JPH05121087A - Temperature control device of fuel cell power generating device - Google Patents

Abstract

PURPOSE:To allow a blower to manage its work with a minor capacity by permitting the off gas or part of the combustion air to flow through a bypass line so that the temp. of a reaction pipe becomes a level suitable for modification of the raw material which needs modification. CONSTITUTION:The temp. of a reaction pipe 2 is sensed by a temp. sensor 22, and a signal thus detected is fed to a temp. regulator 23, and a flow adjusting valve 20 is controlled on the basis of the deviation of this sensed temp. from the target value for the specified temp. suitable for the modification of the reaction pipe 2. Accordingly a part of the combustion air becomes a combustion air amount controlled by the flow adjusting valve 20. flows through a bypass line 21 without being preheated by a heat exchanger 10, and is supplied to a burner 4 together with the remaining portion of combustion air preheated by the heat exchanger 10, so that the temp. of the reaction pipe 2 is controlled to a specified level. Therefore. the control can be made with quick response and stability, and also the capacity of blower may remain small because the combustion air amount is controlled with constant air-fuel ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly comprises a fuel reformer and a fuel cell, and heats a reaction tube by a heat medium produced by combustion of off-gas from a fuel electrode of the fuel cell in the fuel reformer. The present invention relates to a temperature control device for a fuel cell power generator that controls the temperature of the reaction tube when reforming the reforming raw material flowing through the reaction tube into a gas rich in hydrogen.

[0002]

2. Description of the Related Art A fuel cell power generator is mainly composed of a fuel reformer and a fuel cell, and is used for combustion in the fuel reformer by combustion exhaust gas discharged from the fuel reformer. There is known a fuel cell power generation device having a system shown in FIG. 3 that includes a heat exchanger as a heater that preheats off-gas and combustion air discharged from the exhaust gas.

In FIG. 3, a fuel reformer 1 comprises a furnace vessel 3 containing a reaction tube 2 filled with a catalyst, and a burner 4 provided above the furnace vessel 3. The fuel cell 5 is composed of an electrolyte holding layer 6 and a fuel electrode 7 and an oxidant electrode 8 which sandwich the electrolyte holding layer 6 therebetween. Heat exchanger 1 as a heater
0 indicates that the combustion exhaust gas discharged from the furnace container 3 of the fuel reformer 1 is supplied to the burner 4 of the fuel reformer 1 and the off gas containing hydrogen that does not contribute to the cell reaction discharged from the fuel electrode 7 of the fuel cell 5. Preheat the offgas and the combustion air by exchanging heat with the combustion air for offgas combustion.

The reforming raw material supply system 11 is connected to the reaction tube 2 of the fuel reformer 1 and supplies the reforming raw material to which steam has been added to the reaction tube 2. The reformed gas supply system 12 is connected to the reaction tube 2 and the fuel electrode 7 of the fuel cell 5, and supplies the hydrogen-rich reformed gas discharged from the reaction tube 2 to the fuel electrode 7. The off-gas discharge system 13 is connected to the fuel electrode 7 and the burner 4 of the fuel reformer 1 via the heat exchanger 10, and supplies the off-gas discharged from the fuel electrode 7 to the burner 4 via the heat exchanger 10. ..

The combustion air supply system 14 is equipped with a blower 15 and is connected to the burner 4 via a heat exchanger 10.
The air sucked by 5 is pressurized and supplied to the burner 4 as combustion air via the heat exchanger 10. Exhaust gas exhaust system 16
Is connected to the furnace vessel 3 via a heat exchanger 10, and the combustion exhaust gas of the combustion gas burned by the burner 4 in the furnace vessel 3 is discharged to the outside via the heat exchanger 10.

The air supply system 17 is an oxidizer electrode 8 of the fuel cell 5.
And supplies air to the oxidant electrode 8 as oxidant gas. The air discharge system 18 is connected to the oxidant electrode 8 and discharges air that has undergone a battery reaction from the oxidant electrode 8 to the outside.

With such a configuration, the amount of off-gas discharged from the fuel electrode 7 of the fuel cell 5 corresponding to the load of the fuel cell 5 is supplied to the burner 4 via the off-gas discharge system 13, and is supplied to the burner 4 by the blower 15. Combustion is performed by the supplied combustion air, and the combustion gas generated at this time heats the reaction tube 2. On the other hand, the reforming raw material to which steam is added is supplied to the reaction tube 2 through the reforming raw material supply system 11 and heated to the reaction tube 2.
It flows through the inside and is reformed into a gas rich in hydrogen under the catalyst to become a reformed gas.

The reformed gas is supplied to the fuel electrode 7 of the fuel cell 5 through the reformed gas supply system 12, and the reformed gas and the air supplied to the oxidant electrode 8 through the air supply system 17 are used as fuel. The battery 5 causes a battery reaction to generate power. At this time, the off gas discharged from the fuel electrode 7 is supplied to the burner 4 as described above, while the air discharged from the oxidant electrode 8 is discharged to the outside via the air discharge system 18.

