JP2022021242A - Solid carbon recovery type energy supply system, and, solid carbon recovery type energy supply method - Google Patents

Abstract

To provide a solid carbon recovery type energy supply system capable of easily immobilizing carbon dioxide.SOLUTION: A solid carbon recovery type energy supply system includes: reforming units 12A and 12B that have reforming spaces in which reforming catalysts are housed, and reform fuel gas including hydrocarbons with carbon dioxide in the reforming space to generate reforming gas including hydrogen and carbon monoxide; carbon precipitation portions 14A and 14B that are provided on the downstream side of the reforming units 12A and 12B and precipitate solid carbon from the reforming gas sent from the reforming units 12A and 12B; and a fuel cell stack 16 that is provided on the downstream side of the carbon precipitation portions 14A and 14B and consumes the reforming gas sent from the carbon precipitation portions 14A and 14B to obtain energy.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solid carbon recovery type energy supply system and a solid carbon recovery type energy supply method, in particular, using a hydrocarbon fuel to generate and utilize energy such as electricity and heat, and to generate carbon in carbon dioxide. The present invention relates to a solid carbon recovery type energy supply system and a solid carbon recovery type energy supply method for recovering as solid carbon.

When energy such as electricity and heat is obtained by a combustion reaction or an electrochemical reaction using a hydrocarbon fuel, carbon dioxide is generated during the energy obtaining reaction. When this carbon dioxide is emitted into the atmosphere, it causes global warming. Immobilization by press-fitting as liquefied carbon dioxide is required.
Therefore, conventionally, in order not to discharge carbon dioxide associated with a power generation reaction in a power generation system to the outside, carbon dioxide gas is separated and recovered from off-gas and exhaust gas after use (see Patent Document 1).

Patent No. 6692394 The 4th New Energy and Hydrogen Subcommittee Symposium of the Japan Energy Society Presentation material "CO2 resource recycling process pioneered by catalytic reaction engineering and normal temperature operation methanation technology" Shizuoka University Graduate School of Integrated Science and Technology Fukuhara Nagatoshi

However, in order to immobilize the recovered carbon dioxide gas in a carbon dioxide storage tank deep underground, the carbon dioxide recovered by gas can be compressed and liquefied, or a pipeline can be laid to reach the carbon dioxide storage tank site. It is necessary to transport or further compress at the storage tank site and press it into a storage tank several thousand meters underground, which consumes a large amount of energy in transporting and injecting the recovered carbon dioxide, and improving the transportation and press-fitting infrastructure. There is a problem that it takes a lot of time and effort.
In addition, when carbon dioxide is generated along with the above-mentioned energy consumption and emitted to the atmosphere, there is a problem that the net amount of carbon dioxide fixation decreases and the effectiveness as a measure against global warming decreases. ..

Furthermore, since the location and storage capacity of the above-mentioned carbon dioxide storage tank are limited by various conditions such as the condition of the stratum, the transportation distance to the storage site may be extended depending on the installation location of the power generation system or heat supply system, and press-fitting may be performed. There is a problem that the amount of carbon dioxide that can be immobilized is limited.
In order to immobilize or the like, a process such as liquefaction is required, which is troublesome.

Further, Non-Patent Document 2 describes that the production of syngas and the recovery of carbon are planned by dry reforming of methane. However, there is no description of how carbon is recovered in the energy supply system.

The present invention has been made in consideration of the above facts, and is a solid carbon recovery type energy supply system capable of easily recovering carbon dioxide as solid carbon when supplying energy using a hydrocarbon fuel. , And, an object of the present invention is to provide a solid carbon recovery type energy supply method.

The solid carbon recovery type energy supply system according to claim 1 has a reforming space in which a reforming catalyst is housed, and carbon dioxide reforms a fuel gas containing a hydrocarbon with carbon dioxide in the reforming space. A reforming section that generates a reforming gas containing hydrogen and carbon monoxide, and a carbon precipitation section that is provided on the downstream side of the reforming section and precipitates solid carbon from the reforming gas delivered from the reforming section. A gas consuming unit, which is provided on the downstream side of the carbon precipitation unit and consumes the reformed gas delivered from the carbon precipitation unit to obtain energy.

The solid carbon capture type energy supply system according to claim 1 includes a reforming unit and a carbon precipitation unit. The reforming section has a reforming space in which a reforming catalyst is housed, and the reforming gas containing hydrogen and carbon monoxide is reformed by carbon dioxide reforming the fuel gas containing hydrocarbons with carbon dioxide in the reforming space. To generate. The carbon precipitation section is provided on the downstream side of the reforming section, and solid carbon is precipitated from the reforming gas sent from the reforming section. By precipitating solid carbon in this way, carbon dioxide can be easily immobilized without being separately immobilized.

The reformed gas delivered from the carbon precipitation section is consumed by the gas consuming section provided on the downstream side of the carbon precipitation section to obtain energy.

The solid carbon capture type energy supply system according to claim 2 has a water separation unit that separates water from the reformed gas after use discharged from the gas consumption unit, and the post-use water separation unit in which water is separated by the water separation unit. It is provided with a gas circulation path for supplying the reformed gas to the reformed portion.

According to the solid carbon capture type energy supply system according to claim 2, carbon dioxide is discharged to the outside by supplying carbon dioxide in the reformed gas after use in which water is separated in the water separation section to the reforming section. It can be used as a raw material for carbon dioxide reforming.

The solid carbon recovery type energy supply system according to claim 3 is provided on the downstream side of the carbon precipitation section and on the upstream side of the gas consuming section, and the flow rate of the reformed gas delivered from the carbon precipitation section and the flow rate of the reformed gas are transmitted. It is provided with a carbon information output unit that measures at least one of the pressures and outputs the deposited carbon information regarding the amount of carbon deposited in the carbon precipitation unit.

