JP2002327186A - Method for producing substitute natural gas and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both a method for producing a substitute natural gas by which the clean substitute natural gas can be mass-produced at a low cost by using inexpensive water and an inexpensive carbon material as raw materials and an apparatus for producing the substitute natural gas. SOLUTION: A plasma gas composed of steam is subjected to a contact reaction with a solid carbon material at a high temperature in a synthesis gas-producing part 34B of a thermal plasma reactor PR to thereby produce the synthesis gas. The resultant synthesis gas is then subjected to a methanation reaction in a methanation reactor MR to produce a methane-rich gas, which is cooled to separate condensed water. The resultant condensed water is converted into steam to produce the substitute natural gas SNG while circulating the steam as a plasma gas through the synthesis gas-producing part 34B. The H2 /CO ratio is regulated to a prescribed value by controlling an arc current of arc electrodes 36, 38 and 40 with a controller 106.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing alternative natural gas (hereinafter abbreviated as SNG) and an apparatus for producing the same, and particularly to a method for producing a clean alternative natural gas containing no sulfur and an apparatus therefor. About.

[0002]

2. Description of the Related Art In recent years, the use of natural gas has been rapidly expanding as a key to preventing global warming due to carbon dioxide emission.
Mining natural gas involves significant investment and environmental destruction, increasing the environmental burden and requiring a long time to recover investment costs. In addition, since natural gas is linked to the international price of crude oil, the price has become unstable, and the natural gas price has been maintained at a high value and its spread has been delayed.

[0003] Thus, US Pat.
No. 3 and JP-A-8-127,544 propose a method for producing methane, which is a main component of SNG, using carbon dioxide and hydrogen as raw materials. However, since carbon dioxide and hydrogen as raw materials of SNG are extremely high, SNG cannot be produced at low cost.

Japanese Patent Application Laid-Open No. 2000-53,978 proposes a method for producing SNG from a hydrocarbon-containing material selected from hydrocarbons and lower alcohols as a raw material.
In this SNG production method, carbon is deposited on the catalyst surface during the methanation reaction, and the reaction deteriorates. For this reason, SNG cannot be continuously produced. Moreover, since the raw material cost is high, the production cost of SNG cannot be reduced.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a production method capable of stably mass producing low-cost alternative natural gas at a low cost using inexpensive water and an inexpensive carbon material as raw materials, and an apparatus therefor. The purpose is to:

[0006]

According to a first concept of the present invention, an alternative natural gas production method comprises providing a thermal plasma reactor having a thermal plasma reaction chamber and an arc electrode disposed in the thermal plasma reaction chamber. Filling a solid carbon material into a thermal plasma reaction chamber to form a minute arc passage in a gap between the solid carbon materials; supplying plasma power to an arc electrode to generate thermal plasma in the minute arc passage; Generating a thermal gas while passing a plasma gas composed of water vapor into the minute arc passage to cause a contact reaction between the plasma gas and the carbon of the solid carbon material to generate a synthesis gas containing H ₂ and CO. process and that; by controlling the thermal plasma temperature arc current of the arc electrode variable to a step of adjusting the H 2 _/ CO ratio above a predetermined value; methanation reactor Synthesizing the water-containing methane-rich gas by contacting the synthesis gas of the predetermined value with the methanation catalyst; cooling the methane-rich gas to separate and recover the first condensed water from the methane-rich gas; And supplying the plasma gas as the plasma gas into the minute arc passage.

According to a second aspect of the present invention, an alternative natural gas production method comprises the steps of providing a plasma reactor having a thermal plasma reaction chamber and an arc electrode disposed in the thermal plasma reaction chamber; Filling a reaction chamber with a solid carbon material to form a minute arc passage in a gap between the solid carbon material; supplying arc power to an arc electrode to generate thermal plasma in the minute arc passage; Generating H ₂ and CO-containing synthesis gas by causing thermal plasma to generate a thermal plasma while passing the plasma gas into the minute arc passage to cause contact reaction between the plasma gas and carbon of the solid carbon material; and outputting the H _2, CO detection signal by detecting the concentration of in; and step of calculating the H _{2 /} CO ratio from the detection signal and outputs the arc current control signal; arc By controlling the thermal plasma temperature by varying the arc current in response to a flow control signal, H
Adjusting the ₂ / CO ratio to a predetermined value or more; contacting the synthesis gas of the predetermined value with the methanation catalyst in the methanation reaction tank to synthesize a water-containing methane-rich gas; cooling the methane-rich gas to produce methane A step of separating and recovering the first condensed water from the rich gas; and a step of converting the first condensed water into steam and supplying it as the plasma gas into the minute arc passage.

