JPH08293314A - Fuel cell generating device - Google Patents

Abstract

PURPOSE: To automatically switch to a spare fuel to stabilize the power supply by using the cooling water of a fuel cell body as a heating source to evaporate liquid fuel, when the supply of city gas for the fuel of a reformer is interrupted, and supplying it to the reformer. CONSTITUTION: City gas is introduced through a feed valve 1, mixed with steam in an ejector 7 through a hydrodesulfurizing device 6, and supplied to a reformer 10. The reforming gas rich in hydrogen obtained there is supplied to the hydrogen electrode 13 of a fuel cell body 12, and the air from a compressor 15 is supplied to an air electrode 16. In the above fuel cell generating device, when the supply of city gas is interrupted by an accident, a liquefied propane 23 from a storage tank 33 is supplied through a pump 32, evaporated by an evaporator 22, and supplied through a feed valve 25. At the that time, at least a part of the cooling water sent from a steam separator 8 to a cell cooler 18 is used as the evaporating heat source of the evaporator 22. The supply stop of city gas is preferably detected by a pressure detector 31 to automatically operate a three-way valve 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention automatically switches the operation to liquid fuel which is a preliminary fuel to continuously operate the fuel cell main body even if the gas fuel which is constantly used is shut off, and the stable electric power is supplied. The present invention relates to a fuel cell power generator configured to supply.

[0002]

2. Description of the Related Art As a fuel for a fuel cell power generator using a phosphoric acid fuel cell, a gaseous fuel containing methane as a main component such as natural gas or city gas, or methanol, liquefied propane gas or the like convenient for storage is used. Liquid fuel is used.
Each of these fuels undergoes steam reforming in a reformer to be converted into hydrogen-rich gas, and this hydrogen-rich gas is supplied to a phosphoric acid fuel cell for power generation. Before supplying to the phosphoric acid fuel cell, carbon monoxide in the hydrogen-rich gas is converted into carbon dioxide by the carbon monoxide shift converter. By the way, when a gaseous fuel, for example, city gas, is used as the fuel for the fuel cell power generator, there is a problem that the fuel cell power generator stops if the city gas supply is cut off due to some trouble such as an earthquake. . Therefore, a method is conceivable in which a liquid fuel convenient for storage is stored as a backup fuel, and when the supply of city gas is interrupted, the fuel cell power generator is continuously operated with this liquid fuel.

FIG. 3 is a system configuration diagram of a fuel cell power generator capable of switching from city gas to liquefied propane gas as a backup fuel. That is, as shown in FIG. 3, during normal operation, the city gas supply valve 1 is opened to introduce the city gas from the city gas supply line 2a to the fuel supply line 2b, and the reformed gas line 4 on the outlet side of the low temperature shift transformer 3 is introduced. It is supplied to the ejector 7 via the hydrodesulfurization device 6 together with a part of the reformed gas supplied from the recirculation line 5 branched from.

On the other hand, steam is supplied to the ejector 7 from the separator 8 through the steam line 9, and the steam and city gas are mixed in the ejector 7 at an appropriate ratio and the mixed gas is supplied to the reformer 10. . The mixed gas supplied into the reformer 10 undergoes the reforming reaction on the heated catalyst,
It is supplied to the low temperature shift transformer 3.

In the reformer 10, a reforming reaction represented by the chemical formula CH ₄ + H ₂ O → 3H ₂ + CO proceeds in the internal catalyst layer, and in the low temperature shift shift converter 3, the internal catalyst layer has the chemical formula. The carbon monoxide shift reaction represented by CO + H ₂ O → H ₂ + CO ₂ proceeds. The reformed gas exiting the low temperature shift transformer 3 is supplied to the hydrogen electrode 13 of the fuel cell main body 12 via the hydrogen electrode supply line 11.

In the fuel cell main body 12, a part of hydrogen in the reformed gas is used, and the cell exhaust gas containing the remaining hydrogen is supplied to the burner of the reformer 10 through the burner line 14. The burner burns hydrogen in the exhaust gas of the battery with the air supplied from the air compressor 15 to heat the reformer 10. Further, from the air compressor 15, the fuel cell body 1
Air is also sent to the second oxygen electrode 16.

