JP2008207990A - Co converting apparatus and method, and fuel cell system and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system which can well convert CO by controlling deactivation of a copper-based catalyst. <P>SOLUTION: When power generation treatment of a fuel cell system 100 is started, an inert gas is introduced into a CO converter 142 at 50°C or less. Therefore, since a CO conversion catalyst is not exposed to air when the temperature is raised to 50°C or higher at the time of starting the treatment for converting CO, CuO will not be newly formed, and aggregation of Cu in the CO conversion catalyst can be prevented when it is reduced at a temperature of 50°C or higher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

In the present invention, carbon monoxide (CO) remaining in a reformed gas mainly composed of hydrogen gas (H ₂ ) produced by reforming a raw material gas containing a hydrocarbon raw material is converted into a copper-based material. The present invention relates to a CO conversion device that converts carbon dioxide (CO ₂ ) with a CO conversion catalyst, a method thereof, a fuel cell system, and an operation control method thereof.

Conventionally, a fuel cell system that supplies hydrogen gas as a fuel gas to a fuel cell to generate electric power is known.
As these fuel cell systems, a configuration in which reformed gas or the like is purged when the system is started / stopped is known (see, for example, Patent Documents 1 to 6).

Patent Document 1 discloses that 350 to 400 in which the temperature of the reforming catalyst in the reformer is the oxidation temperature of the reforming catalyst after steam is circulated in the reformer system and the combustible gas is purged. A configuration is adopted in which air is introduced into the reformer and the water vapor in the reformer system is purged when the temperature falls to or below.
However, in the configuration in which air is purged as described in Patent Document 1, the reforming catalyst may be gradually deactivated by oxygen in the air even at a temperature of 350 ° C. or lower, and the reforming characteristics are reduced. Operation efficiency may be reduced.

Patent Document 2 describes a reformer in which a mixed reformed fuel obtained by mixing steam with a raw fuel such as a hydrocarbon gas such as methane or a liquid hydrocarbon such as methanol is heated by combustion of a burner. When stopping the operation of reforming by supplying to the reforming catalyst layer, the heating amount to the reforming catalyst layer by combustion of the reformer burner is changed to the hydrocarbon gas such as methane or the liquid hydrocarbon vapor such as methanol. The temperature of the reforming catalyst layer is lowered by reducing the amount of theoretical heat during the reforming reaction of the raw fuel. After the reforming catalyst layer falls below the pyrolysis temperature of the raw fuel, the supply of water vapor mixed with the raw fuel is stopped, and only the raw fuel is connected to the reformer and this reformer and generated by reforming. The reformed gas is supplied to a CO remover that removes CO in the reformed gas, and the moisture in the reformer and the CO remover is purged. At the time of start-up, the purged raw fuel is burned to raise the temperature of the reforming catalyst layer, and when the lowest temperature exceeds 100 ° C., the steam supply amount (S ) The ratio of S / C, which is the ratio of 3), is supplied to the mixed reformed fuel to continue the reforming reaction, and the generated reformed gas is burned by the burner to raise the temperature to the rated reforming operation. Has been adopted.
However, in the configuration of purging with the raw material as described in Patent Document 2, the system configuration becomes complicated and the control may be difficult.

The one described in Patent Document 3 sequentially connects a reforming section, a CO conversion section, a CO removal section, and a fuel cell, and has a bypass having a pump and a heat exchanger at the outlet of the CO removal section and the reformer. Connect the tubes. When the operation is stopped, a configuration is adopted in which the reformed gas flowing out from the CO removing unit is circulated by flowing into the reforming unit via a bypass pipe by driving a pump.
However, in the configuration of purging with the reformed gas as described in Patent Document 3, the purged reformed gas is discharged as it is at the time of restart. For example, in the case of a system that is stopped every day, the purge is performed. The amount of the reformed gas that is used and discharged becomes large, and more efficient is desired from the viewpoint of energy efficiency. In addition, the catalyst may be oxidized and coked, leading to a decrease in activity.

Patent Document 4 describes that at the start of operation, the hydrogen rich gas from which carbon monoxide has not been sufficiently removed is removed until the temperature of the carbon monoxide remover connected to the reformer becomes sufficiently high. The temperature is increased by burning with a burner. Then, after the carbon monoxide removing device is heated to a temperature at which stable treatment can be performed, hydrogen rich gas is supplied to the fuel cell to generate power. When the operation is stopped, the raw material gas is supplied together with the water vapor to a temperature at which the raw material is not carbonized, and the hydrogen rich gas is not generated, or the amount of the hydrogen rich gas having a concentration that does not react even when exposed to the air is below a predetermined temperature. Reduce the reformer temperature. Then, the remaining hydrogen-rich gas is burned with a burner so as to extrude with the source gas, and after a predetermined time has elapsed, the source gas is stopped, air is supplied and the remaining source gas is burned with the burner and replaced with air. The structure to do is taken.
However, in the configuration described in Patent Document 4, since the hydrogen rich gas and the raw material gas are combusted at the time of starting and stopping, more efficiency is desired from the viewpoint of energy efficiency. Further, since the purge is performed with air, the catalyst may be deactivated by oxygen in the air even at about 300 ° C. or lower, and there is a possibility that the processing efficiency is lowered and the operation efficiency is lowered. Furthermore, there is a possibility that the activity is reduced due to coking of the catalyst.

In Patent Document 5, a part of the reformed gas is guided to the hydrogen storage alloy through the reformed gas line during the operation of the reformer to absorb only hydrogen, and the hydrogen storage is performed when the reformer is stopped. A configuration is adopted in which hydrogen is released from the alloy, hydrogen is supplied to the upstream side of the reformer through the hydrogen gas line, residual fuel and moisture in the reformer are purged, and hydrogen is sealed in the reformer. It has been.
However, in the configuration of purging with hydrogen gas as described in Patent Document 5, a special configuration using an expensive hydrogen storage alloy and complicated control such as pressure control for storing and releasing hydrogen during operation and stoppage are required. In the case where control is required, especially when the system is used at home, a small and inexpensive system configuration is required to expand the use.

In Patent Document 6, when the system is stopped, the valve of the outlet conduit of one of the CO conversion unit and the CO removal unit sequentially connected to the steam reformer including the combustion unit and the reforming unit is closed, and the reforming is performed. The supply of raw material gas and water to the department is stopped. Then, when the reforming section and the CO conversion section are below a predetermined temperature at which the hydrocarbon decomposition reaction does not proceed and carbon is not deposited due to the decomposition reaction, the valve is opened and the raw material gas is supplied into the system. To purge the reformed gas. Thereafter, the valve is closed and the system is filled with the raw material gas.
However, in the configuration of purging with the reformed gas as described in Patent Document 6, similarly to Patent Document 3, the reformed gas purged at the time of restart is discharged as it is, and is stopped, for example, every day. In the case of the system, the amount of the reformed gas that is used for purge and discharged becomes large, and more efficiency is desired from the viewpoint of energy efficiency.

JP 2002-8701 A JP 2005-209642 A JP 2005-216500 A JP 2005-332834 A JP 2000-21431 A JP 2004-307236 A

By the way, after the reforming process by the reformer, CO that affects the fuel cell is converted to CO ₂ by a catalyst and removed. In this modification, the use of a copper (Cu) -based catalyst is known.
However, this copper-based catalyst repeats oxidation-reduction at the time of starting and stopping in the conventional methods as described in Patent Document 1 to Patent Document 6 described above, so that copper agglomeration proceeds and CO conversion treatment is performed. Activity may be reduced.

  In view of these points, an object of the present invention is to provide a CO conversion device, a method thereof, a fuel cell system, and an operation control thereof, in which the deactivation of a copper-based catalyst is suppressed and a good carbon monoxide conversion treatment is obtained. Provide a method.

In order to solve the above problems, the present inventors have made extensive studies and found the following to complete the present invention.
Specifically, when a copper-based CO conversion catalyst is exposed to a hydrogen-steam atmosphere in which hydrogen is supplied to a steam atmosphere at 250 ° C. and then exposed to the steam atmosphere without changing the temperature, the monovalent copper oxide is oxidized. As (Cu ₂ O) increases, copper (Cu) decreases. Further, when returning to the hydrogen water vapor atmosphere without changing the temperature and reducing, Cu increases, Cu ₂ O decreases, and the ratio of Cu and Cu ₂ O returns to the state before oxidation. And it discovered that Cu produced | generated by this reduction | restoration was not aggregated similarly to before oxidation.
Further, the ratio of Cu ₂ O and Cu does not change even when the CO conversion catalyst in the inert gas atmosphere at 50 ° C. is exposed to the air atmosphere, but when it is heated to 250 ° C., it is oxidized, As Cu ₂ O increases, Cu decreases, and bivalent copper oxide (CuO) is newly generated at a higher abundance ratio than Cu ₂ O. Furthermore, even if it is exposed to an inert gas atmosphere without changing the temperature, the ratio of Cu ₂ O, Cu, and CuO does not change, but after that, when exposed to a hydrogen atmosphere without changing the temperature, the Cu is reduced. As it increases, Cu ₂ O and CuO decrease, CuO disappears, and the ratio of Cu and Cu ₂ O returns to the pre-oxidation state, but the Cu produced by this reduction aggregates compared to before oxidation. I found out.
In other words, even if redox was repeated at 250 ° C., Cu did not aggregate, and after CuO was formed by oxidation in an air atmosphere at 50 ° C. or higher, Cu was aggregated when reduced at 250 ° C. It was.
The present invention has been completed based on such findings.

That is, in the CO conversion device according to the present invention, a reformed gas mainly containing hydrogen gas (H ₂ ) generated by reforming a raw material gas containing a hydrocarbon raw material is introduced, and the reforming is performed. A CO conversion device filled with a copper-based CO conversion catalyst for converting carbon monoxide (CO) remaining in a gas into carbon dioxide (CO ₂ ), wherein the CO conversion catalyst is capable of flowing the reformed gas. And at least one of a reducing gas and an inert gas at 50 ° C. or lower when starting the process of introducing the reformed gas into the shift container and converting the CO into the shift container And a control device for introducing gas into the shift vessel.
In the present invention, a copper-based CO conversion catalyst for converting CO remaining in a reformed gas mainly composed of H ₂ produced by reforming a raw material gas containing a hydrocarbon raw material into CO ₂ is filled. When starting the process of transforming CO in the transformed container, the controller introduces at least one of the reducing gas and the inert gas into the transformation container at 50 ° C. or lower.
As a result, at the start of the CO modification treatment, the CO conversion catalyst is not exposed to the air atmosphere when the temperature is 50 ° C. or higher, so that no new CuO is generated, and 50 ° C. or higher. The Cu of the CO shift catalyst does not agglomerate when it is reduced at the above temperature. Therefore, the deactivation of the CO shift catalyst due to copper aggregation is suppressed, and a good carbon monoxide shift treatment can be stably obtained for a long period of time.

And in this invention, it is CO conversion apparatus of Claim 1, Comprising: The said control apparatus introduces the said at least any one gas into the said conversion container, before starting the process which converts the said CO. A configuration is preferred.
In the present invention, the control device introduces at least one of the aforementioned gases into the shift container before the start of the CO shift process.
As a result, for example, after recognizing the start of the transformation process, the gas is introduced without performing control to detect the temperature of the transformation container, so that a good carbon monoxide transformation process is stable for a long time with simpler control. Is obtained.

