JP4945158B2 - Fuel cell power generation system - Google Patents

Description

  The present invention relates to a fuel cell power generation system that generates power by electrochemically reacting hydrogen and oxygen, and in particular, it is easy to recover carbon dioxide, which is a global warming gas generated in the process of generating hydrogen necessary for power generation. The present invention relates to a fuel cell power generation system that is capable of high-efficiency power generation and is environmentally friendly.

  In recent years, there has been a fuel cell power generation system that generates hydrogen from a hydrocarbon-based fuel, supplies the generated hydrogen and air to a fuel cell stack, and generates power by a fuel cell reaction between hydrogen and oxygen in the air. ,Attention has been paid. Such a fuel cell power generation system is disclosed in, for example, Japanese Patent Laid-Open No. 2002-372199 (Patent Document 1).

FIG. 5 shows an example of the configuration of a conventional fuel cell power generation system that generates power by supplying hydrogen generated from fuel to a fuel cell stack. In the fuel cell power generation system shown in FIG. 5, three sets of polymer electrolyte fuel cell stacks are used as the fuel cell stack. This fuel cell power generation system is supplied with hydrocarbons (natural gas 1 in the illustrated example) and steam (H ₂ O) 155, and generates three parts of hydrogen 58 by steam reforming reaction of hydrocarbons. It is roughly divided into fuel cell portions including solid polymer fuel cell stacks 9, 95, and 108.

  First, the part which produces | generates hydrogen by steam reforming reaction is demonstrated.

  The part that generates hydrogen includes, as main components, a desulfurizer 2, a reformer 3, a CO shift converter 4, a hydrogen separator 53, a condenser 55, flow control valves 27, 33, 162, 164, 167, and 171. 174, an air supply blower 12, a reformer burner 156, a vaporizer 157, a vaporizer pump 158, a water tank 159, a makeup water pump 161, and a vaporizer burner 170.

  Natural gas 1 as fuel is supplied to the desulfurizer 2 via the flow control valve 27, supplied to the reformer burner 156 via the flow control valve 164, and supplied to the vaporizer burner 170 via the flow control valve 171. Supplied. The vaporizer burner 170 is for heating the vaporizer 157 for generating water vapor necessary for the steam reforming reaction from water. In addition to the natural gas 1, the air 14 from the air supply blower 12 controls the flow rate. Supplied through a valve 167 and exhausts combustion exhaust gas 175. The reformer burner 156 is for heating the reformer 3 for performing the steam reforming reaction. In addition to the natural gas 1, the air 14 from the air supply blower 12 passes through the flow control valve 164. The combustion exhaust gas 166 is exhausted with combustion. Since this combustion exhaust gas 166 has a high temperature, it is sent to the vaporizer 157 for use as a heat source for vaporizing water vapor in the vaporizer 157, and is discharged from the vaporizer 157 as an exhaust gas 176. Yes. Water 173 is supplied to the vaporizer 157 from the water tank 159 via the vaporizer pump 158. The water 173 is vaporized in the vaporizer 157 and discharged from the vaporizer 157 as water vapor 155. The water tank 159 is supplied with makeup water 160 via a makeup water pump 161.

  In addition to the natural gas 1, a desulfurizer recycle gas 32 that is recycled from the CO shift converter outlet gas 21 is supplied to the desulfurizer 2 via a flow control valve 33. The desulfurized natural gas from the desulfurizer 2, that is, the desulfurized natural gas 24, is mixed with the steam 155 supplied from the vaporizer 157 via the flow control valve 174 and supplied to the reformer 3 as a mixed gas 154. It has come to be. In the reformer 3, a steam reforming reaction of a hydrocarbon such as methane described later occurs. The outlet gas from the reformer 50 (ie, the hydrogen-rich reformed gas 22) is then supplied to the CO shift converter 4. The CO shift converter outlet gas 21 is a reformed gas whose carbon monoxide concentration is reduced to 1% by volume or less. As described above, a part of the gas is recycled to the desulfurizer 2 as the desulfurizer recycle gas 32. The hydrogen separator supply gas 52 is supplied to the hydrogen separator 53. “Hydrogen-rich” means containing hydrogen at a concentration sufficient to contribute to power generation by the fuel cell reaction.

  The hydrogen separator 53 separates the hydrogen 58 from the hydrogen separator supply gas 52, and the remaining gas from which the hydrogen 58 has been separated, that is, the hydrogen separator exhaust gas 54, is supplied to a condenser (condenser) 55. . The water condensed in the condenser 53 (condensed water 57) is recycled to the water tank 159. The hydrogen separator exhaust gas 54 from which water has been condensed and removed by the condenser 53 is discharged from the condenser 55 as a hydrogen separator dry exhaust gas 56.

  Next, the fuel cell portion including the polymer electrolyte fuel cell stack 9, 95, 108 will be described.

  The polymer electrolyte fuel cell stack 9 includes a fuel electrode 6 to which hydrogen 58 is supplied via a flow control valve 86, and an air electrode 8 to which air 25 is supplied from an air supply blower 115 via a flow control valve 10. And a solid polymer electrolyte 7 sandwiched between the fuel electrode 6 and the air electrode 8. Along with the fuel cell reaction, the air electrode 8 discharges the air electrode exhaust gas 13 and the produced water 30 from the air electrode 8. The fuel electrode 6 is provided with a purge valve 60 for purging the gas in the fuel electrode 6 as the purge gas 61. The DC power (fuel cell DC output 18) generated in such a polymer electrolyte fuel cell stack 9 is supplied to the output adjusting device 16 and converted to AC power, and supplied to the load 17 as the AC power output 19 at the transmission end. It has become so.

  Similarly, the polymer electrolyte fuel cell stacks 95 and 108 include fuel electrodes 92 and 105 to which hydrogen 58 is supplied via flow control valves 87 and 88, solid polymer electrolytes 93 and 106, and air, respectively. Air electrodes 94 and 107 to which air 91 and 104 are supplied from supply blowers 89 and 102 through flow control valves 90 and 103 are provided. Purge valves 119 and 122 for discharging purge gases 120 and 123 are attached to the fuel electrodes 92 and 105. From the air electrodes 94 and 107, the air electrode exhaust gas 100 and 113 and the generated water 116 and 117 are discharged. Fuel cell DC outputs 98 and 111 from the polymer electrolyte fuel cell stacks 95 and 108 are sent to the output adjusting devices 96 and 109 to be converted into AC power, and loads 97 and 110 are used as power transmission end AC outputs 99 and 112, respectively. To be supplied.

  In FIG. 5, each of the polymer electrolyte fuel cell stacks 9, 95, 108 has a set of fuel electrodes 6, 92, 105, solid polymer electrolytes 7, 93, 106 and air electrodes 8, 94. , 107, the solid polymer fuel cell stacks 9, 95, and 108 are actually combined with a plurality of single cells in a predetermined manner. A direct current and a direct voltage can be output.

  Next, the operation of the conventional fuel cell power generation system shown in FIG. 5 will be described.

  The natural gas 1 of the fuel is supplied to the desulfurizer 2, the vaporizer burner 170, and the reformer burner 156. The natural gas supplied to the desulfurizer 2 is for generating hydrogen 58 used for power generation in the polymer electrolyte fuel cell stacks 9, 95, 108, and the supply amount thereof is solid polymer type. Pre-setting between the sum of the battery currents of the fuel cell DC outputs 18, 98, 111 of the fuel cell stacks 9, 95, 108 and the opening of the flow control valve 27 (that is, the amount of natural gas supplied to the desulfurizer 2) By controlling the opening degree of the flow rate control valve 27 based on the relationship, the value is set in accordance with the sum of the battery currents of the fuel cell DC outputs 18, 98, and 111.

  The natural gas 1 contains a odorant such as mercaptan, and this odorant is the reforming catalyst filled in the reformer 3 or the fuel electrode of the polymer electrolyte fuel cell stack 9, 95, 108. It contains a sulfur component that causes deterioration of the electrode catalyst of 6,92,105. Therefore, first, the natural gas 1 is supplied to the desulfurizer 2. In the desulfurizer 2, the sulfur component in the natural gas 1 is adsorbed and removed by hydrodesulfurization by the action of the cobalt-molybdenum-based catalyst and the zinc oxide adsorbent of the filled desulfurization catalyst. That is, with a cobalt-molybdenum-based catalyst, sulfur and hydrogen are first reacted to generate hydrogen sulfide, and then hydrogen sulfide and zinc oxide are reacted to generate zinc sulfide, thereby removing the sulfur component. In order to supply hydrogen necessary for the generation of hydrogen sulfide, a part of the CO shift converter outlet gas 21, which is a hydrogen-rich reformed gas whose carbon monoxide concentration is reduced to 1% or less, is removed from the desulfurizer recycle gas 32. As a desulfurizer 2. The supply amount of the desulfurizer recycle gas 32 includes the opening degree of the flow control valve 27 (that is, the supply amount of natural gas for power generation) and the opening degree of the flow control valve 33 (that is, the supply amount of the desulfurizer recycle gas 32). By controlling the opening degree of the flow rate control valve 33 based on a preset relationship between the values, the value is set to a value commensurate with the supply amount of the natural gas for power generation. The hydrogen sulfide formation reaction and the zinc sulfide formation reaction are endothermic reactions, and the reaction heat necessary for these reactions is the heat generated by the aqueous shift reaction in the CO shift converter 4 which is an exothermic reaction described later. 4 is supplied to the desulfurizer 2.

