JP7306623B2 - Thermal management method in hydrogen utilization system - Google Patents

Description

The present invention relates to a method of thermal management in a hydrogen utilization system.

In recent years, photovoltaic power generation has spread rapidly, but there is concern that the amount of power supplied by photovoltaic power generation will exceed the amount of power demand. In that case, it is desirable that the energy that is output from the photovoltaic power generation and discarded using a storage battery or the like is stored as surplus power. As a method for storing surplus electric power, a method using a hydrogen storage alloy is attracting attention. In the method of storing energy using a hydrogen storage alloy, the conversion efficiency of energy during release to energy during storage is lower than in the method using a storage battery. However, the method of storing energy using a hydrogen storage alloy is suitable for large-capacity and long-term energy storage.

For example, Patent Literature 1 discloses a power supply system that uses electric power to produce and store hydrogen, and that includes a hydrogen utilization system that generates power using hydrogen. In this power supply system, consumers connected to a power system are provided with a hydrogen production device, a hydrogen storage device, a fuel cell, a load monitor device, and a monitoring control device. Further, in the power supply system disclosed in Patent Document 1, hydrogen is produced, stored, and used based on demand forecast and load fluctuation.

Further, Patent Document 2 discloses a power supply system including a hydrogen utilization system that produces, stores, and utilizes hydrogen from natural energy. This power supply system includes a natural energy power generation device such as a solar panel, a power conditioner device, a storage battery, a hydrogen production device, a hydrogen storage device, and a fuel cell. Further, the power supply system disclosed in Patent Document 2 supplies power to the storage battery and the hydrogen production device based on the predicted value of the power generation amount of the natural energy power generation device during the day and the predicted value of the power demand of the facility. Determine quantity. The power supply system also determines the amount of power to be supplied from the storage battery to the facility at night and the amount of power to be supplied from the fuel cell to the facility.

Japanese Patent Application Laid-Open No. 2003-061251 Japanese Patent No. 6189448

In the hydrogen utilization systems of Patent Documents 1 and 2 described above, in order to efficiently release hydrogen using the hydrogen storage alloy, that is, to generate power with the fuel cell, the pressure inside the tank containing the hydrogen storage alloy is It must be well above the operating pressure of the fuel cell. If the pressure inside the tank is lower than the operating pressure of the fuel cell, it is necessary to heat the hydrogen-absorbing alloy to increase the pressure inside the tank.

A method of heating the hydrogen storage alloy includes a method of using exhaust heat from the fuel cell. However, in order to obtain exhaust heat from the fuel cell, electric power for starting the fuel cell, that is, hydrogen release from the hydrogen absorbing alloy is required. Therefore, exhaust heat from the fuel cell cannot be used in the initial stage of hydrogen release by the hydrogen storage alloy, and a heat source for heating and a heat storage tank must be provided in the tank. As a result, the tank becomes large, and it takes time and cost to install the heat source and heat storage tank inside the tank.

The present invention provides a heat management method in a hydrogen utilization system with high utilization efficiency.

The hydrogen utilization system of the present invention comprises a hydrogen production device that produces hydrogen using surplus power of renewable energy, and a hydrogen storage alloy that can store the hydrogen produced by the hydrogen production device and can release the stored hydrogen. a hydrogen storage device provided with a plurality of hydrogen storage alloy tanks having a A heat medium flow path configured to be able to supply the heat generated in a plurality of the hydrogen storage alloy tanks, the supply or stop of the hydrogen, the surplus electric power and the generated power, and the flow of the heat medium in the heat medium flow path and a control device configured to be able to control the plurality of hydrogen-absorbing alloy tanks having different heat capacities.

According to the hydrogen utilization system described above, since the hydrogen storage device includes a plurality of hydrogen storage alloy tanks having different heat capacities, the total heat capacity of the hydrogen storage alloy tanks can be changed according to the operating conditions. For example, if multiple hydrogen-absorbing alloy tanks are heated and cooled by the heat from the hydrogen production equipment, the heat generated when absorbing hydrogen in the hydrogen-absorbing alloy, and the heat absorbed by the hydrogen-absorbing alloy, all the hydrogen-absorbing alloy tanks should be The total heat capacity of the hydrogen storage alloy tank (hydrogen storage device) can be increased by heating and cooling. In addition, when multiple hydrogen-absorbing alloy tanks are heated by the heat from the fuel cell, only the hydrogen-absorbing alloy tanks that are releasing hydrogen are to be heated, and the total heat capacity of the hydrogen-absorbing alloy tanks is minimized. can be suppressed. This increases the usage efficiency of the hydrogen utilization system.

The heat management method in the hydrogen utilization system of the present invention is the heat management method in the above-described hydrogen utilization system, wherein the heat capacity is maintained until the total amount of hydrogen stored in the plurality of hydrogen-absorbing alloy tanks reaches at least a predetermined storage amount. a hydrogen absorbing step of supplying the hydrogen produced by the hydrogen production apparatus to the hydrogen absorbing alloy tanks in order from the hydrogen absorbing alloy tanks with the smallest values to absorb the hydrogen; and a first heat medium circulation step for circulating.

According to the above-described heat management method in the hydrogen utilization system, in the hydrogen absorption step, hydrogen produced by the hydrogen production apparatus is absorbed in order from the hydrogen absorption alloy tank with the smallest heat capacity. The hydrogen absorbing step is completed when the total amount of hydrogen absorbed in the plurality of hydrogen absorbing alloy tanks reaches at least a predetermined amount of hydrogen absorbed. In the first heat medium circulation step, the heat medium is circulated through all the hydrogen-absorbing alloy tanks including those not used in the hydrogen-absorbing step. Used for heating hydrogen storage alloy tanks. Also, the hydrogen storage alloy tank, which has a large heat capacity, functions as a heat reservoir. As a result, the hydrogen storage alloys in all of the hydrogen storage alloy tanks can be easily maintained at a temperature higher than the temperature at which hydrogen can be released, and the use efficiency of the hydrogen utilization system is increased.

