JPH08287932A - Power generation method with heat utilization system - Google Patents

Abstract

PURPOSE: To attain power generation having heat utilization system with excellent energy efficiency by a small and simple device by using high purity hydrogen obtained by reforming hydrocarbon by steam for power generation of a fuel cell, using offgas as fuel of a reformer, and also using exhaust gas heat. CONSTITUTION: Hydrocarbon is reformed by steam by a membrane reformer 5 having a hydrogen separable permeable film 4 by supplying natural gas 7 and steam 8. Electric power is generated by supplying high purity hydrogen 11 separated from generated reformed gas by the permeable film 4 to a fuel cell 12. On the other hand, offgas 6 of the reformer 5 is supplied to a combustor 3, and is burnt by air from a blower 2, and is used as a heat source of the reformer 5 and a steam generator 10. Combustion exhaust gas 13 of the reformer 5 is also used as a heating source of a heating heat source or a warm water supply device or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined heat and power generation method using a hydrocarbon reformer and a fuel cell.

[0002]

2. Description of the Related Art As a cogeneration system for factories, offices or households, electric power is generated by a prime mover and a part of the electric power is supplied, and exhaust heat of the prime mover is generated by using exhaust gas. It supplies heat such as steam and hot water to improve the 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 device is also large-scale, noise and vibration are generated, and miniaturization is difficult.

On the other hand, research and development are being actively conducted toward the practical application of fuel cells as an urban power source that has extremely high power generation efficiency of 50% or more, low noise and vibration, and no fear of air pollution. . 150-23 for fuel cells
There are a phosphoric acid type that operates at 0 ° C., a solid polymer type that operates at 100 ° C. or lower, an alkaline type, and a molten carbonate type that operates at a temperature of 600 to 700 ° C. Among them, particularly in the solid polymer type which operates at 100 ° C. or lower, the catalyst such as platinum of the electrode is poisoned by CO, so that the CO concentration in the hydrogen-containing gas supplied to the fuel cell needs to be 10 ppm or lower. It is said that there is. Therefore, in order to use hydrogen produced by the 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 shift converter or a hydrogen purifier, and the CO content is It is necessary to have a high purity of 10 ppm or less, the process for that is complicated,
Moreover, a large amount of high-temperature heat energy is required, which is a problem in terms of cost.

By the way, recently, in the method for producing hydrogen by the steam reforming method, a combined technique of membrane separation has been proposed,
For example, US Pat. No. 5,229,102 describes a reformer which selectively permeates generated hydrogen by supplying hydrocarbon to a tubular porous ceramic membrane filled with a catalyst. ing. As a result, by removing the generated hydrogen out of the system, the equilibrium of the reforming reaction leans toward the hydrogen generating system.
Whereas a high temperature of 0 ° C was required, 300-700 ° C
It is described that the reforming can be performed at a relatively low temperature. Further, since it is possible to perform reforming at a relatively low temperature, it is described that a temperature about the exhaust gas of a gas turbine or a gas engine can be used as a reforming heat source. Aside from this, there is also known a technique in which a palladium-based thin film is used in combination with a reforming device, hydrogen obtained by reforming is made into high-purity hydrogen through the thin film, and this is supplied to a fuel cell.

[0005]

In this way, individual technologies such as the production of high-purity hydrogen by the reformer, power generation by the fuel cell, and some combinations of these technologies are tried in a fragmentary manner. Although efforts have been made to increase the power generation efficiency per fuel and the total thermal efficiency, it goes without saying that further improvement is required. Also, regarding the technology of attaching a palladium-based thin film to the latter reformer and supplying the obtained high-purity hydrogen to the fuel cell, the combustion heat of the offgas of the reformer is used as the heating source for the reforming, and after the above heating, It is not known that the exhaust heat of the combustion gas 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 permeable membrane with a fuel cell to make noise and the like relatively simple. The present invention has been completed on the idea that cogeneration power generation with excellent heat efficiency is possible.

