JP2007015872A - Hydrogen supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen supply device capable of preventing the autoignition of a combustible gas from occurring in a heating section for heating a reforming section. <P>SOLUTION: The hydrogen-fuel supply device 10 is provided with: a reforming section 46 for generating a hydrogen-containing fuel gas by reforming a raw material; a heating section 48 for providing, to the reforming section 46, the catalyst combustion heat generated by bringing the combustible and combustion-supporting gases into contact with a catalyst to keep a reforming reaction; and a mixer 60 for mixing the combustible and combustion-supporting gases prior to their introduction into the heating section 48. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrogen supply device for supplying hydrogen to a hydrogen consuming device such as a fuel cell.

For example, as a hydrogen supply device for obtaining hydrogen to be supplied to a fuel cell, a reforming type hydrogen supply device that reforms a hydrocarbon raw material into a hydrogen-containing gas by a reforming reaction including steam reforming is considered. (For example, refer to Patent Document 1). In such a hydrogen supply apparatus, in order to maintain a reforming reaction that is an endothermic reaction, a reforming unit that performs the reforming reaction and a combustion unit that applies heat to the reforming unit are provided adjacent to each other, and the reforming reaction is performed. It can be performed continuously. And, it is considered that the anode off gas of the fuel cell is used as the fuel of the combustion section. Since the anode off gas is supplied to the combustion section at a relatively high temperature close to the operating temperature of the fuel cell, there is an advantage that there is little sensible heat loss due to the temperature rise of the combustion gas.
JP-A-2001-283890

  By the way, when adopting a configuration in which the anode off gas is catalytically combusted in the combustion section for heating the reforming section, the anode off gas supplied at a relatively high temperature as described above is self-contacted with the combustion air (combustion gas). There is a concern that gas phase combustion may occur in the combustion section after ignition. This gas phase combustion propagates to the anode off gas supply side (so-called backfire occurs), so that the heat generated by the combustion is not consumed in the reforming section, and the combustion temperature is higher than in the case of performing catalytic combustion. Become. For this reason, the self-ignition of the anode off-gas that causes gas phase combustion causes damage to components such as the combustion section and promotes deterioration of the constituent materials.

  In view of the above fact, an object of the present invention is to obtain a hydrogen supply device that can prevent the self-ignition of a combustible gas in a heating unit for heating the reforming unit.

  In order to achieve the above object, a hydrogen supply apparatus according to claim 1 includes a reforming unit that performs a reforming step for generating a fuel gas containing hydrogen from a supplied raw material, and a supplied combustible gas. A heating unit for bringing catalytic combustion gas into contact with the catalyst to cause catalytic combustion, and supplying heat generated by the catalytic combustion to the reforming unit as heat for performing the reforming step; and the combustible gas And a combustion support gas are mixed before being supplied to the heating unit.

  In the hydrogen supply device according to the first aspect, the reforming unit receives the supply of heat from the heating unit, maintains the reforming process, and generates a fuel gas containing hydrogen. The combustible gas and the combustion supporting gas are mixed in a mixer and supplied to the heating unit as a mixed gas. For this reason, the combustible gas and the combustion support gas can shorten the mixing time, that is, the gas phase residence time for contacting in the gas phase for mixing before the contact with the catalyst, as compared with the configuration without the mixer. . Thereby, in this hydrogen supply apparatus, generation | occurrence | production of the gaseous-phase combustion by the self-ignition of combustible gas is prevented or suppressed effectively. In addition, even if gas phase combustion occurs, the combustible gas and the supporting gas are mixed almost uniformly by the mixer, so that a portion where the combustible gas or the supporting gas has a locally high concentration is generated. Is prevented and the combustion temperature is suppressed.

  Thus, in the hydrogen supply device according to the first aspect, it is possible to prevent the self-ignition of the combustible gas from occurring in the heating unit for heating the reforming unit. For this reason, in this hydrogen supply device, at least one of the combustible gas and the combustion supporting gas is introduced into the heating unit (mixer) at a temperature at which self-ignition of the combustible gas can occur, and the sensible heat loss in the heating unit is small. It is possible to realize a configuration with high thermal efficiency.

  A hydrogen supply apparatus according to a second aspect of the present invention is a hydrogen supply apparatus for supplying a hydrogen-containing fuel gas to a hydrogen consuming apparatus that operates at a predetermined operating temperature, wherein the fuel contains hydrogen from the supplied raw material. A reforming section for performing a reforming step for generating a gas; and the supplied combustible gas and supporting gas are brought into contact with a catalyst to cause catalytic combustion, and heat generated by the catalytic combustion is supplied to the reforming section. A heating section for supplying heat for performing the reforming step, a combustible gas introduction path for introducing a component of the fuel gas that is not consumed by the hydrogen consuming device into the heating section as the combustible gas, and the combustible gas introduction path. And a mixer for mixing the combustible gas and the combustion support gas.

  According to a second aspect of the present invention, the reforming unit receives heat supplied from the heating unit, maintains the reforming process, and generates a fuel gas containing hydrogen. This fuel gas is supplied to a hydrogen consuming device, and mainly hydrogen is consumed, and the remaining components including the combustible gas of this fuel gas are introduced into the mixer as a combustible gas at a substantially predetermined operating temperature. The combustible gas is mixed with the combustion support gas in a mixer and supplied to the heating unit as a mixed gas. For this reason, the combustible gas and the combustion support gas can shorten the mixing time, that is, the gas phase residence time for contacting in the gas phase for mixing before the contact with the catalyst, as compared with the configuration without the mixer. . Thereby, in this hydrogen supply apparatus, generation | occurrence | production of the gaseous-phase combustion by the self-ignition of combustible gas is prevented or suppressed effectively. In addition, even if gas phase combustion occurs, the combustible gas and the supporting gas are mixed almost uniformly by the mixer, so that a portion where the combustible gas or the supporting gas has a locally high concentration is generated. Is prevented and the combustion temperature is suppressed.

  Thus, in the hydrogen supply device according to the second aspect, it is possible to prevent the self-ignition of the combustible gas from occurring in the heating section for heating the reforming section. For this reason, in this hydrogen supply device, it is possible to introduce a combustible gas into the heating unit (mixer) at the operating temperature of the hydrogen consuming device, and realize a highly efficient configuration with little sensible heat loss in the heating unit. is there. In addition, the temperature range of the fuel gas generated in the reforming unit is configured to be substantially the same as the operating temperature range of the hydrogen consuming apparatus, and the system including the hydrogen consuming apparatus has high thermal efficiency. It is also possible to realize the configuration.

  A hydrogen supply device according to a third aspect of the invention is a hydrogen supply device for supplying a hydrogen-containing fuel gas to a hydrogen consuming device that operates at a predetermined operating temperature, wherein the fuel contains hydrogen from the supplied raw material. A reforming section for performing a reforming step for generating a gas; and the supplied combustible gas and supporting gas are brought into contact with a catalyst to cause catalytic combustion, and heat generated by the catalytic combustion is supplied to the reforming section. A heating unit that supplies heat for performing the reforming step, and an oxygen-containing refrigerant after cooling the hydrogen consuming device to operate the hydrogen consuming device at the predetermined operating temperature is used as the combustion support gas. A combustion support gas introduction path to be introduced into the heating unit; and a mixer that is provided in the combustion support gas introduction path and mixes the combustible gas and the combustion support gas.

  According to a third aspect of the present invention, the reforming unit receives heat supplied from the heating unit, maintains the reforming process, and generates a fuel gas containing hydrogen. This fuel gas is supplied to the hydrogen consuming apparatus, and mainly hydrogen is consumed. At this time, the hydrogen consuming apparatus is cooled by an oxygen-containing refrigerant (for example, air), and the operating temperature is maintained at a predetermined operating temperature (a certain range). The refrigerant (off-gas) after cooling the hydrogen consuming device is introduced into the mixer as a combustion-supporting gas at a substantially predetermined operating temperature.

  This combustion support gas is mixed with combustible gas by a mixer and supplied to the heating unit as a mixed gas. For this reason, the combustible gas and the combustion support gas can shorten the mixing time, that is, the gas phase residence time for contacting in the gas phase for mixing before the contact with the catalyst, as compared with the configuration without the mixer. . Thereby, in this hydrogen supply apparatus, generation | occurrence | production of the gaseous-phase combustion by the self-ignition of combustible gas is prevented or suppressed effectively. In addition, even if gas phase combustion occurs, the combustible gas and the supporting gas are mixed almost uniformly by the mixer, so that a portion where the combustible gas or the supporting gas has a locally high concentration is generated. Is prevented and the combustion temperature is suppressed.