The heat management method in the hydrogen utilization system of the present invention is the heat management method in the above-described hydrogen utilization system, wherein the heat capacity is maintained until the total amount of hydrogen released from the plurality of hydrogen storage alloy tanks reaches at least a predetermined release amount. a hydrogen releasing step of releasing the stored hydrogen to the fuel cell in order from the hydrogen storage alloy tank with a smaller value; a second heat medium circulation step of circulating a heat medium; and circulating the heat medium through the hydrogen-absorbing alloy tank releasing the hydrogen and the fuel cell after exhaust heat from the fuel cell can be recovered. and a third heat medium circulation step.

According to the heat management method in the hydrogen utilization system described above, in the hydrogen release step, the hydrogen stored in the hydrogen storage alloy is released in order from the hydrogen storage alloy tank with the smallest heat capacity. The hydrogen releasing step is completed when the total amount of released hydrogen from the plurality of hydrogen storage alloy tanks reaches at least a predetermined amount of released hydrogen. In the second heat medium circulation step, the heat medium is circulated through all the hydrogen-absorbing alloy tanks including, for example, the hydrogen-absorbing alloy tanks that have not been used during hydrogen absorption. At this time, for example, heat is supplied from a hydrogen-absorbing alloy tank with a large heat capacity that was not used when hydrogen was absorbed, and the heat absorption of the plurality of hydrogen-absorbing alloy tanks releasing hydrogen is absorbed by all the hydrogen-absorbing alloy tanks. contributes to the cooling of This suppresses the temperature drop of the hydrogen storage alloy tank due to the release of hydrogen. When it becomes possible to recover exhaust heat from the fuel cell, the second heat medium circulation process is shifted to the third heat medium circulation process. In the third heat medium circulation step, the heat medium is circulated only in the hydrogen storage alloy tank that is releasing hydrogen among the plurality of hydrogen storage alloy tanks and in the fuel cell. As a result, the heat capacity of the hydrogen-absorbing alloy tank to be heated by the heat from the fuel cell is minimized, and the hydrogen-absorbing alloy tank to be heated is quickly heated. Therefore, the usage efficiency of the hydrogen utilization system is enhanced.

According to the heat management method in the hydrogen utilization system of the present invention, the utilization efficiency of the hydrogen utilization system can be enhanced.

1 is a schematic configuration diagram of a hydrogen utilization system according to one embodiment of the present invention; FIG. 2 is a chemical formula showing a hydrogen absorption/desorption reaction in the hydrogen storage alloy of the hydrogen utilization system shown in FIG. 1; 2 is an example of a PCT diagram of the hydrogen storage alloy of the hydrogen utilization system shown in FIG. 1. FIG. 1 is a schematic diagram for explaining a heat management method for a hydrogen utilization system according to one embodiment of the present invention, and shows a state in which the operation mode of the hydrogen utilization system is the hydrogen production/occlusion mode. FIG. 1 is a schematic diagram for explaining a heat management method for a hydrogen utilization system according to one embodiment of the present invention, and shows a state in which the hydrogen utilization system is operating in a hydrogen release/fuel cell power generation mode; FIG. 1 is a schematic diagram for explaining a heat management method for a hydrogen utilization system according to one embodiment of the present invention, and shows a state in which the hydrogen utilization system is operating in a hydrogen release/fuel cell power generation mode; FIG.

Preferred embodiments of the hydrogen utilization system and the heat management method in the hydrogen utilization system of the present invention will be described below with reference to the drawings.

[Configuration of hydrogen utilization system]
A hydrogen utilization system according to one embodiment of the present invention is incorporated in a power supply system (not shown). The power supply system described above utilizes surplus power of renewable energy sources such as sunlight, wind power, and geothermal heat, and realizes, for example, ZEB (Zero Energy Building) of buildings. The power supply system described above includes a storage battery, which stores the above-described surplus power and discharges it based on the stored power amount.

As shown in FIG. 1, the hydrogen utilization system 200 of this embodiment includes a hydrogen production device 2, a hydrogen storage device 3, a fuel cell 4, a heat medium flow path 202, and a control device (not shown).

The hydrogen production device 2 is a device that produces hydrogen using surplus power of renewable energy, and includes an electrolytic cell 21 and a heat exchanger 22 . As shown in FIGS. 1 and 4, the electrolyzer 21 is supplied with driving electricity (generated power) E1, and electrolyzes pure water PW to produce hydrogen H1. An electric supply channel 211 , a pure water supply channel 216 , a hydrogen supply channel 221 , and heat medium supply channels 231 and 233 are connected to the electrolytic cell 21 . The electricity E1 is supplied to the electrolytic cell 21 through an electricity supply path 211 from a storage battery or the like of a power supply system (not shown). The pure water PW is supplied from a pure water supply device (not shown) to the electrolytic cell 21 through the pure water supply channel 216 . Hydrogen H1 produced in the electrolytic cell 21 is supplied to the hydrogen storage device 3 through the hydrogen supply channel 221 . A valve 251 is provided in the hydrogen supply path 221 .

The heat exchanger 22 is connected to the electrolytic cell 21 via heat medium supply paths 231 and 233, is connected to the first heat medium flow path 11 via a heat medium supply path 232, and is connected to the first heat medium flow path 11 via a heat medium supply path 234. It is connected to the second heat medium flow path 12 . The heat exchanger 22 exchanges heat between medium-temperature water (heat medium) HC1 and low-temperature water (heat medium) HC2. When the hydrogen H1 is produced as described above, the electrolytic cell 21 releases heat. The pure water PW warmed by the heat radiation of the electrolytic cell 21 is supplied to the heat exchanger 22 via the heat medium supply path 231 as medium temperature water HC1. The low temperature water HC2 is supplied from the first heat medium flow path 11 to the heat exchanger 22 through the heat medium supply path 232 . A valve 252 is provided in the heat medium supply path 232 .

