitted to the rotating shaft of the generator 4 by the magnetic force of the magnets. In addition, the generator 4 may be housed in a pressure-resistant case so as to withstand the pressure of the deep sea.

[0019] The condenser 5 cools and condenses the working fluid sent from the turbine 3 via the piping 11 using cold seawater. The condenser 5 has a configuration in which the piping through which the working fluid flows is formed in a spiral shape. In the figure, the condenser 5 is installed so that the central axis of the spiral is horizontal, but it may also be installed so that the central axis of the spiral is vertical. The condenser 5 is installed so as to protrude to the outside (for example, the top) from the unit case 12 that surrounds the entire power generation unit 10. The cold seawater is the seawater surrounding the power generation unit 10, and is the seawater above the seabed 91. The working fluid is cooled in the condenser 5 and returns to a completely liquid state. The liquid working fluid is sent to the heat exchanger 2 via the piping 11.

[0020] The condenser 5 may be an existing plate type in which the flow path of the working fluid is composed of plates, or it may be a condenser of any other configuration, similar to the heat exchanger 2. The condenser 5 may also be called a condenser.

[0021] Pump 6 is installed in the middle of the piping 11 that carries the working fluid from the condenser 5 to the heat exchanger 2. Pump 6 pumps the working fluid from the condenser 5 to the heat exchanger 2. As a result, the working fluid circulates through the piping 11 within the power generation unit 10. Pump 6 can be installed anywhere in the power generation unit 10, and there may be any number of pumps installed.

[0022] Sensor 7 is a sensor for measuring the state of the seafloor hydrothermal fluid surrounding the heat exchanger 2. For example, sensor 7 is a temperature sensor for measuring the temperature of the seafloor hydrothermal fluid. Sensor 7 may also include a pressure sensor for measuring the pressure of the seafloor hydrothermal fluid, or sensors for measuring other states of the seafloor hydrothermal fluid. Furthermore, there may be more than one sensor 7. For example, multiple sensors of the same type (e.g., multiple temperature sensors) may be provided, or multiple types of sensors (e.g., a temperature sensor and a pressure sensor) may be provided. In this embodiment, sensor 7 may be omitted.

[0023] The piping 11 forms a flow path for the working fluid. The piping 11 is arranged so that a closed circuit is formed in the order of heat exchanger 2, turbine 3, and condenser 5. As a result, the working fluid flows in a sequential circulation through the heat exchanger 2, turbine 3, and condenser 5. It is desirable that the piping 11 connecting the heat exchanger 2 and turbine 3 be covered with insulating material to prevent the working fluid temperature from dropping.

[0024] The unit case 12 encloses the entire power generation unit 10 and protects each component of the power generation unit 10. The unit case 12 is a pressure-resistant case designed to withstand environments such as the water pressure of the deep sea. The temperature and pressure inside the unit case 12 may be controlled. For example, the temperature inside the unit case 12 may be controlled to be equivalent to room temperature on land, and the pressure to be close to atmospheric pressure. The unit case 12 does not have to be airtight, and the inside of the unit case 12 may be exposed to the water temperature and pressure environment of the installation location. In this case, each component is housed in the pressure-resistant case, and the piping is covered with insulation material.

[0025] A connection portion is provided on the lower outer surface of the unit case 12, which connects to the coupler 22 of the submarine equipment 20. The connection portion is configured to be detachable from the coupler 22. When transporting the power generation unit 10 to land, the connection portion is disconnected from the coupler 22.

[0026] The seabed equipment 20 is installed on the seabed 91, where a hydrothermal reservoir 93 is located below. The seabed equipment 20 includes a casing pipe 21, a coupler 22, and an inner cover 23.

[0027] The casing pipe 21 is provided to maintain the inner wall of the hole drilled in the crust 92 so that it reaches from the seabed 91 to the seafloor hydrothermal reservoir 93. The heat exchanger 2 of the power generation unit 10 is inserted into the casing pipe 21.

[0028] The coupler 22 is installed on top of the casing pipe 21 and is a device for connecting to the power generation unit 10. The coupler 22 connects the power generation unit 10 to the seabed equipment 20, so that the power generation unit 10 acts as a cover that seals the top of the casing pipe 21. As a result, the inside of the casing pipe 21 is filled with seabed hydrothermal fluids that are blown up from below.

[0029] The inner cover 23 is a cover that seals the top of the casing pipe 21 when the power generation unit 10 is removed from the seabed equipment 20. The inner cover 23 prevents a chimney from forming in the casing pipe 21 and prevents the inside of the casing pipe 21 from being filled with sediment or other debris.

[0030] Here, a chimney is a chimney-like structure formed by precipitated scale. Because chimneys contain a large amount of metallic components, they have thermal conductivity. Therefore, hydrothermal fluids flowing through a chimney formed in cold seawater are easily cooled by the cold seawater through the chimney. Consequently, the hydrothermal fluids spewing from a chimney are at a lower temperature than the hydrothermal fluids that flowed through the chimney.

[0031] When the power generation unit 10 is connected to the submarine equipment 20, the inner cover 23 opens so as to be pushed into the interior (lower side) of the casing pipe 21 at the lower part of the power generation unit 10 (for example, the heat exchanger 2). Therefore, the inner cover 23 is automatically opened when the power generation unit 10 is connected to the submarine equipment 20. The inner cover 23 may be configured in any way as long as it functions to close the top of the casing pipe 21 when the power generation unit 10 is not installed in the submarine equipment 20.

[0032] Referring to Figure 1, the operation of the seafloor hydrothermal power generation device 30 will be described. The power generation unit 10 is installed so as to close the opening at the top of the casing pipe 21. The inside of the casing pipe 21 is filled with seafloor hydrothermal fluid blown up from the seafloor hydrothermal reservoir 93. The heat exchanger 2 inserted into the casing pipe 21 is heated by the seafloor hydrothermal fluid. As a result, the working fluid flowing inside the heat exchanger 2 boils.

[0033] The boiling working fluid is sent from the heat exchanger 2 to the turbine 3. The working fluid sent to the turbine 3 rotates the turbine 3, which in turn rotates the rotating shaft of the generator 4, causing the generator 4 to generate electricity. The electricity generated by the generator 4 is transmitted to the ground via the power transmission cable 13.

[0034] The working fluid used to rotate turbine 3 is sent to condenser 5. The working fluid sent to condenser 5 is cooled by cold seawater and becomes completely liquid. The working fluid, now back into liquid, is sent to heat exchanger 2 by pump 6.

