Adaptability Study On The Physical Property State Equation Of Natural Gas

Natural gas occupies a large share of energy utilization in the new century because of its clean and environmental protection characteristics,and the demand is increasing day by day.Compressors are widely used for transportation,liquefaction and compression of natural gas,which can be found in the production and consumption of natural gas,the natural gas compressor which runs smoothly,continuously and efficiently plays a good role in promoting the use and development of natural gas.The calculation of medium properties of natural gas plays an important role in the thermal design and optimization of compressors,at present,there are many kinds of components in natural gas,and the calculation methods of physical properties have shown diversified development,it is particularly important to study the adaptability of different state equations in the physical calculation of natural gas.Based on a part of a scientific research project cooperated with an enterprise,this paper mainly studies the adaptability of four different state equations,PR,LKZX,BWRS and Helmholtz,in the calculation of physical properties of natural gas.Identification through literature,the REFPROP software has a high accuracy in the calculation of natural gas physical properties,and the author reviews a large number of literatures,collects and sorts out experimental data,applies PR,LKZX,BWRS,Helmholtz equation and REFPROP to the calculation of eight types of typical physical properties and conducts comparative analysis with experimental data to verify the accuracy of the REFPROP,and the results show that REFPROP can serve as a reference data source for calculation and comparison of natural gas physical properties.In order to study the adaptability of four different state equations,according to the types and state point parameters of natural gas mixtures,eleven types of typical physical properties are divided into conventional physical properties,thermodynamic properties,transport properties and gas-liquid equilibrium properties,with the physical property data calculated by REFPROP as the standard reference value,the results of PR,LKZX,BWRS and Helmholtz equations are compared and analyzed by using the analysis method of average relative error and average absolute error,and the conclusion that Helmholtz equation has the best adaptability in natural gas physical properties calculation is obtained.Finally,this paper also focuses on the matching program design of different state equations applied to natural gas physical property calculation,and details the technical route,algorithm flow and program structure framework of the matching program design in detail.According to the above-mentioned physical properties calculation data of natural gas,3typical mixtures and their calculation results are selected to verify the program.The results show that the matching program is feasible and highly reliable,which lays a solid foundation for the development of subsequent software of physical properties calculation of natural gas.