JP2008121910A - Humidity exchange type humidifier and fuel cell power generation system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a humidity exchange type humidifier and a fuel cell power generation system using the same, capable of reducing variations of a pressure and a flow rate of a humidified gas, and reducing condensate water included in the gas discharged after exchanging humidity with a gas supplied from the external. <P>SOLUTION: This humidity exchange-type humidifier for allowing the first gas supplied from the external to exchange humidity with the second gas having a humidity higher than the first gas, through a moisture permeable film, comprises a condensate water draining mechanism connected with an outlet manifold portion disposed at an outlet of the second gas. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a humidity exchange type humidifier that exchanges moisture between a supply gas and an off gas, and a fuel cell power generation system that generates power using the humidified supply gas.

  In a conventional polymer electrolyte fuel cell system, when generating electricity, a large amount of water vapor is generated in the fuel cell, which is condensed in the air-side humidifier or air-side flow path, and the air-side pressure and air flow rate fluctuate. Because there is a problem that the battery characteristics deteriorate, the fuel cell is located at the top and the humidity exchange type is located below the fuel cell so that water droplets that are condensed can flow smoothly using gravity A humidifier is located and an air side water recovery device needs to be located under the humidity exchange type humidifier (for example, refer to patent documents 1).

JP 2000-156236 A

In such a polymer electrolyte fuel cell system, the fuel cell is located at the top, the humidity exchange type humidifier is located below the fuel cell, and the water recovery heat exchange is located below the humidity exchange type humidifier. Therefore, there is a problem that the height of the fuel cell system is restricted by these fuel cells, the humidity exchange type humidifier, and the water recovery heat exchanger, and cannot be reduced in size or placed freely.
In addition, when the polymer electrolyte fuel cell system is stopped, air is supplied from below the humidity exchange type humidifier, so that the condensed water in the humidity exchange type air humidifier is pulled from the air supply port of the humidity exchange type air humidifier. Flows out to the air supply device, and this water causes a problem in the air supply device.

  An object of the present invention is to provide a humidity exchange type humidifier in which the fluctuation of the pressure and flow rate of the gas to be humidified is small and the condensed gas contained in the gas discharged by exchanging humidity with the gas supplied from the outside is small. Was to provide a fuel cell power generation system.

  The humidity exchange type humidifier according to the present invention is a humidity exchange type humidifier which exchanges humidity through a moisture permeable membrane for the first gas supplied from the outside through the second gas having a higher humidity than the first gas. The humidifier includes a condensed water drainage mechanism connected to an outlet manifold portion provided at the outlet of the second gas.

  The effect of the humidity exchange type humidifier according to the present invention is that the condensate drainage mechanism is connected to the outlet manifold portion, so that fluctuations in the pressure and flow rate of the gas to be humidified are small and the first gas supplied from the outside This means that the condensed water contained in the second gas discharged after exchanging the humidity is small.

Embodiment 1 FIG.
1 is an arrangement configuration diagram of a solid polymer fuel cell power generation system according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of the humidity exchange type humidifier 5 according to Embodiment 1 of the present invention. In FIG. 1, the positional relationship in the system housing 9 of the elements constituting the fuel cell power generation system is shown.
As shown in FIG. 1, a solid polymer fuel cell system includes a fuel cell 1 that generates power using hydrogen-containing fuel gas and air, a supply air 2 and a second gas as a first gas supplied from the outside. Humidity exchange type humidifier 5 that exchanges humidity with off-gas 3 as a gas to generate humidified air 4 and supplies it to fuel cell 1, and off-gas 6 that has undergone humidity exchange with supply air 2 to reduce humidity A water recovery heat exchanger 7 for recovering water, a humidity exchange type humidifier 5 and a water tank 8 in which water generated by the water recovery heat exchanger 7 is stored are provided.

The fuel cell 1 is disposed in the upper part of the system housing 9, and a fuel such as natural gas is steam reformed from a hydrogen generator (not shown), and a hydrogen-rich humidified fuel gas is supplied to the fuel electrode of the fuel cell 1. .
Further, as the oxidant, supply air 2 is supplied from an air supply device (not shown), and humidified air 4 humidified by the humidity exchange type humidifier 5 is supplied to the air electrode of the fuel cell 1.