[0008] According to a third aspect of the invention, an alternative natural gas production apparatus comprises: a thermal plasma reactor having a sealed thermal plasma reaction chamber and an arc electrode disposed in the thermal plasma reaction chamber; A carbon material supply device for supplying solid carbon material to the chamber; a raw water supply line for supplying raw water to the thermal plasma reaction chamber; and a plurality of microscopic holes formed in the thermal plasma reaction chamber and formed in gaps between the solid carbon materials. An arc passage is provided, and thermal plasma is generated in the minute arc passage in the presence of a plasma gas comprising water vapor, and H ₂ , C is generated by a contact reaction between the plasma gas and the solid carbon material.
A synthesis gas generation unit for generating an O-containing synthesis gas; a plasma power supply for supplying an arc current to the arc electrode; and a H ₂ / CO ratio of a predetermined value by controlling the arc current to vary a thermal plasma temperature. A control device for adjusting the above; a methanation reactor for synthesizing a water-containing methane-rich gas from the synthesis gas; a heat exchanger for cooling the methane-rich gas to separate and recover condensed water from the methane-rich gas; A condensed water reflux line for refluxing to the plasma reaction chamber.

[0009]

According to the method and apparatus for producing a natural gas alternative of the present invention, water vapor is supplied as a plasma gas into a minute arc passage formed in a gap between solid carbon materials in a synthesis gas generating section in a thermal plasma reaction chamber. Then, while generating thermal plasma in the minute arc passage, the water vapor and the carbon of the carbon material are contact-reacted to efficiently generate a synthesis gas containing H ₂ and CO as shown by the following equation.

C + H ₂ O → Co + H ₂
(1) Co + H ₂ O → CO ₂ + H ₂ (2)

Next, the synthesis gas obtained by the reactions (1) and (2) is then fed to a methanation tank where it reacts with the methanation catalyst and reacts with the SNG comprising methane-rich gas as shown in the following formula. Generate

Co + 3H ₂ → CH ₄ + H ₂ O
(3) Co ₂ + 4H ₂ → CH ₄ + 2H ₂ O (4)

As shown in the above reaction formulas (3) and (4), the methane-rich gas contains product water as a by-product. In the present invention, the product water is separated and condensed from the methane-rich gas and recovered as condensed water. This is used as a plasma gas raw material by refluxing it to the steam generation section on the upstream side of the thermal plasma reaction chamber, reducing the environmental load without discharging wastewater to the outside, and at the same time, lowering the raw material cost, resulting in extremely low cost. Enables mass production of alternative natural gas.

[0014]

Hereinafter, an alternative natural gas producing apparatus according to a preferred embodiment of the present invention will be described with reference to the drawings. In FIG. 1, an alternative natural gas producing apparatus 10 includes a carbon raw material input apparatus 12 for supplying a solid carbon material,
A raw water supply line 11, a water supply pump P1 for supplying raw water to the raw water supply line 11, a flow control valve 13 for adjusting a flow rate of the raw water, a thermal plasma reactor PR for generating synthesis gas, and a thermal plasma reactor A temperature sensor T1 for detecting the temperature of the thermal plasma reaction chamber of the PR and outputting it as a temperature signal, a syngas recirculation line 15 for recirculating a part of the synthesis gas, and a flow control valve 17 for adjusting the recirculation amount of the synthesis gas
A first heat exchanger H1 for exchanging heat between the raw water and the synthesis gas to preheat the raw water, a cooler C1 for cooling the synthesis gas, an on-off valve V1, and separating water vapor from the synthesis gas. A first steam-water separator S1 for collecting and producing condensed water;
A condensed water reflux line 19 that joins the raw water supply line 11 from the bottom of the steam separator S1, a circulation pump P2 that circulates the condensed water through the condensed water supply line 11 to the thermal plasma reactor PR, A first level sensor L1 disposed in the separator S1 for detecting the level of condensed water and outputting a level signal; and a hydrogen concentration in the first steam-water separator S1 for detecting hydrogen concentration and CO concentration, respectively. a hydrogen sensor _{H 2} S and carbon monoxide sensor COS for outputting a detection signal and CO concentration detection signal, the synthesis gas 15 to 50
Compressor CM for pressurizing in the range of kg / cm ²
And a pressure sensor PS for detecting the pressure of the synthesis gas and outputting a pressure signal, a methanation reaction tank MR filled with a methanation catalyst to generate a methane-rich gas, and a heating medium supplied to the methanation reaction tank MR. Heat exchanger 100 for heating to a reaction temperature of 250 to 500 ° C., a temperature sensor T2 for detecting the temperature of the methanation reaction tank MR and outputting a methanation reaction temperature signal, and a second temperature sensor for cooling the methane-rich gas. (2) a heat exchanger H2, a cooler C2 for further cooling the methane-rich gas, an expansion valve V2, a second steam-water separator S2 for separating and recovering alternative natural gas SNG and by-product water from the methane-rich gas, A gas flow rate sensor 102 for detecting the flow rate of natural gas and outputting an SNG flow rate detection signal; and a condensed water of the second steam / water separator S2, and a raw water supply line 1 Condensed water reflux line 21 to be combined with the
And a branch valve V3 for branching a part of the SNG
, A power generator EG driven by SNG, a current controller 104 for varying the supply voltage to control the supply power of the thermal plasma reactor PR, and an earthquake sensor 105. Temperature detection signals of temperature sensors T1 and T2, first and second
Level signal of the level sensor L1, L2, the hydrogen sensor _{H 2}
Hydrogen concentration detection signal of S, CO of carbon monoxide sensor COS
The concentration detection signal, the detection signal of the synthesis gas pressure of the pressure sensor PS, and the detection signals of the SNG flow sensor 102 and the earthquake sensor 105 are output to the control device 106, and the control device 106
Controls the operation of the alternative natural gas production apparatus 10 in response to these detection signals as described below.

