Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02403738 2007-11-01
Description
Title
= Electromagnetic Hydrogen Generation Method and System
Technical Field
= This invention relates to hydrogen generators, more
particularly to a hydrogen generator which uses
electromagnetic waves.
Background Art
= There are many instances where it would be desirable to be
able to provide a hydrogen generator which uses ammonia fuel
as a high-density hydrogen carrier.
= Compared to other candidate fuels for fuel-cell vehicles,
such as pure hydrogen (H2) and methanol (CH30H), ammonia
(NH3) has advantages in energy density (high) and fire safety
(non-flammable), among others. In addition, an ammonia fuel-
cell system has superior environmental performance to a
methanol fuel cell system because the exhaust contains not
CO2 (greenhouse gas) or CO (toxic gas) but N2 (inert gas).
Moreover, ammonia is naturally found (e.g., urine), and is a
household cleaning product (e.g., Windex (Trade Mark)).
Furthermore, ammonia is a liquid at modest pressures, not
unlike propane. Therefore, high hydrogen content is possible
in a relatively small volume. As for toxicity, the smell of
ammonia will prevent people from drinking it.
= Because ammonia (NH3) can be decomposed easily to yield
hydrogen (H2), it is a convenient portable source of atomic
hydrogen for welding. If an atom or molecule absorbs energy
from a beam of light (E = hv), it gains far more energy than
it ever could by other methods (e.g., from ordinary heating).
= A number of patents disclose hydrogen generators.
= U.S. Patent 6 245 309 discloses "Method and devices for
producing hydrogen by plasma reformer".
= U.S. Patent 6 274 093 discloses "Self-regulating hydrogen
generator".
= These prior art arrangements do not provide a hydrogen
generator which uses electromagnetic waves to generate
hydrogen (H2) from ammonia (NH3).
1
CA 02403738 2007-11-01
Description of the Invention
= It is a primary object of the invention to provide a hydrogen
generator which uses liquid anhydrous ammonia (NH3) as a
fuel.
= It is another object of the invention to provide a hydrogen
generator which dissociates ammonia (NH3) to generate
hydrogen (H2).
= It is another object of the invention to provide a hydrogen
generator which uses electromagnetic waves to crack ammonia
(NH3)=
= A hydrogen generation method comprises the steps of storing
anhydrous ammonia fuel in liquid phase under pressure,
vapourising the liquid ammonia into gaseous ammonia,
generating electromagnetic radiation, and dissociating
gaseous ammonia (NH3) into a mixture of gaseous nitrogen (N2)
and gaseous hydrogen (H2) by means of the electromagnetic
radiation according to formula: 2 NH3 -> N2 + 3 H2. A
hydrogen generator comprises an ammonia tank, an ammonia
vapouriser, an electromagnetic wave source, and an
electromagnetic dissociator. Preferably, the electromagnetic
wave source generates electromagnetic radiation in the vacuum
ultraviolet (VUV) region of the spectrum, at wavelengths
shorter than 254 nm. The electromagnetic wave source may be a
dielectric barrier discharge (DBD) lamp or an excimer lamp.
Brief Description of the Figures in the Drawings
= In drawings which illustrate embodiments of the invention:
o Figure 1 is a flow chart of one embodiment of an
electromagnetic hydrogen generation method according to
the invention;
o Figure 2 is a block diagram of one embodiment of an
electromagnetic hydrogen generation system according to
the invention; and
o Figure 3 is a sectional view of one embodiment of an
electromagnetic dissociator according to the invention.
Modes for Carrying Out the Invention
= According to the present invention shown in the flow chart of
Figure 1, a hydrogen generation method for feeding fuel cells
comprises the steps of storing anhydrous ammonia fuel 1-1 in
liquid phase under pressure, vapourising the liquid ammonia
2
CA 02403738 2007-11-01
1-2 into gaseous ammonia, generating electromagnetic
radiation 1-3, and dissociating gaseous ammonia (NH3) 1-4
into a mixture of gaseous nitrogen (N2) and gaseous hydrogen
(H2) by means of the electromagnetic radiation according to
formula: 2 NH3 -> N2 + 3 H2.
