JP2005040660A - Catalytic reactor, heat exchanger, and fuel reforming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger suitable for vaporizing a cooling medium by exchanging heat, a catalytic reaction apparatus and a system for reforming fuel. <P>SOLUTION: This catalytic reaction apparatus is provided with a catalyst layer 14 for causing an exothermic reaction, a porous body 18 and a cooling medium flow passage 13 capable of exchanging the heat with the catalyst layer 14. The porosity of the flow passage 13 is changed according to the distance from the catalyst layer 14. In the concrete, the porous body 18 is arranged on the side of the catalyst layer 14 and a space having the porosity smaller than that of the porous body 18 is arranged on the side parted from the catalyst layer 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Industrial application fields]
The present invention relates to a heat exchanger, a catalytic reaction apparatus, and a fuel reforming system. In particular, the present invention relates to a fuel reforming system including a structure of a portion for performing heat exchange of a heat exchanger or a heat exchange type catalytic reactor, and at least one of the heat exchanger or the catalytic reactor.
[0002]
[Prior art]
As a conventional heat exchanger, a heat exchanger having a plurality of inner pipes parallel to each other and an outer pipe 3 surrounding the entire inner pipe is known. Each inner pipe is filled with a porous sintered body, a cooling water inlet pipe is provided at the upper end of the outer pipe, and a cooling water outlet pipe is provided at the lower end. A spiral fin or a cylindrical porous body is provided by spirally winding and adhering to the outer peripheral surface of the inner pipe. Gas is passed through each inner pipe, and cooling water is passed through the outer pipe from the cooling water inlet pipe toward the cooling water outlet pipe. Thereby, a large contact surface with respect to the cooling water can be secured, and the heat exchange efficiency can be improved.
[0003]
[Patent Document 1]
JP 7-294163 A
[0004]
[Problems to be solved by the invention]
However, in the above conventional technique, the cooling water taken from the cooling water inlet pipe is supplied to the entire flow path cross section of the outer pipe. For this reason, it is considered that the volume of the cooling water increases in the cooling water flow path when the entire cross section of the flow path of the outer pipe is filled with liquid cooling water and the cooling water evaporates due to heat exchange. Not.
[0005]
In view of the above problems, an object of the present invention is to provide a heat exchanger, a catalytic reaction device, and a fuel reforming system having a configuration suitable for evaporating a refrigerant by heat exchange.
[0006]
[Means for solving problems]
The present invention includes a catalyst reaction device that includes a catalyst reaction layer that generates a reaction accompanied by heat generation and a porous body, and a refrigerant channel that is adjacent to the catalyst reaction layer so as to be able to exchange heat. The porosity of the refrigerant flow path is changed according to the distance from the catalyst reaction layer.
[0007]
Alternatively, the fuel reforming system includes a reforming reactor that generates reformed gas using at least water and fuel. Moreover, the carbon monoxide removal apparatus provided with the catalyst reaction layer which reduces the carbon monoxide in the said reformed gas, and the refrigerant | coolant flow path which performs heat exchange with the said catalyst reaction layer using a refrigerant | coolant is provided. Furthermore, a steam generation unit that generates steam or fuel vapor using heat generated in the catalytic reaction layer is provided. As the carbon monoxide removing device, the refrigerant flow path has a porous body, and the porosity of the refrigerant flow path is in the vicinity of a portion that separates the refrigerant flow path from the catalyst reaction layer adjacent thereto, The refrigerant flow path is configured to be different in the vicinity of the central axis.
[0008]
Alternatively, in a heat exchanger that performs heat exchange between a high-temperature source and a low-temperature fluid including a liquid phase, the low-temperature fluid channel that circulates the low-temperature fluid is configured to be porous, and the porosity of the low-temperature fluid channel is set to It changes according to the distance from the said high temperature source adjacent to a low temperature fluid flow path.
[0009]
Alternatively, the catalytic reaction apparatus includes a catalytic reaction layer that generates a reaction with heat generation, and a refrigerant flow path that has a porous body and is configured adjacent to the catalytic reaction layer so that heat can be exchanged by circulating the refrigerant. . A liquid refrigerant is always brought into contact with the vertical lower end of the porous body.
[0010]
[Action and effect]
A catalyst reaction layer that generates a reaction accompanied by heat generation, and a refrigerant flow path that has a porous body and is configured adjacent to the catalyst reaction layer so as to be able to exchange heat, and the porosity of the refrigerant flow path from the catalyst reaction layer Change according to the distance. As a result, when the refrigerant evaporates, the evaporated refrigerant can be preferentially circulated in a portion having a large porosity, and the evaporated refrigerant can be quickly discharged from the refrigerant flow path. As a result, when the volume of the refrigerant suddenly increases due to evaporation, the refrigerant can be supplied smoothly and stress generated in the catalytic reaction apparatus can be suppressed.
[0011]
Vapor generation means for generating water vapor or fuel vapor using heat generated in the catalytic reaction layer, and as a carbon monoxide removal device, the refrigerant flow path has a porous body, and the porosity of the refrigerant flow path is It is configured to be different in the vicinity of the portion separating the refrigerant flow path and the catalytic reaction layer and in the vicinity of the central axis of the refrigerant flow path. As a result, when the volume of the refrigerant suddenly increases due to evaporation, the refrigerant can be smoothly supplied to the carbon monoxide removing device, and the heat generated in the carbon monoxide removing device can be used efficiently. be able to.
