JP2005255458A - Hydrogen production apparatus and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen production apparatus in which the quantity of steam and S/C of a raw material (the ratio of the number of molecules of steam to the number of atoms of carbon in the raw material) supplied to a reforming part is stably kept to a prescribed value in spite of the frequent change of the feed rate of water supplied to a 2nd water evaporation part 6 and which is capable of stabilizing the power generation of a fuel cell and improving the service life of the fuel cell and to provide the fuel cell power generation system with the same. <P>SOLUTION: A water supply part 1 for supplying water to a 1st water evaporation part 5 and the 2nd water evaporation part and a branched part for supplying water respectively to the 1st water evaporation part 5 and the 2nd water evaporation part 6 is provided on the water passage through which the water supplied from the water supply part 1 flows. A flow meter 2 for measuring the flow rate of water in a water passage between the branched part and the water supply part and a flow control part 3 for controlling the flow rate of water in a water passage between the branched part and the 2nd water evaporation part 6 are provided. The flow control part 3 controls the flow rate of water so that the temperature detected by a temperature detector 12 in a transforming part 8 becomes a prescribed temperature by heat exchange. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, a raw material containing an organic compound composed of at least carbon and hydrogen such as city gas, LP gas, and methanol is reformed using steam (hereinafter referred to as steam reforming or reforming reaction) to generate hydrogen. The present invention relates to a hydrogen generation apparatus that generates reformed gas containing the fuel, and a fuel cell system including the same.

  A conventional hydrogen generator and fuel cell system will be described with reference to FIG.

  According to Japanese Patent Application No. 2003-21847, which is an unpublished in-house application, the reforming unit 7 for generating a reformed gas mainly composed of hydrogen by steam reforming a raw material such as city gas or LP gas is, for example, a fuel cell 10. It is used for the production of hydrogen used as a power generation material. Since the reforming reaction in the reforming section 7 is an endothermic reaction, it is necessary to keep the reforming section 7 at a temperature of about 550 to 800 ° C. in order to maintain the reforming reaction. For this reason, the reforming unit 7 is provided with a heating unit 20 such as a burner, and the reforming is performed using a high-temperature combustion gas obtained from the heating unit 20 or a radiator that emits radiant heat of the combustion gas. Part 7 is heated. Here, the steam used for the steam reforming is generated by the first water evaporation unit 5 and the second water evaporation unit 6 which are provided separately. Here, water is supplied from the first water supply unit 23 and the second water supply unit 25 to these evaporation units, respectively, and the flow rates of these waters are measured by the first flow meter 24 and the second flow meter 26, respectively. doing.

  On the other hand, the reformed gas obtained in the reforming section of the hydrogen generator is mainly composed of hydrogen as described above, but contains carbon monoxide (hereinafter referred to as CO) by-produced in the reforming reaction. . When the reformed gas containing CO is directly supplied to the fuel cell 4 in this way, the CO reduces the activity of the catalyst in the fuel cell 4. Therefore, in the hydrogen generator, in order to remove CO, a shift unit 8 that converts CO contained in the reformed gas into CO 2 by a shift reaction is disposed downstream of the reformer.

  In this CO shift part, the temperature is set to 180 to 400 ° C., which is optimal for the shift reaction, in order to efficiently perform the shift reaction. The reformed gas that has passed through the shift converter 8 is supplied to the fuel cell after the CO concentration is sufficiently reduced to about 100 ppm by a selective oxidation reaction in a purifier (not shown). This fuel cell generates electric power using hydrogen and oxygen-containing oxidant (for example, air) in the reformed gas with sufficiently reduced CO as described above. Hydrogen that has not been consumed in the power generation reaction of the fuel cell is discharged from the fuel cell, and then supplied to the burner and burned.

  In the above hydrogen generator, in order to generate water vapor in the first water evaporation unit 5 and the second water evaporation unit 6, the first water evaporation unit 5 uses the combustion exhaust gas of the heating unit 20 as a heat source, and the second The water evaporation section 6 exchanges heat with the shift section 8 and uses the heat of the shift section 8 as a heat source. At this time, in particular, the flow rate of water supplied from the second supply unit to the second water evaporation unit is a temperature set in advance so that the temperature of the shift reaction maintains the above-described optimal temperature range (for example, 200 ° C. ) To be controlled based on the detected temperature of the temperature detection unit 12 provided in the transformation unit.

By the way, in the conventional hydrogen generator, the second water supply unit controls the flow rate of water so that the temperature detected by the temperature detection unit 12 becomes a predetermined temperature (for example, 200 ° C.) as described above. The ratio of the number of water molecules in the water vapor supplied to the reforming unit 7 and the number of carbon atoms contained in the raw material (hereinafter referred to as S / C) is frequently changed depending on the temperature of the water. There is a problem that it cannot be made constant (for example, S / C target value = 3). More specifically, if the S / C is deviated from the target value, carbon may be deposited on the reforming catalyst, leading to a risk of catalyst deterioration. If it shift | deviates, since the calorie | heat amount for making it into water vapor | steam will become large, the efficiency of a modification part will fall.

