JP2002114986A - Method and apparatus for producing gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a gas containing at least one kind to be selected from the group consisting of hydrogen, methane, and carbon monoxide under mild conditions not to cause the corrosion of the material of a reaction vessel or the deterioration of a catalyst which can inhibit the generation of harmful nitrogen oxides, and an apparatus for producing a gas which is suited in carrying out the production method. SOLUTION: The method for producing a gas containing at least one selected from the group consisting of hydrogen, methane and carbon monoxide has a step of gasifying at least part of a fossil fuel in the presence of steam in the supercritical state or in the subcritical state of carbon dioxide. The apparatus for producing the gas enables the gasification of part of a fossil fuel under the above conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing gas containing hydrogen, methane or carbon monoxide for gasifying fossil fuels and an apparatus for producing such gas.

[0002]

2. Description of the Related Art As a method for obtaining a gas containing at least one selected from the group consisting of hydrogen, methane and carbon monoxide from a fossil fuel, when coal is used as a raw material, Lu is used.
rgi method (reaction temperature: 1000 ° C, reaction pressure: 3MP
a), Koppers-Totzek method (reaction temperature: 1)
900 ° C., reaction pressure: 0.1 MPa). When using heavy oil to natural gas as raw materials, Sh
cell method (reaction temperature: 1500 ° C, reaction pressure: 6MP)
a), Texaco method (reaction temperature: 1500 ° C., reaction pressure: 8 MPa) and the like have been put to practical use. However, these methods cause fossil fuels to react with oxygen or air at high temperatures to produce a large amount of harmful nitrogen oxides and sulfur oxides, and to remove these harmful gases from the combustion exhaust gas. There is a problem that a separate facility is required.

In recent years, a method of gasifying coal or carbon-containing waste in supercritical water or subcritical water has been proposed (for example, Japanese Patent Application Laid-Open No. 11-72203). In these methods, relatively low temperatures (400 to 60) are used.
Since the gasification reaction is performed at 0 ° C.), generation of nitrogen oxides and the like is small, but there is a problem of corrosion of the material of the reaction vessel and deterioration of the catalyst due to severe corrosiveness of supercritical or subcritical water.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides hydrogen, methane and carbon monoxide under mild conditions in which the generation of harmful nitrogen oxides and the like is suppressed and the corrosion of the reaction vessel material and the deterioration of the catalyst do not occur. It is an object of the present invention to provide a method for producing a gas containing at least one selected from the group consisting of: and a gas producing apparatus suitable for carrying out the production method.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that gasification of fossil fuels in the supercritical state or subcritical state of carbon dioxide in the presence of water vapor. By carrying out, the generation of harmful nitrogen oxides and the like is suppressed, the corrosion of the reaction vessel material and the deterioration of the catalyst are also prevented, and the gas containing at least one selected from the group consisting of hydrogen, methane and carbon monoxide is increased. They have found that they can be manufactured efficiently, and have completed the present invention.

That is, the gist of the present invention is to provide (1) a step of gasifying at least a part of fossil fuel in the supercritical state or subcritical state of carbon dioxide in the presence of steam. , A method for producing a gas containing at least one selected from the group consisting of methane and carbon monoxide, and (2) a gasification reactor, a fossil fuel supply device for supplying a fossil fuel to the gasification reactor, A steam condensing device for condensing steam in the gas discharged from the gasification reactor, a carbon dioxide condensing device for condensing carbon dioxide in the gas discharged from the steam condensing device, and a carbon dioxide condensing device for the gasification reactor. Means for supplying carbon and water vapor, wherein at least a fossil fuel is provided in the gasification reactor in the supercritical state or subcritical state of carbon dioxide in the presence of water vapor. Some were it possible to gasification, hydrogen production apparatus gas containing at least one selected from the group consisting of methane and carbon monoxide, about.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fossil fuel used in the present invention is not particularly limited, and includes coal and coal derivatives,
Petroleum and petroleum derivatives, oil shale and oil sands, liquefied petroleum gas, natural gas, natural gas hydrate may be exemplified. Further, the fossil fuel to be used may be either one kind or a combination of two or more kinds.

[0008] Examples of coal include anthracite, bituminous coal, subbituminous coal, lignite, lignite, peat and the like. Examples of the coal derivative include coal coke, coal char (solid carbon), coal tar, coal gas, gas oil, COM (carbon oil mixture), CWM (carbon water mixture), and the like. Further examples include methane, benzene, toluene, xylene, phenol, naphthalene, anthracene, and methanol and dimethyl ether of coal synthesis gas derivatives, which are components of coal gas and gas light oil.

