Control of heat transfer fluid through magma-driven heat exchangers.

Abstract

Apparatus, system, and method for controlling a molten salt heat exchanger. The system includes a magma-driven heat exchanger extending at least partially within a magma body containing magma. Molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form a heated molten salt. A second heat exchanger disposed external to the magma-driven heat exchanger uses the heated molten salt to heat a working fluid from a first temperature to a second temperature higher than the first temperature. The system also includes a set of fluid conduits forming a flow path that transports the molten salt in a loop between the magma-driven heat exchanger and the second heat exchanger. A fluid control device is included for controlling the flow of the molten salt through the flow path.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Patent Application No. 18 / 166,699, filed March 2, 2023 (U.S. Provisional Patent Application No. 63 / 439,810, filed January 18, 2023), which is incorporated herein by reference in its entirety. [Technical Field]

[0002] The present invention relates to the field of fluid management, and more particularly to controlling the flow of molten salt through a system including a magma-driven heat exchanger. [Background technology]

[0003] Water is a common heat transfer fluid because it is chemically stable and generally usable over a relatively large temperature range. However, water undergoes a phase transition from liquid to gas at sufficiently high temperatures. The liquid form of water has a higher thermal conductivity and a higher heat capacity than the gaseous form of water, i.e., steam. At increasingly higher temperatures, thicker walls are required to accommodate the steam flowing through fluid conduits, containment vessels, and heat exchangers. Thicker heat exchanger walls reduce the rate of heat transfer. Summary of the Invention [Means for solving the problem]

[0004] A first embodiment of the present invention is directed to a system for controlling the flow of molten salt through a magma-driven heat exchanger. The system includes a magma-driven heat exchanger extending at least partially within a magma body containing magma. The molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form a heated molten salt. A second heat exchanger disposed external to the magma-driven heat exchanger uses the heated molten salt to heat a working fluid from a first temperature to a second temperature higher than the first temperature. The system also includes a set of fluid conduits forming a flow path that transports the molten salt in an endless loop between the magma-driven heat exchanger and the second heat exchanger. A fluid control device is included for controlling the flow of the molten salt through the flow path.

[0005] A second embodiment of the present invention is directed to an apparatus for controlling the flow of molten salt through a magma-driven heat exchanger. The apparatus includes a memory storing instructions and a processor communicatively coupled to the memory. The processor is configured to execute the instructions to obtain first temperature data of heated molten salt transported from a magma-driven heat exchanger extending at least partially within a magma body containing magma. The molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form the heated molten salt. The processor is also configured to execute the instructions to obtain second temperature data of cooled molten salt transported from a second heat exchanger disposed external to the magma-driven heat exchanger. The second heat exchanger converts the heated molten salt to cooled molten salt by heating a working fluid from a first temperature to a second temperature higher than the first temperature. The processor is also configured to execute the instructions to generate control signals for controlling operation of one or more fluid control devices configured to control the flow of the molten salt based on at least one of the first temperature data and the second temperature data.

[0006] A third embodiment of the present invention is directed to a method for controlling the flow of molten salt through a magma-driven heat exchanger. The method includes obtaining first temperature data of heated molten salt delivered from a magma-driven heat exchanger extending at least partially within a magma body containing magma. The molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form the heated molten salt. The method also includes obtaining second temperature data of cooled molten salt delivered from a second heat exchanger disposed external to the magma-driven heat exchanger. The second heat exchanger converts the heated molten salt to cooled molten salt by heating the working fluid from a first temperature to a second temperature higher than the first temperature. The method also includes generating control signals for controlling operation of one or more fluid control devices configured to control the flow rate of the molten salt based on at least one of the first temperature data and the second temperature data.

[0007] Other aspects, embodiments, and features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. In the figures, each identical or substantially similar component illustrated in various figures is represented by a single numeral or designation. For clarity, not every component is labeled in every figure. Also, not every component of each embodiment of the invention shown is labeled unless an explanation is necessary for one of ordinary skill in the art to understand the invention. [Brief explanation of the drawings]

[0008] The features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as its preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of illustrative embodiments when read in connection with the accompanying drawings.

[0009] [Figure 1] FIG. 1 is a simplified schematic diagram of a system for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger according to an exemplary embodiment. [Figure 2] FIG. 2 is another schematic diagram of a system for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger in accordance with an illustrative embodiment. [Figure 3] 1 is a schematic illustration of a cross-sectional view of a magma well in accordance with an illustrative embodiment; [Figure 4A] 4A-4C are schematic diagrams of the upper and lower portions, respectively, of the magma well of FIG. 3, in accordance with an illustrative embodiment; [Figure 4B] 4A-4C are schematic diagrams of the upper and lower portions, respectively, of the magma well of FIG. 3, in accordance with an illustrative embodiment; [Figure 5A] 1 is a schematic diagram illustrating the placement of a temperature sensor according to various exemplary embodiments. [Figure 5B] 1 is a schematic diagram illustrating the placement of a temperature sensor according to various exemplary embodiments. [Figure 6]FIG. 1 is a schematic diagram of a networked system for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger according to an exemplary embodiment. [Figure 7] FIG. 1 is a schematic diagram of an apparatus for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger according to an exemplary embodiment. [Figure 8] 1 is a flowchart of a process for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Molten salts can be used as heat transfer fluids to harness heat from magma sources. The heat can then be transferred to a working fluid, allowing the working fluid to perform work. For example, molten salts heated by a magma-driven heat exchanger can pass through the heat exchanger to heat water to form a working fluid, such as steam, which can be used to generate electricity. Alternatively, heat from the molten salt can be used to drive endothermic reactions. Examples of some types of salts that can be used as molten salts include chlorides, bromides, fluorides, nitrates, and organic salts. Nitrates have the potential for use in heat transfer applications due to their low melting points, high operating temperatures, low vapor pressure, low toxicity, and low corrosivity. Nitrates can be eutectic blends of salts such as sodium nitrate and potassium nitrate.

