JP2002121003A - Control of raw material feed quantity in reformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease a discharge quantity of unreacted raw fuel when starting a reforming device. SOLUTION: At the time of starting a reformer 30, the feed quantity of the raw fuel and water are controlled so that the ratio (C/S) of the mol number C of carbon contained in the raw fuel (e.g. methanol) supplied to the reformer 30 to the mol number of water S is smaller than a prescribed reasonable value (e.g. about 0.5) in the normal operation of the reformer 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control technique for starting a fuel reformer for generating a hydrogen-rich fuel gas from a raw fuel containing a hydrocarbon compound.

[0002]

2. Description of the Related Art A reformer generates a hydrogen-rich fuel gas from a raw fuel containing a hydrocarbon compound by utilizing a steam reforming reaction. The supply amount of the raw fuel and the supply amount of water to the reformer are respectively controlled to appropriate values in consideration of various chemical reactions in the reformer.

[0003] As a technique for controlling the supply amounts of raw fuel and water to a reformer, for example, a technique described in Japanese Patent Application Laid-Open No. H11-307110 is known. In this method, the molar ratio (S / C) between the steam supplied to the reformer and the carbon in the raw fuel is adjusted according to the change in the load of the fuel cell. As a result, it is possible to obtain an appropriate amount of hydrogen gas according to the load fluctuation of the fuel cell.

[0004]

However, in the above-mentioned prior art, the problem at the time of starting the reformer has not been considered. That is, when the reformer is started, the temperature of the reforming catalyst is not sufficiently high, so that the reforming reaction is not sufficiently activated. As a result, at startup,
Even if a large amount of raw fuel is charged, there is a problem that most of the raw fuel is discharged from the reformer without being reacted.

In particular, methanol has a boiling point of about 65 ° C., which is much lower than that of water. Therefore, when the methanol reformer is started, a methanol-rich raw material gas is supplied to the reforming catalyst. Therefore, in the methanol reformer,
The problem that a large amount of unreacted methanol was discharged at the time of startup was significant. However, such a problem is not limited to methanol, but is a problem common to reformers for raw fuels containing hydrocarbon compounds having a boiling point lower than that of water.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to reduce the amount of unreacted raw fuel discharged from the reformer when the reformer is started. It aims to provide technology.

[0007]

In order to achieve the above object, a fuel reforming apparatus according to the present invention comprises a reformer including a reforming catalyst, a hydrocarbon-based reformer having a boiling point lower than that of water. A raw fuel supply unit for supplying a raw fuel containing a compound to the reformer; and a water supply unit for supplying water used for a steam reforming reaction in the reforming catalyst to the reformer. And, during at least a part of the period when the reformer is started, the number of moles C of carbon contained in the raw fuel supplied from the raw fuel supply unit and the water supplied from the water supply unit. Control for controlling the raw fuel supply unit and the water supply unit such that the value of the ratio (C / S) to the number of moles S is smaller than a predetermined appropriate value during steady operation of the reformer. And a unit.

[0010] According to this configuration, since the ratio of the raw fuel is reduced when the reformer is started, it is possible to reduce the amount of unreacted raw fuel discharged.

The control unit controls the raw fuel supply unit and the water supply unit such that the value of the ratio (C / S) monotonously increases when the reformer is started. It may be.

According to this configuration, since the ratio of the raw fuel gradually increases monotonously, the amount of the raw fuel corresponding to the increase in the activation of the reforming reaction can be supplied to the reformer, and the unreacted fuel can be supplied. Raw fuel emissions can be reduced.

It is preferable that the raw fuel contains a hydrocarbon compound having a boiling point lower than that of water as a main component. For example, methanol can be used as the raw fuel.

The problem of unreacted raw fuel emissions at start-up is more serious for hydrocarbons having a lower boiling point than water, so hydrocarbons having a lower boiling point than water, such as methanol, are the major constituents. The effect of the present invention is particularly remarkable when the raw fuel is used.