Further, in the present invention, the CO conversion device according to claim 1 or 2, wherein the control device supplies a purge gas when stopping the process of introducing the reformed gas and converting the CO. A configuration in which the shift container is introduced and filled is preferable.
According to the present invention, when the control device stops the process of introducing the reformed gas and converting CO, the purge gas is introduced into the shift vessel and filled.
As a result, the reformed gas or the water vapor derived from the raw material gas is purged by the purge gas, and the CO shift catalyst is oxidized and the reformed gas is introduced and rapidly reduced when starting the CO shift process. It is possible to prevent the copper from agglomerating and to efficiently obtain a good activity stably for a long period of time.

Furthermore, in this invention, it is a CO conversion apparatus in any one of Claim 1 thru | or 3, Comprising: The said control apparatus has the structure filled with the said reformed gas as said reducing gas.
According to this invention, the reformed gas is filled as the reducing gas.
As a result, the reformed gas obtained by the reforming process is used, so there is no need to separately use a purging gas from the outside of the processing system, and efficient CO conversion treatment can be stopped and started. It is done.

And in this invention, it is a CO conversion apparatus in any one of Claim 1 thru | or 4, Comprising: The said control apparatus has the structure filled with dry gas as said at least any one gas.
In the present invention, the control device supplies a dry gas, that is, a gas not containing moisture such as water vapor, as the purge gas.
As a result, for example, when water is agglomerated at the time of stopping the CO conversion treatment and the copper of the CO conversion catalyst oxidized at the start of the conversion treatment is rapidly reduced, the copper can be prevented from agglomerating. Activity can be obtained stably over a long period of time.

In the CO conversion method of the present invention, carbon monoxide (CO) remaining in a reformed gas mainly composed of hydrogen gas (H ₂ ) generated by reforming a raw material gas containing a hydrocarbon raw material is converted. , A CO conversion method for converting to carbon dioxide (CO ₂ ) with a copper-based CO conversion catalyst,
At the start of the process of converting CO in the reformed gas, at least one of a reducing gas and an inert gas is allowed to flow through the CO conversion catalyst at 50 ° C. or lower.
In the present invention, to denature CO remaining the H ₂ produced a raw material gas containing hydrocarbon feedstock in reforming processes in the reformed gas mainly composed, in CO ₂ in the CO shifting catalyst of the copper-based When starting the treatment, at least one of a reducing gas and an inert gas is allowed to flow through the CO conversion catalyst at 50 ° C. or lower.
Thus, as described above, the deactivation of the CO shift catalyst due to the aggregation of copper is suppressed, and a good carbon monoxide shift treatment can be stably obtained for a long period of time.

The fuel cell system according to the present invention includes a reforming means for reforming a raw material gas containing a hydrocarbon raw material into a reformed gas containing hydrogen gas (H ₂ ) as a main component, and connected to the reforming means. 6. The CO conversion apparatus according to claim 1, which converts carbon monoxide (CO) remaining in the reformed gas into carbon dioxide (CO ₂ ), and an oxygen-containing gas for supplying an oxygen-containing gas. Electricity is generated using a supply means, a reformed gas generated by the reforming means and subjected to a process for converting CO by the CO converter, and the oxygen-containing gas supplied by the oxygen-containing gas supply means A fuel cell; and an introduction gas supply unit configured to introduce at least one of a reducing gas and an inert gas into the reforming unit and the CO conversion device by the control device of the CO conversion device. Characterized in that was.
The fuel cell system according to the present invention includes a reforming means for reforming a raw material gas containing a hydrocarbon raw material into a reformed gas containing hydrogen gas (H ₂ ) as a main component, and is connected to the reforming means. A CO conversion catalyst that converts carbon monoxide (CO) remaining in the reformed gas into carbon dioxide (CO ₂ ) is supplied with a shift container filled with the reformed gas so that it can flow, and an oxygen-containing gas is supplied. An oxygen-containing gas supply means, an introduction gas supply means for introducing at least one of a reducing gas and an inert gas into the reforming means and the CO conversion device, and the reformed gas in the shift vessel And a control device for introducing at least one of the gases into the transformation container by the introduction gas supply means at 50 ° C. or lower when starting the treatment to introduce and transform the CO. You .
In these inventions, the control device reduces the reduction gas at 50 ° C. or lower into a shift vessel filled with a CO shift catalyst that converts CO remaining in the reformed gas mainly composed of hydrogen gas (H ₂ ) into CO _2. At least one of a gas and an inert gas is introduced.
As a result, the deactivation of the CO shift catalyst due to copper aggregation is suppressed as described above, and a good carbon monoxide shift treatment can be stably obtained over a long period of time, in conjunction with the stop / start of the reforming treatment. Therefore, efficient and easy operation control can be obtained.

Further, in the present invention, the fuel cell system according to claim 7 or 8, further comprising a raw material gas supply means for supplying the raw material gas generated by mixing the hydrocarbon raw material with water vapor to the reforming means. And the introduction gas supply means includes at least any gas obtained by gas-liquid separation of an effluent flowing out from at least one of the reforming means, the CO conversion device, and the fuel cell. A configuration including a circulation means for supplying the gas as one of the gases is preferable.
In this invention, the reforming means for generating the reformed gas by supplying the raw material gas generated by mixing the water vapor to the hydrocarbon raw material from the raw material gas supplying means by the circulation means of the introduction gas supply means, Outflow that flows out from at least one of a CO conversion device that converts CO in the generated reformed gas, and a fuel cell that generates power using the reformed gas in which CO is converted by the CO conversion device The gas obtained by gas-liquid separation is supplied to the reforming means and the CO denaturing apparatus as at least one of the above-mentioned gases.
As a result, there is no need to supply at least one of the above-mentioned gases at the start / stop of the operation, and the gas is reused and the supplied gas is returned in a simple configuration. It is possible to prevent the reduction of the activity due to the oxidation of the catalyst due to the dew condensation of the water vapor mixed and returned to the effluent derived from the raw material gas and to reduce the activity, and the long-term stable power generation is obtained.

In the operation control method for a fuel cell system of the present invention, a raw material gas containing a hydrocarbon raw material is reformed by a reforming means into a reformed gas containing hydrogen gas (H ₂ ) as a main component. The remaining carbon monoxide (CO) is converted to carbon dioxide (CO ₂ ) by a copper-based CO conversion catalyst packed in a CO conversion device, and then supplied to the fuel cell to control the operating state of the fuel cell system that generates power. An operation control method for a fuel cell system, wherein when the raw material gas is supplied and power is generated by the fuel cell, at least one of a reducing gas and an inert gas is converted to the CO at 50 ° C. or lower. It is made to distribute | circulate to a shift catalyst.
In this invention, a raw material gas containing a hydrocarbon raw material is reformed by a reforming means into a reformed gas containing H ₂ as a main component, and CO remaining in the reformed gas is converted into CO by a copper-based CO shift catalyst. _{In the} fuel cell system that is transformed into ₂ and then supplied to the fuel cell to generate power, when starting the power generation after supplying the raw material gas and generating power in the fuel cell, the reducing gas and inert gas At least one of the gases is passed through the CO shift catalyst.
As a result, the deactivation of the CO conversion catalyst due to copper aggregation is suppressed, a good carbon monoxide conversion treatment can be stably obtained for a long period of time, and it can be controlled in conjunction with the stop / start of the reforming treatment. Easily possible and linked control provides more efficient and easier operation control.

Further, in the present invention, the fuel cell system operation control method according to claim 10, wherein the raw material gas is generated by mixing water vapor with the hydrocarbon raw material. When power generation is stopped, the supply of the hydrocarbon raw material is stopped and the steam is supplied to the reforming means and the CO conversion device to be cooled, and the supply of the steam is performed after the cooling process. It is preferable to perform a purge step of stopping and supplying the purge gas to the reforming means and the CO converter and filling the purge gas.
In this invention, when power generation in the fuel cell is stopped, the supply of the hydrocarbon raw material is stopped, and the steam that generates the raw material gas by mixing with the hydrocarbon raw material is supplied to the reforming means and the CO conversion device for cooling. A cooling step is performed. Cooling to some extent in the cooling process, for example, after the CO conversion catalyst is cooled to a temperature at which the inconvenience such as condensation of water vapor does not occur or the temperature at which the CO conversion catalyst oxidizes decreases to 250 ° C. or lower, the supply of water vapor is stopped. Then, a purge process is performed in which the purge gas is supplied to the reforming means and the CO conversion device and filled.
This allows rapid cooling of the CO conversion catalyst of the reforming means and the CO conversion device by supplying the steam, and the purge gas is restarted after a predetermined time elapses, for example, before the steam is precipitated as water by cooling to some extent. It is possible to prevent problems such as supply and precipitation as water due to residual water vapor, resulting in a decrease in the activity of the catalyst, and quick and efficient shutdown. Furthermore, since water due to water vapor or condensation does not remain at the time of restarting, it is possible to prevent inconveniences such as agglomeration of copper of the CO shift catalyst and a decrease in activity at the time of temperature rise, and a long-term stable treatment can be obtained. . In addition, the hydrocarbon raw material can be prevented from remaining, and the hydrocarbon raw material remaining due to residual heat can be carbonized to prevent inconveniences such as a decrease in catalyst activity and blockage.

Hereinafter, an embodiment according to the fuel cell system of the present invention will be described.
In this embodiment, the configuration of a fuel cell system that uses kerosene as a hydrocarbon raw material is exemplified. However, the fuel cell system is not limited to kerosene, for example, various liquid fuels such as light oil and naphtha, for example, city gas or LPG Petroleum Gas) can be used in various fuel cell systems that also target gaseous fuel such as propane gas. Furthermore, the present invention can be applied to a manufacturing apparatus that manufactures fuel gas supplied to a fuel cell.
FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system in the present embodiment.

[Configuration of fuel cell system]
In FIG. 1, reference numeral 100 denotes a fuel cell system. The fuel cell system 100 is a system that uses liquid fuel as a raw material to be reformed into a fuel gas containing hydrogen as a main component and causes the fuel cell 170 to generate electric power.
This fuel cell system 100 also functions as a liquid fuel supply means 110, a desulfurization means 120, a vaporization means 130, a reforming unit 140, an oxygen-containing gas supply means 150, a fuel cell 170, and an introduction gas supply means. A purge gas supply means 180 that circulates, a circulation means 190 that constitutes the introduction gas supply means, and the like. And the liquid fuel supply means 110, the desulfurization means 120, and the vaporization means 130 which comprise the upstream of the reforming unit 140 comprise the raw material gas supply means of this invention.

The liquid fuel supply unit 110 includes a liquid fuel storage tank 111 and a liquid fuel supply path 112.
The liquid fuel storage tank 111 stores liquid fuel 111A such as kerosene so that it can flow out. Here, the liquid fuel 111A is not limited to kerosene, and various liquid fuels such as light oil and naphtha can be used.
The liquid fuel supply path 112 is connected to the liquid fuel storage tank 111, and distributes the liquid fuel 111A stored in the liquid fuel storage tank 111. The liquid fuel supply path 112 includes a liquid fuel pump 112A and a fuel supply valve 112B, and includes a fuel supply pipe 112C having one end connected to the liquid fuel storage tank 111 and the other end connected to the desulfurization means 120. The liquid fuel supply path 112 distributes the liquid fuel 111A stored in the liquid fuel storage tank 111 to the desulfurization means 120 by driving the liquid fuel pump 112A.
The liquid fuel supply means 110 is not limited to the configuration provided with the liquid fuel storage tank 111. For example, the liquid fuel supply means 110 is connected to the separately provided liquid fuel storage tank 111 and stores liquid in the liquid fuel storage tank 111. It is good also as a structure provided only with the liquid fuel supply path 112 which distribute | circulates the fuel 111A.

