Distributed molten salt thermal storage system

Abstract

The distributed molten salt heat storage system aims to provide a molten salt heating by using solar energy and wind energy and low valley electricity, store and convert the heat energy generated by clean energy through the molten salt heat storage unit, supply the heat energy to residents, and comprehensively arrange the electric energy input and heat energy output of each molten salt heat storage system by using the heat storage intelligent control unit, solve the comprehensive utilization of the molten salt heat storage systems distributed in multiple places, realize the distributed heat storage of "storing heat for the people", and provide protection for the clean heating of the residents in the rural concentrated residential areas and the heat energy demand of agricultural planting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat storage, in particular to a distributed molten salt heat storage system. BACKGROUND

[0002] With a large number of rural construction concentrated residential areas emerging rapidly in many towns, in order to improve the living standards of rural residents, centralized heating has become an important supporting measure for the construction of concentrated residential areas. At present, the construction of wind power and solar power generation is popular around the concentrated residential areas in rural construction, and wind power generation and solar power generation as a new type of renewable resource and clean energy can reduce the pollution of the living environment of people and promote the development of economy. However, due to the insufficient peak shaving capacity of existing wind power generation and solar power generation, the difficulty of new energy grid connection and consumption, and other reasons, the problems of "abandoning wind and light" have occurred. Therefore, by using the heat storage of wind energy and solar energy, and through heat storage and conversion, the heat energy generated by clean energy can be supplied to residents for use, realizing the distributed heat storage of "storing heat for the people", and providing protection for the heat supply of rural concentrated residential areas. Molten salt heat storage mainly uses wind power generation, solar power generation and low valley electricity to heat the molten salt heat storage device, stores heat in the molten salt heat storage tank, and uses high-temperature molten salt to heat water when heating. The low-temperature molten salt after heat exchange is heated again, forming a complete cycle of molten salt heating-temperature rising-heat exchange-temperature falling, realizing clean heating for concentrated residential areas, or supplying heat source for agricultural greenhouse.

[0003] The invention patent with application number CN202310296579.X proposes a rural household heating system, control method, medium, device and terminal, and the related equipment cost, high-temperature safety and solar power generation use efficiency in the disclosed content are doubtful, and the land use of the equipment is not friendly to the intensive use of rural land. The invention patent with application number CN202311297946.4 proposes a molten salt single-tank heat storage device capable of natural convection circulation, which divides the containing cavity into a heat release circulation cavity and a heat absorption circulation cavity by setting a partition component, and realizes the convection circulation of molten salt. The device structure of the disclosed content is relatively complex. SUMMARY

[0004] The purpose of the present application is to provide a distributed molten salt heat storage system, and to provide a molten salt heating device that uses wind power generation, solar power generation and low valley electricity, stores and converts heat energy through a molten salt heat storage unit, supplies heat energy generated by clean energy to residents for use, and uses a heat storage intelligent control unit to arrange the power input and heat energy output of the molten salt heat storage system, and realizes the comprehensive utilization of the molten salt heat storage system distributed in multiple places.

[0005] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0006] The distributed molten salt heat storage system comprises a molten salt heat storage unit and a heat storage intelligent control unit.

[0007] The molten salt heat storage unit comprises a heat storage tank, an electric heater, molten salt, heat conducting oil, a heat conducting sleeve, a heat pipe, a heat exchanger and a lifting mechanism.

[0008] The heat storage intelligent control unit comprises a controller, an electric heater controller, an over-temperature protector, an over-pressure alarm and a flow controller.

[0009] The heat storage tank of the molten salt heat storage unit can adopt a single-tank structure.

[0010] The heat storage tank is made of S31603 stainless steel, the heat insulation layer of the tank wall and the tank top is made of aluminum silicate fiber felt, and the tank bottom is made of S31603 stainless steel, aluminum silicate fiber felt, an aluminum layer, heat-insulating refractory bricks and foamed glass in sequence.