  In addition, if the amount of water vapor supplied to the reforming section changes frequently as described above, the moisture in the reformed gas generated in the reforming section, i.e., the dew point, also changes. This leads to a decrease in battery life.

  In addition, when the fuel cell is a solid polymer fuel cell, the moisture in the reformed gas fluctuates, and if the solid polymer membrane is too dry, the ionic conductivity of the polymer electrolyte membrane is not fully exhibited. There has been a problem in that power reduction is caused and problems such as flooding in which water is clogged in the gas flow path provided in the separator of the fuel cell are liable to occur if the substrate is too wet.

  Therefore, in view of the problems of these conventional hydrogen generators, the present invention is directed to the steam and raw material S supplied to the reforming unit, regardless of frequent changes in the flow rate of water supplied to the second water evaporation unit. It is an object of the present invention to provide a hydrogen generator that stably maintains / C at a predetermined value, stabilizes power generation and improves the life of the fuel cell, and a fuel cell power generation system including the same.

  In order to solve the above problems, a hydrogen generator according to the present invention includes a reforming unit that generates a reformed gas containing hydrogen by a reforming reaction using steam and a raw material, and a heating unit that heats the reforming unit. A first water evaporation unit for generating the water vapor using the combustion exhaust gas of the heating unit, a conversion unit for converting carbon monoxide in the reformed gas into carbon dioxide by a shift reaction, and the conversion unit A second water evaporating unit configured to exchange heat with the metamorphic unit and generating water vapor using the heat of the metamorphic unit, a temperature detecting unit detecting the temperature of the metamorphic unit, the first water evaporating unit, and the second water evaporating unit A branch for supplying water to each of the first water evaporation unit and the second water evaporation unit on a water path through which water output from the water supply unit circulates A water path between the branch part and the water supply part. A flow meter for measuring a flow rate, and a flow rate adjusting unit for adjusting a flow rate of water in a water path between the branching unit and the second water evaporation unit, and the flow rate adjusting unit is configured to perform the heat exchange The flow rate of water is adjusted so that the temperature detected by the temperature detector becomes a predetermined temperature.

  Further, the hydrogen generator of the present invention is configured so that the total amount of the water amount X supplied to the first water evaporation unit and the water amount Y supplied to the second water evaporation unit is maintained at a predetermined value. The water supply unit is controlled based on the value of.

  The hydrogen generator of the present invention is characterized in that a pump is used instead of the water supply unit and the flow meter, and the flow rate control unit is a pump.

  The fuel cell system of the present invention includes the above-described hydrogen generator of the present invention and a fuel cell that generates power using hydrogen and an oxidant gas supplied from the hydrogen generator.

  ADVANTAGE OF THE INVENTION According to this invention, S / C in a reforming part is stabilized, and the hydrogen production apparatus with which the dew point of reformed gas is stabilized is obtained. Further, in the fuel cell power generation system using this hydrogen generator, the stability of the fuel cell power generation is improved due to the stability of the dew point.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings show the characteristic configuration of the hydrogen generator according to the embodiment and the fuel cell power generation system including the device, and the illustration and detailed description of the conventionally known configuration are omitted. To do.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a configuration of a hydrogen generator according to Embodiment 1 of the present invention and a fuel cell system including the same.

  As shown in FIG. 1, the hydrogen generator and the fuel cell system of the present embodiment include a reformed gas containing hydrogen by a reforming reaction using a raw material containing an organic compound composed of at least carbon and hydrogen and steam. And heating to heat the reforming unit 7 so that the temperature of the reforming unit 7 can be maintained at an optimum temperature (for example, about 550 ° C. to 800 ° C.). Unit 20, a raw material supply unit (not shown) for supplying raw material to the reforming unit, a first water evaporation unit 5 and a second water evaporation unit 6 for supplying water vapor to the reforming unit 7, Each of the first water evaporation unit 5 and the second water evaporation unit 6 is provided on a water supply unit 1 for supplying water to the evaporation unit and a water path through which water output from the water supply unit 1 flows. A branch for supplying water to the water, the branch and the water supply 1 A flow meter 2 for measuring the flow rate of water in the water path therebetween, a flow rate adjusting unit 3 for adjusting the flow rate of water in the water path between the branching unit and the second water evaporation unit, and in the reformed gas A shift section 8 for reducing carbon monoxide to carbon dioxide by a water vapor shift reaction, a temperature detector 12 for detecting the temperature of the shift section 8, and a hydrogen rich gas and oxygen discharged from the shift section 8 A fuel cell 10 that generates electric power using an oxidant gas contained therein and an oxidant gas supply unit 9 for supplying air as an oxidant gas to the fuel cell 1 are provided.

