JP4264875B2 - Condensate drainage system and fuel cell system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for recovering condensed water that has been gas-liquid separated from a water-containing gas, and more particularly to a technique for recovering condensed water that has been gas-liquid separated from a fuel gas supplied to a fuel cell.
[0002]
[Prior art]
FIG. 3 is a system configuration diagram of a conventional fuel cell system. As shown in the figure, the fuel cell system mainly includes a fuel reformer 60 that reforms raw fuel to generate fuel gas, and a fuel cell 77 that generates power by receiving supply of fuel gas and oxidizing gas. A condenser 68 that cools the water vapor component contained in the fuel gas and collects the condensed water, gas-liquid separators 74 and 81 that gas-liquid separate the water contained in the fuel gas, and a collection tank that collects the condensed water 87 and a control unit 90 that performs system control.
[0003]
The fuel reformer 60 evaporates the raw fuel to generate the raw fuel gas, the reformer 62 that reforms the raw fuel gas into a hydrogen-rich fuel gas, and lowers the CO concentration of the fuel gas. The CO reduction part 63 for this is comprised. When steam reforming is performed using methanol as a raw fuel in the reforming unit 62, a methanol decomposition reaction represented by the following formula (1) and a carbon monoxide shift reaction represented by the following formula (2) proceed simultaneously. The reforming reaction shown in the formula (3) occurs.
CH _Three OH → CO + 2H ₂ -90.0 kJ / mol (1)
CO + H ₂ O → CO ₂ + H ₂ +40.5 kJ / mol (2)
CH _Three OH + H ₂ O → CO ₂ + 3H ₂ -49.5 kJ / mol (3)
The reforming reaction of the formula (3) proceeds under a temperature environment of 250 ° C. to 300 ° C., and the fuel gas generated by this reaction contains a large amount of high temperature steam. During operation of the system, the fuel gas flowing down from the fuel reformer 60 through the shutoff valve 64, check valve 65, and flow rate adjustment valve 66 to the gas flow path 67 is heated to around 100 ° C. The temperature is lowered to a temperature range of from 0 to 80 ° C., and condensed water is removed. The condensed water flows from the condenser 68 to the gas-liquid separator 74 through the gas flow path 70 and the shutoff valve 71, and the contained water is removed. After the fuel gas supplied to the anode electrode of the fuel cell 77 through the above path is subjected to a cell reaction, it becomes hydrogen off-gas and flows down through the gas flow path 78 via the flow rate adjustment valve 79 and the check valve 80. In the liquid separator 81, the contained water is further removed.
[0004]
The control unit 90 is a computer system including a CPU 93, a ROM 92, and a RAM 94, and outputs sensor output signals from the liquid level sensors 69, 75, 82 provided in the condenser 68 and the gas-liquid separators 74, 81. When it is detected that the liquid level of the condensed water taken in through the input / output port 95 and stored in the condenser 68 and the gas-liquid separators 74 and 81 has reached a predetermined value, the drain valve 86 is controlled to open and condensing. Condensed water is drained from each of the condenser 68 and the gas-liquid separators 74 and 81 to the recovery tank 87 via the drainage channels 83, 84 and 85. The recovery tank 87 is provided with a relief valve 88 for exhaust, and is configured so that the internal pressure can be adjusted.
[0005]
The oxidizing gas containing oxygen is supplied from the gas flow path 89 to the cathode electrode of the fuel cell 77, subjected to a cell reaction, and then discharged as an oxygen off-gas through the gas flow path 91. Further, an exhaust gas flow path 72 is branched into the gas flow path 70, and when the system is stopped, the shutoff valve 73 is opened while the shutoff valve 71 is closed so that the fuel gas can be exhausted. It is configured as follows.
[0006]
As a technique for recovering condensed water of a fuel cell system, Japanese Patent Laid-Open No. 2001-199702 (Patent Document 1) discloses a condensed water discharge port in a fuel gas path such as a reforming unit, a denaturing unit, a purification unit, and a gas discharging unit. There is proposed a technique for recovering condensed water by purging pressure by injecting an inert gas at the time of starting the system or by dropping the condensed water by its own weight. Japanese Patent Laid-Open No. 62-165870 (Patent Document 2) discloses a waste gas from a gas-liquid separator disposed upstream of the fuel cell and a reserve tank disposed downstream of the fuel cell. A technique to be performed through a pressure loss part has been proposed.
