JP2007317617A - Fuel cell unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell unit of which occupation space is reduced, and the water content separated by the steam separator is supplied to a circulation water tank while leakage of gas fuel is prevented with a single configuration. <P>SOLUTION: The fuel cell unit at least comprises a reformer; a fuel cell to which the gas fuel generated by the reformer is supplied; a steam separator 16a for separating water content from the gas fuel; and a circulation water tank 24 which is connected to the steam separator through a communication pipe 22a, and is supplied with the water content separated by the steam separator for holding it as the circulation water for the reformer. The circulation water tank is disposed below the steam separator in terms of gravitational direction, and an end 22a1 of the communication pipe is positioned in a circulation water W1 held in the circulation water tank. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell unit, and more particularly to a fuel cell unit provided with an air / water separator that separates moisture from gas fuel of a fuel cell.

  The gas fuel (anode gas) of the fuel cell produced by the reformer contains a lot of moisture. For this reason, if the fuel cell is supplied as it is, water clogging occurs near the gas fuel inlet of the fuel cell (the inlet of the anode electrode), resulting in a problem that hinders the flow of the gas fuel. In addition, since the gas fuel discharged from the fuel cell contains unused gas, it is recirculated to the combustion burner of the reformer and reused as fuel for the combustion burner. When supplied to the combustion burner, problems such as poor ignition of the combustion burner and increased calorie loss of the combustion burner due to latent heat occur.

In view of this, various fuel cell units have been proposed in the past in which an air / water separator that separates moisture from the gas fuel is provided in the flow path through which the gas fuel flows so that the moisture in the gas fuel is less likely to be supplied to a fuel cell or the like. (For example, refer to Patent Document 1). In addition, the water | moisture content isolate | separated with the steam separator is supplied to the circulating water tank which stores the circulating water for reformers, and is reused. At this time, in order to prevent the gas fuel of the steam separator from leaking to the circulating water tank, the water separated by the steam separator is temporarily stored in the storage tank to maintain a constant water level, and the storage tank When the water level exceeds a predetermined value, the water in the storage tank is supplied to the circulating water tank. In other words, the water level is sealed with the water separated by the steam separator.
JP 2002-134145 A

  However, in the technique described in Patent Document 1, since the storage tank is connected to the steam separator, there is a problem that the occupied space increases by the storage tank. In addition, since the communication pipe that connects the storage tank and the circulating water tank is equipped with a solenoid valve, electric power for opening and closing the solenoid valve and a harness for the solenoid valve are newly required. Since the opening / closing timing is determined by the water level of the storage tank, a sensor (for example, a liquid level sensor) for detecting the water level of the storage tank is also required, and there is a disadvantage that the configuration becomes complicated.

  Accordingly, the object of the present invention is to solve the above-mentioned problems, reduce the occupied space, and circulate water tank while preventing the leakage of gas fuel while keeping the water separated by the steam separator while having a simple configuration. It is to provide a fuel cell unit to be supplied to the vehicle.

  In order to solve the above-mentioned object, according to claim 1, a reformer, a fuel cell to which gas fuel generated by the reformer is supplied, and steam that separates moisture from the gas fuel At least a separator, and a circulating water tank connected to the steam / water separator via a communication pipe and supplied with water separated by the steam / water separator and stored as circulating water for the reformer In the fuel cell unit, the circulating water tank is disposed below in the gravity direction of the steam separator, and the end of the communication pipe is positioned in the circulating water stored in the circulating water tank. did.

  According to a second aspect of the present invention, the circulating water tank includes a chamber, and the end of the communication pipe is positioned in the circulating water stored in the chamber.

  According to a third aspect of the present invention, the circulating water tank is opened to the atmosphere, and the end of the communication pipe is connected to the pressure of the gas fuel and the atmospheric pressure from the surface of the circulating water stored in the circulating water tank. It was configured to extend to a position deeper than the head height corresponding to the difference.

  According to a fourth aspect of the present invention, the gas fuel is composed of anode gas.