  Next, the operation of the hydrogen generator of the present embodiment and the fuel cell system including the same will be described. First, city gas, which is one of the raw materials, is supplied by a raw material supply unit (not shown), and at the same time, the water output from the water supply unit 1 branches off in the middle of the water path, and the first water evaporation unit 5 And the second water evaporating unit 6. The water supplied to the first water evaporation unit 5 is heated by the combustion exhaust gas of the heating unit 20 to become water vapor. Further, the water supplied to the second water evaporation unit 6 is converted into water vapor by receiving heat from the transformation unit 8 because the second water evaporation unit 6 is configured to be able to exchange heat with the transformation unit 8.

  Here, the flow rate of the water supplied to the second water evaporation unit 6 is detected so that the temperature detected by the temperature detection unit 12 provided in the transformation unit 8 becomes a predetermined temperature (for example, 200 ° C.). It is adjusted by the flow rate regulator 3 based on the detected temperature of the unit 12. Since the temperature in the shift section can be kept constant at a predetermined temperature suitable for the shift reaction, the CO concentration in the reformed gas can be reduced to a predetermined value or less. Efficiency can be improved because the heat of transformation reaction can be recovered as steam necessary for the reforming reaction.

By the way, in the above-described conventional hydrogen generator, the flow rate of water supplied to the second water evaporator 6 is frequently supplied to the reformer 7 because it fluctuates frequently in order to control the temperature of the shift converter 8. There is a problem that it is difficult to keep the molar ratio (hereinafter referred to as S / C) between the number of water molecules in water vapor and the number of carbon atoms contained in the raw material constant. However, in the present embodiment, the water path provided for each of the first water evaporation unit 5 and the second water evaporation unit 6 becomes a single water path at the branch, and water is supplied from this one path. Since the flow rate of water is measured by the flow meter 2, the sum of the measured value, that is, the amount of water X supplied to the first water evaporation unit and the estimate Y supplied to the second water evaporation unit is By controlling the flow rate of water from the water supply unit so as to be a predetermined value, it becomes possible to maintain the S / C in the reforming unit 7 at a predetermined value regardless of the temperature fluctuation of the shift unit 8. . That is, the flow rate of water from the water supply unit is controlled so as to maintain the S / C at a predetermined value while changing the amount of water supplied to the second water evaporation unit 6 in order to cope with the temperature fluctuation of the transformation unit 8. It becomes possible.

  Further, since the S / C can be controlled to a predetermined value, the moisture in the reformed gas, that is, the dew point is stabilized, and the fuel cell can stably generate power and extend its life.

  The predetermined temperature is a temperature set in advance for controlling the temperature of the shift unit 8 to be within a temperature range (about 550 ° C. to 800 ° C.) optimum for the shift reaction.

  Then, the steam reforming reaction is performed in the reforming unit 7 using the steam generated in the first water evaporation unit 5 and the second water evaporation unit 6 by the above-described operation and the raw material supplied from the raw material supply unit (not shown). As a result, hydrogen-based reformed gas is generated. The reformed gas is supplied to the shift unit 8, and carbon monoxide contained in the reformed gas is converted into carbon dioxide by a reaction due to water vapor shift, and the carbon monoxide concentration is reduced. Thereafter, the reformed gas discharged from the shift unit 8 is supplied to the fuel electrode of the fuel cell 10, and air as the oxidant supplied to the oxidant electrode of the fuel cell 10 reacts with hydrogen in the reformed gas. And generate electricity. Hydrogen in the reformed gas that has not been used for the power generation reaction is discharged from the fuel electrode of the fuel cell 10 and used for the combustion reaction in the heating unit 20.

  In the present embodiment, the fuel off-gas in the fuel cell 10 is used as the combustion fuel gas supplied to the heating unit 20. For example, city gas, methane, LP, and the like are used as the combustion fuel gas. Other hydrocarbon compound fuels such as gas and kerosene may be used.

  In the present embodiment, it is preferable to use a pump instead of the water supply unit 1 and the flow meter 2, and use a pump instead of the flow rate regulator 3. Since this is pressurized by the pump as the water supply unit 1, the discharge pressure of water output from the pump as the flow rate regulator 3 can be increased, so the pressure loss in the second water evaporation unit 6 is large. This is because water can be supplied stably even in this case. Moreover, since the flowmeter 2 can be eliminated, cost reduction can be achieved.

(Embodiment 2)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings show a characteristic configuration of the hydrogen generator according to the present embodiment and a fuel cell power generation system including the device, and the conventionally known configurations are illustrated and described in detail. Omitted.

  FIG. 2 is a schematic cross-sectional view showing the configuration of the hydrogen generator according to Embodiment 2 of the present invention.

  In the present embodiment, first, a hydrogen generator will be described, and then a fuel cell power generation system including the hydrogen generator will be described.

  As shown in FIG. 2, the hydrogen generator includes a burner 20 to which a cylindrical main body 50 whose upper and lower ends are closed, a cylindrical radiation tube 21 is attached, and a heat insulating material 53 that covers the outer periphery of the main body 50. And is composed mainly of. The detailed structure of the hydrogen generator will be described below.

