CZ2023173A3 - System for storage and transfer of heat with solid bulk material - Google Patents

Abstract

The heat storage and transfer system includes at least one heat source for generating thermal energy; high-temperature heat storage with bulk refractory material (1) filling the high-temperature storage space (14) for storing the generated thermal energy; at least one heat consumption system for utilizing stored thermal energy; and a heat transfer mechanism for transferring heat from the heat source to the high temperature heat storage and from the high temperature heat storage to the heat consumption system. The heat transfer mechanism is a closed gas circuit connecting the heat source, high-temperature heat storage and the heat consumption system. The high-temperature heat storage is partially covered by a supporting inner jacket (3). The bulk refractory material (1) comprises a fraction of particles with a sphericity in the range of 0.4 to 1 and an average particle size in the range of 0.5 to 20 mm. The volume ratio of the largest and smallest particles is a maximum of 5:1. The load-bearing inner shell (3) is sheathed with an outer heat-insulating shell (5) so that between the load-bearing inner shell (3) and the outer heat-insulation shell (5) there is a gas gap (4.1) for the recovery of heat losses from the high-temperature heat storage passing through the supporting inner shell (3). The gas gap (4.1) together with the connecting gas channel (4.3) connects the high-temperature heat storage with at least one technological space (4.2), which is further connected to at least one heat consumption system. The hot gas channel (7) connects the high-temperature heat storage with at least one heat source. The subject of the invention is also a method of storing and transferring heat using the mentioned system.

Description

System for storage and transfer of heat with solid bulk material

Field of technology

This invention relates to a system for storing and transferring heat in a high-temperature heat storage facility where thermal energy is bound in a solid bulk material.

Current state of the art

In the international patent application WO 2020183063 A1, a system and corresponding method for storing and transferring heat is described (here the reference marks belong to WO 2020183063 A1). Said system (100, 300, 400) includes at least one resistor (101, 301, 401) for generating thermal energy from electrical energy; at least one heat storage (102, 302, 402) with a solid material (e.g. sand, stone or gravel) for storing the generated heat energy, preferably stored underground and for storing energy up to a temperature of 1200 °C; and a heat transfer mechanism (103, 303, 403) for transferring heat from the heat storage (102, 302, 402) to the heat consumption system (104, 304, 404) for further use. The resistor (101) can be arranged in the heat storage (102) or outside it. The heat transfer mechanism (103, 303, 403) is either a closed gas circuit (first embodiment of the state of the art) or a thermosiphon system with multiple pipes closed at both ends (second embodiment of the state of the art). The heat storage (102, 302, 402) includes (e.g., stainless steel) pipes arranged in a solid material for gas transport.

In the first embodiment, the closed gas circuit transfers heat from and to the storage (102, 302, 402) of heat, e.g. by means of nitrogen at a pressure of 1 to 50 bar and preferably with the help of a two-way fan. In this embodiment, the gas is routed through tubes in the heat storage (102, 302, 402). In the second embodiment, the thermosiphon system can include thermosiphon tubes filled with liquid up to a maximum of 25% of their volume, e.g. vertically arranged stainless steel thermosiphon tubes filled in the lower part with water, which after heating can completely turn into steam, possibly even supercritical steam, rising to the upper part tubing. Optionally, said system includes a secondary heat transfer circuit (312, 412) and/or a secondary heat storage (313, 413). Optionally, the system includes an electrical power generator to generate power from fluctuating sources or excess power grid capacity, such as a solar panel, wind turbine, tidal power plant, or an overloaded power grid. The storage (102, 302, 402) of heat can be covered with an insulating layer with a material of low thermal conductivity, e.g. artificial aggregate with a thermal conductivity below 0.3 W/mK.

The disadvantage of the mentioned system with a closed gas circuit inside the storage space, as a heat transfer mechanism, is the need to provide a heat exchange surface for the gaseous medium using additional elements - pipes. The heat exchange surface, and thus the amount of inserted elements, is proportional to the required performance and stored energy and constitutes a significant part of the mass of the heat accumulator. Conducting heat between the storage material and the pipe wall requires a thermal gradient, which increases the temperature difference between the inlet and outlet temperatures, thereby reducing the efficiency of thermal energy storage. Additional elements for conducting the medium must withstand the maximum temperature in the accumulator, and possibly also the internal pressure of the medium. Metal materials with high heat resistance, applicable for these elements, have a high price, which significantly increases the cost of the accumulator in relation to the stored energy. Even with resistant metal materials, the mechanical properties decrease significantly with increasing temperatures, and often do not reach the temperature resistance of ordinary refractory materials. The use of metal materials in the area of high temperatures has its limits, which limit the working temperature and the storage capacity. Due to the price of the pipes, their cross-section must be minimized, which leads to a high flow rate and thus to a limited possibility of temperature stratification in the storage. The system using the heat from the accumulator must then accept a large range of outlet temperatures of the medium.

- 1 CZ 2023 - 173 A3

The disadvantage of the mentioned system with a thermosiphon system, as a heat transfer mechanism, is the dependence on the physical parameters of the medium, the interrelationship between pressure and temperature in the heat exchange circuit, while at high temperatures it is necessary to operate the heat exchange circuit at high pressures. The unidirectional flow of energy in a closed tube, from the lower end to the upper end, does not allow thermal stratification of energy storage. In addition, said system has the disadvantages of a closed gas circuit system, described above.

Similar tube solutions are known from Chinese patent application CN 108007246 A (thermal energy is stored in molten salt), Japanese patent application JP H102616 A (thermal energy is stored in a metal block), and American patent application US 2012111006 A1 (thermal energy is stored into loose material in the structural labyrinth of the storage space).

In the state of the art, there is therefore a need to provide a system and a corresponding method for storing and transferring heat with a higher thermal energy storage efficiency, which is characterized by the necessary thermal resistance, lower operating pressure, the possibility of thermal stratification of thermal energy storage and lower input costs in relation to the stored thermal energy .

The essence of the invention

The aim of the invention is to provide a system for storing and transferring heat, which uses non-metallic materials for the distribution of the heat exchange medium in the heat accumulator, and which ensures the recovery of heat losses passing through the heat-insulating shell of the storage. At the same time, this system enables a high degree of stratification of heat storage, and thus enables the re-use of stored thermal energy at permanently high temperatures, minimally different from the input temperature. The blower system (see below in more detail) allows precise regulation of output temperature and output.

The above-mentioned properties aim to improve the economic and technical parameters of thermal energy storage at high temperatures. An increase in the maximum working temperature and a continuous output of thermal energy at high temperatures will enable the use of heat storage technology in hitherto unused applications. High temperatures also usually increase the efficiency of technological processes and other energy transformations.

It is also an object of the invention to provide a method of storing and transferring heat that utilizes the system described here.

The stated goal is achieved by a system for storing and transferring heat, including

a. at least one heat source for generating heat energy;

b. high-temperature heat storage with bulk refractory material filling the high-temperature storage space for storing the generated thermal energy;

c. at least one heat consumption system for the use of stored heat energy; and

d. heat transfer mechanism for transferring heat from the heat source to the high-temperature heat storage and from the high-temperature heat storage to the heat consumption system, the heat transfer mechanism being a closed gas circuit connecting the heat source, the high-temperature heat storage and the heat consumption system, the high-temperature heat storage being partially sheathed with a load-bearing inner shell.

The essence of the mentioned system is that the bulk refractory material includes a fraction of particles with a sphericity in the range of 0.4 to 1 and with an average particle size in the range of 0.5 to 20 mm, while the volume ratio of the largest and smallest particles is a maximum of 5:1. The stated fraction of particles ensures

- 2 CZ 2023 - 173 A3 permeation of hot and cooled gas without the need to use gas pipes in bulk refractory material. The stated maximum ratio of 5:1 indicates maximum uniformity in particle size, thus ensuring the largest gap, and uniformity of particle temperature changes in the flowing gas, thereby minimizing the extent of the steep thermal gradient region. Requiring a uniform, excessively narrow aggregate fraction is technically more demanding than higher particle size tolerances. A higher particle size tolerance such as 5:1 will already have a major effect on the aggregate gap and heating uniformity, and at the same time have a minimal effect on the technical complexity of its preparation (and thus the price). At a ratio higher than 5:1, it would be a fraction containing particles of too different sizes, thereby reducing the mean size of the gaps between the particles.

The load-bearing inner shell is further covered with an outer heat-insulating shell so that there is a gas gap between the load-bearing inner shell and the outer heat-insulating shell to ensure recovery of heat losses from the high-temperature heat storage penetrating through the load-bearing inner shell. This gas gap, together with the connecting gas channel, connects the high-temperature heat storage with at least one technological space, which is further connected to at least one heat consumption system. The hot gas channel further connects the high-temperature heat storage with at least one heat source.