[0012]
The low-temperature fluid flow path through which the low-temperature fluid flows is configured to be porous, and the porosity of the low-temperature fluid flow path is changed according to the distance from the high-temperature source adjacent to the low-temperature fluid flow path. As a result, when the low-temperature fluid evaporates, the low-temperature fluid that has evaporated to a portion with a large porosity can be preferentially circulated, and the low-temperature fluid that has evaporated from the low-temperature fluid channel can be quickly discharged. As a result, when the volume of the low temperature fluid increases rapidly due to evaporation, the low temperature fluid can be supplied smoothly and the stress generated in the heat exchanger can be suppressed.
[0013]
A liquid refrigerant is brought into contact with the lower end in the vertical direction of the porous body. Thereby, the driving force for supplying a refrigerant | coolant becomes unnecessary or can be reduced by capillary action.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment will be described. Here, a fuel cell system mounted on an automobile or the like as a drive source will be described. A schematic configuration of the fuel cell system is shown in FIG.
[0015]
The fuel cell system includes a fuel reforming system that generates reformed gas from a hydrocarbon-based fuel such as gasoline in order to generate hydrogen used for power generation. The fuel reforming system includes a reformer 3 having a reforming catalyst that causes a reforming reaction using fuel vapor, water vapor, and oxidant gas (air). Here, the reformer 3 is a catalytic reactor that performs ATR (Auto Thermal Reforming).
[0016]
The reformed gas generated by the reformer 3 contains carbon monoxide (hereinafter referred to as CO) that causes power generation in the stack 8 to be described later. Therefore, a catalyst reactor for reducing the CO concentration in the reformed gas is provided on the upstream side of the stack 8. Here, a shift reactor 4 and a CO remover 5 are provided as catalyst reactors.
[0017]
In the shift reactor 4, water and CO mixed in the reformed gas react upstream of the shift reactor 4 to react with hydrogen and carbon dioxide (hereinafter referred to as CO 2). ₂ ) Is generated. Further, in the CO remover 5, the oxidant mixed in the upstream side of the CO remover 5, here air and CO react to react with each other. ₂ Is generated. Thereby, the reformed gas in which the CO concentration is reduced to, for example, 10 ppm or less is generated.
[0018]
A stack 8 that generates power using the reformed gas and the oxidant gas (air) generated in this way is provided. Here, for example, a solid polymer electrolyte fuel cell is used. In the stack 8, an electromotive force is generated by protons moving through an electrolyte membrane (not shown). At this time, the transferred protons and oxygen in the air are combined to generate water.
[0019]
In such a fuel cell system, in order to maintain the reaction in each catalytic reactor, it is necessary to maintain the catalyst in the catalytic reactor at an active temperature. For example, the CO remover 5 is provided with a temperature adjustment system for maintaining the CO remover 5 at the catalyst activation temperature in order to generate heat with the oxidation reaction of CO. Here, a pure water system 15 for circulating pure water is provided as a temperature adjustment system. The CO remover 5 is configured as a heat exchangeable catalyst device, and pure water flowing through the pure water system 15 is circulated through the heat exchange section of the CO remover 5, thereby maintaining the CO remover 5 at an appropriate temperature. In FIG. 1, when the fluid flowing through the pure water system 15 is liquid pure water, it is indicated by a dotted line, and when the fluid flowing in the pure water system is vapor phase pure water, it is indicated by a dashed line.
[0020]
The pure water system 15 includes a water tank 7 that stores pure water. As described above, the water generated in the stack 8 along with the power generation is collected in the water tank 7. Liquid pure water taken out from the water tank 7 is supplied into the CO remover 5. When pure water flows through the CO remover 5, at least a part of the pure water evaporates to generate water vapor. Gas-liquid two-phase pure water discharged from the CO remover 5 is supplied to an evaporator, a gas-liquid separator, or the like (not shown) to generate water vapor consisting of a gas phase, and the reformer 3 or shifter. Feed to reactor 4. Note that if the pure water discharged from the CO remover 5 is in a gas phase one-phase state, it is not always necessary to provide an evaporator, a gas-liquid separator, or the like.
[0021]
However, in such a fuel reforming system, there is a possibility that the volume of pure water suddenly increases due to evaporation of pure water in the CO remover 5. As a result, the pressure in the CO remover 5 is increased, and extra stress is generated in the CO remover 5 itself. In addition, when the supply of air, water, or fuel is stopped immediately after the operation is stopped, the supply of water used for the reforming reaction and the shift reaction is stopped, so that the water supply for adjusting the temperature of the CO remover 5 is stopped. Is also stopped. As a result, the amount of heat accumulated in the CO remover 5 is not removed, and the temperature of the CO remover 5 itself rises as shown in FIG. As a result, the catalyst carried on the CO remover 5 exceeded the allowable range, and the catalyst was dissolved to cause deterioration due to an increase in the catalyst particle size, possibly resulting in death.
[0022]
Therefore, in the present embodiment, the CO remover 5 is configured as follows.
[0023]
A schematic configuration of the entire CO remover 5 is shown in FIG. Details of the refrigerant flow path 13 are shown in FIG. FIG. 4 shows a cross-sectional view in the direction including the refrigerant inlet 12 and the refrigerant outlet 11 of the CO remover 5. In the cross-sectional view shown in FIG. 4, the reformed gas flows through the catalyst layer 14 from the front to the back in the direction perpendicular to the paper surface.
