JP2015229603A - Chemical looping combustion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CLC (Chemical Looping Combustion) which makes it possible to change a COrecovery rate according to fluctuation in COdemand.SOLUTION: The CLC has a fuel reactor 2, a volatile component reactor 3, an air reactor 1, and COrecovery means 23. By adjusting the supply rate of a gasification agent 27 composed of COand moisture vapor to be supplied to the fuel reactor 2, a COrecovery rate in the COrecovery means 23 is controlled.

Description

The present invention relates to a technique for reducing carbon dioxide (hereinafter also abbreviated as CO ₂ ), which is a global warming problem, and more particularly, CO generated by burning fossil fuel used in fossil fuel boiler power generation and the like. _This relates to the _second separation and recovery technology.

In recent years, the consolidation of which is the main source of industrial CO ₂ refinery, CO ₂ seller is in search of new CO ₂ sources. Among them, CO ₂ discharged from a coal-fired power plant is attracting attention as a new supplier of industrial CO ₂ .

There are chemical absorption systems, oxyfuel combustion systems, chemical looping combustion systems (CLC) and the like as CO ₂ capture technologies applicable to boiler facilities using coal fuel.

In particular, CLC technology has recently attracted attention. CLC means that the fuel is oxidized with a metal oxide (MeO), which is an oxygen carrier, without directly contacting the air with the fuel, and the reduced metal (Me) is oxidized with the air and again becomes a metal oxide (MeO). ). After all, the reaction products in this system are CO ₂ and moisture, which is a technology that facilitates the recovery of CO ₂ .
The feature of CLC is that liquid regeneration energy in the chemical absorption system and driving energy of the oxygen production system in the oxygen combustion system are unnecessary, so energy consumption is greatly reduced compared to these technologies, and reduction in power generation efficiency is suppressed. There is a possibility.

FIG. 4 is a diagram for explaining the principle of a general two-column CLC. The CLC is composed of an air reactor 1 and a fuel reactor 2 as shown in the figure, and is a system in which metal particles (MeO) 4 and metal particles (Me) 5 circulate between them.
In the air reactor 1, the metal particles (Me) 5 react with oxygen in the air 6 to become metal particles (MeO) 4.

_{Me x O y-1 + 0.5O} 2 → Me x O y (1)
The oxidized metal particles (MeO) 4 are separated from the post-reaction gas 36 such as N ₂ or O ₂ by a cyclone (not shown) and sent to the fuel reactor 2.
In the fuel reactor 2, high-temperature metal particles (MeO) 4 and a 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 returning to the air reactor 1.

(2n + m) Me _x O _y + C _n H _2m →
(2n + m) Me _x O _y-1 + mH ₂ O + nCO ₂ (2)
A post-reaction gas 36 containing nitrogen and residual oxygen is released from the air reactor 1, and a CO ₂ gas 9 and H ₂ O (water vapor) 10 are discharged from the fuel reactor 2. Since these gases are high in temperature, heat is recovered by an exhaust heat recovery boiler (not shown) and used for power generation (see Non-Patent Document 1).
Coal, which is a fixed 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 thermally decomposed and gas components (water and volatiles). ) And solid components (fixed carbon and ash). In general, a gas component is called a volatile component, and a solid component is called a char.

  Examples of prior art related to the CLC system include Patent Documents 1 to 4 and Non-Patent Documents 1 and 2 as described below.

FIG. 5 is a conceptual diagram for explaining the basic configuration of the three-column CLC previously proposed by the present applicant (see Patent Document 4).
In this three-column CLC, the oxidation reaction of coal is divided into a char reaction and a volatile reaction, and the fuel reactor shown in FIG. The reactor 2 and the volatile reactor 3 are divided into two towers. The reason for this is to separate the volatile matter, which is a factor that inhibits the gasification reaction of char, and to efficiently advance the gasification reaction of char (see Non-Patent Document 2).