[0011] The electric heater of the molten salt heat storage unit is arranged at the middle position of the bottom of the heat storage tank, receives input from wind power generation, solar power generation and off-peak electricity, and realizes heating of the molten salt.

[0012] The molten salt of the molten salt heat storage unit is one of binary salt and ternary salt.

[0013] Preferably, the binary salt is composed of 60% of sodium nitrate (NaNO3) and 40% of potassium nitrate (KNO3) by mass ratio.

[0014] Preferably, the ternary salt is composed of 53% of potassium nitrate (KNO3) + 40% of sodium nitrite (NaNO2) + 7% of sodium nitrate (NaNO3) by mass ratio.

[0015] The heat conducting oil of the molten salt heat storage unit is one of alkyl biphenyl ether type heat conducting oil and mineral type heat conducting oil.

[0016] The heat conducting sleeve of the molten salt heat storage unit has an inner cavity structure, the heat conducting oil is stored in the inner cavity of the heat conducting sleeve, and the lower part of the heat conducting sleeve in contact with the molten salt is in a concave structure.

[0017] Preferably, the material of the heat conducting sleeve is one of S31603 stainless steel and J347H stainless steel.

[0018] Preferably, the concave structure of the lower part of the heat conducting sleeve is one of a polyline and a curve.

[0019] The heat pipe of the molten salt heat storage unit is composed of a pipe shell, a wick and an end cover, and the evaporation end is immersed in the heat conducting oil in the heat conducting sleeve.

[0020] Preferably, the material of the pipe shell of the heat pipe is one of carbon steel, stainless steel and copper alloy.

[0021] Preferably, the wick material of the heat pipe is one of metal braid, carbon fiber;

[0022] Preferably, the working medium of the heat pipe is one of liquid sodium, water;

[0023] Preferably, the number of heat pipes is related to the size of the heat flow density to be transmitted, and is at least 2.

[0024] The heat exchanger of the molten salt heat storage unit is a heat exchange container in which the cooling water is heated to become hot water or steam which is delivered to the outside for heating.

[0025] The lifting mechanism of the molten salt heat storage unit is a spiral device, which adjusts the heat exchange area between the evaporation end of the heat pipe and the thermal oil through the lifting mechanism to control the heat flow density.

[0026] In the molten salt heat storage unit, the electric heater at the center of the tank bottom heats the molten salt, which flows upward under the action of buoyancy. The heat of the molten salt is transferred to the thermal oil through the heat conduction sleeve. The working medium in the heat pipe under negative pressure rapidly vaporizes after the evaporation end of the heat pipe immersed in the thermal oil absorbs heat. The working medium vapor flows to the condensation end under the power of the wick heat diffusion. The condensation end of the heat pipe in the heat exchanger exchanges heat with the cooling water.

[0027] Further, during the heating process of the molten salt by the electric heater, the heated molten salt flows upward under the action of buoyancy to the lower part of the heat conduction sleeve. Due to the extremely high heat transfer efficiency of the heat pipe, the molten salt in the lower part of the heat conduction sleeve cools rapidly and becomes denser. Under the constraint of the concave fold or curve structure in the lower part of the heat conduction sleeve, the rising hot molten salt with smaller density pushes the cooled molten salt along the surface of the lower part of the heat conduction sleeve to flow downward to the wall surface of the heat storage tank. In this way, the heated molten salt flows upward in the center of the heat storage tank, and the cooled molten salt flows downward along the wall surface of the heat storage tank, forming a flow circulation of the molten salt in the heat storage tank.

[0028] The heat storage intelligent control unit provides heating, heat transfer, temperature control, pressure control, flow control, and multi-system intelligent coordination control for the heat storage system through the controller.

[0029] Further, the controller of the heat storage intelligent control unit can be one of a single-chip microcomputer, STM32, and PLC.

