DESCRIPTION

REFORMING SYSTEM

TECHNICAL FIELD

[OOOl] The present invention relates to a reforming system for generating reformed gas, which contains hydrogen, by reacting gaseous raw material for reforming with water.

BACKGROUND ART

[0002] Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2005-71,934 discloses a conventional fuel-cell system, which comprises a reforming apparatus for generating hydrogen-rich reformed gas from reforming raw material; and a fuel cell. When turning off the operating conventional fuel-cell system, both of outlet-side valve and inlet-side valve are closed, thereby keeping the resulting hydrogen-rich reformed gas, which remains in the reforming apparatus, inside the reforming apparatus.

[0003] Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2004-307,236 discloses a system for producing hydrogen. When turning off the conventional system, the raw-material-gas supply andwater supplyto the reformer are turnedoff, and then the inlet-side valve is opened to supply raw-material gas to the reformer and CO transformer upon the temperatures of the reformer and CO transformer becoming a predetermined temperature or less, thereby sealing the resulting reformed gas therein.

[ 0004 ] However, the fuel-cell system disclosed in Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2005-71,934, and the hydrogen-producing system disclosed in Japanese Unexamined Patent Publication (KOKAI) Gazette No. 2004-307,236 might be associated with such a fear that the remaining heat of the reforming

apparatus and reformer has turned water, which remains in the reforming apparatus and reformer, into water vapor excessively, and the resultant excessive vaporization of the remaining water has accordingly increased the inner pressure of the reforming apparatus and reformer superfluously.

DISCLOSURE OF THE INVENTION

[0005] The present invention has been developed in view of the aforementioned circumstances. It is therefore an object of the present invention to provide a reforming system, which can inhibit the inner pressure of reforming apparatus from increasing excessively, that is, which can be made without ever setting the pressure resistance of reforming apparatus superfluously high.

[0006] A reforming system according to a first aspect of the present invention comprises: a reforming apparatus comprising a reformer for generating reformed gas containing hydrogen by means of reacting gaseous raw material for reforming with water; an inlet-side valve being disposed on an upstream side with respect to the reforming apparatus, thereby supplying the gaseous raw material for reforming to the reformer of the reforming apparatus ; an outlet-side valve being disposed on a downstream side with respect to the reforming apparatus, thereby discharging the reformed gas being generated at the reformer of the reforming apparatus out of the reforming apparatus; and a controller for controlling the inlet-side valve and the outlet-side valve; when the controller carries out reforming-operation turning-off procedure for turning off the reforming apparatus's

reforming operation after operating the reforming apparatus to generate the reformed gas; the controller carrying out closing procedure for closing both of the inlet-side valve and the outlet-side valve; and the controller carrying out opening/closing procedure in which the controller not onlymaintains the inlet-side valve' s closed state but also opens the outlet-side valve when pressure inside the reforming apparatus increases topredeterminedpressure, and inwhich the controller thereafter closes the outlet-side valve.

[0007] The controller operates the reforming apparatus to generate reformed gas, which contains hydrogen. Thereafter, the controller turns off the reforming apparatus's reforming operation. Specifically, the controller turns off the supply of gaseous raw material for reforming and water to the reforming apparatus. When the reformer of the reforming apparatus has remaining heat, that is, when the reformer is put in high-temperature state, upon turning off the reforming apparatus's reforming operation, the controller carries out closing procedure in which the controller closes both of the inlet-side valve and the outlet-side valve. Accordingly, the controller makes it possible to inhibit the entire reformed gas, which has been generated within the reforming apparatus and which contains hydrogen, from being discharged to the outside of the reforming apparatus. In other words, the controller enables the reformed gas, which contains hydrogen, to remain inside the reforming apparatus. Consequently, it is possible to inhibit a catalyst, which is loaded inside the reformer of the reforming apparatus, from being degraded by oxidation. Therefore, it is possible for the catalyst to exhibit improved durability.

[0008] Note herein that, even when the controller turns off the reforming apparatus's reforming operation, pressure inside the reforming apparatus increases because the reformer' s remaining heat turns liquid-phased water, which remains in the reforming apparatus, into water vapor. When the pressure inside the reforming apparatus increases to predetermined pressure, the controller carries out opening/closing procedure in which the controller opens the outlet-side valve while maintaining the inlet-side valve's closed state and thereafter closes the outlet-side valve. As a result, the controller can inhibit the pressure inside the reforming apparatus from increasing excessively, because the controller operates the outlet-side valve to let out the increasing pressure inside the reforming apparatus through it. Hence, it cannot be necessarily required that the reforming apparatus be provided with superfluously high pressure-resistant construction.

[0009] However, when the controller turns off the reforming apparatus' s reforming operation, the cooling of the high-temperature state reforming apparatus develops gradually. In this instance, there might be a fear that such a phenomenon occurs that the reforming apparatus's inside turns into excessively negative-pressure state, because the once generated water vapor condenses to turn into liquid-phased water. If such is the case, as the reforming apparatus's inside turns into excessively negative-pressure state, there might arise such a fear that outside air, which contains oxygen, goes into the inside of the reforming apparatus superfluously. Then, the constituent materials, such structural material, like stainless steel, and catalyst, for instance, that make the inside of the reforming apparatus might be degraded by oxidation. For example,

oxygen that is contained in the outside air might adversely affect a built-in catalyst, which is incorporated into the reforming apparatus or which is loaded on a support being disposed therein, to undergo degradation by oxidation . In order to inhibit the adverse effect from occurring, it might be preferable to employ an expensive special valve, which exhibits strong closability and high pressure-resistance sealability, for both of the inlet-side valve and outlet-side valve, respectively. However, such a special valve is not advantageous because of its fairly higher cost, and accordingly is not preferable from the viewpoint of reducing the cost of reforming system.

[ 0010 ] Taking the above-described possible drawbacks into consideration, the reforming system according to the first aspect of the present invention can actively keep the reformed gas, which contains hydrogen, remaining inside the reforming apparatus when the controller turns off the reforming apparatus's reforming operation . Accordingly, even when the reforming apparatus is cooled to condense water vapor into liquid-phased water, the present reforming system according to the first aspect can inhibit such a phenomenon that the reforming apparatus's inside turns into excessively negative-pressure state from occurring . Consequently, the present reforming system according to the first aspect can prohibit outside air, which contains oxygen, from going into the inside of the reforming apparatus. Moreover, even if the reforming apparatus's inside should have been put into excessively negative-pressure state to allow outside air, which contains oxygen, to go into the inside of the reforming apparatus, it is possible to inhibit the outside air fromexisting as oxygen inside the reforming

apparatus because hydrogen, which remains inside the reforming apparatus reacts with oxygen in the outside air to consume oxygen in the outside air. In addition, nitrogen gas, which occupies a major part of the outside air, that is, a major part of the outside air other than the consumed oxygen, prohibits the reforming apparatus's inside from turning into excessively negative-pressure state. Itis for this reason that it is possible to inhibit a catalyst, which is loaded inside the reforming apparatus, from being degraded by oxidation so that the catalyst exhibits improved durability. Therefore, it is not at all necessary to use an expensive special valve, which exhibits strong closability and high pressure-resistance sealability, tomake both of the inlet-side valve and outlet-side valve, respectively. Thus, it is possible to make use of general valves, which exhibit ordinary sealability and whose cost is lower, to make the inlet-side valve and outlet-side valve. All in all, the present reforming system according to the first aspect makes it possible to reduce the cost of reforming system.

[OOll] In a first preferablemodifiedversion of the reforming system according to the first aspect of the present invention, when the controller carries out the closing procedure, the controller can preferably close the inlet-side valve while opening the outlet-side valve; and then can preferably close the outlet-side valve after first predetermined time has elapsed. When the controller turns off the reforming apparatus's reforming operation, the reformer is still in high-temperature state because of remaining heat. Accordingly, it is might be possible for the gaseous raw material for reforming, and water, which reside inside the reformer, to develop reforming reaction to generate hydrogen. If such is the case, gaseous

volume increases within the reformer. For example, when the gaseous raw material for reforming contains CH ₄ , the reforming reaction develops according to a chemical equation, CH ₄ + H ₂ O > 3H ₂ + CO.

That is, the total molar number of the starting materials is 2 mol before the reforming reaction, and the total molar number of the products is 4 mol after the reforming reaction. Thus, the gaseous volume increases within the reformer after the reforming reaction. Consequently, in accordance with the first preferable modified version of the present reforming system according to the first aspect, the controller carries out the closing procedure, thereby closing the inlet-side valve while opening the outlet-side valve; and then closing the outlet-side valve after first predetermined time has elapsed. Specifically, the controller retards the closing of the outlet-side valve in terms of time with respect to the closing of the inlet-side valve. Thus, it is possible for the present reforming system according to the first aspect to keep the reformed gas, which contains hydrogen exhibiting reducing ability, as much as possible inside the reforming apparatus while discharging the reformed gas. Accordingly, not only the present reforming system according to the first aspect can inhibit a catalyst, which is disposed inside the reforming apparatus, from being degraded by oxidation, but also it can cope with the increasing gaseous volume inside the reforming apparatus. Although the first predetermined time specified above depends on the specific types of reforming apparatus and outlet-side valve, it is feasible to exemplify that the first predetermined time canpreferably fall in a range of fromO.3 to 20 seconds, more preferably in a range of from 0.5 to 10 seconds, much more preferably in a range of from 1 to 5 seconds. As described above, in accordance with the

first preferable modified version, the present reforming system according to the first aspect can inhibit a catalyst, for instance, that is loaded inside the reforming apparatus from being degraded by oxidation, because it can keep the reformed gas, which contains hydrogen, as much as possible inside the reforming apparatus.

[0012] In a second preferable modified version of the reforming system according to the first aspect of the present invention, when the controller carries out the reforming-operation turning-off procedure, the controller can preferably open the inlet-side valve to charge the gaseous raw material for reforming into the reformer of the reforming apparatus after carrying out the opening/closing procedure, thereby inhibiting the pressure inside the reforming apparatus from turning into negative pressure excessively. Turning the reforming apparatus's reforming operation off associates with the reforming apparatus' s decreasing temperature. Accordingly, the pressure inside the reforming apparatus' s reformer is likelytobecome negative pressure, because water vapor, which is present inside the reforming apparatus, condenses to generate liquefied water. In view of this fact, in accordance with the second preferable modified version, the controller charges the gaseous rawmaterial for reforming into the reformer actively to inhibit the pressure inside the reformer from turning into negative pressure excessively when it carries out the reforming-operation turning-off procedure. Consequently, the present reforming system according to the first aspect can inhibit outside air from intruding into the inside of the reforming apparatus . Therefore, in manufacturing the present reforming apparatus according to the first aspect, using an expensive special valve, which exhibits strong closability and high pressure-resistance

sealability, is not at all necessarily required for making both of the inlet-side valve and outlet-side valve, respectively, but it is possible to employ general valves, which exhibit ordinary sealability and whose cost is low, for making them. Thus, the present reforming system according to the first aspect can contribute to reducing the manufacturing cost of reforming system. Note that, in the second preferable modified version, the gaseous raw material for reforming, which is to be charged into the reformer, can either be those which generate hydrogen by means of reforming reaction or those which do not generate hydrogen.

[0013] Ina thirdpreferablemodifiedversionof the reforming system according to the first aspect of the present invention, when the controller carries out the reforming-operation turning-off procedure, the controller can preferably open the inlet-side valve to charge the gaseous raw material for reforming into the reformer of the reforming apparatus after carrying out the opening/closing procedure, thereby inhibiting the pressure inside the reforming apparatus from turning into negative pressure excessively. Since hydrogen exhibits reducing ability, it is advantageous for inhibiting a catalyst, which is loaded inside the reforming apparatus, from being degraded by oxidation. Moreover, since the gaseous raw material for reforming is charged into the reformer to generate hydrogen gas actively, it is possible to prohibit the inside of the reforming apparatus from being put in excessively negative-pressure state. Therefore, the third preferable modified version not only makes it unnecessary at all to use an expensive special valve, which exhibits strong closability and high pressure-resistance sealability, to make both of the inlet-side valve and outlet-side

valve, respectively, but also makes it possible as well to make use of general valves, which exhibit ordinary sealability and whose cost is lower, to make the inlet-side valve and outlet-side valve. All in all, in accordance with the third preferable modified version, it is possible for the present reforming system according to the first aspect to contribute to reducing the cost of reforming system. [0014] A reforming system according to a second aspect of the present invention comprises: a reforming apparatus comprising a reformer for generating reformed gas containing hydrogen by means of reacting gaseous raw material for reforming with water; an inlet-side valve being disposed on an upstream side with respect to the reforming apparatus, thereby supplying the gaseous rawmaterial for reforming to the reformer of the reforming apparatus ; an outlet-side valve being disposed on a downstream side with respect to the reforming apparatus, thereby discharging the reformed gas being generated at the reformer of the reforming apparatus out of the reforming apparatus; and a controller for controlling the inlet-side valve and the outlet-side valve; the reforming apparatus further comprising: a heater for heating the reformer; an evaporator for generating water vapor to be supplied to the reformer; and a CO reducer being disposed thermally exchangeably to the evaporator and comprising a built-in catalyst for reducing CO component being contained in the reformed gas that the reformer generates; when the controller carries out reforming-operation turning-off procedure for turning off the reforming apparatus's

reforming operation after operating the reforming apparatus to generate the reformed gas; the controller keeping the heater of the reforming apparatus heating the reformer for second predetermined time to slow down the CO reducer' s temperature-decrement rate while suppressing the evaporator' s temperature decrement, thereby subjecting the built-in catalyst of the CO reducer to reducing treatment in such a state that hydrogen resides in the CO reducer.