[0035] The working fluid sent to the heat exchanger 2 is heated again and sent to the turbine 3. This circulation of the working fluid allows the generator 4 to continue generating electricity.

[0036] As the seafloor hydrothermal fluid that has heated the heat exchanger 2 cools, it sinks. Meanwhile, seafloor hydrothermal fluid is blown up from the seafloor hydrothermal fluid reservoir 93 from below the casing pipe 21. As a result, the seafloor hydrothermal fluid around the heat exchanger 2 circulates, and fresh (high-temperature) seafloor hydrothermal fluid constantly heats the heat exchanger 2.

[0037] The control device 1 may also monitor the condition of the seafloor hydrothermal fluid around the heat exchanger 2 based on the detection results of the sensor 7. For example, the condition may include temperature and pressure, but at least temperature. Furthermore, if the control device 1 determines that the condition of the seafloor hydrothermal fluid is unsuitable for the operation of the seafloor hydrothermal power generation device 30, it may stop the operation of the seafloor hydrothermal power generation device 30. For example, a condition in which the seafloor hydrothermal fluid is unsuitable for the operation of the seafloor hydrothermal power generation device 30 is a temperature at which the working fluid flowing through the heat exchanger 2 cannot be properly heated, or a temperature at which scale is likely to adhere to the heat exchanger 2.

[0038] According to this embodiment, a heat exchanger 2 is inserted into a casing pipe 21 provided in a hole that reaches from the seabed 91 to the seabed hydrothermal reservoir 93, and the working fluid is heated by the heat exchanger 2 to perform binary power generation, thereby efficiently utilizing the heat of the seabed hydrothermal reservoir to generate electricity.

[0039] For example, if the heat exchanger 2 is installed on the seabed 91, the seabed hydrothermal fluid is cooled by the cold seawater, making it easy for a chimney to form. Chimneys generally have thermal conductivity, and the temperature of the seabed hydrothermal fluid passing through the chimney tends to decrease. In contrast, in this embodiment, the working fluid can be heated by the heat of the seabed hydrothermal fluid supplied directly from the seabed hydrothermal reservoir 93 without being cooled by the cold seawater, thus efficiently heating the working fluid.

[0040] Furthermore, the condenser 5 cools the working fluid using the cold seawater surrounding it, thereby returning the working fluid to a liquid state. Therefore, there is no concern about the loss of the cooling source, and the working fluid can be cooled efficiently.

[0041] (Second Embodiment) Figure 4 is a configuration diagram showing the configuration of a submarine hydrothermal power generation device 30A according to the second embodiment of the present invention.

[0042] The submarine hydrothermal power generation device 30A is the same as the submarine hydrothermal power generation device 30 according to the first embodiment shown in Figure 1, but with the power generation unit 10 replaced by the power generation unit 10A and the coupler 22 removed from the submarine equipment 20. Other aspects are the same as in the first embodiment.

[0043] In the power generation unit 10A, the heat exchanger 2 is provided so as to protrude from the side surface of the unit case 12A. In the figure, the heat exchanger 2 is provided such that the spiral central axis of the pipe is in the horizontal direction, but it may be provided such that the spiral central axis is in the vertical direction. The lower part of the unit case 12A is formed in a shape suitable for installation on the seabed 91. The seabed 91 where the power generation unit 10A is installed may be artificially formed, or a connection part connected to the power generation unit 10A may be provided as in the coupler 22 according to the first embodiment. In other respects, the power generation unit 10A is the same as the power generation unit 10 according to the first embodiment.

[0044] Referring to FIG. 4, the operation of the undersea hot water power generation device 30A will be described. Since the upper part of the casing pipe 21 is open, undersea hot water constantly blows out from the casing pipe 21. For this reason, the inside of the casing pipe 21 is filled with new undersea hot water ejected from the undersea hot water reservoir 93. Therefore, the heat exchanger 2 inserted into the casing pipe 21 is continuously heated by the new undersea hot water. In other respects, it is the same as the undersea hot water power generation device 30 according to the first embodiment.

[0045] According to the present embodiment, even if the power generation unit 10A is installed at a location other than the upper part of the casing pipe 21, the same operational effects as those of the first embodiment can be obtained. For example, when the flow rate of the undersea hot water blown up from the casing pipe 21 can be sufficiently ensured, the present embodiment can be adopted.

[0046] (Third Embodiment) FIG. 5 is a configuration diagram showing the configuration of an undersea hot water power generation device 30B according to the third embodiment of the present invention.

[0047] The undersea hot water power generation device 30B is obtained by replacing the power generation unit 10 with a power generation unit 10B in the undersea hot water power generation device 30 according to the first embodiment shown in FIG. 1. Other points are the same as those in the first embodiment.

[0048] The power generation unit 10B is connected to the coupler 22 with a slight gap from the upper part of the casing pipe 21. On the bottom surface of the unit case 12B, an upward slope is formed from the center to the outside so as to secure a flow path for the submarine hot water blown out from the casing pipe 21. Further, a support member 14 is provided to support the power generation unit 10B by securing a gap between the bottom surface of the unit case 12B and the upper part of the casing pipe 21. In other respects, the power generation unit 10B is the same as the power generation unit 10 according to the first embodiment.

[0049] Referring to FIG. 5, the operation of the submarine hot water power generation device 30B will be described. There is a gap between the upper part of the casing pipe 21 and the bottom surface of the power generation unit 10B. Old submarine hot water is pushed out from this gap by the new submarine hot water supplied from the submarine hot water reservoir 93, and the old submarine hot water is discharged into the sea above the seabed 91. For this reason, the inside of the casing pipe 21 is always filled with new submarine hot water. Therefore, the heat exchanger 2 inserted into the casing pipe 21 is continuously heated by the new submarine hot water. In other respects, the submarine hot water power generation device 30 according to the first embodiment is the same.

[0050] According to the present embodiment, in addition to the effects of the first embodiment, the following effects can be obtained.

[0051] By installing the power generation unit 10B so that a gap can be formed between it and the opening of the casing pipe 21, the submarine hot water that has heated the heat exchanger 2 can be discharged from this gap, and new submarine hot water can be supplied around the heat exchanger 2. Thereby, the heat exchanger 2 can be continuously heated by the high-temperature submarine hot water supplied from the submarine hot water reservoir 93.

[0052] When the submarine hot water heats the heat exchanger 2, its temperature drops. When the temperature of the submarine hot water drops, the heating effect of the heat exchanger 2 decreases, and scale is likely to precipitate. When scale precipitates and adheres to the heat exchanger 2, the heating efficiency of the working fluid by the submarine hot water further decreases.

