JP2004175621A - Method and apparatus for reforming liquid fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high efficiency, high performance liquid fuel reforming method and apparatus for heating a gaseous mixture of hardly evaporating liquid crude fuel such as kerosene and reforming steam at least to about 300°C without using an electric heater. <P>SOLUTION: In the reforming method of steam-reforming the hardly evaporating liquid crude fuel such as kerosene or gasoline in a catalytic reaction layer, a mixture of kerosene and water, for example, is primarily heated by a waste combustion gas from a reforming burner 7 to prepare a gaseous mixture. The obtained gaseous mixture is secondarily heated, for example, to ≥300°C by the heat transfer from a reformer 3 to prevent at least the condensation of high boiling point component contained in the kerosene, and is supplied to the catalytic reaction layer to be reformed. The apparatus is provided with the reformer 3 having the catalytic reaction layer and a burner for heating and an evaporator 2 for producing the gaseous mixture by primarily heating the mixture of the kerosene and water, and the reformer 3 is provided with a heat transfer means for secondarily heating the gaseous mixture. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reforming method and a device for steam reforming a difficult-to-vaporize liquid raw fuel such as kerosene or gasoline used in a fuel cell power generator or the like.
[0002]
[Prior art]
A fuel cell power generation device is a device that directly converts chemical energy of a fuel into electric energy without passing through mechanical energy or heat energy, and can realize high energy efficiency. As a well-known form of a fuel cell, a pair of electrodes are arranged with an electrolyte layer interposed therebetween, and a fuel gas containing hydrogen is supplied to one electrode (anode side) and oxygen gas 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]
The following shows an equation representing an electrochemical reaction occurring in a fuel cell. (1) shows the reaction on the anode side, (2) shows the reaction on the cathode side, and the reaction expressed by the formula (3) proceeds in the whole 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, polymer electrolyte fuel cells, phosphoric acid type fuel cells, molten carbonate type fuel cells, etc. are based on the properties of the electrolyte. It is possible to use an oxidizing gas or a carbon dioxide gas containing carbon dioxide. Therefore, these fuel cells usually use air as an oxidant gas, and use a hydrogen-rich gas generated by steam reforming of a hydrocarbon-based raw fuel gas such as natural gas or city gas 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. Generating gas. The following equation (4) shows the methane reforming reaction in the reformer.
[0006]
CH ₄ + H ₂ O → 3H ₂ + CO (+206.14 KJ / mol: endothermic reaction) (4)
As shown in the above equation (4), since the reforming reaction of methane is an endothermic reaction, after adding steam to methane, the particulate reforming catalyst is formed by the combustion exhaust gas obtained by burning the fuel off-gas from the fuel cell. By maintaining the temperature at 600 to 700 ° C., a hydrogen-rich reformed gas is generated.
[0007]
The reformed gas exiting the reformer is supplied to a carbon monoxide converter to reduce carbon monoxide in the reformed gas, where the carbon monoxide is reduced to 1% or less, and In the case of a fuel cell (PAFC), this gas can be introduced into the fuel cell to generate power. The following equation (5) shows the conversion reaction of carbon monoxide 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 conversion reaction of carbon monoxide is an exothermic reaction, so that cooling is required to maintain the conversion reaction temperature of 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., and if carbon monoxide is present in the reformed gas, it becomes a catalyst poison and deteriorates in performance. , It is necessary to further reduce the carbon monoxide, for which the reformed gas is fed to a carbon monoxide remover, where the carbon monoxide is reduced to below 10 ppm. The following equation (6) shows a 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 the formula (6), since the selective oxidation reaction of carbon monoxide is an exothermic reaction, cooling is required to maintain the temperature at the selective oxidation reaction temperature of 160 to 230 ° C.
[0011]
As described above, the polymer electrolyte fuel cell (PEFC) has a low reaction temperature, and therefore differs from the phosphoric acid fuel cell (PAFC) (reaction temperature of about 180 ° C.) in that the steam for reforming is generated by its calorific value. Since it cannot be generated, it must be generated in the reforming system equipment. The amount of heat for generating the steam is usually obtained by heat exchange with the flue gas after leaving the reformer.
