Behavior Of Oil Oxidation And Evolution Of Products Under Different Temperatures During Combustion Process

The substances of thermal reaction of oil during heavy oil combustion is a process of the complicate combination of a series of chemical reactions,including oxidation reaction,pyrolysis reaction,etc.Previous research is mainly concentrated on the macroscopic properties such as viscosity,acid value,etc.However,the study of the molecular evolution is inadequate.In this paper,0-dimensional combustion cell,three-dimensional combustion model and rheometer are used to simulate combustion process,and oil from Xinjiang Karamay is used as original sample.In this process,a variety of chemical instrument analysis means is adapted,such as GC-FID,GC-MS,and FT-ICR MS,to detailed analysis the differences of the composition of oil before and after combustion process.Multiple field practice shows that the acid number of crude oil increases obviously after combustion process.The quality of oil with high acid number is poor,and transporting such oil could cause corrosion to mining equipment and transportation lines,and even lead to site accidents.The oil is difficult to refine as well.This paper starts with the explanation of the rising of acid number.Analyzing the composition of products and establishing the reaction process of crude oil in the process of combustion.During the experiment,it is found that basic nitride and polycyclic aromatic compounds in crude oil are relatively stable,and present only slight changes in the process of combustion.Thus,they do not affect the quality of crude oil or the reaction process.However,the acidic compounds in oil vary significantly in the reaction process and present a three-stage reaction.A variety of oxygen-containing acidic compounds,mainly O2 compounds,can be detected by chemical equipment.These compounds lead to the change of acid number of crude oil after combustion.In order to verify the three-stage reaction,oil from different positions in 3-dimensional combustion cell and oil treated under different temperatures are analyzed and compared.The results confirm the accuracy of the progress of the evolution of acidic number,and the possible effect of flow field on the product is excluded.After that,the reaction mechanism of asphaltene and non-hydrocarbon is analyzed.The results show that the change of asphaltene is slightly different from that of low molecular weight compounds,but on the whole,it fits the three-stage reaction.