JP2003212508A - Water supply control method for reforming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the transient response of a reforming system. <P>SOLUTION: In a method of controlling supply of water in the reforming system provided with a reformer 2 for producing a hydrogen enriched gas by gasifying raw material and reforming, a shifter 4 for removing carbon monoxide contained in a production gas produced with the reformer 2 by a shift reaction and a main injector 13 for supplying water to the raw material and fuel, the humidity of the production gas is detected with a humidity sensor 27 and the supply quantity of water with the main injector 13 is controlled corresponding to the detected humidity. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply control method in a reforming system including a reformer and a shifter, and more particularly to a reforming system capable of controlling the water concentration of gas flowing into the shifter. The present invention relates to the water supply control method.

[0002]

2. Description of the Related Art As a method of supplying fuel gas to a fuel cell, a raw fuel containing hydrocarbons such as methanol and gasoline is reformed into a hydrogen-rich fuel gas (hereinafter abbreviated as hydrogen-rich gas) by a reforming system. In some cases, this hydrogen-rich gas is supplied as the fuel gas for the fuel cell (JP 2000-302408 A, etc.). For example, in a reforming system that reforms gasoline, which is a raw fuel, into hydrogen-rich gas, steam generated in an evaporator and gasoline, which is a raw fuel, are mixed and supplied to the reformer, and the reformer reforms the gasoline. Quality reaction to reform to hydrogen-rich gas.
This hydrogen-rich reformed gas contains carbon monoxide (CO) generated by a side reaction, and if the CO concentration in the reformed gas supplied to the fuel cell is high, the anode of the fuel cell will There is a risk that CO will be poisoned and the output of the fuel cell will decrease. Therefore, in this reforming system, a heat exchanger, a shifter, and a CO remover are provided in this order downstream of the reformer, the reformed gas is lowered to a predetermined temperature by the heat exchanger, and then the reformed gas is changed by the shifter. CO in the reformed gas is reduced by converting CO in the reformed gas into carbon dioxide (CO ₂ ) by a shift reaction and further oxidizing the remaining CO into CO ₂ by oxidizing the CO in the CO remover. The reformed gas is supplied to the anode of the fuel cell as fuel gas (hydrogen rich gas).

A fuel cell vehicle equipped with such a reforming system and a fuel cell is required to have a quick response to transient fluctuations. In this case, the responsiveness of the fuel cell body is extremely excellent, and it can be said that the transient responsiveness of the fuel cell vehicle is determined by the transient responsiveness of the reforming system.

[0004]

By the way, in the conventional reforming system, the injection ratio of water and hydrocarbon fuel (gasoline in the previous example), whether the reforming system is in the steady state or in the transient state, That is, steam / carbon mol
The amount of supplied water and the amount of fuel were controlled so that the ratio (hereinafter, abbreviated as S / C ratio) was constant. However, since the latent heat of vaporization differs between water and fuel, the substantial S of the gas flowing into the reformer (hereinafter referred to as the reformer inlet gas) during a transient state.
The / C ratio was not stable, and as a result, there was a problem that the CO concentration of the reformed gas flowing out from the reformer (hereinafter abbreviated as reformer outlet gas) became unstable. More specifically, in the reformer, CO ₂ and hydrogen (H) generated by the reforming reaction cause a side reaction, and a reversible reaction as shown in [Chemical Formula 1] occurs.

[0005]

[Chemical 1]

The equilibrium constant Kp in this reversible reaction is expressed as shown in [Equation 1]. FIG. 16 shows the relationship between the equilibrium constant Kp and temperature.

[0007]

[Equation 1]

Here, for example, when the output of the reforming system is increased (in the case of a reforming system for a fuel cell vehicle, this corresponds to acceleration of the vehicle), water and fuel are increased at the same S / C ratio as in the steady state. However, as described above, since water is less likely to evaporate due to the difference in latent heat of vaporization, the substantial S / C ratio of the reformer inlet gas is fuel-rich (in other words, water). Concentration decreases). This phenomenon becomes more remarkable as the output increase rate (vehicle acceleration rate) is higher. If the temperature in the reformer is controlled to be constant, the equilibrium constant Kp becomes fixed, and when the concentration of water in the reformer decreases, the equilibrium shifts to the CO rich side, and CO
The concentration increases.

FIG. 6 is a graph in which the behavior of the water concentration of the gas flowing out from the heat exchanger (hereinafter, abbreviated as heat exchanger outlet gas) when the output is increased is experimentally obtained and the experimental result is graphed. The solid line in the figure shows the case where the water and fuel supply amounts are controlled at the same S / C ratio as in the steady state as described above. From this experimental result, it can be seen that the water concentration of the heat exchanger outlet gas decreases as the output signal increases. Further, FIG. 7 is a graph in which the behavior of the CO concentration of the gas flowing out from the shifter (hereinafter, abbreviated as shifter outlet gas) when the output is increased is experimentally obtained, and the experimental result is graphed. Shows the case where the supply amounts of water and fuel are controlled at the same S / C ratio as in the steady state as described above. From this experimental result, it can be seen that the CO concentration of the shifter outlet gas increases as the output signal increases.

When the CO concentration of the shifter outlet gas rises in this way, the load on the CO remover increases, and therefore the CO remover must supply an excessive amount of oxidizing air in order to remove a large amount of CO. However, if this happens, even hydrogen generated as fuel for the fuel cell will be burned, resulting in a decrease in system efficiency.

Further, when the output of the reforming system decreases (decelerates) after the output rapidly increases (after deceleration), the water retained in the evaporator does not evaporate when the output suddenly increases and evaporates with a delay. Therefore, even if the water and fuel are reduced at the same S / C ratio as in the steady state when the output is reduced, the substantial S / C ratio of the reformer inlet gas becomes water richer than in the steady state. As a result, the equilibrium in the reformer shifts to the CO lean side, and the CO concentration decreases. In this case, keep the S / C ratio constant and
When the air for O-oxidation is supplied, the substantial amount of air becomes excessive and hydrogen is burned, which also reduces the efficiency. Therefore, the present invention provides a water supply control method for a reforming system capable of stabilizing the water concentration of gas flowing into a shifter.