[0030] Further, the controller of the heat storage intelligent control unit can select the input of wind energy, solar energy, and off-peak electricity according to the current energy situation and the state of the heat storage system.

[0031] Further, the heat storage intelligent regulation unit controller can control the lifting mechanism according to the temperature, pressure and flow parameters of the heat storage system, adjust the contact area of the evaporation end of the heat pipe and the heat conducting oil, control the heat flux density of the heat transfer process, and thus control the temperature and flow of the output hot water or steam.

[0032] Further, the heat storage intelligent regulation unit controller can adjust the input mode of the energy required for the normal operation of the heat storage system according to the weather forecast for several days in the future, due to the size of the wind, rainy or cloudy conditions.

[0033] Preferably, if the wind energy and solar energy are weak in the next 1-2 days, the valley electricity input in part of the period is increased to balance the heat energy storage of the heat storage tank.

[0034] Preferably, if the wind energy and solar energy are weak in the next 3-5 days, the valley electricity input in all periods is increased to balance the heat energy storage of the heat storage tank.

[0035] Preferably, if the wind energy and solar energy are weak for more than 5 days in the future, according to the heat energy storage of the heat storage tank, the valley electricity input in all periods is increased, and the peak electricity input in part or all periods is increased to ensure the normal operation of the heat storage system.

[0036] According to the distribution of wind energy and solar energy, a plurality of different capacity molten salt heat storage systems matched with the centralized residential area are arranged, and the heat storage intelligent regulation unit controller can comprehensively arrange the electricity input and heat output of each molten salt heat storage system.

[0037] Preferably, the centralized residential area is provided with two molten salt heat storage systems, and at least one molten salt heat storage system is arranged according to the weather forecast, and the energy input is performed according to the priority order of wind energy, solar energy, valley electricity and peak electricity. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The figure is a structure diagram of the molten salt heat storage unit of the distributed molten salt heat storage system of the embodiment of the application. In the figure, 1 is a heat storage tank, 2 is an electric heater, 3 is molten salt, 4 is heat conducting oil, 5 is a heat conducting sleeve, 6 is a heat pipe, 7 is a heat exchanger, and 8 is a lifting mechanism.

[0039] Figure 2 The figure is a control system diagram of the heat storage intelligent regulation unit of the distributed molten salt heat storage system of the embodiment of the application.

[0040] Figure 3 The figure is a schematic diagram of the heat conducting sleeve with a polyline structure of the embodiment of the application.

[0041] Figure 4 The figure is a schematic diagram of the heat conducting sleeve with a curve structure of the embodiment of the application. DETAILED DESCRIPTION

[0042] The application is described below Figure 1 , Figure 2 , Figure 3 , Figure 4 A preferred embodiment of the distributed molten salt heat storage system of the application is given to illustrate the structural features, technical performance and functional characteristics of the application, but not to limit the scope of the application.

[0043] Figure 1 The molten salt heat storage unit of the distributed molten salt heat storage system comprises a heat storage tank 1, an electric heater 2, molten salt 3, heat conducting oil 4, a heat conducting sleeve 5, a heat pipe 6, a heat exchanger 7, and a lifting mechanism 8.

[0044] Figure 2 The control system diagram of the heat storage intelligent control unit of the distributed molten salt heat storage system of the application;

[0045] Figure 3 The heat conducting sleeve with a polyline structure in the molten salt heat storage unit of the distributed molten salt heat storage system;

[0046] Figure 4 The heat conducting sleeve with a curve structure in the molten salt heat storage unit of the distributed molten salt heat storage system.

[0047] The distributed molten salt heat storage system comprises a molten salt heat storage unit and a heat storage intelligent control unit.

[0048] The molten salt heat storage unit comprises a heat storage tank 1, an electric heater 2, molten salt 3, heat conducting oil 4, a heat conducting sleeve 5, a heat pipe 6, a heat exchanger 7, and a lifting mechanism 8.