[0024]
A refrigerant inlet 12 serving as an inlet portion of pure water taken out from the water tank 7 is provided in a lower portion of the CO remover 5. In addition, a supply manifold 25 a that distributes pure water supplied from the refrigerant inlet 12 to a refrigerant flow path 13 to be described later is provided in a lower portion of the CO remover 5. Moreover, it becomes a heat exchange part and is provided with the refrigerant | coolant flow path 13 which is a flow path of the several pure water arrange | positioned in parallel. Here, pure water flows through the refrigerant flow path 13 from vertically downward to upward. The lower end of the refrigerant flow path 13 communicates with the supply manifold 25a, and the supply manifold 25a communicates with the water tank 7. That is, the lower end of the refrigerant flow path 13, in other words, the lower end of the porous body 18 provided in the refrigerant flow path 13, as will be described later, is configured to always contact the refrigerant from the water tank 7.
[0025]
In addition, a discharge manifold 25 b that collects the gas-liquid two-phase refrigerant from each refrigerant flow path 13 and a refrigerant outlet 11 that discharges the collected refrigerant are provided in the upper part of the CO remover 5. Furthermore, a plurality of parallel catalyst layers 14 that circulate the reformed gas in a direction orthogonal to the refrigerant flow path 13 are provided. The refrigerant flow paths 13 and the catalyst layers 14 are alternately configured. The refrigerant flow path 13 and the catalyst layer 14 are separated by a partition plate 21. Here, the partition plate 21 is configured using a material having good heat conductivity.
[0026]
The pure water absorbs the heat of the reformed gas itself and the heat generated by the oxidation reaction of the reformed gas generated in the catalyst layer 14 when flowing through the refrigerant flow path 13. The catalyst layer 14 is maintained at the activation temperature by this heat exchange. At this time, when the heat for the latent heat is obtained in the pure water, the refrigerant changes phase from liquid to gas and becomes a gas-liquid two-phase state.
[0027]
Next, details of the refrigerant flow path 13 and heat exchange will be described with reference to FIG.
[0028]
The catalyst layer 14 includes a heat transfer expansion plate 22 having a honeycomb structure extending in the flow direction of the reformed gas. The heat transfer expansion plate 22 is configured using a metal flat plate. The heat transfer expansion plate 22 carries an oxidation catalyst. By providing the heat transfer expansion plate 22, the contact area of the reformed gas is increased, the oxidation reaction is promoted, and the heat transfer surface is expanded. The catalyst layer 14 may have a structure in which fins are provided in the flow path.
[0029]
A coolant channel 13 is formed between the catalyst layers 14. The refrigerant flow path 13 includes a porous body 18. Here, the porous body 18 is formed in a portion close to the catalyst layer 14. That is, the porous body 18 is provided adjacent to the partition plate 21. The porous body 18 is made of metal. Further, a vapor channel 19 constituted by a space is provided in the vicinity of the central axis of the refrigerant channel 13 away from the catalyst layer 14. Alternatively, a porous body having a high porosity may be provided near the central axis of the refrigerant flow path 13 to form the vapor flow path 19, and a porous body 18 having a relatively low porosity may be provided on the catalyst layer 14 side. . In other words, the refrigerant flow path 13 is configured so that the porosity in the vicinity of the central axis is larger than that on the catalyst layer 14 side. In addition, the case where “the porosity is large” includes the case where “the porous body does not exist”.
[0030]
Pure water having a temperature lower than the saturation temperature is supplied to the refrigerant flow path 13 configured as described above from the lower part. The pure water in the liquid state flows upward in the porous body 18 by capillary action. At this time, heat exchange is performed between the pure water flowing through the porous body 18 and the catalyst layer 14 to heat the pure water. The pure water, that is, the water vapor that has become a gas phase by obtaining latent heat by this heat exchange, rises through the portion of the refrigerant passage 13 where the porosity is large. That is, water vapor moves from the porous body 18 to the vapor channel 19 and rises in the vapor channel 19. At this time, since pure water in a vapor state flows in the steam channel 19, the water vapor is quickly discharged from the refrigerant channel 13.
[0031]
Here, in order to improve the generation of water vapor, the pure water supplied to the refrigerant flow path 13 is set to a saturated liquid or a state close to saturation. Therefore, the temperature of the pure water is set to the saturation temperature or the saturation temperature. It is preferable that the temperature be adjusted to a temperature close to the saturation temperature. Therefore, it is preferable to provide a means for adjusting the temperature of pure water upstream of the refrigerant inlet 12 of the CO remover 5.
[0032]
In addition, the temperature of the catalyst layer 14 is adjusted by flowing pure water through the porous body 18 by capillary action. However, when the supply of water is insufficient only by the driving force of the capillary action, the driving force from the outside is applied. You may use it auxiliary. Further, when it is necessary to adjust the temperature by supplying more pure water, such as when the temperature of the catalyst layer 14 is abnormally increased, the pure water is supplied to the steam channel 19 by an external driving force. It can also be made. Thereby, deterioration of a catalyst can be prevented reliably.