The desulfurization means 120 includes a desulfurizer 121, a buffer tank (not shown), and the like.
The desulfurizer 121 is a sulfur containing liquid fuel 111A supplied from the liquid fuel storage tank 111 via the liquid fuel supply path 112 at, for example, about 300 [ml / hour] in the liquid fuel 111A by the liquid phase adsorption method. A desulfurization treatment is carried out to adsorb and remove the compound. The desulfurizer 121 includes a desulfurization agent container, a desulfurization heating unit, and the like, which are not illustrated. The desulfurization agent container is formed in a substantially cylindrical shape filled with a desulfurization agent, and the other end of the fuel supply pipe 112C of the liquid fuel supply path 112 is connected to one end in the axial direction so that the liquid fuel 111A flows in (not shown). It has an inflow port, and has an unillustrated outflow port for flowing out the liquid fuel 111A connected to the buffer tank and in contact with the desulfurization agent at the other end in the axial direction. The desulfurizer 121 is in a state where the axial direction of the desulfurizing agent container is substantially along the vertical direction, and the inflow port is opened downward in the vertical direction and the outflow port is opened upward in the vertical direction. Installed. That is, the desulfurizer 121 is installed in a state in which the liquid fuel 111A flows in from the lower part of the desulfurizing agent container and flows out from the upper part while flowing upward in the vertical direction. The desulfurization heating means includes, for example, an electric heater such as a sheathed heater spirally disposed on the outer surface of the desulfurizing agent container, and desulfurizes by heating the liquid fuel 111A flowing from the outer surface side of the desulfurizing agent container to about 200 ° C., for example. Promote processing. In addition, the outer surface of the desulfurizer 121 is provided with a heat insulating material that covers and heat-insulates the outer surface of the desulfurizing agent container together with the electric heater. Further, the electric heater is not limited to the spiral arrangement, and may be arranged so as to be folded back along the longitudinal direction of the desulfurization agent container, for example.
The buffer tank is a tank that temporarily stores the liquid fuel 111A desulfurized by the desulfurizer 121. The buffer tank is provided with a liquid amount sensor that detects the amount of liquid fuel 111A to be stored. This liquid amount sensor outputs a signal related to the liquid amount for controlling the driving of the liquid fuel pump 112A in the liquid fuel supply path 112 in a state where a predetermined amount is stored in the buffer tank. A desulfurization fuel path 122 having a desulfurization fuel valve 122A and a desulfurization fuel pump (not shown) is connected to the lower portion of the buffer tank, and the stored desulfurized liquid fuel 111A can be supplied to the vaporizing means 130. Yes. In addition, a combustion gas supply path (not shown) is connected to the upper part of the buffer tank so that the vaporized liquid fuel 111A is discharged, for example, supplied as combustion gas burned by the reforming unit 140.

The vaporization means 130 is connected to the desulfurization fuel path 122 of the desulfurization means 120, and vaporizes the liquid fuel 111A after the desulfurization process supplied from the desulfurization means 120. The vaporization means 130 includes a vaporizer 131, a heat exchange device 132, a water supply path 133, and the like. The vaporization means 130 may be configured integrally with the reforming unit 140 or may be a separate configuration.
The vaporizer 131 is connected to the desulfurization fuel path 122 and supplied with the liquid fuel 111A, and is connected to the heat exchange device 132 and supplied with water vapor from the heat exchange device 132. The vaporizer 131 appropriately mixes the liquid fuel 111A and water vapor to vaporize, that is, generate vaporized liquid fuel that is a raw material gas. The vaporizer 131 is connected to the reforming unit 140 and supplies the reformed unit 140 with the vaporized liquid fuel that is the liquid fuel 111 </ b> A vaporized by mixing the water vapor.
The heat exchanging device 132 is connected to the reforming unit 140, cools the exhaust gas exhausted from the reforming unit 140, generates steam from water that exchanges heat with the exhaust gas, and supplies the generated steam to the vaporizer 131. Specifically, a pure water tank 133B for storing pure water 133A is connected to the heat exchanging device 132 via a water supply path 133 having a transfer pump 133C and a transfer valve 133D, and from the pure water tank 133B to the pure water 133A. Is supplied. The pure water 133A is heat-exchanged with the exhaust gas from the reforming unit 140 and supplied to the vaporizer 131 as water vapor. The pure water tank 133B may be configured to store pure water 133A that does not contain impurities such as distilled water and to supply, for example, tap water or the like after being purified.

The reforming unit 140 reforms the vaporized liquid fuel vaporized by mixing the water vapor by the vaporization means 130 into a hydrogen-rich fuel gas. The reforming unit 140 includes a reformer 141 as reforming means, a CO converter 142 as a CO converter, a CO selective oxidizer 143, and the like.
The reformer 141 includes a reforming catalyst such as a nickel catalyst (not shown) and a burner 141A as a heating device. The burner 141 </ b> A is connected to a fuel transfer path 144 that is connected to the liquid fuel storage tank 111 and has a transfer pump 144 </ b> A to transfer the liquid fuel 111 </ b> A stored in the liquid fuel storage tank 111. In addition, an air supply path 145 having an air supply blower 145A and an air supply valve 145B is connected to the burner 141A, and combustion air is supplied by driving the air supply blower 145A. Further, the burner 141A is connected to a fuel cell 170, which will be described in detail later, and has an open / close valve 146A, which is connected to a fuel gas supply path 146 as a return means for discharging fuel gas which is an effluent discharged from the fuel cell 170. Has been. The burner 141A burns the fuel gas supplied via the fuel conveyance path 144 and the fuel gas supplied via the fuel gas supply path 146 with the air supplied from the air supply blower 145A, and reformed. The vaporized liquid fuel supplied to the vessel 141 is steam reformed into a hydrogen-rich fuel gas. The high-temperature exhaust gas generated by the combustion of the burner 141A is supplied to the heat exchange device 132 of the vaporizing means 130, cooled by heat exchange with the pure water 133A, and exhausted into the outside air.
The CO converter 142 converts carbon monoxide (CO) contained in the hydrogen-rich fuel gas flowing out from the reformer 141 into carbon dioxide (CO ₂ ). The CO converter 142 includes a CO conversion container having an internal space filled with a copper-based CO conversion catalyst (not shown) such as a Cu-ZnO-Al ₂ O ₃ catalyst to form a CO conversion layer.
The CO selective oxidizer 143 is connected to the oxidation blower 143A and supplied with air. Then, the CO selective oxidizer 143 oxidizes the remaining CO that is not transformed by the CO transformer 142 to CO ₂ by oxygen in the supplied air, and removes CO in the fuel gas.
Note that the CO converter 142 and the CO selective oxidizer 143 may be integrated with the reformer 141. In addition to the CO selective oxidizer 143, a device for adsorbing and removing CO may be provided.

The oxygen-containing gas supply means 150 supplies, for example, air to the fuel cell 170 as the oxygen-containing gas.
Specifically, the oxygen-containing gas supply means 150 includes a blower 151, an air supply pipe 152 having one end connected to the blower 151 and the other end connected to the fuel cell 170, and air provided in the air supply pipe 152. And a valve 153. Then, air is supplied to the fuel cell 170 via the air supply pipe 152 by driving the blower 151.

Further, a fuel cell 170 is connected to the CO selective oxidizer 143 of the reforming unit 140 via a fuel gas supply path 163 having a fuel gas valve 163A, and the hydrogen-rich fuel gas reformed by the reforming unit 140. For example, the fuel gas humidified with pure water 133A supplied from, for example, the pure water tank 133B is supplied to the fuel cell 170 while being adjusted to about 60 to 70 ° C. with a humidifier or the like.
The fuel gas supply path 163 is connected to the bypass path 165 at a position upstream of the fuel gas valve 163A. The bypass path 165 has a switching valve 165A and is connected to the downstream side of the opening / closing valve 146A in the fuel gas supply path 146. The bypass path 165 supplies the fuel gas flowing through the fuel gas supply path 163 to the burner 141A of the reformer 141 via the fuel gas supply path 146.

The fuel cell 170 reacts hydrogen and oxygen to generate DC power. The fuel cell 170 is, for example, a solid polymer fuel cell, and includes a positive electrode 171, a negative electrode 172, and a polymer electrolyte membrane (not shown) disposed between the positive electrode 171 and the negative electrode 172. The positive electrode 171 side is supplied with air humidified to about 60 to 70 ° C. by a humidifier, for example, from the oxygen-containing gas supply means 150, and the negative electrode 172 side is, for example, hydrogen-rich fuel gas humidified by a humidifier Is supplied. Then, hydrogen (fuel gas) and oxygen in the air react to generate water (pure water 133A), and DC power is generated between the positive electrode 171 and the negative electrode 172.
The negative electrode 172 side is connected to the burner 141A of the reformer 141 via the fuel gas supply path 146 as described above, and supplies the surplus hydrogen as fuel for the burner 141A. A separator 175 is connected to the positive electrode 171 side. The separator 175 is supplied with air used for the reaction from the positive electrode 171 side, and is separated into air for the gas phase and water (pure water 133A) for the liquid phase. The separated air is exhausted to the outside air. And the pure water tank 133B is connected to the separator 175, and the separated water (pure water 133A) is supplied to the pure water tank 133B.
The fuel cell 170 is provided with a cooling device 177. The cooling device 177 is provided with a heat recovery device 177 A attached to the fuel cell 170. A pure water tank 133B is connected to the heat recovery device 177A via a cooling water circulation path 178 including a cooling water circulation pump 178A and a heat exchanger 178B. The cooling device 177 drives the cooling water circulation pump 178A to circulate pure water 133A serving as cooling water between the heat recovery device 177A and the pure water tank 133B through the cooling water circulation path 178, and generates heat with power generation. The fuel cell 170 is cooled and heat is recovered. The heat exchanger 178B exchanges heat with the pure water 133A circulated and heat recovered by the heat recovery device 177A, for example, tap water. The tap water warmed by this heat exchange is directly supplied to other facilities such as a bath for effective use. In addition to heat exchange with tap water, it may be used effectively for other facilities such as generating electricity from heat obtained by heat exchange.

