JP2013194213A - Chemical looping combustion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical looping combustion system, capable of reducing non-reaction rate of char and enhancing the efficiency of the system without needing the enlargement of a volatile content reactor.SOLUTION: A chemical looping combustion system includes: a fuel reactor 2 in which a solid fuel 7 and a gasifying agent 19 are supplied to a reaction layer formed while supplying metal particles MeO4 to thermally decompose the solid fuel 7, and an oxidation reaction is performed while leaving generated char as it is; a volatile content reactor 3 in which a volatile content generated in the fuel reactor 2 is extracted and introduced to the reaction layer formed while supplying the metal particles MeO4 to perform the oxidation reaction of the volatile content; and an air reactor 1 in which Me5 reduced by the fuel reactor 2 is extracted from the fuel reactor 2 and made into the metal particles MeO4 through oxidation with air. The system is configured to circulate the metal particles 4, 5 through the volatile content reactor 3, the fuel reactor 2 and the air reactor 1.

Description

The present invention relates to a carbon dioxide (CO ₂ ) emission reduction technique that causes global warming, and more particularly to a technique for separating and recovering CO ₂ generated by burning fossil fuel used in fossil fuel boiler power generation. is there.

In recent years, CO ₂ emissions from large-scale thermal power generation facilities have become a problem as one of the causes of global warming, and technology for separating and collecting CO ₂ from combustion exhaust gas (CCS: Carbon dioxide Capture and Storage) ) Is attracting worldwide attention as an effective means for reducing CO ₂ emissions.

  CCS technologies applicable to boiler facilities that use fossil fuels include chemical absorption systems, oxyfuel combustion systems, and chemical looping combustion systems (CLC).

However, the chemical absorption system requires a lot of energy to regenerate the liquid adsorbed with CO ₂ , and the oxyfuel combustion system needs a lot of power to drive the oxygen production apparatus. In these CCS technologies, reduction of energy consumption is desired.

  On the other hand, since the CLC does not require liquid regeneration energy of the chemical absorption system or driving energy of the oxygen production apparatus in the oxygen combustion system, it can greatly reduce the energy consumption of the CCS technology and suppress the decrease in power generation efficiency. It has the feature that there is a possibility.

CLC oxidizes a fuel with metal oxide (MeO), which is an oxygen carrier, without directly contacting the air with the fuel, and the metal (Me) reduced by the oxidation reaction is oxidized with air to form a metal oxide. (MeO) is a technology for reuse. As a result, the reaction product becomes CO ₂ and moisture, and CO ₂ is easily recovered.

  FIG. 8 is a diagram for explaining the principle of the conventional CLC. As shown in the figure, the conventional CLC is composed of an air reactor 1 and a fuel reactor 2, and metal particles (MeO) 4 and metal particles (Me) 5 circulate and flow between them.

In the air reactor 1, the metal particles (Me) 5 react with oxygen in the air 6 to become metal oxide (MeO).
_{Me x O y-1 + 0.5O} 2 → Me x O y ··· (1)
Oxidized metal particles (MeO) 4 are separated from exhaust gas (N ₂ , O _2, etc.) 8 by a cyclone (not shown) and sent to the fuel reactor 2. In the fuel reactor 2, high-temperature metal particles (MeO) 4 and solid fuel (for example, coal) 7 come into contact with each other, and oxygen of the metal particles (MeO) 4 and the solid fuel 7 react. At this time, the metal particles (MeO) 4 obtained by oxidizing the solid fuel 7 are reduced to become metal particles (Me) 5 and form a circulation loop that returns to the air reactor 1 again.

_{(2n + m) Me x O} y + C n H 2m → (2n + m) Me x O y-1 + mH 2 O + nCO 2 ··· (2)
Exhaust gas 8 containing nitrogen and residual oxygen is discharged from the air reactor 1, and CO ₂ gas 9 and H ₂ O 10 (water vapor) are discharged from the fuel reactor 2. Since these gases are high temperature, heat is recovered by an exhaust heat recovery boiler (not shown) and used for power generation (see Non-Patent Document 1).

Currently, research and development are underway in universities, public research institutes, and private companies mainly in other countries, especially in Europe and North America. In the past, gas fuels such as methane and natural gas were the focus, but the target is shifting to solid fuels such as coal, which have a large CO ₂ reduction effect. For example, there are a 10 kWth bench device from Chalmers University, a 150 kWth bench device from Ohio State University, a 65 kWth bench device from Alstom, etc. (see Non-Patent Document 2).

  Coal, which is a solid fuel, is composed of components such as moisture, ash, volatiles, and fixed carbon. When coal is introduced into a high-temperature field of 800 ° C or higher, it is pyrolyzed and gas components (volatile matter + moisture) ) And solid components (fixed carbon + ash). In general, a gas component is called a volatile component, and a solid component is called a char.