In the solid carbon recovery type energy supply system according to claim 3, the carbon precipitated in the carbon precipitation section is measured by measuring at least one of the flow rate and the pressure of the reformed gas sent from the carbon precipitation section in the carbon information output section. Precipitated carbon information regarding the amount can be obtained. Based on this precipitated carbon information, the carbon precipitation portion can be exchanged and the flow of the reformed gas can be maintained. In addition, it is possible to prevent system stoppage and failure due to blockage of the reformed gas flow path.

The solid carbon recovery type energy supply system according to claim 4 is the modification of the plurality of carbon precipitation portions based on the plurality of the carbon precipitation portions and the precipitated carbon information output from the carbon information output unit. It is provided with a switching unit for switching the carbon precipitation unit, which is the destination of the reformed gas from the quality unit.

The solid carbon recovery type energy supply system according to claim 4 includes a plurality of the carbon precipitation portions, and is a reforming gas among the plurality of carbon precipitation portions based on the precipitated carbon information output from the carbon information output unit. The carbon depositing part, which is the destination of the carbon, is switched. As a result, it is possible to stop the supply of the reformed gas to the carbon precipitate portion having a large amount of deposited carbon and perform operations such as replacement.

In the solid carbon recovery type energy supply system according to claim 5, the gas consuming unit is a fuel cell stack that uses the reformed gas for a power generation reaction, and the fuel gas is supplied to the fuel electrode of the fuel cell stack. Will be done.

According to the solid carbon capture type energy supply system according to claim 5, power can be generated by a fuel cell using a reformed gas.

The solid carbon recovery type energy supply system according to claim 6 has a removing unit that removes at least one of hydrogen, carbon monoxide, and a hydrocarbon from the fuel electrode off gas discharged from the fuel electrode, and hydrogen in the removing unit. It is provided with an off-gas circulation path for supplying the fuel electrode off-gas from which at least one of carbon monoxide and hydrocarbon has been removed to the reforming section.

According to the solid carbon capture type energy supply system according to claim 6, the carbon dioxide concentration of the fuel electrode off-gas after removing at least one of hydrogen, carbon monoxide, and hydrocarbon in the removing part is increased to improve the carbon dioxide concentration. It can be supplied to the quality department.

The solid carbon recovery type energy supply system according to claim 7 is an off-gas heat exchange that exchanges heat between the air electrode off gas discharged from the air electrode of the fuel cell stack and at least one of the reforming portion and the carbon precipitation portion. It has a department.

According to the solid carbon recovery type energy supply system according to claim 7, the heat of the air electrode off gas and the fuel electrode off gas can be effectively used for heating one or both of the reforming portion and the carbon precipitation portion.

In the solid carbon recovery type energy supply system according to claim 8, the gas consuming unit has a combustion unit for burning the fuel gas, and the fuel gas and the oxidant gas are supplied to the combustion unit.

According to the solid carbon recovery type energy supply system according to claim 8, the reformed gas can be burned and the energy generated by the combustion can be used for power generation and heat exchange.

In the solid carbon recovery type energy supply system according to claim 9, the carbon dioxide separation unit that separates carbon dioxide from the combustion exhaust gas discharged from the combustion unit and the carbon dioxide separated by the carbon dioxide separation unit are reformed. It is equipped with a carbon dioxide circulation path that supplies the unit.

According to the solid carbon capture type energy supply system according to claim 9, the carbon dioxide separated by the carbon dioxide separation unit can be supplied to the reforming unit as a raw material.

The solid carbon recovery type energy supply system according to claim 10 includes a combustion exhaust gas discharged from the combustion unit and a combustion exhaust gas heat exchange unit that exchanges heat with at least one of the reforming unit and the carbon precipitation unit. There is.

According to the solid carbon capture type energy supply system according to claim 10, the heat of the combustion exhaust gas can be effectively used for heating one or both of the reforming portion and the carbon precipitation portion.

In the solid carbon recovery type energy supply method according to claim 11, a fuel gas containing a hydrocarbon is reformed with carbon dioxide in a reforming space to generate a reforming gas containing hydrogen and carbon monoxide, and the reforming space is described. Solid carbon is precipitated from the reformed gas at the carbon precipitation portion provided on the downstream side, and the reformed gas delivered from the carbon precipitation portion at the gas consumption portion provided on the downstream side of the carbon precipitation portion. To get energy by consuming.

In the solid carbon recovery type energy supply method according to claim 11, the fuel gas containing a hydrocarbon is reformed with carbon dioxide in the reformed space to generate a reformed gas containing hydrogen and carbon monoxide, downstream of the reformed space. Solid carbon is precipitated from the reformed gas at the carbon precipitation portion provided on the side.

By precipitating solid carbon in this way, carbon dioxide can be easily immobilized without being separately immobilized.

The reformed gas delivered from the carbon precipitation section is consumed by the gas consuming section provided on the downstream side of the carbon precipitation section to obtain energy.

In the solid carbon capture type energy supply method according to claim 12, water is separated from the reformed gas after use discharged from the gas consuming unit, and the reformed gas after use from which the water is separated is supplied to the reformed space. do.

According to the solid carbon capture type energy supply method according to claim 12, by supplying carbon dioxide in the reformed gas after use from which water is separated to the reformed space, carbon dioxide is not discharged to the outside and carbon dioxide is emitted. It can be used as a raw material for carbon reforming.

According to the solid carbon recovery type energy supply system and the solid carbon recovery type energy supply method according to the present invention, carbon dioxide can be easily immobilized.

It is a schematic diagram of the fuel cell system which concerns on 1st Embodiment. (A) is a schematic view of the inside of the reformed portion and the carbon precipitation portion of the fuel cell system according to the first embodiment, and (B) is a cross-sectional view taken along the line BB of (A). be. It is a block diagram of the control system of the fuel cell system which concerns on 1st Embodiment. It is a flowchart of the carbon precipitation monitoring process of 1st Embodiment. It is the schematic of the fuel cell system which concerns on the modification of 1st Embodiment. It is the schematic of the fuel cell system which concerns on other modification of 1st Embodiment. It is a schematic diagram of the fuel cell system which concerns on 2nd Embodiment. It is a schematic diagram of the solid carbon capture type energy supply system which concerns on 3rd Embodiment. It is a schematic diagram of the solid carbon capture type energy supply system which concerns on 4th Embodiment.

Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows a fuel cell system 10A according to a first embodiment as an example of the solid carbon recovery type energy supply system of the present invention. The fuel cell system 10A includes, as main configurations, reforming units 12A and 12B, carbon precipitation units 14A and 14B, a fuel cell stack 16, a condenser 20, and an exhaust heat input type absorption chiller 22. It also includes a fuel supply blower B1, an air blower B2, a circulation blower B3, a pump P1, and a cooling tower 24. Further, as shown in FIG. 3, a control unit 30 for controlling the fuel cell system 10A is provided.

The fuel supply blower B1 is connected to one end of the fuel supply pipe R1 and supplies fuel gas from the upstream side of the fuel supply pipe R1. The other end of the fuel supply pipe R1 is branched into two by a branch valve V1 and is connected to the reforming section 12A and the reforming section 12B.

In this embodiment, methane is used as a raw material gas, but the present invention is not particularly limited as long as it is a hydrocarbon-based gas that can be reformed, and is not limited to natural gas, LP gas (liquefied petroleum gas), coal reforming gas, and lower hydrocarbon gas. Etc. are exemplified. The hydrocarbon gas may be a mixture of the above-mentioned lower hydrocarbon gas, and the above-mentioned lower hydrocarbon gas may be a gas such as natural gas, city gas, or LP gas.

Further, as the hydrocarbon gas, biogas or digestion gas can also be used. Since biogas and digestion gas contain carbon dioxide, it is not necessary to supply carbon dioxide separately for reforming when reforming carbon dioxide, and carbon dioxide in biogas and digestion gas can be removed. Since it can be converted to solid carbon, it is suitable as a fuel gas. Furthermore, since carbon dioxide in biogas and digestion gas is derived from biomass that has absorbed carbon dioxide in the atmosphere, if it is recovered and immobilized as solid carbon, carbon dioxide in the atmosphere can be efficiently recovered. Since it will be reduced, it has a large effect of reducing carbon dioxide in the atmosphere as a measure against global warming, and is suitable as a fuel gas.

Methane as a fuel gas is sent to the reforming section 12A or the reforming section 12B via the branch valve V1 provided in the fuel supply pipe R1. In the present embodiment, there are two paths for supplying fuel gas to the fuel cell stack 16, one of which is provided with a reforming section 12A and a carbon precipitation section 14A, and the other path is provided with a reforming section 12B. , A carbon precipitation portion 14B is provided. The supply of fuel gas to one path and the other path is switched at any time according to the carbon precipitation state.

In the reforming section 12A, methane is reformed with carbon dioxide to generate a reforming gas containing hydrogen and carbon monoxide. As shown in FIG. 2, the reforming section 12A is provided with the reforming space 12AR, and the reforming space 12AR is filled with the reforming catalyst C. As the reforming catalyst C, in addition to alumina-supported nickel (Ni / Al ₂ O ₃ ), magnesia-supported nickel (Ni / MgO), aluminum-magnesium-supported nickel (Ni / Al ₂ MgO ₄₎ , and a mixture thereof are used. be able to. Reformation is carried out by the reaction of the following formula (1) with methane and carbon dioxide. The reforming section 12B has the same configuration as the modifying section 12A.

CH ₄ + CO ₂ → 2H ₂ + 2CO… (1)

The carbon precipitation portion 14A is a tubular tube body 14AK, and a tube such as stainless steel or iron can be used. The carbon precipitation section 14A is provided on the downstream side of the modification section 12A, and has a continuous space 14AC and a precipitation space 14AR.

The continuous space 14AC is continuous with the reforming space 12AR, and the reforming gas flows in from the reforming space 12AR. The inner wall 14ACW (inner wall of the tubular body 14AK) of the continuous space 14AC is flush with no unevenness, and the turbulent flow of the reformed gas is suppressed. By having this continuous space 14AC, the precipitation of solid carbon on the reforming catalyst C housed in the reforming section 12A is suppressed due to the influence of the turbulent flow in the precipitation space 14AR, which will be described later.

The precipitation space 14AR is continuously formed on the downstream side of the continuous space 14AC, and the reforming gas flows in from the continuous space 14AC. The precipitation space 14AR is continuously formed with the modified space 12AR. The inner wall 14AKW of the tube body 14AK in the precipitation space 14AR is provided with ribs 14AL protruding inward from the inner wall 14AKW at a plurality of places. The rib 14AL causes turbulence in the reformed gas passing through the precipitation space 14AR. In the present embodiment, they are formed at four locations in the circumferential direction and at equal intervals in the longitudinal direction. The carbon precipitation portion 14B has the same structure as the carbon precipitation portion 14A, and is connected to the reforming portion 12B. In the carbon precipitation section 14A, solid carbon is precipitated by the reaction of the following formulas (2) and (3).

The precipitation space 14AR may be formed of a flush single tube having no ribs and having no unevenness in order to maintain a constant gas flow rate while the flow path is blocked due to carbon precipitation, while carbon. When forming a flow path system that further promotes precipitation, a metal honeycomb plate such as stainless steel or iron may be inserted into the pipeline in order to increase the carbon precipitation area in the flow path.

CH ₄ → C + 2H ₂ … (2)
2CO → C + 2CO ₂ … (3)

The reforming portions 12A and 12B and the carbon precipitation portions 14A and 14B are arranged in the high temperature portion 13. The high temperature portion 13 is partitioned by a heat insulating material or the like, and is heated by an air electrode off gas described later, and the inside is maintained at a high temperature.

The branch valve V1 switches the supply destination of the fuel gas from the fuel supply pipe R1 to either the reforming unit 12A or the reforming unit 12B. The branch valve V1 is connected to the control unit 30, and switching is performed by the control unit 30.

