The Wax Problem in Middle Distillates
Normal paraffins (n-alkanes) can comprise up to 30% of a typical diesel fuel. These are the least soluble components in the fuel, as temperature falls below the cloud point, they crystallize into plate-like structures that form an interlocking network. Without treatment, this network blocks fuel filters, restricts fuel lines, and prevents engine start or sustained operation in cold conditions.
Three key parameters define diesel cold weather operability: Cloud Point (CP), where wax first becomes visible; Pour Point (PP), the lowest temperature at which fuel flows; and Cold Filter Plugging Point (CFPP), the critical filterability measure for vehicle operability. Cold Flow Improvers (CFIs) address CFPP and pour point, which are where operational risk concentrates.
How Cold Flow Improvers Work
The dominant CFI chemistry is based on ethylene copolymers, particularly ethylene-vinyl acetate (EVA) copolymers. These polymers co-crystallize with growing wax at the cloud point, disrupting normal plate crystal growth and producing smaller, more rounded crystals with less tendency to interlock and block filter pores. The result is typically a 5–15°C reduction in CFPP and a 10–25°C improvement in pour point at treat rates of 200–2,000 mg/kg.
CFI performance is highly fuel-specific. The additive must be matched to the paraffin chain length distribution of the base fuel. A CFI optimized for straight-run diesel from a paraffinic crude may perform differently on a hydrocracked or FCC-blended fuel. Lamurindo’s technical team matches additive to fuel for optimal performance.
Application by Fuel Type
| Fuel / Application | Cold Climate Risk | CFI Benefit |
|---|---|---|
| Road Diesel (ULSD) | Filter plugging in cold regions; vehicle operability failure below cloud point | CFPP improvement to meet seasonal specifications (EN 590 Grade D–F, etc.) |
| Marine Gas Oil (MGO) | Cold port conditions; onboard tank wax formation at low sea temperatures | Maintain IGF-compliant operability; prevent purifier and separator plugging |
| Heating / Distillate Oil | Wax setting in outdoor storage tanks; pump and burner failure in winter | Pour point reduction for reliable pumping and burner operation |
| Biodiesel Blends | FAME raises CP and CFPP of blends vs. neat diesel | Partially offsets FAME cold flow penalty; complementary to FAME-specific CFIs |