JP2005126792A - Hydrogen production equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide hydrogen production equipment capable of widening an ordinary operation range without enlarging cell stacks, and also using a generator having satisfactory energy efficiency as an electric power source. <P>SOLUTION: The hydrogen production equipment is provided with: a water electrolysis apparatus 3 having a plurality of cell stacks C1 to C4 composed of a plurality of water electrolysis cells; wherein the cell stacks C1 to C4 are mutually connected in series or in parallel electrically; a power supply means of supplying power to the water electrolysis apparatus 3; a voltage control part 16 of variably controlling the voltage of the power fed to the water electrolysis apparatus 3; and a stack number control part 17 of selecting the number of the stacks in the water electrolysis apparatus 3 in such a manner that the voltage and electric current acted on each cell stack C1 to C4 are controlled to prescribed ranges in accordance with the power supplied to the water electrolysis apparatus 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydrogen production facility provided with a water electrolysis device that generates hydrogen using power generated by a generator as a power source.

  Hydrogen is attracting attention as a non-polluting fuel used in automobiles and the like, and a water electrolysis device that generates hydrogen by electrolyzing water is used as a means for obtaining hydrogen. The electrolysis unit of the water electrolysis apparatus is configured by a cell stack in which a predetermined number of water electrolysis cells are stacked. FIG. 5 is a diagram illustrating IV characteristics of the water electrolysis apparatus. As can be seen from this figure, in the water electrolysis apparatus, the higher the applied voltage, the more current flows. The amount of hydrogen (output) generated in proportion to the magnitude of the current also increases. However, if high current is obtained by increasing the current, the amount of Joule heat generated in the electrolysis part of the water electrolysis device increases, and accordingly, the energy efficiency of the water electrolysis device decreases, and at the same time, the water electrolysis cell As a result, the life of the water electrolysis cell is reduced or damaged. Therefore, the water electrolysis apparatus is operated by limiting the voltage / current range so that it can be within the normal range shown by the solid line in the figure so that hydrogen can be produced with as high energy efficiency as possible. In addition, it is common to operate | move in the voltage range of 1.5-2.0V per water electrolysis cell.

  By the way, in recent years, with respect to high-efficiency operation of hydrogen production facilities, a technique for utilizing the output of a solar cell with high efficiency for operation of a water electrolysis system has been proposed in Patent Document 1 below. The “operating method of the water electrolysis system” of Patent Document 1 is configured as shown in FIG. 6, and includes a water electrolysis device 30 having a cell group including a plurality of water electrolysis cells 31 to 38, and a power source for the cell group. In operating a water electrolysis system including a certain solar cell 40, the solar cell 40 and the cell group are electrically connected so that the output of the solar cell 40 can be directly supplied to the cell group. The number of water electrolysis cells 31 to 38 used is selected so that the maximum output can be used. The IV characteristics of the solar cell vary depending on the temperature, and the IV characteristics of the water electrolysis apparatus vary depending on the number of water electrolysis cells connected in series in the cell group. Accordingly, the temperature of the solar cell is detected by the temperature detection unit 21, the number of the most efficient water electrolysis cells used is selected by the control device 22 according to the IV characteristics of the solar cell at that temperature, and the switch is switched by the control device 22. Is configured to constitute a water electrolysis apparatus comprising a desired number of water electrolysis cells.

JP 2001-335982 A

  In order to keep the voltage acting on each water electrolysis cell within the normal range, the number of water electrolysis cells can be increased or the cell stack itself can be enlarged by increasing the cell area. A method to make it possible is considered. However, when the cell stack itself is enlarged, it is difficult to cool the water electrolysis cell located at the center of the stack, and it is difficult to balance the voltage acting on each water electrolysis cell.

  On the other hand, in “Operation Method of Water Electrolyte System” of Patent Document 1, the energy efficiency of the water electrolysis apparatus is not taken into consideration, focusing on the efficient use of the output of the solar cell exclusively. The invention of Patent Document 1 is a hydrogen production technology that uses the output of a solar cell whose output characteristics change depending on temperature. When power is generated by a generator such as wind power generation, output voltage control of the generated output is performed. Therefore, the concept is different from that of solar cells. The invention of Patent Document 1 only determines the number of cells used when selecting the cell units to be used, and does not consider which cell unit is used. Therefore, when the load is concentrated on a specific cell unit, there is a problem that the life of the cell unit is reduced.