The burner 20 to which the radiation tube 21 is attached is housed and arranged concentrically with the main body 50. The inside of the cylindrical main body 50, specifically, the space between the inner wall of the main body 50 and the radiation tube 21 has a plurality of vertical walls 102 having a concentric cylindrical shape and different lengths in the radial direction and the axial direction. And a plurality of disk-shaped or hollow disk-shaped horizontal walls 103 that are appropriately disposed at predetermined ends of the vertical wall 102. Specifically, a plurality of vertical walls 102 are arranged concentrically upright inside the main body 50 to form a gap 51 between the vertical walls 102, and a desired gas flow is obtained using the gap 51. A predetermined end of the vertical wall 102 is appropriately closed by a horizontal wall 103 so that a path is formed. As a result, the reforming unit 7, the transformation unit 8, and gas passages described later are formed inside the main body 50.

  Each gas flow path is formed in a ring shape in the II ′ cross section in the radial direction of the main body 50, and from the outside toward the inside, the downstream side flow path 14A of the combustion gas flow path 14 having a double structure, double The upstream flow path 11A and the downstream flow path 11B of the reforming raw material flow path 11 having the structure, the reformed gas flow path 32, the reforming unit 7, and the upstream flow path 14B of the combustion gas flow path 14 are sequentially arranged. It is arranged. The downstream flow path 14 </ b> A and the upstream flow path 14 </ b> B of the combustion gas flow path 14 communicate with each other at the bottom by a flow path in the main body radial direction formed by the lateral wall 103. The end of the upstream channel 4B communicates with the burner 20 to which the radiation cylinder 21 is attached, and the end of the downstream channel 4A communicates with the outside through the exhaust gas outlet 18. Further, the upstream flow channel 11A and the downstream flow channel 11B of the reforming raw material flow channel 11 communicate with each other at the bottom by a flow channel in the main body radial direction formed by the lateral wall 103, and the region of the bottom portion that communicates is The first water evaporation section 5 is provided. As will be described later, water is supplied to the first water evaporation section 5 through the upstream flow path 11A to generate first water vapor, and the first water vapor moves through the downstream flow path 11B. Therefore, here, the first water vapor path formed by the upstream flow path 11A and the downstream flow path 11B is referred to as a first water vapor flow path 11D.

  The reforming part 7 has a cylindrical shape and is arranged so as to surround the side part and the upper part of the radiation cylinder 21 via the upstream side flow path 14 </ b> B of the combustion gas flow path 14. A downstream channel 11 </ b> C of the reforming material channel 11 along the upper end surface of the reforming unit 7 is formed by the horizontal wall 103 above the reforming unit 7 in the body axis direction. The downstream flow channel 11C in the main body radial direction thus formed communicates with the downstream flow channel 11B of the reforming raw material flow channel 11 described above. As a result, the downstream end of the reforming raw material flow path 11 communicates with the upper end surface of the reforming section 7. The downstream flow path 11B of the reforming raw material flow path 11 is further extended to the upper side in the main body axial direction, and a second water vapor flow path 30 is formed by this extended portion, as will be described later. Therefore, the second steam channel 30 and the reforming material channel 11 are in communication with each other.

  In addition, a transformation unit 8 is disposed above the reforming unit 7 in the axial direction so as to face the upper end surface of the reforming unit 7. The transformation unit 8 and the reforming unit 7 are communicated with each other through the reformed gas flow path 32. The reformed gas channel 32 has an upstream end communicating with the lower end surface of the reforming unit 7, extending in the main body axial direction so as to surround the outer periphery of the reforming unit 7, and a downstream region of the reforming unit 8. It is formed in the main body radial direction along the upper end surface of. Further, the post-transformation gas flow path 13 is formed by the lower end surface of the metamorphic portion 8 and the lateral wall 103. The downstream end of the post-transformation gas flow path 13 whose upstream end communicates with the metamorphic section 8 communicates with a purification section (not shown) through the post-transform gas outlet 17.

  An upstream channel 11 </ b> A of the reforming material channel 11 is connected to the material supply unit and the water supply unit 1. The flow rate value of water output from the water supply unit 1 is detected by the flow meter 2. Although not shown here, the raw material supply unit includes a raw material supply device and a raw material supply pipe. Further, the second water vapor channel 30 is connected to the flow rate regulator 3. The burner 20 attached to the main body 50 is provided with a combustion air supply port 20a and a combustion fuel gas supply port 20b. Although not shown here, the air supply port 20a is supplied with air. The combustion fuel gas supply port 20b is connected to the combustion gas supply unit.

  The reforming part 7 is formed by filling a gap 51 formed between the vertical walls 102, in which a platinum group metal as a reforming catalyst is supported on a carrier made of a metal oxide formed into a granular shape. ing. The reforming unit 7 is formed inside the apparatus with respect to the reforming material channel 11 and the reforming gas channel 32, and the upper end surface communicates with the reforming material channel 11 and the lower end surface is the reforming gas channel. 32.

