Straight-run distillation yield: estimate a typical kerosene cut percentage (by volume) obtained directly from crude oil without cracking or reforming, under conventional atmospheric distillation conditions.

Introduction / Context:
In a fuels refinery, the crude distillation unit (CDU) separates crude into straight-run fractions: gases, naphtha, kerosene, diesel/gasoil, and residue. Typical yields depend on crude assay (paraffinic vs naphthenic), cut-point definitions, and plant objectives. This question asks for a representative kerosene yield from straight-run distillation only (no conversion units included).

Given Data / Assumptions:

• Average mixed crudes with standard atmospheric cut points.
• Yield expressed on a typical volume percent basis.
• No hydrocracking or reforming contributions; strictly straight-run kerosene.

Concept / Approach:
Crude assays commonly show kerosene fractions in the approximate range of single digits to low teens by volume for many world crudes. While light, kerosene is narrower and smaller than total naphtha plus diesel cuts. A commonly cited reference value for general questions is about 10 percent straight-run kerosene, acknowledging that real values vary by crude type and unit targets.

Step-by-Step Solution:

Verification / Alternative check:
Crude assay examples and refinery planning texts often place straight-run kerosene near 8–12 percent for benchmark medium crudes, supporting a 10 percent nominal figure.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing total kerosene pool (including hydrocracker or coker distillates) with straight-run kerosene; the question is strictly about atmospheric distillation output.

Final Answer:
10