  The natural gas desulfurized by the desulfurizer 2, that is, the desulfurized natural gas 24, is mixed with the water vapor 155 supplied from the vaporizer 157, and as a mixed gas 154 of the water vapor 155 and the desulfurized natural gas 24, a nickel catalyst or ruthenium It is supplied to a reformer 3 filled with a system catalyst as a reforming catalyst. The supply amount of the steam 155 mixed with the desulfurized natural gas 24 includes the opening degree of the flow control valve 27 (that is, the supply amount of natural gas for power generation) and the opening degree of the flow control valve 174 (that is, the supply amount of steam 155). The steam carbon ratio (molar ratio of water vapor to carbon) of the mixed gas 154 becomes a preset value by controlling the opening degree of the flow control valve 174 based on the preset relationship between To be set.

In the vaporizer 157, the water 173 supplied from the water tank 159 by the vaporizer pump 158 is vaporized. The heat necessary for vaporizing the water 173 is supplied by supplying the high-temperature combustion exhaust gas 166 from the reformer burner 156 to the vaporizer 157 and exchanging heat with the water 173. The combustion exhaust gas 166 that has exchanged heat with the water 173 in the vaporizer 157 is discharged from the vaporizer 157 as the exhaust gas 176. When supply of heat necessary for vaporization of the water 173 in the vaporizer 157 is insufficient only by heat exchange with the combustion exhaust gas 166 of the reformer burner 156, the natural gas 1 is supplied to the vaporizer burner 170. At the same time, air 172 which is a part of the air 14 taken in by the air supply blower 12 is supplied to the vaporizer burner 170, and both are combusted, whereby further heat is supplied to the vaporizer 157. A combustion exhaust gas 175 is discharged from the vaporizer burner 170.
The supply amount of the natural gas supplied to the vaporizer burner 170 is set in advance between the temperature of the vaporizer 157 and the opening of the flow control valve 171 (that is, the supply amount of natural gas for the vaporizer burner). Based on the relationship, the opening degree of the flow rate control valve 171 is controlled to set a predetermined vaporizer temperature. Further, the supply amount of the air 172 supplied to the vaporizer burner 170 includes the opening degree of the flow control valve 171 (that is, the supply amount of natural gas 168 to the vaporizer burner 170) and the opening degree of the flow control valve 167 (ie, the supply amount). And a predetermined air / fuel ratio (air-to-fuel) that is set in advance by controlling the opening degree of the flow rate control valve 167 based on a preset relationship with the supply amount of air 172 from the carburetor burner 170. Ratio).

  Condensed water 57 condensed by the condenser 55 is supplied to the water tank 159. If the water in the water tank 159 is insufficient by this alone, the makeup water pump 161 is operated as necessary to supply the makeup water 160 to the water tank 159.

  In the reformer 3, the steam reforming reaction of hydrocarbons contained in natural gas is performed by the action of the filled reforming catalyst, and the hydrogen-rich reformed gas 22 is produced. The steam reforming reaction of methane, which is the main component of natural gas 1, is expressed by equation (1).

(Methane steam reforming reaction)
CH ₄ + H ₂ O → CO + 3H ₂ (1)
The hydrocarbon steam reforming reaction such as the steam reforming reaction of methane shown in the formula (1) is generally an endothermic reaction, and is necessary from the outside of the reformer 3 in order to efficiently generate hydrogen. Heat must be supplied and the temperature of the reformer 3 maintained at 700-750 ° C. Therefore, the natural gas 1 is supplied to the reformer burner 156 as fuel, and the air 165 is supplied to the reformer burner 156, and both are combusted to reform the reaction heat necessary for the steam reforming reaction. Supply to vessel 3. The supply amount of the natural gas to the reformer burner 156 includes a preset opening degree of the flow control valve 27 (that is, supply amount of natural gas for power generation) and an opening degree of the flow control valve 162 (that is, reforming). By controlling the opening degree of the flow rate control valve 162 based on a preset relationship with the supply amount of the natural gas to the generator burner 156, a value corresponding to the supply amount of the natural gas for power generation is obtained. Set. Further, the supply amount of the air 165 to the reformer burner 156 includes the opening degree of the flow control valve 162 (that is, the supply amount of natural gas to the reformer burner 156) and the opening degree of the flow control valve 164 (that is, The amount of air 165 supplied to the reformer burner 156 is controlled based on a preset relationship with the reformer burner 156 so that the predetermined air-fuel ratio is set in advance by controlling the opening degree of the flow control valve 164. Set to

  The hydrogen-rich reformed gas 22, which is the exhaust gas of the reformer 3, is a cause of deterioration of the electrode catalyst of the fuel electrodes 6, 92, and 105 of the polymer electrolyte fuel cell stack 9, 95, and 108. Since carbon oxide is contained, the hydrogen-rich reformed gas 22 is supplied to the CO shift converter 4 filled with a shift catalyst such as a copper-zinc catalyst. By performing the aqueous shift reaction shown in the formula (2) by the action of the shift catalyst, the carbon monoxide concentration in the hydrogen-rich reformed gas 22 is reduced to 1% or less.

(Water-based shift reaction)
CO + H ₂ O → CO ₂ + H ₂ (2)
Since the aqueous shift reaction is an exothermic reaction, the generated heat is supplied to the desulfurizer 2, and as described above, the reaction for generating hydrogen sulfide and the reaction for generating zinc sulfide in the desulfurizer 2 which is an endothermic reaction. Use as heat.

  A part of the CO shift converter outlet gas 21 which is a reformed gas whose carbon monoxide concentration is reduced to 1% volume or less is supplied to the desulfurizer 2 as the desulfurizer recycle gas 32 as described above, and the rest is hydrogen The separator supply gas 52 is supplied to a hydrogen separator 53 having a hydrogen separation membrane such as a palladium membrane. In the hydrogen separator 53, hydrogen 58 is separated from the hydrogen separator supply gas 52. At that time, in order to perform efficient hydrogen separation, the hydrogen separator supply gas 52 is pressurized as necessary. The hydrogen separator exhaust gas 54 is discharged as a hydrogen separator dry exhaust gas 56 after condensing condensed water 57 with a condenser 55. The hydrogen 58 separated by the hydrogen separator 53 is supplied to the fuel electrode 6 of the polymer electrolyte fuel cell stack 9 through the flow control valve 86, and the polymer electrolyte fuel cell stack through the flow control valve 87. 95 is supplied to the fuel electrode 92 of the polymer electrolyte fuel cell stack 108 through the flow control valve 88.

  The amount of hydrogen 58 supplied to the fuel electrode 6 of the polymer electrolyte fuel cell stack 9 is determined by the battery current at the fuel cell DC output 18 and the opening of the flow control valve 86 (that is, the amount of hydrogen 58 to the fuel electrode 6). By controlling the opening degree of the flow control valve 86 based on a preset relationship with the supply amount), a value corresponding to the battery current of the fuel cell DC output 18 is set. The air 25 taken in by the air supply blower 115 is supplied to the air electrode 8 of the polymer electrolyte fuel cell stack 9. The supply amount of the air 25 is the battery current and flow rate of the fuel cell DC output 18. By controlling the opening degree of the flow control valve 10 based on a preset relationship with the opening degree of the control valve 10 (that is, the supply amount of the air 25 to the air electrode 8), the fuel cell DC output It is set to a value commensurate with 18 battery currents. The power generation temperature of the polymer electrolyte fuel cell stack 9 is generally 60 to 80 ° C., and this power generation temperature is maintained by heat generated by the battery reaction.

  Although not shown in FIG. 5, in order to maintain the power generation temperature of the polymer electrolyte fuel cell stack 9 at 60 to 80 ° C., the polymer electrolyte fuel cell stack 9 is cooled with cooling water. It is possible to use hot water obtained in this cooling process for hot water supply.

In the fuel electrode 6 of the polymer electrolyte fuel cell stack 9, about 80% of hydrogen (H ₂ ) is converted into proton (H ⁺ ) by the fuel electrode reaction shown in the formula (3) by the action of the platinum-based electrode catalyst. changes to ^- electronic (e).

