JP2002305015A - Operation method of fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a fuel cell system obtained by combining a hydrogen storage container with a hydrogen manufacturing unit at a high efficiency. SOLUTION: This is an operation method of the fuel cell system in which hydrogen obtained by the reforming of hydrocarbons in a membrane reformer and purified is made to pass through a pair of hydrogen storage containers, to be stored, and the stored hydrogen is released and supplied to the fuel cell. The membrane reformer is operated at a constant output, and the storage and release of hydrogen is operated by switching by means of the pressure in the respective hydrogen storage containers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of reforming a hydrocarbon by a membrane reformer and purifying the purified hydrogen by a hydrogen-absorbing alloy container, further purifying and storing the hydrogen, releasing the hydrogen, and using the hydrogen as a fuel for a fuel cell. The operation method of the fuel cell system.

[0002]

2. Description of the Related Art Hydrogen is a basic raw material for various uses and is also used as a fuel for fuel cells. As a method for converting hydrocarbons, which is one of the industrial methods for producing hydrogen, there are a steam reforming method and a partial combustion method. In the steam reforming method, a reformer is used, and hydrocarbons such as methane, ethane, propane, natural gas, city gas, and LP gas are reformed with steam to be converted into a hydrogen-rich reformed gas.

[0003] In addition to hydrogen as the main component, C
It contains by-products such as O and CO ₂ and surplus H ₂ O. Therefore, if the reformed gas is used as it is in the fuel cell, the cell performance will be impaired. Among the fuel cells, about 1% of CO is contained in hydrogen gas used in a phosphoric acid fuel cell (PAFC), and 100 pp in a polymer electrolyte fuel cell (PEFC).
m (10 pp depending on the constituent materials such as the fuel electrode)
m) is the limit, and when these are exceeded, the battery performance is significantly deteriorated. Therefore, it is necessary to remove those by-products before introducing them into the fuel cell.

One of the methods for purifying hydrogen to obtain such high-purity hydrogen is a hydrogen permeable membrane method. The purification by the hydrogen permeable membrane method may be performed separately from the generation of the reformed gas, but the membrane reformer (membrane reactor) is an integrated apparatus in which both are performed by one apparatus. FIG.
FIG. 4 is a diagram schematically showing a membrane reformer. The heat generated in the burner is used for reforming the raw material gas such as city gas, and the raw material gas is reformed in the catalyst layer to become a hydrogen-rich reformed gas. Hydrogen in the reformed gas selectively permeates through a hydrogen permeable film such as a Pd film or a Pd alloy film and is extracted as purified hydrogen.

However, a membrane reformer requires a large surface area of the hydrogen permeable membrane in order to increase the yield of purified hydrogen, and therefore, the size of the apparatus is increased and the cost is increased. Also, in order to increase the yield of purified hydrogen, it is necessary to increase the pressure difference between the primary side and the secondary side of the membrane. For this reason, the pressure on the primary side is increased, and the sweep gas (water vapor) is
This not only reduces the energy efficiency of the system, but also requires a water vapor separator.
FIG. 2 is a diagram showing this mode. Nevertheless, since the purity of purified hydrogen depends on the quality of the hydrogen-permeable membrane, a high-quality membrane without pinholes must be manufactured, which also increases costs.

On the other hand, when a polymer membrane is used as the hydrogen permeable membrane, the membrane reformer type cannot be used in terms of heat resistance and the like. In the polymer membrane method, 90 purification steps are required.
%, And it is necessary to carry out in a multistage manner. In addition, not only a pressure such as several kG to 150 kG / cm ² is required as an operating pressure, but also the hydrogen pressure after separation decreases. FIG. 3 is a diagram showing this mode.

The reformed gas from the reformer is supplied to the first (previous stage)
The purified gas obtained is passed through a polymer membrane and the resulting purified gas is passed through a second (later) polymer membrane. Thus, it is passed through the required number of polymer membranes. This not only complicates the system, but also reduces the yield of purified hydrogen. Moreover, these methods using a hydrogen permeable membrane can only purify hydrogen and do not have a hydrogen storage function of supplying a predetermined required amount according to demand.