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a hydrogen production facility using a generator as a power source, which can widen the normal operation range without enlarging the cell stack and is energy efficient.

  In order to achieve the above object, the hydrogen production facility of the present invention has a plurality of cell stacks in which a plurality of water electrolysis cells are stacked, and the cell stacks are electrically connected to each other in series or in parallel. An electrolyzer, power supply means for supplying power to the water electrolyzer, a voltage control unit for variably controlling the voltage of power supplied to the water electrolyzer, and the power supplied to the water electrolyzer, And a stack number control unit that selects the number of cell stacks used in the water electrolysis apparatus so that the voltage and current acting on the cell stack are within a predetermined range.

According to the above configuration, the number of cell stacks used in the water electrolysis device is selected so that the voltage and current acting on each cell stack are within a predetermined range according to the power supplied to the electrolysis device. The voltage and current acting on can be set within the normal range. As a result, an increase in Joule loss can be suppressed to prevent a decrease in energy efficiency, and the degree of freedom of operation points can be expanded, so that highly flexible operation is possible.
Further, since each cell stack is unitized by configuring the water electrolysis apparatus to include a plurality of cell stacks, the unit replacement operation is facilitated. Further, the unit can be replaced even during operation of the water electrolysis apparatus.

  In the water electrolysis facility of the present invention, preferably, the stack number control unit reduces the number of used cell stacks from N + 1 to N when the number of used cell stacks is increased from N to N + 1. Control is performed with a hysteresis characteristic that is higher than the current power.

  By giving such a hysteresis characteristic when increasing or decreasing the number of cell stacks used, frequent switching can be avoided and an excessive burden on the switch circuit and the cell stack can be suppressed.

  In the hydrogen production facility of the present invention, preferably, the stack number control unit stops the operation of the cell stack having the longest operation time during the operation state when the number of use of the cell stack is decreased. Take control. In the water electrolysis facility of the present invention, preferably, the stack number control unit controls the water electrolysis unit having the longest stop time during the operation state when the number of use of the cell stack is increased. I do.

  As a result, the load is not concentrated on a specific cell stack, and the operation time of each cell stack is averaged, so that it is possible to prevent a decrease in the life of the cell stack.

  As described above, according to the present invention, the normal operation range can be widened without enlarging the cell stack, water electrolysis can be performed with high energy efficiency, and the cell stack can be easily replaced. In addition, an excellent effect can be obtained such that the life of the water electrolysis apparatus can be prevented from being reduced.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of the invention will be described in detail with reference to FIGS.

  FIG. 1 is a schematic configuration diagram of a hydrogen production facility according to the present invention. As shown in this figure, the hydrogen production facility according to the present invention includes a wind power generator 1, a rectifier 2, a water electrolysis device 3, and a control device 15.

  The wind power generator 1 includes a windmill 1a and a power generator 1b. The rotor of the power generator 1b is connected to the shaft of the windmill 1a. When the windmill 1a is rotated by wind energy, the generator 1b rotates the windmill 1a. The rotor rotates in the stator according to the speed, and AC power is output from the stator. A rectifier (AC / DC converter) 2 is connected to the stator of the generator 1b, and the AC power generated by the generator 1b is converted into DC power by the rectifier 2. Thus, the wind power generator 1 and the rectifier 2 constitute power supply means for supplying power to the water electrolysis apparatus. In addition to the wind power generator, the type of the power generator may be a hydroelectric generator, a thermal power generator, or the like. Also, it does not matter whether the generator is an AC generator or a DC generator.

  The water electrolysis apparatus 3 is configured to generate hydrogen using the generated power converted from AC power to DC power by the rectifier 2 as a power source, and has cell stacks C1 to C4 in which a plurality of water electrolysis cells are stacked. It has a configuration. Switches S1 to S8 are connected to the positive terminal side and the negative terminal side of the cell stacks C1 to C4, respectively. The positive terminal side of the switches S1 to S4 is connected to the positive terminal side of the rectifier 2 via the conductor 4, and the negative terminal side of the switches S5 to S8 is connected to the negative terminal side of the rectifier 2 via the conductor 5. Has been. Further, between the minus terminal side of the cell stack C1 and the plus terminal side of the cell stack C2, between the minus terminal side of the cell stack C2 and the plus terminal side of the cell stack C3, between the minus terminal side of the cell stack C3 and the cell stack C4. Switches S9, S10, S11, and S12 are sequentially connected between the positive terminal side and between the positive terminal side of the cell stack C1 and the negative terminal side of the cell stack C4. As will be described later, the cell stacks C1 to C4 are electrically connected to each other in parallel or in series by a combination of opening and closing the switches S1 to S12.

