JP4013847B2 - Fuel reformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel reformer using premixed fuel.
[0002]
[Prior art]
In a fuel cell system, a fuel reformer is used to generate hydrogen gas from a hydrocarbon-based raw fuel. The fuel reformer includes a reforming unit, and the reforming unit reforms the raw fuel to generate hydrogen gas.
[0003]
The reformer usually generates hydrogen gas using a steam reforming reaction. In this case, water is supplied to the reforming unit together with the raw fuel. For example, in Patent Document 1, gasoline or a mixture of alcohol and water (premixed fuel) is stored in a tank, and the premixed fuel is supplied to the reforming unit.
[0004]
[Patent Document 1]
JP-A-11-79703
[0005]
[Problems to be solved by the invention]
By the way, the value of the ratio between the number of water molecules contained in the premixed fuel in the tank and the number of carbon atoms in the raw fuel (hereinafter also simply referred to as “S / C”) gradually increases with time. . This is because raw fuel is more easily vaporized than water. However, conventionally, the change in the S / C of the premixed fuel stored in the tank has not been considered. For this reason, the reforming reaction may not proceed well in the reforming section. That is, when the proportion of water contained in the premixed fuel increases, the temperature inside the reforming section decreases, and as a result, the reforming reaction does not proceed well.
[0006]
The present invention has been made to solve the above-described problem, and when the S / C of the premixed fuel increases, the operation of the reforming section is executed in a state where the reforming reaction does not proceed well. It is an object of the present invention to provide a technique capable of avoiding this.
[0007]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the problems described above, an apparatus of the present invention is a fuel reformer,
A reforming section for reforming a hydrocarbon-based raw fuel to generate hydrogen gas;
A premixed fuel tank for storing a premixed fuel in which the raw fuel and water are premixed, and a premixed fuel supply unit for supplying the premixed fuel to the reforming unit;
An estimation unit for estimating a value of a ratio between the number of water molecules contained in the premixed fuel in the premixed fuel tank and the number of carbon atoms in the raw fuel;
A control unit for controlling the operation of the fuel reformer, based on the estimated value obtained by the estimation unit;
It is characterized by providing.
[0008]
In this fuel reformer, the S / C of the premixed fuel stored in the premix fuel tank is estimated, and the operation of the fuel reformer is controlled based on the estimated value of S / C. For this reason, when the S / C of the premixed fuel is increased, it is possible to avoid the operation of the reforming unit being performed in a state where the reforming reaction does not proceed well.
[0009]
In the above apparatus,
An air supply unit for supplying air to the reforming unit;
It is preferable that the control unit controls the air supply unit based on the estimated value to adjust the amount of air supplied to the reforming unit.
[0010]
If air is supplied to the reforming section, the partial oxidation reforming reaction can proceed in the reforming section. The partial oxidation reforming reaction is an exothermic reaction. Therefore, when the S / C of the premixed fuel is a relatively large value, the amount of air supplied to the reforming unit is increased, thereby improving the S / C of the premixed fuel. It can suppress that the temperature inside a part falls, As a result, a reforming reaction can be advanced favorably.
[0011]
In the above apparatus,
When the estimated value is equal to or less than the first reference value, the control unit does not increase the amount of air supplied to the reforming unit in accordance with the estimated value, and the estimated value is the first value. If it is larger than the reference value, the amount of air supplied to the reforming unit may be increased according to the estimated value.
[0012]
In the above device,
The premixed fuel supply unit further includes:
A raw fuel tank for storing the raw fuel, the raw fuel supply unit for supplying the raw fuel to the premixed fuel tank,
The control unit may control the raw fuel supply unit based on the estimated value so as to supply the raw fuel to the premixed fuel tank.
[0013]
In this way, even when the S / C of the premixed fuel in the premixed fuel tank increases, the S / C of the premixed fuel can be reduced by supplying the raw fuel to the premixed fuel tank. As a result, the reforming reaction can proceed well.
[0014]
In the above apparatus,
When the estimated value is equal to or less than the second reference value, the control unit does not cause the raw fuel supply unit to supply the raw fuel to the premixed fuel tank, and the estimated value is the second reference value. When the value is larger than the value, the raw fuel supply unit may supply the raw fuel to the premixed fuel tank according to the estimated value.
[0015]
The second reference value may be set to a value larger than the first reference value, or may be set to a value equal to the first reference value. Specifically, when adopting a configuration in which the amount of air supplied to the reforming unit can be adjusted according to the estimated value of S / C, the second reference value is larger than the first reference value. It is preferably set. Further, in the case of adopting a configuration in which the amount of air supplied to the reforming unit cannot be adjusted according to the estimated value of S / C, the second reference value is set substantially equal to the first reference value. It is preferable.
[0016]
In the above apparatus,
A notification unit for executing notification to the user;
When the estimated value is larger than a third reference value, the control unit may cause the notification unit to notify the user that the estimated value is out of a predetermined range.
[0017]
In this way, the user can be alerted and the user can take some measures as necessary.
[0018]
The third reference value may be set to a value equal to the first reference value or the second reference value, or may be larger than the first reference value or the second reference value. It may be set to a value.
[0019]
In the above device,
The estimation unit includes
A specific gravity measuring unit for measuring the specific gravity of the premixed fuel in the premixed fuel tank;
The estimation unit may estimate the value of the ratio using the measured specific gravity.
[0020]
In the above apparatus,
The estimation unit includes
An impedance measuring unit for measuring the impedance of the premixed fuel in the premixed fuel tank;
The estimation unit may estimate the value of the ratio using the measured impedance.
[0021]
By doing so, it is possible to accurately estimate the S / C of the premixed fuel.