On the other hand, the cooling water for the fuel cell body 12 is supplied from the separator 8 to the cell cooler 18 via the cell cooling water pump 17.
Is supplied to. The cooling water discharged from the battery cooler 18 is returned to the separator 8 via the heat exchanger 20.

The above is the operation during city gas operation. When the pressure in the city gas supply line 2a falls below a predetermined value, the city gas pressure detector 21 provided in this city gas supply line 2a When a decrease in gas pressure is detected, liquefied propane gas supply pump 32 supplies liquefied propane gas 23 from liquefied propane gas storage tank 33, and liquefied propane gas 23 stored in liquefied propane gas vaporizer 22 is heated by electric heater 24. Then, the vaporized gas vaporized is introduced from the liquefied propane gas supply line 41 to the fuel supply line 2b by opening the liquefied propane gas supply valve 25. At this time, the city gas supply valve 1 on the city gas supply line 2a side is closed at the same time when the liquefied propane gas supply valve 25 is opened. In the figure, 23a indicates a liquid surface of liquefied propane gas, 26 indicates a safety valve, and 27 indicates a reformer fuel exhaust gas.

[0009]

However, the vaporizing method of liquefied propane gas is uneconomical because the heat source depends entirely on the outside of the fuel cell power generator because only the electric heater is used. Then, in order to prevent the city gas supply from being stopped when it cannot happen, the liquefied propane gas is always kept in a reformable gas state. Therefore, even if the liquefied propane gas is not used as a fuel, the electric heater 2
It was necessary to keep 4 working and keep it above the vaporization temperature of liquefied propane gas, and the electricity charges for this were not negligible. Further, when the fuel cell is operated with liquid propane gas, about 3% of the power generation output is consumed by the electric heater 24 that vaporizes the liquefied propane gas.

The present invention has been made in view of the above circumstances. When the supply of gas fuel such as city gas is cut off, vapor of liquid fuel such as liquefied propane gas is supplied as an alternative fuel to continue power generation. An object of the present invention is to provide a fuel cell power generation device that can economically vaporize the liquid fuel when it is necessary to do so.

[0011]

In order to achieve the above-mentioned object, a fuel cell power generator of the present invention is formed by stacking cells having a hydrogen electrode and an oxygen electrode as a pair, has a cooler, and has a cooling water. It is a fuel cell power generator composed of a fuel cell body that is cooled by a fuel cell and a reformer that reforms fuel to produce a hydrogen-rich reformed gas that is supplied to the fuel cell body. Supply a gaseous fuel such as city gas to the reformer to produce a hydrogen-rich reformed gas, and supply the hydrogen-rich reformed gas to the fuel cell main body for operation. When the supply of hydrogen is cut off, the liquid fuel supplied from the liquid fuel storage tank is heated by the vaporizer to be vaporized and supplied to the reformer to form a hydrogen-rich reformed gas. Supply gas to the fuel cell body to operate In the fuel cell power generator, the heat exchanger for vaporizing the liquid fuel is provided with a heat exchanger, and at least a part of cooling water for the fuel cell main body is supplied to the heat exchanger. It is characterized in that the vaporizer of liquid fuel is heated.

Further, the fuel cell power generator of the present invention has a structure in which cells having a hydrogen electrode and an oxygen electrode are laminated, has a cooler, and is cooled by cooling water. And a reformer for reforming the fuel to produce a hydrogen-rich reformed gas to be supplied to the fuel cell body, and a reformer for the fuel gas to be supplied to the reformer or to the hydrogen-rich reformed gas supplied to the fuel electrode of the fuel cell body. A secondary cooling water system configured to flow secondary cooling water into the heat exchanger system so as to adjust the temperature condition of the quality gas or the temperature condition of the cell cooling water to be supplied to the fuel cell. It is a fuel cell power generation device that constantly supplies gas fuel such as city gas to a reformer to reform it to create a hydrogen-rich reformed gas, and supplies this hydrogen-rich reformed gas to the fuel cell body. Operation is performed to supply gas fuel such as city gas. When is cut off, the liquid fuel supplied from the liquid fuel storage tank is heated by the vaporizer to be vaporized and supplied to the reformer to form a hydrogen-rich reformed gas. In a fuel cell power generator configured to be supplied to the fuel cell main body for operation, a heat exchanger is provided in the vaporizer as a heating means for vaporizing the liquid fuel, and the heat exchanger is connected to the heat exchanger. Heat exchange between the secondary cooling water by using the battery cooling water or the reformer combustion exhaust gas or air electrode exhaust gas, or by using two or three of the battery cooling water, the reformer combustion exhaust gas and the air electrode at the same time. At least a part of the secondary cooling water heated by the above is supplied to heat the vaporizer of the liquid fuel.