[0012]
By the way, as the hydrocarbon-based raw fuel, liquid fuels such as butane, propane, naphtha, methanol and the like are used in addition to gaseous fuels such as the natural gas and city gas. Since these liquid fuels vaporize relatively easily, they are generally gasified and steam reformed.
[0013]
Patent Literature 1 discloses an example of a device for gasifying a liquid fuel containing 58% by weight of methanol and 42% by weight of water to perform steam reforming. This device employs a configuration in which the evaporator and the reformer for the liquid fuel are integrated, and the heat of the combustion exhaust gas from the burner is supplied to both the evaporator and the reformer.
[0014]
In addition, other than the above, a gas containing hydrogen produced by steam reforming a liquid raw fuel such as kerosene or gasoline has recently been used as a fuel gas because of its ease of transportation and low price. Methods are also being considered.
[0015]
[Patent Document 1]
JP-A-61-153957 (pages 2 to 5, FIGS. 1, 5, and 6)
[0016]
[Problems to be solved by the invention]
By the way, the above-mentioned liquid raw fuel such as kerosene and gasoline contains a component having a relatively high boiling point, and has a problem that it is difficult to vaporize as compared with the liquid fuel such as butane, propane, naphtha and methanol. For example, kerosene is a hydrocarbon-based fuel that is refined from petroleum and has a fraction of 150 ° C. to 270 ° C. and is liquid at room temperature.
[0017]
In order to reform kerosene with steam, after removing 80 wtppm or less of sulfur contained in kerosene in advance, the kerosene is mixed with water for reforming steam and heated to 270 ° C or more, preferably 300 ° C or more to vaporize. After that, or after mixing with steam heated to 350 ° C. or more and vaporizing using steam enthalpy, it is necessary to reform into hydrogen and carbon monoxide in a reformer.
[0018]
In addition, since the reforming reaction of kerosene is an endothermic reaction, the particulate reforming catalyst is maintained at 600 to 700 ° C. in the vicinity of the reformed gas outlet by the combustion exhaust gas obtained by burning the fuel off-gas from the fuel cell with the reformer burner. Thereby, the steam reforming reaction is continued. The temperature near the inlet of the raw reforming 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 which has been studied conventionally using kerosene of this kind 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, and then supplied to the vaporizer 2 as the reforming raw fuel. It is supplied to the reaction layer 3a. In the catalytic reaction layer 3a, after being converted into a hydrogen-rich reformed gas by a steam reforming reaction, the reformed gas is supplied to a carbon monoxide converter 4 to increase the hydrogen concentration by the carbon monoxide converting reaction. After being supplied to the carbon monoxide remover 5 together with the amount of air, the carbon monoxide is reduced to 10 ppm or less by the carbon monoxide selective oxidation reaction, and then supplied to the fuel cell 6.
[0020]
Meanwhile, in FIG. 3, a heat source 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 supplied by air from a combustion air blower 8. Since it is the combustion exhaust gas (the temperature is about 300 ° C.) after being burned and giving the combustion heat for the steam reaction of methane as an endothermic reaction, the temperature of the mixture of the reforming raw fuel is 250 ° C. at the maximum. The temperature can be raised only to the extent.
[0021]
When the raw fuel is a gas such as city gas, the temperature near the inlet of the city gas in the reforming catalyst layer is sufficient at this level, but the raw fuel is a non-vaporizable liquid raw fuel such as kerosene. In such a case, components having a high boiling point contained in kerosene are condensed and cover the catalyst surface, or the carbon component adheres to the reaction area, thereby adversely affecting the reforming reaction. It is necessary to raise the temperature of the mixture of steam to at least about 300 ° C. and then supply the mixture to the reformer. For this reason, 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 power generation efficiency is reduced by the amount of power consumed in the electric heater 9.
