JP3239540B2 - Temperature control method of reformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the temperature of a reformer, and more particularly to a method for controlling the temperature of a plate-type reformer in a molten carbonate fuel cell.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features that are not found in conventional power generation devices, such as high efficiency and little impact on the environment, and have attracted attention as power generation systems following hydro, thermal and nuclear power. Are being researched and developed in various countries around the world. In particular, in a power generation facility using a molten carbonate fuel cell using natural gas as a fuel, as shown in FIG. 4, a reformer 10 for reforming a fuel gas 1 such as natural gas into an anode gas 2 containing hydrogen, The fuel cell 20 generally includes a fuel cell 20 that generates electricity from the anode gas 2 and the cathode gas 3 containing oxygen. The anode gas produced by the reformer is supplied to the fuel cell, and most of the anode gas is generated in the fuel cell. After consuming 80%, for example, the combustion chamber C of the reformer 10 is used as the anode exhaust gas 4.
o. The fuel gas 1 is preheated by the fuel preheater 11 and enters the reforming chamber Re of the reformer. In the reformer, combustible components in anode exhaust gas (hydrogen, carbon monoxide, methane, etc.)
Is burned in the combustion chamber, and the reforming chamber Re is heated by the high-temperature combustion gas to reform the fuel flowing inside. The combustion exhaust gas 5 that has exited the reforming chamber is heat-recovered by the air preheater 32 in the exhaust gas circulation line 30, water is removed by the condenser 33 and the steam separator 34, and is removed by the turbine compressor (power recovery device 40). The pressurized air 6 is mixed, and the mixed gas is heated by the air preheater 32 and merges with the cathode gas 3. As a result, carbon dioxide generated on the anode side of the battery enters the cathode gas 3 for the fuel cell via the combustion exhaust gas 5 and supplies carbon dioxide required for the cathode reaction of the fuel cell to the cathode side C. A part of the cathode gas 3 reacts in the fuel cell to form a cathode exhaust gas 7, a part of which is recirculated to the cathode inlet side, and a part of which is supplied to the combustion chamber Co of the reformer 10 and the anode exhaust gas 4. Is burned, and the remainder is supplied to the power recovery device 40 to be recovered in pressure and discharged out of the system. Reference numeral 22 denotes a storage container of the fuel cell, and reference numeral 8 denotes a purge gas supplied to the storage container.

[0003]

The reformer 10 in the above-described fuel cell power generator includes a reforming chamber Re and a combustion chamber Co.
Are formed in a plate shape, and are alternately laminated (a plate-type reformer). In the conventional temperature control of such a reformer, the temperature of the reforming chamber Re is detected and the combustion chamber Co is detected.
Was controlling the flow rate of fuel to be supplied. However, in such temperature control, after the temperature of the combustion chamber Co rises, the reforming chamber Re
There is a time lag until the temperature of the fuel cell actually rises, so that there is a problem that the control delay is large with respect to the load fluctuation of the fuel cell. Further, due to this control delay, when the temperature of the reforming chamber Re is increased in a short time, the temperature of the combustion chamber Co excessively increases,
There is a problem that the internal combustion catalyst may be damaged. Further, even if an attempt is made to maintain a constant temperature after the temperature of the reforming chamber Re is increased due to control delay, the temperature of the reforming chamber Re continues to rise due to the heat transfer from the overheated combustion chamber Co, and the reforming of the reforming chamber Re is performed. There is a problem that the catalyst may be damaged.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a method of controlling the temperature of a reformer which has a small control delay and can prevent overheating of the combustion chamber Co and the reforming chamber Re.

[0005]

According to the present invention, there is provided a combustion chamber for burning an anode exhaust gas discharged from a fuel cell with a cathode exhaust gas, and heating the fuel gas by the heat of the combustion chamber to reform the fuel gas into an anode gas. In a method for controlling the temperature of a reformer including a reforming chamber, the combustion of anode exhaust gas and cathode exhaust gas in the combustion chamber is performed by catalytic combustion, and the flow of combustion gas in the combustion chamber and the flow of fuel gas in the reforming chamber are performed. A counter-current flow, and a reheating line for supplying fuel gas to the anode exhaust gas, an air line for supplying low-temperature air to the cathode exhaust gas, and a temperature sensor for detecting the temperature of the upstream of the combustion chamber, Detecting the temperature of the upstream portion of the combustion chamber with a sensor, and controlling the fuel gas flow rate of the reheating line or the low-temperature air flow rate of the air line so that the detected temperature falls within a predetermined range. A method for controlling the temperature of a reformer is provided.

