Flexible hydrogen delivery mechanism for storage and recovery of hydrogen

Abstract

A conduit passage for use in transfer of hydrogen gas within a hydride system, including tubular members semi-permeable to hydrogen gas, permit hydrogen gas to pass through but not oxygen or other gases. The tubular members may comprise a flexible elastic polymeric material, such as polysulfone, polypropylene or polyethylene, including a central conduit passage, for providing hydrogen gas flow, the direction of the hydrogen flow depending on whether hydrogen is being absorbed or desorbed by the metal hydride. Simultaneously, the tube material, acting as a flexible spine, essentially fixes the hydride powder and prevents it from shifting about within the container, as well as being carried away in the hydrogen flow. Sections of the tubular member material may be interspersed throughout the hydride material to provide for peripheral hydrogen dispersion and to accommodate compressive stress forces that may develop as a result of the expansion of the hydride material during hydrogen absorption.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates generally to an apparatus for transferring, storing and recovering hydrogen from a hydridable material and more particularly to such an apparatus used for transferring hydrogen under pressure while simultaneously removing any gaseous impurities from the hydrogen stream before the hydriding step. [0003] 2. Background Art [0004] Hydrogen in the combinant form of water has long been employed in many chemical processes. Recent advances have permitted use of elemental hydrogen in gaseous form in physical processes, such as in heat transfer and electrical energy storage. For example, the fuel cell industry, among others, is continually developing new applications for hydrogen, including fuel cells and heat transfer applications. As a result there is a growing need to store hydrogen safely and conveniently in such applications. [0005] Hydrogen has been stored conventionally as a gas in steel cylinder...

AI Technical Summary

Benefits of technology

[0013] The tubular members act as a conduit for hydrogen gas; the direction of the hydrogen flow being a function of whether the hydrogen is being absorbed or desorbed by the metal hydride. Simultaneously, the tube material, acting as a flexible spine for the tube, essentially fixes the hydride powder and prevents it from shifting about within the container. In certain situations, the tube may also accommodate hydride material expansion, for example, when the hydride material becomes supersaturated with hydrogen and the expansion of the hydride material fills up the space within the tube.

Problems solved by technology

Both methods of storage require comparatively bulky storage containers that are often in need of maintenance.

In addition to their unwieldy size, such containers are inconvenient due to the high pressure required for gas storage in cylinders, which can contribute to the possibility of hydrogen gas leakage from the cylinders.

Although the weight of the metal hydride powder is a consideration, there may result a concomitant reduction in the weight of the container, since excessively large pressures will not be encountered, and thick container walls are not as significant.

One difficulty that has been investigated is high compressive stress due to the compaction of the powder and expansion thereof during hydride formation.

These stress forces are directed against the walls of the storage container and may damage the container itself or the associated internal assemblies unless provision is made to accommodate the impact of the forces.

Small, experimental cylinders of the aforedescribed type have indeed been found to open and / or burst when subjected to repetitive charging-discharging cycles, because of repeated and progressive structural stresses.

Additionally, it is undesirable for containers to lose their integrity since any hydrogen stream expelled out of a hydride container may be subject to combustion with possibly catastrophic results.

While the solution to the problem of hydride powder compaction described in the above-described patents are normally adequate to control excessive bulging and deformity of the container by absorbing the stress of metal hydride particles expanding as hydrogen is absorbed therein, the method has been found to be expensive and static from the ability to otherwise modify the operational efficiency and / or effectiveness of the hydrogen containers.

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