JP2005166580A - Fuel reformer, fuel cell system and operation control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel reformer capable of promptly achieving a temperature rise of each catalyst at startup. <P>SOLUTION: This fuel reformer is equipped with: a reforming catalyst; a modification catalyst; a selective oxidation catalyst; a combustion catalyst for heating the reforming catalyst; a first heating means for supplying heat to the combustion catalyst; and a second heating means for supplying a raw fuel gas to the combustion catalyst when the temperature of the combustion catalyst reaches a value capable of burning the raw fuel gas to heat the reforming catalyst by heat generated in burning the raw fuel gas in the combustion catalyst. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is used to generate hydrogen necessary for a fuel cell or the like, and converts a raw fuel gas made of hydrocarbons into hydrogen-rich reformed gas by steam, and a fuel reformer of the fuel reformer The present invention relates to an operation control method. Furthermore, the present invention relates to a fuel cell system including a fuel reformer and a fuel cell that uses hydrogen generated by the fuel reformer as a fuel, and an operation control method for the fuel cell system.

  The fuel reformer reforms a raw fuel gas composed of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas with steam under a reforming catalyst in a reforming unit, and converts the reformed gas into a transformation unit The carbon monoxide gas in the reforming process gas is converted to carbon dioxide gas under the shift catalyst at, and the shift process gas is converted into one of the shift process gas under the selective oxidation catalyst in the selective oxidation section. A selective oxidation treatment is performed by selectively oxidizing oxygen oxide to generate a hydrogen-rich hydrogen-containing gas having a low carbon monoxide concentration. The generated hydrogen-containing gas is, for example, a fuel gas for a power generation reaction in a fuel cell. Used as

  During operation of the fuel reformer, the reforming catalyst is at a temperature suitable for reforming (hereinafter also referred to as reforming temperature), the shift catalyst is at a temperature suitable for reforming processing (hereinafter also referred to as shift processing temperature), It is necessary to maintain the selective oxidation catalyst at a temperature appropriate for the selective oxidation treatment (hereinafter also referred to as a selective oxidation temperature). The reforming treatment temperature is, for example, in the range of 600 to 700 ° C., the modification treatment temperature is in the range of, for example, 150 to 250 ° C., and the selective oxidation treatment temperature is in the range of 80 to 150 ° C.

  In a fuel reformer, there is a demand for a technique capable of operating while maintaining a reforming catalyst, a shift catalyst, and a selective oxidation catalyst at appropriate temperatures with simple control.

  As a conventional technique, a reforming catalyst, a shift catalyst, and a selective oxidation catalyst are provided so that a shift catalyst is located between the reforming catalyst and the selective oxidation catalyst and heat transfer can be performed between adjacent ones. Adjusting the heating capacity of the reforming burner so as to maintain the temperature suitable for the reforming treatment, and cooling the selective oxidation unit cooling means so as to maintain the selective oxidation catalyst at a temperature suitable for the selective oxidation treatment. A fuel reformer operation control method for adjusting the capacity is known (see, for example, Patent Document 1).

  In the above method, by conducting heat from the reforming catalyst to the shift catalyst and the selective oxidation catalyst, that is, by conducting heat from the high temperature part to the low temperature part, the heat can be used effectively and each part can be heated quickly. Has the advantage. However, the reforming catalyst is heated only by a burner for supplying heat necessary for the reforming reaction, and there is not enough heat to sufficiently heat the entire apparatus, and the reforming catalyst is heated to the reforming treatment temperature. It took a long time.

Further, in the above system, even during normal operation, the granular reforming catalyst is heated using a burner, so that the temperature difference between the heating means of the reforming section and the reforming catalyst is large. In the embodiment of Patent Document 1, the set temperature of the reforming catalyst is 642.9 ° C., whereas the temperature of the burner is 838.7 ° C., and there is a temperature difference of about 200 ° C. When the temperature difference between the heating means (burner in Patent Document 1) and the object to be heated (reforming part) is large, it is necessary to use a material having temperature resistance matched to the temperature of the heating means as the material of each part, and the cost May not only be high, but may be difficult to manufacture. In addition, the amount of fuel consumption increases and the cost of normal operation increases.
JP 2002-356309 A

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a fuel reformer and an operation control method thereof that can quickly increase the temperature of each catalyst during startup. That is, it is an object of the present invention to provide a fuel reformer capable of shortening the temperature rise time to a predetermined temperature of the reforming catalyst at the time of start-up and an operation control method thereof. It is another object of the present invention to provide a fuel reforming apparatus and an operation control method thereof capable of quickly raising the temperature of each part to an appropriate temperature by simple means regardless of the shape of each part of the fuel reforming apparatus. It is another object of the present invention to provide a fuel cell system including the fuel reforming and the fuel cell and an operation control method thereof.

