JP2002191961A - Composite type carbon dioxide fixing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize the synthetic energy possessed by raw material gas without adjusting a compositional ratio even if methane being reactive gas and carbon dioxide are not equimolar. SOLUTION: In the outlet flow channel of a reactor 3, two flow channels, that is a circulating flow channel 10 for again returning a part of the exhaust gas from the reactor 3 to the reactor 3 and a flow channel 12 for guiding the remainder of the exhaust gas to a mechanism for taking out synthetic energy are connected. A part of the exhaust gas issued from the reactor 3 enters the circulating flow channel 10 and the remainder thereof enters the flow channel 12. A gas combustor 6, a hydrogen separator 7 and a gas turbine 8 are connected to the flow channel 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a reactor filled with a catalyst, and performs a catalytic reaction in the reactor using a mixed gas containing methane and carbon dioxide as a raw material to generate carbon and water, thereby producing carbon dioxide. The present invention relates to a device for immobilization. This device can also be used when methane and carbon dioxide are generated in the chemical industry and the environment.

[0002]

2. Description of the Related Art As one method of immobilizing carbon dioxide,
There is known a method of precipitating carbon by reducing carbon dioxide by a catalytic reaction in the presence of methane. The catalytic reaction between methane and carbon dioxide proceeds by the following reaction. CH ₄ → C + 2H ₂ (1) CO ₂ + 2H ₂ → C + 2H ₂ O (2) As a result of the equations (1) and (2), the following equation (3) is established. CH ₄ + CO ₂ → 2C + 2H ₂ O (3)

As can be seen from the equation (3), methane and carbon dioxide react in equimolar amounts. Therefore, if the molar ratio of methane and carbon dioxide in the raw material mixture gas is not equimolar, the deficient components will be equimolar. Or by separating the substance generated from the excess component and discharging the separated substance out of the system, the reaction for immobilizing carbon dioxide is adjusted to proceed in an equimolar manner.

[0004]

When the mixed gas composition of methane and carbon dioxide as raw materials is not in an equimolar state, the operation of adjusting the equimolarity is troublesome, and the immobilization reaction of carbon dioxide is made inefficient. ing. Therefore, the present invention aims to eliminate the need to adjust the equimolar amounts of the reaction gases methane and carbon dioxide even when they are not equimolar, and to make effective use of the total energy of the raw material mixed gas. is there.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a reactor filled with a catalyst, and a mixed gas containing methane and carbon dioxide is used as a raw material to cause a catalytic reaction in the reactor to produce carbon and water. A device for immobilizing carbon, wherein at a discharge gas outlet of the reactor, a circulation flow path for returning a part of gas discharged from the reactor to the reactor again, and discharged from the reactor It is connected to a flow channel that leads the rest of the gas to a mechanism that extracts the total energy of the exhaust gas.

[0006] The reaction in a reactor for fixing carbon dioxide by generating carbon and water generally has a low conversion rate, but a part of the gas discharged from the reactor is reduced due to the provision of a circulation channel. Since it is returned to the reactor via the circulation channel, the conversion of the reaction for fixing carbon dioxide is improved.

Further, the remaining gas discharged from the reactor is led to a mechanism for extracting total energy via a flow channel, so that the composition is equimolar even when the reactant gas methane and carbon dioxide are not equimolar. Thus, the total energy of the raw material gas can be effectively used without performing the adjustment operation.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION It is preferable that a mechanism for extracting total energy includes at least one of a gas combustor, a hydrogen separator, and a gas turbine. The gas combustor can extract gas energy from the reactor in the form of heat, the hydrogen separator can extract hydrogen, and the gas turbine can extract electric power.

[0009] The mechanism for extracting the total energy may exist as a separate structure from the composite carbon dioxide fixing device, or may be integrated with the composite carbon dioxide fixing device. The integration makes it possible to compact the device.

[0010]

FIG. 1 schematically shows an embodiment. Reference numeral 1 denotes a supply pump for supplying a mixed gas as a raw material to the reactor 3, and the supplied mixed gas contains at least methane and carbon dioxide. The supplied mixed gas is a gas generated in a chemical industrial plant or a gas generated by anaerobic fermentation of organic waste. The mixed gas of methane and carbon dioxide resulting from anaerobic fermentation of organic waste contains a small amount of nitrogen.

A heater 2 is provided in a flow path between the supply pump 1 and the reactor 3 for heating the mixed gas supplied to the reactor 3 by the supply pump 1. Although the heater 2 is not particularly limited, since it heats the raw material mixed gas containing flammable methane, from the viewpoint of safety, as an example, the heater 2 is provided with a heat exchanger and heated by the heating gas. Use a heating system. The heater 2 is controlled to heat the gas flowing therethrough to 500 to 600 ° C.

The reactor 3 is filled with a catalyst 3a.
The catalyst 3a is, for example, a nickel catalyst supported on silica (SiO ₂ ), and has a catalyst component nickel content of 90%. The catalyst 3a may be in the form of a fixed bed supported by a support material such as glass wool in a reaction tube of the reactor, or may be in the state of a fluidized tank capable of flowing in the reactor 3. The temperature of the reactor 3 is maintained so that the gas heated by the heater 2 also maintains 500 to 600 ° C. in the reactor 3.

