JP2006294297A - Fuel exhaust gas diluting device for fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel exhaust gas diluting device for a fuel cell system without pressure loss or freezing of water or the like inside the device and capable of surely and efficiently diluting the gas to be diluted. <P>SOLUTION: A mixing part mixing diluted gas and diluting gas is provided with a diluting gas guide tube, and a mixture gas exhaust tube for exhausting mixture gas in the diluting gas guide tube and the mixing part. A tube cross-section area of the diluting gas guide tube is expanded toward a part connected to the mixture part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel exhaust gas dilution apparatus for a fuel cell system used for diluting hydrogen gas purged from the fuel cell system.

  In a fuel cell system used as a power source for automobiles and the like, the efficiency of fuel utilization is improved by circulating and reusing hydrogen used as fuel. In such a fuel cell system, in order to prevent the voltage of the fuel cell temporarily lowered or to prevent the differential pressure between both electrodes of the fuel cell from becoming excessive when the vehicle is stopped, It is necessary to perform a purge which is an operation for releasing a part of the system to the outside of the system.

  The gas purged from the circulation system is a gas containing high-concentration hydrogen, and if released into the atmosphere as it is, there is a risk that hydrogen will burn by some kind of fire. Therefore, it is necessary to dilute the purged gas before being released into the atmosphere so that the concentration of hydrogen contained is lower than the combustion limit, and a diluter that dilutes the purge gas is used.

  For example, in Patent Document 1, a stay region in which purged gas is retained, a dilution region in which gas and air purged from the stay region are mixed and diluted, and a purge region is purged from the stay region to the dilution region. There is disclosed a diluting device provided with a flow passage portion through which gas flows. However, this is complicated in structure because it is necessary to connect a part of two partitioned spaces with a flow passage part, and is difficult to manufacture. In addition, this device has many places where gas flows through small holes, such as a flow passage, and moisture accumulates near these holes and freezes at low temperatures, blocking the flow path. There is a possibility that a problem such as end will occur.

  In the conventional diluting apparatus including the diluting apparatus disclosed in Patent Document 1, a straight pipe having a small cross-sectional area is usually used as a pipe for introducing purge gas into the diluting apparatus. When introduced into a dilution container of a diluting device having a significantly large cross-sectional area, there may be a problem that a cross-sectional area of the purge gas flow path rapidly increases. For example, in a general dilution apparatus, the volume of the purge gas introduced into the dilution container rapidly increases because the cross-sectional area of the dilution container is larger than the cross-sectional area of the pipe for introducing the purge gas into the dilution container. However, if the above-mentioned cross-sectional area difference is large, the pressure of the purge gas rapidly decreases and vortices are generated in the purge gas flow. When such a vortex is generated, a significant pressure loss occurs more than the pressure drop due to the cross-sectional area difference, and the pressure inside the circulation system of the fuel cell system and the pressure outside the circulation system (purge gas piping, etc.) The difference between the two becomes small, and the gas in the circulation system becomes difficult to be discharged. Therefore, in order to discharge the gas in the circulatory system without delay, it is necessary to increase the diameter of the opening of the discharge valve from the circulatory system, leading to an increase in the size of the apparatus.

  Further, the purge gas contains moisture, and moves with the purge gas in the state of water vapor when the flow rate is above a certain level. However, since the flow velocity rapidly decreases in the vicinity of the connection portion between the pipe and the dilution container, the moisture in the purge gas may become water droplets and remain in the vicinity of the connection portion. When such a state occurs in a low-temperature atmosphere, there is a possibility that water accumulated in the vicinity of the connection portion freezes and closes the piping.

  Further, in the conventional dilution apparatus, the purge gas and the air used for dilution of the purge gas are often introduced into the dilution container in the same direction from different positions on the same side surface of the dilution container. Therefore, the purge gas is introduced at a location biased with respect to the air flow in the dilution container, and is not sufficiently diluted even in the dilution container, resulting in a bias in the purge gas concentration in the exhaust gas from the dilution container. May end up.

