JPH0982351A - Phosphoric acid type fuel cell power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely operate a device by calculating a temperature rise in a cooling pipe from outputs of temperature sensors on the refrigerant inlet and outlet sides, sending out an abnormal signal when its value exceeds a reference value in a no-load operation condition, and detecting a phosphoric acid lacking condition caused in a single cell in its early stages. SOLUTION: A refrigerant side inlet temperature sensor 2 to detect a temperature of a refrigerant flowing to the inlet side of a refrigerant common pipe 24 and a refrigerant outlet temperature sensor 3 to detect a temperature of the refrigerant flowing to the outlet side of a refrigerant discharge pipe 25, are incorporated as an abnormality detecting means to detect a phosphoric acid lacking condition of an electrolyte layer. An abnormality detecting circuit 4 is arranged to generate an abnormal signal when its value exceeds a reference value in a no-load operation condition by calculating a temperature rise in the refrigerant in a cooling pipe by inputting outputs of the two temperature sensors 2 and 3. A phosphoric acid quantity of an electrolyte layer lacks, and when reaction gas leaks by passing through a matrix, the refrigerant flowing in the cooling pipe is heated, and a temperature rise in the refrigerant exceeds the reference value, and the abnormality detecting circuit 4 generates an abnormal signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphoric acid fuel cell power generator using phosphoric acid as an electrolyte, and more particularly to a power generator having a function of monitoring a shortage of phosphoric acid.

[0002]

2. Description of the Related Art In a phosphoric acid fuel cell power generator, a fuel cell stack is constructed by stacking single cells in which an electrolyte layer holding phosphoric acid in a matrix is sandwiched between a fuel electrode and an air electrode. It is a device that supplies hydrogen to the electrode as a fuel gas and oxygen to the air electrode as an oxidant gas to generate electricity by an electrochemical reaction.

FIG. 2 is an exploded perspective view showing an example of a fuel cell stack of a phosphoric acid fuel cell power generator. An electrolyte layer 11 made of a matrix holding phosphoric acid is attached to a fuel electrode 12
The unit cell 10 is formed by being sandwiched by the air electrode 13 and the air electrode 13. The fuel electrode 12 is constituted by closely adhering a fuel electrode catalyst layer to a ribbed fuel electrode base material provided with a groove for passing a fuel gas,
Further, the air electrode 13 is constituted by closely adhering an air electrode catalyst layer to a ribbed air electrode base material having a groove for passing air in a direction orthogonal to the fuel gas. The unit cell 10 thus formed is laminated with the gas non-diffusing separator 14 interposed, and the cooling plate 20 is incorporated every time a plurality of layers are laminated to form a fuel cell laminate. A plurality of cooling pipes 21 are embedded in the cooling plate 20, and cooling water is passed through the cooling pipes 21 as a refrigerant to cool the fuel cell stack, thereby removing heat generated by the electrochemical reaction and operating the same. The temperature is maintained at a predetermined temperature.

FIG. 3 is a perspective view showing the structure of the cooling plate 20. A plurality of cooling pipes 21 having the same pipe diameter are embedded in parallel in a rectangular cooling plate 20, and the ends of the cooling pipes 21 are attached to a refrigerant supply pipe 24, respectively, and are connected to a refrigerant supply header 22 and a refrigerant discharge. It is attached to the pipe 25 and is connected to the refrigerant discharge header 23. Therefore,
The cooling water sent as the refrigerant is guided from the refrigerant supply pipe 24 to the refrigerant supply header 22 and then the plurality of cooling pipes 21.
Are almost evenly diverted to cool the cooling plate 20, are collected in the refrigerant discharge header 23, and are discharged from the refrigerant discharge pipe 25.

A fuel gas and air supply manifold and a discharge manifold are installed on each side surface of the fuel cell stack constructed as described above, and the operating temperature is set to 1
If the fuel gas and air are allowed to flow while maintaining the temperature at about 90 ° C., an electrochemical reaction occurs in each single cell 10 and the power generation operation is continued.

[0006]

In the phosphoric acid fuel cell power generator using the fuel cell stack constructed as described above, the vapor of water produced by the electrochemical reaction mainly generated in the air electrode 13 of each single cell 10 When the gas permeates the air electrode base material and is discharged into the groove for air flow, phosphoric acid scatters along with this, and the phosphoric acid in the electrolyte layer 11 gradually decreases.
As the power generation operation progresses, the situation will eventually lead to a shortage of phosphoric acid. When the phosphoric acid in the electrolyte layer 11 is insufficient, the activity of the electrode catalyst is reduced, so that the power generation voltage at the time of high load is greatly reduced, and when the phosphoric acid is insufficiently deficient, the phosphoric acid is retained in the portion. Since current concentrates and current density increases, there is a risk of overload and damage.
Further, when the phosphoric acid deficiency further progresses, the reaction gas leaks through the matrix of the electrolyte layer 11 due to the pressure difference between the fuel gas and the air, and a direct reaction occurs between the reaction gases, resulting in a fuel cell stack. Risk of serious damage.

