The Research Of The Compatibility And Fouling Behavior In Blending Heavy Oils

The inferior heavy oils have received more attention in the recent years. In the modernrefineries, in order to improve the economic performance, more and more inferior heavy oilshave been blended to process. But there may be incompatibility between different heavy oils,which may lead to the deposition or fouling in the surface of refining devices, such as pipes,heat exchangers and reactors. The incompatibility may cause the increase of heat resistance ofthe pipelines and may have bad effects on the fluidity of feedstock. In the most severe cases,the device may be clogged up and must be shut down.In order to avoid the accidents caused by the deposition on the refinery device, thestability of the feedstock in the thermal processing must be estimated. Aimed at the reality ofthe refinery, a heavy oil stability evaluating system was designed and manufactured tosimulate the fluidity of the heavy oils in the refining equipment. The thermal stability of theinferior heavy oils and their blending oils could be detected by the average fouling rate of thefeedstock with the heavy oil stability evaluating system. And the operation conditions werefound out by a serious of experiments. On this basis, an evaluation assessment of blendingstability of different heavy oils was proposed to detect the thermal stability. Moreover, thecolloidal stability measured by the mass fraction normalized conductivity and SARA analysiswere conducted under static condition. The differences and relationships detected underthermal condition and static condition were discussed.The investigation showed that there was a correlation between the colloidal stabilityunder static condition and the stability under thermal condition. The colloidal stability wasmainly related to the aggression and flocculation on the microscopic level, while the foulingrate was the reflection of the integrated effects of colloidal stability and operation conditionson the macroscopic level. The two methods could respectively describe the stability of thefeedstock under static and thermal conditions. Moreover, the average fouling rate measuredby the heavy oil stability evaluating system was affected by the colloidal stability and theoperation conditions of the device. The more stable of the heavy oil and the faster it flows, theless the fouling rate it has. And the fouling rate of the heavy oil was affected by the colloidal stability on microscopic level and the operation condition on macroscopic level.