The outlet channel of the reactor 3 has a circulation channel 10 for returning a part of the exhaust gas from the reactor 3 to the reactor 3 again, and a mechanism for extracting the remaining energy of the exhaust gas from the exhaust gas. Are connected to each other, and a part of the exhaust gas discharged from the reactor 3 is
0, and the remainder enters the distribution channel 12.

The circulation passage 10 is connected to a passage between the supply pump 1 and the heater 2, and the circulation passage 10 is provided with a circulation pump 5. The gas discharged from the reactor 3 is
Unreacted gas (CH ₄ , CO ₂ ) and generated gas (H ₂ O, H ₂ )
And an intermediate product gas (CO). A condenser 4 is provided between the reactor 3 and the circulation pump 5 in the circulation channel 10 in order to take water out of the gas out of the system.

A gas combustor 6, a hydrogen separator 7, and a gas turbine 8 are connected to the flow passage 12 as a mechanism for extracting total energy. At least one of the gas combustor 6, the hydrogen separator 7, and the gas turbine 8 only needs to be connected, and when two or three are connected, the exhaust gas is divided and guided to each. May be switched and any of the mechanisms may be used. The energy of the gas from the reactor 3 can be extracted in the form of heat by the gas combustor 6, hydrogen can be extracted by the hydrogen separator 7, and can be extracted by electric power by the gas turbine 8.

The gas combustor 6, the hydrogen separator 7, and the gas turbine 8 may each be a general-purpose independent mechanism.
In that case, the flow channel 12 is a channel pipe that leads the exhaust gas of the reactor 3 to those mechanisms. Further, the gas combustor 6, the hydrogen separator 7, and the gas turbine 8 may be a dedicated one integrated with this reactor, and in that case, the whole can be designed to be compact.

Next, the operation of this embodiment will be described. The mixed gas supplied by the supply pump 1 is heated to 500 to 600 ° C. by the heater 2 and guided to the reactor 3. In the reactor 3, the reaction of the above formula (3) occurs, and the deposited carbon remains in the reactor 3. The reaction represented by the formula (3) generally has a low conversion of 20 to 30%.

A part of the gas discharged from the reactor 3 is supplied to the reactor 3 via the heater 2 together with the new reaction gas supplied from the supply pump 1 via the circulation flow path 10 and (3) ) Contributes to the reaction. The remainder of the gas discharged from the reactor 3 is guided to the gas combustor 6, the hydrogen separator 7, or the gas turbine 8 via the flow channel 12, and is taken out as the respective energy.

When a mixed gas produced by anaerobic fermentation of organic waste is used as a raw material, the mixed gas is in excess of methane. If methane is excessive, hydrogen is generated. conventionally,
In the case where CH ₄ and CO _{2 in} the mixed gas of the raw materials were not 1: 1, the gas of the insufficient component was supplied from the outside. A part of the discharged gas is guided to a gas combustor 6, a hydrogen separator 7, or a gas turbine 8, and is extracted in the form of heat, hydrogen, or electric power.

The gas produced by anaerobic fermentation of organic wastes contains a small amount of nitrogen. In the present invention, even if nitrogen is contained, the reaction of the formula (3) does not hinder the reaction, so that it is not necessary to remove by concentration. In the example, the reactor 3
Is heated by the heater 2, but this is not a limitation, and the heater 2 is eliminated,
The reactor 3 may be heated to a predetermined temperature in an electric furnace. In the present invention, since both the circulation channel 10 and the circulation channel 12 are provided, the generated water is gradually discharged from the circulation channel 12. Therefore, the condenser 4 in the circulation channel 10 can be omitted.

[0021]

According to the present invention, a circulation passage for returning a part of the gas discharged from the reactor to the reactor again at the exhaust gas outlet of the reactor filled with the catalyst, The remaining part is connected to a flow channel that leads to a mechanism that extracts the total energy of the exhaust gas, so that the conversion rate of the reaction for fixing carbon dioxide is improved and the reaction gas methane and carbon dioxide are equimolar. Even if it is not, without performing the operation of adjusting the composition ratio to replenish the missing components,
The total energy of the source gas can be used effectively.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Supply pump 2 Heater 3 Reactor 3a Catalyst 4 Condenser 5 Circulation pump 6 Gas combustor 7 Hydrogen separator 8 Gas turbine 10 Circulation flow path 12 Distribution flow path

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuo Nagaso 1 Nishinokyo Kuwabaracho, Nakagyo-ku, Kyoto-shi, Kyoto F-term in Shimadzu Corporation (reference) 4G046 CA01 CA02 CC08 4G075 AA04 AA37 AA43 AA44 AA63 BA01 BA06 BD12 CA54 CA56

Claims (3)

[Claims] An apparatus for fixing carbon dioxide by providing a reactor filled with a catalyst, performing a catalytic reaction in the reactor using a mixed gas containing methane and carbon dioxide as a raw material, and generating carbon and water, At the exhaust gas outlet of the reactor, a circulation flow path for returning a part of the gas discharged from the reactor to the reactor again, and the remaining gas discharged from the reactor as a whole having the exhaust gas A composite type carbon dioxide fixing device, wherein the device is connected to a flow channel leading to a mechanism for extracting energy. 2. The combined carbon dioxide fixing device according to claim 1, wherein the mechanism includes at least one of a gas combustor, a hydrogen separator, and a gas turbine. 3. The combined carbon dioxide fixing device according to claim 2, further comprising the mechanism.