CN110726319A - Solid-liquid phase change energy storage device for dispersed filling of molten salt - Google Patents

Abstract

The invention belongs to the field of energy storage, and particularly relates to a solid-liquid phase change energy storage device for dispersed filling of molten salt. It includes thermal insulation shell, the energy storage body, heat accumulation return circuit, exothermic return circuit, the energy storage body sets up in thermal insulation shell, and the energy storage body is piled up by a plurality of energy storage body unit and forms, and the energy storage body unit comprises fused salt box and the fused salt of dispersion filling in the fused salt box, and heat accumulation return circuit, exothermic return circuit laminate mutually with a plurality of energy storage body unit. The invention adopts the high-temperature fused salt solid-liquid phase change energy storage technology, has high energy storage density and high energy storage temperature, thereby having higher thermoelectric conversion efficiency, no need of a fused salt tank, small occupied area and low cost.

Description

Solid-liquid phase change energy storage device for dispersed filling of molten salt

Technical Field

The invention belongs to the field of energy storage, and particularly relates to a solid-liquid phase change energy storage device for dispersed filling of molten salt.

Background

The biggest difficult problem of power grid power supply scheduling is peak shaving. Because the difference of the power load between the peak time of the daytime power utilization and the valley time of the latter night power utilization is large, more power generation is needed during the peak time, and less power generation is needed during the valley time.

The current power supply of China mainly depends on coal-fired thermal power generating units for power generation, while the thermal power generating units cannot be stopped randomly in the operation process, and only the output load of the units can be reduced. Because the peak shaving capacity of the thermal power generating unit is very limited, in the low-ebb period, even if the output load of the unit is tuned to the minimum load of safe operation, the output load of the whole power grid still exceeds the power utilization load. At the moment, the power grid dispatching system is forced to stop part of the unit operation for the power grid safety. However, when a unit is required to stop operating, the steam generation system, the steam pipeline system and the electrical control system of the boiler all enter an abnormal state. And the unit often stops the operation, can bring certain influence to the life of equipment.

In order to ensure the safety of a power grid and the normal operation of a coal-fired thermal power generating unit, an energy storage method is the best peak shaving means, namely, redundant electric energy on the power grid in the later night electricity utilization valley period is converted into energy in other forms for storage, and the stored energy is converted into electric energy to be transmitted to the power grid in the daytime electricity utilization peak period, so that the purpose of peak shaving and valley filling is achieved. The method has multiple purposes, solves the problem of consumption of excess electric energy on a power grid during the off-peak period of power utilization, and can increase the output load of the thermal power generating unit during the peak period of power utilization without increasing the steam generating capacity of the boiler of the thermal power generating unit. Therefore, a series of relevant policies are set by the country, the energy storage technology is treated as an industry, the development target of the energy storage industry is clarified, and the important position of energy storage in the power system is established.

In addition, with the rapid development of non-hydraulic renewable energy power generation (solar photovoltaic power generation and wind power generation), electric energy with unstable output load cannot be timely consumed by a power grid under most conditions, and is only wasted as electricity is abandoned. If energy storage conversion is adopted, the method is the best method for eliminating the electricity abandonment.

Although there are many energy storage methods, according to the prior art, only pumped storage and thermal energy storage can be used as peak shaving energy storage of the power system, and other energy storage methods are not sufficient to take the important role of peak shaving energy storage of the power system.

Pumped storage is the energy storage mode with the highest energy conversion efficiency, but the construction of pumped storage power stations is restricted by natural conditions, so that natural conditions for constructing an upper reservoir and a lower reservoir are required, the investment is large, and the influence on the surrounding environment is also large.

Relatively speaking, the heat energy storage is convenient, and although the thermoelectric conversion efficiency of the heat energy storage is not as high as that of the pumped storage, the heat energy storage is not limited by natural conditions. And with the development of the solar photo-thermal power generation industry, an efficient thermal energy storage technology is also needed to support.

The heat energy storage is also called heat storage because it stores heat energy.

When the thermal energy storage is used as peak shaving energy storage of a power system, high-grade thermal energy needs to be stored in order to improve the thermoelectric conversion efficiency. The higher the temperature of the stored thermal energy, the higher the grade of the thermal energy and the higher the thermoelectric conversion efficiency.

The thermal energy storage is divided into sensible heat storage and phase change latent heat storage (phase change storage for short). Sensible heat storage stores heat energy (heat storage) and releases heat energy (heat release) through temperature changes of an energy storage material, so that the temperature of the energy storage material is constantly changing. According to different states of the energy storage material, the sensible heat energy storage comprises solid sensible heat energy storage and liquid sensible heat energy storage. Phase change energy storage stores heat energy (heat storage) and releases heat energy (heat release) through a heat effect (latent heat) generated by phase change of an energy storage material, and the temperature of the energy storage material is basically kept unchanged before and after phase change. The solid-solid phase change, the solid-liquid phase change and the liquid-gas phase change exist according to the change among different phases of a substance, although the liquid-gas phase change energy storage density of the substance is very large, the volume difference of the substance before and after the liquid-gas phase change is very large, and the pressure of gas (the steam pressure of the substance) at high temperature is very high, which brings great difficulty to engineering application, the solid-solid phase change is generally used for low-temperature energy storage, and the energy storage density of a commonly used solid-solid phase change energy storage material is not too large, so the solid-solid phase change energy storage material is rarely used, and is mainly used for energy storage phase change.

