GPSA Ch. 16
| Process Type | C₃ Recovery | Cold Sep. Temp |
|---|---|---|
| Turboexpander | 95–99% | −120 to −140°F |
| JT Valve | 70–85% | −40 to −80°F |
| Mech. Refrigeration | 80–90% | −20 to −40°F |
| Lean Oil Absorption | 60–80% | 80–100°F |
Isentropic Expansion (Turboexpander):
Where T1, P1 = inlet conditions, P2 = column pressure, k = ratio of specific heats, ηexp = isentropic efficiency. Lower temperatures drive higher C₃+ recovery.
Joule-Thomson Expansion:
Where μJT = Joule-Thomson coefficient (°F/psi), ΔP = pressure drop across the valve. No work recovery — lower efficiency than turboexpander.
Recovery Efficiency: Recovery depends on cold separator temperature, which is set by expansion ratio and inlet conditions. Ethane rejection is achieved by operating the demethanizer to keep C₂ in the overhead with methane.
Column Sizing: Demethanizer column diameter sized from vapor/liquid traffic using Fair’s flooding correlation at the design flood fraction.
Understand propane recovery process design, turboexpander vs. JT valve trade-offs, and NGL plant optimization
The calculator supports turboexpander, JT valve, mechanical refrigeration, and lean oil absorption processes for Cā+ recovery. Each process type has different recovery efficiency and economics per GPSA Ch. 16.
Ethane rejection means operating the demethanizer to reject ethane into the residue gas while recovering propane and heavier components. This is common when ethane has low market value or pipeline specs require low heating value.
The demethanizer column diameter is sized from vapor/liquid traffic using Fair's flooding correlation at the design flood fraction. The calculator determines tray count, column diameter, and reboiler/condenser duties per GPSA Ch. 16.
Propane recovery efficiency varies by process type: mechanical refrigeration achieves 70ā90%, JT expansion 60ā80%, and turboexpander processes 90ā99%+ depending on feed richness and operating conditions.