JP2004224621A - Reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reformer having an evaporator made compact in the combustion gas flow direction and to provide the reformer in which the liquid jump from an evaporation part to a super heat part is prevented. <P>SOLUTION: (1) The reformer 1 has the evaporator structured by connecting a 1st heat exchanger part 14 to a 2nd heat exchanger part 15 through a U-turn part 12. (2) The 1st heat exchange part 14 is composed of the evaporation part and the 2nd heat exchange part 15 is composed of the super heat part. (3) The reformer has a guide part 17 provided in a communication passage 16. (4) The reformer has the communication passage 16 composed of a bellows pipe 18. (5) The reformer has heat transfer fins 20 made noncontinuous. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reformer provided with an evaporator for generating a reforming material gas for a fuel cell.
[0002]
[Prior art]
The natural gas evaporator has a structure in which high-temperature raw material gas for reforming is generated by heat exchange of reforming water, air, and natural gas with high-temperature combustion gas in the evaporator.
Japanese Patent Application Laid-Open No. 2002-39023 discloses an evaporator, in which a laminated heat exchanger having continuous fins in which a raw material gas flow path is arranged in a meandering manner in a straight combustion gas flow path. In this case, a reforming source gas is generated by heat exchange in the above.
[0003]
[Patent Document 1]
JP-A-2002-39023
[Problems to be solved by the invention]
However, the above prior art has the following problems.
Since the combustion gas flow path is straight, the evaporator becomes longer in the direction of the combustion gas flow path, and it is difficult to make the evaporator compact, which makes mounting on a vehicle difficult.
Since the fins are formed continuously, the reforming water splashes from the evaporating section to the superheat section along the fins (liquid reforming water that has not completely evaporated jumps off the superheat section), and Thermal stress occurs due to the temperature difference between the droplet and the combustion gas in the fins of the portion, and the durability of the superheat portion is reduced.
An object of the present invention is to provide a reformer that can make the evaporator compact in the combustion gas flow direction.
It is another object of the present invention to provide a reformer that can prevent the reforming water from splashing from the evaporating section to the superheat section along the fins.
[0005]
[Means for Solving the Problems]
The present invention that achieves the above object is as follows.
(1) a combustion gas flow path having a U-turn portion in the middle and through which combustion gas flows,
A fluid flow path in which a reforming material fluid that is vaporized by heat exchange with the combustion gas flows therein,
A first heat exchange unit that is provided in a combustion gas flow path downstream of the U-turn unit when viewed in the flow direction of the combustion gas and forms a part of the fluid flow path and exchanges heat with the combustion gas;
A second heat exchange section that is provided in a combustion gas flow path on the upstream side of the U-turn section when viewed in the flow direction of the combustion gas and forms a part of the fluid flow path and exchanges heat with combustion gas;
A communication passage that communicates the first heat exchange unit and the second heat exchange unit separately from the U-turn unit, forms a part of the fluid flow path, and flows the fluid vapor therein;
A reformer provided with an evaporator having:
(2) The reformer according to (1), wherein the first heat exchange section comprises an evaporator section, and the second heat exchange section comprises a superheat section.
(3) The reformer according to (1) or (2), wherein a guide for suppressing the movement of the evaporating fluid in a droplet state is provided in the communication path.
(4) The reformer according to (1), (2) or (3), wherein the communication passage is formed of a bellows pipe.
(5) The reformer according to (1), wherein the heat transfer fins of the portion of the first heat exchange section that is in contact with the fluid are discontinuous when viewed in the flow direction of the fluid.
[0006]
In the reformer of the above (1), since the first heat exchange section and the second heat exchange section are connected via the U-turn section when viewed in the combustion gas flow direction, the evaporator can be made compact in the combustion gas flow direction. it can.
In the reformer of the above (2), since the evaporator and the superheater are connected via the U-turn part when viewed in the combustion gas flow direction, the evaporator can be made compact in the combustion gas flow direction.
