JP2003068338A - Controller of fuel reforming system for moving body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for a reforming system to suppress the phase difference between the fuel input and output of an evaporator. SOLUTION: The reforming system for a moving body comprises: a fuel reformer 103 which forms a reformed gas composed mainly of hydrogen from water vapor, vapor of gaseous fuel or liquid fuel and oxygen; an evaporator 102 which converts water and liquid fuel to water vapor and vapor of liquid fuel; combustion apparatuses 107 and 701 which form a high temperature gas to heat the evaporator 102; and a means of supplying fuel to the fuel reformer 103; and comprises: a fuel flow adjustor 704 to adjust the fuel amount supplied to the combustion apparatus 701; a bypass control valve 703 to adjust the amount of the combustion gas flow bypassing the evaporator 102 and passing through a bypass 702; and a means of controlling the both in accordance with an acceleration rate and load required by the moving body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a fuel reforming system for mobile bodies.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional example of a fuel reforming system for a moving body represented by a fuel cell vehicle.

A mixed liquid of water and methanol, which is a fuel, in the fuel tank 100 is sent to an evaporator 102, heated and evaporated, and becomes a mixed gas of water and methanol and sent to a mixer 180. Further, air is sent from the compressor 104 to the mixer 180, and the mixed vapor and air are mixed by the mixer 180 and then sent to the ATR (auto thermal reactor) 103.

The ATR 103 reforms fuel, that is, methanol as a fuel, using water and oxygen in the air by the following catalytic reaction to produce a hydrogen-rich reformed gas.

[0005]

[Formula 1]

The operating temperature of ATR103 is 300 to 600 ° C., and a reformed gas containing carbon monoxide on the order of several percent is obtained by thermodynamic chemical equilibrium. Since carbon monoxide poisons the anode electrode catalyst made of platinum or the like of the polymer electrolyte fuel cell 200 and significantly reduces its activity, the shift reactor 105 and PROX (selective oxidation) reactor 106 described below are used. With a carbon monoxide cleaner system consisting of several tens to 100 ppm
It is necessary to reduce the amount of carbon monoxide and supply it to the fuel cell 200.

The reformed gas containing carbon monoxide on the order of several percent is sent to the shift reactor 105 to reduce carbon monoxide. The operating temperature of the shift reactor 105 is 200 to 300 ° C., and thermodynamic chemical equilibrium results in a reformed gas containing carbon monoxide in the order of several percent. The required oxygen is supplied by the compressor 104 as air. PROX reactor 106
Then, the oxidation reaction is performed in a hydrogen atmosphere.

In the fuel cell 200, it is impossible to use all the hydrogen in the reformed gas, and the reformed gas that has been used for power generation with some hydrogen left and power generation with some oxygen left The spent air and the air are sent to the exhaust gas combustor 107 filled with a catalyst and burned. The high-temperature exhaust gas thus obtained is sent to the evaporator 102 and reused as energy for evaporating methanol and water.

Reference numeral 500 is a flow rate control valve for controlling the flow rate of air supplied to the PROX reactor 106, 501 is a flow rate control valve for controlling the flow rate of air supplied to the ATR reactor 103, and 502 is the fuel cell 2.
This is a flow rate control valve that controls the flow rate of the air supplied to the 00 air electrode. 510 is a pressure control valve for adjusting the operating pressure of the fuel electrode of the fuel cell 200, and 511 is a pressure control valve for adjusting the operating pressure of the air electrode of the fuel cell 200. 520 and 521 are pressure sensors that detect the operating pressures on the fuel electrode side and the air electrode side of the fuel cell 200, and the pressure is adjusted so that these pressures become the same.

Reference numeral 400 is a controller for managing the energy of the moving body, and sends an operation load signal 402 of the reforming system to the controller 401. Controller 401 is the operating load signal
Based on 402, the pump 170 is driven so that the fuel flow rate and the air flow rate required for the ART reactor 103 are controlled, the flow rate of the liquid fuel supplied to the evaporator 102 is controlled, and the flow rate control valve 50
1 controls the amount of supply air used for fuel reforming. 601,
Reference numerals 602 are flow rate sensors for the fuel flow rate and the air flow rate, which are used for fuel reforming.

