JP2021050375A - Hydrogen purifier - Google Patents

Abstract

To provide a hydrogen purifier that can suppress deterioration of hydrogen purity of a purified hydrogen gas due to an increase of a contaminant permeation amount with deterioration of an electrochemical device.SOLUTION: A hydrogen purifier comprises: an electrochemical device 4 that dissociates hydrogen contained in a hydrogen-containing gas into a hydrogen ion and an electron at an anode 2 arranged on one principal surface of a polymer electrolyte 1 composed of polymer for selectively transporting the hydrogen ion, and that generates a purified hydrogen gas by combining the hydrogen ion and the electron which have been permeated through the polymer electrolyte 1 at a cathode 3 arranged on the other principal surface of the polymer electrolyte 1; a humidifier 7 that humidifies the hydrogen-containing gas to be supplied to the anode 2; and a controller 31 that increases the amount of humidify of the humidifier 7 as an operational time of the electrochemical device 4 gets longer. With these devices, the hydrogen purifier can suppress the deterioration of hydrogen purity of the purified hydrogen gas with the lapse of time.SELECTED DRAWING: Figure 1

Description

The present invention relates to a hydrogen purifier provided with an electrochemical device for producing a purified hydrogen gas having a higher hydrogen purity than the hydrogen-containing gas by utilizing an electrochemical reaction from the hydrogen-containing gas, and an operation method thereof.

Conventionally, some hydrogen purifiers of this type are equipped with an electrochemical device that uses an electrochemical reaction from a hydrogen-containing gas to generate a purified hydrogen gas having a higher hydrogen purity than the hydrogen-containing gas (for example). See Patent Document 1).

This electrochemical device has, for example, a configuration in which an electrolyte membrane-electrode assembly (MEA) in which an electrolyte membrane that selectively transports hydrogen ions is sandwiched between an anode and a cathode is sandwiched by a pair of separators.

Then, by supplying a hydrogen-containing gas to the anode and passing an electric current from the anode to the cathode through the electrolyte membrane, the oxidation reaction of (Chemical formula 1) occurs at the anode, and the reduction reaction of (Chemical formula 2) occurs at the cathode. Occurs.

以上の反応により、アノードに供給された水素含有ガスから、水素分子をカソードに移動させて、水素（精製水素ガス）を分離し、カソードから排出させることができる。このとき、電解質膜を構成する高分子膜のイオン透過性を高く維持するため、アノードには、加湿した水素含有ガスが供給される。

By the above reaction, hydrogen molecules can be moved to the cathode from the hydrogen-containing gas supplied to the anode, hydrogen (purified hydrogen gas) can be separated, and discharged from the cathode. At this time, in order to maintain high ion permeability of the polymer membrane constituting the electrolyte membrane, a humidified hydrogen-containing gas is supplied to the anode.

The hydrogen-containing gas supplied to the hydrogen purifier reforms hydrocarbon-based fuels (for example, city gas, liquefied petroleum gas, etc.) (for example, steam reforming) by a hydrogen generator having a fuel processor. It is produced by partial oxidation reforming). The hydrogen-containing gas produced here contains impurities such as carbon dioxide, methane, nitrogen, carbon monoxide, and water vapor.

The hydrogen-containing gas thus obtained is supplied to the anode of the electrochemical device, and by passing an electric current between the anode and the cathode, hydrogen is electrochemically separated (purified) from the hydrogen-containing gas. To generate purified hydrogen gas.

At this time, among the components contained in the hydrogen-containing gas of the anode, impurities such as carbon dioxide and methane, which have a higher partial pressure than the cascade, permeate the electrolyte membrane due to the difference in partial pressure, move to the cathode, and move from the cathode. It reduces the hydrogen purity of the discharged purified hydrogen gas.

At this time, it is generally practiced to maintain the hydrogen purity of the purified hydrogen gas sufficiently high by using an electrolyte membrane in which the permeation amount of impurities such as carbon dioxide and methane is suppressed to a low level.

Journal of Power Sources 132 (2004) 92-98 Lee at al.

However, in the conventional configuration, the deterioration of the electrolyte membrane progresses as the electrochemical device is used, the amount of impurity gas other than hydrogen moving from the anode to the cathode increases, and the hydrogen of the purified hydrogen gas discharged from the cathode increases. It had a problem that the purity was lowered.

The present invention solves the conventional problems, suppresses a decrease in hydrogen purity of purified hydrogen gas discharged from a cathode when using an electrochemical device, and stably purifies purified hydrogen having high hydrogen purity. It is an object of the present invention to provide a hydrogen purifier capable of purifying.

