JP3780714B2 - Fuel cell power generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell power generation apparatus that supplies fuel gas and air obtained by reforming raw fuel gas to a fuel cell body and obtains electric energy by an electrochemical reaction, and more particularly, pure water used for reforming raw fuel gas. It is related with the structure of the water treatment system for obtaining.
[0002]
[Prior art]
A fuel cell power generator is a reformer that reforms raw fuel gas such as city gas, LP gas, and methanol into a gas rich in hydrogen by steam reforming, and the reformed gas obtained by the reformer as fuel. As a main component, a fuel cell main body that generates electric power and an orthogonal transformation device that converts the direct current output of the fuel cell main body into alternating current, and the reformed gas generated by the reformer is a fuel cell power generation device The gas that is consumed inside the fuel cell main body according to the load and the utilization rate of hydrogen and that contains surplus hydrogen is led to the reformer as the exhaust gas of the fuel electrode and burned by the burner as reforming energy Is consumed.
[0003]
FIG. 3 is a flowchart showing the gas system and water system configurations of a conventional fuel cell power generator. In this figure, 1 is a fuel cell body, 2 is a desulfurizer, 3 is an ejector pump, 4 is a reformer, 5 is a CO converter, 6 is a steam separator, 7 is a condenser, 8 is an open air tank, Reference numeral 9 is a circulation pump, and 10 is an ion exchange type water treatment device.
In this configuration, raw fuel gas such as city gas and LP gas is sucked into the ejector pump 3, mixed with water vapor from the water vapor separator 6, and then supplied to the catalyst layer of the reformer 4. The hydrogen-rich gas generated by steam reforming in the reformer 4 is sent to the CO converter 5 to convert CO, which is a catalyst poisoning substance, into CO ₂ , and then as fuel gas in the fuel cell main body 1. It is sent to the fuel electrode 1b. On the other hand, reaction air is sent to the air electrode 1a of the fuel cell body 1 through a reaction air supply system 16 provided with a reaction air blower 16a. Moreover, a cooling plate 1c is incorporated in the fuel cell body 1, and pure water having a low electrical conductivity stored in the water vapor separator 6 and having a small amount of mineral foreign matters such as silica is contained in the cooling plate 1c. The fuel cell cooling water system 19 circulates and supplies heat to remove heat generated by the power generation of the fuel cell and maintain the temperature of the fuel cell body 1 at a predetermined operating temperature. Further, the off-gas discharged from the fuel electrode 1b contains unused hydrogen that does not contribute to the cell reaction, and is sent to the burner 4a of the reformer 4 by the off-gas supply system 18 and combustion air provided with an air blower 15a. It is mixed with the combustion air sent by the supply system 15, burned and effectively used for heating the reformer 4.
[0004]
Since a part of the pure water in the steam separator 6 is consumed as reforming steam, it is necessary to always replenish the pure water during the operation of the fuel cell power generator. For this reason, the combustion product water contained in the combustion exhaust gas discharged from the burner 4a of the reformer 4 and the reaction product water contained in the air off-gas discharged from the air electrode 1a are recovered and used. That is, as seen in the figure, the combustion exhaust gas and the air off gas are sent to the condenser 7, and the combustion product water and the reaction product water contained by being cooled by the cooling water are condensed and recovered into the open air tank 8. The The recovered water obtained is sent to a water treatment circulation loop 14 having a circulation pump 9, a front filter 11 with an air release button, an ion exchange type water treatment device 10 and a rear filter 12 with an air release button, and is supplied with pure water. A part of the water is sent to the water vapor separator 6 by a pure water makeup water system 20 equipped with a pure water makeup water pump 20a in order to replenish consumed pure water as reforming steam. Yes. The ion exchange type water treatment device 10 must always pass water at a speed within a certain range in order to prevent fluctuations in the adsorption speed of the ion exchange resin and drift in the resin tower. However, since the consumption amount of steam for reforming of the fuel cell power generator is usually smaller than the required water flow rate of the water treatment device 10, as shown in the figure, a circulation system is provided in the ion exchange type water treatment system. A part is sent to the steam separator 6. Further, when the electric conductivity of pure water obtained by the ion exchange type water treatment device 10 reaches a level of about 1 [μS / cm] or more, it is not suitable as cooling water to be supplied to the cooling plate 1c of the fuel cell body 1. Appropriate and requires replacement of the ion exchange resin. Therefore, in the illustrated ion exchange type water treatment apparatus 10, the resin tower is replaced with a resin tower filled with a new ion exchange resin every time the power generation time of the fuel cell power generation apparatus is 2000 to 3000 hours.
