JP2791130B2 - Fuel cell power plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial Application Field) The present invention relates to a fuel cell power plant that can shorten the startup time of the plant.

(Prior art) In recent years, fuel cell power generation systems that have been put into practical use are:
The energy of a fuel such as hydrogen is directly converted into electric energy by an electrochemical reaction occurring in the fuel cell.As long as the fuel and the oxidant such as air are supplied to the fuel cell, Electric energy can be extracted with high conversion efficiency.

In addition, this type of fuel cell power generation system often includes a fuel reforming system in order to obtain hydrogen gas as fuel for a fuel cell by steam reforming a source gas such as methane. In such a reformer of a fuel reforming system, a raw material gas such as methane and steam supplied through a raw material gas line and a steam line are provided inside a reforming reaction tube in which a reforming reaction catalyst layer is provided. And reforming the raw material gas into a hydrogen-rich reformed gas by passing a high-temperature heating gas obtained by combustion in a combustion chamber outside the reforming reaction tube. ,further,
After a reformed gas having a higher hydrogen concentration is passed through a carbon monoxide converter, the reformed gas is supplied to a fuel cell as a load.

FIG. 4 shows a configuration example of a fuel cell power plant equipped with this type of fuel reformer. In the figure, 1
Is a reformer, and the combustion fuel and combustion air supplied through a reforming reaction tube 2 in which a reforming reaction catalyst layer is provided, a combustion fuel supply line 3 and a combustion air supply line 4, respectively. And a burner 7 for burning in the combustion chamber 6. Reference numerals 8 and 9 denote a source gas supply device and a steam supply device for supplying a hydrocarbon-based source gas (methane and the like) and steam, respectively.
The raw material gas and the water vapor supplied through 5 and 16 are mixed and introduced into the inside of the reforming reaction tube 2. In the reformer 1, the raw material gas is reformed at a high temperature of about 600 ° C. to 800 ° C. by passing the high temperature heating gas obtained by the combustion in the combustion chamber 6 outside the reforming reaction tube 2. To a high-temperature carbon monoxide converter 10 (operating temperature of about 400 ° C.) having a shift catalyst layer, and then to a low-temperature carbon monoxide converter 11 (operating temperature of about 200 ° C.) After being introduced and converted into a reformed gas having a higher hydrogen concentration, excess water in the gas is removed by a contact cooler 13, and the fuel is supplied to a fuel electrode 12 a of a fuel cell 12 as a load through a fuel supply valve 5. It is configured to be supplied as. On the other hand, the air supply valve 14 is connected to the air electrode 12b of the fuel cell 12.
The air is supplied via.

Furthermore, the reformer reaction tube 2, a high-temperature carbon monoxide converter
10, heat exchangers 17, 18, 19, and 20 are provided at the inlet sides of the low-temperature carbon monoxide converter 11 and the contact cooler 13, respectively. Is adjusted to an appropriate level for each reaction. For example, the heat exchanger 17 provided at the inlet of the reformer reaction tube 2 functions as a heater for the mixed gas of the raw material gas and the steam, and the other heat exchangers 18, 19, and 20 serve for the reformed gas. Work as a cooler.

Further, in the fuel cell power plant shown in FIG. 4, a heating system used when starting the plant is provided. That is, the temperature rise circulation blower 21 is provided on a line 24 which is branched from a line 23 from the contact cooler 13 to the fuel cell 12 and is connected to an inert gas supply line 22. The temperature raising circulation blower 21 is stopped during the normal reforming operation, and is used at the time of raising the temperature of the fuel reforming system when starting the fuel cell power plant. That is, when the fuel cell power plant is started up and heated, the supply valves 15 and 16 for the raw material gas and water vapor and the fuel supply valve 5 for the fuel cell are closed, and an inert gas supply line such as nitrogen is first supplied. twenty two
The inert gas is supplied to the fuel reforming system and sealed therein, and the burner 7 of the reformer is burned while rotating the blower 21 for heating and circulating. The equipment of the fuel reforming system is gradually heated and heated. After the reformer, the carbon monoxide converter, and the heat exchanger are each heated to an appropriate temperature level necessary for the reforming reaction in this way, the raw material gas and steam are supplied to start the reforming reaction. It is configured to be.