In order to solve the conventional problems, the hydrogen purifier of the present invention dissociates hydrogen contained in the hydrogen-containing gas into hydrogen ions and electrons at the anode arranged on one main surface of the electrolyte membrane, and dissociates hydrogen into hydrogen ions and electrons, and the other of the electrolyte membranes. It is a hydrogen purifier equipped with an electrochemical device that combines hydrogen ions and electrons that have passed through the electrolyte membrane at the cathode arranged on the main surface of the device to generate purified hydrogen gas, and the operating time of the electrochemical device is As the length increases, the concentration of at least one hydrogen or water vapor in the hydrogen-containing gas supplied to the anode increases.

As a result, the partial pressure of impurities other than water vapor in the hydrogen-containing gas supplied to the anode can be reduced, and the difference in partial pressure of impurities other than water vapor on both sides of the electrolyte membrane can be reduced. As a result, the increase in the amount of impurities permeating through the electrolyte membrane is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode over time is suppressed, and the purified hydrogen gas having a stable and high hydrogen purity is produced. Can be purified.

The hydrogen purifier of the present invention can suppress a decrease in hydrogen purity of purified hydrogen gas discharged from the cathode when using an electrochemical device over time, and can stably purify purified hydrogen having high hydrogen purity. It is possible to provide a highly reliable hydrogen purifier.

A block diagram showing a schematic configuration of a hydrogen purifier according to the first embodiment of the present invention. Characteristic diagram showing the change of hydrogen purity of purified hydrogen gas in the hydrogen purifier of Embodiment 1 of the present invention over time. A block diagram showing a schematic configuration of a hydrogen purifier according to a second embodiment of the present invention. Characteristic diagram showing the change of hydrogen purity of the purified hydrogen gas in the hydrogen purifier of the second embodiment of the present invention over time. A block diagram showing a schematic configuration of a hydrogen purifier according to a third embodiment of the present invention. Characteristic diagram showing the change of hydrogen purity of the purified hydrogen gas in the hydrogen purifier of the third embodiment of the present invention over time.

In the first invention, hydrogen contained in a hydrogen-containing gas is dissociated into hydrogen ions and electrons at an anode arranged on one main surface of the electrolyte membrane, and an electrolyte is provided at a cathode arranged on the other main surface of the electrolyte membrane. It is a hydrogen purifier equipped with an electrochemical device that combines hydrogen ions and electrons that have passed through the membrane to generate purified hydrogen gas. Hydrogen supplied to the anode as the operating time of the electrochemical device increases. It is configured to increase the concentration of at least one hydrogen or water vapor in the contained gas.

As a result, the partial pressure of impurities other than water vapor in the hydrogen-containing gas supplied to the anode can be reduced, and the difference in partial pressure of impurities other than water vapor on both sides of the electrolyte membrane can be reduced. As a result, the increase in the amount of impurities permeating through the electrolyte membrane is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode over time is suppressed, and purified hydrogen with high hydrogen purity is stably purified. can do.

The second invention, in particular, in the first invention, includes a humidifier that humidifies a hydrogen-containing gas, and a controller that increases the amount of humidification of the humidifier as the operating time of the electrochemical device increases. It is a thing.

As a result, the concentration of water vapor contained in the hydrogen-containing gas increases with time, and the difference in voltage division of impurities other than water vapor on both sides of the electrolyte membrane can be reduced. As a result, the increase in the amount of impurities permeating through the electrolyte membrane is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode over time is suppressed, and purified hydrogen with high hydrogen purity is stably purified. can do.

The third invention, in particular, in the first invention, increases the operating time of the bypass flow path communicating the anode and the cathode, the bypass flow rate adjusting valve arranged on the bypass flow path, and the electrochemical device. It is provided with a controller for adjusting the flow rate adjusting valve so that the flow rate of the purified hydrogen gas flowing from the cathode to the anode through the bypass flow path is increased.

As a result, the flow rate of the purified hydrogen gas with high hydrogen purity supplied from the cathode to the anode increases with time, and the concentration of hydrogen in the hydrogen-containing gas flowing in the anode increases, so that the water vapor on both sides of the electrolyte membrane increases. The expansion of the partial pressure difference of impurities other than the above can be suppressed. As a result, the increase in the amount of impurities permeating through the electrolyte membrane is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode over time is suppressed, and purified hydrogen with high hydrogen purity is stably purified. can do.

