JP2001158887A - Method and apparatus for producing synthetic natural gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus capable of efficiently mass-producing synthetic natural gas as a new energy source from a synthetic gas. SOLUTION: This apparatus has such a scheme that an anode 48 and a tubular anode 26 are concentrically set up inside housings 14, 16, 18 to provide a plasma reaction chamber 76 therebetween, and the reaction chamber 76 is packed with a methanation catalyst 78 followed by generating plasma arc under power supply between the electrodes to carry out a reaction between CO and H2 by the action of the methanation catalyst to obtain the objective methane- rich gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternative natural gas production method, and more particularly to a synthetic natural gas production method and apparatus.

[0002]

BACKGROUND ART As an effective measure against depletion of petroleum resources, air pollution due to exhaust gas from factories and automobiles, and global warming due to carbon dioxide emission, in recent years, it has been used as a fuel for transportation equipment such as automobiles and ships, or for power generation Natural gas has attracted attention as a fuel. In addition, natural gas is widely used for city gas year by year. In particular, a method for producing alternative natural gas has been proposed as a measure against peak loads.

[0003] US Pat. No. 4,092,129 discloses that a porous electrode is arranged in an electrolytic cell and H ₂ and O ₂ are electrolyzed.
And reacting O ₂ with the coal powder to produce CO;
On the other hand, a synthetic natural gas production method and an apparatus for producing methane by reacting CO and H ₂ in a reaction chamber have been proposed. This method not only increases the size of the apparatus due to low methane production efficiency, but also requires an additional purification step because the sulfuric acid in the coal is mixed into the produced gas.

[0004]

SUMMARY OF THE INVENTION The above-mentioned synthetic natural gas producing apparatus is inefficient, and it has not been possible to mass-produce synthetic gas at low cost on a commercial or industrial scale. Moreover, since a large amount of sulfuric acid is contained in the produced gas because coal powder is used as a raw material, clean synthetic natural gas cannot be provided.

It is an object of the present invention to provide a method and apparatus for producing clean synthetic natural gas at low cost.

Another object of the present invention is to provide a method for producing synthetic natural gas and an apparatus therefor which enable mass production of low-cost, clean synthetic natural gas on a commercial or industrial scale using inexpensive water as a raw material. With the goal.

[0007]

Means for Solving the Problems In the first invention of the present application, a synthetic natural gas producing apparatus includes a housing means having an inlet means for introducing synthetic gas and an outlet for discharging methane-rich gas, and a first plasma supported in the housing means. An electrode means, a second plasma electrode means spaced from the first plasma electrode means, a plasma reaction chamber formed between the first and second plasma electrode means, and a plasma reaction chamber. A methanation catalyst that produces methane from synthesis gas in the presence of a plasma;
Power supply means for supplying power to the first and second plasma electrode means to generate plasma in the plasma reaction chamber, cooling means for cooling the first and second electrode means inside the housing means, and connecting the inlet and the arc reaction chamber. And a passage means.

In the second invention of the present application, the synthetic natural gas production method comprises the steps of arranging a plasma reaction chamber having plasma electrode means in a housing means, and filling the plasma reaction chamber with a methanation catalyst for producing methane from synthesis gas. And generating electricity in the plasma reaction chamber by supplying power for plasma generation to the plasma electrode means, and supplying synthesis gas into the plasma reaction chamber and contacting the synthesis gas with the methanation catalyst in the presence of the plasma. And a step of reacting.

In the third invention of the present application, a step of disposing a plasma reaction chamber having a plasma electrode means in a housing means, a step of supplying power to the plasma electrode means to generate plasma in the plasma reaction chamber, Introducing a synthesis gas containing hydrogen and carbon monoxide to directly react hydrogen and carbon monoxide in the presence of plasma to produce methane.

[0010]

According to the method and the apparatus for producing synthetic natural gas of the present invention, a plasma electrode means and a plasma reaction chamber are arranged in a housing means having an inlet for introducing synthetic gas and an outlet for discharging synthetic natural gas. The synthesis gas is introduced into the plasma reaction chamber while generating the gas, thereby enabling mass production of the synthesis natural gas composed of methane with high efficiency from the synthesis gas.

