JP2019040762A - Fuel cell system - Google Patents

Abstract

To attain cost reduction of a fuel cell system configured to recycle a part of a modified gas which is modified by a modification part.SOLUTION: In a fuel cell system 1, a first boundary surface Sk1 between a modified gas and mixed water resulting from mixing drain water and condensed water is positioned from a first portion 40a that is a bottom part to a portion closer to a drain water introduction port 40c in a channel of a mixed water pipe 40 which is formed in a U shape of which the upper side is opened, and leads out the mixed water. A second boundary surface Sk2 that is a boundary surface between the mixed water and atmospheric air, is positioned in a portion at least closer to a condensed water introduction port 40b than the first portion 40a in the channel of the mixed water pipe 40 and communicates with the first boundary surface Sk1 via the mixed water. The fuel cell system is provided in such a manner that heights of the first boundary surface and the second boundary surface in a vertical direction become equal to or higher than a predetermined height Hs at which outflow of the modified gas from the first boundary surface Sk1 to the first portion 40a is regulated in a case where the first boundary surface Sk1 is located at a first position P1 which is a lower limit position where the modified gas does not flow out of the first boundary surface Sk1 to the first portion 40a.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell system.

  As one type of fuel cell system, one shown in Patent Document 1 is known. As shown in FIG. 1 of Patent Document 1, the fuel cell system includes a desulfurizer 22 for removing sulfur components in the reforming raw material supplied through the reforming raw material supply flow path 14, and desulfurization. A reformer 4 for reforming the reformed raw material, and a fuel cell stack 6 for generating electric power by oxidation and reduction of the reforming raw material and the oxidizing agent.

  In this fuel cell system, since the desulfurization reaction of the reforming raw material by the desulfurizer 22 is performed under conditions containing hydrogen, a part of the reformed gas that is the reforming raw material reformed by the reformer 4 is used. A recycling channel 48 for returning to the desulfurizer 22 is provided. A liquid drainer 60 is disposed in the recycle channel 48. The liquid drainer 60 is a steam trap that keeps moisture (drain water) in the reformed gas condensed by cooling the reformed gas. The drain water is discharged from the liquid drainer 60 to the outside through a drainage channel (not shown).

JP 2011-159485 A

  In the fuel cell system described in Patent Document 1 described above, in addition to the liquid drainer 60, the reformed gas flowing through the recycle channel 48 is discharged into the drainage flow in consideration of the failure of the liquid drainer 60. For example, a water seal structure such as a U-shaped tube may be provided so as not to be discharged to the outside through the path. By configuring the steam trap in this way, adding a U-shaped tube or the like increases the cost of the fuel cell system because the number of parts is relatively large. On the other hand, in the fuel cell system, there is a demand for cost reduction in order to improve the diffusion rate.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce the cost of a fuel cell system that recycles part of the reformed gas reformed in the reforming section.

  In order to solve the above-described problem, a fuel cell system according to claim 1 includes a fuel cell that generates electric power using a reformed gas containing hydrogen and an oxidant gas, an evaporation unit that generates water vapor from the reformed water, and a reformer. The reforming unit generates reformed gas from the raw material and steam, supplies the reformed gas to the fuel cell, the sulfur component contained in the reforming material is removed by hydrogen, and the reforming material is modified. A desulfurizer that supplies the reformer, a reformed gas supply pipe that supplies reformed gas from the reformer to the fuel cell, and a reforming raw material supply pipe that supplies the reforming raw material to the desulfurizer, A recycle gas pipe that returns a part of the reformed gas to the desulfurizer as a recycle fuel. The recycle gas pipe that generates drain water and the exhaust gas containing water vapor from the fuel cell are condensed to produce condensed water and condensed. With a gas outlet for discharging the exhaust gas And a condensate inlet for introducing condensed water from the condenser, and a second end for drain water from the recycle gas pipe. A drain water introduction port for introducing water, and disposed between the bottom portion and the condensed water introduction port and below the drain water introduction port, and a mixed water outlet for deriving mixed water in which the drain water and condensed water are mixed Is disposed above the first portion which is the flow path at the bottom of the mixed water pipe, stores the reformed water, and discharges the reformed water below the drain water inlet. A water tank having a water discharge port and a water tank disposed above the first part and below the drain water introduction port, the mixed water led out from the mixed water lead-out port is led to the water tank as reformed water, and the mixed water is A water purification unit to purify And a reformed water outlet pipe, which is a boundary surface between the reformed gas and the mixed water, located from the first part to the drain water inlet side in the flow path of the mixed water pipe. A boundary surface between the mixed water and the atmosphere, which is located at a portion closer to the condensed water inlet than the first portion in the flow path of the mixed water pipe and communicated via the first boundary surface and the mixed water. The height along the vertical direction with respect to the second boundary surface is that the reformed gas having a predetermined pressure acts on the first boundary surface, so that the reformed gas is transferred from the first boundary surface to the first portion. When the first boundary surface is located at the first position, which is the lower limit position where it does not flow out, the reforming from the first boundary surface to the first site is performed by the mixed water between the first boundary surface and the second boundary surface. The mixed water pipe and the reforming water outlet pipe are connected so that the gas outflow is higher than the prescribed height. And a water tank.

  According to this, the height along the up-and-down direction of the 1st boundary surface located in the 1st position and the 2nd boundary surface connected to the 1st boundary surface via mixed water will become more than predetermined height. As described above, a mixed water pipe, a reforming water outlet pipe, and a water tank are provided. For this reason, the mixed water between the first boundary surface and the second boundary surface suppresses the outflow of the reformed gas from the first boundary surface to the first region, the second boundary surface, and the outside. Therefore, a water sealing member such as a steam trap and a U-shaped tube as in the conventional technique is not necessary, and the number of parts of the fuel cell system can be reduced. Therefore, the cost of the fuel cell system can be reduced.

It is the schematic which shows the outline | summary of 1st embodiment of the fuel cell system by this invention. FIG. 2 is a cross-sectional view of a mixed water pipe, a recycle gas pipe, a reformed water outlet pipe, and a water tank of the fuel cell system shown in FIG. 1, showing a state where a first boundary surface is located at a first position. It is a block diagram of the fuel cell system shown in FIG. FIG. 3 is a cross-sectional view of the mixed water pipe and the like of the fuel cell system shown in FIG. 2, and the first boundary surface is located from the first part in the flow path of the mixed water pipe to the part on the drain water inlet side during power generation operation of the fuel cell system. It represents the state to do. It is sectional drawing, such as a mixing water pipe, which shows the 1st modification of 1st embodiment of the fuel cell system by this invention. It is sectional drawing, such as a mixing water pipe, which shows the 2nd modification of 1st embodiment of the fuel cell system by this invention. It is sectional drawing, such as a mixing water pipe, which shows the 3rd modification of 1st embodiment of the fuel cell system by this invention. It is sectional drawing, such as a mixing water pipe, which shows 2nd embodiment of the fuel cell system by this invention. It is sectional drawing, such as a mixing water pipe, which shows the 1st modification of 2nd embodiment of the fuel cell system by this invention. It is sectional drawing, such as a mixing water pipe, which shows the 2nd modification of 2nd embodiment of the fuel cell system by this invention. It is a block diagram of the 2nd modification of 2nd embodiment of the fuel cell system by this invention.

