Patent Application
20190252700
The present invention relates to hydrogen-producing devices. In particular, the invention relates to a hydrogen-producing device which is capable of starting up and continuing hydrogen production without receiving an energy supply from the outside.
Hydrogen tends to be costlier to store and transport compared to other fuels. Because of this, there is an intrinsic demand for on-site production of hydrogen, by installing a hydrogen-producing device adjacent to a device that uses hydrogen, or incorporating a hydrogen-producing device in equipment that uses hydrogen.
A known hydrogen production method consists of decomposing a hydrogen source such as ammonia, urea, or a hydrocarbon gas to produce hydrogen. A device used for decomposing a hydrogen source is usually called a reformer. A reformer needs to be supplied with energy from the outside on start-up, and a hydrogen-producing device is thus normally connected to, for example, an external power supply to supply energy to the reformer on start-up. However, in cases where the supply of energy from the outside was cut off or stopped, such as during a power outage or a natural disaster, it was difficult to start up the hydrogen-producing device until the external energy supply was restored.
Storage batteries are known means for supplying energy necessary for start-up of hydrogen-producing devices during emergencies. However, storage batteries having enough capacity to start up a hydrogen-producing device are large and expensive, and therefore a factor driving up the size and cost of the hydrogen-producing device as a whole. Further, when using a storage battery as an emergency energy storage means, repeated charging and discharging gradually depletes the capacity of the storage battery, leading to the risk that the required electric power could not be supplied after a certain time of use.
Various techniques have been proposed for starting up a hydrogen-producing device without supplying energy from the outside. Patent Document 1 discloses a technique for reducing power consumption on start-up of a hydrogen-producing device that includes a power supply for autonomous start-up. Patent Document 2 discloses a technique for ensuring that the stopping period of a hydrogen-producing device does not overlap with a power outage period based on power outage information obtained in advance.
Patent Document 1: Japanese Unexamined Patent Publication No. 2016-34881
Patent Document 2: Japanese Unexamined Patent Publication No. 2016-94328
Conventional hydrogen-producing devices with reformers could not be started up without being supplied with energy such as electric energy from the outside. This became a problem in that autonomous start-up was not possible during power outages or natural disasters. There was thus a need for technology that enables easy and certain start-up of a hydrogen-producing device even when energy cannot be supplied from the outside.
In order to overcome the aforementioned problem, the present invention provides a hydrogen-producing device capable of starting up without receiving an energy supply from the outside. The hydrogen-producing device according to the present invention includes an input unit which is connected to a hydrogen source and introduces a hydrogen-containing raw material, a reformer which decomposes the raw material introduced by the input unit to produce a hydrogen-containing gas, a hydrogen storage container which temporarily stores the hydrogen-containing gas produced by the reformer, a measurement unit which measures a storage amount of hydrogen-containing gas in the hydrogen storage container, a fuel battery that generates power using hydrogen-containing gas produced by the reformer and supplies power to the reformer, a fuel hydrogen supply path which supplies at least part of the hydrogen produced by the reformer to the fuel battery, an outside supply path which supplies part of the hydrogen produced by the reformer to the outside, and a control unit which receives measurement data from the measurement unit to control the amount of hydrogen-containing gas produced by the reformer, the storage amount of hydrogen-containing gas stored by the hydrogen storage container, and the amount of power generated by the fuel battery. The control unit of the hydrogen-producing device according to the present invention stores a threshold value of the measurement data corresponding to the minimum amount of hydrogen-containing gas necessary for start-up of the fuel battery, compares the received measurement data with the threshold value, and performs control to increase the storage amount of hydrogen-containing gas in the hydrogen storage container when the measurement data is below the threshold value. The fuel battery is characterized in that on start-up it uses the hydrogen stored in the hydrogen storage container to generate power and supplies power to the reformer.
The hydrogen-producing device according to the present invention includes a fuel battery (fuel cell) that uses a chemical reaction of hydrogen and oxygen to generate power. During normal operation, the hydrogen storage container that stores the hydrogen-containing gas supplied by the reformer always stores an amount of hydrogen-containing gas necessary for start-up of the fuel battery. When start-up of the hydrogen-producing device is required, power generation by the fuel battery is initiated by supplying the hydrogen-containing gas stored in the hydrogen storage container to the fuel battery. Further, hydrogen production by the reformer is initiated by supplying power from the fuel battery to the reformer. The fuel battery can use the hydrogen produced by the reformer to continue power generation and steadily supply the necessary energy to the reformer.
