JP2008078018A - Fuel cell system and humidifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of suppressing partial deterioration of a hollow fiber bundle and to provide a humidifier. <P>SOLUTION: The fuel cell system is provided with a fuel cell to generate power by a chemical reaction of an oxidizing gas and a fuel gas and the humidifier A21 to humidify at least one of the oxidizing gas and the fuel gas. The humidifier A21 has the hollow fiber bundle 102 and a body 103 in which through holes 104 being inlet holes of humidified gas or humidifying gas circulating respectively through the inner and the outer circumference of the hollow fiber bundle 102 are formed. The body 103 in which the through holes 104 are formed is installed so as to be able to change the relative positions with the hollow fiber bundle 102. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system that generates electric power by an electrochemical reaction between an oxidizing gas and a fuel gas, and more particularly to a humidifier that adds moisture to air supplied to a fuel cell.

Some conventional fuel cell systems include a humidifier that adds required moisture to air in an air supply path for supplying air (external air) as an oxidizing gas to an air supply port of the fuel cell. As a humidifier, what has a humidification module which has a hollow fiber bundle which consists of many hollow fibers in the inside, and a body which surrounds the circumference of a hollow fiber bundle is known (for example, refer to the following patent documents 1). . An air supply hole for supplying air to the hollow fiber bundle and an air discharge hole for discharging air supplied to the hollow fiber bundle are formed in the body of the humidification module (housing in Patent Document 1). Yes.
JP 2005-155994 A

  By the way, in the conventional humidifier, both the hollow fiber bundle and the body are fixed, and the relative positional relationship between them does not change. Therefore, the part corresponding to the air supply hole in the hollow fiber bundle is always the same, and the supply air directly hits the part corresponding to the air supply hole, so that mechanical and chemical stress acts more than the other parts. To do. As a result, a portion corresponding to the air supply hole is locally deteriorated.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel cell system and a humidifier that can suppress partial deterioration of a hollow fiber bundle.

  In order to achieve the above object, a fuel cell system according to the present invention comprises a fuel cell that generates power by an electrochemical reaction between an oxidizing gas and a fuel gas, and humidifies at least one of the oxidizing gas and the fuel gas supplied to the fuel cell. A hollow fiber capable of exchanging moisture between a humidified gas flowing through one of the inner and outer peripheries and a humidified gas flowing through the other humidifier. And a body that covers an outer periphery of the bundle of hollow fibers and has an introduction hole through which the humidified gas or the humidified gas is introduced in the outer periphery, and the introduction of the bundle of hollow fibers. The relative position between the portion corresponding to the hole and the introduction hole is variable.

  Further, the humidifier of the present invention includes a bundle of hollow fibers capable of moisture exchange between a humidified gas flowing through one of the inner and outer circumferences and a humidified gas flowing through the other, and the outer circumference of the bundle of hollow fibers And a body in which an introduction hole for introducing the humidified gas or the humidified gas is formed through the outer periphery of the bundle, and a portion corresponding to the introduction hole in the bundle of hollow fibers and the body The relative position to the introduction hole is variable.

  According to the above configuration, since at least one of the bundle of hollow fibers and the introduction hole is provided such that the relative position with respect to the other is variable, at least one of the bundle of hollow fibers and the introduction hole is provided. Is displaced, the portion of the bundle of hollow fibers corresponding to the introduction hole moves. As a result, the portion where the humidified gas or humidified gas supplied from the introduction hole directly hits the hollow fiber is not fixed, so that only a specific portion of the bundle of hollow fibers is prevented from being intensively deteriorated.

  In the present invention, at least one of the bundle of hollow fibers and the introduction hole may be driven by electric power of a fuel cell that generates electric power using a humidified gas humidified by the humidifier. Accordingly, a mechanism for suppressing partial deterioration of the bundle of hollow fibers can be completed in the fuel cell system.

  In the present invention, the bundle of hollow fibers and the body formed with the introduction hole are provided coaxially, and at least one of the bundle of hollow fibers and the introduction hole is centered on the axis, The humidifier may be rotated relative to the other, and according to this configuration, the humidifier is compared with a case where at least one of the bundle of hollow fibers and the body move relatively along the axis. Increase in size can be suppressed.