(Fuel electrode reaction)
_{^{H 2 → 2H + + 2e -}} (3)
Protons generated at the fuel electrode 6 move inside the solid polymer electrolyte 7 and reach the air electrode 8. The solid polymer electrolyte 7 is made of, for example, a fluorine-based polymer having a sulfonic acid group. As an example of such a solid polymer electrolyte 7, there is a product called “Nafion”. On the other hand, the electrons generated at the fuel electrode 6 travel through the external circuit and reach the air electrode 8. Electric energy can be taken out as the fuel cell DC output 18 in the process of the electrons moving through the external circuit.

In the air electrode 8 of the solid polymer fuel cell stack 9, protons that have moved from the fuel electrode 6 to the air electrode 8 by the action of the platinum-based electrode catalyst, and an external circuit from the fuel electrode 6. Electron that has moved to the air electrode 8 and oxygen (O ₂ ) in the air 25 supplied to the air electrode 8 react by the air electrode reaction shown in the formula (4) to produce water (H ₂ O). To do. This water is discharged to the outside as produced water 30 by the battery reaction.

(Air electrode reaction)
2H ⁺ + (1/2) O ₂ + 2e ⁻ → H ₂ O (4)
Summarizing the equations (3) and (4), the battery reaction of the polymer electrolyte fuel cell stack 9 is expressed as the reverse reaction of water electrolysis, which is water generated from hydrogen and oxygen shown in equation (5). be able to.

(Battery reaction)
H ₂ + (1/2) O ₂ → H ₂ O (5)
The fuel cell direct current output 18 obtained by the power generation of the polymer electrolyte fuel cell stack 9 is subjected to voltage conversion and direct current to alternating current conversion by the output adjusting device 16 in accordance with the load 17, and then the alternating current at the power transmission end. The output 19 is supplied to the load 17. In FIG. 5, the output adjustment device 16 performs conversion from direct current to alternating current. However, only the voltage conversion may be performed by the output adjustment device 16 to supply the power transmission end DC output to the load 17. Although not shown in FIG. 5, the output of the fuel cell DC output 18 obtained by the power generation of the polymer electrolyte fuel cell stack 9 is adjusted according to at least one of the loads 17, 97, and 110. After the voltage conversion and the conversion from direct current to alternating current are performed by the device 16, the power transmission end AC output 19 may be supplied to at least one of the loads 17, 97, and 110. Further, only the voltage conversion may be performed by the output adjustment device 16, and the power transmission end DC output may be supplied to at least one of the loads 17, 97, and 110.

  In the air electrode 8 of the polymer electrolyte fuel cell stack 9, the supplied air 25 is exhausted as the air electrode exhaust gas 13 after a part of oxygen is consumed by the air electrode reaction shown in the equation (4). The On the other hand, in the fuel electrode 6, about 80% of the supplied hydrogen is consumed by the fuel electrode reaction shown in the equation (3), and then the remaining hydrogen is discharged as the fuel electrode hydrogen exhaust gas 59. The fuel electrode hydrogen exhaust gas 59 made of unreacted hydrogen is recycled to the fuel electrode 6 and used for power generation in order to improve the power transmission end efficiency of the polymer electrolyte fuel cell stack 9. However, since the fuel electrode hydrogen exhaust gas 59 contains some impurities other than hydrogen, these impurities gradually accumulate in the fuel electrode 6. Therefore, the purge valve 60 is intermittently opened and the purge gas 61 is released, whereby the impurity gas accumulated in the fuel electrode 6 is discharged out of the system.

  In the polymer electrolyte fuel cell stacks 95 and 108, as in the case of the polymer electrolyte fuel cell stack 9, the supply amounts of hydrogen 58 and air 25, 91, and 104 are adjusted, and the above-described battery reaction is performed. Based on this, power generation is performed, and fuel cell DC power 98, 111 is supplied to the output adjusting devices 96, 109, whereby power is supplied to the load as power transmission end AC outputs 99, 112. In this case, the fuel electrode hydrogen exhaust gas 118, 121 containing unreacted hydrogen and discharged from the fuel electrodes 92, 105 is recycled to the fuel electrodes 92, 105 in the same manner as described above. In order to suppress the accumulation of impurities in the gas, the purge valves 119 and 122 are opened intermittently and the purge gases 120 and 123 are released.

Next, problems of the conventional fuel cell power generation system as described above will be described. In the conventional fuel cell power generation system shown in FIG. 5, natural gas is supplied to the reformer burner 156 in order to cause the reformer 3 to perform a steam reforming reaction of hydrocarbons contained in the natural gas for power generation. It was necessary to burn. Further, a vaporizer 157 is provided to exchange heat with the combustion exhaust gas 166 of the reformer burner 156, and the natural gas 168 is combusted in the vaporizer burner 170, so that heat necessary for vaporizing the water 173 is externally supplied. To the vaporizer 157 to generate the steam 155 necessary for the hydrocarbon steam reforming reaction in the reformer 3. As described above, in the conventional fuel cell power generation system, natural gas and air are supplied to the reformer burner 156 and the vaporizer burner 170, and the combustion reaction between natural gas and oxygen in the air is performed. It was necessary to obtain the heat necessary to generate hydrogen by performing a steam reforming reaction of hydrocarbons. At this time, the combustion exhaust gas 166 of the reformer burner 156 and the combustion exhaust gas 175 of the vaporizer burner 170 contain a large amount of nitrogen in the air in addition to carbon dioxide and water vapor generated by the combustion of natural gas. Therefore, in order to separate and collect carbon dioxide, which is a global warming gas, an expensive and large-scale carbon dioxide separation and collection device is required. For example, a carbon dioxide absorption / release device filled with a gas absorption / release agent such as a lithium compound having the property of absorbing carbon dioxide at a predetermined temperature and releasing the absorbed carbon dioxide at a predetermined high temperature. It is possible to recover the carbon dioxide in the combustion exhaust gas 166, 175 by supplying the combustion exhaust gas 166, 175 to the gas. However, in order to continuously generate hydrogen, at least two sets of carbon dioxide are required. It is necessary to newly install an absorption / release device to perform continuous absorption / release of carbon dioxide, resulting in a problem that the system cost increases. In addition, there is a problem that the maintenance cost increases due to replacement of the gas absorption / release agent, and the carbon dioxide absorption / release device causes absorption / release of carbon dioxide depending on the temperature, resulting in an increase in energy consumption. .
JP 2002-372199 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell power generation that is friendly to the global environment, capable of recovering carbon dioxide, which is a global warming gas generated in the process of generating hydrogen necessary for power generation from fuel, and capable of high-efficiency power generation. To provide a system.

  A first fuel cell power generation system according to the present invention is a fuel cell power generation system that generates power by electrochemically reacting hydrogen and oxygen. The fuel storage unit stores a water-soluble organic compound aqueous solution, and is supplied from the fuel storage unit. Electrolysis means that electrolyzes the water-soluble organic compound aqueous solution to separate and produce hydrogen and carbon dioxide, and carbon dioxide recovery that collects the carbon dioxide produced by separation by the electrolysis means and supplies it to the fuel storage means Means, a hydrogen recovery means for recovering the hydrogen separated and generated by the electrolysis means, a fuel cell stack, and a hydrogen supply means for supplying the hydrogen recovered by the hydrogen recovery means to the fuel cell stack. The fuel cell stack performs power generation by causing an electrochemical reaction between hydrogen and oxygen supplied by the hydrogen supply means.

  A second fuel cell power generation system according to the present invention is a fuel cell power generation system that generates power by electrochemically reacting hydrogen and oxygen to separate hydrogen and carbon dioxide by electrolyzing an aqueous solution of a water-soluble organic compound. Generating means, carbon dioxide recovery means for recovering carbon dioxide separated and generated by the electrolytic means, and carbon dioxide supply means for supplying the carbon dioxide recovered by the carbon dioxide recovery means to the carbon dioxide supply destination And hydrogen recovery means for recovering the hydrogen separated and generated by the electrolysis means, a fuel cell stack, and a hydrogen supply means for supplying the hydrogen recovered by the hydrogen recovery means to the fuel cell stack, The fuel cell stack is characterized in that it generates electric power by causing an electrochemical reaction between hydrogen and oxygen supplied by a hydrogen supply means. In this fuel cell power generation system, carbon dioxide storage means for storing carbon dioxide recovered by the carbon dioxide recovery means may be provided.

  In the fuel cell power generation system of the present invention, a hydrogen purification means for purifying the hydrogen recovered by the hydrogen recovery means may be provided. In that case, a hydrogen storage means for storing the hydrogen purified by the hydrogen purification means, a hydrogen purification means You may provide the hydrogen pressurization means to pressurize the hydrogen refine | purified by the means.