As for petroleum, crude oil, gasoline, naphtha,
Kerosene, light oil and heavy oil can be exemplified. Examples of the petroleum derivative include ethylene, propylene, butadiene, benzene, toluene, xylene, petroleum resin, petroleum coke, and petroleum pitch.

[0010] Oil shale refers to sedimentary rocks containing high molecular weight organic compounds, and oil sand refers to sandstones containing heavy and high viscosity crude oil.

The liquefied petroleum gas refers to a hydrocarbon gas containing propane, butane, or the like as a main component.

The natural gas refers to a hydrocarbon gas containing methane, ethane or the like as a main component, and the natural gas hydrate refers to a gas hydrate such as methane or ethane.

[0013] Among these fossil fuels, from the viewpoint of converting hard-to-use fuels to easy-to-use forms, from the group consisting of coal, coal char, coal tar, heavy oil, natural gas and natural gas hydrate. At least one selected is preferred.

From the viewpoint of improving the reactivity, the fossil fuel is preferably pulverized and supplied to the reaction. Specifically, the particle diameter is preferably 1 to 2000 μm, and more preferably 10 to 500 μm.
μm is more preferred. In addition, from the viewpoint of the above and supply of water vapor coexisting during gasification, it is preferable to provide a slurry in which finely divided fossil fuel is dispersed in water (hereinafter, referred to as a fossil fuel slurry). -50% by weight is preferred, and 20-45% by weight is more preferred. When the slurry concentration is within the above range, the fluidity is good, which is preferable. The particle size is not strict. For example, the fossil fuel may be pulverized by a conventional method, and may be adjusted to a desired particle size using a commercially available sieve or the like.

The water used in the present invention is not particularly limited as long as it does not inhibit the object of the present invention. For example, ultrapure water, pure water, ion-exchanged water, distilled water, ordinary tap water and the like can be mentioned.

In the present invention, at least a portion of the fossil fuel is gasified in the supercritical state or subcritical state of carbon dioxide in the coexistence of water vapor from the viewpoint of producing gas efficiently in a short time. A catalyst that further accelerates the process of gasifying fossil fuels (hereinafter referred to as gasification catalyst)
It is preferably carried out in the presence of Such a catalyst is not particularly limited, and examples thereof include a metal salt catalyst, a metal oxide catalyst, and a metal catalyst.

Examples of the metal salt catalyst include carbonates such as potassium carbonate, sodium carbonate and magnesium carbonate; chlorides such as nickel chloride and sodium chloride; sulfates such as potassium sulfate, sodium sulfate and iron sulfate; sodium hydroxide; Hydroxides such as iron oxide can be exemplified.

Examples of the metal oxide catalyst include iron oxide, copper oxide, aluminum oxide, chromium oxide, potassium oxide, sodium oxide, calcium oxide, cobalt oxide, and lanthanum oxide.

Examples of the metal catalyst include those in which molybdenum, vanadium, tungsten, nickel, cobalt and the like are supported on a metal oxide such as silicon oxide and alumina.

Among these gasification catalysts, potassium carbonate, sodium carbonate, iron oxide, aluminum oxide and the like are preferable from an economic viewpoint.

The above gasification catalysts may be used alone or in combination of two or more.

The gasification catalyst starts a reaction for gasification, for example, in a gasification reactor 5 of a gas producing apparatus of the present invention, which will be described later, in a reaction field for gasification of fossil fuel. They may be supplied in advance before use, or may be used by being dispersed and / or dissolved in the fossil fuel slurry. The gasification catalyst is preferably 1 to 100 parts by weight of the fossil fuel from the viewpoint of the rate of gasification reaction and economical viewpoint.
It is appropriate to use 50 parts by weight, more preferably 3 to 30 parts by weight.

Next, the gas production method of the present invention will be described with reference to the gas production apparatus of the present invention suitable for carrying out the production method. FIG. 1 schematically shows an example of the gas production apparatus of the present invention. The reaction operation can be performed in either a continuous mode or a batch mode. However, from an economic viewpoint, the continuous mode is more advantageous.

The gas production apparatus of the present invention supplies steam and carbon dioxide to the gasification reactor 5, the fossil fuel supply device 3, the steam condensation device 7, the carbon dioxide condensation device 9, and the gasification reactor 5, respectively. There is a means to do. In addition,
In FIG. 1, a means for supplying steam is not particularly shown, and a carbon dioxide supply device 4 is illustrated as a means for supplying carbon dioxide to the gasification reactor 5.

