JP2002179403A - Natural gas reforming system and natural gas reforming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a natural gas reforming system and a natural gas reforming device, in which a device for separating and recovering only CO2 is not required. SOLUTION: The natural gas reforming system is provided with at least 3 reforming apparatuses, in which an H2 production mode for reacting methane gas G1 with a catalyst S to deposit carbon on the surface of the catalyst and to produce hydrogen G8, a CO2 adsorption mode for adsorbing/absorbing carbon dioxide in the waste combustion gas G4 successive to the H2 production mode and a CO production mode for producing carbon monoxide G9 by reacting the carbon deposited in the H2 production mode with carbon dioxide adsorbed/absorbed in the CO2 adsorption mode are performed stepwise and the H2 production mode is performed in the 1st reforming apparatus 2a, the CO2 adsorption mode is performed in the 2nd reforming apparatus 2b and the CO production mode is performed in the 3rd reforming apparatus 2c. Hydrogen G8 produced in the H2 production mode and carbon monoxide G9 produced in the CO production mode are supplied to a combustor 3 such as an engine and the waste combustion gas G4 is supplied to the reforming apparatus 2b in the CO2 adsorption mode and the execution mode in each reforming apparatus 2a, 2b and 2c is switched successively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a natural gas reforming system and a natural gas reforming apparatus, and more particularly to a natural gas containing methane gas (CH ₄ ) as a main component and carbon dioxide (CO 2).
₂ ) The present invention relates to a natural gas reforming system and a natural gas reforming apparatus using hydrogen (H ₂ ) and carbon monoxide (CO) as a fuel by reacting them to form a fuel.

[0002]

2. Description of the Related Art Natural gas containing methane gas (CH ₄ ) as a main component has the advantage that it does not emit as much air pollutants as petroleum fuel during combustion, but has a low calorific value and low fuel consumption. Is not very good.

Therefore, in recent years, natural gas and carbon dioxide (C
O_Two ) To react with hydrogen (H_Two ) And carbon monoxide (CO)
To H_Two And CO gas engines and gas turbines
Natural gas reforming system used as fuel for combustors such as
The device is employed. This natural gas reforming system and equipment
By default, H_Two And CO as fuel, CH _Four 
Fuel consumption is increased and fuel consumption is higher than when using
Is improved.

A conventional natural gas reformer is shown in FIG.
Yeah, CH_Four CH that supplies (G1) _Four Gas tank 41
And CH_Four (G1) reformer 42 for reforming, after reforming
And a combustor 43 for burning the gas component G3 of the exhaust gas G4.
CO_Two CO that separates and collects _Two Separation device 44 and reforming
CO from later gas content G3_Two Adsorbs and absorbs CO_Two adsorption
It is mainly composed of devices 45a, 45b, 45c. here
The reformer 42 and each CO_Two Suction devices 45a, 45
b, 45c are provided with heat exchange means 46.

[0005] First, CH ₄ (G1) supplied from the CH ₄ gas tank 41, CO ₂ high temperature supplied from the separator 44 (hundreds ° C.) of the separation gas (N _2, CO ₂₎ is mixed with G5, The mixed gas (CH ₄ , N ₂ , CO ₂ ) G 2 is supplied to the CO ₂ through the line 51 and the lines 51 a, 51 b, 51 c.
It is supplied to the inlet side (right side in FIG. 4) of the adsorption devices 45a, 45b, 45c, and heat-exchanges with a part of the combustion exhaust gas G4 to heat it to a high temperature. Thereafter, the mixed gas G2 is supplied to the line 52.
a, 52b, 52c, the CO ₂ adsorbers 45b, 4
It is supplied to the outlet side of 5c and 45a (the left side in FIG. 4) and heat is again exchanged to heat it to a high temperature.

Next, the high-temperature mixed gas G2 is supplied to a line 5
3b, 53c, and supplied to the reformer 42 via 53a and the line 53, together with further and a part of the combustion exhaust gas G4 heat exchanger is heated to a high temperature, the reforming and generation was CH ₄ to C and H ₂ The C is reacted with CO ₂ in the mixed gas G2 to generate CO.

