Technical field

[001] The present invention relates to a fluidized bed reactor for continuous generation of thermochemical heat energy. According to a preferred embodiment, by utilizing solid particles from reaction calcium oxide + steam -> calcium hydroxide (Ca(OH)2).

[002] The present invention relates to corresponding method for continuous generation of thermochemical heat energy, advantageously, from reaction calcium oxide (CaO) + water (H2O) in gas phase (steam) -> calcium hydroxide (Ca(OH) ₂ ).

[003] The present invention relates also to corresponding system for storing and releasing heat energy based on the reaction and its reverse reaction.

Background art

[004] Fossil fuels have been a convenient and widely available source of energy but due to environmental aspects interest towards alternative fuels and energy production has been increased. Therefore, fuels with low-carbon energy carriers, with high energy density, have been found to be an alternative to replace the multiple indispensable roles of fossil fuels, including for electrical and thermal power generation, for powering transportation fleets, and for global energy trade. A reversible exothermic reaction such as CaO with water is considered one of the most promising reactions for high temperature thermal energy storage. Metal fuels, as recyclable carriers of clean energy, are promising alternatives to fossilfuels in a future low carbon economy. Metals have high energy densities and metals are, therefore, fuels within many batteries, energetic materials, and propellants. Metal fuels can be burned with air or reacted with water to release their chemical energy at a range of power generation scales. The metal-oxide combustion products are solids that can be captured and then be recycled using zero- carbon electrolysis processes powered by clean energy, enabling metals to be used as recyclable zero-carbon solar fuels or electro fuels. A key technological barrier to the increased use of metal fuel is the current lack of clean and efficient combustor/reactor/engine technologies to convert the chemical energy in metal fuels in to motive or electrical power (energy).

[005] WO 2021/105467 discloses a system for energy storage comprising a fluidized bed apparatus with an energy storage material. The energy storage material comprises at least one selected from CaO, Ca(OH)2, CaCO3, MgO, Mg(OH)2, MgCO3, BaO, Ba(OH)2, BaCO3, and metal hydrides such as MgH2. In one embodiment, the fluidized bed apparatus comprises at least one perforated separator, the perforated separator creates more than one fluidization compartments in the fluidized bed apparatus. This creates a plurality of fluidization zones in the fluidized bed apparatus. Such a setup provides the possibility of having different conditions in the different zones. The perforated separator is at least partially foraminous. A perforated separator is in one embodiment arranged horizontally so that an upper and a lower fluidization zone are created. In another embodiment several perforated separators are arranged to create a plurality of fluidization zones. A perforated separator has the advantage of creating several fluidization zones where the conditions can be held differently. For instance, the temperature can be different. The process can be made more efficient if for instance a first preheating is followed by a second heating to a higher temperature. The devices for introduction of pressurized fluid are not shown in the publication.

[006] An object of the invention is to provide an improved fluidized bed reactor for generation of thermochemical heat energy in which the performance is considerably improved compared to the prior art solutions, the performance is especially improved in terms of reliable operation, runnability, yield and efficiency during use of the reactor. Also it is an object of the invention to achieve an industry scale reactor where the reaction can occur in a uniform manner. It is an object of the invention to provide an improved fluidized bed reactor for solid particles of alkaline earth metals or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn). Disclosure of the Invention

[007] Objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.

[008] According to an embodiment it is provided a fluidized bed reactor for continuous generation of thermochemical heat energy by utilizing one of reaction:

1) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn), in elemental form + an oxidizer in gaseous or vapor form such as steam or oxygen-containing gas or vapor, or

2) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn), in oxidized form + a hydrating compound in gaseous or vapor form in order to obtain hydroxide, the reactor comprising:

- a reactor chamber,

- an inlet arranged to the first end of the reactor chamber for feeding the solid particles into the reactor,

- inside the reactor chamber it is arranged an array of fluidizing stages, wherein each one of the fluidizing stages comprises a number of nozzles for fluidizing the solid particles with a reactive fluidizer, the oxidizer or the hydrating compound, to initiate and proceed with the reaction,

- fluidizing stages are provided with one or more heat exchangers for selectively recovering the heat released from the reaction,

- an outlet is arranged at the opposite end to the first end of the reactor chamber for exit of reaction material.