  In order to achieve the above object, the fuel reformer of the present invention performs a reforming process to a gas containing hydrogen gas and carbon monoxide gas by reacting a raw fuel gas composed of hydrocarbon with water vapor under a reforming catalyst. A reforming section that transforms the carbon monoxide gas in the reforming process gas into carbon dioxide gas under the shift catalyst, and the reforming section that is supplied from the reforming section, A selective oxidation unit that selectively oxidizes the shift gas supplied from the shift unit by selectively oxidizing carbon monoxide gas in the shift gas under a selective oxidation catalyst, and a combustion catalyst that heats the reforming catalyst And a first heating means for supplying heat to the combustion catalyst, and when the temperature of the combustion catalyst reaches a temperature at which the raw fuel gas can be combusted, the raw fuel gas is supplied to the combustion catalyst. In the combustion catalyst And second heating means for heating the reforming catalyst by the heat generated during combustion of Kihara fuel gas, a structure comprising a. By heating the combustion catalyst using the first heating means and heating the reforming catalyst using the second heating means, the temperature increase rate of the combustion catalyst and the reforming catalyst can be increased.

  Preferably, an inert gas is circulated in the order of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst, and the inert gas heats the reforming catalyst downstream from the shift catalyst and the selective oxidation catalyst. And a circulation means for heating the shift catalyst and the selective oxidation catalyst. Due to the inert gas circulated, the temperature of the shift catalyst and the selective oxidation catalyst can be quickly increased, and the burden on each catalyst due to heating can be reduced.

  For example, a burner can be used as the first heating means.

  Further, the fuel reformer of the present invention includes a reforming unit that reforms a raw fuel gas made of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas by reacting with steam under a reforming catalyst; A reforming unit that converts the reforming process gas supplied from the reforming unit by converting carbon monoxide gas in the reforming process gas into carbon dioxide gas under a shift catalyst, and is supplied from the shift unit A selective oxidation section that selectively oxidizes the carbon monoxide gas in the shift treatment gas under a selective oxidation catalyst, an inert gas, the reforming catalyst, the shift catalyst, A circulating means for circulating the selective oxidation catalyst in order, supplying heat of the reforming catalyst to the shift catalyst and the selective oxidation catalyst in the downstream by the inert gas, and heating the shift catalyst and the selective oxidation catalyst; With And it formed.

  An operation control method for a fuel reformer according to the present invention includes a reforming unit that reforms a raw fuel gas composed of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas by reacting with steam under a reforming catalyst. A reforming section that performs a reforming process by transforming the carbon monoxide gas in the reforming process gas into a carbon dioxide gas under a shift catalyst under the reforming process gas supplied from the reforming section; A selective oxidation section that selectively oxidizes the supplied shift treatment gas by selectively oxidizing carbon monoxide gas in the shift treatment gas under a selective oxidation catalyst, a combustion catalyst that heats the reforming catalyst, and the combustion An operation control method for a fuel reformer comprising: a first heating means for supplying heat to the catalyst, wherein the first heating means heats the combustion catalyst by the first heating means; Temperature is the raw fuel gas A second heating step of supplying the raw fuel gas to the combustion catalyst after reaching a combustible temperature and heating the reforming catalyst by heat generated during combustion of the raw material gas in the combustion catalyst; . By controlling in this way, the temperature increase rate of the combustion catalyst and the reforming catalyst can be increased. In the second heating step, the fuel catalyst may be heated by the first heating means together with the heating of the reforming catalyst.

  Preferably, an inert gas is circulated in the order of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst, and heat of the reforming catalyst is circulated downstream of the shift catalyst and the selection by circulation of the inert gas. Supplying the oxidation catalyst and heating the shift catalyst and the selective oxidation catalyst.

  Further, the operation control method of the fuel reformer of the present invention is a modified method in which a raw fuel gas composed of hydrocarbon is reacted with water vapor under a reforming catalyst to reform to a gas containing hydrogen gas and carbon monoxide gas. A reforming section for transforming the reforming process gas supplied from the reforming section by transforming carbon monoxide gas in the reforming process gas into carbon dioxide gas under a shift catalyst; and An operation control method for a fuel reforming apparatus including a selective oxidation unit that selectively oxidizes a carbon dioxide gas in a shift treatment gas supplied from a section under a selective oxidation catalyst by selectively oxidizing carbon monoxide gas in the shift treatment gas. The inert gas is circulated in the order of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst, and the heat of the reforming catalyst is circulated behind the shift catalyst and the selective oxidation catalyst by circulating the inert gas. To supply before Shift catalyst and a step of heating the selective oxidation catalyst.

  The fuel cell system according to the present invention includes the fuel reformer, a fuel cell that uses the hydrogen-containing gas generated by the fuel reformer as a fuel, and heat generated by the power generation of the fuel cell as a heat source. The first heating means is also a means for heating the water in the water storage tank. According to such a configuration, the number of devices can be reduced.

  An operation control method for a fuel cell system according to the present invention includes a fuel reformer, a fuel cell using hydrogen-containing gas generated by the fuel reformer as a fuel, and heat generated by power generation of the fuel cell. An operation control method of a fuel cell system comprising a water storage tank for storing heated water as a heat source, wherein the fuel reformer reacts a raw fuel gas composed of hydrocarbon with steam under a reforming catalyst A reforming section for reforming the gas containing hydrogen gas and carbon monoxide gas, and the carbon monoxide gas in the reforming process gas supplied from the reforming section under a shift catalyst A conversion unit that converts the carbon monoxide gas into a carbon dioxide gas, and a selective acid by selectively oxidizing the carbon monoxide gas in the shift treatment gas under the selective oxidation catalyst of the shift treatment gas supplied from the shift unit A first oxidation unit that heats the combustion catalyst by a first heating unit; a selective oxidation unit to be treated; a combustion catalyst that heats the reforming catalyst; and a first heating unit that supplies heat to the combustion catalyst. Heating process, and after the temperature of the combustion catalyst reaches a temperature at which the raw fuel gas can be combusted, the raw fuel gas is supplied to the combustion catalyst, and heat generated during combustion of the raw material gas in the combustion catalyst A second heating step for heating the reforming catalyst, and a step for heating the water in the water storage tank by a first heating means. In the second heating step, the fuel catalyst may be heated by the first heating means together with the heating of the reforming catalyst.

