The Comprehensive Composition Of Exergy Flow And Exergy Loss Analysis In Waxy Crude Oil Transpotation Process

As the energy problem is becoming more and more serious in the 21 st century, energy conservation has become a worldwide concern. With the development of national economy,energy consumption is increasing day by day. As an important source of energy, a lot of oil is explored for industrial and agricultural production in our country every year. Most oils produced in china are waxy crude oil, which has poor liquidity at normal temperature. Thus the heated oil transportation method is adopted, generally. However, hot oil pipelines often exist the disadvantage of high energy consumption, so it is of great significance to carry out energy utilization analysis on the waxy hot oil pipeline.On the basis of basic theories of thermodynamics exergy analysis, the calculation methods of physical exergy and chemical exergy are derived in this paper, according to the characteristics of waxy crude oil. The factors of physical exergy, especially specific heat exergy and specific pressure exergy are also presented. Based on the traditional calculation method of fuel chemical exergy, the chemical reaction exergy of waxy crude oil in the oilfield is given. Moreover, the calculation results in this paper are proved to be available by comparing the chemical reaction exergy value of heavy oil provided by predecessors. And in view of wax molecules diffusion deposition during pipeline progress, the equation of chemical diffusion exergy of waxy crude oil is proposed, according to the general calculation method of chemical diffusion exergy. The change law of specific diffusion exergy during pipeline progress is also presented. At last, on the basis of exergy balance analysis model,exergy losses during pipeline transportation are divided into different categories against the characteristic of waxy crude oil transportation technology. And taking an oil pipeline in oilfield as an example, the distribution of different exergy losses along the pipeline under different conditions, such as different outlet temperatures, different outlet pressure, different flux and different thermal insulating layer thickness is studied. The influence degree of these factors on exergy loss distribution during pipeline process is pointed out, which provides theoretical basis for the safe and economic operation of practical pipeline.