Process Function

Rich glycol leaving the contactor contains dissolved light hydrocarbons absorbed from the gas stream at high pressure. As glycol pressure reduces entering the regenerator, these hydrocarbons flash to vapor creating operational problems. The flash tank provides controlled pressure reduction allowing hydrocarbon vapors to separate before glycol enters the still column. Gas exits overhead for fuel recovery or compression while degassed glycol flows to regeneration at reduced hydrocarbon content.

Design Configuration

Vertical or horizontal pressure vessels sized for glycol flow rate and vapor separation requirements. Operating pressure typically 50-100 psig provides adequate pressure drop from contactor while maintaining liquid glycol. Internal baffles or mist eliminators prevent glycol carryover in overhead vapor. Inlet devices reduce velocity enabling gas-liquid disengagement. Level control maintains glycol inventory preventing overflow or gas breakthrough to regenerator.

Operational Benefits

Removes 60-80% of dissolved hydrocarbons reducing reboiler fuel requirements by preventing unnecessary vaporization of light ends. Cleaner glycol regeneration improves still column efficiency. Recovered flash gas provides fuel value or returns to process. Reduced hydrocarbon loading minimizes environmental emissions from regenerator overhead. Lower regenerator pressure requirements simplify equipment specifications.

System Integration

Flash tanks install between contactor and glycol circulation pump or after the pump before regenerator inlet. Pressure control valves manage flash tank pressure optimizing vapor separation. Overhead vapor routes to fuel gas system, compressor suction, or flare. Level instruments integrate with regenerator feed control. Temperature monitoring ensures adequate flashing without glycol cooling.

Applications

All glycol dehydration systems processing rich gas with significant hydrocarbon content. Particularly important for high-pressure contactors above 800 psig where hydrocarbon solubility increases substantially. Essential for maintaining regenerator efficiency and reducing operating costs in gas processing plants, production facilities, and pipeline conditioning stations.

Construction Standards

ASME Section VIII pressure vessel design with full code compliance. Carbon steel construction with internal coatings if required. Properly sized relief valves protect against overpressure. Drain connections enable maintenance and cleaning. Insulation optional depending on ambient conditions and process requirements.

ERGIL glycol flash tanks improve dehydration system efficiency through effective hydrocarbon removal, reducing energy consumption and enhancing overall performance.