FIG. 9 is a schematic system diagram showing a specific example of a conventional CLC.
As shown in the figure, the CLC includes an air reactor 1, a fuel reactor 2, a cyclone 12, an exhaust gas purification device 14, a heat exchanger 15, an air preheater 16, a heat exchanger 17, a CO ₂ purification device 18, and a CO _2. A compression liquefaction device 30 and a CO ₂ storage device 31 are provided. Between the air reactor 1, the cyclone 12, the fuel reactor 2, and the air reactor 1, the metal particles 4 and 5 are connected in an endless manner by pipes indicated by thick solid lines.

A solid fuel (for example, coal) 7 and a gasifying agent (for example, CO ₂ , H ₂ O) 19 are supplied to the fuel reactor 2. Inside the fuel reactor 2, a fluidized bed in which metal particles (MeO) 4 float and flow is formed. The metal particles (Me) 5 reduced in the fuel reactor 2 pass through the L valve 20 and are transferred to the air reactor 1.

Hot air 6 that has passed through the air preheater 16 is introduced into the air reactor 1, and inside the air reactor 1, the air 6 reacts with metal particles (Me) 5 to form metal particles (MeO). 4 is generated. The metal particles (MeO) 4 are moved to the cyclone 12 together with exhaust gas (N ₂ , residual O ₂ , NOx, fly ash, etc.) 8 and separated into solid metal particles (MeO) 4 and gaseous exhaust gas 8. .

The metal particles (MeO) 4 fall to the lower part of the cyclone 12 due to gravity, the flow rate is controlled by the L valve 20, and the metal particles (MeO) 4 move to the fuel reactor 2. CO ₂ gas 9 gas and H ₂ O (steam) 10 discharged from the fuel reactor 2 is cooled is sent to the heat exchanger 17, dehydrated and impurities in CO ₂ purification apparatus 18 is removed, further the CO ₂ The compressed liquefaction is performed in the CO ₂ compression liquefaction device 30, and the obtained liquefied CO ₂ is stored in the CO ₂ storage device 31.

On the other hand, the exhaust gas 8 such as N ₂ , residual O ₂ , NOx, fly ash and the like separated by the cyclone 12 is cooled by a heat exchanger 15, further heat-exchanged with air 6 by an air preheater 16, and finally exhaust gas. The system is made harmless by the purification device 14 and released to the atmosphere.

JP 2011-16873 A JP 2011-178572 A

Yoshida, Onosaki: Chemical looping combustion technology: Seasonal report Energy Research Institute, Vol. 33, No. 1, pp 29-35, 2010, 4 L.S.Fan: Chemical looping systems for fossil energy conversions: AIChE, 2010 Denchu Review No. 44 Toward the Realization of Coal Gasification Combined Cycle Power Generation-Support for Demonstration Machine Development and Future Research Development-

The prior art has not fully considered the difference between the two reaction rates of the volatile component of the gas component produced from coal and the char component of the solid component.
FIG. 10 is a diagram for explaining the problems of the prior art. As shown in the figure, when coal is thermally decomposed, volatile components of gas components and char of solid components are generated. Volatile components react rapidly with metal particles (MeO) in the order of a few seconds to produce CO ₂ gas and H ₂ O (water vapor). In contrast, char is generally less reactive and requires a reaction time on the order of several minutes.

Therefore, if one combustion reactor is designed based on the reaction rate of volatile matter, the char cannot secure the reaction time inside the combustion reactor, and the char is discharged without being reacted or unreacted. There is a problem that char accumulates in the reactor.
On the other hand, if one combustion reactor is designed on the basis of the reaction rate of char, the residence time of volatile components becomes longer, which increases the reaction volume and costs.

  The object of the present invention is to perform the oxidation reaction of the solid component (char) and the gas component (volatile component) in two towers, so that it is not necessary to enlarge the volume of the volatile reactor, and the unreacted rate of char It is an object of the present invention to provide a chemical looping combustion system that can reduce the amount of gas and increase the efficiency of the system.

In order to achieve the above object, the first means of the present invention comprises:
For example, a solid component generated by thermally decomposing the solid fuel by supplying a solid fuel and a gasifying agent to a reaction layer formed while supplying oxygen carrier particles of oxide such as metal particles (MeO) as described later A fuel reactor for performing an oxidation reaction in the reaction layer,
A volatile reactor that takes out a gas component generated in the fuel reactor and introduces it into a reaction layer formed while supplying oxygen carrier particles of an oxide to perform an oxidation reaction of the gas component;
For example, an air reactor is provided which takes out the oxygen carrier particles such as metal particles (Me) as described below, which are reduced by the fuel reactor, from the fuel reactor and oxidizes them with air to form oxide oxygen carrier particles. ,
The oxygen carrier particles are configured to circulate and flow through the volatile reactor, the fuel reactor, and the air reactor.