The medium-temperature water HC1 cooled by heat exchange is returned to the electrolytic cell 21 through the heat medium supply path 233 as the low-temperature water HC3. The low-temperature water HC2 warmed by heat exchange is supplied to the second heat medium flow path 12 through the heat medium supply path 234 as medium-temperature water HC4. The type of the heat exchanger 22 is, for example, a plate type, a fin tube type, or the like, but is not particularly limited as long as heat can be exchanged between the medium temperature water HC1 and the low temperature water HC2.

The hydrogen storage device 3 is a device that stores the hydrogen H1 produced by the hydrogen production device 2 and releases the stored hydrogen H1 in a timely manner. I have. The hydrogen supply channel 221 on the downstream side of the valve 251 branches into three hydrogen supply channels 221-1, 221-2 and 221-3. The hydrogen H1 supplied from the hydrogen production device 2 is distributed to the hydrogen H1-1, H1-2, H1-3, and the hydrogen storage alloy tank 31 through the hydrogen supply paths 221-1, 221-2, 221-3. -1, 31-2, 31-3.

Hydrogen storage alloy tanks 31-1, 31-2, and 31-3 are capable of storing hydrogen H1-1, H1-2, and H1-3, respectively, and store hydrogen H1-1, H1-2, and H1-3. It has a hydrogen storage alloy that can be released. A hydrogen storage alloy performs one or both of hydrogen storage and release according to the reversible chemical formula (1) shown in FIG. n in the chemical formula (1) is a natural number representing the hydrogen storage capacity of the hydrogen storage alloy. The larger the natural number n, the greater the maximum hydrogen storage capacity of the hydrogen storage alloy. Hydrogen storage alloys, such as magnesium hydride (MgH ₂ ), titanium hydride (TiH ₂ ), vanadium hydride (VH ₂ ), and zirconium hydride (ZrH ₂ ), store hydrogen according to chemical formula (1) and There is no particular limitation as long as it is a substance that can perform one or both of the releases.

The hydrogen storage characteristics and hydrogen release characteristics of each hydrogen storage alloy of the hydrogen storage alloy tank 31-Z are represented, for example, by the pressure-composition isotherm diagram (PCT diagram) shown in FIG. In this embodiment, Z is a natural number from 1 to 3 and represents the number of the hydrogen storage alloy tank. The vertical axis of the PCT diagram shown in FIG. 3 represents the equilibrium pressure PH2 of hydrogen H1-Z at a certain temperature. The horizontal axis of the PCT diagram shown in FIG. 3 represents the hydrogen storage amount in each hydrogen storage alloy of the hydrogen storage alloy tank 31-Z, and is represented by the hydrogen concentration [mass %] in each hydrogen storage alloy.

When the pressure of hydrogen H1-Z is slowly increased while the temperature of the hydrogen-absorbing alloy in the hydrogen-absorbing alloy tank 31-Z is maintained at T degrees, the hydrogen concentration H/M changes from point Q1 to point Q2 shown in FIG. It rises to draw a curve of On the other hand, in the range from point Q1 to point Q2, the hydrogen molecules (hydrogen) adsorbed on the surface of the metal in each hydrogen-absorbing alloy of the hydrogen-absorbing alloy tank 31-Z dissociate as the equilibrium pressure PH2 increases. It becomes a hydrogen atom (hydrogen) and dissolves in the metal to form a solid solution. In the range from point Q1 to point Q2, there is a solid solubility limit, so even if the pressure of hydrogen H1-Z is increased, the hydrogen concentration H/M does not increase much.

When the hydrogen concentration H/M reaches point Q2 shown in FIG. 3, the metal in the solid solution reacts with the dissolved hydrogen atoms to form a metal hydride. At point Q3 shown in FIG. 3, each hydrogen storage alloy in the hydrogen storage alloy tank 31-Z is entirely metal hydride. Between point Q2 and point Q3, the solid solution and the metal hydride coexist in each hydrogen storage alloy in the hydrogen storage alloy tank 31-Z, and the pressure of hydrogen H1-Z is constant. The region from point Q2 to point Q3 is called a plateau region.

When the pressure of hydrogen H1-Z is lowered from point Q4, a plateau region appears at the time of desorption as well as at the time of absorption of hydrogen H1-Z. There is a differential pressure called hysteresis in the equilibrium pressure PH2 in each plateau region during absorption and release of hydrogen H1-Z. Normally, the equilibrium pressure PH2 in the plateau region during absorption of hydrogen H1-Z is higher than the equilibrium pressure PH2 in the plateau region during release of hydrogen H1-Z.

The hydrogen storage alloy tanks 31-1, 31-2 and 31-3 shown in FIG. 1 have different heat capacities. That is, the equilibrium pressures PH2 at certain temperatures in the hydrogen storage alloy tank 31-Z shown in FIG. 2 are different from each other.

In this embodiment, the hydrogen storage alloy tanks 31-1, 31-2, and 31-3 have smaller heat capacities in that order. That is, among the three hydrogen-absorbing alloy tanks 31-1, 31-2, and 31-3, the hydrogen-absorbing alloy tank 31-1 has the smallest heat capacity, and the hydrogen-absorbing alloy tank 31-3 has the largest heat capacity. The difference in heat capacity between the hydrogen-absorbing alloy tanks 31-1 and 31-2 and the difference in heat capacity between the hydrogen-absorbing alloy tanks 31-2 and 31-3 are substantially equal to each other. Specifically, among the tanks 31-1, 31-2, and 31-3, the hydrogen storage alloy tank 31-1 has the smallest internal volume, and the hydrogen storage alloy tank 31-3 has the largest internal volume.