[0011] Controlling the flow of molten salt through a magma-driven heat exchanger, and therefore through a system that includes a magma-driven heat exchanger, is important for a number of reasons. For example, without flow control, the molten salt may remain in the magma-driven heat exchanger for an excessive amount of time, resulting in breakdown of the molten salt and affecting its thermal properties. Excessively hot molten salt may also damage system components. On the other hand, molten salt that flows too slowly through the system's fluid conduits that transport the molten salt may lose too much heat and begin to solidify.

[0012] By recognizing the need to control the flow of molten salt through a magma-driven heat exchanger and a system implementing a magma-driven heat exchanger based on multiple inputs of temperature sensors, i.e., temperature data, the present invention can measure the cooled molten salt entering the magma-driven heat exchanger and the heated molten salt exiting the magma-driven heat exchanger, monitor the steady-state and transient magma-thermal conditions of the system, and use a fluidic device, such as a variable frequency drive (VFD) pump, to adjust the flow rate of the molten salt. The flow rate of the molten salt can be adjusted, for example, to prevent operation at temperatures that could damage system components (e.g., by freezing the salt at too low a temperature or by damaging system materials at too high a temperature) and / or to improve the efficiency of system operation (e.g., by providing molten salt at or near an optimal temperature for the process facilitated by the magma-driven heat exchanger). Thus, the present invention is integrated into the practical application of systems and methods for improving the efficiency and operating life of systems implementing a magma-driven heat exchanger. In a non-limiting embodiment, the flow rate of the molten salt is adjusted based on a temperature difference, as described in more detail in the following disclosure.

[0013] 1 is a simplified schematic diagram of a system for controlling the flow of molten salt through a magma-driven heat exchanger 102 according to an example embodiment. System 100 is generally configured to utilize heat from magma in a magma chamber or well 300 to heat molten salt flowing through system 100. The molten salt can then be used to heat a working fluid from a first temperature to a second temperature higher than the first temperature. The heated working fluid can be used to perform work, such as generating electricity or providing heat to drive an endothermic reaction.

[0014] The molten salt can be heated by absorbing heat from the surface and from a magma well 300 that extends at least partially into the magma body containing the magma. The heated molten salt can then be transported to a heat exchanger 102 located outside of the magma well 300 (see FIG. 3 and the corresponding description below). Heat from the molten salt can then be transferred to a working fluid 104 that enters the heat exchanger 102 at a first temperature and exits the heat exchanger 102 at a second temperature higher than the first temperature. In a non-limiting embodiment, the working fluid 104 can enter the heat exchanger 102 as a fluid condensate 104a, i.e., in a liquid state, and exit the heat exchanger 102 as a working gas 104b, i.e., in a gaseous state. In other embodiments, the flow of molten salt through the system 100 and / or the heat exchanger 102 can be controlled to determine the properties of the working fluid exiting the heat exchanger, such as the temperature of the working fluid and / or the state of the working fluid, e.g., liquid state versus gaseous state.

[0015] As used herein, and with particular reference to FIG. 3 , the molten salt 318 leaving the magma well 300 can alternatively be referred to as “heated molten salt” 318b, which can be distinguished from the molten salt entering the magma well 300, which can alternatively be referred to as “cooled molten salt” 318a. The cooled molten salt 318a transported back into the magma well 300 reforms the heated molten salt 318b to continue the process of producing a gaseous working fluid in a continuous process. Thus, the magma well 300 can alternatively be referred to as a magma-driven heat exchanger.

[0016] Returning to FIG. 1 , the molten salt may be transported through the system 100 by a set of fluid conduits 108. As used herein, the term "set" can mean one or more. Thus, a set of fluid conduits can be one or more fluid conduits, such as pipes connecting various pieces of equipment to allow the molten salt to flow through an endless loop linking the magma well 300 and the heat exchanger 102 located outside the magma well 300. The set of fluid conduits 108 can define a flow path for the molten salt, represented by arrow 110, which travels in a counterclockwise direction through the system 100.

[0017] Control of the flow of molten salt through system 100 can be achieved by a fluid control device, such as a pump 112, operably coupled to a set of fluid conduits 108. Pump 112 may be one or more pumps distributed throughout system 100 to control the flow of molten salt through the set of fluid conduits 108 via a variable motor control mechanism, such as a variable frequency drive (VFD), integrated with or operably coupled to pump 112. The variable motor control mechanism enables pump 112 to control the flow rate of molten salt through magma well 300 to control the heat exchange between the magma and the molten salt. A flow rate of molten salt through magma well 300 that is too fast will prevent the molten salt from absorbing enough heat to exchange with the working fluid in heat exchanger 102, while a flow rate that is too slow will cause the molten salt to overheat, resulting in degradation of the molten salt and / or potential damage to system 100 components. Depleted molten salt can require evacuating the depleted molten salt from the system 100 and replenishing with new salt, a very time-consuming and expensive process. During these downtimes, operation of the system 100 may be impossible, resulting in reduced efficiency. Furthermore, molten salt flowing too quickly through the heat exchanger 102 may inadequately exchange heat with the working fluid 104, while molten salt flowing too slowly through the heat exchanger 102 may exchange too much heat with the working fluid 102.

