Device and method for heating molten salt

Abstract

The present invention relates to a device and method for heating molten salt. The device comprises: a first salt liquid tank, which is provided with at least one preheater; a second salt liquid tank, which is arranged at a higher position than the first salt liquid tank; at least one group of molten salt electrodes, each group of molten salt electrodes includes a plurality of molten salt electrode boxes, and the plurality of molten salt electrode boxes are arranged at a position higher than the first salt liquid tank and lower than the second salt liquid tank; at least one group of electrode inlet insulation pipes; at least one group of electrode outlet insulation pipes; a power supply device, each phase of the multi-phase alternating current of the power supply device is electrically connected to a corresponding molten salt electrode box in the plurality of molten salt electrode boxes; a first connecting pipe, which connects the first salt liquid tank fluid to the second salt liquid tank; a molten salt circulation pump, which is arranged in the first connecting pipe; and a controller, which is electrically connected to the preheater, the power supply device and the molten salt circulation pump to control the opening or closing of the preheater, the power supply or power off of the power supply device and the rotation speed of the molten salt circulation pump.

Description

Technical Field

[0001] The present invention relates to the field of molten salt heating, and more particularly to a device and method for heating molten salt using electrodes. Background Art

[0002] Molten salt is a heat transfer and heat storage medium with extremely good fluidity. It has the characteristics of low vapor pressure, wide applicable temperature range, stable chemical properties, large heat capacity, non-combustibility, low cost and easy preparation. It has broad application prospects in the field of heat storage, especially in the field of medium and high temperature heat storage.

[0003] At present, molten salt electric heating mostly adopts indirect heating by heat conduction using electric heating rods. The higher the working temperature of the heating wire, the shorter the service life. The better the insulation between the heating wire and the outer sleeve, the worse the heat transfer. Therefore, it is not conducive to the application of high-temperature and high-power electric heating of molten salt.

[0004] The electrode heating method is that electric current directly passes through molten salt to generate heat. The molten salt itself is a heating element, and there is no problem caused by indirect heating. However, due to the high electrical conductivity of molten salt, previous electrode heating technical means cannot control the current density on the electrode surface within a reasonable range, and it is difficult to avoid corrosion of the electrode material and electrolysis of the molten salt.

[0005] The information disclosed in this Background of the Invention section is only intended to enhance understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a device and method for heating molten salt using electrodes. The present invention can successfully solve the technical problem of realizing low current density operation of electrodes in various ion conductors at any voltage, and is not only applicable to electrode heating of molten salt, but also to electrode heating of other ion conductors with fluidity. By using the present invention, molten salt electric heating equipment of various power sizes suitable for various voltage ranges can be designed and manufactured.

[0007] To achieve the above-mentioned object, the present invention provides a device for heating molten salt, which comprises: a first salt solution tank, in which at least one preheater is arranged; a second salt solution tank, which is arranged at a higher position than the first salt solution tank; at least one group of molten salt electrodes, each group of molten salt electrodes includes a plurality of molten salt electrode boxes, and the plurality of molten salt electrode boxes are arranged at a position higher than the first salt solution tank and lower than the second salt solution tank; at least one group of electrode inlet insulation pipes, the number of pipes in each group of electrode inlet insulation pipes is the same as the number of a plurality of molten salt electrode boxes in each group of molten salt electrodes, the first end of the electrode inlet insulation pipe is fluidically connected to the second salt solution tank, and the second end of the electrode inlet insulation pipe is fluidically connected to a corresponding one of the plurality of molten salt electrode boxes, so that the molten salt can flow through the electrode inlet insulation pipe; at least one group of electrode outlet insulation pipes, the number of pipes in each group of electrode outlet insulation pipes is the same as the number of a plurality of molten salt electrode boxes in each group of molten salt electrodes. the same number of molten salt electrode boxes, the first end of the outlet electrode insulating pipe is fluidly connected to a corresponding one of the multiple molten salt electrode boxes, and the second end of the outlet electrode insulating pipe is fluidly connected to the first salt liquid tank, so that molten salt can flow through the outlet electrode insulating pipe; a power supply device, which includes a multi-phase alternating current and the number of phases of the multi-phase alternating current is the same as the number of the multiple molten salt electrode boxes, and each phase of the multi-phase alternating current of the power supply device is electrically connected to a corresponding one of the multiple molten salt electrode boxes; a first connecting pipe, which connects the first salt liquid tank fluid to the second salt liquid tank; a molten salt circulation pump, which is arranged in the first connecting pipe and is used to pump the molten salt in the first salt liquid tank to the second salt liquid tank; and a controller, which is electrically connected to the preheater, the power supply device and the molten salt circulation pump to control the opening or closing of the preheater, the power supply or power off of the power supply device and the speed of the molten salt circulation pump.

[0008] In the above-mentioned device for heating molten salt, each group of molten salt electrodes has three molten salt electrode boxes, the multi-phase alternating current is three-phase alternating current, each group of inlet electrode insulating pipes includes three inlet electrode insulating pipes, and each group of outlet electrode insulating pipes includes three outlet electrode insulating pipes.

[0009] In the above-mentioned device for heating molten salt, the molten salt flowing in each pipe in each group of inlet electrode insulating pipes generates a first resistance value resistor with the same resistance value, and the molten salt flowing in each pipe in each group of outlet electrode insulating pipes generates a second resistance value resistor with the same resistance value.

[0010] Furthermore, the first resistance value and the second resistance value are also the same.