The hydrogen storage alloy tank 31-Z is connected to the electrolytic cell 21 via the hydrogen supply paths 221-Z, 221, and is connected to the second heat medium flow path 12 via the heat medium supply paths 235-Z, 235, It is connected to the first heat medium flow path 11 via heat medium supply paths 236-Z, 236. A pump 260 is provided in the heat medium supply path 235 . The heat medium supply path 235 on the downstream side of the pump 260 branches into three heat medium supply paths 235-1, 235-2 and 235-3. Valves 253-1, 253-2 and 253-3 are provided in the heat medium supply paths 235-1, 235-2 and 235-3, respectively. Intermediate water HC4 pumped by pump 260 is supplied as intermediate water (heat medium) HC5, distributed to intermediate water HC5-1, HC5-2, HC5-3, and stored in hydrogen storage alloy tanks 31-1, 31-2. , 31-3.

The heat medium supply path 236 branches into three heat medium supply paths 236-1, 236-2 and 236-3. Medium-temperature water HC5-1, HC5-2, and HC5-3 used for heating the hydrogen-absorbing alloy tanks 31-1, 31-2, and 31-3 are medium-temperature heat mediums HC6-1, HC6-2, HC6-3 is supplied to the heat medium supply paths 236-1, 236-2, and 236-3, and is combined with the heat medium HC6 and supplied to the first heat medium flow path 11 through the heat medium supply path 236.

The hydrogen storage alloy tanks 31-1, 31-2, and 31-3 are represented by the PCT diagram shown in FIG. Either one or both of the absorption and release of hydrogen H1-1, H1-2, H1-3 is performed according to the characteristics to be determined. The operations of the hydrogen storage alloy tanks 31-1, 31-2 and 31-3 will be described later.

A hydrogen supply path 222-Z is connected to the hydrogen storage alloy tank 31-Z. The three hydrogen supply channels 222-1, 222-2, 222-3 join one hydrogen supply channel 222. As shown in FIG. A valve 254 is provided in the hydrogen supply path 222 . Hydrogen H1-1, H1-2, and H1-3 released from the hydrogen storage alloy tanks 31-1, 31-2, and 31-3 are converted into hydrogen H2-1, H2-2, and H2-3, and are supplied to the hydrogen supply path 222. −1, 222 - 2 , 222 - 3 and the hydrogen supply line 222 to the fuel cell 4 . The branch position X may be provided with a configuration for switching the destination of the hydrogen H1, such as a three-way valve.

The fuel cell 4 generates electric power using hydrogen H2-1, H2-2, H2-3 obtained by discharging the hydrogen H1-1, H1-2, H1-3 stored in the hydrogen storage device 3. It is a device that emits generated electricity (generated electricity) E2, and includes a stack 41 and a heat exchanger . The stack 41 is a structure in which about 100 plate-like cells (not shown), which are minimum unit structures, are stacked in series and connected. A plate cell is a structure in which a separator, an anode, an electrolyte membrane, a cathode, and a separator are combined in this order. The separator, anode, electrolyte, and cathode materials are similar to known fuel cell stacks.

The stack 41 generates electricity using the supplied hydrogen H2-1, H2-2, H2-3 and releases the generated electricity E2. A hydrogen supply path 222 , an electricity supply path 212 , and heat medium supply paths 237 and 239 are connected to the stack 41 . The electricity E2 is supplied from the stack 41 through an electricity supply line 212 to a building or the like to which power is supplied by a power supply system (not shown).

The heat exchanger 42 is connected to the stack 41 via heat medium supply paths 237 and 239 , connected to the first heat medium flow path 11 via a heat medium supply path 238 , and connected to the first heat medium flow path 11 via a heat medium supply path 240 . 2 is connected to the heat medium flow path 12 . The heat exchanger 42 exchanges heat between medium-temperature water (heat medium) HC7 and low-temperature water (heat medium) HC8. The stack 41 dissipates heat when the electricity E2 is released as described above. The medium-temperature water HC7 warmed by the heat radiation of the stack 41 is supplied to the heat exchanger 42 through the heat medium supply path 237 . The low-temperature water HC8 is supplied from the first heat medium flow path 11 to the heat exchanger 42 through the heat medium supply path 238 . A valve 255 is provided in the heat medium supply path 238 .

The medium-temperature water HC7 cooled by heat exchange is returned to the stack 41 through the heat medium supply path 239 as the low-temperature water HC9. The low-temperature water HC8 warmed by heat exchange is supplied to the second heat medium flow path 12 through the heat medium supply path 240 as medium-temperature water HC10. The type of the heat exchanger 42 is, for example, a plate type, a fin tube type, or the like, but is not particularly limited as long as it can perform heat exchange between the medium temperature water HC7 and the low temperature water HC8.

The first heat medium flow path 11 and the second heat medium flow path 12 are connected via a heat medium connection path 241 . That is, the heat medium flowing through the first heat medium flow path 11 can be supplied to the second heat medium flow path 12 via the heat medium connection path 241 . A valve 256 is provided in the heat medium connection path 241 .

The heat medium flow path 202 is composed of a first heat medium flow path 11, a second heat medium flow path 12, heat medium supply paths 231 to 240, and a heat medium connection path 241. As shown in FIG. As will be described later in detail, the heat medium flow path 202 transfers the heat generated in the hydrogen production device 2 or the fuel cell 4 to the plurality of hydrogen storage alloy tanks 31-1, 31-2, and 31-3 as medium temperature water HC4 and HC10. configured to be supplied.

A control device (not shown) is configured to be able to control the supply or stop of hydrogen H1, H2 and electricity E1, E2 and the flow of each heat medium in the heat medium flow path 202, as will be described later in detail. For example, the control device is composed of a computer.
The control device records in a computer-readable recording medium a program for realizing the function of controlling the supply or stop of the hydrogen H1, H2 and the electricity E1, E2 and the flow of each heat medium in the heat medium flow path 202. It may also be realized by causing a computer system to read and execute the program recorded on this recording medium. Note that the above-mentioned "computer system" means an OS and hardware such as peripheral devices. A "computer-readable recording medium" means a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, and a storage device such as a hard disk incorporated in a computer system. Furthermore, a "computer-readable recording medium" dynamically retains a program for a short period of time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. may contain things. In addition, when the "computer-readable recording medium" dynamically retains the program for a short period of time as described above, like the volatile memory inside the computer system that serves as a server or client, It may also include those holding programs for a certain period of time. Further, the above-mentioned program may be for realizing a part of the above-mentioned functions, or may be a program capable of realizing the above-mentioned functions in combination with a program already recorded in the computer system, It may be implemented using a programmable logic device.