[009] According to an embodiment it is provided a method for continuous generation of thermochemical heat energy by utilizing one of reaction:

1) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn) in elemental form + an oxidizer in gaseous or vapor form such as steam or oxygen-containing gas or vapor, or 2) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn), in oxidized form + a hydrating compound in gaseous or vapor form in order to obtain hydroxide, the method comprises following steps:

- feeding a feedstock of solid particles to a reactor chamber at a first end of the reactor chamber,

- fluidizing the solid particles with fluidizing jets of a first fluidizing stage to initiate the reaction,

- generated heat is transferred to heat exchangers in the reaction chamber,

- continuing the feeding of feedstock from the first end of the reactor chamber forces the feedstock / partly reacted material -mixture to move to the consequent fluidizing stage where fluidizing of mixture with fluidizing jets continues and the released heat is being transferred by the heat exchangers at that fluidizing stage, as the fluidizing continues, the mixture composition turns in to more end material and after the last fluidizing stage the mixture contains only minor proportion of the feedstock, yield of the reaction is controlled with the fluidizing stream temperature, saturation and flow velocity in each of the fluidizing stage,

- the reaction material is removed from the reaction chamber via outlet.

[0010] For the clarification purposes only the terminology reaction material refers to the end material i.e. reaction product that will be removed from the reaction chamber via outlet. For example, in case of reaction being calcium oxide (CaO) + water (H2O) in gas phase i.e. steam, the reaction material is calcium hydroxide (Ca(OH) ₂ ).

[0011] According to an embodiment, when one of disclosed metals is used as solid particles to be introduced into the reactor chamber and when fluidization agent is oxygen-containing gas, combustible conditions occur in the reactor chamber. Generally, utilizing metal powder with staged fluidization reactor chamber will form combustible circumstances as metal will oxidize.

[0012] As the above disclosed general reaction, reactor and method are suitable for several solid particle or powderous materials, the invention is here explained in more detail in connection with one of the preferred embodiments, the reaction being calcium oxide (CaO) + water (H2O) in gas phase i.e. steam -> calcium hydroxide (Ca(OH)2), because it is one of the most economically viable alternatives for this purpose. Another preferred embodiment is with magnesium: MgO + H2O — > Mg(OH)2, the other disclosed materials: lithium (Li), boron (B), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn) may be used as well. In the following disclosure, even if the process is disclosed as using the reaction of CaO I Ca(OH)2, the method and the reactor is directly applicable also to the other disclosed materials: alkaline earth metals or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn).

[0013] According to an embodiment, the solid particle size may be in the range of 1-1000 pm or 1-500 pm, or 100-300 pm. The solid particle size has an effect on both the reaction itself and on the fluidizability of the particles, the smaller the particle size, the faster is the reactivity and fluidizability. To gain a wanted controllability, the particle size may selected as needed and practical operational conditions.