[0012]

In order to solve the above-mentioned problems, the first invention of this application is to hydrogenate a raw fuel (for example, gasoline in the embodiments described later) by gasifying and then reforming it. Included in a reformer (for example, the reformer 2 in the embodiment described later) that generates various gases and a generated gas (for example, the reformed gas in the embodiment described later) generated by the reformer. A shifter for removing carbon monoxide by a shift reaction (for example, shifter 4 in the embodiment described later) and a first water supply means for supplying water to the raw fuel (for example, water in the embodiment described later). Supply pipe 11, first control valve 12, main injector 1
3) and a water supply control method in a reforming system comprising: detecting the humidity of the generated gas, and controlling the amount of water supplied by the first water supply means according to the detected humidity. And

With this configuration, when the detected humidity of the generated gas is low, the water concentration of the generated gas can be increased by increasing the amount of water supplied by the first water supply means, and the detected generated gas can be increased. When the humidity of the gas is high, the water concentration of the produced gas can be lowered by reducing the amount of water supplied by the first water supply means. Therefore, it becomes possible to always stabilize the moisture concentration of the produced gas flowing into the shifter.

A second invention of this application is a reformer (for example, which will be described later) that gasifies a raw fuel (for example, gasoline in the embodiment described later) and then reforms it to produce a hydrogen-rich gas. Reformer 2 in the embodiment
And a shifter for removing carbon monoxide contained in the produced gas (for example, the reformed gas in the embodiment described later) generated by the reformer by a shift reaction (for example, the shifter 4 in the embodiment described below). And a first water supply means for supplying water to the raw fuel (for example, a water supply pipe 11, a first control valve 12, and a main injector 13 in an embodiment described later). In the water supply control method according to the second aspect, a second water supply means (for example, a water supply pipe 17, a second control valve 18, a sub-injector 19 in an embodiment described later) for supplying water to the generated gas is provided, Detecting the humidity of the generated gas,
It is characterized in that the amount of water supplied by the second water supply means is controlled according to the detected humidity.

With this configuration, when the detected humidity of the generated gas is low, the water concentration of the generated gas flowing into the shifter can be increased by increasing the amount of water supplied by the second water supply means. it can. Therefore, it becomes possible to stabilize the moisture concentration of the generated gas flowing into the shifter.

In the first invention or the second invention, when the water supply amount is controlled to increase as the generated gas humidity decreases, the lower the detected product gas humidity, the more the water supply. Since the amount can be rapidly increased, the water concentration of the product gas flowing into the shifter can be rapidly increased.

A third invention of this application is a reformer (for example, which will be described later) which gasifies a raw fuel (for example, gasoline in the embodiment described later) and then reforms it to produce a hydrogen-rich gas. Reformer 2 in the embodiment
And a shifter for removing carbon monoxide contained in the produced gas (for example, the reformed gas in the embodiment described later) generated by the reformer by a shift reaction (for example, the shifter 4 in the embodiment described below). And a first water supply means for supplying water to the raw fuel (for example, a water supply pipe 11, a first control valve 12, and a main injector 13 in an embodiment described later). In the water supply control method according to the first aspect, the rate of change in the amount of generated gas required for the reforming system is calculated, and the amount of water supplied by the first water supply means is controlled according to the rate of change. .

With such a configuration, it is possible to determine from the calculated rate of change of the produced gas amount whether the reforming system is in the output increasing or the output decreasing, and when it is determined that the output is increasing. By increasing the amount of water supplied by the first water supply means, it is possible to increase the water concentration of the produced gas, and when it is determined that the output is decreasing, the amount of water supply by the first water supply means is increased. By reducing the amount, the water concentration of the produced gas can be lowered. Therefore, it becomes possible to always stabilize the moisture concentration of the produced gas flowing into the shifter.

A fourth invention of this application is a reformer (for example, which will be described later) which gasifies a raw fuel (for example, gasoline in the embodiment described later) and then reforms it to produce a hydrogen-rich gas. Reformer 2 in the embodiment
And a shifter for removing carbon monoxide contained in the produced gas (for example, the reformed gas in the embodiment described later) generated by the reformer by a shift reaction (for example, the shifter 4 in the embodiment described below). And a first water supply means for supplying water to the raw fuel (for example, a water supply pipe 11, a first control valve 12, and a main injector 13 in an embodiment described later). In the water supply control method according to the second aspect, a second water supply means (for example, a water supply pipe 17, a second control valve 18, a sub-injector 19 in an embodiment described later) for supplying water to the generated gas is provided, It is characterized in that the rate of change in the amount of generated gas required for the reforming system is calculated, and the amount of water supplied by the second water supply means is controlled in accordance with this rate of change.

With such a configuration, it is possible to determine from the calculated rate of change of the produced gas amount whether the reforming system is at the time of output increase or output decrease, and when it is determined to be the output increase time, By increasing the amount of water supplied by the water supply means No. 2, it is possible to increase the water content of the generated gas flowing into the shifter. Therefore, it becomes possible to always stabilize the moisture concentration of the produced gas flowing into the shifter.

In the third invention or the fourth invention, when the rate of change of the generated gas amount is obtained from the rate of change of the accelerator opening of the vehicle in which the reforming system is mounted, The reforming system can be made to follow the transient state quickly.

