JP2012128988A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system that can always supply only clean pure water to a fuel cell even when impurities such as water stain and dirt are contained in a pure water tank.SOLUTION: A tip opening 122 of a water intake pipe 12 made of a bellows tube is opened sideways, and a float member 131 is mounted on the tip opening 122 as in this state by a connecting member 132. Thus, the tip opening 122 is maintained in a position at a certain distance beneath the surface of pure water. A pedestal 14 protruding downward for a predetermined distance is mounted on the tip opening 122 so that the tip opening is controlled not to sink beyond a position at a certain distance above from a bottom face 104 even when the water level is lowered. In this manner, impurities floating on the water surface as well as impurities deposited on the bottom face 104 are prevented from being sucked into the tip opening 122.

Description

  The present invention relates to a fuel cell system, and particularly relates to a fuel cell system including a pure water tank that stores pure water used for steam reforming.

  Conventionally, as pure water used for steam reforming, for example, drain water generated in the process of heat recovery from exhaust gas generated in a reformer is generated by water treatment and stored in a pure water tank. The use of a predetermined amount is performed. The pure water in the pure water tank is taken out by a predetermined amount by operating a pure water supply pump.

  Although it is not intended for a pure water tank, for example, in Patent Document 1, a fuel tank for storing fuel for a fuel cell and a water tank for supplying water to the fuel tank are each supplied with fuel and water. A liquid suction tube for sucking liquid is arranged in each tank, while a gas discharge tube for taking out gas such as carbon dioxide gas from the upper part of the fuel tank and discharging it into the water tank is provided in each tank. In the arrangement, it has been proposed that the tip of each tube automatically changes its position in preparation for a change in posture of each tank (for example, upside down). In this device, a weight is attached to the tip of the liquid suction tube, while a float is attached to the tip of the gas discharge tube.

  Similarly, although not intended for a pure water tank, in Patent Document 2, for example, in a fuel tank for storing fuel for a fuel cell, a supply pipe for taking out the stored fuel and supplying it to the fuel cell In order to maintain the tip of the liquid in the fuel tank regardless of whether the liquid level in the fuel tank is vertically changed or inclined, the liquid immersion means comprising a float and a weight is provided in the supply pipe. It is also proposed to install at the tip of

Japanese Patent Application Laid-Open No. 2008-159592 JP 2007-335144 A

  By the way, if impurities such as scale and dust are mixed in the pure water stored in the pure water tank, for example, when the pure water is supplied to the power generation module, the water supply pump is clogged, or measurement with a flow meter is performed. It may cause an error, and eventually the water supply pump may stop or the flow rate may not be measured by the flow meter. Furthermore, there is a possibility that the fuel cell may be deteriorated due to a shortage of supply amount of pure water generated due to clogging or the like, or as a result, the power generation capacity may be reduced.

  The present invention has been made in view of such circumstances, and the purpose of the present invention is to always provide only pure water, even if impurities such as scale and dust are mixed in the pure water tank. It is to provide a fuel cell system that can supply a fuel cell to a fuel cell.

  In order to achieve the above object, in the present invention, the raw fuel is reformed into hydrogen-rich fuel gas by steam reforming, and the fuel gas is supplied to the anode, while the oxygen-containing gas is supplied to the cathode to generate power. The deionized water is stored in the deionized water tank for use in the steam reforming, and the deionized water is taken from the deionized water tank by the operation of the water supply pump and supplied to the evaporator. The following specific items are provided for the fuel cell system that is being used. That is, the pure water tank is provided with a water intake pipe for taking the pure water stored therein from the front end opening, and holding means for holding the front end opening of the water intake pipe at a predetermined position in relation to the surface of the pure water. I did it. The intake pipe is configured to be movable so as to follow fluctuations in the level of pure water in the pure water tank, and the tip opening is maintained in the water at a certain distance below the surface of the pure water as the holding means. (Claim 1).

  In the case of the present invention, even if the pure water level fluctuates up and down, the tip opening of the intake pipe can move up and down in conjunction with the fluctuation, and is always held by the holding means. The tip opening is maintained at a certain distance below the surface of pure water. For this reason, even if impurities such as scale and dust are floating on the water surface, it is possible to avoid inhaling the floating impurities and even if the impurities are attached to the inner surface of the pure water tank. It is possible to avoid sucking the adhering impurities. As described above, it is possible to always supply clean pure water free of impurities to the evaporator or the fuel cell side. As a result, it is possible to reliably avoid the situation that the water supply pump is stopped or the flow rate cannot be measured by the flow meter, which is assumed when impurities are mixed in the pure water supplied from the pure water tank. Furthermore, there is no possibility that the fuel cell will be deteriorated due to insufficient supply of pure water caused by clogging or the like, or that the power generation capacity will be lowered as a result.

