Upgrading the Bottom of the Barrel

Crude oils usually contain substantial yields of heavy hydrocarbons boiling above 600–800 °F. These are referred to as atmospheric and vacuum residual oils, residua, or resids. Resids were primarily used for many years as heavy fuel oils (bunker oil) or various tar or asphalt products. Modern refinery economics and environmental regulations make the processing of residua to light oils and feedstocks for other units desirable and, indeed, necessary in many areas. Several process approaches are available for resid conversion. In this chapter, we explore several of the resid conversion processes, including thermal cracking, visbreaking, delayed coking, Flexicoking™, deep oil FCC, and residuum hydrocracking. A detailed design example of thermal cracker key equipment is provided.