Process for reliquefying a methane-rich fraction

A process for reliquefying a methane-rich fraction, especially boil-off gas, is described. In this process, a) the methane-rich fraction (1) is compressed (C1) to a pressure at least 20% above the critical pressure of the fraction to be compressed, b) liquefied and subcooled (E2), c) decompressed (V...

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Bibliographische Detailangaben
Hauptverfasser: Bauer, Heinz, Franke, Hubert, Bub, Andreas
Format: Patent
Sprache:eng
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Zusammenfassung:A process for reliquefying a methane-rich fraction, especially boil-off gas, is described. In this process, a) the methane-rich fraction (1) is compressed (C1) to a pressure at least 20% above the critical pressure of the fraction to be compressed, b) liquefied and subcooled (E2), c) decompressed (V1) to a pressure between 5 and 20 bar, and d) separated into a gaseous nitrogen-rich (4) and a liquid nitrogen-depleted fraction (7), and e) the nitrogen-depleted fraction (7) is decompressed (V2) to a pressure between 1.1 and 2.0 bar, f) wherein the gaseous fraction (8) obtained is added to the methane-rich fraction (1) without being warmed up and compressed, and g) the liquid product fraction (9) which is obtained in the decompression of the low-nitrogen fraction has a nitrogen content of ≤ 1.5 mol%.