[0011] In the above-mentioned device for heating molten salt, the molten salt electrode box is made of corrosion-resistant and high-temperature resistant metal material to form a container with a specific inner surface area, and has an electrode inlet insulating pipe connection port and an electrode outlet insulating pipe connection port, the second end of the electrode inlet insulating pipe is fluidically connected to the electrode inlet insulating pipe connection port of the corresponding molten salt electrode box, and the first end of the electrode outlet insulating pipe is fluidically connected to the electrode outlet insulating pipe connection port of the corresponding molten salt electrode box; and a conductive copper bus is connected to the outer wall of the molten salt electrode box.

[0012] In the above-mentioned device for heating molten salt, the inlet electrode insulating pipe and the outlet electrode insulating pipe are formed in the form of a "tube" or a "trough"; the inlet electrode insulating pipe is inclined at a specific angle to the horizontal plane, and the angles of each pipe in each group of inlet electrode insulating pipes relative to the horizontal plane are the same, the lengths of each pipe in each group of inlet electrode insulating pipes are the same, and the flow cross-sectional areas of each pipe in each group of inlet electrode insulating pipes are the same, so as to ensure that the flow rates of each pipe in each group of inlet electrode insulating pipes are the same; the outlet electrode insulating pipe is inclined at a specific angle to the horizontal plane, and the angles of each pipe in each group of outlet electrode insulating pipes relative to the horizontal plane are the same, the lengths of each pipe in each group of outlet electrode insulating pipes are the same, and the flow cross-sectional areas of each pipe in each group of outlet electrode insulating pipes are the same, so as to ensure that the flow rates of each pipe in each group of outlet electrode insulating pipes are the same.

[0013] According to the device for heating molten salt of the present invention, it is further provided with: a molten salt storage tank, which has a volume greater than that of the first salt liquid tank, and a plurality of preheaters are arranged inside the molten salt storage tank; a second connecting pipe, which connects the first salt liquid tank fluid to the molten salt storage tank; a molten salt return pump, which is arranged in the second connecting pipe and is used to pump the molten salt in the first salt liquid tank to the molten salt storage tank; a third connecting pipe, which connects the molten salt storage tank fluid to the second salt liquid tank; and a flow control valve, which is arranged in the third connecting pipe; wherein the controller is further electrically connected to the plurality of preheaters in the molten salt storage tank, the molten salt return pump and the flow control valve to control the opening or closing of the plurality of preheaters in the molten salt storage tank, the rotation speed of the molten salt return pump and the opening of the flow control valve.

[0014] The present invention further provides a method for heating molten salt, which uses the above-mentioned device for heating molten salt, and the method comprises the following steps: using a preheater to heat the salt in the first salt liquid tank, and heating the salt to a molten state capable of flowing; after the salt is in a molten state capable of flowing, closing the preheater; using a molten salt circulation pump to pump the molten salt in the first salt liquid tank to a second salt liquid tank, and controlling the rotation speed of the molten salt circulation pump so that the amount of molten salt entering the second salt liquid tank is greater than the amount of molten salt flowing out of the second salt liquid tank through the inlet electrode insulating pipe; after the molten salt flowing through the inlet electrode insulating pipe enters the molten salt electrode box and correspondingly flows into the first salt liquid tank through the outlet electrode insulating pipe, turning on a power supply device to supply power, thereby heating the molten salt; when the molten salt in the second salt liquid tank reaches a predetermined liquid level, controlling the rotation speed of the molten salt circulation pump so that the amount of molten salt entering the second salt liquid tank is equal to the amount of molten salt flowing out of the second salt liquid tank through the inlet electrode insulating pipe.

[0015] In the above method, when the heating is about to end, the rotation speed of the molten salt circulation pump is controlled so that the amount of molten salt entering the second salt solution tank is less than the amount of molten salt flowing out of the second salt solution tank through the electrode inlet insulation pipe.

[0016] The present invention also provides a method for heating molten salt, which uses the above-mentioned device for heating molten salt, and the method comprises the following steps: using a preheater to heat the salt in the first salt liquid tank and / or the molten salt storage tank, and heating the salt to a molten state capable of flowing; after the salt is in a molten state capable of flowing, closing the preheater; adjusting the flow control valve so that the molten salt in the molten salt storage tank flows into the second salt liquid tank, and controlling the opening of the flow control valve so that the amount of molten salt entering the second salt liquid tank is greater than the amount of molten salt flowing out of the second salt liquid tank through the inlet electrode insulating pipe; waiting for the flow control valve to open, and then closing the preheater; adjusting the flow control valve so that the molten salt in the molten salt storage tank flows into the second salt liquid tank, and controlling the opening of the flow control valve so that the amount of molten salt entering the second salt liquid tank is greater than the amount of molten salt flowing out of the second salt liquid tank through the inlet electrode insulating pipe; and After the molten salt flowing through the inlet electrode insulating pipe enters the molten salt electrode box and correspondingly flows into the first salt liquid tank through the outlet electrode insulating pipe, the power supply device is turned on to supply power, thereby heating the molten salt; the molten salt in the first salt liquid tank is pumped to the molten salt storage tank by a molten salt return pump, and the rotation speed of the molten salt return pump is controlled so that the molten salt in the first salt liquid tank maintains a certain liquid level height; when the molten salt in the second salt liquid tank reaches a predetermined liquid level height, the opening of the flow control valve is controlled so that the amount of molten salt entering the second salt liquid tank is equal to the amount of molten salt flowing out of the second salt liquid tank through the inlet electrode insulating pipe.