Further, in the third invention or the fourth invention, when the increase in the water supply amount is controlled to increase as the rate of change of the generated gas amount increases in the positive direction, the generated gas amount increases. Since the water supply amount can be rapidly increased as the rate of change in the positive direction increases, the water concentration of the product gas flowing into the shifter can be rapidly increased.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a water supply control method for a reforming system according to the present invention will be described below with reference to the drawings of FIGS. 1 to 15. The reforming system in each of the embodiments described below is an aspect as a reforming system that generates fuel gas to be supplied to a fuel cell as an energy generator mounted on a fuel cell vehicle,
As described above, the reforming system reforms a raw fuel containing hydrocarbons such as gasoline or methanol into hydrogen-rich gas by steam reforming or the like, and supplies the hydrogen-rich gas to the fuel cell.

[First Embodiment] First, a first embodiment of the present invention will be described with reference to the drawings of FIGS. 1 to 8. FIG. 1 shows a schematic configuration of the reforming system. The reforming system in this embodiment mainly includes an evaporator 1, an autothermal reformer 2, a heat exchanger 3, a shifter 4, and a CO remover 5 with a heat exchanger, and serves as a raw fuel. The gasoline is reformed into hydrogen-rich gas and supplied to the fuel cell 50. The fuel cell 50 is a solid polymer electrolyte membrane fuel cell, and generates electricity by an electrochemical reaction between hydrogen in the fuel gas supplied to the anode and oxygen in the air as the oxidant gas supplied to the cathode. To do.

Water is supplied to the evaporator 1 from the main injector 13 via the water supply pipe 11 and the first control valve 12, and reforming air is supplied via the air supply pipe 14. Has become. Main injector 13
The amount of water supplied from the first control valve 12 can be controlled based on a command from the control device 90. In the embodiment, the water supply pipe 1
1, the first control valve 12, the main injector 13 is the first
It constitutes the water supply means. Further, the evaporator 1 is provided with a catalytic combustor (not shown) inside, and the hydrogen off gas and the air off gas discharged from the fuel cell 50 are supplied to the off gas pipe 2.
Introduced into the catalytic combustor through 3, 24 and burned, the heat generated at this time vaporizes the water introduced into the evaporator 1 into steam and heats the reforming air.

The steam generated in the evaporator 1 and the heated reforming air are mixed and supplied from the evaporator 1 to the reformer 2 via the raw material gas supply pipe 15 and the heat exchanger 3. To be done. Further, gasoline as a raw fuel is injected by the fuel supply device 6 into a predetermined portion of the raw material gas supply pipe 15 upstream of the heat exchanger 3 and is injected into the raw material gas supply pipe 15. The generated gasoline is vaporized by the heat of steam and reforming air to become raw fuel gas,
Raw gas supply pipe 1 mixed with steam and reforming air
Flow through 5. Hereinafter, a mixed fluid of steam, reforming air, and raw fuel gas (gasoline) is referred to as a raw material gas. The injection amount of gasoline injected into the raw material gas supply pipe 15 can be controlled by the fuel supply device 6 based on a command from the control device 90. When the raw material gas passes through the heat exchanger 3, the raw material gas is heated by exchanging heat with the high-temperature reformed gas flowing out of the reformer 2 in a non-contact manner, and liquid gasoline is present in the raw material gas. If so, vaporize this.

The reformer 2 has a reforming catalyst inside,
Due to the catalytic action of this reforming catalyst, partial oxidation and steam reforming are performed in the reformer 2, and as a result, the gasoline (raw fuel gas) in the raw material gas is converted to a hydrogen-rich reformed gas (produced gas). Be quality. Examples of the reforming catalyst include noble metal catalysts such as Pt and Rh, and Ni catalysts. It should be noted that this reformed gas contains several% of CO generated by the side reaction.
The degree is included.

The reformed gas reformed by the reformer 2 is supplied to the heat exchanger 3 via the reformed gas supply pipe 16. Since the reformed gas is extremely hot and cannot be supplied to the downstream shifter 4 at this high temperature, the reformed gas is exchanged with the raw material gas flowing through the raw material gas supply pipe 15 in the heat exchanger 3 in a non-contact manner. Cool the quality gas. At the same time,
As described above, the exhaust gas of the reformed gas is used to heat the raw material gas.

In the middle of the reformed gas supply pipe 16, a sub-injector 1 is provided via a water supply pipe 17 and a second control valve 18.
The water can be supplied from 9 and the amount of supplied water can be controlled by the second control valve 18 based on a command from the control device 90. In addition, in this embodiment, the water supply pipe 17, the second control valve 18, and the sub-injector 19 constitute second water supply means.

The reformed gas cooled by the heat exchanger 3 is supplied to the shifter 4 via the reformed gas supply pipe 20. As described above, since the reformed gas discharged from the reformer 2 has a high CO concentration and cannot be directly supplied to the anode of the fuel cell 50, CO is removed by the shifter 4. The shifter 4 has a shift catalyst inside, and a shift reaction is performed inside the shifter 4 by the catalytic action of the shift catalyst, so that a large amount of CO in the reformed gas is converted to CO ₂ . Examples of the shift catalyst include Pt-based or CuZn catalysts.

The reformed gas from which CO has been removed by the shifter 4 passes through the reformed gas supply pipe 21 and the CO remover 5
Is supplied to. The CO remover 5 includes a CO removing catalyst that selectively oxidizes CO, and a small amount of CO remaining in the reformed gas is oxidized to CO ₂ by the catalytic action of the CO removing catalyst. As a CO removal catalyst, platinum (P
Examples of the oxidation catalyst include t) and ruthenium (Ru). Further, the CO remover 5 has a structure in which a heat exchanger 5 a is built in, and the reformed gas is cooled while passing through the CO remover 5. The reformed gas thus removed of CO and cooled to a predetermined temperature is supplied from the CO remover 5 to the anode of the fuel cell 1 as hydrogen-rich gas through the hydrogen-rich gas supply pipe 22.