The gasification reactor 5 provides a reaction field for gasifying fossil fuels. The fossil fuel supply device 3 supplies fossil fuel to the gasification reactor 5 and is connected to the gasification reactor 5 via the fossil fuel supply line 1. The carbon dioxide supply device 4 is a device that supplies carbon dioxide to the gasification reactor 5, and the carbon dioxide supply line 2
Is connected to the gasification reactor 5 via a. The steam condensing device 7 is a device for condensing steam in the gas discharged from the gasification reactor 5, and is connected to the gasification reactor 5 via the gas connection line 6. The carbon dioxide condenser 9 is a device for condensing carbon dioxide in the gas discharged from the steam condenser 7, and is connected to the steam condenser 7 via a gas connection line 8.

The means for supplying water vapor to the gasification reactor 5 includes, for example, a means for supplying water directly into the gasification reactor 5 and a method for supplying fossil fuel as the fossil fuel slurry. A means for supplying water together with the fossil fuel by the fossil fuel supply device 3, and at least a part of the water condensed and separated by the steam condensing device 7 during the gasification reaction in the gasification step. And means for supplying water vapor by circulating the water in the inside of the fuel cell 5. In addition, such water may be directly converted into steam. As means for supplying carbon dioxide to the gasification reactor 5, other than means for supplying liquefied carbon dioxide by the carbon dioxide supply device 4, means for supplying liquefied carbon dioxide together with fossil fuel, and further for gasification During the reaction, means for circulating at least a part of the liquefied carbon dioxide condensed and separated by the carbon dioxide condensing device 9 into the gasification reactor 5 may be used. In addition, such liquefied carbon dioxide may be directly carbon dioxide. These means for supplying carbon dioxide or steam to the gasification reactor 5 can be appropriately combined.

The fossil fuel supply device 3 connected to the gasification reactor 5 via the fossil fuel supply line 1 is not particularly limited as long as the fossil fuel can be supplied over the pressure in the gasification reactor 5. Although not performed, for example, 10 to 30 MPa
A fossil fuel supply device having a supply capacity equal to or higher than the pressure is preferable. A gas compressor can be used when the fossil fuel is gas, and a pump can be used when the fossil fuel is liquid. The form of the gas compressor is not particularly limited, and a reciprocating type, a screw type and the like can be used. The form of the pump is not particularly limited, and a plunger type, a diaphragm type, a gear type, a rotary type, a spiral type and the like can be used. When the fossil fuel is solid, it is possible to provide a plurality of lock hoppers and sequentially charge them into the gasification reactor 5, and use a slurry pump to pulverize the solid fossil fuel into a slurry and use it as a slurry. It is also possible.

The carbon dioxide supply device 4 connected to the gasification reactor 5 via the carbon dioxide supply line 2 is not particularly limited as long as it can supply carbon dioxide over the pressure in the gasification reactor 5. But not for example 10-30
A carbon dioxide supply device having a supply capacity equal to or higher than the pressure of MPa is preferable. A gas compressor can be used for gaseous carbon dioxide, and a pump can be used for liquefied carbon dioxide. The form of the gas compressor is not particularly limited, and a reciprocating type, a screw type and the like can be used. The form of the pump is not particularly limited, and a plunger type, a diaphragm type, a gear type, a rotary type,
A spiral type can be used. In the case of dry ice, which is solid carbon dioxide, a plurality of lock hoppers can be provided and can be sequentially charged into the gasification reactor 5.

The supply timing and supply rate of each of the fossil fuel, water and carbon dioxide to the gasification reactor 5 are not particularly limited, and they are supplied into the gasification reactor 5 and the fossil fuel is gasified. The gasification reaction will be started at the stage where the desired conditions for the above have been prepared.

In a preferred embodiment of the gas producing method and the gas producing apparatus of the present invention, no oxidizing agent, for example, pure oxygen or oxygen-enriched air is supplied to the fossil fuel in the reaction field. In such a case, gasification is performed in the absence of oxygen other than the oxygen originally contained in the fossil fuel. According to this aspect, it is possible to eliminate problems caused by supplying the oxidizing agent to the reaction field, for example, conversion of undesired products (for example, aldehydes and carboxylic acids) due to oxidation of fossil fuels. However,
Since heat generated by combustion does not occur in the reaction field, it is necessary to supply heat to the reaction field in some form in order to secure desired reaction conditions in the reaction field. As a method of supplying heat, for example, (1) a method of supplying water and / or carbon dioxide to be supplied to a reaction field as superheated steam and / or superheated carbon dioxide and utilizing the sensible heat thereof, and (2) There are a method of supplying heat to the reaction field by external heat through the wall of the gasification reactor 5, (3) a method of combining them, and the like. Regarding (1), when water and carbon dioxide are supplied from the fossil fuel supply device 3 and the carbon dioxide supply device 4 or the like, they are heated to a desired temperature (for example, about 800 to 1500 ° C.) using an external heater or the like. (2) can be performed by using a gasification reactor capable of controlling the temperature in the gasification reactor.