When it is necessary to quickly raise the temperature of the evaporator 102 at the time of start-up, the reformed gas does not pass through the fuel cell 200 and is bypassed by the bypass 700.
There is also an example in which the temperature is directly supplied to the exhaust gas combustor 107 to accelerate the temperature rise of the evaporator 102 (Japanese Patent Laid-Open No. 2000-63104).

There is also an example in which two or more evaporators are provided to cope with load fluctuations, and a combustion burner is provided for each of them to control the fuel amount in conjunction with the load (Japanese Patent Laid-Open No. 2000-10046).
2).

[0013]

[Problems to be Solved by the Invention] These reforming systems may interlock with the accelerator (direct interlock with the accelerator opening) or via the controller 400 under transient operating conditions during load changes (acceleration / deceleration, etc.). ) And the evaporator 102
Flow rate of input fuel (liquid) supplied to
There is a problem that a phase difference occurs between the output and the mass flow rate of output fuel (steam) (hereinafter referred to as output). Due to this phase difference,
There is a problem that the required amount of electricity cannot be generated or the battery capacity increases when the battery compensates for the excess or deficiency of the amount of electricity.

Therefore, the present invention has been made in view of the above problems, and there is no phase difference between the input and output of the evaporator under transient operating conditions, or the output is linked with the accelerator opening. An object of the present invention is to provide a controller for a fuel reforming system for a mobile body, which can obtain a mass flow rate.

[0015]

A first aspect of the present invention is a fuel reformer for producing a reformed gas containing hydrogen by using steam, vapor of a gaseous fuel or liquid fuel, and a gas containing oxygen. Hydrogen of the reformed gas, a fuel cell that receives supply of oxygen to generate electricity by a chemical reaction, an evaporator that generates the water vapor or vapor of the liquid fuel from water or liquid fuel, and exhaust gas from the fuel cell A fuel for a mobile body having a first combustor for generating exhaust combustion gas for heating the evaporator by burning, and a means for supplying the steam and the vapor of a gaseous fuel or a liquid fuel to the fuel reformer. In the reforming system, a second combustor that includes a fuel flow rate adjusting device that adjusts the fuel flow rate, and that burns the fuel whose fuel flow rate is adjusted to generate high-temperature gas for heating the evaporator. A bypass passage for bypassing the evaporator to flow the exhaust combustion gas, a bypass control valve for adjusting the opening degree of the bypass passage, an acceleration required for the moving body, and the fuel flow rate according to a load. An adjusting device and means for controlling the bypass control valve are provided.

In a second aspect based on the first aspect, the fuel flow rate to the second combustor is increased when the fuel input acceleration is large in the positive direction.

In a third aspect based on the first or second aspect, when the fuel input acceleration is large in the negative direction,
The opening degree of the bypass control valve is increased.

In a fourth aspect of the invention, in any one of the first to third aspects of the invention, the fuel flow rate to the second combustor increases as the load decreases when the acceleration is positive, and the load increases as the load increases when the acceleration is negative. Reduce the bypass control valve opening.

A fifth aspect of the present invention is the fuel cell system according to any one of the first to fourth aspects, wherein the second combustion is performed in accordance with a difference between a generated vapor mass flow rate required for the evaporator and an actual generated vapor mass flow rate. The flow rate of fuel to the container and the opening of the bypass control valve are controlled.

In a sixth aspect based on the fifth aspect, the fuel flow rate to the second combustor is first set by a map based on the acceleration of the generated vapor mass flow rate required for the evaporator, and the demand is set. The generated steam mass flow rate and the actual generated steam mass flow rate are detected to correct the map value.

