Exergy calculation method based on flowsheeting simulation and its application

A method for calculating exergy was developed based on flowsheeting simulation technology.The accurate exergies of material stream in chemical process could be obtained directly,which were employed as the basic data for exergy analysis and process optimization. The total exergy of a material stream was divided into three terms such that the physical exergy,chemical exergy and mixed exergy,and the thermodynamic data that exergy calculation requires were derived from flowsheeting simulation software HYSYS.The User Variables function was defined to implement the exergy calculation method algorithm.Furthermore,a quantitative evaluation method based on exergy efficiency was established to modify the energy recovery system in the methanation process of coal to synthetic natural gas(SNG).After optimization,the output of 4.8 MPa level steam was increased by 18.4%,and exergy efficiency was improved by 1.4%.