A reformed gas pipe R2 is connected to the downstream ends of the carbon precipitation portion 14A and the carbon precipitation portion 14B. Each reformed gas pipe R2 merges at the merging valve V2 and is connected to the fuel electrode 16A of the fuel cell stack 16 via the merging valve V2. The merging valve V2 is controlled in conjunction with the branch valve V1, and when the fuel gas is supplied to the reforming portion 12A side, the flow path on the carbon precipitation portion 14A side is opened and the reforming portion 12B side. When the fuel gas is supplied, the flow path on the carbon precipitation portion 14B side is opened.

The reformed gas pipe R2 connected to the carbon precipitation portion 14A and the carbon precipitation portion 14B is provided with flow meters 15A and 15B, respectively. The flow rates of the reformed gas delivered from the carbon precipitation portions 14A and 14B are measured by the flow meters 15A and 15B. The flow meters 15A and 15B are connected to the control unit 30, and the flow rate data measured from the flow meters 15A and 15B is transmitted to the control unit 30. A pressure gauge may be provided instead of the flow meters 15A and 15B, respectively.

The reforming section 12A and the carbon precipitation section 14A are removable from the fuel supply pipe R1 and the reforming gas pipe R2, and can be replaced at any time.

The fuel cell stack 16 uses a solid oxide fuel cell (SOFC), and has an electrolyte layer 16C, fuel electrodes 16A laminated on the front and back surfaces of the electrolyte layer 16C, and air. It has a pole 16B and.

One end of the fuel supply pipe R1 is connected to the fuel electrode 16A of the fuel cell stack 16, and the other end of the fuel supply pipe R1 is connected to a gas source (not shown). Fuel gas is sent from the gas source by the fuel supply blower B1. In this embodiment, methane is used as the fuel gas, but the gas is not particularly limited as long as it can generate hydrogen by reforming, and a hydrocarbon fuel can be used. Examples of the hydrocarbon fuel include natural gas, LP gas (liquefied petroleum gas), biogas, coal reforming gas, and lower hydrocarbon gas. Examples of the lower hydrocarbon gas include lower hydrocarbons having 4 or less carbon atoms such as methane, ethane, ethylene, propane and butane, and methane used in the present embodiment is preferable. The hydrocarbon fuel may be a mixture of the above-mentioned lower hydrocarbon gas, and the above-mentioned lower hydrocarbon gas may be a gas such as natural gas, city gas, or LP gas. If the raw material gas contains impurities, a desulfurizer or the like is required, but it is omitted in the figure.

One end of the air supply pipe R5 is connected to the air electrode 16B of the fuel cell stack 16. An air blower B2 is connected to the other end of the air supply pipe R5. Air (oxidizing agent gas) is supplied to the air electrode 16B by the air blower B2. At the air electrode 16B, as shown in the following equation (4), oxygen in the air reacts with electrons to generate oxygen ions. The generated oxygen ions pass through the electrolyte layer 16C and reach the fuel electrode 16A of the fuel cell stack 16.

(Air pole reaction)
1 / 2O ₂ + ^2e- → O ^2- … (4)

Further, an air electrode off gas pipe R6 that sends out an air electrode off gas from the air electrode 16B is connected to the air electrode 16B.

On the other hand, in the fuel electrode 16A of the fuel cell stack 16, oxygen ions that have passed through the electrolyte layer 16C react with hydrogen and carbon monoxide in the fuel gas, as shown in the following equations (5) and (6). , Water (steam) and carbon dioxide and electrons are generated. The electrons generated in the fuel electrode 16A move from the fuel electrode 16A to the air electrode 16B through an external circuit (not shown), so that electricity is generated in each fuel cell. In addition, each fuel cell generates heat during power generation.

(Fuel electrode reaction)
H ₂ + O ^2- → H ₂ O + 2e -... ⁽ 5)
CO + O ^2- → CO ₂ + 2e ^－ … (6)

One end of the fuel electrode off gas pipe R3 is connected to the fuel electrode 16A of the fuel cell stack 16, and the fuel electrode off gas is discharged from the fuel electrode 16A to the fuel electrode off gas pipe R3. The fuel electrode off-gas contains unreacted hydrogen, unreacted carbon monoxide, carbon dioxide, water vapor and the like.

A condenser 20 is connected to the other end of the fuel electrode off gas pipe R3. The condenser 20 condenses the water in the off-gas fuel electrode. A water discharge pipe R20 is connected to the condenser 20, and water is discharged from the water discharge pipe R20 and sent to the water tank 21. A cooling water circulation flow path 22A is piped in the condenser 20, and cooling water from the exhaust heat input type absorption chiller 22 described later is circulated and supplied to cool the fuel electrode off gas. As a result, the water vapor in the combustion off gas is condensed.

One end of the circulating gas pipe R4 is connected to the condenser 20, and the fuel electrode off gas after removing water is sent to the circulating gas pipe R4. The other end of the circulating gas pipe R4 is connected to the fuel supply pipe R1 via the gas mixer GM. The circulation gas pipe R4 is provided with a circulation blower B3. The fuel electrode off gas is sent out toward the fuel supply pipe R1 by the circulation blower B3, mixed with the fuel gas by the gas mixer GM, and supplied to the reforming units 12A and 12B.

The air electrode off gas pipe R6 is branched into a high temperature part heat exchange pipe R6A and a refrigerator heat exchange pipe R6B. The high temperature section heat exchange pipe R6A is arranged so that heat exchange is performed in the high temperature section 13. The temperature of the high temperature portion 13 is maintained at about 500 ° C. to 700 ° C. by the air electrode off gas, and the reforming portions 12A and 12B and the carbon precipitation portions 14A and 14B are heated. The refrigerator heat exchange pipe R6B is connected to the exhaust heat input type absorption chiller 22 described later.

