JP2001332283A - Evaporator for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaporator for the fuel cell, capable of minimizing the response time when controlling the operating conditions by changing the ratio of methanol to water. SOLUTION: An upper header 12A, equipped with 2 stairs of the supply pathways 10, 11 supplying methanol 30 and water 31 respectively, is provided just on all the top surface of the heat exchanger 9. On the lower surface of the supply pathways 10, 11, plural numbers of the supply holes 13a, 13b are provided to pass methanol 30, water 31 or mixture of methanol 30 and water 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell evaporator, and more particularly to a structure for supplying a raw fuel liquid in a fuel cell evaporator.

[0002]

2. Description of the Related Art As a configuration of a conventional vaporizing section for producing a raw fuel vapor to be used as a fuel for a fuel cell body by vaporizing a liquid raw fuel, for example, the configuration shown in FIG. Research and development of polymer fuel cells "
National Institute of Advanced Industrial Science and Technology (March 1998)).

[0003] The vaporizing section basically includes a liquid raw fuel heating section 4.
1, an evaporating section 42 and a heat recovery section 43. The evaporating section 42 includes a liquid fuel dropping plate 42a and an evaporating plate 42b.
Is a structure in which a dispersion hole into which liquid raw fuel is dropped is provided in the plane, and the dropped raw fuel droplet has an evaporating plate 42 b
It evaporates above. The evaporating plate 42b has uneven heat transfer fins in a plane, and droplets are dropped between the heat transfer fins to evaporate on the evaporation surface. At this time, the liquid raw fuel composed of methanol and water is configured to be mixed on the upstream side of the vaporizing section and then supplied to the evaporating section 42.

[0004]

However, in the prior art, since the liquid raw fuel, methanol and water, are mixed and supplied before being supplied to the evaporating section, the mixing ratio of methanol and water is reduced. When the operating conditions are controlled in a different manner, there is a problem that the responsiveness is reduced by the time required to discharge the raw fuel remaining in the raw fuel supply pipe to the evaporating section.

The present invention has been made in view of the above, and has as its object to reduce the response delay time as much as possible when controlling the operating conditions by changing the mixing ratio of methanol and water. It is an object of the present invention to provide a fuel cell evaporator capable of suppressing a decrease in the evaporation performance of a fuel cell.

[0006]

According to the first aspect of the present invention,
In order to solve the above-mentioned problems, in a fuel cell evaporator that vaporizes a liquid raw fuel composed of methanol and water to produce a raw fuel vapor serving as a fuel of a fuel cell body, a supply passage for supplying the methanol and water is provided. A two-tiered upper header is installed over the entire surface immediately above the heat exchange part, and a plurality of supply holes for passing the methanol, water, or a mixed solution of methanol and water are formed in the lower surface of each supply passage. The gist is to become

According to a second aspect of the present invention, in order to solve the above problems, the lower surfaces of the upper supply passage and the lower supply passage, which are the supply passages stacked in two stages, are both flat plates. .

According to a third aspect of the present invention, in order to solve the above-mentioned problem, the gist of the invention is that a supply hole of the lower supply passage is formed at substantially the same position as a supply hole of the upper supply passage.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, a gist of the invention is that a supply hole of the lower supply passage is formed at a position separated from a supply hole of the upper supply passage.

According to a fifth aspect of the present invention, in order to solve the above problems, the lower surface of each of the supply passages is a corrugated plate in the upper supply passage, a flat plate in the lower supply passage, and a corrugated plate in the upper supply passage. The gist of the invention is that the bottom is joined to the flat plate of the lower supply passage, and the supply hole of the upper supply passage is opened at the joint through the flat plate portion of the lower supply passage.

[0011]

According to the first aspect of the present invention, an upper header in which supply passages for supplying methanol and water are stacked in two stages is installed over the entire surface immediately above the heat exchange section, and the lower surface of each supply passage is provided. Has a plurality of supply holes through which the methanol, water, or a mixture of methanol and water is passed, so that methanol and water are separately supplied to the respective supply passages in the upper header portion and mixed in the lower supply passage. Since it is supplied to the heat exchange section, the response delay time can be reduced as much as possible when controlling the operating conditions by changing the mixing ratio of methanol and water.