Most common inorganic salts have good thermophysical properties, large mass density, wide sources and proper price, and are suitable for being used as materials for storing heat energy. For example, various nitrates have lower melting points, belong to low-melting-point molten salts, and are characterized in that the liquid nitrates have good fluidity and a larger applicable temperature range, and are suitable for being used as materials for liquid sensible heat energy storage. Inorganic salts such as fluoride salt, chloride salt, carbonate, sulfate and the like have higher melting points and are collectively called high-temperature molten salt, and the high-temperature molten salt is characterized in that the salt has large solid-liquid phase change latent heat and is suitable to be used as a material for high-temperature solid-liquid phase change energy storage.

The sensible heat energy storage technology which adopts liquid salt (namely molten salt) as an energy storage material is widely applied to energy storage devices in solar photo-thermal power generation projects, firstly, solar energy is converted into heat energy to be stored, and then, the stored heat energy is converted into electric energy to be transmitted to a power grid. The molten salt used in the solar photo-thermal power generation project at present is a potassium nitrate-sodium nitrate mixed salt with a low melting point. The liquid mixed salt sensible heat energy storage technology is also applied to a peak regulation energy storage project of a power system, but the application scale is small.

Adopt liquid fused salt sensible heat energy storage, need two fused salt jars of hot salt jar and cold salt jar, the high fused salt of temperature after the splendid attire heat accumulation respectively and the fused salt that the back temperature is low after exothermic, but because the specific heat capacity of liquid fused salt is less relatively, in the operating temperature scope of allowwing, the energy storage density of fused salt is less, so satisfy that the required fused salt volume of certain energy storage scale is just many, therefore the volume of two fused salt jars just will be big, so the area of fused salt jar is just big.

The sensible heat of the molten salt is used for storing energy, the use temperature of the molten salt is far higher than the melting point of the molten salt, and heat storage and heat release can be realized only by a certain temperature change range, so that the temperature of the molten salt is changed all the time. The maximum allowable use temperature of the potassium nitrate-sodium nitrate mixed salt is 565 ℃, and when the temperature is exceeded, the chemical stability is reduced, the potassium nitrate-sodium nitrate mixed salt is easy to decompose and deteriorate, and the service life is shortened. Therefore, the mixed salt of potassium nitrate and sodium nitrate is adopted for energy storage, the stored heat energy is low in grade due to the fact that the energy storage temperature is not too high, the thermoelectric conversion efficiency is only about 35%, and most of the rest heat energy is wasted and lost in the conversion process.

With the continuous development of the solar photo-thermal power generation technology, the scale of the matched energy storage device is larger and larger, and therefore the volume of the molten salt tank is also larger and larger. However, the large-scale molten salt tank has high requirements on the foundation and the foundation, particularly the uneven settlement of the foundation cannot be too large, otherwise the bottom structure of the molten salt tank is damaged, and the consequence that a large amount of molten salt with certain temperature rushes out of the tank is caused, so that a major accident is caused.

From the above, the liquid sensible heat energy storage of the low-melting-point potassium nitrate-sodium nitrate mixed salt is not suitable for large-scale peak shaving energy storage of a power system.

Adopt high temperature fused salt of higher melting point such as fluoride, chlorate, carbonate, sulfate, carry out high temperature solid-liquid phase change energy storage, be used for the large-scale peak regulation energy storage of electric power system, can improve energy storage temperature, thereby improve thermoelectric conversion efficiency, reduce the heat energy loss among the thermoelectric conversion in-process, and the phase change energy storage density of fused salt is big, compare with the liquid sensible heat energy storage of nitrate, under the condition of same energy storage scale, can reduce the quantity of fused salt, thereby the volume of fused salt jar has been reduced, and only need a fused salt jar, can reduce area.

Note: in the field of thermal energy storage, the term "molten salt" is a term, and is called as "molten salt" regardless of whether the salt is solid at low temperature or liquid after being melted by heating. Therefore, inorganic salts having a high melting point, such as fluoride salts, chloride salts, carbonate salts, and sulfate salts, are called "high-temperature molten salts".

However, the physical properties of the high-temperature molten salt are: the volume change at solid-liquid phase change is large, and the thermal conductivity of liquid molten salt is poor. The larger volume change rate increases the cavity in the solidified molten salt body when the molten salt is solidified, influences the heat storage and release rates, reduces the dynamic performance of the heat storage and release processes, and increases the design difficulty of the energy storage device. Therefore, although the solid-liquid phase change energy storage density of the molten salt is high, the heat storage and release method is difficult to solve for practical engineering application, so that no practical engineering application example exists at present.

In addition, the liquid high-temperature molten salt is more corrosive to the current common metal materials, so that the large molten salt tank containing the high-temperature molten salt has high requirements on tank body materials, is not only corrosion resistant, but also has corresponding strength at high temperature, and therefore the high-temperature molten salt tank is made of high-temperature resistant and corrosion resistant metal plates. However, the material used for producing the metal plate is only in the research and test stage at present, and most of the selected test materials adopt refractory nonferrous metals as alloys, so that the price is high, and the difference from the actual application level of engineering is large. So that at present, no engineering material (metal plate) which can be used for manufacturing a large-scale high-temperature molten salt tank can be adopted.

In order to solve the above problems, researchers have proposed a high-temperature fused salt phase change energy storage material with a composite structure and a capsule micro-encapsulation high-temperature fused salt phase change energy storage material, and have performed tests. The two structures can only solve the packaging problem of high-temperature molten salt, and the prepared composite structure phase-change energy storage material has low content of the molten salt, so the energy storage density of the material is also low.

The high-temperature molten salt phase change energy storage material with the composite structure is only in a test stage at present, and even if the test effect achieves the expected purpose, the heat storage and heat release method of the energy storage material is not easy to solve.