The exhaust heat input type absorption chiller 22 is a heat pump that generates cold heat using exhaust heat, and as an example, a steam / exhaust heat input type absorption chiller can be used. In the vapor / exhaust heat input type absorption chiller, water is separated from the absorption liquid and regenerated by heating the absorption liquid that has absorbed steam (for example, lithium bromide aqueous solution or ammonia aqueous solution) by the heat of the air electrode off gas. do. The air electrode off gas cooled by heating the absorption liquid is exhausted to the outside of the exhaust heat input type absorption chiller 22.

The absorbing liquid regenerated by heating promotes the evaporation of water by absorbing water vapor and contributes to the generation of cold heat. The exhaust heat input type absorption chiller 22 is connected to the cooling tower 24 via the heat dissipation circuit 24A. A pump (not shown) is installed in the heat radiating circuit 24A, and the pump supplies cooling water to the heat radiating circuit 24A. The absorbed heat generated when the absorption liquid absorbs water vapor in the exhaust heat input type absorption chiller 22 is released from the cooling tower 24 to the atmosphere through the cooling water flowing through the heat dissipation circuit 24A.

The cold heat generated by the exhaust heat input type absorption type refrigerator 22 is sent to the condenser 20 via the cooling water flowing through the cooling water circulation flow path 22A, and the fuel electrode off gas is cooled by the condenser 20 and is contained in the fuel electrode off gas. The water vapor is condensed and removed and stored in the water tank 21.

The water tank 21 is connected to a cooling water circulation flow path 22A, a heat dissipation circuit 24A, and a heat medium flow path (not shown) through which water flows as a heat medium of the waste heat input type absorption chiller 22. In the cooling water circulation flow path 22A, the heat dissipation circuit 24A, and the heat medium flow path, when water is insufficient, water is appropriately replenished from the water tank 21 by the pump P1.

The control unit 30 controls the entire fuel cell system 10A, and includes a CPU, a ROM, a RAM, a memory, and the like. The memory stores carbon precipitation monitoring processing, which will be described later, a flow rate fluctuation threshold value F which is an index of carbon precipitation state, data and procedures necessary for processing during normal operation, and the like. As shown in FIG. 3, the control unit 30 is connected to a branch valve V1, a merging valve V2, and flow meters 15A and 15B. The branch valve V1 and the merging valve V2 are controlled by the control unit 30. Note that FIG. 3 shows a part of the connection relationship of the control unit 30 in the fuel cell system 10A, and although not shown in FIG. 3, the control unit 30 is also connected to other devices.

The flow rate fluctuation threshold F is a value that is an index of the carbon precipitation state in the carbon precipitation portions 14A and 14B, and is an allowable change amount from the flow rate F0 when the carbon precipitation amount is zero according to the output of the fuel supply blower B1. be. When the change in the flow rate of the reformed gas flowing through the reformed gas pipe R2 becomes equal to or higher than the flow rate fluctuation threshold value F, it is time to replace the reformed portions 12A and 12B and the carbon precipitation portions 14A and 14B.

Next, the operation of the fuel cell system 10A of the present embodiment will be described.

In the fuel cell system 10A, the fuel gas is sent from the gas source to the fuel supply pipe R1 by the fuel supply blower B1. Further, the fuel electrode off gas mainly containing carbon dioxide, carbon monoxide, and hydrogen is sent from the circulating gas pipe R4 to the fuel supply pipe R1 via the gas mixer GM.

The branch valve V1 and the merging valve V2 are controlled so that the path of the reforming section 12A and the carbon precipitation section 14A or the path of the reforming section 12B and the carbon precipitation section 14B is opened. In the reforming sections 12A and 12B, the fuel gas is reformed with carbon dioxide, and the reforming gas containing hydrogen and carbon monoxide is sent to the carbon precipitation sections 14A and 14B.

In the carbon precipitation portions 14A and 14B, the reformed gas flows into the continuous spaces 14AC and 14BC, and the reformed gas that has passed through the continuous spaces 14AC and 14BC hits the ribs 14AL and 14BL in the precipitation spaces 14AR and 14BR, causing turbulence. Solid carbon is deposited on the inner walls 14AKW and 14BKW of the precipitation spaces 14AR and 14BR by the reaction of the above formulas (2) and (3).

The reforming gas that has passed through the carbon precipitation portions 14A and 14B is supplied to the fuel electrode 16A of the fuel cell stack 16. In the fuel cell stack 16, air from the air blower B2 is supplied to the air electrode 16B, power is generated by a power generation reaction, and electricity is taken out from an electric wiring (not shown).

The fuel electrode off gas discharged from the fuel electrode 16A is sent to the condenser 20, water is removed by condensation, and the gas is returned to the fuel supply pipe R1. A part of the air electrode off gas discharged from the air electrode 16B is used for heat exchange in the high temperature section 13, and a part is used for heat exchange in the exhaust heat input type absorption chiller 22.

Here, the carbon precipitation monitoring process executed by the control unit 30 will be described. During the operation of the fuel cell system 10A, the control unit 30 executes the carbon precipitation monitoring process shown in FIG.

In step S10, the flow rate measured by the flow meter 15A or the flow meter 15B is acquired, and in step S12, the flow rate fluctuation value F1 is calculated from the acquired flow rate. The flow rate fluctuation value F1 can be obtained from the difference between the flow rate F0 in the reformed gas pipe R2 when the carbon precipitation amount is zero and the acquired flow rate according to the output of the fuel supply blower B1.

In step S14, it is determined whether or not the flow rate fluctuation value F1 is equal to or higher than the flow rate fluctuation threshold value F recorded in advance, and if the determination is affirmed, the process proceeds to step S16. If the judgment is denied, the process waits until the flow rate fluctuation value F1 becomes equal to or higher than the flow rate fluctuation threshold value F1.

In step S16, the branch valve V1 is switched, and in step S18, the merging valve V2 is switched. By this switching, the fuel gas supply destination is switched. When the reforming section 12A and the carbon precipitation section 14A were used, the modification section 12B and the carbon precipitation section 14B were switched to, and when the reforming section 12B and the carbon precipitation section 14B were used, the modification was performed. It switches to the quality part 12B and the carbon precipitation part 14A. By this switching, it is possible to replace the reforming portions 12A and 12B and the carbon precipitation portions 14A and 14B on the side where the fuel gas supply is stopped. As a result, it is possible to reduce the influence on the system due to the blockage of the flow path, and to continuously supply the fuel gas and recover the carbon.

