JP3297246B2 - Cogeneration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cogeneration system using a hydrocarbon reformer and a fuel cell.

[0002]

2. Description of the Related Art As a cogeneration system for factories, offices, or homes, electric power is generated by a prime mover to supply a part of the electric power, and exhaust heat of the prime mover is generated by using exhaust gas. It supplies heat such as steam or hot water to improve overall thermal efficiency. However, since this uses a prime mover such as a steam turbine, a gas turbine, a diesel engine, or a gas engine, the apparatus is large-scale, and noise and vibration are generated, and miniaturization is difficult.

[0003] On the other hand, research and development are being actively conducted for the practical use of fuel cells as an urban power supply having an extremely high power generation efficiency of 50% or more, low noise and vibration and no fear of air pollution. . 150 to 23 for fuel cell
There are a phosphoric acid type operating at 0 ° C., a solid polymer type operating at 100 ° C. or less, an alkali type, a molten carbonate type operating at an operating temperature of 600 to 700 ° C., and the like. Among them, in particular, in a solid polymer type that operates at 100 ° C. or less, since the catalyst such as platinum of the electrode is poisoned by CO, it is necessary to reduce the CO concentration in the hydrogen-containing gas supplied to the fuel cell to 10 ppm or less. It is said that there is. For this reason, in order to use hydrogen produced by a conventional steam reforming method of hydrocarbons or alcohols as a fuel gas for a fuel cell, the crude hydrogen is further purified by a CO converter or a hydrogen purifier to reduce the CO content. It is necessary to have a high purity of 10 ppm or less, the process is complicated,
In addition, a large amount of high-temperature heat energy is required, which has been a problem in terms of cost.

[0004] Recently, in the method of producing hydrogen by the steam reforming method, a combined use technique of membrane separation has been proposed.
For example, U.S. Pat. No. 5,229,102 describes a reformer that selectively permeates generated hydrogen by supplying hydrocarbons to a tubular porous ceramic membrane filled with a catalyst. ing. As a result, by removing the generated hydrogen to the outside of the system, the equilibrium of the reforming reaction is inclined toward the hydrogen generation system.
While a high temperature of 0 ° C. was required, 300-700 ° C.
It is described that it can be reformed at a relatively low temperature. Further, it is described that since reforming can be performed at a relatively low temperature, a temperature about the exhaust gas of a gas turbine or a gas engine can be used as a reforming heat source. Separately from this, there is also known a technique in which a palladium-based thin film is used in combination with a reformer, hydrogen obtained by the reforming is converted into high-purity hydrogen through the thin film, and the hydrogen is supplied to a fuel cell.

[0005]

As described above, individual technologies such as production of high-purity hydrogen by a reformer, and power generation by a fuel cell and a combination of some of these technologies have been tried in a fragmentary manner. Efforts have been made to increase power generation efficiency per fuel and overall thermal efficiency, but it goes without saying that further improvements are required. In addition, regarding the technology of attaching a palladium-based thin film to the latter reformer and supplying the resulting high-purity hydrogen to the fuel cell, the heat of combustion of the off-gas of the reformer is used as a heating source for the reforming, and further after the heating. It is not known that the waste heat of the combustion gas of the present invention is effectively used as a heat source for heating or hot water supply.

[0006]

In view of the current state of the art, the present inventors have combined a reformer having a hydrogen separation and permeable membrane with a fuel cell to provide a relatively simple apparatus and reduce noise and the like. The inventors have conceived that it is possible to perform cogeneration with excellent heat efficiency and have completed the present invention.

That is, the present invention relates to a package having a film thickness of 100 μm or more.
A hydrogen separation and permeable membrane consisting of a radium-containing alloy membrane, or
Palladium-containing alloy thin film with a thickness of 50 μm or less
High-purity hydrogen obtained by steam reforming hydrocarbons by a reformer having a hydrogen separation and permeable membrane having a structure coated on the body is supplied to a polymer electrolyte fuel cell to generate power, and the reformer is The reformer is heated by the combustion heat of the off-gas and steam is supplied to the reformer.
Heating the steam generator, the reformer and the steam
A cogeneration how, characterized by using a combustion gas exhaust heat after heating the generator as a heat source for heating the heat source or hot water supply.