<First embodiment>
Hereinafter, a first embodiment of a fuel cell system according to the present invention will be described. In this specification, for convenience of explanation, the upper side and the lower side in FIG. 1 will be described as the upper and lower sides of the fuel cell system 1, respectively, and the left side and the right side will be described as the left side and the right side of the fuel cell system 1, respectively.

  The fuel cell system 1 includes a power generation unit 10 and a hot water tank 21 as shown in FIG. The power generation unit 10 includes a housing 10a, a fuel cell module 11, a condenser 12, an inverter device 13, a water tank 14 for storing reformed water, and a control device 15.

  As shown in FIG. 1, the fuel cell module 11 (30) includes a casing 31, an evaporation unit 32, a reforming unit 33, and a fuel cell 34. The casing 31 is formed in a box shape with a heat insulating material.

  The reforming material is supplied from the supply source Gs to the evaporation unit 32 via the reforming material supply pipe 11a. The supply source Gs is, for example, a gas supply pipe for city gas or a gas cylinder for LP gas. The reforming raw materials include gas fuels for reforming such as natural gas and LP gas, and liquid fuels for reforming such as kerosene, gasoline, and methanol. In this embodiment, natural gas will be described.

  Further, the reforming water is supplied to the evaporation unit 32 from the water tank 14 through the water supply pipe 11b. The water supply pipe 11b is provided with a reforming water pump 11b1 that sends out reforming water. The reforming water pump 11b1 adjusts the flow rate of reforming water (flow rate per unit time) according to the control command value from the control device 15.

  The evaporation unit 32 generates water vapor from the reformed water. Specifically, the evaporating unit 32 is heated by a combustion gas described later, and evaporates the reformed water supplied from the water tank 14 to generate water vapor. Further, the evaporation unit 32 preheats the reforming material supplied from the supply source Gs. The evaporation unit 32 mixes the steam generated in this way with the preheated reforming raw material and supplies the mixture to the reforming unit 33.

  The reforming unit 33 generates reformed gas from the reforming raw material and steam, and supplies the reformed gas to the fuel cell 34. Specifically, the reforming unit 33 is heated by a combustion gas, which will be described later, and supplied with heat necessary for the steam reforming reaction, so that the mixed gas (reforming raw material, water vapor) supplied from the evaporation unit 32 is supplied. ) To generate and derive the reformed gas. The reforming unit 33 is filled with a catalyst (for example, Ru or Ni-based catalyst), and the mixed gas reacts with the catalyst to be reformed to generate a gas containing hydrogen gas and carbon monoxide. (So-called steam reforming reaction).

  The reformed gas contains hydrogen, carbon monoxide, carbon dioxide, steam, unreformed natural gas (methane gas), and reformed water (steam) that has not been used for reforming. The steam reforming reaction is an endothermic reaction.

  The fuel cell 34 generates power using a reformed gas containing hydrogen and an oxidant gas. The fuel cell 34 is configured by laminating a fuel electrode, an air electrode (oxidant electrode), and a plurality of cells 34a made of an electrolyte interposed between the two electrodes. The fuel cell of this embodiment is a solid oxide fuel cell, and uses zirconium oxide, which is a kind of solid oxide, as an electrolyte. Hydrogen, carbon monoxide, methane gas, etc. are supplied to the fuel electrode of the fuel cell 34 as fuel.

  On the fuel electrode side of the cell 34a, a fuel flow path 34b through which the reformed gas as the fuel flows is formed. An air flow path 34c through which air (cathode air) that is an oxidant gas flows is formed on the air electrode side of the cell 34a.

  The fuel cell 34 is provided on the manifold 35. The reformed gas from the reforming unit 33 is supplied to the manifold 35 via the reformed gas supply pipe 38. The lower end (one end) of the fuel flow path 34b is connected to a fuel outlet (not shown) of the manifold 35, and the reformed gas led out from the fuel outlet is introduced from the lower end and led out from the upper end.

  Cathode air is supplied from the cathode air blower 11c1 through the cathode air supply pipe 11c, introduced from the lower end of the air flow path 34c, and led out from the upper end. The cathode air blower 11c1 sends the air in the housing 10a as cathode air.

  A combustion unit 36 is provided between the fuel cell 34 and the evaporation unit 32 and the reforming unit 33. The combustion unit 36 heats the reforming unit 33 by burning the anode offgas (fuel offgas) from the fuel cell 34 and the cathode offgas (oxidant offgas) from the fuel cell 34.

  In the combustion unit 36, the anode off gas is burned and a flame 37 is generated. In the combustion section 36, the anode off-gas is burned and the combustion exhaust gas (corresponding to the exhaust gas of the present invention) is generated. Further, the combustion unit 36 sets the temperature in the fuel cell module 30 to the operating temperature of the fuel cell 34.

  The condenser 12 condenses the combustion exhaust gas containing water vapor from the fuel cell 34 to generate condensed water, and has a gas discharge port 12a for discharging the condensed combustion exhaust gas. Specifically, the condenser 12 is a heat exchanger in which combustion exhaust gas exhausted from the fuel cell module 30 is supplied and hot water stored in the hot water storage tank 21 is supplied, and heat is exchanged between the combustion exhaust gas and the hot water storage. is there. The gas discharge port 12 a is provided on the side wall of the condenser 12.

  The hot water storage tank 21 stores hot water, and is connected to a hot water circulation line 22 through which the hot water circulates (circulates in the direction of the arrow in the figure). On the hot water circulation line 22, a hot water circulation pump 22 a and the condenser 12 are arranged in order from the lower end to the upper end of the hot water tank 21.

  In the condenser 12, the combustion exhaust gas from the fuel cell module 30 is introduced into the condenser 12 through the first exhaust pipe 11 d, heat exchange is performed with the hot water storage, and cooling is performed. Water vapor is condensed. The combustion exhaust gas after cooling is discharged to the outside through the gas exhaust port 12a and the second exhaust pipe 11e connected to the gas exhaust port 12a. On the other hand, the condensed condensed water is led out to the mixed water pipe 40 (details will be described later).

