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    • 专利摘要:
    The present invention relates to a method for thermochemical Energiespei insurance by carrying out endothermic chemical reactions for storing thermal energy in the form of chemical energy in one or more chemi's compounds for later re-release in the form of heat energy using chemical equilibrium reactions under cooling or Erhit tion at least one heat transfer medium, with the characteristic that the chemical balance between boric acid and boron trioxide according to the following reversible cumulative reactions is used for storage and re-release of energy: a) for energy storage, the endothermic dehydration of boric acid to boron trioxide by contact of the boric acid with a first Heat transfer medium is passed through, which transfers heat energy to the boric acid; and b) to re-release the energy, the exothermic back reaction, i. Rehydra tion of boron trioxide with water to boric acid takes place, wherein the released energy is absorbed by a second heat transfer medium.
    公开号:AT518448A1
    申请号:T142/2016
    申请日:2016-03-16
    公开日:2017-10-15
    发明作者:Ing Markus Deutsch Dipl；Ing Thomas Karel Bsc；Werner Andreas；Winter Franz；Ing Christian Jordan Dipl
    申请人:Technische Universität Wien；
    IPC主号:
    专利说明:

    The present invention relates to a process for the thermochemical energy storage by means of carrying out endothermic chemical reactions for the storage of heat energy in the form of chemical energy.
    STATE OF THE ART
    Thermochemical energy storage, i. The storage of thermal energy in the form of chemical energy is a method of energy storage that has been known for decades but has only been studied intensively for a few years, with cyclization of at least one chemical compound between the states of at least one reversible equilibrium reaction. US Pat. No. 4,365,475, for example, discloses the combination of two equilibrium reactions for the purpose of thermochemical energy storage, namely the alternating reversible endothermic formation of the two ammine complexes CaCl 2 .8 NH 3 and ZnCl 2 .NH 3.
    In general, the reactions that are suitable for thermochemical energy storage can be divided into two categories, namely the category of "sorption processes", in which the major valencies of the chemical compounds involved remain unchanged and coordinate bonds are obtained only via minor valencies, as in the reactions to ammine complexes cited above but eg also to hydrates and other solvates, as well as the category of "chemical reactions" with change of the main valences. In both cases, metal salts are predominantly used due to the relatively high number of coordination sites or oxidation states.
    Systems described in the literature from both categories are, for example, BaO / BaO 2 (Fahim et al., Chem. Eng. Journal 27 (1), 21-28 (1983)), CUO / CU20 (Chadda et al., Int. Energy Res., 13, 63 (1989), Pb0 / PbCO3 (Kato et al., Prague, Nucl. Energy 32 (3-4), 563-570 (1998)), MgO / Mg (OH) 2 (Aphane et al Anal. Calorim., 96 (3), 987-992 (2009)), CaO / Ca (OH) 2 (Schaube et al., Thermochim., Acta 538 (0), 9-20 (2012). ), as well as various salt hydrates such as MgS04 / MgSO4.7H20 (Ferchaud et al., JPCS 395 (1), 12069 (2012)), but these are still at a very early stage in their development and are of practical or economic value Application at least largely still years away.
    In addition, in all known systems for thermochemical energy storage, the quality of the heat storage material used decreases with increasing number of cycles, so that this either has to be exchanged or, at times, has to be thoroughly cleaned. On the one hand, such a reduction in quality may result from incomplete implementation, e.g. due to the formation of an unreactive layer on the surface of the heat storage material, and on the other hand due to changes in the mechanical properties of the solid particles, e.g. by abrasion, sintering, etc., resulting in a decrease in heat storage capacity, i. the energy storage density, equate. For example, Ishitobi et al. (J. Chem. Eng. Japan 45 (1), 58-63 (2012)) demonstrated a decrease of 30% for the MgO / Mg (OH) 2 system after 105 cycles.
    In addition, the energy storage density in most known cases anyway rather low, and the corrosiveness of some of the salts used is often a technical equipment problem.
    Against this background, the object of the present invention was the development of a new process for thermochemical energy storage with which the above disadvantages can be eliminated.