From the above, in a large-scale energy storage device required by a power system aiming at peak shaving, if a high-temperature molten salt phase change energy storage technology is adopted, although the energy storage temperature is high, the thermoelectric conversion efficiency is higher, the consumption of molten salt can be reduced, and the heat energy loss can be reduced, only one molten salt tank is needed, the occupied area is small, and the like, the high-temperature molten salt heat storage and heat release method is difficult to solve due to the fact that high-temperature-resistant and corrosion-resistant metal plates required by the existing large-scale high-temperature molten salt tank cannot be solved, and the characteristics of large volume change and poor heat conductivity of liquid molten salt exist during solid-liquid phase change of the high-temperature molten salt, so that the high-temperature molten salt solid-liquid phase change energy storage technology is not mature in the aspect of.

In summary, the existing thermal energy storage technology using molten salt as an energy storage material has the following disadvantages when applied to large-scale peak shaving energy storage of a power system:

1. adopt the liquid sensible heat energy storage of low melting point potassium nitrate-sodium nitrate mixed salt, because receive the restriction of the highest allowable temperature of fused salt, the energy storage temperature can not be too high, cause thermoelectric conversion efficiency lower, lead to most heat energy to become useless calorific loss in thermoelectric conversion process, and whole energy storage system needs two large-scale molten salt jars of hot salt jar and cold salt jar, still because the energy storage density of fused salt sensible heat energy storage is lower, so the fused salt quantity is big, not only the volume of molten salt jar is very big, the cost of molten salt jar is high, area is big, and the acquisition cost of fused salt is big, consequently, the investment of whole system infrastructure is very high. In addition, the large molten salt tank has high requirements on the foundation and the foundation, and if the uneven settlement of the foundation is too large, the molten salt tank can be damaged, and serious accidents are caused.

2. If the high-temperature molten salt solid-liquid phase change energy storage is adopted, although the high-temperature molten salt solid-liquid phase change energy storage has high energy storage temperature, the thermoelectric conversion efficiency is higher, the consumption of the molten salt can be reduced, only one molten salt tank is needed, the occupied area is small, the investment is low and the like, but the high-temperature resistant and corrosion resistant metal plate which is needed for manufacturing the high-temperature molten salt tank at present cannot be solved, the volume change is large when the high-temperature molten salt has the solid-liquid phase change energy storage, the heat conductivity of the liquid molten salt is poor and the like, so that the heat storage and release method of the high-temperature molten salt is difficult to solve, and the high-temperature molten salt solid-liquid phase change. Even if the high-temperature molten salt is made into the energy storage material with the composite structure, the energy storage density is low, and the heat storage and release method is not easy to solve, so that the high-temperature molten salt can not be applied to engineering practice at present.

In order to meet the requirement of large-scale peak shaving energy storage of an electric power system, the phase change energy storage technology is listed as an industry prospective and key core technology to be involved in the prior art.

Disclosure of Invention

The invention aims to provide a solid-liquid phase change energy storage device which adopts fused salt solid-liquid phase change energy storage and has high energy storage temperature, thereby having higher thermoelectric conversion efficiency, large energy storage density, simple heat storage and heat release method, small occupied area and low cost, does not need a fused salt tank made of high-temperature-resistant and corrosion-resistant metal plates and dispersedly fills fused salt, and overcomes the defects of the prior art.

In order to achieve the purpose, the technical scheme of the invention is as follows: the utility model provides a solid-liquid phase change energy memory of dispersion filling fused salt, includes thermal insulation shell, the energy storage body, heat accumulation return circuit, exothermic return circuit, the energy storage body sets up in the thermal insulation shell, the energy storage body is piled up by a plurality of energy storage body unit and builds up and form, the energy storage body unit is in by fused salt box and dispersion filling fused salt in the fused salt box is constituteed, the heat accumulation return circuit with exothermic return circuit and a plurality of the energy storage body unit is laminated mutually.

In the above technical scheme, the heat storage loop is an electric heating loop attached to the plurality of energy storage body units, and a heating working medium in the electric heating loop is electric current.

In the above technical scheme, the heat storage loop is a heating pipeline attached to the plurality of energy storage body units, and the heating working medium in the heating pipeline is liquid, gas or solid particles.

In the above technical scheme, the heat release loop is a heat release pipeline attached to the plurality of energy storage body units, and the heat release working medium in the heat release pipeline is liquid, gas or solid particles.

In the technical scheme, gaps among the plurality of energy storage body units after being stacked are filled with loose solid materials.

In the above technical solution, the heating pipeline or the heat release pipeline and the energy storage units are filled with a filler capable of conducting heat in a gap between the two units to make the two units fit with each other.

In the technical scheme, the heat storage loop is a plurality of the heat storage body units are stacked to leave a heating channel for gas flowing, heating working media in the heating channel are gas, and the heat preservation shell is provided with a heating gas inlet and a heating gas outlet.

In the above technical scheme, the heat release loop is a heat release channel for gas flowing reserved between the plurality of energy storage body units after being stacked, the heat release working medium in the heat release channel is gas, and the heat release gas inlet and the heat release gas outlet are arranged on the heat insulation shell.

In the above technical scheme, the molten salt dispersedly filled in the molten salt box is a salt of one single component of fluoride salt, chloride salt, carbonate and sulfate, or a mixed salt of two or more of the components.

The solid-liquid phase change energy storage device for dispersedly filling the molten salt has the beneficial effects that:

(1) the invention provides a novel heat energy storage device for large-scale peak regulation energy storage of an electric power system, which adopts a high-temperature fused salt solid-liquid phase change energy storage technology, wherein high-temperature fused salt is dispersedly filled in a plurality of fused salt boxes to form energy storage body units, and the plurality of energy storage body units are stacked in a heat insulation shell to form an energy storage body, so that a fused salt tank made of high-temperature-resistant and corrosion-resistant metal plates is not needed, an energy storage material with a composite structure is also not needed to be made of the high-temperature fused salt, and the heat storage and release methods are simple, so that the high-temperature fused salt solid-liquid phase change energy storage technology can be conveniently applied in engineering practice.

