JPH1197052A - Fuel cell power plant and method for switching fuel of it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent modifying performance from being deteriorated by schedule-controlling the flow rate of main fuel and spare fuel so as prevent the ratio S/C of the steam molecule number and the carbon atom number in process gas in an inlet of a catalyst layer of a modifying pipe in a modifying unit from becoming a specified value or less. SOLUTION: In a fuel cell power plant, when fuel is switched and restored from spare fuel to main fuel, the openings of a main fuel flow control valve 15 and a spare fuel flow control valve 16 are controlled by control signals C, D according to a schedule control system for the main fuel and spare fuel flow rates previously input in a controller 13. Therefore, the flow rates of main fuel and spare fuel are so controlled that the S/C ratio in process gas in a catalyst layer inlet in a modifying pipe in a modifying unit 2 may not become a specified value or less, and the S/C ratio in process gas in the catalyst layer inlet in the modifying pipe in the modifying device 2 is prevented from being instantaneously decreased when fuel is switched and restored from spare fuel to main fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous fuel cell system by automatically switching fuel supplied to a fuel cell from a main fuel to a reserve fuel without an instantaneous interruption in an emergency or the like. In a fuel-switched fuel cell power generator that operates stably to supply electric power, especially when the fuel is switched back from the reserve fuel to the main fuel again, the water vapor in the process gas at the catalyst layer inlet in the reforming pipe in the reformer Prevents the ratio of the number of molecules to the number of carbon atoms (hereinafter referred to as the S / C ratio) from dropping sharply, causing carbon deposition of the reforming catalyst, cracking the reforming catalyst, and lowering the reforming performance. The present invention relates to a fuel cell power generator and a fuel switching method thereof.

[0002]

2. Description of the Related Art Conventionally, a fuel cell power generation apparatus reforms a fuel mainly containing methane such as ordinary city gas or LNG into hydrogen gas, and electrochemically converts the hydrogen gas into oxygen in the air with oxygen in the air. It reacts and converts it into electrical energy.

On the other hand, such conventional city gas, LNG
If a fuel cell power plant that uses fuel such as methane as a main component stops the supply of fuel due to a major earthquake or pipe breakage, power generation by this fuel cell power plant will not be possible. There's a problem.

Therefore, recently, in order to continue power generation, a main fuel supply system for automatically supplying a main fuel mainly composed of methane such as city gas or LNG as a main component is used to automatically supply the main fuel. LP convenient for storage different from fuel of supply system
There has been proposed a method of automatically switching to a spare fuel supply system for supplying emergency spare fuel such as G, naphtha, kerosene, etc., and performing a continuous power generation operation of the fuel cell.

[0005] Japanese Patent Application No. 3-95542 and Japanese Patent Application No. 5-22009 disclose a fuel cell power generator having such automatic fuel switching means.
No. 7 "has already been proposed.

FIG. 7 is a schematic diagram showing an example of a system configuration of a fuel cell power generator equipped with this type of conventional automatic fuel switching means. In FIG. 7, a main fuel mainly composed of methane such as ordinary city gas and LNG is mixed with a recycled reformed gas in order to remove a sulfur component in the fuel, heated in a heat exchanger 14 and then a desulfurization device. 1 and mixed with steam to be reformed in a reformer 2 by a reforming catalyst.

[0007] The gas leaving the reformer 2 enters the fuel cell main body 4 after passing through the CO converter 3. The exhaust gas containing hydrogen that has exited the fuel cell body 4 returns to the reformer 2 and burns with a burner to heat the reformer 2.

At this time, the output current of the fuel cell main body 4 detected by the load current detection sensor 61, that is, the load 5 current is input to the controller 13 as a signal a, and the corresponding fuel flow rate and reformed gas recycle flow rate The signal A is sent to the main fuel flow rate control valve 6, the reformed gas recycle flow rate control valve 7, and the reforming steam flow rate control valve 8 so that the reforming steam amount is obtained, and the opening is controlled in a complex manner. .

Whether the temperature of the reformer 2 has reached the set temperature is monitored by a reformer temperature detection sensor 62 and inputted to the controller 13 as a signal b. The opening / closing degree of the main fuel flow control valve 6, reformed gas recycle flow control valve 7, and reforming steam flow control valve 8 is corrected.

The operation of these series of control valves is controlled by the controller 13 as described above so as to be optimal for methane as the main fuel. On the other hand, when the supply of the main fuel normally used is suddenly stopped due to an accident such as an earthquake or a pipe break, the main fuel supply abnormality sensor 91 sends an abnormality signal c to the control device 13 and promptly receives the signal C. First, the main fuel cutoff valve 9 is closed, the reserve fuel cutoff valve 10 is opened by the signal D, and the necessary steam amount of the reserve fuel is calculated based on the data stored in advance by the control device 13 to obtain the reforming steam. The amount of insufficient steam at the opening of the flow rate control valve 8 is determined, the number of the reforming steam bypass shutoff valves to be opened is determined, and the signal E is sent to the reforming steam bypass shutoff valves 11 and 12 (FIG. Although an example in which two steam bypass shutoff valves for reforming are provided in parallel is shown, usually, a large number of valves are used to allow fine flow rate control of the amount of steam.) In this way, switching is made to be optimal for the reserve fuel.

Further, not only the main fuel supply stop signal from the main fuel supply abnormality sensor 91 but also the operator can automatically switch to the reserve fuel by sending a fuel switching signal.

Thus, the operation of the fuel supply system can be continued without any instantaneous interruption under conditions suitable for the reserve fuel. FIG.
FIG. 7 is a schematic diagram showing another example of the system configuration of a fuel cell power generator provided with this kind of conventional automatic fuel switching means, and the same parts as those in FIG. ,
Here, only different parts will be described.

That is, in FIG. 8, a reforming steam bypass flow rate control valve 111 is installed in place of the reforming steam bypass shut-off valves 11 and 12 in FIG. Based on the data, the required steam amount of the reserve fuel is calculated, the amount of insufficient steam at the opening of the reforming steam flow control valve 8 is determined to determine the opening, and the signal F is converted to the reforming steam. Bypass flow control valve 11
1 to switch to an optimal amount of water vapor for the reserve fuel.

By the way, in a fuel cell power generator equipped with such an automatic fuel switching means, when the normally used main fuel stops, the fuel is automatically supplied from the main fuel supply system for automatically supplying the main fuel. Instantaneously switches to the reserve fuel supply system that supplies the reserve fuel for the fuel, and changes the fuel flow rate, reformed gas recycle flow rate, reforming steam amount, and reformer temperature to optimal values for the reserve fuel. After the switching, the power generation operation of the fuel cell is continued.