  Thus, in the hydrogen supply device according to the third aspect, it is possible to prevent the self-ignition of the combustible gas from occurring in the heating unit for heating the reforming unit. For this reason, in this hydrogen supply device, it is possible to introduce a combustion-supporting gas into the heating unit (mixer) at the operating temperature of the hydrogen consuming device, and realize a highly efficient configuration with little sensible heat loss in the heating unit. It is. In addition, the temperature range of the fuel gas generated in the reforming unit is configured to be substantially the same as the operating temperature range of the hydrogen consuming apparatus, and the system including the hydrogen consuming apparatus has high thermal efficiency. It is also possible to realize the configuration.

  A hydrogen supply apparatus according to a fourth aspect of the present invention is the hydrogen supply apparatus according to the third aspect, wherein a component of the fuel gas that is not consumed by the hydrogen consuming apparatus is introduced into the heating section as the flammable gas. A mixer is further provided, and the mixer is disposed at a junction of the combustible gas introduction path and the combustion support gas introduction path.

  5. The hydrogen supply apparatus according to claim 4, wherein the fuel gas (remaining components including the combustible gas) generated in the reforming unit and mainly consumed by the hydrogen consuming apparatus is combustible gas at a substantially predetermined operating temperature. As introduced into the mixer. The combustible gas is mixed with the combustion support gas in a mixer and supplied to the heating unit as a mixed gas. For this reason, in a mixer, the combustible gas and combustion support gas of the substantially same temperature (operating temperature of a hydrogen consumption apparatus) are mixed. That is, in this configuration, the temperature of the mixed gas is in the same region as the operating temperature of the hydrogen consuming device, and the heat efficiency is improved by setting the reformer so that fuel gas having a temperature in the same region as the operating temperature is generated. A higher configuration can be realized. On the other hand, since the combustible gas is not cooled by the combustion support gas, self-ignition of the combustible gas is likely to occur, but as described above, the gas phase residence time of the mixed gas is shortened by the mixer. Generation | occurrence | production of the gaseous-phase combustion by the self-ignition of combustible gas can be prevented or suppressed effectively.

  A hydrogen supply apparatus according to a fifth aspect of the present invention is the hydrogen supply apparatus according to the fourth aspect, wherein the operating temperature of the hydrogen consuming apparatus is in the range of 300 ° C to 600 ° C.

  In the hydrogen supply device according to claim 5, since the operating temperature range of the hydrogen consuming device is in the middle temperature range of 300 ° C. to 600 ° C., the reforming unit generates fuel gas in the middle temperature range of 300 ° C. to 600 ° C. If it is supplied to the hydrogen consuming apparatus, the efficiency is good. Thus, if it comprises so that fuel gas temperature may become the same range as the operating temperature of a hydrogen consumption apparatus, the thermal efficiency of the system comprised including a hydrogen supply apparatus and a hydrogen consumption apparatus will become high. In such a configuration, the temperature of the mixed gas introduced into the mixer is 300 ° C. to 600 ° C., and is a temperature range in which self-ignition can occur depending on the composition of the combustible gas. By adopting a configuration in which the gas phase residence time is shortened, the occurrence of gas phase combustion due to self-ignition of the combustible gas is prevented or effectively suppressed. In addition, as a hydrogen consumption apparatus which operate | moves in the middle temperature range of 300 to 600 degreeC, the type of fuel cell etc. which operate | move in a middle temperature range can be raised, for example. Moreover, the operating temperature range of the hydrogen consuming apparatus can be set to a range of about 400 ° C. to 500 ° C., which is a more stable range.

  A hydrogen supply apparatus according to a sixth aspect of the present invention is the hydrogen supply apparatus according to any one of the first to fifth aspects, wherein the mixer independently includes a plurality of the combustible gas and the combustion support gas. A gas flow splitting part that divides the gas flow splitting part, and the combustible gas and the combustion supporting gas that are arranged between the gas flow splitting part and the gas flow splitting part that are arranged between the gas flow splitting part and the heating part. And a mixing unit for mixing the two.

  In the hydrogen supply device according to claim 6, the combustible gas and the combustion supporting gas divided into the plurality of flow paths independently of each other (in a non-contact manner) in the gas flow dividing section are diffused in the mixing section for a short time. To mix evenly. Thereby, compared with the structure which is not provided with a gas flow division | segmentation part, the spatial distance required for mixing in a mixing part, ie, the gaseous phase residence time of combustible gas, can be shortened significantly. Moreover, since each gas flow is divided | segmented into each plurality, the density | concentration of mixed gas is made more uniform. Therefore, in this hydrogen supply apparatus, generation | occurrence | production of the gaseous-phase combustion by self-ignition of combustible gas is prevented or suppressed more effectively.

  A hydrogen supply apparatus according to a seventh aspect of the present invention is the hydrogen supply apparatus according to the sixth aspect, wherein the gas flow dividing section includes a plurality of flat combustible gas dividing flow paths through which the combustible gas passes, respectively. A plurality of flat combustion gas dividing flow paths through which the combustion supporting gas passes are alternately stacked in the short direction of each divided flow path.

  In the hydrogen supply device according to claim 7, the combustible gas ejected from the flat combustible gas dividing flow path to the mixing portion diffuses in the gas flow direction of the combustible gas divided flow path, and is adjacent to the end direction. The combustion gas dividing flow path ejected from the fuel gas dividing flow path to the mixing portion is mixed evenly (effectively) in a shorter time. That is, the combustible gas and the combustion supporting gas that have passed through the flat channel are each subjected to a high shear force and diffuse in the gas flow direction (the flow is turbulent), and the mixing is promoted. In addition, since the combustible gas and the combustion support gas before mixing are divided into minute flow rates and mixed by passing through a plurality of flat channels, the local high concentration portion of the combustible gas or combustion support gas is reduced. Formation is effectively prevented. In addition, as such a gas flow division | segmentation part, it can comprise using the microchannel etc. which have many fine flow paths, for example.

  As described above, the hydrogen supply device according to the present invention has an excellent effect that it is possible to prevent the self-ignition of the combustible gas from occurring in the heating section for heating the reforming section.

  A hydrogen supply apparatus 10 according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a system configuration diagram (process flow sheet) of a fuel cell system 12 to which a hydrogen supply device 10 is applied. As shown in this figure, the hydrogen supply device 10 supplies a fuel gas containing hydrogen to the fuel cell 14.

  The fuel cell 14 includes an anode channel 16 for introducing a fuel gas containing hydrogen into the anode electrode, and a cathode channel 18 for introducing cathode air containing oxygen as an oxidizing gas into the cathode electrode. The electromotive force is generated by the electrochemical reaction between hydrogen supplied to the anode electrode and oxygen supplied to the cathode electrode. Specifically, the fuel cell 14 has a stack in which the single cells 20 shown in FIG. 5 are stacked. The unit cell 20 is configured by sandwiching an electrolyte layer 22 from both sides by a pair of separators 24 and 26. Each separator 24, 26 is made of a conductive and gas-impermeable material (for example, carbon). One separator 24 is open to the electrolyte layer 22 side to form the cathode flow path 18, and the other separator 24 is open to the electrolyte layer 22 side to form the anode flow path 16.

The electrolyte layer 22 includes an electrolyte membrane 22A that is a solid oxide, a cathode 22B that is disposed on the separator 24 side of the electrolyte membrane 22A, and an anode 22C that is disposed on the separator 26 side of the electrolyte membrane 22A. The electrolyte membrane 22A, for example BaCeO ₃ system can be a perovskite electrolyte membrane ₃ system, etc. SrCeO. Further, as the cathode 22B (cathode catalyst), for example, one having a platinum (Pt) -based diffusion layer is used.

  The anode 22C is configured by laminating a hydrogen molecule dissociation layer 28 on the separator 26 side and a hydrogen separation membrane 30 on the electrolyte membrane 22A side. As the hydrogen molecule dissociation layer 28, for example, a palladium thin film is used, and this palladium thin film also functions as a catalyst for the anode electrode. Note that a platinum-based catalyst may be employed as a catalyst for the anode electrode as necessary. For the hydrogen separation membrane 30, for example, a metal having selective hydrogen permeability such as a vanadium membrane is used. It is also possible to grasp the laminated film of the hydrogen molecule dissociation layer 28 and the hydrogen separation membrane 30 as a hydrogen separation membrane.

  In the fuel cell 14 (single cell 20) described above, hydrogen in the fuel gas introduced into the anode channel 16 is protonated in the anode 22C (hydrogen molecule dissociation layer 28), and this proton permeates the hydrogen separation membrane 30. Then, it reaches the electrolyte membrane 22A and further moves to the cathode 22B. In this cathode 22B, this proton and oxygen introduced into the cathode channel 18 react to generate water (water vapor). Along with this movement of protons, electrons flow from the anode 22C (separator 26) to the cathode (separator 24) through the external conductor to generate power.

  Thus, the fuel cell 14 is configured to generate power by supplying the hydrogen-containing fuel gas to the anode channel 16 and supplying cathode air to the cathode channel 18. In other words, the fuel cell system 12 can generate power by supplying a mixed gas of hydrogen and another gas to the anode flow path without separating only hydrogen from the fuel gas before being supplied to the fuel cell 14. It is configured.