The present invention can be realized in various modes. For example, a fuel reformer and its control method, a fuel cell system and its control method, and the functions of those methods or devices are realized. Program, a recording medium on which the computer program is recorded, a data signal including the computer program and embodied in a carrier wave, and the like.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described based on examples in the following order. A. First embodiment: B. Other examples: C.I. Modification:

A. First Embodiment FIG. 1 is an explanatory diagram showing a configuration of a fuel cell system as a first embodiment of the present invention. The fuel cell system 200 includes a raw fuel tank 10 for storing methanol and a water tank 20 for storing water.
And fuel gas (“reformed gas”)
, A fuel cell 40,
And a controller 50. The reformer 30 includes a vaporizing section 32 for vaporizing the reforming raw material, a heating section 34 for supplying heat to the vaporizing section 32, a reforming section 36 containing a reforming catalyst, and carbon monoxide in the reformed gas. And a selective oxidizing unit 38 for performing selective oxidation for reducing the amount of oxidization. Note that the vaporizing section 32 and the heating section 34 may be collectively referred to as an “evaporating section”.

A raw fuel supply passage 102 is provided in the raw fuel tank 10.
Are connected, and a water supply path 108 is connected to the water tank 20. The raw fuel supply passage 102 branches into two branch passages 104 and 106. First branch channel 104
Merges with the water supply path 108 and the flow path 11 after the merger.
0 is connected to the vaporizing section 32. On the other hand, the second branch channel 106 is connected to the heating unit 34. A flow meter 51 and a pump 52 are provided in the first branch channel 104, and a flow meter 53 and a pump 54 are also provided in the second branch channel 106.
Is provided. The water meter 108 and the pump 56 are also provided in the water supply path 108.

The raw fuel tank 10, raw fuel supply path 102 and its first branch flow path 104, flow meter 51
And the pump 52 constitute a raw fuel supply unit in the present invention. Further, the water tank 20 and the water supply path 108
, The flow meter 55, and the pump 56 constitute a water supply unit in the present invention.

Methanol and water are sucked out by pumps 52 and 56, respectively, and are mixed and vaporized in the vaporizing section 32.
Will be introduced. This mixture is hereinafter referred to as “reforming raw material”. The reforming raw material is vaporized in the vaporization section 32 to become steam (methanol vapor and steam), and is supplied to the reforming section 36. This gaseous reforming raw material ("reforming raw material gas"
) Is converted into a hydrogen gas-rich fuel gas HRG by a chemical reaction in the reforming unit 36 and the selective oxidizing unit 38. The chemical reaction in the reforming section 36 will be described later.

The fuel gas HRG generated in the reformer 30
Is introduced into the fuel gas passage 42 in the fuel cell 40 via the fuel gas passage 112. The air AR4 is supplied to the air passage 44 in the fuel cell 40 by the air pump 46.
0 is supplied. As the air pump 46, for example, a blower can be used. In the fuel cell 40, power is generated by an electrochemical reaction between hydrogen in the fuel gas HRG and oxygen in the air AR40, and as a result, hydrogen in the fuel gas HRG is consumed.

Exhaust path 1 for fuel exhaust gas from fuel cell 40
14 is returned to the heating section 34 of the reformer 30. The heating unit 34 burns hydrogen in the fuel exhaust gas and supplies the heat to the vaporization unit 32. As the heating unit 34, a device that promotes a combustion reaction of fuel exhaust gas or methanol using a noble metal catalyst such as a platinum catalyst or a palladium catalyst, or a device that burns fuel exhaust gas or methanol using a burner may be used. it can. In the vaporizing section 32, the reforming raw material is vaporized by the heat given from the heating section 34. When the amount of heat generated by the combustion of the fuel exhaust gas is insufficient, methanol as raw fuel is supplied to the heating unit 34 via the pump 54. The heating unit 34 further includes a first
The heating air AR34 is supplied by the air supply unit 64 of the air conditioner. The air supply unit 64 includes an air pump 64a
, A pressure gauge 64b, and an electric valve 64c. A similar second air supply unit 66 is provided to the reforming unit 36.
Is supplied to the mixing chamber 36a on the upstream side of the air AR36.

