Characteristics and Fouling Tendencies of Selected Malaysian Crude Oils

Fouling on the surfaces of heat exchangers, particularly in crude pre-heat train is one of the major challenges faced in crude oil refining. The accumulation of unwanted deposits on the surfaces of heat exchangers is referred to as foulant which causes obstacle to the heat transfer mechanism resulting in lost efficiency. Virgin foulant deposits collected from a local refinery were characterized for its physical and chemical properties using various sophisticated equipment to understand the properties and deposition mechanisms. From this studied it was found that wax formation was the major foulant material. The wax deposition follows two different mechanism routes and reactions i.e. in tube side a slow and steady deposition aided by polymerization reaction, while in the shell side a rapid sedimentation due to film boiling is observed. Based on the fouling tendency its compositions and properties, selected properties of a crude oil associated to it were identified. Three Malaysian crude oils tagged as A, B and C was selected. Each of chosen crude were characterized individually and later blended in accordance to common practice in a local refinery. Asphaltene compatibility parameter was done for fouling tendencies. From the study it was found that all 3 crudes at the predefined blending ratio are compatibility. Further test to understand asphaltene precipitation behavior was also conducted using Design of Experiment (DOE), Taguchi Orthogonal Array L-16 under the influence of temperature, solvent type and resident time. It was found that temperature has the highest impact and that asphaltene deposition; it decreases with increase in temperature. Asphaltene precipitation was also concluded to be significantly influenced by the presence of low molecular hydrocarbon.