That is, the present invention (1) supplies high-purity hydrogen obtained by steam reforming hydrocarbons to a fuel cell by a reformer having a hydrogen separation / permeable membrane (hereinafter referred to as a membrane) to generate electricity, Heat that heats the reformer by the combustion heat of the offgas of the reformer, and uses the exhaust heat of the combustion gas after heating the reformer as a heating heat source or a heating source of a hot water supply device. Cogeneration method,
(2) The method for combined heat and power generation according to (1) above, wherein the hydrogen separation / permeable membrane has a structure in which a thin film of a palladium-containing alloy is formed on the surface of an inorganic porous body, and (3) a fuel cell Is a polymer electrolyte fuel cell, which is the co-generation power generation method described in (1) or (2) above.

The reforming device adopted in the present invention has a membrane and has a high purity hydrogen, for example, a CO concentration of 10 p.
High-purity hydrogen of pm or less can be supplied, and reforming is 400 to 65
There is no particular limitation as long as it can be performed in the temperature range of 0 ° C. The reason why the reforming can be performed at a relatively low temperature as described above is that the chemical equilibrium is transferred to the hydrogen generation system as described above by taking out the hydrogen generated by the membrane to the outside of the system. Methane (CH ₄ ) which is the main component of natural gas
For example, the reforming reaction

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

A reformer equipped with such a membrane is usually called a membrane reactor, and various economical shapes have been devised in consideration of thermal efficiency. As the membrane, a membrane that selectively permeates hydrogen and has heat resistance is used. For example, a palladium-containing alloy film having a film thickness of 100 μm or more, or a palladium-containing alloy thin film having a film thickness of 50 μm or less is coated on an inorganic porous body, for example, a metal or ceramic porous body or a metal nonwoven fabric. As the inorganic porous body, a metal porous body is preferable from the viewpoint of workability such as sealing, impact resistance, hydrogen permeability and the like. The palladium-containing alloy is preferably palladium alone or an alloy containing 10% by weight or more of palladium. In addition to palladium, Group 10 elements such as Pt, Group 9 elements such as Rh and Ir, Group 8 elements such as Ru,
Those having a Group 11 element such as Cu, Ag and Au are preferable. Besides, an alloy film containing vanadium (V), for example, a film obtained by coating palladium on a Ni—Co—V alloy is used.

As a reforming catalyst for steam reforming hydrocarbons, metals of groups 8 to 10 (Fe, Co, Ni, Ru, P) are used.
(d, Pt, etc.) are preferable, and Ni, R
A catalyst supporting u, Rh or a NiO-containing catalyst is particularly preferable.

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

There is no particular limitation as a concrete reformer,
Known ones can be used. For example, Japanese Patent Laid-Open No. 2-3113
In Japanese Patent Laid-Open No. 01-151, a separation membrane having a hydrogen separation function is provided in a reaction tube filled with a catalyst, an outer cylinder is provided outside the reaction tube, and a reforming raw material is supplied into the reaction tube filled with the catalyst to generate hydrogen. A technique is described in which an inert gas (sweep gas) is caused to flow into the inside of the separation membrane, hydrogen that has permeated through the separation membrane is entrained in the sweep gas, taken out of the system, and supplied to the fuel cell. That is, the reforming section is a concentric triple tube, the intermediate layer is filled with a catalyst to produce hydrogen, and the hydrogen separated in the central portion of the tube through the separation membrane is accompanied by the sweep gas and discharged. The preferred reformer is as described above, but in addition to this, a ceramic membrane as described in the above-mentioned US Pat.

Examples of the fuel cell used in the present invention include the phosphoric acid type, the solid polymer type, the alkali type, the molten carbonate type, and the like. Among them, the solid polymer type fuel cell is particularly preferable. preferable.

In the present invention, high-purity hydrogen obtained by steam reforming hydrocarbons by a reformer having a membrane is supplied to a fuel cell to generate electricity, and the off-gas of the reformer is guided to a combustor. The reforming device itself is used as a heating source. Further, the exhaust gas of the combustion gas after heating the reformer is used to heat the heating and hot water supply device. The heating temperature of the reformer is controlled by controlling the combustion of offgas so that an appropriate reforming reaction occurs.