According to a second means of the present invention, in the first means,
The reaction layer formed in the fuel reactor is a moving layer in which the oxygen carrier particles move slowly and the gasifying agent flows through the gaps between the oxygen carrier particles.
The reaction layer formed in the volatile content reactor is a fluidized bed in which the oxygen carrier particles float and flow,
A gas component generated by the fuel reactor is used as a fluidizing gas for forming the fluidized bed.

According to a third means of the present invention, in the first means,
The gasification agent supplied to the fuel reactor is configured to use carbon dioxide and / or water vapor generated in the volatile content reactor.

The fourth means of the present invention is:
A volatile reactor that supplies a solid fuel and a gasifying agent to a reaction layer formed while supplying oxygen carrier particles of oxide to thermally decompose the solid fuel and oxidize the generated gas component;
A fuel reactor that takes out and introduces a part of the solid component and oxygen carrier particles generated in the volatile reactor, and performs an oxidation reaction of the solid component;
The oxygen carrier particles reduced by the fuel reactor are removed from the fuel reactor, and the air reactor is oxidized with air to form oxygen carrier particles of oxide,
The oxygen carrier particles are configured to circulate and flow through the volatile reactor, the fuel reactor, and the air reactor.

According to a fifth means of the present invention, in the fourth means,
Carbon dioxide and / or water vapor generated in the fuel reactor is discharged without being introduced into the volatile reactor.

According to a sixth means of the present invention, in the fifth means,
A heat exchanger is installed on the downstream side in the gas flow direction of the volatile content reactor, and carbon dioxide and / or steam generated in the fuel reactor and carbon dioxide and / or steam generated in the fuel reactor. Are both introduced into the heat exchanger.

A seventh means of the present invention is the first or fourth means,
The carrier fluid used for transporting the oxygen carrier particles by piping is configured to utilize carbon dioxide and / or water vapor generated by the oxidation reaction.

  The present invention is configured as described above, and it is necessary to enlarge the volume of the volatile reactor by performing the oxidation reaction of the solid component (char) and the gas component (volatile component) in two towers. Therefore, it is possible to provide a chemical looping combustion system in which the unreacted rate of char can be reduced and the efficiency of the system can be improved.

It is a schematic system diagram which shows the specific example of the chemical looping combustion system which concerns on Example 1 of this invention. It is a figure for demonstrating the principle of the chemical looping combustion system. It is a schematic diagram which shows the element test apparatus (a) implemented in order to grasp | ascertain the reaction time of a suitable char, and a test specification (b). It is a char unreacted rate characteristic figure which shows the result of the element test. It is a figure which shows an example of the heat balance of the CLC system which concerns on the present Example 1. FIG. It is a schematic system diagram which shows the specific example of the chemical looping combustion system which concerns on Example 2 of this invention. It is a schematic system diagram which shows the specific example of the chemical looping combustion system which concerns on Example 3 of this invention. It is a figure for demonstrating the principle of the conventional CLC. It is a schematic system diagram which shows the specific example of the conventional chemical looping combustion system. It is a figure for demonstrating the subject of a prior art.

  Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic system diagram showing a specific example of a chemical looping combustion system (CLC) according to Embodiment 1 of the present invention, and FIG. 2 is a diagram for explaining the principle of the CLC.
First, the principle of CLC according to the present embodiment will be described with reference to FIG.
The basic feature of the present invention is that the original combustion reactor is divided into two towers, a fuel reactor 2 and a volatile reactor 3, which are separately independent. Therefore, as shown in FIG. 2, the CLC is mainly composed of an air reactor 1, a fuel reactor 2, and a volatile content reactor 3. Between these, metal particles (MeO) 4 and metal particles (Me) 5 are formed. Is a system that circulates and flows.

  Inside the fuel reactor 2, high-temperature metal particles (MeO) 4 and metal particles (Me) 5 are mixed, and solid fuel (coal) 7 is supplied to the solid fuel (coal) 7. The solid component char is separated into the volatile component 13 of the gas component 11. The char reacts as it is inside the fuel reactor 2, and the volatile matter 13 that is a reaction inhibition factor of the char is sequentially sent to the volatile matter reactor 3 and is removed from the fuel reactor 2.

  As a preliminary experiment, the char gasification rate when the volatile matter was separated alone and the char gasification rate when the volatile matter was not separated were examined. It has been confirmed that the conversion rate has increased. This may be due to the effect of the gas partial pressure difference between the volatile matter and the char reaction product, or the volatile matter adsorbed on the reaction surface of the char. From this, it can be seen that the volatile matter is a factor that inhibits the reaction of char, and separation of the volatile matter and char is necessary for the efficient reaction of char.

