Ethane is different from natural gas, crude oil, etc., its critical temperature is low, and it is easy to change phase with the change of ambient temperature. Therefore, it is necessary to increase the constraint condition to ensure that ethane is in the gas phase. Therefore, based on the optimization principle, the calculation model of the economical flow rate of the ethane transport pipeline including the ethane phase, the pipeline stability, and the compressor pressure ratio constraint is established with the lowest annual cost of the gas phase ethane pipeline. Solve the problem with the lowest cost. The gas-phase ethane transmission pipeline proposed in Tarim Oilfield is analyzed as an example. The results show that the economical flow rate of the pipeline under different working conditions ranges from 3 to 7 m/s, which guides the selection of the diameter of the Tarimethane pipeline. The economic design, safe operation and management of the ethane pipeline provide the basis.

During the operation of heated oil transportation pipeline, the shutdown is caused by some pipeline accidents or repairing. In order to ensure the safety operation of the pipeline, determine the temperature drop and restart pressure needed at different shutdown lasting time is important. This paper builds the heated oil pipeline shutdown and restart mathematic model based on heat transfer and fluid mechanics theory. The VB and MATLAB hybrid programming method which is on the basis of COM technical is utilized to develop heated oil pipeline shutdown and restart simulation software. The software application shows using of VB and MATLAB hybrid programming method can reduce the work of algorithm developing and enhance the reliability of heated oil pipeline shutdown and restart simulation software.

During the operation of a heated oil transportation pipeline, the shutdown was caused by some pipeline accidents and repairing. In order to ensure the safety operation of the pipeline, determine the temperature drop and restart pressure was needed at different shutdown is important. This paper builds the heated oil pipeline temperature drop model after shutdown based on the unsteady heat transfer theory and restart model based on fluid transient flow theory. In order to solve the models, MATLAB is adopted a code for the models solving program. VB and MATLAB hybrid programming method which is on the basis of COM technical is utilized to develop a friendly man-machine interface for the heated oil pipeline shutdown and restart simulation software. The practical application shows using of VB and MATLAB hybrid programming method can reduce the work of algorithm developing and enhance the reliability of heated oil pipeline shutdown and restart simulation software.