GPSA 14th Ed. · GPA 2145 · Ethane, Propane & C4+ Recovery Economics
Understand NGL recovery processes, cryogenic plant design, and optimization strategies
It calculates NGL recovery economics using GPSA-based material balance, including ethane/propane recovery optimization, frac spread analysis, and residue gas specifications.
Frac spread analysis evaluates the economic difference between selling natural gas as a whole stream versus recovering and selling individual NGL components separately.
The calculator optimizes ethane and propane recovery rates while evaluating residue gas specifications and overall NGL recovery economics.
Frac spread is the difference between NGL product value and the shrinkage cost of the gas used to produce those liquids. It is the key economics driver for NGL recovery decisions, determining whether ethane rejection or recovery is more profitable.
Ethane rejection is common when ethane price falls below approximately 35% of propane value. Plants designed with 2-3 operating modes (full recovery, ethane rejection, bypass) add optionality value to adapt to changing market conditions.
Typical US pipeline specifications include heating value of 950-1,100 BTU/SCF gross, Wobbe Index of 1,310-1,390, hydrocarbon dewpoint below 15°F at 800 psig, CO2 below 2 mol%, and H2S below 4 ppmv.
Rich gas with more than 3 GPM (gallons per Mscf) typically justifies turboexpander cryogenic processing. Lean gas below 1.5 GPM may favor JT valve, refrigeration only, or plant bypass. Operating costs for cryogenic plants are typically $0.08-0.20/gal NGL.