[0011]

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 and 2, the synthetic natural gas producing apparatus 10 includes a front cover 12, a front housing 14, a center housing 16 and a rear housing 18. Housings 14, 16, 18
Are made of ceramic and other heat-resistant insulating materials, respectively.
It has a common central shaft 20 and is connected by screws (not shown). For example, in FIG. 2, the screw passes through the through hole 21 of the center housing 16 and is screwed into a tap hole of the rear housing 18. In FIG.
Inside the housings 18, 16, and 14, a plasma cathode holder 22, an injector ring 24, and a plasma anode 26 are housed. The plasma cathode holder 22 is fixedly supported inside the housings 18 and 16. The injector ring 24 is sandwiched between the cathode holder 22 and the anode 26 in the center housing 1.
6 is fixedly supported inside. The rear portion of the anode 26 extends partially into the center housing 16 and is held in a fixed position by the front cover 12.

The cathode holder 22 and the anode 26 are connected to an AC power source, a DC power source, or a high-frequency pulse power source (not shown) via terminal members 28 and 30, respectively.
The terminal member 28 is screwed to the cathode holder 22, and the terminal member 30 is screwed to the tap hole 14 a of the front housing 14 so as to conduct with the anode 26. The housing 14 and the front cover 12 are respectively provided with a synthetic gas inlet 32 and a synthetic natural gas outlet 3.
4 is provided. The inlet 32 is a "syngas production apparatus" (Japanese Patent Application No. 11-243,653) by the same applicant as the present application.
H ₂ / CO mixed gas is supplied continuously. Inside the housings 14 and 16, there are provided first cooling passage means 38 for cooling the outer periphery of the anode 26, second cooling passage means 40 for cooling the cathode holder 22, and an intermediate passage 41.

In FIG. 2, a plasma cathode holder 2
2 has a front end 46 for holding a screw portion 44 of the plasma cathode assemble 42. Cathode assembly 42 includes a bar-shaped cathode 48 that extends inside anode 26. The anode 26 and the cathode 48 are made of an electrode material such as thorium-containing tungsten or hafnium nitride. The central part of the cathode holder 22 is
And a cooling unit 50 disposed therein. The cooling unit 50 has a central hole 52 in the cathode holder 22 and a tubular copper mesh 54.
And a plurality of pellet or ball-shaped solid heat conductors 56 filled in the copper mesh 54 for dissipating the heat of the cathode assemble 48. The second cooling passage means 40 includes an annular passage 58, an inlet 60, and an outlet 62 formed in the cathode holder 22. Annular passage 5
8 communicates with the first cooling passage means 38. A gas supply passage 64 is arranged between the outlet 62 and the injector ring 24. The gas supply passage 64 is formed in the rear housing 18, and a flow control valve 66 for adjusting the supply amount of the synthesis gas is disposed at an intermediate portion thereof. The center housing 16 has a passage 68 for supplying steam to the injector ring 24. An annular passage 70 is formed between the outer periphery of the injector ring 24 and the inner wall of the center housing 16. The injector ring 24 includes a plurality of gas injection nozzles 72 for injecting synthesis gas in a tangential direction, and a vortex chamber 74 is formed between an inner wall thereof and an outer periphery of the cathode assembly 42.

A plasma reaction chamber 76 is formed between the plasma cathode assembly 42 and the plasma anode 26,
A methanation catalyst 78 made of a particulate carbon-containing material is filled therein. The carbon-containing material 78 has a diameter of 3 to 1 in which carbon is condensed.
It is composed of 0 mm carbon balls or graphite balls. Note that the carbon-containing material 78 may be one obtained by depositing carbon on the surface of the catalyst metal. As an example, the catalyst metal may be used alone or nickel-containing magnetite (Fe ₃ O ₄ )
Or the like may be selected from iron oxides, and then activated by passing hydrogen at 300 to 500 ° C. to form oxygen-deficient magnetite, and then introducing carbon dioxide to deposit carbon on the magnetite surface. In FIG. 2, the carbon balls are in point contact with each other in the plasma reaction chamber 76, and a number of gaps are formed between the carbon balls. Therefore, when power is supplied to the plasma electrode, current flows through each carbon ball,
A plasma arc is generated by the spark in the gap. This plasma arc is uniformly generated in most of the gaps of the carbon ball filled in the plasma reaction chamber 76. The synthesis gas introduced from the injector ring 24 passes through these gaps. At this time, the mixed gas of CO and hydrogen is brought into contact with carbon balls or carbon of nickel-containing magnetite in the presence of a plasma arc to produce methane represented by the following formula.