  The holding means in the present invention may be configured such that the tip opening of the intake pipe is maintained laterally open in water (Claim 2). By doing in this way, compared with the case where the tip opening is opened upward, it is possible to more reliably avoid the floating impurities on the water surface being sucked into the tip opening.

  Further, as the holding means in the present invention, when pure water is sucked from the tip opening of the water intake pipe by the operation of the water supply pump, the water surface is constant so that impurities floating on the pure water surface do not flow into the tip opening. It can be set as the structure which maintains the said front-end | tip opening at distance (Claim 3). By doing so, it is possible to more reliably avoid the floating impurities on the water surface from being sucked into the tip opening.

  Further, the intake pipe or the holding means of the present invention may be provided with a restricting means for restricting the tip opening of the intake pipe so as not to settle below a predetermined distance above the bottom surface of the pure water tank. 4). By doing so, even if the water level is remarkably lowered and the pure water level is lowered to near the bottom surface of the pure water tank, the tip opening is always held at a position above the bottom surface by the restricting member. Therefore, even if impurities such as water scale and dust are precipitated on the bottom surface, it is possible to avoid sucking the precipitated impurities.

  As described above, according to the fuel cell system of the present invention, even if the pure water level fluctuates in the pure water tank, the tip opening of the intake pipe is moved up and down in conjunction with the fluctuation. In addition, it is held by the holding means, and the tip opening can always be maintained at a certain distance below the surface of the pure water. For this reason, even if impurities such as scale and dust are floating on the water surface, it is possible to avoid inhaling the floating impurities and that the impurities are attached to the inner surface of the pure water tank. However, it becomes possible to avoid sucking the adhering impurities. As described above, it becomes possible to always supply clean pure water free of impurities to the evaporator or the fuel cell side. As a result, it is possible to reliably avoid a situation in which the water supply pump is stopped or the flow rate cannot be measured by the flow meter, which is assumed when impurities are mixed in the pure water supplied from the pure water tank. It is possible to eliminate the risk of deteriorating the fuel cell due to a shortage of the amount of pure water generated due to clogging or the like, or resulting in a decrease in power generation capacity.

  In particular, according to the second aspect, by maintaining the tip opening of the intake pipe in a state of being opened sideways in the water by the holding means, the floating impurities on the water surface are formed in the tip opening compared to the case where the tip opening is opened upward. Inhalation can be avoided more reliably.

  According to the third aspect of the present invention, the holding means maintains the tip opening of the intake pipe at a certain distance below the surface of the water so that impurities floating on the pure water surface do not flow into the tip opening. Avoidance of floating impurities being sucked into the tip opening can be realized more reliably.

  Further, according to the fourth aspect of the present invention, the water intake pipe or the holding means is provided with a restricting means for restricting the opening of the tip of the water intake pipe from being settled below a predetermined distance from the bottom surface of the pure water tank. Even if the water level drops to near the bottom surface of the pure water tank, the restriction member can always hold the tip opening at a position above the bottom surface by a predetermined distance or more. Even if it is precipitated, it is possible to avoid sucking the precipitated impurities.

It is a mimetic diagram showing an embodiment of a fuel cell system of the present invention. It is an expansion explanatory view of a 1st embodiment as a pure water tank of Drawing 1. 3A is an enlarged cross-sectional explanatory view taken along line AA in FIG. 2, and FIG. 3B is a cross-sectional explanatory view when the inside of the pure water tank as an example is viewed in a planar state. FIG. 3 is a view corresponding to FIG. 2 of a pure water tank according to a second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example using a solid oxide fuel cell (SOFC) as a fuel cell system according to an embodiment of the present invention. Reference numeral 4 in the figure denotes a battery body (power generation module). The battery body 4 includes a cell stack 41, a reformer 42, and an air heat exchanger 43. The supply of fuel gas, air, water vapor, etc. to the battery body 4 and the discharge of exhaust gas are all performed through the preheater / evaporator 5. A fuel gas circuit 6, a reforming air supply circuit 7 and a cathode air supply circuit 8 are passed through the preheating / evaporator 5, while exhaust gas is introduced from the battery body 4 side as a heat source for preheating, and thereafter The pure water derived from the water supply processing circuit 9 and obtained by recovering the moisture in the exhaust gas is returned to the fuel gas circuit 6 in the preheater / evaporator 5 and converted into steam for steam reforming. .

