Flow Rates & Vessel Type
Determines liquid level and retention time criteria
MMscfd
At standard conditions (14.696 psia, 60°F)
bpd
Total liquids (oil + water for 3-phase)
Operating Conditions
psig
K-factor decreases above 100 psig
°F
Air=1.0
Natural gas: 0.55-0.80 typical
Water=1.0
Crude oil: 0.80-0.95; Condensate: 0.70-0.80
Separation Design
Base K-factors at P < 100 psig per GPSA
min
2-phase: 1-3 min | 3-phase: 3-10 min | Scrubber: 0.5-2 min
-
Optimal: 2.5-4.0 | Acceptable: up to 6.0
Engineering Notes:
- Souders-Brown Equation: Vt = K × √[(ρL - ρG) / ρG] determines maximum allowable gas velocity
- Pressure Correction: K-factor decreases 25-40% as pressure increases from 100 to 1000+ psig
- Sizing Basis: Vessel sized for larger of gas capacity or liquid retention requirements
- Standard Sizes: Diameters rounded to API 12J standard vessel sizes
📚 Learn the Theory
Comprehensive guide to ASME Section VIII pressure vessel design, Souders-Brown equation derivation, and separator sizing methodology.
Souders-Brown Equation
Vt = K × √((ρL - ρG) / ρG)
Vt = Terminal velocity (ft/s)
K = Souders-Brown constant (adjusted for pressure)
ρL = Liquid density (lb/ft³)
ρG = Gas density (lb/ft³)
K-Factor Reference (GPSA)
| Internals | K (base) |
|---|---|
| Wire Mesh Pad | 0.35 |
| High-Eff. Mesh | 0.40 |
| Multi-Cyclone | 0.50 |
| Vane Pack | 0.20 |
| Gravity Only | 0.10 |
Standards & References
-
GPSA
Section 7: Separation Equipment, 14th Edition -
API Specification 12J
Oil and Gas Separators, 8th Edition -
Arnold & Stewart
Surface Production Operations, Vol. 1 -
ASME Section VIII
Pressure Vessel Design Code