  According to the fuel cell system and the humidifier of the present invention, the partial deterioration of the hollow fiber bundle can be suppressed, and as a result, the durability of the entire humidifier can be improved.

  Next, an embodiment of a fuel cell system according to the present invention will be described. Hereinafter, the case where this fuel cell system is applied to an in-vehicle power generation system of a fuel cell vehicle will be described. However, the present invention is not limited to such an application example, and is applicable to any moving body such as a ship, an aircraft, a train, and a walking robot. For example, the present invention can be applied to a stationary power generation system in which a fuel cell is used as a power generation facility for a building (house, building, etc.).

  In the fuel cell system 1 shown in FIG. 1, air (outside air, humidified gas) as an oxidizing gas is supplied to an air supply port of the fuel cell 20 via an air supply path 71. The air supply path 71 is provided with an air filter A1 that removes particulates from the air, a compressor A3 that pressurizes the air, and a humidifier A21 that adds required moisture to the air. The air filter A1 is provided with an air flow meter (flow meter) (not shown) that detects the air flow rate. The compressor A3 is driven by a motor. This motor is driven and controlled by a control unit 50 described later. The structure of the humidifier A21 will be described later.

  Air off-gas (oxidation off-gas, humidified gas) discharged from the fuel cell 20 is discharged to the outside through the exhaust path 72. The exhaust path 72 is provided with a pressure adjustment valve A4 and a humidifier A21. The pressure adjustment valve A4 functions as a pressure regulator (pressure reduction) that sets the air pressure supplied to the fuel cell 20. The control unit 50 sets the supply air pressure and the supply air flow rate to the fuel cell 20 by adjusting the rotation speed of the motor that drives the compressor A3 and the opening area of the pressure adjustment valve A4.

  Hydrogen gas as the fuel gas is supplied from the hydrogen supply source 30 to the hydrogen supply port of the fuel cell 20 through the hydrogen supply path 74. The hydrogen supply source 30 corresponds to, for example, a high-pressure hydrogen tank, but may be a so-called fuel reformer, a hydrogen storage alloy, or the like.

  In the hydrogen supply path 74, a shutoff valve H100 that supplies or stops supplying hydrogen from the hydrogen supply source 30, a hydrogen pressure regulating valve H9 that adjusts the supply pressure of hydrogen gas to the fuel cell 20 by reducing the pressure, and the fuel cell 20 A shutoff valve H21 for opening and closing between the hydrogen supply port and the hydrogen supply path 74 is provided. As the hydrogen pressure regulating valve H9, for example, a pressure regulating valve that performs mechanical pressure reduction can be used. However, a valve whose opening degree is linearly or continuously adjusted by a pulse motor may be used.

  The hydrogen gas that has not been consumed in the fuel cell 20 is discharged as hydrogen offgas (fuel gas offgas) to the hydrogen circulation path 75 and returned to the downstream side of the hydrogen pressure regulating valve H9 in the hydrogen supply path 74. The hydrogen circulation path 75 includes a gas-liquid separator H42 that recovers moisture from the hydrogen off-gas, a drain valve H41 that recovers the recovered product water in a tank (not shown) outside the hydrogen circulation path 75, and a hydrogen pump that pressurizes the hydrogen off-gas. H50 is provided.

  The shut-off valve H21 closes the anode side of the fuel cell 20. The operation of the hydrogen pump H50 is controlled by the control unit 50. The hydrogen off-gas merges with the hydrogen gas in the hydrogen supply path 74 and is supplied to the fuel cell 20 for reuse. The shut-off valve H21 is driven by a signal from the control unit 50.

  The hydrogen circulation path 75 is connected to the exhaust path 72 on the downstream side of the humidifier A21 by the purge flow path 76 via the discharge control valve H51. The discharge control valve H51 is an electromagnetic shut-off valve, and operates according to a command from the control unit 50, whereby the hydrogen off-gas is discharged (purged) together with the air off-gas discharged from the fuel cell 20. By performing this purge operation intermittently, it is possible to prevent a cell voltage from being lowered due to an increase in the impurity concentration in the hydrogen gas.

