JP2005108651A - Reforming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the thermal efficiency of a reforming device by supplying reformed gas with a constant carbon monoxide concentration to a carbon monoxide purifying part. <P>SOLUTION: The reforming device 20 is composed of a reforming part 60 producing and leading out reformed gas from fuel, a CO shift part 80 lowering a carbon monoxide in the reformed gas supplied by the reforming part 60, and a CO purifying part 40 further lowering the carbon monoxide in the reformed gas supplied from the CO shift part 80. The CO shift part 80 has a heat exchanger 91 to which 91 a bypass tube 94a branched from an air supply tube 93 connected to an air supply source is connected, and the bypass tube 94a is provided with an electromagnetic valve 92. By switching the control of the electromagnetic valve 92, the temperature of the CO shift part 80 comes within a given range, and a carbon monoxide concentration in the reformed gas led out of the CO shift part 80 comes within a given range. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a reforming apparatus that generates a reformed gas from supplied fuel gas and water vapor and supplies the reformed gas to a fuel cell.

  The reformer generates a so-called hydrogen-rich reformed gas from the supplied fuel (for example, a hydrocarbon fuel such as natural gas, LP gas, kerosene) and steam and supplies the reformed gas to the fuel cell. is there. The fuel cell generates power by a chemical reaction between supplied hydrogen and oxygen. The reformer includes a reforming unit 102 that generates and derives a reformed gas from a mixed gas of supplied fuel and water vapor, and carbon monoxide in the reformed gas supplied from the reforming unit 102. A carbon monoxide shift reaction section (consisting of a high temperature shift section 106 and a low temperature shift section 110) to be reduced, and carbon monoxide in the reformed gas supplied from the carbon monoxide shift reaction section is further reduced to a fuel cell. What is comprised from the carbon monoxide purification | cleaning part (CO purification | cleaning part) 112 to supply is known (patent document 1).

In such a reformer, the concentration of carbon monoxide in the reformed gas derived from the carbon monoxide shift reaction section is not constant because it depends on the order. Therefore, in the CO purification unit 112, the carbon monoxide concentration (CO concentration) in the reformed gas (fuel gas) that is finally supplied to the anode 116 of the fuel cell 114 is equal to or less than the allowable concentration (for example, 5 ppm). As described above, the amount of the oxidizing gas blown into the CO purification unit 112 by the air pump 130 is adjusted.
Japanese Unexamined Patent Publication No. 2003-151599 (pages 7-9, FIG. 1)

In the above-described reformer, when the carbon monoxide concentration in the reformed gas supplied to the CO purification unit 112 is high, a large amount of air, that is, oxygen must be introduced to reduce the carbon monoxide concentration. However, since the reactions shown in Chemical Formulas 1 and 2 below occur in the CO purification unit 112, the input oxygen also reacts with hydrogen in the reformed gas. As a result, not only the carbon monoxide concentration in the reformed gas is reduced, but also the hydrogen concentration is reduced, which causes a problem that the thermal efficiency of the reformer is lowered.
(Chemical formula 1)
CO + 1 / 2O ₂ → CO ₂
(Chemical formula 2)
H ₂ + 1 / 2O ₂ → H ₂ O

  The present invention has been made to solve the above-described problems, and is to improve the thermal efficiency of the reformer by supplying a reformed gas having a constant carbon monoxide concentration to the carbon monoxide purifier. Objective.

  In order to solve the above problems, the structural feature of the invention according to claim 1 is that a reforming unit that generates and derives a reformed gas from a mixed gas of supplied fuel and water vapor, and the reforming unit A carbon monoxide shift reaction unit that reduces carbon monoxide in the reformed gas supplied from the fuel, and further reduces the carbon monoxide in the reformed gas supplied from the carbon monoxide shift reaction unit to a fuel cell. In the reformer configured with the carbon monoxide purification unit to be supplied, a heat exchanger is provided in the carbon monoxide shift reaction unit to perform heat exchange with the carbon monoxide shift reaction unit to lower the temperature. Refrigerant supply means for supplying refrigerant to the exchanger, refrigerant adjustment means for adjusting the supply amount of refrigerant provided in the refrigerant supply means, temperature detection means for detecting the temperature in the carbon monoxide shift reaction section, and temperature detection means Based on the temperature detected by And a control means for adjusting the supply amount of the refrigerant by controlling the refrigerant adjustment means, and adjusting the supply amount of the refrigerant by the control means so that the temperature detected by the temperature detection means falls within a predetermined range. In other words, the carbon monoxide concentration in the reformed gas that is correlated with the temperature in the carbon monoxide shift reaction section and derived from the carbon monoxide shift reaction section is controlled to be within a predetermined range.

  The structural feature of the invention according to claim 2 is that, in claim 1, the temperature detection means detects the temperature in the vicinity of the reformed gas outlet for deriving the reformed gas provided in the carbon monoxide shift reaction section, By adjusting the refrigerant supply amount by the control means so that the temperature detected by the temperature detection means is within a predetermined range, there is a correlation with the temperature near the reformed gas outlet, and the carbon monoxide shift This is to control the carbon monoxide concentration in the reformed gas derived from the reaction section so as to be within a predetermined range.

  The structural feature of the invention according to claim 3 is that, in claim 1 or claim 2, the liquid or gas supplied to the reformer as the refrigerant is employed.