    SUMMARY OF THE INVENTION
    This object is achieved in a first aspect by the present invention by providing a method of thermochemical energy storage by performing endothermic chemical reactions for storing thermal energy in the form of chemical energy in one or more chemical compounds for later re-release in the form of thermal energy using chemical equilibrium reactions with cooling or heating of at least one heat transfer medium, with the characteristic that the chemical equilibrium between boric acid (H3BO3) and boron trioxide (B2O3) is used to store and re-release the energy according to the following reversible cumulative reactions:
    a) for energy storage, the endothermic dehydration reaction of boric acid to boron trioxide is carried out by contact of the boric acid with a first heat transfer medium, which transfers thermal energy to the boric acid; and b) to re-release the energy, the exothermic back reaction, i. the rehydration of boron trioxide with water to boric acid takes place, the released energy being taken up by a second heat transfer medium.
    Using the equilibrium between boric acid and boron trioxide, as the later examples prove, significantly higher storage densities can be achieved than with previously known systems. Furthermore, the corrosivity of boric acid is extremely low, so that both the boron trioxide and boric acid can not only be easily stored, but also transported, which offers significant advantages over the compounds of the prior art, since the back and the reverse reaction according to above reaction equation does not necessarily have to be in the same place.
    In order to store heat, the boric acid is brought into contact with a hot heat transfer medium in step a) and preferably heated to a temperature of over 200 ° C., paying particular attention to the temperature control (reaction temperature, heating rate, Holding time) is to lay.
    The dehydration of boric acid to boron trioxide does not occur directly, but via intermediates of cyclic metaboric acid or dioxoboric acid with the empirical formula HBO2.
    HBÜ2 I (cubic) ΗΒΟ2II (monoclinic) and III (orthorhombic)
    This is the result of three modifications, which are formed successively when orthoboric acid is heated slowly as the temperature rises, starting at about 80-100 ° C, the third modification (with an orthorhombic crystal structure) in which the boroxine rings of metaboric acid are linked in three dimensions via oxygen atoms are. Upon prolonged heating or from about 130-140 ° C, the metaboric acid passes into the second modification (monoclinic), in which the boroxine rings are linked only in a chain, and only from about 160 ° C takes metaboric their first (cubic) modification with Boroxinringen isolated from each other, which on further heating, eg to above 500 ° C, with renewed dehydration decomposed to boron trioxide.
    In order to achieve as complete a turnover as possible in the shortest possible time and with the least possible expenditure of energy, optimizations have to be carried out. Thus, it is for example advantageous to heat the boric acid in step a) initially to a temperature between 80 ° C and 130 ° C, then to a temperature between 130 ° C and 200 ° C and finally to a temperature above 200 ° C and for to hold a predetermined period of time at the respective temperature, wherein the residence times can be varied depending on the type and dimensions of the respective reactor. To promote the heat transfer from the heat transfer medium to the boric acid, the process of the present invention is carried out in particularly preferred embodiments in one or more fluidized bed reactors. On the one hand high temperatures above 500 ° C can be avoided in this way, the maximum temperature according to the present invention is preferably not more than 300 ° C. In addition, this ensures that the boron trioxide is obtained in crystalline form, since amorphous material hinders the reaction, i. rehydration, in step b) of the method according to the invention. When using fluidized bed reactors used for fluidizing the fluidized bed gas stream can also serve as a heat transfer medium, for example, a hot exhaust gas stream whose heat content is to be stored by the inventive method in the form of chemical energy, or for rehydration of the boron trioxide to boric acid used water vapor (optionally in admixture with air or with respect to this system inert gas) is also used in each case simultaneously for fluidization of the bed material in the fluidized bed reactor.
    In the above-mentioned preferred embodiments of the invention, the reaction and holding times at the respective temperature can be kept relatively short. Preferably, the respective temperature is kept not longer than 4 hours, more preferably not longer than 2 hours and especially not longer than 1 hour, so that the total duration of step a) of the process according to the invention is not more than 6 hours, preferably not more than 5 hours, in particular not more than 4 hours.