The reforming section 36 is provided with a temperature sensor 92 for measuring the temperature of the reforming catalyst. Further, an oxygen concentration sensor 94, a carbon monoxide concentration sensor 96, and a raw fuel sensor 98 (a methanol concentration sensor in this embodiment) are provided in a fuel gas flow path 112 between the reformer 30 and the fuel cell 40. ing. The controller 50 includes these sensors 92, 94, 96, 98, the flow meters 51, 53,
The control of the fuel cell system 200 is performed using the measurement values measured by the plurality of sensors including the control signal 55 as a control input. In FIG. 1, for the sake of illustration, the controller 50 only shows connections to some components (sensors and pumps), and illustration of connections to other components is omitted.

The main chemical reactions used in each part of the reformer 30 are as follows. In the reforming section 36, the following steam reforming reaction of methanol mainly occurs.

CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ −49.5 (kJ / mol) (1)

As the catalyst for the steam reforming reaction of methanol, for example, a copper-zinc catalyst can be used. The air A is supplied to the reforming unit 36 by the second air supply unit 66.
When R36 is charged, the following partial oxidation reaction also occurs in the reforming section 36.

CH ₃ OH + (１ ／) O ₂ → CO ₂ + 2H ₂ +189 (kJ / mol) (2)

The steam reforming reaction of the above formula (1) is an endothermic reaction, and the partial oxidation reaction of the formula (2) is an exothermic reaction. When the reformer 30 is started, the temperature of the reforming catalyst can be raised by utilizing the heat generated by the partial oxidation reaction. In addition, during the steady operation of the reformer 30, by performing both at an appropriate ratio, it is possible to maintain the reforming unit 36 at an appropriate operating temperature. The air A supplied to the reforming unit 36
Since R36 is used in the above partial oxidation reaction, it is hereinafter referred to as "partial oxidation air".

The steam reforming reaction of the above formula (1) is
For example, it can be considered as a result of the following two reactions.

CH ₃ OH → CO + 2H ₂ -90.0 (kJ / mol) (3) CO + H ₂ O → CO ₂ + H ₂ +40.5 (kJ / mol) (4)

However, part of the carbon monoxide generated by the reaction of the formula (3) is supplied from the reforming unit 36 to the selective oxidizing unit 38 without being converted into carbon dioxide. Therefore, in the selective oxidation section 38, the concentration of carbon monoxide is reduced by the following selective oxidation reaction.

CO + (1/2) O ₂ → CO ₂ +279.5 (kJ / mol) (5)

As a catalyst for the selective oxidation reaction, a noble metal catalyst such as a platinum catalyst or a ruthenium catalyst, an aluminum catalyst, or the like can be used. The gas that has passed through the selective oxidation section 38 is supplied to the fuel cell 40 as a hydrogen-rich fuel gas HRG. As is well known, the reason why the concentration of carbon monoxide is reduced in the selective oxidation section 38 is that carbon monoxide has a poisoning effect on the platinum catalyst in the fuel cell 40 and reduces the electromotive force of the fuel cell 40. It is because it lowers.

By the way, as understood from the above equation (1),
In an ideal steam reforming reaction, one mole of water molecule is required for one mole of carbon atom. However, it is known that in an actual reforming reaction, adding a little more water increases the reforming efficiency (production rate of hydrogen molecules). The ratio of the number of moles of water molecules to 1 mole of carbon atoms in the raw material gas supplied to the reforming section 36 is called a steam-carbon ratio (S / C). When the reformer 30 using methanol as a raw fuel is in a steady operation state, the steam-carbon ratio (S
The appropriate value of / C) is, for example, about 2.0.

