WO2013046958A1

WO2013046958A1 - Hydrogen production system

Info

Publication number: WO2013046958A1
Application number: PCT/JP2012/070467
Authority: WO
Inventors: 寛人内藤
Original assignee: 株式会社日立製作所
Priority date: 2011-09-30
Filing date: 2012-08-10
Publication date: 2013-04-04
Also published as: JPWO2013046958A1; JP5837081B2

Abstract

The present invention provides a hydrogen production system which is capable of suppressing the occurrence of a reverse reaction in a hydrogen producing device when electrolysis stops due to switching of the connection configuration of the hydrogen producing device based on fluctuations in renewable energy. The hydrogen production system (100) of the present invention includes a generator (1) which switches from renewable energy to electric energy, a plurality of hydrogen producing devices (2a-2n) connected in series or in parallel for producing hydrogen gas using electric energy obtained from the generator (1), and switching elements (4-6) for switching the connection configuration of the plurality of hydrogen producing devices (2a-2n). The hydrogen production system also includes a voltage applying means (3a-3n, 7) for applying voltage and a control device (8) for controlling the switching elements (4-6) and voltage applying means (3a-3n, 7) when production of hydrogen gas stops in one of the hydrogen producing devices (2a-2n) due to switching of the connection configuration by the switching elements (4-6).

Description

Hydrogen production system

The present invention relates to a hydrogen production system that produces hydrogen using electric power with output fluctuations such as generated power derived from renewable energy, and more particularly to a hydrogen production system using electrolysis.

Mass consumption of fossil fuels continues, for example, global warming due to carbon dioxide, air pollution in urban areas, etc. are becoming serious. Under such circumstances, hydrogen is attracting attention as an energy source for the next generation to replace fossil fuels. Hydrogen can be produced by electrolysis using renewable energy typified by solar cells, wind power, and the like, and further, only water is generated by combustion. Therefore, hydrogen is a clean energy source that emits less environmental pollutants during production and use.

As a method for producing hydrogen, steam reforming of fossil fuel is widely used industrially. In addition to this, many production methods are known for hydrogen, such as by-product hydrogen associated with the production of iron or soda and hydrogen generated by reactions using thermal decomposition, photocatalysts, microorganisms, and water electrolysis. It has been. Especially, as electric power required for electrolysis of water, it is possible to use electric power from various supply sources. Therefore, the method for producing hydrogen by electrolysis of water is regarded as important as a method for producing an energy source independent of a specific region.

However, in order to construct a hydrogen production system using renewable energy, it is necessary to consider the amount of electric power (that is, the amount of power generation) generated by the renewable energy. That is, the amount of power generated by renewable energy usually varies depending on weather conditions. For example, in the case of wind power generation using wind power as renewable energy, the amount of power generation varies depending on the strength of the wind, and in the case of solar power generation using sunlight, the intensity of sunlight and the duration of sunlight.

In order to cope with such a change in electric energy, for example, Patent Document 1 includes a plurality of cell stacks including a plurality of water electrolysis cells, and the cell stacks are electrically connected to each other in series or in parallel. A water electrolyzer, power supply means for supplying power to the water electrolyzer, a voltage control unit that variably controls the voltage of power supplied to the water electrolyzer, and power supplied to the water electrolyzer Accordingly, an energy-efficient hydrogen production facility using a generator as a power source is described by including a stack number control unit that selects a cell stack usage number accordingly.

JP 2005-126792 A

In order to respond to changes in the amount of power generation, it is effective to adjust the electrical connection configuration and supply power of the water electrolysis system according to the fluctuating power of renewable energy, as in Patent Document 1 and the like. On the other hand, in the water electrolysis apparatus, when power supply is stopped, a power generation reaction opposite to the electrolysis reaction proceeds due to the produced residual gas and the electric charge stored in the electric double layer. In the water electrolysis apparatus, there is a problem that electrode degradation is likely to occur by repeatedly performing an electrolysis reaction and a power generation reaction by supplying and shutting off electric power. In addition, there is a problem that the gas in the pipe that discharges the gas produced by the water electrolysis apparatus flows backward due to the consumption of the gas produced by electrolysis as the power generation reaction proceeds. On the other hand, although it is possible to provide a check valve for preventing a backflow in the pipe, the gas inside the water electrolysis device is consumed, thereby causing an internal gas pressure imbalance.

Thus, problems such as electrode deterioration and internal gas pressure imbalance due to the reverse reaction of the water electrolysis device occur only by supplying or shutting off power to the water electrolysis system.

The present invention has been made to solve the above-mentioned problems, and its purpose is the reverse of the water electrolysis apparatus resulting from the switching of the electrical connection configuration of the water electrolysis apparatus in accordance with fluctuations in the supplied power. An object of the present invention is to provide a hydrogen production system capable of suppressing the occurrence of reaction.

As a result of intensive investigations to solve the above problems, the present inventors have found that by stopping the electrolysis in a state where a voltage is applied to the water electrolysis device, it is possible to suppress the progress of the reverse reaction that occurs when the electrolysis is stopped. The headline, the present invention has been reached.

