JPH08264200A - Piping part of fuel cell pressure vessel - Google Patents

Abstract

(57) [Abstract] [Purpose] To suppress the temperature drop of the supply gas and exhaust gas in the pressure vessel penetration part regardless of the heat source such as the pipe heater. [Structure] A double pipe penetrating portion 20 in which a fuel gas pipe 13 is passed through an oxidizing gas pipe 15 and a combustion exhaust gas pipe 14 are connected to an oxidizing exhaust gas pipe 1.
The pressure vessel 12 is penetrated by the double pipe penetrating portion 21 passing through the inside of the pressure vessel 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe penetrating portion of a pressure vessel of a molten carbonate fuel cell.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have characteristics that conventional power generators do not have, such as high efficiency and little impact on the environment, and they are attracting attention as a power generation system following hydropower, thermal power, and nuclear power. Is currently being researched and developed all over the world. The molten carbonate fuel cell utilizes the reverse reaction of electrolysis of water to convert chemical energy when hydrogen is produced from hydrogen and oxygen into electrical energy. Figure 2
Shows schematically this battery, in which an electrolyte plate 3 is sandwiched between an anode 1 made of porous Ni and a cathode 2 made of porous NiO, covered with grooved holders 4 and 5, and hydrogen is applied to the anode 1. Is sent as a combustion exhaust gas 7, an oxidizing gas mainly containing carbon dioxide gas and oxygen is sent to the cathode 2, and an oxidizing exhaust gas 9 is discharged. Electrolyte plate 3 intended to put carbonate into the pores of the porous body made of LiAlO _2, the operating temperature range of the fuel cell, the carbonate is the electrolyte solution through the CO _^2-3 melt. Also,
The electrolyte plate 3 is intended to store the carbonate for a long period of time and prevent mixing of the bipolar gas.

The electrode reaction of the molten carbonate fuel cell is as follows. Anode reaction ^{_{H 2 + CO 2- 3 → H}} 2 O + CO 2 + 2e cathode reaction _{CO 2 + 1 / 2O 2 +} 2e → CO 2- 3 net reaction _{H 2 + 1 / 2O 2 →} H 2 O carbon dioxide gas is consumed at the cathode, the anode Since the same amount is produced in the above, the reaction ends up producing water from hydrogen and oxygen.

Since about 80% of the fuel gas 6 is consumed in the cell reaction, the combustion exhaust gas 7 contains combustible gas, which is used to heat the natural gas containing water vapor and the fuel gas 6 using the catalyst. To generate. A part of the oxidizing exhaust gas is recirculated into the oxidizing gas 8, and a part of the oxidizing exhaust gas drives the turbine to rotate the compressor to supply compressed air to the oxidizing gas 8.

Fuel cells are stacked in multiple stages and housed in a pressure vessel. FIG. 3 shows a battery laminated with a pressure vessel and piping to the laminated battery. The laminated battery 11 is a pressure vessel 12.
It is stored inside and is normally operated at an operating pressure of about 5 kg / cm ² . A fuel gas pipe 13, a combustion exhaust gas pipe 14, an oxidizing gas pipe 15, an oxidizing exhaust gas pipe 16 and a control or instrumentation pipe 19 are connected to the laminated battery 11 by penetrating a lower portion of the pressure vessel 12. The fuel gas 6 and the oxidizing gas 8 are, for example,
It is supplied to the laminated battery 11 at around 600 ° C., undergoes a battery reaction, and becomes combustion exhaust gas 7 and oxidation exhaust gas 9 and is exhausted at around 670 ° C. For this reason, the inlet side pipes 13 and 15 maintain the temperature of the inlet side gases 6 and 8, so that the outlet side pipes 14 and 1
6 is heat-insulated 17 in order to effectively use the energy of the outlet gases 7 and 9. The flow rate of the oxidizing gas 8 is the fuel gas 6
Is much larger than the flow rate of the fuel gas pipe 13, and the diameter of the oxidizing gas pipe 15 is about 3 to 5 times larger than the diameter of the fuel gas pipe 13. For this reason, in the fuel gas pipe 13 having a small heat capacity, the temperature of the fuel gas 6 greatly decreases due to heat radiation.
Furthermore, the heat insulating material 17 is wound. On the other hand, since the oxidizing gas 8 has a large flow rate, it has a larger heat capacity and less temperature drop than that of heat radiation.