[0015] When the reforming system according to the second aspect of the present invention carries out the reforming-operation turning-off procedure for turning off the reforming apparatus's reforming operation, the controller keeps the heater of the reforming apparatus heating the reformer for second predetermined time. Note that the second predetermined time can preferably fall in a range of from 2 to 60 minutes, more preferably in a range of from 5 to 30 minutes, for instance, but cannot necessarily be limited to these ranges. The reforming system according to the second aspect of the present invention can inhibit the evaporator of the reforming apparatus from exhibiting decreasing temperature, thereby maintaining the temperature of the evaporator as it is as long as possible. Note that the reforming system according to the second aspect of the present invention involves such a form that the evaporator exhibits increasing temperature as well. Eventually, the reforming system according to the second aspect of the present invention slows down the temperature-decrement rate that the evaporator of the reforming apparatus shows, thereby keeping the temperature of the evaporator at the recovery temperature of the built-in catalyst, which is loaded inside the CO reducer,

satisfactorily. Under the circumstances, since hydrogen resides in the CO reducer, the residing hydrogen reduces the built-in catalyst, which is loaded inside the CO reducer. Thus, the reforming system according to the second aspect of the present invention can inhibit the built-in catalyst from being degraded by oxidation, and thereby the built-in catalyst shows improved durability. As for the CO reducer, it is possible to exemplifyCO-oxidizing removers that remove CO, which reformed gas contains, by means of oxidation with oxygen. [OOlβ] A reforming system according to a third aspect of the present invention comprises: a reforming apparatus comprising a reformer for generating reformed gas containing hydrogen by means of reacting gaseous raw material for reforming with water; an inlet-side valve being disposed on an upstream side with respect to the reforming apparatus, thereby supplying the gaseous rawmaterial for reforming to the reformer of the reforming apparatus; an outlet-side valve being disposed on a downstream side with respect to the reforming apparatus, thereby discharging the reformed gas being generated at the reformer of the reforming apparatus out of the reforming apparatus; and a controller for controlling the inlet-side valve and the outlet-side valve; the reforming apparatus further comprising: a heater for heating the reformer; an evaporator for generating water vapor to be supplied to the reformer; and a CO reducer being disposed thermally exchangeably to the evaporator and comprising a built-in catalyst for reducing CO component being contained in the reformed gas that the reformer generates;

when the controller carries out reforming-operation turning-off procedure for turning off the reforming apparatus's reforming operation after operating the reforming apparatus to generate the reformed gas; the controller keeping the reforming apparatus's reforming operation going on for third predetermined time after turning off fuel cell's electric-power generation operation to slow down the CO reducer' s temperature-decrement rate while suppressing the evaporator' s temperature decrement, thereby subjecting the built-in catalyst of the CO reducer to reducing treatment in such a state that hydrogen resides in the CO reducer.

[0017] Before the reforming system according to the third aspect of the present invention carries out the reforming-operation turning-off procedure for turning off the reforming apparatus's reforming operation, it has the controller keep the reforming apparatus's reforming operation going on for third predetermined time. Note that the third predetermined time can preferably fall in a range of from 2 to 60 minutes, more preferably in a range of from 5 to 30 minutes, for instance, but cannot necessarily be limited to these ranges. Accordingly, the present reforming system according to the third aspect enables the controller to inhibit the evaporator of the reforming apparatus from exhibiting decreasing temperature. Consequently, the evaporator keeps exhibiting temperature as high as possible. Note that such a form that the evaporator exhibits increasing temperature is involved as well in the present reforming system according to the third aspect. Eventually, the present reforming systemaccording to the third aspect enables the CO reducer of the reforming apparatus to show slowing-down

temperature-decrement rate so that the evaporator exhibits temperature that is kept at the recovery temperature of the built-in catalyst, which is loaded inside the CO reducer, satisfactorily. Under the circumstances, since the CO reducer holds hydrogen that resides therein, the built-in catalyst, which is loaded inside the CO reducer, is subjected to reducing treatment making use of the residing hydrogen. Accordingly, the present reforming system according to the second aspect makes it possible to inhibit the built-in catalyst from being degraded by oxidation, and consequently it enables the built-in catalyst to show improved durability.

[0018] A reforming systemaccording to a fourth aspect of the present invention comprises: a reforming apparatus comprising a reformer for generating reformed gas containing hydrogen by means of reacting gaseous raw material for reforming with water; an inlet-side valve being disposed on an upstream side with respect to the reforming apparatus, thereby supplying the gaseous rawmaterial for reforming to the reformer of the reforming apparatus ; an outlet-side valve being disposed on a downstream side with respect to the reforming apparatus, thereby discharging the reformed gas being generated at the reformer of the reforming apparatus out of the reforming apparatus; and a controller for controlling the inlet-side valve and the outlet-side valve; the reforming apparatus further comprising: a heater for heating the reformer; an evaporator for generating water vapor to be supplied to the reformer; and a CO reducer being disposed thermally exchangeably to the evaporator and comprising a built-in catalyst

for reducing CO component being contained in the reformed gas that the reformer generates; when the controller carries out reforming-operation turning-off procedure for turning off the reforming apparatus's reforming operation after operating the reforming apparatus to generate the reformed gas; the controller operating fuel cell to generate electric power in low output range for fourth predetermined time to slow down the CO reducer's temperature-decrement rate while maintaining the reforming apparatus's reforming operation, thereby subjecting the built-in catalyst of the CO reducer to reducing treatment in such a state that hydrogen resides in the CO reducer.

[0019] Before the reforming system according to the fourth aspect of the present invention carries out the reforming-operation turning-off procedure for turning off the reforming apparatus's reforming operation, the controller keeps fuel cell operating to generate electric power in low output range for fourth predetermined time while keeping the reforming apparatus's reforming operation going on. Note that the fourth predetermined time can preferably fall in a range of from 1 to 60 minutes, more preferably in a range of from 5 to 30 minutes, for instance, but cannot necessarily be limited to these ranges. On this occasion, since the controller keeps the reforming apparatus operating to carry out the reforming operation, it is possible to inhibit the evaporator of the reforming apparatus from exhibiting decreasing temperature, thereby maintaining the temperature of the evaporator as high as possible. Note that the present reforming system according to the fourth aspect involves such a form that the evaporator exhibits increasing

temperature as well. Accordingly, it is possible for the present reforming system according to the fourth aspect to slow down the temperature-decrement rate that the CO reducer of the reforming apparatus shows, thereby keeping the temperature of the CO reducer at the recovery temperature of the built-in catalyst, which is loaded inside the CO reducer, satisfactorily. Under the circumstances, since hydrogen resides in the CO reducer, the residing hydrogen reduces the built-in catalyst, which is loaded inside the CO reducer. Consequently, it is possible for the present reforming system according to the fourth aspect to inhibit the built-in catalyst from being degraded by oxidation, and thereby the built-in catalyst shows improved durability. Moreover, since the reformed gas is supplied to the fuel cell' s fuel electrode (i.e. , anode or negative electrode) as anode gas when the controller operates the fuel cell in low output range, it is possible for the present reforming system according to the fourth aspect not only to contribute to removing liquid-phased water inside the fuel cell but also to contribute to inhibiting flooding from occurring upon re-operating the fuel cell to generate electric power subsequently.

[0020] The reforming system according to the second, third or fourth aspect of the present invention can preferablybemodified as follows : when the controller carries out the reforming-operation turning-off procedure, the controller can preferably flow gas for cooling into the heater of the reforming apparatus, which is heating the reformer thereof. That is, in the preferably modified version, the gas for cooling (i.e., air, for instance) cools down the reformer of the reforming apparatus actively. Accordingly, this preferably modified version can keep the reforming apparatus from cooling

gradually. Consequently, this preferably modified version can inhibit the reforming apparatus from being held at high temperature for a long period of time. Therefore, this preferably modified version can prevent the reforming apparatus' s constituent materials from degrading. For example, when alloy steel, such as stainless steel, is employed as one of the reforming apparatus's constituent materials, this preferably modified version can inhibit the alloy steel from being held in temperature range at around the brittle temperature (e.g., 475 ⁰ C). for a long period of time. Hence, this preferably modified version can operate to prevent the reforming apparatus from undergoing high-temperature degradation, such as the 475-°C embrittlement, advantageously.

[002l] As described above, the reforming system according to the first, second, third or fourth aspect of the present invention operates to carry out : the closing procedure; and the opening/closing procedure; when turning off the reforming apparatus's reforming operation. In the closing procedure, the controller closes both of the inlet-side valve and outlet-side valve. In the opening/closing procedure, the controller not only maintains the inlet-side valve' s closed state (or keeps the inlet-side valve being closed) , but also opens the outlet-side valve when pressure inside the reforming apparatus increases to predetermined pressure and thereafter closes the outlet-side valve. As a result, the reforming system according to the first, second, third or fourth aspect of the present invention can operate advantageously to inhibit the reforming apparatus's inner pressure from increasing excessively after turning off the reforming apparatus's reforming operation. Thus, it is for this reason that the reforming apparatus cannot be

providedwith superfluous pressure resistance, and that the reforming apparatus can be made at reduced cost.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] A more complete appreciation of the present invention and many of its advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings and detailed specification, all of which forms a part of the disclosure.

[0023] Fig.1 is directed to a reforming system according to Example No.1 of the present invention, and illustrates the present reforming system in block diagram.

[0024] Fig.2 is directed to the present reforming system according to Example No. 1, and illustrates a major portion of the reforming system in block diagram.

[0025] Fig.3 is directed to a reforming system according to Example No. 2 of the present invention, and illustrates procedures that a controller, which makes the reforming system, executes when it turns off a reforming apparatus, which also makes the reforming apparatus, in timing chart.

[0026] Fig.4 is directed to a reforming system according to Example No. 3 of the present invention, and illustrates procedures that a controller, which makes the reforming system, executes when it turns off a reforming apparatus, which also makes the reforming apparatus, in timing chart.

[0027] Fig.5 is directed to a reforming system according to Example No. 8 of the present invention, and illustrates procedures that a controller, which makes the reforming system, executes when it turns off a reforming apparatus, which also makes the reforming apparatus,

in timing chart.

[θO28] Fig.6 is directed to a reforming system according to Example No. 9 of the present invention, and illustrates procedures that a controller, which makes the reforming system, executes when it turns off a reforming apparatus, which also makes the reforming apparatus, in timing chart.

[0029] Fig.7 is directed to a reforming system according to Example No.10 of the present invention, and illustrates a reforming apparatus, which makes the reforming apparatus, in cross sectional diagram. BEST MODE FOR CARRYING OUT THE INVENTION

[θO3θ] Having generally described the present invention, a further understanding can be obtained by reference to the specific preferred embodiments which are provided herein for the purpose of illustration only and not intended to limit the scope of the appended claims.

[003l] Hereinafter, specific examples according to the present invention will be described with reference to the accompanying drawings.

[0032] (Example No. 1)

[0033] A reforming system according to Example No. 1 of the present invention will be hereinafter described in detail with reference to Figs. 1 and 2. The present reforming system according to Example No. 1 is applied to making a fuel-cell electric-power generating system. A fuel cell 1 shown in Fig .1 comprises a plurality ofmembrane electrode assemblies 13, which are assembled or stacked one after another. As canbe seen from Fig.1, themembrane electrode assemblies 13 comprise a solid polymer membrane 10, a fuel electrode 11, and an oxidizing-agent electrode 12, respectively. The solid polymer membrane 10 is made from polymeric material that exhibits protonic

conductivity, and is held between the fuel electrode 11 and the oxidizing-agent electrode 12 in the thickness-wise direction of the membrane electrode assembly 13. As for the material for the solid polymer membrane 10, it is possible to exemplify fluorocarbon resin, such as perfluorosulufonic acid resin, for instance; or hydrocarbon resin. The fuel cell 1 can be made in such a manner that a plurality of sheet-shaped membrane electrode assemblies 13 are laminated one after another in the thickness-wise direction; or can be made in such a manner that a plurality of tube-shaped membrane electrode assemblies 13 are disposed one after another. Note that, when stainless steel is employed tomake a reforming apparatus, the present reforming systemaccording to Example No .1 can advantageously inhibit the embrittlement of stainless steel, which occurs when being held at a temperature of from 400 to 900 °C for a long period of time, for instance, from occurring. Moreover, when stainless steel is employed to make a reforming apparatus, the present reforming system according to Example No. 1 can advantageously prevent the sensitization of stainless steel, which is likely to arise when being held at a temperature of from 500 to 850 °C, for instance, from arising. [0034] As illustrated in Figs . land 2, the present reforming system comprises a reforming apparatus 2, which comprises a combuster 30, a reformer 34, an evaporator 36, a CO-oxidizing remover 37 (i.e., the claimed CO reducer) , and cylindrical combustion passages 32, 33 and 35. The combuster 30 is provided with a combustion burner so as to function as a heater. The reformer 34 is heated by the combuster 30. The evaporator 36 is formed as a ring shape, and is disposed around the outer periphery of the reformer 34. The CO-oxidizing remover 37 is formed as a ring shape, and is disposed

around the outer periphery of the evaporator 36. The reformer 34 is formed as a cylindrical shape that possesses an imaginary central axial line being disposed parallelly to the vertical direction, and reforms gaseous raw material for reforming to generate reformed gas. The reformer 34 is provided with the cylindrical combustion passage 32, which faces the combuster 34. The cylindrical combustion passage 33 is disposed coaxially with the cylindrical combustion passage 32 so as to surround the outer periphery of the reformer 34. The cylindrical combustion passage 35 is disposed on the outer side of the cylindrical combustion passage 33 coaxially with it so as to communicate with it. Moreover, a cylindrical heat insulator 31 is disposed between the cylindrical combustion passage 33 and the cylindrical combustion passage 35 coaxially with them. In addition, the evaporator 36, which evaporates raw-material water, is disposed coaxially with the cylindrical combustion passage 35 so as to surround it. The CO-oxidizing remover 37 (or might be hereinafter referred to as "selective CO oxidizer" whenever appropriate, if necessary) is disposed around the evaporator 36 coaxially with it in a manner neighboring on it . Therefore, the evaporator 36 and the CO-oxidizing remover 37 are disposed heat transmissibly to each other, that is, they can carry out heat exchange between them. Note herein that it is allowable to dispose the evaporator 36 and the CO-oxidizing remover 37 non-coaxially with each other. In short, it suffices that the evaporator 36 and the CO-oxidizing remover 37 can be disposed heat exchangeably to each other.

[0035] As illustrated in Figs. 1 and 2, the reformer 34 is further provided with an inner passage 34i, an outer passage 34p, and a turnaround 34m. The reformer 34, which is heated by the combuster

30, heats the evaporator 36 in turn. Since the cylindrical CO-oxidizing remover 37 is disposed around the evaporator 36 so as to surround the evaporator 36' s outer periphery, the evaporator 36' s outer periphery and the CO-oxidizing remover 37' s inner periphery neighbor on each other heat exchangeably. During the reforming apparatus 2's reforming operation, the CO-oxidizing remover 37 exhibits higher temperature than the evaporator 36, from which liquid-phased water evaporates, does in general . Accordingly, the CO-oxidizing remover 37 gives heat to the evaporator 36. Note that the CO-oxidizing remover 37' s outer periphery is covered with a cylindrical heat-insulating material 39 (or a so-called heat insulator) , which surrounds the CO-oxidizing remover 37 in order to keep it warm. However, as shown in Fig. 2, of the CO-oxidizing remover 37' s parts, a part at around an inlet 37i to which reformed gas is supplied via a later-described CO shifter 5 is not covered with the heat-insulating material 39 at all. Consequently, the heat-insulating material 39 is provided with a bottom end 39u, which does not get to the inlet 37i. A major reason for such an arrangement is for cooling down the reformedgas, because the reformed gas exhibits a slightly higher temperature than the activation temperature of a later-described built-in catalyst 37e, which is loaded inside the CO-oxidizing remover 37.