Further, the reformed gas supply pipe 20 is connected with a bypass pipe 25 for branching and flowing a part of the reformed gas flowing through the reformed gas supply pipe 20, and the bypass pipe 25 is connected to the bypass pipe 25. A gas cooler 26 for cooling the reformed gas flowing through 25 to a predetermined temperature and a humidity sensor 27 for detecting the humidity of the reformed gas cooled by the gas cooler 26 are provided.
That is, the humidity sensor 27 detects the humidity of the reformed gas flowing out from the heat exchanger 3.

In this reforming system, when the flow rate of the hydrogen-rich gas generated in the reforming system (in other words, the fuel gas supplied from the CO remover 5 to the fuel cell 50 as the fuel gas) is in a steady state. , The main injector 13 so that the ratio of the water supplied from the main injector 13 to the evaporator 1 and the fuel injected from the fuel supply device 6 to the raw material gas supply pipe 15, that is, the S / C ratio becomes a constant value. The amount of water injection from the fuel injection device and the amount of fuel injection from the fuel supply device 6 are controlled. In this steady state, water injection from the sub-injector 19 is not performed.

However, even when the flow rate of the hydrogen-rich gas generated in the reforming system is in a transient state, the water injection amount from the main injector 13 and the fuel injection from the fuel supply device 6 are kept at the same S / C ratio as in the steady state. If the amount is controlled, as described above, the CO concentration of the reformed gas (hereinafter, abbreviated as shifter outlet gas) flowing out from the shifter 4 becomes unstable, which causes a problem as described above. is there. That is, when the output is increased (when the vehicle is accelerated), the CO concentration in the shifter outlet gas is increased and the load on the CO remover 5 is increased, so that the oxidizing air is supplied to the CO remover 5 in excess of the steady state. Must be done, and as a result, even hydrogen in the reformed gas is burned, resulting in poor system efficiency.

The inventor of the present invention, as described above, has a high CO concentration in the shifter outlet gas when the output is increased.
It was speculated that this was caused by the low water concentration of the reformed gas flowing in (in other words, the reformed gas flowing out of the reformer 2). Therefore, in order to support this, C of the reformed gas (hereinafter abbreviated as shifter inlet gas) flowing into the shifter 4
When the O concentration was kept constant and only the water concentration of the reformed gas was changed to measure the CO concentration of the shifter outlet gas, the experimental results shown in FIGS. 2 and 3 were obtained. From the results of this experiment, it is understood that, when the shift catalysts are compared at the same temperature, the higher the water concentration is, the lower the CO concentration of the shifter outlet gas is.
For example, at the shift catalyst temperature T1, the CO concentration of the shifter outlet gas is 1.4% when the moisture concentration of the shifter inlet gas is 20%, while the CO concentration of the shifter inlet gas is 30%. The CO concentration of the gas is 0.
It drops to 8%.

Therefore, in the first embodiment, the CO concentration of the shifter outlet gas is made constant by controlling the moisture concentration of the shifter inlet gas to be constant. Then, in order to control the moisture concentration of the shifter inlet gas at a constant level, the humidity of the shifter inlet gas is detected by the humidity sensor 27, and water is jetted from the sub-injector 19 or from the main injector 13 according to the detection result. It was decided to reduce (including stopping) the water injection amount of.

Next, the water supply control of the reforming system in this embodiment will be described with reference to the flow chart of FIG. The flowchart shown in FIG. 4 shows a water supply control routine, and this water supply control routine is executed by the ECU 90 at regular time intervals after the completion of warming up of the reforming system.

First, the humidity of the shifter inlet gas detected by the humidity sensor 27 is read (step S10).
1) Based on the humidity value, referring to the humidity / S / C map shown in FIG. 5, the substantial S / C of the gas flowing into the reformer 2 (hereinafter referred to as reformer inlet gas). The ratio is calculated (step S102). The humidity / S / C map of FIG. 5 shows the substantial S / C of the reformer inlet gas obtained experimentally in advance.
It is created based on the relationship between the C ratio and the humidity of the shifter inlet gas, and the lower the humidity, the smaller the S / C ratio.

Next, it is determined whether or not the substantial S / C ratio of the reformer inlet gas calculated in step S102 is smaller than the target S / C ratio (step S103). The target S / C ratio is S / C in the steady state of the reforming system.
It is the same as the C ratio. If the determination result in step S103 is "YES" (smaller than the target S / C ratio: fuel rich), water injection from the sub-injector 19 is executed (step S104), and the execution of this routine is once terminated. To do. In this case, the water injection amount from the sub-injector 19 is the water shortage amount calculated based on the difference between the substantial S / C ratio of the reformer inlet gas calculated in step S102 and the target S / C ratio. And

The lower the humidity of the shifter inlet gas, the smaller the substantial S / C ratio of the reformer inlet gas, and the larger the difference between the substantial S / C ratio and the target S / C ratio becomes. The shortage of water will increase. Therefore, the lower the humidity of the shifter inlet gas, the larger the amount of water injected from the sub-injector 19. As a result, the moisture concentration of the reformed gas flowing into the shifter 4 can be rapidly increased, and the transient response of the reforming system is improved.

On the other hand, if the determination result in step S103 is "NO" (not smaller than the target S / C ratio), the substantial S / C ratio of the reformer inlet gas calculated in step S102 is the target S / C ratio. It is determined whether it is larger than the / C ratio (step S105). If the determination result in step S105 is "YES" (greater than the target S / C ratio: water rich), the water injection amount from the main injector 13 is reduced (step S106), and the execution of this routine is once terminated. . Here, in order to reduce the water injection amount, the water injection amount is set to zero (that is, the main injector 13
The case of stopping the water injection from) is also included. In this case, the reduction amount of water injection from the main injector 13 is calculated based on the difference between the substantial S / C ratio of the reformer inlet gas calculated in step S102 and the target S / C ratio. If the determination result in step S105 is "NO" (not larger than the target S / C ratio), step S105
Since the substantial S / C ratio of the reformer inlet gas calculated in 102 matches the target S / C ratio, the current state is maintained and the execution of this routine is once terminated.

