JP3591006B2 - Steam generator - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a steam generator that generates a small amount of superheated steam, and more particularly to a steam generator that injects steam in a degreasing step of a power generation pretreatment step of a molten carbonate fuel cell.
[0002]
[Prior art]
Molten carbonate fuel cells have features that are not found in conventional power generators, such as high efficiency and little impact on the environment, and have attracted attention as a power generation system following hydro, thermal and nuclear power. Is underway.
[0003]
FIG. 3 is a schematic structural view of a molten carbonate fuel cell. As shown in the figure, the fuel cell 12 includes an electrolyte plate 31, an anode 32 (electrode) and a cathode 33 (electrode) sandwiching the electrolyte plate 31, an anode gas flow path 34 for supplying the anode 32 with the anode gas 2, and a cathode 33. And a cathode gas flow path 35 for supplying the cathode gas 3 to the cathode. The electrolyte plate 31 is a flat plate made of sintered ceramic powder, and the carbonate is held in a gap between the plates in a high-temperature molten state. This production method includes a method in which the LiAlO ₂ powder of the support material and the powder of the carbonate are preliminarily mixed and molded, and a method in which only the LiAlO ₂ powder is molded and then impregnated with the carbonate. Is often used. The anode 32 and the cathode 33 are flat plates made of sintered metal powder, respectively, and sandwich the electrolyte plate 31 therebetween. A single battery (single cell) includes an anode 32, an electrolyte plate 31, and a cathode 33. The anode gas flow path 34 flows the anode gas 2 which has conductivity and contains hydrogen along the anode 32. The cathode gas channel 35 also has conductivity, and the cathode gas 3 containing oxygen and carbon dioxide gas flows along the cathode 33.
[0004]
After such a molten carbonate fuel cell is assembled in a factory and installed on site, a pretreatment process for generating power includes a degreasing process for the electrolyte plate 31 and an impregnation process for impregnating with a carbonate. The degreasing step is a step of removing organic substances such as a binder and a plasticizer used when forming the electrolyte plate 31. These organic substances remain in a carbonized state by sintering, and are removed by injecting steam.
[0005]
FIG. 4 shows a conventional steam generator used in a degreasing process of a small molten carbonate fuel cell having an output of about 1 to 10 kW. Pure water 45 is put in the tank 40, and a heater 41 for heating the pure water 45 is provided around the tank 40. An anode gas supply pipe 42 is provided at the bottom of the tank 40, and a vapor extraction pipe 43 is provided at the top, and is connected to the anode. The anode gas supply pipe 42 is provided with a flow meter 42a, and a pressure gauge 44 is provided at a position above the water level in the tank 40.
[0006]
When heated by the heater 41, saturated steam determined by the pressure in the tank 40 is generated. When the anode gas is supplied from the anode gas supply pipe 42, bubbles 46 are formed in the water, and the anode gas in the bubbles contains a certain amount of saturated steam in accordance with the pressure in the tank. Supplied to Thus, the amount of steam supplied to the anode can be determined by measuring the supply amount of the anode gas and the tank internal pressure. This device is often used because of its simple structure, high reliability and low cost.
[0007]
[Problems to be solved by the invention]
The steam generator shown in FIG. 4 is suitable for a small-scale molten carbonate fuel cell to be performed in a laboratory, but if it exceeds 100 kW, the required amount of steam increases, and it is possible to cope with this. Disappears. Also, the pressure loss when the anode gas passes through the water increases. Further, since the generated steam is a saturated steam, some of the steam condenses on the way and does not reach the anode.
[0008]
The present invention has been made in view of the above-described problems, and has as its object to provide a steam generator capable of generating a superheated steam that can cope with a required amount of steam.
[0009]
To achieve the above object, according to the present invention, a plurality of evaporating dishes having small holes and arranged at intervals in the vertical direction, a storage container for storing the evaporating dishes, and a penetrating through the storage container are provided. A water supply pipe for supplying water to an uppermost evaporating dish, a steam take-out pipe provided in the containment vessel, and a heating device provided around the containment vessel for heating the inside; provided in the evaporating dish The number of provided small holes decreases as the position goes down from the upper evaporating dish to the lower evaporating dish. The lowermost evaporating dish is not provided with the small holes, but is provided in the water supply pipe and supplied by the water supply pipe. A flow control valve that controls the amount of water so that water does not collect in the lowermost evaporating dish, and a flow meter that is provided in the water supply pipe and measures the amount of water supplied by the water supply pipe, is further provided. A steam generator is provided that features.