[0006]

Since the shape of the pipe penetration part under the pressure vessel 12 is complicated, and the analysis shows that the heat insulating effect is not so great even if the thickness of the heat insulating material is increased, the conventional fuel is not used. Although the pipe heater 18 prevents the temperature of the gas pipe 13 from lowering, it causes an increase in equipment and an increase in operating cost. Similarly, the combustion exhaust gas pipe 14 also has a large temperature drop due to heat dissipation at the pipe penetration portion. Since the combustion exhaust gas 7 is used as the combustion gas for the reformer that produces the fuel gas 6, it is possible to improve the efficiency of the entire apparatus by reducing the exhaust temperature and supplying the reformed gas to the reformer.

The present invention has been made in view of the above-mentioned problems, and suppresses the temperature drop of the passing gas due to heat radiation from the penetrating portion of the pressure vessel, regardless of the heat source such as the pipe heater, and simplifies the equipment. The purpose is to reduce operating costs.

[0008]

In order to achieve the above object, in the invention of claim 1, a fuel cell for reacting a fuel gas and an oxidizing gas to generate electricity and discharging combustion exhaust gas and oxidizing exhaust gas after the reaction is provided. There is a pressure container for storing the fuel cell, and the fuel gas pipe is a double pipe through the oxidizing gas pipe at a pipe penetration portion through which each gas pipe penetrates.

According to the second aspect of the present invention, there are provided a fuel cell for reacting a fuel gas and an oxidizing gas to generate electricity and discharging the combustion exhaust gas and the oxidizing exhaust gas after the reaction, and a pressure container for storing the fuel cell. A pipe for combustion exhaust gas passes through the pipe for oxidizing exhaust gas to form a double pipe at a pipe penetrating portion through which the pipe for each gas penetrates the pressure vessel.

In the third aspect of the present invention, the double pipe is fixed at one position where the inner pipe penetrates the outer pipe, and is connected at the other position via a bellows seal.

[0011]

According to the invention of claim 1, the structure of the pipe penetrating portion of the fuel gas pipe is a double pipe structure in which the fuel gas pipe is passed through the oxidizing gas pipe, and heat radiation from the oxidizing gas side is given to the fuel gas side. This makes it possible to suppress the temperature drop of the fuel gas. As a result, the temperature of the fuel gas becomes approximately the same as that of the oxidizing gas, which has a large heat capacity and a small temperature decrease. Since the oxidizing gas has a large capacity, there is little temperature drop even when the fuel gas is heated, and the temperature can be easily adjusted by recirculating the oxidizing exhaust gas having a higher temperature, so there is almost no temperature drop.

According to the second aspect of the present invention, the structure of the pipe penetration portion of the combustion exhaust gas pipe is a double pipe structure in which the combustion exhaust gas pipe is passed through the oxidation exhaust gas pipe, and heat radiation from the oxidation exhaust gas side is given to the combustion exhaust gas side. As a result, it is possible to suppress the temperature decrease of the combustion exhaust gas. Combustible gas contains combustible gas and is re-combusted in the reformer to generate fuel gas. Therefore, by suppressing the temperature decrease and combusting, the efficiency of the entire device is improved.

