JPS58165274A - Fuel cell - Google Patents

Abstract

PURPOSE:To improve operational stability of a fuel cell, by supplying fuel of methanol or the like and water independently of each other for a fuel electrode to hold a fuel ingredient and concentration of water in an anolyte in a steady state. CONSTITUTION:A methanol fuel cell is formed such that an air electrode 1 as the cathode, ion exchange film 2 and a methanol electrode 3 as the anode are closely attached in parallel to each other. If the cell is started, a controller 8 is operated to control opening and closing of a methanol supply valve 14 and water supply valve 13 and supply water and methanol into an anolyte 4 in accordance with temperature by a thermometer 9. In this way, fuel and water are supplied independently of each other, and concentration of water and fuel in the anolyte can be easily controlled to steadily hold an operational condition of the methanol fuel cell.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an acidic electrolyte fuel cell using liquid fuel, and more particularly to a method for supplying water and fuel to a sulfuric acid electrolyte methanol air fuel cell.

Methanol as a fuel is supplied to an anorite which circulates between a cell stacked sulfuric acid tank and a cell stacked sulfuric acid tank. The concentration of methanol is detected by a methanol sensor, and the amount of methanol that is consumed and reduced in concentration is supplied. The exhaust gas is discharged through a heat exchanger, and the condensed water is returned to the water tank.

As mentioned above, in the past, water supply was not controlled, so the water content in the anolite (electrolyte in the fuel chamber) decreased, making it difficult to adjust the sulfuric acid and methanol concentrations. -It was. In addition, the supply of anolyte is
With sulfuric acid, water supply is uncontrolled and η111
11□ An object of the present invention is to improve the stability of fuel cell operation by keeping the concentrations of fuel components and water in the anolite of the fuel cell constant.

The present invention 1) effectively stores the heat generated from the fuel cell; 2) prevents water emitted from the fuel chamber and air chamber from leaving the cell; and even if water escapes outside the system, the required amount of water is supplied to the fuel chamber. 3) quickly bring the cell into a steady state by separately supplying fuel and water; 4) maintain the temperature of the anolite in the cell at an optimal value by the above method.

1) Heat storage involves passing the exhaust gas through a heat exchanger and using the exhaust heat to heat the water or fuel in the water tank or fuel tank.

2) The amount of moisture emanating from the fuel chamber is small, and it is thought that it is usually contained in the sulfuric acid mist that comes out with carbon dioxide gas. On the other hand, from the air chamber, the reaction shown by the following equation proceeds at the air electrode and water is generated. 6 times as much H+ is generated when 1 mole of methanol reacts with 1 mole of water at the methane, 1, -l pole. That is, at the air electrode, 3 moles of water are generated with the reaction of 1 mole of methanol.

Furthermore, water passes through the ion exchange membrane that separates the methanol electrode and the air electrode together with hydrogen ions. The amount of permeation is 1 to 2 moles per 1 electrical charge. In other words, if 1 mole of methanol is ashed at the methanol electrode and 6 moles of hydrogen ions are generated, which reacts with oxygen at the air electrode and turns into water, then the water that moves to the air electrode with the hydrogen ions is ,
Since the amount of water is 6 to 12 moles, the amount of water coming out of the air chamber is about 9 to 15 moles. This water evaporates as water vapor, and if all this leaves the battery, it increases the surrounding humidity and depletes the moisture in the battery's anolite. Therefore, the exhaust gas from the air chamber is passed through a heat exchanger to recover water vapor and returned to the anorite or water tank for use.

3) When starting the battery, the anorite temperature is low, so the battery voltage is low, and as the temperature rises, the voltage increases. Therefore, when starting at voltage, by supplying a sufficient amount of fuel, the fuel in the anorite passes through an ion exchange membrane and reacts with oxygen at the air electrode, warming the battery with the heat generated. Once the temperature rises to steady operating temperature, water and fuel are supplied. If the temperature rises too much, supplying only water suppresses heat generation and lowers the temperature to a steady state. As described above, by independently supplying water and fuel to the battery, it is attempted to maintain the battery operating conditions as quickly as possible.

4) By combining the above operation control methods, the concentration and temperature of the anolyte component can be maintained at optimal operating conditions.

