Information
-
Patent Grant
-
6524464
-
Patent Number
6,524,464
-
Date Filed
Wednesday, April 25, 200123 years ago
-
Date Issued
Tuesday, February 25, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Nguyen; Nam
- Nicolas; Wesley A.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 205 335
- 205 628
- 205 633
- 205 637
- 422 22
- 204 2281
- 204 2283
- 204 2285
-
International Classifications
-
Abstract
A fan flow sensor for a hydrogen generating proton exchange member electrolysis cell includes a switching device and a sail slideably disposed on the switching device. The sail is configured to actuate the switching device in response to an airflow from a fan. The switching device may be actuatable in response to a magnet disposed on the sail.
Description
BACKGROUND
Electrochemical cells are energy conversion devices that are usually classified as either electrolysis cells or fuel cells. Proton exchange membrane electrolysis cells function as hydrogen generators by electrolytically decomposing water to produce hydrogen and oxygen gases. The hydrogen gas is then removed and used as a fuel. Referring to
FIG. 1
, a section of an anode feed electrolysis cell of the related art is shown generally at
10
and is hereinafter referred to as “cell
10
.” Reactant water
12
is fed into cell
10
at an oxygen electrode (anode)
14
to form oxygen gas
16
, electrons, and hydrogen ions (protons). The chemical reaction is facilitated by the positive terminal of a power source
18
connected to anode
14
and a negative terminal of power source
18
connected to a hydrogen electrode (cathode)
20
. Oxygen gas
16
and a first portion
22
of the water are discharged from cell
10
, while the protons and a second portion
24
of the water migrate across a proton exchange membrane
26
to cathode
20
. At cathode
20
, hydrogen gas
28
is formed and is removed for use as a fuel. Second portion
24
of water, which is entrained with hydrogen gas, is also removed from cathode
20
. The removal of hydrogen is generally effectuated through a gas delivery line.
Cell
10
includes a number of individual cells (not shown) arranged in a stack with reactant water
12
being directed through the cells via input and output conduits formed within the stack structure. The cells within the stack are sequentially arranged, and each one includes a membrane electrode assembly defined by a proton exchange membrane disposed between a cathode portion and an anode portion. The cathode portion, anode portion, or both may be gas diffusion electrodes that facilitate gas diffusion to the proton exchange membrane. Each membrane electrode assembly is supported on both sides by screen packs within flow fields. The screen packs facilitate fluid movement and membrane hydration and provide mechanical support for the membrane electrode assembly.
Power to the electrolysis cell is interrupted when, after sensing a condition such as a pressure variation in the gas delivery line, a control unit signals an electrical source that drives a reference voltage applied across a potentiometer to an extreme value. In such a system, the control unit is directly dependent upon the detection of a mass leak from the gas delivery line. Depending upon the preselected conditions of the system, when the power interruption capability is dependent upon the detection of a mass leak, a delay between the time that the leak occurs and the time at which the system is shut down may be experienced. Such systems do not provide early detection of potential problems but instead simply react to signals indicative of problems currently existing in the operation of the cell.
SUMMARY
A fan flow sensor for a hydrogen generating proton exchange member electrolysis cell is disclosed herein. The fan flow sensor includes a switching device and a sail slideably disposed on the switching device. The sail is configured to actuate the switching device in response to an airflow from a fan.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic representation of an anode feed electrolysis cell of the related art.
FIG. 2
is a schematic representation of a gas generating apparatus into which an electrolysis cell may be incorporated.
FIG. 3
is an exploded perspective view of a ventilation system of a gas generating apparatus.
FIG. 4
is a perspective view of a ventilation system of a gas generating apparatus.
FIGS. 5A and 5B
are exploded sectional views of sail/collar assemblies.
FIG. 6
is an alternate configuration of a sail/collar assembly.
FIGS. 7A and 7B
are alternate configurations of retainers disposed on spindles.
DETAILED DESCRIPTION
Referring to
FIG. 2
, an exemplary embodiment of a gas generating apparatus incorporating a proton exchange membrane electrolysis cell is shown generally at
30
and is hereinafter referred to as “generator
30
.” Generator
30
is suitable for generating hydrogen for use in gas chromatography, as a fuel, and for various other applications. It is to be understood that while the inventive improvements described below are described in relation to an electrolysis cell, the improvements are generally applicable to both electrolysis and fuel cells. Furthermore, although the description and figures are directed to the production of hydrogen and oxygen gas by the electrolysis of water, the apparatus is applicable to the generation of other gases from other reactant materials.
