The application scenarios of Phast in air separation projects are briefly intro-duced from both diffusion analysis and explosion analysis.In terms of diffusion analysis,through the diffusion modeling analysis and calculation of emission sources inside and out-side the air separation plant,the influence range of each emission source on the project and the project's surrounding area is obtained,and guidance is provided for the project's plant layout,platform setup,and setup of analysis points.In terms of explosion analysis,the explosion impact value of the explosive source on the surrounding environment is derived from the analysis of the source,which can be used as a reference for the design of equip-ment and buildings.