FIG. 2 shows a specific structure of the thermal plasma reactor PR of FIG. In FIG. 2, a thermal plasma reactor PR includes a thermal plasma reactor 14 connected to a carbon feeder 12 and a plasma power supply 16 composed of a multiphase AC power supply.
And The raw material input device 12 includes a hopper 20 for storing a solid carbon material such as powdered, pelletized or massive graphite, granular activated carbon, or carbon powder, a screw feeder 22, and a rotary valve 24. The solid carbon raw material is continuously charged into 14. The thermal plasma reactor 14 includes a cylindrical outer insulating casing 26 made of a heat-resistant ceramic, and an inner insulating casing 32 having a cylindrical thermal plasma reaction chamber 34.
An insulating electrode holder 28 attached to the upper end by bolts 30 is provided. The thermal plasma reaction chamber 34 includes a water vapor generation section 34A formed on the upstream side and a synthesis gas generation section 34B formed on the downstream side. When the granular carbon material is supplied to the synthesis gas generator 34B, a large number of minute arc passages 35 are formed, and a large amount of thermal plasma due to sparks is uniformly generated in the minute arc passages. At this time, the raw water turns into steam due to high temperature in the steam generating section 34A formed on the upstream side of the plasma arc reaction chamber 34, and this steam passes through the minute arc passage 35 as a plasma gas to the downstream side, during which the steam is It reacts with the carbon of the raw material to produce synthesis gas as shown in the above-mentioned reaction formula. At this time, when the reaction temperature of the thermal plasma reaction chamber 34 is about 835 ° C., the generated gas is H ₂ , 47.8%; Co, 9.8%;
_{h 4, 16.4%; CO 2} , 13.8%; C 2 H 2,
_{2.0%; C 2 H 6,} 1.0%; O 2, 2.4%; the other hydrocarbons _{(C x H y) 2.2%} . When the reaction temperature of the thermal plasma reaction chamber 34 rises to about 1000 ° C., the generated gas is H ₂ , 75.5%; CO, 13.4%; C
O ₂ , 7.6%; CH ₄ , 2.0%; C ₂ H ₂ , 0.3
%; C ₂ H ₆ , 0.1%; O ₂ , 2.0%%;
_{The 2} / CO ratio is 5.6. Thus, the H ₂ / Co ratio in the synthesis gas can be easily adjusted by controlling the plasma temperature.