[0036] The reformer 34 is providedwith a support onwhich thebuilt-in reforming catalyst 34e for facilitating reforming reaction is loaded. For example, the built-in reforming catalyst 34e comprises nickel-system catalyst, or ruthenium-system catalyst . Althoughthe built-in reforming catalyst 34e usually exhibits an activation temperature that falls in a range of from 300 to 800 ⁰ C in general,

the activation temperature range, which the built-in reforming catalyst 34e exhibits, is not necessarily limited to such a range. However, when the reformer 34 exhibits temperature that deviates greatly from the activation temperature that the built-in reforming catalyst 34e exhibits, there might be a fear that the reformer 34 produces impaired reforming reaction. The reformer 34 uses gaseous rawmaterial for reforming andwater vapor to carry out steam reforming based on chemical equation (1) set forth below, thereby generating reformed gas that contains hydrogen. Note that the resulting reformed gas contains carbon monoxide as well. Also note that the reformer 34 produces shifting reaction based on chemical equation (2) set forth below.

[0037] Moreover, as illustrated in Figs. 1 and 2, the reforming apparatus 2 further comprises a heat exchanger 4, a CO shifter 5, and a warming-up unit 47. The heat exchanger 4 is disposed under the reformer 34. The CO shifter 5 is disposed under the heat exchanger 4, thereby functioning as a CO purifier. The warming-up unit 47 is disposed between the heat exchanger 4 and the CO shifter 5, and is providedwith an electric heater . Thus, in the resultant reforming apparatus 2, the heat exchanger 4 is disposed on a downstream side with respect to the evaporator 36, and the CO shifter 5 is disposed on a downstream side with respect to the heat exchanger 4.

[0038] The CO shifter 5 facilitates shifting reaction using water vapor based on chemical equation (2) set forth below, thereby reducing CO that is contained in reformed gas. The CO shifter 5 is provided with a support on which a built-in shifting catalyst 5e is loaded. For example, the built-in shifting catalyst 5e comprises copper-zinc-system catalyst. Although the built-in shifting

catalyst 5e usually exhibits an activation temperature that falls in a range of from 160 to 300 °C in general, the activation temperature range, which the built-in shifting catalyst 5e exhibits, is not necessarily limited to such a range. However, when the CO shifter 5 exhibits temperature that deviates greatly from this activation temperature range that the built-in shifting catalyst 5e exhibits, there might be such a fear that the CO shifter 5 produces impaired shifting reaction so that the CO shifter 5 purifies CO insufficiently. Although the concentration of CO, which is contained in reformed gas being purified at the CO shifter 5, depends on the types of gaseous raw material for reforming, it falls in a range of from 0.01 to 1% by mol in general. However, the CO concentration is not necessarily limited to those which fall in such a concentration range. The CO shifter 5 is further provided with a passage 5i, a passage 5v, and a turnaround 5m. Moreover, a purifying passage 400 connects between the CO shifter 5's outlet 5p and an oxidizing-air passage 75 by way of a second confluence M2.

[0039] The CO-oxidizing remover 37 is disposed on a downstream side with respect to the CO shifter 5, thereby facilitating selective oxidizing reaction. The selective oxidizing reaction is for reducing CO by selectively oxidizing CO out of reformed gas, which is purified at the CO shifter 5 and which contains CO as well as H, based on chemical equation (3) set forth below. The CO-oxidizing remover 37 is provided with a support on which a built-in CO-oxidizing catalyst 37e is loaded. For example, the built-in CO-oxidizing catalyst 37e comprises noble-metal-system catalyst, such as ruthenium-system catalyst, platinum-system catalyst and platinum-ruthenium-system catalyst; and the support is made of

ceramic, such as alumina. The built-in CO-oxidizing catalyst 37e usually exhibits an activation temperature that falls in a range of from 100 to 220 °C in general in oxygen-containing atmosphere. On the other hand, the built-in CO-oxidizing catalyst 37e usually exhibits an activation temperature that falls in a range of from 200 to 450 °C in general in hydrogen-containing atmosphere. However, the activation temperature ranges, which the built-in CO-oxidizing catalyst 37e exhibits, are not necessarily limited to these ranges. Note however that, when the CO-oxidizing remover 37 exhibits temperature, which deviates greatly from the activation temperature range that the built-in CO-oxidizing catalyst 37e exhibits, in oxygen-containing atmosphere, there might be such a fear that the CO-oxidizing remover 37 produces impaired selective oxidizing reaction. Although the concentration of CO, which is contained in reformed gas being purified at the CO-oxidizing remover 37 , is usually 10 ppm or less in general, it is not necessarily limited to being this value or less.

CH ₄ + H ₂ O > 3H ₂ O + CO ^••• Equation (1)

CO + H ₂ O > H ₂ + CO ₂ " ^• Equation (2)

CO + 1/2O ₂ > CO ₂ ^• " Equation (3)

[θO4θ] Since the CO shifter 5 is disposed on an upstream side with respect to the CO-oxidizing remover 37, the chemical reactions are executed in the order of chemical equation (2) and chemical equation (3) during the reforming apparatus 2's reforming operation. That is, when the reforming apparatus 2 is operating, the CO shifter 5 first produces steam reforming reaction based on chemical equation (2) , and then the CO-oxidizing remover 37 produces selectiveoxidizing reaction based on chemical equation (3) .

[004l] The present reforming system according to Example No.1 puts the CO shifter 5 in hydrogen-rich atmosphere, that is, places it under reducing condition, during the reforming apparatus 2's reforming operation. Accordingly, even when the CO shifter 5's built-in shifting catalyst 5e is oxidized, the built-in shifting catalyst 5e is likely to be reduced during the reforming apparatus 2' s reforming operation. On the other hand, the CO-oxidizing remover 37' s built-in CO-oxidizing catalyst 37e is less likely to be reduced during the reforming apparatus 2' s reforming operation alone. Under such a circumstance that oxygen is kept being supplied to the CO-oxidizing remover 37, the CO-oxidizing remover 37' s built-in CO-oxidizing catalyst 37e exhibits temperature that is present in the activation temperature range (i.e., from 100 to 220 °C, for instance) . It is said that it is unpreferable that the built-in CO-oxidizing catalyst 37e exhibits temperature that is more than

220 ⁰ C, because the degradation of the built-in CO-oxidizing catalyst 37e is likely to develop in oxidizing atmosphere when it exhibits temperature that exceeds the upper-limit temperature. However, note that changing the built-in CO-oxidizing catalyst 37e's composition results in changing the upper-limit temperature.

[0042] Next, piping that also makes the present reforming system will be hereinafter described in detail. As illustrated in Fig. 1, the present reforming system according to Example No. 1 comprises a fuel passage 62, which is disposed so as to connect to a fuel supply source 61 by way of a valve 25a. Fuel, which the fuel supply source 61 supplies, can be either gaseous fuel, or liquid fuel, or powdered fuel. Specifically, as for the fuel, it is possible to exemplify hydrocarbon fuel, and alcohol fuel. More specifically, it is

possible to exemplify processed municipal utility gas, liquefied petroleumgas (or LPG) , kerosene, methanol, dimethyl ether, gasoline, and biogas, for instance. The fuel passage 62 is provided with a combusting-fuel passage 62a, and a reforming-raw-material passage 62c. The combusting-fuel passage 62a is disposed so as to connect to the reformer 34 ^f s combuster 30 by way of the valve 25a and a pump 27a. The reforming-raw-material passage 62c is disposed so as to connect to the heat exchanger 4's inlet 4i by way of a pump 27b, a desulfurizer 62x and a valve 25b. Moreover, the present reforming system further comprises an air passage 72 (or a part of so-called oxygen supplier) , which is disposed so as to connect to an air supply source 71. The air passage 72 is provided with a combusting-air passage 73, and an oxidizing-air passage 75 (or another part of a so-called oxygen supplier) . The combusting-air passage 73 is disposed so as to connect to the reformer 34' s combuster 30 by way of a pump 27c. The oxidizing-air passage 75 is disposed so as to connect to the CO-oxidizing remover 37' s inlet 37i by way of an air-purifying filter 72x, a pump 27d and a valve 25d.

[θO43] Moreover, the present reforming system further comprises a reforming-water passage 82 (or a so-called water supplier) , which is disposed so as to connect a water tank 81 to the evaporator 36' s inlet 36i by way of a pump 27m and a valve 25m. In addition, the present reforming system further comprises an anode-gas passage 100

(or a so-called reformed-gas discharging passage) , which is disposed so as to connect the CO-oxidizing remover 37' s outlet 37p to an inlet Hi of the fuel cell l's fuel electrode 11 by way of a valve 25e

(i.e., one of the claimed outlet-side valve). As shown in Figs. 1 and 2, the anode-gas passage 100 is provided with a pressure sensor

105, pressure detecting means for detecting pressure Pl inside the reforming apparatus 2. Note that the CO-oxidizing remover 37' s outlet 37p is disposed on a height-wise upper side of the CO-oxidizing remover 37. Moreover, the present reforming system further comprises an off-gas passage 110, which connects an outlet lip of the fuel cell l's fuel electrode 11 to the reformer 34 's combuster 30 by way of a pump 25f (i.e. , another one of the claimed outlet-side valve) . The present reforming system discharges off gas, which has undergone electric-power generation reaction, through the off-gas passage 110. In addition, the present reforming system further comprises a bypass passage 150, which is disposed so as to connect the off-gas passage 110 to the anode-gas passage 100 by way of a valve 25h (i.e., still another one of the claimed outlet-side valve that communicates with the outside) .

[0044] Moreover, as shown in Fig. 1, the present reforming system according to Example No. 1 further comprises a cathode-gas passage 200, which is disposed so as to connect the air supply source 71 to an inlet 12i of the fuel cell l's oxidizing-agent electrode 12. The cathode-gas passage 200 has a pump 27k and a valve 25k. In addition, as shown in Fig. 1, the present reforming system further comprises a combusted-exhaust-gas passage 250 for emitting combusted exhaust gas, which has been combusted at the reforming apparatus 2' s reformer 34, to the outside. Moreover, the present reforming system further comprises a water-vapor passage 300, which is disposed so as to connect an outlet 36p of the reforming apparatus 2's evaporator 36 to the reforming-raw-material passage 62c by way of a first confluence Ml. The water-vapor passage 300' s top end 30Oe is connected to the evaporator 36' s outlet 36p. On the other hand, the water-vapor

passage 300' s bottom end 30Of is connected to the first confluence Ml. Note that the pumps 27a, 27b, 27c, 27d, 27k and 27m function as means or element for feeding fluid, respectively.

[θO45] As illustrated in Figs .1 and 2, the present reforming system further comprises a purifying passage 400, which is disposed so as to connect the CO shifter 5's outlet 5p to the CO-oxidizing remover 37' s inlet 37i. The present reforming system flows reformed gas, which is discharged through the CO shifter 5's outlet 5p, in the purifying passage 400 upward in an arrowheaded direction W2, and then supplies it to the CO-oxidizing remover 37' s inlet 37i via the second confluence M2. For example, the discharged reformed contains not only hydrogen as a major component, that is, in an amount of 40% by mole or more, but also contains carbon monoxide. Note that the CO-oxidizing remover 37' s inlet 37i is disposed on a height-wise lower side of the CO-oxidizing remover 37.

[0046] How the present reforming system actuates the reforming apparatus 2 will be hereinafter described with reference to Fig. 1. On this occasion, the present reforming system actuates the pump 27c to supply air for combustion to the combuster 30 of the reforming apparatus 2's reformer 34 through the combusting air passage 73. Moreover, the present reforming system actuates the valve 25a and pump27a to supply gaseous fuel for combustion to the combuster 30 of the reforming apparatus 2' s reformer 34 throughthe combusting-fuel passage 62a. Thus, the present reforming system ignites the air and fuel and then heats the combuster 30. Eventually, the combuster 30 heats the reformer 34 to such a temperature that is suitable for reforming reaction, that is, to a temperature of from 600 to 800 °C, for instance. In this instance, note that not only the reformer

34 and combustion passage 35 but also the evaporator 36 and CO-oxidizing remover 37 are heated to high temperatures.

[0047] Thereafter, the present reforming system supplies reforming water (i.e., water prior to reforming reaction) to the inlet 36i of the reforming apparatus 2's evaporator 36 from the water tank 81 through the reforming-water passage 82 by way of the pump 27m and valve 25m. Then, the high-temperature reformer 36 turns the reforming water into water vapor. The generated water vapor comes at the first confluence Ml from the evaporator 36' s outlet 36p via the water-vapor passage 300. The first confluence Ml is a region at which the water vapor or condensed water, which flows in the water-vapor passage 300, and the reforming raw material, which flows in the reforming-raw-material passage 62c, flow together. In the meantime, the present reforming system actuates the valve 25a, pump 27b and valve 25b to supply the reforming raw material to the heat exchanger 4's inlet 4i via the desulfurizer 62x, reforming-raw-material passage 62c and first confluence Ml. At the confluence Ml, the reforming raw material, which flows in the reforming-raw-material passage 62c, and the water vapor, which flows in the water-vapor passage 300, flow together, and are thereby mixed. The confluent mixture fluid is supplied to the heat exchanger 4's inlet 4i.

[0048] Themixture fluidpasses through a low-temperature-side first passage 4a of the heat exchanger 4. At this moment, the mixture fluid and the high-temperature reformed gas, which flows through a high-temperature-side second passage 4c of the heat exchanger 4, undergo heat exchange. Accordingly, the mixture fluid, which is prior to reforming reaction, is heated. The heated mixture fluid

flows into the reformer 34' s outer passage 34p to flow in the arrowheaded direction Al, and then flows into the reformer 34' s inner passage 34i via the turnaround 34mto flow in the arrowheaded direction A2. On this occasion, the mixture fluid, in which the water vapor or condensed water and the reforming raw material are mixed, is turned into hydrogen-rich reformed gas by means of the reforming reaction as set forth in chemical equation (1) above. Note that the resulting reformed gas also contains carbon monoxide.

[0049] Moreover, the high-temperature reformed gas, which has undergone the reforming reaction, flows into the heat exchanger 4 from the reformer 34. Specifically, the high-temperature reformed gas passes the high-temperature-side second passage 4c of the heat exchanger 4 via the reformer 34, and it thereby heats the mixture fluid, which flows in the low-temperature-side first passage 4a of the heat exchanger 4. In addition, the reformed gas flows into the inside of the CO shifter 5 through the CO shifter 5's inlet 5i via the warming-up unit 47. The CO shifter 5 carries out the shift reaction using water vapor as set forth in chemical equation (2) above. Thus, the CO shifter 5 reduces carbon monoxide, which is contained in the reformed gas, and it thereby purifies the reformed gas .