[0033]
Further, the porous body 18 may be composed of a plurality of layers having different porosity. In this case, the porous body in the portion closest to the catalyst layer 14 has the lowest porosity, and the porosity increases as the distance from the catalyst layer 14 increases. Thereby, the movement of the water vapor becomes smooth, and it is possible to prevent the heat exchange efficiency from being lowered due to the water vapor remaining in the vicinity of the catalyst layer 14 where the heat exchange is most actively performed.
[0034]
Next, the effect of this embodiment will be described.
[0035]
A catalyst layer 14 that generates a reaction with heat generation and a porous body 18 are provided, and a refrigerant channel 13 that is configured adjacent to the catalyst layer 14 so as to be capable of heat exchange is provided. It changes according to the distance from 14. Here, the porous body 18 is disposed on the catalyst layer 14 side, and a space having a lower air efficiency than the porous body 18 is provided on the side away from the catalyst layer 14. As a result, when the refrigerant, here pure water, evaporates, the water vapor can be preferentially circulated through the portion having a large porosity, and the water vapor can be quickly discharged from the refrigerant flow path 13. As a result, when the volume of pure water rapidly increases due to evaporation, the refrigerant can be supplied smoothly and stress generated in the CO remover 5 can be suppressed. Moreover, since the porosity is made different in the positional relationship with the catalyst layer 14, an appropriate heat exchange can be performed by passing an amount of the refrigerant according to the heat received by the refrigerant. Furthermore, since the capillary body phenomenon is caused by providing the porous body 18, the driving force for supplying water is unnecessary or can be reduced. Further, by using the porous body 18, the heat transfer area is increased about three times as compared with the fin type and the heat exchange efficiency is increased, so that the entire volume can be reduced.
[0036]
In the refrigerant channel 13, the porosity on the central axis side of the refrigerant channel 13 is configured to be larger than the vicinity of the portion separating the refrigerant channel 13 and the catalyst layer 14. Here, a porous body 18 is configured in the vicinity of a portion separating the refrigerant flow path 13 and the catalyst layer 14, and a vapor flow path 19 including a space is formed on the central axis side of the refrigerant flow path 13. Thereby, even if pure water evaporates and the volume rapidly increases, water vapor can be released, and the refrigerant can be supplied smoothly.
[0037]
The refrigerant supplied to the refrigerant flow path 13 is in a liquid phase or a two-phase state of a liquid phase and a gas phase. When the supplied refrigerant is in a liquid phase or a two-phase state, the refrigerant may be vaporized in the refrigerant flow path 13. That is, the refrigerant may be in a two-phase state in the refrigerant flow path 13. In such a case, if the refrigerant flow path 13 is composed only of the porous body 18 having a uniform porosity, a gas phase is formed in the catalyst layer 14 where heat transfer is most actively performed, and thus heat transfer. There is a risk of reducing efficiency. Therefore, as in the present embodiment, by changing the air efficiency according to the distance from the catalyst layer 14, the gas phase flows through a portion having a large porosity, so that a decrease in heat transfer efficiency can be suppressed. .
[0038]
Further, the lower end of the porous body 18 in the vertical direction is always in contact with liquid pure water. Thereby, by bringing pure water into contact with the lower end portion of the porous body 18, pure water can be supplied by capillary action, and driving force can be suppressed or made unnecessary from the outside for supplying pure water. it can. Moreover, regardless of the operation / stop of the fuel reforming system, the refrigerant can be always supplied and the abnormal temperature rise of the CO remover 5 can be prevented.
[0039]
The porous body 18 is made of metal. By making the porous body 18 a metal instead of a ceramic, the thermal conductivity is improved and the heat exchange efficiency is improved. For example, the thermal conductivity can be increased by a factor of about 5 compared to ceramics, and the overall volume can be further reduced.
[0040]
Further, the refrigerant inlet 12 side of the refrigerant flow path 13 is configured to be vertically lower than the refrigerant outlet 11 side. Thereby, since the refrigerant | coolant vapor | steam produced | generated by heat exchange becomes easy to be discharged | emitted, a refrigerant | coolant can be supplied more smoothly.
[0041]
Here, a selective oxidation reaction of CO in the hydrogen-rich gas occurs in the catalyst layer 14. That is, the configuration as described above can be applied to the CO remover 5. Thereby, in the CO remover 5, it is possible to prevent the supply of the refrigerant from being smoothly performed due to the evaporation of the refrigerant or the catalyst layer 14 from being deteriorated due to excessive temperature rise.
[0042]
Moreover, the reformer 3 which produces | generates reformed gas at least using water and fuel is provided. Moreover, the CO remover 5 provided with the catalyst layer 14 which reduces CO in reformed gas, and the refrigerant | coolant flow path 13 which heat-exchanges with the catalyst layer 14 using a refrigerant | coolant is provided. Furthermore, a steam generating means for generating steam using heat generated in the catalyst layer 14, here, a pure water system 15 is provided. The generated steam is supplied to the reformed gas 3. Alternatively, the generated water vapor may be supplied to the shift reactor 4. Alternatively, fuel vapor may be generated using heat generated in the catalyst layer 14 and introduced into the reformer 3. The refrigerant passage 13 of the CO remover 5 has a porous body 18, and the porosity of the refrigerant passage 13 is in the vicinity of a portion separating the refrigerant passage 13 and the catalyst layer 14 adjacent thereto, and the refrigerant passage The configuration is different in the vicinity of 13 central axes. Thereby, when the volume of the refrigerant suddenly increases due to evaporation, the refrigerant can be smoothly supplied to the CO remover 5 and the heat generated in the CO remover 5 can be used efficiently.