  Here, the materials for the reforming catalyst, the shift catalyst, the selective oxidation catalyst, and the combustion catalyst are preferably copper, chromium, manganese, nickel, iron, cobalt, ruthenium, rhodium, palladium, platinum, gold, silver, magnesium, calcium. Selected from metals selected from lanthanum, titanium, zirconium, yttrium and cerium or oxides of these metals. Each catalyst is supported on a metal base material in any shape of a plate, tube, finned tube, corrugated plate and finned plate made of materials such as aluminum, aluminum alloy, stainless steel and copper, for example. It may be configured (hereinafter collectively referred to as a plate-type catalyst) or may be filled with a granular material made of the above catalyst material. Note that the combustion catalyst and the reforming catalyst are disposed adjacent to each other, and in order to efficiently conduct heat generated in the combustion catalyst to the reforming catalyst, the reforming catalyst, the shift catalyst, the selective oxidation catalyst, and the combustion catalyst. It is preferable to use a plate-type catalyst as the catalyst.

  According to the present invention, in the fuel reformer, heating of the reforming catalyst to a predetermined temperature can be achieved in a short time. Further, heating of the shift catalyst and the selective oxidation catalyst to a predetermined temperature can be achieved quickly.

  According to the present invention, in the fuel cell system, the heating means used in the fuel reformer and the heating means used in the fuel cell can be used together, so that the number of equipment can be reduced. In addition, since the supply of fuel from the fuel reformer is achieved in a short time after startup, rapid supply of electricity by the fuel cell is possible.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications.

(First embodiment)
The fuel cell system according to the first embodiment will be described below based on the drawings. FIG. 1 is a flow sheet showing the fuel cell system of the present embodiment. The fuel cell system includes a fuel reformer 1, a fuel cell 60, a water storage tank 19, and the like.

  As shown in FIG. 1, the fuel reformer 1 includes a desulfurization unit 15 that desulfurizes a raw fuel gas made of supplied hydrocarbon, and an evaporation unit 30 that heats supplied distilled water to generate steam. The reforming unit 20 for reforming the desulfurized raw fuel gas into a gas containing hydrogen gas and carbon monoxide gas using the steam generated in the evaporation unit 30, and the reforming process gas supplied from the reforming unit 20 By transforming the carbon monoxide gas therein into carbon dioxide gas by using water vapor, the modification section 40 that performs modification treatment, and selectively oxidizing the carbon monoxide gas in the modification treatment gas supplied from the modification section 40 A selective oxidation unit 50 that performs selective oxidation treatment and a control unit (not shown) are provided, and are configured to generate a hydrogen-rich hydrogen-containing gas having a low carbon monoxide gas concentration.

  The fuel cell 60 is a solid polymer fuel cell using a polymer membrane as an electrolyte. The hydrogen-containing gas generated by the fuel reformer 1 is supplied as fuel gas to the anode 61 of the fuel cell 60. Since carbon monoxide in the fuel gas becomes a catalyst poison of the electrode catalyst of the fuel cell and causes a reduction in the battery life, the fuel reformer 1 uses hydrogen with a low carbon monoxide gas concentration as described above. It is configured to generate a rich hydrogen-containing gas.

  In the desulfurization unit 15, for example, sulfur compounds in the raw fuel gas are hydrogenated by the desulfurization catalyst at a desulfurization treatment temperature in the range of 150 to 270 ° C., and the hydride is adsorbed by zinc oxide and desulfurized. The desulfurization reaction in the desulfurization unit 15 is an exothermic reaction. In the present specification, “˜” means the following, and “150 to 270 ° C.” means 150 ° C. or more and 270 ° C. or less. In the present embodiment, all the raw fuel gas to be supplied passes through the desulfurization section 15, but only the reforming raw fuel gas may pass through the desulfurization section 15.

In the reforming unit 20, it is supplied from the raw fuel gas and the evaporation processing unit 32 that are supplied via the valve V <b> 2 at a reforming processing temperature in the range of 600 to 700 ° C., for example, by the catalytic action of the reforming catalyst 22. Steam undergoes a reforming reaction, and reforming is performed to a gas containing hydrogen gas and carbon monoxide gas. The reforming reaction in the reforming unit 20 is an endothermic reaction. When the raw fuel gas is methane gas, the reforming reaction is represented by the following chemical reaction formula (1).

[Chemical 1]
CH ₄ + H ₂ O → CO + 3H ₂ (1)

In the shift unit 40, the carbon monoxide gas and the water vapor in the reforming process gas are converted into the following chemical reaction formula (at a shift processing temperature in the range of, for example, 150 to 250 ° C.) by the catalytic action of the shift catalyst 41: In step 2), the carbon monoxide gas is converted into carbon dioxide gas through a metamorphic reaction.