[Heat management method in hydrogen utilization system]
Next, a heat management method in a hydrogen utilization system according to one embodiment of the present invention will be described. The heat management method in the hydrogen utilization system of this embodiment controls three operation modes: <1> hydrogen production/occlusion mode, <2> hydrogen absorption/release stop mode, and <3> hydrogen release/fuel cell power generation mode. Managed by device. Management of each operation mode will be described below. 4 to 7 referred to in the following description show only the configuration in operation, and only the heat medium or hydrogen circulating in each supply path and each flow path in operation and their traveling directions is shown. In the initial state, each valve 251, 252, 253-1, 253-2, 253-3, 254, 255, 256 is closed.

<1> Hydrogen production/occlusion mode As shown in FIGS. 1 and 4, in this operation mode, a hydrogen production process and a first heat medium circulation process are performed.

In the hydrogen production process, until the total amount of hydrogen stored in the hydrogen-absorbing alloy tanks 31-1, 31-2, and 31-3 reaches at least a predetermined amount, the hydrogen-absorbing alloy tanks 31-1 with smaller heat capacities are sequentially used. The hydrogen H1 produced by the hydrogen producing device 2 is supplied to the hydrogen storage alloy tank. Specifically, the controller supplies electricity E<b>1 and pure water PW to the electrolytic cell 21 . The electrolytic cell 21 produces hydrogen H1 by electrolyzing the pure water PW. At this time, heat is generated from the electrolytic cell 21 to heat the pure water that has not reacted when the hydrogen H1 is produced. The hydrogen production device 2 recovers unreacted pure water, mixes it with the pure water PW, and raises the temperature of the pure water PW to a medium temperature of 40 to 50 degrees. After the temperature of the pure water PW rises, the unreacted pure water is supplied to the heat exchanger 22 as intermediate water HC1. Heat of about 30° C. is extracted from the intermediate water HC1 through the heat exchanger 22 .

Next, the valve 252 is opened, and the low-temperature water HC2 is supplied to the heat exchanger 22 from the building of the power supply system (not shown) or the like through the first heat medium flow path 11 and the heat medium supply line 232 . The low-temperature water HC2 is heated by the temperature of about 30 degrees taken out as described above. Heat exchange between the medium temperature water HC1 and the low temperature water HC2 in the heat exchanger 22 is repeated, the low temperature water HC3 is returned to the electrolytic cell 21, and the medium temperature water HC4 is supplied to the second heat medium flow path 12.

Next, valve 251 is opened. Here, C31-1, C31-2 and C31-3 are the maximum hydrogen storage amounts corresponding to the respective heat capacities of the hydrogen storage alloy tanks 31-1, 31-2 and 31-3. Also, let TC be a predetermined storage amount (storage amount) of hydrogen H1 to be stored in the hydrogen utilization system 200 . The storage amount TC is smaller than the total maximum hydrogen storage amount {(C31-1)+(C31-2)+(C31-3)} and is any of the maximum hydrogen storage amounts C31-1, C31-2, C31-3. bigger than In this operation mode, it is assumed that (C31-1)<TC<{(C31-1)+(C31-2)}.

The hydrogen H1 that has passed through the valve 251 is first sent to the hydrogen storage alloy tank 31-1 as hydrogen H1-1. The hydrogen storage alloy tank 31-1 stores an amount of hydrogen H1-1 substantially equal to the maximum hydrogen storage amount C31-1. Subsequently, the hydrogen H1 that has passed through the valve 251 is sent to the hydrogen storage alloy tank 31-2 as hydrogen H1-2. The hydrogen storage alloy tank 31-2 stores hydrogen H1-2 in the storage amount {TC-(C31-1)}. At this point, the total storage amount (total amount) of hydrogen H1-1 and H1-2 stored in the hydrogen storage alloy tanks 31-1 and 31-2 reaches a predetermined storage amount TC. The hydrogen storage alloy tank 31-3 is not used. Note that "until the total amount of hydrogen stored in the hydrogen storage alloy tanks 31-1, 31-2, and 31-3 reaches at least the predetermined storage amount TC" means that one or more unused hydrogen storage alloy tanks This means that the amount of storage of hydrogen H1-1 and H1-2 may be increased from the storage amount TC. Therefore, the hydrogen storage alloy tank 31-2 may store hydrogen H1-2 in the storage amount C31-2.

In the first heat medium circulation step, medium temperature water HC5 is circulated through all the hydrogen storage alloy tanks 31-1, 31-2 and 31-3. Specifically, the controller operates the pump 260 to pump the intermediate water HC4 into the heat medium supply path 235 as the intermediate water HC5. Open the valves 253-1, 253-2, 253-3 to distribute the intermediate water HC5 to the intermediate water HC5-1, HC5-2, HC5-3, the hydrogen storage alloy tanks 31-1, 31-2, 31- 3. While the hydrogen storage alloy tanks 31-1 and 31-2 store hydrogen H1-1 and H1-2 in the hydrogen production process, the storage reaction when the hydrogen storage alloy stores hydrogen H1-1 and H1-2. The heat of reaction generated by is recovered to warm medium-temperature water HC5-1 and HC5-2. The warmed intermediate water HC5-1, HC5-2 is circulated to all the hydrogen absorbing alloy tanks 31-1, 31-2, 31-3 including the unused hydrogen absorbing alloy tank 31-3 during hydrogen absorption. As a result, the temperature of each hydrogen storage alloy in the hydrogen storage alloy tanks 31-1, 31-2, 31-3 is maintained above a predetermined temperature at which hydrogen can be released.