The shift portion 8 has a configuration in which a platinum group metal serving as a shift catalyst is dispersed and supported on a support made of a film-like metal oxide formed on a ceramic honeycomb substrate. In addition, a temperature sensor 12 serving as a temperature detector for detecting the internal temperature is disposed in the transformation unit 8. The temperature information of the transformer 8 detected by the temperature sensor 12 is transmitted to the control device 35. And the control apparatus 35 controls the flow volume adjustment part 3 based on this information so that it may mention later, and adjusts the flow volume of the water supplied to the 2nd water vapor flow path 30 from the flow volume regulator 3. FIG.

  The main body 50 and the burner 20 are connected to the post-transformation gas outlet 17, the exhaust gas outlet 18, the air supply port 20 a and the combustion fuel gas supply port 20 b, and the raw material supply unit, the water supply unit 1 and the flow rate regulator 3. Except for the portion, the outer periphery is covered with a heat insulating material 53.

  The downstream flow path 11B of the reforming raw material flow path 11 is connected to the downstream flow path 11C (hereinafter, the moving direction of the mixed raw material gas is changed (deflected) at this connection, and thus this connection is deflected. It extends beyond the metamorphic portion 8 to the upper side in the main body axial direction. The extended end region is disposed so as to be adjacent to the reformed gas channel 32 formed along the upper end surface of the metamorphic portion 8 via the lateral wall 103. Here, in the downstream flow path 11B of the reforming raw material flow path 11 formed in this way, a portion located on the metamorphic section 8 side (that is, the upper side) of the deflection section, in particular, the second water vapor flow Called the path 30.

  Inside the second water vapor channel 30, a second water evaporation unit 6 is formed in a portion adjacent to the reformed gas channel 32 via the lateral wall 103. The second water evaporating unit 6 is configured to be able to store water supplied from the flow rate regulator 3. For example, a container having a predetermined depth made up of a bottom surface and a side surface disposed on the outer periphery of the bottom surface is the second water evaporation unit 6. The second water evaporation section 6 is configured by being disposed in the water vapor flow path 30.

  Next, the operation of the hydrogen generator will be described.

  Fuel gas is supplied to the burner 20 through the combustion fuel gas supply port 20b, and air is supplied to the burner 20 through the combustion air supply port 20a. As the fuel gas for combustion, surplus fuel (so-called fuel off gas) that has not been used in the fuel cell 10 of the fuel cell power generation system is used. Then, diffusion combustion is performed using the supplied fuel off-gas and air. Here, since the burner 20 is surrounded by the radiation cylinder 21, combustion is performed in the radiation cylinder 21, thereby generating high-temperature combustion gas. The heat of the combustion gas is transmitted by radiation to the radially outer side of the main body 50 through the radiation cylinder 21. The reforming catalyst of the reforming unit 7 is heated by such radiant heat, and the combustion gas moves axially upward in the radiation cylinder 21 to directly heat the reforming catalyst. Thereby, the modification part 7 is maintained at the temperature of about 550-800 degreeC. The rising combustion gas moves downward in the axial direction along the vertical wall 102 in the upstream flow path 4B of the combustion gas flow path 4, and further moves upward in the axial direction in the downstream flow path 4A. To the outside from the exhaust gas outlet 18 (arrow i in the figure). Here, as will be described later, in the process in which the combustion gas moves in the combustion gas flow path 4, heat exchange is performed between the heat held by the combustion gas and the water moving in the reforming raw material flow path 11. The heat of the combustion gas is used as latent heat of evaporation in the first water evaporation unit 5.

Source gas (for example, city gas, hydrocarbon gas such as LP gas, alcohol such as methanol) supplied from the source supply unit and containing an organic compound composed of at least carbon and hydrogen and supplied from the water supply unit 1 The water thus supplied is sent to the reforming unit 7 through the reforming material channel 11 as a reforming reaction material. Here, first, the raw material gas and water supplied from each supply unit remain in different substance states (that is, gas and liquid) in the upstream flow channel 11A of the reforming raw material flow channel 11 along the vertical wall 102. And move downward in the axial direction (arrow a in the figure). Then, at the bottom of the upstream flow passage 11A, that is, in the first water evaporation section 5, water evaporates using the heat and radiant heat of the combustion gas described above and the heat from the reforming section 7 described later, Become. This first water evaporation section 5
The water vapor generated in is called the first water vapor. The first water vapor is mixed with the raw material gas, and this mixed raw material gas moves axially upward along the vertical wall 102 in the downstream channel 11B (arrow b in the figure). Then, this mixed raw material gas enters the downstream flow passage 11C of the reforming raw material flow passage 11 formed along the upper end surface of the reforming section 7, and the inside of this flow passage 11C is directed inward along the horizontal wall 103. Are moved to the reforming section 7 (arrow c in the figure).