  The structural feature of the invention according to claim 4 is the combustion gas according to any one of claims 1 to 3, wherein the reformed portion is heated by burning the supplied combustible fuel and combustion air. A combustion section that generates water, an evaporation section that heats the supplied water with combustion gas to generate water vapor and supplies it to the reforming section, and a reformed gas derived from the reforming section is cooled by a mixed gas and derived A cooling unit that further integrates the reforming unit, the cooling unit, and the carbon monoxide shift reaction unit to form an inner integrated structure, and the carbon monoxide purification unit and the evaporation unit are formed in a cylindrical shape and integrated. Forming the outer integrated structure, extrapolating the outer integrated structure to the inner integrated structure so that the carbon monoxide shift reaction part protrudes, and attaching the heat exchanger to the outer wall surface of the carbon monoxide shift reaction part It is.

  In the invention according to claim 1 configured as described above, the carbon monoxide concentration in the reformed gas derived from the carbon monoxide shift reaction unit is within a predetermined range, and the carbon monoxide concentration is constant. The reformed gas is supplied to the carbon monoxide purification section. Therefore, in the carbon monoxide purification unit, the carbon monoxide concentration can be reduced to a predetermined concentration without adding oxygen more than necessary, and the oxidation reaction of hydrogen in the reformed gas is not performed excessively. The hydrogen concentration can also be suppressed to the minimum necessary reduction. Thereby, since there is no useless consumption of hydrogen, it is possible to prevent the thermal efficiency of the reformer from being lowered.

  In the invention according to claim 2 configured as described above, the temperature in the vicinity of the reformed gas outlet of the carbon monoxide shift reaction unit is controlled so as to be within a predetermined range. When the temperature of the place is within a predetermined range, since the temperature of the reformed gas fluctuates until it reaches the reformed gas outlet, the temperature variation of the derived reformed gas is suppressed. The reformed gas is derived without the carbon monoxide concentration deviating from the predetermined range, and the reformed gas having a constant carbon monoxide concentration is reliably supplied to the carbon monoxide purification unit.

  In the invention according to claim 3 configured as described above, since the liquid or gas supplied to the reformer is adopted as the refrigerant of the heat exchanger, the liquid or gas conventionally supplied to the reformer is used. Since it can do, the high cost in the case of employ | adopting other than these liquids or gas as a refrigerant | coolant can be suppressed. In addition, since the refrigerant is heated and preheated by the carbon monoxide shift reaction unit, the heat radiation of the carbon monoxide shift reaction unit can be effectively used.

  In the invention according to claim 4 configured as described above, the reforming section, the cooling section, and the carbon monoxide shift reaction section, which are at a high temperature during steady operation of the reformer, have an evaporation section at a lower temperature than these components. Since it is surrounded by the carbon monoxide purification unit and the heat exchanger, the heat radiation from the reforming unit, the cooling unit, and the carbon monoxide shift reaction unit is absorbed by the evaporation unit, the carbon monoxide purification unit, and the heat exchanger. As a result, heat that has been released to the outside of the conventional system is used in the evaporation section, carbon monoxide purification section, and heat exchanger, and heat release from the reforming section, cooling section, and carbon monoxide shift reaction section is out of the system. Since the release is prevented, the thermal efficiency of the reformer can be improved.

a) First Embodiment A fuel cell system to which a first embodiment of a reformer according to the present invention is applied will be described below. FIG. 1 is a schematic view showing an outline of the fuel cell system, and FIG. 2 is an enlarged cross-sectional view showing a reformer.

  As shown in FIG. 1, the fuel cell system includes a fuel cell 10 and a reformer 20 that generates and supplies hydrogen gas necessary for the fuel cell 10. A reformed gas is supplied from the reformer 20 to the fuel electrode of the fuel cell 10, and air from the outside is supplied to the air electrode of the fuel cell 10. It reacts with oxygen gas in the air to generate electricity.

  The reformer 20 includes an outer integrated structure 21 formed by directly connecting the evaporation unit 30 and the carbon monoxide purification unit (hereinafter referred to as a CO purification unit) 40, a reforming unit 60, and a cooling unit 70. And a carbon monoxide shift reaction section (hereinafter referred to as a CO shift section) 80 and an inner integrated structure 22 that are integrated by directly connecting them. The outer integrated structure 21 is assembled and fixed to the base 15. The inner integrated structure 22 is disposed inside the outer integrated structure, and a locking portion 22a (described later) is placed on a receiving portion 21a (described later) of the outer integrated structure 21 at a joint portion thereof. One point is supported.

  The evaporation section 30 heats the supplied water with combustion gas to generate water vapor and supplies it to the reforming section 70 described later. As shown mainly in FIG. 2, the evaporation section 30 has a cylindrical shape (in this embodiment, It is formed in a cylindrical shape. The evaporator 30 is installed and fixed with the outer bottom plate 35 abutting on the base 15, and is disposed coaxially with a space facing the outside of the reformer 60.

  The evaporation section 30 is disposed between the outer cylinder 31, the inner cylinder 32 disposed coaxially with the space facing the reforming section 60 inside the outer cylinder 31, and both the cylinders 31, 32. And a cylindrical partition 33 that divides the space between the cylinders 31 and 32. An outer peripheral end of a top plate 34 formed in an annular shape is connected to the upper end of the outer cylinder 31. A cylindrical partition 33 is suspended from the lower surface of the top plate 34. As shown in FIG. 3, a plurality of (for example, two) fins 39 formed in a cylindrical shape are closely fitted to both the members 33 and 32 and are coaxially inserted between the cylindrical partition 33 and the inner cylinder 32. ing. The fins 39 are formed with wavy irregularities along the circumferential direction. A cylindrical body 39a is fitted between the fins 39.