[0005]
[Problems to be solved by the invention]
As described above, in the conventional fuel cell power generation device, the combustion product water contained in the combustion exhaust gas and the reaction product water contained in the air off gas are recovered and purified by the ion exchange type water treatment device 10, and a part of the reaction product water is steamed. The power generation operation is continuously performed by supplementing the deionized water that is sent to the separator 6 and used as steam for reforming.
[0006]
By the way, the reformer 4 constituting the fuel cell power generator is a device that generates hydrogen by a chemical reaction at a high temperature, and the fuel cell main body 1 is a device that generates power at a high temperature. When starting and stopping, there is a risk that the reaction catalyst of the reformer 4 is physically destroyed by thermal stress, or phosphoric acid built in the fuel cell main body 1 is scattered. For this reason, the fuel cell power generator is generally operated continuously with few start-stops and is normally operated continuously for about 4000 to 8000 hours. On the other hand, in the ion exchange type water treatment apparatus 10 incorporated in the water treatment system, the ion exchange resin is exchanged every 2000 to 3000 hours as described above. Therefore, in the fuel cell power generation device, it is necessary to replace the ion exchange resin of the water treatment device 10 3 to 4 times a year or more frequently.
[0007]
The ion exchange resin exchange operation of the water treatment device 10 is performed by opening a bypass line valve provided in parallel to the water flow line to the water treatment device 10 and closing the valves disposed before and after the water treatment device 10 to pass the water. Is switched to a bypass line, and the resin tower is replaced with a resin tower filled with a new ion exchange resin. The resin tower is connected by a hard resin pipe, a resin hose, or the like. During replacement work, the water retained in the pipe and the hose drops and air flows into the pipe. Moreover, the new water treatment apparatus 10 contains gas. For this reason, the inflow air is discharged out of the system by the air release button attached to the water treatment device 10, the front filter 11 with the air release button, the rear filter 12 with the air release button, and the air release valve 13.
[0008]
However, even in the case where the front filter 11 with the air release button, the rear filter 12 with the air release button, and the air release valve 13 are incorporated in this way, the air accumulated in the pipe from the air release part to the pipe joining part It is impossible to discharge to the outside, and air bubbles staying inside the water treatment apparatus 10 or inside the pipe are separated after a while after the resin tower is replaced and flow into the water treatment circulation loop 14. Therefore, a small amount of air always enters the water treatment circulation loop 14 when the resin tower is replaced.
[0009]
When air flows into the water treatment circulation loop 14 in this way, air is mixed into the circulation water every time the water treatment device 10 is replaced, and passes through pure water supplied to the water vapor separator 6 to each part of the fuel cell power generation device. There is a risk that air enters and causes oxidation of the catalyst of the reformer 4, or the piping of the cooling system of the fuel cell body 1 is corroded or damaged. Further, if the amount of air flowing into the water treatment circulation loop 14 becomes too large and the amount of air flowing into the circulation pump 9 becomes excessive, the pump performance will be remarkably deteriorated. As a result, the amount of pure water supplied into the system will be insufficient. There is a possibility that the fuel cell power generator cannot be operated.