After step S18, the process returns to step S10 and the above process is repeated.

According to the fuel cell system 10A of the present embodiment, solid carbon is precipitated from the reformed gas at the carbon precipitation portions 14A and 14B. By precipitating solid carbon in this way, treatment can be easily performed. As a result, carbon dioxide generated during power generation using hydrocarbon fuel can be easily recovered as solid carbon that can be easily transported and immobilized.
In particular, in an energy supply system that uses fossil fuel-derived hydrocarbon fuels, the recovered solid carbon can be immobilized by reducing the emission of carbon dioxide generated during energy creation and recovering it as solid carbon that can be easily immobilized. For example, it is possible to supply carbon-neutral energy without releasing carbon dioxide into the atmosphere while using fossil fuels.

Further, since the carbon dioxide contained in the fuel electrode off gas discharged from the fuel electrode 16A is returned to the reforming units 12A and 12B and used for the carbon dioxide reforming, the carbon dioxide generated by the operation of the fuel cell system 10A is used. It can be recovered as solid carbon dioxide without being discharged to the outside.

In the present embodiment, carbon dioxide for carbon dioxide reforming in the reforming unit 12 is supplied by returning the fuel electrode off gas, but when biogas or digestion gas is used as the fuel gas, the fuel gas is used. Since carbon dioxide is contained in the fuel, it is not always necessary to return the fuel electrode off gas to the reforming unit 12. Further, as the supply of carbon dioxide to the reforming unit 12, carbon dioxide in the atmosphere, carbon dioxide contained in exhaust gas from a factory, or the like may be used.
By mixing carbon dioxide contained in biogas and carbon dioxide contained in the atmosphere, and recovering and immobilizing a part of these as solid carbon, carbon dioxide accumulated in the atmosphere is recovered and reduced. Is possible.

In the present embodiment, with respect to the fuel electrode off-gas, only water is removed while unreacted carbon monoxide and hydrogen remain and supplied to the reforming units 12A and 12B. As shown in FIG. 5, the fuel is supplied. An oxidizing portion 18 may be provided on the downstream side of the battery cell stack 16. The oxidizing unit 18 is provided with an oxygen permeation membrane 18C so as to partition the fuel electrode flow path 18A and the air electrode flow path 18B, and moves oxygen from the air electrode flow path 18B to the fuel electrode flow path 18A side. As a result, hydrogen, carbon monoxide, etc. in the fuel electrode off-gas are removed by the oxidation reaction as in the formulas (7) and (8).

2H ₂ + O ₂ → 2H ₂ O… (7)
2CO + O ₂ → 2CO ₂ ... (8)

Further, as shown in FIG. 6, a hydrogen removing unit 19 may be provided on the downstream side of the fuel cell stack 16. The hydrogen removing unit 19 is provided with a hydrogen permeation membrane 19C so as to partition the fuel electrode flow path 19A and the air electrode flow path 19B, and moves hydrogen from the fuel electrode flow path 19A to the air electrode flow path 19B side. This makes it possible to remove hydrogen from the off-gas fuel electrode.

Further, in the present embodiment, a plurality of reforming portions 12A and 12B and carbon precipitation portions 14A and 14B are provided, and the fuel gas supply destination is switched by the carbon precipitation monitoring process. Therefore, the reforming portions 12A and 12B and the carbon precipitation portions 14A and 14B on the side where the fuel gas supply is stopped can be easily replaced without stopping the fuel cell system 10A.

Further, in the present embodiment, the air electrode off gas is used for heating the reforming portions 12A and 12B and the carbon precipitation portions 14A and 14B while maintaining the temperature of the high temperature portion 13, so that the heat energy can be effectively used. .. Further, since the air electrode off gas is used for heat exchange at the time of cold heat generation in the exhaust heat input type absorption chiller 22, the heat energy can be effectively used.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the fuel cell system 10B of the present embodiment, as shown in FIG. 7, instead of the fuel cell stack 16, a fuel cell of a hydrogen ion conduction type solid oxide fuel cell (PCFC: Proton Ceramic Solid Oxide Fuel Cell) is used. The cell stack 17 is used. The fuel cell stack 17 has a fuel electrode 17A, an air electrode 17B, and an electrolyte layer 17C.

A steam supply pipe R7B is connected between the merging valve V2 and the fuel electrode 17A, and steam is supplied to the fuel electrode 17A. The steam supply pipe R7B is connected to the vaporizer 28. Water is supplied to the vaporizer 28 from the water tank 21. The supplied water (liquid phase) is heated and vaporized by the fuel electrode off gas flowing through the fuel electrode off gas pipe R3 in the vaporizer 28.

In the fuel electrode 17A, as shown in the following equation (9), the unreformed fuel gas is steam reformed in the reforming section 12A to generate hydrogen and carbon monoxide. Further, as shown in the following equation (10), carbon dioxide and hydrogen are generated by the shift reaction between the generated carbon monoxide and water.

CH ₄ + H ₂ O → 3H ₂ + CO… (9)
CO + H ₂ O → CO ₂ + H ₂ … (10)

Then, in the fuel electrode 17A, hydrogen is separated into hydrogen ions and electrons as shown in the following equation (11).

(Fuel electrode reaction)
H ₂ → 2H ⁺ + 2e ^－ … (11)

Hydrogen ions move through the electrolyte layer 17C to the air electrode 17B. The electrons move to the air pole 17B through an external circuit (not shown). As a result, power is generated in the fuel cell stack 17. During power generation, the fuel cell stack 17 generates heat.

In the air electrode 17B, as shown in the following equation (12), hydrogen ions transferred from the fuel electrode 17A through the electrolyte layer 17C and electrons transferred from the fuel electrode 16A through the external circuit are combined with oxygen in the air. The reaction produces water vapor.