[0022]
In the above device,
The estimation unit includes
A replenishment amount measuring unit for measuring the replenishment amount of the premixed fuel to the premixed fuel tank;
An elapsed time measuring unit for measuring an elapsed time from when the premixed fuel is replenished in the premixed fuel tank;
With
The estimation unit may estimate the value of the ratio using the measured replenishment amount and the measured elapsed time.
[0023]
In this way, the S / C of the premixed fuel can be estimated with a relatively simple configuration.
[0024]
In the above apparatus,
The estimation unit further includes:
A first temperature measuring unit for measuring a first temperature related to the temperature inside the premixed fuel tank;
It is preferable that the estimation unit further estimates the value of the ratio using the measured first temperature.
[0025]
Thus, if the replenishment amount of the premixed fuel, the elapsed time since the premixed fuel was replenished, and the first temperature related to the temperature inside the premixed fuel tank, the premixed fuel It becomes possible to estimate S / C more accurately.
[0026]
In the above apparatus,
The estimation unit further includes:
A second temperature measuring unit for measuring a second temperature related to the temperature inside the reforming unit;
The estimation unit may further estimate the value of the ratio using the measured second temperature.
[0027]
Thus, if the second temperature related to the temperature inside the reforming unit is used, the S / C of the premixed fuel can be estimated more accurately.
[0028]
In the above device,
The estimation unit includes
A temperature measuring unit for measuring a temperature related to the temperature inside the reforming unit;
The estimation unit may estimate the value of the ratio using the measured temperature.
[0029]
Thus, if the temperature related to the temperature inside the reforming unit is used, the S / C of the premixed fuel can be accurately estimated.
[0030]
The present invention can be realized in various modes such as a fuel reforming apparatus, a fuel reforming method, a fuel cell system including the fuel reforming apparatus, and a device such as a moving body equipped with the fuel cell system. .
[0031]
DETAILED DESCRIPTION OF THE INVENTION
A. First embodiment:
Next, embodiments of the present invention will be described based on examples. FIG. 1 is an explanatory diagram showing a schematic configuration of the fuel cell system in the first embodiment. The fuel cell system is mounted on a vehicle.
[0032]
As shown in the figure, the fuel cell system includes a fuel cell 100, a fuel gas supply unit 200A, an oxidizing gas supply unit 300, and a control unit 600A for controlling the operation of the entire fuel cell system. As will be described later, the fuel gas supply unit 200A is a fuel reformer that reforms raw fuel to generate hydrogen gas, and supplies the fuel cell 100 with fuel gas containing hydrogen gas. The oxidizing gas supply unit 300 includes a blower 310 and supplies an oxidizing gas (air) containing oxygen gas to the fuel cell 100. The fuel cell 100 generates power using the fuel gas supplied from the fuel gas supply unit 200 </ b> A and the oxidizing gas supplied from the oxidizing gas supply unit 300.
[0033]
The fuel reformer (fuel gas supply unit) 200A includes a premixed fuel tank 210, a blower 220, a vaporizer 230, a reformer 240, a first heat exchange unit 250, a shift unit 260, hydrogen, A separation unit 270, a second heat exchange unit 280, and a purification unit 290 are provided.
[0034]
The premixed fuel tank 210 is a tank that stores a premixed fuel in which a hydrocarbon-based raw fuel and water are mixed in advance. If raw fuel and water are mixed in advance in this way, freezing of water that can occur when water is stored individually can be avoided. The premixed fuel in the tank 210 is supplied to the vaporizer 230 via the pump 212 and the injection valve 214.
[0035]
In this embodiment, an emulsion in which gasoline as raw fuel and water are mixed using an emulsifier (surfactant) is used as the premixed fuel. As the emulsifier, for example, polyoxyethylene alkylene alkyl ether, a derivative thereof, polyoxyethylene lauryl ether, or the like can be used. As an emulsifier, what is comprised by the carbon atom, the hydrogen atom, and the oxygen atom is preferable. By so doing, poisoning of the reforming catalyst provided in the reforming unit 240 can be prevented.
[0036]
The blower 220 supplies air to the vaporization unit 230 via the first heat exchange unit 250. Note that the air is heated by passing through the heat exchanging unit 250.
[0037]
The vaporization unit 230 includes a heating unit 232 and vaporizes the premixed fuel injected by the injection valve 214. In the vaporization unit 230, a mixed gas of raw fuel, water vapor, and air is generated, and the mixed gas is supplied to the reforming unit 240. Note that the temperature inside the vaporization unit 230 is increased by heat given from the heating unit 232, heat transmitted from the reforming unit 240, heat of air heated through the heat exchange unit 250, or the like. However, heating by the heating unit 232 is normally performed when the reforming unit 240 starts operation, and is not performed during a period in which the reforming unit 240 performs steady operation. When the premixed fuel is injected into the high temperature vaporizer 230, the premixed fuel is immediately vaporized.
[0038]
The reforming unit 240 includes a reforming catalyst that promotes the reforming reaction. The raw fuel contained in the mixed gas is converted into hydrogen gas and carbon monoxide gas using water vapor and oxygen gas in the air. The reformed gas is reformed. That is, in the reforming unit 240, a combined reforming reaction that combines a steam reforming reaction using steam and a partial oxidation reforming reaction using oxygen gas proceeds. The steam reforming reaction is an endothermic reaction, and the partial oxidation reforming reaction is an exothermic reaction. The heat generated by the partial oxidation reforming reaction is used for the steam reforming reaction.
[0039]
The first heat exchange unit 250 cools the reformed gas supplied from the reforming unit 240 and supplies it to the shift unit 260. As described above, the heat of the reformed gas is given to the air supplied from the blower 220 to the vaporizer 230. The reason why the reformed gas is cooled in the heat exchanging unit 250 is that the reaction temperature in the shift unit 260 is lower than the reaction temperature in the reforming unit 240.