The load-bearing inner shell may contain high-temperature thermal insulation on the side adjacent to the high-temperature storage space for more effective prevention of heat transfer from the high-temperature heat storage to the load-bearing inner shell.

In one embodiment of the present invention, the heat source may be an inlet heat exchanger. A blower system can be arranged in the technological space for guiding the cooled gas from the high-temperature storage space through the gas gap, the connecting gas channel, the technological space and the first outlet gas channel to at least one input heat exchanger. At least one hot gas channel may be arranged to guide the hot gas from the inlet heat exchanger, leading from the inlet heat exchanger to the gas layer above the high-temperature storage space.

Alternatively or in addition to the embodiment above, the heat source can be at least one electrically heated body. In the technological space, a blower system can be arranged for guiding the cooled gas from the high-temperature storage space through the gas gap, the connecting gas channel and the technological space into the second connecting gas channel and the hot gas channel, and further in thermal contact with an electrically heated body for heating the gas into the gas layers above the high-temperature storage space. The electrically heated body can be arranged inside the supporting inner shell outside the high-temperature storage space, preferably in the hot gas channel.

In addition to the embodiments above, the heat transfer system may be an outlet heat exchanger. A blower system can be arranged in the technological space to guide the cooled gas from the output heat exchanger through the second inlet gas channel, the technological space, the connecting gas channel and the gas gap into the high-temperature storage space. At least one hot gas channel may be arranged for conducting hot gas from the high-temperature storage space, leading from the gas layer above the high-temperature storage space to at least one outlet heat exchanger.

The first inlet gas channel and the first outlet gas channel may be arranged coaxially with each other such that the first outlet gas channel surrounds the first inlet gas channel. Similarly, the second inlet gas channel and the second outlet gas channel may be arranged coaxially with each other such that the second inlet gas channel surrounds the second outlet gas channel. Similarly, the connecting gas channel and the hot gas channel can be arranged coaxially with each other such that the connecting gas channel surrounds the hot gas channel. The coaxial arrangement prevents the transfer of heat from the hot gas to the surroundings, and enables its recovery in the cooled gas.

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The gas gap can be connected via an air channel with a two-way valve, which is further connected to the environment via a safety inlet gas channel and a safety outlet gas channel. This ensures operational safety and the possibility of equalizing pressures.

The bulk refractory material can be any of the group consisting of basalt, andesite, dacite, artificial sintered aggregate, ceramic material, blast furnace slag, pressed graphite with glassy carbon on the surface, carbide and nitride.

In the first inlet gas channel, in the first outlet gas channel, in the second inlet gas channel, in the second outlet gas channel, in the inlet-outlet area of the cooled gas, in the area of the connection of the sink of the electrically heated body on the gas layer above the high-temperature accumulation area and in the area of the hot a temperature sensor can be arranged in the gas channel before entering the sump, and each temperature sensor is connected to the control unit.

A service space can be arranged under the high-temperature accumulation space for the location of the collection and transport system of the separated dust and/or for the location of the collection and transport system of the material to be overhauled.

At least one distribution valve for the entry of bulk refractory material at the operating temperatures of the high-temperature heat storage can open into the hot gas layer above the high-temperature storage space.

The mean particle size may be in the range from 0.5 mm to 20 mm, preferably from 0.5 mm to 10 mm, and the ratio of the mean particle size of the loose refractory material to the total height of the high-temperature storage space may be in the range of 1:1500 to 1 :6000.

The stated goal is further achieved by means of heat storage and transfer using the heat storage and transfer system described here. Said method includes the following heat storage steps:

a. generation of thermal energy in at least one heat source to produce hot gas;

b. transfer of hot gas from the heat source to the high-temperature heat storage using a heat transfer mechanism in the form of a closed gas circuit;

c. storing the generated thermal energy from the hot gas in a high-temperature heat storage with bulk refractory material contained in the high-temperature storage space to create cooled gas;

d. transfer of cooled gas from the high-temperature heat storage to the heat source using a heat transfer mechanism in the form of a closed gas circuit; and

e. optionally repeating steps a. to d.;

and then the following steps of stored heat consumption:

f. transfer of cooled gas from the heat consumption system to high-temperature heat storage using a heat transfer mechanism in the form of a closed gas circuit;

g. obtaining stored thermal energy from a high-temperature heat storage with bulk refractory material contained in a high-temperature storage space to generate hot gas;

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h. transfer of hot gas from high-temperature heat storage to the heat consumption system using a heat transfer mechanism in the form of a closed gas circuit;

i. consumption of stored heat energy from hot gas in at least one heat consumption system.

The essence of the mentioned method is that the bulk refractory material includes a fraction of particles with a sphericity in the range of 0.4 to 1 and with an average particle size in the range of 0.5 to 20 mm, while the volume ratio of the largest and smallest particles is a maximum of 5:1 . In steps d. and f., heat losses escaping from the high-temperature heat storage, caused by heat penetration through the supporting inner shell surrounding the high-temperature heat storage, are recovered by passing the cooled gas through the gas gap arranged between the supporting inner shell and the outer heat-insulating shell surrounding the supporting inner shell .

The term "loose" material means "loosely loose" material.

The essence of the invention consists in storing thermal energy directly in bulk refractory material, without the help of a closed pipe system inside the storage space. The recovery of heat losses ensures a substantial reduction in the dependence of the magnitude of heat losses to the external environment on the level of the internal temperature. The economically achievable value of the maximum internal temperature will be significantly increased in this way.

To limit heat leakage from the high-temperature storage space, the load-bearing inner shell is provided with high-temperature thermal insulation on the inside, which can be made as a layered insulation that uses various heat-resistant and high-temperature insulation materials. The optimal parameters of the high-temperature thermal insulation and the inner shell are dependent on the optimization calculations after entering the economic, operational and physical parameters. The size and shape of the heat storage, as well as the required time and power parameters of heat storage and extraction, have a great influence.

The optimization calculation takes into account the difference in the intensity of the heat flow (Ti) passing through the high-temperature thermal insulation and in the intensity of the heat flow (Te) passing through the outer thermal insulation shell, in relation to the area thermal capacity (Cpi) of the shell. This gives the rate (Rpl; in units of K.s) of the heating of the shell of the high-temperature storage space when the flow of cooled gas in the gas gap stops (stopping the withdrawal of thermal energy from the output heat exchanger).

Cpi

Rpl = —-—

[You — You)

The basic design parameter is the time (T; in units of s) during which no thermal energy is to be taken from the storage (or the parameter of minimum thermal energy withdrawal for a certain period of time), and the temperature difference between the cooled gas (t_chl) that returns to storage after removing thermal energy in the output heat exchanger, and the highest possible temperature in the gas gap and in the technological space (t_max).

Cpi

T = . (t_max —t_chV)

The calculations result in the smallest heat losses through the outer heat-insulating jacket with uniform energy consumption from the heat storage (during which the temperature in the gas gap will be kept at a minimum level by the flow of cooled gas from the outlet heat exchanger). The temperature in the gas gap (and thus the total heat loss) will start after the interruption of heat extraction from the storage

-5 CZ 2023 - 173 A3 slowly increase with the temperature of the supporting inner shell. Interruption of heat extraction in the order of hours, high unevenness of energy supply, and the state of acquisition of the storage (average temperature) therefore do not greatly affect the total heat loss to the external environment. To minimize heat loss to the external environment, the main importance is the maximization of the thermal resistance of the external heat-insulating jacket, and the regular consumption of thermal energy. The longer the time periods without energy consumption the storage must maintain, the higher is the necessary area thermal capacity of the inner supporting shell, or the thermal resistance of the outer heat-insulating shell and equipment of the technological space.

The main advantages of the system described here:

• It solves the temporal inconsistency of the supply and demand of heat and electricity, with lower requirements for expensive materials, with more attainable lower heat losses, and thus with higher efficiency.

• The high temperature of the stored energy and the continuous supply of energy through a high-temperature gas medium enable the technological use of heat storage where it was not possible until now.

• Thanks to the high temperature, the conversion (according to demand) to another form of energy, e.g. electricity using a gas turbine or other heat engine or thermoelectric generator, is effective.

• High temperatures, which are technologically easier to achieve, enable high energy storage density to be achieved at lower costs. For silicate refractory materials (e.g. basalt (basalt) with a gap of 0.46 at a temperature difference of 800 K), the storage has a thermal capacity of 1.27 GJ/m ³ , which corresponds to 120 to 180 kWh of electrical energy at 35 to 50% heat transfer efficiency energy in a heat engine (the highest efficiency is possible with a combination of gas and steam turbines, common in steam-gas power plants).

• The internal flow system ensures the recovery of heat energy losses passing through the heat-resistant insulation. The outer casing of the storage has low heat losses to the external environment, derived from the temperature of the cooled heat storage.

• No toxic or chemically reactive liquid substances that endanger the environment or increase operational risks are used.

• Accumulation material and storage casing are currently mass-produced materials for road and building construction.