Further, the carburetor of the fuel cell power generator of the present invention is characterized by having a structure in which heating by heat exchange and heating by an electric heater are used together. Also, the fuel cell power generator of the present invention is provided with a flow rate control means for cooling water passing through the heat exchanger provided in the vaporizer, and controls the flow rate of the cooling water to vaporize the liquid fuel. It is characterized by controlling the quantity.

Further, the fuel cell power generator of the present invention is characterized in that the supply amount of the liquid fuel to the vaporizer is controlled by an amount representative of the state inside the vaporizer. Further, the fuel cell power generator of the present invention is characterized in that at least one of a liquid level, a gas temperature, and a gas pressure is used as an amount representative of the state inside the vaporizer.

[0015]

With the above-mentioned means, the present invention constantly supplies the gaseous fuel to the reformer for reforming, supplies the obtained hydrogen-rich gas to the fuel cell main body to generate electricity, and When the supply is interrupted, the liquid fuel vaporizer vaporizes the liquid fuel, the gas of the liquid fuel is supplied to the reformer for reforming, and the obtained hydrogen-rich gas is supplied to the fuel cell body. In a fuel cell power generator that supplies power to generate power, a heating unit that heats the vaporizer to vaporize the liquefied propane gas is configured by a heat exchanger, and cooling water in the fuel cell power generator is provided in the heat exchanger. It is used to heat the vaporizer.

In such a fuel cell power generator,
During operation with normal gas fuel, the liquid fuel that is the preliminary fuel is vaporized by a heat exchanger that uses the exhaust heat from the cooling water system in the fuel cell power generator in advance and placed in a standby state, which hinders the supply of gas fuel. When it is detected, the vaporized liquid fuel is supplied to the reformer instead, so that it is possible to continue the power generation device of the fuel cell main body and effectively use the exhaust heat from the power generation device. It is economical because it does.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel cell power generator according to the present invention will be described below with reference to the drawings by using city gas as a gas fuel and liquefied propane gas as a liquid fuel as an example. FIG. 1 is a configuration diagram of a fuel cell power generator showing an embodiment of the present invention in which cell cooling water is used as a heat source of a vaporizer. The same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. , Here, only different points will be described.

In this embodiment, as shown in FIG. 1, the liquefied propane gas vaporizer 22 is covered with a heat insulating material, and the liquefied propane gas vaporizer outlet is provided in the upper part of the inside to heat the liquefied propane gas. A heat exchanger 31 for The liquefied propane gas vaporizer 22 is adapted to drive the liquefied propane gas supply pump 32 to supply the liquefied propane gas 23 from the liquefied propane gas storage tank 33 when the supply of city gas is interrupted. In this case, the liquefied propane gas supply pump 32 performs intermittent operation, and when the liquefied propane gas liquid level 23a of the liquefied propane gas vaporizer 22 is lower than the middle portion of the container, the liquefied propane gas supply pump 32 starts operating and the liquefied propane gas liquid level 23a reaches a predetermined level. Stop at height.