    The first heat transfer medium for heating the boric acid in step a) is, as mentioned, preferably a hot gas, more preferably hot air or hot exhaust gas, in particular from an industrial process to store the heat content of this hot medium in the form of chemical energy. This is especially true if step a) is carried out in a fluidized-bed reactor. However, the present invention is not limited to gaseous media as the first heat transfer medium, and liquid or solid heat carriers can be used as long as they do not interfere with the dehydration reaction of the boric acid and, in particular, do not undergo reaction with boric acid. In addition, a direct contact between the heat transfer medium and the boric acid need not necessarily be produced, so that according to the present invention, for example, a heating coil containing a solid boric acid reaction zone of the reactor can be used with a liquid or gaseous hot heat transfer medium contained therein , Also, a combination of two or more media as the first heat transfer medium, e.g. a hot exhaust gas in direct contact with the boric acid and a
    Heating coil with a liquid or gaseous hot medium for additional heating of the reaction zone of the reactor is possible according to the present invention.
    The boron trioxide obtained in step a) is subsequently stored until there is a demand for the energy stored therein and the boron trioxide is rehydrated in step b) of the process according to the invention. As already indicated above, the term "storage" also includes an intermediate transport of boron trioxide or boric acid to another location, if elsewhere there is an urgent need for the energy stored in the boron trioxide or an oversupply of (industrial) waste heat which is to be stored by the method of the present invention. Due to the above-mentioned advantageous properties of the system H3BO3 / B2O3, both the storage and the transportation of the respective chemical compound are not a significant problem, as long as e.g. the hygroscopic boron trioxide is kept in the absence of moisture.
    In step b) of the process of the present invention, the boron trioxide obtained in step a) is then rehydrated, for which purpose it is to be contacted with water or moisture, the heat previously stored therein being released again and transferred to a second heat transfer medium. This second heat transfer medium is also not particularly limited, so that, for example, the first heat transfer medium used in step a) can be used again from a previous dehydration process, optionally after intermediate (further) humidification of the same (for example in a drying process). In general, however, any other medium can be used in any state of aggregation, as long as the water content therein is sufficient to rehydrate the boron trioxide, preferably completely.
    Also, such a moist medium, e.g. a wet gas or liquid solution having a certain water content, not necessarily to absorb and remove all the released heat. This means that the second heat transfer medium can also comprise two (or more) components, namely (at least) a water or steam-containing reaction component and (at least) an actual heat transfer component, which absorbs the majority of the heat of reaction liberated. For the latter purpose, such a heat transfer component - in contrast to the reaction component - does not need to come into direct contact with the boron trioxide, so that, for example, a cooling coil extending through the reaction zone of the corresponding reactor, liquid or gaseous coolant can be used to obtain the majority of the To remove heat from the reaction zone. Such an embodiment simplifies a discontinuous reaction procedure of step b) of the process according to the invention with intermittent admixing of a water-containing reaction component to boron trioxide initially introduced in a reactor.
    In preferred embodiments, the boron trioxide in step b), of course, directly with liquid water or water vapor, preferably water vapor, as a second heat transfer medium - or as a reaction component thereof - brought into contact. This has the advantage that the resulting hot water or hot steam can be fed directly to numerous applications. Above all, however, the presence of water vapor causes the boric acid obtained in step b) to sublime, which is a particularly preferred embodiment of the present invention. The water vapor sublimation of the boric acid formed in the rehydration ensures on the one hand for substantially complete conversion of the reverse reaction, since the reaction product is removed from the reaction mixture and thereby the system is unbalanced and also continuously "fresh" boron trioxide reaches the surface, thereby is kept at a high level of reactivity. On the other hand, at the same time, the boric acid is purified every single cycle of the process of the present invention, thereby eliminating a major drawback of the prior art processes. In the process of the present invention utilizing the boric acid / boron trioxide system, even after numerous cycles of the process Decrease in the heat storage density, since the solid phase of the boric acid is reformed in each cycle by Resublimation described in more detail below. In addition, the particle size of the solid boric acid-depending on the design of the radiator used for resublimation-can be kept relatively small and moreover very uniform, which promotes substantially complete conversion in step a) of the process according to the invention.