The fourth invention, in particular, in the first invention, is a hydrogen generator that steam-modifies a raw material containing a hydrocarbon to generate a hydrogen-containing gas, a raw material supply device that supplies the raw material to the hydrogen generator, and hydrogen. The raw material feeder so that the operating time of the water supply device that supplies water to the generator and the electrochemical device becomes longer, and the ratio of the water supplied to the hydrogen generator to the raw material supplied to the hydrogen generator becomes higher. And a controller that controls the supply amount of at least one of the water supply devices.

As a result, the water vapor concentration in the hydrogen-containing gas generated by the hydrogen generator increases with time, and the pressure difference between impurities other than water vapor on both sides of the electrolyte membrane can be reduced. As a result, the increase in the amount of impurities permeating through the electrolyte membrane is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode over time is suppressed, and purified hydrogen with high hydrogen purity is stably purified. can do.

Hereinafter, embodiments of the hydrogen purifier of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of a hydrogen purifier according to the first embodiment of the present invention. FIG. 2 is a characteristic diagram showing changes in hydrogen purity of purified hydrogen gas over time in the hydrogen purifier according to the first embodiment of the present invention.

As shown in FIG. 1, the hydrogen purifier 41 of the present embodiment includes an electrochemical device 4, a power source 5, a water remover 6, a humidifier 7, a hydrogen-containing gas flow path 10, and purified hydrogen gas. It includes a flow path 11, an anode off-gas flow path 12, and a controller 31.

Further, the electrochemical device 4 is composed of an electrolyte membrane 1, an anode 2, and a cathode 3.

The electrolyte membrane 1 is a polymer membrane that selectively transports hydrogen ions.

The anode 2 extracts electrons from hydrogen molecules (dissociates hydrogen contained in the hydrogen-containing gas into hydrogen ions and electrons) to generate hydrogen ions, and an anode electrode that supplies the hydrogen-containing gas to the anode electrodes. It is composed of a flow path.

The cathode 3 is composed of a cathode electrode that combines hydrogen ions and electrons to generate hydrogen molecules, and a cathode gas flow path that discharges purified hydrogen gas from the cathode electrode.

The electrochemical device 4 has a configuration in which an anode 2 is provided on one main surface of the electrolyte membrane 1 and a cathode 3 is provided on the other main surface.

The power supply 5 causes a current in a predetermined direction to flow between the anode 2 and the cathode 3 of the electrochemical device 4. Here, the current in the predetermined direction is a current flowing from the anode 2 to the cathode 3 through the electrolyte membrane 1.

The hydrogen-containing gas flow path 10 is a flow path for supplying the hydrogen-containing gas to the anode 2 from the external gas supply means 61.

The purified hydrogen gas flow path 11 is a flow path for supplying the purified hydrogen gas discharged from the cathode 3 to the hydrogen utilization device 51.

The anode off-gas flow path 12 is a flow path for discharging the hydrogen-containing gas discharged from the anode 2 to the outside of the hydrogen purifier 41.

The controller 31 controls the operation of the hydrogen purifier 41. The controller 31 includes a signal input / output unit (not shown), an arithmetic processing unit (not shown), and a storage unit (not shown) for storing a control program.

The hydrogen utilization device 51 is a tank for storing purified hydrogen gas supplied from the hydrogen purifier 41.

The gas supply means 61 is composed of a fuel processor that supplies hydrogen-containing gas generated from city gas by using a steam reforming reaction, and is connected to the anode 2 of the electrochemical device 4 by a hydrogen-containing gas flow path 10. There is.

The water remover 6 is a chiller installed in the purified hydrogen gas flow path 11 to remove water in the purified hydrogen gas discharged from the cathode 3.

The humidifier 7 is a bubbler type humidifier that is installed in the hydrogen-containing gas flow path 10 and humidifies the hydrogen-containing gas supplied from the gas supply means 61.

The operation and operation of the hydrogen purifier 41 of the present embodiment configured as described above will be described below. The following operation is performed by the controller 31 controlling the power supply 5, the water remover 6, and the humidifier 7 of the hydrogen purifier 41.

First, a hydrogen-containing gas having a carbon dioxide ratio of 20% and a hydrogen ratio of 80% is supplied from the gas supply means 61 to the humidifier 7 via the hydrogen-containing gas flow path 10. The numerical value of this ratio is a numerical value not considering the water vapor contained in the hydrogen-containing gas.

The humidifier 7 humidifies the hydrogen-containing gas so that the ratio of water vapor is 20%. Hydrogen-containing gas having a ratio of carbon dioxide humidified by the humidifier 7 of 16%, a ratio of hydrogen of 64%, and a ratio of water vapor of 20% is supplied to the anode 2 via the hydrogen-containing gas flow path 10. Will be done.