[0043]
Pure water is used as the refrigerant flowing through the refrigerant flow path 13, and water is generated by exchanging heat between the refrigerant flow path 13 and the catalyst layer 14. Alternatively, fuel vapor may be generated using fuel as the refrigerant. Thereby, it is possible to generate water vapor or fuel vapor using the heat generated in the CO remover 5 with a simple configuration, thereby improving the thermal efficiency.
[0044]
A catalyst layer 14 that generates a reaction accompanied by heat generation and a porous body 18 are provided, and a refrigerant flow path 13 that is adjacent to the catalyst layer 14 so as to be able to exchange heat by circulating the refrigerant is provided. A liquid refrigerant is always brought into contact with the vertical lower end of the porous body 18. Thereby, the driving force for supplying a refrigerant | coolant becomes unnecessary or can be reduced by capillary action. In addition, even when the refrigerant is circulated using an external drive device during normal operation and when the external drive device is stopped, water can be supplied to the porous body 18, so that the catalyst layer 14 is excessive. It is possible to prevent the temperature from rising.
[0045]
Here, although the heat transfer expansion plate 22 is provided in the catalyst layer 14, the porous body 20 can also be provided as shown in FIG. The catalyst layer 14 is formed by filling the porous body 20 supporting the catalyst. In this way, by forming the catalyst layer 14 with the porous body 20 carrying the catalyst, the filling of the catalyst can be made spatially uniform, so that the heat of reaction can be made uniform. Further, since the heat transfer area can be further expanded, heat transfer from the catalyst layer 14 to the refrigerant flow path 13 is smoothly performed, and the entire volume can be reduced.
[0046]
Alternatively, in this embodiment, the temperature of the CO remover 5 is adjusted by the pure water system 15, but a cooling system may be provided separately from the pure water system 15. For example, a refrigerant system 16 is provided as shown in FIG. By performing heat exchange between the refrigerant circulating in the refrigerant system 16 and the CO remover 5, the CO remover 5 is adjusted to an appropriate temperature. The refrigerant system 16 includes a heat exchanger 6. The heat exchanger 6 performs heat exchange between the refrigerant and the pure water of the pure water system 15, thereby adjusting the temperature of the refrigerant and thus the CO remover 5. Pure water taken out from the water tank 7 is supplied to the heat exchanger 6 to generate water vapor by exchanging heat with the refrigerant and used for reforming reaction, shift reaction, and the like. That is, the steam generation means may be configured by combining the refrigerant system 16 and the pure water system 15.
[0047]
Further, here, the CO remover 5 is used as the catalytic reaction apparatus, but this is not restrictive. For example, a shift reactor 4 can be used. Alternatively, when the reformer 3 requires a cooling system, the reformer 3 may be applied. That is, the present invention can be applied to a catalytic reaction apparatus in which vaporization of refrigerant occurs when temperature adjustment is performed.
[0048]
Next, a second embodiment will be described. Hereinafter, a description will be given centering on differences from the first embodiment.
[0049]
The configuration of the fuel cell system is the same as that of the first embodiment. A schematic configuration of the CO remover 5 is shown in FIG.
[0050]
Here, the CO remover 5 is provided with a reservoir tank 17. Here, the reservoir tank 17 may be the same as the water tank 7. However, when the large water tank 7 cannot be disposed in the vicinity of the CO remover 5 due to the layout, a small reservoir tank 17 is provided separately from the water tank 7.
[0051]
A reservoir tank 17 is provided upstream of the refrigerant inlet 12. A refrigerant, here pure water, is stored in the reservoir tank 17. The coolant level in the reservoir tank 17 is configured to be above the lower end in the vertical direction of the porous body 18 provided in the CO remover 5. Alternatively, the flow rate of pure water in the reservoir tank 17 is adjusted so that the liquid level of the refrigerant in the reservoir tank 17 is above the lower end in the vertical direction of the porous body 18 provided in the CO remover 5. Further, the lower end of the porous body 18 in the vertical direction is always in contact with liquid pure water. Here, the lower part of the reservoir tank 17 and the supply manifold 25a are connected.
[0052]
Next, the effect of this embodiment will be described. Only the effects different from those of the first embodiment will be described below.
[0053]
A reservoir tank 17 for storing a liquid refrigerant is provided upstream of the refrigerant flow path 13. Thereby, it is possible to always supply water regardless of whether the reforming system is operated or stopped, and an abnormal temperature rise of the CO remover 5 can be prevented.
[0054]
Here, the lower end in the vertical direction of the porous body 18 and the reservoir tank 17 are connected to each other, and the liquid level of the refrigerant stored in the reservoir tank 17 is on the upper side in the vertical direction from the lower end in the vertical direction of the porous body 18. To do. Thereby, the refrigerant which performs heat exchange can always be brought into contact with the vertical lower surface of the porous body 18.
[0055]
Next, a third embodiment will be described. Hereinafter, a description will be given centering on differences from the second embodiment.