  The control device 15 includes a voltage control unit 16 and a stack number control unit 17. The voltage control unit 16 has a function of variably controlling the voltage of the generated power supplied to the water electrolysis device 3. This voltage control can be performed, for example, by adjusting the excitation voltage of the exciter of the generator 1b or by adjusting the firing angle of the rectifier 2. Thereby, the voltage applied to the water electrolysis apparatus 3 can be adjusted freely.

  The stack number control unit 17 causes the voltage and current acting on each cell stack to be within a predetermined range (within the voltage and current range operable in each cell stack) according to the power supplied to the water electrolysis device. It has a function of selecting the number of cell stacks used in the water electrolysis apparatus 3. Since the operable voltage and current range in one cell stack can be obtained from energy efficiency and current density, each cell stack is connected in series and in parallel for each number of used cell stacks. The range of operable voltage and current is obtained, the number of cell stacks used corresponding to a certain power range is set, and stored in the stack number control unit 17. Then, the stack number control unit 17 determines the optimum number of cell stacks used in the water electrolysis device 3 based on the power value supplied to the water electrolysis device 3 and the stored voltage and current range of operation of the cell stack. In addition to selection, a switch open / close signal for configuring the number of used cell stacks is output. The switches S <b> 1 to S <b> 12 perform a predetermined opening / closing operation based on the switch opening / closing signal from the stack number control unit 17. When the power value supplied to the water electrolysis device 3 increases and exceeds the operable voltage and current range with the current number of cell stacks used, a switch open / close signal is output to increase the number of cell stacks used. The switches S1 to S12 are activated.

  For example, when the cell stacks C1 and C2 are used in series connection, a switch open / close signal may be output so that the switches S1, S6, and S9 are closed and the other switches are opened. When increasing the number of cell stacks used, for example, when adding a cell stack C3, a switch open / close signal may be output so that the switches S1, S7, S9, S10 are closed and the other switches are opened.

  On the other hand, when the cell stacks C1 and C2 are used in parallel connection, the switches S1, S2, S5, and S6 may be closed and the other switches may be opened. When increasing the number of cell stacks used, for example, when adding a cell stack C3, a switch open / close signal may be output so as to further close the switches S3 and S7.

  2 and 3 show the IV characteristics of the water electrolysis apparatus according to the present invention. FIG. 2 shows the case where the cell stacks are connected in series. FIG. 3 shows the case where the cell stacks are connected in parallel. Show. In both figures, three IV curves (1) to (3) indicate IV curves for each cell stack use number, and the cell stack use number is one, two, and three in order from the left. In each IV curve, the solid line portion indicates the operable voltage and current range for each cell stack number, and the dotted line portion indicates the other range. As shown in this figure, for example, when the voltage and current are at a point P1 within the operable range, the number of cell stacks is not changed by the stack number control unit 17, and the voltage control unit 16 exclusively uses the desired voltage. It is controlled to become. When the voltage and current become point P2 and the operating range is no longer exceeded when the number of used cell stacks is two, the stack number control unit 17 changes the number of used cell stacks to 3, and the operating point is within the operating range. Maintained within. As a result, an increase in Joule loss in the water electrolysis apparatus can be suppressed to prevent a decrease in energy efficiency, and the degree of freedom of the operation point can be expanded and a highly flexible operation can be obtained. .

  Further, as shown in FIGS. 2 and 3, it is preferable to provide a hysteresis characteristic when changing the number of used cell stacks under the control of the stack number control unit 17. That is, the hysteresis characteristic is such that the power when the number of used cell stacks is increased from N (N is an integer of 1 or more) to N + 1 is higher than the power when the number of used cell stacks is decreased from N + 1 to N. Change the number of used cell stacks by performing the given control. As described above, when the number of cell stacks used is increased or decreased, by providing hysteresis characteristics, frequent switching of the switches S1 to S12 is avoided, and the switches S1 to S12 and the cell stacks C1 to C4 are overloaded. Can be reduced.