The purge gas supply means 180 sequentially supplies an inert gas and purge air when the operation of the fuel cell system 100 is stopped, and sequentially replaces and fills the inside of the fuel cell system 100 with the inert gas and purge air, that is, purge. Let The purge gas supply means 180 includes an inert gas tank 181, a purge gas supply path 182, and a purge blower 183.
The inert gas tank 181 stores, for example, nitrogen gas (N ₂ ), which is a dry gas, as an inert gas so that it can flow out. Here, the inert gas is not limited to nitrogen gas, and various inert gases such as helium gas and argon gas can be used. The inert gas, which will be described in detail later, is preferably a dry gas because there is a possibility that the catalyst activity may be reduced due to oxidation of the catalyst due to dew condensation when the operation is stopped, particularly oxidation during temperature rise.
The purge gas supply path 182 is connected to the inert gas tank 181 and the purge blower 183, and the inert gas stored in the inert gas tank 181 and the purge air supplied by driving the purge blower 183 circulate therethrough. Supply downstream and purge. Specifically, the purge gas supply path 182 has a three-way valve 182A, an upstream side is connected to an inert gas tank 181 and an upstream side is connected to a purge air blower pipe 183. And. Further, the downstream side of the three-way valve 182A is branched into a first supply pipe 182C and a second supply pipe 182D. The first supply pipe 182C has a first valve 182C1, and its downstream end is downstream of the desulfurization means 120 and upstream of the vaporizer 131 of the vaporization means 130, that is, downstream of the desulfurization fuel valve 122A in the desulfurization fuel path 122. Connected to the side. The second supply pipe 182D has a second valve 182D1, and the downstream end is connected to the downstream side of the fuel gas valve 163A in the fuel gas supply path 163. Further, a third supply pipe 182E is connected to the first supply pipe 182C so as to be located downstream of the first valve 182C1. The third supply pipe 182E has a third valve 182E1, and stops the drive of the fuel transport path 144 downstream of the transport pump 144A and upstream of the burner 141A, particularly the transport pump 144A, and supplies the liquid fuel 111A. It is connected to the upstream side from the position where the liquid fuel 111A remains in the fuel conveyance path 144 when it stops and the heat of the reformer 141 vaporizes.

The circulation means 190 is connected to the fuel cell 170 and supplies the effluent flowing out from the fuel cell 170, that is, the effluent such as fuel gas and inert gas discharged from the fuel cell 170 to the downstream side from the desulfurization means 120. The circulation unit 190 includes a circulation path 191, a storage unit 192, and a circulation blower 193.
The circulation path 191 has a circulation valve 191 </ b> A, one end connected to the negative electrode 172 side of the fuel cell 170, that is, connected upstream from the open / close valve 146 </ b> A in the fuel gas supply path 146, and the other end downstream from the desulfurization means 120. Connected, that is, connected to the upstream side of the first valve 182C1 in the first supply pipe 182C of the purge gas supply path 182 and the effluent discharged from the negative electrode 172 of the fuel cell 170 is upstream of the vaporizer 131 on the downstream side of the desulfurization means 120. To supply.
The storage unit 192 is provided in the circulation path 191 and stores the effluent that flows out from the negative electrode 172 of the fuel cell 170. The storage means 192 is provided with a gas-liquid separation means 192A. The gas-liquid separation unit 192A gas-liquid separates the effluent flowing from the negative electrode 172 through the circulation path 191 and flowing into the storage unit 192. Specifically, the gas-liquid separation unit 192A is provided in a storage tank (not shown) constituting the storage unit 192, and only water (pure water 133A) that is a liquid phase component in the effluent flows to the pure water tank 133B. A drain trap (not shown) is provided, and a vent trap that circulates only the gas phase in the effluent to the downstream side of the circulation path 191 is provided.
The circulation blower 193 is provided on the downstream side of the storage unit 192 in the circulation path 191, and supplies the gas phase component stored in the storage unit 192 to the downstream side of the desulfurization unit 120 by driving.

The fuel cell system 100 includes a control device (not shown) that controls the operation of the entire system.
This control device controls the flow rate of the liquid fuel 111A, controls the power supplied to the electric heater which is the heating condition of the desulfurization heating means of the desulfurizer 121, controls the combustion of the burner 141A of the reformer 141, and heats the steam in the heat exchanger 132. Control of supply amount of pure water 133A for generation, temperature management, power generation amount management, inert gas, purge processing of purge air, and the like are performed.
As an inert gas purge process, a power generation process is carried out when air or the like is present in maintenance such as air purge or catalyst replacement or pipe inspection, which will be described later, that is, a reformer 141 performs a reforming process. When the CO in the reformed gas generated is converted to CO ₂ by the CO converter 142, an inert gas is introduced into the CO converter 142 at 50 ° C. or lower. Here, when an inert gas is introduced at a temperature higher than 50 ° C. in the presence of air inside, when the CO shift catalyst oxidized with air at a temperature higher than 50 ° C. is reduced, copper aggregates. Activity may be reduced. As a result, an inert gas is introduced at 50 ° C. or lower, air is not present at a temperature higher than 50 ° C., and then the CO shift catalyst is reduced.
In addition, as the inert gas purge process, for example, when the power generation process is stopped, at least the inert gas is introduced into the CO converter 142. In this introduction, water vapor, water, and vaporized liquid fuel are not present in the reformer 141 or the CO converter 142. Although details of this inert gas purge will be described later, a configuration in which purging is performed in two stages is illustrated. However, when purging with steam in consideration of cooling efficiency, etc., the purge is not performed once after the steam purge. A one-stage process for purging with an active gas or a multi-stage process may be used. Moreover, it is good also as only purging with an inert gas, without steam purging. When purging with steam, it is preferable to purge with an inert gas before the temperature is lowered to a temperature at which steam is condensed. That is, when condensation occurs, there are inconveniences such as taking time to remove moisture and increasing the amount of inert gas used for purging.
Further, as the purge process of the purge air, after the second inert gas purge process, the purge air is sealed in at least the CO converter 142.

[Operation of fuel cell system]
Next, the operation in the fuel cell system 100 described above will be described with reference to the drawings.

(Start process)
First, as an operation in the fuel cell system 100, an activation process that is an operation at the time of activation will be described with reference to FIG.
FIG. 2 is a flowchart showing the control operation of the startup process.

  First, when the control device acquires a signal related to a power generation request, it confirms that each valve is closed, that is, the fuel supply valve 112B of the liquid fuel supply path 112, the desulfurization fuel valve 122A of the desulfurization fuel path 122, and the first supply. The first valve 182C1 of the pipe 182C, the second valve 182D1 of the second supply pipe 182D, the circulation valve 191A of the circulation path 191, the transfer valve 133D of the water supply path 133, the air valve 153 of the oxygen-containing gas supply means 150, the air supply path 145 The air supply valve 145B, the open / close valve 146A of the fuel gas supply path 146, the switching valve 165A of the bypass path 165, the fuel gas valve 163A of the fuel gas supply path 163, and the third valve 182E1 of the third supply pipe 182E are controlled to be closed. . Further, the connection portion of the three-way valve 182A with the inert gas supply pipe 182B and the connection portion with the purge air supply pipe 182F are controlled to be closed. The signal related to the power generation request includes input operations such as a switch switching operation by the user, timer control for recognizing that the time measuring means for measuring the current time has reached a preset time, and power consumption in the power load. Examples thereof include a signal accompanying a start or an increase in power consumption, a signal accompanying a decrease in the storage amount of the reduced storage battery, and the like.

And a control apparatus implements the inert gas purge process which supplies an inert gas with the purge gas supply means 180 at 50 degrees C or less, and makes the state which at least does not have air in the CO converter 142 at a temperature higher than 50 degreeC. (Step S101). Here, since combustion by the burner 141A is stopped at the time of the stop process, the CO converter 142 is at a normal room temperature, that is, a temperature of 50 ° C. or less when the inert gas purge process of step S101 at the time of startup is performed. ing.
In the inert gas purge process of step S101, the control device opens the connection portion of the three-way valve 182A of the purge gas supply path 182 with the inert gas supply pipe 182B and the first valve 182C1, and is stored in the inert gas tank 181. The inert gas thus supplied is supplied to the downstream side of the desulfurization means 120, and the switching valve 165A of the bypass path 165 is opened.
Specifically, the inert gas is supplied to the desulfurization fuel valve 122A and the vaporizer 131 in the desulfurization fuel path 122 via the inert gas supply pipe 182B and the first supply pipe 182C. By supplying the inert gas, the inert gas sequentially flows into the reformer 141, the CO converter 142, and the CO selective oxidizer 143 via the desulfurization fuel path 122 and the vaporizer 131, and the remaining air is bypassed. It is made to flow through so that it may push out to burner 141A via 165. By this flow, even if Cu of the CO shift catalyst is oxidized, it is immediately reduced.
Then, after supplying a certain amount of inert gas, the control device supplies, for example, the capacity of the reformer 141, the CO converter 142, and the CO selective oxidizer 143, and then switches the switching valve 165A of the bypass path 165. In addition to the closed state, the circulation valve 191A of the circulation means 190 is opened to drive the circulation blower 193 so that the inert gas circulates in the circulation path 191. Further, the control device further supplies an inert gas having a capacity equivalent to the capacity of the circulation path 191, and then closes the connection portion of the three-way valve 182 </ b> A of the purge gas supply path 182 with the inert gas supply pipe 182 </ b> B to close the inert gas tank. The supply of the inert gas from 181 is stopped, and the inert gas is circulated in the circulation path 191.

Further, the control device performs a warming process (step S102).
That is, the control device operates a starting heater (not shown) to heat the burner 141A. Further, the control device opens the air supply valve 145B of the air supply path 145, drives the air supply blower 145A, and supplies combustion air to the burner 141A of the reformer 141. Further, the control device drives the cooling water circulation pump 178A of the cooling water circulation path 178 to circulate the pure water 133A stored in the pure water tank 133B through the cooling device 177, the heat exchanger 178B, and the pure water tank 133B.

  After the warm-up process in step S102, the control device confirms the temperature state of the burner 141A (step S103). When the controller recognizes that the burner 141A has warmed to a certain temperature, it drives the transport pump 144A in the fuel transport path 144 to supply the liquid fuel 111A stored in the liquid fuel storage tank 111 to the burner 141A. Then, the igniter (not shown) of the burner 141A is operated to burn the liquid fuel 111A to heat the reformer 141.

Further, the control device detects the flame temperature of the burner 141A. When the control device recognizes that the flame detection temperature of the burner 141A has reached a predetermined temperature (step S104), each of the reformer 141, the CO converter 142, and the CO selective oxidizer 143 of the reforming unit 140 is detected. It is detected whether the temperature has reached a predetermined temperature. Then, the control device recognizes that each reforming unit 140 has reached a predetermined temperature. Specifically, the temperature of the reformer 141 is 550 ° C. or more, and the CO shift catalyst of the CO shift converter 142 generates CO. When it is recognized that the reaction temperature has reached 250 ° C. or higher, which is the reaction temperature for transformation (step S105), the circulation blower 193 is stopped and the circulation valve 191A is closed, and the reforming process is performed (step S106).
That is, in the reforming process of step S106, the control device opens the desulfurization fuel valve 122A of the desulfurization fuel path 122 of the desulfurization means 120, drives a desulfurization fuel pump (not shown), and stores it in the buffer tank of the desulfurization means 120. The desulfurized liquid fuel 111A is supplied to the vaporizer 131 of the vaporization means 130. Further, the control device opens the fuel supply valve 112B of the liquid fuel supply path 112 and drives the liquid fuel pump 112A to supply the liquid fuel 111A stored in the liquid fuel storage tank 111 to the desulfurizer 121 of the desulfurization means 120. The fuel is supplied through the fuel supply pipe 112C. By supplying the liquid fuel 111A to the desulfurizer 121, the liquid fuel 111A adsorbs and removes sulfur compounds contained by contact with the desulfurizing agent and flows into the buffer tank.
In addition, the control device opens the transfer valve 133D of the water supply path 133 and drives the transfer pump 133C of the water supply path 133 of the vaporizing means 130 so that the pure water 133A stored in the pure water tank 133B is heat exchange apparatus 132. To supply. By supplying the pure water 133A, steam is generated by heat exchange with the exhaust gas from the reformer 141 in the heat exchange device 132 and supplied to the vaporizer 131. Due to the supply of the liquid fuel 111A to the vaporizer 131 and the supply of water vapor from the heat exchange device 132 to the vaporizer 131, the liquid fuel 111A is mixed with the vapor and vaporized to be reformed by the reforming unit 140 as a vaporized liquid fuel. To the device 141. Until the vaporized liquid fuel is supplied to the reforming unit 140, the circulation valve 191A may be opened and the remaining inert gas may be recovered by the storage means 192.
Then, the control device opens the switching valve 165A of the bypass path 165, and supplies the gas that is supplied from the vaporizer 131 as vaporized liquid fuel, is reformed by the reforming unit 140, and flows out, thereby bypassing the bypass path 165 and the fuel gas supply path. 146 to the burner 141A of the reformer 141. That is, the fuel gas processed in an unstable reforming state of the vaporized liquid fuel in the reforming unit 140 is used for combustion for stable heating of the reformer 141.