FIG. 2 is an explanatory diagram showing the state of controlling the input amount of the reforming raw material in the comparative example. FIG. 2A shows a change over time in the amount of water input when the reformer 30 is started. Here, “starting the reformer” means starting from a room temperature state. FIG. 2 (B) shows the amount of methanol charged, FIG. 2 (C) shows the reciprocal of the steam-carbon ratio (S / C), and FIG. 2 (D) shows the outlet methanol concentration. Note that the vertical axis in FIGS. 2A, 2B, and 2D is
As for the relative value scale, the vertical axis in FIG. 2C is the absolute value scale. The input amounts of water and methanol were calculated from the flow rates measured by the respective flow meters 55 and 51 (FIG. 1). The reciprocal of the steam / carbon ratio (S / C) is calculated from the input amounts of water and methanol. The outlet methanol concentration is measured by the methanol concentration sensor 98.

In this comparative example, at time t0
When the operation of the reformer 30 is started, heating is performed until time t1.
Only the section 34 is operated to raise the temperature. Temperature of heating unit 34
Is higher to some extent, from time t1, water and methanol
The supply to the vaporizer 32 is started. Water input and methano
From the time t1 are substantially constant values LW1 and LW1.
M1. Also, steam car
The reciprocal of the Bonn ratio (S / C) also has a constant value (C
/ S)₁ (= 0.5). This (C / S) ₁ The value of the
Is the steam-carbon ratio (S /
C) corresponds to an appropriate value (about 2.0).

By the way, at time t1, since the temperature of the reforming catalyst in the reforming section 36 is not so high, the time t1
Even if a large amount of methanol is introduced after 1, most of the methanol does not cause a chemical reaction in the reforming section 36. In particular, since methanol has a lower boiling point than water, methanol-rich fuel gas is supplied to the reforming unit 36, and a large amount of unreacted methanol is discharged from the reformer 30 at the time of startup.
As a result, as shown in FIG. 2D, a phenomenon occurs in which the outlet methanol concentration sharply rises from time t1.

Further, since the methanol-rich fuel gas is supplied to the reforming section 36, a part of the unreacted methanol is supplied to the inside of the reforming section 36 (particularly, the rear end side of the reforming catalyst) and the selective oxidation section 38. The phenomenon of condensing and storing inside also occurs. The methanol condensed in this way evaporates gradually when the temperature of the reforming catalyst rises and a sufficient reforming reaction starts to occur, but the concentration of methanol at the outlet gradually decreases until this evaporation is completed. That is, in this comparative example, even after the temperature of the reforming catalyst has increased and a sufficient reforming reaction has started, the outlet methanol concentration does not readily decrease,
A phenomenon occurs in which fuel gas containing considerable unreacted methanol is supplied to the fuel cell 40.

FIG. 3 is an explanatory diagram showing the manner of controlling the input amount of the reforming raw material in the first embodiment of the present invention. As in the case of FIG. 2, the heating unit 34 is heated from time t0 to time t1, and the supply of water and methanol is started from time t1. Also in the first embodiment, the input amount of water is maintained at a substantially constant value LW1 from time t1, but the input amount of methanol is different from that of the comparative example. That is, the input amount of methanol is substantially zero at the time t1, then increases substantially linearly, and reaches a substantially constant value LM1 at the time t2.

The reciprocal of the steam-carbon ratio (S / C) shown in FIG. 3 (C) changes according to the change in the amount of methanol charged. That is, this value (C / S) is substantially zero at time t1, thereafter increases almost linearly, and reaches a substantially constant value (C / S) ₁ at time t2.
This value (C / S) ₁ is about 0.5, which is an appropriate value of the steam-carbon ratio (S / C) during steady operation (about 2.
0).

As shown in FIG. 3D, in the first embodiment, the outlet methanol concentration increases from time t1,
The peak remains at a lower value than the comparative example (FIG. 2D). Also, it can be understood that the outlet methanol concentration is rapidly decreasing even after reaching the peak. Accordingly, the high-quality fuel gas HRG having a low methanol concentration is supplied from the reformer 30 to the fuel cell 4 earlier than the comparative example.
0 can be supplied.