[Chemical 2]
CO + H ₂ O → CO ₂ + H ₂ (2)

The reaction of the chemical reaction formula (2) in the shift catalyst 41 is an exothermic reaction. Therefore, the shift unit 40 includes a cooling unit 42 in order to keep the shift catalyst 41 at an appropriate temperature. The cooling unit 42 performs air cooling with air supplied from the outside.

In the selective oxidation unit 50, the carbon monoxide gas remaining in the shift treatment gas is supplied via the valve V7 under the selective oxidation treatment temperature of, for example, 80 to 150 ° C. by the catalytic action of the selective oxidation catalyst 51. Is selectively oxidized by the following chemical reaction formula (3).

[Chemical formula 3]
CO + (1/2) O ₂ → CO ₂ (3)

The reaction of the chemical reaction formula (3) in the selective oxidation catalyst 51 is an exothermic reaction. Therefore, the selective oxidation unit 50 includes a cooling unit 52 for keeping the selective oxidation catalyst 51 at an appropriate temperature. The cooling unit 52 performs air cooling with air supplied from the outside. Note that the cooling method of both the cooling unit 42 of the transformation unit 40 and the cooling unit 52 of the selective oxidation unit 50 is not limited to air cooling. Any cooling method that can maintain each of the shift catalyst 41 and the selective oxidation catalyst 51 at an appropriate temperature may be used.

The hydrogen-containing gas generated by the fuel reformer 1 is supplied to the fuel cell 60 as fuel gas. The fuel cell 60 simultaneously generates water by an electrochemical reaction between hydrogen gas supplied from the fuel reformer 1 to the anode 61 and oxygen in the reaction air supplied from a blower (not shown) to the cathode 62. It is the structure which generates electric power. The reaction in the fuel cell 60 is represented by the following chemical reaction formula (4).

[Chemical formula 4]
H ₂ + (1/2) O ₂ → H ₂ O (4)

The electricity generated in the fuel cell 60 is taken out (not shown). In addition, since there is a slight electrical resistance inside the fuel cell 60, thermal energy is generated and the temperature of the inside rises. Therefore, the fuel cell 60 is configured so that the heat recovery unit 63 recovers heat with distilled water supplied via the water circulation pump 7 and cools the temperature rising portion. The hot water discharged from the heat recovery unit 63 is supplied to the heat exchanging unit 70, where it is thermally conducted to the hot water supply water to heat the hot water supply water. The heated hot water is stored in the water storage tank 19 and taken out to the outside as needed. Further, water generated by the electrochemical reaction in the fuel cell 60 is discharged from the cathode 62 mixed with the exhaust, and the exhaust is sent to the heat exchange unit 70. The water in the exhaust is recovered as distilled water in the heat exchanging unit 70. Hot water in the water storage tank 19 is heated by the burner 11 via the heat exchanger 82. The amount of water heated here is adjusted by a pump 81.

In the burner 11, a high temperature is generated by a combustion reaction represented by the following chemical reaction formula (5) between the raw fuel gas supplied via the valve V1 and oxygen in the air supplied from the air blower 12 via the valves V6 and V4. The combustion gas is generated. Heating by the burner 11 uses high-temperature combustion gas as a heat medium.

[Chemical formula 5]
CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O (5)

The reforming catalyst 22, the shift catalyst 41, and the selective oxidation catalyst 51 are heated during start-up operation, and are maintained at the above-described appropriate temperatures during normal operation. A heating method during start-up operation of each catalyst will be described. The reforming catalyst 22 conducts heat from the adjacent combustion catalyst 21 and is heated. The shift catalyst 41 and the selective oxidation catalyst 51 are heated by the circulation blower 13 using the inert gas circulated in the order of the reforming catalyst 22, the shift catalyst 41 and the selective oxidation catalyst 51 as a heat medium (circulation means). When the reforming catalyst 22 is heated by the combustion catalyst 21, the temperature rises, and the temperature of the inert gas delivered from the reforming catalyst 22 also rises. The shift catalyst 41 and the selective oxidation catalyst 51 that are heated using such an inert gas as a heat medium increase in temperature as the reforming catalyst 22 increases in temperature. In addition, as a heating means for the shift catalyst 41 and the selective oxidation catalyst 51, another heating means may be provided.

  The degree of temperature increase of the shift catalyst 41 and the selective oxidation catalyst 51 varies depending on conditions such as the configuration of each catalyst and the flow rate of the inert gas. In the present embodiment, the selective oxidation catalyst 51 can be controlled to 80 to 150 ° C. while the reforming catalyst 22 is maintained at 600 to 700 ° C., and the shift catalyst 41 is 150 to 250 in such a state. Each catalyst is configured and each condition is set so that the temperature is 0C. Accordingly, since the inert gas passing through the circulation blower 13 is 150 ° C. or less, the circulation blower 13 may be configured to have a heat resistance of 150 ° C.