  An exhaust heat recovery system 20 is configured from the condenser 12, the hot water tank 21, and the hot water circulation line 22 described above. The exhaust heat recovery system 20 recovers and stores the exhaust heat of the fuel cell module 30 in hot water storage.

  The inverter device 13 receives the DC voltage output from the fuel cell 34, converts it to a predetermined AC voltage, and supplies it to a power line 16b connected to an AC system power supply 16a and an external power load 16c (for example, an electrical appliance). Output.

  The inverter device 13 receives an AC voltage from the system power supply 16a via the power supply line 16b, converts it to a predetermined DC voltage, and outputs it to an auxiliary machine (each pump, blower, etc.) or the control device 15. The control device 15 controls the operation of the fuel cell system 1 by driving an auxiliary machine.

  Next, the reforming material supply pipe 11a will be described in detail. The reforming raw material supply pipe 11a is provided with a shut-off valve 11a1, a pressure sensor 11a2, a flow rate sensor 11a3, a pressure regulator 11a4, a raw material pump 11a5, and a desulfurizer 11a6 in order from the upstream.

  The shutoff valve 11a1 can shut off the supply of the reforming raw material. The shutoff valve 11a1 is a valve (double valve) that shuts off the reforming raw material supply pipe 11a in an openable / closable manner according to a command from the control device 15. The pressure sensor 11a2 detects the pressure of the reforming raw material (pressure at the installation location of the pressure sensor 11a2). The detection result of the pressure sensor 11a2 is output to the control device 15. The flow rate sensor 11a3 detects the flow rate (flow rate per unit time) of the reforming raw material. The detection result of the flow sensor 11a3 is output to the control device 15.

  The pressure adjusting device 11a4 adjusts the input pressure of the reforming raw material to a predetermined pressure and outputs it. For example, the pressure adjusting device 11a4 is a zero governor that outputs the input pressure of the reforming raw material at atmospheric pressure. The pressure adjusting device 11a4 is for lowering the pressure with respect to the recycle gas pipe 39, which will be described later, on the primary side of the raw material pump 11a5 of the reforming raw material supply pipe 11a. The pressure adjusting device 11 a 4 causes the reforming material supply pipe 11 a to have a lower pressure than the recycle gas pipe 39, so that the reformed gas flows through the recycle gas pipe 39.

  The raw material pump 11a5 delivers the raw material for reforming. The raw material pump 11 a 5 adjusts the flow rate of the reforming raw material (flow rate per unit time) according to the control command value from the control device 15.

  The desulfurizer 11a6 removes a sulfur component (for example, a sulfur compound) contained in the reforming raw material with hydrogen and supplies the reforming raw material to the reforming unit 33. In the desulfurizer 11a6, a catalyst and a super high-order desulfurizing agent are accommodated. In the catalyst, a sulfur compound and hydrogen react to generate hydrogen sulfide. For example, the catalyst is nickel-molybdenum or cobalt-molybdenum. As the ultra-high order desulfurizing agent, for example, a copper-zinc-based desulfurizing agent, a copper-zinc-aluminum-based desulfurizing agent, or the like can be used.

  The super high-order desulfurization agent is a catalyst that takes in and removes hydrogen sulfide converted from a sulfur compound by a catalyst. Such an ultra-high order desulfurization agent exhibits an excellent desulfurization action at a high temperature of 200 to 300 ° C. (for example, 250 to 300 ° C.). Therefore, the desulfurizer 11a6 is disposed at a location where the inside is in a high temperature state of 200 to 300 ° C. (for example, 250 to 300 ° C.). For example, the desulfurizer 11a6 is disposed in the casing 31 of the fuel cell module 30 that is brought to a high temperature state by the combustion unit 36 described later or on the outer surface of the casing 31. In addition, the fuel cell system 1 is provided with a recycle gas pipe 39 in connection with the use of an ultra-high order desulfurization agent as a desulfurization agent.

  The recycle gas pipe 39 connects a reformed gas supply pipe 38 that supplies the reformed gas from the reforming unit 33 to the fuel cell 34 and a reforming material supply pipe 11a that supplies the reforming raw material to the desulfurizer 11a6. And a part of the reformed gas that is returned to the desulfurizer 11a6 as recycled fuel. As described above, the reformed gas contains hydrogen.

  A first end of the recycle gas pipe 39 is connected to a reformed gas supply pipe 38 that supplies a reformed gas from the reforming unit 33 to the fuel cell 34. The second end of the recycle gas pipe 39 is located upstream of the desulfurizer 11a6 of the reforming raw material supply pipe 11a, more specifically, the location of the raw material pump 11a5 of the reforming raw material supply pipe 11a and the pressure adjusting device. 11a4 is connected to the arrangement site. As a result, part of the reformed gas flowing from the reforming unit 33 through the reformed gas supply pipe 38 is returned to the reforming raw material supply pipe 11a through the recycle gas pipe 39 as recycled fuel.

  In this way, part of the reformed gas is returned to the reforming raw material supply pipe 11a, so that hydrogen in the reformed gas is mixed with the reforming raw material, and the desulfurizer 11a6 is passed through the reforming raw material supply pipe 11a. It is sent to the super high-order desulfurization agent. As a result, the sulfur compound in the reforming raw material reacts with hydrogen to generate hydrogen sulfide, and the hydrogen sulfide is removed by the superhigh-order desulfurization agent.

  The recycle gas pipe 39 is provided with an orifice 39a. The orifice 39a is provided with a flow path hole (not shown), and the flow rate of the reformed gas returned through the recycle gas pipe 39 by the flow path hole is adjusted to a predetermined flow rate.

  Further, the recycle gas pipe 39 is disposed from the inside of the fuel cell module 30 that is brought into a high temperature state by the combustion unit 36 to the outside of the fuel cell module 30 at a lower temperature than inside the fuel cell module 30. As a result, the temperature of the reformed gas, which was relatively high in the fuel cell module 30, decreases when passing outside the fuel cell module 30, so that the water vapor contained in the reformed gas is condensed and drain water ( Condensed water) is produced. This drain water is led out to the mixed water pipe 40.

  As shown in FIG. 1 and FIG. 2, the mixed water pipe 40 is provided in a U shape that opens upward from below the gas discharge port 12 a. The mixed water pipe 40 has a first portion 40a. The first part 40 a is a flow path at the bottom of the mixed water pipe 40. The first portion 40 a is formed at the bottom of the mixed water pipe 40 so as to extend in the left-right direction.

  The mixed water pipe 40 has a first end (right end) which is a condensed water inlet 40 b for introducing condensed water from the condenser 12, and a second end (left end) which is a drain water inlet for introducing drain water from the recycle gas pipe 39. 40c. The condensed water inlet 40 b is disposed on the bottom wall of the condenser 12.