The alternate long and short dash lines in FIGS. 6 and 7 are the results of measuring the water concentration of the shifter inlet gas and the CO concentration of the shifter outlet gas when the water supply control is executed as described above. From the experimental results shown in FIG. 6, it can be seen that when the water supply control is performed as described above, the water concentration of the shifter inlet gas is much more stable than before even when the output signal increases. Further, from the experiment shown in FIG. 7, it can be seen that when the water supply control is performed as described above, the CO concentration of the shifter outlet gas becomes much more stable than before even when the output signal increases. That is, when the moisture concentration of the shifter inlet gas becomes stable, the shifter 4 is always operated under the optimum condition, and as a result, the CO concentration of the shifter outlet gas becomes stable.

If the CO concentration of the shifter outlet gas can be stabilized even in the transient state, the CO remover 5 can sufficiently exhibit the CO removing performance with the same supply amount of oxidizing air as in the steady state. And as a result,
It is possible to generate a hydrogen-rich gas having substantially the same hydrogen concentration and CO concentration as in the regular state, and to supply the hydrogen-rich gas to the fuel cell 50. That is, by executing the above-described water supply control, the reforming system can stabilize the system efficiency even during a transition. In addition, NO. In the water supply control pattern table shown in FIG. 1 shows the water supply control pattern in this 1st Embodiment.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to the drawing of FIG. In the above-described first embodiment, when the substantial S / C ratio of the reformer inlet gas deviates to the fuel rich from the target S / C ratio, the main injector 1 has the same S / C ratio as the steady state.
By controlling the water injection amount from the fuel injection device 3 and the fuel injection amount from the fuel supply device 6, the water injection from the sub-injector 19 is executed to stabilize the water concentration of the shifter inlet gas and reduce the CO 2 of the shifter outlet gas. I try to stabilize the concentration.

On the other hand, in the second embodiment, when the substantial S / C ratio of the reformer inlet gas deviates to the fuel rich from the target S / C ratio, the main injector 13 outputs the fuel. S / of the water injection amount and the fuel injection amount from the fuel supply device 6
By intentionally shifting the C ratio to the water-rich side, the amount of water evaporated in the evaporator 1 is positively increased, whereby the substantial S / C ratio of the reformer inlet gas is increased to the target S / C ratio. The reformer 2 and the system downstream thereof are operated under the same operating conditions as in the steady state.

The configuration of the reforming system according to the second embodiment is the same as that of the system configuration according to the first embodiment except that the sub-injector 19 is removed, and the other configurations are exactly the same. 1 shall be used.
Water supply control of the reforming system according to the second embodiment will be described with reference to the flowchart of FIG. Figure 9
Similarly to the first embodiment, the water supply control routine shown in (7) is also executed by the ECU 90 at regular time intervals after the completion of warming up of the reforming system.

First, the humidity of the shifter inlet gas detected by the humidity sensor 27 is read (step S20).
1) Based on the humidity value, the substantial S / C ratio of the reformer inlet gas is calculated with reference to the humidity / S / C map shown in FIG. 5 (step S202). Next, step S202.
It is determined whether or not the substantial S / C ratio of the reformer inlet gas calculated in step 3 is smaller than the target S / C ratio (step S2).
03). The target S / C ratio is the same as the S / C ratio when the reforming system is in a steady state.

The determination result in step S203 is "Y.
In the case of “ES” (smaller than the target S / C ratio: fuel rich), the water injection amount from the main injector 13 is increased from the injection amount in the steady state (step S20).
4), S / C ratio (hereinafter referred to as apparent S / C ratio) calculated from the amount of water injected from the main injector 13 and the amount of fuel injected from the fuel supply device 6 is controlled to be water-rich Then, the execution of this routine is once ended. In this case, the increase amount of water injection from the main injector 13 is
It is calculated based on the difference between the substantial S / C ratio of the reformer inlet gas calculated in step S202 and the target S / C ratio.

The lower the humidity of the shifter inlet gas, the smaller the substantial S / C ratio of the reformer inlet gas, and the larger the difference between the substantial S / C ratio and the target S / C ratio becomes. The shortage of water will increase. Therefore, the lower the humidity of the shifter inlet gas, the greater the increase amount of water injection from the main injector 13. As a result, the moisture concentration of the reformed gas flowing into the shifter 4 can be quickly increased, and
The transient response of the reforming system is improved. On the other hand, if the determination result in step S203 is "NO" (not smaller than the target S / C ratio), the substantial S / C ratio of the reformer inlet gas calculated in step S202 is the target S / C ratio. It is determined whether it is larger than (step S205).

The determination result in step S105 is "Y.
If it is "ES" (greater than the target S / C ratio: water rich), the amount of water injection from the main injector 13 is reduced (step S206), and the apparent S / C ratio is controlled to be fuel rich, The execution of this routine is once terminated. Here, the reduction of the water injection amount includes the case where the water injection amount is set to zero (that is, the water injection from the main injector 13 is stopped). In this case, the reduction amount of water injection from the main injector 13 is determined by the substantial S / C ratio of the reformer inlet gas calculated in step S202 and the target S /
It is calculated based on the difference from the C ratio. If the determination result in step S205 is "NO" (not larger than the target S / C ratio), the substantial S / C ratio of the reformer inlet gas calculated in step S202 is equal to the target S / C ratio. Therefore, the current state is maintained and the execution of this routine is once terminated.