[0053] In contrast, by creating a gap between the power generation unit 10B and the casing pipe 21, the cooled seafloor hydrothermal water can be discharged into the cold seawater. As a result, fresher seafloor hydrothermal water supplied from the seafloor hydrothermal reservoir 93 is supplied around the heat exchanger 2, allowing the working fluid to be heated efficiently.

[0054] (Fourth Embodiment) Figure 6 is a configuration diagram showing the configuration of the submarine hydrothermal power generation device 30C according to the fourth embodiment of the present invention.

[0055] The submarine hydrothermal power generation device 30C is the same as the submarine hydrothermal power generation device 30 of the first embodiment shown in Figure 1, except that the power generation unit 10 is replaced with the power generation unit 10C. Other aspects are the same as in the first embodiment.

[0056] The power generation unit 10C is the same as the power generation unit 10 according to the first embodiment, except that the control device 1 is replaced with the control device 1C, and a hot water discharge pipe 15 and a control valve 16 are added. Any number of hot water discharge pipes 15 and control valves 16 can be provided, as long as one or more of each are provided. In other respects, the power generation unit 10C is the same as the power generation unit 10 according to the first embodiment.

[0057] The control device 1C controls the opening and closing of the control valve 16 based on the detection result of the sensor 7. In other respects, the control device 1C is the same as the control device 1 according to the first embodiment.

[0058] The hydrothermal discharge pipe 15 is installed inside the power generation unit 10C and is a pipe for discharging the seafloor hydrothermal water inside the casing pipe 21 into the sea above the seabed 91. The intake port of the hydrothermal discharge pipe 15 is located at the opening of the casing pipe 21 on the bottom surface of the unit case 12C. The outlet port of the hydrothermal discharge pipe 15 is located on the side surface of the unit case 12C. A pump may be installed in the hydrothermal discharge pipe 15 to facilitate the discharge of seafloor hydrothermal water.

[0059] The control valve 16 is installed in the hydrothermal discharge pipe 15. The control valve 16 is a valve whose opening and closing operation is controlled by the control device 1C. Normally, the control valve 16 is closed. When the control valve 16 is opened, the seafloor hydrothermal fluid inside the casing pipe 21 is discharged from the hydrothermal discharge pipe 15. Note that any device other than the control valve 16 may be installed as long as it can block and open the flow of seafloor hydrothermal fluid inside the hydrothermal discharge pipe 15. For example, instead of the control valve 16, an openable or closable cover may be installed at the inlet or outlet of the hydrothermal discharge pipe 15, and the opening and closing of this cover may be controlled by the control device 1C.

[0060] Referring to Figure 6, the operation of the seafloor hydrothermal power generation device 30C will be described. Here, we will mainly describe the operation that differs from that of the first embodiment, while other operations are the same as those of the seafloor hydrothermal power generation device 30 according to the first embodiment.

[0061] The control device 1C determines the state of the seafloor hydrothermal fluid around the heat exchanger 2 based on the detection results of the sensor 7. The state includes at least temperature, and preferably both temperature and pressure.

[0062] If the control device 1C determines that the seafloor hydrothermal fluid around the heat exchanger 2 is in a state unsuitable for the operation of the seafloor hydrothermal power generation device 30C, it outputs a command signal to open the control valve 16. The state unsuitable for operation is determined in the same way as in the first embodiment. As a result, the control valve 16 is opened, and the seafloor hydrothermal fluid inside the casing pipe 21 is discharged into the sea above the seabed 91. Meanwhile, new seafloor hydrothermal fluid is supplied to the inside of the casing pipe 21 from the seafloor hydrothermal fluid reservoir 93. In this way, the seafloor hydrothermal fluid inside the casing pipe 21 is replaced.

[0063] After the control valve 16 is opened, the control device 1C outputs a command signal to close the control valve 16. For example, the control device 1C outputs a command signal to close the control valve 16 when it determines that the seafloor hydrothermal fluid around the heat exchanger 2 is in a state suitable for operation, or after a predetermined time has elapsed since the control valve 16 was opened. The predetermined time is longer than the time required for the seafloor hydrothermal fluid inside the casing pipe 21 to be replaced.

[0064] In this way, the control device 1C maintains the seafloor hydrothermal water around the heat exchanger 2 in a state suitable for the operation of the seafloor hydrothermal power generation device 30C. Alternatively, the control device 1C may periodically open the control valve 16 and periodically replace the seafloor hydrothermal water inside the casing pipe 21, regardless of the detection results of the sensor 7.

[0065] According to this embodiment, in addition to the effects and advantages of the first embodiment, the following effects and advantages can be obtained.

[0066] The control device 1C monitors the condition of the seafloor hydrothermal fluid inside the casing pipe 21, and, depending on the condition of the seafloor hydrothermal fluid, opens the control valve 16 provided in the hydrothermal fluid discharge pipe 15, thereby releasing the seafloor hydrothermal fluid around the heat exchanger 2 (for example, seafloor hydrothermal fluid with a reduced temperature) into the seawater above the seabed 91. As a result, good quality seafloor hydrothermal fluid is supplied around the heat exchanger 2, improving the heating efficiency of the working fluid by the heat exchanger 2.

[0067] (Fifth Embodiment) Figure 7 is a configuration diagram showing the configuration of the seafloor hydrothermal power generation device 30D according to the fifth embodiment of the present invention.

[0068] The submarine hydrothermal power generation device 30D is the same as the submarine hydrothermal power generation device 30C according to the fourth embodiment shown in Figure 6, except that the power generation unit 10C is replaced with the power generation unit 10D. Other aspects are the same as in the first embodiment.

[0069] The power generation unit 10D is the same as the power generation unit 10C according to the fourth embodiment, except that the control device 1C is replaced with the control device 1D, and the hot water discharge pipe 15 and control valve 16 are replaced with a motor 17 and a stirrer 18. In other respects, the power generation unit 10D is the same as the power generation unit 10C according to the fourth embodiment.

[0070] The control device 1D controls the drive of the motor 17 based on the detection result of the sensor 7. In other respects, the control device 1D is the same as the control device 1C according to the fourth embodiment.

[0071] Motor 17 is the power source for operating the agitator 18. Motor 17 is driven and stopped by command signals from the control device 1D. Motor 17 is supplied with power from the generator 4.