(Problems to be Solved by the Invention) However, the conventional fuel cell power plant configured as described above has problems to be solved as described below.

That is, in general, in a large-capacity fuel cell power plant having a plant output of MW class or more, the amounts of the catalyst layer of the reformer reaction tube and the catalyst layer of the carbon monoxide converter included in the fuel reforming system are reduced. As a result, the heat capacity of the fuel reforming system increases. For this reason, in the method of raising the temperature at the time of starting the plant as shown in FIG. 4, it takes 6 to 8 hours to raise the temperature of each device until it reaches an appropriate level. It is desired to shorten this. In particular, when a fuel cell power plant is operated as a power station for meeting an intermediate load demand that is required to be repeatedly started and stopped according to a weekly schedule, a short start-up is indispensable.

As one of the methods of shortening the time for raising the temperature of the fuel reforming system, it is conceivable to increase the combustion amount of the reformer burner 7 which is a heating source at the time of raising the temperature. However, there is a drawback that the temperature of the reaction tube 2 becomes excessively high and the reaction tube and the catalyst layer are destroyed. Therefore, there is a limit to the increase in the amount of combustion, and the heating time cannot be shortened significantly. .

The present invention has been proposed in order to solve the following disadvantages, and an object of the present invention is to provide an efficient fuel cell power plant capable of shortening the startup time of the plant.

[Means for Solving the Problems] The invention according to claim 1 is a fuel cell power generation including a fuel reforming system having a reformer, a carbon monoxide converter, and a heat exchanger. In the plant, a warming heater is provided on or inside the container of the carbon monoxide converter, a bypass line is formed between the inlet side and the outlet side, and a flow control valve is provided on the line. It is assumed that.

According to a second aspect of the present invention, there is provided a fuel cell power plant including a fuel reforming system having a reformer, a carbon monoxide converter, a heat exchanger, and a desulfurizer. A heat retention heater is provided on or inside the outer surface of at least one of the vessels of the desulfurizer, and at least one of the carbon monoxide converter and the desulfurizer is provided with a bypass line connecting the inlet side and the outlet side. , A flow control valve is provided on the line.

(Operation) According to the fuel cell power plant of the present invention, a device having a large heat capacity that causes a delay in temperature rise of the fuel reforming system, such as a carbon monoxide converter or a desulfurizer, is stopped while the plant is stopped. Since the temperature can be maintained at a more constant temperature level and there is no need to circulate a heating gas for raising the temperature to these devices at the time of starting the plant, the plant can be started in a short time.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to FIGS. 1 to 3. The same members as those of the conventional type shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

First Embodiment In the present embodiment, as shown in FIG. 1, heat retaining heaters 30 and 31 are provided on the outer surfaces of the containers of the high-temperature carbon monoxide converter 10 and the low-temperature carbon monoxide converter 11, respectively. I have. Each transformer is formed with bypass lines 32, 33 connecting the inlet side and the outlet side thereof, and flow control valves 34, 35 are provided on the lines.

In the fuel cell power plant according to the present embodiment having such a configuration, the temperature is raised at the time of startup as described below. That is, the warming heaters 30, 3 provided on the outer surfaces of the containers of the high-temperature carbon monoxide converter 10 and the low-temperature carbon monoxide converter 11
1 operates even when the operation of the fuel cell power plant is stopped, and keeps the temperature of each carbon monoxide converter below a certain temperature level. Controlling this temperature level to an appropriate value can be easily realized by using a temperature sensor or a heater control device (not shown), and the heat retention level is set to the operating temperature during normal operation. It can also be set to maintain close temperature levels.

With the carbon monoxide converters 10 and 11 kept warm in this way,
Start heating the plant. That is, an inert gas is supplied to the fuel reforming system from an inert gas supply line 22 such as nitrogen and sealed therein, and the burner 7 of the reformer is burned while rotating the blower 21 for heating and circulation. Is given to the inert gas, thereby gradually heating the above-mentioned fuel reforming system equipment and raising its temperature. At this time, the bypass line 3 of the carbon monoxide
Opening the flow control valves 34, 35 provided on the 2, 33, the heated circulating gas is the reforming reaction tube 2, except for the carbon monoxide converters 10, 11, the heat exchangers 17, 18, 19, 20 And a portion such as a pipe connecting them is heated. After the temperature of these devices has risen sufficiently, the heating circulating gas is closed by closing the flow rate control valves 34 and 35, so that the carbon monoxide
Make it flow into 1 too. In this case, the opening degrees of the flow control valves 34 and 35 are finally adjusted so that each device of the fuel reforming system reaches the target temperature increase.