According to the water supply control of the second embodiment, the substantial S / C ratio of the reformer inlet gas is made equal to the steady-state S / C ratio even when the reforming system is in transition. Since it can be controlled, the reformer 2, the shifter 4, and the CO remover 5 can be operated under the same operating conditions as in the steady state, and as a result, a hydrogen-rich gas having substantially the same hydrogen concentration and CO concentration as in the steady state can be produced. The hydrogen-rich gas can be generated and can be supplied to the fuel cell 50.
That is, the reforming system can stabilize the system efficiency even during a transient period. In addition, NO. In the water supply control pattern table shown in FIG. 5 shows a water supply control pattern in the second embodiment.

It is also possible to combine the water supply control described in the first embodiment with the water supply control described in the second embodiment, and the water supply control pattern table shown in FIG. NO. 2 to NO. 4 is an example of the combination. Hereinafter, each combination pattern will be described. In FIG. In the water supply control pattern shown in 2, the water supply control is executed only by the water injection from the main injector 13 in the steady state, and the water injection from the main injector 13 is performed during the transition in which the apparent S / C ratio changes to fuel rich. And the water injection from the sub-injector 19 is performed, and the main injector 13 is in a transient state when the apparent S / C ratio changes to water-rich.
Reduce or stop water injection from.

In FIG. In the water supply control pattern shown in FIG. 3, water injection from the main injector 13 and water injection from the sub-injector 19 are executed in a steady state, and when the apparent S / C ratio changes to fuel rich, the main injector 13 The water injection from the sub-injector 19 is stopped, the water injection from the sub-injector 19 is increased, and at the transient time when the apparent S / C ratio changes to water-rich, the main injector 13 and the sub-injector 1
The water injection from 9 is reduced or stopped.

In FIG. In the water supply control pattern shown in FIG. 4, the water injection from the main injector 13 and the water injection from the sub-injector 19 are executed in a steady state, and when the apparent S / C ratio changes to fuel rich, the main injector 13 Further, the amount of water injection from the sub-injector 19 is increased, and during a transition in which the apparent S / C ratio changes to water-rich, the amount of water injection from the main injector 13 and the sub-injector 19 is decreased or stopped. These NO. 2 to NO. According to the water supply control pattern of No. 4, as in the case of the first embodiment (NO.1 water supply control pattern) or the second embodiment (NO.2 water supply control pattern), the shifter inlet is also provided. The water concentration of the gas can be stabilized, and the system efficiency in the transient state can be stabilized as in the steady state.

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to the drawings of FIGS. The amount of generated gas required for the reforming system, that is, the output of the reforming system is determined by the operating state of the fuel cell 50, and the operating state of the fuel cell 50 when the reforming system is installed in a fuel cell vehicle. Since it is determined by the accelerator opening (or output command value),
It is possible to detect the output change of the reforming system (change of the produced gas amount) from the change of the accelerator opening, and the output change rate of the reforming system can be obtained from the change rate of the accelerator opening.

Therefore, in the third embodiment, the humidity of the shifter inlet gas is detected and the water supply control is performed based on the humidity value as in the first embodiment or the second embodiment. Instead of performing, calculate the rate of change of the accelerator opening, determine whether the reforming system is in transition (when the output is increasing or decreasing) based on the rate of change, and
Water injection of the main injector 13, the sub-injector 19, or both is controlled according to the rate of change.

FIG. 10 is a schematic configuration diagram of the reforming system according to the third embodiment, and is different from the system configuration of the first embodiment shown in FIG. 1 in that the bypass pipe 25 and the gas cooler 26 are provided. The humidity sensor 27 is not provided and the output signal of the accelerator opening sensor 80 provided in the fuel cell vehicle is input to the control device 90. Since other configurations are the same as the system configuration shown in FIG. 1,
The same reference numerals are given to the same aspect parts and the description thereof will be omitted. The main injector 13 and the sub-injector 19 in this embodiment both control the injection amount by controlling the duty ratio of the valve opening time.

Next, in the water supply control pattern table shown in FIG. A case where the water supply amount is controlled by the water supply control pattern 1 will be described with reference to the flowchart of FIG. Similarly to the first embodiment, the water supply control routine shown in FIG. 11 is also executed by the ECU 90 at regular time intervals after the completion of warming up of the reforming system. First, step S30
1, the rate of change of the accelerator opening is calculated based on the accelerator opening signal of the accelerator opening sensor 80. The rate of change of the accelerator opening has a positive (plus) value when the vehicle is accelerating, and has a negative (minus) value when the vehicle is decelerating.

Next, in step S302, it is determined whether the rate of change in accelerator opening calculated in step S301 is equal to or greater than a preset positive upper limit value. If the determination result in step S302 is "YES" (equal to or greater than the positive upper limit value), it is determined that the fuel cell vehicle is in the acceleration state and the reforming system is in the transient state of output increase, and the process proceeds to step S303. .

In step S303, referring to the sub-injector duty ratio map shown in FIG. 12, based on the rate of change of the accelerator opening calculated in step S301,
The duty ratio of the sub-injector 19 is calculated. The sub-injector duty ratio map of FIG. 12 is created by performing an experiment in advance, and is set so that the duty ratio increases as the rate of change of the accelerator opening increases. Since the change rate of the accelerator opening is large means that the output change rate of the reforming system is large, the water injection amount from the sub-injector 19 is increased as the output change rate of the reforming system is larger. This allows
The moisture concentration of the reformed gas flowing into the shifter 4 can be quickly increased, and the transient response of the reforming system is improved.

Next, in step S304, referring to the sub-injector / injection time map shown in FIG. 13, from the sub-injector 19 based on the time during which the vehicle is in the accelerated state (hereinafter referred to as "acceleration time"). Calculate the water injection time. The sub-injector / injection time map of FIG. 13 is created by performing an experiment in advance, and is set so that the injection time becomes shorter as the acceleration time becomes longer.