[0017] Through the above-mentioned exemplary embodiments, the advantages of the present invention are: the insulating pipe and the molten salt electrode can be designed according to any power supply voltage and heating power to form a suitable molten salt heating device. The device and method for electrode-type heating of molten salt of the present invention use the molten salt itself as the heating element, without heat conduction loss and the risk of dry burning of the heating wire. The only moving part is the molten salt circulation pump. Once the pump stops running, the heating will also stop. The most important thing is that the present invention successfully solves the technical problem of realizing low current density operation of electrodes in various high conductivity ion conductors at any working voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of an apparatus for heating molten salt according to an exemplary embodiment of the present invention.

[0019] Figure 2 is a schematic diagram of an apparatus for heating molten salt according to another exemplary embodiment of the present invention.

[0020] Figure 3A and Figure 3B It is a cross-sectional schematic diagram of an inlet electrode insulating pipe and / or an outlet electrode insulating pipe in a device for heating molten salt according to the present invention.

[0021] Figure 4A and Figure 4B An example of a molten salt electrode box in an apparatus for heating molten salt according to an exemplary embodiment of the present invention is shown, wherein Figure 4B yes Figure 4A Schematic cross-section of .

[0022] Figure 4C and Figure 4D Another example of a molten salt electrode box in an apparatus for heating molten salt according to an exemplary embodiment of the present invention is shown, wherein Figure 4D yes Figure 4C Side view of.

[0023] Figure 5 is a schematic diagram of an apparatus for heating molten salt according to still another exemplary embodiment of the present invention.

[0024] It should be understood that the drawings are not drawn to scale, but show various features that illustrate the basic principles of the invention in a slightly simplified manner. In the drawings of the present invention, the same reference numerals represent the same or equivalent parts of the present invention. DETAILED DESCRIPTION

[0025] Reference will be made in detail to various embodiments of the present invention, examples of which are shown in the accompanying drawings and are described below. Although the present invention will be described in conjunction with exemplary embodiments of the present invention, it will be understood that this specification is not intended to limit the present invention to those exemplary embodiments. On the contrary, the present invention is intended to cover not only the exemplary embodiments of the present invention, but also various alternatives, modifications, equivalents and other embodiments included within the spirit and scope of the present invention as defined in the appended claims.

[0026] Hereinafter, various exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0027] Figure 1 An apparatus 100 for heating molten salt according to an exemplary embodiment of the present invention is shown, which may include:

[0028] A first salt solution tank 10, which is made of a high temperature resistant and corrosion resistant material and is grounded, and at least one preheater 11 is disposed inside the first salt solution tank 10;

[0029] A second salt solution tank 20, which is made of a high temperature resistant and corrosion resistant material and is grounded, and the second salt solution tank 20 is arranged at a higher position than the first salt solution tank 10;

[0030] At least one group of molten salt electrodes 30, each group of molten salt electrodes 30 includes a plurality of molten salt electrode boxes, and the plurality of molten salt electrode boxes are arranged at a position higher than the first salt solution box 10 and lower than the second salt solution box 20;

[0031] At least one group of electrode inlet insulating pipes 40, the number of pipes in each group of electrode inlet insulating pipes is the same as the number of multiple molten salt electrode boxes in each group of molten salt electrodes, the first end (the upper end) of the electrode inlet insulating pipe 40 is fluidly connected to the second salt solution box 20, and the second end (the lower end) of the electrode inlet insulating pipe 40 is fluidly connected to a corresponding molten salt electrode box in the multiple molten salt electrode boxes, so that the molten salt can flow through the electrode inlet insulating pipe 40;

[0032] At least one group of outlet electrode insulating pipes 50, the number of pipes in each group of outlet electrode insulating pipes is the same as the number of multiple molten salt electrode boxes in each group of molten salt electrodes, the first end (the upper end) of the outlet electrode insulating pipe 50 is fluidically connected to a corresponding molten salt electrode box in the multiple molten salt electrode boxes, and the second end (the lower end) of the outlet electrode insulating pipe 50 is fluidically connected to the first salt liquid box 10, so that the molten salt can flow through the outlet electrode insulating pipe 50;

[0033] A power supply device 60, which includes a multi-phase alternating current, and the number of phases of the multi-phase alternating current is the same as the number of the plurality of molten salt electrode boxes, each phase of the multi-phase alternating current of the power supply device 60 is electrically connected to a corresponding one of the plurality of molten salt electrode boxes;

[0034] A first connecting pipe 12, which connects the first saline tank 10 to the second saline tank 20;

[0035] a molten salt circulation pump 13, which is disposed in the first connecting pipe 12 and is used to pump the molten salt in the first salt liquid tank 10 to the second salt liquid tank 20; and

[0036] The controller 70 is electrically connected to the preheater 11 , the power supply device 60 and the molten salt circulation pump 13 to control the opening or closing of the preheater 11 , the power supply or power off of the power supply device 60 and the rotation speed of the molten salt circulation pump 13 .

[0037] Specifically, in the present exemplary embodiment, the plurality of molten salt electrode boxes of each group of molten salt electrodes 30 is three (in Figure 1 The multiphase AC power is three-phase AC power (represented by L1, L2, L3), and each group of electrode inlet insulating pipes 40 includes three electrode inlet insulating pipes (in Figure 1 41, 42, 43 are used in the figure to represent respectively), each group of electrode insulation pipes 50 includes three electrode insulation pipes (in Figure 1 51, 52, 53 are used in the figure to represent respectively). Specifically, each phase L1, L2, L3 of the three-phase alternating current is electrically connected to three molten salt electrode boxes 31, 32, 33 respectively. It can be understood by those skilled in the art that the three-phase alternating current is only an example, and alternating current with more or fewer phases is also feasible, for example, two-phase alternating current is also feasible.