A hydrogen production system according to the present invention includes a plurality of hydrogen production apparatuses that are connected in series or in parallel to produce hydrogen gas using DC power, a plurality of switching elements that switch connection configurations of the plurality of hydrogen production apparatuses, Of the hydrogen production apparatus, voltage application means for applying a voltage, and the switching element and the voltage application means are controlled for the hydrogen production apparatus that stops production of hydrogen gas by switching the connection configuration by the switching element. And a control device.

The hydrogen production system of the present invention can suppress the occurrence of a reverse reaction of the water electrolysis apparatus due to the switching of the electrical connection configuration of the water electrolysis apparatus according to the fluctuation of the supplied power.

It is a mimetic diagram of the composition of the hydrogen production system by a 1st embodiment of the present invention. It is a figure explaining operation | movement of the hydrogen production system by 1st Embodiment of this invention. 1 is a schematic diagram of a circuit configuration of a hydrogen production system according to a first embodiment of the present invention. It is a schematic diagram of a structure of the hydrogen production system by 2nd Embodiment of this invention. It is a schematic diagram of a structure of the hydrogen production system by 3rd Embodiment of this invention. It is a figure explaining operation | movement of the hydrogen production system by 3rd Embodiment of this invention. It is a schematic diagram of the circuit structure of the hydrogen production system by 3rd Embodiment of this invention. It is a schematic diagram of a structure of the hydrogen production system by 4th Embodiment of this invention. It is a schematic diagram of a structure of the hydrogen production system by 5th Embodiment of this invention. It is a figure which shows the voltage-current characteristic in the electrolysis of a water electrolysis apparatus.

Hereinafter, a hydrogen production system according to an embodiment of the present invention will be described with reference to the drawings as appropriate.

FIG. 10 shows voltage-current characteristics in a water electrolysis device (water electrolysis device). By applying a voltage obtained by adding an overvoltage and a liquid electric resistance to the theoretical electrolysis voltage between the electrodes, current starts to flow, electrolysis proceeds, and hydrogen is generated. When the power supply to the water electrolysis device is stopped, the voltage decreases and the electrolysis stops. At this time, in the electrolysis apparatus, there are gas generated by electrolysis and electric charge stored in the electric double layer. The gas generated by this electrolysis reacts with the electric charge, so that the electrode potential becomes lower than the theoretical electrolysis voltage and shifts to a power generation reaction. In order to suppress the occurrence of a reverse reaction (power generation reaction) when the electrolysis of the water electrolysis apparatus is stopped, the present inventors have intensively studied. As a result, the electrolysis reaction does not proceed with respect to the water electrolysis apparatus. It has been found that the occurrence of a reverse reaction can be suppressed by applying a voltage.

The present invention relates to a water electrolysis apparatus that stops electrolysis in a hydrogen production system that produces hydrogen using a water electrolysis apparatus using electric power whose output fluctuates, such as a power generation apparatus that converts renewable energy into electric energy. Further, a voltage applying means for applying a voltage is provided.

Examples of the voltage applying means include means for applying a voltage to the water electrolysis apparatus by an external power source, and means for applying a voltage to the water electrolysis apparatus by switching the circuit configuration when stopping the electrolysis of the water electrolysis apparatus. .

Hereinafter, embodiments of the hydrogen production system of the present invention will be described using specific examples.
[First Embodiment]
FIG. 1 is a diagram schematically showing the configuration of the hydrogen production system according to the first embodiment of the present invention. In FIG. 1, a thick solid line represents an electrical wiring, and a thin solid line represents a signal line (for example, a control signal, a measurement signal, etc.). These lines are wirings for connecting the means to each other and represent transmission / reception of signals.

As shown in FIG. 1, the hydrogen production system 100 according to the first embodiment produces hydrogen gas from renewable energy. The hydrogen production system 100 includes a renewable energy power generation device 1, a hydrogen production device 2 (2a to 2n) as a hydrogen production means, and a protection device 3 (3a to 3n) that prevents a chemical reaction of the hydrogen production device 2. And switching elements 4 to 6 for adjusting the connection configuration of the hydrogen production apparatus 2 and a switching element 7 for adjusting the connection of the protection apparatus 3. In this system, the protection device 3 and the switching element 7 serve as voltage application means for applying a voltage to the hydrogen production device 2 (water electrolysis device) that stops electrolysis.

Renewable energy represents, for example, renewable energy such as sunlight, wind power, geothermal power, and hydropower. In addition, the renewable energy is not transported to the renewable energy power generation apparatus 1 through electrical or physical connection lines, piping, or the like, and is based on global weather conditions. Specifically, when the renewable energy is, for example, sunlight, the renewable energy power generation apparatus 1 described later is, for example, a solar cell, a solar power generation system, or the like.

Renewable energy power generation device 1 (hereinafter, also simply referred to as “power generation device 1”) converts renewable energy such as sunlight and wind power into electric power. The power generation device 1 is electrically connected to the hydrogen production device 2 so that the power generated by the power generation device 1 can be supplied to the hydrogen production device 2.

