Question

Engineers in Brazil do not have to worry as much about the CLOUD POINT or the POUR POINT of their biodiesel as Canadian engineers do. Define these terms and suggest two ways problems relating to them can be addressed.

Answer 1

cloud point refers to the temperature below which wax in diesel or biowax in biodiesels form a cloudy appearance.

The presence of solidified waxes thickens the oil and clogs fuel filters and injectors in engines.

The wax also accumulates on cold surfaces (e.g. pipeline or heat exchanger fouling) and forms an emulsion with water.

Therefore, cloud point indicates the tendency of the oil to plug filters or small orifices at cold operating temperatures.

the pour point—the temperature below which crude oil becomes plastic and will not flow—is important to recovery and transport and is always determined.

SOlutions/remedies :

• Cold filter or cold settle feedstock oil. This is simply leaving the oil outside where it can freeze and melt. Then siphon off the liquid stuff on top to use for biodiesel.
• Cold filtering finished biodiesel after blending with diesel. This promotes the precipitation of waxes while keeping biodiesel liquid. Then filter or siphon off the liquid on top.
• Cold filtering finished biodiesel before blending. Chilled to -3C then filtered through cold wood chips.