[0018] One or more fluid vessels can be coupled to the set of fluid conduits 108, i.e., disposed within the flow path 110. In the non-limiting example shown in FIG. 1, the system 100 includes a hot tank 114 and a cold tank 116 for storing heated molten salt 318b and cooled molten salt 318a, respectively (see FIG. 3). Referring to both FIGS. 1 and 3, at least one benefit of the one or more fluid vessels is the ability to control the flow rate of molten salt 318 through individual portions of the flow path 110. In the absence of one or more fluid vessels, increasing the flow rate of molten salt 318 through the set of fluid conduits 108 by pump 112 would result in a proportional increase in flow rate throughout the entire system 100. For example, if the temperature of the heated molten salt 318b is too high, the pump 112 can increase the flow rate of cooled molten salt 318a flowing through the magma well 300, so that the heated molten salt 318b can achieve a desired temperature. The high temperature tank 114 can accommodate an increased volume of heated molten salt 318b without affecting the flow rate of the heated molten salt 318b through the heat exchanger 102, and as a result, the heat transfer of the working fluid is not affected by the increased flow rate of cooled molten salt 318a through the magma well 300.

[0019] 1, one or more check valves may be incorporated throughout the system 100 to prevent unwanted backflow of the molten salt 318. In this exemplary embodiment of FIG. 1, check valves 118 are included in a set of fluid conduits upstream from the magma well 300 to prevent backflow of heated molten salt 318b from the magma well 300 into the cryogenic tank 116.

[0020] 2 is a schematic diagram of another example system 200 for controlling the flow of molten salt 318 through a magma-driven heat exchanger 102, according to one example embodiment. System 200 is similar to system 100 depicted in FIG. 1 , but includes a set of temperature sensors 202 positioned throughout to collect temperature data of the molten salt 318 flowing through a set of conduits 108 of system 200 or to collect temperature data of the working fluid 104 flowing through a set of conduits 204. Non-limiting examples of temperature sensors 202 can include heat transducers, thermocouples, or probes mounted on the outside of the set of fluid conduits 108, exposed to the fluid flow through a sidewall of the set of fluid conduits 108, or a combination of the two. Example mountings of temperature sensors 202 are described in more detail below with respect to FIGS. 5A and 5B .

[0021] 2, the set of temperature sensors 202 includes six temperature sensors 202a, 202b, 202c, 202d, 202e, and 202f. Temperature sensor 202a is positioned downstream from magma well 300 (e.g., near the outlet of magma well 300) to measure the temperature of heated molten salt 318b exiting magma well 300. Temperature sensor 202b is positioned upstream from heat exchanger 102 (e.g., near the inlet of heat exchanger 102) to measure the temperature of heated molten salt 318b before it undergoes heat exchange with working fluid 104. Temperature sensor 202c is positioned downstream from heat exchanger 102 (e.g., near the outlet of heat exchanger 102) to measure the temperature of cooled molten salt 318a after it has undergone heat exchange with working fluid 104. Temperature sensor 202d is positioned upstream from magma well 300 (e.g., proximate the entrance to magma well 300) and measures the temperature of cooled molten salt 318a before it enters magma well 300. Temperature sensor 202e is coupled to fluid conduit 204 on the inlet side of heat exchanger 104 (e.g., near the inlet of heat exchanger 102) and measures the temperature of working fluid 104a before it enters heat exchanger 102. Temperature sensor 202f is coupled to fluid conduit 204 on the outlet side of heat exchanger 104 (e.g., near the outlet of heat exchanger 102) and measures the temperature of working fluid 104b after it exits heat exchanger 102.

[0022] Each set of temperature sensors 202 can be coupled to a computing device 700 (see FIG. 7 ) that can use temperature data collected by the set of temperature sensors 202 to control the flow of molten salt 318 throughout system 200. Computing device 700 can generate one or more control signals based on an analysis of the temperature data from one or more of sensors 202 and control the flow of molten salt 318 by sending the control signals to one or more of pumps 112 a, 112 b, and 112 c of system 200. For example, one control signal can be based on a temperature difference using measurements obtained from temperature sensor 202 d and temperature sensor 202 a (e.g., the temperature difference across magma well 300). The control signal can then be sent to pump 112 a to control the flow of molten salt 318 through magma well 300. For example, if the temperature difference between heated molten salt 318b leaving magma well 300 (measured by sensor 202a) and cooled molten salt 318a entering magma well 300 (measured by sensor 202d) is less than a target or threshold value, the control signal may cause pump 112a to decrease the flow rate of molten salt 318a into magma well 300. This will increase the residence time of molten salt 318b within magma well 300, and as a result, heated molten salt 318b will have an increased temperature. Conversely, if the difference in temperature between the heated molten salt 318b leaving the magma well 300 (measured by sensor 202a) and the cooled molten salt 318a entering the magma well 300 (measured by sensor 202d) is greater than a target value or threshold, the control signal may cause the pump 112a to increase the flow rate of the molten salt 318a into the magma well 300, thereby decreasing the residence time within the magma well 300 and decreasing the temperature of the heated molten salt 318b.