The insulated electrode holder 28 supports rod-shaped multi-phase arc electrodes 36, 38, and 40. A disk-shaped neutral electrode 42 for emitting thermoelectrons for generating thermal plasma is disposed below the insulating casing 32. The neutral electrode 42 has a conical surface 4
2a and a central opening 42b. The neutral electrode 42 is supported by an electrode holder 78 formed at the lower end of the insulating casing 26, and is fixed by bolts 80. The electrode holder 28 has a carbon material supply port 50 connected to the carbon material charging device 12. A raw water supply port 52 for introducing raw water to 34A into the steam generating section is disposed adjacent to and above the arc electrodes 36, 38, and 40 above the outer insulating casing 26. The reason is that the raw material water effectively cools the arc electrodes 36, 38, and 40 to prevent abnormal temperature rise of the arc electrodes,
This is because water vapor that functions as a plasma gas is efficiently generated from the raw water using the high temperatures of 6, 38, and 40. A cooling / exhaust heat recovery unit 63 including an annular cooling passage 54 is formed on the outer periphery of the inner casing 32 and the neutral electrode 42, and these cooling passages communicate with each other through a communication passage 64. The outer insulating casing 26 has an inlet 74 and an outlet 76, each of which communicates with the cooling passage 54, respectively. An insulating end plate 82 is fixed via a bolt 80 to an electrode holder 78 constituting a lower end portion of the insulating casing 26, and a seal member 83 is disposed between them. On the downstream side of the thermal plasma reaction chamber 34, a filter 84 is accommodated by a central opening 42b of the neutral electrode 42 and a filter accommodating portion 82a of the end plate 82, so that the synthesis gas SG passes therethrough. The end plate 82 is a synthesis gas outlet 86
Is provided.

The outlet 86 is a syngas reflux line 1
5 and the raw water supply line 11 through the flow control valve 17
Is connected to the raw water supply port 52. The raw water is preheated in the cooling unit 63 and introduced into the water vapor generating unit 34A of the thermal plasma reaction chamber 34 via the raw water supply port 52 via the outlet 76, and a plasma gas composed of water vapor is generated. At this time, a part of the synthesis gas SG of the outlet 86 is supplied from the raw water supply port 52 into the thermal plasma reaction chamber 34 via the synthesis gas reflux line 15, and the aquatic shift reaction of the above-mentioned reaction formula (2) is performed. . Code 88
Denotes a seal member.

In FIG. 2, the multi-phase arc electrodes 36, 3
Numerals 8 and 40 are three-phase AC electrodes, and polyphase AC power supply 16 is shown as a three-phase AC power supply. Neutral electrode 42 is connected to the neutral point of the three-phase AC power supply. Three-phase AC power supply 1
6 between the three-phase AC electrodes 36, 38, 40 and the neutral electrode 42, an output frequency of 50-60 Hz and an output voltage of 30-2.
Three-phase AC power of 40 V and output current of 100 to 200 A is supplied. At this time, among the three-phase AC electrodes 36, 38, and 40, a plurality of thermal plasma columns (columns) simultaneously rotate between two electrodes, three electrodes, and the neutral electrode 42.
According to the phase of the three-phase alternating current, the generation positions of the plurality of thermal plasma columns are continuously changed to uniformly heat the solid carbon material, so that the synthesis gas can be efficiently generated in the thermal plasma reaction chamber 34. generate. At this time, a large amount of ionized ions are always present in the gap between the solid carbon raw materials, and thermoelectrons are always emitted from the neutral electrode 42, so that thermal plasma is always generated stably. Part of the alternative natural gas SNG is supplied to a combustor CB of a power plant EG including a compressor and a turbine, and a generator GE is driven. Generator GE
Output power of a current control device 104 such as an inverter
To the thermal plasma reactor PR.

In FIG. 3, a control unit 106 stores a control program for controlling the operation of the alternative natural gas producing apparatus 10 of the present invention and a ROM (Read) for storing reference data.
On Memory) 110 and a CPU (Central Proc) for processing control programs and data.
(Essing Unit) 112 and a nonvolatile RAM (Random Access) for storing conditions and values set therein and input information from various sensors.
ss Memory) 114. CPU112
Is set flow rate, set temperature, set pressure or set H ₂ / C
An input device 1 having a numeric keypad for setting and inputting input information such as an O ratio, a start key for instructing start of plant operation, and the like.
16 and temperature sensors T1, T2, hydrogen concentration sensor H
₂ S, CO concentration sensor COS, level sensors L1, L
2. The SNG flow sensor 102, the pressure sensor PS, and the earthquake sensor 105 are connected, and various detection signals are input as input signals. The CPU 112 outputs these input signals to R
The OM 110 compares the respective reference signals stored in the OM 110 with each other and outputs various command signals in accordance with their differences, and outputs these command signals to the heat exchanger 100, the current control device 104, the flow control valve 13,
17 and the pumps P1 and P2. Display unit 110
Is composed of a display panel such as a liquid crystal, and has a detection pressure,
Detection temperature, H ₂ concentration, CO concentration, H ₂ / CO ratio and S
Various information such as NG flow rate is displayed. Display drive circuit 10
Reference numeral 8 controls switching of information displayed on the display unit 110.