[0056]
The configuration of the fuel cell system is the same as that of the first embodiment. A schematic configuration of the CO remover 5 is shown in FIG. Similar to the second embodiment, a reservoir tank 17 is provided on the upstream side of the refrigerant inlet 12. Further, the liquid level of the refrigerant is configured to be higher than the lower end of the porous body 18.
[0057]
A heat exchanger 29 is provided between the reservoir tank 17 and the supply manifold 25a. A gas-liquid separator 23 is provided downstream of the discharge manifold 25b. Here, the gas-liquid separator 23 is arranged on the downstream side of the refrigerant outlet 11. That is, the heat exchanger 29 is disposed below the porous body 18. Further, the gas-liquid separator 23 is disposed above the porous body 18.
[0058]
Pure water stored in the reservoir tank 17 is supplied to the heat exchanger 29. Here, the pure water is adjusted to a temperature lower than the saturation temperature and close to the saturation temperature. By supplying this directly to the supply manifold 25 a and the refrigerant flow path 13, it is possible to suppress heat radiation when flowing through the piping and the like, and it is possible to supply pure water whose temperature is accurately adjusted to the refrigerant flow path 13. As a result, it is possible to efficiently generate heat and generate water vapor.
[0059]
Pure water becomes a gas-liquid two-phase flow by partially evaporating in the refrigerant flow path 13. This gas-liquid two-phase flow is supplied to the gas-liquid separator 23 and separated into a gas phase and a liquid phase. The separated gas phase is supplied to the reformer 3 and the shift reactor 4 and used for the reaction. On the other hand, the separated pure water in the liquid phase is collected in the reservoir tank 17 by the pump 24.
[0060]
Next, the effect of the present invention will be described. Hereinafter, only effects different from those of the first and second embodiments will be described.
[0061]
A gas-liquid separation device 23 that performs gas-liquid separation of the refrigerant is provided on the downstream side of the refrigerant flow path 13, and the liquid refrigerant separated by the gas-liquid separation device 23 is collected in the reservoir tank 17. In this way, the pure water introduced into the refrigerant flow path 13 of the CO remover 5 can be preheated in advance by returning the liquid water having the saturation temperature that has not been vaporized to the reservoir tank 17. As a result, pure water is easily evaporated in the refrigerant flow path 13, and water vapor can be generated efficiently.
[0062]
In addition, a gas-liquid separation device 23 that gas-liquid separates the refrigerant that has passed through the refrigerant channel 13 is provided. Gaseous refrigerant separated by the gas-liquid separator 23 is supplied to the reformer 3. Alternatively, the gaseous refrigerant separated by the gas-liquid separation layer 23 is supplied to the shift reactor 4. Thereby, since only water vapor | steam can be supplied to the reformer 3, reaction and temperature management in the reformer 3 can be made easy.
[0063]
Next, a fourth embodiment will be described. A schematic configuration of the fuel cell system is shown in FIG. Hereinafter, a description will be given centering on portions different from the first embodiment.
[0064]
The shift reactor 4 is composed of a plurality of stages. Further, the CO remover 5 is constituted by a plurality of stages. Here, the shift reactor 4 is composed of an upstream shift reactor 4a and a downstream shift reactor 4b, and the CO remover 5 is composed of an upstream CO remover 5a and a downstream CO remover 5b. Here, the reactants used in the reactors 4 and 5 are mixed immediately upstream of the reactors 4 and 5. That is, steam is mixed into the reformed gas on the upstream side of each of the upstream shift reactor 4a and the downstream shift reactor 4b. In addition, on the upstream side of each of the upstream side CO remover 5a and the downstream side CO remover 5b, an oxidizing agent, here air, is mixed into the reformed gas.
[0065]
As the upstream shift reactor 4a and the downstream shift reactor 4, in the CO remover 5 used in the first embodiment, the catalyst filled in the catalyst layer 14 is replaced with a catalyst that promotes the shift reaction. Use. That is, the shift reactors 4a and 4b have a structure in which pure water used for temperature adjustment is supplied by capillary action without requiring an external driving device.
[0066]
A heat exchanger 28 a is provided on the downstream side of the reformer 3, and a heat exchanger 28 b is provided on the downstream side of the CO remover 5. Further, a combustor 27 is provided on the downstream side of the stack 8. A fuel tank 26 for storing liquid reformed fuel is also provided.
[0067]
Fuel vapor is generated by exchanging heat between the liquid fuel stored in the fuel tank 26 and the combustor 27. In the combustor 27, the exhaust gas of the stack 8 is burned as will be described later. Fuel vapor, air, and steam generated by the heat exchanger 28a as described later are supplied to the reformer 3 to generate reformed gas. At this time, the temperature of the reformed gas is higher than the activation temperature of the catalyst held in the shift reactor 4. Therefore, the reformed gas temperature is lowered by supplying the reformed gas to the heat exchanger 28a and exchanging heat with the pure water introduced from the water tank 7.
[0068]
Further, the reformed gas is supplied to the shift reactor 4. In the upstream shift reactor 4a and the downstream shift reactor 4b, the CO concentration is reduced by the reaction of water vapor and CO mixed in each upstream side. The reformed gas discharged from the shift reactor 4 is supplied to the CO remover 5. In the upstream CO remover 5a and the downstream CO remover 5b, the oxygen concentration in the air mixed on the upstream side reacts with CO to reduce the CO concentration.
