Fuel handling: which of the following fuels typically does not require preheating for storage and for proper atomisation through burners under normal operating conditions?

Introduction:
Different liquid fuels demand different handling strategies. Heavy fuels require heating to reduce viscosity for pumping and atomisation; lighter fuels can be pumped and atomised without preheat. Knowing which fuels need preheat prevents burner problems, poor combustion, and operational upsets.

Given Data / Assumptions:

• Choice set spans heavy, viscous streams (tar, bitumen, PCM) and lighter middle distillates (LDO).
• Normal storage and burner atomisation conditions are assumed (no extreme cold).
• Goal: identify the fuel that does not need preheating.

Concept / Approach:
Viscosity governs pumpability and atomisation quality. Heavy residues (tar, bitumen, pitch-like PCM) must be heated to flow and to atomise. Even certain grades of furnace oil require moderate preheat. In contrast, light diesel oil has relatively low viscosity and can be stored and atomised at ambient temperatures in most climates without dedicated preheaters.

Step-by-Step Solution:
1) Rank fuels by viscosity: tar/bitumen/PCM ≫ furnace oil > LDO.2) Apply handling rule: heavier fuels need heat; light distillates typically do not.3) Select LDO as the fuel that does not require preheating.

Verification / Alternative check:
Plant operating manuals specify heater setpoints for heavy fuel oil systems, while diesel burners and storage tanks are commonly unheated except in severe cold conditions.

Why Other Options Are Wrong:
Tar/bitumen/PCM: Very high viscosity; preheat is essential.Low-viscosity furnace oil: Often still needs mild preheat to reach atomisation viscosity.

Common Pitfalls:
Assuming “furnace oil” is always thin enough to avoid preheat; grade and ambient temperature matter.

Final Answer:
Light diesel oil (LDO)