On the other hand, the calorific value per unit volume differs between a main fuel mainly composed of methane such as city gas and LNG and a spare fuel such as LPG, naphtha and kerosene. For example, a main fuel mainly composed of methane (CH ₄ ) and propane (C
_In the case of a reserve fuel containing ₃ H ₈ ) as the main component, the heat generation per unit volume of the main fuel is about three times higher, and when the fuel is switched from the reserve fuel to the main fuel, the fuel flow rate is reduced. It needs to be increased about three times.

Further, the amount of steam required for reforming differs between the main fuel and the spare fuel. For example, in the case of a main fuel containing methane (CH ₄ ) as a main component and a spare fuel containing propane (C ₃ H ₈ ) as a main component, the main fuel is a catalyst layer inlet in a reforming pipe in the reformer 2. The S / C ratio in the process gas is 2.5 to 4, whereas the S / C ratio of the spare fuel is 4 to 4.5. The fuel flow rate should be about 1 / 1.2-
It needs to be reduced to 1 / 2.0 times.

Accordingly, when the fuel is switched from the main fuel containing methane (CH ₄ ) as the main component to the spare fuel containing propane (C ₃ H ₈ ) as the main component, the main fuel that has been supplied up to that time is switched. It is sufficient to supply a reserve fuel flow rate that is about 1/3 of the fuel flow rate.

For this reason, even if the fuel is switched instantaneously according to, for example, an operation schedule as shown in FIG. 9, S in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 is removed.
The / C ratio tends to be high, and there is no problem that carbon deposition of the reforming catalyst occurs.

[0019]

However, conversely,
When switching fuel from the reserve fuel to the main fuel,
The main fuel flow rate, which is about three times the preliminary fuel flow rate that had been supplied until then, must be supplied. When the fuel is switched instantaneously, the fuel processing system of the fuel cell power generator (from the fuel switching valve to the reformer The desulfurization unit 1, the heat exchanger 14,
And the spare fuel remaining in the piping system during that time) is pushed out at a flow rate that is about three times that of the conventional fuel, and enters the catalyst layer in the reforming pipe in the reformer 2 as it is.

As a result, the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 sharply decreases, carbon deposition of the reforming catalyst occurs, and the reforming catalyst is cracked. There is a problem that the reforming performance is reduced.

Here, the ratio of the main fuel flow rate to the spare fuel flow rate differs depending on the type of the actual main fuel and spare fuel for which fuel switching is performed. An object of the present invention is to provide a fuel supply switchover from the main fuel to the reserve fuel in an emergency or the like, to continue the power generation operation, and then to resume the fuel switch from the reserve fuel to the main fuel again. The S / C ratio in the process gas at the inlet of the catalyst layer in the reforming tube in the reformer sharply decreases, carbon deposition of the reforming catalyst occurs, the reforming catalyst is cracked, and the reforming performance decreases. It is possible to operate the reforming catalyst without deteriorating the reforming catalyst for a long time, and smoothly and reliably perform the fuel switching recovery operation from the spare fuel to the main fuel while maintaining the same operating conditions. It is an object of the present invention to provide a fuel cell power generation device and a fuel switching method thereof.

[0022]

In order to achieve the above object, a main fuel supply system for supplying a main fuel mainly containing methane such as city gas or LNG, and a main fuel supply system different from the main fuel supply system. A fuel supply system comprising an emergency reserve fuel supply system for supplying a reserve fuel such as LPG, naphtha, kerosene, etc., and a fuel reforming system for mixing fuel supplied from the fuel supply system with steam and reforming it into hydrogen gas by a reforming catalyst. Reformer, and a fuel switching method for a fuel switching type fuel cell power generator, comprising: a fuel cell main body that electrochemically reacts hydrogen gas generated in the reformer with oxygen to convert it into electric energy. According to the invention of claim 1, when the fuel is switched from the main fuel to the spare fuel and the power generation operation is continued in an emergency or the like when necessary, when the fuel switching from the spare fuel to the main fuel is restored again, Reforming tube in reformer At least one of the flow rates of the main fuel and the spare fuel or the flow rate of the steam is set so that the ratio (S / C ratio) between the number of water vapor molecules and the number of carbon atoms in the process gas at the inlet of the catalyst layer does not fall below a predetermined value. The schedule is controlled.

Therefore, in the fuel switching method of the fuel switching type fuel cell power generator according to the first aspect of the present invention, the S / C ratio does not fall below a predetermined value when the fuel is switched from the spare fuel to the main fuel again. As described above, at least one of the flow rate of the main fuel and the spare fuel or the flow rate of the steam is schedule-controlled, so that when the fuel is switched again from the spare fuel to the main fuel, the catalyst layer inlet in the reforming pipe in the reformer is restored. , It is possible to prevent the S / C ratio in the process gas from rapidly decreasing.

On the other hand, according to the second aspect of the present invention,
In the fuel switching method for the fuel cell power generator according to the invention of the invention,
As the above-mentioned schedule control, when the fuel is switched from the spare fuel to the main fuel again, the fuel flow rate of the main fuel is maintained for a certain time until the spare fuel remaining in the fuel processing system reaches the reformer. The increase and the decrease in the fuel flow rate of the reserve fuel are performed slowly while monitoring both the fuel flow rates of the main fuel and the reserve fuel.

Therefore, in the fuel switching method for the fuel switching type fuel cell power generator according to the second aspect of the present invention, the S / C ratio does not fall below a certain value when the fuel is switched again from the spare fuel to the main fuel. As described above, by controlling the flow rates of the main fuel and the spare fuel respectively,
When the fuel is switched from the spare fuel to the main fuel again, it is possible to prevent the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer from suddenly decreasing.

According to the third aspect of the present invention, in the first aspect,
In the fuel switching method for the fuel cell power generator according to the invention of the invention,
As the above-mentioned schedule control, when the fuel is switched from the spare fuel to the main fuel again, the fuel flow rate of the spare fuel is set for a certain time until the spare fuel remaining in the fuel processing system reaches the reformer. The fuel flow is gradually reduced, and during this time, the fuel flow rate of the main fuel is made to flow at a flow rate substantially equal to the fuel flow rate of the spare fuel, and then the fuel flow rate of the main fuel is increased to a normal flow rate.

Therefore, according to the fuel switching method of the fuel switching type fuel cell power generator according to the third aspect of the present invention, when the fuel switching from the spare fuel to the main fuel is restored again, the S / C ratio does not fall below a certain specified value. As described above, by controlling the flow rates of the main fuel and the spare fuel respectively,
When the fuel is switched from the spare fuel to the main fuel again, it is possible to prevent the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer from suddenly decreasing.

Further, according to a fourth aspect of the present invention, in the fuel switching method for a fuel cell power generator according to the first aspect of the present invention, as the schedule control, when the fuel switching from the spare fuel to the main fuel is restored again, the fuel processing is performed. For a certain period of time until the spare fuel remaining in the system reaches the reformer, the steam flow rate is almost equal to the flow rate of the spare fuel that has been flowing so far. The steam flow rate is reduced to the fuel flow rate.