[0010]
Therefore, when the ion exchange resin is replaced by the water treatment apparatus 10, not only the resin tower replacement operation but also the air flowing into the water treatment circulation loop 14 is checked for the discharge pressure and discharge flow rate of the circulation pump 9. However, it is necessary to perform the operation of discharging to the outside with the air vent valve 13 or the like over a long period of time. For this reason, the replacement work of the ion exchange resin of the water treatment apparatus 10 requires a long and complicated work. There was a point.
[0011]
The object of the present invention is to solve the above-mentioned problems of the prior art, and to easily and shortly replace the ion exchange resin in an ion exchange type water treatment apparatus that purifies recovered water and obtains pure water for replenishment. An object of the present invention is to provide a fuel cell power generator that can be implemented in time, is easy to maintain, and has high reliability.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
Water comprising a water treatment device, a pipe and a pump for supplying water to be treated to the water treatment device, and a reflux pipe for returning treated water purified by the water treatment device to the pipe on the inlet side of the pump In a fuel cell power generator having a treatment system circulation loop and supplying a part of treated water flowing through the reflux pipe to the fuel cell cooling water system as makeup water,
(1) A buffer tank is provided in the reflux pipe path, and the treated water is refluxed via the buffer tank.
Or
(2) A switching pipe that branches from the return pipe and connects to a tank that stores the treated water, and switches between returning the treated water to the pump inlet side pipe and returning to the tank. Means shall be provided.
[0013]
In the fuel cell power generator configured as described in (1) above, even when air is mixed into the water treatment system when the ion exchange resin of the ion exchange type water treatment device is replaced, the mixed air is not stored in the buffer tank. Since the air stays in the upper part, the mixed air does not flow again through the water treatment system circulation loop and does not enter the circulation pump used for water flow.
[0014]
Further, in the fuel cell power generator configured as described in (2) above, the switching means is switched so that the treated water flowing through the reflux pipe returns to the tank storing the treated water, and the tank If the ion exchange resin of the ion exchange type water treatment device is replaced in that state, air is mixed into the water treatment system along with the replacement work. However, since the mixed air is discharged into the tank for storing the water to be treated, it does not flow again through the water treatment system circulation loop and does not enter the circulation pump used for water flow.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
<Example 1>
FIG. 1 is a flow diagram showing the configuration of a gas system and an aqueous system of a first embodiment of the fuel cell power generator of the present invention.
The difference between the configuration of the present embodiment and the configuration of the conventional example shown in FIG. 3 is the configuration of the water treatment system circulation loop 14A for purifying the recovered water collected in the open air tank 8, and the water treatment device. A characteristic of the present embodiment is that a buffer tank 30 for storing the mixed air is arranged in the pipe after flowing through 10.
[0016]
In the configuration of the present embodiment, even when air is mixed into the water treatment system circulation loop 14 </ b> A when the ion exchange resin of the water treatment device 10 is replaced, the mixed air stays in the upper part of the buffer tank 30. Therefore, it does not flow again into the water treatment system circulation loop 14 </ b> A, and there is no possibility of mixing into the circulation pump 9. Therefore, it is not necessary to spend a long time for the operation of extracting the air that has flowed in, unlike the conventional case, and the replacement work of the ion exchange resin of the water treatment apparatus 10 can be performed easily and in a short time.
[0017]
In addition, since the buffer tank 30 of this configuration is hermetically sealed, the flowing water does not come into contact with the outside air, so there is no risk of intrusion of dust or dissolution of oxygen or the like. The air vent valve 31 is used to extract the air stored in the buffer tank 30 to the outside when the air becomes excessive.
The buffer tank 30 used in this configuration determines the volume of the upper gas phase part from the amount of air that is expected to flow during ion exchange resin exchange work, and efficiently separates air from the treated water. Therefore, if the tank cross-sectional area is determined so that the flow velocity inside the buffer tank 30 is a low speed of about 0.3 [m / s] or less, effective separation of the air mixed from the water treatment circulating water can be achieved. Will be done.
