Thermal cracking of crude oil and crude oil fractions containing pitch in an ethylene furnace

A process for pyrolyzing a crude oil or crude oil fraction containing pitch feedstock comprising feeding said feedstock to a first stage preheater within a convection zone of an olefins pyrolysis furnace, heating said feedstock to a temperature at which non-coking fractions and a portion of coking fractions are fully evaporated to a gas, while the remaining portion of coking fractions are maintained in a liquid phase, wherein the gas/liquid weight ratio of said feedstock in the first stage preheater is within a range of 60/40-98/2, withdrawing the gas/liquid mixture from the first stage preheater and feeding the gas/liquid mixture to a vapor-liquid separator, separating the gas from said gas/liquid mixture in the vapor-liquid separator and removing said gas from the vapor-liquid separator, feeding said removed gas to a second stage preheater in the convection zone, heating said gas in the second stage preheater, and feeding the second stage preheated gas to a radiant zone in the pyrolysis furnace.

A process for pyrolyzing a crude oil or crude oil fraction containing pitch feedstock comprising feeding the feedstock to a first stage preheater in a convection zone of an olefins pyrolysis furnace further comprising a radiant zone, heating the feedstock in the first stage preheater to a temperature of at least 400° C., and feeding a dilution gas to said feedstock in the first stage preheater while heating said feedstock within the first stage preheater, wherein the gas-liquid weight ratio at an exit of said first stage preheater ranges from 60/40-98/2.