WO2013115316A1

WO2013115316A1 - Hydrothermal decomposition apparatus using internally-circulating fluidized bed, and hydrothermal decomposition method

Info

Publication number: WO2013115316A1
Application number: PCT/JP2013/052211
Authority: WO
Inventors: 児玉　竜也; 展之郷右近; 篤櫻井; 幸治松原
Original assignee: 国立大学法人新潟大学
Priority date: 2012-01-31
Filing date: 2013-01-31
Publication date: 2013-08-08
Also published as: JP5986589B2; JPWO2013115316A1

Abstract

Provided are: a hydrothermal decomposition apparatus that uses an internally-circulating fluidized bed that can be reused by reliably separating and recovering oxygen and hydrogen that have been generated, arbitrarily controlling each of the reaction temperature, reaction speed, reaction time and reaction zone of reactions that simultaneously proceed in the fluidized bed, and recovering reaction heat with high efficiency; and a hydrothermal decomposition method. The hydrothermal decomposition apparatus is provided with: a thermal reduction reactor (3) for carrying out thermal reduction reactions; a hydrothermal decomposition reactor (4) for carrying out hydrothermal decomposition reactions; a dispersion plate (8) for introducing a low oxygen partial pressure gas to the thermal reduction reactor (3), and a dispersion plate (9) for introducing water vapor to the hydrothermal decomposition reactor (4); an outlet (14) for recovering gas containing oxygen generated by the thermal reduction reactor (3); and an outlet (15) for recovering gas containing hydrogen generated by the hydrothermal decomposition reactor (4). The hydrothermal decomposition apparatus is configured in such a manner that a top communication port (6) and a bottom communication port (7), which are formed on a partition plate (5) that partitions the thermal reduction reactor (3) and the hydrothermal decomposition reactor (4), are buried inside the fluidized bed (2), and the fluidized bed (2) is able to directly flow between the thermal reduction reactor (3) and the hydrothermal decomposition reactor (4) through the top communication port (6) and the bottom communication port (7).

Description

Hydrothermal decomposition apparatus and hydrothermal decomposition method using internal circulating fluidized bed

The present invention relates to a hydrothermal decomposition apparatus and a hydrothermal decomposition method using an internal circulating fluidized bed.

A two-stage hydrothermal decomposition cycle with metal oxides such as iron oxide and cerium oxide is promising as a method for producing hydrogen by hydrothermal decomposition using heat of 1000 ° C or higher obtained by concentrating sunlight. The development of reactors for this purpose is being conducted by research institutions in each country.

The present inventors have developed a fluidized bed solar reactor in which metal oxide particles are circulated internally, and using this fluidized bed solar reactor, hydrogen that is two reactions of a two-stage hydrothermal decomposition cycle is developed. A method of simultaneously producing hydrogen and oxygen by developing a production reaction and an oxygen production reaction simultaneously in a reactor in which metal oxide particles flow in an internal circulation was developed (Patent Document 1).

As shown in FIG. 16, this fluidized bed type solar reactor includes a reactor 101 made of a stainless alloy and an inconel alloy, and this reactor 101 contains a fluidized bed 102 made of metal oxide particles. Yes. Inside the reactor 101, a cylindrical draft tube 103 opened in the vertical direction is provided. The draft tube 103 is buried in the fluidized bed 102 and disposed at the center of the fluidized bed 102. Further, at the bottom of the reactor 101,

dispersion plates

104 and 105 are provided at the center and the periphery, respectively.

Dispersion plates

104 and 105 are formed of a porous material so that particles of metal oxide constituting fluidized bed 102 can be held in reactor 101 and gas can be introduced from the bottom of reactor 101. ing. A quartz window 106 is provided on the ceiling of the reactor 101 so that sunlight can pass therethrough. In addition, a gas separator having a truncated cone shape is provided above the draft pipe 103 in order to divert the gas released upward from the inside of the draft pipe 103 and the gas released upward from the outside of the draft pipe 103. 107 is provided. Further, on the side of the upper part of the reactor 101, take-

out ports

108 and 109 for taking out the gas diverted by the gas separator 107 are provided. 201 is a ground reflector called a heliostat, and 202 is a tower reflector. The ground reflector 201 and the tower reflector 202 constitute a beam-down type condensing system. The beam-down type condensing system collects the sunlight S and irradiates the central portion of the upper surface of the fluidized bed 102 accommodated in the reactor 101.

Then, nitrogen is introduced from the dispersion plate 104 to the inside of the draft tube 103, and simultaneously, water vapor is introduced from the dispersion plate 105 to the outside of the draft tube 103. The fluidized bed 102 is circulated inside and outside the draft tube 103 by making the flow rate of nitrogen inside the draft tube 103 larger than the flow rate of water vapor outside the draft tube 103. That is, the fluidized bed 103 rises in a region inside the draft pipe 103, and an internal circulation flow is generated in which the fluidized bed 103 descends in a region between the outside of the draft pipe 103 and the reactor 101. Subsequently, the sunlight S collected by the ground reflecting mirror 201 and the tower reflecting mirror 202 is irradiated to the center of the upper surface of the fluidized bed 102 through the window 106 to heat the fluidized bed 102. In the vicinity of the center of the upper surface of the fluidized bed 102 irradiated with sunlight S, a high temperature portion H of 1400 ° C. or higher is formed, and a thermal reduction reaction proceeds at this high temperature portion H, and oxygen is released from the metal oxide particles. The The released oxygen passes through above the gas separator 107 and is collected from the outlet 108. The reduced metal oxide particles are sent to the lower part of the reactor 101 through the region between the outside of the draft tube 103 and the reactor 101 by the internal circulation flow. The temperature of the metal oxide particles decreases while being sent to the lower part of the reactor 101, and as a result, a low temperature part L of 1400 ° C. or lower is formed in the lower part of the fluidized bed 102. The hydrothermal decomposition reaction proceeds in the low temperature portion L, and the metal oxide particles reduced by the thermal reduction reaction become the original metal oxide even when oxidized, and hydrogen is generated at the same time. The generated hydrogen passes through the lower side of the gas separator 107 and is collected from the take-out port 109.

The above-described conventional method is characterized by focusing on the temperature distribution of the fluidized bed 103 formed by the irradiation of sunlight S, and causing the oxygen generation reaction and the hydrogen generation reaction to proceed simultaneously in the upper part and the lower part of the fluidized bed 103, respectively. To do. However, it has been found that this method has the following problems.
1 Due to the structure of the reactor, oxygen and hydrogen are mixed through the gap between the surface of the fluidized bed 102 and the gas separator 107 and a part of oxygen and hydrogen are recombined, so that the amount of hydrogen recovered decreases. When the gas separator 107 is brought into close contact with the surface of the fluidized bed 102 in order to prevent gas mixing through the gap, the internal circulation flow of the metal oxide particles is hindered and the two reactions proceed smoothly. It becomes difficult.
2 Although two reactions with different reaction temperatures proceed simultaneously at the upper and lower parts of the fluidized bed 102, it is difficult to arbitrarily control the two reaction temperatures.
3 While two reactions with different reaction rates proceed simultaneously in the upper and lower parts of the fluidized bed 102, the metal oxide particles rise inside the draft tube 103 and descend outside, but the two reaction times can be set arbitrarily. It is difficult to control and there is a limit to the increase in oxygen and hydrogen generation concentrations.
4 The hydrogen generation reaction that proceeds in the lower part of the fluidized bed 102 is an exothermic reaction, and the oxygen generation reaction that proceeds in the upper part of the fluidized bed 102 is an endothermic reaction, but the reaction time and reaction rate of each reaction are arbitrarily controlled. Therefore, it is difficult to sufficiently utilize the reaction heat (heat radiation amount) generated in the hydrogen generation reaction for the endothermic reaction in the oxygen generation, and it is difficult to improve the solar heat → hydrogen conversion efficiency.
5 A high-temperature portion H of 1400 ° C. or higher is formed in the vicinity of the center of the upper surface of the fluidized bed 102 irradiated with the sunlight S. However, due to the reactor structure, a part of the condensed sunlight S is a gas separator. The region between the outside of the draft tube 103 and the reactor 101 cannot be heated, and the utilization efficiency of solar energy is lowered.
6 Because of the structure of the reactor, a part of the vicinity of the center of the upper surface of the fluidized bed 102 is blocked by the gas separator 107, so it is difficult to widen the region of the high temperature portion H of 1400 ° C. or higher and increase the amount of oxygen produced. is there.
7 Due to the structure of the reactor, the region of the low temperature part L of 1400 ° C. or lower is limited to the lower part of the fluidized bed 102, and it is difficult to widen the region of the low temperature part L and increase the amount of hydrogen generation.
8 Because of the structure of the reactor, the metal oxide particles in the high temperature portion H formed in the vicinity of the center of the upper surface of the fluidized bed 102 quickly move to the region between the outside of the draft tube 103 and the reactor 101. It is difficult to recover and reuse the high-temperature sensible heat of 1400 ° C. or higher possessed by the metal oxide particles in the high-temperature portion H as exhaust heat.