  The drain water introduction port 40 c is connected to the side wall of the recycle gas pipe 39 on the upstream side of the orifice 39 a in the recycle gas pipe 39. In the recycle gas pipe 39, since the upstream side of the orifice 39a has a positive pressure, the drain water flows into the mixed water pipe 40 without passing through the orifice 39a. Thereby, the inflow of drain water to the reforming raw material supply pipe 11a is suppressed.

  In the mixed water pipe 40, the drain water and the condensed water are mixed. The mixed water pipe 40 is disposed between the bottom (first portion 40a) and the condensed water inlet 40b and below the drain water inlet 40c, and is a mixed water for deriving mixed water in which the drain water and condensed water are mixed. A lead-out port 40d is provided. The mixed water outlet 40d is formed so as to open on the side wall of the mixed water pipe 40. The mixed water derived from the mixed water outlet 40d is supplied to the water tank 14 through the reformed water outlet pipe 41.

  The water tank 14 is disposed above the first portion 40a. Specifically, the water tank 14 is disposed between the first portion 40a and the drain water inlet 40c in the vertical direction. The water tank 14 is formed in a bottomed cylindrical shape that opens upward. The water tank 14 stores the reformed water therein. The water tank 14 is provided with a water outlet 14a and a water outlet 14b.

  The water discharge port 14a discharges the reformed water to the outside below the drain water introduction port 40c. The water discharge port 14a is formed in the upper part of the water tank 14 below the drain water introduction port 40c, and is provided so that the reformed water can be discharged to the outside. That is, the upper limit of the water level of the water tank 14 is the same height as the lower end of the water discharge port 14a.

  The water outlet 14b is formed below the water outlet 14a, is connected to the lower end of the water supply pipe 11b, and guides the reformed water toward the evaporation section 32. The water tank 14 is provided with a water level sensor 14c.

  The water level sensor 14 c detects the water level of the water tank 14. The water level of the water tank 14 is a height from the inner bottom surface of the water tank 14 to the water surface Sm of the water tank 14. The water level sensor 14c is, for example, a reed switch type water level sensor having a float 14c1.

  The water level sensor 14c outputs a first on signal when the water level of the water tank 14 is higher than the first predetermined water level Sw1, and a first off signal when the water level of the water tank 14 is equal to or lower than the first predetermined water level Sw1. Output to. The first predetermined water level Sw1 is provided between the water outlet 14b and the water outlet 14a in the vertical direction.

  When the first off signal is output, water from the water source W (for example, a water pipe) passes through the water supply pipe 42 and passes through the first water purification unit 42a disposed in the water supply pipe 42 as reformed water. It is supplied to the tank 14. The 1st water refinement | purification part 42a refine | purifies water. The control device 15 includes a water supply control unit 15a that opens the on-off valve 42b disposed in the water supply pipe 42 when the first off signal is output (see FIG. 3). The on-off valve 42b is a normally closed electromagnetic valve.

  The reforming water outlet pipe 41 is disposed above the first portion 40a and below the drain water inlet 40c, and leads the mixed water led out from the mixed water outlet 40d to the water tank 14 as reformed water. A second water purification unit 43 (corresponding to the water purification unit of the present invention) for purifying the mixed water is arranged.

  The first end of the reforming water outlet pipe 41 is a mixed water inlet 41a that is connected to the mixed water outlet 40d and into which the mixed water is introduced. The second end of the reforming water outlet pipe 41 is a reforming water outlet 41b that is connected to the lower side of the side wall of the water tank 14 and guides the reforming water. The reforming water outlet pipe 41 extends leftward from the mixed water outlet 40d and then bends downward and extends downward, and is further bent leftward so as to be connected to the water tank 14. . Further, the second part 41c, which is the uppermost part in the flow path of the reforming water outlet pipe 41, is disposed above the water discharge port 14a. The second part 41c is a part including the mixed water inlet 41a in the first embodiment.

  The second water purification unit 43 contains an ion exchange resin that purifies the mixed water. The 2nd water refinement | purification part 43 is arrange | positioned so that mixed water may flow downward from upper direction. The reformed water outlet pipe 41 guides the mixed water purified by the second water purification unit 43 to the water tank 14 as the reformed water.

  The first boundary surface Sk1 and the second boundary surface Sk2 are mixed so that the height along the vertical direction is the predetermined height Hs when the first boundary surface Sk1 is located at the first position P1. A water pipe 40, a reforming water outlet pipe 41, and a water tank 14 are provided.

  The first boundary surface Sk <b> 1 is a boundary surface between the reformed gas and the mixed water, which is located at a portion on the drain water inlet 40 c side from the first portion 40 a in the flow path of the mixed water pipe 40.

  The first position P1 is a position in the vertical direction of the first boundary surface Sk1, and is a lower limit position where the reformed gas does not flow out from the first boundary surface Sk1 to the first portion 40a. When the reformed gas having a predetermined pressure acts on the first boundary surface Sk1, the first boundary surface Sk1 is positioned at the first position P1. The predetermined pressure is set to a pressure larger than the normal pressure range of the reformed gas pressure during operation of the fuel cell system 1. Specifically, the first position P1 is the same height as the uppermost end of the first part 40a.

  When the first boundary surface Sk1 is positioned below the first position P1, the reformed gas flows out to the first portion 40a. In this case, it is conceivable that the reformed gas flows out from the gas discharge port 12 a of the condenser 12 through the condensed water inlet 40 b from the first portion 40 a of the mixed water pipe 40.

  The second boundary surface Sk2 is located at least at a portion on the mixed water outlet port 40d side from the first portion 40a in the flow path of the mixed water pipe 40, and communicated with the first boundary surface Sk1 via the mixed water and It is the interface with the atmosphere.

  In the first embodiment, the second boundary surface Sk2 is reformed at a portion closer to the mixed water outlet 40d than the first portion 40a in the flow path of the mixed water pipe 40 during the power generation operation of the fuel cell system 1. It is located at the same height as the second part 41c (specifically, the lowermost end of the mixed water inlet 41a) of the flow path of the water outlet pipe 41 (details will be described later). In the first embodiment, the height along the vertical direction between the first position P1 and the lowest end of the mixed water inlet 41a is set to the predetermined height Hs. In the present embodiment, the second boundary surface Sk2 communicates with the atmosphere via the condensed water inlet 40b and the gas outlet 12a of the condenser 12.