  In the fuel cell unit according to claim 1, the circulating water tank for storing the circulating water for the reformer is configured to be disposed below in the gravity direction of the steam separator, that is, the steam separator. Since the separated water is configured to be directly supplied to the circulating water tank via the communication pipe, it is possible to eliminate the need for a storage tank that temporarily stores the water separated by the steam separator. Occupied space can be reduced. Further, the end of the communication pipe connecting the steam separator and the circulating water tank is positioned in the circulating water stored in the circulating water tank, that is, the gas fuel is supplied by the circulating water in the circulating water tank. Since it is configured to be liquid-sealed, it is possible to eliminate the need for conventional storage tanks, solenoid valves, liquid level sensors, etc. It can supply to a circulating water tank, preventing. Further, since there is no electromagnetic valve or liquid level sensor as in the prior art, it is advantageous in terms of cost.

  In the fuel cell unit according to claim 2, the circulating water tank includes the chamber, and the end of the communication pipe is configured to be positioned in the circulating water stored in the chamber. In addition, the gas fuel can be sealed with a part of the circulating water stored in the circulating water tank, specifically, a relatively small amount of circulating water stored in the chamber, and leakage of the gas fuel can be further prevented. .

  In the fuel cell unit according to claim 3, the circulating water tank is opened to the atmosphere, and the end of the communication pipe is connected to the surface of the circulating water stored in the circulating water tank. Since it is configured to extend to a position deeper than the head height corresponding to the difference in atmospheric pressure, in addition to the above effects, the moisture of the steam separator is supplied to the circulating water tank while further preventing leakage of gas fuel. can do.

  That is, in the communication pipe whose end is positioned in the circulating water of the circulating water tank, the water level of the water in the communicating pipe is pushed downward by the pressure of the gas fuel. More specifically, the level of the circulating water in the circulating water tank Therefore, it is pushed downward by the head height corresponding to the difference between the pressure of the gas fuel and the atmospheric pressure. Therefore, the end of the communication pipe is configured to extend from the surface of the circulating water in the circulating water tank to a position deeper than the head height corresponding to the difference between the pressure of the gas fuel and the atmospheric pressure. Even when the gas acts on the water surface in the communication pipe, moisture is always present near the lower end of the communication pipe, so that the gas fuel passes through the communication pipe and flows into the circulating water tank (leaks). This can be prevented.

  In the fuel cell unit according to the fourth aspect, since the gas fuel is constituted by the anode gas, the above effect can be obtained in the anode gas containing a large amount of moisture.

  The best mode of the fuel cell unit according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram for explaining a fuel cell unit according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a fuel cell unit. The fuel cell unit 10 includes a reformer 12, a fuel cell 14 to which gas fuel (anode gas) generated by the reformer 12 is supplied, and first and second air / water that separates moisture from the gas fuel. Separators (steam / water separators) 16a and 16b and first and second steam / water separators 16a and 16b are connected to the steam and water separators 16a and 16b via first and second communication pipes 22a and 22b, respectively. A circulating water tank 24 that is supplied with the water separated by 16a and 16b and stores it as circulating water for the reformer 12 is provided.

  Hereinafter, each element constituting the fuel cell unit 10 will be described. The reformer 12 is supplied with a reforming fuel (for example, city gas) and performs a steam reforming reaction to generate an anode gas. A reforming unit 12a that performs heating, and a heating unit (combustion burner) 12b that heats the reforming unit 12a.

  The reforming section 12a is fueled by a reforming fuel pipe 30 for supplying reforming fuel, a circulating water pipe 32 for supplying circulating water from the circulating water tank 24, and an anode gas generated by the reforming section 12a. An anode gas pipe 34 to be supplied to the battery 14 is connected. A reforming fuel supply source (not shown) is connected to the upstream side of the reforming fuel pipe 30. A circulating water pump 40 that pumps circulating water is disposed in the middle of the circulating water pipe 32. In this specification, “upstream” means upstream in the flow direction of fuel (reforming fuel, anode gas, etc.) flowing therethrough.