[0018]
<Example 2>
FIG. 2 is a flowchart showing the gas system and water system configurations of the second embodiment of the fuel cell power generator of the present invention.
The feature of the present embodiment is that a switching valve 32 is incorporated in the pipe after passing through the ion exchange type water treatment device 10 of the water treatment system circulation loop 14B, and further, between the air release type tank 8 and the preceding stage. The connection pipe | tube provided with the valve | bulb 33 for switching is connected.
[0019]
In the configuration of this embodiment, when the ion exchange resin of the water treatment apparatus 10 is replaced, the switching valve 32 is switched from the open state to the closed state, and the switching valve 33 is switched from the closed state to the open state. After all the water that has passed through the water treatment apparatus 10 once flows into the open air tank 8 and then sent to the circulation pump 9, the ion exchange resin exchange operation is started. Therefore, even if air is mixed into the water treatment system circulation loop 14B due to the replacement work, the mixed air flows through the connecting pipe provided with the switching valve 33 and is sent to the open air tank 8 to open the air. The inside of the mold tank 8 is taken out into the air, and water that does not contain air is sent to the circulation pump 9. When the exchange operation of the ion exchange resin is completed, the switching valve 32 is changed from the closed state to the opened state, and the switching valve 33 is returned from the opened state to the closed state, so that the water treatment system circulation loop 14B becomes the original closed circuit. Driven.
[0020]
Also in this configuration, it is not necessary to take a long time for the operation of extracting the inflowed air as in the prior art, and the ion exchange resin replacement operation of the water treatment apparatus 10 can be performed easily and in a short time.
[0021]
【The invention's effect】
As described above, in the present invention, since the fuel cell power generator is configured as described in claim 1 or 2, the ion-exchange-type water treatment that purifies recovered water and obtains pure water for replenishment. The ion exchange resin exchange operation of the apparatus can be easily performed in a short time, and maintenance is easy, and a highly reliable fuel cell power generation apparatus can be obtained.
[Brief description of the drawings]
FIG. 1 is a flow diagram showing the configuration of a gas system and an aqueous system of a first embodiment of a fuel cell power generator of the present invention. FIG. 2 is a gas system and an aqueous system of a second embodiment of the fuel cell power generator of the present invention. Fig. 3 is a flow diagram showing the configuration of a gas system and a water system of a conventional fuel cell power generator.
DESCRIPTION OF SYMBOLS 1 Fuel cell main body 2 Desulfurizer 3 Ejector pump 4 Reformer 4a Burner 5 CO converter 6 Water vapor separator 7 Condenser 8 Open air tank 9 Circulation pump 10 Water treatment device (with air vent button)
11 Front filter with air release button 12 Rear filter with air release button 13 Air release valve 14, 14A, 14B Water treatment system circulation loop 19 Fuel cell cooling water system 20a Pure water replenishing water pump 30 Buffer tank 32 Switching valve 33 Switching valve

Claims (2)

Water comprising a water treatment device, a pipe and a pump for supplying water to be treated to the water treatment device, and a reflux pipe for returning treated water purified by the water treatment device to the pipe on the inlet side of the pump In a fuel cell power generator having a treatment system circulation loop and supplying a part of treated water flowing through the reflux pipe to the fuel cell cooling water system as makeup water,
A fuel cell power generator comprising a buffer tank in the reflux piping path, wherein the treated water is refluxed via the buffer tank. Water comprising a water treatment device, a pipe and a pump for supplying water to be treated to the water treatment device, and a reflux pipe for returning treated water purified by the water treatment device to the pipe on the inlet side of the pump In a fuel cell power generator having a treatment system circulation loop and supplying a part of treated water flowing through the reflux pipe to the fuel cell cooling water system as makeup water,
A switching pipe that branches from the reflux pipe and connects to a tank that stores the water to be treated; and includes a switching unit that switches between reflux of the treated water to the pump inlet side pipe and reflux to the tank. A fuel quantity battery power generator characterized by the above.

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