  A plurality of through holes 34 a are formed in the top plate 34 along an annular portion between the cylindrical partition 33 and the outer cylinder 31, and these through holes 34 a are water outlets through which water is derived. The inner cylinder 32 is disposed with a space from the top plate 34, and is a combustion gas introduction port 32 a for introducing combustion gas between the upper end of the inner cylinder 32 and the top plate 34. An annular receiving portion 21 a is fixed to the top surface of the top plate 34. The receiving portion 21a is preferably a heat insulating material (for example, a ceramic material or a ceramic fiber material). Thereby, it is possible to prevent the heat of the combustion gas from escaping to the cooling unit 70.

  To the lower ends of the outer cylinder 31, the cylindrical partition 33, and the inner cylinder 32, the outer bottom plate 35, the annular partition 36, and the outer peripheral end of the inner bottom plate 37 formed in an annular shape are respectively connected. An outer cylinder 31, a cylindrical partition 33, and a short cylinder 38 shorter than the inner cylinder 32 are erected on the inner peripheral edge of the outer bottom plate 35. The inner peripheral end of the annular partition 36 and the inner bottom plate 37 is connected to the vertical center and upper end of the outer peripheral wall surface of the short cylinder 38, respectively. A water inlet 31 a for introducing water is provided at the lower part of the outer cylinder 31. The annular partition 36 is provided with a combustion gas outlet 36 a through which the combustion gas is led out through the outer bottom plate 35.

  In the evaporation unit 30 configured as described above, the water introduced from the water inlet 31a is circulated (passed) through the annular space formed between the outer cylinder 31 and the cylindrical partition 33, that is, the supplied water. ) Through the flowing water channel 30a to be led out from the water outlet (a plurality of through holes 34a). The combustion gas introduced from the combustion gas inlet 32a passes through the annular space formed between the cylindrical partition 33 and the inner cylinder 32, that is, the combustion gas flow path 30b through which the combustion gas supplied from the combustion section 50 passes. It passes through the combustion gas outlet 36a. And heat exchange is performed between water and combustion gas via the cylindrical partition 33, water is heated by combustion gas, and combustion gas falls in temperature.

  The CO purification unit 40 further reduces the carbon monoxide in the reformed gas supplied from the CO shift unit 80 and supplies it to the fuel cell 10. As shown mainly in FIG. In the form of a cylinder). The CO purification unit 40 is coaxially and integrally fixed to the top plate 34 of the evaporation unit 30, and is disposed coaxially with a space facing the cooling unit 70.

  The CO purification unit 40 has the same diameter as the outer cylinder 31 of the evaporation unit 30 and is disposed coaxially with a space facing the cooling unit 70 and coaxially inside the outer cylinder 41. An arranged inner cylinder 42 and a cylindrical partition 43 that is disposed between both cylinders 41 and 42 and divides a space between both cylinders 41 and 42 are provided. The lower ends of the outer cylinder 41 and the inner cylinder 42 are connected to the upper surface of the top plate 34 of the evaporation unit 30, and both the tubes 41 and 42 are erected on the top plate 34 of the evaporation unit 30. An outer peripheral edge and an inner peripheral edge of an annularly formed top plate 44 are connected to the upper ends of the outer cylinder 41 and the inner cylinder 42, respectively. The upper and lower ends of the cylindrical partition 43 are connected to inner peripheral edges of upper and lower annular partition plates 45 and 46 formed in an annular shape. The outer peripheral edges of the upper and lower annular partition plates 45 and 46 are connected to the inner peripheral wall surface of the outer cylinder 41.

  The through-hole 34 a provided in the top plate 34 of the evaporation unit 30 is a water outlet for deriving water (or water vapor) in the evaporation unit 30, but introduces water (or water vapor) in the CO purification unit 40. Water inlet. A lower portion of the outer cylinder 41 is provided with a reformed gas outlet 41a for leading out the reformed gas at a position above the connection portion of the lower annular partition plate 46, and an upper annular partition plate 45 is connected to the upper portion of the outer cylinder 41. A reformed gas inlet 41b for introducing the reformed gas is provided at a position below the part. The top plate 44 is provided with a water outlet 44a for leading out water (or water vapor).

  In the CO purification unit 40 configured in this manner, heated water (or water vapor) introduced from the water inlet 34a is a space formed between the cylindrical partition 43 and the inner cylinder 42, that is, supplied. The water (or water vapor) thus discharged passes through (passes through) the flowing water passage 40a and is led out from the water outlet 44a. The reformed gas introduced from the reformed gas inlet 41b is a space formed between the outer cylinder 41 and the cylindrical partition 43, that is, the reformed gas and air (oxidized air) supplied from the CO shift unit 80. Through the reformed gas flow path 40b through which the mixed gas passes. Then, heat exchange is performed between the water and the reformed gas through the cylindrical partition 43, the water is further heated by the reformed gas, and the temperature of the reformed gas drops. In the reformed gas channel 40b, carbon monoxide in the introduced mixed gas reacts with oxygen to become carbon dioxide. This reaction is promoted by a catalyst 40c (for example, a Ru or Pt catalyst) filled between the upper and lower annular partition plates 45 and 46. Thereby, the reformed gas is derived by further reducing the carbon monoxide concentration (10 ppm or less) by the oxidation reaction, and is supplied to the fuel electrode of the fuel cell 10.