[0049] The heat storage intelligent control unit comprises a controller, an electric heater controller, an over-temperature protector, an over-pressure alarm, a flow controller, and a heat exchanger controller.

[0050] The heat storage tank 1 of the molten salt heat storage unit adopts a single tank structure.

[0051] Preferably, the material of the heat storage tank 1 is S31603 stainless steel, the material of the heat insulation layer of the tank wall and the tank top is aluminum silicate fiber felt, and the materials of the tank bottom are S31603 stainless steel, aluminum silicate fiber felt, an aluminum layer, heat-insulating refractory bricks, and foam glass in sequence.

[0052] The electric heater 2 of the molten salt heat storage unit is arranged at the middle position of the bottom of the heat storage tank 1, receives input from wind power generation, solar power generation, and off-peak electricity, and realizes heating of the molten salt 3.

[0053] The molten salt 3 of the molten salt heat storage unit is a binary salt or a ternary salt.

[0054] Preferably, the binary salt consists of sodium nitrate (NaNO3) and potassium nitrate (KNO3) in a mass ratio of 60% and 40%, respectively.

[0055] Preferably, the ternary salt consists of potassium nitrate (KNO3), sodium nitrite (NaNO2) and sodium nitrate (NaNO3) in a mass ratio of 53%, 40% and 7%, respectively.

[0056] The heat conducting oil 4 of the molten salt heat storage unit is one of alkyl biphenyl ether type heat conducting oil and mineral type heat conducting oil.

[0057] The heat conducting sleeve 5 of the molten salt heat storage unit has an inner cavity structure, and the heat conducting oil 4 is stored in the inner cavity of the heat conducting sleeve 5. The lower part of the heat conducting sleeve 5 in contact with the molten salt 3 is concave.

[0058] Preferably, the material of the heat conducting sleeve 5 is one of S31603 stainless steel and J347H stainless steel.

[0059] Preferably, the concave structure of the lower part of the heat conducting sleeve 5 is one of polyline and curve.

[0060] The heat pipe 6 of the molten salt heat storage unit consists of a pipe shell, a wick and an end cover. The evaporation end is immersed in the heat conducting oil 4 in the heat conducting sleeve 5.

[0061] Preferably, the material of the pipe shell of the heat pipe 6 is one of carbon steel, stainless steel and copper alloy.

[0062] Preferably, the material of the wick of the heat pipe 6 is one of metal braid and carbon fiber.

[0063] Preferably, the working medium of the heat pipe 6 is one of liquid sodium and water.

[0064] Preferably, the number of the heat pipe 6 is related to the size of the heat flux to be transmitted, and is at least 2.

[0065] The heat exchanger 7 of the molten salt heat storage unit is a heat exchanger for the condensation end of the heat pipe 6 and cooling water. The cooling water is heated in the heat exchanger 7 to become hot water or steam which is delivered to the outside for heating.

[0066] The lifting mechanism 8 of the molten salt heat storage unit is a spiral device. The heat energy exchange area between the evaporation end of the heat pipe 6 and the heat conducting oil 4 is adjusted by the lifting mechanism 8 to achieve the purpose of controlling the heat flux.

[0067] The molten salt heat storage unit, in the heat storage tank 1, the electric heater 2 at the center position of the tank bottom heats the molten salt 3, the heated molten salt 3 flows upward under the action of buoyancy, the heat of the molten salt 3 is transferred to the heat conducting oil 4 through the heat conducting sleeve 5, the working medium in the heat pipe 6 rapidly vaporizes under the negative pressure state after the evaporation end of the heat pipe 6 absorbs heat immersed in the heat conducting oil 4, the working medium vapor flows to the condensing end under the power action of the wick heat diffusion, the condensing end of the heat pipe 6 in the heat exchanger 7 exchanges heat with the cooling water to become hot water or steam which is transmitted to the outside for heating.