Next, the gas content after reforming (H ₂ , CO, N
₂ , CO ₂ , CH ₄ (unmodified) etc.)
The gas is supplied to the inlet side of the CO ₂ adsorbers 45a, 45b, 45c via the lines 56a, 56b, 56c, and exchanges heat with the above-mentioned mixed gas G2 to a low temperature of about 200 ° C. Thereafter, the gas G3 is transferred to the lines 57a, 57b, 57c.
And is supplied to the combustor 43 via the line 57, and is burned together with the air G7. The flue gas (N ₂ , CO ₂ , O ₂ (excess)) G 4 is supplied to the CO ₂ separation device 44 via the heat exchange means 46, and a part of the G 5 is recovered and the CH ₄ from the CH ₄ gas tank 41 is recovered. ₄ and the remainder G6 is released into the atmosphere.

[0008]

By the way, in the conventional natural gas reforming system / apparatus, in addition to the reformer 42 for reforming CH ₄ (G1), the CO ₂ gas is discharged from the combustion exhaust gas G4.
Since the CO ₂ separation device 44 for separating and recovering the components is required, there is a problem that the system and the device become large.

Here, the CO shown in FIG._Two Separation device 44
Instead of distributing the flue gas G4 (eg,
Gas reforming system with a header (not shown)
There are also devices. CO_Two When the separation device 44 is used, CO 2
_Two The separation device 44 removes the CO in the flue gas G4._Two Minute efficiency
Can be separated and recovered (recovery rate: about 70%). _Four 
The flow rate of the recovered gas G5 used for mixing with (G1) is CH_Four 
It is relatively small, about 4 to 5 times the flow rate of (G1). this
If this header is used, the header
Since only gas G4 is distributed, CH_Four (G1) reforming
CO required for _Two To ensure the flow rate of the recovered gas G5
But CH_Four (G1) is about 10 times more than the flow rate
However, there is a problem that the heat exchange efficiency is reduced.

Further, since excess air G7 is supplied to the combustor 43, excess oxygen (O ₂ ) is present in the flue gas G4. Over a predetermined concentration (eg, about 0-3%)
_{When 2} remains, O ₂ having a predetermined concentration or more may be mixed into the mixed gas G 2 even if the CO ₂ separation device 44 is used. In this case, there is a possibility that H ₂ generated in the reformer 42 and the mixed O ₂ may react violently to cause damage inside the reformer 42, which may lead to a reduction in the life of the device.

Further, in the conventional natural gas reforming system / apparatus, H ₂ and CO are generated in the same reforming apparatus 42 and in the same process. However, CH ₄
→ C + 2H ₂ reaction temperature conditions and C + CO ₂ →
The temperature conditions under which reaction occurs the 2CO differ, the same reformer within 42, and, at the same step, a conventional natural gas reforming system for the production of H ₂ and CO are both reactions each other reaction Methane reforming rate was not so good.

An object of the present invention, which has been made in view of the above circumstances, is to provide a natural gas reforming system and a natural gas reforming apparatus that do not require a dedicated device for separating and recovering CO _2. It is in.

[0013]

In order to achieve the above object, a natural gas reforming system according to the present invention comprises a methane gas (CH)
₄ ) In a natural gas reforming system in which natural gas mainly composed of) is reacted with carbon dioxide (CO ₂ ) to reform it into hydrogen (H ₂ ) and carbon monoxide (CO), and this is used as a fuel, and H ₂ generation mode for generating of H ₂ with precipitating a carbon (C) on the catalyst surface and the CH ₄ is reacted with the catalyst, CO ₂ for adsorbing or absorbing CO ₂ in the combustion exhaust gas is followed in H ₂ generation mode C deposited in the H ₂ generation mode and CO absorbed and absorbed in the CO ₂ adsorption mode
₂ comprising at least three reformers capable of sequentially executing a CO generation mode for generating CO by reacting ₂ ; a first reformer being a H ₂ generation mode; a second reformer being a CO ₂ adsorption mode; and executes the third reformer as CO generating mode, the CO produced by the H ₂ and CO generation mode generated with H ₂ generation mode, and supplied to the combustor such as an engine, resulting in the combustor combustion The exhaust gas is supplied to the reformer in the CO ₂ adsorption mode to be exhausted, and the execution mode of each of these reformers is sequentially switched.

According to the above, by sequentially switching the execution mode of each reformer, H ₂ generation and C
O generation and CO ₂ adsorption can be performed.
_No special equipment for separating and collecting ₂ is required.

When the combustion exhaust gas from the combustor is supplied to the reformer in the CO ₂ adsorption mode, the combustion exhaust gas is supplied to the reformer in the H ₂ generation mode and the CO generation mode. May be supplied to the heat transfer section and heated, and then supplied to the reformer in which the CO ₂ adsorption mode is executed.