As described above, according to the present embodiment, the carbon monoxide converter having a large heat capacity occupying the center of the entire fuel reforming system is kept at a constant temperature level while the plant is stopped, and is circulated when the temperature rises. By passing the heated circulating gas through the bypass lines 32 and 33 of the carbon monoxide converter, the equipment other than the carbon monoxide transformer can be heated. Can be greatly reduced, and the temperature can be raised in a short time when the plant is started. Furthermore, after the temperature of equipment other than the carbon monoxide converter reaches a certain level, the opening of the flow control valve on the bypass line is adjusted, and the heating circulating gas is also supplied to the carbon monoxide converter. Specifically, the temperature of the entire reforming system can be raised in a short time at a balanced temperature.

Second Embodiment In this embodiment, as shown in FIG. 2, the present invention is applied to a fuel reforming system provided with a desulfurizer for desulfurizing a raw material gas. .

That is, in the embodiment shown in FIG. 2, a raw material gas such as methane supplied from the raw material gas supply device 8 of the fuel reforming system via the supply valve 15 is supplied to the desulfurizer 41 via the heat exchanger 40.
To the steam supply device 9
It is configured to be mixed with the reforming steam supplied through 16 and to be introduced into the reforming reaction tube 2 of the reformer 1.
A heat retention heater 42 is provided on the outer surface of the vessel of the desulfurizer 41. Further, the desulfurizer 41 is formed with a bypass line 43 connecting the inlet side and the outlet side thereof, and a flow control valve is provided on the line. 44 are provided. In addition, since the configuration of other parts is the same as that of the first embodiment, the description is omitted.

The heat exchanger 40 is for adjusting the temperature of the inflow gas so that the desulfurizer 41 can perform an appropriate desulfurization operation, and generally acts as a heater for the raw material gas for reforming. I do. As the desulfurizer, for example, a desulfurizer and a hydrogen sulfide adsorber in the case of a hydrodesulfurizer are used, and a sulfur adsorber in which carbon adsorbed particles are sealed is used.

As described above, also in the present embodiment, as in the first embodiment, the heat retaining heater 42 disposed in the desulfurizer 41 operates even while the operation of the fuel cell power plant is stopped, and the desulfurizer 41 is provided. The temperature is kept below a certain level. Then, with the desulfurizer 41 kept warm, the temperature of the plant is started to rise. That is, an inert gas supply line 22 such as nitrogen
The inert gas is supplied to the fuel reforming system and sealed therein, and the burner 7 of the reformer is burned while rotating the blower 21 for heating and circulating. The equipment of the fuel reforming system is gradually heated and heated. At this time,
Flow control valve provided on bypass wine 43 of desulfurizer 41
Open 44, and the heated circulating gas raises the temperature of the reforming reaction tube 2, heat exchangers 17, 18, 19, 20, 40 and the pipes connecting them, excluding the desulfurizer 41. I do. Then, after the temperature of these devices has sufficiently risen, the heating circulating gas is caused to flow into the desulfurizer 41 by closing the flow control valve 44. In this case, finally, the opening of the flow control valve 44 is adjusted so that each device of the fuel reforming system reaches its target temperature for heating.

In the embodiment shown in FIG. 2, the carbon monoxide converter is also provided with the heat retention heater, the bypass line, and the flow control valve shown in the first embodiment. Needless to say, an effect can be obtained.