The hydrogen production device 2 (water electrolysis device) produces hydrogen using the electric power obtained by the power generation device 1. Specifically, the hydrogen production apparatus 2 generates hydrogen gas by electrolyzing water (or an aqueous solution) using supplied DC power. Therefore, the more electric power is supplied from the power generation device 1 to the hydrogen production device 2, the more hydrogen is produced (generated) in the hydrogen production device 2. The hydrogen production device 2 is electrically connected to the power generation device 1. Here, there are cases where the electric power obtained depending on the type of regenerative energy is DC power or AC power. When the obtained power is AC power, the DC power is supplied to the hydrogen production apparatus 2 after being converted into DC power by a rectifier.

Although the specific configuration of the hydrogen production apparatus 2 is not particularly limited, the hydrogen production apparatus 2 supplies, for example, water, an electrolyte, an electrode catalyst for promoting a reaction provided so as to sandwich the electrolyte, and external power. An electrolysis cell holding a current collector or the like is provided. Then, water is electrolyzed by this electrode catalyst, and hydrogen and oxygen are generated. In the present invention, an electrolysis cell or an electrolysis stack in which electrolysis cells are laminated in multiple layers is defined as a hydrogen production apparatus 2.

The electrolyte is not particularly limited as long as at least hydrogen is generated by electrolysis, but a compound that exhibits alkalinity when dissolved in water, such as potassium hydroxide, is preferable. By using such a compound, the hydrogen production apparatus 2 that is inexpensive and hardly corrodes can be obtained. Further, as the electrolyte, for example, a solid polymer electrolyte such as Nafion (registered trademark) can be used.

Water electrolysis conditions are not particularly limited, and can be set arbitrarily as long as at least hydrogen can be generated.

The protection device 3 has an external power source, and is a device that operates to prevent or suppress the reverse reaction of the hydrogen production device 2 at the same time as the supply of generated power derived from renewable energy is shut off. As a specific example, the protection device 3 includes a voltage application mechanism that sweeps an external power source in parallel to each hydrogen production device 2, and when power supply to the hydrogen production device 2 is stopped, a voltage is supplied from the external power source. Examples of the protective mechanism to be applied include. At this time, current is not necessarily required.

The switching elements 4 to 6 are switching elements that have a function of supplying the electric power generated by the power generation apparatus 1 to the hydrogen production apparatus 2 or cutting it off from the hydrogen production apparatus 2 and can control the driving state by an external signal. Examples of the switching element include a relay element and a semiconductor element.

The switching element 7 has a function of energizing or shutting off the external power source of the protection device 3 from the hydrogen production device 2 when the supply of generated power derived from renewable energy to the hydrogen production device 2 is interrupted. In addition, the switching element can control the driving state by an external signal. Examples of the switching element include a relay element and a semiconductor element. At this time, the external signal for the switching element 7 can be applied by sharing the external signal for the switching elements 4 to 6.

The control device 8 includes a signal processing unit, and controls the switching elements 4 to 7 based on the device configuration determined by the signal processing unit according to the amount of power generated by the renewable energy power generation device 1 and the electrical characteristics of the hydrogen production device 2. Any device that transmits an energization signal or a cut-off signal is not particularly limited. The control device 8 controls the protection devices 3 and the switching devices 7 which are voltage application means by controlling the switching devices 4 to 7.
<Operation>
Next, the operation of each component of the hydrogen production system 100 of the present embodiment when producing hydrogen gas will be described with reference to FIG.

First, for example, using a renewable energy such as sunlight, the power generation device 1 (for example, a solar cell) generates electric power. The generated electric power is supplied to the hydrogen production apparatus 2.

The electrical connection configuration of the serial number and / or the parallel number of the hydrogen production apparatus 2 is determined and switched by the signal processing unit of the control device 8 according to the generated power and the electrical characteristics of the hydrogen production apparatus 2. While the electrical connection configuration is switched, the hydrogen production apparatus 2 starts electrolysis of water according to the supplied generated power and generates hydrogen. Here, the control device 8 and the switching elements 4 to 6 are switched to the connection mode of the water electrolysis means for obtaining the maximum hydrogen gas amount.

When the generated power is reduced due to fluctuations in renewable energy, it is necessary to reduce the number of connections of the hydrogen production apparatus 2. When stopping the hydrogen production apparatus 2 in operation, the protection apparatus 3 is operated by an external power source in order to suppress and prevent a chemical reaction using the remaining gas. The voltage value of the external power supply may be such that the electric double layer formed inside the hydrogen production apparatus 2 is maintained, and can be swept to such an extent that no current flows inside the hydrogen production apparatus 2. For example, it may be the Eeq point in the voltage-current characteristic of the hydrogen production apparatus 2 shown in FIG. 10, or may be a voltage value within the range indicated by ΔE.

The environment in which the series of operations is performed is not particularly limited, and can be performed in any environment as long as the above-described problem can be solved. In addition, it is not always necessary to install all the components in the same place. For example, the hydrogen production apparatus 2 is installed indoors, and the hydrogenation apparatus 10 (not shown in FIG. 1 and described later) is installed outdoors. Can be installed arbitrarily.
<Operation control of protection device 3 by external power source>
Next, operation control of the protection device 3 will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram showing an ON-OFF time chart of the switching elements 4 to 6 in the hydrogen production system 100 according to the first embodiment of the present invention. FIG. 3 is an electrical equivalent circuit diagram of the hydrogen production system 100 at the timings (1) to (4) described in FIG. In FIG. 3, the input voltage derived from renewable energy is V0, the resistances of the equivalent circuits of the

hydrogen production apparatuses

2a, 2b, and 2c are R2a, R2b, and R2c, respectively, and the currents flowing through the hydrogen production apparatuses are I2a, I2b, and I2c. The external power supply voltage was defined as Eeq. In FIGS. 2 and 3, only three apparatuses, hydrogen production apparatuses 2a to 2c, are shown for simplification, but the number of hydrogen production apparatuses is not limited.