  The raw material gas and the first water vapor are introduced into the reformer 7 from the upper end surface, and move in the reforming catalyst along the vertical wall 102 in the axial direction downward (arrow d in the figure). During this movement, the first water vapor and the raw material gas are heated to increase the temperature, and a reforming reaction is performed to generate a reformed gas. The reformed gas is mainly composed of hydrogen and contains by-produced CO. Then, the generated reformed gas is discharged from the lower end surface of the reforming unit 7 to the reformed gas channel 32 and moves in the reformed gas channel 32 along the vertical wall 102 in the axial direction upward (FIG. Middle arrow e). Then, it moves in the reformed gas channel 32 along the horizontal wall 103 and reaches the metamorphic section 8 (arrow f in the figure).

  The reformed gas supplied to the shift unit 8 moves downward in the axial direction in the shift catalyst. In this process, a reaction in which CO contained in the reformed gas is converted to CO2, that is, a shift reaction is performed, and a gas after the shift is generated. This modification reaction is an exothermic reaction. The post-transformation gas is ejected vertically downward from the downstream surface of the metamorphic section 8 into the post-transformation gas flow path 13 (arrow g in the figure), and then moves along the horizontal wall 103 in this flow path, and the vertical wall 102 The gas is moved upward in the axial direction along the flow path and taken out from the gas outlet 17 after the transformation (arrow h in the figure). The post-transformation gas taken out from the post-transformation gas outlet 17 is sent to a purification unit (not shown).

  Here, when the reformed gas moves in the reformed gas channel 32 as described above, water is supplied from the flow rate regulator 3 to the second water vapor channel 30. Here, the amount of water supplied from the flow controller 3 to the second water vapor channel 30 is 1/5 or less of the amount of water supplied from the water supply unit 1 to the reforming raw material channel 11. Thus, the water supplied to the second water evaporation unit 6 is temporarily stored in the second water evaporation unit 6.

  Since the second water evaporation unit 6 is in contact with the reformed gas channel 32 via the horizontal wall 103, a part of the heat held by the reformed gas flowing through the reformed gas channel 32 is transmitted via the horizontal wall 103. It is transmitted to the second water evaporation unit 6 and used as latent heat of evaporation in the second water evaporation unit 6. By recovering a part of the retained heat as latent heat of vaporization in this way, the reformed gas that is as hot as the reformer 7 is cooled. Further, the radiant heat from the upstream surface of the transformation unit 8 is also transmitted to the second water evaporation unit 6 through the reformed gas flow path 32 and used as latent heat of evaporation. As a result, even if heat is generated in the metamorphic part 8 due to the metamorphic reaction, the temperature of the metamorphic part 8 can be maintained at 180 to 400 ° C. optimal for the metamorphic reaction. Therefore, the metamorphic reaction is performed stably and efficiently in the metamorphic section 8 to remove CO.

  Here, similarly to the above-described first embodiment, the temperature of the transformation unit 8 is detected by the temperature sensor 12 as a temperature detector, and based on the temperature information, the temperature of the transformation unit 8 is a predetermined temperature (for example, 200 The controller 35 controls the amount of water supplied from the flow rate regulator 3 before the temperature reaches (° C.).

That is, when the temperature of the shift unit 8 is lower than the predetermined temperature optimum for the shift reaction, the control device 35 controls the flow rate regulator 3 to reduce the amount of water supplied from the flow rate regulator 3. For example, when the flow rate regulator 3 has a supply pump and an on-off valve for the supply flow path, the control device 35 reduces the supply amount of water by reducing the output of the pump or closing the on-off valve. Let Thereby, the amount of water supplied to the second water evaporation unit 6 is reduced, and accordingly, the amount of heat of the reformed gas recovered as latent heat of evaporation in the second water evaporation unit 6 is reduced. Therefore, the reformed gas having a large amount of heat is supplied to the shift unit 8, thereby increasing the temperature of the shift unit 8.

  On the other hand, when the temperature of the shift unit 8 is higher than a predetermined temperature optimum for the shift reaction, the control device 35 controls the flow rate regulator 3 to increase the amount of water supplied from the flow rate regulator 3. For example, the control device 35 increases the supply amount of water by increasing the output of the pump or further opening the on-off valve. As a result, the amount of water supplied to the second water evaporation unit 6 increases, and thus the amount of heat of the reformed gas recovered by the second water evaporation unit 6 increases. Therefore, the reformed gas having a smaller amount of heat that is cooled and held is supplied to the shift section 8, thereby suppressing the temperature rise of the shift section 8.

  Such evaporation of the water in the second water evaporation section 6 is pool boiling heated from below, so that bumping can be prevented, and therefore occurrence of pressure fluctuation in the apparatus can be prevented. . For this reason, as described above, it is possible to generate the reformed gas stably in the reforming unit 7 in particular. Further, it is possible to prevent metal ions dissolved in water or the like from being scattered due to bumping and intruding into the reforming unit 7, the metamorphic unit 8, and the like. For example, when the above metal ions enter the reforming part 7 or the metamorphic part 8 due to bumping, the metal ions are adsorbed on the catalyst of these parts to deactivate the catalytic activity, so that the durability of the apparatus is deteriorated. cause. On the other hand, in this Embodiment, since bumping is prevented, the scattering of the metal ion contained in water can be prevented and durability improves.