(2) Compared with the existing liquid sensible heat energy storage of potassium nitrate-sodium nitrate mixed salt, the liquid sensible heat energy storage system has the advantages of high energy storage temperature, higher thermoelectric conversion efficiency, reduction of heat energy loss in the thermoelectric conversion process, high energy storage density, small occupied area and low cost, and two molten salt tanks, namely a hot salt tank and a cold salt tank, are omitted.

Drawings

FIG. 1 is a schematic diagram of a solid-liquid phase change energy storage device for dispersed molten salt filling according to the present invention;

FIG. 2 is a schematic diagram of a solid-liquid phase change energy storage device for dispersed filling of molten salt according to the present invention, in which the heat storage loop is an electric heating loop and the heat release loop is a heat release pipeline;

FIG. 3 is a schematic diagram of a solid-liquid phase change energy storage device for dispersed molten salt filling according to the present invention, in which a heat storage loop is a heating pipeline and a heat release loop is a heat release pipeline;

FIG. 4 is a schematic top view of a solid-liquid phase change energy storage device for dispersed filling of molten salt according to the present invention, in which a heat storage loop is a heating channel for gas flowing reserved between a plurality of energy storage units, a heat preservation housing has a heating gas inlet and a heating gas outlet, and a heat release loop is a heat release pipeline;

FIG. 5 is a schematic top view of a solid-liquid phase change energy storage device for molten salt dispersion filling according to the present invention, in which the heat storage loop is an electric heating loop, and the heat release loop is a heat release channel for gas flowing reserved between a plurality of energy storage units;

FIG. 6 is a schematic top view of a solid-liquid phase change energy storage device for molten salt dispersion filling according to the present invention, in which a heat storage loop is a heating pipeline, and a heat release loop is a heat release channel for gas flowing reserved between a plurality of energy storage units;

fig. 7 is a schematic diagram of an energy storage body cell.

Wherein, 1, a heat preservation shell; 2. an energy storage body; 3. a heat storage loop; 4. a heat release circuit; 5. an electrical heating circuit; 6. a heat release pipe; 7. heating the pipeline; 8. a heating channel; 9. a heated gas inlet; 10. a heated gas outlet; 11. a heat release channel; 12. a heat release gas inlet; 13. a heat release gas outlet; 2-1, energy storage body unit; 2-1-1. molten salt box; 2-1-2. molten salt; 2-1-3, groove; 2-1-4. through holes; 2-1-5. molten salt filling opening; 2-1-6, and a cover.

Detailed Description

The invention is further described below with reference to the accompanying drawings and the examples given.

As shown in fig. 1, 2, 3, 4, 5, 6, and 7, a solid-liquid phase change energy storage device filled with molten salt dispersedly comprises a thermal insulation shell 1, an energy storage body 2, a heat storage loop 3, and a heat release loop 4. The energy storage body 2 is arranged in the heat preservation shell 1, the energy storage body 2 is formed by stacking a plurality of energy storage body units 2-1, the energy storage body units 2-1 are formed by molten salt boxes 2-1-1 and molten salt 2-1-2 filled in the molten salt boxes 2-1-1 in a dispersing mode, the heat storage loop 3 and the heat release loop 4 are attached to the energy storage body units 2-1, and the purpose of attaching is to transfer heat energy between a heating working medium in the heat storage loop 3 and a heat release working medium in the heat release loop 4 and the energy storage body units 2-1.

As shown in fig. 2, the heat storage loop 3 is an electric heating loop 5, the part of the electric heating loop 5 attached to the energy storage unit 2-1 is an electric heating element (such as a resistance heating element, an electric heating radiation heating element, and an electric induction heating element), and the heating working medium in the electric heating loop 5 is current. The heat release loop 4 is a heat release pipeline 6, and the heat release working medium in the heat release pipeline 6 is liquid, gas or solid particles.

The energy storage device shown in fig. 2 is used in a situation where electric energy is used as a heat storage energy source and a high-temperature heat source is required. When heat is stored, current is introduced into the electric heating loop 5, when the current flows through the electric heating element, electric energy is converted into heat energy (heat), the heating temperature of the electric heating element is increased, the molten salt 2-1-2 in the molten salt box 2-1-1 is heated, when the temperature of the molten salt 2-1-2 is higher than the melting point of the molten salt, the molten salt 2-1-2 is gradually melted from a solid state to a liquid state (namely solid-liquid phase change occurs), the energy storage device stores heat (stores heat energy), and the heating is stopped after the molten salt 2-1-2 is melted. The energy storage body unit 2-1 is arranged in the heat preservation shell 1, and heat energy loss can be reduced. When the heat-stored energy storage device releases heat, heat release working medium (liquid, gas or solid particles) with lower temperature flows through the heat release pipeline 6 by adopting a conveying machine (a pump, a compressor or an air flow conveying device respectively), because the heat release pipeline 6 is jointed with the energy storage body unit 2-1, the fused salt 2-1-2 in the energy storage body unit 2-1 transfers the stored heat energy to the heat release working medium in the heat release pipeline 6, and the temperature of the heat release working medium is increased after the heat release working medium absorbs the heat energy. The heat release working medium after absorbing the heat energy is introduced into a thermoelectric conversion unit (such as a steam generator and a steam turbine unit or other heat engine generator units), the heat energy absorbed by the heat release working medium is converted into electric energy, and the heat release working medium after absorbing the heat energy can also be introduced into a heating device needing the heat energy for directly heating other articles. Under the drive of the conveying machine, the heat release working medium with the reduced temperature from the thermoelectric conversion unit or the heating device returns to the heat release pipeline 6 for circulation, continues to absorb heat energy, and then enters the thermoelectric conversion unit or the heating device. The molten salt 2-1-2 in the molten salt box 2-1-1 is gradually solidified into a solid state (namely liquid-solid phase change occurs) after releasing heat energy, the energy storage device releases heat (releases heat energy), and the heat release is stopped after the molten salt 2-1-2 is solidified.