JP 2003-132915 A

  The present invention has been made in view of the above problems, and is free from defects such as pressure loss and moisture freezing in a dilution apparatus, and can be used to efficiently and reliably dilute a gas to be diluted. The main object is to provide an exhaust gas dilution device.

  To achieve the above object, the present invention provides a fuel exhaust gas dilution apparatus for a fuel cell system for mixing a gas to be diluted and a dilution gas, and a mixing unit for mixing the gas to be diluted and the dilution gas, A dilution gas introduction pipe for introducing the dilution gas into the mixing section, a dilution gas introduction pipe for introducing the dilution gas into the mixing section, and a discharge of the mixed gas in the mixing section. A cross-sectional enlargement having a mixed gas discharge pipe, wherein the dilution gas introduction pipe is connected to a dilution gas piping section for introducing the dilution gas into the mixing section, and downstream of the dilution gas piping section The cross-sectional enlarged part has an upstream opening connected to the downstream side of the dilution gas piping part and a downstream opening connected to the mixing part, and the cross-sectional enlarged It is perpendicular to the axis of the diluted gas introduction pipe at the downstream opening of the section. A fuel exhaust gas dilution device for a fuel cell system, wherein a cross-sectional area of a simple cross section is larger than a cross-sectional area of a cross section perpendicular to the axis of the diluted gas introduction pipe of the upstream opening of the cross-sectional enlarged portion provide.

  In the fuel exhaust gas dilution device for a fuel cell system of the present invention (hereinafter sometimes simply referred to as a dilution device), since the cross-sectional enlarged portion is provided in the dilution gas introduction pipe, the dilution gas is provided in the mixing portion. When the gas is introduced, the cross-sectional area of the diluted gas passage gradually increases. Therefore, it is possible to prevent problems such as pressure loss and moisture freezing caused by a sudden increase in the cross-sectional area of the diluted gas flow path. In addition, since the cross-sectional area of the downstream side opening of the cross-sectional enlarged portion, which is the opening through which the gas to be diluted is introduced, is large, there is little bias to the flow of the dilution gas when the gas to be diluted is introduced. The diluted gas can be reliably diluted with the dilution gas.

  In the above-mentioned invention, the cross-sectional area of the cross section perpendicular to the axis of the dilution gas introduction pipe of the cross section enlarged portion continuously increases from the dilution gas pipe section side to the mixing section side. preferable. Since the cross-sectional area of the cross-sectional enlarged portion continuously increases, the cross-sectional area of the diluted gas flow path also gradually increases, so that the above problem can be solved more effectively.

  In the present invention, the mixing portion is provided with an introduction penetrating portion provided at an end portion of the dilution gas introduction pipe, and an introduction pipe opening which is an opening portion is provided at the end portion of the introduction penetration portion. It is preferable that the downstream opening of the dilution gas introduction pipe is provided upstream of the dilution gas flow with respect to the introduction pipe opening. By adopting such a configuration, the dilution gas does not flow directly from the dilution gas introduction pipe to the mixed gas discharge pipe, but becomes a turbulent flow after introduction into the mixed gas discharge pipe in a state where the dilution gas is entrained. Discharged. Therefore, the dilution gas can be more reliably mixed with the dilution gas by retaining the dilution gas in the mixing portion for a long time in a turbulent state and introducing the dilution gas into the turbulent flow.

  The diluting apparatus of the present invention can prevent problems such as pressure loss and freezing of moisture, and has an effect that the gas to be diluted can be diluted efficiently and reliably.

  The diluting device of the present invention is used for diluting a gas containing fuel (hydrogen) discharged from a fuel cell system. For example, a fuel cell system mounted on an automobile or the like as illustrated in FIG. It can be used for dilution of a gas containing hydrogen discharged from the gas. As shown in FIG. 1, the fuel electrode off-gas (diluted gas) discharged from the fuel electrode of the fuel cell system is diluted by a diluting device and then released into the atmosphere.

