JP2016096003A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of simply and efficiently removing a reaction product contained in discharge liquid.SOLUTION: A fuel cell system 2 comprises: a fuel cell 3 to which liquid fuel is supplied; a reflux line 24 for making discharge liquid that is discharged from the fuel cell 3 and contains a reaction product produced by reaction of the liquid fuel reflow to the fuel cell 3; an adjustment tank 25 that is inserted in the reflux line 24 and is for separating the discharge liquid into liquid containing liquid fuel and gas containing the reaction product; a fuel side discharge line 28 for discharging the gas separated by the adjustment tank 25; a separation device 65 that is inserted in the fuel side discharge line 28 and is for separating the reaction product into a solvent from the gas separated by the adjustment tank 25; and a processing device 68 for processing the reaction product separated into the solvent by the separation device 65.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system mounted on a vehicle or the like.

  Conventionally, a fuel cell having an electrolyte layer, an anode disposed on one side of the electrolyte layer, and a cathode disposed on the other side of the electrolyte layer, a fuel supply / discharge portion that supplies liquid fuel to the anode, and air to the cathode There is known a fuel cell system including an air supply / exhaust unit for supplying (see, for example, Patent Document 1).

  The fuel supply / discharge unit in the fuel cell system described in Patent Document 1 includes a reflux pipe that recirculates the liquid fuel discharged from the anode to the anode, a gas-liquid separator interposed in the reflux pipe, and a gas-liquid separator. A gas discharge pipe for discharging the separated nitrogen and water vapor is provided. The air supply / discharge unit includes an air supply path.

  In the fuel supply / exhaust section of the fuel cell system described in Patent Document 1, a closed line that circulates through the reflux pipe, the gas-liquid separator, and the anode is formed, and liquid fuel circulates through the closed line. Further, nitrogen and water vapor separated by the gas-liquid separator are discharged to the outside through the gas discharge pipe. On the other hand, in the air supply / discharge section, the fuel cell normally generates power by supplying air containing oxygen and water vapor to the cathode from the air supply path.

JP2013-134981A

  On the other hand, in such a fuel cell system, fuel is consumed by an electrochemical reaction, an electromotive force is generated, a reaction product is generated, and may be mixed in the effluent.

More specifically, for example, when hydrazine (N ₂ H ₄ ) is consumed as a liquid fuel, nitrogen gas (N ₂ ) and water (H ₂ O) are produced, while production by hydrazine decomposition reaction. As a product (reaction product), ammonia (NH ₃ ) may be generated and mixed in the discharged liquid.

  Since reaction products (such as ammonia) mixed in the effluent may reduce power generation efficiency when the effluent is reused, the reaction products (such as ammonia) are discharged in the fuel cell system. It is required to be separated from the liquid.

  As a method for separating the reaction product (ammonia etc.), for example, it is considered to directly remove the reaction product (ammonia etc.) in the effluent by ion exchange treatment or microbial treatment. However, ion exchange treatment and microbial treatment may not be applied depending on various conditions such as the type of liquid fuel and the type of additive (for example, electrolyte salt).

  On the other hand, for example, it is also considered to separate a reaction product (such as ammonia) in the effluent as a gas and treat it with an adsorbent or a decomposition catalyst. However, when the adsorbent is used, there is a problem that damage is caused by moisture in the fuel cell system, and when a cracking catalyst is used, there is a problem that thermal energy is required for decomposition and costs are increased. .

  Therefore, an object of the present invention is to provide a fuel cell system that can easily and efficiently remove a reaction product contained in an effluent.

  The fuel cell system of the present invention is configured to recirculate a fuel cell to which liquid fuel is supplied and an exhaust liquid containing a reaction product discharged from the fuel cell and generated by a reaction of the liquid fuel to the fuel cell. A gas-liquid separator for separating the discharged liquid into a liquid containing the liquid fuel and a gas containing the reaction product, and the gas-liquid separator. An exhaust path for discharging gas, a separation means for separating the reaction product into a solvent from the gas interposed in the exhaust path and separated in the gas-liquid separator, and the separation means into the solvent And a processing means for processing the separated reaction product.

