The Study And Application Of Exergy Transfer And Conversion Law For Crude Oil Pipeline Process

The crude oil produced in our country mostly contains wax and has the characteristics of poor fluidity and tend to be solidified. The continuous pipeline operation requires a lot of power and heat consumption, so the research on energy saving methods in the pipeline transportation of the heating process is significant not only to efficient use of energy and cost saving, but also to the environment protection.This paper was based on the energy transfer of dead state thermodynamics theory,and applied the universal law of thermodynamics system in general potential energy function and exergy function to the exergy transfer and conversion analysis of pipeline transportation. Then it summarized the calculation methods of pipeline transportation energy and exergy transfer process.According to the relationship between force and flow,also the basic equation in dynamics,andcombined with the non-equilibrium thermodynamics theory,phenomenological equations of energy transfer from the general start the process of transporting crude oil derived exergy transfer phenomenological equations. With the example of a pipeline exergy transfer coefficient and exergy flow density variation which indicated that the coupling relationship between the temperature field and pressure field has a direct impact on the exergy transfer coefficient.Based on the basic theory of irreversible thermodynamics, analyzed the exergy flow phenomenon which was driven by the intensive quantity potential field gradient force in each irreversible process of crude oil pipeline transportation. Combined the basic balance equations of crude oil pipeline process with exergy balance dynamic equations of the generalized thermodynamic system, inferring the equations of the heat and pressure pipeline process exergy transfer and conversion equations, then establishing the total exergy transfer equation in the pipeline process, which could provide theoretical and reasonable basis for applying exergy transfer and conversion law to the pipeline energy saving system.A pipeline transportation evaluation method was established, using pressure and heat exergy consumption cost of crude oil as indexes which based on the unit consumption theory. This pipeline transportation unit consumption evaluation method focused on the additional unit consumption which caused by irreversibility during the transporting process. The system makes quantitative analysis to the pipeline runningconsumption value and cost, which provides a new way of thinking to improve the actual transportation process.