Above the first and second fuel cell power generation system of the present invention, the carbon dioxide recovered by the in recovered hydrogen and carbon dioxide recovery means hydrogen recovery unit is supplied, the sub-components of the supplied carbon dioxide It further has an oxygen reaction means for reacting oxygen and hydrogen contained therein to generate water or water vapor. In the case where hydrogen purification means is provided, the oxygen reaction means is supplied with exhaust gas from the hydrogen purification means instead of hydrogen recovered by the hydrogen recovery means, and removes hydrogen contained in the exhaust gas. Ru is reacted with oxygen in the carbon dioxide. In any case, it is preferable to provide a water recovery means for recovering water or water vapor generated by the oxygen reaction means.

  In the fuel cell power generation system of the present invention, a hydrogen pressurizing unit that pressurizes the hydrogen recovered by the hydrogen recovery unit may be provided, or a hydrogen storage unit that stores the hydrogen pressurized by the hydrogen pressurizing unit may be provided. It is also possible to provide hydrogen storage means for storing hydrogen recovered by the hydrogen recovery means.

  In the present invention, as the fuel cell stack, for example, a solid polymer fuel cell stack using a solid polymer electrolyte membrane as an electrolyte or a phosphoric acid fuel cell stack using phosphoric acid as an electrolyte is used. As the water-soluble organic compound, for example, at least one compound selected from the group consisting of methanol, ethanol, and 2-propanol is used.

  According to the present invention, by electrolyzing a water-soluble organic compound aqueous solution in an electrolysis cell constituting an electrolysis device of a fuel cell power generation system, the electrolysis cell anode can be selected with less electrolysis power than water electrolysis. Separation of hydrogen because it is possible to generate an anode chamber outlet gas containing a high concentration of carbon dioxide and to selectively generate a cathode chamber outlet gas containing a high concentration of hydrogen at the cathode of the counter electrode. Recovery and separation and recovery of carbon dioxide are easy. For this reason, it is possible to reduce running costs such as system cost, maintenance cost, and energy cost for collecting carbon dioxide, which is a global warming gas. Furthermore, according to the present invention, since the hydrogen concentration in the recovered cathode chamber outlet gas is high, it is possible to suppress the loss of hydrogen in the hydrogen purification means and to reduce the system cost by making the hydrogen purification means compact. . Therefore, according to the wood invention, there is an advantage that carbon dioxide can be easily recovered and high-efficiency power generation is possible.

  Next, a preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows the configuration of a fuel cell power generation system according to an embodiment of the present invention. In the example shown in FIG. 1, three sets of polymer electrolyte fuel cell stacks 9, 95, 108 are used, but the number of polymer electrolyte fuel cell stacks is not necessarily limited to three. Any number of polymer electrolyte fuel cell stacks may be used.

The fuel cell power generation system shown in FIG. 1 includes, as main components, a polymer electrolyte fuel cell stack 9, 95, 108 and a fuel storage unit that stores the methanol aqueous solution 5 and also stores the recovered carbon dioxide. 11, output regulators 16, 96, and 109 that convert DC power generated in the polymer electrolyte fuel cell stacks 9, 95, and 108 into AC power, and an electrolytic device 20 that causes the aqueous methanol solution 5 to perform an electrolysis reaction The pumps 23 and 77, the DC power source 26 for supplying the DC power 46 necessary for the electrolysis of the aqueous methanol solution 5 to the electrolysis device 20, and the hydrogen generated by the electrolysis device 2 to be recovered as the cathode chamber outlet gas 65 a recovery device 28 (FIG. 1 labeled "H ₂ recovery"), to recover the carbon dioxide was generated by the electrolysis apparatus 2 as the anode chamber outlet gas 64 diacid Carbon recovery device 29 (labeled in FIG. 1 "CO ₂ recovery"), and flow control valve 31,34～36, a hydrogen purification device 67 to purify the cathode chamber outlet gas 65 obtain highly pure hydrogen 78, cathode A hydrogen pressurizer 62 that pressurizes the chamber outlet gas 65 to generate a pressurized cathode chamber outlet gas 75; a hydrogen pressurizer 37 that pressurizes the high purity hydrogen 78 to generate pressurized high purity hydrogen 79; Hydrogen storage units 38, 39, and 63 that hold pressurized high-purity hydrogen 79, high-purity hydrogen 78, and pressurized cathode chamber outlet gas 75, respectively, and high-purity hydrogen stored in the hydrogen storage units 38 and 39 in solid polymer form Hydrogen supply devices 40, 41 for supplying the fuel cell stacks 9, 95, 108, a hydrogen supply device 84 for supplying the cathode chamber outlet gas stored in the hydrogen storage unit 63 to the polymer electrolyte fuel cell stack, two The carbon dioxide pressurizing device 42 that pressurizes the anode chamber outlet gas 64 recovered by the carbonized carbon recovery device 29 to generate the pressurized anode chamber outlet gas 66 and supplies the pressurized anode chamber outlet gas 66 to the fuel storage unit 11, and the anode chamber outlet gas 64 An oxygen reaction device 43 for reacting oxygen, a water recovery device 44 for recovering water or water vapor from the effluent or exhaust gas of the oxygen reaction device 43, purge valves 60, 119, 122, and flow control valves 10, 76, 86 to 88, 90, 103 and air supply blowers 89, 102, 115 are provided. That is, the fuel cell power generation system of the present embodiment shown in FIG. 1 is different from the conventional fuel cell power generation system shown in FIG. 5 in that the desulfurizer 2, the reformer 3, the CO shift converter 4, the hydrogen separator 53, The condenser 55, the vaporizer 157, the water tank 159, and the vaporizer burner 170 are not necessary. Instead, the fuel storage unit 11, the electrolysis device 20, the DC power supply 26, the hydrogen recovery device 28, the carbon dioxide recovery device 29, hydrogen Pressurization devices 37, 62, hydrogen storage units 38, 39, 63, hydrogen supply devices 40, 41, 84, carbon dioxide pressurization device 42, oxygen reaction device 43, moisture recovery device 44, and hydrogen purification device 67 were provided. It is very different in terms.

  In FIG. 1, the same parts as those in FIG. 5 described above are denoted by the same reference numerals, and detailed description of these parts is omitted. In particular, in the fuel cell power generation system shown in FIG. 1, the configuration of the part on the polymer electrolyte fuel cell stack 9 side from the flow control valve 86, and the part on the polymer electrolyte fuel cell stack 95 side from the flow control valve 87. 5 and the configuration of the portion on the polymer electrolyte fuel cell stack 108 side from the flow rate control valve 88 are completely the same as the configuration of the corresponding portion shown in FIG.

  The fuel storage unit 11 is a replaceable tank that stores an aqueous methanol solution 5 that is one of aqueous solutions of water-soluble organic compounds. Instead of the aqueous methanol solution 5, an aqueous ethanol solution, an aqueous 2-propanol solution, or the like may be used as an aqueous solution of the water-soluble organic compound. As will be described later, the molar ratio of methanol and water in the aqueous methanol solution 5 is 1: 1 because methanol and water are reacted in an equimolar amount to generate hydrogen, but is not necessarily limited to 1: 1. . The aqueous methanol solution 5 stored in the fuel storage unit 11 is supplied by the pump 23 to the anode chamber 68 of the electrolysis cell 74 constituting the electrolysis apparatus 30. The configuration of the electrolysis cell 74 is shown in FIG.

The electrolysis cell 74 includes an anode 69, an anode chamber 68 including the anode 69, an electrolyte membrane 70, a cathode 71, and a cathode chamber 72 including the cathode 71. The electrolyte membrane 70 separates the anode chamber 68 and the cathode chamber 72, and the anode 69 and the cathode 71 are provided in contact with the electrolyte membrane 70 so as to sandwich the electrolyte membrane 70. Proton (H ⁺ ) generated at the anode 69 moves through the electrolyte membrane 7 and reaches the cathode 69. In FIG. 2, the electrolysis apparatus 20 is configured by a set of electrolysis cells 74, but is not necessarily limited to one set, and the electrolysis apparatus 2 may be configured by a plurality of sets of electrolysis cells 74. .

  The supply amount of the methanol aqueous solution 5 to the anode chamber 68 of the electrolysis cell 74 is between the sum of the battery currents of the fuel cell DC outputs 18, 98, 111 and the rotational speed of the pump 23 (that is, the supply amount of the methanol aqueous solution 5). By controlling the rotational speed of the pump 23 based on the previously set relationship, the value is set to a value corresponding to the sum of the battery currents of the fuel cell DC outputs 18, 98, and 111.

  The DC power source 26 is supplied with electric power 45 obtained from a predetermined energy source such as a private power generator such as a solar cell, a wind power generator, a fuel cell, a gas engine, a diesel engine, or a gas turbine, or a commercial power source. The electric power 45 supplied to the DC power supply 26 is subjected to predetermined conversion by the DC power supply 26, supplied to the electrolysis cell 74 in the form of DC power 46, and the electricity of the aqueous methanol solution 5 supplied to the anode chamber 68 of the electrolysis cell 74. Used for disassembly. The amount of DC power 46 supplied to the electrolysis cell 74 is determined based on a preset relationship between the sum of the battery currents of the fuel cell DC outputs 18, 98, and 111 and the amount of DC power 46 current. By controlling the power supply 26, the value is set to a value corresponding to the sum of the battery currents of the fuel cell DC outputs 18, 98, and 111.