[0072] The agitator 18 is a device that uses the motor 17 as a power source to agitate the seafloor hydrothermal fluid inside the casing pipe 21. The agitator 18 is equipped with a propeller shaft and a propeller. The propeller is attached to the tip of the propeller shaft. The propeller shaft is connected to the rotating shaft of the motor 17. For example, the propeller shaft of the agitator 18 is positioned to be inserted into the spiral center of the heat exchanger 2.

[0073] Furthermore, any shape or configuration of a stirrer may be used, not limited to the stirrer 18 described in this embodiment, as long as it is configured to agitate the seafloor hydrothermal fluid. For example, the stirrer 18 may have multiple propellers mounted on a single propeller shaft, or multiple stirrers 18 may be mounted on the rotating shaft of the motor 17.

[0074] Referring to Figure 7, the operation of the seafloor hydrothermal power generation device 30D will be described. Here, we will mainly describe the operation that differs from that of the first embodiment, while other operations are the same as those of the seafloor hydrothermal power generation device 30 according to the first embodiment.

[0075] The control device 1D determines the state of the seafloor hydrothermal fluid around the heat exchanger 2 based on the detection results of the sensor 7. The determination of the state of the seafloor hydrothermal fluid is the same as in the fourth embodiment.

[0076] If the control device 1D determines that the seafloor hydrothermal fluid around the heat exchanger 2 is not suitable for the operation of the seafloor hydrothermal power generation device 30D, it outputs a command signal to drive the motor 17.

[0077] When the motor 17 is driven, the propeller rotates via the propeller shaft, agitating the seafloor hydrothermal fluid inside the casing pipe 21. As the seafloor hydrothermal fluid inside the casing pipe 21 is agitated, the cooled seafloor hydrothermal fluid around the heat exchanger 2 diffuses, and new seafloor hydrothermal fluid from the seafloor hydrothermal fluid reservoir 93 is supplied around the heat exchanger 2. This improves the heating efficiency of the heat exchanger 2 by the seafloor hydrothermal fluid.

[0078] After the motor 17 has been driven, the control device 1D may output a command signal to stop the motor 17. For example, the timing for stopping the motor 17 is determined based on the state of the seafloor hydrothermal fluid or the driving time, similar to the timing for closing the control valve 16 according to the fourth embodiment.

[0079] In this way, the control device 1D keeps the seafloor hydrothermal water around the heat exchanger 2 in a state suitable for the operation of the seafloor hydrothermal power generation device 30D. The control device 1D may also periodically drive the motor 17 to agitate the seafloor hydrothermal water inside the casing pipe 21, regardless of the detection results of the sensor 7.

[0080] According to this embodiment, in addition to the effects and advantages of the first embodiment, the following effects and advantages can be obtained.

[0081] The control device 1D monitors the condition of the seafloor hydrothermal fluid inside the casing pipe 21 and, according to the condition of the seafloor hydrothermal fluid, drives the motor 17 to diffuse the poorly conditioned seafloor hydrothermal fluid around the heat exchanger 2. As a result, good-condition seafloor hydrothermal fluid is supplied around the heat exchanger 2, improving the heating efficiency of the working fluid by the heat exchanger 2.

[0082] (Sixth Embodiment) Figure 8 is a configuration diagram showing the configuration of a submarine hydrothermal power generation device 30E according to the sixth embodiment of the present invention.

[0083] The submarine hydrothermal power generation device 30E is the same as the submarine hydrothermal power generation device 30B according to the third embodiment shown in Figure 5, except that the power generation unit 10B is replaced with the power generation unit 10E. Other aspects are the same as in the first embodiment.

[0084] The power generation unit 10E is the same as the power generation unit 10B according to the third embodiment, with the control device 1B replaced by the control device 1E, and the motor 17 and agitator 18 according to the fifth embodiment added, as well as the heat exchanger case 31 and heat transfer oil 32 further added. The sensor 7 may or may not be provided. In other respects, the power generation unit 10E is the same as the power generation unit 10B according to the third embodiment.

[0085] The control device 1E controls the drive of the motor 17. The control device 1E may control the drive of the motor 17 based on time, or, as in the fifth embodiment, it may control the drive of the motor 17 based on the detection result of the sensor 7. The sensor 7 may measure the state of the seafloor hydrothermal fluid, the state of the heat transfer oil 32, or both. In other respects, the control device 1E is the same as the control device 1B in the third embodiment.

[0086] The heat exchanger case 31 is attached to the lower part of the power generation unit 10E. The heat exchanger case 31 is a pressure-resistant case configured to withstand environments such as the water pressure of the deep sea. The heat exchanger case 31 may be made of a material that is resistant to scale buildup, or it may be coated to prevent scale buildup. The inside of the heat exchanger case 31 is filled with heat transfer oil 32. The heat exchanger case 31 houses the heat exchanger 2 and the agitator 18 inside the heat transfer oil 32.

[0087] The heat transfer oil 32 is an oil that acts as a heat transfer medium, mediating the transfer of heat from the seafloor hydrothermal fluid to the working fluid flowing through the heat exchanger 2. Specifically, the heat transfer oil 32 is heated by the seafloor hydrothermal fluid, and the heated heat transfer oil 32 heats the working fluid flowing through the heat exchanger 2. After heating the working fluid, the heat transfer oil 32 cools down and is heated again by the seafloor hydrothermal fluid. By repeating this process, the seafloor hydrothermal fluid heats the working fluid through the heat transfer oil 32. Note that any liquid that can perform the role of a heat transfer medium is acceptable, not limited to the heat transfer oil 32, but any liquid with any composition.

[0088] Here, we will mainly describe the parts of the motor 17 and stirrer 18 that differ from those of the fifth embodiment, and will omit descriptions of other parts as they are the same as those of the fifth embodiment.

[0089] The motor 17 is driven and stopped by command signals from the control device 1E. When the motor 17 is driven, the agitator 18 agitates the heat transfer oil 32 inside the heat exchanger case 31. The motor 17 may be driven based on the detection results of the sensor 7, may be driven periodically, or may be driven continuously. The agitator 18 agitates the heat transfer oil 32 so that the heat transfer oil 32 properly transfers the heat of the seabed hydrothermal fluid to the working fluid.

[0090] Referring to Figure 8, the operation of the submarine hydrothermal power generation device 30E will be described. The submarine hydrothermal power generation device 30E operates in the same manner as the third embodiment, except that the submarine hydrothermal water heats the heat exchanger case 31 instead of the heat exchanger 2. The control device 1E controls the motor 17 to drive, thereby stirring the heat transfer oil 32 with the agitator 18. As the heat transfer oil 32 is stirred, it is heated by the submarine hydrothermal water through the heat exchanger case 31, and heats the working fluid flowing to the heat exchanger 2.