  The fuel cell 14 provided with the hydrogen separation membrane 30 is diffused when the hydrogen separation membrane 30 becomes high temperature, and may deteriorate due to hydrogen embrittlement when the low temperature hydrogen separation membrane 30 comes into contact with hydrogen. Is maintained within a predetermined temperature range (for example, 200 ° C to 700 ° C, preferably 300 ° C to 600 ° C, more preferably 400 ° C to 500 ° C). Specifically, in the fuel cell system 12, as schematically shown in FIG. 1, a refrigerant flow path 32 is provided in the fuel cell 14 (between the single cells 20), and the refrigerant that passes through the refrigerant flow path 32. In this embodiment, the operation temperature of the fuel cell 14 is maintained within the predetermined temperature range described above by air.

  The fuel cell system 12 includes a cathode air pump 34 for supplying cathode air as an oxygen-containing gas to the cathode flow path 18 of the fuel cell 14. The discharge part of the cathode air pump 34 is connected to the upstream end of the cathode air supply line 36 whose downstream end is connected to the cathode air inlet 18 </ b> A of the cathode channel 18. On the other hand, the upstream end of the cathode offgas line 38 is connected to the cathode offgas outlet 18B of the cathode channel 18. In this embodiment, since the cathode offgas containing water vapor and oxygen (air) is used as a reforming gas in the reformer 45 (described later) of the hydrogen supply device 10, the downstream end of the cathode offgas line 38 is located at the hydrogen supply device. 10 has been introduced. This configuration will be described later.

  Further, the fuel cell system 12 includes a cooling air pump 40 for supplying cooling air as a refrigerant to the refrigerant flow path 32 of the fuel cell 14. The discharge part of the cooling air pump 40 is connected to the upstream end of the refrigerant line 42 whose downstream end is connected to the refrigerant inlet 32 </ b> A of the refrigerant flow path 32. On the other hand, the upstream end of the cooling off gas line 44 is connected to the refrigerant outlet 32 </ b> B of the refrigerant flow path 32. In this embodiment, the downstream end of the cooling off-gas line 44 is introduced into the hydrogen supply device 10 in order to use the cooling off-gas containing oxygen as a combustion support gas in the reformer 45 of the hydrogen supply device 10. This configuration will be described later.

  The hydrogen supply device 10 is a reforming hydrogen supply source that reforms a hydrocarbon raw material to obtain a fuel gas containing hydrogen. Therefore, the hydrogen supply apparatus 10 includes a reformer 45 for performing a reforming reaction. The reformer 45 includes a reforming unit 46 that performs a reforming reaction and a reforming unit 46 that is used for reforming. And a heating unit 48 for applying heat. This will be specifically described below.

The reforming unit 46 generates a fuel gas containing hydrogen gas by performing a catalytic reaction between the supplied hydrocarbon gas (gasoline, methanol, natural gas, etc.) and the reforming gas (steam, oxygen) (reformation). Reaction). The reforming reaction includes reactions represented by the following formulas (1) to (4). Therefore, the fuel gas obtained in the reforming process includes hydrogen (H ₂ ), carbon monoxide (CO), methane (CH ₄ ), cracked hydrocarbons, unreacted raw material hydrocarbons (C _x H _y ), etc. Combustible gas and nonflammable gases such as carbon dioxide (CO ₂ ) and water (H ₂ O) are included.

_{C n H m + nH 2 O} → nCO + (n + m / 2) H 2 ... (1)
_{C n H m + n / 2O} 2 → nCO + m / 2H 2 ... (2)
CO + H ₂ O⇔CO ₂ + H ₂ (3)
CO + 3H ₂ ＣＨ CH ₄ + H ₂ O (4)
This reforming reaction is an endothermic reaction, and is performed at a predetermined temperature or higher (in the present embodiment, about 700 ° C. to 800 ° C.), so that the reforming reaction is performed at 400 ° C. A fuel gas of 500 ° C. is generated. For this reason, the reformer 45 has a heating unit 48 that supplies heat that can perform a reforming reaction to the reforming unit 46 to maintain the reforming reaction. The heating section 48 has an oxidation catalyst 49 (see FIG. 4) inside and is provided adjacent to the reforming section 46, and reforms the heat obtained by catalytic combustion of the fuel through the partition wall section 50. It supplies to the part 46. FIG. For this reason, the structure which can provide heat quantity directly to the reforming part 46, without converting calorie | heat amount into temperature like the structure which heats a reforming part via heating media (fluid), such as combustion gas It is said that. In this embodiment, the reformer 45 is configured as a heat exchanger of a type in which the reforming section 46 and the heating section 48 are alternately stacked via the partition 50 as shown in FIG. . As shown in FIG. 4, the oxidation catalyst 49 is fixedly supported on the inner surface of the heating unit 48, that is, the partition wall 50.

  The hydrogen supply apparatus 10 includes a raw material pump 52 for supplying a hydrocarbon raw material stored in a fuel tank (not shown) to the reforming unit 46 of the reformer 45, and a discharge part of the raw material pump 52 is a raw material. The feed line 54 is connected to the raw material inlet 46 </ b> A of the reforming unit 46. Further, the downstream end of the cathode offgas line 38 is joined to the raw material supply line 54. Thus, the reforming unit 46 is configured to be supplied with both the hydrocarbon raw material and the cathode offgas (water vapor and oxygen) as the reforming gas from the raw material inlet 46A. Note that a mixer, an injector, or the like may be provided at the junction between the raw material supply line 54 and the cathode offgas line 38 to promote mixing of the hydrocarbon raw material and the reforming gas.

Further, the fuel gas outlet 46B of the reforming unit 46 is connected to the upstream end of the fuel gas supply line 56 whose downstream end is connected to the fuel gas inlet 16A of the fuel cell 14. As a result, the hydrogen-containing fuel gas generated by reacting the hydrocarbon raw material with the cathode off-gas in the reforming unit 46 is supplied to the anode flow path 16 of the fuel cell 14. On the other hand, the fuel cell 14 having the hydrogen separation membrane 30 as described above consumes only hydrogen in the fuel gas to generate power. For this reason, the anode off-gas contains a combustible gas such as carbon monoxide (CO) or hydrocarbon (C _x H _y ), and the hydrogen supply device 10 (the reformer 45) is connected to the fuel cell 14. The anode off gas is used as fuel for the heating unit 48. In other words, the anode off-gas line 58 whose upstream end is connected to the anode off-gas outlet 16B of the anode channel 16 has its downstream end introduced into the hydrogen supply device 10.

  Therefore, in the hydrogen supply device 10, that is, the reformer 45, the anode off-gas that is a combustible gas is catalytically combusted in the heating unit 48 using the cooling off-gas (oxygen therein) as a combustion-supporting gas, It is set as the structure which secures the heat which maintains. The anode off gas and the cooling off gas are respectively supplied at a temperature (about 400 ° C. to 500 ° C.) corresponding to the operating temperature of the fuel cell 14 and cause catalytic combustion in a temperature range of about 600 ° C. to 800 ° C. . In response to the supply of heat from the heating unit 48, the reforming unit 46 generates fuel gas having a temperature substantially the same as the operating temperature range of the fuel cell 14 as described above, and supplies the fuel gas to the fuel cell 14. It has become. Thereby, in the fuel cell system 12, the structure with high thermal efficiency is implement | achieved without providing a heat exchanger etc. Depending on the operating conditions (to control the amount of heat generated), part of the cathode off-gas and cooling off-gas is discharged out of the system (the supply amount to the reforming unit 46 and heating unit 48 is adjusted). It may be configured.

  And the hydrogen supply apparatus 10 which concerns on embodiment of this invention is equipped with the mixer 60 for mixing before supplying anode offgas and cooling offgas to the heating part 48. FIG. That is, the mixer 60 has the combustible gas inlet 60A connected to the downstream end of the anode offgas line 58 and the combustible gas inlet 60B connected to the downstream end of the cooling offgas line 44. Further, the mixed gas outlet 60 </ b> C of the mixer 60 is connected to the mixed gas inlet 48 </ b> A of the heating unit 48. As a result, the heating unit 48 is supplied with a mixed gas in which the anode off gas and the cooling off gas are substantially uniformly mixed from the mixer 60. The combustion exhaust gas outlet 48 </ b> B of the heating unit 48 is connected to the exhaust unit 64 via the exhaust gas line 62. The exhaust part 64 is configured to purify the combustion exhaust gas and make it outside the system (in the atmosphere).

  Hereinafter, the mixer 60 will be described in detail. As shown in FIG. 2, the mixer 60 includes a combustible gas introduction pipe portion 66 provided with a combustible gas inlet 60A, a support gas introduction pipe portion 68 provided with a support gas inlet 60B, and a mixed gas outlet 60C. Is provided with a mixer main body 72 configured to communicate with a mixed gas lead-out pipe portion 70 provided with a three-pronged shape. The mixer main body 72 has a combustible gas introduction pipe section 66, a combustion support gas introduction pipe section 68, and a mixed gas outlet pipe section 70 each having a rectangular frame shape (substantially square frame shape in this embodiment). ing.