[0038] exist Figure 1 In the illustrated embodiment, only one group of molten salt electrodes 30 is shown, but those skilled in the art will appreciate that two, three or more groups of molten salt electrodes 30 may be provided, and each group of molten salt electrodes 30 includes a plurality of molten salt electrode boxes (illustrated as each group of molten salt electrodes 30 includes three molten salt electrode boxes 31, 32, 33). Accordingly, taking three-phase alternating current as an example, in the case of three groups of molten salt electrodes 30, the L1 phase of the three-phase alternating current is electrically connected to the first molten salt electrode box 31 of each group of molten salt electrodes 30, the L2 phase of the three-phase alternating current is electrically connected to the second molten salt electrode box 32 of each group of molten salt electrodes 30, and the L3 phase of the three-phase alternating current is electrically connected to the third molten salt electrode box 33 of each group of molten salt electrodes 30. Furthermore, Figure 1Only one group of inlet electrode insulating pipes 40 and one group of outlet electrode insulating pipes 50 are shown, that is, one group of inlet electrode insulating pipes 40 and one group of outlet electrode insulating pipes 50 are provided for one group of molten salt electrodes 30. However, it can be understood by those skilled in the art that, as required, two or more groups of inlet electrode insulating pipes 40 and two or more groups of outlet electrode insulating pipes 50 can be provided for one group of molten salt electrodes 30.

[0039] Specifically, in the present exemplary embodiment, the molten salt flowing in each pipe in each group of inlet electrode insulating pipes 40 generates a first resistance value resistor with the same resistance value, that is, the resistance value generated by the molten salt flowing in each inlet electrode insulating pipe 41, 42, 43 is the same as each other. In addition, the molten salt flowing in each pipe in each group of outlet electrode insulating pipes 50 generates a second resistance value resistor with the same resistance value, that is, the resistance value generated by the molten salt flowing in each outlet electrode insulating pipe 51, 52, 53 is the same as each other.

[0040] In order to make the resistance values ​​generated by the molten salt flowing in each electrode inlet insulating pipe 41, 42, and 43 the same, the electrode inlet insulating pipe can have a cross-section of a circular, elliptical, rectangular, hexagonal or other closed shape, and each insulating pipe is a complete pipe or is composed of multiple short pipes. Each group of electrode inlet insulating pipes has the same flow cross-sectional area and the same length, thereby ensuring that each pipe of each group of electrode inlet insulating pipes has the same resistance value after being filled with molten salt liquid. Furthermore, the electrode inlet insulating pipe is arranged vertically or inclined at a specific angle to the horizontal plane to ensure that the molten salt flowing by gravity has enough flow to carry out all the heat generated. The implementation scheme of the vertical arrangement of the electrode inlet insulating pipe can be as follows: Figure 1 As shown, the embodiment in which the inlet electrode insulating pipe is inclined at a specific angle to the horizontal plane can be as follows Figure 2 As shown. Figure 2 In the embodiment, the angles of each pipe in each group of electrode inlet insulating pipes relative to the horizontal plane are the same, so as to ensure that each group of electrode inlet insulating pipes has the same flow cross-sectional area and the same length, thereby ensuring that each pipe in each group of electrode inlet insulating pipes has the same resistance value after being filled with molten salt liquid.

[0041] Similarly, in order to make the resistance values ​​generated by the molten salt flowing in each of the electrode insulating pipes 51, 52, and 53 the same, the electrode insulating pipes may have a cross-section that is circular, elliptical, rectangular, hexagonal, or other closed shapes. Each insulating pipe is a complete pipe or is composed of multiple short pipes. Each group of electrode insulating pipes has the same flow cross-sectional area and the same length, thereby ensuring that each pipe in each group of electrode insulating pipes has the same resistance value after being filled with molten salt liquid. Furthermore, the electrode insulating pipes are arranged vertically or inclined at a specific angle to the horizontal plane to ensure that the molten salt flowing by gravity has sufficient flow to carry out all the heat generated. The implementation scheme for the vertical arrangement of the electrode insulating pipes may be as follows: Figure 1 As shown, the embodiment in which the outlet electrode insulating pipe is inclined at a specific angle to the horizontal plane can be as follows Figure 2 As shown. Figure 2 In the embodiment, the angles of each pipe in each group of electrode insulating pipes relative to the horizontal plane are the same, so as to ensure that each group of electrode insulating pipes has the same flow cross-sectional area and the same length, thereby ensuring that each pipe in each group of electrode insulating pipes has the same resistance value after being filled with molten salt liquid.

[0042] Preferably, Figure 2 In the illustrated embodiment, the angles of each pipe in each group of inlet electrode insulating pipes relative to the horizontal plane are also the same as the angles of each pipe in each group of outlet electrode insulating pipes relative to the horizontal plane.