[0007]
[Patent Document 1]
JP 2001-199702 A
[0008]
[Patent Document 2]
Japanese Patent Laid-Open No. 62-165870
[0009]
[Problems to be solved by the invention]
By the way, the fuel gas supplied from the fuel reformer 60 to the fuel cell 77 during system operation is boosted to a constant gas pressure by the flow rate adjusting valve 66, but the process of flowing down the gas flow paths 67, 70, 76, 78. In, the molecular energy gradually decreases and pressure loss occurs due to repeated collisions with air molecules in the pipe, the inner wall of the pipe, or various valve mechanisms. According to the Darcy-Weissbach equation, it is known that the pressure loss is inversely proportional to the inner diameter of the pipe, and is proportional to the square of the average flow velocity in the pipe and the pipe length. Therefore, the pressure loss increases as the pipe lengths of the gas flow paths 67, 70, 76, and 78 are longer and the pipe diameter is smaller. Further, when the condensed water stored in the condenser 68 and the gas-liquid separators 74 and 81 is drained, the gas storage space volume increases, and the gas pressure further decreases. If the gas pressure of the condenser 68 is P1, the gas pressure of the gas-liquid separator 74 is P2, and the gas pressure of the gas-liquid separator 81 is P3, then P1>P2> P3. For this reason, as shown in FIG. 3, when the piping system composed of the drainage channels 83, 84, 85 is merged on the downstream side so that water can be passed between the condenser 68 and the gas-liquid separators 74, 81, Due to the differential pressure, the disadvantage is that the condensed water flows backward to the gas-liquid separators 74 and 81 having a low internal pressure.
[0010]
On the other hand, when the system is stopped, the shutoff valve 71 and the pressure regulating valve 79 are closed, and the shutoff valve 73 is opened to lower the gas pressure of the fuel reformer 60. Therefore, the internal pressure of the condenser 68 is the gas-liquid separator. It falls below the internal pressure of 74, and P2> P1 ≧ P3. Even in this case, there is a problem that the condensed water flows backward to the gas-liquid separator 81 or the condenser 68 having a low internal pressure due to the differential pressure between the condenser 68 and the gas-liquid separators 74 and 81.
[0011]
In order to avoid such inconvenience, it is conceivable to provide a check valve for preventing the backflow of condensed water. However, since the pressure loss further increases, the gas pressure of the entire system does not have to be set correspondingly high. The energy loss will increase.
[0012]
Accordingly, the present invention provides a condensate drainage system that prevents backflow of condensate caused by the differential pressure of each part of the gas flow path of the moisture-containing gas when draining the condensed water gas-liquid separated from the moisture-containing gas. Is an issue. Another object of the present invention is to provide a fuel cell system that prevents backflow of condensed water caused by differential pressure in each part of a gas flow path of fuel gas when draining condensed water separated from fuel gas. To do.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, the condensed water drainage system of the present invention is gas-liquid separated from the gas-liquid separating means disposed at least two or more along the gas flow path of the water-containing gas, and the water-containing gas. A storage means for storing condensed water, a drainage system constituting a drainage path for draining the condensed water from each of the gas-liquid separation means to the storage means, and a valve mechanism disposed in the drainage system And a drainage path from any one of the selected gas-liquid separation means to the storage means. Switch to either water flow or water blocking state A control unit for controlling the valve mechanism. Of the two or more gas-liquid separation means, the gas-liquid separation means arranged upstream of the other gas-liquid separation means is connected to a predetermined gas by a flow rate adjusting valve arranged further upstream thereof. A condenser to which a water-containing gas whose pressure has been increased is supplied, and an exhaust gas passage that branches off from the middle of a gas passage between the condenser and the other gas-liquid separation means; and the exhaust And a shut-off valve disposed in the gas flow path. With this configuration, the drainage path from two or more gas-liquid separation means to the storage means can be performed simultaneously. If it is in the water flow state Since the valve mechanism is controlled so as not to flow, it is possible to prevent the backflow of the condensed water due to the differential pressure between the gas-liquid separation means.
[0014]
Preferably, the control unit controls the valve mechanism so that each of the gas-liquid separation means does not pass water through the drainage system. With such a configuration, the gas-liquid separation means are shielded from each other through the drainage system, so that the reverse flow of the condensed water due to the differential pressure between the gas-liquid separation means can be prevented.