After the reforming process in step S106, the control device confirms conditions such as the temperatures of the reformer 141, the CO converter 142, and the CO selective oxidizer 143 for the reforming process in the reforming unit 140 ( Step S107). When recognizing that the conditions for the reforming process are satisfied in step S107, the oxidation blower 143A is driven to supply air to the CO selective oxidizer 143. By supplying this air, CO that remains without being transformed by the CO transformer 142 is oxidized to CO ₂ and CO in the fuel gas is removed.
Then, after confirming the reforming process conditions in step S107, it is determined whether or not the reforming unit 140 has stabilized, for example, whether or not a stable time has elapsed. Then, when recognizing that the stabilization time of the reforming unit 140 has elapsed (step S108), the control device performs a power generation process (OCV process) (step S109).

That is, the control device opens the air valve 153 of the oxygen-containing gas supply means 150 and drives the blower 151 to supply air from the pure water tank 133B while heating the air to 60 to 70 ° C. with, for example, a humidifier. Humidified with pure water 133A. Then, the humidified air is supplied to the positive electrode 171 of the fuel cell 170.
Further, the control device closes the switching valve 165A of the bypass path 165 and opens the fuel gas valve 163A of the fuel gas supply path 163, so that the hydrogen-rich fuel gas reformed by the reforming unit 140 is For example, it is humidified with pure water 133A supplied from a pure water tank 133B while being adjusted to 60 to 70 ° C. with a humidifier or the like. Then, the humidified fuel gas is supplied to the negative electrode 172 of the fuel cell 170.
By supplying the humidified air and the fuel gas, in the fuel cell 170, hydrogen of the supplied fuel gas and oxygen in the supplied air react to generate water (pure water 133A), and the positive electrode 171 and DC power is generated between the negative electrodes 172. The control device checks the voltage of the DC power generated in the fuel cell 170 (step S110), converts the generated DC power into AC power via an inverter (not shown) of the control device, and supplies the AC power to the power load ( Step S111). Specifically, the state is switched from a state in which commercial AC power is supplied from the outside to a state in which the fuel cell system 100 is supplied as household power.
In this way, by recognizing that power is generated at a predetermined voltage (step S112), the routine proceeds to steady operation processing (step S113). That is, to control the flow rate of the liquid fuel 111A, to control the electric power supplied to the electric heater that is the heating condition of the desulfurization heating means of the desulfurizer 121, to control the combustion of the burner 141A of the reformer 141, and to generate water vapor in the heat exchange device 132 The operation state of the entire fuel cell system 100 is controlled, such as the supply amount control of the pure water 133A, temperature management, and power generation amount management.

(Stop processing)
Next, as an operation in the fuel cell system 100, a stop process that is an operation at the time of stop will be described with reference to FIG. 3 and FIG.
FIG. 3 is a flowchart showing the control operation of the stop process. FIG. 4 is a graph showing the relationship between the reforming process / purge process and the temperature at the time of starting and stopping.

First, as shown in FIG. 4, when the control device acquires a signal related to a stop request, the control device performs a stop process (step S201). Signals related to this stop request include input operations such as switch switching operations by the user, timer control for recognizing that the time measuring means for measuring the current time has reached a preset time, and a reduction in power consumption at the power load Or the signal accompanying a fall, the signal accompanying the fall of the electrical storage amount of a storage battery, etc. can be illustrated.
That is, the control device cuts off the supply to the power load generated by the fuel cell 170 and switches to a state in which, for example, commercial AC power is supplied. Further, an inverter (not shown) of the control device is turned off. Then, the control device closes the fuel gas valve 163A of the fuel gas supply path 163, and stops the supply of the hydrogen-rich fuel gas reformed by the reforming unit 140 to the fuel cell 170. Further, the control device closes the desulfurization fuel valve 122A of the desulfurization fuel path 122 of the desulfurization means 120, stops driving of a desulfurization fuel pump (not shown), and stores the desulfurized liquid stored in the buffer tank of the desulfurization means 120. The supply of the fuel 111A to the vaporizer 131 is shut off. Further, the control device closes the fuel supply valve 112B of the liquid fuel supply path 112 and stops driving the liquid fuel pump 112A, and supplies the liquid fuel 111A stored in the liquid fuel storage tank 111 to the desulfurizer 121. To stop.

After the stop process in step S201, the control device performs a first inert gas purge process (step S202).
That is, the control device opens the connection portion of the purge gas supply path 182 with the inert gas supply pipe 182B in the three-way valve 182A, the first valve 182C1, the second valve 182D1, and the third valve 182E1, and enters the inert gas tank 181. The stored inert gas is supplied to the downstream side of the desulfurization means 120, and the switching valve 165A of the bypass path 165 is opened.
Specifically, the inert gas is supplied to the desulfurization fuel valve 122A and the vaporizer 131 in the desulfurization fuel path 122 via the inert gas supply pipe 182B and the first supply pipe 182C. By supplying the inert gas, the inert gas mixed with the water vapor in the vaporizer 131 flows into the reforming unit 140, and the reformed gas such as vaporized liquid fuel or fuel gas remaining in the reforming unit 140 is bypassed. Through 165, the gas flows so as to be pushed out to the burner 141A, and the inert gas sequentially flows into the reformer 141, the CO converter 142, and the CO selective oxidizer 143 to be replaced.
Further, the inert gas is supplied to the downstream side of the fuel gas valve 163A in the fuel gas supply path 163 via the inert gas supply pipe 182B and the second supply pipe 182D. By this supply, the fuel gas remaining in the negative electrode 172 of the fuel cell 170 flows through the fuel gas supply path 146 so as to be pushed out to the burner 141A, and the inert gas sequentially flows into the negative electrode 172 of the fuel cell 170. It will be in the state to be replaced (purged).
Further, the inert gas is supplied to the downstream side of the transport pump 144A in the fuel transport path 144 via the first supply pipe 182C and the third supply pipe 182E. The supply of the inert gas causes the liquid fuel 111A remaining on the downstream side of the transport pump 144A in the fuel transport path 144 to be pushed out and burned to the burner 141A, and the inert gas is transported to the transport pump 144A in the fuel transport path 144. More downstream side and burner 141A are sequentially introduced and replaced. This can prevent the liquid fuel 111A remaining due to the residual heat from being solidified or seized.

Then, the control device determines whether or not the first purge of the inert gas is completed, for example, whether or not a predetermined time has elapsed since the start of the supply of the inert gas. When the control device recognizes that the predetermined time has elapsed (step S203), that is, that the reformed gas or fuel gas has been removed from the vaporizer 131 to the negative electrode 172 of the fuel cell 170, the supply of the inert gas is interrupted. To do. That is, the control device closes the connection portion of the purge gas supply path 182 with the inert gas supply pipe 182B in the three-way valve 182A, the first valve 182C1, the second valve 182D1, and the third valve 182E1.
In this state, the reformer 141 is still at a relatively high temperature, so that steam is generated by the heat exchange device 132, supplied to the vaporizer 131, and flows into the reforming unit 140. That is, the inert gas purged in the first inert gas purge process flows to the burner 141A through the bypass path 165 so that the inert gas is pushed out by the steam, and the negative electrode 172 of the fuel cell 170 is purged from the reforming unit 140 by the steam. It will be in a state to be. In this state, the fuel gas valve 163A is controlled to be opened.
The inflow of the steam into the reforming unit 140 accelerates the cooling of the reforming unit 140, particularly the reformer 141. In this water vapor purge, the inert gas may not be allowed to flow through the burner 141A, but may flow into the circulation means 190 and be collected by the storage means 192.
Then, the control device checks conditions such as the temperatures of the reformer 141, the CO converter 142, and the CO selective oxidizer 143, and determines whether or not the temperature has been cooled to a certain level. For example, it is determined whether or not the water vapor purge has been performed for a predetermined time length, and when it is recognized that the water vapor purge has been performed for the predetermined time length (step S204), the transfer valve 133D of the water supply path 133 of the vaporizing means 130 is closed. In addition, the driving of the transport pump 133C is stopped, and the supply of the pure water 133A to the heat exchange device 132 is stopped. By stopping the supply of the pure water 133A, the generation of water vapor is stopped and the water vapor purge is stopped.

Thereafter, the control device performs a second purge of the inert gas.
That is, the control device opens the connection portion of the purge gas supply path 182 with the inert gas supply pipe 182B in the three-way valve 182A and the first valve 182C1. Further, the control device closes the opening / closing valve 146A of the fuel gas supply path 146, opens the circulation valve 191A of the circulation means 190, and drives the circulation blower 193 of the circulation means 190. As a result, the inert gas is supplied to the desulfurized fuel valve 122A and the vaporizer 131 in the desulfurized fuel path 122 via the inert gas supply pipe 182B and the first supply pipe 182C. Due to the supply of the inert gas, the water vapor purged from the vaporizer 131 to the negative electrode 172 of the fuel cell 170 flows into the storage means 192 through the circulation path 191 so as to be pushed out. The water vapor flowing into the storage means 192 is cooled and deposited as water (pure water 133A) and is retained in the storage means 192. Note that the inert gas that sufficiently pushes out the water vapor and flows out from the negative electrode 172 of the fuel cell 170 also flows into the storage unit 192 through the circulation path 191, and the water vapor or water (pure water 133A) is vented to the gas-liquid separation unit 192A. After being removed by the trap, it is returned to the inert gas supply position by the circulation blower 193 and circulated.
Then, the control device determines whether or not the second purge of the inert gas is completed, for example, whether or not a predetermined time has elapsed since the start of the supply of the inert gas. Then, when the control device recognizes that the predetermined time has elapsed (step S205), that is, the inert gas is returned to the first supply pipe 182C and circulates, the control device 182A in the purge gas supply path 182 is inactivated. The supply from the connection portion with the active gas supply pipe 182B is stopped, and only the already supplied inert gas is circulated.