In a seventh aspect based on any one of the first to sixth aspects, when the acceleration is positive, the fuel mass flow rate actually input to the evaporator is made equal to the required generated steam mass flow rate. The mass flow rate of fuel that is actually input to the evaporator is controlled with a larger acceleration in the negative direction than with the required generated steam mass flow rate when the acceleration is negative.

[0022]

According to the first invention, the phase difference between the input and output of the evaporator during the transient operation can be reduced.

According to the second aspect of the invention, as the acceleration increases in the positive direction, the heat quantity in the evaporator also increases, but the heat quantity of the hot gas increases as the fuel supply to the combustor increases. In addition, it is possible to suppress a shortage of heat of evaporation and reduce the phase difference between the input and output of the evaporator during acceleration.

According to the third aspect of the invention, as the acceleration increases in the negative direction, the excess amount of heat of the evaporator also increases. However, by increasing the opening of the bypass control valve, the excess amount of heat is released. It is possible to reduce the phase difference between the input and output of the evaporator during deceleration.

According to the fourth aspect of the invention, when a positive acceleration is required, more heat is supplied to the evaporator in the early stage of acceleration with a small load, and when negative acceleration is required, a larger load is used. Since the proportion of the heat released to the total amount of heat generated in the combustor becomes small, the phase difference generated between the input and output of the evaporator at the time of positive or negative acceleration can be made small by making the opening degree of the bypass control valve small.

According to the fifth aspect of the invention, the amount of heat supplied to the evaporator can be adjusted by the difference between the actual input and output of the evaporator, so that the phase difference between the input and output of the evaporator during transient operation can be reduced. .

According to the sixth aspect of the invention, the map can be corrected by the difference between the actual input and output of the evaporator and the amount of heat supplied to the evaporator can be corrected, so that the phase difference between the input and output of the evaporator can be made smaller. it can.

According to the seventh aspect of the invention, since the amount of heat supplied to the combustor at the time of positive acceleration is small, the amount of fuel supplied to the combustor can be made small. Since heat that escapes by bypassing the evaporator can be reduced during negative acceleration, heat loss can be reduced.

[0029]

FIG. 2 shows the configuration of a reforming system in which the control of the present invention is performed. In addition to the structure of the prior art shown in FIG. 1, a combustor 701 independent of the exhaust gas combustor 107, an injector 704 for controlling the fuel supplied from the fuel tank 100 to the combustor 701, and a high temperature gas from the exhaust gas combustor 107 Has an evaporator 10
Bypass passage 702 for bypassing 2, bypass passage
A bypass flow rate control valve 703 is installed on the 702 to control the bypass flow rate, and other configurations are the same as those of the conventional art. The injector 704 and the bypass flow control valve 703 are controlled by the controller 401.

Next, the control method in the first embodiment is shown in FIGS. 5 and 6 (acceleration / deceleration, respectively), and the resulting evaporation characteristics during acceleration / deceleration are shown in FIGS. 3 and 4. Here, acceleration is positive acceleration and deceleration is negative acceleration.

When the vehicle is accelerated, the fuel flow rate to the combustor 701 is controlled by the injector 704 according to the map shown in FIG. (A to f in FIG. 5 correspond to a to f in FIG. 3) That is, the fuel flow rate increases as the load decreases and the input acceleration increases, and the fuel flow decreases as the load increases and the acceleration decreases. In other words, When a certain input acceleration is generated, the fuel flow rate is set to decrease as the load increases, and the fuel flow rate is controlled according to a map according to the condition that changes momentarily.

When the load is large, that is, when the flow rate of the fuel supplied to the evaporator 102 is large, the exhaust gas from the fuel cell 200 also increases, and the high temperature gas generated in the combustor 107 also increases. Therefore, the high-temperature gas generated in the combustor 701 can be sufficiently vaporized even with a small amount, so that the fuel supplied to the combustor 701 is reduced. Further, as the acceleration increases, the amount of heat in the evaporator 102 becomes insufficient, so the combustor 7
By increasing the flow rate of the fuel supplied to 01, it is possible to suppress the shortage of the heat amount of the evaporator 102. As a result, the generated fuel vapor mass fuel characteristic (output) in FIG. 3 is improved from the broken line (when this control is not performed) to the solid line, and the phase difference between the input and output during acceleration can be suppressed.

