JP4136624B2 - Liquid fuel reforming method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention may be used in such a fuel cell power plant, the kerosene or gasoline relates to a modified method and apparatus for steam reforming.
[0002]
[Prior art]
A fuel cell power generation device is a device that directly converts chemical energy of fuel into electrical energy without passing through mechanical energy or thermal energy, and can achieve high energy efficiency. As a well-known form of a fuel cell, a pair of electrodes are arranged with an electrolyte layer in between, a fuel gas containing hydrogen is supplied to one electrode (anode side), and oxygen is supplied to the other electrode (cathode side). Is supplied, and an electromotive force is obtained by utilizing an electrochemical reaction occurring between the two electrodes.
[0003]
Below, an equation representing an electrochemical reaction occurring in the fuel cell is shown. (1) represents the reaction on the anode side, (2) represents the reaction on the cathode side, and the reaction represented by the formula (3) proceeds in the entire fuel cell.
[0004]
H ₂ → 2H ++ 2e- (1)
1 / 2O ₂ + 2H ++ 2e- → H ₂ O (2)
H ₂ + 1 / 2O ₂ → H ₂ O (3)
Fuel cells are classified according to the type of electrolyte used. Among these fuel cells, solid polymer fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, etc. It is possible to use an oxidant gas or carbon dioxide containing carbon dioxide. Therefore, in these fuel cells, normally, air is used as an oxidant gas, and a hydrogen-rich gas generated by steam reforming a hydrocarbon-based raw fuel gas such as natural gas or city gas is used as a fuel gas.
[0005]
Therefore, in a fuel cell power generation apparatus including such a fuel cell, a reformer and a carbon monoxide converter are provided, and the raw fuel is reformed by the reformer and the carbon monoxide converter. Gas is being generated. Equation (4) below shows the reforming reaction of methane in the reformer.
[0006]
CH ₄ + H ₂ O → 3H ₂ + CO (+206.14 KJ / mol: endothermic reaction) (4)
As shown in the above formula (4), the reforming reaction of methane is an endothermic reaction. Therefore, after adding water vapor to methane, the granular reforming catalyst is formed by combustion exhaust gas obtained by burning fuel off-gas from the fuel cell. By maintaining the temperature at 600 to 700 ° C., a reformed gas rich in hydrogen is generated.
[0007]
This reformed gas leaving the reformer is fed to a carbon monoxide converter to reduce the carbon monoxide in the reformed gas, where the carbon monoxide is reduced to less than 1% and is in phosphoric acid form. In the case of a fuel cell (PAFC), this gas can be introduced into the fuel cell to generate power. The following formula (5) shows the carbon monoxide conversion reaction in the carbon monoxide converter.
[0008]
CO + H ₂ O → H ₂ + CO ₂ (-41.17 KJ / mol: exothermic reaction) (5)
As shown in the formula (5), the carbon monoxide modification reaction is an exothermic reaction, and thus cooling is required to maintain the modification reaction temperature at 160 to 250 ° C.
[0009]
On the other hand, the polymer electrolyte fuel cell (PEFC) has a low operating temperature of 60 to 80 ° C., so if carbon monoxide is present in the reformed gas, it becomes a catalyst poison and deteriorates its performance. The carbon monoxide needs to be further reduced, so that the reformed gas is fed to the carbon monoxide remover, where the carbon monoxide is reduced to 10 ppm or less. Equation (6) below shows the selective oxidation reaction of carbon monoxide in the carbon monoxide remover.
[0010]
CO + 1 / 2O ₂ → CO ₂ (-257.2 KJ / mol: exothermic reaction) (6)
As shown in Formula (6), since the selective oxidation reaction of carbon monoxide is an exothermic reaction, cooling is required to maintain the selective oxidation reaction temperature at 160 to 230 ° C.
[0011]
As described above, since the polymer electrolyte fuel cell (PEFC) has a low reaction temperature, unlike the phosphoric acid fuel cell (PAFC) (reaction temperature of about 180 ° C.), its calorific value generates steam for reforming. Since it cannot be generated, it is necessary to generate it in the reforming equipment. The amount of heat for generating steam is usually obtained by heat exchange with the combustion exhaust gas after leaving the reformer.