In the reformer of the above (3), since a guide is provided in a communication path which constitutes a part of the fluid flow path and communicates the evaporating section and the superheat section, it is included in the fluid in the communication path. The movement of liquid droplets that may occur is suppressed, and as a result, liquid splash from the evaporating section to the superheat section can be prevented.
In the reformer of the above (4), since the communication path which constitutes a part of the fluid flow path and connects the evaporating section and the superheat section is constituted by the bellows pipe, it is included in the fluid in the communication path. The movement of liquid droplets that may occur is suppressed, and as a result, liquid splash from the evaporating section to the superheat section can be prevented. In addition, the thermal stress of the bellows pipe can be reduced.
In the reformer of the above (5), since the heat transfer fin that is in contact with the fluid in the evaporating section is discontinuous in the fluid flow direction, the liquid that may be contained in the fluid after passing through the heat transfer fin. The movement of the droplet can be suppressed, and the liquid can be prevented from splashing from the evaporating section to the superheat section.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the reformer of the present invention will be described with reference to FIGS. However, FIG. 3 is a comparative example (not included in the present invention).
As shown in FIG. 1, the reformer 1 of the present invention is a reformer provided with an evaporator 10. The reformer 1 includes a reforming section, a shift reaction section, and a CO reduction section on the downstream side of the evaporator 10 as viewed in the flow direction of the fluid 3.
[0008]
The evaporator 10
A combustion gas passage 11 having a U-turn portion 12 in the middle and through which the combustion gas 2 flows;
A fluid passage 13 through which the reforming material fluid 3 which is vaporized by heat exchange with the combustion gas 2 and further turned into superheated steam flows therein;
A first heat exchange section 14 provided in the combustion gas flow path 11 on the downstream side of the U-turn section 12 as viewed in the flow direction of the combustion gas 2 and constituting a part of a fluid flow path 13 and performing heat exchange with the combustion gas 2; ,
A second heat exchange section 15 provided in the combustion gas flow path 11 on the upstream side of the U-turn section 12 as viewed in the flow direction of the combustion gas 2 and constituting a part of the fluid flow path 13 to exchange heat with the combustion gas 2; ,
A communication path 16 that communicates the evaporating section 14 and the superheat section 15 with a separate flow path from the U-turn section 12 to form a part of a fluid flow path 13 and to flow the fluid vapor 3 therein;
Having.
The first heat exchange unit 14 includes an evaporator 14 (same as the first heat exchange unit 14) that evaporates the fluid 3 by heat exchange with the combustion gas 2.
The second heat exchange section 15 is a superheat section 15 (second section) that superheats the fluid vapor (with the same reference numeral 3 as the fluid 3) to the superheated steam (with the same reference numeral 3 as the fluid 3) by heat exchange with the combustion gas 2. 2 is given the same symbol as the heat exchange unit 15).
The combustion gas 2 does not flow between the flow path wall of the communication passage 16 and the casing outside the flow path wall. The combustion gas 2 flows from the superheat section 15 to the evaporation section 14 through the U-turn section 12.
The fluid flow path 13 has manifolds 13A and 13B at the entrance and exit of the evaporating section 14 and manifolds 13C and 13D at the entrance and exit of the superheat section 15 when viewed in the flow direction of the fluid 3.
[0009]
The evaporator 14 and the superheater 15 are parallel to each other, and the communication path 16 is orthogonal to the evaporator 14 and the superheater 15. The flow direction of the high-temperature gas 2 in the evaporating section 14 and the flow direction of the high-temperature gas 2 in the superheat section 15 are opposite to each other. The flow direction of the fluid 3 in the evaporator 14 and the flow direction of the fluid 3 in the superheater 15 are opposite to each other.