[0014] According to an embodiment of the invention, non-reactive fluidizer may be introduced to the reactor in addition of introducing a reactive fluidizer, the oxidizer or hydrating compound. Non-reactive fluidizer means in this case that it will not participate in the reaction. Advantageously, non-reactive fluidizer may improve distribution of particles and so promote reaction while not chemically participating it. According to an embodiment of the invention, in case of calcium oxide (CaO) + water (H2O) in gas phase (steam) -> calcium hydroxide (Ca(OH)2) wherein steam is a reactive fluidizer, air and/or oxygen-containing gas as non- reactive fluidizer may be introduced into a reactor chamber. According to an embodiment of the invention, non-reactive fluidizer may be introduced at same vertical levels as the reactive fluidizer. According to an embodiment of the invention, the reactor is provided with nozzles for introducing a mixture of reactive fluidizer and non-reactive fluidizer into the reactor chamber, either via same nozzles or the reactor is provided with separate nozzles for reactive fluidizer and non-reac- tive fluidizer. Thus, a mixture of reactive fluidizer and non-reactive fluidizer are introduced into the chamber via nozzles, either via same nozzles as the reactive fluidizer or the reactor is provided with separate nozzles for reactive fluidizer and non-reactive fluidizer. Here a nozzle means a device that produces substantially one directional flow over the nozzle. Thus, each of the fluidizing nozzles being arranged in fluid communication with a source of reactive fluidizer so that reactive fluidizer will be introduced through nozzles, preferably, independently at each levels. According to an embodiment of the invention, especially in a case of one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), and zinc (Zn) solid particles, a non-reactive fluidizer, such as inert gas, may be introduced into the reactor chamber.

[0015] According to an embodiment, when CaO is introduced and fluidization agent is steam, calcium hydroxide is formed and no combustion takes place.

[0016] According to an embodiment of the invention it is provided a fluidized bed reactor for continuous generation of thermochemical heat energy by utilizing solid particles from reaction calcium oxide (CaO) + water (H2O) in gas phase (steam) -> calcium hydroxide (Ca(OH)2), the reactor comprising:

- a reactor chamber,

- an inlet arranged to the first end of the reactor chamber for feeding solid particles of CaO into the reactor,

- inside the reactor chamber it is arranged an array of fluidizing stages, wherein each one of the fluidizing stages comprises a number of steam nozzles for fluidizing CaO with steam to initiate and proceed with the reaction,

- fluidizing stages are provided with one or more heat exchangers for selectively recovering the heat released from the solid material in the reaction,

- an outlet is arranged at the opposite end to the first end of the reactor chamber (10) for exit of Ca(OH)2.

[0017] According to an embodiment of the invention, a method for continuous generation of thermochemical heat energy from reaction calcium oxide (CaO) +water (H2O) in gas phase (steam) -> calcium hydroxide (Ca(OH)2), the method comprises following steps:

- feeding solid particles of CaO to a reactor chamber at a first end of the reactor chamber,

- fluidizing CaO with steam jets of a first fluidizing stage to initiate the reaction, - generated heat is transferred to heat exchangers in the reaction chamber,

- continuing the feeding of feedstock of CaO from the first end of the reactor chamber forces the partly reacted CaO I Ca(OH)2 -mixture to move to the consequent fluidizing stage where fluidizing of mixture with steam jets continues and the released heat is being transferred by the heat exchangers at that fluidizing stage, as the fluidizing continues, the CaO I Ca(OH)2 -mixture composition turns in to more Ca(OH)2 and after the last fluidizing stage the mixture contains Ca(OH)2 with only minor proportion of CaO, yield of the reaction is controlled with the steam temperature, saturation and flow velocity in each of the fluidizing stage,

- the reaction product Ca(OH)2 is removed from the reaction chamber via outlet.

[0018] This provides an effect by means of which the thermochemical heat energy has been efficiently released from the feedstock and the reaction product is still in a dry particle or powderous form so that it is easy to store and it is relatively simple to regenerate in a reverse reaction back to the initial material, to alkaline earth metal or metal in elemental form or to alkaline earth metal or metal in oxidized form, such as Ca(OH)2 -> CaO. Thus, the performance of the reactor, method and system for continuous generation of thermochemical heat energy is considerably improved. The invention ensures proper fluidization velocities and dispersion of solid particles inside reactor from bottom to top. The reaction of the temperature is a function of the steam partial pressure, below an equilibrium curve: e.g. at 100kPa (1bar) the equilibrium temperature is around 520C and if temperature is over 520C reaction turns into dehydration. One advantage of the present reactor is that heat recovery with heat exchangers is improved because the reaction can take place uniformly in the reactor.