Accordingly, the present inventor has proposed a crude purified hydrogen obtained by reforming and purifying hydrocarbon with a membrane reformer (in addition,
Although the purity of the hydrogen is 99.99% or more, since it is further purified by a hydrogen storage alloy, it is roughly purified hydrogen in the sense that it is not purified by the hydrogen storage alloy). A fuel cell system has been previously developed in which hydrogen is separated and purified and stored by passing it alternately through a filling container, and the stored hydrogen is released and supplied to the fuel electrode of the fuel cell (Japanese Patent Application No. 11-110). No. 144043).

[0009]

SUMMARY OF THE INVENTION The present invention is based on the fuel cell system according to the above-mentioned development, and by adding various measures such as automating the operation of the fuel cell system, it is possible to obtain a high efficiency in terms of hydrogen yield and power generation efficiency. It is an object of the present invention to provide a new and useful driving method with high practicality such as being able to be used.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to a fuel cell in which hydrocarbons are reformed by a membrane reformer and purified hydrogen is alternately stored and passed through a pair of hydrogen storage containers to release the stored hydrogen. An operation method of a fuel cell system configured to supply, characterized in that a membrane reformer is operated at a constant output, and hydrogen storage and release are switched by switching the pressure in each hydrogen storage container. The present invention provides a method for operating a fuel cell system.

Further, the present invention provides a fuel cell in which hydrocarbons are reformed by a membrane reformer, and purified hydrogen is alternately stored and passed through a pair of hydrogen storage containers, and the stored hydrogen is released and supplied to a fuel cell. Operating the membrane reformer at a constant output, and switching the storage and release of hydrogen with the pressure in each hydrogen storage container, at the time of preparing for storage startup. Set pressure P ₁ for checking the pressure inside the hydrogen storage container, set pressure P ₂ for checking the pressure inside the hydrogen storage container during storage, set pressure P ₃ for checking the pressure inside the hydrogen storage container during transition to release, and release Set pressure P ₄ to check the pressure in the hydrogen storage container at the time of transition from
Storage of hydrogen in these P ₁ to P ₄ and based on the respective hydrogen storage container, a method of operating a fuel cell system which is characterized in that the release of hydrogen from the hydrogen storage container.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, hydrocarbons are reformed by a membrane reformer and purified hydrogen is alternately stored and passed through a pair of hydrogen storage containers, and the stored hydrogen is released and supplied to a fuel cell. An operation method of the fuel cell system configured as described above. In the present invention, hydrocarbons are reformed with a membrane reformer to form a hydrogen-rich reformed gas and purified. The hydrogen obtained here is passed through a pair (two) of hydrogen storage alloy filled containers alternately to further purify and occlude. Then, the stored hydrogen is released and supplied to the fuel electrode of the fuel cell. Any hydrocarbon can be used as long as it can be reformed, but preferably natural gas, city gas, or petroleum gas is used. In this specification, a hydrogen storage alloy-filled container, that is, a container filled with a hydrogen storage alloy is abbreviated as a hydrogen storage container. As the fuel cell, both PEFC and PAFC are used, and preferably, PEFC is used.

As described above, in order to increase the yield of high-purity hydrogen with a membrane reformer, the size of the apparatus is increased, and it is necessary to increase the pressure on the primary side and to flow a sweep gas to the secondary side. There were problems. In the present invention, these problems are solved by using a hydrogen storage alloy, and the hydrogen obtained by the membrane reformer is stored as high-purity hydrogen having a purity of 99.999% or more by the hydrogen storage alloy. Releases hydrogen and uses it as fuel for fuel cells.