  The cell stack 41 is configured such that a plurality of cells are erected with a predetermined interval, and each cell has, for example, a small-diameter cylindrical anode (fuel electrode) and a large-diameter cylindrical shape covering the outer peripheral side. The cathode (air electrode) is integrated concentrically with an electrolyte in between. The anode and the cathode are both made of ceramics containing a metal oxide such as Ni, and the electrolyte is made of a solid oxide such as YSZ (yttrium stabilized zirconia).

  From the reformer 42, the fuel gas made richer in hydrogen than the raw fuel fuel gas is flowed from the lower end toward the upper end from the reformer 42 to the inner hole of the anode of the cell. Cathode air as an oxygen-containing gas is supplied from the heat exchanger 43. At the cathode, oxygen in the cathode air becomes oxygen ions and passes through the electrolyte. At the anode, it reacts with hydrogen in the fuel gas to produce water (water vapor), and the electrons generated at that time move to the cathode side through the circuit. Electricity is generated by repeatedly ionizing oxygen again. After the fuel gas supplied to the inner hole of the anode is used for the above reaction, it is led to the reformer burner as an off gas and used as a fuel for combustion. The cathode air is exhausted upward and sent to the preheater / evaporator 5 as exhaust gas together with the combustion exhaust gas from the reformer burner. At that time, the exhaust gas passes through the air heat exchanger 43 as a heat source for heating the air.

  The fuel gas circuit 6 is provided with a regulating valve 61 composed of an original gas solenoid valve, a governor, and the like, a buffer tank 62, a gas flow sensor 63, a desulfurizer 64, a check valve 65, and the like, so The reforming air supply circuit 7 joins before entering. The reforming air supply circuit 7 includes a reforming air blower 71 that sucks and sends the air through a filter (not shown), a buffer tank 72, a reforming air flow sensor 73, a check valve 74, and the like. And are intervened. The fuel gas circuit 6 joined with the reforming air supply circuit 7 is supplied with pure water from the water supply processing circuit 9 in the preheating / evaporator 5, and the pure water is supplied to the fuel gas circuit 6 in the preheating / evaporator 5. It is sent to the reformer 42 in a state of being evaporated into water vapor. Similarly to the reforming air supply circuit 7, the cathode air supply circuit 8 sucks the atmosphere through a filter (not shown) and supplies it as an oxygen-containing gas, a buffer tank 82, and cathode air A flow sensor 83 and the like are interposed.

  The water supply processing circuit 9 is configured to recover water contained in the exhaust gas after passing through the preheater / evaporator 5, purify the collected condensed water (drain water), store purified water after purification, and store the purified water. In this circuit, water is supplied to the preheater / evaporator 5 in order to reuse water as water vapor. The water supply processing circuit 9 shown in FIG. 1 is an exemplification. The water supply processing circuit 9 in this figure temporarily receives the heat exchanger 91 for exhaust heat recovery and the condensed water collected by the heat exchanger 91. A drain recovery device 92 to be stored, a water treatment device 93 that performs a pH adjustment process of the condensed water of the drain recovery apparatus 92, a purification process for purifying to pure water by a reverse osmosis membrane (RO membrane), an ion exchange membrane, and the like; Pure water tank 94 for storing purified water after purification and pure water for taking pure water from the pure water tank 94 and supplying it to the preheating / evaporator 5 side at a constant flow rate (for example, 4 to 6 mL / min flow rate). A water pump 95, a pure water flow rate sensor 96 for detecting the pure water flow rate at that time, and a check valve 97 are sequentially provided from the upstream side. The pure water supplied from the water supply processing circuit 9 to the preheater / evaporator 5 is evaporated by the preheater / evaporator 5 to form water vapor and supplied to the reformer 42 and the anode side of the battery body 4. .

  The exhaust heat recovery heat exchanger 91 recovers the latent heat of the exhaust gas after the sensible heat recovery by the preheater / evaporator 5 to recover the water circulated from the circulation circuit on the hot water storage unit side, for example, outside the figure. Heat exchange is heated. As a result, heat recovery from the exhaust gas of the fuel cell is achieved, and the recovered heat is stored in the hot water storage tank in the form of hot water, and the stored hot water is used for hot water supply, filling of the bathtub, etc. It has become.