On the other hand, in the air reactor 1, the metal particles (Me) 5 react with oxygen in the air 6 to be metal oxide (MeO) 4, and the generated metal particles (MeO) 4 are the cyclone 12 (see FIG. 1). Is separated from the exhaust gas (N ₂ , O ₂ ) 8 and sent to the volatile content reactor 3. The volatile matter 13 reacts by contacting with high-temperature metal particles (MeO) 4 to produce CO ₂ 9 and H ₂ O 10, which are discharged from the volatile reactor 3.

  By the oxidation of the solid fuel 7 in the fuel reactor 2, the metal particles (MeO) 4 are reduced to metal particles (Me) 5 and form a circulation loop that returns to the air reactor 1 again.

Next, the outline of CLC will be specifically described with reference to FIG.
As shown in the figure, the CLC includes an air reactor 1, a fuel reactor 2, a volatile content reactor 3, a cyclone 12, an exhaust gas purification device 14, a heat exchanger 15, an air preheater 16, a heat exchanger 17, and CO _2. The purification device 18, the CO ₂ compression liquefaction device 30, the CO ₂ storage device 31, and the like are provided, and are connected as shown in the figure.

  Between the air reactor 1, the cyclone 12, the volatile content reactor 3, the fuel reactor 2, and the air reactor 1, pipes shown by thick solid lines are endless so that the metal particles 4 and 5 can circulate. It is connected.

First, a solid fuel (for example, coal) 7 and a gasifying agent (for example, CO ₂ , H ₂ O) 19 are supplied to the fuel reactor 2. The fuel reactor 2 is formed with a moving bed (not shown) in which high-temperature metal particles (MeO) 4 and metal particles (Me) 5 are mixed. Here, the solid fuel (e.g., coal) 7 is thermally decomposed and separated into a solid component char and a gaseous component volatile matter 13, and the char remains in the fuel reactor 2 as it is and reacts to form a gaseous state. Volatile matter 13 moves to volatile reactor 3. Also, an appropriate amount of reduced metal particles (Me) 5 is discharged from the fuel reactor 2.

The discharged metal particles (Me) 5 pass through the L valve 20 which is a particle conveyance amount adjusting means and are transferred to the air reactor 1. High-temperature air 6 that has passed through the air preheater 16 is introduced into the air reactor 1, and inside the air reactor 1, the air 6 reacts with metal particles (Me) 5 to generate oxidized metal particles ( MeO) 4. The metal particles (MeO) 4 are moved to the cyclone 12 together with the exhaust gas (N ₂ , residual O ₂ , NOx, fly ash, etc.) 8, and are converted into solid metal particles (MeO) 4 and gaseous exhaust gas 8 due to the difference in specific gravity. To be separated.

The metal particles (MeO) 4 fall to the lower part of the cyclone 12 by gravity, pass through the L valve 20 which is a particle conveyance amount adjusting means, and move to the volatile content reactor 3. Inside the volatile content reactor 3, the volatile content 13 sent from the fuel reactor 2 reacts with the metal particles (MeO) 4 while the metal particles (MeO) 4 are suspended and flowed to react with CO ₂ gas and gas. H ₂ O (water vapor) is generated. Further, the metal particles (MeO) 4 are reduced by reaction with the volatile matter 13 to become metal particles (Me) 5, and the metal particles (Me) 5 and the unreacted metal particles (MeO) 4 are adjusted in the particle conveyance amount. It moves to the fuel reactor 2 through the L valve 20 as means.

Thus, in the CLC, the metal particles 4 and 5 react with the solid fuel 7 while circulating and flowing through the fuel reactor 2 → the air reactor 1 → the volatile content reactor 3 → the fuel reactor 2 →. Further, as a transporting fluid used for piping for transporting the metal particles 4 and 5 (portion shown by a thick solid line in FIG. 1), CO ₂ gas and / or H ₂ O (water vapor) generated in the system, or exhaust gas 8 is used. Is used.

The CO ₂ gas 9 and H ₂ O (steam) 10 produced in the volatile reactor 3 are sent to a heat exchanger 17 to be cooled, and the steam obtained by the heat exchanger 17 is sent to a power generation facility (not shown). It is done. Thereafter, the CO ₂ gas 9 and H ₂ O (water vapor) 10 are dehydrated and impurities are removed by the CO ₂ purification device 18, and the CO ₂ gas 9 is compressed and liquefied by the CO ₂ compression liquefaction device 30 to be liquefied. CO ₂ is stored in the CO ₂ storage device 31.

