JP2012142174A - Hydrogen manufacturing system for fuel cell, fuel cell system, deionization method of hydrocarbon-based fuel and hydrogen manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen manufacturing system for a fuel cell which is equipped with a low-cost deionization part capable of miniaturization, and to provide a fuel cell system, a deionization method of hydrocarbon-based fuel, and a hydrogen manufacturing method.SOLUTION: The hydrogen manufacturing system 20 for the fuel cell includes: a fuel supply part 2 by which the hydrocarbon-based fuel containing moisture having electric conductivity of 0.05 to 500 μS/cm and a sulfur compound is supplied to a later stage; a desulfurization part 3 having a desulfurization catalyst to desulfurize the hydrocarbon-based fuel; and a hydrogen generation part 4 which generates hydrogen from the hydrocarbon-based fuel, and also includes a deionization part 15 which is provided between the fuel supply part 2 and the desulfurization part 3 or the desulfurization part 3 and the hydrogen generation part 4, and brings the hydrocarbon-based fuel supplied from the fuel supply part 2 or the hydrocarbon-based fuel passing through the desulfurization part 3 into contact with a porous ion adsorbent.

Description

  The present invention relates to a fuel cell hydrogen production system, a fuel cell system, a hydrocarbon fuel deionization method, and a hydrogen production method.

  In general, as a fuel gas for a fuel cell, a gas containing hydrogen as a main component is used, and as a raw material, hydrocarbons such as natural gas, LPG, city gas, naphtha, and kerosene are used. Hydrogen obtained by subjecting these hydrocarbon-containing fuels to high-temperature treatment on a catalyst together with water vapor, partial oxidation with an oxygen-containing gas, or a self-heat recovery type reforming reaction in a system where water vapor and oxygen-containing gas coexist Is used as fuel hydrogen for fuel cells (see, for example, Patent Document 1 below).

  When city gas is used, gas is usually supplied to a fuel production apparatus provided in the fuel cell through an existing pipeline (see, for example, Patent Document 2 below).

JP 2008-115309 A Japanese Unexamined Patent Publication No. 6-44998

  By the way, a pipeline that supplies city gas or the like may be damaged by a crack or the like due to, for example, an earthquake or deterioration. In such a case, groundwater or the like may be mixed into the hydrocarbon fuel in the pipeline. When water containing mineral content such as groundwater is supplied to the fuel cell system, the mineral content poisons the reforming catalyst and the electrode catalyst, and the hydrogen production efficiency and the power generation efficiency of the fuel cell are reduced.

  As a method for removing ions such as minerals from the hydrocarbon fuel, use of an ion exchange resin is conceivable. However, these methods increase the running cost of the fuel cell system and increase the size of the apparatus.

  Therefore, the present invention provides a fuel cell hydrogen production system and fuel cell system including a deionization section that can be reduced in size at low cost, and a hydrocarbon fuel deionization method and hydrogen production method. Objective.

  In order to solve the above-mentioned problems, the present invention is a hydrogen production system for a fuel cell, which is a fuel for supplying a hydrocarbon fuel containing water and a sulfur compound having an electric conductivity of 0.05 to 500 μS / cm to the subsequent stage. A supply unit, a desulfurization unit having a desulfurization catalyst for desulfurizing hydrocarbon fuel, and a hydrogen generation unit for generating hydrogen from the hydrocarbon fuel, between the fuel supply unit and the desulfurization unit or between the desulfurization unit and hydrogen Hydrogen production system for a fuel cell comprising a deionization unit that is provided between the generation unit and that contacts a hydrocarbon fuel supplied from a fuel supply unit or a hydrocarbon fuel that has passed through a desulfurization unit and a porous ion adsorbent I will provide a.

  The electrical conductivity of moisture contained in the hydrocarbon fuel can be measured in accordance with JIS K0130: 2008 “General Rules for Electrical Conductivity Measurement”.

  According to the hydrogen production system of the present invention, the deionization section is provided between the fuel supply section and the desulfurization section or between the desulfurization section and the hydrogen generation section, thereby having the specific electrical conductivity. It is possible to efficiently remove ions in the water of the hydrocarbon fuel containing water. Thereby, although it is a compact apparatus, it can fully prevent that a reforming catalyst is poisoned by mixing of water containing minerals, such as groundwater, and it becomes possible to supply hydrogen stably at low cost. .

  The hydrogen production system of the present invention preferably includes the deionization unit between the fuel supply unit and the desulfurization unit.