According to the second aspect of the present invention, an upper header in which supply passages for supplying methanol and water are stacked in two stages is installed over the entire surface immediately above the heat exchange section. In the configuration in which a plurality of supply holes through which methanol, water, or a mixed solution of methanol and water is passed are formed, the lower surfaces of the upper supply passage and the lower supply passage, which are the supply passages stacked in two stages, are both formed. Because the plate is flat, the thickness of each supply passage can be made as small as possible, and the volume of each supply passage can be made smaller than the supply amount of methanol and water, so that the methanol or water supplied to the upper supply passage is reduced. After being mixed in the lower supply passage, it is uniformly fed to the heat exchange section under pressure, so that the response delay time can be further reduced when operating conditions are controlled by changing the mixing ratio of methanol and water. It becomes possible.

According to the third aspect of the present invention, an upper header in which supply passages for supplying methanol and water are stacked in two stages is provided over the entire surface immediately above the heat exchange section, and a lower surface of each of the supply passages is provided. In the configuration in which a plurality of supply holes through which methanol, water, or a mixed solution of methanol and water is passed are formed, the supply hole of the lower supply passage is formed at substantially the same position as the supply hole of the upper supply passage. Methanol or water is easily supplied from the supply passage directly to the heat exchange section via the supply hole of the lower supply passage, and when controlling the operation conditions by changing the mixture ratio of methanol and water, the original mixture having a predetermined mixture ratio is used. The response delay time until the fuel can be supplied can be further reduced.

According to the present invention, an upper header in which supply passages for supplying methanol and water are stacked in two stages is provided over the entire surface immediately above the heat exchange section, and the lower surface of each supply passage is provided on the lower surface of each supply passage. In the configuration in which a plurality of supply holes for passing the methanol, water, or a mixed solution of methanol and water are formed, a supply hole for the lower supply passage is formed at a position separated from the supply hole for the upper supply passage. Since the mixture of methanol and water is supplied to the heat exchange unit after being promoted in the lower supply passage, a decrease in the evaporation performance of the heat exchange unit can be suppressed.

According to the fifth aspect of the present invention, an upper header in which supply passages for supplying methanol and water are stacked in two stages is installed over the entire surface immediately above the heat exchange section, and the lower surface of each supply passage is provided on the lower surface of each supply passage. In the configuration in which a plurality of supply holes for passing the methanol, water, or a mixed solution of methanol and water are formed, the lower surface of each supply passage is a corrugated plate in the upper supply passage and a flat plate in the lower supply passage, Since the bottom of the corrugated plate in the upper supply passage is joined to the flat plate of the lower supply passage, and at this joint, the supply hole of the upper supply passage is opened through the flat plate portion of the lower supply passage, so that methanol and Water can be supplied directly to the heat exchange unit, and even when the mixing ratio of methanol and water is changed, the response delay time until the supply of raw fuel with a predetermined mixing ratio is reduced. It can be shortened in La.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a diagram showing a configuration of a fuel cell system including a fuel cell evaporator according to a first embodiment of the present invention. First, the configuration of the fuel cell system will be described.

In FIG. 1, a compressor 1 supplies air (oxygen) taken in from the outside to a fuel cell stack 2 and a reforming system 5. The fuel cell stack (fuel cell main body) 2 is provided with an anode 3 and a cathode 4, and generates power using hydrogen in the reformed gas and oxygen in the air.

The reforming system 5 includes an evaporator 6, a combustion catalyst 21 for generating a high-temperature exhaust gas 26 serving as a heat source of the evaporator 6, a mixer 22 installed sequentially upstream of the evaporator 6, a vaporization heater 23, and a methanol supply. Section 24 and vaporization heater 23
And a battery 25 for driving the evaporator 6.
And a CO removing unit 29 for removing CO in the reformed gas from the reforming unit 28 from which the raw fuel vapor 27 and the air are supplied to perform the methanol reforming.

In the methanol tank, methanol 30 is stored, and in the water tank, water 31 is stored. The pumps 32a and 32b suck the methanol 30 and the water 31 and supply them to the flow control valves 33a and 33b. In the flow control valves 33a and 33b, the raw fuel vapor 27 generated by the evaporator 6 is converted by the reforming section 28. The supply amounts of methanol 30 and water 31 are adjusted so as to have a required composition.

FIG. 2 shows the structure of the evaporator 6 described above.

In FIG. 2, a liquid raw fuel composed of methanol 30 and water 31 flows through the fins 7 on the refrigerant side, and a high-temperature exhaust gas 26 flows through the fins 8 on the heat medium side. A heat exchanging part 9 is constituted by an assembling part of the heat medium side fins 8 and 7.

