JP2004196611A - Fuel reforming apparatus and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel reforming apparatus in which the flow rate of air supplied to a reformer can be controlled with high accuracy even when the supply pressure of air to the reformer is decreased. <P>SOLUTION: The fuel reforming apparatus is equipped with: a reforming part (13) which generates a hydrogen-rich reformed gas from the source fuel containing hydrogen; a plurality of reaction parts (15, 17, 18) disposed along the passage of the reformed gas guiding the reformed gas to an exit; a plurality of heat exchangers (14a, 16a, 18a) respectively disposed in the reaction parts; a heat medium supply means which supplies a heating medium to each heat exchanger; a bypassing means (BP) which can supply the heating medium from the heat exchanger (14a) of the first reaction part at high temperature in the plurality of reaction parts to the heat exchanger (18a, 16a) of the second reaction part at relatively lower temperature than the first reaction part; and a controlling means (50) which activates the bypassing means (BP) when the inner temperature of the second reaction part is lower than a specified temperature. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel reforming apparatus that reforms a raw fuel containing hydrogen into a hydrogen-rich fuel gas and supplies it to a fuel cell, and a fuel cell system including the same.
[0002]
[Prior art]
2. Description of the Related Art A fuel cell is a device that directly converts chemical energy of a fuel into electric energy without passing through mechanical energy or thermal energy, and can realize high energy efficiency. As a well-known form of a fuel cell, a pair of electrodes is arranged with an electrolyte layer interposed therebetween, and a fuel gas containing hydrogen is supplied to one electrode (anode side) and oxygen gas is supplied to the other electrode (a cathode side). Is supplied, and an electromotive force is obtained by utilizing an electrochemical reaction occurring at both electrodes. The following shows an equation representing an electrochemical reaction occurring in a fuel cell. Equation (1) represents the reaction at the anode, and equation (2) represents the reaction at the cathode. In the entire fuel cell, the reaction shown in equation (3) proceeds.
H_Two → 2H⁺+ 2e^-                   … (1)
(1/2) O_Two+ 2H⁺+ 2e^- → H_TwoO ... (2)
H_Two+ (1/2) O_Two → H_TwoO ... (3)
Fuel cells are classified according to the type of electrolyte used, operating temperature, and the like. Among these fuel cells, a polymer electrolyte fuel cell, a phosphoric acid fuel cell, a molten carbonate electrolyte fuel cell, and the like include a hydrogen-rich gas. Can be used as a fuel gas.
[0003]
Therefore, a fuel cell is combined with a reformer to reform hydrocarbon-based raw fuels such as methanol, ethanol, natural gas, LPG, gasoline, light oil, and DME (dimethyl ether) to produce gas containing high concentration of hydrogen. Then, the fuel is supplied to a fuel cell as fuel to constitute a power generation system. Such a configuration facilitates storage and handling of fuel, and is being developed as a drive system for a next-generation vehicle.
[0004]
Reformer, for example, when reforming methanol as a raw fuel, in the reforming section so-called steam oxidation method (Steam reforming), partial oxidation method (Partial oxidation reforming) and an autothermal method using these together ( Autothermal reforming) is used to generate hydrogen-rich fuel gas. Since carbon monoxide CO is generated during this hydrogen generation process, a reaction section is further provided after the reforming section, and various catalysts are arranged in the reaction section to convert carbon monoxide CO into carbon dioxide CO._TwoShift to and decrease. Various types of catalysts are considered to perform their functions sufficiently by being maintained at a reaction temperature corresponding to the catalyst. Further, a small amount of carbon monoxide remaining in the reformed gas is converted into carbon dioxide by a selective oxidation reaction or a shift reaction in the CO purification section of the reformer.
[0005]
For example, Japanese Patent Application Laid-Open No. H10-334935 discloses a fuel cell power generation system in which a hydrogen-rich gas is extracted from city gas by a reformer and used as fuel. In this example, a heat exchange coil is arranged in each reaction section to adjust the temperature of each reaction section of the reformer, and the amount of water flowing through each heat exchange coil is controlled to appropriately maintain the temperature of each reaction section. This aims to improve the operating efficiency of the fuel cell.
[0006]
[Patent Document 1]
JP-A-10-334935
[0007]
[Problems to be solved by the invention]
However, in particular, in the case of a fuel cell system mounted on a vehicle or the like, it is indispensable to shorten the startup time of the fuel cell system in order to be able to immediately start the vehicle from a stopped state. In order to start the fuel cell system, first, the reformer must be stably operated at a predetermined temperature to generate hydrogen-rich gas stably and supply it to the fuel cell. At this time, the refrigerant flowing through the cooling unit for maintaining the reaction unit including the catalyst unit and the like inside the reformer at a constant temperature hinders the temperature rise of the reaction unit (catalyst), thereby increasing the time required for startup, It causes the starting energy to increase.