  In the fuel cell system of the present invention, the reaction product produced by the reaction of the liquid fuel is separated as a gas component by the gas-liquid separator interposed in the reflux path, and then the solvent is separated by the separation means interposed in the exhaust path. In the dissolved state, it is processed in the processing means.

  In such a fuel cell system, since the reaction product is dissolved in the solvent, the ion exchange treatment, the microbial treatment, and the like are hindered compared to the case where the reaction product is dissolved in the liquid fuel (including the additive). The reaction product can be easily processed without any problems.

  Further, in the fuel cell system of the present invention, since it is not necessary to treat the reaction product as a gas, an adsorbent or a decomposition catalyst can be eliminated, and damage and cost increase can be suppressed.

  Therefore, according to the fuel cell system of the present invention, the reaction product contained in the effluent can be easily and efficiently removed.

FIG. 1 is a schematic configuration diagram of an electric vehicle equipped with an embodiment of a fuel cell system of the present invention. FIG. 2 is a schematic configuration diagram of a modified example of the electric vehicle shown in FIG.

1. Overall Configuration of Electric Vehicle As shown in FIG. 1, the electric vehicle 1 is an electric vehicle that drives the motor 42 using the motor 42 as a power source and the fuel cell 3 and the battery 44 as power sources. The electric vehicle 1 is equipped with a fuel cell system 2.

The fuel cell system 2 includes a fuel cell 3, a fuel supply / exhaust unit 4, an air supply / exhaust unit 5, a control unit 6, and a power unit 7.
(1) Fuel Cell The fuel cell 3 is a direct liquid fuel type fuel cell to which liquid fuel containing a fuel component is directly supplied, and is configured as an anion exchange type fuel cell.

  Examples of the fuel component include alcohols such as methanol, ethers such as dimethyl ether, hydrazines such as hydrazine, preferably alcohols and hydrazines, and more preferably hydrazines. .

  As the liquid fuel, the fuel component may be used as it is, but the fuel component can be diluted with a solvent (described later) according to the type of the fuel component, and an electrolyte salt (described later) can be used if necessary. ) Etc. can also be added.

  The fuel cell 3 includes a fuel cell 11. The fuel cell 3 is configured as a stack structure in which a plurality of fuel cells 11 are stacked, but in FIG. 1, only one fuel cell 11 is shown for easy illustration.

  The fuel cell 11 includes a membrane electrode assembly 12, a fuel supply member 13, and an air supply member 14.

  The membrane electrode assembly 12 includes an electrolyte membrane 15 as an example of a solid electrolyte membrane, an anode electrode 16 as an example of a fuel side electrode, and a cathode electrode 17 as an example of an oxygen side electrode.

  The electrolyte membrane 15 is formed of an anion exchange type polymer electrolyte membrane.

  The anode electrode 16 is disposed as a thin layer on the surface of one side in the thickness direction of the electrolyte membrane 15. The anode electrode 16 is formed of, for example, a catalyst carrier that supports a catalyst. The anode electrode 16 can also be formed directly from a catalyst without using a catalyst carrier.

  The cathode electrode 17 is disposed as a thin layer on the opposite side of the anode electrode 16 with respect to the electrolyte membrane 15, that is, on the other surface in the thickness direction of the electrolyte membrane 15. The cathode electrode 17 is formed of, for example, a catalyst carrier that supports a catalyst. The cathode electrode 17 can also be formed directly from a catalyst without using a catalyst carrier.

  The fuel supply member 13 is disposed on one side in the thickness direction of the membrane electrode assembly 12. The fuel supply member 13 is made of a gas impermeable conductive material. A fuel flow path 18 is formed in the fuel supply member 13.