The change in outlet methanol concentration as shown in FIG. 3D is presumed to be caused by the following phenomenon. That is, although the temperature of the reforming catalyst is not sufficiently high immediately after the start of the introduction of methanol, since a small amount of methanol is supplied, a considerable portion of the supplied methanol is subjected to partial oxidation reaction (formula (2)) or the like. It is used for an exothermic reaction to raise the temperature of the reforming catalyst. Therefore, even immediately after the start of the introduction of methanol, not much unreacted methanol is discharged. When the amount of unreacted methanol is small, the amount of methanol condensed inside the reformer 30 is also small. Thereafter, when the temperature of the reforming catalyst gradually increases, the amount of methanol used for the partial oxidation reaction and the steam reforming reaction increases, so that even if the amount of methanol is gradually increased, the unreacted methanol is excessively increased. It does not increase. Then, when the temperature of the reforming catalyst substantially reaches a temperature suitable for the steady operation state around time t2, the amount of unreacted methanol rapidly decreases. Further, since the amount of unreacted methanol condensed in the reforming catalyst immediately after the start-up is extremely small as compared with the comparative example, when the temperature of the reforming catalyst almost reaches the temperature in the steady operation state around time t2, the outlet The methanol concentration will also drop rapidly.

The first embodiment also has the following advantages. The first advantage is that the amount of unreacted methanol discharged can be reduced, so that methanol as a raw fuel can be saved. Therefore, it is possible to increase the power generation efficiency of the fuel cell system 200.

A second advantage is that the time required for starting the reformer 30 can be reduced. That is, in the first embodiment, since the outlet methanol concentration decreases earlier than in the comparative example, it is possible to supply the high-quality fuel gas HRG to the fuel cell 40 from an earlier point in time to start power generation.

A third advantage is that since the amount of methanol charged immediately after the start of methanol charging is suppressed to a small amount, a sharp rise in the temperature of the reforming catalyst due to a partial oxidation reaction can be prevented. If methanol is excessively introduced into the reforming catalyst, the temperature of the reforming catalyst may rise sharply due to the heat generated by the partial oxidation reaction. Further, the reforming catalyst tends to deteriorate easily in a high temperature and methanol-rich environment. In the first embodiment, since the amount of methanol charged immediately after the start of the introduction of methanol is suppressed to a small amount, it is possible to prevent a high-temperature, methanol-rich environment and prevent deterioration of the reforming catalyst.

A fourth advantage is that the amount of carbon monoxide generated during startup can be reduced. When the methanol-rich raw material gas is injected into the reforming section 36, methanol is decomposed as shown in the above formula (3), and carbon monoxide is generated. In the first embodiment, since the amount of methanol in the raw material gas supplied to the reforming unit 36 at the time of startup is smaller than in the conventional case, it is possible to reduce the amount of carbon monoxide generated at the time of startup.

FIG. 4 is an explanatory diagram showing the manner of controlling the feed rate of the reforming raw material in the second embodiment. In the second embodiment,
The input amount of water is the same as that of the first embodiment, and the time change of the input amount of methanol is different from that of the first embodiment. That is, in the second embodiment, the value LM0 of the methanol input amount at the time t1 is set to a value considerably lower than the value LM1 in the steady operation state (FIG. 4B). However, at time t1
Thereafter, the amount of methanol charged increases almost linearly and reaches a substantially constant value LM1 at time t2. The value of the reciprocal of the steam carbon ratio (S / C) also changes accordingly, and at time t1, a predetermined value (C / S) ₀ higher than ₀
, And thereafter increases almost linearly and reaches a substantially constant value (C / S) ₁ at time t2. The graph of the outlet methanol concentration in the second embodiment is not shown.

Also in the second embodiment, methanol
In the period immediately after the start of introduction, the steam carbon ratio (S /
The value of the reciprocal of C) is changed to an appropriate value (C /
S) ₁ Is set smaller than that of the first embodiment.
There are almost the same effects and advantages.