WO2011 / 068122 International pamphlet

Therefore, in view of the above problems, the present invention can reliably separate and recover the generated oxygen and hydrogen, and can arbitrarily set the reaction temperature, reaction rate, reaction time, and reaction region of the reaction that proceeds simultaneously in the fluidized bed. It is also possible to provide a hydrothermal decomposition apparatus and hydrothermal decomposition method using an internal circulating fluidized bed that can be controlled to high temperature, and can recover and reuse high-temperature heat as exhaust heat with high efficiency. And

The hydrothermal decomposition apparatus using the internal circulation fluidized bed according to the present invention condenses sunlight into a reactor containing a fluidized bed made of metal oxide particles and the fluidized bed contained in the reactor. The solar light collecting means for irradiating, the reactor comprising: a thermal reduction reactor for performing a thermal reduction reaction; a hydrothermal decomposition reactor for performing a hydrothermal decomposition reaction; and a low oxygen content from below to the thermal reduction reactor. Low oxygen partial pressure gas introducing means for introducing pressurized gas, steam introducing means for introducing water vapor into the hydrothermal decomposition reactor from below, and oxygen recovery for recovering gas containing oxygen generated from the thermal reduction reactor And a hydrogen recovery means for recovering a gas containing hydrogen generated from the hydrothermal decomposition reactor, wherein the interior of the thermal reduction reactor and the interior of the hydrothermal decomposition reactor are in communication with the upper communication port and the lower communication port. The upper communication port and the lower communication port The fluidized bed is buried in the fluidized bed so that the fluidized bed can flow between the thermal reduction reactor and the hydrothermal decomposition reactor through the upper communication port and the lower communication port, Sunlight is irradiated to the upper surface of the fluidized bed accommodated in the thermal reduction reactor by a light collecting means.

The thermal reduction reactor and the hydrothermal decomposition reactor are partitioned by a partition plate, and the interior of the thermal reduction reactor and the interior of the hydrothermal decomposition reactor are upper communication ports formed in the partition plate. And the lower communication port, the upper communication port and the lower communication port are buried in the fluidized bed, and through the upper communication port and the lower communication port, the thermal reduction reactor The fluidized bed is configured to flow directly between the hydrothermal decomposition reactors.

Further, the upper communication port and the lower communication port are provided with screw conveyors for conveying the fluidized bed between the thermal reduction reactor and the hydrothermal decomposition reactor.

In addition, an enlarged portion that expands the horizontal cross-sectional area of the thermal reduction reactor upward is formed in the upper portion of the thermal reduction reactor, and a quartz window through which sunlight passes is formed in the upper portion of the enlarged portion. It is characterized by having.

Also, the thermal reduction reactor and the hydrothermal decomposition reactor are configured separately from each other.

A conveying means for conveying the fluidized bed between the thermal reduction reactor and the hydrothermal decomposition reactor between an upper communication port of the thermal reduction reactor and a lower communication port of the hydrothermal decomposition reactor; Provided, the lower communication port of the thermal reduction reactor and the upper communication port of the hydrothermal decomposition reactor are in direct communication with each other.

Further, a moving means for moving the fluidized bed in the thermal reduction reactor is provided inside the thermal reduction reactor.

The hydrothermal decomposition method using the inner circulating fluidized bed according to the present invention uses the hydrothermal decomposition apparatus using the inner circulating fluidized bed according to the present invention, and converts the fluidized bed into the thermal reduction reactor and the hydrothermal decomposition reactor. The oxygen generation reaction in which a part of the fluidized bed is heated by sunlight in a low oxygen partial pressure gas atmosphere while releasing the oxygen from the metal oxide, and the metal after releasing the oxygen. It is characterized in that two reactions of a hydrogen generation reaction in which water vapor is brought into contact with the oxide to generate hydrogen simultaneously proceed.

Further, the oxygen generation reaction proceeds at 1400 ° C. or higher, and the hydrogen generation reaction proceeds at 1400 ° C. or lower.

Further, the metal oxide is characterized by being ferrite or zirconia supporting ferrite.

Further, the zirconia is any of monoclinic zirconia, cubic zirconia, and tetragonal zirconia, and the cubic zirconia contains any of yttria, calcia, and magnesia as a stabilizer.

Further, the metal oxide is characterized by nickel ferrite or monoclinic zirconia supporting nickel ferrite.

The metal oxide is cerium oxide or zirconia supporting cerium oxide.

The particle size of the metal oxide particles is 100 to 750 μm.

Further, the low oxygen partial pressure gas is nitrogen or argon.

According to the hydrothermal decomposition apparatus and hydrothermal decomposition method using the inner circulation fluidized bed of the present invention, the thermal reduction reactor and the hydrothermal decomposition reactor are partitioned by the partition plate, and the interior of the thermal reduction reactor and the water are separated. The interior of the pyrolysis reactor communicates directly with the upper communication port and the lower communication port formed in the partition plate, and the upper communication port and the lower communication port are buried in the fluidized bed, Since the fluidized bed can flow directly between the thermal reduction reactor and hydrothermal decomposition reactor through the lower communication port, oxygen generated in the thermal reduction reactor and generated in the hydrothermal decomposition reactor The reaction temperature, reaction rate, reaction time and reaction region of the two reactions that proceed simultaneously in the fluidized bed of the thermal reduction reactor and the fluidized bed of the hydrothermal decomposition reactor Each can be controlled easily Can, furthermore, it is possible to recover the heat of reaction at a high efficiency occurring in the hydrothermal decomposition reactor for reuse in the heat reduction reactor. Furthermore, the high-temperature heat generated in the thermal reduction reactor and the hydrothermal decomposition reactor can be recovered and reused as waste heat with high efficiency.

That is, the present invention can solve the problems of the conventional methods as follows.
1 Since oxygen and hydrogen are generated separately in the thermal reduction reactor and hydrothermal decomposition reactor, respectively, there is no need for gas separation of oxygen and hydrogen by a gas separator or the like, and the purity of recovered oxygen and hydrogen is reduced. Will improve.
2 Since the thermal reduction reaction and hydrothermal decomposition reaction proceed in the thermal reduction reactor and hydrothermal decomposition reactor, respectively, it becomes easy to arbitrarily control the reaction temperatures of the two reactions having different reaction temperatures. Oxygen generation and hydrogen generation from the reactor are improved.
3 Since the thermal reduction reaction and hydrothermal decomposition reaction proceed in the thermal reduction reactor and hydrothermal decomposition reactor, respectively, it becomes easy to arbitrarily control the two reaction times, and the amount of oxygen generated in each reactor In addition, the hydrogen generation amount is improved, and the generation concentration of recovered oxygen and hydrogen is improved.
4 Since the thermal reduction reaction and hydrothermal decomposition reaction proceed in the thermal reduction reactor and hydrothermal decomposition reactor, respectively, it is easy to arbitrarily control the reaction time and reaction rate of each reaction, and the hydrogen generation reaction The reaction heat (amount of heat released) generated in the process can be fully utilized for the endothermic reaction in the generation of oxygen, improving the efficiency of solar heat → hydrogen conversion.
5 Concentrated sunlight is widely irradiated in the vicinity of the upper surface of the fluidized bed in the thermal reduction reactor without being blocked by the gas separator, and can contribute to the formation of a high-temperature part of 1400 ° C or higher. In addition, it can be used for heating metal oxide particles, and the utilization efficiency of solar energy is increased.
6 Since the collected sunlight can be widely irradiated in the vicinity of the upper surface of the fluidized bed in the thermal reduction reactor without being blocked by the gas separator, it can contribute to the formation of a high temperature portion of 1400 ° C. or higher. The region of the high temperature part can be expanded, and the amount of oxygen produced can be increased.
7 Because of the structure of the reactor, the size of the hydrothermal cracking reactor can be changed arbitrarily, so that the region of the low temperature part below 1400 ° C formed in the hydrothermal cracking reactor can be expanded, and the amount of hydrogen produced Can be increased.
8 Because of the structure of the reactor, the metal oxide particles in the high temperature part formed in the vicinity of the upper surface of the fluidized bed in the thermal reduction reactor have an upper communication port located below the upper surface of the fluidized bed. Since some of them stay around the high temperature part H and are heated to a higher temperature, the thermal reduction reaction is more likely to proceed, and the amount of oxygen generated is improved.
9 Because of the structure of the reactor, the metal oxide particles in the high temperature part formed in the vicinity of the upper surface of the fluidized bed in the thermal reduction reactor have an upper communication port located below the upper surface of the fluidized bed. A part of the stagnation stays around the high-temperature part H, and the high-temperature sensible heat of 1400 ° C. or higher possessed by the metal oxide particles of the high-temperature part H can be recovered and reused as exhaust heat with high efficiency.