  The porous ion adsorbent preferably contains zeolite in terms of deionization performance, long life, and low cost.

  In the fuel cell hydrogen production system of the present invention, it is preferable that the hydrocarbon-based fuel contains a hydrocarbon compound having 4 or less carbon atoms from the standpoint of fuel availability.

  The present invention also provides a fuel cell system comprising the hydrogen production system of the present invention.

  The present invention also provides a method for deionizing a hydrocarbon fuel, which comprises contacting a hydrocarbon fuel containing moisture having an electric conductivity of 0.05 to 500 μS / cm with a porous ion adsorbent.

  According to the hydrocarbon fuel deionization method of the present invention, ions in water can be efficiently removed. Thereby, it is a case where a hydrocarbon fuel contains the water | moisture content containing minerals, such as groundwater, Comprising: It can prevent that the reforming catalyst and electrode catalyst of a fuel cell system are poisoned.

  The porous ion adsorbent preferably contains zeolite in terms of deionization performance, long life, and low cost.

  In the hydrocarbon-based fuel deionization method of the present invention, it is preferable that the hydrocarbon-based fuel contains a hydrocarbon compound having 4 or less carbon atoms from the viewpoint of easy availability of the fuel.

  The present invention also provides a hydrogen production method in which hydrogen is obtained by reforming a hydrocarbon fuel deionized by the deionization method of the present invention.

  When the hydrocarbon fuel contains a sulfur compound, the deionized hydrocarbon fuel can be desulfurized and reformed to obtain hydrogen.

  According to the present invention, it is possible to provide a fuel cell hydrogen production system and a fuel cell system including a deionization section that can be reduced in size at low cost, and a hydrocarbon fuel deionization method and hydrogen production method. it can.

It is a conceptual diagram which shows an example of the fuel cell system which concerns on embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a conceptual diagram showing an example of a fuel cell system according to an embodiment of the present invention. The fuel cell system 1 includes a fuel supply unit 2, a deionization unit 15, a desulfurization unit 3, a hydrogen generation unit 4, a cell stack 5, an offgas combustion unit 6, a water supply unit 7, and a water vaporization unit 8. And an oxidant supply unit 9, a power conditioner 10, and a control unit 11, and each unit is connected by piping (not shown) in the flow shown in FIG.

  The fuel supply unit 2 supplies hydrocarbon fuel to the deionization unit 15. The supplied hydrocarbon fuel contains water having an electric conductivity of 0.05 to 500 μS / cm. Here, as the hydrocarbon-based fuel, a compound containing carbon and hydrogen (may contain other elements such as oxygen) in the molecule or a mixture thereof is used. Examples of hydrocarbon fuels include hydrocarbons, alcohols, ethers, and biofuels. These hydrocarbon fuels are derived from conventional fossil fuels such as petroleum and coal, and synthesized from syngas. A fuel-derived one or a biomass-derived one can be used as appropriate. Specific examples of hydrocarbons include methane, ethane, propane, butane, natural gas, LPG (liquefied petroleum gas), city gas, town gas, gasoline, naphtha, kerosene, and light oil. Examples of alcohols include methanol and ethanol. Examples of ethers include dimethyl ether. Biofuels include biogas, bioethanol, biodiesel, and biojet. In the present embodiment, a gas containing methane as a main component (for example, city gas, town gas, natural gas, biogas, etc.) or LPG supplied through a pipeline is suitable. Can be used for

  The electrical conductivity of moisture in the hydrocarbon fuel is 0.05 to 500 μS / cm. Examples of moisture ions include magnesium ions, calcium ions, vanadium ions, potassium ions, sodium ions, iron ions, and copper ions.

  In the present embodiment, the hydrocarbon fuel preferably contains a hydrocarbon compound having 4 or less carbon atoms. Specific examples of the hydrocarbon compound having 4 or less carbon atoms include saturated aliphatic hydrocarbons such as methane, ethane, propane, and butane, and unsaturated aliphatic hydrocarbons such as ethylene, propylene, and butene. The hydrocarbon-based fuel is preferably a gas containing a hydrocarbon compound having 4 or less carbon atoms, that is, a gas containing one or more of methane, ethane, ethylene, propane, propylene, butane and butene. Moreover, as gas containing a C4 or less hydrocarbon compound, the gas containing 80 volume% or more of methane is preferable, and the gas containing 85 volume% or more of methane is more preferable.