FIG. 5 is an explanatory view showing the state of controlling the input amount of the reforming raw material in the third embodiment. The third embodiment also differs from the first embodiment only in the time change of the methanol input amount. That is, in the third embodiment, from time t1 to time t
In the period of 2, the methanol input amount is the value L in the steady operation state.
It is kept at a constant value LM0 lower than M1, and at time t2
, The value is stepwise increased to the value LM1 in the steady operation state. It can be understood that the reciprocal value of the steam-carbon ratio (S / C) also changes according to this (FIG. 5 (C)). Note that such a step-like change is not limited to one time, and may be performed a plurality of times.

Also in the third embodiment, in the period immediately after the start of the introduction of methanol, the reciprocal value of the steam-carbon ratio (S / C) is set to be smaller than the appropriate value (C / S) ₁ in the steady operation. It is set small. Therefore, the third
The embodiment also has substantially the same effects and advantages as those of the first and second embodiments.

The third embodiment is common to the first and second embodiments in that the reciprocal of the steam-carbon ratio (S / C) is monotonically increased. Here, that a certain value “increases monotonically” means that the value does not substantially decrease and only a period in which the value increases and a period in which the value is kept at a constant value are present.

However, in the third embodiment, since the methanol input amount and the steam / carbon ratio (S / C) change stepwise at the time t2, the temperature of the reforming catalyst is sufficiently increased by the time t2. It may not be possible to do so. Therefore, from the viewpoint of shortening the start-up time of the reformer, the value of the reciprocal of the steam / carbon ratio (S / C) is continuously increased as in the above-described first and second embodiments. A control method is preferred.

As in the second and third embodiments,
When the reciprocal of the steam-carbon ratio (S / C) immediately after the start of the introduction of methanol is set to a non-zero value (C / S) ₀ , this initial value (C / S) ₀ It is preferable to set the value to about 1/2 or less of an appropriate value. For example, the range of the appropriate value of the steam carbon ratio (S / C) in the steady operation state is about 1.5 to about 2.
When it is 0, its reciprocal (C / S) range is about 0,0.
50 to about 0.67. In this case, the value (C / S) ₀ of the reciprocal of the steam-carbon ratio (S / C) immediately after the start of the introduction of methanol is preferably a value of about 0.25 or less. As described above, if the input amount immediately after the start of the input of methanol is set to a relatively low value, the above-described effects and advantages by suppressing the input amount of methanol at the time of startup can be exhibited more efficiently. is there.

FIG. 6 is an explanatory view showing the manner of controlling the input amount of the reforming raw material in the fourth embodiment. In the fourth embodiment,
The time change of the methanol input amount is the same as that of the first embodiment, but the time change of the water input amount is different from that of the first embodiment. That is, in the fourth embodiment, the amount of water input at time t1 is set to a value LW0 lower than the value LW1 in the steady operation state, and the amount of water input also increases linearly from time t1 to time t2. ing. Steam carbon ratio (S
It can be seen that the value of the reciprocal of / C) also changes in a curve according to this (FIG. 6C).

In this fourth embodiment, too,
In the period immediately after the start of introduction, the steam carbon ratio (S /
The value of the reciprocal of C) is changed to an appropriate value (C /
S) ₁ Is set to be smaller than
There are substantially the same effects and advantages as in the third embodiment.

C. Modifications: The present invention is not limited to the above-described examples and embodiments, and can be carried out in various modes without departing from the gist thereof. For example, the following modifications are also possible. is there.

C1. Modification 1 As a raw fuel for the reformer, various hydrocarbon-based fuels such as alcohol other than methanol, natural gas, gasoline, aldehyde, and ether can be used. That is, even when a raw fuel other than methanol is used, the value of the ratio (C / S) of the number of moles C of carbon and the number of moles S of water in the raw fuel is improved when the reformer is started. It suffices that the input amounts of water and raw fuel are controlled so as to be smaller than a predetermined appropriate value during the steady operation of the plaster.