The humidity exchange type humidifier 5 is disposed below the fuel cell 1 in the system housing 9. This is because the off gas 3 containing the condensed water from the fuel cell 1 flows smoothly and led to the humidity exchange type humidifier 5.
The water recovery heat exchanger 7 is disposed at a position where the humidity exchange type humidifier 5 overlaps the vertical direction.
The water tank 8 is disposed at a position lower than the humidity exchange type humidifier 5 and the water recovery heat exchanger 7, that is, at the lower part of the system housing 9.

Next, the humidity exchange type humidifier 5 will be described.
When the electrolyte membrane of the polymer electrolyte fuel cell 1 is dried, the ionic conductivity is reduced and the electrolyte function is lost. Therefore, it is necessary to keep the electrolyte membrane in a certain water-containing state. For this reason, a method is generally employed in which humidified air 4 is supplied to the fuel cell 1 to keep the electrolyte membrane moist. The humidity exchange type humidifier 5 is provided to generate the humidified air 4.

As shown in FIG. 2, the humidity exchange type humidifier 5 is disposed between a supply air passage 11 through which the supply air 2 flows, an offgas passage 12 through which the offgas 3 flows, and between the supply air passage 11 and the offgas passage 12. The moisture permeable membrane 13 connected to one end of the supply air channel 11 and supplied with the supply air 2, and the humidified air connected to the other end of the supply air channel 11 and discharged from the humidified air 4. An outlet manifold section 15, an offgas inlet manifold section 16 connected to one end of the offgas flow path 12 and supplied with the offgas 3, and an offgas outlet manifold section connected to the other end of the offgas flow path 12 and discharged with reduced offgas 6. 17, a drain line 19 connected to a drain hole 18 provided at the bottom of the off-gas outlet manifold 17 is provided.
The drain hole 18 and the drain line 19 are collectively referred to as a condensed water drain mechanism.

  The off-gas outlet manifold portion 17 is arranged so that the off-gas 6 flows upward, and the cross-sectional area is increased in order to reduce the flow rate of the off-gas 6 so that the off-gas 6 does not transport the condensed water 21 due to condensation. The outlet of the off-gas outlet manifold portion 17 is opened on the upper surface of the humidity exchange type humidifier 5. By using such an off-gas outlet manifold section 17, even in the off-gas 6 where moisture and heat are taken away by the humidity exchange type humidifier 5 and the humidity is lowered, the condensed water 21 due to condensation is generated in the off-gas outlet manifold section 17. However, the condensate 21 is not transferred to the water recovery heat exchanger 7 together with the offgas 6 but is accumulated at the bottom of the offgas outlet manifold 17 by making the flow direction of the offgas 6 upward and slowing the flow velocity. be able to.

An inlet of the off-gas inlet manifold section 16 is opened on the upper surface of the humidity exchange type humidifier 5 in order to receive the off-gas 3 flowing down from the fuel cell 1.
Further, the outlet of the humidified air outlet manifold section 15 and the inlet of the supply air inlet manifold section 14 are opened on the upper surface of the humidity exchange type humidifier 5.

The drain hole 18 is provided at the bottom of the off-gas outlet manifold 17 and guides the dripping condensed water 21 to the drain line 19.
The drainage line 19 communicates a drainage hole 18 provided at the bottom of the off-gas outlet manifold 17 and a downstream pipe 22 of the water recovery heat exchanger 7. The condensed water 21 due to condensation flows out from the drain hole 18 to the drain line 19 and flows to the downstream pipe 22.
The pressure loss of the drainage line 19 is sufficiently larger than the pressure loss of the offgas outlet manifold section 17 and the water recovery heat exchanger 7. For example, even if offgas circulates in the drainage line 19, the water recovery amount is not greatly affected. It is configured so that the amount of circulation is about.

  The humidity exchange type humidifier 5 humidifies and preheats the supply air 2 by bringing the supply air 2 flowing through the supply air flow path 11 and the off gas 3 flowing through the off gas flow path 12 into contact with each other through the moisture permeable membrane 13. 4 is generated. Thus, since the supply air 2 is humidified and preheated using the heat of the offgas 3 and the moisture contained therein, the humidity exchange type humidifier 5 does not need to supply humidification water from the outside. Sometimes, a large amount of heat of vaporization is not taken away, so that it can be used efficiently, and air humidification and preheating can be performed without requiring special control.

