Gas separation: apparatus – Solid sorbent apparatus – With indicating means
Reexamination Certificate
2001-06-13
2002-08-13
Simmons, David A. (Department: 1724)
Gas separation: apparatus
Solid sorbent apparatus
With indicating means
C096S126000, C096S133000, C206S000700, C502S416000
Reexamination Certificate
active
06432176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for storing compressed gas, in particular hydrogen, having at least one closed storage vessel which has at least one feed and discharge line for the compressed gas and, in its interior, a gas flow control system, the gas flow control system being connected to the feed and discharge line for the compressed gas, and in which a solid filling for storing the compressed gas is provided in the interior.
The storage of hydrogen in normal pressure vessels presents particularly significant difficulties if the maximum possible filling density based on the vessel volume is to be achieved.
2. Description of the Related Art
U.S. Pat. No. 4,964,524 discloses a device for storing compressed gas as described in the introduction, in which hydride-forming metal alloys form a fine particulate filling, having a storage capacity which is high with respect to the volume. However, this store has significant drawbacks, in particular on account of its high overall weight.
In recent times, there have been proposals to use what are known as carbon nanostructures to store gasses, in particular hydrogen. One such proposal can be found in WO 97/26082. The only statement made with regard to the technical design of storage device is that storage vessel is provided with a hydrogen storage bed. There are no indications as to the filling density of the nanostructure material.
In many applications in which stored hydrogen is to be used, it is imperative that it be possible to store the maximum possible quantity of gas with the smallest possible store volume and a small store weight (highest possible specific storage capacity). This requirement applies in particular to mobile applications, such as for example in hydrogen tanks for vehicles which are operated by fuel cells. Therefore, there is a need to further increase the storage capacity which it has hitherto been possible for storage devices for compressed gases, in particular hydrogen, to reach.
Furthermore, it is imperative, in particular when using storage devices as fuel tanks, for it to be possible to determine the current filling level of the storage device with compressed gas in a simple, inexpensive yet accurate way. The filling of mobile gas tanks is usually determined by determining the weight of the gas tank. With liquefied gas tanks, it is also possible to provide a strain gauge which is secured in linear fashion in the longitudinal direction of the gas tank on the outer wall of the gas tank, this gauge reacting to temperature changes in the region of the liquid level in the gas tank as a result of the formation of cold due to evaporation when the gas is removed, so that the current filling level can be approximately determined visually.
SUMMARY OF THE INVENTION
Working on the basis of the above-mentioned prior art, the invention is based on the object of providing a device for storing compressed gas, i.e. non-liquefied gas, in particular hydrogen, in which the drawbacks described in the prior art are avoided. In particular, the invention is to refine a device of the type described in the introduction in such a manner that its specific storage capacity is significantly increased and, at the same time, it is also possible to accurately determine the current filling quantity of the storage vessel.
This object is achieved by a device for storing compressed gas wherein the solid filling is a filling of carbon nanostructures which are joined to form larger cohesive conglomerates, and wherein at least one device for measuring the filling level of the compressed gas in the storage vessel is provided.
The basic idea of the invention is, inter alia, that the storage capacity for the compressed gas is increased by the solid filling, which comprises carbon nanostructures, in the storage vessel, since more nanostructure material can be introduced into the predetermined storage volume of the storage vessel by the formation of cohesive conglomerates than has hitherto been possible by simply introducing the carbon particles with a nanostructure which were originally produced. At least some of the conglomerates have a significantly higher density (apparent density) than a loose bed of the nanostructure material. The storage device according to the invention can be used for both stationary and mobile applications. In particular, the device according to the invention is suitable for storing gaseous fuels, such as for example hydrogen or the like.
Furthermore, the device for measuring the filling level makes it possible to measure the filling level of the stored medium. The measured filling level values can be presented by means of suitable display means, so that a user is informed in good time of when the storage vessel needs to be topped up with compressed gas.
It is advantageously possible to provide two or more storage vessels. The number of storage vessels used may be varied as desired depending on the particular application and demand. The individual storage vessels may advantageously be connected to one another, so that only a single feed or discharge line is required for the entire storage device.
Advantageously, the storage vessel may be designed as a pressure vessel, in particular as a pressure vessel for storing gases at a pressure of less than or equal to 150 bar. The invention is not restricted to any specific vessel geometries or vessel materials.
The storage vessel may, for example, be substantially cylindrical. A shape of this type is particularly suitable for storing compressed gases at high pressures. However, other vessel geometries are also possible. Particularly when using the storage device as a fuel tank for vehicles, it is not always possible—on account of the installation space available in the vehicle—to use a cylindrical vessel. Therefore, the cross section of the storage vessel may also, for example, be oval-shaped, flat or in the form of a storage cushion. The interior of the storage vessel may, by way of example, without implying any restriction, be circular in cross section.
The storage vessel may be of single-part or multipart design and/or of single-walled or multiwalled design. A specific design of the vessel can be selected individually depending on the particular requirement and application.
The vessel materials used may, for example, be suitable metals. However, it is also conceivable to produce the storage vessel from plastic, which may in particular be fiber-reinforced. The invention is not restricted to particular storage vessel materials. It is only important that the storage vessel overall be suitable for storing compressed gas at an operating pressure of preferably up to 150 bar.
In a further configuration, it is possible in each case to provide a separate feed line and discharge line for the compressed gas. A design of this nature may accelerate the charging and discharging operation of the storage vessel or storage vessels.
Preferably, at least one filter element, preferably a microfilter, is provided in the feed line and/or the discharge line for the compressed gas. A filter of this type reduces the undesirable discharge of particles of the solid filling from the storage vessel. Microfilters of this type preferably consist of hydrogen-resistant materials, for example of gas-permeable inorganic or organic polymer films, ceramic materials, inert gas-permeable sintered steels or the like.
In a further configuration, it is possible to provide a heating/cooling device for the interior of the storage vessel and/or the solid filling situated in the interior and/or the stored compressed gas. A heating/cooling device of this type can be used to set the optimum temperature for absorption during storage and desorption during discharging of the compressed gas in the carbon nanostructures in the storage vessel.
The heating/cooling device may advantageously have an inlet connection piece and/or outlet connection piece formed in the wall of the storage vessel for a heating/cooling medium. In this case, a passage or a line for the heating/coo
Klos Holger
Schütz Walter
Cohen & Pontani, Lieberman & Pavane
Lawrence Frank M.
Mannesmann AG
Simmons David A.
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