[0015]
Preferably, the control unit is configured such that the gas-liquid separation means disposed on the upstream side of the gas flow path and the gas-liquid separation means disposed on the downstream side of the gas flow path communicate with each other through the drainage system. The valve mechanism is controlled to prevent water. With this configuration, the gas-liquid separating means are shielded from each other through the drainage system, so that the gas-liquid separating means disposed on the upstream side of the gas flow path and the gas-liquid disposed on the downstream side of the gas flow path. The reverse flow of the condensed water caused by the differential pressure between the separating means can be prevented.
[0016]
Preferably, the valve mechanism includes at least one drainage valve disposed for each drainage path from each of the gas-liquid separation means to the storage means, and the control unit is arranged in two or more drainage paths. The valve mechanism is controlled so that all the drain valves provided do not open simultaneously. With this configuration, it is possible to prevent the backflow of the condensed water due to the simultaneous opening of the drain valves disposed in the two or more drain paths.
[0017]
The fuel cell system of the present invention comprises at least two or more gas-liquid separation means disposed along the gas flow path of fuel gas, and a storage means for storing condensed water separated from the fuel gas. A drainage system constituting a drainage path for draining the condensed water from each of the gas-liquid separation means to the storage means, a valve mechanism disposed in the drainage system, and any one selected gas-liquid A drainage path from the separation means to the storage means Switch to either water flow or water blocking state A control unit for controlling the valve mechanism. And Among the two or more gas-liquid separation means, the gas-liquid separation means arranged upstream of the other gas-liquid separation means is adjusted to a predetermined gas pressure by a flow rate adjusting valve arranged further upstream thereof. A condenser to which a pressurized fuel gas is supplied; an exhaust gas flow path that branches off from a middle of a gas flow path between the condenser and the other gas-liquid separation means; and the exhaust gas And a shut-off valve disposed in the flow path. . With this configuration, the drainage path from two or more gas-liquid separation means to the storage means can be performed simultaneously. If it is in the water flow state Since the valve mechanism is controlled so as not to flow, it is possible to prevent the backflow of the condensed water due to the differential pressure between the gas-liquid separation means.
[0018]
Preferably, the control unit controls the valve mechanism so that each of the gas-liquid separation means does not pass water through the drainage system. With such a configuration, the gas-liquid separation means are shielded from each other through the drainage system, so that the reverse flow of the condensed water due to the differential pressure between the gas-liquid separation means can be prevented.
[0019]
Preferably, the control unit is configured such that the gas-liquid separation means disposed on the upstream side of the gas flow path and the gas-liquid separation means disposed on the downstream side of the gas flow path communicate with each other through the drainage system. The valve mechanism is controlled to prevent water. With this configuration, the gas-liquid separating means are shielded from each other through the drainage system, so that the gas-liquid separating means disposed on the upstream side of the gas flow path and the gas-liquid disposed on the downstream side of the gas flow path. The reverse flow of the condensed water caused by the differential pressure between the separating means can be prevented.
[0020]
Preferably, the valve mechanism includes at least one drainage valve disposed for each drainage path from each of the gas-liquid separation means to the storage means, and the control unit is arranged in two or more drainage paths. The valve mechanism is controlled so that all the drain valves provided do not open simultaneously. With this configuration, it is possible to prevent the backflow of the condensed water due to the simultaneous opening of the drain valves disposed in the two or more drain paths.
[0021]
Preferably, the fuel gas is a hydrogen rich gas obtained by steam reforming the raw fuel. Since the steam-reformed fuel gas contains a large amount of high-temperature steam, it is desirable to remove water appropriately before supplying it to the fuel cell, which is suitable for the present invention.
[0022]
Preferably, the gas-liquid separation means is disposed in a gas flow path for supplying fuel gas to a fuel cell from a fuel reformer that generates the fuel gas by steam reforming the raw fuel. Since the fuel gas supplied from the fuel reformer to the fuel cell contains a large amount of high-temperature steam, it is desirable to remove water appropriately before the fuel gas is supplied to the fuel cell, which is suitable for the present invention.