Therefore, in the fuel switching method of the fuel switching type fuel cell power generator according to the fourth aspect of the present invention, the S / C ratio does not fall below a predetermined value when the fuel is switched from the spare fuel to the main fuel again. As described above, by controlling the flow rate of the steam, the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer suddenly increases when the fuel is switched from the spare fuel to the main fuel again. It is possible to prevent the lowering.

According to the invention of claim 5, the above-mentioned claim 1 is provided.
In the fuel switching method for the fuel cell power generator according to the invention of the invention,
As the above-mentioned schedule control, when the fuel is switched from the spare fuel to the main fuel again, the fuel flow rate of the main fuel is maintained for a certain time until the spare fuel remaining in the fuel processing system reaches the reformer. While increasing and decreasing the fuel flow rate of the reserve fuel while monitoring both the fuel flow rates of the main fuel and the reserve fuel, the fuel flow rate of the reserve fuel was gradually reduced, and the steam flow rate had been flowing until now. After flowing a flow rate substantially equal to the flow rate corresponding to the reserve fuel, the flow rate is reduced to a steam flow rate corresponding to the fuel flow rate of the main fuel.

Therefore, in the fuel switching method for a fuel switching type fuel cell power generator according to the fifth aspect of the present invention, the S / C ratio does not fall below a certain value when the fuel switching from the spare fuel to the main fuel is restored again. As described above, by controlling the flow rates of the main fuel and the spare fuel, and the flow rate of the steam, respectively, when the fuel is switched from the spare fuel to the main fuel again, the process at the catalyst layer inlet in the reforming pipe in the reformer is performed. It is possible to prevent the S / C ratio in the gas from suddenly decreasing.

Further, according to a sixth aspect of the present invention, in the fuel switching method for a fuel cell power generator according to the first aspect of the present invention, as the schedule control, when the fuel switching from the spare fuel to the main fuel is restored again, the fuel processing is performed. The fuel flow of the reserve fuel is gradually reduced for a certain period of time until the reserve fuel remaining in the system reaches the reformer, during which the fuel flow of the main fuel is substantially equal to the fuel flow of the reserve fuel. After flowing the flow rate, the fuel flow rate of the main fuel is increased to a regular flow rate, and is decreased to a steam flow rate corresponding to the fuel flow rate of the main fuel.

Therefore, according to the fuel switching method of the fuel switching type fuel cell power generator of the invention of claim 6, when the fuel switching from the spare fuel to the main fuel is restored again, the S / C ratio does not fall below a certain value. As described above, by controlling the flow rates of the main fuel and the spare fuel, and the flow rate of the steam, respectively, when the fuel is switched from the spare fuel to the main fuel again, the process at the catalyst layer inlet in the reforming pipe in the reformer is performed. It is possible to prevent the S / C ratio in the gas from suddenly decreasing.

On the other hand, in the fuel cell power generator according to the present invention, a main fuel supply system for supplying a main fuel mainly composed of methane such as city gas and LNG, and an LPG different from the main fuel of the main fuel supply system. A fuel supply system consisting of an emergency reserve fuel supply system that supplies reserve fuel such as fuel, naphtha, kerosene, etc., and reforming in which fuel supplied from the fuel supply system is mixed with steam and reformed into hydrogen gas by a reforming catalyst. A fuel cell that converts the hydrogen gas generated in the reformer to oxygen by electrochemical reaction with oxygen, and a fuel switch from the main fuel to the reserve fuel when an emergency is required. And the fuel switching function to continue the power generation operation, and when the fuel is switched from the spare fuel to the main fuel again after the fuel switching, the number of water vapor molecules and carbon in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer atom Fuel switching means having a schedule control function of controlling at least one of the flow rates of the main fuel and the spare fuel or the flow rate of the steam so that the ratio (S / C ratio) does not fall below a predetermined value. I have.

Therefore, in the fuel cell power generator according to the seventh aspect of the present invention, when the fuel is switched again from the reserve fuel to the main fuel, the main fuel and the reserve fuel are controlled so that the S / C ratio does not fall below a specified value. At least one of the flow rate of the fuel and the flow rate of the steam is schedule-controlled by the fuel switching means, so that when the fuel is switched again from the spare fuel to the main fuel, the process at the catalyst layer inlet in the reforming pipe in the reformer is performed. It is possible to prevent the S / C ratio in the gas from suddenly decreasing.

As described above, when the fuel is switched from the spare fuel to the main fuel again, carbon deposition of the reforming catalyst occurs, and the reforming catalyst is prevented from being cracked and the reforming performance can be prevented from lowering. The reforming catalyst can be operated without deterioration for a long time. Moreover, it is possible to smoothly and reliably perform the fuel switching recovery operation from the spare fuel to the main fuel while maintaining the same operating conditions.

[0037]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) (Corresponding to Claims 1 and 7) FIG. 1 is a schematic diagram showing an example of a system configuration of a fuel cell power generator according to the present embodiment. The description is omitted by attaching the reference numerals, and only different portions will be described here.

That is, as shown in FIG. 1, the fuel cell power generator of the present embodiment has a main fuel cutoff valve 9 shown in FIG.
In addition to installing the main fuel flow control valve 15 and the preliminary fuel flow control valve 16 in place of the preliminary fuel cutoff valve 10,
Instead of the reforming steam flow control valve 8, a steam flow control valve 17
And before the main fuel flow control valve 6, the main fuel,
A fuel gas detector 18 capable of detecting the ratio of the reserve fuel is provided, and an output signal from the fuel gas detector 18 is input to the control device 13.

Further, the controller 13 switches the fuel from the main fuel to the spare fuel to continue the power generation operation when necessary in an emergency or the like, and resumes the fuel switching from the spare fuel to the main fuel again. At this time, at least the flow rates of the main fuel and the spare fuel or the flow rates of the steam are set so that the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming tube in the reformer 2 does not suddenly fall below a certain specified value. It has a fuel switching function in which one is controlled by a schedule control system.

Here, as a function of the schedule control system, when the fuel is switched from the reserve fuel to the main fuel again, the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 is reduced. There is a function to control the opening of the main fuel flow control valve 15 and the reserve fuel flow control valve 16 and a function to control the opening of the steam flow control valve 17 so as not to be lower than a certain specified value. .

As a function of controlling the opening degree of the main fuel flow control valve 15 and the reserve fuel flow control valve 16, a schedule control system of the main fuel flow and the reserve fuel flow is input to the control device 13 in advance. A function of controlling the opening degrees of the main fuel flow control valve 15 and the spare fuel flow control valve 16 in accordance with the control signals C and D from the control device 13 accordingly,
Alternatively, an output signal from the fuel gas detector 18 is input to the control device 13, and the main fuel flow control valve 15, the reserve fuel flow There is a function of controlling the opening of the control valve 16 by control signals C and D from the control device 13.

