珠海某天然气液化流程的优化分析与动态模拟

Optimization analysis and dynamic simulation of a natural gas liquefaction process in Zhuhai

为提高珠海某天然气液化项目的能源利用效率,采用Aspen HYSYS软件,进行了单循环混合制冷剂液化流程的稳态模拟。选择系统最小功耗为目标函数,LNG换热器最小换热温差为约束条件,黑箱法(BOX)为优化方法,对混合冷剂配比和冷剂蒸发冷凝压力进行了优化;基于优化前后冷热流体复合曲线及LNG换热器换热温差曲线的变化,对优化结果进行了分析;进一步建立动态模型,考察了天然气流量、温度和组分波动时,系统的动态响应曲线。结果表明,优化后,液化流程总功耗降低了10.83%,整体(火用)效率提高了14.20%;受到外界干扰时,系统控制方案会通过改变制冷剂流量作出响应,从而达到新的平衡。

In order to improve the energy utilization efficiency of a natural gas liquefaction project in Zhuhai, the steady-state simulation of the single cycle mixed refrigerant liquefaction process was carried out using Aspen HYSYS software. The minimum power consumption of the system was selected as the objective function, the minimum heat transfer temperature difference of the LNG heat exchanger was selected as the constraint condition, and the black box method(BOX) was selected as the optimization method to optimize the proportion of mixed refrigerant and the evaporation and condensation pressure of refrigerant. The optimization results were analyzed based on the changes of the composite curve of cold and hot ffuids and the temperature difference curve of LNG heat exchanger before and after optimization. The dynamic model was further established to investigate the dynamic response curve of the system when the natural gas ffow, temperature and composition ffuctuated. The results show that after optimization, the total power consumption of the liquefaction process is reduced by 10.83%, and the overall exergy efficiency is increased by 14.20%. In case of external interference, the system control scheme will change the refrigerant ffow to respond, so as to achieve a new balance.