Petroleum Processing – Name the Operation: High-Temperature, High-Pressure Heating of Crude What is the process called in petroleum refining where crude oil (or heavy fractions) is heated to high temperature under high pressure to break large hydrocarbon molecules and thereby increase the yield of lighter distillates such as gasoline and kerosene?

Introduction / Context:
Modern refineries tailor product slates by converting heavy hydrocarbons into lighter, higher-value products. The key conversion route uses heat (and sometimes catalysts) to break carbon–carbon bonds in long-chain molecules, increasing gasoline and middle distillate yields. Identifying this operation is basic refinery knowledge.

Given Data / Assumptions:

• Feed: crude oil or heavy fractions (e.g., gas oils, residues).
• Operating conditions: elevated temperature; often elevated pressure (especially in thermal cracking).
• Goal: increase yield of lighter fractions.

Concept / Approach:

Cracking is the general term for processes that cleave large hydrocarbons into smaller molecules. Thermal cracking uses heat (and pressure) alone; catalytic cracking adds zeolitic catalysts at moderate pressures and high temperatures to improve selectivity and lower severity. By contrast, fractional distillation merely separates components by boiling point without chemical change, and carbonisation pertains to coal pyrolysis rather than petroleum refining.

Step-by-Step Solution:

Verification / Alternative check:

Process-flow diagrams for refineries show cracking units (fluid catalytic cracking, hydrocracking, visbreaking) as primary conversion steps producing gasoline-range and middle distillates, consistent with the description.

Why Other Options Are Wrong:

Carbonisation applies to coal, not crude oil. Fractional or 'full' distillation separates but does not convert. Reforming changes structure (e.g., naphtha to aromatics) but does not primarily target chain scission to boost overall light-yield from heavy feeds.

Common Pitfalls:

Confusing cracking with reforming or isomerization; assuming pressure alone defines the operation—temperature and catalytic environment are just as crucial.

Final Answer:

cracking