  A gas flow dividing section 74 is provided in the mixer main body 72 from the junction of the combustible gas introduction pipe section 66 and the support gas introduction pipe section 68 to a part of the mixed gas outlet pipe section 70. . The gas flow dividing unit 74 divides the anode off-gas introduced via the combustible gas introduction pipe part 66 into a large number of minute flows, and also produces a large number of cooling off-gas introduced via the combustion support gas introduction pipe part 68. It is designed to be divided into minute streams. Further, the downstream portion of the gas flow dividing section 74 in the mixed gas outlet pipe section 70 is a mixing space 76 for mixing and mixing the anode off-gas and the cooling off-gas divided into a large number of minute streams. .

  As shown in FIG. 3, the gas flow dividing section 74 is configured by alternately stacking a plurality of combustible gas flow dividing plates 78 and supporting gas flow dividing plates 80 each formed in a substantially pentagonal plate shape. . From the combustible gas flow dividing plate 78, a plurality of standing walls 78 </ b> A that are elongated in a direction intersecting the gas flow direction of the support gas introducing pipe portion 68 and a plurality of standing walls along the tube wall of the mixed gas outlet pipe portion 70. 78B is erected. Further, from the combustion support gas flow dividing plate 80, a plurality of standing walls 80 </ b> A elongated in a direction intersecting with the gas flow direction of the combustible gas introduction pipe portion 66 and a plurality along the tube wall of the mixed gas outlet pipe portion 70. The standing wall 80B is erected.

  Each standing wall 78A, 78B of the combustible gas flow dividing plate 78 is in contact with a surface of the supporting gas flow dividing plate 80 on the side opposite to the standing wall 80A, 80B, and a slit-like combustible gas dividing flow path 78C (see FIG. 4), and the standing wall 78A located closest to the combustion supporting gas introduction pipe portion 68 among the plurality of standing walls 78A prevents the mixing of the cooling off gas into the combustible gas dividing flow path 78C. Yes. Each of the standing walls 78A and 78B further divides the combustible gas dividing flow path 78C formed between the combustible gas flow dividing plate 78 and the support gas flow dividing plate 80 (also in a direction perpendicular to the stacking direction). It is like that.

  Similarly, each of the standing walls 80A and 80B of the combustion support gas flow dividing plate 80 abuts against the surface of the combustible gas flow split plate 78 on the side opposite to the standing wall 78A and 78B, so that the split support gas split flow in the form of a slit. The standing wall 80A that forms the path 80C (see FIG. 4) and is located closest to the combustible gas introduction pipe portion 66 among the plurality of standing walls 80A prevents the anode off gas from being mixed into the combustion support gas dividing flow path 80C. It is like that. Further, each of the standing walls 80A and 80B is configured to further divide the support gas dividing flow path 80C formed between the support gas flow dividing plate 80 and the combustible gas flow dividing plate 78.

  That is, each of the standing walls 78A, 78B, 80A, 80B is configured to perform a function as a spacer and a function as a partition plate. In this embodiment, the protruding height of each standing wall 78A, 78B, 80A, 80B, that is, the short dimension of the combustible gas dividing channel 78C and the supporting gas dividing channel 80C is approximately 200 to 700 μm (for example, 500 μm), The interval between the standing walls 78A, 78B, 80A, 80B is approximately 2 to 5 mm. Therefore, the gas flow dividing section 74 is a so-called micro-type in which flat combustible gas dividing flow paths 78C and combustion supporting gas dividing flow paths 80C are stacked in the short direction (in this embodiment, alternately stacked for each gas type). It is a channel structure.

  As shown in FIG. 4, the mixed gas outlet pipe portion 70, that is, the mixed gas outlet 60 </ b> C that is the most downstream portion of the mixing space 76, is a mixed gas inlet of a plurality of heating units 48 that are alternately stacked with a plurality of reforming units 46. 48A communicates directly with each other. That is, the mixing space 76 also functions as a mixed gas inlet header of each heating unit 48. Thereby, compared with the structure which connects 48 A of mixed gas inlet ports and 60 C of mixed gas outlets by piping etc., it is set as the structure where the distance from the exit of the gas flow division | segmentation part 74 to the inlet of each heating part 48 is short.

  The performance of the mixer 60 described above will be described with reference to FIGS. In the following description, the stacking direction of each combustible gas flow dividing plate 78 and the supporting gas flow dividing plate 80 is defined as the Y direction and the direction perpendicular to the Y direction when the gas flow dividing portion 74 is viewed from the mixing space 76 side. X direction.

  FIG. 6A is a diagram showing the flow velocity distribution of the gas ejected from the respective portions in the Y direction at the central portion in the X direction of the gas flow dividing portion 74 to the mixing space 76. Here, five points that divide the gas flow dividing portion 74 into approximately six equal parts in the Y direction were used as flow velocity measurement points. Further, the flow velocity sensor was disposed at a position 3 mm from the downstream end of the gas flow dividing portion 74 in each part of the gas flow dividing portion 74 in the Y direction. In this experiment, room temperature helium gas was used in place of the hydrogen-containing anode off-gas. On the other hand, FIG. 6B is a diagram showing the distribution of the helium gas concentration in the mixed gas of helium and air (at room temperature) at the same position in the X direction and the Y direction of the flow velocity measurement point of FIG. is there. The gas sensor was arranged at a position 0.5 mm from the downstream end of the gas flow dividing portion 74 in each part in the Y direction.

  6A and 6B, the black circle plots indicate that the average flow velocity of the mixed gas of helium and air is the flow velocity V1, and the average helium concentration (macro concentration) is the concentration D1. The experimental result when set in this way is shown. The black triangle plot shows the experimental results when the average flow velocity of the mixed gas of helium and air is set to the flow velocity V2 and the average helium concentration is the concentration D2. Further, the white circle plot shows the experimental results when the average flow velocity of the mixed gas of helium and air is set to the flow velocity V3 and the average helium concentration is the concentration D1. Furthermore, the white triangle plot shows the experimental results when the average flow velocity of the mixed gas of helium and air is set to the flow velocity V4 and the average helium concentration is the target concentration D2.

  In the mixer 60, it can be seen that, in any of the above four conditions (settings), both the flow velocity and the helium gas concentration are substantially constant in each part in the Y direction. That is, in the mixer 60, each flow of helium gas (anode off gas) and air is divided substantially uniformly into each part in the Y direction, and helium gas is directly downstream (0.5 mm point) of the gas flow dividing part 74. It was confirmed that the air and the air were mixed evenly according to the target.

  FIG. 7A is a diagram showing the flow velocity distribution of the gas ejected from the respective portions in the X direction at the central portion in the Y direction of the gas flow dividing portion 74 to the mixing space 76. Here, five points that divide the gas flow dividing section 74 into approximately six equal parts in the X direction were used as flow velocity measurement points. The flow velocity sensor was disposed at a position 3 mm from the downstream end of the gas flow dividing portion 74 in each part in the X direction. In this experiment, room temperature helium gas was used in place of the hydrogen-containing anode off-gas. On the other hand, FIG. 7B is a diagram showing the distribution of the helium gas concentration in the mixed gas of helium and air at the same position in the X direction and the Y direction of the flow velocity measurement point in FIG. The gas sensor was arranged at a position 0.5 mm from the downstream end of the gas flow dividing portion 74 in each part in the X direction. The experimental conditions (settings) for each plot in FIGS. 7A and 7B are the same as the experimental conditions for the same plot in FIG.

  In the mixer 60, it can be seen that in any of the above four conditions (settings), both the flow velocity and the helium gas concentration are substantially constant in each part in the X direction. That is, in the mixer 60, each flow of helium gas (anode off gas) and air is divided substantially uniformly into each part in the X direction, and helium gas is directly downstream of the gas flow dividing part 74 (0.5 mm point). It was confirmed that the air and the air were mixed evenly according to the target.

  As described above, the mixer 60 realizes a configuration in which a substantially uniform gas flow division effect and a uniform gas mixing effect associated therewith are obtained in each part in the X direction and the Y direction. Therefore, in the mixer 60, the anode off-gas and the cooling off-gas at 400 ° C. to 500 ° C. can be mixed almost uniformly. In this embodiment, the heating unit 48 is set to have an excess air ratio of 2 to 4, and a larger amount of cooling off gas than the anode off gas is introduced into the mixer 60. The above-described concentrations D1 and D2 are set as concentrations at which the excess air ratio is approximately 2 and 4 when the anode off gas is assumed to be pure hydrogen.