Further, the combustion exhaust gas after heating the reaction tube 2 with the combustion gas generated by burning the off gas by the burner 4 of the fuel reformer 1 is discharged to the outside through the exhaust gas discharge system 16. At this time, the combustion exhaust gas, the off gas, and the combustion air flow through the heat exchanger 10. Therefore, the off gas and the combustion air exchange heat with the combustion exhaust gas by the heat exchanger 10 and are preheated by the combustion exhaust gas.

Although both the off gas and the combustion air are preheated by the combustion exhaust gas by the heat exchanger 10 in FIG. 3, either the off gas or the combustion air may be preheated by the heat exchanger. Has been done.

By the way, the temperature of the reaction tube 2 heated by the combustion gas generated by the combustion by the burner 4 is controlled to a temperature suitable for the reforming raw material. This temperature control is performed by changing the flow rate of combustion air, that is, the air-fuel ratio.

[0012]

In the above fuel cell power generator, the temperature control of the reaction tube of the fuel reformer is performed by changing the flow rate of the combustion air supplied to the burner, that is, the air-fuel ratio. .. Therefore, when the balance of the heat supplied to the reaction tube is lost during a transition such as a load change of the fuel cell and the temperature of the reaction tube rises above a predetermined temperature, the reaction is increased by increasing the air-fuel ratio, that is, increasing the amount of combustion air. The temperature of the tube is lowered to control the temperature. For this reason, there is a drawback that the capacity of the blower for sending the combustion air must be large.

Further, since the combustion air is supplied to the burner via the heat exchanger, the influence on the temperature of the reaction tube becomes slow, and there is a drawback that the responsiveness is fast and stable temperature control cannot be performed.

An object of the present invention is to provide a temperature control device for a fuel cell power generator, which can reduce the capacity of a blower for delivering combustion air and can control the temperature of a reaction tube with a stable and fast response even during a transition such as a load change. Is to provide.

[0015]

In order to solve the above-mentioned problems, according to the present invention, a catalyst is filled with a fuel cell and a heat medium generated by burning off-gas from the fuel electrode of this cell with combustion air. A fuel reformer for heating the reaction tube to reform the reforming raw material flowing through the reaction tube into a gas rich in hydrogen, and at least one of off-gas and combustion air by the combustion exhaust gas discharged from the reformer. With a heater to preheat,
In a temperature control device for a fuel cell power generator that controls the temperature of a heated reaction tube, a bypass system including a flow rate adjusting valve and a temperature detector that detects the temperature of the reaction tube by offgas or combustion air bypassing the heater. And a control means for controlling the flow rate adjusting valve based on the deviation between the temperature detected by the detector and the target value of the temperature of the reaction tube.

[0016]

[Function] Bypassing the heater that preheats off-gas or combustion air by the combustion exhaust gas from the fuel reformer, and providing a bypass system equipped with a flow rate adjusting valve, the temperature of the reaction tube detected by the temperature detector and the reaction tube By controlling the flow rate adjusting valve from the deviation from the target value of the temperature suitable for reforming the reforming raw material flowing through, the flow rate of the bypass system that bypasses the heater is controlled by controlling the flow rate adjusting valve by the control means. Since the non-preheated off-gas or combustion air flowing through the heater is mixed with the pre-heated off-gas or combustion air and supplied to the burner, the amount of heat given to the heat medium generated by the combustion by the burner is changed, and Stable temperature control of the reaction tube with fast response can be performed even during transient load changes.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a fuel cell power generator including a temperature control device according to an embodiment of the present invention. In FIG. 1, the same parts as those in the conventional example of FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. 1 differs from the conventional example in that
Bypass system 21 that bypasses the heat exchanger 10 and branches and merges from the combustion air supply system 14 and that includes a flow rate adjustment valve 20.
And a temperature detector 22 for detecting the temperature of the reaction tube 2, and a temperature adjustment for controlling the flow rate adjusting valve 20 from the deviation between the temperature detected by this detector and a target value of a predetermined temperature suitable for reforming the reaction tube 2. And the container 23 is provided.

The temperature detector 22 may be installed in the furnace vessel near the reaction tube 2 instead of installing the detection end in the reaction tube 2.

With such a configuration, the amount of off gas corresponding to the load of the fuel cell 5 from the fuel electrode 7 of the fuel cell 5 is
It is preheated by the combustion exhaust gas passing through the off-gas exhaust system 13 and the exhaust gas exhaust system 16 in the heat exchanger 10 and supplied to the burner 4. On the other hand, the combustion air is supplied to the burner 4 through the combustion air supply system 14 including the bypass system 21 by the blower 15 with a combustion air amount controlled to a constant air-fuel ratio with respect to the amount of off gas supplied to the burner 4. .. At this time, the combustion air flowing through the heat exchanger 10 is preheated by the combustion exhaust gas,
The combustion air flowing through the bypass system 21 is not preheated. In this way, the off-gas supplied to the burner 4 is combusted by the combustion air supplied to the burner 4, and the combustion gas generated at this time heats the reaction tube 2 so that the reforming raw material flowing through the reaction tube 2 is hydrogen. Reform to rich gas.