    To increase the amount of boric acid per volume unit of vapor which can be sublimated in step b), according to the present invention, superheated steam having a temperature between 110 ° C. and 150 ° C. is preferably used as the second heat transfer medium (or as the heat transfer component thereof).
    The gaseous boric acid obtained by the sublimation is resublimated in preferred embodiments of the process according to the invention, optionally after previous intermediate storage, in a further step c), the heat of sublimation thus released being transferred to a third heat transfer medium, which is not particularly limited. The same options apply analogously as for the first and second heat transfer medium, i. the third heat transfer medium may consist of several components which are brought into direct and / or indirect contact with the gaseous boric acid and which are e.g. may in turn comprise a cooling coil. In some preferred embodiments, the first heat transfer medium also serves as the third heat transfer medium, which is preheated in step c) before the renewed contact with the solid boric acid in step a). This is particularly preferably a liquid or gaseous heat transfer component of the first and the third and optionally also the second heat transfer medium carried in a cooling coil (in step c)) or heating coil (in step a)).
    Preferably, the gaseous boric acid in step c) is not only resublimated, but - also at the same time as the resublimation step or subsequently - also dried and optionally classified to obtain uniform particle sizes, before being recycled, preferably after intermediate storage, to step a).
    As mentioned above, in particularly preferred embodiments, at least one, preferably both, of steps a) and b) and optionally step c) are carried out in a fluidized bed reactor, in particular all three steps a) to c), wherein several or all of the three Process steps can also be performed in the same fluidized bed reactor, which offers significant advantages especially when the thermochemically to be stored (waste) heat and heat transfer currently staggered incurred in the same place. This eliminates not only the need for transport of the reaction components and process products, but also a complex purification of the reactor. With a suitable reaction procedure of the method according to the invention, in each case complete reaction of the starting materials in the outward and the reverse reaction incurred in the reactor hardly appreciable amounts of impurities, which are due to the reactants. The use of a fluidized bed reactor also causes in Resublimationsschritt c) very small particle sizes of boric acid and in all three steps a thorough mixing of the reactants, substantially complete reaction conversions, good heat transfer and thus short reaction times.
    As special cases of back and forth reactions carried out at the same place, embodiments are to be mentioned in which part of the heat required for the dehydration reaction is provided by technical work or part of the energy released in the back reaction is used to perform work, for example by Forming water vapor is used to drive a turbine or the like. Such embodiments of the method according to the invention by implementing a heat-power process - or its reversal - are expressly also encompassed by the present invention.
    In a second aspect, the present invention provides apparatuses for carrying out preferred embodiments of the method according to the first aspect of the invention by sublimating the rehydrated boric acid, wherein some embodiments of the apparatus comprise: a first reactor having a supply of solid boric acid, a feed line for the first heat transfer medium and a discharge for solid boron trioxide; a second reactor, into which the discharge from the first reactor opens and which further has a supply line for water or steam and a discharge for water vapor and gaseous boric acid; - A downstream of the second reactor cooler for resublimation of gaseous boric acid, which are followed by a dryer, optionally a sieve or classifier, and a return line for the solid boric acid.
    Such an embodiment of the device according to the invention with two reactors, of which at least one of the above reasons is preferably a fluidized bed reactor, makes it possible to achieve the abovementioned advantages of the inventive method by sublimation and resublimation of boric acid. In addition, each of the reaction products, i. the boron trioxide and the boric acid - in solid or gaseous state of aggregation - stored in suitable tanks and, where appropriate, also be transported to a plant of the same type elsewhere to continue there the process of the invention.
    In an alternative embodiment of the second aspect of the invention, an apparatus for carrying out the method according to the first aspect is also provided in a single fluidized bed reactor, which consequently only a fluidized bed reactor and a heatable and / or coolable container for intermediate storage or cooling and connected via lines Resublimation of the gaseous boric acid comprises. Further containers for intermediate storage of the boron trioxide and the solid boric acid may of course also be connected.
