Natural Gas Engineering

A: Liquid carryover can still occur because PSV actuation doesn't restore level control or protect internals, upstream liquid backup happens because the failed valve blocks normal outflow without isolating inflow, upstream slugging is credible because flooded inlet devices lose separation efficiency, and overpressure is what the PSV is specifically sized to prevent by relieving vapor space pressure.

A: Alarms aren't credited because API 520 doesn't assign risk reduction factors to them, operator response isn't assumed instantaneous due to human variability, blocked outlet applies to any operating mode not just start-up, and administrative or human actions aren't accepted as safeguards when defining worst-case relief loads.

A: Ten kg/s is low because laminar and liquid assumptions underpredict gas blowdown, fifty kg/s still ignores choked flow behavior at high pressure ratios, five thousand kg/s reflects a different diameter and service class, and a few hundred kg/s aligns with sonic flow through a large-bore opening at 60 bar.

A: Vane packs struggle with sub-10 micron droplets at low density ratios, gravity settling alone won't capture fine mist in gas service, cyclonic inlets act upstream and don't replace final polishing, and a mesh pad selected on K-value addresses droplet capture with known efficiency limits.