  A cooling path 73 for circulating the cooling water is provided at the cooling water inlet / outlet of the fuel cell 20. The cooling path 73 is provided with a radiator (heat exchanger) C2 that radiates heat of the cooling water to the outside, and a pump C1 that pressurizes and circulates the cooling water. The radiator C2 is provided with a cooling fan C13 that is rotationally driven by a motor.

  The fuel cell 20 is configured as a fuel cell stack in which a required number of single cells that receive supply of hydrogen gas and air and generate electric power through an electrochemical reaction are stacked. The electric power generated by the fuel cell 20 is supplied to a power control unit (not shown). The power control unit consists of an inverter that supplies electric power to the drive motor of the vehicle, an inverter that supplies electric power to various auxiliary devices such as a compressor motor and a hydrogen pump motor, A DC-DC converter or the like that supplies power to the motors from the power storage means is provided.

  The control unit 50 is configured by a control computer system having a known configuration such as a CPU, ROM, RAM, HDD, input / output interface, display, and the like, and a required load such as an accelerator signal of a vehicle (not shown) and each part of the fuel cell system 1 Control information is received from these sensors (pressure sensor, temperature sensor, flow sensor, output ammeter, output voltmeter, etc.), and the operation of valves and motors in each part of the system is controlled.

  As shown in FIGS. 2 and 3, the humidifier A <b> 21 is discharged outside from the compressor A <b> 3 to the fuel cell 20 through the air supply path 71 (humidified gas) and from the fuel cell 20 through the exhaust path 72. Moisture exchange is performed with air off-gas (humidified gas) to add moisture to the air. As shown in FIG. 2, the humidifier A <b> 21 includes a humidification module 100 and a casing 120 that houses the humidification module 100.

  The humidification module 100 includes a hollow fiber bundle 102 in which a large number of hollow fibers 101 are bundled, and a cylindrical body 103 that surrounds the periphery of the hollow fiber bundle 102. The body 103 that covers a part of the outer periphery of the hollow fiber bundle 102 is arranged such that the central axis of the body 103 coincides with the central axis in the length direction of the hollow fiber bundle 102. In addition, a slight gap is provided between the hollow fiber bundle 102 and the body 103 so that they do not interfere with each other.

  The hollow fiber bundle 102 is arranged inside a cylindrical casing 120 whose both ends are closed so that the central axis of the hollow fiber bundle 102 coincides with the central axis of the casing 120. And between the outer surface near one end of the hollow fiber bundle 102 and the inner surface of the casing 120, the resin 130 is filled in an endless belt shape along the circumferential direction, and close to the other end of the hollow fiber bundle 102. Similarly, between the outer side surface and the inner side surface of the casing 120, the resin 131 is filled in an endless belt shape along the circumferential direction, and the filled resin 130, 131 is cured, whereby the casing 120 has a hollow fiber bundle. 102 is fixed.

  An air inlet 121 for introducing the air supplied from the compressor A3 is formed on one end wall of the casing 120, and the humidified air is directed toward the fuel cell 20 on the other end wall. The air inlet 121 and the air outlet 122 in which the air outlet 122 for leading out is formed are formed near the peripheral wall, not in the center of each end wall of the casing 120. In addition, the air inlet 121 is formed at a position shifted from the air outlet 122 by approximately a half circumference of the casing 120.

  Also, on the peripheral wall of the casing 120, there are an air off-gas inlet 123 for introducing the air off-gas discharged from the fuel cell 20, and an air off-gas outlet 124 for deriving the air off-gas used for moisture exchange. Is formed. The air off-gas inlet 123 is formed closer to the center in the length direction of the casing 120 than the one resin 130 to which the hollow fiber bundle 102 is fixed, and the air off-gas outlet 124 is fixed to the hollow fiber bundle 102. It is formed closer to the center in the length direction of the casing 120 than the other resin 131. Further, the air off-gas inlet 123 is formed at a position shifted from the air off-gas outlet 124 by approximately a half circumference of the casing 120.