    For classifying the solid particles contained in the fluidized bed, the bottom and / or the ceiling or an intermediate ceiling of the single fluidized bed reactor and / or the storage vessel for gaseous boric acid is / are carried out as a sieve, if necessary, for uniform particle sizes of boric acid , boron trioxide and / or bedding material. The opening width of at least one sieve thereof is preferably variably adjustable in order to be able to classify different particle species with different diameters with the same sieve.
    The bed material used in the fluidized bed reactors is limited only insofar as it must be inert to the reactants and a high heat capacity and a high heat transfer coefficient in relation to the
    Fluid bed should have reacted reaction components, including the heat transfer media. The skilled artisan will, without undue experimentation, be able to select a suitable bed material of suitable particle size, e.g. Ceramic particles.
    BRIEF DESCRIPTION OF THE DRAWINGS
    The present invention will be further described by way of non-limitative example with reference to the accompanying drawings, in which:
    Fig. 1 is a schematic representation of the sequence of an embodiment of the method according to the invention or a plant for carrying it out using two separate reactors.
    Fig. 2 is a schematic representation of the sequence of an embodiment of the method according to the invention or a plant for carrying out the same using a single fluidized bed reactor.
    EXAMPLES
    The following examples are merely illustrative of various embodiments of the method according to the invention and should not be construed as limiting the scope of protection.
    Example 1 - Carrying out the process according to the invention in two reactors As shown schematically in FIG. 1, boric acid (obtained from Ridel-de Haen) was initially charged in a reactor 1, more specifically in a thermally isolated fluidized bed reactor, as is preferred according to the present invention and at the same time served as bedding material. In the laboratory experiment described herein, air which had been preheated to the respective temperature was then introduced into the fluidized-bed reactor 1 via feed line 3 and simultaneously served as the fluidizing medium and the first heat transfer medium for heating the boric acid. In commercial practice, instead, for example, a hot industrial waste gas or the like via line 3 a the reactor 1 on and discharged via line 12 again from this, which is optionally subjected to appropriate pre-cleaning steps.
    Due to the strong influence of particle size in fluidized bed reactors, this was adjusted by means of a Vibro Siebturms 10 (available from Retsch GmbH) to a range of 200 to 630 gm before the boric acid via line 2 (again) was introduced into the reactor 1. In this way, a bed expansion of at least 150% was ensured.
    The air flow supplied via line 3 at a rate of 16 l / min was regulated according to the following three-stage temperature scheme:
    Stage 1: 100-120 ° C for 60 min Stage 2: 170-185 ° C for 60 min Stage 3: 215-225 ° C for 60 min
    Instead of or in addition to the preheated air flow, especially in conventional, i. not operated as a fluidized bed - reactors are heated by means of heating jackets, snakes or the like, as indicated in Fig. 1 by reference numeral 11.
    Subsequently, the boron trioxide obtained was cooled to room temperature, transferred via a discharge 4a into a storage container 13 and determined by means of a sample its particle size, which was for the majority of the particles between 250 and 450 pm.
    The boron trioxide thus obtained was transferred via line 4b to a fluidized bed reactor 5, in which quartz sand was used as additional bed material, since the boric acid formed from the boron oxide during rehydration passes into the gas phase by sublimation. As fluidization and second heat transfer medium (or a reaction component thereof) was fed via a supply line 6 either hot humid air or superheated steam having a temperature between 105 ° C and 150 ° C and variable flow rates between 3 and 8 l / min, and also the residence times of the reactants were varied between 5 and 30 minutes. As currently preferred variant of the process procedure, a combination of saturated humid air at 85 ° C. with a feed rate of 4 l / min has proven to be effective with regard to the reaction procedure.
    The resulting gaseous mixture of boric acid and water vapor (and optionally air) was transferred via a line 7 in a cooling tower 8, was used in the coolant as water at a constant temperature of about 15 ° C, as shown in Fig. 1 with reference numeral 8a is hinted at. Alternatively, a cooling unit may also be provided at the top of the fluidized-bed reactor 5, in the region of which the gas mixture can be conveyed by corresponding intensification of the fluidization, in which case conduit 7 can be dispensed with.