As shown in fig. 3, the heat storage loop 3 is a heating pipeline 7, the heating working medium in the heating pipeline is liquid, gas or solid particles, the heat release loop 4 is a heat release pipeline 6, and the heat release working medium in the heat release pipeline 6 is liquid, gas or solid particles.

The energy storage device shown in fig. 3 is used in a case where a high-temperature heat source is required, using the heat energy contained in the direct heat source as the heat storage energy source. During heat storage, a heating working medium (liquid, gas or solid particles) heated by a direct heat source and having a temperature higher than the melting point of the molten salt 2-1-2 is introduced into a heating pipeline 7, the heating working medium transfers heat energy to the energy storage body unit 2-1, the temperature of the molten salt 2-1-2 in the energy storage body unit 2-1 rises after the heat energy is absorbed, when the temperature of the molten salt 2-1-2 is higher than the melting point of the molten salt, the molten salt 2-1-2 is gradually melted from a solid state to a liquid state (namely solid-liquid phase change occurs), an energy storage device stores heat (stores heat energy), a conveying machine (respectively a pump, a compressor and an air flow conveying device) is adopted to enable the heating working medium with the reduced temperature from the heating pipeline 7 to be sent to be heated by the direct heat source, then the heating working medium enters the heating pipeline 7 to circulate to, and stopping heating after the molten salt 2-1-2 is melted. When the stored energy storage device releases heat, the same heat release method as that in the energy storage device shown in fig. 2 is adopted, heat release working substances (liquid, gas and solid particles) with lower temperature flow through the heat release pipeline 6 by adopting a conveying machine (respectively a pump, a compressor or an air flow conveying device) to release heat (release heat energy), and the heat release is stopped after the molten salt 2-1-2 is solidified.

As shown in fig. 4, the heat storage loop 3 is a heating channel 8 for gas to flow, which is reserved between a plurality of energy storage body units 2-1 after being stacked, the heating working medium in the heating channel 8 is gas, the heat preservation shell 1 is provided with a heating gas inlet 9 and a heating gas outlet 10, the heat release loop 4 is a heat release pipeline 6, and the heat release working medium in the heat release pipeline 6 is liquid, gas or solid particles.

The energy storage device shown in fig. 4 is used for the occasion that the heat energy contained in the atmospheric pressure or micro-pressure gas with the temperature higher than the melting point of the molten salt 2-1-2 is used as the heat storage energy source and a high-temperature heat source is needed. During heat storage, a heating working medium (namely, normal pressure or micro pressure gas) with the temperature higher than the melting point of the molten salt 2-1-2 enters the heating channel 8 from the heating gas inlet 9, flows towards the heating gas outlet 10 in the heating channel 8, contacts the energy storage body unit 2-1 when flowing in the heating channel 8, transfers heat energy to the energy storage body unit 2-1, the temperature of the molten salt 2-1-2 in the energy storage body unit 2-1 is increased after absorbing the heat energy, when the temperature of the molten salt 2-1-2 is higher than the melting point of the molten salt, the molten salt 2-1-2 is gradually melted from a solid state to a liquid state (namely, solid-liquid phase change occurs), the energy storage device stores heat energy, the heating working medium entering the heating channel 8 can flow in the heating channel 8 by adopting a fan drive or other drive modes, and stopping heating after the molten salt 2-1-2 is melted. When the stored energy storage device releases heat, the same heat release method as that in the energy storage device shown in fig. 2 is adopted, heat release working medium (liquid, gas or solid particles) with lower temperature flows through the heat release pipeline 6 by adopting conveying machinery (respectively a pump, a compressor and an air flow conveying device) to release heat (release heat energy), and the heat release is stopped after the molten salt 2-1-2 is solidified.

As shown in fig. 5, the heat storage loop 3 is an electric heating loop 5, the part of the electric heating loop 5 attached to the energy storage body unit 2-1 is an electric heating element (such as a resistance heating element, an electric heating radiation heating element, and an electric induction heating element), and the heating working medium in the electric heating loop 5 is current. The heat release loop 4 is a heat release channel 11 which is reserved among the plurality of energy storage body units 2-1 after being stacked and used for gas flowing, a heat release working medium in the heat release channel 11 is gas, and the heat release gas inlet 12 and the heat release gas outlet 13 are arranged on the heat insulation shell 1.

The energy storage device shown in fig. 5 is used in a case where electric energy is used as a heat storage energy source and a high-temperature gas is used as a heat source. During heat storage, the same heat storage method as that in the energy storage device shown in fig. 2 is adopted, current is introduced into the electric heating loop 5, electric energy is converted into heat energy (heat), the molten salt 2-1-2 in the molten salt box 2-1-1 is heated, when the temperature of the molten salt 2-1-2 is higher than the melting point of the molten salt, the molten salt 2-1-2 is gradually melted from a solid state to a liquid state (namely solid-liquid phase change occurs), the energy storage device stores heat (stores heat energy), and heating is stopped after the molten salt 2-1-2 is melted. When the heat-stored energy storage device releases heat, heat-releasing working medium (namely normal-pressure or micro-pressure gas) with lower temperature enters the heat-releasing channel 11 from the heat-releasing gas inlet 12, the heat-releasing working medium flows towards the heat-releasing gas outlet 13 in the heat-releasing channel 11, the heat-releasing working medium is contacted with the energy storage body unit 2-1 when flowing in the heat-releasing channel 11, the molten salt 2-1-2 in the energy storage body unit 2-1 transfers the stored heat energy to the heat-releasing working medium, the temperature of the heat-releasing working medium is increased after the heat energy is absorbed, and the heat-releasing working medium after the heat energy is absorbed is introduced into a device which needs to adopt high-temperature gas as a heat source to heat other articles. The heat release working medium entering the heat release channel 11 can be driven by a fan or other driving modes to enable the heat release working medium to flow in the heat release channel 11 to release heat (release heat energy), and the heat release is stopped after the molten salt 2-1-2 is solidified.