[0008]
Therefore, an object of the present invention is to provide a fuel reforming apparatus in which the reaction section of the reformer reaches a predetermined operating temperature in a short time and the startup time is shortened.
[0009]
Another object of the present invention is to provide a fuel cell system in which the reaction section of the reformer reaches a predetermined operating temperature in a short time to shorten the startup time.
[0010]
[Means to solve the problem]
In order to achieve the above object, the fuel reforming apparatus of the present invention is provided along an evaporator for gasifying raw fuel and water and a reformed gas flow path for reforming gasified raw fuel and water. A plurality of reaction units, a plurality of heat exchangers provided in each of the reaction units, a heat medium supply means for supplying a heat transfer medium to each of the heat exchangers, and a first high-temperature reaction among the plurality of reaction units. Means for supplying a heat transfer medium from the heat exchanger of the second reaction section to the heat exchanger of the second reaction section having a relatively lower temperature, and the internal temperature of the second reaction section is reduced. And control means for operating the bypass means when the temperature is equal to or lower than a predetermined temperature.
[0011]
With this configuration, the temperature of the low-temperature reaction section can be raised for a short time, and the startup time of the fuel cell system can be shortened.
[0012]
Further, the reforming apparatus of the present invention includes an evaporating section for gasifying raw fuel and water, and a plurality of reaction sections provided along a reformed gas flow path for reforming gasified raw fuel and water. A plurality of heat exchangers provided in each of the reaction sections, a heat medium supply means for supplying a heat transfer medium to each of the heat exchangers, and a first reaction provided on the upstream side of the reformed gas flow path. Means for supplying a heat transfer medium from the heat exchanger of the second reaction section to the heat exchanger of the second reaction section provided on the downstream side, and the internal temperature of the second reaction section is equal to or lower than a predetermined temperature. And control means for operating the bypass means.
[0013]
By adopting such a configuration, it is possible to accelerate the temperature rise of the downstream reaction section where the temperature rise tends to be delayed due to the delay of heat propagation, and it is possible to shorten the startup time of the fuel cell system.
[0014]
Preferably, the bypass means supplies the heat transfer medium simultaneously or individually from the heat exchangers of the first reaction section to the heat exchangers of at least two second reaction sections. This makes it possible to raise the temperature of the low-temperature heat exchanger simultaneously or selectively.
[0015]
Preferably, the bypass means directly supplies the heat transfer medium from the heat exchanger of the first reaction section to the heat exchanger of the second reaction section. The direct connection reduces the heat propagation time.
[0016]
Preferably, any one of the plurality of reaction units includes a catalyst that generates a hydrogen-rich reformed gas from the gasified raw fuel and water, and the catalyst is set to the optimum catalyst temperature by the heat exchanger. . Thereby, the efficiency of hydrogen generation can be improved.
[0017]
Preferably, the other of the plurality of reaction units includes various catalysts for oxidizing carbon monoxide CO, and the heat exchanger sets an optimum temperature for the catalyst. Thereby, various catalysts are set to the appropriate temperatures in a short time.
[0018]
Preferably, the control means operates the bypass means when the apparatus is started. As a result, it becomes possible to activate the reformer of the fuel cell system whose temperature has decreased at the time of start-up in a short time.
[0019]
Preferably, the heat transfer medium is water, and the heated water is supplied to the evaporator through the heat exchanger. Thereby, the thermal efficiency is increased.
[0020]
Preferably, the difference between the flow rate of the water heated via the heat exchanger and supplied to the evaporator and the flow rate of the water required by the evaporator is compensated for by the supply of the bypass water. As a result, it is possible to achieve both the flow of water to the appropriate heat exchanger for temperature control and the supply of the required amount of reformed water.
[0021]
Further, a fuel cell system of the present invention includes the above-described fuel reformer and a fuel cell which generates electricity by receiving a supply of reformed gas from the fuel reformer.
