Fluent material handling – with receiver or receiver coacting mea – Processes – Filling dispensers
Reexamination Certificate
2001-08-31
2003-03-25
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Processes
Filling dispensers
C141S009000, C141S100000
Reexamination Certificate
active
06536485
ABSTRACT:
BACKGROUND OF THE INVENTION—TECHNICAL FIELD
My new hydrogen packaging technology classifies well with special gas packages or receptacles having abosorbents, adsorbents, or solvents. It more particularly concerns room temperature packaging of hydrogen in a receptacle containing a solvent comprising a special blend of hydrocarbons, of which at least one solvent component will be at or near its critical region state under the temperature and pressure conditions prescribed for practice of the invention.
Any method of room temperature hydrogen packaging, whether using highly compressed pure gas or my present invention, incurs less need for elaborate apparatus than does cryogenic storage. I consider a low cost container to be highly desirable in connection with providing a hydrogen source for electric vehicle fuel cells, or internal or external combustion engines, er for any hydrogen-consuming application where production of large numbers of portable, refillable containers is contemplated. Portability is not, however, essential in all possible application areas; for example, in certain load-levelling schemes for large-scale electrical power systems, storing hydrogen produced by electrolysis of water during periods of off-peak consumption would employ a large stationary container, operated on the same principles of smaller packaging systems embodying my invention.
BACKGROUND OF THE INVENTION—RELATED ART
Recent developments in supercritical fluids used as solvents seem to point somewhat generally in the direction of the invention. ‘SFE’, or ie., supercritical fluid extraction, is known to include mixing hydrogen and supercritical carbon dioxide for a variety of processes, such as hydrogenating oils, isomerization, polymerization, and conducting certain chemical syntheses. The enhancement of solvation accounting for increasing utilization of supercritical fluids in a solvent role has not been directed to enhanced dissolution of low molecular weight, highly volatile gases like hydrogen, however, but has mainly been directed to dissolving high molecular weight, low volatility solids and liquids like fats and oils. My packaging of hydrogen in solution with below-specified hydrocarbons is thought to exploit critical region phenomena in a manner unanticipated by any known proposal to admix a supercritical fluid and hydrogen.
On a terminological issue, attention is drawn to use by D. Dixon and K. Johnston in their reference entry for “SUPERCRITICAL FLUIDS”, KIRK-OTHMER
Encyclopedia of Chemical Technology,
of the term ‘compressed fluid’ to cover a co-extensive meaning I encompass hereinafter using ‘dense-phase fluid’ as a more recently fashionable term of jargon. The term ‘compressed fluid’ was used by Dixon and Johnston to encompass “either a supercritical fluid, a near-critical fluid, an expanded liquid, or a highly compressed gas, depending on temperature, pressure, and composition.” In disclosing my present invention, I employ ‘dense-phase fluid’ synonymously, as covering the same four forms of ‘compressed fluid’ mentioned by Dixon and Johnston. These forms of fluid do not correspond to sharply distinct states of matter, which are not found in the thermodynamic vicinity where critical region phenomena occur, causing many substances to manifest appreciable departures from classical expected behaviour of ideal liquids, ideal gases, ideal solutions or ideal mixtures. For example, where ordinary engineering practice commonly regards liquids as so negligibly compressible as to be practically incompressible, this is not the case for expanded liquids, which manifest both gas-like compressibility and diffusivity even though at liquid-like densities. In or near critical regions, fluid viscosities often are intermediate between what is usual for gases on the one hand and liquids on the other. It is thought that such concurrence in dense-phase fluids of both gas-like and liquid-like properties underlies their recognized utility for replacement of many traditional organic liquid solvents.
Rather than concern with use of solvents for extractive processes, for cleaning in general, or for thinning of viscous resins, glues, or paints to promote handling ease, the present invention concerns solvation as a technique for storing a solute gas, viz., dissolved hydrogen, the gas being thereby packaged for subsequent use in fuel cells or combustion apparatus, eg., engines, torches, and the like. There are at least two old familar examples of storing combustible gases as solutes in liquids: acetone has long been known to store dissolved acetylene; and propane condensed under pressure to the liquid state is known capable of storing dissolved methanee.
Early in 1990, in SAE Technical Paper 900586 entitled “Methane Solubility and Methane Storage in Suitable Liquid Hydrocarbon Mixtures”, I and B. D. Turnham reported our investigation into possible advantages of fueling combustion engines powering road vehicles with methane stored by dissolution in propane or other hydrocarbons, experimentally blending some mixtures intended to make improved methane packaging solvents. We reported that about 70% more methane could be packaged in a given tank filled with an appropriate mixture of liquid hydrocarbons than by storing the methane alone in the same tank at the same temperature and pressure. In some compositions we made and tested, reduced solvent mixture densities obtained by selective blending of different hydrocarbons produced effective methane-packaging solvents which made for lighter weight packaging than pure propane. Ethane containing blends in particular seemed to hold promise and in the SAE paper we stated: “In fact ethane itself with a critical temperature of 305 K was tested as a possible solvent but good data could not be obtained.”
Retrospectively, I consider that our data collection difficulties pertaining to some aspects of the methane storage research are attributable at least in part to critical region phenomena, eg., critical opalescence. The methane storage research in a sense predisposed me when subsequently turning to hydrogen storage to revisit ethane and other light hydrocarbons as possible storage media, ie., for making hydrogen packaging solvents.
In the vast accumulation of background data accessible to workers in the field are calculations of the mole fraction of dissolved hydrogen when in solution with condensed ethane at very high pressures and temperatures far below ethane's critical region, which R. J. Sadus has supplied in a Table in
High Pressure Phase Behaviour of Multicomponent Fluid Mixtures,
Elsevier Science Publishers, 1992. For example, the mole fraction of hydrogen of 0.728, equivalent to approximately 10% by weight, is listed for a binary ethane and hydrogen mixture at 175.2° K (ie., −97.8° C.) and a pressure of 233 MPa (ie., approximately 2,299 international standard atmospheres). Although 10% by weight of hydrogen in solution is better than the amount achieved by a number of known hydrogen storage methods utilizing packaging media, it is my opinion that the magnitudes of refrigeration and high pressure involved make the Sadus thermodynamic data merely citable as pertinent and of interest, rather than as disclosing a practical new method of hydrogen storage. Such extreme thermodynamic conditions require costly and elaborate apparatus and receptacles both to produce and to maintain.
BRIEF SUMMARY OF THE INVENTION
Important objects of the present hydrogen packaging method include: 1. a less energy-consuming manner of forcing a given amount of hydrogen at room temperature into the volume of a given receptacle than by forcing hydrogen alone into an empty receptacle; 2. a less energy consuming manner of packaging hydrogen than by its cryogenic liquifaction or other process requiring a great magnitude of refrigeration; 3. reduced packaging system weight by comparison to metal hydride type systems; 4. cheaper receptacle filling material to act as a hydrogen storing medium at less expense than costly to manufacture nanoscale particulate absorbents based on carbon allotroph
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