Materials and their manufacture for use as storage media in sensitive energy storage systems in the low, medium and high temperature range

Abstract

The invention relates to a modified red mud or modified bauxite residue and a method for its production and numerous uses of the modified red mud as a storage medium, in a thermal accumulator and the modified red mud as a storage medium, especially in a thermal accumulator. Herein, the modified red mud comprises the following composition: hematite (Fe2O3), corundum (Al2O3), rutile (TiO2) and / or anatase (TiO2), quartz (SiO2), optionally perovskite (CaTiO3), optionally geikielite ((Fe 3+ ,Fe 2+ )2(Ti,Fe 3+ )O5) and / or nepheline ((Na,K)[AlSiO4]) perovskite (CaTiO3). Thereby, a new material is provided and its production is described for use as a storage medium in sensitive energy storage systems in the low, medium and high temperature range.

Description

[0001] This invention relates to modified red mud, or modified bauxite residue, hereinafter also referred to as ALFERROCK. ® And its manufacturing methods and uses.

[0002] Germany's Renewable Energy Sources Act (EEG) mandates the phase-out of nuclear and coal-fired power by 2038. Wind farms, solar power systems, and biogas plants are expected to be the alternatives to power generation in Germany.

[0003] However, wind farms and solar power systems, in particular, have the disadvantage of not generating electricity in windless or dim conditions. Therefore, renewable energy sources cannot provide baseload power for users, especially industrial users, who rely on a stable power supply.

[0004] To address this systemic deficiency, energy generation and energy consumption must be decoupled. Only when energy storage devices connected between energy generators and energy users provide a consistent power flow in the required manner can renewable energy serve as baseload power.

[0005] Therefore, people need energy storage devices and suitable storage media that can address the shortcomings of obtaining energy from renewable energy sources and can themselves be obtained in a cost-effective way to conserve resources.

[0006] It is known that red mud is generated as waste in the Bayer process for extracting aluminum hydroxide (ATH) from bauxite. Hereinafter, red mud (RS) refers to the residue generated in the Bayer process during the extraction of ATH from bauxite. A large portion of the bauxite residue or red mud generated during aluminum extraction is not further processed or economically viable, but is instead disposed of in landfills.

[0007] It is known from existing technology that bauxite residues are suitable as adsorbents due to their large internal surface area.

[0008] It is also known that modified bauxite residue, due to its chemical composition, can be used as a halogen-free inorganic fire retardant in all types of plastics, and is available in compound or foam form (WO 2012 / 126487 A1).

[0009] It is also known that modified bauxite residue has a high density, so this composition can also be used as a sound insulation material or as a weighting agent for drilling mud or as a radiation shield (WO 2014 / 114283 A1).

[0010] Additionally, WO 2005 / 061408 A1 discloses a porous particulate material containing bauxite residue for fluid handling and contaminant removal. Contaminants include, for example, heavy metals, anions, and gases.

[0011] In experiments conducted with modified chromium-depleted bauxite residue heated to temperatures between 120°C and 250°C, the inventors found that the cooling process proceeded unexpectedly slowly. Based on these observations, the inventors conducted extensive research on the properties of (optionally chromium-depleted) bauxite residue or red mud, subjecting it to heat treatment while simultaneously observing chemical, mineralogical, and physical parameters, particularly thermodynamic parameters. Consequently, the inventors obtained a novel modified red mud suitable as a storage medium, and especially as a heat accumulator.

[0012] The present invention relates to modified red mud as defined in any one of claims 1 and 3, a method for manufacturing modified red mud having the features of claim 10, a storage medium comprising modified red mud, a heat accumulator comprising the storage medium, and numerous uses of modified red mud as a storage medium, particularly in heat accumulators.

[0013] In one embodiment, a modified red mud comprises the following components: hematite (Fe2O3), corundum (Al2O3), rutile (TiO2) and / or anatase (TiO2), quartz (SiO2), optional perovskite (CaTiO3), and optional brookite (Fe2O3). 3+ ,Fe 2+ )2(Ti,Fe 3+ (O5) and / or nepheline ((Na,K)[AlSiO4]).

[0014] Therefore, modified red mud may specifically contain, or consist primarily of, the following components: hematite (Fe2O3), corundum (Al2O3), rutile (TiO2) and / or anatase (TiO2) and quartz (SiO2). Other components are optional and not mandatory. As such other (optional) components, perovskite (CaTiO3) and brookite (Fe2O3) are particularly noteworthy. 3+ ,Fe 2 + )2(Ti,Fe 3+ (O5) and / or nepheline ((Na,K)[AlSiO4]).

[0015] In one embodiment, the modified red mud may contain 48-55 wt%, especially 49-54 wt%, especially 50-53 wt%, of hematite (Fe2O3), 13-18 wt%, especially 14-17 wt%, especially 15-16 wt%, of corundum (Al2O3), 8-12 wt%, especially 9-11 wt%, of rutile (TiO2) and / or anatase (TiO2), and 2-5 wt%, especially 3-4 wt%, of quartz (SiO2).