  FIG. 4 shows a conceptual diagram when the stack number control unit 17 increases or decreases the number of cell stack usage. In this figure, C1 to C4 indicate the cell stacks C1 to C4 in FIG. In addition, a cell stack decorated with diagonal lines indicates that it is in operation, and other cell stacks that are not decorated with diagonal lines indicate that it is stopped. In this figure, it is assumed that time has passed in the order of (a) → (b) → (c) → (d). As shown in this figure, when increasing the number of cell stacks used, the stack number control unit 17 operates the water electrolysis unit having the longest stop time during the operation state and sets the number of cell stacks used. When decreasing, control is performed to stop the operation of the cell stack having the longest operation time during the operation state. That is, in the example of FIG. 4, when the cell stacks C1 and C2 are first operated (a) and then the number of cell stacks is increased, the cell stack C3 is operated (b) and then the number of cell stacks is decreased. When the cell stack C1 having a long operation time is stopped (c) and then the number of cell stacks is increased, the cell stack C4 having the shortest operation time is operated (d). Thus, since the cell stacks C1 to C4 are circulated and operated, the operation time of each cell stack is averaged. As a result, the load is not concentrated on a specific cell stack, and the life of the cell stack can be prevented from being reduced.

  According to the hydrogen production facility of the present invention, in addition to the above-described effects, each cell stack is unitized by configuring the water electrolysis apparatus 3 to include a plurality of cell stacks, so that the unit replacement operation is facilitated. The effect that the unit can be replaced even during the operation of the water electrolysis apparatus is obtained.

  In the present embodiment described above, the number of cell stacks is four (C1 to C4). However, the number of cell stacks is not limited to this, and the power supply capability of the power supply means and the required hydrogen production capability are not limited. The number can be increased or decreased as appropriate. Further, the arrangement of the switches S1 to S12 is not limited to that described above, and can be appropriately changed as long as the cell stacks can be electrically connected in series or in parallel.

  In FIG. 1, depending on the arrangement of the switches, it is possible to connect each cell stack by mixing serial connection and parallel connection. Further, the example of FIG. 4 described above is for conceptually explaining the increase / decrease in the number of used cell stacks by the stack number control unit 17, and the number of cell stacks and the order of the increase / decrease are limited to the above-described contents. Is not to be done.

  In addition, this invention is not limited to embodiment mentioned above, Of course, a various change can be added in the range which does not change the summary of this invention.

It is a schematic block diagram which shows embodiment of this invention. It is a figure which shows the IV characteristic of the water electrolysis apparatus at the time of connecting a cell stack in series. It is a figure which shows the IV characteristic of the water electrolysis apparatus at the time of connecting a cell stack in parallel. It is a conceptual diagram for demonstrating increase / decrease in the number of cell stack use. It is a figure which shows IV characteristic of a general water electrolysis apparatus. It is a block diagram which shows invention of patent document 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wind generator 1a Windmill 1b Generator 2 Rectifier 3 Water electrolysis apparatus 4, 5 Conductor 15 Control apparatus 16 Voltage control part 17 Stack number control part C1-C4 Cell stack S1-S12 Switch

Claims (4)

A water electrolysis apparatus comprising a plurality of cell stacks formed by laminating a plurality of water electrolysis cells, the cell stacks being electrically connected to each other in series or in parallel;
Power supply means for supplying power to the water electrolysis device;
A voltage control unit that variably controls the voltage of power supplied to the water electrolysis device;
A stack number control unit that selects the number of cell stacks used in the water electrolysis device so that the voltage and current acting on each cell stack are within a predetermined range in accordance with the power supplied to the water electrolysis device. This is a hydrogen production facility.   The stack number control unit has a hysteresis characteristic such that the power when increasing the number of used cell stacks from N to N + 1 is higher than the power when decreasing the number of used cell stacks from N + 1 to N + 1. The hydrogen production facility according to claim 1, wherein control is performed.   The said stack number control part performs control which stops the operation | movement of the cell stack with the longest operation time between the operation states, when reducing the number of use of a cell stack. Hydrogen production facility. 2. The hydrogen production according to claim 1, wherein when the number of used cell stacks is increased, the stack number control unit performs control to operate the cell stack having the longest stop time during the operation state. Facility.

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