From the point of view of availability of large volumes and price, common bulk natural and artificial materials are suitable. Their appropriate grain size, size and ratio of voids to solid material, and surface density are determined according to optimization calculations after entering the economic and physical parameters of locally available materials. The size and shape of the heat storage also have a big influence. For optimal storage function, the ideal shape is a cylinder, or a body with vertical or nearly vertical walls with a plan section in the shape of a square, circle, ellipse or regular polyhedron (5 or more walls). In general, it is desirable to achieve the smallest possible surface-to-volume ratio, which leads to higher efficiency for larger storage volumes. The possible performance of stored and recovered energy is directly dependent on the floor plan area of the storage, and indirectly on the height of the storage.

The storage parameters will be largely determined by the physical parameters of the solid particles (bulk refractory material) filling the high-temperature accumulation space of the storage. Of the natural materials, microcrystalline pouring rocks with a minimum of alkali (Na2O, K2O) with high strength and heat resistance are suitable. These are mainly basalt, andesite and dacite. For their assessment of the suitability of a particular material, tests verifying its resistance to thermal cycles will be necessary. For smaller storage ranges, manufactured artificial aggregates will be particularly suitable

- 6 CZ 2023 - 173 A3 by sintering at high temperatures, similar to ceramics. Blast furnace slag is also usable.

In order to ensure favorable storage parameters, loose solid particles must have, in addition to their own weight and heat capacity, a significant proportion of gaps that allow gas to circulate around the solid particles. This condition is best achieved with a narrow range of solid particles fraction, without fine and dust fractions, and with high sphericity (close to spherical shape). The roundness of the edges of the particles does not have a clear positive or negative effect on the physical parameters of the repository. Sharp or only slightly rounded edges increase the specific surface area and gap, and thus improve the parameters, but on the other hand, they lengthen and curve the gas path between the particles, and thus have the opposite effect. From the point of view of mechanical resistance, and thus also the lifetime of the particles, a higher roundness of the edges will be suitable. The surface of the particles with a microcrystalline structure has only a small roughness, which will mostly affect the pressure loss only negligibly in slow laminar flow. Favorable parameters for heat sharing in storage are provided by a large heat exchange surface (surface of solid particles related to volume or weight - specific surface). This area is most dependent on the mean particle size. A small solid particle size is beneficial for heat sharing, but decreasing particle size causes an increase in pressure drop.

From the mathematical-physical analyzes carried out, it appears appropriate to maintain the ratio of the total height of the storage storage space to the average particle size of the bulk refractory material in the range of 1:1500 to 1:6000. In common technical practice, this will mean average particle sizes in the range from 0.5 mm to 20 mm, preferably from 0.5 mm to 10 mm, with the maximum difference in particle size in a specific application up to a ratio of 5:1 (the largest to smallest particle size). The basic parameter is the required performance of thermal energy storage and extraction based on 1 m ² of floor plan area of the storage storage area. This parameter can be significantly different for storage, and for recovery of thermal energy. In addition to the performance of the blowers, the possible maximum power of thermal energy storage/absorption is mainly limited by the height of the area of the steep thermal gradient, which is created when the gas flows through the storage space. This area can be defined by the fact that 90% of the gas temperature change takes place in it when the gas flows through the storage space. The height of the area of the steep thermal gradient is a basic parameter for the design of the storage storage space. The calculation of this height is a task for the mathematical-physical analysis of gas flow through a porous medium - a layer of material particles. If the other parameters are maintained, the size of this height increases depending on the gas flow rate, and thus depending on the power.

An example of this dependence is shown in Fig. 2 - increasing the height of the steep thermal gradient region depending on the flow rate. The maximum extent of the steep thermal gradient area to ensure the heat storage function is half the height of the storage space. In general, a more efficient storage will be at a power/flow rate where the ratio of the height of the steep thermal gradient region to the height of the storage space is higher (eg 1:4, 1:5, 1:6, 1:7 or 1:8).

If there is a need to increase the performance parameter per m ² of the floor plan area of the repository, it is necessary to reduce the average particle size of the bulk refractory material in order to reduce the height of the area of the steep thermal gradient. An example of this dependence is shown in Fig. 3 - the reduction of the height of the area of steep thermal gradient depending on the reduction of the mean particle size of the bulk refractory material.

Two-way driving of gas through the storage facility will be ensured by a system of blowers. It is advisable that the performance of the blower system, compensating the pressure loss, be in an economic ratio to the projected heat output of the flowing gas medium in the heat storage. In the event that the input thermal energy is generated at least in part from electrical energy, it may be advantageous to use significantly higher flow rates (higher blower system performance) in thermal energy storage than in the reverse output flow, since virtually all energy used for mechanical work in heat storage is ultimately transformed into stored thermal energy. From the point of view of the requirement for the performance of the blowers, for technical practice, parameters of extra-layer flow velocity in the range of 0.01 - 1 m/s (permeation of 0.01 - 1 m ³ of gas through an area of 1 m ² /s) and pressure loss in the order of 10 ² are suitable up to 10 ⁴ Pa/m of the height of the storage storage area.

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For the technical feasibility of the storage, a high degree of reliability of computational mathematical-physical modeling of the accumulation space of the heat storage is required. Fundamental parameters specifying a specific material in a mathematical-physical model, such as pressure loss, heat transfer coefficient and heat capacity, can be verified in the laboratory on a small sample of a specific material.

The cost of the energy storage material, including the cost of processing and transportation, will become more important as the storage size grows. For smaller storage in the order of tens of m ³ in volume, loose ceramic materials or artificially sintered aggregates with a low value of thermal conductivity and less emphasis on volumetric weight will be optimal (eg light granulate from expanded clays brand Liapor 4-8/600). For large storage facilities, the thermal conductivity parameter will lose its significance and it will be possible to use cheaper, thermally additional natural materials with high efficiency. It is also possible to optimize the overall properties of the storage storage material by mixing solid particles of similar size but with different material parameters, or by depositing materially different particles in layers to promote heat stratification in the storage.

Virtually all particles, even those made of very resistant materials, will suffer surface disruption and separation of dust particles due to thermal cycles and resulting volume changes. These dust particles accumulate in channels between particles of normal size, and are carried away by the gas, especially in the downward flow. In normal storage operation, the required peak input heat output will be higher than the output, and thus the downward flow rate through the high-temperature storage space will be higher than upward. Therefore, after exiting the lower part of the high-temperature storage space, the gas will pass through a dust separator (ideally a cyclone separator complete with a filter) to prevent pipe lines and heat exchangers from becoming clogged with dust. The gas flow during heat recovery takes place from the bottom up and therefore carries away only exceptionally fine dust particles, without the risk of settling in the gas channel system. This flow can additionally recover the filters of the separator (preferably equipped with a vibrator).

Particle erosion, especially in durable sintered ceramic materials, is slow but permanently reduces the functional parameters of the repository. As a result of particle erosion, there is clogging and reduction of the cross section of the channels between the particles. The result is an increase in pressure loss, and due to the decrease in thermal conductivity on the surface of the particles, also a decrease in the heat transfer coefficient. When designing the storage, it is therefore necessary to ensure the possible one-time replacement or gradual replacement of bulk refractory material in the high-temperature storage space. In the case of large storage facilities, gradual overhaul and replenishment will be more practical without the need to cool down the entire storage facility, thereby significantly affecting the operation.

Part of the example of the realization of this invention is the solution of gradual replacement of bulk refractory material (filling of the high-temperature storage space). The goal of the solution is to ensure standard, sustainable energy storage conditions. Erosion takes place by separating the surface parts in sizes corresponding to the fineness of the material structure. With natural materials, it occurs faster, separating larger dust particles and less evenly than with artificial ceramic materials (finer, more uniform and more sintered structure). In general, it can be assumed that it will be possible to reprocess bulk refractory material by beating (e.g. in a drum mixer) and sieving (e.g. vibrating sieve under a slight slope). To reduce dust and noise and improve the quality of the process, simultaneous washing with water is suitable. Before leaving the sieve, the material is freed from water and dust on the surface by an air stream. During washing, it is further dried by passing through a slowly rotating cylinder, or by forced passage of air with reduced humidity through a reservoir. Unusable material with insufficient strength and size is separated in this way, and still suitable material is freed from disturbed surface, dust and unwanted smaller particles. The result is then a reusable, desired narrow fraction of bulk refractory material. The rest after overhaul of the so-called "sub-mesh" can be used in another, smaller or more efficient type of storage where smaller particles are desired, or used in another way. Residual dust and battered material can be further sorted and processed in the production of ceramic materials, or it can be used for

- 8 CZ 2023 - 173 A3 production of new ceramic refractory sintered particles. Energy storage technology will thus have minimal environmental impact.