[0023]
Preferably, the gas-liquid separation means is disposed in a gas flow path for hydrogen off-gas discharged from the fuel cell. Since hydrogen off-gas can be reused as combustion fuel for vaporizing raw fuel, it is desirable to perform gas-liquid separation by a gas-liquid separation means, which is suitable for the present invention.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0025]
FIG. 1 is a configuration diagram of a fuel cell system according to the present embodiment. Here, for convenience of explanation, the main part centering on the recovery path of condensed water obtained by gas-liquid separation of water contained in the fuel gas is shown. As shown in the figure, the fuel cell system mainly includes a fuel reformer 10 that reforms raw fuel to generate fuel gas, and a fuel cell 27 that generates power by receiving supply of fuel gas and oxidizing gas. A condenser 18 that cools the water vapor component contained in the fuel gas and collects condensed water, gas-liquid separators 24 and 31 that separate the water contained in the fuel gas into gas and liquid, and a collection tank that stores the condensed water (Reservation tank) 40 and a control unit 43 that executes control processing of the fuel cell system are provided.
[0026]
The fuel reformer 10 is included in the fuel gas, an evaporation unit 11 that vaporizes the raw fuel to generate a raw fuel gas, a reforming unit 12 that reforms the raw fuel gas into a hydrogen-rich fuel gas, and the fuel gas. The CO reduction part 13 which reduces the carbon monoxide which has been comprised is comprised. As the evaporation unit 11, a heat exchange device that exchanges heat between the raw fuel and the heating medium and vaporizes the raw fuel is suitable. As raw fuel, methane (CH _Four ), Ethane (C ₂ H _Five ), Propane (C _Three H ₈ ), Butane (C _Four H _Ten ), Gasoline, light oil, natural gas, methanol (CH _Three OH), ethanol (C ₂ H _Five OH), dimethyl ether (CH _Three OCH _Three ), Acetone (CH _Three C (= O) CH _Three And the like are preferred.
[0027]
Inside the reforming section 12, there are a copper-zinc catalyst (Cu-Zn catalyst), a copper-zinc-chromium catalyst (Cu-Zn-Cr catalyst), a copper-zinc-aluminum catalyst (Cu-Zn). -Al-based catalyst), zinc-chromium-based catalyst (Zn-Cr-based catalyst) and other reforming catalysts are filled, and steam reforming, partial oxidation reforming, or autothermal reforming using these in combination. Since partial oxidation reforming is an exothermic reaction, it is desirable to perform autothermal reforming with excellent load followability after completion of warming up while performing mainly partial oxidation reforming with exothermic reaction during system warm-up. When steam reforming is performed using a mixed solution of methanol and water as a raw fuel, the steam reforming reaction of the above-described formulas (1) to (3) proceeds. When oxygen is introduced into the reforming unit 12, the partial oxidation reforming reaction of the formula (4) proceeds in addition to the steam reforming reaction of the formulas (1) to (3).
CH _Three OH + (1/2) O ₂ → CO ₂ + 2H ₂ + 189.5kJ / mol (4)
The internal temperature of the reforming unit 12 is maintained in a temperature range appropriate for the reforming reaction by a heating action such as an electrocatalyst heater. When methanol reforming is performed, a temperature range of 200 ° C. to 300 ° C. for steam reforming, 400 ° C. to 600 ° C. for partial oxidation reforming, and 200 ° C. to 600 ° C. for autothermal reforming is suitable. The reforming unit 12 that performs the reforming reaction of the raw fuel gas is filled with high-temperature steam, and is supplied to the CO reduction unit 13 together with the fuel gas.
[0028]
The CO reduction unit 13 is filled with a carrier carrying a platinum catalyst, a ruthenium catalyst, a palladium catalyst, a gold catalyst, or an alloy catalyst using these as a first element, which is a selective oxidation catalyst for carbon monoxide. Purified air containing oxygen required for the selective oxidation reaction of carbon monoxide is supplied into the CO reduction unit 13. In order to favorably promote the cell reaction in the fuel cell 77, the carbon monoxide concentration in the fuel gas is preferably about several ppm or less.