Accordingly, as shown in FIG. 5, the solid fuel (for example, coal) 7 is separated into a product gas 11 composed of char and volatile components of a solid component. The char (not shown) undergoes a gasification reaction inside the fuel reactor 2 as it is, and the volatile component-produced gas 11 which is a factor inhibiting the gasification reaction of the char is a volatile reaction disposed at the upper part of the fuel reactor 2. It moves to the reactor 3 sequentially and is excluded from the fuel reactor 2 inside.
FIG. 6 is a schematic system diagram showing a specific example of the three-column CLC.

As shown in the figure, the three-column CLC is mainly composed of three towers of an air reactor 1, a fuel reactor 2, and a volatile reactor 3, and includes a cyclone 13, a heat exchanger 15, and an air preheater. 16, a dust removal device 17, a heat exchanger 19, a denitration device 20, a dust removal device 21, a desulfurization device 22, a CO ₂ compression liquefaction device 23, an air blower 35, and the like are arranged and connected as shown in the figure.

  In this three-column CLC, metal particles (MeO) 4 and metal particles (Me) 5 can be circulated between the air reactor 1, the cyclone 13, the volatile reactor 3, the fuel reactor 2, and the air reactor 1. In addition, they are connected to L valves 24, 25, and 26, which are types of pneumatic valves having a gas seal function, in a loop shape by piping.

JP 2011-016873 A JP 2011-178572 A US Pat. No. 7,767,191 JP 2013-194213 A

Yoshida, Onosaki: Chemical Looping Combustion Technology Quarterly Research Institute of Advanced Energy, Vol. 1, pp29-35,2010,4 Hayashi: Development of next generation high efficiency coal gasification technology CCT Workshop 2009

Since domestic industrial CO ₂ is mainly used for welding seal gas and cooling dry ice, the demand for CO ₂ fluctuates depending on the manufacturing industry's economy and summer temperature. Therefore, when using CO ₂ discharged from a coal-fired power plant, it is necessary to meet the demand for industrial CO ₂ .

However, in the conventional oxyfuel combustion method and CLC method that recover CO ₂ from a coal-fired power plant, it is necessary to change the coal input heat load in accordance with the change in the CO ₂ recovery rate. There is also a problem that changes.

Although it is possible to change the CO ₂ recovery rate in the chemical absorption method, since the steam in the system is used for the regeneration heat of the absorbing solution, there is a problem that the amount of power generation changes as in other technologies.

Thus, with the conventional CO ₂ recovery technology, it was not possible to change the CO ₂ recovery rate in accordance with fluctuations in demand for industrial CO ₂ . Patent Document 4 does not disclose a technique for changing the CO ₂ recovery rate in accordance with fluctuations in the CO ₂ demand.

The object of the present invention is to provide a chemical looping combustion system capable of changing the CO ₂ recovery rate in accordance with fluctuations in demand for CO ₂ for industrial use.

In order to achieve the above object, the first means of the present invention comprises:
A moving bed fuel reactor for gasifying solid fuel;
A fluidized bed volatile reactor that oxidizes gas components generated from the fuel reactor with metal particles;
A fluidized bed air reactor that oxidizes the metal particles reduced by oxidation of the gas component with air;
A cyclone for separating the metal particles and the gas component discharged from the air reactor;
Carbon dioxide recovery means such as a carbon dioxide compression liquefaction device for separating and recovering carbon dioxide discharged from the volatile content reactor,
The present invention is directed to a chemical looping combustion system in which the fuel reactor, the volatile content reactor, the air reactor, and the cyclone are connected in a loop with a pneumatic valve and piping so that the metal particles circulate. .
And the first means of the present invention is:
The carbon dioxide recovery rate is controlled by the carbon dioxide recovery means by adjusting the supply amount of carbon dioxide or water vapor supplied to the fuel reactor or a gasifying agent containing both carbon dioxide and water vapor as components. It is characterized by becoming.

According to a second means of the present invention, in the first means,
The solid fuel is, for example, a solid fuel containing coal such as coal alone or a combination of coal and plant-derived biomass,
The relationship between the ratio of the gasifying agent molar amount to the fixed carbon molar amount of the solid fuel (gasifying agent molar amount / fixed carbon molar amount) α and the gasification rate of char generated in the fuel reactor is obtained in advance. Leave
Adjusting the supply amount of the gasifying agent based on the relationship between the gasification rate of the char corresponding to the carbon dioxide recovery rate to be controlled and the (molar amount of gasifying agent / molar amount of fixed carbon) α. It is a feature.