  The fuel flow path 18 is formed on the other surface in the thickness direction of the fuel supply member 13. The fuel flow path 18 is a groove that is recessed from the other surface in the thickness direction of the fuel supply member 13 to one side in the thickness direction, and extends in the vertical direction while being folded back in the width direction (a direction perpendicular to the vertical direction and the thickness direction). It is formed in a twisted shape. The fuel flow path 18 faces the anode electrode 16.

  The air supply member 14 is disposed on the other side in the thickness direction of the membrane electrode assembly 12. The air supply member 14 is formed from a gas impermeable conductive material. An air flow path 19 is formed in the air supply member 14.

The air flow path 19 is formed on one surface in the thickness direction of the air supply member 14. The air channel 19 is a concave groove that is recessed from one surface in the thickness direction to the other in the thickness direction of the air supply member 14, and is formed in a folded shape extending in the vertical direction while being folded back in the width direction. The air flow path 19 faces the cathode electrode 17.
(2) Fuel supply / discharge unit The fuel supply / discharge unit 4 includes a fuel tank 21, a fuel supply line 22, a first pump 23, a first valve 20, a return line 24 as an example of a return path, and an example of a gas-liquid separator. Adjustment tank 25, second pump 26, fuel side exhaust line 28 as an example of an exhaust path, and second valve 60.

  The fuel tank 21 stores the liquid fuel described above. In the fuel tank 21, the liquid fuel is preferably diluted in a solvent corresponding to the type of fuel component.

  Examples of the solvent include, but are not limited to, for example, water when the fuel component is alcohol, and water and / or alcohol (for example, methanol, ethanol, etc.) when the fuel component is hydrazine. , Lower alcohols such as propanol and isopropanol) and the like. These solvents can be used alone or in combination of two or more. The solvent is preferably water.

  The fuel component concentration of the liquid fuel in the fuel tank 21 varies depending on the type of the fuel component, but when the fuel component is hydrazine, for example, it is 1% by mass or more, preferably 5% by mass or more. , 60% by mass or less, preferably 40% by mass or less.

  The liquid fuel preferably contains an electrolyte salt as an additive.

  Examples of the electrolyte salt include alkali metal hydroxides (that is, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide), alkaline earth metal hydroxides (that is, Calcium hydroxide, strontium hydroxide, barium hydroxide, radium hydroxide) and the like. Such electrolyte salts can be used alone or in combination of two or more. The electrolyte salt is preferably an alkali metal hydroxide, and more preferably potassium hydroxide.

  The electrolyte salt concentration of the liquid fuel in the fuel tank 21 is, for example, 0.1 mol / L or more, preferably 0.5 mol / L or more, for example, 5 mol / L or less, preferably 3 mol / L or less, more preferably. 2 mol / L or less.

  The fuel supply line 22 is a pipe for supplying liquid fuel from the fuel tank 21 to an adjustment tank 25 (described later). The supply direction upstream end of the fuel supply line 22 is connected to the fuel tank 21, and the supply direction downstream end is connected to an adjustment tank 25 (described later).

  The first pump 23 is a pump for transporting the liquid fuel in the fuel tank 21 to the fuel flow path 18. The first pump 23 is interposed in the middle of the fuel supply line 22. Examples of the first pump 23 include known liquid feed pumps such as rotary pumps such as rotary pumps and gear pumps, and reciprocating pumps such as piston pumps and diaphragm pumps.

  The first valve 20 is interposed in the middle of the fuel supply line 22, and is specifically disposed on the downstream side in the supply direction of the first pump 23. Examples of the first valve 20 include a known on-off valve such as an electromagnetic valve.

  The reflux line 24 is a reflux pipe for refluxing the liquid fuel to the fuel cell 3. Specifically, the recirculation line 24 supplies water generated by the reaction of the liquid fuel supplied to the fuel flow path 18 of the fuel cell 3 and an exhaust liquid containing a reaction product (such as ammonia) to the fuel cell 3. This is a reflux pipe for returning to the fuel flow path 18. The upstream end (one end) in the return direction of the return line 24 is connected to the downstream end (outlet or upper end) of the fuel flow path 18. The downstream end (other end portion) of the return line 24 in the return direction is connected to the upstream end (inlet or lower end portion) of the fuel flow path 18.