[0050] Moreover, the reformedgas, whichispurifiedbytheCOshifter 5, flows out of the CO shifter 5' s outlet 5p to flow in the arrowheaded direction W2 via the purifying passage 400, and then comes at the second confluence M2. In addition, the reformed gas, and oxidizing air, which flows in the oxidizing-air passage 75 (or a so-called oxygen supplier), flow together at the second confluence M2. Note that that the oxidizing air makes a so-called oxygen component, that

is, air for selective oxidation being used for selective oxidation reaction which the CO-oxidizing remover 37 carries out. Thus, the second confluence M2 is a region at which the reformed gas, which flows in the purifying passage 400, and the oxidizing air (or a so-calledoxygen component) , which flows in the oxidizing-air passage 62c, flow together. Then, the reformed gas and oxidizing air, which are joined together, flow into the CO-oxidizing remover 37 through the inlet 37i, which is disposed on the bottom side of the CO-oxidizing remover 37. The CO-oxidizing remover 37 carries out the oxidation reaction (i.e., CO + 1/2O ₂ > CO ₂ ) using oxygen as set forth in chemical equation (3) above. As a result, the CO-oxidizing remover 37 oxidizes carbon monoxide, which is contained in the reformed gas, to further reduce the carbon monoxide. Note that the oxidation reaction accompanies heat generation.

[θO5l] The present reforming system supplies the thus purified reformed gas as anode gas to the inlet Hi of the fuel cell l's fuel electrode 11 through the outlet 37p of the CO-oxidizing remover 37 via the anode-gas passage 100 and valve 25e. At the same time, the present reforming system actuates the pump27k and valve 25k to supply air functioning as cathode gas to the inlet 12i of the fuel cell l's oxidizing-agent electrode 12 through the cathode-gas passage 200. Accordingly, the fuel cell 1 produces electric-power generation reaction, thereby generating electric energy or power. The off gas or gas being exhausted out of the fuel cell 1, that is, the anode gas that has undergone the electric-power generation reaction, might contain hydrogen, which has not been used for the electric-power generation reaction. Consequently, the present reforming system supplies the off gas to the combuster 30 of the

reforming apparatus 2's reformer 34 through the off-gas passage 110 to burn it at the combuster 30, thereby turning it into another heat source for the combuster 30.

[θO52] Immediately after the present reforming system turns on the reforming apparatus 2, the reformed gas might not necessarily have sufficiently stable composition. Accordingly, upon turning on the reforming apparatus 2, the present reforming system closes the valve 25e and valve 25f . Under the circumstances, the reformed gas, which is discharged out of the CO-oxidizing remover 37' s outlet 37p, passes the valve 25h (i . e. ,. claimed outlet-side valve), and is then fed to the combuster 30 of the reforming apparatus 2' s reformer 34 through the bypass passage 150 and off-gas passage 110, thereby turning it into heat source for the combuster 30. When time has elapsed since the present reforming system turns on the reforming apparatus 2, the reformed gas has stabilized composition. In this instance, the present reforming system closes the valve 25h and opens up the valve 25e and valve 25f. Consequently, the reformed gas, which is discharged out of the CO-oxidizing remover 37' s outlet 37p, is supplied as anode gas to the inlet Hi of the fuel cell l's fuel electrode 11 through the anode-gas passage 100 via the valve 25e, and is thereby used for electric-power generation reaction.

[0053] As illustrated in Fig.1, thepresent reforming systemfurther comprises a CO-shifter temperature detector 55 for detecting temperature TH on an upstream side of the CO shifter 5 (or on a side of the CO shifter 5' s inlet 5i) . Moreover, the present reforming system further comprises a CO-shifter temperature detector 39 for detecting temperature T31 at around a turnaround 5m of the CO shifter 5. In addition, the present reforming system further comprises a

CO-shifter temperature detector 38 for detecting temperature T12 on the CO-oxidizing remover 37' s upstream side. Moreover, the present reforming system further comprises a reformer temperature detector 31t for detecting temperature Tl on the reformer 34' s outlet side. In addition, the present reforming system further comprises a temperature detector 65 for detecting temperature T2 at the first confluence Ml at which the water vapor and the reforming raw material flow together. Moreover, as shown in Fig. 1, the present reforming system further comprises a controller 500. Note that the controller 500 comprises a not-shownmicrocomputer, an input processing circuit, an output processing circuit, andamemory 502. Moreover, thepresent reforming system according to Example No. 1 inputs signals, which a turn-on switch 504 and a turn-off switch 505 output, into the controller 500.

[0054] Themajor constituent elements of thepresent reforming system will be hereinafter described in detail. The operating reforming apparatus 2 generates reformed gas whose maj or component is hydrogen, that is, which contains hydrogen in an amount of 40% by mol or more. When turning off the electric-power generation operation of fuel-cell system, the present reforming system executes reforming-operation turning-off procedure for turning off the reforming apparatus 2's reforming operation. On this occasion, the pump 27m is turned off, thereby turning off supplying reforming water to the reforming apparatus 2' s evaporator 36. Moreover, since the pump 27a is turned off so that combusting fuel (e.g., processed municipal utility 13A gas that is highly calorific) comes not to be supplied to the reforming apparatus 2's combuster 30, the combustion at the combuster 30 is turned off. Accordingly, because of heat dissipation, the reforming

apparatus 2 cools gradually as time elapses. However, immediately after turning off the reforming apparatus 2's reforming operation, since the reforming apparatus 2 still keeps exhibiting high temperature because of remaining heat, liquid-phased water, which remains in the reforming apparatus 2, that is, in the evaporator 36 mainly, is heated by the remaining heat to turn into water vapor. Consequently, thepressure Pl insidethe reformingapparatus 2 becomes higher pressure gradually.

[0055] At this moment, the present reforming system actuates the controller 500 to execute reforming-operation turning-off procedure in which the controller 500 carries out the following procedures

(a) , (b) and (c) .

(a) The controller 500 shuts off the valve 25a, valve 25b, valve 25d and valve 25m that make the claimed inlet-side valve;

(b) After first predetermined time (from 0.5 to 20 seconds, preferably from 0.5 to 10 seconds, for instance) has passed since the controller 500 shuts off the valve 25a, valve 25b, valve 25d and valve 25m, the controller 500 carries out closing procedure in which it closes the valve 25e, making a claimed outlet-side valve being connected to the inlet Hi of the fuel cell l's fuel electrode 11, the valve 25h, making another claimed outlet-side valve being connected to the outside, and the valve 25f, making still another outlet-side valve being connected to the outlet Hp of the fuel cell l's fuel electrode 11. In short, the controller 100 closes the outlet-side valves retardingly in terms of time after it closes the inlet-side valves; and

(c) Then, the liquid-phased water, which remains in the reforming apparatus 2, is heated by the reforming apparatus 2's

remaining heat. Accordingly, the pressure Pl inside the reforming apparatus 2 increases to a predetermined pressure, for instance, to 5 kPa by gauge pressure. Thereupon, the controller 500 carries out opening/closing procedure. Specifically, the controller 500 opens the valve 25h (i.e., one of the claimed outlet-side valves) by sixth predetermined time δt while keeping the valve 25a, valve 25b, valve 25d and valve 25m that make the claimed inlet-side valve being closed. Consequently, the controller 500 lets out the higher pressure inside the reforming apparatus 2 through the temporarily opened valve 25h. Thereafter, the controller 500 closes the temporarily opened valve 25h (i.e., one of the claimed outlet-side valves being connected to the outside through the combusted-exhaust-gas passage 250) again. Note herein that it is allowable to carry out this opening/closing procedure (c) once, or to carry it out a plurality of times . In other words, it is preferable to open the valve 25h (i.e., one of the claimed outlet-side valves) every time the remaining liquid-phased water turns into water vapor to increase the pressure Pl inside the reforming apparatus 2 to the predetermined pressure. As described above, every time the pressure Pl inside reforming apparatus 2 increases to the predetermined pressure, since the present reforming system according to Example No. 1 actuates the controller 500 to open the valve 25h (i.e., one of the claimed outlet-side valves) to let out the increasing pressure Pl from the reforming apparatus 2, it is possible to inhibit the pressure Pl inside the reforming apparatus 2 from increasing excessively. Therefore, the present reforming system makes it possible to manufacture the reforming apparatus 2 free of superfluously high pressure-proof structure.

[ 0056 ] When the controller 500 executes a series of the above-described reforming-apparatus turning-off procedures, it is possible to inhibit the entire reformed gas, which is generated inside the reforming apparatus 2, from being discharged to the outside of the reforming apparatus 2 completely. Accordingly, it is possible to actively keep the reformed gas whose major component is hydrogen remaining inside the reforming apparatus 2 in a considerable amount. Specifically, since the controller 500 carries out the closing procedure in which it closes not only the valve 25a, valve 25b, valve 25d and valve 25m that make the claimed inlet-side valve but also the valve 25e, valve 25h andvalve 25f that make the claimed outlet-side valve, it is possible to keep the reformed gas whose major component is hydrogen exhibiting reducing ability residing inside the reforming apparatus 2 as much as possible or as long as possible . Consequently, during turning off the reforming apparatus 2's reforming operation and during putting the reforming apparatus 2 on standby, it is possible to inhibit the catalysts 34e, 37e and 5e, which are loaded inside the reforming apparatus 2, from being degraded by oxidation. Therefore, the catalysts 34e, 37e and 5e exhibit improved durability.

[0057] However, when the controller 500 turns off the reforming apparatus 2's reforming operation, water vapor condenses in the reforming apparatus 2 as the reforming apparatus 2, which is heated to high temperature, cools. As a result, such a phenomenon might occur that the reforming apparatus 2' s inside turns into excessively negative-pressure state. If such is the case, as the reforming apparatus 2' s inside turns into excessively negative-pressure state, outside air. might go into the inside of the reforming apparatus 2 superfluously via the valve 25a, valve 25b, valve 25d and valve 25m,

or via the valve 25e, valve 25h and valve 25f. As a result, the catalysts 34e, 37e and 5e might be degraded by oxidation during the controller 500 puts the reforming apparatus 2 on standby, because the outside air comprises air that contains oxygen. In order to inhibit such a fear from arising, it is preferable to make the valve 25a, valve 25b, valve 25d and valve 25m, which constitute the claimed inlet-side valve, and the valve 25e, valve 25h and valve 25f, which constitute the claimed outlet-side valve, with an expensive special valve that exhibits strong closability and high pressure-resistance sealability, respectively. However, such a countermeasure is not preferable from the viewpoint of cost reduction, because the thus made outlet-side valves and inlet-side valves are highly costly. [0058] As described above, since the reforming system according to Example No. 1 of the present invention keeps the reforming gas whose major component is hydrogen remaining inside the reforming apparatus 2 actively, it can prevent the pressure inside the reforming apparatus from turning into negative pressure excessively even when the cooling of the reforming apparatus 2 develops. Therefore, the reforming system according to Example No. 1 of the present invention can inhibit outside air, which contains oxygen, from going into the inside of the reforming apparatus 2 superfluously. It is for this reason that the catalysts 34e, 37e and 5e, which are loaded inside the reforming apparatus 2, from being degraded by oxidation and thereby they exhibit improved durability. Accordingly, it is not necessarily required to make the valve 25a, valve 25b, valve 25d and valve 25m, which constitute the claimed inlet-side valve, and the valve 25e, valve 25h and valve 25f, which constitute the claimed outlet-side valve, with an expensive special valve that exhibits

strong closability and high pressure-resistance sealability, respectively, but it is possible to employ an inexpensive usual valve that exhibits ordinary closability to make them. Consequently, the reforming system according to Example No. 1 of the present invention contributes to manufacturing the reforming apparatus 2 at reduced cost.

[ 0059 ] Immediately after the controller 500 carries out the reforming-operation turning-off procedure, and if the reforming apparatus 2's reformer 34 is still kept in high-temperature state, the reforming rawmaterial andwater, which reside inside the reformer 34, might cause reforming reaction. In this instance, the gaseous volume increases inside the reformer 34. For example, when the reforming raw material contains CH ₄ , the gaseous volume inside the reformer 34 increases because the reforming reaction develops according to a chemical equation, CH ₄ + H ₂ O > 3H ₂ + CO, so that the total molar number of the starting materials is 2 mol before the reforming reaction and the total molar number of the products is 4 mol after the reforming reaction. In view of this, the reforming system actuates the controller 500 not only to keep the valve 25e and valve 25f, which constitute the claimed outlet-side valve, being closed while opening the valve 25h, which communicates with the outside and constitutes the claimed outlet-side valve, but also to close the valve 25a, valve 25b, valve 25d and valve 25m, which constitute the claimed inlet-side valve. Then, after the first predetermined time has passed, the reforming system actuates the controller 500 to close the valve 25h, which constitutes the claimed outlet-side valve. Thus, the reforming system enables the reformed gas whose major component is hydrogen to reside inside the reforming

apparatus 2 as much as possible. Accordingly, while inhibiting the catalysts 34e, 37e and 5e, which are loaded inside the reforming apparatus 2, from being degraded by oxidation, the reforming system enables the gases inside the reforming apparatus 2 to be discharged to the outside through the valve 25h, which communicates with the outside and constitutes the claimed outlet-side valve . Consequently, it is possible for the reforming system to cope with the increasing gaseous volume inside the reforming apparatus 2, or cancel the adverse effect thereof specifically. Note that the first predetermined time specified above depends on the specific types of the valve 25h, which communicates with the outside and constitutes the claimed outlet-side valve. However, the first predetermined time can preferably fall in a range of from 5 to 25 seconds, more preferably in a range of from 10 to 20 seconds. Specifically, for a time period of these preferable ranges of the first predeterminedtime, since the reforming system discharges the water vapor inside the reforming apparatus 2 through the valve 25h, which communicates with the outside and constitutes the claimed outlet-side valve, in a predetermined amount, it can inhibit the condensation of water vapor inside the reforming apparatus 2 from resulting in turning the pressure therein into negative pressure excessively, and it can keep hydrogen residing inside the reforming apparatus 2 as much as possible. However, when the first predetermined time is too short, the discharge of water vapormight be deficient so that the advantageous effect of inhibiting the pressure inside the reforming apparatus 2 from turning into negative pressure excessively might be effected less. On the other hand, when the first predetermined time is too long, hydrogen might remain less inside the reforming apparatus 2. As described above,

since the reforming system can keep the reformed gas whose major component is hydrogen remaining inside the reforming apparatus 2 as much as possible, it can inhibit the catalysts 34e, 37e and 5e, which are loaded inside the reforming apparatus 2, frombeing degraded by oxidation so that it contributes to prolonging the catalysts' longevity advantageously.