In principle, the storage can also be operated at temperatures higher than the normal heat-resistant silicate materials can withstand. However, it will require the construction of all hot parts of the storage from high-temperature materials with higher resistance, and with an inert gas as a medium. A sufficiently solid form of carbon or its compounds in the form of carbides is suitable as storage material for maximum temperatures. As a heat-insulating material for temperatures up to 3000 °C, wool or foam made of carbon fibers and graphite can be used. Heating the storage to temperatures above 1200 °C can be effectively solved only with electricity, using graphite resistance elements, carbon resistance fibers, or a non-contact induction system.

Clarification of drawings

fig. 1 schematically shows a high-temperature heat storage (solid line with arrows shows hot gas, dashed line with arrows shows cooled gas, dashed line without arrows shows electrical lines).

fig. 2 shows the increase in the height of the region of the steep thermal gradient as a function of the increase in the flow rate (the upper part of the columns shows the highest temperature and the lower part of the columns the lowest temperature).

fig. 3 shows the decrease in the height of the steep thermal gradient region as a function of the decrease in the mean particle size of the bulk refractory material (the upper part of the bars shows the highest temperature and the lower part of the bars the lowest temperature).

fig. 4 are functional diagrams of heat exchange circuits (solid line with arrows represents hot gas, dashed line with arrows represents cooled gas).

fig. 5 schematically shows the distribution valve.

Examples of implementation of the invention

Construction of high-temperature heat storage

An arrangement of high-temperature heat storage, where thermal energy is bound through a solid bulk refractory material, is shown in Fig. 1. In this embodiment, the high-temperature storage includes a thermally insulated space within an outer thermally insulating shell 5. The majority of the thermally insulated space within the outerly thermally insulating shell 5 shell 5 is filled by the load-bearing inner shell 3 with high-temperature thermal insulation 2 and the high-temperature storage space 14, which is surrounded from the top and sides by the load-bearing inner shell 3 with high-temperature thermal insulation 2 and from the bottom side surrounded by the grate with gas channels 14.7. A gas gap 4.1 is formed between the outer heat-insulating shell 5 and the supporting inner shell 3, and further preferably a connecting gas channel 4.3, or air channel 13.3 (see more detailed description below).

The lower part of the thermally insulated space inside the outer heat-insulating jacket 5 fills the service space 22. In the service space 22, under the grate with gas channels 14.7, there is at least one hopper 21.1, at least one dust separator 20.1, and collection and transport can also be installed in the service space a system 20 of separated dust and a collection and transport system 21 of material for overhaul. Bulk refractory material in hopper 21.1 and volume

- 9 CZ 2023 - 173 A3 of the dust separator 20.1 is preferably isolated from the rest of the service space 22 by thermal insulation 5.2 of the service space. The base structure of the high-temperature heat storage preferably consists of a base plate 3.1 lying on a load-bearing thermal insulation 5.1 (e.g. foam glass gravel) connected to the outer heat-insulating jacket 5.

At least one technological space 4.2 is located inside the outer heat-insulating shell 5 in any arrangement relative to the supporting inner shell 3, or in a separate space, which is preferably located at the height of the service area and/or next to the supporting inner shell 3. Separately the separate technological space 4.2 is preferably connected to the other parts of the thermally insulated space inside the outer heat-insulating shell 5 by the coaxial heat input-output 7.3, when the gas channel with a higher temperature is inside the gas channel with a lower temperature.

The mentioned gas channel with a higher temperature in the coaxial heat input-output 7.3 connects to the hot gas channel 7 running through the high-temperature thermal insulation 2 and opening into the upper part of the high-temperature accumulation space 14 (into the gas layer 14.6). The mentioned gas channel with a lower temperature in the coaxial heat input-output 7.3 is connected to the connecting gas channel 4.3 running between the outer heat-insulating shell 5 and the supporting inner shell 3, and opening into the gas gap 4.1 at the point of the input-output 6 of the cooled gas. The inlet-outlet 6 of the cooled gas is always located above the high-temperature storage space 14, near the highest point of the gas gap 4.1. With a large floor plan area of the storage, it may be advantageous to use multiple inlets-outlets 6 of the cooled gas. The hot gas channel 7 and the connecting gas channel 4.3 can therefore advantageously be arranged coaxially to the heat input-output 7.3, in such a way that the connecting gas channel 4.3 surrounds the hot gas channel 7. With a large floor plan of the storage, it can be advantageous to use several connecting gas channels channels 4.3 and hot gas channels 7.

Furthermore, the technological space 4.2 can be connected to at least one output heat exchanger 12. The output heat exchanger 12 is preferably connected by a coaxial heat output 7.2, when the gas channel with a higher temperature is inside the gas channel with a lower temperature. Furthermore, the technological space 4.2 can be connected to at least one input heat exchanger 11. The input heat exchanger 11 is preferably connected by a coaxial heat input-output 7.3.

The gas gap 4.1 is further connected on the lower side to the service space 22 and to the air channel 13.3. This air channel 13.3 is connected to the heat-insulating two-way valve 13, which is further connected to the safety inlet gas channel 13.2. The two-way valve 13 is also connected to the upper part of the connecting gas channel 4.3 and to the emergency gas outlet 13.1. The two-way valve 13 can be connected via the magnetic clutch 15.4 to the servo drive 15.3.

The load-bearing inner shell 3 defines the high-temperature accumulation space 14 around the internal volume of the heat storage and is made of sufficiently tight and load-bearing material to maintain the shape of the storage filled with loose material, e.g. monolithic concrete, tightly connected concrete prefabricated parts, steel sheet, ceramic parts, dense enough thermally - durable fibrous composite boards, and combinations of these materials. The load-bearing inner shell 3 is also a load-bearing structure for heat storage and is created as a secondary heat-accumulation layer. On the inner side of the supporting inner shell 3, adjacent to the high-temperature storage space 14, a high-temperature thermal insulation 2 is arranged defining the high-temperature storage space 14, in which the bulk refractory material 1 is arranged.

The floor plan area and height of the high-temperature storage space 14 is derived both from the design capacity and a suitable ratio ensuring the minimization of the surface of the average hot storage volume 14.4, and from the appropriate height of the entire high-temperature storage space 14. Better parameters of the high-temperature storage space 14 are ensured by a space with a greater height. This is due to the need to meet the condition of at least double, optimally 4- to 8-fold, the height of the area 14.3 steep thermal gradient, defined as an area in which

- 10 CZ 2023 - 173 A3 the flowing gas changes 90% of the temperature difference between the mean temperature of the cooled storage space 14.5 and the mean temperature of the hot storage space 14.4. The height of the steep thermal gradient region 14.3 increases with gas flow rate (Fig. 2), and decreases at the same rate with decreasing bulk refractory particle size (Fig. 3). The height of the steep thermal gradient region 14.3 is calculated using Ergun's pore zone flow equation and the heat sharing equations in the mathematical-physical model. The proposed average particle size of the bulk refractory material 1 filling the high-temperature storage space 14 corresponds to 1/1500 to 1/6000 of its height, with a maximum difference in particle size in a specific application of up to a ratio of 5:1.

Of the natural materials, loose refractory material 1 can be considered especially microcrystalline pouring rocks, with a minimum of alkaline admixtures, such as basalt, andesite, dacite, etc. Of the artificial materials, ceramic sintered aggregates with a high volumetric weight and spherical particle shape are particularly suitable. For special applications with temperatures above 1200 °C, a sufficiently solid form of carbon (e.g. graphite pressed into pellets with glassy carbon on the surface) or its compounds in the form of carbides and nitrides can be used. Advantageous overall properties can also be achieved by mixing or layering particles of a similar fraction, but with different material properties (e.g. in terms of bulk density and thermal conductivity).

High-temperature thermal insulation 2 can be made as a layered insulation that uses heat-resistant and high-temperature insulation materials. In addition to price, refractory materials differ significantly in terms of heat resistance and thermal insulation properties. The internal local temperature in the insulation decreases from the inner to the outer face of the insulation. Insulation with excellent parameters at high temperatures are up to several times more expensive than thermal insulation effective only at lower temperatures. Therefore, it is advisable to divide the overall thermal insulation into layers operating in a certain range of temperatures. The materials of the individual layers can then be designed with regard to the calculated maximum local temperature. In this way, the resulting price and the thickness of the thermal insulation can be optimized. The highest efficiency at high temperatures is characterized by microporous ceramic insulations (e.g. opacified fumed silica mixtures using silicon carbide or titanium dioxide, e.g. FREEFLOW brand from PrOmAT). However, a cheaper material with worse properties (e.g. expanded perlite and/or expanded vermiculite) may be more cost effective.

