Optimization design and performance study of a concentric two-stage cyclonic de-liquidizer

Abstract

To mitigate environmental pollution from venting high-salinity gas wells in Northern Shaanxi, a concentric two-stage cyclonic de-liquidizer was proposed and optimized. Structural parameters were screened via Plackett–Burman design and optimized using steepest ascent and Box–Behnken response surface methodology combined with numerical simulations. The optimal parameters were: two-stage diameter ratio μ= 0.26, secondary swirl chamber aspect ratio n₂= 1.48, primary inlet tangential inclination γ₁= 35°, and overflow pipe insertion depth h = 1425 mm. The optimized separator achieved a peak separation efficiency of 99.88% under inlet flow rates of 5 × 10⁴∼30 × 10⁴ m³/d and liquid volume fractions of 0.01∼1%. Efficiency increased significantly with flow rate up to a critical limit of 25 × 10⁴ m³/d and remained stable under inlet pressures of 1∼6 MPa. An optimal operating window of 20 × 10⁴∼25 × 10⁴ m3/d with liquid fraction below 0.2% is recommended, requiring 4∼6 MPa driving pressure, consistently yielding > 98% efficiency. This study provides a theoretical basis and design guidance for high-salinity gas well venting pretreatment.