Further, the heat exchanger 31 provided in the liquefied propane gas vaporizer 22 is constantly heated by hot water supplied from the outlet of the cell cooler 18 of the fuel cell main body 12 through the three-way valve 34 and the hot water line 35. It has become so.
In this case, the hot water that has heated the heat exchanger 31 is the three-way valve 34.
It is further branched and merged with the hot water that has undergone heat exchange by the heat exchanger 20 and is guided to the separator 8. Further, vaporized liquefied propane gas is supplied to the inlet of the liquefied propane gas supply valve 25. City gas supply valve 1 and liquefied propane gas supply valve 2
5 is switched by a switching command from a control device (not shown).

Further, the vaporized gas temperature or pressure of the liquefied propane gas vaporizer 22 is measured (not shown), and the flow rate of the three-way valve 34 is controlled by a controller (not shown) so that the measured temperature or pressure becomes a predetermined value. The liquefied propane gas supply pump 32 may be operated by controlling the vaporization amount appropriately.

Next, the operation of the fuel cell power generator configured as described above will be described. Normal city gas operation is similar to that described in the conventional example, but in this case, the heat exchanger 31 mounted on the liquefied propane gas vaporizer 22 is
From the outlet of the battery cooler 18 of the fuel cell body 12 to the three-way valve 3
4. Battery cooling water of about 170 ° C. is supplied through the hot water line 35, and the liquefied propane gas vaporizer 22 is constantly heated. During normal city gas operation, the liquefied propane gas vaporizer 22 holds a part of the liquefied propane gas 23 in a gaseous state, and the city gas supply line 2
Only when the pressure of a decreases, the liquefied propane gas supply valve 25 is opened to supply the propane gas to the inlet side of the hydrodesulfurization device 6, while the city gas supply valve 1 is closed to switch the fuel. As a result, when the level of the liquefied propane gas vaporizer 22 falls below a predetermined value, the liquefied propane gas supply pump 32 is activated to supply the liquefied propane gas vaporizer 22 with the liquefied propane gas 23.

The heat exchanger 31 provided in the constant liquefied propane gas vaporizer 22 is connected to the cell cooler 1 of the fuel cell body 12.
Since liquefied propane gas is vaporized by supplying the battery cooling water from the outlet of 8 through the three-way valve 34 and the hot water line 35, the liquefied propane gas can be supplied in the vaporized state at the same time when the city gas is shut off, and the liquefied propane gas is also liquefied. Propane gas supply pump 3
Even if the liquefied propane gas is supplied from the liquefied propane gas storage tank 33 to the liquefied propane gas vaporizer 22 through 2, the liquefied propane gas 23 can be vaporized in a short time. And as a heat source for vaporizing liquefied propane gas,
Since the exhaust heat from the power generator is used, there is no need to supply heat from the outside, and economical operation becomes possible.

Further, since the periphery of the liquefied propane gas vaporizer 22 is covered with a heat insulating material, the liquefied propane gas vaporizer 2
The amount of heat radiated from 2 is small and can always be maintained at a constant temperature.

The heat exchanger 3 provided in the vaporizer 22
1 has been described by supplying the cell cooling water from the three-way valve 34 from the outlet of the cell cooler 18 of the fuel cell main body 12, this three-way valve 34 has the same effect even at the inlet of the cell main body 12. Can be satisfied.

FIG. 2 is a constitutional view of a fuel cell power generator showing another embodiment of the present invention in which the secondary cooling water of about 80 ° C. is used as the heat source of the vaporizer. 2, those parts which are the same as those corresponding parts in FIG. 1 are designated by the same reference numerals, and a description thereof will be omitted. The secondary cooling water circulation pump 38 sends out the secondary cooling water, and recovers the heat of a necessary portion in the fuel cell power generator. In FIG. 2, heat exchangers 36 and 37 are shown as typical examples. This heat exchanger 3
The positions of 6 and 37 have various variations depending on the system configuration of the fuel cell power generator. FIG. 2 showing the present embodiment.
Shows an example in which they are arranged in the cell cooling water system and the fuel processing system. The secondary cooling water that has cooled the necessary part is used as the heat exchanger 39.
Then, the collected heat is radiated, and the secondary cooling water circulation pump 3 is used again.
It is configured to circulate at 8. Liquefied propane gas vaporizer 2 by branching at least part of this secondary cooling water system
Liquefied propane gas is vaporized by guiding it to the heat exchanger 31 provided in the No. 2 unit. The secondary cooling water is supplied to the hot water line 35 by the three-way valve 34. The flow rate of the secondary cooling water is three-way valve 34
The temperature is adjusted according to need and is circulated by the secondary cooling water circulation pump 38 through the heat exchanger 39.