[0040]
The shift unit 260 includes a shift catalyst that promotes the shift reaction, and converts the carbon monoxide gas in the reformed gas into hydrogen gas and carbon dioxide gas using water vapor. The reformed gas having a reduced carbon monoxide gas concentration is supplied to the hydrogen separator 270. In addition, by reducing the carbon monoxide gas concentration in the shift unit 260, poisoning of the noble metal catalyst supported on the electrode inside the fuel cell 100 can be suppressed.
[0041]
The hydrogen separation unit 270 includes a supply chamber 272, a hydrogen permeable membrane 270f, and an extraction chamber 274. The reforming gas is supplied from the shift unit 260 to the supply chamber 272, and the oxidizing off gas is supplied from the fuel cell 100 to the extraction chamber 274. The hydrogen permeable membrane 270f separates the hydrogen gas by selectively allowing the hydrogen gas in the reformed gas supplied to the supply chamber 272 to permeate. The oxidizing off gas supplied to the extraction chamber 274 functions as a carrier gas that carries the hydrogen gas that has permeated the hydrogen permeable membrane 270f, and promotes the permeation of the hydrogen gas. The extracted hydrogen gas is cooled by the second heat exchange unit 280 and then supplied to the fuel cell 100.
[0042]
Note that oxygen gas remains in the oxidizing off gas. For this reason, when the oxidizing off gas is supplied to the extraction chamber 274, the oxygen gas reacts with the hydrogen gas that has passed through the hydrogen permeable membrane 270f. Specifically, palladium constituting the hydrogen permeable membrane 270f acts as a catalyst, and a combustion reaction occurs on the hydrogen permeable membrane. However, the amount of hydrogen gas consumed by this combustion reaction is small. For this reason, in this embodiment, the oxidizing off gas is used as the carrier gas.
[0043]
The purification unit 290 oxidizes the carbon monoxide gas discharged without being converted in the shift unit 260 using oxygen gas in the air. The purified gas is discharged to the atmosphere.
[0044]
The controller 600A controls each part of the fuel cell system. In particular, the controller 600A controls the operation of the fuel reformer 200A to adjust the amount of premixed fuel and the amount of air supplied to the vaporizer 230 based on the amount of hydrogen gas to be supplied to the fuel cell 100. To do.
[0045]
By the way, the S / C of the premixed fuel stored in the premixed fuel tank 210 may increase with time. This is because raw fuel is more easily vaporized than water. Therefore, if the premixed fuel is supplied to the reforming unit 240 on the assumption that the S / C of the premixed fuel is maintained substantially constant, the reforming reaction may not proceed well. Specifically, when the S / C of the premixed fuel increases, water is supplied to the vaporization unit 230 at a higher rate. At this time, the vaporization unit 230 uses more heat to vaporize water, and as a result, the temperature of the mixed gas decreases. Then, when a mixed gas having a relatively low temperature is supplied to the reforming unit 240, the temperature inside the reforming unit 240 (more specifically, the temperature of the reforming catalyst) decreases, and as a result, the reforming reaction is performed. May or may not progress.
[0046]
Therefore, in the present embodiment, the control unit 600A controls the operation of the fuel reformer 200A based on the estimated value of S / C of the premixed fuel stored in the premixed fuel tank 210.
[0047]
Specifically, in the fuel cell system of the present embodiment, an impedance meter 610 for measuring the impedance of the premixed fuel is provided. Control unit 600A estimates the S / C of the premixed fuel using the measured value of impedance meter 610. Then, control unit 600A controls the operation of blower 220 based on the estimated value of S / C. Since the impedance of the premixed fuel changes according to the S / C of the premixed fuel, the S / C of the premixed fuel can be accurately estimated by using the measured value of the impedance meter 610.
[0048]
In addition, in the fuel cell system of the present embodiment, a notification unit 700 for executing notification to the user is provided. Based on the estimated value of S / C, control unit 600A causes notification unit 700 to execute notification to the user. Note that the notification by the notification unit 700 may be performed by a display device included in the notification unit, or may be performed by a speaker included in the notification unit.
[0049]
The premixed fuel tank 210, the pump 212, the injection valve 214, and the vaporization unit 230 shown in FIG. 1 correspond to the premixed fuel supply unit in the present invention, and the blower 220 and the vaporization unit 230 correspond to the air supply unit. . The impedance meter 610 and the control unit 600A correspond to the estimation unit in the present invention.
[0050]
FIG. 2 is a flowchart showing the contents of processing using the S / C of the premixed fuel in the first embodiment. This process is executed in accordance with an instruction from control unit 600A.
[0051]
In step S102, the S / C of the premixed fuel in the premixed fuel tank 210 is estimated. Specifically, control unit 600A acquires the measured value of impedance meter 610, and estimates the S / C of the premixed fuel using the measured value.
[0052]
In step S104, it is determined whether or not the estimated value of S / C is equal to or less than a first threshold value VH. The first threshold value VH is an upper limit value that allows the reforming reaction to proceed well, and is set to about 3 to about 4, for example. That is, when the estimated value of S / C is equal to or less than the first threshold value VH, it is determined that the reforming reaction can be favorably progressed, and the process proceeds to step S110. On the other hand, when the estimated value of S / C is larger than the first threshold value VH, it is determined that it is difficult to make the reforming reaction proceed well, and the process proceeds to step S106.
[0053]
In step S106, the user is notified that it is difficult to make the reforming reaction proceed well. By this notification or warning, the user can know that the ratio of the raw fuel in the premixed fuel is considerably reduced, and can take some measures such as replenishing the premixed fuel. In this embodiment, when it is difficult to make the reforming reaction proceed well, the operation of the reforming unit is not started.