It is a schematic diagram which shows one Example of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of this invention. The simulation model in Example 2 is shown. The calculation result figure which shows the time change of the particle | grain volume fraction in Example 2 is shown. It is a calculation result figure which shows the time average flow velocity vector of the particle | grains and gas in Example 2. FIG. 6 is a graph showing a change over time in the hydrogen production rate produced from the hydrothermal decomposition reactor 4 in Example 3. FIG. 6 is a graph obtained by measuring changes with time in oxygen generation rate generated from the thermal reduction reactor 3 in Example 3 and hydrogen flowing in from the hydrothermal decomposition reactor 4. FIG. 6 is a graph obtained by measuring changes over time in the hydrogen production rate produced from the hydrothermal decomposition reactor 4 in Example 4 and oxygen flowing in from the thermal reduction reactor 3. FIG. 6 is a graph obtained by measuring changes with time in the oxygen generation rate generated from the thermal reduction reactor 3 in Example 4 and hydrogen flowing in from the hydrothermal decomposition reactor 4. FIG. 6 is a graph showing a change over time in a hydrogen / oxygen generation rate ratio, which is a value obtained by dividing the hydrogen generation rate generated from the hydrothermal decomposition reactor 4 in Example 4 by the oxygen generation rate generated from the thermal reduction reactor 3. It is a schematic diagram which shows another Example of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of this invention. It is a schematic diagram from the upper surface which shows another Example of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of this invention. It is a schematic diagram which shows another Example of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of this invention. It is a schematic diagram which shows another Example of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of this invention. It is a schematic diagram which shows another Example of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of this invention. It is a schematic diagram which shows another Example of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of this invention. It is a schematic diagram which shows an example of the hydrothermal decomposition apparatus using the conventional internal circulation fluidized bed.

Hereinafter, embodiments of the hydrothermal decomposition apparatus and hydrothermal decomposition method using the inner circulating fluidized bed of the present invention will be described with reference to the accompanying drawings. In addition, the hydrothermal decomposition apparatus and hydrothermal decomposition method using the internal circulation fluidized bed of this invention are suitably implemented in the sun belt area whose solar radiation is 1800 kWh / m < ² > or more per year.

First, the structure of the hydrothermal decomposition apparatus using the internal circulation fluidized bed of a present Example is demonstrated.
In FIG. 1 showing an embodiment of a hydrothermal decomposition apparatus using an internal circulating fluidized bed of the present invention, 1 is a reactor made of a stainless alloy and an Inconel alloy, and this reactor 1 contains metal oxide particles. A fluidized bed 2 as an inner circulating fluidized bed is housed.

Examples of the metal oxide include iron oxides such as Fe ₃ O ₄ , NiFe ₂ O ₄ , and CoFe ₂ O ₄ , iron oxides containing multiple metals, and these iron oxides supported on a carrier such as zirconia. Cerium oxide (CeO ₂ ), cerium oxide supported on a carrier such as zirconia, or iron ions or cerium ions dissolved in zirconia can be used. As the zirconia, any of monoclinic zirconia, cubic zirconia, and tetragonal zirconia can be used. Note that cubic zirconia is stabilized zirconia or partially stabilized zirconia containing a stabilizer such as yttria, calcia, and magnesia, and includes zirconia containing at least cubic crystals as a crystal layer. Preferably, the metal oxide particles include ferrite fine powder represented by MFe ₂ O ₄ (M = Fe, Zn, Mn, Ni, Co, Mg), MFe ₂ O ₄ / m-ZrO ₂ (M = Fe, Zn, Mn, Ni, Co, Mg) Monoclinic zirconia fine powder supporting ferrite represented by MFE ₂ O ₄ / YSZ (M = Fe, Zn, Mn, Ni, Co, Mg) The fine powder of yttria-stabilized cubic zirconia carrying the ferrite represented by More preferably, fine powders of NiFe ₂ O ₄ and NiFe ₂ O ₄ / m-ZrO ₂ are used. Further, a fine powder of cerium oxide and a fine powder of zirconia supporting cerium oxide are also preferably used. The size of the metal oxide particles is preferably 30 to 1000 μm, more preferably 100 to 750 μm, in order to maintain the fluidity of the fluidized bed 2.

In addition, zirconia supporting ferrite, for example, disperses zirconia fine powder in an aqueous solution of Fe (II) salt and adds an alkaline aqueous solution such as an aqueous solution of sodium hydroxide to form a colloid of Fe (II) hydroxide. This is oxidized by bubbling air, and after the colloid of Fe (II) hydroxide is dissolved in the aqueous solution, the dissolution precipitation reaction that precipitates as Fe ₃ O ₄ proceeds to disperse fine zirconia powder It can be obtained by growing Fe ₃ O ₄ on the body. Alternatively, a fine powder of zirconia is dispersed in an aqueous solution of Fe (II) salt, this is evaporated to dryness, and then fired to convert the Fe (II) salt on zirconia into a metal oxide. It can also be obtained by baking at a temperature of 0 ° C. or higher.

The reactor 1 includes a thermal reduction reactor 3 that performs a thermal reduction reaction and a hydrothermal decomposition reactor 4 that performs a hydrothermal decomposition reaction. The thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 are partitioned by a single partition plate 5, and the interior of the thermal reduction reactor 3 and the interior of the hydrothermal decomposition reactor 4 are located above the partition plate 5. An upper communication port 6 that directly communicates with each other is formed, and a lower communication port 7 that directly communicates the interior of the thermal reduction reactor 3 and the interior of the hydrothermal decomposition reactor 4 is formed at the lower portion of the partition plate 5. Has been. Further, the upper communication port 6 and the lower communication port 7 are buried in the fluidized bed 2. The fluidized bed 2 can flow directly between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 through the upper communication port 6 and the lower communication port 7.

In the lower part of the thermal reduction reactor 3, a dispersion plate 8 for introducing a low oxygen partial pressure gas such as nitrogen into the thermal reduction reactor 3, and in the lower part of the hydrothermal decomposition reactor 4, there is a hydrothermal decomposition reactor. A dispersion plate 9 for introducing water vapor into 4 is provided. The

dispersion plates

8 and 9 are connected to the lowermost part 7 ′ of the lower communication port 7 so as not to hinder the flow of the fluidized bed 2 at the lower communication port 7. The surface of the dispersion plate 8 substantially coincides with the height of the lowermost part 7 ′ of the lower communication port 7, and the dispersion plate 9 is provided inclined with the lowermost part 7 ′ of the lower communication port 7 as the lowest part. . Further, the

dispersion plates

8 and 9 are made of a porous material so that the metal oxide particles constituting the fluidized bed 2 can be held in the reactor 1 and gas can be introduced from the bottom of the reactor 1. Is formed. An introduction pipe 10 for introducing a low oxygen partial pressure gas is provided at the bottom of the thermal reduction reactor 3, and an introduction pipe 11 for introducing water vapor is provided at the bottom of the hydrothermal decomposition reactor 4.

The upper part of the thermal reduction reactor 3 is connected to the side wall of the thermal reduction reactor 3 and the partition plate 5 above the uppermost part 6 ′ of the upper communication port 6, and the horizontal side of the thermal reduction reactor 3 upwards. An enlarged portion 12 that enlarges the cross-sectional area is formed. The enlarged portion 12 allows sunlight S to be irradiated to the fluidized bed 2 without being blocked by the wall of the thermal reduction reactor 3. A quartz window 13 is provided on the ceiling above the enlarged portion 12 of the thermal reduction reactor 3 so that sunlight can pass therethrough. On the side of the upper part of the enlarged portion 12 of the thermal reduction reactor 3, there is provided a gas outlet 14 for containing oxygen generated by the thermal reduction reaction. An outlet 15 for extracting gas containing hydrogen generated by the decomposition reaction is provided.