[0029]
A condenser 18 and a gas-liquid separator 24 are disposed on gas flow paths 17, 20, and 26 constituting a piping system for supplying fuel gas from the fuel reformer 10 to the fuel cell 27. The condenser 18 is a gas-liquid separation unit that cools and condenses the water vapor component contained in the fuel gas and collects the contained water as condensed water. Since a large amount of high-temperature (for example, around 100 ° C.) water vapor is mixed in the fuel gas supplied from the fuel reforming apparatus 10, the condenser 18 is, for example, a fuel in a cooling pipe in which cooling water is recirculated. A heat exchange type condenser that makes gas contact and cools by a heat exchange type, or a cooling water spray type condenser that cools the fuel gas by spraying cooling water onto the fuel gas and removes saturated water is suitable. is there. The fuel gas is cooled to a low temperature (for example, 60 ° C. to 80 ° C.) in the condenser 18. The condenser 18 is provided with a liquid level sensor 19 for measuring the storage amount (liquid level) of water droplets condensed inside the apparatus. As drive power for the condenser 18, surplus power generated during operation of the fuel cell 27 can be used.
[0030]
The gas flow path 17 is provided with a shut-off valve 14, a check valve 15, and a flow rate adjustment valve 16 from the upstream side to the flow down side. The fuel gas flowing down the gas flow path 17 is predetermined by the flow rate adjustment valve 16. After being increased to the gas pressure, it is supplied to the condenser 18. The valve opening degree of the flow rate adjustment valve 16 is appropriately adjusted in accordance with the required power generation amount of the fuel cell 27. The fuel gas in which most of the contained water portion is condensed by the condenser 18 flows down the gas flow path 20 and is introduced into the gas-liquid separator 24. The gas-liquid separator 24 is a gas-liquid separation means provided to remove moisture contained in the fuel gas to some extent and supply the fuel gas 27 to the fuel cell 27 in a properly humidified state. As the gas-liquid separator 24, for example, a cyclone separator that swirls fuel gas and separates moisture by its centrifugal force is suitable. The gas-liquid separator 24 is provided with a liquid level sensor 25 for measuring the storage amount (liquid level) of water droplets separated in the apparatus.
[0031]
Note that an exhaust gas flow path 22 is branched into the gas flow path 20. When the system is stopped, the shut-off valve 23 is opened to discharge the fuel gas, and the shut-off valve 21 is closed to close the fuel cell 27. The fuel gas supply to the vehicle is stopped.
[0032]
The fuel cell 27 is supplied with hydrogen-rich fuel gas from the gas flow path 26, and the oxidation reaction of the formula (5) occurs in the anode electrode, and the oxidizing gas containing oxygen is supplied from the gas flow path 41 to the cathode electrode. In (6), a reduction reaction occurs. In the fuel cell 27 as a whole, an electromotive reaction of the formula (7) occurs. As the fuel cell 27, a solid polymer electrolyte type fuel cell is suitable. The polymer electrolyte fuel cell has the advantages of being able to start at room temperature, so the start-up time is short, high current density is obtained at room temperature, low-load operation is possible, and the size and weight can be reduced. It has excellent characteristics as a battery. In a high load state, the current density flowing through the polymer electrolyte membrane is increased, and the polymer electrolyte membrane is dried due to the electroosmosis phenomenon. Therefore, it is desirable that the fuel gas and the oxidizing gas are appropriately humidified.
H ₂ → 2H ⁺ + 2e ^- ... (5)
(1/2) O ₂ + 2H ⁺ + 2e ^- → H ₂ O ... (6)
H ₂ + (1/2) O ₂ → H ₂ O ... (7)
The fuel gas subjected to the electromotive reaction is discharged as hydrogen off-gas from the fuel cell 27 via the gas flow path 28, while the oxidizing gas subjected to the electromotive reaction is converted from the fuel cell 27 to the oxygen off-gas. It is discharged via the flow path 42. A flow rate adjustment valve 29, a check valve 30, and a gas-liquid separator 31 are disposed in the gas flow path 28 from the upstream side to the downstream side. Since the hydrogen off-gas discharged from the fuel cell 27 contains moisture, the gas-liquid separator 31 performs gas-liquid separation. The gas / liquid separator 31 is a gas / liquid separator having the same function as the gas / liquid separator 24. The gas-liquid separator 31 is provided with a liquid level sensor 32 for measuring the storage amount (liquid level) of water droplets separated into gas and liquid inside the apparatus. The hydrogen off-gas discharged from the gas-liquid separator 31 is reused in the aforementioned evaporation unit 11 to generate combustion gas (heating medium) for heating the raw fuel (heated medium). The condensed water that has been gas-liquid separated in each of the above-described condenser 18 and gas-liquid separators 24 and 31 is drained to a recovery tank 40 that functions as a condensed water storage means. Since the condensed water collected in the recovery tank 40 contains many impurities such as hydrofluoric acid and sulfuric acid due to elution and decomposition of the polymer electrolyte membrane, the impurities are removed by a filtration membrane such as an ion exchange resin. And used as reformed water for steam reforming.
