A METHOD AND A DEVICE FOR CHANGING THE COMPRESSION RATIO OF A RECIPROCATING COMPRESSOR

A device (4) [and a method] for changing the compression ratio of a reciprocating compressor (3) comprising a plurality of compression chambers (2i) pneumatically connected between an inlet port (40) and an outlet port (50), wherein a plurality of commutation valves (V) is provided for changing the number of compression steps, said valves arranged to switch [caused to switch] from a first to a second open/closed state combination, or vice-versa, wherein a lower number and a higher number, and vice-versa, respectively, of the compression chambers (2i) comprises chambers serially connected to one another, so that a gas to be compressed (8) is subjected to a number of compression steps that increases when switching from the first to the second combination, and decreases when switching in the opposite direction. Moreover, a control unit (60) is provided that is configured to [steps are provided of] receiving pressure signals (451,46N) upstream and downstream of the reciprocating compressor (3), respectively, to [of] computing the corresponding pressure ratios, to [of] generating opening/closing control signals (47) responsive to the pressure ratios, and to [and of] transferring the control signals to actuators of the commutation valves (V). In an application, the gas to be compressed (8) is withdrawn from a closed space (80), typically a compression facility of a gas pipeline, from which the gas has to be evacuated from an initial pressure (Psc,0) to a final pressure (P*) and, once compressed, is sent into a reception space (90), typically the gas pipeline itself, which is at a working pressure (Pe) that remains substantially unchanged during the evacuation. By the invention, it is possible to drastically reduce the emissions of harmful/valuable gas, which are currently released or burnt into the environment, during such evacuation operations. La présente invention concerne un dispositif (4) [et un procédé] permettant de modifier le taux de compression d'un compresseur alternatif (3) comprenant une pluralité de chambres de compression (2i) reliées de manière pneumatique entre un orifice d'entrée (40) et un orifice de sortie (50), une pluralité de soupapes de commutation (V) étant fournie pour modifier le nombre d'étapes de compression, lesdites soupapes étant agencées pour commuter [être amenées à commuter] d'une première à une seconde combinaison d'état ouvert/fermé, ou vice-versa, un nombre inférieur et un nombre supérieur, et vice-versa, respectivement, des