  The combustion unit 50 generates combustion gas for heating the reforming unit 60, and is disposed coaxially with a space inside the evaporation unit 30 as mainly shown in FIG. The combustion unit 50 includes a burner body 51 and a burner combustion unit 52. The burner body 51 has a flange 51a formed at the center in the vertical direction. The flange 51a is attached and fixed to an annular flange 37a that protrudes inward from the inner peripheral end of the inner bottom plate 37 of the evaporation section 30. Thereby, the upper half of the burner main body 51 is inserted and attached to the inside of the evaporation part 30. A gas introduction port 51b for introducing combustion fuel, combustion air (combustion air) and off-gas is provided in the lower part of the burner body 51, and the introduced combustible fuel (combustion fuel or off-gas) is provided in the upper part of the burner body 51. ) Is provided as an igniting means. The burner combustion part 52 is formed in a cylindrical shape, is fitted on the upper part of the burner body 51, is inserted with a space in the recess 60a of the reforming part 60, and the opening of the burner combustion part 52 is reformed. It arrange | positions facing the bottom part (namely, inner side top plate 65) of the recessed part 60a of the part 60. FIG. In the burner combustion part 52, the combustion fuel or off-gas ignited by the ignition means burns. The burner combustion part 52 is formed of a heat-resistant heat insulating material (for example, a ceramic material or a ceramic fiber material).

  In the combustion section 50 configured as described above, the combustion fuel or off-gas introduced from the gas inlet 51 b is burned, and the combustion gas is led out from the open end of the burner combustion section 52. And this combustion gas is the annular flow path 56a formed between the burner combustion part 52 and the inner wall surface of the cylinder part of the reforming part 60, the outer wall surface of the cylinder part of the reforming part 60, and the heat insulation member 55 ( (Which will be described later) and an annular passage 56b communicating with the lower part of the annular passage 56a and led out to the combustion gas passage 30b of the evaporator 30.

  A heat insulating member 55 is disposed between the evaporation unit 30 and the reforming unit 60 so as to cover the inner wall surface of the evaporation unit 30, that is, the inner peripheral wall surface of the inner cylinder 32 of the evaporation unit 30 and the upper surface of the inner bottom plate 37. ing. The heat insulating member 55 is formed by integrally forming a cylindrical body 55a and an annular bottom plate 55b having an outer peripheral end connected to the lower end of the cylindrical body 55a. The inner peripheral end of the annular bottom plate 55b is in airtight contact with the lower end of the burner combustion section 52.

  The reforming unit 60 generates and derives a reformed gas from a mixed gas of fuel and water vapor supplied from the outside, and is mainly formed in a bottomed cylindrical shape as shown in FIG. The reforming unit 60 is disposed so that the cylindrical portion of the reforming unit 60 is inserted into the annular space between the burner combustion unit 52 of the combustion unit 50 and the cylindrical body 55 a of the heat insulating member 55 and is surrounded by the evaporation unit 30. Has been. The reforming unit 60 is integrally fixed to a bottom plate 73b of an annular manifold 73 of the cooling unit 70 described later.

  The cylinder portion of the reforming portion 60 is disposed between the outer cylinder 61, the inner cylinder 62 coaxially disposed inside the outer cylinder 61, and both the cylinders 61, 62. And a cylindrical inner partition 63 that partitions the space. The outer cylinder 61 and the partition 63 are suspended from the bottom plate 73 b of the annular manifold 73 of the cooling unit 70. The through hole 73b1 formed in the bottom plate 73b of the cooling unit 70 is a mixed gas inlet for introducing a mixed gas of fuel and water vapor. An outer peripheral end of an annular bottom plate 64 is connected to the lower end of the outer cylinder 61. An inner cylinder 62 is erected on the inner peripheral edge of the bottom plate 64. The upper end opening of the inner cylinder 62 is covered with an inner top plate 65. The lower end of the middle partition 63 is arranged with a space from the bottom plate 64. An annular pressing plate 66 is fitted between the outer cylinder 61 and the inner partition 63, and an annular partition plate 67 having an opening 67 a formed in the center is fitted to the inner cylinder 62. The opening 67 a is covered with a filter 68. The opening 67a is a reformed gas outlet for leading out the reformed gas.

  The reforming portion 60 between the annular pressing plate 66 and the annular partition plate 67 is filled with a catalyst 60a (for example, Ru or Ni-based catalyst), and the fuel introduced from the mixed gas introduction port 73b1 A gas mixture with water vapor is reacted and reformed by the catalyst 60a to generate hydrogen gas and carbon monoxide gas (so-called water vapor reforming reaction). At the same time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide generated in the steam reforming reaction reacts with steam to transform into hydrogen gas and carbon dioxide. These generated gases (so-called reformed gas) are led out to the cooling unit 70 through the reformed gas outlet 67a.

  The cooling unit 70 derives the reformed gas derived from the reforming unit 60 by lowering the temperature using a mixed gas of fuel and water vapor, and is fixed coaxially with the reforming unit 60 as shown mainly in FIG. Has been. The cooling unit 70 is supported by placing a lower peripheral edge of an annular manifold 73 serving as a locking unit 22 a on a receiving unit 21 a provided in the evaporation unit 30. The cooling unit 70 is arranged so as to face the inside of the CO purification unit 40 with a space therebetween, that is, arranged so as to be surrounded by the CO purification unit 40.