[0022]
The present invention has been made in order to solve the above problems, and an object of the present invention is to convert a mixture of a non-vaporizable liquid raw fuel such as kerosene and reforming steam at least without using an electric heater. It is an object of the present invention to provide a highly efficient and high-performance liquid fuel reforming method and apparatus capable of raising the temperature to about 300 ° C.
[0023]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a reforming method for steam-reforming a non-vaporizable liquid raw fuel such as kerosene or gasoline in a catalytic reaction layer of a reformer.
The mixture of the vaporizable liquid raw fuel and water is primarily heated by the combustion exhaust gas of the heating burner of the reformer to form a mixture, and the mixture is further mixed with at least the vaporizable liquid raw fuel. After secondary heating by heat transfer from the reformer to a predetermined temperature or higher for preventing the condensation of high boiling components contained in the reformer, the reformer is supplied to the catalytic reaction layer of the reformer to reform ( The invention of claim 1).
[0024]
As an embodiment of the first aspect of the invention, the following second aspect of the invention is preferable. That is, in the reforming method according to the first aspect, the raw material fuel that is difficult to vaporize is kerosene, and the predetermined temperature is 300 ° C.
[0025]
According to the above-described reforming method, the primary-heated air-fuel mixture can be heated to 300 ° C. or higher without using an electric heater, and a highly efficient and high-performance liquid fuel reforming method can be provided. In addition, as disclosed in Patent Document 1, a method of supplying the heat of the combustion exhaust gas of the burner to both the evaporator and the reformer and simultaneously achieving the primary heating and the secondary heating in the evaporator. Is also possible. However, in this case, since the heat of the combustion exhaust gas cannot be effectively used in a stepwise manner according to the temperature level, the overall thermal efficiency is reduced. Therefore, there is a difficulty as a method for reforming kerosene or the like, which is the object of the present invention.
[0026]
Further, as an apparatus for performing the reforming method, the invention of the following claim 3 is preferable. That is, it is a reformer for carrying out the reforming method according to claim 1 or 2, wherein the reformer having a catalytic reaction layer and a heating burner, and a combustion exhaust gas from the heating burner are used for gasification. And a vaporizer for generating a mixture by primary heating a mixture of the ionic liquid raw fuel and water, and further comprising a heat transfer means for secondary heating the mixture. The invention of claim 3).
[0027]
Further, as an embodiment of the invention of claim 3, the following inventions of claims 4 to 6 are preferable. That is, in the reformer according to the third aspect, the heat transfer means is a heat exchanger provided on a wall surface of the heating burner (the invention of the fourth aspect). Further, in the reformer according to claim 3, the heat transfer means is a heat exchanger provided in the reformed gas flow path in the catalytic reaction layer (the invention of claim 5). Furthermore, in the reformer according to claim 4 or 5, the heat exchanger includes a helical pipe through which the mixture or the reformed gas flows (the invention according to claim 6). .
[0028]
According to the configuration of the above embodiment, the amount of heat radiation from the surface of the reformer including the burner is reduced, and the effect of further improving the thermal efficiency is obtained.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0030]
FIG. 1 shows a schematic configuration of a fuel cell power generator including a kerosene reformer according to an embodiment of the present invention. Members having the same functions as those in FIG. 3 are denoted by the same reference numerals, and detailed description is omitted.
[0031]
In the embodiment shown in FIG. 1, a helical pipe 11 is wound around the wall of the reformer burner 7, and a mixture of kerosene and reforming steam flowing out of the vaporizer 2 is passed therethrough to perform secondary heating. Later, it is supplied to the reformer 3. In normal operation, the outer wall of the reformer burner is kept at about 500 ° C., and thus, according to the above configuration, the mixture of kerosene and reforming steam is heated to about 400 ° C. Since it is supplied to the reformer in a state, the unvaporized components do not condense and do not adversely affect the reforming performance, and the reforming reaction can be performed well. Further, according to such a configuration, an effect is obtained that the amount of heat radiated from the surface of the reformer burner is reduced and the thermal efficiency is improved.
[0032]
In FIG. 1, a configuration is shown in which a pipe is wound spirally around the wall surface of the reformer burner. However, the wall surface of the reformer burner is formed into a two-layer jacket shape, and kerosene and The same effect can be obtained by a configuration in which a mixture of reforming steam is passed.