  Nitrogen gas is preferably used as the inert gas circulated by the circulation blower 13. When the operation of the fuel reformer 1 is stopped, the flow path connecting the reforming catalyst 22, the shift catalyst 41, the selective oxidation catalyst 51, and the reforming catalyst 22 is connected to the valve V7 in order to isolate the reforming catalyst 22 from oxygen in the air. It is made to fill with the inert gas supplied through this. Therefore, at the time of start-up operation, the inert gas filled at the time of stop is only circulated by the circulation blower 13, and supply of new inert gas is unnecessary. During normal operation, the flow path serves as a flow path for reformed gas delivered from the reforming catalyst 22, so that the inert gas in the flow path is removed from the valves V8 and V9 during the transition to normal operation. , V10 and the combustion catalysts 31 and 21, and exhausted from the exhaust port at the rear of the heat recovery unit 33.

  The combustion catalyst 21 is heated by the burner 11 during the starting operation (first heating means). The burner 11 is a burner for heating hot water in the water storage tank 19 and can be of a large capacity because it uses fuel such as city gas. Therefore, it is possible to raise the temperature of the combustion catalyst 21 in a short time with a small number of devices. Further, when the combustion catalyst 21 reaches a temperature at which the raw fuel gas can be combusted (for example, 600 to 700 ° C.), the raw fuel gas is supplied via the valve V3, and the above chemical reaction formula ( The combustion reaction shown in 5) occurs, and the combustion heat generated by the combustion reaction contributes to the heating of the reforming catalyst 22 (second heating means). The heating of the reforming catalyst 22 can be promoted by the heating by the first heating means and the second heating means.

The heating of the reforming catalyst 22 during normal operation is due to the combustion of the anode off-gas in the combustion catalyst 21 and the combustion of the raw fuel gas. The anode off gas is hydrogen gas that is discharged from the fuel cell 60 and supplied via the valve 10. The combustion reaction of the anode off gas is represented by the following chemical reaction formula (6).

[Chemical 6]
H ₂ + (1/2) O ₂ → H ₂ O (6)

When the combustion heat of the anode off gas alone is not sufficient to maintain the reforming catalyst 22 at an appropriate temperature, the raw fuel gas is supplied via the valve V3, and the combustion represented by the above chemical reaction formula (5). Promote the reaction. If the catalyst is a plate-type catalyst, the temperature difference between the heating means (combustion catalyst) and the object to be heated (reforming catalyst) can be reduced when the reforming catalyst 22 is heated by the combustion catalyst 21. For example, a configuration in which the temperature of the combustion catalyst 21 is 710 ° C. and the temperature of the reforming catalyst 22 can be maintained at 700 ° C. is possible. Therefore, since the temperature can be set low, fuel consumption can be reduced.

  The evaporation unit 30 is a heat recovery unit 33 that recovers the heat of the combustion gas discharged from the combustion catalyst 21 of the reforming unit 20, and hydrogen gas that is discharged from the fuel cell 60 and supplied through the valve V10. A combustion catalyst 31 that combusts anode off gas as gas fuel, and a heat recovery unit 33 and an evaporation processing unit 32 that evaporates the raw water supplied from the water supply pump 14 by heating by the combustion catalyst 31.

  The valve V8 opens the flow path connecting the selective oxidation catalyst 51 and the circulation blower 13 during start-up operation (the state shown in FIG. 1), and opens the flow path connecting the selective oxidation catalyst 51 and the valve V9 during normal operation. And In the valve V9, since the carbon monoxide concentration is not sufficiently reduced immediately after the start-up operation is shifted, the flow path connecting the valve V8 and the valve V10 is opened (referred to as the “first state” of the valve V9). Control is performed so that the reformed gas is not supplied to the fuel cell 60, and when the carbon monoxide concentration of the hydrogen-containing gas sent from the selective oxidation catalyst 51 becomes a predetermined value or less, the valve V8 and the anode 61 of the fuel cell 60 are turned on. The flow path to be connected is in an open state (referred to as “second state” of the valve V9). When the valve V9 is in the first state, the valve V10 opens the flow path connecting the valve V9 and the combustion catalyst 31. On the other hand, when the valve V9 is in the second state, the valve V10 opens the flow path connecting the anode 61 and the combustion catalyst 31 so that the anode off gas is supplied to the combustion catalyst 31.

Operation Control Method Hereinafter, the operation of each element will be described together with the operation control method of the fuel cell system shown in FIG. Below, the case where methane is used as source gas is demonstrated. First, the operation control method at the time of starting is demonstrated. The original valve V6 is opened, and the valve V4 is controlled so that the gas flow rate is constant, and the air from the air blower 12 is circulated through the burner 11, the combustion catalyst 21, and the heat recovery unit 33.

  Methane is supplied to the burner 11 from the valve V1, and the burner 11 is ignited to generate high-temperature (800 to 850 ° C.) combustion gas. The high-temperature combustion gas from the burner 11 is circulated to the combustion catalyst 21 and the heat recovery unit 33, and the combustion catalyst 21 and the heat recovery unit 33 are heated using the high-temperature combustion gas as a heat medium (first heating step). . The heat of the combustion catalyst 21 is conducted to the reforming catalyst 22, and the reforming catalyst 22 is heated.