  The heating unit 12b is discharged from the fuel cell 14 and a combustion air pipe 42 for supplying air (hereinafter referred to as “combustion air”) used for combustion in a combustion burner (not shown) of the heating unit 12b. An anode offgas pipe 44 for supplying gas fuel (anode offgas) as a heating fuel for the combustion burner, and a branch from the reforming fuel pipe 30 through the first three-way valve 46, and the reforming fuel is burned. The heating fuel pipe 50 supplied as the heating fuel and the combustion exhaust pipe 52 for discharging the combustion exhaust gas generated in the combustion burner to the atmosphere are connected. A combustion air pump 54 that sucks and pumps air is disposed in the middle of the combustion air pipe 42.

  The fuel cell 14 includes an electrolyte membrane (solid polymer membrane), a cathode electrode (air electrode) and an anode electrode (fuel electrode) that sandwich the membrane, and a separator (none of which is shown) disposed outside each electrode. This is a known solid polymer fuel cell formed by stacking a plurality of single cells (cells) composed of

  A cathode gas pipe 56 through which air (cathode gas, specifically oxygen gas) to be supplied to the fuel cell 14 flows is connected to the inlet side of the cathode electrode of the fuel cell 14, while a fuel gas is connected to the outlet side. A cathode offgas pipe 60 that discharges cathode gas discharged from the battery 14 (hereinafter referred to as “cathode offgas”) to the atmosphere is connected. The cathode gas pipe 56 is provided with a cathode gas pump 62 that sucks and pumps air.

  The anode gas pipe 34 is connected to the inlet side of the anode electrode of the fuel cell 14. That is, the anode electrode inlet of the fuel cell 14 and the reformer 12 a of the reformer 12 are connected via the anode gas pipe 34. The anode off gas pipe 44 is connected to the outlet side of the anode electrode of the fuel cell 14. That is, the anode electrode outlet of the fuel cell 14 and the heating unit 12 b of the reformer 12 are connected via the anode offgas pipe 44.

  The fuel cell 14 is connected to an electronic control unit (hereinafter referred to as “ECU”) 64 composed of a microcomputer or the like. The ECU 64 is connected to each pump such as the circulating water pump 40, the first three-way valve 46, and the like, and controls the operation of these auxiliary machines.

  Further, the fuel cell 14 is connected to an exhaust heat recovery system 70 that recovers exhaust heat by generating hot water using exhaust heat generated from the fuel cell 14. The exhaust heat recovery system 70 is connected to the fuel cell 14 via a primary cooling water pipe 72 and a heat exchanger (solution heat exchanger) 74, and is connected to the heat exchanger 74 via a secondary cooling water pipe 76. A hot water storage tank 80 for storing water supplied from a water source (not shown) is also provided.

  As shown in the figure, a primary cooling water pump 82 for circulating the cooling water in the primary cooling water pipe 72 is arranged in the middle of the primary cooling water pipe 72 and also in the middle of the secondary cooling water pipe 76. A secondary cooling water pump 84 that circulates the cooling water in the cooling water pipe 76 is disposed.

  Thereby, the heat (exhaust heat) generated from the fuel cell 14 is first absorbed by the cooling water in the primary cooling water pipe 72 and supplied to the heat exchanger 74. Next, in the heat exchanger 74, heat is transferred between the cooling water in the primary cooling water pipe 72 and the cooling water in the secondary cooling water 76, and the heat supplied to the heat exchanger 74 is transferred to the hot water storage tank 80. Supplied. In the hot water storage tank 80, heat is exchanged between the cooling water in the secondary cooling water 76 and the water stored in the hot water storage tank 80, and the temperature of the water in the hot water storage tank 80 is raised, thereby generating hot water. . The hot water in the hot water storage tank 80 is supplied to a heat load (not shown) (for example, a hot water shower).

  The anode gas pipe 34 is provided with a first steam / water separator 16a that separates moisture from the anode gas, and the anode off-gas pipe 44 is provided with a second steam / water separator 16b that separates moisture from the anode off-gas. Is placed. An upstream side of the first gas / water separator 16 a of the anode gas pipe 34 is connected to an upstream side of the second gas / water separator 16 b of the anode off-gas pipe 44. A second three-way valve 90 is disposed at a connection portion between the anode gas pipe 34 and the anode off gas pipe 44.