  Hereinafter, the pure water tank 94 which is a characteristic part of the present embodiment will be described in detail. That is, as shown in detail in FIG. 2, the pure water tank 94 has a water level detecting means 11 for detecting the stored water level inside the tank body 10 having the water inlet 101, the outlet 102 and the overflow port 103. And a movable intake pipe 12 that collects pure water inside and discharges the pure water from the discharge port 102.

  The water level detection means 11 includes a guide rod 111 and a plurality of float members 112, 113, 114 that are guided by the guide rod 111 to move up and down over a predetermined range. Each float member 112, 113, 114 has a built-in proximity switch, and moves up and down following the vertical fluctuation of the pure water level PL, so that each float member 112, 113, 114 moves to a predetermined water level position in the vertical range set as the respective defense range. When it reaches, the proximity switch is turned ON and output to a controller (not shown).

  The intake pipe 12 is configured to be movable by, for example, a rubber flexible tube or a bellows pipe, and the base end 121 is connected so as to communicate with the discharge port 102, and the distal end opening 122 is submerged in water so that a predetermined level in the water is reached. It is opened sideways while being maintained in position. At the tip of the intake pipe 12, there is a holding means 13 that keeps the tip opening 122 maintained at a fixed position below the surface of the pure water stored, and the tip even if the pure water level PL drops significantly. Limiting means 14 for limiting the settling to a position away from the bottom surface 104 by a certain distance without being seated on the bottom surface 104 of the tank body 10 is mounted.

  As shown in FIG. 3A, the holding means 13 includes a float member 131 and a connecting member 132 that connects the distal end portion of the intake pipe 12 to a relative position below the float member 131 by a predetermined distance. ing. The buoyancy of the float member 131 is set so that the tip opening 122 can be maintained at a predetermined position below the water surface, against the fact that the tip portion of the float member 131 tends to sink due to its own weight. As long as the connecting member 132 can hold the float member 131 and the tip of the intake pipe 12 in a predetermined relative positional relationship, various connecting members can be adopted. A bracket attached to the intake pipe 12 so as to surround the outer periphery of the tip portion thereof is fixed to the attachment portion on the float member 131 side by a bolt / nut means.

  The restricting means 14 may be employed regardless of its shape or the like as long as it is a spacer that protrudes downward by a predetermined dimension from the tip of the intake pipe, but the illustrated means is the holding means 13 or the intake pipe 12. A pedestal is attached as a spacer to the front end portion (the front end portion of the intake pipe 12 in the illustrated example).

  As described above, the front end opening 122 of the intake pipe 12 is held at a position away from the water surface position of the pure water level PL by a predetermined distance S (see FIG. 3A), and when the water level is lowered, It can be held at a position away from the bottom surface 104 position by a predetermined distance T or more. As described above, if the suction flow rate from the tip opening 122 is extremely small (for example, 4 to 6 mL / min), the predetermined distance S is 1.5 to 2. A value of 0 times may be set. For example, when the inner diameter D of the tip opening 122 is 8 to 10 mm, S = 1.5D to 2.0D, and S = 12 to 20 mm may be set.

  In this embodiment, the tip opening 122 of the intake pipe 12 moves up and down in conjunction with the fluctuation of the pure water level PL even if the pure water level PL fluctuates, and the tip opening 122 always has the pure water level. It will be maintained in the state opened sideways toward the water at the position below the surface S of the PL. For this reason, even if impurities such as scale and dust are floating on the water surface, it is possible to avoid inhaling the floating impurities, and the impurities adhere to the inner surface 105 of the tank body 10. Even so, it is possible to avoid sucking the adhering impurities. Moreover, such an effect can be obtained without change even if the pure water level fluctuates. Further, even if the water level is remarkably lowered and the pure water level PL is lowered to the vicinity of the bottom surface 104 of the tank body 10, the front end opening 122 is always more than the bottom surface 104 by the predetermined distance T by the seating of the limiting member 14 on the bottom surface 104. It can hold | maintain in the above upper position. For this reason, even if impurities such as scale and dust are precipitated on the bottom surface 104, it is possible to avoid sucking the precipitated impurities. As described above, it is possible to always supply clean pure water free from impurities to the fuel cell side. As a result, it is possible to reliably avoid a situation in which the water supply pump is stopped or the flow rate cannot be measured by the flow meter, which is assumed when impurities are mixed in the pure water supplied from the pure water tank. There is no possibility of causing deterioration of the fuel cell due to insufficient supply of pure water due to clogging or the like, or as a result, causing a decrease in power generation capacity.