According to the third aspect of the invention, the inner pipe penetrates the outer pipe at a position where the double pipe is divided into a single pipe. By fixing both pipes at this one through position and connecting both pipes through the expandable bellows seal at the other through position, it is possible to absorb the difference in thermal expansion of each pipe and prevent the occurrence of thermal stress. it can.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. 1A and 1B show a configuration of an embodiment, FIG. 1A is a vertical sectional view, and FIG. 1B is a sectional view taken along line XX of FIG. The same symbols as those in FIGS. 2 and 3 represent the same contents. The laminated battery 11 is stored in the pressure container 12, and is pressurized to, for example, about 5 kg / cm ² during operation. The lower portion of the pressure vessel 12 is provided with the double pipe penetrating portions 20 and 21, and the double pipe penetrating portion 20 has the fuel gas pipe 13 penetrating the inside of the oxidizing gas pipe 15. The combustion exhaust gas pipe 14 penetrates through the oxidizing exhaust gas pipe 16. Among the positions where the inner pipes 13 and 14 of the double pipe penetrating portions 20 and 21 penetrate the outer pipes 15 and 16, the inner pipes 13 and 1 are located at the penetrating position 22 in the pressure vessel 12.
4 and the outer tubes 15 and 16 are fixed by welding or the like, and are joined via a bellows seal 23 at a penetration position outside the pressure vessel 12. As a result, the inner pipes 13 and 14 and the outer pipe 1
Even if there is a difference in thermal expansion between Nos. 5 and 16, no thermal stress is generated in each pipe. Outside the pressure vessel 12, the pipe portion and the bellows seal 23 that come into contact with the outside air are covered with a heat insulating material 17 to suppress heat radiation. The double pipe penetration part 20 shows an example in which the bellows seal 23 is provided in the vertical direction, and the double pipe penetration part 21 shows an example in which the bellows seal 23 is provided in the horizontal direction as shown in FIG.
A control and instrumentation pipe 19 is provided below the pressure vessel 12.

The fuel gas 6 and the oxidizing gas 8 are, for example, 60
It is planned to be supplied to the laminated battery 11 at around 0 ° C. Since the oxidant gas 8 has a large flow rate and a large heat capacity, the temperature of the oxidant gas 8 does not decrease much even if heat is dissipated, and the temperature decrease of the pipe penetration portion is about 10 ° C. When the double pipe penetrating portion 20 is adopted and the fuel gas pipe 13 is passed inside, the oxidizing gas pipe 1
5 has a pipe diameter 3 to 5 times that of the fuel gas pipe 15 and has a significantly large flow rate, so that even if the fuel gas 6 is heated, the temperature of the oxidizing gas 8 hardly decreases. On the other hand, the heating of the fuel gas 6 from the oxidizing gas 8 brings the temperature to almost the same temperature as the oxidizing gas 8. The oxidizing gas 8 reaches a temperature of around 670 ° C. due to the battery reaction and is discharged as the oxidizing exhaust gas 9, but a part of this is recirculated to the oxidizing gas 8, so the temperature can be adjusted and the supply temperature can be adjusted. By increasing the amount of decrease, the oxidizing gas 8 and the fuel gas 6 are supplied to the laminated battery 1 at around 600 ° C as planned.
1 can be supplied.

The combustion exhaust gas 7 is almost the same as the oxidation exhaust gas 6
It is discharged at around 70 ° C. In the case of a fuel cell, about 80% of the fuel gas 6 is used for the reaction, and about 20% is discharged as a combustion exhaust gas 7 containing a combustible gas. As the fuel gas 6, for example, steam is added to natural gas and heated with a catalyst in a reformer (not shown) to generate the fuel gas 6 mainly containing hydrogen. The combustion exhaust gas 7 is used as the heating gas. . Therefore, the combustion exhaust gas 7 is also supplied to the reformer so that the temperature does not drop at the pipe penetration portion. The double pipe penetrating portion 21 is provided for this purpose, and since the flow ratio of the combustion exhaust gas 7 and the oxidizing exhaust gas 9 is almost the same as the flow ratio of the combustion gas 6 and the oxidizing gas 8, the combustion exhaust gas 7 is also oxidized. The exhaust gas 9 is exhausted through the pipe penetrating portion at substantially the same temperature. This improves the combustion efficiency of the reformer and improves the efficiency of the fuel cell device.