Further, in the combustion exhaust gas, a predetermined concentration or more of oxygen (O ₂₎ may remain due to incomplete combustion, the O ₂
Is adsorbed in the CO ₂ adsorption mode and remains in the reformer in the subsequent CO generation mode. At the start of the H ₂ generation mode, the supplied CH ₄ is gradually burned using the ignition means. The remaining O ₂ may be removed.

On the other hand, the natural gas reformer according to the present invention
Methane gas (CH_Four ) -Based natural gas and dioxide
Carbon (CO_Two ) To react with hydrogen (H_Two ) And carbon monoxide
(CO) reformed and used as fuel
In the quality device, the CH_FourWith the catalyst
Deposit carbon (C) on the surface and_Two H that produces _Two 
Generation mode and H_Two Following the production mode,
CO_Two Adsorbs and absorbs CO_Two Suction mode and H_Two Generate
And CO deposited in mode_Two Adsorbed / absorbed in adsorption mode
CO_Two Generation mode in which CO is reacted to produce CO
And at least three reformers capable of sequentially performing
One reformer is H_Two Production mode, the second reformer is CO
_Two Adsorption mode, third reformer as CO generation mode
Execute and H_Two H generated in generation mode_Two And CO
The CO generated in the generation mode is supplied to a combustor such as an engine.
And the combustion exhaust gas generated by the combustor is_Two Adsorption mode
Supply to the reforming unit for the exhaust gas,
The execution modes of the devices are sequentially switched.
In addition, the above natural gas is supplied to the gas inlet side of each of the above reformers.
CH to supply_Four Combustion exhaust gas that supplies lines and combustion exhaust gas
Sline and H on the gas outlet side_Two Generation mode or C
H generated in O generation mode_Two Or an emission line that emits CO
Inn and CO_Two Nitrogen separated in adsorption mode (N_Two )
N to issue_Two Connect the lines independently
Valves and valves to control the flow of each gas in each line
Is connected to control means for controlling the opening and closing of.

According to the above configuration, since the flow of gas supplied to each reformer can be controlled by the control means and the valve, different modes (H ₂ generation mode, CO ₂ (Adsorption mode, CO generation mode) can be executed, and by sequentially switching the execution mode of each reformer, one reformer can perform three processes of H ₂ generation, CO generation, and CO ₂ adsorption. It can be performed.

Further, an O ₂ sensor for measuring the oxygen concentration in the combustion exhaust gas in the combustion exhaust gas line provided, each ignition means to the connection port near the CH ₄ lines of each reformer provided, the O ₂ sensor and the The ignition means may be connected to the control means.

The catalyst is preferably a simple substance selected from Group VIII metals, Group IB metals, rare earth oxides, alkali metal oxides and alkaline earth metal oxides, or a mixture thereof.

Further, CO ₂ in the combustion exhaust gas is adsorbed and
For absorption, it is preferable to arrange an adsorbent / absorbent selected from activated carbon, zeolite, alkaline earth metal oxide, or rare earth oxide in each reformer.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 3 show schematic views of a natural gas reforming apparatus according to the present invention.

As shown in FIGS. 1 to 3, a natural gas reforming device according to the present invention, a CH ₄ gas tank 1 for supplying natural gas mainly composed of methane (CH ₄₎ G1, CH ₄
(G1) reacts with the methane reforming catalyst S to precipitate carbon (C) on the surface of the catalyst S and generate H ₂ (G8).
And ₂ generating mode, the combustion exhaust gas G4 is followed in H ₂ generation mode
And CO ₂ adsorption mode for adsorbing or absorbing CO ₂ in, H ₂
CO which is reacted with CO ₂ adsorbed and absorbed by precipitated in generation mode C and CO ₂ adsorption mode to generate a CO (G9)
At least three reformers capable of sequentially executing the generation mode (three reformers 2a to 2c are shown in FIGS. 1 to 3)
2 and a combustor 3 for burning a combustion gas (reformed gas portion) G10.