[0022]
With this configuration, it is possible to provide a fuel cell system that can be started in a short time.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
The reformer includes a combustion section, an evaporation section, a reforming section, a reaction section, and a CO purification section. The combustion section supplies the heat source required by the reformer. The evaporator gasifies the raw fuel and water. The reforming section generates a reformed gas (hydrogen-rich gas) containing a large amount of hydrogen by a steam reforming reaction. The reaction section has a plurality of shift reaction sections on the downstream side of the reformed gas flow path in order to reduce carbon monoxide CO generated when hydrogen is generated in the reforming section. The CO purifier reduces a trace amount of carbon monoxide remaining in the reformed gas by a selective oxidation reaction. Note that a plurality of types of catalysts are used to promote a chemical reaction in each part. Here, the reforming section, the reaction section, and the CO purification section correspond to a plurality of reaction sections. The heat supplied from the combustion section to the reforming section is transmitted to the reforming section, the reaction section, and the CO purification section by the vaporized gas or the like, and increases the temperature of the catalyst unit disposed in each section. Although a plurality of types of catalysts are provided in the above-described reaction section and the like, these catalysts each have an appropriate temperature. Therefore, reforming water used for steam reforming for both temperature setting and heat recovery is used as a catalyst unit. As a cooling medium (heat transfer medium). For this reason, it takes time for each catalyst to reach the optimum temperature and supply reformed gas to the fuel cell.
[0025]
Therefore, in the embodiment of the present invention, when the fuel cell system is started, a heat transfer medium (refrigerant) heated by the heat exchanger that first becomes high in temperature among the plurality of heat exchangers in the reformer is used. It is used to heat the heat exchanger in the section. In addition, by changing the heat exchanger to which the heated heat transfer medium is supplied in accordance with the temperature state of each section of the reformer during startup, the temperature rise of each section (catalyst unit) of the reformer can be entirely reduced. Facilitate.
[0026]
(First embodiment)
FIG. 1 is an explanatory diagram schematically illustrating a fuel reforming apparatus of the present invention. FIG. 1 shows a reformer 10 and a cooling water supply system 30 of the fuel reformer 1. The reformer 10 is supplied with fuel from a raw fuel supply system (not shown) and oxidized air from an air supply system. These auxiliary systems will be described later in a fuel cell system.
[0027]
The reformer 10 generates a hydrogen-rich reformed gas from a raw fuel containing hydrogen atoms, and includes a combustion unit 11, an evaporation unit 12, a reforming unit 13, a cooling unit 14, a high-temperature shift reaction unit 15, The cooling unit 16, the low-temperature shift reaction unit 17, and the CO purification unit 18 are configured. As a raw fuel containing hydrogen atoms, methane (CH_Four), Ethane (C_TwoH₆), Propane (C_ThreeH₈), Butane (C_FourH_Ten), Gasoline, light oil, natural gas, methanol (CH_ThreeOH), ethanol (C_TwoH_FiveOH), DME (CH_ThreeOCH_Three), Acetone (CH_ThreeC (= O) CH_Three) Can be used, but the following example describes the case where methanol is used.
[0028]
The combustion unit 11 generates heat necessary for performing a methanol reforming reaction (endothermic reaction) by burning methanol or surplus hydrogen from a fuel cell (not shown), and is provided in the evaporating unit 12 and the reforming unit 13. To the heat exchanger.
[0029]
The evaporator 12 receives heat from the combustor 11 in the heat exchanger, and uses this heat to vaporize methanol and water supplied from a methanol tank and a water tank described later.
[0030]
The reforming section 13 is provided with an electric heater as a means for heating the inside in addition to a catalyst for reforming the reformed raw material vaporized in the evaporating section 12 to secure an appropriate reaction temperature. When the reformer 10 is in a steady state, the inside of the reforming section 13 can be maintained at a temperature suitable for the reforming reaction by the heater and the heat balance of the reforming reaction. The reforming unit 13 is filled with, for example, pellets formed of a Cu—Zn catalyst, which is a catalytic metal that promotes a reforming reaction, and receives a supply of sufficiently heated methanol and water vaporized gas. To cause a steam reforming reaction and a partial oxidation reforming reaction to generate a hydrogen-rich reformed gas.
[0031]
The steam reforming reaction is
CH_ThreeOH + H_TwoO → CO_Two+ 3H_Two-131 (kJ / mol) ... (4)
CH_ThreeOH → CO + 2H_Two                            … (5)
CO + H_TwoO → CO_Two+ H_Two                            … (6)
As shown.
[0032]
Further, in the reforming section 13, oxidized air (O_Two: 21%, N_Two: 79%) to generate hydrogen by a partial oxidation reforming reaction (not shown).
[0033]
The partial oxidation reforming reaction is
CH_ThreeOH + 1 / 2O_Two+ 1.9N_Two→ 2H_Two+ CO_Two+155 (kJ / mol) ... (7)
CH_ThreeOH + 3 / 2O_Two+ 5.7N_Two→ + CO_Two+ 2H_TwoO + 5.7N_Two    … (8)
2CH_ThreeOH + 2H_TwoO → 6H_Two+ 2CO_Two+ 2H_TwoO ... (9)
As shown.