During deceleration, the opening degree of the bypass control valve 703 is controlled according to the map shown in FIG. (A to f of FIG. 6 correspond to a to f of FIG. 4, respectively) That is, the opening of the bypass control valve 703 decreases as the load increases and the input deceleration decreases, and the bypass control decreases as the load decreases and the deceleration increases. Valve 70
The opening degree of 3 is increased, in other words, if the deceleration is the same, the opening degree of the bypass control valve 703 is set to be smaller as the load is larger, and the bypass according to the map changes according to the momentary conditions. The opening degree of the control valve 703 is controlled.

If the deceleration is constant when the load is large and when the load is small, the amount of reduction of the fuel supplied to the evaporator 102 is the same, and the amount of heat to be supplied to the evaporator 102 is also the same. Here, when the amount of decrease in the amount of heat to be supplied to the evaporator 102 is the same, the amount of heat originally supplied to the evaporator 102 is larger when the load is large compared to when the load is small. The rate of decrease in the amount of heat originally supplied to the evaporator 102 can be small. That is, the ratio of the flow rate to be bypassed to the original flow rate may be smaller under high load, so the bypass control valve
The opening degree of 703 may be small. As a result, the generated vapor fuel vapor mass flow rate characteristic (output) in FIG. 4 is improved from the broken line to the solid line, and the phase difference between the input and output during deceleration can be suppressed.

According to the above control, when acceleration is requested, a larger amount of heat is supplied to the evaporator 102 in the early stage of acceleration with a small load, and when deceleration is requested, it is supplied to the evaporator 102 in an early stage of deceleration with a large load. The generated heat can be released more, and the phase difference between the input and the output can be suppressed.

The input acceleration of the evaporator 102 is the time rate of change of the required generated steam mass flow rate, which is determined by the accelerator opening, and the load is a load with a rating of 4/4. Proportional to flow rate.

9 and 10 show control maps used in the control method of the second embodiment, and FIGS. 7 and 8 show evaporation characteristics during acceleration / deceleration obtained as a result of the control.

The difference between the signal (output) and the input of the flow rate sensor 601 for detecting the mass flow rate of the vapor generated in the evaporator 102 is detected, and the fuel flow rate to be supplied to the combustor 701 and the bypass control valve are detected from the difference. The opening degree of 703 is controlled. 7,
Similar to the above, FIG. 8 shows the input / output characteristics during acceleration / deceleration and the difference (Δq) between the output and the input. The broken lines in FIGS. 7 and 8 show the generated steam mass flow rate characteristics when the present embodiment is not performed, and the solid lines show the generated steam mass flow rate characteristics when the present control is adopted.

When Δq is negative (input>output; during acceleration), the fuel flow rate is controlled according to the map shown in FIG. That is, as the difference between the input and the output becomes larger, the fuel flow rate to the combustor 701 is increased, and the evaporator 102 is further heated to increase the output. After that, as the difference between the input and the output becomes smaller, the fuel flow rate is decreased, and the heating of the evaporator 102 is started by the exhaust gas from the fuel cell 200 which increases as the output of the evaporator 102 increases.

On the other hand, when Δq is positive (input <output; during deceleration), the bypass control valve 703 is used according to the map shown in FIG.
Control the opening degree of. That is, as the difference between the input and the output becomes larger (the output becomes larger than the input), the opening degree of the bypass control valve 703 is increased to release the excess heat, and thereafter, as the difference between the input and the output becomes smaller. Bypass control valve 70
Decrease the opening of 3.

In this way, the amount of heat supplied to the evaporator 102 can be adjusted by the difference between the actual input and output of the evaporator 102, so that the generated steam mass flow rate characteristic can be brought close to the required generated steam mass flow rate characteristic, and the transient steam mass flow rate characteristic can be obtained. Evaporator during operation
The phase difference between the input and output of 102 can be made smaller.