The DC power 46 supplied from the DC power source 26 to the electrolysis cell 74 applies an electrolysis voltage between the anode 69 and the cathode 71 of the electrolysis cell 74, and an electrolysis current flows, thereby electrolyzing the aqueous methanol solution 3. Occur. At the anode 69, an electrochemical reaction of methanol (CH ₃ OH) and water (H ₂ O) shown in the formula (6) occurs, and carbon dioxide (CO ₂ ), proton (H ⁺ ), and electrons (e ⁻ ) are generated. .

_{CH 3 OH + H 2 O →} CO 2 + 6H + + 6e - (6)
A catalyst is required to advance the electrochemical reaction of methanol and water at the anode 69, and a platinum catalyst in which platinum or a platinum-ruthenium alloy is supported on a carbon carrier or the like, or a platinum-ruthenium alloy catalyst is generally used. It has been. Proton (H ⁺ ) generated at the anode 69 by the electrochemical reaction of methanol and water shown in the formula (6) moves through the electrolyte membrane 70 having proton conductivity and reaches the cathode 71. For the electrolyte membrane 70 having proton conductivity, a perfluorosulfonic acid membrane having a sulfonic acid group is often used. Further, the electrons (e ⁻ ) generated at the anode 69 by the electrochemical reaction of methanol and water shown in the equation (6) travel through an external circuit including the DC power supply 26 and reach the cathode 71. In the cathode 71, as shown in the equation (4), an electrochemical reaction occurs between protons moving from the anode 69 in the electrolyte membrane 70 and electrons moving from the anode 69 in the external circuit, and hydrogen is generated.

_{^{6H + + 6e - → 3H 2}} (7)
The electrolysis reaction of the aqueous methanol solution 5 is a combination of the reaction at the anode 69 shown in the formula (6) and the reaction at the cathode 71 shown in the formula (7). As shown in the above, methanol and water react to produce carbon dioxide and hydrogen.

CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ (8)
As described above, carbon dioxide is generated at the anode 69 of the electrolysis cell 74 of the electrolysis device 20, and hydrogen is generated at the cathode 71. Since the gas tightness of the electrolyte membrane 70 of the electrolytic cell 74 is high, the possibility that carbon dioxide generated at the anode 69 and hydrogen generated at the cathode 71 are mixed is low. Therefore, by using such an electrolysis apparatus 20, hydrogen and carbon dioxide can be separated and recovered from the electrolysis cell 74. The carbon dioxide generated at the anode 69 is separated from the unreacted methanol aqueous solution 47 and recovered as the anode chamber outlet gas 64 in the carbon dioxide recovery device 29 provided adjacent to the anode chamber 68. A part of the methanol aqueous solution supplied to the anode chamber 68 of the electrolysis cell 74 may permeate the electrolyte membrane 70 and move to the cathode chamber 72. In this case, hydrogen generated in the cathode 71 is transferred to the cathode chamber. 72 is separated from the aqueous methanol solution 73 that has permeated through the electrolyte membrane 70 in the hydrogen recovery device 28 provided adjacent to 72 and recovered as the cathode chamber outlet gas 65.

  The methanol concentration of the unreacted methanol aqueous solution 47 separated from the anode chamber outlet gas 64 by the carbon dioxide recovery device 29 and the methanol of the methanol aqueous solution 73 permeated through the electrolyte membrane 70 separated from the cathode chamber outlet gas 65 by the hydrogen recovery device 28. Since the concentration is substantially equal to the methanol concentration of the aqueous methanol solution 5 supplied to the anode chamber 68 of the electrolytic cell 74, the unreacted aqueous methanol solution 47 separated by the carbon dioxide recovery device 29 and the electrolyte membrane separated by the hydrogen recovery device 28. The methanol aqueous solution 73 that has permeated 70 is recycled to the fuel storage unit 11 or the anode chamber 68 of the electrolysis cell 74 as necessary. The aqueous methanol solution 73 that has passed through the electrolyte membrane 70 separated by the hydrogen recovery device 28 is sent to a pump 77. The outlet of the pump 77 branches into two branches, one leading to the fuel storage unit 11 via the flow control valve 35 and the other connected to the supply line connecting the pump 23 and the electrolyzer 20 via the flow control valve 36. . Similarly, the outlet for discharging the unreacted methanol aqueous solution 47 of the carbon dioxide recovery device 29 branches into two branches, one leading to the fuel storage unit 11 via the flow control valve 31 and the other via the flow control valve 34 to the pump 23. And a supply pipe connecting the electrolyzer 20. Therefore, the recycle amounts of the unreacted aqueous methanol solution 47 separated by the carbon dioxide recovery device 29 to the fuel storage unit 11 and the anode chamber 68 of the electrolysis cell 74 are adjusted by adjusting the opening degree of the flow control valves 31 and 34, respectively. Controlled by. Similarly, the recycle amounts of the aqueous methanol solution 73 permeated through the electrolyte membrane 70 separated by the hydrogen recovery device 28 to the fuel storage unit 11 and the anode chamber 68 of the electrolysis cell 74 are the opening amounts of the flow control valves 35 and 36, respectively. Is controlled by adjusting.

  The cathode chamber outlet gas 65 containing hydrogen generated at the cathode 71 of the electrolysis cell 74 of the electrolysis device 20 is supplied to a hydrogen purification device 67 such as a hydrogen separator having a hydrogen separation membrane represented by a palladium membrane, for example. Supply high purity hydrogen 78. The high-purity hydrogen 78 produced by the hydrogen purification device 67 is supplied to the hydrogen pressurization device 37 and pressurized as necessary, and then supplied as the pressurized high-purity hydrogen 79 to the hydrogen storage unit 38 such as a high-pressure tank. And stored. On the other hand, the gas containing impurities separated and removed by the hydrogen purification device 67 is discharged from the hydrogen purification device 67 as a hydrogen purification device exhaust gas 80. The pressurized high-purity hydrogen 79 stored in the hydrogen storage unit 38 is supplied to the fuel electrode 6 of the polymer electrolyte fuel cell stack 9 or the polymer electrolyte fuel cell stack using the hydrogen supply device 40 as necessary. 95 fuel electrodes 92 and the fuel electrode 105 of the polymer electrolyte fuel cell stack 108 are supplied. In the hydrogen supply device 40, the pressurized high-purity hydrogen 79 is depressurized as necessary. The hydrogen pressurizing device 37 and the hydrogen storage unit 38 are not provided, and the high-purity hydrogen 78 is directly used as the fuel electrode 6 of the polymer electrolyte fuel cell stack 9 and the polymer electrolyte fuel cell using the hydrogen supply device 40. The fuel electrode 92 of the stack 95 and the fuel electrode 105 of the polymer electrolyte fuel cell stack 108 may be supplied.

  The high-purity hydrogen 78 produced by the hydrogen purifier 67 may be stored at normal pressure in the hydrogen storage unit 39 such as a hydrogen storage alloy tank without being pressurized by the hydrogen pressurizer 37. Also in this case, the high-purity hydrogen 78 stored in the hydrogen storage unit 39 is used as it is, using the hydrogen supply device 41, as the fuel electrode 6 of the polymer electrolyte fuel cell stack 9, the polymer electrolyte fuel cell stack. 95 fuel electrodes 92 and the fuel electrode 105 of the polymer electrolyte fuel cell stack 108 are supplied. The hydrogen supply device 41 pressurizes the high purity hydrogen 78 as necessary. The hydrogen storage unit 39 is not provided, and high-purity hydrogen 78 is directly supplied to the fuel electrode 6 of the polymer electrolyte fuel cell stack 9 and the fuel electrode 92 of the polymer electrolyte fuel cell stack 95 using the hydrogen supply device 41. Alternatively, the fuel electrode 105 of the polymer electrolyte fuel cell stack 108 may be supplied.

  Further, the cathode chamber outlet gas 65 may be supplied to the hydrogen pressurizing device 62 as it is and then pressurized, and then supplied as the pressurized cathode chamber outlet gas 75 to the hydrogen storage unit 63 and stored in the hydrogen storage unit 63. In this case, the pressurized cathode chamber outlet gas 75 stored in the hydrogen storage section 63 is supplied to the fuel electrode 6 of the polymer electrolyte fuel cell stack 9, the solid high The fuel electrode 92 of the molecular fuel cell stack 95 and the fuel electrode 105 of the polymer electrolyte fuel cell stack 108 are supplied. In the hydrogen supply device 84, the pressurized cathode chamber outlet gas 75 is depressurized as necessary. The hydrogen pressurizing device 62 and the hydrogen storage unit 63 are not provided, and the cathode chamber outlet gas 65 is directly used as the fuel electrode 6 of the polymer electrolyte fuel cell stack 9 and the polymer electrolyte fuel cell using the hydrogen supply device 84. The fuel electrode 92 of the cell stack 95 and the fuel electrode 105 of the polymer electrolyte fuel cell stack 108 may be supplied.