  Thereby, the reflux line 24 and the fuel flow path 18 form a circulation (claude) line through which the liquid fuel circulates.

  The adjustment tank 25 is a tank for temporarily storing the liquid fuel supplied from the fuel tank 21 in a state diluted with an exhaust liquid (described later). The adjustment tank 25 is interposed in the middle of the reflux line 24. A supply direction downstream end of the fuel supply line 22 is connected to the lower end of the adjustment tank 25. The adjustment tank 25 also serves as a gas-liquid separator for separating the liquid discharged from the fuel flow path 18 of the fuel cell 3 into a liquid containing liquid fuel and a gas containing reaction products. .

  In the adjustment tank 25, the liquid fuel is preferably diluted with a solvent corresponding to the type of the fuel component, like the liquid fuel in the fuel tank 21 described above.

  The fuel component concentration of the liquid fuel in the adjustment tank 25 is lower than the fuel component concentration of the liquid fuel in the fuel tank 21. More specifically, the fuel component concentration of the liquid fuel in the adjustment tank 25 is adjusted according to the traveling state of the electric vehicle 1, but when the electric vehicle 1 is traveling at a constant speed, for example, 1 mass% or more, preferably 5 mass% or more, for example, 20 mass% or less, preferably 15 mass% or less.

  Further, like the liquid fuel in the fuel tank 21 described above, the liquid fuel preferably contains an electrolyte salt as an additive.

  The electrolyte salt concentration of the liquid fuel in the adjustment tank 25 is, for example, 0.1 mol / L or more, preferably 0.5 mol / L or more, for example, 5 mol / L or less, preferably 3 mol / L or less, more preferably. 2 mol / L or less.

  The second pump 26 is a pump for transporting (supplying) the liquid fuel in the adjustment tank 25 to the fuel flow path 18. The second pump 26 is disposed in the middle of the reflux line 24, and specifically, is disposed downstream of the adjustment tank 25 in the reflux line 24 in the reflux (supply) direction. Examples of the second pump 26 include a liquid feed pump similar to the first pump 23 described above.

  The fuel side exhaust line 28 is a pipe for exhausting the gas separated in the adjustment tank 25. The upstream end of the fuel side exhaust line 28 in the exhaust direction is connected to the upper end of the adjustment tank 25. The downstream end of the fuel side exhaust line 28 in the exhaust direction is open to the atmosphere.

  The second valve 60 is interposed in the middle of the fuel side exhaust line 28. Examples of the second valve 60 include the same on-off valve as the first valve 20 described above.

  Further, a separation device 65 as an example of a separation means is interposed on the upstream side of the second valve 60 in the fuel side exhaust line 28.

  The separation device 65 is a device for separating a reaction product (such as ammonia) from the gas separated in the adjustment tank 25, and includes a separation tank 66 and a separation pipe 67.

  The separation tank 66 is a tank in which a solvent (described later) for separating reaction products is stored, and a known container is used.

  A solvent is filled around a separation pipe 67 (described later) in the separation tank 66.

  A solvent will not be restrict | limited especially if it is a liquid which can melt | dissolve a reaction product (ammonia etc.), According to the kind of reaction product, it sets suitably. For example, when the reaction product is ammonia, a known aqueous solvent such as water or alcohol can be used. Preferably, water is used.

  The separation pipe 67 penetrates the separation tank 66 and is interposed in the fuel-side exhaust line 28, and is disposed so as to be immersed in the solvent in the separation tank 66.

  Such a separation tube 67 is formed of a material that allows reaction products (such as ammonia) to pass therethrough while blocking other components (such as nitrogen). For example, when the reaction product is ammonia, the separation tube 67 may be a porous tube obtained from a tetrafluoroethylene resin or the like (for example, a poreflon (registered trademark) tube manufactured by Sumitomo Electric Fine Polymer Co., Ltd.) or the like. Can be mentioned. The separation tube 67 may be singular or plural. When there are a plurality of separation tubes 67, the separation tubes 67 may be independent from each other or may be formed in a collective cylinder shape.