[0025] The gas inlet side of each reformer 2 (right side in FIGS. 1 to 3), CH ₄ (G1) flue gas line 15 for supplying a CH ₄ line 11 and the combustion exhaust gas G4 supplies
There, the gas outlet side (in FIGS. 1 to 3 left), the (discharging or CO generated by the generation mode CO (G9)) for discharging of H ₂ generated with H ₂ generation mode (G8) emissions The line 12 and the N ₂ line 16 for discharging the nitrogen (N ₂ ) G 6 separated in the CO ₂ adsorption mode are connected independently. Further, each reformer 2 includes a heat exchange means 6,
A line 13 on the introduction side (left side in FIGS. 1 to 3) of the heat exchange means 6 is on the discharge side (right side in FIGS. 1 to 3) of the combustor 3.
A discharge side (right side in FIGS. 1 to 3) line 14 of the heat exchange means 6 is connected to a flue gas line 15. Electromagnetic valves VA1 to VA6, VB1 to VB6, VC1 for controlling the flow of each gas G1, G8, G9, G4, G6 are provided in these lines 11 to 16, respectively.
~ VC6.

The flue gas line 15 (or line 13)
Is provided with an O ₂ sensor 24 for measuring the O ₂ concentration in the combustion exhaust gas G4. An ignition plug (ignition means) 21 is provided in the vicinity of the connection port of the CH ₄ line 11 of each reformer 2.

Each of the solenoid valves VA1 to VA6, VB1 to VB6, VC
1 ~VC6, O ₂ sensor 24, and the ignition plug 21, respectively, are connected to the control means 22 connected to the power source 23, the electromagnetic valves VA1 ~VA6, VB1 ~VB6, VC1 ~
The VC6 (or the spark plug 21) is individually controlled to open and close (or to be ON / OFF controlled).

The heat exchanging means 6 forms a carrier layer on the surface of the heat radiating pipe 6d, carries the methane reforming catalyst S on the surface of the carrier layer, and holds the CO ₂ adsorbing / absorbing agent K. The heat radiating pipe 6d is arranged in a meandering manner in the casing 2d of the reformer 2. Or
The heat-dissipating pipe 6d having a carrier layer on the surface is transformed into a reformer 2
The methane reforming catalyst S and CO ₂ are disposed between the meandering heat radiation pipes 6d while being arranged in a meandering manner in the casing 2d.
The adsorption / absorption agent K is carried and held. Here, as the heat-dissipating pipe 6d, any pipe used for a conventional heat exchanger or the like can be applied. Alternatively, the heat radiation pipe 6d having fins on the outer peripheral surface may be used.

As the methane reforming catalyst S, C at a high temperature
There is no particular limitation as long as CH ₄ can be reformed into C and H ₂ by contact with H ₄ (G1).
A simple substance selected from a Group II metal, a Group IB metal, a rare earth oxide, an alkali metal oxide, an alkaline earth metal oxide, or a mixture thereof is exemplified.

As the CO ₂ adsorbent / absorbent K, a relatively low temperature at which sensible heat is recovered by heat exchange (for example,
It is not particularly limited as long as it can adsorb and absorb CO ₂ in the combustion exhaust gas G4 of about 200 to 300 ° C.)
Activated carbon, zeolite, alkaline earth metal oxides (eg, MgO, CaO, etc.), or rare earth oxides (eg,
CeO _{2 and the} like, and those having high adsorption / absorption ability at a temperature close to room temperature are more preferable.

Next, the operation of the natural gas reforming system and the natural gas reforming apparatus according to the present invention will be described.

First, prior to the start of reforming, as shown in FIG. 1, the control means 22 controls the solenoid valves VA1, VA4, VC1.
, VC4 are opened and the flue gas G4 is supplied to the heat exchange means 6 of the reformers 2a, 2c via the lines 13a, 13c, respectively.
And the methane reforming catalyst S in the reformer 2a, the methane reforming catalyst S in the reformer 2c and the CO ₂ adsorbent / absorbent K
Is heated and activated in advance.

Next, as shown in FIG. 1, the electromagnetic valves VA3 and VA5 of the reformer 2a are opened by the control means 22, and C
CH ₄ (G1) supplied from the H ₄ gas tank 1 is led in the order of line 11 → line 11a and supplied into the reformer 2a in the H ₂ generation mode. In the reformer 2a, the high-temperature (for example, about 600 to 750 ° C.) combustion exhaust gas G4 generated by the heat exchange means 6 heats the methane reforming catalyst S to a high temperature with its sensible heat. This high-temperature methane reforming catalyst S and CH ₄ (G
When 1) contacts in a high-temperature atmosphere (for example, around 600 ° C.), solid C precipitates on the surface of the methane reforming catalyst S, and gaseous H ₂ (G8) is generated. H ₂ (G8) generated by the reforming is discharged from the reformer 2a via the discharge line 12a.