On the other hand, the function of controlling the opening of the steam flow control valve 17 is to input a schedule control system for the steam flow to the control device 13 in advance, and to control the opening of the steam flow control valve 17 accordingly. A function controlled by the control signal F from the control unit 13 or an output signal from the fuel gas detector 18 is input to the control unit 13, and the steam flow rate corresponding to the ratio of the main fuel and the reserve fuel previously input to the control unit 13. Has the function of controlling the opening degree of the steam flow control valve 17 by the control signal F from the control device 13 in accordance with the schedule control system of the above.

Next, a description will be given of a fuel switching method in the fuel cell power generator of the present embodiment configured as described above. The description of the same parts as those in the fuel switching method in the conventional fuel cell power generator shown in FIGS. 7 and 8 is omitted, and only different parts are described here.

That is, in the fuel cell power generator shown in FIG. 1, when the fuel is switched again from the spare fuel to the main fuel, the schedule control of the main fuel flow rate and the spare fuel flow rate previously input to the controller 13 is performed. Depending on the system, the opening degree of the main fuel flow control valve 15 and the reserve fuel flow control valve 16 is controlled by control signals C and D, or input to the control device 13 in advance based on the output signal from the fuel gas detector 18. The opening degrees of the main fuel flow control valve 15 and the reserve fuel flow control valve 16 are controlled by the control signals C and D according to the schedule control system for the ratio of the main fuel and the reserve fuel.

Thus, the flow rates of the main fuel and the spare fuel are controlled so that the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 does not fall below a specified value. When the fuel is switched from the spare fuel to the main fuel, the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 can be prevented from being sharply reduced.

On the other hand, according to the schedule control system for the steam flow rate which is input to the control device 13 in advance, the opening of the steam flow rate control valve 17 is controlled by the control signal F or the output signal from the fuel gas detector 18 is controlled. Based on the schedule control system of the steam flow rate corresponding to the ratio of the main fuel and the spare fuel previously input to the control device 13,
The opening of the steam flow control valve 17 is controlled by the control signal F.

Thus, the flow rate of the steam is controlled so that the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 does not become lower than a predetermined value, and the main fuel is returned from the spare fuel again. When the fuel is switched back to the fuel, the S / C in the process gas at the catalyst layer inlet in the reforming pipe in the reformer 2
It is possible to prevent the ratio from dropping sharply.

As described above, in the present embodiment, when an emergency or the like is necessary, the fuel is switched from the main fuel to the spare fuel to continue the power generation operation, and then the spare fuel is switched to the main fuel again. When the fuel switching is restored, the flow rates of the main fuel and the spare fuel or the flow rates of the steam are set so that the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 does not become lower than a predetermined value. The schedule control of at least one of the two is performed, so that when the fuel is switched from the reserve fuel to the main fuel and restored, the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 sharply increases. It is possible to prevent the lowering.

Thus, when the fuel is switched again from the spare fuel to the main fuel, the carbon deposition of the reforming catalyst occurs as described above, thereby preventing the reforming catalyst from cracking and lowering the reforming performance. Therefore, the reforming catalyst can be operated without deteriorating the reforming catalyst for a long time, and the stable operation of the fuel cell power generator can be continued even after the fuel switch from the spare fuel to the main fuel is restored.

In addition, when the fuel is switched from the spare fuel to the main fuel again, the fuel is automatically switched from the spare fuel to the main fuel. Therefore, the spare fuel can be smoothly and reliably maintained under the same operating conditions. The fuel can be switched to the main fuel and the recovery operation can be performed.

(Second Embodiment) (corresponding to claim 2) In the fuel cell power generator of the present embodiment, the backup control is again performed as a function of the schedule control system in the fuel cell power generator of the first embodiment. When the fuel is switched from the fuel to the main fuel and restored, the fuel flow rate of the main fuel is increased, and the amount of the spare fuel is increased for a certain period of time until the spare fuel remaining in the fuel processing system reaches the reformer 2. A function of gently reducing the fuel flow rate while monitoring both the fuel flow rates of the main fuel and the spare fuel is provided.

Next, a fuel switching method in the fuel cell power generator of the present embodiment configured as described above will be described.
This will be described with reference to FIG. 7 and 8 described above.
The description of the same parts as those of the conventional fuel cell power generator shown in FIG. 1 is omitted, and only different parts will be described here.

FIG. 2 is a diagram showing an example of an operation schedule when the fuel is switched from the reserve fuel to the main fuel in the fuel cell power generator according to the present embodiment, and the horizontal axis represents time,
The vertical axis shows the fuel flow rate.

That is, in the fuel cell power generator shown in FIG. 1, when the fuel is switched again from the spare fuel to the main fuel, the fuel processing system (from the spare fuel control valve 16 in FIG. For a certain period of time until the spare fuel remaining in the desulfurization apparatus 1, the heat exchanger 14, and the piping system therebetween reaches the catalyst layer in the reforming pipe in the reformer 2.
(A) The fuel flow rate of the main fuel is increased, and (B) The fuel flow rate of the reserve fuel is gradually reduced while monitoring both fuel flow rates.

Here, the certain time in FIG. 2 is a certain time until the spare fuel remaining in the fuel processing system reaches the catalyst layer in the reforming pipe in the reformer. The volume of the residual gas is calculated in advance, and is controlled by the control device 13 in FIG. 1 so that the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming tube in the reformer 2 does not fall below a predetermined value. Control.

As described above, the main fuel flow required for power generation by the fuel cell power generator is about two to three times the reserve fuel flow, and if the main fuel flow required for fuel switching recovery is suddenly added. The spare fuel remaining in the fuel processing system is pushed out by the main fuel and immediately reaches the catalyst layer in the reforming pipe in the reformer 2, and the catalyst layer in the reforming pipe in the reformer 2 There is a problem that the S / C ratio at the entrance is rapidly reduced.

In this regard, as in the present embodiment, the increase in the fuel flow rate of the main fuel and the decrease in the fuel flow rate of the reserve fuel are performed gently while monitoring the flow rates of both fuels. It is possible to prevent the S / C ratio at the catalyst layer inlet in the reforming tube from falling below a certain specified value.

That is, the main fuel flow control valve 15 shown in FIG.
By controlling the opening degree of the reserve fuel flow control valve 16 in accordance with FIG. 2, the reserve fuel remaining in the fuel processing system is rapidly pushed out by the main fuel, and the catalyst layer in the reforming pipe in the reformer 2 is removed. When the S / C ratio at the inlet sharply decreases, carbon deposition of the reforming catalyst occurs, and it is possible to prevent the reforming catalyst from cracking and lowering the reforming performance.

