A Multi-Phase CFD Study of a Liquid Slug Ingestion in a Reciprocating Compressor

The fluid handled by reciprocating compressors has to be strictly limited to gas and, under no circumstances, can there be a liquid fraction ingestion, as this event can cause the famous “liquid hammer effect” that can generate catastrophic failures. A study was conducted to evaluate the quantitative effects of the ingestion of a liquid slug into a reciprocating compressor cylinder with the goal of calculating the pressure distribution on the piston during such an event. The Multi-phase CFD ANSYS FSI software, utilized to simulate the behavior of a mixture of gaseous and liquid hydrocarbons during the delivery phase, has shown that the pressure inside the cylinder increases up to five times the normal pressure. This new approach can be helpful in the design stage or for root cause failure analysis of large compressors such as the ones utilized in the natural gas, refining, and LDPE industries.