  The predetermined height Hs is such that the reformed gas flows out from the first boundary surface Sk1 to the first portion 40a by the mixed water between the first boundary surface Sk1 and the second boundary surface Sk2 located at the first position P1. It is a regulated height. That is, the predetermined height Hs is the pressure of the reformed gas acting on the first boundary surface Sk1 located at the first position P1, and the pressure of the mixed water between the first boundary surface Sk1 and the second boundary surface Sk2. Are equal heights. In the first embodiment, when the reformed gas of a predetermined pressure acts on the first boundary surface Sk1 and the first boundary surface Sk1 is positioned at the first position P1, the first boundary surface Sk1 and the second boundary surface Sk2 The pressure acting on the first boundary surface Sk1 by the mixed water between the two becomes a predetermined pressure. Thereby, the outflow of the reformed gas from the first boundary surface Sk1 to the first portion 40a is suppressed.

  In this way, the reforming water outlet pipe 41 and the water tank are set such that the height along the vertical direction between the first boundary surface Sk1 and the second boundary surface Sk2 located at the first position P1 is the predetermined height Hs. By providing 14, the mixed water pipe 40 and the reformed water outlet pipe 41 constitute a water seal structure for the reformed gas.

  Next, the operation of the fuel cell system 1 until the drain water and the condensed water are supplied as reformed water to the water tank 14 during the power generation operation of the fuel cell system 1 described above will be described with reference to FIG.

  During the power generation operation of the fuel cell system 1, the control device 15 controls the power generated by the fuel cell 34 to be the power consumption of the external power load 16 c (load following operation). The control device 15 adjusts the flow rate of the reforming raw material and the flow rate of the reforming water according to the power generated by the fuel cell 34.

  During the power generation operation of the fuel cell system 1, drain water is generated in the recycle gas pipe 39 as described above. The drain water is introduced into the mixed water pipe 40 from the drain water inlet 40c. Further, during the power generation operation of the fuel cell system 1, condensed water is generated in the condenser 12 as described above. Condensed water is introduced into the mixed water pipe 40 from the condensed water inlet 40b.

  The drain water and the condensed water are mixed in the mixed water pipe 40 and accumulated in the first portion 40a as mixed water. When the mixed water further increases, the mixed water is introduced from the mixed water outlet 40d into the mixed water inlet 41a. As described above, the uppermost second portion 41 c in the flow path of the reforming water outlet pipe 41 is a portion including the mixed water inlet 41 a and is a water outlet that is the upper limit of the water level of the water tank 14. It is located above 14a. Therefore, the mixed water flows down from the mixed water inlet 41a to the water tank 14. Therefore, the second boundary surface Sk2 is located at the same position as the lowermost end of the mixed water inlet 41a in a portion closer to the condensed water inlet 40b than the first portion 40a in the flow path of the mixed water pipe 40.

  On the other hand, the first boundary surface Sk1 is located below the second boundary surface Sk2. The difference in height along the vertical direction between the first boundary surface Sk1 and the second boundary surface Sk2 at this time is caused by the difference between the pressure of the reformed gas during the power generation operation of the fuel cell system 1 and the atmospheric pressure. .

  Since the pressure of the reformed gas during the power generation operation of the fuel cell system 1 is within the normal pressure range, it is smaller than the predetermined pressure described above. Therefore, the height Hd along the vertical direction of the first boundary surface Sk1 and the second boundary surface Sk2 at this time is smaller than the predetermined height Hs. For this reason, the first boundary surface Sk1 is located above the first position P1. Therefore, the reformed gas does not flow out from the first boundary surface Sk1 through the first portion 40a and thus to the second boundary surface Sk2 and thus to the outside.

  The mixed water introduced into the reformed water outlet pipe 41 is purified when passing through the second water purifying unit 43 and supplied to the water tank 14 as reformed water. The reformed water is stored in the water tank 14 and is led out from the water lead-out port 14b toward the evaporation unit 32 by driving the reforming water pump.

  Further, when the amount of drain water and condensed water generated is larger than the amount of reforming water supplied to the evaporation section 32, the water level of the water tank 14 rises. When the water level in the water tank 14 reaches the water discharge port 14a, the reformed water is discharged to the outside through the water discharge port 14a.

  Since the mixed water outlet 40d is positioned above the water outlet 14a, the second boundary surface Sk2 does not rise above the mixed water outlet 40d. The first boundary surface Sk1 is positioned below the second boundary surface Sk2 and thus the mixed water outlet 40d. Furthermore, a drain water inlet 40c and a gas outlet 12a are provided above the mixed water outlet 40d. Accordingly, the mixed water does not reach the recycle gas pipe 39 and the gas discharge port 12a.

  On the other hand, when the amount of drain water and condensed water generated is smaller than the amount of reforming water supplied to the evaporation section 32, the water level of the water tank 14 is lowered. When the water level of the water tank 14 decreases to the first predetermined water level Sw1, as described above, the water from the water source W is supplied to the water tank 14 as reformed water based on the output signal of the water level sensor 14c. The

  According to the first embodiment, the fuel cell system 1 includes a fuel cell 34 that generates power using a reformed gas containing hydrogen and an oxidant gas, an evaporation unit 32 that generates water vapor from the reformed water, and a reforming device. A reforming unit 33 that generates reformed gas from the raw material and water vapor and supplies the reformed gas to the fuel cell 34; a sulfur component contained in the reforming raw material is removed by hydrogen; A desulfurizer 11a6 that supplies the reforming unit 33, a reformed gas supply pipe 38 that supplies the reformed gas from the reforming unit 33 to the fuel cell 34, and a reforming material that supplies the reforming material to the desulfurizer 11a6 A recycle gas pipe 39 connected to the supply pipe 11a and returning a part of the reformed gas as a recycle fuel to the desulfurizer 11a6, which is a recycle gas pipe 39 in which drain water is generated, and combustion including water vapor from the fuel cell 34 Condensed exhaust gas and condensed water And a condenser 12 having a gas discharge port 12a for discharging the condensed combustion exhaust gas, and a U-shape opening upward from below the gas discharge port 12a. Condensed water inlet 40b for introducing condensed water, the second end is a drain water inlet 40c for introducing drain water from the recycle gas pipe 39, and between the bottom and the condensed water inlet 40b and the drain water introduction A mixed water pipe 40 disposed below the port 40c and provided with a mixed water outlet port 40d for leading mixed water in which drain water and condensed water are mixed, and a first portion which is a flow path at the bottom of the mixed water pipe 40 A water tank 14 that is disposed above 40a, stores the reformed water, and has a water discharge port 14a that discharges the reformed water to the outside below the drain water introduction port 40c; A second water purification unit 43 that is disposed further above and below the drain water inlet 40c and that leads the mixed water led out from the mixed water outlet 40d as reformed water to the water tank 14 and purifies the mixed water. And a reformed water outlet pipe 41 arranged. A first boundary surface Sk1, which is a boundary surface between the reformed gas and the mixed water, located at a portion on the drain water inlet 40c side from the first portion 40a in the flow path of the mixed water pipe 40, and a flow path of at least the mixed water pipe 40 Of the second boundary surface Sk2 that is located at a portion closer to the condensed water inlet 40b than the first portion 40a and communicates with the first boundary surface Sk1 through the mixed water, which is a boundary surface between the mixed water and the atmosphere. The height along the vertical direction is a lower limit position where the reformed gas having a predetermined pressure acts on the first boundary surface Sk1 so that the reformed gas does not flow out from the first boundary surface Sk1 to the first portion 40a. When the first boundary surface Sk1 is located at the first position P1, the water is mixed between the first boundary surface Sk1 and the second boundary surface Sk2 to change the first boundary surface Sk1 to the first portion 40a. The outflow of quality gas is regulated As a predetermined height Hs, mixed water pipe 40, the reforming water outlet pipe 41 and the water tank 14 is provided.