In the gasification reactor 5, carbon dioxide is in a supercritical state (temperature: 31 ° C. or higher, carbon dioxide partial pressure: 7.3M).
The pressure and temperature are controlled so as to be in a subcritical state (temperature: 31 ° C. or more, carbon dioxide partial pressure: 5 MPa or more) or a subcritical state. Such carbon dioxide mainly consists of carbon dioxide supplied from the carbon dioxide supply device 4 at the beginning of the reaction, and after the start of the gasification reaction, the carbon dioxide supplied from the carbon dioxide supply device 4 and the fossil fuel It is composed of carbon dioxide generated at that time and carbon dioxide circulated in the gasification reactor 5 via the liquefied carbon dioxide circulation line 16. On the other hand, in the early stage of the reaction, mainly with fossil fuels or alone,
During the reaction, water circulated through the condensed water circulation line 15 is further supplied into the gasification reactor 5, and the fossil fuel is converted into an atmosphere in which water vapor coexists in a supercritical state or subcritical state of carbon dioxide. At least a portion will be gasified. Under such conditions, the gasification reactor 5
Inside, gasification by carbon dioxide and gasification by coexisting water vapor occur, and gasification of fossil fuel proceeds. In addition, hydrocracking and / or hydrodesulfurization using hydrogen derived from steam also occurs, and impurities including oxygen, sulfur, nitrogen, and the like contained in the fossil fuel are hydrocracked.

As described above, in the present invention, in the supercritical state or subcritical state of carbon dioxide, at least a part of the fossil fuel is gasified in the coexistence of water vapor. The generation of nitrogen oxides and sulfur oxides is suppressed, the corrosion of the reaction vessel material and the deterioration of the catalyst can be prevented, and the gas according to the present invention can be produced with high efficiency. The effect is obtained. In addition, nitrogen oxides and the decomposition products thereof can be efficiently extracted, and they can be easily removed together with condensed water and the like from the reaction site.

The supply amount of water and / or steam is preferably from 0.1 to 500 mol, more preferably from 1 to 50 mol, per mol of carbon molecules in the fossil fuel. In the reaction field, the coexisting water vapor is preferably in a molar ratio of 0.01 to 100 with respect to 1 of carbon dioxide.
More preferably, it is 1 to 10. As the reaction temperature,
400 ° C to 1600 ° C, preferably 450 ° C to 1000 ° C
C is more preferable, and 500 to 800 C is particularly preferable.
The reaction temperature is measured as the outlet temperature of the gasification reactor 5. Such conditions are preferable from the viewpoint that the gas according to the present invention is obtained with high efficiency and the reaction conditions are relatively mild with little corrosion of the gasification reactor 5. The partial pressure of carbon dioxide in the gasification reactor 5 is preferably 5 MPa to 3 MPa.
It is appropriately selected from 0 MPa, more preferably 6 MPa to 20 MPa. Within such a range, the supercritical effect is sufficient, which is preferable from an economic viewpoint. Further, the water vapor partial pressure of water vapor coexisting in a supercritical state or a subcritical state of carbon dioxide is preferably 0.01 to 100, more preferably 0.1 to 10 with respect to the carbon dioxide partial pressure. It is appropriately selected from among them. Within such a range, it is preferable from the viewpoint of economical as well as the viewpoint that the gasification reaction is favorably performed. In addition, the total pressure is preferably 8 MPa to 40 MPa, more preferably 10 MPa to
It is appropriately selected from 30 MPa. Such reaction temperature,
The reaction proceeds spontaneously under the reaction pressure, but if desired, a gasification catalyst such as the above-mentioned metal salt catalyst, metal oxide catalyst, or metal catalyst may be used as appropriate. In this way, in the supercritical state or subcritical state of carbon dioxide, by gasifying at least a part of the fossil fuel in the presence of water vapor, gasification can be performed under mild reaction conditions.