[0068] Further, in the heating process of the electric heater 2, the heated molten salt 3 flows upward under the action of buoyancy to the lower part of the heat conducting sleeve 5, due to the extremely high heat transfer efficiency of the heat pipe 6, the molten salt 3 in the lower part of the heat conducting sleeve 5 rapidly cools down and becomes denser, under the constraint of the concave line type or curve type structure in the lower part of the heat conducting sleeve 5, the hot molten salt 3 with smaller density continuously pushes the cooled molten salt 3 to flow downward along the surface of the concave lower part of the heat conducting sleeve 5 to the direction of the wall surface of the heat storage tank 1, in this way, the heated molten salt 3 flows upward in the central part of the heat storage tank 1, and the cooled molten salt 3 flows downward along the wall surface of the heat storage tank 1, forming the flow circulation of the molten salt 3 in the heat storage tank 1.

[0069] The heat storage intelligent control unit provides heating, heat transfer, temperature control, pressure, flow control and multi-system intelligent coordination control for the heat storage system through the controller.

[0070] Further, the heat storage intelligent control unit controller can be one of a single-chip microcomputer, STM32 and PLC;

[0071] Further, the heat storage intelligent control unit controller can select the input of wind energy, solar energy and off-peak electricity according to the current energy situation and the state of the heat storage system;

[0072] Further, the heat storage intelligent control unit controller can control the output of hot water or steam by adjusting the contact area of the evaporation end of the heat pipe 6 with the heat conducting oil 4 and controlling the heat flux density in the heat transfer process according to the temperature, pressure and flow parameters of the heat storage system through the lifting mechanism 8;

[0073] Further, the heat storage intelligent control unit controller can adjust the energy input mode required for the normal operation of the heat storage system affected by the wind size, rainy or cloudy conditions according to the weather forecast for several days in the future;

[0074] Preferably, if the wind energy and solar energy are weak in the next 1-2 days, the off-peak electricity input in part of the period is increased to balance the heat energy storage of the heat storage tank;

[0075] Preferably, if the wind energy and solar energy are weak in the next 3-5 days, the low-valley electricity input in all time periods is increased to balance the heat energy storage of the heat storage tank.

[0076] Preferably, if the wind energy and solar energy are weak in more than 5 days, according to the heat energy storage of the heat storage tank, the low-valley electricity input in all time periods and the peak electricity input in part or all time periods are increased to ensure the normal operation of the heat storage system.

[0077] According to the distribution of wind energy and solar energy, a plurality of molten salt heat storage systems with different capacities are arranged in the centralized residential area, and the heat storage intelligent control unit controller can comprehensively arrange the electricity input and heat output of the molten salt heat storage systems.

[0078] Preferably, the centralized residential area is provided with two or more molten salt heat storage systems, and at least one molten salt heat storage system is arranged according to the priority order of wind energy, solar energy, low-valley electricity and peak electricity.

[0079] The beneficial effects of the present application are as follows:

[0080] A distributed molten salt heat storage system is provided, the molten salt heat storage unit uses wind energy, solar energy and low-valley electricity to heat the molten salt in the heat storage tank to realize heat energy storage and conversion, and the heat energy generated by clean energy is supplied to residents for use, the heat storage intelligent control unit comprehensively arranges the electricity input and heat output of the plurality of molten salt heat storage systems, solves the comprehensive utilization of the molten salt heat storage systems distributed in multiple places, realizes the distributed heat storage of "storing heat for the people", and provides guarantee for the clean heating of the residents in the centralized residential area and the heat energy demand of agricultural planting.

[0081] In summary, the embodiments of the present application are described above, and obviously the embodiments of the present application are not limited to this. The description of the specific embodiments is only to help understanding the present application, and is not used to limit the present application. Any person skilled in the art can make some modifications and changes to the present application by using the idea of the present application, as long as the technical means does not deviate from the idea and key points of the present application, and still falls within the protection scope of the present application.