  According to this, the height along the vertical direction between the first boundary surface Sk1 located at the first position P1 and the second boundary surface Sk2 communicated with the first boundary surface Sk1 via the mixed water is a predetermined height. A mixed water pipe 40, a reformed water outlet pipe 41, and a water tank 14 are provided so as to be Hs. For this reason, the mixed water between the first boundary surface Sk1 and the second boundary surface Sk2 suppresses the outflow of the reformed gas from the first boundary surface Sk1 to the first portion 40a, the second boundary surface Sk2, and thus to the outside. The Therefore, a water seal member such as a steam trap or a U-shaped tube as in the prior art becomes unnecessary, and the number of parts of the fuel cell system 1 can be reduced. Therefore, cost reduction of the fuel cell system 1 can be achieved.

  Moreover, since drain water is collect | recovered by the water tank 14 without being discharged | emitted outside like the prior art, the water self-sustained operation of the fuel cell system 1 can be enabled. In the water self-sustained operation, the amount of water vapor required in the reforming unit 33 is set to the amount of reformed water in the water tank 14 without replenishment from the outside, that is, the amount of condensed water from the condenser 12 and This is the operation of the fuel cell system 1 that can be secured only by the amount of drain water. In other words, the water self-sustained operation is an operation of the fuel cell system 1 that can perform a power generation operation without supplying water to the water tank 14 from the outside.

  In addition, the second part 41c, which is the uppermost part in the flow path of the reforming water outlet pipe 41, is arranged above the water discharge port 14a, so that the second boundary surface Sk2 becomes the flow path of the mixed water pipe 40. In the site | part of the condensed water inlet 40b side from the 1st site | part 40a, it is located in the same height as the 2nd site | part 41c.

  According to this, the second boundary surface Sk2 is a second portion 41c (the second portion 41c of the flow path of the reforming water outlet tube 41 at a portion closer to the condensed water inlet 40b than the first portion 40a in the flow passage of the mixed water tube 40. Specifically, the mixed water pipe 40, the reforming water outlet pipe 41, and the water tank 14 are provided so as to be positioned at the same height as the lowermost end of the mixed water inlet 41a. Therefore, the water seal structure for the reformed gas can be reliably configured by the mixed water in the mixed water pipe 40.

<First Modification of First Embodiment>
Next, with respect to the first modification of the first embodiment, portions different from the first embodiment described above will be mainly described with reference to FIG.

  In the first embodiment described above, the reforming water lead-out pipe 41 is formed so as to extend downward from above, but the reforming water lead-out pipe 141 of the first modified example has a U shape that opens upward. It is formed in a shape. The reformed water outlet 141b is provided so as to open above the water tank 14. Moreover, the 2nd water refinement | purification part 43 of this 1st modification is arrange | positioned so that mixed water may flow upwards from the downward direction.

  Also in the first modified example, the uppermost second portion 141c in the flow path of the reforming water outlet tube 141 is a portion including the mixed water inlet 141a and the water outlet of the water tank 14 It is located above 14a. Therefore, the second boundary surface Sk2 is located at the same position as the lowermost end of the mixed water inlet 141a in a portion closer to the condensed water inlet 40b than the first portion 40a in the flow path of the mixed water pipe 40. In the first modification, the height along the vertical direction between the first position P1 and the lowermost end of the mixed water inlet 141a is set to a predetermined height Hs.

<Second Modification of First Embodiment>
Next, with respect to the second modification of the first embodiment, portions different from the first embodiment described above will be mainly described with reference to FIG. The reforming water outlet tube 241 of the second modification is formed in a U shape that opens upward.

  The reformed water outlet 241b is provided so as to open above the water tank 14 (that is, above the water outlet 14a). In the second modification, the uppermost second portion 241c in the flow path of the reforming water outlet pipe 241 is a portion including the reforming water outlet 241b and the water outlet of the water tank 14 It is provided so that it may be located above 14a. Therefore, in the second modified example, the mixed water flows down from the reformed water outlet 241b to the water tank 14.

  Therefore, the second boundary surface Sk2 has a second portion 241c (specifically modified) in a portion closer to the condensed water inlet 40b than the first portion 40a in the flow path of the mixed water pipe 40 and in the reformed water outlet pipe 241. It is located at the same position as the bottom end of the quality water outlet 241b. In the second modification, the height along the vertical direction between the first position P1 and the lowermost end of the reforming water outlet 241b is set to the predetermined height Hs.

<Third Modification of First Embodiment>
Next, with respect to the third modification example of the first embodiment, parts different from the second modification example of the first embodiment described above will be mainly described with reference to FIG. The 2nd water refinement | purification part 43 of this 3rd modification is arrange | positioned so that mixed water may flow downward from upper direction.

  Also in the third modified example, as in the second modified example described above, the uppermost second part 341c in the flow path of the reformed water outlet pipe 341 is a part including the reformed water outlet 341b. And it is located above the water discharge port 14a of the water tank 14. Therefore, the second boundary surface Sk2 has a second portion 341c (specifically modified) in the portion closer to the condensed water inlet 40b than the first portion 40a in the flow path of the mixed water pipe 40 and the reformed water outlet pipe 341. It is located at the same position as the bottom end of the quality water outlet 341b. In the third modification, the height along the vertical direction between the first position P1 and the lowermost end of the reforming water outlet 341b is set to the predetermined height Hs.

<Second embodiment>
Next, a second embodiment of the fuel cell system 1 according to the present invention will be described with reference to FIG.

  In the second embodiment, the second part 441c, which is the uppermost part in the flow path of the reforming water outlet pipe 441, is a part including the reforming water outlet 441b. The reformed water outlet 441b is disposed above the first predetermined water level Sw1 on the side wall of the water tank 14 and at a position below the water outlet 14a.