  A circulating water tank 24 is disposed below the first and second steam / water separators 16a and 16b. The lower part 16a1 of the first steam separator 16a and the upper part 24a of the circulating water tank 24 are connected via the first communication pipe 22a, and the lower part 16b1 of the second steam separator 16b and the circulating water tank. The upper part 24a of 24 is connected via the 2nd communicating pipe 22b. Note that in this specification, the descriptions indicating the upper and lower relations such as the upper part, the lower part, the upper part and the lower part all represent the upper and lower relations in the direction of gravity.

  2 is an explanatory sectional view for explaining the circulating water tank 24 and the like shown in FIG. 1, and FIG. 3 is a sectional view taken along the line III-III of the circulating water tank 24 shown in FIG.

  As shown in FIGS. 2 and 3, the circulating water tank 24 has a substantially rectangular parallelepiped shape, and an opening 24a1 is provided in an upper portion 24a thereof. That is, the internal space of the circulating water tank 24 is opened to the atmosphere via the opening 24a1.

  A partition wall 24c is formed inside the circulating water tank 24 so as to protrude upward from the lower portion 24b of the circulating water tank 24 by a predetermined height h1. A plurality (specifically, two) chambers are formed in the circulating water tank 24 by the partition wall 24c. In the following, the chamber on the right side of the drawing is referred to as a “first chamber” and is denoted by reference numeral 24d1, and that on the left side is referred to as a “second chamber” and denoted by reference numeral 24d2.

  Both the first and second chambers 24d1 and 24d2 have a substantially rectangular shape when viewed from above, as shown in FIG. Further, the first chamber 24 d 1 and the second chamber 24 d 2 are communicated in the upper space of the circulating water tank 24. The volume of the first chamber 24d1 is set to be smaller than that of the second chamber 24d2.

  As shown in FIG. 2, the first and second communication pipes 22a and 22b described above are connected to the upper part of the circulating water tank 24 on the first chamber 24d1 side, and their end portions 22a1 and 22b1 are connected to the first part. 1 chamber 24d1. This configuration will be described in detail later.

  Returning to the description of FIG. 1, the circulating water pipe 32 is connected to the lower portion 24 b of the circulating water tank 24, more precisely, the lower portion of the circulating water tank 24 on the second chamber 24 d 2 side. That is, the second chamber 24 b 2 of the circulating water tank 24 and the reforming unit 12 a of the reformer 12 are connected via the circulating water pipe 32.

  Next, the operation or action of the fuel cell unit 10 configured as described above will be described.

  The reforming fuel supplied from the reforming fuel supply source is first heated through the reforming fuel pipe 30, the first three-way valve 46 and the heating fuel pipe 50, that is, the heating unit 12 b of the reformer 12. The fuel is supplied to the combustion burner as a heating fuel. The combustion air sucked by the combustion air pump 54 is supplied to the combustion burner of the heating unit 12b through the combustion air pipe 42.

  The reforming fuel and combustion air supplied to the combustion burner are ignited by an ignition electrode (not shown) and burned. The combustion exhaust gas generated by the combustion is discharged (exhaust) into the atmosphere through the combustion exhaust pipe 52 while heating the reforming portion 12a.

  When it is determined that the reforming unit 12a has been heated to a temperature at which the reforming unit 12a can be reformed (specifically, about 700 [° C.]) based on an output from a reforming unit temperature sensor (not shown), the reforming unit 12a The reforming operation is started. Specifically, the reforming fuel supplied from the reforming fuel supply source is supplied to the reforming unit 12 a via the reforming fuel pipe 30 and the first three-way valve 46. In addition, the circulating water in the circulating water tank 24 fed by the circulating water pump 40 is introduced into the reforming unit 12a as reforming water through the circulating water pipe 32.