Exhaust gas 8 such as N ₂ , residual O ₂ , NOx, fly ash and the like separated by the cyclone 12 is cooled by a heat exchanger 15 and further heat exchanged with air 6 by an air preheater 16, and finally an exhaust gas purification device. 14 is detoxified and released to the atmosphere. The steam obtained by the heat exchanger 15 is sent to a power generation facility (not shown).

  As the metal particles (MeO) 4, for example, oxides such as nickel (Ni), iron (Fe), copper (Cu), and calcium (Ca) are used. In particular, iron oxide is suitable for CLC because it is pollution-free and inexpensive. The reduction and oxidation reaction formulas when iron oxide is used as the metal particles (MeO) 4 are shown below.

Reduction reaction: C (coal) + 6Fe ₂ O ₃ ⇒4Fe ₃ O ₄ + CO ₂ − endotherm (3)
Oxidation reaction: 4Fe ₃ O ₄ + O ₂ (air) ⇒ 6Fe ₂ O ₃ + exotherm (4)
When iron oxide is used as the metal particles (MeO) 4, the metal particles (MeO) 4 correspond to Fe ₂ O ₃ , and the metal particles (Me) 5 correspond to Fe ₃ O ₄ . In the air reactor 1, an oxidation reaction between Fe ₃ O ₄ and air represented by the above formula (4) occurs, and in the fuel reactor 2 and the volatile content reactor 3, the reduction reaction of Fe ₂ O ₃ represented by the above formula (3). Occurs.

The main components of the volatile matter 13 are CH ₄ , CO, and H ₂ , and in the volatile matter reactor 3, the following reaction occurs between the volatile matter 13 and Fe ₂ O ₃ that is metal particles (MeO) 4.

_{CH 4 + 6Fe 2 O 3 ⇒CO} + H 2 O + 4Fe 3 O 4 ··· (5)
CO + 3Fe ₂ O ₃ ⇒CO ₂ + 2Fe ₃ O ₄ (6)
H ₂ + 3Fe ₂ O ₃ ⇒H ₂ O + 2Fe ₃ O ₄ (7)
Next, the process leading to the present invention will be described. As described with reference to FIG. 10, when coal is thermally decomposed, volatile components of gas components and char of solid components are generated. Since the volatile component is a solid-gas reaction with metal particles (MeO), the reaction time is as fast as several seconds, while one char has a slow reaction completion time. Therefore, the reaction of char becomes a rate-limiting reaction, and a reactor design suitable for the reaction rate of char is required.

  Therefore, the present inventors conducted an element test in order to grasp an appropriate char reaction time. FIG. 3 is a schematic diagram showing the element test apparatus (a) and the test specification (b), and FIG. 4 is a char unreacted rate characteristic diagram showing the result of the element test.

In this element test apparatus, as shown in FIG. 3, a quartz sample container 51 (inner diameter 13 mm, outer diameter 16 mm, height 60 mm) is inserted into a quartz reaction tube 52 (inner diameter 17 mm, outer diameter 20 mm, height 1000 mm). The reaction tube 52 is installed in an electric furnace 53. A CO / O ₂ / CO ₂ monitor 55 is connected to the outlet side of the reaction tube 52.

In the element test, char 54 obtained by dry distillation of coal (Adalo charcoal) at 1000 ° C. is added to the sample container 51 with and without addition of Fe ₂ O ₃ which is metal particles (MeO) 4, and the reaction is performed. Each is inserted into a tube 52. Next, the reaction is performed at 1000 ° C. while CO ₂ gas is passed through the reaction tube 52 as the gasifying agent 9 (reaction gas).

C (Char) + CO ₂ ⇒ 2CO (8)
Then, the time-dependent change of the char reaction was determined from the CO gas concentration generated by this reaction and the residual char weight, and the relationship between the time and the unreacted rate of char was summarized in FIG. 4 according to the presence or absence of Fe ₂ O ₃ .
As is apparent from the test results of FIG. 4, the unreacted rate of char decreases with time, but the unreacted char is more when Fe ₂ O ₃ is added than when Fe ₂ O _{3 is} not added. The rate is extremely low. As a result, it became clear that Fe ₂ O ₃ is a factor for promoting the reaction.

  However, it was revealed that a reaction time of the order of minutes was required for the completion of the char reaction. In other words, it was confirmed that when a fuel reactor was designed based on a reaction rate on the order of several seconds of volatile matter, unreacted char was deposited in the reactor.

  The present invention divides the coal oxidation reaction into a char reaction and a volatile reaction, and reduces volatility separately from the fuel reactor 2 as shown in FIG. The fraction reactor 3 was provided, and the volatile matter 13 produced in the fuel reactor 2 was immediately sent to the volatile matter reactor 3 to be separated from char, and the char was left in the fuel reactor 2 as it was. Thus, by dividing the char reaction and the volatile reaction for each reactor, the volatile reactor 3 may be a reactor having a relatively small volume.

