JPH04269460A - How to raise the temperature of a fuel cell plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for increasing the temperature of a fuel cell plant, such as a phosphoric acid fuel cell plant, a molten carbonate fuel cell plant, or a solid oxide fuel cell plant.

0002

[Prior Art] Among conventional fuel cell plants, a molten carbonate fuel cell plant has a fuel cell 1 as shown in FIG.
Hydrogen is supplied to the anode electrode 2 via the fuel supply line 6, while oxygen is supplied to the cathode electrode 4 via the air supply line 9 to cause a cell reaction and generate electricity. The battery 1 is a combination (cell) of an anode 2 and a cathode 4 stacked in several layers.

[0003] The fuel supply line 6 includes an anode electrode 2.
A reformer 7 is disposed on the upstream side of the anode exhaust gas line 3 and generates hydrogen by subjecting raw fuel Z such as natural gas to a reforming reaction with steam H at high temperature. 2, and the fuel cell 1
An anode blower 8 is provided to supply surplus fuel from the fuel to the reformer 7. On the other hand, the cathode circulation system 5 includes air supply lines 9 upstream and downstream of the cathode 4 for supplying air E for supplying oxygen to the cathode 4.
and a cathode exhaust gas line 10 connected downstream of the cathode 4, and in the middle of the cathode circulation system 5, there is a cathode circulation blower 11 that circulates the cathode exhaust gas discharged from the fuel cell 1. It is provided.

[0004] Also, a branch circulation line 12 is connected to the anode exhaust gas line 3, which branches from the downstream side of the anode blower 8 and leads to the upstream side of the reformer 7 of the fuel supply line 6. is connected to a branch supply line 19 that branches from the upstream side of the reformer 7 and leads to the anode exhaust gas line 3.

In the figure, 13 is a fuel supply valve, 14 is a steam supply valve, 15 is an air supply valve, and 20 is a valve provided between the branch part of the branch circulation line 12 and the connection part of the branch supply line 19 of the anode exhaust gas line 3. 21 is an on-off valve provided in the middle of the branch circulation line 12, and E' is an on-off valve provided in the middle of the branch circulation line 12; In addition, the reformer 7 is connected to the air supply line 9 so that the flue gas can be supplied to the air supply line 9, with the air used to combust the Z.

When starting the fuel cell 1, as shown in FIG. 2, the fuel supply valve 13, steam supply valve 14, and air supply valve 1 are activated.
5. With the on-off valve 20 closed and the on-off valves 21 and 22 open, nitrogen gas N (inert gas) is supplied from the nitrogen gas filling line (not shown) to the branch circulation line 12, and the fuel supply line 6 After exhausting the gas remaining in the anode exhaust gas line 3 from a gas exhaust line (not shown), the nitrogen gas N is driven from the reformer 7 through the fuel supply line 6 to the anode electrode 2 by driving the anode blower 8. At the same time, the raw fuel Z supplied from the branch supply line 19 is combusted by the air E', and the combustion exhaust gas is passed from the air supply line 9 through the cathode 4 and discharged from the cathode exhaust gas line 10. Incidentally, at this time, the cathode circulation blower 11 is stopped.

[0007] As a result, the nitrogen gas N is transferred to the reformer 7.
The temperature is increased by exchanging heat with the combustion exhaust gas, and the temperature of the anode 2 is raised when passing through the anode 2,
On the other hand, due to the combustion of the raw fuel Z and the air E', the reformer 7
At the same time, the combustion exhaust gas raises the temperature of the cathode 4.

[0008] When the temperature of the fuel cell 1 rises to about 650°C and the temperature of the reformer 7 rises to about 800°C, the fuel supply valve 13, the steam supply valve 14, and the air supply The valve 15 and the on-off valve 20 are opened, and the on-off valves 21 and 2 are opened.
2 is closed, raw fuel Z supplied via the fuel supply valve 13 is supplied into the reformer 7, and steam H supplied via the steam supply valve 14 is supplied to the reformer 7, In the reformer 7, hydrogen is generated by a reforming reaction between the raw fuel Z and the steam H at a high temperature, and the hydrogen is supplied to the anode 2, and then the surplus fuel from the anode 2 is The anode blower 8 supplies the reformer 7 with fuel as fuel for the reformer 7.
be returned to.