The input device 116 includes a start switch (not shown), an optimum temperature of the thermal plasma reactor 14 and an optimum temperature of the methanation reactor MR, and an optimum H _{2 of the} synthesis gas SG.
A key switch (not shown) is provided for setting and inputting various reference data such as a / CO ratio, a target pressure of the compressor CM, a level value L1, L2 of the condensed water, a target flow rate of the SNG, and a target earthquake level value. The temperature sensor T1 indirectly detects the temperature of the thermal plasma reaction chamber 34 via the inner casing 32 and outputs a temperature signal T1. The temperature sensor T2 detects the temperature of the methanation reaction tank MR and outputs a temperature signal T2. The hydrogen concentration sensor H ₂ S is a first steam-water separator S1
Detects the hydrogen concentration in the synthesis gas in the reactor and generates a hydrogen concentration signal H ₂
S is output, and the CO concentration sensor COS outputs CO in the synthesis gas.
The concentration is detected and a CO concentration signal COS is output. The level sensors L1 and L2 are first and second steam-water separators S, respectively.
1 and S2 to detect the level of each condensed water and output level signals L1 and L2, respectively. Pressure sensor PS
Detects the pressure of the synthesis gas at the outlet side of the compressor CM and outputs a pressure signal PS. SNG flow sensor 102
Detects the flow rate of the alternative natural gas SNG and outputs an SNG flow rate detection signal. The earthquake sensor 105 includes a vibration sensor, detects a vibration when a large-scale earthquake occurs, and outputs a vibration signal.

FIG. 4 shows a schematic flow diagram illustrating the basic sequence of operations for performing control of the controller of FIG. 3 in accordance with the alternative natural gas production method of the present invention. Less than,
The basic sequence will be described with reference to FIGS. 1, 3, and 4. At the time of starting, that is, when the start key is pressed, the power of the alternative natural gas producing apparatus is turned on. At this time, the heat medium of the heat exchanger 100 is supplied to the methanation reaction tank MR and is heated. In step S102,
The temperature of the methanation reaction tank MR is detected by the temperature sensor T2. If the detected temperature has reached 250 ° C., the process proceeds to step 104, and if not, the process returns to step 100. In step 104, plasma power is supplied to the thermal plasma reactor PR. Next, in steps 106 and 108, the rotor re-feeder 24 and the pump P1 are activated, respectively, to supply solid carbon material and raw water into the thermal plasma reactor PR. You. At this time, in the thermal plasma reactor PR, the raw water is converted into steam in the steam generating section 34A, and while the steam passes as a plasma gas in the fine plasma passage of the solid carbon material, the steam is converted into a steam in the presence of thermal plasma. Synthetic gas SG by contact reaction with material
Is generated. In step 110, the temperature signal T1
Is determined by the CPU 112 in FIG. 3 to be higher than or equal to the reference temperature of 1000 ° C.
The process proceeds to step 114, and in the case of No, the process proceeds to step 114.
In step 112, reflux is started using H ₂ / CO gas as an assist gas for the plasma gas. In step S 114, the output current or the output voltage is increased by the current control device 104 to increase the arc current, and the process returns to step 106. Increasing the arc current increases the H ₂ / CO ratio because the thermal plasma temperature increases. In step 112, when the assist gas is supplied to the thermal plasma reactor PR, CO, CO ₂ and steam in the generated gas SG cause an aqueous reaction. In step 114, the compressor CM is started to compress the synthesis gas SG of the first steam separator S1. At step 116, the pressure signal PS is compared with the reference pressure of 15 kg / cm ^{2 by} the CPU 112 of FIG. 3, and if the pressure has reached the reference pressure, the process proceeds to step 118; In step 118, the CPU
At 112, the hydrogen concentration signal H ₂ S and the CO concentration signal CO
Then, the H ₂ / CO ratio is calculated from this and compared with the reference H ₂ / CO ratio. If the H ₂ / CO ratio is 3 or more, the process proceeds to step S120, and if NO, the process returns to step S100. In step S120, the opening degree of the flow control valve 17 is reduced, and the H ₂ / CO reflux amount is reduced. Step 1
At 22, the level signals L1 and L2 of the condensed water are compared with the respective reference level values. If YES, the process proceeds to step 124, and if NO, the process returns to step 100.
In step 124, since the pump P1 is stopped and the supply of the raw water is stopped, and the pump P2 is started, the condensed water of the first and second steam separators S1 and S2 flows through the condensed water reflux lines 19 and 21. The raw water is circulated through the raw water supply line 11 to the thermal plasma apparatus PR. In step 126, the SNG flow rate is compared with the reference SNG flow rate by the CPU 112, and if these data match, the flow proceeds to step 12.
Then, the process returns to step 114 if NO. In step 128, the operation of the alternative natural gas production plant is continued. Next, when the power supply off switch of the input device is turned on, or when the vibration of the earthquake sensor 105 is repeated for a predetermined value or more under a predetermined condition, an operation stop command signal is output from the CPU 112, and the operation of the manufacturing plant is stopped.