  In addition, as shown in FIG. 1, the hydrogen supply device 10 includes an exhaust return line 82 that communicates the exhaust line 62 and the cooling off-gas line 44. An ejector (jet pump) 92 serving as a dilution gas driving device is disposed at a joining portion of the exhaust return line 82 in the cooling off gas line 44. The ejector 92 introduces combustion exhaust gas from the exhaust return line 82 to the cooling off gas line 44 due to the negative pressure generated as the cooling off gas flows through the cooling off gas line 44.

  The exhaust return line 82 includes a valve 84 that can open and close the exhaust return line 82 and a check valve that prevents gas flow from the cooling off gas line 44 to the exhaust line 62 on the cooling off gas line 44 side of the valve 84. 86. The valve 84 is an adjustment valve that can change the valve opening, and the valve opening is changed (adjusted) based on a command from an electrically connected control device 88. Therefore, in the hydrogen supply device 10, when the valve 84 (exhaust return line 82) is opened, the amount of combustion exhaust gas corresponding to the amount of combustion in the heating unit 48 and the valve opening of the valve 84 is cooled by the action of the ejector 92. The gas is circulated to the off gas line 44. Instead of providing the ejector 92, for example, a gas pump (compressor) or the like that is operated when the valve 84 is opened may be provided in the exhaust return line 86.

  A temperature sensor 90 as a detector is electrically connected to the control device 88, and an output signal of the temperature sensor 90 is input. The temperature sensor 90 is disposed in the vicinity of the mixed gas inlet 48A of the heating unit 48, and is configured to output a signal corresponding to the mixed gas temperature in the vicinity of the mixed gas inlet 48A. As will be described later, when the output signal of the temperature sensor 90 exceeds a predetermined threshold value, that is, when a signal corresponding to the mixed gas temperature near the mixed gas inlet 48A exceeding the set temperature is input, the control device 88 The valve 84 is controlled.

  By the way, in the heating part 48, when the temperature immediately before the mixed gas comes into contact with the oxidation catalyst 49 is equal to or higher than the self-ignition temperature of the combustible gas (the combustible component in the anode off gas), the combustible gas may be self-ignited. In the region above the self-ignition temperature, it is known that the higher the temperature, the easier the self-ignition of the combustible gas occurs. Therefore, a signal larger than the output signal corresponding to the above-mentioned self-ignition temperature of the temperature sensor 90 (a signal exceeding the threshold value) is used as the detection signal in the present invention.

  Next, the operation of the first embodiment will be described.

  In the fuel cell system 12 including the hydrogen supply device 10 having the above-described configuration, the hydrogen generated by the reforming reaction performed by the reforming unit 46 while receiving the heat supply from the heating unit 48 in the reformer 45 of the hydrogen supply device 10. The contained fuel gas is supplied to the anode flow path 16 of the fuel cell 14 through the fuel gas supply line 56. Cathode air from the cathode air pump 34 is constantly supplied to the cathode flow path 18 of the fuel cell 14 through the cathode air supply line 36. In the fuel cell 14, hydrogen in the fuel gas introduced into the anode flow path 16 is protonated at the anode 22C (hydrogen molecule dissociation layer 28), and the protons pass through the hydrogen separation membrane 30 to the electrolyte membrane 22A. Then, it further moves to the cathode 22B. Along with this movement of protons, electrons flow from the anode 22C (separator 26) to the cathode (separator 24) through the external conductor to generate power. At the cathode 22B, protons react with oxygen introduced into the cathode channel 18 to generate water (water vapor). Further, at this time, the fuel cell 14 is cooled by the cooling air of the cooling air pump 40 supplied through the refrigerant line 42, the temperature rise due to power generation (exothermic reaction) is prevented, and the operation temperature is maintained in a certain range. Is done.

  Then, the cathode offgas containing water vapor generated at the cathode 22B as described above is joined to the raw material supply line 54 via the cathode offgas line 38, and together with the hydrocarbon raw material from the raw material pump 52, as a reforming gas, the reforming section. 46. In the reforming unit 46, the reforming reaction including the reactions of the above formulas (1) to (4) is performed by bringing the hydrocarbon raw material and the cathode offgas (hydrogen and oxygen thereof) into contact with the reforming catalyst. A fuel gas containing carbon monoxide or the like is generated, and this fuel gas is supplied to the fuel cell 14 as described above.

  The anode off gas of the fuel cell 14 is introduced into the combustible gas introduction pipe portion 66 of the mixer 60 through the anode off gas line 58, and the cooling off gas of the fuel cell 14 is introduced into the combustion support gas of the mixer 60 through the cooling off gas line 44. It is introduced into the pipe part 68. The anode off-gas and the cooling off-gas are each divided into micro flows by the gas flow dividing unit 74 and mixed in the mixing space 76. At this time, as schematically shown in FIG. 4, a shearing force acts on each of the anode off-gas A and the cooling off-gas C passing through a large number of microchannels that are flat in cross section, and the anode off-gas A and the cooling off-gas C A high shearing force based on the difference in the flow velocity of protrusion into the mixing space 76 acts on the. For this reason, the anode off-gas A and the cooling off-gas C protruding into the mixing space 76 diffuse in the flow direction or form vortices and are efficiently mixed with the counterpart gas to become the mixed gas M.

  The mixed gas M mixed in the mixing space 76 of the mixer 60 is introduced into each heating unit 48 and contacts the oxidation catalyst 49 to cause catalytic combustion. The heat generated by the catalytic combustion is supplied to the adjacent reforming unit 46 through the partition wall 50, and the reforming reaction that is an endothermic reaction in the reforming unit 46 is maintained. That is, hydrogen supply to the fuel cell 14 and power generation by the fuel cell 14 are maintained. The combustion exhaust gas generated by the heating unit 48 is purified by the exhaust unit 64 introduced via the exhaust gas line 62 and exhausted outside the system.

  Here, since the hydrogen supply device 10 is provided with the mixer 60 that mixes the anode off gas and the cooling off gas before supplying them to the heating unit 48, the anode off gas and the cooling are compared with a configuration without such a mixer. The mixing time with the off gas, that is, the gas phase residence time in which the anode off gas and the cooling off gas contact with each other in the gas phase due to the mixing before the contact with the oxidation catalyst 49 is shortened.

  In particular, the mixer 60 has a configuration in which the anode off-gas and the cooling off-gas, which are divided into a large number of microstreams independently (before mixing), are mixed in the mixing space 76, so that uniform mixing is easily promoted. In addition, the occurrence of locally high flammable gas concentrations is suppressed. Further, in particular, the gas flow dividing portion of the mixer 60 is configured by alternately laminating a large number of combustible gas dividing channels and combustion supporting gas dividing channels each formed in a flat shape. A high shearing force acts on the anode off gas and the cooling off gas, and these gases are efficiently mixed. That is, the mixed gas in the mixed space 76 is a local high-concentration portion, such as a collection of minute mixed gases in which the mixing ratio that substantially matches the macroscopic mixing ratio of the anode off-gas and the cooling off-gas is also secured microscopically. Is very uniformly mixed. Moreover, since the gas divided into minute amounts is mixed by the action of high shearing force as described above, the spatial distance and mixing time required for the uniform mixing of the anode off gas and the cooling off gas, that is, the gas phase of the mixed gas. Stay time is shortened.

  For this reason, in the hydrogen supply device 10, the anode off-gas and the cooling off-gas can be passed in a short time while being reliably mixed in the short-distance mixing space 76, and self-ignition of the anode off-gas (the combustible component therein) is suppressed. can do. As a result, in the hydrogen supply device 10, the anode off-gas introduced into the mixer 60 (heating unit 48) at 400 ° C. to 500 ° C. comes into contact with the cooling off-gas having a temperature in the same region to cause vapor phase combustion accompanying self-ignition. Is suppressed. Even if gas phase combustion occurs, the anode off gas and the cooling off gas are uniformly mixed by the mixer 60, thereby preventing a portion where the flammable component has a locally high concentration from occurring and heating. The combustion temperature in the part 48 is suppressed.

  By the way, for example, when the operation of the fuel cell 14 fluctuates (such as when the output suddenly increases), a high concentration portion of the combustible component locally generated in the mixed gas supplied to the heating unit 48 comes into contact with the oxidation catalyst 49 and abnormal combustion ( In the case where local high-temperature catalyst combustion occurs, the temperature distribution in the heating unit 48 is such that the temperature of the mixed gas inlet 48A is high as shown by an imaginary line from the state shown by a solid line in FIG. May be transferred to. Thus, when the temperature of the mixed gas inlet 48A rises, the output signal of the temperature sensor 90 exceeds the threshold value. Then, the control device 88 controls the valve 84 in order to suppress self-ignition of the anode off gas. This control will be described below with reference to the flowchart shown in FIG.