[0016] In one embodiment, a modified red mud is obtained by heating red mud having the following mineral composition to a temperature of at least 800°C, particularly at least 850°C, particularly at least 900°C, particularly at least 950°C, and preferably at least 1000°C: -10-55% by weight, especially 10-50% by weight iron compounds, -12-35% by weight aluminum compounds, -3-17% by weight, especially 5-17% by weight silicon compounds, -2-12% by weight, especially 2-10% by weight of titanium dioxide, -0.5-6% by weight of calcium compounds, and - Perhaps there are other unavoidable impurities.

[0017] The modified red mud obtained in this way can also be called heat-treated red mud or sintered red mud.

[0018] Modified red mud can be treated at a specified temperature for a period of 5 minutes to 36 hours, especially 5 minutes to 24 hours, especially 5 minutes to 12 hours, especially 5 minutes to 6 hours, especially 5 minutes to 2 hours, especially 5 minutes to 1 hour, especially 5 minutes to 30 minutes.

[0019] In one embodiment, the modified red mud may substantially lack one, two, three, or all four of the following components: - Boehmite (Al(OH)3), - Goethite (FeO(OH)), - Boehmite (AlO(OH)), - Calcite (Na6Ca2[(CO3)2|Al6Si6O) 24 ]).

[0020] In the sense of this application, "substantially none" can in particular mean a content of less than 0.5% by weight, especially less than 0.2% by weight, especially less than 0.1% by weight, and especially less than 0.05% by weight.

[0021] In one embodiment, the modified red mud can have a particle size distribution of 3.90-4.0 g / cm³. 3 Between 3.91 and 3.95 g / cm³ 3 Between 3.92 and 3.94 g / cm³ 3 Between, especially at approximately 3.93 g / cm³ 3 The density.

[0022] In one embodiment, the modified red mud may have an average particle size d50 between 3 and 10 μm, particularly between 5 and 8 μm. The average particle size d50 can be determined, in particular, by means of laser diffraction techniques or by laser diffraction techniques (MALVERN) according to ISO 13320 (2009).

[0023] In one embodiment, the modified red mud may have a particle size d10 between 0.5 and 2.5 μm, particularly between 1.0 and 2.0 μm, and / or a particle size d90 between 15 and 50 μm, particularly between 20 and 40 μm. The particle size d10 and particle size d90 may be determined, in particular, by means of laser diffraction techniques or by laser diffraction techniques (MALVERN) according to ISO 13320 (2009).

[0024] In one embodiment, the modified red mud can have a molecular weight distribution of 0.6-0.8 kJ / (kg·kg·℃). * Between 0.65 and 0.75 kJ / (kg K), especially between 0.65 and 0.75 kJ / (kg K). * Specific heat capacity at 20℃ between K) and / or 0.9-1.3 kJ / (kg) * Between 0.95 and 1.2 kJ / (kg K), especially between 0.95 and 1.2 kJ / (kg K). * The specific heat capacity at 726.8°C (K). The specific heat capacity can be determined in particular according to DIN EN ISO 11357-4.

[0025] In one embodiment, the modified red mud can have a concentration of 3-35 W / (m³). * Between K), especially in the range of 5-20 W / (m * Specific thermal conductivity (T) between K and 2000 K. Specific thermal conductivity can be determined, in particular, by means of a plate test specimen in a λ measuring instrument according to DIN ISO 8302.

[0026] In one embodiment, the modified red mud can exist in the form of a pressed solid material.

[0027] A method for producing modified red mud includes heating red mud having the following mineral composition to a temperature of at least 800°C, particularly at least 850°C, particularly at least 900°C, particularly at least 950°C, and preferably at least 1000°C: -10-55% by weight, especially 10-50% by weight iron compounds, -12-35% by weight aluminum compounds, -3-17% by weight, especially 5-17% by weight silicon compounds, -2-12% by weight, especially 2-10% by weight of titanium dioxide, -0.5-6% by weight of calcium compounds, and - Perhaps there are other unavoidable impurities.

[0028] In one embodiment, the modified red mud can be treated at a specified temperature for a period of time, particularly for 5 minutes to 36 hours, particularly for 5 minutes to 24 hours, particularly for 5 minutes to 12 hours, particularly for 5 minutes to 6 hours, particularly for 5 minutes to 2 hours, particularly for 5 minutes to 1 hour, particularly for 5 minutes to 30 minutes.

[0029] In one embodiment, the modified red mud according to the present invention can be produced in the method of producing modified red mud.

[0030] In one embodiment, the method may further include pressing (sintering or heat-treating) red mud after heating.