  Further, a processing device 68 as an example of processing means is connected to the separation device 65 via a solvent circulation line 69.

  The processing device 68 is a device for processing a reaction product (ammonia or the like) separated (dissolved) in the solvent, and is appropriately designed according to the type of the reaction product. For example, when the reaction product is ammonia, the treatment device 68 includes an ion exchange treatment device using an ion exchange resin that can adsorb and collect ammonia (for example, trade name DIAION SK1B, manufactured by Mitsubishi Chemical Corporation, etc.) For example, a microorganism treatment apparatus capable of decomposing ammonia (for example, a treatment apparatus provided with a trade name BFL5800NT (manufactured by Meito Chemical Co., Ltd.) as a treatment agent) and the like.

  The solvent circulation line 69 is a tube for circulating the solvent between the separation device 65 and the processing device 68, and includes a first circulation line 70, a second circulation line 71, and a third pump 72. Yes.

  The first circulation line 70 is provided on the downstream side of the separation pipe 67 in the gas flow direction (on the right side in FIG. 1) so as to bridge the separation tank 66 and the processing device 68. More specifically, one end (upstream side) of the first circulation line 70 is connected to the separation tank 66, and the other end (downstream side) is connected to the processing device 68.

  The second circulation line 71 is provided on the upstream side of the separation pipe 67 in the gas flow direction (on the left side in FIG. 1) so as to bridge the separation tank 66 and the processing device 68. More specifically, one end (upstream side) of the second circulation line 71 is connected to the processing device 68, and the other (downstream side) end is connected to the separation tank 66.

  Thus, the first circulation line 70 and the second circulation line 71 form a circulation (claude) line through which the solvent circulates between the separation tank 66 and the processing device 68.

  The third pump 72 is a pump for transporting (supplying) the solvent (including the reaction product) in the separation tank 66 to the processing device 68. The third pump 72 is interposed in the middle of the first circulation line 70. As the 3rd pump 72, the liquid feeding pump similar to the above-mentioned 1st pump 23 is mentioned.

By driving the third pump 72, the solvent in the separation tank 66 is supplied to the processing device 68 through the first circulation line 70 and then supplied to the separation tank 66 through the second circulation line 71. That is, the solvent circulates through the separation tank 66, the first circulation line 70, the processing device 68, and the second circulation line 71 in order. In such a case, the solvent flow in the separation tank 66 and the gas flow in the separation pipe 67 are parallel flows.
(3) Air Supply / Discharge Unit The air supply / discharge unit 5 includes an air supply line 33, an air pump 35, a third valve 36, an air discharge line 34, and a fourth valve 37 as an example of an air supply path. ing.

  The air supply line 33 is a pipe for supplying air into the air flow path 19. The upstream end of the air supply line 33 in the supply direction is open to the atmosphere. The downstream end of the air supply line 33 in the supply direction is connected to the upstream end (inlet or upper end) of the air flow path 19.

  The air pump 35 is an air supply pump for transporting air in the atmosphere to the air flow path 19. The air pump 35 is interposed in the air supply line 33. Examples of the air pump 35 include a reciprocating pump such as a piston pump and a diaphragm pump, and a compression pump such as an air compressor.

  The third valve 36 is interposed in the middle of the air supply line 33. Specifically, the third valve 36 is disposed on the downstream side in the supply direction of the air pump 35 in the air supply line 33. Examples of the third valve 36 include the same on-off valve as the first valve 20 described above.

  The air discharge line 34 is a pipe for discharging air from the air flow path 19. The upstream end of the air discharge line 34 in the discharge direction is connected to the downstream end (exit or lower end) of the air flow path 19. The downstream end of the air discharge line 34 in the discharge direction is open to the atmosphere.