As shown in fig. 6, the heat storage loop 3 is a heating pipeline 7, the heating working medium in the heating pipeline 7 is liquid, gas or solid particles, the heat release loop 4 is a heat release channel 11 reserved among a plurality of energy storage body units 2-1 after being stacked for gas flowing, the heat release working medium in the heat release channel 11 is gas, and the heat insulation shell 1 is provided with a heat release gas inlet 12 and a heat release gas outlet 13.

The energy storage device shown in fig. 6 is used in a case where heat energy contained in a direct heat source is used as a heat storage energy source and a high-temperature gas is used as a heat source. During heat storage, the same heat storage method as that in the energy storage device shown in FIG. 3 is adopted, a heating working medium (liquid, gas or solid particles) which is heated by a direct heat source and has the temperature higher than the melting point of the molten salt 2-1-2 is introduced into the heating pipeline 7 to heat the molten salt 2-1-2 in the energy storage body unit 2-1, when the temperature of the fused salt 2-1-2 is higher than the melting point of the fused salt, the fused salt 2-1-2 is gradually melted from the solid state to the liquid state (namely solid-liquid phase change occurs), the energy storage device stores heat (stores heat energy), the conveying machinery (respectively a pump, a compressor and an air flow conveying device) is adopted to ensure that the heating working medium with the reduced temperature from the heating pipeline 7 is sent to be heated by a direct heat source, and then the molten salt enters a heating pipeline 7 for circulation, the molten salt is continuously heated, and the heating is stopped after the molten salt 2-1-2 is melted. When the stored energy storage device releases heat, the same heat release method in the stored energy storage device shown in fig. 5 is adopted, heat release working medium (namely normal pressure or micro pressure gas) with lower temperature enters the heat release channel 11 from the heat release gas inlet 12, the heat release working medium flows to the heat release gas outlet 13 in the heat release channel 11, the fused salt 2-1-2 in the energy storage body unit 2-1 transfers the stored heat energy to the heat release working medium, and the heat release working medium absorbing the heat energy is introduced into a device which needs to adopt high temperature gas as a heat source for heating other articles. The heat release working medium entering the heat release channel 11 can be driven by a fan or other driving modes to enable the heat release working medium to flow in the heat release channel 11 to release heat (release heat energy), and the heat release is stopped after the molten salt 2-1-2 is solidified.

As shown in fig. 7, the energy storage unit 2-1 is composed of a molten salt box 2-1-1 and molten salts 2-1-2 dispersedly filled in the molten salt box 2-1-1, the molten salt box 2-1-1 is made of a heat conductive metal material or a non-metal material, the metal material is an alloy composed of two or more elements of iron, carbon, silicon, aluminum, manganese, chromium, nickel, molybdenum, vanadium and cobalt, and if the metal material is adopted, a non-metal film coating layer can be arranged on the inner wall of the energy storage unit, so that the metal material is not in direct contact with the molten salts, and corrosion of the molten salts to the metal material at high temperature is avoided. In order to make the energy storage body unit 2-1 fit with the heating pipeline 7 and the heat release pipeline 6 in fig. 2, 3, 4 and 6, a plurality of grooves 2-1-3 are reserved on the outer wall of the fused salt box 2-1-1 according to the section shapes and sizes of the heating pipeline 7 and the heat release pipeline 6, the heating pipeline 7 and the heat release pipeline 6 are embedded in the grooves 2-1-3, or a plurality of through holes 2-1-4 are reserved at the lower part of the fused salt box 2-1-1, and the heating pipeline 7 and the heat release pipeline 6 pass through the through holes 2-1-4. The outer wall of the molten salt box 2-1-1 can also be provided with a groove 2-1-3 and a through hole 2-1-4. The grooves 2-1-3 and the through holes 2-1-4 can be horizontally arranged, vertically arranged or crossly arranged according to different heating working mediums and heat release working mediums in the heating pipeline 7 and the heat release pipeline 6 so as to obtain better heat transfer effect.

For the electric heating circuit 5 in fig. 2 and 5, the electric heating element is attached to the outer wall of the molten salt box 2-1-1 to transfer heat energy. The heating channel 8 in fig. 4 and the heat release channel 11 in fig. 5 and 6 are spaces for gas to flow left between the energy storage body units 2-1 after being stacked, so that when a heating working medium or a heat release working medium flows in the heating channel 8 or the heat release channel 11, the heating working medium or the heat release working medium directly contacts with the energy storage body units 2-1 to transfer heat energy.

The upper part of the molten salt box 2-1-1 is provided with a molten salt filling opening 2-1-5, when the molten salt 2-1-2 is filled into the molten salt box 2-1-1, the molten salt box is not filled with the molten salt, and a certain space is reserved to prevent solid molten salt from overflowing the molten salt box due to volume increase after the solid molten salt is heated and melted. A cover 2-1-6 can also be arranged on the fused salt filling opening 2-1-5, and after the fused salt 2-1-2 is filled in the fused salt box 2-1-1, the fused salt filling opening 2-1-5 is covered by the cover 2-1-6.