[0031] The storage medium includes the modified red mud according to the present invention. The term "storage medium" in the context of this application can specifically refer to an active (or actual) storage material. For example, in the case of a heat accumulator, the storage medium can be a heat storage material, which must have the appropriate (or suitable) heat capacity and thermal conductivity.

[0032] The storage medium may contain other components besides modified red mud.

[0033] In one embodiment, the storage medium may further comprise one or more of the following components: - This is used to avoid air entrainment (air absorption within the storage medium) and / or air adsorption (air accumulation on the surface). (For example, the substrate for an electric / thermal accumulator can be processed at maximum power (e.g., with successive rotary vacuum pumps) using a twin-screw extruder with the addition of 5-10% by weight of a polydimethylsiloxane polymer and simultaneous vacuum degassing, so that all air entrainment is eliminated by strong dispersion within the polysiloxane system. The resulting material is soft.) - Substances used to improve thermal conductivity, particularly those selected from the group consisting of metal colloids, metal powders, graphite, and silicon-containing materials. - Substances used to form thixotropic compositions. (Especially by adding polypentaerythritol and carboxylic acids (such as C18) to the heat-carrying substrate prior to processing in a twin-screw extruder, the substrate can be thixotropically modulated, for example, over a wider range. During the activation process of the current / heat accumulator, i.e., during slow heating, these reagents, in addition to polysiloxanes, can also be pyrolyzed into carbon, where the resulting carbon does not adversely affect the desired performance of the current-heat accumulator but rather improves thermal conductivity).

[0034] The heat accumulator includes the storage medium according to the invention. In the context of this application, "heat accumulator" can specifically refer to a device that contains the storage medium as an active heat storage material and may also have other equipment components.

[0035] In one embodiment, the heat storage device may be an electric current / heat storage device. In the context of this application, "electric current / heat storage device" specifically refers to a storage device that can convert electrical energy into heat energy and / or heat energy into electrical energy, and in particular, can convert not only electrical energy into heat energy but also heat energy into electrical energy.

[0036] In one embodiment, the heat accumulator may further include means for charging and discharging the heat accumulator. The means for charging and discharging the heat accumulator may be, for example, mechanical components such as openings, conveying mechanisms, or transport mechanisms, and / or other components such as conductive contacts or terminals, and especially conductive contacts or terminals and / or thermally conductive contacts or terminals.

[0037] In one embodiment, the heat storage device can be an electric current / heat storage device, which also includes a resistance wire. This allows for the conversion of electrical energy to thermal energy, particularly within the electric current / heat storage device. The resistance wire can be in direct or indirect contact with the storage medium.

[0038] The present invention also relates to the use of the modified red mud according to the invention as a storage medium, particularly in heat accumulators.

[0039] In one embodiment, modified red mud can be used for heat storage at temperatures up to 1000°C, particularly above 100°C up to 1000°C. However, it is also feasible to use it for heat storage at temperatures above 80°C, particularly above 90°C.

[0040] In one embodiment, modified red mud can be used as a storage medium for reheating and cooling (or in a reheating and cooling accumulator).

[0041] In one embodiment, modified red mud can be used as a storage medium that can be heated and cooled simultaneously.

[0042] In one embodiment, modified red mud can be used as a storage medium in an electric current-heat storage device.

[0043] In one implementation, the storage medium can be heated by means of an electric current and / or cooled when an electric current is generated.

[0044] In one embodiment, the modified red mud can be used to store electricity generated from renewable energy sources. "Renewable energy sources" in this application can specifically refer to wind, hydro, tidal, solar, geothermal, and biomass, but the latter are preferred because their temporal generation is largely unaffected by human activity, making effective storage particularly meaningful, especially wind, tidal, and solar energy.

[0045] In one embodiment, the current-thermal storage device may include a resistance wire that is heated by an electric current and thus heats the storage medium.

[0046] In one embodiment, the thermal energy stored in the storage medium can be transferred to other media, thereby cooling (releasing energy) the storage medium. Here, the other media are particularly selected from the group consisting of water, salt solutions such as ionic liquids, and hot oil.

[0047] In one embodiment, the storage medium and the energy dissipation device may be integrated or separate components.

[0048] In one implementation, the current-thermal storage device can be used to deliver electrical energy after current-thermal coupling is completed, without a wiring system.

[0049] In one implementation, the current-thermal storage device can generate current again after thermal-current coupling.

[0050] In one implementation, the current-thermal storage device can be used to supply energy to isolated energy-consuming devices.

[0051] In one implementation, the isolated energy-consuming device can be supplied with both thermal and electrical energy.

[0052] In one implementation, the current-thermal energy storage device can be used to supply energy to machines or mobile devices such as vehicles.

[0053] Other tasks and advantages of the embodiments of the present invention will become clear in conjunction with the following detailed description and accompanying drawings.

[0054] Figure 1 The particle size distribution of a common dry bauxite residue is shown.