  The cooling unit 70 includes a cylindrical housing 71. The outer peripheral ends of the annular manifolds 72 and 73 are connected to the upper end and the lower end of the cylindrical housing 71, respectively. The annular manifold 72 includes an annular top plate 72a and a bottom plate 72b, an outer cylinder 72c having upper and lower ends connected to outer peripheral ends of the top plate 72a and the bottom plate 72b, and inner peripheral ends of the top plate 72a and the bottom plate 72b. And an inner cylinder 72d having upper and lower ends connected to each other. The top plate 72a is provided with a mixed gas inlet 72a1 for introducing a mixed gas of fuel and water vapor. The bottom plate 72b is provided with a through hole 72b1 communicating with a manifold 76 described later. Similarly to the annular manifold 72, the annular manifold 73 is also composed of a top plate 73a and a bottom plate 73b, an outer cylinder 73c, and an inner cylinder 73d formed in an annular shape. The top plate 73a is provided with a through hole 73a1 communicating with a manifold 75 described later. A plurality of through holes 73b1 are formed in the bottom plate 73b along an annular portion between the outer cylinder 61 of the reforming portion 60 and the partition 63.

  The upper and lower ends of the inner cylinder 74 having a rectangular cross section are connected to the peripheral edges of the openings 72e and 73e of the annular manifolds 72 and 73, respectively. A pair of manifolds 75 and 76 formed in a vertically long box shape are provided on the outer wall surfaces of the pair of side walls facing each other of the inner cylinder 74. The upper and lower ends of both manifolds 75 and 76 are fixed to the annular manifolds 72 and 73, respectively. In the inner cylinder 74, a plurality of heat exchange pipes 77 communicating with both the manifolds 75 and 76 are provided. On the outer periphery of the heat exchange pipe 77, fins 77a are provided for increasing the surface area and improving the heat transfer effect.

  In the cooling unit 70 configured as described above, the mixed gas of fuel and water vapor introduced from the mixed gas introduction port 72a1 passes through the annular manifold 72, the through hole 72b1, the manifold 76, the heat exchange pipe 77, the manifold 75, and the through hole. It is led out to the reforming section 60 through 73a1, the annular manifold 73, and the through hole 73b1. On the other hand, the reformed gas introduced from the opening 73 e of the annular manifold 73 that is the reformed gas introduction port is led out to the CO shift unit 80 through the inner cylinder 74 and the opening 72 e of the annular manifold 72. Then, heat exchange is performed between the mixed gas and the reformed gas via the heat exchange pipe 77, the mixed gas is heated by the reformed gas, and the temperature of the reformed gas drops.

  The CO shift unit 80 reduces carbon monoxide in the reformed gas supplied from the cooling unit 70. As shown mainly in FIG. 2, the CO shift unit 80 is coaxially fixed on the cooling unit 70, and the CO shift unit 80 is provided so as to protrude from the outer integrated structure 21. The CO shift unit 80 includes an outer cylinder 81 and an inner cylinder 82 arranged coaxially with the outer cylinder 81. An outer peripheral edge and an inner peripheral edge of a bottom plate 83 formed in an annular shape are integrally attached and fixed to lower end edges of the outer cylinder 81 and the inner cylinder 82. An outer peripheral edge of a top plate 84 formed in a disc shape is integrally attached and fixed to the upper end edge of the outer cylinder 81. A gap is formed between the top plate 84 and the upper end of the inner cylinder 82. A reformed gas outlet 81 a through which the reformed gas is led out is provided at the lower outer periphery of the outer cylinder 81. The downward extension 82 a of the inner cylinder 82 is integrally attached and fixed on the top plate 72 a of the annular manifold 72 of the cooling unit 70. The extension part 82 a is a reformed gas inlet for introducing the reformed gas derived from the cooling part 70.

  A first support member 85 that is formed in a disk shape and has a large number of holes is attached to the lower portion of the inner cylinder 82 of the CO shift portion 80, and the catalyst 80 a filled in the inner cylinder 82 by the first support member 85. (For example, Cu and Zn-based catalysts) are supported. In addition, a second support member 86 formed in an annular disk and having a large number of holes is attached to the lower portion between the outer cylinder 81 and the inner cylinder 82 at a distance from the bottom plate 83. A catalyst 80a filled between the outer cylinder 81 and the inner cylinder 82 is supported.

  A temperature sensor 80a1 for detecting the temperature in the vicinity of the reformed gas outlet 81a is provided in the catalyst 80a. The detection result of the temperature sensor 80a1 is transmitted to the control device 95 described later. The temperature sensor 80a1 can be provided at any location within the catalyst 80a between the outer cylinder 81 and the inner cylinder 82.

  In the CO shift unit 80 configured as described above, the reformed gas introduced from the reformed gas introduction port 82a is reformed through the inner cylinder 82 and the space between the inner cylinder 82 and the outer cylinder 81. Derived from the gas outlet 81a. At this time, as shown in Chemical Formula 3 below, a so-called carbon monoxide shift reaction occurs in which carbon monoxide and water vapor contained in the supplied reformed gas react with the catalyst 80a to be converted into hydrogen gas and carbon dioxide gas. ing.

(Chemical formula 3)
CO + H ₂ O⇔H ₂ + CO ₂ + Q

  This reaction is a reversible reaction and reaches a predetermined equilibrium state depending on the temperature of the catalyst. That is, when the temperature is lowered in a certain equilibrium state, the reaction of Chemical Formula 3 proceeds to the right so as not to lower the temperature, but the equilibrium state is reached at the lowered temperature. At this time, since the reaction of Chemical Formula 3 proceeds to the right, the carbon monoxide concentration decreases. Further, when the temperature is raised in a certain equilibrium state, the reaction of Chemical Formula 3 proceeds to the left so as not to raise the temperature, but the equilibrium state is reached at the raised temperature. At this time, since the reaction of Chemical Formula 3 proceeds to the left, the carbon monoxide concentration increases. Therefore, there is a correlation between the temperature of the catalyst 80a, that is, the temperature in the CO shift unit 80, and the carbon monoxide concentration in the reformed gas in the CO shift unit 80. In particular, a graph showing the correlation between the temperature near the reformed gas outlet 81a and the concentration of carbon monoxide in the reformed gas passing near the reformed gas outlet 81a is shown in FIG. This correlation is uniquely determined when the steam-carbon ratio (S / C), which is the ratio of water to fuel supplied to the reformer 20, is determined. FIG. 5 is a graph showing the correlation when the S / C ratio is 2.75, 3.00, or 3.25.