The average residence time of the gasification reactor 5 is as follows:
There is no particular limitation so long as the gas composition reaches the equilibrium time under the selected reaction temperature and reaction pressure, but a shorter one is preferable from an economic viewpoint. Usually, it is appropriately selected from the range of preferably 0.1 second to 5 hours, more preferably 1 second to 1 hour.

The material of the gasification reactor 5 is not particularly limited as long as it can withstand the above-mentioned reaction temperature and reaction pressure. For example, Hastelloy alloy, titanium alloy, Mo
Alloy, Ni-Cr alloy, stainless steel, stainless clad steel, Hastelloy clad steel, ceramic lining steel, etc., from the viewpoint of balance between heat resistance, corrosion resistance and economy, stainless steel, stainless clad steel, Hastelloy clad steel and ceramic Lining steel is preferred. In the present invention, in the supercritical state or subcritical state of carbon dioxide, a step of gasifying at least a part of the fossil fuel in the presence of water vapor is performed. Alternatively, stainless steel, which is difficult to use when subcritical water is used, can also be used. Further, the shape of the gasification reactor 5 is not particularly limited, and a tube type, a tank type, or the like can be used.

The gasification reactor 5 is connected via a gas connection line 6.
In the steam condensing device 7 connected to the steam, the steam in the reaction gas is cooled by a heat exchanger, and the steam is separated as condensed water. The condensed water separated by the steam condensing device 7 includes:
Toxic substances such as sulfur oxides, nitrogen oxides, and heavy metals may be contained and can be removed by the toxic substance discharge line 17. At least a part of the condensed water is circulated in the gasification reactor 5. The amount of condensed water circulated is limited to such an extent that the harmful substances are not concentrated in the gasification reactor 5, and the insufficient water may be supplied into the gasification reactor 5 by, for example, fossil fuel or alone.

The cooling medium supplied to the steam condensing device 7 includes, for example, tap water, industrial water, seawater, recooled water,
Groundwater, chiller water and the like can be mentioned. The temperature of the cooling medium is not particularly limited as long as it is equal to or lower than the saturation temperature of steam at the operating pressure. The form of the steam condenser 7 is not particularly limited, and a shell & tube type, a U-tube type, a spiral type, or the like can be used.

Gasification reactor 5 for at least part of condensed water
The circulation into the inside is performed through a condensed water circulation line 15 by a condensed water circulation pump 13 connected to the steam condensing device 7 through a condensed water line 11. Adjustment of the pH of the condensed water is not particularly necessary, and it may be appropriately neutralized when the acidity is excessively acidic. The form of the condensed water circulation pump 13 is not particularly limited, and a plunger type, a diaphragm type, a gear type, a rotary type, a spiral type, and the like can be used. In addition, a heat exchanger (not shown) may be provided between the gas connection line 6 and the condensed water circulation line 15 to improve thermal efficiency.

In the carbon dioxide condensing device 9 connected to the steam condensing device 7 via the gas connection line 8, the carbon dioxide in the reaction gas is cooled by a heat exchanger, and the carbon dioxide is separated as liquefied carbon dioxide. Examples of the cooling medium supplied to the carbon dioxide condenser 9 include dry ice, liquefied nitrogen, cooling brine, chiller water, industrial water,
Groundwater, tap water and the like can be mentioned. If the temperature of the cooling medium is below the saturation temperature of carbon dioxide at the operating pressure,
There is no particular limitation. The form of the carbon dioxide condensing device 9 is not particularly limited, and a shell & tube type, a U-tube type, a spiral type, or the like can be used.

At least a part of the liquefied carbon dioxide is circulated into the gasification reactor 5 by a liquefied carbon dioxide circulation pump 14 connected to a carbon dioxide condenser 9 through a liquefied carbon dioxide line 12. Circulation line 1
6 is performed. The form of the liquefied carbon dioxide circulation pump 14 is not particularly limited, and a plunger type, a diaphragm type, a gear type, a rotary type, a spiral type and the like can be used. Further, a heat exchanger (not shown) may be provided between the gas connection line 8 and the liquefied carbon dioxide circulation line 16 in order to improve thermal efficiency.

As described above, in the step of gasifying the fossil fuel, at least a part of the water condensed by the steam condensing device 7 or the carbon dioxide condensing device 9 is condensed in the gasification reactor 5. The condensed water is circulated together with at least a part of the liquefied carbon dioxide through the condensed water circulation line 15, or each of the condensed water circulation line 15 and the liquefied carbon dioxide circulation line 16, and water insufficient for the reaction is supplied together with the fossil fuel or alone. Thus, an atmosphere in which water vapor coexists in a supercritical state or a subcritical state of carbon dioxide can be obtained.

