Compression apparatus and filling station comprising such an apparatus

A fluid compression apparatus with multiple compression stages, comprising:

• a sealed enclosure and containing a bath of cryogenic fluid comprising a liquid phase, an upper part of the enclosure comprising a gas headspace;
• a first compression chamber;
• a second compression chamber;
• an intake system that communicates with the first compression chamber and is configured to allow the admission of fluid to be compressed into said first compression chamber;
• a transfer system that communicates with the first and the second compression chamber and is configured to allow the transfer of fluid from the first compression chamber to the second compression chamber;
• a mobile piston for ensuring the compression of the fluid in the first and second compression chambers;
• a discharge orifice that communicates with the second compression chamber and is configured to allow compressed fluid to leave through a discharge duct, the second compression chamber being delimited by a portion of a body of the mobile piston and a fixed wall of the apparatus, the mobile piston being mobile in a translational movement in a longitudinal direction;
• and a sealing system, wherein:
• the mobile piston comprises a tubular portion mounted around a fixed central guide, a terminal end of the fixed central guide forming the fixed wall delimiting part of the second compression chamber, the sealing system is formed between the fixed central guide and the mobile piston, in the longitudinal direction of translation of the mobile piston, the intake system is situated at a first end of the apparatus, the discharge orifice is situated at a second end of the apparatus, the transfer system is situated between the intake system and the discharge orifice, the first and second compression chambers are immersed in the liquid phase of the bath, and the intake system comprises one or more ports that either do or do not allow communication between the first compression chamber and the bath on the outside, depending on a longitudinal position of the mobile piston, wherein the mobile piston is actuated by a piston actuating mechanism, and wherein the intake system is located at the first end of the apparatus and the discharge duct and the piston actuating mechanism are located at the second end of the apparatus, which is an opposite end in the longitudinal direction.