A third means of the present invention is the first or second means,
The configuration for controlling the carbon dioxide recovery rate by adjusting the supply amount of the gasifying agent,
A gasifying agent supply pipe for supplying the gasifying agent to the fuel reactor;
A valve attached to the gasifying agent supply pipe;
Carbon dioxide recovery rate change instructing means for instructing the opening degree adjustment of the valve according to the carbon dioxide recovery rate is provided.

According to a fourth means of the present invention, in any one of the first to third means,
A part of the exhaust gas from the volatile content reactor is used as the gasifying agent supplied to the fuel reactor.
According to a fifth means of the present invention, in any one of the first to third means,
As a gasifying agent supplied to the fuel reactor, a part of carbon dioxide recovered by the carbon dioxide recovery means is used.

According to a sixth means of the present invention, in any one of the first to third means,
Gasification for supplying a part of water vapor generated by a heat exchanger provided on the exhaust gas outlet side of the volatile content reactor and / or a heat exchanger provided on the exhaust gas outlet side of the cyclone to the fuel reactor It is the structure used as an agent.

According to a seventh means of the present invention, in any one of the first to sixth means,
Carbon dioxide or water vapor or carbon dioxide for promoting fluidization of the metal particles in the volatile content reactor between the fuel reactor and the volatile content reactor provided on the fuel reactor. For example, an assistant gas supply means comprising an assistant gas supply pipe and a valve for supplying an assistant gas containing both water and water vapor as a component is provided.

The eighth means of the present invention is the seventh means,
A part of the gasifying agent supplied to the fuel reactor is supplied to the volatile reactor as the assistant gas.

According to a ninth means of the present invention, in the seventh means,
A part of the carbon dioxide recovered by the carbon dioxide recovery means is used as the assistant gas supplied to the volatile reactor.

According to a tenth means of the present invention, in the seventh means,
A part of water vapor generated by a heat exchanger provided on the exhaust gas outlet side of the volatile reactor or / and a heat exchanger provided on the exhaust gas outlet side of the cyclone is supplied to the volatile reactor. It is the structure used as assistant gas, It is characterized by the above-mentioned.

The present invention is configured as described above, and can provide a chemical looping combustion system capable of changing the CO ₂ recovery rate in accordance with fluctuations in the demand for CO ₂ for industrial use.

It is the schematic system diagram which showed the specific example of the chemical looping combustion system which concerns on Example 1 of this invention. It is the schematic system diagram which showed the specific example of the chemical looping combustion system which concerns on Example 2 of this invention. FIG. 5 is a characteristic diagram showing the relationship between the gasification rate of char and α, with the ratio of the molar amount of gasifying agent to the molar amount of fixed carbon (gasic agent molar amount / fixed carbon molar amount) α as a parameter. It is a figure for demonstrating the principle of general two-column CLC. It is a conceptual diagram for demonstrating the basic composition of 3 tower type CLC which the present applicant proposed previously. It is a schematic system diagram which shows the specific example of this 3 tower type CLC.

  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 according to Embodiment 1 of the present invention.
As shown in FIG. 1, the three-column CLC is mainly composed of three towers of an air reactor 1, a fuel reactor 2, and a volatile reactor 3, and includes a cyclone 13, a heat exchanger 15, and an air preheater. 16, a dust removal device 17, a heat exchanger 19, a denitration device 20, a dust removal device 21, a desulfurization device 22, a CO ₂ compression liquefaction device 23, an air blower 35, and the like are arranged and connected as shown in the figure.

  In this three-column CLC, metal particles (MeO) 4 and metal particles (Me) 5 can be circulated between the air reactor 1, the cyclone 13, the volatile reactor 3, the fuel reactor 2, and the air reactor 1. In addition, they are connected to L valves 24, 25, and 26, which are types of pneumatic valves having a gas seal function, in a loop shape by piping.