The hydrocarbon fuel generally contains a sulfur compound. Examples of the sulfur compound include a sulfur compound originally mixed in hydrocarbons and the like and a compound contained in an odorant for detecting gas leakage. Examples of sulfur compounds originally mixed in hydrocarbons include hydrogen sulfide (H ₂ S), carbonyl sulfide (COS), carbon disulfide (CS ₂ ), and the like. As the odorant, alkyl sulfide, mercaptan alone or a mixture thereof is used. For example, diethyl sulfide (DES), dimethyl sulfide (DMS), ethyl methyl sulfide (EMS), tetrahydrothiophene (THT), tert-butyl mercaptan ( TBM), isopropyl mercaptan, dimethyl disulfide (DMDS), diethyl disulfide (DEDS) and the like are used. The sulfur compound is contained in an amount of about 0.1 to 10 mass ppm in terms of sulfur atom based on the total amount of hydrocarbon fuel.

  The hydrocarbon-based fuel may contain components other than the water and sulfur compounds as long as they do not adversely affect the characteristics of the fuel cell system.

  The hydrocarbon-based fuel supplied from the fuel supply unit 2 is supplied to the deionization unit 15. The deionization part 15 has a porous ion adsorbent, and the porous ion adsorbent adsorbs moisture-derived ions contained in the hydrocarbon fuel. Here, 0-100 degreeC is preferable, as for the temperature of a deionization part, 0-70 degreeC is more preferable, and 0-30 degreeC is further more preferable. The temperature of the deionization part is particularly preferably room temperature. As the porous ion adsorbent, it is preferable to include zeolite, styrene-based cation exchange resin, etc. Among them, it is preferable to include zeolite having excellent adsorptivity.

  Examples of the zeolite include A type zeolite, ZSM-5 type zeolite, mordenite type zeolite, X type zeolite, Y type zeolite, VPI-5, MCM-41 and the like. These zeolites preferably do not contain metals.

  The styrene cation exchange resin is not particularly limited as long as it can capture ions derived from moisture contained in the hydrocarbon fuel, but various commercially available ion exchange resins can be used. The amount of each zeolite or styrene-based cation exchange resin used can be appropriately set according to the type and concentration of water-derived ions contained in the hydrocarbon fuel.

  The hydrocarbon-based fuel from which moisture-derived ions have been removed in the deionization unit 15 is desulfurized in the desulfurization unit 3. The sulfur compound contained in the hydrocarbon-based fuel is removed by the desulfurization catalyst in the desulfurization unit 3 in order to poison the reforming catalyst in the hydrogen generation unit 4 and the electrode catalyst in the cell stack 5. As the desulfurization catalyst, a commonly used desulfurization catalyst can be used, and it is preferable to use a desulfurization catalyst containing a zeolite carrying a metal such as Ag, Cu or Zn, or a desulfurization catalyst containing an active metal such as Ni, Zn or Cu. When the desulfurization part 3 has Ag / X-type zeolite, it is preferable to contact the hydrocarbon fuel ion-removed in the deionization part 15 and the Ag / X-type zeolite at a temperature of 65 to 105 ° C. Moreover, when the desulfurization part 3 has a desulfurization catalyst containing active metals, such as Ni, Zn, or Cu, the hydrocarbon-type fuel ion-removed by the deionization part 15 and a desulfurization catalyst are 200-300 degreeC conditions. It is preferable to contact with. Desulfurization under such temperature conditions can be performed by, for example, the desulfurization unit 3 having a heating unit.

  The hydrocarbon fuel desulfurized by the desulfurization unit 3 is supplied to the hydrogen generation unit 4. The hydrogen generation unit 4 constitutes a hydrogen production system 20 together with the fuel supply unit 2, the deionization unit 15, and the desulfurization unit 3. The hydrogen generator 4 includes a reformer that reforms the hydrocarbon fuel after deionization and desulfurization using a reforming catalyst, and generates a hydrogen-rich gas. The reforming method in the hydrogen generating unit 4 is not particularly limited, and for example, steam reforming, partial oxidation reforming, autothermal reforming, and other reforming methods can be employed. The reforming temperature is usually 200 to 800 ° C, preferably 300 to 700 ° C. The hydrogen generator 4 may have a configuration for adjusting the properties in addition to the reformer reformed by the reforming catalyst depending on the properties of the hydrogen rich gas required by the cell stack 5. For example, when the type of the cell stack 5 is a polymer electrolyte fuel cell (PEFC) or a phosphoric acid fuel cell (PAFC), the hydrogen generation unit 4 is configured to remove carbon monoxide in the hydrogen-rich gas. (For example, a shift reaction part and a selective oxidation reaction part). The hydrogen generation unit 4 supplies a hydrogen rich gas to the anode 12 of the cell stack 5.