Thereafter, when the control device recognizes that the predetermined time has elapsed, that is, that the reforming unit 140 has been cooled to 50 ° C. or less, it performs an air purge process.
That is, the control device opens the connection portion of the three-way valve 182A with the purge air supply pipe 182F and drives the purge blower 183. Thus, the purge air is supplied to the desulfurization fuel valve 122A and the vaporizer 131 in the desulfurization fuel path 122 via the purge air supply pipe 182F and the first supply pipe 182C. By supplying the purge air, the inert gas purged from the vaporizer 131 to the negative electrode 172 of the fuel cell 170 flows into the storage means 192 through the circulation path 191 so as to be pushed out. The purge air that sufficiently pushes out the inert gas and flows out from the negative electrode 172 of the fuel cell 170 also flows into the storage means 192 through the circulation path 191 and is returned to the purge air supply position by the circulation blower 193. Circulated.
Then, the control device determines whether or not purging of the purge air is completed, for example, whether or not a predetermined time has elapsed since the supply of the purge air was started. When the control device recognizes that the predetermined time has elapsed (step S206), that is, the purge air is returned to the first supply pipe 182C and circulates, the purge air is sealed. Specifically, the control device closes the connection portion of the three-way valve 182A with the purge air supply pipe 182F, the first valve 182C1, the circulation valve 191A, the fuel gas valve 163A of the fuel gas supply path 163, and the switching valve 165A. At the same time, driving of the purge blower 183 and the circulation blower 193 is stopped to stop the circulation of the purge air, and the gas from the vaporizer 131 to the negative electrode 172 of the fuel cell 170 is purged with the purge air. Further, the control device closes the air valve 153 of the oxygen-containing gas supply unit 150, stops the driving of the blower 151, and stops the supply of air to the positive electrode 171 of the fuel cell 170. Further, the control device closes the air supply valve 145B of the air supply path 145 and stops the driving of the air supply blower 145A, stops the supply of combustion air to the burner 141A, and the fuel cell system 100 Suspended.

{Operational effect of fuel cell system}
As described above, in the fuel cell system 100 of the above embodiment, when starting the power generation process, the inert gas is introduced into the CO conversion container at 50 ° C. or less.
For this reason, since the CO conversion catalyst is not exposed to the air atmosphere when the temperature becomes 50 ° C. or higher at the start of the CO conversion treatment, CuO is not newly generated, and the temperature of 50 ° C. or higher is not generated. When reduced at temperature, Cu of the CO shift catalyst does not aggregate. Accordingly, the deactivation of the CO shift catalyst due to copper aggregation can be suppressed, and a good carbon monoxide shift treatment can be stably obtained for a long period of time. In particular, it is preferable because a stable catalytic activity can be obtained for a long period of time even in a small home-use configuration in which starting and stopping are frequently repeated.
Further, nitrogen gas, which is widely used, is used for purging.
For this reason, even if it constructs | assembles as a home system, for example, supply of nitrogen gas can be performed easily and expansion of utilization is obtained easily.
Furthermore, a dry inert gas is introduced.
For this reason, for example, the CO conversion catalyst is oxidized by water vapor at the time of temperature reduction at the time of stopping the CO conversion treatment, condensed moisture after cooling, etc., and CO at a temperature exceeding about 200 ° C. by heating at the start of the conversion treatment. By abruptly reducing the shift catalyst, it is possible to prevent the activity of the copper of the CO shift catalyst from agglomerating and decreasing. Therefore, good activity can be stably obtained for a long time.

Further, a reformer 141 that generates a reformed gas by supplying vaporized liquid fuel generated by mixing water vapor into the liquid fuel 111A after desulfurization from the raw material gas supplying means by the circulation means 190 of the purge gas supplying means 180, and this At least one of a CO converter 142 that converts CO in the reformed gas generated by the reformer 141, and a fuel cell 170 that generates power using the reformed gas whose CO has been converted by the CO converter 142 The gas obtained by gas-liquid separation of the effluent flowing out from one of them, specifically, the supplied inert gas which is the effluent flowing out from the fuel cell 170, is converted into a reformer 141 and a CO converter 142. To return.
For this reason, even when the liquid fuel 111A, which is the raw material of the fuel cell 170, is purged with the liquid fuel 111A and coated with the reforming catalyst, the liquid fuel 111A that cannot perform its catalytic function is used as the raw material. The inert gas is circulated by supplying the gas from the desulfurization unit 120 to the downstream position by the circulation unit 190 in a state where the gas flows out from the fuel cell 170. Therefore, it is not necessary to supply a new inert gas, it is sufficient to supply a minimum amount of the inert gas, and the inert gas can be reused with a simple configuration for returning the supplied inert gas. The gas can be purged at a stable and efficient operation stop time, and an efficient operation can be provided. Further, even when the inert gas is supplied in a somewhat excessive amount for purging with the inert gas, the excess is recovered by the storage means 192, or the inert gas remaining at the time of restarting is circulated to the circulation means 190 to be stored. Further effective utilization of the inert gas such as recovery at 192 is easily achieved, and more efficient operation control is obtained.
Furthermore, since the amount of inert gas used for purging can be reduced, for example, the frequency of filling an inert gas tank filled with an inert gas can be reduced, and maintenance management is facilitated. For this reason, for example, the frequency of replacement of the inert gas tank is reduced due to a decrease in the filling frequency of the inert gas, and a small inert gas tank can be used, so that a small system configuration that can be installed for home use can be easily constructed.
A gas-liquid separation means 192A for gas-liquid separation of the effluent flowing out of the fuel cell 170 by purging with an inert gas is provided in the circulation means 190, and the separated gas is supplied downstream from the desulfurization means 120.
For this reason, for the vaporization and steam reforming of the water by the humidification at the time of power generation that flows out as an effluent by supplying an inert gas and purging, the water that is the reaction product in the fuel cell 170, the liquid fuel 111A Water derived from water vapor or the like to be mixed is separated and removed, and it is easy to circulate a dry inert gas with a simple configuration, and the reforming capacity of the reforming unit 140 is reduced by returning water, that is, a catalyst. It is possible to prevent a decrease in function and the like, and a good stop state can be easily obtained.
In particular, an inert gas is supplied not only from the CO converter 142 but also from the upstream side of the reformer 141 and flows through the reformer 141 and further through the CO selective oxidizer 143. Therefore, the loss occurs due to oxidation of the reformer 141. The activity of the active reforming catalyst, CO selective oxidation catalyst, and the like can be lowered, and the operation can be performed in a series of processes in which an inert gas is circulated, so that an overall stable process can be easily obtained.

In addition, the purge gas supply unit 180 performs the first purge process in which the inert gas is supplied for a predetermined time after the supply of the liquid fuel 111A desulfurized by the desulfurization unit 120 is stopped, and then the inert gas is resupplied after the predetermined time has elapsed. The second purge step is performed.
For this reason, after the supply of the liquid fuel 111A is stopped, the inactive gas purge causes inconvenience such as carbonization, scorching, and blockage due to the liquid fuel 111A and the reformed gas derived from the liquid fuel 111A remaining in the reforming unit 140 and the like. In this case, the supply of the inert gas is temporarily interrupted, and, for example, the reforming unit 140 is rapidly cooled by supplying the reforming unit 140 with the steam supplied by the vaporization means 130 to reform the liquid fuel 111A. The inert gas is re-supplied after the elapse of a predetermined time such as before the reforming unit 140 is cooled to some extent and the water vapor is precipitated as water, and the water is deposited and modified as described above due to the residual water vapor. Inconveniences such as deterioration of quality characteristics can be prevented, and operation can be stopped quickly and efficiently. Furthermore, a steam purge is performed for rapid cooling of the reformer 141, and the second purge process is performed after the steam purge in order to prevent inconvenience due to condensation from the steam. There is no water vapor, the reduced state of the catalyst can be maintained, and a stable treatment can be obtained for a longer period of time.

The purge gas supply means 180 supplies an inert gas upstream from the vaporization means 130 and downstream from the desulfurization means 120.
For this reason, for example, in the portion upstream of the vaporization means 130 in which the liquid fuel 111A flows in the desulfurized fuel path 122 in the liquid phase, the liquid fuel 111A remains when the supply of the liquid fuel 111A is shut down to stop the operation. This can prevent the inconvenience such as carbonization of the remaining liquid fuel 111A due to the residual heat of the reforming unit 140. Furthermore, as described above, a series of purges of the reformer 141, the CO converter 142, and the CO selective oxidizer 143 are obtained, and an overall stable treatment for a long period of time can be easily obtained.

Further, the purge gas supply means 180 supplies an inert gas downstream from the desulfurization means 120, and at the downstream side of the reforming unit 140, upstream from the fuel cell 170, that is, downstream from the fuel gas valve 163A in the fuel gas supply path 163. To the side.
For this reason, the region of the fuel cell 170 on the downstream side of the reforming unit 140 that does not cause any inconvenience even if water derived from water vapor precipitates, and the reforming unit 140 side that causes inconvenience such as deterioration in reforming characteristics due to water remaining. In this region, a configuration in which an inert gas is supplied independently can be obtained. Therefore, the amount of inert gas used is supplied by supplying steam to the region on the reforming unit 140 side for rapid cooling in the reforming unit 140 and re-supplying the inert gas for discharging the steam. Can be further reduced, and more efficient operation can be obtained.

The fuel burned by supplying the effluent flowing from the fuel cell 170 to the burner 141A that is heated to reform the liquid fuel 111A vaporized by the vaporization means 130 in the reforming unit 140. A circulation unit 190 is connected to the gas supply path 146 to supply the inert gas supplied in the second purge step, which is an effluent, to the downstream side of the desulfurization unit 120.
For this reason, the supply of the liquid fuel 111A is stopped and hydrogen gas or carbon monoxide, which is an effluent flowing out of the fuel cell 170 by purging with the inert gas, is burned by the burner 141A to improve energy efficiency and carbon monoxide. In this way, it is possible to prevent the destruction of the environment due to the exhaust gas, and to supply the water vapor and the inert gas component flowing out from the fuel cell 170 by purging the inert gas after supplying the water vapor to the reforming unit 140 for quick cooling. The gas-liquid separation unit 192A separates and removes the water vapor, and only the dry inert gas is supplied and circulated, so that a good and efficient operation can be performed from the fuel gas supply path 146 through the circulation unit. It can be easily obtained with a simple configuration for branching 190.

Further, an inert gas is also supplied to a fuel conveyance path 144 that supplies liquid fuel burned by the burner 141A for heating in the reforming unit 140 to the burner 141A.
Thus, when the operation is stopped, the supply of the liquid fuel 111A is stopped and the heating by the burner 141A is stopped, so that the liquid fuel 111A remaining in the fuel transfer path 144 for supplying the liquid fuel 111A to the burner 141A is an inert gas. Therefore, inconveniences such as carbonization of the remaining liquid fuel 111A due to residual heat of the reforming unit 140 can be prevented, and stable and good operation can be obtained.

In addition, overall control is performed by the control device.
For this reason, temperature, flow rate, valve opening / closing timing, pump drive stop timing, etc. can be controlled relatively easily.For example, it is easy to construct inert gas purge and circulation control by software program control etc. Automatic control can be easily performed as a home system in which stop and start are performed relatively frequently.
Note that the control device is not limited to a single form such as a plurality of circuit boards, and various forms such as a structure in which a plurality of control circuits are constructed as a network can be applied.