In the present invention, in operating the fuel cell system, it is important to operate the membrane reformer (referred to as "hydrogen production apparatus" in this specification as appropriate) continuously and at a constant output. Such continuous operation of the hydrogen production apparatus at a constant output was made possible for the first time by using the hydrogen storage alloy in the present invention, thereby reducing the size of the hydrogen production apparatus and increasing the efficiency of the hydrogen production apparatus. You can drive with

In the present invention, the hydrogen storage alloy (Hydrogen S)
The torage alloy is not particularly limited as long as it has these characteristics, and any of them can be used. Examples include TiFe _0.9 Mn _0.1 , Mg ₂ Ni, CaNi
S, LaNi ₅ , LaNi _4.7 Al _0.3 , MmNi _4.5 Al
_0.5 (Mm = misch metal), MmNi _4.15 Fe _0.85 (M
m = mish metal).

FIG. 4 is a diagram showing an example of an embodiment of a fuel cell system applied to the present invention. Raw material gas (hydrocarbon gas)
Is reformed and purified by a hydrogen production apparatus. Then, the purified hydrogen is passed through a hydrogen storage container to be further purified and stored. The hydrogen production equipment has two hydrogen storage containers MA and MB.
Are connected. The hydrogen storage containers MA and MB may be connected as a group of the hydrogen storage containers MA and a group of the hydrogen storage containers MB, and two or more hydrogen storage containers may be connected as each group. In the hydrogen production apparatus, a reformed gas is generated from a raw material gas, and the obtained reformed gas is purified by a hydrogen permeable membrane therein to obtain purified hydrogen, which is passed through a hydrogen storage container.

FIG. 4 shows a case where the hydrogen storage container is operated in a batch type, but the same applies to a case where the hydrogen storage container is a vented type. Hydrogen from the hydrogen production device is further purified and stored in the hydrogen storage container MA. Hydrogen storage container MB
Releases high-purity hydrogen absorbed in the previous stage,
Provided to FC. By switching the switching valves S and T, the hydrogen from the hydrogen production device is further purified and stored in the hydrogen storage container MB, and the high-purity hydrogen stored in the previous stage is released from the hydrogen storage container MA, and the hydrogen is stored in the PEFC. Supplied.

In the present invention, as described above, a hydrogen production apparatus, two hydrogen storage vessels MA and MB installed in parallel with the hydrogen production apparatus, and a fuel cell system in which a PEFC is connected thereto are efficiently used. drive. 5 to 7 are diagrams showing examples of the mode of operation. Each symbol in FIGS. 5 to 7 is described in correspondence with each other.

FIG. 5 is a diagram showing the arrangement of the hydrogen production system, the PEFC, the hydrogen storage container, etc., the hydrogen gas system piping, the heat medium system piping, the control electric system wiring, etc., and the wiring arrangement and their relationships. is there. Hydrogen produced and purified by the hydrogen production device is introduced into the hydrogen storage vessel MA or MB via a conduit (hydrogen supply line). A purge valve VA is provided in the middle of the conduit, and the gas with low hydrogen purity immediately after the start of hydrogen production is
It is purged without being introduced into the hydrogen storage container. Switching of the hydrogen flow to the hydrogen storage container MA or MB is performed by the solenoid valve HV.
This is performed by opening and closing operations of 1-1 and HV1-2. The supply of hydrogen from the hydrogen storage container MA or MB to the PEFC is performed by opening and closing the solenoid valves HV2-1 and HV2-2. In addition, these switching may be performed by a three-way valve.

When the hydrogen production device is a membrane reformer, it is desirable to store hydrogen at a low pressure in a hydrogen storage container in order to increase the yield of hydrogen. For this purpose, it is preferable to store hydrogen in a certain pressure range. Therefore, in the present invention, the start and end of occlusion are determined based on the pressure in the container. On the other hand, when releasing the stored hydrogen and supplying it to the PEFC, it is necessary to supply the hydrogen in a certain pressure range. Therefore, in the present invention, the start and end of the discharge are also determined based on the pressure in the container.
As described above, the present invention is very effective in terms of safety because the operation is based on those pressures.