  Further, as described above, since the amount of water supplied from the flow rate regulator 3 is as small as 1/5 or less of the amount of water supplied from the water supply unit 1, the second water evaporation unit 6 The pressure of the second water vapor generated in step 1 is slightly smaller than the pressure of the first water vapor generated in the first water evaporation unit 5. Therefore, the second steam hardly affects the pressure ratio between the raw material gas supplied to the reforming unit 7 and the steam. Therefore, even if the amount of the second water vapor generated is changed by adjusting the amount of water supplied to the second water evaporation unit 6 to control the temperature of the shift unit 8, the reforming unit 7 can stably reform. The reaction can be performed.

  The second water vapor generated in the second water evaporation unit 6 in this way moves along the horizontal wall 103 in the second water vapor flow path 30 and then flows downward along the vertical wall 102 in the axial direction. Then, it enters the downstream flow path 11C of the reforming raw material flow path 11, moves along the horizontal wall 103 together with the mixed raw material gas that has moved in the downstream flow path 11B, and is supplied to the reforming unit 7. . In this way, the second water vapor channel 30 is adjacent to the post-transformation gas channel 13 via the horizontal wall 103 and the vertical wall 102 in the process of flowing the second water vapor through the second water vapor channel 30. Therefore, heat is transferred from the transformed gas to the second water vapor, and heat recovery is performed.

  As is clear from the above description and FIG. 2, also in the present embodiment, the water output from the water supply unit 1 branches in the middle of the water path in the same manner as in the first embodiment, and the first water evaporates. The flow rate is set to a predetermined S / C value required by the reforming unit 7 based on the value detected by the flow meter 2. The water supply unit 1 can be controlled. Therefore, in order to maintain the temperature detected by the temperature sensor 12 of the transformation unit 8 at a predetermined temperature, even if the flow rate of water supplied to the second water evaporation unit 6 by the flow rate adjustment unit 3 varies, the predetermined S / C Water vapor can be supplied from the first evaporation unit and the second evaporation unit to the reforming unit 7 while maintaining the value, and the same effect as in the first embodiment can be obtained.

In addition, when the water supplied from the flow controller 3 cannot be evaporated by the second water evaporation unit 6, the water moves in the second water vapor channel 30, and further the reforming raw material channel 11. It moves in the downstream flow path 11B and reaches the bottom of this flow path, that is, the first water evaporation section 5. Thus, the water that has reached the first water evaporation unit 5 evaporates in the first water evaporation unit 5 in the same manner as the water supplied from the water supply unit 1 described above. And the obtained water vapor | steam is supplied to the modification part 7 through the downstream flow paths 11B and 11C. As described above, even when the water cannot be completely evaporated in the second water evaporation unit 6, the water is not directly supplied to the reforming unit 7. Production efficiency does not decrease. Further, in this case, heat is recovered from the reformed gas also by the water that does not evaporate in the second water evaporation unit 6 and flows through.

  The CO concentration in the post-transformation gas obtained by the shift reaction is reduced to 1/5 to 1/50 of the CO concentration in the reformed gas according to the temperature of the shift reaction. However, in order to use it as fuel gas in the fuel cell 10, it is necessary to reduce the CO concentration to 10 ppm or less.

  For this reason, in the hydrogen generator used in the fuel cell power generation system, the transformed gas is further supplied to a purification unit (not shown) disposed downstream of the transformation unit 8 and processed. In the fuel cell power generation system, the hydrogen-based gas obtained by the hydrogen generator 150 is supplied to the fuel electrode of the fuel cell 10 as fuel gas. In the fuel cell 10, power generation is performed using a reaction between the fuel gas supplied to the fuel electrode and the oxygen gas supplied to the oxygen electrode.

  In the hydrogen generator of the present embodiment, the heat of the reformed gas supplied to the shift conversion unit 8 is recovered using the water supplied to the second water evaporation unit 6, so that the fuel offgas, combustion air, or Rather than heat exchange between gases, such as when heat exchange is performed between the combustion gas and the reformed gas, or when heat exchange is performed between the raw material gas for reforming reaction or steam and the reformed gas. The heat exchange rate between the liquid water and the gas reformed gas is increased, and the amount of recovered heat is increased. Therefore, the thermal efficiency is improved as a whole apparatus.

  Further, since the temperature adjustment of the transformation section 8 is performed by controlling an element independent of the influence of other parts of the apparatus, that is, the amount of water supplied from the flow rate regulator 3, as in the conventional case. The temperature of the transformation section 8 is not affected by the state change of the other parts of the apparatus. In particular, even if the load of the hydrogen generation amount in the reforming unit 7 changes, an element that causes a change in state with the change of the hydrogen generation load as in the past (specifically, fuel offgas, combustion air, As compared with the case where the temperature control of the metamorphic portion 8 is performed using a combustion gas or the like, it is possible to realize better controllability.

