The up-to-date standard about exergy analysis and its implementation example in methanol synthesis process

As an evaluation tool, exergy analysis method urgently requires the technical standard to perform energy management. However, the update of related standard is rarely found for more than a dozen years. China is issuing the third version of its exergy analysis standard (GB/T 14909-2021). As the members in the drafting group, authors of this work introduce the main amendments made in GB/T 14909-2021. First, the new environmental reference state was established, the new models to estimate the standard exergy and enthalpy of complex fuels were proposed, and the energy grade definition was adopted. Then, this work selected a typical methanol synthesis process as an example of implementing GB/T 14909-2021 for the first time that applies this standard. The rigorous procedure was complied with and the data of material, energy, and exergy balance was obtained. The indexes of energy grade, exergy efficiency, and local exergy loss ratio were evaluated. Finally, some technical measures were proposed to reduce energy loss and to improve the energy consumption level of the system. This implementation example can be referred to for other similar cases of energy and chemical industrial system.