A moving bed (not shown) in which high-temperature metal particles (MeO) 4 and metal particles (Me) 5 are mixed is formed in the fuel reactor 2. Here, the solid fuel (for example, coal) 7 is thermally decomposed in a high temperature field of 800 ° C. or higher, and is separated into a solid component char 12 and a product gas 11 mainly composed of volatile components. The product gas 11 is an upper part of the fuel reactor 2. Immediately move to the volatile reactor 3 located in Further, from the fuel reactor 2, reduced metal particles (Me) 5 and the generated char 12 are discharged in an appropriate amount.
The discharged char 12 and metal particles (Me) 5 pass through the L valve 26 and are transferred to the air reactor 1. Hot air 30 that has passed through the air preheater 16 is introduced into the air reactor 1, and the air 30 burns the char 12 inside the air preheater 16.

At the same time, the air 30 reacts with the metal particles (Me) 5 to generate metal particles (MeO) 4. The metal particles (MeO) 4 are moved to the cyclone 13 together with the combustion exhaust gas (N ₂ , O ₂ , CO ₂ , fly ash, etc.) 8, and the solid metal particles (MeO) 4 and the gaseous combustion exhaust gas due to the difference in specific gravity. 8 is separated.

The metal particles (MeO) 4 fall to the lower part of the cyclone 13 by gravity, pass through the L valve 24, and move to the volatile reactor 3. The volatile matter 13 sent from the fuel reactor 2 reacts with the metal particles (MeO) 4 while floating and flowing the metal particles (MeO) 4 in the volatile reactor 3. As a result, CO ₂ gas and H ₂ O (water vapor) are generated.

  The metal particles (MeO) 4 are reduced by reaction with the product gas 11 to become metal particles (Me) 5, and the metal particles (Me) 5 and unreacted metal particles (MeO) 4 pass through the L valve 25. Then, it moves to the fuel reactor 2.

Thus, in the CLC, the metal particles 4 and 5 react with the solid fuel (for example, coal) 7 while circulating and flowing through the fuel reactor 2 → the air reactor 1 → the volatile reactor 3 → the fuel reactor 2 →. To do. CO ₂ gas, H ₂ O (water vapor) or N ₂ generated in the system is used as the metal particle carrier gas 28 and 29 used for the L valves 24, 25 and 26 that carry the metal particles 4 and 5. .

The CO ₂ gas 9 and H ₂ O (steam) 10 generated in the volatile reactor 3 are sent to a heat exchanger 19 to be cooled, and the steam obtained by the heat exchanger 19 is sent to a power generation facility (not shown). Then, CO ₂ gas 9 and _{H 2} O (steam) 10 denitrator 20, dust collector 21, removal of the desulfurization apparatus 22 dehydration and impurities through such is done, the compression of CO ₂ gas 9 with CO ₂ compressed liquefier 23 Recovery by liquefaction is performed.

  The combustion exhaust gas 8 separated by the cyclone 13 is cooled by a heat exchanger 15, further heat-exchanged with the air 6 by an air preheater 16, and finally fly ash is removed by a dust removing device 17 and exhausted 18 into the atmosphere. Is done.

  The steam obtained by the heat exchanger 15 is sent to a power generation facility (not shown). The hot air 30 heated by the air preheater 16 is pressurized by the air blower 35, the flow rate is adjusted by the valve 33, and supplied from the lower part of the air reactor 1. A water cooling wall 14 is installed on the inner peripheral portion of the air reactor 1 to recover heat in the air reactor 1.

In the three-column CLC of the present invention, a fluidized bed is formed in the fuel reactor 2 in order to ensure the residence time of the char 12 in the fuel reactor 2. The metal particles (Me) 5 are continuously supplied, and like the hourglass, the metal particles (Me) 5 move slowly downward while being filled. On the other hand, the gasifying agents (CO ₂ , H ₂ O) 27 supplied from the lower part of the fuel reactor 2 move upward through the gaps of the moving metal particles (Me) 5, and the char 12 is in the moving bed. The gasification reaction occurs.