As described above, in the present embodiment, when an emergency or the like is necessary, the fuel is switched from the main fuel to the spare fuel to continue the power generation operation, and then the spare fuel is switched to the main fuel again. When the fuel switching is restored, the fuel flow of the main fuel is increased and the fuel flow of the spare fuel is decreased for a certain time until the spare fuel remaining in the fuel processing system reaches the reformer 2. When the fuel is switched from the spare fuel to the main fuel and the fuel is restored, the process at the inlet of the catalyst layer in the reforming pipe in the reformer 2 is performed. It is possible to prevent the S / C ratio in the gas from suddenly decreasing.

Thus, when the fuel is switched back from the spare fuel to the main fuel again, carbon deposition of the reforming catalyst occurs as described above, thereby preventing the reforming catalyst from cracking and lowering the reforming performance. Therefore, the reforming catalyst can be operated without deteriorating the reforming catalyst for a long time, and the stable operation of the fuel cell power generator can be continued even after the fuel switch from the spare fuel to the main fuel is restored.

In addition, when the fuel is switched from the spare fuel to the main fuel again, the fuel is automatically switched from the spare fuel to the main fuel, so that the spare fuel can be smoothly and reliably maintained under the same operating conditions. The fuel can be switched to the main fuel and the recovery operation can be performed.

(Third Embodiment) (corresponding to claim 3) In the fuel cell power generator according to the present embodiment, the standby control is again performed as a function of the schedule control system in the fuel cell power generator according to the first embodiment. When the fuel is switched from the fuel to the main fuel and restored, the fuel flow rate of the spare fuel is gradually reduced for a certain time until the spare fuel remaining in the fuel processing system reaches the reformer 2. A function of increasing the fuel flow rate of the main fuel to a normal flow rate after flowing the fuel flow rate of the main fuel at a flow rate substantially equal to the fuel flow rate of the reserve fuel is provided.

Next, a fuel switching method in the fuel cell power generator of the present embodiment configured as described above will be described.
This will be described with reference to FIG. 7 and 8 described above.
The description of the same parts as those of the conventional fuel cell power generator shown in FIG. 1 is omitted, and only different parts will be described here.

FIG. 3 is a diagram showing an example of an operation schedule when the fuel is switched from the reserve fuel to the main fuel in the fuel cell power generator according to the present embodiment, and the horizontal axis represents time, and the vertical axis represents the fuel flow rate. Are respectively shown.

That is, in the fuel cell power generator shown in FIG. 1, when the fuel is switched from the spare fuel to the main fuel again, the spare fuel remaining in the fuel processing system is replaced with the spare fuel in the reformer 2. The fuel flow rate of (B) the reserve fuel is gradually reduced for a certain period of time until it reaches the in-pipe catalyst layer, during which the fuel flow rate of (A) the main fuel is substantially equal to the fuel flow rate of (B) the reserve fuel After a certain amount of flow, the fuel flow rate of the main fuel is increased to a normal flow rate.

That is, when the operation is performed according to the operation schedule of the present embodiment, unlike the case of FIG. 2 described above, immediately after the restoration of the fuel switching, the fuel flow of the main fuel is changed to the fuel flow of the spare fuel that has been flowing until then. Since a timer function is provided for the fuel flow rate of the main fuel for a fixed time so that a substantially equal flow rate flows for a certain time, the controller 13 in FIG.
The increase in the fuel flow rate of the main fuel and the decrease in the fuel flow rate of the reserve fuel do not require any special control while monitoring both fuel flow rates. It is possible to prevent the S / C ratio from falling below a certain specified value.

As described above, in the present embodiment, when an emergency or the like is necessary, the fuel is switched from the main fuel to the spare fuel to continue the power generation operation, and then the spare fuel is switched to the main fuel again. When the fuel switching is restored, the fuel flow rate of the spare fuel is gradually reduced for a certain period of time until the spare fuel remaining in the fuel processing system reaches the reformer 2, and the fuel flow rate of the main fuel during that time is reduced. After the fuel flow rate is almost equal to the fuel flow rate of the spare fuel, the fuel flow rate of the main fuel is increased to the normal flow rate. 2, it is possible to prevent the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming tube from being rapidly lowered.

As a result, when the fuel is switched again from the spare fuel to the main fuel, the carbon deposition of the reforming catalyst occurs as described above, and the reforming catalyst is prevented from cracking and the reforming performance is prevented from deteriorating. Therefore, the reforming catalyst can be operated without deteriorating the reforming catalyst for a long time, and the stable operation of the fuel cell power generator can be continued even after the fuel switch from the spare fuel to the main fuel is restored.

In addition, when the fuel is switched from the spare fuel to the main fuel again, the fuel is automatically switched from the spare fuel to the main fuel. Therefore, the spare fuel can be smoothly and reliably maintained under the same operating conditions. The fuel can be switched to the main fuel and the recovery operation can be performed.

Immediately after the restoration of the fuel switching, the main fuel flow rate is set to a constant time by a timer function so that the main fuel flow rate is equal to the spare fuel flow rate that has been flowing until then. Because of this, it is not necessary to perform special control while monitoring both fuel flows to increase the fuel flow rate of the main fuel and decrease the fuel flow rate of the reserve fuel.

(Fourth Embodiment) (Corresponding to Claim 4) In the fuel cell power generation device of the present embodiment, the function of the schedule control system in the fuel cell power generation device of the first embodiment is again used as a spare. When the fuel is switched from the fuel to the main fuel and the fuel is restored, the steam flow for the predetermined time until the spare fuel remaining in the fuel processing system reaches the reformer 2 matches the spare fuel that has been flowing. After the flow rate is substantially equal to the flow rate of the main fuel, the flow rate is reduced to a steam flow rate corresponding to the fuel flow rate of the main fuel.

Next, a fuel switching method in the fuel cell power generator of the present embodiment configured as described above will be described.
This will be described with reference to FIG. 7 and 8 described above.
The description of the same parts as those of the conventional fuel cell power generator shown in FIG. 1 is omitted, and only different parts will be described here.

FIG. 4 is a diagram showing an example of an operation schedule when the fuel is switched from the reserve fuel to the main fuel in the fuel cell power generator according to the present embodiment, and the time is plotted on the horizontal axis and the steam flow rate is plotted on the vertical axis. Are respectively shown.

That is, in the fuel cell power generator shown in FIG. 1, when the fuel is switched from the spare fuel to the main fuel again and restored, the spare fuel remaining in the fuel processing system is converted into the fuel in the reformer 2. The output signal from the fuel gas detector 18 is sent to the control device 13 for a certain period of time until it reaches the catalyst layer in the gas tube.
The opening of the steam flow control valve 17 is controlled by the control signal F from the control device 13 in accordance with the schedule control system of the steam flow corresponding to the ratio of the main fuel and the spare fuel which has been input to the control device 13 in advance. I do.

In this case, as shown, actually,
The steam flow rate will be gradually reduced to a flow rate that is almost equal to the flow rate corresponding to the reserve fuel that was flowing before the fuel switchover restoration, or to a steam flow rate that matches the fuel flow rate of the main fuel after flowing a little more. .