[0055] Figure 2 The density curves of red mud samples heated from 100°C to 1000°C in an oxygen (O2) atmosphere or a nitrogen (N2) atmosphere are shown.

[0056] Figure 3 The particle size distribution of red mud heated to 1000°C is shown according to an exemplary embodiment of the present invention.

[0057] Figure 4 Table 3 shows an ALFERROCK for use in an exemplary embodiment of the present invention. ® The specific heat capacity test series curves.

[0058] Further details and other embodiments of the present invention will be described below. However, the present invention is not limited to the specific description below, but is only used to illustrate the teachings of the present invention.

[0059] It should be noted that features described with respect to one exemplary embodiment or exemplary subject matter can be combined with each other exemplary embodiment or each other exemplary subject matter. In particular, features described with respect to one exemplary embodiment of the modified red mud of the present invention can be combined with each other exemplary embodiment of the modified red mud of the present invention and with each exemplary embodiment of the modified red mud manufacturing method, storage medium, heat accumulator and use of modified red mud, and vice versa, unless otherwise expressly stated.

[0060] When a term is referred to in the singular with indefinite or definite articles such as “a,” “one,” “the,” or “the,” it also includes terms in the plural, and vice versa, unless the context explicitly specifies otherwise. The words “including” or “having,” as used herein, not only include the meaning of “containing” or “comprising,” but can also mean “consisting of” and “essentially composed of.”

[0061] The research performed within the scope of this invention first involves characterizing the substance under study at room temperature, particularly determining its chemical and mineralogical composition at room temperature. Furthermore, the substance is slowly heated to 1000°C, in which case its mineralogical phases, density, and specific heat capacity are measured every 100°C.

[0062] The characteristics of the substance under study are: 1. Chemical composition (typically used for bauxite residue) • 10-50% by weight of iron compounds • 12-35% by weight aluminum compounds • 5-17% by weight of silicon compounds • 2-10% by weight of titanium dioxide • 0.5-6% by weight of calcium compounds 2. Mineralogical composition The mineral phases determined by X-ray imaging were determined under the initial conditions of the experiment: • Hematite • Goethite • Anatase Rutile • Perovskite •Boehmite • Boehmite • Calecene •quartz 3. Particle size Particle diameter (μm) as Figure 1As shown. This substance is very fine and exhibits three extreme values. Under good dispersion conditions, this substance is expected to have a high density because it can incorporate fine crystals into the voids between medium-fine and coarse crystals. The measured density is 3.63 g / cm³. 3 This confirms the estimate.

[0063] 4. Implementation of the test The test material samples were gradually heated to 1000℃ under oxygen and nitrogen conditions. The samples were then removed at 100℃, 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃ and 1000℃ respectively, and the changes in mineralogical composition and density were determined.

[0064] Specific heat capacity was measured over a temperature range from room temperature (30.26°C) to 584.20°C.

[0065] 5. Interpretation of Results 5.1. Mineral phases The mineralogical composition of this substance changes with temperature (see Table 1 below).

[0066] Boehmite decomposes at about 300℃, goethite at about 400℃, and boehmite at 500℃.

[0067] Above 600℃, CO2 release occurs in nepheline Na6Ca2[(AlSiO4)6(CO3)2]. The first maximum density occurs at 600℃. This material here is mainly composed of hematite (Fe2O3) and corundum (Al2O3) with small amounts of TiO2, nepheline, and perovskite.

[0068] At 1000℃, nepheline and two TiO2 phases, namely anatase and rutile, transform into the mineral argillaceous iron oxide [(Fe 3+ )2Ti]O5 and nepheline [(Na,K)[AlSiO4].

[0069] Table 1: Mineral phase bauxite residue (bulk density 0.944 g / cm³) 3 )

[0070] 5.2. Density like Figure 2 As shown, the density as a function of temperature is 3.63 (g / cm³) at 100°C. 3 ) developed to 3.93 (g / cm) at 1000℃ 3 The mineral phase decomposition accompanying the removal of water and CO2, along with the sintering process, sequentially decreases density between 600℃ and 700℃, until it increases again to 3.93 (g / cm³) at 1000℃. 3 ).

[0071] For applications in the field of thermal engineering, only the following substances can be used: they are stable as physical substances and do not release other gases such as H2O or CO2 within their respective arbitrary temperature ranges, nor do they undergo further sintering processes. Oxides such as Fe2O3, Al2O3, TiO2, or SiO2 show almost no significant change with increasing temperature. The fact that the density of this substance remains constant when heated to 1000℃ and also remains constant during cooling reveals important characteristics of this substance, such as the absence of rehydration.

[0072] 5.3. Particle size Heating the material of the present invention to a temperature of 1000°C, for example, causes the particle diameter to shift to a significantly larger value due to the decomposition of hydroxides, oxide hydrates, or carbonates, and the sintering process (see...). Figure 3 Therefore, for example • The d10 value increased from 0.074 μm to 1.341 μm. • The d50 value increased from 0.261 μm to 6.743 μm. • The d90 value increased from 1.692 μm to 28.17 μm.