  The reforming water (circulated water) that has flowed into the reforming unit 12a is evaporated by the heat from the heating unit 12b to become water vapor, which is mixed with the above-described reforming fuel to form a reforming catalyst (not shown). In this case, a steam reforming reaction occurs. That is, anode gas (gas fuel) containing hydrogen is generated from the mixed reforming fuel and water vapor.

  The produced anode gas is supplied to the anode electrode of the fuel cell 14 through the anode gas pipe 34, the second three-way valve 90, and the first steam separator 16a. The anode gas that passes through the first steam separator 16a will be described later.

  Further, the cathode gas sucked by the cathode gas pump 62 is supplied to the cathode electrode of the fuel cell 14 through the cathode gas pipe 56. The cathode gas supplied to the cathode electrode of the fuel cell 14 causes an electrochemical reaction with the anode gas supplied to the anode electrode. The electric power (DC current) generated by the fuel cell 14 by the electrochemical reaction is supplied to an electric load (external electric device) through an output terminal and an output circuit (not shown).

  The cathode offgas discharged from the fuel cell 14 is discharged into the atmosphere through the cathode offgas pipe 60. The anode gas (anode offgas) discharged from the fuel cell 14 is supplied as a heating fuel to the heating unit 12b of the reformer 12 via the anode offgas pipe 44 and the second steam separator 16b. Further, the second three-way valve 90 is operated in accordance with the operating state of the fuel cell 14, and part of the anode gas generated in the reformer 12 is also supplied to the anode gas pipe 34, the second three-way valve 90, the anode. It is supplied to the heating unit 12b of the reformer 12 through the off-gas pipe 44 and the second steam / water separator 16b.

  In the fuel cell unit 10, the first three-way valve 46 operates when the anode off gas is supplied to the heating unit 12 b, in other words, when the fuel cell unit 14 is in an operation state in which electric power is generated (during normal operation). Thus, the amount of reforming fuel supplied from the reforming fuel pipe 30 to the heating unit 12b via the heating fuel pipe 50 is gradually reduced, and finally the supply is stopped. That is, only the anode off gas (or part of the anode gas generated by the reformer 12) is supplied to the heating unit 12b during normal operation of the fuel cell unit 10.

  Next, the anode gas passing through the first steam separator 16a and the anode off-gas passing through the second steam separator 16b will be described.

  Since the anode gas flowing through the anode gas pipe 34 is generated by the steam reforming reaction as described above, it contains a large amount of moisture. Therefore, if the fuel cell 14 is supplied as it is, water clogging occurs at the inlet of the anode electrode of the fuel cell 14 and the flow of the anode gas is obstructed. Therefore, the anode gas in the anode gas pipe 34 is caused to flow into the first steam-water separator 16a, and moisture is separated from the anode gas. The water separated by the first air / water separator 16 a is caused to flow into the circulating water tank 24, more precisely, the first chamber 24 d 1 of the circulating water tank 24 through the first communication pipe 22 a.

  On the other hand, the anode off gas flowing through the anode off gas pipe 44 may contain a large amount of moisture. Therefore, if it is supplied as it is to the combustion burner of the heating unit 12b, the ignition failure of the combustion burner and the calorie loss of the combustion burner due to latent heat increase. Therefore, the anode off gas in the anode off gas pipe 44 is caused to flow into the second steam-water separator 16b, and moisture is separated from the anode off gas. The water separated by the second steam separator 16b is caused to flow into the circulating water tank 24, more precisely, the first chamber 24d1 of the circulating water tank 24 through the second communication pipe 22b.

  When the amount of moisture (circulated water) W1 supplied from the first steam separator 16a or the second steam separator 16b and stored in the first chamber 24d1 increases, as shown by an arrow A in FIG. In addition, the circulating water W1 flows over the upper end 24c1 of the partition wall 24c (overflows) to the second chamber 24d2, and is stored in the second chamber 24d2. Accordingly, the first chamber 24d1 always holds (secures) a water surface having a constant height, specifically, a water surface having a height h1. Note that the water (circulated water) W2 that has flowed out and stored from the first chamber 24d1 to the second chamber 24d2 is improved as described above when the circulating water pump 40 is operated. It is supplied to the mass part 12a.

