Theoretical analysis on effects of flow state change upon pipeline operating cost

In the operation of a hot oil pipeline, internal oil temperature shows progressive axial decline, the operational working conditions of the whole pipeline vary continuously while oil flows advance forward, the crude turns from Newtonian fluid to non-Newtonian fluid, the pipe sections under different flow states have different friction loss, so the sections need different pressure heads, and the calculations shall be accomplished by section. Take the case of no bypass oil transmission pipelines between pump stations as an example, the effects of variable inlet/outlet oil temperatures upon the length and friction loss of the pipe sections under different flow states are determined by calculations, and the relevant mathematical model is constructed to analyze the effects of flow state change upon the operating cost of the oil pipeline system. The oil transportation programs directing at different flow states are analyzed comparatively, and the optimal oil transportation program between hot oil pipeline stations in the calculation cases is decided on the condition that smooth fulfillment of oil transportation tasks is ensured.