Finally, a gas containing at least one selected from the group consisting of hydrogen, methane and carbon monoxide from which water vapor and carbon dioxide have been removed is supplied from a gas discharge line 10 connected to the carbon dioxide condenser 9. Obtainable. According to such a gas production method and production apparatus, the gasification rate can be preferably 20 to 100%, more preferably 40 to 100%. The gasification rate (%) is calculated by the following equation:

[0043]

(Equation 1)

Can be obtained by In the formula, the fossil fuel (g) after gasification refers to the residual carbon content, and when the fossil fuel contains ash, it refers to the total amount of the residual carbon content and the ash content.

As a further embodiment of the gas production method of the present invention, after a part of the fossil fuel is gasified in the absence of oxygen other than the oxygen contained in the fossil fuel, the residue of the fossil fuel is removed. The carbon dioxide is subjected to a gasification step in a supercritical state or a subcritical state. That is, after carbonizing the fossil fuel, the step of gasifying at least a part of the fossil fuel as described above is performed. According to this aspect, a desired gas can be obtained more efficiently.

FIG. 2 schematically shows an entire manufacturing apparatus suitable for carrying out this embodiment. The apparatus further includes a reactor (a dry distillation reactor) for gasifying a part of the fossil fuel in the absence of oxygen other than oxygen contained in the fossil fuel, in addition to the apparatus illustrated in FIG. A part of the fossil fuel supplied from the fossil fuel supply device is gasified in advance and then supplied to the gasification reactor. In addition, gas may be produced by performing dry distillation separately and using the apparatus shown in FIG.

The apparatus of FIG. 2 is different from the apparatus of FIG. 1 in that a dry distillation reactor 1 is provided between a fossil fuel supply device 3 and a gasification reactor 5.
The dry distillation reactor 18 is connected to the fossil fuel supply device 3 via the fossil fuel supply line 1, and the dry distillation reactor 18 is connected to the gasification reactor 5 via the fossil fuel transfer line 19. ing. Further, the dry distillation reactor 18 is connected to the gas discharge line 10 via a gas connection line 20. In the present apparatus, while the fossil fuel is supplied to the gasification reactor 5, the fossil fuel can be gasified in the absence of oxygen other than oxygen contained in the fossil fuel. That is,
A liquid distillation reactor 18 gasifies a liquid and / or solid fossil fuel by pyrolysis to obtain a gas containing at least one selected from the group consisting of hydrogen, methane and carbon monoxide. Gasification of liquid and / or solid fossil fuel, which is the residue of gasification, in the supercritical or subcritical state of carbon dioxide in the presence of water vapor, consisting of hydrogen, methane and carbon monoxide A gas containing at least one selected from the group can be obtained. In this case, the pyrolysis gas discharged from the carbonization reactor 18 is obtained by removing water from the gas discharged from the gasification reactor 5 by the steam condenser 7 and removing carbon dioxide by the carbon dioxide condenser 9. The target gas can be mixed with the gas.

The inside of the dry distillation reactor 18 is operated in an atmosphere containing no oxygen in order to prevent oxidation of the produced gas. However, usually, thermal decomposition is performed in an atmosphere of carbon dioxide or nitrogen. The operating pressure in the dry distillation reactor 18 is not particularly limited, but from an economic viewpoint, a lower pressure is preferable, and a pressure of 1 MPa or less is generally preferable. The operating temperature in the carbonization reactor is not particularly limited as long as it is equal to or higher than the temperature at which thermal decomposition starts, but from an economic viewpoint, a lower temperature is preferable, and a temperature of usually 1000 ° C. or lower is usually preferable.

The gas according to the present invention, which can be obtained as described above, is suitably used for boiler fuel, gas turbine fuel, gas engine fuel and the like.

[0050]

The present invention will be described in more detail with reference to the following examples. The examples and comparative examples were carried out using the same apparatus as the apparatus shown in FIG.