201 is a ground reflector called a heliostat, 202 is a tower reflector installed in a tower (not shown), and the ground reflector 201 and the tower reflector 202 constitute a beam-down type condensing system. The beam-down type condensing system collects sunlight S and irradiates the upper surface of the fluidized bed 2 accommodated in the thermal reduction reactor 3.

Next, a hydrothermal decomposition method using a hydrothermal decomposition apparatus using the inner circulating fluidized bed of this embodiment will be described.

A low oxygen partial pressure gas is introduced from the dispersion plate 8 into the thermal reduction reactor 3, and at the same time, water vapor is introduced from the dispersion plate 9 into the hydrothermal decomposition reactor 4. As the low oxygen partial pressure gas, for example, nitrogen having a purity of 99.999% is used. Here, the low oxygen partial pressure gas introduced into the thermal reduction reactor 3 may be a gas having a low oxygen partial pressure, and is not limited to nitrogen, and may be, for example, argon. Moreover, the gas introduce | transduced into the hydrothermal decomposition reactor 4 should just contain water vapor | steam, for example, the mixed gas of water vapor | steam and nitrogen may be sufficient as it. Then, the fluidized bed 2 is circulated between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 by making the flow rate of nitrogen larger than the flow rate of water vapor. That is, the fluidized bed 2 rises in the thermal reduction reactor 3, and an internal circulation flow in which the fluidized bed 2 descends in the hydrothermal decomposition reactor 4 is generated.

Subsequently, the fluidized bed 2 is heated by irradiating the fluidized bed 2 with the sunlight S collected by the ground reflector 201 and the tower reflector 202 through the window 13. In the vicinity of the upper surface of the fluidized bed 2 in the thermal reduction reactor 3 irradiated with the sunlight S, a high-temperature portion H of 1400 ° C. or higher is formed, and the thermal reduction reaction proceeds at the high-temperature portion H to form metal oxide particles. Releases oxygen. The released oxygen is collected from the outlet 14.

For example, when NiFe ₂ O ₄ is used as the metal oxide, the reaction formula of the thermal reduction reaction is as follows.
NiFe ₂ O ₄ → 3Ni _1/3 Fe _2/3 O + (1/2) O ₂

For example, when CeO ₂ is used as the metal oxide, the reaction formula of the thermal reduction reaction is as follows.
CeO ₂ → CeO _2−x + (x / 2) O ₂ (0 <x ≦ 0.5)

The reduced metal oxide particles are sent to the hydrothermal decomposition reactor 4 through the upper communication port 6 by internal circulation flow. The temperature of the metal oxide particles decreases while flowing in the hydrothermal decomposition reactor 4, and as a result, the fluidized bed 2 in the hydrothermal decomposition reactor 4 has a temperature of 1400 ° C or less, preferably 1200 ° C or less. More preferably, a low temperature portion L of 1000 ° C. or lower is formed. The hydrothermal decomposition reaction proceeds in the low temperature portion L, and the metal oxide particles reduced by the thermal reduction reaction become the original metal oxide even when oxidized, and hydrogen is generated at the same time. The generated hydrogen is recovered from the extraction port 15.

For example, when NiFe ₂ O ₄ is used as the metal oxide, the reaction formula of the hydrothermal decomposition reaction is as follows.
3Ni _1/3 Fe _2/3 O + H ₂ O → NiFe ₂ O ₄ + H ₂

For example, when CeO ₂ is used as the metal oxide, the reaction formula of the hydrothermal decomposition reaction is as follows.
CeO _2-x + xH ₂ O → CeO ₂ + xH ₂ (0 <x ≦ 0.5)

Also, heat moves from the fluidized bed 2 of the hydrothermal decomposition reactor 4 to the fluidized bed 2 below the thermal reduction reactor 3 through the partition plate 5. In order for the heat transfer to proceed smoothly, the temperature of the fluidized bed 2 at the lower part of the thermal reduction reactor 3 is lower than the temperature of the fluidized bed 2 of the hydrothermal decomposition reactor 4, and a sufficient temperature difference is required. . In the fluidized bed 2 of the present embodiment, nitrogen is introduced into the thermal reduction reactor 3 and water vapor is simultaneously introduced into the hydrothermal decomposition reactor 4, and the flow rate of nitrogen is made larger than the flow rate of water vapor to make the fluidized bed 2 into the reactor. 1, a large temperature difference is formed between the fluidized bed 2 at the lower part of the thermal reduction reactor 3 and the fluidized bed 2 of the hydrothermal decomposition reactor 4, and heat is generated from the fluidized bed 2 of the hydrothermal decomposition reactor 4. Heat transfer can be performed toward the fluidized bed 2 of the reduction reactor 3. That is, the sensible heat of the reaction particles in the fluidized bed 2 in the low temperature part L is recovered by the reaction particles in the fluidized bed 2 that are moving from the low temperature part L to the high temperature part H. In addition, since the reaction particles of the fluidized bed 2 in the low temperature part L generate heat due to the hydrogen generation reaction, the reaction heat is transferred to the reaction particles of the fluidized bed 2 in the middle of moving from the low temperature part L to the high temperature part H. It can be used as a heat source for an oxygen generation reaction that is an endothermic reaction. Furthermore, since it takes some time for the reaction particles to move in the low temperature portion L, a large amount of heat can be transferred to the reaction particles moving from the low temperature portion L to the high temperature portion H. Therefore, energy efficiency is improved.

As described above, the hydrothermal decomposition apparatus using the inner circulation fluidized bed of the present embodiment includes the reactor 1 that contains the fluidized bed 2 made of metal oxide particles, and the fluid that is contained in the reactor 1. The ground reflecting mirror 201 and the tower reflecting mirror 202 as sunlight collecting means for collecting and irradiating the sunlight S on the layer 2 are provided, and the reactor 1 includes a thermal reduction reactor 3 that performs a thermal reduction reaction, A hydrothermal decomposition reactor 4 for performing a hydrothermal decomposition reaction, a dispersion plate 8 and an introduction pipe 10 as low oxygen partial pressure gas introduction means for introducing a low oxygen partial pressure gas into the thermal reduction reactor 3 from below; Dispersion plate 9 and introduction pipe 11 as water vapor introduction means for introducing water vapor into hydrothermal decomposition reactor 4 from below, and oxygen recovery means for recovering the gas containing oxygen generated from thermal reduction reactor 3 Collects hydrogen-containing gas generated from the outlet 14 and the hydrothermal decomposition reactor 4 The thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 are partitioned by a partition plate 5 and the interior of the thermal reduction reactor 3 and the hydrothermal heat. The inside of the decomposition reactor 4 is directly communicated with an upper communication port 6 and a lower communication port 7 formed in the partition plate 5, and the upper communication port 6 and the lower communication port 7 are connected to the fluidized bed 2. The fluidized bed 2 can be directly flowed between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 through the upper communication port 6 and the lower communication port 7. The solar reflecting light is applied to the upper surface of the fluidized bed 2 accommodated in the thermal reduction reactor 3 by the ground reflecting mirror 201 and the tower reflecting mirror 202 as the sunlight collecting means. is there.

In addition, an enlarged portion 12 that expands the horizontal cross-sectional area of the thermal reduction reactor 3 upward is formed in the upper portion of the thermal reduction reactor 3, and sunlight S is transmitted through the upper portion of the enlarged portion 12. A quartz window 13 is provided.

The hydrothermal decomposition method using the inner circulation fluidized bed of this embodiment uses the hydrothermal decomposition apparatus using the inner circulation fluidized bed of this embodiment, and the dispersion plate 8 as the low oxygen partial pressure gas introduction means and By making the flow rate of the low oxygen partial pressure gas introduced from the introduction pipe 10 larger than the flow rate of the water vapor introduced from the dispersion plate 9 and the introduction pipe 11 as the steam introduction means, the fluidized bed 2 is subjected to the thermal reduction reaction. While partly circulating between the vessel 3 and the hydrothermal decomposition reactor 4, a part of the fluidized bed 2 is heated by sunlight S in a low oxygen partial pressure gas atmosphere to release oxygen from the metal oxide. Two reactions of an oxygen generation reaction and a hydrogen generation reaction in which water vapor is brought into contact with the metal oxide after releasing oxygen to generate hydrogen are simultaneously advanced.