[Modification of Embodiment]
The aspect described above shows one aspect of the present invention, and the present invention is not limited to the above-described embodiment, and within the scope of achieving the objects and effects of the present invention. Needless to say, the modifications and improvements are included in the contents of the present invention. In addition, the specific structure and shape in carrying out the present invention may be used as other structures and shapes within the scope of achieving the object and effect of the present invention.

In other words, the fuel cell system of the present invention is not limited to the configuration in which the operation is controlled by the control device, but may be configured to be controlled for each configuration of the desulfurization means 120, the vaporization means 130, the reforming unit 140, and the like.
In addition, as a control configuration, any configuration can be configured, such as a configuration in which valve opening / closing and pump or blower drive control are performed by software signal control as a general control, or a configuration in which control is performed by hardware of each configuration. Applicable.

  Then, the inert gas is supplied immediately after obtaining the signal relating to the power generation request, but it is determined whether or not at least the temperature of the CO transformer 142 is 50 ° C. or less, and if it is determined that the temperature is 50 ° C. or less, the inert gas It is good also as a structure which supplies.

  Further, a hydrogen-rich dry reformed gas may be introduced instead of the inert gas as the gas introduced at least to the CO converter 142 at 50 ° C. or lower.

  In addition, when the CO transformer 142 is purged with air, the air supplied from the oxidation blower 143A may be used. In such a configuration, it is not necessary to use the purge blower 183 and the purge air supply pipe 182F, and the configuration can be simplified.

  Furthermore, although the configuration in which at least the CO transformer 142 is purged with air is illustrated, a configuration in which no air purge is performed may be employed. In such a configuration, it is not necessary to use the purge blower 183 and the purge air supply pipe 182F, and the configuration can be simplified. Further, it is not necessary to perform the process of step S206 accompanying the air purge process during the stop process, and the control in the stop process can be facilitated.

And although it was set as the structure which heats and desulfurizes the liquid fuel 111A, the structure which desulfurizes at normal temperature, for example, without heating can also be applied. In such a configuration, a buffer tank or the like can be omitted, and energy consumption for heating can be prevented.
In addition, vaporization of the liquid fuel 111A is not limited to steam mixing, but may be performed by various methods such as vaporizing directly by heat exchange with the exhaust gas from the reforming unit 140, separately mixing steam, using an ejector, etc. A vaporizer can be used.
Furthermore, although the reformer 141, the CO converter 142, and the CO selective oxidizer 143 have been described as an integral configuration as the reforming unit 140, they may be configured separately.
Further, the fuel cell 170 is not limited to the solid polymer type, and other various configurations can be applied.

The second supply pipe 182D has been described, but only the first supply pipe 182C may be provided, and the inert gas or purge air may not be supplied between the reforming unit 140 and the fuel cell 170.
With this configuration, the system configuration can be further simplified, the control can be easily performed, the system construction can be further improved, and the size can be further reduced.
In such a configuration, the bypass path 165 may not be provided.

Further, although the storage unit 192 is provided as the circulation unit 190, for example, the storage unit 192 may not be provided, and only the gas-liquid separation unit 192A such as the separator 175 that is a separator may be provided.
Furthermore, the gas-liquid separation means 192A is not provided, and, for example, as a configuration that dissipates heat without insulating the piping of the circulation path 191, when circulating, the water vapor is cooled to become water and separated by the drain provided in the piping. Etc.

Then, as a purge of the inert gas, for example, the first purge step is not performed, and only the water vapor is supplied, and then the reducing gas of the present invention is reduced before the temperature of the CO converter 142 falls below the water condensation temperature. The second purge step, which is the supply of at least one of the inert gases, may be performed only.
In this case, the remaining liquid, such as preventing the residual heat from the reforming unit 140 from being transmitted upstream of the vaporizing means 130 or returning the staying liquid fuel 111A to the liquid fuel storage tank 111. It is preferable not to cause inconvenience such as carbonization of the fuel 111A.
Further, when inert gas is stored in the circulation path 191 during purging of the inert gas, the stored inert gas is supplied by opening and closing the valve as appropriate to purge the reformed gas and water vapor. May be.

Furthermore, although the configuration of purging from the reforming unit 140 to the negative electrode 172 of the fuel cell 170 at the time of stoppage is illustrated, the following configuration may be used.
For example, when stopping, only the reforming unit 140 is purged. Here, when purging only the reforming unit 140, only the reformer 141 may be purged, or the CO converter 142 and the CO selective oxidizer 143 may be purged. In the reforming step, the fuel gas valve 163A and the opening / closing valve 146A are closed, and the switching valve 165A is opened, so that water vapor, liquid removal gas filled in the reforming unit 140, and the like are supplied to the fuel cell 170. Without being supplied to the negative electrode 172, only the burner 141A is supplied and burned. Thereafter, after a lapse of a predetermined time, for example, a time when all of the liquid removal gas is combusted, the fuel gas valve 163A and the opening / closing valve 146A may be opened. In addition to combustion, for example, the reforming unit 140 may separately store or circulate until a predetermined temperature is reached and CO can be removed.
With such a configuration that only the reforming unit 140 is purged, even if the liquid removal gas or the like charged in the reforming unit 140 before starting contains CO, this CO is the fuel. Since it is burned by the burner 141A without being supplied to the negative electrode 172 of the battery 170, deterioration of the negative electrode 172 can be prevented.

  Moreover, you may distribute | circulate independently as a control program of a control apparatus.

  In addition, the specific structure and shape in the implementation of the present invention may be other structures as long as the object of the present invention can be achieved.

〔Example〕
Next, an Example is given and this invention is demonstrated more concretely.
In addition, this invention is not limited to the content of an Example etc. at all.

(Change in redox state over time)
First, various purge gases are supplied under the conditions of Experiments 1 to 4 below, and the structural change of the CO conversion catalyst is changed to an In-situ XAFS (X-ray Absorption Fine Structure: X-ray Absorption Fine Structure) at the Cu-K shell absorption edge. ), And the measurement results were analyzed to determine the change over time in the redox state.
The beam line used is BL01B1 of JASRI (Japan Synchrotron Radiation Research Institute) SPring-8. Then, in this beam line, as shown in FIG. 5, an experimental device 300 including a heatable quartz cell 310 and a supply line 320 for supplying hydrogen gas, helium gas, air, and water vapor is installed. Various purge gases were supplied while being heated for treatment, and the oxidation-reduction state of the catalyst was observed. As the CO conversion catalyst, a Cu—ZnO—Al ₂ O ₃ catalyst (trade name: MDC-7, manufactured by Zude Chemie) was used.
Water vapor is vaporized by supplying deionized water to a vaporizer 340 heated to 200 ° C. using a precision liquid delivery pump 330 for LC (Liquid Chromatography) and mixed as a feed gas to the cell 310. Supplied to.
And, by these treatments, the structural change of the CO shift catalyst in the cell 310 was analyzed by the Quick-XAFS method. This analysis was performed using a Si (111) 2 crystal spectrometer with a measurement angle (θ) ranging from 13.2 [deg] to 10.7 [deg] (8658 eV to 10649 eV) at 0.0005 deg / step intervals. Measurement was performed under the condition of 50 seconds per scan.
For data analysis, XAFS analysis software (trade name: REX2000) manufactured by Rigaku Corporation was used. The XANES (X-ray Absorption Near Edge Structure) region of the obtained XAFS spectrum was subjected to pattern fitting using a standard sample to analyze the redox state of Cu of the CO shift catalyst. Moreover, the vibration structure of the EXAFS (Extend X-ray Absorption Fine Structure) region is Fourier transformed, and the Cu-Cu bond in the first coordination sphere of metal Cu is extracted from the obtained radial distribution function, and the inverse Fourier transform is performed. By performing curve fitting later, an average coordination number of Cu—Cu bonds in the first coordination sphere was calculated, and the aggregation state of Cu was analyzed. CuO, Cu (OH) ₂ , Cu ₂ O, and Cu-foil were used as standard samples for XANES spectrum analysis, and Cu-foil (coordination distance: 2.556 mm, coordination was used to calculate the average coordination number from the EXAFS spectrum. Number: 12) was used as a standard sample.

[Change in redox state over time in Experiment 1]
Experiment 1 was an apparatus in which the experimental device 300 shown in FIG. 5 was installed, and the CO shift catalyst was treated in an atmosphere and temperature as shown in FIG. That is, the temperature was raised from around 80 ° C. to around 230 ° C. in a hydrogen atmosphere (H ₂ / inert gas (He)).
At this time, as shown in FIG. 6 (B), Cu (OH) ₂ and CuO are present up to about 150 ° C. However, when the temperature is further raised to about 230 ° C., these are reduced and Cu is reduced to about It was confirmed that 85% and about 15% Cu ₂ O were present.

[Change in redox state over time in Experiment 2]
In Experiment 2, the CO shift catalyst was treated at the atmosphere and temperature as shown in FIG. That is, after Experiment 1, in order to simulate the reaction, water vapor (H ₂ O) was supplied and replaced with a hydrogen water vapor atmosphere (H ₂ / He / H ₂ O), and the temperature was raised to around 250 ° C. .
At this time, as shown in FIG. 6B, it was recognized that Cu increased to about 90% and Cu ₂ O decreased to about 10%.

[Change in redox state over time in Experiment 3]
In Experiment 3, the CO shift catalyst was treated at the atmosphere and temperature as shown in FIG. That is, under the same conditions as in Experiment 2 (about 250 ° C. hydrogen steam atmosphere with about 90% Cu and about 10% Cu ₂ O), the supply of H ₂ was stopped while maintaining the vicinity of 250 ° C. The atmosphere (He / H ₂ O) was replaced, and after about 2 hours, the supply of H ₂ was resumed while maintaining the vicinity of 250 ° C. to return to the hydrogen water vapor atmosphere.
At this time, as shown in FIG. 7B, when the supply of H ₂ is stopped and replaced with a water vapor atmosphere, Cu is gradually oxidized, Cu is reduced to about 40%, and Cu ₂ O is about 60%. It was observed to increase to%. Furthermore, when the supply of H ₂ is restarted and returned to the hydrogen water vapor atmosphere, Cu ₂ O is reduced, and after about 20 minutes, Cu increases to about 90% and Cu ₂ O decreases to about 10%. ₂ It was recognized that the ratio returned to the ratio before the supply was stopped.

[Change in redox state over time in Experiment 4]
In Experiment 4, the CO shift catalyst was treated at the atmosphere and temperature as shown in FIG. That is, under the same conditions as in Experiment 2, the temperature was lowered to around 50 ° C. while being replaced with an inert gas atmosphere (He). And after substituting with air atmosphere (Air) and maintaining around 50 ° C. for a predetermined time, the temperature was raised to around 250 ° C. while maintaining the air atmosphere, and the atmosphere was returned to the inert gas atmosphere while maintaining around 250 ° C. . Further, after a predetermined time, the supply of H ₂ was restarted and replaced with a hydrogen atmosphere.
At this time, as shown in FIG. 8 (B), it was recognized that the ratio of Cu and Cu ₂ O did not change even when the temperature was reduced to around 50 ° C. in an inert gas atmosphere and then replaced with an air atmosphere. . Further, when the temperature is raised to about 250 ° C. in an air atmosphere, Cu is reduced to about 42% and Cu ₂ O is increased to about 34% due to oxidation of Cu by oxygen with oxygen. It is observed that Cu and Cu ₂ O are present in about 24%, and thereafter, Cu and Cu ₂ O decrease to about 15% and about 32%, respectively, and CuO increases to about 53%. It was. Furthermore, it was recognized that the ratio of Cu ₂ O, CuO, and Cu did not change when the atmosphere was returned to an inert gas atmosphere at around 250 ° C. Further, it was confirmed that when the atmosphere was returned to a hydrogen atmosphere, Cu increased to about 90%, Cu ₂ O decreased to about 10%, and CuO disappeared, returning to the ratio before oxygen oxidation.