[0006]

In the plate-type reformer, the plate-shaped reforming chambers Re and the combustion chambers Co are alternately stacked, and the flow of the combustion gas flowing through the combustion chambers Co (combustion side) and the reforming flow flowing through the reforming chambers Re. The flow is opposite to the flow of the raw gas (reforming side). Further, the combustion speed by the catalytic combustion is extremely high, and when the anode exhaust gas and the cathode exhaust gas come into contact with the combustion catalyst on the combustion side, the combustion is completed in a short time, and the temperature of the upstream part of the combustion chamber Co becomes the maximum temperature on the combustion side. I understood. Further, it was found that the temperature of the combustion chamber Co was slightly higher (for example, several tens to one hundred and several tens of degrees Celsius) over the entire flow than the temperature of the reforming chamber Re because of the counterflow. The present invention is based on such a new finding.

That is, according to the configuration of the present invention, the maximum temperature of the combustion chamber is detected by the temperature sensor for detecting the temperature of the upstream of the combustion chamber of the reformer, and the detected temperature is set within a predetermined range. Since the fuel gas flow rate of the reheating line or the low-temperature air flow rate of the air line is controlled, the temperature of the combustion chamber Co can be directly controlled to reduce the time delay of the temperature of the reforming chamber Re,
The control delay with respect to the fuel cell load fluctuation can be reduced. Further, even when the temperature of the reforming chamber Re is raised in a short time, the maximum temperature of the combustion chamber Co is directly controlled, so that damage to the combustion catalyst can be avoided. Further, even when the temperature of the reforming chamber Re is maintained at a constant temperature after the temperature is raised, the overheating of the combustion chamber Co can be prevented, so that the overheating of the reforming chamber Re having a lower temperature than the combustion chamber Co can be automatically avoided, and Damage can be prevented.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals. FIG. 1 is a partial configuration diagram of a fuel cell power generation device for performing a method according to the present invention. The overall configuration of the fuel cell power generator is substantially the same as the configuration shown in FIG. In FIG. 1, the reformer 10 burns the anode exhaust gas 4 exiting the fuel cell 20 (FIG. 4) with the cathode exhaust gas 7, and reforms the fuel gas 1 into the anode gas 2 by using the heat. . In addition, this apparatus has a reheating line 12 for supplying fuel gas to the anode exhaust gas 4.
And an air line 14 for supplying low-temperature air to the cathode exhaust gas 7, and a fuel flow control valve 13 for adjusting the flow rate of the fuel gas is provided in the reheating line 12.
Is provided with an air flow control valve 15 for controlling the flow rate of low-temperature air. Further, the apparatus has a temperature sensor 16 for detecting the temperature of the upstream portion of the combustion chamber of the reformer 10, and a control for controlling the fuel flow control valve 13 or the air flow control valve 15 in accordance with the detected temperature of the temperature sensor 16. Device 18.

FIG. 2 is a control system diagram showing the contents of control by the control device 18. As shown in FIG. The controller 18 detects the temperature of the upstream portion of the combustion chamber by the temperature sensor 16 and controls the fuel gas flow rate of the reheating line 12 or the low-temperature air flow rate of the air line 14 so that the detected temperature falls within a predetermined range. That is, when the detected temperature T is, for example, lower than 750 ° C., the flow rate of the fuel gas is adjusted by the fuel flow rate control valve 13 of the additional heating line 12, and the heat generation in the combustion chamber of the reformer 10 is increased to increase the combustion chamber temperature. Raise. Conversely, if the detected temperature T is, for example, 80
When the temperature is equal to or higher than 0 ° C., the flow rate of the cooling air is adjusted by the air flow rate adjusting valve 15 of the air line 14 to lower the temperature of the combustion chamber. Thereby, the temperature of the upstream part of the combustion chamber can be maintained in a predetermined range (for example, 750 to 800 ° C.).