[0010]
On the upstream side of the evaporator 14 in the flow direction of the fluid 3, the room temperature reformed water 4 is introduced into the evaporator 14, and at least a part of the reformed water 4 is evaporated in the evaporator 14. On the downstream side of the evaporator 14 in the flow direction of the fluid 3, a reforming air and a raw material gas 5 for mixing natural gas such as methane at room temperature are introduced. The reformed water 4 or its vapor, or a mixed gas of the reformed water 4 or its vapor and the reforming raw material gas 5 constitutes a liquid 3 or a fluid 3 composed of a liquid and a gas.
The fluid 3 composed of the reforming water 4 or a mixed gas of the vapor of the reforming water 4 and the raw material gas 5 flows through the communication passage 16 to the superheat section 15, where it is converted into superheated steam (superheated steam). It becomes a reformed gas (reformed raw material gas) and flows to a reforming section (not shown) in the next step.
[0011]
The temperature of the combustion gas 2 is about 650 ° C. at the entrance of the combustion gas 2 to the superheat section 15 (the exit from the superheat section 15 when viewed from the fluid 3), and the exit of the combustion gas 2 from the superheat section 15 The temperature is about 500 ° C. (at the entrance to the superheat section 15 as viewed from the fluid 3). The combustion gas at about 500 ° C. maintains its temperature and passes through the U-turn section 12 to reach the inlet of the combustion gas 2 to the evaporator section 14 (the outlet from the evaporator section 14 as viewed from the fluid 3). The temperature of the combustion gas 2 is about 500 ° C. at the inlet of the combustion gas 2 to the evaporator 14 (the outlet from the evaporator 14 when viewed from the fluid 3), and the outlet of the combustion gas 2 from the evaporator 14 (the fluid 3) From the entrance to the evaporating section 14).
[0012]
The temperature of the reforming water 4 is normal at the inlet of the fluid 3 to the fluid flow path 13, and is about 200 ° C. at the outlet from the evaporator 14. The temperature of the air-fuel mixture of the natural gas and the reforming air is room temperature at the inlet to the fluid flow path 13, and is about 200 ° C. after merging with the steam of the reforming water 4 at the outlet from the evaporator 14. Fluid 3 vapor (which may contain droplets) flows through communication passage 16 at about 200 ° C. and is at about 200 ° C. at the entrance of fluid 3 vapor to superheat section 15. The fluid 3 vapor is superheated in the superheat section 15, and the temperature of the fluid 3 superheated vapor is about 500 ° C. at the outlet from the superheat section 15.
[0013]
Both the evaporator 14 and the superheater 15 are formed of a stacked heat exchanger. As shown in FIG. 6, for example, the laminated heat exchanger is formed by laminating a corrugated plate (fin) 20 and a flat plate 21 in a plurality of layers, and a layer in which the fluid 3 flows and the combustion gas 2 are formed. The flowing layers are alternately arranged in the laminating direction.
[0014]
The fluid 3 may not be completely evaporated in the evaporator 14, especially during high-load operation (when a large amount of reforming water is introduced), in which case a part of the fluid 3 is liquid at the outlet of the evaporator 14. May be drops. Also, when a mixture of natural gas and air at normal temperature is introduced and mixed with the fluid 3 that has passed through the evaporator 13, part of the evaporative reformed gas may become droplets at the outlet of the evaporator 14. Again, some of the fluid 3 may be droplets at the outlet of the evaporator 14.
When the droplets flow (liquid splash) from the evaporating section 14 into the superheat section 15, one surface of the flat plate of the heat exchanger constituting the superheat portion 15 comes into contact with the high-temperature combustion gas 2 and the other surface of the flat plate becomes liquid. Drops adhere and create a large temperature difference between the two surfaces, causing large thermal stresses and reducing the durability of the heat exchanger. In order to prevent this, in the present invention, at least one of the following two measures (suppression of droplets passing through the fin in the evaporator and suppression of movement in the liquid state in the communication path) is performed as described below. Be taken.