At the same time as the H ₂ generation mode of the reformer 2a, as shown in FIG.
c, the electromagnetic valve VC5 is opened, and in the reformer 2c in the CO generation mode, the high temperature (for example, about 6
With the sensible heat of the combustion exhaust gas G4 (at 00 to 750 ° C.), the methane reforming catalyst S and the CO ₂ adsorbent / absorbent K are heated to a high temperature (for example, about 600 to 700 ° C.). By heating the methane reforming catalyst S and the CO ₂ adsorbent / absorbent K to a high temperature, the CO adsorbed and absorbed by the CO ₂ adsorbent / absorbent K by C deposited on the surface of the methane reforming catalyst S ₂ is reduced to produce CO (G9). This CO (G9) is discharged from the inside of the reformer 2c via the discharge line 12c. Here, C of the surface of the methane reforming catalyst S in the reformer 2c
Are those deposited in H ₂ generation mode of the second previous step, also, CO ₂ in CO ₂ adsorption and absorption agent K is obtained by adsorption and absorbed before CO ₂ adsorption mode process.

At the same time, as shown in FIG. 1, the electromagnetic valves VB2 and VB6 of the reformer 2b are opened by the control means 22 and a relatively low temperature (for example, about 200-300 ° C) flue gas G4,
Lines 14a and 14c → line 14 → combustion exhaust gas line 15 → combustion exhaust gas line 15b are supplied to the reformer 2b in the CO ₂ adsorption mode. In the reformer 2b, the CO ₂ content in the flue gas G4 becomes CO ₂ adsorbent / absorbent K
And / or adsorbed and absorbed by C deposited on the surface of the methane reforming catalyst S, and the remaining N ₂ (including a small amount of CO ₂ ; G
6), through the N ₂ line 16b is discharged from the reforming device 2b, it is released into the atmosphere (discharge temperature: for example, about 100 to 200 ° C.). Part of this N ₂ (G6)
The temperature may be returned to 3a, 13c and used for adjusting the temperature of the combustion exhaust gas G4. Here, C on the surface of the methane reforming catalyst S in the reformer 2b is deposited during the H ₂ generation mode in the previous step.

H ₂ (G8) and CO (G9) simultaneously produced in the reformers 2a and 2c are mixed in the discharge line 12, and are burned together with air G7 as a combustion gas G10 (for example, a gas engine, a gas turbine, etc.). 3) supplied to
Used as fuel. At this time, H ₂ (G8) generated in the reformer 2a is concentrated using a hydrogen gas filter and / or an H gas absorbent, and the concentrated H ₂ is CO (G
9) and may be supplied to the combustor 3.

Here, as a result of actually measuring the methane reforming rate and the energy efficiency of the present system using a gas turbine as the combustor 3, a methane reforming rate of 80% and an energy efficiency of 50% were obtained. .

Thereafter, when the operation of the natural gas reformer is continued in the state shown in FIG. 1, the amount of C deposited on the surface of the methane reforming catalyst S gradually increases in the reformer 2a. By doing so, the reforming rate gradually decreases, and the amount of H ₂ (G8) generated decreases. In the reformer 2b,
CO ₂ adsorption and absorption agent K that CO ₂ is gradually adsorbed and absorbed, adsorbed, absorbed amount of CO ₂ decreases gradually. Further, in the reformer 2c, by CO formation reaction proceeds, CO ₂ adsorption and absorption of precipitated C amount and CO ₂ adsorbent, absorbent K of the surface of the methane reforming catalyst S gradually reduced , CO (G9) is reduced. If the operation is continued thereafter, each reformer 2 eventually loses its function.

Therefore, in the state shown in FIG. 1, if the operation of the natural gas reforming unit is continued for a certain period of time (for example, two to three minutes), as shown in FIG.
Close VA1, VA3, VA4, VA5, VB2, VB6 and
New solenoid valves VA2, VA6, VB1, VB4, VB5, VC3
Open. That is, the reformer 2a is in the CO ₂ adsorption mode, the reformer 2b is in the CO generation mode, and the reformer 2c is in the H mode.
It becomes ₂ generation mode.

As a result, H ₂ (G8) is supplied to the reformer 2c.
The CO (G9) is generated in the reformer 2b and discharged from the reformer 2c (or 2b) via the discharge line 12c (or 12b), and is mixed in the discharge line 12 to produce the combustion gas. Combustor 3 with air G7 as G10
Supplied to Moreover, CO ₂ in the combustion exhaust gas G4 are adsorbed and absorbed by the reformer 2a, N ₂ (G6) is, N ₂ line 1
It is discharged from the reformer 2a via 6a and discharged to the atmosphere.

