What is "visbreaker"

n. A processing unit in oil refinery that reduces the quantity of residual oil produced in the distillation of crude oil to increase the yield of more valuable middle distillates (heating oil and diesel) by thermally cracking large hydrocarbon molecules in the oil.

A visbreaker is a processing unit in an oil refinery whose purpose is to reduce the quantity of residual oil produced in the distillation of crude oil and to increase the yield of more valuable middle distillates ( heating oil and diesel) by the refinery. A visbreaker thermally cracks large hydrocarbon molecules in the oil by heating in a furnace to reduce its viscosity and to produce small quantities of light hydrocarbons ( LPG and gasoline). The process name of "visbreaker" refers to the fact that the process reduces (i.e., breaks) the viscosity of the residual oil. The process is non- catalytic.