[0073] 5.4. Specific heat capacity The specific heat capacity of this substance is a function of temperature. As temperature increases, the specific heat capacity also increases. Table 2 below shows corresponding examples.

[0074] Table 2: Specific heat capacity at different temperatures

[0075] In a mixture, specific heat capacity is the sum of the specific heat capacities of each component in the mixture.

[0076] The usable materials are characterized as mixtures of various different mineral substances. Upon heating, these substances partially decompose, for example, through the cracking of water or CO2, forming oxides or other chemically stable mineral phases. A sintering process also occurs.

[0077] The measured value of this substance is 0.791 kJ / kg*K at 30℃ and 1.037 kJ / kg*K at 584℃. At 1000℃, the value can be extrapolated to 1.14-1.18 kJ / kg*K (see...). Figure 4 ).

[0078] Table 3: Specific Heat Capacity of Test Series ALFERROCK ®

[0079] When a substance heated to 1000°C cools down, cp The values ​​revert to those corresponding to their respective temperatures. However, because the initial material has been altered by mineral phase decomposition and the formation of other substances, and has also undergone sintering, the material has a different specific heat capacity after cooling compared to the initial material. It is important to determine that heating provides a stable material that can be heated and cooled arbitrarily frequently without undergoing further changes in the individual substances within the mixture. As mentioned above, this also applies to density.

[0080] 5.5. Specific thermal conductivity The thermal conductivity of a system depends in particular on many parameters such as pressure, temperature, mineralogical composition, porosity, and density.

[0081] By heating the usable material, as shown, all the non-thermally stable components are decomposed. After heating, a substance exists consisting of corundum (Al₂O₃), hematite (Fe₂O₃), rutile, and anatase (TiO₂), as well as refractory materials such as brookite [(Fe...]]. 3+ It is composed of 2Ti]O5 or nepheline [(Na,K)[AlSiO4].

[0082] Table 4 below shows the values ​​of thermal conductivity and density of the following substances, which indicate the most important components of the heated substance.

[0083] Table 4: Thermal conductivity and density of some components

[0084] During the heating process, the particle diameter of the resulting material increases significantly, while the surface area decreases. Consequently, the conductivity within the primary crystal also increases to the values ​​shown in Table 4.

[0085] The mixture also contains air, which, as a weak thermal conductor, reduces the measured thermal conductivity. Various methods have been proposed to avoid this effect, including the use of pressure, i.e., compressing the object into a solid state.

[0086] Additionally, the following substances can be added to prevent air inclusions between crystals or on the crystal surface, thereby enabling the creation of hard material blocks.

[0087] For example, the following fall into this category: • Metal colloids • Metal powder •graphite • Silicon-based sinterable pyrolytic materials In addition to adding the aforementioned substances, pressure and heat energy can also be used.

[0088] It is crucial to manufacture blocks of material with good thermal conductivity. Good thermal conductivity, especially the absence of air entrainment, is essential for both the charging (heating of the material) and releasing (transferring the stored heat to the system to generate steam) processes, so that the heated material can be used as a heat accumulator.

[0089] example A mixture of unheated and heated materials at a ratio of 1:1 is surface-modified with 5% PDMS (polydimethylsiloxane prepolymer) and fed into a BUSS kneading machine or a parallel twin-screw extruder. The compounding machine has a body temperature of 135°C and maximum vacuum degassing. The torque is adjusted to 65-85% of its maximum value. The material is removed via a cooling conveyor.

[0090] The resulting anhydrous and airless product is added to an isolation container and compacted. It is then slowly heated to 1000°C, thus preparing the accumulator for operation. Other materials such as metal dust, graphite, or salt solutions can be used instead of PDMS.

[0091] 6. Summary When heated to 1000°C, all components of the mixture that are unstable within this temperature range decompose. Boehmite, goethite, boehmite, and the nepheline and titanium dioxide phases belong to this category; under suitable conditions, they form argillaceous zeolite [(Fe...]] at 1000°C. 3+ )2Ti]O5 and nepheline [(Na,K)(AlSiO4)].

[0092] Upon cooling, a mixture is formed consisting of oxides such as Al2O3, Fe2O3, TiO2, SiO2, and possibly heat-resistant materials such as brookite and nepheline, which did not show further changes upon reheating to 1000°C.

[0093] Along with the aforementioned changes in the composition of the substance, the density also decreased from 3.63 g / cm³ at room temperature. 3 The concentration of 3.93 g / cm³ at 1000℃ changes. 3 The process is also expected to be accompanied by sintering. When the mixture heated to 1000°C is cooled, the density obtained at 1000°C remains unchanged because oxides such as Al2O3, Fe2O3, as well as TiO2 and SiO2, do not change their density in the temperature range of 25°C to 1000°C.