  Without purifying the cathode chamber outlet gas 83, the fuel electrode 6 of the polymer electrolyte fuel cell stack 9, the fuel electrode 92 of the polymer electrolyte fuel cell stack 95, the polymer electrolyte fuel cell stack as it is. When the fuel electrode 105 is supplied to the fuel electrode 105, the purity of hydrogen in the cathode chamber outlet gas 83 is lower than that of the high-purity hydrogen 78, so that the fuel electrode hydrogen exhaust gas 59, 118, There is a possibility that impurities other than hydrogen are contained in 121. Therefore, when the cathode chamber outlet gas 83 is supplied as it is to the fuel electrodes 59, 92, 105, the fuel electrode hydrogen exhaust gas 59, 118, 121 is released as it is without being recycled to the fuel electrodes 6, 92, 105. It is preferable.

  The supply amount of the high purity hydrogen 81 or the high purity hydrogen 82 or the cathode chamber outlet gas 83 to the fuel electrode 6 of the polymer electrolyte fuel cell stack 9 depends on the battery current of the fuel cell DC output 18 and the opening of the flow control valve 86. The degree of opening of the flow rate control valve 86 is controlled based on a preset relationship between the degree of flow (that is, the supply amount of the high purity hydrogen 81 or the high purity hydrogen 82 or the cathode chamber outlet gas 83 to the fuel electrode 6). By doing so, a value corresponding to the battery current of the fuel cell DC output 18 is set. Similarly, the supply amount of the high-purity hydrogen 81, the high-purity hydrogen 82, or the cathode chamber outlet gas 83 to the fuel electrode 92 of the polymer electrolyte fuel cell stack 95 is determined based on a preset relationship. By controlling the opening degree of 87, it is set to a value commensurate with the battery current of the fuel cell DC output 98, and high purity hydrogen 81 or high purity hydrogen 82 to the fuel electrode 105 of the polymer electrolyte fuel cell stack 108 is set. Alternatively, the supply amount of the cathode chamber outlet gas 83 is set to a value commensurate with the battery current of the fuel cell DC output 111 by controlling the opening degree of the flow rate control valve 88 based on a preset relationship.

  In the fuel cell power generation system of this embodiment, the carbon dioxide concentration of the anode chamber outlet gas 64 containing carbon dioxide generated at the anode 69 of the electrolysis cell 74 of the electrolysis device 20 is as high as 90% by volume or more. Therefore, in the fuel cell power generation system of this embodiment, it is not necessary to newly provide a carbon dioxide absorption / release device that absorbs and releases carbon dioxide in order to separate and recover carbon dioxide, and energy to separate and recover carbon dioxide. There is no need to consume. By recovering the anode chamber outlet gas 64 as it is, it is possible to efficiently recover carbon dioxide.

  In addition, in the anode 69 of the electrolysis cell 74 of the electrolysis apparatus 20, in addition to the electrochemical reaction of methanol and water shown in the formula (6), an electrolysis reaction of water shown in the formula (9) also takes place. The anode chamber outlet gas 64 containing the high concentration carbon dioxide recovered in 29 may contain some oxygen.

H ₂ O → (1/2) O ₂ + 2H ⁺ + 2e ⁻ (9)
Therefore, in this embodiment, an oxygen reaction device 43 such as a catalytic combustor using a noble metal catalyst such as platinum is provided as necessary, and an anode outlet gas 64 and a cathode chamber outlet gas 65 containing high concentration hydrogen are provided as oxygen. Supplying to the reactor 72, the oxygen in the anode chamber outlet gas 64 and the hydrogen in the cathode chamber outlet gas 65 are combusted by the combustion reaction shown in the equation (10) to generate water or water vapor, and the anode chamber outlet gas 64 Remove oxygen inside.

(1/2) O ₂ + H ₂ → H ₂ O (10)
The supply amount of the cathode chamber outlet gas 65 to the oxygen reactor 43 is the sum of the battery currents of the fuel cell DC outputs 18, 98, 111 and the opening of the flow control valve 76 (that is, the cathode chamber outlet to the oxygen reactor 43). The value corresponding to the sum of the battery currents of the fuel cell DC outputs 18, 98, and 111 by controlling the opening degree of the flow control valve 76 based on a preset relationship with the gas 65 supply amount). Set to In addition, instead of the cathode chamber outlet gas 65, the hydrogen purifier exhaust gas 80 containing hydrogen may be supplied to the oxygen reactor 43 in the same manner.

  Water or water vapor generated in the oxygen reaction device 43 is recovered by providing a water recovery device 44 such as a condenser or a water adsorber (filled with silica gel or the like) as necessary. The anode chamber outlet gas 64 from which water or water vapor has been recovered by the moisture recovery device 44 is pressurized by the carbon dioxide pressurizing device 42 as necessary, and then supplied to the fuel storage unit 11 as a pressurized anode chamber outlet gas 66. Stored. The pressurized anode chamber outlet gas 66 containing high-concentration carbon dioxide stored in the fuel storage unit 11 is replaced with the fuel storage unit 11 when the methanol aqueous solution 5 stored in the fuel storage unit 11 runs out. Can be recovered. Since the anode chamber outlet gas 64 can be pressurized to about several atmospheres (several hundred kPa) by the electrolyzer 20, carbon dioxide is directly supplied without providing the carbon dioxide pressurizing device 42 to pressurize the anode chamber outlet gas 64. It is also possible to supply the anode chamber outlet gas 64 including the fuel storage unit 11.

  Since carbon dioxide is an inert gas, there is no danger even if it is stored in the gas phase portion of the fuel storage unit 11 that stores the aqueous methanol solution 5. Since the fuel storage unit 11 is in a depressurized state as the methanol aqueous solution 5 is consumed, if the carbon dioxide, that is, the anode chamber outlet gas 64 is supplied to the fuel storage unit 11, the depressurization can be suppressed. There is also an advantage that the electrolytic device 20 can be smoothly supplied.

  In the present embodiment, the pressurized anode chamber outlet gas 66 or the anode chamber outlet gas 64 is stored in the fuel storage unit 11, but a carbon dioxide storage unit and a carbon dioxide supply device are separately provided, and the pressurized anode chamber outlet gas 66 is provided. Alternatively, the anode chamber outlet gas 64 is stored in the carbon dioxide storage section, and the pressurized anode chamber outlet gas 66 or the anode chamber outlet gas 64 stored in the carbon dioxide storage section is stored in a tank truck as required using a carbon dioxide supply device. Even if it supplies to a carbon dioxide processing apparatus by the above, the same effect as this embodiment is acquired. The carbon dioxide treatment device here includes a device for treating and fixing the carbon dioxide without releasing the carbon dioxide into the environment. Further, even if a carbon dioxide supply device is separately provided and the pressurized anode chamber outlet gas 66 or the anode chamber outlet gas 64 is supplied to the carbon dioxide processing device by a pipeline using the carbon dioxide supply device, the same as in the present embodiment. Effects can be obtained.

  In the fuel cell power generation system of this embodiment shown in FIG. 1, hydrogen pressurization devices 37 and 62, hydrogen storage units 38, 39, and 63, a carbon dioxide pressurization device 42, an oxygen reaction device 43, a moisture recovery device 44, and The hydrogen purifier 67 is not indispensable for carrying out the present invention, and can be appropriately provided as necessary.

  In the fuel cell power generation system of this embodiment, the carbon dioxide recovery device 29 adjacent to the anode chamber 68 of the electrolysis cell 74 of the electrolysis device 20 converts high-concentration carbon dioxide having a carbon dioxide concentration of 90% by volume or more into the anode chamber outlet gas. Therefore, a carbon dioxide absorption / release device for absorbing and releasing carbon dioxide for separating and recovering carbon dioxide is not necessary. Further, in the fuel cell power generation system of the present embodiment, it is not necessary to provide a storage tank for storing only carbon dioxide, and the recovered carbon dioxide is stored in the fuel storage unit 11 that stores the methanol aqueous solution as fuel. Therefore, by replacing the fuel storage unit 11, fuel supply and carbon dioxide recovery can be easily performed simultaneously. Therefore, according to this embodiment, the system cost necessary for installing the carbon dioxide absorption / release device, the running cost such as the maintenance cost, and the energy cost can be reduced, and the tank for storing only carbon dioxide is installed. It is possible to reduce the system cost required for the fuel cell, and it is possible to realize a fuel cell power generation system capable of recovering carbon dioxide economically.