<2> Hydrogen absorption/desorption stop mode In this operation mode, none of the hydrogen absorption alloy tanks 31-1, 31-2, and 31-3 are absorbing or releasing hydrogen. Therefore, the hydrogen storage alloy tanks 31-1, 31-2, 31-3 are naturally cooled according to the temperature difference between their own temperature and the environmental temperature of the air outside the tanks. A hydrogen-absorbing alloy tank with a large heat capacity is more difficult to cool than a hydrogen-absorbing alloy tank with a large heat capacity. That is, the hydrogen storage alloy tanks 31-3, 31-2, and 31-1 are difficult to cool in this order.

<3> Hydrogen Release/Fuel Cell Power Generation Mode As shown in FIGS. 1 and 5, in this operation mode, a hydrogen release process, a second heat medium circulation process, and a third heat medium circulation process are performed.

In the hydrogen releasing step, until the total amount of hydrogen released from the hydrogen absorbing alloy tanks 31-1, 31-2, and 31-3 reaches at least a predetermined release amount GC, the hydrogen absorbing alloy tanks 31-1 with smaller heat capacities are sequentially released. , releases the stored hydrogen H1-1, . . . Here, of the three hydrogen storage alloy tanks 31-1, 31-2, 31-3, the two hydrogen storage alloy tanks 31-1, 31-2 have maximum hydrogen storage amounts C31-1, C31-2 and It is assumed that approximately the same amount of hydrogen H1-1 and H1-2 are occluded. Specifically, the control device first causes the hydrogen storage alloy tank 31-1 to release, for example, 50% by mass or more and 90% by mass or less of hydrogen H1-1 as hydrogen H2-1 among the stored hydrogen H1-1. do. Subsequently, the hydrogen storage alloy tank 31-2 releases, for example, 50 mass % or more and 90 mass % or less of hydrogen H1-2 as hydrogen H2-2 from the stored hydrogen H1-2. The valve 254 is opened to combine the hydrogens H2-1 and H2-2 into hydrogen H2, which is supplied to the stack 41. When the total amount of released hydrogen H2-1, H2-2 reaches a predetermined release amount GC, the hydrogen releasing process is completed.

The stack 41 generates heat when emitting the electricity E2. Heat of about 30° C. is extracted from the intermediate water HC7 through the heat exchanger 42 . Subsequently, the valve 255 is opened to supply the low-temperature water HC8 to the heat exchanger 42 from the building of the power supply system (not shown) or the like through the first heat medium flow path 11 and the heat medium supply line 238 . The low-temperature water HC8 is heated by the temperature of about 30 degrees taken out as described above. Heat exchange between the medium temperature water HC7 and the low temperature water HC8 in the heat exchanger 42 is repeated, the low temperature water HC9 is returned to the stack 41, and the medium temperature water HC10 is supplied to the second heat medium flow path 12.

The second heat medium circulation process is performed slightly before the hydrogen release process until exhaust heat from the fuel cell 4 can be recovered. In the second heat medium circulation step, medium temperature water HC5 is circulated through all the hydrogen storage alloy tanks 31-1, 31-2 and 31-3. Specifically, the control device operates the pump 260 to pump the medium-temperature water HC10 to the heat-medium supply path 235 through the second heat-medium flow path 12 as medium-temperature water HC5. Open the valves 253-1, 253-2, 253-3 to distribute the intermediate water HC5 to the intermediate water HC5-1, HC5-2, HC5-3, the hydrogen storage alloy tanks 31-1, 31-2, 31- 3. While the hydrogen storage alloy tanks 31-1 and 31-2 are releasing hydrogen H2-1 and H2-2 in the hydrogen release process, the release reaction when the hydrogen storage alloy releases hydrogen H2-1 and H2-2. Heat is absorbed from medium water HC5-1 and HC5-2 by heat absorption at . At the same time, all the hydrogen storage alloy tanks 31-1, 31-2, 31-3, including the unused hydrogen storage alloy tank 31-3, are filled with medium temperature water HC5-1, HC5-2, HC5-. Cycle 3. Therefore, intermediate water HC5-3 containing heat from the hydrogen-absorbing alloy tank 31-3 circulates through the hydrogen-absorbing alloy tanks 31-1, 31-2, and 31-3, and heat is absorbed from the hydrogen-absorbing alloy tank 31-3. medium-temperature water HC5-1 and HC5-2. As a result, the temperature of each hydrogen-absorbing alloy in the hydrogen-absorbing alloy tanks 31-1, 31-2, 31-3 is maintained above a predetermined temperature at which hydrogen can be released.

As the supply of hydrogen H2-1 and H2-2 to the stack 41 progresses, the stack 41 starts releasing electricity E2, and exhaust heat from the fuel cell 4 can be recovered. After exhaust heat from the fuel cell 4 can be recovered, the second heat medium circulation process is shifted to the third heat medium circulation process.

As shown in FIG. 6, in the third heat medium circulation step, medium temperature water HC5-1, Circulate HC5-2. As a result, heat from the stack 41 is released as HC10, and quickly heats the hydrogen storage alloy tanks 31-1 and 31-2 via HC5-1 and HC5-2.

In the third heat medium circulation step, the heating of the hydrogen-absorbing alloy tanks 31-1 and 31-2 is accelerated by the heat from the stack 41, and the medium-temperature water HC5-1 and HC5-2 are heated. If the heat from the alloy tank 31-3 does not have to be used for heating the hydrogen-absorbing alloy tanks 31-1 and 31-2, a part of the heated intermediate water HC5-1 and HC5-2 or Intermediate water HC5-3 is used as heat medium HC6-1, HC6-2, HC6-3, and HC6, and passed through heat medium supply paths 236-1, 236-2, 236-3, and 236 to the first heat medium flow path 11. supply to The controller closes the valve 255 , opens the valve 256 , and supplies the heat medium HC 6 to the second heat medium flow path 12 through the heat medium connection path 241 . Furthermore, the heat medium HC6 is combined with the medium temperature water HC10 and pumped by the pump 260 into the heat medium supply path 235 as the medium temperature water HC5. As a result, the temperature of each hydrogen-absorbing alloy in the hydrogen-absorbing alloy tanks 31-1, 31-2, 31-3 is maintained above a predetermined temperature at which hydrogen can be released, and hydrogen H5-1, H5-2 can be released. Promoted.