[0094] The sintering process and mineral phase decomposition cause the particle diameter in the mixture to shift towards the direction of increasing value. For example, d exists before heating. 50 =0.261μm and d 90 =1.692μm, and the following value can be measured after heating: d 50=6.743μm and d 90 =28.17μm. Increased particle size means smaller surface area and higher thermal conductivity. The air content (weak thermal conductivity) between very small crystals is reduced.

[0095] Studies characterizing the specific heat capacity of the material show that it increases from 0.79 kJ / kg*K at 25℃ to 1.037 kJ / kg*K at 600℃. At 1000℃, an extrapolated value of 1.14–1.18 kJ / kg*K is expected.

[0096] As already described, the density also increases, and the product of density and specific heat capacity, an important criterion for use as a heat storage device, reaches a value higher than that of water. Water has a density of 998.2 kg / m³ at 20°C. 3 It also exhibits a remarkable specific heat capacity of 4.182 (kJ / kg*K). Therefore, a volumetric heat capacity of 4175 (kJ / m³) is obtained. 3 K). The usable material has a density of 3890 (kg / m³). 3 ) and specific heat capacity of 1037 (kJ / kg*K) and, consequently, volumetric heat capacity at approximately 600℃ of 4.034 (kJ / m³) 3 K). A density value of 3930 (Kg / m³) was obtained at 1000℃. 3 ) and c p =1.16 (kJ / kg*K). Therefore, the volumetric heat capacity reaches a value of 4559 (kJ / m³). 3 K). This value is significantly higher than that of water.

[0097] The main difference between water and the specific substance described is the operating temperature of the storage medium. Water ideally operates in a temperature range between 40°C and 90°C, i.e., with a ΔT of 50°C, while the provided substance can operate in a temperature range up to 1000°C, meaning it can evaporate water from a temperature of 100°C and thus operate with a ΔT of 900°C. Therefore, the provided substance can store 15 to 20 times more heat than water.

[0098] In the storage medium, thermal conductivity is extremely important for both the charging (heating of the storage tank) and releasing processes. The thermal conductivity of the oxides primarily contained in the material ranges from 3 to 35 (W / m K). It is crucial for the accumulator to be able to compact the material used as the storage medium into a rigid mass where optimal heat flow can occur—from the heat sink into the storage medium, within the storage medium, and from the storage medium into the heat receiving system. In this regard, it is advantageous to eliminate gases with poor thermal conductivity, either within the material or on its surface. In addition to pressure, materials that "bind" the primary crystals can be added, including, for example, metal colloids, metal powders, graphite, and sinterable silicon-containing pyrolytic materials. Importantly, especially, is the fact that all unstable substances decompose during heating of the usable material to 1000°C, thus providing a primarily oxidizing, thermally stable storage medium that can be heated and cooled frequently without the generation of gases such as H₂O or CO₂ that could potentially damage the storage block.

[0099] Available materials for use as storage materials in high-temperature heat storage devices Savings system Water and solid substances, as described so far, belong to sensitive heat storage systems (sensitive because the heat in the storage device is perceptible).

[0100] A thermal storage unit can be heated via a thermo-mechanical coupling caused by electrical energy from a wind farm or solar power plant. In windless or dim conditions, the storage unit can generate steam to drive a turbine, which in turn generates electricity (thermo-mechanical coupling). The storage unit thus functions as an emergency current generator or, more commonly, a "backup power station." If this process is successful, it also allows for the simple and efficient design of power transmission lines.

[0101] The requirements for the accumulator are as follows: • High energy density • High power density •Low energy storage • Low loss •Low automatic energy release • Long cycle life • Long service life • Low investment cost • Low operating costs The available materials adequately meet the requirements.

[0102] The substance is •Inorganic, • Harmless • Durable, • Recyclable, •A large quantity is available. • Very economical, • Operates in a temperature range up to 1000℃. • It can charge and discharge energy simultaneously. • It can be easily manufactured.

[0103] In particular, the fact that available materials can simultaneously charge and release energy as sensitive high-temperature storage devices allows for the operation of controllable, permanently functioning energy storage power plants. This can compensate for functional deficiencies or meet higher demand requirements.

[0104] In addition, thermal storage devices can be used in wind farms or solar farms, where the energy generated can be used as baseload power in the form of a "slab configuration".

[0105] Additionally, small thermal storage units can be used, for example, for the entire energy supply of a room. These small units are heated, for example, by renewable energy sources and are then used as a conventional alternative to the complete energy supply, namely, for the heat and electricity supply of the room.

[0106] In addition, small heat storage units in all types of machines can be used for energy supply.

[0107] In addition, electrical energy can be converted into transportable energy in the form of a heat storage device in a wireless system after electro-thermal coupling.