  On the top plate 84 of the CO shift unit 80, a heat exchanger 91 that performs heat exchange with the CO shift unit 80 to lower the temperature of the CO shift unit 80 is provided in contact therewith. As shown in FIG. 2, the heat exchanger 91 is divided into a housing 91a, a refrigerant introduction port 91b for introducing a refrigerant into the housing 91a, a refrigerant outlet 91c for extracting the refrigerant from the housing 91a, and a housing 91a. Thus, a partition 91e is formed to form a coolant channel 91d through which the coolant flows. The refrigerant flow path 91d communicates with the refrigerant introduction port 91b and the refrigerant outlet port 91c, and is disposed by being folded back within the housing 91a.

  As shown in FIG. 1, a bypass pipe 94a branched from an air supply pipe 93 that connects an air supply source (not shown) and the burner body of the combustion unit 50 is connected to the refrigerant introduction port 91b. A bypass pipe 94b that joins the air supply pipe 93 again is connected to the refrigerant outlet 91c. The bypass pipe 94a is provided with an electromagnetic valve 92 as refrigerant adjusting means for opening and closing the bypass pipe 94a. The electromagnetic valve 92 is opened and closed by a control device 95 to adjust the supply amount of refrigerant. Thereby, when the electromagnetic valve 92 is open, a part of the air supplied from the air supply source is supplied to the heat exchanger 91 through the bypass pipe 94a, and again to the air supply pipe 93 through the bypass pipe 94b. Merged and supplied to the burner body. The electromagnetic valve 92 is not limited to an on-off valve, and may be a flow rate adjusting valve. Also in this case, the electromagnetic valve 92 is controlled by a command from the control device 95 to adjust the supply amount of the refrigerant.

  As shown in FIG. 5, a temperature sensor 80a1, an electromagnetic valve 92, and a switching device 90 (described later) are connected to the control device 95. The control device 95 includes a microcomputer (not shown), and the microcomputer includes an input / output interface, a CPU, a RAM, and a ROM (all not shown) connected through a bus. The CPU executes a program corresponding to the flowchart of FIG. 6, adjusts the refrigerant supply amount based on the input temperature of the CO shift unit 80, and controls the temperature within a predetermined range. Is for storing the program, and the RAM is for temporarily storing calculation values relating to control.

  The temperature control of the CO shift unit 80 of the reformer configured as described above will be described with reference to the flowchart of FIG. When the reformer 20 is activated, the control device 95 executes a program corresponding to the above flowchart every predetermined short time. The control device 95 detects the temperature T of the CO shift unit 80 at step 102 every time execution of the program is started at step 100 in FIG. Then, the control device 95 controls the opening and closing of the electromagnetic valve 92 based on the detected temperature T to adjust the refrigerant supply amount. Specifically, if the detected temperature T is equal to or higher than the upper limit temperature Thigh (for example, 220 ° C.), the control device 95 opens the electromagnetic valve 92 and supplies refrigerant to the heat exchanger 91 to lower the temperature of the CO shift unit 80. (Steps 104 and 106). If the detected temperature T is lower than the lower limit temperature Tlow (for example, 200 ° C.), the control device 95 closes the electromagnetic valve 92 and stops the supply of the refrigerant to the heat exchanger 91 to raise the temperature of the CO shift unit 80. (Steps 104, 110, 112). As a result, the temperature of the CO shift unit 80 falls within a predetermined range (for example, 200 to 220 ° C.), and the concentration of carbon monoxide in the reformed gas derived from the CO shift unit 80 correlated with this temperature is within the predetermined range. (For example, 0.3 to 0.4%).

  During steady operation of the reformer configured as described above, as shown in FIG. 1, the water supplied to the evaporation unit 30 is heated by the combustion gas flowing in the combustion gas passage 30b in the flowing water passage 30a, and the CO 2 is supplied. It is led out to the flowing water channel 40a of the purification unit 40. The water (or water vapor) supplied to the water flow path 40a of the CO purification unit 40 is heated by the reformed gas supplied from the CO shift unit 80 and flowing through the reformed gas flow path 40b in the water flow path 40a, and the cooling unit 70. To the manifold 76. At this time, fuel is mixed with water (or water vapor), and a mixed gas in which these are mixed is led to the manifold 76 of the cooling unit 70.

  In the cooling unit 70, while the introduced mixed gas reaches the annular manifold 73 as described above, it is heated and completely gasified by the reformed gas supplied from the reforming unit 60 and flowing in the inner cylinder 74. And led to the reforming unit 60. In the reforming unit 60, the introduced mixed gas is reformed to generate hydrogen gas and carbon monoxide gas. At the same time, a so-called carbon monoxide shift reaction occurs in which carbon monoxide generated in the steam reforming reaction reacts with steam to transform into hydrogen gas and carbon dioxide. These generated gases (so-called reformed gas) are led out to the inner cylinder 74 of the cooling unit 70. In the inner cylinder 74 of the cooling unit 70, the temperature of the reformed gas is lowered while passing through the inner cylinder 74 and is led to the CO shift unit 80.