According to the hydrothermal decomposition apparatus and hydrothermal decomposition method using the inner circulating fluidized bed of this embodiment, the oxygen generation reaction in the thermal reduction reactor 3 and the hydrogen generation reaction in the hydrothermal decomposition reactor 4 proceed simultaneously. Therefore, the recovery of oxygen and hydrogen can be performed continuously. Further, the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 are clearly partitioned by a partition plate 5 and are generated because oxygen is generated in the thermal reduction reactor 3 and hydrogen is generated in the hydrothermal decomposition reactor 4. There is no mixing of oxygen and hydrogen. Therefore, the generated oxygen and hydrogen can be reliably separated and recovered. As a result, the purity of the recovered hydrogen can be improved and the production cost of hydrogen can be reduced. In addition, since two reactions with different reaction temperatures proceed separately in the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4, it is easy to control the reaction temperature and reaction time of the reactions that proceed simultaneously. Efficiency is improved, and oxygen and hydrogen generation concentrations are improved. In addition, since it becomes easy to control the amount of heat released in an exothermic reaction and the amount of heat absorbed in an endothermic reaction, the reaction heat can be recovered and reused with high efficiency, energy loss is reduced, and solar energy is used. Efficiency is improved. In addition, the use of waste heat from the gas at a constant temperature generated from each of the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 is facilitated, so that the energy loss is further reduced and the utilization efficiency of solar energy is improved. .

For the hydrothermal decomposition apparatus using the inner circulating fluidized bed of Example 1, under the calculation conditions shown in FIG.
FLUENT ver.13) was used to conduct a fluidization simulation on the behavior of fluidized particles and circulating gas in the reactor 1. In this simulation, the compressible Navier-Stokes equation was adopted as a physical model for solid-gas multiphase flow, and the Euler-granular model was applied to the interaction between particles and gas. Furthermore, in the heat transfer analysis of the fluidized bed 2, the energy equation and the radiation transport equation were combined, and the amount of radiant heat transfer was analyzed by the spherical harmonic function method. The fluidized bed 2 was filled with CeO ₂ particles having a diameter of 450 μm in the reactor 1.

The results are shown in FIGS. FIG. 3 shows the volume fraction of the solid phase, which progresses in time from the upper left to the lower right. From this result, it was found that bubbles were generated from the lower inlet. From the particle flow velocity distribution (left side of FIG. 4), it was found that the flowing particles flow in an internal circulation between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4. Further, from the gas flow velocity distribution (right in FIG. 4), the oxygen produced in the thermal reduction reactor 3 and the hydrogen produced in the hydrothermal decomposition reactor 4 are not mixed with each other, and the reactor is separated from oxygen and hydrogen. It was found that it could be taken out of 1.

Using 1429 g of fine powder of CeO ₂ having a particle size of 106 to 710 μm as the metal oxide constituting the fluidized bed 2, a thermal reduction reaction and a hydrothermal decomposition reaction were simultaneously performed. The width and depth of the thermal reduction reactor 3 of the reactor 1 used were both 60 mm, and the width and depth of the hydrothermal decomposition reactor 4 were both 40 mm. Moreover, 5.1 kW light was irradiated using three 7 kW xenon lamps instead of sunlight S. Then, nitrogen having a purity of 99.999% is flowed to the thermal reduction reactor 3 at a flow rate of 8 L / min and a linear flow velocity of 2.22 m / min, and the hydrothermal decomposition reactor 4 is a mixed gas of water vapor and nitrogen. At a flow rate of 4 L / min and a linear flow rate of 1.77 m / min. The types of gas produced from the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 and their production rates were quantitatively analyzed with a mass spectrometer and a gas chromatograph.

FIG. 5 shows the change over time in the amount of hydrogen generated from the hydrothermal decomposition reactor 4 at this time. The total amount of hydrogen generated from the hydrothermal decomposition reactor 4 was 554 ml (1 atm, 25 ° C.). Moreover, the production | generation of oxygen was not seen from the gas exhaust port connected to the hydrothermal decomposition reactor 4. FIG. From this result, it can be seen that oxygen generated from the thermal reduction reactor 3 is not mixed into the hydrothermal decomposition reactor 4.

FIG. 6 shows the change over time in the amount of oxygen generated from the thermal reduction reactor 3. The total amount of oxygen generated from the thermal reduction reactor 3 was 318 ml (1 atm, 25 ° C.). No hydrogen was produced from the gas outlet connected to the thermal reduction reactor 3. From this result, it can be seen that the hydrogen generated in the hydrothermal decomposition reactor 4 does not enter the thermal reduction reactor 3.

From these results, it was proved that the generated oxygen and hydrogen did not recombine in the reactor, and the separation of the reactor worked.

Moreover, the fluidized bed 2 after the reaction did not sinter and agglomerate and had a powder form. Therefore, when CeO ₂ fine powder was used for the fluidized bed 2, it was confirmed that the oxygen generation amount and the hydrogen generation amount can be increased by further extending the reaction time.

Using 1391 g of CeO ₂ fine powder having a particle size of 106 to 710 μm as the metal oxide constituting the fluidized bed 2, a thermal reduction reaction and a hydrothermal decomposition reaction were simultaneously performed. The width and depth of the thermal reduction reactor 3 of the reactor 1 used were both 60 mm, and the width and depth of the hydrothermal decomposition reactor 4 were both 40 mm. Moreover, 5.1 kW light was irradiated using three 7 kW xenon lamps instead of sunlight S. Then, nitrogen having a purity of 99.999% is flowed through the thermal reduction reactor 3 at a flow rate of 13 L / min, and a mixed gas of water vapor and nitrogen is flowed through the hydrothermal decomposition reactor 4 at a flow rate of 4.5 L / min. Shed at speed. The kind of gas produced from the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 and the production rate thereof were quantitatively analyzed by a mass spectrometer.

FIG. 7 shows the change over time in the amount of hydrogen generated from the hydrothermal decomposition reactor 4 at this time. The total amount of hydrogen generated from the hydrothermal decomposition reactor 4 was 847 ml (1 atm, 25 ° C.). Also, almost no oxygen was generated from the gas outlet connected to the hydrothermal decomposition reactor 4. From this result, it can be seen that oxygen generated from the thermal reduction reactor 3 is not mixed into the hydrothermal decomposition reactor 4.

FIG. 8 shows the change over time in the amount of oxygen generated from the thermal reduction reactor 3. The total amount of oxygen generated from the thermal reduction reactor 3 was 1319 ml (1 atm, 25 ° C.). Almost no hydrogen was generated from the gas outlet connected to the thermal reduction reactor 3. From this result, it can be seen that hydrogen produced in the hydrothermal decomposition reactor 4 does not enter the thermal reduction reactor 3.

FIG. 9 shows the change over time in the hydrogen / oxygen generation rate ratio, which is a value obtained by dividing the hydrogen generation rate generated from the hydrothermal decomposition reactor 4 by the oxygen generation rate generated from the thermal reduction reactor 3. It can be seen that the hydrogen / oxygen ratio produced over time approaches 2 which is the stoichiometric ratio of water molecules (H ₂ O). Therefore, it can be seen that the two-stage hydrothermal decomposition reaction in the reactor proceeds according to the stoichiometric ratio.

Next, an example in which a screw conveyor is used to move metal oxide particles between the thermal reduction reactor and the hydrothermal decomposition reactor will be described. In addition, the same code | symbol is attached | subjected to the same part as the said Example 1, and description of the part is abbreviate | omitted.

In FIG. 10 showing the hydrothermal decomposition apparatus using the inner circulating fluidized bed of the present embodiment, the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 are configured separately from each other.

Upper communication ports

6a and 6b communicating the inside of the thermal reduction reactor 3 and the inside of the hydrothermal decomposition reactor 4 are formed at the upper parts of the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4, respectively.

Lower communication ports

7 a and 7 b that communicate the inside of the thermal reduction reactor 3 and the inside of the hydrothermal decomposition reactor 4 are formed in the lower part of the vessel 3 and the hydrothermal decomposition reactor 4, respectively. The

upper communication ports

6 a and 6 b and the

lower communication ports

7 a and 7 b are buried in the fluidized bed 2.