  Here, the first communication pipe 22a disposed inside the first chamber 24d1 will be described in detail. Hereinafter, the first communication pipe 22a will be described. However, since the first and second communication pipes 22a and 22b have substantially the same configuration, the following description is also substantially applicable to the second communication pipe 22b.

  Referring to FIG. 2, in the first chamber 24d1 of the circulating water tank 24, moisture (circulating water) W1 supplied from the first and second steam / water separators 16a is supplied to the upper end 24c1 of the partition wall 24c. Is stored. The first communication pipe 22a is inserted into the circulating water W1 stored in the first chamber 24d1. That is, the end 22a1 of the first communication pipe 22a is always positioned in the circulating water W1 stored in the first chamber 24d1.

  At this time, the water surface Wsa in the first communication pipe 22a is pushed downward by the pressure of the anode gas introduced from the first steam separator 16a. More specifically, from the water surface Wsb of the circulating water W1, The pressure obtained by subtracting the atmospheric pressure from the pressure of the anode gas (inner pressure of the anode gas pipe 34, positive pressure), specifically, the head height h2 corresponding to the difference between the pressure of the anode gas and the atmospheric pressure is pushed downward. .

  Therefore, the insertion depth h3 from the water surface Wsb in the first communication pipe 22a is set to a value obtained by adding the predetermined height α to the water head height h2. That is, the end 22a1 of the first communication pipe 22a is moved from the water surface Wsb of the circulating water W1 stored in the first chamber 24d1 of the circulating water tank 24 to a head height corresponding to the difference between the pressure of the anode gas and the atmospheric pressure. It was configured to extend to a position h3 deeper than the length h2.

  Thereby, even when the pressure of the anode gas acts on the water surface Wsa in the first communication pipe 22a, the circulating water always exists in the vicinity of the lower end of the first communication pipe 22a by a predetermined height α. Therefore, the anode gas in the anode gas pipe 34 can be prevented from flowing (leaking) into the circulating water tank 24 and the like through the first communication pipe 22a.

  The cross-sectional area of the first communication pipe 22a (that is, the area of the water surface Wsa in the first communication pipe 22a) and the area of the water surface Wsb of the circulating water W1 stored in the first chamber 24d1 are the anode gas. The pressure is set appropriately in consideration of the pressure (or anode off gas) and atmospheric pressure.

  As described above, in the embodiment of the present invention, the reformer 12, the fuel cell 14 to which the gas fuel generated by the reformer is supplied, and the steam and water that separates moisture from the gas fuel. A separator (first and second steam separators 16a and 16b), and the steam separator connected to the steam separator via a communicating pipe (first and second communicating pipes 22a and 22b); In the fuel cell unit 10 including at least a circulating water tank 24 that is supplied with water separated by the cooler and stores the water as circulating water for the reformer, the circulating water tank is lowered in the gravity direction of the steam separator. In other words, the water separated by the steam separators (16a, 16b) is directly supplied (dropped) to the circulating water tank 24 through the communication pipes (22a, 22b). So moisture separated by steam separator The storage tank for temporarily storing can be made unnecessary, thus can reduce the space occupied.

  Further, the end portions (22a1, 22b1) of the communication pipes (22a, 22b) are positioned in the circulating water W1 stored in the circulating water tank 24, that is, anode gas or anode off gas is supplied to the circulating water. Since the liquid is sealed with the circulating water W1 in the tank 24, the conventional storage tank, electromagnetic valve, liquid level sensor, and the like can be dispensed with. The water in the steam separators 16a and 16b can be supplied to the circulating water tank 24 while preventing leakage of anode gas or the like. Further, since there is no electromagnetic valve or liquid level sensor as in the prior art, it is advantageous in terms of cost.

  The circulating water tank 24 includes a chamber (first chamber 24d1), and ends (22a1, 22b1) of the communication pipes (22a, 22b) are positioned in the circulating water W1 stored in the chamber. It was configured to make it. As a result, the anode gas or the anode off-gas can be sealed with a part of the circulating water stored in the circulating water tank 24, specifically, a relatively small amount of circulating water W1 stored in the first chamber 24d1. Leakage of gas and the like can be further prevented.