[0019] According to the embodiment inside the reactor chamber it is arranged an array of fluidizing stages, wherein each one of the fluidizing stages comprises a number of steam nozzles for fluidizing CaO with steam to initiate and proceed with the reaction. It has been noted that an efficient thermochemical process is better to be conducted in several stages to have maximum efficiency and yield. However, the properties of calcium oxide and later mixture of calcium oxide / calcium hydroxide change during the process I reaction in such a way that the fluidizing properties are different. Thus, continuing the feeding of feedstock of CaO from the first end of the reactor chamber forces the partly reacted CaO I Ca(OH)2 -mixture to move to the consequent fluidizing stage where fluidizing of mixture with steam jets continues and the released heat is being transferred by the heat exchangers at that fluidizing stage, as the fluidizing continues, the CaO I Ca(OH)2 -mixture composition turns in to more Ca(OH)2 and after the last fluidizing stage the mixture contains Ca(OH)2 with only minor proportion of CaO. According to an embodiment the fluidizing stages are configured within one compartment to enable efficient flow and reaction of CaO I Ca(OH)2 in the reactor chamber. In the prior art document WO 2021/105467 there is disclosed that the reaction is conducted in several compartments separated by foraminous or perforated separators divided in vertical direction. In theory the compartments may also be arranged in the horizontal direction. However, in the prior art document the examples are presented in a laboratory scale, the reactor volume is about 600 ml. As the present invention is intended for industry size operations and a power capacity of megawatts, the reactor volume would be counted from cubic meters to hundreds of cubic meters, the present inventor has discovered that there may be a potential clogging problem in the separators and it would be better to streamline the reactor in such a way that no separators or compartments would be needed. This has considerable effect on runnability and operation of the reactor in continuous use since the clogging would require shutdown of the reactor and cooling it down for days until the clogged material would have been removed.

[0020] According to embodiments of the invention, the reactor chamber is free from division walls and/or compartments and/or perforated separators between fluidization stages. The effect of the feature that inside the reactor chamber it is arranged an array of fluidizing stages, wherein each one of the fluidizing stages comprises a number of nozzles for fluidizing solid particles with reactive fluidizer to initiate and proceed with the reaction, the reactor may be designed to be free from compartments divided by perforated plates and/or division walls between the fluidization stages. It is thus possible to utilize advantageously the whole reactor chamber for promoting thermochemical reaction and recovering heat. It also prevents possible clogging problems or other accumulation of the material, meaning the feedstock, partially reacted material or the end product, in other words the reaction material.

[0021] According to an embodiment of the invention, one array of fluidization stage is arranged at a bottom portion of the reactor chamber so as to form a first fluidization stage and other arrays of fluidization stages are arranged at a vertical level higher than the first fluidization stage. Advantageously, different arrays of fluidization stages can be arranged at different vertical levels. It is possible to utilize stages at different levels in a reactor chamber arranged vertically or in an inclined configuration of the reactor chamber. Advantageously, different fluidization stages or different fluidizations levels may provide the following synergy and/or advantages: distribution of particles will be improved with fluidization while utilizing the fluidization agent as media for participating in reaction and forming end material, from the feedstock and fluidization agent, at the same time. Fluidization agent may be ‘consumed’ and/or ‘captured’ in the reaction of forming end material. It should be noted that feedstock material (e.g. CaO) may have of different density than the formed end product (e.g. Ca(OH)2). Furthermore, the fluidizing agent (e.g. steam) may have different density than the feedstock and/or end product.

[0022] According to an embodiment the reactor is circular in cross section and has its length greater than the width or diameter. The fluidization and the following reaction can be done in an efficient manner and the length enables that the reactor may comprise two to five fluidizing stages in the reactor chamber, preferably 3 to 4 fluidizing stages. Further this enables the process efficiency to be adapted to the optimum, about all the input material is reacted to calcium hydroxide and no by-pass or spillover calcium oxide is flown to the outlet of the reactor.