[0108] In this way, the vehicle can also be powered. A heat accumulator, which can be replaced periodically like a battery, can drive an electric motor after successful thermo-electric coupling, similar to a lithium battery.

[0109] The device used to convert heat into electrical energy can be implemented as an integral part of the storage device, or in a separate unit.

[0110] example The usable material is filter cake, which must first undergo heat treatment, specifically by being slowly heated to 1000°C. At this point, the water content of the filter cake is first evaporated, and then the temperature is raised to 1000°C, calcining all minerals that are unstable at high temperatures. The material then consists only of oxides and stable inorganic phases such as nepheline or others. This material is then cooled and forms a storage medium.

[0111] The charging (i.e. heating) of the stored substance is achieved directly through the added resistance wire or heating element, specifically the resistance wire in the ceramic sleeve or other system. The stored substance can be continuously adjusted to any temperature via a corresponding control mechanism.

[0112] Energy release is achieved through a water circulation loop that passes through a stored substance at a suitable optimal (temperature range / vapor pressure) location. Water is evaporated, and the steam drives a turbine, generating an electric current. Excess steam is then returned to the water circulation loop via a cooling device ("cooling tower").

[0113] The optimal ratio between heat supply (hottest part) and heat loss can be adjusted by the specific thermal conductivity of the heat storage medium.

[0114] The heat storage material, heating device for supplying heat, and piping system (water) for consuming heat are combined into a single unit. This unit is externally insulated.

[0115] Importantly, the following description illustrates that such a thermal storage system can be simultaneously charged and discharged. Generally, energy storage hydropower stations are designed to be charged or discharged; see pump-storage hydropower stations for this purpose. With the possibility of simultaneous charging and discharging from renewable energy, stable energy storage power stations capable of serving as baseloads can be constructed.

[0116] The most important current thermal accumulator system used for sensitive thermal accumulators is water. This system is characterized by ideally operating water within a temperature range of 40-90°C, because water exists as steam above 100°C. That is, water has a ΔT of 50°C.

[0117] In contrast, a heat storage system that operates using a storage substance made from a usable material can operate at temperatures up to 1000°C. That is, the substance can evaporate water from temperatures above 100°C, thus operating at a ΔT of 900°C. In other words, this system belongs to the category of high-temperature storage systems.

[0118] example: Sensitive Water / ALFERROCK ® Comparison of heat storage devices Calculation of the amount of heat that can be stored The amount of heat Q that a stored substance can store is determined by the following formula:

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126] 1. Water (for 1 cubic meter)

[0127]

[0128]

[0129]

[0130]

[0131]

[0132] Converted to Wh:

[0133]

[0134] 2. ALFERROCK ® (For 1 cubic meter)

[0135] Converted to Wh:

[0136] 3. Comparison with ALFERROCK ® / water

[0137] ALFERROCK ® It can store 19.7 times the amount of heat at operating temperatures up to 1000℃.

[0138] ALFERROCK ® High-temperature heat storage media can also be excellently used as heat accumulators, heat exchangers, and heat regulators at low temperatures. It is noteworthy that, when the usable material is heated, its density increases from 3.63 g / cm³ at 100°C. 3 Increased to 3.93 g / cm at 1000℃ 3 It is not reversible, but remains constant at 3.93 g / cm³. 3 .parameter This resulted in a 9% increase.

[0139] Table 5 below illustrates the heat storage capacity in the range of approximately 200°C, 300°C, 400°C, 500°C, and 600°C, and shows attractive values.

[0140] Table 5: Requirements for Energy Accumulators

Claims

1. A modified red mud, obtained by heating red mud having the following mineral composition to a temperature of 1000°C: -10-55% by weight of iron compounds, -12-35% by weight aluminum compounds, -3-17% by weight of silicon compounds, -2-12% by weight of titanium dioxide, -0.5-6% by weight of calcium compounds, and - Perhaps there are other unavoidable impurities, Its characteristics are, This modified red mud has a content of 3.90-4.0 g / cm³. 3 Density within the range, wherein the processing technology includes: A mixture of unheated and heated materials at a ratio of 1:1 is used to surface-modify a material using a 5% PDMS (polydimethylsiloxane) prepolymer. This mixture is then fed into a BUSS kneading machine or a parallel twin-screw extruder. The compounding machine has a body temperature of 135°C and maximum vacuum degassing. The torque is adjusted to 65-85% of its maximum value. The material is then removed via a cooling conveyor. The resulting anhydrous and airless product is added to an isolation container and compacted, then slowly heated to 1000°C, thus preparing the accumulator for operation.

2. The modified red mud according to claim 1, wherein, The modified red mud has an average particle size d50 between 3 and 10 micrometers.

3. The modified red mud according to claim 2, wherein, The modified red mud has an average particle size d50 between 5 and 8 micrometers.