The fourth valve 37 is interposed in the middle of the air discharge line 34. Examples of the fourth valve 37 include the same on-off valve as the first valve 20 described above.
(4) Control unit The control unit 6 includes an ECU 41.

The ECU 41 is a control unit (i.e., Electronic Control Unit) that executes electrical control in the electric vehicle 1, and includes a microcomputer that includes a CPU, a ROM, a RAM, and the like. The ECU 41 includes each valve (each of the first valve 20, the second valve 60, the third valve 36, and the fourth valve 37) and each pump (the first pump 23, the second pump 26, the third pump 72, and the air pump 35). Each) and is electrically connected to and controls them.
(5) Power unit The power unit 7 is disposed in a so-called engine room at the front end of the electric vehicle 1. The power unit 7 includes a motor 42, an inverter 43, a battery 44, and a DC / DC converter 45.

  The motor 42 is electrically connected to the fuel cell 3. The motor 42 converts electrical energy output from the fuel cell 3 or the battery 44 into mechanical energy as the driving force of the electric vehicle 1. Examples of the motor 42 include known three-phase motors such as a three-phase induction motor and a three-phase synchronous motor.

  The inverter 43 is electrically connected between the fuel cell 3 and the motor 42 by wiring. The inverter 43 converts the DC power generated by the fuel cell 3 into AC power. Examples of the inverter 43 include a power conversion device in which a known inverter circuit is incorporated.

  The battery 44 is electrically connected to the wiring between the fuel cell 3 and the motor 42. Examples of the battery 44 include known secondary batteries such as nickel metal hydride batteries and lithium ion batteries. The battery 44 can store electric power from the fuel cell 3 and can supply electric power to the motor 42.

The DC / DC converter 45 is electrically connected between the fuel cell 3 and the inverter 43 by wiring. The DC / DC converter 45 is also electrically connected to the ECU 41. Under the control of the ECU 41, the output voltage of the fuel cell 3 is increased or decreased to adjust the power of the fuel cell 3 and the input / output power of the battery 44. .
2. Power Generation Operation Next, power generation in the fuel cell system 2 will be described.

  When the fuel cell system 2 is operating, all valves (the first valve 20, the second valve 60, the third valve 36, and the fourth valve 37) are opened under the control of the ECU 41, and all the pumps (first valve) are operated. The pump 23, the second pump 26, the third pump 72 and the air pump 35) are driven.

  The liquid fuel in the fuel tank 21 is provided with a fuel supply line 22 so as to adjust the fuel component concentration of the liquid fuel in the adjustment tank 25 by adjusting the liquid feed amount of the first pump 23 under the control of the ECU 41. Are supplied to the adjustment tank 25 sequentially.

  The liquid fuel in the adjustment tank 25 is supplied to the fuel flow path 18 of the fuel cell 3 via the reflux line 24 by adjusting the amount of liquid fed by the second pump 26 under the control of the ECU 41.

  The liquid fuel supplied to the fuel flow path 18 flows from the lower side to the upper side in the fuel flow path 18 in contact with the anode electrode 16, and returns to the return line 24 (return (discharge) direction from the fuel cell 3 in the return line 24. It is discharged to the adjustment tank 25 via the downstream part).

  Subsequently, a part of the liquid fuel discharged to the adjustment tank 25 reacts and is consumed in the fuel flow path 18, and the fuel component concentration decreases, so that the liquid fuel is sequentially supplied from the fuel tank 21, and the fuel component After the concentration is adjusted, the liquid fuel is recirculated (supplied) to the fuel flow path 18.

  On the other hand, the air is supplied from the outside of the electric vehicle 1 to the air flow path 19 of the fuel cell 3 through the air supply line 33 while the air volume of the air pump 35 is adjusted by the control of the ECU 41.

  The air supplied to the air flow path 19 flows through the air flow path 19 from the upper side to the lower side while being in contact with the cathode electrode 17, and is discharged to the air discharge line 34.