A screw conveyor 21 is provided between the

upper communication ports

6a and 6b, and the fluidized bed 2 is transported from the thermal reduction reactor 3 to the hydrothermal decomposition reactor 4. A screw conveyor 22 is provided between the

lower communication ports

7 a and 7 b so that the fluidized bed 2 is transported from the hydrothermal decomposition reactor 4 to the thermal reduction reactor 3. The screw conveyors 21 and 22 are driven by

motors

23 and 24, respectively, and the rotational speeds of the

screw conveyors

21 and 22 are configured to be controllable. The fluidized bed 2 can flow between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 through the

upper communication ports

6a and 6b and the

lower communication ports

7a and 7b.

dispersion plates

8 and 9 are provided so as to be connected to the lowermost portions 7a 'and 7b' of the

lower communication ports

7a and 7b so as not to disturb the flow of the fluidized bed 2 at the lower communication port 7. The surface of the dispersion plate 8 substantially coincides with the height of the lowermost portion 7a ′ of the lower communication port 7a, and the distribution plate 9 is provided inclined with the lowermost portion 7b ′ of the lower communication port 7b as the lowest portion. .

In addition, as shown to Fig.11 (a), the two

screw conveyors

21 and 22 may be located on the line which connects the center of the thermal reduction reactor 3, and the center of the hydrothermal decomposition reactor 4, FIG. As shown in b), the two

screw conveyors

21 and 22 may be located on the same line connecting a portion away from the center of the thermal reduction reactor 3 and a portion away from the center of the hydrothermal decomposition reactor 4. As shown in FIG. 11 (c), the two

screw conveyors

21 and 22 are located on separate lines connecting a portion away from the center of the thermal reduction reactor 3 and a portion away from the center of the hydrothermal decomposition reactor 4. A plurality of upper and lower screw conveyors may be arranged or may be inclined.

Further, the screws constituting the

screw conveyors

21 and 22 may be uniaxial or biaxial, and one of the

screw conveyors

21 and 22 may be omitted.

In the above configuration, a low oxygen partial pressure gas is introduced from the dispersion plate 8 to the thermal reduction reactor 3, and at the same time, water vapor is introduced from the dispersion plate 9 to the hydrothermal decomposition reactor 4. Then, the

screw conveyors

21 and 22 are driven by the

motors

23 and 24, and the fluidized bed 2 is transported from the thermal reduction reactor 3 to the hydrothermal decomposition reactor 4 through the

upper communication ports

6a and 6b. The fluidized bed 2 is circulated between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 by transporting the fluidized bed 2 from the hydrothermal decomposition reactor 4 to the thermal reduction reactor 3 through 7b. That is, the fluidized bed 2 rises in the thermal reduction reactor 3 and the fluidized bed 2 descends in the hydrothermal decomposition reactor 4 through the

upper communication ports

6a and 6b and the

lower communication ports

7a and 7b.

Subsequently, the fluidized bed 2 is irradiated with sunlight S through the window 13 to heat the fluidized bed 2. In the vicinity of the upper surface of the fluidized bed 2 in the thermal reduction reactor 3 irradiated with the sunlight S, a high-temperature portion H of 1400 ° C. or higher is formed, and the thermal reduction reaction proceeds at the high-temperature portion H to form metal oxide particles. Releases oxygen.

The reduced metal oxide particles are sent to the hydrothermal decomposition reactor 4 through the

upper communication ports

6a and 6b by the internal circulation flow. The temperature of the metal oxide particles decreases while flowing in the hydrothermal decomposition reactor 4, and as a result, the fluidized bed 2 in the hydrothermal decomposition reactor 4 has a temperature of 1400 ° C or less, preferably 1200 ° C or less. More preferably, a low temperature portion L of 1000 ° C. or lower is formed. The hydrothermal decomposition reaction proceeds in the low temperature portion L, and the metal oxide particles reduced by the thermal reduction reaction become the original metal oxide even when oxidized, and hydrogen is generated at the same time.

As described above, the hydrothermal decomposition apparatus using the inner circulation fluidized bed of the present embodiment includes the reactor 1 that contains the fluidized bed 2 made of metal oxide particles, and the fluid that is contained in the reactor 1. The solar light collecting means for condensing and irradiating sunlight S to the layer 2 is provided, and the reactor 1 includes a thermal reduction reactor 3 that performs a thermal reduction reaction, and a hydrothermal decomposition reactor that performs a hydrothermal decomposition reaction. 4, a dispersion plate 8 as low oxygen partial pressure gas introduction means for introducing a low oxygen partial pressure gas into the thermal reduction reactor 3 from below, and steam introduction for introducing water vapor into the hydrothermal decomposition reactor 4 from below Dispersion plate 9 as means, oxygen recovery means for recovering gas containing oxygen generated from thermal reduction reactor 3, and hydrogen recovery for recovering gas containing hydrogen generated from hydrothermal decomposition reactor 4 Means, and the inside of the thermal reduction reactor 3 and the inside of the hydrothermal decomposition reactor 4 The

upper communication ports

6a and 6b and the

lower communication ports

7a and 7b communicate with each other, and the

upper communication ports

6a and 6b and the

lower communication ports

7a and 7b are buried in the fluidized bed 2 and the upper communication ports The fluidized bed 2 is configured to flow between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 through the

ports

6a and 6b and the

lower communication ports

7a and 7b. The solar light S is irradiated to the upper surface of the fluidized bed 2 accommodated in the thermal reduction reactor 3.

Further, a screw conveyor 21 as a conveying means for conveying the fluidized bed 2 between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 to the

upper communication ports

6a and 6b and the lower communication ports 7a and 7b. , 22 is provided.

Further, the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 are configured separately from each other.

According to the hydrothermal decomposition apparatus and hydrothermal decomposition method using the inner circulating fluidized bed of the present embodiment described above, the fluidized bed 2 is formed as in the configuration of the first embodiment by installing the

screw conveyors

21 and 22. Therefore, it is not necessary to adjust the gas flow rate, and the metal oxide particles forming the fluidized bed 2 can be forcibly moved between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4. Further, the generated oxygen and hydrogen can be reliably separated and recovered by the gas sealing action by the metal oxide particles in the

screw conveyors

21 and 22.

Therefore, the following can be advantageously performed.
1 Oxygen and hydrogen are generated separately in the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4, respectively. Therefore, there is no need for gas separation of oxygen and hydrogen by a gas separator or the like as in the prior art. Improves purity.
2 In the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4, in order to advance the thermal reduction reaction and hydrothermal decomposition reaction, respectively, it becomes easy to arbitrarily control the reaction temperatures of two reactions having different reaction temperatures, Oxygen generation amount and hydrogen generation amount from each reactor are improved.
3 In the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4, the thermal reduction reaction and the hydrothermal decomposition reaction respectively proceed, so that it becomes easy to arbitrarily control the two reaction times. The generation amount and the hydrogen generation amount are improved, and the generation concentrations of recovered oxygen and hydrogen are improved.
4 In the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4, since the thermal reduction reaction and the hydrothermal decomposition reaction proceed, respectively, it is easy to arbitrarily control the reaction time and reaction rate of each reaction. The reaction heat (heat release amount) generated in the generation reaction can be fully utilized for the endothermic reaction in oxygen generation, and the solar heat → hydrogen conversion efficiency is improved.
5 Since the collected sunlight can be widely irradiated in the vicinity of the upper surface of the fluidized bed in the thermal reduction reactor 3 without being blocked by the gas separator, it can contribute to the formation of a high temperature portion of 1400 ° C. or higher. It can be effectively used for heating metal oxide particles, and the utilization efficiency of solar energy is increased.
6 Condensed sunlight is widely irradiated in the vicinity of the upper surface of the fluidized bed in the thermal reduction reactor 3 without being blocked by the gas separator, and can contribute to the formation of the high temperature portion H of 1400 ° C. or higher. The region of the high temperature part H can be expanded, and the amount of oxygen generated can be increased.
7 Since the size of the hydrothermal decomposition reactor 4 can be arbitrarily changed due to the structure of the reactor, the region of the low temperature portion L of 1400 ° C. or less formed in the hydrothermal decomposition reactor 4 can be expanded, Hydrogen production can be increased.
8 Due to the structure of the reactor, the metal oxide particles of the high temperature portion H formed near the upper surface of the fluidized bed in the thermal reduction reactor 3 have the upper communication port 6a positioned below the upper surface of the fluidized bed 2. Therefore, a part of the stagnation stays in the vicinity of the high temperature portion H and is heated to a higher temperature, so that the thermal reduction reaction is more likely to proceed and the amount of oxygen generated is improved.
9 Due to the structure of the reactor, the metal oxide particles in the high temperature part H formed in the vicinity of the upper surface of the fluidized bed 2 in the thermal reduction reactor 3 have the upper communication port 6a positioned below the upper surface of the fluidized bed 2 Therefore, a part of the stagnation stays around the high temperature part H, and the high-temperature sensible heat of 1400 ° C. or higher possessed by the metal oxide particles in the high temperature part H can be efficiently recovered and reused as exhaust heat.

