Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1999-11-15
2001-10-16
Gorgos, Kathryn (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S228600, C205S637000
Reexamination Certificate
active
06303009
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems and methods of generating hydrogen gas from water using an electrolysis reaction. More particularly, the present invention is related to systems and methods of generating hydrogen gas where an electrolysis reaction is induced across a proton exchange membrane.
2. Description of the Prior Art
For many years, it has been known that water can be separated into hydrogen gas and oxygen gas using an electrolysis reaction. Over the years there have been many production of hydrogen gas, such devices are commonly known as hydrogen generators.
In some of the more efficient prior art hydrogen generators, an electrolysis reaction is induced across a proton exchange membrane. To increase the output pressure of hydrogen, a pressure differential is commonly produced across the proton exchange membrane. However, proton exchange membranes are thin and are easily damaged. Proton exchange membranes by themselves cannot withstand any significant pressure differential without rupturing. Accordingly, the proton exchange membranes in many prior art devices are reinforced with wire mesh screens that support the proton exchange membranes. During the operation of such prior art hydrogen generators, the proton exchange membrane is biased against a wire mesh screen by a pressure on the hydrogen side of the membrane. The pressure on the membrane is greater on the hydrogen side than it is on the oxygen side, which is usually at atmospheric pressure. The output pressure of the hydrogen gas is equal to the pressure that is being applied to hydrogen side of the proton exchange membrane. The wire mesh screen typically has a 70% to 80% opening this results in the pressure on the screen to be 3.3 to 5 times higher than the output pressure of the hydrogen gas. This causes the proton exchange membrane to wear rapidly. This is due to the large forces developed at the points of contact with the screen and the openings in the screen, where the proton exchange membrane is being stretched between the supporting elements of the screen. After a relatively short operational life, holes begin to appear in the proton exchange membrane at points where the membrane contacts the wire mesh screen. Once the holes add up to a predetermined minimum area, for a given size hydrogen generator, the proton exchange membrane is incapable of producing the hydrogen required and the hydrogen generator ceases to function adequately.
In prior art designs, a single hydrogen electrolysis cell typically has more than 15 separate parts not counting nuts, bolts and washers. These parts include as many as eight titanium screens, titanium supporting plates and rubber like sections that must be glued together. The net result is that the hydrogen generating devices using proton exchange membranes are expensive, complex, difficult to assembly and unreliable. These designs also have significant pressure variations across the proton exchange membrane causing accelerated wear and decreased performance of the hydrogen generator.
In prior art hydrogen generators, certain manufacturers developed designs that stack multiple proton exchange membranes atop one another. In such designs, each of the proton exchange membranes is supported by its own set of wire mesh screens. Although holes do develop in each of the proton exchange membranes, the life of the hydrogen generator is prolonged by the redundant positioning of the proton exchange membranes and therefore the increased capacity of the initial hydrogen generator. Hydrogen generators that use multiple proton exchange membranes, however, are significantly more expensive due to the cost of the multiple proton exchange membranes and the complexity of the design. This stacking of proton exchange membranes significantly reduces the manufacturability and reliability of such hydrogen generating devices.
Another problem associated with prior art hydrogen generators is that the electrolysis reaction tends to warm the water being used in the electrolysis reaction. This in part is due to the oxidation of the titanium that is used in the electrolysis chamber, which increases the resistance in the current path. The excess heat generated is in close proximity to the proton exchange membrane. As the water warms, the vapor pressure of the water increases. The water vapor contaminates the hydrogen gas being produced. The hydrogen gas in many cases must therefore be processed through a separate purification procedure before the hydrogen gas can be used. The problem of heated water is particularly prevalent in hydrogen generator designs that use multiple proton exchange membranes. In such prior art hydrogen generators, each proton exchange membrane chamber tends to be thermally isolated. It is therefore difficult to remove heat from the internal chambers and reduce the water vapor pressure to acceptable levels. The proton exchange membrane also degrades more rapidly at higher temperatures thereby further reducing the useful life of the hydrogen generator.
A need therefore exists in the art for a hydrogen generator that operates with a proton exchange membrane that does not have a pressure differential across the proton exchange membrane, thereby eliminating the production of wear abrasions in the membrane. A need also exists for a hydrogen generator that is capable of using only a single high efficiency proton exchange membrane and that operates at reduced water temperatures and can be actively cooled if necessary and at the same time have a high output gas pressure with little differential strain on the proton exchange membrane. These types of cells can then be stacked, connecting the gas outputs of each cell in parallel to achieve the desired hydrogen flow. These needs are met by the present invention system and method as is described and claimed below.
SUMMARY OF THE INVENTION
The present invention is a hydrogen generator system for generating hydrogen gas from water. The system includes a proton exchange membrane across which an electrolysis reaction is induced, thereby producing hydrogen gas on a first side of the proton exchange membrane and oxygen gas on a second side of the proton exchange membrane. The gas produced by the system is regulated by a unique high efficiency, high speed constant current power supply that controls the flow of current across the proton exchange membrane. This power supply both monitors and controls the current through the proton exchange membrane. In addition the voltage drop across the proton exchange membrane or membranes are also monitored if more than one membrane is placed in series.
A hydrogen gas chamber receives the hydrogen gas produced on the first side of the proton exchange membrane. Similarly, an oxygen gas chamber receives the oxygen gas produced on the second side of the proton exchange membrane. The proton exchange membrane is uniquely mounted so that there is a notable increase in gas produced per unit area, as compared to prior art systems.
A pressure regulator mechanism is provided for maintaining a predetermined pressure differential between the hydrogen gas chamber and the oxygen gas chamber. By maintaining a pressure differential of near zero between the gas chambers, the proton exchange membrane is not differentially stressed and both the life and performance of the hydrogen generator are significantly improved. In addition, because of the good thermal connection to the anode and cathode in the proton exchange membrane the operating temperature of the membrane is kept cool. This also increases the reliability and life of the hydrogen generator.
REFERENCES:
patent: 4822469 (1989-04-01), Shimomura et al.
patent: 5037518 (1991-08-01), Young et al.
patent: 5733422 (1998-03-01), Lin
patent: 6033549 (2000-03-01), Peinecke et al.
patent: 6126797 (2000-10-01), Sato et al.
Gorgos Kathryn
LaMorte & Associates P.C.
Nicolas Wesley A.
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