  On the other hand, the volatile content reactor 3 is a fluidized bed, and by making use of the product gas 11 generated in the fuel reactor 2 as a fluidizing gas, contact with the metal particles (MeO) 4 that are oxygen carriers is favorably performed. It has the effect of increasing reactivity.

Next, the CO ₂ recovery rate changing means that can be arbitrarily changed, which is a feature of the present invention, will be described in detail.
FIG. 3 is a characteristic diagram showing the relationship between the gasification rate of char and α, with the ratio of the molar amount of gasifying agent to the molar amount of fixed carbon (gas molar amount / fixed carbon molar amount) α as a parameter.
Fixed carbon is a solid carbon content excluding volatile matter, moisture and ash obtained by industrial analysis of coal. For example, when the gasification time (the time during which the char 12 stays in the fuel reactor 2) is designed to be 15 minutes, as shown in FIG. 3, when α = 1.2, the gasification rate is about 98%, and α = At 0.5, the gasification rate is 30%, and the gasification rate of char tends to decrease as α decreases.

Since the ratio α of the gasifying agent molar amount to the fixed carbon molar amount can be changed by the supply amount of the gasifying agent 27 (see FIG. 1), the gasification rate of the char 12 can be controlled. As a result, moving the unreacted char 12 to the air reactor 1 and burning it means that the amount of CO ₂ discharged from the volatile content reactor 3 is reduced by the amount of the unreacted char 12. . That is, a change in the supply amount of the gasifying agent 27 ⇒ a change in the gasification rate of the char 12 ⇒ a change in the production amount of the CO ₂ gas ⇒ a change in the CO ₂ recovery rate.

Further, since the unreacted char 12 burns in the air reactor 1, the amount of heat of the char 12 is recovered by the air reactor 1, so that the recovered heat of the entire system does not change.
As described above, the present invention is characterized in that the CO ₂ recovery rate is adjusted by controlling the supply amount of the gasifying agent 27 of the char 12.

Next, a method for changing the CO ₂ recovery rate will be described with reference to FIG.
As shown in FIG. 1, the high temperature mixed gas of CO ₂ gas 9 and H ₂ O (water vapor) 10 discharged from the volatile content reactor 3 is lowered in temperature by passing it through a heat exchanger 19. In order to use a part of this mixed gas as the gasifying agent 27, a gasifying agent supply pipe 40 extending from the outlet side of the heat exchanger 19 to the lower side of the fuel reactor 2 is provided. A circulation blower 34 and a valve 32 are provided on the way.

Further, the opening degree of the valve 32 is controlled by a CO ₂ recovery rate changing instruction means 31 constituted by, for example, a keyboard.
When changing the CO ₂ recovery rate in accordance with a change in demand for industrial CO ₂ , the desired CO ₂ recovery rate is first input to the CO ₂ recovery rate change instruction means 31. Based on this input, the opening degree of the valve 32 is adjusted, and the supply flow rate of the gasifying agent 27 sent by the circulation blower 34 is controlled.

Then, the unreacted char 12 moves to the air reactor 1 together with the metal particles (Me) 5. As a result, the amount of CO ₂ in the combustion exhaust gas 8 changes, and at the same time, the amount of CO ₂ gas 9 and H ₂ O (water vapor) 10 discharged from the volatile content reactor 3 also changes, and the desired CO ₂ recovery rate. Changed to

At the same time, since the gas temperature of the combustion exhaust gas 8 changes, the amount of water flowing to the heat exchanger 15 is changed so as to reach a predetermined gas temperature, and the exhaust gas sensible heat as steam is recovered. Similarly, since the temperature of the gas discharged from the volatile reactor 3 also changes, the amount of water flowing to the heat exchanger 19 is changed so as to reach a predetermined gas temperature, and exhaust gas sensible heat as steam is recovered. Thereby, even if the CO ₂ recovery rate is changed, the steam flow rate does not change.