[0023] According to an embodiment the reactor is vertical having the inlet and outlet configured on vertical position relating to each other in the reactor chamber. Preferably, in a vertical reactor configuration, a vertical height of the reactor is greater than a horizontal width of the reactor. With this vertical configuration it is possible to control the material flow and simultaneous reaction so that the control parameters are input feed (mass flow), fluidizing steam velocity at nozzles of each stage, steam temperature and saturation (water content). Still according to an embodiment the steam temperature may be increased gradually, decreased gradually or stay the same from fluidizing stage to consequent fluidizing stage. According to an embodiment the steam velocity at steam nozzle may decrease or increase gradually from fluidizing stage to consequent fluidizing stage. Nozzle sizes and/or shapes may vary in the fluidizing stage and/or fluidizing stages so as to provide advantageous fluidization and reaction. Still according to an embodiment the reactor is provided with a gas exit channel for exit of excess fluid- izer.

[0024] According to an embodiment it is provided a system for storing and releasing heat energy based on reaction CaO + H2O -> Ca(OH)2 and Ca(OH)2 + heat -> CaO + H2O, the system comprises the reactor as explained above for utilizing method disclosed above, and wherein the system further comprises a storage for CaO and a storage for Ca(OH)2, and a regeneration reactor for a process of returning Ca(OH)2 back to CaO, the system is utilized in releasing heat when needed and storing heat when available.

[0025] The heat generated in the above explained reaction, e.g. CaO + H2O -> Ca(OH)2, and recovered by the heat exchangers may be utilized for example in district heating and/or for generating electricity. The fluidizing stages are provided with one or more heat exchangers for selectively recovering the heat released from the reaction. This term “selectively recovering” means here that the heat exchangers may be different to each other in actual design or operating conditions, to achieve the most efficient heat recovery for each of the locations within the reactor chamber. Preferably part of the generated heat is utilized in maintaining the reaction, to heat the fluidizing agent, such as steam. Also, the steam introduced into the reactor chamber may be extracted from a main steam line of the reactor. There are several possible ways to arrange the heat exchangers. For example, an arrangement of different heat exchangers ordering could be the following: superheater, evaporator, economizer, as the first heat exchanger in the reactor chamber would most likely to be the hottest one. The aim is in all of the embodiments that the temperature of the reaction material at the outlet is as low as possible so that all the heat generated in the reaction has been transferred to the heat exchangers.

[0026] Advantageously, due to the fluidization stages, the reaction at the inlet side of the reactor chamber may be promoted, as well as distribution of particles with fluidization. Advantageously, fluidization and/or particle velocity may be maintained at desirable level and/or uniform which may prevent potential erosion issues, for instance if the fluidization would be conducted only at the bottom of the reactor chamber. Nozzle sizes and/or shapes may vary in the fluidizing stage and/or fluidizing stages so as to provide advantageous fluidization and reaction. By the staged fluidization, the reactor volume may be advantageously optimized to achieve high intensity in energy releasing.

[0027] The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims.

Brief Description of Drawings

[0028] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in which

Figure 1 illustrates a reactor according to an embodiment of the invention,

Figure 2a and 2b illustrates cross sectional nozzle configurations according to embodiments of the invention,

Figure 3 illustrates a reactor according to still another embodiment of the invention,

Figure 4 illustrates a system according to an embodiment of the invention,

Figure 5 illustrates a reactor according to an embodiment of the invention.

Detailed Description of Drawings [0029] Figure 1 depicts schematically a fluidized bed reactor 1 for continuous generation of thermochemical heat energy by utilizing one of reaction:

1) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in elemental form + an oxidizer in gaseous or vapor form such as steam, air or oxygen, or

2) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in oxidized form + a hydrating compound in gaseous or vapor form in order to obtain hydroxide, the reactor 1 comprising:

- a reactor chamber 10,

- an inlet 2 arranged to the first end of the reactor chamber 10 for feeding the solid particles into the reactor 1 ,

- inside the reactor chamber 10 it is arranged an array of fluidizing stages 3, wherein each one of the fluidizing stages 3 comprises a number of nozzles 32 for fluidizing the solid particles with a reactive fluidizer, the oxidizer or the hydrating compound, to initiate and proceed with the reaction,

- fluidizing stages 3 are provided with one or more heat exchangers 4 for selectively recovering the heat released from the reaction,

- an outlet 5 is arranged at the opposite end to the first end of the reactor chamber 10 for exit of reaction material.