At this time, the temperature of the reaction tube 2 is controlled to a temperature suitable for reforming the reforming raw material as follows. That is, the temperature of the reaction tube 2 is detected by the temperature detector 22, and a signal of the detected temperature is input to the temperature controller 23, which detects the detected temperature and a predetermined temperature suitable for reforming the reforming raw material of the reaction tube 2. The flow rate adjusting valve 20 is controlled based on the deviation from the target value of. Therefore, a part of the combustion air having a constant air-fuel ratio is partially flow-controlled valve 20.
The amount of combustion air controlled by the heat exchanger 10 flows through the bypass system 21 without being preheated, and is supplied to the burner 4 together with the remaining amount of combustion air preheated in the heat exchanger 10. The temperature of the tube 2 is controlled to a predetermined temperature.

Therefore, the temperature of the reaction tube 2 is set to the bypass system 2
Since the flow rate is controlled via the flow-controlled combustion air that is not preheated by the heat exchanger 10 via 1, the response is quick and stable, and the combustion air amount is controlled at a constant air-fuel ratio. The capacity of the blower may be smaller than the conventional one.

FIG. 2 is a system diagram of a fuel cell power generator having a temperature controller according to another embodiment of the present invention. Figure 2
In FIG. 1, the combustion air in FIG. 1 removes the bypass system 21 that bypasses the heat exchanger 10, the off gas bypasses the heat exchanger 10, and the bypass system 26 including the flow rate adjusting valve 25,
A temperature controller 27 for controlling the flow rate adjusting valve 25 is provided based on a deviation between a temperature detected by the temperature detector 22 of the reaction tube 2 and a target value of a predetermined temperature suitable for reforming the reforming raw material in the reaction tube 2. Is the same as that of FIG.

With this configuration, the signal of the temperature detected by the reaction tube 2 in the temperature detector 22 is input to the temperature controller 27, and the flow rate adjusting valve 25 is controlled by this controller to perform heat exchange. The off-gas that is not preheated without passing through the vessel 10 is flow-controlled and flows through the bypass system 26. The off-gas is mixed with the pre-heated off-gas via the heat exchanger 10 and is supplied to the burner 4 to be burned by the combustion air having a constant air-fuel ratio.
By heating, the temperature of the reaction tube 2 is controlled to a predetermined temperature through the flow rate-controlled off-gas that does not preheat and flows through the bypass system 26, and the same effect as described above can be obtained.

[0024]

As is clear from the above description, according to the present invention, the heater for preheating the off gas or the combustion air from the fuel cell by the combustion exhaust gas from the fuel reformer is bypassed, and the flow control valve is provided. By providing a bypass system and controlling the temperature of the reaction tube to a temperature suitable for reforming the reforming raw material so that part of the offgas or combustion air flows through the bypass system, the offgas supplied to the burner is When burning with a combustion air having a constant air-fuel ratio to this off-gas, a part of the off-gas or combustion air is not flow-controlled and is not preheated but is supplied to the burner through the bypass system and burned,
Since the reaction tube is heated by the heat medium generated at this time, the temperature of the reaction tube is controlled quickly and stably, and the combustion air is supplied to the burner at a constant air-fuel ratio. Has the effect of becoming smaller.

[Brief description of drawings]

FIG. 1 is a system diagram of a fuel cell power generator including a temperature control device according to an embodiment of the present invention.

FIG. 2 is a system diagram of a fuel cell power generator including a temperature control device according to another embodiment of the present invention.

FIG. 3 is a system diagram of a fuel cell power generator including a conventional temperature control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel reformer 2 Reaction tube 5 Fuel cell 10 Heat exchanger 20 Flow rate control valve 21 Bypass system 22 Temperature detector 23 Temperature controller 25 Flow rate control valve 26 Bypass system 27 Temperature controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motoichi Ikeda 2-6, Hisagi, Zushi City, Kanagawa Prefecture (6) B9 (72) Nobuhiro Iwasa 910-55 Katsuragi Town, Kishiwada City, Osaka Prefecture (72) Hiromasa Yoshida Aichi Prefecture 1-9-6 Oshikiri, Nishi-ku, Nagoya (72) Inventor Naonobu Yokoyama 1-1, Shinden Tanabe, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (1)

[Claims] 1. A fuel cell and a hydrogen-forming reforming material flowing through the reaction tube by heating a reaction tube filled with a catalyst by a heat medium generated by burning off-gas from the fuel electrode of the cell with combustion air. A fuel reformer for reforming into a rich gas and a heater for preheating at least one of off gas and combustion air by the combustion exhaust gas discharged from this reformer are provided, and the temperature of the heated reaction tube is controlled. In the temperature control device of the fuel cell power generation device, the off-gas or the combustion air bypasses the heater, the bypass system including the flow rate adjusting valve, the temperature detector that detects the temperature of the reaction tube, and the temperature detected by this detector And a control means for controlling the flow rate adjusting valve based on a deviation from a target value of the temperature of the reaction tube, the temperature control device of the fuel cell power generator.