Incidentally, a hydrogen producing apparatus such as a steam reformer or a membrane reformer has an operating temperature of 500 to 700.
Since the temperature is as high as about ° C., it takes time to start and stop, and energy loss occurs when starting and stopping. Therefore, it is desirable that the hydrogen production apparatus be operated continuously.
Therefore, in the present invention, the hydrogen production apparatus is operated continuously. That is, the hydrogen production apparatus is continuously operated to produce hydrogen, and the produced hydrogen is continuously supplied to the hydrogen storage container.
And store and release in an optimal pressure range.

In the present invention, the hydrogen storage container M for hydrogen is used.
It is important to operate by switching the storage of A or MB and the supply of hydrogen to the PEFC with the pressure in the hydrogen storage container MA and MB. Therefore, the hydrogen storage container MA
The pressure inside is measured by a pressure gauge 1 and the pressure inside the hydrogen storage container MB is measured by a pressure gauge 2. The measurement of the pressure in these containers may be performed at the outlet piping of those containers, and FIG. 5 shows this case. T1 to T12 are temperature sensors arranged at respective locations. Since the operation of storing and releasing hydrogen is performed with pressure, the temperature of each part in the present system is controlled in accordance with the pressure.

Heating is required to release hydrogen from the hydrogen storage vessel MA or MB, and cooling is required to store hydrogen in the hydrogen storage vessel MA or MB. This heating and cooling are performed by a heating medium piping. For this reason, a heating system pipe including a three-way automatic valve V0-1, a hot water tank (= hot water tank: heated by a heater), a circulation pump M1, an automatic flow control valve CV1, a flow meter FS1, and a three-way automatic valve V1-1, ,
Three-way automatic valve V0-2, cooler, cooling water tank, circulation pump M
2. Two lines of cooling system piping including an automatic flow control valve CV2, a flow meter FS2, and a three-way automatic valve V1-2 are arranged. In addition, in the figure, the code | symbol A of the lower part of each three-way automatic valve,
B is a branch pipe, a branch pipe A is a pipe for passing hot water or cooling water to the hydrogen storage container MA side, and a branch pipe B is a pipe for passing hot water or cooling water to the hydrogen storage container MB side.

The heating medium supplied to the hydrogen storage vessel MA or MB is switched by operating each valve of the heating system pipe using the hot water as a heat medium and operating each valve of the cooling system pipe using the cooling water as a refrigerant. For example, the hydrogen storage container MB
When hydrogen is released from the valve, the three-way automatic valve V0-1 and the three-way automatic valve V1-1 are switched to the hydrogen storage container MB side (that is, to the branch pipe B side from each of these valves), and At the time of storing hydrogen, the three-way automatic valves V0-2 and V1-2 move toward the hydrogen storage container MA (ie,
(To the branch pipe A side from each of these valves).

The control electric system wiring is for automatically controlling and performing the above operation. This control is performed by a sequencer (central control unit). In FIG. 5, the symbol “* 1”
Is an input signal to the sequencer, and reference numeral “* 2” is an output signal (control signal) from the sequencer. The sequencer receives each input signal * 1 and, based on this, issues each output signal * 2 to a controlled location to control. These controls are performed according to a conventional method.

FIG. 6 (a) shows the hydrogen production system (H, ie, H system) and the hydrogen storage system (M, M) at each stage S0 to S3 of the overall control (S) in the present fuel cell system.
That is, M system) (= hydrogen storage container MA + hydrogen storage container M
B) and the state of PEFC (F, that is, F-based). FIG. 6B shows each stage H0 of the hydrogen production apparatus (H).
3 shows the open / closed state of the valve VA in H4. As shown in FIG. 5, the valve VA is disposed in a hydrogen supply line to the hydrogen storage containers MA and MB. FIG. 6 (c)
Are valves HV1-1 and HV1-1 in each stage MA0 to MA7 of the hydrogen storage container MA in the hydrogen storage system (M).
It shows the open / closed state of V2-1 and the presence / absence of circulation of cooling water and hot water to the hydrogen storage container MA. Cooling water is passed during purification and storage of hydrogen in the hydrogen storage container MA, and hot water is passed during release of hydrogen. It is ON when the respective heat mediums are passed, and OFF when not passed. FIG. 6D shows valves HV1-2 and HV in each stage MB0 to MB6 of the hydrogen storage container MB in the hydrogen storage system (M).
2-2 shows the open / closed state and the presence / absence of circulation of cooling water and hot water to the hydrogen storage container MB. Cooling water is passed during purification and storage of hydrogen in the hydrogen storage vessel MB, and hot water is passed during release of hydrogen. It is ON when the respective heat mediums are passed, and OFF when not passed. FIG.
The presence or absence of operation in each stage F0 to F5 of EFC (F),
That is, it indicates a power generation stop state or a power generation state in the PEFC.