  When the temperature of the combustion catalyst 21 is measured and the ignition temperature (600 to 700 ° C.) of methane is reached, methane serving as the raw fuel gas is supplied to the combustion catalyst 21 from the valve V3 and burned (second heating) Process). At this time, the combustion catalyst 21 generates heat by a combustion reaction (shown by the chemical reaction formula (5)). The temperature rise of the reforming catalyst 22 is further accelerated by the generated heat. Along with the heating of the reforming catalyst 22 by the combustion heat of methane, the heating of the combustion catalyst 21 by the burner 11 from the start-up is continued, and the combustion catalyst 21 is heated until the reforming catalyst 22 reaches the reforming treatment temperature.

  The valve V8 opens the flow path connecting the selective oxidation catalyst 51 and the circulation blower 13 during the start-up operation and the stop operation (the state shown in FIG. 1). The circulation blower 13 is operated at an initial flow rate until the reforming catalyst 22 reaches a predetermined temperature to prevent seizure of the reforming catalyst 22, and the heat of the reforming catalyst 22 is converted into the rear shift conversion catalyst 41, the selective oxidation catalyst. 51. In order to isolate the reforming catalyst 22 from oxygen in the air, nitrogen is purged at the time of stoppage, so that the circulated gas is nitrogen gas. The introduction of nitrogen for the nitrogen purge is performed through the valve V7.

  When the reforming catalyst 22 reaches a predetermined temperature (700 ° C.), the amount of circulating nitrogen gas is increased so that the temperature of the reforming catalyst 20 is maintained at the predetermined temperature, and the temperature of the reforming catalyst 22 is increased. In addition, the downstream shift catalyst 41 and the selective oxidation catalyst 51 are heated using the nitrogen gas heated in the reforming catalyst 22 as a heat medium. When the temperature of the selective oxidation catalyst 51 reaches 80 to 150 ° C., which is the selective oxidation treatment temperature, the combustion reaction in the burner 11 and the circulation of nitrogen by the circulation blower 13 are stopped. At this time, the temperature of the shift catalyst 41 is 150 to 250 ° C.

  Next, it shifts to normal operation. Hereinafter, an operation control method during normal operation will be described. During normal operation, distilled water is supplied in a gaseous state, and raw fuel gas is supplied to the reforming catalyst 22 via the valve V2. Distilled water is generated in the evaporation unit 30. First, distilled water is supplied from the water supply pump 14 to the evaporation processing unit 32 in the evaporation unit 30. Since the evaporation processing unit 32 is heated by the heat recovery unit 33 to a temperature at which distilled water can be vaporized, the distilled water supplied to the evaporation processing unit 32 is vaporized. Thereafter, the vaporized distilled water is supplied to the reforming catalyst 22. When the amount of heat of evaporation is insufficient, the insufficient amount of heat is compensated by the combustion reaction of hydrogen contained in the anode off-gas at the combustion catalyst 31. The combustion reaction in the combustion catalyst 31 adjusts the amount of heat generated by adjusting the amount of air supplied through the valve V5.

  In the reforming catalyst 22, methane is supplied to the reforming catalyst 22 so that the ratio of the supplied steam and methane falls within a predetermined range. When the raw fuel gas is supplied to the reforming catalyst 22, the reforming treatment reaction represented by the above chemical reaction formula (1) occurs.

  For the heating of the reforming catalyst 22 during normal operation, the temperature is easily controlled, the reaction can be performed at a low temperature, and a combustion catalyst 21 that is more compact than a burner is used. The supply amount of the raw fuel gas fed from the valve V3 to the combustion catalyst 21 is changed so that the temperature of the reforming catalyst 22 becomes constant.

  The reformed gas emitted from the reforming catalyst 22 is sent to the shift catalyst 41. After the shift treatment shown in the chemical reaction formula (2) is performed, air is supplied from the valve V7. The selective oxidation treatment of carbon monoxide represented by the reaction formula (3) is performed. A hydrogen-containing gas having a low carbon monoxide concentration is generated by the processing in the shift unit 40 and the selective oxidation unit 50. The shift unit 40 and the selective oxidation unit 50 perform the shift process and the selective oxidation process, and cool the catalysts 41 and 51 by the cooling units 42 and 52.

  The valve V8 is switched so that the flow path connecting the selective oxidation catalyst 51 and the valve V9 is opened at the time of transition from the startup operation to the normal operation. Moreover, since the carbon monoxide concentration in the hydrogen-containing gas is high immediately after the transition to the normal operation, the valve V9 is controlled so that the bypass line 5 connecting the valve V10 is opened (the state shown in FIG. 1). The contained gas is prevented from being supplied to the anode 61. Then, after the transition to normal operation, when the carbon monoxide concentration in the hydrogen-containing gas becomes equal to or less than a predetermined value, the valve V9 and the valve V10 are switched to open the flow path connecting the valve V8 and the anode 61 to the anode 61. The supply of hydrogen-containing gas is started.

  Simultaneously with the supply of the hydrogen-containing gas to the anode 61, the supply of air to the cathode 62 is started, and the supply of distilled water to the heat recovery unit 63 via the water circulation pump 7 is started. Promote electrochemical reactions. The electricity generated in the fuel cell 60 is taken out to the outside. In the heat exchanging unit 70, water for hot water supply is heated using the heated distilled water discharged from the heat recovery unit 63 as a heat source and stored in the water storage tank 19. The hot water in the water storage tank 19 is taken out and used as necessary. For example, it is used as household bath water. The hot water in the water storage tank 19 is heated by the burner 11 as necessary.