[0033]
Next, the embodiment of FIG. 2 will be described. Members having the same functions as those in FIG. 3 are denoted by the same reference numerals, and detailed description is omitted.
[0034]
In the embodiment of FIG. 2, a helical pipe 12 is wound around the wall of the reformed gas flow path, and a mixture of kerosene and reforming steam flowing out of the vaporizer 2 flows through the spiral pipe 12 to the reformer. Supply. In normal operation, the reformed gas exits the reforming catalyst layer at about 600 to 700 ° C., is cooled while heating the reforming catalyst layer, and is discharged at about 350 ° C. Will be introduced.
[0035]
Therefore, since the wall surface of the gas inlet portion of the reformed gas flow path 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 supplied to the reformer in a completely gaseous state, the reforming reaction can be favorably performed as in the embodiment of FIG. Further, according to such a configuration, an effect is obtained that the amount of heat radiation from the surface of the reformer is reduced and the thermal efficiency is improved. In FIG. 2, a configuration in which a helical pipe is wound around the wall surface of the reformed gas flow channel is shown. However, the wall surface of the reformed gas flow channel is formed into a two-layer jacket, and between the inner and outer jackets, It is also possible to adopt a configuration in which a mixture of kerosene and reforming steam flows.
[0036]
【The invention's effect】
As described above, according to the present invention, in a reforming method for steam-reforming a non-vaporizable liquid raw fuel such as kerosene or gasoline in a catalytic reaction layer of a reformer, the non-vaporizable liquid raw fuel and water Is primarily heated by the combustion exhaust gas of the heating burner of the reformer to form an air-fuel mixture, and this air-fuel mixture is prevented from condensing at least the high-boiling components contained in the difficult-to-evaporate liquid raw fuel. To a predetermined temperature or more, after secondary heating by heat transfer from the reformer, to reform by supplying to the catalytic reaction layer of the reformer,
As a device for carrying out the method, a reformer having a catalytic reaction layer and a heating burner, and a mixture of a non-vaporizable liquid raw fuel and water are primarily heated by a combustion exhaust gas of the heating burner to form an air-fuel mixture. And further comprising a heat transfer means for secondary heating the air-fuel mixture,
A mixture of a non-vaporizable liquid raw fuel such as kerosene and a reforming vapor can be heated to at least about 300 ° C. without using an electric heater. A 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. 1 of the present invention. 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 (6)

In a reforming method of steam reforming a non-vaporizable liquid raw fuel such as kerosene or gasoline in a catalytic reaction layer of a reformer,
The mixture of the vaporizable liquid raw fuel and water is primarily heated by the combustion exhaust gas of the heating burner of the reformer to form a mixture, and the mixture is further mixed with at least the vaporizable liquid raw fuel. After secondary heating by heat transfer from the reformer to a predetermined temperature or higher to prevent condensation of high boiling components contained in, reforming by supplying to the catalytic reaction layer of the reformer A method for reforming a liquid fuel, comprising: 2. The method according to claim 1, wherein the raw material fuel is a kerosene, and the predetermined temperature is 300.degree. It is a reformer for implementing the reforming method according to claim 1 or 2, wherein the reformer having a catalytic reaction layer and a heating burner, and a combustion exhaust gas from the heating burner are used to form a non-vaporizable liquid. A vaporizer for primary heating a mixture of raw fuel and water to generate an air-fuel mixture, and the reformer further includes a heat transfer means for secondary heating the air-fuel mixture. Fuel reformer. 4. The reformer for liquid fuel according to claim 3, wherein the heat transfer means is a heat exchanger provided on a wall surface of a heating burner. 4. The liquid fuel reforming apparatus according to claim 3, wherein the heat transfer unit is a heat exchanger provided in the reformed gas flow path in the catalytic reaction layer. 5. The liquid reformer according to claim 4, wherein the heat exchanger includes a spiral pipe through which the mixture or the reformed gas flows.

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