[0069]
The reformed gas having such a low CO concentration is circulated through the heat exchanger 28b. Here, the reaction temperature of the stack 8, which is a solid polymer fuel cell, is set lower than the catalyst activation temperature held in the CO remover 5. Therefore, the reformed gas temperature is lowered in the heat exchanger 28b and then supplied to the stack 8. Exhaust gas discharged from the stack 8 without being used for power generation is supplied to the combustor 27 for combustion treatment. Steam generated for use in the reforming reaction is generated from the liquid fuel using the heat generated at this time.
[0070]
Next, the pure water system 15 will be described.
[0071]
The flow rate-adjusted pure water is supplied from the water tank 7 to the heat exchanger 28a. In the heat exchanger 28a, as described above, steam is generated by performing heat exchange between the high-temperature reformed gas generated in the reformer 3 and pure water, and used for the reforming reaction.
[0072]
The pure water whose flow rate is adjusted is supplied from the water tank 7 to the heat exchanger 28b. In the heat exchanger 28b, as described above, the temperature of pure water is raised by performing heat exchange between the reformed gas discharged from the CO remover 5 and pure water.
[0073]
Further, pure water is supplied to the downstream CO remover 5b. In the downstream CO remover 5b, pure water is heated by absorbing the heat of the reformed gas itself and the heat accompanying the CO selective oxidation reaction. At this time, when heat corresponding to the latent heat of water is absorbed, pure water is in a gas-liquid two-phase flow state. Furthermore, pure water is supplied to the upstream CO remover 5a and heated.
[0074]
The pure water whose temperature has been increased in this way is supplied to the shift reactor 4. Here, after the temperature of pure water is raised in advance in the CO remover 5, pure water is supplied to the shift reactor 4. Thereby, when flowing through the refrigerant flow path 13 in the shift reactor 4, water vapor can be efficiently generated.
[0075]
Pure water is branched into the upstream shift reactor 4a side and the downstream shift reactor 4b side. Here, this branching ratio is the ratio of the amount of pure water used for the shift reaction in each shift reactor 4a, 4b. The pure water branched to the upstream shift reactor 4a side is supplied to the refrigerant flow path 13 of the upstream shift reactor 4a. Here, as in the first embodiment, the pure water flowing through the porous body 18 absorbs the heat of the reformed gas supplied to the catalyst layer 14 and the heat generated by the shift reaction, Water vapor is generated. The generated water vapor is discharged through the vapor channel 19 having a large porosity. The same applies to the downstream shift reactor 4b.
[0076]
In this way, the steam generated in the upstream shift reactor 4a is mixed into the reformed gas from the upstream side of the shift reactor 4a. Further, the steam generated in the downstream shift reactor 4b is mixed into the reformed gas from the upstream side of the downstream shift reactor 4b. The reformed gas mixed with water vapor is supplied to the shift reactor 4a or 4b to cause a shift reaction.
[0077]
The pure water flow path in the heat exchanger 28a can have the same configuration as the refrigerant flow path 13 shown in the first embodiment. In this case, the porosity of the porous body 18 is changed according to the distance from the reformed gas flow path through which the reformed gas flows. The porosity increases with increasing distance from the reformed gas flow path. For example, the portion near the central axis of the pure water flow path is constituted by a space.
[0078]
Next, the effect of this embodiment will be described. Hereinafter, only effects different from those of the first to third embodiments will be described.
[0079]
The catalyst layer 14 is filled with a catalyst that promotes the shift reaction. That is, the shift reactor 4 can be used as a catalytic reactor. In this case, the deionized water temperature can be raised in advance by supplying the deionized water that has circulated in the CO remover 5 as the refrigerant to the shift reactor 4 as the refrigerant. As a result, the generation efficiency of water vapor can be improved. In addition, by heating the pure water in the CO remover 5 in advance, when the shift reactor 4 is composed of a plurality of stages, the pure water is supplied in parallel to the plurality of shift reactors 4a and 4b. Can do. As a result, heat is easily supplied to the entire pure water in the shift reactor 4, and water vapor can be generated more efficiently.
[0080]
Further, in the heat exchanger 28a that performs heat exchange between the high-temperature source (reformed gas) and the low-temperature fluid (pure water) including the liquid phase, the pure water flow path for flowing the pure water is configured to be porous, and the pure water flow path The porosity of (refrigerant flow path 13) is changed according to the distance from the reformed gas. Thereby, when pure water evaporates, water vapor can be preferentially circulated through a portion having a large porosity, and water vapor can be quickly discharged from the pure water flow path. As a result, when the volume of pure water increases rapidly due to evaporation, pure water can be supplied smoothly and stress generated in the heat exchanger 28a can be suppressed. Further, it is possible to smoothly take out the water vapor from the heat exchanger 28a.
[0081]
In the first to third embodiments, the CO remover 5 may be configured by a plurality of stages as in the fourth embodiment. Moreover, you may provide each heat exchanger 28a, 28b. Furthermore, in the fourth embodiment, the configuration of the shift reactors 4a and 4b may be the configuration of the CO remover 5 used in the second and third embodiments. However, the catalyst layer 3 carries a catalyst that promotes the shift reaction. In the fourth embodiment, the CO removers 5 a and 5 b used in any of the first to third embodiments can be used, and water vapor can be used as the refrigerant of the shift reactor 4.