In this embodiment, in order to ensure the char residence time in the fuel reactor 2, the inside of the fuel reactor 2 is a moving bed. The moving layer is continuously supplied with metal particles, and slowly moves downward while filled with metal particles like an hourglass, and the gas (gasification agent 19) moves upward through the gaps between the particles. , Char slowly gasifies in its moving bed. Since the moving bed does not have a high gas flow rate unlike the bubble fluidized bed, the char does not scatter and adhere to the inner surface of the fuel reactor 2.
On the other hand, the volatile content reactor 3 is a fluidized bed, and the volatile content 13 generated from the fuel reactor 2 is used as a fluidizing gas, so that the volatile content 13 and the metal particles (MeO) 4 that are oxygen carriers are in good contact. To increase the reactivity.

Next, the design of each device will be described.
Since the air reactor 1 raises the introduced metal particles (Me) 5 by the air 6, the superficial velocity of the air 6 is 1.3 m / s (1000 ° C., particle size 150 μm). The cross-sectional area of the air reactor 1 is designed so as to be faster than the density of 5.15 g / cm ³ ).

In the fuel reactor 2, since the metal particles 4 and 5 form a moving bed, the flow rate of the gasifying agent 19 needs to be supplied at a speed slower than the fluidization start speed of the metal particles (MeO) 4 and 5. For example, when Fe ₂ O ₃ (particle size 150 μm, density 5.15 g / cm ³ ) is used, the fluidization start speed in a reactor at 1000 ° C. in a CO ₂ atmosphere is 0.015 m / s. The flow rate adjustment of the gasifying agent 19 and the cross-sectional area of the fuel reactor 2 are designed so that the superficial velocity of the reactor 2 is less than 0.015 m / s.

  The volatile content reactor 3 fluidizes the metal particles (MeO) 4 with the gas amount of the volatile content 13, so that the superficial velocity of the volatile content 13 is faster than the fluidization start speed 0.015 m / s. The cross-sectional area of the volatile reactor 3 is designed.

Moreover, although the reaction rate becomes faster as the temperature of each reactor 1, 2, 3 increases, the ash melts at 1100 ° C. or higher, and solidifies during cooling, and may become clogged. , 3 is preferably around 1000 ° C. In this example, as shown in the following Table 1, the temperature in each reactor 1, 2, 3 is maintained in the range of 800-1000 ° C.
Table 1 below shows the standard specifications for designing the reactors 1, 2, and 3.

FIG. 5 is a diagram illustrating an example of the heat balance of the CLC system according to the first embodiment.
In this example, 1000 ° C. metal particles (MeO) 4 exiting from the air reactor 1 are introduced into the volatile reactor 3. The volatile component 13 enters the volatile reactor 3 at 944 ° C., and after the fluidized bed reaction with the metal particles (MeO) 4, the metal particles (MeO) 4 and the CO ₂ gas 9 and H ₂ O (water vapor) which have reached 975 ° C. 10 is discharged from the volatile reactor 3.

  Metal particles (MeO) 4 at 975 ° C. enter the fuel reactor 2, cause a moving bed reaction with char, and volatile components 13 and metal particles (Me) 5 that have reached 944 ° C. due to endotherm are discharged from the fuel reactor 2. The The metal particles (Me) 5 at 944 ° C. enter the air reactor 1, undergo an oxidation reaction with the air 6, and the metal particles (MeO) 4 and the exhaust gas 8 that have reached 1000 ° C. are discharged from the air reactor 1. In such CLC, thermal equilibrium around 1000 ° C. can be maintained.

  Next, the L valve 20 will be described. In the present invention, the flow rate of the metal particles cannot be used with a mechanical valve because the movable part breaks down at 1000 ° C. Therefore, a pneumatic valve can be used, and examples of the pneumatic valve include an L valve, a J valve, and an N valve.

  The L valve is composed of a pipe with an L-shaped side surface. By performing aeration in the pipe, the metal particles in the pipe can be fluidized and transported and used as a circulating flow control valve for circulating fluidized beds. The In the L valve design, the pipe diameter is designed so that the superficial velocity of the aeration gas is 0.015 m / s, and the pressure loss of the vertical and horizontal pipes of the L valve is reduced. Design the length so that the vertical tube is larger.

