Condensation Formation

First-stage compression heats gas 50-100°C. Intercoolers drop temperature to near-ambient for efficient second-stage compression. Cooling condenses water vapor and heavy hydrocarbons. Without removal, these liquids enter downstream stages causing valve damage in reciprocating compressors or erosion in centrifugals.

Separator Configuration

Vertical or horizontal vessel between compressor stages after intercooler. Gas inlet from cooler, mist eliminator removing droplets, gas outlet to next stage suction, liquid sump with level control and drain. Simple design focuses on reliable liquid removal rather than complex internals.

Operating Pressure

Pressure matches interstage conditions typically 100-600 psig for two-stage systems, higher for multi-stage compression. Design accommodates pressure between stages with appropriate safety margin. Lower pressure than suction scrubber allows lighter construction.

Liquid Volume

Condensate quantity depends on gas composition, compression ratio, and cooling effectiveness. Rich gas produces more liquids. Higher pressure increases condensation. Proper vessel sizing handles maximum liquid rates with adequate surge capacity preventing level upsets.

Material Selection

Carbon steel suits most hydrocarbon service. Stainless steel for sour gas or corrosive conditions. Mist eliminator materials handle interstage temperature and moisture. Design accommodates thermal cycling during startup and load changes.

Applications

Multi-stage gas compression in gathering systems, pipeline booster stations, gas plant compression trains, refrigeration systems, and vapor recovery units. Any multi-stage compression benefits from interstage liquid removal protecting equipment and maintaining efficiency.

Level Control

Level switches activate drain valves removing condensate to closed systems. High-level alarm warns before liquid reaches gas outlet. Some installations use level transmitters with continuous control. Simple reliable systems suit unmanned compressor stations.

Performance Impact

Removes condensate preventing liquid carryover to downstream stages. Protects compressor internals from damage. Maintains compression efficiency by eliminating liquid in gas stream. Recovers valuable condensate rather than passing through compressor as liquid.

Energy Benefits

Dry gas between stages compresses more efficiently than wet gas. Removing liquids reduces power consumption 2-5% in typical applications. Condensate recovery adds product value. Combined benefits provide fast payback on separator investment.

Construction Standards

Design per ASME Section VIII Division 1 with materials for interstage pressure and temperature. Drain system sized for maximum liquid rates. Relief protection prevents overpressure. Complete documentation with separator calculations and material specifications.

ERGIL interstage separators protect multi-stage compressors while improving efficiency through liquid removal between compression stages.