Thereafter, when the operation of the natural gas reformer is continued for a certain period of time in the state shown in FIG. 2, as shown in FIG. 3, the control means 22 controls the electromagnetic valves VA2, VA6, VC1, VC3, VC3.
VC4 and VC5 are closed and solenoid valves VA1 and VA4 are newly added.
, VA5, VB3, VC2, VC6 are opened. That is, the reformer 2a is in the CO generation mode, the reformer 2b is in the H ₂ generation mode, and the reformer 2c is in the CO ₂ adsorption mode.

As a result, H ₂ (G8) is supplied to the reformer 2b.
The CO (G9) is generated in the reformer 2a and discharged from the reformer 2b (or 2a) via the discharge line 12b (or 12a), mixed in the discharge line 12, and combusted by the combustion gas. Combustor 3 with air G7 as G10
Supplied to Moreover, CO ₂ in the combustion exhaust gas G4 are adsorbed and absorbed by the reformer 2c, N ₂ (G6) is, N ₂ line 1
It is discharged from the reformer 2c via 6c and discharged to the atmosphere.

As described above, the natural gas according to the present invention is
According to the reforming system, the execution of the reformer 2a at a certain time
Set the mode to H_Two The generation mode and the execution mode of the reformer 2b
CO _Two The CO mode is used for the adsorption mode and the execution mode of the reformer 2c.
Mode (see Fig. 1), and then
The execution mode of the quality device 2a is H_Two Generation mode → CO_Two adsorption
Mode → CO generation mode → H_Two Generate mode ...
Mode of the quality device 2b is set to CO_Two Adsorption mode → CO generation
Mode → H_Two Generation mode → CO_Two Adsorption mode ...
Change the execution mode of the reformer 2c from the CO generation mode to H_Two Generate
Mode → CO_TwoAdsorption mode → CO generation mode ...
By switching each, H_Two Generation mode and CO production
In the reformer in the natural mode (2a and 2c in FIG. 1)
And H_Two (G8) and CO (G9) can be generated simultaneously.
Wear.

The reformer (2b in FIG. 1) can adsorb and absorb the CO ₂ in the flue gas G4, as in the conventional natural gas reforming system shown in FIG. Since a dedicated device such as the CO ₂ separation device 44 is not required, the system and the device are compact. This C
The adsorption / absorption rate of CO ₂ using the reformer in the O ₂ adsorption mode is comparable to the case of adsorbing / absorbing CO ₂ using the conventional CO ₂ separator 44, and There is no decrease in heat exchange efficiency as in the case of using the header described above.

Further, according to the present invention, H_Two (G8) Raw
H is H_Two In the reformer in the production mode (2a in FIG. 1),
CO (G9) is produced in the reformer in the CO production mode (Fig. 1
In 2c), H in separate reformers 2_Two 
(G8) and CO (G9). In addition, each reform
As described above, the temperature in the device 2 is determined by the combustion exhaust gas G4 and
N_Two It can be adjusted freely by (G6). Therefore, each
The temperature of the reformer 2 is set to H _Two (G8) or CO (G9) generation
By adjusting each to the optimal temperature conditions for
The quality can be further improved.

On the other hand, in the natural gas reforming system according to the present invention, when the reforming of the natural gas is performed while sequentially switching the execution mode of each reformer 2, at a certain point during the gas reforming, When the incomplete combustion or the like occurs in the vessel 3, a predetermined concentration (for example, about 0 to 3%) is contained in the flue gas G4.
The above oxygen (O ₂ ) remains. If O ₂ having a predetermined concentration or more is adsorbed and remains in the reformer in the CO ₂ adsorption mode, and is adsorbed and remains in the reformer even after passing through the CO generation mode, the reformer is when it becomes with H ₂ generation mode, O ₂ adsorbed, it remains with H ₂ generated in the reformer is likely to react violently.

Therefore, the O provided in the flue gas line 15
The _second sensor 24 measures the O ₂ concentration in the combustion exhaust gas G4 at all times, when the O ₂ concentration equal to or higher than the predetermined concentration in the combustion exhaust gas G4 is determined, enter the O ₂ concentration signal to the control means 22, control means 22 Specifies the reformer (2b in FIG. 1) in the CO ₂ adsorption mode (FIG. 1) at this time.