  The flow control of the metal particles by the L valve is performed by supplying a control gas to the vertical pipe portion of the L valve. The flow rate of the control gas is not less than the particle fluidization start gas velocity, and the amount of movement of the metal particles, that is, the flow rate can be controlled by increasing or decreasing the control gas flow rate. The supply port for the control gas is provided at the bottom of the horizontal tube portion of the L valve and the vertical tube portion. In particular, the height of the supply port of the vertical pipe portion is generally recommended as an experience that is approximately twice the horizontal pipe portion diameter (D) from the horizontal pipe center height (H).

In the present embodiment, the solid fuel 7 is a solid fuel mainly composed of hydrocarbon such as coal, biomass, or a combination of coal and biomass.
For the gasifying agent 19, for example, CO ₂ gas or H ₂ O (water vapor) is used. When particles are transported by the gasifying agent 19, unnecessary piping is reduced and efficiency is increased.

In the exhaust gas purification device 14, the exhaust gas 8 may contain NOx, fly ash, finely pulverized metal particles, and the like, and a denitration device, a dust removal device, and the like may be provided as necessary.
The CO ₂ purification device 18 may contain moisture, ash, sulfur compounds, trace heavy metals, etc. in addition to CO _{2 in} the gas. If necessary, a dehydration device, a dust removal device, a desulfurization device, a heavy metal recovery device, etc. It can also be provided.

Next, the effect of the present embodiment will be described.
(1). By adopting a moving bed in the fuel reactor 2, the char residence time in the reactor can be secured on the order of minutes, so that the unreacted rate of char can be reduced and the CO ₂ recovery efficiency in CLC can be improved. Can do. Furthermore, when this system is used for a power generation system, power generation efficiency can be improved.

(2). Since the volatile component 13 can be immediately moved from the fuel reactor 2 to the volatile component reactor 3, it is possible to prevent the volatile component 13 from inhibiting the char reaction inside the fuel reactor 2.
(3). Since the volatile component 13 is diverted to the fluidized gas of the volatile reactor 3, the contact efficiency with the metal particles is high, which can contribute to the improvement of the reaction efficiency. Further, since no fluidizing gas is required from the outside, the volume of the volatile content reactor 3 can be reduced and the system can be made compact.

(4). Since there is no unreacted char and CO ₂ is not contained in the exhaust gas, it is possible to prevent a reduction in CO ₂ recovery efficiency.
As described above, in the problem of the rate-determination of char, by performing the oxidation reaction of char and volatile components in two towers, the unreacted rate of char can be reduced, and the efficiency of CLC can be improved.

FIG. 6 is a schematic system diagram showing a specific example of the chemical looping combustion system according to the second embodiment of the present invention.

In this embodiment, the difference from the first embodiment shown in FIG. 1 is that, as shown in FIG. 6, CO ₂ extending from the exhaust line between the volatile content reactor 3 and the heat exchanger 17 to the fuel reactor _2. A return line 32 is provided, and a valve 21 and a flow meter 22 are provided on the CO ₂ return line 32 to gasify the high-temperature CO ₂ gas 9 and H ₂ O (water vapor) 10 discharged from the volatile reactor 3. This is the point used as the agent 19.

Usually, in order to prevent the fuel reactor 2 from cooling, it is necessary to heat the gasifying agent 19 to about 400 to 1000 ° C., which causes a problem that energy consumption is large. In this embodiment, since the temperature of the CO ₂ gas 9 and H ₂ O (water vapor) 10 discharged from the volatile reactor 3 is about 1000 ° C. (see FIG. 5), it is used as it is as the gasifying agent 19. Therefore, heating is not necessary, and energy consumption can be reduced.

FIG. 7 is a schematic system diagram showing a specific example of the chemical looping combustion system according to the third embodiment of the present invention.
In the present embodiment, the difference from the first embodiment shown in FIG.
(1). Metal particles (MeO) 4 oxidized in the air reactor 1 are supplied independently to the fuel reactor 2 and the volatile content reactor 3, respectively.
(2). The solid fuel 7 and the gasifying agent 19 (CO ₂ , H ₂ O) are supplied to the volatile reactor 3 without being supplied to the fuel reactor 2,
(3). A solid component / metal particle transport pipe 27 for extracting both the solid component (char) 25 and the metal particles (Me) 26 generated in the volatile reactor 3 and transporting them to the fuel reactor 2 is provided.
(4). The CO ₂ gas 23 and H ₂ O (water vapor) 24 generated by the oxidation of the solid component (char) 25 in the fuel reactor 2 are not passed through the volatile reactor 3, and the CO generated in the volatile reactor 3 _This is the point that a bypass pipe 28 that is fed into the heat exchanger 17 together with the _two gases 9 and H ₂ O (water vapor) 10 is provided.