An upper supply passage 10 for supplying methanol 30 to the heat exchange section 9 and a lower supply passage 11 for supplying water
The upper header 12 </ b> A in which the upper and lower parts are overlapped in two stages is installed over the entire surface immediately above the heat exchange unit 9. A plurality of supply holes 13a through which methanol 30 passes are uniformly opened on the lower surface 14a of the upper supply passage 10, and methanol 30 and water 3 are provided on the lower surface 14b of the lower supply passage 11.
A plurality of supply holes 1 through which the mixed liquid (liquid raw fuel) passes
3b is uniformly opened over the entire lower surface. In the lower part of the evaporator 6, a lower header 15 and a raw fuel vapor outlet 16 are provided.
Is provided.

Next, the operation of the evaporator 6 will be described together with the operation of the fuel cell system.

When the reforming system 5 is started, the supply of the air 35 to the mixer 22 via the air supply path 34 by the compressor 1 is started, and then the methanol 30 is supplied from the methanol supply section 24. The methanol 30 is vaporized by the vaporization heater 23, mixed with the air 35 by the mixer 22, and burned by the combustion catalyst 21.

After the start-up, the anode gas 36 and the cathode gas 37 discharged from the fuel cell stack 2 are introduced into the mixer 22 and mixed, and the combustion catalyst 2
Combustion at 1. The heat of the exhaust gas 26 generated during each of these combustions is used as a heat source of the evaporator 6.

In the evaporator 6, methanol 30 and water 31
Is supplied to the upper supply passage 10 and the lower supply passage 11 through the flow control valves 33a and 33b, respectively. The methanol 30 is temporarily supplied from the upper supply passage 10 to the lower supply passage 11 through the supply hole 13a,
After being mixed with the water in 1, the water passes through the supply hole 13b and is supplied to the heat exchange section 9 as a liquid raw fuel.

Here, heat exchange is performed with the exhaust gas 26,
The vaporized raw fuel vapor 27 passes through a reforming section 28 and a CO removing section 29 to become a reformed gas 38, and the fuel cell stack 2
To the anode 3. Air 35 is sent from the compressor 1 to the cathode 4 of the fuel cell stack 2, where power is generated using hydrogen in the reformed gas 38 and oxygen in the air 35.

The evaporator 6 operates as described above, and the methanol 30 and water 31 are supplied to the upper supply passage 10 and the lower supply passage 1.
, The lower supply passage 1 immediately before the heat exchange section 9
Since it is mixed at 1 and supplied to the heat exchange section 9, the response delay time can be reduced as much as possible when controlling the operating conditions by changing the mixing ratio of methanol 30 and water 31. Here, as shown in FIG. 2, the lower surfaces 14a, 14b of the upper supply passage 10 and the lower supply passage 11 in the upper header 12A are both flat plates, and a plurality of supply holes 13a, 13b are formed. Each of the lower surfaces 14a and 14b is uniformly opened over the entire lower surface 14a and 14b.

For this reason, each of the upper and lower supply passages 1
The thickness of each of the supply passages 10 and 11
Can be made sufficiently smaller than the supply amounts of methanol 30 and water 31. Thereby, the flow control valve 33
a, 33b via the upper supply passage 10 and the lower supply passage 1
The methanol 30 and the water 31 supplied separately to each other are mixed in the lower supply passage 11 and then uniformly supplied to the heat exchange unit 9 under pressure.

As a result, the response delay time of the raw fuel supply to the heat exchange section 9 at the time of starting the reforming system 5 or the response delay time when controlling the operating conditions by changing the mixing ratio of methanol 30 and water 31 is further increased. Can be shortened.

As shown in FIG. 3, the position of the supply hole 13a opened in the lower surface 14a of the upper supply passage 10 and the position of the supply hole 13b opened in the lower surface 14b of the lower supply passage 11 are as follows. They are in the same position.

As a result, the methanol 30 from the upper supply passage 10 is easily supplied directly to the heat exchange section 9 via the supply holes 13b of the lower supply passage 11, so that when the mixing ratio of the raw fuel is changed, a predetermined amount is required. The response delay time until the supply of the raw fuel having the mixing ratio of can be further reduced.

(Second Embodiment) FIG. 4 is a diagram showing a configuration of an upper header portion of a fuel cell evaporator according to a second embodiment of the present invention. The second embodiment and a third embodiment described later have the same basic configuration as the fuel cell evaporator corresponding to the first embodiment shown in FIG. The same reference numerals are given to the components of
The description is omitted.