  The reforming catalyst is not particularly limited, and a general reforming catalyst can be used. For example, a reforming catalyst in which a porous inorganic oxide selected from alumina, silica and the like is loaded with a metal selected from Group VIII metals such as nickel, cobalt, iron, ruthenium, rhodium, iridium and platinum is listed. be able to.

  Moreover, in the hydrogen generation part 4, it is preferable that water vapor | steam is supplied from the water vaporization part 8 in order to modify | reform hydrocarbon fuel. The water vapor is preferably generated by heating the water supplied from the water supply unit 7 in the water vaporization unit 8 and vaporizing it. Heating of the water in the water vaporization unit 8 may use heat generated in the fuel cell system 1 such as recovering heat of the hydrogen generation unit 4, heat of the off-gas combustion unit 6, or exhaust gas. Moreover, you may heat water using other heat sources, such as a heater and a burner separately. In FIG. 1, only heat supplied from the off-gas combustion unit 6 to the hydrogen generation unit 4 is described as an example, but the present invention is not limited to this.

  The fuel cell system 1 is supplied with hydrogen-rich gas from the hydrogen production system 20 through a pipe (not shown) connecting the hydrogen production system 20 and the cell stack 5. Electric power is generated in the cell stack 5 using this hydrogen-rich gas and an oxidizing agent. The type of the cell stack 5 in the fuel cell system 1 is not particularly limited, and examples thereof include a polymer electrolyte fuel cell (PEFC), a solid oxide fuel cell (SOFC), and phosphoric acid. A fuel cell fuel cell (PAFC), a molten carbonate fuel cell (MCFC), and other types can be employed. It should be noted that the components shown in FIG. 1 may be omitted as appropriate according to the type of cell stack 5, the reforming method, and the like.

  The oxidant is supplied from the oxidant supply unit 9 through a pipe connecting the oxidant supply unit 9 and the fuel cell system 1. As the oxidizing agent, for example, air, pure oxygen gas (which may contain impurities that are difficult to remove by a normal removal method), or oxygen-enriched air is used.

  The cell stack 5 generates power using the hydrogen rich gas from the hydrogen generation unit 4 and the oxidant from the oxidant supply unit 9. The cell stack 5 includes an anode 12 to which a hydrogen-rich gas is supplied, a cathode 13 to which an oxidant is supplied, and an electrolyte 14 disposed between the anode 12 and the cathode 13. The cell stack 5 supplies power to the outside via the power conditioner 10. The cell stack 5 supplies the hydrogen rich gas and the oxidant, which have not been used for power generation, to the off gas combustion unit 6 as off gas. Note that a combustion section (for example, a combustor that heats the reformer) provided in the hydrogen generation section 4 may be shared with the off-gas combustion section 6.

  The off gas combustion unit 6 burns off gas supplied from the cell stack 5. The heat generated by the off-gas combustion unit 6 is supplied to the hydrogen generation unit 4 and used for generation of a hydrogen rich gas in the hydrogen generation unit 4. The fuel supply unit 2, the water supply unit 7, and the oxidant supply unit 9 are configured by, for example, a pump and are driven based on a control signal from the control unit 11.

  The power conditioner 10 adjusts the power from the cell stack 5 according to the external power usage state. For example, the power conditioner 10 performs a process of converting a voltage and a process of converting DC power into AC power.

  The control unit 11 performs control processing for the entire fuel cell system 1. The control unit 11 includes, for example, a device including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface. The control unit 11 is electrically connected to the fuel supply unit 2, the water supply unit 7, the oxidant supply unit 9, the power conditioner 10, and other sensors and auxiliary equipment not shown. The control unit 11 acquires various signals generated in the fuel cell system 1 and outputs a control signal to each device in the fuel cell system 1.

  As described above, according to the hydrogen production system and the fuel cell system of the present invention, hydrogen can be stably supplied and power can be generated even when a hydrocarbon fuel containing water containing minerals such as groundwater is used. In addition, the hydrogen production system and the fuel cell system of the present invention can have the above-described deionization function, but the size of the apparatus and the increase in running cost can be sufficiently suppressed.