[0015]

Embedded image CO + 3H ₂ → CH ₄ + H ₂ O

A disk-shaped perforated plate 80 is arranged on the front side of the plasma reaction chamber 76. A quenching chamber 82 and a quenching fin 84 are formed at the front end of the anode 26, and the quenching chamber 82 is connected to the first cooling passage unit 3 through a passage 86.
8 is connected. A quenching chamber 88 and a quenching fin 90 are formed in the center of the front cover 12. Quench room 8
The quench fins 84 and 90 and the quench fins 84 and 90 are respectively aligned and continuous in the central axis direction. Methane rich gas is perforated plate 8
After squirting from 0 and expanding, quenched by the quench fins 88 and 90, the methane is discharged from the outlet 34, and methane and water are separated by a separation device including a heat exchanger.

In the above configuration, the synthesis gas as a raw material is shared as a cooling medium. For this purpose, synthesis gas is introduced from the inlet 32 into the first cooling passage means 38, partly supplied to the quenching chambers 82, 88 via the passage 86, and the remainder via the passage 41 to the second cooling passage. Means 40
Supplied to The synthesis gas then flows into the annular passage 58 and the inlet 60 of the second cooling passage means 40 to cool the cathode holder 22 and is preheated. The flow rate of the preheated synthesis gas is adjusted by the opening adjustment screw 66, injected into the swirl chamber 74 through the injection nozzle 72, and flows into the plasma reaction chamber 76 while cooling the surface of the cathode assembly 42. At this time, the synthesis gas contacts and reacts with the carbon-containing material 78 in the plasma reaction chamber 76 in the presence of plasma to generate a methane-rich gas. The methane-rich gas is ejected from the perforated plate 80, quenched by the quench fins 84 and 90, and then discharged from the outlet 34.

In the first modified example of FIG. 2, a ball-shaped granular electrode body made of the same material as the plasma electrode is filled in the plasma reaction chamber 76 instead of the carbon-containing material 78, and a plasma arc is formed in the gap between the granular electrode bodies. Occurs. Therefore, when the synthesis gas passes through the gap of the granular electrode, radicals of CO and H ₂ are generated in the presence of the plasma, and these are directly combined, and the methanation reaction proceeds according to the above equation. In the first modification, when the plasma electrodes 26 and 48 are connected to a high-frequency pulse power supply that applies a voltage of 20 to 30 eV in pulses of 10 to 50 kHz, cold (non-equilibrium) plasma is generated in the plasma reaction chamber 76. , CO
And H ₂ are exposed to electrons and ions by the plasma and excited, and methanation proceeds. In this modification, a solid methane conversion catalyst formed by condensing a metal catalyst into a pellet or a ball instead of a granular electrode body is replaced with a plasma reaction chamber 76.
It may be filled inside. Metal catalysts are described, for example, in U.S. Pat. Nos. 4,238,371, 4,211,718, 4,368,142 and 4,666,881.
May be disclosed.