Hereinafter, a method for stopping the operation of the fuel reformer 1 and the fuel cell 60 will be described. When stopping the operation of the fuel reformer 1, the valves V1 and V2 are closed to stop the supply of raw fuel gas. Further, the water supply pump 14 is stopped. With the valves V9 and V10 shown in FIG. 1 and the valve V8 in the state shown in FIG. 1, nitrogen gas is introduced through the valve V7 and the circulation blower 13 is used to reform the reforming catalyst 22, the shift catalyst 41, and selective oxidation. The flow path connecting the catalyst 51 and the reforming catalyst 22 is purged with nitrogen. In the fuel cell 60, the supply of distilled water from the water circulation pump 7 is stopped. The air blower 12 operates until the temperature in the fuel reformer 1 is sufficiently lowered, and the valves V4 and V5 are opened to cool the reforming catalyst 22. When the temperature in the fuel reformer 1 is sufficiently lowered, the air blower 12 is stopped and the original valve V6 is closed.
(Second Embodiment)
FIG. 2 is a flow sheet showing the fuel cell system of the second embodiment. The same components as those in the fuel cell system according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

The desulfurization unit 15 is configured to perform a desulfurization process of the raw fuel gas supplied to the reforming catalyst 22 and the combustion catalyst 21. In the reforming unit 20, the reforming catalyst 22 is heated during the start-up operation by the heat recovery unit 23 that recovers heat from the high-temperature combustion gas generated by the combustion reaction in the burner 11. The heat recovery unit 23 heats the combustion catalyst 21 as well as the reforming catalyst 22. The reforming catalyst 22 is heated by the combustion catalyst 21 during normal operation. During normal operation, the combustion catalyst 21 is maintained at a temperature at which the reforming catalyst 22 can be reformed by the combustion reaction of the hydrogen gas that is the anode off-gas in the combustion catalyst 21. When the heat is insufficient, the fuel is adjusted by adding fuel such as methane from the valve V3. Therefore, heat is conducted from the combustion catalyst 21 to the reforming catalyst 22, and the reforming catalyst 22 is maintained at a temperature at which the reforming process can be performed.
(Third embodiment)
FIG. 3 is a flow sheet showing the fuel cell system of the third embodiment. The same components as those in the fuel cell system according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

In the fuel cell system of this embodiment, in order to reduce the temperature distribution of the reforming unit 20, the heat exchanger 83 exchanges heat between the gas discharged from the combustion catalyst 21 and the gas introduced into the combustion catalyst 21. The heat exchanger 84 exchanges heat between the gas exhausted from the reforming catalyst 22 and the gas introduced into the reforming catalyst 22. Other configurations are the same as those of the fuel cell system of the first embodiment.
(Fourth embodiment)
FIG. 4 is a flow sheet showing the fuel cell system of the fourth embodiment. The same components as those in the fuel cell system according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the fuel cell system of the present embodiment, the heat of the gas discharged from the heat recovery unit 23 and the gas introduced into the combustion catalyst 21 by the heat exchanger 85 in order to reduce the temperature distribution of the reforming unit 20. The heat exchanger 86 exchanges heat between the gas discharged from the reforming catalyst 22 and the gas introduced into the reforming catalyst 22. Other configurations are the same as those of the fuel cell system of the second embodiment.

  The fuel reformer of the present invention is useful for a fuel cell using hydrogen gas as a fuel. Since the start-up time until the hydrogen-containing gas is supplied can be shortened, quick fuel is required when necessary, especially in applications where the hydrogen-containing gas is supplied to household fuel cells, etc. Can be supplied and is useful.

The figure which shows the flow sheet of the fuel cell system of 1st Embodiment. The figure which shows the flow sheet of the fuel cell system of 2nd Embodiment. The figure which shows the flow sheet of the fuel cell system of 3rd Embodiment. The figure which shows the flow sheet of the fuel cell system of 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel reformer 5 Bypass line 7 Water circulation pump 11 Burner 12 Air blower 13 Circulation blower (circulation means)
DESCRIPTION OF SYMBOLS 14 Water supply pump 19 Water storage tank 20 Reforming part 21 Combustion catalyst 22 Reforming catalyst 23 Heat recovery part 30 Evaporation part 31 Combustion catalyst 32 Evaporation process part 33 Heat recovery part 40 Transformation part 41 Transformation catalyst 50 Selective oxidation part 51 Selective oxidation catalyst 51 60 Fuel Cell 61 Anode 62 Cathode 63 Heat Recovery Unit

Claims (11)

