Size a rich oil demethanizer column: diameter, trays, reboiler duty, and methane stripping, per GPSA 19.
Leave off for a stripping-only demethanizer (C₁ to residue/fuel gas, no condenser duty).
| Parameter | Typical Range |
|---|---|
| Column Pressure | 75–200 psig |
| Reboiler Temperature | 250–400°F |
| Theoretical Stages | 6–14 |
| Tray Efficiency | 45–65% |
| C₁ in Bottoms Spec | 0.5–2.0 mol% |
| Dissolved Gas Loading | 3–15 SCF/gal |
Column Diameter (Souders-Brown):
Where CSB depends on tray spacing. Design velocity = Uflood × flood fraction. Column cross-section sized for overhead vapor traffic.
Function: The rich-oil demethanizer strips dissolved methane and ethane from absorber rich oil. Overhead vapors (primarily C₁/C₂) are returned to the absorber or fuel system. Bottoms (demethanized rich oil) proceed to the oil purification still for NGL recovery.
Understand rich-oil demethanizer design, reboiler selection, and stripping optimization
The rich-oil demethanizer strips dissolved methane and ethane from rich absorption oil to produce NGL-laden oil for downstream fractionation. It is a key column in lean oil absorption plants.
Stripping efficiency measures the percentage of dissolved methane removed from the rich oil. The calculator uses the Kremser stripping short-cut (GPSA §19): a stripping factor S = K·V/L is computed for each light component from its K-value at column P/T, and the Kremser function φ = (S−1)/(SN+1−1) gives the fraction remaining in the liquid. The number of theoretical stages N is solved so the methane bottoms spec is met.
The calculator sizes columns based on typical parameters including rich oil flow rate, dissolved gas composition, column pressure, tray spacing, and reboiler temperature. Results include diameter, tray count, and overhead gas rate.
Rich-oil demethanizer columns are designed per ASME Section VIII for pressure containment and the GPSA Engineering Data Book §19 (Fractionation & Absorption) Kremser short-cut for process sizing. The calculator reports column diameter (Souders-Brown), tray count, reboiler duty, and component recoveries; it does not estimate vessel weight.