Fluent material handling – with receiver or receiver coacting mea – Processes – Plural materials
Reexamination Certificate
2003-09-04
2004-06-29
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Processes
Plural materials
C141S100000, C141S114000, C141S059000, C220S086200
Reexamination Certificate
active
06755219
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and an apparatus for supplying fuel for a hydrogen-operated vehicle.
BACKGROUND OF THE INVENTION
In the context of supplying fuel to a vehicle driven by means of a hydrogen fuel cell the hydrogen which is required for the fuel cell can be carried and stored in the vehicle in its pure form. As an alternative thereto the fuel can be produced by a chemical or catalytic reaction while the vehicle is actually in operation. That manner of proceeding affords advantages which are relevant in safety terms. A known procedure in that respect is for example the process which is referred to as the sodium borohydride reaction. In that procedure sodium borohydride (NaBH
4
) in aqueous solution is provided as the fuel. The sodium borohydride is fed to a catalyst unit which liberates pure hydrogen and sodium borate (NaBO
2
) in aqueous solution. The technically pure hydrogen can then be fed directly to a fuel cell connected on the downstream side of the catalyst unit. In the fuel cell hydrogen is reacted together with atmospheric oxygen to form water, more specifically with electrical energy being produced for a drive motor of the vehicle. The sodium borate which is produced in the catalytic reaction of the sodium borohydride can be recycled again by means of a suitable process to form sodium borohydride. It is therefore appropriate and desirable for the sodium borate which has been produced by the reaction to form the fuel for the fuel cell to be collected in a collecting container provided for that purpose in the vehicle.
It will be noted here that in the present specification the term reacted fuel may be used for brevity to denote the fuel component which is present after the catalytic reaction of the hydrogen donor that liberates the hydrogen for example for a fuel cell, and could thus also be referred to as post-reaction fuel.
If the usual volume of a fuel tank of a motor vehicle is employed for storing the fuel then the range of the vehicle, as measured on the basis of the available supply of fuel, is comparatively short in comparison with a motor vehicle fitted with an internal combustion engine burning a hydrocarbon fuel. In addition, when using the sodium borohydride catalysis procedure it is additionally necessary to provide a suitable storage volume for the reacted fuel, that is to say, as noted above, the sodium borate which has been produced after the catalytic reaction of the sodium borohydride. That storage volume will generally be to the detriment of the overall useful or payload volume of the vehicle.
So that the volume in the vehicle which is available for fuel storage can be utilised as effectively as possible, it is desirable for the unreacted fuel, that is to say the sodium borohydride, to be afforded in as concentrated a form as possible. Sodium borate precipitates out at levels of concentration of more than 20% by weight in aqueous solution so that it is appropriate for sodium borohydride to be fed to the catalyst unit at a concentration of 20% by weight in aqueous solution. If therefore sodium borohydride is to be stored in aqueous solution at a higher level of concentration then water should be added to the solution before it passes into the catalyst unit. For that purpose, connected upstream of the catalyst unit is a mixer which is operable to provide the sodium borohydrlde solution at the desired degree of dilution for the catalyst unit. In that situation the water which is fed to the mixer is taken from the waste gas flow from the fuel cell. Water vapor contained in the waste gas is condensed out in a condenser and fed to the mixer. When adopting that form of fuel preparation, for example when using 100 l of a 30% sodium borohydride solution as the unreacted fuel, about 115 l of 20% sodium borate solution is produced as the reacted fuel. In such a situation a particularly large volume is required for collecting and storing the reacted fuel. That is to the detriment either of the range of the vehicle or the useful or payload volume of the vehicle.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of supplying fuel for a vehicle operated by a hydrogen consumer such as a fuel cell, which makes it possible to achieve an adequate supply of fuel for a sufficient vehicle range while involving the smallest reasonable reduction in useful volume in the vehicle.
Another object of the invention is to provide a method of supplying fuel in a vehicle driven by a hydrogen consumer such as a fuel cell, which is designed to afford a reasonably sufficient range of operation for the vehicle without entailing excessive bulk.
Still another object of the present invention is to provide an apparatus for supplying a fuel cell with fuel in a vehicle driven by a motor operated by the fuel cell, which makes it possible to put an available fuel storage volume to a better and more viable use.
In accordance with the principles of the present invention in the method aspect the foregoing and other objects are attained by a method of supplying fuel for a motor vehicle comprising at least one oxygen consumer, for example a fuel cell, in which hydrogen is converted into electrical energy, the hydrogen being liberated by catalytic reaction of a hydrogen donor provided as the fuel, resulting in the production of recyclable reacted fuel. Unreacted fuel is taken from a first storage volume and at least one second storage volume which is separate from the first storage volume is filled with reacted fuel. The first storage volume which has become vacant by virtue of unreacted fuel being removed therefrom is at least partially additionally used for storage of the reacted fuel.
As will be seen in greater detail from the description hereinafter of preferred embodiments of the invention, the present invention is based on the notion of using at least a partial volume of the storage volume originally provided for the storage of unreacted fuel, after the removal of fuel therefrom, for the storage of reacted fuel. Such an operating procedure means that the volume required overall for storage of unreacted fuel and for storage of reacted fuel can be reduced to an optimum degree.
In accordance with a preferred feature of the method of the invention, in order to make optimum use of the structural space available in the context of a vehicle operated by for example a hydrogen fuel cell, it may be advantageous to use a plurality of spatially mutually separated containers or tanks as storage volumes for storing the fuel.
In accordance with another preferred feature of the method of the invention at least three series-connected containers are employed as storage volumes, wherein the unreacted fuel is taken from a first container, which can be referred to as a removal container insofar as the unreacted fuel is removed therefrom, wherein the removal container is fed with unreacted fuel from at least one storage container, wherein at least one collecting container is filled with reacted fuel and wherein the reacted fuel is transferred from the collecting container into the storage container or containers when the unreacted fuel has been completely withdrawn from the latter.
It will be easily appreciated that the removal container is not available for filling with reacted fuel as it is necessary to ensure that the vehicle can continue in operation until it is refilled with fuel. Furthermore the volume of the collecting container cannot be filled or refilled with unreacted fuel as reacted fuel is already produced Immediately after the commencement of operation of the vehicle and that reacted fuel must be suitably collected.
As will be described in greater detail hereinafter, it is desirable for the number and size of the containers which are to be provided to be optimised in regard to the amount of reacted fuel produced in relation to the amount of unreacted fuel involved. If about 115% of reacted fuel is produced for 100% of unreacted fuel the use of a total of five fuel containers has proven to be particularly advantageous in terms of ca
Douglas Steven O.
Grossman Tucker Perreault & Pfleger PLLC
Kautex Textron GmbH & Co. KG
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