The energy storage device dispersedly fills the molten salt 2-1-2 in the plurality of molten salt boxes 2-1-1, even if the thermal conductivity of the liquid molten salt is poor, and the volume of the liquid molten salt shrinks during solidification to generate a plurality of cavities in the solidified molten salt, the phenomenon is not obvious because the amount of the molten salt in each molten salt box 2-1-1 is not large, and the solid molten salt and the liquid molten salt before and after phase change are always in contact with the inner wall of the molten salt box 2-1-1, so the thermal resistance between the molten salt 2-1-2 and the molten salt box 2-1-1 is small, and the influence on the heat energy transfer is small.

In fig. 2, 3, 4, and 6, the heating working medium in the heating pipeline 7 and the heat releasing working medium in the heat releasing pipeline 6 are the following liquids: can be molten liquid metal (such as sodium, potassium, sodium-potassium alloy, or alloy composed of two or more of lead, tin, bismuth and antimony), or inorganic salt with melting point lower than the lowest working temperature in the heating process and the heat release process; the gas used was: carbon dioxide, nitrogen, methane, inert gas, or a mixed gas of two or more of the carbon dioxide, the nitrogen, the methane and the inert gas, or high-temperature process gas in the chemical production process; the solid particulate material employed: silicon carbide, graphite, magnesia, alumina, silica, ceramic particles or a mixture of two or more of the above, the particle size of the solid particles is in the range of 0.01-1000 μm, and the solid particles have good heat transfer performance and air flow transport property.

Heating medium in the heating channel 8 in fig. 4: high-temperature flue gas discharged by an industrial furnace, high-temperature gas discharged by a burner, or normal-pressure (or micro-pressure) high-temperature tail gas discharged by an industrial process.

Heat release working medium in heat release channel 11 in fig. 5 and 6: air, nitrogen, carbon dioxide, or atmospheric (or micropressure) process gases that require heating during industrial processes.

The heating pipeline 7 and the heat release pipeline 6 in fig. 3 may be the same group of pipelines, and serve as the heating pipeline 7 for heat storage, and the heating working medium is introduced into the pipeline, and serve as the heat release pipeline 6 for heat release, and the heat release working medium is introduced into the pipeline.

The heating channel 8 in fig. 4 and the heat releasing channel 11 in fig. 5 and 6 may be the same set of channels disposed in a set of energy storage device, and serve as the heating channel 8 during heat storage, and the heating working medium is introduced into the channels, and serve as the heat releasing channel 11 during heat release, and the heat releasing working medium is introduced into the channels.

The heat storage loop 3 can be provided with an electric heating loop 5, a heating pipeline 7 and a heating channel 8, and can store heat in various heating modes; the heat release loop 4 of the invention can be provided with the heat release pipeline 6 and the heat release channel 11, and can release heat by adopting various heat release modes.

The molten salt 2-1-2 dispersedly filled in the molten salt box 2-1-1 is one single component salt of fluoride salt, chloride salt, carbonate and sulfate, or a mixed salt of two or more components of the fluoride salt, the chloride salt, the carbonate and the sulfate, wherein part of metal oxide or hydroxide can be contained, the salt of each component has different melting points and latent heat of phase change, the melting points of the mixed salt of two or more components can be adjusted, and the salt of the corresponding component can be selected as an energy storage material according to the energy storage requirement.

The heating pipeline 7 or the heat release pipeline 6 in fig. 2, 3, 4, and 6 is attached to the energy storage units 2-1 by direct contact therebetween, or by filling a gap at the contact therebetween with a thermally conductive filler.

In fig. 2 and 3, a certain gap must exist between a plurality of energy storage body units 2-1 (including between the energy storage body unit 2-1 and the heat preservation shell 1) after being stacked, and in order to reduce the heat energy loss caused by the convection of air in the gap with the outside breathing at high temperature, the gap can be filled with loose solid materials.

The molten salt 2-1-2 in the energy storage body unit 2-1 shown in fig. 7 may be entirely phase-changed or partially phase-changed in the heat storage process and the heat release process according to the need of the heat storage amount and the heat release amount.

The invention can be used for peak regulation energy storage of an electric power system, can also be used for heat energy storage in a solar photo-thermal power generation project, or heat energy storage in other heat energy power generation projects, can also be used as energy storage in other projects needing heat sources, or high-temperature waste heat recovery energy storage in industrial processes, and can also be used as an energy storage heat source of a centralized heating system.

In addition, in consideration of safety, the nuclear power units in operation in China do not bear the peak regulation task of the power grid at present, but because the installed capacities of the nuclear power units are large, in order to ensure the safety and reliability of the power grid, partial conditional areas exist, and the nuclear power stations adopt a 'nuclear storage integration' operation mode, namely corresponding pumped storage power stations are constructed in a matched mode to bear the peak regulation task for the nuclear power units. The invention can also be used as auxiliary energy storage for enabling the nuclear power unit to operate without peak regulation.

Claims (10)

1. The utility model provides a solid-liquid phase change energy memory of dispersed filling fused salt which characterized in that: the device comprises a heat preservation shell, an energy storage body, a heat storage loop and a heat release loop, wherein the energy storage body is arranged in the heat preservation shell and is formed by piling up a plurality of energy storage body units, the energy storage body units are filled in a molten salt box and dispersed in the molten salt box to form molten salt, and the heat storage loop and the heat release loop are attached to the energy storage body units.

2. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 1, wherein: the heat storage loop is an electric heating loop which is attached to the energy storage body units, and a heating working medium in the electric heating loop is current; or the heat storage loop is a heating pipeline jointed with the energy storage body units, and the heating working medium in the heating pipeline is liquid, gas or solid particles; or the heat storage loop is a plurality of the energy storage body units are stacked to form a heating channel for gas flowing, the heating medium in the heating channel is gas, and the heat preservation shell is provided with a heating gas inlet and a heating gas outlet.

3. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 1, wherein: the heat release loop is a heat release pipeline jointed with the energy storage body units, and a heat release working medium in the heat release pipeline is liquid, gas or solid particles; or the heat release loop is a heat release channel which is reserved among the plurality of energy storage body units after being stacked and used for gas flowing, the heat release working medium in the heat release channel is gas, and the heat release gas inlet and the heat release gas outlet are formed in the heat insulation shell.

4. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 1, wherein: and loose solid materials are filled in gaps among the plurality of energy storage body units after the energy storage body units are stacked.

5. The solid-liquid phase change energy storage device for dispersed filling of molten salt according to claim 2 or 3, characterized in that: the heating pipeline or the heat release pipeline and the energy storage body units are filled with heat-conducting fillers in gaps at the contact positions of the heating pipeline or the heat release pipeline and the energy storage body units so that the heating pipeline or the heat release pipeline and the energy storage body units are jointed.

6. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 1, wherein: the molten salt filled in the molten salt box in a dispersing way is a single-component salt of fluoride salt, chloride salt, carbonate and sulfate or a mixed salt of two or more of the fluoride salt, the chloride salt, the carbonate and the sulfate.

7. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 1, wherein: the heat storage loop is a heating pipeline jointed with the energy storage body units, a heating working medium in the heating pipeline is liquid, or gas, or solid particles, and/or the heat release loop is a heat release pipeline jointed with the energy storage body units, and the heat release working medium in the heat release pipeline is liquid, or gas, or solid particles; the heating pipeline and the heat release pipeline are two groups of pipelines or the same group of pipelines; when the pipelines are the same group, the pipelines are used as heating pipelines during heat storage, heating working media are introduced into the pipelines, and the pipelines are used as heat release pipelines during heat release, and heat release working media are introduced into the pipelines; in order to make the energy storage body unit be attached to the heating pipeline and the heat release pipeline, a plurality of grooves are reserved on the outer wall of the molten salt box according to the shapes and the sizes of the sections of the heating pipeline and the heat release pipeline, the heating pipeline and the heat release pipeline are embedded in the grooves, or a plurality of through holes are reserved at the lower part of the molten salt box, and the heating pipeline and the heat release pipeline pass through the through holes; or the outer wall of the molten salt box is provided with a groove and a through hole; the grooves and the through holes are horizontally arranged, vertically arranged or crossly arranged according to different heating working mediums and heat release working mediums in the heating pipeline and the heat release pipeline so as to obtain better heat transfer effect.

8. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 1, wherein: the heat storage loop is a heating channel for gas flowing reserved among the energy storage body units after the energy storage body units are stacked, a heating working medium in the heating channel is gas, and a heating gas inlet and a heating gas outlet are formed in the heat preservation shell; the heat release loop is a heat release channel which is reserved among the energy storage body units after the energy storage body units are stacked and used for gas flowing, a heat release working medium in the heat release channel is gas, and the heat insulation shell is provided with a heat release gas inlet and a heat release gas outlet; the heating channel and the heat release channel are arranged in a set of energy storage device for the same group of channels, the heating channel is used as the heating channel during heat storage, a heating working medium is introduced into the channel, the heat release channel is used as the heat release channel during heat release, and the heat release working medium is introduced into the channel.

9. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 2, wherein: heating working medium in the heating pipeline, wherein the adopted liquid is molten liquid metal, is sodium, potassium or sodium-potassium alloy, or alloy consisting of two or more of lead, tin, bismuth and antimony, or inorganic salt with the melting point lower than the lowest working temperature in the heating process and the heat release process; the gas used was: carbon dioxide, nitrogen, methane, inert gas, or a mixed gas of two or more of the carbon dioxide, the nitrogen, the methane and the inert gas, or high-temperature process gas in the chemical production process; the solid particulate material employed: silicon carbide, graphite, magnesia, alumina, silicon dioxide, ceramic particles or a mixture of two or more of the silicon carbide, the graphite, the magnesia, the alumina, the silicon dioxide and the ceramic particles, the granularity of the solid particles is within the range of 0.01-1000 μm, and the solid particles have better heat transfer performance and air flow conveying characteristic; heating working medium in the heating channel: high-temperature flue gas discharged by an industrial furnace, high-temperature gas discharged by a burner, or normal-pressure or micro-pressure high-temperature tail gas discharged by an industrial process.

10. The solid-liquid phase change energy storage device for dispersedly filling molten salt according to claim 3, wherein: the heat release working medium in the heat release pipeline adopts the following liquid: can be molten liquid metal, which is sodium, potassium or sodium-potassium alloy, or alloy composed of two or more of lead, tin, bismuth and antimony, or inorganic salt with melting point lower than the lowest working temperature in the heating process and the heat release process; the gas used was: carbon dioxide, nitrogen, methane, inert gas, or a mixed gas of two or more of the carbon dioxide, the nitrogen, the methane and the inert gas, or high-temperature process gas in the chemical production process; the solid particulate material employed: silicon carbide, graphite, magnesia, alumina, silicon dioxide, ceramic particles or a mixture of two or more of the silicon carbide, the graphite, the magnesia, the alumina, the silicon dioxide and the ceramic particles, the granularity of the solid particles is within the range of 0.01-1000 μm, and the solid particles have better heat transfer performance and air flow conveying characteristic; the heat release working medium in the heat release channel is air, nitrogen or carbon dioxide, or normal pressure or micro pressure process gas which needs to be heated in the industrial production process.

Images