[0033]
A drainage valve 36 that drains condensed water stored in the condenser 18 is disposed in the drainage path 33 that constitutes a drainage path between the condenser 18 and the recovery tank 40. Similarly, a drainage valve 37 is disposed in the drainage path 34 constituting the drainage path between the gas-liquid separator 24 and the recovery tank 40, and the drainage path between the gas-liquid separator 31 and the recovery tank 40 is provided. A drainage valve 38 is disposed in the drainage channel 35 that is configured. A drainage system of condensed water in the fuel cell system is constructed by the above-described drainage channels 33, 34, and 35. The recovery tank 40 is provided with a relief valve 39 for exhaust, and is configured so that the internal pressure can be adjusted.
[0034]
The control unit 43 for controlling the fuel cell system is configured as a computer system centered on a microcomputer and stores various programs (including a drain valve control processing routine described later) and various data necessary for system control. A ROM 44, a CPU 45 that reads and executes a program written in the ROM 44, a RAM 46 that functions as a work memory for the CPU 45, and the sensor output signals of the liquid level sensors 19, 25, and 32 described above, and a drain valve 36, 37, 38, and shut-off valves 14, 21, 23, and an input / output port 47 for outputting various control signals for controlling the opening and closing of the flow rate adjusting valves 16, 29. A system start / stop signal is input to the control unit 24 from a host controller (not shown).
[0035]
In this specification, “gas-liquid separation means” means means for gas-liquid separation of moisture from moisture-containing gas, and includes the above-described condenser 18 and gas-liquid separators 24, 31. In the present embodiment, the fuel gas is exemplified as the moisture-containing gas, but an oxidizing gas or other gas may be used. The “reservoir means” refers to a means for storing condensed water that has been gas-liquid separated from the moisture-containing gas, and includes the above-described recovery tank 40. The storage means is not limited to one, and there may be two or more. The “drainage path” refers to a path for draining condensed water from each gas-liquid separation means to the storage means, and includes one or more drainage paths. The “drainage” is not limited to a dedicated drainage path for a specific gas-liquid separation means, and may share part of the drainage paths for two or more gas-liquid separation means. In other words, two or more drainage paths may join in the middle of the path. In the case where the two or more drainage paths have a merging part that merges in the middle of the path, the valve mechanism is provided between the gas-liquid separation means and the merging part. In other words, in the present invention, at least one or more drainage valves are arranged in a path from any gas-liquid separation means to another gas-liquid separation means, and two or more gas-liquid separations upstream from the junction. The means are configured not to pass water to each other. The number of drainage paths from a single gas-liquid separation means to a single storage means is not limited to one, and may be two or more. The “drainage system” is a general term for all drainage paths. “Valve mechanism” is a collective term for two or more drainage valves installed in the drainage system. Through the opening and closing control of the drainage valve, the water passage state and the water shielding state of the drainage channel are switched to each other to separate the gas and liquid. It is means for controlling establishment (water flow), shut-off (water shielding), and change of the drainage path from the means to the storage means, and includes a switching valve described later in addition to the drainage valves 36, 37, and 38 described above. The number of drainage valves provided on the drainage path from the gas-liquid separation means to the storage means is not limited to one, and may be two or more.
[0036]
FIG. 2 is a flowchart describing a drain valve control processing routine for draining the condensed water gas-liquid separated from the fuel gas to the recovery tank 40. The control unit 43 repeatedly executes event processing of this routine that occurs at a predetermined interval in the main control program. When shifting to this routine, the control unit 43 first checks whether or not a system stop signal has been received from the host controller (step S1). When the system stop signal is not received (step S1; NO), the sensor output signal of the liquid level sensor 19 is checked, and whether or not the liquid level of the condensed water stored in the condenser 18 exceeds the threshold value. Is determined (step S2). When the liquid level of the condensed water exceeds the threshold value (step S2; YES), the drain valve 36 is opened, and the drain path (drain path 33) of the condenser 18 is passed through, while the drain valve 37 , 38 are closed, and the drainage channels (drainage channels 34, 35) of the gas-liquid separators 24, 31 are shut off (step S3). In this way, by controlling the opening and closing of the drainage valves 36, 37, and 38 of the drainage system so that the condenser 18 and the gas-liquid separators 24 and 31 do not pass between each other, the gas-liquid separator 24, which has a low internal pressure, Thus, the condensate water can be prevented from flowing back to 31 and drained from the condenser 18 to the recovery tank 40. The control unit 43 maintains this state for T1 seconds (step S4), drains most of the condensed water stored in the condenser 18 into the recovery tank 40, and then returns to step S1.