[0010]
Further, according to a preferred embodiment of the present invention, the steam extraction pipe is connected to an anode of a fuel cell, and steam obtained from the steam extraction pipe is used in a degreasing step of the fuel cell. The interior of the containment vessel is heated so that it does not condense until it reaches the anode.
[0012]
[Action]
According to the first aspect of the present invention, the inside of the storage container and each evaporating dish are heated by the heating device. Some of the water supplied to the uppermost evaporating dish evaporates there, and the other falls to the evaporating dish below the small hole, and similarly evaporates as it falls. Since the amount of water droplets falling through the small holes of the evaporating dish decreases as it goes down, the number of small holes decreases accordingly. The lowermost evaporating dish has no small holes, and the flow control valve controls the amount of water supplied by the water supply pipe so that water does not collect in the lowermost evaporating dish. Can evaporate all the water. The steam generated by setting the temperature in the storage container to the heating temperature of the generated steam becomes heated steam and is taken out from the steam extraction pipe. Also, if the supplied water is measured by a flow meter and the generated steam becomes heating steam and the heating temperature is set so as to reach the destination (for example, anode), the measured amount of steam can be measured. ) Can be supplied.
[0013]
According to the invention of claim 2, the steam extraction pipe is connected to the anode of the fuel cell, and the steam obtained from the steam extraction pipe is used in the degreasing step of the fuel cell, and the heating device causes the steam to reach the anode. Since the inside of the storage container is heated so as not to be condensed by the time, all the supplied pure water evaporates and becomes heated steam and reaches the anode. Thus, for example, by measuring the amount of water supplied to the steam generator by the flow meter, the measured value becomes the amount of water vapor supplied to the anode.
[0015]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same reference numerals are used for common parts. FIG. 1: shows the steam generator of an Example, (A) is sectional drawing, (B) is XX sectional drawing of (A). Reference numeral 20 denotes a steam generator. Reference numeral 21 denotes a storage container formed of a cylinder, a water supply pipe 22 penetrating the bottom inside, and evaporating dishes 24 attached at substantially equal intervals from a position slightly lower than the tip. The water supply pipe 22 passes through the center of each evaporating dish 24, and each evaporating dish 24 is provided with a number of small holes 25. The number of the small holes 25 decreases as going from the upper stage to the lower stage, and becomes zero at the lowermost stage. A steam extraction pipe 26 is provided at the top of the storage container 21. An electric heater 27 is provided around the storage container 21 to heat the inside of the storage container 21. Note that a gas or liquid burner can be used instead of the electric heater 27. The water supply pipe 22 is provided with a flow control valve 23 and a flow meter 28 for measuring the amount of water supply, and controls the flow control valve 23 so that the flow rate becomes a preset flow rate.
[0016]
FIG. 2 is a block diagram in which the steam generator 20 of the embodiment is attached to a fuel cell power generator. The steam generator 20 is connected to the anode A of the fuel cell 12. The connection time is a degreasing step before the start of power generation, and is removed after degreasing. The fuel cell power generator includes a reformer 10 for reforming a fuel gas 1 in which natural gas or the like is mixed with water vapor 8 into an anode gas 2 containing hydrogen, a cathode gas 3 containing carbon dioxide and oxygen, and an anode gas containing hydrogen. And an anode gas 2 produced in the reformer 10 is supplied to the fuel cell 12 and consumes most of the fuel cell 12 to become an anode exhaust gas 4, The gas for combustion is supplied to the combustion chamber Co of the reformer 10.