[0012]
By the way, as the hydrocarbon-based raw fuel, liquid fuels such as butane, propane, naphtha, and methanol are used in addition to the gaseous fuel such as natural gas and city gas. Since these liquid fuels vaporize relatively easily, they are generally gasified and steam reformed.
[0013]
Patent Document 1 discloses an example of an apparatus that gasifies and steam reforms a liquid fuel containing 58% by weight of methanol and 42% by weight of water. In the case of this apparatus, the liquid fuel evaporator and the reformer are integrated, and a configuration is adopted in which the heat of the combustion exhaust gas of the burner is supplied to both the evaporator and the reformer.
[0014]
In addition to the above, as a liquid fuel, recently, since it is easy to transport and inexpensive, a gas containing hydrogen generated by steam reforming a liquid raw fuel such as kerosene or gasoline is used as a fuel gas. Methods are also being considered.
[0015]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 61-153957 (pages 2-5, FIGS. 1, 5, 6)
[0016]
[Problems to be solved by the invention]
By the way, the liquid raw fuels such as kerosene and gasoline described above contain a component having a relatively high boiling point, and there is a problem that the liquid raw fuels are incombustible as compared with liquid fuels such as butane, propane, naphtha, and methanol. For example, kerosene is a hydrocarbon-based fuel that is refined from petroleum and has a fraction that is liquid at room temperature of 150 ° C. to 270 ° C.
[0017]
In order to steam-reform kerosene, the sulfur content of 80 wtppm or less previously contained in kerosene is removed, mixed with water for reforming steam, and heated to 270 ° C or higher, preferably 300 ° C or higher to vaporize. Or vaporized using steam enthalpy after mixing with steam heated to 350 ° C. or higher, and then reformed to hydrogen and carbon monoxide in a reformer.
[0018]
Further, since the reforming reaction of kerosene is an endothermic reaction, the granular reforming catalyst is maintained at 600 to 700 ° C. near the reformed gas outlet by the combustion exhaust gas obtained by burning the fuel off-gas from the fuel cell with the reformer burner. As a result, the steam reforming reaction is continued. The temperature near the inlet of the reformed raw fuel in the reforming catalyst layer is about 300 ° C.
[0019]
FIG. 3 shows an example of a schematic configuration of a fuel cell power generation apparatus under examination in the past using this type of kerosene as a raw fuel. In FIG. 3, the raw fuel from which the sulfur content has been removed in the desulfurizer 1 is mixed with the reforming steam water, then supplied to the vaporizer 2 as the reformed raw fuel, and after being vaporized, the catalyst of the reformer 3 It is supplied to the reaction layer 3a. In the catalytic reaction layer 3a, the hydrogen-rich reformed gas is formed by the steam reforming reaction, and then supplied to the carbon monoxide converter 4 to increase the hydrogen concentration by the carbon monoxide conversion reaction. The carbon monoxide is supplied to the carbon monoxide remover 5 together with an amount of air, and after the carbon monoxide is reduced to 10 ppm or less by the carbon monoxide selective oxidation reaction, it is supplied to the fuel cell 6.
[0020]
In FIG. 3, the heat source used for vaporizing the reformed raw fuel containing water in the vaporizer 2 is a burner 7 provided in the reformer 3, and the fuel off-gas from the fuel cell 6 is converted into air by the combustion air blower 8. Since it is combustion exhaust gas (temperature is about 300 ° C.) after burning and giving the combustion heat for the endothermic methane steam reaction, the temperature of the reformed raw fuel mixture is at most 250 ° C. The temperature can only be raised to a certain extent.
[0021]
When the raw fuel gas such as city gas, the temperature in the vicinity of the inlet of the city gas in the reforming catalyst layer is sufficient in this extent, the raw fuel, in the case of kerosene if example embodiment, kerosene Since the components having a high boiling point contained in the catalyst condense and cover the catalyst surface, or the carbon component adheres to the reaction area by reducing the reaction area, the mixture of kerosene and steam is It is necessary to raise the temperature to at least about 300 ° C. and then supply it to the reformer. Therefore, an electric heater 9 is provided at the outlet of the vaporizer 2 as shown in FIG. In this case, there is a problem that the power generation efficiency is reduced by the amount of power consumed in the electric heater 9.