  Moreover, similarly to 1st embodiment mentioned above, when the water level of the water tank 14 becomes below 1st predetermined water level Sw1, the reforming water is supplied to the water tank 14 from the water source W (water supply control part 15a). Further, when the water level of the water tank 14 reaches the water discharge port 14a, the reformed water is discharged to the outside from the water discharge port 14a. That is, the water level of the water tank 14 varies between the first predetermined water level Sw1 and the water discharge port 14a.

  Therefore, the second boundary surface Sk2 communicated with the first boundary surface Sk1 via the mixed water (and the reformed water (purified mixed water)), the water level of the water tank 14 is higher than the reformed water outlet 441b. When located, the water tank 14 and the mixed water pipe 40 are located at the same height as the water level of the water tank 14. Further, when the water level of the water tank 14 is located at the same height as the reforming water outlet 441b, the second boundary surface Sk2 is located in the mixed water pipe 40, the water tank 14, and the reforming water as shown in FIG. In the outlet pipe 441, it is located at the same height as the water level of the water tank 14.

  Further, when the water level of the water tank 14 is located below the reforming water outlet 441b, the reforming water flows down into the water tank 14 from the reforming water outlet 441b. Therefore, in this case, the second boundary surface Sk2 is located at the same position as the lowermost end of the reforming water outlet 441b in the mixed water pipe 40 and the reforming water outlet pipe 441. In the second embodiment, the height along the vertical direction between the first position P1 and the lowermost end of the reforming water outlet 441b is set to the predetermined height Hs. Therefore, the height in the vertical direction between the first boundary surface Sk1 and the second boundary surface Sk2 located at the first position P1 is equal to or greater than the predetermined height Hs.

  According to the second embodiment, in the fuel cell system 1, the second part 441c, which is the uppermost part in the flow path of the reforming water outlet pipe 441, is arranged at a position below the water discharge port 14a. The second boundary surface Sk2 is located at the same height as one of the water level of the water tank 14 above the second part 441c and the second part 441c.

  According to this, the second boundary surface Sk2 is located at the same height as one of the second part (specifically, the lowermost end of the reforming water outlet 441b) and the water level of the water tank 14 above the second part. Thus, a mixed water pipe 40, a reforming water outlet pipe and a water tank 14 are provided. Therefore, the water seal structure for the reformed gas can be reliably configured by the mixed water (reformed water) in the mixed water pipe 40, the reformed water outlet pipe 441 and the water tank 14.

<First Modification of Second Embodiment>
Next, the first modification of the second embodiment of the fuel cell system 1 according to the present invention will be described with reference to FIG.

  In the first modified example, the second part 541c, which is the uppermost part in the flow path of the reforming water outlet pipe 541, is a part including the mixed water inlet 541a. The mixed water inlet 541a is arranged above the first predetermined water level Sw1 on the side wall of the water tank 14 and at a position below the water outlet 14a. Similarly to the second embodiment described above, the water level of the water tank 14 varies between the first predetermined water level Sw1 and the water discharge port 14a.

  Therefore, the second boundary surface Sk2 communicated with the first boundary surface Sk1 via the mixed water (and the reformed water (purified mixed water)) is such that the water level of the water tank 14 is located above the mixed water inlet 541a. In this case, the water tank 14 and the mixed water pipe 40 are located at the same height as the water level of the water tank 14. Further, when the water level of the water tank 14 is located at the same height as the mixed water inlet 541a, the second boundary surface Sk2 is, as shown in FIG. 9, in the mixed water pipe 40, the water tank 14, and the reformed water derivation. In the pipe 541, it is located at the same height as the water level of the water tank 14.

  Furthermore, when the water level of the water tank 14 is located below the mixed water inlet 541a, the mixed water flows down from the mixed water inlet 541a. Therefore, in this case, the second boundary surface Sk2 is located at the same position as the lowest end of the mixed water inlet 541a in the mixed water pipe 40. In the first modification, the height along the vertical direction between the first position P1 and the lowest end of the mixed water inlet 541a is set to the predetermined height Hs.

<Second Modification of Second Embodiment>
Next, a second modification of the second embodiment of the fuel cell system 1 according to the present invention will be described with reference to FIG. 10 mainly for parts that are different from the first modification of the second embodiment described above.

  In the second modified example, the reforming water outlet pipe 641 is disposed below the second predetermined water level Sw2 (corresponding to the predetermined water level of the present invention) of the water tank 14. The second predetermined water level Sw2 is set below the first predetermined water level Sw1. The reformed water outlet 641b is connected to the lower side (for example, the bottom) of the second predetermined water level Sw2 of the water tank 14.

  Similar to the second embodiment described above, the water level of the water tank 14 varies between the first predetermined water level Sw1 and the water outlet 14a. Further, the reforming water outlet pipe 641 is positioned below the first predetermined water level Sw1. Therefore, the second boundary surface Sk2 is located at the same height as the water level of the water tank 14 in the water tank 14 and the mixed water pipe 40.

  Further, the height along the vertical direction between the first position P1 and the second predetermined water level Sw2 of the water tank 14 is provided to be a predetermined height Hs. Therefore, the height along the vertical direction between the second boundary surface Sk2 and the first position P1 is equal to or higher than the predetermined height Hs.

  Moreover, the control apparatus 15 is further provided with the stop control part 615b, as shown in FIG. The stop control unit 615b performs control to stop the supply of the reformed gas to the fuel cell 34 when the water level of the water tank 14 detected by the water level sensor 14c is equal to or lower than the second predetermined water level Sw2.

  For example, even when the water level of the water tank 14 becomes equal to or lower than the first predetermined water level Sw1 due to the failure of the on-off valve 42b, the reforming water is not supplied to the water tank 14, and the water level of the water tank 14 is set to the second predetermined level. When the water level Sw2 is reached, the control device 15 performs control so as to close the shutoff valve 11a1. As a result, the supply of the reformed gas to the fuel cell 34 is stopped, so that the flow of the reformed gas into the recycle gas pipe 39 and consequently the mixed water pipe 40 is stopped. Therefore, the reformed gas is restricted from flowing out through the mixed water pipe 40.

  According to the second modification of the second embodiment, the reforming water outlet pipe 641 is disposed below the second predetermined water level Sw2 of the water tank 14. The fuel cell system 1 further includes a water level sensor 14 c that detects the water level of the water tank 14. The height along the vertical direction between the first boundary surface Sk1 located at the first position P1 and the second predetermined water level Sw2 of the water tank 14 is set to be a predetermined height Hs. The control device 15 further includes a stop control unit 615b that performs control to stop the supply of the reformed gas to the fuel cell 34 when the water level of the water tank 14 detected by the water level sensor 14c is equal to or lower than the second predetermined water level Sw2. I have.