[0015]
FIG. 2 shows the fins 21 made of corrugated sheets in the layer of the heat exchanger constituting the evaporator 14 where the fluid 3 flows. As shown in FIG. 2, the fins 21 are discontinuous (intermittent) fins in the flow direction of the fluid 3 composed of the high-temperature reforming water. That is, a space (gap) 22 is provided between the fins 21 in the flow direction of the fluid 3 (the same as the direction in which the ridges of the fins extend). By providing the space 22, the droplet 3A traveling along the fin 21 is cut at one peak. The water droplet broken at one mountain end evaporates effectively while leaving the mountain and flying in the space 22, or effectively evaporates while the droplet becomes smaller and repeats.
FIG. 3 shows a conventional continuous fin 20 '. When the droplet 3A flows along the continuous fin, the evaporation of the droplet may be hindered, and the liquid may fly to the superheat portion. When the liquid splash occurs, the durability of the heat exchanger in the superheat section is reduced.
[0016]
The space 22 provided on the ridge of one fin 21 and the space 22 provided on the ridge of the adjacent fin 21 are orthogonal to the flow direction of the fluid 3 (the direction in which the ridge of the fin extends). It is desirable that the directions do not coincide, i.e., are offset from each other. By doing so, the distance from one fin peak to the fin peak diagonally forward is increased, and the evaporation of liquid between the fin peaks is accelerated accordingly.
[0017]
FIG. 4 shows a countermeasure for liquid splash from the evaporating section 14 to the superheat section 15 in the communication path 16.
As shown in FIG. 4, a guide 17 for suppressing the movement of the evaporating fluid in a droplet state is provided in the communication path 16. Since the specific gravity of the liquid droplet is larger than that of the vapor, the liquid droplet passes through a lower portion in the cross section of the communication path 16, but the guide 17 is provided at a lower portion in the cross section of the communication path 16. The position of the guide 17 in the communication passage 16 becomes lower as it goes downstream in the flow direction of the fluid 3, and is an inclined surface. The guide 17 has an arc shape in a direction orthogonal to the direction in which the communication path 16 extends, and extends at a fixed interval between the guide 17 and the inner surface of the wall of the communication path 16. When the liquid droplets flow in the communication path 16, the liquid droplets fall on the lower wall surface of the communication path 16 on the guide 17.
[0018]
As shown in FIG. 4, the wall of the communication passage 16 is constituted by a bellows pipe 18. The bellows pipe 18 has a plurality of bellows recesses 19, and the guide 17 is located above the recesses 19. The droplets that fall on the guides 17 and fall under their own weight flow downstream while entering and leaving the dents 19, the flow path lengths become longer, the time and distance of contact with the hot gas become longer, and they are effectively evaporated to complete vapor. And flows to the superheat section 15.
[0019]
Next, the operation will be described.
In the evaporator 10, since the evaporator 14 and the superheater 15 are connected via the U-turn 12 when viewed in the flow direction of the combustion gas 2, the length of the heat exchange part of the evaporator 10 in the flow direction of the combustion gas 2 Is reduced to about 1/2, and the evaporator 10 is made compact. This facilitates mounting on a vehicle or the like.
[0020]
Further, since the guide 17 is provided in the communication path 16, the inflow of the liquid droplets, which may be included in the fluid, into the superheat section 15 in the communication path 16 is suppressed. As a result, liquid splash from the evaporator 14 to the superheater 15 is prevented.
Further, since the wall of the communication passage 16 is formed of the bellows pipe 18, the movement of the droplets that may be included in the fluid in the communication passage 16 is suppressed. As a result, liquid splash from the evaporator 14 to the superheater 15 can be prevented. Moreover, because of the bellows pipe 18, even if there is a difference in thermal expansion between the bellows pipe 18 and both ends of the bellows pipe 18, the thermal stress of the bellows pipe 18 can be reduced by the expansion and contraction of the bellows pipe 18.