  A reforming unit for reforming a raw fuel gas composed of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas by reacting with steam under a reforming catalyst, and a reforming process supplied from the reforming unit A shift unit that converts the carbon monoxide gas in the reformed gas into carbon dioxide gas under a shift catalyst, and a shift gas supplied from the shift unit under the selective oxidation catalyst. A selective oxidation unit that selectively oxidizes carbon monoxide gas in the shift treatment gas, a combustion catalyst that heats the reforming catalyst, and a first heating unit that supplies heat to the combustion catalyst; When the temperature of the combustion catalyst reaches a temperature at which the raw fuel gas can be combusted, the raw fuel gas is supplied to the combustion catalyst, and the heat generated during combustion of the raw fuel gas in the combustion catalyst Modified touch The fuel reformer and a second heating means for heating the.   An inert gas is circulated in the order of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst, and the heat of the reforming catalyst is supplied to the shift catalyst and the selective oxidation catalyst downstream by the inert gas. The fuel reformer according to claim 1, further comprising a circulation means for heating the shift catalyst and the selective oxidation catalyst.   The fuel reformer according to claim 1 or 2, wherein the first heating means is a burner.   A reforming unit for reforming a raw fuel gas composed of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas by reacting with steam under a reforming catalyst, and a reforming process supplied from the reforming unit A shift unit that converts the carbon monoxide gas in the reformed gas into carbon dioxide gas under a shift catalyst, and a shift gas supplied from the shift unit under the selective oxidation catalyst. A selective oxidation unit that selectively oxidizes carbon monoxide gas in the shift treatment gas and an inert gas are circulated in the order of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst, and the inert gas is circulated. A fuel reformer comprising: circulation means for supplying heat of the reforming catalyst to the downstream conversion catalyst and the selective oxidation catalyst by gas and heating the conversion catalyst and the selective oxidation catalyst. A reforming unit for reforming a raw fuel gas composed of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas by reacting with steam under a reforming catalyst, and a reforming process supplied from the reforming unit A shift unit that converts the carbon monoxide gas in the reformed gas into carbon dioxide gas under a shift catalyst, and the shift gas supplied from the shift unit under the selective oxidation catalyst A selective oxidation unit that selectively oxidizes carbon monoxide gas in the shift treatment gas; a combustion catalyst that heats the reforming catalyst; and a first heating unit that supplies heat to the combustion catalyst. A fuel reformer operation control method comprising:
A first heating step of heating the combustion catalyst by a first heating means;
After the temperature of the combustion catalyst reaches a temperature at which the raw fuel gas can be combusted, the raw fuel gas is supplied to the combustion catalyst, and the reforming catalyst is generated by heat generated during combustion of the raw material gas in the combustion catalyst And a second heating step for heating the fuel reforming apparatus.   The operation control method for a fuel reformer according to claim 5, wherein, in the second heating step, the combustion catalyst is heated by the first heating means together with the heating of the reforming catalyst.   An inert gas is circulated in the order of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst, and heat of the reforming catalyst is circulated to the downstream shift conversion catalyst and the selective oxidation catalyst by circulation of the inert gas. The operation control method for a fuel reformer according to claim 5 or 6, further comprising a step of supplying and heating the shift catalyst and the selective oxidation catalyst. A reforming unit for reforming a raw fuel gas composed of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas by reacting with steam under a reforming catalyst, and a reforming process supplied from the reforming unit A shift unit that converts the carbon monoxide gas in the reformed gas into carbon dioxide gas under a shift catalyst, and the shift gas supplied from the shift unit under the selective oxidation catalyst An operation control method for a fuel reformer including a selective oxidation unit that selectively oxidizes carbon monoxide gas in a shift treatment gas,
An inert gas is circulated in the order of the reforming catalyst, the shift catalyst, and the selective oxidation catalyst, and heat of the reforming catalyst is circulated to the downstream shift conversion catalyst and the selective oxidation catalyst by circulation of the inert gas. A method for controlling the operation of the fuel reformer, comprising: supplying and heating the shift catalyst and the selective oxidation catalyst.   A fuel reformer according to any one of claims 1 to 3, a fuel cell that uses hydrogen-containing gas produced by the fuel reformer as fuel, and heat generated by power generation of the fuel cell as a heat source A fuel cell system comprising: a storage tank for storing heated water, wherein the first heating means is also means for heating water in the storage tank. A fuel reformer, a fuel cell that uses hydrogen-containing gas generated by the fuel reformer as a fuel, and a water storage tank that stores water heated by using heat generated by power generation of the fuel cell as a heat source; An operation control method for a fuel cell system comprising:
The fuel reformer includes a reforming unit that reforms a raw fuel gas made of hydrocarbons into a gas containing hydrogen gas and carbon monoxide gas by reacting with steam under a reforming catalyst; and the reforming unit A reforming section for transforming the reforming process gas supplied from the reforming catalyst by transforming carbon monoxide gas in the reforming process gas into carbon dioxide gas under the shift catalyst, and the transforming process gas supplied from the shift section A selective oxidation unit that selectively oxidizes carbon monoxide gas in the shift gas under a selective oxidation catalyst, a combustion catalyst that heats the reforming catalyst, and heat is supplied to the combustion catalyst First heating means,
A first heating step of heating the combustion catalyst by a first heating means;
After the temperature of the combustion catalyst reaches a temperature at which the raw fuel gas can be combusted, the raw fuel gas is supplied to the combustion catalyst, and the reforming catalyst is generated by heat generated during combustion of the raw material gas in the combustion catalyst A second heating step for heating
And a step of heating the water in the water storage tank by a first heating means.   The operation control method for a fuel cell system according to claim 10, wherein in the second heating step, the combustion catalyst is heated by the first heating means together with the heating of the reforming catalyst.

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