Generator
30
includes a water-fed electrolysis cell capable of generating gas from reactant water and is operatively coupled to a control system. Suitable reactant water is deionized distilled water and is continuously supplied from a water source
32
having a level indicator
34
and a drain
36
operatively included therewith. The reactant water is pumped through a pump
38
into an electrolysis cell stack
40
. Cell stack
40
comprises a plurality of cells similar to cell
10
described above with reference to
FIG. 1
encapsulated within sealed structures (not shown). The reactant water is received by manifolds or other types of conduits (not shown) that are in fluid communication with the cell components. An electrical source
42
is connected across the anodes and cathodes of each cell within cell stack
40
to allow the water to disassociate.
Oxygen and water exit cell stack
40
via a common stream and are ultimately returned to water source
32
, whereby the water is recycled and the oxygen is vented to the atmosphere. The hydrogen stream, which contains water, exits cell stack
40
and is fed to a phase separation tank, which is a hydrogen/water separation apparatus
44
, hereinafter referred to as “separator
44
,” where the gas and liquid phases are separated. This hydrogen stream has a pressure that is generally about 250 pounds per square inch (psi), but which may be anywhere from about 1 psi up to about 6000 psi. Some water is removed from the hydrogen stream at separator
44
. The exiting hydrogen gas (having a lower water content than the hydrogen stream to separator
44
) is further dried at
46
, for example by a diffuser, a pressure swing absorber, or a dessicant. The removed water with trace amounts of hydrogen entrained therein may be returned to water source
32
through a low pressure hydrogen separator
48
. Low pressure hydrogen separator
48
allows hydrogen to escape from the water stream due to the reduced pressure, and also recycles water to water source
32
at a lower pressure than the water exiting separator
44
. Separator
44
may also include a release
50
, which may be a relief valve, to rapidly purge hydrogen to a hydrogen vent
52
when the pressure or pressure differential exceeds a preselected limit.
Pure hydrogen from dryer
46
is fed to a hydrogen storage
54
. Valves
56
,
58
may be provided at various points on the system lines and may be configured to release hydrogen to vent
52
under certain conditions. Furthermore, a check valve
60
is provided that prevents the backflow of hydrogen to dryer
46
and separator
44
.
A ventilation system, shown generally at
62
, is provided to assist in venting system gases when necessary. Ventilation system
62
comprises a fan portion that continually purges the air in the enclosure of generator
30
. An airflow switch is mounted on the fan portion and is configured to interrupt the power to cell stack
40
in the event of a failure in the fan portion, thereby halting the production of hydrogen gas.
A hydrogen output sensor
64
is incorporated into generator
30
. Hydrogen output sensor
64
may be a pressure transducer that converts the gas pressure within the hydrogen line to a voltage or current value for measurement. However, hydrogen output sensor
64
can be any suitable output sensor other than a pressure transducer, including, but not limited to, a flow rate sensor, a mass flow sensor, or any other quantitative sensing device. Hydrogen output sensor
64
is interfaced with a control unit
66
, which is capable of converting the voltage or current value into a pressure reading. Furthermore, a display means (not shown) may be disposed in operable communication with hydrogen output sensor
64
to provide a reading of the pressure, for example, at the location of hydrogen output sensor
64
on the hydrogen line. Control unit
66
may be any suitable gas output controller, such as an analog circuit or a digital microprocessor.
Water source
32
provides the fuel for generator
30
by supplying the reactant water to the system. The reactant water utilized by generator
30
is stored in water source
32
and is fed by gravity or pumped through a supply line into cell stack
40
. The supply line is preferably clear unplasticized polyvinyl chloride (PVC) hose. An electrical conductivity sensor
67
may be disposed within the supply line to monitor the electrical potential of the water, thereby determining its purity and ensuring its adequacy for use in generator
30
.
Referring now to
FIGS. 3 and 4
, ventilation system
62
is shown in greater detail. Ventilation system
62
comprises a fan portion, shown generally at
68
, and a fan flow sensor portion, shown generally at
70
, disposed in operable communication with fan portion
68
. Fan portion
68
and fan flow sensor portion
70
are mounted within the generator with a bracket
72
. Fasteners
74
extending through bracket
72
enable fan portion
68
to be secured to bracket
72
. Fan portion
68
comprises an impeller (not shown) rotatably mounted within a housing
76
and driven by a motor (not shown), which may be a 12 volt DC motor. The impeller provides ventilation within the enclosure of the generator via a continual purge of air at a rate such that if the full production of hydrogen were to leak into the enclosure, the hydrogen would be vented outside the enclosure and diluted to a very low concentration.