  In the CO shift unit 80, the reformed gas supplied from the cooling unit 70 reduces the carbon monoxide contained in the reformed gas, and the concentration of the reformed gas reaches a predetermined range. To 40b. At this time, oxidation reaction air is mixed with the reformed gas, and a mixed gas in which these are mixed is led out to the reformed gas flow path 40b of the CO purification unit 40. In the reformed gas flow path 40 b of the CO purification unit 40, the mixed gas is derived by further reducing the carbon monoxide concentration by an oxidation reaction, and is supplied to the fuel electrode of the fuel cell 10.

  Further, a switching device 90 is provided between the CO purification unit 40 and the fuel cell 10, and the CO purification unit 40 communicates with the fuel cell 10 during steady operation, and a reformed gas having a high carbon monoxide concentration during start-up operation. In order to prevent the fuel cell 10 from being supplied to the fuel cell 10, the CO purification unit 40 is switched to communicate with the burner body 51 of the combustion unit 50. Thus, at the time of start-up operation, at least one of the combustion fuel from the outside or the reformed gas derived from the CO purification unit 40 is supplied to the burner body 51 and burned. The used hydrogen gas (off-gas) is supplied to the burner body 51 and burned.

  As can be understood from the above description, in this embodiment, the carbon monoxide concentration in the reformed gas derived from the CO shift unit 80 is within a predetermined range, and this carbon monoxide concentration is constant. A certain reformed gas is supplied to the CO purification unit 40. Therefore, in the CO purification unit 40, the carbon monoxide concentration can be reduced to a predetermined concentration (10 ppm or less) without introducing oxygen more than necessary, and an extra oxidation reaction of hydrogen in the reformed gas is also performed. Therefore, the hydrogen concentration can be suppressed to the minimum necessary level. Thereby, since there is no useless consumption of hydrogen, it is possible to prevent the thermal efficiency of the reformer 20 from being lowered.

  Further, in order to control the temperature in the vicinity of the reformed gas outlet 81a of the CO shift unit 80 to be within a predetermined range, when the temperature at a location away from the reformed gas outlet 81a is within the predetermined range, Compared to the fact that the gas temperature fluctuates before reaching the reformed gas outlet 81a, the temperature fluctuation of the derived reformed gas is suppressed, so that the carbon monoxide concentration is improved without deviating from the predetermined range. The quality gas is derived and the reformed gas having a constant carbon monoxide concentration is reliably supplied to the CO purification unit 40.

  Further, since the combustion air supplied to the reformer 20 is adopted as the refrigerant of the heat exchanger 91, the liquid or gas that has been conventionally supplied to the reformer can be used. High cost can be suppressed. Further, since the refrigerant is heated and preheated by the CO shift unit 40, the heat radiation of the CO shift unit 40 can be used effectively.

  Further, the reforming unit 60, the cooling unit 70, and the CO shift unit 80 that are at high temperatures during steady operation of the reforming apparatus 20 are converted by the evaporation unit 30, the CO purification unit 40, and the heat exchanger 91 that are at lower temperatures than these components. Since it is surrounded, the heat radiation from the reforming unit 60, the cooling unit 70 and the CO shift unit 80 is absorbed by the evaporation unit 30, the CO purification unit 40 and the heat exchanger 91. As a result, heat that has been released to the outside of the conventional system is used in the evaporation unit 30, the CO purification unit 40, and the heat exchanger 91, and the heat radiation from the reforming unit 60, the cooling unit 70, and the CO shift unit 80 is out of the system. Therefore, the thermal efficiency of the reformer 20 can be improved.

b) Second Embodiment Hereinafter, a fuel cell system to which a second embodiment of the reformer according to the present invention is applied will be described. FIG. 7 is a schematic diagram showing an outline of the fuel cell system. The same components as those of the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different portions are described.

  In the first embodiment described above, combustion air is employed as the refrigerant supplied to the heat exchanger 91, but instead of this, fuel may be employed as the refrigerant. In this case, a bypass pipe 97a branched from a fuel supply pipe 96 that connects a fuel supply source (not shown) and the cooling unit 70 is connected to the refrigerant introduction port 91b. A bypass pipe 97b that joins the fuel supply pipe 96 again is connected to the refrigerant outlet 91c. The bypass pipe 97a is provided with an electromagnetic valve 92 that opens and closes the bypass pipe 97a. The electromagnetic valve 92 is opened and closed by a control device 95 to adjust the amount of refrigerant supplied. Thereby, when the solenoid valve 92 is open, a part of the fuel supplied from the fuel supply source is supplied to the heat exchanger 91 through the bypass pipe 97a, and again to the fuel supply pipe 96 through the bypass pipe 97b. It merges and is supplied to the cooling unit 70.

  Also by this, since the fuel supplied to the reformer 20 is adopted as the refrigerant of the heat exchanger 91, the liquid or gas that has been conventionally supplied to the reformer can be used. The high cost when adopting can be suppressed. Further, since the refrigerant is heated and preheated by the CO shift unit 40, the heat radiation of the CO shift unit 40 can be used effectively.

  In addition, you may employ | adopt the water supplied to a reformer as a refrigerant | coolant supplied to the heat exchanger 91. FIG.

  In each of the above-described embodiments, the heat exchanger 91 is provided on the upper surface of the CO shift unit 80. However, the heat exchanger 91 may be provided on a location other than the upper surface, for example, on the outer peripheral surface as long as it is an outer wall surface.

  Moreover, in each embodiment mentioned above, although the solenoid valve was employ | adopted as a refrigerant | coolant adjustment means, it may replace with this and may be made to employ | adopt a pump. In this case, the discharge amount of the pump may be controlled by a command from the control device 95.