[0030] In other words, the reactive fluidizer is introduced through the nozzles 32 of each of the fluidizing stages 3 so as to fluidizing solid particles with the reactive fluidizer. It is illustrated a number of nozzles for feeding a reactive fluidized for fluidizing solid particles. Thus, it renders possible to introduce the reactive fluidizer through nozzles at different levels in Fig. 1 at different vertical levels. In addition to feeding reactive fluidizer, it may be possible to feed also non-reac- tive fluidizer from the same nozzles or a mixture of reactive and non-reactive fluidizer from the same nozzles. Thus, fluidization as well as reaction at each fluidization stage 3 may be advantageously controlled. [0031] According to a preferred embodiment, the Fig 1 depicts schematically a fluidized bed reactor 1 for continuous generation of thermochemical heat energy by utilizing solid particles from reaction calcium oxide (CaO) + water (H2O) in gas phase (steam) -> calcium hydroxide (Ca(OH)2), the reactor 1 comprising:

- a reactor chamber 10,

- an inlet 2 arranged to the first end of the reactor chamber 10 for feeding the solid particles of CaO into the reactor 1 ,

- inside the reactor chamber 10 it is arranged an array of fluidizing stages 3, wherein each one of the fluidizing stages 3 comprises a number of steam nozzles 32 for fluidizing CaO with steam to initiate and proceed with the reaction,

- fluidizing stages 3 are provided with one or more heat exchangers 4 for selectively recovering the heat released from the solid material in the reaction,

- an outlet 5 is arranged at the opposite end to the first end of the reactor chamber 10 for exit of Ca(OH)2. In addition to the reactor 1 itself, it is presented in the Fig. 1 an embodiment where the feedstock material CaO is stored to a storage 6 and from there is it fed to the reactor 1 by suitable means such as a screw conveyor (not shown, nor are valves and other instrumentation shown in in Fig. 1). After the reactor 1 the reaction material or end material, is led to a storage 7. The reactor 1 is vertical having the inlet 2 and outlet 5 configured on vertical position relating to each other in the reactor chamber 10. According to an embodiment shown in in Fig. 1 , the inlet 2 for introducing solid particulate material is arranged at a top portion of the reactor chamber 10 and outlet 5 for discharging reacted material is arranged at a bottom portion of the reactor chamber 10 so being opposite end of the inlet 2. In Fig. 1 there are presented an array of five fluidizing stages 3 with nozzles 32 in configured in suitable pattern as schematically shown in Fig. 2a or Fig. 2b. Said pattern can be formed for example so that there are pipes 31 where the nozzles are attached at certain spacing. By the terminology fluidizing stages, it means fluidizing levels which are arranged within a certain vertical distance from each other. In other words, one fluidization stage comprises nozzles 32 for introducing reactive fluidizer substantially at one vertical level. In other words, reactive fluidizer will be introduced through the nozzles 32 so as to fluidize solid particles and participate in the reaction. Vertical distance between fluidizing stages or levels may be equally distributed, meaning a constant distance in vertical direction between each other. Accordingly, it is thus ensured proper fluidization velocities and dispersion of solid particles in the reactor chamber from bottom to top. Sizes and/or shapes of nozzles 32 may vary in the fluidizing stage and/or fluidizing stages so as to provide advantageous fluidization and reaction.