Hereinafter, the configuration of the dilution apparatus of the present invention will be specifically described with reference to the drawings.
2-4 is a schematic block diagram which shows an example of the dilution apparatus of this invention. As shown in FIGS. 2 to 4, the dilution apparatus 1 of the present invention includes a mixing unit 2 that mixes a dilution gas and a dilution gas, and a dilution gas introduction pipe for introducing the dilution gas into the mixing unit 2. 3, a dilution gas introduction pipe 4 for introducing the dilution gas into the mixing section 2, and a mixed gas discharge pipe 5 for discharging the mixed gas in the mixing section 2 are provided. Further, the dilution gas introduction pipe 3 includes a dilution gas piping portion 6 for introducing the dilution gas into the mixing portion 2 and a cross-sectional enlarged portion 9 connected to the downstream side of the dilution gas piping portion 6. The cross-sectional enlarged portion 9 includes an upstream opening 7 connected to the downstream side of the diluted gas pipe portion 6 and a downstream opening 8 connected to the mixing portion 2. And have. Further, an introduction penetrating part 10 penetrating into the mixing part 2 is provided at the end of the dilution gas introduction pipe 4, and the dilution gas is introduced at the end of the introduction penetrating part 10. It is introduced into the mixing unit 2 from the dilution gas introduction tube 4 through the tube opening 11.

  In the present invention, the cross-sectional enlarged portion 9 is such that the cross-sectional area of the downstream opening 8 that is a connecting portion with the mixing portion 2 is the cross-sectional area of the upstream opening 7 that is a connecting portion with the diluted gas piping portion 6. It is formed so as to be larger. Thus, since the cross-sectional enlarged portion 9 has a shape in which the cross-sectional area increases from the upstream side to the downstream side, the cross-sectional enlarged portion 9 is introduced from the diluted gas pipe portion 6 to the cross-sectional enlarged portion 9 and passes through the cross-sectional enlarged portion 9. The cross-sectional area of the gas flow path of the gas gradually increases, and when the dilution gas is introduced into the mixing unit 2, the cross-sectional area of the gas flow path of the dilution gas further increases. In the present invention, since the gas to be diluted is introduced into the mixing unit 2 with the gas flow path enlarged to some extent, the cross-sectional area of the gas flow path of the gas to be diluted, which occurs in a conventional dilution apparatus, is abrupt. It is possible to prevent problems caused by enlarging. In the present invention, the cross-sectional area means the area of a cross section perpendicular to the axis of the diluted gas introduction pipe 3 if not particularly limited.

  The diluting device of the present invention has the following advantages because the cross-sectional area of the gas flow path of the gas to be diluted is prevented from rapidly expanding when introduced into the mixing unit as described above. . First, since generation | occurrence | production of the vortex in the vicinity of the location where the to-be-diluted gas is introduce | transduced in a mixing part can be prevented, the significant pressure loss accompanying generation | occurrence | production of a vortex can be prevented. As a result, the pressure difference between the inside and outside of the fuel cell system from which the gas to be diluted is discharged can be maintained, and exhaust from the fuel cell system can be performed smoothly, so that the exhaust valve can be downsized.

  In addition, the downstream side opening of the cross-sectional enlarged portion in the present invention is significantly larger than the opening of the dilution gas introduction port in the conventional dilution device, and has a cross-sectional area closer to the cross-sectional area of the mixing portion. The gas to be diluted can be introduced in a state where there is little deviation from the flow of the dilution gas. Thereby, the concentration distribution of the dilution gas can be made uniform even in the vicinity of the dilution gas introduction portion of the mixing portion, and the space in the mixing portion can be effectively utilized. Therefore, it becomes possible to reliably dilute more dilution gas in a narrow space, and even if the amount of dilution gas to be discharged is the same, the mixing section can be made smaller than before, and the dilution device can be made compact. Can be