[0043] Furthermore, if Figure 3A and Figure 3B As shown, the inlet electrode insulating pipe 40 and / or the outlet electrode insulating pipe 50 may not have a closed cross-section, but may be formed in the form of a "groove", and specifically an insulating pipe groove. The insulating pipe groove has a bottom with a semicircular cross-section or an inverted trapezoidal bottom, or an open cross-section of other shapes. Similarly, each insulating pipe groove is a complete pipe groove or is formed by overlapping multiple short grooves, and each group of inlet electrode insulating pipe grooves has the same flow cross-sectional area and the same length, so that the molten salt in the inlet electrode insulating pipe groove has the same resistance value when flowing, and each group of outlet electrode insulating pipe grooves has the same flow cross-sectional area and the same length, so that the molten salt in the outlet electrode insulating pipe groove has the same resistance value when flowing.

[0044] In a preferred embodiment, the first resistance value and the second resistance value are also the same. That is, the resistance value generated by the molten salt flowing in each inlet electrode insulating pipe 41, 42, 43 and the resistance value generated by the molten salt flowing in each outlet electrode insulating pipe 51, 52, 53 are also the same.

[0045] In an exemplary embodiment of the present invention, the molten salt electrode boxes 31, 32, and 33 are containers made of corrosion-resistant and high-temperature resistant metal materials with a specific inner surface area, and have an inlet electrode insulation pipe connection port and an outlet electrode insulation pipe connection port, the second end of the inlet electrode insulation pipe is fluidly connected to the inlet electrode insulation pipe connection port of the corresponding molten salt electrode box, and the first end of the outlet electrode insulation pipe is fluidly connected to the outlet electrode insulation pipe connection port of the corresponding molten salt electrode box. Further, a partition or a conduit may be provided inside the molten salt electrode box to form a siphon flow channel with the outlet electrode insulation pipe connection port to ensure that a certain liquid level is maintained inside the molten salt electrode box when the molten salt flows, thereby ensuring that the electrode and the molten salt have sufficient contact area, and when the heating is stopped, there is basically no molten salt retention inside the molten salt electrode box or only a small amount of molten salt retention, and further, the outer wall of the molten salt electrode box is connected with a conductive copper bar.

[0046] Specifically, Figure 4A and Figure 4B , which shows an example of a molten salt electrode box in an apparatus for heating molten salt according to an exemplary embodiment of the present invention. Figure 4A and Figure 4B The molten salt electrode box shown has an inlet electrode insulation pipe connection port 34 and an outlet electrode insulation pipe connection port 35. The second end (lower end) of the inlet electrode insulation pipe 40 is fluidically connected to the inlet electrode insulation pipe connection port 34 of the molten salt electrode box, and the first end (upper end) of the outlet electrode insulation pipe 50 is fluidically connected to the outlet electrode insulation pipe connection port 35 of the molten salt electrode box. Figure 4A and Figure 4B In the embodiment shown, a partition 36 is provided inside the molten salt electrode box, which forms a flow channel with the electrode inlet insulation pipe connection port 34 and the electrode outlet insulation pipe connection port 35 to ensure that a certain liquid level is maintained inside the molten salt electrode box when the molten salt flows, thereby ensuring that there is sufficient contact area between the electrode and the molten salt, and when the heating is stopped, there is basically no molten salt retained inside the molten salt electrode box or only a small amount of molten salt is retained. Figure 4A and Figure 4B The conductive copper busbar connected to the outer wall of the molten salt electrode box is not shown in the figure. The conductive copper busbar is a conventional design known to those skilled in the art and is therefore not shown in the figure.

[0047] Furthermore, if Figure 4C and Figure 4D , which shows another example of the molten salt electrode box in the apparatus for heating molten salt according to an exemplary embodiment of the present invention. Figure 4C The molten salt electrode box shown is a container with a specific inner surface area and has an inlet electrode insulation pipe connection port 34 and an outlet electrode insulation pipe connection port 35. Figure 4CIn the embodiment shown, no partition is provided inside the molten salt electrode box. The molten salt electrode box relies on its own volume to ensure that a certain liquid level is maintained inside the molten salt electrode box when the molten salt flows, thereby ensuring that there is sufficient contact area between the electrode and the molten salt, and when heating is stopped, there is basically no molten salt retained inside the molten salt electrode box.

[0048] The method for heating molten salt using the above-mentioned device for heating molten salt is specifically described below, and the method comprises the following steps: using a preheater 11 to heat the salt in the first salt liquid tank 10, and heating the salt to a molten state that can flow; after the salt is in a molten state that can flow, turning off the preheater 11; using a molten salt circulation pump 13 to pump the molten salt in the first salt liquid tank 10 to the second salt liquid tank 20, and controlling the speed of the molten salt circulation pump 13 so that the amount of molten salt entering the second salt liquid tank 20 is more than the amount of molten salt discharged from the second salt liquid tank 20; 0 through the electrode inlet insulating pipe 40; after the molten salt flowing through the electrode inlet insulating pipe 40 enters the molten salt electrode box and correspondingly flows into the first salt solution tank 10 through the electrode outlet insulating pipe 50, the power supply device 60 is turned on to supply power, thereby heating the molten salt; when the molten salt in the second salt solution tank 20 reaches a predetermined liquid level, the speed of the molten salt circulation pump 13 is controlled so that the amount of molten salt entering the second salt solution tank 20 is equal to the amount of molten salt flowing from the second salt solution tank 20 through the electrode inlet insulating pipe 40.

[0049] By the above-mentioned method for heating molten salt, molten salt is pumped from the first salt liquid tank 10 to the second salt liquid tank 20, and then the molten salt in the second salt liquid tank 20 flows into the molten salt electrode tank through the inlet electrode insulating pipe 40 by gravity, and then the molten salt in the molten salt electrode tank flows into the first salt liquid tank 10 through the outlet electrode insulating pipe 50 by gravity, thereby forming a cycle. While the above-mentioned cycle is in progress, the power supply device 60 is turned on to supply power, so that the molten salt is heated.

