针对天然气液化过程存在能耗大、成本高等问题，通过以Peng-Robinson热力学模型为基础的工艺流程模拟探讨了中、高压冷剂压力和温度对装置单位能耗的影响规律，利用二次回归正交设计进行了优化改进并验证了优化改进方案的可靠性。结果表明，由二次回归正交设计拟合得到的回归方程不但能够准确描述混合冷剂各关键操作参数与装置单位能耗之间的关系，而且还可以有效地预测最佳工艺条件。当中、高压冷剂的压力和温度分别为1 890、3 760 kPa及38、37℃时，天然气液化装置实际单位能耗仅为393.228 kWh/t，较改进前降低了5.54%，节能效果显著。

To solve the problems including high energy consumption and cost during natural gas liquefaction, the technological process simulation is performed on the basis of Peng-Robinson thermodynamic model and the effect of pressure and temperature of mid-and high-pressure refrigerants on unit energy consumption are explored.The quadratic regression orthogonal design is used to optimize and improve natural gas liquefaction device and the reliability of the optimized and improved scheme is also verified.The results demonstrate that the regression equation obtained by quadratic regression orthogonal design fitting can describe accurately the relationships between key operation parameters of mixed refrigerants and unit energy consumption, and can also predict validly the optimum process conditions.When pressure and temperature of mid-and high-pressure refrigerants are 1 890 kPa, 3 760 kPa and 38℃, 37℃, respectively, the actual unit energy consumption of natural gas liquefaction device is only 393.228 kW·h/t LNG, a drop of 5.54% than before.The optimization plays a very remarkable role in energy saving.