基于PR方程、一般气体状态方程得到压缩因子方程；基于气相和液相逸度方程进行求解，可以得到大多数单一纯净物质的相平衡曲线，本算例以甲烷为例(The equation of the compression factor can be obtained based on　the PR equation and the general gas state equation . Based on the gas phase and liquid phase fugacity equation, the phase equilibrium curve of most single pure matters can be obtained,this example is about the calculation of CH4)