Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to an oxygen generator.
For patients suffering from, for ~xample, chronic lung or heart
dlsease, supplementary oxygen may be required to sustain life. This
oxygen may presen~ly be supplièd by oxygen bottles, liquid o~ygen tanks
or oxygen concentrators based on an adsorption process over a molecular
sieve.
Oxygen bottles and liquid oxygen tanks are both bulky and ex-
pensive and are not suitable for supplying oxygen safely in3 for example,
cars and private homes, as well as in hospitals.
Oxygen concentrators, based on an adsorptlon process over a
molecular sieve, of a practical si~e to be portable and are not capable
of supplying a sufficient concentration (i.e. purity~ of oxygen at a flow
rate above four litres which is requlred by some patients. Thus, oYygen
concentrators are not practical for supplying supplementary oxygen to
patients.
There is a need for a portable oxygen genera~or suitable for
supplying oxygPn safely in, for example, cars and private homes whlch is
neither too bulky or expenslve to be practical for such uses.
According to the present invention there is provided an o~ygen
generator, comprising:
(a~ an electrolytic genarator of oxygen and hydrogen Erom water, having
water inlet, a gaseous oxygen outlet, and a gaseous hydrogen outlet,
(b) a residual hydrogen and oxygen gas recombiner comprising a casing
having an inle~ connected to the gaseous oxygen outlet from the electro-
lytic generator, an outlet for substantially pure oxygen and an outletfor recombined oxygen and hydrogen, and a catalyst assembly in the casing
and comprislng at least one non-combustible support and an out~r, porous
membrane coating on the said at least one support and consisting of a
~rater repellent, hydrogen and oxygen gas permeable, high ~olecular
~elght, organlc, polymeric material and platinum crystallitea, with the
platinum crystallites dispersed in the polymeric m2terial,
(c) a primary hydrogen and oxygen gas recombiner comprising a caslng
having a hydrogen gas inlet connected to ~he gaseous hydrogen outlet from
tha electrolytic generator, an air lnlet, a recombined water outlet con-
mected to the water inlet of the electrolytic generator, and a vent to
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atmosphere, and a catalyst assembly in the casing and comprising at leastone non-combustible support and an Guter~ porous, membrane coating on the
said at least one support and consisting oE a water repellent, hydrogen
and oxygen gas permeable, high molecular weight~ organic, polymeric mate-
rial and platinum crystallites, with the platinum crystallites dispersedin the polymeric material, and
(d~ means for connecting a source of make-up water to the electrolytic
generator.
Preferably, a heat exchanger is connected to the vent of the
primary hydrogen and oxygen recombiner ~or, in operation, extracting use-
fNl heat from air componPnts whlch issue from the vent.
Preferably, the catalyst assembl-~ of -b~t- ~of the recombiners
is an ordered packed bed assembly comprising:
(a) corrugated, stainless steel wire mesh rolls forming the said at
least one non-combustible support,
(b) polytetrafluoroethylene forming the polymeric material, and
(c) hydrophobic silica particles with the platinum crystallites thereon
and dispersed in the polytetrafluoroethylene.
Preferably, the ordered packed bed assembly has a platinum con-
tent in the range 0.05 to 0.5 wt.% of the total weight of stainless steel
w:lre mesh, hydrophoblc silica and polytetrafluoroethylene~ a hydrophobic
s:Llica content in the range 1 to 5 wt.~ of the total weight of platinum,
stainless steel wire mesh and polytetrafluoroethylene, and a weight ratio
of 1:1 of polytetrafluoroethylene to platinum and hydrophobic silica con-
tent.
Preferably, the corrugations of each stainless steel wire mesh
roll are inclined at an angle in the range 30 to 45~ towards the axis o~
generation of that roll~
In the accompanying drawings which illustrate, by way of
example, an embodiment of the present invention,
Figure 1 is a flow diagram of an oxygen generator,
Figure 2 is a diagrammatic view of a residual hydrogen and
oxygen gas recombiner,
~ igure 3 is a diagrammatic view of a primary hydrogen and
oxygen gas recomblned, and
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Figure 4 is a perspective view of a catalyst packing in both of
the recombiners shown in Eigures 2 and 3.
Referring now to Figures 1 to 4, there is shown an oxygen
generator, comprising:
(a) an electrolytic generator 1 of oxygen and hydrogen from water, hav-
ing water inlet 2, a gas~ous oxygen outlet 4, and a gaseous hydrogen
Gutlet 6,
(b) a residual hydrogen and oxygen gas recombiner 8 comprising a casing
10 having an inlet pipe 12 connected to the gaseous oxygen outlet 4 from
the electrolytic generator 1, an outlet 14 for substantially pure oxygen
and an outlet 16 for recombined oxygen and hydrogen, and a catalyst
assembly 18 (Figure 2) in the casing 10 and comprising at least one non-
combustible support, such as the stainless steel mesh 20 (Figure 4), and
an outer, porous membrane coating on the said at least one support 20,
and consisting of a water repellent, hydrogen and oxygen gas permeable,
high molecular weight~ organic, polymeric material and platinum crystal-
lites with the platinum crystallites dispersed in the polymeric material,
(c) a primary hydrogen and oxygen gas recombiner 22 comprising a casing
24 having a hydrogen gas inlet pipe 26 connected to the gaseous hydrogen
outlet 6 from the electrolytic generatcr 1, an air inlet pipe 28, a
recombined water outlet 30 connected to the water inlet 2 of the electro-
lytic generator 1, and a vent 32 to atmosphere, and a catalyst assembly
34 (Fig. 3) in the casing 24 and comprising at least one non-combustible
support, such as the stainless steel mesh 20 (Eig. 4), and an outer,
porous, membrane coating on the said at least one support and consisting
of a water repellent, hydrogen and oxygen gas permeable, high ~olecular
weight, organic, polymeric material and platinum crystallites, with the
platinum crystallites dispersed in the polymeric material, and
(d) means, such as pipe 36, for connecting a source of make-up water to
the electrolytic generator 1.