In the hydrogen-producing device according to the present invention, the output power of the fuel battery is preferably greater than the power consumed by the reformer. In addition, the operating temperature of the fuel battery of the hydrogen-producing device according to the present invention is preferably greater than or equal to the operating temperature of the reformer.
In the hydrogen-producing device according to the present invention, the reformer includes a plasma reactor for decomposing raw material and turning it into plasma, the plasma reactor having a raw material supply port and a hydrogen discharge port, a power supply for plasma generation that is supplied with power from the fuel battery, and a hydrogen separation unit that demarcates the hydrogen discharge port side of the plasma reactor. The hydrogen separation unit preferably separates hydrogen from the raw material turned into plasma in the plasma reactor, and transmits the hydrogen to the hydrogen discharge port side.
Further, the hydrogen separation unit of the hydrogen-producing device according to the present invention is preferably a hydrogen separation membrane connected to the power supply for plasma generation, which hydrogen separation membrane functions as a high-voltage electrode by being supplied with power and discharges electricity between the hydrogen separation membrane and a grounding electrode to turn the raw material into plasma.
In the hydrogen-producing device according to the present invention, the hydrogen-containing raw material is preferably ammonia or urea.
The present invention also provides an operating method of a hydrogen-producing device. The operating method of the hydrogen-producing device according to the present invention is applied to a hydrogen-producing device including an input unit which is connected to a hydrogen source and introduces a hydrogen-containing raw material, a reformer which decomposes the raw material introduced by the input unit to produce a hydrogen-containing gas, a hydrogen storage container which temporarily stores the hydrogen-containing gas produced by the reformer, a measurement unit which measures a storage amount of hydrogen-containing gas in the hydrogen storage container, a fuel battery that generates power using hydrogen-containing gas produced by the reformer and supplies power to the reformer, a fuel hydrogen supply path which supplies at least part of the hydrogen produced by the reformer to the fuel battery, an outside supply path which supplies part of the hydrogen produced by the reformer to the outside, and a control unit which receives measurement data from the measurement unit to control the amount of hydrogen-containing gas produced by the reformer, the storage amount of hydrogen-containing gas stored by the hydrogen storage container, and the amount of power generated by the fuel battery. In the operating method of the hydrogen-producing device according to the present invention, the control unit stores a threshold value of the measurement data corresponding to the minimum amount of hydrogen-containing gas necessary for start-up of the fuel battery, compares the received measurement data with the threshold value and performs control to increase the storage amount of hydrogen-containing gas in the hydrogen storage container when the measurement data is below the threshold value. The method is characterized in that it includes a step wherein the control unit, on start-up, supplies hydrogen from the hydrogen storage container to the fuel battery, a step wherein the fuel battery initiates power generation using the supplied hydrogen, a step wherein power generated by the fuel battery is supplied to the reformer, a step wherein the reformer produces hydrogen by decomposing the raw material and turning it into plasma, and a step wherein the produced hydrogen is supplied to the fuel battery to continue power generation.
The hydrogen-producing device according to the present invention is capable of starting up autonomously and producing hydrogen without receiving an energy supply such as electric energy from the outside. Moreover, the hydrogen-producing device according to the present invention is capable of starting up autonomously and producing hydrogen without a storage battery for start-up of the reformer.
Since the output power of the fuel battery of the hydrogen-producing device according to the present invention is greater than the power consumed by the reformer, the reformer can be reliably started up using only power supplied by the fuel battery. As a result, once the reformer has started up, it is possible for the reformer to provide a stable supply of hydrogen necessary for continued operation of the fuel battery, so that the fuel battery continues to generate power. In other words, the hydrogen-producing device according to the present invention is capable of autonomous operation in addition to autonomous start-up, thanks to the power supplied by the fuel battery that constitutes a part of the device.