  The controller 88 inputs the output signal of the temperature sensor 90 in step S10, and proceeds to step S12. In step S12, based on the output signal of the temperature sensor 90, whether or not the mixed gas temperature T in the vicinity of the mixed gas inlet 48A of the heating unit 48 exceeds the set temperature Tb (directly, the output signal of the temperature sensor 90 is a threshold value). Or not). When it is determined that the mixed gas temperature T is equal to or lower than the set temperature Tb, the process proceeds to step S14, and it is determined whether or not the valve 84 is fully closed. If the valve 84 is not fully closed, the process proceeds to step S16 and the valve 84 is fully closed. If the valve 84 is fully closed, the process directly returns from step S14 to step S10.

  On the other hand, if it is determined that the mixed gas temperature T exceeds the set temperature Tb, the control device 88 proceeds to step S16 to open the valve 84 and proceeds to step S18, and the opening degree corresponding to the mixed gas temperature T is reached. Then, the valve 84 is opened. For example, the control device 88 outputs an opening command to the valve 84 based on the relationship between the pre-stored mixed gas temperature and the opening degree of the valve 84 to open the valve to a predetermined opening degree. Next, the control device 88 returns to step S10. Therefore, during the period when it is determined in step S14 that the mixed gas temperature T exceeds the set temperature Tb, the valve 84 changes the opening according to the mixed gas temperature T. That is, the valve opening is increased when the mixed gas temperature rises, the valve opening is decreased when the mixed gas temperature decreases, and the valve 84 is fully closed when the mixed gas temperature falls below the set temperature Tb.

  When the valve 84 is opened, a part of the combustion exhaust gas generated in the heating unit 48 is joined to the cooling off gas line 44 via the exhaust return line 82 according to the opening degree of the valve 84 by the suction action of the ejector 92. . The combustion exhaust gas includes unused oxygen (combustion gas) depending on the excess air ratio of the cooling off-gas introduced into the heating unit 48 (and the combustion exhaust gas returned from the exhaust return line 82), and carbon dioxide, water vapor, and nitrogen. Since this gas contains combustion-supporting gas and has a lower oxygen partial pressure (concentration) than air (cooling off gas), the oxygen partial pressure of the gas supplied from the support-supporting gas introduction pipe 68 to the mixer 60 is reduced. To do. That is, oxygen in the cooling off gas before protruding into the mixing space 76 is diluted. As a result, the generation of a locally oxygen-rich region immediately after projecting into the mixing space 76 of the mixer 60 is avoided, and self-ignition of the anode off gas is suppressed.

  In addition, since the oxygen partial pressure of the mixed gas is reduced, the reaction rate of the combustion reaction in the heating unit 48 is slowed. In other words, the combustion start position of the mixed gas is separated from the mixed gas inlet 48A (at the back). The temperature in the vicinity of the mixed gas inlet 48A of the heating unit 48 decreases. FIG. 10 shows the relationship between the oxygen partial pressure of the mixed gas and the inlet temperature (maximum temperature) of the heating unit 48. From this figure, it can be seen that the inlet temperature of the heating section 48 decreases as the oxygen partial pressure decreases. As described above, the self-ignition of the anode off gas is more effectively suppressed. In FIG. 10, a mixed gas of hydrogen and carbon dioxide is supplied to the combustible gas introduction pipe portion 66 of the mixer 60, and air (corresponding to an excess air ratio of 1 with respect to the hydrogen) is supplied to the support gas introduction pipe portion 68. The heating unit 48 is configured to supply a mixed gas with carbon dioxide and increase the amount of carbon dioxide supplied to the combustible gas introducing unit 66 together with hydrogen while reducing the amount of carbon dioxide supplied to the supporting gas introducing pipe unit 68 together with air. This is a result of measuring a change in the inlet temperature of the heating unit 48 when the oxygen partial pressure is changed so that the composition of the mixed gas supplied to the gas becomes constant (macroscopically).

  And the temperature suppression effect of this heating part 48 is effectively implement | achieved by applying combustion exhaust gas circulation (oxygen partial pressure fall) control to the structure provided with the mixer 60. FIG. Here, FIG. 11 shows experimental results showing the effect of reducing the maximum temperature (inlet temperature) in the heating section 48 by the mixer 60. In the configuration in which the mixer 60 is provided, a mixed gas of hydrogen and carbon dioxide is supplied to the combustible gas introduction pipe portion 66 and air (to the hydrogen) is supplied to the combustion support gas introduction pipe portion 68 as in the case of FIG. A mixed gas of an excess air ratio of 1) and carbon dioxide was supplied. In the square plot, the amount of carbon dioxide introduced into the combustible gas introduction unit 66 together with hydrogen is defined as the amount corresponding to the case where the excess air ratio is 2 corresponding to the heat capacity, and the amount of carbon dioxide introduced into the combustion supporting gas introduction unit 68 together with air is defined as the heat capacity. The inlet temperature of the heating unit 48 when the amount corresponding to the case where the excess air ratio is 1 is equivalent, that is, when the exhaust gas circulation control is not performed is shown. The circle plot shows the amount of carbon dioxide introduced into the combustible gas introduction unit 66 together with hydrogen as the amount corresponding to the case where the excess air ratio is 0.8 corresponding to the heat capacity, and is introduced into the combustion supporting gas introduction unit 68 together with air. The inlet temperature of the heating unit 48 when the amount of carbon is equivalent to the heat capacity and the amount corresponding to the excess air ratio of 1.2, that is, when the exhaust gas circulation control is performed (result of reduction in oxygen partial pressure). Indicates. On the other hand, in the configuration without a mixer, hydrogen, air (corresponding to an excess air ratio of 1 with respect to hydrogen), carbon dioxide (corresponding to a heat capacity) so that the amount and composition of the mixed gas are the same as when the mixer 60 is provided. The amount corresponding to the case where the excess air ratio is 3) was supplied to the heating unit 48 in a lump. That is, the experimental conditions of each plot shown in FIG. 11 are determined so that the composition of the mixed gas supplied to the heating unit 48 is constant. For this reason, in the structure which is not provided with the mixer 60, there is no difference by the presence or absence of combustion exhaust gas circulation control.

  As can be seen from FIG. 11 described above, in the configuration provided with the mixer 60, the exhaust gas circulation control is performed, so that the maximum temperature in the heating unit 48 is remarkably shown as the difference between the round plot and the square plot. It was confirmed that it was reduced (suppressed). In other words, in the configuration in which the combustion exhaust gas circulation control is performed, it is confirmed that the maximum temperature in the heating unit 48 is significantly reduced by providing the mixer 60 as shown by the difference depending on the presence or absence of the mixer 60. It was. As a result, in the hydrogen supply device 10, the components of the heating unit 48, the reforming unit 46, the member (such as the reactor having the partition wall 50), the component material is deteriorated, the oxidation catalyst 49 or the reforming catalyst Deterioration and the like can be prevented or suppressed. Further, the difference between the round plot without the mixer 60 and the square plot with the mixer 60 is grasped as the temperature reduction effect by the mixing 60 when the combustion exhaust gas circulation (oxygen partial pressure reduction) control is not performed. be able to. Therefore, it can be seen that the mixer 60 alone contributes to the inlet temperature lowering effect of the heating unit 48 and contributes to the remarkable temperature lowering effect in combination with the combustion exhaust gas circulation control.

  On the other hand, since the combustion exhaust gas has a temperature corresponding to the combustion temperature of the heating unit 48, the temperature (average temperature) of the combined cooling off-gas is not reduced. For this reason, compared with the structure which introduces dilution gas from the system outside, for example, it is prevented that the thermal efficiency of the hydrogen supply apparatus 10 and the fuel cell system 12 falls. In particular, in this embodiment, the controller 88 adjusts the valve opening of the valve 84, that is, the partial pressure of oxygen as the combustion-supporting gas, according to the temperature of the mixed gas (the final temperature in the heating unit 48). A heat flux close to an appropriate amount from the heating unit 48 to the reforming unit 46 is ensured while suppressing self-ignition at 60 or the heating unit 48. That is, the amount of heat (passing heat amount) supplied from the heating unit 48 to the reforming unit 46 due to excessive supply of combustion exhaust gas may decrease, or the self-ignition suppression effect may decrease due to insufficient circulation of combustion exhaust gas. Is prevented. Further, by using the combustion exhaust gas in the heating unit 48 as a dilution gas, the amount of heat exhausted outside the fuel cell system 12 is reduced.

  As described above, in the hydrogen supply device 10, the anode off-gas and the cooling off-gas at temperatures corresponding to the operating temperature of the fuel cell 14 are introduced into the heating unit 48 (mixer 60) as combustible gas (fuel) and combustion support gas, respectively. A configuration with high thermal efficiency with little sensible heat loss due to the gas temperature rise in the section 48 was realized. In addition, in the hydrogen supply device 10, the temperature range of the fuel gas generated in the reforming unit 46 is made substantially the same as the operating temperature range of the fuel cell 14, so that the fuel cell system 12 including the hydrogen consuming device 10 includes A configuration that improves thermal efficiency was realized.

  Thus, in the hydrogen supply apparatus 10 according to the present embodiment, it is possible to prevent the self-ignition of the combustible gas from occurring in the heating unit 48 for heating the reforming unit 46.