[θO6θ] Moreover, the reforming system can additionally inhibit the pressure inside the reforming apparatus 2 from turning into negative pressure excessively in the following manner. Specifically, at around the termination of the reforming-operation turning-off procedure, the controller 500 opens the valve 25a and valve 25b, which constitute the claimed inlet-side valve, temporarily while actuating the pump 27b, thereby charging gaseous reforming gas (or 13Agas, that is, higher calorific-value processed municipal utility gas) into the reforming apparatus 2. As a result, the charged gaseous reforming gas inhibits the pressure inside the reforming apparatus 2 from turning into negative pressure excessively. Therefore, it is not necessarily required that not only the valve 25a and 25b, which constitute the claimed inlet-side valve, but also the valve 25h, which constitutes the claimed outlet-side valve, be made with an expensive special valve that exhibits strong closability and high pressure-resistance sealability, respectively, but it is possible that they can be made with an inexpensive ordinary valve whose pressure-resistant sealability is not necessarily high, respectively. To put it differently, the reforming system allows outside air to go into the inside of the reforming apparatus 2. Note herein that valve whose pressure-resistant sealability is not high so much contributes to saving electric energy because it requires

such less spring force for closing that less electromagnetic force is needed to reopen the valve against the less spring force. In addition, oxygen, which is contained in the outside air, is consumed, because it reacts with the hydrogen component of the reformed gas, which remains in the reforming apparatus 2' s reformer 34. Therefore, even if the outside air should have gone into the reforming apparatus 2, it is possible to inhibit oxygen, which is contained in air, from adversely affecting the catalysts 34e, 37e and 5e that are loaded inside the reforming apparatus 2.

[006l] Moreover, though the present reforming system allows outside air to go into the reforming apparatus 2's reformer 34, note that nitrogen gas accounts for the major proportion of outside air. In addition, the present reforming system keeps the reformed gas whose major component is hydrogen exhibiting reducing ability residing inside the reforming apparatus 2 actively. Accordingly, hydrogen, which remains in the reforming apparatus 2 actively, reacts with oxygen, which is contained in the outside air going actively into the inside of the reforming apparatus 2, to consume the oxygen. Consequently, the hydrogen reduces the oxygen, which goes into the reforming apparatus 2, by consuming the oxygen. Therefore, the present reforming system is advantageous for inhibiting the catalysts 34e, 37e and 5e, which are loaded inside the reforming apparatus 2, from being degraded by oxidation.

[0062] Inaddition, as described above, the present reforming system operates the controller 500 to charge gaseous reforming raw material to the reforming apparatus 2's reformer 34 upon turning off the reforming apparatus 2's reforming operation. Accordingly, the pressure inside the reformer 34 can be inhibited from turning into

negative pressure excessively. Consequently, even if outside air should have gone into the inside of the reforming apparatus 2, it is possible to control the amount of gone-into outside air at a prescribed amount of 40 kPa by gauge pressure, for instance. As far as outside air goes into the reforming apparatus 2 in such a controlled amount, it is possible to inhibit oxygen, which is contained in the gone-into outside air, from consuming all of hydrogen, which is contained in the reformed gas residing inside the reforming apparatus 2, completely. Therefore, the present reforming system can keep hydrogen remaining inside the reforming apparatus 2 in a satisfactory amount. Thus, the present reforming system can advantageously inhibit the catalysts 34e, 37e and 5e, which are loaded inside the reforming apparatus 2, from being degraded by oxidation. [0063] The present reforming system operates the controller 500 so that it actuates thepump 27c to flow air into the reforming apparatus 2' s combuster 30 as cooling gas through the air passage 73; and then flows combusted exhaust gas out of the combuster 30 through the combusted-exhaust-gas passage 250 by way of the combustion passage 32. As a result, the air cools down the reforming apparatus 2 actively. That is, the present reforming system can inhibit the reforming apparatus 2 from cooling gradually after turning off the reforming apparatus 2's reforming operation. Since the present reforming system thus cools down the reforming apparatus 2 facultatively, it can prevent the reforming apparatus 2's constituent materials from degrading. For example, when the reforming apparatus 2 is made using alloy steel, such as stainless steel, it is possible to inhibit the alloy steel from being cooled gradually at high temperature, at around 475 ⁰ C, for instance. Therefore, the present reforming

system is advantageous for preventing the reforming apparatus 2 from undergoing high-temperature degradation, such as the 475- °C embrittlement .

[0064] Moreover, when the reforming apparatus 2 is made using stainless steel as one of the reforming apparatus 2's constituent materials, the present reforming system according to Example No. 1 is advantageous for inhibiting the embrittlement of stainless steel from occurring. Note that the embrittlement arises when holding stainless steel at a temperature of from 400 to 900 ⁰ C for a long period of time, for instance. In addition, when the reforming apparatus 2 is made from stainless steel, the present reforming system is advantageous for preventing the sensitization of stainless steel from arising. Note that the sensitization is likely to arise when holding stainless steel at a temperature of from 500 to 850 ⁰ C for a predetermined period of time, for instance.

[0065] In addition, it is preferable that, under the circumstances that hydrogen resides inside the reforming apparatus 2, the present reforming system can operate the controller 500 so that it increases the temperature of the reforming apparatus 2's CO-oxidizing remover 37 to 200 °C or more, more preferably from 200 to 400 °C, temporarily before completing the reforming-operation turning-off procedure. In this way, it is possible to facultatively recover the catalyst 37e that is loaded inside the CO-oxidizing remover 37 by subjecting the catalyst 37e to reducing treatment. As a specific method for the preferable modification, it is preferable to exemplify the following method, which comprises the steps of: having the fuel cell 1 generate electric power at minimum output (for example, at 300 W when the fuel cell l's rated output is 1 kW) for a time period

of from 1 to 10 minutes, for instance, immediately before turning off electric power generation, thereby reducing residual water vapor inside the reforming apparatus 2' s evaporator 36; turning off electric power generation after confirming the CO-oxidizing remover 37' s temperature T2 is 105 °C or more; and commencing to execute the reforming-operation turning-off procedure. As an alternative specific method for the preferable modification, it is allowable to dispose heat-insulating means between the evaporator 36 and the CO-oxidizing remover 37.

[0066] (Example No. 2)

[0067] A reforming system according to Example No.2 of the present invention will be hereinafter described while likewise making use of Figs. 1 and 2, because it comprises the same constituent elements and operates and effects the same advantages as those of the present reforming system according to Example No. 1 fundamentally. Fig. 3 is a timing chart for illustrating how the controller 500 of the present reforming system according to Example No. 2 operates. In Fig. 3, time ta designates a time at which the fuel cell 1 completes the electric power generation and the controller 500 starts the reforming-operation turning-off procedure; time tb designates a time at which the controller 500 completes the reforming-operation turning-off procedure and then starts the reforming apparatus 2 putting on standby; and time tc designates a time at which the controller 500 finishes putting the reforming apparatus 2 on standby and then starts running the reforming apparatus 2. Moreover, in Fig. 3, a characteristic curve Wl specifies the pressure Pl inside the reforming apparatus 2; and a characteristic curve W2 specifies the residual amount of hydrogen, which resides inside the reforming

apparatus 2. Note that the residual hydrogen amount was derived value that was calculated from the actuallymeasured value of hydrogen concentration. In addition, in Fig. 3, a characteristic curve W3 specifies the ratio of the pressure of H ₂ (i.e., P(H ₂ )) inside the reforming apparatus 2 to the pressure of H ₂ O (i.e., P(H ₂ O)) inside the reforming apparatus 2 (i.e., P (H ₂ ) / P (H ₂ O) ). Note that the ratio P (H ₂ ) / P (H ₂ O) was derived value that was calculated from the actually measured value of hydrogen and water-vapor pressures. Moreover, in Fig.3, a characteristic curve WE specifies an oxidizing/reducing characteristic (or oxidizing/reducing boundary curve) , which the catalyst 37e exhibits (that is, a catalyst, whose importance is higher of the catalysts 34e and 37e that are loaded inside the reforming apparatus 2's reformer 34, exhibits). In the upper region above the characteristic curve WE, the catalyst 37e is inhibited from being oxidized. In the lower region below the characteristic curve WE, the catalyst 37e is oxidized.

[0068] The present reforming system according to Example No. 2 likewise generates the reformed gas, whosemajor component is hydrogen, by running the reforming apparatus 2. Thereafter, upon turning off the fuel cell 1' electric-power generation operation, the present reforming system according to Example No. 2 actuates the controller 500 to terminate the reforming apparatus 2's reforming operation at the time ta.

[0069] When turning off the reforming apparatus 2's reforming operation, the controller 500 carries out the reforming-operation turning-off procedure. In the reforming-operation turning-off procedure, the controller 500 first closes the opened valves 25a, 25b, 25d and 25m, which constitute the claimed inlet-side valve,

and additionally the opened valves 25e and 25f, which constitute the claimed outlet-side valve. Note herein that, as illustrated in Fig. 3, the controller 500 closes the valve 25h, which constitute the claimed outlet-side valve, at timing t2 that is delayed by first predetermined time δtx fromtiming tl . Specifically, the controller 500 opens the valve 25h in retard of the timing tl for a time period of the first predetermined time δtx (from 5 to 20 seconds, for instance) .

[ 0070 ] When the controller 500 executes the above-described reforming-operation turning-off operation, the present reforming system according to Example No.2 discharges the reformed gas, which is generated inside the reforming apparatus 2 and whose major component is hydrogen, to the outside while keeping the resulting reformed gas remaining inside the reforming apparatus 2 as much as possible. To put it differently, the present reforming system according to Example No.2 discharges the reformed gas, which contains hydrogen as the major component, extremely less. Accordingly, the present reforming system according to Example No. 2 can keep the reformed gas, whose major component is hydrogen exhibiting reducing ability, residing inside the reforming apparatus 2 as long as possible . Consequently, the present reforming system according to Example No. 2 can inhibit the catalysts 34e, 37e and 5e from being degraded by oxidation.

[007l] Note herein that it is possible to think of such a method that the controller 500 closes the valve 25h in retard of the timing tl for a time period of the first predetermined time δtx. If such is the case, however, it is not possible to discharge the gases, which are present inside the reforming apparatus 2 and contain

hydrogen and water vapor, early, because the valve 25h is closed beyond the timing tl. Accordingly, when the controller 500 first opens the valve 25h in order to release the pressure inside the reforming apparatus 2, the gases are likely to return to the reforming apparatus 2's combuster 30 in a large amount via the valve 25h and off-gas passage 110. On this occasion, the combuster 30 might make reigniting sounds. In view of the possible drawback, the present reforming system according to Example No. 2 employs the above-described method in which the controller 500 opens the valve 25h retardingly by the first predetermined time δtx from the timing tl. Consequently, it is possible to discharge the gases, which are present inside the reforming apparatus 2 and contain hydrogen and water vapor, early. Note that, in the present reforming system according to Example No.2, although the gases return to the reforming apparatus 2's combuster 30 via the valve 25h and off-gas passage 110 when the controller 500 opens the valve 25h by the first predetermined time δtx, the combuster 30 can continue burning the gases without making any reigniting sounds because it still exhibits high temperature.

[0072] Then, the present reforming system according to Example No. 2 actuates the controller 500 to keep the valve 25a, 25b, 25d and 25m, which constitute the claimed inlet-side valve of the reforming apparatus 2, closing, that is, to maintain the closed state of the reforming apparatus 2. Under the circumstances, the pressure Pl inside the reforming apparatus 2 increases as the curved section WIb of the characteristic curve Wl specifies, because the water vaporization of liquid-phased water, which resides inside the high-temperature reforming apparatus 2, develops. At timing t4 at

which the pressure Pl increases to predetermined pressure P2, for instance, to 5 kPa by gauge pressure, the controller 500 opens the valve 25h instantaneously for a short period of time δt (or sixth predetermined time) . Thus, the controller 500 releases high pressure inside the reforming apparatus 2 (or carries out a first pressure releasing process) , thereby inhibiting the pressure inside the reforming apparatus 2 from increasing excessively. Note that, even thereafter, the pressure Pl inside the reforming apparatus 2 increases as the curved section WIc of the characteristic curve Wl specifies, because the high-temperature reforming apparatus 2's remaining heat further turns the liquid-phasedwater into water vapor . Moreover, in addition to the timing t4, at timings t5 and tβ at which the pressure Pl increases to the predetermined pressure P2, the controller 500 accordingly reopens the valve 25h instantaneously for a short period of time δt to release high pressure inside the reforming apparatus 2 (or carries out a second pressure releasing process) , thereby inhibiting the pressure inside the reforming apparatus 2 from increasing excessively. Consequently, the present reforming system according to Example No. 2 makes it unnecessary to enhance the pressure resistance of the reforming apparatus 2 superfluously.

[0073] Moreover, as the characteristic curve W4 designates, the present reforming system according to Example No. 2 actuates the controller 500 to keep running the pump 27c continuously from the initial stage of the reforming-operation turning-off procedure. Accordingly, the pump 27c keeps supplying air to the reforming apparatus 2's combuster 30 by way of the combusting-air passage 73, thereby executing a forcible coolingprocess for cooling the reforming

apparatus 2 forcibly. Note herein that, while the air cools the reforming apparatus 2, the air, which the pump 27c supplies to the combuster 30, is flowed through the combuster 30' s combustion passage 32 and combustion passage 33, and is then discharged to the outside through the combusted-exhaust-gas passage 250. On this occasion, the reforming apparatus 2' s CO-oxidizing remover 37 tends to exhibit warming-up temperature, because the air is warmed while flowing and because the warmed air then passes around the reforming apparatus 2. Therefore, the present reforming system according to Example No. 2 can contribute to recovering the catalyst 37e that is loaded inside the CO-oxidizing remover 37.

[0074] In addition, as time elapses, the temperature Tl of the reforming apparatus 2 ' s reformer 34 decreases . At timing 18 at which the temperature Tl of the reformer 34 decrease to lower-temperature-side predetermined temperature, that is, to a temperature of from 100 to 200 °C, for instance, to 150 °C, especially, the present reforming system according to Example No. 2 turns the timing t8 into a trigger signal for operating the controller 500 to turn off the pump 27c, thereby turning off supplying the air to the reforming apparatus 2' s combuster 30 by way of the combusting-air passage 73. Thus, the controller 500 turns off the forcible cooling process for cooling the reforming apparatus 2 forcibly. Moreover, as illustrated in Fig. 3, the controller 500 opens the valve 25a and valve 25b, which constitute the claimed inlet-side valve, while operating the pump 27b, thereby supplying the gaseous reforming raw material into the inside of the reforming apparatus 2 once, or a plurality of times depending on specific cases. Thus, the pressure Pl inside the reforming apparatus 2, which a pressure sensor detects,

increases to a predetermined pressure P3, to 20 kPa approximately, for instance, as the curved section WIr of the characteristic curve Wl specifies . Thereafter, the pressure Pl, which the pressure sensor detects, decreases gradually and eventually to an appropriate negative pressure Pe, to -15 kPa approximately, for instance, as the curved section WIe of the characteristic curve Wl specifies. Then, the controller 500 puts the reforming apparatus 2 on standby. Therefore, the present reforming system according to Example No. 2 can inhibit the pressure inside the reforming apparatus 2 from turning into negative pressure excessively.