FIG. 7 shows the overall control (S), the hydrogen production apparatus (H), the hydrogen storage container MA, and the hydrogen storage container MB corresponding to each step (each state) in FIG. 6 in the present fuel cell system. Hydrogen storage system (M) and PE
It is a figure in each stage of FC (F) which shows the process of the operation control from stop to start, start to operation, and operation to stop. In FIG. 7, "Y" indicates that the check criterion is satisfied, and "N" indicates that the check criterion is not satisfied.

Hereinafter, control modes of the fuel cell system from stop to start, start to operation, and from operation to stop will be sequentially described with reference to FIGS. As shown in FIG. 6A and FIG. 7A, S
0: From initial state (stop) S1: Starting, S1 to S
2: Shift from S2 to S3: stop during operation.

In the present invention, it is important to compare the detected pressure in the hydrogen storage container MA and the detected pressure in the hydrogen storage container MB with a preset control pressure, and to control the storage and release of hydrogen based on the control pressure. In this embodiment example, to set the control set pressure for the pressure of P ₁ to P _4. P ₁ is the set pressure to check the hydrogen storage container pressure when the hydrogen storage start preparation. Hydrogen storage container M by cooling with cooling water
When the pressure PA in A becomes smaller than P ₁ (that is, PA
<P ₁ when it comes to) the start-up Ready (OK). P ₂ is
This is a set pressure for checking the pressure inside the hydrogen storage container during hydrogen storage. For example the hydrogen storage vessel pressure within MA PA set pressure value P ₂ between less than (i.e. between a PA <P ₂₎
, The occlusion state is continued, and the pressure PA is equal to the set pressure P ₂
If it exceeds, the occlusion is completed. This state is also a state of preparation for release. P ₃ is a set pressure for checking the pressure in the hydrogen storage container at the time of transition to hydrogen release. When the pressure PA in the hydrogen storage vessel MA is greater than the set pressure value P ₃ by heating with hot water (i.e. PA> P ₃ become the)
It is in the state of release. P ₄ is a set pressure for checking the pressure in the hydrogen storage container at the time of transition from hydrogen release to release stop. Setting the pressure PA in the hydrogen storage vessel MA pressure P ₄ between larger (i.e. PA> while P is ₄₎ release is continued, at the time the pressure PA falls below the set pressure P ₄ (i.e. PA <P ₄ Then, the process moves to the end of release. Thereafter, as long as the overall control S system does not stop at S3, the process waits until the storage of the other hydrogen storage container MB is completed. The same applies to the hydrogen storage container MB. As these set pressures, for example, P ₁ = 1 atm,
P ₂ = 1 atm, P ₃ = 1.2 atm, P ₄ = 1.2 at
m.

Before starting the fuel cell system, that is, S
0: In the initial state, the hydrogen production system (H), the hydrogen storage system (M) including the hydrogen storage containers MA and MB, and the PEFC (F) are both in a stopped state. Starting the boot from this state, sequentially shifting from S1 to S2 to S3,
Along with this, hydrogen production equipment (H), hydrogen storage container MA,
The hydrogen storage container MB and PEFC (F) are transferred to each stage. Hereinafter, these controls and operations will be sequentially described.