  The hydrogen supply device 10 is configured (controlled) so as to reduce the flow rate of the cooling off gas (partially discharged outside the system) when opening the valve 84 and circulating the combustion exhaust gas to the cooling off gas line 44. May be. In particular, since unused oxygen is also contained in the combustion exhaust gas, the supply amount of the cooling off gas (combustion gas) can be greatly reduced. This configuration saves, for example, the amount of introduced support gas and heat for heating the support gas in a configuration in which the support gas is introduced from outside the system (such as a configuration in which the fuel cell 14 is cooled with a liquid refrigerant). The efficiency of the hydrogen supply device 10 can be improved. Moreover, by reducing the supply amount of combustion-supporting gas (air) as described above, the load (energy consumption) of the air supply pump is reduced, and the efficiency of the entire apparatus can be improved. Furthermore, the reduction in the flow rate is more effective in reducing the load because it shows an effect in reducing the pressure loss.

  Next, another embodiment of the present invention will be described. Note that components / parts that are basically the same as those in the first embodiment or the previous configuration are denoted by the same reference numerals as those in the first embodiment or the previous configuration, and description thereof is omitted.

(Second Embodiment)
FIG. 12 shows a fuel cell system 102 to which the hydrogen supply device 100 according to the second embodiment is applied. As shown in this figure, the hydrogen supply device 100 includes an exhaust return line 104 that connects the exhaust line 62 and the anode off-gas line 58 in place of the exhaust return line 82. The ejector 92 is disposed at the junction of the exhaust return line 104 in the anode off gas line 58. The exhaust return line 104 is provided with a valve 84 and a check valve 86. The hydrogen supply device 100 also includes a bypass line 106 that allows the cooling off gas line 44 and the exhaust part 64 to communicate with each other. The bypass line 106 includes a check valve that prevents gas flow from the exhaust part 64 to the cooling off gas line. 108 and a valve 110 which is a control valve similar to the valve 84 is disposed. The valve 110, together with the temperature sensor 90 and the valve 84, is electrically connected to a control device 112 provided in place of the control device 88.

  The control device 112 controls the excess air ratio in the heating unit 48 by adjusting the opening degree of the valve 110. When the control device 112 determines that the mixed gas temperature T at the inlet of the heating unit 48 exceeds the set temperature Tb based on the output signal of the temperature sensor 90, the control device 112 opens the valve 84 (also, the valve 84). The ejector 92 is indirectly actuated by opening the. This control is the same as the control according to the flowchart shown in FIG. Then, the control device 112 increases the opening amount of the valve 110 so that the oxygen in the combustion exhaust gas joined to the anode off gas line 58 becomes a predetermined concentration or less when the valve 84 is opened by performing this control. That is, it is configured to reduce unused oxygen in the combustion exhaust gas by reducing the excess air ratio. Thereby, in the hydrogen supply apparatus 100, when the combustion exhaust gas is merged with the anode off gas, self-ignition is not caused.

  Operations and effects different from those of the first embodiment of the hydrogen supply apparatus 100 according to the second embodiment described above will be described. In the hydrogen supply device 100, the control device 112 that determines that the mixed gas temperature T exceeds the set temperature Tb based on the output signal of the temperature sensor 90 opens the valve 84 to an opening degree corresponding to the mixed gas temperature T. . When the valve 84 is opened, a part of the combustion exhaust gas generated in the heating unit 48 merges with the anode off-gas line 58 via the exhaust return line 82 according to the opening degree of the valve 84. Thereby, the partial pressure (hereinafter referred to as hydrogen partial pressure) of the combustible component of the gas supplied from the combustible gas introduction pipe portion 66 to the mixer 60 is lowered. That is, the combustible component in the anode off gas is diluted. This avoids the generation of a combustible fuel-rich region locally immediately after projecting into the mixing space 76 of the mixer 60, and suppresses self-ignition of the anode off gas.

  In addition, since the hydrogen partial pressure of the mixed gas is reduced, the reaction rate of the combustion reaction in the heating unit 48 is slowed. In other words, the combustion start position of the mixed gas is separated from the mixed gas inlet 48A (at the back). The temperature in the vicinity of the mixed gas inlet 48A of the heating unit 48 decreases. FIG. 13 shows the relationship between the hydrogen partial pressure of the mixed gas and the inlet temperature (maximum temperature) of the heating unit 48. From this figure, it can be seen that the inlet temperature of the heating section 48 decreases as the hydrogen partial pressure decreases. As described above, the self-ignition of the anode off gas is more effectively suppressed. In FIG. 13, a mixed gas of hydrogen and carbon dioxide is supplied to the combustible gas introduction pipe portion 66 of the mixer 60, and air (corresponding to an excess air ratio of 1 with respect to the hydrogen) is supplied to the support gas introduction pipe portion 68. The heating unit 48 is configured to supply a mixed gas with carbon dioxide and increase the amount of carbon dioxide supplied to the supporting gas introduction unit 68 together with air while reducing the amount of carbon dioxide supplied to the combustible gas introduction pipe unit 66 together with hydrogen. This is a result of measuring a change in the inlet temperature of the heating unit 48 when the oxygen partial pressure is changed so that the composition of the mixed gas supplied to the gas becomes constant (macroscopically). Although not shown in the figure, in the configuration for performing the combustion exhaust gas circulation (hydrogen partial pressure reduction) control, as in the first embodiment, by providing the mixer 60, the heating unit 48 by the combustion exhaust gas circulation control is provided. A temperature lowering effect is obtained.

  On the other hand, since the combustion exhaust gas has a temperature corresponding to the combustion temperature of the heating unit 48, the temperature (average temperature) of the joined anode off-gas does not decrease. For this reason, compared with the structure which introduce | transduces dilution gas from the system outside, for example, it is prevented that the thermal efficiency of the hydrogen supply apparatus 100 and the fuel cell system 102 falls. In particular, in this embodiment, the control device 112 adjusts the valve opening of the valve 84, that is, the hydrogen partial pressure, which is the combustible gas concentration, according to the temperature of the mixed gas (the final temperature in the heating unit 48). A heat flux close to an appropriate amount from the heating unit 48 to the reforming unit 46 is ensured while suppressing self-ignition at 60 or the heating unit 48. That is, it is possible to prevent the amount of heat passing from the heating unit 48 to the reforming unit 46 from being excessively supplied by the combustion exhaust gas, or reducing the self-ignition suppression effect due to the insufficient circulation amount of the combustion exhaust gas. Further, by using the combustion exhaust gas in the heating unit 48 as a dilution gas, the amount of heat exhausted outside the fuel cell system 12 is reduced.

  As described above, the hydrogen supply device 100 introduces the anode off-gas and the cooling off-gas at temperatures corresponding to the operating temperature of the fuel cell 14 into the heating unit 48 (mixer 60) as the combustible gas (fuel) and the combustion-supporting gas, respectively. A configuration with high thermal efficiency with little sensible heat loss due to the gas temperature rise in the section 48 was realized. Moreover, in the hydrogen supply device 100, the temperature range of the fuel gas generated in the reforming unit 46 is set to be substantially the same as the operating temperature range of the fuel cell 14, so that the fuel cell system 102 including the hydrogen consuming device 10 includes A configuration that improves thermal efficiency was realized.

  Thus, in the hydrogen supply apparatus 100 according to the present embodiment, it is possible to prevent the self-ignition of the combustible gas from occurring in the heating unit 48 for heating the reforming unit 46. As can be seen from a comparison between FIG. 10 and FIG. 13, the oxygen partial pressure reduction control (first embodiment) is performed under the condition that the composition of the mixed gas mixed by the mixer 60 is constant (same). The effect of reducing the maximum temperature of the heating unit 48 is greater when performed than when performing hydrogen partial pressure reduction control (second embodiment).

(Third embodiment)
FIG. 14 shows a fuel cell system 122 to which the hydrogen supply device 120 according to the third embodiment is applied. As shown in this figure, the hydrogen supply device 120 includes an exhaust return line 124 that communicates the exhaust line 62 with the cooling off-gas line 44 and the anode off-gas line 58 in place of the exhaust return lines 82 and 104. Specifically, in the exhaust return line 124, a combustion support side branch line 124A connected to the cooling off gas line 44 and a combustible side branch line 124B connected to the anode off gas line 58 are branched at the branch portion 124C. . The ejectors 92 are disposed at the joining portion of the combustion supporting branch line 124A in the cooling off gas line 44 and the joining portion of the combustible side branch line 124B in the anode off gas line 58, respectively. Further, a valve 84 and a check valve 86 are disposed on the exhaust line 62 side with respect to the branching portion 124 </ b> C in the exhaust return line 124. The other configuration of the hydrogen supply device 120 is the same as the corresponding configuration of the hydrogen supply device 100. Therefore, the control device 112 configuring the hydrogen supply device 120 is configured to perform the same control as in the second embodiment.