Fan flow sensor portion
70
comprises an airflow switch, shown generally at
78
, and a sail/collar assembly, shown generally at
80
, in operable communication with airflow switch
78
. Sail/collar assembly
80
is configured to receive airflow from fan portion
68
. Airflow switch
78
is defined by a switching device mounted in a spindle
82
extending from an upper surface of a base member
84
. Sail/collar assembly
80
is defined by a substantially planar sail
85
having a collar
86
extending either from an upper surface of sail
85
as shown or through the upper surface and a lower surface of sail
85
. Collar
86
is received over spindle
82
such that slideable communication is maintained therebetween. A retainer
88
is disposed at an upper end of spindle
82
distal from base member
84
.
In
FIGS. 5A and 5B
, fan flow sensor portion
70
, particularly airflow switch
78
and sail/collar assembly
80
, are shown in greater detail. Airflow switch
78
is configured to function independent from the delivery line pressure of the hydrogen gas. In airflow switch
78
, spindle
82
is fixedly mounted to base member
84
at a lower end thereof such that spindle
82
extends substantially perpendicularly from the upper surface of base member
84
. Alternately, spindle
82
and base member
84
may be cast as a unitary piece. An opening
90
is formed within spindle
82
and extends therethrough to enable communication to be maintained between the switching device inside spindle
82
and a ventilation system control unit (not shown) remotely located from spindle
82
. The switching device is securely disposed within spindle
82
with a potting material
92
. Potting material
92
provides a relief to stresses associated with the operation of airflow switch
78
and is generally a solidified material such as an epoxy. An adhesive (not shown) may be applied to a lower surface of base member
84
to facilitate the attachment of airflow switch
78
to a hub
79
of the fan portion.
The switching device is a reed switch and is shown generally at
94
. Reed switch
94
includes two separate flexible magnetic reeds
95
a,
95
b
disposed adjacent to each other within an enclosure
96
. Enclosure
96
is centered within potting material
92
. The flexibility of reeds
95
a,
95
b
enables reeds
95
a,
95
b
to be magnetically biased together such that contact can be intermittently made therebetween and maintained upon the magnetic actuation of reed switch
94
, which is effectuated by the placement of a magnet
98
in close proximity to reeds
95
a,
95
b.
In
FIG. 5A
, magnet
98
is shown as a bar magnet disposed longitudinally along the length of collar
86
. In
FIG. 5B
, magnet
98
is shown as a ring magnet disposed around collar
86
. In either configuration, lead wires
100
extend from each reed
95
a,
95
b
through potting material
92
and through opening
90
to provide electronic communication between reed switch
94
and the ventilation system control unit.
With respect to sail/collar assembly
80
, collar
86
functions as a guide member to provide for the translational motion of sail
85
along spindle
82
. Collar
86
is configured to be received over spindle
82
such that sail/collar assembly
80
is slideably disposed on spindle
82
. Regardless of whether magnet
98
is a bar magnet, as is shown in
FIG. 5A
, or a ring magnet, as is shown in
FIG. 5B
, magnet
98
is disposed on the outer surface of collar
86
; alternately, magnet
98
may be insert-molded directly into collar
86
. Magnet
98
is generally fabricated from a rare earth element such as neodymium. Both collar
86
and spindle
82
are radially dimensioned relative to each other to facilitate such slideable motion with a minimum amount of resistance generated by the contact of the outer surface of spindle
82
and the inner surface of collar
86
. Both collar
86
and spindle
82
are likewise axially dimensioned relative to each other such that collar
86
can axially translate the length of spindle
82
to a point where reed switch
94
is unaffected by magnet
98
.
Sail
85
is fixedly mounted to a lower end of collar
86
. Alternately, sail
85
can be integrally formed with collar
86
, e.g., collar
86
can be formed or molded with sail
85
such that sail/collar assembly
80
is a unitary piece. The dimensions of sail
85
substantially correspond with the dimensions of the opening in the fan portion through which airflow is generated by the rotation of the impeller. In particular, because the shape of the opening in the fan portion is generally circular, sail
85
is generally circular. Materials that may be used for the construction of sail
85
(and also for the construction of collar
86
) include, but are not limited to, titanium, aluminum, high density polypropylene, polytetrafluoroethylene, nylon, and MYLAR.
Retainer
88
is a ring-shaped element dimensioned to be positioned over the upper end of spindle
82
and fixedly attached thereto. Retainer
88
prevents the axial translation of sail/collar assembly
80
beyond the upper end of spindle
82
and, more particularly, prevents the removal of sail/collar assembly
80
from spindle
82
altogether.
Referring now to
FIG. 6
, another configuration of a sail/collar assembly is shown generally at
180
. Sail/collar assembly
180
comprises a collar
186
and an associated magnet
198
similar to those described with reference to
FIGS. 3
,
4
,
5
A, and
5
B. Sail/collar assembly
180
further comprises a sail, shown generally at
185
, having a deflective surface
187
disposed about the periphery of sail
185
. Deflective surface
187
is dimensioned to be angled away from a flat planar surface
189
of sail
185
at an angle α, which is generally between about five and ten degrees. By incorporating deflective surface
187
into the architecture of sail
185
, sail/collar assembly
180
can experience additional lift as a result of airflow from the fan portion.
