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Apparatus and method for compressing a cryogenic media

Apparatus and method for compressing a cryogenic media description/claims

This application claims the priority of International Application No. PCT/EP2006/004624, filed May 16, 2006, and German Patent Document No. 10 2005 024 888.8, filed May 31, 2005, the disclosures of which are expressly incorporated by reference herein.

The invention relates to a compressor, in particular a compressor for cryogenic media, preferably for liquid hydrogen, having a compressor compartment surrounded by a cylinder wall in which a compressor piston is moved linearly, an intake valve and a compression valve, both valves being arranged in the area of the lower end position of the compressor piston.

The term “cryogenic media” is understood below to refer to so-called deep cold fluids, in particular liquid hydrogen, liquefied natural gas, liquid nitrogen, liquid oxygen and other liquefied gases.

Compressors of this type are sufficiently well known from the state of the art. They all have in common the fact that the medium to be compressed is fed through a spring-loaded valve into a compressor compartment, where it is compressed and then removed from the compressor compartment via a spring-loaded compression valve.

FIG. 1 shows a lateral schematic sectional diagram of a generic compressor design belonging to the state of the art.

A compressor piston K′ is moved linearly back and forth and/or up and down within a compressor compartment R surrounded by a cylinder wall Z. The two reversing points of the compressor piston K′ are referred to below as the upper and lower end positions of the compressor piston K′.

An intake valve S and a compression valve D′ are arranged on the lower side of the cylinder compartment. During the intake stroke—during which the compressor piston K′ moves from its lower end position into its upper end position, i.e., from bottom to top in the present case—the liquid medium to be compressed enters the compressor compartment R through the intake valve S. During the following compression stroke—the compressor piston K′ moves from its upper end position back into its lower end position, which is shown in FIG. 1—the compressed medium is forced out of the compressor compartment R through the compression valve D′.

In liquid compression of a liquid cryogenic medium in particular, a gas phase G necessarily develops during compression. If the gas phase remains in the unavoidable dead space of the compressor compartment R after the compression stroke, then the gaseous medium will decompress inside the compressor compartment R during the following intake stroke. During this decompression, no new cryogenic medium can be drawn into the compressor compartment R through the intake valve S. Therefore, this results in a significant reduction in the delivery capacity of the compressor.

If the dead space were filled exclusively with liquid at the end of the compression stroke, then the unwanted decompression of the gaseous medium described above could be prevented. With all known compressor designs, the intake valve S and the compression valve D′ sit at the lower end of the cylinder housing Z. As a result, the liquid phase F is forced out of the compressor compartment R first by the compressor piston K′ through the compression valve D′ while a gas phase G necessarily remains in the remaining dead space.

It is fundamentally impossible to continue the movement of the compressor piston K′ as far as the bottom of the cylinder space Z and thereby reduce or “eliminate” the dead space. This is due to the optimization of the dead space of compressors. A certain dead space cannot be prevented due to the longitudinal expansion in cooling. If no dead space were provided, the valves could not even be integrated into the compressor.

However, the gas phase G, which necessarily remains in the dead space, expands after compression and thereby reduces the influx of “fresh” liquid to be compressed.

The object of the present invention is to provide a generic compressor, in particular a generic compressor for cryogenic media, with which the aforementioned disadvantages can be avoided.

To achieve this object, a generic compressor is provided and is characterized in that the compression valve is arranged laterally on the cylinder wall in the area of the lower end position of the compressor piston, and the head of the compressor piston has a conical shape.

FIG. 1 shows a lateral schematic sectional diagram of a generic compressor design belonging to the state of the art.

FIG. 2 shows a lateral schematic sectional diagram through one possible embodiment of the inventive compressor.

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