[0034]
The reformed gas generated in the reforming section 13 contains a small amount of carbon monoxide. In order to reduce the function of the platinum catalyst used in the electrode of the fuel cell, a shift reaction unit that converts carbon monoxide into carbon dioxide by a shift reaction is provided downstream of the reforming unit 13. In the shift reaction section, a plurality of reaction sections are arranged to promote the oxidation of carbon monoxide in various operating states by using different types of catalysts. In the embodiment, a high-temperature shift reaction section 15 that exhibits a catalytic function at a high temperature and a low-temperature shift reaction section 17 that exhibits a catalytic function even at a low temperature are arranged. Further, a CO purifying unit 18 described later is arranged as a reaction unit that uses a selective oxidation reaction.
[0035]
For example, the operating temperature of the catalyst unit of the high-temperature shift reaction unit 15 is about 300 ° C. (first target temperature), and the operating temperature of the 17 catalyst units of the low-temperature shift reaction unit is about 200 ° C. (second target temperature). Is set. In order to perform such a temperature setting, the high temperature shift reaction unit 15 and the low temperature shift reaction unit 17 are provided with cooling units 14 and 16, respectively. The high-temperature shift reaction unit 15 and the low-temperature shift reaction unit 17 are provided with temperature sensors 15a and 17a for detecting the temperature of the catalyst unit, respectively. The cooling units 14 and 16 are constituted by, for example, heat exchangers 14a and 16a provided in the reformed gas channel or the catalyst unit. Cooling water is supplied to each heat exchanger from an external coolant supply source (not shown). For example, the cooling water 1 is supplied to the heat exchanger 14a from the outside, and the cooling water 2 is supplied to the heat exchanger 16a. By adjusting the flow rate of each cooling water, it is possible to control so that the temperature Tn detected by the temperature sensor of each reaction section becomes a desired temperature. This is performed by the control unit 50 described later.
[0036]
Although the concentration of carbon monoxide in the reformed gas decreases through the high-temperature shift reaction section 15 and the low-temperature shift reaction section 17, a small amount of carbon monoxide still remains. This is removed in the CO purifier 18 so that hydrogen is not reduced by the selective oxidation reaction. The selective oxidation reaction is
CO + 1 / 2O_Two→ CO_Two
As shown. In this case, a catalyst is used.
[0037]
In the CO purifying unit 18, a platinum catalyst, a ruthenium catalyst, a palladium catalyst, a gold catalyst, and an alloy catalyst using these are selected catalysts for carbon monoxide in order to oxidize carbon monoxide in preference to hydrogen in the reformed gas. A carrier supporting the above is filled in the catalyst unit. Then, oxidizing air is supplied from outside to convert carbon monoxide into carbon dioxide by a selective oxidation reaction. The CO purifier 18 is provided with a heat exchanger 18a to which the cooling water 3 is supplied to maintain the temperature T3 of the catalyst unit at an appropriate temperature, for example, 150 ° C. (third target temperature), and a temperature sensor for detecting the catalyst temperature. 18b. By adjusting the flow rate of the cooling water 3, the temperature T3 can be controlled to an appropriate temperature. This is performed by the control unit 50. The reformed gas whose carbon monoxide has been reduced through the high-temperature shift reaction unit 15, the low-temperature shift reaction unit 17, and the CO purification unit 18 is supplied to a fuel cell described later.
[0038]
Next, the cooling water supply system 30 will be described. The cooling water 1 is heated from a coolant supply source via the heat exchanger 14 a and supplied to the evaporator 12 via the on-off valve 31. The cooling water 1 can be supplied to the heat exchanger 18a of the CO purification unit 18 as the cooling water 3 via the on-off valve 32 and the bypass flow path BP. The cooling water 2 is heated through the heat exchanger 16a and supplied to the evaporating section 12. The cooling water 3 is heated through the heat exchanger 16a and supplied to the evaporating section 12. By using the heated cooling water as the reforming water supplied to the evaporator, the thermal efficiency is improved. In addition, bypass water can be supplied from the water tank to the evaporator 11 for supplying reformed water at the time of startup.
[0039]
Next, the supply control of the cooling water (heat transfer medium) by the control unit 50 at the time of starting the fuel cell system will be described with reference to FIG.
[0040]
When the start is commanded from the outside, the control unit 50
(a) The on-off valve 31 is closed, and the on-off valve 32 is opened. The supply of the cooling water 1 to 3 is stopped.
(b) Fuel, such as methanol, oxidized air, and surplus hydrogen of a fuel cell, is supplied to the combustion unit 11 to ignite and start the burner to generate high-temperature combustion gas. This combustion gas is supplied to the heat exchanger of the evaporator 12, and generates a high-temperature gas such as air. This high-temperature gas is guided to the CO purification unit 18 downstream along the flow path of the reforming unit 13 to increase the temperature of the flow path. Note that the high-temperature combustion gas can be guided to the heat pipe of the reforming section by an exhaust gas pipe, and heat exchange can be performed to increase the temperature of the catalyst unit of the reforming section. In addition, the catalyst unit such as the reforming unit 13 may be operated to raise the temperature of the catalyst unit to a predetermined temperature.