FIG. 3 shows a modification of the synthetic natural gas production apparatus of FIG. 2, and the same parts as those of FIG. 2 are denoted by the same reference numerals. In FIG. 3, an anode 100 is a multi-phase plasma electrode 10 comprising a tubular three-phase AC electrode concentric with a plasma cathode 48.
2, 104, and 106, which are connected to the R, S, and T phases of the three-phase AC power supply 108, respectively. The cathode holder 42 is preferably connected to the neutral point of the three-phase AC power supply 108 or has a ground potential. The electrode 106 is a quenching chamber 11
0 is provided. An insulating spacer 112 is disposed between the plasma electrodes 102 and 104, and similarly, an insulating spacer 114
Is disposed between the plasma electrodes 104 and 106. When a three-phase AC voltage is supplied to the multiphase plasma electrodes 102, 104, and 106, the multiphase electrode 10
2, 104 between the neutral electrode 48 and the granular carbon-containing material 78
A plasma arc is generated in the gap. Next, at the second timing, a potential difference occurs between the multi-phase electrodes 102, 104, 106 and the neutral electrode 48, and a plasma arc is generated in a gap between the particulate carbon-containing material 78 therebetween.
At the third timing, a potential difference is generated between the multi-phase electrodes 102 and 106 and the neutral electrode 48, and a plasma arc is generated in a gap between the particulate carbon-containing material 78 therebetween.
At the fourth timing, all the multi-phase electrodes 102, 10
4, the granular carbon-containing material 78 between the neutral electrode 48
A plasma arc is generated in the gap. At the fifth timing, a plasma arc is generated in a gap between the particulate carbon-containing material 78 between the multi-phase electrodes 104 and 106 and the neutral electrode 48. At the sixth timing, the multi-phase electrodes 102, 1
A plasma arc is generated in the gap of the particulate carbon-containing material 78 between the neutral electrode 04 and 106 and the neutral electrode. Thereafter, the same cycle is repeated. As described above, in the plasma reaction chamber 76, the arc generation position is sequentially changed according to the voltage phase, and the ionized gas at a plurality of arc generation positions is constantly supplied. The three-phase AC power supply 108 may be constituted by a high-frequency AC power supply having an output frequency of 5 to 50 kHz. The neutral electrode 4
8, the multi-phase electrodes 102, 104, and 106 may be connected to a three-phase AC power supply having a delta (Δ) connection, and the arc generating position may be changed at a plurality of points along the three-phase AC voltage. .

FIG. 4 shows another modification of the synthetic natural gas producing apparatus of FIG. 2, and the same parts as those of FIG. 2 are denoted by the same reference numerals. In FIG. 4, the first electrode is a front housing 1.
4 (see FIG. 2), a flat cathode 122 supported by the cathode holder 42, and an anode 120
And the cathode 122 and the front housing 1
4 and an insulating sleeve 124 housed in the center housing 16. The anode 120 is connected to the cooling medium passage 1
26, a quenching chamber 128, a quenching fin 130, and a product gas outlet 132. Cathode 122 is gas supply port 1
And the swirl chamber 74 of the injector ring 24
Communicate with A plasma reaction chamber 76 is formed inside the insulating sleeve 124, and is filled with the particulate carbon-containing material 78. When power is supplied to the anode 120 and the cathode 122, a plasma arc is generated in the gap of the carbon-containing material 78. The synthesis gas is supplied from the vortex chamber 74 to the gas supply port 134 of the cathode 122.
When introduced into the plasma arc reaction chamber 76 through
Synthesis gas passes through the gap of the carbon-containing material 78, then, CO and H ₂ in the presence of carbon of the carbon-containing material 78 to produce a mixed gas of the reaction to methane and water vapor. The mixed gas is quenched by the quench fin 130 while being ejected from the ejection port 132, discharged from the outlet 136, and further cooled in the next step to separate methane and H ₂ O. In FIG. 4, a second plate-like electrode having a through hole is disposed between the anode 120 and the cathode 122, and these electrodes are connected to a three-phase AC power supply or a high-frequency AC power supply as in the embodiment of FIG. Is also good.

In the embodiment of FIG. 3, the neutral electrode 48 may be omitted. Further, the three-phase AC electrode may be a four-phase AC four electrode or a six-phase AC six electrode. 3 and 4, instead of the carbon-containing material 78, a solid methanation catalyst or a granular electrode body is filled in the plasma reaction chamber 76, and the plasma electrode is connected to a high-frequency pulse power supply to connect the plasma reaction chamber 76. A cold plasma may be generated inside.

[0022]

As is apparent from the above, according to the method and apparatus for producing synthetic natural gas of the present invention, it is possible to mass-produce synthetic natural gas at low cost by using synthetic gas generated from water and carbon as raw materials. It contributes greatly as a new energy source or as a raw material for the chemical industry.

[Brief description of the drawings]

FIG. 1 is an external view of a synthetic natural gas production apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a sectional view of the synthetic natural gas production apparatus of FIG.

FIG. 3 is a modified example of the synthetic natural gas production apparatus of FIG.

FIG. 4 is another modified example of the synthetic natural gas production apparatus of FIG.