This embodiment is a modification of the fifth embodiment. The same parts as those in the fifth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In this embodiment, as shown in FIG. 12, the outlets of the

screw conveyors

21 and 22 are reduced. That is, the opening amount of the upper communication port 6 b in the hydrothermal decomposition reactor 4 is smaller than the opening amount of the upper communication port 6 a in the thermal reduction reactor 3. Further, the opening amount of the lower communication port 7 a in the thermal reduction reactor 3 is smaller than the opening amount of the lower communication port 7 b in the hydrothermal decomposition reactor 4.

When the flow state of the fluidized bed 2 inside the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 changes, the gas in the thermal reduction reactor 3 and the gas in the hydrothermal decomposition reactor 4 are mixed. There is a case. In particular, when the flow rate of the gas is changed because the sun is hidden behind the clouds, the gas in the thermal reduction reactor 3 and the gas in the hydrothermal decomposition reactor 4 are mixed at startup, shutdown, and instantaneous power failure. There is a fear. In contrast, in this embodiment, the packing density of the metal oxide particles at the upper communication port 6b and the lower communication port 7a is increased by reducing the outlets of the

screw conveyors

21 and 22 as described above. Therefore, mixing of the gas in the thermal reduction reactor 3 and the gas in the hydrothermal decomposition reactor 4 can be drastically reduced. As a result, the hydrogen generation efficiency can be improved.

This embodiment is another modification of the fifth embodiment. The same parts as those in the fifth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In this embodiment, as shown in FIG. 13, a screw conveyor 27 for promoting the rise of metal oxide particles is arranged in the thermal reduction reactor 3.

In order to flow and raise the metal oxide particles in the thermal reduction reactor 3, it is necessary to supply a lot of low oxygen partial pressure gas such as nitrogen. In the present embodiment, the vertical movement of the screw conveyor 27 can promote the upward movement of the metal oxide particles. The screw conveyor 27 may be one axis, two axes, or multiple axes. According to the present embodiment, the supply amount of the low oxygen partial pressure gas supplied for increasing the metal oxide particles can be greatly reduced. For this reason, the apparatus which manufactures low oxygen partial pressure gas, such as nitrogen, can be reduced in size, and the operating cost of the apparatus which manufactures low oxygen partial pressure gas can be reduced. As a result, the cost of hydrogen production can be reduced.

In addition, you may combine the structure which reduces the exit of the

screw conveyors

21 and 22 like Example 6 in a present Example.

Still another embodiment will be described. In addition, the same code | symbol is attached | subjected to the same part as the said Examples 1 and 5, and description of the part is abbreviate | omitted.

In FIG. 14 which shows the hydrothermal decomposition apparatus using the internal circulation fluidized bed of a present Example, inside the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4, the inside of the thermal reduction reactor 3 and hydrothermal decomposition reaction are carried out.

Upper communication ports

6 a and 6 b communicating with the interior of the reactor 4 are formed, respectively, and the interior of the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 are provided below the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4.

Lower communication ports

7a and 7b communicating with each other are formed. Further, the

lower communication ports

7 a and 7 b are buried in the fluidized bed 2.

Between the upper communication port 6a and the lower communication port 7b, a belt conveyor 25 is provided, and the fluidized bed 2 is transported from the hydrothermal decomposition reactor 4 to the thermal reduction reactor 3. Further, a screw conveyor 26 is provided inside the thermal reduction reactor 3, and the fluidized bed 2 in the thermal reduction reactor 3 is connected to the other end side where the lower communication port 7a is provided from one end side where the upper communication port 6a is provided. It is comprised so that it may be conveyed toward. Further, the lower communication port 7 a of the thermal reduction reactor 3 communicates directly with the upper communication port 6 b of the water splitting reactor 4. The fluidized bed 2 can flow between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 through the

upper communication ports

6a and 6b and the

lower communication ports

7a and 7b.

dispersion plates

lower communication ports

7a and 7b so as not to disturb the flow of the fluidized bed 2 at the lower communication port 7. The surface of the dispersion plate 8 is inclined with the lowest part 7a 'of the lower communication port 7a as the lowest part, and the dispersion plate 9 substantially coincides with the height of the lowermost part 7b' of the lower communication port 7b. .

In the above configuration, a low oxygen partial pressure gas is introduced from the dispersion plate 8 to the thermal reduction reactor 3, and at the same time, water vapor is introduced from the dispersion plate 9 to the hydrothermal decomposition reactor 4. Then, the belt conveyor 25 and the screw conveyor 26 are driven to transport the fluidized bed 2 from the thermal reduction reactor 3 to the hydrothermal decomposition reactor 4 through the lower communication port 7a and the upper communication port 6b, and the lower communication port 7b The fluidized bed 2 is circulated between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 by transporting the fluidized bed 2 from the hydrothermal decomposition reactor 4 to the thermal reduction reactor 3 through the upper communication port 6a. That is, an internal circulation flow is generated through the

upper communication ports

6a and 6b and the

lower communication ports

7a and 7b.

The reduced metal oxide particles are sent to the hydrothermal decomposition reactor 4 through the lower communication port 7a and the upper communication port 6b. The temperature of the metal oxide particles decreases while flowing in the hydrothermal decomposition reactor 4, and as a result, the fluidized bed 2 in the hydrothermal decomposition reactor 4 has a temperature of 1400 ° C or less, preferably 1200 ° C or less. More preferably, a low temperature portion L of 1000 ° C. or lower is formed. The hydrothermal decomposition reaction proceeds in the low temperature portion L, and the metal oxide particles reduced by the thermal reduction reaction become the original metal oxide even when oxidized, and hydrogen is generated at the same time.

In the above configuration, the fluidized bed 2 can be moved in the thermal reduction reactor 3 by introducing a low oxygen partial pressure gas from the inclined dispersion plate 8, and the screw conveyor 26 can be omitted. Further, the fluidized bed 2 may be moved by applying vibration to the thermal reduction reactor 3, and introduction of the low oxygen partial pressure gas from the inclined dispersion plate 8 may be omitted.

As described above, the hydrothermal decomposition apparatus using the inner circulation fluidized bed of the present embodiment includes the reactor 1 that contains the fluidized bed 2 made of metal oxide particles, and the fluid that is contained in the reactor 1. The solar light collecting means for condensing and irradiating sunlight S to the layer 2 is provided, and the reactor 1 includes a thermal reduction reactor 3 that performs a thermal reduction reaction, and a hydrothermal decomposition reactor that performs a hydrothermal decomposition reaction. 4, a dispersion plate 8 as low oxygen partial pressure gas introduction means for introducing a low oxygen partial pressure gas into the thermal reduction reactor 3 from below, and steam introduction for introducing water vapor into the hydrothermal decomposition reactor 4 from below Dispersion plate 9 as means, oxygen recovery means for recovering gas containing oxygen generated from thermal reduction reactor 3, and hydrogen recovery for recovering gas containing hydrogen generated from hydrothermal decomposition reactor 4 Means, and the inside of the thermal reduction reactor 3 and the inside of the hydrothermal decomposition reactor 4 Is communicated with the

upper communication ports

6a and 6b and the

lower communication ports

7a and 7b. The

lower communication ports

7a and 7b are buried in the fluidized bed 2 so as to communicate with the

upper communication ports

6a and 6b and the lower communication ports. The fluidized bed 2 is configured to flow between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 through the

ports

7a and 7b, and is accommodated in the thermal reduction reactor 3 by the sunlight collecting means. It is comprised so that sunlight S may be irradiated to the upper surface of the said fluidized bed 2. As shown in FIG.

Further, a belt conveyor 25 as a conveying means for conveying the fluidized bed 2 between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 is provided at the upper communication port 6a and the lower communication port 7b. Is.

Further, the fluidized bed is formed between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4 between the upper communication port 6 a of the thermal reduction reactor 3 and the lower communication port 7 b of the hydrothermal decomposition reactor 4. A belt conveyor 25 is provided as a transport means for transporting 2, and the lower communication port 7 a of the thermal reduction reactor 3 and the upper communication port 6 b of the hydrothermal decomposition reactor 4 are in direct communication. .

Also, a screw conveyor 26 is provided as a moving means for moving the fluidized bed 2 in the thermal reduction reactor 3 inside the thermal reduction reactor 3.