[0050] The present invention takes three-phase alternating current as an example, and uses electrodes to heat molten salt, which is equivalent to using a star connection of three-phase alternating current. In the star connection, whether the neutral line is connected or not, the current will flow between the phase lines. If the three-phase loads are the same, the vector sum of the three-phase currents is zero, and thus the neutral line current is zero. Therefore, as long as the phase balance between the electrodes is ensured, that is, the molten salt flow rate and flow velocity flowing through the electrodes are the same, and the electrode sizes are the same, the electrodes can heat the molten salt.

[0051] In an exemplary embodiment of the present invention, when heated by the preheater 11, the salt can be heated to 200-275°C to put the salt in a molten state where it can flow, thereby forming the above-mentioned cycle; further, after turning on the power supply device 60, the molten salt can be heated to 300-600°C, or even up to 800°C.

[0052] In a preferred embodiment of the present invention, the molten salt electrode 30 is connected to three-phase alternating current, and the molten salt is heated during the above-mentioned circulation process. The heated high-temperature molten salt flows into the first salt liquid tank, and the molten salt is transported from the first salt liquid tank to a high position by the molten salt circulation pump and flows into the second salt liquid tank for continuous circulation. The molten salt also takes out heat during the circulation process.

[0053] The molten salt heated by the present invention can be used to provide high-temperature steam for industrial use at different temperatures through a heat exchanger, directly provide high-temperature steam to a power plant turbine, and provide steam at different temperatures for brewing, pharmaceuticals, mining, etc. Furthermore, the present invention can utilize the peak-shaving electricity of a power plant to convert electricity into heat for storage or use. The present invention can also directly utilize the electricity generated by waste clean energy to directly convert it into heat for storage or direct use.

[0054] In an exemplary embodiment of the present invention, after the molten salt circulation pump 13 stops, the molten salt in the second salt liquid tank 20, the inlet electrode insulating pipe 40, the molten salt electrode box and the outlet electrode insulating pipe 50 all or substantially all fall back into the first salt liquid tank 10 under the action of gravity, and the heating is also stopped. Specifically, the molten salt electrode box of the present invention has a container shape, and a partition or a conduit is provided inside the molten salt electrode box to form a siphon flow channel with the outlet electrode insulating pipe connection port 35, so that when heating, it is ensured that there is enough liquid level height inside the electrode to ensure that the electrode and the molten salt have enough contact area, and when the heating is stopped, the molten salt can be made to flow out of the electrode all or substantially all under the action of siphon to prevent freezing. In certain embodiments, there may be a small amount of molten salt retained inside the molten salt electrode box, but as long as it does not affect the flow of the molten salt when it is used again, there will be no adverse effect. When used again, the hot molten salt will melt the frozen molten salt, so that it keeps flowing.

[0055] In an exemplary embodiment of the present invention, according to the above-mentioned method for heating molten salt, when the heating is about to be terminated, the rotation speed of the molten salt circulation pump 13 can be controlled so that the amount of molten salt entering the second salt liquid tank 20 is less than the amount of molten salt flowing away from the second salt liquid tank 20 through the inlet electrode insulating pipe 40. In this way, the liquid level in the second salt liquid tank 20 can be gradually reduced, and the heating is terminated when it is reduced to a certain height, thereby further improving the effect and making it easier to prevent the molten salt from freezing.

[0056] Furthermore, if Figure 5 , which shows a schematic diagram of an apparatus for heating molten salt according to yet another exemplary embodiment of the present invention.

[0057] In a device for heating molten salt according to another exemplary embodiment of the present invention, it is further provided with:

[0058] A molten salt storage tank 80 having a volume greater than that of the first salt solution tank 10, wherein a plurality of preheaters (not shown) are disposed inside the molten salt storage tank 80;

[0059] A second connecting pipe 81, which connects the first salt liquid tank 10 to the molten salt storage tank 80;

[0060] A molten salt return pump 82 is disposed in the second connecting pipe 81 and is used to pump the molten salt in the first salt liquid tank 10 to the molten salt storage tank 80;

[0061] A third connecting pipe 83, which connects the molten salt storage tank 80 to the second salt liquid tank 20; and

[0062] a flow control valve 84, which is disposed in the third connecting pipeline 83;

[0063] Among them, the controller 70 is further electrically connected to multiple pre-heaters in the molten salt storage tank 80, a molten salt return pump 82 and a flow control valve 84 to control the opening or closing of the multiple pre-heaters in the molten salt storage tank, the rotation speed of the molten salt return pump 82 and the opening degree of the flow control valve 84.

[0064] Specifically, in Figure 5 In the embodiment shown, the connection between the controller 70 and the multiple preheaters in the molten salt storage tank 80, the molten salt return pump 82 and the flow control valve 84 is not specifically shown, but reference Figure 1 In the embodiment shown in the figure, those skilled in the art can clearly know the connection mode between the controller 70 and the multiple preheaters in the molten salt storage tank 80, the molten salt return pump 82 and the flow control valve 84, so there is no need to explain it in detail. Figure 5 Shown in the middle.

[0065] Further, in Figure 5 In the embodiment shown, no Figure 1 The first connecting pipe 12 and the molten salt circulation pump 13 are shown in FIG. 1 , but those skilled in the art will appreciate that Figure 5 The embodiment shown may have a first connecting pipe 12 and a molten salt circulation pump 13 .