[0037]
Here, in step S2, if the control unit 43 determines that the liquid level of the condensed water stored in the condenser 18 does not exceed the threshold value (step S2; NO), the drain valve 36 is closed and the condenser 18 is closed. The drainage route (drainage channel 33) is blocked (step S6). Next, the sensor output signal of the liquid level sensor 25 is checked, and it is determined whether or not the liquid level of the condensed water stored in the gas-liquid separator 24 exceeds the threshold value (step S7). When the liquid level of the condensed water exceeds the threshold value (step S7; YES), the drain valve 37 is opened, and the drainage path (drainage path 34) of the gas-liquid separator 24 is made to flow, while draining. The valve 38 is closed, and the drainage path (drainage path 35) of the gas-liquid separator 31 is shut off (step S8). The controller 43 maintains this state for T2 seconds (step S9), drains most of the condensed water stored in the gas-liquid separator 24 into the recovery tank 40, and then returns to step S1.
[0038]
In step S7, when the control unit 43 determines that the liquid level of the condensed water stored in the gas-liquid separator 24 does not exceed the threshold (step S7; NO), the drain valves 36 and 37 are closed, The drainage path (drainage paths 33 and 34) of the condenser 18 and the gas-liquid separator 24 is shut off (step S10). Next, the sensor output signal of the liquid level sensor 32 is checked, and it is determined whether or not the liquid level of the condensed water stored in the gas-liquid separator 31 exceeds a threshold value (step S11). When the liquid level of the condensed water exceeds the threshold value (step S11; YES), the drain valve 38 is opened, and the drainage path (drainage path 35) of the gas-liquid separator 31 is made to flow (step S12). ). The controller 43 maintains this state for T3 seconds (step S13), drains most of the condensed water stored in the gas-liquid separator 31 to the recovery tank 40, and then returns to step S1.
[0039]
On the other hand, when the controller 43 determines in step S11 that the liquid level of the condensed water stored in the gas-liquid separator 31 does not exceed the threshold value (step S11; NO), the drain valve 38 is closed (step S14). ), Recursively return to step S1. In step S1, when the control unit 43 receives a system stop signal from the host controller (step S1; YES), the control valve 43 opens the shutoff valve 23 and exhausts the fuel gas from the gas flow path 22, while the shutoff valve 21 is turned off. The valve is closed and the supply of the fuel gas to the fuel cell 27 is stopped (step S5). When the control unit 43 finishes the processing step of step S5, the control unit 43 sequentially executes the processing steps after step S6.
[0040]
As described above, according to the present embodiment, when the condensed water is collected in the collection tank 40, the valve mechanism is controlled so that two or more drain valves 36, 37, 38 are not opened at the same time. The condenser 18 and the gas-liquid separators 24 and 31 do not pass through each other through the drainage system, and the backflow of the condensed water due to the differential pressure between the condenser 18 and the gas-liquid separators 24 and 31 can be prevented. . Moreover, since a check valve is not used, the backflow of condensed water can be prevented while reducing the energy loss of the entire system.
[0041]
The present invention is not limited to the above-described configuration. For example, three input ports communicating with each of the drainage paths of the condenser 18 and the gas-liquid separators 24 and 31 and one communicating with the recovery tank 40 are provided. A switching valve having an output port is provided in the drainage system, and the input port to be communicated with the output port is controlled so that the condenser 18 and the gas-liquid separators 24 and 31 do not pass through the drainage system. It is also possible to control so that the recovery tank 40 is drained. Of course, the drainage valve and the above-described switching valve may be appropriately combined and disposed in the drainage system. The present invention is not limited to a fuel cell system, and can be applied to any condensate drainage system having a mechanism for draining condensed water obtained by gas-liquid separation of a water-containing gas to a storage means.