(c) The control unit 50 monitors the output temperature T1 of the temperature sensor 15a of the catalyst unit of the high-temperature shift unit 15. Since the cooling water 1 is not supplied to the heat exchanger 14a, the catalyst temperature T1 of the high-temperature shift section 15 rises rapidly.
(d) When the temperature of the catalyst unit of the high-temperature shift unit 15 becomes, for example, 270 ° C. due to internal heat transfer, the control unit 50 supplies methanol and bypass water to the evaporation unit 12. Methanol and bypass water are supplied to the reforming section 13 as high-temperature gas in a heat exchanger (not shown) of the evaporating section 12, and high-temperature reformed gas is generated. As the temperature of the reforming section 13 rises and the generated reformed gas is generated, the catalyst temperature T1 of the high-temperature shift section 15 rises slightly to overshoot.
(e) For example, when the catalyst temperature T1 of the high-temperature shift unit 15 reaches 350 ° C., the control unit 50 stops supplying the bypass water and supplies the same amount of the cooling water 1 to the heat exchanger 14a. At this time, since the on-off valve 31 is still closed and the on-off valve 32 is open, the cooling water 1 heated by the heat exchanger 14a passes through the on-off valve 32 and the bypass flow path BP to generate heat of the CO purifying unit 18. It is supplied to the exchanger 18a. Since the cooling water 3 is not supplied, the heat exchanger 18a is heated by the cooling water 1 of the heat exchanger 14a.
(f) When the temperature T1 of the heat exchanger 14a decreases to about 300 ° C. by passing water, the control unit 50 adjusts (decreases) the flow rate of the cooling water 1 to stabilize the catalyst temperature of the high-temperature shift unit 15 at 300 ° C. The reduced flow is compensated by passing the bypass water.
(g) The controller 50 opens the on-off valve 31 and closes the on-off valve 32 when the supply of the heated cooling water 1 causes the catalyst temperature T3 of the CO purification unit 18 to exceed about 120 ° C. The supply destination is switched from the CO purification unit 18 to the evaporation unit 12.
(h) When the temperature of the low-temperature shift unit 17 reaches about 150 ° C., the control unit 50 starts supplying the cooling water 2. The flow rate of the bypass water corresponding to the supply amount is reduced.
(i) When the temperature T2 of the low-temperature shift unit 17 reaches about 200 ° C., the control unit 50 sets (decreases) the cooling water 2 to a flow rate at which this temperature can be maintained, and uses the reduced water by bypass water. compensate.
(j) When the temperature of the CO purification unit 18 rises to about 150 ° C., the control unit 50 starts flowing the cooling water 3 and maintains the temperature. This passing water is reduced from the bypass water.
(k) The control unit 50 is assigned so that the total amount of the bypass water and each cooling water described above becomes the amount of the reforming water required by the reforming unit 13. In other words, the difference between the required reforming water amount and each cooling water amount is supplemented by bypass water.
[0041]
In this way, the cooling water heated in the upstream high-temperature section promotes the temperature rise in the most downstream CO purification section 18, so that the riser of the reformer is quickened and the startup time of the fuel cell system is shortened. Is done.
[0042]
(Comparative example)
FIG. 3 shows a reformer of a comparative example. In the figure, parts corresponding to those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and description of such parts is omitted. In the comparative example, the cooling waters 1 to 3 are used as in the first embodiment described above, but the cooling waters 1 to 3 are supplied to the cooling units 14 and 16 and the CO purification unit 18 after the fuel cell system is started. It is configured to supply.
[0043]
FIG. 4 shows the supply of the cooling water 1 to 3 and the temperature rise characteristics of the cooling units 14 and 16 and the CO purifying unit 18 in this case. In the rising characteristics shown in FIG. 4, the portions corresponding to the characteristics shown in FIG. 2 are denoted by the same reference numerals.
[0044]
The reformed gas and the reformed water supplied upstream of the reformer are heated, turned into a high-temperature gas containing steam, and transported downstream. However, since the temperature of the downstream catalyst is low at the time of start-up, the steam becomes condensed water after heating the catalyst and adheres to the catalyst. In order to convert this condensed water into steam, a high-temperature gas from further upstream is required. Therefore, the temperature of the downstream catalyst is constant at around 100 ° C. for a long time at the time of startup, and it takes a long time to reach an appropriate temperature. As a countermeasure, an electric heater or the like is often used for the catalyst on the downstream side. However, since electric energy is required, the efficiency is reduced. Further, in the heater, the temperature distribution and the heat radiation to the outside easily occur.