  Furthermore, in the fuel cell power generation system of the present embodiment, the hydrogen recovery device 28 adjacent to the cathode chamber 72 of the electrolysis cell 74 of the electrolysis device 20 causes high concentration hydrogen having a hydrogen concentration of 90% by volume or more as the cathode chamber outlet gas 65. Since the cathode chamber outlet gas can be recovered, it can be supplied to the polymer electrolyte fuel cell stack 9, 95, 108 as it is. Even when the high purity hydrogen 81 or the high purity hydrogen 82 obtained by refining the cathode chamber outlet gas 65 with the hydrogen purifier 67 is supplied to the polymer electrolyte fuel cell stack 9, 95, 108, the electrolysis cell 74 is used. The cathode chamber outlet gas 65 can be pressurized to several atmospheres (several hundred kPa) by using electrolysis in the cathode chamber, so that the cathode chamber is used to obtain a pressure required for the hydrogen purifier 67 using membrane separation. A separate pressurizing device for pressurizing the outlet gas 65 can be eliminated. Further, since the hydrogen concentration in the cathode chamber outlet gas 65 is high, the hydrogen purifier can be made compact. Therefore, the system cost and energy cost of the fuel cell power generation system can be reduced.

In the fuel cell power generation system of this embodiment, in order to electrolyze the methanol aqueous solution 5 by the electrolytic cell 74 in the electrolysis apparatus 20, the electric power 45 obtained from a predetermined energy source is supplied from the DC power source 26 to the predetermined DC power 45. However, as shown in FIG. 3, the electrolysis voltage of the aqueous methanol solution is 30 to 42% of the electrolysis voltage of water. Since the electrolysis power is determined by the electrolysis voltage, considering the electrolysis power necessary for obtaining the same number of moles of hydrogen, the electrolysis power in the case of electrolysis of aqueous methanol solution is 30 to 30% of the electrolysis power in the case of electrolysis of water. 42%. Therefore, the fuel cell power generation system of this embodiment does not cause an increase in energy cost due to an increase in energy consumption, as compared with a conventional fuel cell power generation system using water electrolysis. 3 shows a platinum-ruthenium catalyst (electrolysis of aqueous methanol solution) or platinum catalyst (electrolysis of water) as the catalyst of the anode 69 of the electrolytic cell 74, a platinum catalyst as the catalyst of the cathode 71, and the electrolyte membrane 70. It shows the relationship between electrolysis voltage and electrolysis current when electrolysis of aqueous methanol solution and electrolysis of water are performed using perfluorosulfonic acid films, respectively. The concentration of the aqueous methanol solution supplied to the anode chamber 68 of the electrolysis cell 74 was 17 mol / l (molar ratio of methanol to water was 1: 1), and the supply amount of the aqueous methanol solution 3 was 5 cm ³ / min. The effective electrode surface areas of the anode 69 and the cathode 71 of the electrolytic cell 74 were 23 cm ² . Note that the electrolysis voltage of the aqueous methanol solution was reduced to 30 to 42% compared to the electrolysis voltage of water. However, as shown in FIG. It was confirmed that hydrogen was produced at the theoretical production rate.

  In the above description, the polymer electrolyte fuel cell stack is used as the fuel cell stack, but the fuel cell stack used in the fuel cell power generation system of the present invention is not limited to this. In the fuel cell power generation system according to the present invention, the same effect can be obtained by using a phosphoric acid fuel cell stack using a phosphoric acid electrolyte as an electrolyte instead of the solid polymer fuel fuel cell stack. At that time, all of the polymer electrolyte fuel cell stack may be replaced with a phosphoric acid fuel cell stack, or part of the polymer electrolyte fuel cell stack may be replaced with a phosphoric acid fuel cell stack. And phosphoric acid fuel cell stack may be mixed. When a phosphoric acid fuel cell stack is used, the fuel electrode reaction, the air electrode reaction, and the battery reaction are the same as those when the polymer electrolyte fuel cell stack is used as the electrode reaction formula. However, since the operating temperature is as high as about 200 ° C., water vapor is generated by the battery reaction. This water vapor can be used for air conditioning in addition to hot water supply.

  The fuel cell power generation system according to the present invention described above can also be realized by using an aqueous solution of another aqueous organic compound as a fuel instead of an aqueous methanol solution. The water-soluble organic compound used in the present invention is not particularly limited as long as it is a water-soluble organic compound, but among them, an organic compound that dissolves in an arbitrary ratio with respect to water is preferable. Also preferred are organic compounds whose constituent elements are hydrogen, carbon, and optionally oxygen. Specific examples of water-soluble organic compounds that can be used in the present invention include water-soluble alcohols, organic acids, ketones, amines, nitroalkanes, ethers (including cyclic ethers), aldehydes, or derivatives thereof. Can be mentioned. Alcohols, organic acids, ketones, amines, nitroalkanes, ethers, and aldehydes preferably have about 1 to 20 carbon atoms. The cyclic ether preferably has a 4- to 6-membered ring skeleton, and the number of carbon atoms in the cyclic ether is preferably about 5 to 10.

  Examples of the water-soluble alcohol include methanol, ethanol, normal propanol, isobropanol (2-propanol), normal butanol, isobutanol, sec-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 5-methyl-1-hexanol, isoamyl alcohol (3-methyl-1-butanol), sec-isoamyl alcohol (3-methyl- 2-butanol), isoundecylene alcohol, isooctanol, isopentanol, isogeranol, isohexanol, 2,4-dimethyl-1-pentanol, 2,4,4-trimethyl-1-pentanol, etc. Monovalent alcohol with 1-20 atoms , Dihydric alcohols such as ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,2-propanediol, 1,2-pentanediol, or butanetriol, glycerin, di Examples thereof include polyhydric alcohols having 3 to 10 carbon atoms such as glycerin.

  Examples of the water-soluble organic acid include acetic acid and propionic acid. Examples of the water-soluble ketone include acetone, methyl ethyl ketone, cyclohexanone, cyclooctanone, cyclodecanone, and isophorone. Examples of the water-soluble amine include methylamine and ethylamine. Examples of the nitroalkane having water solubility include nitroethane. Examples of the water-soluble ether include dimethyl ether, diethyl ether, polyoxyethylene phenyl ether, polyoxyethylene octyl phenyl ether, and the like. Examples of the water-soluble cyclic ether include tetrahydrofuran, 1,4-dioxane, 1,3-dioxane and the like. Examples of the water-soluble aldehyde include formaldehyde and acetaldehyde.

  Other water-soluble organic compounds that can be used in the present invention include esters such as ethyl acetate, ethylene glycol alkyl ethers such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, and acetates thereof, ethyl carbitol, butyl carbitol, and the like. Diethylene glycol alkyl ethers and acetates thereof, propylene glycol alkyl ethers and acetates thereof, monohydric alcohols having 4 to 30 carbon atoms, phenolic compounds having 6 to 30 carbon atoms, alkylene having 6 to 30 carbon atoms An active hydrogen-containing compound composed of a polyamine having 2 to 6 carbon atoms (2 to 4 nitrogen atoms) such as glycol, polyhydric alcohol having 6 to 30 carbon atoms, ethylenediamine, diethylenepolyamine, etc. Water-soluble liquid alkylene oxide adducts with added pyrene oxide (1 to 10 moles of ethylene oxide), water-soluble polymers such as polyvinyl alcohol, various sugars such as saccharose and glucose, water-soluble polymers such as methyl cellulose and water-soluble starch Examples thereof include saccharides or derivatives thereof.

  Especially, as a water-soluble organic compound used by this invention, a C3-C10 polyhydric alcohol, a C1-C20 monohydric alcohol, and a C3-C20 ketone are preferable, Furthermore, Alcohols such as methanol, ethanol and 2-propanol are more preferable. As the water-soluble organic compound used in the present invention, only one kind of compound as described above may be used alone, or two or more kinds of compounds as described above may be used in combination. In the present invention, the aqueous solution of the water-soluble organic compound may contain other components as long as it contains the water-soluble organic compound as described above.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications are made without departing from the spirit of the present invention.