That is, when the operation is performed according to the operation schedule of the present embodiment, unlike the case of FIGS. 2 and 3, the steam flow control valve 1
7, so that the opening control of the main fuel flow control valve 15 and the spare fuel flow control valve 16 is not performed.
The S / C ratio in the process gas at the inlet of the catalyst layer in the reforming tube in the reformer 2 can be prevented from falling below a certain specified value.

As described above, in the present embodiment, when an emergency or the like is necessary, the fuel is switched from the main fuel to the spare fuel to continue the power generation operation, and then the spare fuel is switched to the main fuel again. When the fuel switching is restored, the steam flow rate during the certain time until the spare fuel remaining in the fuel processing system reaches the reformer 2 is substantially equal to the flow rate corresponding to the spare fuel that has been flowing so far. After the flow rate of the main fuel is reduced, the flow rate is reduced to the steam flow rate corresponding to the fuel flow rate of the main fuel. It is possible to prevent the S / C ratio in the process gas at the inlet from suddenly lowering.

As a result, when the fuel is switched from the spare fuel to the main fuel again, carbon deposition of the reforming catalyst occurs as described above, and the reforming catalyst is prevented from being cracked and the reforming performance from being reduced. Therefore, the reforming catalyst can be operated without deteriorating the reforming catalyst for a long time, and the stable operation of the fuel cell power generator can be continued even after the fuel switch from the spare fuel to the main fuel is restored.

Further, when the fuel is switched from the spare fuel to the main fuel again, the fuel is automatically switched from the spare fuel to the main fuel. Therefore, the spare fuel can be smoothly and reliably maintained under the same operating conditions. The fuel can be switched to the main fuel and the recovery operation can be performed.

(Fifth Embodiment) (corresponding to claim 5) In the fuel cell power generator according to the present embodiment, the function of the schedule control system in the fuel cell power generator according to the first embodiment is again used as a spare. When the fuel is switched from the fuel to the main fuel and restored, the fuel flow rate of the main fuel is increased, and the amount of the spare fuel is increased for a certain period of time until the spare fuel remaining in the fuel processing system reaches the reformer 2. The fuel flow rate is gradually reduced while monitoring both the main fuel and the reserve fuel flow rates, and the reserve fuel flow rate is gradually reduced while the steam flow rate matches the reserve fuel that has been flowing. After the flow rate is approximately the same as that of the main fuel, the function of reducing the steam flow rate to the fuel flow rate of the main fuel is provided.

Next, a fuel switching method in the fuel cell power generator of the present embodiment configured as described above will be described.
This will be described with reference to FIG. 7 and 8 described above.
The description of the same parts as those of the second and fourth embodiments shown in FIGS. 2 and 4 will be omitted, and only different parts will be described here.

FIG. 5 is a diagram showing an example of an operation schedule for simultaneously controlling the fuel flow rate and the steam flow rate when the fuel is switched from the reserve fuel to the main fuel and is restored in the fuel cell power generator according to the present embodiment. The horizontal axis shows time, the upper part of the vertical axis shows the fuel flow rate, and the lower part of the vertical axis shows the steam flow rate.

That is, when operating according to the operation schedule of this embodiment, the operation schedule of the fuel flow rate in the second embodiment shown in FIG.
And the operation schedule of the steam flow rate in the fourth embodiment shown in FIG. 4 is simultaneously performed. In the same manner as described above, the S / S The C ratio can be prevented from falling below a certain specified value.

In this case, the change in the fuel flow rate and the change in the steam flow rate when the fuel is switched from the reserve fuel to the main fuel again is determined by controlling the fuel flow rate alone or the steam flow rate as described above. The width of each flow rate variation is smaller than in the case where the main fuel flow control valve 1 shown in FIG.
5, spare fuel flow control valve 16, and steam flow control valve 1
7, the opening width of each flow control valve 1 can be reduced.
5, 16, and 17 can be miniaturized.

Incidentally, for example, the fuel is simply changed from the spare fuel (propane (C ₃ H ₈ ) (S / C = 4.0)) to the main fuel (ethane (CH ₄ ) (S / C = 3.0)). When switching and restoring, assuming that the spare fuel flow rate is Gy and the main fuel flow rate is Gs, the change in the required steam flow rate Gn during the process of restoring the fuel switching from the spare fuel to the main fuel is expressed by the following equation. be able to.

Required steam flow rate Gn = Gy × 3 × 4.0 + Gs × 3.0 In this case, as a method of controlling the steam flow rate, for example, the opening degree control of the steam flow rate control valve 17 in FIG. Enter the schedule control system for the steam flow rate,
According to the method, the steam flow control valve 17 is controlled by the control signal F, or the output signal from the fuel gas detector 18 is input to the control device 13 and the main fuel and the reserve There is a method in which the opening degree of the steam flow control valve 17 is controlled by a control signal F from the control device 13 according to a schedule control system of the steam flow corresponding to the ratio with the fuel.

As described above, in the present embodiment, when an emergency or the like is necessary, the fuel is switched from the main fuel to the spare fuel to continue the power generation operation, and then the spare fuel is switched to the main fuel again. When the fuel switching is restored, the fuel flow of the main fuel is increased and the fuel flow of the spare fuel is decreased for a certain time until the spare fuel remaining in the fuel processing system reaches the reformer 2. , While monitoring both fuel flow of the main fuel and the spare fuel, gradually reduce the fuel flow of the spare fuel, and at the same time, reduce the steam flow rate to a flow rate almost equivalent to the flow rate of the spare fuel that has been flowing until now. After flowing the fuel, the flow rate is reduced to a steam flow rate commensurate with the fuel flow rate of the main fuel. In process gas S / C ratio can be prevented from being suddenly reduced.

As a result, when the fuel is switched from the spare fuel to the main fuel again, the carbon deposition of the reforming catalyst occurs as described above, and the reforming catalyst is prevented from cracking and the reforming performance is prevented from deteriorating. Therefore, the reforming catalyst can be operated without deteriorating the reforming catalyst for a long time, and the stable operation of the fuel cell power generator can be continued even after the fuel switch from the spare fuel to the main fuel is restored.

In addition, when the fuel is switched from the spare fuel to the main fuel again, the fuel is automatically switched from the spare fuel to the main fuel. Therefore, the spare fuel can be smoothly and reliably maintained under the same operating conditions. The fuel can be switched to the main fuel and the recovery operation can be performed.

Further, the change in the fuel flow rate and the steam flow rate when the fuel is switched from the spare fuel to the main fuel again is compared with the case where the fuel flow rate or the steam flow rate is independently controlled. Because the range of fluctuation is small,
By reducing the opening width of the main fuel flow control valve 15, the spare fuel flow control valve 16, and the steam flow control valve 17, it is possible to reduce the size of each of the flow control valves 15, 16, and 17.