The control method of the third embodiment is shown in the flowchart of FIG. Similar to the maps of FIGS. 5 and 6 based on the acceleration / deceleration of the input (liquid), the maps of FIG. 9 and FIG.
By controlling the fuel injection flow rate of the fuel and the opening degree of the bypass control valve 703, the evaporator 102 can be controlled as shown by the chain lines in FIGS.
It is possible to reduce the phase difference between the input (liquid) and the output (vapor).

Specifically, in the flowchart of FIG. 11, first, the initial values of the flow rate of fuel supplied to the combustor 701 and the opening degree of the bypass control valve 703 are given from FIGS.
In step S1, the input (liquid) generated under the control and the generated steam mass flow rate (output) are detected. Then step S
In 2, the input / output phase difference (Δq) is calculated. Proceeding to step S3, the correction according to the value is performed in FIGS. 9 and 10, and the map is corrected as indicated by the alternate long and short dash line in FIGS. Next, in step S4, it is determined whether or not the correction result Δq is an allowable value. If it is not an allowable value, the process returns to step S3 to perform the correction again, and if it is an allowable value, it is determined that no further correction is necessary. Then, the above control is repeated thereafter. With such control, the phase difference between the input and the output can be reduced in the control from the next time as shown by the alternate long and short dash line in FIGS. Thus, the actual evaporator 102
Since the map can be corrected by the difference between the input and the output of the above and the amount of heat supplied to the evaporator can be corrected, the phase difference between the input and output of the evaporator can be made smaller.

The generated steam mass flow rate characteristics in the fourth embodiment are shown in FIGS.

The input (liquid) flow rate characteristic with respect to the required steam output is determined by taking the phase difference into consideration. That is, as shown in FIG. 12, a flow rate characteristic (solid line) having a large acceleration with respect to the required steam output (dotted line) during acceleration, and a large deceleration with respect to the required steam output (dotted line) during deceleration as shown in FIG. A fuel mass flow rate along a flow rate characteristic (solid line) with is input to the evaporator 102. Although such control causes a difference between the input and output at the initial stage of acceleration or deceleration, the acceleration positively increases the contact heat transfer area of the liquid and the two phases, and during the deceleration, the contact heat transfer interruption of the liquid and the two phases is interrupted. By reducing the area, it becomes possible to bring the generated steam mass flow rate (dotted line) close to the required generated steam mass flow rate characteristic (solid line) as shown in FIGS.

Here, in the fourth embodiment, the followability of steam generation during a transition can be improved without using the combustor 701 or the bypass control valve 703. Therefore, if the fourth embodiment is applied to the first to third embodiments, the amount of heat supplied to the combustor 701 at the time of acceleration can be small by the amount that the followability of steam generation can be improved, and thus the combustor 701 can be used. The amount of fuel supplied to the fuel tank can be reduced, and the heat that bypasses the evaporator 102 and escapes can be reduced during deceleration, so heat loss can be reduced.

The bypass control valve 703 may be controlled during acceleration and the fuel flow rate of the combustor 701 may be controlled during deceleration so that the difference between the input and output of the evaporator becomes small. As described above, it is needless to say that the present invention is not limited to the above embodiment and various modifications can be made within the scope of the technical idea described in the claims.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a reforming system in a conventional technique.

FIG. 2 is a configuration diagram of a reforming system in the present embodiment.

FIG. 3 is an evaporation characteristic during acceleration according to the related art and the first embodiment.

FIG. 4 is an evaporation characteristic during deceleration of the related art and the first embodiment.

FIG. 5 is a map of fuel flow rate and load during acceleration according to the first embodiment.

FIG. 6 is a map of the opening and load of the bypass control valve during deceleration according to the first embodiment.

FIG. 7 is an evaporation characteristic at the time of acceleration in the related art and the second embodiment.

FIG. 8 is an evaporation characteristic at the time of deceleration of the related art and the second embodiment.

