Furnace oil handling — recommended preheating\nFor a medium-viscosity furnace oil to achieve better burner atomisation, the recommended preheating temperature is approximately ______ °C.

Introduction / Context:
Efficient atomisation of fuel oils in industrial burners depends strongly on viscosity at the burner tip. Preheating reduces viscosity, enabling fine droplets and stable combustion with lower excess air.

Given Data / Assumptions:

• Fuel is a “medium-viscosity” furnace oil (e.g., FO/LSHS grades).
• Standard pressure atomising burner hardware is used.

Concept / Approach:
Typical viscosity–temperature charts for furnace oils show that around 80–100 °C is often required to bring viscosity into the recommended atomisation window (commonly 10–20 cSt at nozzle). Lower values like 50–70 °C often remain too viscous; very high temperatures risk coking and safety issues. Hence, around 90 °C is a widely cited practical target for many medium grades.

Step-by-Step Solution:

Verification / Alternative check:
Burner OEM manuals specify preheat setpoints typically in the 80–100 °C band for medium furnace oils, validating 90 °C as a representative value.

Why Other Options Are Wrong:

• 50–70 °C: often insufficient viscosity reduction.
• 140 °C: unnecessarily high and may promote thermal degradation.

Common Pitfalls:
Ignoring seasonal ambient impacts; keep the preheater control loop tuned to maintain viscosity, not just temperature.

Final Answer:
90