Thereafter, it is assumed that O ₂ having a concentration equal to or higher than the predetermined concentration is adsorbed and remains in the reformer 2b, and is adsorbed and remains in the reformer 2b even after the subsequent CO generation mode (FIG. 2). Also, the reformer 2b operates in the H ₂ generation mode (see FIG. 3).
Is reached, the control means 22 ignites the spark plug 21b and gradually burns CH ₄ (G1) supplied into the reformer 2b.

As a result, the O ₂ adsorbed and remaining in the reformer 2b can be burned and removed (or the concentration of the adsorbed and remaining O ₂ can be made lower than a predetermined concentration).
Also, in the reforming apparatus within 2, there is no possibility H ₂ where (G8) and O ₂ which has been adsorbed and remaining through CO ₂ adsorption mode and CO generation mode for generating with H ₂ generation mode react violently, and hence Can extend the life of the device.

Next, another embodiment of the present invention will be described.

In the natural gas reforming system according to the present invention, H ₂ (G
8) and CO (G9) were supplied to the combustor 3 in a mixed state. On the other hand, in the natural gas reforming system according to the present embodiment, H ₂ (G8) and CO
(G9) is not mixed, and only CO (G9) is supplied to the combustor 3 and H ₂ (G8) is supplied to a fuel cell (not shown). At this time, the generated H ₂ (G8) may be concentrated using a hydrogen gas filter and / or an H gas absorbent, and the concentrated H ₂ may be supplied to the fuel cell.

[0052] Natural gas reforming system according to the present embodiment
According to the above, in the combustor 3, H _Two (G8) almost flows
Without CO, only CO (G9) is used as fuel
As a result, combustion can be controlled with high accuracy,
The fuel of the vehicle engine (gas engine)
And it can be used effectively.

Since H ₂ (G8) is effectively used as fuel for power generation in the fuel cell, a large amount of power can be obtained in the fuel cell at the same time as power is obtained in the combustor 3.

Furthermore, as a result of actually measuring the methane reforming rate and the energy efficiency of the system according to the present embodiment using a gas turbine as the combustor 3, the methane reforming rate of 80% and the energy efficiency of 52% Was obtained, and higher energy efficiency was obtained than the system according to the present invention.

As described above, the embodiments of the present invention are not limited to the above-described embodiments, and it is needless to say that various other embodiments are also conceivable.

[0056]

In summary, according to the present invention, at least three reformers capable of sequentially executing the H ₂ generation mode, the CO ₂ adsorption mode, and the CO generation mode are provided. ₂ reforming mode, the second reforming unit is executed in the CO ₂ adsorption mode, and the third reforming unit is executed in the CO generating mode, and the execution mode of each of these reforming units is sequentially switched to one reforming unit. in, H ₂ generation, CO generation, and CO ₂ can make three adsorption, and separation of CO ₂
An excellent effect of eliminating the need for a dedicated device for collection is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the flow of each gas at a certain point in a natural gas reforming system according to the present invention.

FIG. 2 is a schematic diagram showing a flow of each gas at a point in time when a certain time has elapsed from the point in FIG.

FIG. 3 is a schematic diagram showing the flow of each gas at a point in time when a certain time has elapsed from the point in FIG. 2;

FIG. 4 is a schematic diagram showing a flow of each gas in a conventional natural gas reforming system.

[Explanation of symbols]

2 Reformer 2a Reformer (first reformer) 2b Reformer (second reformer) 2c Reformer (third reformer) 3 Combustor 6 Heat exchange means (heat transfer) part) 11 CH ₄ line 12 exhaust line 15 flue gas line 16 N ₂ line 21 ignition plug (ignition means) 22 control means 24 O ₂ sensor G1 CH ₄ (methane) G4 flue gas G8 H ₂ (hydrogen) G9 CO (one carbon oxide) VA1 ~VA6, VB1 ~VB6, VC1 ~VC6 solenoid valve (valve) K CO ₂ adsorption and absorption agent (adsorbent-absorber) S methane reforming catalyst (catalyst)

Continued on the front page F term (reference) 3K068 AA01 AB19 AB36 4G040 EA03 EA05 EB01 EB03 EB18 EB41 EB42 EB43 EC02 EC03 EC04 EC05 4G140 EA03 EA05 EB01 EB03 EB18 EB41 EB42 EB43 EC02 EC03 EC04 EC05

Claims (8)