<Hydrogen production apparatus (H)> Overall control S (= S
The system) receives a start command from the sequencer and shifts from S0: initial state to S1: start state. Accordingly, the hydrogen production apparatus H (= H system) changes from H0: stopped state to H1:
Move to running. At this time, the valve VA is open, and the gas discharged from the hydrogen production device at this stage is the valve VA.
Is purged. After the start preparation is completed, the operation shifts to H2: In operation. The start preparation completion check is performed when the temperature of the hydrogen production apparatus becomes equal to or higher than a specified value or when it is confirmed that a predetermined amount of hydrogen has been generated. Temperature and hydrogen generation can be performed by a sensor or the like according to a conventional method. When the S system shifts from S0 to S1, the hydrogen storage container MA simultaneously starts preparation for storage. MA is M
A2: When storage preparation is OK (completed), H2 to H
3: The process shifts to storing hydrogen, and the valve VA is switched to the closed state. At this time, the HV-1 is opened, and the hydrogen storage container MA is opened.
Is supplied with hydrogen. Then, according to the control of the hydrogen storage system M, hydrogen is supplied while being sequentially switched to the hydrogen storage containers MA and MB. Then, the overall control S system at this time shifts to S2: during operation. When the stop command is issued, the overall control S system shifts from S2 to S3: stop. Accordingly, the H system shifts from H3 to H4: stop, and the hydrogen production apparatus stops.

<Hydrogen storage system (M)> Overall control S
When (= S system) shifts from S0: initial state to S1: activation state, the hydrogen storage container MA (= MA system) sets MA0:
Transition from the stop state to MA1: (occlusion) start preparation state,
Cooling water is circulated and supplied to the MA. At this transition, when the pressure PA detected by the pressure gauge 1 in FIG. 5 becomes equal to or less than the set pressure value for control P ₁ = 1 atm (that is, PA <P ₁ ),
MA2: Start preparation OK (complete). Further, when the hydrogen production apparatus (H) is in the H2: operating state, the MA3 is in the occluded state, that is, in the occluded state. At this time, the valve HV1-1 changes from the closed state to the open state, and hydrogen starts to be stored.

When hydrogen is stored, the pressure in the hydrogen storage container MA gradually increases. In order to maintain the yield of hydrogen from the hydrogen production device, the pressure in the hydrogen storage container MA needs to be lower than a certain pressure. Therefore, if PA is P
Beyond ₂ = 1 atm (i.e. PA> P ₂ when it comes to), and ends the storage, MA4: shifts to the state of the storage completion. This state of MA4 is also ready for release. At this time, the other hydrogen storage container MB simultaneously shifts to the storage state (MB4 in FIG. 7: during storage), so that hydrogen from the hydrogen production device is continuously stored. The hydrogen storage container MA is MA
4: When the state shifts to the storage end state, warm water is circulated and supplied to the MA, and the pressure in the container rises. PA is P ₃ = 1.2
Above atm, transition to MA5: release. At this time H
V2-1 opens and hydrogen is supplied to the PEFC.

When hydrogen is released, the pressure in the hydrogen storage container MA gradually decreases. When the pressure in the MA becomes a pressure at which the PEFC cannot be operated, that is, when PA becomes P ₄
Release (PA <P ₄ ), the release is terminated and MA
6: The state shifts to the release end state. Then, the overall control system S
S3: Unless stopped, the process stands by until the storage of the other hydrogen storage container MB is completed. At this time, circulate cooling water to make it ready for storage,
MB is MB5: MA as soon as occlusion is completed
3: Switch to the state during occlusion. In this way, the state of MA6: release completed is shifted to MA3: occluded state,
The cycle from 3 to MA6 is repeated. Also for the hydrogen storage container MA, the state opposite to that of MA, that is, if MA is occluded, MB is released, and if MA is released, MB is occluded, and the same control as in the case of MA is performed.