Since the temperature required for vaporizing the liquefied propane gas in the vaporizer 22 is about 50 to 55 ° C., the vaporizer 22
As the heat source of the liquefied propane gas, the carburetor 22 is heated to the temperature required for vaporizing the liquefied propane gas whether the battery cooling water is used as shown in FIG. 1 or the secondary cooling water is used as shown in FIG. It is possible to warm. However, considering the exhaust heat utilization of the fuel cell, the cell cooling water at 170 ° C. is taken out as high temperature water or steam and used for cooling and heating rather than being used as the heat source of the vaporizer, and the temperature is low as shown in FIG. It is advantageous to use the secondary cooling water having a low utility value as the heat source of the carburetor 22 because the overall efficiency of the fuel cell combining heat and electricity is improved.

The carburetor of the fuel cell power generator of the above embodiment may have a structure in which heating by heat exchange and heating by an electric heater are used together. Further, the fuel cell power generator of the above embodiment is provided with a flow rate control means for cooling water passing through the heat exchanger provided in the vaporizer, and controls the flow rate of the cooling water to control the vaporized gas amount of the liquid fuel. can do.

Further, in the fuel cell power generator of the above embodiment, the supply amount of the liquid fuel to the vaporizer can be controlled by an amount representative of the state inside the vaporizer. Further, in the fuel cell power generator of the above embodiment, at least one of the liquid level, the gas temperature and the gas pressure can be used as the quantity representative of the state inside the carburetor.

As described above, an apparatus that has conventionally used the electric power generated by the liquefied propane gas to vaporize the liquefied propane gas uses the liquefied propane to partially or completely dissipate the plant exhaust heat originally dissipated in the atmosphere. By using the gas for gasification, it has become possible to effectively utilize the power generation output.

The effect is that the output at the transmission end as a generator is improved by about 3%, and the efficiency at the transmission end is about 1% (L
HV base) will be improved. Moreover, when secondary cooling water, which has conventionally been low in utility value and could only be used for hot water supply or heating, is used, the exhaust heat utilization efficiency is approximately 3%, and the electric power / exhaust heat utilization overall efficiency is approximately 1% (whichever is Also has an improved LHV base).

[0031]

As described above, according to the present invention, the supply of gas fuel such as city gas is cut off, and vapor of liquid fuel such as liquefied propane gas is supplied as an alternative fuel to continue power generation. When it does not occur, it is possible to provide a fuel cell power generation device that can economically vaporize the liquid fuel.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a first embodiment of a fuel cell power generator according to the present invention.

FIG. 2 is a system configuration diagram showing a second embodiment of the fuel cell power generator according to the present invention.

FIG. 3 is a system configuration diagram showing an example of a conventional fuel cell power generator.

[Explanation of symbols]

 1 ... City gas supply valve 2a ... City gas supply line 2b ... Fuel supply line 3 ... Low temperature shift transformer 4 ... Reformed gas line 5 ... Recirculation line 6 ... Hydrodesulfurization device 7 ... Ejector 8 ... Separator 9 ... Steam Line 10 ... Reformer 11 ... Hydrogen electrode supply line 12 ... Fuel cell main body 13 ... Hydrogen electrode 14 ... Burner line 15 ... Air compressor 16 ... Oxygen electrode 17 ... Battery cooling water pump 18 ... Battery cooler 20 ... Heat exchanger 21 ... City gas pressure detector 22 ... Liquefied propane gas vaporizer 23 ... Liquefied propane gas 23a ... Liquefied propane gas liquid level 24 ... Electric heater 25 ... Liquefied propane gas supply valve 26 ... Safety valve 27 ... Reformer fuel exhaust gas 31 ... Heat Exchanger 32 ... Liquefied propane gas supply pump 33 ... Liquefied propane gas storage tank 34 ... Three-way valve 35 ... Hot water line 36 ... Heat exchanger 37 ... Heat exchange Exchanger 38 ... Secondary cooling water circulation pump 39 ... Heat exchanger 41 ... Liquefied propane gas supply line