In order to adjust the supply amount of the gasifying agent 27, the opening degree of the valve 32 is adjusted using the relationship between (gasifying agent molar amount / fixed carbon molar amount) α in FIG. .
For example, when the fuel reactor 2 is designed so that the char 12 stays for 15 minutes, in order to change the CO ₂ recovery rate from 98% to 30%, the gasification time 15 minutes from FIG. When the char gasification rate in 98 is changed from 98% to 30%, it is set to (amount of gasifying agent / amount of fixed carbon) α. In this case, α is changed from 1.2 to 0.5.

Therefore, the opening degree of the valve 32 is widened, and the supply amount of the gasifying agent 27 from the circulation blower 34 is increased so that the value of α is 0.5. As a result, 30% of the char is gasified and transferred to the volatile reactor 3 to be recovered as industrial CO ₂ , and the remaining unreacted char 12 is combusted in the air reactor 1.

As the gasifying agent, CO ₂ gas or H ₂ O (water vapor), or both CO ₂ gas and H ₂ O (water vapor) can be used. Further, CO ₂ gas or H ₂ O (water vapor), or both CO ₂ gas and H ₂ O (water vapor) can be supplied from a system different from the embodiment shown in FIG.

As a CO ₂ gas supply source, CO ₂ recovered by the CO ₂ compression liquefaction apparatus 23 shown in FIG. 1 may be reused.
Moreover, you may utilize the water vapor | steam produced | generated from the heat exchangers 15 and 19 shown in FIG.

Furthermore, when a mixed gas of CO ₂ gas and H ₂ O (water vapor) is used as the gasifying agent, a part of the mixed gas discharged from the volatile reactor 3 is circulated by the circulation blower 34 as in this embodiment. If it is used after recirculation, the running cost can be kept low.

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 / oxidation reaction formula when iron oxide is used as the metal particles (MeO) 4 is shown below.

Reduction reaction: C (for example, coal) + 6Fe ₂ O ₃ ⇒4Fe ₃ O ₄ + CO ₂ − endothermic (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 of Fe ₃ O ₄ represented by the above formula (4) occurs with air, 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 product gas 11 shown in FIG. 1 are CH ₄ , CO, and H _{2. In} the volatile content reactor 3, the following reaction occurs between the product gas 11 and Fe ₂ O ₃ that is metal particles (MeO) 4. Resulting 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)

  In general, in a circulating fluidized bed, a pneumatic valve such as a mechanical valve or an L valve is used as a gas seal valve for particle conveyance. For mechanical valves, a pneumatic valve such as an L valve is used because the seal portion is damaged at 600 ° C. or higher. The L valve is an L-shaped pipe, which is driven by aeration by fluidizing the particle layer and controlling the particle conveying flow rate.

  FIG. 2 is a schematic system diagram showing a specific example of the chemical looping combustion system according to the second embodiment of the present invention.

  When starting up the chemical looping combustion system or during low load operation, the amount of the product gas 11 from the fuel reactor 2 is small, and therefore the metal particles 4 and 5 in the volatile reactor 3 cannot be fluidized well. is there. If it does not fluidize, the metal particles 4 and 5 overflow into the L valve 25 and cannot move. Therefore, the metal particles 4 and 5 accumulate in the volatile reactor 3 and the pressure loss of the volatile reactor 3 increases.

When the particle layer pressure of the volatile reactor 3 becomes larger than the pressure of the L valve 25, gas sealing cannot be performed. As a result, there is a problem that the product gas 11 from the fuel reactor 2 flows from the L valve 25 and the circulation fluidization of the volatile content reactor 3 is stopped.
Further, since the metal particles (MeO) 4 are not stirred, the reactivity with the product gas 11 is lowered.

  As a countermeasure, in this embodiment, as shown in FIG. 2, fluidizing assist gas 37 is supplied between the fuel reactor 2 and the volatile content reactor 3, that is, in the lower part of the volatile content reactor 3. An assist gas supply pipe 41 is connected, and a valve 38 is attached to the assist gas supply pipe 41.

  When the predetermined amount of product gas 11 cannot be obtained from the fuel reactor 2 such as when the system is started up or during low load operation, the assist gas 37 for fluidization is supplied from the assist gas supply pipe 41. The fluidization of the metal particles 4 and 5 in the volatile content reactor 3 is promoted by the assist gas 37.