  Next, the deionization method for hydrocarbon fuel and the method for producing hydrogen of the present invention will be described. In the method for deionizing a hydrocarbon fuel of the present invention, a hydrocarbon fuel containing water having an electric conductivity of 0.05 to 500 μS / cm is brought into contact with a porous ion adsorbent.

  Examples of the hydrocarbon fuel containing water having an electric conductivity of 0.05 to 500 μS / cm include the hydrocarbon fuels described above.

  Specific examples of the means for bringing the hydrocarbon fuel into contact with the porous ion adsorbent include the fuel supply unit 2, the deionization unit 15, and the desulfurization unit 3 described above. That is, hydrocarbon fuel is supplied to the deionization unit 15 by the fuel supply unit 2, and ions derived from moisture contained in the hydrocarbon fuel are adsorbed and removed by the porous ion adsorbent. Thereafter, the hydrocarbon-based fuel from which ions are removed is supplied to the desulfurization unit 3, and the supplied hydrocarbon-based fuel is brought into contact with the desulfurization catalyst in the desulfurization unit 3 for desulfurization.

  In the method for producing hydrogen according to the present invention, the hydrocarbon fuel deionized by the deionization method is reformed to generate hydrogen (hydrogen-rich gas). The reforming method is not particularly limited as described above, and for example, steam reforming, partial oxidation reforming, autothermal reforming, and other reforming methods can be employed. The reforming temperature is usually 200 to 800 ° C, preferably 300 to 700 ° C.

  As described above, a general reforming catalyst can be used as the reforming catalyst. For example, nickel, cobalt, iron, ruthenium, rhodium, iridium, a porous inorganic oxide selected from alumina, silica and the like can be used. A reforming catalyst supporting a metal selected from Group VIII metals of the periodic table such as platinum is preferable.

  In reforming, since steam is required to reform the fuel, it is preferable that the steam is supplied from the water vaporization unit 8 to the hydrogen generation unit 4. The water vapor is preferably generated by heating the water supplied from the water supply unit 7 in the water vaporization unit 8 and vaporizing it.

  In addition, the above description is description about one Embodiment of this invention, and does not limit this invention. For example, the deionization unit 15 may be provided between the desulfurization unit 3 and the hydrogen generation unit 4. In this case, sulfur poisoning of the deionized part can be avoided.

  This embodiment is preferable in reducing the size of the apparatus.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Fuel supply part, 3 ... Desulfurization part, 4 ... Hydrogen generation part, 5 ... Cell stack, 15 ... Deionization part, 20 ... Hydrogen production system.

Claims (10)

A hydrogen production system for a fuel cell,
A fuel supply unit for supplying a hydrocarbon fuel containing water and a sulfur compound having an electric conductivity of 0.05 to 500 μS / cm to the subsequent stage;
A desulfurization section having a desulfurization catalyst for desulfurizing hydrocarbon fuel,
A hydrogen generation part for generating hydrogen from a hydrocarbon-based fuel,
Provided between the fuel supply unit and the desulfurization unit or between the desulfurization unit and the hydrogen generation unit, the hydrocarbon fuel supplied from the fuel supply unit or the hydrocarbon system via the desulfurization unit A hydrogen production system for a fuel cell, comprising: a deionization unit that brings a fuel into contact with a porous ion adsorbent.   The hydrogen production system for a fuel cell according to claim 1, comprising the deionization unit between the fuel supply unit and the desulfurization unit.   The hydrogen production system for a fuel cell according to claim 1 or 2, wherein the porous ion adsorbent contains zeolite.   The hydrogen production system for a fuel cell according to any one of claims 1 to 3, wherein the hydrocarbon fuel includes a hydrocarbon compound having 4 or less carbon atoms.   A fuel cell system comprising the hydrogen production system according to any one of claims 1 to 4.   A method for deionizing a hydrocarbon fuel, comprising contacting a hydrocarbon fuel containing water having an electric conductivity of 0.05 to 500 μS / cm with a porous ion adsorbent.   The hydrocarbon fuel deionization method according to claim 6, wherein the porous ion adsorbent contains zeolite.   The hydrocarbon fuel deionization method according to claim 6 or 7, wherein the hydrocarbon fuel contains a hydrocarbon compound having 4 or less carbon atoms.   A method for producing hydrogen, comprising reforming the hydrocarbon-based fuel deionized by the deionization method according to any one of claims 6 to 8 to obtain hydrogen.   The method for producing hydrogen according to claim 9, wherein the hydrocarbon fuel contains a sulfur compound, and the deionized hydrocarbon fuel is desulfurized and reformed to obtain hydrogen.

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