The hydrogen utilization system 200 of the present embodiment described above includes the hydrogen production device 2 that produces hydrogen H1 using electricity E1 of renewable energy, and the hydrogen production device 2 that can store the hydrogen H1 produced by the hydrogen production device 2. Electric power is generated using a hydrogen storage device 3 provided with hydrogen storage alloy tanks 31-1, 31-2, and 31-3 having hydrogen storage alloys capable of releasing H1, and hydrogen H1 stored in the hydrogen storage device 3. , the fuel cell 4 that emits the electricity E2, and the heat medium flow path 202 configured to be able to supply the heat generated by the hydrogen production device 2 or the fuel cell 4 to the hydrogen absorbing alloy tanks 31-1, 31-2, 31-3. and a control device configured to be able to control the supply or stop of the hydrogen H1, H2 and the electricity E1, E2 and the flow of the heat medium in the heat medium flow path 202. Also, the heat capacities of the three hydrogen storage alloy tanks 31-1, 31-2, 31-3 are different from each other.

According to the hydrogen utilization system 200 of this embodiment, the hydrogen storage alloy tanks 31-1, 31-2, and 31-3 having different heat capacities are provided. The total heat capacity of the hydrogen storage alloy tank can be changed by utilizing some of the tanks 31-2 and 31-3. For example, when a plurality of hydrogen storage alloy tanks are heated and cooled by the heat from the hydrogen production device 2, the heat generated when the hydrogen storage alloy absorbs hydrogen H1, and the heat absorption when hydrogen H2 is released, all the hydrogen storage alloys By using the tanks 31-1, 31-2, and 31-3 as heating/cooling targets, the total heat capacity of the hydrogen absorbing alloy tank (hydrogen absorbing device) can be increased. When a plurality of hydrogen-absorbing alloy tanks are heated by heat from the fuel cell 4, only the hydrogen-absorbing alloy tanks 31-1 and 31-2 releasing hydrogen H2-1 and H2-2 are heated. Targeted, the total heat capacity of the hydrogen storage alloy tank can be minimized. As a result, the usage efficiency of the hydrogen utilization system 200 can be enhanced.

According to the hydrogen utilization system 200 of the present embodiment, the hydrogen H1 can be absorbed in order from the hydrogen absorbing alloy tank 31-1 having the smallest heat capacity, or the absorbed hydrogen H1 can be released. As a result, the total heat capacity of the unused hydrogen storage alloy tank can be increased when the hydrogen H1 is stored or released. Since the unused hydrogen-absorbing alloy tank functions as a heat storage medium, it becomes easier to maintain all the hydrogen-absorbing alloy tanks in a state capable of releasing hydrogen H2-1, H2-2, and H2-3, and the hydrogen utilization system 200 can be used more efficiently.

In the heat management method in the hydrogen utilization system 200 of the present embodiment, the total amount of hydrogen H1-1, H1-2, H1-3 stored in the hydrogen storage alloy tanks 31-1, 31-2, 31-3 is at least predetermined. The hydrogen produced by the hydrogen production apparatus 2 is supplied to the hydrogen storage alloy tanks 31-1 and 31-2 in order from the hydrogen storage alloy tank 31-1 with the smallest heat capacity until the storage amount TC of H1-1 and H1 is reached. -2, and a first heat medium circulation step of circulating medium-temperature water HC5-1, HC5-2, and HC5-3 in all the hydrogen-absorbing alloy tanks 31-1, 31-2, and 31-3. And prepare.

According to the heat management method in the hydrogen utilization system 200 of the present embodiment, the hydrogen H1 produced by the hydrogen producing device 2 is absorbed in order from the hydrogen absorbing alloy tank 31-1 with the smallest heat capacity in the hydrogen absorbing process. When the total amount of hydrogen stored in the hydrogen storage alloy tanks 31-1 and 31-2 reaches at least a predetermined hydrogen storage amount TC, the hydrogen storage step is completed. In the first heat medium circulation step, medium-temperature water HC5-1, HC5 is supplied to all the hydrogen-absorbing alloy tanks 31-1, 31-2, 31-3 including the unused hydrogen-absorbing alloy tank 31-3 in the hydrogen-absorbing step. -2, HC5-3 are circulated. At this time, it is possible to use the reaction heat (thermal heat) generated when hydrogen is absorbed in the hydrogen absorbing alloy tanks 31-1 and 31-2 to heat all the hydrogen absorbing alloy tanks 31-1, 31-2 and 31-3. can. Also, a hydrogen storage alloy tank 31-3 having a large heat capacity can be used as a heat storage medium. By these, the hydrogen storage alloys of all the hydrogen storage alloy tanks 31-1, 31-2, 31-3 are maintained above the temperature at which hydrogen H2-1, H2-2, H2-3 can be released, and hydrogen The usage efficiency of the utilization system 200 can be improved.

Further, in the heat management method in the hydrogen utilization system 200 of the present embodiment, the total amount of hydrogen H2-1, H2-2, H2-3 released from the hydrogen storage alloy tanks 31-1, 31-2, 31-3 is The stored hydrogen H1-1 and H1-2 are released to the fuel cell 4 as hydrogen H2-1 and H2-2 in order from the hydrogen storage alloy tank 31-1 with the smallest heat capacity until at least a predetermined release amount GC is reached. medium temperature water HC5-1, HC5-2, HC5-3 in all the hydrogen storage alloy tanks 31-1, 31-2, 31-3 until exhaust heat from the fuel cell 4 can be recovered. and the hydrogen storage alloy tanks 31-1 and 31-2 releasing hydrogen H2-1 and H2-2 after exhaust heat from the fuel cell 4 can be recovered. and a third heat medium circulation step of circulating medium-temperature water H5-1, H5-2 in the fuel cell 4.

