1 of 10

PETROLEUM REFINERY OPERATIONS IN PROCESS INDUSTRIES�(2025-2026)

​

A.S.PERIASAMY MANIKANDAN

Associate Professor

Department of Chemical Engineering

Kongu Engineering College, Perundurai

​

​

2 of 10

CLASSIFICATION

  • Crude oil is classified primarily by its density (API gravity) and sulfur content (sweet vs. sour), which determine its market value and ease of refining
  • . Major categories include Light/Sweet (highly valuable, easy to process) and Heavy/Sour (dense, requires more processing).

3 of 10

  • Main Classification Methods:
  • By API Gravity (Density): Measures how light or heavy the oil is compared to water.
    • Light: API > 31.1° (e.g., WTI).
    • Medium: API 22.3°–31.1°.
  • Heavy: API 10°–22.3°.
  • Extra Heavy (Bitumen): API < 10°.

​

4 of 10

  • By Sulfur Content:Sweet: < 0.5% sulfur (preferred, lower processing required).
  • Sour: ≥is greater than or equal to
  • ≥
  • 1.0% sulfur (requires more refining).

​

5 of 10

  • By Chemical Composition:Paraffinic: High in paraffin wax, high viscosity index.
  • Naphthenic: Contains cyclic hydrocarbons.
  • Aromatic: Contains benzene ring structures.
  • Asphaltic: High in asphalt content

​

6 of 10

CRUDE OIL CHARACTERISTICS

  • Key Characteristics
  • Density & API Gravity: Light oil has high API (>31.1°), while heavy oil has low API (<22.3°). Lighter oils are generally more valuable as they yield more gasoline and diesel.
  • Sulfur Content: Classified as "sweet" (<0.5% sulfur) or "sour" (>0.5% sulfur). Sweet crude requires less processing.
  • Viscosity: Ranges from thin, light crudes to heavy, viscous, or even semi-solid/tar-like substances.

​

7 of 10

  • Chemical Composition: Composed of alkanes (paraffins), naphthenes, and aromatics.
  • Physical State: Found as liquid or gaseous in underground reservoirs.
  • Acid Content (TAN): Total Acid Number measures organic acid content, affecting corrosion rates during refining

​

8 of 10

  • in oil and gas, C1, C2, C3, and C4 refer to light hydrocarbon compounds named by their carbon atom count: C1 is methane, C2 is ethane, C3 is propane, and C4 is butane, with C1-C4 typically being gases at standard conditions, forming natural gas and LPG, and crucial for petrochemicals and fuel. 

​

9 of 10

KEY USES OF REFINED CRUDE OIL:

  • Key Uses of Refined Crude Oil:
  • Transportation Fuels: Gasoline for cars, diesel for trucks, and jet fuel for airplanes.
  • Petrochemicals & Plastics: Raw materials (naphtha) for making plastics, synthetic rubber, fibers, and pharmaceuticals.

​

10 of 10

  • Heating & Electricity: Heating oil for buildings and fuel for power generation.
  • Industrial/Construction: Asphalt/bitumen for roads, lubricants for machinery, and waxes.
  • Agriculture: Feedstock for producing fertilizers and pesticides

​