(Air pole reaction)
2H ⁺ + ^2e- + 1 / 2O ₂ → H _2O ... (12)

Also in the fuel cell system 10B of the present embodiment, as in the first embodiment, the carbon precipitation portions 14A and 14B precipitate solid carbon from the reformed gas, so that carbon dioxide can be easily treated. As a result, carbon dioxide generated during power generation using hydrocarbon fuel can be easily recovered as solid carbon that can be easily transported and immobilized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first and second embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, as a gas consuming device, an energy supply system 10C that generates electricity with energy obtained by burning fuel will be described. A gas engine or a gas turbine generator can be used, but in this embodiment, a gas engine will be described as an example.

Also in this embodiment, the same fuel gas as in the first embodiment can be used.

As shown in FIG. 8, the downstream end of the reforming gas pipe R2 and the downstream end of the air supply pipe R5 are connected to the gas engine 40. The reformed gas pipe R2 supplies the reformed gas to the fuel chamber (not shown) of the gas engine 40, and the air supply pipe R5 supplies air to the combustion chamber of the gas engine 40. The reformed gas is burned by air in the combustion chamber.

A combustion exhaust gas pipe R8 is connected to the gas engine 40, and the combustion exhaust gas is sent from the combustion chamber to the combustion exhaust gas pipe R8. The combustion exhaust gas pipe R8 is branched into a high temperature part heat exchange pipe R8A and a refrigerator heat exchange pipe R8B. The high temperature section heat exchange pipe R8A is arranged so that heat exchange is performed in the high temperature section 13. The temperature of the high temperature portion 13 is maintained at about 500 ° C. to 700 ° C. by the combustion exhaust gas, and the reforming portions 12A and 12B and the carbon precipitation portions 14A and 14B are heated.

The refrigerator heat exchange pipe R8B is connected to the exhaust heat input type absorption chiller 22. The combustion exhaust gas is cooled by heat exchange in the exhaust heat input type absorption chiller 22 and sent to the condenser 20 for further cooling. As a result, water vapor in the combustion exhaust gas is removed.

One end of the circulating gas pipe R10A is connected to the condenser 20, and the other end of the circulating gas pipe R10A is connected to the carbon dioxide separation unit 31. The carbon dioxide separation unit 31 has a non-permeable unit 32 and a permeation unit 34 partitioned by the carbon dioxide separation membrane 33. The carbon dioxide separation membrane 33 is formed of a membrane that selectively permeates carbon dioxide. The circulating gas pipe R10A is connected to the impermeable portion 32, and the combustion exhaust gas after the water is removed by the condenser 20 is supplied to the impermeable portion 32 of the carbon dioxide separation unit 31. The carbon dioxide in the combustion exhaust gas supplied to the non-permeation portion 32 permeates through the carbon dioxide separation membrane 33 and moves to the permeation portion 34. The combustion exhaust gas component remaining in the non-permeation portion 32 is discharged from the exhaust gas pipe R11.

One end of the circulating gas pipe R10B is connected to the permeation portion 34 of the carbon dioxide separation portion 31, and the other end of the circulating gas pipe R10B is connected to the fuel supply pipe R1 via the gas mixer GM. The circulation gas pipe R10B is provided with a circulation blower B3. The carbon dioxide separated by the carbon dioxide separation unit 31 is sent out to the fuel supply pipe R1 by the circulation blower B3, mixed with the fuel gas by the gas mixer GM, and supplied to the reforming units 12A and 12B.

Also in the energy supply system 10C of the present embodiment, solid carbon is precipitated from the reformed gas at the carbon precipitation portions 14A and 14B. By precipitating solid carbon in this way, treatment can be easily performed. As a result, carbon dioxide generated during power generation using hydrocarbon fuel can be easily recovered as solid carbon that can be easily transported and immobilized.

Further, since the carbon dioxide contained in the combustion exhaust gas discharged from the gas engine 40 is returned to the reforming units 12A and 12B and used for carbon dioxide reforming, the carbon dioxide generated by the operation of the energy supply system 10C can be used. It can be recovered as solid carbon dioxide without being discharged to the outside.

[Fourth Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first to third embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, an energy supply system 10D that utilizes heat energy obtained by burning fuel as a gas consuming device will be described. A gas water heater or a gas boiler can be used, but in the present embodiment, the gas water heater will be described as an example.

Also in this embodiment, the same fuel gas as in the first embodiment can be used.

As shown in FIG. 9, the downstream end of the reforming gas pipe R2 and the downstream end of the air supply pipe R5 are connected to the gas water heater 44. The reforming gas pipe R2 supplies the reforming gas to the fuel chamber (not shown) of the gas water heater 44, and the air supply pipe R5 supplies air to the combustion chamber of the gas water heater 44. The reformed gas is burned by air in the combustion chamber.

The gas water heater 44 is provided with a heat exchange pipe 46, and water is supplied to the heat exchange pipe 46. The heat exchange pipe 46 is arranged so that the water flowing inside is heated by the heat of combustion in the combustion chamber.

A combustion exhaust gas pipe R8 is connected to the gas water heater 44, and the combustion exhaust gas is sent from the combustion chamber to the combustion exhaust gas pipe R8.

Also in the energy supply system 10D of the present embodiment, solid carbon is precipitated from the reformed gas at the carbon precipitation portions 14A and 14B. By precipitating solid carbon in this way, treatment can be easily performed. As a result, carbon dioxide generated during power generation using hydrocarbon fuel can be easily recovered as solid carbon that can be easily transported and immobilized.

Further, since the carbon dioxide contained in the combustion exhaust gas discharged from the gas water heater 44 is returned to the reforming units 12A and 12B and used for carbon dioxide reforming, the carbon dioxide generated by the operation of the energy supply system 10C is used. It can be recovered as solid carbon dioxide without being discharged to the outside.