In order to avoid the occurrence of such serious damage, it is necessary to detect the phosphoric acid deficiency state at an early stage and take a countermeasure. For this reason, in the conventional phosphoric acid fuel cell power generator, the degree of decrease in the generated voltage at high load is monitored, the degree of decrease in the no-load voltage at startup is monitored, or a differential pressure is applied to the single cell from the outside. A means for detecting the shortage of phosphoric acid by measuring the amount of gas permeation is adopted.

However, in the above-mentioned means, in the case of a fuel cell stack having a large number of stacked unit cells, it is difficult to detect due to a decrease in voltage unless phosphoric acid is insufficient in a considerable number of unit cells. Therefore, there is a risk of overlooking the occurrence of a local shortage, and there is a high risk that a considerable amount of damage has already occurred at the time of detection. Further, in the means of, since a differential pressure is applied, it becomes a severe condition for a single cell where the phosphoric acid is locally insufficient, and the phosphoric acid remaining in the portion where the phosphoric acid is insufficient due to the applied differential pressure is There is a danger that it will blow through.

The present invention has been made in consideration of the drawbacks of the prior art as described above, and an object of the present invention is to provide a means for early detection of a phosphoric acid deficiency state occurring in a single cell, which enables safe driving. An object is to provide a phosphoric acid fuel cell power generator.

[0010]

In order to achieve the above-mentioned object, in the present invention, a plurality of unit cells each having a matrix in which an electrolyte layer holding phosphoric acid is sandwiched between a fuel electrode and an air electrode are provided. A fuel cell stack, which is configured by stacking a cooling plate in between, is provided. Fuel gas is supplied to the fuel electrode and oxidant gas is supplied to the air electrode to generate electricity by an electrochemical reaction, and heat generated by the power generation. In a phosphoric acid fuel cell power generator that removes heat by passing a refrigerant through a cooling pipe embedded in a cooling plate,
The coolant supply pipe that supplies the coolant to the cooling pipe is equipped with a coolant inlet side temperature sensor that detects the temperature of the flowing coolant, and the temperature of the coolant flowing through the coolant discharge pipe that discharges the coolant from the cooling pipe is detected. It is equipped with a refrigerant outlet side temperature sensor to further calculate the temperature rise of the refrigerant in the cooling pipe by inputting the output of the refrigerant inlet side temperature sensor and the refrigerant outlet side temperature sensor, and the value is the reference value in the no-load operation state. An abnormality detection circuit that emits an abnormality signal when exceeding the limit shall be provided.

When the phosphoric acid fuel cell power generator is constructed as described above, no electrochemical reaction occurs when there is no load, and therefore no heat is generated. Therefore, if the fuel cell stack is normal, the refrigerant flowing through the cooling pipe embedded in the cooling plate is discharged without being heated, and therefore the temperature of the refrigerant detected by the temperature sensor on the refrigerant inlet side and the temperature on the refrigerant outlet side are detected. The temperature of the refrigerant detected by the sensor is almost the same. On the other hand, when phosphoric acid in the electrolyte layer becomes insufficient and the reaction gas leaks after permeating the matrix, the reaction gas directly reacts in the single cell and generates heat. The refrigerant flowing through the pipe is heated, and the temperature of the refrigerant detected by the refrigerant outlet side temperature sensor becomes higher than the temperature of the refrigerant detected by the refrigerant inlet side temperature sensor. Therefore, in the no-load operation state, the temperature rise of the refrigerant is calculated from the outputs of the refrigerant inlet side temperature sensor and the refrigerant outlet side temperature sensor, and the lack of phosphoric acid in the electrolyte layer is known by comparing the value with the reference value. It will be.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a basic configuration diagram of an abnormality detecting means showing an embodiment of a phosphoric acid fuel cell power generator of the present invention. In the figure, the fuel cell stack 1 schematically shown is constructed by stacking single cells using phosphoric acid in an electrolyte layer with a separator interposed therebetween, and incorporating a cooling plate 20. Cooling plate 2 incorporated in fuel cell stack 1
0 has a plurality of cooling pipes 21 embedded therein,
One ends of these cooling pipes 21 are connected to a coolant supply pipe 24 via a coolant supply header 22 and the other ends are connected to a coolant discharge pipe 25 via a coolant discharge header 23.
Further, in the present configuration, the refrigerant inlet side temperature sensor 2 for detecting the temperature of the refrigerant flowing to the inlet side of the refrigerant supply pipe 24 serves as the abnormality detecting means for detecting the phosphoric acid deficiency state of the electrolyte layer. The refrigerant outlet side temperature sensor 3 for detecting the temperature of the refrigerant flowing to the outlet side of the discharge pipe 25 is incorporated, and further, the output of these two temperature sensors is input to calculate the temperature rise of the refrigerant in the cooling pipe, An abnormality detection circuit 4 is provided which issues an abnormality signal when the value exceeds a reference value in a no-load operation state.

