Protection of reciprocating compressor packages typically involve off skid-station liquid separation technology as well as a separator(s) mounted on skid. Generally, the on-skid separator is incorporated into the acoustic manifold design in the vertical bottle which often acts as a volume in the “volume-choke-volume” primary acoustic filter. This on skid bottle-separator typically locates the inlet gas nozzle near or below mid height of the bottle. A reduction in velocity of the gas as it enters the bottle, allowing gravity separation as the gas move vertically, and a final stage of mist elimination in the form of mesh pads or vane packs before leaving the separator at a higher elevation. Carry over liquids entering the compressor are an ongoing problem, leading to increasing levels of compressor issues from poor valve performance and decreased valve life, to failed internals including pistons and rods. Liquid transients in compressors leading to part failures can be difficult to diagnose, often leading to finger pointing between manufactures, end users and packagers. Recent work done by the GMRC on wet gas carry over into compressors has indicated that condensation due to heat transfer between the on-skid scrubber exit and compressor valve inlet is not likely a large source of liquid formation. Droplet carry over leaving the skid scrubber is more likely the source of liquid ingestion, either through accumulation into various regions of the manifold followed by slugging of this liquid into the cylinder, or droplet carry over directly into the cylinder. Despite the long term need for improved liquid protection, there has been little significant change and improvement in technology. This is in part due to the cost competitive nature of the industry, and the challenge to put suitable technology on the skid. On skid scrubbers, must be able to effectively participate in the acoustic design, must offer low pressure drop so as to not degrade compressor performance, maintain separation performance in transient flows, have sufficient flow turn down, and realistically require no internal maintenance. Standalone gathering applications will need to be able to handle larger liquid slugging. This paper looks at the development of separation technology suitable for on skid application. Considerations are given for fitting in current typical foot print, the impact on the acoustic/mechanical design, and reductions in instrumentation requirements.
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