[0082]
Thus, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a schematic view of a fuel cell system used in a first embodiment.
FIG. 2 is a view showing a temperature change of a catalyst of the CO remover used in the first embodiment.
FIG. 3 is an external view of a CO remover used in the first embodiment.
FIG. 4 is a schematic view of a refrigerant flow path of a CO remover used in the first embodiment.
FIG. 5 is a diagram showing the configuration and operation of the refrigerant flow path of the CO remover used in the first embodiment.
FIG. 6 is a diagram showing another example of the configuration and operation of the refrigerant flow path of the CO remover used in the first embodiment.
FIG. 7 is a schematic view of another example of the fuel cell system used in the first embodiment.
FIG. 8 is a schematic view of a CO remover used in the second embodiment.
FIG. 9 is a schematic view of a CO remover used in the third embodiment.
FIG. 10 is a schematic view of a fuel cell system used in a fourth embodiment.
[Explanation of symbols]
3 Reformer (reforming reactor)
4 Shift reactor
4a Upstream shift reactor (catalytic reactor)
4b Downstream shift reactor (catalytic reactor)
5 CO remover (catalytic reactor)
11 Refrigerant outlet
12 Refrigerant inlet
15 Pure water system (steam generation means)
16 Cooling system (steam generation means)
17 Reservoir tank
18 Porous material
19 Steam flow path
20 Porous material
23 Gas-liquid separation device (gas-liquid separation means)
28a heat exchanger

Claims (16)

A catalytic reaction layer that generates an exothermic reaction;
Having a porous body and comprising a refrigerant flow path configured adjacent to the catalytic reaction layer so as to allow heat exchange;
A catalytic reaction apparatus, wherein the porosity of the refrigerant flow path is changed according to a distance from the catalytic reaction layer. 2. The catalytic reaction according to claim 1, wherein a porosity on a central axis side of the refrigerant flow path is larger in the refrigerant flow path than in the vicinity of a portion separating the refrigerant flow path and the catalytic reaction layer. apparatus. The catalytic reaction apparatus according to claim 1 or 2, wherein the refrigerant supplied to the refrigerant flow path is in a liquid phase or a two-phase state of a liquid phase and a gas phase. The catalytic reaction apparatus according to any one of claims 1 to 3, wherein the lower end in the vertical direction of the porous body is always in contact with a liquid refrigerant. The catalytic reaction apparatus according to any one of claims 1 to 4, wherein the porous body is made of metal. The catalytic reaction apparatus according to any one of claims 1 to 5, further comprising a reservoir tank that stores a refrigerant in a liquid state upstream of the refrigerant flow path. Gas-liquid separation means for performing gas-liquid separation of the refrigerant is provided on the downstream side of the refrigerant flow path,
The catalytic reaction apparatus according to claim 6, wherein the refrigerant in a liquid state separated by the gas-liquid separation unit is collected in the reservoir tank. Communicating the lower end in the vertical direction of the porous body and the reservoir tank;
The catalytic reaction apparatus according to claim 6 or 7, wherein a liquid level of the refrigerant stored in the reservoir tank is above the vertical direction from the lower end in the vertical direction of the porous body. The catalytic reaction device according to any one of claims 1 to 8, wherein a refrigerant inlet side of the refrigerant flow path is configured to be vertically lower than a refrigerant outlet side. The catalytic reaction apparatus according to any one of claims 1 to 9, wherein the catalytic reaction layer is formed of a porous body supporting a catalyst. The catalytic reaction apparatus according to any one of claims 1 to 10, wherein a selective oxidation reaction of carbon monoxide in a hydrogen-rich gas is generated in the catalytic reaction layer. A reforming reactor that generates reformed gas using at least water and fuel;
A carbon monoxide removal device comprising: a catalytic reaction layer that reduces carbon monoxide in the reformed gas; and a refrigerant flow path that performs heat exchange with the catalytic reaction layer using a refrigerant;
Steam generating means for generating steam or fuel vapor using heat generated in the catalytic reaction layer, and
Having a porous body in the refrigerant flow path of the carbon monoxide removal apparatus,
A fuel characterized in that the porosity of the refrigerant flow path is different in the vicinity of a portion separating the refrigerant flow path from the catalyst reaction layer adjacent thereto and in the vicinity of the central axis of the refrigerant flow path. Reforming system. The fuel according to claim 12, wherein pure water or liquid fuel is used as a refrigerant flowing through the refrigerant flow path, and steam or fuel vapor is generated by performing heat exchange between the refrigerant flow path and the catalytic reaction layer. Reforming system. The fuel reforming system according to claim 13, further comprising gas-liquid separation means for gas-liquid separation of the refrigerant that has passed through the refrigerant flow path. In a heat exchanger that performs heat exchange between a high-temperature source and a low-temperature fluid containing a liquid phase,
The cryogenic fluid passage that circulates the cryogenic fluid is made porous,
The heat exchanger characterized by changing the porosity of the low-temperature fluid channel according to the distance from the high-temperature source adjacent to the low-temperature fluid channel. A catalytic reaction layer that generates an exothermic reaction;
A refrigerant flow path having a porous body and configured adjacent to the catalyst reaction layer so as to allow heat exchange by circulating the refrigerant;
A catalytic reaction apparatus characterized in that a liquid refrigerant is always brought into contact with a lower end in a vertical direction of the porous body.

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