According to this structure, when the amount of phosphoric acid in the electrolyte layer is normal, no heat is generated inside the fuel cell stack 1 and the refrigerant is not heated in the no-load operation state. Since the temperature rise of the refrigerant obtained from the outputs of the two temperature sensors is kept below the reference value, the abnormality detection circuit 4 does not issue an abnormality signal. When the amount of phosphoric acid in the electrolyte layer is insufficient and the reaction gas permeates the matrix and leaks, the reaction gas directly reacts in the single cell to generate heat, so the refrigerant flowing through the cooling pipe does not flow even under no load. Be heated. Therefore, the temperature rise of the refrigerant obtained from the outputs of the two temperature sensors exceeds the reference value, and the abnormality detection circuit 4
Emits an abnormal signal, so that it is easy to know that a situation of insufficient phosphoric acid has occurred.

In the above configuration example, by incorporating the refrigerant outlet side temperature sensor 3 at the outlet side of the refrigerant discharge pipe 25 to detect the temperature of the discharged refrigerant, the unit cells of the fuel cell stack 1 are detected. Although the method of collectively detecting the situation of phosphoric acid shortage is used, if the refrigerant outlet side temperature sensor 3 is incorporated in the outlet portion of the refrigerant discharge header 23 connected to the cooling pipe 21 of each cooling plate 20, This is more effective because the location where the phosphoric acid deficiency occurs is detected separately.

[0015]

As described above, in the present invention, a single cell in which an electrolyte layer in which phosphoric acid is held in a matrix is sandwiched between a fuel electrode and an air electrode is laminated with a plurality of layers interposed by cooling plates. And a fuel gas are supplied to the fuel electrode and an oxidant gas is supplied to the air electrode,
In a phosphoric acid fuel cell power generator that generates electricity by an electrochemical reaction and passes the heat generated by power generation through a cooling pipe embedded in a cooling plate to remove heat, a refrigerant supply pipe that supplies the refrigerant to the cooling pipe A refrigerant inlet side temperature sensor for detecting the temperature of the flowing refrigerant is provided, and a refrigerant outlet pipe for discharging the refrigerant from the cooling pipe is provided with a refrigerant outlet side temperature sensor for detecting the temperature of the flowing refrigerant. An abnormality detection circuit that calculates the temperature rise of the refrigerant in the cooling pipe using the output of the temperature sensor on the side of the refrigerant and the temperature sensor on the outlet side of the refrigerant and outputs an abnormality signal when the value exceeds the reference value in the no-load operation state Therefore, the phosphoric acid deficiency state that occurs in the single cell can be detected early without stopping the power generation operation, and it is possible to obtain the phosphoric acid fuel cell power generator that can be operated safely.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of abnormality detecting means showing an embodiment of a phosphoric acid fuel cell power generator of the present invention.

FIG. 2 is an exploded perspective view showing an example of a fuel cell stack of a phosphoric acid fuel cell power generator.

3 is a perspective view showing a configuration of a cooling plate incorporated in the fuel cell stack of FIG.

[Explanation of symbols]

 1 Fuel Cell Stack 2 Refrigerant Inlet Side Temperature Sensor 3 Refrigerant Outlet Side Temperature Sensor 4 Abnormality Detection Circuit 10 Single Cell 11 Electrolyte Layer 12 Fuel Electrode 13 Air Electrode 14 Separator 20 Cooling Plate 21 Cooling Pipe 22 Refrigerant Supply Header 23 For Refrigerant Discharge Header 24 Refrigerant supply pipe 25 Refrigerant discharge pipe

Claims (1)

[Claims] 1. A fuel cell laminate comprising a plurality of unit cells each having an electrolyte layer in which phosphoric acid is held in a matrix sandwiched between a fuel electrode and an air electrode, with a plurality of layers sandwiching a cooling plate. A fuel gas is supplied to the fuel electrode and an oxidant gas is supplied to the air electrode to generate electricity by an electrochemical reaction, and heat generated by the power generation is passed through a refrigerant through a cooling pipe embedded in a cooling plate to remove heat. In the acid fuel cell power generator, the refrigerant supply pipe for supplying the refrigerant to the cooling pipe is provided with a refrigerant inlet side temperature sensor for detecting the temperature of the flowing refrigerant, and the refrigerant discharge pipe for discharging the refrigerant from the cooling pipe. In the, provided with a refrigerant outlet side temperature sensor for detecting the temperature of the refrigerant flowing through, further, the temperature rise of the refrigerant in the cooling pipe is calculated by inputting the output of the refrigerant inlet side temperature sensor and the refrigerant outlet side temperature sensor, Value is no load Phosphoric acid fuel cell power generation apparatus characterized by comprising an abnormality detection circuit for emitting an abnormality signal when it exceeds the reference value at.