Thermal insulations do not have high mechanical resistance. For practical use in heat storage, it is necessary to bind them inside a material resistant to pressure and abrasion. Ideal for temperatures of 500 to 1200 °C can be a layer assembled using ground insulating ceramic bricks (e.g. POROTHERM brand with cavities filled on the outside with expanded perlite and on the inside with microporous insulation). For applications on a smaller scale, mechanically weak high-temperature insulation can be protected with a tight surface layer, e.g. from refractory sheet (e.g. refractory, alloyed, noble, austenitic steel class 1.4828 according to AISI 309, ČSN 17251 standards). Better thermal insulation properties can also be achieved by vacuuming the layer.

For the layers at lower operating temperatures on the outside of the high-temperature insulation (in local temperatures up to 500 to 600 °C), significantly cheaper mineral and ceramic fiber materials (e.g. stone wool board of the ORSTECH 100 brand from ISOVER) are already effective.

The outer heat-insulating shell 5 can include mutually sealed assembled elements with a sandwich construction (sheath - insulating core - shell), anchored to the supporting inner shell 3 with a distance forming an air gap 4.1, e.g. industrially produced sandwich panels of the sheet metal - mineral wool - sheet metal type .

Inside the upper part of the high-temperature thermal insulation 2, at least one sump 8.1 for the electrically heated body 8.2 is preferably arranged, which is connected on the lower side to the hot gas channel 7 and on the upper side to the gas layer 14.6 above the high-temperature accumulation space 14. The sump 8.1 opens onto the outer face of the outer heat-insulating jacket 5, and its inner part is filled from the mouth to the inner face of the high-temperature heat insulation 2 with heat-insulating

- 11 CZ 2023 - 173 A3 material. At least one electrically heated body 8.2 (e.g. resistor, induction heating) is arranged in the sump 8.1, which is connected to the electric voltage source 8.

Inside the technological space 4.2 there is a system of 10 blowers, which includes a combination of at least two blowers enabling flow in one input heat exchange circuit 9.1 or 9.3 of heat and in one output heat exchange circuit 9.2 of heat. Advantageously, the system of 10 blowers also includes other valves and blowers, enabling the simultaneous function and connection of several heat exchange circuits. Blower drives 15.5 and any valve servo drives 15.3 are preferably located on the outside of the outer heat-insulating jacket 5.

Heat exchange circuits

The blower system 10 ensures gas flow in at least one input and one output heat exchange circuit (Fig. 4), whereby the input heat exchange circuit can be the input heat exchange circuit 9.1 heat or the input heat exchange circuit 9.3 heat with electric heating. Advantageously, the blower system 10 ensures flow in the output heat exchange circuit 9.2 or in the output heat exchange circuit 9.4 with output temperature control, and/or in combination 9.5 of heat exchange circuits with a predominance of inputs and in combination 9.6 of heat exchange circuits with a predominance of outputs. Advantageously, the blower system 10 allows in these combined heat exchange circuits (9.5 and 9.6) to reduce the output temperature in the output heat exchanger 12. When all heat exchange circuits are operating, the electrically heated body 8.2 can supply heat. The diagram of the heat exchange circuits is shown in Fig. 4a to 4f.

The heat input heat exchange circuit 9.1 (Fig. 4a) represents the connection of the blower system 10, successively on the suction side, with the technological space 4.2, with the connecting gas channel 4.3, with the inlet-outlet 6 of the cooled gas, with the gas gap 4.1, with the dust separator 20.1, with a grate with gas channels 14.7 below the high-temperature accumulation space 14. On the outlet side, the blower system 10 is successively connected to the first outlet channel 10.1, to the inlet heat exchanger 11, to the first inlet channel 11.1, to the hot gas channel 7, and to the hot gas layer 14.6 above the high-temperature storage space 14, and between the end of the hot gas channel 7 and the hot gas layer 14.6, a sump 8.1 with an electrically heated body 8.2 is preferably located.

The heat output heat exchange circuit 9.2 (Fig. 4b) represents the connection of the blower system 10, successively on the suction side, with the second input gas channel 10.2, with the output heat exchanger 12, with the second output channel 12.1, with the hot gas channel 7 and with the hot gas layer 14.6 above the high-temperature storage space 14, and between the end of the hot gas channel 7 and the hot gas layer 14.6, a sump 8.1 with an electrically heated body 8.2 is preferably located. On the outlet side, the system of 10 blowers is successively connected to the technological space 4.2, to the connecting gas channel 4.3, to the inlet-outlet 6 of the cooled gas, to the gas gap 4.1, to the dust separator 20.1, and to the grate with gas channels 14.7 under the high-temperature accumulation space 14.

The input heat exchange circuit 9.3 with electric heating (Fig. 4c) represents the connection of the system of 10 blowers, successively on the suction side, with the technological space 4.2, with the connecting gas channel 4.3, with the inlet-outlet 6 of the cooled gas, with the gas gap 4.1, with the separator 20.1 dust, with a grate with gas channels 14.7 below the high-temperature accumulation space 14. On the output side, the blower system 10 is successively connected to the second connecting gas channel 10.3, to the hot gas channel 7, to the sump 8.1 with the electrically heated body 8.2 and to the hot gas layer 14.6 above high-temperature storage space 14.

The other heat exchange circuits (9.4, 9.5, 9.6) use only the physical connection of the input and output heat exchange circuits (9.1, 9.2, 9.3) described above.

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Additional functions and management

The distribution valve 16 serves as the input for refilling the loose refractory material, its location is always above the hot gas layer 14.6, while the use of several distribution valves 16 may be advantageous in the case of a large storage area. On the lower part 17.6 of the inner body of the distribution valve, there is a hot gas a vibrating plate 18 is attached to layer 14.6. Part of the distribution valve are electrically controlled elements in the form of a valve servo drive 15.3, a vibrator 15.8 and an electromagnetic clutch 17.7 of the distribution valve, connected behind the thermal fuse 15.6. The internal structure and function of the distribution valve 16 is shown in Fig. 5 and is part of a separate description, see below. The distribution valve 16 is connected to the bulk refractory material transport system 19 via the replenishment channel 19.3. In the case of using multiple distribution valves 16, the replenishment channel 19.3 is led from the distributor 19.1, and this is then connected to the system 19 for transporting bulk refractory material.

An exemplary high-temperature heat storage system also includes a measurement and regulation system containing a control unit 15.1, which is connected to the power source 8, to the drives 15.5 and the servo drives of the blower system 10, via the thermal fuse 15.6 to the electromagnetic clutch 15.4 and the valve servo drive 15.3, and to the electrically controlled elements of the distribution valve 16 via the thermal fuse 15.6 to the servo drive 15.3 of the valve, the vibrator 15.8, and to the electromagnetic clutch 17.7 of the distribution valve. When using more than one distribution valve 16, the control unit is preferably also connected to the servo drive 19.2 of the distributor, the system 19 for transporting loose refractory material, and monitors the pressure loss of the dust separator 20.1 and controls its regeneration, controls the collection and transport system 20 of the separated dust and controls collection and transport system of 21 materials for overhaul.

Furthermore, the control unit 15.1 is connected to the temperature sensors 15.2, which are arranged both in the first outlet gas channel 10.1 and the first inlet gas channel 11.1, and to the temperature sensors 15.2, which are arranged in the second inlet gas channel 10.2 and the second outlet gas channel 12.1, and to the temperature sensors 15.2, which are arranged in the inlet-outlet space 6 of the cooled gas. Advantageously, the control unit is connected to the temperature sensors 15.2 at the point of connection of the well 8.1 to the gas layer 14.6, and at the point of connection of the well 8.1 to the hot gas channel 7.

The control unit 15.1 is further connected to the accelerometer 15.9 in the distribution valve 16 and is preferably also connected to the flow and differential pressure meter 15.7 in the first outlet gas channel 10.1.

Operation of high-temperature heat storage

The function of high-temperature heat storage is implemented using heat exchange circuits with gas as the working medium, schematically shown in Fig. 4. Preferably, an inert gas is used, but for temperatures up to 1000 °C, air can also be used with a suitable choice of materials. The heat exchange circuits are activated by a system of 10 blowers. The working temperature of the blower system 10 is given by the temperature in the technological space 4.2, which is derived from the temperature of the gas in the second inlet gas channel 10.2, and the temperature in the gas gap 4.1. A significant increase in the working temperature of the blower system 10 can enable the placement of the drives 15.5, the servo drives of the blower system 10, as well as the measurement and regulation control system under normal temperature conditions outside the outer heat-insulating jacket 5.

