Flash Separation

Liquid propane from upstream equipment contains dissolved lighter components. Pressure reduction vaporizes these dissolved gases. Flash drum provides residence time for gravity separation. Vapor exits overhead. Liquid propane flows to downstream processing or storage.

Operating Pressure

Typical flash pressure 3-10 bar balances light ends removal against propane losses to vapor. Higher pressure leaves more lights in liquid. Lower pressure removes more contaminants but vaporizes valuable propane. Optimization depends on upstream conditions and product specifications.

Drum Design

Horizontal vessel with liquid inlet, vapor space sized for flash gas volume, mist eliminator preventing liquid carryover, vapor outlet to recovery or compression, liquid outlet to storage or processing, level control maintaining inventory.

Vapor Recovery

Flash vapor contains ethane, methane, and some propane. Routes to compression for recovery, fuel gas system, or refrigeration suction depending on facility configuration. Economic decision balances compression costs versus vapor value.

Material Selection

Carbon steel construction per ASME Section VIII suitable for propane service. Design pressure accommodates operating conditions with safety margin. Temperature typically 10-40C depending on ambient and upstream process.

Liquid Quality

Single-stage flash reduces light ends improving propane purity. May achieve specification or require additional separation. Final composition depends on inlet conditions and flash pressure. Critical for meeting vapor pressure requirements.

Applications

Gas plant propane recovery, refinery LPG processing, NGL fractionation, propane storage preparation, and any application requiring simple single-stage propane vapor-liquid separation.

Flash Efficiency

Adequate residence time ensures vapor-liquid equilibrium typically 3-5 minutes. Proper vapor velocity prevents re-entrainment. Temperature stable at flash pressure conditions. Design accounts for varying inlet composition.

Level Control

Maintains liquid inventory for steady downstream flow. High-level protection prevents vapor carryover. Low-level alarm indicates upstream feed issues. Simple automated control coordinates with propane handling system.

Storage Interface

Stabilized propane flows to pressurized storage typically 5-8 bar. Reduced light ends content prevents excessive vapor pressure. Meets storage and transport specifications. Essential preparation for safe propane handling.

Construction Standards

Design per ASME Section VIII for operating pressure. Materials for propane liquid and vapor service. Relief protection against fire exposure per LPG codes. Complete documentation with flash equilibrium calculations.

ERGIL propane flash drums provide efficient single-stage vapor-liquid separation preparing propane for storage or processing in LPG operations.