= The hydrogen generation method may further comprise the step
of removing residual ammonia (NH3) 1-5 from the mixture of
gaseous nitrogen (N2) and gaseous hydrogen (H2).
= The hydrogen generation method may further comprise the step
of removing nitrogen (N2) 1-6 from the mixture of gaseous
nitrogen (N2) and gaseous hydrogen (H2).
= Preferably, the electromagnetic radiation in the hydrogen
generation method is in the vacuum ultraviolet (VUV) region
of the spectrum, at wavelengths shorter than 254 nm.
= According to the present invention shown in the block diagram
of Figure 2, a hydrogen generation system for feeding fuel
cells comprises an ammonia tank 2-1 for storing anhydrous
ammonia fuel in liquid phase under pressure, an ammonia
vapouriser 2-2 for vapourising the liquid ammonia into
gaseous ammonia, an electromagnetic wave source 2-3 for
generating electromagnetic radiation, and an electromagnetic
dissociator 2-4 for dissociating gaseous ammonia (NH3) into a
mixture of gaseous nitrogen (N2) and gaseous hydrogen (H2) by
means of the electromagnetic radiation according to formula:
2 NH3 -> N2 + 3 H2.
= The hydrogen generation system may further comprise an
ammonia remover 2-5 for removing residual ammonia (NH3) from
the mixture of gaseous nitrogen (N2) and gaseous hydrogen
(H2)=
= The hydrogen generation system may further comprise a
nitrogen remover 2-6 for removing nitrogen (N2) from the
mixture of gaseous nitrogen (N2) and gaseous hydrogen (H2).
= The endothermic reaction of the ammonia vapouriser 2-2 may
provide cooling for the electromagnetic wave source of the
hydrogen generation system.
= Preferably, the electromagnetic wave source 2-3 generates
electromagnetic radiation in the vacuum ultraviolet (VUV)
region of the spectrum, at wavelengths shorter than 254 nm.
= The electromagnetic wave source 2-3 of the hydrogen
generation system may be a dielectric barrier discharge (DBD)
lamp with a noble gas such as xenon (Xe), krypton (Kr) or
3
CA 02403738 2007-11-01
argon (Ar). The electromagnetic wave source 2-3 of the
hydrogen generation system may be an excimer lamp with a
noble gas such as xenon (Xe), krypton (Kr) or argon (Ar).
= The electromagnetic wave source 2-3 of the hydrogen
generation system may comprise an electronic control gear
(ECG) for pulsed operation. The electromagnetic wave source
2-3 of the hydrogen generation system may comprise a radio-
frequency (RF) exciter for radio-frequency excitation.
= The electromagnetic wave source 2-3 of the hydrogen
generation system may be a high-efficiency ultraviolet light-
emitting diode (LED) made of semiconductors with wide band-
gap energy, such as gallium nitride (GaN) or aluminum nitride
(A1N). The electromagnetic wave source 2-3 of the hydrogen
generation system may be a high-efficiency ultraviolet
semiconductor laser diode (LD) made of semiconductors with
wide band-gap energy, such as gallium nitride (GaN) or
aluminum nitride (A1N).
= Figure 3 shows a sectional view of one embodiment of an
electromagnetic dissociator. The electromagnetic dissociator
comprises a flow-through fluid channel 3-1, an ultraviolet-
transparent window 3-4, and an electromagnetic wave source 3-
5.
= The flow-through fluid channel 3-1 has a middle portion, an
inner surface, an inlet port 3-2 for inflow of gaseous
ammonia (NH3), and an outlet port 3-3 for outflow of a
mixture of gaseous nitrogen (N2) and gaseous hydrogen (H2).
= The ultraviolet-transparent window 3-4 is securely attached
to the middle portion of the flow-through fluid channel 3-1.
= The electromagnetic wave source 3-5 generates electromagnetic
radiation in the ultraviolet (UV) region of the spectrum.
= The electromagnetic radiation from the electromagnetic wave
source 3-5 is capable of irradiating inside the flow-through
fluid channel 3-1 in order to dissociate gaseous ammonia
(NH3) into a mixture of gaseous nitrogen (N2) and gaseous
hydrogen (H2) according to formula: 2 NH3 -> N2 + 3 H2.
4