Next, the operation of the alternative natural gas producing apparatus 10 shown in FIG. 1 will be described. In FIG. 1, first, the heat exchanger 1
00 and start the methanation reactor MR at 250 to 500 ° C.
The screw feeder 22 and the rotary valve 2 are heated while supplying plasma power to the arc electrode.
4 is driven to fill the thermal plasma reactor PR with a carbon material such as granular activated carbon to a predetermined level. Next, the raw water supply pump P1 is driven to supply raw water from the raw water supply port 52 to the steam generator 34A of the thermal plasma reaction chamber 34,
Then, a plasma gas composed of water vapor is generated by the high temperature. The plasma gas flows into the downstream side through a large amount of the small plasma passage 35, and generates a synthesis gas having an H ₂ / CO ratio of 3 or more while contacting and reacting with the solid carbon material at about 1000 ° C. The synthesis gas SG is supplied from the outlet 86 to the first cooler H
1 and then cooled from 60 ° to 90 ° C. in a water-cooled cooler C1, and water is separated as condensed water from the synthesis gas SG in a steam-water separator S1 via an on-off valve V1. When the condensed water reaches the level L1, the condensed water joins the raw water supply line 11 via the circulation line 19 by the pump P2, is mixed with the raw water, and is preheated in the cooling unit 63 of the thermal plasma reactor PR. It is fed to the mouth 52.
On the other hand, the synthesis gas SG is 15 to 50K with the compressor CM.
After being pressurized to g / cm ^2, it is introduced into the methanation reactor MR. The reactor MR is maintained at 250 ° to 500 ° C. by the heat exchanger 100, and the methanation catalyst is a known nickel catalyst or USP 4,238,371, USP
No. 4,368,142, US Pat. No. 4,774,261 or JP-A-5-184925 are used. The methane-rich gas is cooled by the second heat exchanger H2 and the cooler C2, and is separated and recovered into SNG and condensed water by the steam separator S2 via the pressure reducing valve V2. The condensed water is mixed with the raw water by the circulation line 21 and the circulation pump P2, and is reused in the above-described cycle.

According to the alternative natural gas production method and apparatus of the present invention, the following features are provided with respect to the above-described conventional technology. (1) Since the SNG raw material uses extremely inexpensive water and inexpensive carbon material, the cost of the raw material is significantly reduced, and the cost of the SNG can be significantly reduced. (2) Since a large amount of synthesis gas is efficiently generated using a small, high-performance thermal plasma reactor, SNG
High production efficiency. (3) Since all carbon materials are used only for syngas generation and are not used as fuel for combustion in the reformer, the utilization efficiency of raw materials is extremely high. (4) Since the thermal plasma reactor has a higher operating temperature (about 1000 ° C.) than the conventional combustion reformer, the utilization efficiency of the carbon material and water is increased, and the average plasma in the thermal plasma reaction chamber is increased. Depending on the temperature, H ₂ /
Since the CO ratio can be controlled, it is easy to optimize the operation control of the SNG manufacturing plant. (5) The conventional method requires a complicated process of periodically interrupting the synthesis gas generation process and supplying air to the reformer to burn the hydrocarbon fuel, but the method and apparatus of the present invention require these complicated processes. Since a simple process is not required, the operation control of the SNG manufacturing plant is extremely simplified, and the operation cost can be greatly reduced. (6) In the prior art, since the reformer employs a combustion system, it is difficult to control the operating temperature of the reformer with a high-speed response according to the operating conditions of the SNG manufacturing plant. According to the present invention, since the temperature of the reformer can be instantaneously controlled only by changing the supply voltage to the arc electrode, the temperature responsiveness of the reformer is high and efficient mass production of SNG is possible. Becomes (7) In the prior art, the water generated during SNG purification is discarded outside the device, which increases the environmental load, and
The cost of environmental measures is a factor that increases the cost of SNG. In the present invention, since water produced as a by-product at the time of SNG purification is recycled as a raw material, the environmental burden is extremely reduced and the raw water cost can be significantly reduced. (8) In the reforming process employing the conventional combustion method, it takes a long time to start up and stop the operation of the SNG production plant, but in the method of the present invention, the power supply to the arc electrode is cut off and the pump is turned off. It is possible to start up and stop the operation of the SNG manufacturing plant instantaneously only with it alone, and it is extremely safe especially in the event of an earthquake or other emergency countermeasures, which is advantageous for safety measures to the local residents. (9) Manufacturing with the conventional method The overall equipment size is very large and the operating costs are high, so the investment in the manufacturing plant is very large, which makes it difficult to recover the investment.
On the other hand, the manufacturing apparatus of the present invention is small, compact,
High performance and simplified manufacturing processes allow for a short return on investment.

