Fractionation Design and Operations Reference
Packing Selection
Module from the Fractionation Design and Operations Reference curriculum.
PACKING SELECTION — RANDOM & STRUCTURED · Packing Type Comparison
| Packing Type | Examples | HETP (ft) | Capacity | Pressure Drop | Best Application | Cost |
|---|---|---|---|---|---|---|
| Random — 1st gen | Raschig rings, Berl saddles | 3-5 | Low | High | Obsolete, replacement only | Low |
| Random — 2nd gen | Pall rings, Intalox saddles | 2-3 | Moderate | Moderate | General service, fouling OK | Low-Medium |
| Random — 3rd gen | IMTP, Nutter rings, Raschig Super-Ring | 1.5-2.5 | High | Low | High capacity, good efficiency | Medium |
| Structured — sheet metal | Mellapak, Flexipac, Koch-Sulzer | 1.0-2.0 | Very high | Very low | Vacuum distillation, revamps | High |
| Structured — gauze | Sulzer BX, Koch Flexeramic | 0.5-1.0 | Moderate | Low | Highest efficiency, lab/pilot scale | Very high |
| Structured — grid | Koch Flexigrid, Sulzer MellaGrid | N/A (mass transfer device) | Very high | Very low | High-capacity liquid collection | Medium |
| Packing vs. Trays Decision Guide | ||||||
| Choose PACKING when: • Vacuum service (low ΔP required): structured packing ΔP = 0.1-0.5 inH2O/ft • Corrosive service: ceramic or plastic packing, no metal internals • Small diameter columns (<3 ft): packing more practical than trays • Revamp for more capacity: replace trays with structured packing • Low liquid rates: packing handles low L/V better than trays Choose TRAYS when: • Fouling service: trays are easier to clean and more fouling-tolerant • High liquid rates: trays handle high liquid loads more reliably • Wide operating range needed: valve trays have good turndown (4:1) • Heat integration: easy to install draw trays for pumparounds • Large diameter columns (>12 ft): tray design is well-established • Solids present: trays can handle small amounts of solids Consider EITHER when: • Moderate conditions, clean service, no specific driver for one or the other • Cost comparison drives the decision (trays often cheaper for large columns) |
Source: Fractionation_Design_Ops_Reference_v1.xlsx · Sheet: Packing Selection
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