Study On The Economical Pigging Period Of Waxy Crude Pipeline

Most crude oils producted in our country is waxy crude. Flowability of this kind of oil is poor, and wax deposition easily happens. Considering this point, wax removal should be taken when the pipeline has been working for a certain period. The thesis will discuss how to fix the economical pigging period to reduce the opetating cost of the oil pipeline, which can provedes theory basis for the engineering application.First, the thesis introduces the mechanism of wax deposition and analizes the influencing factors to it. Then the wax deposition situation is taken into research according to the operating parameters, like the coefficient of heat transmission, the frictional force, the shear stress, especially the washing effect of the oil stream, and so on. This paper tries to find out the relationship between the wax deposition and the power consumption and the fuel consumption, and establishes the function used to evaluate the operating cost, which combines the cost with the pigging period. The economical pigging period is the one when the operating cost is lowest. In addition, a program is written according to the function. Several cases are applied in the program, and the data are carefully calculated and analized. Based on those data and the some infuential factors, like the frictional force and the shear stress, the thesis detailedly describes the effects of the oil temperature, the output and soil temperature on the power consumption, the fuel consumption, the pigging and the operating cost, and finally fixs the economical pigging period.