In the above embodiment, the description has been made assuming that the thermal plasma reactor supplies the raw water from the upstream and takes out the synthesis gas from the synthesis gas outlet provided downstream.
When the amount of slag generated is large depending on the type of carbon material, a raw water supply port may be provided downstream of the reactor, and a synthesis gas outlet may be provided upstream of the reactor to separate slag and synthesis gas by a cyclone. Although the thermal plasma reactor is described as using a rod-shaped three-phase AC electrode, a three-phase AC electrode is axially spaced apart from a cylindrical electrode, and a rod-shaped neutral electrode placed at the center of the cylindrical electrode. You may comprise by an electrode.

[0025]

As is clear from the above, according to the alternative natural gas production method and the alternative natural gas production apparatus of the present invention, it is possible to mass-produce an extremely low cost and clean alternative natural gas, and Has a very high contribution. Moreover, according to the present invention, there is no emission of harmful substances such as wastewater, so that the environmental load is extremely small. Furthermore, since water and carbon materials, which are the raw materials for alternative natural gas, can be procured for an extremely long period of time, stable supply of alternative natural gas at low cost is possible without being affected by the rise in international crude oil prices. It is more advantageous. The device of the present invention is small,
Because of its compactness and high performance, it is possible to install an alternative natural gas production plant adjacent to the consuming area,
The transportation cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 shows a schematic diagram of an alternative natural gas production apparatus according to a preferred embodiment of the present invention.

FIG. 2 shows a cross-sectional view of the thermal plasma reactor of FIG.

FIG. 3 shows a schematic block diagram of the control device of FIG. 1;

FIG. 4 is a flow diagram showing a basic sequence of control by the control device of FIG. 3;

[Explanation of symbols]

11 raw water supply line, 12 carbon material input device, 1
9,21 Condensate circulation line, 24 rotary valve,
PR thermal plasma reactor, H1 first heat exchanger, S1
Steam separator, CM compressor, MR methanation reactor, H2 second heat exchanger, V2 pressure reducing valve, S2 second
Steam separator, P1 raw water supply pump, P2 circulation pump, EG generator, 100 heat exchanger

Claims (11)