Referring now to
FIGS. 7A and 7B
, additional configurations of airflow switches are shown. In an airflow switch shown generally at
178
in
FIG. 7A
, the retainer (as illustrated at
88
in
FIGS. 3
,
4
,
5
A, and
5
B) can be reconfigured to define tabs
188
fixedly disposed on and extending laterally from the upper end of a spindle
182
. Tabs
188
comprise protrusions extending normally from the surface of a spindle
182
to prevent the axial translation of a sail/collar assembly (not shown) beyond the upper end of spindle
182
. Tabs
188
are, furthermore, flexible to allow the sail/collar assembly to be “snapped” onto spindle
182
. Although two tabs
188
are illustrated, any number of tabs
188
can be disposed peripherally about the cross section of the upper end of spindle
182
to retain the sail/collar assembly thereon.
In an airflow switch shown generally at
278
in
FIG. 7B
, a retainer
288
is configured as a plug having a lip
289
and a plug portion
291
. Once the sail/collar assembly (not shown) is inserted onto a spindle
282
, plug portion
291
is inserted into an upper open end of a spindle
282
. Lip
289
is dimensioned to overhang the outer perimeter of spindle
282
, thereby retaining the sail/collar assembly thereon.
The operation of fan flow sensor portion
70
is described with reference to
FIGS. 3
,
5
A, and
5
B. The slideable communication maintained between sail/collar assembly
80
and spindle
82
provides for the actuation of airflow switch
78
. Airflow switch
78
is electronically configured to interrupt the flow of electrical current to the cell stack in the event that the airflow generated by the impeller of fan portion
68
is impeded to any degree as a result of operational difficulties. At startup of the generator, sail/collar assembly
80
rests on spindle
82
adjacent base member
84
. Magnet
98
provides communication between reeds
95
a,
95
b
of reed switch
94
by causing reeds
95
a,
95
b
to flex and remain in contact with each other. The contact maintained between reeds
95
a,
95
b
closes a circuit, thereby causing electronic communication to be maintained between reed switch
94
and the ventilation system control unit through lead wires
100
. Upon rotation of the impeller, airflow is generated through fan portion
68
, which causes sail
85
to slide via collar
86
up spindle
82
and lift away from base member
84
. Upon proper functioning of fan portion
68
, the lift experienced by sail
85
causes magnet
98
to be removed from the proximity of reed switch
94
. Reeds
95
a,
95
b
then relax and separate, thereby interrupting the continuity of the circuit and removing the signal to the cell stack that causes the interruption of power.
In order for the generator to be shut down during its operation, only ventilation system
62
needs to malfunction. By configuring the system such that the interruption of power thereto is dependent upon the proper functioning of ventilation system
62
instead of the pressure delivery line, the cell stack can be shut down upon obstruction of fan portion
68
(or a similar problem) prior to any leakages of hydrogen gas. The cell stack and all of its associated components except for ventilation system
62
may, therefore, be in functioning order during the operation of the generator. Nevertheless, because ventilation system
62
operates independent of the delivery line pressure, malfunction or failure of either fan portion
68
or airflow switch
78
will close the circuit and cause a signal to be sent to the electrical source to interrupt the flow of electrical current to the cell stack, thereby shutting down operation of the generator.
While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.
Claims
- 1. A method of controlling the operation of an electrolysis cell said method comprising:generating an airflow at a sail of a ventilation system disposed in operable communication with a switch, wherein said switch is in operable communication with said electrolysis cell; translating said sail in response to said airflow; actuating said switch in response to said translating of said sail; and breaking the continuity of an electrical communication between said switch and said electrolysis cell upon impeding of said airflow to discontinue operation of said electrolysis cell.
- 2. The method of claim 1, wherein said breaking of the continuity further comprises interrupting a signal to said electrolysis cell.
- 3. The method of claim 2, wherein said breaking of the continuity of the electrical communication further comprises separating reeds of a magnetically actuatable reed switch.
- 4. The method of claim 1, wherein said translating of said sail further comprises causing said sail to slide along a collar in response to said airflow.
US Referenced Citations (6)
Number |
Name |
Date |
Kind |
4788389 |
Okazaki |
Nov 1988 |
A |
5736016 |
Allen |
Apr 1998 |
A |
5783060 |
La Riviere et al. |
Jul 1998 |
A |
5980726 |
Moulthrop, Jr. et al. |
Nov 1999 |
A |
6022459 |
Briggs |
Feb 2000 |
A |
6033549 |
Peinecke et al. |
Mar 2000 |
A |