At this time, in the fuel cell 3, when the fuel component is hydrazine, an electrochemical reaction represented by the following reaction formulas (1) to (3) occurs, and power generation is performed.
(1) N ₂ H ₄ + 4OH ⁻ → N ₂ + 4H ₂ O + 4e ⁻ (reaction at the anode electrode 16)
(2) O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (reaction at the cathode electrode 17)
(3) N ₂ H ₄ + O ₂ → N ₂ + 2H ₂ O (reaction in the entire fuel cell 3)
When the fuel component is methanol, an electrochemical reaction represented by the following reaction formulas (4) to (6) occurs, and power generation is performed.
(4) CH ₃ OH + 6OH ⁻ → CO ₂ + 5H ₂ O + 6e ⁻ (reaction at the anode electrode 16)
(5) O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (reaction at the cathode electrode 17)
(6) CH ₃ OH + 3 / 2O ₂ → CO ₂ + 2H ₂ O (reaction in the entire fuel cell 3)
By these reactions, the fuel component (N ₂ H ₄ or CH ₃ OH) is consumed at the anode electrode 16, oxygen (O ₂ ) and water (H ₂ O) are consumed at the cathode electrode 17, and the anode electrode 16 , Water (H ₂ O) and gas (N ₂ or CO ₂ ) are generated, and an electromotive force (e ⁻ ) is generated. The generated electromotive force is transformed by the DC / DC converter 45, converted into three-phase AC power by the inverter 43, supplied to the motor 42, and converted into mechanical energy for driving the wheels of the electric vehicle 1. Excess electric power that has not been converted into mechanical energy is stored in the battery 44.
3. Separation of reaction products The effluent discharged from the fuel cell 3 via the reflux line 24 to the adjustment tank 25 is composed of the fuel component remaining in the electrochemical reaction, the water produced by the electrochemical reaction, and the water It contains gas components (such as N ₂ and CO ₂ ) that dissolve (dissolve). Further, the discharged liquid may contain a reaction product (by-product) generated by decomposition of the liquid fuel.

More specifically, for example, when hydrazine (N ₂ H ₄ ) is consumed as a liquid fuel, in addition to water generated by an electrochemical reaction and a gas component (nitrogen) dissolved (dissolved) in the water, sometimes as a reaction product, containing ammonia (NH ₃₎ produced by the decomposition of hydrazine _(N 2 _{H 4).}

  Such reaction products (ammonia etc.) mixed in the effluent cause a reduction in power generation efficiency when the effluent is reused, so that it is required to be separated from the effluent.

  Therefore, in the fuel cell system 2, first, in the adjustment tank 25, the discharged liquid is separated into a liquid containing liquid fuel as a main component and a gas containing a reaction product (such as ammonia).

  The temperature of the liquid fuel containing the discharged liquid in the adjustment tank 25 is relatively high, specifically, for example, 40 ° C. or higher, preferably 60 ° C. or higher, and for example, 90 ° C. or lower, preferably 80 ° C. It is as follows.

  In the adjustment tank 25, since the liquid fuel is at the above-described temperature, the above gas contains a reaction product (such as ammonia) in an amount corresponding to the above-described temperature.

  Such gas is supplied to the separation pipe 67 from the adjustment tank 25 via the fuel side exhaust line 28.

  When the gas is supplied to the separation tube 67, only a reaction product (ammonia or the like) that is a component that can be dissolved in the solvent oozes from the membrane surface of the separation tube 67 into the separation tank 66 and is dissolved in the solvent. On the other hand, other components (such as nitrogen) are blocked at the membrane surface of the separation pipe 67 and are not dissolved in the solvent, that is, while remaining in the separation pipe 67, toward the downstream side of the fuel side exhaust line 28. Flow and open to the atmosphere.

  The reaction product (such as ammonia) dissolved in the solvent passes through the first circulation line 70 together with the solvent by the driving of the third pump 72 and is supplied to the processing device 68.