As the assist gas 37, CO ₂ gas, H ₂ O (water vapor), or a mixed gas of CO ₂ gas and H ₂ O (water vapor) can be used.
In this embodiment, as shown in FIG. 2, an assist gas supply pipe 41 is branched from between the circulation blower 34 on the gasifying agent supply pipe 40 and the valve 32 toward the lower part of the volatile reactor 3, and the assist gas A valve 38 is provided on the supply pipe 41, and an assist gas supply instructing means 42 composed of, for example, a keyboard is connected to the valve 38.

  When the predetermined amount of the produced gas 11 cannot be obtained from the fuel reactor 2, such as when the system is started up or during low load operation, the valve 38 is opened by an instruction from the assist gas supply instructing means 42, The assist gas 37 is supplied from the lower part of the volatile content reactor 3 to promote fluidization of the metal particles 4 and 5 in the volatile content reactor 3.

When fluidization of the metal particles 4 and 5 in the volatile reactor 3 is performed smoothly, the valve 38 is closed by an instruction from the assist gas supply instruction means 42.
If the CO ₂ gas or H ₂ O (water vapor) discharged from the volatile content reactor 3 is branched from the gasifying agent supply pipe 40 and supplied as the assist gas 37 as in this embodiment, the running cost can be kept low. be able to.

It is also possible to supply CO ₂ gas and H _{2 O} a (water vapor) from another system.
Further as the supply source of the CO ₂ gas, it may be reused a CO ₂ recovered by the CO ₂ compressor liquefier 23. Furthermore, water vapor generated from the heat exchangers 15 and 19 may be used as a source of H ₂ O (water vapor).

  If the assist gas 37 is used as in this embodiment, the metal particles 4 and 5 can move even when the chemical looping combustion system is started up or during low load operation, so that the pressure balance in the system can be maintained, and good circulation flow can be maintained. State is maintained.

In FIG. 2, for the sake of explanation, the CO ₂ recovery rate change instructing means 31 and the assist gas supply instructing means 42 are separately provided. In practice, however, the CO ₂ recovery rate is changed and the assist gas is supplied with one instruction means. Will be instructed.

  Other configurations and functions of the CLC in this embodiment are the same as those in the first embodiment shown in FIG.

Although the CO ₂ recovery rate in accordance with the demand for industrial CO ₂ can be achieved by the chemical absorption method, there is a problem that energy loss is large, the amount of steam fluctuates, and a stable power generation amount cannot be obtained.

On the other hand, the chemical looping combustion system of the present invention can arbitrarily select a CO ₂ recovery rate corresponding to the demand for industrial CO ₂ , and at this time, the heat obtained in the entire system is substantially the same. The feature is that the amount of steam is obtained and the amount of power generation does not decrease.

Moreover, the disposal method of a large amount of CO ₂ recovered from a coal-fired power plant has not been solved, and it is considered that practical application is difficult. On the other hand, it is expected to be acceptable at home and abroad as long as it is at the same level of CO ₂ generation as natural gas thermal power plants. By the CO ₂ recovery from coal-fired power plant from 100% to 50%, can be suppressed to a CO ₂ emission of natural gas-fired power plants comparable, the CO ₂ from the combustion exhaust gases in coal-fired power plants separation -It is fully compatible with carbon dioxide capture and storage (CCS) technology.

Furthermore, the present invention is applicable not only to industrial CO ₂ but also to the business CCS field.

  In the above embodiment, coal is used as the solid fuel. However, for example, a fixed fuel using both coal and plant-derived biomass is also applicable.

1: air reactor,
2: Fuel reactor,
3: volatile reactor,
4: Metal particles (MeO),
5: Metal particles (Me),
6: Air,
7: Solid fuel,
8: Combustion exhaust gas,
9: CO ₂ gas,
10: H ₂ O (water vapor),
11: generated gas,
12: Char,
13: Cyclone,
15, 19: heat exchanger,
23: CO ₂ compression liquefaction device,
24, 25, 26: L valve,
27: Gasifying agent,
30: Air,
31: CO ₂ recovery rate change instruction means,
32, 38: valve,
37: Assist gas,
40: Gasifying agent supply piping,
41: Assist gas supply piping,
42: Assist gas supply instruction means.