Metal particles (MeO) 4 oxidized in the air reactor 1 are independently supplied to the fuel reactor 2 and the volatile content reactor 3 by the L valve 20. The solid fuel 7 and the gasifying agent 19 (CO ₂ , H ₂ O) are supplied to the volatile content reactor 3 without being supplied to the fuel reactor 2. The solid fuel 7 is immediately decomposed into char and volatile matter inside the volatile reactor 3, the metal particles (MeO) 4 are reduced to metal particles (Me) 26, and the char 25 and metal particles (Me) 26 are solid. It moves to the fuel reactor 2 through the component / metal particle transport pipe 27.

Metal particles (MeO) 4 are supplied into the fuel reactor 2 to form a moving bed, and in the volatile content reactor 3, a fluidized bed is formed. Here, the char 25 and the metal particles (MeO) 4 react with each other, and the CO ₂ gas 23 and H ₂ O (water vapor) 24 produced thereby pass directly through the bypass pipe 28 without passing through the volatile reactor 3. It is sent to the heat exchanger 17.

Since coal is not supplied in the fuel reactor 2, only char reacts with the metal particles (MeO) 4 and produces only CO ₂ gas 9 and H ₂ O (water vapor) 10. For this reason, since no volatile matter is generated, the amount of gas transferred from the fuel reactor 2 to the volatile matter reactor 3 is reduced, and the cost can be reduced by making the volatile matter reactor 3 compact and reducing the diameter of the piping. I can plan.

  In this way, the amount of gas transferred to the volatile reactor 3 is reduced, and the volatile reactor 3 can be further reduced in size and cost.

1: air reactor,
2: Fuel reactor,
3: volatile reactor,
4: Metal particles (MeO),
5: Metal particles (Me),
6: Air,
7: Solid fuel,
9: CO ₂ gas,
10: H ₂ O (water vapor)
11: Gas component,
13: Volatile content,
17: heat exchanger,
19: Gasifying agent,
23: CO ₂ gas,
24: H ₂ O (water vapor),
25: Char,
26: Metal particles (Me),
27: Solid component / metal particle transport pipe,
28: Bypass pipe,
32: CO ₂ return pipe.

Claims (7)

A solid fuel and a gasifying agent are supplied to a reaction layer formed while supplying oxygen carrier particles of oxide to thermally decompose the solid fuel, and an oxidation reaction is performed in the reaction layer while leaving the generated solid component as it is. A fuel reactor;
A volatile reactor that takes out a gas component generated in the fuel reactor and introduces it into a reaction layer formed while supplying oxygen carrier particles of an oxide to perform an oxidation reaction of the gas component;
The oxygen carrier particles reduced by the fuel reactor are removed from the fuel reactor, and the air reactor is oxidized with air to form oxygen carrier particles of oxide,
A chemical looping combustion system configured to circulate and flow the oxygen carrier particles through the volatile content reactor, the fuel reactor, and the air reactor. The chemical looping combustion system of claim 1,
The reaction layer formed in the fuel reactor is a moving layer in which the oxygen carrier particles move slowly and the gasifying agent flows through the gaps between the oxygen carrier particles.
The reaction layer formed in the volatile content reactor is a fluidized bed in which the oxygen carrier particles float and flow,
A chemical looping combustion system configured to utilize a gas component generated in the fuel reactor as a fluidizing gas for forming the fluidized bed. The chemical looping combustion system of claim 1,
A chemical looping combustion system characterized in that carbon dioxide and / or water vapor generated in the volatile content reactor is used as a gasifying agent supplied to the fuel reactor. A volatile reactor that supplies a solid fuel and a gasifying agent to a reaction layer formed while supplying oxygen carrier particles of oxide to thermally decompose the solid fuel and oxidize the generated gas component;
A fuel reactor that takes out and introduces a part of the solid component and oxygen carrier particles generated in the volatile reactor, and performs an oxidation reaction of the solid component;
The oxygen carrier particles reduced by the fuel reactor are removed from the fuel reactor, and the air reactor is oxidized with air to form oxygen carrier particles of oxide,
A chemical looping combustion system configured to circulate and flow the oxygen carrier particles through the volatile content reactor, the fuel reactor, and the air reactor. The chemical looping combustion system of claim 4,
A chemical looping combustion system characterized in that carbon dioxide and / or water vapor generated in the fuel reactor is discharged without being introduced into the volatile content reactor. The chemical looping combustion system of claim 5,
A heat exchanger is installed on the downstream side in the gas flow direction of the volatile content reactor, and carbon dioxide and / or steam generated in the fuel reactor and carbon dioxide and / or steam generated in the fuel reactor. A chemical looping combustion system characterized in that both are introduced into the heat exchanger. The chemical looping combustion system according to claim 1 or 4,
A chemical looping combustion system characterized in that carbon dioxide and / or water vapor generated by the oxidation reaction is used as a transport fluid used for transporting the oxygen carrier particles by piping.

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