Reaction Kinetics Analysis Of Heavy Oil Visbreaking

With the consumption of light crude oil,the extraction and processing of heavy oil play an increasingly important role in international energy security.In this paper,by applying supercritical benzene(scbenzene)to heavy oil visbreaking to alleviate the influence of diffusion limitation on the reaction kinetics,the thermal cracking of heavy oil is transferred from a high-viscosity oil phase with a viscosity of 10-3 Pa.s to a viscosity of 10-5 Pa.s in the scbenzene environment.The research first analyzed the effects of benzene-oil ratio,benzene density and reaction temperature on the visbreaking of Changling slag,and applied various analytical methods to analyze the cracked products.The experimental results show that by adjusting the operating conditions,the viscosity reduction effect can be improved and the condensation of heavy oil can be effectively inhibited.The study then examined the visbreaking behavior of heavy oil with high metal and high asphaltene content in the scbenzene environment.Tahe regular residue and Canadian oil sands bitumen fraction(OS350)with boiling point from 350? to final boiling point(OS350)can effectively reduce viscosity through visbreaking.The asphaltene content in the oil sand asphalt fraction(OS500)with a boiling point from 500? to the final boiling point is 19.3 wt%,and the total content of Ni and V in the asphaltene is 1300 ppm.The presence of high metal content promotes the large-scale supramolecular aggregation of asphaltenes through electrostatic interactions,thereby accelerating the condensation of asphaltenes to coke.Due to the high content of asphaltenes and the presence of high metal content in the asphaltenes,OS500 exhibits an unexpectedly strong tendency to condense,making it difficult to modify by visbreaking.The study further established a five-lumped reaction kinetic model for visbreaking based on the boiling point distribution of cracked products.Model analysis shows that,although it is generally believed that the predominance of the visbreaking process is the lumped reaction based on dealkylation,there is always competition between dealkylation and condensation throughout the visbreaking process.Since the influence of diffusion restriction on reaction kinetics is alleviated,the viscosity reduction efficiency is effectively improved.At the same time,the condensation-based lumped reaction with an activation energy of up to 306 kJ/mol is more sensitive to changes in reaction temperature,which significantly shortens the time window for visbreaking at high temperatures.