Visbreaker Furnace

Visbreaking Process VISBREAKING PROCESS
Visbreaking, a mild form of thermal cracking, significantly lowers the viscosity of heavy crude-oil residue without affecting the boiling point range. Residual from the atmospheric distillation tower is heated (800-950 degrees F) at atmospheric pressure and mildly cracked in a heater. It is then quenched with cool gas oil to control overcracking, and flashed in a distillation tower. Visbreaking is used to reduce the pour point of waxy residues and reduce the viscosity of residues used for blending with lighter fuel oils. Middle distillates may also be produced, depending on product demand. The thermally cracked residue tar, which accumulates in the bottom of the fractionation tower, is vacuum flashed in a stripper and the distillate recycled.
VISBREAKING PROCESS.
Feedstock   From   Process   Typical products . . . . . To
Residual Atmospheric tower & Vacuum tower Decompose Gasoline or distillate . . Hydrotreating
Vapor . . . . . . . . . . . .  Hydrotreater
Residue . . . . . . . . . . . Stripper or recycle
Gases . . . . . . . . . . . . Gas plant