The electrolytic generator 1 is preferably a polymer membrane,
electrolytic cell marketed by General Electric Company, Wilmington,
Massachusetts, U.S.A., as hydrogen generator systems having a solid
polymer electrolyte. Other pre~erred electrolytic generators are those
marketed by Electrolyser Inc., Toronto, Canada, and having an ~lk~lln~
electrolyte.
As shown in Figure 2, the residual hydrogen and oxygen gases
are distributed over the catalyst assembly 18 by the pipe 4 having a
coiled end 38 in the shape of a spiral and nozzles 40.
As shown in Figure 3, the primary hydrogen is dis~ributed over
the catalyst assembly 34 by the pipe 26 havlng a coiled end 42 in the
shape of a spiral and nozzles 44. The air is distributed over the cata-
lyst assembly 34 by the pipe 28 having a coiled end 46 in the shape of a
spiral and nozzles 48. It should be noted that the air no~zles 48 are
above the hydrogen gas nozzles 44 in order that any hydrogen gas that
tends to rise in the casing 24~ through hydrogen gas being lighter than
air, will become entrained by air from the air nozzles 48 and carried
downwardly thereby through the catalyst assembly 34. In some embodimerlts
of the present invention, heat from the air components with reduced oxy-
gen content that issue from the vent 32 is extracted as useful heat by
means of heat exchanger 50 connected to the vent 32. The heat in the air
components with reduced o~ygen content that lssue from vent 32 is the
exothermic heat from recombining the primary hydrogen with oxygen and may
be used as useful heat in, for example, a house.
A preferred form of the catalyst assembly of the type shown in
Figure 4 comprises a corrugated, stainless steel, wire mesh roll 20
having a coating thereon comprising a gas permeable, water repellent,
polytetrafluoroethylene coating and crystallites deposited on a hydro-
phobic silica (e.g. silicalite) partlcles, with the silica particles
dispersed in the polytetrafluoroethylene coating.
In tests that have been carried out to verify the present
invention, 2.8 litres/minute of oxygen in 99.7 wt.~ oxygen and 0.3 wt.%
hydrogen m~xture where generated using a General Electric Co. electro-
lytic generator 1 of the type mentioned above having an electrical input
o 15 amps at 115 volts and an electrolyte capacity of about 3 litres.
The total make-up water requirement through pipe 36 varied for a total of
up to 10 litres/day.
The residual hydrogen and oxygen gas recombiner 8 had an order-
ed, packed catalyst bed assembly 18 which was 5 cm diam~ x 5 ~m i~ height
and operated at near ambient temperature.
The primary hydrogen and oxygen gas recombiner 22 had an
ordered, packed catalyst bed assembly 10 cm diam. x 15 cm in height and
operated at a temperature in the range 150 to 200C.
It was found that by using, for both recombiners 8 and 22, an
ordered packed bed comprising a number of catalyst assemblies of the type
shown in Figure 4, each having:
(a) a platinum content in the range 0.05 to O.S wt.% of the total weight
of stainless steel wire mesh and silicalite and polytetrafluoroethylene,
(b) a silicalite content in the range 1 to 5 wt.% of the total weight of
platinum, stainless steel wire mesh and polytetraEluoroethylene, and
(c) a weight ratio of 1:1 of polytetrafluoroethylene to platinum and
silicalite content.
The oxygen from the outlet 14 of the residual hydrogen and
oxygen gas recombiner 8 issued at a temperature in the range 25 to 30C
and contained only water vapour and no detectable hydrogen to a detect-
able limit of 10 ppm. Oxygen supplied to a patient from outlet 14 would
have a purity greater than 99.99 volume %, excluding water vapol1r which
may be present and, if it i9, iS beneficial to the patient.
The primary hydrogen and oxygen gas recombiner 22 mixed 150
litres/min. of air with hydrogen and the recombined water issued from the
outlet 30 at ~ temperature in the range 10 to 35C. The hydrogen gas
recombining efficiency of the primary hydrogen and oxygen gas recombiner
22 was 99.99%0
Over 85% of the electrical energy consumed by the electroly-tic
cell was discharged into the environment as hot air. This hot air could
be utilized for heating, for example, a private home.
It was also found that by inclining the corrugations of the
stainless steel wire mesh 20 at an angle~ , inrllnlng upwardly towards
the axis XX of generation of the roll, in the range 30 to 45, better
mixing of gases was achieved in the packed, catalyst beds.
Examples of other suitable non-combustible support materials
for the catalyst assemblies are ceramics and stainless steel~
Examples of other suitable water repellent, hydrogen and oxygen
gas permeable~ hlgh molecular weight, organlc polymeric materials are
silicone compounds and styrene divinyl benzene copolymers.
7~C~
It should be noted that it i5 not possible to use an electro-
lytic generator 1 without the primary recombiner 22 because there is a
danger of explosion and so using an electrolytic generator 1 in this
manner would not pass the official safety requirements necessary for use
~n, for example, private homes or cars.
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