Since the operating temperature of the fuel battery of the hydrogen-producing device according to the present invention is greater than or equal to the operating temperature of the reformer, heating means for the reformer and cooling means for the hydrogen-containing gas supplied from the reformer are not necessary. This allows for a simpler construction of the hydrogen-producing device as a whole, and allows for reduced power consumption. It also allows the system to be installed in a wider range of locations.
By configuring the reformer of the hydrogen-producing device according to the present invention as a plasma reformer including a plasma reactor, a power supply for plasma generation, and a hydrogen separation unit, it is possible to cause an electric discharge between the hydrogen separation membrane and a grounding electrode under room temperature and atmospheric pressure conditions to turn the hydrogen-containing raw material into plasma and thereby produce hydrogen-containing gas. Since the plasma reformer according to the present invention operates at room temperature, combining it with a solid polymer fuel battery having an operating temperature of 100° C. or less obviates the need for any heating or cooling means, which allows for a simpler construction of the system as a whole, and easier control of the reformer.
Since the hydrogen-producing device as a whole can have a simpler construction, and power consumption can be reduced, the hydrogen-producing device can be made cheaper and smaller.
Below is an itemized description of a preferred embodiment of the present invention.
(1) “Autonomous start-up” of the hydrogen-producing device according to the present invention means that the reformer and fuel battery can be started up without receiving electric energy or an equivalent energy supply from the outside, whereupon hydrogen production can be started and hydrogen supplied to the outside.
(2) The “hydrogen source” refers to a means for storing a hydrogen-containing raw material and supplying this substance as raw material to the hydrogen-producing device according to the present invention. More specifically, it refers to a storage container for a hydrogen-containing raw material, or a supply pipe in communication with this storage container. The substance stored or supplied by the hydrogen source is ammonia, urea, or a hydrocarbon gas such as methane or the like.
(3) The “reformer” refers to a device for producing hydrogen using a hydrogen-containing substance as raw material. The reformer according to a most preferred embodiment is a plasma reformer which includes a plasma reactor, a power supply for plasma generation, a hydrogen separation unit functioning as a high-voltage electrode, and a grounding electrode, the reformer turning the hydrogen-containing substance into plasma by causing an electric discharge between the electrodes, and allowing only hydrogen to pass through the hydrogen separation unit.
(4) As a reformer equivalent to a plasma reformer, a reformer which decomposes the hydrogen-containing substance using a catalyst to extract hydrogen, and a reformer combining a plasma reaction with a catalyst reaction, may be applied.
(5) The hydrogen-containing gas produced by the plasma reformer is a gas with hydrogen as its main constituent, and is particularly hydrogen of a high purity with a hydrogen concentration of 99.9% or higher.
(6) During normal operation, the control unit performs the following control:
An embodiment of the hydrogen-producing device according to the present invention is described below with reference to the drawings.
The hydrogen-producing device according to the present invention and the operating method of the device will now be described with reference to
The input unit 11 is connected to a hydrogen source 41 that stores and supplies a hydrogen-containing raw material, and introduces raw material received from the hydrogen source 41 into the reformer 12 via a raw material inlet path 29. The input unit 11 is preferably composed of a solenoid valve. The control unit 18 controls the degree of opening of the input unit 11 to control the amount of raw material introduced, and thereby controls the amount of hydrogen-containing gas produced by the reformer 12.
The reformer 12 decomposes a predetermined amount of raw material introduced via the raw material inlet path 29 to produce hydrogen-containing gas. The produced hydrogen-containing gas is temporarily stored in the hydrogen storage container 13 via a hydrogen supply path 21. The measurement unit 14 is connected to the hydrogen storage container 13, and measures the storage amount of hydrogen-containing gas in the hydrogen storage container 13. The measurement unit 14 is preferably a pressure gauge that measures the pressure inside the hydrogen storage container 13. The measured pressure is input into the control unit 18.
The hydrogen storage container 13 is provided with piping for outputting hydrogen in the form of the fuel hydrogen supply path 16 and the outside supply path 17. The fuel hydrogen supply path 16 in communication with the fuel battery 15 is provided with the control valve 19. The control unit 18 controls the degree of opening of the control valve 19 to control the amount of hydrogen-containing gas supplied to the fuel battery 15. The control unit 18 also controls the degree of opening of the control valve 20 provided to the outside supply path 17 to control the amount of hydrogen supplied to the outside and the storage amount of the hydrogen storage container 13. The control valves 19 and 20 are preferably composed of solenoid valves.