[0054]
In step S110, an operation start process of the reforming unit 240 is executed. Specifically, control unit 600 </ b> A starts heating by heating unit 232 or starts supplying premixed fuel and air to vaporizing unit 230.
[0055]
When the operation of the reforming unit 240 is started, in step S112, the S / C of the premixed fuel in the premixed fuel tank 210 is estimated as in step S102. Specifically, control unit 600A obtains the measured value of impedance meter 610 again, and estimates S / C of the premixed fuel again using the measured value.
[0056]
In step S114, it is determined whether or not the estimated value of S / C is less than or equal to the second threshold VL. The second threshold value VL allows the reforming reaction to proceed satisfactorily without performing special processing, more specifically, without increasing the amount of air supplied from the blower 220 to the reforming unit 240. The upper limit is possible, and is set to about 2, for example. That is, when the estimated value of S / C is equal to or less than the second threshold value VL, it is determined that there is no need to increase the air amount in order to allow the reforming reaction to proceed well, and the process proceeds to step S116a. On the other hand, when the estimated value of S / C is larger than the second threshold value VL, it is determined that it is necessary to increase the air amount in order to allow the reforming reaction to proceed well, and the process proceeds to step S116b.
[0057]
As can be seen from the above description, the state in which the S / C of the premixed fuel is larger than the first threshold value VH can be improved even if the amount of air supplied from the blower 220 to the reforming unit 240 is increased. This means that it is difficult to make the reaction proceed well.
[0058]
In step S116a, the reforming unit 240 is operated in the normal mode. Specifically, the control unit 600A determines the amount of premixed fuel and the amount of air supplied to the reforming unit 240 according to the required load, in other words, according to the amount of current that the fuel cell should output. Adjust.
[0059]
On the other hand, in step S116b, the reforming unit 240 is operated in the air amount increase mode. Specifically, the control unit 600A controls the blower 220 to increase the amount of air supplied to the reforming unit 240 as compared with the case where the reforming unit 240 is operated in the normal mode. The increment of the air amount is determined according to the estimated value of S / C. As the amount of air increases, the proportion of raw fuel consumed by the partial oxidation reforming reaction (exothermic reaction) increases in the reforming unit 240. For this reason, it is possible to suppress a decrease in the temperature inside the reforming unit 240 (more specifically, the temperature of the reforming catalyst) due to an increase in the S / C of the premixed fuel in the tank 210. it can. As a result, even when S / C is a relatively large value (that is, when S / C is equal to or smaller than the first threshold value VH and greater than the second threshold value VL), the reformer 240 has an internal structure. The temperature can be maintained within a predetermined temperature range, and the reforming reaction can proceed favorably.
[0060]
In step S118, it is determined whether or not to end the operation of the reforming unit 240. Specifically, in step S118, it is determined whether or not an instruction to end operation of the reforming unit 240 is given from the user. When the operation of the reforming unit 240 is continued, the processes of steps S112, S114, S116a, S116b, and S118 are repeatedly executed. On the other hand, when the operation of the reforming unit 240 is ended, the process proceeds to step S120.
[0061]
In step S120, an operation end process of the reforming unit 240 is executed. Specifically, control unit 600A stops the supply of premixed fuel and air to vaporization unit 230.
[0062]
As described above, in the fuel reforming apparatus 200A of the present embodiment, the S / C of the premixed fuel stored in the premixed fuel tank 210 is estimated, and the reforming is performed based on the estimated value of S / C. Processing for increasing the amount of air supplied to the unit and processing for notifying the user are executed. Specifically, when the estimated value of S / C is equal to or less than the second threshold value VL (corresponding to the first reference value of the present invention), the amount of air supplied to the reforming unit is used as the estimated value. If the estimated value of S / C is larger than the second threshold value VL, the amount of air supplied to the reforming unit is increased according to the estimated value. When the estimated value of S / C is larger than the first threshold value VH (corresponding to the third reference value of the present invention), the notification unit is notified to the user. By adopting this configuration, when the S / C of the premixed fuel is increased, it is possible to avoid the operation of the reforming unit being performed in a state where the reforming reaction does not proceed well.
[0063]
A1. Modification of the first embodiment:
FIG. 3 is an explanatory diagram showing an outline of a fuel cell system according to a modification of the first embodiment. The fuel reformer 200A1 of FIG. 3 is substantially the same as FIG. 1, but includes a hydrometer 620 for measuring the specific gravity of the premixed fuel instead of the impedance meter 610. Control unit 600A1 estimates the S / C of the premixed fuel using the measured value of hydrometer 620. Since the specific gravity of the premixed fuel changes according to the S / C of the premixed fuel, the S / C of the premixed fuel can be accurately estimated even when the measured value of the hydrometer 620 is used. Note that the control unit 600A performs the same processing as in FIG. 2 based on the estimated value of S / C.
[0064]
B. Second embodiment:
FIG. 4 is an explanatory diagram showing an outline of the fuel cell system in the second embodiment. The fuel reformer 200B of FIG. 4 is substantially the same as that of FIG. 1, but a liquid level gauge 630 for measuring the liquid level position of the premixed fuel in the premixed fuel tank 210, instead of the impedance meter 610, And a timer 640 for measuring an elapsed time from when the premixed fuel is replenished.