[0075] As described above, the present reforming system according to Example No. 2 actuates the controller 500 to supply the gaseous reforming raw material into the inside of the reforming apparatus 2 when the temperature Tl of the reforming apparatus 2's reformer 34 decreases to a predetermined temperature, to a temperature of from 100 to 200 °C, for instance, to 150 ⁰ C, especially. Note that, at the predetermined temperature, the caulking of the gaseous reforming raw material does not occur at all in the reformer 34. Accordingly, the present reforming system according to Example No. 2 inhibits the gaseous reforming raw material from caulking in the reformer 34. Consequently, it enables the reformer 34 to exhibit upgraded durability.

[0076] Moreover, at the time tc, the present reforming system according to Example No. 2 operates the controller 500 to finish putting the reforming apparatus 2 on standby, and then to commence the start-up of the reforming apparatus 2. Upon starting up the reforming apparatus 2, the controller 500 activates the pump 27b, and additionally opens the valves 25a and 25b, which constitute the

claimed inlet-side valve, by a predetermined period of time δtm, for from 0.5 to 15 seconds, for instance, after the time tc. Thus, the controller 500 operates to supply the gaseous reforming raw material into the inside of the reforming apparatus 2's reformer 34, thereby pressurizing the inside of the reforming apparatus 2. When the inside of the reforming apparatus 2 is thus pressurized, the controller 500 judges that no gas leakage occurs in the piping of the present reforming system according to Example No. 2 so that the piping is under normal condition if no decrement is appreciable in the pressure Pl inside the reforming apparatus 2 for a predetermined time TK, for 300 seconds, for instance. In addition, when the controller 500 judges that the piping is under normal condition upon starting the reforming apparatus 2' s reforming operation, note that, in order to cut down the controller 500' s standby electric power, it is allowable to make the controller 500 free of the operation for monitoring the reforming apparatus 2 by stopping the electric-power supply to the controller 500 while it turns off the reforming apparatus 2's reforming operation and puts the reforming apparatus 2 on standby for the next round of operation.

[ 0077 ] Table 1 below sets forth specific samples of the concentrations of hydrogen contained in gases, the number of moles of hydrogen contained in gases, and the P (H ₂ ) / P (H ₂ O) pressure ratios when a test of turning off the reforming apparatus 2's reforming operation was conducted using the present reforming system according to Example No.2. Note that the calculated values shown below agreed substantially with the actually measured values fundamentally.

TABLE 1

[0078] (Example No. 3)

[0079] Fig.4 is directed to a reforming system according to Example No. 3 of the present invention. The present reforming system according to Example No. 3 comprises the same constituent elements, and operates and effects the same advantages as those of the present reforming system according to Example No. 2 fundamentally. The present reforming system according to Example No. 3 will be hereinafter described while making use of Figs. 1 and 2 similarly to the present reforming systemaccording to Example No.2. Moreover, the present reforming system according to Example No. 3 will be hereinafter described while focusing on the constituent elements

that differ from those of the present reforming system according to Example No. 2. As described above, the present reforming system according to Example No. 2 operates the controller 500 to close the valve 25h, which constitutes the claimed outlet-side valve, at the timing t2 that retards by the predetermined time δtx from the timing tl as shown in Fig. 3. However, regarding the retardation, note that the present reforming system according to Example No. 3 makes the retardation by the predetermined time δtx obsolete. Therefore, as can be understood from Fig. 4, the present reforming system according to Example No. 3 operates the controller 500 to close the valves 25a, 25b, 25d and 25m, which constitute the claimed inlet-side valve, starting at the timing tl (or time ta) , and additionally operates the controller 500 to close the valves 25h, 25e and 25f, which constitute the claimed outlet-side valve, starting thereat.

[0080] (Example No. 4)

[θO8l] A reforming system according to Example No. 4 of the present invention comprises the same constituent elements, and operates and effects the same advantages as those of the present reforming systems according to Example Nos. 1 and 2 fundamentally. Accordingly, the preset reforming system according to Example No .4 will be hereinafter described while referring back to Figs .1 and 2 whenever necessarily. The present reforming system according to Example No. 4 likewise operates the controller 500 to turn off the reforming apparatus 2's reforming operation upon terminating the fuel-cell system' s operation. Specifically, the controller 500 turns off the pump 27m, thereby turning off the supply of reforming water to the reforming apparatus 2's evaporator 36. Since the controller 500 also turns off the pump 27a (or so-called means for transferring combusting

fuel) and the pump 27c (or so-calledmeans for transferring combusting air) , and thereby the pump 27a andpump 27c do not supply the combusting fuel and combusting air to the reforming apparatus 2's combuster 30. Accordingly, the controller 500 turns off the combuster 30' s combusting operation, and thereby the reforming apparatus 2 is cooled gradually as time elapses. However, the reforming apparatus 2 exhibits high temperature immediately after the controller 500 turns off the reforming operation, because it is still subjected to remaining heat . Consequently, water, which resides in the reforming apparatus 2's reformer 34, turns into water vapor, and thereby the pressure Pl inside the reforming apparatus 2 increases to higher pressure gradually.

[0082] At this moment, the present reforming system according to Example No. 4 actuates the controller 500 to execute reforming-operation turning-off operation, in which the controller 500 carries out the following procedures (a) , (b) and (c) , similarly to the above-describedpresent reforming systems according to Example Nos. 1 and 2.

(a) The controller 500 shuts off the valve 25a, valve 25b, valve 25d and valve 25m that make the claimed inlet-side valve. Note that, on this occasion, the controller 500 opens the valve 25e, valve 25h and valve 25f that make the claimed outlet-side valve;

(b) After first predetermined time (from 0.5 to 10 seconds, preferably from 0.5 to 20 seconds, for instance) has passed since the controller 500 shuts off the valve 25a, valve 25b, valve 25d and valve 25m, the controller 500 carries out closing procedure in which it closes the valve 25e, valve 25h and valve 25f; and

(c) When the pressure Pl inside the reforming apparatus 2

reaches a predetermined pressure, the controller 500 carries out opening/closing procedure in which it opens the valve 25h, which communicates with the outside and which makes the claimed outlet-side valve, for sixth predetermined time while keeping the valve 25a, valve 25b, valve 25d and valve 25m being closed (or keeping the reforming apparatus 2 being closed) , thereby letting out the higher pressure inside the reforming apparatus 2; and thereafter the controller 500 recloses the temporarily opened valve 25h.

[0083] In the present reforming system according to Example No. 4, it is likewise allowable to carry out the above-described opening/closing procedure (c) once, or to carry it out a plurality of times. In other words, it is preferable to open the valve 25h temporarily and then close it every time the pressure Pl inside the reforming apparatus 2 increases to predetermined pressure. Therefore, the present reforming system according to Example No. 4 enables the reforming apparatus 2 to be providedwith least available pressure resistance.

[0084] Moreover, the present reforming system according to Example No. 4 actuates the controller 500 to keep the pump 27c running continuously from the initial stage of the reforming-operation turning-off procedure. Accordingly, the pump 27c keeps supplying air to the reforming apparatus 2's combuster 30 through the combusting-air passage 73, thereby carrying out a forcible cooling process for cooling the reforming apparatus 2 forcibly. Consequently, it is possible to keep the reforming apparatus 2's constituent materials from being exposed to the high temperature for a long period of time. In addition, the present reforming system according to Example No.4 turns the timing, at which the temperature

Tl of the reforming apparatus 2's reformer 34 decreases to a predetermined temperature, to a temperature of from 100 to 200 ⁰ C, especially to 150 °C, for instance, into a trigger signal for letting the controller 500 turn off the pump 27c. As a result, the controller 500 turns off supplying air to the combuster 30 through the combusting-air passage 73, thereby turning off the forcible cooling process for cooling the reforming apparatus 2 forcibly.

[0085] As the controller 500 turns off the reforming apparatus 2's reforming operation, the reforming apparatus 2's reformer 34 exhibits the decreasing temperature Tl. When the temperature Tl of the reformer 34 decreases to the predetermined temperature, to a temperature of from 100 to 200 ⁰ C, especially to 150 ⁰ C, for instance, the controller 500 not only opens the valves 25a and 25b, which constitute the claimed inlet-side valve, but also activates the pump 27b, thereby supplying the gaseous reforming raw material into the inside of the reforming apparatus 2 once or a plurality of times for predetermined time tr. At this moment, since the reformer 34 still exhibits such a high temperature that is a reforming-reaction executable temperature or more, the gaseous reforming raw material undergoes reforming reaction so that the reformer 34 produces hydrogen gas actively. Note herein that, since the resulting hydrogen gas exhibits reducing ability, it is beneficial for inhibiting the catalysts 34e, 37e and 5e, which are loaded inside the reforming apparatus 2, from being degraded by oxidation when the reforming apparatus 2 is turned off or is put on standby. Thus, the reformed gas, which contains hydrogen exhibiting reducing ability as the major component, resides in the reforming apparatus 2. Moreover, the gaseous reforming rawmaterial, which has not undergone the reforming

reaction, also remains in the reforming apparatus 2 as it is. Accordingly, even when the reforming apparatus 2 cools down, it is possible for the present reforming system according to Example No. 4 to inhibit the pressure inside the reforming apparatus 2 from turning into negative pressure excessively. Consequently, it is possible for the present reforming system according to Example No .4 to prevent outside air from going into the inside of the reforming apparatus 2 superfluously. Therefore, it is possible for the present reforming system according to Example No. 4 to keep the catalysts 34e, 37e and 54, which are loaded inside the reforming apparatus 2, from being degraded by oxidation, and thereby the catalysts 34e, 37e and 54 can exhibit upgraded durability.

[0086] As described above, even when the cooling of the reforming apparatus 2 develops, the present reforming system according to Example No.4 can inhibit the pressure inside the reforming apparatus 2 from turning into negative pressure excessively. Therefore, it is not necessarily required to employ a specific expensive valve, which exhibits high pressure-resistant sealability, for making the valves 25a, 25b, 25dand25m, which constitute the claimed inlet-side valve, and the valves 25e, 25h and 25f, which constitute the claimed outlet-side valve, but it is feasible to employ an inexpensive ordinary valve for making them. Thus, the present reforming system according to Example No. 4 can contribute to reducing the cost of manufacturing reforming system. Moreover, even if air should have entered the reforming apparatus 2's reformer 34 in the present reforming system according to Example No.4, inactive nitrogen makes the major proportion of air. On the other hand, oxygen, which is contained in air, has been consumed considerably because it reacts

with the hydrogen of the reformed gas, which remains in the reformer 34. Hence, the present reforming system according to Example No. 4 can prevent oxygen, which is contained in air, from adversely affecting the catalysts 34e, 37e and 54 that are loaded inside the reforming apparatus 2.

[0087] (Example No. 5)

[0088] Since a reforming system according to Example No. 5 of the present invention comprises the same constituent elements, and operates and effects the same advantages as those of the present reforming systems according to Example Nos. 1 and 2 fundamentally, it will be hereinafter described while making use of Figs. 1 and 2 whenever necessarily. It likewise comprises the CO-oxidizing remover 37, the claimed CO reducer . Specifically, the catalyst 37e, which is loaded inside the CO-oxidizing remover 37, comprises a support being made from ceramic, and a noble-metal catalyst being loaded on the support. The support can be made from alumina, for instance. The noble-metal catalyst can be a ruthenium catalyst, a platinum catalyst, or a platinum-ruthenium catalyst, for instance. Since oxygen is supplied to the CO-oxidizing remover 37 , the oxidation degradation of the catalyst 37e is likely to develop. Accordingly, it has been required particularly to inhibit the catalyst 37e from being degraded by oxidation and eventually to enable the catalyst 37e to exhibit improved durability. In the present reforming system according to Example No.5 as well, hydrogen resides in the reforming apparatus 2 that comprises the CO-oxidizing remover 37 when the controller 500 carries out the reforming-operation turning-off procedure for turning off the reforming apparatus 2's reforming operation. Note herein that, in an atmosphere that contains hydrogen

(or in a hydrogen-rich atmosphere), the catalyst 37e ^f s activation temperature range (or recovery temperature range) lies in 200 °C or more in general or in 220 °C or more especially, and usually falls in a range of from 200 to 450 °C.

[0089] Moreover, note that, upon turning off the fuel-cell system, the present reforming apparatus according to Example No. 5 actuates the controller 500 to executes the reforming-operation turning-off procedure for turning off the reforming apparatus 2's reforming operation. Specifically, after initiating turning off all the supplies of the reforming water, gaseous reforming raw material and oxidizing air, the controller 500 keeps the reforming apparatus 2's combuster 30 running for secondpredetermined time only. Asa result, the combuster 30 continues the fuel combusting operation for a period of the second predetermined time. On the other hand, upon completing turning off all of the supplies of the reforming water, gaseous reforming raw material and oxidizing air, the controller 500 turns off the supply of the reformed gas to the fuel cell 1.

[θO9θ] The operations of the controller 500 upon turning off the fuel-cell system will be hereinafter described in detail. Specifically, the controller 500 performs the following control in order to activate and/or recover the catalyst 37e, which is loaded inside the reforming apparatus 2's CO-oxidizing remover 37, facilitatively. That is, before carrying out the closing procedure for closing the valve 25a, valve 25b, valve 25d and valve 25m, which constitute the claimed inlet-side valve, and the valve 25e, valve 25h and valve 25f, which constitute the claimed outlet-side valve, the controller 500 actuates the reforming apparatus 2's combuster 30 (i.e., the claimed heater) to go on the combustion reaction for

the second predetermined time (i.e., for a period of from 2 to 60 minutes, preferably for a period of from 5 to 30 minutes, for instance, but not limited to these) , thereby keep heating the reforming apparatus 2's reformer 34.