Next, the power source 5 causes a current of 200 amperes to flow between the anode 2 and the cathode 3 of the electrochemical device 4 through the electrolyte membrane 1. As a result, the electrochemical reaction proceeds in the electrochemical device 4, and purified hydrogen gas is generated from the hydrogen-containing gas at the cathode 3.

Here, the purified hydrogen gas contains steam having a saturated vapor pressure corresponding to the operating temperature of the electrochemical device 4. Here, the operating temperature is 60 ° C., and 20% of water vapor is contained. The water vapor contained in the purified hydrogen gas is completely removed by the water remover 6, and the purified hydrogen gas containing no water vapor is supplied to the hydrogen utilization device 51.

Here, a small amount of carbon dioxide moves from the anode 2 to the cathode 3 via the electrolyte membrane 1. As a result, purified hydrogen gas having a hydrogen purity of 99.97% containing a trace amount of carbon dioxide as a component other than hydrogen is supplied to the hydrogen utilization device 51 at a flow rate of 10 (L / min). Here, the impurity concentration of the purified hydrogen gas supplied to the hydrogen utilization device 51 is 0.03%.

Next, the humidifier 7 is increased with time by the controller 31, and the ratio of water vapor to the total hydrogen-containing gas is increased by 0.5% per 1000 hours of operation.

Here, the reason why the increase in the amount of humidification by the humidifier 7 by the controller 31 per 1000 hours of operation time is increased by 0.5% of the ratio of water vapor to the entire hydrogen-containing gas will be described.

The moving flow rate A (L / min) of carbon dioxide moving from the anode 2 to the cathode 3 through the electrolyte membrane 1 is proportional to the difference in the partial pressure of carbon dioxide between the anode 2 and the cathode 3, and is as shown in (Equation 1). Can be calculated.

ここで、Ｐ_Ａはアノード２における二酸化炭素の分圧（ｋＰａ）であり、Ｐ_Ｃはカソード３における二酸化炭素の分圧（ｋＰａ）である。

Here, _{P A} is the partial pressure of carbon dioxide in the anode 2 (kPa), the _{P C} is the partial pressure of carbon dioxide in the cathode 3 (kPa).

Further, K, which is a constant of proportionality, is 0.188 at the initial stage. The proportionality constant K increases with the operation time due to the deterioration of the electrolyte membrane 1. In the present embodiment, the proportionality constant K increases by 0.002 per 1000 hours of operation, and the flow rate A through which carbon dioxide moves increases.

Then, since the proportionality constant K becomes 0.388 after the operation time of 100,000 hours from the initial stage, the hydrogen purity of the purified hydrogen gas taken out from the cathode 3 and the water vapor removed by the water remover 6 is 99.94. It drops to%. The impurity concentration of the purified hydrogen gas at this time is 0.06%, which is twice the initial concentration.

Here, the amount of humidification by the humidifier 7 is increased, and the ratio of water vapor in the hydrogen-containing gas supplied from the humidifier 7 to the anode 2 via the hydrogen-containing gas flow path 10 is 0.5% per 1000 hours of operation time. increase. At this time, the proportion of carbon dioxide decreases by 0.1% per 1000 hours due to dilution due to the increase in water vapor.

As a result, the difference in carbon dioxide partial pressure between the anode 2 and the cathode 3 is reduced, and the amount of carbon dioxide transferred from the anode 2 to the cathode 3 is reduced.

At this time, the hydrogen purity of the purified hydrogen gas supplied to the hydrogen utilization device 51 changes as shown in FIG. 3, and the decrease in hydrogen purity can be suppressed.

As described above, the hydrogen purifier 41 of the present embodiment contains hydrogen contained in the hydrogen-containing gas at the anode 2 arranged on one main surface of the electrolyte membrane 1 made of a polymer that selectively transports hydrogen ions. Is dissociated into hydrogen ions and electrons, and the hydrogen ions and electrons that have passed through the electrolyte membrane 1 are combined at the cathode 3 arranged on the other main surface of the electrolyte membrane 1 to generate purified hydrogen gas. A hydrogen-containing gas flow path 10 that supplies hydrogen-containing gas to the anode 2 from an external gas supply means 61, and a purified hydrogen gas flow path 11 that supplies purified hydrogen gas discharged from the cathode 3 to the hydrogen utilization device 51. , The anode off-gas flow path 12 that discharges unused (surplus) hydrogen-containing gas from the anode 2 to the outside of the hydrogen purifier 41, and the anode 2 and cathode 3 of the electrochemical device 4 so that the electrochemical device 4 operates. A power source 5 for flowing a current in a predetermined direction between the two, a humidifier 7 provided in the middle of the hydrogen-containing gas flow path 10 for humidifying the hydrogen-containing gas supplied to the anode 2, and a purified hydrogen gas flow path 11. A water remover 6 provided on the way to remove water in the purified hydrogen gas discharged from the cathode 3, and a controller 31 for increasing the amount of humidification of the humidifier 7 as the operating time of the electrochemical device 4 becomes longer. , Is provided.