As shown in FIG. 2, first, in a state where the electric power derived from the renewable energy power generation device 1 is not input to the hydrogen production system 100, the external power source of the protection device 3 is swept to all the hydrogen production devices. While S401 to S403 are in the ON state, S101 to S103, S201 to S203, and S301 to S303 are in the OFF state.

At this time, when electric power derived from renewable energy is input to the hydrogen production system 100, the configuration of the hydrogen production apparatus is determined according to the amount of electric power. In FIG. 2, (1) assumes a parallel configuration of two

hydrogen production apparatuses

2a and 2b, and S101, S102, S201, and S202 are switched to the ON state, and S401 and S402 are switched to the OFF state. This is shown in an electrical equivalent circuit diagram as shown in FIG. Current flows into the

hydrogen production apparatuses

2a and 2b by electric power derived from renewable energy (voltage is V0), and hydrogen gas is generated. On the other hand, in the hydrogen production device 2c being stopped, the external protection device 3 (3c) is driven by an external power source, and a voltage value in a range in which no current flows is swept so that gas flows into the hydrogen production device 2c, hydrogen The reverse reaction in the production apparatus 2c is prevented.

Next, (2) in FIG. 2 assumes a configuration of only one device of the hydrogen production device 2b, and S401 is switched to an ON state and S101 and S201 are switched to an OFF state as compared with (1). This is shown in an electrical equivalent circuit diagram as shown in FIG. Compared with FIG. 3 (1), the hydrogen production apparatus 2a stops, the electric power derived from renewable energy is applied only to the hydrogen production apparatus 2b, and hydrogen gas is produced only by the hydrogen production apparatus 2b. On the other hand, in the

hydrogen production apparatuses

2a and 2c that have stopped, the external protection device 3 (3a, 3c) is driven by an external power source, and the voltage value in a range in which no current flows is swept. Gas inflow and reverse reaction in the

hydrogen production apparatuses

2a and 2c are prevented.

Next, (3) in FIG. 2 assumes a serial configuration of two

hydrogen production apparatuses

2b and 2c. Compared with (2), S203 and S302 are in the ON state, and S202 and S403 are in the OFF state. Switch to. This is shown in an electrical equivalent circuit diagram as shown in FIG. Current flows into the

hydrogen production apparatuses

2b and 2c by the electric power derived from renewable energy (voltage is V0), and hydrogen gas is generated. On the other hand, in the hydrogen production apparatus 2a being stopped, the external protection device 3 (3a) is driven by an external power source, and a voltage value in a range in which no current flows is swept, so that gas flows into the hydrogen production apparatus 2a, hydrogen The reverse reaction in the production apparatus 2a is prevented.

Finally, (4) in FIG. 2 assumes the configuration of only one hydrogen production apparatus 2c. Compared with (3), S103 and S402 are turned off, and S102 and S302 are turned off. Change. This is shown in an electrical equivalent circuit diagram as shown in FIG. Compared with FIG. 3 (3), the hydrogen production apparatus 2b is stopped, the electric power derived from renewable energy is applied only to the hydrogen production apparatus 2c, and hydrogen gas is produced only by the hydrogen production apparatus 2c. On the other hand, the

hydrogen production apparatuses

2a and 2b that are stopped are driven by the external protection device 3 (3a, 3b) by an external power source, and the voltage value in a range in which no current flows is swept. Gas inflow and reverse reaction in the

hydrogen production apparatuses

2a and 2b are prevented.
<Summary>
As described above, according to the hydrogen production system 100 according to the first embodiment, hydrogen gas can be dealt with fluctuations in the supply amount of renewable energy, the deterioration of the hydrogen production apparatus can be suppressed, and renewable energy can be used without waste. Can be manufactured.
[Second Embodiment]
Next, a hydrogen production system 200 according to the second embodiment will be described with reference to FIG. 4 that are denoted by the same reference numerals as those in FIG. 1 represent the same components, and a detailed description thereof will be omitted.

In the hydrogen production system 200 of the present embodiment, one protection device 3 is connected to each hydrogen production device.

In FIG. 4, the control device 8 determines whether the switching element 7 is opened or closed based on the control signal transmitted to the switching element 4 and the switching element 6, and transmits the control signal to the switching element 7. When a voltage is applied from the protection device 3 when the hydrogen production apparatus 2 is stopped, electrode deterioration of the hydrogen production apparatus 2 is suppressed. Subsequent operations are the same as those in FIG. 1, and a detailed description thereof will be omitted.