[Claims] A step of preparing a thermal plasma reactor having a thermal plasma reaction chamber and an arc electrode disposed in the thermal plasma reaction chamber; Forming a minute arc passage in the gap between the materials; supplying plasma power to the arc electrode to generate thermal plasma in the minute arc passage; and performing heat while passing a plasma gas comprising water vapor through the minute arc passage. Generating a H ₂ , CO-containing synthesis gas by generating a plasma to cause a contact reaction between the plasma gas and the carbon of the solid carbon material; and controlling the thermal plasma temperature by varying the arc current of the arc electrode. Gives H ₂ /
A step of adjusting the CO ratio to a predetermined value or more; a step of contacting the synthesis gas of the predetermined value with the methanation catalyst in the methanation reaction tank to synthesize a water-containing methane-rich gas; A method for producing a natural gas alternative, comprising: separating and collecting the first condensed water; and converting the first condensed water into steam and supplying the same as the plasma gas into the minute arc passage. 2. The process according to claim 1, wherein the syngas is cooled to separate and recover water as second condensed water, and steam is generated from the second condensed water and supplied as the plasma gas into the minute arc passage. And producing the alternative natural gas. 3. The method according to claim 1, further comprising a step of refluxing a part of the synthesis gas as an assist gas into the thermal plasma reaction chamber. 4. The thermal plasma reactor according to claim 1, wherein the arc electrode is disposed at one end of the thermal plasma reaction chamber and at the other end of the thermal plasma reaction chamber. A neutral electrode, further comprising: simultaneously generating a plurality of thermal plasma columns in the minute arc passage between the multi-phase AC electrode and the neutral electrode; A method for producing an alternative natural gas, comprising a step of causing a contact reaction between the plasma gas and the solid carbon material while rotating periodically in the shaped carbon material. 5. A step of preparing a plasma reactor having a thermal plasma reaction chamber and an arc electrode disposed in the thermal plasma reaction chamber; and filling the thermal plasma reaction chamber with a solid carbon material to form a solid carbon material. Forming a minute arc passage in a gap between the electrodes; supplying arc power to an arc electrode to generate thermal plasma in the minute arc passage; and causing thermal plasma while passing a plasma gas comprising water vapor into the minute arc passage. Generating a H ₂ , CO-containing synthesis gas by contacting the plasma gas with the carbon of the solid carbon material to generate a synthesis gas; detecting the concentration of H ₂ , CO in the synthesis gas to generate a detection signal. Outputting; H from the detection signal
Calculating the ₂ / CO ratio and outputting an arc current control signal; and controlling the thermal plasma temperature by varying the arc current in response to the arc current control signal, thereby obtaining H ₂ / CO.
Adjusting the ratio to a predetermined value or more; contacting the synthesis gas of the predetermined value with the methanation catalyst in the methanation reaction tank to synthesize a water-containing methane-rich gas; cooling the methane-rich gas to remove the methane-rich gas from the methane-rich gas; (1) A method for producing a natural gas alternative, comprising: separating and recovering condensed water; and converting the first condensed water into steam and supplying it as the plasma gas into the minute arc passage. 6. The process according to claim 5, wherein the syngas is cooled to separate and recover water as second condensed water, and steam is generated from the second condensed water and supplied as the plasma gas into the micro arc passage. And producing the alternative natural gas. 7. The method for producing a natural gas alternative according to claim 5, further comprising a step of refluxing a part of the synthesis gas into the thermal plasma reaction chamber as an assist gas. 8. The thermal plasma reactor according to claim 5, wherein the arc electrode is disposed at one end of the thermal plasma reaction chamber and at the other end of the thermal plasma reaction chamber. A neutral electrode, further comprising: simultaneously generating a plurality of thermal plasma columns in the minute arc passage between the multi-phase AC electrode and the neutral electrode; A method for producing an alternative natural gas, comprising a step of causing a contact reaction between the plasma gas and the solid carbon material while rotating periodically in the shaped carbon material. 9. A thermal plasma reactor having a closed thermal plasma reaction chamber, and an arc electrode disposed in the thermal plasma reaction chamber; a carbon material supply device for supplying a solid carbon material to the thermal plasma reaction chamber; A raw water supply line for supplying raw water to the thermal plasma reaction chamber; a plurality of fine arc passages formed in the gap between the solid carbon materials formed in the thermal plasma reaction chamber; A synthesis gas generation unit that generates a thermal plasma in an arc passage to generate a synthesis gas containing H ₂ and CO by a contact reaction between the plasma gas and the solid carbon material; and a plasma that supplies an arc current to the arc electrode. A power source; controlling the arc current to vary the thermal plasma temperature,
A control device for adjusting the ₂ / CO ratio to a predetermined value or more; a methanation reactor for synthesizing a water-containing methane-rich gas from the synthesis gas; and a heat exchanger for cooling the methane-rich gas and separating and recovering condensed water from the methane-rich gas. A condensed water reflux line for returning condensed water to the thermal plasma reaction chamber;
An alternative natural gas production device comprising: 10. The alternative natural gas production apparatus according to claim 9, wherein the thermal plasma reaction chamber includes a steam generation unit formed upstream of the synthesis gas generation unit to convert raw water into a plasma gas composed of steam. 11. The thermal plasma reaction chamber according to claim 9, wherein the arc electrode comprises a multi-phase AC electrode disposed at one end of the thermal plasma reaction chamber and a neutral electrode disposed at the other end of the thermal plasma reaction chamber. Comprising, further, the plasma power source simultaneously generates a plurality of thermal plasma columns in the micro arc passage between the multi-phase AC electrode and the neutral electrode,
An alternative natural gas production apparatus comprising a multi-phase AC power supply for causing a reaction between the plasma gas and the solid carbon material while periodically rotating the plurality of thermal plasma columns in the solid carbon material.