[0023] An additional or alternative control signal can be determined based on the temperature difference using measurements obtained from temperature sensor 202b and temperature sensor 202c (e.g., the temperature difference of the molten salt 318 across the heat exchanger 102). This control signal can be sent to pump 112b to control the flow rate of the heated molten salt 318b through the heat exchanger 102. For example, if the temperature difference between the heated molten salt 318b entering the heat exchanger 102 (measured by sensor 202b) and the cooled molten salt 318a exiting the heat exchanger 102 (measured by sensor 202c) is less than a target or threshold value, the control signal can direct pump 112b to decrease the flow rate of the molten salt 318b into the heat exchanger 102. This can increase the residence time of the molten salt 318b within the heat exchanger 102, resulting in additional heat exchange and cooling the molten salt 318b to form cooled molten salt 318a. Conversely, if the temperature difference between the heated molten salt 318b entering the heat exchanger 102 (measured by sensor 202b) and the cooled molten salt 318a exiting the heat exchanger 102 (measured by sensor 202c) is greater than a target value or threshold, the control signal may cause the pump 112b to increase the flow rate of the molten salt 318b into the heat exchanger 102, thereby decreasing the residence time within the heat exchanger 102 and increasing the temperature of the cooled molten salt 318a exiting the heat exchanger 102.

[0024] Another additional or alternative control signal may be based on a temperature difference using measurements obtained from temperature sensors 202e and 202f (e.g., the temperature difference of the working fluid 104 across the heat exchanger 102). This control signal may be sent to pump 112c for controlling the flow rate of the working fluid 104 through the heat exchanger 102. Similar to the description above for pumps 112a and 112b, a control signal may be provided to pump 112c to adjust the flow rate of the working fluid 104a through the heat exchanger 102, for example, to achieve a target temperature difference between the working fluid 104a entering the heat exchanger 102 and the working fluid 104b exiting the heat exchanger 102.

[0025] In some cases, the control signal can be based on a temperature setpoint and a temperature differential based on the measured temperature value. For example, the measured temperature from sensors 202a-f may be compared to a predefined setpoint, and / or the temperature differential may be compared to a predefined setpoint (e.g., as described above) to determine a control signal for adjusting the flow rate provided by one or more of pumps 112a-c.

[0026] The control signal generated by the computing device 700 may be based on or modified by any one or more of the following control approaches: proportional control, integral control, and derivative response control. Proportional control is a type of linear feedback control system that applies a correction to a controlled variable. The size of the correction is proportional to an error signal that accounts for the difference between the setpoint and the measured value. In a non-limiting embodiment, the setpoint can be based on a measured temperature, such as the temperature difference across the heat exchanger 102, and the controlled variable can be, for example, the pump motor speed or the flow rate of the molten salt 318. Because proportional control is based on the difference between the setpoint and the measured value, an offset error is inevitable. Integral response control can reduce and / or eliminate the offset error by taking into account the amount of time the offset error has existed. Derivative response control uses the rate of change of the error to generate a damping signal that minimizes overshoot and oscillations around the setpoint.

[0027] 3 is a schematic diagram of a cross-sectional view of a magma well 300 according to an example embodiment. Magma well 300 is configured to operate as a heat exchanger in which magma 302 within magma body 304 serves as a heat source for heating molten salt 318 transported through magma well 300.

[0028] Magma well 300 is formed from a borehole 306 that extends from a surface 310 at least partially into a magma body 304 containing magma 302. Borehole 306 may be partially or completely lined with a casing 308 and extends from surface 310 through a magma ceiling 312 separating rock layers 314 into magma body 304 storing magma 302.

[0029] Contained within the magma well 300 is a length of pipe, e.g., a segment of fluid conduit 108, at least partially submerged in magma 302. The portion of the fluid conduit 108 passing through rock formation 314 may be encased in an insulating layer 316 to reduce undesired heat loss / transfer from the molten salt 318 passing therethrough. A more detailed view of the top of the magma well 300 is shown in FIG. 4A and continues in the following figures. Although not depicted in FIG. 3, the portion of the fluid conduit 108 outside the magma well 300 may also be encased in an insulating layer, as shown in FIG. 5A.

[0030] During operation of magma well 300, cooled molten salt 318a enters magma well 300 and travels downward from surface 310 toward magma body 304, absorbing heat from magma 302 to form heated molten salt 318b. Heated molten salt 318b can be removed from magma well 300 and transported through a system, such as system 100 or system 200, which can utilize heated molten salt 318b as described above. While heat exchange within magma well 300 is shown as occurring through segments of fluid conduits 108 submerged within magma 302, in another embodiment, heat exchange can instead occur within a submerged vessel that is at least partially submerged within magma 302 and fluidly coupled with a set of fluid conduits 108, allowing cooled molten salt 318a to enter the vessel and heated molten salt 318b to exit the vessel.

[0031] The magma well 300 may be prepared using any suitable method. For example, during drilling of the borehole 306, a sufficient amount of drilling fluid with desired thermodynamic properties can solidify the magma 302 ahead of the drill bit, allowing the drill bit to drill the borehole 306 into the magma body 304 until the desired depth is achieved. The solidified magma 302 can be maintained by a continuous inflow of drilling fluid into the borehole 306. A length of fluid conduit 108 can be installed within the borehole 306 while it is in a solidified form, either while drilling fluid is maintained within the borehole 306, or immediately after the drilling fluid is withdrawn. Over time, the sidewalls of the borehole 306 within the magma body 304 will remelt and reform around the outer sidewalls of the segment of fluid conduit 108 suspended within the magma body 304. Thus, borehole 306 collapses from its excavated configuration, represented by dashed line 322, allowing magma 302 to solidify against fluid conduit 108. A more detailed view of the reformed layered rock around fluid conduit 108 is shown in Figure 4B below.