As a result, the ratio of carbon dioxide in the hydrogen-containing gas supplied to the anode 2 to the total hydrogen-containing gas decreases, and the difference in the partial pressure of carbon dioxide between the anode 2 and the cathode 3 decreases as the operating time increases. Become.

As a result, the increase in the amount of carbon dioxide moving from the anode 2 to the cathode 3 is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode 3 over time is suppressed, and the hydrogen purity is stably maintained. Highly purified hydrogen can be purified.

(Embodiment 2)
The hydrogen purifier according to the second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same components as those in the first embodiment may be designated by the same reference numerals and duplicate description may be omitted.

FIG. 3 is a block diagram showing a schematic configuration of the hydrogen purifier according to the second embodiment of the present invention. FIG. 4 is a characteristic diagram showing changes in hydrogen purity of purified hydrogen gas over time in the hydrogen purifier according to the second embodiment of the present invention.

The hydrogen purifier 42 of the present embodiment is different from the hydrogen purifier 41 of the first embodiment in that there is no humidifier 7 on the hydrogen-containing gas flow path 10, and the controller 32 is used instead of the controller 31. , The bypass flow path 13 and the bypass flow rate adjusting valve 8 are provided in the bypass flow path 13.

The controller 32 controls the operation of the hydrogen purifier 42. The controller 32 includes a signal input / output unit (not shown), an arithmetic processing unit (not shown), and a storage unit (not shown) for storing a control program.

The bypass flow path 13 is installed so that the cathode 3 and the anode 2 are communicated with each other and the purified hydrogen gas is refluxed from the cathode 3 to the anode 2.

The bypass flow rate adjusting valve 8 is a needle valve that adjusts the flow rate of purified hydrogen gas that is refluxed from the cathode 3 to the anode 2.

The operation and operation of the hydrogen purifier 42 of the present embodiment configured as described above will be described below. The following operation is performed by the controller 32 controlling the power supply 5, the water remover 6, and the bypass flow rate adjusting valve 8 of the hydrogen purifier 42.

First, a hydrogen-containing gas having a carbon dioxide ratio of 16%, a hydrogen ratio of 64%, and a water vapor ratio of 20% is supplied from the gas supply means 61 to the anode 2 via the hydrogen-containing gas flow path 10. To do.

Next, the power source 5 causes a current of 200 amperes to flow between the anode 2 and the cathode 3 of the electrochemical device 4 through the electrolyte membrane 1. As a result, the electrochemical reaction proceeds in the electrochemical device 4, and purified hydrogen gas is generated from the hydrogen-containing gas at the cathode 3.

Here, the purified hydrogen gas contains steam having a saturated vapor pressure corresponding to the operating temperature of the electrochemical device 4. Here, the operating temperature is 60 ° C., and the purified hydrogen gas contains 20% of water vapor. The water vapor contained in the purified hydrogen gas is completely removed by the water remover 6, and the purified hydrogen gas containing no water vapor is supplied to the hydrogen utilization device 51.

Here, a small amount of carbon dioxide moves from the anode 2 to the cathode 3 via the electrolyte membrane 1. As a result, purified hydrogen gas having a hydrogen purity of 99.97% containing a trace amount of carbon dioxide as a component other than hydrogen is supplied to the hydrogen utilization device 51 at a flow rate of 10 (L / min). Here, the impurity concentration of the purified hydrogen gas supplied to the hydrogen utilization device 51 is 0.03%.

Next, the bypass flow rate adjusting valve 8 is controlled by the controller 32, and the amount of purified hydrogen gas is refluxed from the cathode 3 to the anode 2. The flow rate to be refluxed is initially 0 (L / min), and is increased over time by 0.2 (L / min) per 1000 hours of operation.

Here, the reason for increasing the flow rate of the purified hydrogen gas refluxed from the cathode 3 to the anode 2 by 0.2 (L / min) per 1000 hours of operation time will be described.