Next, in step S305, the duty ratio calculated in step S303 is used to calculate the duty ratio in step S304.
The water injection is executed from the sub-injector 19 for the injection time calculated in step 1, and the execution of this routine is once ended.

On the other hand, if the result of the determination in step S302 is "NO" (the rate of change of the accelerator opening is smaller than the positive upper limit value), the flow advances to step S306 to change the accelerator opening calculated in step S301. It is determined whether the rate is less than or equal to the negative lower limit value. If the result of the determination in step S306 is "YES" (less than or equal to the negative lower limit value), it is determined that the fuel cell vehicle is in the decelerating state and the reforming system is in the transition period of output reduction, and thus step S30.
Proceed to 7.

In step S307, the duty ratio reduction rate of the main injector 13 is calculated based on the rate of change of the accelerator opening calculated in step S301 with reference to the main injector duty ratio reduction rate map shown in FIG. The main injector / duty ratio reduction rate map of FIG. 14 is created by performing an experiment in advance, and is set so that the duty ratio reduction rate decreases as the negative change rate of the accelerator opening increases. .

Next, in step S308, referring to the main injector / reduction time map shown in FIG.
The time that the fuel cell vehicle holds the deceleration state (hereinafter,
Based on the deceleration time), the execution time of the water reducing injection from the main injector 13 (hereinafter referred to as the reduction time) is calculated. The main injector / weight reduction time map of FIG. 15 is created by conducting an experiment in advance, and is set so that the weight reduction time becomes shorter as the deceleration time becomes longer.

Next, in step S309, the product obtained by multiplying the duty ratio of the main injector 13 in the steady state by the duty ratio reduction rate calculated in step S307 is set as the duty ratio of the main injector 13.
The water injection from the main injector 13 is executed for the weight reduction time calculated in step S308, and the execution of this routine is once ended.

When the result of the determination in step S306 is "NO", the rate of change of the accelerator opening is in the range larger than the negative lower limit value and smaller than the positive upper limit value. It is determined that the routine is in the steady state, and the execution of this routine is once terminated.

By performing the water supply control as described above, the reforming system can stabilize the water concentration of the shifter inlet gas even during a transient time, and the shifter 4 can be operated under optimum conditions at all times. As a result, the CO concentration of the shifter outlet gas becomes stable. As a result, the CO remover 5 can exhibit sufficient CO removal performance with the same supply amount of oxidizing air as in the steady state, and as a result, the hydrogen-rich gas having substantially the same hydrogen concentration and CO concentration as in the steady state is obtained. Can be generated, and the hydrogen-rich gas can be supplied to the fuel cell 50. That is,
By executing the water supply control described above, the reforming system can stabilize the system efficiency even during a transient period. Further, the output change rate of the reforming system (change rate of generated gas) is obtained from the change rate of the accelerator opening, so that the reforming system can quickly follow the transient state of the vehicle. The transient response of the system is improved.

Even when the water supply control is performed based on the rate of change of the accelerator opening (the rate of change of the amount of generated gas) as in the third embodiment, NO in the water supply control pattern table shown in FIG. ． 2 to NO. It is possible to adopt the water supply control pattern of No. 5.

[Other Embodiments] The present invention is not limited to the above-described embodiments. For example, the raw fuel is not limited to gasoline, but methanol or methane can be used. The rate of change of the amount of generated gas can also be obtained from the rate of change of the amount of electric power taken out from the fuel cell.

[0071]

As described above, according to the first aspect of the invention, a reformer for gasifying a raw fuel and then reforming it to produce a hydrogen-rich gas, and a reformer produced by the reformer are provided. A water supply control method for a reforming system, comprising: a shifter for removing carbon monoxide contained in a product gas by a shift reaction; and a first water supply means for supplying water to the raw fuel. By detecting the humidity of the gas and controlling the amount of water supplied by the first water supply means in accordance with the detected humidity, generation that flows into the shifter even if the operating state of the reforming system changes Since the water concentration of the gas can be stabilized, the shifter can always be operated under optimum conditions, and the CO concentration of the gas treated by the shifter can be constantly stabilized, which is an excellent effect.

Further, according to the second aspect of the invention, a reformer for gasifying the raw fuel and then reforming it to produce a hydrogen-rich gas, and a reformer included in the produced gas produced by the reformer In a water supply control method in a reforming system comprising a shifter for removing carbon oxide by a shift reaction and a first water supply means for supplying water to the raw fuel, water is supplied to the produced gas. A second water supply means for supplying,
By detecting the humidity of the generated gas and controlling the amount of water supplied by the second water supply unit according to the detected humidity, even if the operating state of the reforming system fluctuates, a shifter is provided. Since the moisture concentration of the generated gas that flows in can be stabilized, the shifter can always be operated under optimum conditions, and the excellent effect that the CO concentration of the gas treated by the shifter can always be stabilized is exhibited. It

In the first invention or the second invention, when the water supply amount is increased as the humidity of the produced gas becomes lower, the water concentration of the produced gas flowing into the shifter can be increased quickly. Because you can raise
The transient response of the reforming system is improved.

Further, according to the third aspect of the invention, a reformer for gasifying the raw fuel and then reforming it to produce a hydrogen-rich gas, and a reformer contained in the produced gas produced by the reformer A water supply control method in a reforming system comprising a shifter for removing carbon oxide by a shift reaction and a first water supply means for supplying water to the raw fuel, which is required for the reforming system. Calculate the rate of change in the amount of gas produced,
By controlling the amount of water supplied by the first water supply means in accordance with this rate of change, the water concentration of the product gas flowing into the shifter is stabilized even if the operating state of the reforming system changes. Therefore, it is possible to always operate the shifter under the optimum conditions, and it is possible to always stabilize the CO concentration of the gas treated by the shifter, which is an excellent effect.