  Further, in the diluting device of the present invention, it is possible to prevent a rapid decrease in the flow rate accompanying a sudden increase in the cross-sectional area of the gas flow path of the gas to be diluted. It is possible to prevent problems such as adhering to the vicinity of the outlet or freezing of the adhering water to close the diluted gas introduction pipe. In addition, by making the connecting portion between the cross-sectional enlarged portion and the mixing portion rounded, it is possible to more effectively prevent moisture adhesion and the like. In addition, since the cross-sectional area of the downstream opening of the cross-sectional enlarged portion is large, there is little possibility that the downstream opening will be clogged even when moisture adheres, and the diluted gas should be introduced into the mixing portion without delay. Can do.

  In the present invention, the shape of the cross-sectional enlarged portion is such that the cross-sectional area of the downstream opening that is the connecting portion with the mixing portion is larger than the cross-sectional area of the upstream opening that is the connecting portion with the diluted gas piping portion. If it is a shape, it will not specifically limit. For example, as illustrated in FIGS. 5A and 5B, the cross-sectional enlarged portion 9 is provided near the connection portion between the diluted gas introduction pipe 3 and the mixing portion 2, or FIG. As exemplified in c) and (d), there may be mentioned those in which the cross-sectional enlarged portion 9 is formed from the upstream side. Thus, the shape of the cross-sectional enlarged portion 9 in which the cross-sectional area continuously changes is such that the cross-sectional area increases linearly as shown in FIGS. 5A and 5C, and FIGS. As shown in d), the cross-sectional area can be classified as increasing in a curve. Moreover, as illustrated in FIG. 5E, the cross-sectional area may be increased stepwise. Furthermore, the cross-sectional enlarged portion 9 does not have to be symmetrical with respect to the central axis of the diluted gas piping portion, as illustrated in FIG. Of the above shapes, the shape of the cross-sectional enlarged portion 9 used in the present invention is preferably such that the cross-sectional area continuously increases. Thereby, since the cross-sectional area of the gas flow path of the gas to be diluted that passes through the cross-sectional enlarged portion 9 can be gradually enlarged, the effect of the present invention can be further enhanced.

  The cross-sectional area of the downstream opening of the cross-sectional enlarged portion is not particularly limited as long as it is larger than the upstream opening. Further, the cross-sectional area of the downstream opening of the cross-sectional enlarged portion is close to the cross-sectional area of the side surface of the mixing portion on the side where the gas to be diluted is introduced (hereinafter sometimes referred to as the dilution gas introduction side surface). It is preferable that it is a magnitude | size, and it is especially preferable that both cross-sectional areas are equivalent. The gas flow path of the gas to be diluted when it is introduced into the mixing section by setting the cross-sectional area of the upstream side opening, the downstream side opening of the cross section enlarged portion, and the dilution gas introduction side surface of the mixing section within the above range. The cross-sectional area can be gradually increased, and the effects of the present invention as described above can be obtained more reliably.

  In the diluting apparatus of the present invention, the method of introducing the dilution gas into the mixing unit and the method of discharging the mixed gas from the mixing unit, such as the size and shape of the mixing unit, are not particularly limited. The amount of the gas to be diluted and the shape of the space in which the dilution device is installed can be adjusted as appropriate. For example, as disclosed in the above Japanese Patent Application Laid-Open No. 2003-132915, a retention region for retaining purged gas, a dilution region for mixing and diluting the purged gas and air from the retention region, and the retention region The cross-sectional enlarged portion as described above may be provided in a diluting device provided with a flow-through portion for allowing the purged gas to flow from to the dilution region.

