59353 - Wet Gas Formation and Carryover in Compressor Suction Equipment 

In gas processing, boosting, and gathering applications, gas-liquid separator equipment (typically referred to as a scrubber) is placed upstream of each reciprocating compressor stage to remove water and hydrocarbon condensates. However, field experience indicates that liquids can still be carried over from the scrubber. Furthermore, even if the gas leaving the scrubber is dry (i.e., a saturated vapor), pressure and heat losses in compressor pulsation bottles and nozzles may be sufficient to lead to condensation. When these liquids are ingested into the reciprocating compressor, machinery failures, some of which are severe, can result. While it is generally understood that liquid carryover and condensation can occur, it is less clear how the multiphase fluid moves through equipment downstream of the scrubber.

In this paper, mechanisms responsible for liquid formation and carryover into reciprocating compressors are explored. First, the effects of liquid ingestion on reciprocating compressors reported in the open literature are reviewed. Then, the role of heat and pressure loss along the gas flow path is investigated to determine whether liquid formation is likely to occur for three unique compressors. For this investigation, conjugate heat transfer models of the suction pulsation bottle are used to identify regions where liquid dropout is predicted. Results of these investigations are presented. Next, liquid carryover from the upstream scrubber is considered. Multiphase models are developed to determine how the multiphase fluid flows through the complex pulsation bottle flow path. Two liquid droplet size distributions are employed in these models. Descriptions of the modeling techniques, assumptions, and boundary conditions are provided.

This paper also presents methods of liquid handling and removal as potential solutions to issues related to wet-gas ingestion. These investigations identify some possible solutions that could be implemented in either new or existing compression systems that are prone to problems with liquid ingestion.