(Sixth Embodiment) (Corresponding to Claim 6) In the fuel cell power generation device of the present embodiment, the function of the schedule control system in the fuel cell power generation device of the first embodiment is again used as a spare. When the fuel is switched from the fuel to the main fuel and restored, the fuel flow rate of the spare fuel is gradually reduced for a certain time until the spare fuel remaining in the fuel processing system reaches the reformer 2. After flowing the fuel flow rate of the main fuel approximately equal to the fuel flow rate of the spare fuel, the function to increase the fuel flow rate of the main fuel to the regular flow rate and to reduce the steam flow rate to the fuel flow rate of the main fuel. I have it.

Next, a fuel switching method in the fuel cell power generator of the present embodiment configured as described above will be described.
This will be described with reference to FIG. 7 and 8 described above.
The description of the same parts as those of the second and fourth embodiments shown in FIGS. 3 and 4 will be omitted, and only different parts will be described here.

FIG. 6 is a diagram showing another example of an operation schedule for simultaneously controlling the fuel flow rate and the steam flow rate in the fuel cell power generator according to the present embodiment when the fuel is switched from the spare fuel to the main fuel and restored. The horizontal axis indicates time, the vertical axis indicates the fuel flow rate, and the vertical axis indicates the steam flow rate.

That is, when the operation is performed according to the operation schedule of this embodiment, the operation schedule of the fuel flow rate in the third embodiment shown in FIG.
And the operation schedule of the steam flow rate in the fourth embodiment shown in FIG. 4 is simultaneously performed. In the same manner as described above, the S / S The C ratio can be prevented from falling below a certain specified value.

In this case, the change in the fuel flow rate and the change in the steam flow rate when the fuel is switched from the spare fuel to the main fuel again is determined by controlling the fuel flow rate alone or the steam flow rate as described above. The width of each flow rate variation is smaller than in the case where the main fuel flow control valve 1 shown in FIG.
5, spare fuel flow control valve 16, and steam flow control valve 1
7, the opening width of each flow control valve 1 can be reduced.
5, 16, and 17 can be miniaturized.

Further, in this case, immediately after the fuel switching is restored, the fuel flow rate of the main fuel is changed so that the fuel flow rate of the main fuel flows at a flow rate substantially equal to the fuel flow rate of the spare fuel which has been flowing so far for a certain time. Since a timer function is provided for a fixed period of time, it is necessary to perform special control of the increase in the fuel flow rate of the main fuel and the decrease in the fuel flow rate of the reserve fuel by monitoring both fuel flow rates in the control device 13 of FIG. And the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming tube in the reformer 2 is
It can be ensured that it does not fall below a certain specified value.

As described above, in the present embodiment, when an emergency or the like is necessary, the fuel is switched from the main fuel to the spare fuel to continue the power generation operation, and then the spare fuel is switched to the main fuel again. When the fuel switching is restored, the fuel flow rate of the spare fuel is gradually reduced for a certain period of time until the spare fuel remaining in the fuel processing system reaches the reformer 2, and the fuel flow rate of the main fuel during that time is reduced. After flowing a flow rate substantially equal to the fuel flow rate of the reserve fuel, the fuel flow rate of the main fuel is increased to a regular flow rate and the steam flow rate is reduced to a steam flow rate corresponding to the fuel flow rate of the main fuel. When the fuel is switched back from the fuel to the main fuel, it is possible to prevent the S / C ratio in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer 2 from suddenly decreasing.

As a result, when the fuel is switched from the spare fuel to the main fuel again, carbon deposition of the reforming catalyst occurs as described above, and the reforming catalyst is prevented from cracking and the reforming performance is prevented from deteriorating. Therefore, the reforming catalyst can be operated without deteriorating the reforming catalyst for a long time, and the stable operation of the fuel cell power generator can be continued even after the fuel switch from the spare fuel to the main fuel is restored.

Further, when the fuel is switched from the spare fuel to the main fuel again, the fuel is automatically switched from the spare fuel to the main fuel. Therefore, the spare fuel can be smoothly and reliably maintained under the same operating conditions. The fuel can be switched to the main fuel and the recovery operation can be performed.

Further, the change in the fuel flow rate and the steam flow rate when the fuel is switched from the spare fuel to the main fuel again is compared with the case where the fuel flow rate or the steam flow rate is independently controlled. Because the range of fluctuation is small,
By reducing the opening width of the main fuel flow control valve 15, the spare fuel flow control valve 16, and the steam flow control valve 17, it is possible to reduce the size of each of the flow control valves 15, 16, and 17.

Further, immediately after the fuel switching is restored, the main fuel flow rate is set to a constant time timer function so that the main fuel flow rate is substantially the same as the spare fuel flow rate that has been flowing until then. Because of this, it is not necessary to perform special control while monitoring both fuel flows to increase the fuel flow rate of the main fuel and decrease the fuel flow rate of the reserve fuel.

[0102]

As described above, according to the fuel cell power generation apparatus and the fuel switching method of the present invention, when the fuel switching from the spare fuel to the main fuel is restored again, the S / C ratio is equal to or less than a predetermined value. At least one of the flow rate of the main fuel and the spare fuel or the flow rate of the steam is controlled so as not to cause the situation, so when the fuel is switched from the spare fuel to the main fuel and restored, the reforming in the reformer is performed. It is possible to prevent the S / C ratio in the process gas at the inlet of the in-tube catalyst layer from suddenly decreasing.

Thus, when the fuel is switched from the spare fuel to the main fuel again, carbon deposition of the reforming catalyst occurs, which prevents the reforming catalyst from cracking and lowering the reforming performance. The operation can be performed without deteriorating the reforming catalyst for a long time, and the stable operation of the fuel cell power generator can be continued even after the fuel switch from the spare fuel to the main fuel is restored.

In addition, when the fuel is switched from the spare fuel to the main fuel again, the fuel is automatically switched from the spare fuel to the main fuel. Therefore, the spare fuel can be smoothly and reliably maintained under the same operating conditions. The fuel can be switched to the main fuel and the recovery operation can be performed.

Immediately after the restoration of the fuel switching, the main fuel flow rate is set to a fixed time by a timer function so that the main fuel flow rate is equal to the spare fuel flow rate that has been flowing so far. Because I have to have
It is not necessary to perform any special control while monitoring both fuel flow rates to increase the fuel flow rate of the main fuel and decrease the fuel flow rate of the reserve fuel.

Further, the changes in the fuel flow rate and the steam flow rate when the fuel is switched from the spare fuel to the main fuel again and restored are as follows.
Since the independent control of the fuel flow rate and the independent control of the steam flow rate are simultaneously performed, the fluctuation width of each flow rate is reduced, and the opening width of each flow control valve can be reduced. The size of the flow control valve can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of a fuel cell power generator and a fuel switching method thereof according to the present invention.