[0065]
Control unit 600B estimates the S / C of the premixed fuel using the measurement value of liquid level gauge 630 and the measurement value of timer 640. Specifically, control unit 600B obtains the measured value of liquid level meter 630 immediately after the replenishment of premixed fuel is completed, and obtains the replenishment amount of premixed fuel in advance. However, here, it is assumed that the premixed fuel does not remain in the tank 210 immediately before the premixed fuel is replenished. Since the S / C of the premixed fuel to be replenished is a substantially constant value, the S / C immediately after the premixed fuel is replenished is known. That is, assuming that the number of water molecules and the number of carbon atoms in the premixed fuel supplied to the tank 210 are A and B, respectively, the initial value of S / C of the premixed fuel is A / B. Here, when the number of water molecules and the number of carbon atoms that decrease in a predetermined time (for example, 1 hour) are α and β, respectively, when a predetermined time (for example, 1 hour) has elapsed since the premixed fuel was supplied to the tank 210. The S / C of the premixed fuel is estimated as (A−α) / (B−β). Furthermore, when a predetermined time (for example, 1 hour) elapses, the S / C of the premixed fuel is estimated as (A-2α) / (B-2β).
[0066]
As described above, the control unit 600B estimates the S / C of the premixed fuel using the replenishment amount of the premixed fuel and the elapsed time after the replenishment. Note that the control unit 600B performs the same processing as in FIG. 2 based on the estimated value of S / C.
[0067]
The premix fuel tank is usually provided with a liquid level gauge for the user to check the remaining amount of premix fuel. Therefore, if the configuration of FIG. 4 is adopted, there is an advantage that the replenishment amount of the premixed fuel can be estimated with a relatively simple configuration.
[0068]
By the way, when the premixed fuel is replenished, a relatively small amount of premixed fuel usually remains in the tank 210. Therefore, in practice, the amount of premixed fuel remaining and S / C and the amount of premixed fuel to be replenished and S / C are used to determine the S of the premixed fuel in the tank 210 immediately after replenishment. / C is required. The residual amount of the premixed fuel can be obtained from the measured value of the liquid level gauge 630 immediately before the premixed fuel is replenished, and the replenishment amount of the premixed fuel is the just before and immediately after the premixed fuel is replenished. It can obtain | require from the difference of the measured value of the liquid level meter 630. Further, as the S / C of the remaining premixed fuel, an estimated value of S / C immediately before the premixed fuel is supplied can be used.
[0069]
In general, the S / C of the premixed fuel may be estimated using the replenishment amount of the premixed fuel and the elapsed time after replenishment.
[0070]
B1. Modification of the second embodiment:
FIG. 5 is an explanatory diagram showing an outline of a fuel cell system in a modification of the second embodiment. The fuel reformer 200B1 in FIG. 5 is substantially the same as that in FIG. 4, but a thermometer 650 is added. The thermometer 650 is disposed in the vicinity of the premixed fuel tank 210.
[0071]
Similar to FIG. 4, control unit 600B1 estimates the S / C of the premixed fuel using the replenishment amount of the premixed fuel and the elapsed time after the replenishment. However, in this example, the control unit 600B1 further estimates the S / C of the premixed fuel using the measurement value of the thermometer 650. Thus, the reason for using the measurement value of the thermometer 650 is that the number of water molecules and the number of carbon atoms that decrease in a predetermined time (for example, 1 hour) actually depend on the temperature inside the premixed fuel tank 210. Because. That is, if the number of water molecules and the number of carbon atoms that decrease during a predetermined time (for example, 1 hour) are α (T) and β (T) that change according to the temperature T, the premixed fuel is supplied to the tank 210. When a predetermined time (for example, 1 hour) has elapsed, the S / C of the premixed fuel is estimated as (A−α (T1)) / (B−β (T1)). Further, when a predetermined time (for example, 1 hour) elapses, the S / C of the premixed fuel becomes (A−α (T1) −α (T2)) / (B−β (T1) −β (T2)). It is estimated to be.
[0072]
As described above, the control unit 600B1 estimates the S / C of the premixed fuel using the replenishment amount of the premixed fuel, the elapsed time after the replenishment, and the temperature near the premixed fuel tank 210. . Note that the control unit 600B1 executes the same process as in FIG. 2 based on the estimated value of S / C.
[0073]
In this example, the control unit 600B1 uses the α (T) and β (T) that change according to the temperature as the number of water molecules and the number of carbon atoms that decrease in a predetermined time, and calculates the S / C of the premixed fuel. Estimated. However, instead of this, the S / C of the premixed fuel is estimated by using α and β that do not depend on temperature as the number of water molecules and the number of carbon atoms that decrease in a predetermined time as in FIG. May be corrected according to the temperature.
[0074]
In this example, the thermometer 650 measures the temperature in the vicinity of the premixed fuel tank 210. Alternatively, the thermometer 650 may measure the outside air temperature (atmospheric temperature). The temperature inside the mixed fuel tank 210 may be measured.
[0075]
In general, the S / C of the premixed fuel may be estimated using the replenishment amount of the premixed fuel, the elapsed time after the replenishment, and the temperature related to the temperature inside the premixed fuel tank. Thus, if the temperature related to the temperature inside the premixed fuel tank is used, the S / C of the premixed fuel can be estimated more accurately.
[0076]
C. Third embodiment:
FIG. 6 is an explanatory diagram showing an outline of the fuel cell system in the third embodiment. The fuel reformer 200C of FIG. 6 is substantially the same as FIG. 5, except that a thermometer 680 for measuring the temperature inside the reforming unit 240, more specifically, the temperature of the reforming catalyst, is added. Yes.
[0077]
FIG. 7 is a flowchart showing the contents of processing using the S / C of the premixed fuel in the third embodiment. FIG. 7 is substantially the same as FIG. 2, but the content of step S112B is changed. Steps S113B and S119B are added.