Claims

1. A distributed molten salt thermal storage system, characterized by, The application relates to a molten salt heat storage unit and a heat storage intelligent control unit. The molten salt heat storage unit comprises a heat storage tank (1), an electric heater (2), molten salt (3), heat conducting oil (4), a heat conducting sleeve (5), a heat pipe (6), a heat exchanger (7) and a lifting mechanism (8). The heat storage intelligent control unit comprises a controller, an electric heater controller, an over-temperature protector, an over-pressure alarm, a flow controller and a heat exchanger controller. The heat conducting sleeve (5) of the molten salt heat storage unit has an inner cavity structure, the heat conducting oil (4) is stored in the inner cavity of the heat conducting sleeve, and the lower part of the heat conducting sleeve (5) in contact with the molten salt (3) is concave. The inner concave structure of the lower part of the heat conducting sleeve (5) is a broken line type or a curve type. The lifting mechanism (8) of the molten salt heat storage unit is a spiral mechanism, the heat exchange area between the evaporation end of the heat pipe (6) and the heat conducting oil (4) is adjusted through the lifting mechanism (8), so that the heat flow density is controlled. During the heating process of the molten salt (3) in the heat storage tank (1) of the molten salt heat storage unit by the electric heater (2), the heated molten salt (3) flows upwards to the lower part of the heat conducting sleeve (5) under the action of the buoyancy force, the molten salt (3) in the lower part of the heat conducting sleeve (5) is rapidly cooled and has a larger density due to the high heat transfer efficiency of the heat pipe (6), the hot molten salt (3) with a smaller density continuously rises and pushes the cooled molten salt (3) to flow downwards along the inner concave surface of the lower part of the heat conducting sleeve (5) to the wall surface of the heat storage tank (1), so that the heated molten salt (3) flows upwards in the central part of the heat storage tank (1), and the cooled molten salt (3) flows downwards along the wall surface of the heat storage tank (1), thereby forming a flow circulation of the molten salt (3) in the heat storage tank (1). The controller of the heat storage intelligent control unit provides heating, heat transfer, temperature control, pressure, flow control and multi-system intelligent coordination control for the heat storage system. The controller of the heat storage intelligent control unit can select wind energy, solar energy and off-peak electricity according to the current energy situation and the state of the heat storage system. The controller of the heat storage intelligent control unit can adjust the contact area between the evaporation end of the heat pipe (6) and the heat conducting oil (4) by operating the lifting mechanism according to the temperature, pressure and flow parameters of the heat storage system, so as to control the heat flow density of the heat transfer process and control the output of hot water or steam. The controller of the heat storage intelligent control unit can adjust the energy input mode required for the normal operation of the heat storage system due to the influence of the wind size, rainy day or cloudy day according to the weather forecast of the next several days. 2.The heat storage intelligent regulation unit according to claim 1, characterized in that: If the wind energy and solar energy are weak in the next 1-2 days, the off-peak electricity input of part of the period is increased to balance the heat energy storage of the heat storage tank. If the wind energy and solar energy are weak in the next 3-5 days, the off-peak electricity input of all periods is increased to balance the heat energy storage of the heat storage tank. If the wind energy and solar energy are weak for more than 5 days in the future, the off-peak electricity input of all periods is increased according to the heat energy storage of the heat storage tank, and the peak electricity input of part or all periods is increased to ensure the normal operation of the heat storage system. ​ 3.The heat storage intelligent regulation unit according to claim 2, characterized in that: According to the distribution of wind energy and solar energy, a plurality of different capacity molten salt heat storage systems matched with the centralized residential area are arranged, and the heat storage intelligent control unit controller can comprehensively arrange the electric energy input and heat energy output of the molten salt heat storage systems by using the molten salt heat storage systems distributed everywhere. The centralized residential area is provided with two or more molten salt heat storage systems, and at least one molten salt heat storage system is arranged to input energy according to the priority of wind energy, solar energy, low valley electricity and peak electricity according to the weather forecast.

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