FIG. 9 is a map of fuel flow rate and load during acceleration according to the second embodiment.

FIG. 10 is a map of the opening degree and load of the bypass control valve during deceleration according to the second embodiment.

FIG. 11 is a flowchart for controlling the reforming system according to the third embodiment.

FIG. 12 is a generated steam mass flow rate and a required generated steam mass flow rate during acceleration according to the fourth embodiment.

FIG. 13 is a generated steam mass flow rate and a required generated steam mass flow rate during deceleration of the fourth embodiment.

[Explanation of symbols]

100 fuel tank 102 evaporator 103 Auto Thermal Reactor (ATR) 104 compressor 105 shift reactor 106 PROX reactor 107 Exhaust gas combustor 170 Fuel pump 180 mixer 200 fuel cell 400 controller 401 controller 402 Operation load signal Air flow control valve to 500 PROX reactor 501 ATR Reactor Air Flow Control Valve 502 Air flow control valve to fuel cell 510 Fuel electrode pressure control valve 511 Air electrode pressure control valve 520 Fuel electrode side pressure sensor 521 Oxygen electrode side pressure sensor 601 Fuel supply flow rate sensor 602 Supply air flow rate sensor 700 Fuel cell 200 bypass 701 Combustor 702 Evaporator 102 bypass passage 703 Bypass control valve 104 injector

Claims (7)

[Claims] 1. A fuel reformer for producing a reformed gas containing hydrogen by using steam, vapor of a gaseous fuel or liquid fuel, and a gas containing oxygen, and hydrogen and oxygen contained in the reformed gas. Of the fuel cell for generating electric power by a chemical reaction in response to the supply of water, an evaporator for generating water vapor or vapor of the liquid fuel from water or liquid fuel, and heating the evaporator by burning exhaust gas from the fuel cell. In the fuel reforming system for a moving body, the first combustor for generating exhaust combustion gas for controlling the fuel reformer, and means for supplying the steam and the vapor of the gaseous fuel or the liquid fuel to the fuel reformer are adjusted. A second combustor for producing a high temperature gas for heating the evaporator by burning the fuel whose fuel flow rate is adjusted; and bypassing the evaporator. A bypass passage for flowing the exhaust combustion gas, a bypass control valve for adjusting the opening degree of the bypass passage, and the fuel flow rate adjusting device and the bypass control valve according to the acceleration and load required for the moving body. A control device of a fuel reforming system for a mobile body, comprising: a control means. 2. The control device for a fuel reforming system for a moving body according to claim 1, wherein the fuel flow rate to the second combustor is increased when the acceleration is large in the positive direction. 3. When the acceleration is large in the negative direction,
The control device for a fuel reforming system for a mobile body according to claim 1, wherein the opening degree of the bypass control valve is increased. 4. When the acceleration is positive, the fuel flow rate to the second combustor increases as the load decreases, and when the acceleration is negative, the opening degree of the bypass control valve decreases as the load increases. A control device for a fuel reforming system for a mobile body according to any one of 1. 5. The fuel flow rate to the second combustor and the opening degree of the bypass control valve are controlled according to the difference between the generated steam mass flow rate required for the evaporator and the actual generated steam mass flow rate. The control device for a fuel reforming system for a mobile body according to claim 1. 6. The fuel flow rate to the second combustor is first set by a map based on the acceleration of the generated steam mass flow rate required for the evaporator, and the required generated steam mass flow rate and the actual flow rate are set. The control device for a fuel reforming system for a mobile body according to claim 5, wherein the generated steam mass flow rate is detected to correct the map value. 7. When the acceleration is positive, the fuel mass flow rate actually input to the evaporator is larger than the required generated steam mass flow rate, and when the acceleration is negative, the fuel mass flow rate is actually supplied to the evaporator. The fuel mass flow rate to be input is a large acceleration in the negative direction as compared with the required generated steam mass flow rate,
The control device for a fuel reforming system for a mobile body according to any one of claims 4 to 6, which controls each.