  The internal space of the casing 120 is divided into three parts by the two resins 130 and 131 filled endlessly as partition walls. A space where one end of the hollow fiber bundle 102 is exposed and the air introduction port 121 is opened constitutes an air introduction chamber 125, and the other end of the hollow fiber bundle 102 is exposed and a space where the air outlet port 122 is opened. Constitutes the air outlet chamber 126. In addition, a space in which a portion excluding both ends of the hollow fiber bundle 102 is exposed, and a space where the air off-gas inlet 123 and the air off-gas outlet 124 are opened constitutes an air off-gas chamber 127.

  The body 103 is disposed in the air off-gas chamber 127 inside the casing 120 together with the hollow fiber bundle 102. The body 103 is not fixed to the two resins 130 and 131 filled between the hollow fiber bundle 102 and the casing 120, and the peripheral edges at both ends rotate in the circumferential direction between the cured resin 130 and the resin 131. It is supported freely. That is, the body 103 does not receive a large resistance from the hollow fiber bundle 102, the casing 120, and the cured resins 130 and 131, and can freely rotate around the hollow fiber bundle 102.

  A plurality of through holes (introduction holes) 104 are formed in the circumferential wall of the body 103 so as to form a line spaced apart at equal intervals in the circumferential direction. Two rows of the plurality of through holes 104 are provided so as to be separated in the length direction of the body 103. Each through-hole 104 is circular, and all the sizes thereof are the same.

  The casing 120 is provided with a drive unit 140 that rotates the body 103. The drive unit 140 includes a conversion mechanism 141 that converts the rotational movement of the body 103 around the hollow fiber bundle 102 into a shaft rotation using a mechanism such as a rack and pinion, and a motor 142 that rotates the shaft of the conversion mechanism 141. It has. The motor 142 is driven by the electric power generated by the fuel cell 20 and is controlled by the control unit 50.

  In the humidifier A <b> 21 configured as described above, dried air (humidified gas) is introduced into the air introduction chamber 125 of the casing 120 through the air introduction port 121. The air introduced into the air introduction chamber 125 is pushed into the small holes of a number of hollow fibers 101 exposed at one end of the hollow fiber bundle 102 by the pressurizing action of the compressor A3, flows inside the hollow fibers 101, and passes through the hollow fibers. It flows out from the other end of the bundle 102.

  On the other hand, an air off gas (humidified gas) containing a large amount of moisture discharged from the fuel cell 20 is introduced into the air off gas chamber 127 of the casing 120 through the air off gas introduction port 123. The air off-gas introduced into the air off-gas chamber 127 flows into the hollow fiber bundle 102 (the gap between the dense hollow fibers 101) through some of the plurality of through holes 104 formed in the body 103, and is formed in the body 103. The hollow fiber bundle 102 flows out through some of the plurality of through holes 104.

  At this time, as described above, since the body 103 changes the relative position with the hollow fiber bundle 102, the through hole 104 into which the air off-gas flows and the portion of the hollow fiber bundle 102 corresponding to the through hole 104 are fixed. Similarly, the through hole 104 through which the air off-gas flows out and the portion of the hollow fiber bundle 102 corresponding to the through hole 104 are not fixed. Even when the body 103 moves, the amount of air off-gas flowing into the hollow fiber bundle 102 before and after the body 103 does not change and is always constant.

  In the humidification module 100, the moisture contained in the moist air off-gas permeates through the membrane of the hollow fiber 101 depending on the vapor pressure difference with the dry air, and the permeated moisture is given to the dry air. Air is humidified. The humidified air flows into the air outlet chamber 126 and is discharged from the humidifier A21 through the air outlet 122. The air off gas from which moisture has been removed is discharged from the humidifier A21 through the air off gas outlet 127 from the air off gas chamber 127.

  In the fuel cell system 1 including the humidifier A21 having the above configuration, the body 103 in which the through hole 104 is formed is driven to change the relative position with the hollow fiber bundle 102. When the body 103 is displaced, a portion of the hollow fiber bundle 102 corresponding to the through hole 104 moves. As a result, the portion of the hollow fiber bundle 102 that is directly exposed to the air supplied from the through hole 104 is not fixed, so that only a specific portion of the hollow fiber bundle 102 does not deteriorate intensively.