[0032] 4A and 4B are schematic diagrams of the upper and lower portions, respectively, of a magma well 300, according to an illustrative embodiment. With particular reference to FIG. 4A, cooled molten salt 318a flows in a downward direction in a fluid conduit 108 contained within a borehole 306 extending from the surface through a rock formation 314. The fluid conduit 108 is shown encased in an insulating layer 316 to reduce heat loss / transfer. Heated molten salt 318b is returned to the surface via the fluid conduit 108 passing through the rock formation 314.

[0033] 4B depicts the formation of layered rock around the fluid conduit 108 after the borehole 306 collapses. In particular, the magma 302 may melt the sidewalls of the borehole 306, bringing the magma 302 into contact with the exterior surface of the fluid conduit 108. Heat transfer from the magma 302 to the molten salt 318 flowing through the fluid conduit 108 may cause the magma 302 to solidify against the fluid conduit 108, forming a solid phase 402. The solid phase rock layer 402 may be separated from the magma 302 by a plastic rock layer 404.

[0034] 5A and 5B are schematic diagrams depicting the placement of temperature sensors, according to various exemplary embodiments. Temperature sensors 502 and 504 in FIG. 5 can be used as temperature sensor 202 shown in FIG. 2 , configured to measure the temperature of fluid flowing through fluid conduit 108. In particular, FIG. 5A shows a surface temperature sensor 502 coupled to the outer surface of fluid conduit 108 and capable of collecting temperature data usable to calculate the temperature of molten salt 318 flowing through the illustrated segment of fluid conduit 108. A computing device can calculate the temperature of molten salt 318 based on the temperature at the surface of fluid conduit 108 and the thermal conductivity of fluid conduit 108.

[0035] 5B depicts an immersed temperature sensor 504 passing through the sidewall of a fluid conduit to measure the temperature of the fluid flowing through the fluid conduit. In a non-limiting example, the immersed temperature sensor 504 is used to measure the temperature of a gaseous fluid, such as steam 506 or other gaseous working fluid. The immersed temperature sensor 504 may also be used to measure the temperature of a liquid that does not exceed the operating temperature of the immersed temperature sensor 504, such as a condensed working fluid 508. For example, the immersed temperature sensor 504 may be used to measure the temperature of the working fluid condensate 104a entering the heat exchanger 102 and / or the working gas 104b exiting the heat exchanger 102. The temperature data obtained by measurements from these temperature sensors 502, 504 is used by a computing device, such as computing device 700, to control a pump that controls the flow rate of the working fluid through the heat exchanger 102, i.e., to slow the flow rate to increase the heat transfer rate or to speed up the flow rate to decrease the heat transfer rate, or to control pump 112, which controls the flow rate of the molten salt 318 in such a way that the heat transfer rate with the working fluid can be varied.

[0036] 6 is a schematic diagram of a networked system for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger according to an example embodiment. System 600 includes multiple computing devices 602, 604, and 606. Examples of computing devices 602, 604, and 606 may include servers, desktop computers, laptop computers, tablets, mobile phones, or any other form of computing device. Generally, one or more of the computing devices may be used to send and receive data for controlling the flow of molten salt through a system including a magma-driven heat exchanger.

[0037] In a non-limiting example, the computing device 602 may be a server that receives temperature data from the set of temperature sensors 202 and generates control signals for transmission to the set of pumps 112 that control the flow of the molten salt 318. In some embodiments, the computing device 602 may receive temperature data directly from the set of temperature sensors 202 via a direct communication link 610 and may transmit control signals directly to the set of pumps 112 via a direct communication link 612. The direct communication links 610 and 612 may be hardwired communication links or wireless communication links that implement a device-to-device communication protocol. In another embodiment, the temperature data may be transmitted from the set of temperature sensors 202 to the computing device 602 via a network 608, and the control signals may be transmitted from the computing device 602 to the set of pumps 112 via the network 608. The network 608 may include the Internet, a public switched telephone network (PSTN), a cellular network, a private network, etc.

[0038] An operator of computing device 604 and / or 606 can receive system alerts and can monitor the operation of computing device 602, temperature data collected by the set of temperature sensors 202, or operating parameters of the set of pumps 112. In some embodiments, an override command can be generated by one of computing devices 604 or 606 to control the flow of molten salt.

[0039] 7 is a schematic diagram of an apparatus for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger according to an example embodiment. Apparatus 700 may be a computing device such as computing device 602 of FIG. 6. Apparatus 700 includes a bus system 702 supporting communication between at least one processor 704, at least one storage device 714, at least one communication interface 708, and at least one input / output (I / O) device 710.

[0040] Memory 706 and persistent storage 712 are examples of storage 714, which represents any structure capable of storing and facilitating retrieval of information (such as data, program code, and / or other suitable information on a temporary or permanent basis). Memory 706 may represent random access memory or any other suitable volatile or non-volatile storage device. Persistent storage 712 may include one or more components or devices that support long-term retention of data, such as read-only memory, a hard drive, a flash memory, or an optical disk.

[0041] Processor 704 may execute instructions 713, which may be stored in persistent storage 712 and loaded into memory 706. Processor 704 may include any suitable number and type of processors or other devices in any suitable arrangement. Example types of processor 704 include microprocessors, microcontrollers, digital signal processors, field programmable gate arrays, application specific integrated circuits, and discrete circuits.