[0045]
On the other hand, in the first embodiment, the flow path of the cooling water heated in the high-temperature section on the upstream side can be switched, thereby heating the low-temperature catalyst on the downstream side, so that the temperature rise of the downstream-side catalyst is promoted. As a result, the rise of the reformer is quickened, and the start-up time of the fuel cell system is reduced.
[0046]
(Second embodiment)
FIG. 5 shows a second embodiment of the present invention. In the figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description of such parts is omitted.
[0047]
In this embodiment, the cooling waters 1 to 3 are supplied from one cooling water supply source. The cooling water supply source includes a water tank 41 storing cooling water (reformed water) and a pump 42. The cooling water 1 is supplied from the pump 42 to the cooling unit 14 via the flow paths L1 and L2 and the flow control valve 35. The supply amount of the cooling water 1 can be set by adjusting the opening of the flow control valve 35. The cooling water 2 is supplied from the pump 42 to the cooling unit 16 via the flow paths L1, L3 and the flow control valve 36. The supply amount of the cooling water 2 can be set by adjusting the opening of the flow control valve 36. The cooling water 3 is supplied from the pump 42 to the CO purification unit 14 via the flow paths L1 and L4 and the flow control valve 37. The supply amount of the cooling water 3 can be set by adjusting the opening of the flow control valve 37. In addition, the bypass water is supplied from the pump 42 to the evaporating unit 12 via the flow paths L1, L9, the flow control valves 38, and L10. By adjusting the opening of the flow control valve 35, the supply amount of bypass water can be set. As described above, the bypass water is used to compensate for the shortage of the cooling water that is heated and used as the reforming water, and to secure a required amount of the reforming water. The flow control valves 35 to 38 are controlled by the control unit 50.
[0048]
(Third embodiment)
FIG. 6 shows a third embodiment of the present invention. In the figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description of such parts is omitted.
[0049]
In this embodiment, the cooling water 1 heated by the heat exchanger 14a on the upstream side of the reformer 10 can be selectively or simultaneously supplied to the plurality of heat exchangers 16a and 18a arranged on the downstream side so that the cooling water 1 can be supplied on the downstream side. The configuration is such that the temperature rise of the reaction section is accelerated. For this reason, the heated cooling water 1 is led to the downstream side by the bypass flow path BP, and is further heated by the heat exchangers 16a and 18a by the bypass flow paths BP1 and BP2 branched from the bypass flow path BP. Supply. Opening / closing valves 33 and 34 are provided in the bypass passages BP1 and BP2, respectively, and by controlling these valves, heating / cooling water can be supplied to the downstream heat exchangers 16a and 18a simultaneously or individually. . With such a configuration as well, the temperature rise of the downstream catalyst is promoted, the rise of the reformer is accelerated, and the startup time of the fuel cell system is shortened.
[0050]
(Fourth embodiment)
FIG. 7 shows a fourth embodiment of the present invention. In the figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description of such parts is omitted.
[0051]
In this embodiment, the heated cooling water is supplied from a heat exchanger arranged in the reforming section 13 of the reformer 10 to a lower-temperature heat exchanger arranged on the downstream side. As described above, the reforming unit 13 generates hydrogen by an oxidation reforming reaction and a steam reforming reaction, and includes a first reforming unit (reaction unit) having a catalyst unit for performing a higher-temperature oxidation reforming reaction. ) 131, and a second reforming section (reaction section) 133 having a catalyst unit for performing a steam reforming reaction at a relatively low temperature. The catalyst unit of the first reforming section 131 is provided with a heat exchanger 132 for maintaining an optimum temperature for the reaction of the catalyst. The catalyst unit of the second reforming section 133 is also provided with a heat exchanger 134 for maintaining a temperature optimum for the reaction of the catalyst. As in the first embodiment, the cooling water 1 is supplied to the heat exchanger 132 at the time of startup, and the heated cooling water 1 is provided to the catalyst unit of the downstream CO purification unit 18 via the on-off valve 32. By being supplied to the heat exchanger 18a, the temperature rise of the catalyst unit of the CO purification unit 18 disposed downstream of the reformed gas flow path is promoted, the rise of the reformer is accelerated, and the start of the fuel cell system is started. Time is reduced.
[0052]
(Fuel cell system)
Next, an example of a fuel cell system using the fuel reformer 1 having the above-described cooling water supply system will be described with reference to FIG. In the figure, the same reference numerals are given to portions corresponding to FIG. 6, and description of such portions will be omitted.