[0022]
The present invention has been made to solve the above problems, and an object of the present invention is to raise the temperature of a mixture of kerosene or gasoline and reforming steam to at least about 300 ° C. without using an electric heater. It is an object of the present invention to provide a liquid fuel reforming method and apparatus with high efficiency and high performance.
[0023]
[Means for Solving the Problems]
To attain the above object, the present invention is a kerosene or gasoline, in the reforming process for steam reforming in the catalyst reaction layer of the reformer,
The kerosene or a mixture of gasoline and water is primarily heated by the combustion exhaust gas of the reformer heating burner to form an air-fuel mixture, and this air-fuel mixture is at least a high-boiling component contained in the kerosene or gasoline After the secondary heating by heat transfer from the reformer to 300 ° C. or more to prevent condensation of the reformer, the reforming is performed by supplying to the catalytic reaction layer of the reformer (Invention of Claim 1) .
[0024]
According to the above reforming method, it is possible to raise the temperature of the primary heated air-fuel mixture to 300 ° C. or higher without using an electric heater, and to provide a highly efficient and high performance liquid fuel reforming method. Note that, as disclosed in Patent Document 1, the heat of the combustion exhaust gas of the burner is supplied to both the evaporator and the reformer, and the primary heating and the secondary heating are simultaneously achieved in the evaporator. Is also possible. However, in this case, since the heat of the combustion exhaust gas cannot be effectively used step by step according to the temperature level, the overall thermal efficiency is lowered. Therefore, there is a difficulty as a method for reforming kerosene or the like, which is the subject of the present invention.
[0025]
Further, as an apparatus for carrying out the reforming method, the invention of claim 2 is preferable. That is, a reformer for carrying out the reforming method according to claim 1 , wherein a reformer having a catalytic reaction layer and a heating burner, and kerosene or gasoline are used by combustion exhaust gas of the heating burner. and a vaporizer to produce a mixed gas mixture is heated primary water, further, the reformer is intended to comprise a heat transfer means for secondary heating the mixture (the second aspect of the present invention ).
[0026]
As an embodiment of the invention of claim 2, the inventions of claims 3 to 5 are preferable. That is, in the reformer according to claim 2 , the heat transfer means is a heat exchanger provided on the wall surface of the heating burner (invention of claim 3 ). Furthermore, in the reforming apparatus according to claim 2 , the heat transfer means is a heat exchanger provided in a gas channel after reforming in the catalytic reaction layer (invention of claim 4 ). Furthermore, in the reforming apparatus according to claim 3 or 4 , the heat exchanger includes a spiral pipe through which the mixed gas or the gas after reforming flows (Invention of claim 5 ). .
[0027]
According to the structure of the said embodiment, the heat dissipation from the surface of the reformer containing a burner falls, and the effect which further improves thermal efficiency is also acquired.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention will be described below with reference to the drawings.
[0029]
FIG. 1 shows a schematic configuration of a fuel cell power generator including a kerosene reformer according to an embodiment of the present invention. The members having the same functions as those in FIG.
[0030]
In the embodiment shown in FIG. 1, a spiral pipe 11 is wound around the wall of the reformer burner 7, and a mixture of kerosene and reforming steam that has come out of the vaporizer 2 is passed therethrough for secondary heating. Later, it is supplied to the reformer 3. In normal operation, the outer wall of the reformer burner is maintained at about 500 ° C. Therefore, according to the above configuration, the mixture of kerosene and reforming steam is heated to about 400 ° C. and is completely gaseous. Since the components are supplied to the reformer in a state, the reforming reaction can be performed satisfactorily without condensing unvaporized components and adversely affecting the reforming performance. Moreover, according to such a structure, the effect that the thermal radiation amount from the surface of the reformer burner falls and thermal efficiency improves is also acquired.
[0031]
In addition, in FIG. 1, although the structure which winds a pipe helically around the wall surface of a reformer burner was shown, the wall surface of a reformer burner is made into a two-layer jacket shape, and kerosene and The same effect can be obtained even when the mixture of reforming steam is passed.