In this way, the hydrogen production system 200 according to the second embodiment also copes with fluctuations in the supply amount of renewable energy, suppresses deterioration of the hydrogen production apparatus, and uses hydrogen gas without waste using renewable energy. Can be manufactured.
[Third Embodiment]
Next, a hydrogen production system 300 according to the third embodiment will be described with reference to FIG. In FIG. 5, the same reference numerals as those in FIG. 1 denote the same components, and detailed description thereof is omitted.

In the hydrogen production system 300 of this embodiment, the switching element 4 and the switching element 7 are removed from the configuration with respect to FIG. 1, and the protection devices 3 (3a to 3n) are electrically connected in series with the hydrogen production apparatus. It is a configuration.

The protection device 3 (3a to 3n) in FIG. 5 is configured to be electrically connected in series to the hydrogen production device 2 (2a to 2n), for example, a variable resistor. For example, consider a case where a configuration in which four hydrogen production apparatuses are connected in parallel is switched to a parallel connection of three apparatuses, that is, one apparatus is stopped. At that time, if a resistance higher than the internal resistance of the conventional hydrogen production device is inserted in series and connected to the hydrogen production device to be stopped, current is divided into the other three hydrogen production devices according to the diversion rule. Is done. On the other hand, since the hydrogen production apparatus in which the series resistor is inserted is electrically connected in parallel, the voltage of the renewable energy power generation is swept, and the chemical reaction can be prevented or suppressed. That is, by adjusting the resistance value inserted and connected, only the voltage can be applied to the hydrogen production apparatus to be stopped.

<Operation control of protection device 3>
Next, operation control of the protection device 3 will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram showing an ON-OFF time chart of the switching elements 5 and 6 in the hydrogen production system 300 according to the third embodiment of the present invention. FIG. 7 is an electrical equivalent circuit diagram of the hydrogen production system 300 at the timings (1) to (4) described in FIG. In FIG. 7, the input voltage derived from renewable energy is V0, the resistances of the equivalent circuits of the

hydrogen production apparatuses

2a, 2b, and 2c are R2a, R2b, and R2c, respectively, and the currents flowing through the hydrogen production apparatuses are I2a, I2b, and I2c. The voltages applied to each hydrogen production apparatus were defined as V2a, V2b, and V2c. Further, the variable resistance type protection devices 3 (3a to 3c) electrically connected in series to the hydrogen production device were defined as R3a, R3b, and R3c, respectively, and applied voltages were defined as V3a, V3b, and V3c. In FIGS. 6 and 7, only three apparatuses, hydrogen production apparatuses 2a to 2c, are shown for simplification, but the number of hydrogen production apparatuses is not limited.

As shown in FIG. 6, first, in a state where the electric power derived from the renewable energy power generation apparatus 1 is not input to the hydrogen production system 300, the variable resistance type protection devices 3 (3a to 3c) connected in series to all the hydrogen production apparatuses This shows a resistance value close to infinity, so that no current flows through each hydrogen production apparatus. At this time, S201 to S203 are in the ON state, while S301 to S303 are in the OFF state.

At this time, when electric power derived from renewable energy is input to the hydrogen production system 300, the configuration of the hydrogen production apparatus is determined according to the amount of electric power. In FIG. 6 (1), a parallel configuration of two

hydrogen production apparatuses

2a and 2b is assumed, and there is no change in the ON / OFF of the switching element in the case of parallel driving. However, when the parallel connection type drive is determined, the

protection devices

3a and 3b are controlled so that the resistance value takes a value close to zero, and the protection device 3c has (a) a current I2c flowing through the hydrogen production device 2c. The resistance value R3c of the protection device 3c is controlled so that the numerical value is as close to zero as possible and (b) V2c = V0 × R2c / (R2c + R3c) is within the range of Eeq or ΔE. This is shown in an electrical equivalent circuit diagram as shown in FIG. 7 (1). Current flows into the

hydrogen production apparatuses

2a and 2b by electric power (voltage is V0) derived from renewable energy, and hydrogen gas is generated. On the other hand, in the hydrogen production apparatus 2c being stopped, the protective device 3c having the resistance value R3c that satisfies the conditions (a) and (b) described above causes the voltage value in a range in which no current flows to be swept, so that the hydrogen production apparatus 2c Prevents gas inflow and reverse reaction.

Next, (2) in FIG. 6 assumes the configuration of only one device of the hydrogen production device 2b, and at this time, there is no change in ON / OFF of the switching element as compared with (1). However, when the configuration of only one device is determined, the protection device 3b is controlled so that the resistance value R3b takes a value close to zero, and the

protection devices

3a and 3c have the resistance values R3a and R3c as (a) a hydrogen production device. The currents I2a and I2c flowing through 2a and 2c are infinitely close to zero, and (b) V2a = V0 × R2a / (R2a + R3a) and V2c = V0 × R2c / (R2c + R3c) are in the range of Eeq or ΔE Control to be inside. This is shown in an electrical equivalent circuit diagram as shown in FIG. In the electrical equivalent circuit diagram of FIG. 7 (2), compared with FIG. 7 (1), the hydrogen production apparatus 2a is stopped, and electric power derived from renewable energy is applied only to the hydrogen production apparatus 2b to produce hydrogen gas. Is done. On the other hand, in the

hydrogen production apparatuses

2a and 2c that have been stopped, voltage values in a range in which no current flows are swept by the

protection apparatuses

3a and 3c having the resistance values R3a and R3c that satisfy the above conditions (a) and (b). Thus, gas inflow and reverse reaction to the

hydrogen production apparatuses

2a and 2c are prevented.