[0042] The communication interface 708 may support communication with other systems or devices. For example, the communication interface 708 may include a network interface card or a wireless transceiver to facilitate communication over the network 608. The communication interface 708 may support communication via any suitable physical or wireless communication link. The communication interface 708 enables the device 700 to communicate with the temperature sensor 202 and the pump 112 directly via a device-to-device communication protocol or via the network 608.

[0043] The input / output device 710 may allow for the input and output of data. For example, the input / output device 710 may provide a connection for user input through a keyboard, mouse, keypad, touch screen, or other suitable input device. The input / output device 710 may also send output to a display, printer, or other appropriate output device.

[0044] As described herein, apparatus 700 can be used to control the flow of molten salt fluid through a system, such as system 100 or system 200, based on temperature data obtained from temperature sensor 202. Apparatus 700 can generate a control signal based on the temperature data for transmission to pump 112, which can be used to control the flow of molten salt fluid.

[0045] 8 is a flowchart of a process for controlling the flow of molten salt through a system implementing a magma-driven heat exchanger according to an example embodiment. Flowchart 800 may be implemented on a computing device, such as computing device 602 or computing device 700.

[0046] Flowchart 800 begins at step 802 by obtaining first temperature data of heated molten salt transported from a magma-driven heat exchanger extending at least partially within a magma body containing magma. The molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma and forms heated molten salt. For example, temperature data from sensors 202a and / or 202b of FIG. 2 can be used to determine the temperature of heated molten salt 318b.

[0047] In step 804, second temperature data of the cooled molten salt delivered from a second heat exchanger disposed external to the magma-driven heat exchanger is obtained. The second heat exchanger converts the heated molten salt to cooled molten salt by heating the working fluid from the first temperature to a second temperature higher than the first temperature. For example, temperature data from sensors 202c and / or 202d in FIG. 2 can be used to determine the temperature of cooled molten salt 318a.

[0048] In step 806, control signals are generated for controlling one or more fluid control devices based on at least one of the first temperature data or the second temperature data. The control signals may be generated by using one or more of a proportional control approach, an integral control approach, and a derivative response control approach. Examples of control signals that may be generated and transmitted to pumps 112a-c are described above with respect to the example of FIG. 2.

[0049] [Additional Embodiments]

[0050] The following descriptive embodiments are provided to further support one or more aspects of the present invention.

[0051] In a first embodiment, aspects of the present invention are directed to a system for controlling the flow of molten salt through a magma-driven heat exchanger. The system includes a magma-driven heat exchanger extending at least partially within a magma body containing magma. The molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form heated molten salt. A second heat exchanger disposed external to the magma-driven heat exchanger uses the heated molten salt to heat a working fluid from a first temperature to a second temperature higher than the first temperature. The system also includes a set of fluid conduits defining a flow path that transports the molten salt in a loop between the magma-driven heat exchanger and the second heat exchanger.

[0052] In another aspect of the first embodiment, the fluid control device includes a set of pumps operably connected to a set of fluid conduits. The set of pumps is configured to control a flow rate of molten salt along a flow path. The system further includes a set of temperature sensors coupled to the set of fluid conduits. The set of temperature sensors is configured to determine a temperature of the molten salt at a predetermined location along the flow path, and a computing device is operably connected to the set of pumps and the set of temperature sensors, and the computing device controls operation of the set of pumps based on temperature data obtained by the set of temperature sensors.

[0053] In another aspect of the first embodiment, the computing device further includes a memory storing instructions and a processor communicatively coupled to the memory, the processor executing instructions to determine a first temperature of the heated molten salt at a first flow location and a second temperature of the cooled molten salt at a second flow location, and generate control signals to control the set of pumps based on a temperature difference based on at least one of the first temperature and the second temperature.

[0054] In another aspect of the first embodiment, the control signal is generated using at least one of a proportional response approach based on deviation from the temperature set point and temperature differential, an integral response approach based on the length of time of deviation from the temperature set point, and a derivative response approach that reduces oscillations about the set point based on the rate of change of deviation from the temperature set point.

[0055] In another aspect of the first embodiment, at least one temperature sensor in the set of temperature sensors is coupled to an exterior surface of the set of fluid conduits.

[0056] In another aspect of the first embodiment, the system includes a second set of fluid conduits that convey the molten salt to and from the second heat exchanger, a second set of temperature sensors coupled to the second set of fluid conduits, and a second set of pumps operably connected to the second set of fluid conduits, wherein the computing device controls the second set of pumps based on temperature data from the second set of temperature sensors, and the second set of temperature sensors extend into the second set of fluid conduits and contact the molten salt therein.

[0057] In another aspect of the first embodiment, the system includes a hot tank disposed in a flow path receiving heated molten salt from the magma-driven heat exchanger, and a cold tank disposed in a flow path receiving cooled molten salt from the second heat exchanger.

[0058] In another aspect of the first embodiment, the system includes a third set of fluid conduits that carry a working fluid to and from the second heat exchanger. The system also includes a third set of temperature sensors coupled to the third set of fluid conduits. The system also includes a third set of pumps operably connected to the third set of fluid conduits, and the computing device controls the third set of pumps based on temperature data from the third set of temperature sensors.