It is a figure which shows the structure of the fuel cell power generation system of one Embodiment of this invention. It is a figure which shows the structure of the electrolysis cell used with the electrolysis apparatus in the fuel cell power generation system shown in FIG. It is a graph which shows the relationship between the electrolysis voltage and the electrolysis current in the electrolysis of methanol aqueous solution and the electrolysis of water. It is a graph which shows the relationship between the hydrogen production | generation rate and electrolysis current in the electrolysis of methanol aqueous solution. It is a figure which shows the structure of the conventional fuel cell power generation system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Natural gas 2 Desulfurizer 3 Reformer 4 CO shift converter 5 Methanol aqueous solution 6,92,105 Fuel electrode 7,93,106 Solid polymer electrolyte 8,94,107 Air electrode 9,95,108 Solid polymer fuel Battery cell stack 10, 27, 31, 33 to 36, 76, 86 to 88, 90, 103, 162, 164, 167, 171, 174 Flow control valve 11 Fuel storage unit 12, 89, 102, 115 Air supply blower 13, 100, 113 Air electrode exhaust gas 14, 25, 91, 104, 165, 172 Air 16, 96, 109 Output regulator 17, 97, 110 Load 18, 98, 111 Fuel cell DC output 19, 99, 112 Power transmission End AC output 20 Electrolytic device 21 CO shift converter outlet gas 22 Hydrogen-rich reformed gas 23,77 Pump 4 Desulfurized natural gas 26 DC power supply 28 Hydrogen recovery device 29 Carbon dioxide recovery device 30, 116, 117 Product water 32 Desulfurizer recycle gas 37, 62 Hydrogen pressurization device 38, 39, 63 Hydrogen storage unit 40, 41, 84 Hydrogen supply Equipment 42 Carbon dioxide pressurizing equipment 43 Oxygen reactor 44 Moisture recovery equipment 45 Power 46 DC power 47 Unreacted methanol aqueous solution 52 Hydrogen separator supply gas 53 Hydrogen separator 54 Hydrogen separator exhaust gas 55 Condenser 56 Hydrogen separator dry operation Exhaust gas 57 Condensed water 58 Hydrogen 59, 118, 121 Fuel electrode hydrogen exhaust gas 60, 119, 122 Purge valve 61, 120, 123 Purge gas 64 Anode chamber outlet gas 65, 83 Cathode chamber outlet gas 66 Pressurized anode chamber outlet gas 67 Hydrogen purification equipment 68 Anode chamber 69 Anode 70 Electrolysis Membrane 71 Cathode 72 Cathode chamber 73 Methanol aqueous solution permeated through electrolyte membrane 74 Electrolysis cell 75 Pressurized cathode chamber outlet gas 78, 81, 82 High purity hydrogen 79 Pressurized high purity hydrogen 80 Hydrogen purifier exhaust gas 154 Mixed gas 155 Water vapor 156 reformer burner 157 vaporizer 158 vaporizer pump 159 water tank 160 makeup water 161 makeup water pumps 166, 175 combustion exhaust gas 170 vaporizer burner 173 water 176 exhaust gas

Claims (17)

In a fuel cell power generation system that generates electricity by electrochemically reacting hydrogen and oxygen,
A fuel storage means for storing an aqueous solution of a water-soluble organic compound;
Electrolysis means for electrolyzing the aqueous solution supplied from the fuel storage means to separate and produce hydrogen and carbon dioxide;
Carbon dioxide recovery means for recovering the carbon dioxide separated and produced by the electrolysis means and supplying the fuel storage means;
Hydrogen recovery means for recovering the hydrogen separated and generated by the electrolysis means;
A fuel cell stack,
Hydrogen supply means for supplying the hydrogen recovered by the hydrogen recovery means to the fuel cell stack;
The hydrogen recovered by the hydrogen recovery means and the carbon dioxide recovered by the carbon dioxide recovery means are supplied, and oxygen contained as a subcomponent in the supplied carbon dioxide reacts with the hydrogen to produce water. Or oxygen reaction means for generating water vapor,
The fuel cell stack performs power generation by causing an electrochemical reaction between the hydrogen and oxygen supplied by the hydrogen supply means. In a fuel cell power generation system that generates electricity by electrochemically reacting hydrogen and oxygen,
Electrolysis means for electrolyzing an aqueous solution of a water-soluble organic compound to separate and produce hydrogen and carbon dioxide;
Carbon dioxide recovery means for recovering the carbon dioxide separated and generated by the electrolysis means;
Carbon dioxide supply means for supplying the carbon dioxide recovered by the carbon dioxide recovery means to a carbon dioxide supply destination;
Hydrogen recovery means for recovering the hydrogen separated and generated by the electrolysis means;
A fuel cell stack,
Hydrogen supply means for supplying the hydrogen recovered by the hydrogen recovery means to the fuel cell stack;
The hydrogen recovered by the hydrogen recovery means and the carbon dioxide recovered by the carbon dioxide recovery means are supplied, and oxygen contained as a subcomponent in the supplied carbon dioxide reacts with the hydrogen to produce water. Or oxygen reaction means for generating water vapor,
The fuel cell stack performs power generation by causing an electrochemical reaction between the hydrogen and oxygen supplied by the hydrogen supply means.   The fuel cell power generation system according to claim 2, further comprising carbon dioxide storage means for storing the carbon dioxide recovered by the carbon dioxide recovery means. The fuel cell power generation system according to any one of claims 1 to 3, further comprising a water recovery unit that recovers the water or water vapor generated by the oxygen reaction unit. The fuel cell power generation system according to any one of claims 1 to 4 , further comprising a hydrogen pressurizing unit that pressurizes the hydrogen recovered by the hydrogen recovery unit. In a fuel cell power generation system that generates electricity by electrochemically reacting hydrogen and oxygen,
A fuel storage means for storing an aqueous solution of a water-soluble organic compound;
Electrolysis means for electrolyzing the aqueous solution supplied from the fuel storage means to separate and produce hydrogen and carbon dioxide;
Carbon dioxide recovery means for recovering the carbon dioxide separated and produced by the electrolysis means and supplying the fuel storage means;
Hydrogen recovery means for recovering the hydrogen separated and generated by the electrolysis means;
A fuel cell stack,
Hydrogen supply means for supplying the hydrogen recovered by the hydrogen recovery means to the fuel cell stack;
Hydrogen purification means for purifying the hydrogen recovered by the hydrogen recovery means ;
Emission gas from the hydrogen purification means and the carbon dioxide recovered by the carbon dioxide recovery means are supplied, and oxygen contained as a subcomponent in the supplied carbon dioxide and discharge from the hydrogen purification means supplied. Oxygen reaction means for reacting the hydrogen contained in the gas to produce water or water vapor;
The a, the fuel cell stack fuel cell power generation system characterized by performing power generation by electrochemical reaction between the hydrogen and oxygen supplied by the hydrogen supply means. In a fuel cell power generation system that generates electricity by electrochemically reacting hydrogen and oxygen,
Electrolysis means for electrolyzing an aqueous solution of a water-soluble organic compound to separate and produce hydrogen and carbon dioxide;
Carbon dioxide recovery means for recovering the carbon dioxide separated and generated by the electrolysis means;
Carbon dioxide supply means for supplying the carbon dioxide recovered by the carbon dioxide recovery means to a carbon dioxide supply destination;
Hydrogen recovery means for recovering the hydrogen separated and generated by the electrolysis means;
A fuel cell stack,
Hydrogen supply means for supplying the hydrogen recovered by the hydrogen recovery means to the fuel cell stack;
Hydrogen purification means for purifying the hydrogen recovered by the hydrogen recovery means;
Emission gas from the hydrogen purification means and the carbon dioxide recovered by the carbon dioxide recovery means are supplied, and oxygen contained as a subcomponent in the supplied carbon dioxide and discharge from the hydrogen purification means supplied. Oxygen reaction means for reacting the hydrogen contained in the gas to produce water or water vapor ;
The a, the fuel cell stack fuel cell power generation system characterized by performing power generation by electrochemical reaction between the hydrogen and oxygen supplied by the hydrogen supply means. The fuel cell power generation system according to claim 7, further comprising carbon dioxide storage means for storing the carbon dioxide recovered by the carbon dioxide recovery means. The fuel cell power generation system according to any one of claims 6 to 8 , further comprising a water recovery unit that recovers the water or water vapor generated by the oxygen reaction unit. The fuel cell power generation system according to any one of claims 6 to 9, further comprising a hydrogen storage unit that stores the hydrogen purified by the hydrogen purification unit. The fuel cell power generation system according to any one of claims 6 to 10, further comprising a hydrogen pressurizing unit that pressurizes the hydrogen purified by the hydrogen purifying unit. The fuel cell power generation system according to claim 5 , further comprising a hydrogen storage unit that stores the hydrogen pressurized by the hydrogen pressurization unit.   The fuel cell power generation system according to any one of claims 1 to 12, further comprising hydrogen storage means for storing the hydrogen recovered by the hydrogen recovery means.   The fuel cell power generation system according to any one of claims 1 to 13, further comprising a carbon dioxide pressurizing unit that pressurizes the carbon dioxide recovered by the carbon dioxide recovery unit.   The fuel cell power generation system according to claim 14, further comprising a carbon dioxide storage unit that stores the carbon dioxide pressurized by the carbon dioxide pressurizing unit.   16. The fuel cell stack according to claim 1, wherein the fuel cell stack is a solid polymer fuel cell stack using a solid polymer electrolyte membrane as an electrolyte, or a phosphoric acid fuel cell stack using phosphoric acid as an electrolyte. The fuel cell power generation system according to claim 1.   The fuel cell power generation system according to any one of claims 1 to 16, wherein the water-soluble organic compound is at least one compound selected from the group consisting of methanol, ethanol, and 2-propanol.

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