Example 1 As a fossil fuel, Australian Newlands coal (water: 8.42% by weight, ash content: 12.28% by weight, volatile matter: 25.96% by weight, fixed carbon: 53.34% by weight) was used. Using. The Newlands charcoal is crushed by 100-500 μm
And dried at 107 ° C. for 1 hour at normal pressure.
Coal char was prepared by dry distillation under a nitrogen atmosphere at 0.5 MPa at 50 ° C. for 2 hours. Further, the coal char was finely pulverized to 10 μm to 100 μm by a colloid mill. 3.78 g of the coal char was dispersed in a solution of 1.0 g of potassium carbonate as a gasification catalyst in 18 g of water to obtain a coal char slurry. The gasification reactor has an inner diameter of 10 mm and a length of 300 mm (internal volume 23.6 cm
³ ) Stainless steel (SUS316) was used. Coal char slurry liquid is supplied by a piston pump.
2.28 g / h (water 1.8 g / h, potassium carbonate 0.1
g / h, coal char 0.38 g / h) and fed into the gasification reactor while heating to 650 ° C. with a heater. Carbon dioxide was supplied into the gasification reactor while liquefied carbon dioxide was heated to 650 ° C. by a heater at a supply rate of 4.4 g / h by a positive displacement pump. The gasification reactor has a steady state at an outlet temperature of 640 ° C.
The temperature was controlled at 660 ° C. and the total pressure was 17 to 19 MPa. The obtained reaction gas was cooled with tap water, condensed water was separated, and the whole amount was purged. The reaction gas from which the condensed water was separated was cooled with dry ice, and carbon dioxide was separated as liquefied carbon dioxide. The reaction gas after phase separation of water and carbon dioxide was adjusted to normal pressure with a pressure reducing valve, and the flow rate was measured with a gas flow meter. The solid content remaining in the system was measured by evaporating volatiles from the solid content present in the separated condensed water and liquefied carbon dioxide after the end of the continuous experiment. Of the 0.38 g / h coal char charged into the gasification reactor, 43% (0.163 g / h) was gasified (gasification rate).
The gas composition was 31 mol% of methane, 20 mol% of hydrogen, 17 mol% of carbon monoxide, and 32 mol% of carbon dioxide (separated as liquefied carbon dioxide). Also, nitrogen oxides and sulfur oxides were not detected in this gas.
The remaining solid content was 0.317 g / h, of which 0.163 g / h of residual carbon and 0.05 of ash content
4 g / h and potassium carbonate 0.1 g / h. From the estimation of the mole fraction in the reaction gas, the average residence time of the gasification reactor was 60 minutes, and the partial pressure of carbon dioxide was 8.5 MPa to
It was calculated to be 9.5 MPa (supercritical state of carbon dioxide). In addition, when the gasification reactor was operated for about 100 hours and checked for corrosion, no corrosion of the reactor was found.

Comparative Example 1 An experiment was carried out under the same conditions as in Example 1 except that the total pressure was 5 MPa to 6 MPa, and a reaction gas was obtained. Of the 0.38 g / h coal char charged to the gasification reactor, 6.8% (0.026 g / h) was gasified, and the gas composition was methane 28 mol%, hydrogen 23 mol%, monoxide. It became 19 mol% of carbon and 30 mol% of carbon dioxide (separated as liquefied carbon dioxide). The remaining solid content is 0.
454 g / h, of which 0.30 g was residual carbon.
/ H, ash content was 0.054 g / h, and potassium carbonate was 0.1 g / h. From the estimation of the mole fraction in the reaction gas, the average residence time of the gasification reactor was 100 minutes,
The carbon dioxide partial pressure was calculated to be 2.5 MPa to 3 MPa (not the subcritical and supercritical states of carbon dioxide).

Comparative Example 2 A medium for dispersing coal char was changed from 18 g of water to liquid nitrogen 2
An experiment was performed under the same conditions as in Example 1 except that the amount was changed to 8 g, and a reaction gas was obtained. 1.6% (0.0%) of the 0.38 g / h coal char charged into the gasification reactor
06 g / h), and the gas composition was 80 mol% of carbon monoxide and 20 mol% of carbon dioxide (separated as liquefied carbon dioxide), and methane and hydrogen were not detected. The remaining solid content was 0.474 g / h, of which 0.32 g / h of residual carbon and 0.02 g of ash
54 g / h and potassium carbonate were 0.1 g / h. From the estimation of the mole fraction in the reaction gas, the average residence time of the gasification reactor was 60 minutes, and the partial pressure of carbon dioxide was 8.5 MPa.
It was calculated to be ９9.5 MPa (supercritical state of carbon dioxide).

[0054]

According to the present invention, the generation of harmful nitrogen oxides and the like is suppressed, and a gas containing at least one selected from the group consisting of hydrogen, methane, and carbon monoxide is used to corrode the material of the reaction vessel, It can be manufactured with high efficiency under mild conditions that do not cause catalyst deterioration.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one example of a gas producing apparatus of the present invention.