[0066] The following describes the use of Figure 5The method for heating molten salt by using the device for heating molten salt shown in the figure comprises the following steps: using a preheater to heat the salt in the first salt liquid tank 10 and / or the molten salt storage tank 80, and heating the salt to a molten state capable of flowing; after the salt is in a molten state capable of flowing, closing the preheater; adjusting the flow control valve 84 so that the molten salt in the molten salt storage tank 80 flows into the second salt liquid tank 20, and controlling the opening of the flow control valve 84 so that the amount of molten salt entering the second salt liquid tank 20 is greater than the amount of molten salt flowing out of the second salt liquid tank 20 through the electrode inlet insulating pipe 40; and the amount of molten salt flowing through the electrode inlet insulating pipe 40 is controlled. After the molten salt enters the molten salt electrode box and flows into the first salt liquid tank 10 through the electrode outlet insulating pipe 50 accordingly, the power supply device 60 is turned on to supply power, thereby heating the molten salt; the molten salt in the first salt liquid tank 10 is pumped to the molten salt storage tank 80 by the molten salt return pump 82, and the rotation speed of the molten salt return pump 82 is controlled so that the molten salt in the first salt liquid tank 10 maintains a certain liquid level height; when the molten salt in the second salt liquid tank 20 reaches a predetermined liquid level height, the opening of the flow control valve 84 is controlled so that the amount of molten salt entering the second salt liquid tank 20 is equal to the amount of molten salt flowing out of the second salt liquid tank 20 through the electrode inlet insulating pipe 40.

[0067] Through the various exemplary embodiments described above, the advantages of the present invention are: the insulating pipe and the molten salt electrode can be designed according to any power supply voltage and heating power to form a suitable molten salt heating device. The device and method for electrode-type heating of molten salt of the present invention use the molten salt itself as a heating element, without heat conduction loss, and without the risk of dry burning of the heating wire. The only moving part is the molten salt pump (including the molten salt circulation pump and / or the molten salt return pump). Once the pump stops running, the heating will also stop. The most important thing is that the present invention successfully solves the technical problem of realizing low current density operation of electrodes in various high conductivity ion conductors at any working voltage.

[0068] Finally, in order to more clearly illustrate the present invention, the applicant provides the following examples. The size design of the insulating tube of the present invention regards the molten salt flowing through the insulating tube as a cylindrical resistor, whose resistance is R = ρ*L / S, where R is the resistance of the cylindrical resistor, ρ is the conductivity of the molten salt, L is the length of the insulating tube, and S is the inner diameter area of ​​the cross section of the insulating tube. When L / s reaches a certain value, the resistance of the molten salt flowing through the insulating tube can be very large, so after passing through the insulating tube, the molten salt current is very small.

[0069] The above descriptions of the specific exemplary embodiments of the present invention are presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise form disclosed, and it is obvious that many modifications and changes can be made according to the above teachings. The selection and description of the exemplary embodiments are to explain certain principles of the present invention and their practical applications, so that those skilled in the art can make and use various exemplary embodiments of the present invention and their different alternative forms and modified forms. The scope of the present invention is intended to be limited by the appended claims and their equivalents.

Claims

1. A device for heating molten salt, characterized in that: include: A first salt solution tank, wherein at least one preheater is disposed inside the first salt solution tank; a second saline tank, which is arranged at a higher position than the first saline tank; At least one group of molten salt electrodes, each group of molten salt electrodes comprising a plurality of molten salt electrode boxes, wherein the plurality of molten salt electrode boxes are arranged at a position higher than the first salt solution box and lower than the second salt solution box; at least one group of inlet electrode insulation pipes, the number of pipes in each group of inlet electrode insulation pipes is the same as the number of multiple molten salt electrode boxes in each group of molten salt electrodes, the first end of the inlet electrode insulation pipe is fluidically connected to the second salt solution box, and the second end of the inlet electrode insulation pipe is fluidically connected to a corresponding one of the multiple molten salt electrode boxes, so that molten salt can flow through the inlet electrode insulation pipe; At least one group of outlet electrode insulation pipes, the number of pipes in each group of outlet electrode insulation pipes is the same as the number of multiple molten salt electrode boxes in each group of molten salt electrodes, the first end of the outlet electrode insulation pipe is fluidically connected to a corresponding one of the multiple molten salt electrode boxes, and the second end of the outlet electrode insulation pipe is fluidically connected to the first salt liquid box, so that molten salt can flow through the outlet electrode insulation pipe; A power supply device, comprising a multi-phase alternating current, wherein the number of phases of the multi-phase alternating current is the same as the number of the plurality of molten salt electrode boxes, each phase of the multi-phase alternating current of the power supply device being electrically connected to a corresponding one of the plurality of molten salt electrode boxes; a first connecting pipe connecting the first saline tank fluid to the second saline tank; a molten salt circulation pump, which is arranged in the first connecting pipeline and is used to pump the molten salt in the first salt liquid tank to the second salt liquid tank; and a controller electrically connected to the preheater, the power supply device and the molten salt circulation pump to control the opening or closing of the preheater, the power supply or power off of the power supply device and the rotation speed of the molten salt circulation pump; Wherein, each group of molten salt electrodes has three molten salt electrode boxes, the multiphase alternating current is three-phase alternating current, each group of inlet electrode insulating pipes includes three inlet electrode insulating pipes, and each group of outlet electrode insulating pipes includes three outlet electrode insulating pipes; The molten salt flowing in each pipe in each group of inlet electrode insulation pipes generates resistors with the same first resistance value, and the molten salt flowing in each pipe in each group of outlet electrode insulation pipes generates resistors with the same second resistance value.