[0053]
As shown in FIG. 8, raw fuel is supplied to the reformer 10 of the fuel reformer from the fuel supply system 60, oxidized air is supplied from the air supply system 20, and refrigerant (transfer) is supplied from the cooling water supply system 30. Cooling water is supplied as a heat carrier. The heated cooling water is used as reforming water.
[0054]
The fuel supply system 60 includes a fuel tank 61 storing methanol, fuel pumps 63 and 64, a fuel flow path (piping), and the like. The burner of the combustion unit 11 of the reformer 10 reforms the fuel and the evaporation unit 12. Supply fuel (raw fuel). The fuel supply to each section is controlled by the control section 50.
[0055]
The air supply system 20 includes an air filter 21, a motor 22, an air pump 23, an air tank 24, a drive circuit 25, an air flow path, and the like. The air supply system 20 includes a combustion unit 11, a reforming unit 13, a CO purification unit 18, a fuel cell 70, and the like. Supply oxidizing air. The motor 22 is a DC motor, and operates by receiving a PWM output from a motor drive circuit 25 controlled by the control unit 50. The motor drive circuit 25 receives power from a secondary battery (or capacitor) 80.
[0056]
The cooling water supply system 30 has the same configuration as that shown in FIG. 5 and includes on-off valves 31 and 32, flow rate adjustment valves 35 to 38, flow paths L1 to L10, a reforming water tank 41, a pump 42, and the like. I have. The water generated in the fuel cell 70 is collected in the reforming water tank 41. The operation of each valve is controlled by the control unit 50.
[0057]
Air for combustion is supplied from the air tank 24 to the combustion section 11 of the reformer 10, and methanol for combustion is supplied from the fuel tank 61 via the pump 63. Further, residual gas such as hydrogen remaining without being used is also supplied from the fuel cell 70. To the evaporator 12, methanol as raw fuel to be reformed and water used for the reforming reaction are supplied via a cooling water supply 30. The reformed water is used as a refrigerant (heat transfer medium) in each reaction section by a heat exchanger disposed in each reaction section in order to maintain the catalyst unit and the like in each reaction section of the reformer 10 described above at a predetermined temperature. Heat is supplied from the reformed gas and heated to be supplied to the evaporator 12. Thereby, the thermal efficiency is improved.
[0058]
The methanol and water vaporized in the evaporating section become a hydrogen-rich reformed gas by a steam reforming reaction in the reforming section 13, and each reaction section (high-temperature shift section 15, low-temperature shift section 17, CO purification section 18) converts carbon monoxide. Reduced. This reformed gas is supplied to the hydrogen electrode of the fuel cell 70. Oxidized air is supplied from the air tank 24 to the oxygen electrode. As a result, electricity is generated at the output end of the fuel cell 70. The electric output generated by the fuel cell 70 is supplied to a secondary battery 80 and an inverter that drives a drive motor of a vehicle (not shown). As described above, as the secondary battery 80, for example, a nickel-metal hydride secondary battery can be used, but a large-capacity capacitor may be used. In this case, there is an advantage that the weight can be reduced. The secondary battery 80 supplies necessary power to the accessories of the fuel cell 70.
[0059]
A control unit 50 that operates the fuel cell system 1 drives pumps, a flow control valve, and the like, and an input / output port 52 that converts an output of a temperature sensor or a pressure sensor of each unit supplied from the outside into a digital signal. It comprises a CPU 54 for executing a control process according to a program, a ROM 56 for storing a control program and control data, a RAM 58 used for data processing, and the like. The control unit 50 includes a fuel sensor such as a temperature sensor, a pressure sensor, a CO sensor, an output voltage sensor, an output current sensor, a valve opening sensor, a vehicle opening information from another computer, and the like, which are provided in each part of the fuel cell system 1. An information signal required for battery operation control is input. The control unit 50 appropriately processes the information to control the above-described on-off valves 31 and 32, the flow rate regulating valves 35 to 38, the pumps 22, 42, 63 and 65, the motor drive circuit 25, and the like.
[0060]
In this manner, the fuel reformer and the fuel cell system of the present invention allow the pump 24 to be used at a low pressure by providing the means for preventing backflow in the reformer, and the fuel cell system itself can be used. Since the power consumption is reduced, the efficiency of fuel use is improved and the condition is good.
[0061]
In the embodiment shown in FIG. 8, the oxidizing air is supplied from one air tank 24 to the combustion unit 11 and the fuel cell 70, but the oxidizing air may be supplied separately by separate pumps.
[0062]
Further, a flow regulating valve and a check valve may be provided on the oxidizing air supply route to the combustion unit 11 and the oxidizing air supply route to the fuel cell 70, respectively. Thereby, it becomes possible to suppress the flow rate setting and the air pressure fluctuation.