Next, (3) in FIG. 6 assumes a serial configuration of two apparatuses,

hydrogen production apparatuses

2b and 2c, and S302 is switched to an ON state and S202 is switched to an OFF state as compared with (2). At the same time, the protection device 3b is controlled so that the resistance value R3b takes a value close to zero, and the protection device 3c is controlled to take a resistance value R3c that is almost infinite, so that the current I2c is reduced to zero. Set to a value close to. Further, the protection device 3a has a resistance value R3a such that (a) the current I2a flowing through the hydrogen production device 2a is a value close to zero, and (b) V2a = V0 × R2a / (R2a + R3a) is Eeq or ΔE. Control to be within the range. This is shown in an electrical equivalent circuit diagram as shown in FIG. Current flows into the

hydrogen production apparatuses

2b and 2c by the electric power derived from renewable energy (voltage is V0), and hydrogen gas is generated. On the other hand, the hydrogen production apparatus 2a in a stopped state is a range in which no current flows by the

protection devices

3a and 3c having the resistance value R3a that satisfies the above conditions (a) and (b) and the resistance value R3c that is close to infinity, respectively. Is swept away to prevent gas inflow and reverse reaction to the hydrogen production apparatus 2a.

Finally, (4) in FIG. 6 assumes the configuration of only one device of the hydrogen production device 2c. Compared with (3), S202 is switched to the ON state and S302 is switched to the OFF state. At the same time, the protection device 3c is controlled so that the resistance value R3c takes a value close to zero, and the

protection devices

3a and 3b are controlled so that the resistance values R3a and R3b are (a) currents I2a and I2b flowing through the

hydrogen production devices

2a and 2b. (B) V2a = V0 × R2a / (R2a + R3a) and V2b = V0 × R2b / (R2b + R3b) are controlled to be within the range of Eeq or ΔE. This is shown in an electrical equivalent circuit diagram as shown in FIG. 7 (4) (same view as FIG. 7 (2)). In the electrical equivalent circuit diagram of FIG. 7 (4), compared with FIG. 7 (3), the hydrogen production apparatus 2b is stopped, and the renewable energy-derived power is applied only to the hydrogen production apparatus 2c to produce hydrogen gas. The On the other hand, in the

hydrogen production apparatuses

2a and 2b that have stopped, the voltage values in a range in which no current flows are swept by the

protection apparatuses

3a and 3b having the resistance values R3a and R3b that satisfy the above conditions (a) and (b). Thus, gas inflow and reverse reaction to the

hydrogen production apparatuses

2a and 2b are prevented.
[Fourth Embodiment]
Next, a hydrogen production system 400 according to the fourth embodiment will be described with reference to FIG. In FIG. 8, the same reference numerals as those in FIGS. 1 and 5 denote the same components, and detailed description thereof will be omitted.

In the hydrogen production system 400 of the present embodiment, the switching element 6 is removed from the configuration of the hydrogen production system 300 of the present embodiment shown in FIG. 5, and the hydrogen production apparatuses 2 (2a to 2n) are connected in series. In this configuration, the protective device 3 (3a to 3m) is provided on the wiring.

As the protection device 3 (3a to 3m) in FIG. For example, consider a case where a configuration in which three hydrogen production apparatuses 2a to 2c are connected in parallel is switched to a parallel connection of only one hydrogen production apparatus 2a, that is, two apparatuses are stopped. First, electric power derived from renewable energy is input to the hydrogen production apparatuses 2a to 2c to produce hydrogen gas. At this time, the switching elements S101 to S103 and S201 to S203 are in the on state, and the protection devices 3a to 3c are in the high resistance state. Here, the two apparatuses (

hydrogen production apparatuses

2b and 2c) are stopped, the switching elements S102 and S203 are left in the on state, S202 and S103 are in the off state, and the

hydrogen production apparatuses

2b and 2c are configured in series. At the same time, the voltage within the range of Eeq or ΔE is swept to the

hydrogen production apparatuses

2b and 2c, and the resistance value of the protection apparatus 3b in the range where no current flows to the

hydrogen production apparatuses

2b and 2c is controlled. Reaction can be prevented or suppressed.

In this manner, the hydrogen production system 400 according to the fourth embodiment also copes with fluctuations in the supply amount of renewable energy, suppresses deterioration of the hydrogen production apparatus, and uses hydrogen gas without waste using renewable energy. Can be manufactured.
[Fifth Embodiment]
Next, a hydrogen production system 500 according to the fifth embodiment will be described with reference to FIG. 9, the same reference numerals as those in FIG. 1 denote the same components, and the detailed description thereof is omitted.

The hydrogen production system 500 of this embodiment shows a system configuration capable of storing hydrogen produced by the hydrogen production apparatus 2 (2a to 2n) as saturated hydrocarbons. Specifically, the hydrogen production system 100 shown in FIG. 1 further includes a buffer tank 9, a hydrogenation device 10, a saturated hydrocarbon storage tank 11, and an unsaturated hydrocarbon storage tank 12. is there.