1 is a schematic diagram showing an outline of a fuel cell system to which a first embodiment of a reformer according to the present invention is applied. It is an expanded sectional view of the reformer shown in FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. It is a figure which shows the correlation with the temperature in the CO shift part shown in FIG. 1, and a carbon monoxide density | concentration. It is a block diagram which shows the fuel cell system shown in FIG. 6 is a flowchart of a control program executed by the control device shown in FIG. It is a schematic diagram which shows the outline | summary of the fuel cell system to which 2nd Embodiment by the reformer by this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 15 ... Base, 20 ... Reformer, 21 ... Outer integrated structure, 21a, 22b ... Receiving part, 21b, 22a ... Locking part, 22 ... Inner integrated structure, 30 ... Evaporating part, 30a ... Flow channel, 30b ... Combustion gas flow path, 31 ... Outer cylinder, 31a ... Water inlet, 32 ... Inner cylinder, 32a ... Combustion gas inlet, 33 ... Cylindrical partition, 34 ... Top plate, 34a ... Through hole (Water outlet), 35 ... outer bottom plate, 36 ... annular partition, 36a ... combustion gas outlet, 37 ... inner bottom plate, 38 ... short tube, 39 ... corrugated fin, 40 ... carbon monoxide purification unit (CO purification unit) 40a ... Flow channel, 40b ... Reformed gas flow path, 40c ... Catalyst, 41 ... Outer cylinder, 41a ... Reformed gas outlet, 41b ... Reformed gas inlet, 42 ... Inner cylinder, 43 ... Cylindrical partition, 44 ... Top plate, 44a ... Water outlet, 45, 46 ... Upper and lower annular partition plates, 50 ... Combustion , 51 ... burner body, 51b ... gas inlet, 52 ... burner combustion part, 55 ... heat insulating member, 56a, 56b ... annular flow path, 60 ... reforming part, 60a ... catalyst, 60b ... recess, 61 ... outer cylinder, 62 ... Inner cylinder, 63 ... Middle partition, 64 ... Bottom plate, 65 ... Inner top plate, 66 ... Annular retainer plate, 67 ... Annular partition plate, 67a ... Opening, 70 ... Cooling unit, 71 ... Cylindrical housing, 72, 73 ... Annular manifold, 74 ... inner cylinder, 75, 76 ... manifold, 77 ... heat exchange pipe, 77a ... fins, 80 ... carbon monoxide shift reaction part (CO shift part), 80a ... catalyst, 80a1 ... temperature sensor, 81 ... outside Cylinder, 81a ... reformed gas outlet, 82 ... inner cylinder, 82a ... extension (reformed gas inlet), 83 ... bottom plate, 84 ... top plate, 90 ... switching device, 91 ... heat exchanger, 92 ... electromagnetic Valve, 93 ... Air supply pipe, 94 , 94b, 97a, 97b ... the bypass pipe, 96 ... fuel supply pipe.

Claims (4)

A reforming unit that generates and derives a reformed gas from a mixed gas of supplied fuel and steam, and a carbon monoxide shift reaction that reduces carbon monoxide in the reformed gas supplied from the reforming unit A carbon monoxide purifying unit that further reduces the carbon monoxide in the reformed gas supplied from the carbon monoxide shift reaction unit and supplies the carbon monoxide to the fuel cell.
The carbon monoxide shift reaction unit is provided with a heat exchanger that lowers the temperature by performing heat exchange with the carbon monoxide shift reaction unit,
Refrigerant supply means for supplying refrigerant to the heat exchanger; refrigerant adjustment means provided in the refrigerant supply means for adjusting the supply amount of the refrigerant;
Temperature detecting means for detecting the temperature in the carbon monoxide shift reaction section;
Control means for controlling the refrigerant adjustment means based on the temperature detected by the temperature detection means to adjust the supply amount of the refrigerant;
By adjusting the supply amount of the refrigerant by the control means so that the temperature detected by the temperature detection means is within a predetermined range, there is a correlation with the temperature in the carbon monoxide shift reaction section, and A reformer that controls the concentration of carbon monoxide in the reformed gas derived from the carbon monoxide shift reaction unit to be within a predetermined range.   2. The temperature detection unit according to claim 1, wherein the temperature detection unit detects a temperature in the vicinity of a reformed gas outlet port through which the reformed gas is provided in the carbon monoxide shift reaction unit, and detects the temperature detected by the temperature detection unit. By adjusting the supply amount of the refrigerant by the control means so as to be within a predetermined range, it is correlated with the temperature in the vicinity of the reformed gas outlet and is derived from the carbon monoxide shift reaction unit. A reformer that controls the concentration of carbon monoxide in the reformed gas to be within a predetermined range.   3. The reformer according to claim 1, wherein a liquid or a gas supplied to the reformer is used as the refrigerant. 4. The combustion part according to claim 1, wherein the supplied combustible fuel and combustion air are burned to generate a combustion gas for heating the reforming part, and the supplied water is An evaporation unit that is heated by the combustion gas to generate the water vapor and supplies the water vapor to the reforming unit; and a cooling unit that lowers the temperature of the reformed gas derived from the reforming unit and derives the mixed gas. The reforming unit, the cooling unit, and the carbon monoxide shift reaction unit are integrated to form an inner integrated structure, and the carbon monoxide purification unit and the evaporation unit are formed into a cylindrical shape and integrated to form an outer integrated structure. The outer integrated structure was extrapolated to the inner integrated structure so that the carbon monoxide shift reaction part protrudes, and the heat exchanger was attached to the outer wall surface of the carbon monoxide shift reaction part Reforming equipment characterized by .

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