  According to this, when the water level of the water tank 14 detected by the water level sensor 14c is equal to or lower than the second predetermined water level Sw2, the supply of the reformed gas to the fuel cell 34 is stopped. That is, the water level in the water tank 14 becomes lower than the second predetermined water level Sw2, so that the height along the vertical direction between the first position P1 and the second boundary surface Sk2 becomes lower than the predetermined height Hs. The supply of quality gas is stopped. Therefore, the reformed gas is more reliably prevented from being discharged from the mixed water pipe 40 through the reformed water outlet pipe 641 and the water tank 14.

<Other variations>
In each of the above-described embodiments, an example of the fuel cell system is shown. However, the present invention is not limited to this, and other configurations can be adopted. For example, the water level sensor 14c is a reed switch type water level sensor, but may be a capacitance type water level sensor.

  Further, in the first embodiment and the modifications of the first embodiment described above, the second portions 41c, 141c, and 241c are mixed water inlets 41a, 141a, and 541a and reformed water outlets 241b, 341b and 441b, respectively. Although it is a part including one side, it may be provided in a part between the first end and the second end of the reforming water outlet pipes 41, 141, 241 instead.

  In each of the above-described embodiments and modifications, the first position P1, the lowest end of the mixed water inlets 41a, 141a, 541a, the reforming water outlets 241b, 341b, 441b, or the second predetermined water level Sw2 Although the height along the vertical direction is set to the predetermined height Hs, these heights may be set to be equal to or higher than the predetermined height Hs.

  In the second modification of the second embodiment described above, the stop control unit 615b determines that the water level of the water tank 14 detected by the water level sensor 14c is equal to or lower than the second predetermined water level Sw2. However, instead of this, the fuel cell system 1 may be stopped.

  Further, the shape, arrangement position, and the like of the recycle gas pipe 39, the mixed water pipe 40, the reformed water outlet pipe 41, 141, 241, 341, 441, 541, 641 and the water tank 14 may be used without departing from the scope of the present invention. It may be changed.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 11 (30) ... Fuel cell module, 11a ... Reforming raw material supply pipe, 11a1 ... Shut-off valve, 11a6 ... Desulfurizer, 12 ... Condenser, 12a ... Gas discharge port, 14 ... Water tank, DESCRIPTION OF SYMBOLS 14a ... Water discharge port, 14c ... Water level sensor, 15 ... Control apparatus, 21 ... Hot water tank, 30 ... Fuel cell module, 32 ... Evaporating part, 33 ... Reforming part, 34 ... Fuel cell, 38 ... Reformed gas supply pipe 39 ... Recycle gas pipe, 40 ... Mixed water pipe, 40a ... First part, 40b ... Condensed water inlet, 40c ... Drain water inlet, 40d ... Mixed water outlet, 41 ... Reformed water outlet pipe, 41a ... Mixed Water inlet, 41b ... reformed water outlet, 41c ... second part, 43 ... second water purification unit (water purification unit), 615b ... stop control unit, P1 ... first position, Sk1 ... first boundary surface, Sk2 ... second boundary surface, Sw1 ... first predetermined water , Sw2 ... second predetermined level (predetermined level).

Claims (4)

A fuel cell that generates electric power using a reformed gas containing hydrogen and an oxidant gas;
An evaporation section for generating water vapor from the reformed water;
A reforming unit that generates the reformed gas from the reforming raw material and the steam and supplies the reformed gas to the fuel cell;
A desulfurizer for removing sulfur components contained in the reforming raw material with the hydrogen and supplying the reforming raw material to the reforming section;
A reformed gas supply pipe for supplying the reformed gas from the reforming section to the fuel cell and a reforming material supply pipe for supplying the reforming raw material to the desulfurizer are connected, and the reformed gas is connected. A part of the recycled gas pipe for returning to the desulfurizer as recycled fuel, wherein the recycled gas pipe for generating drain water,
A condenser having a gas outlet for condensing the exhaust gas containing the water vapor from the fuel cell to generate condensed water and discharging the condensed exhaust gas;
Provided in a U-shape that opens upward from below the gas discharge port, the first end is a condensed water inlet for introducing the condensed water from the condenser, and the second end is from the recycle gas pipe A drain water introduction port for introducing drain water, disposed between the bottom and the condensed water introduction port and below the drain water introduction port, and mixed water in which the drain water and the condensed water are mixed. A mixed water pipe provided with a mixed water outlet for discharging;
A water outlet that is disposed above a first portion that is a flow path at the bottom of the mixed water pipe, stores the reformed water, and discharges the reformed water to the outside below the drain water inlet. Having a water tank;
The mixed water, which is disposed above the first part and below the drain water inlet, is led out from the mixed water outlet to the water tank as the reformed water and purifies the mixed water. A fuel cell system comprising a reforming water outlet pipe in which a water purification unit is disposed,
A first boundary surface, which is a boundary surface between the reformed gas and the mixed water, located at a portion on the drain water inlet side from the first portion in the flow path of the mixed water pipe;
The boundary surface between the mixed water and the atmosphere, which is located at least at the portion closer to the condensed water inlet than the first portion in the flow path of the mixed water pipe and communicated with the first boundary surface via the mixed water The height along the vertical direction with the second boundary surface is
When the reformed gas having a predetermined pressure acts on the first boundary surface, the reformed gas does not flow out from the first boundary surface to the first portion. When one boundary is located,
The mixed water between the first boundary surface and the second boundary surface is not less than a predetermined height at which the outflow of the reformed gas from the first boundary surface to the first portion is regulated. A fuel cell system provided with the mixed water pipe, the reformed water outlet pipe, and the water tank. By arranging the second part, which is the uppermost part in the flow path of the reformed water outlet pipe, at a position above the water discharge port,
The fuel cell system according to claim 1, wherein the second boundary surface is located at the same height as the second portion. By arranging the second part, which is the uppermost part in the flow path of the reformed water outlet pipe, at a position below the water discharge port,
2. The fuel cell system according to claim 1, wherein the second boundary surface is located at the same height as one of the water level of the water tank and the second portion above the second portion. The reforming water outlet pipe is disposed at a position below a predetermined water level of the water tank;
A water level sensor for detecting the water level of the water tank;
The height along the vertical direction between the first boundary surface located at the first position and the predetermined water level of the water tank is set to be equal to or higher than the predetermined height,
The apparatus according to claim 3, further comprising a stop control unit that performs control to stop supply of the reformed gas to the fuel cell when the water level detected by the water level sensor is equal to or lower than the predetermined water level. The fuel cell system described.

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