<PEFC (F)> Overall control S (= S system)
Moves from the S0: initial state to the S1: activation state,
The PEFC (F) shifts from F0: initial state to F1: power generation standby. Next, when the hydrogen storage container MB enters MB2: release (hydrogen release state) or hydrogen releaseable state, F
1 to F2: Move to the stage of power generation 1 and generate power. At this time, hydrogen is automatically supplied from the hydrogen storage container MB in an amount consumed by power generation. When MB shifts to MB3: release stop and hydrogen release ends, PEFC (F) sets F3:
It shifts to power generation standby, and power generation stops once. Then, when the other hydrogen storage container MA enters the state of MA5: release or release of hydrogen, the PEFC (F) shifts to F4 and starts power generation. When MA becomes MA6: release ends, power generation is stopped again. . Thus, the overall control S (= S system)
3: Repeat this unless stopped.

Thus, the two hydrogen storage containers MA and M
For B, the operation is performed by alternately repeating the storage and release of hydrogen. In this case, it is ideal that the occlusion and release of MA and MB are simultaneously completed. That is, when the MB ends the release at the same time as the end of the storage of the MA, the release from the MA can be performed. In the present invention, it is preferred that the release is somewhat completed first. This is because, when the release from one hydrogen storage container, for example, MB, is completed first, the cooling water is circulated to the MB while the storage in the other hydrogen storage container, for example, MA is completed, and the storage standby state is established. Becomes
Thus, when the storage is switched from MA to MB,
Hydrogen can be stored at low pressure immediately from the beginning. As a result, not only can hydrogen be absorbed with a high yield from the beginning at the time of switching, but also the hydrogen produced in the hydrogen producing apparatus can be continuously and continuously stored. On the other hand, since hydrogen is not continuously released, a time zone occurs in which the PEFC cannot generate power. In such a case, if power from the system is used, there is no problem in power consumption. Also, make this switch once a day,
Furthermore, if this switching is performed at midnight or the like where power consumption is low, the dependence on the system is reduced.

In the present invention, in the operation control method of the fuel cell system as described above, the amount of hydrogen produced by the hydrogen producing apparatus is controlled by predicting the output of the next day from the total output of the fuel cell of the previous day. it can. As a result, it is possible to operate continuously from the previous day to the present day, from the present day to the tomorrow, and by controlling the amount of hydrogen produced by the hydrogen producing apparatus for a long period of time in the spring, summer, autumn and winter.

That is, the total power generation amount of the next day is predicted from the total power generation amount of the fuel cell of the previous day, and the total hydrogen amount corresponding to the predicted total power generation amount is produced by making the operation of the membrane reformer constant. Control. That is, the membrane reformer on the next day is controlled so as to always operate at a constant output to produce a total amount of hydrogen corresponding to the expected total power generation amount for the day, and the hydrogen supplied to the fuel cell is a hydrogen storage container. Is supplied according to power demand.

FIG. 8 shows an example of the power consumption over 24 hours measured over time in one day.
For example, the rated output of each device optimal for applying the present fuel cell system to such a power consumption pattern can be determined. That is, in the present invention, since the hydrogen required for the fuel cell (according to the power demand) is supplied from the hydrogen storage container, the maximum hydrogen production amount per unit time of the membrane reformer used is consumed by the fuel cell. The maximum hydrogen consumption per unit time.

For example, the power consumption per day is 15 kW.
h / day. Assuming that the amount of hydrogen required to generate 1 kW of power by the PEFC is 650 L / h, the amount of hydrogen required per day is 650 L × 15 = 9750 L. If this amount of hydrogen is always produced in a constant amount, 9760 ÷ 24 = 406.2 L
/ H. Therefore, the capacity of the hydrogen production apparatus can be 406.7 L / h at maximum. On the other hand, as shown in FIG. 8, the PEFC has a maximum power of 2.8 kW. Therefore, the PEFC having a maximum output of 2.8 kW may be arranged.

As a comparison with the above, in the case of a fuel cell system in which there is no hydrogen storage container which is essential in the present invention and the hydrogen production apparatus and the PEFC are connected one-to-one, the hydrogen production apparatus has a maximum of 650 × 2 .8 = 1,820 L / h of hydrogen production capacity is required, and the hydrogen production apparatus becomes large. Moreover, it is only necessary to produce hydrogen at such a rating for a fraction of a day, most of which must be operated at inefficient partial loads.