On the other hand, in the air supply line 9, air E introduced through the air supply valve 15 is supplied to the cathode 4, and then the cathode exhaust gas from the cathode 4 mainly flows to the cathode exhaust gas line 10. However, a part of it is recirculated by driving the cathode circulation blower 11 of the cathode circulation system 5, and in the air supply line 9, the air supply valve 1
After being mixed with low-temperature air E supplied through 5 and lowered to an appropriate temperature, it is returned to the cathode 4. This allows a large amount of gas to flow into the cathode 4,
This prevents the fuel cell 1 from becoming hotter than necessary due to cell reactions.

0010

[Problems to be Solved by the Invention] During the start-up operation of a fuel cell plant as described above, the fuel cell 1 is operated slowly and at a speed below a specified speed in order to avoid performance deterioration due to thermal distortion and electrolyte non-uniformity. The temperature must be raised uniformly to a predetermined temperature, and since the temperature is raised by the amount of combustion exhaust gas determined by the restrictions on the temperature raising conditions of the reformer 7, it takes several days to complete the temperature raising.

[0011] Regarding the reformer 7, if it is heated alone, the temperature rise can normally be completed in about 3 to 4 hours, but if both the fuel cell 1 and the reformer 7 are heated at the same time, Therefore, it is necessary to slowly heat the reformer 7 along with the fuel cell 1, and auxiliary equipment such as a pump or compressor for supplying raw fuel Z and a compressor for supplying air E' (not shown) may be heated for a long time. It has to be driven over the entire range, which is very wasteful, and furthermore, the overall temperature increase control is also difficult because the constraints on the temperature increase conditions of the combustion battery 1 and the reformer 7 interfere with each other.

In view of these circumstances, the present invention has been developed to increase the temperature of a fuel cell plant in which the temperature of the fuel cell and the reformer can be raised individually, the power of auxiliary equipment can be saved, and the temperature can be easily controlled. It is intended to provide a method.

[0013]

[Means for Solving the Problems] The present invention provides a method for increasing the temperature of a fuel cell plant equipped with a cathode circulation system and a reformer, in which an inert gas introduced into the cathode circulation system is The inert gas is heated with a heater and circulated through the cathode circulation system to raise the temperature of the fuel cell to a predetermined temperature, while the inert gas is introduced into a reformer circulation system formed to bypass the anode electrode of the fuel cell. The present invention is characterized in that the raw fuel supplied to the reformer is heated by combustion and circulated through the reformer circulation system to raise the temperature of the reformer to a predetermined temperature.

[0014]

[Operation] Therefore, during the startup operation of a fuel cell, the inert gas introduced into the cathode circulation system is heated by the heater and then circulated to the cathode circulation system, and the fuel cell is indirectly heated by the inert gas. Meanwhile, an inert gas is introduced into a reformer circulation system formed to bypass the anode electrode of the fuel cell, and the inert gas is heated by combustion of the raw fuel supplied to the reformer. When the fuel is circulated through the reformer circulation system, the reformer is heated by combustion of the raw fuel completely separately from the fuel cell.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a system of a fuel cell plant in which the method of the present invention is adopted. In the figure, parts given the same reference numerals as in FIG. 2 represent the same parts, and the basic configuration is is almost the same as the conventional one shown in FIG. A gas discharge line and a nitrogen gas filling line (not shown) for replacing air E with nitrogen gas (inert gas) N' are connected to the cathode circulation system 5. A cathode inlet valve 16 is provided between the connection part of the cathode circulation system 5 and the connection part of the reformer 7,
A cathode outlet valve 17 is provided downstream of the branch of the cathode circulation system 5 in the cathode exhaust gas line 10, an anode inlet valve 23 is provided upstream of the anode electrode 2 in the fuel supply line 6, and an anode inlet valve 23 is provided in the anode exhaust gas line 3 on the upstream side of the anode electrode 2. Anode outlet valves 24 are provided upstream of the blowers 8, and the upstream side of the anode inlet valve 23 of the fuel supply line 6 and the downstream side of the anode outlet valve 24 of the anode exhaust gas line 3 are connected to each other by a bypass in which an on-off valve 25 is provided in the middle. line 2
6 to short-circuit the fuel supply line 6, the bypass line 26, the anode exhaust gas line 3, and the branch circulation line 1.
2 and a reformer circulation system 27 that bypasses the anode electrode 2.
Furthermore, the upstream side of the cathode inlet valve 16 of the air supply line 9 and the downstream side of the cathode outlet valve 17 of the cathode exhaust gas line 10 are short-circuited by an exhaust gas bypass line 29 provided with an on-off valve 28 in the middle. At the point.