[0015]

【Example】

 [Embodiment 1] FIG. 1 shows the present invention adopted in this embodiment.
It is explanatory drawing of an example of the cogeneration power generation system device which concerns. Figure
1, the air 1 taken in is combustor by the blower 2.
Sent to 3. The combustor 3 has a membrane 4
The off gas 6 from the membrane reformer 5 is used as fuel.
Be paid. The combustion heat of the offgas 6 from the combustor 3 causes a membrane.
The ren reformer 5 is heated. Membrane reformer 5
Is supplied with natural gas 7 and steam 8. Steam 8
May be supplied from another steam source,
The combustion exhaust gas after heating the membrane reforming device 5
The steam generator 10 heats the water 9 to generate and supply it.
May be. In the membrane reforming device 5, the natural
When the reforming reaction is caused by the gas 7 and the steam 8,
The hydrogen produced is taken as high-purity hydrogen 11 by the membrane 4.
It is taken out, supplied to the fuel cell 12 and used for power generation.
On the other hand, unreacted natural gas, CO and C produced by the reforming reaction
O ₂Off gas 6 containing hydrogen, hydrogen, steam, etc.
Extracted from the Blaine reformer 5 and used as fuel for the combustor 3.
used. The high temperature combustion gas generated in the combustor 3
After heating the Blaine reformer 5 and the steam generator 10
The exhaust heat of the combustion exhaust gas 13 is used for heating.

[Embodiment 2] FIG. 2 is an explanatory view showing another example of the cogeneration system of the present invention used in this embodiment. Instead of using the combustion exhaust gas 13 of FIG. 1 for heating. It is used for heating the hot water supply device 14. Since the same parts as those in FIG. 1 are designated by the same reference numerals, the description thereof will be omitted. The water 9 is supplied to the hot water supply device 14, and the hot water 15
Is obtained. The low temperature combustion exhaust gas 16 after heating the hot water supply device 14 is released to the atmosphere.

[0017]

As described in detail above, according to the present invention, hydrocarbons can be reformed at a relatively low temperature as compared with conventional reformers, and high-purity hydrogen obtained from the reformers can be used for power generation efficiency. 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. Cogeneration with excellent thermal efficiency has become possible.

[Brief description of drawings]

FIG. 1 is an explanatory view of an example of an apparatus that can be used in the cogeneration power generation method according to the present invention.

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuto Kobayashi 4-6-22 Kannon Shinmachi, Hiroshima City, Hiroshima Prefecture Sanbishi Heavy Industries Ltd. Hiroshima Research Institute (72) Inventor Yoshiyuki Takeuchi 4, Kannon Shinmachi, Hiroshima City, Hiroshima Prefecture No. 6-22 Sanryo Heavy Industries Co., Ltd. Hiroshima Research Laboratory (72) Inventor Yoshimasa Fujimoto 4-6-22 Kannon Shinmachi, Hiroshima City, Hiroshima Prefecture Sanryo Heavy Industry Co., Ltd. Hiroshima Research Laboratory (72) Inventor Yoh Ota Zushi, Kanagawa Prefecture 7-7-31 Ichikuki (72) Inventor Shirasaki Yoshinori 2-29-14 Shibanishi, Kawaguchi City, Saitama Prefecture

Claims (3)

[Claims] 1. High-purity hydrogen obtained by steam reforming hydrocarbons by a reformer having a hydrogen separation and permeable membrane is supplied to a fuel cell to generate electricity, and the reforming device uses the combustion heat of off-gas to modify the hydrogen. A combined heat and power generation method, characterized in that the exhaust heat of the combustion gas after heating the quality device and heating the reforming device is used as a heating heat source or a heating source of a hot water supply device. 2. The combined heat and power generation method according to claim 1, wherein the hydrogen permeable membrane has a structure in which a thin film of a palladium-containing alloy is formed on the surface of an inorganic porous body. 3. The combined heat and power generation method according to claim 1, wherein the fuel cell is a polymer electrolyte fuel cell.