Further, according to the fourth aspect of the invention, a reformer for gasifying the raw fuel and then reforming it to produce a hydrogen-rich gas, and a reformer included in the produced gas produced by the reformer In a water supply control method in a reforming system comprising a shifter for removing carbon oxide by a shift reaction and a first water supply means for supplying water to the raw fuel, water is supplied to the produced gas. A second water supply means for supplying,
The operating state of the reforming system is calculated by calculating the rate of change in the amount of generated gas required for the reforming system and controlling the amount of water supplied by the second water supply means according to the rate of change. Even if the value fluctuates, the water concentration of the product gas flowing into the shifter can be stabilized, so that the shifter can always be operated under optimum conditions, and the CO concentration of the gas treated by the shifter can always be stabilized. It has an excellent effect that it can be done.

In the third or fourth aspect of the invention, when the rate of change of the amount of generated gas is determined from the rate of change of the opening degree of the accelerator of the vehicle equipped with the reforming system, Since the reforming system quickly follows the transient state, the transient response of the reforming system is improved.

In the third invention or the fourth invention, when the increase in the water supply amount is controlled to increase as the change rate of the generated gas increases in the positive direction, the generation flowing into the shifter is increased. Since the water concentration of the gas can be raised quickly, the transient response of the reforming system is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a reforming system capable of implementing a water supply control method according to a first embodiment of this invention.

FIG. 2 is a diagram showing a relationship between a shift catalyst temperature and a shifter outlet CO concentration when a shifter inlet water content is 20%.

FIG. 3 is a graph showing the relationship between shift catalyst temperature and shifter outlet CO concentration when the shifter inlet water content is 30%.

FIG. 4 is a flow chart of water supply control in the first embodiment.

FIG. 5 is a humidity / S / C ratio map used in the water supply control of the first embodiment.

FIG. 6 is a graph showing the behavior of the water concentration of the shifter inlet gas when the output of the reformer system is increased.

FIG. 7 is a graph showing the behavior of CO concentration in the shifter outlet gas when the output of the reformer system is increased.

FIG. 8 is a water supply control pattern table.

FIG. 9 is a flowchart of water supply control in the water supply control method according to the second embodiment of the present invention.

FIG. 10 is a configuration diagram of a reforming system capable of implementing the water supply control method according to the third embodiment of the present invention.

FIG. 11 is a flow chart of water supply control in the third embodiment.

FIG. 12 is a sub-injector duty ratio map used in the water supply control of the third embodiment.

FIG. 13 is a sub-injector / injection time map used in the water supply control of the third embodiment.

FIG. 14 is a main injector / duty ratio reduction rate map used for the water supply control of the third embodiment.

FIG. 15 is a main injector / weight reduction time map used for the water supply control of the third embodiment.

FIG. 16 is a graph showing the relationship between catalyst temperature and equilibrium constant Kp.

[Explanation of symbols]

2 reformer 4 shifters 11 Water supply pipe, (first water supply means) 12 First control valve (first water supply means) 13 Main injector (first water supply means) 17 Water supply pipe (second water supply means) 18 Second control valve (second water supply means) 19 Sub-injector (second water supply means)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // H01M 8/10 H01M 8/10 (72) Inventor Takashi Arai 1-4-1, Chuo, Wako, Saitama No. F-term in Honda R & D Co., Ltd. (reference) 4G040 EA02 EA03 EA06 EB03 EB32 EB43 5H026 AA06 5H027 AA06 BA01 BA16 BA17 DD00 MM14

Claims (7)

[Claims] 1. A reformer that gasifies a raw fuel and then reforms it to produce a hydrogen-rich gas, and carbon monoxide contained in the produced gas produced by the reformer is removed by a shift reaction. A water supply control method in a reforming system comprising a shifter and a first water supply means for supplying water to the raw fuel, wherein the humidity of the produced gas is detected, and the humidity is detected according to the detected humidity. A water supply control method for a reforming system, comprising controlling the amount of water supplied by the first water supply means. 2. A reformer that gasifies raw fuel and then reforms it to produce a hydrogen-rich gas, and carbon monoxide contained in the produced gas produced by the reformer is removed by a shift reaction. A water supply control method in a reforming system comprising a shifter and a first water supply means for supplying water to the raw fuel, the second water supply means supplying water to the generated gas. And detecting the humidity of the produced gas, and controlling the amount of water supplied by the second water supply means according to the detected humidity. 3. The water supply control method for a reforming system according to claim 1, wherein the water supply amount is controlled to increase as the humidity of the produced gas decreases. 4. A reformer that gasifies a raw fuel and reforms it to produce a hydrogen-rich gas, and carbon monoxide contained in the produced gas produced by the reformer is removed by a shift reaction. A water supply control method in a reforming system comprising a shifter and a first water supply means for supplying water to the raw fuel, wherein a rate of change in the amount of generated gas required for the reforming system is calculated. Then, the water supply control method of the reforming system is characterized in that the water supply amount by the first water supply means is controlled according to the rate of change. 5. A reformer that gasifies a raw fuel and reforms it to produce a hydrogen-rich gas, and carbon monoxide contained in the produced gas produced by the reformer is removed by a shift reaction. A water supply control method in a reforming system comprising a shifter and a first water supply means for supplying water to the raw fuel, the second water supply means supplying water to the generated gas. Of the reforming system, the rate of change in the amount of generated gas required for the reforming system is calculated, and the amount of water supplied by the second water supply means is controlled according to the rate of change. Water supply control method. 6. The modification according to claim 4, wherein the rate of change of the generated gas amount is obtained from the rate of change of the opening degree of the accelerator of the vehicle on which the reforming system is mounted. Water supply control method for quality system. 7. The reforming system according to claim 4, wherein the reforming system is controlled so that the increase in the water supply amount increases as the rate of change in the generated gas amount increases in the positive direction. Water supply control method.