[0032]
Next, the embodiment of FIG. 2 will be described. The members having the same functions as those in FIG.
[0033]
In the embodiment of FIG. 2, a spiral pipe 12 is wound around the wall of the reformed gas flow path, and the mixture of kerosene and reforming steam that has come out of the vaporizer 2 is passed through this to the reformer. Supply. In a normal operation, the reformed gas exits the reforming catalyst layer at about 600 to 700 ° C., then is cooled while heating the reforming catalyst layer, and is led out at about 350 ° C. to be converted into the carbon monoxide converter 4 To be introduced.
[0034]
Therefore, since the wall surface of the gas inlet of the post-reforming gas channel is maintained at 500 ° C. or higher, according to the above configuration, the mixture of kerosene and reforming steam is heated to about 400 ° C., Since the gas is completely supplied to the reformer, the reforming reaction can be performed satisfactorily as in the embodiment of FIG. Moreover, according to such a structure, the effect that the thermal radiation amount from the surface of a reformer falls and thermal efficiency improves is also acquired. In addition, in FIG. 2, although the structure which winds a helical pipe around the wall surface of a gas channel after a reforming was shown, the wall surface of the gas channel after a reforming is made into a two-layer jacket shape, and between the inner and outer jackets, A configuration in which a mixture of kerosene and reforming steam is also allowed to flow.
[0035]
【The invention's effect】
As described above, according to the present invention, a kerosene or gasoline, in the reforming process for steam reforming in the catalyst reaction layer of the reformer, a mixture of the kerosene or gasoline and water, heating of the reformer The mixture is primarily heated by the combustion exhaust gas of the burner to form an air-fuel mixture, and the air-fuel mixture is further removed from the reformer to at least 300 ° C. in order to prevent condensation of high-boiling components contained in the kerosene or gasoline. After the secondary heating by heat transfer, the reforming by supplying to the catalytic reaction layer of the reformer,
As an apparatus for carrying out the method, a reformer having a catalytic reaction layer and a heating burner, and a mixture of kerosene or gasoline and water are primarily heated by a combustion exhaust gas of the heating burner to generate an air-fuel mixture. A reformer, and further, the reformer includes a heat transfer means for secondary heating of the mixture.
A mixture of kerosene or gasoline and steam for reforming can be heated to at least 300 ° C. or higher without using an electric heater, and a highly efficient and high performance liquid fuel reforming method and apparatus can be provided. .
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a fuel cell power generation device including a kerosene reformer according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a fuel cell power generation device according to an embodiment different from FIG. FIG. 3 is a schematic configuration diagram of a conventional fuel cell power generator.
1: desulfurizer, 2: vaporizer, 3: reformer, 3a: catalytic reaction layer, 4: carbon monoxide converter, 5: carbon monoxide remover, 6: fuel cell, 7: burner, 11, 12 : Spiral pipe.

Claims (5)

Kerosene or gasoline, in the reforming process for steam reforming in the catalyst reaction layer of the reformer,
The kerosene or a mixture of gasoline and water is primarily heated by the combustion exhaust gas of the reformer heating burner to form an air-fuel mixture, and this air-fuel mixture is at least a high-boiling component contained in the kerosene or gasoline A liquid fuel which is reformed by supplying it to the catalytic reaction layer of the reformer after secondary heating to 300 ° C. or more for preventing condensation of the reformer by heat transfer from the reformer Reforming method. A reforming apparatus for carrying out the reforming method according to claim 1 , wherein a reformer having a catalytic reaction layer and a heating burner, and kerosene or gasoline and water are produced by combustion exhaust gas of the heating burner. A reformer for liquid fuel, wherein the reformer further comprises heat transfer means for secondary heating of the mixture. . 3. The reforming apparatus according to claim 2 , wherein the heat transfer means is a heat exchanger provided on a heating burner wall surface. 3. The reformer according to claim 2 , wherein the heat transfer means is a heat exchanger provided in a gas channel after reforming in the catalytic reaction layer. In the reforming apparatus according to claim 3 or 4, wherein the heat exchanger reformer of a liquid fuel, characterized in that it comprises a helical pipe for Tsuryu the gas after the air-fuel mixture or modification.

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