[0078]
In step S112B, as in step S102, the S / C of the premixed fuel in the premixed fuel tank 210 is estimated. Specifically, the control unit 600C uses the premixed fuel replenishment amount obtained in advance, the elapsed time after replenishment, and the temperature in the vicinity of the premixed fuel tank 210 to determine the S of the premixed fuel. / C is estimated. However, in step S112B, control unit 600C further corrects the estimated S / C value of the premixed fuel using the temperature inside reforming unit 240 given from thermometer 680. This is because there is a possibility that the estimated value obtained using the replenishment amount of the premixed fuel, the elapsed time after the replenishment, and the temperature in the vicinity of the premixed fuel tank 210 is incorrect. That is, when the estimated value of S / C is within a normal range (for example, about 1.5 to about 2) that does not require an increase in the air amount, the temperature inside the reforming unit 240 is low. The actual S / C is considered to be higher than the estimated value. For this reason, in the present embodiment, the controller 600C corrects the estimated value of S / C using the temperature inside the reforming unit 240 after the operation of the reforming unit 240 is started.
[0079]
In step S113B, it is determined whether the corrected estimated value of S / C is less than or equal to the first threshold value VH. If the corrected estimated value of S / C is larger than the first threshold value VH, in other words, if it is determined that it is difficult to make the reforming reaction proceed well, step S119B Proceed to In step S119B, notification to the user is performed as in step S106. This notification can prompt the user to take some measures such as replenishing the premixed fuel. Thereafter, in step S120, an operation end process of the reforming unit 240 is executed.
[0080]
When the reforming unit 240 is operated in the air amount increasing mode, the ratio of the raw fuel consumed in the partial oxidation reforming reaction (exothermic reaction) is increased, and the temperature inside the reforming unit 240 is increased. Will rise. Accordingly, in this case, the estimated value of S / C may be corrected in consideration of the amount of air supplied to the reforming unit 240.
[0081]
If the temperature inside the reforming unit 240 is used as in the present embodiment, the actual reforming reaction inside the reforming unit 240 can be taken into account, so that the S / C of the premixed fuel can be estimated more accurately. There is an advantage that you can.
[0082]
In the present embodiment, the thermometer 680 measures the temperature inside the reforming unit 240, but instead, measures the temperature of the reformed gas discharged from the reforming unit 240. Also good. In general, the thermometer may measure a temperature related to the temperature inside the reforming section (more specifically, the temperature of the reforming catalyst).
[0083]
Further, in the present embodiment, the fuel reformer 200C includes a liquid level gauge 630, a timer 640, and a thermometer 650 provided in the vicinity of the premixed fuel tank 210, as in FIG. Can be omitted. In this case, the S / C of the premixed fuel may be estimated using only the thermometer 680 for measuring the temperature inside the reforming unit 240. However, if the configuration of this embodiment is adopted, there is an advantage that the S / C of the premixed fuel can be estimated before the reforming unit 240 starts operation.
[0084]
D. Fourth embodiment:
FIG. 8 is an explanatory diagram showing an outline of the fuel cell system in the fourth embodiment. The fuel reformer 200D of FIG. 8 is substantially the same as that of FIG. 1, but the raw fuel tank 216 and the pump 218 are added, and the notification unit 700 is omitted. In accordance with this change, a stirrer 211 is provided inside the premixed fuel tank 210D. The raw fuel tank 216 stores raw fuel that is not mixed with water.
[0085]
The raw fuel tank 216 and the pump 218 shown in FIG. 8 correspond to the raw fuel supply unit in the present invention.
[0086]
FIG. 9 is a flowchart showing the contents of processing using the S / C of the premixed fuel in the fourth embodiment. FIG. 9 is substantially the same as FIG. 2, but step S108D is executed instead of step S106.
[0087]
In step S108D, when it is determined in step S104 that the estimated value of S / C is larger than the first threshold value VH, in other words, it is difficult to make the reforming reaction proceed well. If it is determined, it is executed. In step S108D, the control unit 600D controls the pump 218 to supply the raw fuel stored in the raw fuel tank 216 into the premixed fuel tank 210D. At this time, the controller 600D operates the agitator 211 to mix the premixed fuel remaining in the premixed fuel tank 210D and the raw fuel supplied in the tank 210D. By replenishing the raw fuel in this manner, the S / C of the premixed fuel in the premixed fuel tank 210D can be increased. In the present embodiment, the supply amount of the raw fuel is determined according to the estimated value of S / C so that the S / C after the supply of the raw fuel is equal to or less than the second threshold value VL. When step S108D ends, steps S102 and S104 are executed again.
[0088]
As described above, in the fuel reforming apparatus 200D of the present embodiment, the raw fuel supply process and the process for increasing the amount of air supplied to the reforming unit are executed based on the estimated value of S / C. . Specifically, when the estimated value of S / C is equal to or lower than the first threshold value VH (corresponding to the second reference value of the present invention), the raw fuel is supplied to the raw fuel supply unit to the premixed fuel tank. When the estimated value of S / C is larger than the first threshold value VH without being supplied, the raw fuel is supplied to the premixed fuel tank by the raw fuel supply unit according to the estimated value. Further, when the estimated value of S / C is equal to or less than the second threshold value VL (corresponding to the first reference value of the present invention), the amount of air supplied to the reforming unit is increased according to the estimated value. If the estimated value is larger than the second threshold value VL, the amount of air supplied to the reforming unit is increased according to the estimated value. By adopting the configuration of this embodiment, even when the S / C of the premixed fuel increases in the premixed fuel tank, the S / C of the premixed fuel is supplied by supplying the raw fuel to the premixed fuel tank. Therefore, the reforming reaction can proceed well.