According to the hydrothermal decomposition apparatus and hydrothermal decomposition method using the inner circulating fluidized bed of the present embodiment as described above, by installing the belt conveyor 25 or the screw conveyor 26 in addition to this, the configuration of the first embodiment is obtained. Therefore, it is not necessary to adjust the gas flow rate to form the fluidized bed 2, and the metal oxide particles forming the fluidized bed 2 are forcibly moved between the thermal reduction reactor 3 and the hydrothermal decomposition reactor 4. It becomes possible.

This embodiment is a modification of the eighth embodiment. The same portions as those in the eighth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In FIG. 15 which shows the hydrothermal decomposition apparatus using the internal circulation fluidized bed of the present embodiment, the metal oxide particles are held in a storage tank 28 connected to the thermal reduction reactor 3 and are contained in the thermal reduction reactor 3. It is transported and moved by the screw conveyor 29. Further, a screw conveyor 26 is disposed in order to cause the metal oxide particles to flow in the thermal reduction reactor 3. The screw conveyor 26 may be arranged in the vertical direction and the tanning direction in addition to the horizontal direction. In this embodiment, three screw conveyors 26 are arranged in the horizontal direction, the vertical direction, and the tanning direction.

In addition, a screw conveyor 30 is arranged to flow the metal oxide particles in the hydrothermal decomposition reactor 4. The screw conveyor 30 is not limited to the configuration arranged in the vertical direction as in the present embodiment, but may be arranged in the horizontal direction and the licking direction. A storage tank 31 for storing the metal oxide particles after the hydrothermal decomposition reaction is provided at the lower part of the hydrothermal decomposition reactor 4. A screw conveyor 32 for moving and transporting the metal oxide particles from the hydrothermal decomposition reactor 4 to the storage tank 31 is disposed.

Also, a belt conveyor 25 is provided between the storage tank 31 and the storage tank 28 for moving and transporting the metal oxide particles after the hydrothermal decomposition reaction.

According to the present embodiment, the

storage tanks

28 and 31 are provided, whereby the metal oxide particles after the hydrothermal decomposition reaction can be temporarily stored. For this reason, the metal oxide particles can be moved by the belt conveyor 25 at night.

It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made.

For example, the shape of the thermal reduction reactor or hydrothermal decomposition reactor is not limited to a vertically long rectangular parallelepiped, but also a horizontally long rectangular parallelepiped, a cube, a vertically long cylindrical shape, a horizontally long cylindrical shape, a vertically long elliptical cylinder, or a horizontally long elliptical cylindrical shape. Good. Further, the bottom shape of the thermal reduction reactor or hydrothermal decomposition reactor may be horizontal or inclined. In addition to moving the metal oxide particles, a screw conveyor or a belt conveyor, a container such as a bucket, or vibration generated by applying an external force may be used.

DESCRIPTION OF SYMBOLS 1 Reactor 2 Fluidized bed 3 Thermal reduction reactor 4 Hydrothermal decomposition reactor 5

Partition plates

6, 6a, 6b

Upper communication port

7, 7a, 7b Lower communication port 8 Dispersion plate (low oxygen partial pressure gas introduction means)
9 Dispersion plate (water vapor introduction means)
10 Introduction pipe (low oxygen partial pressure gas introduction means)
11 Introduction pipe (water vapor introduction means)
12 Enlarged part
13 windows
14 Outlet (oxygen recovery means)
15 Outlet (hydrogen recovery means)
21, 22 Screw conveyor (transportation means)
25 Belt conveyor (transportation means)
26 Screw conveyor (moving means)
201 Ground reflector
202 Tower reflector (sunlight collecting means)
S sunlight

Claims

A reactor containing a fluidized bed made of metal oxide particles, and a sunlight collecting means for collecting and irradiating sunlight onto the fluidized bed contained in the reactor,
The reactor includes a thermal reduction reactor that performs a thermal reduction reaction, a hydrothermal decomposition reactor that performs a hydrothermal decomposition reaction, and a low oxygen partial pressure gas that introduces a low oxygen partial pressure gas into the thermal reduction reactor from below. From the introduction means, the steam introduction means for introducing the steam into the hydrothermal decomposition reactor from below, the oxygen recovery means for recovering the gas containing oxygen generated from the thermal reduction reactor, and the hydrothermal decomposition reactor A hydrogen recovery means for recovering the gas containing the generated hydrogen,
The inside of the thermal reduction reactor and the inside of the hydrothermal decomposition reactor communicate with each other through an upper communication port and a lower communication port,
The lower communication port is buried in the fluidized bed so that the fluidized bed can flow between the thermal reduction reactor and the hydrothermal decomposition reactor through the upper communication port and the lower communication port. And
A hydrothermal decomposition apparatus using an internal circulation fluidized bed, wherein sunlight is applied to the upper surface of the fluidized bed accommodated in the thermal reduction reactor by the sunlight condensing means.
The thermal reduction reactor and the hydrothermal decomposition reactor are partitioned by a partition plate, and the interior of the thermal reduction reactor and the interior of the hydrothermal decomposition reactor are formed in an upper communication port and a lower portion formed in the partition plate. It communicates directly through the communication port,
The upper communication port and the lower communication port are buried in the fluidized bed, and directly between the thermal reduction reactor and the hydrothermal decomposition reactor through the upper communication port and the lower communication port. 2. The hydrothermal decomposition apparatus using an internal circulation fluidized bed according to claim 1, wherein the fluidized bed is configured to flow.
The internal circulation according to claim 1, wherein a transport means for transporting the fluidized bed is provided between the thermal reduction reactor and the hydrothermal decomposition reactor at the upper communication port and the lower communication port. Hydrothermal decomposition equipment using fluidized bed.
An enlarged portion that expands the horizontal cross-sectional area of the thermal reduction reactor upward is formed in the upper portion of the thermal reduction reactor, and a quartz window through which sunlight passes is provided in the upper portion of the enlarged portion. The hydrothermal decomposition apparatus using the inner circulating fluidized bed according to any one of claims 1 to 3, wherein
4. The hydrothermal decomposition apparatus using an inner circulation fluidized bed according to claim 3, wherein the thermal reduction reactor and the hydrothermal decomposition reactor are configured separately from each other.
A transport means for transporting the fluidized bed between the thermal reduction reactor and the hydrothermal decomposition reactor is provided between the upper communication port of the thermal reduction reactor and the lower communication port of the hydrothermal decomposition reactor. The hydrothermal decomposition apparatus using an inner circulating fluidized bed according to claim 1, wherein the lower communication port of the thermal reduction reactor and the upper communication port of the hydrothermal decomposition reactor are in direct communication with each other. .
The hydrothermal decomposition apparatus using an inner circulating fluidized bed according to claim 6, wherein a moving means for moving the fluidized bed in the thermal reduction reactor is provided inside the thermal reduction reactor.
A hydrothermal decomposition apparatus using the internal circulation fluidized bed according to any one of claims 1 to 7, wherein the fluidized bed is caused to flow in an internal circulation between the thermal reduction reactor and the hydrothermal decomposition reactor. However, an oxygen generation reaction in which a part of the fluidized bed is heated by sunlight in a low oxygen partial pressure gas atmosphere to release oxygen from the metal oxide, and water vapor is brought into contact with the metal oxide after the oxygen is released. A hydrothermal decomposition method using an internal circulating fluidized bed characterized in that two reactions of a hydrogen generation reaction for generating hydrogen proceed simultaneously.
The hydrothermal decomposition method using an internal circulation fluidized bed according to claim 8, wherein the oxygen generation reaction is allowed to proceed at 1400 ° C or higher and the hydrogen generation reaction is allowed to proceed at 1400 ° C or lower.
The hydrothermal decomposition method using an internal circulation fluidized bed according to claim 9, wherein the metal oxide is ferrite or zirconia supporting ferrite.
The zirconia is any of monoclinic zirconia, cubic zirconia, and tetragonal zirconia, and the cubic zirconia contains any one of yttria, calcia, and magnesia as a stabilizer. Hydrothermal decomposition method using the described internal circulation fluidized bed.
The hydrothermal decomposition method using an internal circulation fluidized bed according to claim 9, wherein the metal oxide is nickel ferrite or monoclinic zirconia supporting nickel ferrite.
The hydrothermal decomposition method using an internal circulation fluidized bed according to claim 9, wherein the metal oxide is cerium oxide or zirconia supporting cerium oxide.
The hydrothermal decomposition method using an internal circulation fluidized bed according to claim 12 or 13, wherein the metal oxide particles have a particle size of 100 to 750 µm.
The hydrothermal decomposition method using an internal circulation fluidized bed according to any one of claims 7 to 14, wherein the low oxygen partial pressure gas is nitrogen or argon.