[Explanation of symbols]

12 Front cover, 14 Front housing, 16 Center housing, 18 Rear housing, 20 Center shaft, 22 Cathode holder, 24
Injector ring, 26 plasma anode, 28,
30 terminal member, 32 inlet, 34 outlet, 38 first cooling passage, 40 second cooling passage,
42 Cathode assemble, 48 Plasma cathode, 5
0 cooling unit, 72 jet nozzle, 74 vortex chamber, 7
6 plasma reaction chamber, 78 methanation catalyst, 82, 8
8 quench chamber, 102, 104, 106 tubular three-phase AC electrode, 108 three-phase AC power supply, 110 quench chamber, 1
22 flat plate plasma cathode, 126 plasma anode

Claims (17)

[Claims] 1. A housing means having a syngas introduction inlet means and a methane-rich gas discharge outlet, a first plasma electrode means supported in the housing means, and spaced from the first plasma electrode means. A second plasma electrode means, a plasma reaction chamber formed between the first and second plasma electrode means, and a methanation catalyst filled in the plasma reaction chamber to generate methane from synthesis gas in the presence of plasma; First and second
An apparatus for producing synthetic natural gas, comprising: a plasma power supply means for supplying plasma electrode means to generate plasma in a plasma reaction chamber; and a passage means connecting the inlet means and the plasma reaction chamber. 2. The synthetic natural gas producing apparatus according to claim 1, wherein the passage means includes a cooling means. 3. The synthetic natural gas production apparatus according to claim 1, further comprising an electrode holder accommodated in the housing means and supporting the second plasma electrode means. 4. The synthetic natural gas production apparatus according to claim 3, wherein the electrode holder includes a cooling unit, and the cooling unit is connected to the passage means. 5. The synthetic natural gas producing apparatus according to claim 4, further comprising an injector for supplying the synthesis gas to the plasma reaction chamber. 6. The synthetic natural gas production apparatus according to claim 3, wherein the first plasma electrode means comprises a tubular anode, and the second plasma electrode means comprises a cathode assemble supported by an electrode holder and concentric with the tubular anode. 7. A combination according to claim 1, wherein the first and second plasma electrode means comprise tubular three-phase AC electrodes spaced apart in the axial direction, and the plasma power supply means comprises a three-phase AC power supply. Natural gas production equipment. 8. The synthetic natural gas production apparatus according to claim 7, further comprising a neutral electrode extending into the tubular electrode, wherein the neutral electrode is grounded. 9. The method according to claim 3, wherein the first plasma electrode means comprises an anode, and the second plasma electrode means comprises a flat cathode which is axially spaced from the anode and supported by an electrode holder. Synthetic natural gas production equipment. 10. The method according to claim 1, further comprising:
An apparatus for producing synthetic natural gas, comprising: a front cover fixed to a housing means; and a quenching means in which the front cover is disposed at an outlet. 11. The method according to claim 4 or 5, further comprising:
An apparatus for producing synthetic natural gas comprising a flow rate adjusting means between a cooling unit and an injector means. 12. A step of disposing a plasma reaction chamber having plasma electrode means in a housing means, a step of filling a methanation catalyst for producing methane from synthesis gas in the plasma reaction chamber, and a step of generating plasma in the plasma electrode means. A synthetic natural gas comprising: a step of supplying plasma power to generate plasma in a plasma reaction chamber; and a step of supplying a synthesis gas to the plasma reaction chamber to cause a reaction of the synthesis gas with a methanation catalyst in the presence of the plasma. Manufacturing method. 13. The synthetic natural gas production method according to claim 12, further comprising a step of quenching the methane. 14. The synthetic natural gas production method according to claim 12, wherein the methanation catalyst comprises a particulate carbon-containing material and the plasma comprises a plasma arc. 15. The synthetic natural gas production method according to claim 12, wherein the methanation catalyst comprises a metal catalyst and the plasma comprises cold plasma. 16. A step of disposing a plasma reaction chamber provided with a plasma electrode means in a housing means, a step of supplying power to the plasma electrode means to generate plasma in the plasma reaction chamber, and a step of supplying hydrogen and monoxide in the plasma reaction chamber. Introducing a synthesis gas containing carbon and directly reacting hydrogen and carbon monoxide in the presence of plasma to produce methane. 17. The method for producing synthetic natural gas according to claim 16, further comprising a step of disposing a granular electrode material in the plasma reaction chamber and passing a synthetic gas while generating plasma in a gap between the granular electrode materials.