[0059] In a second embodiment, aspects of the present invention are directed to an apparatus for controlling the flow of molten salt through a magma-driven heat exchanger. The apparatus includes a memory storing instructions and a processor communicatively coupled to the memory. The processor is configured to execute the instructions to obtain first temperature data of heated molten salt transported from a magma-driven heat exchanger extending at least partially within a magma body containing magma. The molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form heated molten salt. The processor is also configured to execute the instructions to obtain second temperature data of cooled molten salt transported from a second heat exchanger disposed external to the magma-driven heat exchanger. The second heat exchanger converts the heated molten salt to cooled molten salt by heating the working fluid from a first temperature to a second temperature higher than the first temperature. The processor is also configured to execute the instructions and generate control signals to control operation of one or more fluid control devices configured to control the flow of molten salt based on at least one of the first temperature data and the second temperature data.

[0060] In another aspect of the second embodiment, the first temperature data is measured by a first temperature sensor positioned on an outer surface of a fluid conduit carrying heated molten salt from the magma-driven heat exchanger, and the second temperature data is measured by a second temperature sensor positioned on an outer surface of a fluid conduit carrying cooled molten salt to the magma-driven heat exchanger.

[0061] In another aspect of the second embodiment, the one or more fluid control devices include at least one pump.

[0062] In another aspect of the second embodiment, the at least one pump is a variable frequency drive pump.

[0063] In another aspect of the second embodiment, the apparatus further includes a communication interface communicatively connected to the first temperature sensor, the second temperature sensor, and the at least one pump.

[0064] In another aspect of the second embodiment, the processor executes the instructions to generate the control signal using at least one of a proportional control approach, an integral control approach, and a differential response control approach.

[0065] In another aspect of the second embodiment, the processor executes instructions to obtain temperature data of the working fluid flowing through the second heat exchanger and generate a second control signal for controlling the flow rate of the working fluid through the second heat exchanger, which second control signal is transmitted to one or more fluid control devices connected to a fluid conduit carrying the working fluid.

[0066] In a third embodiment, aspects of the present invention are directed to a method for controlling the flow of molten salt through a magma-driven heat exchanger. The method includes obtaining first temperature data of heated molten salt transported from a magma-driven heat exchanger extending at least partially within a magma body containing magma. The molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form heated molten salt. The method also includes obtaining second temperature data of cooled molten salt transported from a second heat exchanger disposed external to the magma-driven heat exchanger. The second heat exchanger converts the heated molten salt to cooled molten salt by heating the working fluid from a first temperature to a second temperature higher than the first temperature. The method also includes generating control signals for controlling operation of one or more fluid control devices configured to control the flow rate of the molten salt based on at least one of the first temperature data and the second temperature data.

[0067] In another aspect of the third embodiment, the first temperature data and the second temperature data are received from temperature sensors disposed on an exterior surface of a fluid conduit through which the heated or cooled molten salt flows.

[0068] In another aspect of the third embodiment, the control signal is generated using at least one of a proportional response approach based on deviation from the temperature set point and temperature differential, an integral response approach based on the length of time of deviation from the temperature set point, and a derivative response approach that reduces oscillations about the set point based on the rate of change of deviation from the temperature set point.

[0069] In another aspect of the third embodiment, the control signal causes the one or more fluid control devices to vary the flow rate of the molten salt based on the temperature difference across the magma-driven heat exchanger or the second heat exchanger.

[0070] In another aspect of the third embodiment, the control signal causes one or more fluid control devices to modify the flow rate of the molten salt based on a deviation of the measured temperature from a set temperature.

[0071] In another aspect of the third embodiment, the control signal causes the one or more fluid control devices to vary only the flow rate of the molten salt through the magma-driven heat exchanger or the second heat exchanger.

[0072] Although embodiments of the present invention have been described with reference to several elements, any elements described in the embodiments described herein are exemplary and may be omitted, substituted, added, combined, or rearranged as applicable to form new embodiments. Those skilled in the art will recognize, upon reading this specification, that such additional embodiments are effectively disclosed herein. For example, if the present invention describes a property, structure, size, shape, arrangement, or configuration of an element or a process for making or using the element or combination of elements, that property, structure, size, shape, arrangement, or configuration can also be incorporated into any other element or combination of elements, or into a process for making or using the element or combination of elements described herein, to provide further embodiments.

[0073] Additionally, where embodiments are described herein as including some element or group of elements, further embodiments can consist essentially of or consist of the element or group of elements. Also, although the open-ended term "comprising" is commonly used herein, further embodiments can be formed by substituting the terms "consisting essentially of" or "consisting of."

[0074] While the present invention has been particularly shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. The inventors expect that those skilled in the art will adopt such variations as appropriate, and the inventors intend that the invention be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Furthermore, any combination of the above-described elements in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

1. 1. A system for controlling a flow of molten salt through a magma-driven heat exchanger, the system comprising: a magma-driven heat exchanger extending at least partially within a magma body containing magma, wherein molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form heated molten salt; a second heat exchanger disposed external to the magma-driven heat exchanger, the second heat exchanger using the heated molten salt to heat a working fluid from a first temperature to a second temperature higher than the first temperature; a set of fluid conduits forming a flow path for transporting the molten salt in a loop between the magma-driven heat exchanger and the second heat exchanger; a fluid control device configured to control the flow of the molten salt through the flow path.

2. The fluid control device includes a set of pumps operably connected to the set of fluid conduits, the set of pumps configured to control a flow rate of the molten salt along the flow paths, and the system further includes: a set of temperature sensors coupled to the set of fluid conduits, the set of temperature sensors configured to determine a temperature of the molten salt at a predetermined location along the flow path; and 10. The system of claim 1, comprising: a computing device operably connected to the set of pumps and the set of temperature sensors, the computing device configured to control operation of the set of pumps based on temperature data obtained by the set of temperature sensors.