Although the specific configuration of the buffer tank 9 is not particularly limited, the purpose is to increase the purity of the hydrogen generated in the hydrogen production apparatus 2 by removing water from the hydrogen before being supplied to the hydrogenation apparatus 10 (described later). An apparatus for removing moisture is exemplified. For example, a gas-liquid separator or the like corresponds to this. The specific configuration of the gas-liquid separation device is not particularly limited, but for example, gas-liquid separation by cooling, a hydrogen separation membrane, or the like can be used, and it is preferable to use a hydrogen separation membrane. The removed water is circulated in the hydrogen production apparatus 2 and is electrolyzed.

And the hydrogen after moisture removal is supplied to the hydrogenation apparatus 10 connected by gas piping. In addition, although hydrogen after moisture removal may be directly supplied to the hydrogenation apparatus 10, the hydrogenation efficiency can be further improved by supplying this hydrogen to the hydrogenation apparatus 10 via a pressure regulator. In other words, renewable energy can be stored without waste.

Although not shown in the embodiment shown in FIG. 9, this hydrogen can be temporarily stored in a hydrogen storage means such as a high-pressure tank. The specific configuration of the hydrogen gas hydrogen storage means is not particularly limited. For example, a known hydrogen cylinder, a pressure vessel for high pressure gas, or the like can be used. These may be provided alone or in any combination of two or more. Examples of the material constituting the hydrogen storage means include, for example, a steel plate, a plastic reinforced with carbon fiber, and the like, and it is particularly preferable to use a pressure resistant container having a pressure higher than that applied to the hydrogen production apparatus 2.

Also, a hydrogen storage alloy can be used as the hydrogen storage means. Examples of the hydrogen storage alloy include an AB5 type alloy such as a rare earth metal-nickel system, and an alloy having a body-centered cubic (BCC) structure such as a titanium system or a chromium system. By making these hydrogen storage alloys exist in the above-mentioned container or the like, the hydrogen storage amount can be increased. Moreover, when storing the same volume of hydrogen, the pressure of the hydrogen storage means may be reduced.

It is preferable that the buffer tank 9 and the hydrogenation apparatus 10 are connected by a gas pipe (pipeline). However, it is not always necessary that these are connected by gas piping. For example, the produced hydrogen may be transported to the hydrogenation apparatus 10 (that is, supplied to the hydrogenation apparatus 10) using a high-pressure tank or the like.

The hydrogenation device 10 adds hydrogen produced by the hydrogen production device 2 to unsaturated hydrocarbons. The hydrogenation apparatus 10 is connected to the buffer tank 9 and the gas pipe as described above, and is connected to a saturated hydrocarbon storage tank 11 and an unsaturated hydrocarbon storage tank 12 (both described later) by a liquid pipe. Yes. Therefore, the unsaturated hydrocarbon is supplied from the unsaturated hydrocarbon storage tank 12 to the hydrogenation apparatus 10.

Although the specific kind of unsaturated hydrocarbon used in the hydrogenation apparatus 10 is not particularly limited, for example, a liquid aromatic compound such as methylbenzene can be suitably used. For example, when methylbenzene is used as the unsaturated hydrocarbon, the resulting saturated hydrocarbon is methylcyclohexane, and the amount of hydrogen molecules that can be stored per mole of methylbenzene is 2.5 moles. However, depending on the conditions at the time of the addition reaction, for example, anthracene, phenanthrene, and the like may become liquid. When performing the addition reaction under such conditions, these aromatic compounds may be used. By using these aromatic compounds, more hydrogen can be stored.

Since such an aromatic compound is liquid at room temperature, it can be easily stored, and there is an advantage that a reaction interface becomes large when a hydrogenation reaction is performed. Further, by using an aromatic compound, the amount of hydrogen that can be added per molecule of the aromatic compound can be increased, and more hydrogen can be stored with a smaller amount of unsaturated hydrocarbons. In addition, an unsaturated hydrocarbon may be used by 1 type and may use 2 or more types by arbitrary ratios and combinations.

There is no particular limitation on the specific method of adding hydrogen to the unsaturated hydrocarbon in the hydrogenation apparatus 10. However, from the viewpoint of low cost and short reaction time, hydrogen is usually added to the unsaturated hydrocarbon using a catalyst. Examples of such a catalyst include metals such as Ni, Pd, Pt, Rh, Ir, Re, Ru, Mo, W, V, Os, Cr, Co, and Fe, and alloys thereof. The metal which comprises a catalyst, and those alloys may be used individually by 1 type, and 2 or more types may be used by arbitrary ratios and combinations.

In addition, these catalysts are preferably finely divided from the viewpoint of further cost reduction by reducing the amount of catalyst and an increase in reaction surface area. When a finely divided catalyst is used, it may be supported on an arbitrary carrier from the viewpoint of preventing a reduction in surface area due to aggregation of the fine particle catalyst. When the catalyst is supported on the carrier, the method for supporting is not particularly limited, and for example, a coprecipitation method, a thermal decomposition method, an electroless plating method, or the like can be used. Also, the type of carrier is not particularly limited, and for example, in addition to carbon materials such as activated carbon, carbon nanotubes, and graphite, alumina silicate such as silica, alumina, and zeolite can be used. One type of carrier may be used, or two or more types may be used in any ratio and combination.