4. The modified red mud according to claim 1, wherein, The modified red mud has a particle size d10 between 0.5 and 2.5 micrometers.

5. The modified red mud according to claim 4, wherein, The modified red mud has a particle size d10 between 1.0 and 2.0 micrometers.

6. The modified red mud according to claim 1, wherein, The modified red mud has a particle size d90 between 15 and 50 micrometers.

7. The modified red mud according to claim 6, wherein, The modified red mud has a particle size d90 between 20 and 40 micrometers.

8. The modified red mud according to claim 1, wherein, The modified red mud has a specific heat capacity of 0.6-0.8 kJ / (kg) at 20℃. * Within the range of K).

9. The modified red mud according to claim 8, wherein, The modified red mud has a specific heat capacity of 0.65-0.75 kJ / (kg) at 20℃. * Within the range of K).

10. The modified red mud according to claim 1, wherein, The modified red mud has a specific heat capacity of 0.9-1.3 kJ / (kg) at 726.8℃. * Within the range of K).

11. The modified red mud according to claim 10, wherein, The modified red mud has a specific heat capacity of 0.95-1.2 kJ / (kg) at 726.8℃. * Within the range of K).

12. The modified red mud according to claim 1, wherein, The modified red mud has a specific thermal conductivity of 3-35 W / (m). * Within the range of K).

13. The modified red mud according to claim 12, wherein, The modified red mud has a specific thermal conductivity of 5-20 W / (m). * Within the range of K).

14. The modified red mud according to any one of claims 1 to 13, wherein, The modified red mud exists in the form of pressed solids.

15. The modified red mud according to claim 1, wherein, The modified red mud has a content of 3.93 g / cm³. 3 The density.

16. A method for producing modified red mud according to any one of claims 1 to 15, comprising heating red mud having the following mineral composition to a temperature of 1000°C in an oxygen atmosphere: -10-55% by weight of iron compounds, -12-35% by weight aluminum compounds, -3-17% by weight of silicon compounds, -2-12% by weight of titanium dioxide, -0.5-6% by weight of calcium compounds, and - Perhaps there are other unavoidable impurities.

17. The method for manufacturing modified red mud according to claim 16 further includes pressing the red mud after heating.

18. A storage medium comprising modified red mud according to any one of claims 1 to 15.

19. The storage medium according to claim 18, further comprising one or more of the following components: -A substance used to prevent air entrainment and air adsorption. - Substances used to improve thermal conductivity - Substances used to form thixotropic components.

20. The storage medium according to claim 19, characterized in that, Substances used to improve thermal conductivity are selected from the group consisting of metal colloids, metal powders, graphite, and silicon-containing substances.

21. A heat storage device comprising a storage medium according to any one of claims 18 to 20.

22. The heat storage device according to claim 21 further includes means for charging and discharging the heat storage device.

23. The heat storage device according to claim 21 or 22, wherein the heat storage device is an electric current-heat storage device and further comprises a resistance wire.

24. Use of the modified red mud according to any one of claims 1 to 15 as a storage medium.

25. The use according to claim 24, wherein, The storage medium is the storage medium in the heat accumulator.

26. The use according to claim 24, for storing heat at temperatures up to 1000°C.

27. The use according to claim 26, for storing heat at temperatures greater than 100°C and up to 1000°C.

28. The use according to any one of claims 24 to 27, as a storage medium for repeated heating and cooling.

29. The use according to any one of claims 24 to 27, as a storage medium that can be heated and cooled simultaneously.

30. The use according to any one of claims 24 to 27, as a storage medium in an electric current-thermal accumulator.

31. The use according to claim 30, wherein, The storage medium is heated by electric current and / or cooled when an electric current is generated.

32. The use according to claim 30, for storing current obtained from renewable energy sources.

33. The use according to claim 30, wherein, The current-thermal storage device includes a resistance wire that is heated by an electric current and thus heats the storage medium.

34. The use according to any one of claims 24 to 27, wherein, The heat energy stored in the storage medium is transferred to other substances, thereby cooling the storage medium, wherein the other substances are selected from the group consisting of water, salt solution and heat transfer oil.

35. The use according to any one of claims 24 to 27, wherein, The storage medium and energy release device are provided either as an integrated unit or as separate components.

36. The use according to claim 30, wherein, This current-thermal storage device is used to transfer electrical energy after current-thermal coupling is completed, in the absence of a line system.

37. The use according to claim 30, wherein, This current-thermal storage device generates current after thermal-current coupling.

38. The use according to claim 30, wherein, This current-thermal storage device is used to supply energy to isolated energy-consuming devices.

39. The use according to claim 38, wherein, The isolated energy-consuming device is supplied with heat and electricity.

40. The use according to claim 30, wherein, This current-thermal energy storage device is used to supply energy to machines or mobile devices.

41. The use according to claim 40, wherein, The mobile device is a vehicle.

Images