[Claims] 1. Methane gas (CH)_Four )
Natural gas and carbon dioxide (CO_Two ) To react with hydrogen (H
_Two ) And carbon monoxide (CO), which are used as fuel
In the natural gas reforming system used, the CH_Four Touch
When carbon (C) is precipitated on the catalyst surface by reacting with
To H_Two H that produces_Two Generation mode and H _Two In generation mode
Next, CO in the combustion exhaust gas_Two Adsorbs and absorbs CO_Two Sucking
Wearing mode and H_Two C and CO deposited in generation mode_Two adsorption
CO absorbed and absorbed in mode_TwoReact to produce CO
At least three modes that can sequentially execute the generated CO generation modes
And the first reformer is H_Two Generation mode,
The second reformer is CO_Two Adsorption mode, third reformer
Execute as CO generation mode and H_Two Generation mode
H generated by_Two And CO generated in CO generation mode
Engine, etc., and the combustion
CO gas_Two Supply to the reformer in adsorption mode and exhaust,
In addition, the execution mode of each of these reformers must be sequentially switched.
And a natural gas reforming system. 2. When a combustion exhaust gas from a combustor is supplied to a reformer in which a CO ₂ adsorption mode is executed, the combustion exhaust gas is subjected to an H ₂ generation mode and a CO generation mode. After supplying these to the heat transfer section and heating them,
The natural gas reforming system according to claim 1, wherein the natural gas reforming system is supplied to a reformer in which the CO ₂ adsorption mode is performed. To 3. A combustion exhaust gas, a predetermined concentration or more of oxygen (O ₂₎ may remain due to incomplete combustion, its O _2, C
When adsorbed in the O ₂ adsorption mode and remains in the reformer in the subsequent CO generation mode, at the start of the H ₂ generation mode, the supplied CH ₄ is gradually burned using the ignition means, and the remaining O 2 is burned. _2. The natural gas reforming system according to claim 1, wherein ₂ is removed. 4. A reaction between natural gas containing methane gas (CH ₄ ) as a main component and carbon dioxide (CO ₂ ) to produce hydrogen (H ₂ ).
₂ ) and carbon monoxide (CO), and in a natural gas reformer using the same as fuel, the above-mentioned CH ₄ is reacted with a catalyst to deposit carbon (C) on the catalyst surface and H
And H ₂ generation mode for generating the _2, H ₂ and CO ₂ adsorption mode followed by adsorption and absorption of CO ₂ in the combustion exhaust gas in the generation mode, adsorption and the C and CO ₂ adsorption mode precipitated with H ₂ generation mode At least three reformers capable of sequentially performing a CO generation mode for reacting the absorbed CO ₂ to generate CO are provided. The first reformer is an H ₂ generation mode, and the second reformer is a CO generator. ₂ adsorption mode, the third reformer is CO
And executes a generating mode, the CO produced in the generated H ₂ and CO generated mode with H ₂ generation mode, and supplied to the combustor such as an engine, a combustion exhaust gas produced in the combustor of the CO ₂ adsorption mode breaks A natural gas reformer characterized in that the gas is supplied to a reformer and exhausted, and the execution mode of each of these reformers is sequentially switched. 5. The apparatus according to claim 5, wherein the gas inlet side of each of the reformers has the ceiling.
CH that supplies natural gas_Four Supply line and flue gas
A flue gas line and H on the gas outlet side _Two Generation mode
Generated in the CO or CO generation mode_Two Or emit CO
Discharge line and CO_Two Nitrogen separated in adsorption mode (N
_Two N) to discharge_Two Connect each line independently
Each of these lines has a valve that controls the flow of each gas.
Control means for controlling the opening and closing of the valve and the valve.
4. The natural gas reformer according to 4. 6. provided an O ₂ sensor for measuring the oxygen concentration in the combustion exhaust gas in the combustion exhaust gas line, respectively ignition means to the connection port near the CH ₄ lines of each reformer provided, the O ₂ sensor and the 6. The natural gas reformer according to claim 4, wherein an ignition means is connected to the control means. 7. The catalyst according to claim 1, wherein the catalyst is a Group VIII metal, a Group IB metal,
The natural gas reformer according to any one of claims 4 to 6, wherein the natural gas reformer is a simple substance selected from a rare earth oxide, an alkali metal oxide, and an alkaline earth metal oxide, or a mixture thereof. 8. An adsorbent / absorbent selected from activated carbon, zeolite, alkaline earth metal oxide or rare earth oxide is disposed in each reformer in order to adsorb and absorb CO ₂ in the combustion exhaust gas. The natural gas reformer according to any one of claims 4 to 6.