Front Page Continuation (72) Inventor Kizen Katsuhisa 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Day Telegraph and Telephone Corporation (72) Inventor Isao Abe 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Date (72) Inventor Tetsuo Ohashi 2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Inside Keihin Works, Toshiba Corporation (72) Inventor Hiroshi Naka Naka 1-1, Shibaura, Minato-ku, Tokyo Stocks Company Toshiba Head Office

Claims (6)

[Claims] 1. A fuel cell body comprising a stack of cells having a hydrogen electrode and an oxygen electrode as a pair, having a cooler and being cooled by cooling water, and a fuel obtained by reforming the fuel. A fuel cell power generator that is composed of a reformer that produces a hydrogen-rich reformed gas that is supplied to the battery body.It is a hydrogen-rich reformed gas that is normally supplied to the reformer with gaseous fuel such as city gas. The hydrogen-rich reformed gas is supplied to the fuel cell main body for operation, and when the supply of the gaseous fuel such as the city gas is cut off, the liquid fuel supplied from the liquid fuel storage tank is vaporized. Fuel cell power generator for heating and vaporizing in a reactor to supply the reformer with hydrogen-rich reformed gas and supplying the hydrogen-rich reformed gas to the fuel cell main body for operation In, as a heating means for vaporizing the liquid fuel A fuel cell power generation system characterized in that a heat exchanger is provided in the vaporizer and at least a part of cooling water for the fuel cell main body is supplied to the heat exchanger to heat the vaporizer for liquid fuel. apparatus. 2. A fuel cell main body comprising a stack of cells having a hydrogen electrode and an oxygen electrode as a pair, having a cooler and being cooled by cooling water, and a fuel obtained by reforming the fuel. A reformer that produces a hydrogen-rich reformed gas that is supplied to the battery body,
Heat exchange so as to adjust the temperature condition of the fuel gas supplied to the reformer or the hydrogen-rich reformed gas supplied to the fuel electrode of the fuel cell main body or the temperature condition of the cell cooling water supplied to the fuel cell. It is a fuel cell power generator configured with a secondary cooling water system configured to flow secondary cooling water to the reactor system, and normally supplies gaseous fuel such as city gas to the reformer for reforming. Performs operation by producing hydrogen-rich reformed gas, supplying this hydrogen-rich reformed gas to the fuel cell body, and when the supply of gaseous fuel such as city gas is cut off, from the liquid fuel storage tank The supplied liquid fuel is heated by a vaporizer to be vaporized and supplied to the reformer to form a hydrogen-rich reformed gas, and the hydrogen-rich reformed gas is supplied to the fuel cell main body to operate. In a fuel cell power generator As a heating means for vaporizing the liquid fuel, a heat exchanger is provided in the vaporizer, and the secondary cooling water is battery cooling water, reformer combustion exhaust gas, or cathode exhaust gas. Liquid fuel by supplying at least a part of the secondary cooling water heated by heat exchange by simultaneously using two or three of the cell cooling water, the reformer combustion exhaust gas, and the air electrode. A fuel cell power generation device, comprising: heating the vaporizer. 3. The fuel cell power generator according to claim 1, wherein the vaporizer has a structure in which heating by heat exchange and heating by an electric heater are used in combination. 4. A means for controlling a flow rate of cooling water passing through the heat exchanger provided in the vaporizer, the flow rate of the cooling water being controlled to control the vaporized gas amount of the liquid fuel. The fuel cell power generator according to claim 1, 2 or 3. 5. The fuel cell power generator according to claim 1, wherein the supply amount of the liquid fuel to the vaporizer is controlled by an amount representative of the state inside the vaporizer. 6. The fuel cell power generator according to claim 5, wherein at least one of a liquid level, a gas temperature, and a gas pressure is used as an amount representative of the state inside the vaporizer.