2. The device for heating molten salt according to claim 1, wherein: The first resistance value and the second resistance value are also the same.

3. The device for heating molten salt according to claim 1, wherein: The molten salt electrode box is made of corrosion-resistant and high-temperature resistant metal material to form a container with an inner surface area, and has an electrode inlet insulation pipe connection port and an electrode outlet insulation pipe connection port. The second end of the electrode inlet insulation pipe is fluidically connected to the electrode inlet insulation pipe connection port of the corresponding molten salt electrode box, and the first end of the electrode outlet insulation pipe is fluidically connected to the electrode outlet insulation pipe connection port of the corresponding molten salt electrode box; and a conductive copper bus is connected to the outer wall of the molten salt electrode box.

4. The device for heating molten salt according to claim 1, wherein: The inlet electrode insulating pipe and the outlet electrode insulating pipe are formed in the form of a "pipe" or a "trough"; The electrode inlet insulation pipeline is inclined at an angle to the horizontal plane, the angles of the pipelines in each group of electrode inlet insulation pipelines relative to the horizontal plane are the same, the lengths of the pipelines in each group of electrode inlet insulation pipelines are the same, and the flow cross-sectional areas of the pipelines in each group of electrode inlet insulation pipelines are the same, so as to ensure that the flow rates of the pipelines in each group of electrode inlet insulation pipelines are the same; The electrode insulation pipes are inclined at an angle to the horizontal plane, the angles of the pipes in each group of electrode insulation pipes relative to the horizontal plane are the same, the lengths of the pipes in each group of electrode insulation pipes are the same, and the flow cross-sectional areas of the pipes in each group of electrode insulation pipes are the same, so as to ensure that the flow rates of the pipes in each group of electrode insulation pipes are the same.

5. The device for heating molten salt according to any one of claims 1 to 4, further comprising: A molten salt storage tank having a volume greater than that of the first salt solution tank, wherein a plurality of preheaters are arranged inside the molten salt storage tank; a second connecting pipe, which connects the first salt liquid tank fluid to the molten salt storage tank; a molten salt return pump, which is arranged in the second connecting pipe and is used to pump the molten salt in the first salt liquid tank to the molten salt storage tank; a third connecting pipe, which connects the molten salt storage tank fluid to the second salt liquid tank; as well as a flow control valve, which is arranged in the third connecting pipeline; Wherein, the controller is further electrically connected to multiple pre-heaters in the molten salt storage tank, the molten salt return pump and the flow control valve to control the opening or closing of multiple pre-heaters in the molten salt storage tank, the rotation speed of the molten salt return pump and the opening of the flow control valve.

6. A method for heating molten salt, using the device for heating molten salt according to any one of claims 1 to 4, the method comprising the following steps: Using a preheater to heat the salt in the first salt liquid tank, and heating the salt to a molten state capable of flowing; After the salt is in a molten state capable of flowing, the preheater is turned off; Using a molten salt circulation pump to pump the molten salt in the first salt liquid tank to the second salt liquid tank, and controlling the rotation speed of the molten salt circulation pump so that the amount of molten salt entering the second salt liquid tank is greater than the amount of molten salt flowing out of the second salt liquid tank through the electrode inlet insulation pipe; After the molten salt flowing through the inlet electrode insulating pipe enters the molten salt electrode box and correspondingly flows through the outlet electrode insulating pipe into the first salt solution box, the power supply device is turned on to supply power, thereby heating the molten salt; When the molten salt in the second salt liquid tank reaches a predetermined liquid level, the rotation speed of the molten salt circulation pump is controlled so that the amount of molten salt entering the second salt liquid tank is equal to the amount of molten salt flowing out of the second salt liquid tank through the electrode inlet insulation pipe.

7. The method for heating molten salt according to claim 6, when preparing to end heating, controlling the rotating speed of the molten salt circulation pump so that the amount of molten salt entering the second salt solution tank is less than the amount of molten salt flowing away from the second salt solution tank through the electrode inlet insulation pipeline.

8. A method for heating molten salt, using the device for heating molten salt according to claim 5, the method comprising the following steps: Using a preheater to heat the salt in the first salt liquid tank and / or the molten salt storage tank, and heating the salt to a molten state capable of flowing; After the salt is in a molten state capable of flowing, the preheater is turned off; Adjust the flow control valve so that the molten salt in the molten salt storage tank flows into the second salt liquid tank, and control the opening of the flow control valve so that the amount of molten salt entering the second salt liquid tank is greater than the amount of molten salt flowing out of the second salt liquid tank through the electrode inlet insulating pipe; After the molten salt flowing through the inlet electrode insulating pipe enters the molten salt electrode box and correspondingly flows through the outlet electrode insulating pipe into the first salt solution box, the power supply device is turned on to supply power, thereby heating the molten salt; The molten salt in the first salt liquid tank is pumped to the molten salt storage tank by using a molten salt return pump, and the rotation speed of the molten salt return pump is controlled so that the molten salt in the first salt liquid tank maintains a certain liquid level height; When the molten salt in the second salt liquid tank reaches a predetermined liquid level, the opening of the flow control valve is controlled so that the amount of molten salt entering the second salt liquid tank is equal to the amount of molten salt flowing out of the second salt liquid tank through the electrode inlet insulation pipe.

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