  In the present invention, an introduction penetration portion provided at an end portion of the dilution gas introduction pipe is inserted into the mixing portion, and an introduction pipe opening portion which is an opening portion is provided at the end portion of the introduction penetration portion. It is preferable that the downstream opening of the dilution gas introduction pipe is provided upstream of the introduction pipe opening from the introduction pipe opening. Among them, the length from the upstream end of the mixing section to the introduction pipe opening is 50% or more, particularly 90% of the length from the upstream end to the downstream end of the mixing section. % Or more is preferable. By adopting such a configuration, the dilution gas does not flow directly from the dilution gas introduction pipe to the mixed gas discharge pipe, but becomes a turbulent flow after introduction into the mixed gas discharge pipe in a state where the dilution gas is entrained. Discharged. Therefore, the dilution gas can be more reliably mixed with the dilution gas by retaining the dilution gas in the mixing portion for a long time in a turbulent state and introducing the dilution gas into the turbulent flow.

  Moreover, the shape of the introduction penetration part, the penetration position, etc. are not particularly limited. For example, the introduction penetration part has a straight shape, and penetrates straight from the upstream wall surface to the downstream side of the mixing part. can do. Moreover, the introduction penetration part may be penetrated from the wall surface of the side part of the mixing part, or the wall surface of the downstream side, and may have a shape such that the introduction pipe opening part faces downstream. Furthermore, in the present invention, even if the mixed gas discharge pipe penetrates into the mixing section, the same effect as when the introduction penetrating section penetrates into the mixing section can be obtained. Both of the mixed gas discharge pipes may penetrate into the mixing part.

  As the shape of the mixing portion of a general diluting device, a columnar shape such as a cylinder is often used, but in the mixing portion of the diluting device of the present invention, the shape of the cross section perpendicular to the axis of the column shape Various shapes such as a circle, an ellipse, and a rectangle can be used. The direction of the axis of the mixing unit may be the direction of gravity, the direction perpendicular to the gravity, or the direction oblique to the gravity. Moreover, the shape of the said mixing part can use the shape from which the cross-sectional shape of the direction perpendicular | vertical to the flow of dilution gas changes with places like the dilution apparatus illustrated in FIG. Specifically, as shown in FIG. 6 (a), a cross-sectional shape in a direction parallel to the flow of the dilution gas is not rectangular, and a shape in which the wall surface of the mixing portion is bent at an obtuse angle can also be used. Furthermore, in the present invention, as shown in FIG. 6B, the cross-sectional shape in a direction parallel to the flow of the dilution gas is not a rectangle, and a shape in which the wall surface of the mixing portion is bent at an acute angle may be used. it can.

  As long as the diluting device of the present invention has a cross-sectional enlarged portion as described above, its effect can be exhibited in various shapes. For example, as shown in FIG. 2, when the cross-sectional shape of the downstream opening 8 of the cross-sectional enlarged portion 9 and the cross-sectional shape of the dilution gas introduction side surface of the mixing portion 2 are substantially the same, the cross-sectional enlarged portion 9 is A dilution gas introduction pipe 4 may be provided so as to penetrate therethrough. FIG. 7 shows an example of the cross-sectional shape perpendicular to the axis of the diluted gas introduction pipe 3 of such a dilution apparatus. In addition, as shown in FIG. 3, the dilution gas may be introduced from a side surface different from the dilution gas introduction side surface of the mixing unit 2. Furthermore, as shown in FIG. 4, the cross-sectional enlarged portion 9 and the dilution gas introduction pipe 4 may be connected to the mixing section 2 so that they are adjacent to each other. An example of the shape of a cross section perpendicular to the axis is shown in FIG.

  In the present invention, the axis of the diluted gas introduction pipe, the axis of the dilution gas introduction pipe, and the axis of the mixing unit may not be in the same direction. For example, as shown in FIG. 9A, the axis of the diluted gas introduction pipe 3 and the axis of the mixing unit 2 may be in the same direction, and the axis of the dilution gas introduction pipe may be different. Further, as shown in FIG. 9B, the axis of the diluted gas introduction pipe 3 may be inclined with respect to the axis of the mixing unit 2 and the axis of the dilution gas introduction pipe.