The fuel battery 15 uses hydrogen-containing gas supplied from the hydrogen storage container 13 and oxygen in air supplied from the oxygen supply means 43 to generate power. The fuel battery 15 is most preferably a solid polymer fuel battery with an operating temperature of 100° C. or less, and supplies generated power to the reformer 12 via the power supply path 30. The control unit 18 monitors the amount of power generated by the fuel battery 15 and controls the degree of opening of the control valve 19 and the amount of oxygen supplied from the oxygen supply means 43 in order to control a necessary amount of generated power. The oxygen supply means 43 is preferably an ordinary fan.
During normal operation, the control unit 18 performs the necessary control for achieving the two purposes of securing a required outside supply amount of hydrogen, and storing an amount of hydrogen-containing gas necessary for start-up of the fuel battery 15 in the hydrogen storage container 13. The control unit 18 stores the internal pressure in the hydrogen storage container 13 when it stores a minimum amount of hydrogen-containing gas necessary for start-up of the fuel battery 15 (hereinafter referred to as “start-up hydrogen amount”) as a threshold value. The control unit 18 then receives the measurement data from the measurement unit 14 and compares it with the threshold value. If it is determined based on the results of the comparison that the stored hydrogen-containing gas is below the start-up hydrogen amount, the control unit 18 controls the input unit 11 to increase the amount of raw material supplied to the reformer 12, thereby increasing the amount of hydrogen-containing gas produced by the reformer 12, so that the storage amount of the hydrogen storage container 13 becomes greater than or equal to the start-up hydrogen amount.
The stopping method of the hydrogen-producing device 1 will now be described with reference to
The start-up method of the hydrogen-producing device 1 will now be described with reference to
The reformer 12 preferably used in the present embodiment will now be described with reference to
The high-voltage electrode 25 is connected to a high-voltage pulsed power supply 22 which is connected to the fuel battery 15 via the power supply path 30, and is provided with a high voltage. O-rings 34 are fitted between the plasma reactor 23 and the supports 33 such that the hydrogen separation membrane 32 is arranged concentrically with the inner wall of the plasma reactor 23. As a result, a discharge space 24 in which a constant distance is maintained is formed between the inner wall of the plasma reactor 23 and the hydrogen separation membrane 32. In addition, on the inside of the hydrogen separation membrane 32, there is formed a sealed internal chamber 26 enclosed by the hydrogen separation membrane 32 and the supports 33. The grounding electrode 27 is arranged concentrically with the plasma reactor 23 and the hydrogen separation membrane 32. In the present embodiment, the most suitable raw material supplied from the hydrogen source 41 via the input unit 11 and the raw material inlet path 29 is ammonia gas. This ammonia gas is supplied to the discharge space 24 of the reformer 12.
The hydrogen separation membrane 32 and the grounding electrode 27 face each other, and the plasma reactor 23 made of quartz is arranged between them, so that the plasma reactor 23 acts as a dielectric, which allows for a dielectric barrier discharge to be generated by applying a high voltage to the high-voltage electrode 25 in the form of the hydrogen separation membrane 32. The power supply 22 that applies the high voltage to the high-voltage electrode 25 applies a voltage with an extremely short retention time of 10 μs.
Production of hydrogen using the reformer 12 is carried out by supplying ammonia gas to the discharge space at a predetermined flow rate, generating a dielectric barrier discharge between high-voltage electrode 25 in the form of the hydrogen separation membrane 32 and the grounding electrode 27, and generating atmospheric pressure non-equilibrium plasma of ammonia in the discharge space 24. The hydrogen gas generated from the atmospheric pressure non-equilibrium plasma of ammonia is separated by passing through the hydrogen separation membrane 32 and moving into the internal chamber 26. The hydrogen generated from the atmospheric pressure non-equilibrium plasma of ammonia is adsorbed by the hydrogen separation membrane 32 in the form of hydrogen atoms, which scatter as they pass through the hydrogen separation membrane 32, after which they recombine into hydrogen molecules and move into the internal chamber 26. In this way, only hydrogen is separated. The hydrogen that has moved into the internal chamber 26 is stored in the hydrogen storage container 13 via the hydrogen supply path 21 as high-purity hydrogen with a hydrogen concentration of 99.9% or higher.