In the second embodiment, as shown in FIG. 4, in the configuration of the upper header 12B, the upper supply passage 1
The supply hole 13b of the lower supply passage 11 is opened at a position separated from the 0 supply hole 13a.

Thus, the methanol 30 supplied from the upper supply passage 10 is not directly supplied to the heat exchange unit 9 but is temporarily retained in the lower supply passage 11 to promote the mixing with the water 31. For this reason, the raw fuel mixed substantially uniformly is supplied to the heat exchanging unit 9, and it is possible to suppress a decrease in the evaporation performance of the heat exchanging unit 9.

(Third Embodiment) FIG. 5 is a view showing a configuration of a fuel cell evaporator according to a third embodiment of the present invention.

In the third embodiment, as shown in FIG. 5, the lower surface of the upper supply passage 10 in the upper header 12C is a corrugated plate 17a, and the bottom 17b of the corrugated plate 17a is in the lower supply passage 11. Lower surface 1 made of a flat plate
4b.

At this joint, the supply hole 13a of the upper supply passage 10 is opened through the lower surface 14b of the lower supply passage 11. The upper stage supply passage 10 is provided with a predetermined interval between the lower corrugated plate 17a and the planar upper plate 18 so that the corrugations 17c can communicate with each other.

As shown in FIG. 6, one end of each wave portion 17c in the upper supply passage 10 is closed by a partition plate 19. The lower supply passage 11 is constituted by a plurality of prismatic hollow portions formed between the back surface of the corrugated plate 17 a and the lower surface 14 b made of a flat plate in the upper supply passage 10. The columnar hollow part is the partition plate 2.
0 and the lower surface 14b made of a flat plate communicate with each other through a space.

Since the third embodiment is configured as described above, methanol 30 or water 31 can be supplied to the heat exchange section 9 directly from the upper supply passage 10 or the lower supply passage 11.

Thus, even when the supply passages for the methanol 30 and the water 31 are vertically stacked, they can be individually supplied to the heat exchange section 9 by controlling the flow rate, and the mixing ratio of the raw fuel can be reduced. Even when changing, control can be performed while suppressing response delay.

In each of the embodiments described above, the upper supply passage 10 is a methanol passage and the lower supply passage 11 is a water supply passage.
The lower supply passage 11 also functions as a methanol supply passage,
The effect is the same as above.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a fuel cell system including a fuel cell evaporator according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a fuel cell evaporator according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of an upper header portion according to the first embodiment.

FIG. 4 is a diagram showing a configuration of an upper header portion of a fuel cell evaporator according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a fuel cell evaporator according to a third embodiment of the present invention.

FIG. 6 is an exploded perspective view showing a configuration of an upper header portion according to the third embodiment.

FIG. 7 is a diagram showing a basic configuration of a vaporization unit in a conventional fuel cell system.

[Explanation of symbols]

 Reference Signs List 2 fuel cell stack (fuel cell main body) 6 evaporator 9 heat exchange unit 10 upper supply passage 11 lower supply passage 12A, 12B, 12C upper header 13a, 13b supply hole 14a, 14b flat lower surface 17a corrugated plate 17b corrugated plate Bottom 30 methanol 31 water

Claims (5)

[Claims] 1. A fuel cell evaporator for producing a raw fuel vapor serving as fuel for a fuel cell main body by vaporizing a liquid raw fuel comprising methanol and water, wherein a supply passage for supplying methanol and water is provided in two stages. Is installed over the entire surface immediately above the heat exchange section, and the methanol, water,
Alternatively, a fuel cell evaporator is provided with a plurality of supply holes through which a mixture of methanol and water passes. 2. The fuel cell evaporator according to claim 1, wherein the lower surfaces of the upper supply passage and the lower supply passage, which are the supply passages stacked in two stages, are both flat plates. 3. The fuel cell evaporator according to claim 1, wherein a supply hole of the lower supply passage is formed at substantially the same position as a supply hole of the upper supply passage. 4. The fuel cell evaporator according to claim 1, wherein a supply hole of the lower supply passage is formed at a position separated from a supply hole of the upper supply passage. 5. A lower surface of each of the supply passages is a corrugated plate in the upper supply passage, and a flat plate in the lower supply passage,
The bottom of the corrugated plate in the upper supply passage is joined to the flat plate of the lower supply passage, and the supply hole of the upper supply passage is opened at the joint by passing through the flat plate of the lower supply passage. The fuel cell evaporator according to claim 1, wherein