According to the heat management method in the hydrogen utilization system 200 of the present embodiment, hydrogen H2-1 and H2-2 that have been occluded in the hydrogen-absorbing alloys are arranged in order from the hydrogen-absorbing alloy tank 31-1 with the smallest heat capacity in the hydrogen releasing process. is emitted. When the total amount of hydrogen released over the hydrogen storage alloy tanks 31-1 and 31-2 reaches at least a predetermined amount of released hydrogen GC, the hydrogen releasing step is completed. In the second heat medium circulation step, medium temperature HC5- 1, HC5-2 and HC5-3 are circulated. At this time, the heat absorption of the plurality of hydrogen-absorbing alloy tanks 31-1, 31-2 releasing hydrogen H2-1, H2-2 causes the heat absorption of all the hydrogen-absorbing alloy tanks 31-1, 31-2, 31-3. Although it contributes to cooling, heat is supplied from, for example, the hydrogen storage alloy tank 31-3, which has a large heat capacity and was not used when hydrogen was stored. This suppresses the temperature drop of the hydrogen storage alloy tanks 31-1, 31-2, 31-3 accompanying the release of hydrogen H2-1, H2-2. Furthermore, when the exhaust heat recovery from the fuel cell 4 becomes possible, the process shifts from the second heat medium circulation process to the third heat medium circulation process. In the third heat medium circulation step, the intermediate water H5-1, H5-2 is circulated only through the hydrogen storage alloy tanks 31-1, 31-2 releasing hydrogen H2-1, H2-2 and the fuel cell 4. . As a result, the total heat capacity of the hydrogen storage alloy tanks 31-1 and 31-2 to be heated by the heat from the fuel cell 4 is minimized, and the hydrogen storage alloy tanks 31-1 and 31-2 to be heated are minimized. can be quickly heated. Therefore, the usage efficiency of the hydrogen utilization system 200 can be enhanced.

Although preferred embodiments of the invention have been described in detail above, the invention is not limited to any particular embodiment. The invention can be modified within the scope of the invention described in the claims.

For example, in the above-described embodiment, the hydrogen storage device 3 of the hydrogen utilization system 200 includes three hydrogen storage alloy tanks 31-1, 31-2, and 31-3. The number of tanks is not limited to three. The storage amount TC should be smaller than the total maximum hydrogen storage amount of the plurality of hydrogen storage alloy tanks and larger than any of the maximum hydrogen storage amounts of the hydrogen storage alloy tanks. In the hydrogen utilization system 200, the maximum hydrogen storage amount C31-Z of each hydrogen storage alloy tank and the number of installed hydrogen storage alloy tanks are determined so as to satisfy the above relationship.

2 Hydrogen production device 3 Hydrogen storage device 4 Fuel cell 31-1, 31-2, 31-3 Hydrogen storage alloy tank 200 Hydrogen utilization system

Claims (2)

a hydrogen production device that produces hydrogen using surplus power of renewable energy;
a hydrogen storage device provided with a plurality of hydrogen storage alloy tanks capable of storing the hydrogen produced by the hydrogen production device and having the hydrogen storage alloy capable of releasing the stored hydrogen;
a fuel cell that generates power using the hydrogen stored in the hydrogen storage device and releases the generated power;
a heat medium flow path configured to supply heat generated in the hydrogen production device or the fuel cell to a plurality of the hydrogen-absorbing alloy tanks;
a control device configured to be capable of controlling the supply or stop of the hydrogen, the surplus power and the generated power, and the flow of the heat medium in the heat medium flow path;
A heat management method in a hydrogen utilization system in which the plurality of hydrogen storage alloy tanks have different heat capacities,
Hydrogen produced by the hydrogen production apparatus is poured into the hydrogen storage alloy tanks in order from the hydrogen storage alloy tanks with the smaller heat capacities until the total amount of hydrogen stored in the plurality of hydrogen storage alloy tanks reaches at least a predetermined storage amount. a hydrogen absorbing step of supplying and absorbing the hydrogen;
a first heat medium circulation step of circulating the heat medium through all the hydrogen storage alloy tanks;
comprising a
Thermal management method in hydrogen utilization system. a hydrogen production device that produces hydrogen using surplus power of renewable energy;
a hydrogen storage device provided with a plurality of hydrogen storage alloy tanks capable of storing the hydrogen produced by the hydrogen production device and having the hydrogen storage alloy capable of releasing the stored hydrogen;
a fuel cell that generates power using the hydrogen stored in the hydrogen storage device and releases the generated power;
a heat medium flow path configured to supply heat generated in the hydrogen production device or the fuel cell to a plurality of the hydrogen-absorbing alloy tanks;
a control device configured to be capable of controlling the supply or stop of the hydrogen, the surplus power and the generated power, and the flow of the heat medium in the heat medium flow path;
A heat management method in a hydrogen utilization system in which the plurality of hydrogen storage alloy tanks have different heat capacities,
Hydrogen release in which the stored hydrogen is released to the fuel cell in order from the hydrogen storage alloy tank with the smaller heat capacity until the total amount of hydrogen released from the plurality of hydrogen storage alloy tanks reaches at least a predetermined release amount. process and
a second heat medium circulation step of circulating the heat medium through all of the hydrogen-absorbing alloy tanks until exhaust heat from the fuel cell can be recovered;
a third heating medium circulation step of circulating the heating medium between the hydrogen-absorbing alloy tank that releases the hydrogen after exhaust heat from the fuel cell can be recovered and the fuel cell;
comprising a
Thermal management method in hydrogen utilization system.

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