[0089]
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0090]
(1) In the above embodiment, the S / C of the premixed fuel stored in the premixed fuel tank is estimated using various methods. Specifically, in FIGS. 1 and 8, S / C is estimated using the impedance of the premixed fuel, and in FIG. 3, S / C is estimated using the specific gravity of the premixed fuel. Yes. In FIG. 4, S / C is estimated using the replenishment amount of the premixed fuel and the elapsed time after replenishment. In FIG. 5, S / C is the replenishment amount of the premixed fuel and the elapsed time after replenishment. Over time, it is estimated using a temperature related to the temperature inside the premixed fuel tank. In FIG. 6, the S / C is estimated using the temperature related to the temperature inside the reforming section together with the temperature related to the replenishment amount of the premixed fuel, the elapsed time after replenishment, the temperature inside the premixed fuel tank. ing. Further, as described with reference to FIG. 6, S / C can be estimated using only the temperature related to the temperature inside the reforming unit.
[0091]
Further, the S / C of the premixed fuel can be estimated using other methods. For example, it may be estimated using only the temperature related to the temperature inside the premixed fuel tank and the elapsed time after replenishment. Further, the S / C of the premixed fuel may be comprehensively estimated by arbitrarily combining the various methods as described above.
[0092]
Generally, the estimation unit only needs to be able to estimate the value of the ratio between the number of water molecules contained in the premixed fuel in the premixed fuel tank and the number of carbon atoms in the raw fuel.
[0093]
(2) In the first to third embodiments (FIGS. 2 and 7), in the first case where the estimated value of S / C is larger than the first threshold value VH, notification to the user is executed. However, instead of or together with this, the raw fuel in the raw fuel tank may be supplied into the premixed fuel tank in the same manner as in the fourth embodiment (FIG. 9). In this way, even when the estimated value of S / C is larger than the first threshold value VH, the reforming reaction can be favorably progressed in the reforming unit.
[0094]
In the first to fourth embodiments (FIGS. 2, 7, and 9), the second estimated value of S / C is equal to or smaller than the first threshold value VH and is larger than the second threshold value VL. In this case, the amount of air supplied to the reforming unit is increased according to the estimated value, but instead of this, or together with this, the raw fuel in the raw fuel tank is premixed according to the estimated value. You may make it supply in a fuel tank. In the second case, the user may be further notified.
[0095]
As described above, the notification to the user may be executed in the first case where the estimated value of S / C is larger than the first threshold value VH, or the estimated value of S / C is the second value. It may be executed in the second case that is larger than the threshold value VL. If notification to the user is executed in the second case, the user can be made aware that the estimated value of S / C has become a relatively large value. That is, the notification to the user may be executed in order to make the user recognize that the estimated value of S / C is out of a predetermined range (for example, about 1.5 to about 2). In this way, the user can be alerted and the user can take some measures as necessary.
[0096]
Further, in the first to fourth embodiments (FIGS. 2, 7, and 9), in the third case where the estimated value of S / C is equal to or less than the second threshold value VL, it is supplied to the reforming unit. The amount of air is maintained at a normal amount. However, instead of this, the amount of air supplied to the reforming unit may be increased according to the estimated value, or the raw fuel in the raw fuel tank may be increased into the premixed fuel tank according to the estimated value. You may make it supply. Alternatively, both the air amount increase process and the raw fuel supply process may be executed according to the estimated value.
[0097]
Further, in the above embodiment, an air amount increasing process, a raw fuel supplying process, a user notifying process, and the like are executed based on the estimated S / C value. Processing may be executed. For example, the reforming unit may include a heating unit. In this case, the control unit may adjust the heating amount by controlling the heating unit based on the estimated value of S / C. Even in this case, the temperature inside the reforming section (more specifically, the temperature of the reforming catalyst) can be suppressed from decreasing, and as a result, the reforming reaction can proceed well. .
[0098]
In general, the control unit may control the operation of the fuel reformer based on the estimated value obtained by the estimation unit.
[0099]
(3) In the above embodiment, the fuel reformer includes the vaporization unit, but the vaporization unit can be omitted. In this case, the reforming unit may include a heating unit for generating the amount of heat necessary for vaporizing the premixed fuel.
[0100]
In the above-described embodiment, the reforming unit advances the combined reforming reaction, which is a combination of the steam reforming reaction using steam and the partial oxidation reforming reaction using oxygen gas. However, instead of this, the raw fuel may be reformed by proceeding only with the steam reforming reaction. In this case, the reforming part should just be provided with the heating part. And a heating part should just generate | occur | produce the calorie | heat amount required for progress of steam reforming reaction (endothermic reaction).
[0101]
In the above embodiment, gasoline is used as the raw fuel, but alcohol, ether, aldehyde, or the like may be used instead. In the above embodiment, since gasoline is used as the raw fuel, an emulsifier is used. However, when the raw fuel and water are easily mixed, the emulsifier is unnecessary.
[0102]
In general, the reforming unit may generate hydrogen gas by reforming a hydrocarbon-based raw fuel. The premixed fuel supply unit may include a premixed fuel tank for storing a premixed fuel in which liquid raw fuel and water are mixed in advance, and supply the premixed fuel to the reforming unit.
[0103]
(4) In the above embodiment, the case where the fuel cell system including the fuel reformer is applied to a moving body (vehicle) has been described. However, the fuel cell system may be applied to a stationary power generation system.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell system according to a first embodiment.
FIG. 2 is a flowchart showing the contents of processing using S / C of premixed fuel in the first embodiment.
FIG. 3 is an explanatory diagram showing an outline of a fuel cell system in a modification of the first embodiment.
FIG. 4 is an explanatory diagram showing an outline of a fuel cell system in a second embodiment.
FIG. 5 is an explanatory diagram showing an outline of a fuel cell system in a modification of the second embodiment.
FIG. 6 is an explanatory diagram showing an outline of a fuel cell system according to a third embodiment.