    In the process described above, the superheated steam is mainly used as a reaction component, since the energy released in the reaction of boron oxide to boric acid is largely consumed as Sublimationsenthalpie and there is only a slight increase in temperature of the excess of superheated steam, the so-called "carrier gas" for the sublimed boric acid. The energy stored in the boron trioxide in step a) would thus, in industrial application of this embodiment of the method, for the most part be transferred to the coolant 8a serving as the third heat transfer medium in the cooling unit 8 and could be used, for example, as district heating for heating purposes or also under the application of heat and power. Used principle for vaporizing the coolant to drive a gas turbine or the like.
    The new formation of the solid phase of boric acid in the cooling step, there is no contamination of the boric acid, so that even after numerous repetitions of the reaction cycle hardly any material losses are to be lamented.
    The boric acid resublimbed in the condenser 8 is subsequently dried in a conventional manner in a dryer 9 in preferred embodiments of the invention in a dryer 9, although this step is suitably carried out in industrial practice with suitable reaction control, i.e., in a conventional manner. at relatively low water content, may also be omitted if e.g. the first heat transfer medium used is a large amount of hot exhaust gas. The
    Drying could in such cases occur simultaneously with the dehydration in step a) of the process.
    In the case shown in FIG. 1, drying is followed by the already mentioned classification of the boric acid particles in sieve tower 10 in order to ensure a uniform size distribution in reactor 1, which is of great importance especially in the case of continuous reaction control. Those sieve fractions having the desired size distribution are then recycled via line 2 to the first process step a).
    According to calculations by the inventors, energy densities of more than 1 GJ / m3 could already be achieved when carrying out the above embodiment of the method according to the invention for thermochemical energy storage on a laboratory scale. When optimizing the process management, significantly higher values should still be possible, which represents a considerable increase over alternative methods according to the prior art. For example, in energy storage in hot water (with a temperature difference of 60 ° C) only energy densities of 0.25 GJ / m3 and even with thermochemical energy storage by sorption using zeolites only about 0.6 GJ / m3 can be achieved.
    Example 2 - Carrying out the process according to the invention in a reactor As an alternative to the above process procedure in two separate reactors, the process of the present invention can also be carried out in a single reactor, as shown schematically in FIG.
    In preferred embodiments of this variant, both the forward and the reverse reaction take place in a single fluidized bed reactor 20 in which, for example, quartz sand is again present as bed material, which in this case is present in both reactions and should therefore have a particularly high heat capacity. The reactor is preferably equipped with an (additional) heating or cooling element 20a in order to be able to precisely control the temperature of the fluidized bed.
    In the first step a) of this embodiment of the method according to the invention, in turn, the dehydration of boric acid, preferably using a hot industrial waste gas introduced via line 24, two- or three-way valve 26 and line 27 into the reactor 20, after the transfer of heat energy to the boric acid Line 28 is discharged again. The boron oxide formed thereby remains in the reactor in contrast to the embodiment of Example 1, where it can either be immediately rehydrated to boric acid or stored therein.
    Meanwhile, if the boron oxide is stored in reactor 20, it may sometimes be kept at a certain temperature via heating element 20a, which requires good thermal insulation of the reactor, or the heat energy contained in the hot boron oxide may be absorbed by the element 20a serving for cooling in this case be removed and used, which depends inter alia on how long the boron oxide is to be stored until later rehydration.
    By introducing water or steam via line 25, the reverse reaction to boric acid is started at any later time. If liquid water is used as the reaction component, then additionally a carrier gas must be introduced to fluidize the fluidized bed. In this case, the water can either be evaporated by means of heating element 20a, or it is introduced a sufficiently hot fluidizing gas, which may for example also be the hot exhaust gas from line 24, which now serves to heat and evaporate the water and at the same time supports the sublimation of the boric acid formed again ,
    Since in the latter procedure, the boric acid is very diluted, this is not preferred. According to the present invention, in Example 2 (as previously in Example 1) already superheated steam via line 25, valve 26 and line 27 is introduced into the reactor 20, which thus also serves as a fluidizing gas. The steam will be generated for this purpose in a line 25 upstream (not shown) container, preferably using the hot exhaust gas as a heat source.