[0032] Pipes 31 forms a manifold for steam or some other suitable reactive flu- idizer or fluidizing agent, such as air or oxygen. Pipes 31 cross-section may have a circular cross-section or rectangular cross-section to name a few preferable cross-sections. In Fig. 1 the heat exchangers are arranged in a basic configuration, one heat exchanger 4 layer arranged per each fluidizing stage 3. However, it may be altered so that the number of heat exchangers 4 is greater than the number of fluidizing stages 3 or the number of heat exchangers 4 is smaller than the number of fluidizing stages 3. One heat exchanger 4 comprises at least one heat exchanger inlet 41 and at least one heat exchanger outlet 42 for heat transfer media (water, steam, some other fluid) to transfer the heat from the reactor 1 . The heat exchanger inlets 41 and outlets 42 may be grouped in a suitable way, they may in an embodiment be connected in series or in parallel and the origin of the fluid for the heat exchanger may be from any suitable source. Also the target for the heated fluid from the heat exchanger may be any suitable. The actual configuration of heat exchangers is a matter of reactor or plant design, the inner walls may be formed of heat exchangers or the heat exchangers may be configured extending in a radial direction in to the reactor chamber 10 (as shown in Fig. 2a) and transfer of heat into the heat exchangers 4 may be based for example on convection or conduction. The heat exchangers may comprise tubes and may be configured to extent into the reactor chamber as tube bundles (not shown in figures). Since the reaction and heat recovery can take place uniformly in the reactor, temperature of particles to be discharged is lowered. This means that the heat is recovered by the heat exchangers 4.

[0033] In Figures 2a and 2b, represent a horizontal cross-section of the reactor chamber of Figure 1 , there are schematically shown some possible configurations of nozzles 32 arranged on pipes 31 that forms a fluidizing stage 3. Through the nozzles reactive fluidizer is introduced into the reactor chamber 10. Through the nozzles also non-reactive fluidizer may be introduced into the reactor chamber 10. As all the figures of this disclosure are schematic, elements are not shown in scale and the relative dimensions are for illustrative purposes only. However, all the fluidizing stages 3 are configured within one compartment to enable efficient flow and reaction of CaO I Ca(OH)2 in the reactor chamber 10. Thus the pipes 31 shown in Fig. 2a and 2b are not forming a compartment for each fluidizing stage 3 but the material can pass the pipe 31 arrangement. Therefore, clogging of particles may be avoided or mitigated, and operational availability and efficiency are improved compared to known solutions. With the present configuration of the fluidization stages, or in other words, fluidization introduction stages, the reaction takes uniformly place in the reactor chamber.

[0034] In Fig. 3 it is presented still an embodiment of the reactor 1 where the fluidizing stages 3 are arranged so that there is a center pipe 31 to function as a manifold for nozzles 32 in the central area of the reactor chamber 10 and then there are nozzles arranged on the walls of the reactor chamber 10. The fluidizing effect is determined with suitable directioning of the nozzles 32 together with the velocity of the fluidizing media (steam, etc.). According to embodiment of Fig. 1 , 2a, 2b (as shown in cross section) and 3 the reactor 1 is circular in cross section perpendicular to a general flow direction and has its length greater than the width. This feature has an effect on the reaction time in the reactor, suitably the length, diameter and number of stages are the parameters to be selected for design the reactor. Other possible reactor cross section shapes are rectangular and polygonal such as hexagonal or octagonal. Heat exchangers are not shown in Figs. 2b and 3 but may be arranged as in Fig. 1 that is between the fluidizing stages. Similarly, as in figure 1 , one fluidization stage 3 is defined by a vertical distance of nozzles 32 at different vertical levels.

[0035] In Fig 4 it is presented schematically a system 100 for continuous storing and releasing thermochemical heat energy based on one of reaction by utilizing one of reaction:

1) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in elemental form + oxidizer in gaseous or vapor form such as steam, air or oxygen, or

2) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in oxidized form + hydrating compound in gaseous or vapor form in order to obtain hydroxide, the system comprises the reactor 1 and wherein the system 100 further comprises a storage 6 for feedstock and a storage 7 for end material, and a regeneration reactor 8 for a process of returning the end material back to feedstock, the system 100 is utilized in releasing heat when needed and storing heat when available. This storing and releasing energy or charging I discharging energy can be performed in one location or the charging can be performed where the energy is available and then the charged material is transported to a location where the energy is discharged from the material in a reactor of the present disclosure.