As described above, according to the present embodiment, the carbon monoxide converter and the desulfurizer are kept at a constant temperature level from the time when the plant is stopped, and the heating circulating gas circulated at the time of raising the temperature is supplied to the carbon monoxide converter. By passing through the bypass line and desulfurizer bypass line, the equipment other than the carbon monoxide converter and desulfurizer can be heated, greatly reducing the heat load when the plant is started up. In addition, the temperature can be raised in a short time when the plant is started. Furthermore, after the temperature rise of equipment other than the carbon monoxide converter and the desulfurizer reaches a certain level, the opening degree of the flow control valve provided on each bypass line is adjusted,
The heating circulating gas is also passed to the carbon monoxide converter and desulfurizer,
Finally, the temperature of the entire reforming system can be raised in a short time at a balanced temperature. In particular, since the desulfurizer 41 is disposed upstream of the reformer 1, when the temperature is increased by circulating an inert gas generated by heating the reformer burner, the desulfurizer 41 is farthest from the heat source. Not easy to warm. Therefore, quickening the temperature rise of the desulfurizer as in the present embodiment greatly contributes to shortening of the temperature rise time of the entire fuel cell power plant, and excellent effects can be expected.

Third Embodiment In the present embodiment, as shown in FIG. 3, a line 50 introduced into the heating and circulating blower 21 is provided with a contact cooler.
It is drawn from thirteen inlet lines 51. The configuration of other parts is the same as that of the second embodiment shown in FIG.
Description is omitted.

In the fuel cell power plant according to the present embodiment having such a configuration, the inert heating circulating gas heated by the reformer burner 7 flows into the contact cooler 13 when the temperature of the fuel reforming system is raised. To prevent cooling. Therefore, the temperature of the inert gas circulated to the desulfurizer 41 is sufficiently high, and the temperature of the heat exchangers and pipes before and after the desulfurizer is quickly increased at the initial stage of the temperature increase. The effect of shortening the heating time is great.

Other Embodiments The present invention is not limited to the embodiments described above,
As shown in the third embodiment, the method of drawing out the line introduced into the heating and circulating blower from the inlet side of the contact cooler can be applied to the first embodiment shown in FIG. Further, the warming heater provided in the carbon monoxide converter or the desulfurizer may be provided not inside the container but inside the container. Further, the warming heater may be an electric heater, a steam or oil heater.

[Effects of the Invention] As described above, according to the present invention, a heat retention heater is provided on the outer surface or inside of a container of a carbon monoxide converter or a desulfurizer, and a bypass line connecting the inlet side and the outlet side thereof is formed. However, by providing a flow control valve on the line, it is possible to provide an efficient fuel cell power plant that can reduce the startup time of the plant.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a fuel cell power plant according to the present invention, FIG. 2 is a block diagram showing a second embodiment of the present invention, and FIG. 3 shows a third embodiment of the present invention. FIG. 4 is a block diagram showing an example of a conventional fuel cell power plant. DESCRIPTION OF SYMBOLS 1 ... Reformer, 2 ... Reforming reaction tube, 3 ... Combustion fuel supply line, 4 ... Combustion air supply line, 5 ... Fuel supply valve, 6 ... Combustion chamber, 7 ... Burner , 8 ... raw material gas supply device, 9 ... steam supply device, 10 ... high temperature carbon monoxide converter, 11 ... low temperature carbon monoxide converter, 12 ... fuel cell, 12 a ... fuel electrode, 12 b ... … Air electrode, 13… contact cooler, 14… air supply valve, 15, 16… supply valve, 17, 18, 1
9, 20 heat exchanger, 21 heating circulation blower, 22 inert gas supply line, 30, 31 heater, 32, 33 bypass line, 34, 35 flow control valve , 40 ... heat exchanger, 41 ... desulfurizer, 42 ... heater, 43 ... bypass line, 44 ... flow control valve.

Claims (2)

(57) [Claims] 1. A fuel cell power plant including a fuel reforming system having a reformer, a carbon monoxide converter, and a heat exchanger, wherein a heat is retained on an outer surface of or inside a vessel of the carbon monoxide converter. A heater is provided, and the carbon monoxide converter is formed with a bypass line connecting an inlet side and an outlet side thereof,
A fuel cell power plant wherein a flow control valve is provided on the line. 2. A fuel cell power plant including a fuel reforming system comprising a reformer, a carbon monoxide converter, a heat exchanger, and a desulfurizer, wherein at least one of the carbon monoxide converter and the desulfurizer is provided. A warming heater is provided on or in one of the outer surfaces of the container, and at least one of the carbon monoxide converter and the desulfurizer is formed with a bypass line connecting an inlet side and an outlet side thereof, A fuel cell power plant wherein a flow control valve is provided on the line.