FIG. 3 schematically shows the temperature distribution on the combustion side and the reforming side in the plate type reformer. In the plate-type reformer, the plate-shaped reforming chamber Re and the combustion chamber Co are alternately stacked, and the flow of the combustion gas flowing through the combustion chamber Co (combustion side) and the flow rate of the reformed gas flowing through the reforming chamber Re are changed. The flow (reforming side) is a counter flow. Further, the combustion speed by the catalytic combustion is extremely high, and when the anode exhaust gas and the cathode exhaust gas come into contact with the combustion catalyst on the combustion side, the combustion is completed in a short time, and the temperature of the upstream portion (indicated by A in the figure) of the combustion chamber Co increases. Side (eg, 800 ° C.). In addition, because of the counterflow, the temperature of the combustion chamber Co is slightly higher (for example, several tens to one hundred and several tens degrees Celsius) than the temperature of the reforming chamber Re over the entire flow. Therefore, the temperature at point A (upstream of the combustion chamber) in this figure is detected, and the fuel gas flow rate in the reheating line 12 or the air flow rate in the air line 14 is controlled so that the detected temperature falls within a predetermined range. If the temperature of the combustion chamber Co can be directly controlled, the time delay of the temperature of the reforming chamber Re can be reduced,
The control delay with respect to the fuel cell load fluctuation can be reduced. Further, even when the temperature of the reforming chamber Re is raised in a short time, the maximum temperature of the combustion chamber Co is directly controlled, so that damage to the combustion catalyst can be avoided. Further, even when the temperature of the reforming chamber Re is maintained at a constant temperature after the temperature is raised, the overheating of the combustion chamber Co can be prevented, so that the overheating of the reforming chamber Re having a lower temperature than the combustion chamber Co can be automatically avoided, and Damage can be prevented.

[0011]

As described above, the temperature control method for a reformer according to the present invention has an excellent effect of reducing the control delay and preventing overheating of the combustion chamber Co and the reforming chamber Re. .

[Brief description of the drawings]

FIG. 1 is a partial configuration diagram of a fuel cell power generation device for performing a method according to the present invention.

FIG. 2 is a control system diagram of a control device.

FIG. 3 is a temperature distribution diagram of a combustion side and a reforming side in a plate-type reformer.

FIG. 4 is an overall configuration diagram of a conventional fuel cell power generation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel gas 2 Anode gas 3 Cathode gas 4 Anode exhaust gas 5 Combustion exhaust gas 6 Air 7 Cathode exhaust gas 8 Purge gas 10 Reformer 11 Fuel preheater 12 Reheating line 13 Fuel flow control valve 14 Air line 15 Air flow control valve 16 Temperature sensor REFERENCE SIGNS LIST 18 control device 20 fuel cell 22 containment vessel 30 exhaust gas circulation line 32 air preheater 33 condenser 34 steam-water separator 40 power recovery device Re reforming chamber Co combustion chamber A anode side C cathode side

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/04 H01M 8/06

Claims (1)

(57) [Claims] And 1. A fuel cell combustion chamber Ru by burning anode exhaust gas in the cathode exhaust gas emitted, and a reforming chamber for reforming the anode gas by heating the fuel gas in the heat of the combustion chamber <br The method of controlling the temperature of the reformer, wherein the combustion of the anode exhaust gas and the cathode exhaust gas in the combustion chamber
By the catalytic combustion, the flow of the combustion gas in the combustion chamber and the fuel gas in the reforming chamber
A counter-current flow, and a reheating line for supplying fuel gas to the anode exhaust gas, an air line for supplying low-temperature air to the cathode exhaust gas, and a temperature sensor for detecting a temperature of an upstream portion of the combustion chamber; The temperature of the upstream of the combustion chamber is detected by a sensor,
A method for controlling the temperature of a reformer, comprising: controlling a fuel gas flow rate in the reheating line or a low-temperature air flow rate in the air line so that the detected temperature falls within a predetermined range.