  Therefore, according to the fuel cell system 1 of the present embodiment, partial deterioration of the hollow fiber bundle 102 can be suppressed, and as a result, the durability of the entire humidifier A21 can be improved. Further, since the power supply source for driving the body 103 is the fuel cell 20, a mechanism for suppressing partial deterioration of the hollow fiber bundle 102 can be completed in the fuel cell system 1.

  Further, since the hollow fiber bundle 102 and the body 103 are provided coaxially and are configured to rotate relative to each other about the axis thereof, the hollow fiber bundle 102 and the body 103 are attached to the shaft. The humidifier A21 can be prevented from increasing in size as compared with the case where it is configured to move relatively along, and is particularly advantageous in mounting on a vehicle.

  By the way, in the fuel cell system 1 of this embodiment, the hollow fiber bundle 102 is fixed to the casing 120 and the body 103 is rotatably supported with respect to the hollow fiber bundle 102, but the body 103 is fixed to the casing 120. The hollow fiber bundle 102 may be supported so as to be rotatable with respect to the body 103.

  In the present embodiment, a mechanism for rotating the body 103 is provided in the casing 120 and the body 103 is forcibly rotated by operating the mechanism. For example, the fuel cell system 1 is mounted on a vehicle. In such a case, the body 103 is configured to freely rotate around the hollow fiber bundle 102 without receiving a large resistance from surrounding members due to vibrations or the like acting on the humidifier A21 during traveling or the like. Also good.

  Furthermore, in this embodiment, dry air flows into the small holes (inner circumferences of the hollow fibers) of a large number of hollow fibers 101, and wet air off-gas flows into the gaps between the dense hollow fibers 101 (outer circumferences of the hollow fibers). Contrary to this, it is configured such that dry air flows into the gaps between the dense hollow fibers 101 and wet air off-gas flows into the small holes of many hollow fibers 101. Also good. Further, the humidified gas may be hydrogen gas (fuel gas) supplied to the fuel cell 20.

  Further, in this embodiment, the row of through holes 104 is formed in the circumferential direction of the body 103, but the plurality of through holes 104 may be arranged so as to draw a spiral, or draw a wavy line. It may be arranged. Alternatively, the body 103 may be irregularly disposed on the peripheral wall.

1 is a system configuration diagram schematically showing a fuel cell system according to an embodiment of the present invention. It is sectional drawing which shows the structure of a humidifier. It is sectional drawing which follows the II-II line of the humidifier shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 100 ... Humidification module, 101 ... Hollow fiber, 102 ... Hollow fiber bundle, 103 ... Body, 104 ... Through-hole (introduction hole), 120 ... Casing, 140 ... Drive part, A21 ... Humidifier

Claims (4)

A fuel cell system comprising: a fuel cell that generates electricity by an electrochemical reaction between an oxidizing gas and a fuel gas; and a humidifier that humidifies at least one of the oxidizing gas and the fuel gas supplied to the fuel cell,
The humidifier includes a bundle of hollow fibers capable of moisture exchange between a humidified gas flowing through one of the inner and outer circumferences and a humidified gas flowing through the other, and covers the outer circumference of the bundle of hollow fibers. And a body through which an introduction hole for introducing the humidified gas or the humidified gas is formed, and a relative position between the portion corresponding to the introduction hole in the bundle of hollow fibers and the introduction hole is variable. A fuel cell system.   2. The fuel cell system according to claim 1, wherein at least one of the bundle of hollow fibers and the introduction hole is driven by electric power of a fuel cell that generates electric power using a humidified gas humidified by the humidifier. The bundle of hollow fibers and the body formed with the introduction hole are provided coaxially,
3. The fuel cell system according to claim 1, wherein at least one of the bundle of hollow fibers and the introduction hole rotate relative to the other about the axis. 4. A bundle of hollow fibers capable of exchanging moisture between the humidified gas flowing through one of the inner and outer circumferences and the humidified gas flowing through the other, and the outer circumference of the bundle of hollow fibers covering the outer circumference of the humidified gas Or a humidifier having a body through which an introduction hole for introducing the humidifying gas is formed,
A humidifier in which a relative position between a portion corresponding to the introduction hole in the bundle of hollow fibers and the introduction hole is variable.

Images