Chemistry: electrical current producing apparatus – product – and – With pressure equalizing means for liquid immersion operation
Reexamination Certificate
1998-12-23
2001-02-06
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
With pressure equalizing means for liquid immersion operation
C429S006000
Reexamination Certificate
active
06183895
ABSTRACT:
TECHNICAL FILED
The present invention relates to a portable type fuel cell power generating system and, more particularly, to a portable type fuel cell power generating system capable of utilizing a commercially available butane gas cassette or pressure canister.
BACKGROUND ART
A fuel cell is known as a power generation system having a high energy efficiency, which generates electric power through electrochemical reaction of mainly hydrogen and oxygen, or hydrogen-rich gas obtained by reforming natural gas or the like and air, which are introduced to a fuel electrode and an oxygen electrode, respectively. Therefore, there has been proposed a portable type power generating system utilizing the fuel cell have been proposed.
Japanese Patent Kokai Publication No. 5-190196 proposes a portable power source wherein hydrogen-oxygen fuel cell is operated by using hydrogen absorbed in a hydrogen storage alloy in a pressure canister. This portable power source has such problems as the hydrogen storage alloy container is too expensive to be widely used, and the container is too heavy to be used in a portable power source.
Japanese Patent Kokai Publication No. 6-310166 also proposes a portable fuel cell power source comprising a fuel pressure canister filled with aqueous solution of methanol at a high pressure instead of hydrogen, a fuel reforming device which modifies the aqueous solution of methanol discharged from the fuel pressure canister into a gas consisting mainly of hydrogen, a fuel cell which generates electricity by using the hydrogen-rich gas as the fuel, and a cabinet that houses these components. This power source has such a problem that the fuel pressure container which contains the aqueous solution of methanol at a high pressure must have a high withstand pressure while such a pressure container is not suited to a portable apparatus and is not commercially available, resulting in an inconvenience for wide commercial applications.
For these reasons, portable power generation systems commercialized at present are still based on a gasoline engine, although it is a problem that small gasoline engine power generation systems of output power within several hundreds of watts have energy efficiency as low as 10% or less.
SUMMARY OF THE INVENTION
Therefore, there has been required to provide a portable fuel cell using a fuel cell of high energy efficiency and a commercially available portable butane gas pressure canister as the fuel source. But many problems must be solved before such an apparatus is realized.
(1) The temperature of a steam reforming process should be changed depending on kinds of gas to be steam-reformed in that the butane gas is preferably reformed at a high temperature not lower than 600° C., far higher than in the case of reforming methanol (220 to 270° C.). Although a method of reforming natural gases or hydrocarbon fuels may be applied, the method of reforming natural gas in a large plant cannot be applied as it is, so that it is particularly difficult to provide a small reforming device suitable for a portable apparatus.
(2) The butane gas pressure canister is subject to the influence of the ambient temperature, so that it is difficult to supply a predetermined amount of the butane gas to the reforming device in accordance to the load or to supply a predetermined amount of reformed gas to the fuel cell, thereby to generate a required amount of electric power.
(3) A solid polymer type fuel cell is more preferable than a phosphoric acid type fuel cell for the portable fuel cell. However, the solid polymer type fuel cell requires a decreased CO concentration of several tens ppm. in the reformed gas, which makes it a problem to strictly control the reforming device, particularly the CO oxidation section.
Therefore, it is a main object of the present invention to solve the above problems and to provide a portable fuel cell power generating system which uses a widely used butane gas pressure canister and has high energy efficiency.
The present invention has been completed on the basis of the invention “reforming device” filed separately (PCT/JP97/02265; Jun. 30, 1997), and provides a portable fuel cell power generating system, comprising:
a portable butane gas pressure canister containing a liquefied butane gas as the fuel;
a portable reforming device which generates a reformed gas including hydrogen gas by using a part of the butane gas supplied from the pressure canister as the fuel gas and causing a steam reforming reaction of the rest of the butane gas and water;
a portable fuel cell which generates electric power from the hydrogen gas included in the reformed gas and an oxygen gas included in the air;
a means for controlling the amount of the butane gas evaporated from the butane gas pressure canister; and
a butane gas flow control means installed in a flow path of supplying the butane gas from the butane gas pressure canister to the reforming device.
According to the present invention, as shown in the system operation diagram of
FIG. 9
, the butane gas from the portable pressure canister and water vapor are processed in the reforming device where the reformed gas consisting mainly of hydrogen is generated through steam reforming reaction of the butane gas, then hydrogen and oxygen are caused to react in the fuel cell to generate direct current, which may be converted to alternating current by an inverter and supplied to a load. According to the present invention, high energy efficiency of not less than 20% can be achieved even with a small power generation system having output power of several hundreds of watts. The energy efficiency is about three times as large as that of a gasoline engine power generator.
In a preferred embodiment of the present invention, a flow path from the butane gas pressure canister to the reforming device may comprise a passage for supplying the butane gas to be reformed and a passage for supplying the butane gas as the fuel used in the reforming device, so that a part of the butane gas is used as the fuel to heat the rest of the butane gas for reforming, thereby achieving a high reforming temperature.
In another preferred embodiment of the power generation system according to the present invention, continuous operation is enabled by providing two or more butane gas pressure canisters so that the gas can be supplied without interrupt when changing a pressure canister.
The butane gas pressure canister is provided with a means for controlling the amount of the butane gas evaporated. The butane gas therefrom can be evaporated by decreasing the pressure and/or heating. When the butane gas pressure canister is to be heated, the pressure canister is heated either directly or indirectly, with the heating means being selected from the group consisting of an electric heater, a means utilizing waste heat from the fuel cell and a means utilizing waste heat from the reforming device. Thus, it is made possible to control the pressure canister temperature and consequently the amount of the butane gas evaporated.
It is difficult to maintain the required amount of gas flow rate simply by controlling the amount of the butane gas evaporated. Therefore, it is preferable to provide the butane gas flow control means comprising a pressure regulator and a flow control valve.
The butane gas supplied from the butane gas pressure canister includes sulfur which is likely to cause degradation of a catalyst used in the reforming device and is therefore preferably removed. Thus, a desulfurizer is installed in the flow path through which the butane gas to be reformed is supplied in the preferred embodiment of the present invention. In order to increase the efficiency of desulfurization, it is preferable that the sulfur content be transformed to hydrogen sulfide which is then adsorbed in the desulfurizer. Accordingly, the desulfurizer is provided with a hydrogenation catalyst section for adding hydrogen to the butane gas to be reformed in the preferred embodiment of the present invention.
In the steam reforming reaction of the butane gas, a mixture of water vapo
Adachi Junji
Hashimoto Noboru
Kinugawa Kensaku
Kudo Hitoshi
Mizobuchi Manabu
Greenblum & Bernstein P.L.C.
Kalafut Stephen
Matsushita Electric & Works Ltd.
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