Numerical Simulation And Analysis For Contamination Of Batch Transportion Pipeline

Oil products batch transportation can not only decrease construction costs and transportation costs, increase transportation efficiency, but also relieve the damage to environment. However, because different types of oil are transported at the same time, mixed oil will occur at the interface between two different oil. Mixed oil is influenced by many factors such as physical properties of oil, operating conditions. This makes mixed oil control and cutting difficult. So it is of great importance for batch transportation process design and mixed oil disposal to study the mixed oil created in batch transportation and find the rule of concentration distribution in mixed oil plug.Based on computational fluid dynamics and contaminated theory, this paper simulated and analyzed diesel and gasoline batch transportation, using FLUENT and VOF model. For horizontal pipeline, numerical simulation is conducted with gravity and without gravity. Data and figures obtained from the simulation are processed with Tecplot, Excel. Concentration distribution of mixed oil is presented in this paper, and rule and mechanism of forming mixed oil plug is analyzed. Results show that, gravity greatly affects the state of mixed oil, and it’s essential to consider gravity. For horizontal pipeline under the influence of gravity, we simulated the mixed oil for different transportation order, and analyzed the influence of density difference on mixed oil.Mixed oil created in horizontal pipe, concentric reducer pipe and eccentric reducer pipe are numerically simulated. The reasons for forming mixed oil in the three pipes with different transportation order are analyzed. Results show that, when the pipe diameter decrease, under two transportation orders, concentric reducer pipe is more stable than eccentric reducer pipe,and mixed oil plug is shorter, which is easier to control and reprocess mixed oil.when the pipe diameter increase, under two transportation orders, eccentric reducer pipe is more stable than concentric reducer pipe, and mixed oil plug is shorter, which is easier to control and reprocess mixed oil.For 90° vertical elbow with 3 times and 1.5 times curvature radius, mixed oil are numerically simulated. Results show that, under the two transportation order, mixed oil created in 90° vertical elbow with 3 times curvature radius is more stable than that in 90°vertical elbow with 1.5 times curvature radius, and mixed oil plug is shorter, which is easier to control and reprocess mixed oil.This paper considered the influence of gravity, which is more close to actual situation,and the research is closely integrated with engineering. Concentric reducer pipe or eccentric reducer pipe when pipeline throughput changes, elbow with big curvature radius or elbow with small curvature radius when elevation changes, these are all problems faced in pipeline process design. Therefore, the research results can provide some basis for pipeline process design. Meanwhile, the study of mixed oil can provide a reference for tracking and cutting of mixed oil.