The hydrogenation reaction conditions for unsaturated hydrocarbons in the hydrogenation apparatus 10 are not particularly limited and may be set arbitrarily. For example, hydrogen can be added even at a reaction temperature of room temperature (about 25 ° C.), but it is preferable to add hydrogen at a temperature of about 100 ° C. to 400 ° C. from the viewpoint of shortening the reaction time.

In addition, although the reaction pressure during the addition reaction is not particularly limited, the pressure during hydrogen addition is 1 to 50 atm (gauge pressure) from the viewpoint of increasing the efficiency of the addition reaction and shortening the reaction time. That is, the pressure is preferably 0.1 MPa or more and 5 MPa or less. Therefore, a pressure regulator can be provided between the buffer tank 9 and the hydrogenation device 10 in order to increase the pressure during hydrogen addition.

As described above, hydrogen can be added to the unsaturated hydrocarbon, and a saturated hydrocarbon is obtained. The obtained saturated hydrocarbon (so-called organic hydride) is stored in a saturated hydrocarbon storage tank 11 described later.

The saturated hydrocarbon storage tank 11 stores the saturated hydrocarbon generated in the hydrogenation apparatus 10. Therefore, the saturated hydrocarbon storage tank 11 is connected to the hydrogenation apparatus 10 by liquid piping. Further, between the saturated hydrocarbon storage tank 11 and the hydrogenation apparatus 10, an apparatus for controlling the supply amount of saturated hydrocarbons to the saturated hydrocarbon storage tank 11, such as a flow rate adjusting valve and a flow meter, is provided. Also good.

The unsaturated hydrocarbon storage tank 12 stores unsaturated hydrocarbons supplied to the hydrogenation apparatus 10. The unsaturated hydrocarbon storage tank 12 is connected to the hydrogenation apparatus 10 by a liquid pipe. Moreover, you may provide the apparatus for controlling the supply amount to the hydrogenation apparatus 10 from the unsaturated hydrocarbon storage tank 12, for example, a flow control valve, a flowmeter, etc.

In the present embodiment, the hydrogen production system 100 shown in FIG. 1 further includes a buffer tank 9, a hydrogenation device 10, a saturated hydrocarbon storage tank 11, and an unsaturated hydrocarbon storage tank 12. Although shown, the hydrogen production system described with reference to FIGS. 4, 5, and 8 further includes a buffer tank 9, a hydrogenation device 10, a saturated hydrocarbon storage tank 11, and an unsaturated hydrocarbon storage tank 12. Configuration can be adopted.

In the above embodiment, the hydrogen production system that produces hydrogen by the water electrolysis apparatus using the fluctuating power from the power generation device that converts the renewable energy into electric power has been described as an example. However, the fluctuating power is derived from the renewable energy. It is not limited to the electric power. For example, it may be a hydrogen production system that uses surplus power of the power system as fluctuating power supplied to the water electrolysis apparatus.

1 Renewable energy power generation device, 2 Hydrogen production device, 3 Protection device, 4-7 switching element, 8 Control device, 9 Buffer tank, 10 Hydrogenation device, 11 Saturated hydrocarbon storage tank, 12 Unsaturated hydrocarbon storage tank

Claims

A plurality of hydrogen production apparatuses that are connected in series or in parallel and produce hydrogen gas using DC power;
A switching element for switching the connection configuration of the plurality of hydrogen production apparatuses;
Among the plurality of hydrogen production apparatuses, a voltage application unit that applies a voltage to a hydrogen production apparatus that stops production of hydrogen gas by switching a connection configuration using the switching element;
And a control device for controlling the switching element and the voltage application means.
The hydrogen production system according to claim 1,
The said voltage application means is comprised with an external power supply and the switching element which supplies the said external power supply to the said hydrogen production apparatus, or cuts off from the said hydrogen production apparatus, The hydrogen production system characterized by the above-mentioned.
The hydrogen production system according to claim 2,
The control device controls the switching element so that the external power supply applies a voltage to the hydrogen production apparatus that stops production of hydrogen gas by switching the connection configuration by the switching element. Hydrogen production system.
The hydrogen production system according to claim 1,
The hydrogen application system, wherein the voltage application means includes a variable resistor.
The hydrogen production system according to claim 4,
The control device performs control to increase the resistance value of the variable resistor connected in series with the hydrogen production device that stops production of hydrogen gas by switching the connection configuration by the switching element. system.
The hydrogen production system according to claim 1,
A buffer tank for purifying the hydrogen gas produced by the hydrogen production device;
A hydrogenation device that generates saturated hydrocarbons by adding hydrogen gas supplied from the buffer tank to unsaturated hydrocarbons;
Saturated hydrocarbon storage means for storing saturated hydrocarbons produced by the hydrogenation device;
A hydrogen production system comprising:
The hydrogen production system according to claim 1,
The direct current power is supplied by a power generation device that converts renewable energy into electrical energy.