    The consisting of boric acid and water vapor gas mixture is now forwarded via line 21 in a means 23 a heated or cooled, preferably thermally insulated tank 23. As an alternative to the storage of boron oxide described above, in this tank 23, the water vapor-boric acid mixture can be stored in the gaseous state, in which case container 23 is preferably heated via element 23a, e.g. using hot exhaust gas.
    If storage of the boron oxide has already taken place beforehand, vessel 23 preferably serves as a cooler, in which the gas mixture is cooled by means of element 23a and the boric acid is resubbed and thereby returned to the solid state. In this case, in preferred embodiments, the bottom of the container 23 can be designed as a sieve bottom, preferably switchable, in order to be able to carry out a classification of the newly formed, solid boric acid phase.
    However, if the boric acid is temporarily stored in the gaseous state in the heatable container 23, it can also be recycled in the gaseous state together with the steam via line 22 to the reactor 20, where it is cooled and resublimated, e.g. by a coolant which is guided in the element 20a, which now serves as a cooler, as the third heat transfer medium according to the present invention. In this case, the bottom of reactor 20 may be designed as a sieve bottom.
    As in the embodiment of the process according to the invention described in Example 1, most of the energy stored in the boric acid / boron trioxide system is recovered in the course of resublimation to form a new solid boric acid phase, and of course preferably when no hot exhaust gas (or other) is present Heat source) is available in excess, with the otherwise any heating needs can be met.
    The present invention is of course not limited to the two embodiments shown in the drawings and can be adapted and expanded in individual cases depending on the particular circumstances, e.g. additional revertible reactions of boric acid or boric oxide, as long as they are compatible with the cycle described above and provide additional energy storage or utilization options. The relevant expert is easily able to make necessary adjustments for these purposes of the corresponding system (eg the addition of other required or advantageous reaction or storage containers, lines, valves, heat exchangers for heating and / or cooling, etc.), as well as he is able to select suitable materials for the individual containers and lines (eg stainless steel, quartz glass, etc.).
    As already mentioned, the use of some of the energy for performing work (heat-power coupling) and the interim transport of boron oxide or boric acid are also specifically included in the present invention.
    The latter therefore makes a significant contribution in the field of thermochemical energy storage and advantageously extends the state of the art.
    权利要求:
    Claims (17)
    [1]
    1. A method for thermochemical energy storage by performing endothermic chemical reactions for storing thermal energy in the form of chemical energy in one or more chemical compounds for later re-release in the form of thermal energy using chemical equilibrium reactions under cooling or heating at least one heat transfer medium, characterized in that the chemical equilibrium between boric acid and boron trioxide is used to store and re-release the energy according to the following reversible cumulative reactions:

    wherein a) for energy storage, the endothermic dehydration reaction of boric acid to boron trioxide is carried out by contact of the boric acid with a first heat transfer medium, which transfers heat energy to the boric acid; and b) to re-release the energy, the exothermic back reaction, i. the rehydration of boron trioxide with water to boric acid takes place, the released energy being taken up by a second heat transfer medium.
    [2]
    2. The method according to claim 1, characterized in that the boric acid is heated in step a) to a temperature of about 200 ° C.
    [3]
    3. The method according to claim 2, characterized in that the boric acid in step a) initially to a temperature between 80 ° C and 130 ° C, then to a temperature between 130 ° C and 200 ° C and finally to a temperature above 200 ° C is heated and held for a predetermined period of time at the respective temperature.
    [4]
    4. The method according to any one of claims 1 to 3, characterized in that the heating of the boric acid in step a) takes place by means of hot air or hot exhaust gas as the first heat transfer medium.