In the above-mentioned first to fourth embodiments, the rib 14AL is provided on the inner wall 14AKW of the tube body 14AK in the precipitation space 14AR of the carbon precipitation portions 14A and 14B to promote carbon precipitation, but the rib 14AL is not always necessary. is not it. Instead of the rib 14AL, the surface of the inner wall 14AKW may be roughened or fine irregularities may be formed.

Further, in the above-mentioned first to fourth embodiments, carbon dioxide contained in the gas discharged from each gas consuming device (fuel cell cell stack 16, gas engine 40, gas water heater 44) is converted into reforming units 12A and 12B. Although it was used for carbon dioxide reforming in, other carbon dioxide may be used.

Further, in the above-mentioned first to fourth embodiments, two sets of the reforming portions 12A and 12B and the carbon precipitation portions 14A and 14B are installed, but three or more sets may be installed or one set may be installed. By providing two or more sets, the carbon precipitation portions 14A and 14B can be replaced without stopping the supply of fuel gas.

Further, in the above-mentioned first to fourth embodiments, the waste heat input type absorption chiller 22 is used to generate cold heat, but other exhaust heat is used instead of the exhaust heat input type absorption chiller 22. Cold heat may be generated using a heat pump, for example, an adsorption chiller.
Further, in order to remove (dehumidify) the moisture in the exhaust gas by using the exhaust heat, the excess moisture in the gas may be removed by using the exhaust heat utilization type desiccant air conditioner.

10A, 10B fuel cell system (solid carbon capture type energy supply system)
10C, 10D Energy supply system 12A, 12B Remodeling section 12AR, 12BR Remodeling space C Remodeling catalyst 13 High temperature section (off-gas heat exchange section, combustion exhaust gas heat exchange section)
14A, 14B Carbon deposit section 15A, 15B Flow meter (carbon information output section)
16, 17 Fuel cell cell stack (gas consumption unit)
16A, 17A Fuel pole 16B, 17B Air pole 18 Oxidizing part (removing part)
19 Hydrogen removal part (removal part)
20 Condensator (water separator)
31 Carbon dioxide separation unit 30 Control unit (switching unit)
40 Gas engine (Gas consumption department)
44 Gas water heater (Gas Consumption Department)
R4 circulation gas pipe (off gas circulation path)
R10B circulation gas pipe (carbon cycle)
V1 branch valve (switching part)
V2 merging valve (switching part)

Claims (12)

It has a reforming space in which a reforming catalyst is housed, and the fuel gas containing hydrocarbons is reformed with carbon dioxide in the reforming space to generate a reforming gas containing hydrogen and carbon monoxide. With the quality department
A carbon precipitation section provided on the downstream side of the reforming section and depositing solid carbon from the reforming gas delivered from the reforming section.
A gas consuming unit provided on the downstream side of the carbon precipitation unit and consuming the reformed gas sent from the carbon precipitation unit to obtain energy.
A solid carbon capture and storage energy supply system equipped with. A water separation unit that separates water from the reformed gas after use discharged from the gas consumption unit, and a water separation unit.
A gas circulation path for supplying the reformed gas after use, in which water is separated in the water separation section, to the reforming section.
The solid carbon capture type energy supply system according to claim 1. It is provided on the downstream side of the carbon precipitation part and on the upstream side of the gas consuming part, and at least one of the flow rate and the pressure of the reformed gas sent out from the carbon precipitation part is measured and precipitated at the carbon precipitation part. A carbon information output unit that outputs precipitated carbon information regarding the amount of carbon that has been formed,
The solid carbon capture type energy supply system according to claim 1 or 2, comprising the above. With the plurality of carbon precipitates,
A switching unit for switching the carbon precipitation unit to which the reforming gas is sent from the reforming unit among the plurality of carbon precipitation units based on the deposited carbon information output from the carbon information output unit. ,
3. The solid carbon capture and storage energy supply system according to claim 3. The gas consuming unit is a fuel cell stack that uses the reformed gas for a power generation reaction, and the fuel gas is supplied to the fuel electrode of the fuel cell stack.
The solid carbon capture type energy supply system according to any one of claims 1 to 4. A removal unit that removes at least one of hydrogen, carbon monoxide, and hydrocarbons from the fuel electrode off-gas discharged from the fuel electrode.
An off-gas circulation path that supplies the fuel electrode off-gas from which at least one of hydrogen, carbon monoxide, and hydrocarbon has been removed by the removing section to the reforming section.
5. The solid carbon capture and storage energy supply system according to claim 5. An off-gas heat exchange unit that exchanges heat with at least one of the reforming unit and the carbon precipitation unit with the air electrode off-gas discharged from the air electrode of the fuel cell stack.
5. The solid carbon capture and storage energy supply system according to claim 5 or 6. The gas consuming unit has a combustion unit that burns the fuel gas.
The solid carbon recovery type energy supply system according to any one of claims 1 to 4, wherein the fuel gas and the oxidant gas are supplied to the combustion unit. A carbon dioxide separation unit that separates carbon dioxide from the combustion exhaust gas discharged from the combustion unit,
A carbon dioxide cycle that supplies carbon dioxide separated by the carbon dioxide separation unit to the reforming unit, and
8. The solid carbon capture and storage energy supply system according to claim 8. A combustion exhaust gas heat exchange unit that exchanges heat with at least one of the combustion exhaust gas discharged from the combustion unit, the reforming unit, and the carbon precipitation unit.
The solid carbon capture type energy supply system according to claim 8 or 9. The fuel gas containing hydrocarbons is reformed with carbon dioxide in the reforming space to generate a reformed gas containing hydrogen and carbon monoxide.
Solid carbon is precipitated from the reformed gas at a carbon precipitation portion provided on the downstream side of the reformed space.
A gas consuming section provided on the downstream side of the carbon precipitation section consumes the reformed gas sent from the carbon precipitation section to obtain energy.
Solid carbon capture type energy supply method. Separate water from the reformed gas after use discharged from the gas consuming part,
Supplying the reformed gas after use from which water is separated to the reformed space,
The solid carbon capture type energy supply method according to claim 11.

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