Gasoline has a boiling point of about 40 ° C. to 22 ° C.
It contains a very large number of hydrocarbons in the 0 ° C. range, but also contains quite a few hydrocarbons with boiling points below 100 ° C.
Therefore, the effects of the present invention can be obtained in a gasoline reformer. However, the present invention is particularly effective when applied to a reformer for a raw fuel mainly composed of a hydrocarbon compound having a lower boiling point than water, such as a methanol reformer.

C2. Modification 2: In each of the above-described embodiments,
Although the period from the time t1 to t2 is set as the activation period of the reformer 30, the definition of the activation period of the reformer 30 has considerable arbitrariness. For example, a period from time t2 to a certain time can be defined as a starting period, and a period until the reforming catalyst reaches a certain temperature can be defined as a starting period. Therefore, in the present invention, the value of the ratio (C / S) of the number of moles C of carbon and the number of moles S of water in the raw fuel is at least partly at the time of starting the reformer as described above. It only has to be controlled. However, as described in each of the above-described embodiments, it is preferable to apply the present invention during an initial period including the starting point of the input of the raw fuel into the reformer during the starting period of the reformer.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a fuel cell system as a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a state of controlling the amount of input of a reforming raw material in a comparative example.

FIG. 3 is an explanatory diagram showing a state of controlling the input amount of the reforming raw material in the first embodiment.

FIG. 4 is an explanatory diagram showing a state of controlling the input amount of a reforming raw material in a second embodiment.

FIG. 5 is an explanatory diagram showing a state of controlling the input amount of a reforming raw material in a third embodiment.

FIG. 6 is an explanatory diagram showing a state of controlling the input amount of a reforming raw material in a fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Raw fuel tank 20 ... Water tank 30 ... Reformer 32 ... Vaporization part 34 ... Heating part 36 ... Reforming part 36a ... Mixing chamber 38 ... Selective oxidation part 40 ... Fuel cell 42 ... Fuel gas passage 44 ... Air passage 46 ... Air pump 50 ... Controller 51,53,55 ... Flow meter 52,54,56 ... Pump 64,66 ... Air supply unit 64a, 66a ... Air pump 64b, 66b ... Pressure gauge 64c, 66b ... Electric valve 92 ... Temperature sensor 94: oxygen concentration sensor 96: carbon monoxide concentration sensor 98: raw fuel sensor (methanol concentration sensor) 102: raw fuel supply passage 104, 106 ... branch passage 108 ... water supply passage 110 ... passage 112 ... fuel gas passage 114: exhaust passage 200: fuel cell system

Claims (5)

[Claims] 1. A fuel reformer for producing a hydrogen-rich fuel gas from a raw fuel containing a hydrocarbon-based compound, comprising: a reformer including a reforming catalyst; A raw fuel supply section for supplying the reformer, a water supply section for supplying water used for the steam reforming reaction in the reforming catalyst to the reformer, At least for some periods,
The value of the ratio (C / S) of the number of moles C of carbon contained in the raw fuel supplied from the raw fuel supply unit to the number of moles S of water supplied from the water supply unit is changed. So that it becomes smaller than a predetermined appropriate value during steady operation of the
A fuel reforming apparatus comprising: a control unit that controls the raw fuel supply unit and the water supply unit. 2. The fuel reforming apparatus according to claim 1, wherein the control unit is configured to control the engine so that the value of the ratio (C / S) monotonically increases when the reformer is started. A fuel reformer for controlling a fuel supply unit and the water supply unit. 3. The fuel reformer according to claim 2, wherein the raw fuel mainly comprises a hydrocarbon compound having a boiling point lower than that of water. 4. The fuel reformer according to claim 3, wherein the raw fuel is methanol. 5. A method for controlling a reformer for producing a hydrogen-rich fuel gas from a raw fuel containing a hydrocarbon compound having a boiling point lower than that of water, the method comprising: In some periods,
Number of moles C of carbon in the raw fuel supplied to the reformer
Controlling the supply amounts of the raw fuel and water such that the value of the ratio (C / S) of the water and the mole number S of water becomes smaller than a predetermined appropriate value during steady operation of the reformer. A control method characterized by the above-mentioned.