  The pure water tank 94 has a relatively low flow rate of both pure water inflow and water intake, and the pure water tank 94 is maintained in a state where there is almost no influence by the flow of pure water. However, the horizontal direction of the float member 131 of the holding means 13 is maintained. As a measure for suppressing blurring, for example, as shown in FIG. 3B, the lateral width of the float member 13 may be set to be slightly smaller than the inner width of the tank body 10. By doing in this way, the lateral blurring of the float member 131 can be suppressed to a limited one.

Second Embodiment
FIG. 4 shows a pure water tank 94 according to the second embodiment. The pure water tank 94 according to the second embodiment is one in which the float member 131 of the holding means 13 is also used as the float member of the water level detection means 11a. About the thing of the same structure as 1st Embodiment, the code | symbol same as 1st Embodiment is attached | subjected and the overlapping description is abbreviate | omitted, and below, mainly a different point is demonstrated.

  In the second embodiment, the float member 131 of the holding means 13 is engaged with the guide rod 115 of the water level detection means 11a so as to be movable up and down, and the float member 131 moves up and down in conjunction with fluctuations in the pure water level PL. As a result, the water level can be detected by the proximity switch built in the float member 131, and the tip opening 122 of the water intake pipe 12 is held at a position at a distance below the water surface S (see FIG. 3A). Yes.

  In the illustrated example, the guide rod 115 of the water level detecting means 11a extends obliquely between the top surface and the bottom surface of the tank body 10 in consideration of the vertical movement characteristics of the tip opening 122 of the intake pipe 12 constituted by a bellows pipe. However, the present invention is not limited to this, and it is sufficient that the intake pipe 12 has flexibility that can accompany the vertical movement of the float member 131, and the guide rod 115 is attached in the vertical direction. May be.

  In the case of the second embodiment described above, the same effect as that of the first embodiment can be obtained, and the limiting means of the first embodiment can be provided by providing a stopper 116 at a predetermined position below the guide rod 115, for example. 14 can be accomplished, and the stopper 116 can be simply configured by the stopper 116.

<Other embodiments>
The present invention is not limited to the first and second embodiments, but includes various other embodiments. That is, in the first and second embodiments, the example in which the fuel cell system is configured by using the SOFC is shown. However, if the fuel cell system includes a pure water tank in order to use pure water, the present invention may be used. It can be applied and is included in the present invention.

  Further, in the first and second embodiments, the intake pipe 12 has a substantially full length constituted by a bellows pipe. However, the intake pipe 12 is not limited to this, and is flexible enough to follow fluctuations in the water level. It suffices if it is provided or configured to be able to bend so that it can follow fluctuations in the water level. In short, it should be configured to be movable so as to follow the fluctuation of the water level.

4 Battery body 5 Preheating / evaporator (evaporator)
DESCRIPTION OF SYMBOLS 10 Tank main body 12 Intake pipe 13 Holding means 14 Restriction means 42 Reformer 94 Pure water tank 116 Stopper (restriction means)
122 Tip opening 131 Float member

Claims (4)

The raw fuel is reformed into hydrogen-rich fuel gas by steam reforming, and the fuel gas is supplied to the anode, while the oxygen-containing gas is supplied to the cathode to generate power, which is used for the steam reforming. In order to do so, a pure water tank is a fuel cell system configured to store pure water from a pure water tank by an operation of a water supply pump and supply the pure water to an evaporator,
The pure water tank includes a water intake pipe for taking pure water stored therein from a front end opening, and holding means for holding the front end opening of the water intake pipe in a predetermined position in relation to the water surface of the pure water,
The intake pipe is configured to be movable so as to follow fluctuations in the level of pure water in the pure water tank, while the holding means maintains the tip opening at a certain distance below the surface of the pure water. It is configured,
A fuel cell system. The fuel cell system according to claim 1,
The fuel cell system is configured such that the holding means is configured to maintain the tip opening of the intake pipe in a state of being opened sideways in water. The fuel cell system according to claim 1 or 2, wherein
When the pure water is sucked from the tip opening of the water intake pipe by the operation of the water supply pump, the holding means has the tip at a certain distance below the surface of the water so that impurities floating on the pure water surface do not flow into the tip opening. A fuel cell system configured to maintain an opening. The fuel cell system according to any one of claims 1 to 3,
A fuel cell system, wherein the intake pipe or the holding means is provided with restricting means for restricting the leading end opening of the intake pipe so as not to settle below a predetermined distance above the bottom surface of the pure water tank.

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