The off-gas 6 whose humidity and temperature have been lowered by the humidity exchange type humidifier 5 is guided to the water recovery heat exchanger 7, cooled by the water recovery heat exchanger 7, further dehumidified, and then introduced into the atmosphere via the water tank 8. Released.
Condensed water generated in the water recovery heat exchanger 7 and condensed water 21 from the drain line 19 of the humidity exchange type humidifier 5 flow down and are stored in the water tank 8 by gravity. The condensed water collected in the water tank 8 is used for steam reforming of the hydrogen generator.

Such a humidity exchange type humidifier 5 is provided with a condensate drainage mechanism connected to the off-gas outlet manifold section 17, so that the effect of small fluctuations in air-side pressure and air flow rate is obtained.
Moreover, the effect that there is little condensed water contained in the off gas discharged | emitted by exchanging humidity with the air supplied from the outside is acquired.

Further, when the humidity exchange type humidifier 5 is applied to the fuel cell power generation system, the position of the water recovery heat exchanger 7 is not restricted, and the degree of freedom of the water recovery heat exchanger 7 is increased. The fuel cell power generation system can be downsized.
Further, since the inlet of the supply air inlet manifold portion 14 is opened on the upper surface, the condensed water in the humidity exchange type humidifier 5 does not flow into the air supply device due to gravity when the fuel cell power generation system is stopped. The reliability of the supply device can be improved.

Embodiment 2. FIG.
FIG. 3 is a cross-sectional view of a humidity exchange type humidifier 5B according to Embodiment 2 of the present invention.
As shown in FIG. 3, the humidity exchange type humidifier 5B according to the second embodiment of the present invention is different from the humidity exchange type humidifier 5 according to the first embodiment in the off gas outlet manifold portion 17B. Therefore, the same parts are denoted by the same reference numerals and the description thereof is omitted.
The off gas outlet manifold portion 17B according to the second embodiment is provided with a condensed water pool space 30 at a position lower than the off gas flow path 12.
When the condensate pool space 30 is provided at the bottom of the off-gas outlet manifold portion 17B as described above, the air-side pressure and the air flow rate can be increased without changing the cross-sectional area of the air flow path even if the amount of the condensed water 21 to be generated varies. Fluctuations can be suppressed, and stable power generation characteristics can be obtained.

In Embodiments 1 and 2 described above, the moisture permeable membrane 13 has been described for the humidity exchange type humidifier 5 having a single layer. Good.
Moreover, although the case where the drain line 19 of the humidity exchange type humidifier 5 is connected to the downstream pipe 22 of the water recovery heat exchanger 7 has been described, it may be directly connected to the water tank 8.
Moreover, although the case where the drainage line 19 of the humidity exchange type humidifier 5 is drained downward has been described, the drainage line 19 may be drawn out from the lateral side surface of the humidity exchange type humidifier 5.
Moreover, although the humidity exchange type humidifier 5 which humidifies air was demonstrated, the humidity exchange type humidifier which humidifies fuel gas may be sufficient.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the polymer electrolyte fuel cell power generation system concerning Embodiment 1 of this invention. It is sectional drawing of the humidity exchange type humidifier concerning Embodiment 1 of this invention. It is sectional drawing of the humidity exchange type humidifier concerning Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel cell, 2 Supply air, 3, 6 Off gas, 4 Humidification air, 5 Humidity exchange type humidifier, 7 Water recovery heat exchanger, 8 Water tank, 9 System housing, 11 Supply air flow path, 12 Off gas flow path , 13 Moisture permeable membrane, 14 Supply air inlet manifold, 15 Humidified air outlet manifold, 16 Off gas inlet manifold, 17 Off gas outlet manifold, 18 Drain hole, 19 Drain line, 21 Condensed water, 22 Downstream piping, 30 Condensation Puddle space.

Claims (3)

In a humidity exchange type humidifier that humidifies by exchanging the humidity of the first gas supplied from outside through the moisture permeable membrane with the second gas having a higher humidity than the first gas,
A humidity exchange type humidifier comprising a condensed water drainage mechanism connected to an outlet manifold portion provided at an outlet of the second gas.   The humidity exchange type humidifier according to claim 1, wherein a condensate pool space is provided at a position lower than a lower portion of the outlet manifold of the second gas. In a fuel cell power generation system that introduces fuel and an oxidant into a fuel cell and generates power by an electrochemical reaction,
With respect to at least one gas of the fuel or the oxidant, a gas supplied from the outside is a gas after reaction that has flowed through the fuel cell using the humidity exchange type humidifier according to claim 1 or 2. A fuel cell power generation system characterized by humidifying by exchanging humidity.

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