The heat storage works in at least two heat exchange circuits, one of which transfers heat to the storage, and the other transfers heat to the exiting gas. The output heat exchange circuit 9.2 of heat ensures the transfer of heat from the storage to the output heat exchanger 12. The transfer of heat to the storage can take place via two heat exchange circuits, the input heat exchange circuit 9.1 of heat, or the input heat exchange circuit 9.3 of heat with electric heating. An advantage may be the possibility of reducing the outlet temperature of the gas stream to the outlet thermal temperature

- 13 CZ 2023 - 173 A3 of the exchanger 12, realizable by means of the heat exchange circuit 9.4 of heat with output temperature control. Another advantage can be the possibility of the storage to ensure different simultaneous power combinations of heat input and output from the storage, this is how the combination of 9.5 heat exchange circuits can work:

• The heat input heat exchange circuit 9.1, transferring the heat of the gas flow in at least one input heat exchanger 11, is activated when heat is supplied in the input heat exchanger 11, or when electricity is simultaneously supplied to the electrically heated body 8.2. The blower system 10 sucks gas from the technological space 4.2 and pushes it through the first outlet gas channel 10.1 into the inlet heat exchanger 11. It is advantageous if the first outlet gas channel 10.1 and the first inlet gas channel 11.1 from the inlet heat exchanger 11 are guided by a coaxial pipeline in the form input 7.1 heat. The pressure drop created by the blower system 10 enables the gas to flow through the high-temperature heat storage and at the same time in the inlet heat exchanger 11. The hot gas from the first inlet gas channel 11.1 flows into the hot gas channel 7, and can then flow through the sump 8.1 around the electrically heated body 8.2, where of gas, with possible active supply of electricity, further increases the temperature. It then enters the hot gas layer 14.6 above the high-temperature storage space 14 into the bulk refractory material 1 on the upper side of the hot storage volume 14.4. After passing through the hot storage volume 14.4, it enters the region 14.3 of a steep thermal gradient, where it transfers heat to the loose refractory material 1. The gas then flows into the cooled storage volume 14.5, and after passing through the cooled storage volume 14.5, it flows into the grate with gas channels 14.7 on its lower side. The gas further flows through the dust separator 20.1 into the gas gap 4.1, arranged around the supporting inner shell 3 of the high-temperature storage space 14, while the gas gap 4.1 is connected by the inlet-outlet 6 of the cooled gas and the connecting channel 4.3 to the technological space 4.2, thereby closing the gas flow circuit .

• The output heat exchange circuit 9.2 of heat, transferring heat to the gas stream in at least one output heat exchanger 12, is activated when there is a demand for heat. The blower system 10 sucks gas from the second inlet gas channel 10.2 and pushes the gas into the technological space 4.2. It is advantageous when the second inlet gas channel 12.1 and the second outlet gas channel 10.2 from the outlet heat exchanger 12 are guided by a coaxial pipeline, in the form of a heat output 7.2. The pressure drop created by the system of 10 blowers will allow the gas to flow through the high-temperature heat storage and at the same time in the outlet heat exchanger 12. The cooled gas flows into the technological space 4.2, the connecting channel 4.3, then through the inlet-outlet 6 of the cooled gas into the gas gap 4.1, which surrounds the supporting inner shell 3. The cooled gas is preheated by passing around the supporting inner casing 3. It then passes (as a backflow without necessary effect) through the dust separator 20.1, the grate with gas channels 14.7, and enters the loose refractory material 1 on the lower side of the cooled storage volume 14.5. After passing through the cooled storage volume 14.5, in the region 14.3 of the steep thermal gradient, it receives heat from the bulk refractory material 1, and further passes through the hot storage volume 14.4 into the hot gas layer 14.6. It can then pass through the sump 8.1, past the electrically heated body 82. It then enters the hot gas channel 7 and the outlet gas channel 12.1. After passing through the outlet heat exchanger 12, the cooled gas returns through the second inlet gas channel 10.2, thereby closing the circuit.

• The input heat exchange circuit 9.3 of heat from electrical energy, transferring the heat of the gas stream in at least one electrically heated body 8.2, is activated when electrical energy is supplied to the electrically heated body 8.2. The blower system 10 sucks gas from the technological space 4.2 and pushes it through the second connecting gas channel 10.3 into the hot gas channel 7, then flows through the sump 8.1 around the electrically heated body 82, and enters the hot gas layer 14.6 above the high-temperature accumulation space 14 into the bulk refractory material 1 on the upper side of the hot storage volume 14.4. After passing through the hot storage volume 14.4, it enters the region 14.3 of steep thermal

- 14 CZ 2023 - 173 A3 of the gradient, where it transfers heat to the bulk refractory material 1. The gas further flows into the cooled storage volume 14.5 and after passing through the cooled storage volume 14.5 on its lower side flows into the grate with gas channels 14.7. The gas further flows through the dust separator 20.1 into the gas gap 4.1, arranged around the supporting inner shell 3 of the high-temperature storage space 14, while the gas gap 4.1 is connected by the inlet-outlet 6 of the cooled gas and the connecting channel 4.3 to the technological space 4.2, thereby closing the gas flow circuit .

Advantageously, the storage also works in the following heat exchange circuits:

• Output heat exchange circuit 9.4 heat with output temperature control, transferring heat to the gas stream in the same way as in output heat exchange circuit 9.2 heat, but with the addition of the functionality of the 10 blower system. Advantageously, the blower system 10 will also simultaneously provide continuous regulation of the gas flow from the technological space 4.2 through the second connecting gas channel 10.3 to the hot gas channel 7.

• Combination of 9.5 heat exchange circuits, transferring heat to the gas stream in the same way as in the input heat exchange circuit 9.1 of heat, and at the same time in the same way as in the output heat exchange circuit 9.2 of heat, but with the addition of the functionality of the 10 blower system. The blower system 10 will preferably additionally ensure continuous regulation of the gas flow into the first outlet channel 10.1, continuous regulation of the gas flow from the second input channel 10.2, and continuous regulation of the gas flow from the technological space 4.2, through the second connecting gas channel 10.3 to the hot gas channel 7.

The cooled gas, passing around the supporting inner shell 3 of the high-temperature accumulation space 14 before entering the input heat exchanger 11, is preheated by thermal energy passing through the high-temperature thermal insulation 2 into the supporting inner shell 3. The mass of the supporting inner shell 3 accumulates this thermal energy for a limited time, while this time, in the order of units, a maximum of tens of hours (given by the temperature increase limit and the ratio of the thermal capacity of the supporting inner shell and the heat flow through the high-temperature thermal insulation), is the maximum break in the operation of the output heat exchanger 12. This time is given by the ratio of the thermal capacity of the supporting inner shell 3 and the heat flow through the high-temperature thermal insulation 2 and the limit temperature in the gas gap 4.1 and the technological space 4.2.

The inner side of the outer heat-insulating shell 5, the gas gap 4.1, nor the technological space 4.2 is not exposed to extreme temperatures when the measurement and regulation system is functioning properly, only to temperatures increased compared to the temperature of the returning cooled gas from the outlet heat exchanger 12. The degree of possible temperature increase in the technological space 4.2 is determined by the thermal resistance of the blower structure and the external heat-insulating jacket 5. In the event of a malfunction or failure of the measurement and regulation system, the power supply to the magnetic clutch 15.4 and the valve servo drive 15.3 is automatically disconnected by the thermal fuse 15.6. The two-way valve 13 is designed so that it opens or remains open without external force. The two-way valve 13 simultaneously opens the connection between the safety output gas channel 13.1 and the connecting gas channel 4.3 and between the air channel 13.3 and the safety input gas channel 13.2. The hot gas in the gas gap 4.1 and the service space 22 is then self-gravitated. The effectiveness of the ventilation can be enhanced by the "chimney effect", which consists in extending the safety outlet gas channel 13.1 above the level of the outer heat-insulating jacket 5.

The control unit 15.1 will further solve the ongoing evaluation of changes in pressure loss during gas flow in the high-temperature storage space 14. For this activity, the control unit 15.1 will be connected to the flow and differential pressure meter 15.7, measuring the pressure difference between the gas in the first outlet channel 10.1 and the gas in the technological space 4.2, during the operation of the heat input heat exchange circuit 9.1, or between the gas in the second connecting channel 10.3 and

- 15 CZ 2023 - 173 A3 by gas in the technological area 4.2, during the operation of the input heat exchange circuit 9.3 heat with electric heating.

Handling bulk refractory material

When the above-standard pressure loss is measured, the need for replacement (reconditioning) of bulk refractory material 1 will be signaled. The replacement will be initiated by the activity of the collection and transport system 21 of the material to be repaired, under at least one hopper 21.1. The operation of the collection and transport system 21 of the material to be overhauled will make it possible to dump, partially or completely, the bulk refractory material 1 from the high-temperature storage space 14. In the case of large floor plan storage areas, it will be appropriate to design several hoppers 21.1 so that the sloping walls of the hopper 21.1, with a sufficient slope too did not increase the necessary height of the service space. During the uniform removal of bulk refractory material 1, the material slides evenly across the entire cross-sectional area of the high-temperature storage space 14 through the grate with gas channels 17, and the height of the hot gas layer 14.6 increases. It is then possible to fill the space created in the hot gas layer 14.6 with at least one distribution valve 16, new or refurbished loose refractory material 1.