  In the hydrogen supply device 120 according to the third embodiment described above, the combustion exhaust gas that is a dilution gas is introduced into both the cooling off-gas line 44 and the anode off-gas line 58 when the control device 112 opens the valve 84. For this reason, a mixed gas in which the cooling off gas having a reduced oxygen partial pressure and the anode off gas having a reduced hydrogen partial pressure are mixed in the mixer 60 is introduced into the heating unit 48, and an oxygen-rich region is added to the mixed gas. In addition, the generation of the combustible fuel-rich region is effectively suppressed. Thereby, in the hydrogen supply device 120, the self-ignition of the anode off gas is suppressed. Other functions and effects of the hydrogen supply device 120 are the same as those of the hydrogen supply device 10 or the hydrogen supply device 100.

  In the above-described embodiment, the hydrogen supply device 10 supplies fuel gas to the fuel cell 14 as the hydrogen consuming device. However, the present invention is not limited to this. For example, the exhaust gas is purified (desulfurization, etc.) The water supply device according to this embodiment may be applied to a use for supplying hydrogen to a purification device as a hydrogen consuming device.

  Further, the hydrogen supply devices 10, 100, 120 can use the valve opening of the valve 84 (the driving amount of the valve driving device) as a control parameter of the valve 84 instead of the mixed gas temperature at the inlet of the heating unit 48. . In this case, by setting the valve opening, that is, the amount of incombustible components in the mixed gas as a control target, it is possible to prevent self-ignition by the incombustible components and to suppress a temperature rise due to an increase in heat capacity (sensible heat). In this configuration, it is desirable that the control device 88 or another control device electrically connected to the control device 88 performs the excess air ratio control in the heating unit 48. Further, the valve 84 may be an open / close valve, and the controller 88 may be configured to perform control to open the valve 84 during a period when the mixed gas temperature T exceeds the set temperature Tb.

(Fourth embodiment)
FIG. 15 shows a fuel cell system 142 to which the hydrogen supply device 140 according to the fourth embodiment is applied. As shown in this figure, the hydrogen supply device 140 does not include the exhaust return lines 82, 104, 124, the control devices 88, 112, etc., and does not perform combustion exhaust gas circulation (oxygen partial pressure reduction or hydrogen partial pressure reduction) control. It is configured. The other configuration of the hydrogen supply device 140 is the same as that of the hydrogen supply device 10.

  In the hydrogen supply device 140 according to the fourth embodiment described above, the anode off-gas and the cooling off-gas are mixed by the mixer 60 and introduced into the heating unit 48 as a mixed gas. For this reason, in the mixed gas, the generation of a part having a high oxygen concentration and a part having a high concentration of combustible components is suppressed, and self-ignition of the anode off-gas is suppressed. Compared to the configuration without the mixer 60, the inlet of the heating unit 48 is shown in FIG. 11 as shown by the difference between the square plot without the mixer and the square plot with the mixer. Since the temperature is suppressed, the self-ignition of the anode off gas is more effectively suppressed.

1 is a schematic diagram showing a schematic overall configuration of a fuel cell system to which a hydrogen supply device according to an embodiment of the present invention is applied. It is a plane sectional view showing the whole mixer composition which constitutes the hydrogen supply device concerning the embodiment of the present invention. It is a perspective view which decomposes | disassembles and shows the flow-path division | segmentation structure of the mixer which comprises the hydrogen supply apparatus which concerns on embodiment of this invention. It is a sectional side view which shows typically the gas mixing state by the mixer which comprises the hydrogen supply apparatus which concerns on embodiment of this invention. It is typical sectional drawing of the fuel cell single cell which receives supply of the hydrogen supply apparatus-fuel gas which concerns on embodiment of this invention. It is a diagram which shows the performance of the mixer which comprises the hydrogen supply apparatus which concerns on embodiment of this invention, Comprising: (A) is a diagram which shows the mixed gas flow velocity distribution in the lamination direction of a division | segmentation flow path, (B) is division | segmentation. It is a diagram which shows the helium gas concentration in the mixed gas in the lamination direction of a flow path. It is a diagram which shows the performance of the mixer which comprises the hydrogen supply apparatus which concerns on embodiment of this invention, Comprising: (A) is a diagram which shows the mixed gas flow velocity distribution in the width direction of a division flow path, (B) is division It is a diagram which shows the helium gas concentration in the mixed gas in the width direction of a flow path. It is a diagram which shows the temperature distribution along the gas flow direction in the heating part which comprises the hydrogen supply apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the control flow by the control apparatus which comprises the hydrogen supply apparatus which concerns on the 1st Embodiment of this invention. It is a diagram which shows the relationship between the inlet temperature of the heating part of the hydrogen supply apparatus which concerns on the 1st Embodiment of this invention, and oxygen partial pressure. It is a graph which shows the experimental result which compared the heating part maximum temperature by the presence or absence of the mixer which comprises the hydrogen supply apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the schematic whole structure of the fuel cell system with which the hydrogen supply apparatus which concerns on the 2nd Embodiment of this invention was applied. It is a diagram which shows the relationship between the inlet temperature of the heating part of the hydrogen supply apparatus which concerns on the 2nd Embodiment of this invention, and hydrogen partial pressure. It is a schematic diagram which shows the schematic whole structure of the fuel cell system with which the hydrogen supply apparatus which concerns on the 3rd Embodiment of this invention was applied. It is a schematic diagram which shows the schematic whole structure of the fuel cell system with which the hydrogen supply apparatus which concerns on the 3rd Embodiment of this invention was applied.

Explanation of symbols

10 Hydrogen supply device 14 Fuel cell (hydrogen supply device)
44 Cooling off gas line (supporting gas introduction path)
46 reforming section 48 heating section 58 anode off-gas line (flammable gas introduction path)
60 Mixer 76 Mixing space (mixing section)
78C Combustible gas division flow path 80C Combustion gas division flow path 100/120/140 Hydrogen supply device

Claims (7)

A reforming section for performing a reforming process for generating a fuel gas containing hydrogen from the supplied raw material;
Heating that supplies the combustible gas and the combustion support gas to the catalyst to cause catalytic combustion, and supplies the heat generated in the catalytic combustion to the reforming unit as heat for performing the reforming step. And
A mixer for mixing the combustible gas and the combustion-supporting gas before being supplied to the heating unit;
A hydrogen supply device comprising: A hydrogen supply device for supplying a hydrogen-containing fuel gas to a hydrogen consuming device that operates at a predetermined operating temperature,
A reforming section for performing a reforming process for generating a fuel gas containing hydrogen from the supplied raw material;
A heating unit for bringing the supplied combustible gas and supporting gas into contact with the catalyst to cause catalytic combustion, and supplying heat generated by the catalytic combustion to the reforming unit as heat for performing the reforming step; ,
A combustible gas introduction path for introducing a component of the fuel gas that is not consumed by the hydrogen consuming device into the heating unit as the combustible gas;
A mixer provided in the combustible gas introduction path, for mixing the combustible gas and the combustion supporting gas;
A hydrogen supply device comprising: A hydrogen supply device for supplying a hydrogen-containing fuel gas to a hydrogen consuming device that operates at a predetermined operating temperature,
A reforming section for performing a reforming process for generating a fuel gas containing hydrogen from the supplied raw material;
A heating unit for bringing the supplied combustible gas and supporting gas into contact with the catalyst to cause catalytic combustion, and supplying heat generated by the catalytic combustion to the reforming unit as heat for performing the reforming step; ,
A combustion support gas introduction path for introducing the oxygen-containing refrigerant after cooling the hydrogen consumption device in order to operate the hydrogen consumption device at the predetermined operating temperature as the combustion support gas into the heating unit;
A mixer that is provided in the combustion-supporting gas introduction path and mixes the combustible gas and the combustion-supporting gas;
A hydrogen supply device comprising:   The fuel gas further includes a combustible gas introduction path that introduces a component that is not consumed by the hydrogen consuming device into the heating section as the combustible gas, and the merging section between the combustible gas introduction path and the combustion support gas introduction path The hydrogen supply apparatus according to claim 3, wherein a mixer is disposed.   The hydrogen supply apparatus according to claim 4, wherein an operating temperature of the hydrogen consuming apparatus is within a range of 300 ° C. to 600 ° C. The mixer is
A gas flow dividing section that divides the combustible gas and the combustion supporting gas into a plurality of flow paths independently of each other;
A mixing unit that is disposed between the gas flow dividing unit and the heating unit and mixes the combustible gas and the combustion supporting gas introduced from each flow path divided in the gas flow dividing unit;
The hydrogen supply device according to any one of claims 1 to 5, comprising:   The gas flow dividing unit is divided into a plurality of flat combustible gas dividing passages through which the combustible gas passes, and a plurality of flat supporting gas dividing passages through which the combustion supporting gas passes. The hydrogen supply device according to claim 6, wherein the hydrogen supply device is configured to be alternately stacked in a short direction of the flow path.

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