[0036] In operation of the system 100, 1) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in elemental form or 2) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in oxidized form will be considered as feedstocks storable in storage 6 and reacted compounds, or in other terms end product i.e. 1) oxidized or 2) hydrated (hydroxide) particles are the reaction material, considered as the end material storable in storage 7.

[0037] In Fig. 5 it is presented still an embodiment of a fluidized bed reactor (1) for continuous generation of thermochemical heat energy by utilizing one of reaction:

1) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in elemental form + an oxidizer in gaseous or vapor form such as steam or oxygen-containing gas or vapor, or

2) solid particles of alkaline earth metal or one of metals from a group consisting of lithium (Li), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe) and zinc (Zn), in oxidized form + a hydrating compound in gaseous or vapor form in order to obtain hydroxide, the reactor 1 comprising:

- a reactor chamber 10, - an inlet 2 arranged to the first end of the reactor chamber 10 for feeding the solid particles into the reactor 1 ,

- inside the reactor chamber 10 it is arranged an array of fluidizing stages 3, wherein each one of the fluidizing stages 3 comprises a number of nozzles 32 for fluidizing the solid particles with a reactive fluidizer, the oxidizer or the hydrating compound, to initiate and proceed with the reaction,

- fluidizing stages 3 are provided with one or more heat exchangers 4 for selectively recovering the heat released from the reaction,

- an outlet 5 is arranged at the opposite end to the first end of the reactor chamber 10 for exit of reaction material. In the embodiment the solid particles are used as a feedstock to the process, first stored in a storage 6, the fed through inlet 2 to the reactor 1 and reactor chamber 10, then fluidized and the reaction is initiated and proceed. In this embodiment there are configured two rows of fluidizing nozzles. The reactor may be provided with single nozzles 32, 32a for introducing a mixture of reactive fluidizer and non-reactive fluidizer into the reactor chamber, via same nozzles 32. In the embodiment of Fig. 5 the reactor is provided with two rows of nozzles 32, 32a, i.e. configured with separate nozzles so that it is provided nozzles 32 for reactive fluidizer and nozzles 32a for non-reactive fluidizer. This embodiment may be particularly suitable for materials that require more effort in fluidizing, i.e. more dense solid particle materials or such. If there are both reactive fluidizer and non-reactive fluidizer fed into the reactor chamber 10, a material (volume) input I output balance may be such that a separate gas exit channel 9 may be needed. Depending on the actual process conditions, the gas exit channel may be equipped with a particle separator or similar to avoid the solid particles to escape from the reactor chamber through that route. In cases that the process requires that an amount of reactive fluidizer is exceeding the actual amount participating in the reaction, such gas exit channel may be needed also with reactors 1 having only single type fluidizer feed, i.e. nozzles 32 for reactive fluidizer.

[0038] According to an embodiment of the present method, steam introduced as reactive fluidizer, temperature of the steam increases gradually, decreases gradually or stays the same from fluidizing stage 3 to consequent fluidizing stage 3. There may be many operation modes for the method and the reactor and the system. [0039] According to an embodiment of the present method, the steam velocity at steam nozzle 32 decreases or increases gradually from fluidizing stage 3 to consequent fluidizing stage 3.

[0040] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the invention, as defined in the appended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.

Part list

1 reactor

10 reactor chamber

11 inner wall

100 system

2 inlet

3 fluidizing stage

31 pipe

32, 32a nozzle

4 heat exchanger

41 heat exchanger inlet

42 heat exchanger outlet

5 outlet

6 storage (for feedstock)

7 storage (for end product)

8 regeneration reactor

9 gas exit channel