FIG. 2 is a schematic explanatory view showing one example of a gas producing apparatus of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fossil fuel supply line 2 carbon dioxide supply line 3 fossil fuel supply device 4 carbon dioxide supply device 5 gasification reactor 6 gas connection line 7 steam condensation device 8 gas connection line 9 carbon dioxide condensation device 10 gas discharge line 11 condensed water line 12 liquefied carbon dioxide line 13 condensed water circulation pump 14 liquefied carbon dioxide circulation pump 15 condensed water circulation line 16 liquefied carbon dioxide circulation line 17 toxic substance discharge line 18 dry distillation reactor 19 fossil fuel transfer line 20 gas connection line

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Koji Amano 4-1 Egasakicho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Energy and Environment Laboratory, Tokyo Electric Power Co., Inc. 17 Kanagawa New Technology Research Institute, Teranimachi Co., Ltd. (72) Inventor Atsushi Sakai 17 Nakatsuji Minamimachi, Shimogyo-ku, Kyoto, Kyoto, Japan Inside Kansai New Technology Research Co., Ltd. 17 Kanno-ji Minamicho, Ward, Kansai New Technology Research Institute, Inc. EA09 4G069 AA06 BB16B BC03B CC19 DA02 4G140 EA01 EA03 EA04 EA06 EA09

Claims (14)

[Claims] 1. A process comprising gasifying at least a part of a fossil fuel in the supercritical state or subcritical state of carbon dioxide in the presence of water vapor, comprising hydrogen, methane and carbon monoxide. A method for producing a gas containing at least one member selected from the group. 2. The method according to claim 1, wherein gasification is performed in the absence of oxygen other than oxygen contained in the fossil fuel. 3. The production method according to claim 1, wherein gasification is performed in the presence of a catalyst that promotes gasification of fossil fuel. 4. After gasifying a part of the fossil fuel in the absence of oxygen other than oxygen contained in the fossil fuel, the gas is subjected to a gasification process in a supercritical state or a subcritical state of carbon dioxide. The method according to claim 1. 5. The method according to claim 1, wherein water vapor and carbon dioxide contained in a gas containing at least one selected from the group consisting of hydrogen, methane and carbon monoxide are condensed and separated by cooling. Manufacturing method. 6. A method for circulating at least a part of water condensed and separated or at least a part of water condensed and separated and at least a part of liquefied carbon dioxide condensed and separated to a supercritical state or a subcritical state of carbon dioxide. The production method according to claim 5, wherein the atmosphere is made such that water vapor coexists in a critical state. 7. The fossil fuel is at least one selected from the group consisting of coal, coal char, coal tar, heavy oil, natural gas and natural gas hydrate.
7. The production method according to any one of claims 6 to 6. 8. The method according to claim 1, wherein the coexisting water vapor is in a molar ratio of 0.01 to 100 with respect to 1 carbon dioxide. 9. A gasification reactor, a fossil fuel supply device for supplying a fossil fuel to the gasification reactor, a steam condensation device for condensing steam in gas discharged from the gasification reactor, A carbon dioxide condensing device for condensing carbon dioxide in gas discharged from the steam condensing device; and a means for supplying carbon dioxide and water vapor to the gasification reactor. A gas containing at least one selected from the group consisting of hydrogen, methane and carbon monoxide, capable of gasifying at least a portion of a fossil fuel in the supercritical state or subcritical state of water in the presence of water vapor Manufacturing equipment. 10. A fossil fuel supplied from a fossil fuel supply device, further comprising a reactor for gasifying a part of the fossil fuel in the absence of oxygen other than oxygen contained in the fossil fuel. The production apparatus according to claim 9, wherein after the section has been gasified in advance, it can be supplied to a gasification reactor. 11. The gasification reactor according to claim 9, wherein the means for supplying water vapor to the gasification reactor is to supply water into the gasification reactor together with fossil fuel by a fossil fuel supply device.
Manufacturing apparatus according to the above. 12. The production apparatus according to claim 9, wherein the means for supplying carbon dioxide to the gasification reactor supplies liquefied carbon dioxide into the gasification reactor. 13. The gasification reactor according to claim 9, wherein the means for supplying steam to the gasification reactor circulates at least a part of the water condensed and separated by the steam condensation device into the gasification reactor. The manufacturing apparatus according to the above. 14. The method for supplying carbon dioxide to a gasification reactor is to circulate at least a part of liquefied carbon dioxide condensed and separated by a carbon dioxide condenser into the gasification reactor. 14. The manufacturing apparatus according to any one of 9 to 13.