[0042]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, when draining condensed water from a gas-liquid separation means to a storage means, the back flow of condensed water resulting from the differential pressure | voltage between gas-liquid separation means can be prevented.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fuel cell system according to an embodiment.
FIG. 2 is a flowchart describing a drain valve control processing routine of the present embodiment.
FIG. 3 is a configuration diagram of a conventional fuel cell system.
[Explanation of symbols]
10 ... Fuel reformer
17, 20, 26, 28 ... gas flow path
18 ... Condenser
24, 31 ... Gas-liquid separator
33, 34, 35 ... drainage channel
36, 37, 38 ... drain valve
40 ... Recovery tank
43 ... Control unit

Claims (11)

Gas-liquid separation means disposed at least two or more along the gas flow path of the moisture-containing gas;
Storage means for storing condensed water gas-liquid separated from the moisture-containing gas;
A drainage system that constitutes a drainage path for draining the condensed water from each of the gas-liquid separation means to the storage means;
A valve mechanism disposed in the drainage system;
A control unit that controls the valve mechanism to switch the drainage path from any one of the selected gas-liquid separation means to the storage means to either a water-permeable state or a water-impervious state ,
Among the two or more gas-liquid separation means, the gas-liquid separation means arranged upstream of the other gas-liquid separation means is adjusted to a predetermined gas pressure by a flow rate adjusting valve arranged further upstream thereof. A condenser supplied with pressurized moisture-containing gas ,
Condensation provided with an exhaust gas passage that branches off from the middle of the gas passage between the condenser and the other gas-liquid separation means, and a shutoff valve disposed in the exhaust gas passage Water drainage system. 2. The condensed water drainage system according to claim 1, wherein the control unit controls the valve mechanism so that each of the gas-liquid separation means does not pass water through the drainage system. The control unit prevents the gas-liquid separation means disposed on the upstream side of the gas flow path and the gas-liquid separation means disposed on the downstream side of the gas flow path from passing each other through the drainage system. The condensed water drainage system according to claim 2, wherein the valve mechanism is controlled. The valve mechanism includes a drain valve disposed at least one for each drain path from each of the gas-liquid separation means to the storage means,
The condensed water drainage according to any one of claims 1 to 3, wherein the control unit controls the valve mechanism so that all drainage valves disposed in two or more drainage paths do not open simultaneously. system. Gas-liquid separation means disposed at least two or more along the gas flow path of the fuel gas;
Storage means for storing condensed water gas-liquid separated from the fuel gas;
A drainage system that constitutes a drainage path for draining the condensed water from each of the gas-liquid separation means to the storage means;
A valve mechanism disposed in the drainage system;
A control unit that controls the valve mechanism to switch the drainage path from any one of the selected gas-liquid separation means to the storage means to either a water-permeable state or a water-impervious state ,
Among the two or more gas-liquid separation means, the gas-liquid separation means arranged upstream of the other gas-liquid separation means is adjusted to a predetermined gas pressure by a flow rate adjusting valve arranged further upstream thereof. A condenser to which pressurized fuel gas is supplied;
A fuel comprising: an exhaust gas passage that branches off from the middle of the gas passage between the condenser and the other gas-liquid separation means; and a shut-off valve disposed in the exhaust gas passage. Battery system. The fuel cell system according to claim 5, wherein the control unit controls the valve mechanism so that each of the gas-liquid separation means does not pass water through the drainage system. The control unit prevents the gas-liquid separation means disposed on the upstream side of the gas flow path and the gas-liquid separation means disposed on the downstream side of the gas flow path from passing each other through the drainage system. The fuel cell system according to claim 6, wherein the valve mechanism is controlled. The valve mechanism includes a drain valve disposed at least one for each drain path from each of the gas-liquid separation means to the storage means,
The fuel cell according to any one of claims 5 to 7, wherein the control unit controls the valve mechanism so that all drain valves arranged in two or more drain paths do not open simultaneously. system. The fuel cell system according to any one of claims 5 to 8, wherein the fuel gas is a hydrogen-rich gas obtained by steam reforming a raw fuel. The gas-liquid separation means is disposed in a gas flow path for supplying fuel gas to a fuel cell from a fuel reformer that generates the fuel gas by steam reforming the raw fuel. Fuel cell system. The fuel cell system according to claim 10, wherein the gas-liquid separation means is disposed in a gas flow path of hydrogen off-gas discharged from the fuel cell.

Images