[0021]
Further, the heat transfer fins 21 of the heat exchanger layer of the evaporating section 14 that is in contact with the fluid 3 (not the heat transfer fins of the heat exchanger layer that is in contact with the combustion gas 2) are discontinuous in the flow direction of the fluid 3. Therefore, it is possible to suppress the movement of the liquid droplets that may be contained in the fluid 3 along the heat transfer fins 21 and prevent the liquid from jumping from the evaporating unit 14 to the superheat unit 15.
[0022]
【The invention's effect】
According to the reformer of the first aspect, the first heat exchange unit 14 and the second heat exchange unit 15 are connected via the U-turn unit 12 when viewed in the combustion gas 2 flow direction. In addition, the evaporator 10 can be made compact. This is advantageous in mounting on a vehicle.
According to the reformer of claim 2, since the evaporator 14 and the superheater 15 are connected via the U-turn part 12 when viewed in the combustion gas 2 flow direction, the evaporator 10 is connected in the combustion gas 2 flow direction. Can be made compact. This is advantageous in mounting on a vehicle.
According to the reformer of the third aspect, since the guide 17 is provided in the communication path 16, it is possible to prevent the liquid from jumping from the evaporator 14 to the superheater 15.
According to the reformer of the fourth aspect, since the communication path 16 is constituted by the bellows pipe 18, it is possible to prevent the liquid from flowing from the evaporator 14 to the superheater 15. In addition, the thermal stress of the bellows pipe 18 can be reduced.
According to the reformer of the fifth aspect, since the heat transfer fins 21 in contact with the fluid 3 in the evaporator 14 are discontinuous in the flow direction of the fluid 3, the heat transfer fins 21 are included in the fluid after passing through the heat transfer fins 21. It is possible to suppress the movement of liquid droplets that may be flowing, and to prevent the liquid from jumping from the evaporating section 14 to the superheat section 15.
[Brief description of the drawings]
FIG. 1 is a sectional view of an evaporator part of a reformer of the present invention.
FIG. 2 is a perspective view of a heat transfer fin of an evaporator portion of the reformer of FIG.
FIG. 3 is a perspective view of a heat transfer fin of an evaporator portion of a comparative example.
FIG. 4 is a sectional view of a communication passage portion of the reformer of FIG.
FIG. 5 is a cross-sectional view of a heat exchanger constituting an evaporator of the reformer of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reformer 2 Combustion gas 3 Fluid 3A Droplet 10 Evaporator 11 Combustion gas flow path 12 U-turn section 13 Fluid flow paths 13A, 13B, 13C, 13D Manifold 14 First heat exchange section (evaporation section)
15 Second heat exchange section (super heat section)
16 Communication passage 17 Guide 18 Bellows pipe 19 Depression 20 Corrugated plate (fin)
21 flat plate 22 space

Claims (5)

A combustion gas flow path having a U-turn portion in the middle and through which combustion gas flows,
A fluid flow path in which a reforming material fluid that is vaporized by heat exchange with the combustion gas flows therein,
A first heat exchange unit that is provided in a combustion gas flow path downstream of the U-turn unit when viewed in the flow direction of the combustion gas and forms a part of the fluid flow path and exchanges heat with the combustion gas;
A second heat exchange section that is provided in a combustion gas flow path on the upstream side of the U-turn section when viewed in the flow direction of the combustion gas and forms a part of the fluid flow path and exchanges heat with combustion gas;
A communication passage that communicates the first heat exchange unit and the second heat exchange unit separately from the U-turn unit, forms a part of the fluid flow path, and flows the fluid vapor therein;
A reformer provided with an evaporator having: The reformer according to claim 1, wherein the first heat exchange section comprises an evaporator section, and the second heat exchange section comprises a superheat section. 3. The reformer according to claim 1, wherein a guide is provided in the communication path to suppress movement of the evaporating fluid in a droplet state. 4. The reformer according to claim 1, wherein the communication path is formed of a bellows pipe. 2. The reformer according to claim 1, wherein the heat transfer fin of a portion of the first heat exchange section that is in contact with the fluid is discontinuous when viewed in a flow direction of the fluid.

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