[0091] In this embodiment, as in the third embodiment, a gap is provided between the bottom surface of the unit case 12B and the top of the casing pipe 21 to ensure a flow path for the seafloor hydrothermal fluid to be blown into the cold seawater. However, as in the first embodiment, the bottom surface of the unit case 12B may be installed so as to completely block the top of the casing pipe 21. Even in this case, the seafloor hydrothermal fluid can heat the heat exchanger case 31 in the same way as the heat exchanger 2 in the first embodiment.

[0092] According to this embodiment, in addition to the effects and advantages of the first embodiment, the following effects and advantages can be obtained.

[0093] By covering the heat exchanger 2 with a pressure-resistant heat exchanger case 31, it is possible to completely prevent scale from adhering to the heat exchanger 2. Furthermore, by configuring the heat transfer oil 32 filling the inside of the heat exchanger case 31 to be agitated by the agitator 18, the heat from the seabed hydrothermal fluid can be efficiently transferred to the working fluid flowing into the heat exchanger 2.

[0094] Furthermore, by providing a gap in the upper part of the casing pipe 21 to ensure a flow path for the seafloor hydrothermal fluid that is ejected into the cold seawater, the same effects and advantages as in the third embodiment can be obtained.

[0095] (Seventh Embodiment) Figure 9 is a configuration diagram showing the configuration of the seafloor hydrothermal power generation device 30F according to the seventh embodiment of the present invention.

[0096] The submarine hydrothermal power generation device 30F is the same as the submarine hydrothermal power generation device 30D according to the fifth embodiment shown in Figure 7, except that the power generation unit 10D is replaced with the power generation unit 10F. Other aspects are the same as in the fifth embodiment.

[0097] The power generation unit 10F is the same as the power generation unit 10D according to the fifth embodiment, except that the control device 1D and the stirrer 18 are replaced with the control device 1F and the rotating plate 33, respectively. The sensor 7 may or may not be provided. In other respects, the power generation unit 10F is the same as the power generation unit 10D according to the fifth embodiment.

[0098] The control device 1F controls the drive of the motor 17. The control device 1F may control the drive of the motor 17 based on time, or, as in the fifth embodiment, it may control the drive of the motor 17 based on the detection result of the sensor 7. In other respects, the control device 1F is the same as the control device 1D in the fifth embodiment.

[0099] Figure 10 is a configuration diagram showing the configuration of the heat exchanger 2 and the rotating plate 33 according to this embodiment. The rotating plate 33 rotates inside the spiral of the heat exchanger 2, acting as a stirrer to agitate the seafloor hydrothermal water inside the casing pipe 21, and is also a device for removing the boundary film (temperature boundary layer) formed on the heat transfer surface of the heat exchanger 2 and scraping off scale adhering to the piping. The rotating plate 33 has a rectangular plate-shaped portion, with one end attached to the rotation axis. The length of the plate-shaped portion in the direction perpendicular to the rotation axis (radial direction) is slightly shorter than, but approximately the same as, the radius of the spiral of the heat exchanger 2. The length of the plate-shaped portion in the direction of the rotation axis is the same as, or slightly longer than, the height of the heat exchanger 2.

[0100] The rotation axis of the rotating plate 33 is connected to the rotation axis of the motor 17. The rotating plate 33 is inserted into the spiral interior of the heat exchanger 2. The plate-shaped portion of the rotating plate 33 is positioned to protrude outward from the rotation axis. The end of the plate-shaped portion on the piping side of the heat exchanger 2 (opposite the rotation axis) is positioned so as not to contact the piping of the heat exchanger 2, or to be only lightly in contact with it. As the rotating plate 33 rotates around the rotation axis, the boundary film is removed and heat exchange is performed efficiently, and the scale that has formed on the spiral interior of the piping is scraped off by the plate-shaped portion of the rotating plate 33.

[0101] Figure 11 is a configuration diagram showing the configuration of the heat exchanger 2 and the rotating plate 33a according to the first modified example of this embodiment. The rotating plate 33a of the first modified example has a configuration in which the plate-shaped portion is deformed compared to the rotating plate 33 shown in Figure 10. Here, we will mainly explain the differences between the rotating plate 33a of the first modified example and the rotating plate 33 shown in Figure 10.

[0102] The radial length of the plate-shaped portion of the rotating plate 33a is slightly larger than the spiral radius of the heat exchanger 2. The length of the plate-shaped portion of the rotating plate 33a in the direction of rotation is slightly larger than the height of the heat exchanger 2. A rectangular cutout extending vertically is made in the plate-shaped portion of the rotating plate 33a where the piping of the heat exchanger 2 is located. The rotating plate 33a is positioned so that the piping of the heat exchanger 2 fits into the cutout in the plate-shaped portion. Therefore, the plate-shaped portion of the rotating plate 33a is positioned to be close to both the inner and outer sides of the spiral of the piping. As the rotating plate 33a rotates around its axis of rotation, the boundary film on the inner or outer side of the spiral of the piping is removed, and the scale formed protruding on both sides is scraped off by the plate-shaped portion of the rotating plate 33a.

[0103] In this embodiment, the power generation unit 10F is installed so as to completely seal the upper part of the casing pipe 21, similar to the first embodiment. However, similar to the third embodiment, a gap may be provided between the bottom surface of the unit case 12 and the upper part of the casing pipe 21 to secure a flow path for seafloor hydrothermal fluid to be ejected into the cold seawater. In this case, an upward flow of seafloor hydrothermal fluid is generated inside the casing pipe 21.

[0104] Referring to Figures 12 and 13, a second modified rotating plate 33b and a third modified rotating plate 33c that utilize the rising current of hydrothermal vents on the seabed will be described. The second and third modified rotating plates 33b and 33c are configured in which a curve 331 is provided on the upper part of the plate-shaped portion of the rotating plates 33 and 33a shown in Figures 10 and 11, respectively.

[0105] The curvature 331 is shaped to facilitate rotation of the rotating plates 33b and 33c around the axis of rotation when subjected to the rising current of hydrothermal vents on the seabed. The shape that facilitates rotation may be one in which the rotating plates 33b and 33c rotate solely by the rising current of hydrothermal vents on the seabed, or it may be one in which the rotating plates 33b and 33c do not rotate unless driven by the motor 17. By facilitating rotation (agitation) of the rotating plates 33b and 33c, the power consumption of the motor 17 is reduced.