  The diluting device of the present invention can be used for diluting the anode off-gas discharged from the anode of the fuel cell system. At this time, the dilution gas used for diluting the fuel electrode off-gas which is the gas to be diluted is not particularly limited, and the air electrode off-gas discharged from the air electrode of the fuel cell system can also be used. Such a fuel cell system is not particularly limited, and can be used for a fuel cell system in which hydrogen is continuously discharged or a fuel cell system in which hydrogen is intermittently discharged. . In the case of a fuel cell system in which hydrogen is continuously discharged, the amount of gas discharged and the flow rate are constant, which causes water adhesion and freezing near the outlet of the diluted gas introduction pipe. Such an inconvenience can be prevented by providing the cross-sectional enlarged portion in the diluting device. On the other hand, in the case of a fuel cell system of a type in which hydrogen is intermittently discharged, the flow rate of the exhaust gas is often relatively fast because the gas is instantaneously discharged. When such a fast-flowing gas is introduced into the mixing section and the pressure drops rapidly, an air vortex is likely to be generated, and the above-described pressure loss is likely to occur. Can be effectively prevented.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

It is a schematic block diagram which shows an example of the fuel cell system with which the dilution apparatus of this invention is used. It is a schematic block diagram which shows an example of the dilution apparatus of this invention. It is a schematic block diagram which shows the other example of the dilution apparatus of this invention. It is a schematic block diagram which shows the other example of the dilution apparatus of this invention. It is a schematic block diagram which shows an example of the cross-sectional expansion part used for this invention. It is a schematic block diagram which shows the other example of the dilution apparatus of this invention. It is a schematic sectional drawing which shows an example of the dilution apparatus of this invention. It is a schematic sectional drawing which shows an example of the dilution apparatus of this invention. It is a schematic block diagram which shows the other example of the dilution apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Dilution apparatus 2 ... Mixing part 3 ... Diluted gas introduction pipe 4 ... Dilution gas introduction pipe 5 ... Mixed gas discharge pipe 6 ... Diluted gas piping part 7 ... Upstream side opening part 8 ... Downstream side opening part 9 ... Cross-sectional expansion Part 10 ... Introduction penetration part 11 ... Introduction pipe opening part

Claims (3)

A fuel exhaust gas dilution device for a fuel cell system for mixing a gas to be diluted and a dilution gas,
A mixing unit for mixing the dilution gas and the dilution gas, a dilution gas introduction pipe for introducing the dilution gas into the mixing unit, and a dilution gas introduction for introducing the dilution gas into the mixing unit A pipe, and a mixed gas discharge pipe for discharging the mixed gas in the mixing section,
The diluted gas introduction pipe has a diluted gas pipe part for introducing the diluted gas into the mixing part, and a cross-sectional enlarged part connected to the downstream side of the diluted gas pipe part,
The cross-sectional enlarged portion has an upstream opening connected to the downstream side of the dilution gas piping portion, and a downstream opening connected to the mixing portion,
The cross-sectional area of the cross-section perpendicular to the axis of the diluted gas introduction pipe of the downstream opening of the cross-sectional enlarged section is perpendicular to the axis of the diluted gas introduction pipe of the upstream opening of the cross-sectional enlarged section. A fuel exhaust gas dilution device for a fuel cell system, characterized by being larger than a cross-sectional area of the cross section. The cross-sectional area of a cross section perpendicular to the axis of the dilution gas introduction pipe of the cross-section enlarged portion continuously increases from the dilution gas piping section side to the mixing section side. 2. A fuel exhaust gas dilution device for a fuel cell system according to 1. The mixing portion is provided with an introduction penetrating portion provided at an end of the dilution gas introduction pipe,
An introduction pipe opening which is an opening is provided at an end of the introduction penetration part,
3. The fuel cell system according to claim 1, wherein a downstream opening of the dilution gas introduction pipe is provided upstream of a flow of dilution gas from the introduction pipe opening. 4. Fuel exhaust gas dilution device.

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