The distribution valve 16 and its functionality is described in Fig. 5. The uniform distribution of particles of bulk refractory material around the distribution valve 16 will be ensured by the vibrating plate 18, fixed on the lower side of the inner body of the distribution valve 17.6 in the area of the hot gas layer 14.6. In the vibrating plate 18, there will be evenly spaced holes allowing particles to fall into the space under the vibrating plate 18. The vibrating plate 18 will be slightly inclined from the mouth of the distribution valve 16 to the edges, and thus the particles will be distributed over its entire surface until the holes are filled, without the possibility of retention of particles in the mouth of the distribution valve 16 before almost completely filling the space around the perimeter of the vibrating plate 18. The eccentricity of the vibrations of the plate defined by the accelerometer 15.9 will signal the degree of its contact with the grains of the bulk refractory material 1. The eccentricity of the vibrations is understood as the range of extreme positions during oscillation of the plate, i.e. at constant energy exciting vibrations, the amount of acceleration of the mass of the plate during oscillating motion will decrease with the growth of the number of particles in contact with the oscillating plate. With a high degree of contact of particles with the vibrating plate 18, the eccentricity of the movement of the vibrating plate 18 will be reduced, and this will signal the state of filling of the high-temperature storage space 14. The vibrating plate 18 must be made of the appropriate refractory material due to the working temperatures and mechanical load.

Bulk refractory material 1 intended for replenishment can be transported to at least one distribution valve 16 using the bulk material transport system 19 and the replenishment channel 19.3 with a sufficient slope for the free movement of particles driven by gravity or vibrations. In the case of a system with more than one distribution valve 16, the bulk material transport system 19 will be supplemented with a distributor 19.1 with a servo drive 19.2 of the distributor, controlling the distribution of particles into the individual distribution valves 16.

Especially during the operation of the heat input heat exchange circuit 9.1, and thus during the storage of thermal energy in the storage, the gas flow can carry separated dust particles. This is due to the erosive action of large changes in temperature and associated changes in particle size. The flow of gas through the bulk refractory material 1 will be terminated on the lower side of the high-temperature storage space 14 by the entry of gas into the space of the grate with gas channels 14.7. From there, the gas will be led to at least one dust separator 20.1 before entering the gas gap 4.1. Advantageously, the dust separator 20.1 will have a cyclone design, ensuring maximally uniform and minimal pressure loss. In order to catch even very fine particles, the cyclone dust separator 20.1 can be equipped with a filter with the possibility of recovery, and a differential pressure sensor 20.2, connected to the control unit 15.1 (An effective way of recuperating the filter can be ensured by supplementing it with a vibrator and activating it, in case of a weak counterflow resulting from the activity of the output heat exchange circuit 9.2 heat).

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Below the high-temperature accumulation space is the service space 22. This space is intended for maintenance, or operation, of the collection and transport system 20 of separated dust, at least one dust separator 20.1 and the collection and transport system 21 of material to be overhauled. In particular, with a larger floor plan area of the storage, an automated implementation of collection and transport systems is suitable, when only occasional service intervention for equipment maintenance will be necessary. The service space 22 will preferably be included in the space isolated by the outer heat-insulating jacket 5. The temperature in the service space 22 may reach a level that does not allow direct human service during normal storage operation. For service intervention, it will be necessary to reduce the temperature in this space to an acceptable level for human service. This will be achieved by opening the two-way valve 13, which will ensure the removal of cooled gas (for human operation it can be a high temperature), and, if necessary, the supply of ambient air. To make it easier to maintain an acceptable temperature for human service, the ceiling of the service space 22 will preferably be provided with thermal insulation of the service space 5.2.

Distribution valve function

Fig. 5 schematically shows the breakdown of the distribution valve and its working position.

An exemplary solution describes the addition of bulk refractory material 1 to the hot gas layer 14.6 above the high-temperature storage space 14 at operating temperature. An exemplary solution prevents the penetration of heat and ensures the safety of the valve when entering the area of high temperatures. In the exemplary solution of the distribution valve 16, an electromechanical solution is used. For a larger number of distribution valves 16, a similar solution can be provided in the form of a hydraulic system.

The distribution valve 16 includes a shell 17 of the distribution valve in the shape of a cylinder with a vertical axis, into which the top-up channel 19.3 is led at its upper end. Inside the shell 17 of the distribution valve in the shape of a cylinder, the shell 17.2 of the servo drive is built in the shape of a cylinder with a smaller outer diameter (at least 6 times the diameter of the particles), in which the upper part 17.3 of the inner body of the distribution valve with the spring hinge 17.8 moves. The movement is provided by the servo drive 15.3 of the valve and the brake 17.9 of the displacement. On the upper part 17.3 of the inner body of the distribution valve, a movable part of the primary closure 17.4 of the distribution valve is fixed from the outside, which in the closed state (in the upper position) fills the space between the housing 17 of the distribution valve and the housing 17.2 of the servo drive. The upper part 17.3 of the inner body of the distribution valve is separated from the lower part 17.6 of the inner body of the distribution valve by the vibration damper 17.5 under the connection of the primary closure 17.4 of the distribution valve. The lower part 17.6 of the inner body of the distribution valve has the shape of a conical section with a wide horizontal base on the lower side and a narrow upper part connected to the vibration damper 17.5, it is made of solid heat-insulating material (e.g. porous ceramics). A vibrator 15.8 and an accelerometer 15.9 are fixed inside the lower part 17.6 of the inner body of the distribution valve, at its upper end with minimal temperature influence. A thermal fuse 15.6 is placed inside the housing 17 of the distribution valve at the highest point of attachment of the vibrator 15.8.

The cover 17 of the distribution valve on the lower side passes into the insulating cover 17.1 of the distribution valve, copying the outer surface of the lower part 17.6 of the internal body of the distribution valve. The insulating shell 17.1 of the distribution valve passes through the outer heat-insulating shell 5, the gas gap 4.1, the supporting inner shell 3, and the high-temperature thermal insulation 2. In the levels of the layers of the high-temperature thermal insulation 2, rings of sealing insulating material are fitted into the grooves in the insulating shell 17.1 of the distribution valve . At the level of the gas gap 4.1, there are holes in the insulating casing 17.1 of the distribution valve, connecting the gas gap 4.1 with the sealing gap formed in the intermediate position 16.2 of the distribution valve and the open distribution valve 16.3. The size of the openings will be just large enough so that the flow of cooled gas from the thus connected gas gap 4.1 into the hot gas layer 14.6, created by the pressure difference during the operation of the heat output heat exchange circuit 9.2, sufficiently blocks the spread of heat to the upper part of the distribution valve 16. The spring suspension 17.8 will act to the connected upper part 17.3 of the internal body of the distribution valve and the lower part 17.6 of the internal body of the distribution valve, further connected to

- 17 CZ 2023 - 173 A3 by the vibrating plate 18, with sufficient force to compensate for their combined weight and, in addition, exert sufficient sealing pressure on the insulating shell 17.1 of the distribution valve.

The distribution valve 16 will perform its function by vertical movement of the lower part 17.6 of the inner body of the distribution valve and other tightly connected parts, in particular the primary closure 17.4 of the distribution valve, the upper part 17.3 of the inner body of the distribution valve, the vibration damper 17.5, the vibrator 15.8 and the accelerometer 15.9. The vertical movement is ensured by the valve servo drive 15.3, the displacement brake 17.9 and the spring hinge 17.8.

The distribution valve 16 has three working positions. In the first position, the closed distribution valve 16.1, the lower part 17.6 of the internal body of the distribution valve rests on the seal in the insulating shell 17.1 of the distribution valve and the primary closure 17.4 of the distribution valve is closed. The closure of the primary closure 17.4 of the distribution valve does not have to be tight, it only has to stop the movement of particles of loose refractory material 1.

In the second working position, the intermediate position 16.2 of the distribution valve, there is a gap between the lower part 17.6 of the inner body of the distribution valve and the insulating shell 17.1 of the distribution valve, allowing, with a margin, the free passage of particles of loose refractory material 1, but not allowing their passage through the primary closure 17.4 of the distribution valve.

In the third position, the open distribution valve 16.3, the primary closure 17.4 of the distribution valve will already be opened, and the particles of loose refractory material 1 will fall through the distribution valve 16 into the space of the hot gas layer 14.6. When closing the distribution valve 16, the primary closure 17.4 of the distribution valve is closed first.

The servo drive 15.3 of the valve is designed in such a way that when the power supply is interrupted (even in the case of a random emergency), an external force will enable its closure, by interrupting the voltage supply to the magnetic clutch 16.4 of the distribution valve. The valve closing time between the phase of the intermediate position 16.2 of the distribution valve and the reduction of the gap between the insulating jacket 17.1 of the distribution valve and the lower part 17.6 of the internal body of the distribution valve below the particle size dimension of the bulk refractory material 1 must be sufficient for the passage of particles from the primary closure 17.4 of the distribution valve into the hot gas space layers 14.6. If there is sufficient free space in the hot gas layer 14.6, the particles of loose refractory material 1 will not get stuck inside the distribution valve 16. The size of the inlet opening from the replenishment channel 19.3 to the distribution valve 16 is only large enough so that the open distribution valve 16.3 cannot become clogged.