The reforming apparatus used in the present invention has a structure described later.
Has a configuration of the membrane, can supply high-purity hydrogen, for example CO concentration less high purity hydrogen 10 ppm, reforming 40
It can be performed in a temperature range of 0 to 650 ° C. The reason that the reforming can be performed at a relatively low temperature is because the chemical equilibrium described above is transferred to the hydrogen generation system by extracting hydrogen generated by the membrane out of the system. Taking the case of methane (CH ₄ ), which is the main component of natural gas, as an example, the reforming reaction

Embedded image In the conventional reforming method, the reaction zone temperature is set to about 800 ° C.
However, by utilizing the membrane to achieve the same conversion, temperatures between 400 and 65
It can be achieved at 0 ° C.

A reforming apparatus having such a membrane is usually called a membrane reactor, and various economical shapes are devised in consideration of thermal efficiency. In membrane selectively permeable to hydrogen as a membrane, and heat resistance Yusuke that thickness 100μm or more palladium-containing alloy film or film thickness 50μm following palladium-containing alloy thin film of an inorganic porous material, for example metal or ceramic, A material coated on a porous material or a metal nonwoven fabric is used. As the inorganic porous body, a metal porous body is preferable from the viewpoints of workability of a seal or the like, impact resistance, hydrogen permeability, and the like.
The palladium-containing alloy is preferably one containing palladium alone or 10% by weight or more,
In addition to palladium, those containing a Group 10 element such as Pt, a Group 9 element such as Rh and Ir, a Group 8 element such as Ru, and a Group 11 element such as Cu, Ag, and Au are preferable. In addition, an alloy film containing vanadium (V), for example, Ni—Co—V
A film in which an alloy is coated with palladium is used.

[0010] As a reforming catalyst for steam reforming hydrocarbons, a group 8 to 10 metal (Fe, Co, Ni, Ru, P
d, Pt, etc.), and Ni, R
Catalysts supporting u, Rh or NiO-containing catalysts are particularly preferred.

As the hydrocarbon used as the reforming raw material, those having about 1 to 10 carbon atoms can be used, including light hydrocarbons such as natural gas containing methane as a main component, LPG, city gas, and naphtha. However, it is particularly preferable to use natural gas.

There are no particular restrictions on the specific reformer,
Known ones can be used. For example, Japanese Unexamined Patent Publication No.
No. 01 discloses a separation membrane having a hydrogen separation function inside a reaction tube filled with a catalyst, and an outer cylinder provided outside the reaction tube to supply a reforming raw material into the reaction tube filled with a catalyst to generate hydrogen. A technique is described in which an inert gas (sweep gas) flows into the inside of the separation membrane, and hydrogen permeated through the separation membrane is taken out of the system together with the sweep gas and supplied to the fuel cell. That is, the reforming unit is a concentric triple tube, a middle layer is filled with a catalyst to produce hydrogen, and the hydrogen separated at the center of the tube through the separation membrane is discharged together with the sweep gas .

[0013] As the fuel cell used in the present invention, a polymer electrolyte fuel cell in Japanese <br/> are preferred.

In the present invention, high-purity hydrogen obtained by steam reforming a hydrocarbon by a reformer having the above-mentioned specific structure is supplied to a polymer electrolyte fuel cell to generate electric power. At the same time, the off-gas of the reformer is guided to a combustor for combustion, and the combustion heat is used as a heating source of the reformer itself. Furthermore, the heating and the hot water supply device are heated by using the exhaust heat of the combustion gas after heating the reforming device. The heating temperature of the reformer is controlled by controlling off-gas combustion so that an appropriate reforming reaction occurs.