[009l] To put it differently, although the supply of the reforming water, the supply of the gaseous reforming raw material and the supply of the oxidizing air to the reforming apparatus 2 are turned off so that the reforming apparatus 2's reforming operation is turned off in order to turn off the generation of the reformed gas, the combusting fuel and combusting air are supplied to the reforming apparatus 2's combuster 30 so that the combuster 30 combusts the combusting fuel to heat the reforming apparatus 2's reformer 34, for instance. Under the circumstances, since the combuster 30 carries out the combustion reaction for the second predetermined time as described above, the temperature of the reforming apparatus 2's evaporator 36 is kept high as much as possible. Accordingly, the residual water flows through the evaporator 36 in a decreased flow volume or the flow disappears virtually so that the evaporator

36 exhibits increasing temperature. Moreover, the CO-oxidizing remover 37, which neighbors on the evaporator 36, exhibits increasing temperature eventually. Consequently, the temperature of the CO-oxidizing remover 37 is kept high as much as possible . As a result, although the controller 500 is performing the above-described reforming-operation turning-offprocedure, the CO-oxidizing remover

37 keeps exhibiting a recovery temperature, at which the catalyst 37e being loaded inside the CO-oxidizing remover 37 is recoverable by means of reduction in such a state that hydrogen resides in the CO-oxidizing remover 37, for a time period of from 3 to 30 minutes,

for instance. Accordingly, the present reforming system according to Example No. 5 subjects the catalyst 37e, which is built-in inside the CO-oxidizing remover 37, to reduction treatment by means of hydrogen. Consequently, the present reforming system according to Example No. 5 can inhibit the catalyst 37e from being degraded by oxidation so that the catalyst 37e' s durability is enhanced and its longevity is made longer. In other words, every time the controller 500 turns off the reforming apparatus 2's reforming operation, the catalyst 37e, which is loaded inside the CO-oxidizing remover 37, is recoverable.

[0092] (Example No. 6)

[0093] A reforming system according to Example No. 6 of the present invention will be hereinafter described while similarly making reference to Figs. 1 and 2 whenever necessary, because it comprises the same constituent elements, and operates and effects the same advantages as those of the present reforming systems according to Example Nos.1 and 2 fundamentally. When the present reforming system according to Example No.6 turns off the fuel-cell system, it actuates the controller 500 to likewise executes the reforming-operation turning-off procedure for turning off the reforming apparatus 2's reforming operation. While carrying out the reforming-operation turning-off procedure, the controller 500 performs an extra control for facilitating the activation and recovery of the catalyst 37e, which is loaded inside the reforming apparatus 2's CO-oxidizing remover 37 and which is likely to be degraded, as described below. Specifically, the controller 500 turns off the supply of the reformed gas to the fuel cell 1. Note that this operation might be referred to as "halting the fuel cell 1" wherever appropriate . In this instance,

however, the controller 500 operates to supply the oxidizing-agent gas, cathode air, to the fuel cell 1 for a while. Thereafter, under such a condition that the supply of the oxidizing air is turned off, the controller 500 operates to keep the reforming apparatus 2 running for third predetermined time while decreasing the supplied flow volumes of the reforming water and gaseous reforming raw material. Subsequently, the controller 500 turns off the reforming apparatus 2' s operation completely, that is, turns off both of the supplies of the reforming water and gaseous reforming raw material to the reforming apparatus 2's combuster 30.

[0094] In short, the controller 500 keeps the reforming apparatus 2 carrying out the reforming operation for the third predetermined time (i.e., for a time period of from 2 to 60 minutes, preferably for a time period of from 5 to 30 minutes, for instance, but not limited to these) , though it turns off the fuel cell 1' s electric-power generation operation. Thus, the temperature of the reforming apparatus 2's evaporator 36 is maintained at temperature as high as possible. Accordingly, the water remains inside the evaporator 36 in a decreased amount, or disappears virtually. Eventually, the temperature decrement rate of the CO-oxidizing remover 37 slows down. Alternatively, as the temperature of the evaporator 36 increases, the CO-oxidizing remover 37 exhibits increasing temperature. Consequently, the CO-oxidizing remover 37 is kept at temperature as high as possible. Therefore, it is possible to maintain the temperature of the CO-oxidizing remover 37 at a recovery temperature, which enables the catalyst 37e being loaded inside the CO-oxidizing remover 37 to recover, for a time period of from 3 to 30 minutes, for instance, satisfactorily. On this occasion, since hydrogen

resides in the CO-oxidizing remover 37, the residing hydrogen reduces the catalyst 37e that is loaded inside the CO-oxidizing remover 37. Thus, the present reforming system according to Example No. 6 can inhibit the catalyst 37e from being degraded by oxidation, thereby upgrading the durability of the catalyst 37e.

[0095] (Example No. 7)

[0096] A reforming system according to Example No. 7 of the present invention will be hereinafter described. Since it comprises the same constituent elements, and operates and effects the same advantages as those of the present reforming systems according to Example Nos. 1 and 2 fundamentally, Figs. 1 and 2 will be similarly applied to describe it whenever necessary. In the present reforming system according to Example No. 7, upon turning off the fuel-cell system, the controller 500 likewise executes the reforming-operation turning-off procedure for turning off the reforming apparatus 2's reforming operation. In order to facultatively activate and recover the catalyst 37e, which is loaded inside the reforming apparatus 2's CO-oxidizing remover 37 and which is likely to be degraded, , the controller 500 performs the following extra control during the reforming-operation turning-off procedure. Specifically, the controller 500 reduces the output of the fuel cell 1, and additionally slows down the reforming apparatus 2' s reforming operation. In this instance, the controller 500 keeps the fuel cell 1 ' s electric-power generation operation running in low-output region for fourth predetermined time, for a time period of from 1 to 60 minutes, preferably from 5 to 30 minutes, for instance. Note herein that, when the fuel cell l's electric-power-generation output upon the fuel cell l's rated operation is expressed as 100% relatively,

the low-output region can preferably fall in a range of from 5 to 50%, more preferably from 10 to 40%, with respect to the fuel cell l's electric-power-generation output upon the fuel cell l's rated operation. For example, the low-output region can preferably be the fuel cell l's minimum-load operation range. The term, "rated," herein designates a limit of the fuel cell 1 in service, limit which the manufacture guarantees that the fuel cell 1 can demonstrate the limit when it is operated under the conditions that the manufacturer specifies, and is usually displayed on the fuel cell l's name plate, for instance.

[0097] In short, during the reforming-operation turning-off procedure, the controller 500 not only operates the fuel cell 1 to output electric power in the minimum-load operation range, for instance, but also slows down the reforming apparatus 2's reforming operation. Accordingly, the combusting fuel and combusting air are supplied to the reforming apparatus 2's combuster 30, and thereby the combuster 30 combusts the combusting fuel. Consequently, the reforming apparatus 2' s reformer 34 is heated, and the heat resulting in the reformer 34 is then transmitted to the reforming apparatus 2's evaporator 36 and CO-oxidizing remover 37. At the same time, not only the reforming water is supplied to the evaporator 36 but also the gaseous reforming raw material is supplied to the reformer 34. On this occasion, the controller 500 controls the supplies of the reforming water and gaseous reforming raw material so that the S/C (i.e. , the ratio of steam to carbon) falls at around 3 by volume in the reformer 34.

[0098] Specifically, the controller 500 opens the valve 25a and actuates the pump 27a. As a result, the combusting fuel is supplied

to the reforming apparatus 2's combuster 30 through the combusting-fuel passage 62a. Further, the controller 500 actuates the pump 27c. As a result, the combusting air is supplied to the combuster 30 through the combusting-air passage 73. Furthermore, the controller 500 opens the valves 25a and 25b and actuates the pump 27b. As a result, the gaseous reforming raw material is supplied to the reforming apparatus 2's reformer 34 through the reforming-raw-material passage 62c. Moreover, the controller 500 opens the valve 25m in the reforming-water passage 82a and actuates the pump 27m. As a result, the reforming water is supplied to the reforming apparatus 2's evaporator 37 through the reforming-water passage 82.

[0099] As described above, since the controller 500 keeps the reforming apparatus 2's combuster 30 carrying out the combustion reaction, the reforming apparatus 2's reformer 34 is heated so that the reforming apparatus 2! s evaporator 36 is inhibited fromexhibiting decreasing temperature, or so that the evaporator 36 exhibits increasing temperature. Accordingly, the evaporator 36 keeps exhibiting temperature as high as possible. Consequently, the flow volume of remaining water in the evaporator 36 decreases, or the flow disappears virtually. Therefore, the reforming apparatus 2's CO-oxidizing remover 37 exhibits increasing temperature, or is inhibited from exhibiting decreasing temperature. Hence, the controller 500 can maintain the temperature of the CO-oxidizing remover 37 at the recovery temperature of the catalyst 37e, which is loaded inside the CO-oxidizing remover 37, satisfactorily during the reforming-operation turning-off procedure. On this occasion, the catalyst 37e that is loaded inside the CO-oxidizing remover 37

is reduced by hydrogen, because hydrogen resides in the CO-oxidizing remover 37 in a considerable amount as described above. Thus, it is possible for the present reforming system according to Example No. 7 to inhibit the catalyst 37e from being degraded by oxidation so that the catalyst 37e can exhibit upgraded durability. Note that, after the forth predetermined time has passed, the controller 500 turns off the fuel cell l's electric-power generation operation and the reforming apparatus 2's reforming operation.

[OIOO] (Example No. 8)

[OlOl] A reforming system according to Example No. 8 of the present invention will be hereinafter described with reference to Fig. 5, and is a specific modification of the present reforming system according to Example No. 7. Moreover, it comprises the same constituent elements, and operates and effects the same advantages as those of the present reforming systems according to Example Nos. 1 and 2 fundamentally. That is, Figs. 1 and 2 are also directed to the present reforming apparatus according to Example No. 8. Therefore, it will be described in detail with reference to the drawings whenever applicable. The present reforming system according to Example No. 8 likewise operates the controller 500 to execute the reforming-operation turning-off procedure for turning off the reforming apparatus 2's reforming operation. Prior to carrying out the closing procedure in which the controller 500 shuts off the valve 25a, valve 25b, valve 25d and valve 25m, which constitute the claimed inlet-side valve, and the valve 25e, valve 25h and valve 25f, which constitute the claimed outlet-side valve, the controller 500 performs an extra control, which is described below, for facilitatively activating and recovering the catalyst 37e that is

loaded inside the reforming apparatus 2's CO-oxidizing remover 37 and that is likely to be degraded. Specifically, the controller 500 not only keeps the reforming apparatus 2's reforming operation going on, but also runs the fuel cell l's electric-power generation operation in the minimum-load operation range. Note that the controller 500 carries out the extra control for fourth predetermined time TW, for a time period of from 1 to 60 minutes, preferably from 5 to 30 minutes, for instance. Moreover, it is possible to set the minimum-load operation range so as to cover a range of from 10 to 30%, preferably from 10 to 25%, with respect to the fuel cell l's electric-power-generation output upon the fuel cell l's rated operation that is taken as 100% relatively.

[0102] Fig. 5 is a timing chart that is directed to the present fuel reforming system according to Example No. 8. Note that this timing chart comprises virtually the same constituent elements as those shown in Fig. 3, the timing chart, which is directed to the present fuel reforming system according to Example No. 2, fundamentally. In Fig. 5, time ta specifies time at which the fuel cell l's electric-power generation operation is completed, and at which the controller 500 starts the reforming-operation turning-off procedure. Therefore, at the time ta, the controller 500 closes not only the valves 25a, 25b, 25d and 25m, which make the reforming apparatus 2's claimed inlet valve, but also the valves 25e and 25f, which make the reforming apparatus 2's claimed outlet valve. In Fig. 5, however, note that the controller 500 opens the valve 25h, which also makes the reforming apparatus 2's claimed outlet-side valve, for a time period of δtx. Moreover, time tb specifies time at which the reforming-operation turning-off operation is completed,

and at which the controller 500 starts putting the reforming apparatus 2 on standby. In addition, time tc specifies time at which putting the reforming apparatus 2 on standby is completed, and at which the controller 500 starts actuating the reforming apparatus 2.

[0103] In Fig. 5, time tf, which is prior to the time ta at which the controller 500 closes the valves 25a, 25b, 25d and 25m, which make the claimed inlet-side valve, as well as the valves 25e and 25f, which make the claimed outlet-side valve, specifies time at which the present reforming system according to Example No.8 outputs a termination command for terminating the fuel-cell system' s electric-power generation operation. As illustrated in the drawing, starting at the time tf, that is, before the closing operation in which the controller 500 closes the valves 25a, 25b, 25d and 25m as well as the valves 25e and 25f, the controller 500 operates the fuel cell 1 to output electric power in the minimum-load operation range, for predetermined time TW, for a time period of from 1 to 20 minutes, for instance. Accordingly, from the time tf, the controller 500 reduces the flow volume of the combusting air from VaI to Va2; reduces the flow volume of the combusting fuel from VfI to Vf2; reduces the flow volume of the gaseous reforming raw material from VmI to Vm2; reduces the flow volume of the reforming water from VwI to Vw2; and reduces the flow volume of the oxidizing air from VoI to Vo2. Note herein that the flow volumes designate flow volumes per unit time.

[0104] In the instance described above, it is preferable that the controller 500 can control the flow-volume ratio of Va2 to VaI to fall in a range of from 0 to 0.99 (i.e., Va2/Val = 0-0.99), more preferably from 0.01 to 0.99 (i.e., Va2/Val = 0.01-0.99) , by volume;

can control the flow-volume ratio of Vf2 to VfI to fall in a range of from 0.1 to 0.99 (i.e., Vf2/VfI = 0.1-0.99) by volume; can control the flow-volume ratio of Vm2 to VmI to fall in a range of from 0.1 to 0.99 (i.e., Vm2/Vml = 0.1-0.99) by volume; can control the flow-volume ratio of Vw2 to VwI to fall in a range of from 0.1 to 0.99 (i.e., Vw2/Vwl = 0.1-0.99) by volume; and can control the flow-volume ratio of Vo2 to VoI to fall in a range of from 0.1 to 0.99 (i.e., Vo2/Vol = 0.1-0.99) by volume; for instance. However, in order to inhibit the gaseous reforming raw material from caulking, it is more preferable that the controller 500 can control the flow volume Vm2 so as to exhibit the S/C (i.e., the molar ratio of steam (H ₂ O) to carbon) of 3 or more.

[0105] Thus, regardless of the fact that the controller 500 keeps the reforming apparatus 2's reforming operation running, the controller 500 not only reduces the flow volume of the reformed gas (or hydrogen specifically) that the reforming apparatus 2 generates, but also operates the fuel cell 1 to output electric power in the minimum-load operation range.

[OlOβ] Note herein that, when the controller 500 operates the fuel cell 1 to output electric power in the minimum-load operation range, the controller 500 opens the valves 25e and 25f that make the reforming apparatus 2's claimed outlet-side valve and used to keep running the fuel cell l's electric-power generation operation, though the controller 500 closes the valve 25h that makes the reforming apparatus 2' s claimed outlet-side valve. Accordingly, the controller 500 not only operates to supply the reformed gas to the fuel cell l's fuel electrode 11, but also operates to discharge the anode off gas, which the fuel cell 1 produces, to the reforming apparatus 2's combuster

30 through the off-gas passage 110 via the valve 25f . Consequently, the combuster 30 combusts the combustible components of the anode off gas.