In the exemplary solution of the distribution valve 16, the adjustable closing speed is ensured by a combination of the hydrodynamic brake 17.9 of the displacement and the spring hinge 17.8. The closing of the valve also occurs when the temperature inside the casing 17 of the distribution valve rises above the design limit, when the thermal fuse 15.6 is activated to shut down the electrical supply. Disengagement of the magnetic clutch 16.4 of the distribution valve causes disconnection of the servo drive from the upper part 17.3 of the internal body of the distribution valve, and thus the slow closing of the valve, given by the fixed setting of the brake 17.9 of the displacement. The vibration damper 17.5 separates the static part of the valve from the vibrating lower part 17.6 of the inner body of the distribution valve.

Industrial applicability

High-temperature heat storage can be used to transfer the heat of a gas medium that is stable and chemically unreactive even at high temperatures, such as nitrogen or air. Thermal energy can be stored in bulk refractory material.

Claims (11)

1. A system for storing and transferring heat, including a. at least one heat source for generating heat energy; b. high-temperature heat storage with bulk refractory material (1) filling the high-temperature storage space (14) for storing the generated thermal energy; c. at least one heat consumption system for the use of stored heat energy; and d. heat transfer mechanism for transferring heat from the heat source to the high-temperature heat storage and from the high-temperature heat storage to the heat consumption system, the heat transfer mechanism being a closed gas circuit connecting the heat source, the high-temperature heat storage and the heat consumption system, the high-temperature heat storage being partially sheathed with a supporting inner casing (3), characterized in that the loose refractory material (1) includes a fraction of particles with a sphericity in the range of 0.4 to 1 and with an average particle size in the range of 0.5 to 20 mm, while the volume ratio of the largest and of the smallest particles is a maximum of 5:1, while the supporting inner shell (3) is covered with an outer heat-insulating shell (5) so that there is a gas gap (4.1) between the supporting inner shell (3) and the outer heat-insulating shell (5) ) for the recovery of heat losses from the high-temperature heat storage penetrating through the supporting inner shell (3), while the gas gap (4.1) together with the connecting gas channel (4.3) connects the high-temperature heat storage with at least one technological space (4.2), which is further connected to by at least one heat consumption system, wherein the hot gas channel (7) connects the high-temperature heat storage with at least one heat source. 2. The system according to claim 1, characterized in that the supporting inner shell (3) contains high-temperature thermal insulation (2) on the side adjacent to the high-temperature storage space (14). 3. A system according to any one of the preceding claims, characterized in that the heat source is an input heat exchanger (11), while a blower system (10) is arranged in the technological space (4.2) for conducting cooled gas from the high-temperature storage space (14) through a gas gap (4.1), a connecting gas channel (4.3), a technological space (4.2) and a first outlet gas channel (10.1) to at least one input heat exchanger (11), whereby it is arranged to conduct hot gas from the input heat exchanger (11) at least one hot gas channel (7) led from the inlet heat exchanger (11) to the gas layer (14.6) above the high-temperature accumulation space (14); and/or that the heat source is at least one electrically heated body (8.2), while a blower system (10) is arranged in the technological space (4.2) for conducting cooled gas from the high-temperature storage space (14) through the gas gap (4.1), connecting gas channel (4.3) and technological space (4.2) into the second connecting gas channel (10.3) and hot gas channel (7), and further in thermal contact with the electrically heated body (8.2) for heating the gas into the gas layer (14.6) above the high-temperature storage space (14), whereby the electrically heated body (8.2) is arranged inside the supporting inner shell (3) outside the high-temperature accumulation space (14), preferably in the hot gas channel (7); and further that the heat transfer system is the output heat exchanger (12), while in the technological space (4.2) a blower system (10) is arranged for guiding the cooled gas from the output heat exchanger (12) through the second input gas channel (10.2), technological space (4.2), a connecting gas channel (4.3) and a gas gap (4.1) to the high-temperature storage space (14), whereby at least one hot gas channel (7) leading from the gas layer is arranged for conducting hot gas from the high-temperature storage space (14) (14.6) above the high-temperature storage space (14) into at least one outlet heat exchanger (12). - 19 CZ 2023 - 173 A3 4. A system according to any one of the preceding claims, characterized in that the first gas inlet channel (11.1) and the first gas outlet channel (10.1) are arranged coaxially with each other such that the first gas outlet channel (10.1) surrounds the first gas inlet channel (11.1) ); and/or that the second inlet gas channel (10.2) and the second outlet gas channel (12.1) are arranged coaxially with each other such that the second inlet gas channel (10.2) surrounds the second outlet gas channel (12.1); and/or that the connecting gas channel (4.3) and the hot gas channel (7) are arranged coaxially with each other, so that the connecting gas channel (4.3) surrounds the hot gas channel (7). 5. System according to any one of the preceding claims, characterized in that the gas gap (4.1) is connected via an air channel (13.3) to a two-way valve (13), while the two-way valve (13) is further connected to the environment via a safety inlet gas channel (13.2) and safety outlet gas channel (13.1). 6. A system according to any of the preceding claims, characterized in that the bulk refractory material (1) is any of the group comprising basalt, andesite, dacite, artificial sintered aggregate, ceramic material, blast furnace slag, pressed graphite with glassy carbon on the surface, carbide and nitride. 7. System according to any one of the preceding claims, characterized in that in the first gas inlet channel (11.1), in the first gas outlet channel (10.1), in the second gas inlet channel (10.2), in the second gas outlet channel (12.1), in the area of the inlet-outlet (6) of the cooled gas, in the area of the connection of the well (8.1) of the electrically heated body (8.2) on the gas layer (14.6) above the high-temperature accumulation space (14) and in the area of the hot gas channel (7) before entering the well (8.1) a temperature sensor (15.2) is arranged, while each temperature sensor (15.2) is connected to the control unit (15.1). 8. System according to any one of the preceding claims, characterized in that a service space (22) is arranged under the high-temperature storage space (14) for the location of the collection and transport system (20) of separated dust and/or for the location of the collection and transport system (21 ) of the material to be overhauled. 9. System according to any one of the preceding claims, characterized in that at least one distribution valve (16) opens into the hot gas layer (14.6) above the high-temperature storage space (14) for the input of bulk refractory material (1) at the operating temperatures of the high-temperature heat storage . 10. System according to any one of the preceding claims, characterized in that the average particle size is in the range from 0.5 mm to 20 mm, while the ratio of the average particle size of the bulk refractory material (1) to the total height of the high-temperature accumulation space (14) is in the range of 1:1500 to 1:6000. 11. A method of heat storage and transfer using a system according to any one of the preceding claims, wherein the high-temperature heat storage is partially sheathed with a supporting inner shell (3) and the supporting inner shell (3) is sheathed with an outer heat-insulating shell (5) such that between the supporting a gas gap (4.1) is located between the inner jacket (3) and the outer heat-insulating jacket (5), and the mentioned method includes the following heat storage steps: a. generation of thermal energy in at least one heat source to produce hot gas; b. transfer of hot gas from the heat source to the high-temperature heat storage using a mechanism - 20 CZ 2023 - 173 A3 of heat transfer in the form of a closed gas circuit; c. storing the generated thermal energy from the hot gas in a high-temperature heat storage with bulk refractory material (1) contained in the high-temperature storage space (14) to produce cooled gas; d. transfer of cooled gas from the high-temperature heat storage to the heat source using a heat transfer mechanism in the form of a closed gas circuit; and e. optionally repeating steps a. to d.; wherein said method further comprises the following steps of consumption of stored heat: f. transfer of cooled gas from the heat consumption system to high-temperature heat storage using a heat transfer mechanism in the form of a closed gas circuit; g. obtaining stored thermal energy from a high-temperature heat storage with bulk refractory material (1) contained in a high-temperature storage space (14) to generate hot gas; h. transfer of hot gas from high-temperature heat storage to the heat consumption system using a heat transfer mechanism in the form of a closed gas circuit; i. consumption of stored heat energy from hot gas in at least one heat consumption system; characterized in that the bulk refractory material (1) includes a fraction of particles with a sphericity in the range of 0.4 to 1 and with an average particle size in the range of 0.5 to 20 mm, while the volume ratio of the largest and smallest particles is a maximum of 5:1, whereas in steps d. and f. the heat losses escaping from the high-temperature heat storage, caused by heat permeation through the supporting inner shell (3) surrounding the high-temperature heat storage, are recovered by passing the cooled gas through the gas gap (4.1) arranged between the supporting inner shell (3) and an outer heat-insulating shell (5) surrounding the supporting inner shell (3).