FIG . 1 is an explanatory diagram of an example of a cogeneration system according to the present invention. In FIG. 1, taken air 1 is sent into a combustor 3 by a blower 2. An off-gas 6 from a membrane reformer 5 having a membrane 4 is supplied to the combustor 3 as fuel. The membrane reformer 5 is heated by the heat of combustion of the off-gas 6 by the combustor 3. The natural gas 7 and the steam 8 are supplied to the membrane reformer 5. Although the steam 8 may be supplied from another steam source, as shown in FIG. 1, water 9 is supplied to the steam generator 10 by the combustion exhaust gas after heating the membrane reformer 5.
Is preferably generated by heating . In the membrane reformer 5, the natural gas 7 and the steam 8
The reforming reaction takes place, and the resulting hydrogen is extracted as high-purity hydrogen 11 by the membrane 4 and
2 and used for power generation. On the other hand, off-gas 6 containing unreacted natural gas, CO, CO ₂ , hydrogen, steam, and the like generated in the reforming reaction is taken out from the membrane reforming device 5 and used as fuel for the combustor 3. The exhaust heat of the combustion exhaust gas 13 after heating the membrane reformer 5 and the steam generator 10 with the high-temperature combustion gas generated in the combustor 3 is used for heating.

FIG . 2 is an explanatory diagram showing another example of the cogeneration system according to the present invention.
3 is used for heating the hot water supply device 14 instead of using it for heating. 1 are denoted by the same reference numerals, and description thereof is omitted. Water 9 is supplied to the hot water supply device 14, and hot water 15 is obtained. Hot water supply device 14
The low-temperature combustion exhaust gas 16 after heating is released to the atmosphere.

[0017]

As described above in detail, according to the present invention, it is possible to reform hydrocarbons at a relatively low temperature as compared with a conventional reformer, and to convert high-purity hydrogen obtained from the reformer into power generation efficiency. In addition to supplying fuel to a good fuel cell, the reformer itself is heated by the combustion of off-gas from the reformer, and the exhaust heat is used as a heating source for heating or hot water, making it a compact and simple device. Cogeneration with excellent thermal efficiency has become possible.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of an apparatus that can be used in a cogeneration method according to the present invention.

FIG. 2 is an explanatory diagram of an example of another device that can be used in the cogeneration method according to the present invention.

Continued on the front page (72) Inventor Kazuto Kobayashi 4-622 Kannon Shinmachi, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Center (72) Inventor Yoshiyuki Takeuchi 4-622 Kannon Shinmachi, Hiroshima City, Hiroshima Prefecture Hiroshima Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Yoshimasa Fujimoto 4-6-22 Kannon Shinmachi, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Center (72) Inventor Yoshu 7-7 Hisagi, Zushi City, Kanagawa Prefecture 31 (72) Inventor Yoshinori Shirasakizaki 2-29-14 Shibanishi, Kawaguchi City, Saitama Prefecture (56) References JP-A-4-321502 (JP, A) JP-A-5-159793 (JP, A) Kaihei 5-290865 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 8/00, 8/04, 8/06

Claims (1)

(57) [Claims] 1. A palladium-containing alloy having a thickness of 100 μm or more.
Hydrogen separation / permeable membrane consisting of gold membrane, or 50 μm or less
The following palladium-containing alloy thin film is coated on inorganic porous material.
Hydrocarbons of high purity hydrogen obtained by steam reformed by the reforming device having a hydrogen separation permeable membrane grayed structure, solid
The power is supplied to the polymer fuel cell to generate power, and the reformer is heated by the heat of combustion of the off-gas of the reformer.
To generate steam to supply steam to the reformer
A method of co-generation, comprising: using a combustion gas exhaust heat after heating a reformer and heating the reformer and the steam generator as a heating heat source or a heating source of a hot water supply device.