What is the purpose of the Coker in a refinery?

The Coker serves a crucial role in a refinery by taking heavy oils and converting them into lighter, more valuable products. This process involves thermal cracking, where heavy residual oils, typically referred to as "heavy bottoms," are subjected to high temperatures and pressures in the Coker unit. The thermal cracking breaks down these heavier fractions into lighter hydrocarbons such as gasoline and diesel. This conversion not only maximizes the yield of useful products from the less desirable heavy feedstock but also helps improve the overall efficiency and profitability of the refining process.

The other options address different processes or units found in a refinery but do not describe the primary function of the Coker effectively. For instance, the conversion of waste water, sulfur stripping, and oxidation of hydrocarbons pertain to other units and processes within the refinery, focusing on different aspects of refining operations.