    [5]
    5. The method according to any one of claims 1 to 4, characterized in that the boron trioxide is brought in step b) with liquid water or water vapor, preferably water vapor, as the second heat transfer medium in contact.
    [6]
    6. The method according to claim 5, characterized in that the boron trioxide in step b) brought into contact with water vapor and the boric acid formed thereby is sublimated.
    [7]
    7. The method according to claim 6, characterized in that superheated steam having a temperature between 110 ° C and 150 ° C is used.
    [8]
    8. The method according to claim 6 or 7, characterized in that the gaseous boric acid resublimated in a further step c) and the thereby released Sublimationswärme is transferred to a third heat transfer medium.
    [9]
    9. The method according to claim 8, characterized in that in step c) the gaseous boric acid resublimiert, dried, optionally classified, and recycled to step a).
    [10]
    10. The method according to any one of claims 1 to 9, characterized in that at least one, preferably both, the steps a) and b) and optionally step c) is carried out in a fluidized bed reactor / are.
    [11]
    11. The method according to claim 10, characterized in that the gas stream used for fluidizing the fluidized bed also serves as a heat transfer medium.
    [12]
    12. The method according to claim 10 or 11, characterized in that several or all process steps are carried out in the same fluidized bed reactor.
    [13]
    13. A device for carrying out a method according to one of claims 6 to 1, comprising: - a first reactor (1) with a supply line (2) for solid boric acid, a supply line (3) for the first heat transfer medium and a discharge (4) for solid boron trioxide; - A second reactor (5) into which the discharge (4) from the first reactor (1) opens and which further comprises a supply line (6) for water or steam and a discharge (7) for water vapor and gaseous boric acid; - A downstream of the second reactor (5) cooler (8) for resublimation of the gaseous boric acid, which are followed by a dryer (9), optionally a sieve or sifter (10), and a return line (2) for the solid boric acid.
    [14]
    14. The device according to claim 13, characterized in that the first and / or the second reactor (1.5) is a fluidized bed reactor / are.
    [15]
    15. An apparatus for carrying out a method according to claim 12, comprising a single fluidized bed reactor (20) and via lines (21, 22) connected thereto heatable and / or coolable container (23) for temporary storage or cooling and resublimation of the gaseous boric acid.
    [16]
    16. The apparatus according to claim 15, characterized in that for classifying the solid particles contained in the fluidized bed of the bottom and / or the ceiling or a false ceiling of the fluidized bed reactor (20) and / or the storage container (23) as, optionally switchable, sieve is executed / are.
    [17]
    17. The apparatus according to claim 16, characterized in that the opening width of at least one sieve is variably adjustable.
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    同族专利:
    公开号 | 公开日
    WO2017156564A2|2017-09-21|
    WO2017156564A3|2017-12-28|
    AT518448B1|2017-12-15|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    EP0824502A1|1995-05-01|1998-02-25|U.S. Borax Inc.|Production of boric oxide|
    EP1975219A2|2007-03-28|2008-10-01|Robert Bosch GmbH|Thermochemical heat reservoir and heating system with a thermochemical heat reservoir|
    US20100263832A1|2009-04-16|2010-10-21|Dalla Betta Ralph A|Thermochemical Energy Storage System|
    AT5910B|1900-01-13|1901-11-25|Rappold & Steiger|
    FR1603222A|1968-10-17|1971-03-22|
    ITMI981138A1|1998-05-21|1999-11-21|Getters Spa|PROCESS FOR THE REMOVAL OF WATER FROM EVACUATED ROOMS OR GAS|
    JP2017002163A|2015-06-09|2017-01-05|パナソニック株式会社|Heat storage material, heat storage device and heat storage method|CN112473586A|2020-11-30|2021-03-12|上海交通大学|Thermochemical heat storage reactor|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA142/2016A|AT518448B1|2016-03-16|2016-03-16|Process for thermochemical energy storage|ATA142/2016A| AT518448B1|2016-03-16|2016-03-16|Process for thermochemical energy storage|
    PCT/AT2017/060066| WO2017156564A2|2016-03-16|2017-03-15|Method for thermochemical energy storage|
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