[0063]
Further, the tank 24 is not essential, and air may be directly supplied from the pump to the main pipe 25 without providing the tank 24.
[0064]
Further, the opening / closing valves 31 and 32 can be replaced with flow rate adjusting valves capable of continuously adjusting the flow rate.
[0065]
【The invention's effect】
As described above, according to the fuel reforming apparatus and the fuel cell system of the present invention, the heat exchange of the reaction unit disposed on the upstream side of the reformed gas flow path of the reformer at the time of starting the fuel cell system. Since the heat transfer medium heated by the heat exchanger or the higher-temperature heat exchanger can be selectively supplied to the heat exchanger of the reaction unit arranged on the downstream side, the temperature increase of the downstream reaction unit is promoted. The overall temperature rise time of the reaction section is reduced. Thereby, the startup time of the fuel cell system can be reduced, which is favorable.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a fuel reforming apparatus of the present invention.
FIG. 2 is a graph illustrating an operation of a cooling water system of the fuel reformer of the present invention.
FIG. 3 is an explanatory view showing a fuel reforming apparatus of a comparative example.
FIG. 4 is a graph illustrating an operation of a cooling water system of a fuel reformer of a comparative example.
FIG. 5 is an explanatory diagram illustrating a second embodiment of the fuel reformer of the present invention.
FIG. 6 is an explanatory diagram illustrating a third embodiment of the fuel reformer of the present invention.
FIG. 7 is an explanatory diagram illustrating a fourth embodiment of the fuel reformer of the present invention.
FIG. 8 is an explanatory diagram illustrating a third embodiment of the fuel cell system using the fuel reformer of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel reformer, 2 ... Fuel cell system, 10 ... Reformer, 20 ... Air supply system, 30 ... Cooling water supply system, 60 ... Fuel supply system, 31, 32 ... On-off valve, 35-38 ... Flow rate Regulating valve, BP, BP1, BP2 ... bypass passage for cooling water

Claims (10)

An evaporator for gasifying raw fuel and water;
A plurality of reaction units provided along a reformed gas flow path for reforming gasified raw fuel and water,
A plurality of heat exchangers provided in each reaction section,
Heat medium supply means for supplying a heat transfer medium to each heat exchanger,
A bypass that enables a heat transfer medium to be supplied from the heat exchanger of the first reaction section having a higher temperature among the plurality of reaction sections to the heat exchanger of the second reaction section having a relatively lower temperature. Means,
Control means for operating the bypass means when the internal temperature of the second reaction section is equal to or lower than a predetermined temperature;
A fuel reformer comprising: An evaporator for gasifying raw fuel and water;
A plurality of reaction units provided along a reformed gas flow path for reforming gasified raw fuel and water,
A plurality of heat exchangers provided in each reaction section,
Heat medium supply means for supplying a heat transfer medium to each heat exchanger,
It is possible to supply a heat transfer medium from the heat exchanger of the first reaction unit provided on the upstream side of the flow path of the reformed gas to the heat exchanger of the second reaction unit provided on the downstream side. Means for bypassing;
Control means for operating the bypass means when the internal temperature of the second reaction section is equal to or lower than a predetermined temperature;
A fuel reformer comprising: 3. The method according to claim 1, wherein the bypass unit supplies the heat transfer medium simultaneously or individually from the heat exchanger of the first reaction section to the heat exchangers of at least two second reaction sections. 4. Fuel reformer. 4. The fuel reformer according to claim 1, wherein the bypass unit directly supplies the heat transfer medium from the heat exchanger of the first reaction section to the heat exchanger of the second reaction section. 5. apparatus. 5. The catalyst according to claim 1, wherein one of the plurality of reaction units includes a catalyst that generates a hydrogen-rich reformed gas from the gasified raw fuel and water, and the heat exchanger sets the catalyst to an optimum temperature. The fuel reformer according to any one of the above. 5. The fuel reformer according to claim 1, wherein any one of the plurality of reaction units includes a catalyst for oxidizing carbon monoxide, and the heat exchanger sets the temperature to an optimum temperature of the catalyst. 6. The fuel reformer according to claim 1, wherein the control unit operates the bypass unit when the device is started. The fuel reformer according to any one of claims 1 to 7, wherein the heat transfer medium is water, and water heated via the heat exchanger is supplied to the evaporator. 9. The fuel according to claim 8, wherein a difference between a flow rate of water heated via the heat exchanger and supplied to the evaporator and a flow rate of water required by the evaporator is compensated for by supply of bypass water. Reformer. A fuel cell system comprising: the fuel reforming apparatus according to any one of claims 1 to 9; and a fuel cell that generates electricity by receiving a supply of reformed gas from the fuel reforming apparatus.

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