REACTION PROPERTIES OF RESIDUE FRACTIONS FROM LOW SEVERITY UPGRADING

摘要

As heavy oil production increases faster than the supply of diluents, such as natural gas condensate, the need for new strategies to reduce viscosity for pipelining are required. Low-severity upgrading processes for minimal field processing are becoming more attractive, but thermal cracking processes tend to be unstable with time, so that pipelines and storage tanks are fouled with sludge deposits. One mechanism for instability of a processed oil with time is polymerization reactions, which are very sensitive to oxygen and other contaminants. Because this type of instability is driven by chemical reaction, in addition to phase behavior and solubility, we term this phenomenon "chemical instability". The presence of any oxygen in thermally cracked oils may sensitize the mixture by forming peroxides, so that dimers and trimers can form with time. This increase in molecular weight, after processing is complete, is likely a major cause of chemical instability that can lead to sediments or to changes in physical and reactive properties. This presentation will give a case study on how the reactivity of thermally cracked material changes upon contact with air. By using a micro-scale flash coker, we can observe the behavior of thermally processed samples at temperatures of 450-550°C, and gain insights into process performance in downstream cracking and coking units.