Claims (10)

A moving bed fuel reactor for gasifying solid fuel;
A fluidized bed volatile reactor that oxidizes gas components generated from the fuel reactor with metal particles;
A fluidized bed air reactor that oxidizes the metal particles reduced by oxidation of the gas component with air;
A cyclone for separating the metal particles and the gas component discharged from the air reactor;
Comprising carbon dioxide recovery means for separating and recovering carbon dioxide discharged from the volatile content reactor,
In the chemical looping combustion system in which the fuel reactor, the volatile content reactor, the air reactor, and the cyclone are connected in a loop with a pneumatic valve and piping so that the metal particles circulate,
The carbon dioxide recovery rate is controlled by the carbon dioxide recovery means by adjusting the supply amount of carbon dioxide or water vapor supplied to the fuel reactor or a gasifying agent containing both carbon dioxide and water vapor as components. A chemical looping combustion system characterized by The chemical looping combustion system of claim 1,
The solid fuel is a solid fuel containing coal,
The relationship between the ratio of the gasifying agent molar amount to the fixed carbon molar amount of the solid fuel (gasifying agent molar amount / fixed carbon molar amount) α and the gasification rate of char generated in the fuel reactor is obtained in advance. Leave
Adjusting the supply amount of the gasifying agent based on the relationship between the gasification rate of the char corresponding to the carbon dioxide recovery rate to be controlled and the (molar amount of gasifying agent / molar amount of fixed carbon) α. Characteristic chemical looping combustion system. The chemical looping combustion system according to claim 1 or 2,
The configuration for controlling the carbon dioxide recovery rate by adjusting the supply amount of the gasifying agent,
A gasifying agent supply pipe for supplying the gasifying agent to the fuel reactor;
A valve attached to the gasifying agent supply pipe;
A chemical looping combustion system comprising: a carbon dioxide recovery rate change instructing means for instructing an opening degree adjustment of the valve according to the carbon dioxide recovery rate. The chemical looping combustion system according to any one of claims 1 to 3,
A chemical looping combustion system characterized in that a part of exhaust gas from the volatile content reactor is used as a gasifying agent supplied to the fuel reactor. The chemical looping combustion system according to any one of claims 1 to 3,
A chemical looping combustion system characterized in that a part of carbon dioxide recovered by the carbon dioxide recovery means is used as a gasifying agent supplied to the fuel reactor. The chemical looping combustion system according to any one of claims 1 to 3,
Gasification for supplying a part of water vapor generated by a heat exchanger provided on the exhaust gas outlet side of the volatile content reactor and / or a heat exchanger provided on the exhaust gas outlet side of the cyclone to the fuel reactor A chemical looping combustion system, characterized in that it is configured to be used as an agent. The chemical looping combustion system according to any one of claims 1 to 6,
Carbon dioxide or water vapor or carbon dioxide for promoting fluidization of the metal particles in the volatile content reactor between the fuel reactor and the volatile content reactor provided on the fuel reactor. A chemical looping combustion system comprising an assistant gas supply means for supplying an assistant gas containing both water and water vapor as components. The chemical looping combustion system of claim 7,
A chemical looping combustion system, wherein a part of the gasifying agent supplied to the fuel reactor is supplied to the volatile reactor as the assistant gas. The chemical looping combustion system of claim 7,
A chemical looping combustion system characterized in that a part of the carbon dioxide recovered by the carbon dioxide recovery means is used as the assistant gas supplied to the volatile content reactor. The chemical looping combustion system of claim 7,
A part of water vapor generated by a heat exchanger provided on the exhaust gas outlet side of the volatile reactor or / and a heat exchanger provided on the exhaust gas outlet side of the cyclone is supplied to the volatile reactor. A chemical looping combustion system that is configured to be used as an assistant gas.