[0106] Here, we will explain the limitations on the function of the curvature 331. When the rotating plates 33b and 33c rotate in response to the rising current of hydrothermal fluids on the seabed, the thermal energy of the hydrothermal fluids is converted into kinetic energy due to the rotation of the rotating plates 33b and 33c, causing the temperature of the hydrothermal fluids to decrease. As a result, the heating effect of the heat exchanger 2 by the hydrothermal fluids on the seabed decreases.

[0107] Therefore, it is desirable that the curvature 331 be shaped so that the rotating plates 33b and 33c do not rotate excessively due to the rising current of hydrothermal vents on the seabed. The power generation unit 10F may also be configured to prevent the rotating plates 33b and 33c from rotating too much. For example, the power generation unit 10F may monitor the decrease in power consumption of the motor 17 due to the rising current of hydrothermal vents on the seabed so as not to be less than the decrease in power generation of the power generation unit 10F due to the decrease in temperature of the hydrothermal vents on the seabed, and control the rotation of the rotating plates 33b and 33c.

[0108] Furthermore, there may be any number of curves 331 on the rotating plates 33b and 33c, and they may be provided anywhere on the rotating plates 33b and 33c. In addition, the curves 331 are not limited to those provided; any shape that facilitates the rotation of the rotating plates 33b and 33c due to the rising current of hydrothermal vents on the seabed is acceptable, such as a twist or torsion. Moreover, the curves 331 may include shapes that prevent the rotating plates 33b and 33c from rotating too much, or shapes or parts that prevent the rotating plates 33b and 33c from rotating too much may be provided on the rotating plates 33b and 33c or the power generation unit 10F.

[0109] Referring to Figure 9, the operation of the seafloor hydrothermal power generation device 30F will be described. Here, we will mainly describe the operation that differs from that of the fifth embodiment, while other operations are the same as those of the seafloor hydrothermal power generation device 30D according to the fifth embodiment.

[0110] The control device 1F periodically or continuously outputs a command signal to drive the motor 17. Similar to the fourth embodiment, the control device 1F may determine the state of the seafloor hydrothermal fluid around the heat exchanger 2 based on the detection result of the sensor 7 and output a command signal to drive the motor 17.

[0111] When the motor 17 is driven, the rotating plate 33 rotates, agitating the seafloor hydrothermal fluid inside the casing pipe 21 and scraping off the scale adhering to the heat exchanger 2.

[0112] After the motor 17 has been driven, the control device 1F may output a command signal to stop the motor 17. For example, the timing for stopping the motor 17 is determined based on the state of the seafloor hydrothermal fluid or the driving time, similar to the timing for closing the control valve 16 according to the fourth embodiment.

[0113] According to this embodiment, in addition to the effects and advantages of the first embodiment, the following effects and advantages can be obtained.

[0114] By using the rotating plate 33, the scale adhering to the heat exchanger 2 is removed while the seafloor hydrothermal water inside the casing pipe 21 is stirred, thereby maintaining an appropriate heating efficiency of the working fluid by the heat exchanger 2.

[0115] Furthermore, if rotating plates 33b and 33c are used that are shaped to facilitate rotation (agitation) by the rising current of hydrothermal fluids on the seabed, the power consumption of the motor 17 can be reduced.

[0116] (Eighth Embodiment) Figure 14 is a configuration diagram showing the configuration of a submarine hydrothermal power generation device 30G according to the eighth embodiment of the present invention.

[0117] The submarine hydrothermal power generation device 30G is the submarine hydrothermal power generation device 30A according to the second embodiment shown in Figure 4, with the power generation unit 10A replaced by the power generation unit 10G. The power generation unit 10G is the same as the power generation unit 10A according to the second embodiment, with the heat exchanger 2 replaced by the heat exchanger 2G, and at least one ultrasonic transducer 19 attached to the heat exchanger 2G. Other aspects are the same as in the second embodiment.

[0118] The heat exchanger 2G is a heat exchanger configured so that hydrothermal fluids from the seabed pass through its interior. For example, the heat exchanger 2G is a shell-and-tube type heat exchanger. In other respects, the heat exchanger 2G is the same as the heat exchanger 2 according to the first embodiment.

[0119] The ultrasonic transducer 19 is attached to the surface of the heat exchanger 2G. The ultrasonic transducer 19 is a device that generates ultrasonic vibrations (micro-vibrations). The vibrations of the ultrasonic transducer 19 suppress the adhesion of scale to the heat exchanger 2G.

[0120] The ultrasonic transducer 19 may be of any type. For example, the ultrasonic transducer 19 may be an electrostrictive type that vibrates when a voltage is applied, or a magnetostrictive type that vibrates when a magnetic field is applied. Power may be supplied to the ultrasonic transducer 19 from the generator 4, or from a source other than the generator 4. There may be one or more ultrasonic transducers 19. The ultrasonic transducer 19 may not be limited to the surface of the heat exchanger 2G, but may also be installed inside the heat exchanger 2G, or anywhere else. The ultrasonic transducer 19 may be controlled by the control device 1, such as being operated or monitored.

[0121] Referring to Figure 15, an example of the configuration of heat exchanger 2G will be described. In this example, heat exchanger 2G is a shell-and-tube type heat exchanger.

[0122] The heat exchanger 2G comprises a shell 201, a plurality of tubes 202, a working fluid inlet 203, a working fluid outlet 204, and a plurality of baffles 205.

[0123] The shell 201 corresponds to the body of the heat exchanger 2G and includes an outer shell that covers the outside of the heat exchanger 2G. The inner wall of the shell 201 forms part of the flow path for seafloor hydrothermal fluids. The shell 201 is cylindrical or tubular in shape.

[0124] Multiple tubes 202 are provided inside the shell 201, parallel to the longitudinal direction of the shell 201. The tubes 202 are channels through which hydrothermal fluid flows in from one end of the shell 201 in the longitudinal direction and out from the other end of the shell 201. There may be one or more tubes 202.

[0125] The working fluid inlet 203 is located at the bottom of the side of the shell 201. The working fluid inlet 203 is an inlet through which the working fluid flows. The working fluid inlet 203 is connected to a pipe through which the working fluid is supplied from the condenser 5. The working fluid that flows into the working fluid inlet 203 flows into the interior of the shell 201.

[0126] The working fluid outlet 204 is located on the upper side of the shell 201. The working fluid outlet 204 is the outlet through which the working fluid flows out. The working fluid outlet 204 is connected to the piping through which the working fluid supplied to the turbine 3 flows. Alternatively, the working fluid inlet 203 may be located on the upper side of the shell 201, and the working fluid outlet 204 may be located on the lower side of the shell 201.