The lower portion of the pressure vessel 12 has a fuel gas pipe 13,
Combustion exhaust gas pipe 14, oxidizing gas pipe 15, oxidizing exhaust gas pipe 16
In addition to the above four pipes, there are control pipes and instrumentation pipes 19, and it was difficult to properly arrange them due to the complicated arrangement of the pipes, but the four pipes became two, and the double pipe penetration parts 20, 21 Since the outer diameter of is not much different from the outer diameters of the conventional oxidizing gas pipe 15 and oxidizing exhaust gas pipe 16, the area that can be used for pipe penetration increases,
Appropriate arrangement of the control pipe and the instrumentation pipe 19 is possible. In the present embodiment, the fuel gas pipe 13 and the combustion exhaust gas pipe 14 are arranged in the oxidizing gas pipe 15 and the oxidizing exhaust gas pipe 16, but the reverse arrangement is also possible.

[0018]

As is apparent from the above description, according to the present invention, the fuel gas cell inlet is constituted by making the pipe penetration portion of the pressure container a double pipe penetration portion in which the fuel gas pipe is passed through the oxidizing gas pipe. The temperature drop in the pipe portion is reduced, and it is not necessary to provide a heat source such as a pipe heater, so that the device can be simplified and the operating cost can be reduced. Similarly, by making the combustion exhaust gas pipe a double pipe penetrating portion that passes through the oxidation exhaust gas pipe, the exhaust gas energy can be effectively utilized. Further, by providing such a double pipe penetrating portion, the gas supply and exhaust pipes are
Since the number of the pressure vessel penetrating portions is two, the penetrating area of the pressure vessel penetrating portion is reduced, and the control and instrumentation penetrating portions are easily arranged.

[Brief description of drawings]

FIG. 1 shows a configuration of an embodiment of the present invention, (A) is a vertical sectional view, and (B) is an XX sectional view of (A).

FIG. 2 is a schematic diagram showing a configuration of a molten carbonate fuel cell.

FIG. 3 is a view showing a conventional pressure vessel and a through pipe under the pressure vessel.

[Explanation of symbols]

 6 Fuel Gas 7 Combustion Exhaust Gas 8 Oxidation Gas 9 Oxidation Exhaust Gas 11 Laminated Battery 12 Pressure Vessel 13 Fuel Gas Pipe 14 Combustion Exhaust Gas Pipe 15 Oxidation Gas Pipe 16 Oxidation Exhaust Gas Pipe 17 Heat Insulating Material 18 Piping Heater 19 Control Piping, Instrumentation Piping 20, 21 Double Pipe Penetration Part 22 Inner Pipe Penetration Position in Pressure Vessel 23 Bellows Seal

Claims (3)

[Claims] 1. A fuel cell that reacts a fuel gas with an oxidizing gas to generate electricity and discharges a combustion exhaust gas and an oxidizing exhaust gas after the reaction, and a pressure container for storing the fuel cell. Pass the fuel gas pipe through the oxidizing gas pipe at the pipe penetrating portion where each gas pipe penetrates.
A pipe penetrating portion of a fuel cell pressure vessel, which is a heavy pipe. 2. A fuel cell that reacts a fuel gas with an oxidizing gas to generate electricity and discharges a combustion exhaust gas and an oxidizing exhaust gas after the reaction, and a pressure container for storing the fuel cell. A pipe penetrating portion of a fuel cell pressure vessel, characterized in that, in the pipe penetrating portion through which each gas pipe penetrates, the combustion exhaust gas pipe is passed through the oxidizing exhaust gas pipe to form a double pipe. 3. The double pipe is characterized in that both are fixed at one position where the inner pipe penetrates the outer pipe, and both are connected at the other position through a bellows seal. The pipe penetrating portion of the fuel cell pressure container according to 1 or 2.