[0017]
In the reformer 10, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas 4 are burned in the combustion chamber Co to generate high-temperature combustion gas, and the combustion gas heats the reforming chamber Re. In the reforming chamber Re, the fuel gas 1 is reformed by the reforming catalyst to obtain the anode gas 2. The anode gas 2 is supplied to the anode A of the fuel cell 12. Further, after the combustion exhaust gas 5 that has exited the combustion chamber Co is cooled by the air preheater 13, the moisture is removed by the condenser 14 and the steam separator 15, and is pressurized by the low-temperature blower 16 and merged with the air 6. It becomes the cathode gas 3. The cathode gas 3 is circulated in the cathode C by the cathode circulation blower 19 to remove heat generated by the battery reaction. A portion of the cathode gas 3 reacts in the fuel cell 12 to become a high-temperature cathode exhaust gas 7, a portion of which is supplied to the combustion chamber Co of the reformer 10, and a portion of which is supplied to a turbine compressor for compressing the air 6. After the power is recovered by the machine 17, the heat energy is further recovered by the exhaust heat recovery steam generator 18 and discharged out of the system. The steam 8 generated by the exhaust heat recovery steam generator 18 is mixed with the natural gas to become the combustion gas 1.
[0018]
Next, the operation of the steam generator 20 shown in FIG. 1 will be described. The inside of the storage container 21 is overheated by the electric heater 27 and pure water is supplied from the water supply pipe 22. The supply amount is preferably such that water does not accumulate in the lowermost evaporating dish 24. Since the amount of supplied water is the amount of generated steam, the dimensions and the number of stages of the evaporating plates 24 are determined so that water does not accumulate in the lowermost evaporating plates 24 when the planned amount of water is supplied. I have. Thereby, the steam generated from each evaporating dish 24 becomes superheated steam in the storage container and is supplied to the anode A. The temperature of the superheating is set so as not to condense before reaching the anode A. The supply amount of water is measured by the flow meter 28. All of the supplied pure water evaporates and becomes superheated steam and reaches the anode A, so that the measured value of the water becomes the steam supply amount.
[0019]
【The invention's effect】
As is clear from the above description, in the present invention, a plurality of evaporating dishes are provided in the storage container at predetermined intervals in the vertical direction, and the evaporating dishes are provided with small holes so that water can be transmitted to each evaporating dish. Since the storage container is heated by supplying water to the upper evaporating dish to generate superheated steam, superheated steam can be generated according to the supply amount of water.
[Brief description of the drawings]
1A and 1B show a steam generator according to an embodiment, in which FIG. 1A is a cross-sectional view, and FIG. 1B is a cross-sectional view of FIG.
FIG. 2 is a block diagram showing a case where the steam generator of the embodiment is connected to a fuel cell power generator.
FIG. 3 is a diagram showing a schematic structure of a molten carbonate fuel cell.
FIG. 4 is a diagram showing a conventional small-scale steam generator.
[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 Steam 10 Reformer 12 Fuel cell 13 Air preheater 14 Condenser 15 Steam separator 16 Low temperature blower 17 Turbine compressor 18 Exhaust Heat recovery steam generator 19 Cathode circulation blower 20 Steam generator 21 Storage container 22 Water supply pipe 23 Flow control valve 24 Evaporating dish 25 Small hole 26 Steam extraction pipe 27 Electric heater 28 Flow meter Co Combustion chamber Re Reforming chamber

Claims (2)

A plurality of evaporating dishes having small holes and arranged at intervals in the vertical direction, a storage container for storing the evaporation dishes, and a water supply pipe penetrating the storage container and supplying water to an uppermost evaporating dish And, a steam extraction pipe provided in the containment vessel, and a heating device provided around the containment vessel and heating the inside ,
The number of small holes provided in the evaporating dish is reduced as the number of the small holes goes down from the upper evaporating dish to the lower evaporating dish, and the lowermost evaporating dish is not provided with the small holes,
A flow control valve that is provided in the water supply pipe and controls the amount of water supplied by the water supply pipe so that water does not accumulate in the lowermost evaporating dish.
A steam generator , further comprising: a flow meter provided in the water supply pipe, for measuring an amount of water supplied by the water supply pipe . The steam extraction pipe is connected to an anode of a fuel cell, and steam obtained from the steam extraction pipe is used in a degreasing step of the fuel cell.
  The steam generator according to claim 1, wherein the heating device heats the inside of the storage container so that the steam does not condense before reaching the anode.

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