FIG. 2 is an operation schedule diagram showing a second embodiment of the fuel switching method for the fuel cell power generator according to the present invention.

FIG. 3 is an operation schedule diagram illustrating a third embodiment of a fuel switching method for a fuel cell power generator according to the present invention.

FIG. 4 is an operation schedule diagram showing a fourth embodiment of the fuel switching method for the fuel cell power generator according to the present invention.

FIG. 5 is an operation schedule diagram showing a fifth embodiment of the fuel switching method for the fuel cell power generator according to the present invention.

FIG. 6 is an operation schedule diagram showing a sixth embodiment of the fuel switching method for the fuel cell power generator according to the present invention.

FIG. 7 is a schematic diagram showing an example of a system configuration of a conventional fuel cell power generator provided with automatic fuel switching means.

FIG. 8 is a schematic diagram showing another example of the system configuration of a conventional fuel cell power generator provided with automatic fuel switching means.

FIG. 9 is a diagram showing an example of an operation schedule when fuel switching from main fuel to spare fuel is restored in a conventional fuel cell power generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Desulfurization apparatus, 2 ... Reformer, 3 ... CO converter, 4 ... Fuel cell main body, 5 ... Load, 6 ... Main fuel flow control valve, 7 ... Reformed gas recycle flow control valve, 8 ... Reforming Steam flow control valve, 9: main fuel cutoff valve, 10: spare fuel cutoff valve, 11: reforming steam bypass shutoff valve, 12: reforming steam bypass shutoff valve, 13: control device, 14: heat exchanger, 15: Main fuel flow control valve, 16: Reserve fuel flow control valve, 17: Steam flow control valve, 18: Fuel gas detector, 61: Load current detection sensor, 62: Reformer temperature detection sensor, 91: Main fuel Supply abnormality sensor, 111: steam bypass flow rate control valve for reforming.

Claims (7)

[Claims] 1. A main fuel supply system for supplying a main fuel mainly composed of methane such as city gas and LNG, and a spare fuel such as LPG, naphtha, kerosene and the like different from the main fuel of the main fuel supply system. A fuel supply system comprising an emergency reserve fuel supply system, a reformer for mixing fuel supplied from the fuel supply system with steam, and reforming the mixture into hydrogen gas with a reforming catalyst; In a fuel switching method for a fuel-switching fuel cell power generator, comprising: a fuel cell body that electrochemically reacts hydrogen gas with oxygen to convert the hydrogen gas into electric energy. After the fuel is switched from the main fuel to the spare fuel and the power generation operation is continued, when the fuel is switched again from the spare fuel to the main fuel, the process gas at the catalyst layer inlet in the reforming pipe in the reformer is restored. Water vapor Schedule control of at least one of the flow rates of the main fuel and the spare fuel or the flow rate of the steam so that the ratio of the number of carbon atoms to the number of carbon atoms (S / C ratio) does not fall below a predetermined value. A fuel switching method for a fuel cell power generator, comprising: 2. The fuel switching method for a fuel cell power generator according to claim 1, wherein the schedule control is performed such that when the fuel is switched from the spare fuel to the main fuel again, the fuel remains in the fuel processing system. For a certain period of time until the spare fuel reaches the reformer,
An increase in the fuel flow rate of the main fuel and a decrease in the fuel flow rate of the spare fuel while monitoring both the fuel flow rates of the main fuel and the spare fuel. Fuel switching method. 3. The fuel switching method for a fuel cell power generator according to claim 1, wherein the schedule control includes the step of remaining in the fuel processing system when the fuel switching from the reserve fuel to the main fuel is resumed. For a certain period of time until the spare fuel reaches the reformer,
After gradually decreasing the fuel flow rate of the reserve fuel, during which the fuel flow rate of the main fuel is substantially equal to the fuel flow rate of the reserve fuel, the fuel flow rate of the main fuel is increased to a regular flow rate. A fuel switching method for a fuel cell power generator, characterized in that: 4. The fuel switching method for a fuel cell power generator according to claim 1, wherein the schedule control is performed such that when the fuel is switched from the spare fuel to the main fuel again, the fuel remains in the fuel processing system. For a certain period of time until the spare fuel reaches the reformer,
A fuel cell, wherein the steam flow rate is reduced to a steam flow rate corresponding to the fuel flow rate of the main fuel after flowing a flow rate substantially equal to a flow rate corresponding to the spare fuel which has been flowing up to now. A method for switching fuel in a power generator. 5. The fuel switching method for a fuel cell power generator according to claim 1, wherein the schedule control is performed such that when the fuel is switched from the reserve fuel to the main fuel again, the fuel remains in the fuel processing system. For a certain period of time until the spare fuel reaches the reformer,
The increase in the fuel flow rate of the main fuel and the decrease in the fuel flow rate of the reserve fuel are performed gently while monitoring both the fuel flow rates of the main fuel and the reserve fuel, and the fuel flow rate of the reserve fuel is gradually reduced. In the meantime, the steam flow rate is reduced to a steam flow rate corresponding to the fuel flow rate of the main fuel after flowing the flow rate substantially equal to the flow rate corresponding to the spare fuel which has been flowing until now. A fuel switching method for a fuel cell power generator. 6. The fuel switching method for a fuel cell power generator according to claim 1, wherein the schedule control is performed such that when the fuel is switched from the spare fuel to the main fuel again, the fuel remains in the fuel processing system. For a certain period of time until the spare fuel reaches the reformer,
The fuel flow rate of the reserve fuel is gradually reduced, and during this time, the fuel flow rate of the main fuel is made to flow at a flow rate substantially equal to the fuel flow rate of the reserve fuel, and then the fuel flow rate of the main fuel is increased to a normal flow rate. Wherein the fuel flow rate is reduced to a steam flow rate corresponding to the fuel flow rate of the main fuel. 7. A main fuel supply system for supplying a main fuel mainly composed of methane such as city gas and LNG, and a spare fuel such as LPG, naphtha, kerosene and the like different from the main fuel of the main fuel supply system. A fuel supply system comprising an emergency spare fuel supply system; a reformer for mixing fuel supplied from the fuel supply system with steam and reforming the mixture with a reforming catalyst into hydrogen gas; A fuel cell main body that electrochemically reacts hydrogen gas with oxygen to convert it into electric energy; and a fuel that switches fuel from the main fuel to a spare fuel to continue power generation operation when necessary in an emergency or the like. A switching function and a ratio of the number of water vapor molecules in the process gas to the number of carbon atoms in the process gas at the inlet of the catalyst layer in the reforming pipe in the reformer when the fuel switching from the spare fuel to the main fuel is resumed after the fuel switching. S / C ratio And a fuel switching means having a schedule control function for controlling at least one of the flow rates of the main fuel and the spare fuel or the flow rate of the steam so that the flow rate does not fall below a predetermined value. Fuel cell power plant.