Below is shown an Example of autonomous start-up of the hydrogen-producing device 1 including the reformer 12 and the fuel battery 15. The present Example employs as the fuel battery 15 a solid polymer fuel battery having a start-up hydrogen amount of 50 liters (0.05 m3) at 0.1 MPa (1 standard atmosphere).
In the present Example, a pressure gauge is employed as the measurement unit 14 for measuring the storage amount of the hydrogen-containing gas in the hydrogen storage container 13. The control unit 18 stores a threshold value of pressure corresponding to the amount of hydrogen-containing gas necessary for start-up of the fuel battery 15. During hydrogen production, the control unit 18 monitors the measured results of the measurement unit 14, and performs feedback control of the amount of hydrogen-containing gas produced by the reformer 12 and the storage amount of the hydrogen storage container 13 using the results of a comparison of the stored threshold value with the measured results, and constantly stores hydrogen-containing gas corresponding to the hydrogen amount of 50 liters necessary for start-up of the fuel battery 15 in the hydrogen storage container 13.
The reformer 12 of the present Example is a plasma reformer which includes a plasma reactor 23, a high-voltage electrode 25 housed within the plasma reactor 23, and a grounding electrode 27 arranged in contact with the outside of the plasma reactor 23. An example of the relationship between the power consumed by the reformer 12 and the amount of hydrogen produced is shown in Table 1 and
As shown in Table 1 and
An example of the relationship between the amount of hydrogen supplied to the fuel battery 15 and the amount of power generated is shown in Table 2 and
The power generated by the fuel battery 15 is supplied to the reformer 12 via the power supply path 30. Receiving the power, the reformer 12 starts up, and the high-voltage pulsed power supply 22 applies a high voltage to the high-voltage electrode 25 to generate a dielectric barrier discharge between the high-voltage electrode 25 in the form of the hydrogen separation membrane 32 and the grounding electrode 27, thereby initiating hydrogen production. As is clear from the relationship shown in
The configuration and operation method of the hydrogen-producing device 1 described in the present Example may be altered as necessary. For example, in a variant of the reformer 12, the cylindrical hydrogen separation membrane 32 housed in the plasma reactor 23 may be grounded, and an electrode arranged in contact with the outside of the plasma reactor 23 may be connected to the high-voltage pulsed power supply 22. At this time, the hydrogen separation membrane 32 acts as the grounding electrode, and a dielectric barrier discharge can be generated like in the Example. Even in this case, the hydrogen separation membrane 32 is exposed to the plasma, and hydrogen can thus be separated.
In the present embodiment, an example was described in which the hydrogen storage container 13 and the control valves 19 and 20 were arranged in separate locations, but the control valves 19 and 20 can also be arranged at the outlets of the hydrogen supply paths, in one piece with the hydrogen storage container 13. In addition, the measurement unit 14 that measures the storage amount of the hydrogen storage container 13 may be another measurement device apart from a pressure gauge. For example, a weight sensor that measures the weight of the hydrogen may be used. The wiring and current voltage control means of the power supply path 30 for supplying power from the fuel battery 15 to the reformer 12 can also be altered depending on the overall arrangement and function of the device as a whole.
1 hydrogen-producing device
11 input unit
12 reformer
13 hydrogen storage container
14 measurement unit
15 fuel battery
16 fuel hydrogen supply path
17 outside supply path
18 control unit
19, 20 control valve
21 hydrogen supply path
22 high-voltage pulsed power supply
23 plasma reactor
24 discharge space
25 high-voltage electrode
27 grounding electrode
29 raw material inlet path
30 power supply path
32 hydrogen separation membrane
33 support
41 hydrogen source
42 external load
43 oxygen supply means
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-224912 | Nov 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/037162 | 10/13/2017 | WO | 00 |