The moving flow rate A (L / min) of carbon dioxide moving from the anode 2 to the cathode 3 through the electrolyte membrane 1 is proportional to the difference in the partial pressure of carbon dioxide between the anode 2 and the cathode 3, and is as shown in (Equation 1). Can be calculated.

The proportionality constant K is 0.188 at the initial stage, but increases with the operation time due to the deterioration of the electrolyte membrane 1. In the present embodiment, the proportionality constant K increases by 0.002 per 1000 hours of operation, and the flow rate A through which carbon dioxide moves increases.

After 100,000 hours of operation from the initial stage, the proportionality constant K becomes 0.388, and the hydrogen purity of the purified hydrogen gas taken out from the cathode 3 and from which water vapor has been removed by the water remover 6 is up to 99.94%. descend. The impurity concentration of the purified hydrogen gas at this time is 0.06%, which is twice the initial concentration.

Here, the flow rate of the purified hydrogen gas refluxed from the cathode 3 to the anode 2 via the bypass flow path 13 is increased by 0.2 (L / min) per 1000 hours of operation time.

At this time, the proportion of carbon dioxide decreases due to dilution due to the increase in hydrogen. As a result, the difference in carbon dioxide partial pressure between the anode 2 and the cathode 3 is reduced, and the amount of carbon dioxide transferred from the anode 2 to the cathode 3 is reduced.

At this time, the hydrogen purity of the purified hydrogen gas changes as shown in FIG. 4, and the decrease in hydrogen purity can be suppressed.

As described above, the hydrogen purifier 42 of the present embodiment contains hydrogen contained in the hydrogen-containing gas at the anode 2 arranged on one main surface of the electrolyte membrane 1 made of a polymer that selectively transports hydrogen ions. Is dissociated into hydrogen ions and electrons, and the hydrogen ions and electrons that have passed through the electrolyte membrane 1 are combined at the cathode 3 arranged on the other main surface of the electrolyte membrane 1 to generate purified hydrogen gas. A hydrogen-containing gas flow path 10 that supplies hydrogen-containing gas to the anode 2 from an external gas supply means 61, and a purified hydrogen gas flow path 11 that supplies purified hydrogen gas discharged from the cathode 3 to the hydrogen utilization device 51. , The anode off-gas flow path 12 that discharges unused (surplus) hydrogen-containing gas from the anode 2 to the outside of the hydrogen purifier 42, and the anode 2 and cathode 3 of the electrochemical device 4 so that the electrochemical device 4 operates. A power supply 5 that allows a current to flow in a predetermined direction between the two, a bypass flow path 13 that communicates the cathode 3 and the anode 2 to circulate purified hydrogen gas from the cathode 3 to the anode 2, and a bypass flow path 13 that circulates from the cathode 3 to the anode 2. The bypass flow control valve 8 provided in the middle of the bypass flow path 13 and the electrochemical device 4 can be operated for a long time, and the anode 3 can be used to adjust the flow rate of the purified hydrogen gas. It is provided with a controller 32 that adjusts the bypass flow rate adjusting valve 8 so that the flow rate of the purified hydrogen gas flowing to 2 is increased.

As a result, the ratio of carbon dioxide in the hydrogen-containing gas supplied to the anode 2 to the total hydrogen-containing gas decreases, and the difference in the partial pressure of carbon dioxide between the anode 2 and the cathode 3 decreases as the operating time increases. Become. As a result, the increase in the amount of carbon dioxide moving from the anode 2 to the cathode 3 is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode 3 over time is suppressed, and the hydrogen purity is stably maintained. Highly purified hydrogen can be purified.

(Embodiment 3)
The hydrogen purifier according to the third embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same components as those in the first embodiment may be designated by the same reference numerals and duplicate description may be omitted.

FIG. 5 is a block diagram showing a schematic configuration of a hydrogen purifier according to the third embodiment of the present invention. FIG. 6 is a characteristic diagram showing changes in hydrogen purity of purified hydrogen gas over time in the hydrogen purifier according to the third embodiment of the present invention.

The hydrogen purifier 43 of the present embodiment is different from the hydrogen purifier 41 of the first embodiment in that there is no humidifier 7 on the hydrogen-containing gas flow path 10, and the controller 33 is used instead of the controller 31. , The hydrogen generating device 62, the water supply device 14, and the raw material supply device 15 are provided.

The controller 33 controls the operation of the hydrogen purifier 43. The controller 33 includes a signal input / output unit (not shown), an arithmetic processing unit (not shown), and a storage unit (not shown) for storing a control program.