An embodiment of the present invention will be explained below with reference to FIG.

A methanol fuel cell has an air electrode as a cathode, an ion exchange membrane, and two. Methanol poles 3 as anodes are in close contact with each other in parallel. An anorite 4 is contained in the battery, and an air chamber 5 is located on the air electrode side. Air entering from the air port 6 is sent to the air chamber by the blower 10. At the air electrode, the exhaust gas which has consumed oxygen and contains water vapor enters the heat exchanger 15 together with carbon dioxide gas from the methanol electrode, and the water in the gas is condensed and returned to the anorite. At this time, the leached heat is transferred to the water in the water tank 11 and the methanol tank 12.
Used to heat the methanol inside.

The exhaust gas from which water has been removed is discharged outside the battery from the exhaust lower. When the battery is started, the control device 8 operates to control the opening and closing of the methanol supply pulp 14 and the water supply pulp 13 in accordance with the temperature measured by the thermometer 9, thereby supplying water and methanol into the anolite 4.

According to this embodiment, the moisture released from the air electrode is converted back into water by the heat exchanger and reused, thereby preventing water from being released outside the battery. Furthermore, since fuel and water are supplied independently, the concentrations of water and fuel in the anorite can be easily controlled.

The fuel supply amount is controlled by maintaining it at a constant level according to the instructions from the liquid level gauge 17.

According to the present invention, the operating conditions of the methanol fuel cell can be kept steady and the escape of water outside the cell can be minimized, so the time required for the cell to reach a stable state during operation is significantly reduced. ＜Also, it does not increase the humidity around the battery.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the configuration of the methanol fuel cell according to the present invention. Figure 2 shows the changes in anolyte temperature and the temperature control range (hatched lines) in the upper part, and the amount of methanol and water supplied over time in the lower part. FIG. DESCRIPTION OF SYMBOLS 1...Air electrode, 2...Ion exchange membrane, 3...Methanol electrode, 4...Anolyte, 5...Air chamber, 6...
... Air inlet, 7... Outlet, 8... Control device, 9
... thermometer, 10 ... blower 111 ... water tank, 12 ... methanol tank, 13 ... water supply pulp, 14 ... methanol supply pulp, 15 ... heat exchanger, 16...Battery body, chronograph circle (4 stakes) in the 1st port #20

Claims (1)

[Claims] 1. An acidic electrolyte fuel cell using liquid fuel such as methanol, formic acid, formalin, etc., characterized in that fuel such as methanol and water are supplied to the fuel electrode independently of each other. Fuel cell. 2. The fuel cell according to claim 1, wherein the pre-distribution water supply amount is determined by fuel consumption according to a preset fuel and water mixing ratio. 3. The fuel cell according to claim 2, wherein the water and fuel are filled in separate water tanks and fuel tanks, respectively, so that they do not mix with each other. 4. Exhaust gas discharged from the fuel chamber of the fuel cell passes through a water tank or a heat exchanger that also serves as a condenser connected to the fuel tank and is discharged to the outside of the fuel cell. Fuel cell as described in Section. 5. Claims characterized in that when the exhaust gas passes through a heat exchanger, water vapor, fuel vapor, and acid mist scattered from the electrolyte in the exhaust gas are liquefied and returned to the electrolyte in the fuel chamber. The fuel cell according to item 4. 6. The fuel cell according to claim 5, wherein the gas containing water vapor discharged from the air chamber passes through the heat exchanger, and the condensed water is returned to the water tank. 7. The fuel cell according to claim 6, wherein the exhaust gas discharged from the air chamber and the exhaust gas discharged from the fuel chamber are mixed and then passed through a heat exchanger. 8. The fuel cell according to claim 7, wherein the condensed water produced when the exhaust gas passes through a heat exchanger from the air chamber is poured into the electrolyte in the fuel chamber. 9. If the anorite in the fuel chamber is below the preset lower limit temperature, only fuel is supplied, and between the upper and lower temperature limits, fuel and water are supplied at a predetermined ratio, and when the temperature exceeds the upper limit temperature. 9. The fuel cell according to claim 8, wherein the fuel cell supplies only water.