Next, the operation of the above embodiment will be explained.

In the fuel cell plant, when starting up the fuel cell 1, the cathode inlet valve 16 and the cathode outlet valve 1 are closed.
7 is closed, nitrogen gas N' is supplied to the cathode circulation system 5 instead of the internal gas of the cathode circulation system 5, and the cathode circulation blower 11 is operated to supply nitrogen gas N' to the cathode including the cathode electrode 4. Nitrogen gas N' is circulated within the circulation system 5 and is circulated by operating the heater 18 and appropriately adjusting the supply of heating medium to the heater 18.
The temperature of the nitrogen gas N' is increased at an appropriate rate.
exchanges heat within the fuel cell 1, and the temperature of the fuel cell 1 also gradually rises. At this time, since the fuel cell 1 has a cell arrangement in which the anode electrode 2 and the cathode electrode 4 are arranged alternately as described above, the heated nitrogen gas N' is applied only to the cathode electrode 4. The entire fuel cell 1 can be heated even if it flows.

Next, the nitrogen gas N' whose temperature has decreased by passing through the cathode 4 of the fuel cell 1 is reheated by the heater 18 and sent to the cathode 4 again to heat the fuel cell 1. .

On the other hand, when heating the reformer 7, as shown in FIG.
5. With the cathode inlet valve 16, the cathode outlet valve 17, the on-off valve 20, the anode inlet valve 23, and the anode outlet valve 24 closed, and the on-off valves 21, 22, 25, and 28 open, not shown. After supplying nitrogen gas N (inert gas) from the nitrogen gas filling line to the branch circulation line 12 and discharging the gas remaining in the fuel supply line 6 and the anode exhaust gas line 3 from the gas discharge line (not shown),
While the nitrogen gas N is circulated in the reformer circulation system 27 by driving the anode blower 8 so as to bypass the anode electrode 2, the raw fuel Z is supplied from the branch supply line 19.
The temperature of the reformer 7 is raised by burning it with air E' in the reformer 7, and the combustion exhaust gas is discharged from the cathode exhaust gas line 10 via the air supply line 9, the exhaust gas bypass line 29.

After the temperature rise of the fuel cell 1 and the reformer 7 is completed, the valves 13, 14, 15, 1, which were closed in FIG.
6, 17, 20, 23, 24 are opened, and the open valves 21, 22, 25, 28 are closed, and the heater 1
With the supply of heating medium to 8 being stopped, normal operation is performed as in the conventional case.

[0022] In this way, it becomes possible to raise the temperature of the fuel cell 1 and the reformer 7 individually without being constrained by each other, and when starting up the fuel cell 1, the fuel cell 1 and the reformer 7 are heated individually.
For example, when the temperature rise is completed, e.g.
If you start raising the temperature of the reformer 7 4 hours in advance,
There is no need to drive auxiliary equipment such as the pump or compressor for supplying raw fuel Z or the compressor for supplying air E' for a long time in accordance with the temperature rise of the fuel cell 1, and the overall temperature rise control is also easy. becomes.

It should be noted that the method for increasing the temperature of a fuel cell plant according to the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention. .

[0024]

[Effects of the Invention] As explained above, according to the temperature raising method for a fuel cell plant of the present invention, it is possible to raise the temperature of the fuel cell and the reformer individually, and it is possible to save the power of auxiliary equipment. At the same time, an excellent effect can be achieved in that temperature increase control can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing an example of a fuel cell plant in which the method of the present invention is adopted.

FIG. 2 is a schematic system diagram of a conventional example.

[Explanation of symbols]

1 Fuel cell 2 Anode pole 4 Cathode pole 5 Cathode circulation system 7 Reformer 18 Heater 26 Bypass line 27 Reformer circulation system Z raw fuel N, N' Nitrogen gas (inert gas)

Claims (1)

[Claims] Claim 1: A method for increasing the temperature of a fuel cell plant equipped with a cathode circulation system and a reformer, in which an inert gas introduced into the cathode circulation system is heated by a heater during a fuel cell startup operation, and then the cathode gas is heated by a heater. The inert gas is circulated through a circulation system to raise the temperature of the fuel cell to a predetermined temperature, while the inert gas is introduced into a reformer circulation system formed to bypass the anode electrode of the fuel cell, and the inert gas is supplied to the reformer. A method for raising the temperature of a fuel cell plant, characterized in that the raw fuel is heated by combustion and circulated through the reformer circulation system to raise the temperature of the reformer to a predetermined temperature.