The hydrogen generation device 62 supplies a hydrogen-containing gas generated from methane by utilizing a steam reforming reaction, and is connected to the anode 2 of the electrochemical device 4 by a hydrogen-containing gas flow path 10.

The water supply device 14 is a water pump that supplies water necessary for the steam reforming reaction to the hydrogen generation device 62.

The raw material supply device 15 is a gas pump that supplies methane as a raw material to the hydrogen generation device 62.

The operation and operation of the hydrogen purifier 43 of the present embodiment configured as described above will be described below. The following operation is performed by the controller 33 controlling the power supply 5, the water remover 6, the water supply device 14, and the raw material supply device 15.

First, 12.7 (L / min) of water is supplied from the water supply device 14 to the hydrogen generation device 62, and 3.9 (L / min) of methane is supplied from the raw material supply device 15 to the hydrogen generation device 62.

At this time, in the hydrogen generation device 62, a hydrogen-containing gas having a carbon dioxide ratio of 16%, a hydrogen ratio of 64%, and a water vapor ratio of 20% is generated, and this hydrogen-containing gas is used as the hydrogen generation device 62. Is supplied to the anode 2 via the hydrogen-containing gas flow path 10.

Next, the power source 5 causes a current of 200 amperes to flow between the anode 2 and the cathode 3 of the electrochemical device 4 through the electrolyte membrane 1. As a result, the electrochemical reaction proceeds in the electrochemical device 4, and purified hydrogen gas is generated from the hydrogen-containing gas at the cathode 3.

Here, the purified hydrogen gas contains steam having a saturated vapor pressure corresponding to the operating temperature of the electrochemical device 4. Here, the operating temperature is 60 ° C., and 20% of water vapor is contained. The water vapor contained in the purified hydrogen gas is completely removed by the water remover 6, and the purified hydrogen gas containing no water vapor is supplied to the hydrogen utilization device 51.

Here, a small amount of carbon dioxide moves from the anode 2 to the cathode 3 via the electrolyte membrane 1. As a result, purified hydrogen gas having a hydrogen purity of 99.97% containing a trace amount of carbon dioxide as a component other than hydrogen is supplied to the hydrogen utilization device 51 at a flow rate of 10 (L / min). Here, the impurity concentration of the purified hydrogen gas supplied to the hydrogen utilization device 51 is 0.03%.

Next, the water supply device 14 is controlled by the controller 33, and the water supply amount is increased by 0.27 (L / min) over time per 1000 hours of operation time.

Here, the reason for increasing the water supply amount by 0.27 (L / min) per 1000 hours of operation time will be described.

The moving flow rate A (L / min) of carbon dioxide moving from the anode 2 to the cathode 3 through the electrolyte membrane 1 is proportional to the difference in the partial pressure of carbon dioxide between the anode 2 and the cathode 3, and is as shown in (Equation 1). Can be calculated. The proportionality constant K is 0.188 at the initial stage, but increases with the operation time due to the deterioration of the electrolyte membrane 1.
Further, K, which is a constant of proportionality, is 0.188 at the initial stage. The proportionality constant K increases with the operation time due to the deterioration of the electrolyte membrane 1. In the present embodiment, the proportionality constant K increases by 0.002 per 1000 hours of operation, and the flow rate A through which carbon dioxide moves increases.

Then, since the proportionality constant K becomes 0.388 after the operation time of 100,000 hours from the initial stage, the hydrogen purity of the purified hydrogen gas taken out from the cathode 3 and the water vapor removed by the water remover 6 is 99.94. It drops to%. The impurity concentration of the purified hydrogen gas at this time is 0.06%, which is twice the initial concentration.

Here, the amount of water supplied is increased over time by 0.27 (L / min) per 1000 hours of operation. At this time, the concentration of water vapor in the hydrogen-containing gas purified by the hydrogen generator 62 increases, which reduces the proportion of carbon dioxide. As a result, the difference in carbon dioxide partial pressure between the anode 2 and the cathode 3 is reduced, and the amount of carbon dioxide transferred from the anode 2 to the cathode 3 is reduced.

At this time, the hydrogen purity of the purified hydrogen gas changes as shown in FIG. 6, and the decrease in hydrogen purity can be suppressed.