[0127] Multiple baffles 205 are plate-shaped members provided inside the shell 201, forming part of the flow path for the working fluid. The baffles 205 are fixed to the inner wall of the shell 201 alternately from the left and right, starting from the top of the shell 201. The baffles 205 are fixed perpendicular to the inner wall of the shell 201. One end of the baffle 205 is fixed to the inner wall of the shell 201, while the other unfixed end of the baffle 205 has a gap between it and the inner wall of the shell 201. When viewed from above inside the shell 201, the baffle 205 fixed on the left and the baffle 205 fixed on the right overlap each other. The working fluid flows through the gap between the unfixed end of the baffle 205 and the inner wall of the shell 201, and between two adjacent baffles 205 on the left and right, avoiding the baffles 205 provided on the left and right. As a result, the working fluid flows inside the shell 201 from bottom to top, meandering from side to side.

[0128] Referring to Figure 14, the operation of the seafloor hydrothermal power generation device 30G will be described. Here, we will mainly describe the operation that differs from that of the second embodiment, while other operations are the same as those of the seafloor hydrothermal power generation device 30A according to the second embodiment.

[0129] Similar to the second embodiment, the heat exchanger 2G inserted into the casing pipe 21 is continuously heated by fresh seafloor hydrothermal fluid. The ultrasonic transducer 19 provided in the heat exchanger 2G continuously generates ultrasonic vibrations. This suppresses the adhesion of scale deposited from the seafloor hydrothermal fluid cooled by the heat exchange in the heat exchanger 2G to the heat exchanger 2G. For example, if a channel for seafloor hydrothermal fluid to flow is formed inside the heat exchanger 2G, the adhesion of scale inside the heat exchanger 2G is suppressed.

[0130] According to this embodiment, by providing the ultrasonic transducer 19 on the heat exchanger 2G, it is possible to suppress the adhesion of scale deposited from seafloor hydrothermal fluids to the heat exchanger 2G.

[0131] In this description, the submarine hydrothermal power generation device 30A according to the second embodiment is described as the basic configuration, but any submarine hydrothermal power generation device 30 to 30H according to any embodiment may be used as the basic configuration. Also, the heat exchanger 2G to which the ultrasonic transducer 19 is attached may be the same as the heat exchanger 2 according to the first embodiment, or it may be any other type and shape of heat exchanger.

[0132] (Ninth Embodiment) Figure 16 is a configuration diagram showing the configuration of the submarine hydrothermal power generation device 30H according to the ninth embodiment of the present invention.

[0133] The submarine hydrothermal power generation device 30H is the same as the submarine hydrothermal power generation device 30 of the first embodiment shown in Figure 1, except that the submarine equipment 20 is replaced with submarine equipment 20H. Other aspects are the same as in the first embodiment.

[0134] Here, we will describe the case where the submarine equipment 20H is installed directly below the power generation unit 10, but the submarine equipment 20H and the power generation unit 10 may be installed in any positional relationship. For example, the submarine equipment 20H may be installed next to the power generation unit 10.

[0135] The submarine equipment 20H comprises an ultrasonic transducer 19, a cover 24, and a base 25 according to the eighth embodiment.

[0136] The cover 24 is installed to cover the area where hydrothermal vents are ejected from the seabed 91. The heat exchanger 2 is housed inside the cover 24. As a result, the hydrothermal vents ejected from the seabed 91 are retained inside the cover 24. The heat exchanger 2 is heated by the hydrothermal vents retained inside the cover 24. The area where hydrothermal vents are ejected may be a natural hydrothermal vent or an artificial vent that has been drilled or fabricated. In addition, a casing pipe 21 may be provided in the hole including the vent, as in the first embodiment.

[0137] The cover 24 is dome-shaped or hemispherical. The cover 24 is installed directly beneath the power generation unit 10. For example, the upper part of the cover 24 is connected to the bottom surface of the unit case 12 of the power generation unit 10. The upper part of the cover 24 may be provided with a connection part that can be attached to and detached from the bottom surface of the unit case 12. However, it is desirable that a gap be provided between the cover 24 and the unit case 12 so that hydrothermal fluids containing scale can be discharged from the opening provided in the upper part of the cover 24.

[0138] Furthermore, the cover 24 may have any shape and configuration as long as it allows seafloor hydrothermal fluid to accumulate inside. The cover 24 is not limited to being located below the power generation unit 10; it may also be located next to the power generation unit 10, or anywhere on the seabed 91.

[0139] Furthermore, the unit case 12 may be installed in any way. For example, the lower part of the unit case 12 may be supported by the upper part of the cover 24, by the base 25, or by the seabed 91. Support members may also be provided to support the unit case 12.

[0140] The base 25 is equipment for installing the cover 24 on the seabed 91. By installing the base 25, the cover 24 can be installed on the seabed 91 in a stable state. The base 25 is designed to fit the cover 24. The base 25 may have any shape and configuration. Alternatively, the cover 24 may be directly fixed to the seabed 91 without the base 25.

[0141] The ultrasonic transducer 19 is attached to the surface of the cover 24. By providing the ultrasonic transducer 19, scale buildup on the cover 24 is prevented, similar to the eighth embodiment. There may be any number of ultrasonic transducers 19, and they may be attached anywhere on the cover 24. For example, the ultrasonic transducer 19 may be attached to the inner surface of the cover 24. Note that the ultrasonic transducer 19 may not be provided at all.

[0142] Referring to Figure 17, an example of the configuration of the cover 24 will be described. The cover 24 is dome-shaped. The cover 24 is provided with a plurality of first outlets 241 and second outlets 242. A plurality of ultrasonic transducers 19 are attached to the surface of the cover 24.

[0143] The first outlets 241 are provided at regular intervals around the entire circumference of the lower part of the cover 24. The second outlets 242 are provided at the top of the cover 24. The first outlets 241 are provided to discharge seafloor hydrothermal fluids. The second outlets 242 are provided to discharge seafloor hydrothermal fluids containing scale. There may be any number of first outlets 241 and second outlets 242, and they may be provided anywhere. Furthermore, there is no need to distinguish between the first outlets 241 and second outlets 242, and they may be used interchangeably.

[0144] Referring to Figure 16, the operation of the seafloor hydrothermal power generation device 30H will be described. Here, the operation that differs from the first embodiment will be mainly described, while other operations are the same as those of the seafloor hydrothermal power generation device 30 according to the first embodiment.