3. The computing device further comprises: a memory unit that stores instructions; a processor communicatively coupled to the memory; The processor: determining a first temperature of the heated molten salt at a first flow location and a second temperature of the cooled molten salt at a second flow location; The system of claim 2 , executing the instructions to generate a control signal for controlling the set of pumps based on a temperature difference based on at least one of the first temperature and the second temperature.

4. 4. The system of claim 3, wherein the control signal is generated using at least one of a proportional response approach based on deviation from a temperature set point and a temperature difference, an integral response approach based on the length of time of deviation from the temperature set point, and a derivative response approach that reduces oscillations about the temperature set point based on the rate of change of deviation from the temperature set point.

5. The system of claim 2 , wherein at least one temperature sensor in the set of temperature sensors is coupled to an exterior surface of the set of fluid conduits.

6. The system further comprises: a second set of fluid conduits for carrying the molten salt to and from a second heat exchanger; a second set of temperature sensors connected to the second set of fluid conduits; a second set of pumps operably connected to the second set of fluid conduits; the computing device controls the second set of pumps based on temperature data from the second set of temperature sensors; The system of claim 2 , wherein the second set of temperature sensors extend into the second set of fluid conduits and contact the molten salt therein.

7. a high temperature tank disposed in the flow path to receive heated molten salt from the magma-driven heat exchanger; 10. The system of claim 1, further comprising: a cryogenic tank disposed in the flow path to receive cooled molten salt from the second heat exchanger.

8. The system further comprises: a third set of fluid conduits carrying working fluid to and from the second heat exchanger; a third set of temperature sensors coupled to the third set of fluid conduits; a third set of pumps operably connected to the third set of fluid conduits; The system of claim 2 , wherein the computing device controls the third set of pumps based on temperature data from the third set of temperature sensors.

9. 1. An apparatus for controlling the flow of molten salt through a magma-driven heat exchanger, the apparatus comprising: a memory unit that stores instructions; a processor communicatively coupled to the memory; The processor: obtaining first temperature data of heated molten salt conveyed from a magma-driven heat exchanger extending at least partially into a magma body containing magma, wherein the molten salt flowing through the magma-driven heat exchanger absorbs heat from the magma to form the heated molten salt; acquiring second temperature data of the cooled molten salt delivered from a second heat exchanger disposed outside the magma-driven heat exchanger, the second heat exchanger converting the heated molten salt into the cooled molten salt by heating a working fluid from a first temperature to a second temperature higher than the first temperature; an apparatus configured to execute instructions to generate control signals configured to control operation of one or more fluid control devices configured to control a flow rate of the molten salt based on at least one of the first temperature data and the second temperature data.

10. 10. The apparatus of claim 9, wherein the first temperature data is measured by a first temperature sensor disposed on an outer surface of a fluid conduit carrying the heated molten salt from the magma-driven heat exchanger, and the second temperature data is measured by a second temperature sensor disposed on an outer surface of a fluid conduit carrying the cooled molten salt to the magma-driven heat exchanger.

11. The apparatus of claim 9 , wherein the one or more fluid control devices include at least one pump.

12. The apparatus of claim 11 , wherein the apparatus further comprises a communication interface communicatively coupled to a first temperature sensor, a second temperature sensor, and the at least one pump.

13. The apparatus of claim 9 , wherein the processor executes the instructions to generate the control signal using at least one of a proportional control approach, an integral control approach, and a derivative response control approach.

14. The processor: acquiring temperature data of the working fluid flowing through the second heat exchanger; 10. The apparatus of claim 9, wherein the instructions execute: generating a second control signal for controlling a flow rate of the working fluid through the second heat exchanger, the second control signal being transmitted to one or more fluid control devices connected to a fluid conduit carrying the working fluid.

15. 1. A method for controlling the flow of molten salt through a magma-driven heat exchanger, the method comprising: obtaining first temperature data of heated molten salt conveyed from a magma-driven heat exchanger extending at least partially into a magma body containing magma, the molten salt flowing through the magma-driven heat exchanger absorbing heat from the magma to form the heated molten salt; acquiring second temperature data of the cooled molten salt delivered from a second heat exchanger located external to the magma-driven heat exchanger, the second heat exchanger converting the heated molten salt into the cooled molten salt by heating a working fluid from a first temperature to a second temperature higher than the first temperature; generating control signals to control operation of one or more fluid control devices configured to control a flow rate of the molten salt based on at least one of the first temperature data and the second temperature data.

16. 16. The method of claim 15, wherein the first temperature data and the second temperature data are received from temperature sensors disposed on an exterior surface of a fluid conduit through which the heated or cooled molten salt flows.

17. 16. The method of claim 15, wherein the control signal is generated using at least one of a proportional response approach based on deviation from a temperature set point and a temperature difference, an integral response approach based on the length of time of deviation from the temperature set point, and a derivative response approach that reduces oscillations about the temperature set point based on the rate of change of deviation from the temperature set point.

18. 16. The method of claim 15, wherein the control signal causes the one or more fluid control devices to modify the flow rate of the molten salt based on a temperature difference across the magma-driven heat exchanger or the second heat exchanger.

19. 16. The method of claim 15, wherein the control signal causes the one or more fluid control devices to modify the flow rate of the molten salt based on a deviation of a measured temperature from a set temperature.

20. 16. The method of claim 15, wherein the control signal causes the one or more fluid control devices to modify only the flow rate of the molten salt through the magma-driven heat exchanger or the second heat exchanger.

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