  Then, in the processing device 68, the reaction product (such as ammonia) is processed.

  Specifically, when an ion exchange treatment device is used as the treatment device 68, a reaction product (ammonia or the like) is adsorbed and collected by an ion exchange resin or the like in the ion exchange treatment device. Further, when a microbial treatment apparatus is used as the treatment apparatus 68, a reaction product (ammonia or the like) is decomposed by microorganisms.

By such a process, the reaction product is removed, whereby the solvent supplied to the processing device 68 is purified. The purified solvent is refluxed to the separation tank 66 through the second circulation line 71 by driving the third pump 72 and reused in the separation device 65.
4). In this fuel cell system 2, the reaction product generated by the reaction of the liquid fuel is separated as a gas component by the adjustment tank 25 interposed in the reflux line 24 and then interposed in the fuel side exhaust line 28. It is separated into a solvent by the separation device 65 and processed in the processing device 68 in the dissolved state.

  In such a fuel cell system 2, since the reaction product is dissolved in the solvent, the ion exchange treatment, the microbial treatment, and the like are inhibited as compared with the case where the reaction product is dissolved in the liquid fuel (including the additive). The reaction product can be easily processed without being done.

  Moreover, in this fuel cell system 2, since it is not necessary to process the reaction product as a gas, an adsorbent, a decomposition catalyst, etc. can be made unnecessary, and damage and cost increase can be suppressed.

Therefore, according to this fuel cell system 2, the reaction product contained in the effluent can be easily and efficiently removed.
5. Modification A modification of one embodiment of the present invention will be described with reference to FIG. In this modification, members similar to those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the above-described embodiment, the adjustment tank 25 also serves as a gas-liquid separator.

  On the other hand, in this modification, as shown in FIG. 2, the fuel supply / discharge unit 4 includes a gas-liquid separator 75 in addition to the adjustment tank 25. The fuel side exhaust line 28 is connected not to the adjustment tank 25 but to the gas-liquid separator 75.

  The gas-liquid separator 75 is interposed in the reflux line 24. Specifically, the gas-liquid separator 75 is arranged on the reflux line 24 on the upstream side of the adjustment tank 25 in the reflux direction.

  In the fuel supply / discharge section 4, the liquid fuel discharged from the fuel flow path 18 is discharged as a discharged liquid to the gas-liquid separator 75 via the reflux line 24.

  Subsequently, the liquid fuel from which the gas containing the reaction product (such as ammonia) is separated by the gas-liquid separator 75 is discharged to the adjustment tank 25 through the reflux line 24.

  On the other hand, the gas separated by the gas-liquid separator 75 is supplied to the separation pipe 67 via the fuel side exhaust line 28, and the reaction product (ammonia or the like) is separated and processed in the same manner as described above.

  Also according to this modification, the same operational effects as those of the above-described embodiment can be obtained.

  In the above-described embodiment, the gas from which the reaction product is separated is opened to the atmosphere by the fuel side exhaust line 28. For example, the downstream end of the fuel side exhaust line 28 is connected to the air supply line 33. The gas from which the reaction product is separated can be discharged from the air discharge line 34 together with air by connecting to the middle portion of the air discharge line 34.

2 Fuel Cell System 3 Fuel Cell 24 Reflux Line 25 Adjustment Tank 28 Exhaust Line 65 Separation Device 68 Processing Device

Claims (1)

A fuel cell supplied with liquid fuel;
A recirculation path for recirculating the effluent discharged from the fuel cell and containing a reaction product produced by the reaction of the liquid fuel to the fuel cell;
A gas-liquid separator that is interposed in the reflux path and separates the discharged liquid into a liquid containing liquid fuel and a gas containing reaction products;
An exhaust path for discharging the gas separated in the gas-liquid separator;
A separation means for separating the reaction product into a solvent from the gas interposed in the exhaust path and separated in the gas-liquid separator;
A fuel cell system comprising processing means for processing the reaction product separated in the solvent by the separation means.

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