  The circulating water tank 24 is opened to the atmosphere, and the end portions (22a1, 22b1) of the communication pipes (22a, 22b) are separated from the water surface Wsb of the circulating water W1 stored in the circulating water tank 24. Since it is configured to extend to a position h3 deeper than the head height h2 corresponding to the difference between the pressure of the gas fuel and the atmospheric pressure, the first gas and the second gas can be prevented while further preventing leakage of anode gas and the like. The water in the water separators 16 a and 16 b can be supplied to the circulating water tank 24.

  That is, in the communication pipe (22a, 22b) in which the end portions (22a1, 22b1) are positioned in the circulating water W1 of the circulating water tank 24, the water surface Wsa of the water in the communication pipe is lowered by the pressure of the anode gas or the anode off gas. More specifically, it is pushed downward from the water surface Wsb of the circulating water W1 of the circulating water tank 24 by a head height h2 corresponding to the difference between the pressure of the anode gas or the like and the atmospheric pressure. Therefore, the end portions (22a1, 22b1) of the communication pipe are moved from the water surface Wsa of the circulating water W1 of the circulating water tank 24 to a position h3 deeper than the head height h2 corresponding to the difference between the pressure of the anode gas and the atmospheric pressure. Since it is configured to be extended, even when the pressure of the anode gas or the like acts on the water surface Wsa in the communication pipe, moisture is always present in the vicinity of the lower end of the communication pipe by a predetermined height α, Therefore, it is possible to prevent anode gas or the like from flowing into the circulating water tank 24 (leaking) through the communication pipes (22a, 22b).

  Further, since the gas fuel is composed of the anode gas, the above-described effects can be obtained in the anode gas (or anode off gas) containing a large amount of moisture.

  In the above description, the fuel cell 14 is a solid polymer type. However, the present invention is not limited to this, and other types may be used.

  Further, the shape of the circulating water tank 24 is configured to be a substantially rectangular parallelepiped, but other shapes such as a cylindrical shape may be used, and the shapes of the first and second chambers 24d1 and 22d2 are also illustrated. It is not limited to.

  In addition, although city gas is used as the reforming fuel, LP gas or the like may be used.

It is a schematic diagram for explaining a fuel cell unit according to an embodiment of the present invention. It is explanatory drawing for demonstrating the circulating water tank etc. which are shown in FIG. It is the III-III sectional view taken on the line of the circulating water tank shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell unit, 12 Reformer, 14 Fuel cell, 16a 1st steam-water separator (steam-water separator), 16b 2nd steam-water separator (steam-water separator), 22a 1st communicating pipe (Communication pipe), 22b second communication pipe (communication pipe), 22a1 (first communication pipe) end, 22b1 (second communication pipe) end, 24 circulating water tank, 24d1 first chamber (Chamber), W1 circulating water, Wsb (circulating water) water surface

Claims (4)

  A reformer, a fuel cell to which gas fuel generated by the reformer is supplied, a steam separator for separating water from the gas fuel, and a steam pipe connected to the steam separator. A fuel cell unit provided with at least a circulating water tank that is supplied with the water separated by the steam separator and stores it as circulating water for the reformer, wherein the circulating water tank is the gravity of the steam separator. A fuel cell unit, wherein the fuel cell unit is arranged at a lower side in a direction, and an end of the communication pipe is positioned in circulating water stored in the circulating water tank.   2. The fuel cell unit according to claim 1, wherein the circulating water tank includes a chamber and is configured so that an end of the communication pipe is positioned in the circulating water stored in the chamber.   The circulating water tank is opened to the atmosphere, and the end of the communication pipe is separated from the surface of the circulating water stored in the circulating water tank by a head height corresponding to the difference between the pressure of the gas fuel and atmospheric pressure. The fuel cell unit according to claim 1, wherein the fuel cell unit is configured to extend to a deep position.   The fuel cell unit according to any one of claims 1 to 3, wherein the gas fuel is an anode gas.

Images