[0107] As described above, in the present reforming systemaccording to Example No. 8, the controller 500 operates to supply the reformed gas as an anode gas to the fuel cell l's fuel electrode 11 at the end stage of terminating the fuel-cell electric-power generation system's electric-power generation operation. Accordingly, it is possible for the present reforming system according to Example No. 8 to discharge the liquid-phased water, which resides in the fuel cell l's membrane electrode assembly, as much as possible. Consequently, upon actuating the fuel cell 1 for the next round of electric-power generation operation, the present reforming system according to Example No. 8 produces such an advantage that it can keep the flooding (i.e., the phenomenon that the liquid-phased water has closed the fuel cell l's flow passages) from occurring.

[0108] In the present reforming system according to Example No. 8 as well, the operating reforming apparatus 2 generates the reformed gas, which comprises hydrogen as the major component. Then, upon terminating the fuel-cell electric-power generation system's electric-power generation operation, the controller 500 turns off the reforming apparatus 2' s reforming operation at the time ta. From this time on, the controller 500 carries out the reforming-operation turning-off procedure. Specifically, at timing tl in the reforming-operation turning-off procedure, the controller 500 first of all shuts off the opened valves 25a, 25b, 25d and 25m, which make the claimed inlet-side valve, as well as the opened valves 25e and 25f, which make the claimed outlet-side valve. Then, at timing t2

that is retarded by the first predetermined time δtx from the timing tl, the controller 500 closes the valve 25h, which also makes the claimed outlet-side valve. That is, the controller 500 has been opening the valve 25h for the first predetermined time δtx, for a time period of from 5 to 20 seconds, for instance, since the timing tl.

[0109] When the controller 500 executes the above-described reforming-operation turning-off procedure, it is possible for the present reforming system according to Example No. 8 to discharge the reformed gas, which generates in the reforming apparatus 2 and comprises hydrogen as the major component, out of the reforming apparatus 2 while keeping the reformed gas residing inside the reforming apparatus 2 as much as possible. Inotherwords, the present reforming system according to Example No. 8 enables the reformed gas, whose major component is hydrogen exhibiting reducing ability, to remain inside the reforming apparatus 2 as much as possible. Therefore, the present reforming system according to Example No. 8 can keep the catalysts 34e, 37e and 5e that are loaded inside the reforming apparatus 2 from being degraded by oxidation.

[Olio] Moreover, the present reforming system according to Example No. 8 actuates the controller 500 to keep the valve 25a, 25b, 25d and 25m, which constitute the reforming apparatus 2's claimed inlet-side valve, closing, that is, to maintain the closed state of the reforming apparatus 2. Under the circumstances, the pressure Pl inside the reforming apparatus 2 increases as the curved section Wl of the characteristic curve Wl specifies, because the water vaporization of liquid-phased water, which resides inside the high-temperature reforming apparatus 2, develops. At timing t4 at

which the pressure Pl increases to predetermined pressure P2, to 5 kPa by gauge pressure, for instance, the controller 500 produces a trigger signal for opening the valve 25h that constitutes the reforming apparatus 2's claimed outlet-side valve, and thereby the valve 25h opens instantaneously for a short period of time δt (or sixth predetermined time) . Thus, the controller 500 releases high pressure inside the reforming apparatus 2 (that is, the controller 500 carries out a first pressure releasing process) , thereby inhibiting the pressure inside the reforming apparatus 2 from increasing excessively. Note that, even thereafter, the pressure Pl inside the reforming apparatus 2 increases as the curved sections WIb and WIc of the characteristic curve Wl specify, because the high-temperature reforming apparatus 2's remaining heat further turns the liquid-phased water into water vapor. Moreover, in addition to the timing t4, at timings t5 and t6 at which the pressure Pl increases to the predetermined pressure P2, the controller 500 produces the trigger signal again, and accordingly the valve 25h reopens instantaneously for a short period of time δt to release high pressure inside the reforming apparatus 2 (that is, the controller 500 carries out a second pressure releasing process), thereby further inhibiting the pressure inside the reforming apparatus 2 from increasing excessively. Consequently, the present reforming system according to Example No. 8 enables the reforming apparatus 2 not to be provided with superfluously enhanced pressure resistance.

[θlll] In addition, the present reforming systemaccordingto Example No.8 carries out a forcible cooling process for cooling the reforming apparatus 2 forcibly, because it actuates the controller 500 to keep

the pump 27c running continuously from the initial stage of the reforming-operation turning-off procedure so that the pump 27c keeps supplying air to the reforming apparatus 2's combuster 30 through the combusting-air passage 73. In this instance, while cooling the reforming apparatus 2, the air, which the pump 27c supplies to the combuster 30, flows through in the following order: the combustion passage 32, the combustion passage 33 and the combusted-exhaust-gas passage 250, and is then discharged to the outside. Thus, since the air, which is used for cooling the reforming apparatus 2, is warmed, the reforming apparatus 2's evaporator 36 undergoes temperature increment for a while for a time period of from the time ta to the time tb so that the CO-oxidizing remover 37, which neighbors on the evaporator 36, also undergoes temperature increment. Therefore, upon turning off the reforming apparatus 2' reforming operation, the present reforming system according to Example No. 8 enables the pump 27c to function as a temperature-maintaining element for letting the evaporator 36 and CO-oxidizing remover 37 undergo temperature increment or for inhibiting them from undergoing temperature decrement.

[0112] Moreover, as time elapses, the temperature Tl, which the reforming apparatus 2's reformer 34 exhibits, decreases. At timing t8 at which the temperature Tl of the reformer 34 decreases to lower-temperature-side predetermined temperature, to a temperature of from 100 to 200 ⁰ C, for instance, to 150 ⁰ C, especially, the present reforming system according to Example No.8 produces a trigger signal foroperating the controller 500 to turnoff thepump 27c. Accordingly, the air supply to the reforming apparatus 2's combuster 30, which is done through the combusting-air passage 73, is turned off. Thus,

the controller 500 turns off the forcible cooling process for cooling the reforming apparatus 2 forcibly. In addition, as illustrated in Fig. 5, at the timing t8, the controller 500 opens the valves 25a and 25b, which constitute the claimed inlet-side valve, while operating the pump 27b. Consequently, the gaseous reforming raw material is supplied into the inside of the reforming apparatus 2 through the reforming-raw-material passage 62c once, or a plurality of times depending on specific cases, for predetermined time tr. Thus, the pressure Pl inside the reforming apparatus 2, which a pressure sensor detects, increases to predetermined pressure P3, to 20 kPa approximately, for instance, as the curved section WIr of the characteristic curve Wl specifies. Thereafter, since the cooling of the reforming apparatus 2 develops so that the condensation of water vapor progresses, the pressure Pl, which the pressure sensor detects, decreases gradually and eventually to appropriate negative pressure Pe, to -15 kPa approximately, for instance, as the curved section WIe of the characteristic curve Wl specifies. Then, the reforming apparatus 2 is put on standby by the controller 500. As a result, the present reforming system according to Example No. 8 enables the reforming apparatus 2 to exhibit inner pressure that hardly turns into excessive negative pressure.

[0113] Asdescribedabove, in the present reforming systemaccording to Example No. 8, the controller 500 operates to supply the gaseous reforming raw material into the inside of the reforming apparatus 2 when the temperature Tl of the reforming apparatus 2's reformer 34 decreases to a predetermined temperature at which the gaseous reforming raw material does not undergo caulking in the reformer 34. For example, note that the predetermined temperature can

preferably fall in a range of from 100 to 200 X^ ₁ and can be 150 °C, especially. Hence, the present reforming system according to Example No .8 enables the gaseous reforming rawmaterial not to undergo caulking in the reformer 34, and thereby it is possible to upgrade the durability of the reformer 34.

[0114] Moreover, in the present reforming systemaccording to Example No. 8, the controller 500 finishes putting the reforming apparatus 2 on standby at the time tc, and then commences the start-up of the reforming apparatus 2. Upon starting up the reforming apparatus 2, the controller 500 not only activates the pump 27b but also opens the valves 25a and 25b, which constitute the claimed inlet-side valve, by a predetermined period of time δtm, for from 0.5 to 15 seconds, for instance, after the time tc. Note that the time δtm is not limited to this specific time period at all. Thus, the controller 500 supplies the gaseous reforming raw material into the inside of the reforming apparatus 2' s reformer 34 so that the reforming apparatus 2 exhibits increasing inner pressure. Under the circumstances that the reforming apparatus 2 exhibits the thus increased inner pressure, if the controller 500 does not appreciate decrement in the pressure Pl inside the reforming apparatus 2 for predetermined time TK, for 300 seconds, for instance, it judges that no gas vents out of the piping of the present reforming system according to Example No. 8 so that the piping is under normal condition. In addition, when the piping is judged to be under normal condition upon starting the reforming apparatus 2's reforming operation, it is allowable to rid the controller 500 of the operation for monitoring the reforming apparatus 2 by stopping the electric-power supply to the controller 500 while it turns off the reforming apparatus 2's operation and

puts the reforming apparatus 2 on standby for the next round of operation, thereby cutting down the controller 500' s standby electric power.

[0115] (Example No. 9)

[0116] Fig.6 is directed to a reforming system according to Example No. 9 of the present invention. Since the present reforming system according to Example No. 9 comprises the same constituent elements as those of the present reforming systems according to Example Nos. 1 and 2 basically, and since it operates and effects the same advantages as those of the present reforming system according to Example No. 8 fundamentally, Figs.1 and 2 will be similarly applied to describing it whenever necessary. The present reforming system according to Example No. 9 will be hereinafter described while focusing on the constituent elements that differ from those of the present reforming system according to Example No.8. As shown in Fig.5 that is directed to the present reforming system according to Example No. 8, the controller 500 closes the valve 25h, which constitutes the claimed outlet-side valve, at the timing t2 that retards from the timing tl by the predetermined time δtx. However, as shown in Fig. 6, the present reforming system according to Example No. 9 has done away with the retardation by the predetermined time δtx. Therefore, in the present reforming system according to Example No. 9, the controller 500 closes the valves 25a, 25b, 25d and 25m, which constitute the claimed inlet-side valve, as well as the valves 25h, 25e and 25f, which constitute the claimed outlet-side valve, simultaneously starting at the timing tl (or time ta) .

[0117] (Example No. 10)

[Ollθ] Fig.7 is directed to a reforming system according to Example

No. 10 of the present invention. Note that the present reforming system according to Example No. 10 comprises the same constituent elements as those of the present reforming systems according to Example Nos. 1 and 2, and operates and effects the same advantages as they do fundamentally. As illustrated in Fig. 7, in addition to the constituent elements of the present reforming systems according to Example Nos. 1 and 2, the present reforming system according to Example No. 10 further comprises an annular heat insulating layer 700. The heat insulating layer 700 is formed as a ring-shape, and is disposed between the reforming apparatus 2's evaporator 36 and CO-oxidizing remover 37. Moreover, the heat insulating layer 700 is provided with a lower end 70Od. The heat insulating layer 700 canmake the CO-oxidizing remover 37 to be likely to exhibit maintained temperature when the controller 500 turns off the reforming apparatus 2's reforming operation, and even when the evaporator 36 exhibits decreasing temperature. As a result, the heat insulating layer 700 enables the CO-oxidizing evaporator 37 to keep exhibiting temperature as high as the recovery temperature of the catalyst 37e that is loaded inside the CO-oxidizing remover 37. Under the circumstances, since hydrogen resides inside the CO-oxidizing remover 37, the catalyst 37e is subjected to reducing treatment. Thus, the present reforming system according to Example No. 10 can inhibit the catalyst 37e from being degraded by oxidation, and thereby the catalyst 37e exhibits enhanced durability.

[0119] (Additional Embodiments)

[0120] Although the above-described present reforming system according to Example No. 1 comprises the reforming apparatus 2 into which the evaporator 36 is incorporated integrally, it is allowable

to dispose the evaporator 36 independently of the reforming apparatus 2. Moreover, although it comprises the reforming apparatus 2 into which the heat exchanger 4 is incorporated integrally, it is allowable to dispose the heat exchanger 4 independently of the reforming apparatus 2. In addition, in the present reforming system according to Example No. 1, the reformer 34 is disposed up above, and the CO shifter 5 is disposed down below. However, note that the disposition of the reformer 34 and CO shifter 5 is not limited to such a disposition, and that it is allowable to dispose them the other way around. Moreover, the present invention is not at all limited to the above-described examples, and can be performed by appropriately making many changes and modifications to them without departing from the spirit or scope of the present invention. For example, it is possible to grasp the following engineering ideas from the above descriptions on the present invention.

[0121] (Extra Subject Matter No. 1)

A reforming system, comprising: a reforming apparatus comprising a reformer for generating reformed gas containing hydrogen by means of reacting gaseous raw material for reforming with water; and a controller for controlling the reforming apparatus; the reforming apparatus further comprising: a heater for heating the reformer; an evaporator for generating water vapor to be supplied to the reformer; and a CO reducer receiving heat transfer from the reformer and comprising a built-in catalyst for reducing CO component being contained in the reformed gas that the reformer generates; when the controller carries out reforming-operation

turning-off procedure for turning off the reforming apparatus's reforming operation after operating the reforming apparatus to generate the reformed gas; the controller keeping the heater of the reforming apparatus heating the reformer for second predetermined time to slow down the CO reducer' s temperature-decrement rate while suppressing the evaporator' s temperature decrement, thereby subjecting the built-in catalyst of the CO reducer to reducing treatment in such a state that hydrogen resides in the CO reducer. [0122] (Extra Subject Matter No. 2)

The reforming system according to Extra Subject Matter No. 1 further comprising: an inlet-side valve being disposed on an upstream side with respect to the reforming apparatus, thereby supplying the gaseous rawmaterial for reforming to the reformer of the reforming apparatus; an outlet-side valve being disposed on a downstream side with respect to the reforming apparatus, thereby discharging the reformed gas being generated at the reformer of the reforming apparatus out of the reforming apparatus; and when the controller carries out reforming-operation turning-off procedure for turning off the reforming apparatus's reforming operation after operating the reforming apparatus to generate the reformed gas; the controller carrying out closing procedure for closing both of the inlet-side valve and the outlet-side valve; and the controller carrying out opening/closing procedure in which the controller not onlymaintains the inlet-side valve' s closed state but also opens the outlet-side valve when pressure inside the

reforming apparatus increases topredeterminedpressure, and inwhich the controller thereafter closes the outlet-side valve.

INDUSTRIAL APPLICABILITY

[0123] The present reforming system can avail itself of being reforming apparatus that is used for making fuel-cell system and hydrogen generating system.