As described above, the hydrogen purifier 43 of the present embodiment contains hydrogen contained in the hydrogen-containing gas at the anode 2 arranged on one main surface of the electrolyte membrane 1 made of a polymer that selectively transports hydrogen ions. Is dissociated into hydrogen ions and electrons, and hydrogen ions and electrons that have passed through the electrolyte membrane 1 are combined at the cathode 3 arranged on the other main surface of the electrolyte membrane 1 to generate purified hydrogen gas. A hydrogen generator 62 that generates a hydrogen-containing gas from methane using a steam reforming reaction, a raw material supply device 15 that supplies methane to the hydrogen generating device 62, and a hydrogen generating device 62 that are required for a steam reforming reaction. A water supply device 14 for supplying a large amount of water, a hydrogen-containing gas flow path 10 for supplying hydrogen-containing gas from a hydrogen generating device 62 to an anode 2, and a purified hydrogen gas discharged from a cathode 3 are supplied to a hydrogen utilization device 51. A purified hydrogen gas flow path 11, an anode off-gas flow path 12 that discharges unused (surplus) hydrogen-containing gas from the anode 2 to the outside of the hydrogen purifier 43, and an electrochemical device so that the electrochemical device 4 operates. Moisture removal for removing water in purified hydrogen gas provided in the middle of a purified hydrogen gas flow path 11 and a power source 5 for flowing a current in a predetermined direction between the anode 2 and the cathode 3 of 4 and removing water in the purified hydrogen gas discharged from the cathode 3. A device 6 and a controller 33 for increasing the amount of water supplied to the water supply device 14 so that the operating time of the electrochemical device 4 becomes longer and the S / C (steam / carbon) ratio becomes higher are provided. It is a thing.

As a result, the ratio of carbon dioxide in the hydrogen-containing gas supplied to the anode 2 to the total hydrogen-containing gas decreases, and the difference in the partial pressure of carbon dioxide between the anode 2 and the cathode 3 decreases as the operating time increases. Become. As a result, the increase in the amount of carbon dioxide moving from the anode 2 to the cathode 3 is suppressed, so that the decrease in hydrogen purity of the purified hydrogen gas discharged from the cathode 3 over time is suppressed, and the hydrogen purity is stably maintained. Highly purified hydrogen can be purified.

As described above, the hydrogen purifier according to the present invention can suppress a decrease in hydrogen purity of purified hydrogen gas over time and can stably purify purified hydrogen having high hydrogen purity. Therefore, a fuel cell system. It can also be applied to applications such as hydrogen utilization systems such as hydrogen stations and hydrogen stations that generally supply hydrogen.

1 Electrolyte membrane 2 Anode 3 Cathode 4 Electrochemical device 5 Power supply 6 Moisture remover 7 Humidifier 8 Bypass flow control valve 10 Hydrogen-containing gas flow path 11 Purified hydrogen gas flow path 12 Anode off gas flow path 13 Bypass flow path 14 Water supply device 15 Raw material feeder 31 Controller 32 Controller 33 Controller 41 Hydrogen purifier 42 Hydrogen purifier 43 Hydrogen purifier 51 Hydrogen utilization equipment 61 Gas supply means 62 Hydrogen generator

Claims (4)

Hydrogen contained in the hydrogen-containing gas was dissociated into hydrogen ions and electrons at the anode arranged on one main surface of the electrolyte membrane, and permeated through the electrolyte membrane at the cathode arranged on the other main surface of the electrolyte membrane. A hydrogen purifier equipped with an electrochemical device that combines the hydrogen ions and the electrons to generate purified hydrogen gas.
A hydrogen purifier characterized in that the operating time of the electrochemical device is increased and the concentration of at least one hydrogen or water vapor in the hydrogen-containing gas supplied to the anode is increased. A humidifier that humidifies the hydrogen-containing gas and
A controller that increases the amount of humidification of the humidifier as the operating time of the electrochemical device increases.
The hydrogen purifier according to claim 1, wherein the hydrogen purifier is provided. A bypass flow path communicating the anode and the cathode,
A bypass flow rate adjusting valve arranged on the bypass flow path and
A controller that adjusts the flow rate adjusting valve so that the flow rate of the purified hydrogen gas flowing from the cathode through the bypass flow path to the anode increases as the operating time of the electrochemical device increases.
The hydrogen purifier according to claim 1, wherein the hydrogen purifier is provided. A hydrogen generator that steam reforms a raw material containing hydrocarbons to generate the hydrogen-containing gas,
A raw material supply device that supplies the raw material to the hydrogen generator, and
A water supply device that supplies the water to the hydrogen generator,
Of the raw material supply device and the water supply device, the ratio of the water supplied to the hydrogen generating device to the raw material supplied to the hydrogen generating device becomes high as the operating time of the electrochemical device becomes long. A controller that controls at least one supply,
The hydrogen purifier according to claim 1, wherein the hydrogen purifier is provided.

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