  Thus, in the fuel cell power generation system provided with the hydrogen generator in which the efficiency of heat recovery is improved and the temperature controllability of the shift section 8 is improved, the thermal efficiency of the entire system is improved and high energy efficiency is realized. And a highly durable system can be realized.

  In the above description, the reforming unit 7 has a configuration in which a platinum group metal is supported on a metal oxide carrier that is formed into a granular shape as described above. There may be. For example, according to the shape of the modified portion 7, a film-like metal oxide formed on a honeycomb substrate such as ceramic or metal is used as a carrier, and a platinum group metal is dispersed on the carrier. May be.

  In the above description, the metamorphic portion 8 has a configuration in which a platinum group metal is dispersedly supported on a film-like metal oxide support formed on a ceramic honeycomb substrate. Other than this may be used. For example, the base material may be a structure composed of a thin metal plate such as stainless steel, and a platinum group metal is supported on a metal oxide support that is formed into a granular shape according to the shape of the metamorphic portion 8. The structure filled with may be sufficient. Furthermore, a base metal such as a Cu—Zn-based material may be used as the shift catalyst for the shift unit 8 in addition to the platinum group metal.

Here, when the platinum group metal is used as the shift catalyst of the shift section 8 as described above, the catalyst has higher heat resistance than when the base metal is used as the catalyst. It becomes possible to make it higher. Thus, in the transformation part 8 which has high heat resistance, a margin arises in control of the supply amount of the water from the flow volume regulator 3, and a margin arises in the fluctuation range of a supply amount. On the other hand, when the base metal is used as the shift catalyst, these metals have lower heat resistance than the platinum group metal, and thus the usable temperature range is narrow. However, in the present embodiment, the shift portion 8 is good. Since temperature controllability is realized, the effect of the present embodiment is effectively exhibited.

  In the above, the second water vapor generated in the second water evaporation unit 6 is mixed with the first water vapor generated in the first water evaporation unit 5, and reformed via the common reforming material flow path 11C. As a modification of the present embodiment, the first water vapor generated by the first water evaporation unit 5 and the second water vapor generated by the second water evaporation unit 6 are supplied as a modification of the present embodiment. The configuration may be such that the reforming unit 7 is supplied through separate flow paths.

  The hydrogen generator according to the present invention has an effect that the S / C in the reforming section is stabilized and the dew point of the reformed gas is stabilized, and the hydrogen generator and the household fuel cell power generation equipped with the hydrogen generator are provided. Useful as a system.

Schematic diagram of a hydrogen generator and a fuel cell system in Embodiment 1 of the present invention Schematic diagram of hydrogen generator and fuel cell system in Embodiment 2 of the present invention Schematic diagram of conventional hydrogen generator and fuel cell system

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water supply part 2 Flowmeter 3 Flow controller 5 1st water evaporation part 6 2nd water evaporation part 7 Reformation part 8 Transformation part 9 Oxidant supply part 10 Fuel cell 20 Heating part 12 Temperature detector 23 1st water supply Unit 24 First flow meter 25 Second water supply unit 26 Second flow meter

Claims (4)

In order to generate the steam using a reforming unit that generates reformed gas containing hydrogen by a reforming reaction using steam and a raw material, a heating unit that heats the reforming unit, and combustion exhaust gas of the heating unit A first water evaporation section, a shift section that converts carbon monoxide in the reformed gas into carbon dioxide by a shift reaction, and steam that is configured to exchange heat with the shift section and that uses heat of the shift section. A second water evaporation section to be generated, a temperature detection section for detecting the temperature of the shift section, a water supply section for supplying water to the first water evaporation section and the second water evaporation section, and an output from the water supply section And a branch part for supplying water to each of the first water evaporation part and the second water evaporation part on a water path through which the water is circulated,
A flow meter that measures the flow rate of water in the water path between the branch part and the water supply part, and a flow rate adjustment that adjusts the flow rate of water in the water path between the branch part and the second water evaporation part. And the flow rate adjusting unit adjusts the flow rate of water so that the temperature detected by the temperature detector by the heat exchange becomes a predetermined temperature. Based on the value of the water flow meter, the water supply unit so as to maintain the total amount of the water amount X supplied to the first water evaporation unit and the water amount Y supplied to the second water evaporation unit at a predetermined value. 2. The hydrogen generator according to claim 1, wherein the hydrogen generator is controlled. 2. The hydrogen generator according to claim 1, wherein a pump is used instead of the water supply unit and the flow meter, and the flow rate adjusting unit is a pump. A fuel cell system comprising the hydrogen generator according to claim 1 and a fuel cell that generates electric power using hydrogen and an oxidant gas supplied from the hydrogen generator.

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