[0145] Inside the cover 24, hydrothermal fluids ejected from the seabed 91 accumulate. The accumulated hydrothermal fluids are then pushed out through the first outlet 241 and the second outlet 242 by newly ejected hydrothermal fluids. Therefore, the heat exchanger 2 housed inside the cover 24 is constantly heated by fresh hydrothermal fluids. In addition, the ultrasonic transducer 19 attached to the cover 24 vibrates to prevent scale buildup on the cover 24. Other aspects are the same as those of the hydrothermal fluid power generation device 30 according to the first embodiment.

[0146] According to this embodiment, in addition to the effects and advantages of the first embodiment, the following effects and advantages can be obtained.

[0147] By providing a cover 24 to cover the area where seafloor hydrothermal fluids are ejected, seafloor hydrothermal fluids that have not come into contact with the seawater above the seabed 91 can be retained inside the cover 24. This allows the heat exchanger 2 to be heated inside the cover 24, which is located just above the seabed 91. This reduces the operational and installation work of the seafloor hydrothermal power generation device 30H.

[0148] For example, when installing the seafloor hydrothermal power generation device 30 according to the first embodiment, a hole large enough to accommodate the heat exchanger 2 inside the casing pipe 21 must be excavated. In contrast, with this embodiment, the hole can be small as long as a sufficient amount of seafloor hydrothermal fluid is released to heat the heat exchanger 2. Therefore, natural seafloor hydrothermal outlets can be utilized, reducing or eliminating the need for excavation work.

[0149] Furthermore, since the heat exchanger 2 is located inside the cover 24 above the seabed 91, maintenance and inspection of the heat exchanger 2 become easier compared to the case where the heat exchanger 2 is located inside the casing pipe 21, as in the first embodiment.

[0150] Furthermore, if the ultrasonic transducer 19 is provided on the cover 24, it is possible to prevent scale from adhering to the cover 24.

[0151] Furthermore, additional advantages and modifications may readily arise for those skilled in the art. Therefore, the present invention in its broader aspects is not limited to the specific detailed and representative embodiments described herein. Accordingly, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

Claims

1. A power generation device comprising: a heat exchanger located just above or within the seabed, in which a working fluid flowing inside is heated by seafloor hydrothermal water that is not in contact with the seawater above the seabed; a turbine that rotates with respect to the working fluid flowing through the heat exchanger; a generator that generates electricity using the rotation of the turbine as power; and a condenser that cools the working fluid used to rotate the turbine with seawater above the seabed.

2. The power generation apparatus according to claim 1, wherein the heat exchanger is inserted into a casing pipe that reaches from the seabed to a seafloor hydrothermal reservoir, and the working fluid is heated by the seafloor hydrothermal fluid inside the casing pipe.

3. The power generation device according to claim 1, comprising a pressure-resistant case that houses the turbine and the generator and is configured to withstand the water pressure at the seabed.

4. The power generation device according to claim 3, further comprising a connection portion provided on the outside of the pressure-resistant case and configured to be detachably connected to the seabed equipment installed on the seabed.

5. The power generation apparatus according to claim 1, further comprising a sensor for detecting a state including at least the temperature of the seafloor hydrothermal fluid.

6. The power generation apparatus according to claim 5, further comprising a control device that monitors the state of the seafloor hydrothermal fluid based on the detection results from the sensor.

7. The power generation apparatus according to claim 2, comprising: a pipe for discharging the seafloor hydrothermal water inside the casing pipe onto the seabed; an opening / closing unit for opening and closing to block and open the flow of seafloor hydrothermal water in the pipe; and a control device for controlling the opening / closing unit to discharge the seafloor hydrothermal water inside the casing pipe onto the seabed.

8. The power generation device according to claim 7, comprising a sensor for detecting the state of the seafloor hydrothermal fluid, including at least the temperature, wherein the control device determines the state of the seafloor hydrothermal fluid based on the detection result from the sensor, and controls the operation of the opening / closing part based on the determined state of the seafloor hydrothermal fluid.

9. The power generation apparatus according to claim 1, comprising: a stirrer for agitating the seafloor hydrothermal water; a motor for supplying power to the stirrer; and a control device for controlling the drive of the motor.

10. The power generation device according to claim 9, comprising a sensor for detecting the state of the seafloor hydrothermal fluid, including at least the temperature, wherein the control device determines the state of the seafloor hydrothermal fluid based on the detection result from the sensor, and controls the motor based on the determined state of the seafloor hydrothermal fluid.

11. The power generation apparatus according to claim 9, wherein the agitator is equipped with a propeller for agitating the seafloor hydrothermal water.

12. The power generation apparatus according to claim 9, wherein the agitator includes a plate-shaped portion that agitates the seafloor hydrothermal water while scraping off scale adhering to the heat exchanger.

13. The power generation apparatus according to claim 12, wherein the plate-shaped portion of the agitator includes a shape that facilitates rotation in order to agitate the water due to the rising current of the seafloor hydrothermal fluid.

14. The power generation device according to claim 2, comprising the casing pipe.

15. The power generation device according to claim 1, further comprising an ultrasonic transducer attached to the heat exchanger and generating ultrasonic vibrations to prevent scale buildup on the heat exchanger.

16. The power generation apparatus according to claim 1, wherein the heat exchanger is provided inside a cover that covers an outlet from which the seafloor hydrothermal water is ejected onto the seabed, and the working fluid is heated by the seafloor hydrothermal water that remains inside the cover.

17. The power generation device according to claim 16, further comprising the cover.

18. The power generation device according to claim 16, further comprising an ultrasonic transducer attached to the cover and generating ultrasonic vibrations to prevent scale from adhering to the cover.

19. A method for generating electricity, comprising: heating a working fluid flowing inside a heat exchanger located just above or within the seabed with seafloor hydrothermal water that is not in contact with seawater above the seabed; rotating a turbine with the working fluid flowing through the heat exchanger; generating electricity with a generator using the rotation of the turbine as power; and cooling the working fluid used to rotate the turbine with seawater above the seabed.

20. The power generation method according to claim 19, wherein the heat exchanger is inserted into a casing pipe that reaches from the seabed to a seafloor hydrothermal reservoir, and the working fluid is heated by the seafloor hydrothermal fluid inside the casing pipe.

21. The power generation method according to claim 19, wherein the heat exchanger is provided inside a cover that covers an outlet from which the seafloor hydrothermal water is blown onto the seabed, and the working fluid is heated by the seafloor hydrothermal water that remains inside the cover.

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