FIG. 7 is a flowchart showing the contents of processing using S / C of premixed fuel in the third embodiment.
FIG. 8 is an explanatory diagram showing an outline of a fuel cell system according to a fourth embodiment.
FIG. 9 is a flowchart showing the contents of processing using S / C of premixed fuel in the fourth embodiment.
[Explanation of symbols]
100: Fuel cell
200A, A1, B, B1, C, D ... Fuel reformer (fuel gas supply unit)
210, 210D ... Premixed fuel tank
211 ... Agitator
212 ... Pump
214 ... Injection valve
216 ... Raw fuel tank
218 ... Pump
220 ... Blower
230 ... Vaporizer
232 ... heating unit
240 ... reforming section
250 ... Heat exchange section
260 ... shift section
270 ... Hydrogen separator
270f ... hydrogen permeable membrane
272 ... Supply room
274 ... Extraction chamber
280 ... Heat exchange section
290 ... Purification section
300 ... oxidizing gas supply section
310 ... Blower
600A, A1, B, B1, C, D ... control unit
610: Impedance meter
620 ... Hydrometer
630 ... Liquid level gauge
640 ... Timer
650 ... Thermometer
680 ... Thermometer
700 ... notification section

Claims (12)

A fuel reformer,
A reforming section for reforming a hydrocarbon-based raw fuel to generate hydrogen gas ;
An air supply unit for supplying air to the reforming unit;
Before comprise premixed fuel tank for the Kihara fuel and water to store pre-mixed premixed fuel, premixed fuel supply unit for supplying the premixed fuel to the reforming section,
An estimation unit for estimating a value of a ratio between the number of water molecules contained in the premixed fuel in the premixed fuel tank and the number of carbon atoms in the raw fuel;
A control unit for controlling the operation of the fuel reformer, based on the estimated value obtained by the estimation unit;
Bei to give a,
The control unit controls the air supply unit based on the estimated value to adjust the amount of air supplied to the reforming unit. The fuel reformer according to claim 1 , wherein
When the estimated value is equal to or less than the first reference value, the control unit does not increase the amount of air supplied to the reforming unit in accordance with the estimated value, and the estimated value is the first value. A fuel reformer that increases the amount of air supplied to the reforming unit according to the estimated value when larger than a reference value. The fuel reformer according to claim 1 or 2 ,
The estimation unit includes
A specific gravity measuring unit for measuring the specific gravity of the premixed fuel in the premixed fuel tank;
The estimation unit estimates a value of the ratio using the measured specific gravity. The fuel reformer according to claim 1 or 2 ,
The estimation unit includes
An impedance measuring unit for measuring the impedance of the premixed fuel in the premixed fuel tank;
The estimation unit is a fuel reformer that estimates the value of the ratio using the measured impedance. The fuel reformer according to claim 1 or 2 ,
The estimation unit includes
A temperature measuring unit for measuring a temperature related to the temperature inside the reforming unit;
The estimation unit is a fuel reformer that estimates the value of the ratio using the measured temperature. The fuel reformer according to claim 1 or 2 ,
The estimation unit includes
A replenishment amount measuring unit for measuring the replenishment amount of the premixed fuel to the premixed fuel tank;
An elapsed time measuring unit for measuring an elapsed time from when the premixed fuel is replenished in the premixed fuel tank;
With
The estimation unit is a fuel reformer that estimates the value of the ratio using the measured supply amount and the measured elapsed time. A fuel reformer,
A reforming section for reforming a hydrocarbon-based raw fuel to generate hydrogen gas;
A premixed fuel tank for storing a premixed fuel in which the raw fuel and water are premixed, and a premixed fuel supply unit for supplying the premixed fuel to the reforming unit;
An estimation unit for estimating a value of a ratio between the number of water molecules contained in the premixed fuel in the premixed fuel tank and the number of carbon atoms in the raw fuel;
A control unit for controlling the operation of the fuel reformer, based on the estimated value obtained by the estimation unit;
Bei to give a,
The estimation unit includes
A replenishment amount measuring unit for measuring the replenishment amount of the premixed fuel to the premixed fuel tank;
An elapsed time measuring unit for measuring an elapsed time from when the premixed fuel is replenished in the premixed fuel tank;
With
The estimation unit estimates the value of the ratio using the measured replenishment amount and the measured elapsed time . The fuel reformer according to claim 6 or 7 , wherein
The estimation unit further includes:
A first temperature measuring unit for measuring a first temperature related to the temperature inside the premixed fuel tank;
The estimation unit further estimates the value of the ratio using the measured first temperature.
Fuel reformer. The fuel reformer according to any one of claims 6 to 8 ,
The estimation unit further includes:
A second temperature measuring unit for measuring a second temperature related to the temperature inside the reforming unit;
The estimation unit further estimates the value of the ratio using the measured second temperature.
Fuel reformer. The fuel reformer according to any one of claims 1 to 9 ,
The premixed fuel supply unit further includes:
A raw fuel tank for storing the raw fuel, the raw fuel supply unit for supplying the raw fuel to the premixed fuel tank,
The control unit controls the raw fuel supply unit based on the estimated value, and supplies the raw fuel to the premixed fuel tank. The fuel reformer according to claim 10 , wherein
When the estimated value is equal to or less than a second reference value, the control unit does not cause the raw fuel supply unit to supply the raw fuel to the premixed fuel tank, and the estimated value is the second reference value. A fuel reformer that causes the raw fuel supply unit to supply the raw fuel to the premixed fuel tank according to the estimated value when the value is larger than the value. The fuel reformer according to any one of claims 1 to 11 , further comprising:
A notification unit for executing notification to the user;
The control unit causes the notification unit to notify the user that the estimated value is out of a predetermined range when the estimated value is larger than a third reference value.

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