On the other hand, according to the present invention, the hydrogen production apparatus and the fuel cell can be set to the optimum, that is, the apparatus having the minimum rated output, and the hydrogen production apparatus can always be continuously operated at the rated power. This allows for very efficient operation,
In addition, since the cost of these devices can be reduced, it is very effective in practical use.

[0043]

According to the present invention, it is possible to operate a fuel cell system comprising a hydrogen producing apparatus and a hydrogen storage container in combination with high efficiency. In addition, various useful effects can be obtained such that the hydrogen production apparatus and the fuel cell can be respectively set to optimal, ie, minimum rated output apparatuses. further,
Since the present invention is an operation method based on pressure, it is very effective also in terms of safety.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a membrane reformer.

FIG. 2 is a diagram showing a mode of production and purification of hydrogen by a membrane reformer.

FIG. 3 is a diagram showing an embodiment of hydrogen purification using a polymer membrane.

FIG. 4 is a diagram showing an example of a high-purity hydrogen production apparatus applied in the present invention.

FIG. 5 is a diagram showing the relationship among the hydrogen production apparatus, each apparatus such as PEFC, hydrogen gas system piping, heat medium system piping, and control electric system piping in the present invention.

FIG. 6 is a diagram illustrating a control mode of the fuel cell system according to the present invention from a stop to a start, a start to a run, and a run to a stop.

FIG. 7 is a diagram illustrating a control mode of the fuel cell system according to the present invention from a stop to a start, a start to a run, and a run to a stop.

FIG. 8 is a graph showing power consumption over 24 hours over a certain day.

[Explanation of symbols]

S, T changeover valve P ₁ to P ₄ for controlling the set pressure

Claims (6)

[Claims] 1. A fuel cell in which hydrocarbons are reformed by a membrane reformer and purified hydrogen is alternately stored and passed through a pair of hydrogen storage containers, and the stored hydrogen is released and supplied to the fuel cell. A method of operating the system,
A method for operating a fuel cell system, comprising: operating a membrane reformer at a constant output, and switching between hydrogen storage and release with the pressure in each hydrogen storage container. 2. A fuel cell in which hydrocarbons are reformed by a membrane reformer and purified hydrogen is alternately inserted and stored in a pair of hydrogen storage containers, and the stored hydrogen is released and supplied to the fuel cell. A method of operating the system,
The membrane reformer is operated at a constant output, and the operation of storing and releasing hydrogen is switched according to the pressure in each hydrogen storage container. At this time, a set pressure P for checking the pressure in the hydrogen storage container at the time of preparation for starting storage is set. ₁ , a set pressure P ₂ for checking the pressure in the hydrogen storage container during storage, a set pressure P ₃ for checking the pressure in the hydrogen storage container at the time of transition to release, and a pressure inside the hydrogen storage container at the time of transition from release to release stop fuel cell to set the set pressure P ₄ that checks the pressure, and carrying out storage of hydrogen in these P ₁ to P ₄ based on the respective hydrogen storage container, the release of hydrogen from the hydrogen storage vessel How the system operates. Wherein said P ₁ to P ₄ respectively P ₁ = 1 atm,
P ₂ = 1 atm, P ₃ = 1.2 atm, P ₄ = 1.2 at
The operating method of the fuel cell system according to claim 2, wherein m is m. 4. The method for operating a fuel cell system according to claim 1, wherein a total power generation amount of the next day is predicted from a total power generation amount of the fuel cell of the previous day, and A method for operating a fuel cell system, characterized in that a corresponding total amount of hydrogen is controlled so as to produce a constant output of the membrane reformer. 5. The method for operating a fuel cell system according to claim 1, wherein the maximum amount of hydrogen produced per unit time of the membrane reformer used is the maximum per unit time consumed by the fuel cell. A method for operating a fuel cell system, wherein the method is smaller than hydrogen consumption. 6. The operating method for a fuel cell system according to claim 1, wherein said fuel cell is a polymer electrolyte fuel cell.