(Coordination number and average crystallite diameter of Cu-Cu bond during redox)
Next, the average crystallite diameter was calculated from the average coordination number of the Cu—Cu bond calculated based on the XAFS measurement result of the CO shift catalyst after each of the above experiments 1 to 4. Cu bond is f. c. It is known to have a c structure, and the relationship between the crystallite size and the average coordination number of the Cu-Cu bond can be calculated assuming that the crystallite shape of the Cu particles on the CO conversion catalyst is a cube-octahedron model. It is. For comparison, the structural change of the CO conversion catalyst after each of the following experiments 5 and 6 was analyzed from the XAFS measurement results, and the average coordination number of Cu-Cu bonds, the average crystallite diameter, Asked.

  Here, first, an implementation method of Experiments 5 and 6 will be described. Since Experiments 5 and 6 are substantially equal, Experiment 5 will be described in detail, and for Experiment 6, differences from Experiment 5 will be described.

[Method of performing Experiment 5]
Experiment 5 was conducted using a fixed bed flow apparatus 210 as shown in FIG. The experimental apparatus 200 includes a reaction gas line 220 that supplies a reforming simulation gas and water, a purge gas line 230, an electric furnace 240 that includes a fixed bed circulation device 210, and an analyzer that uses gas chromatography. 250. The same CO conversion catalyst as that used in Experiments 1 to 4 was used as the CO shift catalyst charged in the fixed bed flow apparatus 210.
The operating conditions of the experimental apparatus 200 include a reaction gas having a composition ratio of H ₂ : CO: CO ₂ : H ₂ O = 50: 10: 10: 30, GHSV (Gas Hourly Space Velocity) = 2500. ^-1 was supplied from the reaction gas line 220 to the fixed bed circulation device 210 and reacted at 180 ° C. As an operating condition, starting / stopping (DSS) of the experimental apparatus 200 is performed by switching the reaction gas to water vapor while lowering the temperature, holding it at a temperature of 50 ° C. or lower for 6 hours, and then raising the temperature again to reach a reaction temperature of 180 ° C. It was set as the process switched to the reactive gas supplied from the reactive gas line 220 at ° C. And such a process was repeated 50 times.

[Method of performing Experiment 6]
In Experiment 6, instead of the process of switching the reaction gas to water vapor when the temperature drops in Experiment 5, the process of switching to air (Air) is performed. And start-up / stop was repeated 50 times.

[Coordination number and average crystallite of Cu—Cu bond of CO conversion catalyst after Experiments 1-6]
Next, the coordination number of Cu—Cu bonds and the average crystallite of the CO shift catalyst after the experiments 1 to 6 will be described.
As described above, the coordination number of Cu—Cu bond of Cu and the average crystallite diameter were determined based on the measurement results by XAFS of the CO conversion catalyst after the experiments 1 to 6. The results are shown in Table 1.

From the results shown in Table 1, it was confirmed that the coordination number and the average crystallite diameter after the execution of the experiment 3 were substantially equal to those after the execution of the experiment 2. That is, even when the CO shift catalyst was exposed to a steam atmosphere at 250 ° C. to be oxidized and then reduced by exposure to a hydrogen steam atmosphere, it was confirmed that Cu was not aggregated as before the oxidation. This is presumably because when oxidation and reduction is performed at a relatively high temperature in an atmosphere in which no air exists, only Cu ₂ O is generated as shown in FIG.
Further, it was confirmed that the coordination number and the average crystallite diameter after the experiments 4 to 6 were larger than those after the experiments 2 and 3. That is, when the CO shift catalyst was heated in an air atmosphere at 50 ° C. or higher to be oxidized and then reduced, Cu was found to be aggregated as compared to before oxidation. This is because when oxidized in an air atmosphere of 50 ° C. or higher, it is exposed to a more severe oxidizing atmosphere, and as shown in FIG. 8B, CuO is also generated in addition to Cu ₂ O. This is probably because CuO promotes aggregation of Cu.
From the above, when stopping the CO shift treatment using the CO shift catalyst, at least one of the reducing gas and the inert gas is allowed to flow through the CO shift catalyst at 50 ° C. or lower, and 50 ° C. By eliminating the risk that the CO conversion catalyst will be exposed to the air atmosphere when the above is reached, CuO will not be generated even when the temperature is raised when starting the CO conversion treatment, and when the reduction is performed It turns out that aggregation of Cu does not arise.

  INDUSTRIAL APPLICABILITY The present invention can be used for a purge process in a fuel cell system that generates power using a liquid fuel such as kerosene or a hydrocarbon raw material such as liquefied petroleum gas.

1 is a block diagram illustrating a schematic configuration of a fuel cell system according to an embodiment of the present invention. It is a flowchart which shows the operation | movement of the starting process in the said one Embodiment. It is a flowchart which shows the operation | movement of the stop process in the said one Embodiment. It is a graph which shows the relationship between the reforming process / purge process and the temperature when starting and stopping. It is a figure which shows schematic structure of the experiment device which implements Experiment 1-Experiment 4 of the time-dependent change of the oxidation-reduction state of the CO conversion catalyst for demonstrating this invention. It is a timing chart of the said experiment 1 and the said experiment 2, (A) represents atmosphere and temperature, (B) represents an abundance ratio. It is a timing chart of the said experiment 3, (A) represents atmosphere and temperature, (B) represents an abundance ratio. It is a timing chart of the said experiment 4, (A) represents atmosphere and temperature, (B) represents an abundance ratio. It is a figure which shows schematic structure of the experimental apparatus which implements Experiment 5 and Experiment 6 for demonstrating this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Fuel cell system 110 ... Liquid fuel supply means which comprises raw material gas supply means 111A ... Liquid fuel as hydrocarbon raw material 120 ... Desulfurization means which constitutes raw material gas supply means 130 ... Constructs raw material gas supply means Vaporizing means 141... Reformer as reforming means 142... CO converting device as CO converting device 150... Oxygen-containing gas supplying means 170... Fuel cell 180. Supply means 190 ... Circulation means that also functions as an introduction gas supply means

Claims (11)

A reformed gas mainly composed of hydrogen gas (H ₂ ) generated by reforming a raw material gas containing a hydrocarbon raw material is introduced, and carbon monoxide (CO) remaining in the reformed gas is introduced. A CO conversion device filled with a copper-based CO conversion catalyst that converts to carbon dioxide (CO ₂ ),
A shift vessel filled with the CO shift catalyst to allow the reformed gas to flow;
When the process of introducing the reformed gas into the shift vessel and converting the CO is started, at least one of a reducing gas and an inert gas is introduced into the shift vessel at 50 ° C. or lower. A control device;
CO conversion apparatus characterized by comprising. The CO converter according to claim 1,
The control device causes the at least one gas to be introduced into the shift container before starting the process of converting the CO. The CO converter according to claim 1 or 2, wherein
The control device introduces a purge gas into the shift vessel and fills it when stopping the process of introducing the reformed gas and converting the CO. A CO converter according to any one of claims 1 to 3,
The CO conversion device, wherein the control device fills the reformed gas as the reducing gas. The CO converter according to any one of claims 1 to 4,
The CO conversion device, wherein the control device is filled with a dry gas as the at least one gas. Carbon monoxide (CO) remaining in the reformed gas mainly composed of hydrogen gas (H ₂ ) generated by reforming the raw material gas containing the hydrocarbon raw material is converted by a copper-based CO conversion catalyst. A CO conversion method for converting to carbon dioxide (CO ₂ ),
CO at the time of starting the process which transforms CO in the reformed gas, at least one of a reducing gas and an inert gas is allowed to flow through the CO shift catalyst at 50 ° C. or lower. Transformation method. Reforming means for reforming a raw material gas containing a hydrocarbon raw material into a reformed gas mainly composed of hydrogen gas (H ₂ );
A CO conversion device according to any one of claims 1 to 5 for transforming carbon monoxide (CO) remaining connected to the reformed gas to the reforming unit to the carbon dioxide (CO _2), and
An oxygen-containing gas supply means for supplying an oxygen-containing gas;
A reformed gas produced by the reforming means and subjected to a process for transforming CO by the CO converter, and a fuel cell for generating electricity using the oxygen-containing gas supplied by the oxygen-containing gas supply means;
An introduction gas supply means for introducing at least one of a reducing gas and an inert gas into the reforming means and the CO converter by the control device of the CO converter;
A fuel cell system comprising: Reforming means for reforming a raw material gas containing a hydrocarbon raw material into a reformed gas mainly composed of hydrogen gas (H ₂ );
A shift vessel connected to the reforming means and charged with a CO shift catalyst for converting carbon monoxide (CO) remaining in the reformed gas into carbon dioxide (CO ₂ ) so that the reformed gas can flow;
An oxygen-containing gas supply means for supplying an oxygen-containing gas;
An introduction gas supply means for introducing at least one of a reducing gas and an inert gas into the reforming means and the CO converter;
A control device for introducing at least one of the gases into the shift vessel by the introduction gas supply means at 50 ° C. or lower when the process of converting the CO by introducing the reformed gas into the shift vessel is started. When,
A fuel cell system comprising: The fuel cell system according to claim 7 or 8,
Comprising a raw material gas supply means for supplying the raw material gas produced by mixing the hydrocarbon raw material with water vapor to the reforming means,
The introduction gas supply means includes a gas obtained by gas-liquid separation of an effluent flowing from at least one of the reforming means, the CO conversion device, and the fuel cell. A fuel cell system comprising a circulation means for supplying gas. A raw material gas containing a hydrocarbon raw material is reformed into a reformed gas mainly composed of hydrogen gas (H ₂ ) by reforming means, and carbon monoxide (CO) remaining in the reformed gas is converted into a CO converter. An operation control method for a fuel cell system for controlling an operation state in a fuel cell system that generates electricity by being converted to carbon dioxide (CO ₂ ) after being converted to carbon dioxide (CO ₂ ) by a copper-based CO conversion catalyst charged in
When supplying the source gas and generating power in the fuel cell, at least one of a reducing gas and an inert gas is circulated through the CO conversion catalyst at 50 ° C. or lower. System operation control method. An operation control method for a fuel cell system according to claim 10,
The raw material gas is produced by mixing water vapor with the hydrocarbon raw material,
A cooling step in which when the power generation in the fuel cell is stopped, the supply of the hydrocarbon raw material is stopped and the steam is supplied to the reforming means and the CO conversion device to be cooled;
A method for controlling the operation of the fuel electric system, comprising: a purge step of stopping supply of the water vapor and supplying a purge gas to the reforming means and the CO conversion device after the cooling step.

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